Capacitance detecting circuit and method, and fingerprint sensor using the same
First Claim
1. A capacitance detecting circuit for detecting changes in capacitances at intersections between a plurality of row lines and a column line as voltages, comprising:
- column-line driving means for driving the column line;
code generating means for generating code having orthogonality in chronological order;
selection synthesizing means for selecting a certain number of row lines from the plurality of row lines by using the code and for synthesizing measured voltages at the intersections between the selected row lines and the driven column line so as to output the synthesized measured voltage in chronological order; and
decoding computation means for separating the measured voltages corresponding to the capacitances at the intersections by performing product sum computation between the synthesized measured voltage and the code.
3 Assignments
0 Petitions
Accused Products
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.
-
Citations
11 Claims
-
1. A capacitance detecting circuit for detecting changes in capacitances at intersections between a plurality of row lines and a column line as voltages, comprising:
-
column-line driving means for driving the column line;
code generating means for generating code having orthogonality in chronological order;
selection synthesizing means for selecting a certain number of row lines from the plurality of row lines by using the code and for synthesizing measured voltages at the intersections between the selected row lines and the driven column line so as to output the synthesized measured voltage in chronological order; and
decoding computation means for separating the measured voltages corresponding to the capacitances at the intersections by performing product sum computation between the synthesized measured voltage and the code. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A capacitance detecting method for detecting changes in capacitances at intersections between a plurality of row lines and a column line as voltages, comprising:
-
a column-line driving step of driving the column line;
a code generating step of generating code having orthogonality in chronological order;
a selection synthesizing step of selecting a certain number of row lines from the plurality of row lines by using the code and for synthesizing measured voltages at the intersections between the selected row lines and the driven column line so as to output the synthesized measured voltage in chronological order; and
a decoding computation step of separating the measured voltages corresponding to the capacitances at the intersections by performing product sum computation between the synthesized measured voltage and the code.
-
Specification