Capacitance detector circuit, capacitance detection method, and fingerprint sensor using the same
US7075316B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 14, 2004 |
| Grant date | Jul 11, 2006 |
| Priority date | — |
| Expiry date | Sep 14, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C27/026
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A capacitance detecting circuit of a capacitive sensor having a plurality of column lines and a row line intersecting the column lines detects a change in capacitance at an intersection of a column line and a row line. The circuit includes a PN code generating unit for generating a code having orthogonality in time sequence to output the generated code as a column drive signal, a column line drive unit for driving a predetermined one of the column lines which are selected in response to the code, a capacitance detecting unit, connected to the row line, for detecting a voltage by converting a total sum of changes in capacitance at intersections of the selected column lines into the voltage to output the detected voltage, and a decode processing unit for performing a predetermined calculation on the detected voltage output from the capacitance detecting unit and the code to determine a voltage value responsive to the capacitance change at the intersection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.