JP2012089316A - Light source device, and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device of reflection type which can attain sufficiently high luminance compared with a conventional one and prevents color unevenness in light-emitting points in a phosphor layer.SOLUTION: The light source device of reflection type is provided with a solid light source 5 which emits light of a prescribed wavelength out of the wavelength regions from ultraviolet light to visible light, a phosphor layer 2 including at least one kind of phosphor which is excited by excitation light from the solid light source 5 and emits light of fluorescence with a longer wavelength than the emission wavelength of the solid light source 5, and a light reflecting substrate 6 which is installed on a surface on opposite side to the incident face of the excitation light out of the surface of the phosphor layer 2. The solid light source 5 and the phosphor layer 2 are arranged separated spatially. The shape and cross-section of beams on the incident face of the phosphor layer of the excitation light from the solid light source 5 entering into the phosphor layer 2 are nearly equal to the shape and area of the whole incident face of the phosphor layer.

Description

  The present invention relates to a light source device and an illumination device.

  A light source device combining an optical semiconductor such as an LED and a phosphor layer has been widely used. However, in recent years, the brightness has been increased, and its application range such as general lighting and automobile headlamps has been expanded. It is considered that such light source devices will continue to be widely used in various applications by increasing the luminance.

  As a means for increasing the brightness of a light source device combining such an optical semiconductor and a phosphor layer, it is conceivable to increase the excitation light intensity from the optical semiconductor by supplying a large current to the optical semiconductor. Heat is generated in the phosphor layer, and in the phosphor layer, the fluorescence intensity decreases due to discoloration of the resin component or temperature quenching of the phosphor. Therefore, as a result, the emission intensity is saturated and decreased, and it is difficult to increase the luminance of the light source device that combines the optical semiconductor and the phosphor layer.

  Here, the discoloration of the resin component in the phosphor layer means that the phosphor layer is usually formed into a fixed shape with good reproducibility. This is a phenomenon in which the resin component is discolored when the resin component is heated to about 200 ° C. or higher. Since the resin component is inherently transparent, if the resin component is discolored by heat, it absorbs a part of the excitation light from the optical semiconductor and the fluorescence from the phosphor layer, which prevents high brightness. It was.

  The temperature quenching of the phosphor is a phenomenon in which the fluorescence intensity decreases when the phosphor is heated. If the fluorescence intensity decreases due to temperature quenching, the energy that has not been converted to fluorescence becomes heat, so the amount of heat generated by the phosphor increases, the temperature of the phosphor rises, temperature quenching proceeds, and the fluorescence intensity further decreases. This happens. For this reason, temperature quenching of the phosphors generated by heat has also been a factor that hinders high brightness.

  In order to solve these problems, Patent Document 1 proposes a light source device using a phosphor layer that does not contain a resin. In this case, since the phosphor layer does not contain a resin component, discoloration does not occur, and furthermore, temperature quenching does not occur because the phosphor layer is a ceramic layer of a phosphor with low temperature sensitivity, so that high brightness can be achieved. is there. In addition, as shown in FIG. 1, the phosphor layer 92 is directly bonded to the optical semiconductor 95 to dissipate heat generated in the phosphor layer 92 to the optical semiconductor (solid light source) 95 side.

JP 2006-005367 A

  By the way, in the conventional light source device in which the optical semiconductor 95 and the phosphor layer 92 are directly joined as shown in FIG. 1, the heat of the phosphor layer 92 is intended to be dissipated to the optical semiconductor 95 side. When the excitation light intensity of the optical semiconductor 95 is increased, heat is generated not only in the phosphor layer 92 but also in the optical semiconductor 95, so that the heat generation in the phosphor layer 92 is dissipated from the side of the optical semiconductor 95 that is also generating heat. The efficiency of heat dissipation is not good, and there is a limit to increasing the brightness.

  The inventor of the present application adopts a configuration in which the optical semiconductor and the phosphor layer are spatially separated from each other in the prior application (Japanese Patent Application No. 2009-286397) of the present application in order to achieve a sufficiently high brightness as compared with the prior art. It was.

  However, the inventors of the present application have found a phenomenon in which unevenness occurs in the emission color in the light emitting point on the phosphor layer while examining the configuration in which the optical semiconductor and the phosphor layer are arranged spatially apart. FIG. 2A shows a light emitting point (light emission) in a phosphor layer when a blue semiconductor laser is used as an optical semiconductor and a YAG phosphor ceramic, which is a yellow phosphor containing no resin component, is used as a phosphor layer. An outline of the pattern) is shown. The cross-sectional area of the beam on the phosphor layer incident surface (surface on the side of the phosphor layer on which the excitation light is incident) 60 of the excitation light from the blue semiconductor laser used here is the phosphor layer incident It was much smaller than the area of the entire surface 60. In FIG. 2 (a), the area indicated by the symbol A is the center of the light emitting point (the portion corresponding to the cross-sectional area of the beam of the excitation light from the blue semiconductor laser on the phosphor layer incident surface 60). The region indicated by is the peripheral portion of the light emitting point. Here, the light intensity (brightness) of the beam of the excitation light from the blue semiconductor laser on the phosphor layer incident surface 60 is Lambertian, and is the strongest at the center O of the central portion A of the emission point. At the outer edge AE of the central part A of the light emitting point, the light intensity (brightness, light quantity) is about 50% of the center O of the central part A of the light emitting point, and at the outer edge BE of the peripheral part B of the light emitting point. The light intensity (brightness, light quantity) is about 10% of the center O of the part A. FIG. 2B shows the measurement results of the chromaticity of the central portion A of the light emitting point and the peripheral portion B of the light emitting point. From the result of FIG. 2B, the central portion A of the light emitting point has a sufficient amount of excitation light from the blue semiconductor laser, and is white due to a mixture of a sufficient amount of blue excitation light and yellow fluorescence. On the other hand, the peripheral portion B of the light emitting point has a small amount of excitation light from the blue semiconductor laser (that is, the amount of blue light is small) and exhibits chromaticity on the yellow side with respect to the central portion A of the light emitting point. I understand that.

  When such a light source device having color unevenness within the light emitting point (light emission pattern) is actually used in an illumination device, the illumination light also has color unevenness, which is a serious problem in practice.

  The present invention provides a light source device and an illuminating device that can achieve a sufficiently high luminance as compared with the prior art and can prevent color unevenness in a light emitting point (light emitting pattern) in a phosphor layer. The purpose is to provide.

  In order to achieve the above object, the invention described in claim 1 is excited by a solid light source that emits light of a predetermined wavelength in a wavelength region from ultraviolet light to visible light, and excitation light from the solid light source. A phosphor layer including at least one kind of phosphor that emits fluorescence having a wavelength longer than the emission wavelength of the solid-state light source, and a surface of the phosphor layer opposite to a surface on which excitation light is incident. A reflection-type light source device including a light-reflecting substrate provided, wherein the solid-state light source and the phosphor layer are arranged spatially apart from the solid-state light source incident on the phosphor layer The shape and the cross-sectional area of the beam of the excitation light on the phosphor layer entrance surface are substantially equal to the shape and area of the entire phosphor layer entrance surface.

  Further, the invention according to claim 2 is the light source device according to claim 1, wherein when the excitation light from the solid light source is incident on the periphery of the phosphor layer, absorption means for absorbing the excitation light, or A diffusing means for diffusing the excitation light is provided.

  The invention described in claim 3 is an illumination device characterized in that the light source device described in claim 1 or claim 2 is used.

  According to the first and second aspects of the invention, the solid light source that emits light of a predetermined wavelength in the wavelength region from ultraviolet light to visible light, and the solid that is excited by the excitation light from the solid light source A phosphor layer including at least one kind of phosphor that emits fluorescence having a wavelength longer than the emission wavelength of the light source, and a surface of the phosphor layer that is opposite to the surface on which excitation light is incident. A reflection type light source device in which the solid light source and the phosphor layer are spatially separated from each other, and excitation from the solid light source incident on the phosphor layer Since the shape and cross-sectional area of the light beam on the phosphor layer entrance surface (the surface of the phosphor layer surface on which excitation light is incident) are substantially equal to the shape and area of the entire phosphor layer entrance surface It is possible to achieve a sufficiently high brightness compared to conventional ones and It is possible to prevent the color unevenness in the light emitting point (light emission pattern) of the layer.

  In particular, according to the invention described in claim 2, in the light source device according to claim 1, when the excitation light from the solid-state light source is incident on the periphery of the phosphor layer, absorption means for absorbing the excitation light, Alternatively, since a diffusing means for diffusing the excitation light is provided, it absorbs the excitation light that has not entered the phosphor layer (extruded from the phosphor layer) (for example, excitation light that is coherent light from a semiconductor laser). It can be absorbed by the means, or can be diffused by the diffusing means, and the excitation light that has not entered the phosphor layer (extruded from the phosphor layer) is directly projected as illumination light, causing harm to the human body. Risk can be prevented.

  Further, according to the invention described in claim 3, since the illumination device is characterized in that the light source device described in claim 1 or claim 2 is used, the illumination light can also prevent color unevenness. it can.

It is a figure which shows the conventional light source device. It is a figure for demonstrating the color nonuniformity in a light emission point (light emission pattern). It is a figure which shows the example of 1 structure of the light source device of this invention. FIG. 6 is a diagram for explaining a case where the shape and the cross-sectional area of the excitation light from the solid-state light source incident on the phosphor layer on the phosphor layer incident surface are substantially equal to the shape and area of the entire phosphor layer incident surface. is there. It is a figure which shows the other structural example of the light source device of this invention. It is a figure which shows the other structural example of the light source device of this invention. It is a figure which shows the other structural example of the light source device of this invention. It is a figure which shows the other structural example of the light source device of this invention. It is a figure which shows the other structural example of the light source device of this invention. It is a figure which shows the other structural example of the light source device of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIGS. 3A and 3B are diagrams showing a configuration example of the light source device of the present invention. 3A is a front view of the whole, and FIG. 3B is a plan view of a portion where a phosphor layer is provided. Referring to FIG. 3A, the light source device 10 is excited by a solid light source 5 that emits light having a predetermined wavelength in a wavelength region from ultraviolet light to visible light, and excitation light from the solid light source 5. The phosphor layer 2 containing at least one kind of phosphor that emits fluorescence having a wavelength longer than the emission wavelength of the solid-state light source 5 and the surface of the phosphor layer 2 opposite to the surface on which excitation light is incident A light-reflective substrate 6 provided on the side surface, and the solid light source 5 and the phosphor layer 2 are spatially separated from each other.

  Here, as shown in FIGS. 3 (a) and 3 (b), the phosphor layer 2 is attached to the light-reflecting substrate 6 by a joint 7.

  As described above, the light source device 10 basically has the solid light source 5 and the phosphor layer 2 arranged spatially separated in the same manner as the prior application (Japanese Patent Application No. 2009-286397) of the present application. The light-reflective substrate 6 provided on the surface opposite to the surface on the side of the layer 2 on which the excitation light from the solid light source 5 is incident (in the present invention, this surface is referred to as the phosphor layer incident surface). A method of taking out light such as fluorescent light by using reflection by the above (hereinafter referred to as a reflection method or a reflection type) is employed. Thereby, it is possible to achieve a sufficiently high luminance as compared with the conventional case. More accurately, the reflection type or reflection type light source device emits light from the phosphor layer 2 when the phosphor layer 2 is irradiated with excitation light from the solid light source 5 as shown in FIG. Among the fluorescent components to be generated, the light source device uses a component that emerges on the solid light source 5 side. At this time, the reflection component of the excitation light is also used, and it may be combined with the fluorescent component as illumination light.

  By the way, in the present invention, the phosphor layer incident surface of excitation light from the solid light source 5 incident on the phosphor layer 2 attached to the light reflective substrate 6 (from the solid light source 5 out of the surfaces of the phosphor layer 2). The shape and cross-sectional area of the beam on the surface on the side where the excitation light is incident are set to be substantially equal to the shape and area of the entire phosphor layer incident surface. Here, the shape and the cross-sectional area of the beam on the phosphor layer incident surface of the excitation light from the solid light source 5 incident on the phosphor layer 2 are substantially equal to the shape and area of the entire phosphor layer incident surface. For example, as shown in FIGS. 4A and 4B, the shape of the beam 17 of the excitation light from the solid light source 5 incident on the phosphor layer 2 on the phosphor layer incident surface 16 is the phosphor layer incident surface 16. The shape is almost the same as the whole shape (in the example of FIGS. 4A and 4B, the shape of the beam 17 on the phosphor layer incident surface 16 is substantially rectangular, but the corners are rounded). The cross-sectional area of the beam 17 on the phosphor layer incident surface 16 of the excitation light from the solid light source 5 incident on the phosphor layer 2 is the total area of the phosphor layer incident surface 16. It means that it is in the range of 80% to 120%. Specifically, in the example of FIGS. 4A and 4B, the width BY in the longitudinal direction Y of the beam 17 on the phosphor layer incident surface 16 of the excitation light is equal to the longitudinal direction Y of the entire phosphor layer incident surface 16. 4A, the length BX of the beam 17 in the lateral direction X of the excitation light on the phosphor layer incident surface 16 is the lateral direction of the entire phosphor layer incident surface 16 in FIG. In FIG. 4B, the length BX of the beam 17 in the lateral direction X of the excitation light on the phosphor layer incident surface 16 is equal to the lateral direction X of the entire phosphor layer incident surface 16 in FIG. It is 120% of the length PX. 4A and 4B, the width BY in the longitudinal direction Y of the beam 17 on the phosphor layer incident surface 16 of the excitation light is equal to the width PY in the longitudinal direction Y of the entire phosphor layer incident surface 16. Although the same, the length BX in the lateral direction X of the beam 17 on the phosphor layer incident surface 16 of the excitation light is made the same as the length PX in the lateral direction X of the entire phosphor layer incident surface 16. good. As described above, the width BY in the longitudinal direction Y of the beam 17 and the width PY in the longitudinal direction Y of the entire phosphor layer entrance surface 16 or the lateral direction X of the beam 17 on the phosphor layer entrance surface 16 of the excitation light. By making the length BX equal to the length PX in the horizontal direction X of the entire phosphor layer incident surface 16, color unevenness in the vertical direction or the horizontal direction can be further reduced.

  As shown in FIGS. 4A and 4B, in order to make the shape of the beam 17 on the phosphor layer incident surface 16 substantially rectangular, the emission of an optical semiconductor (such as a light emitting diode or a semiconductor laser) is performed. This can be realized by providing a collimating lens (not shown) at the mouth and shaping the shape of the light emitted from the optical semiconductor (such as a light emitting diode or a semiconductor laser) (usually a circular shape) with the collimating lens. However, it is difficult to produce a perfect rectangular beam, and usually a substantially rectangular shape such as the beam 17 shown in FIGS. The cross-sectional area of the beam 17 on the phosphor layer incident surface 16 is the phosphor layer when the phosphor layer 2 is irradiated with the beam 17 of excitation light from an optical semiconductor (such as a light emitting diode or a semiconductor laser). The area of the beam 17 on the incident surface 16 is referred to. The cross-sectional area of the beam 17 on the phosphor layer incident surface 16 changes the distance between the exit of an optical semiconductor (such as a light emitting diode or a semiconductor laser) and the collimating lens. By adjusting, it is possible to adjust. The cross-sectional area of the beam 17 on the phosphor layer incident surface 16 can also be adjusted by adjusting the incident angle of the excitation light to the phosphor layer 2. For example, when the excitation light is incident on the phosphor layer 2 at an incident angle of 90 °, the beam 17 on the phosphor layer incident surface 16 is cut off when incident at an incident angle of 45 °. The area can be increased. Further, the shape and cross-sectional area of the beam 17 on the phosphor layer incident surface 16 can be adjusted by arbitrarily designing the curved surface of the collimating lens. Thereby, for example, even if the shape of the phosphor layer 2 is other than a rectangular shape, the shape of the beam 17 can be arbitrarily adjusted, so that irradiation light having the same shape as the phosphor layer 2 is realized. It becomes possible to do. In the present invention, it is assumed that the solid light source 5 includes not only an optical semiconductor (such as a light emitting diode or a semiconductor laser) but also an optical system such as a collimating lens. Further, the cross-sectional area of the beam 17 can be measured by arranging a beam profiler having a CCD camera instead of the phosphor layer 2 and making the beam 17 incident on the profiler.

  Thus, in the present invention, the shape and cross-sectional area of the beam on the phosphor layer incident surface of the excitation light from the solid light source incident on the phosphor layer are substantially equal to the shape and area of the entire phosphor layer incident surface. Thus, excitation light and fluorescence can be extracted from the entire surface of the phosphor layer 2 at substantially the same ratio (excitation light color (for example, blue) and fluorescence color (for example, blue) and fluorescence color (from the entire surface of the phosphor layer 2). As a result, color unevenness in the light emission points (light emission pattern) as shown in FIG. 2A can be suppressed. In other words, when, for example, a blue semiconductor laser is used as the optical semiconductor and a YAG phosphor ceramic, which is a yellow phosphor containing no resin component, is used as the phosphor layer 2, almost the entire phosphor layer 2 has a light emitting point. Since the peripheral part B of the light emitting point can be almost eliminated, almost the entire surface of the phosphor layer 2 emits white light by mixing a sufficient amount of blue excitation light and yellow fluorescence. Thus, the yellow light emission portion can be almost eliminated, and the color unevenness in the light emission point (light emission pattern) as shown in FIG. 2A can be suppressed. As described above, the present invention can be applied to the case where the excitation light color and the fluorescence color are mixed and used.

  Further, in the present invention, when a semiconductor laser is used for the solid light source 5, the excitation light (excitation light that is coherent light) from the solid light source 5 that is not incident on the phosphor layer 2 (that protrudes from the phosphor layer 2) is generated. It is intended to prevent it from being directly projected as illumination light and causing harm to the human body. Specifically, in order to construct a reflective light source device using a semiconductor laser as the solid light source 5, the phosphor layer 2 is placed on the light reflective substrate 6 having a high reflectance in order to increase the emission intensity as described above. When the beam cross-sectional area of the excitation light from the solid light source 5 is larger than the area of the phosphor layer incident surface (that is, the beam 17 of the excitation light from the solid light source 5 on the phosphor layer incident surface 16 is provided. When the cross-sectional area is in the range of 100% to 120% of the total area of the phosphor layer incident surface 16 (for example, as in FIG. 4B), the phosphor layer 2 was not incident ( Excitation light that protrudes from the phosphor layer 2 is reflected by the light-reflecting substrate 6, and the excitation light that is coherent light is projected as illumination light as it is, which may cause harm to the human body. Further, even if the cross-sectional area of the excitation light beam from the solid light source 5 and the area of the phosphor layer incident surface are substantially the same or smaller (that is, the phosphor layer incident surface 16 of the excitation light from the solid light source 5). Even if the cross-sectional area of the beam 17 above is in the range of 80% to 100% of the total area of the phosphor layer entrance surface 16 (for example, as shown in FIG. 4A), it is used. If the optical axis is shifted due to external vibrations, a similar phenomenon may occur.

  Therefore, in the light source device 10 shown in FIGS. 3A and 3B, the absorbing means 9 that absorbs the excitation light when the excitation light from the solid light source 5 is incident is provided around the phosphor layer 2. 3A and 3B, the absorbing means 9 is an absorbing member (for example, a black member) provided on the light reflective substrate 6 so as to surround the phosphor layer 2.

  In this way, by providing the absorbing means 9 around the phosphor layer 2, the excitation light that has not entered the phosphor layer 2 (extruded from the phosphor layer 2) is absorbed by the absorbing means 9, and is as described above. Danger can be prevented.

  The absorbing means 9 is not limited to the configuration shown in FIGS. 3A and 3B, and various modifications can be made. For example, the absorbing means 9 can be as shown in FIGS. 5 (a), 5 (b), 6 (a), 6 (b). That is, in the example of FIGS. 5A and 5B, the absorbing means 9 is configured as an absorbing material (for example, a black material) provided in the concave portion of the light reflective substrate 6 around the phosphor layer 2. 6 (a) and 6 (b), the absorbing means 9 is an absorbing member (for example, an enclosing member that surrounds the phosphor layer 2 on the light reflective substrate 6 and covers a part of the upper surface of the phosphor layer 2). Black member).

  Further, in each of the above-described examples, the excitation light that is coherent light is projected as illumination light and prevents the danger of harming the human body. However, when the excitation light from the solid light source 5 is incident, the excitation light is absorbed. The absorbing means 9 is provided around the phosphor layer 2. Instead of the absorbing means 9, a diffusion means for diffusing the excitation light when the excitation light from the solid light source 5 is incident is provided around the phosphor layer 2. It can also be provided.

  FIGS. 7A and 7B are views showing a light source device 20 in which a diffusing unit 19 is provided instead of the absorbing unit 9 in the configuration of FIGS. 3A and 3B. That is, in the light source device 20 of FIGS. 7A and 7B, the diffusing means 19 that diffuses the excitation light when the excitation light from the solid light source 5 is incident is provided around the phosphor layer 2. 7A and 7B, the diffusing unit 19 is a diffusing member (for example, a white member) provided on the light reflective substrate 6 so as to surround the phosphor layer 2.

  As described above, by providing the diffusing unit 19 around the phosphor layer 2, the diffusing unit 19 diffuses the excitation light that has not entered the phosphor layer 2 (extruded from the phosphor layer 2), as described above. Danger can be prevented.

  The diffusing means 19 is not limited to the configuration shown in FIGS. 7A and 7B, and various modifications can be made. For example, the diffusing means 19 can be as shown in FIGS. 8A, 8B, 9A, 9B, 10A, 10B. That is, in the example of FIGS. 8A and 8B, the diffusing unit 19 is configured as a diffusing material (for example, a white material) provided in the concave portion of the light reflective substrate 6 around the phosphor layer 2. 9 (a) and 9 (b), the diffusing means 19 is a diffusing member (for example, a member on the light-reflecting substrate 6 that surrounds the phosphor layer 2 and covers a part of the upper surface of the phosphor layer 2). 10 (a) and 10 (b), the diffusing means 19 is configured as a diffusive microstructure (diffusion surface) provided on the surface of the light reflective substrate 6. .

  As described above, by providing the absorbing means 9 or the diffusing means 19 around the phosphor layer 2, excitation light from the solid light source 5 that has not entered the phosphor layer 2 (extruded from the phosphor layer 2) ( Excitation light that is coherent light) is projected as illumination light and can be prevented from harming the human body.

  In the present invention, the phosphor layer 2 includes a phosphor that absorbs excitation light and emits fluorescence having a wavelength longer than that of the excitation light. Phosphors include organic substances, inorganic substances, and organic-inorganic composites, but it is desirable to use inorganic phosphors having excellent reliability. The phosphor layer 2 can be formed by a method in which the phosphor is dispersed in a matrix such as resin or glass, or a method that does not substantially contain a resin component made only of an inorganic substance. In order to achieve high brightness, it is preferable to use a phosphor layer that does not substantially contain a resin component for the phosphor layer 2. Here, the phosphor layer substantially free of the resin component means that the resin component normally used for forming the phosphor layer is 5 wt% or less of the phosphor layer. For realizing such a phosphor layer, a phosphor powder dispersed in glass, a glass phosphor in which a luminescent center ion is added to a glass matrix, a phosphor single crystal or a phosphor polycrystal ( Hereinafter, phosphor ceramics). The phosphor ceramic includes a polycrystalline body made of a phosphor and a ceramic having a composition different from that of the phosphor. The phosphor ceramic is a lump of phosphor that is formed by firing a material into an arbitrary shape before firing in the phosphor manufacturing process. Phosphor ceramics may use an organic substance as a binder in the molding process in the manufacturing process. However, since the organic component is burned off by providing a degreasing process after molding, the organic resin component is not included in the phosphor ceramic after firing. Only 5 wt% or less remains. Accordingly, since most of the phosphor layer substantially free of the resin component is composed of only an inorganic substance, discoloration due to heat does not occur. In addition, glass or ceramics made of only an inorganic substance generally has a higher thermal conductivity than a resin, and thus is advantageous in heat dissipation from the phosphor layer to the substrate. In particular, phosphor ceramics are preferable because they generally have higher thermal conductivity than glass and are less expensive to manufacture than single crystals.

  In addition, since the light-reflecting substrate 6 plays the role of a reflecting surface of the excitation light, it is necessary to use a substrate having a reflectance with respect to the excitation light of 95% or more, particularly 99% or more. desirable. The light reflective substrate 6 also serves to dissipate the heat dissipated from the phosphor layer to the outside and to serve as a support substrate for the phosphor layer. For this reason, high light reflection characteristics, heat transfer characteristics, and workability are required. As the light-reflective substrate 6, a metal substrate, oxide ceramics such as alumina, non-oxide ceramics such as aluminum nitride, and the like can be used, but a metal substrate having particularly high light-reflecting characteristics, heat transfer characteristics, and workability. It is desirable to use

  In addition, a resin, an organic adhesive, an inorganic adhesive, a low-melting glass, a metal brazing, or the like can be used for the joint 7 between the phosphor layer 2 and the light reflective substrate 6. In order to utilize the reflectance of the light reflective substrate 6, it is desirable that the joint portion 7 has high transparency, and it is desirable to use a resin typified by a silicone resin or an inorganic adhesive. On the other hand, since the joining portion 7 plays a role of dissipating heat from the phosphor layer 2, a conductive adhesive containing metal brazing or a metal component is desirable if importance is attached to heat transfer characteristics.

  The absorbing means 9 may be anything that can absorb excitation light, such as black resin, or a colored filter member that absorbs at least excitation light (a filter in which a dye that absorbs at least excitation light is mixed in plastic), or the like. Can be used. Here, the black resin is obtained by dispersing black powder in a transparent resin. As the transparent resin, a silicone resin, an epoxy resin, a silicon epoxy resin, or the like can be used. As the black powder, metal powder, ceramic black pigments, organic black pigments, and the like can be used. First, a resin and black powder are kneaded, placed around or on the phosphor layer 2 on the light-reflective substrate 6 by using a method such as printing or dispensing, and cured as it is in a curing furnace. In this way, a configuration as shown in FIGS. 3A and 3B can be realized. If the light reflective substrate 6 is first provided with a recess, the configuration shown in FIGS. 5A and 5B can be realized by the same method. Furthermore, a configuration as shown in FIGS. 6A and 6B covering a part of the upper surface of the phosphor layer 2 can be realized. In addition, when a filter in which a dye that absorbs at least excitation light is mixed in plastic is used as the absorption means 9, for example, when blue light is used as the excitation light, a yellow filter can be used as the absorption means 9.

  Further, the diffusing means 19 may be anything that can diffuse the excitation light, and there are two cases, that is, when an additional member such as a white resin is used and when a diffusible fine structure is provided on the surface of the light reflective substrate 6. Can be broadly divided. When using an additional member such as a white resin, it is further divided into a method of dispersing a white powder in a transparent resin and a case of using a white plate-like ceramic not containing a resin component. In the case of a method of dispersing white powder in a transparent resin, a silicone resin or the like can be used as the transparent resin. Further, as the white powder, ceramic powder such as aluminum oxide, zirconium oxide, and magnesium oxide can be used. In the production method, first, a resin and white powder are kneaded, arranged around the phosphor layer 2 on the light-reflective substrate 6 by using a method such as printing or dispensing, and cured as it is in a curing furnace. In this way, a configuration as shown in FIGS. 7A and 7B can be realized. If a concave portion is provided in the light reflective substrate 6 first, the configuration as shown in FIGS. 8A and 8B can be realized by the same method. Furthermore, a configuration as shown in FIGS. 9A and 9B covering a part of the upper surface of the phosphor layer 2 can be realized. Moreover, when using the white plate-shaped ceramics which do not contain a resin component for the spreading | diffusion means 19, a white plate-shaped ceramics can be produced in the procedure similar to fluorescent substance ceramics. The difference from phosphor ceramics is that no luminescent center ions are included in the material and that the pores are left to be baked in order to have diffusibility. The finished plate-like ceramic may be finished into an arbitrary shape by cutting and polishing, and may be attached to the light reflective substrate 6 using a resin or an adhesive. Further, when the diffusing means 19 is configured by providing a diffusive fine structure on the surface of the light reflective substrate 6, the fine structure provided on the light reflective substrate 6 is only required to diffuse excitation light, and the shape and the like are particularly limited. Not. For example, the fine structure provided on the light reflective substrate 6 may be provided as a precise periodic structure by etching, or may be provided by polishing using abrasive grains. If the light-reflective substrate 6 is a metal substrate, a concave portion is produced by electric discharge machining, so that the bottom surface is finished in a rough shape as shown in FIGS. 10 (a) and 10 (b). it can.

  Next, the light source device of the present invention will be described in more detail.

  In the light source device of the present invention, the solid-state light source 5 can be a light emitting diode or a semiconductor laser having an emission wavelength in the range from ultraviolet light to visible light.

More specifically, the solid-state light source 5 may be, for example, a light emitting diode or semiconductor laser that emits near-ultraviolet light having an emission wavelength of about 380 nm to about 400 nm using an InGaN-based material. In this case, the phosphor of the phosphor layer 2 is excited by ultraviolet light having a wavelength of about 380 nm to about 400 nm. For example, a red phosphor is CaAlSiN ₃ : Eu ²⁺ , (Ca, Sr) AlSiN. ₃ : Eu ²⁺ , Ca ₂ Si ₅ N ₈ : Eu ²⁺ , (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ , KSiF ₆ : Mn ⁴⁺ , KTiF ₆ : Mn ^{4+ and the} like are used as the yellow phosphor. , (Sr, Ba) ₂ SiO ₄ : Eu ²⁺ , Ca _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu ^{2+ and the} like are used, and (Ba, Sr) ₂ SiO ₄ : Eu ²⁺ , Ba ₃ Si ₆ O ₁₂ N ₂ : Eu ²⁺ , (Si, Al) ₆ (O, N) ₈ : Eu ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ^{2+ and the} like are used, and blue BaMgAl ₁₀ O ₁₇ : Eu ²⁺ or the like can be used as the color phosphor.

The solid-state light source 5 may be, for example, a light emitting diode or semiconductor laser that emits blue light having a light emission wavelength of about 460 nm using a GaN-based material. In this case, as the phosphor of the phosphor layer 2, as the wavelength is excited by the blue light of about 440nm to about 470 nm, for example, the red ^{_{phosphor, CaAlSiN 3: Eu 2+, (}} Ca, Sr) AlSiN ₃ : Eu ²⁺ , Ca ₂ Si ₅ N ₈ : Eu ²⁺ , (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ , KSiF ₆ : Mn ⁴⁺ , KTiF ₆ : Mn ^{4+ and the} like are used as the yellow phosphor. Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Sr, Ba) ₂ SiO ₄ : Eu ²⁺ , Ca _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu ^2+, etc. ^{_{, Lu 3 Al 5 O 12:}} Ce 3+, (Lu, Y) 3 Al 5 O 12: Ce 3+, Y 3 (Ga, Al) 5 O 12: Ce 3+, Ca 3 Sc 2 Si 3 O 12: _{^{e 3+, CaSc 2 O 4:}} Eu 2+, (Ba, Sr) 2 SiO 4: Eu 2+, Ba 3 Si 6 O 12 N 2: Eu 2+, (Si, Al) 6 (O, N) 8: Eu 2+ Etc. can be used.

As the phosphor layer 2, a phosphor in which these phosphor powders are dispersed in glass, a glass phosphor in which a luminescent center ion is added to a glass matrix, a phosphor ceramic not including a binding member such as a resin, or the like is used. Can do. As a specific example of the phosphor powder dispersed in glass, the phosphor powder having the composition listed above is contained in a glass containing components such as P ₂ O ₃ , SiO ₂ , B ₂ O ₃ , and Al ₂ O _3. Are dispersed. Examples of glass phosphors in which a luminescent center ion is added to a glass matrix include Ca—Si—Al—O—N and Y—Si—Al—O—N systems in which Ce ³⁺ or Eu ²⁺ is added as an activator. Examples thereof include oxynitride glass phosphors. Examples of the phosphor ceramic include a sintered body having a phosphor composition having the composition listed above and substantially not including a resin component. Among these, it is desirable to use a phosphor ceramic having translucency. This is a phosphor ceramic that has translucency because there are almost no pores or impurities at grain boundaries that cause light scattering in the sintered body. Since pores and impurities can also prevent thermal diffusion, translucent ceramics exhibit high thermal conductivity. For this reason, when it uses as a fluorescent substance layer, it can take out from a fluorescent substance layer, and can utilize it, without losing excitation light and fluorescence by diffusion, Furthermore, the heat | fever which generate | occur | produced in the fluorescent substance layer can be dissipated efficiently. Even a sintered body that does not show translucency is desirable to have as few pores and impurities as possible. As an index for evaluating the remaining amount of pores, the value of specific gravity of the phosphor ceramic can be used, and it is desirable that the value is 95% or more with respect to the theoretical value by which the value is calculated.

Here, a method for producing a phosphor ceramic having translucency will be described by taking as an example a Y ₃ Al ₅ O ₁₂ : Ce ³⁺ phosphor that is a yellow-excited phosphor emitting blue light. The phosphor ceramic is manufactured through a starting material mixing step, a forming step, a firing step, and a processing step. As starting materials, yttrium oxide, cerium oxide, alumina, and the like, oxides of constituent elements of Y ₃ Al ₅ O ₁₂ : Ce ³⁺ phosphor, carbonates, nitrates, sulfates and the like that become oxides after firing are used. The particle size of the starting material is preferably a submicron size. These raw materials are weighed so as to have a stoichiometric ratio. At this time, for the purpose of improving the transmittance of the ceramic after firing, it is also possible to add a compound such as calcium or silicon. The weighed raw materials are sufficiently dispersed and mixed by a wet ball mill using water or an organic solvent. Next, the mixture is formed into a predetermined shape. As the molding method, a uniaxial pressing method, a cold isostatic pressing method, a slip casting method, an injection molding method, or the like can be used. The obtained molded body is fired at 1600 to 1800 ° C. Thus, translucent ^{_{Y 3 Al 5 O 12: Ce}} 3+ phosphor ceramic can be obtained.

  The phosphor ceramic produced as described above is polished to a thickness of several tens to several hundreds of μm using an automatic polishing apparatus and the like, and is further rounded by dicing or scribing using a diamond cutter or laser. Cut out to a board of any shape such as a square, fan or ring.

  Here, phosphor ceramics have a high refractive index with respect to air, and there are few things that cause scattering such as pores inside, and light is guided inside the ceramics. The light emission component emitted from the side surface increases, and the light emission component emitted in the front direction decreases. In order to solve this problem, the light emission component emitted in the front direction can be increased by providing an uneven light extraction structure by etching on the ceramic surface, mounting a lens, or providing a reflective layer on the side surface. Is also possible.

  The light-reflective substrate 6 can be a metal substrate, oxide ceramics, non-oxidized ceramics, etc., but it is desirable to use a metal substrate having particularly high light reflection characteristics, heat transfer characteristics, and workability. . As the metal, simple substances such as Al, Cu, Ti, Si, Ag, Au, Ni, Mo, W, Fe, and Pd and alloys containing them can be used. The surface of the light reflective substrate 6 may be coated for the purpose of increasing reflection and preventing corrosion. Further, the substrate 6 may be provided with a structure such as a fin in order to improve heat dissipation.

  In addition, a resin, an organic adhesive, an inorganic adhesive, a low-melting glass, brazing, or the like can be used for the joint 7 between the phosphor layer 2 and the light reflective substrate 6. Among these, in order to make use of the reflectance of the light reflective substrate 6, it is desirable to use a resin or an inorganic adhesive having a high excitation light transmittance for the joint portion 7. When using these, it can adhere | attach by apply | coating resin or an inorganic adhesive agent on the light-reflective board | substrate 6, arrange | positioning the fluorescent substance layer 2 on it, and heating in a curing furnace. Also, brazing is desirable when it is desired to improve heat dissipation. The ceramic and metal can be joined by first forming a metal film on the ceramic side and brazing the metal film and the metal substrate. The metal film can be formed on the ceramic by a vacuum deposition method, a sputtering method, a refractory metal method, or the like. The refractory metal method is a method in which an organic binder containing metal fine particles is applied to the surface of a ceramic and heated to 1000 to 1700 ° C. in a reducing atmosphere containing water vapor and hydrogen. For the metal film formed at this time, a simple substance or an alloy containing Si, Nb, Ti, Zr, Mo, Ni, Mn, W, Fe, Pt, Al, Au, Pd, Ta, Cu, or the like is used. As the brazing material, a brazing material containing Ag, Cu, Zn, Ni, Sn, Ti, Mn, In, Bi, or the like can be used. If necessary, the oxide film on the joining surface of the metal film and the metal can be removed by flux, a brazing material is placed on the joining surface, heated to 200 to 800 ° C., and cooled to be joined. Moreover, in order to prevent destruction of the joint surface due to the difference in the thermal expansion coefficient between the ceramic and the metal after joining, the joining may be performed by interposing a substance having an intermediate thermal expansion coefficient between the ceramic and the metal.

  In addition, by combining the above-described light source device of the present invention with a predetermined lens system, a mirror, a reflector, or the like, it is possible to achieve a sufficiently high brightness as compared with the prior art, and the illumination light can be colored. A lighting device with almost no unevenness can be provided.

  The present invention can be used for automotive lighting such as headlamps, projectors, and general lighting.

2 Phosphor Layer 5 Solid Light Source 6 Light Reflective Substrate 9 Absorbing Means 19 Diffusing Means 10, 20 Light Source Device

Claims (3)

A solid-state light source that emits light of a predetermined wavelength in a wavelength region from ultraviolet light to visible light, and at least emits fluorescence having a wavelength longer than the emission wavelength of the solid-state light source when excited by excitation light from the solid-state light source A phosphor layer including one type of phosphor, and a light reflective substrate provided on a surface of the phosphor layer opposite to a surface on which excitation light is incident, the solid-state light source, A reflection-type light source device that is spatially separated from the phosphor layer, the shape of the beam of the excitation light from the solid light source incident on the phosphor layer on the phosphor layer incident surface; A light source device characterized in that a cross-sectional area is substantially equal to the shape and area of the entire phosphor layer incident surface. 2. The light source device according to claim 1, wherein an absorption means for absorbing the excitation light or a diffusion means for diffusing the excitation light is provided around the phosphor layer when the excitation light from the solid light source is incident. A light source device. An illumination device using the light source device according to claim 1.

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