JP5812390B2 - Illumination device, projection device, and projection-type image display device - Google Patents

Description

  The present invention relates to an illumination device that illuminates an illuminated area with coherent light, a projection device that projects coherent light, and a projection-type image display device that displays an image using coherent light, and in particular, generation of speckle is inconspicuous. The present invention relates to a lighting device, a projection device, and a projection-type image display device that can be made to operate.

  Projection-type image display devices having a screen and a projection device that projects image light on the screen are widely used. In a typical projection-type image display device, an original two-dimensional image is generated by using a spatial light modulator such as a liquid crystal micro display or a DMD (Digital Micromirror Device), and the two-dimensional image is projected into an optical system. An image is displayed on the screen by enlarging and projecting on the screen using the system.

  Various types of projectors have been proposed, including commercially available products called “optical projectors”. In general optical projectors, a spatial light modulator such as a liquid crystal display is illuminated using a lighting device consisting of a white light source such as a high-pressure mercury lamp, and the resulting modulated image is projected onto a screen using a lens. Adopted. For example, in Patent Document 1 below, white light generated by an ultra-high pressure mercury lamp is divided into three primary color components of R, G, and B by a dichroic mirror, and these lights are guided to a spatial light modulator for each primary color. A technique is disclosed in which a generated modulated image for each primary color is synthesized by a cross dichroic prism and projected onto a screen.

  However, high-intensity discharge lamps such as high-pressure mercury lamps have a relatively short life, and when used in optical projectors or the like, it is necessary to frequently replace the lamps. Furthermore, it is not preferable to use a high-pressure mercury lamp that uses mercury from the viewpoint of environmental impact. Further, since it is necessary to use a relatively large optical system such as a dichroic mirror in order to extract the light of each primary color component, there is a problem that the entire apparatus becomes large.

  In order to cope with such a problem, a method using a coherent light source such as a laser has been proposed. For example, a semiconductor laser widely used in the industry has a very long life compared to a high-intensity discharge lamp such as a high-pressure mercury lamp. In addition, since the light source can generate light having a single wavelength, a spectroscopic device such as a dichroic mirror is not necessary, and the entire device can be reduced in size.

  On the other hand, a method using a coherent light source such as a laser beam has a new problem such as generation of speckle. A speckle is a speckled pattern that appears when a scattering surface is irradiated with laser light or other coherent light. When it appears on a screen, it is observed as speckled brightness irregularities (brightness irregularities). It becomes a factor having a physiological adverse effect on the person. The reason why speckles occur when coherent light is used is that coherent light reflected by each part of a scattering reflection surface such as a screen interferes with each other because of its extremely high coherence. . For example, in the following Non-Patent Document 1, detailed theoretical considerations regarding the generation of speckle are made.

  As described above, in the system using the coherent light source, a problem inherent to the generation of speckles occurs, and thus a technique for suppressing the generation of speckles has been proposed. For example, in Patent Document 2 below, the speckle is reduced by irradiating a scattering plate with laser light, guiding the scattered light obtained therefrom to a spatial light modulator, and rotating the scattering plate by a motor. Technology is disclosed.

JP 2004-264512 A Japanese Patent Laid-Open No. 6-208089

Speckle Phenomena in Optics, Joseph W. Goodman, Roberts & Co., 2006

  As described above, technologies for reducing speckles have been proposed in projection devices and projection-type video display devices using a coherent light source. However, the methods proposed so far effectively and sufficiently suppress speckles. I can't do it. For example, in the method disclosed in the above-mentioned Patent Document 2, laser light is irradiated on the scattering plate and scattered, and therefore, part of the laser light is wasted without contributing to video display at all. Moreover, although it is necessary to rotate a scattering plate for speckle reduction, such a mechanical rotation mechanism becomes a comparatively large apparatus, and also power consumption becomes large. Furthermore, even if the scattering plate is rotated, the position of the optical axis of the illumination light does not change, so that speckles generated due to diffusion on the screen cannot be sufficiently suppressed.

  Speckle is not a problem specific to a projection device or a projection type image display device, but is a problem in various devices in which an illumination device that illuminates coherent light in an illuminated area. For example, a scanner that reads image information incorporates an illumination device that illuminates an object to be read. When speckle is generated by the light that illuminates the object to be read, the image information cannot be read accurately. In order to avoid such an inconvenience, a scanner using coherent light needs to perform special processing such as image correction.

  By the way, coherent light, as represented by laser light, can be irradiated as light having excellent straightness and extremely high energy density. Therefore, it is preferable that the light path of the coherent light is designed as an illuminating device actually developed corresponding to the characteristics of the coherent light.

  The inventors of the present invention have made extensive studies based on the above points, and as a result, invented an illuminating device that illuminates an illuminated area with coherent light, which can make speckle inconspicuous. I went to. In addition, the present inventors have further researched and improved the lighting device so that it is possible to stably prevent a bright region from being projected and brightened in the illuminated region illuminated with coherent light. We were able to. That is, the present invention can make speckles inconspicuous and can effectively suppress the occurrence of uneven brightness in the illuminated area, a projection device including the illumination device, and a projection An object of the present invention is to provide a type image display device.

The lighting device according to the present invention comprises:
An optical element capable of diffusing coherent light;
A light deflector provided on the incident side of the optical element, for deflecting and collecting the incident coherent light;
An irradiation device that irradiates the light deflection unit with the coherent light so that coherent light scans the light deflection unit;
The coherent light deflected by the light deflecting unit is guided to the optical element and scanned on the optical element,
The coherent light that is incident and diffused at each position of the optical element illuminates with the illumination regions overlapped with each other.

  In the illumination device according to the present invention, the optical element may be a hologram recording medium.

  In the illumination device according to the present invention, the hologram recording medium may be a transmissive hologram recording medium.

In the lighting device according to the present invention,
The irradiation device, the light deflection unit, and the hologram recording medium are arranged so that the optical path of the 0th-order light of the coherent light incident on each position of the hologram recording medium deviates from the illuminated area. Also good.

  In the illumination device according to the present invention, the optical element may be a lens array that changes a traveling direction of incident light.

  In the illumination device according to the present invention, the optical element may be a diffusion plate that changes a traveling direction of incident light.

In the lighting device according to the present invention,
The irradiation apparatus includes a light source that generates the coherent light, and a scanning device that changes a traveling direction of the coherent light from the light source so that the coherent light scans on the optical deflection unit. May be.

In the lighting device according to the present invention,
The light deflecting unit may be a lens, a prism, a hologram lens, or a diffractive optical element that deflects the traveling direction of the coherent light by refraction or diffraction.

  In the illuminating device according to the present invention, the light deflection section may be integrally provided on the incident-side surface of the optical element.

The projection apparatus according to the present invention
A lighting device according to the invention as described above;
A spatial light modulator illuminated by the illumination device,
The coherent light that has entered and diffused into each incident region of the optical element illuminates the spatial light modulators on top of each other.

In the projection apparatus according to the present invention,
You may further provide the projection optical system which projects the modulation image obtained on the said spatial light modulator on a screen.

A first projection display apparatus according to the present invention is:
A projection device according to the invention as described above;
And a screen on which a modulated image obtained on the spatial light modulator is projected.

A second projection type video display device according to the present invention is:
A lighting device according to the invention as described above;
A screen illuminated by the illumination device,
Coherent light that has been incident and diffused into each incident region of the optical element illuminates with the screens superimposed on each other.

An optical deflecting device according to the present invention comprises:
An optical element capable of diffusing coherent light;
A light deflector provided on the incident side of the optical element, for deflecting and collecting the incident coherent light;
A scanning device that scans coherent light on the light deflection unit, and
The coherent light deflected by the light deflecting unit is guided to the optical element and scanned on the optical element,
The coherent light that is incident and diffused at each position of the optical element illuminates with the illumination regions overlapped with each other.

  ADVANTAGE OF THE INVENTION According to this invention, the speckle on the to-be-illuminated area | region or the surface which projects an image | video can be made effectively inconspicuous.

FIG. 1 is a diagram for explaining a basic form of an embodiment according to the present invention, and shows a schematic configuration of a lighting device, a projection apparatus, and a projection type video display apparatus as one specific example of the basic form. FIG. FIG. 2 is a diagram illustrating the illumination device illustrated in FIG. 1. FIG. 3 is a diagram for explaining an exposure method for producing a hologram recording medium that forms an optical element of the illumination device of FIG. FIG. 4 is a diagram for explaining the operation of the hologram recording medium manufactured through the exposure method of FIG. FIG. 5 is a perspective view for explaining the operation of the lighting apparatus shown in FIG. FIG. 6 is a diagram corresponding to FIG. 2, and is a diagram illustrating a relationship between the reproduction light in the comparative example, the reproduction light in the basic form, and the reproduction illumination light in the comparative example and the basic form. FIG. 7 is a diagram for explaining a modification of the optical element, and is a plan view showing the optical element together with a corresponding illuminated region. FIG. 8 is a diagram for explaining another modification of the optical element, and is a plan view showing the optical element together with a corresponding illuminated region. FIG. 9 is a diagram corresponding to FIG. 5, and is a perspective view for explaining a modification of the irradiation apparatus and its operation.

  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.

  The illumination device, the projection device, and the projection-type image display device according to an embodiment of the present invention have a configuration that can effectively prevent speckle as a basic configuration.

  FIGS. 1-9 is a figure for demonstrating the illuminating device which concerns on one embodiment of this invention, a projection apparatus, a projection type video display apparatus, and its modification. Among these, with reference to FIGS. 1-6, the illuminating device, projection apparatus, and projection type video display apparatus which concern on the basic form of one Embodiment are demonstrated. Then, an example of the modification with respect to the illuminating device which concerns on a basic form, a projection apparatus, and a projection type video display apparatus is demonstrated.

<Basic form>
[Configuration of basic form]
First, the configuration of a projection-type image display device that includes an illumination device that projects coherent light and a projection device and can make speckles inconspicuous will be described mainly with reference to FIGS.

  A projection video display device 10 shown in FIG. 1 includes a screen 15 and a projection device 20 that projects video light including coherent light. The projection device 20 includes an illuminating device 40 that illuminates the illuminated region LZ located on the virtual plane with coherent light, and a spatial light modulator that is disposed at a position overlapping the illuminated region LZ and that is illuminated with the coherent light by the illuminating device 40. 30 and a projection optical system 25 that projects the coherent light from the spatial light modulator 30 onto the screen 15.

  As the spatial light modulator 30, for example, a transmissive liquid crystal microdisplay can be used. In this case, the spatial light modulator 30 illuminated in a planar shape by the illumination device 40 selects and transmits coherent light for each pixel, thereby forming a modulated image on the screen of the display that forms the spatial light modulator 30. Will come to be. The modulated image (video light) thus obtained is projected onto the screen 15 at the same magnification or scaled by the projection optical system 25. As a result, the modulated image is displayed on the screen 15 at the same magnification or at a variable magnification, usually enlarged, and the observer can observe the image.

  As the spatial light modulator 30, a reflective micro display can be used. In this case, a modulated image is formed by the reflected light from the spatial light modulator 30, the surface on which the spatial light modulator 30 is irradiated with coherent light from the illumination device 40, and the image light that forms the modulated image from the spatial light modulator 30. The surface where the lead is the same surface. When such reflected light is used, a MEMS element such as a DMD (Digital Micromirror Device) can be used as the spatial light modulator 30. In the apparatus disclosed in Patent Document 2 described above, DMD is used as a spatial light modulator.

  Moreover, 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 the coherent light by the illumination device 40. In this case, it is because the coherent light from the illuminating device 40 can be used with high utilization efficiency for displaying the image on the screen 15.

  The screen 15 may be configured as a transmissive screen or may be configured as a reflective screen. In the case where the screen 15 is configured as a reflective screen, the observer observes an image displayed by coherent light reflected by the screen 15 from the same side as the projection device 20 with respect to the screen 15. On the other hand, when the screen 15 is configured as a transmissive screen, the observer observes an image displayed by coherent light transmitted through the screen 15 from the side opposite to the projection device 20 with respect to the screen 15. .

  By the way, the coherent light projected on the screen 15 is diffused and recognized as an image by the observer. At this time, the coherent light projected on the screen interferes by diffusion and causes speckle. However, in the projection display apparatus 10 described here, the illumination apparatus 40 described below illuminates the illuminated area LZ on which the spatial light modulator 30 is superimposed with coherent light that changes in angle with time. It is like that. More specifically, the illuminating device 40 described below illuminates the illuminated region LZ with diffused light composed of coherent light, and the incident angle of this diffused light changes over time. As a result, the diffusion pattern of the coherent light on the screen 15 also changes with time, and speckles generated by the diffusion of the coherent light are temporally superimposed and become inconspicuous. Hereinafter, such an illuminating device 40 will be described in more detail.

  The illuminating device 40 shown in FIGS. 1 and 2 includes an optical element 50 that diffuses coherent light and directs the traveling direction of the coherent light toward the illuminated region LZ, and is provided on the incident side of the optical element 50. The light deflecting unit 70 deflects and collects the light, and the irradiation device 60 that irradiates the light deflecting unit 70 with coherent light. The optical element 50 is capable of diffusing coherent light with respect to at least the entire illuminated area LZ at each point. The optical element 50 includes a hologram recording medium 55 that can reproduce the image 5 of the scattering plate 6. In the illustrated example, the optical element 50 is formed from a hologram recording medium 55. The light deflection unit 70 is integrally provided on the incident side surface of the hologram recording medium 55. However, the light deflection unit 70 and the hologram recording medium 55 may be arranged separately. Specific examples of the light deflection unit 70 include a resin or glass lens, a Fresnel lens, a prism, a hologram lens, a diffractive optical element (DOE), and the like.

  The irradiation device 60 irradiates the light deflection unit 70 with coherent light so that the coherent light scans on the light deflection unit 70. The light deflecting unit 70 deflects the incident coherent light by refraction or diffraction, and condenses it toward the focal point FP located on the exit side of the hologram recording medium 55. Thereby, the coherent light deflected by the light deflecting unit 70 is guided to the optical element 50 and scans on the hologram recording medium 55 of the optical element 50. Therefore, a region on the hologram recording medium 55 that is irradiated with coherent light at a certain moment is a part of the surface of the hologram recording medium 55, and in particular, in the illustrated example, is a minute region that should be called a point. .

  The hologram recording medium 55 constituting the optical element 50 in the illustrated example can receive the coherent light deflected by the light deflecting unit 70 as the reproduction illumination light La, and can diffract the coherent light with high efficiency. In particular, the hologram recording medium 55 can reproduce the image 5 of the scattering plate 6 by diffracting coherent light incident on each position, in other words, each minute region that should be called each point. ing.

  Then, the coherent light that is deflected by the light deflection unit 70 and scans on the hologram recording medium 55 is located at each position (each point or each region (hereinafter the same)) on the hologram recording medium 55. Incident light is incident at an incident angle that satisfies the diffraction conditions. In particular, as shown in FIG. 2, the coherent light incident on each position of the hologram recording medium 55 from the light deflection unit 70 is superimposed on the illuminated region LZ to reproduce the image 5 of the scattering plate 6. Yes. That is, the coherent light incident on each position of the hologram recording medium 55 is diffused by the optical element 50 and enters the illuminated area LZ. That is, when considered on a virtual surface located closer to the hologram recording medium 55 than the illuminated region LZ, the coherent light incident and diffracted at each position of the hologram recording medium 55 illuminates the corresponding region on the virtual surface. In addition, the regions on the virtual surface overlap each other at least partially.

  In the example shown in the figure, a transmissive relief type (embossed type) hologram is used as the hologram recording medium 55 that enables such a coherent light diffraction effect. As shown in FIG. 3, the hologram recording medium 55 is manufactured by using the scattered light from the actual scattering plate 6 as the object light Lo. FIG. 3 shows a state in which the hologram photosensitive material 58 having photosensitivity that forms the hologram recording medium 55 is exposed to the reference light Lr and the object light Lo, which are coherent light beams having coherence with each other. ,It is shown.

  As the reference light Lr, for example, laser light from a laser light source that oscillates laser light in a specific wavelength region is used, and is incident on the hologram photosensitive material 58. In the example shown in FIG. 3, the reference light Lr enters the hologram photosensitive material 58 as a divergent light beam from the reference point SP.

  Next, the object light Lo is incident on the hologram photosensitive material 58 as scattered light from a scattering plate 6 made of, for example, opal glass. Here, since the hologram recording medium 55 to be manufactured is a transmission type, the object light Lo enters the hologram photosensitive material 58 from the same surface as the reference light Lr. The object light Lo needs to have coherency with the reference light Lr. Therefore, for example, laser light oscillated from the same laser light source can be divided, and one of the divided lights can be used as the reference light Lr and the other can be used as the object light Lo.

  In the example shown in FIG. 3, a parallel light beam parallel to the normal direction to the plate surface of the scattering plate 6 is incident on and scattered by the scattering plate 6, and the scattered light transmitted through the scattering plate 6 is the object light Lo. The light enters the hologram photosensitive material 58. According to this method, when an isotropic scattering plate that is usually available at a low cost is used as the scattering plate 6, the object light Lo from the scattering plate 6 is incident on the hologram photosensitive material 58 with a substantially uniform light amount distribution. Is possible. Further, according to this method, although depending on the degree of scattering by the scattering plate 6, the object light Lo is incident on each position of the hologram photosensitive material 58 with a substantially uniform light amount from the entire area of the exit surface 6 a of the scattering plate 6. It becomes easy. In such a case, the light incident on each position of the obtained hologram recording medium 55 reproduces the image 5 of the scattering plate 6 with the same brightness, and the reproduced scattering plate 6 It can be realized that the image 5 is observed with substantially uniform brightness.

  As described above, when the hologram recording material 58 is exposed to the reference light Lr and the object light Lo, an interference fringe formed by the interference of the reference light Lr and the object light Lo is generated. A dimensional pattern is recorded on one surface of the hologram recording material 58. Thereafter, appropriate post-processing corresponding to the type of the hologram recording material 58 is performed, and the hologram recording material 55 in which the interference fringes are converted into a two-dimensional pattern composed of irregularities is obtained.

  FIG. 4 shows the diffraction action (reproduction action) of the hologram recording medium 55 obtained through the exposure process of FIG. As shown in FIG. 4, the hologram recording medium 55 formed from the hologram photosensitive material 58 of FIG. 3 is light having the same wavelength as the laser beam used in the exposure process, and the optical path of the reference light Lr in the exposure process. The light traveling in the opposite direction satisfies the diffraction condition. That is, as shown in FIG. 4, the focal point FP positioned with respect to the hologram recording medium 55 in the same positional relationship as the relative position of the reference point SP (see FIG. 3) with respect to the hologram photosensitive material 58 during the exposure process. The converging light beam that converges toward the light source and has the same wavelength as the reference light Lr in the exposure process is diffracted as the reproduction illumination light La to the hologram recording medium 55, and the diffusing plate 6 with respect to the hologram photosensitive material 58 in the exposure process The reproduced image 5 of the scattering plate 6 is generated at a specific position with respect to the hologram recording medium 50 that has the same positional relationship as the relative position (see FIG. 3).

  At this time, the reproduction light Lb for generating the reproduction image 5 of the scattering plate 6, that is, the light formed by diffracting the reproduction illumination light La by the hologram recording medium 55 travels from the scattering plate 6 toward the hologram photosensitive material 58 during the exposure process. Each point of the image 5 of the scattering plate 6 is reproduced as light traveling in the opposite direction along the optical path of the object light Lo that has been emitted. As described above and as shown in FIG. 3, the scattered light Lo emitted from each position on the exit surface 6 a of the scattering plate 6 in the exposure process is incident on almost the entire region of the hologram photosensitive material 58. Has spread. That is, the object light Lo from the entire area of the exit surface 6 a of the scattering plate 6 is incident on each position on the hologram photosensitive material 58, and as a result, information on the entire exit surface 6 a is placed on each position of the hologram recording medium 55. Each is recorded. Therefore, each of the lights forming the convergent light beam to the focal point FP functioning as the reproduction illumination light La shown in FIG. 4 is incident on each position of the hologram recording medium 55 and has the same contour. The scattered image 6 of the scattering plate 6 can be reproduced at the same position (illuminated area LZ).

  On the other hand, the irradiation device 60 that irradiates the light deflection unit 70 with coherent light can be configured as follows. In the example shown in FIGS. 1 and 2, the irradiation device 60 includes a laser light source 61a that generates coherent light in a specific wavelength range, and a scanning device 65 that changes the traveling direction of the coherent light from the laser light source 61a. Have. The scanning device 65 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 scanning device 65 scans on the light deflection unit 70.

  In particular, in the example shown in FIG. 2, the scanning device 65 includes a reflective device 66 having a reflective surface 66a that can be rotated about one axis RA1. More specifically, the reflection device 66 is configured as a mirror device having a mirror as a reflection surface 66a that can be rotated about one axis RA1. As shown in FIGS. 2 and 5, the mirror device 66 changes the traveling direction of coherent light from the laser light source 61a by changing the orientation of the reflecting surface 66a. At this time, as shown in FIG. 2, the mirror device 66 receives the coherent light from the laser light source 61a at a certain position (hereinafter also referred to as “reference position”) RP. For this reason, the coherent light is changed in the traveling direction by the mirror device 66 that periodically rotates within a predetermined angle range, and then travels along the optical path of the light beam that forms the divergent light beam that diverges from the reference position RP. Become.

  Further, as described above, the light deflection unit 70 in the present embodiment is configured to deflect and collect the divergent light beam that diverges from the reference position RP and convert it into a convergent light beam that converges at the focal point FP. ing. For this reason, the coherent light whose optical path is adjusted by the light deflecting unit 70 can be incident on the hologram recording medium 55 of the optical element 50 as the reproduction illumination light La that forms one light beam of the convergent light beam that converges at the focal point FP. As a result, the coherent light scans on the hologram recording medium 55, and the coherent light incident on each position on the hologram recording medium 55 forms an image of the scattering plate 6 having the same contour at the same position ( It is reproduced in the illuminated area LZ).

  FIG. 5 shows a perspective view of the configuration of the illumination device 40 shown in FIG. The mirror device 66 shown in FIGS. 2 and 5 is configured to rotate the reflecting surface 66a along one axis line RA1. For this reason, the incident point IP1 of the coherent light whose traveling direction is continuously changed by the mirror device 66 to the optical deflection unit 70 is reciprocated along the linear scanning path PW1 on the incident surface of the optical deflection unit 70. Become. In particular, in the example shown in FIG. 5, the rotation axis RA1 of the mirror device 66 has an XY coordinate system defined on the plate surface of the hologram recording medium 55, that is, the XY plane is parallel to the plate surface of the hologram recording medium 55. It extends parallel to the Y axis of the XY coordinate system. The reflection surface 66a is deflected by the light deflecting unit 70 by periodically rotating about an axis line RA1 parallel to the Y axis of the XY coordinate system defined on the plate surface of the hologram recording medium 55. The incident point IP <b> 2 of the coherent light on the optical element 50 is reciprocated in a direction parallel to the X axis of the XY coordinate system defined on the plate surface of the hologram recording medium 55. In other words, in the example shown in FIG. 5, the irradiation device 60 is coherent to the light deflection unit 70 so that the coherent light deflected by the light deflection unit 70 scans on the hologram recording medium 55 along the linear path PW2. Irradiate light. In this specification, a combination of the optical element 50, the light deflecting unit 70, and the scanning device 65 is referred to as an optical deflecting device.

  As a practical problem, the hologram recording material 58 may shrink when the hologram recording medium 55 is produced. In such a case, it is preferable to adjust the incident / exit angle of the coherent light irradiated from the irradiation device 60 to the optical element 50 in consideration of the shrinkage of the hologram recording material 58. Therefore, the wavelength of the coherent light generated by the coherent light source 61a does not need to be exactly the same as the wavelength of the light used in the exposure process (recording process) in FIG. 3, and may be substantially the same.

  For the same reason, even if the traveling direction of the light incident on the hologram recording medium 55 of the optical element 50 does not take exactly the same path as the one light beam included in the convergent light beam to the focal point FP, The image 5 can be reproduced on the LZ. Actually, in the example shown in FIGS. 2 and 5, the reflecting surface 66a of the mirror device 66 constituting the scanning device 65 is inevitably deviated from the rotation axis RA1. Therefore, when the reflecting surface 66a is rotated around the rotation axis RA1 that does not pass through the reference position RP, the coherent light traveling from the mirror device 66 to the light deflecting unit 70 is divergence from the reference position RP in a strict sense. As a result, the light that is deflected by the light deflecting unit 70 and incident on the hologram recording medium 55 may not be a single light beam included in the convergent light beam at the focal point FP. . However, in practice, the image 5 can be substantially reproduced by being superimposed on the illuminated region LZ by coherent light from the irradiation device 60 having the illustrated configuration.

  By the way, a part of the coherent light from the irradiation device 60 is so-called zero-order light that passes through the hologram recording medium 55 without being diffracted by the hologram recording medium 55. When the zero-order light transmitted through the optical element 50 is incident on the illuminated area LZ for some reason, a point area or a linear area where the brightness (luminance) increases sharply compared to the surrounding area. An abnormal region such as a planar region is generated in the illuminated region LZ.

  In this basic form, 0 of the coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 via the light deflection unit 70 is transmitted through the hologram recording medium 55 without being diffracted by the hologram recording medium 55. The irradiation device 60, the light deflection unit 70, and the optical element 50 are arranged so that the optical path of the next light L101 deviates from the illuminated region LZ. That is, the 0th-order light L101 out of the coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 via the light deflection unit 70 does not directly enter the illuminated area LZ. Thereby, it is possible to prevent an abnormal region such as a dotted region, a linear region, or a planar region where the brightness (luminance) increases sharply compared with the surroundings from occurring in the illuminated region LZ, The in-plane distribution of brightness can be made uniform. Moreover, in the projection apparatus 20 and the projection type video display apparatus 10, it is possible to display a scheduled video with high quality. Furthermore, when a laser light source that oscillates a laser beam having a high energy density is used as the light source of the irradiation device 60, it is very preferable in terms of safety. As described above, when considering a virtual surface located on the hologram recording medium 55 side from the illuminated region LZ, the optical path of the 0th-order light L101 is deviated from each region on the virtual surface illuminated with coherent light. It has become.

[Effects of basic form]
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 60 irradiates the optical deflection unit 70 with coherent light so that the coherent light scans the optical deflection unit 70. Specifically, coherent light having a specific wavelength traveling along a certain direction is generated by the laser light source 61 a, and the traveling direction of the coherent light is changed by the scanning device 65. The traveling direction of the coherent light whose traveling direction has been changed can be further changed by the optical deflection unit 70 so as to be directed to the focal point FP on the emission side of the hologram recording medium 55. Accordingly, the scanning device 65 causes the coherent light having a specific wavelength to enter each position on the hologram recording medium 55 through the light deflecting unit 70 at an incident angle that satisfies the Bragg condition at the position. As a result, the coherent light incident at each position is superimposed on the illuminated region LZ by the diffraction at the hologram recording medium 55 to reproduce the image 5 of the scattering plate 6. That is, the coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 via the light deflecting unit 70 is diffused by the optical element 50 and enters the entire illuminated area LZ. Thus, the illuminating device 40 comes to illuminate the illuminated area LZ 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. However, at this time, the coherent light projected on the screen interferes by diffusion and causes speckle.

  However, according to the lighting device 40 in the basic mode described here, speckles can be made extremely inconspicuous as described below.

  According to the aforementioned Non-Patent Document 1, it is effective to multiplex parameters such as polarization, phase, angle, and time and increase the mode in order to make speckle inconspicuous. 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 by dividing the time, the mode is the same as the number of times the incident direction of the coherent light has changed during the 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 irradiation device 60 described above, the coherent light is irradiated onto the light deflection unit 70 so as to scan the light deflection unit 70. Thereby, the coherent light deflected by the light deflecting unit 70 scans on the hologram recording medium 55. The coherent light incident on each position of the hologram recording medium 55 from the light deflection unit 70 illuminates the entire illuminated area LZ with coherent light, but the illumination direction of the coherent light that illuminates the illuminated area LZ Are different from each other. Since the position on the hologram recording medium 55 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 position in the illuminated area LZ, but the incident direction constantly changes as indicated 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 the optical path over time as indicated by an arrow A2 in FIG. Will come to be.

  The coherent light continuously scans on the hologram recording medium 55. Accordingly, the incident direction of coherent light from the illumination device 40 to the illuminated region LZ also changes continuously, and the incident direction of coherent light from the projection device 20 to the screen 15 also changes continuously. Here, if the incident direction of the coherent light from the projection device 20 to the screen 15 changes only slightly (for example, several degrees), the speckle pattern generated on the screen 15 also changes greatly, and an uncorrelated speckle pattern. Are sufficiently superimposed. In addition, the frequency of scanning devices 65 such as MEMS mirrors and polygon mirrors that are commercially available is usually several hundred Hz or higher, and scanning devices 65 that reach tens of thousands of Hz are not uncommon.

  From the above, according to the basic form described above, the incident direction of the coherent light changes temporally at each position on the screen 15 displaying an image, and this change is caused by human eyes. As a result, a non-correlated coherent light scattering pattern is multiplexed and observed by 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 basic mode described above, the coherent light continuously scans on the hologram recording medium 55, and the coherent light incident on each position of the hologram recording medium 55 is superimposed on the spatial light modulator 30, respectively. The entire illuminated area LZ is illuminated. That is, the hologram recording medium 55 forms a new wavefront that is separate from the wavefront used to form the speckle pattern, and the illumination area LZ and further the spatial light modulator 30 are formed in a complex and uniform manner. Through this, the screen 15 is illuminated. Due to the formation of a new wavefront on the hologram recording medium 55, the speckle pattern generated on the projection apparatus side is made invisible.

  By the way, Non-Patent Document 1 described above proposes a method using a numerical value called speckle contrast (unit%) as a parameter indicating the degree of speckle generated on the screen. This speckle contrast is defined as a value obtained by dividing the standard deviation of the actual luminance variation on the screen divided by the average luminance value when displaying a test pattern image that should have a uniform luminance distribution. Amount. The larger the speckle contrast value is, the larger the speckle occurrence level on the screen is, which indicates that the spot-like luminance unevenness pattern is more prominently presented to the observer.

  When the speckle contrast is measured for the projection-type image display device 10 of the basic form described with reference to FIGS. 1 to 5, the optical element 50 is a scattering plate when receiving specific reproduction illumination light. The speckle contrast in the case of using a relief hologram as a computer-generated hologram (CGH) having a concavo-convex shape designed using a computer so that the image 5 of 6 can be reproduced is 3.7% ( Condition 1). In HDTV (high-definition television) video display applications, a speckle contrast of 6.0% or less is a standard (for example, WO / 2001/081996) as a level at which an uneven brightness pattern is hardly recognized when an observer observes with the naked eye. The basic form described above sufficiently satisfies this standard. In addition, when actually observed with the naked eye, brightness unevenness (brightness unevenness) that could be visually recognized did not occur.

  On the other hand, when the laser light from the laser light source is shaped into a parallel light beam and incident on the spatial light modulator 30, that is, the spatial light modulator 30 of the projection display apparatus 10 shown in FIG. 65, when the coherent light from the laser light source 61a is incident as a parallel light beam without passing through the light deflecting unit 70 and the optical element 50, the speckle contrast is 20.7% (condition 2). Under these conditions, a spot-like luminance unevenness pattern was observed quite noticeably by visual observation.

  Further, when the light source 61a is replaced with a green LED (non-coherent light source) and light from the LED light source is incident on the spatial light modulator 30, that is, the projection type video display device 10 shown in FIG. When the non-coherent light from the LED light source is incident on the spatial light modulator 30 as a parallel light beam without passing through the scanning device 65, the light deflecting unit 70, and the optical element 50, the speckle contrast is 4.0%. (Condition 3). Under these conditions, brightness unevenness (brightness unevenness) that could be visually recognized by naked eye observation did not occur.

  The result of condition 1 was much better than the result of condition 2, and further better than the measurement result of condition 3. As already mentioned, the problem of speckle generation is a problem inherent in the case of using a coherent light source such as a laser beam in practice, and it is necessary to consider in an apparatus using a non-coherent light source such as an LED. There is no problem. In addition, in the condition 1, an optical element 50 that can cause speckles is added as compared with the condition 3. From these points, it can be said that according to the condition 1, it was possible to sufficiently cope with the speckle defect.

  In addition, according to the basic mode described above, the following advantages can be obtained.

  According to the basic form described above, the change in the angle of the traveling direction of coherent light due to diffraction in the hologram recording medium 55 can be minimized. Thereby, the light use efficiency in the hologram recording medium 55 can be improved.

  This will be described in more detail. In the relief-type hologram recording medium 55, interference fringes are recorded by the uneven structure on the surface. The hologram recording medium 55 can form an image of the scattering plate at a predetermined position by the first-order diffracted light diffracted by the uneven structure. Therefore, depending on the incident angle of the coherent light to the hologram recording medium 55 and the emission angle of the coherent light from the hologram recording medium 55, the diffraction efficiency in the hologram recording medium 55 is low, or a large amount of light is taken as high-order light. Problem arises. For example, when the incident angle is large or the emission angle is large, the angle change in the traveling direction of the coherent light due to diffraction in the hologram recording medium 55 becomes large, and thus the above problem occurs. As a result, the amount of incident coherent light is greatly lost.

  Here, as a comparative example, a case is considered where the light deflection unit 70 is removed from the configuration of the basic form of FIG. 1 and coherent light (reproduction light) is directly incident on the hologram recording medium 55 from the irradiation device 60. FIG. 6 shows the reproduction light Lc in the comparative example, the reproduction light La deflected by the light deflecting unit 70 in the basic form, and the reproduction illumination light Lb in the comparative example and the basic form. FIG. 6 shows the reproduction light Lc and reproduction light La incident on the hologram recording medium 55 at the maximum incident angle, and the reproduction light Lc and reproduction light La are diffracted and emitted from the hologram recording medium 55 at the maximum emission angle. The reproduction illumination light Lb to be performed is shown. As shown in FIG. 6, in order to obtain the same reproduction illumination light Lb, the angle change (θc) in the traveling direction of the coherent light due to diffraction in the comparative example is the angle change (θc) in the traveling direction of the coherent light in the basic form ( larger than θ1). Therefore, in the comparative example, as described above, the amount of incident coherent light is greatly lost. On the other hand, as described above, according to the basic mode, the traveling direction of the coherent light is deflected by the light deflecting unit 70 and is incident on the hologram recording medium 55. The angle change in the traveling direction of the coherent light can be minimized, and such a problem can be solved.

  Further, according to the basic form described above, the optical element 50 for making speckles inconspicuous can also function as an optical member for shaping and adjusting the beam form of coherent light emitted from the irradiation device 60. . Therefore, the optical system can be reduced in size and simplified.

  Further, according to the basic form described above, coherent light incident on each position of the hologram recording medium 55 generates an image 5 of the scattering plate 6 at the same position, and is superimposed on the image 5 to generate spatial light. A modulator 30 is arranged. Therefore, the light diffracted by the hologram recording medium 55 can be used for image formation with high efficiency, and the use efficiency of light from the light source 61a is excellent.

[Deformation to basic form]
Various modifications can be made to the basic form described based on one specific example illustrated in FIGS. Hereinafter, an example of modification will be described with reference to the drawings. In the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above-described embodiment are used, and redundant descriptions are omitted.

(Light deflection part)
In the basic mode, the light deflecting unit 70 has described an example of collecting the incident coherent light toward the focal point FP located on the emission side of the hologram recording medium 55, but the present invention is not limited thereto. For example, the light deflection unit 70 can deflect and collect a divergent light beam that diverges from the reference position RP at the first divergence angle, and can convert it into a divergent light beam having a second divergence angle smaller than the first divergence angle. It may be a thing. In this case, the coherent light incident on the optical deflecting unit 70 at a certain incident angle is deflected, and the deflected coherent light is incident on the hologram recording medium 55 at an incident angle smaller than the incident angle. Accordingly, the angle change in the traveling direction of the coherent light due to diffraction in the hologram recording medium 55 can be made smaller than when the light deflection unit 70 is not used. The light deflecting unit 70 may be configured to deflect and collect a divergent light beam that diverges from the reference position RP and convert it into a parallel light beam.

(Projection device)
In the basic mode, an example in which the spatial light modulator 30 is disposed at a position overlapping the illuminated region LZ has been described, but the spatial light modulator 30 may not be disposed at a position strictly overlapping the illuminated region LZ. . For example, in the configuration of FIG. 1, the spatial light modulator 30 may be disposed closer to the optical element 50 than the illuminated region LZ, or may be disposed closer to the projection optical system 25 than the illuminated region LZ. That is, the optical element 50 and the spatial light modulator 30 need only be arranged so that the coherent light that has entered and diffused at each position of the optical element 50 illuminates the spatial light modulator 30 in an overlapping manner.

(Lighting device)
According to the embodiment described above, speckle can be effectively made inconspicuous. However, this effect is mainly due to the lighting device 40. Therefore, the lighting device 40 can be usefully used in various aspects. For example, the illumination device 40 can be used as simple illumination. In this case, brightness unevenness such as brightness unevenness and flickering can be made inconspicuous.

  Moreover, you may use the illuminating device 40 mentioned above as illumination for an image reading apparatus as an example. In such an example, the speckle generated on the target object can be made inconspicuous by arranging the target object to be scanned on the illuminated region LZ of the lighting device 40. As a result, it is possible to eliminate image correction means and the like that are conventionally required.

  When the illuminating device 40 is incorporated in a scanner, the illuminated area LZ by the illuminating device 40 may be a surface as in the above-described form. Alternatively, the illuminated area LZ by the illumination device 40 may be an elongated area extending in one direction, that is, an area called a linear shape. In this case, two-dimensional image information can be read by the illuminating device 40 incorporated in the scanner moving relative to the object along a direction orthogonal to the one direction.

  Furthermore, as shown in FIG. 7, the optical element 50 may include a plurality of hologram recording media 55-1, 55-2,... Arranged side by side so as not to overlap. Each of the hologram recording media 55-1, 55-2,... Shown in FIG. 7 is formed in a strip shape, and is arranged side by side with no gap in a direction orthogonal to the longitudinal direction. Further, the hologram recording media 55-1, 55-2,... Are located on the same virtual plane. Each hologram recording medium 55-1, 55-2,... Has an image 5 of the scattering plate 6 in the illuminated areas LZ-1, LZ-2,. Generate, in other words, illuminate the illuminated areas LZ-1, LZ-2,... With coherent light. Each of the illuminated areas LZ-1, LZ-2,... Is formed as an elongated area extending in one direction, that is, an area called a linear shape, and arranged side by side in a direction perpendicular to the longitudinal direction without any gap. ing. In addition, each of the illuminated areas LZ-1, LZ-2,... Is located on the same virtual plane.

  In the example shown in FIG. 7, the illuminated areas LZ-1, LZ-2,... May be illuminated as follows. First, the irradiation device 60 is configured so that the coherent light deflected by the light deflection unit 70 repeatedly scans the path PW2 along the longitudinal direction (the one direction) of the first hologram recording medium 55-1. 70 is irradiated with coherent light. The coherent light incident on each position of the first hologram recording medium 55-1 is superimposed on the first illumination area LZ-1 to reproduce the image 5 of the linear or elongated scattering plate 6, and the first One illumination area LZ-1 is illuminated with coherent light. When a predetermined time elapses, the irradiation device 60 scans the second hologram recording medium 55-2 adjacent to the first hologram recording medium 55-1 with the coherent light deflected by the light deflecting unit 70. The light deflecting unit 70 is irradiated with coherent light, and the second illuminated area LZ-2 adjacent to the first illuminated area LZ-1 is replaced with the coherent light instead of the first illuminated area LZ-1. Illuminate. Hereinafter, the hologram recording medium is sequentially irradiated with coherent light, and the illuminated area corresponding to the hologram recording medium is illuminated with the coherent light. According to such a method, it is possible to read two-dimensional image information without moving the illumination device.

(Spatial light modulator, projection optical system, screen)
According to the embodiment described above, speckle can be effectively made inconspicuous. However, this effect is mainly due to the lighting device 40. Even if this lighting device 40 is combined with various known spatial light modulators, projection optical systems, screens, etc., speckles can be effectively made inconspicuous. From this point, the spatial light modulator, the projection optical system, and the screen are not limited to those illustrated, and various known members, components, devices, and the like can be used.

(Projection-type image display device)
Moreover, although the example in which the hologram recording medium 55 is manufactured by the interference exposure method using the planar scattering plate 6 having a shape corresponding to the incident surface of the spatial light modulator 30 is shown, the present invention is not limited thereto. The hologram recording medium 55 may be manufactured by an interference exposure method using a scattering plate having a certain pattern. In this case, the image of the scattering plate having a certain pattern is reproduced by the hologram recording medium 55. In other words, the optical element 50 (hologram recording medium 55) illuminates the illuminated area LZ having a certain pattern. When this optical element 50 is used, the spatial light modulator 30 and the projection optical system 25 are also omitted from the basic form described above, and the screen 15 is disposed on the screen 15 by overlapping with the illuminated region LZ. Any pattern recorded on the hologram recording medium 55 can be displayed. Also in this display device, the irradiation device 60 irradiates the light deflection unit 70 with the coherent light so that the coherent light deflected by the light deflection unit 70 scans on the hologram recording medium 55, so that Speckle can be made inconspicuous.

  FIG. 8 discloses an example of such an example. In the illustrated example, the optical element 50 includes first to third hologram recording media 55-1, 55-2, and 55-3. The first to third hologram recording media 55-1, 55-2, and 55-3 are arranged on surfaces parallel to the incident surface of the optical element 50 so as not to overlap each other. Each of the hologram recording media 55-1, 55-2, 55-3 can reproduce the image 5 having the outline of the arrow, in other words, the illuminated areas LZ-1, LZ- having the outline of the arrow. 2 and LZ-3 can be illuminated with coherent light. The first to third illuminated areas LZ-1, LZ-2, and LZ-3 respectively corresponding to the hologram recording media 55-1, 55-2, and 55-3 overlap each other on the same virtual plane. It is arranged not to become. In particular, in the illustrated example, the directions indicated by the arrows forming the illuminated areas LZ-1, LZ-2, and LZ-3 are all the same, and the first to third illuminated areas LZ-1, LZ-2 and LZ-3 are positioned in this order. For example, when the coherent light from the light deflection unit 70 is scanned on the first hologram recording medium 55-1, the first illuminated region LZ-1 located at the rearmost position is illuminated. As an example, next, as shown in FIG. 8, the coherent light from the light deflecting unit 70 scans over the second hologram recording medium 55-2, and the second illuminated area LZ-2 located in the middle. Is illuminated. Thereafter, when the coherent light from the light deflection unit 70 scans on the third hologram recording medium 55-3, the third illuminated area LZ-3 located in the forefront is illuminated.

(Irradiation device)
In the embodiment described above, an example in which the irradiation device 60 includes the laser light source 61a and the scanning device 65 has been described. Although the scanning device 65 is an example of the uniaxial rotation type mirror device 66 that changes the traveling direction of the coherent light by reflection, the scanning device 65 is not limited thereto. As shown in FIG. 9, the scanning device 65 includes not only the first rotation axis RA1 but also the second rotation axis RA2 where the reflection surface 66a of the mirror device 66 intersects the first rotation axis RA1. The center may be rotatable. In the example shown in FIG. 9, the second rotation axis RA2 of the reflecting surface 66a is a first rotation axis RA1 extending in parallel with the Y axis of the XY coordinate system defined on the plate surface of the hologram recording medium 55. And they are orthogonal. Since the reflecting surface 66a is rotatable about both the first axis RA1 and the second axis RA2, the incident point IP1 of the coherent light from the irradiation device 60 on the surface of the light deflection unit 70 is two-dimensional. It can move in the direction. As a result, the incident point IP <b> 2 of the coherent light deflected by the light deflecting unit 70 to the optical element 50 can be moved in a two-dimensional direction on the plate surface of the hologram recording medium 55. As an example, as shown in FIG. 9, the incident point IP1 of the coherent light to the light deflecting unit 70 may be moved on the circumferential scanning path PW1, thereby to the optical element 50 of the coherent light. The incident point IP2 can be moved on the circumferential scanning path PW2.

  Further, the scanning device 65 may include two or more mirror devices 66. In this case, even if the reflection surface 66a of the mirror device 66 is rotatable only about a single axis, the incident point IP2 of the coherent light from the irradiation device 60 to the optical element 50 is represented as the hologram recording medium 55. Can be moved in a two-dimensional direction on the plate surface.

  Specific examples of the mirror device 66a included in the scanning device 65 include a MEMS mirror and a polygon mirror.

  The scanning device 65 may be configured to include a reflection device that changes the traveling direction of coherent light by reflection, for example, a device other than the mirror device 66 described above. For example, the scanning device 65 may include a refractive prism, a lens, and the like.

  In the first place, the scanning device 65 is not essential, and the light source 61a of the irradiation device 60 is configured to be able to move, swing, rotate, and the like with respect to the optical element 50. The irradiated coherent light may be scanned on the light deflecting unit 70, and thereby the coherent light deflected by the light deflecting unit 70 may be scanned on the hologram recording medium 55.

  Furthermore, although the light source 61a of the irradiation device 60 has been described on the assumption that the laser light shaped as a linear light beam is oscillated, the present invention is not limited to this. In particular, in the above-described form, the coherent light irradiated to each position of the optical element 50 is shaped by the optical element 50 into a light beam that enters the entire illuminated area LZ. Therefore, there is no inconvenience even if the coherent light irradiated from the light source 61a of the irradiation device 60 to the light deflection unit 70 is not accurately shaped. For this reason, the coherent light generated from the light source 61a may be diverging light. Further, the cross-sectional shape of the coherent light generated from the light source 61a may be an ellipse or the like instead of a circle. Furthermore, the transverse mode of the coherent light generated from the light source 61a may be a multimode.

  When the light source 61a generates a divergent light beam, the coherent light is incident not on a point but in a region having a certain area when entering the hologram recording medium 55 of the optical element 50. In this case, the light diffracted by the hologram recording medium 55 and incident on each position of the illuminated area LZ is multiplexed in angle. In other words, at each moment, coherent light is incident on each position of the illuminated area LZ from a certain angle range. Speckle can be made more inconspicuous by such multiplexing of angles.

  In the above-described embodiment, an example in which the irradiation device 60 includes only a single laser light source 61a has been described. For example, the irradiation device 60 may include a plurality of light sources that oscillate light in the same wavelength region. In this case, the illumination device 40 can illuminate the illuminated area LZ more brightly. Further, coherent lights from different solid laser light sources do not have coherence with each other. Therefore, the multiplexing of the scattering pattern further proceeds and the speckle can be made less noticeable.

  Further, the irradiation device 60 may include a plurality of light sources that generate coherent light in different wavelength ranges. According to this example, a color that is difficult to display with a single laser beam can be generated by additive color mixing, and the illuminated area LZ can be illuminated with that color. Further, in this case, in the projection device 20 or the transmissive image display device 10, the spatial light modulator 30 includes, for example, a color filter, and a modulated image can be formed for each coherent light in each wavelength region. Makes it possible to display images in a plurality of colors. Alternatively, even if the spatial light modulator 30 does not include a color filter, the irradiation device 60 irradiates the coherent light of each wavelength region in a time-sharing manner, and the spatial light modulator 30 is irradiated with the wavelength region. Even when operating in a time-sharing manner so as to form a modulated image corresponding to the coherent light, it is possible to display an image in a plurality of colors. In particular, in the projection device 20 or the transmissive image display device 10, the irradiation device 60 includes a light source that generates coherent light in a wavelength region corresponding to red light, and a light source that generates coherent light in a wavelength region corresponding to green light. In the case where it includes a light source that generates coherent light in a wavelength range corresponding to blue light, it is possible to display an image in full color.

(Optical element)
In the above-described embodiment, the example in which the optical element 50 includes the transmissive relief hologram 55 has been described, but the present invention is not limited thereto. As already described, the optical element 50 may include a plurality of hologram recording media 55. The optical element 50 may include a transmission type volume hologram recording medium using a photopolymer. Furthermore, the optical element 50 may include a volume hologram that is recorded using a photosensitive medium including a silver salt material.

  In addition, in the exposure process shown in FIG. 3, a so-called Fresnel type hologram recording medium is produced. However, a Fourier transform type hologram recording medium obtained by performing recording using a lens may be produced. Absent. However, when a Fourier transform type hologram recording medium is used, a lens may also be used during image reproduction.

  Further, the striped pattern such as the refractive index modulation pattern and the concavo-convex pattern to be formed on the hologram recording medium 55 does not use the actual object light Lo and the reference light Lr, but the planned wavelength and incident direction of the reproduction illumination light La. In addition, it may be designed using a computer based on the shape and position of the image to be reproduced. The hologram recording medium 55 obtained in this way is also called a computer-generated hologram. Even in an example in which such a computer-generated hologram is created as a relief hologram, the angle change of the coherent light in the computer-generated hologram can be minimized by the light deflecting unit 70 as in the basic mode described above. Therefore, it is possible to improve the light utilization efficiency in the computer-generated hologram and to easily design the computer-generated hologram. When a plurality of coherent lights having different wavelength ranges are irradiated from the irradiation device 60 as in the above-described modification, the hologram recording medium 55 as a computer-generated hologram corresponds to each coherent light in each wavelength range. The coherent light in each wavelength region may be diffracted in the corresponding region to reproduce an image.

  Further, in the above-described embodiment, the optical element 50 includes the hologram recording medium 55 that expands the coherent light irradiated to each position and illuminates the entire illuminated area LZ using the expanded coherent light. However, the present invention is not limited to this. The optical element 50 changes or diffuses the traveling direction of the coherent light irradiated to each position instead of the hologram recording medium 55 or in addition to the hologram recording medium 55, and diffuses the entire illuminated area LZ with coherent light. You may make it have a lens array or a diffuser as an optical element to illuminate. Specific examples of such a lens array include a total reflection type or a refractive type Fresnel lens or a fly-eye lens provided with a diffusion function. Specific examples of such a diffusion plate include opal glass, frosted glass, or resin diffusion plate provided with a diffusion function. Note that “diffusion” in the optical element 50 in the present invention means that incident light is angularly expanded in a predetermined direction and emitted, and the diffusion angle by the diffractive optical element, the lens array, or the like is sufficiently controlled. In addition, the case where the emission angle is expanded by scattering particles such as opal glass is also included. Also in such an illuminating device 40, the irradiation device 60 irradiates the light deflection unit 70 with coherent light so as to scan the light deflection unit 70, and thereby the coherent light deflected by the light deflection unit 70 is generated. The lens array of the optical element 50 is scanned, and the coherent light incident on each position of the optical element 50 is changed in the traveling direction by the lens array or the diffusion plate to illuminate at least the illuminated region LZ. By configuring the irradiation device 60, the light deflection unit 70, and the optical element 50, speckle can be effectively made inconspicuous. In the case of a lens array or a diffusing plate, it is not necessary to consider zero-order light. Therefore, the light deflecting unit 70 may deflect the incident coherent light toward the illuminated region LZ.

(Lighting method)
In the above-described embodiment, the irradiation device 60 is configured to be able to scan the coherent light in the one-dimensional direction on the optical element 50 via the light deflecting unit 70, and the hologram recording medium 55 and the lens array of the optical element 50 are configured. Alternatively, the diffusion plate is configured to diffuse the coherent light irradiated to each position in a two-dimensional direction, and thus the illumination device 40 illuminates the two-dimensional illuminated region LZ. However, as described above, the present invention is not limited to such an example. For example, the irradiation device 60 can scan the coherent light in the two-dimensional direction on the optical element 50 via the light deflection unit 70. In addition, the hologram recording medium 55, the lens array, or the diffusion plate of the optical element 50 is configured to diffuse the coherent light irradiated to each position in a two-dimensional direction. The dimensional illuminated area LZ may be illuminated (aspect already described with reference to FIG. 9).

  Further, as already mentioned, the irradiation device 60 and the light deflection unit 70 are configured to be able to scan the coherent light on the optical element 50 in a one-dimensional direction, and the hologram recording medium 55 of the optical element 50 is used. The lens array or the diffusing plate may be configured to diffuse the coherent light irradiated to each position in a one-dimensional direction, so that the illumination device 40 illuminates the one-dimensional illuminated area LZ. . In this aspect, the scanning direction of the coherent light by the irradiation device 60 and the diffusing direction of the hologram recording medium 55 of the optical element, the lens array, or the diffusing plate may be parallel.

  Furthermore, the irradiation device 60 and the light deflecting unit 70 are configured to be able to scan the coherent light in the one-dimensional direction or the two-dimensional direction on the optical element 50, and the hologram recording medium 55, the lens array, The diffusion plate may be configured to diffuse the coherent light irradiated to each position in a one-dimensional direction. In this aspect, as already described, the optical element 50 has a plurality of hologram recording media 55, lens arrays or diffusion plates, and the illuminated areas LZ corresponding to the hologram recording media 55, lens arrays or diffusion plates are sequentially arranged. The illumination device 40 may illuminate a two-dimensional area by illuminating. At this time, each illuminated area LZ may be sequentially illuminated at a speed as if it were illuminated simultaneously by the human eye, or it can be recognized that the illuminated area LZ is also illuminated sequentially by the human eye. It may be illuminated sequentially at such a slow speed.

(Combination of modified examples)
In addition, although the some modification with respect to the basic form mentioned above has been demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

5 Image 6 Scattering plate 10 Projection type image display device 15 Screen 20 Projection device 25 Projection optical system 30 Spatial light modulator 40 Illumination device 50 Optical element 55 Hologram recording medium 58 Hologram photosensitive material 60 Irradiation device 61a Light source 65 Scanning device 66 Mirror device (Reflection device)
66a Reflecting surface 67 Condensing lens 70 Light deflection part LZ Illuminated area

Claims (14)

An optical element capable of diffusing coherent light;
A light deflector provided on the incident side of the optical element, for deflecting and collecting the incident coherent light;
An irradiation device that irradiates the light deflection unit with the coherent light so that coherent light scans the light deflection unit;
The coherent light deflected by the light deflecting unit is guided to the optical element and scanned on the optical element,
The coherent light that has been incident and diffused at each position of the optical element illuminates the entire illuminated area so as to overlap each other.   The illumination device according to claim 1, wherein the optical element is a hologram recording medium.   The illumination device according to claim 2, wherein the hologram recording medium is a transmissive hologram recording medium.   The irradiation device, the light deflection unit, and the hologram recording medium are arranged so that the optical path of the 0th-order light of the coherent light incident on each position of the hologram recording medium deviates from the illuminated area. The lighting device according to claim 2 or claim 3.   The illumination device according to claim 1, wherein the optical element is a lens array that changes a traveling direction of incident light.   The illumination device according to claim 1, wherein the optical element is a diffusion plate that changes a traveling direction of incident light.   The irradiation apparatus includes a light source that generates the coherent light, and a scanning device that changes a traveling direction of the coherent light from the light source so that the coherent light scans on the optical deflection unit. The illumination device according to any one of claims 1 to 6.   The illumination device according to claim 1, wherein the light deflection unit is a lens, a prism, a hologram lens, or a diffractive optical element that deflects the traveling direction of the coherent light by refraction or diffraction.   The illuminating device according to claim 1, wherein the light deflection unit is integrally provided on a surface on an incident side of the optical element. The illumination device according to any one of claims 1 to 9,
Wherein is disposed at a position overlapping the area to be illuminated, obtain Preparations and a spatial light modulator that is illuminated by the illumination device projecting device.   The projection apparatus according to claim 10, further comprising a projection optical system that projects a modulated image obtained on the spatial light modulator onto a screen. A projection device according to claim 10 or 11,
And a screen on which a modulated image obtained on the spatial light modulator is projected. The illumination device according to any one of claims 1 to 9,
Wherein is disposed at a position overlapping the area to be illuminated, obtain Preparations and a screen to be illuminated by the illumination device projection type image display device. An optical element capable of diffusing coherent light;
A light deflector provided on the incident side of the optical element, for deflecting and collecting the incident coherent light;
A scanning device that scans coherent light on the light deflection unit, and
The coherent light deflected by the light deflecting unit is guided to the optical element and scanned on the optical element,
Coherent light that is incident and diffused at each position of the optical element illuminates with the entire illuminated region overlapped with each other.

Images