구차니의 잡동사니 모음

Capacitive sensors can be constructed from many different media, such as copper, Indium tin oxide (ITO) and printed ink. Copper capacitive sensors can be implemented on standard FR4 PCBs as well as on flexible material. ITO allows the capacitive sensor to be up to 90% transparent (for single layer solutions). The size and spacing of the capacitive sensor are both very important to the sensor's performance. In addition to the size of the sensor, and its spacing relative to the ground plane, the type of ground plane used is very important. Since the parasitic capacitance of the sensor is related to the E-Field's path to ground, it is important to choose a ground plane that limits the concentration of E-Field lines without a conductive object present.

Designing a capacitance sensing system requires first picking the type of sensing material (FR4, Flex, ITO, etc). One also needs to understand the environment the device will operate in, such as the full operating temperature range, what radio frequencies are present and how the user will interact with the interface.

There are two types of capacitive sensing system. Transcapacitance, where the object (finger, conductive stylus) alters the transcapacitance coupling between row and column electrodes, which are scanned sequentially.^[3] The second is Absolute Capacitance where the object (finger, etc.) senses the presence and absolute position horizontally and vertically on the surface. Subtraction of a preceding absolute position from the present absolute position yields the relative motion of the object/finger during that time.

[링크 : http://en.wikipedia.org/wiki/Capacitive_sensing]