EDGE TYPE BACKLIGHT UNIT HAVING LOCAL DIMMING FUNCTION

• US 20100134405A1
• Filed: 11/09/2009
• Published: 06/03/2010
• Est. Priority Date: 11/28/2008
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Hahm, Hun Joo, PARK, Jung Kyu
• Application Number:
  US12/615,072
• Publication Number:
  US 20100134405A1
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/3522 the optical element enabling or impairing total internal reflection using evanescent coupling G02B6/3536
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines

Abstract

Disclosed is an edge type backlight unit having a local dimming function realized by adjusting the distance between a light guide plate and a plurality of optical systems disposed under the light guide plate. The edge type backlight unit includes a light guide plate guiding light emitted from a light source, and a luminance control unit including a plurality of optical systems reflecting light guided by the light guide plate and emitting the light to a liquid crystal panel, and controlling luminance by controlling the reflectance of each of the plurality of optical systems according to an input image signal.

Claims

1. An edge type backlight unit having a local dimming function comprising:

a light guide plate guiding light emitted from a light source; and

a luminance control unit including a plurality of optical systems reflecting light guided by the light guide plate and emitting the light to a liquid crystal panel, the luminance control unit controlling luminance by controlling the reflectance of each of the plurality of optical systems according to an input image signal.

2. The edge type backlight unit of claim 1, wherein the luminance control unit further comprises a controller supplying control voltages, each having a voltage level varied according to the contrast of the image signal, to the plurality of optical systems, respectively.

3. The edge type backlight unit of claim 2, wherein the optical systems each have a variable distance from the light guide plate, the distance being controlled by piezoelectric effects.

4. The edge type backlight unit of claim 2, wherein the luminance control unit further comprises a plurality of first electrodes disposed under the light guide plate in one-to-one correspondence with the plurality of optical systems,

wherein the controller applies the control voltages to the first electrodes and the optical systems, respectively, and

the optical systems each have a variable distance from the light guide plate, the distance being controlled by an electrostatic force with the first electrode.

5. The edge type backlight unit of claim 4, wherein the luminance control unit further comprises a plurality of second electrodes disposed under the light guide plate in one-to-one correspondence with the plurality of optical systems,

wherein the controller applies the control voltages to the first electrodes, the optical systems and the second electrodes respectively, and

the optical systems are disposed between the first electrodes and the second electrodes, and each have a variable distance from the light guide plate, the distance being controlled by an electrostatic force with the first and second electrodes.

6. The edge type backlight unit of claim 2, wherein the luminance control unit further comprises a spacer spacing the optical system from the light guide plate at a preset distance.

7. The edge type backlight unit of claim 1, wherein the optical system is one of a reflection plate reflecting light, a scattering pattern scattering light, and a diffusion sheet diffusing light.

8. The edge type backlight unit of claim 7, wherein the optical system includes a coating layer increasing light reflectance, on a surface thereof.

9. The edge type backlight unit of claim 4, wherein the first electrode is formed of a transparent material.

10. The edge type backlight unit of claim 5, wherein the first electrode or the second electrode is formed of a transparent material.

11. The edge type backlight unit of claim 1, further comprising an optical member directing light, emitted from the light source to the light guide plate, to a preset direction.

12. The edge type backlight unit of claim 1, wherein the light source controls the quantity of incident light in association with the luminance control of the luminance control unit.

13. The edge type backlight unit of claim 4, wherein the luminance control unit further comprises a spacer spacing the optical system from the light guide plate at a preset distance.

14. The edge type backlight unit of claim 5, wherein the luminance control unit further comprises a spacer spacing the optical system from the light guide plate at a preset distance.