TOUCH SCREEN TECHNOLOGY

Satendra Kumar 1st sem Mechanical Eng Presented By Satendra Kumar 1st sem Mechanical Eng

TALK FLOW INTRODUCTION HISTORY FUNCTIONS WORKING DIFFRENT TOUCH SCREEN TECHNOLOGIES APPLICATION CONCLUSION

INTRODUCTION A touch screen is a computer display screen that is sensitive to human touch, allowing a user to interact with the computer by touching pictures or words on the screen. A touch screen is an input device that allows users to operate a PC by simply touching the display screen which has a sensitive glass overlay placed on it . A touch screen accepts direct onscreen inputs.

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. The University of Kentucky Research Foundation named it as “Elograph”. The "Elograph" was not transparent like modern touch screens. In 1974, the first true touch screen incorporating a transparent surface came.

FUNCTIONS OF TOUCH SCREEN Pressure sensitive activation-by finger or stylus. Emulates mouse functions-click, double click, & drag. Touch screen & mouse can be used concurrently. Durable & scratch resistant coated surface. Compatible with Windows 95,98,NT,2000,XP,Macintosh,Linux.

HOW DOES A TOUCHSCREEN WORKS? A basic touch screen has three main components: touch sensor controller software driver

1.TOUCH SENSOR A touch screen sensor is a clear glass panel with a touch responsive surface which is placed over a 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.

2.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.

3.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 mouse-emulation type drivers. This makes touching the screen the same as clicking your mouse at the same location on the screen.

DIFFERENT TOUCH SCREEN TECHNOLOGIES RESISTIVE CAPACITIVE SURFACE WAVE INFRARED DISPERSIVE SIGNAL TECHNOLOGY

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

Contd. Pressing the flexible top sheet creates electrical contact with the coating on the glass. The touch screen controller gets the alternating voltages between the two layers and converts them into the digital X and Y coordinates of the activated area.

Advantages of Resistive Technology Can be activated with any device Low cost solution Low power consumption

Disadvantages of Resistive Technology Poorer durability compared to other technologies Very short life, especially considering cosmetic wear

CAPACITIVE TOUCH SCREEN TECHNOLOGY In the capacitive system, a layer that stores electrical charge is placed on the glass panel. When a user touches, some of the charge is transferred to the user, so the charge on the capacitive layer decreases. This decrease is measured in electrodes located at each corner of the monitor. The computer then calculates the coordinates, from the relative differences in charge at each corner.

Contd. A finger touch draws current from each corner. Then the controller measures the ratio of the current flow from the corners and calculates the touch location

Capacitive Technology ADVANTAGES   More durable than resistive Higher transmittance than resistive DISADVANTAGES     Accepts input from finger only.                             Accuracy is dependent on capacitance of person

SURFACE WAVE TECHNOLOGY It has a transmitting and receiving transducers for both the X and Y axes. The touchscreen controller sends a five-megahertz 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.

Contd. Reflectors on the opposite side gather and direct the waves to the receiving transducer, which reconverts them into an electrical signal. When you touch the screen, you absorb a portion of the wave travelling across it. The receivers can detect a drop in amplitude and thus coordinate is calculated.

ADVANTAGES     Very high transmittance    Very high durability   DISADVANTAGES   Requires “soft” input device Surface obstructions can cause a false touch

INFRARED TOUCH SCREEN TECHNOLOGY IR makes use of a “frame” around the perimeter of the display. On two sides there are closely spaced IR LEDs and on the opposing two sides there are matching photo transistors. The LEDs are turned on in sequence and the signal is read from the matching transistor. If no signal is read, then that indicates a blocked IR beam, meaning a touch.

ADVANTAGES Highest quality of underlying image Very high transmittance       Very high durability and reliability DISADVANTAGES Lower resolution than other technologies     Surface obstructions can cause a false touch

DISPERSIVE SIGNAL TECHNOLOGY This is the recent most technology, introduced in 2002. It uses sensors to detect the mechanical (vibrational)energy in the glass that occur due to a touch. Complex algorithms then interpret this information and provide the actual location of the touch.

APPLICATIONS Public Information Displays tourism displays, trade show displays Customer Self-Service stores, restaurants, transportation hubs, ATM and airline e-ticket terminals. And many more uses... computerized gaming, student registration systems, multimedia software, financial and scientific applications, and more.

CONCLUSION Touchscreens, touch panels or touchscreen panels are display overlays which have the ability to display and receive information on the same screen. Touchscreens also have assisted in recent changes in the PDAs, making these devices more usable.

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