Capacitive proximity effect?

[Don A. Gilmore]

Hi guys:

I'm interested in how a capacitive sensor works, in general. I have a vauge
idea that the face of the sensor is theoretically like one plate of a
capacitor and that a high-frequency signal is applied to it somehow and that
an object that comes near the sensing face will change the dielectric and
cause a fluctuation of *something*, but I don't know anything more specific
than that.

Could someone point me in the direction of a website or book that explains
this phenomenon with some explanatory schematics? Or maybe one of you
bright fellas can enlighten me.

Thanks for any help you can provide.

Don A. Gilmore
Mechanical Engineer
Kansas City, Mo.

 

[John Popelish]

"Don A. Gilmore" wrote:

Hi guys:

I'm interested in how a capacitive sensor works, in general. I have a vauge
idea that the face of the sensor is theoretically like one plate of a
capacitor and that a high-frequency signal is applied to it somehow and that
an object that comes near the sensing face will change the dielectric and
cause a fluctuation of *something*, but I don't know anything more specific
than that.

Could someone point me in the direction of a website or book that explains
this phenomenon with some explanatory schematics? Or maybe one of you
bright fellas can enlighten me.

Thanks for any help you can provide.

The theory is a bit thin, but the pictures are nice:
http://www.enm.com/training/siemenscourses/snrs_3.pdf

Another rather weak reference:
http://www.ab.com/sensors/sensorstoday/pdfs/FSM-900-2.pdf



--
John Popelish