Touchpanel

A touchpanel is a user interface device that enables input by touching a surface. It typically consists of a touch-sensitive layer integrated with or placed over a display, allowing users to interact with software and hardware through direct contact rather than via a separate pointing device.

Common types include resistive, capacitive, infrared, and surface acoustic wave sensors. Resistive panels register pressure and a contact point, capacitive panels sense changes in electrical charge on a transparent conductor, infrared systems detect interruptions of light beams, and SAW panels use ultrasonic waves. Each type has different requirements for materials, durability, and sensing methods.

Projective capacitive and mutual capacitive designs enable multi-touch input, which supports gestures such as pinching and swiping. Touch panels may rely on a dedicated controller or digital signal processor, and communicate with host devices through protocols such as USB, I2C, or SPI. Calibration may be required to maintain accuracy, particularly in harsh environments or across temperature changes.

Common applications include smartphones, tablets, kiosks, point-of-sale terminals, industrial control panels, and automotive dashboards. Advantages include direct interaction, fast response, and potential for high durability; disadvantages can include sensitivity to scratches, variability with screen coatings, and, for some types, limited stylus support.

Recent trends focus on integrating touch sensing into display panels (projected capacitive touch on LCD or OLED), supporting high-resolution touch, and enabling advanced gestures. The technology also adapts to wearables and flexible or curved displays, expanding touchpanels into non-traditional form factors.