Systems for an electrostatic stylus within a capacitive touch sensor
First Claim
1. A method for use with a two dimensional sensor array, the method comprising:
- in a transmission mode, configuring a device having a circuit and an electrode for transmitting a voltage to a node of the two dimensional sensor array coupled electrostatically to the electrode by;
generating a voltage using a switchmode power supply circuit, wherein the switchmode power supply circuit comprises at least an inductor and a diode, the diode being coupled to a transformer,permitting the diode to be intermittently forward-biased, and permitting current to flow through the diode into a stray capacitance, andconfiguring a switch to electrically isolate a component in the circuit; and
in a receiving mode, configuring the circuit for receiving the current through the node coupled to the electrode by;
configuring the switch to receive the current into the electrically isolated component in the circuit, andconfiguring the diode to be reversed-biased such that the component is electrically isolated from an inductance of the transformer in the switchmode power supply circuit; and
further in the receiving mode, configuring the circuit for determining a position of the electrode with respect to the two dimensional sensor array based on the received current.
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0 Petitions
Accused Products
Abstract
Systems are described for transmitting and receiving signals in an active stylus for a capacitive touch sensor, for which the systems have at least one circuit for receiving a current from an electrode and for transmitting a voltage onto the electrode. The systems include components for receiving the current in a receiving mode, a switch, and a switchmode power supply circuit having at least a transformer and a diode, for which the diode is coupled to the transformer. In a transmission mode, there is means for electrically isolating at least some of the components configured for receiving the current in the receiving mode from the voltage formed across the stray capacitance. In the receiving mode, there is a means for electrically isolating at least some of the components configured for receiving the current in the receiving mode from an inductance of the transformer in the switchmode power supply circuit.
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Citations
21 Claims
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1. A method for use with a two dimensional sensor array, the method comprising:
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in a transmission mode, configuring a device having a circuit and an electrode for transmitting a voltage to a node of the two dimensional sensor array coupled electrostatically to the electrode by; generating a voltage using a switchmode power supply circuit, wherein the switchmode power supply circuit comprises at least an inductor and a diode, the diode being coupled to a transformer, permitting the diode to be intermittently forward-biased, and permitting current to flow through the diode into a stray capacitance, and configuring a switch to electrically isolate a component in the circuit; and in a receiving mode, configuring the circuit for receiving the current through the node coupled to the electrode by; configuring the switch to receive the current into the electrically isolated component in the circuit, and configuring the diode to be reversed-biased such that the component is electrically isolated from an inductance of the transformer in the switchmode power supply circuit; and further in the receiving mode, configuring the circuit for determining a position of the electrode with respect to the two dimensional sensor array based on the received current. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for use with a two dimensional sensor array, the apparatus comprising:
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an electrode; components configured for receiving current in a receiving mode; a switchmode power supply circuit comprising at least a transformer and a diode, wherein the diode is coupled to the transformer; and a switch configured to switch between a receiving mode and a transmission mode; wherein in the transmission mode, a circuit for transmitting the voltage to the electrode is configured to; generate the voltage using the switchmode power supply circuit, permit the diode to be intermittently forward-biased, and for current to flow through the diode into a stray capacitance, and open the switch to electrically isolate at least some of the components configured for receiving the current in the receiving mode from the voltage formed across the stray capacitance; and in the receiving mode, the circuit for receiving the current from the electrode is configured to; close the switch to receive the current into the electrically isolated components configured for receiving the current, and permit the diode to be reversed-biased in the receiving mode such that at least some of the components configured for receiving the current in the receiving mode are electrically isolated from an inductance of the transformer in the switchmode power supply circuit; and further in the receiving mode, the circuit is configured to determine a position of the electrode with respect to the two dimensional sensor array based on the received current. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system for use with a two-dimensional sensor array, the system comprising:
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an electrode; components configured for receiving current in a receiving mode; a switchmode power supply circuit comprising at least a transformer and a diode, wherein the diode is coupled to the transformer; and a switch configured to switch between a receiving mode and a transmission mode; wherein in the transmission mode, a circuit for transmitting the voltage onto the electrode is configured to; generate the voltage using the switchmode power supply circuit, permit the diode to be intermittently forward-biased, and for current to flow through the diode into a stray capacitance, open the switch to electrically isolate at least some of the components configured for receiving the current in the receiving mode from the voltage formed across the stray capacitance; and in the receiving mode, the circuit for receiving the current from the electrode is configured to; close the switch to receive the current into the components configured for receiving the current in the receiving mode; electrically isolate at least some of the components configured for receiving the current in the receiving mode from an inductance of the transformer in the switchmode power supply circuit; and further in the receiving mode, the circuit is configured to determine a position of the electrode with respect to the two dimensional sensor array based on the received current. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification