Touch screen controllers are circuits that interface between a touch screen sensor and the device the sensor is used to control. They plug into touch screen sensors and interface with computers via serial connections such as RS232 and the universal serial bus (USB). Touch screen sensors have a transparent surface that is surrounded by a sensor array that provides position information to a processor. They enable operators to use a touch screen display as the input device, thus replacing the keyboard or mouse as the primary method of interacting with the device. Examples of touch screen technology include automatic teller machines (ATMs) and point-of-sale (POS) kiosks. Both types of products may use multi-point sensing or universal touch screen controllers. Touch screen controllers are used with several one or more types of touch screen sensors. Examples include capacitive touch screen sensors and resistive touch screen sensors. Complete touch screen systems are also available.
Capacitive touch screen sensors are placed on a special panel coated with indium tin oxide. The panel conducts a continuous electrical current across the sensor in order to detect changes in capacitance. Resistive touch screen panels are also coated with a thin-film, but are designed to produce an electrically-resistive layer. Changes in electrical resistance are marked as touch events and sent to touch screen controllers for processing. Complete touch screen systems allow users to operate a device by touching the display screen. These products consist of a touch screen sensor array, a touch screen controller card, and a software driver.
Both capacitive touch screen controllers and resistive touch controllers carry numerous hardware and software specifications. Hardware parameters include power requirements, operating temperature, storage temperature, relative humidity, communication protocol, resolution, accuracy tolerance, report rate, response time, and regulatory approvals such as CE Marking and FCC-B compliance. Software parameters for touch screen controllers include calibration, compensation, draw test results, controller setting, language support, mouse emulation, sound notification, double-click speed and double-click area, operating system (OS) support, communications (COM) port support, and display support. Touch screen controllers that can also function as a display controller carry additional product specifications and provide additional features.