Display having infrared edge illumination and multi-touch sensing function

• US 20080252618A1
• Filed: 09/26/2007
• Published: 10/16/2008
• Est. Priority Date: 09/26/2006
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Chung, In Jae, Baik, Seong Ho, Ahn, In Ho, Bae, Sang Hyuck
• Granted Patent: US 8,102,378 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2203/11 involving infrared radiation
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

A touch-sensing display screen includes an upper transparent substrate, a lower substrate opposite the upper substrate and an infrared light source configured to illuminate a portion of the upper transparent substrate. A light converting layer is disposed between the upper and lower substrate and is configured to convert the infrared light received by the upper transparent substrate to visible light. A pixel thin-film transistor on the lower substrate is configured to activate a pixel electrode, and a light-sensing thin-film transistor is configured to sense the visible light provided by the light converting layer. A light-sense signal is output in response to activation of the light-sensing thin-film transistor.

Claims

1. A touch-sensing display screen comprising:

an upper transparent substrate;

a lower substrate opposite the upper substrate;

an infrared light source configured to illuminate a portion of the upper transparent substrate;

a light converting layer disposed between the upper and lower substrates configured to convert the infrared light received by the upper transparent substrate to visible light;

a pixel area on the lower substrate having a thin-film transistor configured to activate a pixel electrode; and

a light-sensing thin-film transistor in the pixel area configured to sense the visible light provided by the light converting layer and output a light-sense signal in response thereto.

2. The touch-sensing display screen of claim 1, wherein

the upper transparent substrate is configured to prevent the infrared light from reaching the light converting layer if no object contacts a surface of the upper transparent substrate;

and

wherein the upper transparent substrate is configured to direct a portion of the infrared light to the light converting layer when an object contacts the surface of the upper transparent substrate causing the infrared light to scatter.

3. The touch-sensing display screen of claim 2, further comprising a signal processing circuit in communication with the light-sense signal configured to correlate the light-sense signal with one or more locations on the surface of the upper transparent substrate contacted by the object.

4. The touch-sensing display screen of claim 1, further comprising a matrix of pixel areas each having a pixel thin-film transistor configured to activate a corresponding pixel electrode.

5. The touch-sensing display screen of claim 4, wherein each pixel area further comprises a light-sensing thin-film transistor.

6. The touch-sensing display screen of claim 4, wherein some of the pixels areas include a light-sensing thin film transistor.

7. The touch-sensing display screen of claim 1, further comprising a second thin-film transistor in communication with the light-sensing transistor.

8. The touch-sensing display screen of claim 7, wherein the second thin-film transistor facilitates outputting the light-sense signal.

9. The touch-sensing display screen of claim 8, further comprising a gate line connected to the respective pixel thin-film transistor and to the respective light-sensing transistor to facilitate identification of pixel locations where the light-sensing transistors received the visible light.

10. The touch-sensing display screen of claim 8, further comprising a data line connected to the respective pixel thin-film transistor, wherein activation of both the data line and the gate line activates the corresponding pixel electrode.

11. The touch-sensing display screen of claim 10, further comprising a matrix of pixel areas, each pixel area having a pixel thin-film transistor, and some of the pixel areas having a light-sensing thin-film transistor, wherein identification of the gate and data lines that activate a selected pixel thin-film transistor facilitates identification of a corresponding active light-sensing transistor.

12. The touch-sensing display screen of claim 11, further comprising an image processing circuit configured analyze locations of a plurality of active light-sensing transistors based on the gate and data lines of corresponding pixel thin-film transistors to detect one or more centers of touch.

13. The touch-sensing display screen of claim 12, wherein the image processing circuit is configured to identify a boundary associated with the centers of touch.

14. The touch-sensing display screen of claim 1, wherein the infrared light source illuminates the upper transparent substrate along one or more edges thereof.

15. A display having a multi-touch sensing function, comprising:

an infrared light source that radiates an infrared light; and

a display panel that includes a first transparent substrate which guides the infrared light, an infrared ray-to-visible ray converting layer formed on the first transparent substrate to convert the infrared light from the first transparent substrate into a visible ray, and an optical sensor located under the first transparent substrate to sense the visible ray.

16. The display having a multi-touch sensing function according to claim 15, further comprising:

a backlight unit located under the display panel to radiate a light to the display panel.

17. The display having a multi-touch sensing function according to claim 15, wherein the display panel includes:

a second transparent substrate on which the optical sensor is formed; and

a liquid crystal layer formed between the transparent substrates.

18. The display having a multi-touch sensing function according to claim 17, wherein the second transparent substrate includes:

a plurality of data lines to which a data voltage is supplied;

a plurality of gate lines crossed with the data lines, and sequentially supplied with a scanning pulse;

a plurality of read-out lines parallel to the data lines configured to output an infrared ray sensing signal corresponding to infrared light reflected from the first transparent substrate;

a pixel electrode formed at a pixel area defined by the data line, the gate line, and the read-out line;

a plurality of first thin film transistors formed at a crossing part of the gate lines configured to supply the data voltage to the pixel electrode in response to the scanning pulse;

a plurality of first driving voltage supplying lines parallel to the gate lines to supply a high-level driving voltage to the optical sensor;

a plurality of second driving voltage supplying lines parallel to the gate lines and the first driving voltage lines, to supply a low-level driving voltage to the infrared ray sensor;

a first storage capacitor charging an electric charge from the optical sensor;

a second storage capacitor formed between the pixel electrode and the gate line to maintain a voltage of the pixel electrode; and

a plurality of second thin film transistors formed at a crossing part of the gate lines and the read-out lines, and in communication with the first storage capacitor to supply an electric charge from a first storage capacitor to the read-out lines in response to the scanning pulse.

19. The display having a multi-touch sensing function according to claim 18, wherein the optical sensor includes:

a thin film transistor driven by the high-level driving voltage and the low-level driving voltage to cause current flow between its source electrode and drain electrode.

20. The display having a multi-touch sensing function according to claim 19, wherein the optical sensor includes:

a gate electrode integrally formed with the second driving voltage supplying line;

a semiconductor layer overlapping the gate electrode with an insulating film therebetween;

a source electrode connected to the first driving voltage supplying line on the semiconductor layer; and

a drain electrode opposite the source electrode on the semiconductor layer.

21. The display having a multi-touch sensing function according to claim 18, wherein the first transparent substrate further includes:

red, green, and blue color filters formed at the same layer as the infrared ray-to-visible ray converting layer; and

a black matrix that is formed at a border between the pixel areas and at an area corresponding to the first and second thin film transistors to shield an infrared light which is incident into the first and second thin film transistors.

22. The display having a multi-touch sensing function according to claim 18, further includes:

a plurality of data integrated circuits connected to the data lines to convert a digital video data of touch images generated by a physical touch contacting the display panel, into the data voltage to be supplied to the data lines;

a plurality of gate integrated circuits connected to the gate lines to sequentially supply the scanning pulse to the gate lines;

a read-out integrated circuit connected to the read-out lines to amplify an electric charge from the read-out lines, thereby outputting an amplified voltage;

a digital board configured to control the integrated circuits and the digital video data of the touch image; and

a system circuit board connected to the digital board.

23. The display having a multi-touch sensing function according to claim 22, wherein the digital board or the system circuit board includes a digital touch image processing circuit configured to analyze a pattern of the touch images to detect a center of touch images.

24. A method of driving a display having a multi-touch sensing function comprising:

irradiating a first transparent substrate with an infrared light;

converting the infrared light reflected from a surface of the first transparent substrate into a visible ray using an infrared ray-to-visible ray converting layer formed on the first transparent substrate; and

sensing the visible ray using an optical sensor located under the first transparent substrate.

25. The method of driving the display having a multi-touch sensing function according to claim 24, further includes:

irradiating a display panel with light generated by a backlight unit located under the display panel; and

displaying a touch image of the surface of the first transparent substrate on the display panel.