Correction of parasitic capacitance effect in touch sensor panels
First Claim
1. A method for compensating for negative pixel effects on a touch sensor panel, comprising:
- estimating an object-to-ground capacitance of an object in contact with the touch sensor panel, wherein the estimation is made by simultaneously stimulating a plurality of drive lines to obtain a first measurement and simultaneously stimulating a plurality of sense lines to obtain a second measurement; and
determining an effective pixel touch output value for each pixel of the touch sensor panel based on the estimated object-to-ground capacitance and measured pixel touch output values when the estimated object-to-ground capacitance is at or below a predetermined threshold.
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Accused Products
Abstract
Compensation of pixels included in a touch sensor panel that generate erroneous readings (so called “negative pixels”) due to a poor grounding condition of the object touching the touch sensor panel is disclosed herein. To compensate for the erroneous readings, sense lines of the touch sensor panel can include reverse driving circuits to facilitate calculation of an object-to-ground capacitance. If the calculated object-to-ground capacitance indicates the presence of a poor grounding condition, then the object-to-ground capacitance and detected pixel touch output values are used to estimate new pixel touch output values that are used instead of the detected pixel touch output values to determine touch event(s).
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Citations
30 Claims
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1. A method for compensating for negative pixel effects on a touch sensor panel, comprising:
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estimating an object-to-ground capacitance of an object in contact with the touch sensor panel, wherein the estimation is made by simultaneously stimulating a plurality of drive lines to obtain a first measurement and simultaneously stimulating a plurality of sense lines to obtain a second measurement; and determining an effective pixel touch output value for each pixel of the touch sensor panel based on the estimated object-to-ground capacitance and measured pixel touch output values when the estimated object-to-ground capacitance is at or below a predetermined threshold. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for compensating for negative pixel effects on a touch sensor panel, comprising:
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a first stimulation signal source coupled to each of a plurality of drive lines having a first orientation on the touch sensor panel, the first stimulation signal sources configured for being activated to generate first measured pixel touch output values; a sense amplifier coupled to each of a plurality of sense lines having a second orientation different from the first orientation on the touch sensor panel, the sense amplifier including a second stimulation signal source coupled to an input of the sense amplifier, the second stimulation signal sources configured for being activated to generate second measured pixel touch output values; and a panel processor configured for calculating object-to-ground capacitance using the first and second measured pixel touch output values and determining effective pixel touch output values from use of the first measured pixel touch output values and an estimated object-to-ground capacitance when the object-to-ground capacitance is at or below a predetermined threshold. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A system for compensating for negative pixel effects on a touch sensor panel, comprising:
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a touch sensor panel having a plurality of drive lines and a plurality of sense lines; a panel subsystem coupled to the touch sensor panel, the panel subsystem including driver logic coupled to the drive lines of the touch sensor panel, the driver logic configured for generating first stimulation signals, and sense channels coupled to the sense lines of the touch sensor panel, each sense channel including a sense amplifier having a second stimulation signal source coupled to an input of the sense amplifier, the sense channels configured for generating first measured pixel touch output values in response to the first stimulation signals from the driver logic and generating second measured pixel touch output values in response to second stimulation signals from the second stimulation signal sources; and a panel processor coupled to the panel subsystem and configured for estimating an object-to-ground capacitance of an object in contact with the touch sensor panel wherein the estimation is made by simultaneously stimulating the drive lines to obtain a first measurement and simultaneously stimulating the sense lines to obtain a second measurement; and the panel processor further configured to determine an effective pixel touch output value for each pixel of the touch sensor panel based on the the estimated object-to-ground capacitance and measured pixel touch values when the estimated object-to-ground capacitance is below a predetermined threshold. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A non-transitory computer-readable medium comprising program code for compensating for negative pixel effects on a touch sensor panel, the program code for causing performance of a method comprising:
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periodically estimating an existence of a poor grounding condition of an object in contact with the touch sensor panel by estimating an object-to-ground capacitance of an object in contact with the touch sensor panel, wherein the estimation is made by simultaneously stimulating a plurality of drive lines to obtain a first measurement and simultaneously stimulating a plurality of sense lines to obtain a second measurement; and if the poor grounding condition exists, iteratively calculating an effective reduction in charge coupling of the object in contact with the touch sensor panel for each pixel using detected reduction in charge coupling for each pixel from sense amplifiers coupled to sense lines and an estimated ground capacitance indicative of the poor grounding condition. - View Dependent Claims (23, 24, 25, 26)
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27. A mobile telephone including a touch sensor panel and configured to provide negative pixel compensation to the touch sensor panel, comprising:
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a first stimulation signal source coupled to each of a plurality of drive lines having a first orientation on the touch sensor panel, the first stimulation signal sources configured for being activated to generate first measured pixel touch output values; a sense amplifier coupled to each of a plurality of sense lines having a second orientation different from the first orientation on the touch sensor panel, the sense amplifier including a second stimulation signal source coupled to an input of the sense amplifier, the second stimulation signal sources configured for being activated to generate second measured pixel touch output values; and a panel processor configured for estimating an object-to-ground capacitance of an object in contact with the touch sensor panel wherein the estimation is made by simultaneously stimulating the drive lines to obtain a first measurement and simultaneously stimulating the sense lines to obtain a second measurement; and the panel processor further configured for determining effective pixel touch output values from iterative use of the first measured pixel touch output values and the estimated object-to-ground capacitance when the estimated object-to-ground capacitance is below a predetermined threshold.
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28. A media player including a touch sensor panel and configured to provide negative pixel compensation to a touch sensor panel, comprising:
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the touch sensor panel having a plurality of drive lines and a plurality of sense lines; a panel subsystem coupled to the touch sensor panel, the panel subsystem including driver logic coupled to the drive lines of the touch sensor panel, the driver logic configured for generating first stimulation signals, and sense channels coupled to the sense lines of the touch sensor panel, each sense channel including a sense amplifier having a second stimulation signal source coupled to an input of the sense amplifier, the sense channels configured for generating first measured pixel touch output values in response to the first stimulation signals from the driver logic and generating second measured pixel touch output values in response to second stimulation signals from the second stimulation signal sources; and a panel processor coupled to the panel subsystem and configured for estimating an object-to-ground capacitance of an object in contact with the touch sensor panel wherein the estimation is made by simultaneously stimulating the drive lines to obtain a first measurement and simultaneously stimulating the sense lines to obtain a second measurement; and the panel processor further configured to determine an effective pixel touch output value for each pixel of the touch sensor panel based on the the estimated object-to-ground capacitance and measured pixel touch values when the estimated object-to-ground capacitance is below a predetermined threshold.
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29. A computing system including a touch sensor panel and configured to provide negative pixel compensation to the touch sensor panel, comprising:
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a first stimulation signal source coupled to each of a plurality of drive lines having a first orientation on the touch sensor panel, the first stimulation signal sources configured for being activated to generate first measured pixel touch output values; a sense amplifier coupled to each of a plurality of sense lines having a second orientation different from the first orientation on the touch sensor panel, the sense amplifier including a second stimulation signal source coupled to an input of the sense amplifier, the second stimulation signal sources configured for being activated to generate second measured pixel touch output values; and a panel processor configured for estimating an object-to-ground capacitance of an object in contact with the touch sensor panel wherein the estimation is made by simultaneously stimulating the drive lines to obtain a first measurement and simultaneously stimulating the sense lines to obtain a second measurement; and the panel processor further configured for determining effective pixel touch output values from iterative use of the first measured pixel touch output values and the estimated object-to-ground capacitance when the estimated object-to-ground capacitance is below a predetermined threshold. - View Dependent Claims (30)
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Specification