Surface emitting light source and projection display device using the same

• US 7,530,708 B2
• Filed: 10/04/2005
• Issued: 05/12/2009
• Est. Priority Date: 10/04/2004
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Park, Chan Young
• Primary Examiner(s): Truong; Bao Q
• Application Number:
  US11/242,710
• Publication Number:
  US 20060072316A1
• Time in Patent Office: 1,316 Days
• Field of Search: 362/268, 362/555, 362/297, 362/230, 362/231, 362/237, 362/241, 362/243, 362/245, 362/247, 362/301, 362/341, 362/800
• US Class Current: 362/231
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A surface emitting light source and projection display device using the same are disclosed, by which a highly integrated and/or high-output surface emitting light source are provided in a manner that improves the structure of semiconductor light emitting units. The present invention includes a plurality of semiconductor light emitting units arranged on a single plane, the semiconductor light emitting units emitting lights of at least two different colors, wherein the emitted lights are made to proceed externally within a predetermined angle.

Claims

1. A surface emitting light source, comprising:

a plurality of semiconductor light emitting units arranged on a single plane, the semiconductor light emitting units emitting lights of at least two different colors wherein the emitted lights are made to proceed externally within a predetermined angle,

wherein each of the plurality of semiconductor light emitting units comprises;

a light emitting diode, the light emitting diode including;

a transparent substrate;

a P-type semiconductor layer stacked below the transparent substrate;

an active layer stacked below a portion of a cut-out surface of the P-type semiconductor layer to emit light;

an N-type semiconductor layer stacked below the active layer;

a positive electrode and a negative electrode connected to the P and N-type semiconductor layers, respectively; and

a reflecting layer, the reflecting layer stacked below the positive and negative electrodes, including an electric signal line connected to the positive and negative electrodes;

a reflecting mirror mounted on the reflecting layer of the light emitting diode, reflecting the light emitted from the light emitting diode within the predetermined angle.

2. The surface emitting light source of claim 1, wherein the lights of the at least two different colors are sequentially emitted from the plurality of semiconductor light emitting units.

3. The surface emitting light source of claim 1, wherein at least two of the lights of the at least two different colors are simultaneously emitted from the plurality of semiconductor light emitting units.

4. The surface emitting light source of claim 1, wherein the plurality of semiconductor light emitting units are arranged in a checker board form on the plane.

5. The surface emitting light source of claim 1, wherein each of the plurality of semiconductor light emitting units is configured to have a flat shape.

6. The surface emitting light source of claim 1, wherein the reflecting mirrors of each of the plurality of semiconductor light emitting units are connected to one another.

7. The surface emitting light source of claim 1, wherein the reflecting mirror is provided on the reflecting layer to enclose the corresponding semiconductor light emitting unit in a truncated cone form having a diameter decreasing toward the reflecting layer.

8. The surface emitting light source of claim 1, wherein the reflecting mirror is provided on the reflecting layer to enclose the corresponding semiconductor light emitting unit in a truncated cone form having a diameter increasing toward the reflecting layer.

9. The surface light emitting source of claim 2 or claim 3, wherein the plurality of the semiconductor light emitting units emits red, green and blue lights, respectively and wherein a color of the light proceeding externally from the surface emitting light source corresponds to one selected from the group consisting of red, green, blue, white, magenta, cyan and yellow.

10. A projection display device comprising:

a surface emitting light source having a plurality of semiconductor light emitting units arranged on a single plane, the semiconductor light emitting units emitting lights of at least two different colors wherein the emitted lights are made to proceed externally within a predetermined angle;

a light illumination unit for creating a uniform brightness distribution of the light proceeding externally from the surface emitting light source;

a color image generating unit modulating light applied from the light illumination unit to generate a color image; and

an optical projection unit for enlarging and projecting the color image generated from the color image generating unit,

wherein each of the plurality of semiconductor light emitting units comprises;

a light emitting diode including;

a transparent substrate;

a P-type semiconductor layer stacked below the transparent substrate;

an active layer stacked below a portion of a cut-out surface of the P-type semiconductor layer to emit light;

an N-type semiconductor layer stacked below the active layer;

a positive electrode and a negative electrode connected to the P and N-type semiconductor layers, respectively; and

a reflecting layer, wherein the reflecting layer includes electric lines that are connected to the positive and negative electrodes of the light emitting diode, and wherein the reflecting layer is stacked below the positive and negative electrodes; and

a reflecting mirror mounted on the reflecting layer of the light emitting diode, reflecting the light emitted from the light emitting diode within the predetermined angle.

11. The projection display device of claim 10, further comprising:

an image control unit for controlling the color image generating unit and for synchronizing the color image with a clock signal; and

a light control unit for controlling the surface emitting light source so that the light corresponding to an input image signal is synchronized with the clock signal.

12. The projection display device of claim 11, wherein the light control unit causes the surface emitting light source to emit light having one color selected from the group consisting of red, green, blue, white, magenta, cyan and yellow, and wherein the plurality of semiconductor light emitting units emits red, green and blue lights.

13. The projection display device of claim 10, the light illumination unit comprising:

a rod lens for creating a uniform brightness distribution of the light proceeding externally from the surface emitting light source; and

an illumination lens for collecting the light coming from the rod lens and for applying the light coming from the rod lens to the color image generating unit.

14. The projection display device of claim 13, the light illumination unit further comprising a diffraction lens for condensing and reducing a radiation angle of the lights proceeding externally from the surface emitting light source, and wherein the rod lens creates a uniform brightness distribution of the light coming from the diffraction lens.

15. The projection display device of claim 14, wherein the diffraction lens is provided in close proximity to the surface emitting light source.

16. The projection display device of claim 14, wherein the diffraction lens is provided in close proximity to the rod lens.

17. The projection display device of claim 10, the color image generating unit comprising:

a total internal reflection prism for totally reflecting the light applied from the light illumination unit; and

a digital micro-mirror device modulating the light reflected from the total internal reflection prism to generate the color image.