JP2015141393A - Illumination device and projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination device that can illuminate at sufficiently even luminance while making speckle unnoticeable.SOLUTION: An illumination device 40 comprises: a first diffusion element 50; an irradiation device 70 that irradiates the first diffusion element with coherent light so as to scan on the first diffusion element; a deflection element 55 that changes an optical path of the coherent light diffused by the first diffusion element; a uniformization optical element 65 through which incident light passes while totally reflected; and a second diffusion element 60 that is arranged in the optical path from the deflection element to the uniformization optical element. The coherent light, which is incident upon a certain area on the first diffusion element and diffused, and the coherent light, which is incident upon other area different from the certain area on the first diffusion element and diffused, are respectively converged to the second diffusion element by the deflection element, pass through the uniformization optical element after diffused by the second diffusion element, and are used in illumination.

Description

  The present invention relates to an illumination device and a projection device having the illumination device.

  For example, as disclosed in Patent Document 1, an illumination device using an optical element including a lens array or a hologram is known. In particular, the illumination device disclosed in Patent Document 1 includes an irradiation device including a light source that emits coherent light and a scanning device that periodically changes the optical path of light from the light source. In this illumination device, the optical path of light incident on each area on the optical element is adjusted by the optical element and directed to a certain illuminated area. As a result, the illuminated area is illuminated from various directions corresponding to each area on the optical element.

  In an illumination device that emits coherent light such as laser light, there is a problem of speckle generation. A speckle is a speckled pattern that appears when a scattering surface is irradiated with coherent light such as laser light. For example, speckle is observed as spot-like luminance unevenness (brightness unevenness) when it occurs on the screen, and causes a physiological adverse effect on the observer. According to the illumination device disclosed in Patent Document 1, since the incident angle of the illumination light on the scattering surface changes with time, speckles on the scattering surface generated by the diffusion of the coherent light are superimposed and temporally. Averaged to be inconspicuous.

WO2012 / 033179A1

By the way, the present inventors are considering adding a homogenizing optical element 165 to the illumination device 140 as shown in FIG. 7 from the viewpoint of uniformizing the illuminance distribution in the illuminated area. In the illumination device 140 shown in FIG. 7, an optical element 145 having a diffusing element 150 and a condenser lens 155 is used. The condenser lens directs the optical path of the divergent light beam from the diffusing element toward the incident surface of the uniformizing optical element. Speckle invisibility in the illumination device can be achieved by increasing the magnitude θ _xa of the angle variation of the optical axis of the incident light beam incident on the uniformizing optical element from the condenser lens.

On the other hand, the intensity θ _ya of the diffusibility in the diffusing element does not directly contribute to speckle reduction. From the viewpoint of more reliably guiding the light source light to the homogenizing optical element and using it with higher utilization efficiency, it is effective not to widen the diffusion angle θ _ya at the diffusion element too much. Further, from the viewpoint other than the utilization efficiency of the light source light, as shown in FIGS. 8 and 9, there is a restriction on increasing the diffusion angle θ _ya in the diffusion element. As shown in FIG. 8, when the diffusion angle θ _yb in the diffusing element 150 is set large, it is necessary to use a large condenser lens 156, and the illuminating device is also enlarged. Further, as shown in FIG. 9, in order to increase the diffusion angle θ _yb in the diffusing element 150 without increasing the size of the condenser lens 155, it is necessary to reduce the size of the diffusing element 151. If the diffusing element 151 is reduced in size, the magnitude of the angle variation of the optical axis θ _xb becomes smaller, and the speckle cannot be made inconspicuous enough.

However, if the diffusion angle θ _ya at the diffusing element is small, the total reflection is not sufficiently repeated in the uniformizing optical element 165, depending on the length of the uniformizing optical element 165, as shown in FIG. . As a result, at each moment, light is emitted only from a part of the emission surface of the uniformizing optical element 165. That is, zone LZ _a that enables illumination at each instant is becomes a part of the illumination zone LZ facing the exit surface of uniformizing optics 165, it is possible to illuminate the illumination zone LZ at uniform illuminance Can not.

  The present invention has been made in consideration of the above points, and provides an illuminating device capable of illuminating with sufficiently uniform illuminance while making speckles inconspicuous, and a projection device using the illuminating device. The purpose is to do.

The lighting device according to the present invention comprises:
A first diffusing element;
An irradiation device for irradiating the first diffusion element with coherent light so as to scan on the first diffusion element;
A deflection element for changing an optical path of coherent light diffused by the first diffusion element;
A uniformizing optical element through which the coherent light whose optical path has been changed by the deflecting element is reflected, and
A second diffusing element disposed in an optical path from the deflecting element to the homogenizing optical element,
Coherent light that has been incident and diffused on a certain region on the first diffusion element, and coherent light that has been incident and diffused on another region different from the certain region on the first diffusion element are: Each is collected by the deflecting element on the second diffusing element, diffused by the second diffusing element, and then passed through the uniformizing optical element and used for illumination.

  In the illumination device according to the present invention, the second diffusing element may include a concave lens.

  In the illumination device according to the present invention, the second diffusing element may include a convex lens.

  In the illumination device according to the present invention, the second diffusing element may be disposed on an incident surface of the uniformizing optical element.

  In the illuminating device according to the present invention, the principal point of the second diffusing element may be located on the rear focal point of the deflecting element.

  In the illumination device according to the present invention, a distance from the deflection element to the second diffusion element may be equal to or greater than a focal length of the deflection element.

  In the illumination device according to the present invention, a distance from the second diffusion element to the incident surface of the uniformizing optical element may be shorter than a distance from the deflection element to the second diffusion element.

  In the illumination device according to the present invention, a distance from the incident surface of the first diffusing element to the deflecting element is longer than a distance from the second diffusing element to the incident surface of the homogenizing optical element. It may be shorter than the distance to the second diffusion element.

  In the illumination device according to the present invention, the first diffusion element may have a lens array including a plurality of concave lenses.

  In the illumination device according to the present invention, the first diffusion element may have a lens array including a plurality of convex lenses.

  In the illumination device according to the present invention, the first diffusion element may include a hologram recording medium.

The projection apparatus according to the present invention
Any of the lighting devices according to the invention described above;
A spatial light modulator illuminated by light from the illumination device.

  The projection apparatus according to the present invention may further include a projection optical system that directs light from the spatial light modulator onto the projection target.

The projection display device according to the present invention is
Any of the projection devices according to the invention described above;
A projection object to which light is projected from the projection device.

  According to the present invention, speckles can be made inconspicuous, and illumination can be performed with sufficiently uniform illuminance.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a diagram showing a schematic configuration of a projection device and a projection display device. FIG. 2 is a diagram illustrating an illumination device included in the projection device of FIG. FIG. 3 is a partially enlarged view of FIG. FIG. 4 is a diagram corresponding to FIG. 2 and showing a modification of the illumination device. FIG. 5 is a view corresponding to FIG. 2 and showing another modification of the illumination device. FIG. 6 is a diagram corresponding to FIG. 1 and is a diagram illustrating still another modification of the illumination device. FIG. 7 is a diagram illustrating a reference example of the lighting device. FIG. 8 is a diagram illustrating another reference example of the lighting device. FIG. 9 is a diagram showing still another reference example of the lighting device.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  In addition, as used in this specification, the shape and geometric conditions and the degree thereof are specified, for example, terms such as “parallel”, “orthogonal”, “identical”, length and angle values, etc. are strictly Without being bound by meaning, it should be interpreted including the extent to which similar functions can be expected.

  A projection video display device 10 shown in FIG. 1 includes a screen 15 and a projection device 20 that projects video light. The projection device 20 includes an illumination device 40 that illuminates the illuminated region LZ located on the virtual plane with coherent light, a spatial light modulator 30 that is disposed at a position overlapping the illuminated region LZ, and is illuminated by the illumination device 40, A projection optical system 25 that projects coherent light from the spatial light modulator 30 onto the screen 15. That is, in one embodiment described here, the illumination device 40 is incorporated in the projection device 20 as an illumination device for illuminating the spatial light modulator 30. And although the illuminating device 40 illuminates the to-be-illuminated area | region LZ with coherent light, the device which makes speckle inconspicuous is made | formed in this illuminating device 40.

  First, the illumination device 40 will be described. As shown in FIG. 1, the illumination device 40 includes an irradiation device 70 that emits coherent light, an optical element 45 that directs light from the irradiation device to a predetermined region, and coherent light emitted from the optical element 45. And a homogenizing optical element 65 for guiding the coherent light diffused by the second diffusion element 60.

  In the illumination device 40, the irradiation device 70 irradiates the optical element 45 with coherent light so as to scan the optical element 45. Therefore, at a certain moment, the region on the optical element 45 irradiated with the coherent light by the irradiation device 70 becomes a part of the surface of the optical element 45. The optical element 45 receives coherent light incident on a certain area on the scanning path and coherent light incident on another area at a position shifted from the certain area on the scanning path. The optical paths are adjusted so as to be incident on the second diffusing element 60, respectively. In particular, in the embodiment described below, light incident on each of a plurality of regions obtained by dividing the first diffusion element 50 forming the incident surface of the optical element 45 into a plane is incident on the second diffusion element 60. The optical path of the coherent light irradiated to the optical element 45 from the irradiation device 70 is adjusted. The light incident on the second diffusing element 60 is diffused by the second diffusing element 60 and then passes through the homogenizing optical element 65 to be used for illuminating the illuminated region LZ.

  The irradiation device 70 includes a light source device 71 that emits coherent light in a specific wavelength band, and a scanning device 75 that directs the traveling direction of light from the light source device 71 toward the optical element 45. The light source device 71 includes a light source 72 that generates coherent light, for example, a laser light source 72.

  On the other hand, the scanning device 75 is a device that changes the optical path of coherent light from the light source 72 over time. In the illustrated example, the scanning device 75 has an optical path changing member that can rotate around a single rotation axis Ra. The optical path changing member itself has a function of changing the optical path of incident light. This optical path changing member rotates around one axis Ra. That is, the illustrated irradiation apparatus 70 is configured as a one-dimensional scanning device. As the optical path changing member, a prism or the like can be exemplified, but in the illustrated example, it is configured as a reflecting member 76 having a reflecting surface 76a. The reflection member 76 is held so as to be rotatable about a rotation axis Ra parallel to the reflection surface 76a. Such a scanning device 75 may be constituted by a resonant mirror device as an example.

  Next, the optical element 45 will be described. As described above, the optical element 45 has an optical path control function that directs incident light to each region in a specific direction according to the position of the region. The optical element 45 described here collects the second diffusion element 60 by changing the traveling direction of the incident light to each region. That is, the coherent light from the irradiation device 70 irradiated to each region obtained by dividing the incident surface of the optical element 45 into a plane is directed to the second diffusion element 60 after passing through the optical element 45.

  As shown in FIGS. 1 and 2, the optical element 45 includes a first diffusing element 50 that forms an incident surface of the optical element 45, and a deflecting element 55 that adjusts an optical path of coherent light diffused by the first diffusing element 50. ,have. As shown in FIG. 2, the optical element 45 diffuses incident light and widens the optical path width of the light. The deflecting element 55 corrects the optical path of the light beam from the optical element 45 whose optical path width is widened and collects it in the second diffusing element 60.

  As an example, in the example shown in FIGS. 1 and 2, the first diffusing element 50 may be configured to include a lens array 51 formed corresponding to the incident direction of light from the irradiation device 70. Here, the “lens array” is a collection of small lenses, also called unit lenses, and functions as an element that deflects the traveling direction of light by refraction or reflection. In the illustrated example, the lens array 51 is formed by spreading unit concave lenses 52 made of concave lenses. The plurality of unit concave lenses 52 constituting the lens array 51 are arranged on a virtual plane orthogonal to the optical axis of each concave lens. The lens array 51 diffuses light incident on each region corresponding to each unit concave lens 52. On the other hand, in one specific example shown in FIG. 2, the deflecting element 55 includes a lens 56 that functions as a condenser lens or a field lens disposed to face the lens array 51.

  Similar to the unit lens of the first diffusing element 50, the second diffusing element 60 can diffuse incident light and widen the optical path width. In the illustrated example, the second diffusing element 60 is formed as a concave lens 61.

  The homogenizing optical element 65 is an element provided to ensure uniform illuminance in the illuminated area LZ. The coherent light incident on the incident surface 65a of the homogenizing optical element 65 is repeatedly reflected, for example, totally reflected in the homogenizing optical element 65, and is emitted from the emitting surface 65b. As a result, the illuminance distribution on the exit surface 65b of the homogenizing optical element 65 becomes uniform. In the illustrated example, an area facing the emission surface 65b of the homogenizing optical element 65 is an illuminated area LZ. That is, by providing the uniformizing optical element 65, the entire area within the illuminated area LZ is illuminated with a uniform light amount.

  The homogenizing optical element 65 can be configured using, for example, an integrator rod 66. The integrator rod 66 has a cylindrical shape, and propagates the coherent light incident on the incident surface in the direction of the exit surface while totally reflecting the light on the inner wall. As a result, coherent light having a uniform amount of light is emitted from the exit surface of the integrator rod 66 throughout the exit surface. Here, the degree of homogenization varies depending on each usage pattern, but as a rough guide, the variation in the illuminance distribution on the exit surface is within 10%. The homogenizing optical element 65 is not limited to the integrator rod, and for example, a kaleidoscope or a light pipe can be used.

  Next, the spatial light modulator 30 will be described. The spatial light modulator 30 is disposed so as to overlap the illuminated area LZ. The spatial light modulator 30 is illuminated by the illumination device 40 to form a modulated image. The light from the illumination device 40 illuminates only the entire illuminated area LZ. Therefore, it is preferable that the incident surface of the spatial light modulator 30 has the same shape and size as the illuminated region LZ irradiated with light by the illumination device 40. In this case, it is because the light from the illuminating device 40 can be utilized with high utilization efficiency for the formation of a modulated image.

  The spatial light modulator 30 is not particularly limited, and various known spatial light modulators can be used. For example, a spatial light modulator that forms a modulated image without using polarized light, such as a digital mirror device (DMD), a transmissive liquid crystal microdisplay that forms a modulated image using polarized light, or a reflective LCoS (Liquid) Crystal On Silicon (registered trademark) can be used as the spatial light modulator 30.

  As in the example shown in FIG. 1, when the spatial light modulator 30 is a transmissive liquid crystal microdisplay, the spatial light modulator 30 illuminated in a planar shape by the illumination device 40 is coherent light for each pixel. By selecting and transmitting, a modulated image is formed on the screen of the display forming the spatial light modulator 30. The modulated image thus obtained is finally projected onto the screen 15 by the projection optical system 25 at the same magnification or scaled. Thereby, the observer can observe the image projected on the screen 15. The screen 15 may be configured as a transmissive screen or may be configured as a reflective screen.

  Next, the operation of the illumination device 40, the projection device 20, and the projection display device 10 having the above-described configuration will be described.

  First, the irradiation device 70 irradiates the first diffusion element 50 with coherent light so as to scan the first diffusion element 50 of the optical element 45. Specifically, coherent light of a specific wavelength band traveling along a certain direction is generated by the light source 72 of the light source device 71, and the traveling direction of the coherent light is changed by the scanning device 75. The scanning device 75 performs a periodic operation. As a result, the incident position of the coherent light on the first diffusion element 50 also changes periodically.

The coherent light incident on each unit concave lens 52 of the first diffusing element 50 is diffused by the diffusing function of the first diffusing element 50 and is incident on the deflecting element 55 with the optical path width widened. The coherent light incident on the deflection element 55 is directed to the second diffusion element 60 by the optical path adjustment function of the deflection element 55. That is, the coherent light incident on each region of the first diffusion element 50 is collected by the second diffusion element 60. In the illustrated example, the optical path of the coherent light incident on each region on the first diffusing element 50 is changed so that the optical axes indicated by the alternate long and short dash lines in FIG. 1 are parallel to each other. . Then, due to the optical path changing function in the deflecting element 55, the optical axes of the coherent light incident on each region on the first diffusing element 50 intersect at the rear focal point P _{f of the} lens 56 constituting the deflecting element 55. .

  The second diffusing element 60 is disposed at a position facing the incident surface 65 a of the homogenizing optical element 65. Therefore, the coherent light incident on the second diffusing element 60 is incident on the uniformizing optical element 65 with a divergence angle widened. The homogenizing optical element 65 has a function of making the in-plane distribution of the light quantity uniform by repeatedly causing total reflection of incident light. The divergent light diffused by the second diffusing element 60 is likely to be effectively subjected to the homogenizing action of the homogenizing optical element 65. That is, the coherent light can always be emitted with a uniform light amount from each position in the emission surface 65b of the homogenizing optical element 65 without depending on the incident region of the coherent light on the first diffusion element 50. It becomes like this. As described above, the irradiation device 70 can uniformly illuminate the illuminated area LZ facing the emission surface 65b of the homogenizing optical element 65 with coherent light.

  As shown in FIG. 1, in the projection device 20, the spatial light modulator 30 is arranged at a position overlapping the illuminated area LZ of the illumination device 40. For this reason, the spatial light modulator 30 is illuminated in a planar shape by the illumination device 40, and forms an image by selecting and transmitting the coherent light for each pixel. This image is projected onto the screen 15 by the projection optical system 25. The coherent light projected on the screen 15 is diffused and recognized as an image by the observer.

  By the way, the coherent light projected on the screen interferes by diffusion and causes speckle. On the other hand, according to the illuminating device 40 described here, speckles can be made extremely inconspicuous as described below.

  In order to make speckles inconspicuous, it is effective to multiplex parameters such as polarization, phase, angle, and time and increase the mode. The mode here refers to speckle patterns that are uncorrelated with each other. For example, when coherent light is projected from different directions onto the same screen from a plurality of laser light sources, there are as many modes as the number of laser light sources. In addition, when coherent light from the same laser light source is projected onto the screen from different directions at different times, the mode will be the same as the number of times the incident direction of the coherent light has changed during a time that cannot be resolved by the human eye. Will exist. When there are a large number of these modes, the interference patterns of light are uncorrelated and averaged, and as a result, speckles observed by the observer's eyes are considered inconspicuous.

  In the illumination device 40 described above, the coherent light is applied to the first diffusion element 50 so as to scan the first diffusion element 50. The coherent light incident on the first diffusing element 50 is adjusted in the optical path by the deflecting element 55 and then enters the uniformizing optical element 65 via the second diffusing element 60. Therefore, the incident direction of the coherent light incident on the homogenizing optical element 65 continues to change. The homogenizing function of the homogenizing optical element 65 is caused by total reflection inside the homogenizing optical element 65. Therefore, the traveling direction of the light beam emitted from the homogenizing optical element 65 at a certain moment is determined depending on the traveling direction when the light beam enters the uniformizing optical element 65. Assuming that the homogenizing function by the homogenizing optical element 65 is sufficiently exerted, the maximum incident angle when the light beam is incident on the incident surface 65a of the homogenizing optical element 65 is equal to the uniform light beam. The size of the maximum emission angle at the time of emission from the emission surface 65b of the opticalizing element 65 is the same, and similarly, the size of the minimum incident angle at the time of incidence of the light flux on the incident surface 65a of the uniformizing optical element 65 is It becomes the size of the minimum emission angle at the time of emission from the emission surface 65b of the optical element 65 for uniformizing the luminous flux.

  That is, the angle range of the coherent light exiting from the exit surface 65b of the homogenizing optical element 65 depends on the angle range of the incident angle when the light enters the entrance surface 65a of the homogenizing optical element 65. And since the incident angle of the coherent light to the homogenizing optical element 65 changes with time, the angular range of the emitting direction of the coherent light emitted from the emitting surface 65b of the homogenizing optical element 65 also changes. On the other hand, the angular range in the emission direction of the coherent light emitted from the emission surface 65b of the homogenizing optical element 65 at any moment is made uniform to some extent at each position in the emission surface 65b.

  That is, the coherent light incident on each area of the first diffusion element 50 from the irradiation device 70 illuminates the entire illuminated area LZ with the coherent light, but illuminates the illuminated area LZ. The illumination directions of coherent light are different from each other. Since the region on the first diffusion element 50 where the coherent light enters changes with time, the incident direction of the coherent light to the illuminated region LZ also changes with time.

  Considering the illuminated area LZ as a reference, coherent light constantly enters each area in the illuminated area LZ, but the direction of incidence always changes as shown by an arrow A1 in FIG. It will be. As a result, the light forming each pixel of the image formed by the light transmitted through the spatial light modulator 30 is projected to a specific position on the screen 15 while changing its optical path over time as indicated by an arrow A2 in FIG. Will come to be.

  From the above, according to the illumination device 40 described above, the incident direction of the coherent light changes temporally at each position on the screen 15 displaying the image, and this change is This is a speed that cannot be resolved by the human eye. As a result, a non-correlated coherent light scattering pattern is multiplexed and observed in the human eye. Therefore, speckles generated corresponding to each scattering pattern are overlapped and averaged and observed by an observer. Thereby, speckles can be made very inconspicuous for an observer who observes the image displayed on the screen 15.

  Note that conventional speckles observed by humans include not only speckles on the screen caused by scattering of coherent light on the screen 15, but also scattering of coherent light before being projected on the screen. Speckle on the projection device side can also occur. The speckle pattern generated on the projection device side is projected onto the screen 15 via the spatial light modulator 30 so that it can be recognized by the observer. However, according to the present embodiment, the coherent light continuously scans on the first diffusion element 50 of the optical element 45, and the coherent light incident on each region of the optical element 45 is a spatial light modulator. The whole area of the illuminated area LZ 30 is illuminated. That is, the optical element 45 forms a new wavefront that is separate from the wavefront used to form the speckle pattern, and is complex and uniform through the illuminated region LZ and the spatial light modulator 30. The screen 15 is illuminated. With the formation of a new wavefront in such an optical element 45, the speckle pattern generated on the projection device side is invisible.

Incidentally, as described above, the speckle invisibility in the illumination device 40 and the projection device 20 is caused by the magnitude θ _x of the optical axis of the incident light beam incident on the uniformizing optical element from the deflection element 55 (see FIG. This can be achieved by increasing 2). On the other hand, the intensity of the diffusing ability in the first diffusing element 50, that is, the magnitude of the divergence angle θ _y (see FIG. 2) is compared with the magnitude of the angular variation with time of the optical axis θ _x. It does not have a big influence on speckle reduction. For this reason, from the viewpoint of more reliably making the light source light incident on the incident surface 65a of the homogenizing optical element 65 and using the light source light with higher utilization efficiency, it is effective not to widen the diffusion angle in the diffusing element too much. is there. Rather, when the diffusion angle θ _yb in the diffusing element 150 is set large as shown in FIG. 8 as compared with the examples of FIGS. Will also increase in size. Alternatively, in order to increase the diffusion angle θ _yb in the diffusion element without increasing the size of the condenser lens 155, it is necessary to reduce the size of the diffusion element 151 as shown in FIG. If the diffusing element 151 is made small, the magnitude θ _xb of the angle variation of the optical axis becomes small, which is disadvantageous in terms of speckle reduction.

As described above, from the viewpoint of the utilization efficiency of the coherent light irradiated from the irradiation device 70, it is preferable that the diffusion angle θ _ya in the first diffusion element 50 is not too large. _Increasing the diffusion angle θ _ya is accompanied by other adverse effects.

However, if the diffusion angle θ _ya at the first diffusion element 50 is not large enough, the incident direction of the light incident on the uniformizing optical element 165 at each instant is narrow as shown in FIG. It will be aligned inside. In this case, unless the uniformizing optical element 165 is sufficiently long, total reflection is not sufficiently repeated in the uniformizing optical element 165. If the uniformizing optical element 165 is lengthened, there is a disadvantage that the illumination device 40 is naturally enlarged. If the total reflection in the homogenizing optical element 165 is not sufficiently generated, light is emitted only from _a partial region LZa of the exit surface of the homogenizing optical element 165 at each moment. That is, zone LZ _a that enables illumination at each instant is becomes a part of the illumination zone LZ facing the exit surface of uniformizing optics 165, it is possible to illuminate the illumination zone LZ at uniform illuminance Can not.

On the other hand, in the present embodiment, the second diffusing element 60 is disposed in the optical path from the deflecting element 55 to the uniformizing optical element 65. The second diffusing element 60 is disposed so as to face the incident surface 65 a of the uniformizing optical element 65. Therefore, the second diffusing element 60 can widen the divergence angle θ _z (see FIG. 2) of the coherent light that enters the uniformizing optical element 65 at each instant immediately before entering the uniformizing optical element 65. . That is, the incidence of coherent light incident on the uniformizing optical element 65 at an arbitrary moment without decreasing the magnitude θ _x of the optical axis with time that directly affects speckle reduction. The size of the angle range can be expanded. Accordingly, total reflection at the uniformizing optical element 65 is promoted without increasing the length of the uniformizing optical element 65, and the amount of coherent light emitted from each position of the exit surface 65b of the uniformizing optical element 65 is It is possible to effectively equalize, and thereby the illuminated area LZ can be illuminated with uniform illuminance without conspicuous speckles.

  In particular, in the present embodiment, the second diffusing element 60 is configured as a concave lens 61. According to the concave lens 61, the diffusion phenomenon does not occur after focusing once like the convex lens, but the incident light can be diffused immediately after the incident to widen the optical path width. That is, the amount of light emitted from each position on the exit surface 65b of the uniformizing optical element 65 can be uniformized while using the uniformizing optical element 65 having a short length in the light guide direction. Similarly, in the present embodiment, the lens array 51 forming the first diffusing element 50 includes a unit concave lens 52 made of a concave lens as a unit lens. Therefore, the distance between the first diffusing element 50 and the deflecting element 55 can be shortened to reduce the size of the illumination device 40 and the projection device 20.

The distance L _c from the principal point P _mc of the second diffusing element 60 to the incident surface 65 a of the uniformizing optical element 65 is from the principal point P _mb of the deflecting element 55 to the principal point P _mc of the second diffusing element 60. It is shorter than the distance L _b. In other words, the second diffusing element 60 can be disposed away from the deflection element 55 and immediately before the uniformizing optical element 65. Such an arrangement is preferable from the viewpoint of improving the utilization efficiency of light emitted from the irradiation device 70 and from the viewpoint of miniaturization of the device. The “principal point” is the optical center of the lens and is the center point that determines the focal length.

  In FIGS. 1 and 2, the second diffusing element 60 is disposed away from the incident surface 65 a of the homogenizing optical element 65. However, from the viewpoint of improving the utilization efficiency of the light emitted from the irradiation device 70 and from the viewpoint of miniaturization of the device, the second diffusing element 60 comes into contact with the incident surface 65a of the homogenizing optical element 65 and the incident surface. It is preferable to arrange on 65a.

Further, when the second diffusing element 60 is composed of the concave lens 61, the distance L _b from the principal point P _mb of the deflecting element 55 to the principal point P _mc of the second diffusing element 60 is not less than the focal length f _b of the deflecting element 55. Preferably there is. According to such an example, it is possible to prevent the second diffusion element 60 from reducing the magnitude θ _x of the temporal change in the optical axis that directly affects speckle reduction. Can do. That is, the magnitude θ _Z of the temporal change in the optical axis after emission from the second diffusing element 60 is equal to the magnitude θ _{x of the} angular change in the optical axis over time before entering the second diffusing element 60. This is advantageous for speckle reduction.

If the distance L _b from the principal point P _mb of the deflecting element 55 to the principal point P _mc of the second diffusing element 60 is larger than the focal length f _b of the deflecting element 55, the illumination device 40 is increased in size. In consideration of this point, as shown in FIGS. 1 and 2, it is shown that the principal point P _mc of the second diffusing element 60 is located on the rear focal point P _f of the deflecting element 55. This is preferable in terms of both reduction and avoiding the enlargement of the apparatus. When the principal point P _mc of the second diffusing element 60 is located on the rear focal point P _f of the deflecting element 55, the optical axis of the light incident on the second diffusing element 60 at each moment is expressed by the second diffusing element. No turn at 60. Therefore, the expected speckle reduction function can be stably secured. The rear focal point P _f is a focal point located on the outgoing side of the pair of focal points located on both the incident side and the outgoing side of the deflecting element 55. In the present embodiment, the second diffusing element is used. It means the focal point located on the 60 side.

Furthermore, in the embodiment described above, the distance L _a from the incident surface of the first diffusion device 50 until the main point P _mb deflection element 55, a homogenizing optical element 65 from the principal point of the second diffusion element 60 P _mc The distance L _c is longer than the distance L _c to the incident surface 65 a and shorter than the distance L _b from the principal point P _mb of the deflecting element 55 to the principal point P _mc of the second diffusion element 60. As a result, the speckle can be made inconspicuous, and in the useful illumination device 40 that can illuminate the illuminated area LZ with sufficiently uniform illuminance, the device can be sufficiently downsized. .

  Various modifications can be made to the above-described embodiment. Hereinafter, an example of modification will be described with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted.

<First diffusion element>
In the above-described embodiment, the example in which the lens array 51 of the first diffusing element 50 of the optical element 45 includes the unit concave lens 52 made of a concave lens as the unit lens is shown, but the present invention is not limited thereto. As shown in FIG. 4, the lens array 51 of the first diffusing element 50 of the optical element 45 may include a unit convex lens 53 made of a convex lens as a unit lens. In addition, the lens array shown with the dotted line in FIG. 4 has shown arrangement | positioning of the lens array of FIG. 2 including the unit lens which consists of a concave lens. Further, as shown in FIG. 5, the first diffusion element 50 of the optical element 45 may include a hologram recording medium 54.

<Second diffusion element>
In the above-described embodiment, the example in which the second diffusing element 60 is configured as the concave lens 61 is shown, but the present invention is not limited thereto. As an example, as shown in FIG. 4, the second diffusing element 60 may be configured as a convex lens 62.

<Light source device>
Further, in the above-described embodiment, the light source device 71 has the single light source 72. However, the present invention is not limited to this example, and the light source device 71 may include a plurality of light sources. As an example, the light source device 71 may be configured as a laser array including a plurality of laser light sources. The plurality of light sources included in the light source device 71 may generate light in different wavelength bands, or may generate light in the same wavelength band. When a plurality of light sources that generate light of different wavelength bands are used, the illuminated region LZ can be illuminated by light of a color that cannot be generated by a single light source due to additive color mixing. Further, when the plurality of light sources respectively generate red wavelength band light, green wavelength band light, and blue wavelength band light, the illuminated region LZ can be illuminated with white light. On the other hand, when a plurality of light sources that generate light of the same wavelength band are used, the illuminated region LZ can be illuminated with high output.

<Scanning device>
In addition, although the example in which the scanning device 75 is formed as a uniaxial rotation type device that changes the traveling direction of coherent light by reflection has been described, the present invention is not limited to this example. The scanning device 75 can rotate not only about the first rotation axis Ra but also about the second rotation axis that intersects the first rotation axis Ra, so that the reflection surface 76a of the reflection member 76 is centered. It may be. Further, the scanning device 75 may include two or more reflection devices. In this case, even if the reflecting surface of each reflecting device can be rotated only about a single axis, the scanning device 75 uses the scanning path on the first diffusion element 50 as a two-dimensional path. be able to. A specific example of the reflection device included in the scanning device 75 includes a MEMS mirror. The scanning device 75 may include a device other than the reflection device that changes the traveling direction of the coherent light by reflection. For example, the scanning device 75 may include a refractive prism, a lens, and the like.

<Projection device>
Further, in the above-described embodiment, the spatial light modulator 30 is arranged so as to face the emission surface 65b of the uniformizing optical element 65, and the spatial light modulator 30 is illuminated with a uniform light amount. However, the present invention is not limited to this example. For example, as shown in FIG. 6, a relay optical system 35 may be disposed between the homogenizing optical element 65 and the spatial light modulator 30. The position where the spatial light modulator 30 is arranged by the relay optical system 35 is a surface conjugate with the emission surface 65 b of the homogenizing optical element 65. For this reason, also in the example shown in FIG. 6, the spatial light modulator 30 is illuminated with a uniform light amount.

<Other uses>
Further, in the above-described embodiment, the example in which the lighting device 40 is incorporated in the projection device 20 and the projection type video display device 10 has been described. However, the present invention is not limited thereto, and the lighting device 40 may be used for various applications. it can. As an example, the illumination device 40 described above can be used in a scanner illumination device or the like.

<Combination of modification>
In addition, although the some modification with respect to embodiment mentioned above was demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

DESCRIPTION OF SYMBOLS 10 Projection type image display apparatus 15 Screen 20 Projection apparatus 25 Projection optical system 30 Spatial light modulator 35 Relay optical system 40 Illumination apparatus 45 Optical element 50 First diffusion element 51 Lens array 52 Unit concave lens 53 Unit convex lens 54 Hologram recording medium 55 Deflection Element 56 Lens 57 Main point 60 Second diffusing element 61 Concave lens 62 Main point 62 Convex lens 65 Uniform optical element 65a Incident surface 65b Output surface 66 Integrator rod 70 Irradiation device 71 Light source device 72 Light source 75 Scan device 76 Reflective member 76a Reflective surface

Claims (8)

A first diffusing element;
An irradiation device for irradiating the first diffusion element with coherent light so as to scan on the first diffusion element;
A deflection element for changing an optical path of coherent light diffused by the first diffusion element;
A uniformizing optical element through which the coherent light whose optical path has been changed by the deflecting element is reflected, and
A second diffusing element disposed in an optical path from the deflecting element to the homogenizing optical element,
Coherent light that has been incident and diffused on a certain region on the first diffusion element, and coherent light that has been incident and diffused on another region different from the certain region on the first diffusion element are: An illuminating device, wherein each of the illuminating devices is collected in the second diffusing element by the deflecting element, diffused by the second diffusing element, and then used for illumination through the uniformizing optical element.   The lighting device according to claim 1, wherein the second diffusion element includes a concave lens.   The lighting device according to claim 1, wherein the second diffusion element includes a convex lens.   The illuminating device according to any one of claims 1 to 3, wherein the second diffusing element is disposed on an incident surface of the uniformizing optical element.   The illuminating device according to claim 1, wherein a main point of the second diffusing element is located on a rear focal point of the deflecting element.   6. The illumination device according to claim 1, wherein a distance from the second diffusion element to an incident surface of the uniformizing optical element is shorter than a distance from the deflection element to the second diffusion element. .   The lighting device according to claim 1, wherein the first diffusion element has a lens array including a plurality of concave lenses. The lighting device according to any one of claims 1 to 7,
And a spatial light modulator illuminated by light from the illumination device.

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