Capacitance detecting circuit and method, and fingerprint sensor using the same
US7084645B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 10, 2004 |
| Grant date | Aug 1, 2006 |
| Priority date | — |
| Expiry date | Feb 15, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0446
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A capacitance detecting circuit includes a code generator for generating code having orthogonality in chronological order. A column-line driver drives the plurality of column lines based on the code by dividing the column lines into a first column line group and a second column line group. A capacitance detector, which is connected to the row line, converts the total of currents generated in capacitances at the intersections with the driven column lines into a voltage signal and outputs the converted voltage signal. A decoding computation unit determines the voltages corresponding to the capacitances at the intersections for each of the column line groups by performing product sum computation between the measured voltages and the code. The column-line driver drives the first column line group and the second column line group by complementary voltages according to the code or information indicating the inversion of the code.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.