JP2008235945A - Light emitting element - Google Patents

Abstract

A light-emitting element that emits light without coherence using a semiconductor laser chip is provided.
A semiconductor laser chip that emits laser light, a coherence reducing member that generates low coherence light by reducing the coherence by receiving the laser light, and the laser chip and the coherence reducing member having an opening therein. A coherence reducing member having a reflecting resin surface roughened by rough deposition of metal so that the phase of incident laser light is disturbed and reflected so as to be reflected from the semiconductor laser laser chip. Is converted into low-coherent light by the coherence reducing member and emitted from the aperture.
[Selection] Figure 1

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 conventional technique 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 (for example, see 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. In contrast, the semiconductor laser chip has a large output of 30 to 50 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 light source by using a semiconductor laser chip and reducing its coherence.

  The present invention includes a semiconductor laser chip that emits laser light, a coherence reducing member that generates low-coherence light by reducing the coherence upon receiving the laser light, and the laser chip and the coherence reducing member that have openings therein. And a coherence reducing member having a reflective resin surface roughened by rough deposition of metal so that the phase of incident laser light is disturbed and reflected so as to be reflected from the semiconductor laser chip. The present invention provides a light emitting device in which laser light is converted into low coherent light by a coherence reducing member and emitted from an opening.

  According to the present invention, since the laser beam emitted from the semiconductor laser chip is emitted from the package with the coherence lowered by the coherence reducing member in the package, a light-emitting element that is safe for the eyes can be provided.

In this invention, the coherence reducing member may be 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. 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. It is selected from phosphors or organic phosphors such as fluorescein, eosin, oils (mineral oil), and the activator is selected from silver, copper, manganese, chromium, eurobium, zinc, aluminum, lead, phosphorus, arsenic, gold, The flux can be selected from sodium chloride, potassium chloride, magnesium carbonate, barium chloride.

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

Here, purple to blue laser light is laser light having a wavelength of 360 to 480 nm, and a 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 coherence reducing member may be a reflecting member having a reflecting surface that has been roughened so that the phase of the incident laser beam is disturbed and reflected.
In this case, the reflecting member is subjected to a so-called fine matte treatment, such as a surface of a metal such as aluminum that has been finely roughened by polishing or etching, or a metal that has been vapor-deposited on the resin surface. It has a reflective surface.
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 semiconductor laser chip may be an edge-emitting laser chip that emits purple or blue laser light in two directions parallel to the PN junction surface, or the semiconductor laser chip may be a surface-emitting laser chip. Good.
In the present invention, the package may include a positive terminal and a negative terminal for applying a DC voltage to the semiconductor laser chip.
The package may include a metal block for radiating heat generated by the semiconductor laser chip.
Further, the semiconductor laser chip may be composed of at least one of three laser chips that respectively emit red, green, and blue.

The package may have a translucent plate fitted in the opening.
In this case, the light transmitted from the package may be condensed or diverged by providing the translucent plate with a convex or concave lens.
Moreover, you may mix a fluorescent substance in a translucent board.
The coherence reducing member may be composed of a fluorescent member that converts light from the semiconductor laser chip into fluorescence, and a reflective member that reflects the fluorescence emitted from the fluorescent member to 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 a light emitting device according to the present invention, and FIG. 2 is a cross-sectional view taken along the line AA of FIG.
As shown in these drawings, the package 1 includes a side wall member 2 and a bottom member 3. An edge-emitting type semiconductor laser chip 4 is installed on a metal bottom member (stem) 3 via a metal mount member 5 at approximately the center inside the package 1. The semiconductor 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. As shown in FIG. 2, the inner wall of the side wall member 2 has a concave shape, and a phosphor layer 6 is laminated on the inner wall. The upper opening of the side wall member 2 is closed with a translucent protective plate 7.

  Two rod-shaped metal terminals 8 and 9 are provided vertically on the bottom member 3, the metal terminal 8 is directly coupled to the bottom member 3, and the metal terminal 9 penetrates the bottom member 3 through an insulating member 10. Attached to. The metal terminal 8 is electrically connected to the n electrode of the semiconductor laser chip 4 through the bottom member 3 and the mount member 5, and the metal terminal 9 is electrically connected to the p electrode of the laser chip 4 through the metal thin wire 11. Connected. For the thin metal wire 11, a wire having a diameter of about 30 μm such as gold, copper, platinum, or aluminum is used.

  Here, the side wall member 2 is formed of a polyimide resin, and the protective plate 7 is formed of an epoxy resin. The phosphor layer 6 is made of an yttrium / aluminum / garnet phosphor. Note that the inside of the package 1 whose opening is closed by the protective plate 7 can be evacuated as necessary.

  In such a configuration, when a predetermined drive voltage is applied between the metal terminals 8 and 9, the laser beams L1 and L2 are emitted from the semiconductor laser chip 4, respectively. The laser beams L1 and L2 collide 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 in the directions of arrows B and C, respectively.

  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.

  When the laser beams L1 and L2 have a light component that is reflected by the phosphor layer 6 and emitted from the package 1 as it is, if the phosphor is mixed in the protective plate 7 in advance, the light component causes fluorescence. The body can be excited. This prevents the laser beams L1 and L2 from being emitted from the package 1 as they are. For this phosphor, the same material as that of 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 DD in FIG.
As shown in these drawings, this embodiment is a part of the first embodiment, and the package 1 in the first embodiment is replaced with a package 1a. That is, the phosphor layer 6, the bottom member 3, and the metal terminals 8 and 9 of the first embodiment are replaced with the reflective layer 6a, the insulating substrate 3a, and the metal wiring patterns 8a and 9a, respectively. Other configurations are the same as those of the first embodiment.
Here, the reflective layer 6a is formed into a satin-like surface by depositing aluminum on the inner wall of the side wall member 2, and its surface roughness (unevenness) is about 10 times the wavelength of the laser beams L1 and L2, that is, 5 μm. Has an average height difference.

In such a configuration, when a predetermined drive voltage is applied between the wiring patterns 8a and 9a, the laser beams L1 and L2 emitted from the semiconductor laser chip 4 are irregularly reflected by the reflection layer 6a, and the phase is disturbed to cause coherence. And is emitted from the package 1a in the directions of arrows B and C.
In this embodiment, a chip that emits light having an arbitrary wavelength from purple to red can be used as the laser chip 4, but the surface roughness of the reflective layer 6a is optimized in accordance with the wavelength. Must be set.

Third Embodiment FIGS. 5 and 6 show a third embodiment of the present invention and correspond to FIGS. 3 and 4 of the second embodiment, respectively. That is, in the third embodiment, the metal mount member 5 and the metal pattern 8a in the second embodiment are replaced with the metal heat dissipation block 5a, and other configurations are the same as those of the second embodiment.

In this embodiment, the heat dissipating block 5a is installed so as to penetrate the insulating substrate 3a and a part thereof is exposed from the package 1a, and the heat capacity can be made sufficiently larger than that of the mount member 5 (FIG. 4).
Therefore, in this embodiment, since the heat generated by the semiconductor laser chip 4 can be absorbed and radiated with high heat dissipation efficiency, a relatively large capacity semiconductor laser chip can be used.

Fourth Embodiment FIG. 7 is a longitudinal sectional view showing a fourth embodiment of the light emitting device according to the present invention.
As shown in the figure, the package 1b includes a side wall member 2a and an insulating substrate 3a. The insulating substrate 3a includes metal wiring patterns 8b and 9b. The semiconductor laser chip 4a is mounted on an upper portion of a metal heat dissipation block 5b provided through the insulating substrate 3a. The inner wall of the side wall member 2a has a concave shape, and the phosphor layer 6b is laminated on the inner wall. The lateral opening of the side wall member 2a is closed with a translucent protective plate 7a. The semiconductor laser chip 4a in this embodiment has a configuration in which one of the two laser light emitting end faces is increased to emit laser light from one side surface by increasing the laser light emissivity.

Accordingly, the semiconductor laser chip 4a is installed obliquely by the heat dissipation block 5b so that the laser light L3 emitted from the laser light emitting end face efficiently irradiates the phosphor layer 6a.
Further, the metal wiring patterns 8b and 9b are connected to the n electrode and the p electrode of the semiconductor laser chip 4a through the fine metal wires 11a and 11b, respectively.
Here, the semiconductor laser chip 4a is a chip that emits laser light having the same wavelength as that of the chip 4 of the first embodiment. The phosphor layer 6b, the side wall member 2a, the protective plate 7a, the thin metal wires 11a, 11b, and the like are the first. It is formed of the same material as that of the example.

In such a configuration, when a predetermined drive voltage is applied between the wiring patterns 8b and 9b, the laser beam L3 is emitted from the semiconductor laser chip 4a. The laser beam L3 collides with the phosphor layer 6b and excites the phosphor layer 6b. As a result, white light without coherence is generated and emitted from the package 1b in the direction of arrow E.
If the wavelength of the laser beam of the semiconductor laser chip 4a and the corresponding phosphor material of the phosphor layer 6a are appropriately selected, light of emission color having no coherence can be emitted from the package 1b according to the application. it can.

Fifth Embodiment FIG. 8 is a top view showing a fifth embodiment of the light emitting device according to the present invention, and FIG. 9 is a cross-sectional view taken along line FF in FIG.
As shown in these drawings, the package 1c includes a side wall member 2c having openings in the upper and side portions, and a substrate 3b that closes the side opening. The substrate 3b is composed of an insulating substrate having wiring patterns 8c to 8e and 9c to 9e. The three semiconductor laser chips 4b to 4d are mounted on a metal mount member 5c in a vertical row at substantially the center inside the package 1c. As shown in FIG. 8, the mount member 5c is installed to penetrate the substrate 3b. The inner wall of the side wall member 2c has a concave shape as shown in FIG. 9, and a reflective layer 6c is laminated on the inner wall. The reflective layer 6c is formed in the same manner as the reflective layer 6a of the second embodiment. The n and p electrodes of the semiconductor laser chips 4b to 4d are connected to the wiring patterns 8c to 8e and 9c to 9e, respectively, through thin metal wires. The upper opening of the side wall member 2c is closed with a translucent protective plate 7b. Here, as the semiconductor laser chips 4b to 4d, chips that emit laser beams of R (red), G (green), and B (blue) are used.

  In such a configuration, when drive voltages are applied to the semiconductor laser chips 4b to 4d through the wiring patterns 8c to 8e and 9c to 9e, R, G, and B laser beams are emitted from the semiconductor laser chips 4b to 4d, respectively. The light is emitted and irregularly reflected by the reflective layer 6c. Thereby, the phase of each laser beam is disturbed and converted into light having no coherence. The R, G, and B laser beams having no coherence are mixed with each other to become white light, and are emitted from the package 1c through the protective plate 7b.

1 is a top view of a first embodiment of a light emitting device according to the present invention. It is AA arrow sectional drawing of FIG. It is a top view of 2nd Example of the light emitting element by this invention. It is DD sectional view taken on the line of FIG. It is a top view of 3rd Example of the light emitting element by this invention. It is DD sectional view taken on the line of FIG. It is a longitudinal cross-sectional view of 4th Example of the light emitting element by this invention. It is a top view of 5th Example of the light emitting element by this invention. It is FF arrow sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Package 2 Side wall member 3 Bottom member 4 Semiconductor laser chip 5 Mount member 6 Phosphor layer 7 Protection plate 8 Metal terminal 9 Metal terminal 10 Insulating member 11 Metal thin wire L1 Laser beam L2 Laser beam

Claims (7)

A semiconductor laser chip that emits laser light; a coherence reducing member that receives laser light to reduce coherence to generate low coherence light; and a package that has an opening and accommodates the laser chip and the coherence reducing member therein. The coherence reducing member has a reflective resin surface roughened by rough deposition of metal so that the phase of incident laser light is disturbed and reflected, and the laser light from the semiconductor laser chip is coherent. A light emitting device that is converted into low coherent light by the lowering member and emitted from the opening. 2. The light emitting device according to claim 1, wherein the semiconductor laser chip is an edge-emitting laser chip that emits violet to blue laser light in two directions parallel to the PN junction surface. The light emitting device according to claim 1, wherein the semiconductor laser chip is a surface emitting laser chip. The light emitting device according to claim 1, wherein the package includes a positive electrode terminal and a negative electrode terminal for applying a DC voltage to the semiconductor laser chip. The light emitting device according to claim 1, wherein the package includes a metal block for radiating heat generated by the semiconductor laser chip. 2. The light emitting device according to claim 1, wherein the semiconductor laser chip comprises at least one of three laser chips that respectively emit red, green, and blue. The light emitting device according to claim 1, wherein the package has a light transmitting plate fitted in the opening.

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