WO2015045970A1 - Image display system, and reflective screen - Google Patents

Abstract

Disclosed is an image display system that is provided with: a projector using a laser as a light source; and a reflective screen that projects an image projected from the projector. The reflective screen has: a semi-transmissive layer wherein particles are dispersed in a transparent material that is transparent with respect to visible light, said particles having a refractive index different from that of the transparent material; and a reflecting layer on a semi-transmissive layer surface on the side opposite to the projector, said reflecting layer reflecting visible light.

Description

Image display system and reflective screen

The present invention relates to an image display system for projecting an image from a projector using a laser as a light source onto a reflective screen, and a reflective screen.

Conventionally, an image display system having a projector using a laser as a light source and a reflective screen for projecting an image from the projector is known. However, when a laser is used as the light source of the projector, the laser light is highly coherent, so the light scattered by the screen interferes and the pattern of random bright and dark spots (speckle noise) on the screen. May occur. Such speckle noise looks glaring with the naked eye, which may cause discomfort to the observer.

As a method of reducing such speckle noise, a method of making the speckle noise less visible by vibrating the screen and averaging the pattern has been known (for example, see Patent Document 1).

JP 2008-191533 A

However, the method as disclosed in Patent Document 1 has a problem that a power source such as a motor is required to cause vibration on the screen, resulting in an increase in power consumption of the entire system. In addition, a configuration having a drive unit such as a motor has a problem that the possibility of failure is high, a problem that noise is generated by vibration, and an uncomfortable feeling is given to an image viewer.

The present invention has been made in view of the above-described problems, and an object thereof is to easily reduce speckle noise without making the apparatus large.

An image display system of the present invention is an image display system comprising a projector using a laser as a light source, and a reflective screen for projecting an image from the projector,
The reflective screen has a transparent material transparent to visible light, a transflective layer in which particles having a refractive index different from that of the transparent material are dispersed, and a surface of the transflective layer opposite to the projector, And a reflective layer that reflects visible light.

According to the above configuration, the reflective screen has a translucent layer in which particles having a refractive index different from that of the transparent material are dispersed in a transparent material transparent to visible light, and is opposite to a projector having the transflective layer. And a reflective layer that reflects visible light. Accordingly, the laser light emitted from the projector is sequentially diffused in the process of passing through the inside of the semi-transmissive layer, and reflected to the viewer side by the reflective layer. As a result, the angle multiplicity of the laser beam is increased, and speckle can be reduced.
Thus, according to the above configuration, the speckle noise can be easily reduced without increasing the size of the device because the speckle is reduced by providing the transflective layer on the reflective screen. Become.

In the configuration of the present invention described above, the particles are MgO, CaO, CaCO ₃ , SrO, SrCO ₃ , BaO, BaCO ₃ , Al ₂ O ₃ , Sc ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , ZrO, ZnO. , B ₂ O ₃ , Al ₂ O ₃ , SiO ₂ , SnO, and PbO are preferably at least one kind. When the particles are at least one kind of the group, speckles can be more suitably reduced.

The reflective screen of the present invention is a reflective screen for projecting an image from a projector using a laser as a light source,
A translucent layer in which particles having a refractive index different from that of the transparent material are dispersed in a transparent material transparent to visible light;
And a reflective layer that reflects visible light.

According to the above configuration, the reflective screen has a translucent layer in which particles having a refractive index different from that of the transparent material are dispersed in a transparent material transparent to visible light, and is opposite to a projector having the transflective layer. And a reflective layer that reflects visible light. Accordingly, the laser light emitted from the projector is sequentially diffused in the process of passing through the inside of the semi-transmissive layer, and reflected to the viewer side by the reflective layer. As a result, the angle multiplicity of the laser beam is increased, and speckle can be reduced.
Thus, according to the above configuration, the speckle noise can be easily reduced without increasing the size of the device because the speckle is reduced by providing the transflective layer on the reflective screen. Become.

In the configuration of the present invention described above, the particles are MgO, CaO, CaCO ₃ , SrO, SrCO ₃ , BaO, BaCO ₃ , Al ₂ O ₃ , Sc ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , ZrO, ZnO. , B ₂ O ₃ , Al ₂ O ₃ , SiO ₂ , SnO, and PbO are preferably at least one kind. When the particles are at least one kind of the group, speckles can be more suitably reduced.

According to the image display system and the reflective screen of the present invention, it is possible to easily reduce speckle noise without making the apparatus large.

It is side surface sectional drawing which shows the reflection type screen which concerns on this embodiment typically. 1 is a schematic diagram of an image display system according to the present embodiment. It is the schematic of the projection system used in the effect verification experiment. It is the schematic of the speckle measurement system used in the effect verification experiment.

An image display system and a reflective screen according to an embodiment of the present invention will be described with reference to the drawings. In each figure, the dimensional ratio in the drawing does not necessarily match the actual dimensional ratio.

In the following, first, the reflective screen will be described. FIG. 1 is a side sectional view schematically showing a reflective screen according to the present embodiment.

As shown in FIG. 1, the reflective screen 10 has a configuration in which a reflective layer 12 and a semi-transmissive layer 14 are laminated. In the reflective screen 10, laser light is irradiated from the semi-transmissive layer 14 side (left side in FIG. 1), and the light is sequentially diffused in the process of passing through the semi-transmissive layer 14. Is reflected. In the present embodiment, the case where the reflective layer 12 and the semi-transmissive layer 14 are laminated without interposing another layer will be described. However, the other layer is not deviated from the scope of the present invention. It may be interposed between them.

The reflective screen 10 is preferably one that can be wound into a roll from the viewpoint of storage, transportation, and the like. From such a viewpoint, each member constituting the reflective screen 10 is preferably formed of a material having some degree of flexibility.

The reflection layer 12 is a layer that reflects the laser light from the projector and reflects the image light so that the observer on the projector side can observe it as an image. As the reflective layer 12, the same material as that used in a conventionally known reflective screen can be used. Specifically, for example, a mat-finished fabric coated with a white paint or the like, and a mat-finished resin sheet can be used. Other specific examples include a metal layer formed by vapor deposition or the like, or a layer made of a reflective paint sprayed by spray coating.

In the semi-transmissive layer 14, particles having a refractive index different from that of the transparent material are dispersed in a transparent material transparent to visible light. In the present specification, “transparent to visible light” means that when the transparent material is formed into a film having a film thickness of 1 mm, the light transmittance is 70 in all wavelength ranges within a wavelength range of 400 to 760 nm. % Or more. The light transmittance is a ratio of the intensity before transmitting the film for measurement and the intensity after transmitting the film for measurement, and is obtained by the following formula.
Light transmittance = [(Intensity after transmission) / (Intensity before transmission)] × 100 (%)

Specific examples of the transparent material include polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, ABS resin, acrylic resin, polycarbonate, acrylonitrile, epoxy resin, unsaturated polyester resin, polyimide resin, silicone resin, diallyl phthalate resin, Examples include polyurethane resins, ultraviolet curable urethane acrylate resins, ultraviolet curable epoxy acrylate resins, and ultraviolet curable polyester acrylate resins. Of these, polyvinyl chloride is preferred from the viewpoints of durability, ease of processing, and ease of dispersion of the particles.

The particle is not particularly limited as long as it has a refractive index different from that of the transparent material. This is because laser light can be scattered if the refractive index is different from that of the transparent material.

Examples of the particles include MgO, CaO, CaCO ₃ , SrO, SrCO ₃ , BaO, BaCO ₃ , Al ₂ O ₃ , Sc ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , ZrO, ZnO, B ₂ O ₃ , Al. _{2 O 3, SiO 2, SnO} , and is preferably at least one or more consisting of the group of PbO. When the particles are at least one kind of the group, speckles can be more suitably reduced. Among these, TiO ₂ and Al ₂ O ₃ are preferable from the viewpoint of whiteness and durability.

The addition amount of the particles is preferably 0.3 to 5% by volume when the transparent material is 100% by volume. When the amount of the particles added is 0.3 to 5% by volume when the transparent material is 100% by volume, a speckle suppression effect can be suitably obtained.

The average particle size of the particles is preferably in the range of 500 nm to 30 μm, and more preferably in the range of 1 μm to 25 μm. By setting the average particle size of the particles to 500 nm or more, aggregation of particles can be suppressed and handling can be facilitated. In addition, by setting the average particle size of the particles to 30 μm or less, it is possible to suppress wear of the apparatus in the process of handling the particles and to reduce unintended impurity contamination.

The maximum particle size of the particles is preferably 50 μm or less, and more preferably 40 μm or less. By setting the maximum particle size to 50 μm or less, it can be made difficult to visually recognize with the naked eye, and deterioration of image quality can be suppressed.
The minimum particle size of the particles is preferably 100 nm or more, and more preferably 250 nm or more. By setting the minimum particle diameter to 100 nm or more, it is possible to suppress the occurrence of Rayleigh scattering in which the scattering characteristics easily change depending on the wavelength.

The thickness of the semi-transmissive layer 14 is preferably in the range of 0.1 to 3 mm, and more preferably in the range of 0.2 to 1 mm. By setting the thickness of the semi-transmissive layer 14 to 0.1 mm or more, an effect of suppressing speckles can be suitably obtained. In addition, by setting the thickness of the semi-transmissive layer 14 to 3 mm or less, a certain degree of strength can be ensured and the handleability is excellent.

In the semipermeable membrane layer 14, the relationship between the intensity Iin of light traveling in the layer in the vertical direction from the surface and the position d in the depth direction from the surface preferably satisfies the following formula (1).
<Formula (1)>
log (Iin) = ad + b (a and b are constants)

The fact that the semipermeable membrane layer 14 satisfies the above formula (1) means that when the depth from the surface is, for example, d1, d2, d3..., The surfaces of the depths d1, d2, d3. (For example, 20% of the laser light reaching the surface of depth d1 is diffused, 20% of the laser light reaching the surface of depth d2 is diffused, and depth d3) This means that 20% of the laser light reaching the surface is diffused). Therefore, when the semipermeable membrane layer 14 satisfies the above formula (1), the angle multiplicity of the laser beam becomes larger, and speckle can be further reduced. Examples of the method for producing the semipermeable membrane layer 14 so that the semipermeable membrane layer 14 satisfies the above formula (1) include a method of uniformly dispersing the particles in the transparent material. In addition, as another manufacturing method, for example, a method of dispersing the transparent material with a gradation so that particles having a large particle size among the particles have a small number density and particles having a small particle size to have a large number density may be mentioned. be able to.

As a method for manufacturing the reflective screen 10, first, the semipermeable membrane layer 14 is manufactured. A method for producing the semipermeable membrane layer 14 is not particularly limited, and examples thereof include a method in which the particles are dispersed in the transparent material, and the obtained dispersion is applied in a sheet form. As a method of dispersing the particles in the transparent material, various kinds of mixers such as a dissolver and a homogenizer, a kneader, a roll, a bead mill, a self-revolving stirrer and the like can be used. Further, when dispersing, a solvent may be used, and after coating in a sheet form, it may be dried.

Next, a conventionally known screen having the reflective layer 12 is prepared, and the semipermeable membrane layer 14 is bonded onto the reflective layer 12. Bonding can be performed by pressure bonding. At this time, pressure bonding may be performed while heating (for example, 30 to 150 ° C.).

The reflective screen 10 has been described above.

Next, the image display system according to this embodiment will be described. FIG. 2 is a schematic diagram of the image display system according to the present embodiment.

As shown in FIG. 2, the image display system 50 includes a projector 20 and a reflective screen 10.

In the present invention, a projector using a laser as a light source is adopted as the projector. As a projector using a laser as a light source, a conventionally known projector can be employed.

The projector 20 according to the present embodiment includes a laser light source 50 including a red laser light source 50R, a green laser light source 50G, and a blue laser light source 50B, a dichroic mirror 52, a lens 54, a rod integrator 56, and a lens 58. , A mirror 60, a light modulation element 62, and a projection lens 64.

In the projector 20, first, the laser light emitted from the red laser light source 50R, the green laser light source 50G, and the blue laser light source 50B is synthesized by the dichroic mirror 52. Next, the light synthesized by the dichroic mirror 52 is collected by the lens 54 and is incident on the rod integrator 56. In the rod integrator 56, the light intensity distribution is made uniform. Thereafter, an image of the end surface of the rod integrator 56 is formed on the reflection type light modulation element 62 using the lens 58 and the mirror 60, and the image formed by the light modulation element 62 is reflected by the projection lens 64. Projected on top.

As described above, the reflective screen 10 includes a translucent layer 14 in which particles having a refractive index different from that of the transparent material are dispersed in a transparent material transparent to visible light, and the projector 20 of the transflective layer 14. A reflective layer 12 that reflects visible light is provided on the opposite surface side. Therefore, the laser light emitted from the projector 20 is sequentially diffused in the process of passing through the semi-transmissive layer 14 and reflected by the reflective layer 12 toward the viewer (projector 20 side). As a result, the angle multiplicity of the laser beam is increased, and speckle can be reduced.
As described above, according to the reflective screen 10 and the image display system 50, the reflective screen 10 is provided with the semi-transmissive layer 14 to reduce speckles. In addition, speckle noise can be reduced.

In the above-described embodiment, the case where the laser light source included in the projector is three colors of red, green, and blue has been described. However, in the present invention, the projector only needs to have at least one laser light source, The number may be different. The optical system is not limited to that shown in FIG. 2, and the number and position of mirrors and lenses may be different. In the above-described embodiment, the case where the rod integrator 56 is used as a means for making the light uniform has been described, but a fly-eye lens may be used. Further, in the above-described embodiment, the case where the reflection type element is used as the light modulation element has been described, but a transmission type element may be used.

Next, the verification experiment of the speckle suppression effect will be described. FIG. 3 is a schematic diagram of the projection system used in the effect verification experiment.

Example 1
In the verification experiment of the speckle suppression effect, as shown in FIG. 3, the laser light emitted from the laser light source 70 enters the optical fiber 72, and the hexagonal prism integrator 74 attached to the output end of the optical fiber 72. The light intensity distribution was made uniform. An image of the end face of the rod integrator 74 was projected on the screen 80 at a magnification of about 100 times using the lens 76 and the lens 78. The characteristics of each member used for the projection experiment on the screen 80 are as follows.
Laser light source 70: center wavelength 532 nm, half-value width 0.2 nm, beam intensity: 2 W
Optical fiber 72: Core diameter 0.8 mm, length 2 m, NA = 0.39
Rod integrator 74: hexagonal prism shape, opposite side dimension 2 mm, length 50 mm
Lens 76 (rod integrator side): Focal length 7.9 mm, installed at 7.9 mm from rod integrator Lens 78 (screen side): Focal length 750 mm, installed at 750 mm from screen

The screen 80 was prepared as follows. First, a semipermeable membrane layer was manufactured. The semipermeable membrane layer is produced by preparing a raw material in which Al ₂ O ₃ particles and TiO ₂ particles are sufficiently mixed with a vinyl chloride resin, then heating and melting at 200 ° C., and extruding the softened material from the slit. It processed into the sheet | seat shape of thickness 0.5mm.
The additive amount of Al ₂ O ₃ particles was 4% by weight with respect to the entire semipermeable membrane layer, and the additive amount of TiO ₂ particles was 1% by weight with respect to the entire semipermeable membrane layer.
Further, the particle diameter of the added Al ₂ O ₃ particles and the particle diameter of the TiO ₂ particles are as follows.
Al ₂ O ₃ : average particle size: 8 μm, minimum particle size of 0.2 μm, maximum of 20 μm
TiO ₂ : Average particle size: 8 μm, minimum particle size of 0.2 μm, maximum of 20 μm

The linear transmittance of the manufactured semi-transmissive layer was 40%. Here, the linear transmittance means the ratio of the intensity of light transmitted in the direction perpendicular to the screen to the intensity of light incident in the direction perpendicular to the screen. Linear transmission decreases as the angle of the light beam changes due to scattering. When the linear transmittance is too low, most of the light is scattered only on the surface of the semi-transmissive layer, the effect of multiplexing is reduced, and the effect of reducing speckle is reduced. If the linear transmittance is too high, most of the light rays are reflected by the reflective layer on the back surface, so that the effect of angle multiplexing is reduced and the speckle reduction effect is reduced. In Example 1, since the linear transmittance is 40%, it is suitable as a condition for obtaining a speckle reduction effect. In the present invention, the linear transmittance of the semi-transmissive layer is preferably in the range of 20 to 60%.

Next, product name: Stagelite Matt White 100 (corresponding to the reflective layer of the present invention) manufactured by Harkness Screen was prepared, and the semipermeable membrane layer produced on the reflective layer was bonded. Bonding was performed by pressure bonding at 60 ° C.

FIG. 4 is a schematic diagram of the speckle measurement system used in the effect verification experiment. As shown in FIG. 4, the image projected on the screen 80 was taken by the CCD camera 82 from a direction of 15 degrees with respect to the direction in which the screen 80 is viewed vertically. An aperture 86 having a diameter of 1 mm was installed in front of the camera lens 84. The distance between the CCD camera 82 and the screen 80 was 700 mm. The CCD camera 82 was controlled by a measurement computer 88. An average value A and a standard deviation σ of the signal intensity in the photographed photographing surface were obtained, and speckle contrast σ / A was calculated. As a result, the speckle contrast was 9.9%.

(Comparative Example 1)
Speckle contrast σ / A is calculated in the same manner as in Example 1 except that a semi-transmissive layer is not bonded to a product name: Stagelite Matte White 100 (corresponding to the reflective layer of the present invention) manufactured by Harkness Screen. did. As a result, the speckle contrast was 18.0%.

(result)
The comparison between Example 1 and Comparative Example 1 confirmed the speckle suppression effect due to the use of the semi-transmissive layer.

As mentioned above, although the embodiment of the present invention has been described, the present invention is not limited to the above-described example, and it is possible to make design changes as appropriate within a range that satisfies the configuration of the present invention.

DESCRIPTION OF SYMBOLS 10 Reflective screen 12 Reflective layer 14 Transflective layer 20 Projector 50 Image display system

Claims (4)

1. An image display system comprising a projector using a laser as a light source, and a reflective screen for projecting an image from the projector,
   The reflective screen has a transparent material transparent to visible light, a transflective layer in which particles having a refractive index different from that of the transparent material are dispersed, and a surface of the transflective layer opposite to the projector, An image display system comprising: a reflective layer that reflects visible light.
2. The particles are MgO, CaO, CaCO ₃ , SrO, SrCO ₃ , BaO, BaCO ₃ , Al ₂ O ₃ , Sc ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , ZrO, ZnO, B ₂ O ₃ , Al _2. The image display system according to claim 1, wherein the image display system is at least one kind of a group consisting of O ₃ , SiO ₂ , SnO, and PbO.
3. A reflective screen that projects images from a projector using a laser as a light source,
   A translucent layer in which particles having a refractive index different from that of the transparent material are dispersed in a transparent material transparent to visible light;
   A reflective screen comprising a reflective layer that reflects visible light.
4. The particles are MgO, CaO, CaCO ₃ , SrO, SrCO ₃ , BaO, BaCO ₃ , Al ₂ O ₃ , Sc ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , ZrO, ZnO, B ₂ O ₃ , Al _2. The reflective screen according to claim 3, wherein the reflective screen is at least one kind of a group consisting of O ₃ , SiO ₂ , SnO, and PbO.

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