JP,09-237399,A(1997)

PATENT ABSTRACTS OF JAPAN

(11)Publication number : 09-237399

(43)Date of publication of

application :

09.09.1997

(51)Int.Cl. G08G 1/042

B60R 21/00

G01R 33/02

G01V 3/08

G01V 3/10

// G01C 21/00

(21)Application

number :

08-

043933

(71)Applicant

:

CANON ELECTRON

INC

(22)Date of filing : 01.03.19

96

(72)Inventor : KAWASE

MASAHIRO

TAZAKI SHINICHI

(54) METHOD, DEVICE AND SYSTEM FOR VEHICLE DETECTION

(57)Abstract:

PROBLEM TO BE SOLVED: To improve

reliability by making the magnetic

detection of an vehicle highly precise

through the use of a magnetic sensor

consisting of plural small magnetic

detection elements.

SOLUTION: The magnetic sensor 12

plurally arranging along the

longitudinal direction of the vehicle

the magnetic detection elements 1A

to 11N with magnetic field detecting

sensitivity in a direction vertical to the

ground is installed on or in the ground

within the passing width of the

vehicle. Through the use of a selector 21, a timer counter 20 and RAM

26 storing the early value of external magnetic intensity, a control

part 19 measures each change of external magnetic field intensity

basing on the state of no vehicle with respect to each magnetic

detection element as a reference based on the intensity of external

magnetic field detected by each magnetic detection element. Then

the part 19 judges vehicle detection depending on whether the total

sum of the respective absolute values of the measured values

exceeds a prescribed combined threshold values.

CLAIMS

[Claim(s)]

[Claim 1]In a vehicle detecting method which detects a magnetic field

generated from vehicles with a magnetic sensor, and detects vehicles

magnetically, A magnetic sensor which put in order two or more

magnetism detecting elements which have magnetic field detection

sensitivity in the direction vertical to a ground surface along with a

vehicles longitudinal direction is installed in a ground surface in a

band pass of vehicles, or underground, A vehicle detecting method

detecting vehicles by the judgment of whether external magnetic

field intensity change as on the basis of the state where each of two

or more of said magnetism detecting elements detects external

magnetic field intensity, and there are no vehicles is measured, and

total of an absolute value of two or more measurement values of this

measuring result exceeds predetermined joint threshold S.

[Claim 2]The vehicle detecting method according to claim 1 setting

said joint threshold S as a value of a product which hung threshold s

in the case of one magnetism detecting element, and a square root of

the addition numbers n of said measurement value added in order to

ask for said total.

[Claim 3]An absolute value of two or more measurement values of a

measuring result of the aforementioned external magnetic field

intensity change is arranged in descending, it is considered as |

deltaH(k) | (k= 1, 2, ordinal number of --), and they are the following

expression about this value, threshold s in the case of one magnetism

detecting element, and a square root of said addition numbers n.

[Mathematical formula 1]

The vehicle detecting method according to claim 2 judging with

having detected vehicles when it compared whether it is alike, it

would set, would substitute one by one from k= 1, and the above-

mentioned expression would be satisfied and the above-mentioned

expression was satisfied.

[Claim 4]The vehicle detecting method according to claim 2 or 3

setting threshold s in the case of said one magnetism detecting

element as the range of 0.05-0.1 gauss.

[Claim 5]It is a vehicle detecting device which detects a magnetic

field generated from vehicles with a magnetic sensor, and detects

vehicles magnetically, A magnetic sensor which consists of two or

more magnetism detecting elements arranged so that it may have

magnetic field detection sensitivity in the direction vertical to a

ground surface and may rank with a ground surface in a band pass of

vehicles, or underground along with a vehicles longitudinal direction,

A measurement means which measures each of external magnetic

field intensity change as on the basis of the state where there are no

vehicles to each magnetism detecting element, based on external

magnetic field intensity detected by each of two or more of said

magnetism detecting elements, A vehicle detecting device having a

judging means which judges vehicle detection by whether total of

each absolute value of a measurement value of external magnetic

field intensity change measured by this measurement means exceeds

predetermined joint threshold S.

[Claim 6]It has a memory measure which memorizes a value of

external magnetic field intensity detected by said two or more

magnetism detecting elements in the state where said measurement

means does not have vehicles as an initial value used as a standard,

The vehicle detecting device according to claim 5 measuring the

aforementioned external magnetic field intensity change on the basis

of an initial value memorized to this memory measure.

[Claim 7]A Colpitts oscillator in which said magnetism detecting

element incorporated a magnetic impedance component which

attached a coil, It comprises a comparator [ predetermined

comparison voltage / output / of a detector circuit which detects an

output of this oscillator and this detector circuit ], By detecting

external magnetic field intensity, applying an AC bias magnetic field

to said magnetic impedance component with said coil, A Pulse-

Density-Modulation output in which a pulse which is two kinds from

which pulse width differs according to external magnetic field

intensity in an output of said comparator appears by turns is

obtained, The vehicle detecting device according to claim 5 or 6,

wherein said measurement means measures external magnetic field

intensity change as on the basis of the state where ask for data of a

difference of pulse width of two kinds of said pulses as external

magnetic field strength data, and said vehicles cannot be found based

on this data.

[Claim 8]It is a vehicle detection system which carries out vehicle

detection to any 1 clause from Claim 5 to 7 using a vehicle detecting

device of a description, A judging means which judges whether

whether vehicles advanced on a magnetic sensor, whether it stopped

on a magnetic sensor based on a decided result of vehicle detection

by a judging means of said vehicle detecting device, and on a

magnetic sensor were left, Car presence information on a purport that

vehicles have stopped on a magnetic sensor based on a decided

result of this judging means, And a vehicle detection system

characterized by having an output means to which vehicles output

**** information on a purport that on a magnetic sensor was left, and

enabling it to manage parking vehicles with the output of said car

presence information and **** information.

DETAILED DESCRIPTION

[Detailed Description of the Invention]

[0001]

[Field of the Invention]This invention detects the magnetic field

generated from vehicles, such as a car, with a magnetic sensor, and

detects vehicles magnetically, namely, relates to the vehicle

detecting method which detects the existence of vehicles thru/or

passage, a vehicle detecting device, and a vehicle detection system.

[0002]

[Description of the Prior Art]Conventionally, the sensor which detects

vehicles, such as a car, is used in the use of measuring the distinction

of the existence of parking in the managerial system of a motor pool,

and the traffic of the vehicles in a traffic control system.

[0003]Usually, since vehicles, such as a car, are tinged with

magnetism using the metallic material which is easy to be tinged with

magnetism, such as a steel plate, it is detecting the magnetic field

generated from vehicles with a magnetic sensor, and it is possible to

recognize existence of vehicles or passage.

[0004]Conventionally, in the motor pool, the loop coil type magnetic

sensor was buried in the earth, and it has been used for vehicle

detection in it. A loop coil type magnetic sensor is that generate a

magnetic field by an eddy current in the metal part of the body of

vehicles to the alternating current sent through a coil, or the

magnetic field from the body's own magnetization interlinks with a

loop coil, A coil's own inductance changes, it is changed as change of

oscillating frequency or amplitude in a circuit, and vehicle detection is

performed by the existence of the change.

[0005]However, although the loop coil type magnetic sensor is

spreading by detection of vehicles, it has the following problems.

[0006]- Since a loop coil opens an interval a little with vehicles and is

installed, in order to detect the inductance variation in vehicles

existence, there is the necessity of enlarging size of a sensitivity

secured upper coil (about 1mx1m).

[0007]- If metal bodies, such as a steel rod, are in the neighborhood,

S/N cannot be taken enough.

[0008]- Since a loop coil is large and power consumption is large, it is

not fit for continuous energization use.

[0009]- A coil is a size which is about 1mx1m, and the burden of

construction expense is heavy in subterranean installation.

[0010]Then, although the small magnetic sensor was used and the

substitution was considered, When the magnetic field generated from

a vehicles pars basilaris ossis occipitalis was measured, near the zero

crossing point which remarkable unevenness is made to distribution

of magnetic field strength, and magnetic field polarity reverses by the

local magnetization of Body Manufacturing Division article each which

it has, it turned out that the dead point which does not exceed a

threshold required for the judgment of vehicle detection arises.

[0011]

[Problem to be solved by the invention]Then, a reliable vehicle

detecting method in which SUBJECT of this invention can perform

magnetic detection of vehicles with high precision using the magnetic

sensor which consists of two or more small magnetism detecting

elements, And it is in providing the vehicle detection system which is

a vehicle detecting device which performs vehicle detection by the

method, can attain a miniaturization and can be used effective in

management of parking vehicles using the vehicle detecting device of

low power consumption, and this vehicle detecting device.

[0012]

[Means for solving problem]In the vehicle detecting method which

according to this invention detects the magnetic field generated from

vehicles with a magnetic sensor, and detects vehicles magnetically in

order to solve above-mentioned SUBJECT, The magnetic sensor which

put in order two or more magnetism detecting elements which have

magnetic field detection sensitivity in the direction vertical to a

ground surface along with the vehicles longitudinal direction is

installed in the ground surface in the band pass of vehicles, or

underground, The external magnetic field intensity change as on the

basis of the state where each of two or more of said magnetism

detecting elements detects external magnetic field intensity, and

there are no vehicles was measured, and the method of detecting

vehicles by the judgment of whether total of the absolute value of two

or more measurement values of this measuring result exceeds

predetermined joint threshold S was adopted.

[0013]According to such a vehicle detecting method, the influence of

the zero crossing point which the magnetic field polarity looked at by

distribution of the magnetic field strength in the case of measuring

the magnetic field generated from a vehicles pars basilaris ossis

occipitalis reverses can be avoided, and highly precise and reliable

vehicle detection can be performed.

[0014]According to this invention, it is a vehicle detecting device

which detects the magnetic field generated from vehicles with a

magnetic sensor, and detects vehicles magnetically, The magnetic

sensor which consists of two or more magnetism detecting elements

arranged so that it may have magnetic field detection sensitivity in

the direction vertical to a ground surface and may rank with the

ground surface in the band pass of vehicles, or underground along

with a vehicles longitudinal direction, The measurement means which

measures each of external magnetic field intensity change as on the

basis of the state where there are no vehicles to each magnetism

detecting element, based on the external magnetic field intensity

detected by each of two or more of said magnetism detecting

elements, Total of each absolute value of the measurement value of

external magnetic field intensity change measured by this

measurement means adopted the composition of the vehicle

detecting device which has a judging means which judges vehicle

detection by whether predetermined joint threshold S is exceeded.

[0015]While being able to perform reliable vehicle detection with high

degree of accuracy with the vehicle detecting method of this

invention according to such composition, the magnetic sensor can

consist of small size which consists of plurality of the small

magnetism detecting element constituted, for example using the

magnetic impedance component as a magnetic sensor of low power

consumption.

[0016]It is a vehicle detection system which performs vehicle

detection using the vehicle detecting device by above-mentioned this

invention according to this invention, The judging means which

judges whether whether vehicles advanced on the magnetic sensor,

whether it stopped on the magnetic sensor based on the decided

result of the vehicle detection by the judging means of said vehicle

detecting device, and on the magnetic sensor were left, The car

presence information on the purport that vehicles have stopped on a

magnetic sensor based on the decided result of this judging means,

And it has an output means to which vehicles output the ****

information on the purport that on the magnetic sensor was left, and

the composition of the vehicle detection system which enabled it to

manage parking vehicles with the output of said car presence

information and **** information was adopted.

[0017]According to such composition, the advantage of the vehicle

detecting device of this invention can be enjoyed, exact car presence

information and **** information can be outputted based on highly

precise and reliable vehicle detection, and it can use effective in

management of parking vehicles.

[0018]

[Mode for carrying out the invention]Hereafter, an embodiment of the

invention is described with reference to figures.

[0019][Embodiment of a vehicle detecting method] Drawing 1 - 3

explain the embodiment of the vehicle detecting method by this

invention first.

[0020]In this embodiment, as shown in drawing 1, to the ground

surface 14 in the width which the vehicles (car) 10 pass, or

underground. The magnetic sensor 12 which has arranged two or

more magnetism detecting elements 11A, 11B, and 11C which have

magnetic field detection sensitivity in the direction (Z direction)

vertical to a ground surface so that it may stand in a line along with

the longitudinal direction of the vehicles 10 is installed, and vehicle

detection is performed.

[0021]The external magnetic field intensity change as on the basis of

the state where each magnetism detecting element of the magnetic

sensor 12 detects external magnetic field intensity, and there are no

vehicles 10 is measured, and total of the absolute value of two or

more measured magnetic-field-strength change detects vehicles by

the judgment of whether to exceed a predetermined joint threshold.

[0022]This method was drawn from the following examining results.

[0023]First, on the ground surface 14 in the width which the vehicles

10 pass as shown in drawing 2, The magnetic sensor 12 which

comprised one magnetism detecting element which has magnetic

field detection sensitivity in the Z direction which is a vertical

direction to the ground surface 14 is arranged, the vehicles 10 were

moved on the sensor 12, the magnetic sensor 12 detected external

magnetic field intensity, external magnetic field intensity change was

measured, and the situation of the change was investigated. The

variation of external magnetic field intensity made the measurement

value in the state where there are no vehicles 10 the initial value

used as a standard, and displayed a changed part from it. The

element using the magnetic impedance component mentioned later

as a magnetic sensing device was used for the magnetism detecting

element. Two or more vehicles performed the sampling. Four data

measuring of a characteristic example is shown in drawing 2 (a) - (d)

in it.

[0024]Generally, magnetic field distribution of the cross direction of a

bar magnet has a peak of reverse polarity at both ends of the bar

magnet 16 like drawing 3, and has a tendency which carries out a

zero cross in the center section. On the other hand, it can guess that

the body of a car constitutes a roughly big bar magnet from a

vehicles longitudinal direction from it being in agreement with how of

data measuring of drawing 2 to lengthen the skirt near the both-ends

peak of magnetic field distribution of drawing 3 by (c) and (d),

especially, if it observes near the both ends of a magnetic field

change. However, attitude of a peak has dispersion considerably by

overall magnetic-field-strength distribution, and it does not become a

beautiful form like a bar magnet because local magnetization exists

by part each of a body pars basilaris ossis occipitalis.

[0025]Since detection of vehicles will detect a magnetic field of a

body center section if detection of parking vehicles is taken into

consideration, for example, it observes a magnetic field of a center of

the body by width of the length of a half of the body shown in the

range of H seal in a figure of each data measuring of drawing 2. It is

because movement speed of a difference in the length of each body

and the body at the time of Measurement Division had dispersion that

the length of H seal differs.

[0026]Also when unevenness is looked at by magnetic-field-strength

change within the limits of H seal of data of four examples and a zero

cross exists, an absolute value of a measurement value may go into a

DETTO point on which it is less than threshold s, and one magnetism

detecting element is not enough as it for vehicle detection at a

certain thing.

[0027]When threshold s of one magnetism detecting element

considers resolution of a magnetism detecting element, and S/N of a

circuit, 0.05 gauss of a minimum is a limit, and considering that a

maximum has about 0.1 gauss vehicles like drawing 2 (c) in the

maximum of a magnetic field change by vehicles, it is difficult to set

up exceeding 0.1 gauss.

[0028]Then, two or more magnetism detecting elements are arranged

along with a vehicles longitudinal direction, and if vehicle detection is

carried out by whether either exceeds threshold s, detection

probability will increase.

[0029]However, in a case of vehicles of drawing 2 (d), when four

magnetism detecting elements have been arranged to each of a

position corresponding to four points, a in a figure, b, c, and d, a

measurement value by which element will also be less than 0.05

gauss. If such a case is taken into consideration, a device which raises

detection probability further is required.

[0030]Then, an absolute value of a measurement value of two or

more magnetic-field-strength change which detected external

magnetic field intensity by each of two or more magnetism detecting

elements, and was measured is added, A value of a product which, on

the other hand, hung said number (addition numbers of a

measurement value) n of a magnetism detecting element of added

square roots on threshold s at the time of detection by an

independent magnetism detecting element is set up as joint threshold

S, If vehicle detection is judged by whether total of an added result of

said absolute value exceeds joint threshold S, it is detectable by high

probabilities.

[0031]A noise component serves as a mean square to addition of an

output of each magnetism detecting element, and if it is considered

as a noise component of the respectively same size, this will use that

a product of a noise for one element and a square root of the addition

numbers n serves as a noise at the time of combination, and will try

to earn the whole S/N.

[0032]For example, magnetic-field-strength change, a of the data

measuring of the vehicles of drawing 2 (d), b, c, and d, of four points,

It will be 0.03G-0.04G-0.02G-0.03G, and if threshold s of independent

detection is set to 0.05G, when these are added, it will be 0.12G, and

0.05xroot4=0.1 gauss is set to joint threshold S, total of the added

result of an output will exceed joint threshold S, and detection of it

will be attained.

[0033]Therefore, when the magnetic field component of a direction

vertical to the ground surface of the magnetic field generated from

vehicles is detected by two or more Magnetism detecting elementn

and the magnetic-field-strength change by vehicles existence is

measured, It turned out that it is suitable that the total adding each of

the absolute value of magnetic-field-strength change measured based

on the detection result of n magnetism detecting elements of a result

performs vehicle detection by whether joint threshold S as

independent threshold sxrootn is exceeded.

[0034]By the way, since a magnetic-field-detection output may

become near a zero cross with a certain element and total of the

above-mentioned added result may become low when detecting as

mentioned above by two or more magnetism detecting elements, the

method explained below can also be chosen as a method of raising

vehicle detection efficiency further.

[0035]Arrange in descending each absolute value of the

measurement value of the external magnetic field intensity change

from the initial value which detected external magnetic field intensity

by two or more magnetism detecting elements of the magnetic

sensor mentioned above, and was measured, consider it as |deltaH(k)

| (k= 1, 2, ordinal number of --), and Namely, this value, They are

[ threshold s in the case of one magnetism detecting element, and ]

the following expression about said addition numbers n.[0036]

[Mathematical formula 2]

[0037]It compares whether it is alike, it sets, substitutes one by one

from k= 1, and the above-mentioned expression is satisfied, and

when the above-mentioned expression is satisfied, it judges with

having detected vehicles.

[0038]According to this method, vehicle detection efficiency can be

raised by adding the measurement value of two or more external

magnetic field intensity change to descending one by one, and using

for the judgment of vehicle detection.

[0039]In above-mentioned explanation, the "ground surface of

"underground" meaning the inside of those fields including all the

fields that vehicles, such as a floor line in the building of not only the

ground surface of the ground, and the road surface of a road and the

ground surface of an outdoor parking lot but a multi-level car parking

tower, run fields thru/or park" of 14 is natural.

[0040][Embodiment of a vehicle detecting device] Next, the

embodiment of a vehicle detecting device which enforces concretely

the vehicle detecting method mentioned above, and performs vehicle

detection is described.

[0041]First, the magnetism detecting element of the magnetic sensor

used for a vehicle detecting device is explained. Being required of this

magnetism detecting element should be 10 or more milligauss in (1)

magnetic field detection sensitivity.

[0042](2) There is two or more dispersion [ little ] of the performance

of an element for use.

[0043](3) Considering ground surface installation, the height of an

element should be several millimeters.

[0044](4) The detector circuit of an element is excellent in a noise-

proof and temperature characteristics, and be low power

consumption.

[0045]Although there is a flux gate type magnetism detecting

element as what satisfies the conditions of (1), if it is going to raise

detection sensitivity with this element, several 10 mm of the length of

an element will be needed, and it will not be satisfied with it of the

conditions of (3).

[0046]Since it is easy to come out of dispersion in performance, a

problem produces a flux gate type magnetism detecting element also

on condition of (2).

[0047]Then, the magnetism detecting element constituted using a

magnetic impedance component is seemed that it is the optimal by it.

[0048]The magnetic impedance component is indicated by JP,H7-

181239,A and the element body as a magnetic body is constituted

from an amorphous wire or these days by the magnetic thin film etc.

If the high frequency current of an MHz band is impressed to this

element body, according to a magnetic impedance effect, according

to an external magnetic field, the impedance of an element body

changes several 10%, and can detect an external magnetic field using

this.

[0049]Sensitivity of a magnetic impedance component has the

sensitivity of a 10-5 gauss stand, and number milligauss is securable

and it is satisfied also with practical resolution in a case where it

connects with a circuit of a magnetism detecting element of

conditions of (1).

[0050]From there being little influence of a demagnetizing field, it is

easy for the length of an element to be 5 mm or less, and conditions

of (3) are also cleared.

[0051]About dispersion in performance, when supplied with an

amorphous wire, since it is easy to control thickness, dispersion in

performance resulting from an outside dimension of a magnetic body

of an element body is pressed down, and is satisfied with that there is

little dispersion in a path of a wire, and a magnetic film of conditions

of (2).

[0052]Although application was considered according to contents

reported at a society etc. about magnetic field detection which uses

the Colpitts oscillating circuit about conditions of (4), there is a

problem practically.

[0053]For example, an application of a magnetic field sensor as an

azimuth sensor is shown by an "amorphous wire MI Colpitts oscillation

type micro magnetic sensor" announced at the 18th Maganetics

Society of Japan academic lecture meeting (14pB-7).

[0054]In composition of this azimuth sensor, an amorphous wire is

included in a Colpitts type oscillator, and since change of an external

magnetic field turns into change of oscillation amplitude and it

appears, an output is obtained through a detector circuit. While

sending a direct current through a coil directly twisted around a wire

of an element, applying a DC bias magnetic field and making it

operate in a field where sensitivity is high, he is trying to know the

polarity of the direction of north and south.

[0055]However, in minute magnetic field detection, such as

geomagnetism (about 0.3 gauss) by this method. Change of an output

after a detector circuit is as small as several percent, and in order to

treat absolute value change of oscillation amplitude as an output as it

is, sufficient S/N is not obtained from it being easy to be influenced by

change of power supply voltage, the temperature characteristics of

an element, etc. by amplitude fluctuation, and it is unreliable.

[0056]So, in this embodiment, circuitry of a magnetism detecting

element shown in drawing 4 was adopted.

[0057]Circuitry of a magnetism detecting element shown in drawing 4

consists of a Colpitts oscillator, a detector circuit, and a comparator,

the magnetic impedance component 1 mentioned above is included

in a Colpitts oscillator, it direct-winds, or the magnetic impedance

component 1 is approached, and the coil 2 for bias is formed.

[0058]In this composition, AC bias current Ib is sent through the coil

2, and an about **1-**2 gauss AC bias magnetic field is impressed to

the magnetic impedance component 1. As shown in (a), amplitude

modulation of the oscillation output which appears like the after-

mentioned by this at an A point in a figure of a Colpitts oscillator

according to intensity of the external magnetic field Hex for [ which is

impressed to the magnetic impedance component 1 ] detection is

carried out, A ripple waveform corresponding to a bias magnetic field

which has the difference of elevation of an adjacent peak

corresponding to intensity of the external magnetic field Hex by

detecting this in a detector circuit at a B point as shown in (b) is

acquired, By carrying out a party rate with the comparison voltage

Vref which crosses a voltage waveform of said ripple with a

comparator, a Pulse-Density-Modulation output corresponding to

intensity of the external magnetic field Hex can be obtained at C

point.

[0059]A signal of AC bias current Ib carries out dividing of the clock

from a microcomputer judgment part mentioned later, with a low pass

filter, it may be made into a sine wave or the shape of a triangular

wave, and it may throw it in, or may provide and throw in an oscillator

individually.

[0060]Next, details of operation of circuitry of a magnetism detecting

element of drawing 4 mentioned above are explained.

[0061]the characteristic of a magnetic impedance component is

symmetrical with the direction of +- in several gauss to the external

magnetic field Hex, as shown in drawing 5 -- a V character-like

impedance change is shown in general. As shown in drawing 5 (a) as

a principle of operation of the magnetic impedance component 1 of

drawing 4, when there is no external magnetic field, an AC bias

magnetic field is +. - It touches symmetrically, In change of

impedance to it, an impedance change which the difference of

elevation does not have in peaks on a ripple breaks out by a magnetic

field twice the frequency of AC bias.

[0062]Since an AC bias magnetic field and an unsymmetrical

magnetic field which an external magnetic field superimposed will

start the magnetic impedance component 1 like drawing 5 (b) there if

an external magnetic field is impressed to a longitudinal direction of

the magnetic impedance component 1, An impedance change (ripple

waveform) from which height of a peak differs by turns on an

impedance change arises.

[0063]The ripple waveform in an impedance change as showed the

output after detection of drawing 4 (b) which appeared as amplitude

modulation in the oscillation amplitude characteristic of the Colpitts

oscillator as change of this impedance was shown in drawing 4 (a),

and detected that oscillation output in the detector circuit by drawing

5 (b), and a similar signal are acquired. The size of an external

magnetic field is changed into the output of a digital signal by which

Pulse Density Modulation was carried out by carrying out a party rate

with the comparison voltage Vref which crosses a ripple waveform as

the signal is shown in drawing 6 in a comparator. That is, the Pulse-

Density-Modulation output in which the pulse which is two kinds from

which pulse width differs according to external magnetic field

intensity appears by turns is obtained.

[0064]Thus, pulse width [ of two kinds of pulses ] A which appears by

turns, and B can be measured and evaluated using the timer counter

of a microcomputer, and the digital data in which external magnetic

field intensity is shown can be obtained by asking for the digital data

of difference A-B of pulse width by an operation after that. Although

the measurement data of pulse width to a actual external magnetic

field is shown in drawing 7, in **0.5 gauss shows an almost linear

change. The numerical input value of joint threshold S mentioned

above can be decided by transposing the magnetic field strength of

magnetism detecting element independent threshold s to the math-

processing value of pulse width based on this data, and hanging the

several n square root of a magnetism detecting element on it.

[0065]And the digital data of difference A-B of the pulse width

measured in the state where there are no vehicles, in detection of

vehicles is memorized as data of the initial value of the external

magnetic field intensity used as a standard, Then, the absolute value

of the difference of difference A-B of pulse width and the initial value

according to the measured external magnetic field intensity is

calculated as data corresponding to the absolute value of intensity

change of an external magnetic field, It can ask for total of the data of

said absolute value called for by further two or more magnetism

detecting elements, and the existence of vehicles can be judged by

whether the figure exceeded the numerical value of joint threshold S.

[0066]Next, drawing 8 explains the composition of the vehicle

detecting device using the magnetism detecting element of drawing

4.

[0067]Colpitts oscillator 3 incorporating the magnetic impedance

component 1 which wound the coil 2 for bias which 12 is a magnetic

sensor and was mentioned above in the composition of the vehicle

detecting device shown in drawing 8, They are the marks 11A and

11B about the magnetism detecting element of drawing 4 which

consists of the detector circuit 4 and the comparator 5. -- As shown in

11N, N pieces are provided and it is constituted. Magnetism detecting

elements 11A and 11B -- 11N is arranged so that it may rank with the

ground surface in the band pass of vehicles, or underground along

with the longitudinal direction of vehicles as mentioned above, and

each element can be giving magnetic field detection sensitivity in the

direction vertical to a ground surface.

[0068]18 is a microcomputer judgment part which comprises a

microcomputer, analyzes the Pulse-Density-Modulation output of each

magnetism detecting element of the magnetic sensor 12, and judges

the existence of vehicles. The microcomputer judgment part 18,

Either the timer counter 20 which counts pulse width [ of the control

section 19 which performs whole control and various data processing,

and the Pulse-Density-Modulation output mentioned above ] A, and B

or magnetism detecting elements 11A-11N are chosen. It consists of

the selector 21 which inputs the output pulse into the timer counter

20 and the clock generator 22, the clock divider 23, the low pass filter

24, and the bias circuit (amplifier) 25.

[0069]Dividing is carried out so that the clock signal which the clock

generator 22 oscillates may become the range of 1 kHz - 100 kHz by

the clock divider 23 in this composition, The low pass filter 24 and the

bias circuit 25 let this signal by which dividing was carried out pass,

the signal of the AC bias current of a sine wave or the shape of a

triangular wave is formed, and it is impressed by the coil 2 for bias

which are each magnetism detecting elements 11A-11N of the

magnetic sensor 12. The feed zone of this bias current may be

provided in the magnetic sensor 12 side.

[0070]Next, the vehicle detection operation by the composition of

drawing 8 is explained. First, the initial value of the external magnetic

field intensity used as the standard for asking for external magnetic

field intensity change in the state where there are no vehicles is

measured. For this reason, with the magnetic sensor 12, the pulse

signal which detected external magnetic field intensity by two or

more magnetism detecting elements 11A-11N, and carried out Pulse

Density Modulation is outputted as mentioned above, and it sends to

the selector 21 of the microcomputer judgment part 18.

[0071]With the command from the control section 19, the selector 21

chooses and sends two kinds of pulses A and B further mentioned

above while it chooses the output pulse signal of two or more

magnetism detecting elements 11A-11N which should be sent to the

timer counter 20 one by one and sends it.

[0072]In the timer counter 20, the pulse width of two kinds of said

pulses A and B of two or more magnetism detecting elements sent

one by one is counted and evaluated, and the data is sent to the

control section 19.

[0073]In the control section 19, difference A-B of the pulse width data

of A pulse and B pulse evaluated with the timer counter 20 is

computed for every magnetism detecting element, and the measured

value of external magnetic field intensity is calculated. The measured

data is recorded on memory storage, such as RAM26 in the control

section 19, as initial value data used as a standard.

[0074]Then, in order to detect vehicles, the detection and the

Measurement Division of external magnetic field intensity by each

magnetism detecting element are performed in the same procedure

as the above, In the control section 19, it asks separately, absolute-

value-izes by using the difference of said measurement data and

initial value data as external magnetic field intensity change data,

and asks for the total, and the existence of vehicles is judged by

whether it is over predetermined joint threshold S which the total

mentioned above. And in the case of the vehicle detection system

mentioned later, car presence information etc. are taken out based on

the result of said judgment.

[0075]In order not to treat the amplitude of a Colpitts oscillator as an

absolute value in the circuitry of the magnetism detecting element of

drawing 4 as an advantage of the equipment of these above

embodiments probably but to treat a changed part of amplitude, a

low change of the frequency by change, temperature characteristics,

etc. of power supply voltage can be disregarded.

[0076]Since the detect output of the external magnetic field intensity

in the magnetic sensor 12 is digitized-output-ized by the Pulse

Density Modulation by a comparator, The magnetic sensor 12 and the

microcomputer judgment part 18 connect two or more magnetic

sensors 12 to the microcomputer judgment part 18, and can carry out

common use of the microcomputer judgment part 18 to two or more

magnetic sensors 12 while also being able to perform installation to

isolate and obtaining the flexibility of installation.

[0077]Since the whole equipment which constituted the magnetism

detecting element very small, could constitute the magnetic sensor

12 small, and includes the microcomputer judgment part 18 can be

made small, The burden of installation cost is small, and it is low

power consumption, and since the prolonged energization use which

was poor at conventional loop coil type equipment is possible, the use

of vehicle detection is expandable.

[0078][An embodiment of a vehicle detection system] Next, drawing

9 and drawing 10 explain an embodiment of a vehicle detection

system for parking-vehicles management in a motor pool using a

vehicle detecting device of drawing 8 mentioned above. As for this

vehicle detection system, it is needless to say that a portion of the

magnetic sensor 12 is provided in a ground surface of a motor pool or

underground at least, and it carries out of a vehicle detecting device

of drawing 8.

[0079]Drawing 9 is a block diagram showing functional composition of

a vehicle detection system of this embodiment. Composition of those

other than magnetic sensor 12 is specifically realized in drawing 9 by

hardware and software of the microcomputer judgment part 18 of

drawing 8.

[0080]In drawing 9, it realizes from the control section 19 of drawing

8, the timer counter 20, and the selector 21, and the measurement

means 27 measures external magnetic field intensity change as on

the basis of the state where there are no vehicles based on a

detection result of external magnetic field intensity by the magnetism

detecting elements 11A-11N of the magnetic sensor 12 as mentioned

above. This measurement means 27 has the initial value memory

measure 28 which memorizes a value of external magnetic field

intensity detected by the magnetism detecting elements 11A-11N in

the state where there are no vehicles as an initial value used as a

standard, and measures external magnetic field intensity change on

the basis of an initial value memorized to this memory measure 28.

The memory measure 28 is specifically constituted as RAM26 of

drawing 8.

[0081]It realizes as a function of the control section 19, and the

vehicle detection judging means 29 judges vehicle detection as

mentioned above based on the measuring result of the measurement

means 27.

[0082]Penetration, a stop, and the **** judging means 30 are realized

as a function of processing of Step S3 of below-mentioned drawing 10

by the control section 19, S6, and S9, Based on the decided result of

the vehicle detection by the vehicle detection judging means 29.

[ whether vehicles advanced into the motor pool, and ] It is judged

whether on whether it advanced on the magnetic sensor 12 formed in

the motor pool, whether whether whether it having stopped in the

motor pool and a motor pool having been left and vehicles stopped on

the magnetic sensor 12, and the magnetic sensor 12 was left.

[0083]Car presence and the **** information output means 31 are

realized as a function of Step S7 of drawing 10 by the control section

19, and processing of S10, Based on the decided result of

penetration, a stop, and the **** judging means 30, vehicles have

stopped at the motor pool, the car presence information on the

purport that vehicles have stopped on the magnetic sensor 12, and

vehicles left the motor pool, namely, vehicles output the ****

information on the purport that on the magnetic sensor 12 was left.

[0084]External magnetic field intensity is detected by the basis of

such composition by the magnetism detecting elements 11A-11N of

the magnetic sensor 12, The external magnetic field intensity change

on the basis of the state where there are no vehicles by the

measurement means 27 based on the detection result is measured,

and the judgment of vehicle detection is performed by the vehicle

detection judging means 29 based on the measuring result. And

based on the decided result of vehicle detection, penetration of the

vehicles in a motor pool, a stop, and **** are judged by the judging

means 30, and car presence information thru/or **** information are

outputted by the output means 31 based on the decided result.

[0085]Next, drawing 10 explains the details of vehicle detection

operation of this system. Drawing 10 is a flow chart which shows the

procedure of the vehicle detection processing by the control section

19 of drawing 8 which realizes each means 27, 29, 30, and 31 of

drawing 9.

[0086]On vehicle detection processing and first in Step S1 of drawing

10 the control section 19, External magnetic field intensity by each

magnetism detecting element of the magnetic sensor 12 is made to

detect as mentioned above in the state where there are no vehicles, It

asks for measurement data of external magnetic field intensity of A-B

mentioned above based on the detection result, this is set up as initial

value data used as a standard which asks for external magnetic field

intensity change, and it memorizes to recording equipment of RAM26

grade. Since there are no vehicles into a motor pool at this time, the

control section 19 checks **** information.

[0087]Next, in order to judge penetration of vehicles to the magnetic

sensor 12 top formed in penetration of vehicles into a motor pool, i.e.,

a ground surface of a motor pool, and underground, Detection and

Measurement Division of external magnetic field intensity from

vehicles by each magnetism detecting element are performed in a

procedure mentioned above (Step S2), It judges with vehicles having

advanced into a motor pool, when it absolute-value-ized in quest of a

difference of each measurement data A-B and initial value data

separately and the total was over predetermined joint threshold S,

and when not having progressed and exceeded for the following

procedure, it returns to Step S2 (Step S3).

[0088]When vehicles enter in a motor pool even in a front procedure,

can judge that, but. Since it thinks when passing without stopping

then, after judging penetration of vehicles at Step S3, detection and

Measurement Division of the external magnetic field intensity from

the vehicles by each magnetism detecting element are performed

again (step S4), and it compares with total of the absolute value of

data A-B measured last time (Step S5). When this measurement value

is changing from the last measurement value, it judges with vehicles

moving in the inside of a motor pool, and returns to step S4.

[0089]Since it will be either when vehicles stop in a motor pool or a

passing car comes out out of a motor pool as it is if change of

measured value is lost, In order to carry out that judgment which is

the any, in quest of the difference of an initial value and measured-

value-data A-B, it absolute-value-izes separately by all the magnetism

detecting elements, It judges that the total is in the car presence

state which vehicles have stopped in a motor pool when total exceeds

joint threshold S as compared with the above-mentioned

predetermined joint threshold S (that is, it has stopped on the

magnetic sensor 12) (Step S6), and car presence information is taken

out (Step S7). On the other hand, when total of the absolute value of

aforementioned difference A-B is not over joint threshold S, it judges

with the passing car having come out out of the motor pool as it is,

and returns to Step S2.

[0090]Next, detection of the magnetic field of the vehicles by each

magnetism detecting element in order to detect **** of the parked

vehicles, Measure (Step S8) and it absolute-value-izes in quest of the

difference of measurement data A-B and the data of an initial value

separately, When the total is over predetermined joint threshold S,

vehicles are judged continuously to be under parking, It returns to

Step S8, and when it repeated and is not over measurement, vehicles

judge with having left the inside of a motor pool (that is, on the

magnetic sensor 12 was left), take out **** information (Step S10),

return to Step S2, and are again repeated from detection of

penetration of vehicles.

[0091]Thus, based on the detection result of the magnetic field from

vehicles, a stop and **** can be judged during penetration of the

vehicles in a motor pool, and movement, and car presence

information and **** information can be outputted. And the

advantage of the vehicle detecting device of this invention can be

enjoyed, a stop and **** can be correctly judged during penetration of

vehicles, and movement by highly precise and reliable vehicle

detection, and exact car presence information and **** information

can be outputted. Therefore, the vehicle detection system of this

embodiment is effectively [ as management of parking vehicles /

because of management of parking duration, the empty area display

in a scale parking lot, vehicle guiding, etc. ] available.

[0092]

[Effect of the Invention]According to the vehicle detecting method of

this invention, so that clearly from the above explanation to the

ground surface in the band pass of vehicles, or underground. The

magnetic sensor which put in order two or more magnetism detecting

elements which have magnetic field detection sensitivity in the

direction vertical to a ground surface along with the vehicles

longitudinal direction is installed, The external magnetic field intensity

change as on the basis of the state where each of a magnetism

detecting element detects external magnetic field intensity, and there

are no vehicles is measured, Since total of the absolute value of two

or more measurement values of this measuring result was made to

detect vehicles by the judgment of whether to exceed predetermined

joint threshold S, The influence of the zero crossing point which the

magnetic field polarity looked at by distribution of the magnetic field

strength in the case of measuring the magnetic field generated from

a vehicles pars basilaris ossis occipitalis reverses can be avoided, and

highly precise and reliable vehicle detection can be performed.

[0093]While being able to perform reliable vehicle detection with high

degree of accuracy with the vehicle detecting method of this

invention according to the vehicle detecting device of this invention, a

magnetic sensor, For example, it can constitute from small size which

consists of plurality of the small magnetism detecting element

constituted using the magnetic impedance component as a magnetic

sensor of low power consumption, Compared with the equipment

using the conventional loop coil type sensor, prolonged continuous

use is possible, installation can also be easily performed by low cost,

and the use of vehicle detection can be expanded.

[0094]According to the vehicle detection system using the vehicle

detecting device of this invention. By vehicle detection enjoy the

advantage of the vehicle detecting device of this invention, highly

precise and reliable, exact car presence information, **** information

can be outputted and the outstanding effect of being available is

acquired effectively [ because of management of parking duration,

the empty area display in a scale parking lot, vehicle guiding, etc. ] as

management of parking vehicles.

TECHNICAL FIELD

[Field of the Invention]This invention detects the magnetic field

generated from vehicles, such as a car, with a magnetic sensor, and

detects vehicles magnetically, namely, relates to the vehicle

detecting method which detects the existence of vehicles thru/or

passage, a vehicle detecting device, and a vehicle detection system.

PRIOR ART

[Description of the Prior Art]Conventionally, the sensor which detects

vehicles, such as a car, is used in the use of measuring the distinction

of the existence of parking in the managerial system of a motor pool,

and the traffic of the vehicles in a traffic control system.

[0003]Usually, since vehicles, such as a car, are tinged with

magnetism using the metallic material which is easy to be tinged with

magnetism, such as a steel plate, it is detecting the magnetic field

generated from vehicles with a magnetic sensor, and it is possible to

recognize existence of vehicles or passage.

[0004]Conventionally, in the motor pool, the loop coil type magnetic

sensor was buried in the earth, and it has been used for vehicle

detection in it. A loop coil type magnetic sensor is that generate a

magnetic field by an eddy current in the metal part of the body of

vehicles to the alternating current sent through a coil, or the

magnetic field from the body's own magnetization interlinks with a

loop coil, A coil's own inductance changes, it is changed as change of

oscillating frequency or amplitude in a circuit, and vehicle detection is

performed by the existence of the change.

[0005]However, although the loop coil type magnetic sensor is

spreading by detection of vehicles, it has the following problems.

[0006]- Since a loop coil opens an interval a little with vehicles and is

installed, in order to detect the inductance variation in vehicles

existence, there is the necessity of enlarging size of a sensitivity

secured upper coil (about 1mx1m).

[0007]- If metal bodies, such as a steel rod, are in the neighborhood,

S/N cannot be taken enough.

[0008]- Since a loop coil is large and power consumption is large, it is

not fit for continuous energization use.

[0009]- A coil is a size which is about 1mx1m, and the burden of

construction expense is heavy in subterranean installation.

[0010]Then, although the small magnetic sensor was used and the

substitution was considered, When the magnetic field generated from

a vehicles pars basilaris ossis occipitalis was measured, near the zero

crossing point which remarkable unevenness is made to distribution

of magnetic field strength, and magnetic field polarity reverses by the

local magnetization of Body Manufacturing Division article each which

it has, it turned out that the dead point which does not exceed a

threshold required for the judgment of vehicle detection arises.

EFFECT OF THE INVENTION

[Effect of the Invention]According to the vehicle detecting method of

this invention, so that clearly from the above explanation to the

ground surface in the band pass of vehicles, or underground. The

magnetic sensor which put in order two or more magnetism detecting

elements which have magnetic field detection sensitivity in the

direction vertical to a ground surface along with the vehicles

longitudinal direction is installed, The external magnetic field intensity

change as on the basis of the state where each of a magnetism

detecting element detects external magnetic field intensity, and there

are no vehicles is measured, Since total of the absolute value of two

or more measurement values of this measuring result was made to

detect vehicles by the judgment of whether to exceed predetermined

joint threshold S, The influence of the zero crossing point which the

magnetic field polarity looked at by distribution of the magnetic field

strength in the case of measuring the magnetic field generated from

a vehicles pars basilaris ossis occipitalis reverses can be avoided, and

highly precise and reliable vehicle detection can be performed.

[0093]While being able to perform reliable vehicle detection with high

degree of accuracy with the vehicle detecting method of this

invention according to the vehicle detecting device of this invention, a

magnetic sensor, For example, it can constitute from small size which

consists of plurality of the small magnetism detecting element

constituted using the magnetic impedance component as a magnetic

sensor of low power consumption, Compared with the equipment

using the conventional loop coil type sensor, prolonged continuous

use is possible, installation can also be easily performed by low cost,

and the use of vehicle detection can be expanded.

[0094]According to the vehicle detection system using the vehicle

detecting device of this invention. By vehicle detection enjoy the

advantage of the vehicle detecting device of this invention, highly

precise and reliable, exact car presence information, **** information

can be outputted and the outstanding effect of being available is

acquired effectively [ because of management of parking duration,

the empty area display in a scale parking lot, vehicle guiding, etc. ] as

management of parking vehicles.

TECHNICAL PROBLEM

[Problem to be solved by the invention]Then, a reliable vehicle

detecting method in which SUBJECT of this invention can perform

magnetic detection of vehicles with high precision using a magnetic

sensor which consists of two or more small magnetism detecting

elements, And it is in providing a vehicle detection system which is a

vehicle detecting device which performs vehicle detection by the

method, can attain a miniaturization and can be used effective in

management of parking vehicles using a vehicle detecting device of

low power consumption, and this vehicle detecting device.

MEANS

[Means for solving problem]In a vehicle detecting method which

according to this invention detects a magnetic field generated from

vehicles with a magnetic sensor, and detects vehicles magnetically in

order to solve above-mentioned SUBJECT, A magnetic sensor which

put in order two or more magnetism detecting elements which have

magnetic field detection sensitivity in the direction vertical to a

ground surface along with a vehicles longitudinal direction is installed

in a ground surface in a band pass of vehicles, or underground,

External magnetic field intensity change as on the basis of the state

where each of two or more of said magnetism detecting elements

detects external magnetic field intensity, and there are no vehicles

was measured, and a method of detecting vehicles by the judgment

of whether total of an absolute value of two or more measurement

values of this measuring result exceeds predetermined joint threshold

S was adopted.

[0013]According to such a vehicle detecting method, influence of a

zero crossing point which magnetic field polarity looked at by

distribution of magnetic field strength in a case of measuring a

magnetic field generated from a vehicles pars basilaris ossis

occipitalis reverses can be avoided, and highly precise and reliable

vehicle detection can be performed.

[0014]According to this invention, it is a vehicle detecting device

which detects a magnetic field generated from vehicles with a

magnetic sensor, and detects vehicles magnetically, A magnetic

sensor which consists of two or more magnetism detecting elements

arranged so that it may have magnetic field detection sensitivity in

the direction vertical to a ground surface and may rank with a ground

surface in a band pass of vehicles, or underground along with a

vehicles longitudinal direction, A measurement means which

measures each of external magnetic field intensity change as on the

basis of the state where there are no vehicles to each magnetism

detecting element, based on external magnetic field intensity

detected by each of two or more of said magnetism detecting

elements, Total of each absolute value of a measurement value of

external magnetic field intensity change measured by this

measurement means adopted composition of a vehicle detecting

device which has a judging means which judges vehicle detection by

whether predetermined joint threshold S is exceeded.

[0015]While being able to perform reliable vehicle detection with high

degree of accuracy with a vehicle detecting method of this invention

according to such composition, the magnetic sensor can consist of

small size which consists of plurality of a small magnetism detecting

element constituted, for example using a magnetic impedance

component as a magnetic sensor of low power consumption.

[0016]It is a vehicle detection system which performs vehicle

detection using a vehicle detecting device by above-mentioned this

invention according to this invention, A judging means which judges

whether whether vehicles advanced on a magnetic sensor, whether it

stopped on a magnetic sensor based on a decided result of vehicle

detection by a judging means of said vehicle detecting device, and on

a magnetic sensor were left, Car presence information on a purport

that vehicles have stopped on a magnetic sensor based on a decided

result of this judging means, And it has an output means to which

vehicles output **** information on a purport that on a magnetic

sensor was left, and composition of a vehicle detection system which

enabled it to manage parking vehicles with the output of said car

presence information and **** information was adopted.

[0017]According to such composition, an advantage of a vehicle

detecting device of this invention can be enjoyed, exact car presence

information and **** information can be outputted based on highly

precise and reliable vehicle detection, and it can use effective in

management of parking vehicles.

[0018]

[Mode for carrying out the invention]Hereafter, an embodiment of the

invention is described with reference to figures.

[0019][Embodiment of a vehicle detecting method] Drawing 1 - 3

explain the embodiment of the vehicle detecting method by this

invention first.

[0020]In this embodiment, as shown in drawing 1, to the ground

surface 14 in the width which the vehicles (car) 10 pass, or

underground. The magnetic sensor 12 which has arranged two or

more magnetism detecting elements 11A, 11B, and 11C which have

magnetic field detection sensitivity in the direction (Z direction)

vertical to a ground surface so that it may stand in a line along with

the longitudinal direction of the vehicles 10 is installed, and vehicle

detection is performed.

[0021]The external magnetic field intensity change as on the basis of

the state where each magnetism detecting element of the magnetic

sensor 12 detects external magnetic field intensity, and there are no

vehicles 10 is measured, and total of the absolute value of two or

more measured magnetic-field-strength change detects vehicles by

the judgment of whether to exceed a predetermined joint threshold.

[0022]This method was drawn from the following examining results.

[0023]First, on the ground surface 14 in the width which the vehicles

10 pass as shown in drawing 2, The magnetic sensor 12 which

comprised one magnetism detecting element which has magnetic

field detection sensitivity in the Z direction which is a vertical

direction to the ground surface 14 is arranged, the vehicles 10 were

moved on the sensor 12, the magnetic sensor 12 detected external

magnetic field intensity, external magnetic field intensity change was

measured, and the situation of the change was investigated. The

variation of external magnetic field intensity made the measurement

value in the state where there are no vehicles 10 the initial value

used as a standard, and displayed a changed part from it. The

element using the magnetic impedance component mentioned later

as a magnetic sensing device was used for the magnetism detecting

element. Two or more vehicles performed the sampling. Four data

measuring of a characteristic example is shown in drawing 2 (a) - (d)

in it.

[0024]Generally, magnetic field distribution of the cross direction of a

bar magnet has a peak of reverse polarity at both ends of the bar

magnet 16 like drawing 3, and has a tendency which carries out a

zero cross in the center section. On the other hand, it can guess that

the body of a car constitutes a roughly big bar magnet from a

vehicles longitudinal direction from it being in agreement with how of

data measuring of drawing 2 to lengthen the skirt near the both-ends

peak of magnetic field distribution of drawing 3 by (c) and (d),

especially, if it observes near the both ends of a magnetic field

change. However, attitude of a peak has dispersion considerably by

overall magnetic-field-strength distribution, and it does not become a

beautiful form like a bar magnet because local magnetization exists

by part each of a body pars basilaris ossis occipitalis.

[0025]Since detection of vehicles will detect the magnetic field of a

body center section if detection of parking vehicles is taken into

consideration, for example, it observes the magnetic field of the

center of the body by the width of the length of the half of the body

shown in the range of H seal in a figure of each data measuring of

drawing 2. It is because the movement speed of the difference in the

length of each body and the body at the time of Measurement

Division had dispersion that the length of H seal differs.

[0026]Also when unevenness is looked at by magnetic-field-strength

change within the limits of H seal of the data of four examples and a

zero cross exists, the absolute value of a measurement value may go

into the DETTO point on which it is less than threshold s, and one

magnetism detecting element is not enough as it for vehicle detection

at a certain thing.

[0027]When threshold s of one magnetism detecting element

considers the resolution of a magnetism detecting element, and S/N

of a circuit, 0.05 gauss of a minimum is a limit, and considering that a

maximum has about 0.1 gauss vehicles like drawing 2 (c) in the

maximum of the magnetic field change by vehicles, it is difficult to set

up exceeding 0.1 gauss.

[0028]Then, two or more magnetism detecting elements are arranged

along with a vehicles longitudinal direction, and if vehicle detection is

carried out by whether either exceeds threshold s, detection

probability will increase.

[0029]However, in the case of the vehicles of drawing 2 (d), when

four magnetism detecting elements have been arranged to each of

the position corresponding to four points, a in a figure, b, c, and d, the

measurement value by which element will also be less than 0.05

gauss. If such a case is taken into consideration, the device which

raises detection probability further is required.

[0030]Then, the absolute value of the measurement value of two or

more magnetic-field-strength change which detected external

magnetic field intensity by each of two or more magnetism detecting

elements, and was measured is added, The value of the product

which, on the other hand, hung said number (addition numbers of a

measurement value) n of a magnetism detecting element of added

square roots on threshold s at the time of detection by an

independent magnetism detecting element is set up as joint threshold

S, If vehicle detection is judged by whether total of the added result

of said absolute value exceeds joint threshold S, it is detectable by

high probabilities.

[0031]A noise component serves as a mean square to addition of the

output of each magnetism detecting element, and if it is considered

as the noise component of the respectively same size, this will use

that the product of the noise for one element and the square root of

the addition numbers n serves as a noise at the time of combination,

and will try to earn the whole S/N.

[0032]For example, magnetic-field-strength change, a of the data

measuring of the vehicles of drawing 2 (d), b, c, and d, of four points,

It will be 0.03G-0.04G-0.02G-0.03G, and if threshold s of independent

detection is set to 0.05G, when these are added, it will be 0.12G, and

0.05xroot4=0.1 gauss is set to joint threshold S, total of the added

result of an output will exceed joint threshold S, and detection of it

will be attained.

[0033]Therefore, when the magnetic field component of a direction

vertical to the ground surface of the magnetic field generated from

vehicles is detected by two or more Magnetism detecting elementn

and the magnetic-field-strength change by vehicles existence is

measured, It turned out that it is suitable that the total adding each of

the absolute value of magnetic-field-strength change measured based

on the detection result of n magnetism detecting elements of a result

performs vehicle detection by whether joint threshold S as

independent threshold sxrootn is exceeded.

[0034]By the way, since a magnetic-field-detection output may

become near a zero cross with a certain element and total of the

above-mentioned added result may become low when detecting as

mentioned above by two or more magnetism detecting elements, the

method explained below can also be chosen as a method of raising

vehicle detection efficiency further.

[0035]Arrange in descending each absolute value of the

measurement value of the external magnetic field intensity change

from the initial value which detected external magnetic field intensity

by two or more magnetism detecting elements of the magnetic

sensor mentioned above, and was measured, consider it as |deltaH(k)

| (k= 1, 2, ordinal number of --), and Namely, this value, They are

[ threshold s in the case of one magnetism detecting element, and ]

the following expression about said addition numbers n.[0036]

[Mathematical formula 2]

[0037]It compares whether it is alike, it sets, substitutes one by one

from k= 1, and the above-mentioned expression is satisfied, and

when the above-mentioned expression is satisfied, it judges with

having detected vehicles.

[0038]According to this method, vehicle detection efficiency can be

raised by adding the measurement value of two or more external

magnetic field intensity change to descending one by one, and using

for the judgment of vehicle detection.

[0039]In above-mentioned explanation, the "ground surface of

"underground" meaning the inside of those fields including all the

fields that vehicles, such as a floor line in the building of not only the

ground surface of the ground, and the road surface of a road and the

ground surface of an outdoor parking lot but a multi-level car parking

tower, run fields thru/or park" of 14 is natural.

[0040][Embodiment of a vehicle detecting device] Next, the

embodiment of a vehicle detecting device which enforces concretely

the vehicle detecting method mentioned above, and performs vehicle

detection is described.

[0041]First, the magnetism detecting element of the magnetic sensor

used for a vehicle detecting device is explained. Being required of this

magnetism detecting element should be 10 or more milligauss in (1)

magnetic field detection sensitivity.

[0042](2) There is two or more dispersion [ little ] of the performance

of an element for use.

[0043](3) Considering ground surface installation, the height of an

element should be several millimeters.

[0044](4) The detector circuit of an element is excellent in a noise-

proof and temperature characteristics, and be low power

consumption.

[0045]Although there is a flux gate type magnetism detecting

element as what satisfies the conditions of (1), if it is going to raise

detection sensitivity with this element, several 10 mm of the length of

an element will be needed, and it will not be satisfied with it of the

conditions of (3).

[0046]Since it is easy to come out of dispersion in performance, a

problem produces a flux gate type magnetism detecting element also

on condition of (2).

[0047]Then, the magnetism detecting element constituted using a

magnetic impedance component is seemed that it is the optimal by it.

[0048]The magnetic impedance component is indicated by JP,H7-

181239,A and the element body as a magnetic body is constituted

from an amorphous wire or these days by the magnetic thin film etc.

If the high frequency current of an MHz band is impressed to this

element body, according to a magnetic impedance effect, according

to an external magnetic field, the impedance of an element body

changes several 10%, and can detect an external magnetic field using

this.

[0049]The sensitivity of a magnetic impedance component has the

sensitivity of a 10-5 gauss stand, and number milligauss is securable

and it is satisfied also with the practical resolution in the case where it

connects with the circuit of a magnetism detecting element of the

conditions of (1).

[0050]From there being little influence of a demagnetizing field, it is

easy for the length of an element to be 5 mm or less, and the

conditions of (3) are also cleared.

[0051]About dispersion in performance, when supplied with an

amorphous wire, since it is easy to control thickness, dispersion in the

performance resulting from the outside dimension of the magnetic

body of an element body is pressed down, and is satisfied with that

there is little dispersion in the path of a wire, and a magnetic film of

the conditions of (2).

[0052]Although application was considered according to the contents

reported at the society etc. about the magnetic field detection which

uses the Colpitts oscillating circuit about the conditions of (4), there is

a problem practically.

[0053]For example, the application of the magnetic field sensor as an

azimuth sensor is shown by the "amorphous wire MI Colpitts

oscillation type micro magnetic sensor" announced at the 18th

Maganetics Society of Japan academic lecture meeting (14pB-7).

[0054]In the composition of this azimuth sensor, an amorphous wire

is included in a Colpitts type oscillator, and since change of an

external magnetic field turns into change of oscillation amplitude and

it appears, an output is obtained through a detector circuit. While

sending a direct current through the coil directly twisted around the

wire of the element, applying a DC bias magnetic field and making it

operate in the field where sensitivity is high, he is trying to know the

polarity of the direction of north and south.

[0055]However, in minute magnetic field detection, such as

geomagnetism (about 0.3 gauss) by this method. Change of the

output after a detector circuit is as small as several percent, and in

order to treat absolute value change of oscillation amplitude as an

output as it is, sufficient S/N is not obtained from it being easy to be

influenced by change of power supply voltage, the temperature

characteristics of an element, etc. by amplitude fluctuation, and it is

unreliable.

[0056]So, in this embodiment, the circuitry of the magnetism

detecting element shown in drawing 4 was adopted.

[0057]The circuitry of the magnetism detecting element shown in

drawing 4 consists of a Colpitts oscillator, a detector circuit, and a

comparator, the magnetic impedance component 1 mentioned above

is included in the Colpitts oscillator, it direct-winds, or the magnetic

impedance component 1 is approached, and the coil 2 for bias is

formed.

[0058]In this composition, AC bias current Ib is sent through the coil

2, and an about **1-**2 gauss AC bias magnetic field is impressed to

the magnetic impedance component 1. As shown in (a), amplitude

modulation of the oscillation output which appears like the after-

mentioned by this at the A point in a figure of a Colpitts oscillator

according to the intensity of the external magnetic field Hex for

[ which is impressed to the magnetic impedance component 1 ]

detection is carried out, The ripple waveform corresponding to the

bias magnetic field which has the difference of elevation of the

adjacent peak corresponding to the intensity of the external magnetic

field Hex by detecting this in a detector circuit at a B point as shown

in (b) is acquired, By carrying out a party rate with the comparison

voltage Vref which crosses the voltage waveform of said ripple with a

comparator, the Pulse-Density-Modulation output corresponding to

the intensity of the external magnetic field Hex can be obtained at C

point.

[0059]The signal of AC bias current Ib carries out dividing of the clock

from the microcomputer judgment part mentioned later, with a low

pass filter, it may be made into a sine wave or the shape of a

triangular wave, and it may throw it in, or may provide and throw in

an oscillator individually.

[0060]Next, the details of operation of the circuitry of the magnetism

detecting element of drawing 4 mentioned above are explained.

[0061]the characteristic of a magnetic impedance component is

symmetrical with the direction of +- in several gauss to the external

magnetic field Hex, as shown in drawing 5 -- a V character-like

impedance change is shown in general. As shown in drawing 5 (a) as

a principle of operation of the magnetic impedance component 1 of

drawing 4, when there is no external magnetic field, an AC bias

magnetic field is +. - It touches symmetrically, In change of

impedance to it, an impedance change which the difference of

elevation does not have in peaks on a ripple breaks out by a magnetic

field twice the frequency of AC bias.

[0062]Since an AC bias magnetic field and the unsymmetrical

magnetic field which the external magnetic field superimposed will

start the magnetic impedance component 1 like drawing 5 (b) there if

an external magnetic field is impressed to the longitudinal direction of

the magnetic impedance component 1, The impedance change (ripple

waveform) from which the height of a peak differs by turns on an

impedance change arises.

[0063]The ripple waveform in an impedance change as showed the

output after detection of drawing 4 (b) which appeared as amplitude

modulation in the oscillation amplitude characteristic of the Colpitts

oscillator as change of this impedance was shown in drawing 4 (a),

and detected that oscillation output in the detector circuit by drawing

5 (b), and a similar signal are acquired. The size of an external

magnetic field is changed into the output of a digital signal by which

Pulse Density Modulation was carried out by carrying out a party rate

with the comparison voltage Vref which crosses a ripple waveform as

the signal is shown in drawing 6 in a comparator. That is, the Pulse-

Density-Modulation output in which the pulse which is two kinds from

which pulse width differs according to external magnetic field

intensity appears by turns is obtained.

[0064]Thus, pulse width [ of two kinds of pulses ] A which appears by

turns, and B can be measured and evaluated using the timer counter

of a microcomputer, and the digital data in which external magnetic

field intensity is shown can be obtained by asking for the digital data

of difference A-B of pulse width by an operation after that. Although

the measurement data of pulse width to a actual external magnetic

field is shown in drawing 7, in **0.5 gauss shows an almost linear

change. The numerical input value of joint threshold S mentioned

above can be decided by transposing the magnetic field strength of

magnetism detecting element independent threshold s to the math-

processing value of pulse width based on this data, and hanging the

several n square root of a magnetism detecting element on it.

[0065]And the digital data of difference A-B of the pulse width

measured in the state where there are no vehicles, in detection of

vehicles is memorized as data of the initial value of the external

magnetic field intensity used as a standard, Then, the absolute value

of the difference of difference A-B of pulse width and the initial value

according to the measured external magnetic field intensity is

calculated as data corresponding to the absolute value of intensity

change of an external magnetic field, It can ask for total of the data of

said absolute value called for by further two or more magnetism

detecting elements, and the existence of vehicles can be judged by

whether the figure exceeded the numerical value of joint threshold S.

[0066]Next, drawing 8 explains the composition of the vehicle

detecting device using the magnetism detecting element of drawing

4.

[0067]Colpitts oscillator 3 incorporating the magnetic impedance

component 1 which wound the coil 2 for bias which 12 is a magnetic

sensor and was mentioned above in the composition of the vehicle

detecting device shown in drawing 8, They are the marks 11A and

11B about the magnetism detecting element of drawing 4 which

consists of the detector circuit 4 and the comparator 5. -- As shown in

11N, N pieces are provided and it is constituted. Magnetism detecting

elements 11A and 11B -- 11N is arranged so that it may rank with the

ground surface in the band pass of vehicles, or underground along

with the longitudinal direction of vehicles as mentioned above, and

each element can be giving magnetic field detection sensitivity in the

direction vertical to a ground surface.

[0068]18 is a microcomputer judgment part which comprises a

microcomputer, analyzes a Pulse-Density-Modulation output of each

magnetism detecting element of the magnetic sensor 12, and judges

existence of vehicles. The microcomputer judgment part 18, Either

the timer counter 20 which counts pulse width [ of the control section

19 which performs whole control and various data processing, and a

Pulse-Density-Modulation output mentioned above ] A, and B or

magnetism detecting elements 11A-11N are chosen. It consists of the

selector 21 which inputs the output pulse into the timer counter 20

and the clock generator 22, the clock divider 23, the low pass filter

24, and the bias circuit (amplifier) 25.

[0069]Dividing is carried out so that a clock signal which the clock

generator 22 oscillates may become the range of 1 kHz - 100 kHz by

the clock divider 23 in this composition, The low pass filter 24 and the

bias circuit 25 let this signal by which dividing was carried out pass, a

signal of AC bias current of a sine wave or the shape of a triangular

wave is formed, and it is impressed by the coil 2 for bias which are

each magnetism detecting elements 11A-11N of the magnetic sensor

12. A feed zone of this bias current may be provided in the magnetic

sensor 12 side.

[0070]Next, vehicle detection operation by composition of drawing 8

is explained. First, an initial value of external magnetic field intensity

used as a standard for asking for external magnetic field intensity

change in the state where there are no vehicles is measured. For this

reason, with the magnetic sensor 12, a pulse signal which detected

external magnetic field intensity by two or more magnetism detecting

elements 11A-11N, and carried out Pulse Density Modulation is

outputted as mentioned above, and it sends to the selector 21 of the

microcomputer judgment part 18.

[0071]With the command from the control section 19, the selector 21

chooses and sends two kinds of pulses A and B further mentioned

above while it chooses the output pulse signal of two or more

magnetism detecting elements 11A-11N which should be sent to the

timer counter 20 one by one and sends it.

[0072]In the timer counter 20, the pulse width of two kinds of said

pulses A and B of two or more magnetism detecting elements sent

one by one is counted and evaluated, and the data is sent to the

control section 19.

[0073]In the control section 19, difference A-B of the pulse width data

of A pulse and B pulse evaluated with the timer counter 20 is

computed for every magnetism detecting element, and the measured

value of external magnetic field intensity is calculated. The measured

data is recorded on memory storage, such as RAM26 in the control

section 19, as initial value data used as a standard.

[0074]Then, in order to detect vehicles, the detection and the

Measurement Division of external magnetic field intensity by each

magnetism detecting element are performed in the same procedure

as the above, In the control section 19, it asks separately, absolute-

value-izes by using the difference of said measurement data and

initial value data as external magnetic field intensity change data,

and asks for the total, and the existence of vehicles is judged by

whether it is over predetermined joint threshold S which the total

mentioned above. And in the case of the vehicle detection system

mentioned later, car presence information etc. are taken out based on

the result of said judgment.

[0075]In order not to treat the amplitude of a Colpitts oscillator as an

absolute value in the circuitry of the magnetism detecting element of

drawing 4 as an advantage of the equipment of these above

embodiments probably but to treat a changed part of amplitude, a

low change of the frequency by change, temperature characteristics,

etc. of power supply voltage can be disregarded.

[0076]Since the detect output of the external magnetic field intensity

in the magnetic sensor 12 is digitized-output-ized by the Pulse

Density Modulation by a comparator, The magnetic sensor 12 and the

microcomputer judgment part 18 connect two or more magnetic

sensors 12 to the microcomputer judgment part 18, and can carry out

common use of the microcomputer judgment part 18 to two or more

magnetic sensors 12 while also being able to perform installation to

isolate and obtaining the flexibility of installation.

[0077]Since the whole equipment which constituted the magnetism

detecting element very small, could constitute the magnetic sensor

12 small, and includes the microcomputer judgment part 18 can be

made small, The burden of installation cost is small, and it is low

power consumption, and since the prolonged energization use which

was poor at conventional loop coil type equipment is possible, the use

of vehicle detection is expandable.

[0078][Embodiment of a vehicle detection system] Next, drawing 9

and drawing 10 explain the embodiment of the vehicle detection

system for the parking-vehicles management in the motor pool using

the vehicle detecting device of drawing 8 mentioned above. As for

this vehicle detection system, it is needless to say that the portion of

the magnetic sensor 12 is provided in the ground surface of a motor

pool or underground at least, and it carries out of the vehicle

detecting device of drawing 8.

[0079]Drawing 9 is a block diagram showing the functional

composition of the vehicle detection system of this embodiment.

Composition of those other than magnetic sensor 12 is specifically

realized in drawing 9 by the hardware and software of the

microcomputer judgment part 18 of drawing 8.

[0080]In drawing 9, it realizes from the control section 19 of drawing

8, the timer counter 20, and the selector 21, and the measurement

means 27 measures the external magnetic field intensity change as

on the basis of the state where there are no vehicles based on the

detection result of the external magnetic field intensity by the

magnetism detecting elements 11A-11N of the magnetic sensor 12 as

mentioned above. This measurement means 27 has the initial value

memory measure 28 which memorizes the value of the external

magnetic field intensity detected by the magnetism detecting

elements 11A-11N in the state where there are no vehicles as an

initial value used as a standard, and measures external magnetic field

intensity change on the basis of the initial value memorized to this

memory measure 28. The memory measure 28 is specifically

constituted as RAM26 of drawing 8.

[0081]It realizes as a function of the control section 19, and the

vehicle detection judging means 29 judges vehicle detection as

mentioned above based on the measuring result of the measurement

means 27.

[0082]Penetration, a stop, and the **** judging means 30 are realized

as a function of processing of Step S3 of below-mentioned drawing 10

by the control section 19, S6, and S9, Based on the decided result of

the vehicle detection by the vehicle detection judging means 29.

[ whether vehicles advanced into the motor pool, and ] It is judged

whether on whether it advanced on the magnetic sensor 12 formed in

the motor pool, whether whether whether it having stopped in the

motor pool and a motor pool having been left and vehicles stopped on

the magnetic sensor 12, and the magnetic sensor 12 was left.

[0083]Car presence and the **** information output means 31 are

realized as a function of Step S7 of drawing 10 by the control section

19, and processing of S10, Based on the decided result of

penetration, a stop, and the **** judging means 30, vehicles have

stopped at the motor pool, the car presence information on the

purport that vehicles have stopped on the magnetic sensor 12, and

vehicles left the motor pool, namely, vehicles output the ****

information on the purport that on the magnetic sensor 12 was left.

[0084]External magnetic field intensity is detected by the basis of

such composition by the magnetism detecting elements 11A-11N of

the magnetic sensor 12, The external magnetic field intensity change

on the basis of the state where there are no vehicles by the

measurement means 27 based on the detection result is measured,

and the judgment of vehicle detection is performed by the vehicle

detection judging means 29 based on the measuring result. And

based on the decided result of vehicle detection, penetration of the

vehicles in a motor pool, a stop, and **** are judged by the judging

means 30, and car presence information thru/or **** information are

outputted by the output means 31 based on the decided result.

[0085]Next, drawing 10 explains the details of vehicle detection

operation of this system. Drawing 10 is a flow chart which shows the

procedure of the vehicle detection processing by the control section

19 of drawing 8 which realizes each means 27, 29, 30, and 31 of

drawing 9.

[0086]On vehicle detection processing and first in Step S1 of drawing

10 the control section 19, The external magnetic field intensity by

each magnetism detecting element of the magnetic sensor 12 is

made to detect as mentioned above in the state where there are no

vehicles, It asks for the measurement data of the external magnetic

field intensity of A-B mentioned above based on the detection result,

this is set up as initial value data used as the standard which asks for

external magnetic field intensity change, and it memorizes to the

recording equipment of RAM26 grade. Since there are no vehicles into

a motor pool at this time, the control section 19 checks ****

information.

[0087]Next, in order to judge penetration of the vehicles to the

magnetic sensor 12 top formed in penetration of the vehicles into a

motor pool, i.e., the ground surface of a motor pool, and underground,

Detection and Measurement Division of the external magnetic field

intensity from the vehicles by each magnetism detecting element are

performed in the procedure mentioned above (Step S2), It judges with

vehicles having advanced into the motor pool, when it absolute-value-

ized in quest of the difference of each measurement data A-B and

initial value data separately and the total was over predetermined

joint threshold S, and when not having progressed and exceeded for

the following procedure, it returns to Step S2 (Step S3).

[0088]When vehicles enter in a motor pool even in a front procedure,

can judge that, but. Since it thinks when passing without stopping

then, after judging penetration of vehicles at Step S3, detection and

Measurement Division of the external magnetic field intensity from

the vehicles by each magnetism detecting element are performed

again (step S4), and it compares with total of the absolute value of

data A-B measured last time (Step S5). When this measurement value

is changing from the last measurement value, it judges with vehicles

moving in the inside of a motor pool, and returns to step S4.

[0089]Since it will be either when vehicles stop in a motor pool or a

passing car comes out out of a motor pool as it is if change of

measured value is lost, In order to carry out that judgment which is

the any, in quest of the difference of an initial value and measured-

value-data A-B, it absolute-value-izes separately by all the magnetism

detecting elements, It judges that the total is in the car presence

state which vehicles have stopped in a motor pool when total exceeds

joint threshold S as compared with the above-mentioned

predetermined joint threshold S (that is, it has stopped on the

magnetic sensor 12) (Step S6), and car presence information is taken

out (Step S7). On the other hand, when total of the absolute value of

aforementioned difference A-B is not over joint threshold S, it judges

with the passing car having come out out of the motor pool as it is,

and returns to Step S2.

[0090]Next, detection of the magnetic field of the vehicles by each

magnetism detecting element in order to detect **** of the parked

vehicles, Measure (Step S8) and it absolute-value-izes in quest of the

difference of measurement data A-B and the data of an initial value

separately, When the total is over predetermined joint threshold S,

vehicles are judged continuously to be under parking, It returns to

Step S8, and when it repeated and is not over measurement, vehicles

judge with having left the inside of a motor pool (that is, on the

magnetic sensor 12 was left), take out **** information (Step S10),

return to Step S2, and are again repeated from detection of

penetration of vehicles.

[0091]Thus, based on the detection result of the magnetic field from

vehicles, a stop and **** can be judged during penetration of the

vehicles in a motor pool, and movement, and car presence

information and **** information can be outputted. And the

advantage of the vehicle detecting device of this invention can be

enjoyed, a stop and **** can be correctly judged during penetration of

vehicles, and movement by highly precise and reliable vehicle

detection, and exact car presence information and **** information

can be outputted. Therefore, the vehicle detection system of this

embodiment is effectively [ as management of parking vehicles /

because of management of parking duration, the empty area display

in a scale parking lot, vehicle guiding, etc. ] available.

DESCRIPTION OF DRAWINGS

[Brief Description of the Drawings]

[Drawing 1]It is an explanatory view showing the arrangement and

the direction of magnetic field detection over the vehicles of the

magnetism detecting element of the magnetic sensor in the

embodiment of the vehicle detecting method by this invention.

[Drawing 2]They are the explanatory view and graph charts showing

the situation of the external magnetic field intensity change by

movement of the vehicles detected with the magnetic sensor which

comprised one magnetism detecting element.

[Drawing 3]They are the explanatory view and graph charts showing

the magnetic field distribution of the cross direction of a bar magnet.

[Drawing 4]It is a circuit diagram showing the circuitry of the

magnetism detecting element of the magnetic sensor used for the

embodiment of the vehicle detecting device by this invention.

[Drawing 5]They are graph charts showing the impedance change by

the AC bias magnetic field and external magnetic field of a magnetic

impedance component in drawing 4.

[Drawing 6]It is a wave form chart showing the bias current Ib in

drawing 4, the after-detection output of a detector circuit, and a

comparator output.

[Drawing 7]They are graph charts showing the pulse width and the

count number of a difference of the pulse which is two kinds from

which the pulse width of the comparator output to an external

magnetic field differs.

[Drawing 8]It is a block diagram showing the composition of the

embodiment of a vehicle detecting device.

[Drawing 9]It is a block diagram showing the functional composition

of the embodiment of the vehicle detection system by this invention.

[Drawing 10]It is a flow chart figure showing the vehicle detection

procedure in the vehicle detection system.

[Explanations of letters or numerals]

1 A magnetic impedance component

2 The coil for bias

3 Colpitts oscillator

4 Detector circuit

5 Comparator

10 Vehicles

11A-11N Magnetism detecting element

12 Magnetic sensor

14 Ground surface

18 Microcomputer judgment part

19 Control section

20 Timer counter

21 Selector

22 Clock generator

23 Clock divider

24 Low pass filter

25 Bias circuit

26 RAM

27 The measurement means of external magnetic field intensity

change

28 Initial value memory measure

29 Vehicle detection judging means

30 Penetration, a stop, and a **** judging means

31 Car presence and a **** information output means

DRAWINGS

[Drawing 1]

[Drawing 2]

[Drawing 7]

[Drawing 3]

[Drawing 5]

[Drawing 4]

[Drawing 6]

[Drawing 8]

[Drawing 9]

[Drawing 10]