IntroductionA touch screen is an electronic visualdisplay that can detect the presenceand location of a touch within thedisplay area. Touch screens can senseFinger and other passive objects, suchas a stylus. However, if the objectsensed is active, as with a light pen.
History & Development• In 1971 Dr. Sam Hurst, founder of Elographics developed thefirst touch opaque sensor “Elograph” at the University ofKentucky.• In 1974 He developed the first real touch screen.• In 1977, Elographics developed the five-wire resistivetechnology then with the backing of Siemens Corporation,developed a curved glass sensor called the touch screen.
Dr. Samuel HurstThe father of the touch screen technologyis Dr. Samuel Hurst. In 1971, while he wasworking as an instructor at the University ofKentucky Research Foundation, he had toread a great volume of information duringthe graduation exams. In an effort to savesome time he invented the first touch sensorthat he called “Еlo graph”(electronicgraphics), which allowed him to enter datafaster.
First Touch PhoneApple was the first with a touchscreen phone in 1983. JasonFord of Elo Touch Systems, thecompany whose founderinvented touch screentechnology, for providing thetouch technology. In 1971, thefirst "touch sensor" wasdeveloped by Doctor SamHurst.
First Touch MobileThe Nokia 7710 is a first touchscreen mobile phone modelproduced by Nokia. The 7710 isbased on the Nokia 7700 whichwas never released. It is Nokiasfirst, and so far only smart phoneto run the Series 90 GUI a topthe Symbian OS.
Types of Touch TechnologiesThere are mainly 4 types of touch Technologies:-1.Resistive2. Surface acoustic wave3. Capacitive4. Infrared
ResistiveA resistive touch screen panel is composedof several layers, the most important ofwhich are two thin, metallic, electricallyconductive layers separated by a narrowgap. When an object, such as a finger,presses down on a point on the panels outersurface the two metallic layers becomeconnected at that point. This causes achange in the electrical current, which isregistered as a touch event and sent tothe controller for processing. It is usedin Grocery Stores, Hotels, Restaurants andRetail Stores.
Advantages & Disadvantages of Resistive• Advantages– Cost-effective solution– Activated by any stylus– Very accurate– Low power requirements– Liquids wont affect touch screen performance• Disadvantages– Polyester surface can be damaged– Lower endurance (35 million touches)
Surface Acoustic Wave (SAW)Surface acoustic wave (SAW) technologyuses ultrasonic waves that pass over the touch screen panel.When the panel is touched, a portion of the wave isabsorbed. This change in the ultrasonic waves registers theposition of the touch event and sends this information tothe controller for processing. SAW touch screen technologyis suggested for use in ATMs, Amusement Parks, GamingEnvironments, Industrial Control Rooms etc.
Advantages & Disadvantages of SAW• Advantages– Durable glass construction– High optical clarity– Activated by a finger, gloved hand, or soft tip stylus• Disadvantages– Moving liquids or condensation can cause false touches– Solid contaminants create non-touch areas until removed– Doesnt support drag or draw effectively
CapacitiveA capacitive touch screen panelconsists of an insulator suchas glass, coated with atransparent conductor suchas indium tin oxide (ITO). As thehuman body is also a conductor,touching the surface of the screenresults in a distortion of thebodys electrostatic field,measurable as a changein capacitance.
Advantages & Disadvantages of Capacitive• Advantages– Scratch resistant, durable surface– High endurance (225 million touches)– Very accurate– Good optical clarity– Liquids wont affect touch screen performance• Disadvantages– Does not work with gloved fingers or stylus
InfraredAn infrared touch screen usesan array of X-Yinfrared LED and photodetector pairs around the edgesof the screen to detect adisruption in the pattern of LEDbeams. Infra-red bezels haveproven to be a very reliabletechnology for use inATMs,Medical Instrumentationand Transportation Trackingapplications.
Advantages & Disadvantages of Infrared TouchScreen• Advantages-Highest quality of underlying image-Very high transmittance-Excellent anti-glare, with use of chemically etched glass-Can be activated with almost any device-Higher accuracy than other technologies-Very high durability and reliability• Disadvantages- Surface obstructions can cause a false touch– It is very sensitive and can be activated by stray touches.– Low resolution– Parallax problems
Touch Screen Technology Comparison ChartResistive Infrared SAW CapacitiveTouchResolutionHigh High Average HighClarity Average Good Good GoodOperation Finger or Stylus Finger or Stylus Finger or Soft-tipped StylusFinger onlyDurability Can beDamaged bySharp ObjectsHighly Durable Susceptible toDirt andMoistureHighly durable
Advantages & Disadvantages of all TouchTechnologyTouch screens have several advantages over other pointing devices:• A touch screen is easy to use (as the user simply touches what he orshe sees on the display).• Save space as no buttons are required.• Touching a visual display of choices requires little thinking and is aform of direct manipulation that is easy to learn.• Touch screens are the fastest pointing devices.• Touch screens have easier hand eye coordination than buttons.• Touch screens are durable in public access and in high volume usage.
Disadvantages• Screen has to be really big not to miss things when pressing them withyour finger:• Big screen leads to low battery life.• Touch screen means screen can’t be read too well in direct sunlightas it applies an additional not 100% transparent.• Screens get very dirty.• These devices require massive computing power which leads to slowdevices.
CLOSING THOUGHTSThough the touch screentechnology contains somelimitations it’s very userfriendly, fast, accurate, easyfor the novices & fun tooperate. It has been widelyaccepted. And now by justmodifying a little it canreplace the mouse and keyboard completely in nearfuture.