This page is about capacitive sensing methods.
For information about capacitors in general, see the Capacitor page.
Capacitive sensing is a widely used technique for proximity detection, touch-screens, level measurement, and distance measurements. It is used in the more expensive touch-screens found in today’s smart phones (as opposed to the cheaper and poorer performing resistive touch screens), for contact-less buttons (see page on Capacitive Touch Sensing), the distance measuring mechanism in digital calipers, liquid level measurement and much more.
- Level measurement
- Proximity sensing
- Impurity detection
- Touch sensing (see page on Capacitive Touch Sensing)
- Flow sensing
- Position sensing
Linear capacitive sensors measure a linear position change (i.e. not rotational).
The following image shows the typical dimensions of the linear encoder typically used in digital calliper design.
Rotational capacitive sensors can be used in similar situations to those that use optical encoders.
Examples of two small capacitive encoders.
PSoC chips with built in cap-sense hardware.
AD7150 with Er compensation
|Section 3.1 of the “Basic Linear Design” book by Analog Devices. Freely available from http://www.analog.com/library/analogDialogue/archives/43-09/linear_circuit_design_handbook.html|