JP5071937B2 - Lighting device - Google Patents

Description

  The present invention relates to an illumination device, and more particularly to an illumination device using a semiconductor laser as a light source.

  The illumination device is classified into a dot shape, a line shape, and a surface shape according to the shape of the light source. Examples of light sources used for general illumination include incandescent bulbs and fluorescent lamps. An incandescent lamp is a light source that obtains visible light by flowing current through a filament in a vacuum glass bulb filled with argon gas or the like and emitting heat from the incandescent filament. A fluorescent lamp is a light source that fills mercury vapor in a low-pressure glass tube, and converts the ultraviolet rays obtained by thermionic electrons from the electrode filament to mercury atoms to the phosphor applied on the inner surface of the fluorescent tube to convert it into visible light. It is.

  In recent years, interest in energy saving and the environment has increased, and the light source used in the lighting device is also shifting from an incandescent bulb to a light source with low power consumption such as a fluorescent lamp. In recent years, light emitting diodes (hereinafter referred to as LEDs: Light Emitting Diodes) are also attracting attention as light sources for lighting devices due to their increased luminous efficiency and low power consumption. A white LED used as a light source for illumination is a combination of an LED that emits blue light and a phosphor such as YAG (Yttrium Aluminum Garnet) that absorbs blue light and emits yellow fluorescence, or an LED that emits ultraviolet light. And a phosphor that absorbs ultraviolet light and emits visible fluorescence (for example, red, green, and blue).

  In order to realize a linear or planar illumination device using LEDs, there are a method of arranging a plurality of white LEDs in a linear or planar manner, a method of using a light guide, and the like. In the method using a light guide, LED light is coupled to a fiber-shaped or plate-shaped light guide, and the light guide is made to contain a phosphor that converts LED light into white light. A lighting device can be realized.

  Further, a white illumination device using a GaN-based semiconductor laser (hereinafter, LD: Laser Diode) as a light source is also disclosed (for example, see Patent Document 1). Patent Document 1 proposes an illumination light source device that obtains illumination light by exciting a phosphor with laser light from a semiconductor laser.

  In addition, the semiconductor laser has a feature that the output light is narrowed down and has strong directivity. By utilizing this feature, a semiconductor laser is coupled to an optical fiber, and a fluorescent material is provided around the cladding of the optical fiber to obtain a line light source. For example, Patent Document 2 proposes an example of a light emitting device using a linear or fiber light guide structure.

In the linear light guide structure disclosed in Patent Document 2, a clad layer is formed so as to include a central core portion concentrically, and the periphery thereof is covered with a concentric covering portion. The fluorescent material is dispersed in the covering portion. When a semiconductor laser element connected to one end face of such an optical fiber is energized, the fluorescent material in the coating is excited by the laser light introduced into the fiber, and the fluorescent material is emitted into the space. Is done.
JP-A-7-282609 JP 2002-148442 A

  Incandescent bulbs lose most of their electrical energy as heat and part of it is emitted as light, resulting in poor luminous efficiency and high power consumption. In addition, the light sources for linear and planar illumination devices require uniform light emission, but incandescent bulbs are point light sources and are not suitable for linear and planar illumination devices. On the other hand, fluorescent lamps have problems such as using harmful mercury, emitting ultraviolet rays, and being difficult to downsize.

  Linear and planar illumination devices using LEDs can be realized by arranging LEDs. However, since the intensity of light per LED is weak, it is necessary to arrange a very large number of LEDs. Therefore, if the characteristics are different for each LED element, the control circuit becomes complicated, and it becomes difficult to uniformly emit light on the entire line or surface. Further, in a planar or linear illumination device using an LED and a light guide, the light output of the LED is small, and it is difficult to extract uniformly strong illumination light.

  Further, in the illumination device in which the LD and the optical fiber described in Patent Document 2 are combined, a light output larger than that of the LED can be put into the fiber by using the LD, but the phosphor is caused by the light leaking from the optical fiber. Therefore, the light extraction efficiency is poor and strong illumination light cannot be extracted. Further, even if the leakage light from the optical fiber is designed to be large and the strong illumination light is taken out, it is difficult to take out the uniform strong linear illumination light because the laser light is attenuated in the fiber.

  Moreover, in the conventional illumination light source device described in Patent Document 1, the light extraction efficiency is low, and a linear or planar light source cannot be obtained.

  The present invention has been made in view of the above problems, and a main object thereof is to provide a linear or planar illumination device with low power consumption, high light extraction efficiency, and uniform radiation. .

An illumination device according to the present invention includes a semiconductor laser element, a parallel light generation unit, a reflection unit, a fluorescence unit, and an optical system . The parallel light generator converts laser light generated from the semiconductor laser element into substantially parallel light. The reflection unit has a movable mechanism, and reflects the laser light transmitted through the parallel light generation unit. The fluorescent part includes a phosphor. The laser beam reflected by the reflecting portion, Ru is converted into fluorescence excited by irradiation to the phosphor. The optical system projects fluorescence in one direction. By moving the reflecting portion by the movable mechanism, the laser beam reflected by the reflecting portion is scanned. The phosphor is arranged on the locus of laser light that scans the fluorescent part.

  Here, the laser light oscillated from the semiconductor laser element and transmitted through the parallel light generation unit is most preferable if all the light is parallel and directed in the same direction and does not diffuse. However, if the width of the laser beam that scans the fluorescent part is sufficiently small and does not affect the light intensity of the linear illumination device, the laser beam that has passed through the parallel light generating part is completely parallel. Not necessarily. That is, the substantially parallel light includes the case where all of the laser light transmitted through the parallel light generation unit is parallel, and the laser light transmitted through the parallel light generation unit is not completely parallel but close to parallel. Including cases.

  Preferably, in the above-described illumination device, the fluorescent part includes a fluorescent plate in which a fluorescent material is encapsulated in a linear shape. The reflection unit includes a rotary mirror that is rotatably provided. The rotating mirror is installed so as to scan the laser beam by rotation and irradiate the phosphor encapsulated in a linear shape with the laser beam.

  Preferably, the fluorescent part includes a fluorescent plate in which a fluorescent material is enclosed. The fluorescence obtained by converting the laser light by the phosphor is emitted from the irradiated surface on the side on which the fluorescent light is irradiated with the laser light.

Preferably, a reflecting plate is provided on the side opposite to the irradiated surface with respect to the fluorescent plate.
Preferably, the illuminating device further includes a laser light cutting unit that is provided on the irradiated surface side with respect to the fluorescent plate and suppresses the laser light reflected from the irradiated surface and emitted to the outside of the illuminating device. The laser light cut portion may include an antireflection film that is formed on the irradiated surface and prevents reflection of light having the wavelength of the laser light on the irradiated surface. Further, the laser light cut section may include a filter that is provided apart from the irradiated surface and blocks light having a wavelength of the laser light.

  Preferably, the fluorescent part includes a fluorescent plate in which a fluorescent material is enclosed. The fluorescence obtained by converting the laser light by the phosphor is emitted from both the irradiated surface on the side where the fluorescent plate is irradiated with the laser light and the back surface opposite to the irradiated surface.

  Preferably, a part of the laser light directly irradiated on the fluorescent part from the reflecting part is reflected by the fluorescent part. The laser light reflected by the fluorescent part is irradiated again on the fluorescent part and converted into fluorescent light.

  Preferably, the wavelength of the laser light oscillated by the semiconductor laser element is not less than 400 nm and not more than 450 nm.

  According to this lighting device, a linear or planar lighting device capable of uniform radiation with low power consumption can be provided. That is, the laser light generated from the semiconductor laser element has the same wavelength, and can be made substantially parallel light by transmitting through the parallel light generation unit. By making the light substantially parallel, light is transmitted with the same intensity without loss up to a point away from the semiconductor laser element. By scanning the substantially parallel laser beam, a strong light intensity can be obtained at any point on the locus of the laser beam of the fluorescent part irradiated with the laser beam.

  By arranging the phosphor on the locus of the laser light in the fluorescent part, it is possible to easily realize a linear or planar illumination device capable of uniform emission and improved light emission uniformity. Since it is not necessary to arrange a large number of light sources and an illuminating device can be realized with a small number of light sources, the luminous efficiency is high, the power consumption of the illuminating device can be reduced, the circuit can be simplified and the cost can be reduced. By deforming the fluorescent part, lighting devices having various shapes can be easily realized.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  In the embodiments described below, each component is not necessarily essential for the present invention unless otherwise specified. In the following embodiments, when referring to the number, amount, etc., unless otherwise specified, the above number is an example, and the scope of the present invention is not necessarily limited to the number, amount, etc.

(Embodiment 1)
FIG. 1 is a perspective view illustrating a configuration of the lighting apparatus according to the first embodiment. 2 is a three-view diagram of the lighting device according to the first embodiment shown in FIG. 1. FIG. 2 (a) is a plan view of the lighting device, FIG. 2 (b) is a front view of the lighting device, and FIG. ) Shows a left side view of the lighting device. In FIG. 1 and FIG. 2, the inside of the housing is seen through for easy understanding. The illumination device of Embodiment 1 is a linear illumination device that transmits white light through a fluorescent plate.

  As shown in FIGS. 1 and 2, the illumination device according to the present embodiment includes an LD 100 as a semiconductor laser element. The LD 100 is a nitride semiconductor laser element. When current is injected, laser oscillation occurs and laser light is emitted. The active layer of the LD 100 is composed of an InGaN / GaN multiple quantum well and has an oscillation wavelength of 405 nm. The illuminating device also includes a lens 101 as a parallel light generation unit that converts laser light oscillated from the LD 100 into parallel light. The lens 101 is a collimating lens.

  The illumination device also includes a reflection unit that reflects the laser light. The reflecting portion includes a hexagonal column-shaped rotating mirror 111. A rotating mirror 111 as a rotating mirror provided so as to be rotatable is a hexagonal column rotating body, and six sides are mirrors. The lighting device also includes a fluorescent part containing a phosphor. The fluorescent part includes a fluorescent plate 103. The phosphor is encapsulated linearly in the phosphor plate 103. All of the configurations of the lighting devices described above are arranged inside the housing 104.

  The locus 105 of the laser light oscillated from the LD 100 will be described. As described above, the laser light is generated by injecting a current into the LD 100 and is converted into parallel light by the lens 101. The laser beam that has passed through the lens 101 reaches the rotating mirror 111 and is reflected by the reflecting surface 111a, which is one side surface of the rotating mirror 111, as indicated by a locus 105a. The reflected laser light is applied to the fluorescent plate 103 containing the phosphor as indicated by a locus 105b. The phosphor is excited by laser light and converts the laser light into fluorescence. This fluorescence is emitted forward (front side of the illumination device) as illumination light 106.

  Here, the rotating mirror 111 has a movable mechanism (not shown) such as a motor, and is rotated by the action of the movable mechanism. Therefore, the light reflected by the rotating mirror 111 vibrates linearly. The rotating mirror 111 is rotated by the movable mechanism, thereby scanning the laser beam reflected by the rotating mirror 111. The laser beam is scanned linearly by being reflected by the side surface of the polygonal column-shaped rotating mirror 111. The rotating mirror 111 is installed so as to scan the laser beam by rotation.

  The fluorescent plate 103 is installed so that the phosphor is arranged on a linear locus on which the laser light vibrates. The phosphor is disposed on the locus of laser light that scans the phosphor plate 103. A laser irradiation region 107 shown in FIGS. 1 and 2 indicates a region where the fluorescent plate 103 is irradiated with linearly scanned laser light. The laser beam reflected by the rotating mirror 111 is applied to the phosphor linearly enclosed in the phosphor plate 103, whereby the phosphor is excited, and the laser beam is converted into fluorescence by the phosphor. In this way, a linear light source is obtained. At this time, since the laser light is converted into parallel light by the lens 101, the laser light proceeds without being attenuated and is excited with the same laser light intensity at any position on the fluorescent plate 103. Therefore, uniform linear illumination light can be obtained on the fluorescent screen.

The phosphor excited by laser light uses an acrylic resin plate in which a phosphor emitting red light, a phosphor emitting green light, and a phosphor emitting blue light are mixed and dispersed. did. For example, Y ₂ O ₂ S: Eu ³⁺ is used as a phosphor that emits red light, and a phosphor that emits blue light, such as ZnS: Cu, Al, is used as a phosphor that emits green light. Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ : Eu ²⁺ ) or the like was used.

  The phosphor material is not limited to this, and may be any phosphor that is excited by light having the oscillation wavelength of laser light and emits red, blue, and green light. Oxynitride phosphors and nanoparticle phosphors can also be used. Further, the combination of the phosphors is not limited to the combination of red, blue and green, and white illumination light can be obtained by various combinations such as a combination of blue green and red and a combination of blue and yellow.

  Since the phosphor irradiated with the laser light does not emit light having an energy larger than the wavelength of the laser light, the wavelength of the laser light is desirably blue (450 nm) or less in order to obtain white illumination light. In addition, when the laser light is ultraviolet light, if a part of the laser light leaks out of the lighting device, the human body is irradiated with the ultraviolet light, and thus the wavelength of the laser light is preferably 400 nm or more. That is, the wavelength of the laser light oscillated by the LD 100 is preferably 400 nm or more and 450 nm or less.

  FIG. 3 is a schematic diagram for explaining the operation principle of the lighting apparatus of the first embodiment. FIG. 3 is a top view of the illumination device as in FIG. 2A, and FIGS. 3A, 3B, and 3C each show a rotating mirror 111 that is rotating in the direction of arrow R. It is a figure when it stops at the position. Specifically, FIG. 3A is a diagram when the laser beam reaches one end of the reflecting surface 111a, which is one surface of the hexagonal columnar rotating mirror 111. FIG. FIG. 3B is a diagram when the rotating mirror 111 is slightly rotated from the position of FIG. 3A and the laser beam is approaching the reflection surface 111a. FIG. 3C is a view when the laser beam is approached to the other end of the reflecting surface 111a of the rotating mirror 111 opposite to the one end.

  In FIG. 3A, the laser light reflected by the reflecting surface 111a is irradiated to the right end portion of the fluorescent plate 103 in the drawing as indicated by the locus 105b, and the phosphor at this position is excited and the illumination light 106 is emitted. . In FIG. 3 (b), the laser beam reflected by the reflecting surface 111a is irradiated to the position on the left side of the fluorescent plate 103 in the drawing as compared with FIG. 3 (a) as shown by the locus 105b, and from the phosphor at this position. Illumination light 106 is emitted. In FIG. 3C, the laser light reflected by the reflecting surface 111a is irradiated to the left end portion of the fluorescent plate 103 in the drawing as indicated by the locus 105b, and the phosphor at this position is excited and the illumination light 106 is emitted. .

  When the rotating mirror 111 further rotates in the direction of arrow R, the position where the laser beam is irradiated moves to the mirror on the side surface of the hexagonal column adjacent to the reflecting surface 111a, and becomes the position shown in FIG. Thus, by rotating the hexagonal column-shaped rotating mirror 111 at a high speed, the laser beam scans the fluorescent plate 103 linearly, and the linear illumination light 106 can be obtained from the fluorescent plate 103.

  As described above, in the illumination device according to the first embodiment, the laser light having a high intensity generated from the LD 100 has the same wavelength, and can be focused to parallel light by passing through the lens 101. By using parallel light, light is transmitted with the same intensity without loss to a point away from the LD. By scanning the parallel laser beam, a strong light intensity can be obtained at any point in the laser irradiation region 107 of the fluorescent plate 103. By arranging the phosphor on the laser irradiation region 107 and exciting the phosphor directly, it is possible to easily realize a linear illumination device capable of uniform emission and improved emission uniformity. There is no need to arrange a large number of light sources, and the lighting device can be realized with a small number of light sources, the luminous efficiency is high, the power consumption of the lighting device is reduced, the circuit is simplified, and the cost is reduced. Further, if the phosphor is sealed in the linear laser irradiation region 107, the laser light can be converted into fluorescence, so that the necessary amount of the phosphor can be reduced and a lower cost illumination device can be realized. As in the past, it is possible to take out the strong linear illumination light 106 without using the leakage light of the laser light, and the luminous efficiency of the illumination device is good.

  The lighting device includes a rotating mirror 111 that is rotatably provided. Since the laser beam is scanned by the rotation of the rotating mirror 111 and the phosphor is irradiated with the laser beam, the laser beam can be scanned with a simple structure to obtain a uniform linear illumination device.

(Embodiment 2)
FIG. 4 is a perspective view illustrating a configuration of the lighting apparatus according to the second embodiment. FIG. 5 is a three-view diagram of the lighting device according to the second embodiment shown in FIG. 4. FIG. 5 (a) is a plan view of the lighting device, FIG. 5 (b) is a front view of the lighting device, and FIG. ) Shows a left side view of the lighting device. In the first embodiment, the laser beam irradiated to the fluorescent plate 103 and transmitted through the fluorescent plate 103 is used as the illumination light 106, whereas in the second embodiment, the fluorescent plate 103 is used from the side where the laser beam is irradiated to the fluorescent plate 103. The difference from Embodiment 1 is that the reflected light is extracted and used as the illumination light 106.

  That is, the illumination device according to the second embodiment is a linear illumination device that emits white light from the side where the laser light is reflected by the fluorescent plate 103. Specifically, as illustrated in FIGS. 4 and 5, the illumination device of the second embodiment includes an octagonal prism-type rotating mirror 102. The rotating mirror 102 is an octagonal rotating body, and the eight sides are mirrors. The fluorescent plate 103 is provided on the front surface of the housing 104 in the first embodiment, whereas it is provided on the rear surface of the housing 104 in the second embodiment. Further, as shown in FIGS. 5B and 5C, the LD 100 and the lens 101 are installed below the fluorescent plate 103.

  The laser light oscillated from the LD 100 and passed through the lens 101 reaches the rotating mirror 102 and is reflected by one side of the rotating mirror 102 as indicated by a locus 105a. The reflected laser light is applied to the fluorescent plate 103 containing the phosphor as indicated by a locus 105b. The phosphor is excited by laser light, converts the laser light into fluorescence, and radiates it forward (to the irradiated surface 103a side where the laser light is irradiated on the fluorescent plate 103). The fluorescence obtained by converting the laser light by the phosphor is emitted from the irradiated surface 103a of the fluorescent plate 103, and the front 104a side (front side) opposite to the back surface 104b side (rear side) of the illumination device on which the fluorescent plate 103 is installed. Is emitted as illumination light 106 to the outside of the illumination device.

  The rotating mirror 102 vibrates the laser beam in a straight line like the rotating mirror 111 of the first embodiment. The laser beam is scanned linearly by being reflected by the side surface of the polygonal columnar rotary mirror 102. Since the rotating mirror 102 is formed in an octagonal prism shape, the frequency of the laser beam increases during one rotation of the rotating mirror 102 as compared with the first embodiment, and a uniform linear laser is generated by the fluorescent plate 103. Can irradiate light. In other words, in a rotating mirror formed in a polygonal column shape, the greater the number of polygon vertices that form the bottom and ceiling surfaces, the more the frequency of laser light can be increased during one rotation of the rotating mirror. Further, it is possible to improve the uniformity of the intensity of the laser beam applied to the fluorescent plate.

  The LD 100 and the lens 101 are installed below the fluorescent plate 103, and the laser beam is irradiated obliquely in the vertical direction. For this reason, it is possible to prevent the LD 100 and the like from being behind the illumination light 106 and hindering the light extraction from the illumination device to reduce the extraction efficiency.

  FIG. 6 is a schematic diagram for explaining the operating principle of the lighting apparatus according to the second embodiment. Similar to the illumination apparatus of the first embodiment described with reference to FIG. 3, the laser beam reflected by the reflecting surface 102a scans the fluorescent plate 103 linearly by rotating the octagonal prism-shaped rotating mirror 102 at high speed. (Scanning), and linear illumination light 106 can be obtained from the fluorescent plate 103. Note that a laser irradiation region 107 shown in FIG. 5B indicates a region irradiated with laser light from the fluorescent plate 103.

  As in the first embodiment, since the intense laser beam is focused into parallel light and the phosphor is directly excited, the illumination device has good light emission efficiency, and the strong linear illumination light 106 can be extracted. In the first embodiment, the illumination light 106 is extracted from the side opposite to the laser beam irradiation side of the fluorescent plate 103, whereas in the second embodiment, the illumination light 106 is input from the laser beam irradiation side (irradiated surface 103a side) of the fluorescent plate 103. Take out. As a result of comparison, it was found that the extraction efficiency of the illumination light 106 is higher when the illumination light 106 is extracted from the laser light irradiation side of the phosphor, and the strong illumination light 106 is obtained. Further, particularly intense illumination light 106 was emitted from the line scanned by the laser beam, and a strong and thin linear light source was obtained. Therefore, according to the illuminating device of Embodiment 2, a linear illuminating device with higher light intensity can be obtained.

(Embodiment 3)
FIG. 7 is a plan view of the lighting apparatus according to the third embodiment. The illumination device of the third embodiment is different from the second embodiment in that an antireflection film 108 is formed on the front side of the fluorescent plate 103 (the irradiated surface 103a side of the fluorescent plate 103 irradiated with laser light). Yes.

  When a semiconductor laser is used as a light source of an illuminating device, if the laser beam is emitted as it is to the outside of the illuminating device as it is, for example, if the laser beam enters the eye, the eyeball may be damaged. Therefore, it is desirable to prevent the laser light from being emitted outside the lighting device. In this embodiment, as a countermeasure, an antireflection film 108 is formed on the irradiated surface 103a to which the laser light of the fluorescent plate 103 is irradiated. The antireflection film 108 prevents reflection of light having the wavelength of the laser light on the irradiated surface 103a. The antireflection film 108 is provided on the irradiated surface 103a side of the fluorescent plate 103, and suppresses the laser light from being reflected by the irradiated surface 103a of the fluorescent plate 103 and being emitted to the outside of the illumination device.

The antireflection film 108 is realized by forming a thin film material of a single layer or two or more layers having different refractive indexes by, for example, vacuum deposition. When the thin film material is formed of two or more layers, it can be realized by a combination of a high refractive index material and a low refractive index material. For example, MgF ₂ or SiO ₂ can be used as the low refractive index thin film material. Further, as a high refractive index thin film _{material, ZrO 2, TiO 2, Ta} 2 O 5, Nb 2 O 5, etc. HfO ₂ can be used.

For example, as an example in which the antireflection film 108 is formed as a single layer, MgF ₂ is deposited on a fluorescent plate by depositing it to a thickness of 70 nm. As an example of forming two layers, TiO ₂ is formed by vapor deposition on a fluorescent plate in the order of 100 nm thickness and SiO ₂ thickness 90 nm. As an example of forming with three layers, Al ₂ O ₃ is deposited on a fluorescent plate in the order of 75 nm in thickness, ZrO ₂ in 125 nm in thickness, and MgF ₂ in 90 nm in order. The thin film material, the number of layers, and the layer thickness are not limited to these, and can be appropriately optimized and used by designing the reflectance to be low with respect to the wavelength of the semiconductor laser.

  FIG. 24 is a graph showing the reflectance of the fluorescent plate on which the antireflection film is formed. The horizontal axis in FIG. 24 indicates the wavelength (unit: nm) of light incident on the antireflection film 108. The vertical axis in FIG. 24 represents the reflectance (unit:%) for each wavelength of light incident on the fluorescent plate 103 on which the antireflection film 108 is formed. In FIG. 24, the value of the vertical axis of the corresponding reflectance graph when the horizontal axis is 405 nm is almost 0%. That is, it can be seen that the reflectance of the laser beam on the fluorescent plate 103 can be reduced with respect to the wavelength of 405 nm of the semiconductor laser.

  By using the antireflection film 108, it is possible to prevent the reflected light of the semiconductor laser from being emitted to the outside of the lighting device and to ensure the safety for the eyes. In other words, the antireflection film 108 functions as a laser light cut portion, so that a semiconductor laser illuminating device of a linear light source that is safe for eyes can be obtained. In addition, since the amount of laser light incident on the fluorescent plate 103 is increased by the amount of reflection, the laser light can be converted into fluorescence more effectively.

(Embodiment 4)
FIG. 8 is a plan view of the illumination device of the fourth embodiment. The illuminating device of Embodiment 4 is implemented in that a reflecting plate 109 is provided on the rear side of the fluorescent plate 103 (the back surface 103b side opposite to the irradiated surface 103a irradiated with the laser light of the fluorescent plate 103). Different from Form 2.

  In the present embodiment, a reflecting plate 109 is provided on the back surface 103b side with respect to the fluorescent plate 103, the laser light transmitted through the fluorescent plate 103 is reflected by the reflecting plate 109, and the phosphor encapsulated in the fluorescent plate 103 is excited. To do. Therefore, it was possible to extract more intense light than in the second embodiment.

(Embodiment 5)
FIG. 9 is a plan view of the lighting apparatus according to the fifth embodiment. In the illumination device of Embodiment 5, the fluorescence excited by the fluorescent material provided on the front surface 104a side opposite to the back surface 104b side of the housing 104 provided with the fluorescent plate 103 is radiated as illumination light 106 to the outside. The illumination light extraction window 115 is different from the second embodiment in that a filter 110 is provided.

  In this embodiment, a filter 110 that does not transmit light having a wavelength of laser light is provided in the illumination light extraction window 115 of the illumination device. The filter 110 is provided apart from the irradiated surface 103a of the fluorescent plate 103, and blocks light having the wavelength of the laser light. Since the wavelength of the wavelength of the semiconductor laser is extremely narrow, it is easy to block the light by the filter 110. Further, since the semiconductor laser uses light of 400 nm or more and 450 nm or less, even if the light of the semiconductor laser is cut off, the color and intensity as the illumination light 106 do not change.

The filter 110 is realized by forming two or more layers of thin film materials having different refractive indexes by, for example, vacuum deposition. As a thin film material, a high refractive index material and a low refractive index material are combined and laminated. For example, MgF ₂ or SiO ₂ can be used as the low refractive index thin film material. Further, as a high refractive index thin film _{material, ZrO 2, TiO 2, Ta} 2 O 5, Nb 2 O 5, etc. HfO ₂ can be used.

For example, SiO _{2 is formed} to a thickness of 30 nm, (TiO _{2 is formed} to a thickness of 35 nm, and SiO _{2 is formed} to a thickness of 60 nm) 10 times, and TiO _{2 is formed} to a thickness of 35 nm and SiO ₂ is formed to a thickness of 30 nm in this order. . The thin film material, the number of layers, and the layer thickness are not limited to these, and the transmittance should be designed to be low with respect to the wavelength of the semiconductor laser and high with respect to visible light of 450 nm to 700 nm. And are used by optimizing as appropriate.

  FIG. 25 is a graph showing the relationship between the wavelength of incident light to the filter and the transmittance with which the incident light passes through the filter. The horizontal axis of FIG. 25 indicates the wavelength (unit: nm) of light incident on the filter. The vertical axis in FIG. 25 indicates the transmittance (unit:%), which is the rate at which light passes through the filter with respect to the light of each wavelength incident on the filter. In FIG. 25, the value of the vertical axis of the corresponding transmittance graph when the horizontal axis is 405 nm is almost 0%. That is, it can be seen that the light does not pass through the filter for the wavelength of 405 nm of the semiconductor laser, and the laser light can be cut by the filter. In FIG. 25, the value on the vertical axis of the transmittance graph corresponding to a wavelength of 440 nm or more on the horizontal axis is almost 100%. That is, it can be seen that almost 100% of light passes through the filter for wavelengths of 440 nm or more used as illumination light.

  This filter 110 prevents the laser light from being reflected by the fluorescent plate 103 and emitted outside the illumination device, as in the third embodiment. The filter 110 suppresses the laser light from being reflected by the irradiated surface 103a of the fluorescent plate 103 and being emitted to the outside of the illumination device. The filter 110 functions as a laser light cut unit, so that a semiconductor laser illuminating device of a linear light source that is safe for eyes can be obtained.

(Embodiment 6)
FIG. 10 is a perspective view showing a configuration of the lighting apparatus of the sixth embodiment. FIG. 11 is a three-view diagram of the illumination device of the sixth embodiment shown in FIG. In the first embodiment, the laser light irradiated to the fluorescent plate 103 and transmitted through the fluorescent plate 103 is used as the illumination light 106, and in the second embodiment, the light reflected by the fluorescent plate 103 from the side on which the fluorescent plate 103 is irradiated. Is taken out and used as illumination light 106. On the other hand, the sixth embodiment is different from the first and second embodiments in that light is extracted from both sides of the fluorescent plate 103 and used as the illumination light 106.

  In other words, the illumination device of the sixth embodiment is configured such that the laser beam is reflected on the fluorescent plate 103 on both sides (that is, the irradiated surface 103a side where the laser beam is irradiated to the fluorescent plate 103 and the back surface 103b side opposite to the irradiated surface 103a It is a linear illumination device that emits white light from both sides. As shown in FIGS. 10 and 11, the illumination device of the sixth embodiment includes a cylindrical rotary mirror 113. The rotating mirror 113 is a right circular cylindrical rotating body, and the cylindrical surface of the side surface is a mirror, and the rotating shaft 114 is slightly tilted and rotated eccentrically from the cylindrical axis. As in the second embodiment, the fluorescent plate 103 is provided on the back surface of the housing 104, and the LD 100 and the lens 101 are installed below the fluorescent plate 103.

  The laser light oscillated from the LD 100 and passed through the lens 101 reaches the rotating mirror 113 and is reflected by one side of the rotating mirror 113 as indicated by a locus 105a. The reflected laser light is applied to the fluorescent plate 103 containing the phosphor as indicated by a locus 105b. The phosphor is excited by laser light. The fluorescence obtained by converting the laser light by the phosphor is emitted from both the front side (the irradiated surface 103a side on which the fluorescent plate 103 is irradiated with the laser light) and the rear side (the back surface 103b side opposite to the irradiated surface 103a side). The illumination light 106 is extracted outside the illumination device.

  Since the cylindrical rotating mirror 113 rotates about the rotating shaft 114 that is an eccentric tilt axis, the cylindrical rotating mirror 113 can be configured to vibrate the laser beam in a straight line. The laser beam is scanned linearly by being reflected by the side surface of a cylindrical rotary mirror 113 in which the rotary shaft 114 is eccentric and inclined.

  FIG. 12 is a schematic diagram for explaining the operating principle of the lighting apparatus according to the sixth embodiment. Similar to the illumination device of the first embodiment described with reference to FIG. 3, the laser beam reflected by the reflecting surface is reflected by the fluorescent plate 103 by rotating the cylindrical rotating mirror 113 around the eccentric tilt axis at a high speed. Can be linearly scanned (scanned) to obtain linear illumination light 106 from the fluorescent plate 103. In addition, the laser irradiation area | region 107 shown in FIG.11 (b) has shown the area | region where the laser beam of the fluorescent plate 103 was irradiated.

  As in the first embodiment, since the intense laser beam is focused into parallel light and the phosphor is directly excited, the illumination device has good light emission efficiency, and the strong linear illumination light 106 can be extracted. In this embodiment, since the illumination light 106 is extracted from both sides of the phosphor, the extraction efficiency of the illumination light 106 is improved.

(Embodiment 7)
FIG. 13 is a perspective view showing a configuration of the lighting apparatus of the seventh embodiment. FIG. 14 is a three-view diagram of the illumination device of the seventh embodiment shown in FIG. In the sixth embodiment, light is extracted from both sides of the fluorescent plate 103. On the other hand, in the present embodiment, the reflecting plate 116 is installed at the position where the illumination light extraction window 115 is formed in the sixth embodiment, and both the illumination light 106 extracted from both sides of the fluorescent plate 103 are received in the casing. The fourth embodiment is different from the sixth embodiment in that it is taken out from the side where the fluorescent plate 103 of 104 is provided. 13 and 14, the front side and the back side of the housing 104 are inverted with respect to FIGS. 10 and 11, and the rotating mirror 113 is arranged on the right side in FIG. 10. On the other hand, in FIG.

  The illumination light 106 reflected on the irradiated surface side where the laser light is irradiated onto the fluorescent plate 103 is reflected again by the reflective plate 116 provided on the opposite side of the fluorescent plate 103 of the illumination device, and the illumination light provided above and below the fluorescent plate 103. It is discharged out of the lighting device through the extraction window 115. As described above, the illumination light 106 transmitted through the fluorescent plate 103 and the illumination light 106 reflected by the irradiated surface can be extracted in the same direction, and the illumination light 106 generated by the fluorescent plate 103 can be extracted from the same direction without waste. As a result, luminous efficiency was further improved.

(Embodiment 8)
FIG. 15 is a perspective view showing a configuration of the lighting apparatus of the eighth embodiment. FIG. 16 is a three-view diagram of the illumination apparatus according to the eighth embodiment shown in FIG. In the seventh embodiment, the illumination light 106 radiated from both sides of the fluorescent plate 103 is extracted from the same side of the housing 104 using the reflection plate 116. In the present embodiment, the reflecting plate 116 according to the seventh embodiment is designed to have a curved surface, and the illumination light 106 radiated from both sides of the fluorescent plate 103 is more efficiently extracted as the illumination light 106 from one direction of the housing 104. ing.

  In the illumination device of the present embodiment, an antireflection film 108 is formed on the irradiated surface side of the fluorescent plate 103 as in the third embodiment. The antireflection film 108 prevents the laser light from being reflected by the fluorescent plate 103 and emitted as laser light to the outside of the illumination device, and ensures safety for the eyes.

  As in the seventh embodiment, the illumination light 106 transmitted through the fluorescent plate 103 and the illumination light 106 reflected by the irradiated surface can be extracted in the same direction. In addition, in the eighth embodiment, since the reflecting plate 117 is designed with a curved surface, the illumination light 106 generated by the fluorescent plate 103 can be extracted from the same direction without waste, and the luminous efficiency is further improved. In addition, the reflector 117 can be formed so that the shape when viewed from the side shown in FIG. 16C is a parabolic shape, and the fluorescent plate 103 can be disposed at the focal point of the parabolic shape. The illumination light 106 that is reflected by the light and emitted to the outside of the illumination device can be made parallel light, which is more preferable.

(Embodiment 9)
FIG. 17 is a perspective view showing a configuration of the lighting apparatus of the ninth embodiment. FIG. 18 is a three-view diagram of the illumination device of the ninth embodiment shown in FIG. In the present embodiment, light is extracted radially from both sides of the fluorescent plate 120.

  The illumination device according to the ninth embodiment includes a triangular prism-type rotating mirror 112. The rotating mirror 112 is a triangular prism rotating body, and the three side surfaces are mirrors. The laser beam reflected by one side of the rotating mirror 112 is irradiated on the fluorescent plate 120 containing the phosphor. The phosphor is excited by the laser light, and illuminates both sides of the laser beam reflected by the fluorescent plate 120 (that is, both sides on the irradiated surface side where the laser light is irradiated on the fluorescent plate 120 and the back surface side opposite to the irradiated surface). It is emitted as light 106.

  The illumination light 106 emitted from the irradiated surface side of the fluorescent plate 120 passes through the filter 123 installed around the fluorescent plate 120 and is emitted outside the illumination device. The filter 123 blocks light having the wavelength of the laser light. Since the semiconductor laser uses light of 400 nm or more and 450 nm or less, even if the light of the semiconductor laser is blocked, the color and intensity of the illumination light 106 do not change.

  Since the rotating mirror 112 is rotated by the action of the movable mechanism, the light reflected by the rotating mirror 112 is scanned linearly. By setting the fluorescent plate 120 so that the phosphor is arranged on a linear locus scanned with the laser light, the phosphor arranged in a line is excited and a linear light source is obtained. In the present embodiment, the fluorescent plate 120 is formed in a curved shape. For example, the fluorescent plate 120 can be formed in an elliptic cylindrical surface shape. The illumination light 106 is radiated radially from the phosphors arranged linearly on the curved fluorescent plate 120 to the outside of the illumination device.

  FIG. 19 is a schematic diagram for explaining the operating principle of the lighting apparatus of the ninth embodiment. By rotating the triangular prism-shaped rotating mirror 112 at a high speed, the laser light reflected by the reflecting surface 112 a scans the fluorescent plate 120 in a linear manner, and the linear illumination light 106 can be obtained from the fluorescent plate 120. . Note that a laser irradiation region 107 illustrated in FIG. 18B indicates a region irradiated with the laser light of the fluorescent plate 103.

  Since the rotating mirror 112 is formed in a triangular prism shape, the range of the emitted angle of the laser light reflected on a predetermined surface of the rotating mirror 112 can be increased, and the laser reflected on the reflecting surface 112a. The range scanned by light can be further expanded. That is, in the rotating mirror formed in a polygonal column shape, the smaller the number of vertices of the polygon that forms the bottom surface and the ceiling surface, the larger the scanning area of the laser beam during one rotation of the rotating mirror. By using the fluorescent plate 120 formed in a curved shape in accordance with the scanning region of the laser light, a planar light source with improved uniformity of emitted light intensity can be obtained.

  In the present embodiment, the fluorescent plate 120 is irradiated with laser light, and a part of the laser light is reflected by the fluorescent plate 120. The laser beam once reflected by the fluorescent plate 120 is applied to other regions of the fluorescent plate 120 as indicated by a trajectory 105c, and the laser light is further converted into fluorescence in the irradiated region. The primary reflected light (laser light directly irradiated from the rotating mirror 112 to the fluorescent plate 120 and reflected once by the fluorescent plate 120) has sufficient intensity to excite the phosphor, although the intensity as laser light is reduced. ing.

  By converting such primary reflected light into fluorescence and taking it out as illumination light 106, the conversion efficiency of laser light into illumination light 106 is improved, and at the same time, the intensity of laser light emitted outside the apparatus is moderately reduced. This improves the safety for the eyes. In the present embodiment, a filter 123 that does not transmit the wavelength of the laser beam is used to prevent the laser beam reflected by the phosphor from being emitted outside the illumination device, and further to ensure safety for the eyes. .

  Since the laser light is focused into parallel light and the phosphor is directly excited by the strong laser light, the luminous efficiency is high and the illumination light on a strong line can be extracted. In the present embodiment, since the illumination light is extracted from both sides of the phosphor, the extraction efficiency of the illumination light 106 is improved, and a semiconductor laser illumination device of a linear light source that is safe for eyes is obtained. Since the fluorescent plate 120 is deformed and formed into a curved surface shape, a curved surface lighting device can be easily realized.

(Embodiment 10)
FIG. 20 is a perspective view showing a configuration of the lighting apparatus according to the tenth embodiment. FIG. 21 is a plan view of the lighting apparatus according to the tenth embodiment shown in FIG. FIG. 22 is an exploded plan view of each constituent member of the tenth embodiment.

  The illumination device according to the tenth embodiment includes a cylindrical rotary mirror 119. The rotary mirror 119 is a right circular cylinder, and the circular top surface 119a is a mirror. In the rotating mirror 119, the central axis of the cylinder and the rotating shaft 114 are deviated. The rotating shaft 114 is eccentrically rotated with a slight inclination from the cylinder axis.

  The laser beam reflected by the top surface 119a of the rotating mirror 119 is irradiated onto the fluorescent plate 121 containing the phosphor. The phosphor is excited by the laser beam, and illuminates both sides of the laser beam reflected by the phosphor plate 121 (that is, both sides of the irradiated surface side where the laser beam is irradiated on the phosphor plate 121 and the back surface side opposite to the irradiated surface). It is emitted as light 106. The illumination light emitted from the irradiated surface side of the fluorescent plate 121 is reflected by the reflecting plate 118 and emitted upward as shown in FIG. In addition, the laser light reflected by the fluorescent plate 121 excites the phosphor enclosed in the fluorescent plate 122 formed in a part of the reflective plate 118, is converted into fluorescence, and is emitted to the outside of the illumination device as illumination light 106. .

  Since the cylindrical rotating mirror 119 rotates about the rotating shaft 114 that is an eccentric tilt axis, the laser beam is scanned in a circular shape. The laser beam is scanned circumferentially by being reflected by the top surface 119a of a cylindrical rotary mirror 119 in which the rotary shaft 114 is eccentric and inclined. By arranging the fluorescent plate 121 so that the phosphor is arranged on a circular locus scanned by the laser light, the phosphor arranged in a circle is excited by the irradiation of the laser light, and forms a line (circle). A light source is obtained. At this time, since the laser light is parallel light, it is excited with the same laser light intensity at any position on the fluorescent screen 121. Therefore, uniform thin linear circular illumination light can be obtained.

  FIG. 23 is a schematic diagram for explaining the operating principle of the lighting apparatus according to the tenth embodiment. FIGS. 23A, 23C, and 23E are views when the rotating mirror 119 rotating around the rotating shaft 114 is stopped at a predetermined position. For the sake of explanation, the reflector 118 is not shown. FIGS. 23B, 23D, and 23F are views of the illumination device as viewed from above when corresponding to FIGS. 23A, 23C, and 23E, respectively. In FIGS. 23B, 23D, and 23F, the rotating mirror 119 below the fluorescent screen 121 is indicated by a broken line.

  When the laser beam is reflected by the top surface 119a of the rotating mirror 119 at the position of the rotating mirror 119 shown in FIGS. 23A and 23B, the reflected laser beam is irradiated to the right end portion of the fluorescent plate 121 in the figure, and this position The phosphor is excited and irradiated with illumination light 106. In FIGS. 23C and 23D, the rotating mirror 119 is rotated a little, and the laser beam reflected by the top surface 119a of the rotating mirror 119 is applied to the front portion of the fluorescent screen 121 in the drawing. In FIGS. 23 (e) and 23 (f), the rotating mirror 119 further rotates, and the laser beam reflected by the top surface 119 a of the rotating mirror 119 is applied to the left end portion of the fluorescent screen 121 in the drawing.

  Thereafter, when the rotary mirror 119 further rotates, the position returns to the position shown in FIGS. Thus, by rotating the cylindrical rotating mirror 119 at a high speed, the laser light scans the fluorescent screen 121 in a circular shape, and the circular illumination light 106 can be obtained from the fluorescent screen 121. Note that a laser irradiation region 107 illustrated in FIG. 21B indicates a region irradiated with the laser light from the fluorescent plate 121.

  In the present embodiment, the fluorescent part includes a fluorescent plate 121 in which a fluorescent material is enclosed. The fluorescent part includes a fluorescent plate 122 in which a fluorescent material is enclosed, as another fluorescent plate irradiated with the laser light reflected by the fluorescent plate 121. A part of the laser light applied to the fluorescent screen 121 is reflected by the fluorescent screen 121. The laser beam once reflected by the fluorescent plate 121 is irradiated again to the fluorescent plate 122, and the laser beam is further converted into fluorescence by the fluorescent plate 122.

  The primary reflected light (laser light directly irradiated on the fluorescent plate 121 from the rotating mirror 119 and reflected once by the fluorescent plate 121) has a sufficient intensity to excite the phosphor, although the intensity as laser light is reduced. ing. By converting such primary reflected light into fluorescence and taking it out as illumination light 106, the conversion efficiency of laser light into illumination light 106 is improved, and at the same time, the intensity of laser light emitted outside the apparatus is moderately reduced. This improves the safety for the eyes.

  Since the laser light is focused into parallel light and the phosphor is directly excited by the strong laser light, the luminous efficiency is high and it is possible to extract strong circular illumination light. Moreover, in this Embodiment, since the illumination light was taken out from both sides of the fluorescent plate 121 and the illumination light was taken out in one direction using the reflection plate 118, the illumination light extraction efficiency was improved. Since the fluorescent plate 121 is deformed and formed into a curved surface shape, a curved surface lighting device can be easily realized.

  In the description so far, the example of the illumination device in which the reflection unit that reflects the laser light includes the rotating mirror has been described. However, the present invention is not limited to this configuration, and other optical members such as a prism are used. The reflection part may be provided, and the reflection part which scans a laser beam by reciprocating may be provided.

  Although the embodiments of the present invention have been described above, the configurations of the embodiments may be appropriately combined. In addition, it should be considered that the embodiment disclosed this time is illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a perspective view illustrating a configuration of a lighting device according to Embodiment 1. FIG. FIG. 3 is a three-view diagram of the lighting device according to the first embodiment. FIG. 4 is a schematic diagram for explaining an operation principle of the lighting apparatus according to the first embodiment. FIG. 6 is a perspective view illustrating a configuration of a lighting device according to a second embodiment. FIG. 6 is a three-view diagram of the lighting apparatus according to the second embodiment. FIG. 10 is a schematic diagram for explaining the operating principle of the illumination device according to the second embodiment. FIG. 10 is a plan view of a lighting device according to a third embodiment. FIG. 10 is a plan view of a lighting device according to a fourth embodiment. FIG. 10 is a plan view of a lighting device according to a fifth embodiment. FIG. 10 is a perspective view illustrating a configuration of a lighting device according to a sixth embodiment. FIG. 10 is a three-side view of the lighting apparatus according to the sixth embodiment. It is a schematic diagram for demonstrating the operation principle of the illuminating device of Embodiment 6. FIG. FIG. 38 is a perspective view illustrating a configuration of a lighting device according to a seventh embodiment. FIG. 12 is a three-side view of the lighting apparatus according to the seventh embodiment. FIG. 29 is a perspective view illustrating a configuration of a lighting device according to an eighth embodiment. FIG. 29 is a three-sided view of the lighting apparatus according to the eighth embodiment. FIG. 45 is a perspective view illustrating a configuration of a lighting device according to a ninth embodiment. FIG. 38 is a three-view drawing of the illumination device of the ninth embodiment. FIG. 38 is a schematic diagram for explaining an operation principle of the lighting apparatus according to the ninth embodiment. FIG. 38 is a perspective view illustrating a configuration of a lighting device according to a tenth embodiment. FIG. 38 is a plan view of the lighting device according to the tenth embodiment. FIG. 38 is an exploded plan view of each component member according to the tenth embodiment. FIG. 38 is a schematic diagram for explaining an operation principle of the lighting apparatus according to the tenth embodiment. It is a graph which shows the reflectance of the fluorescent screen in which the antireflection film was formed. It is a graph which shows the relationship between the wavelength of the incident light to a filter, and the transmittance | permeability which incident light permeate | transmits a filter.

Explanation of symbols

  101 lens, 102, 111, 112, 113, 119 rotating mirror, 102a, 111a, 112a reflecting surface, 103, 120, 121, 122 fluorescent plate, 103a irradiated surface, 103b back surface, 104 housing, 104a front surface, 104b back surface, 105, 105a, 105b, 105c Laser beam trajectory, 106 illumination light, 107 laser irradiation area, 108 antireflection film, 109, 116, 117, 118 reflector, 110, 123 filter, 114 rotation axis, 115 illumination light extraction window 119a Top surface.

Claims (12)

A semiconductor laser element;
A parallel light generating unit that makes laser light generated from the semiconductor laser element substantially parallel light;
A reflection unit having a movable mechanism and reflecting the laser light transmitted through the parallel light generation unit;
A fluorescent portion laser beam reflected comprises a phosphor that converts the laser light being excited by irradiation to fluorescence by the reflective portion,
An optical system that projects the fluorescence in one direction ,
The laser beam reflected by the reflection unit is scanned by moving the reflection unit by the movable mechanism,
The said fluorescent substance is an illuminating device arrange | positioned on the locus | trajectory of the laser beam which scans the said fluorescence part. The illumination device according to claim 1, wherein the optical system is a reflecting mirror having a concave surface. The concave surface includes a parabolic shape;
The illuminating device according to claim 2, wherein the fluorescent portion is disposed at a parabolic focal point. The fluorescent part includes a fluorescent plate in which the phosphor is linearly enclosed,
The reflection part includes a rotary mirror provided rotatably,
The illuminating device according to claim 1, wherein the rotating mirror is installed so as to scan a laser beam by rotation and irradiate the phosphor encapsulated in a linear shape with the laser beam. The fluorescent part includes a fluorescent plate in which the phosphor is enclosed,
The illuminating device according to claim 1, wherein fluorescence obtained by converting laser light by the phosphor is emitted from a surface to be irradiated on the side on which the fluorescent plate is irradiated with laser light. The lighting device according to claim 5 , wherein a reflecting plate is provided on a side opposite to the irradiated surface with respect to the fluorescent plate. Wherein provided on the illuminated surface side with respect to the fluorescent plate, to suppress from being released to the lighting device external laser light is reflected by the surface to be illuminated, further comprising a laser beam cutting unit, according to claim 5 Lighting equipment. The illumination device according to claim 7 , wherein the laser light cut portion includes an antireflection film that is formed on the irradiated surface and prevents reflection of light having a wavelength of laser light on the irradiated surface. The illumination device according to claim 7 , wherein the laser light cut unit includes a filter that is provided apart from the irradiated surface and blocks light having a wavelength of the laser light. The fluorescent part includes a fluorescent plate in which the phosphor is enclosed,
The fluorescence in which laser light is converted by the phosphor is emitted from both an irradiated surface on the side where the phosphor plate is irradiated with laser light and a back surface opposite to the irradiated surface. The lighting device described. A part of the laser light directly irradiated on the fluorescent part from the reflective part is reflected by the fluorescent part,
The illumination device according to claim 1, wherein the laser light reflected by the fluorescent part is irradiated again on the fluorescent part and converted into fluorescent light.   The illuminating device according to claim 1, wherein a wavelength of laser light oscillated by the semiconductor laser element is not less than 400 nm and not more than 450 nm.

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