JP2005191483A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-intensity light source, in particular a light-emitting device using a semiconductor laser chip which is safe for human eyes. <P>SOLUTION: The light-emitting device comprises a semiconductor laser chip, a reflecting member that receives laser light from the laser chip and reflects the laser light while lengthening a wavelength and degrading coherence, and a package having an opening and accommodating the laser chip and the reflecting member inside. The light-emitting device emits light from the opening by reflecting the laser light from the laser chip by the reflecting member. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting device, and more particularly to a light emitting device using a semiconductor laser chip.

As a background art related to the present invention, a light source is known in which a phosphor mixed in a transparent resin is excited by a light emitting diode (LED) to generate white light (see, for example, Patent Document 1). .
In recent years, light sources using LEDs in this way have begun to be used in place of conventional light bulbs in displays such as traffic lights and instrument panels. Moreover, it is also being applied to lighting devices for general households (for example, desk stands).
Japanese Patent Publication No. 2927279 ([0017]-[0018])

However, the LED chip has an output of several mW to at most 10 mW, and it is difficult to obtain a large output. On the other hand, the semiconductor laser chip has a large output of 30 to 100 mW, but the phase of the light wave is uniform, so-called coherence (coherence), and is harmful to human eyes. There is a problem that it is difficult to use as a light source.
The present invention has been made in view of such circumstances, and provides a light-emitting element that can be used as a general illumination light source by using a semiconductor laser chip and reducing its coherence.

  The present invention includes a semiconductor laser chip, a reflecting member that receives laser light from the laser chip and reflects the laser light with a longer wavelength and a reduced coherence, and has an opening in the laser chip and the reflecting member. And a light-emitting element that reflects the laser light from the laser chip by a reflecting member and emits the light from the opening.

  According to the present invention, the laser light emitted from the semiconductor laser chip is converted into long-wavelength light within the package, the coherence is reduced, and the light is emitted from the package. be able to.

A light-emitting device according to the present invention includes a semiconductor laser chip, a reflecting member that receives laser light from the chip and reflects the laser light with a longer wavelength and a reduced coherence, and the laser chip and the reflecting member having an opening. The laser beam from the laser chip is reflected by a reflecting member and emitted from the opening.
In the present invention, the reflecting member can be composed of a phosphor that is excited by laser light from the semiconductor laser chip and generates fluorescence having a wavelength longer than that of the laser light (lengthens the wavelength to reduce coherence). Fluorescence has no coherence.

  In this case, the phosphor is composed of a base, an activator and a flux, and the base is an inorganic oxide such as zinc, cadmium, magnesium, silicon, yttrium, or other rare earth elements, sulfide, silicate, vanadate, etc. Selected from phosphors or organic phosphors such as fluorescein, eosin, oils (mineral oil), activator is selected from silver, copper, manganese, chromium, eurobium, zinc, aluminum, lead, phosphorus, arsenic, gold, The fluxing agent can be selected from sodium chloride, potassium chloride, magnesium carbonate, and barium chloride.

  In the present invention, the semiconductor laser chip may be a chip that emits purple or blue laser light, and the reflection member may be a fluorescent layer that is excited by the purple or blue laser light to generate white light.

Here, the purple to blue laser light is laser light having a wavelength of 320 to 480 nm, and the fluorescent layer that is excited by the laser light to generate white light includes yttrium, aluminum, and garnet activated by cerium. A phosphor such as Y ₃ Al ₅ O ₁₂ : Ce, Y ₃ (Al _0.6 Ga _0.4 ) ₅ O ₁₂ : Ce, or Y ₃ (Al _0.5 Ga _0.5 ) ₅ O ₁₂ : Ce is preferably used. it can.

Further, the light reflecting surface of the reflecting member may be subjected to a roughening process so that the phase of the incident laser beam is disturbed and reflected.
The surface roughness (unevenness) subjected to the roughening treatment preferably has a height difference of several to several tens of times the wavelength of the incident laser light. As a result, the phase of the incident laser beam is efficiently disturbed, and the coherence is reduced or eliminated.

The package may be formed of a bottomed cylindrical member having the opening, the reflecting member may be provided on the inner surface of the bottom of the cylindrical member, and the opening may be closed with a translucent protective plate.
In this case, if the translucent protective plate has a lens action such as a convex lens, a concave lens, or a cylindrical lens, the light converging and divergence characteristics can be used depending on the application.
The semiconductor laser chip is an edge emitting laser chip that emits laser light from the first and second light emitting end faces, respectively, such that the first light emitting end face faces the reflecting member and the second light emitting end face faces the protective plate. A support member for supporting the semiconductor laser chip may be further provided.

The semiconductor laser chip may be set such that the internal reflectance on the first light emitting end face side is smaller than that on the second light emitting end face side.
A rod-shaped electrode extending from the cylindrical inner wall toward the center may be further provided, the support member may be made of a conductor, and the semiconductor laser chip may be supplied with power through the rod-shaped electrode and the support member.
The semiconductor laser chip includes a first electrode layer, a second electrode layer having a polarity different from that of the first electrode layer, and an active layer that is provided near the first electrode layer between the first and second electrode layers and generates laser light. The first electrode layer may be connected to the support member, and the second electrode layer may be connected to the rod-shaped electrode.
You may further provide the reflecting plate which is provided in the inner surface of a protection plate and reflects the light from a 2nd end surface to the direction of a reflecting member.
Further, the semiconductor laser chip is composed of three semiconductor laser chips that respectively emit blue, green, and red light, and the reflecting member has minute irregularities on the reflecting surface, and receives the laser light from each chip, You may make it reflect, reducing coherence. Note that the coherence can be lowered by a translucent protective plate provided in the opening.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. This does not limit the invention.

First Embodiment FIG. 1 is a top view showing a first embodiment of the light emitting device according to the present invention, and FIG. 2 is a cross-sectional view taken along the line II in FIG.
As shown in these drawings, the package 1 includes a cylindrical metal side wall member 2 and a metal bottom member 3. An edge-emitting semiconductor laser chip 4 is installed at the upper end portion of a metal support member 8 that penetrates the bottom member 3 through a heat radiating member (conductor) 5 at approximately the center inside the package 1. The laser chip 4 emits laser beams L1 and L2 having wavelengths of 350 to 480 nm in two directions parallel to the internal PN junction surface. The inner surface of the bottom member 3 has a concave shape as shown in FIG. 2, and a phosphor layer 6 as a reflecting member is laminated on the surface. The upper opening of the side wall member 2 is closed with a translucent protective plate 7. An aluminum reflector 12 is attached to the center of the inner surface of the protective plate 7.

  Further, the rod-shaped metal terminal 9 is attached so as to penetrate the bottom member 3 through the insulating member 10. The support member 8 is electrically connected to the p-type electrode of the laser chip 4 via the bottom member 3 and the heat radiating member 5, and the metal terminal 9 is connected to the n-type electrode of the laser chip 4 via the strip-shaped metal film 11. Electrically connected. For the metal film 11, a film having a thickness of about 30 μm such as gold, copper, platinum, or aluminum is used. Further, instead of the metal film 11, a fine metal wire such as a gold wire may be used.

  Here, the side wall member 2 and the bottom member 3 are made of aluminum, the heat dissipating member 5, the support member 8, and the terminal 9 are made of copper, and the protective plate 7 is made of epoxy resin. Note that the side wall member 2 and the bottom member 3 may be formed of a copper alloy, an iron alloy, or the like, and the protective plate 7 may be formed of a glass material. The phosphor layer 6 is made of an yttrium / aluminum / garnet phosphor. One light emitting end face (first end face) of the laser chip 4 faces the phosphor layer 6, and the other light emitting end face (second end face) faces the reflector 12. Note that the inside of the package 1 whose opening is closed by the protective plate 7 can be evacuated or filled with an inert gas as necessary.

In such a configuration, when a predetermined drive voltage is applied between the support member 8 and the metal terminal 9, laser beams L 1 and L 2 are emitted from the first and second end surfaces of the laser chip 4, respectively.
The laser beam L1 is reflected directly, and the laser beam L2 is reflected by the reflecting plate 12, and collides with the phosphor layer 6 to excite the phosphor layer 6. As a result, white light having an emission peak in the vicinity of 500 to 600 nm and having no coherence is generated and emitted from the package 1 through the protective plate 7.

  Therefore, the phosphor layer 6 can sufficiently receive the laser beams L1 and L2, efficiently convert the received laser beams L1 and L2 into white light, and can effectively emit the white light from the package 1. It preferably has an area and shape.

In the semiconductor laser chip 4, the internal reflectance (less than 10%) on the first end face side is set smaller than that on the second end face side (90% or more), and the radiation power of the laser light L1 is sufficiently higher than that of the laser light L2. To be bigger.
The semiconductor laser chip 4 includes a p-type electrode (first electrode layer), an n-type electrode (second electrode layer), and an active layer that is provided near the p-type electrode and generates laser light. And the p-type electrode is fixed to the support member 8 through the heat radiating member 5 as described above. This is because the p-type electrode close to the active layer that generates heat during oscillation is fixed to the heat radiating member 5 to efficiently dissipate the heat generated in the active layer.

  Instead of providing the phosphor layer 6 on the concave surface of the bottom member 3, a wavelength conversion material such as a phosphor may be mixed in the protective plate 7. In this case, the laser beams L1 and L2 are converted into visible light when reflected by the concave surface of the bottom member 3 and transmitted through the protective plate 7. As this wavelength conversion material, the same material as the phosphor layer 6 can be used.

Second Embodiment FIG. 3 is a top view showing a second embodiment of the light emitting device according to the present invention, and FIG. 4 is a sectional view taken along the line II-II in FIG.
As shown in these drawings, this embodiment is a partial modification of the first embodiment. An insulating member 13 is attached to the lower surface of the bottom member 3 of the first embodiment, and the support member 8 and the metal terminal. 9 are provided with lead frames 14 and 15 connected to the respective lower end portions.
That is, the light-emitting element is a so-called chip component type (surface mounting), and a higher heat dissipation effect can be obtained when mounted on a substrate.

Third Embodiment FIG. 5 is a top view showing a third embodiment of the light emitting device according to the present invention, and FIG. 6 is a sectional view taken along the line III-III in FIG.
As shown in these drawings, this embodiment is a partial modification of the second embodiment. That is, the support member 8, the metal terminal 9, and the insulating member 10 of the second embodiment are replaced with the support member 8a, the metal terminal 9a, and the insulating members 10a and 10b, respectively. This is equivalent to the second embodiment.
The support member 8 a rises from the lead frame 14 along the outer surfaces of the bottom member 3 and the side wall member 2, penetrates the side wall member 2 in the center direction (horizontal direction), and the tip thereof passes through the heat radiating member 5. The laser chip 4 is supported.

On the other hand, the metal terminal 9a rises along the outer surface of the bottom member 3 and the side wall member 2 with the insulating member 10b interposed from the lead frame 15, and the side wall member 2 passes through the insulating member 10a in the center direction (horizontal direction). It penetrates and the tip is connected to the laser chip 4 through the metal film 11.
In this embodiment, the support member 8 and the metal terminal 9 in the second embodiment are arranged so as not to block the laser beam L1.
Note that the support member 8a, the heat radiating member 5, and the metal terminal 9a in this embodiment are arranged so that the reflected light from the phosphor layer 6 does not block the reflected light as much as possible and the heat radiation effect is obtained. It is configured so that the cross-sectional area in the perpendicular direction is minimized.

1 is a top view of a first embodiment of a light emitting device according to the present invention. It is II sectional view taken on the line of FIG. It is a top view of 2nd Example of the light emitting element by this invention. It is II-II arrow sectional drawing of FIG. It is a top view of 3rd Example of the light emitting element by this invention. FIG. 6 is a cross-sectional view taken along the line III-III in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Package 2 Side wall member 3 Bottom member 4 Laser chip 5 Heat radiating member 6 Phosphor layer 7 Protective plate 8 Support member 9 Metal terminal 10 Insulating member 11 Metal film 12 Reflector

Claims (11)

  A semiconductor laser chip, a reflecting member that receives laser light from the laser chip, increases the wavelength and reflects it with a reduced coherence, and a package that has an opening and accommodates the laser chip and the reflecting member therein A light emitting element that reflects the laser light from the laser chip by a reflecting member and emits the light from the opening.   The light-emitting element according to claim 1, wherein the reflecting member is made of a phosphor that is excited by laser light from a semiconductor laser chip and generates light having a wavelength longer than that of the laser light.   The light-emitting element according to claim 1, wherein the semiconductor laser chip is a chip that emits purple to blue laser light, and the reflection member includes a fluorescent layer that is excited by the purple to blue laser light and generates visible light including white.   2. The light emitting device according to claim 1, wherein the semiconductor laser chip is an edge emitting laser chip that emits laser light from two end faces.   The light emitting device according to claim 1, wherein the package is formed of a bottomed cylindrical member having the opening, the reflecting member is provided on an inner surface of the bottom of the cylindrical member, and the opening is closed by a translucent protective plate. element.   The semiconductor laser chip is an edge-emitting laser chip that emits laser light from the first and second light emitting end faces, respectively, and the semiconductor is such that the first light emitting end face faces the reflecting member and the second light emitting end face faces the protective plate. The light emitting device according to claim 5, further comprising a support member that supports the laser chip.   The light emitting device according to claim 6, wherein the semiconductor laser chip has an internal reflectance on the first light emitting end face side smaller than that on the second light emitting end face side.   The light-emitting element according to claim 6, wherein the support member extends from the inner side wall of the cylindrical member toward the center and supports the laser chip at the tip.   9. The light emitting device according to claim 8, further comprising a rod-shaped electrode extending from the cylindrical inner wall toward the center, wherein the support member is made of a conductor, and the semiconductor laser chip is fed via the rod-shaped electrode and the support member.   The semiconductor laser chip includes a first electrode layer, a second electrode layer having a polarity different from that of the first electrode layer, and an active layer that is provided near the first electrode layer between the first and second electrode layers and generates laser light. The light emitting device according to claim 9, wherein the first electrode layer is connected to the support member and the second electrode layer is connected to the rod-shaped electrode.   The light emitting element according to claim 6, further comprising a reflection plate provided on an inner surface of the protection plate and reflecting light from the second end surface toward the reflection member.

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