Display with infrared backlight source and multi-touch sensing function

• US 20080074401A1
• Filed: 07/31/2007
• Published: 03/27/2008
• Est. Priority Date: 09/26/2006
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Ahn, In Ho, Chung, In Jae, Bae, Sang Hyuck
• Granted Patent: US 8,350,827 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 1/1368 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 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A touch-sensing display screen includes an upper transparent substrate, a lower substrate opposite the upper substrate, and a backlight unit having an infrared light source configured to radiate infrared light through the upper substrate in a first direction. A transparent window is disposed in alignment with the infrared light source and between the upper and lower transparent substrates. A portion of the infrared light radiated in the first direction is reflected back through the upper substrate and through the transparent window in a second direction by an object touching a surface of the upper transparent substrate. A pixel thin-film transistor on the lower substrate is configured to activate a pixel electrode, and an infrared light-sensing thin-film transistor is configured to sense the infrared light received through the upper substrate in the second direction, and output an infrared light-sense signal in response thereto.

Claims

1. A touch-sensing display screen comprising:

an upper transparent substrate;

a lower substrate opposite the upper substrate;

a backlight unit having an infrared light source configured to radiate infrared light through the upper substrate in a first direction;

a transparent window disposed in alignment with the infrared light source and between the upper and lower transparent substrates;

a portion of the infrared light radiated in the first direction being reflected back through the upper substrate and through the transparent window in a second direction by an object touching a surface of the upper transparent substrate;

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

an infrared light-sensing thin-film transistor in the pixel area configured to sense the infrared light received through the upper substrate and the transparent window in the second direction, and output an infrared light-sense signal in response thereto.

2. The touch-sensing display screen of claim 1, wherein the backlight unit includes a red light source, a green light source and a blue light source.

3. The touch-sensing display screen of claim 1, further comprising a signal processing circuit in communication with the infrared light-sense signal configured to correlate the infrared 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 an infrared light-sensing thin-film transistor.

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

7. The touch-sensing display screen of claim 6, wherein the number of infrared light-sensing thin-film transistors is less than the number of pixel thin-film transistors.

8. The touch-sensing display screen of claim 4, further comprising a second thin-film transistor in communication with the infrared light-sensing transistor.

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

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

11. The touch-sensing display screen of claim 10, 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.

12. The touch-sensing display screen of claim 12, further comprising a matrix of pixel areas, each pixel area having a pixel thin-film transistor, and some of the pixel areas having an infrared 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 infrared light-sensing transistor.

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

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

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

a display panel including a transparent window which transmits an infrared light, which is reflected from an opaque material, and a plurality of infrared ray sensors which sense the infrared light, which is incident via the transparent window; and

a backlight unit radiating the infrared light to the display panel.

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

a first transparent substrate where the transparent window is formed;

a second transparent substrate where the infrared ray sensors are formed; and

a liquid crystal layer which is formed between the first transparent substrate and the second transparent substrate.

17. The display having a multi-touch sensing function according to claim 16, wherein the second transparent substrate includes:

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

a plurality of gate lines which are arranged to cross the data lines and to be sequentially supplied with a scanning pulse;

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

a pixel electrode formed at a pixel area, the 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 to supply the data voltage to the pixel electrode in response to the scanning pulse;

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

a plurality of second driving voltage supplying lines arranged 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 that charges based on an electric charge from the infrared ray 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 are connected to 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, and

wherein the infrared ray sensor is an infrared ray sensing thin film transistor driven by the high-level driving voltage and the low-level driving voltage to flow current by the infrared light.

18. The display having a multi-touch sensing function according to claim 17, wherein the infrared ray 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.

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

red, green, and blue color filters formed at the same layer as the transparent layer; and

a black matrix 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.

20. The display having a multi-touch sensing function according to claim 17, wherein the liquid crystal display further includes:

a plurality of data integrated circuits connected to the data lines to convert touch images generated by a physical contact on the display panel, the data integrated circuits configured to convert digital video data of a touch image into the data voltage;

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 driving timing of the integrated circuits and supply the digital video data of the touch image to the data integrated circuit; and

a system circuit board in communication with the digital board, and

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.

21. The display having a multi-touch sensing function according to claim 15, wherein the backlight unit includes:

a plurality of red light sources that generate a red light;

a plurality of green light sources that generate a green light;

a plurality of blue light sources that generate a blue light; and

a plurality of infrared light sources that generate the infrared light.

22. The display having a multi-touch sensing function according to claim 15, wherein the number of the infrared light sources is less than the number of the red light sources, the number of the green light sources, and the number of the blue light sources.

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

preparing a display panel having a transparent window that transmits an infrared light, which is reflected from an opaque material, and a plurality of infrared ray sensors which sense the infrared light, which is incident via the transparent window; and

irradiating the infrared light to the display panel from under the display panel.

24. The method of driving the liquid crystal display having a multi-touch sensing function according to claim 23, the method further including:

simultaneously sensing infrared light of each of the plurality of touch images, which are simultaneously touched on a display surface of the display panel, using the infrared ray sensors.