Efforts by:

Ankit Puri

B-Tech ECE

Presentation On Touchscreen

OVERVIEW Introduction Multi Point Touch Touchscreen Technologies Comparison Of Technologies Conclusion Future Technologies

INTRODUCTION A touchscreen is an electronic visual display that can

detect the presence and location of a touch within the display area.

Touchscreens can sense by touching the display of device by finger, hand or devices such as a stylus.

HISTORY Touchscreen emerged from academic and

corporate research lab in late 1960’s. One of the first places where they gained some

visibility was in the learning terminal of a computer-assisted that came out in 1972 as part of the PLATO project.

The HP-150 from 1983 was probably the world's earliest commercial touchscreen computer.

It doesn't actually have a touchscreen in the strict sense, but a 9" Sony CRT surrounded by infrared transmitters and receivers which detect the position of any non-transparent object on the screen.

MULTI-POINT TOUCH

Until the early 1980s, most consumer

touchscreens could only sense one point of

contact at a time, and few have had the

capability to sense how hard one is touching.

The development of multi-point touch

facilitated the tracking of more

then one finger on a screen

With the influence of multi touch the touch

screen market for mobile devices is

projected to produce 15 Billon $ in 2011

TOUCHSCREEN TECHNOLOGIES

Resistive Touchscreen

Capacitive Touchscreen

Surface Acoustic Wave Touchscreen

Infrared Based Touchscreen

RESISTIVE

TOUCHSCREEN

TECHNOLOGY

WORKING OF RESISTIVE SENSORS

Resistive touchscreen monitor is composed of

Flexible Top Layer ( Plastic Film )

Rigid Bottom Layer ( Substrate )

Insulating Dots ( Spacer ) Top and Bottom Layers are transparent. Pressure over top layer makes the electric contact between

resistive bottom layer. With the help of controller alternative voltages are converted into

digital X Y co-ordinates and mark the position of touch. Resistive technology gives only 75% optical transparency and the

fact that sharp objects can destroy resistive layers.

CAPACITIVE

TOUCHSCREEN

TECHNOLOGY

WORKING OF CAPACITIVE SENSORS

The sensor consists of four electrodes which are subjected to small amount of voltage.

As the human body is also an electrical conductor, touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance.

The location is then sent to the controller for processing. Unlike resistive touchscreens, you can't use a capacitive

touchscreen with gloves in winter time: you need a special capacitive stylus, or a special designed glove with finger tips that generate static electricity.

SURFACE

ACOUSTIC

WAVE

TOUCHSCREENTECHNOLOGY

WORKING OF SAW TECHNOLOGY

Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touchscreen panel.

On the pure glass substrate there are four piezoelectric transmitter and receiver transducer on three corners of both X Y axis.

The SAW controller sends 5 MHz electrical signal to X Y axis transmitting transducers.

When the touchscreen is touched the finger absorbs a portion of a wave passing across the surface, which is sensed by receiving transducer.

INFRARED

TOUCHSCREEN

TECHNOLOGY

WORKING OF INFRARED SENSORS

An infrared touchscreen uses an array of X-Y infrared LED and photodetector pairs around the edges of the screen to detect a disruption in the pattern of LED beams.

these LED beams cross each other in vertical and horizontal patterns. This helps the sensors pick up the exact location of the touch.

Unlike all other touchscreens, infrared touchscreens do not require any patterning on the glass which increases durability and optical clarity of the overall system.

COMPARISON OF TECHNOLOGIESResistive SAW Infrared Capacitan

ce

Durability 5 Years 5 Years 3 Years 2 Years

Stability High Higher High Good

Transparency

ok Good High Higher

Touch Type Anything Finger/Pen Sharp Object

Conductive

Response Time

< 10 ms < 10 ms < 20 ms < 15 ms

Application

ERGONOMICS AND USAGE•Finger Stress•The stress on human fingers when used for more than a few minutes at a time a significant pressure is requiredand the screen is non-flexible.

•Finger Prints•Touch screens also suffer from the problem of fingerprints on the display.This can be mitigated by the use of materials with optical coatings designed to reduced the visibleeffects of fingerprint oils.

•Finger nail as Stylus•Rather than pressing with the soft skin of an outstretched fingertip, the finger is curled over, so that the top of the forward edge of afingernail can be used instead

•Gorilla Arm•The defect is usually seen in Fine Art Painters due to their posture and repetitiveness of their movements while painting.

FUTURE OF TOUCHSCREEN TECHNOLOGIES

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

THANK YOU

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