Liquid crystal display to which infrared rays source is applied and multi-touch system using the same

• US 8,624,810 B2
• Filed: 12/23/2008
• Issued: 01/07/2014
• Est. Priority Date: 12/31/2007
• Status: Expired due to Fees

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Lim, Dae-San, Choi, Jong-Seong, Jang, Hyung-Uk, Bae, Sang-Hyuck, Yu, Byung-Chun, Ahn, In-Ho, Lee, Sang-Rae
• Primary Examiner(s): Giesy, Adam R
• Assistant Examiner(s): HEYI, HENOK G
• Application Number:
  US12/343,131
• Publication Number:
  US 20090167656A1
• Time in Patent Office: 1,841 Days
• Field of Search: None
• US Class Current: 345/87
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

There are provided a liquid crystal display (LCD) to which infrared rays (IR) light sources are applied and a multi-touch system using the same. The LCD to which IR light sources are applied includes a back light in which a plurality of lamp light sources and a plurality of IR light sources are repeatedly arranged in column and row directions, a diffusion plate and a plurality of optical sheets arranged on the back light, and an LCD panel provided on the back light to display an image using light incident from the back light.

Claims

1. A multi-touch system to which an LCD is applied, comprising:

the LCD including a back light in which a plurality of lamp light sources and a plurality of IR light sources are repeatedly arranged in column and row directions, an LCD panel provided on the back light to display an image using light incident from the back light, and a touch panel attached onto the LCD panel;

a plurality of cameras that are provided at upper edges of the LCD and in which IR light incident from the IR light sources provided in the LCD is reflected by a touch object and the reflected IR light is incident to create a touch sense image; and

an IR light transmission filter provided at the front of each of the cameras, wherein the IR light transmission filter provides only the IR light transmitted from the IR light sources into the cameras,

wherein the lamp light source is selected from a light emitting diode (LED), electroluminescence (EL), a cold cathode fluorescent lamp (CCFL), and an external electrode fluorescent lamp (EEFL), and

wherein the LCD senses touch using a principle in which the image incident on the camera varies, the IR light transmitted from the IR light sources of the back light to the surface of the LCD is reflected by the touch object to be incident into the camera through the IR light transmission filter, and only a touch surface region by the touch object is extracted from an entire image so that the touch surface region undergoes a signal processing process and a clear touch sense image is created.

2. The multi-touch system as claimed in claim 1, wherein, when the CCFL or the EEFL is used as the lamp light source, the plurality of IR light sources are repeatedly arranged together with one CCFL or EEFL.

3. The multi-touch system as claimed in claim 1, wherein, when the LED light source is used as the lamp light source, one LED and one IR light source are repeatedly and alternately arranged in column and row directions.

4. The multi-touch system as claimed in claim 1, wherein the LED light sources are repeatedly arranged in column and row directions in units of three R, G, and B LEDs and one IR light source.

5. The multi-touch system as claimed in claim 1, wherein an IR light transmission filter is provided in the LCD panel.