SEMINAR TOPIC:SEMINAR TOPIC:TOUCH SCREEN SENSORTOUCH SCREEN SENSOR

COARSE FACULTY:COARSE FACULTY:SUBMITTED BY:SUBMITTED BY:DR. SUGUMARANDR. SUGUMARAN AKSHAY AKSHAY DHOLEDHOLE(SMBS)(SMBS) (13MMT1013)(13MMT1013)

INTRODUCTION HISTORY FUNCTIONS WORKING DIFFRENT TOUCH SCREEN

TECHNOLOGIES APPLICATION CONCLUSION

A touch screen is a computer display screen that is sensitive to human touchsensitive to human touch, allowing a user to interact with the computer by touching pictures or words on the screen.

A touch screen is an input device that allows users to operate a PC by simply touching the display screen which has a sensitive glass overlay placed on it .

A touch screen accepts direct onscreen inputs.

In 1971, the first "touch sensor" was developed by Doctor Sam Hurst (founder of Elographics) while he was an instructor at the University of Kentucky.

The University of Kentucky Research Foundation named it as “Elograph”.

The "Elograph" was not transparent like modern touch screens.

In 1974, the first true touch screen incorporating a transparent surface came.

Pressure sensitive activation-by finger or stylus.

Emulates mouse functions-click, double click, & drag.

Touch screen & mouse can be used concurrently.

Durable & scratch resistant coated surface. Compatible with OS-Windows

XP,7,8,Macintosh,Linux.

A basic touch screen has three main components:

touch sensor controller software driver

A touch screen sensor is a clear glass panel with a touch responsive surface which is placed over a display screen.

The sensor generally has an electrical current or signal going through it and touching the screen causes a voltage or signal change. This voltage change is used to determine the location of the touch to the screen.

The controller is a small PC card that connects between the touch sensor and the PC.

It takes information from the touch sensor and translates it into information that PC can understand.

The driver is a software that allows the touch screen and computer to work together.

It tells the operating system how to interpret the touch event information that is sent from the controller.

Most touch screen drivers today are mouse-emulation type driversmouse-emulation type drivers. This makes touching the screen the same as clicking your mouse at the same location on the screen.

There are several principal ways to build a touch screen:

In the most popular techniques, the capacitive or resistive approach, manufactures coat the screen with a thin, transparent metallic layer.

When a user touches the surface, the system records the change in the electrical current that flows through the display.

Dispersive-signal technology which 3M created in 2002, measures the piezoelectric effect — the voltage generated when mechanical force is applied to a material — that occurs chemically when a strengthened glass substrate is touched.

WORKINGWORKING

RESISTIVECAPACITIVESURFACE WAVEINFRAREDDISPERSIVE SIGNAL

TECHNOLOGY

Polyester Film . Top Resistive Layer. Conductive Transparent Metal

Coating. Bottom Resistive Layer . Insulating Dots . Glass Substrate

Pressing the flexible top sheet creates electrical contact with the coating on the glass.

The touch screen controller gets the alternating voltages between the two layers and converts them into the digital X and Y coordinates of the activated area.

Can be activated with any device Low cost solution Low power consumption

Poorer durability compared to other technologies

Very short life, especially considering cosmetic wear

In the capacitive system, a layer that stores electrical charge is placed on the glass panel.

When a user touches, some of the charge is transferred to the user, so the charge on the capacitive layer decreases.

This decrease is measured in electrodes located at each corner of the monitor.

The computer then calculates the coordinates, from the relative differences in charge at each corner.

A finger touch draws current from each corner.

Then the controller measures the ratio of the current flow from the corners and calculates the touch location

ADVANTAGESADVANTAGES

  More durable than resistive

Higher transmittance than resistive

DISADVANTAGESDISADVANTAGES

    Accepts input from finger only.

                            Accuracy is

dependent on capacitance of person

It has a transmitting and receiving transducers for both the X and Y axes.

The touchscreen controller sends a five-megahertz electrical signal to the transmitting transducer, which converts the signal into ultrasonic waves within the glass.

These waves are directed across the front

surface of the touchscreen by an array of reflectors.

Reflectors on the opposite side gather and direct the waves to the receiving transducer, which reconverts them into an electrical signal.

When you touch the screen, you absorb a portion of the wave travelling across it.

The receivers can detect a drop in amplitude and thus coordinate is calculated.

ADVANTAGESADVANTAGES

    Very high transmittance

   Very high durability  

DISADVANTAGESDISADVANTAGES

  Requires “soft” input device

Surface obstructions can cause a false touch

IR makes use of a “frame” around the perimeter of the display. On two sides there are closely spaced IR LEDs and on the opposing two sides there are matching photo transistors.

The LEDs are turned on in sequence and the signal is read from the matching transistor. If no signal is read, then that indicates a blocked IR beam, meaning a touch.

ADVANTAGESADVANTAGES

Highest quality Highest quality of underlying of underlying image image

Very high Very high transmittance transmittance   

       Very high Very high

durability and durability and reliabilityreliability

DISADVANTAGESDISADVANTAGES

Lower resolution Lower resolution than other than other technologies technologies

       Surface Surface obstructions can obstructions can cause a false cause a false touch touch

Technology Capacitive SAW Infrared Resistive

Transparence Very good >92% Very good >92% Very good >92% 75%~85%

Resolution Good Good Limited due tospacing of IRsensors

good

SurfaceContaminants/durability

Resistant tomoisture andother surfacecontaminants

Adversely affected bymoisture orSurfacecontaminants

Potential forFalse activationor dead zonesFrom SurfaceContaminants

Unaffected by Surfacecontaminants.Polyester topsheet is easilyscratched

Sensor substrate Glass with ITO coating

Glass with ITO coating

Any substrate Polyester top sheet, glasssubstrate withITO coating

Display size 8.4"-21" 10.4"-30" 10.4"-60" up to 19"

Touch method Human touch finger, gloved

hand or soft tip Can use any pointing device

Can use any pointing device

User friendly. Fast response. Error free input. Easy to install. Use finger, fingernail, gloved hand, stylus or

any soft-tip pointer to operate. Easy to clean and maintain. Compatible with Windows, Macintosh and

Linux. Does not interfere mouse and keyboard

function. Make computing easy, powerful and fun.

ADVANTAGES:ADVANTAGES:

Finger stress: Stress on human fingers when used for more than a few minutes at a time. (for example, ATMs).

Fingerprints: Touchscreens can suffer from the problem of fingerprints on the display.

User has to sit closer to the screen as compared to external keyboard.

The screen may be covered more by using hand.

DISADVANTAGES:DISADVANTAGES:

This is the recent most technology, introduced in 2002.

It uses sensors to detect the mechanical (vibrational)energy in the glass that occur due to a touch.

Complex algorithms then interpret this information and provide the actual location of the touch.

PUBLIC ACCESS:  Mobile Phones  Library resource guides  Computers  Public Transportation Schedule /

Status Airport terminal passenger internet

and email systems Automated travel and entertainment

ticket dispensers Shopping mall directory

COMMERICAL Gas stations  Point of sales Restaurants  Grocery stores Hospital and hotel directories (check-in,

registration)  Banks and Financial Reporting  Bank cash advance and teller machines

Touch screens, touch panels or touch screen panels are display overlays which have the ability to display and receive information on the same screen.

Touch screens also have assisted in recent changes in the PDAs, making these devices more usable.

In future there is no usage of mouse and keyboards as they will be replaced by touch screens.