Manish bharti B.TECH (EC)3RD YEAR

TOUCHSCREEN TECHNOLOGY

IntroductionIntroduction

A TOUCH  SCREEN IS  AN ELECTRONIC  VISUAL DISPLAY THAT  CAN  DETECT  THE  PRESENCE  AND LOCATION  OF  A  TOUCH  WITHIN  THE  DISPLAY  AREA. TOUCH  SCREENS  CAN  SENSE  FINGER  AND  OTHER PASSIVE OBJECTS, SUCH AS A STYLUS. HOWEVER, IF THE OBJECT SENSED IS ACTIVE, AS WITH A LIGHT PEN.

History & DevelopmentHistory & DevelopmentIn 1971 Dr. Sam Hurst, founder of Elographics developed the first touch opaque sensor “Elograph” at the University of Kentucky. 

In 1974 He developed the first real touch screen. 

In 1977, Elographics developed the five-wire resistive technology then with the backing of Siemens Corporation, developed a curved glass sensor called the touch screen. 

The new transparent technology, AccuTouch, was later developed by the founders of Elographics, Dr. Hurst and Bill Colwell

Dr. Samuel HurstDr. Samuel Hurst           The  father  of  the  touch  screen  technology is Dr.  Samuel  Hurst.  In  1971,  while  he  was working  as  an  instructor  at  the  University  of Kentucky Research Foundation, he had to read a  great  volume  of  information  during  the graduation  exams.  In  an  effort  to  save  some time he  invented  the  first  touch  sensor  that he called  “Еlo  graph”(electronic  graphics), which allowed him to enter data faster. 

First Touch PhoneFirst Touch Phone       Apple was the first with a touch screen  phone  in 1983.  Jason  Ford of Elo  Touch  Systems,  the company  whose  founder  invented touch  screen  technology,  for providing the touch technology. In 1971,  the  first  "touch  sensor" was developed by Doctor Sam Hurst.

First Touch MobileFirst Touch Mobile The Nokia 7710 is a first touch screen mobile phone model produced by Nokia. The 7710 is based on the Nokia 7700 which was never released. It is Nokia's first, and so far only smart phone to run the Series 90 GUI a top the Symbian OS.

Types of Touch TechnologiesTypes of Touch TechnologiesThere are mainly 4 types of touch Technologies:-There are mainly 4 types of touch Technologies:-

1.Resistive1.Resistive

2. Surface acoustic wave2. Surface acoustic wave

3. Capacitive3. Capacitive

4. Infrared4. Infrared

ResistiveResistive

A resistive touch screen panel is composed of several layers, the most important of which are two thin, metallic, electrically conductive layers separated by a narrow gap.

When an object, such as a finger, presses down on a point on the panel's outer surface the two metallic layers become connected at that point.

This causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing. It is used in Grocery Stores, Hotels, Restaurants and Retail Stores.

Advantages & Disadvantages of ResistiveAdvantages & Disadvantages of Resistive AdvantagesAdvantages◦Cost-effective solution◦Activated by any stylus◦Very accurate◦Low power requirements◦Liquids won't affect touch screen performance

DisadvantagesDisadvantages◦Polyester surface can be damaged◦Lower endurance (35 million touches)

Surface Acoustic Wave (SAW)Surface Acoustic Wave (SAW) Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touch screen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. SAW touch screen technology is suggested for use in ATMs, Amusement Parks, Gaming Environments, Industrial Control Rooms etc.

Advantages & Disadvantages of Advantages & Disadvantages of SAWSAW

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◦Doesn't support drag or draw effectively

CapacitiveCapacitive A capacitive touch screen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO).

As the human body is also a conductor, touching the surface of the screen results in a distortion of the body's electrostatic field, measurable as a change in capacitance.

Advantages & Disadvantages of Advantages & Disadvantages of CapacitiveCapacitive

Advantages◦Scratch resistant, durable surface◦High endurance (225 million touches)◦Very accurate◦Good optical clarity◦Liquids won't affect touch screen performance

Disadvantages◦Does not work with gloved fingers or stylus

InfraredInfrared

An infrared touch screen uses an array of X-Y infrared LED and photo detector pairs around the edges of thee screen to detect a disruption in thee pattern of LED beams.

Infra-red bezels have proven to be a very reliable technology for use in ATMs,Medical Instrumentation and Transportation Tracking applications.

Advantages & Disadvantages of Infrared Advantages & Disadvantages of Infrared Touch ScreenTouch Screen

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 ChartTouch Screen Technology Comparison ChartResistive Infrared SAW Capacitive

Touch Resolution

High High Average High

Clarity Average Good Good Good

Operation Finger or Stylus Finger or Stylus Finger or Soft-tipped Stylus

Finger only

Durability Can be Damaged by Sharp Objects

Highly Durable Susceptible to Dirt and Moisture

Highly durable

Advantages & Disadvantages of all Touch TechnologyTouch screens have several advantages over other pointing devices:

A touch screen is easy to use (as the user simply touches what he or she sees on the display).

Save space as no buttons are required.

Touching a visual display of choices requires little thinking and is a form 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.

DISADVANTAGESScreen has to be really big not to miss things when pressing them with your finger:

Big screen leads to low battery life.

Touch screen means screen can’t be read too well in direct sunlight as it applies an additional not 100% transparent.

Touch screen devices usually has no additional keys (see the iPhone) and this means when an app crashes, without crashing the OS, you can’t get to the main menu as the whole screen becomes unresponsive.

Most user interfaces are not optimized for thumb operation, so a stylus in necessary, and this means using two hands

Screens get very dirty.

These devices require massive computing power which leads to slow devices.

CONCLUSIONCONCLUSION Though the touch screen technology contains some limitations it’s very user friendly, fast, accurate, easy for the novices & fun to operate. It has been widely accepted. And now by just modifying a little it can replace the mouse and key board completely in near future.