Interface circuitry for interconnecting touch tablet with a computer interface
First Claim
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1. A voltage interface circuit for interconnecting a source of positional data with internal circuitry of a computer interface containing at least one internal capacitor comprising:
- means for acquiring a voltage representation of at least a portion of positional data being supplied by said source of positional data;
means for providing an output signal which increases linearly in a selected time period from a first selected value to a second selected value;
means for detecting when said output signal equals said voltage representation; and
means, responsive to said means for detecting, for charging a selected one of said at least one internal capacitors above a given threshold voltage in response to the value of said output signal becoming equal to said voltage representation.
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Abstract
Interface circuitry is provided for interconnecting a source of positional data such as a touch tablet with a computer interface. The circuitry acquires voltages from the source of positional data which represent the data. An acquired voltage is compared with a ramped voltage. At the time of crossover the internal capacitor of the computer interface is rapidly charged above the threshold level to provide positional data from the external source to the computer interface.
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Citations
15 Claims
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1. A voltage interface circuit for interconnecting a source of positional data with internal circuitry of a computer interface containing at least one internal capacitor comprising:
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means for acquiring a voltage representation of at least a portion of positional data being supplied by said source of positional data; means for providing an output signal which increases linearly in a selected time period from a first selected value to a second selected value; means for detecting when said output signal equals said voltage representation; and means, responsive to said means for detecting, for charging a selected one of said at least one internal capacitors above a given threshold voltage in response to the value of said output signal becoming equal to said voltage representation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for operating an interface circuit which transfers positional data from an external source to a computer interface, comprising:
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acquiring a voltage represention of positional data from said source; providing an output signal which increases linearly in a selected time period from a first selected value to a second selected value; detecting when said output signal equals said voltage representation, and signaling said computer interface when said output signal equals said voltage representation.
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Specification