JP2011243840A - Light source device and luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device which uses a phosphor layer having a solid light source emitting blue light and a β sialon phosphor and which can restrain variation of output (light emission intensity) even when the wavelength of the solid light source emitting blue light is in the wavelength range of 460 nm to 490 nm.SOLUTION: A light source device comprises: a solid light source 5 to emit blue light; a phosphor layer 2 containing at least one kind of phosphor, which is excited by the blue light from the solid light source 5 and which emits phosphor light of the wavelength longer than the wavelength of the blue light from the solid light source 5. The phosphor layer 2 contains as a phosphor emitting green light a β sialon phosphor with at least Yb (ytterbium) activated.

Description

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

  Light source device combining a solid state light source such as a light emitting diode and a phosphor layer (light emitted from the solid state light source (excitation light) is excited by being incident on the phosphor layer and has a wavelength longer than the wavelength of the light from the solid state light source) The light source device of the type that emits the fluorescent light from the phosphor layer has been widely used. In recent years, the brightness has been increased, and its application range has been expanded to light sources for general lighting and displays, automobile headlamps, and the like. ing. Such a light source device is considered to be widely used for various purposes in the future.

  In order to increase the brightness of a light source device combining such a solid light source and a phosphor layer, it is conceivable to increase the excitation light intensity by supplying a large current, but in reality, heat is generated in the phosphor layer. Since the fluorescence intensity is lowered due to the temperature quenching of the phosphor, the emission intensity is saturated and reduced as a result, and it is difficult to increase the luminance of the illumination light.

  Here, 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. Thus, the temperature quenching of the phosphor generated by heat has also been a factor that hinders the increase in luminance.

  As a solution to this problem, for example, as shown in Patent Document 1, a light source device in which a phosphor layer is formed on a color wheel (hereinafter referred to as a fluorescence rotator) that can rotate around a rotation axis can be cited. It is done. FIG. 1 is a schematic view of a light source device using a fluorescent rotator. In FIG. 1, reference numeral 95 denotes a solid light source, and reference numeral 91 denotes a fluorescent rotator. In the light source device of FIG. 1, the fluorescent rotator 91 is configured as a transmission type and excited by excitation light from the solid light source 95. Of the emitted light from the phosphor layer, light (transmitted light) emitted to the side opposite to the solid light source 95 side is used (hereinafter, this type of fluorescent rotator is referred to as transmissive fluorescent rotation). Called the body).

  When a fluorescent rotator is used, the phosphor layer is rotating even when irradiated with high-power excitation light, and the time during which the same part is excited is short, so heat generation is suppressed and the light is in a different location. The heat is dissipated while hitting. Therefore, since it is possible to suppress a large amount of heat from being locally generated by the excitation light irradiation in the phosphor layer, it is possible to suppress discoloration of the resin component and temperature quenching of the phosphor, thereby achieving high brightness. It becomes possible.

  By the way, as a light source device combining a solid light source and a phosphor layer (for example, a light source device for a display such as a liquid crystal display or a projector), it is desired not only to increase the brightness but also to expand the color reproduction range of the display. It is rare. In order to expand the color reproduction range, it is necessary that each of the R (red), G (green), and B (blue) components of the emission spectrum of the light source has a spectrum with a narrow half-value width.

  Considering a solution to this problem for a light source device in which a solid light source and a phosphor layer are combined, it is necessary to use a phosphor having an emission spectrum with a narrow half width at the phosphor layer. Paying particular attention to green phosphors, β sialon phosphors activated by Eu (europium) ions reported in Patent Document 2 are widely known as phosphors having an emission spectrum with a narrow half-value width. This phosphor can be excited by ultraviolet light to blue light, exhibits green light emission with an emission wavelength of 540 nm, and has a narrow half-value width of the emission spectrum. Therefore, when combined with a solid-state light source, this phosphor has an emission spectrum with high brightness and a narrow half-value width. A light source device can be realized.

Special table 2009-539219 JP 2008-120938 A

  In order to realize a light source device that has a light emission device that combines a solid light source and a phosphor as described above and has an emission spectrum with a higher luminance and a narrow half-value width, Eu-activated β sialon is used as the phosphor (green phosphor). It is necessary to devise measures to suppress the heat generation of the phosphor more than ever before by using the phosphor.

  Here, when the heat generation from the phosphor is examined in detail, the heat generation is divided into a component caused by an energy difference between excitation light and fluorescence called Stokes shift and a component caused by energy that has not been converted into fluorescence. The former takes a constant value regardless of the temperature, and the latter increases as the temperature increases. Therefore, although the latter component can be reduced by suppressing the temperature rise of the phosphor, another device is required for the former component. Since the component resulting from the Stokes shift is determined by the energy difference between the excitation light and the fluorescence, heat generation can be reduced by reducing this energy difference. Specifically, by exciting the phosphor with longer wavelength light (excitation light) without changing the emission wavelength of the phosphor, the energy difference between the excitation light and the fluorescence is reduced, and heat generation from the phosphor is reduced. Can be reduced. Of course, the same effect can be achieved even if the fluorescent wavelength of the phosphor is shortened. However, changing the fluorescent wavelength changes the emission color, which may adversely affect the color reproduction range and is not desirable. Accordingly, a blue light emitting solid-state light source having a light emission peak of 440 nm to 460 nm is usually used. However, in order to reduce the heat generation due to the Stokes shift of the phosphor, the wavelength is longer than 440 nm to 460 nm. It is desirable to use a solid light source having an emission wavelength of 460 nm or more.

  From the above, the light source device combining the solid-state light source having an emission wavelength longer than 460 nm longer than that conventionally used and the Eu-activated β-sialon phosphor has a high emission luminance and a narrow half-value width emission spectrum. However, as a result of actually examining this light source device, the inventors of the present application have found a new problem (problem) that has not been known so far.

  That is, in a light source device that combines a solid-state light source having an emission wavelength longer than 460 nm and a Eu-activated β sialon phosphor that has a longer emission wavelength than that conventionally used, the initial output of the light source device varies greatly, or There is a problem that the output fluctuates with the change of the temperature of the solid light source during driving. Such variations in output and fluctuations during driving greatly impair the value of the product due to problems that lead to increased costs, such as a non-defective product selection process and the addition of a temperature control mechanism.

  As a result of examining the cause of the above problem (problem), the inventor of the present application has found that this cause exists in both the solid light source and the phosphor.

  That is, first, solid-state light sources that emit blue light, both light-emitting diodes and semiconductor lasers, are manufactured with a target emission wavelength, and the emission wavelength actually emitted from the solid-state light source varies from the target value by about 5 nm. is there. This variation is caused by film formation non-uniformity. In addition to this initial variation, when the temperature of the solid light source rises during driving, a phenomenon in which the emission wavelength generally shifts to a longer wavelength occurs. The amount of movement depends on the structure of the element, but it is also known that the amount of movement is about 5 nm. Thus, the emission wavelength of the solid-state light source is accompanied by initial variations and fluctuations during driving.

  Next, as for phosphors, β-sialon phosphors are generally well-known that activate Eu ions, but as shown in FIG. 2, the excitation spectrum of Eu-activated β-sialon phosphors is visible from the ultraviolet region. Over the optical region, particularly in the wavelength region of 400 nm or more, it has a downward-sloping structure. Accordingly, since the excitation spectrum is further inclined in the wavelength range of 460 nm to 490 nm, which is longer than the light in the wavelength range of 440 nm to 460 nm, which is usually used as blue light, the temperature changes in the wavelength range of 460 nm to 490 nm. When the excitation wavelength varies due to the above, the fluorescence intensity (green light emission intensity) also varies greatly.

  Thus, the variation and fluctuation of the emission wavelength of the solid-state light source that emits blue light, and 460 nm, which is longer than the light in the wavelength range of 440 nm to 460 nm that is used as the normal blue light of the solid-state light source that further emits blue light. In the wavelength range of ˜490 nm, the fluorescence intensity of the Eu-activated β sialon phosphor largely fluctuates due to a slight change in the excitation wavelength. As a result, the output (light emission intensity) as the light source device varies greatly and fluctuates. I found out.

  The present invention relates to a light source device and an illumination device using a solid light source that emits blue light and a phosphor layer having a β sialon phosphor, in order to reduce the half width of the emission spectrum and reduce heat generation (high brightness Even when the wavelength of a solid light source emitting blue light is set to a wavelength range of 460 nm to 490 nm, which is longer than the wavelength range of 440 nm to 460 nm, which is normally used as blue light, the output (emission intensity) It is an object of the present invention to provide a light source device and an illumination device capable of suppressing fluctuations in

  In order to achieve the above object, the invention described in claim 1 includes a solid-state light source that emits blue light, and fluorescence that is excited by blue light from the solid-state light source and has a longer wavelength than the wavelength of blue light from the solid-state light source. A phosphor layer containing at least one kind of phosphor that emits light, and the phosphor layer contains at least a β-sialon phosphor activated with Yb, A light source device.

  The invention according to claim 2 includes a solid light source that emits blue light and a fluorescent rotator that can rotate around a rotation axis, and the fluorescent rotator is excited by the blue light from the solid light source. The light source device includes a phosphor layer including a β sialon phosphor that activates at least Yb that emits fluorescence having a wavelength longer than the wavelength of blue light from the solid-state light source.

  According to a third aspect of the present invention, in the light source device according to the first or second aspect, the solid-state light source is a light emitting diode or a semiconductor laser.

  According to a fourth aspect of the present invention, in the light source device according to any one of the first to third aspects, the solid-state light source has an emission wavelength in a range of 460 nm to 490 nm. Yes.

  The invention according to claim 5 is the light source device according to any one of claims 1 to 4, wherein the β sialon phosphor activated with at least Yb contains both lanthanoids other than Yb and Yb. It is characterized by being a β sialon phosphor activated as a luminescent center ion.

  The invention according to claim 6 is the light source device according to claim 5, characterized in that the lanthanoid other than Yb is Eu.

  The invention according to claim 7 is an illumination device characterized by using the light source device according to any one of claims 1 to 6.

  According to invention of Claim 1, Claim 3 thru | or 7, The solid-state light source which light-emits blue light, A wavelength longer than the wavelength of the blue light excited by the blue light from this solid-state light source, and this solid-state light source And a phosphor layer containing at least one kind of phosphor that emits the fluorescence, and the phosphor layer contains a β sialon phosphor that activates at least Yb. In order to reduce heat generation (in order to increase the brightness), the wavelength of a solid light source that emits blue light is longer than the wavelength range of 440 nm to 460 nm that is normally used as blue light. Even when the wavelength range is 490 nm, the fluctuation in output (light emission intensity) can be suppressed for green light emission (the fluctuation in output (light emission intensity) is small with respect to the wavelength fluctuation of the solid light source due to temperature change or the like). ) Light source device and illumination device can be provided.

  According to the second to seventh aspects of the present invention, the solid-state light source that emits blue light and the fluorescent rotator that can rotate around the rotation axis are provided. A phosphor layer containing at least Yb-activated β sialon phosphor that is excited by blue light and emits fluorescence having a wavelength longer than the wavelength of blue light from the solid-state light source. The wavelength range of the solid light source emitting blue light is smaller than the wavelength range of 440 nm to 460 nm, which is usually used as blue light, in order to further reduce the heat generation (in order to further increase the brightness) However, even when the wavelength is in the long wavelength range of 460 nm to 490 nm, it is possible to suppress fluctuations in output (light emission intensity) (changes in output (light emission intensity) with respect to wavelength fluctuations of the solid light source due to temperature changes, etc.). It is possible to provide a smaller) light source device and a lighting device.

It is the schematic of the light source device using a fluorescence rotary body. It is a figure which shows the excitation spectrum of Eu activated beta sialon fluorescent substance. It is a figure (schematic diagram) showing the example of composition of the light source device of a 1st embodiment of the present invention. It is a figure which shows the example of 1 structure of the light source device of the 2nd Embodiment of this invention. It is a figure (plan view) which shows various structural examples about the case where the fluorescent substance layer of the reflection type fluorescent rotating body is divided into a plurality of sections. It is a figure (plan view) which shows various structural examples about the case where the fluorescent substance layer of the reflection type fluorescent rotating body is divided into a plurality of sections. It is a figure (plan view) which shows various structural examples about the case where the fluorescent substance layer of the reflection type fluorescent rotating body is divided into a plurality of sections. It is a figure (sectional drawing) which shows the example which has arrange | positioned two types of fluorescent substance layers so that it may overlap | superpose in the perpendicular direction. It is a figure which shows the quantity of each material about each of Example 1, Example 2, and a comparative example. For each of Example 1, Example 2, and Comparative Example, β sialon phosphors (Si ₆ Al _6-z O _z N _8-z : A (A is light emission) when the materials are blended in the amounts shown in FIG. It is a figure which shows the composition of z of a center ion, 0 <z <= 4.2)), A (Yb), and A (Eu). It is a figure which shows the emission spectrum of each beta sialon fluorescent substance of Example 1, Example 2, and a comparative example. It is a figure which shows the excitation spectrum of each (beta) sialon fluorescent substance of Example 1, Example 2, and a comparative example. It is a figure which shows the value (intensity) of the excitation spectrum in the wavelength range of 460 nm-490 nm about each beta sialon fluorescent substance of Example 1, Example 2, and a comparative example.

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

  FIG. 3 is a diagram (schematic diagram) illustrating a configuration example of the light source device according to the first embodiment of the present invention. Referring to FIG. 3, the light source device 10 includes a solid-state light source 5 that emits blue light and fluorescent light that is excited by blue light from the solid-state light source 5 and has a wavelength longer than that of the blue light from the solid-state light source 5. A phosphor layer 2 containing at least one kind of phosphor that emits light, and the phosphor layer 2 includes a phosphor in which a β sialon phosphor activated with at least Yb (ytterbium) emits green light (hereinafter referred to as “green phosphor”). It is characterized by being included as a green phosphor).

  Here, a light-emitting diode or a semiconductor laser is used as the solid-state light source 5 that emits blue light, and the solid-state light source 5 has a wavelength longer than 460 nm that is longer than the wavelength range of 440 nm to 460 nm that is normally used as blue light. What emits light is used. As a result, the heat generation due to the Stokes shift of the phosphor can be reduced, and the temperature quenching of the phosphor can be reduced, and as a result, the brightness of the light source device can be increased. Considering only the decrease in heat generation caused by the Stokes shift, the longer the emission wavelength, the better. However, the β sialon phosphor has a lower fluorescence intensity when the excitation wavelength is longer than 490 nm. Is preferably in the wavelength range of 460 nm to 490 nm.

  In addition, as described above, the inventor of the present application has a wavelength of 440 nm to 460 nm that is normally used as blue light of a solid light source that emits blue light. In the wavelength range of 460 nm to 490 nm, which has a longer wavelength than the light in the range, the fluorescence intensity of the Eu-activated β sialon phosphor largely fluctuates due to a slight change in the excitation wavelength, resulting in an output as a light source device ( It has been found that the light emission intensity) also varies widely and fluctuates. In order to solve this problem, the inventor of the present application has considered using a β sialon phosphor having an excitation spectrum with a small value fluctuation in a range of 460 nm or more. It was not done.

  As will be described later, the inventor of the present application conducted a firing experiment of β sialon phosphors activated with Yb ions, and based on the experimental results, Yb ions were used as luminescent center ions to activate β sialon phosphors. It was found that the fluctuation of the value of the excitation spectrum is smaller in the wavelength range of 460 nm to 490 nm than the β sialon phosphor activated only by Eu (europium). It has been clarified by the inventor of the present application that this effect can be obtained when only Yb is activated or when Yb is activated simultaneously with Eu. In this way, the inventors of the present application newly realize that the phosphor layer 2 in which the fluctuation of the excitation spectrum value is small in the wavelength range of 460 nm to 490 nm can be realized by activating the Yb ions to the β sialon phosphor. It was found. In addition, although the β sialon phosphor (green light emitting phosphor) in which Yb ions are activated as the emission center is described in the above-mentioned Patent Document 2, nothing has been known about its specific characteristics. No (nothing reported).

  As described above, according to the light source device 10 of the first embodiment of the present invention, the solid-state light source 5 that emits blue light and the blue light that is excited by the blue light from the solid-state light source 5 A phosphor layer 2 containing at least one kind of phosphor that emits fluorescence having a wavelength longer than the wavelength, and the phosphor layer 2 has a β-sialon phosphor activated with at least Yb (ytterbium) in green. Since it is included as a phosphor, the half-value width of the emission spectrum is narrow, and the wavelength of the solid light source 5 that emits blue light is used as normal blue light in order to reduce heat generation (in order to increase brightness). Even when the wavelength range of 460 nm to 490 nm is longer than the wavelength range of 440 nm to 460 nm, fluctuations in output (fluorescence (green light) emission intensity) of green light emission can be suppressed (warm With respect to the wavelength variation of the solid-state light source due to the change or the like, output small variation in (fluorescence intensity) of) it is possible to provide a light source device.

  In the configuration example of FIG. 3, the mixed light of the light emitted from the solid light source 5 (blue light) and the fluorescence emitted from the phosphor layer 2 (green light) is used, but the mixed light is converted into monochromatic light through a filter. It may be used (only green light may be taken out) or may be used as it is as mixed light. In particular, when a phosphor emitting from orange to red is used as the phosphor layer 2 together with a β sialon phosphor (green phosphor) activated with Yb ions (when mixed), It is also possible to use a mixture of phosphors that emit yellow light), and to obtain white light. Thus, the β sialon phosphor (green phosphor) activated with Yb ions and the phosphor emitting longer wavelength fluorescence can be mixed in the same phosphor layer 2 and used.

  FIGS. 4A and 4B are diagrams showing a configuration example of the light source device according to the second embodiment of the present invention. 4A is a front view of the whole, and FIG. 4B is a plan view of the fluorescent rotator. Further, in FIGS. 4A and 4B, portions corresponding to those in FIG. Referring to FIGS. 4A and 4B, the light source device 20 can be rotated around the rotation axis X by being driven by a solid-state light source 5 that emits blue light and a drive unit (not shown) such as a motor. The fluorescent rotator 1 is excited by blue light (excitation light) from the solid light source 5 and emits fluorescence having a wavelength longer than that of the blue light from the solid light source 5. It has a phosphor layer 2 containing at least β sialon phosphor (green phosphor) activated with Yb.

  In the light source device 20 of the second embodiment having such a configuration, the phosphor layer 2 contains at least β sialon phosphor (green phosphor) activated with Yb, so that the first embodiment In the same manner as described in, the half-width of the emission spectrum is narrow, and the wavelength of a solid-state light source that emits blue light is usually used as blue light in order to reduce heat generation (in order to increase the luminance). Even when the wavelength range of 460 nm to 490 nm is longer than the wavelength range of ˜460 nm, it is possible to suppress fluctuations in output (fluorescence (green light) emission intensity) of green light emission (solid due to temperature change, etc.) It is possible to provide a light source device in which the output (fluorescence (green light) emission intensity) is small in variation with respect to the wavelength variation of the light source.

  Furthermore, in the light source device 20 of the second embodiment, by using the fluorescent rotator 1, the phosphor layer 2 is rotated even when irradiated with high-power excitation light, and the same part is excited. Is short, so heat generation is suppressed and the heat is dissipated while the light strikes another location. Therefore, since it is possible to suppress the generation of a large amount of heat locally due to the excitation light irradiation in the phosphor layer 2, it is possible to suppress discoloration of the resin component and temperature quenching of the phosphor, thereby achieving high luminance. Is possible.

  Further, in the light source device 20 of FIGS. 4A and 4B, the fluorescent rotator 1 has light reflectivity on the surface of the phosphor layer 2 opposite to the side on which the excitation light is incident, for example. A substrate 6 is provided. In this case, the substrate 6 is formed of a light reflective material (for example, metal). The substrate 6 also has a function as a heat dissipation substrate. That is, the substrate 6 also serves as a reflection surface for fluorescence and excitation light, serves to dissipate heat from the phosphor layer 2 to the outside, and serves as a support substrate for the phosphor layer 2. For this reason, high light reflection characteristics, heat transfer characteristics, and workability are required. The substrate 6 can be a metal substrate, oxide ceramics such as alumina, or non-oxide ceramics such as aluminum nitride, but a metal substrate having particularly high light reflection characteristics, heat transfer characteristics, and workability is used. Is desirable. In this way, by forming the substrate 6 with a light-reflective material (for example, metal), the fluorescent rotator 1 is made to fluoresce from the surface of the phosphor layer 2 where the excitation light is incident. In addition, it can be configured as a reflection type fluorescent rotating body that extracts excitation light by reflection.

  Here, the reflection type fluorescent rotator will be described. In the light source device shown in FIG. 1, among the emitted light from the phosphor layer 92 excited by the excitation light from the solid light source 95, the fluorescence emitted to the opposite side to the solid light source 95 side and the phosphor layer 92 are absorbed. The excitation light of the solid light source 95 that is transmitted without being used. That is, the fluorescent rotator 91 is used as a transmission type fluorescent rotator. In this transmissive fluorescent rotator 91, the light emitted from the phosphor layer 92 is reflected at the interface with the phosphor layer 92 together with the transmitted light and returns to the solid light source 95 side, that is, reflected light. Therefore, this reflected light becomes light that cannot be used as illumination light. Further, in the transmission type fluorescent rotating body 91, it is necessary to increase the thickness of the phosphor layer 92 in order to obtain illumination light having a target chromaticity, which is disadvantageous in dissipating heat.

  On the other hand, in the light source device 20 of FIGS. 4A and 4B, among the emitted light from the phosphor layer 2 excited by the excitation light from the solid light source 5, the fluorescence emitted to the solid light source 5 side Excitation light from the solid light source 5 reflected by the phosphor layer 2 is used. That is, the fluorescent rotator 1 is used as a reflection type fluorescent rotator. By using the reflection type fluorescent rotating body in this way, reflected light of excitation light can also be used as illumination light, so that it is possible to further increase the brightness. In contrast to the transmission type, the reflection type allows the phosphor layer to be made thinner because the optical path lengths in the phosphor layer are equal and light of the same chromaticity can be obtained even when the thickness of the phosphor layer is less than half. Since the distance from the layer 2 to the substrate 6 is shortened, it is advantageous in terms of heat dissipation.

  In this way, by making the fluorescent rotator 1 a reflective fluorescent rotator, it is possible to further increase the luminance. In each of the following examples, description will be made assuming that the fluorescent rotator 1 is a reflection type fluorescent rotator.

  4 (a) and 4 (b), the phosphor layer 2 has a phosphor dispersed in a resin, a phosphor dispersed in glass, or a binder component. Phosphor ceramics that do not contain can be used. The phosphor ceramic is a lump of phosphor that is formed by firing a material into an arbitrary shape before firing in the manufacturing process of the phosphor. The 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 forming a degreasing process after the molding, the phosphor ceramic after firing has a binder component of 5 wt%. Only the following remains: Since glass and ceramics made of only inorganic substances generally have higher thermal conductivity than resin, they are 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.

  The phosphor layer 2 and the substrate 6 are bonded to each other in the case of a phosphor layer in which the phosphor is dispersed in a resin or glass. Organic adhesives, inorganic adhesives, low melting glass, metal brazing, and the like can be used as bonding agents.

  4 (a) and 4 (b), for example, use a mixed light of emission (blue light) of the solid light source 5 and fluorescence (green light) emitted from the phosphor layer 2. In this case, the mixed light may be used as monochromatic light through a filter (only green light may be taken out) or may be used as it is as mixed light. In particular, when a phosphor emitting from orange to red is used as the phosphor layer 2 together with a β sialon phosphor (green phosphor) activated with Yb ions (when mixed), It is also possible to use a mixture of phosphors that emit yellow light), and to obtain white light. In this way, β sialon phosphor (green phosphor) activated with Yb ions and phosphor emitting longer wavelength fluorescence may be mixed in the same phosphor layer 2 and used as follows. In this manner, separate phosphor layers may be formed and used.

  That is, in the example of FIGS. 4A and 4B, only one type of phosphor layer is used as the phosphor layer 2 of the fluorescence rotator 1. Specifically, in the example of FIGS. 4A and 4B, only the phosphor layer made of, for example, a green phosphor is used as the phosphor layer 2 of the phosphor rotator 1 (in this case, as the solid light source 5). If a material that emits blue light is used, illumination light in which green light and blue light are mixed can be obtained as reflected light), green, red, and even phosphors can be uniform, for example. (In this case, if a solid light source that emits blue light is used, illumination light such as white light can be obtained as reflected light.) it can). However, the present invention is not limited to this, and various modifications are possible. That is, the phosphor layer 2 of the fluorescent rotator 1 can be configured such that at least one phosphor layer of green, red, yellow or the like is disposed. In other words, the phosphor layer 2 of the fluorescence rotator 1 may be divided into a plurality of sections. When divided into a plurality of sections, it is desirable to separate adjacent sections with a light-reflective separation wall in order to prevent light emission from mixing with the adjacent sections. Further, the type of phosphors dispersed in each section and the amount of dispersion (concentration) may be different. Moreover, the thickness of the phosphor layer in each section may be different.

  5, 6, and 7 are diagrams (plan views) illustrating various configuration examples when the phosphor layer 2 of the reflection type fluorescent rotator 1 is divided into a plurality of sections. 5, 6, and 7 are illustrated in correspondence with the configuration of FIG. 4A and FIG. 4B (the phosphor layer 2 of the reflection type fluorescent rotating body 1) for convenience of explanation. In the example of FIG. 5, two types of phosphor layers 2 a and 2 b (for example, a phosphor layer 2 a made of a red phosphor and a phosphor layer 2 b made of a green phosphor) are used as the phosphor layer 2 of the reflection type fluorescent rotator 1. Is provided as a phosphor region divided into two equal parts. In this case, if a solid-state light source that emits blue light is used, white or the like is reflected as the reflected light when the reflective fluorescent rotator 1 is rotated. Illumination light can be obtained. In the example of FIG. 6, two types of phosphor layers 2 a and 2 b (for example, a phosphor layer 2 a made of a red phosphor and a phosphor layer made of a green phosphor are used as the phosphor layer 2 of the reflective phosphor rotator 1. 2b) is provided as a phosphor region, and a region where no phosphor layer is provided is provided as a non-phosphor region 42c. In this case, if a solid light source that emits blue light is used, a reflective type is used. Illumination light such as white light can be obtained as reflected light when the fluorescent rotator 1 rotates. In the example of FIG. 7, as the fluorescent layer 2 of the reflection type fluorescent rotator 1, three types of fluorescent layers 2a, 2b, 2c (for example, a fluorescent layer 2a made of a red fluorescent material and a fluorescent light made of a green fluorescent material). The body layer 2b and the phosphor layer 2c made of a yellow phosphor are provided as the phosphor region, and the region where the phosphor layer is not provided is provided as the non-phosphor region 42c. If one that emits blue light is used, illumination light such as white can be obtained as reflected light when the reflective fluorescent rotator 1 rotates.

  Thus, when the fluorescent substance layer 2 of the fluorescent rotating body 1 is divided into a plurality of sections, the arrangement of the fluorescent substance layer 2 is shown in FIGS. 5 and 5 when two or more kinds of fluorescent substance layers are used. 6. These phosphor layers can be arranged in the horizontal direction as shown in FIG. Alternatively, two or more types of phosphor layers can be stacked in the vertical direction. FIG. 8 shows a fluorescent rotating body 1 in which, for example, two types of phosphor layers 2a and 2b (for example, a phosphor layer 2a made of a red phosphor and a phosphor layer 2b made of a green phosphor) are vertically stacked. An example is shown in cross section. In the case of the configuration of FIG. 8 as well, if a solid light source that emits blue light is used, illumination light such as white can be obtained as reflected light when the fluorescent rotator 1 rotates.

  Hereinafter, the light source devices 10 and 20 of the first and second embodiments of the present invention will be described in more detail.

First, a β sialon phosphor activated with Yb (ytterbium) (hereinafter referred to as a Yb activated β sialon phosphor) will be described. The β sialon phosphor is represented by the composition formula Si ₆ Al _{6 -z} O _z N _{8 -z} : A (A is an emission center ion, 0 <z ≦ 4.2), and has the same crystal structure as β-type silicon nitride. It has. By activating the β sialon phosphor with the Yb ion as the luminescent center ion, the variation of the excitation spectrum value is smaller in the wavelength range of 460 nm to 490 nm than the β sialon phosphor activated only with Eu. A phosphor can be obtained. This effect can be obtained when only Yb is activated or when other lanthanoids such as Eu and Ce are simultaneously activated as luminescent center ions. The combined concentration of Yb ions and other emission center ions at this time is preferably in the range of 0.05 mol% to 1.0 mol% with respect to the number of moles of the base material. This is because when the emission center ion concentration is 0.05 mol% or less, the fluorescence intensity is not sufficiently obtained because the emission center ion is too low, and when the emission center ion concentration is 1.0 mol% or more, concentration quenching occurs, resulting in fluorescence intensity. This is because sufficient cannot be obtained. On the other hand, when the amount of Yb ions is too small, the value of the excitation spectrum of the β sialon phosphor fluctuates downward in the wavelength range of 460 nm to 490 nm, which is not desirable. As for the particle diameter of the phosphor, the median diameter is desirably in the range of 10 μm to 30 μm. This is because the emission efficiency of the phosphor is low when the median diameter is less than 10 μm, and when the median diameter is larger than 30 μm, it is difficult to uniformly disperse within the phosphor layer.

  The method for producing the Yb-activated β sialon phosphor is as follows. Prepare Si (silicon), Al (aluminum), Yb (ytterbium) as a starting material, and nitride, oxide or fluoride powders of lanthanoid elements other than Yb to be used as the luminescent center ion, and achieve the desired composition ratio Weigh and mix well. Mixing can be performed with a ball mill using balls made of alumina or silicon nitride, and wet mixing using ethanol, isopropanol, hexane, or the like as a solvent may be performed to increase mixing efficiency. However, since the material may react with moisture in the solvent, the solvent is preferably dehydrated. After mixing, it is sufficiently dried in a vacuum drying furnace or a drying furnace in a nitrogen atmosphere. Then, if necessary, it is classified to the desired size through a mesh and put into a boron nitride crucible. The material is fired at 1800 to 2000 ° C. for 2 to 10 hours in a nitrogen pressurized atmosphere of 0.1 to 1.0 MPa. After calcination, in order to remove impurities, it may be washed with an acidic solution such as hydrochloric acid or hydrofluoric acid, an alkaline solution such as sodium hydroxide, or boiled water. Finally, the target phosphor powder can be obtained by classification through the mesh once more. In addition, it is also possible to obtain a plate-like phosphor ceramic by molding a material using a slip casting method or a pressure molding method before firing and performing firing.

  Further, as the solid light source 5, a light emitting diode or laser diode having a light emission wavelength in the blue light region can be used, and a light source having a light emission wavelength of 460 nm or more is particularly desirable. In the present invention, when a light source having high excitation light intensity is used, the effect appears remarkably. Therefore, the present invention is not limited to these light sources, but for example, a blue color of about 480 nm using a GaN-based material. A laser diode that emits light can be used.

In addition to the Yb-activated β sialon phosphor, the phosphor used in the phosphor layer 2 absorbs light in the blue light region and emits light having a longer wavelength than the Yb-activated β sialon phosphor. Things can be used. For example, for red, 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 can be used. For yellow, use 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. Can do.

As the phosphor layer 2, those obtained by dispersing these phosphor powders in a resin or glass, or phosphor ceramics can be used. As the resin, a thermosetting resin such as a silicone resin, a silicon epoxy resin, or a fluororesin, or a thermoplastic resin such as a liquid crystal polymer can be used. Here, as the _{glass, SiO 2, B 2 O 3} , Al 2 O, a low melting point glass containing a component such as P 2 _{O 5} and the like in the composition.

  Further, the phosphor can be made into a phosphor ceramic by molding and firing before firing. Phosphor ceramics are polished to a thickness of several tens to several hundreds of μm using an automatic polishing machine, etc., and further shaped in any shape such as a circle, square, fan, or ring by dicing or scribing using a diamond cutter or laser. Can be made of It is also possible to provide an uneven light extraction structure by etching or opportunity polishing on the surface of the phosphor ceramic, to mount a lens, or to increase the emission component emitted in the front direction.

  The substrate 6 can be a metal substrate, oxide ceramic, non-oxide ceramic, or the like, 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 these substrates 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, the phosphor layer 2 and the substrate 6 can be bonded to each other as long as the phosphor layer 2 is made of resin or glass. In the case of ceramics, organic adhesives, inorganic adhesives, low melting glass, brazing, and the like can be used. In particular, brazing that can achieve both high reflectivity and heat transfer characteristics is desirable. That is, 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. Here, 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. In addition, a brazing material containing Ag, Cu, Zn, Ni, Sn, Ti, Mn, In, Bi, or the like can be used as the brazing material. 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 expansion coefficient between the ceramic and the metal after joining, the joining may be performed by interposing a substance having an intermediate expansion coefficient between the ceramic and the metal.

  Moreover, the fluorescent rotator 1 can be realized by connecting the phosphor layer 2 and the substrate 6 joined to a motor or the like. The shape of the substrate 6 at this time may be a disk shape or a quadrangle. Moreover, in order to ensure the stability of rotation, it is also possible to cut out a part of the disk or to have a shape with a weight on the contrary.

  In each of the above examples, the substrate 6 is made of metal or the like, and the fluorescent rotator 1 is made as a reflective fluorescent rotator. However, if the substrate 6 is made of a light-transmitting material (transparent material), The fluorescent rotator 1 can also be configured as a transmission type fluorescent rotator as shown in FIG. Also in this case, by applying the present invention (that is, the fluorescent rotator 1 is excited by the blue light from the solid light source 5 and emits fluorescence having a wavelength longer than that of the blue light from the solid light source 5). In order to reduce the half-value width of the emission spectrum and further reduce the heat generation (by further increasing the brightness), the phosphor layer 2 containing the β sialon phosphor activated with Yb is included. The output (emission intensity) is also obtained when the wavelength of the solid light source 5 emitting blue light is set to a wavelength range of 460 nm to 490 nm, which is longer than the wavelength range of 440 nm to 460 nm, which is normally used as blue light. Can be suppressed (the fluctuation of the output (light emission intensity) is small with respect to the fluctuation of the wavelength of the solid light source due to a temperature change or the like).

  Although not shown in the above examples, an optical element such as a lens may be provided between the solid light source 5 and the phosphor layer 2 if necessary.

  In addition, by combining the above-described various light source devices of the present invention with optical components such as a predetermined lens system, the half-value width of the emission spectrum is narrow and the heat generation is further reduced (with higher brightness). Output (emission intensity) even when the wavelength of the solid-state light source 5 emitting blue light is set to a wavelength range of 460 nm to 490 nm, which is longer than the wavelength range of 440 nm to 460 nm, which is normally used as blue light. ) Can be suppressed (the output (light emission intensity) fluctuation is small relative to the wavelength fluctuation of the solid-state light source due to a temperature change or the like).

  Finally, a firing experiment of the Yb-activated β sialon phosphor made by the inventors of the present application will be described.

First, α-type silicon nitride (Si ₃ N ₄ : Ube Industries SN-E10), aluminum nitride (AlN: Tokuyama H grade), aluminum oxide (Al ₂ O ₃ : Sumitomo Chemical APK-Y300), Ytterbium oxide (Yb ₂ O ₃ : Shin-Etsu Chemical purity 99.99%) and europium oxide (Eu ₂ O ₃ : Shin-Etsu Chemical purity 99.99%) were prepared. Examples 1, 2 and Comparative Examples For each, these materials are blended in the amounts shown in FIG. 9 (in FIG. 9,% is weight percent of the total material) and β-sialon phosphor (Si ₆ Al _6-z O _z N _8-z : A (A is (Emission center ion, 0 <z ≦ 4.2)) z, A (Yb), and A (Eu) are set to have the composition shown in FIG. In example 2, Y And the Eu equal amounts activated and activated only Eu in the comparative example). In FIG. 10, “%” is a mole percent with respect to the number of moles of the base material.

  These materials were sufficiently mixed by a ball mill using silicon nitride balls. The mixed material was classified through No. 100 nylon mesh and then put into a boron nitride crucible. This crucible was placed in a multi-purpose firing furnace (High Multi 5000 manufactured by Fuji Denpa) and baked at 2000 ° C. for 4 hours in a nitrogen 1.0 MPa atmosphere. The obtained fired product was unraveled in a mortar, washed with boiling hot water, dried and classified through a # 380 nylon mesh. The phosphor thus obtained was examined with a powder X-ray diffractometer (D8 Advance manufactured by Bruker AXS). As a result, it was confirmed that the structures of Example 1, Example 2, and Comparative Example all had a β sialon structure.

  Furthermore, the result of having measured the emission spectrum and the excitation spectrum using the fluorescence spectrophotometer (F4500 by Hitachi, Ltd.) is shown in FIG. 11 and FIG. In addition, FIG. 11, FIG. 12 is shown by the relative value normalized by the maximum value. From FIGS. 11A and 11B, the emission spectra of Examples 1, 2 and Comparative Examples are all in the vicinity of 540 nm and do not change. However, when the excitation spectra of FIG. 12 are compared, Example 1 and Example 2 in which Yb is activated are compared. The excitation spectrum in the wavelength range of 460 nm to 490 nm has a relatively small change in value (intensity), whereas in the comparative example in which only Eu is activated, the intensity of the excitation spectrum greatly decreases as the wavelength becomes longer in the same range. is doing. For easier understanding, FIG. 13 shows the value (intensity) of the excitation spectrum re-normalized with the value of 460 nm. As shown in the lower part of FIG. 13, the amount of change (intensity) of the excitation spectrum in the wavelength range of 460 nm to 490 nm ((maximum value) − (minimum value) of the excitation spectrum in the wavelength range of 460 nm to 490 nm) In the comparative example in which only Eu is activated, it is as large as 23.2%, whereas in Example 1 in which only Yb is activated, 16.5%, Yb and Eu are activated in equal amounts. In Example 2, significant improvement of 11.6% was confirmed.

  The Yb-activated β sialon phosphor thus obtained is combined with a solid-state light source 5 having an emission wavelength of 460 nm or more to obtain a light source device using the reflection type fluorescent rotator 1, thereby achieving high brightness and a narrow half-value width ( It is possible to realize a light source device that has good color purity) and little variation and fluctuation in green light output.

  The present invention can be used for general lighting, displays, automobile headlamps, and the like.

DESCRIPTION OF SYMBOLS 1 Fluorescence rotating body 2 Phosphor layer 42c Non-phosphor area | region 5 Solid light source 6 Substrate 10, 20 Light source device

Claims (7)

A solid-state light source that emits blue light, and a phosphor layer that includes at least one phosphor that is excited by blue light from the solid-state light source and emits fluorescence having a wavelength longer than the wavelength of the blue light from the solid-state light source. And the phosphor layer contains at least a β sialon phosphor activated with Yb. A solid-state light source that emits blue light; and a fluorescent rotator that is rotatable around a rotation axis. The fluorescent rotator is excited by blue light from the solid-state light source, and has a wavelength of blue light from the solid-state light source. A light source device characterized by having a phosphor layer containing at least Yb-activated β sialon phosphor that emits long-wavelength fluorescence. 3. The light source device according to claim 1, wherein the solid state light source is a light emitting diode or a semiconductor laser. 4. The light source device according to claim 1, wherein the solid-state light source has an emission wavelength in a range of 460 nm to 490 nm. 5. The light source device according to claim 1, wherein the β sialon phosphor activated with at least Yb is β sialon fluorescence activated with both lanthanoids other than Yb and Yb as luminescent center ions. A light source device characterized by being a body. 6. The light source device according to claim 5, wherein the lanthanoid other than Yb is Eu. An illumination device using the light source device according to any one of claims 1 to 7.

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