INTRODUCTIONA touchscreen is a display that can detect the presence and location of a touch within the display area.The term generally refers to touch or contact to the display of the device by
The touchscreen has two main attributes:1. It enables one to interact with what is displayed directly on the screen, where it is displayed, rather than indirectly with a mouse or touchpad.2. It lets one do so without requiring any intermediate device, again, such as a stylus that needs to be held in the hand. Such displays can be attached to computers or, as terminals, to networks.
History The first touch screen was a capacitive touch screen developed by E.A. Johnson at the Royal Radar Establishment, Malvern, UK. The inventor briefly described his work in a short article published in 1965 and then more fully - along with photographs and diagrams - in an article published in 1967. 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 worlds earliest commercial touchscreen computer.
Development • The development of multipoint touchscreen facilitated the tracking of more than one finger on the screen, thus operations that require more than one finger are possible. • These devices also allow multiple users to interact with the touchscreen simultaneously. • With the influence of the multi-touch- enabled iPhone and the Nintendo DS, the touchscreen market for mobile devices produced 5 billion in 2009.
TOUCH SENSOR .A touch sensor is a clear glass panel with a touch responsive surface .The sensor generally has an electrical signal going through it andtouching the screen causing a signal change.The signal change is used to determine the location of the touch to thescreen.
CONTROLLER The controller is small PC card that connects between the touch sensor and PC. It takes information from the touch sensor and translate in to information that PC can understand.
SOFTWARE DRIVERThe driver is a software that allows thetouch screen and computer to worktogether.It tells the operating system how tointerpret the touch event information thatsent from the controller.Most of the touch screen drivers todayare mouse emulation type driver .
Construction There are several principal ways to build a touchscreen:• In the most popular techniques, the capacitive or resistive approach, manufactures coat the screen with a thin, transparent metallic layer.• When a user touches the surface, the system records the change in the electrical current that flows through the display.• Dispersive-signal technology which 3M created in 2002, measures the piezoelectric effect — the voltage generated
Technologies The types of technologies that can be found are as follows:Resistive:● The resistive touch screen uses a glass panel with a uniform conductive ITO(Indium Tin Oxide) coating on the side surface.● A PET film is a tightly suspended over the ITO coating surface of a glass panel.
Working Principle:● When the screen is touched, it pushes the conductive ITOcoating on the PET film. That results the electrical contact,producing the voltages. It presents the position touched.● Resistive touchscreen deliver cost-effective, consistent anddurable performance
• On the pure glass substrate,Surface Acoustic Wave: there are four piezoelectric transmitting and receiving transducers on the three corners for both the X and Y axes. • The SAW controller sends a 5 MHz electrical signal to the X- axis and Y-axis transmitting transducers.• When the touchscreen is touched, the finger absorbs a portion of the wave passing across the surface of the panel.• SAW can be used in any and all applications for the best possible image clarity an unlimited life.
Capacitive:• Capacitive touchscreen is a four multi-layer glass.• Small amount of voltage is applied to the electrodes on the four corners• A human body is an electric conductor, so when touched 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.• The capacitive system has very long life (about 225
Infrare d:● Conventional optical-touch systemsuse an array of infrared (IR) light-emitting diodes (LEDs) on twoadjacent bezel edges of a display, withphotosensors placed on the twoopposite bezel edges to analyze thesystem and determine a touch event.• IR eliminates the use of glass or plastic overlay that most other touch technologies require in front of the display.• High cost of the technology.• IR increases the noise floor at the optical sensor
Technology Capacitive SAW Infrared ResistiveTransparence Very good Very good Very good 75%~85% >92% >92% >92%Resolution Good Good Limited due to good spacing of IR sensorsSurface Resistant to Adversely Potential for Unaffected byContaminants moisture and affected by False activation Surface/durability other surface moisture or or dead zones contaminants. contaminants Surface From Surface Polyester top contaminants Contaminants sheet is easily scratchedSensor substrate Glass with ITO Glass with ITO Any substrate Polyester top coating coating sheet, glass substrate with ITO coatingDisplay size 8.4"-21" 10.4"-30" 10.4"-60" up to 19"Touch method Human touch finger, gloved Can use any Can use any pointing device pointing device hand or soft tip
Advantages &Disadvantages: Advantages:• User friendly.• Fast response.• Error free input.• Easy to install.• Use finger, fingernail, gloved hand, stylus or any soft-tip pointer to operate.• Easy to clean and maintain.• Compatible with Windows, Macintosh and Linux.• Does not interfere mouse and keyboard function.• Make computing easy, powerful and fun.
Disadvantages:1)Finger stress: Stress on human fingers when used for more than a few minutes at a time. (for example, ATMs).2)Fingerprints: Touchscreens can suffer from the problem of fingerprints on the display.3)User has to sit closer to the screen as compared to external keyboard.4) The screen may be covered more by using hand.
ApplicationsPublic Access:• Mobile Phones• Library resource guides• Computers• Public Transportation Schedule / Status• Airport terminal passenger internet and email systems• Automated travel and entertainment ticket dispensers
Business• Gas stations• Point of sales• Restaurants• Grocery stores• Hospital and hotel directories (check-in, registration)• Banks and Financial Reporting• Bank cash advance and teller machines
Conclusion:• Designers are trying to use touchscreen to simplify input commands for largely unsophisticated computer users.• Today, a larger share of population is PC literate, yet the touchscreen has become adopted by computer users of all abilities because it is simple, fast, and innovative.• In future there is no usage of mouse and keyboards as they will be replaced by touchscreens.