Active stylus self-capacitance measurement
First Claim
1. A method comprising:
- modifying an amount of charge of a capacitance of a touch sensor, the modified amount of charge resulting in a voltage at the capacitance being a first pre-determined voltage level;
applying a first pre-determined amount of charge to the capacitance, the application of the first pre-determined amount of charge to the capacitance modifying the voltage at the capacitance from the first pre-determined voltage level to a first charging voltage level;
determining a first voltage at a sampling capacitor, the first voltage being proportional to a difference between the first charging voltage level and a reference voltage level;
applying, while holding the capacitance at the reference voltage level, a second pre-determined amount of charge to the capacitance by a first edge of a signal transmitted by a stylus, wherein applying the first predetermined amount of charge comprises applying a first amount of current to the capacitance prior to receiving the first edge of the signal transmitted by the stylus;
determining a second voltage at the sampling capacitor, the second voltage being proportional to the second pre-determined amount of charge; and
determining whether a touch and stylus input to the touch sensor has occurred based on the first voltage and the second voltage.
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Accused Products
Abstract
In one embodiment, a method includes modifying an amount of charge of a capacitance of a touch sensor. The modified amount of charge results in a voltage at the capacitance being a first pre-determined voltage level. The method also includes applying a first pre-determined amount of charge to the capacitance. The application of the first pre-determined amount of charge to the capacitance modifies the voltage at the capacitance from the first pre-determined voltage level to a first charging voltage level. The method also includes determining a first voltage at a sampling capacitor. The first voltage is proportional to a difference between the first charging voltage level and a reference voltage level. The method also includes determining whether a touch and stylus input to the touch sensor has occurred based on the first voltage and a second voltage.
26 Citations
20 Claims
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1. A method comprising:
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modifying an amount of charge of a capacitance of a touch sensor, the modified amount of charge resulting in a voltage at the capacitance being a first pre-determined voltage level; applying a first pre-determined amount of charge to the capacitance, the application of the first pre-determined amount of charge to the capacitance modifying the voltage at the capacitance from the first pre-determined voltage level to a first charging voltage level; determining a first voltage at a sampling capacitor, the first voltage being proportional to a difference between the first charging voltage level and a reference voltage level; applying, while holding the capacitance at the reference voltage level, a second pre-determined amount of charge to the capacitance by a first edge of a signal transmitted by a stylus, wherein applying the first predetermined amount of charge comprises applying a first amount of current to the capacitance prior to receiving the first edge of the signal transmitted by the stylus; determining a second voltage at the sampling capacitor, the second voltage being proportional to the second pre-determined amount of charge; and determining whether a touch and stylus input to the touch sensor has occurred based on the first voltage and the second voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A computer-readable non-transitory storage medium embodying logic configured when executed to:
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modify an amount of charge of a capacitance of a touch sensor, the modified amount of charge resulting in a voltage at the capacitance being a first pre-determined voltage level; apply a first pre-determined amount of charge to the capacitance, the application of the first pre-determined amount of charge to the capacitance modifying the voltage at the capacitance from the first pre-determined voltage level to a first charging voltage level; determine a first voltage at a sampling capacitor, the first voltage being proportional to a difference between the first charging voltage level and a reference voltage level; apply, while holding the capacitance at the reference voltage level, a second pre-determined amount of charge to the capacitance by a first edge of a signal transmitted by a stylus, wherein applying the first predetermined amount of charge comprises applying a first amount of current to the capacitance prior to receiving the first edge of the signal transmitted by the stylus; determine a second voltage at the sampling capacitor, the second voltage being proportional to the second pre-determined amount of charge; and determine whether a touch and stylus input to the touch sensor has occurred based on the first and the second voltage. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A device comprising:
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a measurement circuit; and a computer-readable non-transitory storage medium coupled to the measurement circuit and embodying logic configured when executed to; modify an amount of charge of a capacitance of a touch sensor, the modified amount of charge resulting in a voltage at the capacitance being a first pre-determined voltage level; apply a first pre-determined amount of charge to the capacitance, the application of the first pre-determined amount of charge to the capacitance modifying the voltage at the capacitance from the first pre-determined voltage level to a first charging voltage level; determine a first voltage at a sampling capacitor, the first voltage being proportional to a difference between the first charging voltage level and a reference voltage level; apply, while holding the capacitance at the reference voltage level, a second pre-determined amount of charge to the capacitance by a first edge of a signal transmitted by a stylus, wherein applying the first predetermined amount of charge comprises applying a first amount of current to the capacitance prior to receiving the first edge of the signal transmitted by the stylus; determine a second voltage at the sampling capacitor, the second voltage being proportional to the second pre-determined amount of charge; and determine whether a touch and stylus input to the touch sensor has occurred based on the first and the second voltage. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification