TOUCH SCREEN TECHNOLOGY
Nov 15, 2014
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.