Capacitance detecting circuit and method, and fingerprint sensor using the same
US7078918B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 10, 2004 |
| Grant date | Jul 18, 2006 |
| Priority date | — |
| Expiry date | Feb 9, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0446
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a capacitance detecting circuit, changes in capacitances at intersections between a plurality of row lines and a column line are detected as voltages. The capacitance detecting circuit includes a column-line driver for driving the column line. A code generator generates code having orthogonality in chronological order. A selection synthesizer selects a certain number of row lines from the plurality of row lines by using the code and synthesizes measured voltages at the intersections between the selected row lines and the driven column line so as to output the synthesized measured voltage. A decoding computation unit separates the measured voltages corresponding to the capacitances at the intersections by performing product sum computation between the synthesized measured voltage and the code.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.