System for extending the lifespan of a touch screen assembly
First Claim
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1. A system for extending the lifespan of a touch screen, the system comprising:
- a four wire touch screen assembly comprising a plurality of layers, the touch screen assembly having four output voltages that are related to a pressure exerted upon the touch screen assembly, wherein two of the four output voltages are related to the pressure exerted upon the touch screen assembly with respect to an x-dimension and the other two of the four output voltages are related to the pressure exerted upon the touch screen assembly with respect to a y- dimension, wherein the plurality of layers include;
an outer protective layer;
a resistive digitizer film, wherein the outer protective layer substantially covers and protects the resistive digitizer film; and
a digitizing element, wherein the resistive digitizer film is located between the outer protective layer and the digitizing element;
an analog multiplexer/demultiplexer having four input voltages and an output voltage, wherein the four input voltages of the analog multiplexer/demultiplexer are related to the four output voltages of the touch screen assembly;
a resistor configured to receive the output voltage of the analog multiplexer/demultiplexer such that a voltage across the resistor is equal to the output voltage of the analog multiplexer/demultiplexer;
a first capacitor coupled to a first wire carrying a first output voltage of the four output voltages, the first output voltage related to the pressure exerted upon the touch screen assembly with respect to the x-dimension, the first capacitor further coupled to a ground;
a second capacitor coupled to a second wire carrying a second output voltage of the four output voltages, the second output voltage related to the pressure exerted upon the touch screen assembly with respect to the y-dimension, the second capacitor further coupled to the ground;
a sensing circuit configured to measure the voltage across the resistor;
a comparator configured to perform operations including;
accessing the measured voltage across the resistor;
comparing the measured voltage across the resistor with a programmable threshold voltage; and
initiating a signal indicating that a valid touch has occurred when the measured voltage across the resistor is at least equal to the programmable threshold voltage; and
a controller configured to;
receive a hardware interrupt indicating that the pressure is being exerted upon the touch screen assembly; and
increase the programmable threshold voltage to account for a loss of tension of the resistive digitizer film.
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Abstract
Embodiments of the present invention recite a system for extending the lifespan of a touch screen assembly. In one embodiment, a signal is received indicating an input pressure is being applied to a touch screen assembly. It is then determined that the input pressure comprises a valid input event and the coordinates of the valid input event are received from the touch screen assembly.
15 Citations
10 Claims
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1. A system for extending the lifespan of a touch screen, the system comprising:
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a four wire touch screen assembly comprising a plurality of layers, the touch screen assembly having four output voltages that are related to a pressure exerted upon the touch screen assembly, wherein two of the four output voltages are related to the pressure exerted upon the touch screen assembly with respect to an x-dimension and the other two of the four output voltages are related to the pressure exerted upon the touch screen assembly with respect to a y- dimension, wherein the plurality of layers include; an outer protective layer; a resistive digitizer film, wherein the outer protective layer substantially covers and protects the resistive digitizer film; and a digitizing element, wherein the resistive digitizer film is located between the outer protective layer and the digitizing element; an analog multiplexer/demultiplexer having four input voltages and an output voltage, wherein the four input voltages of the analog multiplexer/demultiplexer are related to the four output voltages of the touch screen assembly; a resistor configured to receive the output voltage of the analog multiplexer/demultiplexer such that a voltage across the resistor is equal to the output voltage of the analog multiplexer/demultiplexer; a first capacitor coupled to a first wire carrying a first output voltage of the four output voltages, the first output voltage related to the pressure exerted upon the touch screen assembly with respect to the x-dimension, the first capacitor further coupled to a ground; a second capacitor coupled to a second wire carrying a second output voltage of the four output voltages, the second output voltage related to the pressure exerted upon the touch screen assembly with respect to the y-dimension, the second capacitor further coupled to the ground; a sensing circuit configured to measure the voltage across the resistor; a comparator configured to perform operations including; accessing the measured voltage across the resistor; comparing the measured voltage across the resistor with a programmable threshold voltage; and initiating a signal indicating that a valid touch has occurred when the measured voltage across the resistor is at least equal to the programmable threshold voltage; and a controller configured to; receive a hardware interrupt indicating that the pressure is being exerted upon the touch screen assembly; and increase the programmable threshold voltage to account for a loss of tension of the resistive digitizer film. - View Dependent Claims (2, 3, 4, 5)
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6. A sensor circuit for extending the lifespan of a touch screen, the sensor circuit comprising:
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an analog multiplexer/demultiplexer having four input voltages and an output voltage, wherein the four input voltages of the analog multiplexer/demultiplexer are related to four output voltages of a four wire touch screen assembly, wherein two of the four output voltages are related to the pressure exerted upon the touch screen assembly with respect to an x- dimension and the other two of the four output voltages are related to the pressure exerted upon the touch screen assembly with respect to a y-dimension, wherein the touch screen assembly comprises a plurality of layers including; an outer protective layer; a resistive digitizer film, wherein the outer protective layer substantially covers and protects the resistive digitizer film; and a digitizing element, wherein the resistive digitizer film is located between the outer protective layer and the digitizing element; a resistor configured to receive the output voltage of the analog multiplexer/demultiplexer such that a voltage across the resistor is equal to the output voltage of the analog multiplexer/demultiplexer; a first capacitor coupled to a first wire carrying a first output voltage of the four output voltages, the first output voltage related to the pressure exerted upon the touch screen assembly with respect to the x-dimension, the first capacitor further coupled to a ground; a second capacitor coupled to a second wire carrying a second output voltage of the four output voltages, the second output voltage related to the pressure exerted upon the touch screen assembly with respect to the y-dimension, the second capacitor further coupled to the ground; a sensing circuit configured to measure the voltage across the resistor; a comparator configured to perform operations including; accessing the measured voltage across the resistor; comparing the measured voltage across the resistor with a programmable threshold voltage; and initiating a signal indicating that a valid touch has occurred when the measured voltage across the resistor is at least equal to the programmable threshold voltage; and a controller configured to; receive a hardware interrupt indicating that the pressure is being exerted upon the touch screen assembly; and increase the programmable threshold voltage to account for a loss of tension of the resistive digitizer film. - View Dependent Claims (7, 8, 9, 10)
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Specification