JP6691677B2 - Lighting equipment - Google Patents

Description

  The present invention relates to an illumination device that uses coherent light.

  Conventionally, the illuminating device of patent document 1 is known as an illuminating device using coherent light. This illuminating device has an optical element including a hologram recording medium that directs the traveling direction of the coherent light toward the illuminated area, and an irradiating device that irradiates the optical element with the coherent light. The irradiation device has three laser light sources that generate red, green, and blue coherent light, and a scanning device that directs the traveling direction of the coherent light from these laser light sources to the optical element. The optical element has a transmissive or reflective hologram recording medium, and the hologram recording medium is provided with three recording areas corresponding to the three laser light sources. The coherent light emitted from each laser light source and having its optical path bent by the scanning device enters the corresponding recording area of the optical element. The coherent light entering each recording area of the optical element is diffused in the recording area and illuminates the illuminated area.

International Publication No. 2012/033174

  The inventors of the present invention are studying configuring an illumination device using coherent light as shown in FIG. The illuminating device 110 shown in FIG. 4 has a reflective light diffusing element 120 including a reflective hologram recording medium 121, and an irradiating device 130 for irradiating the reflective light diffusing element 120 with coherent light. The irradiation device 130 includes a plurality of light sources 131 that generate and emit coherent light, an optical scanning mechanism 135 that scans the coherent light emitted from these light sources 131, and an optical path of the light from the light source 131 that is folded back. And a folding optical system 140 for directing the light to the reflection type light diffusing element 120. In the illustrated illumination device, the coherent light emitted from each light source 131 is scanned by the optical scanning mechanism 135, its optical path is folded back by the folding optical system 140, and enters the reflection-type light diffusing element 120. In the example shown in FIG. 4, in the reflective hologram recording medium 121 of the reflective light diffusing element 120, three recording areas 121a, 121b, 121c corresponding to the three light sources 131 are arranged along the first direction d1. Are provided. The coherent light entering the reflective light diffusing element 120 from the irradiation device 130 enters the corresponding recording areas 121 a, 121 b, 121 c of the reflective hologram recording medium 121. The coherent light incident on each of the recording areas 121a, 121b, 121c of the reflective hologram recording medium 121 is diffused in the recording area and illuminates the illuminated area LZ as illumination light Lb.

  The inventors of the present invention have studied the illumination device 110. As a result, in the reflection hologram recording medium 121 of the reflection light diffusing element 120, the light is diffused in the recording area 121a on the folding optical system 140 side along the first direction d1. It has been found that a part of the illuminated light Lb thus generated is blocked by the folding optical system 140 and does not reach the illuminated region LZ, and a shadow S may occur in the illuminated region LZ.

  In order to solve this problem, it is conceivable to widen the distance between the reflective light diffusing element 120 and the folding optical system 140 along the first direction d1. However, according to this method, the incident angle of the coherent light on the reflective light diffusing element 120 becomes large, that is, the incident direction of the coherent light on the reflective light diffusing element 120 and the plate surface of the reflective light diffusing element 120. The angle formed by the normal direction (the second direction d2 in FIG. 4) becomes large. Along with this, the distance between the folding optical system 140 and the light scanning mechanism 135 along the first direction d1 and the distance between the light scanning mechanism 135 and the light source 131 along the first direction d1 must be increased. Therefore, the entire illumination device 110 becomes large.

  In addition, the gap between the reflection-type light diffusing element 120 and the folding optical system 140 along the first direction d1 is widened, and the angle of the folding optical system 140 is changed, for example, the reflecting surface of the folding optical system 140 is in the first direction d1. It is conceivable to incline so as to face the other side. According to this method, it is possible to minimize the change of the positions of the light scanning mechanism 135 and the light source 131 along the first direction d1, and it is possible to suppress the size increase of the entire illumination device 110. However, according to this method, the incident angle of the coherent light (incident light) to the reflective light diffusing element 120 becomes large, so that the 0th order light (this incident light is reflected as it is by the reflective light diffusing element 120). The angle formed between the emission direction of the specular reflection light (assumed) and the emission direction of the illumination light that illuminates the illuminated region LZ is increased, and the diffraction efficiency of the reflective light diffusing element 120 is reduced.

  The present invention has been made in consideration of such a point, and an object thereof is to provide a lighting device that is downsized while preventing a shadow from being generated in the illumination light.

The lighting device of the present invention is
A lighting device comprising a reflection type light diffusing element and an irradiation device for irradiating the reflection type light diffusing element with coherent light,
The irradiation device,
A first light source and a second light source that emit coherent light;
An optical scanning mechanism for scanning the coherent light emitted from the first light source and the second light source;
A first turn-back optical system that turns back an optical path of light from the first light source and directs the light to the reflective light diffusing element;
A second folding optical system for folding the optical path of the light from the second light source and directing the light to the reflective light diffusing element.

  In the illuminating device of the present invention, the reflective light diffusing element has a plurality of regions arranged in a first direction, and the first folding optical system and the second folding optical system are arranged in the first direction. May be done.

  In the illumination device of the present invention, the first folding optical system is located on one side in the first direction with respect to the reflective light diffusing element, and the second folding optical system is arranged on the reflective light diffusing element. On the other hand, it may be located on the other side of the first direction.

  According to the present invention, it is possible to provide a miniaturized lighting device while preventing a shadow from being generated in the illumination light.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a diagram schematically showing a lighting device. FIG. 2 is a top view of the lighting device of FIG. FIG. 3 is a diagram for explaining the structure of the reflective light diffusing element of the lighting device of FIG. FIG. 4 is a diagram schematically showing a lighting device of a comparative form.

  An embodiment of the present invention will be described below with reference to the drawings. In addition, in the drawings attached to the present specification, for convenience of illustration and understanding, the scale, the vertical and horizontal dimension ratios, etc. are appropriately changed and exaggerated from the actual ones.

  1 to 3 are diagrams for explaining an embodiment of the present invention. As shown in FIG. 1, the illuminating device 10 includes a reflective light diffusing element 20 that directs the traveling direction of coherent light toward the illuminated region LZ, and an irradiating device 30 that irradiates the reflective light diffusing element 20 with coherent light. Have The reflective light diffusing element 20 includes a reflective hologram recording medium 21 that functions as a light diffusing element or a light diffusing element. In the illustrated example, the reflective light diffusing element 20 is formed of a reflective hologram recording medium 21.

  In the illustrated example, the reflection hologram recording medium 21 forming the reflection light diffusion element 20 receives the coherent light emitted from the irradiation device 30 as the incident light La and diffracts the coherent light with high efficiency. be able to. In particular, the reflection hologram recording medium 21 can reproduce the image 5 by diffracting the coherent light incident on each position, in other words, each minute region which should also be called each point thereof. ..

  As the reflective hologram recording medium 21 that enables such a diffracting action of coherent light, for example, a reflective volume hologram using a photopolymer can be used. As an example, the reference light and the object light are exposed to the hologram recording material to generate interference fringes formed by the interference of the reference light and the object light. Examples of the rate modulation pattern) include those recorded on a hologram recording material. The method for producing the reflection hologram recording medium 21 is not particularly limited, but it can be produced by the method disclosed in JP 2012-123382 A, for example.

  In the present embodiment, the reflective hologram recording medium 21 of the reflective light diffusing element 20 has three recording areas 21a corresponding to respective light sources 31a, 31b, and 32a, which will be described later, along the first direction d1. , 21b, 21c are provided (see FIGS. 1 and 3). Particularly, in the illustrated example, the first direction d1 is parallel to the plate surface of the reflective hologram recording medium 21. The functions of these recording areas 21a, 21b, 21c will be described later.

  The irradiation device 30 irradiates the reflective light diffusing element 20 with the coherent light La so that the coherent light scans the reflective hologram recording medium 21 of the reflective light diffusing element 20. Therefore, the region on the reflective hologram recording medium 21 irradiated with the coherent light La by the irradiation device 30 at a certain moment becomes a part of the entire surface of the reflective hologram recording medium 21.

  Then, the coherent light La emitted from the irradiation device 30 and scanning on the reflective hologram recording medium 21 satisfies the diffraction condition of the reflective hologram recording medium 21 at each position on the reflective hologram recording medium 21. It is designed to be incident at an incident angle. The coherent light La that has entered each position of the reflective hologram recording medium 21 from the irradiation device 30 is diffracted by the reflective hologram recording medium 21 and illuminates an area at least partially overlapping with each other. Particularly, in the embodiment described here, the coherent light La that has entered each position of the reflective hologram recording medium 21 from the irradiation device 30 is diffracted by the reflective hologram recording medium 21 and illuminates the same illuminated region LZ. It is like this. More specifically, as shown in FIG. 1, the coherent light La incident on each position of the reflection type hologram recording medium 21 from the irradiation device 30 is adapted to reproduce the image 5 while being superposed on the illuminated region LZ. ing. That is, the coherent light La that has entered each position of the reflective hologram recording medium 21 from the irradiation device 30 is diffused (spread) by the reflective light diffusing element 20 and enters the same illuminated region LZ. Like

  The irradiation device 30 that irradiates the reflection-type light diffusing element 20 including the reflection-type hologram recording medium 21 with the coherent light La can be configured as follows. In the example shown in FIG. 1, the irradiation device 30 includes a first light source 31 and a second light source 32 which emit coherent light (for example, laser light) L11 and L12, and coherent light L11, which is emitted from the light sources 31 and 32. An optical scanning mechanism 35 that scans L12, a first return optical system 40 that returns the optical path of the light L11 from the first light source 31 and directs the light to the reflective light diffusing element 20, and a light from the second light source 32. And a second folding optical system 50 that folds the optical path of L12 and directs the light to the reflective light diffusing element 20.

  In the example shown in FIG. 1, the first light source 31 has two light sources 31a and 31b. The second light source 32 has one light source 32a. Each of the light sources 31a, 31b, 32a has a function of generating and emitting coherent light. In the illustrated example, the light sources 31a, 31b, 32a generate and emit coherent light having different wavelength bands. As an example, the light source 31a generates and emits red laser light, the light source 31b generates and emits green laser light, and the light source 32a generates and emits blue laser light. In addition to these three types of light sources, a light source having a separate wavelength band, that is, a light source emitting light of another color (for example, yellow) may be provided. Further, at least one of the light sources 31a, 31b, 32a may be replaced with a light source which emits light of another color. Further, in the illustrated example, each of the light sources 31a, 31b, 32a is a coherent light beam from one side of the first direction d1 to the other side and from one side of the second direction d2 intersecting the first direction to the other side. L11 and L12 are ejected. In the illustrated example, the first direction d1 and the second direction d2 are orthogonal to each other. In particular, the second direction d2 is parallel to the direction normal to the plate surface of the reflective hologram recording medium 21 of the reflective light diffusing element 20.

  The light scanning mechanism 35 scans the coherent light L11, L12 emitted from each light source 31a, 31b, 32a, and directs the optical path of each coherent light L11, L12 to the first folding optical system 40 or the second folding optical system 50. .. Particularly, in the example shown in FIG. 1, the optical scanning mechanism 35 directs the optical path of the coherent light L11 emitted from the first light source 31 (the light sources 31a and 31b) toward the first folding optical system 40 and directs the second light source 32 (the light source). The optical path of the coherent light L12 emitted from 32a) is directed to the second folding optical system 50.

  The optical scanning mechanism 35 includes a reflecting device 36 having a reflecting surface 36a that is rotatable about one axis RA. In particular, in the example shown in FIGS. 1 and 2, the reflecting device 36 is configured as a polygon mirror having a plurality of reflecting surfaces (mirrors) 36a rotatable about one axis RA. The reflecting device 36 changes the optical path of the coherent light L11, L12 from the light sources 31a, 31b, 32a by changing the orientation of each reflecting surface 36a. In the example shown in FIG. 1, the reflection surface 36a of the reflection device 36 is emitted from the light sources 31a, 31b, 32a, and enters the coherent light L11, which enters from one side of the first direction d1 and one side of the second direction d2. L12 is reflected toward the other side of the first direction d1 and the one side of the second direction d2. At this time, the reflection device 36 of the light scanning mechanism 35 changes the traveling direction of the light L11, L12 from the light sources 31, 32 with time.

  FIG. 2 is a top view showing the first light source 31, the light scanning mechanism 35, the first folding optical system 40, and the reflection type light diffusing element 20 of the illuminating device 10 of FIG. In the example shown in FIGS. 1 and 2, the rotation axis RA of the plurality of reflecting surfaces 36a extends parallel to the first direction d1. Therefore, the rotation axis RA of the reflection device 36 is parallel to the arrangement direction of the plurality of recording areas 21a, 21b, 21c of the reflection hologram recording medium 21 of the reflection light diffusing element 20.

  The coherent light L21 that has entered the reflecting surface 36a of the reflecting device 36 from the light sources 31a and 31b and is reflected by the reflecting surface 36a is accompanied by the rotation of the reflecting device 36 about the rotation axis RA, and the traveling direction thereof. Changes over time. Specifically, as shown in FIG. 2, the coherent light L21 is repeatedly scanned along the third direction d3 intersecting the first direction d1. In particular, the coherent light L21 reflected by the reflection surface 36a of the reflection device 36 is repeatedly scanned from one side of the third direction d3 toward the other side. In the illustrated example, the first direction d1 and the third direction d3 are orthogonal to each other. In particular, the third direction d3 is parallel to the plate surface of the reflective hologram recording medium 21 of the reflective light diffusing element 20. Further, the second direction d2 and the third direction d3 intersect, especially orthogonal.

  The first folding optical system 40 folds the optical path of the coherent light L21 emitted from the first light source 31 (the light sources 31a and 31b) and reflected by the reflection surface 36a of the reflection device 36 of the optical scanning mechanism 35 to emit the coherent light. It is directed to the reflective light diffusing element 20. In addition, the second folding optical system 50 folds the optical path of the coherent light L22 emitted from the second light source 32 (light source 32a) and reflected by the reflection surface 36a of the reflection device 36 of the optical scanning mechanism 35 to emit the coherent light. It is directed to the reflective light diffusing element 20.

  In the example shown in FIG. 1, the first folding optical system 40 and the second folding optical system 50 are arranged in the first direction d1. In the illustrated example, the first folding optical system 40 is located on one side of the reflective light diffusing element 20 in the first direction d1, and the second folding optical system 50 is located on the reflective light diffusing element 20. And is located on the other side of the first direction d1. In particular, the first folding optical system 40 is located on the optical scanning mechanism 35 side in the first direction d1 with respect to the reflective light diffusing element 20, and the second folding optical system 50 is located with respect to the reflective light diffusing element 20. It is located on the opposite side of the optical scanning mechanism 35 in the first direction d1.

  The first folding optical system 40 folds the coherent light L21 emitted from the first light source 31 (light sources 31a and 31b) and scanned by the light scanning mechanism 35, and guides it to the reflective light diffusing element 20. It includes a first mirror 41 having one reflecting surface 41a. Further, the second folding optical system 50 folds the coherent light L22 emitted from the second light source 32 (light source 32a) and scanned by the light scanning mechanism 35, and guides it to the reflective light diffusing element 20. It includes a second mirror 51 having two reflecting surfaces 51a.

  In the example shown in FIG. 1, the first reflecting surface 41a of the first mirror 41 of the first folding optical system 40 is arranged so as to face substantially the other side in the second direction d2. In addition, the second reflecting surface 51a of the second mirror 51 of the second folding optical system 50 is oriented in the first direction d1 and the second direction so as to face substantially one side of the first direction d1 and the other side of the second direction d2. It is arranged so as to face a direction inclined with respect to d2. As a result, the first reflecting surface 41 a of the first mirror 41 is emitted from the first light source 31 (light sources 31 a and 31 b), reflected by the reflecting surface 36 a of the reflecting device 36 of the optical scanning mechanism 35, and then the first reflecting surface 41 a. The coherent light L21 that has entered 41a from one side of the first direction d1 and the other side of the second direction d2 is reflected toward the other side of the first direction d1 and the other side of the second direction d2. The second reflection surface 51a of the second mirror 51 is emitted from the second light source 32 (light source 32a), reflected by the reflection surface 36a of the reflection device 36 of the optical scanning mechanism 35, and is reflected by the second reflection surface 51a. The coherent light L22 incident from one side of the first direction d1 and the other side of the second direction d2 is reflected toward one side of the first direction d1 and the other side of the second direction d2.

  In the present embodiment, the reflection device 36 of the optical scanning mechanism 35 changes the traveling direction of the coherent light from the light sources 31 and 32 with time. Therefore, the coherent light beams L21 and L22 reflected by the reflection device 36 of the optical scanning mechanism 35 scan the reflection surfaces 41a and 51a of the mirrors 41 and 51 of the folding optical systems 40 and 50. Therefore, the folding optical systems 40 and 50 are configured to exert a collimating function in a plane intersecting the rotation axis RA of the reflection device 36 of the optical scanning mechanism 35. That is, the reflection surfaces 41a and 51a of the mirrors 41 and 51 of the folding optical systems 40 and 50 are in the direction intersecting the rotation axis RA of the reflection device 36 in the optical scanning mechanism 35 (the third direction d3 in the example shown in FIG. 2). The coherent light beams L21 and L22 incident on the optical path of the light beam diverging in the direction intersecting the rotation axis RA of the reflection device 36 are collimated and the coherent light beams L21 and L22 are collimated light La1. , La2. Therefore, as shown in FIG. 2, the reflecting surfaces 41a and 51a are formed to be concave. Specifically, the reflection surfaces 41a and 51a are, in a cross section that intersects with the rotation axis RA of the reflection device 36 of the optical scanning mechanism 35, a direction that intersects with the rotation axis RA of the reflection device 36 (the example illustrated in FIG. 2). Has a concave surface configured such that its normal direction changes from one side to the other side along the third direction d3). In particular, in the illustrated example, the reflecting surfaces 41a and 51a are configured as parabolic concave surfaces in a cross section that intersects the rotation axis RA of the reflecting device 36. As a result, the coherent light beams La1 and La2 traveling from the folding optical systems 40 and 50 to the reflective light diffusing element 20 follow the optical paths of the light rays forming the parallel light flux. The folding optical systems 40 and 50 are arranged not only in the plane intersecting the rotation axis RA of the reflection device 36 of the optical scanning mechanism 35, but also in the plane parallel to the rotation axis RA of the reflection device 36 of the optical scanning mechanism 35. It may be configured to exert a collimating function.

  Next, the details of the reflective light diffusing element 20 will be described. Here, as an example, the light source 31a of the first light source 31 generates and emits red laser light, the light source 31b of the first light source 31 generates and emits green laser light, and the light source 32a of the second light source 32 An example of generating and emitting blue laser light will be described.

  As shown in FIG. 3, the reflective hologram recording medium 21 of the reflective light diffusing element 20 is provided with three recording areas 21a, 21b and 21c corresponding to the light sources 31a, 31b and 32a, respectively. The red coherent light from the light source 31a reflected by the light scanning mechanism 35 and the first folding optical system 40 is incident on the recording area 21a, whereby the image 5 composed of red reproduction light is illuminated over the entire illuminated area LZ. Is generated. The light scanning mechanism 35 changes the reflection angle of the red coherent light from the light source 31a over time, and the irradiation position of the red coherent light in the recording area 21a also changes accordingly, but it is out of the recording area 21a. The reflection angle of the optical scanning mechanism 35 is controlled so that the red coherent light does not enter the position.

  Similarly, in the recording area 21b, the green coherent light from the light source 31b reflected by the optical scanning mechanism 35 and the first folding optical system 40 is incident, and the image 5 composed of the green reproduction light is incident on the entire illuminated area LZ. Is generated. Further, the blue coherent light from the light source 32a reflected by the light scanning mechanism 35 and the second folding optical system 50 is incident on the recording area 21c, and the image 5 composed of the blue reproduction light is spread over the entire illuminated area LZ. Is generated.

  As a result, the illuminated area LZ is illuminated with three colors of red, green and blue. When the light sources 31a, 31b, and 32a simultaneously emit coherent light, these three colors are mixed in the illuminated area LZ and are illuminated in white.

  Here, the recording areas 21a, 21b, and 21c may be arranged in close contact with each other, or there may be a gap therebetween. When there is a gap between the recording areas 21a, 21b, and 21c, the coherent light reflected by the optical scanning mechanism 35 and the folding optical systems 40 and 50 will not enter the gap, but there is no practical problem. .. Further, the recording areas 21a, 21b, 21c need not have the same area. However, if interference fringes are formed overlappingly in these recording areas 21a, 21b, 21c, the amount of refractive index modulation per interference fringe corresponding to each color becomes small, and as a result, compared with the case where there is a monochromatic interference fringe. As a result, the brightness of the illuminated area LZ becomes different. Therefore, it is desirable that the recording areas 21a, 21b, 21c do not overlap.

  To provide the recording areas 21a, 21b, and 21c on the reflective hologram recording medium 21, for example, in the method disclosed in Japanese Unexamined Patent Publication No. 2012-123382, the reference light and the object light are irradiated to each recording area, Interference fringes may be formed in the corresponding recording area.

  Depending on the characteristics of the light sources 31a, 31b, and 32a, it may be possible to reproduce a color closer to white by separately providing a light source that emits a color other than red, green, and blue (for example, a light source that emits yellow). .. Therefore, the type of light source provided in the irradiation device 30 is not particularly limited. For example, when four color light sources are provided, the reflective hologram recording medium 21 may be divided into four regions in association with the respective light sources.

  The optical scanning mechanism 35 changes the traveling direction of the coherent light with time and directs it in various directions so that the traveling direction of the coherent light is not constant. As a result, the coherent light whose traveling direction is changed by the light scanning mechanism 35 is reflected by the folding optical systems 40 and 50 and scans the incident surface of the reflective hologram recording medium 21 of the reflective light diffusing element 20. become. In the example of FIG. 1, since three types of coherent light from the light sources 31a, 31b, and 32a are incident on the optical scanning mechanism 35, the optical scanning mechanism 35 changes the reflection angle of these coherent light with time. The respective incident surfaces of the recording areas 21a, 21b and 21c of the reflective hologram recording medium 21 are scanned.

  Next, the operation of the lighting device 10 will be described.

  The irradiation device 30 of the illumination device 10 irradiates the reflective light diffusing element 20 with the coherent light La1 and La2 so that the coherent light La1 and La2 scan the reflective hologram recording medium 21 of the reflective light diffusing element 20. To do. Specifically, first, the light sources 31a and 31b of the first light source 31 and the light source 32a of the second light source 32 generate and emit coherent light L11 and L12, respectively. As an example, the light source 31a generates and emits red laser light L11, the light source 31b generates and emits green laser light L11, and the light source 32a generates and emits blue laser light L12. In the example shown in FIG. 1, the respective light sources 31a, 31b, 32a are coherent from one side of the first direction d1 to the other side and from one side of the second direction d2 intersecting the first direction to the other side. Lights L11 and L12 are emitted.

  The coherent light beams L11, L12 emitted from the light sources 31a, 31b, 32a are scanned by the reflection device 36 of the optical scanning mechanism 35. In the example shown in FIG. 1, the reflection device 36 of the optical scanning mechanism 35 is configured as a polygon mirror, and each of the coherent light beams L11 and L12 is reflected by any of the plurality of reflection surfaces 36a of the polygon mirror, and the folding optical system is used. Heading to systems 40 and 50. In the illustrated example, the optical scanning mechanism 35 directs the optical path of the coherent light L11 emitted from the first light source 31 (light sources 31a and 31b) toward the first folding optical system 40 and emits it from the second light source 32 (light source 32a). The optical path of the coherent light L12 is directed to the second folding optical system 50.

  At this time, the coherent light beams L21 and L22 that are incident from any one of the light sources 31a, 31b, and 32a to any one of the reflecting surfaces 36a of the reflecting device 36 and reflected by the reflecting surface 36a rotate about the rotation axis RA of the reflecting device 36. As a result, the traveling direction changes with time. In particular, the coherent light beams L21, L22 reflected by the reflection surface 36a of the reflection device 36 are from one side to the other side in the direction intersecting the rotation axis RA of the reflection device 36 (the third direction d3 in the example shown in FIG. 2). Is repeatedly scanned toward.

  The coherent light L21 emitted from the first light source 31 (light sources 31a and 31b) and reflected by the reflection surface 36a of the reflection device 36 of the optical scanning mechanism 35 has its optical path folded back by the first folding optical system 40 to form a reflection type light. Heading to diffusion element 20. Further, the coherent light L22 emitted from the second light source 32 (light source 32a) and reflected by the reflecting surface 36a of the reflecting device 36 of the optical scanning mechanism 35 has its optical path folded back by the second folding optical system 50 to form a reflection type light. Heading to diffusion element 20.

  With the rotation of the reflection device 36 of the light scanning mechanism 35, the traveling direction of the coherent light from the light sources 31 and 32 changes with time. Therefore, the coherent light beams L21 and L22 reflected by the reflection device 36 of the optical scanning mechanism 35 scan the reflection surfaces 41a and 51a of the mirrors 41 and 51 of the folding optical systems 40 and 50.

  Here, the reflection surfaces 41a and 51a of the mirrors 41 and 51 of the folding optical systems 40 and 50 are formed to be concave. As a result, the folding optical systems 40 and 50 exhibit a collimating function in the plane intersecting the rotation axis RA of the reflection device 36 of the optical scanning mechanism 35. Therefore, the light beam that is scanned by the optical scanning mechanism 35 in the direction intersecting the rotation axis RA of the reflection device 36 (the third direction d3 in the example shown in FIG. 2) and diverges in the direction intersecting the rotation axis RA of the reflection device 36. The coherent light beams L21 and L22 incident on the folding optical systems 40 and 50 by tracing the optical paths of are reflected by the folding optical systems 40 and 50, are collimated, and trace the optical paths of rays forming a parallel light flux. Heading to the reflective light diffusing element 20.

  As described above, the irradiation device 30 scans the reflective hologram recording medium 21 of the reflective light diffusing element 20 with the coherent light emitted from the light sources 31 and 32, so that the reflective light diffusing element 20 is exposed. The coherent light beams La1 and La2 are emitted.

  The irradiator 30 emits coherent light La1 and La2 having specific wavelengths at specific positions in the recording areas 21a, 21b, and 21c on the reflective hologram recording medium 21 at incident angles that satisfy the Bragg condition at the positions. Make it incident. As a result, the coherent light beams La1 and La2 incident on the specific positions in the respective recording areas are overlapped with each other to form the image 5 on the entire illuminated area LZ due to the diffraction caused by the interference fringes recorded on the reflective hologram recording medium 21. Reproduce. That is, the coherent light beams La1 and La2 that have entered the recording hologram recording medium 21 at specific positions from the irradiation device 30 are diffused (spread) by the reflective light diffusing element 20 to be illuminated. The light is incident on the entire region LZ. In this way, the illumination device 10 illuminates the illuminated area LZ with the coherent light Lb. In the example described above, the light sources 31a, 31b, 32a emit light in different colors of red, green, and blue, respectively, and the image 5 is reproduced in each color in the illuminated region LZ. Therefore, when the light sources 31a, 31b, and 32a emit light at the same time, the illuminated region LZ is illuminated with white in which three colors are mixed.

  The illumination device 10 of the present embodiment described above includes the reflective light diffusing element 20 and the irradiation device 30 that irradiates the reflective light diffusing element 20 with coherent light. The irradiation device 30 emits coherent light. The first light source 31 and the second light source 32, the optical scanning mechanism 35 that scans the coherent light emitted from the first light source 31 and the second light source 32, and the optical path of the light from the first light source 31 are folded back to A first folding optical system 40 for directing the light toward the reflective light diffusing element 20, and a second folding optical system 50 for folding the optical path of the light from the second light source 32 and directing the light toward the reflective light diffusing element 20. Have.

  In particular, the reflective light diffusing element 20 has a plurality of regions arranged in the first direction d1, and the first folding optical system 40 and the second folding optical system 50 are arranged in the first direction d1.

  In particular, the first folding optical system 40 is located on one side of the reflective light diffusing element 20 in the first direction d1, and the second folding optical system 50 is located in the first direction d with respect to the reflective light diffusing element 20. It is located on the other side of d1.

  In the illuminating device 10 of the present embodiment, the coherent light L11 from the first light source 31 is scanned by the optical scanning mechanism 35, then its optical path is folded back by the first folding optical system 40, and the coherent light L11 from the second light source 32 is emitted. The coherent light L12 is scanned by the optical scanning mechanism 35, and then the optical path of the coherent light L12 is reflected by the second folding optical system 50. That is, the coherent lights L21 and L22 emitted from the plurality of light sources 31 and 32 and scanned by the light scanning mechanism 35 are divided into the light L21 toward the first folding optical system 40 and the light L22 toward the second folding optical system 50. The optical paths are turned back by the turning optical systems 40 and 50, respectively. Therefore, in comparison with the illumination device 110 shown in FIG. 4, that is, the illumination device 110 in which coherent light from a plurality of light sources 131 is scanned by the optical scanning mechanism 135 and then its optical path is folded back by one folding optical system 140. Thus, the dimension of the first folding optical system 40 along the first direction d1 can be reduced.

  As a result, a part of the illumination light diffused in the recording region 21a of the reflective hologram recording medium 21 of the reflective light diffusing element 20 on the first folding optical system 40 side along the first direction d1 is first folded. It is possible to effectively prevent the shadow S from being generated in the illuminated area LZ without being reached by the optical system 40 to reach the illuminated area LZ.

  Further, since it is not necessary to increase the angle of incidence of the coherent light on the reflective light diffusing element 120, the distance between the first folding optical system 40 and the light scanning mechanism 35 along the first direction d1, and the light scanning mechanism. The distance between the light source 35 and the light sources 31 and 32 along the first direction d1 can be narrowed, and the illumination device 10 can be downsized.

  Further, since it is not necessary to increase the angle of incidence of the coherent light on the reflective light diffusing element 120, it is possible to reduce the angle between the direction of incidence of the incident light and the direction of emission of the illumination light that illuminates the illuminated area LZ. Therefore, the diffraction efficiency of the reflective light diffusing element 20 can be improved.

  Various modifications can be made to the above-described embodiment.

  In the above-described embodiment, the example in which the first light source 31 includes the two light sources 31a and 31b and the second light source 32 includes the one light source 32a is shown. However, the first light source 31 and the second light source 32 are The number of light sources included in each is arbitrary. For example, the first light source 31 may include one light source and the second light source 32 may include two light sources.

  In addition to the three types of light sources of red, green, and blue as shown in the above-described embodiment, when a light source having another wavelength band, that is, emitting light of another color (for example, yellow) is provided, For example, each of the first light source 31 and the second light source 32 may include two light sources.

  In the above-described embodiment, the reflection device 36 including the polygon mirror is used as the optical scanning mechanism 35, but the optical scanning mechanism 35 can scan the coherent light beams L11 and L12 emitted from the light sources 31 and 32. However, it is not limited to the reflection device 36 including a polygon mirror. As the optical scanning mechanism 35, for example, a reflection device (for example, a MEMS mirror) that can rotate around at least one rotation axis can be used.

  In the above-described embodiment, the coherent light L11 emitted from the light source 31 and the coherent light L12 emitted from the light source 32 are both reflected by the same reflection surface 36a of the reflection device 36 of the optical scanning mechanism 35. However, the reflection device 36 of the optical scanning mechanism 35 is not limited to this, so that the coherent light L11 emitted from the light source 31 and the coherent light L12 emitted from the light source 32 are reflected by different reflection surfaces 36a. May be configured.

  Although some modifications of the above-described embodiment have been described above, it is of course possible to appropriately combine and apply a plurality of modifications.

5 image 10 illumination device 20 reflection type light diffusing element 21 reflection type hologram recording medium 21a recording area 21b recording area 21c recording area 30 irradiation device 31 first light source 31a light source 31b light source 32 second light source 32a light source 35 optical scanning mechanism 36 reflection device 36a Reflecting surface 40 First folding optical system 41 First mirror 41a Reflecting surface 50 Second folding optical system 51 Second mirror 51a Reflecting surface

Claims (3)

A lighting device comprising a reflection type light diffusing element and an irradiation device for irradiating the reflection type light diffusing element with coherent light,
The irradiation device,
A first light source and a second light source that emit coherent light;
An optical scanning mechanism for scanning the coherent light emitted from the first light source and the second light source;
A first turn-back optical system that turns back an optical path of light from the first light source and directs the light to the reflective light diffusing element;
A second folding optical system that folds the optical path of the light from the second light source and directs the light to the reflective light diffusing element,
The first folding optical system and the second folding optical system are configured as separate bodies,
Of the light from the first light source and the light from the second light source, only the light from the first light source is incident on the first folding optical system,
Of the light from the first light source and the light from the second light source, only the light from the second light source is incident on the second folding optical system. The reflective light diffusing element has a plurality of regions arranged in a first direction,
The illumination device according to claim 1, wherein the first folding optical system and the second folding optical system are arranged in the first direction.   The first folding optical system is located on one side in the first direction with respect to the reflective light diffusing element, and the second folding optical system is located in the first direction with respect to the reflective light diffusing element. The lighting device according to claim 2, which is located on the other side.

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