Flat panel display screen operable for touch position determination system and methods

• US 20070216657A1
• Filed: 03/17/2006
• Published: 09/20/2007
• Est. Priority Date: 03/17/2006
• Status: Active Grant

• Current Assignee: Jeffrey Konicek
• Original Assignee: Jeffrey Konicek
• Inventors: Konicek, Jeffrey
• Granted Patent: US 8,144,115 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0444 using a single conductive element covering the whole sensing surface, e.g. by sensing the electrical current flowing at the corners
• CPC Class Codes: G06V 40/12 Fingerprints or palmprints

Abstract

A system and method are disclosed that determines the location of an object touching a display screen. The system and method modifies already existing display technology, including using the underlying structure of many types of existing displays as the touch detecting structure. The systems and methods are applicable to virtually all LCD and LCD-like displays, including emissive displays (OLED, PLED, quantum dot displays, etc.), electronic paper, and others.

Claims

1. A method of determining the approximate location of contact on a display, the display having a display surface and plurality of pixels at defined pixel locations, each pixel location including a pixel plate capacitor, comprising:

i) applying a voltage to the pixel plate capacitors of the display, the applied voltage having an AC component and the pixel plate capacitors exhibiting a detectable capacitance;

ii) causing the detectable pixel plate capacitance to increase by contacting the display surface with an object;

iii) monitoring an aspect of the applied AC component of the voltage at the pixel plate capacitors to electrically observe the increase in pixel plate capacitance;

iv) comparing the monitored pixel plate capacitance of each pixel plate capacitor to a predetermined value; and

v) identifying the approximate location in the display of the pixel having a pixel plate capacitance above the predetermined value.

2. The method of claim 1 wherein the aspect of the applied AC component comprises the phase of the AC component.

3. The method of claim 1 wherein the aspect of the applied AC component comprises the magnitude of the current of the AC component.

4. The method of claim 1 wherein the display is an LCD display.

5. The method of claim 1 wherein the display is an OLED display.

6. The method of claim 1 wherein the display comprises a linear display.

7. The method of claim 1 wherein the display comprises a two-dimensional display.

8. The method of claim 1 wherein each pixel location of the display also includes a storage capacitor selectively coupled to the pixel plate capacitor, and the operation of monitoring the applied AC component of the voltage at the pixel plate capacitor includes decoupling the storage capacitor from the pixel plate capacitor.

9. The method of claim 8 wherein the storage capacitor is a stabilizing capacitor, and wherein the operation of decoupling the stabilizing capacitor includes operating a switching device coupled between the stabilizing capacitor and [insert].

10. The method of claim 1 wherein the pixels include a pixel conductor plate coupled to a stabilizing capacitor, and further comprising selectively decoupling the stabilizing capacitor from the pixel conductor plate.

11. A method of determining the approximate location of contact on a display having a plurality of pixel locations and a plurality of associated pixel capacitors, comprising:

i) applying a voltage to a first pixel capacitor of the display, the applied voltage having a AC component;

ii) electrically observing an aspect of the applied AC component at a second pixel location;

iii) comparing the observed aspect of the applied AC component at the second pixel location to a predetermined value; and

iv) indicating that there is an object in contact with the surface of the display at the first or second pixel location when the observed aspect of the applied AC component is above the predetermined value.

12. An emissive display apparatus having a plurality of pixel locations, said pixel locations comprising two electrodes surrounding an electrically operable optically emissive material layer, wherein one of said plates is common among at least some of the pixels and the other of said plates is selectively coupled to an observing circuit, the observing circuit configured to electrically observe an aspect of an AC signal that is applied to a pixel other than that being observed.

13. A method of determining the location of touch contact with a display panel, the display panel including a plurality of pixels and a common electrode forming an electrical element of the plurality of pixels and wherein the common electrode has a frequency-dependent impedance comprising:

i) applying a plurality of AC signals laterally across the common electrode of the display panel;

ii) determining the AC current flow caused by the AC signals applied to the common electrode;

iii) detecting a variation in any of the AC currents in the common electrode caused by an external object in contact with the display panel; and

iv) determining the approximate location on the display panel of the object in contact with the display panel by observing the ratios of the AC currents flowing into the display panel.