JP2006235036A - Transmission type screen and rear projection type display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission type screen and a rear projection type screen that hardly cause a deterioration in picture quality due to the occurrence of scintillation, a decease in resolution, a decrease in lightness, etc., even when made lightweight, thin, or high in definition. <P>SOLUTION: A Fresnel lens sheet which makes video light projected on an observation side from a light source into nearly parallel light and a light-diffusing lens array sheet having an array of a plurality of lenses for diffusing the nearly parallel light of the video light from the Fresnel lens sheet are arranged closely to each other, light diffusion portions which are arranged in the optical path of the video light and diffuse the video light are provided at least on the light source side of the Fresnel lens sheet and the observation side of the light diffusing lens array sheet, and the thickness of the Fresnel lens sheet in the light transmitting direction is larger than the thickness of the light diffusion lens array sheet in the light transmitting direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Conventionally, a rear projection television is known as a projection display with a transmissive screen. In recent years, a rear projection television has been used as a light source from a projector having a small projection lens diameter represented by a liquid crystal projector or a light valve. The projected image light is reflected by a reflecting mirror and incident on the rear surface of a transmissive screen having a substantially rectangular flat plate shape, so that an observer located on the front side of the transmissive screen transmits the transmissive screen. Thus, the image light emitted can be observed.

The transmissive screen includes a Fresnel lens sheet that adjusts the direction of incident light and emits the light as substantially parallel light, and a lenticular lens sheet (light diffusion lens array) that diffuses light emitted from the Fresnel lens sheet. A light diffusion layer is provided on each of the Fresnel lens sheet and the lenticular lens sheet.
For example, Patent Document 1 describes a transmission screen including a Fresnel lens sheet having a lens portion provided on a light diffusion substrate on the light source side, and a light diffusion substrate bonded with a horizontal lenticular sheet and an adhesive layer. Yes. The light diffusing substrate provided with the Fresnel lens sheet is about 0.5 mm to 2 mm in terms of light diffusion characteristics and rigidity. The light diffusing substrate of the transmissive screen includes a first light diffusing layer and a second light diffusing layer in which two resin layers containing a light diffusing material are sequentially laminated on a transparent resin substrate. These are laminated without being separated.
On the other hand, in Patent Document 2, for the purpose of reducing the occurrence of scintillation and preventing the reduction of resolution and gain, the light diffusion portions formed on the Fresnel lens and the lenticular lens sheet are separately arranged, and the diffusion of the light diffusion portion is performed. It is described that the degree of light source side is smaller than the observation side. However, when it is strongly required to reduce the weight, thickness, and definition of a transmissive screen that is not described in Patent Document 2, along with rigidity and weather resistance, the generation of scintillation is reduced, and resolution and gain are reduced. It is necessary to have a configuration that satisfies the reduction prevention and the reduction in luminance variation at the same time.
JP 2002-236319 A JP 2004-94207 A

However, the conventional transmission screen and rear projection display as described above have the following problems.
In recent years, liquid crystal projectors used as light sources and projectors with a small projection lens diameter, such as light valves, have come to be used, and light diffusion parts provided on transmissive screens cause flickering of images called scintillation or speckle. Outbreaks have become conspicuous and countermeasures have been sought. As a countermeasure, there is mainly a method of adding a large amount of a light diffusing agent to the lens sheet, but there is a problem that a decrease in brightness or a decrease in resolution occurs. Further, there is a strong demand for light-weight, thin, and high-definition transmission screens.
However, the light diffusing substrate and the light diffusing portion are provided on the Fresnel lens sheet and the lenticular lens sheet as in the technique described in Patent Document 1, for example, so that a transmissive screen with a large viewing angle can be obtained. From the above point, since a relatively thick light diffusion substrate such as 0.5 mm to 2 mm is required, there is a problem that the transmission screen becomes heavy and the cost is increased. Further, when the light diffusion substrate becomes thick and the diffusion degree is increased, there is a problem that the focus of the transmissive screen becomes unsatisfactory, the resolution and sharpness (sharpness) deteriorate, and the brightness of the screen is affected.
Further, in order to achieve high definition, it is necessary to dispose the Fresnel lens sheet and the lenticular lens sheet close to each other, but in the technique described in Patent Document 1, scintillation deteriorates if they are disposed close to each other. There is. Scintillation is a phenomenon in which the brightness of the image light changes with the change of the observer's viewpoint, and the image looks glaring.
Further, Patent Document 2 defines the degree of diffusion depending on the position of the light diffusing unit, but it is said that the effect of the light diffusing unit when the transmissive screen is reduced in weight, thickness, and definition. However, it is impossible to satisfy both the reduction of the occurrence of scintillation, the reduction in luminance variation, and the prevention of reduction in resolution and gain at the same time, and there is a problem of occurrence of scintillation and reduction in resolution.

  The present invention has been made in view of the above-described problems, and even if the weight, thickness, and definition are improved, image quality is deteriorated due to generation of scintillation, resolution, brightness, etc. It is an object of the present invention to provide a transmission screen and a rear projection display that can be made difficult.

In order to solve the above-described problems, the invention described in claim 1 is a Fresnel lens sheet that makes image light projected from the light source to the observation side substantially parallel light, and an image that is made substantially parallel light by the Fresnel lens sheet. A light diffusing lens array sheet on which a plurality of lenses that diverge light are arranged, and a light diffusing portion that is arranged in the optical path of the image light and diffuses the image light are arranged at least on the observation side of the light diffusing lens array sheet And the thickness of the Fresnel lens sheet in the light transmission direction is larger than the thickness of the light diffusion lens array sheet in the light transmission direction.
According to the present invention, the thickness of the Fresnel lens sheet in the light transmission direction is made larger than the thickness of the light lens array sheet having a light diffusing portion for diffusing at least image light. The distance to the diffusion layer can be set, and thereby, it is possible to emit video light having both good viewing angles in reducing the occurrence of scintillation and preventing the resolution and brightness from being lowered.

According to a second aspect of the present invention, in the transmissive screen according to the first aspect, a light diffusion portion is formed on the light source side of the Fresnel lens sheet.
According to the present invention, by forming the light diffusing portion on the light source side, the incident of the noise light generated in the reflection process of the image light on the light incident surface of the Fresnel lens sheet or the projection process from the light source, or the interface of the lens sheet, It is also possible to reduce the influence of re-incidence of reflected light generated on the surface or the like, and further reduce the coherence in image light entering a projector with a small projection lens diameter represented by a light valve.
The light diffusing portion referred to in the present invention may include a surface diffusing surface or an interface diffusing surface for diffusing video light on the surface or interface, or may be composed only of a transmission diffusing layer. When the surface diffusion surface or the interface diffusion surface is included, the light diffusion portion can be thinned.

The invention according to claim 3 is the transmission type screen according to claim 1 or 2, wherein the thickness of the light diffusion lens array sheet is 0.30 to 0.85 with respect to the thickness of the Fresnel lens sheet. This is the configuration.
According to this invention, it can be said that there is a trade-off relationship between scintillation, resolution and brightness from the thicknesses of the Fresnel lens sheet and the light diffusing lens array sheet constituting the transmissive screen. The thickness is preferably larger than the thickness of the light diffusing lens array sheet, and the ratio thereof is preferably in the range of 0.30 to 0.85 with respect to the Fresnel lens sheet. In particular, 0.60 to 0.85 is more preferable. According to this, it is possible to provide a relationship suitable for reducing the scintillation and preventing the resolution and brightness from being lowered, as well as making the transmission screen lighter, thinner and higher definition.

According to a fourth aspect of the present invention, in the transmissive screen according to any one of the first to third aspects, the configuration of the light diffusion lens array includes at least a lens portion, a lens base material, a transparent base material, and a light diffusion portion. The configuration of the Fresnel lens sheet includes at least a lens portion, a lens base material, and a light diffusing portion, and all have a configuration in which the reference object of the thickness in the transmission direction excludes the lens portion.
According to the present invention, by identifying the configuration that most affects the image light transmitted through the transmissive screen, the transmissive screen is reduced in weight, thickness, and definition, and the scintillation is reduced and resolution and brightness are prevented from being reduced. It is possible to clarify the relationship suitable for

According to a fifth aspect of the present invention, in the transmissive screen according to any one of the first to fourth aspects, the degree of diffusion of the light diffusing portion is such that the Fresnel lens sheet side is smaller than the light diffusing lens array sheet side.
According to the present invention, in addition to the thickness of the Fresnel lens sheet and the light diffusing lens array sheet, at least one or both of the plurality of light diffusing portions are formed on the Fresnel lens sheet side smaller than the light diffusing lens array sheet side. Thus, the diffusion effect of the light diffusing unit on the light source side is not affected by the incident of noise light generated by the reflection of the image light on the light incident surface or the projection process from the light source or the lens sheet without reducing the resolution or brightness. In addition to reducing the influence of re-incidence of reflected light generated at the interface, surface, etc., it is possible to further reduce the coherence of image light incident from a projector having a small projection lens diameter, such as a liquid crystal projector or a light valve.

A sixth aspect of the present invention is the transmission type screen according to any one of the first to fourth aspects, wherein a diffusing function smaller than that of the light diffusing portion is given to any one of the configurations other than the light diffusing portion. is there.
According to the present invention, by providing a small diffusion function to the configuration other than the light diffusing unit, the light is incident from a projector having a small projection lens diameter, such as a liquid crystal projector or a light valve, without reducing resolution or brightness. Coherence in image light can be reduced.

The invention according to claim 7 is the transmissive screen according to any one of claims 1 to 6, wherein the light diffusion lens array sheet is a lenticular lens sheet in which a plurality of semi-cylindrical cylindrical lenses are arranged in parallel. A plurality of semi-cylindrical cylindrical lenses arranged in parallel, a plurality of lens array sheets in which the arrangement directions of the cylindrical lenses are orthogonal and arranged in the light transmission direction, and a plurality of semi-cylindrical cylindrical lenses are arranged in parallel A lens array sheet in which the first lens array and the second lens array are arranged on the same plane so that the length directions of the cylindrical lenses are orthogonal to each other and are integrated. .
According to the present invention, the image light collected by the Fresnel lens sheet is diffused in the horizontal direction and further in the vertical direction, the viewing angle is expanded, the viewing angle is expanded in other directions, and the scintillation is reduced. Decrease in resolution and brightness can be prevented.

The invention according to an eighth aspect is the transmission type screen according to any one of the first to sixth aspects, wherein the light diffusing portion is arranged in close contact with or close to another member.
According to the present invention, the light diffusing part can be formed independently without being in close contact or in an adhesive state.

The invention according to claim 9 is the transmission type screen according to any one of claims 1 to 8, wherein an optical functional layer such as a hard coat layer, an antireflection layer, an antistatic layer, or a colored layer is provided on the observation side outermost layer. Any one or more of them are formed in the same layer or multiple layers.
According to the present invention, by providing various optical functional layers as the outermost layer of the transmission screen of the present invention, the optical functional layer is not affected without affecting the effect of preventing the reduction of scintillation and the reduction of resolution and brightness. The effect of can be added.

According to a tenth aspect of the present invention, in the transmissive screen according to any one of the first to eighth aspects, the translucent substrate having at least one of the optical functional layers on the observation-side outermost layer is observed. It is the structure arrange | positioned in the side.
According to the present invention, the self-supporting of the Fresnel lens sheet and the light diffusing lens array sheet can be assisted, or the strength of the transmissive screen can be given, and the observing side of the transmissive screen, that is, the appearance texture can be improved. Can do.

The invention according to claim 11 comprises the transmissive screen according to any one of claims 1 to 10, a projector having a small projection lens diameter represented by a liquid crystal projector or a light valve as a light source, and This is a rear projection display in which image light projected from the camera to the observation side is displayed on an image via a transmission screen.
According to this invention, since the transmission screen according to any one of claims 1 to 10 is provided, the same effect as the invention according to any one of claims 1 to 3 is provided.

  According to the transmission screen and the rear projection display of the present invention, the thickness of the Fresnel lens sheet in the light transmission direction is made larger than the thickness of the light diffusion lens array sheet, thereby reducing scintillation and improving the resolution and brightness. It is possible to achieve the prevention of the decrease at the same time and to balance the both, and to provide an optimal screen configuration for reducing the weight, thickness and definition of the transmission screen.

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 rear projection display according to an embodiment of the present invention will be described.
FIGS. 1A and 1B are schematic cross-sectional explanatory views including an optical axis of a projection optical system for explaining a rear projection display according to the 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 first embodiment of the present invention. FIG. 3 is an explanatory cross-sectional view for explaining the schematic configuration of the transmission screen according to the second embodiment of the present invention. FIG. 4 is a graph showing the relationship between scintillation and resolution in the thickness of the transmission screen according to the third embodiment of the present invention. (1) to (3) in FIG. 5 are tables showing the state of scintillation, luminance variation, and resolution when the thicknesses of the Fresnel lens sheet and the light diffusing lens array sheet are changed. It is a table | surface which shows comprehensive evaluation based on the result of 1)-(3). FIG. 6 is an explanatory cross-sectional view for explaining a schematic configuration of a transmission screen according to the fourth embodiment of the present invention. FIG. 7 is an explanatory perspective view for explaining a schematic configuration of a transmission screen according to the fifth embodiment of the present invention. FIGS. 8A and 8B are cross-sectional explanatory views for explaining the schematic configuration of the transmission screen according to the sixth embodiment of the present invention. FIG. 9 is an explanatory cross-sectional view for explaining a schematic configuration of a transmission screen according to a seventh embodiment of the present invention. FIG. 10 is an explanatory cross-sectional view for explaining a schematic configuration of a transmission screen according to the eighth 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. 1A, the rear projection television 10 (rear projection type display) of the present embodiment exposes the casing 11 and the front side (the right side in FIG. 1) to the outside of the casing 11 and the rear side. A transmissive screen 20 having a substantially rectangular plate shape with the side (left side in FIG. 1) exposed to the inside of the housing 11, and image light is projected on the back surface of the transmissive screen 20 disposed in the housing 11. A projector 12 having a small projection lens diameter such as a liquid crystal as a light source, and two reflecting mirrors 13 and 14 that are arranged in the housing 11 and deflect the optical path of the image light projected from the projector 12. ing. An optical axis P1 of the transmissive screen 20 that coincides with a lens optical axis of a Fresnel lens sheet 30 (to be described later) constituting the transmissive screen 20 is in a position translated downward from the center P2 of the transmissive screen 20, and the projector 12 Are arranged at a predetermined distance from the incident surface of the transmission screen 20 to the back side (left side in FIG. 1) on the optical axis P1.
In the following, for the 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. A description will be given based on an appropriate optical arrangement.
1 (2) is a Fresnel lens sheet (not shown) in which the optical axis P1 is arranged at the center of the transmissive screen 20 of the rear projection TV 10 with a Fresnel lens sheet (not shown). In some respects, the groove bottom (not shown) of the Fresnel lens sheet is formed concentrically. This Fresnel lens sheet has the same configuration as that of the Fresnel lens sheet of the transmissive screen 20 except for the position of the optical axis P1 and the reflecting mirrors 15 and 16 having no deflection.
According to such a configuration, the optical axis of the projector 12 and the optical axis P1 of the Fresnel lens sheet.
Therefore, by forming the thickness forming portion substantially symmetrically with respect to the center P2 of the Fresnel lens sheet, the luminance distribution due to the difference in the height of the Fresnel lens portion and the luminance distribution due to the light source of the projector 12 are Has the advantage that can be corrected simultaneously

A transmissive screen 20 according to the first embodiment of the present invention shown in FIG. 2 includes a Fresnel lens sheet 30 having a Fresnel lens 31 (Fresnel lens portion) that adjusts the direction of incident light to be emitted light, and the Fresnel lens. A light diffusing lens array sheet 40 (particularly an optical member having a diffusing lens portion 44 for diffusing the light emitted from the sheet 30 in the left-right direction (vertical direction in FIG. 2) and the vertical direction (vertical direction in FIG. 2) of the screen. Unless otherwise stated, here, a lenticular lens sheet is exemplified.
The Fresnel lens sheet 30 and the light diffusing lens array sheet 40 are sequentially arranged from the back side (left side in FIG. 2) to the front side (right side in FIG. 2) of the transmissive screen 20 and are substantially parallel to each other. ing.
Here, the Fresnel lens 31 and the diffusing lens portion 44 are drawn so as to be separated from each other. However, if they are separated too much, the image is blurred, so it is preferable to make them as close as possible. It is more preferable to have a configuration in which a part of them can contact each other and support each other.

  As shown in FIG. 2, the Fresnel lens sheet 30 includes a transparent substrate 32 and a Fresnel lens portion 31 that are sequentially arranged from the incident side of the image light, and the Fresnel lens 31 and the transparent substrate 32 are joined at a joining surface 37. It is. The Fresnel lens 31 is opposed to the light diffusion lens array sheet 40.

The transparent substrate 32 is a substantially rectangular light-transmitting flat plate for supporting the Fresnel lens portion 31. One surface is formed of a smooth bonding surface 37 for bonding the Fresnel lens portion 31, and the other surface is formed of a flat bonding surface 38 for bonding the diffusion layer 33.
The material of the transparent substrate 32 may be any material as long as it is a transparent plate member. For example, an acrylic-styrene copolymer resin or the like can be suitably used.

  The Fresnel lens portion 31 has a plurality of lens portions in the optical axis direction that form 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, each lens portion 31A is arranged in a concentric circle shape centered on the optical axis or linearly in the horizontal direction, and an annular zone delimited by the groove bottom V is formed.

  The material of the Fresnel lens part 31 may be any resin as long as the light-transmitting base material resin (lens base material) is a light-transmitting resin. For example, an ultraviolet (UV) curable resin is used. Can do.

The Fresnel lens unit 31 includes a Fresnel surface 31a that refracts transmitted light, and a rise surface 31b that has a predetermined angle with the optical axis P1 and is connected to an adjacent Fresnel surface.
The Fresnel surface 31a has a shape obtained by cutting a part of a lens surface, such as a spherical surface or an aspherical surface, by a substantially cylindrical surface rise surface 31b with the optical axis P1 as the center, according to the design conditions of the Fresnel lens portion 31. The
In this embodiment, when the Fresnel lens unit 31 is a projection lens used for the rear projection television 10, the image light projected from the focal position on the optical axis P1 is incident on the Fresnel lens sheet 30 at a position corresponding to the projection angle. In this case, the light is refracted by the Fresnel surface 31a to be emitted as light substantially parallel to the optical axis P1. That is, the curved surface of the spherical or aspherical convex lens is divided into an appropriate number of annular zones.

Next, the light diffusing lens array sheet 40 will be described.
As shown in FIG. 2, the light diffusing lens array sheet 40 has a diffusing lens portion 44, a sheet substrate 42, a light shielding portion 45, a transparent base material 47, and a light diffusing portion 52 layered in this order from the Fresnel lens sheet 30 side. It is the arrange | positioned flat member. The shape viewed from the optical axis direction is a substantially rectangular shape similar to that of the Fresnel lens sheet 30.

The diffusing lens unit 44 constitutes an incident surface of a lenticular lens sheet in which a plurality of cylindrical lenses 43 having a substantially semi-cylindrical shape are arranged substantially in parallel to each other and extend in the vertical direction (vertical direction, vertical direction in the drawing). ing.
With such a configuration, the image light emitted from the Fresnel lens sheet 30 is condensed and diffused in the horizontal direction (horizontal direction, vertical direction in the figure) of the screen to form striped light and then emitted toward the diffusion layer 52. It can be done.

  The light shielding part (BS = black stripe) 45 is a striped non-condensing part formed between the condensing positions of the cylindrical lenses 43 on the back side of the sheet substrate 42 on which the plurality of cylindrical lenses 43 are provided. This is a light absorption band provided in a stripe shape to shield light. An opening 46 through which the image light collected by the cylindrical lens 43 passes is formed between the light shielding portions 45 and is emitted as diffusion light toward the diffusion layer 52.

The transparent substrate 47 is for allowing the diffused light emitted from the opening 46 to enter the light diffusing portion 52 with a predetermined distance therebetween.
The light diffusing section 52 is configured by dispersing light diffusing fine particles in a base material. When the image light is incident on the light diffusion unit 52, the incident image light can be diffused in the vertical direction (vertical direction) of the screen.

The light diffusing section 52 can employ, for example, a plate-shaped or sheet-shaped light diffusing member having light diffusibility for diffusing diffused light transmitted through the transmission surface 46 in the left-right direction and the up-down direction. For example, it can be composed of a diffusion film in which a light diffusion material is dispersed. And it mounts | wears with the surface of the transparent base material 47 through a light-transmitting adhesion layer etc., for example.
Although not shown, the light diffusing section 52 also employs a transfer method in which a diffusing material is dispersed in a resin and transferred from a transfer sheet provided on a release sheet, or a coating method in which a diffusing material is dispersed in a resin is applied. Can do. And the light-diffusion part formed is about Haze 50-90%. In addition, it can be applied to each diffusion layer provided in any of the transmission screens of the present invention by appropriately adjusting the Haze value at the formation position.

  Next, the transmissive screen 22 according to the second embodiment of the present invention shown in FIG. 3 has substantially the same configuration as the transmissive screen 20 according to the first embodiment shown in FIG. A light diffusing portion 33, a transparent substrate 32, and a Fresnel lens 31 are sequentially arranged from the incident side of the image light, and the diffusing layer 33 and the Fresnel lens portion 31 are joined at the joining surfaces 38 and 37 of the transparent substrate 32. It is. The Fresnel lens portion 31 is opposed to the light diffusion lens array sheet 40.

The light diffusing section 33 of the Fresnel lens sheet 30 is the same as the light diffusing section 52 on the light diffusing lens array sheet 40 of the transmissive screen 20 according to the first embodiment shown in FIG. For diffusing light while transmitting, for example, a plate-like or sheet-like light diffusing member having light diffusibility can be adopted. For example, it can be composed of a diffusion film in which a light diffusion material is dispersed. Then, it is attached to the bonding surface 38 of the transparent substrate 32 via, for example, a light-transmitting adhesive layer.
The light diffusing unit 33 can also employ a transfer method in which a diffusing material is dispersed in a resin and transferred from a transfer sheet provided on a release sheet, or a coating method in which a diffusing material is dispersed in a resin. And if the diffusion layer to be formed is about 30 to 70% of Haze, it can be adopted.

Next, the operation of the rear projection television 10 of this embodiment will be described focusing on the operation of the transmission screen 22 of the second embodiment shown in FIG.
As shown in FIG. 1, the image 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 22. The light enters the diffusion layer 33 of the Fresnel lens sheet 30, is diffused, passes through the transparent substrate 32, and enters the Fresnel lens 31 from the bonding surface 37. When the image light reaches the lens surface 31a, the image light is refracted by the lens surface 31a and emitted from the Fresnel lens sheet 301 toward the lenticular lens sheet 40.

The image light incident on the light diffusing lens array sheet 40 is condensed in the left-right direction (horizontal direction) of the screen by the diffusing lens unit 44 and formed into a stripe shape, and then transmitted through the opening 46 and in the left-right direction of the screen. Diffused. Then, by being incident on the diffusion layer 52, it is diffused and emitted also in the vertical direction (vertical direction) of the screen.
For this reason, image 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 22 to the front surface side. It is possible to appreciate the image light within a predetermined viewing angle range.

As described above, in this embodiment, the diffusion degree of the diffused light emitted from the transmission screen 22 is a characteristic obtained by combining the light diffusion characteristics of the two light diffusion parts of the light diffusion part 33 and the light diffusion part 52. ing.
Therefore, three or more light diffusing parts can be provided, and the required degree of diffusion can be appropriately assigned to the light diffusing characteristics of each light diffusing part, and the degree of diffusion of each light diffusing part can be reduced, especially layered In the case of the light diffusion portion, it is possible to set the layer thickness to be thinner by reducing the diffusion degree. Thereby, the thickness of the transmission screen 22 can be reduced, and there is also an advantage that the thickness and weight can be reduced.

  From the above knowledge, the inventor of the present application, when each light diffusion part is separated with the transparent substrate 32 and the diffusion lens part 44 apart, the diffusion range is increased according to the optical path length of the separation part. Even if the light diffusing part has a relatively small light diffusing property, there is an advantage that the light diffusing action can be enhanced, and the light diffusing property becomes higher on the incident side, so that the degree of diffusion is reduced on the incident side. Can do. It has been found that the distance between the light diffusing portion 33 and the light diffusing portion 52 is preferably 2 mm or more and 4 mm or less because the image is blurred when it is separated more than necessary and scintillation occurs when it is too close.

Therefore, first, the thickness t from the lens apex of the Fresnel lens sheet 301 to the light diffusion portion is set to 1.85 mm (constant), and the thickness from the lens apex of the lenticular lens sheet to the light diffusion portion as the light diffusion lens array sheet 40. The transmission screen 22 shown in FIG. 3 in which T was variously set to 1.85 mm, 1.50 mm, 1.35 mm, and 0.8 mm was manufactured, and the occurrence state and resolution of the scintillation were measured and evaluated. The results are shown in the graph of FIG. 4. Scintillation decreases as the thickness of the lenticular lens sheet increases, while the resolution increases as the thickness of the lenticular lens sheet decreases, and the resolution increases as the thickness increases. The two are in a trade-off relationship so that That is, when the lenticular lens sheet is thin, the image quality is sharp, but the scintillation is conspicuous, and when the lenticular lens sheet is thick, the image quality is easily blurred but the scintillation is not conspicuous. When the thickness of the lenticular lens sheet can be balanced, that is, the scintillation is not conspicuous and the resolution is hardly lowered, the thickness is in the range of 1.20 mm to 1.50 mm. Moreover, it is preferable that the thickness of the light diffusion lens array sheet is 0.30 to 0.85 with respect to the thickness of the Fresnel lens sheet. More preferably, it is 0.60-0.85.
As described above, in the present embodiment, by making the lenticular lens sheet thin and the Fresnel lens sheet thick, it is possible to obtain a transmission screen that balances both in improving scintillation and improving resolution.

Further, as the Fresnel lens sheet 301 and the light diffusing lens array sheet 40, the light diffusing portions 33 and 52 of the lenticular lens sheet are formed on the transparent base material 47 by transferring from the transfer sheet provided on the release sheet by dispersing the diffusing material in the resin. In some cases, the light diffusing portions 33 and 57 are arranged at positions separated by the lens base material 32 and the transparent base material 47, respectively. Therefore, the scintillation can be reduced, but there is a problem in terms of resolution. Therefore, the thicknesses of the lens base material 32 and the transparent base material 47 laminated on the Fresnel lens sheet 301 and the lenticular lens sheet 40 are 1.85 mm, 1.50 mm, and 1.20 mm, respectively, and are transferred to the Fresnel lens sheet 301. When the thickness of the light diffusing portion 33 is 31 μm and the thickness of the light diffusing portion 52 by transfer to the lenticular lens sheet is 57 μm, the scintillation is visually observed (good ○, within the limit Δ, defective x) and brightness Variation (calculated from the screen where the scintillation was shot with the camera from the white screen display surface, the standard deviation was obtained from the result of good ○, within the limit △, defective ×), the resolution visually (good ○, within the limit △, Evaluation was carried out according to three stages of defective x). The results are shown in FIGS. 5 (1) to (3), and the comprehensive evaluation based on the results of (1) to (3) is shown in (4).
According to this, scintillation is (1) visually and (2) in the variation in brightness, the distance separated by the transparent base materials 32 and 47 is large, that is, the thicker the transparent base material, the better the evaluation, (3) In terms of resolution, the smaller the distance between the transparent substrates 32 and 47, that is, the thinner the transparent substrate, the better the evaluation. When the area where the scintillation and the resolution can be said to be relatively good or higher is raised, it can be said that the thickness of the lenticular lens sheet is preferably smaller than that of the Fresnel lens sheet as shown in (4).

A transmissive screen 23 according to a fourth embodiment of the present invention shown in FIG. 6 will be described.
In the transmissive screen 23, a diffusing material is mixed into the transparent base material 47 of the light diffusing lens array sheet 40 of the transmissive screen 22 of the second embodiment, and the diffusing function thereof is a light diffusing portion on the Fresnel lens sheet 302 side. 33, a light diffusing portion 53 that is smaller than the light diffusing portion 52 of the light diffusing wrench array sheet 40, that is, having a small degree of diffusion. Although not specified, a diffusion function can be similarly provided to the lens base material 32 and the lens part 31 of the Fresnel lens sheet 302 or the diffusion lens part 44 and the lens base material 42 of the light diffusion lens array sheet 40.

  According to this, video light incident on a projector with a small projection lens diameter represented by a liquid crystal projector or a light valve can be obtained without lowering the resolution or brightness by adding a small diffusion function to the configuration other than the light diffusion unit. The coherence in can be reduced.

A transmission screen 24 according to the fifth embodiment of the present invention shown in FIG. 7 will be described.
The transmissive screen 23 includes a light diffusing lens array sheet 40 of the transmissive screen 22 of the second embodiment, and (1) a lenticular lens sheet 401 formed by arranging a plurality of semi-cylindrical cylindrical lenses in parallel. (2) A plurality of lens array sheets 402 in which a plurality of semi-cylindrical cylindrical lenses are arranged in parallel, and the arrangement directions of the cylindrical lenses are orthogonal to each other and arranged in a light transmission direction, (3) a semi-cylindrical lens A lens unit in which a first lens array and a second lens array formed by arranging a plurality of cylindrical lenses in parallel are arranged and integrated on the same plane so that the length directions of the cylindrical lenses are orthogonal to each other. An arrayed lens array sheet 403 is provided.

  According to this, the image light collected by the Fresnel lens sheet 303 is diffused in the horizontal direction and further in the vertical direction, the viewing angle is expanded, the viewing angle is expanded in other directions, and the scintillation is reduced. Decrease in resolution and brightness can be prevented.

A transmission screen 25 according to a sixth embodiment of the present invention shown in FIGS. 8 (1) and (2) will be described.
The light diffusing portion 33 of the Fresnel lens sheet 304 or the light diffusing portion 52 of the light diffusing lens array sheet 40 is arranged in close contact (1) or (2) close to another member, the lens base 32 or the transparent base 47. It is a configuration.
According to this, the light diffusing portion can be formed independently without being in close contact or in an adhesive state.

A transmission screen 26 according to the seventh embodiment of the present invention shown in FIG. 9 will be described.
The outermost layer on the observation side of the light diffusing lens array sheet 40 is a hard coat layer that also serves as a protective layer for preventing scratches, an antireflection layer for preventing external light from being reflected, and antistatic for preventing dust from adhering to static electricity. Any one or more optical functional layers 55 such as a layer and a colored layer for improving contrast can be formed in the same layer or in multiple layers.
According to this, by providing various optical function layers in the outermost layer of the transmission type screen of the present invention, without affecting the effect of preventing scintillation reduction and resolution / brightness reduction, An effect can be added.

A transmission screen 27 according to the eighth embodiment of the present invention shown in FIG. 10 will be described.
On the observation side of the light diffusing lens array sheet 40, a translucent substrate 56 having one or more of the optical functional layers 55 as the outermost layer can be disposed on the observation side.
The translucent base material 56 is made of glass or a highly transparent resin, is a support substrate for the lenticular lens sheet 40, is disposed in the vicinity of the diffusion layer 52, and is positioned to limit deformation of the diffusion lens portion 44. It is a member. The diffused light emitted from the diffusing layer 52 in the vertical and horizontal directions can be emitted toward the front side of the transmissive screen 27.
According to this, the self-supporting of the Fresnel lens sheet and the light diffusing lens array sheet can be assisted or the strength of the transmission screen can be given, and further, the observation side of the transmission screen, that is, the appearance can be improved. it can.

The Fresnel lens sheet 30 may include a mat surface 32a (light diffusion portion) instead of the light diffusion portion 33 of the above-described embodiment.
The mat surface 32a has, for example, a surface roughness Rz (10-point average roughness Rz defined in JIS B 0601-1994) of 2 to 6 μm, and a glossiness (JIS Z 8741-1997) of 60 ° incidence is 60 or less. The set configuration can be adopted.
As a method for forming the mat surface 32a, for example, the embossing roll unevenness may be transferred to the surface of the transparent substrate 32, or the unevenness may be formed by sandblasting or the like. Further, a configuration may be adopted in which a surface diffusion film whose surface is processed with a matte surface is attached to the bonding surface 38 via, for example, an adhesive layer.
In this way, since the light diffusion portion can be formed thin, there is an advantage that the transmission screen can be thinned.

  Further, the surface diffusion surface or the interface diffusion surface may be provided on the light diffusion lens array side. For example, a mat surface similar to the mat surface 32a may be formed in place of the diffusion layer 52, or a PET film having one surface roughened in place of the transparent film 49 may be used.

  In the above description of the third embodiment, the light diffusing unit is described as having 1 or 2, but three or more light diffusing units may be provided as necessary. If possible, the light diffusion portions described above may be used in any combination in the transmission screen of the present invention within the scope of the technical idea of the present invention.

(1), (2) is a schematic cross-sectional explanatory drawing including the optical axis of the projection optical system for explaining the rear projection display according to the embodiment of the present invention. FIG. 2 is an explanatory cross-sectional view along the direction perpendicular to the paper surface in FIG. 1 for explaining the schematic configuration of the transmission screen according to the first embodiment of the present invention. It is sectional explanatory drawing for demonstrating schematic structure of the transmissive screen which concerns on the 2nd Example of this invention. It is a graph which shows the relationship between the scintillation in the thickness of the transmission type screen which concerns on the 3rd Example of this invention, and the resolution. (1) to (3) are tables showing the state of scintillation, luminance variation, and resolution when the thickness of the Fresnel lens sheet and the light diffusing lens array sheet is changed, and (4) is a table showing (1) to (1) to (3). It is a table | surface which shows comprehensive evaluation based on the result of (3). It is sectional explanatory drawing for demonstrating schematic structure of the transmission type screen which concerns on the 4th Example of this invention. It is a perspective explanatory view for explaining a schematic structure of a transmission screen according to a fifth embodiment of the present invention. (1) And (2) is sectional explanatory drawing for demonstrating schematic structure of the transmissive screen which concerns on the 6th Example of this invention. It is sectional explanatory drawing for demonstrating schematic structure of the transmission type screen which concerns on the 7th Example of this invention. It is sectional explanatory drawing for demonstrating schematic structure of the transmission type screen which concerns on the 8th Example of this invention.

Explanation of symbols

10, 60 Rear projection television (projection display)
12 Projector 20, 21, 22, 23, 24, 25, 26, 27 Transmission type screen 30, 301, 302 Fresnel lens sheet 31 Fresnel lens (Fresnel lens part)
31a Fresnel surface 31b Rise surfaces 32, 42 Lens member 32A Matte surface (light diffusion portion)
33, 52 Diffusion layer (light diffusion part)
40 Light diffusing lens array sheet 400, 401, 402 Lenticular lens sheet, lens array sheet 43 Cylindrical lens 44 Diffusing lens part 45 Light shielding part 46 Opening part 47 Transparent base material 48 Light transmitting base material P1 Optical axis P2 Center

Claims (11)

A Fresnel lens sheet that makes image light projected from the light source to the observation side substantially parallel light;
A light diffusing lens array sheet in which a plurality of lenses for diverging video light that has been made substantially parallel light by the Fresnel lens sheet;
Placed close together,
A light diffusing portion disposed in the optical path of the image light and diffusing the image light, at least on the observation side of the light diffusion lens array sheet;
A transmission type screen, wherein the thickness of the Fresnel lens sheet in the light transmission direction is larger than the thickness of the light diffusion lens array sheet in the light transmission direction.   The transmissive screen according to claim 1, further comprising a light diffusion portion on a light source side of the Fresnel lens sheet.   The transmission type according to any one of claims 1 to 3, wherein a thickness of the light diffusion lens array sheet is in a ratio of 0.30 to 0.85 with respect to a thickness of the Fresnel lens sheet. screen.   The configuration of the light diffusion lens array has at least a lens portion and a lens base material, a transparent base material, and a light diffusion portion, and the configuration of the Fresnel lens sheet has at least a lens portion, a lens base material, and a light diffusion portion. 4. The transmission type screen according to claim 1, wherein the reference object of the thickness in the transmission direction is configured to exclude the lens portion.   5. The transmissive screen according to claim 1, wherein a diffusion degree of the light diffusion portion is smaller on the Fresnel lens sheet side than on the light diffusion lens array sheet side.   The transmissive screen according to claim 1, wherein a diffusion function smaller than that of the light diffusion portion is given to any configuration other than the light diffusion portion.   The light diffusion lens array sheet is a lenticular lens sheet in which a plurality of semi-cylindrical cylindrical lenses are arranged in parallel, a plurality of semi-cylindrical cylindrical lenses are arranged in parallel, and the arrangement direction of the cylindrical lenses is orthogonal and light A plurality of lens array sheets arranged in the transmission direction, a first lens array in which a plurality of semi-cylindrical cylindrical lenses are arranged in parallel, and a second lens array are arranged in the longitudinal direction of the cylindrical lenses. The transmissive screen according to claim 1, wherein the transmission type screen is a lens array sheet in which lens portions arranged on the same plane so as to be orthogonal to each other and integrated are arranged.   The transmissive screen according to any one of claims 1 to 6, wherein the light diffusing portion is arranged in close contact with or close to another member.   2. The observation side outermost layer is formed by forming any one or more optical functional layers such as a hard coat layer, an antireflection layer, an antistatic layer, and a colored layer in the same layer or in multiple layers. Item 9. The transmissive screen according to any one of Items 8 to 9.   9. The translucent base material provided with one or more of the optical function layers on the observation side outermost layer is disposed on the observation side, and is defined in any one of claims 1 to 8. Transmission screen.   An image projected from the light source to the observation side using a projector having a small projection lens diameter, such as a liquid crystal projector or a light valve, provided with the transmission screen according to any one of claims 1 to 10. A rear projection type display characterized in that light is displayed as an image through the transmissive screen.

Images