TOUCH SCREEN TECHNOLOGY

DEFINITION What is touch screen

INTRODUCTION

Works with the principle of CRT (Cathode Ray Tube) technology.

Input device --> Operates a PC by simply touching the display screen.

Made of sensitive glass overlay & desired inputs can be given by touching it.

Inputs --> External (light pen) or an internal device (touch overlay and controller) .

COMPONENTS OF TOUCH SCREEN

Three major components viz,

Touch sensor

Controller

Software driver

TOUCH SENSORS

Touch sensor

Covering screen

CONTD..

Touch sensor --> In between clear glass panels.

Responsive area --> Entire viewable area of the display screen.

Sensors --> Detects electrical current or signal.

Touching -->causes a voltage or signal change, thereby the location can be determined.

CONTROLLER

CONTD…

PC card --> Touch sensor and the PC.

Change in voltage --> Translated into the information that CPU understands.

Translated bits --> Position where the touch occurs.

Processor --> change the screen accordingly.

SOFTWARE DRIVER

Acts as a bridge --> Screen and processor.

Makes the operating system --> To interpret the touch event information.

Touch screen drivers today --> Mouse-emulation type driver ( like touching the screen the same as clicking mouse)

Recent research --> To make it as PNP

TYPES OF TOUCH SCREEN

Resistive Touch screen

Surface wave Touch screen

Capacitive Touch screen Surface capacitive Projected capacitive

Infrared Touch screen

RESISTIVE TOUCH SCREENS

RESISTIVE TOUCH SCREEN

CONTD… 1. Polyester Film.

2. Top Resistive Layer.

3. Conductive Transparent Metal Coating.

4. Bottom Resistive Layer .

5. Insulating Dots .

6. Glass Substrate

WORKING OF RESISTIVE SENSORS

Resistive touch screen monitor composed of : Flexible top layer Rigid bottom layer Insulating dots Along with touch screen controller.

Top & Bottom layers --> transparent metal oxide coating.

Pressure over the flexible top sheet --> Makes electrical contact between the resistive layers & the switch closing in the circuit.

Controller --> Alternating voltages & converts them into the digital X and Y coordinates.

CONTROLLER NAME:

VS20UA CONTROLLER

Supply Voltage 5.0V  DC

Maximum Current  20mA

Resolution 12-bit

PROPERTIES

2 conductive layers that connects when touched.

Capable of multi touch.

Not affected by dirt or dust.

Good for outdoor use.

SURFACE WAVE TOUCH SCREEN

Introduction

SURFACE WAVE TOUCH SCREEN

WORKING OF SURFACE WAVE SENSORS

Contains Transmitting and receiving transducers

Touch screen controller --> 5 MHz electrical signal to the transmitting transducer.

Converts electrical signal --> ultrasonic waves within the glass.

Waves --> Directed across the front surface of screen.

Reflectors - -> Reflects & directs towards receiving transducer.

Receiving transducer --> reconverts --> An electrical signal & digitally maps the touch screen

CONTROLLER NAME:

2701RSU CONTROLLER

Voltage +5 VDC

Baud Rate 9600

Touch Resolution 12bit, size independent

Conversion Time 10 ms per coordinate set

CAPACITIVE TOUCHSCREEN

Introduction

CAPACITIVE TOUCHSCREEN Figure

WORKING OF CAPACITIVE TOUCHSCREEN

Uniform conductive coating on a glass panel.

Operation --> Electrodes around the panel's edge evenly distribute a low voltage across the conductive layer & creates an uniform electric field.

Finger touch --> Draws current from each corner.

Controller --> Measures ratio of the current flow from the corners & calculates the touch location.

Capacitance --> Finger and the sensor grid.

LAYERS OF CAPACITIVE TOUCHSCREEN

Contains 3layers ,viz

Front Protective glass

Back protective glass

- provides optical & strength enhancement options

Middle layer laminated sensor grid micro-fine wires

CONTROLLER Name:

5000 RSU SERIAL CONTROLLER

Supply Voltage: +5 V DC or +12V

Baud Rate 9600 (default) and

19200 Touch Resolution

12bit, size independent. Conversion Time

Approximately 15 ms per coordinate set

PROPERTIES

Conductive coating that emits electric field.

Very durable.

Must be touched by some conductive materials.

Capable of multi touch.

PROS & CONS OF TOUCH SCREENS

Direct pointing to the objects.

Fast.

Finger or pen is usable (No cable required)

No keyboard necessary

Suited to all interactive applications.

Low precision when we use finger.

Screen may be covered more by using hand

No direct activation to the selected function

PROS CONS

APPLICATIONS Public Information Displays:::

Tourism displays Trade show display Awareness kiosks

Customer Self-Services::: General departmental Stores Restaurants ATMs Airline ticket terminals, etc.

Other uses::: Digital jukeboxes Computerized gaming Student Registration systems, etc.

EXCLUSIVE HIGH PERFORMANCE OF TOUCH SCREEN TECHNOLOGY

High resolution enhanced infrared

BENEFITS1:Easier to pin point

2:Better drag and drop

3:Extra resolution

4:Better sensitivity to environment

RECENT PRODUCT S UNDER DEVELOPEMENT

RECENT TRENDS Introduction of

i-PAN7: Flat Touchscreen computer - Panel PC

Introduced by Keith & Koep of Japan.

Small frame computer.

Runs with Windows Embedded CE & built with low power ARM processor.

Uses Capacitive touch panels.

DISADVANTAGES User hand’s may obscure the screen Screens need to be installed at lower position

and tilted to reduce arm fatigue Some reduction in image brightness may occur They cost more than alternative devices

HOW IS TOUCH SCREEN DIFFERENT FROM OTHER DEVICES

No special commands to learn

No use of keyboards

Entering wrong information is impossible

No fear of damage or lost of loose hardware pieces

CONCLUSION Though the Touch screen technology contains

some limitations it’s user friendly. Fast. Accurate. easy to operate.

It has been widely accepted and a little modification can replace the mouse and key board completely in near future.