Backlight unit and display device having the same

• US 7,728,923 B2
• Filed: 09/05/2006
• Issued: 06/01/2010
• Est. Priority Date: 09/09/2005
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Su-gun, Kim, Jung-hyeon, Lee, Jun-young, Cho, Tae-hee, Seong, Ki-bum
• Primary Examiner(s): PENG, CHARLIE Y
• Application Number:
  US11/515,043
• Publication Number:
  US 20070058393A1
• Time in Patent Office: 1,365 Days
• Field of Search: 349/65, 362/26, 362/601, 362/613, 362/612, 362/616
• US Class Current: 349/65
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133609 including means for improving the color mixing, e.g. white

Abstract

A backlight unit and method of use are provided having a first light guide plate, a linear light source disposed along at least one side edge of the first light guide plate, a plurality of second light guide plates facing the first light guide plate, and a point light source disposed along at least one side edge of each second light guide plate. Accordingly, the present invention can provide a backlight unit using both a point light source and a linear light source at substantially the same time, and having superior color reproducibility and low power consumption.

Claims

1. A backlight unit, comprising:

a first light guide plate;

at least one linear light source disposed adjacent to the first light guide plate;

a plurality of second light guide plates facing the first light guide plate;

a point light source disposed adjacent to each second light guide plate; and

a point light source circuit board on which the point light source is seated,

wherein a light exiting surface of the first light guide plate is substantially perpendicular to the point source circuit board.

2. The backlight unit according to claim 1, wherein the first light guide plate comprises:

a light exiting surface;

a first light incident surface provided on an opposite side of the light exiting surface; and

a second incident surface facing the linear light source,

wherein the plurality of second light guide plates face the first incident surface.

3. The backlight unit according to claim 2, wherein the plurality of light exiting surfaces of the second light guide plates are substantially parallel with the first incident surface of the first light guide plate.

4. The backlight unit according to claim 3, wherein distance between each light exiting surface of the second light guide plates and the first light incident surface of the first light guide plate is uniform.

5. The backlight unit according to claim 4, wherein the light exiting surface of the second light guide plates and light incident surface of the second light guide plates are substantially flat.

6. The backlight unit according to claim 2, further comprising a reflecting plate disposed under the second light guide plate.

7. The backlight unit according to claim 1, wherein the first light guide plate comprises:

a light reflecting surface provided on an opposite side of the light exiting surface; and

a light incident surface facing the linear light source,

wherein the plurality of second light guide plates face the light exiting surface of the first light guide plate.

8. The backlight unit according to claim 7, wherein the plurality of light exiting surfaces of the second light guide plates are substantially parallel with the light exiting surface of the first light guide plate.

9. The backlight according to claim 8, wherein distance between each light exiting surface of the second light guide plates and the light exiting surface of the first light guide plate is uniform.

10. The backlight unit according to claim 7, further comprising a reflecting plate disposed under the first light guide plate.

11. The backlight unit according to claim 1, wherein the first light guide plate comprises a flat plate shape.

12. The backlight unit according to claim 1, wherein the first light guide plate comprises a wedge shape.

13. The backlight unit according to claim 1, wherein the linear light source comprises at least one of a cold cathode fluorescent lamp (CCFL) and an external electrode fluorescent lamp (EEFL).

14. The backlight unit according to claim 1, wherein the point light source comprises a light emitting diode.

15. A display device, comprising:

a display panel;

a first light guide plate disposed in back of the display panel;

a linear light source disposed adjacent to the first light guide plate;

a plurality of second light guide plates disposed in back of the first light guide plate;

a point light source disposed adjacent to each second light guide plate; and

a point light source circuit board on which the point light source is seated,

wherein a light exiting surface of the first light guide plate is substantially perpendicular to the point source circuit board.

16. The display device according to claim 15, wherein a light exiting surface of the second light guide plate is substantially parallel with a light exiting surface of the first light guide plate.

17. The display device according to claim 16, wherein uniform distance between each light exiting surface of the second light guide plates and the light exiting surface of the first light guide plate is uniform.

18. the display device according to claim 15, wherein:

the first light guide plate comprises a flat plate shape; and

the second light guide plate comprises a wedge shape.

19. The display device according to claim 15, wherein the point light source comprises a light emitting diode.

20. The display device according to claim 15, wherein the display panel comprises a liquid crystal display panel.