Deconvolution-based capacitive touch detection circuit and method
First Claim
1. A capacitance measuring system comprising:
- (a) analog-digital circuitry coupled to row conductors and column conductors of a touch screen panel for producing a first digital signal representative of cross-coupling capacitances of the touch screen panel, the analog-digital circuitry including row drive circuitry which superimposes charge transfers from cross-coupling capacitances of at least a plurality of the row conductors to a first column conductor to cause the first digital signal to be a convoluted signal which is a function of the cross-coupling capacitances of at least the plurality of row conductors;
(b) calibration circuitry coupled to receive the first digital signal for subtracting base line data representing neutral values of the cross-coupling capacitances and subtracting the base line data from the first digital signal to produce a second digital signal which represents digital touch-induced capacitance change values caused by the presence of a touch near a cross-coupling capacitance of the touch screen panel; and
(c) a deconvolution circuit for deconvoluting the second digital signal to produce a third digital signal which represents a magnitude map of the touch-induced capacitance change values.
2 Assignments
0 Petitions
Accused Products
Abstract
A capacitance measuring system includes analog-digital circuitry (15) coupled to row conductors (2i) and column conductors (3i) of a touch screen panel (13A) for producing a first digital signal (DATA) representative of cross-coupling capacitances (CSENij). Row drive circuitry (45) superimposes charge transfers from cross-coupling capacitances of the row conductors to a first column conductor to cause the first digital signal to be a convoluted signal. Calibration circuitry (39,40) subtracts base line data from the first digital signal to produce a second digital signal (ΔDATA) representing touch-induced capacitance change values (ΔCSENIJ). A deconvolution circuit (44) deconvolutes the second digital signal to produce a digital output (58) representing a magnitude map of the touch-induced capacitance change values.
60 Citations
20 Claims
-
1. A capacitance measuring system comprising:
-
(a) analog-digital circuitry coupled to row conductors and column conductors of a touch screen panel for producing a first digital signal representative of cross-coupling capacitances of the touch screen panel, the analog-digital circuitry including row drive circuitry which superimposes charge transfers from cross-coupling capacitances of at least a plurality of the row conductors to a first column conductor to cause the first digital signal to be a convoluted signal which is a function of the cross-coupling capacitances of at least the plurality of row conductors; (b) calibration circuitry coupled to receive the first digital signal for subtracting base line data representing neutral values of the cross-coupling capacitances and subtracting the base line data from the first digital signal to produce a second digital signal which represents digital touch-induced capacitance change values caused by the presence of a touch near a cross-coupling capacitance of the touch screen panel; and (c) a deconvolution circuit for deconvoluting the second digital signal to produce a third digital signal which represents a magnitude map of the touch-induced capacitance change values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A method for measuring a capacitance, comprising:
-
(a) operating row drive circuitry of analog-digital circuitry coupled to row conductors and column conductors of a touch screen panel for producing a first digital signal representative of cross-coupling capacitances of the touch screen panel so as to superimpose charge transfers from cross-coupling capacitances of at least a plurality of the row conductors to a first column conductor thereby causing the first digital signal to be a convoluted signal which is a function of the cross-coupling capacitances of at least the plurality of row conductors; (b) producing a second digital signal which represents digital touch-induced capacitance change values caused by the presence of a touch near a cross-coupling capacitance of the touch screen panel by subtracting base line data representing the cross-coupling capacitances from the first digital signal; and (c) deconvoluting the second digital signal to produce a third digital signal which represents a magnitude map of the touch-induced capacitance change values. - View Dependent Claims (16, 17, 18, 19)
-
-
20. A system for measuring a capacitance, comprising:
-
(a) means coupled to row conductors and column conductors of a touch screen panel for producing a first digital signal representative of cross-coupling capacitances of the touch screen panel so as to superimpose charge transfers from cross-coupling capacitances of at least a plurality of the row conductors to a first column conductor thereby causing the first digital signal to be a convoluted signal which is a function of the cross-coupling capacitances of at least the plurality of row conductors; (b) means for producing a second digital signal which represents digital touch-induced capacitance change values caused by the presence of a touch near a cross-coupling capacitance of the touch screen panel by subtracting base line data representing the cross-coupling capacitance changes from the first digital signal; and (c) means for deconvoluting the second digital signal to produce a third digital signal which represents a magnitude map of the touch-induced capacitance change values.
-
Specification