Touch screen sensors are composed of a transparent touch screen surface surrounded by a sensor array that provides positional information to a processor. A touch screen sensor enables the display to be used as an input device and replaces the keyboard or mouse as the primary method of input for interacting with a display's content. Touch screen sensors can be attached to computers and handheld devices. Touch screen technology is used by banks in the form of automatic teller machines (ATMs).

Types of Touch Screen Sensors

There are several basic types of touch screen sensors. Examples include:

• capacitive glass touch screen sensors
• resistive touch screens
• complete touch screen systems

A capacitive glass touch screen sensor is placed on a touch screen panel that is coated with indium tin oxide. The panel conducts a continuous electrical current across the sensor in order to detect changes in capacitance. A resistive touch screen panel is also coated with a thin-film, but in order to produce an electrically resistive layer. Each change in electrical resistance is marked as a touch event and sent to a controller for processing. A complete touch screen system allows a user to operate a computer or terminal by touching the display screen. A touch screen system consists of a touch screen sensor array, a controller card, and a software driver.

Specifications

Selecting touch screen sensors requires an analysis of performance specifications and application requirements. In general, resistive touch screens provide only 75 percent clarity. They are available in 12.1 in., 15.0 in., 17.1 in., 18.1 in., 19.1 in., and 20.1 in. models. Four-wire, five-wire, and eight-wire resistive touch screens are commonly available. Depending on a product’s specifications, touch screen technology may be used in touch screen thermostats for climate control. A touch screen thermostat is programmable and offers precise temperature control. Touch screen thermostats may also include backlighting or other special features. Like other touch screen sensors, these products are designed and manufactured to meet a variety of requirements.

Applications

Touch screen sensors are used in many applications. Some products are used in pen digitizers for signature capture, smart phones, or personal digital assistants (PDAs). Other products are used in ATMs or portable game consoles. Specialized touch screen sensors can also be used in information appliances. Capacitive glass touch screen sensors can detect contact from an operator who is wearing gloves or other protective gear.

Related Information

IEEE Spectrum—Beyond Touch: Tomorrow's Devices Will Use MEMS Ultrasound to Hear Your Gestures

IEEE Spectrum—Stretchable Touch Pad Could Become Wearable Touch Screen