JP2008151912A - 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 pair of substrates, and at least either of the pair of substrates has light transmissibility; and a vibration imparting means which is formed on at least either of the pair of substrates and vibrates the substrate. <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. 14, 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 a pair of substrates, and at least one of the pair of substrates has a light transmissive plate, and the pair of substrates. And a vibration applying means that vibrates the substrate and is formed on at least one of the substrates.

In the screen according to the present invention, the light scattering material in the medium can be moved (vibrated) by vibrating at least one of the pair of substrates by the vibration applying unit.
Thereby, since light is irradiated to the light diffusing material at various positions in the medium, the diffusion state of the light emitted from the light diffusing plate is temporally changed. Therefore, the speckle pattern of the light emitted from the light diffusing plate 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. Simple images can be displayed.
Further, since the vibration applying means can be built on the substrate, the entire screen can be easily assembled. 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.

In the screen of the present invention, it is preferable that the vibration applying means is a piezoelectric drive element.
In the screen according to the present invention, when a voltage is applied to the piezoelectric drive element, the piezoelectric drive element expands and contracts slightly. Due to the expansion and contraction of the piezoelectric drive element, the substrate in contact with the piezoelectric drive element vibrates. Therefore, it is possible to move (vibrate) the scattering material efficiently while being small in size by the piezoelectric drive element as the vibration applying means.

  The screen of the present invention includes a plurality of one-way electrodes extending in one direction on the substrate, and a plurality of other direction electrodes extending in another direction intersecting the one direction on the substrate, It is preferable that the piezoelectric driving element is provided at a position where the one-way electrode and the other-direction electrode intersect.

In the screen according to the present invention, the piezoelectric driving element disposed between the one-way electrode to which a voltage is applied and the other-direction electrode is driven, and the light scattering material in the medium moves. Thus, since the piezoelectric drive element is driven according to the one-way electrode and the other-direction electrode to which a voltage is applied, the light scattering material can be easily moved along a desired locus.
In particular, in a large screen, the light scattering material at the center of the screen is difficult to move, but by providing a one-way electrode and another-direction electrode so as to be positioned between pixels of the image projected on the screen. In particular, it is effective when the screen of the present invention is used for a transmission type screen. That is, since the vibration imparting means can be arranged on the entire screen without affecting the displayed image, the light scattering material at the center of the screen can also be moved reliably.

In the screen of the present invention, the material of the piezoelectric drive element is preferably lead zirconate titanate.
In the screen according to the present invention, since the piezoelectric driving element is lead zirconate titanate, a large distortion can be obtained with a small driving voltage, and thus the piezoelectric driving element has a large displacement. Thereby, since the voltage for driving the piezoelectric drive element can be small, it is possible to suppress power consumption.

  In the screen of the present invention, it is preferable that the vibration applying means generates a surface acoustic wave.

  In the screen according to the present invention, since the vibration applying means generates surface-acoustic-wave (SAW), the surface elastic wave has a straight traveling property, and therefore the entire substrate in contact with the vibration applying means is removed. Can be vibrated efficiently. Therefore, since the light scattering material in the medium can be reliably vibrated, scintillation can be suppressed more efficiently.

  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 unit is controlled by the control unit, and the light scattering material in the medium continuously moves along a circular orbit, an elliptic orbit, a random orbit, or a Brownian motion. In this way, by continuously moving (vibrating) 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.

  The screen according to the present invention is particularly preferably used for a transmission type screen. That is, in the case of a transmissive screen, light passes through the image forming area, so that the displayed image is not affected by providing the vibration applying means outside the image forming area. Therefore, a clear image can be displayed.

  In the screen of the present invention, it is preferable that the vibration applying means is provided at a position where light on the light diffusion plate is not projected.

  The screen according to the present invention is particularly preferably used for a transmission type screen. That is, in the case of a transmissive screen, since light passes through the image forming region, the displayed image is not affected by providing the vibration applying means at a position where the light is not projected. Therefore, a clear image can be displayed.

  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 capable of suppressing noise, vibration and the like and reducing scintillation is used, the image projected from the screen is displayed with a high quality image without luminance unevenness.

  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. It is 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 capable of suppressing noise, vibration, and the like and 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 the 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 disposed behind each of the laser light sources 31R, 31G, and 31B as a uniform illumination system for uniformizing the illuminance distribution of the laser light emitted from the laser light sources 31R, 31G, and 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 counter substrate 21 disposed on the incident side, a drive substrate 22 disposed on the emission side, and a dispersion medium 23. The counter substrate 21 and the drive substrate 22 are both light transmissive and are, for example, glass plates. The material of the counter substrate 21 and the drive substrate 22 is, for example, polycarbonate, cycloolefin resin, etc., in addition to being transparent, such as low hygroscopicity, heat resistance, low birefringence, and high dimensional stability. It is preferable to be composed of a material having properties.
A vibration supply unit 14 is provided on the surface of the drive substrate 22 opposite to the surface that contacts the dispersion medium 23.

Further, the dispersion medium 23 is sealed with a sealing material 24 provided along the peripheral edge between the counter substrate 21 and the drive substrate 22.
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 FIGS. 5 and 6, the vibration supply unit 14 includes an electrode unit 15, a piezoelectric driving element (vibration applying unit) 16, and a control unit (not shown) that controls a voltage applied to the electrode unit 15. I have. The piezoelectric drive element 16 is lead zirconate titanate (PZT).
The electrode unit 15 is provided in a matrix between pixels of an image projected on the screen 10 on the drive substrate 22. The electrode portion 15 includes a plurality of drive electrodes (one-way electrodes) 15a arranged in the vertical direction (one direction) of the screen 10 on the drive substrate 22 and a horizontal direction (the other direction) of the screen 10 orthogonal to the one direction. A plurality of common electrodes (other-direction electrodes) 15b are provided.
The drive electrode 15 a and the common electrode 15 b are provided at positions where the black matrix provided on the liquid crystal light valves 34 R, 34 G, and 34 B is projected onto the screen 10 when an image is projected onto the screen 10. That is, the positions of the drive electrode 15a and the common electrode 15b are aligned so as to match the position of the black matrix projected on the screen 10. Thus, since the drive electrode 15a and the common electrode 15b are provided at positions where no image is projected, the drive electrode 15a and the common electrode 15b do not adversely affect the image displayed on the screen 10.
Then, as shown in the enlarged view of the electrode portion 15 in FIG. 6, in the region sandwiched between the drive electrode 15a and the common electrode 15b where the drive electrode 15a and the common electrode 15b intersect, the piezoelectric drive that vibrates the diffusion plate 12 An element 16 is provided. Since the piezoelectric driving element 16 vibrates when a voltage is applied, the driving substrate 22 is vibrated through the driving electrode 15a in accordance with the vibration. The vibration of the drive substrate 22 is transmitted to the solvent 23a, and the particles 23b in the solvent 23a move (vibrate).

  The control unit always applies a voltage to the common electrode 15b, and controls the voltage value applied to the drive electrode 15a and the location of the drive electrode 15a to which the voltage is applied. Thereby, the control part can control each piezoelectric drive element 16 arrange | positioned in the some crossing position of the drive electrode 15a and the common electrode 15b separately.

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 (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.

  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 electrode unit 15 is controlled by the control unit, the piezoelectric driving element 16 vibrates, and accordingly, the driving substrate 22 vibrates. The vibration of the driving 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 piezoelectric driving element 16 is provided on the driving substrate 22, the particles 23 b move (vibrate) in conjunction with the vibration of the piezoelectric driving element 16. Therefore, since the light emitted from the diffusion plate 12 has its scattering state changed with time, the speckle pattern of the light emitted from the diffusion plate 12 is integrated by the afterimage effect to suppress scintillation. Become light. 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.
Furthermore, since the electrode unit 15 is provided in a matrix between pixels of the image projected on the screen 10 on the drive substrate 22, the screen 10 of the present embodiment is used as a transmissive screen. In this case, the light transmitted through the screen 10 is not affected, which is effective.
That is, the screen 10 and the rear projector 1 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 electrode unit 15 is provided on the driving substrate 22, but the electrode unit 15 may be provided on the counter substrate 21, and the electrode unit 15 may be provided on both the counter substrate 21 and the driving substrate 22. It may be.
Further, although the piezoelectric drive element 16 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.

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 reflection type screen, as shown in FIG. 7, 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 drive substrate 22 that contacts the dispersion medium 23, and the light incident on the screen is reflected. Therefore, since light does not transmit to the drive substrate 22 side, there is no need to provide the electrode portion 15 between the pixels. Therefore, even if the plurality of piezoelectric drive elements 16 are provided on the entire surface of the drive substrate 22. good. Thus, when used in a reflective screen, the degree of freedom in designing and arranging the electrode portion 15 increases.
Further, in the reflection type screen, the drive substrate 22 does not need to have light transmittance, and may have light shielding properties.

  In addition to the lead zirconate titanate (PZT), for example, quartz, lithium niobate, barium titanate, lead titanate, lead metaniobate, polyfluoride, etc. Various materials such as vinylidene, lead zinc niobate and lead scandium niobate are preferably used.

[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.
The screen 40 according to the present embodiment is different from the first embodiment in the configuration of the vibration supply unit 41.

As shown in FIG. 8, the vibration supply unit 41 includes a plurality of piezoelectric drive elements (vibration applying means) 42, a pair of electrodes 42a and 42b for applying a voltage to each piezoelectric drive element 42, and a pair of electrodes 42a and 42b. And a control unit 43 for controlling the voltage applied to the.
The plurality of piezoelectric drive elements 42 are sandwiched between a pair of electrodes 42a and 42b, respectively, and are provided on the drive substrate 22 outside the image display area (image forming area) A in which an image is displayed by the projection lens 37. ing. That is, a plurality of piezoelectric drive elements 42 are provided on each of the upper end surface 22a side and the lower end surface 22b side outside the image display area A along the peripheral edge on the drive substrate 22, and the right end surface 22c side and the left end surface 22d. Four are provided on the side.

Further, although there are a plurality of driving patterns of the plurality of piezoelectric driving elements 42 by the control unit 43, the relationship between the voltage applied to the pair of electrodes 42a and 42b as an example and time will be described with reference to the timing chart shown in FIG. To do.
First, as shown in FIG. 10, the plurality of piezoelectric driving elements 42 are divided and controlled by the control unit 43 into the right half and the left half of the screen 40. The piezoelectric drive elements 42 on the right half of the screen 40 are L1, L2, L3... L8, L9, L10 in the clockwise direction from the central portion on the upper end surface 22a side. Similarly, the piezoelectric drive element 42 on the left half of the screen 40 is M1, M2, M3... M8, M9, M10 in the counterclockwise order from the central portion on the upper end surface 22a side.

The relationship between the voltage applied to each piezoelectric drive element L1, L2, L3... L8, L9, L10, M1, M2, M3... M8, M9, M10 and time is as shown in FIG. On the half side, voltages are applied to the piezoelectric drive elements 42 that are adjacent clockwise in order from the piezoelectric drive elements L1, L5, and L9 with a predetermined time interval. In addition, after a voltage is applied to the piezoelectric drive element L10, a voltage is applied to the piezoelectric drive element L1.
Similarly, voltages are applied to the left half side piezoelectric driving elements M1 to M10 in the counterclockwise order from the piezoelectric driving elements M1, M5, and M9.
As a result, as shown in FIG. 10, the solvent 23a of the diffusion plate 12 of the screen 40 causes convection clockwise in the right half and counterclockwise convection in the left half. This convection causes the particles 23b to move continuously along a circular orbit.

  In the screen 40 according to the present embodiment, the same effect as that of the screen 10 of the first embodiment can be obtained. Further, in the screen 40 of the present embodiment, the plurality of piezoelectric driving elements 42 are controlled by the control unit 43, and the particles 23b move (vibrate) continuously along a circular orbit, so that the particles 23b move to the dead point (movement). Does not have a point that stops even for a moment). Accordingly, since there is no moment of interference even for a moment, it is possible to continuously maintain the effect of suppressing flicker (flickering of the image on the screen) speckle. Further, since the piezoelectric drive element 42 is provided outside the image display area A, it can be applied to a reflection type screen, but is effective particularly when used for a transmission type screen. That is, in the case of a transmissive screen, since light passes through the image display area A, disposing the piezoelectric drive element 42 outside the image display area A does not adversely affect the displayed image. Therefore, a clear image can be displayed.

In addition to the circular orbit described above, the particles 23b can be continuously moved along an elliptical or random or Brownian motion by controlling the plurality of piezoelectric driving elements 42 by the control unit 43. Further, as shown in FIG. 11, convection of three or more circular orbits (eight in the illustrated example) can be generated. That is, it is possible to move the particles 23b in a complicated manner by providing 20 or more piezoelectric drive elements 42 as shown in the above embodiment.
Moreover, although the piezoelectric drive element 42 is provided along the outer peripheral end face side on the drive substrate 22 of the diffusion plate 12, at least one of the upper end face 22a side, the lower end face 22b side, the right end face 22c side, and the left end face 22d side. The structure provided in the one end surface may be sufficient. Furthermore, a plurality of piezoelectric drive elements 42 may be provided instead of a single one. However, when the particles 23b are vibrated so as to have a more complicated movement, it is preferable to provide a plurality of piezoelectric drive elements 42.
Further, the piezoelectric drive element 42 may be arranged so that vibration is applied in an oblique direction with respect to the end face of the drive substrate 22. Thereby, it becomes easy to produce a circular orbit in the particle 23b in the solvent 23a.
Similarly, in the first embodiment, the electrode unit 15 may be controlled so that the particles 23b move along a circular orbit.

[Third Embodiment]
Next, a third embodiment according to the present invention will be described with reference to FIG.
The screen 50 according to the present embodiment is different from the first embodiment in the configuration of the vibration supply unit 51.

As shown in FIG. 12, the vibration supply unit 51 controls the surface acoustic wave element having the piezoelectric substrate 52 and the electrode portion 53 formed on one surface 52 a of the piezoelectric substrate 52, and the voltage applied to the electrode portion 53. Part 54.
The piezoelectric substrate 52 is provided on the upper end surface 22a side of the drive substrate 22 outside the image display area (image forming area) A. The electrode unit 53 includes a comb-shaped first IDT (Inter-Digital Transducer) electrode 53a and a second IDT electrode 53b, and the first IDT electrode 53a and the second IDT electrode 53b are arranged to mesh with each other. ing. Further, the electrode unit 53 is provided with a high-frequency signal source 53c connected to the first IDT electrode 53a and the second IDT electrode 53b.
Examples of the material of the piezoelectric substrate 52 include quartz, lithium tantalate (LiTaO ₃ ), lithium niobate (LiNbO ₃ ), and lithium tetraborate (Li ₂ B ₄ O ₇ ).

The drive of the vibration supply part 51 is demonstrated.
First, when a high-frequency signal is output from the high-frequency signal source 53c, the high-frequency signal is applied to the first and second IDT electrodes 53a and 53b, and a surface-acoustic-wave (SAW) W is applied on the piezoelectric substrate 52. Occurs. The surface acoustic wave W is propagated to the drive substrate 22 provided in contact with the piezoelectric substrate 52. Thereby, since the solvent 23a of the diffusion plate 12 of the screen 50 vibrates, the particles 23b in the solvent 23a move (vibrate).

In the screen 50 according to the present embodiment, the same effect as that of the screen 10 of the first embodiment can be obtained. Further, in the screen 50 of the present embodiment, since the surface acoustic wave W has a straight traveling property by generating the surface acoustic wave W from the vibration supply unit 51, the drive substrate 22 that is in contact with the piezoelectric substrate 52 is entirely disposed. Can be vibrated efficiently. Further, the frequency of the surface acoustic wave W to be propagated can be selected by changing the width and interval of the first and second IDT electrodes 53a and 53b. Therefore, by designing the first and second IDT electrodes 53a and 53b so that the vibration of the particles 23b is in a desired state, it is possible to reliably suppress the scintillation of light emitted from the screen 50. Moreover, since the piezoelectric substrate 52 is provided outside the image display area A as in the second embodiment, this embodiment is also preferably used for a transmission type screen.
Although one piezoelectric substrate is provided on the upper end surface 22a of the drive substrate 22, it may be arranged at a plurality of locations outside the image display area A as in the second embodiment.
Further, when used for a reflective screen, the vibration supply unit 51 may be provided in the image display area A.

[Fourth Embodiment]
Next, a fourth 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. 13, 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.

In the image display device according to the present invention, the screen 10 with reduced scintillation while suppressing noise, vibration, and the like is used, so that 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.
In the present embodiment, the screen 10 of the first embodiment has been described. However, the screen 40 of the second embodiment or the screen 50 of the third 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.
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.
In addition, 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. In order to prevent the particles from further sedimentation, a plurality of regions sandwiched between the substrate and the drive substrate are provided. It may be divided into 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 principal part sectional drawing which shows the detail of the screen of the projector of FIG. It is an expanded sectional view which shows 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 screen of the projector which concerns on 2nd Embodiment of this invention. It is a timing chart which shows the drive timing of the vibration provision means which concerns on 2nd Embodiment of this invention. It is a top view which shows the flow of the solvent of the screen of the projector of FIG. It is a schematic block diagram which shows the modification of the screen of the projector which concerns on 2nd Embodiment of this invention. It is a schematic block diagram of the screen of the projector which concerns on 3rd Embodiment of this invention. It is a schematic block diagram of the image display apparatus which concerns on 4th 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), 15a ... Drive electrode (unidirectional electrode), 15b ... Common Electrodes (other-direction electrodes), 16, 42 ... piezoelectric drive elements (vibration applying means), 21 ... counter substrate (substrate), 22 ... drive substrate (substrate), 23a ... solvent (medium), 23b ... particles (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), 43, 54: Control unit, 100: Image display Device 101 ... Light source device

Claims (10)

A movable light scattering material is dispersed in a medium provided between a pair of substrates, and at least one of the pair of substrates has a light transmissive plate,
A screen, comprising: a vibration applying unit that is formed on at least one of the pair of substrates and vibrates the substrate.   The screen according to claim 1, wherein the vibration applying unit is a piezoelectric drive element. A plurality of unidirectional electrodes extending in one direction on the substrate;
A plurality of other direction electrodes extending in the other direction intersecting the one direction on the substrate,
The screen according to claim 2, wherein the piezoelectric driving element is provided at a position where the one-way electrode and the other-direction electrode intersect.   4. The screen according to claim 2, wherein the material of the piezoelectric driving element is lead zirconate titanate.   The screen according to claim 1, wherein the vibration applying unit is a surface elastic element.   The screen according to claim 1, further comprising a control unit that controls the vibration applying unit such 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 6, wherein the vibration imparting unit is provided at a position where light on the light diffusion plate is not projected. 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.

Images