METHODS AND SYSTEMS FOR GUARDING A CHARGE TRANSFER CAPACITANCE SENSOR FOR PROXIMITY DETECTION
First Claim
1. A controller configured to determine a measurable capacitance, the controller configured to:
- apply a pre-determined voltage to a first sensing electrode of a plurality of sensing electrodes using a first switch;
apply a first guard voltage to a guarding electrode using a second switch;
share charge between the first sensing electrode and a passive network, such that shared charge is accumulated on a filter capacitance of the passive network;
apply a second guard voltage different from the first guard voltage to the guarding electrode;
measure a voltage on the filter capacitance for a number of measurements equal to at least one to produce at least one result; and
determine the measurable capacitance using the at least one result.
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Accused Products
Abstract
Methods, systems and devices are described for determining a measurable capacitance for proximity detection in a sensor having a plurality of sensing electrodes and at least one guarding electrode. A charge transfer process is executed for at least two executions. The charge transfer process includes applying a pre-determined voltage to at least one of the plurality of sensing electrodes using a first switch, applying a first guard voltage to the at least one guarding electrode using a second switch, sharing charge between the at least one of the plurality of sensing electrodes and a filter capacitance, and applying a second guard voltage different from the first guard voltage to the at least one guarding electrode. A voltage is measured on the filter capacitance for a number of measurements equal to at least one to produce at least one result to determine the measurable capacitance for proximity detection.
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Citations
20 Claims
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1. A controller configured to determine a measurable capacitance, the controller configured to:
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apply a pre-determined voltage to a first sensing electrode of a plurality of sensing electrodes using a first switch; apply a first guard voltage to a guarding electrode using a second switch; share charge between the first sensing electrode and a passive network, such that shared charge is accumulated on a filter capacitance of the passive network; apply a second guard voltage different from the first guard voltage to the guarding electrode; measure a voltage on the filter capacitance for a number of measurements equal to at least one to produce at least one result; and determine the measurable capacitance using the at least one result. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A controller adapted to determine a capacitance value associated with a sensor electrode, the controller configured to:
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apply a guard signal to a guarding electrode, the guard signal comprising a waveform having at least two different voltages; determine the capacitance value by repeatedly applying a voltage to the sensor electrode, accumulating charge on an integrating capacitance by repeatedly sharing charge between the sensor electrode and the integrating capacitance, generating quantized values by repeatedly measuring a voltage on the integrating capacitance using a quantizer of the controller, repeatedly changing charge on the integrating capacitance based on the quantized values, and determining the capacitance value associated with the sensor electrode using the quantized values. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A controller including a memory, the memory including executable instructions for determining a measurable capacitance associated with a sensing electrode by:
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applying a guard signal to a guarding electrode, the guard signal comprising a waveform having at least two different voltages; applying a voltage to the sensing electrode; sharing charge between the sensing electrode and a passive network such that shared charge is accumulated on an integrating capacitance of the passive network; measuring a voltage on the integrating capacitance for a number of measurements equal to at least one to produce at least one result; and determining the measurable capacitance using the at least one result. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification