USE OF RESISTIVE TOUCH SCREEN AS A PROXIMITY SENSOR
First Claim
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1. A touch screen proximity sensing apparatus comprising:
- a touch screen comprising a bottom layer and a top layer wherein the top layer and bottom layer are oriented such that they are separate but capable of being temporarily pressed together;
a control circuit operatively connected to the touch screen;
a plurality of measurement circuits comprising;
a first measurement circuit comprising a resistive sensor circuit; and
a second measurement circuit comprising a proximity capacitance sensor circuit;
wherein the proximity capacitance sensor detects an object by determining an equivalent capacitance between the touch screen and the object;
wherein the resistive sensor circuit measures a touch position by measuring a voltage along a voltage gradient on at least one of the top layer and bottom layer; and
wherein the control circuit selectively connects the touch screen with at least one of the plurality of measurement circuits.
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Abstract
An apparatus and method for the use of a resistive touch screen as a proximity sensor. The touch screen operates in a touch sensing mode and a proximity sensing mode. The proximity sensing mode turns off the touch sensing circuit and uses the equivalent capacitor formed by the top layer of the touch screen with a nearby object to detect proximity. A control circuit selectively connects the touch screen with measurement circuits to perform each of the sensing functions. The control circuit can be implemented with timing based control or an event driven topology.
31 Citations
18 Claims
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1. A touch screen proximity sensing apparatus comprising:
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a touch screen comprising a bottom layer and a top layer wherein the top layer and bottom layer are oriented such that they are separate but capable of being temporarily pressed together; a control circuit operatively connected to the touch screen; a plurality of measurement circuits comprising; a first measurement circuit comprising a resistive sensor circuit; and a second measurement circuit comprising a proximity capacitance sensor circuit; wherein the proximity capacitance sensor detects an object by determining an equivalent capacitance between the touch screen and the object; wherein the resistive sensor circuit measures a touch position by measuring a voltage along a voltage gradient on at least one of the top layer and bottom layer; and wherein the control circuit selectively connects the touch screen with at least one of the plurality of measurement circuits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. In a system comprising a touch screen comprising a bottom layer and a top layer, and a plurality of measurement circuits comprising a capacitive proximity circuit and a resistive touch circuit,
a method for proximity detection using a resistive touch screen comprises the steps of: -
performing a resistive touch operation comprising the steps of; disabling the plurality of measurement circuits; operatively connecting the resistive touch circuit and the resistive touch screen; and measuring touch information obtained by the resistive touch screen; performing a proximity capacitive sensing operation comprising the steps of; disabling the plurality measurement circuits from the resistive touch screen; operatively connecting the capacitive proximity circuit and the touch screen; and measuring proximity information obtained by the resistive touch screen; generating a mode selection signal comprising a touch state and a proximity state; performing the resistive touch operation when the mode selection signal is in the touch state; and performing the proximity capacitive sensing when the mode selection signal is in the proximity state. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification