touch screen technology | touch screen panel comparison

This article on touch screen technology basics mentions comparison between different touch screen panels. It mentions different methods used in touch screen technologies and selection guide to buy right touch screen panels (TSPs) for use. It also mentions advantages and disadvantages of touch screen.

Definition: Touchscreen is a human-machine interface. It gets activated by user either with a stylus or with single/multi finger touch on the panel where specific functions are displayed. Touch input can instantly provide audio/visual feedback to the user to confirm the choice made. The beauty of this touch screen technology is that user can directly interact with the device without the need of mouse or keyboard.

The touch screen contains independent X-Y coordinate system which is calibrated to display matrix. The touch point is determined by embedded computer by X-Y coordinates of the touch point.

Touchscreens are commonly found in devices which include smartphones, PCs, Laptops, TVs, game consoles, iPADs and electronic voting machines.Touch screen technology has become dominant due to wide availability of Touch sensors and firmware developers.

resistive touch screen panel

Following are the characteristics of ideal touch screen:
• It should not degrade image on the display panel.
• It should have resolution equal to video display.
• Activation should be independent of nature of styli and gloved/non gloved finger.
• It should be capable of providing feedback to user.
• It should have modular architecture.
• It requires precise control and selection of targets.
• It should withstand harse environmental conditions such as moisture, pressure, grease, dust, vibration etc.

Comparison between touch screen technologies

Following are the different types of touch screen technologies used for sensing touch.
• Resistive technology
• Capacitive technology
• Capacitive Projected technology
• Infrared grid technology
• SAW based
The selection of proper touch screen technology depends on specific applications and specifications of each. All the touch screens comprised of two parts viz. screen overlay and information processing controller. The latest touch screen technologies include optical touch screens and near field imaging touch screens.

Single touch technology is used in ATM machines while multi touch technology is used in smartphones.

Features Resistive Capacitive Projected capacitive Infrared SAW
Response time <15ms <15ms <15ms <20ms <10ms
Multi-touch Limited Not supported Supported Supported Not supported
Transmission /clarity 75 to 85% 90 to 98% 90 to 98% 95 to 100% 90 to 98%
High sensitivity or light touch Good Very good Very good Best Very good

Selection guide to buy touch screen Panel (TSP)

Following factors are considered to buy right touch screen panel (TSP) for use.
• Touch type • Screen Size • Accuracy of touch • Touch screen resolution • Response time • transmission/clarity • life expectancy • resistance to scratch, chemical, dust and grease • Ergonomics • Environment

Advantages and disadvantages of touch screen panels

Following are the advantages of touch screen technology:
• It is simple technology and user friendly.
• It does not require mouse or keyboards.
• Wide variety of touch screen options are available as per need.
• It can withstand against shock and vibration.
• It can withstand against chemical or oil vapours.
• The technology is immune against nearby electric or magnetic fields.
• It is scratch resistance and hence will have longer life.

Following are the disadvantages of touch screen panel:
• It is not easy for elders to learn this technology and often leads to wrong touches which leads to opening of unwanted functions on the device.
• Capacitive surface type touch screens do not support touch with gloves.
• Capacitive and projected capacitive do not support use of soft tip stylus.
• Touch screen technology is evolving and it will take sometime to have cost affordable devices for common man use.

Sensors and Transducers Related Links

Touch sensor    Proximity Sensor    Occupancy Sensor vs Motion Sensor    LVDT and RVDT sensor    Position, displacement and level sensor    force sensor and strain sensor    temperature sensor    pressure sensor    Humidity sensor    MEMS sensor    Haptic sensor    Wireless sensor   


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