SASE Proximity Sensor - Ver 2.0

CONFIDENTIAL

OMRON ASIA PACIFIC PTE LTD

1

OMRON

Kinsetsu Sensa Gijutsu Shiryo

Proximity Sensor Technical InformationVer 2.0 – Jun 2007

CONFIDENTIAL


2

OMRON

1. What is a Proximity Sensor?

2. Types of Proximity Sensors

3. Classification of Proximity Sensors

4. Inductive Proximity Sensor

4.1 Basic principles

4.2 Features

5. Effects of target objects on sensing distance

6. How to select the appropriate Proximity Sensor?

7. Proximity Sensors Terminology

Content

CONFIDENTIAL


3

OMRON1. What is a Proximity Sensor?

A proximity sensor detects the approach of an object without making a contact, making use of changes in a magnetic/electric field.

Spider Web Analogy

CONFIDENTIAL


4

OMRON2. Types of Proximity Sensor

Oscillation

‘Eddy’ Current

Magnetic Field Sensor

Lead Switch

PermanentMagnet

Open/close lead switch by permanent magnet

Open/close element

Sensing object

Changes in capacitance between electrodes and earth

Electromagnetic Field Type

Proximity Sensors make use of (1) Electric Field or (2) Magnetic Field to do detection. Magnetic Field are less commonly used. There are 2 different types of Electric Field: Electromagnetic Field & Electro-static Field.

Electro-static Field Type

Magnetic Field Type

Commonly Used!

CONFIDENTIAL


5

OMRON

1. By Detection Method

2. By Coil Enclosure

3. By Sensing Head

4. By Sensing Amplifier

5. By Output Mode

6. By Application


CONFIDENTIAL


6

OMRON

E2EV

E2EY

E2E

E2K-L

Inductive Type

1. By Detection Method

E2K-C

Capacitive Type


CONFIDENTIAL


7

OMRON

2. By Coil Enclosure

Shorter sensing distance Not affected by surrounding metal

Longer sensing distance Affected by surrounding metal as electromagnetic field flows backward to the sensor


Shielded Type (Flushed-mounted)

Unshielded Type(Non-flushed mounted)

E.g. E2E-X2ME1-M1 E.g. E2E-X5ME1-M1

CONFIDENTIAL


8

OMRON

3. By Sensing Head

Shape Sensor Face Product Model Applications

Cylindrical Type

PBT E2A

E2E

General purpose

Fluoro-resin E2EQ

E2FQ

Anti-spatter for Automotive

Stainless Steel

E2EH High temp (up to 120C) for Food & Beverage

E2FM Stainless steel housing for harsh environments

Rectangular Type TL-N General purpose

Flat Type E2J

E2C

Flat head for robots or mounting constraint

NEW


CONFIDENTIAL


9

OMRON

4. By Sensing Amplifier

E2C-T

Amplifier Product Model Advantages

Built-in Amplifier

Easy to use Easy to mount

Separate Amplifier

Compact head for space constraint machines Teaching functions available for more precise detection

In-cable Amplifier

Compact head for space constraint machines

E2C-EDA

E2E TL-N TL-W

NEW

E2EC-QC / E2EC-MC


E2EC

NEW

CONFIDENTIAL


10

OMRON

DC/AC Output Circuit

with Polarity

without polarity

NO/NC selected by connections

AC/DC

2- W

ire

Typ

e

DC

AC

5. By Output Mode


CONFIDENTIAL


11

OMRON

DC/AC Output Type Circuit

DC

NPN

NPN Open Collector

PNP

PNP Open Collector

3 -W

ire

Typ

e


CONFIDENTIAL


12

OMRON3. Classification of Proximity Sensors

CONFIDENTIAL


13

OMRON

6. By Application

Product Model Application Key features

E2FM

E2FM-Q (Flourine-coating)

Harsh environments where grinding, collision & mechanical collision are highly prone

• 0.8mm thickness SUS303 housing• Chip-immunity function• Chemical and detergent resistance

E2EH-X Food & Beverage, High-temperature wash down areas

• SUS316L housing • Heat resistance up to 120C

E2C-H High-temperature environments

Heat resistance up to 200C

E2E-X-U

E2E-X-U-M1GJ

Machine oil, cutting oil environments

• PUR cable (Frame proof, lead free and halogen free)• Smart click connector (E2E-X-U-M1GJ)

E2AX Petrochemical plants • ATEX Group II CAT 3D cert.• IP65 complied

E2AW Welding plants,

Automotive

• High temp. abrasion-resistant coating on sensing face

E2AU Mobile platforms • Cable breakage resistance• High resistance to cyclic and rapid temperature change

NEW

NEW

NEW


CONFIDENTIAL


14

OMRON

Application Example

Injection mold closure detection

Plastic injection machines can generate a lot of heat due to energy dissipations from molten materials. In this application, the inductive proximity sensor must be resistant to high temperature.

E2C-H (up to 200C) E2EH (Up to 120 C)

Plastic Injection Machine

Recommendations:

NEW


CONFIDENTIAL


15

OMRON

4. Inductive Proximity Sensor

CONFIDENTIAL


16

OMRON

LC Amplitude

Detectingcircuit

Outputcircuit

Target Oscillation circuit

High-frequency magnetic field

4.1 Basic Principles of Inductive Proximity Sensor

CONFIDENTIAL


17

OMRON

Metal object

Approach of object

Sensor

Amplitude of oscillation

Operating level

Output voltage

Switching circuit

Releasing level

Off

ON

Off


CONFIDENTIAL


18

OMRON

Oscillating circuit

Object (metal)

Sensing coil in the proximity sensor

The detection coil located at the front end of the sensor produces a high-frequency magnetic field as shown in the picture.

When an object (metallic) approaches this magnetic field, an induction current(eddy current) flows in the target due to electromagnetic induction. As the target approaches the sensor, the induction current flow increases, which causes the load on the oscillation circuit to increase. Then, oscillation attenuates or stops. The sensor detects this change in the oscillation status with the amplitude detecting circuit, and outputs a detection signal

The degree of the change in the oscillation amplitude varies depending on the target metal type, and therefore the detecting distance also varies depending on the target metal type

Principle of operation


CONFIDENTIAL


19

OMRON4.1 Basic Principles of Inductive Proximity Sensor

CONFIDENTIAL


20

OMRON4.1 Basic Principles of Inductive Proximity Sensor

CONFIDENTIAL


21

OMRON

Operating principle of all-metal Prox. (E2EV type)

LC Frequency

Comparisoncircuit

Outputcircuit



Detects all kinds of metal at the same distance. The all-metal type is basically included in the high-frequency oscillation

type. The all-metal type incorporates an oscillation circuit in which energy loss caused by the induction current(eddy current) flowing in the target affects the change of the oscillation frequency. When a target approaches the sensor, the oscillation frequency increases regardless of the metal type. The sensor detects this change and outputs a detection signal.


CONFIDENTIAL


22

OMRON

Operating principle of non-ferrous metal Prox. (E2CY, E2EY type)

LC Frequency

Comparisoncircuit

Outputcircuit



The nonferrous-metal type is basically included in the high-frequency oscillation type. The nonferrous-metal type incorporates an oscillation circuit in which energy loss caused by the induction current flowing in the target affects the change of the oscillation frequency. When a nonferrous-metal target such as aluminum or copper approaches the sensor, the oscillation frequency increases. On the other hand, when a ferrous-metal target such as iron approaches the sensor, the oscillation frequency decreases. When the oscillation frequency becomes higher than the reference frequency, the sensor outputs a detection signal.


CONFIDENTIAL


23

OMRON

1. Non-contact detection

2. Only detect metals

3. Detecting distances are small (0 to 30mm typ.)

4. Can be used in severe environment (e.g. dusty environment)

5. High response speed

6. Compact sensor head for installation flexibility

Iron Copper Brass

4.2 Features of Inductive Proximity Sensor

CONFIDENTIAL


24

OMRON

1. Material of the object

2. Size of the object

3. Thickness of the object

4. Effects of plating

Factors that affect sensing distance:

5. Effect of Target Object on Sensing Distance

CONFIDENTIAL


25

OMRON

Steel

SUS

Brass

Aluminum

Copper

100%

70%

40%

30%

28%


Of Rated SD

Ferrous

Non-Ferrous


CONFIDENTIAL


26

OMRON

The detection distance varies greatly depending on the material of the detecting object

Magnetic material or ferrous metal such as iron, SUS have longer sensing distance, while non magnetic metals or non-ferrous metal have shorter sensing distance

Side length (one side) of sensing object d (mm)

E2E-X1R5E

Sen

sin

g d

ista

nce

X (

mm

)



CONFIDENTIAL


27

OMRON

Iron

SUS

BrassAluminum

Copper

Conductivity of test object

Sensing distance X mm

The higher the conductivity, lower the magnetic inductance Non ferrous metals are more conductive then ferrous metals. Hence, it offers lower resistance to the eddy current, resulting in that the magnetic field penetrates deep inside the metal Less flux appears out, and hence the sensing distance gets smaller

Sensing distance

Non-ferrous metal, such as Aluminum, Copper

Ferrous metal, such as Iron, SUS

Object

Sensor head

Object

Sensor head



CONFIDENTIAL


28

OMRON

2. Size of the object

Sensing distance becomes short Stability

Side length(one side)Of sensing object :d(mm)

If the object gets smaller then the standard test object, the detection distance decreases


CONFIDENTIAL


29

OMRON

3. Thickness of the object

The thickness of magnetic metal (iron, nickel, SUS etc.) must be 1mm or more.

When the thickness of a non-ferrous metal is 0.01mm or less, it has a detection distance equivalent to that of a target of ferrous metal.

For Aluminum foil with thickness of 10m, the resistance offered to the eddy current would be higher than a 10mm thick aluminum sheet.

The flux cannot penetrate deep inside the foil and will confine mostly on the surface of the object => Hence, longer sensing distance.

Thickness of sensing object : t (mm)

Sen

sin

g d

ista

nce

X (

mm

)

30

30t

Object

Sensor head

10m


CONFIDENTIAL


30

OMRON

4. Effects of plating

Thickness and base material of plating type Steel (%) Brass (%)

No Plating 100 100

Zn 5 to 15m 90 to 120 95 to 105

Cd 5 to 15m 100 to 110 95 to 105

Ag 5 to 15m 60 to 90 85 to 100

Cu 10 to 20 m 70 to 90 95 to 105

Cu 5 to 15 m --- 95 to 105

Cu (5 to 15 m) + Ni (10 to 20 m) 70 to 95 ---

Cu (5 to 10 m) + Ni (10m) + Cr (0.3 m) 70 to 95 ---

Note: % is with respect to non-plated detection distance

If the object is plated, the detection distance will be affected.


CONFIDENTIAL


31

OMRON

1. Target Materials

- Sensing Object => Determine inductive/capacitive type

- Sensing Distance => Determine barrel size

- Direction of movement of objects

2. Environment

- Presence of metallic chips, sputter or filings?

- Presence of cutting fluids, chemicals, detergents or oil?

- High temperature?

3. Mounting restrictions

- Any installation constraints?

4. Other requirements?

- Output type, shielded/unshielded, separate amplifier & etc…


CONFIDENTIAL


32

OMRON

Parameters Description Product

AC/DC

DC

24 to 240Vdc, 48 to 240Vac 12 to 24Vdc

E2E

E2E other models

Temperature -25 to 70C -10 to 200C 0 to 120C

General

E2C-H, E2C-EM02H

E2EH-X (DC 3-wire)

Body material One piece SUS housing PBT sensor head Teflon coated

E2FM

E2EH-X (most models)

E2FQ

NEW

NEW


CONFIDENTIAL


33

OMRON

Please consider following points while selecting and installing a Prox. Sensor.

Detection object and activation condition of proximity sensor

Specific conditions of

object

Direction of movement of

object

Peripheral metal

Sensing distance

Material, size, shape,

existence of plating, etc.

Transit interval, speed,

existence of vibration, etc.

Material, distance to detector,

orientation, etc.

Permitted deviation

error in transit point, etc.

Detection (setting) distance, shape of sensor detector (square rod type, cylinder type, through-type, slot type). Effect of peripheral metal (shielded type, non-shielded type), response speed (response frequency). Effect of temperature, effect of voltage …


CONFIDENTIAL


34

OMRON


Load

Resistance load – Non-contact control system

Inductance load – relay, solenoid, etc.

• Constant current value, surge current value

• Operation, reset voltage (current)

Lamp load

• Constant current surge

Open/close frequency

Electrical Conditions:

Power Supply

Direct current (voltage change value, current capacity value)

Alternating current (voltage change value, frequency, etc.)

Need for S3D2 controller

Selecting the voltage type

- DC type

- DC type + S3D2 controller

- AC type


CONFIDENTIAL


35

OMRON


Environmental Conditions:

The environment tolerance characteristics of the proximity sensor are better than other models of sensors, however, investigate well before using in harsh temperature conditions or in special atmospheres.

Temperature and humidity

Atmosphere Need for water resistance or oil resistance, need for explosion proof type

Water, oil, iron powder, and other special chemicals

High value or low value, existence of direct sunlight, etc.

Temperature effects, high-temperature use, low temperature use, need for shade, etc.

Vibration and shock

Need for solidarity, mounting method

Size, duration


CONFIDENTIAL


36

OMRON


Environmental Conditions:- Water Resistance

Do not use in water, rain, or outside.

- Ambient Conditions

In order to maintain reliability of operation, do not use outside the specified temperature range or in outdoor conditions. The proximity sensor has a water resistant structure, however, it must be covered to prevent direct contact with water or water-soluble shaving oil. Do not use in atmospheres with chemicals, in particular strong alkaline or acid (nitric acid, chromic acid, or hot concentrated sulfuric acid).

- Explosive atmospheres

Cannot be used in atmospheres where there is a danger of explosion. In this case, it is recommended to use an explosion-proof sensor.


CONFIDENTIAL


37

OMRON

Please consider following points while selecting and installing a Prox. Sensor .

Mounting Conditions:

When deciding the mounting method, take into consideration not only restrictions due to the mechanical device, but also ease of maintenance and inspection, and interference between sensors.

Mounting Procedure

Existence of mounting clamps

Direct mounting

- Secured with bolts or screws

Ease of maintenance and inspection

Mounting spaceFixed location

Wiring method, existence of inductance surges

Wires

- Wire type, length, oil resistance cable

- Shielded cable

- Robot cable, etc.

Conduit cable, duct cable

Direct pull-out, terminal wiring

Ease of maintenance and inspection

Connections


CONFIDENTIAL


38

OMRON

Please consider following points while selecting and installing a Prox. Sensor. .

Effect of external electromagnetic field

- The effect within a direct magnetic field is 20 mT. Do not use a level higher than 20 mT.

- Sudden changes in the direct current magnetic field may cause incorrect operation. Do not use for applications that involve turning the direct current electromagnet on and off.

- Do not place a transceiver near the proximity sensor on its wiring, as this may cause incorrect operation.


CONFIDENTIAL


39

OMRON

Mutual Interference Occurs when more than 2 pieces of sensors are installed facing each other or side by

side, causing the output to be unstable. To avoid interference, it is possible to:

Separate the sensors by a minimum distance. Use one with standard oscillation and the other with different freq. alternately.

Sensor Installation Consideration

Points to note

For E2E-X, min. distance between sensors


CONFIDENTIAL


40

OMRON

Detecting distanceThe distance from the detecting surface of a sensor head to the point where a standard target approaching the sensor head is first detected

7. Proximity Sensor Terminology

CONFIDENTIAL


41

OMRON

Setting Distance The distance from the reference surface, which allows stable use including the effects of temperature and voltage, to the (standard) test object passage position. This is approximately 70% to 80% of the normal (rated) detection distance.


CONFIDENTIAL


42

OMRON

HysteresisThe difference between the reset distance and the detecting distance using a standard object. The reset distance refers to the distance from the detecting surface of a sensor head to the point at which the sensor resets for subsequent detection.


CONFIDENTIAL


43

OMRON

Standard Target A target determined as standard according to the shape , size, and material, that is used to obtain the specification of a sensor.


CONFIDENTIAL


44

OMRON

Shielded Type The sensing coil is encased in a metal shielding. The magnetic flux is concentrated in front of the sensor because the sides of the sensor coil are covered with metal case. Shielded type is less affected by surrounding metal. And can be embedded in a metal base.


CONFIDENTIAL


45

OMRON

Non- shielded Type The sensing coil is not metal-shielded. The magnetic flux is spread in front as well all sides of the sensor, as the sensor coil is not covered by any metal case. This type provides a longer detecting distance, compared to a shielded type of the same size.

Since, non-shielded type is easily affected by the surrounding metal, and therefore no object other then the target must be present around the tip of the sensor head.


CONFIDENTIAL


46

OMRON

Effects of surrounding metal The existence of metal objects other then the detection object near the detection surface of the proximity sensor will affect its detection performance. There could be increase in the activation distance, degrade temperature characteristics, and cause reset failure. Especially while using a non-shielded type as it requires more clearance from the surrounding metal. Provide a minimum distance as advised in the catalog for the particular model. The values in the table are for general guideline only, as it is calculated for the nuts that accompany each model. Changing the nut material will change the effect of peripheral metals.

0

0


CONFIDENTIAL


47

OMRON

2-wire Proximity Sensors

Point of 2-wire Prox. Sensor(1) Unlike , 3-wire output there is no output cord (black). The output load

is directly connected in series with the sensor. There are two kinds, polarity type and non-polarity type.

(2) Advantage points :(a) Easy wiring(b) In case of many sensors connected in a production machine, if

accidentally, one of the sensor is shorted it is easier to investigate the failed sensor.


CONFIDENTIAL


48

OMRON

2-wire Proximity Sensors Connection Diagram

Power Supply 24Vdc 1

2

COM

COM

DC24V 6mA

PLC

Common

Input

Sensor

Brwn

Blue


CONFIDENTIAL


49

OMRON

+ _+ _

Load

Example : In an automobile production line, there were many 3-wire prox. Sensors installed . One of the sensors became short circuited due to sputter from the welding. The power supply that was supplying power to all the sensors tripped. It took them hours to locate the exact the sensor that was short circuited. Because, as soon as the power ON, it will trip, and it is difficult to investigate where the fault location is.

But, if 2-wire Prox. Sensor would have been used, then because of the load resistance, power would not trip. Only, the short circuited sensor would stop functioning. That would then make it easy to locate the faulty sensor.

2-wire type : A real life example

Power Power


CONFIDENTIAL


50

OMRON

2-wire Proximity Sensors : Caution Points

(1) Surge ProtectionAlthough the proximity sensor has a surge absorption circuit, if there is a device (motor, welder, etc.) that causes large surges near the proximity sensor, insert a surge protector in the source of the surges.


CONFIDENTIAL


51

OMRON

(2) Residual Voltage : The impedance of the 2-wire type proximity sensor’s circuit, when output is ON, produces a voltage which is the difference of the voltage across the 2 wires connected to it. (V1, 0V). This means that the voltage across the load (V2) is equal to the supply voltage minus V1 (V2=Vs-V1). Make sure that V2 is greater than the operating voltage of the load. (Refer to the characteristic chart “Residual voltage”)


Proximity Sensor V1

Load

V2 Power Supply

Vs

Load Voltage V2 = Vs – V1


CONFIDENTIAL


52

OMRON

(2) Leakage current : With a 2-wire proximity sensor, a small amount of current flows (leakage current) to keep the circuit operating even when the sensor is turned OFF. (Refer to the “leakage current characteristic graph” . Because of this current, a low voltage remains on the load, sometimes preventing the load from properly resetting. Before operation, check that the residual voltage is lower than the reset voltage of the load. )



CONFIDENTIAL


53

OMRON

When load current is low:When the load current is less than 10mA, connect a bleeder resistor to give the sensor 5mA or more load current. Make sure the residual voltage is less than the reset voltage of the load.



CONFIDENTIAL


54

OMRON7. Proximity Sensor Terminology


CONFIDENTIAL


55

OMRON

Response Time

- t1 : The interval from the point when the standard test object moves into the detection range of the sensor to the point when the output turns ON after the sensor activates.

- t2 : The interval from when the standard test object moves out of the sensor detection range to when the sensor output turns OFF.


CONFIDENTIAL


56

OMRON

Response Frequency

Response Frequency f (Hz) = 1 / (t1 + t2)

- The number of detection repetitions that can be output per seconds when the standard test object is repeatedly brought into proximity.

- See the accompanying diagram for the measuring methods.


CONFIDENTIAL


57

OMRON

Horizontal detection distance Detection area diagram

How Detection Distance is expressed

In the measurement of detection distance of proximity sensor, the reference position and the direction of approach of the detected object are determined as follow.

Expressed as the measured distance from the reference axis when the standard test object is moved parallel to the reference surface (detection surface).

This distance varies depending on the transit position (distance from the reference surface), thus it can be expressed as an operation point track.


CONFIDENTIAL


58

OMRON

Perpendicular detection distance



Expressed as the measured distance from the reference surface when the standard test object is made to approach from the radial direction (perpendicular to the detection surface).


CONFIDENTIAL


59

OMRON

Slot Type

The slot type is frequently used by inserting a thin metal plate through the slot, and thus the insertion distance from the reference surface is measured as shown in the diagram.




Documents

SASE Proximity Sensor - Ver 2.0