Flat Panel Display with Integral Touch Screen

• US 20130127780A1
• Filed: 01/16/2013
• Published: 05/23/2013
• Est. Priority Date: 11/05/2008
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Selker, Ted
• Granted Patent: US 8,994,688 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G09G 5/003 Details of a display terminal, the details relating to the control arrangement of the display terminal and to the interfaces thereto specific for a CRT G09G1/165; for a flat panel G09G3/2092

Abstract

There are disclosed display devices with integral touch screens and methods for operating display panels. A display panel may include a plurality of pixels, each pixel controlled by a corresponding one of a plurality of column electrodes and a corresponding one of a plurality of row electrodes. Each column electrode may be coupled to a respective column driver circuit and at least some of the column electrodes may be coupled to respective column sensing circuits adapted to sense capacitive coupling between the respective column electrodes and a probe adjacent to an external surface of the display panel. Each row electrode may be coupled to a respective row driver circuit and at least some of the row electrodes may be coupled to respective row sensing circuits adapted to sense capacitive coupling between the respective row electrodes and a probe adjacent to an external surface of the display panel.

Claims

1. A display device with an integral touch screen, comprising:

a display panel comprising a plurality of pixels, a plurality of column electrodes, and a plurality of row electrodes, each pixel controlled by a corresponding one of the plurality of column electrodes and a corresponding one of the plurality of row electrodes,

wherein all of the column electrodes are coupled to respective column driver circuits and at least some of the column electrodes are coupled to respective column sensing circuits, each column sensing circuit adapted to sense capacitive coupling between the respective column electrode and a probe adjacent to an external surface of the display panel, and

wherein all of the row electrodes are coupled to respective row driver circuits and at least some of the row electrodes are coupled to respective row sensing circuits, each row sensing circuit adapted to sense capacitive coupling between the respective row electrode and a probe adjacent to an external surface of the display panel.

2. The display device of claim 1, wherein the column sensing circuits and the row sensing circuits sense the capacitive coupling to the probe by detecting one of a current flow in the respective column and row electrodes and a voltage coupled to the respective column and row electrodes.

3. The display device of claim 2, wherein

the probe is grounded

the column sensing circuits and the row sensing circuits sense the capacitive coupling to the probe by detecting a current flow in the respective column and row electrodes.

4. The display device of claim 2, wherein

the probe is connected to an AC voltage source

the column sensing circuits and the row sensing circuits sense the capacitive coupling to the probe by detecting a coupled AC voltage in the respective column and row electrodes.

5. The display device of claim 4, wherein

the AC voltage source has predetermined frequency

the column sensing circuits and the row sensing circuits include filters selective for the predetermined frequency.

6. The display device of claim 4, wherein

the row driver and the column driver cyclically write image data to the display panel

the column sensing circuits and the row sensing circuits detect a coupled AC voltage during a sensing interval within at least some of the writing cycles.

7. The display device of claim 6, wherein

the row driver circuits and the column driver circuits are in a high impedance state during each sensing interval.

8. The display device of claim 1, wherein

the display panel is a liquid crystal display panel using in-plane switching.

9. The display device of claim 1, wherein

the display panel is a light emitting diode display panel.

10. A method of operating a display panel having a plurality of pixels, a plurality of column electrodes, and a plurality of row electrodes, each pixel controlled by a corresponding one of the plurality of column electrodes and a corresponding one of the plurality of row electrodes, the method comprising:

forming an image on the display panel by applying respective drive signals to the plurality of column electrodes and the plurality of row electrode; and

determining a location of a probe adjacent to an external surface of the display panel by sensing capacitive coupling between the probe and one or more of the column electrodes and one or more of the row electrodes.

11. The method of claim 10, wherein sensing capacitive coupling between the probe and one or more of the column electrodes and one or more of the row electrodes:

detecting a current flow in the one or more of the column electrodes and the one or more of the row electrodes.

12. The method of claim 11, wherein

the probe is grounded.

13. The method of claim 10, wherein sensing capacitive coupling between the probe and one or more of the column electrodes and one or more of the row electrodes:

detecting a voltage coupled from the probe to the one or more of the column electrodes and the one or more of the row electrodes.

14. The method of claim 13, wherein

the probe is connect to an AC voltage source.

15. The method of claim 14, wherein

the AC voltage source has predetermined frequency, and

detecting a voltage coupled from the probe to one or more of the column electrodes and one or more of the row electrodes includes filtering the voltages on the at least some of the column electrodes and at least some of the row electrodes using respective filters selective for the predetermined frequency.

16. The method of claim 13, wherein

forming an image on the display panel by applying respective drive signals to the plurality of column electrodes and the plurality of row electrode is performed cyclically, and

detecting a voltage coupled from the probe to the one or more of the column electrodes and one or more of the row electrodes is performed during a sensing interval within at least some of the image forming cycles.

17. The method of claim 10, wherein

the display panel is a liquid crystal display panel using in-plane switching.

18. The method of claim 10, wherein

the display panel is a light emitting diode display panel.