SENSOR AND METHOD OF SENSING
First Claim
1. An apparatus, comprising:
- a plurality of charge measurement capacitors to couple to a plurality of channels of a touch sensor; and
a controller configured to controltransferring charge to each of the plurality of channels,coupling each of the plurality of charge measurement capacitors to one of the plurality of channels such that charge is transferred to each of the plurality of charge measurement capacitors,discharging each of the plurality of charge measurement capacitors,determining an amount of charge present on each of the plurality of charge measurement capacitors; and
identifying a change in capacitance of any one of the plurality of channels based on the amount of charge.
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Accused Products
Abstract
A touch sensor senses the presence of an object at one of a plurality of channels on a surface of the touch sensor, wherein proximity of the object to the touch sensor results in a change in capacitance at the position of the channel. The touch sensor includes a drive circuit and a charge sensing circuit, each coupled to each of the channels. The charge sensing circuit includes at least one charge measurement capacitor. A measurement cycle is applied to the touch sensor having a drive portion and a sense portion. During the drive portion a charge is applied to the channels and therefore the charge measurement capacitors of the touch sensor, and during a sense portion the charge measurement capacitors are discharged by a predetermined amount and the remaining charge on the charge measurement capacitors is measured.
49 Citations
21 Claims
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1. An apparatus, comprising:
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a plurality of charge measurement capacitors to couple to a plurality of channels of a touch sensor; and a controller configured to control transferring charge to each of the plurality of channels, coupling each of the plurality of charge measurement capacitors to one of the plurality of channels such that charge is transferred to each of the plurality of charge measurement capacitors, discharging each of the plurality of charge measurement capacitors, determining an amount of charge present on each of the plurality of charge measurement capacitors; and identifying a change in capacitance of any one of the plurality of channels based on the amount of charge. - View Dependent Claims (2, 3, 4)
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5. Control circuitry configured to:
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cause measurement capacitors of a touch sensitive device to be contemporaneously discharged by a predetermined amount; cause sequential discharge of each charge measurement capacitor to determine an amount of charge present on each charge measurement capacitor following the discharge by the predetermined amount; and identify a change in capacitance of a plurality of channels of the touch sensitive device resulting from presence of an object at one of the plurality of channels.
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6. A touch sensor for sensing a presence of a body at one of a plurality of positions on a surface of the touch sensor, each position corresponding to a channel, the presence of the body being determined as a result of a change in capacitance of the channel, the touch sensor comprising:
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a drive circuit coupled to each of the channels, for each of the channels, a charge sensing circuit, each of the charge sensing circuits including a charge measurement capacitor; and a controller coupled to the drive circuit and the charge sensing circuit, the controller being operable to control the drive circuit to induce charge onto each of the channels during a drive part of a measurement cycle, to control each of the charge sensing circuits to couple the charge measurement capacitor respectively to one of the channels during a charge measurement part of the measurement cycle such that the charge induced onto the one of the channels during the drive part of the measurement cycle is transferred to a respective charge measurement capacitor, and to determine an amount of charge present on each of the signal measurement capacitors of the charge sensing circuits in sequence, by discharging the measurement capacitors, wherein the signal measurement capacitor of each of the charge sensing circuits is discharged contemporaneously by a predetermined amount, before an amount of charge remaining on each of the signal measurement capacitors is determined in sequence to identify whether there has been a change in the capacitance of the channel as a result of the presence of the body. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A method of sensing a presence of an object at one of a plurality of positions on a surface of a touch sensor, each of the plurality of positions corresponding to one of a plurality of channels, the presence of the object being determined as a result of a change in capacitance of at least one of the plurality of channels, the method comprising:
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controlling a drive circuit coupled to each of the plurality of channels to induce charge onto each of the plurality of channels during a drive part of a measurement cycle; controlling a charge sensing circuit for each of the plurality of channels to couple a charge measurement capacitor respectively to the each of the plurality of channels during a charge measurement part of the measurement cycle to the effect that the charge induced on the at least one of the plurality of channels during the drive part of the measurement cycle is transferred to at least one respective capacitor of the charge measurement capacitors of the charge sensing circuits; and determining an amount of charge present on each of the charge measurement capacitors of the charge sensing circuits in sequence by discharging the charge measurement capacitors in sequence, wherein the determining the amount of charge present on each of the charge measurement capacitors includes discharging contemporaneously each of the charge measurement capacitors by a predetermined amount before determining an amount of charge remaining on each of the charge measurement capacitors in sequence to identify whether there has been a change in the capacitance of at least one of the plurality of channels as a result of the presence of the object. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A touch sensitive control panel comprising:
a channel matrix comprising a first plurality of drive lines having N drive lines, a second plurality of sense lines, having M sense lines, wherein the channel matrix includes a number of channels equal to N multiplied by M, each of the channels being arranged to sense the presence of an object, each of the channels being disposed adjacent a respective intersection of one of the N drive lines and one of the M sense lines, each of the channels comprising a drive plate (X) connected to one of the N drive lines and a receiving plate (Y) connected to one of the M sense lines, each of the N drive lines is connected to a respective drive circuit, each of the M sense lines is connected to a respective charge sensing circuit including a charge measurement capacitor, and the channel matrix includes a controller, the controller being operable to; control each drive circuit to induce charge onto each drive plate of each of the M sense lines connected to each of the N drive lines during a drive part of a measurement cycle, control each charge sensing circuit to couple each charge measurement capacitor respectively to the receiving plate of each of the channels during a charge measurement part of the measurement cycle to the effect that the charge induced on each receiving plate of each channel during the drive part of the measurement cycle is transferred to each respective charge measurement capacitor, wherein each charge measurement capacitor of each charge sensing circuit is discharged contemporaneously by a predetermined amount, before, an amount of charge remaining on each charge measurement capacitor is determined in sequence to identify a change in capacitance of each channel as a result of the presence of the object.
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21. A method of sensing the presence of an object proximate a touch sensitive control panel, the touch sensitive control panel including a channel matrix comprising a first plurality of drive lines and a second plurality of sense lines, wherein the channels are disposed adjacent intersections of the drive lines and the sense lines, each channel comprises a drive plate connected to one of the drive lines and a receiving plate connected to one of the sense lines, each of the drive lines being connected to a respective drive circuit, and each of the sense lines being connected to a respective charge sensing circuit, each charge sensing circuit including a charge measurement capacitor, wherein the method comprises:
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controlling each drive circuit to induce charge onto each drive plate of each of the channels during a drive part of a measurement cycle, controlling each charge sensing circuit to couple each charge measurement capacitor respectively to each receiving plate of each of the channels during a charge measurement part of the measurement cycle to the effect that charge induced on each receiving plate of each channel during the drive part of the measurement cycle is transferred to each respective charge measurement capacitor, and discharging contemporaneously each charge measurement capacitor of each charge sensing circuit by a predetermined amount, before, determining an amount of charge remaining on each measurement capacitor in sequence, to identify a change in capacitance of each channel as a result of the presence of the object.
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Specification