JP2007334240A - Screen, rear projector, projection system, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screen, a rear projector, a projection system, and an image display device that reliably prevent scintillation by projection light and avoid occurrence of display unevenness and glare to achieve high image quality. <P>SOLUTION: The screen 3 on which imaging light is projected has a function of diffusing incident light to exit it and comprises a diffusing plate 3 rotatable around a rotation axis intersecting the principal plane and a diffusion plate rotating means (motor 35) to rotate the diffusing plate 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a screen, a rear projector, a projection system, and an image display device.

  In recent years, projectors are rapidly spreading. In addition to front-type projectors used mainly for presentation purposes, rear-type projectors have recently been gaining recognition as a form of large-screen display. The greatest advantage of the projection-type image display device is that it can provide a product with the same screen size at a lower price than a direct-view display such as a liquid crystal television and a plasma display. However, recently, the cost of direct view type has also been reduced, and higher image quality performance is required for the projection type image display apparatus. The projector displays an image by irradiating light emitted from a light source to a light modulation element such as a liquid crystal light valve and enlarging and projecting the projection light modulated by the light modulation element on a screen. At this time, not only the image is displayed on the screen but also the viewer sees glare on the entire screen. This is due to luminance unevenness caused by light interference, and is called speckle noise or scintillation.

Here, the principle of scintillation generation will be described.
As shown in FIGS. 12A and 12B, the light emitted from the light source 70 passes through a liquid crystal light valve (not shown) and is projected onto the screen 74. The projection light projected on the screen 74 is diffracted by each scattering material 72 included in the screen 74 and diffused by acting like a secondary wave source. As shown in FIG. 12 (b), the two spherical waves from the secondary wave source cause light intensification and weakening in accordance with the phase relationship between each other, thereby causing bright and dark stripes between the screen 74 and the viewer. A pattern (interference fringe) appears. When the viewer's eyes are focused on the image plane S where the interference fringes are generated, the viewer recognizes the interference fringes as scintillation that makes the screen glaring. Scintillation gives an uncomfortable feeling to a viewer who wants to see an image formed on the screen surface, as if a veil, a lace cloth, a spider web, or the like is stretched between the screen surface and the viewer. In addition, since the viewer sees a double image of the image on the screen and the scintillation and tries to match the viewpoint with each image, it causes great fatigue. Therefore, this scintillation gives an appreciable stress to the viewer.

  By the way, in recent projectors, the development of a new light source that replaces the conventional high-pressure mercury lamp has been developed. In particular, the laser light source is a light source for next-generation projectors in terms of energy efficiency, color reproducibility, long life, and instantaneous lighting. Expectations are rising. However, the projection light on the screen by the laser light source has very high coherence because the phases of the light beams in the adjacent regions are aligned. Since the coherent length of the laser light may be several tens of meters, when the same light source is divided and recombined, the light synthesized through an optical path difference shorter than the coherent length causes strong interference. For this reason, scintillation (interference fringes) that is clearer than the high-pressure mercury lamp appears. Therefore, reduction of scintillation is an indispensable technique especially in the commercialization of projectors using laser light sources.

The following techniques have been proposed as measures for reducing such scintillation.
The technique described in Patent Document 1 optimizes the diffusibility of the screen, and describes a screen having a three-layer structure of a diffusion layer, a transparent layer (lenticular lens), and a diffusion layer. Thus, the randomness of the interference spots increases as the structure of the scattering layer becomes complicated. Therefore, if the fine components in the spots (interference fringes with small spatial frequency) increase, the interference fringes will be integrated and averaged by the afterimage characteristics of the human eye when some line of sight movement occurs, and the interference fringes will disappear. obtain. In particular, in the case of moving image viewing, since the line of sight is frequently moved, reduction of scintillation can be expected.
In Patent Document 2, light, an electric field, a magnetic field, heat, stress, and the like are applied to the light scattering layer, and the shape, relative positional relationship, and refractive index of the light scattering body contained in the light diffusion layer are temporally changed. A screen is disclosed. In this way, it is expected that scintillation is prevented from occurring by temporally changing the scattering distribution and phase of the scattered wave by the light diffusion layer.
Japanese Patent Laid-Open No. 11-038512 JP 2001-100316 A

  However, in Patent Document 1, since the scattering state of the final scattering surface is fixed, the phase distribution of the light beam in the space between the screen and the viewer, where interference between the light beams emitted from each point on the scattering surface is fixed. Has been. Therefore, the interference spot is visually recognized as a fixed image. Therefore, unless frequent line-of-sight movement occurs, the interference spots do not completely disappear, and in particular, a projector having a highly coherent laser light source can hardly obtain the effect. In addition, such countermeasures for increasing scattering cannot cause the original problem of improving the image quality because there is a risk of image blurring.

  In Patent Document 2, a great amount of driving energy is required to change the shape, relative positional relationship, refractive index, and the like of the light scatterer. In addition, when the above driving means is used, the energy transmission efficiency to the scattering layer is low, and vibration, sound, unnecessary electromagnetic waves, exhaust heat, and the like are generated, and there is a possibility that comfortable viewing is hindered. Furthermore, the size of the image changes in a configuration in which the scattering layer moves in the focus direction. As a result, the position of the contour line of the image in the horizontal direction also changes, causing image blurring.

  The present invention has been made in view of the above-described problems, and is capable of reliably preventing scintillation due to projection light and avoiding display unevenness and glare, thereby improving the screen quality and the rear. An object is to provide a projector, a projection system, and an image display device.

  In order to achieve the above object, the screen of the present invention is a screen on which image light is projected, which has a function of diffusing and emitting incident light, and is centered on a rotation axis intersecting with the main surface. And a diffusion plate rotating means for rotating the diffusion plate. Here, the “main surface” is a surface that becomes a light incident surface and a light exit surface of the diffusion plate, and is a surface other than the end surface of the diffusion plate. In addition, the following “diffusion plate” in the present invention is a generic term for all those having the function of diffusing and emitting incident light, such as Fresnel lens plates and lenticular lens plates used for general screens. It is a concept that includes. Of course, a diffuser plate may be provided separately from the Fresnel lens plate and the lenticular lens plate. In that case, the diffuser plate may be a single plate or a plurality of plates. Therefore, the overall configuration of the screen includes a plurality of plates having a function of diffusing and emitting incident light, and at least one of them is configured to rotate as described above. Included in the concept.

  According to the configuration of the present invention, since the diffusion plate is rotated around the rotation axis intersecting the main surface by the diffusion plate rotating means, the scattering state of the projection light irradiated to a certain area on the diffusion plate takes time. It will change in various ways. Along with the change, the visually recognized interference fringe moves or the interference fringe pattern changes in a complicated manner. As a result, the interference fringe pattern is integrated and averaged within the afterimage time of the human eye, and the interference fringe (scintillation) is not visually recognized. Thereby, the interference fringes generated between the screen and the viewer are eliminated, the display unevenness and the glare are eliminated, the image by the projected light can be seen well, and the viewer's fatigue is reduced. Further, the fact that the diffusion plate rotates around the rotation axis intersecting with the main surface is a rotation within the main surface. That is, since the diffusion plate does not move in the focus direction, image blurring does not occur.

  Furthermore, in the present invention, since the rotational movement of the diffusion plate is used, generation of unpleasant noise is relatively suppressed, and a quiet projection system can be configured. Also, the energy required for rotation is only the rotational moment and axial resistance, and it is not necessary to input a large amount of energy. Depending on the diffusivity of the diffusion plate, there is a possibility that the effect can be obtained even if the rotational speed is considerably slow (for example, about 0.1 Hz or less). In this case, the diffusion plate rotating means may be realized by a low power driving mechanism, for example, a driving mechanism that drives a watch hand. In the case of a rotating mechanism, since there are few consumable parts, it will be excellent in durability. Furthermore, since it can be realized with a simple configuration, it is safe and low-cost.

It is desirable that the rotation shaft is disposed outside a region where the image light is projected on the diffusion plate.
In the case of the configuration of the present invention, since the position of the rotation center is fixed, the rotation center is always a stationary point (dead point). However, from the viewpoint of preventing scintillation, it is important that the light scattering state always changes over time. If the light scattering state does not change even for a moment, scintillation occurs and the viewer Feels uncomfortable. At that point, if the center of rotation (rotation axis) that becomes the dead point is arranged outside the projection area, the light scattering state always changes in the projection area in time, and scintillation occurs. Can be reliably eliminated.

The diffusion plate is set such that the light diffusion degree is relatively small on the outer peripheral side relatively far from the rotation axis, and the light diffusion degree is set relatively large on the inner peripheral side relatively close to the rotation axis. It is good also as a structure.
In the case of rotational movement, the linear velocity differs between the outer peripheral side and the inner peripheral side of the diffusion plate, and is large on the outer peripheral side and small on the inner peripheral side. Therefore, parameters such as the number of rotations, the number of diffusion plates, and the degree of diffusion may be optimized so that the scintillation removal effect can be sufficiently obtained even on the inner peripheral side of the diffusion plate. In particular, the diffusion degree can be appropriately adjusted depending on the location in the manufacturing process of the diffusion plate. And the scintillation removal effect becomes more uniform regardless of location.

Another screen of the present invention is a screen on which image light is projected, which has a function of diffusing incident light and emitting it, and is located in the main surface with respect to a rotational center that moves with time. And a diffusion plate rotating means for rotating the diffusion plate. The diffusion plate is rotatable within the main surface.
Also in the screen of this configuration, scintillation can be reliably removed without causing image blur, as in the above-described configuration. Moreover, the thing excellent in silence, energy saving property, durability, etc. is obtained by using rotational motion. Further, in the configuration described above, the position of the rotation center is fixed, whereas in the screen of this configuration, the position of the rotation center in the main surface of the diffusion plate moves with time. Therefore, unlike the above configuration, even if the center of rotation is within the projection area, there is no dead point, and the occurrence of scintillation can be reliably eliminated.

The rear projector of the present invention includes a light source that emits light, a light modulation unit that modulates the light emitted from the light source, the screen of the present invention on which the light modulated by the light modulation element is projected, And projection means for projecting the light modulated by the light modulation element onto the screen.
According to the rear projector of the present invention, since the screen of the present invention is provided, scintillation is surely removed without causing image blur, and the viewer can comfortably view the image. In addition, if the diffusion plate rotating means is accommodated inside the housing, for example, the viewer cannot see the diffusion plate rotating means, and it is difficult to see from the outside that the diffusion plate is rotating. be able to.

A projection system according to the present invention includes the screen according to the present invention, and a projection engine that projects image light onto the screen.
According to the projection system of the present invention, since the screen of the present invention is provided, scintillation is surely removed without causing image blur, and the viewer can view the image comfortably.

A plurality of the projection engines may be provided, and image light from the plurality of projection engines may be projected onto a plurality of different areas on the screen.
A configuration in which image light from a plurality of projection engines is projected onto a plurality of regions, a so-called multi-plane projection type projection system, is particularly suitable for a stationary projection system such as an event venue, a museum, a school, or a wall-embedded projection system. It is. When applied to these, with the above-described configuration, if there is one screen of the present invention, scintillation of a plurality of screens can be removed at a time, and installation efficiency becomes high. Thus, the present invention is particularly effective when a large screen display is installed using a laser projection engine in a large-scale facility.

An image display device of the present invention includes a light source that emits light, the screen of the present invention, and a scanning unit that scans the light emitted from the light source on the screen.
According to the image display device of the present invention, since the screen of the present invention is provided, scintillation is surely removed without causing image blur, and the viewer can comfortably view the image.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view showing a schematic configuration of a rear projector according to the present embodiment. FIG. 2 is a side sectional view of the rear projector. FIG. 3 is a schematic diagram showing the configuration of the projection optical system of the rear projector. FIG. 4 is a perspective view showing a state in which the screen is disassembled. FIG. 5 is a sectional view of the screen. FIG. 6 is a front view showing a modification of the screen rotating means. FIG. 7 is a front view showing another modification of the screen rotating means.
In the following drawings, in order to make the drawings easy to see, the film thicknesses and dimensional ratios of the respective components are appropriately changed. In the following description, an xyz orthogonal coordinate system is set, and the positional relationship of each member will be described with reference to the xyz orthogonal coordinate system. The horizontal direction on the screen (left and right direction viewed by the viewer) is the x direction, the vertical direction on the screen (up and down direction viewed by the viewer) is the y direction, and the depth direction of the screen is the z direction.

  The rear projector according to the present embodiment is a rear projection type projector that modulates light emitted from a light source by a light modulation element and enlarges and projects the modulated light onto a screen. As shown in FIG. 1, the rear projector 1 includes a housing 2 and a screen 3. The screen 3 is attached to the front side of the housing 2, and image light is projected from the rear side of the screen 3, and a viewer positioned on the front side of the screen 3 views the image. A front panel 4 is provided below the screen 3 on the front surface of the housing 2, and openings 5 for outputting sound from speakers (not shown) are provided on the left and right sides of the front panel 4.

Next, the structure inside the housing 2 will be described.
As shown in FIG. 2, a projection engine 7 is disposed below the inside of the housing 2. On the optical path between the projection engine 7 and the screen 3, a reflection mirror 8 and a reflection mirror 9 are installed. With this configuration, the light emitted from the projection engine 7 is reflected by the two reflecting mirrors 8 and 9 and is projected on the projection area T on the upper portion of the screen 3 in an enlarged manner.

Next, a schematic configuration of the projection engine 7 will be described with reference to FIG.
However, in FIG. 3, for the sake of simplification of the drawing, the illustration of the housing 2 constituting the appearance of the rear projector 1 is omitted.
The projection engine 7 includes a light source 11, a light modulation element 12 that modulates light emitted from the light source 11, and a projection lens 13 that projects light modulated by the light modulation element 12. In the present embodiment, liquid crystal light valves 12R, 12G, and 12B are used as the light modulation element 12. That is, the rear projector 1 of the present embodiment is a so-called liquid crystal projector.

  As shown in FIG. 3, the projection engine 7 includes a light source 11, dichroic mirrors 14, 15, reflection mirrors 16, 17, 18, an incident lens 19, a relay lens 20, an exit lens 21, liquid crystal light valves 12R, 12G, 12B, It comprises a cross dichroic prism 22, a projection lens 13, and the like. In addition, an integrator optical system for uniformizing the illuminance distribution of the light emitted from the light source 11, and a polarization conversion optical system for aligning the polarization state of the light emitted from the light source 11 with the polarization used in the liquid crystal light valves 12R, 12G, and 12B. May be provided.

  The light source 11 includes a lamp 24 such as a high-pressure mercury lamp or a metal halide lamp, and a reflector 25 that reflects light from the lamp 24. The dichroic mirror 14 has a function of transmitting red light contained in white light from the light source 11 and reflecting blue light and green light. The dichroic mirror 15 has a function of transmitting blue light and reflecting green light. Therefore, the red light transmitted through the dichroic mirror 15 is reflected by the reflection mirror 16 and enters the red light liquid crystal light valve 12R. The green light reflected by the dichroic mirror 14 is reflected by the dichroic mirror 15 and enters the green light liquid crystal light valve 12G.

  Further, the blue light reflected by the dichroic mirror 14 passes through the dichroic mirror 15. For blue light, in order to prevent light loss due to a long optical path, a light guide means 26 comprising a relay lens system including an incident lens 19, a relay lens 20 and an exit lens 21 is provided. Blue light is incident on the blue light liquid crystal light valve 12B through the light guide means 26.

  The three color lights modulated by the liquid crystal light valves 12R, 12G, and 12B are incident on the cross dichroic prism 22. The cross dichroic prism 22 is formed by bonding four right-angle prisms. A dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an X shape at the interface. Yes. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 3 by the projection lens 13 which is a projection optical system, and the image is enlarged and displayed.

Next, the configuration of the screen 3 will be described with reference to FIGS.
As shown in FIGS. 4 and 5, the screen 3 of the present embodiment is configured by laminating a Fresnel lens plate 28, a lenticular lens array plate 29, a diffusion plate 30, and a protection plate 31 in this order. . These members are stacked on the optical path of the projection light so that the Fresnel lens plate 28 side is located on the inner side of the housing 2 and the protective plate 31 side is located on the outer side (viewer side) of the housing 2. As shown in FIG. 5, on the viewer side of the lenticular lens array plate 29, black masks 32 are provided in a lattice pattern. The presence of the black mask 32 can increase the contrast of the screen 3. A protective plate 31 is fitted into a window 33 (opening) provided on the front surface of the housing 2. Due to the presence of the protection plate 31, it is possible to prevent external dust and dirt from being attached to the diffusion plate 30 and scratching. In FIG. 5, the reflection mirrors 8 and 9 are not shown, and only the projection engine 7 is shown. In FIG. 5, for the purpose of showing the shape of the lenticular lens array plate 29, only the lenticular lens array plate 29 is shown rotated 90 degrees in the xy plane. The longitudinal direction is in the y direction and the radial direction is in the x direction.

  The diffuser plate 30 is made of a plate material or a film material having a circular plan view, and beads (diffusion material) having a refractive index different from that of the transparent member are dispersed in a transparent member in a random distribution. The diffusion plate 30 is a transmission type diffusion plate and has a function (forward scattering property) to diffuse light while transmitting light from one surface to the other surface. The diffusion plate 30 may be a plate-like member such as a glass plate or a film-like member such as resin. Alternatively, as long as the diffusion plate 30 has a function of diffusing light, the diffusion plate is not limited to the one in which the diffusing material is dispersed, but a frosted glass plate having irregularities on the surface, a film on which a diffusion surface is formed, Also good.

  In the case of this embodiment, the screen 3 is provided with a motor 35 (diffusion plate rotating means) for rotating the diffusion plate 30, and a rotation shaft 36 of the motor 35 is attached to the center of the circle of the diffusion plate 30. . The extending direction of the rotating shaft 36 is a direction (z direction) parallel to the normal line of the main surface (light incident surface or light emitting surface) of the diffusion plate 30. With this configuration, with the rotation of the motor 35, the diffusion plate 30 rotates in the plane of the main surface with the center of the circle of the diffusion plate 30 as the rotation center. On the other hand, the Fresnel lens plate 28, the lenticular lens array plate 29, and the protective plate 31 are fixed to an arbitrary support member such as the housing 2.

  Further, the Fresnel lens plate 28, the lenticular lens array plate 29, and the protection plate 31 are arranged above the diffusion plate 30 so as not to interfere with the rotation shaft 36 of the motor 35. A rectangular region in which the Fresnel lens plate 28, the lenticular lens array plate 29, and the diffusion plate 30 overlap each other is a projection region T on which image light from the projection engine 7 is projected. Therefore, the rotation center of the diffusion plate 30 is located outside the projection area T. The motor 35 may be configured to start rotating at the same time as the rear projector 1 is turned on, for example, and needs to continue rotating at least while the image light is projected on the screen 3.

  As the Fresnel lens plate 28 and the lenticular lens array plate 29, well-known ones used in general screens can be used. The lenticular lens array plate 29 is desirably arranged so that the longitudinal direction of each lenticular lens coincides with the y direction (the vertical direction of the screen 3). The protection plate 31 may be an arbitrary plate material or film having a high light transmittance. The Fresnel lens plate 28, the lenticular lens array plate 29, and the protection plate 31 are all formed in a rectangular shape, and are arranged so as to overlap the upper region of the circular diffusion plate 30. In FIG. 4, the dimensions of the Fresnel lens plate 28, the lenticular lens array plate 29, and the protection plate 31 are all shown to be the same, but the dimensions are not necessarily the same.

  According to the configuration of the present embodiment, the diffuser plate 30 whose light scattering state varies depending on the location rotates around the rotation axis 36 perpendicular to the main surface, so that the projection light irradiated to the projection region T on the diffuser plate 30 The scattering state of the liquid changes with time. Along with the change, the interference fringe visually recognized by the viewer moves or the interference fringe pattern changes in a complicated manner. As a result, the interference fringe pattern is integrated and averaged within the afterimage time of the human eye, and the interference fringe (scintillation) is not visually recognized. As a result, the interference fringes generated between the screen 3 and the viewer are eliminated, the display unevenness and the glare are eliminated, and the image by the projected light can be viewed well. Also, viewer fatigue during viewing is reduced. In the case of the present embodiment, since the diffusion plate 30 rotates around the rotation axis orthogonal to the main surface, the diffusion plate 30 does not move in the focus direction (z direction), and image blur does not occur.

  Furthermore, in this embodiment, since the rotational movement of the diffusion plate 30 is used, the generation of unpleasant noise is relatively suppressed as compared with, for example, a reciprocating linear movement, and a quiet rear projector can be configured. Also, the energy required for rotation is only the rotational moment and axial resistance, and it is not necessary to input a large amount of energy. Depending on the degree of diffusion of the diffuser plate 30, the effect can be obtained even if the rotational speed is considerably slow (for example, about 0.1 Hz or less). In that case, the motor 35 may be of low power. Therefore, it is possible to realize a low-cost rear projector that is excellent in durability and safety.

  In the case of the rotation mechanism as in this embodiment, since the position of the rotation center of the diffusion plate 30 is fixed, the rotation center is a stationary point (dead point) at all times, and scintillation occurs when light is projected to this place. Will occur. In this respect, in the case of the present embodiment, since the rotation center (rotation axis) serving as the dead point is located outside the projection area T, the light scattering state is constantly changing in the projection area T. Thus, the occurrence of scintillation can be reliably eliminated.

  In the present embodiment, only the diffusion plate 30 having a random distribution of beads is described. However, the beads are further coarsely dispersed on the outer peripheral side of the diffusion plate 30 and densely dispersed on the inner peripheral side. It may be set such that the diffusivity is small on the outer peripheral side far from the shaft 36 and the diffusivity is increased on the inner peripheral side close to the rotation shaft 36. The linear velocity at an arbitrary point on the diffusion plate 30 is large on the outer peripheral side of the diffusion plate 30 and small on the inner peripheral side. Therefore, if the light diffusivity is relatively small on the outer periphery side and relatively large on the inner periphery side, the difference in the amount of time variation of the diffusivity on the inner and outer periphery can be reduced, and the scintillation removal effect depends on the place It becomes more uniform.

  Further, in the present embodiment, an example of a so-called direct drive type rotational drive mechanism in which the rotation shaft 36 of the motor 35 is directly connected to the center of the diffusion plate 30 is described, but the present invention is not limited to this rotational drive system. An arbitrary rotation transmission mechanism may be provided. For example, in the example shown in FIG. 6, although the diffusion plate 30 has the rotation shaft 36, a motor or the like is not connected to the rotation shaft 36. A roller 38 (diffusion plate rotating means) that rotates by the operation of a motor (not shown) is in contact with the outer periphery of the diffusion plate 30, and the diffusion plate 30 rotates in the reverse direction to the roller 38 as the roller 38 rotates. It is a configuration. Or the example shown in FIG. 7 is a structure which transmits rotation of the motor etc. which are not shown in figure to the diffusion plate 30 via pulley 39a, 39b and the belt 40 (diffusion plate rotation means).

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
The basic configuration of the rear projector of this embodiment is the same as that of the first embodiment, and the configuration of the screen is only different from that of the first embodiment. Therefore, only the configuration of the screen will be described below with reference to FIG.

  As in the first embodiment, the screen 43 according to the present embodiment is configured such that the diffusion plate 44 is rotatable. However, the screen 43 does not have a fixed center of rotation but is located within the main surface of the diffusion plate 44. The feature is that the center of rotation moves with time. That is, as shown in FIG. 8, in the screen 43 of this embodiment, the diffusion plate 44 has an elliptical shape and does not have a substantial rotation axis. The diffusion plate 44 is rotated while being supported by a plurality of (here, four examples) rollers 45 that are in contact with the outer periphery of the diffusion plate 44.

  Each roller 45 is not fixed in position as in the first embodiment shown in FIG. 6, and is configured to be able to move freely while maintaining a state in contact with the outer periphery of the diffusion plate 44. That is, one end of an elastic member 47 such as a spring is connected to the rotation shaft 46 of each roller 45, and the other end of the elastic member 47 is fixed to an arbitrary support member 48 such as a housing of a rear projector. . Further, the elastic member 47 itself is rotatable about the end portion on the side fixed to the support member 48. Therefore, the roller 45 can move freely within a range in which the elastic member 47 can be expanded and contracted. All of the rollers 45 are urged by these elastic members 47 in a direction in which they are pressed against the diffusion plate 44, and the diffusion plates 44 can be supported by these four urging forces even without a fixed rotation axis. .

  Even in the configuration of the present embodiment, interference fringes (scintillation) are removed, display unevenness and glaring sensation are eliminated, and a projected image can be seen well, with excellent quietness, energy saving, durability, safety, and low cost. An effect similar to that of the first embodiment, such as realizing a rear projector, can be obtained.

  On the other hand, the difference from the first embodiment is that the configuration of the present embodiment has no dead point when the diffusion plate 44 rotates. As described above, in the present embodiment, the position of the roller 45 is variable and the diffusion plate 44 is elliptical. Therefore, the diffusion plate 44 is indicated by a position indicated by a solid line or a two-dot chain line in FIG. It is possible to come in position. Accordingly, although the diffusion plate 44 does not have a substantial rotation axis, it has a rotation center (virtual rotation axis), and the rotation center is regarded as moving with time (rotation of the diffusion plate). be able to. Although this rotation center is located in the diffuser plate 44 (in the projection area), since the dead center does not exist because the rotation center moves with time, it is possible to reliably eliminate the occurrence of scintillation. Further, since the rotation of the diffusion plate 44 is in the plane of the diffusion plate 44, there is no movement of the diffusion plate 44 in the focus direction (z direction), and image blurring does not occur.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIGS.
The present embodiment is an example of a projection system that includes a screen and a projection engine separate from the screen. Since the basic configuration of the screen is the same as that of the first embodiment, the same reference numerals are given to the same components in FIG. 9 and FIG. 10 as those in FIG.

  In the first embodiment, only the upper side of the circular diffusion plate is set as one projection area. On the other hand, in this embodiment, in order to effectively use a circular diffusion plate, a plurality of projection regions T1 to T4 are provided on one diffusion plate 30 as shown in FIGS. In each of the projection areas T1 to T4, as described in the first embodiment, a Fresnel lens plate and a lenticular lens array plate are arranged (not shown). These Fresnel lens plates and lenticular lens array plates may be individually arranged in a rectangular shape corresponding to only each projection area, or may be arranged integrally over a plurality of projection areas.

  The projection system shown in FIG. 9 is an example in which two projection areas T1 and T2 are provided on the upper and lower sides of the diffuser plate 30, and two projection engines 7a and 7b are arranged so as to correspond thereto. Image light from the two projection engines 7a and 7b is projected onto two different projection areas T1 and T2, respectively. The projection system shown in FIG. 10 is an example in which four projection areas T1 to T4 are provided on the upper, lower, left, and right sides of the diffusion plate 30 and four projection engines (not shown) are arranged so as to correspond thereto. Moreover, as shown in FIG. 10, you may arrange | position the mask decorative board 49 which formed the window 49a (opening) in the position corresponding to projection area | region T1-T4 in the front side (viewer side) of a screen.

  As in the present embodiment, a configuration in which image light from a plurality of projection engines is projected onto a plurality of projection areas, a so-called multi-projection projection system, is particularly a stationary projection system for event venues, museums, schools, etc. Or it is suitable for a wall-embedded projection system. When applied to these, with the above-described configuration, if there is one screen of the present invention, scintillation of a plurality of screens can be removed at a time, and installation efficiency becomes high. Thus, the present invention is particularly effective when a large screen display is installed using a laser projection engine in a large-scale facility. In this case, as shown in FIG. 10, separate images can be projected on a plurality of screens. Alternatively, it is possible to realize a large screen by arranging a plurality of projection areas adjacent to each other and projecting a series of panoramic images, for example, a so-called tiling method.

[Fourth Embodiment]
Next, a fourth embodiment will be described with reference to FIG.
This embodiment is an image display device using a scanning unit without using a light modulation element such as a liquid crystal light valve. In addition, since the structure of a screen is the same as that of the said 1st Embodiment, the same code | symbol is attached | subjected to a common component and detailed description is abbreviate | omitted.

FIG. 11 is a cross-sectional view showing a schematic configuration of the rear projector 120 (image display device).
As shown in FIG. 11, the rear projector 120 of the present embodiment includes a light source 102 that emits laser light, a lens optical system 103 that includes a collimating optical system 104 and a beam shaping optical system 105, and incident laser light. A scanner 82 (scanning means) that scans in a two-dimensional direction, a projection lens 114 that magnifies and projects the scanned light, a reflection mirror 109 that reflects the projected light toward the screen 3, and a drive unit 107 are provided. Yes. The light source 102 includes a red laser diode 102R that emits red laser light, a green laser diode 102G that emits green laser light, and a blue laser diode 102B that emits blue laser light.

  Laser light emitted from the laser diodes 102R, 102G, and 102B enters the scanner 82 through the lens optical system 103. The incident laser light is scanned (scanned) in a two-dimensional direction by the scanner 82 and projected onto the screen 3 via the projection lens 114 and the reflection mirror 109. In this way, the rear projector 120 of the present embodiment forms an image by causing the scanner 82 to scan the screen 3 with the laser light emitted from the light source 102.

  The scan-type rear projector 120 using the laser light source as in this embodiment also uses the screen 3 of the above embodiment, so that the same operational effects as the above embodiment can be obtained, and scintillation can be effectively reduced. Can be made.

  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, in the first embodiment, the rotation axis of the diffusion plate is arranged perpendicularly (normal direction) to the main surface of the diffusion plate, but is slightly inclined so as to form an angle other than perpendicular to the main surface of the diffusion plate. It may be arranged. In this case, the diffusing plate does not rotate within the main surface, but rotates while causing surface blurring. Therefore, since the movement in the focusing direction occurs particularly on the outer peripheral side of the diffusion plate, scintillation can be more effectively removed although there is a possibility that some image blur may occur. In this configuration, the projection image may be changed at high speed according to the position of the surface of the diffusion plate. Thereby, for example, a three-dimensional image having depth information can be displayed.

  In the above embodiment, the screen includes a Fresnel lens plate, a lenticular lens array plate, and a diffuser plate, and the diffuser plate rotates. However, as long as at least one of them rotates. good. Alternatively, a configuration may be adopted in which a plurality of diffusion plates are provided and at least one of them is rotated. In either case, the same actions and effects as in the above embodiment can be obtained. In addition, the specific configurations of the diffusion plate, the diffusion plate rotation mechanism, and the like exemplified in the above embodiment are not limited to the above embodiment, and can be changed as appropriate. The present invention can also be applied to a rear projector as a whole that uses a liquid crystal light valve as a light modulation element, or a reflection type light modulation element such as a DMD (Digital Micromirror Device) element. .

1 is a perspective view showing a configuration of a rear projector according to a first embodiment of the present invention. 2 is a side sectional view of the rear projector. FIG. 2 is a schematic configuration diagram of an optical system of a projection engine of the rear projector. FIG. FIG. 2 is a perspective view showing a state where the screen of the rear projector is disassembled. It is sectional drawing of a screen same as the above. It is a front view which shows the modification of the rotation means of a screen equally. It is a front view which shows the other modification of the rotation means of a screen same as the above. It is a front view which shows the screen of 2nd Embodiment of this invention. It is a front view which shows the projection system of 3rd Embodiment of this invention. It is a front view which shows the other example of the same projection system. It is sectional drawing which shows the image display apparatus of 4th Embodiment of this invention. It is a figure for demonstrating the generation | occurrence | production principle of scintillation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,120 ... Rear projector (image display apparatus) 3,43 ... Screen, 7 ... Projection engine, 12, 12R, 12G, 12B ... Liquid crystal light valve (light modulation element), 13 ... Projection lens, 28 ... Fresnel lens plate , 29 ... Lenticular lens array plate, 30, 44 ... Diffusion plate, 35 ... Motor (diffusion plate rotating means), 36 ... Rotating shaft, 38, 45 ... Roller (diffusing plate rotating means), 39a, 39b ... Pulley (diffusing plate) Rotating means), 40 ... belt (diffuser plate rotating means), T ... projection area.

Claims (8)

A screen on which image light is projected,
A diffusion plate having a function of diffusing and emitting incident light, and being rotatable about a rotation axis intersecting with the main surface;
And a diffusion plate rotating means for rotating the diffusion plate.   The screen according to claim 1, wherein the rotation shaft is disposed outside a region where the image light is projected on the diffusion plate.   The diffusion plate is set such that the light diffusion degree is relatively small on the outer peripheral side relatively far from the rotation axis, and the light diffusion degree is set relatively large on the inner peripheral side relatively close to the rotation axis. The screen according to claim 1, wherein the screen is provided. A screen on which image light is projected,
A diffusion plate having a function of diffusing and emitting incident light, and being rotatable in the main surface with respect to a rotation center located in the main surface and moving in time;
And a diffusion plate rotating means for rotating the diffusion plate. A light source that emits light;
A light modulating means for modulating light emitted from the light source;
The screen according to any one of claims 1 to 4, wherein light modulated by the light modulation element is projected;
A rear projector comprising: projection means for projecting light modulated by the light modulation element onto the screen.   A projection system comprising: the screen according to claim 1; and a projection engine that projects image light onto the screen.   The projection system according to claim 6, comprising a plurality of the projection engines, wherein image light from the plurality of projection engines is respectively projected onto a plurality of different areas on the screen. A light source that emits light;
A screen according to any one of claims 1 to 4,
An image display apparatus comprising: a scanning unit that scans the light emitted from the light source on the screen.

Images