JP2009042373A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector and a projection device, for surely reducing speckle with simpler constitution. <P>SOLUTION: The projector is equipped with light sources 10R, 10G and 10B emitting light, optical modulation devices 20R, 20B and 20B modulating the light emitted from the light sources 10R, 10G and 10B in accordance with an image signal, and a projection device 40 projecting the image formed by the optical modulation devices 20R, 20G and 20B to a surface to be projected 50. The projection device 40 includes a first optical system for enlarging the image formed by the optical modulation devices 20R, 20G and 20B and forming an intermediate image, a light diffusion member arranged at a position where the intermediate image is formed and diffusing the light emitted from the first optical system, and a second optical system for enlarging and projecting the light diffused by the light diffusion member to the surface to be projected 50. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projector.

2. Description of the Related Art In recent years, projectors that illuminate a light modulation device with an illumination device and enlarge and project image light emitted from the light modulation device onto a screen using a projection optical system such as a projection lens are widely known.
Conventionally, metal halide lamps, halogen lamps, and the like have been used as projector illumination devices. Recently, however, the use of semiconductor lasers (LDs) has been proposed in order to reduce the size of illumination devices and projectors. Advantages of the laser light source include not only miniaturization but also good color reproducibility, video display with high brightness and contrast, and instant lighting.

  However, since the laser light is coherent light, a speckle pattern in which bright spots and dark spots are randomly distributed is generated in the enlarged projected image light. The speckle pattern is generated when light emitted from each point of the projection optical system interferes with an irregular phase relationship. An image having this speckle pattern is a problem because it gives a glare and glimmer to the observer.

  In order to solve this problem, Patent Document 1 discloses that the speckle pattern is changed in a time shorter than the display rewriting time that can be perceived by humans by vibrating and rotating the diffusing element by an external force, and averaging is performed by integration effect. A display device is disclosed in which the eyes of the observer do not keep speckles visually (see, for example, Patent Document 1 and Patent Document 2).

A projection-type image display device described in Patent Document 1 scans a one-dimensional display element in which a plurality of light emitting units or light modulation units are arranged in one direction, and light emitted from the one-dimensional display element, and displays a two-dimensional intermediate image. An optical scanning unit to be formed and a projection lens for enlarging and projecting the two-dimensional intermediate image onto the display unit are provided. Further, a diffuser is disposed and driven between the light scanning means and the projection lens, and temporal phase modulation is applied to the light passing through the diffuser. In this manner, speckle noise is reduced and a good image is obtained.
Further, the display optical system described in Patent Document 2 includes a light source that emits light, a scanning unit that scans light emitted from the light source, a first optical system that displays light scanned by the scanning unit on a display surface, and And a second optical system. The first optical system is an optical system that forms an intermediate image on the light scanned by the scanning unit, and the second optical system is an optical system that forms light from the intermediate image on the display surface. In addition, a light diffusion angle conversion element that increases the divergence angle of the incident laser beam and makes it incident on the second optical system is provided between the first optical system and the second optical system. By this light diffusion angle conversion element, by increasing the incident angle (expansion angle) of the light beam on the scanning surface observed by the observer, a plurality of light components having different incident angles of light incident on the second optical system can be obtained. Can be generated. Thereby, speckle noise can be reduced.
JP 2005-84117 A JP 2006-53495 A

  However, in the techniques described in Patent Document 1 and Patent Document 2, an optical element that diffuses incident light is used. However, simply using such an optical element effectively reduces speckle noise. It is difficult to reduce.

  SUMMARY An advantage of some aspects of the invention is that it provides a projector and a projection apparatus that can reliably reduce speckles with a simpler configuration.

In order to achieve the above object, the present invention provides the following means.
The projector of the present invention includes a light source that emits light, a light modulation device that modulates light emitted from the light source according to an image signal, and a projection that projects an image formed by the light modulation device onto a projection surface. A first optical system for enlarging an image formed by the light modulation device to form an intermediate image, and a position from which the intermediate image is formed. A light diffusing member for diffusing the emitted light and a second optical system for enlarging and projecting the light diffused by the light diffusing member onto the projection surface are characterized.

In the projector according to the present invention, the light emitted from the light source enters the light modulation device, and forms an image of a desired size in the light modulation device. Then, the image formed in the light modulation device by the first optical system is enlarged to form an intermediate image, and then diffused by the light diffusion member, and the image is projected onto the projection surface by the second optical system.
At this time, a light scattering pattern diffused by the light diffusing material is projected onto the projection surface. In the present invention, since the intermediate image magnified by the first optical system is diffused by the light diffusing member, the pitch of the scattering pattern on the projection surface is the same as that of the optical system of the first optical system. Compared to the reciprocal of the magnification of the first optical system, it becomes smaller. That is, it is possible to form a fine scattering pattern pitch on the projection surface with a simple configuration. Therefore, the light emitted from the second optical system is light in which speckle noise is reliably suppressed.
Conversely, in order to form the pitch of the scattering pattern on the projection surface for reducing speckle noise by the light diffusing member, the light diffusion when using a lens unit of the same magnification as the first optical system is used. It becomes larger by the magnification of the first optical system than the pitch of the scattering center of the member. That is, since the size of the scattering center pitch of the light diffusing member can be increased, the manufacture of the light diffusing member is facilitated.

  In the projector according to the aspect of the invention, the light diffusion member may include a plurality of light scattering materials dispersed in a base material, and a projection magnification for projecting an image formed by the light modulation device onto the projection surface may be A. The magnification for forming an intermediate image on the light diffusion member by the first optical system is B, the magnification for projecting the intermediate image on the projection surface by the second optical system is C, and the light diffusion When the pitch between the light scattering materials adjacent to each other is D, it is preferable that D ≦ [(B / A) × 50] = (1 / C) × 50 μm.

  In the projector according to the present invention, it is possible to reliably suppress speckle noise on the projection surface by setting the pitch of the light scattering material so as to satisfy the above-described formula and forming the light diffusion member. . Details will be described later.

  In the projector according to the aspect of the invention, it is preferable that the light diffusion member is a hologram element.

In the projector according to the present invention, the light diffusing member may be a hologram element, for example, a computer generated hologram (CGH: Computer Generated Hologram, hereinafter referred to as CGH) in which a concavo-convex structure artificially created by computer calculation is formed on a glass substrate. Can be used. This CGH is a wavefront conversion element that converts the wavefront of incident light using a diffraction phenomenon. In particular, the phase modulation type CGH can perform wavefront conversion with almost no loss of incident light wave energy. In this way, CGH can generate a uniform intensity distribution or a simple intensity distribution, and thus can be suitably used for a light source device. Furthermore, CGH is preferable because it allows a free setting of the divided region of the diffraction grating and does not cause aberration problems.
Further, the first optical system enlarges an image formed by the light modulation device and forms an intermediate image, so that a hologram element having a size matching the magnification of the first optical system is formed. Thus, by increasing the size of the hologram element, the number of irregularities formed on the glass substrate can be increased. Thereby, since the scattering pattern of the light emitted from the hologram element changes in a more complicated manner, speckle noise can be further reduced.

Furthermore, since the generally used volume type light diffusion plate is thicker in the optical axis direction than CGH, the image that is diffused by the light diffusion plate and projected onto the projection surface by the second optical system is blurred. Resulting in. However, since the CGH is thinner than the light diffusing plate, image blur does not occur, so that a clear image can be displayed.
Furthermore, it becomes possible to produce a CGH in which the degree of light diffusion is controlled so that the second optical system can capture it. As a result, the light diffused by the CGH does not deviate from the second optical system, so that it is possible to suppress light loss.

  In the projector according to the aspect of the invention, the second optical system may include a lens, and the light diffusing member may have a diffusion angle of light diffused by the light diffusing member equal to or larger than a capturing angle of the lens. It is preferable to be formed as follows.

  In the projector according to the present invention, the light diffusing member is formed so that the diffusion angle of the light diffused by the light diffusing member is the same as or smaller than the capturing angle of the lens. Thereby, the intermediate image diffused in the light diffusing member surely enters the second optical system. Accordingly, since all the light expanded by the first optical system is projected onto the projection surface by the second optical system, it is possible to suppress the loss of light amount.

  In the projector according to the aspect of the invention, it is preferable that the magnification of the intermediate image by the second optical system is larger than the magnification of the intermediate image by the first optical system.

  In the projector according to the present invention, since the magnification of the second optical system is larger than the magnification of the first optical system, the size of the light diffusion member can be suppressed to a certain size. Therefore, it is possible to reduce the size of the entire apparatus.

  Embodiments of a projector according to the present invention will be described below with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

[First Embodiment]
A first embodiment of a projector according to the present invention will be described with reference to FIGS.
In the present embodiment, a projector that projects color light including image information generated by a spatial light modulator as a projector on a screen (projected surface) through a projection system will be described as an example.

As shown in FIG. 1, the projector 1 according to the present embodiment uses a reflective screen 50 and projects light including image information onto the screen 50 from the front side of the screen 50.
As shown in FIG. 1, the projector 1 includes a light source device 10, a light modulation device (image forming unit) 20, a dichroic prism (color combining unit) 30, and a projection device 40. In the following description, the light modulation device is referred to as a liquid crystal light valve.
The light source device 10 includes a red light source device (light source) 10R that emits red light, a green light source device (light source) 10G that emits green light, and a blue light source device (light source) 10B that emits blue light.
In addition, the liquid crystal light valve 20 converts the light emitted from the red light source device 10R into two-dimensional red light modulation device 20R that modulates light according to the image information, and the light emitted from the green light source device 10G as image information. A two-dimensional green light modulation device 20G that performs light modulation in response to this and a two-dimensional blue light modulation device 20B that performs light modulation according to image information on the light emitted from the blue light source device 10B. Further, the dichroic prism 30 synthesizes each color light modulated by each light modulator 20R, 20G, 20B.
The projection device 40 projects the light synthesized by the dichroic prism 30 onto the screen 50.

  Each of the light source devices 10R, 10G, and 10B includes a light source 11 that emits light, a diffractive optical element 12 that diffracts light emitted from the light source 11, and an angle adjustment that adjusts an emission angle of light diffracted by the diffractive optical element 12. Optical element 14. In addition, the structure of light source device 10R, 10G, 10B is not restricted to this.

The projection device 40 will be described with reference to FIG. FIG. 2 shows the liquid crystal light valves 20R, 20G, and 20B, the projection device 40, and the screen 50 as a linear arrangement in order to make it easier to see the optical path diagram in which the light incident on the liquid crystal light valve is projected onto the screen 50. The dichroic prism 30 is omitted.
As shown in FIG. 2, the projection device 40 includes a first lens group 41, a diffuser 43, and a second lens group 45 in this order on the optical path.

The first lens group (first optical system) 41 forms the light combined in the dichroic prism 30 as an intermediate image on or near the diffuser 43. The first lens group 41 of the present embodiment is a magnifying optical system that forms an intermediate image B (B> 1) times larger than the image formed by the liquid crystal light valves 20R, 20G, and 20B.
The first lens group 41 is an imaging lens that includes a front lens group 41 a and a rear lens group 41 b that are arranged substantially symmetrically with respect to the aperture stop 42.
Further, it is desirable that the front lens group 41a and the rear lens group 41b have both-side telecentric characteristics in consideration of the viewing angle characteristics of the liquid crystal light valves 20R, 20G, and 20B. The front lens group 41a and the rear lens group 41b are configured to include a plurality of convex lenses and concave lenses, but the lens shape, size, arrangement interval and number, telecentricity, magnification and other lens characteristics are required. It is appropriately changed depending on the characteristics.

As shown in FIG. 2, the second lens group (second optical system) 45 enlarges and projects an intermediate image formed on or near the diffuser 43 onto the screen 50. Here, when the projection device 40 projects the image formed by the liquid crystal light valves 20R, 20G, and 20B to the screen 50 with A magnification, the second lens group 45 is a lens with A / B = C magnification. Use.
As the second lens group 45, as shown in FIG. 2, a single convex lens is shown, but it is actually composed of a plurality of lenses, and the shape, size, arrangement interval, and number of lenses are as follows. It is appropriately changed depending on required characteristics.

Specifically, the first lens group 41 is a double (B = 2) magnifying lens. In addition, the image formed by the liquid crystal light valves 20R, 20G, and 20B by the first lens group 41 is magnified twice on the diffuser 43. At this time, the size of the image formed by the liquid crystal light valves 20R, 20G, and 20B and the intermediate image are similar.
In the present embodiment, for example, when an image formed by the liquid crystal light valves 20R, 20G, and 20B is projected on the screen 50 at 100 times (A = 100), the second lens group 45 is 100/2 = 50 times (C = 50) lens may be used.

  The diffuser (light diffusing member) 43 diffuses the light emitted from the first lens group 41 to generate diffused light, which is emitted from the emission end face 43b. In the present embodiment, the diffuser 43 diffuses the light by diffusing the laser light at the emission end face 43b.

  Next, FIG. 3 shows an enlarged side view of a part of the diffuser 43. In the diffuser 43, light diffusion particles (light scattering material) 43d are irregularly dispersed in a base material 43c that can transmit light, such as quartz (glass), transparent synthetic resin, or the like. The scattering center distance of the light diffusion particle 43d (the pitch of the light diffusion particle 43d) is D. The scattering center distance D is a distance that can reduce speckles generated in an image projected by the second lens group 45.

In the present embodiment, a double lens is used as the first lens group 41, and a 50 × lens is used as the second lens group 45. As a result, in the first lens group 41, the image formed by the liquid crystal light valves 20R, 20G, and 20B is doubled to form an intermediate image, and then diffused by the diffuser 43. Then, the intermediate lens is magnified 50 times by the second lens group 45 and projected onto the screen 50. At this time, the pitch of the scattering pattern caused by the diffuser 43 projected onto the screen 50 is 50D.
Here, the first lens group is compared with a projection apparatus using a 1 × lens. That is, when the first lens group is an equal magnification lens, an intermediate image having the same size as the image formed by the liquid crystal light valves 20R, 20G, and 20B is formed on the diffuser 43. Since the intermediate image is projected by being magnified 100 times by the second lens group, the pitch of the scattering pattern on the screen 50 caused by the diffuser 43 is 100D.

  In the projector 1 according to the present embodiment, an intermediate image formed by enlarging an image formed by the liquid crystal light valves 20R, 20G, and 20B is diffused by the diffuser 43 by the first lens group 41. As a result, the pitch of the scattering pattern on the screen 50 is ½ (1 / B) as compared with the case where the first lens group is an equal magnification lens. That is, it is possible to form a fine scattering pattern pitch on the screen 50 with a simple configuration without rotating (swinging) the diffuser 43. Therefore, the light emitted from the second lens group 45 is light in which speckle noise is suppressed. As a result, the scintillation generated between the screen 50 and the viewer is reduced, the feeling of glare is eliminated, the image by the projected light can be viewed well, and the viewer's fatigue is reduced. Therefore, it is possible to project a high quality image.

In addition, in order to form the scattering pattern pitch 100D1 on the screen 50 for reducing speckles by the diffuser, the pitch of the scattering center of the diffuser when the same-magnification lens group is used as the first lens group is D1. It becomes. The scattering center pitch of the diffuser 43 used in the projector according to the present embodiment is 2D1 (B times D1). That is, as compared with the case where an equal magnification lens is used, the pitch of the scattering center of the diffuser 43 can be increased and speckle noise can be reduced, so that the manufacture of the diffuser 43 is facilitated.
That is, the projector 1 according to the present embodiment can reduce speckles with a simpler configuration.

The first lens group 41 enlarges the image formed by the liquid crystal light valves 20R, 20G, and 20B so as to have a similar shape, and forms an intermediate image, but the area of the intermediate image is the liquid crystal light valves 20R, 20G. , 20B may be used as long as the optical system is larger than the image formed.
The diffuser 43 is preferably formed such that the diffusion angle of light diffused by the diffuser 43 is the same as or smaller than the capture angle of the second lens group 45. In this configuration, the intermediate image diffused in the diffuser 43 is reliably incident on the second lens group 45. Accordingly, since all the light expanded by the first lens group 41 is projected onto the screen 50 by the second lens group 45, it is possible to suppress the loss of the light amount.
In the projector of the present invention, the magnification of the intermediate image (50 times) by the second lens group 45 is larger than the magnification (2 times) of the intermediate image by the first lens group 41. The size can be suppressed to a certain size. Therefore, it is possible to reduce the size of the entire apparatus.

[Modification of First Embodiment]
In the first embodiment shown in FIG. 1, the diffuser 43 in which the light diffusing particles 43 d are dispersed in the base material 43 c is used, but a hologram element may be used as the diffuser (light diffusing member) 51. Such a modification will be described with reference to FIG.

  FIG. 4 shows an enlarged side view of a part of the diffuser 51. The diffuser 51 can be formed of a material that can transmit light, such as quartz (glass) or a transparent synthetic resin. In this embodiment, a surface relief type hologram element is used as the diffuser 51. As the hologram element, for example, a computer generated hologram (CGH: Computer Generated Hologram, hereinafter referred to as CGH) in which a concavo-convex structure artificially created by calculation with a computer is formed on a glass substrate can be used. This CGH is a wavefront conversion element that converts the wavefront of incident light using a diffraction phenomenon. In particular, the phase modulation type CGH can perform wavefront conversion with almost no loss of incident light wave energy. Thus, the CGH can generate a uniform intensity distribution or a simple shape intensity distribution.

Specifically, the diffuser 51 has a plurality of rectangular recesses (uneven structure) 51M having different depths on the surface thereof. In addition, the plurality of convex portions between the concave portions 51M have different heights.
The diffuser 51 can be provided with a predetermined diffusion function by appropriately adjusting the surface conditions of the diffuser 51 including the pitch d between the recesses 51M and the depth (height of the protrusions) t of the recesses 51M. As a design method for optimizing the surface condition, a predetermined calculation method (simulation method) such as an iterative Fourier method is exemplified.
For example, the depth t1 of the diffuser 51 shown in FIG. 4 is about 100 nm, and the thickness in the optical axis O direction is preferably about 1 μm to 10 μm.
Further, since the diffuser 51 is digital data, the boundary of the phase step generated in the concave portion and the convex portion itself functions as a scattering center. For example, when d = 0.5 μm, it has a function similar to that of the scattering material disposed at a pitch of 0.5 μm.

Further, since the first lens group 41 is a lens that enlarges an image formed by the liquid crystal light valves 20R, 20G, and 20B, the diffuser 51 having a size that matches the magnification of the first lens group 41 is formed.
Thus, since the size of the diffuser 51 of the present embodiment is larger than the size of the diffuser when the same-size lens is used as the first lens group 41, the number of recesses 51M formed on the glass substrate. Can be increased. When the light emitted from the first lens group 41 enters the diffuser 51, the scattering pattern of the light emitted from the diffuser 51 changes more complicatedly. As a result, the light emitted from the diffuser 51 and projected onto the screen 50 by the second lens group 45 becomes light in which speckle noise is suppressed.

Here, it compares with the diffuser 43 of 1st Embodiment. The thickness of the diffuser 43 in the optical axis O direction is 1 to 2 mm. Here, the image projected on the screen 50 is an image formed at the rear focal position of the second lens group 45. Therefore, the diffuser plate 44 is thicker than the diffuser 51 used in the present embodiment, and therefore, a lens having a large depth of focus must be used as the second lens group 45. However, by using the diffuser 51, it is only necessary to use a lens having a small depth of focus as the second lens group 45, so that the cost of the lens can be suppressed. Furthermore, since the diffuser 51 of the present embodiment is a hologram element, it is possible to control the degree of light diffusion so that the second lens group 45 can be captured. Thereby, since the light diffused by the diffuser 51 does not come off from the second lens group 45, it is possible to suppress light loss.
The diffuser 51 is not limited to the relief type shown in FIG. 4 but may be a so-called blaze type having a triangular recess having a slope.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described. In the drawings of the respective embodiments described below, portions having the same configuration as those of the projector 1 according to the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
In the projector according to this embodiment, the first lens group 41, the second lens group 45, the scattering center pitch of the diffuser 43, and the diffuser 43 rotate. Different from the embodiment. The overall configuration is the same as that of the first embodiment.

As shown in FIG. 5, the diffuser (light diffusing member) 43 rotates around the central axis P, diffuses the light emitted from the first lens group 41, generates diffused light, and exits from the exit end face 43b. Let In the present embodiment, the diffuser 43 diffuses the light by diffusing the laser light at the emission end face 43b.
According to the experience of the present inventor, a random scattering pattern having a pitch of 50 μm on the screen 50 is changed at about 60 Hz. That is, speckles cannot be perceived by rotating the diffuser 43 at a rotation speed of about 60 Hz.
The rotational speed of the diffuser 43 is not limited to 60 Hz, and may be set to a frequency higher than the flicker frequency that can be detected by humans, for example, 30 Hz or more.

In the present embodiment, for example, a case where an image formed by the liquid crystal light valves 20R, 20G, and 20B on the screen 50 is projected 100 times (A = 100) will be described.
Specifically, the projection device 40 performs enlarged projection with a diagonal length of 100 inches using the liquid crystal light valves 20R, 20G, and 20B with a diagonal length of 1.0 inches.
Here, when a 1 × lens (B = 1) is used as the first lens group 41, a 100 × lens is used as the second lens group 45, so that the scattering pattern pitch on the screen 50 is 50 μm. When the scattering center distance D of the diffuser 43 is D = 50 μm / 100 = 0.5 μm, an ideal scattering pattern can be projected onto the screen 50. However, it is not easy to manufacture the diffuser 43 in which the scattering center distance D of the light diffusing particles 43d is 0.5 μm.
Therefore, the scattering center distance D of the diffuser 43 of the projection device 40 used in the first embodiment is defined as D ≦ [(B / A) × 50] = (1 / C) × 50 μm (Expression 1). That is, in the first embodiment, since A = 100, B = 2, and C = 50, D = 1 μm. Therefore, an ideal scattering pattern for suppressing speckle noise can be projected onto the screen 50 by setting the scattering center distance D of the diffuser 43 of the projection device 40 used in the first embodiment to 1 μm or less.

In the projector according to the present embodiment, even if the scattering center distance D of the light diffusing particles 43d is doubled, the pitch of the scattering pattern on the screen 50 is 50 μm. Therefore, in the present embodiment, the manufacture of the diffuser 43 is facilitated as compared with a case where an equal magnification lens is used as the first lens group. As described above, by forming the diffuser 43 by defining the scattering center distance D of the light diffusion particle 43d so as to satisfy the above-described formula 1, speckles on the screen 50 can be reliably suppressed. .
Note that the rotation axis P is not limited to the center of the diagonal line of the intermediate image of the liquid crystal light valves 20R, 20G, and 20B formed in the diffuser 43, and rotates to an area that is out of the intermediate image formation area K as shown in FIG. The diffuser 60 in which the axis P is disposed may be used. In this configuration, the size of the diffuser 60 is approximately twice that of the diffuser 43. By rotating the region where the intermediate image is not formed on the diffuser 60 as the rotation axis P, the light incident on the diffuser 60 does not generate a dead point (a point where the movement stops for a moment), so that the generation of speckle noise is more effective. Can be suppressed.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, although a cross dichroic prism is used as the color light combining means, the present invention is not limited to this. As the color light synthesizing means, for example, a dichroic mirror having a cross arrangement to synthesize color light, or a dichroic mirror arranged in parallel to synthesize color light can be used.
Further, although a transmissive liquid crystal light valve is used as the light modulator, a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such a light valve include a reflective liquid crystal light valve and a digital micromirror device. The configuration of the projection optical system is appropriately changed depending on the type of light valve used.
Furthermore, the present invention is not limited to projectors, and can be applied to all projection optical systems using laser light such as laser processing machines and exposure apparatuses.
The first optical system has a double-sided telecentric optical system, and has a magnifying lens that magnifies an image formed by the liquid crystal light valve and a collimator lens that collimates the magnified light. It may be.
Further, the configuration of the projector is not limited to the front projector, and may be a rear projector.

1 is an optical path diagram illustrating a schematic configuration of a projector according to a first embodiment of the present invention. It is an optical path figure which shows schematic structure of the projection apparatus of FIG. It is a top view which shows the light-diffusion member used for FIG. It is a top view which shows the modification of the light-diffusion member used for FIG. It is a figure which shows the modification of the light-diffusion member of FIG. It is a figure which shows the modification of the light-diffusion member of FIG.

Explanation of symbols

  D ... scattering center distance, 1 ... projector, 10R ... red light source device (light source), 10G ... green light source device (light source), 10B ... blue light source device (light source), 20R, 20G, 20B ... liquid crystal light valve (light modulation device) , 40 ... Projection device, 41 ... First lens group (first optical system), 43, 51 ... Diffuser (light diffusion member), 45 ... Second lens group (second optical system), 50 ... Screen (projected) surface)

Claims (5)

A light source that emits light;
A light modulation device that modulates light emitted from the light source in accordance with an image signal;
A projection device that projects an image formed by the light modulation device onto a projection surface;
A first optical system in which the projection device enlarges an image formed by the light modulation device to form an intermediate image;
A light diffusing member that is disposed at a position where the intermediate image is formed and diffuses light emitted from the first optical system;
And a second optical system for enlarging and projecting the light diffused by the light diffusing member onto the projection surface. The light diffusing member has a plurality of light scattering materials dispersed in a base material,
The projection magnification for projecting the image formed by the light modulation device onto the projection surface is A times, the magnification for forming an intermediate image on the light diffusion member by the first optical system is B times, and the second optical When the magnification for projecting the intermediate image onto the projection surface by the system is C, and the pitch between the light scattering materials adjacent to the light diffusing member is D,
The projector according to claim 1, wherein D ≦ [(B / A) × 50] = (1 / C) × 50 μm.   The projector according to claim 1, wherein the light diffusion member is a hologram element. The second optical system has a lens;
2. The light diffusing member is formed so that a diffusion angle of light diffused by the light diffusing member is equal to or smaller than a capturing angle of the lens. Item 4. The projector according to any one of Items 3.   The magnification of the intermediate image by the second optical system is larger than the magnification of the intermediate image by the first optical system, according to any one of claims 1 to 4. projector.

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