Pressure Sensing Display Device

Abstract

A pressure sensing architecture for use with liquid crystal (LC), organic light emitting diode (OLED), electrophoretic, or other similarly fabricated displays. The described architecture includes a bottom TFT structure and a top structure with color filter material, and with liquid crystal, electrophoretic or OLED material provided in between. A piezoelectric or equivalent material is provided within the display assembly. Transmitting and receiving electrodes can be used to electrically bias the piezoelectric or equivalent material, which provides an analog electrical signal in response to incident touch pressure.

What is claimed is: 
     
         1 . A pressure sensing display device, cornprising:
 a cover layer;   a base layer;   a plurality of display pixels provided above the base layer and below the cover layer;   plurality of pressure sensing elements provided above the base layer, each of the pressure sensing elements including an electrode and a pressure sensitive layer adjacent to electrode, wherein each of the pressure sensing elements is configured to convert a pressure of a force applied to the pressure sensing element into an sensed output at the electrode based on the force applied to the pressure sensing element, wherein the sensed output is generated at least in part by a piezoelectric effect from deformation of the pressure the sensitive lasyer; and,   at least one detection circuit comprising:   an integrator having an integrator input coupled to the electrode of at least one of the plurality of pressure sensing elements and an integrator output, wherein the integrator provides an integrated value of the sensed output of at least one of the plurality of pressure sensing elements on the integrator output;   a detection line for providing a current;   an addressing switch having a switch input coupled to the integrator output and a switch output coupled to the detection line, wherein the addressing switch is addressable to be switched off to disconnect the integrator output from the detection line and cause the integrator to store a charge generated by the sensed output of the at least one of the plurality of pressure sensing elements as the integrated value, and addressable to be switched on and provide the integrated value on the integrator output to the switch output, wherein the stored charge is proportional to the pressure of a force applied to the at least one of the plurality of pressure sensing elements; and,   a charge amplifier having an amplifier output and, an amplifier input coupled to the switch output and to the detection line, the detection line providing the current to the charge amplifier input, wherein when the addressing switch is in the on state, the integrator output is connected to the detection line and an increase in the current at the detection line at the input of the charge amplifier caused by the integrated value causes a change in the voltage on the amplifier output indicative of the force causing the sensed output on the at least one of the plurality of pressure sensing elements.   
     
     
         2 . The device of  claim 1 , wherein an integrated circuit layer is provided above the base layer and the integrated circuit layer comprises a thin film transistor circuit. 
     
     
         3 . The device of  claim 1 , wherein the electrode of each pressure sensing element comprises a pressure sensing electrode and each of the plurality of display pixels includes a pixel electrode, and wherein at least one pixel electrode from the plurality of display pixels serves as both a pixel electrode and a pressure sensing electrode of one of the plurality of pressure sensing elements. 
     
     
         4 . The device of  claim 1 , wherein the device comprises a display assembly that includes the cover layer, the base layer, the plurality of display pixels and the plurality of pressure sensing elements, and wherein the at least one detection circuit is separated from the display assembly. 
     
     
         5 . The device of  claim 1 , wherein each pressure sensing element is formed from a portion of the pressure sensitive layer adjacent to the electrode. 
     
     
         6 . The device of  claim 1 , wherein the device further comprises a glass layer and the plurality of pressure sensing elements are provided above the glass layer. 
     
     
         7 . The device of  claim 1 , wherein the pressure sensing elements are provided in a layer above the display pixels. 
     
     
         8 . The device of  claim 1 , wherein the pressure sensing elements are provided in a layer below the display pixels. 
     
     
         9 . The device of  claim 1 , wherein the pressure sensing elements are substantially co-planar with the display pixels. 
     
     
         10 . The device of  claim 1 , wherein the display pixels are arranged in a grid, and wherein the pressure sensing elements replace display pixels in the grid at selected intervals. 
     
     
         11 . The device of  claim 1 , wherein the display pixels are arranged in a first grid, and wherein the pressure sensing elements are arranged in a second grid. 
     
     
         12 . The device of  claim 11 , wherein the second grid corresponds to the first grid. 
     
     
         13 . The device of  claim 1 , wherein the detection circuit further comprises:
 a reset transistor coupled to the electrode of the at least one of the plurality of pressure sensing elements wherein the sensed output is resettable by the reset transistor.   
     
     
         14 . The device of  claim 1 , wherein the detection circuit further comprises:
 a correlated double sampler configured to perform correlated double sampling on a signal based on the sensed output.   
     
     
         15 . The device of  claim 1 , further comprising a controller, wherein the controller detects a blanking interval of die display pixels, and wherein the addressing switch is addressed to be switched on during the blanking interval. 
     
     
         16 . The device of  claim 15 , wherein the blanking interval is a horizontal blanking interval. 
     
     
         17 . The device of  claim 15 , wherein the blanking interval is a vertical blanking interval. 
     
     
         18 . The device of  claim 15 , wherein the blanking interval is selectively determined by the controller between a horizontal and a vertical blanking interval. 
     
     
         19 . A method of pressure sensing in a display device comprising:
 providing a plurality of display pixels provided above a base layer and below a cover layer of the display device;   providing a plurality of pressure sensing elements above the base layer, each of the pressure sensing elements including an electrode and a pressure sensitive layer adjacent to the electrode;   converting a pressure of a force applied to at least one pressure sensing element of the plurality of pressure sensing elements into a sensed force output at the electrode of the at least one pressure sensing element based on the force, wherein the sensed force output is generated by a piezoelectric effect from deformation of the pressure sensitive layer included in the at least one pressure sensing element;   integrating the sensed force output of the at least one pressure sensing element using an integrator to provide an integrated value of the force sensed force output on an output of the integrator;   addressing the at least one the pressure sensing elements to provide the sensed force output by turning off an addressing switch to disconnect the output of the integrator from an output of the addressing switch and cause the integrator to store a charge generated by the force sensed force output of the at least one pressure sensing element as the integrated value, and turning on the addressing switch to provide the integrated value on the output of the integrator to a the output of the addressing switch, wherein the stored charge is proportional to the pressure of a force applied to the at least one of the plurality of pressure sensing elements; and,   providing a current on a detection line to an input of a charge amplifier that is coupled to the output of the addressing switch and the detection line, the detection line providing the current to the charge amplifier input, wherein when the addressing switch is in the on state, the integrator output is connected to the detection line and an increase in the current at the detection line at the input of the charge amplifier caused by the integrated value causes a change in the voltage on the amplifier output indicative of the force causing the sensed output on the at least one of the plurality of pressure sensing elements.