JP2007140112A - Transmission type screen and projection type display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission type screen and a projection type display which are capable of reducing scintillation, while excellently keeping resolution and brightness. <P>SOLUTION: The transmission type screen 20 comprises a Fresnel lens sheet 30 for making projected light into approximately parallel light and a lenticular lens sheet 40 on which a BS layer 45 shielded from light other than the focused component of a cylindrical lens 43 is provided. A third diffusion layer 33 is provided on the Fresnel lens sheet 30 and a first diffusion layer 49 and a second diffusion layer 48 are provided on the lenticular lens sheet 40. The diffusion level of the first diffusion layer 49 is higher than those of the other diffusion layers of the lenticular lens sheet 40 and the third diffusion layer 33 and the refractive index difference between a light diffusion material and a light diffusion substrate in each diffusion layer of the lenticular lens sheet 40 is smaller than that of the third diffusion layer 33 of the Fresnel lens sheet 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmissive screen and a projection display.

Conventionally, a rear projection television is known as a projection display provided with a transmissive screen. In recent years, MD-type projection televisions have emerged as opposed to thin large-sized displays such as liquid crystal displays (LCDs) and plasma displays (PDPs). An MD projection television, for example, projects projection light modulated using a display device such as an LCD, LCOS (LCD on Silicon; a type of reflective liquid crystal panel), or a digital micromirror device (DMD) from the rear side of the transmissive screen. Projected.
This MD projection television can easily be increased in size to 40 inches or more, has a good image quality because of digital display, and can be manufactured at a relatively low cost. Has been.
On the other hand, MD-type projection television display devices have recently been remarkably miniaturized, for example, 0.7 inch size, and the projection magnification has been increased to project onto a large screen of 40 inches or more, for example. is doing.
For this reason, the pupil diameter of the projection lens of the display device is reduced, and so-called scintillation is becoming more conspicuous. Scintillation is a phenomenon in which minute spot-like high-intensity light that is not included in the projected image is observed from the viewpoint of the observer, and flickering or a glare-like glare image can be seen.

A transmissive screen used for such a projection display as an MD projection television is composed of a Fresnel lens sheet that adjusts the direction of incident light and emits it as substantially parallel light, and a Fresnel lens sheet to provide an appropriate viewing angle. Lenticular lens sheet that diffuses the emitted light from, for example, a cylindrical lens group arranged in the horizontal and vertical directions (not limited to the configuration in which the cylindrical lens groups are arranged in one direction, but the cylindrical lens groups are arranged in a plurality of directions) And various types of light diffusing lens array sheets, such as a structure in which unit lenses are two-dimensionally arranged.
A diffusion layer for diffusing transmitted light is provided in the Fresnel lens sheet and the lenticular lens sheet in order to reduce luminance unevenness and scintillation.
For example, Patent Document 1 has at least two diffusion portions separated in the light transmission direction in a transmission type screen including a lens sheet or an optical sheet having an optical function such as light collection or diffusion. The diffusion part close to the light source side has first diffusible fine particles added to the first base material, and the diffusion part close to the observation side has second diffusible fine particles added to the second base material. And the difference in refractive index between the first base material and the second base material are smaller than those between the second diffusible fine particles and the second base material.
According to the description of Patent Literature 1, since the light source light is diffused so that the diffusing part eliminates the coherence of the light source light, problems such as scintillation and speckle can be solved. Also, by disposing a plurality of diffusion layers apart in the light transmission direction, it is possible to improve the scintillation while reducing the diffusion degree of each diffusion layer, so that the resolution is reduced and the brightness of the image is reduced. It is said that scintillation can be improved in a state where the decrease is suppressed.
Further, in Patent Document 2, in a transmissive screen including a lens sheet or an optical sheet having an optical function such as condensing or diffusing light, a diffusing portion of the lens sheet or the optical sheet positioned on the light source side is observed. The light diffusion degree of the lens sheet or the optical sheet located on the side is smaller than that of the diffusion part. And the Example common to patent document 1 is described in the refractive index difference of a diffusible fine particle and a base material.
In Patent Document 3, in a light diffusion substrate having a light diffusion layer in which a light diffusion material is dispersed and mixed in a resin, the concentration of the light diffusion material dispersed is different in two or more layers in the thickness direction. A transmissive screen is described. The concentration of the light diffusing material between each layer is described as having both a high concentration and a low concentration on the observation side as compared to the light source side, but it is preferable to make the dispersion concentration on the observation side low. ing.
Japanese Patent No. 3465906 (FIGS. 2 and 8) Japanese Patent No. 3606862 (FIGS. 2 and 8) JP 2002-236319 A (FIGS. 1 and 3)

However, the conventional transmissive screen as described above and the projection display using them have the following problems.
In the techniques described in Patent Documents 1 and 2, since a plurality of diffusion layers are provided and disposed at a plurality of locations along the light transmission direction, the resolution, brightness degradation, scintillation, and the like are in a trade-off relationship. Although it is easy to balance the improvement, there is a problem that scintillation may not be sufficiently improved because the setting of the magnitude relationship between the refractive index difference between the diffusible fine particles of the diffusion layer and the substrate is inappropriate.
In these technologies, the difference in refractive index between the diffusible fine particles and the substrate in the diffusion layer close to the light source side is made smaller than the difference in refractive index between the diffusible fine particles and the substrate in the diffusion layer close to the observation side. The refractive index difference and the degree of diffusion increase in the direction from the observation side to the observation side. Therefore, since light is gradually diffused, it is substantially equivalent to the case where the arrangement interval of each diffusion layer is short. As a result, the efficiency of the scintillation reducing action obtained by separating the plurality of diffusion layers in the light transmission direction is deteriorated.
In the technique described in Patent Document 3, since the light diffusing material is provided with two or more different light diffusing layers, the degree of light diffusion in each layer is variable, and scintillation is reduced as a whole. However, since only the concentration at which the light diffusing material is dispersed is changed, there is a problem that it is difficult to balance the trade-off relationship between reduction in resolution and brightness and reduction in scintillation.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a transmission screen and a projection display capable of reducing scintillation while maintaining good resolution and brightness. .

In order to solve the above-described problems, in the invention described in claim 1, the Fresnel lens sheet that makes the projection light projected from the light source substantially parallel light, and the projection light that is made substantially parallel light by the Fresnel lens sheet A light diffusing lens array sheet in which a plurality of diverging lenses are arranged and a light shielding layer is provided in the vicinity of the plurality of lenses, and a light diffusing material is applied to the Fresnel lens sheet and the light diffusing lens array sheet. A transmission type screen provided with a diffusion layer dispersed in a diffusion substrate, wherein the diffusion layer of the light diffusion lens array sheet is the first diffusion layer located closest to the observation side and the light diffusion lens array sheet The light diffusion lens array sheet includes a plurality of diffusion layers including at least a second diffusion layer provided closest to the light shielding layer, and the degree of diffusion of the first diffusion layer is the light diffusion lens array sheet. It is larger than any of the other diffusion layers and the diffusion layer of the Fresnel lens sheet, and the difference in refractive index between the light diffusion material and the light diffusion base material in each diffusion layer of the light diffusion lens array sheet is The diffusion layer of the Fresnel lens sheet has a smaller structure than the refractive index difference between the light diffusing material and the light diffusing substrate.
According to the present invention, the projection light projected from the light source is transmitted through the Fresnel lens sheet and is made to be substantially parallel light while being diffused by the diffusion layer provided on the Fresnel lens sheet. And the projection light made into the substantially parallel light permeate | transmits a light-diffusion lens array sheet | seat, is condensed by the some lens provided in the light-diffusion lens array sheet | seat, and is diverge | evaporated. The projection light is diffused by a plurality of diffusion layers including the second diffusion layer and the first diffusion layer provided on the light diffusion lens array sheet until the projection light is emitted from the light diffusion lens array sheet, and a viewing angle is obtained. Is transmitted as transmitted light.
Since the diffusion degree of the first diffusion layer located closest to the observation side is greater than the diffusion degree of any of the other diffusion layers and the Fresnel lens sheet of the light diffusion lens array sheet, The degree of diffusion is reduced. That is, the non-parallel light component of the Fresnel lens sheet is reduced, and the component condensed by the plurality of lenses of the light diffusion lens array sheet is increased. For this reason, the components removed by the light shielding layer are reduced, the light use efficiency is improved, and the deterioration of brightness is suppressed.
And a scintillation can be reduced by comprising the pair of the diffusion layer spaced apart in the light transmission direction between the first diffusion layer and the diffusion layer of the Fresnel lens sheet.
At that time, in the diffusion layer of the light diffusion lens array sheet having a relatively large diffusion degree, the refractive index difference between the light diffusing material and the light diffusing substrate (hereinafter, unless otherwise specified, simply the refractive index difference). Abbreviated to be relatively small), the dispersion concentration of the light diffusing material in the diffusing layer of the light diffusing lens array sheet is relatively increased, and the light diffusing material does not pass through the light diffusing material and travels straight through the light diffusing substrate. The component of light that exits with high brightness is reduced. Therefore, it is possible to suppress luminance unevenness that leads to glare peculiar to scintillation.
Further, in the light diffusion lens array sheet, since the second diffusion layer is provided in the vicinity of the opening adjacent to the light shielding layer where the projection light is once condensed, the projection light is diffused in the vicinity of the focal position by the plurality of lenses. The Therefore, compared with the case where it diffuses only by the 1st diffused layer, or the case where it diffuses only in the position away from the light shielding layer, the blur of an image can be reduced and favorable resolution can be obtained.
The degree of diffusion can be expressed by, for example, a haze value (unit,%).

According to a second aspect of the present invention, in the transmissive screen according to the first aspect, the diffusion degree of the second diffusion layer is smaller than the diffusion degree of the diffusion layer of the Fresnel lens sheet.
According to the present invention, the degree of diffusion is such that the first diffusion layer> the diffusion layer of the Fresnel lens sheet> the second diffusion layer, and the diffusion degree of the first diffusion layer that is most effective in reducing scintillation is determined. Since the diffusion level of the Fresnel lens sheet and the diffusion layer of the second diffusion layer, which are maximized and easily affect the resolution and brightness, are suppressed, the diffusion level can be set efficiently.

According to a third aspect of the present invention, the projection display includes the transmissive screen according to the first or second aspect.
According to this invention, since the transmissive screen according to claim 1 or 2 is provided, the same effect as that of the invention according to claim 1 or 2 is provided.

  According to the transmissive screen and the projection display of the present invention, the diffusion degree of the first diffusion layer closest to the observation side of the light diffusion lens array sheet is set to the diffusion degree of the second diffusion layer closest to the light shielding layer and the Fresnel lens sheet. The refractive index difference between the light diffusing material of the light diffusing lens array sheet and the light diffusing substrate is different from that of the light diffusing material of the Fresnel lens sheet and the light diffusing substrate. Since the difference is smaller than the refractive index difference, there is an effect that scintillation can be reduced while maintaining good brightness.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

A transmissive screen and a projection display according to an embodiment of the present invention will be described.
FIG. 1 is a schematic cross-sectional explanatory diagram including an optical axis of a projection optical system for explaining a projection display according to an embodiment of the present invention. FIG. 2 is a cross-sectional explanatory view taken along the direction perpendicular to the plane of FIG. 1 for explaining the schematic configuration of the transmission screen according to the embodiment of the present invention. FIG. 3 is a partially enlarged view of FIG. 2 schematically illustrating the detailed configuration of the transmissive screen according to the embodiment of the present invention. Note that these drawings are schematic diagrams, and the shapes and dimensions are exaggerated (the same applies to the following).

As shown in FIG. 1, the rear projection television 10 (projection display) of the present embodiment exposes the casing 11 and the front side (right side in FIG. 1) to the outside of the casing 11 and the rear side (FIG. 1). As a light source for projecting projection light to the rear surface of the transmissive screen 20. The transmissive screen 20 has a substantially rectangular flat plate shape with the left side exposed to the inside of the housing 11. The projector 12 is also provided in the housing 11 and includes, for example, two reflecting mirrors 13 and 14 that deflect the optical path of the projection light projected from the projector 12.
As the projector 12, an appropriate projector can be adopted. For example, a display device such as an LCD, an LCOS (LCD on Silicon), a DMD (digital micromirror device), or the like is used. Thus, an MD projector that projects the modulated projection light from the rear side of the transmissive screen can be suitably employed.
In the following, for convenience of referring to the direction, the vertical direction of FIG. 1 is changed to the vertical direction (vertical direction) of the screen based on the normal arrangement posture of the rear projection television 10 and the viewing posture of the viewer, and FIG. The direction perpendicular to the paper surface may be referred to as the left-right direction (horizontal direction) of the screen.

Here, when there is no deflection by the reflecting mirrors 13 and 14, the arrangement position of the projector 12 is optically equivalent to the position of the two-dot chain line in FIG. 1, and in the following, unless otherwise specified. A description will be given based on an appropriate optical arrangement.
That is, the optical axis P1 of the transmissive screen 20 that coincides with the lens optical axis of the Fresnel lens sheet 30 to be described later is in a position translated downward from the center P2 of the transmissive screen 20, and the projector 12 has the optical axis P1. On the upper side, the transmissive screen 20 is disposed at a predetermined distance from the incident surface to the back side (left side in FIG. 1).

As shown in FIG. 2, the transmissive screen 20 includes a Fresnel lens sheet 30 having a Fresnel lens portion 31 that adjusts the direction of incident light to be emitted, and the emitted light from the Fresnel lens sheet 30 in the horizontal direction of the screen. And a lenticular lens sheet 40 (light diffusion lens array sheet) that is an optical member having a lens portion 44 that diffuses in the vertical direction (the vertical direction in FIG. 2) and the vertical direction (the vertical direction in FIG. 2).
The Fresnel lens sheet 30 and the lenticular lens sheet 40 are sequentially arranged from the rear side (left side in FIG. 2) to the front side (right side in FIG. 2) of the transmissive screen 20, and are also substantially parallel to each other. . In the following, the Fresnel lens sheet 30 side direction will be referred to as the light source side direction and the lenticular lens sheet 40 side direction will be referred to as the observation side direction, respectively. That is, in the present embodiment, the projection light is transmitted from the light source side toward the observation side.
Here, since FIG. 2 is a schematic diagram, the Fresnel lens portion 31 and the lens portion 44 are drawn so as to be separated from each other. However, if they are separated too much, the image will be blurred. It is preferable to have a configuration that can be in contact with each other and supported.

  As shown in FIG. 2, the Fresnel lens sheet 30 includes a third diffusion layer 33 (a diffusion layer of the Fresnel lens sheet), a substrate unit 32, and a Fresnel lens unit 31 arranged in that order from the incident light incident side. The layer 33 and the Fresnel lens portion 31 are bonded to the front and back bonding surfaces of the substrate portion 32. The Fresnel lens portion 31 is disposed to face the lenticular lens sheet 40.

The third diffusion layer 33 is for diffusing light while transmitting incident projection light. For example, a light diffusion layer or a light diffusion member formed in a layer shape, a plate shape, or a sheet shape having light diffusibility is employed. be able to. In this embodiment, as shown in FIG. 3, for example, a resin in which a filler 33b (light diffusing material) having a refractive index different from that of the base material 33a is dispersed inside a transparent base material 33a (light diffusing base material). Are stacked on the substrate portion 32.
The diffusion degree H ₃₃ of the third diffusion layer 33 of the present embodiment is a haze value and is set to a value of 50% to 70%. The degree of diffusion can be appropriately set from the above range by setting the prescription of the diffusion layer.
In addition, by appropriately selecting the material of each of the base material 33a and the filler 33b of the third diffusion layer 33, the refractive index difference Δn _F = | n _33a −n _33b | A range of 0.10 is preferred. Here, n _33a and n _33b are the refractive indexes of the base material 33a and the filler 33b, respectively.
As a material of the base material 33a, an appropriate transparent resin can be adopted, and for example, methyl methacrylate-styrene copolymer resin (MS resin) can be suitably adopted. For example, MS resin containing 60% of methyl methacrylate (MMA) and n _33a = 1.53 can be used.
As a material of the filler 33b, an appropriate filler having a refractive index different from that of the base material 33a can be employed. For example, an organic filler having an average particle size of 10 μm and n _33b = 1.50 can be suitably used. In this case, Δn _F = 0.03. Further, if an MS resin of n _33a = 1.57 is used as the base material 33a and an organic filler of n _33b = 1.47 is used as the filler 33b, Δn _F = 0.10.

Note that light diffusion includes internal diffusion caused by a light diffusing material inside the diffusion layer and external diffusion caused by irregularities on the incident and exit surfaces of the diffusion layer. The unevenness of the incident / exit surface includes, for example, unevenness intentionally formed by mat processing or the like, and unevenness formed by exposing the light diffusing material from the base material.
In order to reduce scintillation, both internal diffusion and external diffusion are effective. Therefore, the diffusion layer according to this embodiment has a configuration in which appropriate irregularities are provided on the incident / exit surface in order to achieve a necessary degree of diffusion. It is good.
The unevenness level due to exposure of the light diffusing material can be controlled by using a mixture of a spherical material such as an organic filler and an irregular shape such as an inorganic filler as the light diffusing material. For example, instead of the filler 33b, a mixture of organic resin beads and inorganic fillers such as talc and glass beads at an appropriate blending ratio may be used.
However, since external diffusion causes a loss of light quantity at the entrance / exit surface, from the viewpoint of light efficiency, the unevenness is controlled as described above so that the internal diffusion is larger than the external diffusion. preferable. In this embodiment, when external diffusion is added by the mixed filler as described above, for example, an unevenness level of about ten-point average roughness Rz = 3 to 6 is preferable.

The substrate part 32 is a light-transmitting substrate for supporting the Fresnel lens part 31. And the Fresnel lens part 31 is formed in the back surface side of the surface in which the 3rd diffused layer 33 was formed.
As a material of the substrate part 32, any material can be used as long as it is a transparent plate member. For example, MS resin or the like can be preferably used, but a substrate such as glass can also be used.

The Fresnel lens portion 31 is formed in a substantially serrated shape whose cross section including the optical axis is symmetric with respect to the optical axis. When viewed from the optical axis direction, the Fresnel lens portion 31 is arranged concentrically around the optical axis P1 (see FIG. 2). , Which forms a ring zone.
The sawtooth lens surface is composed of, for example, a lens surface such as a spherical surface or an aspherical surface that forms part of a convex lens, and a substantially cylindrical surface along the optical axis P1, depending on design conditions, and is arranged at the focal position. The projection light emitted from can be made substantially parallel light.

The Fresnel lens sheet 30 can be manufactured, for example, as follows.
First, for example, an ultraviolet curable resin is supplied to a mold for forming the shape of the Fresnel lens portion 31. Then, the substrate portion 32 having the third diffusion layer 33 formed on one surface is disposed so that the other surface is in close contact with the ultraviolet curable resin, and the substrate portion 32 is pressed by, for example, a roller as necessary. Drain excess UV curable resin. In this state, ultraviolet rays are irradiated from the UV illumination light source through the substrate portion 32 to cure the ultraviolet curable resin. Then, after the ultraviolet curable resin is cured, the mold is removed from the mold. In this way, the Fresnel lens part 31 to which the shape of the mold is transferred is formed on the substrate part 32.

Next, the lenticular lens sheet 40 will be described.
As shown in FIG. 3, the lenticular lens sheet 40 includes a lens portion 44, a lens substrate 42, a black stripe (BS) layer 45 (light shielding layer), an adhesive layer 46, and a second diffusion layer 48 (from the Fresnel lens sheet 30 side. The diffusion layer of the light diffusion lens array sheet), the first diffusion layer 49 (the diffusion layer of the light diffusion lens array sheet), the transparent layer 50, and the surface coat layer 51 are arranged in layers in this order.

The lens unit 44 includes a plurality of cylindrical lenses 43 having a substantially semi-cylindrical shape arranged in parallel with each other and extended in the vertical direction (vertical direction, vertical direction in the drawing), and the incident surface of the lenticular lens sheet 40. Is configured.
With such a configuration, the projection light emitted from the Fresnel lens sheet 30 is collected in the horizontal direction (horizontal direction, vertical direction in the drawing) of the screen, and then emitted toward the second diffusion layer 48 while diffusing in the horizontal direction. It can be done.

The BS layer 45 extends in a stripe shape along the generatrix direction of the cylindrical lens 43 on the back surface side of the lens substrate 42 provided with a plurality of cylindrical lenses 43 on the front surface. A black stripe that is shielded in a stripe shape by an appropriate range is formed by a light absorption band. Between each BS layer 45, a light-transmitting adhesive layer 46 that also serves as an adhesive layer for bonding the second diffusion layer 48 is provided. Since the adhesive layer 46 is formed as a thin layer, the BS layer 45 and the second diffusion layer 48 are provided in close proximity to each other. The focal position of the cylindrical lens 43 is set in the range where the vignetting by the BS layer 45 does not occur, or in the vicinity of the boundary of the light transmitting portion 47 or the boundary surface where the light transmitting portion 47 and the second diffusion layer 48 are in contact.
Therefore, the projection light collected by the cylindrical lens 43 is imaged in the light transmission part 47 or in the vicinity of the boundary surface between the light transmission part 47 and the second diffusion layer 48, and then propagates as diverging light. It proceeds toward the second diffusion layer 48.

The second diffusion layer 48 is for diffusing the projection light transmitted through the light transmission portion 47 in the vicinity of the focal position before being diffused by the first diffusion layer 49. In the present embodiment, a light diffusing plate member in which a light diffusing material is dispersed in the thickness direction can be employed.
In this embodiment, as shown in FIG. 3, for example, a resin in which a filler 48b (light diffusing material) having a refractive index different from that of the base material 48a is dispersed inside a transparent base material 48a (light diffusing base material). Is formed into a plate shape having a thickness t. Therefore, diffusion of the projection light transmitted through the light transmitting portion 47 starts from the boundary surface with the light transmitting portion 47, and the diffusion proceeds within the thickness t.
In order to suppress scintillation, the thickness t allows the first diffusion layer 49 to be disposed at an appropriate distance from the third diffusion layer 33 and supports the second diffusion layer 48 to provide the lenticular lens sheet 40 with appropriate rigidity. The thickness is set so as to function as a substrate. For example, when the base material 48a is MS resin, about 0.5 mm ≦ t ≦ 3 mm is preferable.

Diffusion degree _{H 48} of the second diffusion layer 48 and the third diffusion layer 33, less than the diffusion degree _{H 33, H 49} in the first diffusion layer 49, the substrate 48a and the refractive index difference between the filler 48b Δn _L2 = _{| n 48a} −n _48b | is set to be smaller than the refractive index difference Δn _F of the third diffusion layer 33 and substantially equal to the refractive index difference Δn _L1 of the first diffusion layer 49.
In the present embodiment, for example, the diffusion degree _{H 48} is the haze value, it is preferable to set to a value between 10% to 30%. For example, H ₄₈ = 20% is set.
As a material of the base material 48a, an appropriate transparent resin or the like can be used, and for example, an MS resin can be preferably used. For example, a material of n _48a = 1.53 can be used for MS resin containing 60% MMA.
As a material of the filler 48b, an appropriate filler having a refractive index different from that of the base material 48a can be employed. For example, an organic filler having an average particle size of 10 μm and n _48b = 1.55 can be suitably used.
In this case, Δn _L2 = 0.02.

The first diffusion layer 49 is a diffusion layer provided on the most observation side of the lenticular lens sheet 40, is formed on the observation side surface of the second diffusion layer 48, and is diffused horizontally and vertically by the second diffusion layer 48. Is provided to diffuse the projected light into a range of a required viewing angle.
In order to reduce scintillation, the interlayer distance between the third diffusion layer 33 and the first diffusion layer 49 is preferably set to 1 mm or more.
In this embodiment, as shown in FIG. 3, for example, a resin in which a filler 49b (light diffusing material) having a refractive index different from that of the base material 49a is dispersed inside a transparent base material 49a (light diffusing base material). Is coated on the second diffusion layer 48.
The diffusion degree H ₄₉ of the first diffusion layer 49 of the present embodiment is a haze value and is set to a value of 70% to 90%. The magnitude of the diffusion degree can be set in the above range in the same manner as the third diffusion layer 33. For example, H ₄₉ is set to 85%.
Further, by appropriately selecting the material of each of the base material 49a and the filler 49b of the first diffusion layer 49, the refractive index difference Δn _L1 = | n _49a −n _49b | A range of 0.03 is preferable. Here, n _49a and n _49b are the refractive indexes of the base material 49a and the filler 49b, respectively.
As a material of the base material 49a and the filler 49b, an appropriate transparent resin can be adopted, but in the present embodiment, the same material as that of the base material 48a and the filler 48b is used. Therefore, Δn _L1 = 0.02.

  Suitable thicknesses of the third diffusion layer 33, the second diffusion layer 48, and the first diffusion layer 49 are set within the ranges of 50 μm to 300 μm, 0.5 mm to 3.0 mm, and 50 μm to 300 μm, respectively. A suitable distance between the third diffusion layer 33 and the first diffusion layer 49 is set within a range of 0.8 mm to 3.0 mm.

  The transparent layer 50 is for smoothing fine irregularities formed by exposing the filler 49b to the surface on the observation side of the first diffusion layer 49, and facilitating the formation of the surface coat layer 51. For example, an acrylic copolymer resin such as MS resin can be formed by coextrusion molding or coating on the first diffusion layer 49 with a thickness of 50 μm to 300 μm.

  The surface coat layer 51 is various coat layers that are provided as necessary to satisfactorily finish the surface properties of the transmission screen 20. For example, a hard coat (HC) layer for imparting scratch resistance to a surface with a pencil hardness of about 3H or more, an antiglare (AG) layer for preventing reflection, and an antistatic (AS) layer for preventing dust adhesion A coat layer having a function such as a single layer or a plurality of layers is formed.

Next, the operation of the rear projection television 10 of the present embodiment will be described focusing on the operation of the transmissive screen 20.
As shown in FIG. 1, the projection light emitted from the projector 12 is deflected by the reflecting mirrors 13 and 14 and projected from the oblique lower side to the transmissive screen 20. Then, the light is incident on the third diffusion layer 33 of the Fresnel lens sheet 30, undergoes refraction and reflection, is diffused in the third diffusion layer 33 in which the filler 33 b is dispersed, and passes through the substrate portion 32.
The projection light transmitted through the substrate portion 32 is diffused according to the diffusion degree of the third diffusion layer 33, and enters the Fresnel lens portion 31 in a state where the diffusion has progressed by the thickness of the substrate portion 32. Then, the light is made substantially parallel light by being refracted by the Fresnel lens portion 31 and is emitted toward the lenticular lens sheet 40 in a direction substantially parallel to the optical axis P1.

The projection light incident on the lenticular lens sheet 40 is condensed in the left-right direction (horizontal direction) of the screen by the lens unit 44 and is formed into a stripe shape. Unnecessary non-condensing components are shielded by the BS layer 45, and the condensing components are transmitted through the light transmitting portion 47. The projected light is linearly imaged in the light transmitting portion 47 or in the vicinity of the boundary surface between the adhesive layer 46 and the light transmitting portion 47 according to the focal position of the cylindrical lens 43, and then the screen is moved in the horizontal direction of the screen. It becomes divergent light.
When the projection light is incident on the second diffusion layer 48, it is further diffused in the horizontal direction of the screen and also in the vertical direction (vertical direction), and the second diffusion is performed within the thickness t of the second diffusion layer 48. Diffusion gradually proceeds according to the diffusion degree of the layer 48 and reaches the first diffusion layer 49.
When the diffused light reaches the first diffusion layer 49, it is relatively diffused according to the degree of diffusion of the first diffusion layer 49, passes through the transparent layer 50 and the surface coat layer 51, and the outside of the lenticular lens sheet 40. Is emitted.
Therefore, projection light that diffuses in a predetermined angle range in the vertical direction and the horizontal direction with respect to the normal direction of the screen is emitted from the transmissive screen 20 to the observation side. It is possible to appreciate the projection light within the range of the viewing angle.

In the present embodiment, by providing a plurality of diffusion layers on the transmission screen 20 and distributing the degree of diffusion to each, it is possible to reduce scintillation while maintaining good resolution, contrast, and brightness.
First, if the diffusion degree of the third diffusion layer 33 provided on the Fresnel lens sheet 30 side is too large, the image of the projected light is blurred and affects the resolution, and the non-shielded light is blocked by the BS layer 45 due to diffusion. Condensed components increase, light efficiency deteriorates, and contrast and brightness decrease.
Therefore, in order to prevent such a decrease in resolution, contrast, and brightness, the diffusion degree H ₃₃ of the third diffusion layer 33 is set smaller than H ₄₉ of the first diffusion layer 49. Since the lenticular lens sheet 40 also has the second diffusion layer 48, this can ensure that the degree of diffusion by the diffusion layer on the Fresnel lens sheet 30 side is smaller than the degree of diffusion by the diffusion layer on the lenticular lens sheet 40 side. It is set.

On the other hand, even with the same degree of diffusion, the amount diffused to the periphery of a certain diffusion angle range is smaller than the distribution evenly diffused to a certain diffusion angle range (hereinafter referred to as “uniform distribution type”). The distribution intensively diffused in the vicinity of the value (hereinafter referred to as “concentrated distribution type”) improves the light efficiency by reducing the light loss because the non-condensing component shielded by the BS layer 45 is reduced. can do.
In this embodiment, in order to improve the light efficiency according to this principle, it is set so that H ₃₃ <H ₄₉ and Δn _F > Δn _L1 .
In general, the greater the difference in refractive index between the light diffusing material and the light diffusing substrate, the greater the refracting action or reflecting action at each interface and the wider the diffusion angle. Therefore, if the degree of diffusion is the same, the greater the difference in refractive index, the lower the dispersion concentration of the light diffusing material and the wider the space between the light diffusing materials.
In the present embodiment, in combination with H ₃₃ <H ₄₉ , the difference in spacing between the light diffusing materials due to the difference in refractive index appears more than in the case where the degree of diffusion is equivalent. Is a relatively sparse state in which the dispersion concentration of the filler 33b is low, and the first diffusion layer 49 is in a relative dense state in which the dispersion concentration of the filler 49b is high.
Therefore, the projection light transmitted through the third diffusion layer 33 receives a relatively concentrated distribution type diffusion, becomes a non-parallel component in the Fresnel lens portion 31, and has a large diffusion angle that is scattered by the BS layer 45. Is incident on the cylindrical lens 43 and the first diffusion layer 49 performs diffusion corresponding to the finally required viewing angle. Therefore, the light efficiency in diffusion is improved.

Next, the scintillation reducing action of such a configuration will be described.
Scintillation is a phenomenon in which high-intensity light in the form of minute spots that is not present in the original image is observed and the image flickers and feels glaring. The main cause is that there is a minute luminance unevenness formed by a light beam deviating from the normal optical path due to a manufacturing error or a minute defect of an optical element in the transmission screen being emitted in a specific direction within a viewing angle range. Conceivable.
In the present embodiment, as described above, as well as larger than the degree of diffusion of the most viewing side of the diffusion layer is a diffusion degree H ₄₉ the other diffusion layer of the first diffusion layer 49, a first diffusion layer 49 Filler 49b is a relatively dense state in which the dispersion concentration is high. Therefore, even if minute spot-like high-intensity light traveling in a specific direction is generated before reaching the first diffusion layer 49, strong diffusion of the uniform distribution type is performed in the first diffusion layer 49. High-intensity light is less likely to be emitted in a specific direction on the side, and combined with the fact that the projection light is diffused to some extent by the third diffusion layer 33, scintillation is reduced.

On the other hand, the first diffusion layer 49 must realize a desired viewing angle. That is, if the degree of diffusion is increased too much in order to eliminate scintillation, the viewing angle is expanded to an unnecessary range, and the light amount gain is reduced on the observation side, resulting in a dark image. In addition, the scintillation reduction effect is improved as the distance between the third diffusion layer 33 and the first diffusion layer 49 is increased. However, the first diffusion layer 49 is further away from the focal position of the cylindrical lens 43, and image blurring easily occurs. .
Therefore, in the present embodiment, in the lenticular lens sheet 40, the second diffusion layer 48 having a diffusion degree H ₄₈ of H ₄₈ <H ₃₃ is provided so that a part of the diffusion action of the first diffusion layer 49 can be shared. . Further, by providing the second diffusion layer 48 in the vicinity of the BS layer 45, the projection light near the focal position of the cylindrical lens 43 collected by the light transmitting portion 47 sandwiched between the BS layers 45 is second. The arrangement allows the diffusion layer 48 to diffuse on the incident surface.
Therefore, scintillation can be suppressed without unnecessarily widening the viewing angle due to the diffusion of the first diffusion layer 49, and the first diffusion layer is in a state where the divergence by the cylindrical lens 43 has progressed at a position away from the focal position. Compared with the case of diffusing only by 49, image blurring is reduced. Therefore, both suppression of scintillation and improvement of resolution can be achieved.
At this time, it is more preferable to make the incident surface of the second diffusion layer 48 coincide with the focal position of the cylindrical lens 43 because image blurring can be minimized.

Next, a modification of this embodiment will be described.
FIG. 4 is a partially enlarged view of a cross-sectional view in the same direction as FIG. 3 for explaining a detailed configuration of a transmission screen according to a modification of the embodiment of the present invention.

The transmissive screen 200 of this modification includes a lenticular lens sheet 400 (light diffusion lens array sheet) instead of the lenticular lens sheet 40 of the transmissive screen 20 of the above embodiment. Hereinafter, a description will be given focusing on differences from the above embodiment.
The lenticular lens sheet 400 includes a second diffusion layer 52 and a transparent substrate 53 instead of the second diffusion layer 48 of the lenticular lens sheet 40.

As shown in FIG. 4, the second diffusion layer 52 is a layered or sheet-shaped light diffusing member having a light diffusibility that is thinner than that of the second diffusion layer 48. The filler 52b is dispersed in a base material 52a made of a transparent resin, for example, MS resin, and the diffusion degree H ₅₂ and the refractive index difference Δn ₅₂ = | n set in the same range as the second diffusion layer 48. _52a- n _52b |. Here, n _52a and n _52b are the refractive indexes of the base material 52a and the filler 52b, respectively.
For example, when the base material 52a is an MS resin, the thickness of the second diffusion layer 52 is preferably about 50 μm to 300 μm. For example, the second diffusion layer 52 may be formed by laminating or coating the transparent substrate 53 by coextrusion. it can.

The transparent substrate 53 is a support substrate for disposing the second diffusion layer 48 and the first diffusion layer 49 apart from each other and ensuring the rigidity necessary for the lenticular lens sheet 400. The transparent substrate 53 is made of a light-transmitting resin substrate. Become. As the material of the resin, for example, MS resin can be adopted. For example, in the case of MS resin, the thickness of the transparent substrate 53 is preferably 0.5 mm to 3 mm.
Then, the second diffusion layer 52 is coextruded or coated on one surface, and the first diffusion layer 49 is coextruded or coated on the other surface.

According to this modification, the projection light is diffused by the second diffusion layer 52 that is thinner than the second diffusion layer 48, and the diffused light is advanced by the thickness of the transparent substrate 53. 49, and is emitted through a transparent layer 50 and a surface coat layer 51 to a predetermined viewing angle range.
Therefore, the light diffused in the second diffusion layer 52 is not further internally diffused in the transparent substrate 53, so that the image information in the second diffusion layer 52 is further diffused and not disturbed. 1 diffusion layer 49 is reached. Therefore, the resolution can be further improved compared to the above embodiment.
More preferably, the incident surface of the second diffusion layer 52 is disposed at the focal position of the cylindrical lens 43 as in the case of the second diffusion layer 48.

Next, the evaluation result of the optical characteristic of the Example of the transmission type screen 20 of embodiment of this invention and the comparative example different from this invention is demonstrated.
In the following examples and comparative examples, the cross-sectional configuration is the same as in FIG. 3, and the diffusion degree and refractive index difference of the third diffusion layer 33, the second diffusion layer 48, and the first diffusion layer 49 are as shown in the table below. It has changed.
Here, the thicknesses of the third diffusion layer 33, the second diffusion layer 48, and the first diffusion layer 49 are 100 μm, 130 μm, and 100 μm, respectively. The distance between the third diffusion layer 33 and the first diffusion layer 49 is 3.0 mm.

The evaluated optical characteristic items are peak gain, total light transmittance (%), screen transmission efficiency, vertical viewing angle (half width) (°), hot band, scintillation, and resolution. Here, the peak gain (Gs) is one of indices indicating the performance of the screen, and indicates the highest numerical value of the screen gain (usually, the gain value in front of the screen facing the screen).
The practical allowable range of each measurement value is a peak gain of 4 or more, a total light transmittance of 60% or more, and a vertical viewing angle of 7 ° or more, preferably 8 ° or more.
Evaluation of screen transmission efficiency is a sensory evaluation of practical usability in consideration of peak gain and total light transmittance. ○, △, × are good, slightly inferior, and no practicality, respectively. Represents.
The evaluation of the hot band is a phenomenon in which the horizontal direction in the center of the screen is bright and the horizontal direction in the upper and lower peripheral parts is dark. ◯, △, and x represent absence, presence, and presence, respectively. If there is a hot band, scintillation can be easily seen at the center of the screen where the brightness is high, so it is desirable that there is no hot band. The quantitative characteristic is related to the vertical viewing angle.
The scintillation evaluation is a sensory evaluation of the conspicuousness, and ◯, Δ, and x represent the inconspicuous, slightly conspicuous, and conspicuous, respectively.
The resolution is evaluated by sensory evaluation by visually projecting an actual image, and ◯, Δ, and X represent good, slightly bad, and bad, respectively.
The above measurement and evaluation results are shown in the table below.

As shown in the above table, in Examples 1 to 4, although the degree of diffusion of the first diffusion layer 49 is higher than that of the comparative example, the evaluation of each optical characteristic is in a practically good range, or more It turns out that it is in the preferable range. That is, scintillation is reduced and brightness and resolution are good.
On the other hand, in Comparative Examples 1 to 4, in which the degree of diffusion of the third diffusion layer 33 is larger than that of the first diffusion layer 49, the screen is also used in Comparative Example 3 in which the total light transmittance related to brightness and contrast is low and the peak gain is relatively large. Evaluation of transmission efficiency has not reached the practical range. All the resolutions are Δ, and the scintillation is Δ or ×.
In Comparative Example 5, since the degree of diffusion of the third diffusion layer 33 is low, the brightness relationship and resolution characteristics are slightly good, but the scintillation is Δ.
In Comparative Example 6, since the degree of diffusion of the third diffusion layer 33 and the first diffusion layer 49 is high, the scintillation is ◯, but the results of the brightness relationship and the resolution are not so good.

In the above description, the first diffusion layer 49, the third diffusion layer 33, and the second diffusion layer 52 have been described as being formed by lamination or coating by coextrusion. However, the present invention is not limited to this. For example, a light diffusing material may be dispersed in a light diffusing substrate to form a film sheet, which may be adhered to the surface of the substrate portion to be disposed via a light-transmitting adhesive or pressure-sensitive adhesive.
Further, for example, a forming method in which a light diffusing material is dispersed in a resin of a light diffusing substrate and transferred to a substrate portion from a transfer sheet provided on a release sheet can be employed.
Furthermore, it is also possible to employ a light-transmitting adhesive or pressure-sensitive adhesive in which a light diffusing material is dispersed.

  In the above description, the diffusion layer has a total of three layers, but three or more layers may be provided.

It is a schematic cross section explanatory drawing containing the optical axis of the projection optical system for demonstrating the projection type display which concerns on embodiment of this invention. FIG. 2 is a cross-sectional explanatory diagram along a direction perpendicular to the paper surface in FIG. 1 for explaining a schematic configuration of the transmission screen according to the embodiment of the present invention. It is the elements on larger scale of FIG. 2 typically expressed in order to demonstrate the detailed structure of the transmissive screen which concerns on embodiment of this invention. It is the elements on larger scale of the same direction sectional view as Drawing 3 for explaining the detailed composition of the transmission type screen concerning the modification of the embodiment of the present invention.

Explanation of symbols

10 Rear projection television (projection display)
12 Projector (light source)
20, 200 Transmission type screen 30 Fresnel lens sheet 31 Fresnel lens part 33 Third diffusion layer (diffusion layer of Fresnel lens sheet)
33a, 48a, 49a, 52a Base material (light transmission base material)
33b, 48b, 49b, 52b Filler (light diffusing material)
40, 400 Lenticular lens sheet (light diffusion lens array sheet)
42 Lens substrate 43 Cylindrical lens (lens)
44 Lens part 45 BS layer (light shielding layer)
46 Adhesive layer 47 Light transmission part 48, 52 Second diffusion layer (diffusion layer of light diffusion lens array sheet)
49 1st diffusion layer (diffusion layer of light diffusion lens array sheet)
50 Transparent layer 51 Surface coat layer 53 Transparent substrate P1 Optical axis

Claims (3)

A Fresnel lens sheet that makes the projection light projected from the light source substantially parallel light, and a plurality of lenses that diverge the projection light that is made substantially parallel light by the Fresnel lens sheet are arranged, and a light shielding layer in the vicinity of the plurality of lenses A transmissive screen provided with a diffusion layer in which a light diffusing material is dispersed in a light diffusing substrate, respectively, on the Fresnel lens sheet and the light diffusing lens array sheet. There,
The diffusion layer of the light diffusion lens array sheet includes a plurality of at least a first diffusion layer located closest to the observation side and a second diffusion layer provided closest to the light shielding layer of the light diffusion lens array sheet Consisting of a diffusion layer,
The diffusion degree of the first diffusion layer is larger than any diffusion degree of the other diffusion layers of the light diffusion lens array sheet and the diffusion layer of the Fresnel lens sheet,
And the refractive index difference between the light diffusing material and the light diffusing substrate in each diffusion layer of the light diffusing lens array sheet is the difference between the light diffusing material and the light diffusing substrate of the diffusion layer of the Fresnel lens sheet. A transmission screen characterized by having a smaller configuration than the difference in refractive index.   The transmissive screen according to claim 1, wherein a diffusion degree of the second diffusion layer is smaller than a diffusion degree of the diffusion layer of the Fresnel lens sheet.   A projection display comprising the transmissive screen according to claim 1.

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