Touch screen detection and diagnostics
First Claim
1. A method comprising:
- driving a first current at a touch screen in response to a contact event to the touch screen, a magnitude of the first current based on a presence of the contact event to the touch screen;
generating a second current proportional to the first current via a first current mirror;
generating a voltage at a detection node based on the second current;
detecting the contact event based on the voltage at the detection node; and
determining whether the touch screen is shorted to a reference voltage based on whether the voltage at the detection node changes in response to a presence of the contact event at the touch screen.
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Accused Products
Abstract
A method includes driving a current through a touch screen that is based on contact of the touch screen, generating a proportional second current, and detecting contact of the touch screen from the second current. Another method includes providing a touch screen with parallel plates, disabling contact detection when a plate voltage is lower than a threshold voltage, and enabling contact detection when the plate voltage is at least equal to the threshold voltage. A device includes a first node and a second node coupled to a touch screen, a third node, a first current mirror coupled to the second node and the third node configured to generate a current at the third node that is proportional to a second current at the second node, and a detection circuit that provides a signal based on the first current that indicates contact of the touch screen.
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Citations
17 Claims
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1. A method comprising:
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driving a first current at a touch screen in response to a contact event to the touch screen, a magnitude of the first current based on a presence of the contact event to the touch screen; generating a second current proportional to the first current via a first current mirror; generating a voltage at a detection node based on the second current; detecting the contact event based on the voltage at the detection node; and determining whether the touch screen is shorted to a reference voltage based on whether the voltage at the detection node changes in response to a presence of the contact event at the touch screen. - View Dependent Claims (2, 3, 4, 16)
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5. A method comprising:
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providing a touch screen comprising a pair of parallel conductive plates; disabling detection of a contact event to the touch screen responsive to a select plate of the pair of parallel conductive plates having a voltage lower than a threshold voltage, wherein the contact event results in an electrical contact between the pair of parallel conductive plates; and enabling detection of a contact event to the touch screen responsive to the select plate having a voltage at least equal to the threshold voltage. - View Dependent Claims (6, 7, 8)
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9. A device comprising:
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a first node adapted to be coupled to an interface of a touch screen; a second node adapted to be coupled to the interface of the touch screen; a third node; a first current mirror coupled to the second node and the third node, the first current mirror configured to generate a first current at the third node that is proportional to a second current flowing through the touch screen from the first node to the second node; and a detection circuit adapted to provide a signal based on the first current, the signal indicating whether a contact event is present at the touch screen. - View Dependent Claims (10, 11, 12, 13, 14, 15, 17)
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Specification