JP2008151914A - Screen, projector and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screen capable of achieving high image quality by restraining noise or vibration or the like and surely preventing scintillation by projected light, and a projector and an image display device. <P>SOLUTION: The screen is equipped with: a light diffusing plate 12 where movable light scattering material is dispersed in a medium provided between a first substrate and a second substrate, and at least either of the first substrate or the second substrate has light transmissibility; and a vibration imparting means which imparts vibration to the light diffusing plate 12. At least either of the first substrate or the second substrate is an elastic body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  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. 11, 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.

  As a countermeasure for reducing such scintillation, a technique for selectively integrating and averaging the interference spot components spatially or temporally in a projection system, particularly a screen, arranged at the rear stage of the light valve (see, for example, Patent Document 1). .) Is disclosed.

In addition, the image projection screen described in Patent Document 1 temporally changes the scattering distribution and / or phase of scattered waves in a light diffusion plate constituting the screen. In this way, the scattering state is changed by moving a part or the whole of the screen structure, and time integration is performed by the afterimage effect of the eye, thereby suppressing the generation of speckle.
JP 2001-100316 A

  However, in Patent Document 1, 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 transfer efficiency to the scattering layer is low, and vibrations, sounds, unnecessary electromagnetic waves, exhaust heat, etc. that occur when moving the screen may occur, which may hinder comfortable viewing. is there.

  The present invention has been made to solve the above-described problems, and is a screen, projector, and image display capable of suppressing noise, vibration, and the like, reliably preventing scintillation due to projection light, and achieving high image quality. An object is to provide an apparatus.

In order to achieve the above object, the present invention provides the following means.
In the screen of the present invention, a movable light scattering material is dispersed in a medium provided between the first substrate and the second substrate, and at least one of the first substrate and the second substrate is light transmissive. And a vibration applying means for applying vibration to the light diffusion plate, and at least one of the first substrate and the second substrate is an elastic body.

In the screen according to the present invention, since at least one of the first substrate and the second substrate is an elastic body, one of the first substrate and the second substrate swings as a whole by driving the vibration applying means. With the movement of the substrate, the light scattering material in the medium can be moved (vibrated). That is, since at least one of the first substrate and the second substrate is an elastic body, the substrate made of the elastic body vibrates randomly (irregularly). As a result, the medium swings, so that the light scattering material in the medium also moves randomly.
Thereby, since light is irradiated to the light diffusion material moved to various positions in the medium, the diffusion state of the light emitted from the diffusion layer is temporally changed. Therefore, the speckle pattern of the light emitted from the diffusing member changes with time and is time-integrated by the afterimage effect. As a result, the light emitted from the screen becomes light with reduced scintillation and is of good quality. An image can be displayed.
Furthermore, since the screen of the present invention does not move the layers constituting the screen but moves the light scattering material in the medium, noise and vibration can be suppressed. Therefore, it is possible to comfortably view high-quality images.

  Moreover, it is preferable that the screen of this invention is provided with the control part which controls the said vibration provision means so that the said light-scattering material can move continuously.

  In the screen according to the present invention, the vibration applying means is controlled by the control unit, and the light scattering material in the medium continuously moves along a circular or elliptical or elliptical orbit. In this way, by continuously moving (swinging) the light scattering material, the light scattering material does not have a dead point (a point where the movement stops for a moment), and therefore there is no moment of interference even for a moment. Therefore, the effect of suppressing speckle like flicker (flickering of the image on the screen) can be continuously maintained.

In the screen of the present invention, it is preferable that the vibration applying means is provided outside the image forming area of the light diffusion plate.
In the screen according to the present invention, since the vibration applying means is provided outside the image forming area, light passes through the image forming area particularly in the case of a transmissive screen, but the vibration applying means is disposed at any position. However, since the displayed image is not affected, a clear image can be displayed.

In the screen of the present invention, it is preferable that the medium has viscosity.
In the screen according to the present invention, since the medium has viscosity, the vibration applied to the light diffusing plate by the vibration applying means is easily propagated to the medium, and the vibration is maintained for a predetermined time. Therefore, since the vibration of the medium is slowly attenuated, the light diffusing material in the medium can be efficiently vibrated.

  In the screen of the present invention, it is preferable that the vibration applying means is driven intermittently at a predetermined time interval.

In the screen according to the present invention, since at least one of the first substrate and the second substrate is an elastic body, after driving the vibration applying unit and moving (vibrating) the light diffusion plate, the driving of the vibration applying unit is stopped. Even so, the elastic substrate continues to shake. The elastic substrate continues to vibrate for a certain period of time, and then the vibration is attenuated. However, since the vibration applying means is driven at predetermined time intervals, the light diffusion plate moves (vibrates) again. In this way, by driving the vibration applying means at predetermined time intervals, the light scattering material in the medium can be moved (vibrated), so that the drive energy of the vibration applying means can be suppressed. That is, it is possible to save power for driving the vibration applying means.
Further, by driving the vibration applying unit at predetermined time intervals, it is possible to further reduce the sound resulting from the driving of the vibration applying unit.

In the screen of the present invention, the predetermined time interval is preferably random.
In the screen according to the present invention, the interval at which the vibration applying unit is driven is random (irregular), that is, since the drive of the vibration applying unit is not constant, the movement (vibration) of the light scattering member in the medium is random. It will increase the nature. Therefore, scintillation of light emitted from the screen is further suppressed, and a higher quality image can be displayed.

In the screen of the present invention, it is preferable that the vibration applying means is an ultrasonic vibrator.
In the screen according to the present invention, since the vibration applying means is an ultrasonic vibrator, the response is good and the operation is quiet, so that the generation of sound and vibration can be suppressed. Therefore, it is possible to prevent the generation of noise accompanying the driving of the driving means and to provide a screen with high silence.

The screen of the present invention is preferably an actuator in which the vibration applying means reciprocates.
In the screen according to the present invention, for example, a small solenoid can be used as the vibration applying means, so that the entire screen can be reduced in size.

  A projector according to the present invention includes a light source device that emits light, a light modulation device that modulates light emitted from the light source device according to an image signal, and a projection device that projects light modulated by the light modulation device. And the above-mentioned screen on which an image emitted from the projection device is projected.

  In the projector according to the present invention, the light emitted from the light source device enters the light modulation device. Then, the image modulated by the light modulation device is projected onto the screen by the projection device. At this time, since a screen in which scintillation is reduced while suppressing noise, vibration, and the like is used, the image projected from the screen has no luminance unevenness and a high-quality image is displayed.

  An image display device of the present invention includes a light source device that emits light, a scanning unit that scans laser light emitted from the light source device, and the screen that projects the light scanned by the scanning unit. An image display device characterized by that.

  In the image display device according to the present invention, the light emitted from the light source device is scanned by the scanning means. The light scanned by the scanning unit is projected on the screen. At this time, since a screen that reduces image blurring while reducing scintillation is used, generation of scintillation is suppressed for light emitted from the screen. Therefore, it is possible to display a high-quality image without luminance unevenness.

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

[First Embodiment]
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.

Next, a schematic configuration of the projection optical system 30 of the rear projector 1 will be described.
FIG. 2 is a schematic diagram showing the configuration of the projection optical system 30 of the rear projector 1. In FIG. 2, 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 device) 31R that emits red light, a green laser light source (light source device) 31G that emits green light, and a blue laser light source (laser light source) 31B that emits blue light. The liquid crystal light valves (light modulation devices) 34R, 34G, 34B for modulating the laser light emitted from these laser light sources 31R, 31G, 31B and the laser light modulated by the liquid crystal light valves 34R, 34G, 34B are combined. A cross dichroic prism (color light combining means) 36 and a projection lens (projection device) 37 that enlarges and projects the laser light combined by the cross dichroic prism 36.

  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.

Next, details of the screen 10 will be described.
As shown in FIG. 3, the screen 10 is arranged between the Fresnel plate 11 that converts the angle of incident light, the transmissive lenticular plate 13, and the Fresnel plate 11 and the lenticular plate 13. And a diffusion plate (light diffusion plate) 12 for diffusing light. Moreover, the screen 10 is provided with the vibration supply part 14 which vibrates the diffusion plate 12, as shown in FIG. An opening 2a is formed on the front surface of the housing 2, and the screen 10 is fitted in the opening 2a.

First, the diffusion plate 12 will be described.
As shown in FIG. 3, 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. 5, 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 1st board | substrate 21 has a light transmittance, for example, is a glass plate. The material of the first substrate 21 is, for example, polycarbonate, cycloolefin-based resin, and the like, in addition to being transparent, it has properties such as low hygroscopicity, heat resistance, low birefringence, and high dimensional stability. It is preferable to be comprised with a material. The second substrate 22 is made of an elastic body (for example, silicon rubber). Further, a vibration supply unit 14 is provided on the upper end surface 12 a of the diffusion plate 12.

The dispersion medium 23 is sealed between the first substrate 21 and the second substrate 22 by a sealing material 24 provided along the peripheral edge.
The dispersion medium 23 includes a solvent (medium) 23a and diffusible particles (light scattering material) 23b provided inside the solvent 23a. The particles 23b can continue to be dispersed without sinking depending on conditions such as the material of the solvent 23a and the particles 23b and the size and weight of the particles 23b. The solvent 23a is preferably made of a light-transmitting material. For example, a non-electrically conductive organic solvent is used, and a surfactant that promotes charging of the particles 23b is added to the solvent 23a. Has been. Further, a substance for facilitating charging is added to the particles 23b.

  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.

Next, the vibration supply unit 14 will be described.
As shown in FIG. 6, the vibration supply unit 14 includes an ultrasonic vibration element (vibration applying unit) 15 that generates ultrasonic waves, and a control unit 16 that controls the ultrasonic vibration element 15. The ultrasonic vibration element 15 has the same length as the horizontal length of the diffusion plate 12. Further, the plurality of ultrasonic vibration elements 15 are connected to an oscillation circuit 17 controlled by the control unit 16. Thereby, an oscillation signal of the oscillation circuit 17 is generated by the control signal of the control unit 16, and the ultrasonic vibration element 15 generates an ultrasonic wave.
Further, the ultrasonic vibration element 15 is made of a plate-shaped piezoelectric ceramic, and is in contact with the upper end surface 21a of the first substrate 21, the sealing material 24, and the upper end surface 22a of the second substrate 22, as shown in FIG. Is provided. The ultrasonic transducer 15 is fixed to the opening 2 a of the housing 2.
The frequency of the ultrasonic wave generated by the ultrasonic vibration element 15 is, for example, 100 kHz.

Although there are a plurality of driving patterns of the ultrasonic vibration element 15 by the control unit 16, the relationship between the driving of the ultrasonic vibration element 15 as an example and time will be described with reference to a timing chart shown in FIG.
As shown in FIG. 7, a voltage is applied to the ultrasonic transducer 15 with a predetermined time interval. That is, since the second substrate 22 is made of an elastic body, even if the driving by the ultrasonic vibrator 15 stops, the second substrate 22 can continue to shake for a predetermined time. Can be driven.

The drive start time of the ultrasonic transducer 15 is S1, the drive start time of the second ultrasonic transducer 15 is S2, the drive start time of the third ultrasonic transducer 15 is S3, and the fourth The driving start time of the ultrasonic vibration element 15 is S4. At this time, the time interval between time S1 and time S2 is t1, the time interval between time S2 and time S3 is t2, and the time interval between time S3 and time S4 is t3. At this time, the ultrasonic vibration element 15 is driven at different time intervals t1, t2, and t3, that is, non-constant time intervals.
The time intervals t1, t2, and t3 are longer than the time from when the second substrate 22 starts to vibrate due to one driving of the ultrasonic vibration element 15 until the second substrate 22 attenuates. Thereby, in the control part 16, before the 2nd board | substrate 22 stops, the 2nd board | substrate 22 is vibrated by the ultrasonic vibration element 15 again.
Further, the control unit 16 drives the ultrasonic vibration element 15 so that no node is generated in the vibration of the second substrate 22. Note that the control unit 16 may control the nodes generated by the vibration of the second substrate 22 to move.

  Thereby, the 2nd board | substrate 22 which consists of an elastic body of the diffusion plate 12 of the screen 10 vibrates randomly (irregularly), as shown in FIG. Due to the vibration of the second substrate 22, the solvent 23a vibrates, and the particles 23b in the solvent 23a also vibrate randomly. In this way, the particles 23b move due to the generation of ultrasonic waves by the ultrasonic vibrator 15.

Next, the Fresnel plate 11 will be described.
As shown in FIG. 4, the Fresnel plate 11 has 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 laser light emitted from the projection lens 37 and incident from the incident surface 11a, converts the laser light into parallel light, and emits the light from the exit surface 11b.
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. 4, the lenticular plate 13 is provided with a plurality of bowl-shaped microlens elements 13c on the incident surface 13a on the incident side of the laser beam. 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.
Further, the lenticular plate 13 diffuses the laser light incident from the incident surface 13a within a predetermined angle range and emits it from the emission surface 13b, widens the viewing angle of the image, and moves the screen 10 horizontally from the front. A good image can be observed even when observed at a shifted position. 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 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. 2, the illuminance distributions of the laser beams emitted from the laser light sources 31R, 31G, and 31B are substantially uniformed by the illumination optical systems 32R, 32G, and 32B, respectively, and the liquid crystal light valves 34R, 34G, and 34B is incident. 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.

  When the progress of the laser light is schematically shown, the laser light projected on the screen 10 is incident from the incident surface 11a of the Fresnel plate 11 and is refracted by the Fresnel lens 11c to become parallel light as shown in FIG. 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, since the ultrasonic vibrator 15 is controlled by the control unit, the second substrate 22 vibrates with the vibration of the ultrasonic vibrator 15. The vibration of the second substrate 22 is transmitted to the particle 23b, and the particle 23b moves (vibrates) in the solvent 23a. In this way, the particles 23b of the entire screen 10 move (vibrate).

In the screen 10 according to the present embodiment, since the second substrate 22 is made of an elastic body, it vibrates randomly (irregularly), so that the solvent 23a rocks randomly. Along with this, the particles 23b in the solvent 23a also move randomly, so that the diffusion state of the light emitted from the diffusion plate 12 changes with time. In this way, the speckle pattern of the light emitted from the diffusion plate 12 is integrated by the afterimage effect, and becomes light with suppressed scintillation. Further, since the light emitted from the screen 10 is light with suppressed scintillation, it is possible to provide the rear projector 1 that displays a high-quality image.
In addition, since the second substrate 22 is made of an elastic body, it is not necessary to always drive the second substrate 22, so that the particles 23 b in the solvent 23 a can be efficiently moved continuously without consuming excess energy. Is possible. Therefore, it is possible to realize power saving by driving the ultrasonic vibration element 15 intermittently.

Further, since the second substrate 22 on the side far from the observer is an elastic body and the first substrate 21 on the side near the observer does not vibrate, the viewer can more comfortably appreciate the image emitted from the screen 10. It becomes possible.
Furthermore, since the time intervals t1, t2, and t3 are longer than the time until the second substrate 22 starts to vibrate and attenuates due to one driving of the ultrasonic vibration element 15, before the second substrate 22 stops. In addition, the second substrate 22 is vibrated again by the ultrasonic vibration element 15. Thereby, since the particles 23b in the solvent 23a continuously move (vibrate), the particles 23b do not have a dead point (a point at which the movement stops even for a moment), and thus there is no moment of interference even for a moment. Therefore, the effect of suppressing speckle like flicker (flickering of the image on the screen) can be continuously maintained.
That is, the screen 10 of the present embodiment can suppress noise, vibration, and the like, reliably prevent scintillation due to projection light, and achieve high image quality.

In addition, the solvent 23a may have viscosity. By forming the solvent 23a from a highly viscous material, the solvent 23a itself has elasticity, so that the ultrasonic waves generated from the ultrasonic vibration element 15 are easily propagated to the solvent 23a. Moreover, as the solvent 23a, for example, a transparent medium having a large viscosity selection range such as silicon oil can be used. Even if the solvent 23a is made of a material having a low viscosity, if at least one of the first and second substrates 21 and 22 has good elasticity, the attenuation rate is lowered, so that the entire substrate has a certain attenuation. The same effect can be expected because of the behavior.
As a result, the solvent 23a continues to vibrate for a predetermined time and slowly attenuates, and therefore exhibits good attenuation characteristics. Therefore, since the vibration of the medium slowly attenuates, the ultrasonic transducer 15 can be driven at a time interval longer than the time intervals t1, t2, and t3 shown in the present embodiment. Accordingly, since the particles 23b in the solvent 23a can be vibrated more efficiently, it is possible to save power by driving the ultrasonic vibration element 15.
Further, the first substrate 21 may be an elastic body, and any of the first substrate 21 and the second substrate 22 may be an elastic body. Since the first and second substrates 21 and 22 have elastic bodies, the vibration of the solvent 23a is attenuated more slowly. Accordingly, since the ultrasonic vibration element can be driven at a longer time interval, further power saving can be achieved.
Further, although the ultrasonic vibration element 15 is driven at a non-constant time interval as in the present embodiment, the ultrasonic vibration element 15 may be driven at a constant interval. In this configuration, the control of the ultrasonic vibration element 15 by the control unit 16 becomes easy.

  Further, although the ultrasonic vibration element 15 is used as the vibration applying means, the present invention is not limited to this as long as the diffusion plate 12 can be vibrated. For example, the vibration applying means may be an actuator that reciprocates. In this configuration, for example, a small solenoid can be used as the vibration applying means, so that the entire screen can be reduced in size. Further, as the actuator, the diffusion plate 12 may be vibrated by using a lead screw (ball screw) that moves the crank by attaching an eccentric shaft to the motor.

Moreover, the ultrasonic transducer | vibrator 15 may be provided in each end surface along the outer peripheral end surface of the diffusion plate 12. FIG. Furthermore, the structure by which the some ultrasonic vibration element is arrange | positioned for every end surface may be sufficient. In this configuration, by controlling the plurality of ultrasonic transducers 15 by the control unit 16, in addition to the circular orbit described above, the particles 23b can be continuously moved along an elliptical orbit, a random orbit, or a Brownian motion. It becomes possible. Further, the ultrasonic transducer 15 may be arranged so that vibration is applied in an oblique direction with respect to the end surface of the second substrate 22. Thereby, it becomes easy to produce a circular orbit in the particle 23b in the solvent 23a.
Further, the constituent material of the ultrasonic vibration element 15 as the vibration applying means is not particularly limited, but other than lead zirconate titanate (PZT), for example, quartz, lithium niobate, barium titanate, lead titanate, metaniobium Various materials such as lead acid, polyvinylidene fluoride, lead zinc niobate, and lead scandium niobate are preferably used.

Furthermore, although the transmissive screen 10 has been described as an example in the present embodiment, it can also be applied to a reflective screen. For example, as a configuration of the reflective screen, as shown in FIG. 9, the Fresnel plate 11, the lenticular plate 13, and the diffusion plate 12 are arranged in the order in which the light emitted from the projection lens 37 enters. At this time, the reflecting portion 20 is formed on the surface of the second substrate 22 that contacts the dispersion medium 23, and the light incident on the screen is reflected. Therefore, light does not pass through to the second substrate 22 side, and it is not necessary to provide the ultrasonic transducer 15 outside the image display area A. Thus, when used in a reflective screen, the degree of freedom of arrangement of the ultrasonic transducer 15 increases.
Further, in the reflection type screen, the second substrate 22 does not need to have light transmittance, and may have light shielding properties.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIG.
The image display device according to the present embodiment is obtained by applying the screen 10 according to the first embodiment to an image display device.
As shown in FIG. 10, the image display apparatus 100 includes a laser light source 102 </ b> R that emits R light, a laser light source 102 </ b> G that emits G light, a laser light source 102 </ b> B that emits B light, and a collimating optical system 104. And a lens optical system 103 including a beam shaping optical system 105, a scanner (scanning means) 106 that scans the incident laser light in a two-dimensional direction, and a projection lens 108 that enlarges and projects the laser light scanned by the scanner 106 The reflection mirror 109 reflects the light projected by the projection lens 108 toward the screen 10. In this image display device 100, the light source device 101, the lens optical system 103, the scanner 106, the projection lens 108, and the reflection mirror 109 are accommodated in a housing 110 having a screen 10 and run inside the housing 110. An image is displayed by scanning the laser beam on the screen 10.

  Since the image display device according to the present invention uses the screen 10 with reduced scintillation while suppressing noise, vibration, and the like, the light emitted from the screen 10 can suppress the occurrence of scintillation. Therefore, it is possible to display a high-quality image without luminance unevenness.

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, 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 solvent and particles are provided in any one of a Fresnel plate and a lenticular plate and is vibrated by a vibration applying unit may be employed.
Further, although the particles are prevented from sinking depending on the conditions such as the solvent, the material of the particles, and the size and weight of the particles, the region sandwiched between the first substrate and the second substrate in order to prevent the particles from further sinking. May be partitioned into a plurality of regions. In this configuration, the particles in the solvent move (vibrate) in a predetermined area, so that the particles can be prevented from settling on the lower end side of the diffusion plate, and the particles can be uniformly dispersed in the solvent. It becomes.
Furthermore, the structure which provided several particle | grains in the microcapsule using the several microcapsule may be sufficient.

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.
Although a transmissive liquid crystal light valve is used as the light modulation device, a reflective liquid crystal light valve and a micromirror array device can be used as the light modulation element. In that case, the configuration of the projection optical system is appropriately changed.

1 is a schematic configuration diagram of a projector according to a first embodiment of the invention. It is a schematic block diagram of the projection optical system of the projector of this 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-sectional perspective view which shows the vibration provision means of the screen of the projector of FIG. It is a top view which shows the screen of the projector of FIG. FIG. 2 is a timing chart showing driving timing of screen vibration applying means of the projector of FIG. 1. FIG. It is a top view which shows the flow of the solvent of the screen of the projector of FIG. It is sectional drawing which shows an example of the reflective screen of the projector which concerns on 1st Embodiment of this invention. It is a schematic block diagram of the image display apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the principle of scintillation.

Explanation of symbols

  A ... image display area (image forming area), 1 ... rear projector (projector), 10, 40, 50 ... screen, 12 ... diffusion plate (light diffusion plate), 15 ... ultrasonic transducer, 16 ... control unit, 21 ... 1st board | substrate, 22 ... 2nd board | substrate, 23a ... Solvent (medium), 23b ... Particle | grains (light-scattering material), 31R, 31G, 31B ... Laser light source (light source device), 34R, 34G, 34B ... Liquid crystal light valve ( Light modulation device), 37 ... Projection lens (projection device), 100 ... Image display device, 101 ... Light source device

Claims (10)

A light diffusing plate in which a movable light scattering material is dispersed in a medium provided between the first substrate and the second substrate, and at least one of the first substrate and the second substrate is light transmissive; ,
Vibration applying means for applying vibration to the light diffusion plate,
At least one of the first substrate and the second substrate is an elastic body.   The screen according to claim 1, further comprising a control unit that controls the vibration applying unit so that the light scattering material is continuously movable.   The screen according to claim 1, wherein the vibration applying unit is provided outside an image forming area of the light diffusing plate.   The screen according to any one of claims 1 to 3, wherein the medium has viscosity.   The screen according to any one of claims 1 to 4, wherein the vibration applying means is driven intermittently at a predetermined time interval.   The screen according to claim 5, wherein the predetermined time interval is random.   The screen according to claim 1, wherein the vibration applying unit is an ultrasonic vibrator.   The screen according to claim 1, wherein the vibration applying unit is an actuator that performs a reciprocating motion. A light source device for emitting light;
A light modulation device that modulates light emitted from the light source device in accordance with an image signal;
A projection device for projecting light modulated by the light modulation device;
A projector comprising: the screen according to claim 1, wherein an image emitted from the projection device is projected. A light source device for emitting light;
Scanning means for scanning the laser light emitted from the light source device;
An image display apparatus comprising: the screen according to claim 1, wherein light scanned by the scanning unit is projected.

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