Touchscreen

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NAME - Abhishek Ranjan R.NO. – RE3004 B58 REG.NO.-11001020 1 Touch screen Technology

WHAT IS TO BE EXPLAINED..:

WHAT IS TO BE EXPLAINED.. INTRODUCTION TO THE TECHNOLOGY HISTORY HOW IT WORKS ? TOUCH SCREEN DIVERSITY CONTROLERS USED MANUFACTURES OF TOUCH SCREEN 2

INTRODUCING THE TECHNOLOGY :

3 INTRODUCING THE TECHNOLOGY A touch screen is an input device that allows users to operate a PC by simply touching the display screen. The display screen has a sensitive glass overlay placed on it and we could give the desired input by touching it. A touch screen is based on CRT (Cathode Ray Tube) technology, that accepts direct onscreen input. The ability for direct onscreen input is facilitated by an external (light pen) or an internal device (touch overlay and controller) .

HISTORY:

HISTORY Touch screens emerged from academic and corporate research labs in the second half of the 1960s. One of the first places where they gained some visibility was in the terminal of a computer-assisted learning terminal that came out in 1972 as part of the PLATO project. The HP-150 from 1983 was probably the world's earliest commercial touch screen computer. It doesn't actually have a touch screen 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. 4

HOW DOES A TOUCHSCREEN WORK?:

5 HOW DOES A TOUCHSCREEN WORK? Main touch screen components: Touch sensor Controller Software driver

TOUCH SENSOR:

6 TOUCH SENSOR A touch screen sensor is a clear glass panel with a touch responsive surface which is placed over a display screen so that the responsive area of the panel covers the viewable area of the 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

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CONTROLLER:

8 CONTROLLER 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.

SOFTWARE DRIVER:

9 SOFTWARE DRIVER 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 a mouse-emulation type driver. This makes touching the screen the same as clicking your mouse at the same location on the screen.

TOUCH SCREEN DIVERSITY:

10 TOUCH SCREEN DIVERSITY Resistive Touch screen Surface wave Touch screen Capacitive Touch screen *Surface capacitive *Projected capacitive Near Field Imaging Touch screen Infrared Touch screen

RESISTIVE TOUCH SCREEN:

11 RESISTIVE TOUCH SCREEN Polyester Film . Top Resistive Layer. Conductive Transparent Metal Coating. Bottom Resistive Layer . Insulating Dots . Glass Substrate

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12 Glass Substrate Insulating Dots Bottom Resistive Layer Conductive Metal Coating Polyester Film Top Resistive Layer

Continued…:

13 Continued… Resistive touch screen monitor is composed of a flexible top layer and a rigid bottom layer separated by insulating dots, attached to a touch screen controller. The inside surface of each of the two layers is coated with a transparent metal oxide coating Pressing the flexible top sheet creates electrical contact between the resistive layers, producing a switch closing in the circuit. The controller gets the alternating voltages between the two layers and converts them into the digital X and Y coordinates of the activated area.

VS20UA CONTROLLER:

14 VS20UA CONTROLLER Supply Voltage 5.0V  DC Maximum Current 20mA (Pick) Resolution 12-bit

SURFACE WAVE TECHNOLOGY:

15 SURFACE WAVE TECHNOLOGY It has a transmitting and receiving transducers for both the X and Y axes. The touchscreen controller sends a 5 MHz 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—a digital map of the touchscreen

Continued…:

16 Continued… When you touch the screen, you absorb a portion of the wave traveling across it. The received signal is then compared to the stored digital map, the change recognized, and a coordinate calculated. . The digitized coordinates are transmitted to the computer for processing.

2701RSU CONTROLLER:

17 2701RSU CONTROLLER Voltaze +5 VDC Baud Rate 9600 (default) and 19200 Touch Resolution 12bit, size independent Conversion Time 10 ms per coordinate set

CAPACITIVE TOUCH SCREENS Surface Capacitive:

18 CAPACITIVE TOUCH SCREENS Surface Capacitive Electrodes around the panel's edge distribute a low voltage across the conductive layer & creates an uniform electric field. An uniform conductive coating on a glass panel. A finger touch draws current from each corner. Controller measures the ratio of the current flow from the corners.

5000 RSU SERIAL CONTROLLER:

19 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

Projected Capacitive Touch screen:

20 Projected Capacitive Touch screen 3layers:-front and back protective glass provides optical and strength enhancement options & middle layer consists of a laminated sensor grid of micro-fine wires

Continued…:

21 Continued… During a touch, capacitance forms between the finger and the sensor grid. The embedded serial controller in the touch screen calculates touch location coordinates and transmits them to the computer for processing.

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Manufactures of Touch screen :

Manufactures of Touch screen Crestron electronics 3M Hitachi I light Dynalite Touch international Next window

Pros & Cons:

24 Pros & Cons Direct pointing to the objects. Fast Finger or pen is usable (No cable required) No keyboard necessary Suited to: novices, application for information retrieval etc Low precision by using finger User has to sit or stand closer to the screen The screen may be covered more by using hand No direct activation to the selected function

CLOSING THOUGHTS:

25 CLOSING THOUGHTS Though the touch screen technology contains some limitations it’s very user friendly, fast, accurate, easy and fun to operate. It has been widely accepted. And now by just modifying a little it can replace the mouse and key board completely in near future.

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26 THANK YOU

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