JP2008203608A - Projector, screen and projection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of surely preventing scintillation caused by projection light, and achieving high image quality, and to provide a screen and a projection system. <P>SOLUTION: The projector includes: a light source that emits light; a light modulating means for modulating the light emitted from the light source in accordance with an image signal; a cooling medium 23a for receiving heat generated from an optional optical component; a screen having a light diffusion layer 12 for diffusing the incident light; and a projecting means for projecting the light modulated by the light modulating means on the screen. The projector is characterized in that the light diffusion layer 12 includes a storage cavity K where light scattering materials 23b are movably dispersed, and the cooling medium 23a flows in the storage cavity K. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projector, a screen, and a projection system.

  In recent years, projectors are rapidly spreading. In addition to front projection projectors that have been used mainly for business presentation applications, recently, rear projectors have been gaining recognition as a form of large televisions (PTVs). The biggest advantage of the projection system is that it can supply products with the same screen size at a lower price than direct-view displays such as liquid crystal televisions and PDPs. However, the price reduction is also progressing in the direct view type, and higher image quality performance is being demanded for the projector display device.

  The projector irradiates light emitted from a light source such as an arc lamp onto a light modulation element of a liquid crystal light valve, and projects the projection light modulated by the light modulation element onto the screen to display an image on the screen. . At this time, not only an image is displayed on the screen, but the entire screen appears glaring. This is due to luminance unevenness caused by light interference, and is called speckle noise, so-called scintillation.

Here, the principle of scintillation generation will be described.
As shown in FIG. 13, the light emitted from the light source 201 passes through the liquid crystal light valve 202 and is projected onto the screen 204 by the projection lens 203. The projection light projected on the screen 204 is diffracted by the scattering structure of the screen 204, and diffused by acting like a secondary wave source. Two spherical waves from the secondary wave source appear as bright and dark stripes (interference fringes) between the screen 204 and the viewer by causing the light to strengthen or weaken depending on the phase relationship between each other. . When the viewer is focused on the image plane 205 where the interference fringes are generated, the viewer recognizes the interference fringes as scintillation that makes the screen glaring.

  Scintillation gives the viewer an unpleasant feeling as if a veil, a lace cloth, or a spider web is stretched between the screen surface and the viewer by the viewer who wants to see the image formed on the screen surface. In addition, the viewer sees a double image of the image on the screen and the scintillation, and causes great fatigue because it tries to match the viewpoint to each. Therefore, this scintillation imparts stress to the viewer.

Recently, development of new light sources that replace conventional high-pressure mercury lamps has been underway, and in particular, laser light sources are expected to become light sources for next-generation projectors in terms of energy efficiency, color reproducibility, long life, and instantaneous lighting. ing. However, the projection light on the screen by the laser light source has very high coherence since the phases of the light beams in the adjacent regions are aligned. Since the coherence length of a laser light source can be as long as several tens of meters, splitting the same light source and recombining will cause strong interference from the light synthesized through the optical path difference shorter than the coherence length. A clearer scintillation (interference fringe) appears than a mercury lamp.
Therefore, reduction of scintillation is an essential technology especially in the commercialization of projectors using laser light sources.

By the way, what has projected the image | video using the projector as mentioned above and making the flowing water into a screen is proposed (for example, refer patent document 1 and patent document 2).
The fountain-type projection device described in Patent Document 1 includes a liquid reservoir portion having an outlet that allows water to flow down to form a film-like waterfall, a mixed liquid pressure feeding unit that pumps a mixed liquid of water and air, And a nozzle having a small hole. With this configuration, the mixed liquid pressure feeding means causes the water containing bubbles to flow from the outlet of the liquid reservoir in a film shape, and projects an image from the projector (projector) onto the film-shaped water. In this way, a natural waterfall is felt by the film-like flowing water.
Further, in the water wall unit described in Patent Document 2, water is accommodated in a hollow liquid tank unit in which both front and rear wall surfaces are formed of a light transmitting plate. This liquid tank unit can generate a large amount of bubbles inside. And a water supply nozzle is provided in the lower part of the liquid tank unit, water is continuously supplied from this water supply nozzle, and water overflows from the upper part of the liquid tank unit. In this configuration, an ornamental fish is accommodated in the liquid tank unit, and a desired image is projected on the front wall surface portion of the liquid tank unit using a projector, thereby integrating the image and the fish. Give an impression.
Japanese Patent Laid-Open No. 7-181595 Japanese Patent Laid-Open No. 7-84548

  However, the fountain-type projection device described in Patent Document 1 and the water wall unit described in Patent Document 2 are not intended as a countermeasure for scintillation because they are intended to use a fluid as a screen itself. In addition, since bubbles are generated in the water serving as the screen, it is difficult to project a high-quality image.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a projector, a screen, and a projection system that can reliably prevent scintillation due to projection light and achieve high image quality. And

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 unit that modulates the light emitted from the light source according to an image signal, a cooling medium that receives heat generated from an arbitrary optical component, and an incident light A screen having a light diffusing layer for diffusing light; and a projecting means for projecting the light modulated by the light modulating means onto the screen, wherein the light diffusing material is movably dispersed. An accommodation space is provided, and the cooling medium flows in the accommodation space.

In the projector according to the present invention, the light emitted from the light source is modulated in accordance with the image signal by the light modulating unit, and the modulated light is projected onto the screen by the projecting unit. At this time, the cooling medium flows in the accommodation space provided in the light diffusion layer of the screen. As the cooling medium flows, the position of the light scattering material in the entire accommodation space changes every moment. Along with the change, the speckle (spot pattern due to interference) visually recognized moves or the speckle pattern changes in a complicated manner. As a result, the speckle pattern is integrated and averaged within the afterimage time of the human eye, and scintillation due to speckle (light glare phenomenon) is not visually recognized. As a result, the scintillation generated between the screen and the viewer is removed, the feeling of glare is eliminated, the image by the projected light can be viewed well, and the viewer's fatigue is reduced. Further, since scintillation can be removed without moving the light diffusion layer in the focus direction, image blur does not occur. This makes it possible to project a high quality image.
Further, the cooling medium that has received the heat generated from the optical component flows into the accommodating space of the light diffusion layer of the screen. As described above, since the heat radiation area can be increased by the accommodation space, the optical component can be efficiently cooled. In addition, since the cooling medium that receives the heat of the optical component flows through the screen, the existing cooling medium can be efficiently used for preventing scintillation.

In the projector according to the aspect of the invention, it is preferable that the cooling medium is a liquid.
In the projector according to the present invention, since the cooling medium is a liquid, dust or the like is less likely to be mixed as compared with the gas, so that a clear image can be displayed. Further, by using a liquid as the cooling medium, the heat dissipation effect is higher than that of gas, so that the cooling efficiency of any optical component can be improved.

In the projector according to the aspect of the invention, it is preferable that the cooling medium is a gas.
In the projector according to the present invention, bubbles may be mixed in the liquid, but if the cooling medium is a gas, the bubbles can be avoided. Therefore, the image is not deteriorated due to bubbles, and a clear image can be displayed.

  In the projector according to the aspect of the invention, it is preferable that the light diffusion layer is provided with a rectifying unit that rectifies the flow of the cooling medium.

  In the projector according to the present invention, the cooling medium flows into the rectification unit, and the rectification unit spreads the cooling medium inside the accommodation space. As a result, it is possible to avoid that the warmed cooling medium stays locally in the accommodation space and the flow is disturbed and the stagnation point is generated, thereby causing an uneven flow. Therefore, scintillation can be reliably prevented, and deterioration in image quality due to flow can be suppressed.

  In the projector according to the aspect of the invention, it is preferable that a porous member that is made of a porous material, allows the cooling medium to pass therethrough, and does not allow the light scattering material to pass through is provided in the housing space.

In the projector according to the present invention, the housing space is made of a porous material, and a porous member that allows the cooling medium to pass therethrough and the light scattering material cannot pass therethrough is provided. There is no flow outside. Therefore, for example, since the light scattering material does not flow in the inflow pipe and the discharge pipe provided to be circulated in the accommodation space of the light diffusion layer, it is possible to avoid the possibility that the light diffusion material is clogged in the piping outside the accommodation space. Become. That is, the cooling medium can be smoothly circulated in the accommodation space.
In addition, since the light scattering material only needs to be at least on the screen, it is possible to minimize the amount of light scattering material used by providing the light scattering material only in the screen.

  In the projector according to the aspect of the invention, it is preferable that the screen includes an angle conversion member that converts an angle of incident light.

  In the projector according to the present invention, the light incident on the screen is emitted after the angle is converted by the angle conversion member. Thereby, for example, the light incident on the screen can be converted into parallel light and the gain of the screen can be adjusted, or the viewing angle can be adjusted by diffusing to a predetermined angle to widen the viewing angle. Therefore, the light emitted from the screen can be brought into a suitable state.

  The screen of the present invention is a screen used with a projection engine provided with a cooling medium, and has a light diffusion layer for diffusing light emitted from the projection engine, and the light diffusion layer is at least in an image forming region. And a housing space in which the light scattering material which is movable and accommodates the cooling medium is dispersed.

The projection light emitted from the projection engine is projected onto the screen according to the present invention. At this time, the cooling medium flows in the accommodation space provided in the light diffusion layer. As the cooling medium flows, the position of the light scattering material in the entire accommodation space changes every moment. 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. As a result, the interference fringes generated between the screen and the viewer are removed, the feeling of glare is eliminated, the image by the projected light can be viewed well, and the viewer's fatigue is reduced. Further, since the interference fringes can be removed without moving the light diffusion layer in the focus direction, image blur does not occur.
Further, the received cooling medium flows into the accommodation space of the light diffusion layer. As a result, a heat radiation area can be increased by at least the accommodation space provided in the image forming region, and thus heat generated from the projection engine can be efficiently cooled.

  The screen of the present invention is preferably provided with a heat radiating member exposed to the outside at least in the image forming area.

  In the screen according to the present invention, since the heat radiating member exposed to the outside is provided at least in the image forming area, the heated cooling medium can be radiated to the outside by the heat radiating member provided on almost the entire surface of the screen. It becomes. Therefore, the cooling medium can be radiated efficiently.

  The projection system according to the present invention includes a projection engine, the screen on which the projection light emitted from the projection engine is projected, and a communication unit that allows the cooling medium to flow into and communicates the housing space with the projection engine. It is characterized by providing.

  In the projection system according to the present invention, the cooling medium of the projection engine flows through the communicating portion and flows into the accommodating space of the light diffusion layer of the screen. Therefore, similarly to the projector described above, it is possible to realize a projection system that does not give stress to the viewer with high image quality by reliably and efficiently preventing scintillation due to projection light and suppressing glare.

  Hereinafter, embodiments of a projector, a screen, and a projection system according to the present invention will be described 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]
FIG. 1A is a perspective view showing a schematic configuration of a rear projector (projector) 1 according to the present embodiment, and FIG. 1B is a side sectional view of the rear projector 1 shown in FIG. . The rear projector 1 according to the present embodiment modulates light emitted from a light source device by a light modulation unit, and enlarges and projects the modulated light onto a screen 10.

  As shown in FIG. 1A, the rear projector 1 includes a housing (holding unit) 2 and a screen 10 that is attached to the front surface of the housing 2 and onto which an image is projected. A front panel 3 is provided in the casing 2 below the screen 10, and openings 4 for outputting sound from speakers are provided on the left and right sides of the front panel 3.

Next, the internal structure of the housing 2 of the rear projector 1 will be described.
As shown in FIG. 1B, a projection optical system 30 is disposed below the housing 2 of the rear projector 1. Reflecting mirrors 5 and 6 are provided between the projection optical system 30 and the screen 10, so that light emitted from the projection optical system 30 is reflected by the reflection mirrors 5 and 6 and projected onto the screen 10 in an enlarged manner. It has become.

First, details of the screen 10 will be described.
As shown in FIG. 2, the screen 10 includes a Fresnel plate (angle conversion member) 11 that converts the angle of incident light, a lenticular plate (angle conversion member) 13 having optical transparency, a Fresnel plate 11, and a lenticular plate. 13 and a diffusion plate (light diffusion layer) 12 that diffuses incident light.

First, the diffusion plate 12 will be described.
As shown in FIG. 2, the diffusion plate 12 diffuses the laser light emitted from the emission surface 11 b of the Fresnel plate 11 and emits it toward the incidence surface 13 a of the lenticular plate 13. Further, as shown in FIG. 3, the diffusion plate 12 includes a first substrate 21 disposed on the incident side, a second substrate 22 disposed on the emission side, and a dispersion medium 23. The first substrate 21 and the second substrate 22 are both light transmissive and are, for example, glass plates. In addition, as a material of the 1st board | substrate 21 and the 2nd board | substrate 22, in addition to being transparent, such as a polycarbonate and a cycloolefin type resin, it is called low hygroscopicity, heat resistance, low birefringence, and high dimensional stability. It is preferable to be made of a material having such properties.

FIG. 4 is an enlarged view of the upper end side of the diffusion plate 12.
As shown in FIG. 4, the diffusion plate 12 is provided with a space sealed by a sealing material 24 provided along the peripheral edge between the first substrate 21 and the second substrate 22. The space is a storage space K in which the dispersion medium 23 is stored. An area corresponding to the accommodation space K of the first substrate 21 is an image display area (image formation area) A in which an image is displayed by the projection optical system 30.
The dispersion medium 23 includes a cooling medium 23a and diffusible particles (light scattering material) 23b provided inside the cooling medium 23a. The cooling medium 23a is a liquid. The particles 23b can continue to be dispersed without sinking depending on conditions such as the material of the cooling medium 23a and the particles 23b and the size and weight of the particles 23b. The cooling medium 23a is preferably made of a light-transmitting material. For example, a non-electrically conductive organic medium is used, and the cooling medium 23a has a surfactant that promotes charging of the particles 23b. Is added. Further, a substance for facilitating charging is added to the particles 23b.
The dispersion medium 23 is a fluid that flows into the screen 30 from a liquid cooling unit 50 described later.

  The particles 23b are preferably made of a light-transmitting material. Specifically, fine particles (beads) of silica, glass, resin, and the like can be used. preferable. The particle 23b has only to have a size suitable for both the light diffusion effect and the particle dispersion effect. If the particle 23b is too small, the light scattering efficiency as the screen 10 is lowered. If the particle 23b is too large, the light scattering distribution is forward scattered. Since it is biased to the side, good diffusion characteristics cannot be obtained. Thereby, although the average particle diameter of particle | grains 23b is not specifically limited, It is preferable that they are 0.5 micrometer-50 micrometers.

Moreover, as shown in FIGS. 4 and 5, the upper end portion 12 a of the diffusion plate 12 includes a flow path 26 and a rectifying unit 40. In addition, the arrow F shown in FIG. 5 has shown the flow of the dispersion medium 23, and the dispersion medium 23 flows from the upper end part 12a of the diffusion plate 12 to the lower end part 12b.
The flow path 26 is formed in the inflow part 27 provided in the upper end part 12a of the diffusion plate 12, as shown in FIG. In the flow path 26, an inflow port 27 b for allowing the dispersion medium 23 to flow into the accommodation space K is formed on the left end surface 27 a of the inflow portion 27. Furthermore, the flow path 26 extends along the upper side of the diffusion plate 12 as shown in FIG. The inflow portion 27 is provided with an inflow pipe 28 communicating with the inflow port 27b. As shown in FIG. 5, a discharge port 12c is provided at the lower end 12b of the diffusion plate 12, and a discharge pipe 29 communicating with the discharge port 12c is further provided. Thereby, the dispersion medium 23 in the accommodation space K flows in from the inflow port 27b through the inflow pipe 28, and is discharged to the outside through the discharge pipe 29 from the discharge port 12c.

As shown in FIG. 5, the rectifying unit 40 is formed on the sealing material 24 on the upper end 12 a side of the diffusion plate 12. The rectifying unit 40 is formed with a plurality of (eight in the example shown in FIG. 5) through holes 41. The through hole 41 has a tapered shape in which a cross-sectional area increases from the side surface 26 a of the flow channel 26 toward the accommodation space K. With the through hole 41 having such a shape, it is possible to spread the inflowing dispersion medium 23 into the accommodation space K as shown by an arrow F in FIG.
Further, as shown in FIG. 5, the rectifying unit 40 is provided outside the image display area A where an image is displayed by the projection optical system 30.

Next, the Fresnel plate 11 will be described.
As shown in FIG. 3, the Fresnel plate 11 is formed with a prism-shaped Fresnel lens 11c formed in a substantially concentric shape on an exit surface 11b opposite to the entrance surface 11a. The Fresnel lens 11c refracts the radially diffusing laser light emitted from the projection optical system 30 and incident from the incident surface 11a toward the diffuser plate 12 (observer direction), converts it into parallel light, and converts it from the emergent surface 11b. It is to be ejected.
Further, the tip of the Fresnel lens 11c is chamfered. In addition, R attachment may be given to the front-end | tip of the Fresnel lens 11c.

Next, the lenticular plate 13 will be described.
As shown in FIG. 3, the lenticular plate 13 is provided with a plurality of bowl-shaped microlens elements 13c on the incident surface 13a on the laser beam incident side. The plurality of microlens elements 13c have a longitudinal direction in the y direction (vertical direction when the screen is installed) on a plane perpendicular to the optical axis O (xy plane), and are arranged in parallel in the x direction. . Further, the tip of the microlens element 13c is rounded. Note that the tip of the microlens element 13c may be chamfered.
The lenticular plate 13 diffuses the laser beam incident from the incident surface 13a within a predetermined angle range and emits it from the emission surface 13b. Thereby, the viewing angle of the image is widened, and a good image can be observed even when the screen 10 is observed at a position shifted from the front in the horizontal direction. The material of the lenticular plate 13 may be any material that transmits light.

  Examples of the material for the Fresnel plate 11 and the lenticular plate 13 include thermoplastic resins such as acrylic resins, polycarbonate resins, and vinyl chloride resins, and cycloolefin resins.

Next, a schematic configuration of the projection optical system 30 of the rear projector 1 will be described.
FIG. 6 is a schematic diagram showing the configuration of the projection optical system 30 of the rear projector 1. In FIG. 6, the casing 2 constituting the rear projector 1 is omitted for simplification.

  The projection optical system 30 includes a red laser light source (light source) 31R that emits red light, a green laser light source (light source) 31G that emits green light, a blue laser light source (light source) 31B that emits blue light, and these lasers. Liquid crystal light valves (light modulation means, optical components) 34R, 34G, and 34B for modulating laser light emitted from the light sources 31R, 31G, and 31B and laser light modulated by the liquid crystal light valves 34R, 34G, and 34B are combined. A cross dichroic prism (color light synthesizing means) 36 and a projection lens (projection means) 37 for enlarging and projecting the laser beam synthesized by the cross dichroic prism 36. Further, the projection optical system 30 is provided with a liquid cooling unit 50 for cooling the liquid crystal light valves 34R, 34G, and 34B.

  The projection optical system 30 is arranged behind each laser light source 31R, 31G, 31B as a uniform illumination system for uniformizing the illuminance distribution of the laser light emitted from the laser light sources 31R, 31G, 31B. Illumination optical systems 32R, 32G, and 32B that emit light to the liquid crystal light valves 34R, 34G, and 34B are provided. For example, the illumination optical system includes a hologram and a field lens.

  In addition, polarizing plates (not shown) are arranged on the incident side and the emission side of each liquid crystal light valve 34R, 34G, 34B. Of the light beams from the laser light sources 31R, 31G, and 31B, only linearly polarized light in a predetermined direction passes through the incident side polarizing plate and enters the liquid crystal light valves 34R, 34G, and 34B. Further, a polarization conversion means (not shown) may be provided in front of the incident side polarizing plate. In this case, the light use efficiency can be improved by converting the light into the light transmitted through the incident-side polarizing plate by the polarization conversion means.

  The three color lights modulated by the liquid crystal light valves 34R, 34G, and 34B are incident on the cross dichroic prism 36. This prism is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 10 by the projection lens 37, which is a projection optical system, and an enlarged image is displayed.

  As shown in FIG. 7, the liquid cooling unit 50 includes a main tank 51, a fluid pumping unit 52, an element cooling pipe 53, a branch tank 54, a merging tank 55, a radiator 56, an axial fan 57, a pipe Parts 58, 66 and 67. Note that FIG. 7 is described with some members in the liquid cooling unit 50 omitted in order to simplify the description.

  The main tank 51 temporarily accumulates the dispersion medium 23 as shown in FIG. In addition, on the peripheral surface of the main tank 51, an inflow portion 51A and an outflow portion 51B for the dispersion medium 23 are formed. Then, the dispersion medium 23 that has flowed out of the main tank 51 is sent to the fluid pressure feeding unit 52 via the pipe unit 58.

As shown in FIG. 7, the fluid pumping unit 52 sucks the dispersion medium 23 from the main tank 51 inside, and forcibly discharges the dispersion medium 23 toward the branch tank 54 to the outside. That is, the outflow part 51B of the main tank 51 and the inflow part 52A of the fluid pumping part 52 are connected via the pipe part 58, and the outflow part 52B of the fluid pumping part 52 and the inflow part 54A of the branch tank 54 are connected to the pipe part 58. Connected through.
The fluid pumping unit 52 is a fluidizing part that causes the dispersion medium to flow in the accommodation space K.

As shown in FIG. 7, the branch tank 54 branches the dispersion medium 23 sent from the fluid pumping unit 52 toward the element cooling pipes 53.
As shown in FIGS. 8A and 8B, the element cooling pipe 53 is disposed on the periphery of the liquid crystal light valve 34R with respect to red light. The dispersion medium 23 flows in from the inflow portion (IN) of the element cooling pipe 53, flows along the periphery of the liquid crystal light valve 34R, and flows out from the outflow portion (OUT). As described above, the liquid crystal light valves 34R, 34G, and 34B and the element cooling pipe 53 are disposed adjacent to each other, whereby the dispersion medium 23 that flows through the element cooling pipe 53 and the liquid crystal light valves 34R, 34G, and 34G. Heat exchange takes place at.

Further, the merging tank 55 merges the dispersion media 23 sent from the element cooling pipes 53 and temporarily accumulates them.
9 schematically shows the piping between the merging tank 55 and the diffusion plate 12 of the screen 10, the outflow part 55 </ b> A of the merging tank 55 and the inflow pipe 28 of the diffusing plate 12 of the screen 10 are connected via the pipe part 66. Has been. Further, the discharge pipe 29 of the diffusion plate 12 of the screen 10 and the inflow part 61 A of the tubular member 61 of the radiator 56 are connected via a pipe part 67.

As shown in FIG. 7, the radiator 56 includes a tubular member 61 through which the dispersion medium 23 flows and a plurality of radiating fins 62 connected to the tubular member.
The tubular member 61 is made of a member having high thermal conductivity such as aluminum, and the dispersion medium 23 that has flowed in from the inflow portion 61A flows through the inside toward the outflow portion 61B. Furthermore, the outflow part 61B of the tubular member 61 and the main tank 51 are connected via a pipe part 58.
The plurality of radiating fins 62 are made of a plate member having high thermal conductivity such as aluminum and are arranged in parallel. The axial fan 57 is configured to blow cooling air from one surface side of the radiator 56.
In the radiator 56, the heat of the dispersion medium 23 flowing in the tubular member 61 is radiated through the radiation fins 62, and the heat radiation is promoted by the supply of cooling air by the axial fan 57.

  As described above, in the liquid cooling unit 50, the dispersion medium is arranged in the order of the main tank 51, the fluid pumping unit 52, the branch tank 54, the element cooling pipe 53, the merging tank 55, the screen 10, and the radiator 56 via the pipe part 58. 23 flows, and the dispersion medium 23 returns from the radiator 56 to the main tank 51 and circulates repeatedly through the path.

Next, a method of projecting an image on the screen 10 by the rear projector 1 of the present embodiment having the above configuration will be described.
First, as shown in FIG. 6, the illuminance distributions of the laser beams emitted from the laser light sources (light source devices) 31R, 31G, and 31B are substantially uniformed by the illumination optical systems 32R, 32G, and 32B, respectively. Incident on 34R, 34G, and 34B. The incident laser light is modulated by the liquid crystal light valves 34R, 34G, and 34B, and enters the cross dichroic prism 36. Thereafter, the cross dichroic prism 36 combines the R light, the G light, and the B light modulated by the transmissive liquid crystal light valves 34R, 34G, and 34B. The light combined by the cross dichroic prism 36 is a projection lens 37. Is projected onto the screen 10.

At this time, as shown in FIG. 3, the laser light projected on the screen 10 is incident from the incident surface 11a of the Fresnel plate 11, refracted by the Fresnel lens 11c, and becomes parallel light. Then, the parallel light emitted from the exit surface 11 b of the Fresnel plate 11 is diffused in a random direction by the diffusion plate 12, and the diffused light enters from the entrance surface 13 a of the lenticular plate 13. Then, the light emitted from the lenticular plate 13 is diffused within a predetermined angle range. At this time, the dispersion medium 23 stored in the main tank 51 is sent to the fluid pressure feeding unit 52. Then, the dispersion medium 23 sent from the fluid pumping unit 52 to the branch tank 54 receives heat generated from the respective liquid crystal light valves 34R, 34G, and 34B. The warmed dispersion medium 23 is stored in the merging tank 55 and flows to the screen 10. Thereby, the dispersion medium 23 flows in the accommodation space K of the diffusion plate 12 of the screen 10. And the particle | grains 23b in the accommodation space K also flow, and the position of the particle | grains 23b in the whole accommodation space K changes every moment with the flow of this particle | grain 23b.
Along with this change, the speckle that is visually recognized moves, and the speckle pattern changes in a complex manner. As a result, the speckle pattern is integrated and averaged within the afterimage time of the human eye, and scintillation due to speckle is not visually recognized.
Further, the warmed dispersion medium 23 is radiated in the accommodation space K provided in the image display area A. The dispersion medium 23 is radiated by the radiator 56 and is stored in the main tank 51 again.

In the rear projector 1 according to the present embodiment, since the particles 23b in the accommodation space K of the diffusion plate 12 move with the flow of the dispersion medium 23, the scintillation generated between the screen 10 and the viewer is removed. There is no feeling of touch, the image by the projected light can be seen well, and the viewer's fatigue is also reduced. Further, since the scintillation can be removed without moving the diffusion plate 12 in the focus direction, image blur does not occur. Further, since there is no mechanical drive system, it is possible to provide the rear projector 1 that is advantageous in terms of durability.
Furthermore, since the dispersion medium 23 that has received heat flows into the accommodation space K of the diffusion plate 12 of the screen 10, a large heat radiation area can be obtained by the accommodation space K provided in the image display area A. Therefore, the liquid crystal light valves 34R, 34G, and 34B can be efficiently cooled.
That is, the rear projector 1 of the present embodiment can reliably prevent scintillation due to the projection light and improve the image quality.

Further, since the cooling medium 23a is a liquid, there is no possibility of dust and the like being mixed as compared with the case where gas is used as the cooling medium, so that a clear image can be displayed.
Further, in the image display area A where the image on the screen 10 is displayed, if the dispersion medium 23 is not flowed, there is a possibility that image quality is deteriorated due to the flow disturbance and a stagnation point is formed, thereby causing scintillation. is there. Therefore, in the present embodiment, the diffusing plate 12 is provided with the rectifying unit 40, so that the turbulence of flow and the occurrence of stagnation points are suppressed.
Furthermore, since the rectifying unit 40 is provided outside the image display area A, it does not affect the displayed image, so that a bright image can be displayed.

In addition, although it was set as the structure which provided the rectification | straightening part 40 in the upper end part 12a, the structure which provided the rectification | straightening part 40 in any of the upper end part 12a and the lower end part 12b may be sufficient. With this configuration, the inflow of the dispersion medium 23 into the accommodation space K and the discharge of the dispersion medium 23 from the accommodation space K can be performed smoothly.
Further, the flow direction of the dispersion medium 23 is forward with respect to gravity, that is, the direction from the upper end 12a to the lower end 12b of the diffusion plate 12, but the reverse direction (from the lower end 12b to the upper end 12a). Also good. Furthermore, as shown in FIG. 5, the dispersion medium 23 may flow toward the side surface portion 12 e opposite to the side surface portion 12 d (in the horizontal direction of the screen 10).
The shape of the through hole 41 is not limited to the above shape.
Further, the liquid crystal light valves 34R, 34G, 34B are cooled by the liquid cooling unit 50, but the polarizing plates (optical components) used for the laser light sources (optical components) 31R, 31G, 31B and the liquid crystal light valves 34R, 34G, 34B. In addition, a structure that cools a member that generates heat, such as a power source (not shown, an optical component) may also be used.
In addition, the radiator 56 may not be provided in the projection optical system 30 as long as the heat of the heated dispersion medium 23 on the screen 10 is sufficient. In this configuration, since the projection optical system 30 can be reduced in size, the entire rear projector 1 can be reduced in size.

Furthermore, since it is sufficient that the dispersion of the particles 23b in the dispersion medium 23 can be ensured only when the rear projector 1 is driven, there is no need for the particles 23b to be perfect without precipitation until the rear projector 1 is not driven. Wide selection of materials. Further, in order to ensure the dispersion of the particles 23b in the dispersion medium 23 in advance, before the image is projected by the projection optical system 30, a dispersion process for dispersing the particles 23b in the dispersion medium 23 or a flow of the dispersion medium 23 is performed. Even a configuration including a process for stabilizing the flow is effective in stabilizing the image quality.
Moreover, although the Fresnel board 11 and the lenticular board 13 were used as an angle conversion member, it does not restrict to this. That is, any member that can convert light incident on the screen 10 into a predetermined angle range may be used.
Further, if the Fresnel plate 11 and the lenticular plate 13 are not used, the gain (brightness) of the screen 10 becomes small. However, since a screen that can be seen by an observer in a wider direction places importance on diffusibility, a diffusing surface is required, so the Fresnel plate 11 and the lenticular plate 13 are not necessarily required.
Further, a heat radiating fin (heat radiating member) capable of radiating heat may be provided outside the image display area A, for example, on a fixed frame of the screen 10 to further enhance heat radiating on the screen 10.
Further, although the rectifying unit 40 is provided outside the image display area A, the rectifying unit 40 is provided in the image display area A as long as the rectifying unit 40 and the sealing material 24 are members having optical transparency. May be.

[Modification of First Embodiment]
In the first embodiment shown in FIG. 1, the rectifying unit 40 has a plurality of through holes 41, but a diffusing plate 65 having sponge foams 68 and 69 may be used instead of the rectifying unit 40. . Such a modification will be described with reference to FIG. In addition, the structure of the other screen 10 is the same as that of 1st Embodiment.

As shown in FIG. 10, the diffusion plate 65 is provided with a sponge foam (porous member) 68 into which the cooling medium 23 a in the flow path 26 flows into the upper end portion 12 a of the accommodation space K. A sponge foam (porous member) 69 is also provided at the discharge port 12 c of the lower end 12 b of the diffusion plate 12. The sponge foams 68 and 69 are made of a porous resin material having a plurality of holes. If the diameter of the holes is too small, the cooling medium 23a cannot be smoothly transmitted. Therefore, it is preferable that the particle size is slightly smaller than the particle size of the particles 23b to be used.
Thereby, the particles 23b arranged in the accommodation space K can be kept only in the accommodation space K. That is, only the cooling medium 23a flows out from the outlet 12c of the diffusion plate 65.

  In the projector having such a diffusion plate 65, the particles 23 b do not flow out of the accommodation space K due to the sponge foams 68 and 69. Therefore, since the particles 23b do not flow out to the discharge port 12c, it is possible to avoid the possibility that the particles 23b are clogged in the pipe portions 58, 66, 67 and the like of the liquid cooling unit 50. That is, the cooling medium 23a can be reliably circulated in the accommodation space K.

In this modification, the fluid pumping unit 52 is reversed every predetermined time so that the particles 23b do not collect near the sponge foam 69 of the discharge port 12c, and the dispersion medium 23 flows from the inlet pipe 28 to the outlet pipe 29. And the flow from the discharge pipe 29 to the inflow pipe 28 may be switched at regular intervals.
Alternatively, the fluid pumping unit 52 may cause the dispersion medium 23 to flow from the lower end 12b side to the upper end 12a side of the diffusion plate 12, and the fluid pumping unit 52 may be stopped after a predetermined time has elapsed. Thereby, the particles 23b accumulated near the sponge foam 68 on the upper end portion 12a side of the diffusion plate 12 fall to the lower end portion 12b side of the diffusion plate 12 due to gravity. With these configurations, the particles 23b can be evenly dispersed in the accommodation space K.
Moreover, the rectification | straightening part 40 as shown in 1st Embodiment may be provided in the diffusion plate 65 of this modification.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIGS. In each embodiment described below, portions having the same configuration as those of the rear projector 1 according to the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
In the projection system 70 according to the present embodiment, as shown in FIG. 11, the screen 80 and the projection engine 71 are configured separately. Moreover, the optical member and optical system which comprise the projection engine 71 are the same as that of 1st Embodiment.

As shown in FIG. 12, the screen 80 includes a diffusion plate 81 and heat radiating fins (heat radiating members) 90. In the screen 80 shown in FIG. 12, the Fresnel plate 11 and the lenticular plate 13 are omitted.
The diffusion plate 81 includes a light transmission plate 82 disposed on the viewing side, a reflection plate 83 disposed on the back side when viewed from the viewing side, and the dispersion medium 23. The diffusion plate 81 is provided with a space sealed by a packing (sealing material) 84 provided along the peripheral edge between the transmission plate 82 and the reflection plate 83. It is a storage space K in which the medium 23 is stored. Note that the transmission plate 82 and the reflection plate 83 may be fixed by a fixed frame.

The reflection plate 83 is a reflection mirror that reflects light transmitted through the transmission plate 82 and passed through the dispersion medium 23 toward the transmission plate 82. If the reflecting plate 83 has the same shape of the Fresnel plate 11 as in the first embodiment, the gain of the screen 80 increases. Further, if the reflector 83 has the same shape of the lenticular plate 13 as that of the first embodiment, which is a diffusing member, the viewing angle can be widened.
Further, the screen 80 is provided with heat radiating fins 90 on a surface 83b of the reflector 83 opposite to the surface 83a that contacts the dispersion medium 23. The heat radiating fin 90 has a plurality of plate-like members 90 a and is exposed to the outside (on the opposite side to the side on which image light is incident) at a position corresponding to the image display area A of the transmission plate 82. Further, it is preferable to use a metal material having good conductivity as the material of the heat radiation fin 90. For example, you may form with raw materials, such as aluminum, aluminum alloy, copper alloy, or stainless steel.

Further, the screen 80 is provided with a rectifying unit 86 in which a flow path 85 and a through hole 86a similar to those of the first embodiment are formed. Further, an inflow pipe 87 that communicates with the flow path 85 and allows the dispersion medium 23 to flow into the accommodation space K is provided on the upper end portion 83c side of the reflection plate 83 of the screen 80, and the accommodation space is provided on the lower end portion 83d side. A discharge pipe 88 for discharging the dispersion medium 23 in K is provided.
Further, the projection engine 71 is a polarizing plate used for the laser light sources (optical components) 31R, 31G, 31B, the liquid crystal light valves (optical components) 34R, 34G, 34B, and the liquid crystal light valves 34R, 34G, 34B shown in FIG. (Optical component) and the heat generated from the power source (not shown, optical component) are configured so that the dispersion medium 23 receives heat.

As shown in FIG. 11, the outflow portion 55 </ b> A of the projection engine 71 and the inflow pipe 87 of the screen 80 are connected by a tube (communication portion) 72. Further, the discharge pipe 88 of the screen 80 and the inflow part 61 </ b> A of the projection engine 71 are communicated by a tube (communication part) 73.
As a result, the dispersion medium 23 received by the projection engine 71 flows out from the projection engine 71 via the tube 72 and can flow into the accommodation space K from the inflow pipe 87 of the screen 80. The dispersion medium 23 radiated from the screen 80 flows out from the discharge pipe 88 of the screen 80 via the tube 73 and can flow into the projection engine 71.

In the projection system 70 according to the present embodiment, since the cooling medium 23a is radiated by the screen 80, the heat radiation area can be greatly increased. That is, in a normal projection system, the casing of the projection engine 71 is given a heat radiation shape, or a dedicated heat sink is installed. Thereby, since the area cannot be made large due to the size restriction of the projection engine 71, the cooling effect is small. However, in the projection system 70 of the present embodiment, the cooling effect is increased, the air volume by a large fan is not required, and it is possible to achieve calmness.
In addition, a radiating fin can be provided only outside the image display area A in a transmissive screen. However, since the reflection type screen 80 of the present embodiment is provided with the radiation fins 90 so as to cover the image display area A, it is possible to dissipate the warmed cooling medium 23a with an overwhelmingly large radiation area. Become.
In this way, by providing a heat dissipation shape on the screen 80 side, not only can the heat dissipation area be increased, but a cooling fan is provided at a position away from the observer, or a cooling fan is not used. The cooling medium 23a can be sufficiently cooled. Therefore, it is possible to solve the problem that there is a noise source near the observer, which is the biggest drawback of the projection system.

Even if the projection engine 71 includes a fan, the projection system 70 according to the present embodiment has a sufficient heat dissipation effect even without a fan. Therefore, even a quiet fan with a small air volume and sufficient cooling of the cooling medium 23a. An effect can be obtained.
Further, for example, when the positions of the screen 80 and the projection engine 71 in the room are fixed, the tubes 72 and 73 may be disposed inside the wall or floor (position where the observer cannot see). . Furthermore, the projection engine 71 which has the connector part which exposes the front-end | tip part of a tube, for example from a wall, and can be connected with the front-end | tip of a tube may be sufficient. As a result, only when the image is projected from the projection engine 71 onto the screen 80, the distal end portion of the tube and the connector portion of the projection engine need only be connected.
Further, although the dispersion medium 23 is configured to receive heat generated from the laser light sources 31R, 31G, and 31B, the liquid crystal light valves 34R, 34G, and 34B, the polarizing plate, and the power source, only the member that generates a large amount of heat is cooled. There may be.
Further, in the present embodiment, the screen 80 having the rectifying unit 40 similar to that in the first embodiment is used, but a screen having sponge foams 68 and 69 similar to the modification of the first embodiment may be used.

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.
The specific configuration of the scattering plate exemplified in the above embodiment is 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 reflective light modulation element such as a DMD (Digital Micromirror Device) element in addition to a liquid crystal light valve as a light modulation means. . For example, the present invention can be applied not only to a three-plate projector as in the above embodiment, but also to a single-plate (time division) projector.

The order of arrangement of the Fresnel plate, the diffusion plate, and the lenticular plate is not limited to the above arrangement. Further, the screen does not need to be composed of three layers of a Fresnel plate, a diffusion plate, and a lenticular plate, and may have a two-layer structure in which the diffusion plate is included in any one of the Fresnel plate and the lenticular plate. That is, a configuration in which a refrigerant and particles are provided in any one of a Fresnel plate and a lenticular plate and fluidized by a fluid pumping unit may be used.
In addition, although the particles are prevented from sinking depending on the conditions such as the cooling medium, the material of the particles, and the size and weight of the particles, the particles are sandwiched between the first substrate and the second substrate in order to prevent further precipitation of the particles. The region may be divided into a plurality of regions. In this configuration, since the particles in the refrigerant move within a predetermined region, it is possible to prevent the particles from settling on the lower end side of the diffusion plate, and to disperse the particles uniformly in the refrigerant.
As a specific means for realizing this, for example, a configuration in which a plurality of microcapsules are used and a plurality of particles are provided in the microcapsules may be used.

Moreover, although it demonstrated using the Fresnel board, it should just have a refracting action which refracts | emits the incident light not only in this, For example, a hologram sheet etc. may be sufficient.
Furthermore, the lenticular plate on which the bowl-shaped microlens element is formed is used. However, the present invention is not limited to this. For example, when the lenticular plate is viewed in plan, a microlens element having a substantially circular or substantially elliptical shape is formed. It may be an optical element. Moreover, the optical member should just be a plate-shaped member which has a light transmittance, for example, glass etc. may be sufficient as it.

Further, although a laser light source having high coherence is used as the light source, any light source having coherence is effective, and the light source may be, for example, a high-pressure mercury lamp, LED, or the like.
Moreover, although the liquid was used as the refrigerant, the particles may be evenly dispersed in the accommodation space using a gas. By using the gas in this way, bubbles may be mixed in the liquid. However, if the cooling medium is a gas, there is no risk of bubbles being mixed. Therefore, since there is no deterioration of the image due to bubbles, a clear image can be displayed.
Moreover, although the flow of the refrigerant on the projection optical system side and the flow of the refrigerant in the screen are performed by one fluid pumping unit, the fluid pumping unit may be provided individually. In this configuration, the flow means on the screen 10 side may be driven in synchronization with the power supply of the projector.
Further, the rear projector of the first embodiment may be provided with heat radiating fins. In that case, the heat dissipating fins are disposed outside the image forming area. Further, heat radiating fins may be provided outside the image display area of the reflective screen of the projection system 70.
Further, although the 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, 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.

1 is a schematic configuration diagram of a projector according to a first embodiment of the invention. It is a perspective view which shows schematic structure of the screen of the projector of FIG. It is principal part sectional drawing which shows the screen of the projector of FIG. It is a principal part cross-section perspective view which shows the light-diffusion layer of the screen of the projector of FIG. It is sectional drawing which shows the light-diffusion layer of the screen of the projector of FIG. It is a schematic block diagram of the projection optical system of the projector of FIG. It is a perspective view which shows the liquid cooling unit of the projector of FIG. FIG. 2 is a plan view and a main part sectional view showing cooling of the light modulation means of the liquid cooling unit of the projector of FIG. 1. It is a schematic diagram which shows piping of the liquid cooling unit and screen of the projector of FIG. It is sectional drawing which shows the modification of the light-diffusion layer of the projector which concerns on 1st Embodiment of this invention. It is a schematic block diagram of the projection system which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the light-diffusion layer of the screen of the projector of FIG. It is a figure which shows the principle of scintillation.

Explanation of symbols

  A ... Image display area (image forming area), K ... Accommodating space, 1 ... Rear projector (projector), 10, 80 ... Screen, 12, 65, 81 ... Diffusion plate (light diffusion layer), 23a ... Cooling medium, 26 , 85 ... flow path, 31R, 31G, 31B ... light source, 34R, 34G, 34B ... liquid crystal light valve (light modulation means), 37 ... projection lens (projection means), 40, 86 ... rectifying part, 52 ... fluid pressure sending part , 68, 69 ... sponge foam (porous member), 70 ... projection system, 71 ... projection engine, 72, 73 ... tube (communication part), 90 ... radiation fin (heat radiation member)

Claims (9)

A light source that emits light;
Light modulating means for modulating light emitted from the light source according to an image signal;
A cooling medium that receives heat generated from any optical component;
A screen having a light diffusion layer for diffusing incident light;
Projecting means for projecting the light modulated by the light modulating means onto the screen;
The light diffusing layer has a storage space in which a light scattering material is movably dispersed, and the cooling medium flows in the storage space.   The projector according to claim 1, wherein the cooling medium is a liquid.   The projector according to claim 1, wherein the cooling medium is a gas.   The projector according to any one of claims 1 to 3, wherein the light diffusion layer is provided with a rectification unit that rectifies the flow of the cooling medium.   The projector according to claim 4, wherein the housing space is provided with a porous member that is made of a porous material, allows the cooling medium to pass therethrough, and prevents the light scattering material from passing therethrough. .   The projector according to any one of claims 1 to 5, wherein the screen includes an angle conversion member that converts an angle of incident light. A screen for use with a projection engine with a cooling medium,
A light diffusion layer for diffusing the light emitted from the projection engine;
The screen, wherein the light diffusing layer is provided in at least an image forming region and has a receiving space in which the cooling medium is stored and a movable light scattering material is dispersed.   The screen according to claim 7, wherein a heat radiating member exposed to the outside is provided at least in the image forming area. A projection engine;
The screen according to claim 7 or 8, wherein the projection light emitted from the projection engine is projected;
A projection system comprising: a communication portion into which the cooling medium is introduced to communicate between the accommodation space and the projection engine.

Images