Low-Power Capacitive Sensor Monitoring and Method
First Claim
1. A touch screen controller system for controlling a touch screen having a first number of first type conductors and a second number of second type conductors, comprising:
- (a) analog-digital circuitry coupled to the first type conductors and the second type conductors of a touch screen for producing a first digital signal representative of a self capacitance of one of the second type conductors during an element proximity scanning mode and also representative of mutual capacitances of the touch screen during an element location scanning mode, the analog-digital circuitry operating to superimpose charge transfers from mutual capacitances of one of the first type conductors to one of the second type conductors during the element location scanning mode, and also operating to produce information representative of the influence of an element on the self-capacitance during the element proximity scanning mode;
(b) calibration circuitry coupled to receive the first digital signal for calibrating the first digital signal with respect to base line data representing neutral values of the self capacitances during the element proximity scanning mode and for calibrating the first digital signal with respect to base line data representing neutral values of the mutual capacitances during the element location scanning mode to produce a second digital signal which may represent either element proximity induced self-capacitance change values during the element proximity scanning mode or element location induced mutual capacitance change values during the element location scanning mode;
(c) touch presence monitoring circuitry for operating on the second digital signal during the element proximity scanning mode to determine if the element is proximate to the touch screen; and
(d) a processing circuit for operating on the second digital signal during the element location scanning mode to produce a third digital signal which represents a magnitude map of element induced mutual capacitance change values.
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Accused Products
Abstract
A touch screen controller produces a first signal (DATA) representative of a self capacitance (Cselfj) of a touch screen (13A) during a presence scanning mode and representative of mutual capacitances (Cmij) of the screen during a location scanning mode. The first signal is calibrated during the presence scanning and during the location scanning to produce a second signal (ΔDATA) which may represent either self-capacitance changes (ΔCselfj) caused by proximity of an element (22) during presence scanning or mutual capacitance changes (ΔCmij) caused the element during location scanning. The second signal is operated upon during presence scanning to determine to determine proximity of the element relative to the screen and during location scanning to produce a magnitude map of the mutual capacitance changes.
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Citations
21 Claims
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1. A touch screen controller system for controlling a touch screen having a first number of first type conductors and a second number of second type conductors, comprising:
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(a) analog-digital circuitry coupled to the first type conductors and the second type conductors of a touch screen for producing a first digital signal representative of a self capacitance of one of the second type conductors during an element proximity scanning mode and also representative of mutual capacitances of the touch screen during an element location scanning mode, the analog-digital circuitry operating to superimpose charge transfers from mutual capacitances of one of the first type conductors to one of the second type conductors during the element location scanning mode, and also operating to produce information representative of the influence of an element on the self-capacitance during the element proximity scanning mode; (b) calibration circuitry coupled to receive the first digital signal for calibrating the first digital signal with respect to base line data representing neutral values of the self capacitances during the element proximity scanning mode and for calibrating the first digital signal with respect to base line data representing neutral values of the mutual capacitances during the element location scanning mode to produce a second digital signal which may represent either element proximity induced self-capacitance change values during the element proximity scanning mode or element location induced mutual capacitance change values during the element location scanning mode; (c) touch presence monitoring circuitry for operating on the second digital signal during the element proximity scanning mode to determine if the element is proximate to the touch screen; and (d) a processing circuit for operating on the second digital signal during the element location scanning mode to produce a third digital signal which represents a magnitude map of element induced mutual capacitance change values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17)
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16. A method for operating a touchscreen controller, the method comprising:
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(a) producing a first digital signal representative of a self capacitance of a second type conductor of a touch screen during an element proximity scanning mode and also representative of mutual capacitances of the touch screen during an element location scanning mode; (b) calibrating the first digital signal with respect to base line data representing neutral values of the self capacitances during the element proximity scanning mode and also calibrating the first digital signal with respect to base line data representing neutral values of the mutual capacitances during the element location scanning mode so as to produce a second digital signal which may represent either element proximity induced self-capacitance change values during the element proximity scanning mode or element location induced mutual capacitance change values during the element location scanning mode; (c) operating on the second digital signal during the element proximity scanning mode to determine proximity of the element relative to the touch screen; and (d) operating on the second digital signal during the element location scanning mode to produce a third digital signal which represents a magnitude map of the element location induced mutual capacitance change values. - View Dependent Claims (18, 19, 20)
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21. A touchscreen controller comprising:
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(a) means for producing a first digital signal representative of a self capacitance of a second type conductor of a touch screen during an element proximity scanning mode and also representative of mutual capacitances of the touch screen during an element location scanning mode; (b) means for calibrating the first digital signal with respect to base line data representing neutral values of the self capacitances during the element proximity scanning mode and also calibrating the first digital signal with respect to base line data representing neutral values of the mutual capacitances during the element location scanning mode so as to produce a second digital signal which may represent either element proximity induced self-capacitance change values during the element proximity scanning mode or element location induced mutual capacitance change values during the element location scanning mode; (c) means for operating on the second digital signal during the element proximity scanning mode to determine proximity of the element relative to the touch screen; and (d) means for operating on the second digital signal during the element location scanning mode to produce a third digital signal which represents a magnitude map of the element location induced mutual capacitance change values.
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Specification