Content deleted Content added
Fixing reference errors |
|||
Line 30:
Capacitive displacement sensors can be used to make very precise [[thickness]] measurements. Capacitive displacement sensors operate by measuring changes in position. If the position of a reference part of known thickness is measured, other parts can be subsequently measured and the differences in position can be used to determine the thickness of these parts.<ref name="LionCapThickness">[http://www.lionprecision.com/tech-library/appnotes/app-flash/f-cap-0030-thickness.html Capacitive Thickness Measurements], A tutorial on capacitive thickness measurements.</ref> In order for this to be effective using a single probe, the parts must be completely flat and measured on a perfectly flat surface. If the part to be measured has any [[curvature]] or [[deformity]], or simply does not rest firmly against the flat surface, the distance between the part to be measured and the surface it is placed upon will be erroneously included in the thickness measurement. This error can be eliminated by using two capacitive sensors to measure a single part. Capacitive sensors are placed on either side of the part to be measured. By measuring the parts from both sides, curvature and deformities are taken into account in the [[measurement]] and their effects are not included in the thickness readings.
The thickness of plastic materials can be measured with the material placed between two electrodes a set distance apart. These form a type of capacitor. The plastic when placed between the electrodes acts as a dielectric and displaces air (which has [[dielectric constant]] of 1, different
Capacitive sensors circuits can be constructed that are able to detect changes in capacitance on the order of a 10<sup>−5</sup> [[Farad|picofarads]] (10 attofarads).
| |||