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Friday, July 26, 2013

PPT On Touchscreen

Presentation On Touchscreen

Touchscreen Presentation Transcript: 

2.What is a Touchscreen?
A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area.
The term generally refers to touching the display of the device with a finger or hand. Touchscreens can also sense other passive objects, such as a stylus.
 Touchscreens are common in devices such as game consoles, all-in-one computers, tablet computers, and smartphones.

3.How Does a Touchscreen Work?
A basic touchscreen has three main components:
Touch sensor;
Software driver.

      The touchscreen is an input device, so it needs to be combined with a display and a PC or other device to make a complete touch input system.

4.Touch Sensor
A touch screen sensor is a clear glass panel with a touch responsive surface. The touch sensor/panel is placed over a display screen so that the responsive area of the panel covers the viewable area of the video screen. There are several different touch sensor technologies on the market today, each using a different method to detect touch input. 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.

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. Controllers are available that can connect to a Serial/COM port (PC) or to a USB port. Specialized controllers are also available that work with DVD players and other devices.

6.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. This allows the touchscreen to work with existing software and allows new applications to be developed without the need for touchscreen specific programming.

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

8.Resistive Touchscreen
A resistive touchscreen panel comprises several layers, the most important of which are two thin, transparent electrically-resistive layers (made with ITO) separated by a thin space. These layers face each other, with a thin gap between. The top screen (the screen that is touched) has a coating on the underside surface of the screen. Just beneath it is a similar resistive layer on top of its substrate. One layer has conductive connections along its sides, the other along top and bottom.

9.Resistive Touchscreen
Working: A voltage is applied to one layer, and sensed by the other. When an object, such as a fingertip or stylus tip, presses down on the outer surface, the two layers touch to become connected at that point: The panel then behaves as a pair of voltage dividers, one axis at a time. By rapidly switching between each layer, the position of a pressure on the screen can be read. 

10.Resistive Touchscreen
Advantages: High resistance to liquids and contaminants, Low cost.
Disadvantages: Risk of damage by sharp objects, poorer contrast due to having additional reflections from the extra layer of material placed over the screen. 

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