seminar on touch screen technology

Touch Screen Technology: 

Touch Screen Technology Submitted BY :- Saransh Agarwal Branch :- Comp. Science & Engg. B.Tech 3 rd Year (6 th sem) Roll No. :- 0815310079

History: 

History 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. In 1977, Elographics developed and patented five-wire resistive technology, the most popular touch screen technology in use today.

How Does a Touchscreen Work?  : 

How Does a Touchscreen Work? A basic touchscreen has three main components: 1 Touch sensor; 2 Controller; 3 Software driver. The touchscreen is an input device, so it needs to be combined with a display and other device to make a complete touch input system.

Touch Sensor: 

Touch Sensor A touch screen sensor is a clear glass panel with a touch responsive surface. The touch sensor is placed over a display screen so that the responsive area of the panel covers the viewable area of the video screen. The sensor generally has an electrical current or signal going through it and touching the screen can cause a voltage or signal change. This change is used to determine the location of the touch to the screen.

Controller: 

Controller The controller 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 controller determines what type of interface/connection you will need on the PC. Specialized controllers are also available that work with DVD players and other devices.

Software Driver: 

Software Driver The driver allows the touchscreen and computer to work together. It tells the computer's 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 as same as clicking your mouse at the same location on the screen.

Touchscreen Technology : 

Touchscreen Technology Resistive touchscreen Capacitive touchscreen Infrared touchscreen Surface acoustic wave (SAW) touchscreen Strain gauge touchscreen Optical imaging touchscreen Dispersive signal technology touchscreen

Resistive touchscreen: 

Resistive touchscreen Structure Resistive touch screens consist of a glass or acrylic panel that is coated with electrically conductive and resistive layers made with indium tin oxide (ITO) .The thin layers are separated by invisible spacers.

Resistive touchscreen: 

Resistive touchscreen Characters: Cost effective solutions Activated by a stylus, a finger or gloved hand Not affected by dirt, dust, water, or light 75%~85% clarify resistive layers can be damaged by a very sharp object

Projected-capacitive touchscreen: 

Projected-capacitive touchscreen Structure Projected capacitive touchscreens have front and back protective glass providing optical and strength enhancement options. Its middle layer consists of a laminated sensor grid of micro-fine wires, and optical enhancement options.

Projected-capacitive touchscreen: 

Projected-capacitive touchscreen During a touch, capacitance forms between the finger and the sensor grid.The embedded serial controller in the touchscreen calculates touch location coordinates and transmits them to the computer for processing.

Surface-capacitive touchscreen: 

Surface-capacitive touchscreen Structure Surface capacitive technology consists of a uniform conductive coating on a glass panel. Electrodes around the panel’s edge evenly distribute a low voltage across the conductive layer, creating a uniform electric field.

Surface-capacitive touchscreen: 

Surface-capacitive touchscreen Working principle A human body is an electric conductor, so when you touch the screen with a finger, a slight amount of current is drawn, creating a voltage drop. The current respectively drifts to the electrodes on the four corners. Theoretically, the amount of current that drifts through the four electrodes should be proportional to the distance from the touch point to the four corners.

Capacitive touchscreen: 

Capacitive touchscreen Characters: Durable and resistant to scratches for demanding applications Faster and more responsive Immune to surface contaminants Superior optical clarity, brighter display and less surface reflection Must be touched by finger, will not work with any non-conductive input

Infrared touchscreen: 

Infrared touchscreen Infrared (IR) technology relies on the interruption of an IR light grid in front of the display screen. The touch frame contains a row of IR-light emitting diode (LEDs) and photo transistors, each mounted on two opposite sides to create a grid of invisible infrared light. The IR controller sequentially pulses the LEDs to create a grid of IR light beams. When a stylus, such as a finger, enters the grid, it obstructs the beams. One or more photo transistors from each axis detect the absence of light and transmit signals that identifies the x and y coordinates.

Infrared touchscreen: 

Infrared touchscreen

Infrared touchscreen: 

Infrared touchscreen Characters: Clear as glass, improves reading ability Most durable surface

Multi-touch technology: 

Multi-touch technology Multi-touch denotes a set of interaction techniques which allow computer users to control graphical applications with several fingers. Products: Apple iPhone, iPod touch, MacBook Air, and MacBook Pro Microsoft Surface ……

Reference : 

Reference http://en.wikipedia.org/wiki/Touchscreen Research Note on Touch Screen Sensors by Andrew Nathanson http://www.wisegeek.com/what-are-touch-screen-monitors.htm

Thanks for Your Cooperation Friends…… : 

Thanks for Your Cooperation Friends……  Have a good day guys……….