Light Emitting Device, Manufacturing Method For Light Emitting Device, Illumination Device Using Light Emitting Device, And Projector

• US 20080030691A1
• Filed: 04/18/2005
• Published: 02/07/2008
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Olympus Corporation
• Original Assignee: Olympus Corporation
• Inventors: Godo, Hirokazu
• Granted Patent: US 7,918,567 B2
• Time in Patent Office: Days
• US Class Current: 353/98
• CPC Class Codes: G02B 27/09 Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements
• 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

Abstract

A light emitting device capable of achieving a small exit area, high directivity, and low loss; a manufacturing method thereof; an illumination device using this light emitting device; and a projector are provided. The light emitting devices 16 include an LED (light emitting element) 25, in the form of a rectangular light emitting element, having a light emitting part 23 for emitting illumination light; a substrate 26 for fixing the LED 25; a spacer 27 having a mirror surface 27A for reflecting the illumination light emitted from the LED 25; and a tapered rod (columnar light guide unit) 28 having a device-side incident surface (incident surface) 28A upon which illumination light is incident, tapered-rod side surfaces 28B serving as total reflection surfaces for totally reflecting illumination light received from the device-side incident surface 28A, and the device-side exit surface (exit surface) 28C which has a larger area than the device-side incident surface 28A and which emits the illumination light totally reflected at the tapered-rod side surfaces 38B.

Claims

1. A light emitting device comprising:

at least one light emitting element having a light emitting part for emitting illumination light;

a substrate to which the light emitting element is fixed;

a spacer having a mirror surface for reflecting the illumination light emitted from the light emitting element; and

at least one columnar light guide unit having an incident surface upon which the illumination light is incident, a total reflection surface for totally reflecting the illumination light coming from the incident surface, and an exit surface having an area larger than that of the incident surface, the exit surface emitting the illumination light totally reflected at the total reflection surface, wherein

the spacer includes an indentation open at least at a top thereof or an opening,

the light emitting element is positioned with respect to a bottom surface of the indentation or the opening and a bottom surface of the spacer,

the mirror surface is formed on the indentation or an inner side surface of the opening,

the area of the opening at the top surface of the spacer is larger than a bottom surface area of the indentation or the area of the opening at the bottom surface of the spacer, and

the incident surface of the at least one columnar light guide unit is located in the indentation or on the spacer top surface at the opening, the indentation or the opening is filled with a transparent member, at least the light emitting unit of the light emitting element is shielded from the air by the transparent member, and no air space exists between the incident surface and the transparent member.

3. The light emitting device according to claim 1, wherein the incident surface of the at least one columnar light guide unit and the spacer top surface are located substantially at an identical position.

4. The light emitting device according to claim 1, wherein the incident surface of the at least one columnar light guide unit is disposed in the indentation or the opening, an edge of the incident surface being in contact with the mirror surface.

5. The light emitting device according to claim 1, wherein

the refractive index of the transparent member is smaller than that of the columnar light guide unit.

6. The light emitting device according to claim 1, wherein the light emitting element is connected to the substrate with a bonding wire, and

a distance from the bottom surface of the indentation or the bottom surface of the spacer to the incident surface of the columnar light guide unit is substantially equal to a distance from the top surface of the substrate to a most distant position of the bonding wire.

7. The light emitting device according to claim 1, wherein

an electrode is disposed on a face of the light emitting element, the face being opposite the substrate;

the electrode is connected directly to the substrate; and

a distance from the bottom surface of the indentation or the bottom surface of the spacer to the incident surface of the columnar light guide unit is substantially equal to a distance from the top surface of the substrate to the top surface of the light emitting element.

8. The light emitting device according to claim 1, wherein

an electrode is disposed on the spacer,

the light emitting element is connected directly to the substrate via the electrode, and

a distance from the bottom surface of the indentation or the bottom surface of the spacer to the incident surface of the columnar light guide unit is larger than a distance from the top surface of the substrate to the electrode.

9. The light emitting device according to claim 1, wherein the condition n1>

n2≧

m1>

m2 is satisfied, where

m1 represents the area of the opening on the top surface of the spacer at the indentation or the opening,

m2 represents the bottom surface area of the indentation or the area of the opening at the bottom surface of the spacer,

n1 represents an area of the exit surface of the columnar light guide unit, and

n2 represents an area of the incident surface of the columnar light guide unit.

10. The light emitting device according to claim 1, wherein the condition n1>

m1>

n2>

m2 is satisfied, where

m1 represents the area of the opening on the top surface of the spacer at the indentation or the opening,

m2 represents the bottom surface area of the indentation or the area of the opening at the bottom surface of the spacer,

n1 represents an area of the exit surface of the columnar light guide unit, and

n2 represents an area of the incident surface of the columnar light guide unit.

11. The light emitting device according to claim 9, wherein

an inside dimension of the indentation or the opening enclosed by the mirror surface along a direction of the spacer top surface becomes gradually larger from the spacer bottom surface towards the spacer top surface, and

an inside dimension of the columnar light guide unit enclosed by the total reflection surface along a direction of the incident surface becomes gradually larger from the incident surface towards the exit surface.

12. The light emitting device according to claim 1, wherein said light emitting element includes two light emitting elements,

one end of a bonding wire is connected to each of the two light emitting elements, and the other end of the bonding wire is connected to one pad provided on the substrate.

13. The light emitting device according to claim 12, wherein the pad is provided between the two light emitting elements.

14. The light emitting device according to claim 12, wherein said columnar light guide unit includes two columnar light guide units corresponding to the light emitting elements, respectively.

15. The light emitting device according to claim 12, wherein said columnar light guide unit includes one columnar light guide unit corresponding to the two light emitting elements.

16. The light emitting device according to claim 1, further comprising a rod holding unit formed integrally with the spacer to support the at least one columnar light guide unit.

17. The light emitting device according to claim 16, wherein the rod holding unit maintains a constant distance between the exit surface of the at least one columnar light guide unit and the spacer top surface.

18. The light emitting device according to claim 17, wherein the rod holding unit supports the at least one columnar light guide unit by the exit surface.

19. The light emitting device according to claim 16, wherein the rod holding unit includes a heat radiator for dissipating heat generated by the light emitting element.

20. An illumination device comprising a plurality of the light emitting devices according to claim 1, wherein

the light emitting devices are disposed around a circle having a center thereof in an intersecting area of a certain size such that normals to the exit surfaces of the columnar light guide units intersect in the intersecting area.

21. An illumination device comprising a plurality of the light emitting devices according to claim 1, wherein

the light emitting devices are disposed around a circle having a center thereof in an intersecting area of a certain size such that normals to the exit surfaces of the columnar light guide units intersect in the intersecting area, the exit surfaces being adjacent to one another, and

the two light emitting elements are disposed side by side in a direction perpendicular to the circumference.

22. The illumination device according to claim 20, comprising:

a light-emitting-device control unit for time-sequentially illuminating the light emitting elements for each light emitting device; and

a light-collecting unit for collecting the illumination light from each of the light emitting devices to illuminate an illumination area, wherein

the light-emitting-device control unit controls a variation in the amount of illumination light in the illuminated area to within a certain range.

23. The illumination device according to claim 21, comprising:

a light-emitting-device control unit for time-sequentially illuminating the light emitting elements for each light emitting device; and

a light-collecting unit for collecting the illumination light from each of the light emitting devices to illuminate an illumination area, wherein

the light-emitting-device control unit controls a variation in the amount of illumination light in the illuminated area to within a certain range.

24. A projector including the illumination device according to claim 20 for emitting illumination light according to input image information, comprising:

a spatial modulating element for modulating illumination light emitted by the illumination device according to input image information; and

a projection optical unit for projecting the illumination light modulated by the spatial modulating element onto a screen.

25. A projector including the illumination device according to claim 21 for emitting illumination light according to input image information, comprising:

a spatial modulating element for modulating illumination light emitted by the illumination device according to input image information; and

a projection optical unit for projecting the illumination light modulated by the spatial modulating element onto a screen.

26. A manufacturing method for the light emitting device according to claim 1, comprising:

a first step of positioning the bottom surface of the indentation of the spacer or the bottom surface of the spacer with respect to the substrate;

a second step of positioning the incident surface of the at least one columnar light guide unit with respect to an open area of the spacer top surface; and

a third step of filling the indentation enclosed by the incident surface or the opening enclosed by the substrate and the incident surface with a transparent member having a refractive index smaller than that of the columnar light guide unit such that no air space remains on the incident surface and the transparent member does not adhere to a side face functioning as the total reflection surface of the columnar light guide unit.

27. A manufacturing method for the light emitting device according to claim 1, comprising:

a first step of positioning the bottom surface of the indentation of the spacer or the bottom surface of the spacer with respect to the substrate;

a second step of filling the indentation or the opening having a bottom surface thereof enclosed by the substrate with a transparent member having a refractive index smaller than that of the columnar light guide unit; and

a third step of moving the incident surface of the at least one columnar light guide unit to an open area of the spacer top surface for positioning such that no air space remains on the incident surface and the transparent member does not adhere to a side face functioning as the total reflection surface of the columnar light guide unit.

2. A light emitting device comprising:

at least one light emitting element having a light emitting part for emitting illumination light;

a substrate to which the light emitting element is fixed;

a spacer having a mirror surface for reflecting the illumination light emitted from the light emitting element; and

at least one columnar light guide unit having an incident surface upon which the illumination light is incident, a total reflection surface for totally reflecting the illumination light coming from the incident surface, and an exit surface having an area larger than that of the incident surface, the exit surface emitting the illumination light totally reflected at the total reflection surface, wherein

the spacer includes an indentation open at least at a top thereof or an opening,

the mirror surface is formed on the indentation or an inner side surface of the opening,

the position of the mirror surface closest to a bottom surface of the spacer is substantially equal to the position of the light emitting unit closest to the substrate in a depth direction of the indentation or the opening from a spacer top surface, and the light emitting element is positioned with respect to the indentation bottom surface of the spacer or the bottom surface of the spacer,

the area of the opening at the top surface of the spacer is larger than the bottom surface area of the indentation or the area of the opening at the bottom surface of the spacer, and

the incident surface of the at least one columnar light guide unit is located in the indentation or on the spacer top surface at the opening, the indentation or the opening is filled with a transparent member, at least the light emitting unit of the light emitting element is shielded from the air by the transparent member, and no air space exists between the incident surface and the transparent member.