JP5070377B2 - Light diffusion sheet, screen sheet provided with light diffusion sheet, and video system - Google Patents

Description

The present invention relates to a light diffusing sheet used in a large-sized image device or the like, in particular, a light diffusing sheet used in an image device having a narrow viewing angle, a screen sheet provided with the light diffusing sheet , and an image system .

  Large-scale video devices such as display devices using optical fibers are intended to provide a wide range of images in the horizontal and vertical directions, but the video device alone has its original purpose due to the directivity of light by the video projection system of the device. Cannot be achieved. Therefore, a viewing angle is usually obtained by installing a light diffusion sheet on the display surface of the video apparatus.

  A conventional light diffusion sheet that enables visual recognition of a wide range of images has been reported in a document entitled “New Development of Transparent Resin and Its Optical Application (Chapter 7: Optical Functional Film)”. As described in this document, a conventional light diffusing sheet is a glass having a light diffusing function in the resin surface or in the resin surface, based on a highly light transmissive resin based on polypropylene or polyester. Fine particles such as beads are dispersed (hereinafter referred to as “optical film structure”). However, a conventional light diffusion sheet composed of light diffusion functional particles and a highly light-transmitting resin cannot obtain both sufficient viewing angle and luminance characteristics.

  In addition to the film, Patent Document 1 discloses a method in which a light diffusing sheet is formed by regularly arranging light transmissive strands such as rod lenses and plastic optical fibers on a film. A method of forming a light diffusion sheet by regularly arranging the light diffusion sheet is described in Patent Document 2, and a method of forming a light diffusion sheet by regularly arranging rod lenses and light transmissive strands in a woven structure is described in Patent Document 3. Has been.

Japanese Utility Model Publication No.59-121647 JP-A 64-76041 Japanese Utility Model Publication No. 1-166335 "New development of transparent resin and its optical application (Chapter 7: Optical functional film)" Type: Survey report Distributor: Toray Research Center, Inc.

As described in Patent Documents 1 to 3, a wide viewing angle can be realized by regularly arranging rod lenses or light transmissive strands. However, each of Patent Documents 1 to 3 has the following problems.
That is, the method of Patent Document 1 is unproductive and cannot be realized in practice. More specifically, if the linearity of the light-transmitting strands is poor, moire occurs in the projected image and the image quality deteriorates. It is requested with high accuracy. However, it is actually difficult to arrange and fix the light-transmitting strands straight on the film substrate as in Patent Document 1, and thus a light diffusion sheet that sufficiently meets the above requirements cannot be obtained.

  Further, the method of Patent Document 2 has a configuration in which two yarns are interposed between rod lenses because of the principle of knitting structure, and it is difficult to arrange the rod lenses without any gaps. Thus, when two yarns are interposed between the light transmissive strands, the distance between the rod lenses is greatly widened, the light shielding area is also increased, the light transmittance is lowered, and the image quality is lowered.

  The method of Patent Document 3 is the most productive compared to Patent Documents 1 and 2 above. However, when the light-transmitting strand is used for warp yarn, the light-transmitting strand is always bent from the principle of the weaving process, and moire is generated due to the bending, so that it is not suitable as a light diffusion sheet.

An object of the present invention is to solve the above-mentioned problems of the prior art, maintain a high light transmittance, have a wide viewing angle, and can obtain a clear image without moire , A screen sheet provided with a diffusion sheet and an image system are provided.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have arranged light-transmitting strands having a lens effect as linear wefts of a fabric without being bent linearly without any gaps. And a wide viewing angle was found, and the present invention was completed. The specific configuration of the present invention is as follows.

The invention according to claim 1 is a light diffusion sheet composed of a first fiber having a light-transmitting circular or pseudo-circular cross-sectional shape, and a woven fabric woven using only the second fiber , It said second fibers thinner than said first fibers, using said first fibers as weft, and using the second fiber as a warp, the weft is parallel to each other, without bending, and substantially close It is characterized by having a woven structure structure arranged in this manner .

  As described above, by using the first light-transmitting fiber as the weft, a weave structure in which the weft is arranged almost closely without bending is obtained. Therefore, when a light diffusion sheet having such a woven structure is installed on the screen of a large video apparatus, a clear image with a wide viewing angle and no moire can be obtained.

  Further, in the case of the light diffusion sheet having a woven structure as in the present invention, the light-transmitting wefts each exhibit a lens effect and diffuse and emit incident light. It has almost the same light diffusibility. In addition, since the light diffusing sheet of the present invention uses a light-transmitting weft, the light transmittance is higher than that of a conventional light diffusing sheet having an optical film structure. This is because a conventional light diffusion sheet having an optical film structure is formed by dispersing fine particles such as glass beads having a light diffusion function in the resin or on the resin surface, using a resin having a high light transmittance as a base material. Therefore, there are two light transmitting members, that is, a base material and fine particles having a light diffusion function. On the other hand, in the light diffusing sheet of the present invention, the light transmissive member is only a light transmissive weft. As described above, the light diffusion sheet of the present invention has a high light diffusibility substantially equal to that of the light diffusion sheet of the conventional optical film structure, and has a wide viewing angle characteristic by having a high light transmittance. . In other words, even if the angle is gradually increased from the front of the image, the decrease in luminance gradually changes, and a clear image can be recognized in a wide range of angular positions.

The invention according to claim 2 is the light diffusing sheet according to claim 1, wherein the second fiber has a diameter ratio of 0.2 or less than the first fiber .

The invention described in claim 3 is a screen sheet, wherein the light diffusion sheet according to claim 1 or 2 is sandwiched by a film or an acrylic plate in a state where tension is applied to the warp yarn and the weft yarn, and the planarity is improved. The light diffusion sheet held is affixed to a screen substrate .

If it is the screen sheet of the said structure, the planar state of a light-diffusion sheet is hold | maintained. As a result, the weft yarn is not bent and a clear image free from moire is obtained.

The invention according to claim 4 is the screen sheet according to claim 3, wherein the screen substrate is configured by connecting a plurality of block bodies, and the light diffusion sheet that maintains the planarity is the screen sheet. It is characterized in that each block body is configured by being attached to a screen substrate .

The invention described in claim 5 is a video system comprising a video display source configured by arranging a large number of video display units at a predetermined pitch, and a screen sheet provided on the front side of the video display source. The screen sheet wefts a first fiber of two kinds of fibers, a first fiber having a light-transmitting circular or pseudo-circular cross-sectional shape and a second fiber thinner than the first fiber. A light diffusing sheet composed of a woven fabric in which the second fibers are used as warp yarns, and the warp yarns and the weft yarns are woven in a mesh shape in a state where a predetermined number of the warp yarns and the weft yarns are aligned, and the periphery of the light diffusion sheet and a frame body for fixing the parts, the light diffusion sheet, at the intersection of warp and weft cross each other, weft threads parallel to each other, without bending, is and substantially closely arranged Rutotomoni, intersection portions Interval has a substantially equal manner braided weave structure with a predetermined pitch of the image display alone, the light diffusion sheet, and characterized in that the cross section is disposed so as to cover the image display alone To do.

Light diffusing sheet of the above configuration, since the warp and weft and a weave structure having no bend at the intersection of intersecting, such cross section Film image display alone (e.g., if the video system LED video device, one In this case , a clear image without moire can be obtained.

According to the present invention, it is possible to realize the light diffusion sheet for a large imaging apparatus capable of realizing a wide sharp image viewing angle, the screen sheet and video systems, including the same.

  Hereinafter, the light diffusion sheet according to the present invention and a screen sheet provided with the light diffusion sheet will be described in detail based on the embodiments. Note that the present invention is not limited to the following embodiments.

(Embodiment 1)
1 is a perspective view of a light diffusion sheet according to Embodiment 1, FIG. 2 is an overall configuration diagram of a video apparatus using the light diffusion sheet according to Embodiment 1, and FIG. 3 is a cross-sectional view of a screen in the video apparatus. 4 is a front view of a screen in the video apparatus, and FIG. 5 is a partially enlarged view of FIG.
The image device 1 in which the light diffusion sheet according to the first embodiment is used is an optical fiber image device, and generally includes an image projector 2, an image input surface 3, and an optical fiber group 4 as shown in FIG. The image output surface 5 is provided. The image projector 2 outputs an image from a TV broadcast receiver, a video tape playback device, a personal computer or the like.

The image output surface 5 is formed on one surface side of the screen substrate 6. On the image output surface 5, as shown in FIG. 4, a plurality of video display units (hereinafter also referred to as pixels) 7 are arranged according to a predetermined arrangement pattern. Specifically, a pixel column in which a predetermined number of video display units 7 are arranged in a line along a specific direction (hereinafter referred to as “horizontal direction”) X is defined as a direction orthogonal to the horizontal direction X (hereinafter “vertical”). It is called “direction.”) A predetermined number is arranged in Y.
Furthermore, the image display unit 7 is constituted by the end portions of a predetermined number of optical fibers 8 (see FIG. 2). In the simplest configuration, the end of one optical fiber 8 forms one pixel, but the end of a plurality of optical fibers 8 may be bundled and arranged to form one pixel. For example, when one pixel is configured by arranging the ends of a plurality of optical fibers 8 in a matrix, halftone display is realized by appropriately selecting the number and position of the optical fibers 8 that output light. be able to. In the following description, the case where the end of one optical fiber 8 constitutes one video display unit 7 will be described as an example.

  Each one end of the optical fiber group 4 constitutes a video display unit 7 and is arranged vertically and horizontally to form an image output surface 5. In the present embodiment, the diameter of the optical fiber 8 is 0.75 mm, and therefore the diameter of the image display unit 7 is 0.75 mm. Further, the pitch P (see FIG. 5) of the video display unit 7 is 4 mm. Of course, it is not limited to this. Similarly, the other end portions of the optical fiber group 4 are arranged vertically and horizontally to form the image input surface 3. Note that the arrangement order of the optical fibers 8 is the same between the image output surface 5 and the image input surface 3, but the image input surface 3 is arranged more densely than the image output surface 5 (see FIG. 4). .

  The image input surface 3 is disposed so as to face substantially parallel to the projection surface of the image projector (projector, liquid crystal display, CRT, etc.) 2, and an image (hereinafter referred to as light emitted from the image projector 2). , Referred to as an image S), the light incident on the other end of each optical fiber 8 is guided to one end of the image display unit 7, and the image output surface 5 irradiates the image input surface 3. The same image as the displayed image S is displayed. However, on the image output surface 5, since the optical fibers 8 that are the video display unit 7 are arranged more coarsely than the image input surface 3, the image S is enlarged and displayed.

  In order to form the image output surface 5, one end of the optical fiber 8 is inserted into a through hole 9 (see FIG. 3) provided in the screen substrate 6 and fixed and held. The screen substrate 6 is made of, for example, an acrylic plate. When the image output surface 5 is large, the screen substrate 6 is constituted by connecting a plurality of block bodies 6a (see FIG. 4).

  In the video apparatus using the optical fiber 8, the arrangement of the optical fibers 8 on the image output surface 5 is made at a larger interval than that of the image input surface 3. The input image can be enlarged and displayed. Since such a video apparatus is often installed and used in a facility where people gather, a park, or the like, a screen sheet 30 having a light diffusion sheet 10 (see FIGS. 2 and 3) on the surface of the screen substrate 6. (See FIGS. 2 and 3) to widen the viewing angle of the image. As a result, on the image output surface 5, the viewing angle is widened and the pixel arrangement is coarse (the pixel interval is larger than the optical fiber 8 interval on the image input surface 3). By diffusing, the enlarged image can be displayed on the image output surface 5 without unevenness. 2 and 3, the screen sheet 30 includes a light diffusion sheet 10 and a frame body 31 that fixes the peripheral edge of the light diffusion sheet 10. As will be described later, the light diffusing sheet 10 is made of a woven fabric in which warp yarns and weft yarns are woven into a sheet, and the peripheral portion of the light diffusing sheet 10 is fixed by a frame 31. The weft yarn and the warp yarn are held in tension and the planar state of the light diffusion sheet 10 is held. As a result, it is possible to obtain a clear image in which the weft is not bent and moire is not generated.

  Here, it should be noted that the light diffusing sheet 10 used in the present embodiment is composed of a woven fabric instead of an optical film structure. Specifically, as shown in FIG. 1, a first fiber having a light-transmitting circular or pseudo-circular cross-sectional shape is used as the weft thread 11, the second fiber is used as the warp thread 12, and the weft threads 11 are mutually connected. It is made into a sheet by weaving in parallel and at a predetermined density in an almost intimate arrangement.

  By using the first fiber having a light-transmitting circle or pseudo-circular cross section as the weft thread 11 as described above, it is possible to form a sheet as a densely arranged woven fabric without bending. . As a result, when such a light diffusion sheet is used in a video apparatus, a clear image without moire can be obtained. This point has been proved by experiments of the present inventors described later.

Moreover, the light diffusing sheet 10 according to the present invention composed of a woven fabric has the following effects as compared with a light diffusing sheet composed of an optical film structure. That is, in the case of a light diffusion sheet configured with an optical film structure, even if it has a sufficient light diffusion effect, the light transmittance is not sufficient, so the luminance level in an oblique direction with a slight angle from the front surface, The brightness level is lower than the luminance level at which a clear image can be recognized. Therefore, it is unsuitable for a large screen or the like that requires a wide viewing angle.
On the other hand, in the case of the light diffusing sheet 10 composed of the woven fabric according to the present invention, the light diffusing sheet has almost the same light diffusing effect as the light diffusing sheet composed of the optical film structure, and the light transmittance is the optical film. It is extremely higher than the light diffusion sheet constituted by the structure. Therefore, the luminance level in the oblique direction with a considerably large angular position from the front is higher than the luminance level at which a clear image can be recognized. Therefore, the light diffusion sheet 10 has very good viewing angle characteristics. Moreover, since it has a large light diffusion effect that is almost the same as that of a light diffusion sheet having an optical film structure, the luminance from the oblique direction decreases with a gentle inclination. As a result, since the change in luminance is small both when viewed from the front and when viewed from an oblique direction, it is possible to view the image clearly without any discomfort from any angle position. This point is clearly shown in the examination of experimental results described later (FIG. 10).

  Here, specific examples of the highly light transmissive strand used for the weft 11 include polymethyl methacrylate optical fiber, polyethyl acrylate optical fiber, nylon monofilament, and polyethylene terephthalate monofilament. Of course, the fiber having high light transmittance is not limited to these.

  In order to increase the light diffusion effect, the weft yarns 11 are preferably arranged without gaps as much as possible. When expressed in terms of the weft density, it is preferably [1 (cm) / weft diameter (cm)] × 0.5 (lines / cm) or more. Here, the weft density means the number of wefts present per 1 cm of the fabric. For example, when the weft yarn diameter is 0.2 cm, the weft yarn density is 1 / 0.2 = 5 (lines / cm) as shown in FIG. In the actual fabric, as shown in FIG. 6 (2), since the warp yarn 12 is interposed between the weft yarn 11 and the weft yarn 11, the weft yarn cannot be arranged completely without a gap. Has occurred. This gap is preferably as small as possible. Therefore, the coefficient indicating the reduction rate of the weft density by the warp yarn 12 is set to 0.5 or more. That is, the weft density was set to [1 (cm) / weft diameter (cm)] × 0.5 (lines / cm) or more. The reason why the coefficient indicating the reduction rate is regulated to 0.5 or more is that if the value is less than 0.5, the interval between the wefts becomes too large, and it is not suitable as a light diffusing sheet due to a decrease in image quality. .

  Moreover, it is preferable that the material of the fiber of the warp yarn 12 is composed of a synthetic fiber that is soft and has high light transmittance. This is because if the light transmittance is high, the light transmittance can be maintained high. Specific examples include polyamide fibers and polyester fibers. Of course, the fibers used for the warp yarn 12 are not limited to these. For example, a polymethyl methacrylate optical fiber or a polyethyl acrylate optical fiber may be used.

  Further, in the case of the light diffusion sheet 10 for an optical fiber imaging device according to the present embodiment, it is preferable that the thickness of the fiber used for the warp yarn 12 is smaller than that of the light-transmitting strand used for the weft yarn 11. This is because if the warp yarn is thicker than the weft yarn, the weft yarn bends, resulting in moiré in the projected image. The diameter ratio between the warp yarn 12 and the weft yarn 11 is preferably set to (warp yarn diameter / weft yarn diameter) ≦ 0.2.

  Further, the density of the warp yarn 12 is the minimum number necessary for constituting a woven fabric in order to achieve high light transmittance. Specifically, the warp yarn 12 has an area occupied by the warp yarn 12 on the fabric surface of 30% or less. This is because if the density of the warp yarns 12 is large, the light-shielded area increases and the light diffusion effect is reduced.

Moreover, it is preferable that the diameter of the weft 11 is equal to or smaller than the image display unit 7 of the image apparatus. The reason for this restriction is as follows. In the case of a large screen, as described above, the screen substrate 6 is formed by joining a plurality of block bodies 6a. Since it is difficult to perform the joining of the block bodies 6a with high accuracy, the video display units 7 are not all equal in pitch P. Further, since the light diffusion sheet 10 side also has a woven structure, it cannot be woven at regular intervals. Therefore, the light diffusing sheet 10 installed on the screen substrate 6 and the image display unit 7 cannot be aligned with high accuracy in actuality, and thus a deviation may occur. Due to this, there is a possibility that a state in which no single weft 11 passes through the image display unit 7 may occur. However, if such a state occurs, there is a single image display 7 in which light is not diffused, resulting in display unevenness. However, by setting the diameter of the weft thread 11 to be equal to or smaller than that of the image display unit 7, at least one weft thread passes through the image display unit 7, and a light diffusion effect can be obtained in each image display unit 7. As a whole, display without display unevenness is possible.
From the viewpoint of obtaining a clear image with a wider viewing angle, it is preferable to select a weft thread diameter so that at least about 2 to 3 weft threads 11 pass through all the video display units 7.

  Specific examples of the weave structure constituting the light diffusion sheet 10 include plain weave, twill weave, satin weave, and the like. The weft yarns of FIG. 1 are not limited to this as long as they can form a woven structure in which the weft yarns are not bent and can be arranged in parallel and in close proximity to each other.

  Next, an aspect of installation of the screen sheet 30 including the light diffusion sheet 10 on the screen substrate 6 will be described. When installing the screen sheet 30, the light diffusion sheet 10 is installed so that the fiber axis of the plastic optical fiber (the fiber axis of the weft thread) is along the Y direction of the screen substrate 6 as shown in FIG. Alternatively, as shown in FIG. 7 (2), the plastic optical fiber fiber axis (weft fiber fiber axis) is installed along the X direction of the screen substrate 6. In the former case, the viewing angle in the horizontal direction (X direction) of the video display surface is increased. In the latter case, the viewing angle in the vertical direction (Y direction) of the video display surface is increased.

  Also, as shown in FIGS. 7 (3) and (4), two woven fabrics are laminated, and the fiber axis of the plastic optical fiber (fiber axis of the weft) is the one in the Y direction and the one in the X direction. A light diffusion sheet having a laminated structure may be used. By installing the screen sheet including the light diffusion sheet having such a laminated structure on the screen substrate 6, the viewing angle in the X direction and the Y direction can be expanded. Each piece of fabric has the same configuration as the light diffusion sheet in the first embodiment.

(Embodiment 2)
FIG. 8 is a perspective view of a light diffusion sheet 10A according to the second embodiment.
The light diffusing sheet 10A according to the second embodiment is used as a light diffusing sheet for an LED video device in which the pitch of the video display unit 7 is coarser than that of an optical fiber video device. The light diffusion sheet 10 </ b> A has a woven structure in which warp yarns 12 and weft yarns 11 are woven in a mesh shape. As a material of the warp yarn 12 and the weft yarn 11, a plastic optical fiber is used for one or both. Further, even if the diameters of the warp yarn 12 and the weft yarn 11 are approximately the same or the warp yarn 12 is large, it is possible to obtain a clear image without moire. This is because even if the warp yarn 12 is thicker than the weft yarn 11, the crossing portion 20 hardly bends. Therefore, if the intersecting portion 20 is configured to completely cover the image display unit (corresponding to one LED) 7 of the LED image device, a clear image without moire can be obtained. Note that the present invention can be widely applied not only to the LED video device but also to other video devices having a low density. Further, the light diffusing sheet 10A according to the present embodiment is also fixed to the peripheral portion of the light diffusing sheet 10A by the frame body 31 in order to maintain a planar state similarly to the light diffusing sheet 10 according to the first embodiment. It is installed in the LED video device as a screen sheet.

(Other matters)
(1) In the above embodiment, the light diffusing sheet for a video device has been described. However, the present invention is not limited to this, and can be applied to a light diffusing sheet for a lighting device.

(2) In the above embodiment, the frame 31 that fixes the peripheral edge of the light diffusing sheet is exemplified as the holding means that holds the state where tension is applied to the warp and weft of the light diffusing sheet. Is not limited to this, and the following holding means can also be used.
Sandwich with film while applying tension to warp and weft. If only the light diffusing sheet is used, the surface is uneven so that dust is likely to be clogged. However, if such a structure is sandwiched with such a film, the clogging of dust can be eliminated because the film surface is a flat surface having no unevenness.
Further, an acrylic plate may be used in place of the film.
Further, the sandwiched sheet may be attached in a tile shape for each block.

  The light diffusion sheet according to the first embodiment, which is a light diffusion sheet (hereinafter referred to as the present invention X1) in which warp yarns and weft yarns of the following conditions are woven in plain weave, and the laminated structure according to the first embodiment. The viewing angle characteristics of the light diffusion sheet (hereinafter referred to as the present invention X2) and the commercially available light diffusion sheet (hereinafter referred to as Comparative Example Y) were evaluated.

(1) Conditions of Invention X1 of the Present Invention / Weft Conditions Weft Material: Plastic optical fiber mainly composed of polymethyl methacrylate (PMMA) (hereinafter referred to as POF)
Weft diameter: 0.25 mm (Note that the diameter of the image display unit 7 is smaller than 0.75 mm)
-Warp conditions Warp material: Polyester bright monofilament Warp diameter: 22 dtex (diameter 40 μm)
Warp yarn density: 45 / cm

(2) Conditions of Invention X2 This invention uses a light diffusion sheet having a laminated structure in which two woven fabric light diffusion sheets manufactured under the same conditions as in Invention X1 are laminated so that the POF fiber axes are orthogonal to each other. .

(3) Conditions for Comparative Example Y The light diffusing sheet having the optical film structure was designated as Comparative Example Y.

(4) Measurement conditions and measurement method Light source: 150 W halogen lamp Measurement method: A light diffusion sheet is installed on the front surface of the screen substrate of the optical fiber imaging apparatus according to the first embodiment, and the brightness at a distance of 1 m therefrom is obtained. Measured with a luminance meter. Also, the luminance was measured in the same manner when no light diffusion sheet was installed.
In addition, this invention X1 was installed in the state of FIG. 7 (1) of a screen board | substrate, and this invention X2 was installed so that the fiber axis of one POF might become the X direction of a screen like FIG. 7 (3).

(Experimental result)
The viewing angle characteristics are shown in FIGS. FIG. 9 is a graph showing the luminance attenuation rate with respect to the viewing angle, and FIG. 10 is a graph showing the luminance rate with respect to the viewing angle. In FIG. 9, the luminance attenuation rate when the light diffusion sheet is not installed is also plotted.
In addition, “luminance ratio” in FIG. 10 indicates a ratio (in% display) of the luminance with the light diffusion sheet to the luminance without the light diffusion sheet. Therefore, the luminance is equal to that without the light diffusion sheet at a luminance rate of 100%.

(Examination of experimental results)
As is clear from the results of FIG. 9, when the POF fabric developed this time is installed in the video apparatus (in the case of the present invention X1 and X2), when the viewing angle is about 0 to 12 degrees, there is no light diffusion sheet The brightness is attenuated in substantially the same way. However, in the case of the inventions X1 and X2, it is recognized that when the viewing angle is about 12 degrees or more, the luminance attenuation is greatly suppressed as compared with the case without the light diffusion sheet. That is, even when the angle is gradually increased from the front of the image, it is recognized that the rate of luminance attenuation changes gently. This means that even if an image is viewed at a wide range of angular positions, it can be recognized as a clear image. That is, it is understood that when the inventions X1 and X2 of the present application are installed in a video apparatus, an excellent effect is obtained that a wide viewing angle characteristic can be obtained. In particular, when POF is laminated with two layers of POF fabric in the vertical direction of XY, it is almost the same as FIG. 9 showing the characteristics in the X direction (horizontal direction in the video apparatus) in the Y direction (vertical direction in the video apparatus). Similar characteristics have been confirmed. As a result, an effect of widening the viewing angle in all directions can be obtained, and it has been found that this is suitable as a light diffusion sheet.
Moreover, in FIG. 10, it compared with the commercially available light-diffusion sheet. In the numerical value compared with the luminance of the video device alone, it can be seen that the POF fabric (the present invention X1, X2) shows a higher numerical value than the commercially available light diffusion sheet (Comparative Example Y), and the decrease in luminance is small. In addition, since the graph shapes of the inventions X1 and X2 and the comparative example Y are substantially the same, it can be determined that the light diffusion effect of the inventions X1 and X2 is substantially the same as the light diffusion effect of the comparative example Y. Therefore, the inventions X1 and X2 of this application are considered to have a light diffusion effect comparable to that of Comparative Example Y while maintaining a high light transmittance. This is presumed to be due to the fact that POF has a higher light transmittance than the optical film structure, and when actually installed in a video apparatus, the POF fabric (present inventions X1 and X2) is bright with a wide viewing angle. It means that a clear image can be realized. That is, it means that the POF woven fabric (the inventions X1 and X2 of the present invention) has an extremely good viewing angle characteristic compared to a commercially available light diffusion sheet (Comparative Example Y).
In addition, when it is necessary to increase the viewing angle in only one of the X direction (left and right direction of the video device) or the Y direction (vertical direction of the video device), it is more commercially available to install one POF fabric. A bright image more than doubled is obtained (FIG. 10), which is effective.

  The light diffusion sheet according to the present invention is suitably applied to a light diffusion sheet of a large-sized image device such as an optical fiber image device.

FIG. 3 is a perspective view of a light diffusion sheet according to Embodiment 1. 1 is an overall configuration diagram of a video device using a light diffusion sheet according to Embodiment 1. FIG. Sectional drawing of the screen in an imaging device. The front view of the screen in an imaging device. FIG. 5 is a partially enlarged view of FIG. 4. The figure for demonstrating the weft density. The figure which shows the installation state of a light-diffusion sheet. FIG. 9 is a perspective view of a light diffusion sheet 10A according to Embodiment 2. The graph which shows the luminance decay rate with respect to a viewing angle. The graph which shows the luminance rate with respect to a viewing angle.

Explanation of symbols

1: Optical fiber image device 2: Image projector 3: Image input surface 4: Optical fiber group 5: Image output surface 6: Screen substrate 7: Single image display 8: Optical fiber 10, 10A: Light diffusion sheet 11: Weft 12 : Warp yarn 20: Intersection 30: Screen sheet 31: Frame

Claims (5)

A light diffusing sheet composed of a first fiber having a light-transmitting circular or pseudo-circular cross-sectional shape and a woven fabric woven using only the second fiber ,
The second fiber is thinner than the first fiber,
Wherein the first fiber is used as a weft, said second fibers used as warp, the weft is parallel to each other, characterized in that it comprises a bend without having approximately closely arrayed weave structure A light diffusion sheet. The light diffusion sheet according to claim 1, wherein the second fiber has a diameter ratio of 0.2 or less than that of the first fiber . The light diffusing sheet according to claim 1 or 2 is sandwiched by a film or an acrylic plate in a state where tension is applied to the warp yarn and the weft yarn, and the light diffusing sheet having flatness is adhered to the screen substrate. A screen sheet characterized by that. 4. The screen substrate is constituted by connecting a plurality of block bodies, and the light diffusion sheet having the planarity is affixed to the screen substrate for each block body. The screen sheet described. A video system comprising a video display source configured by arranging a large number of video display units at a predetermined pitch, and a screen sheet provided on the front side of the video display source,
The screen sheet is
A first fiber of two kinds of fibers, a first fiber having a light-transmitting circle or pseudo-circular cross-sectional shape and a second fiber thinner than the first fiber, is used as a weft. A light diffusion sheet composed of a woven fabric woven in a mesh shape with a predetermined number of warp yarns and weft yarns,
A frame for fixing the peripheral edge of the light diffusion sheet;
With
In the light diffusion sheet, at the intersection where the warp and weft intersect, the weft is parallel to each other, not bent, and arranged substantially closely, and the interval between the intersections is substantially equal to the predetermined pitch of the image display unit. It has a woven structure that is knitted to be equal,
The video system, wherein the light diffusing sheet is arranged so that an intersection portion covers a single video display.