发明名称 |
Distance measurement with capacitive sensor |
摘要 |
Circuits and methods to read out capacitive sensors for distance measurement used by a position control system having a high accuracy and low noise have been disclosed. The ratio or difference of the capacitances of two sensor capacitors is used to determine the distance of an object from a target position. A sense amplifier is using auto-zero methods to achieve a long term stability. A sample-and-hold circuit using double correlated sampling methods minimizes noise. Low cost capacitors can be used with the sample-and-hold circuit because not the absolute value of capacitances but only the ratio of capacitances are relevant. A high resolution is ensured also by significant over-sampling of the control loop. |
申请公布号 |
US8076948(B2) |
申请公布日期 |
2011.12.13 |
申请号 |
US20080290386 |
申请日期 |
2008.10.30 |
申请人 |
KNOEDGEN HORST;KRONMUELLER FRANK;DIGITAL IMAGING SYSTEMS GMBH |
发明人 |
KNOEDGEN HORST;KRONMUELLER FRANK |
分类号 |
G01B7/14;G01D5/241 |
主分类号 |
G01B7/14 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|