MULTI TOUCH FLAT DISPLAY MODULE

• US 20090128508A1
• Filed: 10/01/2008
• Published: 05/21/2009
• Est. Priority Date: 11/19/2007
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Yu, Byung Chun, Sohn, Min Ho, Choi, Jong Seong, Lee, Sang Rae, Bae, Sang Hyuck, Jang, Hyung Uk
• Granted Patent: US 8,830,208 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A display module including a touch panel configured to be touched so as to input information, a liquid crystal display panel disposed below the touch panel and configured to display the information to be touched on the touch panel, a plurality of emitting light units configured to emit infrared light formed in at least two sides of the touch panel, a plurality of image sensors disposed below the liquid crystal panel and configured to detect infrared rays redirected through the liquid crystal panel towards the image sensors based on a touching of the touch panel, and a controller configured to determine a portion of the touch panel that is touched based on signals received from the plurality of image sensors.

Claims

1. A display module, comprising:

a touch panel configured to be touched so as to input information;

a liquid crystal display panel disposed below the touch panel and configured to display the information to be touched on the touch panel;

a plurality of emitting light units configured to emit infrared light formed in at least two sides of the touch panel;

a plurality of image sensors disposed below the liquid crystal panel and configured to detect infrared rays redirected through the liquid crystal panel towards the image sensors based on a touching of the touch panel; and

a controller configured to determine a portion of the touch panel that is touched based on signals received from the plurality of image sensors.

2. The display module of claim 1, wherein the controller is further configured to determine multiple portions of the touch panel simultaneously touched based on the signals received from the plurality of image sensors.

3. The display module of claim 2, wherein the controller determines the multiple portions of the touch panel simultaneously touched by unifying images captured the image sensors into a single image, converting the single image into binary data, sampling the binary data to determine multiple touched spots, and determining coordinates of the multiple touched portions based on the sampled touched spots.

4. The display module of claim 1, wherein a height between the touch panel and the plurality of image sensors disposed below the liquid crystal panel is determined based on the following equation:

$c=0.25\times <br><br>\sqrt{a^2+b^2}\times <br><br>\tan \left(\frac{\mathrm{\pi <br><br>}-\mathrm{\theta <br><br>}}{2}\right)$

wherein “

a”

is a horizontal distance of the liquid crystal panel, “

b”

is a vertical distance of the liquid crystal, and “

θ

”

is a sensing angle of a corresponding image sensor of the plurality of image sensors.

5. The display module of claim 1, wherein the touch panel is configured to reflect the infrared light emitted by the plurality of emitting light units such that the emitted light are guided within the touch panel,

wherein the infrared rays emitted by the plurality of emitting light units are reflected towards the plurality of image sensors based on the touching of the touch panel.

6. The display module of claim 1, further comprising:

a transmissive plate disposed below the liquid crystal display and configured to support the liquid crystal display and the touch panel and to direct the infrared rays towards the image sensors with minimal loss.

7. The display module of claim 1, further comprising:

a backlight unit that includes a cover housing a plurality of light sources configured to emit light towards the touch panel,

wherein the plurality of image sensors are disposed within the backlight unit.

8. The display module of claim 7, wherein the backlight unit further includes a reflection plate positioned substantially parallel with a bottom of the cover, and a plurality of optical sheets disposed above the reflection plate.

9. The display module of claim 1, wherein a wavelength of the infrared rays emitted by the plurality of emitting light units is greater than 850 nm.

10. The display module of claim 1, wherein the plurality of image sensors include only four image sensors.

11. The display module of claim 1, further comprising:

a plurality of light sources configured to emit light towards the touch panel; and

an interception filter included with a corresponding image sensor and configured to block light emitted by the light sources.

12. A method of controlling a touch panel including a liquid crystal display panel disposed below the touch panel, the method comprising:

displaying information to be touched on the touch panel;

emitting infrared light formed in at least two sides of the touch panel;

detecting infrared rays redirected through the liquid crystal panel via image sensors disposed below the liquid crystal panel based on a touching of the touch panel; and

determining a portion of the touch panel that is touched based on signals received from the plurality of image sensors.

13. The method of claim 12, wherein the determining step determines comprises:

determining multiple portions of the touch panel simultaneously touched based on the signals received from the plurality of image sensors.

14. The method of claim 13, wherein the step of determining multiple portions of the touch panel simultaneously touched comprises:

unifying images captured the image sensors into a single image;

converting the single image into binary data;

sampling the binary data to determine multiple touched spots; and

determining coordinates of the multiple touched portions based on the sampled touched spots.

15. The method of claim 12, wherein a height between the touch panel and the image sensors disposed below the liquid crystal panel is set based on the following equation:

$c=0.25\times <br><br>\sqrt{a^2+b^2}\times <br><br>\tan \left(\frac{\mathrm{\pi <br><br>}-\mathrm{\theta <br><br>}}{2}\right)$

wherein “

a”

is a horizontal distance of the liquid crystal panel, “

b”

is a vertical distance of the liquid crystal, and “

0”

is a sensing angle of a corresponding image sensor of the plurality of image sensors.

16. The method of claim 12, wherein the image sources are disposed in a backlight unit housing a plurality of light sources configured to emit light towards the touch panel,

wherein the plurality of image sensors are disposed within the backlight unit.

17. The method of claim 12, wherein a wavelength of the infrared rays emitted by the plurality of emitting light units is greater than 850 nm.