JP2004133478A - Transmission screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission screen capable of preventing a flicker of an image such as a scintillation or the like by minimizing a decrease in gain and a decrease in resolution without using an additional device even when a projection tube having a small projection pupil is used. I do.
A transmissive screen 1 has an optical function of condensing or diffusing light, and has a lens sheet or an optical sheet having at least two diffusion layers 1A, 1B, and 1C separated in a light transmission direction as a whole. It has a seat. One of the two diffusion layers is provided on the light-entering surface of the lens sheet or optical sheet closest to the light source side, and the other is on the light-emitting side of the lens sheet or optical sheet closest to the observation side. Provide on the surface. Further, the diffusion layer closer to the light source side has a smaller degree of light diffusion than the diffusion layer closer to the observation side than this diffusion layer. Further, the type of the diffusing agent to be added differs between the diffusion layer near the light source side and the diffusion layer near the observation side.
[Selection diagram] Fig. 1

Description

The present invention relates to a transmissive screen mainly used for a rear projection type projector such as a video projector and a slide projector.

Conventionally, as this type of transmission screen, a transmission screen using a lenticular lens sheet based on a synthetic resin material such as polymethyl methacrylate alone or in combination with another lens sheet is known. In such a transmissive screen, image light is projected and observed by a light source such as a CRT.

In recent years, projection tubes with small projection pupils, such as liquid crystal projectors and light valves, have been used as light sources instead of CRTs. However, the conventional transmission screen has a problem that when such a projection tube having a small projection pupil is used, flickering of an image called scintillation or speckle appears.

Conventional methods for solving such a problem include a method of scanning the screen with a laser light source (see Patent Document 1), a method of vibrating the screen (see Non-Patent Document 1), and a lens sheet. And the like, a method of adding a large amount of a diffusing agent to water has been proposed.

However, in the above-described conventional technology, a change in the projector main body or an additional device is required to prevent flickering of an image such as scintillation, and when a large amount of a diffusing agent is added, a decrease in gain or unnecessary resolution is required. There is a problem that a decrease in the density occurs.
JP-A-5-173094 J. Opt. Soc. Am. Vol. 66, No. 11, Nov. 1976, “Speckle-free rear-projection screen using two close screens in slow relative motion”

The present invention has been made in view of such a point. Even when a projection tube having a small projection pupil is used, no additional device is required, and a decrease in gain and a decrease in resolution are minimized. It is an object of the present invention to provide a transmissive screen that can prevent flickering of an image such as scintillation while being left.

A first feature of the present invention is a transmissive screen provided with a lens sheet having an optical function of condensing or diffusing light, wherein the lens sheet is separated from each other via a non-diffusion portion, and has a diffusive property. It has at least two diffusion parts including fine particles, and the diffusion part closer to the light source side among the at least two diffusion parts has a smaller degree of light diffusion than the diffusion part closer to the observation side than this diffusion part. A transmission screen characterized by the following.

In the first aspect of the present invention, one of the at least two diffusing portions is provided on a light incident side surface of the lens sheet, and the other is provided on a light emitting side surface of the lens sheet. Is preferred. Further, it is preferable that the at least two diffusing portions are provided on the surface and inside of the lens sheet.

A second feature of the present invention includes a Fresnel lens sheet and a lenticular lens sheet, wherein each of the Fresnel lens sheet and the lenticular lens sheet has at least one diffusing portion containing diffusing fine particles, The sheet has a non-diffusion portion containing no diffusing fine particles, and the transmission screen including the Fresnel lens sheet and the lenticular lens sheet as a whole has a plurality of diffusion portions separated from each other via the non-diffusion portion. Wherein the diffusing portion of the Fresnel lens sheet disposed on the light incident surface side has a smaller degree of light diffusion than the diffusing portion of the lenticular lens sheet disposed on the observation side. It is a transmission screen.

Advantageous Effects of Invention According to the present invention, even when a projection tube having a small projection pupil is used, flickering of images such as scintillation is prevented without requiring an additional device and minimizing a decrease in gain and a decrease in resolution. can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 is a diagram showing a first embodiment of a transmission screen according to the present invention.

As shown in FIG. 1, the transmissive screen 1 is composed of a single lens sheet having a Fresnel lens, a lenticular lens, or the like formed on one or both surfaces, and has at least two in the light transmission direction (left-right direction in the drawing). Diffusion portions 1A and 1B are provided in a localized manner (separated). In the first embodiment, the diffusing portions 1A and 1B are provided on the light incident side surface (light incident surface) and the light exit side surface (light exit surface) of the lens sheet.

Here, the diffusing portions 1A and 1B are portions for giving a light diffusing action, and emboss treatment of a minute lens, a resin layer containing a diffusing agent (diffusible fine particles) such as glass beads or organic beads, or a surface of the minute lens. It can be easily formed by a general method such as.

The diffuser is not limited to the surface of the lens sheet, but may be provided inside the lens sheet like the diffuser 1C.

The diffusers 1A and 1B diffuse the light from the light source so as to eliminate the coherence of the light, so that problems such as scintillation and speckle can be solved. However, diffusing the light from the light source lowers the resolution, and when a large amount of a diffusing agent is added to a single diffusing portion as in the conventional technique, the gain is lowered and the image becomes very poor. Get dark.

According to the first embodiment of the present invention, the two diffusing portions 1A and 1B are separately provided on the lens sheet, so that the amount of the diffusing agent is smaller than the amount of the diffusing agent used in the case of a single diffusing portion. It is possible to weaken the intensity of scintillation etc. to the same extent with a diffusing agent, and use less diffusing agent, so it is possible to prevent a decrease in gain and prevent an unnecessary decrease in image brightness. it can.

In addition, since the two diffusing portions 1A and 1B are separately provided on the lens sheet, the amount of the diffusing agent added is reduced, so that the amount of stray light generated inside the diffusing portions 1A and 1B can be reduced. Unnecessary lowering of resolution such as image and ghost can be suppressed.

{Circle around (4)} By such a light diffusing action, moire generated due to mutual interference between the Fresnel lens, the lenticular lens, the pixel of the light source, and the like can be reduced.

It is preferable that the diffusing portions 1A and 1B are provided on the light incident side and light exit side surfaces of the lens sheet. This is because, by increasing the distance between the diffusion units 1A and 1B and eliminating the coherence of the light from the light source, the light diffusion effect of each of the diffusion units 1A and 1B is suppressed to a very weak level, and the intensity of scintillation and the like is reduced. This is because the image quality can be reduced, and the decrease in image brightness can be extremely reduced.

Also, it is preferable that the degree of light diffusion of the diffusing portion 1A near the light source side be smaller than that of the diffusing portion 1B near the observation side. This is because the intensity of scintillation and the like can be suppressed by preventing the unnecessary reduction in resolution by reducing the diffusion of light by the diffusion element on the light incident side.

The evaluation items such as scintillation and the like include, in addition to the strength of the scintillation and the like described above, roughness of a flickering motion (magnitude of the scintillation and the like (roughness)) generated when a moving image is displayed. Here, in order to suppress the strength of scintillation and the like, it is preferable to add a diffusing agent having a small difference in the refractive index from the substrate, while to suppress the size (roughness) of scintillation and the like, the average particle size It is preferable to add a diffusing agent having a small particle size.

For this reason, when only scintillation or the like is a problem, the difference in refractive index from the base material is small and the average particle size is small in both the diffusion section 1A near the light source side and the diffusion section 1B near the observation side. It is conceivable to add a diffusing agent. However, a diffusing agent having a small difference in refractive index from the base material or a diffusing agent having a small average particle diameter narrows the viewing angle, so that the diffusing portion 1A needs to be provided so as to eliminate both the problem of scintillation and the like and the problem of the viewing angle. It is preferable that the type of the diffusing agent to be added and the type of the diffusing agent added to the diffusing section 1B be different.

Specifically, as shown in a seventh embodiment to be described later, the difference in the refractive index between the diffusing agent added to the diffusion portion 1A near the light source side and the base material is added to the diffusion portion 1B near the observation side. It is preferable that the difference in refractive index between the diffusing agent and the substrate be smaller than that to be used, and that the average particle size of the diffusing agent added to the diffusing portion 1B close to the observation side be equal to or smaller than a predetermined particle size (for example, 15 μm). .

Various methods are known as methods for adjusting the degree of light diffusion. Specifically, for example, when embossing is performed, the size of the embossment may be changed, and when a diffusing agent is used, its particle size, refractive index, or addition amount may be changed. The relationship between the particle diameter and refractive index of the diffusing agent and the light diffusing action is described in, for example, Non-Patent Document 2 (J. Opt. Soc. Am.A Vol. 2, No. 12, Dec. 1985, “ Diffraction analysis of bulk diffusers for projection-screen applications ”).

Second Embodiment FIG. 2 is a view showing a transmission screen according to a second embodiment of the present invention.

As shown in FIG. 2, the transmission screen 2 includes a plurality of lens sheets or optical sheets 2-1, 2-2, 2-3,... Are provided with diffusion portions 2A, 2B, 2C,.

Note that the diffusion unit 2A is provided on the light-incident side surface (light-incident surface) of the lens sheet or the optical sheet 2-1 disposed closest to the light source side, and the diffusion unit 2B is disposed closest to the observation side. The light emitting surface (light emitting surface) of the disposed lens sheet or optical sheet 2-2 is provided, and the diffusing portion 2C is provided on the light incident surface (light incident surface) of the lens sheet or optical sheet 2-3. ing.

Here, as the lens sheet, a linear or circular Fresnel lens sheet, a lenticular lens sheet having a lenticular lens formed on one or both surfaces, a lens sheet formed by combining a Fresnel lens or a lenticular lens on each surface, or the like Is used.

パ ネ ル As the optical sheet, a panel made of a resin such as polymethyl methacrylate having both flat surfaces is used.

Note that the characteristics of the diffusion units 2A, 2B, 2C,... And the characteristics related to the mutual positional relationship of the diffusion units 2A, 2B, 2C, and the like are described with reference to the diffusion units 1A, 1B in the above-described first embodiment. , 1C, and a detailed description is omitted here.

Next, a specific embodiment of the transmission screen shown in FIGS. 1 and 2 will be described.

First Embodiment FIG. 3 is a view showing a first embodiment of a transmission screen according to the present invention. This first example corresponds to the first embodiment shown in FIG. 1, and two diffusion layers (diffusion portions) are separately provided on both surfaces of a single lens sheet.

That is, in the first embodiment, as shown in FIG. 3, the diffusion layers 10A and 10B are formed on the light entrance surface 11a and the light exit surface 11b of the lens sheet 11 made of polymethyl methacrylate and having a thickness of 5 mm, respectively. Screen 10 was produced. In addition, on the light entrance surface 11a, a diffusion layer 10A is formed by embossing the Fresnel lens portion located on the light entrance surface 11a, and on the light exit surface 11b, glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 are provided. Was dispersed in 15 parts by weight to form a diffusion layer 10B having a thickness of 500 μm. In this example, the following second to seventh examples and comparative examples, the amount (parts by weight) of the diffusing agent such as glass beads is a value based on 100 parts by weight of the base material into which the diffusing agent is mixed.

Here, as the base material of the lens sheet 11, an impact-resistant methacrylic resin (refractive index: 1.51) manufactured by Sumitomo Chemical Co., Ltd. was used. EMB20 manufactured by Toshiba Barotini was used as glass beads having an average particle diameter of 11 μm and a refractive index of 1.535.

映像 When the image was evaluated by projecting image light on the transmission screen 10 thus produced by an LCD projector, an image with weak scintillation and good resolution was observed.

Second Embodiment FIG. 4 is a view showing a second embodiment of the transmission screen according to the present invention. The second example corresponds to the second embodiment shown in FIG. 2, and two diffusion layers (diffusion portions) are separately provided on two lens sheets. One of the two diffusion layers is provided on the surface of the lens sheet (the light incident surface of the Fresnel lens sheet).

In other words, in the second embodiment, as shown in FIG. 4, a transmission type by combining a 2 mm thick Fresnel lens sheet 21 made of polymethyl methacrylate and a 1 mm thick lenticular lens sheet 22 made of polymethyl methacrylate. The screen 20 was produced. In the Fresnel lens sheet 21, a 150 μm-thick diffusion layer 20A in which 7.0 parts by weight of organic beads having an average particle diameter of 12 μm and a refractive index of 1.59 were dispersed was formed on the light incident surface 21a. The lenticular lens sheet 22 (diffusion layer 20B) was uniformly mixed with 0.75 parts by weight of organic beads having an average particle diameter of 12 μm and a refractive index of 1.59.

Here, as the base material of the Fresnel lens sheet 21 and the lenticular lens sheet 22, an impact-resistant methacrylic resin (refractive index 1.51) manufactured by Sumitomo Chemical Co., Ltd. was used. As organic beads having an average particle diameter of 12 μm and a refractive index of 1.59, PB3011 (styrene beads) manufactured by Sumitomo Chemical Co., Ltd. was used.

When the image was evaluated by projecting image light on the transmission screen 20 produced in this manner by an LCD projector, an image with weak scintillation and good resolution was observed.

Third Embodiment FIG. 5 is a view showing a third embodiment of the transmission screen according to the present invention. The third example corresponds to the second embodiment shown in FIG. 2, and two diffusion layers (diffusion portions) are separately provided on three lens sheets and an optical sheet. One of the two diffusion layers was provided on the surface of the lens sheet (the Fresnel lens sheet light incident surface) located closest to the light source side, and the other was located closest to the observation side. It is provided on the surface of the optical sheet (the entire panel light incident surface).

That is, in the third embodiment, as shown in FIG. 5, a Fresnel lens sheet 31 made of polymethyl methacrylate and having a thickness of 2 mm, an entire panel 32 made of polymethyl methacrylate having a thickness of 2 mm, and a Fresnel lens sheet 31 A transmissive screen 30 was fabricated by combining with a lenticular lens sheet 33 having a thickness of 1 mm and not including a diffusing agent made of polymethyl methacrylate, disposed between the panel 32 and the panel 32. Of these, the Fresnel lens sheet 31 was formed on its light incident surface 31a with a diffusion layer 30A having a thickness of 150 μm in which 45 parts by weight of glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 were dispersed. Further, on the entire surface panel 32, a 150 μm-thick diffusion layer 30B in which 45 parts by weight of glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 were dispersed was formed on the light incident surface 32a.

Here, as the base material of the Fresnel lens sheet 31, the entire panel 32 and the lenticular lens sheet 33, an impact-resistant methacrylic resin (refractive index 1.51) manufactured by Sumitomo Chemical Co., Ltd. was used. EMB20 manufactured by Toshiba Barotini was used as glass beads having an average particle diameter of 11 μm and a refractive index of 1.535.

映像 When the image was evaluated by projecting image light on the transmission screen 30 produced in this manner by an LCD projector, an image with weak scintillation and good resolution was observed.

Fourth Embodiment FIG. 6 is a view showing a fourth embodiment of the transmission screen according to the present invention. The fourth example corresponds to the second embodiment shown in FIG. 2, and two diffusion layers (diffusion portions) are separately provided on two lens sheets. One of the two diffusion layers was provided on the surface of the lens sheet (the Fresnel lens sheet light incident surface) located closest to the light source side, and the other was located closest to the observation side. It is provided inside the lens sheet (inside the lenticular lens sheet). Further, of the two diffusion layers, the diffusion layer closer to the light source side has a smaller degree of light diffusion than the diffusion layer closer to the observation side than this diffusion layer.

That is, in the fourth embodiment, as shown in FIG. 6, a Fresnel lens sheet 41 made of polymethyl methacrylate and having a thickness of 2 mm, and transparent lenses 42b formed on both surfaces of a film 42a made of polymethyl methacrylate and having a thickness of 200 μm. The transmissive screen 40 was produced by combining the lenticular lens sheet 42 thus obtained. In the Fresnel lens sheet 41, a diffusion layer 40A having a thickness of 100 μm was formed by dispersing 35 parts by weight of glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 on the light incident surface 41a. Further, 10.0 parts by weight of organic beads having an average particle diameter of 12 μm and a refractive index of 1.59 were uniformly mixed into the film 42a (diffusion layer 40B) of the lenticular lens sheet 42.

Here, as the base material of the Fresnel lens sheet 41, an impact-resistant methacrylic resin (refractive index 1.51) manufactured by Sumitomo Chemical Co., Ltd. was used. EMB20 manufactured by Toshiba Barotini was used as glass beads having an average particle diameter of 11 μm and a refractive index of 1.535. Further, as organic beads having an average particle diameter of 12 μm and a refractive index of 1.59, PB3011 (styrene beads) manufactured by Sumitomo Chemical Co., Ltd. was used. The lenticular lens sheet 42 covers the UV (ultraviolet) curable resin or the EB (electron beam) curable resin poured into the mold having the reverse shape of the transparent lens 42b, and covers the film 42a with the UV curable resin or the EB. Molding was performed by irradiating the curable resin with ultraviolet rays or electron beams.

(4) When the image was evaluated by projecting image light on the transmission screen 40 produced in this manner by an LCD projector, an image with weak scintillation and good resolution was observed.

Fifth Embodiment FIG. 7 is a view showing a fifth embodiment of the transmission screen according to the present invention. The fifth example corresponds to the second embodiment shown in FIG. 2, and two diffusion layers (diffusion portions) are separately provided on two lens sheets. One of the two diffusion layers was provided on the surface of the lens sheet (the Fresnel lens sheet light incident surface) located closest to the light source side, and the other was located closest to the observation side. It is provided on the surface of the lens sheet (the lenticular lens sheet light emitting surface). Further, of the two diffusion layers, the diffusion layer closer to the light source side has a smaller degree of light diffusion than the diffusion layer closer to the observation side than this diffusion layer.

That is, in the fifth embodiment, as shown in FIG. 7, a 2 mm thick Fresnel lens sheet 51 made of polymethyl methacrylate and a 1 mm thick lenticular lens sheet 52 made of polymethyl methacrylate are combined. 50 were produced. In the Fresnel lens sheet 51, a diffusion layer 50A having a thickness of 100 μm was formed by dispersing 35 parts by weight of glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 on the light incident surface 51a. In the lenticular lens sheet 52, a diffusion layer 50B having a thickness of 100 μm was formed by dispersing 12.0 parts by weight of organic beads having an average particle diameter of 12 μm and a refractive index of 1.59 on the light exit surface 52b. Here, as a base material of the Fresnel lens sheet 51 and the lenticular lens sheet 52, an impact-resistant methacrylic resin (refractive index: 1.51) manufactured by Sumitomo Chemical Co., Ltd. was used. EMB20 manufactured by Toshiba Barotini was used as glass beads having an average particle diameter of 11 μm and a refractive index of 1.535. Further, as organic beads having an average particle diameter of 12 μm and a refractive index of 1.59, PB3011 (styrene beads) manufactured by Sumitomo Chemical Co., Ltd. was used.

(4) When the image was evaluated by projecting image light on the transmission screen 50 produced in this manner by an LCD projector, an image with weak scintillation and good resolution was observed.

Sixth Embodiment FIG. 8 is a view showing a sixth embodiment of the transmission screen according to the present invention. The sixth embodiment corresponds to the second embodiment shown in FIG. 2, and three diffusion layers (diffusion portions) are provided separately on three lens sheets and optical sheets. Note that the three diffusion layers are provided on the surface (light incident surface) of the lens sheet or the optical sheet, respectively.

That is, in the sixth embodiment, as shown in FIG. 8, a 2 mm thick Fresnel lens sheet 61 made of polymethyl methacrylate, a 2 mm thick full-surface panel 62 made of polymethyl methacrylate, and a Fresnel lens sheet 61 A transmissive screen 60 was fabricated by combining with a lenticular lens sheet 63 made of polymethyl methacrylate and having a thickness of 1 mm disposed between the panel and the panel 62. In the Fresnel lens sheet 61, a 100 μm-thick diffusion layer 60A in which 3.5 parts by weight of glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 were dispersed on the light incident surface 61a was formed. In addition, a diffusion layer 60B having a thickness of 100 μm in which 3.5 parts by weight of glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 were dispersed on the light incident surface 62a of the entire panel 62 was formed. Further, on the lenticular lens sheet 63, a 300 μm-thick diffusion layer 60C in which 5.0 parts by weight of organic beads having an average particle diameter of 30 μm and a refractive index of 1.49 were dispersed was formed on the light incident surface 63a.

Here, as a base material of the Fresnel lens sheet 61, the entire panel 62, and the lenticular lens sheet 63, an impact-resistant methacrylic resin (refractive index 1.51) manufactured by Sumitomo Chemical Co., Ltd. was used. EMB20 manufactured by Toshiba Barotini was used as glass beads having an average particle diameter of 11 μm and a refractive index of 1.535. Further, as organic beads having an average particle diameter of 30 μm and a refractive index of 1.49, XC01 (acrylic beads) manufactured by Sumitomo Chemical Co., Ltd. was used.

(4) When the image was evaluated by projecting image light on the transmission screen 60 produced in this manner by an LCD projector, an image with weak scintillation and good resolution was observed.

Seventh Embodiment FIGS. 9A and 9B are views showing a transmission screen according to a seventh embodiment of the present invention. The seventh example corresponds to the second embodiment shown in FIG. 2, and two diffusion layers (diffusion portions) are separately provided on two lens sheets. Further, of the two diffusion layers, the type (refractive index and average particle size) of the diffusing agent is different between the diffusion layer closer to the light source side and the diffusion layer closer to the observation side.

That is, in the seventh embodiment, as shown in FIGS. 9A and 9B, Fresnel lens sheets 71 and 81 made of polymethyl methacrylate, and lenticular lens sheets 72 and 82 made of polymethyl methacrylate and having a thickness of 1 mm. Were combined to produce transmission screens 70 and 80, respectively. As shown in FIGS. 9A and 9B, the transmissive screens 70 and 80 have substantially the same shape and structure except that the structure of the Fresnel lens sheets 71 and 81 is different.

Here, as a base material of the Fresnel lens sheets 71 and 81, a material extruded using an impact-resistant methacrylic resin (refractive index 1.51) manufactured by Sumitomo Chemical Co., Ltd. is used, and one surface thereof is used. The Fresnel lens portions 71 and 81 were obtained by forming a Fresnel lens portion by a UV curing method using a UV curable resin containing no diffusing agent. In FIGS. 9A and 9B, the boundary between the base material and the Fresnel lens portion made of the UV curable resin is not shown.

Note that the Fresnel lens sheet 71 shown in FIG. 9A uses a single-layer (diffusion layer 70A) base material in which a diffusing agent having a predetermined average particle size and refractive index is uniformly mixed. Is a lens sheet having a Fresnel lens portion formed on the surface thereof. In addition, a Fresnel lens sheet 81 shown in FIG. 9B has a light incident surface 81a formed with a diffusion layer 80A in which a diffusing agent having a predetermined average particle size and a refractive index is dispersed by a coextrusion molding method or the like. This is a lens sheet in which a Fresnel lens portion is formed on one surface using a base material of a layer.

The diffusing agent added to the diffusion layers 70A and 80A includes (1) acrylic beads having an average particle diameter of 30 μm and a refractive index of 1.49 (XC01 manufactured by Sumitomo Chemical Co., Ltd.), and (2) an average particle diameter of 11 μm. Acrylic beads having a refractive index of 1.49 (MBX, manufactured by Sekisui Chemical Co., Ltd.), (3) glass beads having an average particle diameter of 17 μm and a refractive index of 1.535 (EGB210 manufactured by Toshiba Barotini), (4) average particle diameter of 12 μm, refraction Any one of styrene beads having a ratio of 1.59 (PB3011 manufactured by Sumitomo Chemical Co., Ltd.) was used.

　なお上記表１において、添加剤の種類（例えば「ＸＣ０１」）の右側に付された数字（例えば「２．５ｔ」）はフレネルレンズシート７１，８１の基材の厚さ（ｍｍ）を示し、これにＵＶ硬化性樹脂により形成したフレネルレンズ部の厚さ０．２ｍｍを加えた厚さがフレネルレンズシート７１，８１の厚さとなる。また、このような基材の厚さ（ｍｍ）を表す数字（例えば「１．８ｔ」）の右側に付された「（２）」は、その添加剤が添加されるフレネルレンズシートの基材が２層構造（図９（ｂ）に示す構造）となっていることを表している。なお、拡散剤の濃度の単位（Ｐ）は基材であるポリメチルメタクリレート１００重量部（１００ｇ）に混入されている拡散剤の重量部（ｇ数）を示している。 Here, these diffusing agents (1) to (4) were added to the diffusion layers 70A, 80A of the Fresnel lens sheets 71, 81 in the manner shown in Table 1 below.

In Table 1, the number (for example, "2.5t") attached to the right side of the type of the additive (for example, "XC01") indicates the thickness (mm) of the base material of the Fresnel lens sheets 71, 81, The thickness of the Fresnel lens sheets 71 and 81 is obtained by adding 0.2 mm to the thickness of the Fresnel lens portion formed of the UV curable resin. Further, “(2)” attached to the right side of a number (for example, “1.8 t”) representing the thickness (mm) of such a substrate is the substrate of the Fresnel lens sheet to which the additive is added. Indicates a two-layer structure (the structure shown in FIG. 9B). The unit (P) of the concentration of the diffusing agent indicates the weight part (g number) of the diffusing agent mixed in 100 parts by weight (100 g) of polymethyl methacrylate as the base material.

On the other hand, as the base material of the lenticular lens sheets 72 and 82, similarly to the Fresnel lens sheets 71 and 81, an impact-resistant methacrylic resin (refractive index 1.51) manufactured by Sumitomo Chemical Co., Ltd. The entire lens sheets 72 and 82 were formed by an extrusion method. As shown in FIGS. 9A and 9B, the lenticular lenses 72 and 82 have a 600 μm-thick diffusion layer in which a diffusing agent having a predetermined average particle diameter and a predetermined refractive index is dispersed on the light emitting surfaces 72 b and 82 b. 70B and 80B were formed.

The diffusing agent added to the diffusion layers 70B and 80B includes (1) glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 (EMB20 manufactured by Toshiba Barotini),
(2) Glass beads having an average particle size of 17 μm and a refractive index of 1.535 (EGB210 manufactured by Toshiba Barotini), and (3) acrylic beads having an average particle size of 30 μm and a refractive index of 1.49 (XC01 manufactured by Sumitomo Chemical Co., Ltd.) (XC01 + EGB-1) obtained by mixing the above with EGB210 made by Toshiba Barotini in a ratio of 6: 1, and (4) XC01 made by Sumitomo Chemical Co., Ltd. and EGB210 made by Toshiba Barotini 2: 3. (XC01 + EGB-2).

Here, the diffusing agents (1) to (4) were added to the diffusion layers 70B, 80B of the lenticular lens sheets 72, 82 in the following manner. That is, among the diffusing agents (1) to (4), “XC01 + EGB−” is obtained by mixing the XC01 manufactured by Sumitomo Chemical Co., Ltd. with the EGB210 manufactured by Toshiba Barotini at a ratio of 6: 1. With reference to "1", the concentration of EGB210 contained in "XC01 + EGB-1" was set to 2.0P. The concentrations of the other diffusing agents (1), (2) and (4) were obtained by combining a lenticular lens sheet containing the diffusing agent with a Fresnel lens sheet of “XC01@2.5t” shown in Table 1 above. The gain of the transmissive screen is substantially the same as the gain of the transmissive screen obtained by combining the lenticular lens of “XC01 + EGB-1” and the Fresnel lens sheet of “XC01 2.5t” (within ± 0.2). Set to.

　上記表２の評価結果から、シンチレーション等の強さおよび大きさ（粗さ）ともに評価の高い組み合わせは、光源側に近いフレネルレンズシート（ＦＬ）に添加する拡散剤として平均粒径３０μｍ、屈折率１．４９のアクリルビーズ（住友化学工業（株）製ＸＣ０１）を用い、観察側に近いレンチキュラーレンズシート（ＬＬ）に添加する拡散剤として平均粒径１１μｍ、屈折率１．５３５のガラスビーズ（東芝バロティーニ社製ＥＭＢ２０）を用いたものであることが確かめられた。 The above-described various lenticular lenses 72 and 82 and the lenticular lens sheets 72 and 82 are combined in a frame (not shown) to produce transmission screens 70 and 80, and each of the produced screens 70 and 80 is produced. When an image was evaluated by projecting a white screen on the transmission screens 70 and 80 using an LCD projector, the results shown in Table 2 below were obtained for the strength and size (roughness) of scintillation and the like. . Here, the size (roughness) of scintillation and the like was evaluated by the flickering roughness and the like when the observer's eyes were moved. In addition, the best evaluation of the strength and size of scintillation and the like was “5”, and the worst evaluation was “0”.

From the evaluation results in Table 2 above, the combination having a high evaluation for both the strength and the size (roughness) of scintillation and the like is a diffusing agent added to the Fresnel lens sheet (FL) close to the light source side, having an average particle size of 30 μm and a refractive index. Using acrylic beads of 1.49 (XC01 manufactured by Sumitomo Chemical Co., Ltd.), glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 (Toshiba) as a diffusing agent to be added to a lenticular lens sheet (LL) near the observation side. It was confirmed that EMB20 manufactured by Barotini was used.

Also, from the evaluation results in Table 2 above, the smaller the difference between the refractive index of the diffusing agent added to the Fresnel lens sheet (FL) closer to the light source and the refractive index (1.51) of the substrate, the stronger the scintillation and the like. It was confirmed that the size and the size (roughness) tended to be smaller (for example, see the difference in evaluation between “MBX 1.8t” and “PB3011 1.8t” having substantially the same average particle size). Furthermore, it was confirmed that the smaller the average particle size of the diffusing agent added to the lenticular lens sheet (LL) near the observation side, the smaller the size (roughness) of scintillation and the like (for example, the refractive index is reduced). (See difference in rating between equal "EGB" and "EMB"). In addition, regarding the average particle size of the diffusing agent added to the lenticular lens sheet (LL), scintillation between EGB 210 (average particle size 17 μm) and EMB 20 (average particle size 11 μm), particularly near the average particle size 15 μm. A significant improvement in size (roughness) was observed.

From the evaluation results in Table 2 above, it was also confirmed that as the thickness of the Fresnel lens sheet (FL) is larger, the strength and size (roughness) of scintillation are smaller in the two layers rather than the single layer. Was done.

Comparative Example FIG. 10 is a diagram showing a comparative example of the transmission screen.

As shown in FIG. 10, in this comparative example, a 2 mm thick Fresnel lens sheet 91 containing no diffusing agent made of polymethyl methacrylate and a 1 mm thick lenticular lens sheet 92 made of polymethyl methacrylate were transmitted. A mold screen 70 was produced. 5 parts by weight of glass beads having an average particle diameter of 11 μm and a refractive index of 1.535 were uniformly mixed into the lenticular lens sheet 72 (diffusion layer 90 B).

Here, as the base material of the Fresnel lens sheet 91 and the lenticular lens sheet 92, an impact-resistant methacrylic resin (refractive index 1.51) manufactured by Sumitomo Chemical Co., Ltd. was used. EMB20 manufactured by Toshiba Barotini was used as glass beads having an average particle diameter of 11 μm and a refractive index of 1.535.

(4) When the image was evaluated by projecting image light on the transmission screen 90 thus produced by an LCD projector, it was observed that the image flicker was strong and the image quality was deteriorated.

As described above, according to the present invention, at least two diffusing portions are provided separately on one or a plurality of lens sheets or optical sheets, so that the amount of diffusing agent used in the case of a single diffusing portion is increased. It is possible to reduce the intensity of scintillation to a similar extent with a smaller amount of diffusing agent. Further, by making the types of the diffusing agent used in the two diffusing units different, it is possible to reduce the size (roughness) of the scintillation and the like as well as the strength of the scintillation and the like. Therefore, it is possible to effectively reduce the flicker of the image such as the scintillation while suppressing the decrease in the resolution and the decrease in the brightness of the image.

FIG. 1 is a view showing a first embodiment of a transmission screen according to the present invention. FIG. 2 is a view showing a second embodiment of the transmission screen according to the present invention. FIG. 3 is a view showing a first embodiment of the transmission screen according to the present invention. FIG. 4 is a view showing a second embodiment of the transmission screen according to the present invention. FIG. 5 is a view showing a third embodiment of the transmission screen according to the present invention. FIG. 6 is a view showing a fourth embodiment of the transmission screen according to the present invention. FIG. 7 is a view showing a fifth embodiment of the transmission screen according to the present invention. FIG. 8 is a view showing a sixth embodiment of the transmission screen according to the present invention. FIGS. 9A and 9B are views showing a seventh embodiment of the transmission screen according to the present invention. FIG. 10 is a diagram showing a comparative example of the transmission screen.

Explanation of reference numerals

1, 2 transmissive screen 1A, 1B, 1C Diffusion unit 2A, 2B, 2C Diffusion unit

Claims (4)

In a transmission screen provided with a lens sheet having an optical function such as light focusing or diffusion,
The lens sheet has at least two diffusion portions including diffusing fine particles, which are separated from each other via a non-diffusion portion,
A transmissive screen characterized in that, of the at least two diffusing portions, a diffusing portion closer to the light source side has a smaller degree of light diffusion than a diffusing portion closer to the observation side than the diffusing portion. 2. The lens sheet according to claim 1, wherein one of the at least two diffusing portions is provided on a light incident side surface of the lens sheet, and the other is provided on a light emitting side surface of the lens sheet. Transmission screen. The transmission screen according to claim 1, wherein the at least two diffusion portions are provided on a surface and inside of the lens sheet. Fresnel lens sheet,
With a lenticular lens sheet,
The Fresnel lens sheet and the lenticular lens sheet each have at least one diffusing portion containing diffusing fine particles, the lenticular lens sheet has a non-diffusing portion containing no diffusing fine particles, and the Fresnel lens sheet and the The transmission screen including the lenticular lens sheet as a whole has a plurality of diffusion portions separated from each other via the non-diffusion portion, and the diffusion portion of the Fresnel lens sheet arranged on the light incident surface side, A transmissive screen, wherein the degree of light diffusion is smaller than that of the diffusing portion of the lenticular lens sheet arranged on the observation side.

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