POSITION SENSING DISPLAY

• US 20090179868A1
• Filed: 12/19/2008
• Published: 07/16/2009
• Est. Priority Date: 12/26/2007
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: TPO Displays Limited (InnoLux Corporation)
• Inventors: AYRES, John Richard, EDWARDS, Martin John
• Granted Patent: US 8,300,021 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A position sensing display integrates a touch sensor with an active matrix LCD panel. X sense electrodes and y sense electrodes in respective layers on a front panel are coupled capacitatively to respective sense circuits on active rear panel. A common electrode is driven, and the resulting signal on the x-sense electrodes and y sense electrodes is measured by the respective sense circuits. Changes in the resulting signal when sensed object approaches are measured to locate the sensed object.

Claims

1. An active matrix display, comprising:

a front panel and a rear panel;

wherein the front panel includes;

a transparent substrate;

a common electrode for cooperating with the rear panel for driving liquid crystal;

a plurality of sense electrodes extending across the display;

the rear panel includes;

a substrate; and

an array of display pixels arranged as rows and columns;

a plurality of sense circuits coupled to the respective sense electrodes; and

coupling capacitors capacitively coupling the sense electrodes to the respective sense circuits for coupling sense signals from the sense electrodes to the sense circuits.

2. The active matrix display according to claim 1, wherein the coupling capacitors comprise:

respective coupling electrodes connected to each of the sense electrodes on the front panel, the coupling electrodes extending beyond the common electrode to a coupling region; and

respective coupling electrodes connected to each of the sense circuits on the rear panel aligned with respective coupling electrodes on the front panel.

3. The active matrix display according to claim 1, wherein the sense electrodes include first sense electrodes and second sense electrodes extending across the first sense electrodes;

the front transparent substrate comprises;

a first sense electrode layer with one of the first sense electrodes and second sense electrodes and corresponding coupling electrodes on the front transparent substrate;

an insulating layer on the first sense electrode layer;

a second sense electrode layer with the other of the first sense electrodes and second sense electrodes and corresponding coupling electrodes on the insulating layer;

a filter layer including colour filters on the second sense electrode layer; and

a common electrode layer including the common electrode facing liquid crystal on the filter layer.

4. The active matrix display according to claim 3, wherein the first sense electrodes are x sense electrodes extending across the display in a column direction and the second sense electrodes are y sense electrodes extending across the display in a row direction.

5. The active matrix display according to claim 4, wherein the sense circuits include first sense circuits and second sense circuits, wherein the first sense circuits are arranged along one edge of the array of display pixels and the second sense circuits are arranged along a perpendicular edge of the array of display pixels.

6. The active matrix display according to claim 5, wherein the rear panel further comprises a row drive circuit arranged on the opposite edge of the array of display pixels to the second sense circuits and a column drive circuit arranged on the opposite edge of the array of display pixels to the first sense circuits.

7. The active matrix display according to claim 1, wherein the front panel for cooperating with the rear panel with sense circuits, comprises:

a common electrode for cooperating with the rear panel for driving the liquid crystal;

a plurality of first sense electrodes extending across the display in a first direction; and

a plurality of second sense electrodes extending across the display in a second direction across the first sense electrodes;

coupling electrodes connected to each of the first sense electrodes and second sense electrodes, the coupling electrodes extending beyond the common electrode to a coupling region for capacitively coupling to coupling electrodes on the rear panel for coupling capacitance sense signals from the sense electrodes to the sense circuits on the rear panel.

8. The active matrix display according to claim 7, wherein the front panel has:

a first sense electrode layer with one of the first sense electrodes and second sense electrodes and corresponding coupling electrodes on the front panel;

an insulating layer on the first sense electrode layer;

a second sense electrode layer with the other of the first sense electrodes and second sense electrodes and corresponding coupling electrodes on the insulating layer;

a filter layer including colour filters on the second sense electrode layer; and

a common electrode layer including the common electrode facing the liquid crystal.

9. The active matrix display according to claim 1, wherein the rear panel for cooperating with the front panel with sense electrodes, comprises:

an active matrix array of pixels;

a plurality of first sense circuits and second sense circuits; and

a plurality of coupling electrodes connected to respective x-sense circuits and y-sense circuits for capacitively coupling with coupling electrodes on the front panel for coupling capacitance sense signals from the sense electrodes to the sense circuits on the rear panel.

10. A method of sensing the position of a sensed object with an active matrix liquid crystal display with a transparent front substrate with a common electrode, a plurality of first sense electrodes extending across the display in a first x direction, and a plurality of second sense electrodes extending across the display in a second y direction across the row sense electrodes and an active rear substrate with an array of display pixels and a plurality of row sense circuits and column sense circuits, the method comprising:

driving the common electrode with a drive signal;

capacitatively coupling the drive signal on the first sense electrodes and second sense electrodes to respective row sense circuits and column sense circuits and detecting the capacitatively coupled drive signal on the row sense circuits and column sense circuits; and

detecting the changes in the detected drive signal on particular row sense circuits and column sense circuits caused by the presence of a sensed object adjacent to respective row sense electrodes and column sense electrodes to locate the sensed object.

11. The method according to claim 10 further comprising driving the pixels with pixel drive signals to cooperate with the drive signal driving the common electrode to display an image on the display.