Multi touch flat display module

• US 8,830,208 B2
• Filed: 10/01/2008
• Issued: 09/09/2014
• Est. Priority Date: 11/19/2007
• Status: Expired due to Fees

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Sohn, Min Ho, Choi, Jong Seong, Jang, Hyung Uk, Lee, Sang Rae, Bae, Sang Hyuck, Yu, Byung Chun
• Primary Examiner(s): Lefkowitz, Sumati
• Assistant Examiner(s): SOTO LOPEZ, JOSE R
• Application Number:
  US12/243,750
• Publication Number:
  US 20090128508A1
• Time in Patent Office: 2,169 Days
• Field of Search: 345/173, 345/175
• US Class Current: 345/175
• 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 infrared 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 display panel and configured to detect infrared rays redirected through the liquid crystal display panel towards the image sensors based on a touching of the touch panel;

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

a transparent transmissive plate supporting the liquid crystal display panel at an upper part of a side frame;

an outer frame formed along an outer circumference of the touch panel to fix the plurality of infrared emitting light units;

a spacer maintaining a gap for the liquid crystal display panel between a light guide panel and the transparent transmissive plate, said light guide panel configured to guide infrared light emitted by the plurality of infrared emitting light units; and

a backlight unit including a cover, a circuit board, a flat reflection plate, and a plurality of flat optical sheets, the cover housing a plurality of visible light sources connected to the circuit board, the plurality of visible light sources being configured to emit visible light towards the touch panel, the flat reflection plate being positioned above the circuit board so as to not be in contact with the circuit board, the plurality of flat optical sheets being positioned above the flat reflection plate so as to not be in contact with the flat reflection plate,

wherein a surface of the flat reflection plate and a surface of each the plurality of flat optical sheets are in parallel to a surface of the circuit board,

wherein each of the plurality of image sensors and the plurality of visible light sources are directly connected to the circuit board, each of the plurality of visible light sources extend through the flat reflection plate to emit light through the flat reflection plate and the plurality of flat optical sheets, and each of the plurality of image sensors extend through the flat reflection plate to detect infrared rays emitted by the plurality of infrared emitting light units,

wherein the transparent transmissive plate is configured such that the redirected infrared rays are all transmitted substantially without loss,

wherein corresponding infrared emitting light units included in the plurality of infrared emitting light units disposed in the at least two sides of the touch panel face each other and have a same cross-sectional center axis,

wherein the plurality of infrared emitting light units emit infrared rays from one long side and one short side of the outer frame to the inside of the light guide panel so as to enable detection of spots touched,

wherein the transmittance of the liquid crystal display panel is a wavelength of visible light of 460 nm˜

700 nm, and the infrared rays of the plurality of infrared emitting light units have a wavelength greater than 850 nm,

wherein the plurality of image sensors are configured to detect the infrared rays having a wavelength transmitted through the liquid crystal display panel of greater than 20% of the wavelength of the visible light transmitted through the liquid crystal display panel,

wherein a height between the touch panel and the plurality of image sensors extended through the flat reflection plate is determined based on the equation;

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 the touch panel is configured to reflect the infrared light emitted by the plurality of infrared emitting light units such that the emitted infrared light are guided within the touch panel, and

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

5. The display module of claim 1, wherein the transmissive plate is 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.

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

wherein the image sensors are symmetrically disposed with respect to the liquid crystal panel and the plurality of visible light sources.

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

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

8. The display module of claim 7, wherein the visible light sources are disposed on a same plane as the image sensors, and the visible light sources and the image sensor are disposed below the facing infrared emitting light units such that infrared light reflected by multiple touches on the touch panel reflects towards the visible light sources and the image sensors and visible light from the visible light sources projects upward toward the liquid crystal panel.

9. 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 via a plurality of infrared emitting light units;

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

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

supporting the liquid crystal display panel at an upper part of a side frame using a transparent transmissive plate;

providing a backlight unit including a cover, a circuit board, a flat reflection plate, and a plurality of flat optical sheets, the cover housing a plurality of light sources connected to the circuit board, the plurality of light sources being configured to emit light towards the touch panel, the flat reflection plate being positioned above the circuit board so as to not be in contact with the circuit board, the plurality of flat optical sheets being positioned above the flat reflection plate so as to not be in contact with the flat reflection plate,

wherein a surface of the flat reflection plate and a surface of each the plurality of flat optical sheets are in parallel to a surface of the circuit board, and

wherein each of the plurality of image sensors and the plurality of light sources are directly connected to the circuit board, each of the plurality of light sources extend through the flat reflection plate to emit light through the flat reflection plate and the plurality of flat optical sheets, and each of the plurality of image sensors extend through the flat reflection plate to detect infrared rays emitted by the plurality of infrared emitting light units; and

maintaining a gap for the liquid crystal display panel between a light guide panel and the transparent transmissive plate using a spacer, said light guide panel guiding infrared light emitted by the infrared emitting light units,

wherein the transparent transmissive plate is configured such that the redirected infrared rays are all transmitted substantially without loss,

wherein corresponding infrared emitting light units included in the plurality of infrared emitting light units disposed in the at least two sides of the touch panel face each other and have a same cross-sectional center axis,

wherein the plurality of infrared emitting light units emit infrared rays from one long side and one short side of a outer frame to the inside of the light guide panel so as to enable detection of spots touched,

wherein the outer frame is formed along an outer circumference of the touch panel to fix the plurality of infrared emitting light units,

wherein the transmittance of the liquid crystal display panel is a wavelength of visible light of 460 nm˜

700 nm, and the infrared rays of the plurality of infrared emitting light units have a wavelength greater than 850 nm,

wherein the plurality of image sensors are configured to detect the infrared rays having a wavelength transmitted through the liquid crystal display panel of greater than 20% of the wavelength of the visible light transmitted through the liquid crystal display panel,

wherein a height between the touch panel and the plurality of image sensors extended through the flat reflection plate is determined based on the equation;

10. The method of claim 9, wherein the determining step comprises:

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

11. The method of claim 10, 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.

12. The method of claim 9, wherein the visible light sources are disposed on a same plane as the image sensors, and the visible light sources and the image sensors are disposed below the facing infrared emitting light units such that infrared light reflected by multiple touches on the touch panel reflects towards the visible light sources and the image sensors and visible light from the visible light sources projects upward toward the liquid crystal panel.