Synaptics is a world leader in capacitive touch sensing technology. This technology is at the heart of our industry-standard TouchPad products. Since the introduction of the TouchPad, we have expanded our technology in a variety of directions including pen sensors, force sensors, and flexible touch sensors.
How the TouchPad Works
Synaptics TouchPad devices work by sensing an electrical property called capacitance. Whenever two electrically conductive objects come near to each other without touching, their electric fields interact to form capacitance. The surface of a TouchPad sensor is an array of conductive metal electrodes, covered by a protective insulating layer. The human finger is also an electrical conductor, and when you place your finger on a TouchPad, a tiny capacitance forms between your finger and the metal electrodes in the TouchPad. The insulating layer protects the TouchPad sensor from wear by preventing your finger from actually touching the sensor, and is textured to help your finger move smoothly across the surface.
The TouchPad sensor's sensitive analog electronics measure the amount of capacitance in each of the electrodes. By sensing when the capacitance increases, the TouchPad can tell when your finger is touching. By measuring which electrodes have the most capacitance, the TouchPad can also locate your finger to an accuracy of better than 1/1000th of an inch. The capacitive sensing ASIC chip incorporates a proprietary microprocessor that computes the finger's position and speed and reports them to the host computer in the form of cursor motion.
On a PC, the TouchPad can work with any mouse driver, but it works best with the Synaptics TouchPad driver. When used with the Synaptics driver, the TouchPad reports not just the mouse-like motion of the finger, but also the absolute position of the finger on the TouchPad surface as well as the amount of finger pressure. The driver uses this extra information to enhance the user interface in a variety of ways. For example, if the finger moves up and down along the right-hand edge of the pad, the driver activates the patented Virtual Scrolling feature.
In addition, a general purpose TouchPad Application Programming Interface (API) is available in the Customer Support-Developer's Support section of the web site, which allows adaptation of our TouchPad into other products. The underlying capacitive technology in the TouchPad can be developed for a wide variety of devices, such as cell phones, MP3 players, PDAs, touchscreens, and remote controls. Synaptics capacitive sensing technology has been used to provide 2D cursor control, 1D scrolling functionality, and replace electrical switches in many types of electronic devices.
Synaptics' capacitive sensing technology has numerous advantages over competing technologies like membrane switches and resistive sensors. Its solid-state construction makes it extraordinarily rugged. And because our capacitive sensor is so versatile, it can be made extremely thin, lightweight, flexible, or even transparent. The proprietary microprocessor makes it possible to build custom capacitive solution for special applications.
