JPH07318708A - Light transmission type light diffusion sheet, image display device and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] An image display that has a wide viewing angle for an optical image on the image display surface and that provides a bright and clear image without causing difficulty in recognizing image information due to reflection of ambient light. An apparatus and a manufacturing method thereof are provided. [Structure] After arranging one end surface of a large number of optical fibers 8 on the image display surface 3 in a plane, a photosensitive transparent resin sheet 11 containing a light diffusing agent is attached, and light is applied to the other end surface of the optical fibers 8. After the light is projected to cure the photosensitive transparent resin around the end face of each optical fiber 8, the uncured portion is dissolved and removed to form a large number of microlens-shaped light diffusion layers 4, thereby displaying an image of an optical image. An image display device having surface 3 formed, a method for manufacturing the same, and a light transmission type light diffusion sheet used therefor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light transmitting type light diffusing sheet, an apparatus for transmitting and displaying an image using an optical fiber, and a method for manufacturing the same. More specifically, it relates to a light-transmitting type light diffusing sheet for projecting and transmitting light from the back surface of the sheet to suitably display an image on the sheet surface, or for obtaining a uniform surface light source, and to increase the size. The present invention relates to an image display device having a wide viewing angle, less susceptible to ambient light, and capable of displaying a clear image with high resolution, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, large screens have come to be used for displaying information and guidance at stations and airports, or as screens for explaining various shows and exhibitions.
In these large screens, the image on the light source side must be enlarged and projected on the screen display surface. At this time, whether the image projection system is a rear projection system or an image display system using an optical fiber, a lenticular lens or a light diffusion plate is used on the screen display surface to widen the viewing angle. .

In particular, the light diffusing plate and sheet are used for illumination, signboards and various light sources to ensure uniform brightness in addition to the above-mentioned ones. Recently, word processors and O
It has been used as a diffusing material for a backlight light source of a liquid crystal display and a liquid crystal color television used in the A-equipment, and has also been used as a diffusing plate for widening the viewing angle of a liquid crystal display.

In any of these applications, they play a role of compensating for the phenomenon that the characteristic that light travels straight ahead is an obstacle. That is, since the light has directivity, the light from the back of the display surface can be seen well from the front, but becomes hard to see when the angle formed with the vertical of the display surface becomes large. It has the drawback that the so-called viewing angle is narrow and the viewing angle is small.

In particular, in the case of a large screen which is premised on being viewed by a large number of people at once, a lenticular lens or a light diffusing plate is required as the above-mentioned means for diffusing emitted light over a wide angle.

However, although these means can certainly improve the viewing angle to some extent, conversely, the entire brightness is lost or reflected light of environmental disturbance is mixed with the image information to be originally displayed. Then, there is a problem that the image becomes unclear, specifically, the resolution and the contrast of the image decrease.

Therefore, the prior art has not sufficiently satisfied both the characteristics of high light transmissivity capable of maintaining the brightness when viewed from the front and high light diffusivity capable of increasing the viewing angle.

As an apparatus for transmitting and displaying an image using an optical fiber, there is an apparatus called an image guide or an image scope for displaying a full-size image. As an image display device having a magnifying function, there is also known an image display device in which an interval between optical fibers on an image display surface is made larger than that on an incident surface to form a large screen having a screen size of several meters.

In any case, the image display surface (screen surface) is formed by the cut end surface of the optical fiber (optical fiber). The light emitted from the end surface of the optical fiber has a strong directivity, and an angle within a certain range with respect to the image display surface,
That is, although it can be seen well from a direction close to vertical, it becomes very difficult to see as the angle formed by the direction perpendicular to the image display surface increases. The reason for this is that the exit angle of light is limited by the numerical aperture of the optical fiber, and such a conventional device has a drawback that the viewing angle is narrow. Therefore, in the case of a large screen which is supposed to be viewed by a large number of people at once, some means for diffusing the emitted light in a wide angle is required.

The conventional techniques for this problem are roughly classified into a light-scattering plate, a light-scattering film, and the like on the image display surface (hereinafter sometimes referred to as the screen surface when mainly targeting a large screen). It can be classified into two methods, that is, a method of attaching and scattering the light emitted from the optical fiber, and a method of providing a light scattering structure on the end face of each optical fiber from which light is emitted.

In the former method, since both the light scattering plate and the light scattering film have the property of reflecting ambient light, the reflected light mixes with the image information to be originally displayed, resulting in an unclear image. However, there is a problem that the resolution and contrast of the image are lowered.

Regarding the latter method of providing a light scattering structure only in the light emitting portion, it is necessary to process each end face of a large number of optical fibers into a shape in which light is easily scattered, especially on a screen surface of hundreds of thousands. It was practically impossible for a large screen with the optical fibers.

On the other hand, a method of laminating optical fiber bundles in parallel with each other with a predetermined angle inclined with respect to the screen surface, that is, cutting the optical fibers at an angle shallower than perpendicular to the axis,
A method of forming a screen surface with the cut end surface has been proposed (for example, Japanese Patent Laid-Open No. 61-11782).

However, in this method, the magnification ratio with respect to the incident surface and the degree of scattering of the screen surface, that is, the viewing angle are determined at the same time depending on how much the axial direction of the optical fiber bundle is inclined with respect to the screen surface. , There was a problem that they could not be adjusted independently.

[0015]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to have a high light transmittance, a wide viewing angle, and it becomes difficult to recognize image information due to reflection of ambient light. The present invention provides an image display device capable of obtaining a clear image with high resolution and high resolution, and a method capable of efficiently and easily manufacturing the device, and also capable of being used for the image display device and having uniform brightness. An object of the present invention is to provide a light transmission type light diffusion sheet that can be used as a surface light source.

[0016]

In order to achieve the above object, a light transmission type light diffusion sheet according to the present invention is a light transmission type containing a light diffusion agent which is fine particles of a transparent or semitransparent organic resin. In the light diffusing sheet, (a) the resin forming the light diffusing sheet is made of a transparent or semitransparent organic resin, the refractive index of which is X, and the resin of the organic resin forming the light diffusing agent fine particles is When the refractive index is Y, X <Y, and (b) the concentration of the light diffusing agent particles added to the resin forming the light diffusing sheet is 1% by weight or more and 15% by weight or less. It consists of

Further, the light diffusing sheet is formed of a photosensitive resin, and is configured as a light transmitting type light diffusing sheet which is water-soluble or alcohol-soluble in the uncured state.

When the thickness of the light diffusion sheet is T (μm) and the concentration of the fine particles of the light diffusion agent added to the resin forming the light diffusion sheet is C (% by weight), 500 ≦ T × C
It is preferable to satisfy ≦ 5000.

The image display device according to the present invention is an image display device in which one end surface and the other end surface of a large number of optical fibers are arranged on an image display surface and an image incident surface, respectively. Is a light-transmitting light diffusing sheet containing a light diffusing agent which is fine particles of a transparent or semi-transparent organic resin, and (a) the resin forming the light diffusing sheet is a transparent or semi-transparent organic resin. When the refractive index of the resin is X and the refractive index of the organic resin forming the light diffusing agent fine particles is Y, X <Y and (b)
The light diffusion layer is formed of a light transmission type light diffusion sheet in which the concentration of the fine particles of the light diffusion agent added to the resin forming the light diffusion sheet is 1% by weight or more and 15% by weight or less. Become.

Further, the image display device according to the present invention is an image display device in which one end surface and the other end surface of a large number of optical fibers are arranged on an image display surface and an image incident surface, respectively. Is a large number of light diffusion layers made of a photo-curable photosensitive resin formed at the end of each optical fiber are distributed as button-shaped islands, and the button-shaped islands are
It is characterized in that it is formed as a microlens having a large number of particulate light diffusing agents added therein. Here, it is preferable that a large number are distributed as convex lens-shaped islands in which the light diffusion layers are connected to each other, that is, as convex lens-shaped islands in which the skirts are connected to each other.

Further, in each of the above image display devices, it is preferable that the surface of the light diffusion layer is protectively coated with a waterproof resin in order to have practicality.

The water resistant resin is preferably an acrylic polymer lacquer or an acrylic photocurable resin, and the photosensitive resin is preferably water-soluble or alcohol-soluble in the uncured state. Such a water-soluble or alcohol-soluble photosensitive resin comprises, for example, a resin composition containing polyvinyl alcohol or polyamide as a main component.

Further, in the image display device according to the present invention, one end surface and the other end surface of the optical fiber bundle in which a large number of optical fibers are bundled are arranged on the image display surface and the image incident surface of the optical image, respectively. In the image display device, (a) a light-diffusing layer made of a transparent or semitransparent photocurable photosensitive resin formed on an end portion of each optical fiber is formed on the image display surface in the form of a convex lens. As the light-diffusing agent, which is a fine particle of a transparent or semi-transparent organic resin, and the refractive index of the photosensitive resin is X, which is the light-diffusing agent. When the refractive index of the organic resin is Y, X <
Y, and (b) the concentration of the light diffusing agent added to the photosensitive resin is 1% by weight or more and 15% by weight or less.

When the height of the convex lens is H (μm) and the diameter of the optical fiber is d (μm), 1/4 ≦ H / d
Satisfies ≦ 2, and the diameter of the skirt of the convex lens is D
(Μm), where the pitch of the array of optical fibers on the image display surface is L (mm), 1.1 ≦ D / d, D / L
It is preferable to satisfy ≦ 750.

The image display device as described above is manufactured by the following method. That is, the manufacturing method of the image display device according to the present invention, a large number of optical fibers, after arranging and aligning one end surface of the optical fibers so as to be flat on the image display surface, transparent to the image display surface. Alternatively, a light transmissive light diffusing sheet containing a light diffusing agent that is fine particles of a semitransparent organic resin, wherein (a) the resin forming the light diffusing sheet is made of a transparent or semitransparent organic resin. When the refractive index is X and the refractive index of the organic resin forming the light diffusing agent fine particles is Y, X <Y, and
(B) The method is characterized in that the addition concentration of the light diffusing agent fine particles to the resin forming the light diffusing sheet is 1% by weight or more and 15% by weight or less and a light transmitting type light diffusing sheet is attached.

Further, in the method for manufacturing an image display device according to the present invention, a large number of optical fibers are arranged in such a manner that one end surfaces of the optical fibers are flat on the image display surface, and then the image display surface is formed. , A light-transmissive light diffusion sheet made of a water-soluble or alcohol-soluble photosensitive resin is attached, and then the other end surface of the optical fiber is irradiated with light, and the irradiated light is emitted from the one end surface to obtain an image. The method is characterized by reacting and curing a photosensitive resin located around the one end surface of the optical fiber on the display surface.

Here, before the light diffusing sheet is attached to the image display surface, a uniform adjustment is made in advance so that a part of the bottom surface or all layers of the sheet layer are exposed from the side to be the attachment surface of the light diffusing sheet. It is preferable that the light irradiation is performed.

In the above method, after the photosensitive resin around the one end face of the optical fiber is reactively cured, the uncured portion is dissolved and removed with water or warm water to remove each optical component on the image display surface. A light scattering portion is formed on the fiber end surface portion.

Further, a part or the front part of the uncured portion of the above-mentioned photosensitive resin is dissolved and removed with water or warm water, and after drying, the entire image display surface is irradiated with light to completely cure the photosensitive resin. Preferably.

Further, it is preferable that the light transmission type light diffusing sheet made of the above-mentioned photosensitive resin contains a particulate light diffusing agent. This light diffusing agent is made of, for example, an organic resin. The refractive index of the light diffusing agent is preferably higher than that of the photosensitive resin.

In the above method, it is preferable to use a substantially transparent photosensitive resin as an adhesive when the light transmission type light diffusing sheet made of the photosensitive resin is attached to the image display surface. Here, "substantially transparent" means transparent or translucent. Then, as the adhesive, for example, a substantially transparent epoxy resin is used, and the film is exposed to light in a semi-cured state of the epoxy resin,
After the epoxy resin is completely cured, a method of washing and removing the uncured portion of the film can be used.

Further, in the above method, after the uncured portion is dissolved and removed, many cured photosensitive resins remain on the image display surface. Each of the remaining photosensitive resin portions is formed in a convex lens shape.

In the above method, the thickness of the light transmission type light diffusion sheet made of the photosensitive resin is T (μm),
When the target height of the convex lens is H (μm), it is preferable that T≈1.1H.

After the uncured portion was dissolved and removed with water or warm water to remove the convex lens-shaped light diffusion layer, the entire display surface including the lens was coated with a transparent waterproof resin. It is preferable to protect the convex lens that is the light diffusion layer.

The image display device according to one embodiment of the present invention will be described below by taking a case of forming a large screen as an example. FIG. 1 is a schematic view of an embodiment of an image display device according to the present invention. In FIG. 1, reference numeral 1 denotes a bundle of optical fibers for transmitting image information such as an optical image. 2 is an image incident surface in which the end faces of the individual optical fibers 8 are closely arranged in a plane, and 3 is an array in which the optical fibers 8 are similar to the incident surface 2 and has a lower density than the incident surface 2. The image display surface arranged, that is, the screen surface. Also,
Reference numeral 4 on the display surface 3 is a cured region of a transparent resin formed on the emission end face 7 of each optical fiber 8 by a method described later, that is, a microlens formed in a convex lens shape (hereinafter referred to as a microlens). .), Which is a light diffusion layer. As a method of making an image incident on the image incident surface 2, for example, a transmissive liquid crystal screen is brought into close contact with the image incident surface and light is applied from the back surface, or an image is directly projected on the incident surface by a projector or a video projector.

FIG. 2 is an enlarged plan view of the microlens 4 portion of FIG. 1, and FIG. 3 is a sectional view of the microlens 4 portion of FIG. Each optical fiber 8 is sharply cut with its end face aligned with the surface of the support plate 3a forming the screen face 3 (image display face), and the microlens 4 is formed on the end face 7. Reference numeral 5 is a photosensitive resin that constitutes the microlens 4, and 6 is a light diffusing agent added to the photosensitive resin.

FIG. 4 is a view showing a specific method for forming the light diffusing microlens 4 in the present invention, and an example of the manufacturing method according to the present invention will be described based on this drawing. First, the light transmission type light diffusion sheet 11 made of a water-soluble photosensitive resin having a thickness of several tens of μm to several thousands of μm, to which the light diffusing agent 6 is added, on the support plate 3a is attached to another photosensitive transparent resin or transparent Attach using epoxy resin as an adhesive. Then, light having a wavelength suitable for curing the photosensitive resin is irradiated from the image incident surface 2 by the light source 9 so that the light is emitted from the individual optical fibers 8.
The light is transmitted to the image display surface by itself, scattered by the light diffusing agent 6, and the microlens 4 which is a cured region of the resin corresponding to the intensity of light in each direction is formed in the peripheral portion of the end surface of the optical fiber. After irradiation for a certain period of time (details will be described later), the uncured resin is dissolved and removed with water or warm water, so that only the cured resin remains on the screen surface 3 and microlenses 4 are formed at each end of each optical fiber. To be done.

The water-soluble photosensitive resin used herein is preferably a semitransparent one that does not interfere with the transmission of visible light, or preferably a transparent one. A polymer compound having a group capable of undergoing a crosslinking reaction by light, a photocrosslinking agent. It is possible to use a polymer compound which becomes a photosensitive material by mixing the above, or a resin such as a monomer which is polymerized by light. Alcohol-soluble resin may be used, but water-soluble resin is more preferable because of ease of processing and economy. Of these, water-soluble photosensitive resins such as polyamide and polyvinyl alcohol are particularly preferable from the viewpoint of curing stability and adhesiveness to optical fibers. However, when the lens is not formed, that is, when the light diffusion sheet 11 is simply attached, an alcohol-soluble resin is preferably used from the viewpoint of water resistance. Further, in the present invention, the definition of photosensitivity broadly includes a resin curable by light such as visible light, electron beam and X-ray, but an ultraviolet curable resin is preferable from the viewpoint of easy availability and easy handling. The photosensitive resin is used to form a film-like sheet to which a diffusing agent is added by utilizing the change in viscosity due to temperature, solvent and the like.

The irradiation light source 9 is selected according to the characteristics of the resin used. For example, in the case of a general ultraviolet curable resin, it is preferable to generate ultraviolet rays having a wavelength of 300 to 400 nm, and a metal halide lamp, a high pressure mercury lamp, a mercury xenon lamp, etc. are suitable.

The light transmission type light diffusing sheet 11 made of a photosensitive resin may be made of only a photosensitive resin, but preferably contains the following light diffusing agent. The light diffusing agent to be added is preferably a transparent granular material having a particle diameter larger than a visible light wavelength of 800 nm, and a known inorganic material granular material or a shell composed of an organic material is found in the conventional proposals. Certainly, the fine particles of alumina, which is an inorganic material, also exert a sufficient effect in terms of diffusion. However, since alumina, which is a diffusing material, reflects and scatters light, but does not transmit it,
It causes a decrease in brightness. So, as a result of diligent examination,
It has been found that a shell body which is a transparent or semi-transparent organic resin composition and has a higher refractive index than a photosensitive resin is more preferable.

As the resin which is convenient for transmitting and scattering light, specifically, urea resin, polycarbonate, polyester resin, styrene resin, carboxylic acid-formalin resin, vinylidene chloride resin, acrylonitrile-styrene copolymer, etc. A shell made of

Here, it is preferable that the refractive index of the resin composition used as the light diffusing agent is higher than the refractive index of the photosensitive resin. That is, the light projected from the incident surface and transmitted through the optical fiber is transmitted to the light diffusion layer on the end surface of the optical fiber. This light must be diffused by the light diffusing agent in the light diffusing layer, and has a wide viewing angle and high visibility when emitted from the light diffusing layer.

When the refractive index of the added light diffusing agent is lower than that of the photosensitive resin forming the light diffusing layer,
Since the proportion of the light totally reflected at the interface with the diffusing agent becomes extremely high, the light emitted from the light diffusing layer becomes weak.
That is, not only the image becomes dark, but also the spread of light cannot be expected, so when the viewing angle is widened, the brightness may be low and the image may not be seen at all.

Therefore, in order to transmit and scatter light in a desired state, it is preferable that the refractive index of the light diffusing agent is higher than that of the photosensitive resin, and the organic resin composition as described above is effective. is there.

Further, as a specific method when such a light diffusing agent is used, a granular body of several μm to several tens of μm
It is effective to add 20% by weight, preferably 1 to 15% by weight. If the addition amount of the light diffusing agent is larger than this, the light transmission will be hindered, and the brightness for visually recognizing information,
That is, the brightness is insufficient. On the other hand, if the addition amount is less than the above range, the light diffusion is small, the effect of improving the brightness at the viewing angle cannot be obtained, and the brightness retention rate with respect to the front brightness is reduced. Hard to get.

In the light diffusing layer using the light transmitting type light diffusing sheet having the above-mentioned structure, it is not always necessary to form the convex lens-shaped microlenses 4. Therefore, the resin forming the light diffusion sheet does not have to be a photosensitive resin, but is a transparent or semitransparent organic resin composition, and the diffusion effect can be exhibited by satisfying the above conditions.

This means that a light diffusing agent satisfying the above conditions is compounded with an ordinary resin such as polyamide polymer, polyvinyl chloride, polyethylene, polyester, polymethylmethacrylate etc. to form a film-like sheet. This means that it is possible to form a diffusion layer. However, if it is in such a sheet shape, it will be difficult to visually recognize the image on the screen surface due to reflection of environmental disturbance light, so it is a point to improve the visibility by eliminating or weakening the surface gloss with a matte lacquer etc. is there.

From this point of view, it can be said that it is preferable to form a large number of microlenses whose screen surface is pear-shaped. As a result of earnest studies for practical application of the sheet-shaped light diffusing layer or the microlens 4, as a result of the above-mentioned range of the refractive index of the light diffusing agent and the addition amount, the sheet thickness or the lens height is the viewing angle. It was found to be important for maintaining the brightness.

Since the microlens is formed by the above-mentioned method from the light transmission type light diffusion sheet made of water-soluble photosensitive resin, the height of the lens corresponds to the thickness of the sheet. The thickness of the light transmission type light diffusing sheet is T (μm), and the concentration of the light diffusing agent particles added to the resin composition of the light diffusing sheet is C.
When it is (% by weight), it is preferable that 500 ≦ T × C ≦ 5000.

When T × C is less than 500, even if the front luminance is high and bright, the luminance retention rate at the viewing angle is too low, and the visibility is lost. On the other hand, when it exceeds 5,000, not only the sheet thickness is too thick or the concentration of the diffusing agent is too high, but the front brightness is lowered, and more material is consumed than necessary, which is uneconomical and not preferable in practice.

By forming the display surface of the video screen by using the light transmission type light diffusion sheet having the thickness as described above, an image with good visibility can be displayed in a bright and wide viewing angle.

When the light transmission type light diffusing sheet is made of a water-soluble photosensitive resin, a large number of microlenses, which are light diffusing layers serving as islands in the form of convex lenses, should be formed by the method described above. You can

Further, microlenses may be individually formed around the end faces of the optical fibers, but in order to improve the physical adhesion and stability so that the lenses do not fall off due to impact or the like. In addition, it is preferable to form convex lens-shaped islands that are continuous with each other. In order to make a large number of continuous convex lenses, in the process of forming the lens described above, when the uncured resin is dissolved and removed with water or warm water, it is achieved by leaving the uncured resin appropriately without completely removing the resin. it can. By irradiating light again from the display surface side to cure the remaining uncured resin, all the resins can be completely cured.

In this case, before the photosensitive light-transmitting light diffusing sheet is attached to the display surface, light of appropriate energy is exposed from the bottom surface, which is the attachment surface of the sheet, to a part or all of the bottom layer. By doing so, the control of the removal of the uncured resin can be made easier.

In the above-mentioned microlens 4, especially when an inorganic reflection-scattering type diffusing agent is used, the lens height, lens type and the like are important for maintaining the viewing angle luminance and the sharpness of the image.

That is, the lens height H (μm) is displayed by the height from the end face of the optical fiber to the apex of the microlens 4,
When the diameter of the optical fiber used is d (μm),
A preferable lens height H is H / d in the range of 1/4 or more and 2 or less. When H / d is less than 1/4, the brightness retention rate at the viewing angle is too low even if the front brightness is high,
When it exceeds 2, the height of the lens is too high and the front luminance is lowered, and the lens is easily damaged by impact or the like, which is not preferable in practical use.

Further, the diameter D (μ
m) is D / when the diameter of the optical fiber is d (μm) and the pitch of the array of each optical fiber on the display surface is L (mm).
It is preferable that d satisfies 1.1 or more and D / L 750 or less. If the D / d is less than 1.1, it becomes difficult to sufficiently cover the end face of the optical fiber with the button-shaped microlens, the brightness at the viewing angle becomes low, and the emitted light becomes non-uniform, resulting in a poor image quality. There is a risk that the quality of the product will deteriorate significantly. By increasing the lens diameter D by 10% or more of the diameter of the optical fiber, an ideal lens shape having a wide viewing angle is obtained in the balance between the lens height and the lens diameter.

If the D / L exceeds 750, the emitted light will be diffused too much, and the brightness from the front of the screen will be insufficient. In particular, in the case of an inorganic diffusing agent, the sharpness of the image will be sharpened. Can no longer be maintained. That is, the member forming the support plate 3a, which is the ground portion of the screen surface 3, is preferably a dark-colored body, particularly a black-colored body. Materials such as ceramics, metals, and polymers can be used as the support plate 3a, but polymeric materials such as polyester, polyamide, ABS, and vinyl chloride are preferable in terms of workability, adhesiveness, weight, and the like. . The area of this ground portion is preferably 50% or more of the area of the image display surface 3 in order to maintain image contrast, and the above D / L of 750 or less can satisfy this condition.

In order to form the microlens having the diameter D as described above, it is desirable to add the light diffusing agent as described above. If the light diffusing agent is not present in an appropriate amount, the light travels straight and cannot form a microlens having a target diameter because there is no spread due to scattering.

Here, the button-shaped microlens 4 of the present invention
There is a great advantage in using the light transmission type light diffusion sheet 11 made of a photosensitive resin having water solubility as shown in FIG. The advantage of forming a microlens using the light transmissive light diffusing sheet 11 made of the photosensitive resin does not depend on the plane accuracy of the screen display surface as when forming a microlens by applying a liquid resin. There is a good thing. That is, in the case of liquid resin, the coating thickness of the resin is the height of the microlenses formed by curing, so in order to make many lenses uniform in height, when the resin is applied, the screen display surface is polished to ensure strict planar accuracy. Had to manage. This is because if the lens height becomes non-uniform, the front luminance and the viewing angle retention rate change, and the image becomes bright and dark, resulting in poor quality.

However, when the light transmission type light diffusing sheet 11 made of a photosensitive resin is used as in the present invention, the light diffusing sheet 11 is solid, so that the sheet should be formed in advance to a uniform thickness. Therefore, the screen display surface only needs to have smoothness to such a degree that the sheet can be attached, strict control of plane accuracy is unnecessary, and the manufacturing process can be further simplified.

Further, in the case of the present invention, since the light transmission type light diffusing sheet made of a photosensitive resin is solid, it is possible to make the angle easy to work without keeping the horizontal display surface as shown in FIG. A lens can be formed even when leaning or standing vertically.

As the adhesive for uniformly sticking the resin sheet on the entire display surface, a transparent adhesive resin can be applied, but a two-liquid type epoxy resin or an optical resin can be used. Solventless type adhesive resins such as curable resins are preferably used. That is, if the photosensitive resin sheet and the screen surface are not adhered so that air bubbles or solvent are not present, the formed microlens cannot be fixed to the optical fiber surface and uneven brightness occurs. To do.

A light transmission type light diffusion sheet made of a photosensitive resin attached to this display surface is exposed to light through an optical fiber,
The microlens 4 is formed by curing the resin around the fiber end face, and the lens diameter can be made larger than the optical fiber diameter as described above by adding the above-mentioned light diffusing agent, and the force for controlling it is applied. It depends on the energy of light. That is, it is preferable that one of the light irradiation intensity (W / m ² ) and the time (minute) is fixed and the other is adjusted to form a microlens.

At this time, since the light transmission type light diffusion sheet made of a photosensitive resin undergoes curing shrinkage due to exposure to light, the thickness T (μm) of the uncured resin sheet attached to the display surface is
It is necessary to set the target lens height H (μm) to about 1.1 times (T≈1.1H). T is 1.
If it is larger than 1H, the obtained microlens becomes too high and the luminance becomes low. On the contrary, if it is smaller than 1.1H, the luminance becomes high but the retention rate of the viewing angle luminance becomes low, which is not preferable.

The diameter of the optical fiber used for this purpose is generally in the range of 100 μm to 1,000 μm, and in consideration of the shape of the microlens necessary for diffusion, the light transmission type light diffusion sheet made of the above photosensitive resin is used. The thickness corresponds to the height H from the end face of the optical fiber to the top of the lens, and when the diameter of the optical fiber is d, H / d is set to 1/4 or more and 2 or less. It is in the range of 2,500 μm. Usually, optical fibers having a thickness of 400 to 750 μm are often used, and the thickness of the resin film is more preferably H / d of 1/2 to 3/2. Therefore, the sheet thickness is preferably about 200 μm to 1,125 μm.

Further, after the uncured portion is removed, the light diffusing layer formed to complete the curing can be irradiated again with light. The method uses light of the same type as that required for curing the microlens, for example, as shown in FIG.
The method of irradiating the screen surface from the position of 0 and the method of irradiating the incident surface from the position of the light source 9 may be performed simultaneously or one of them may be performed. When a photosensitive resin is used as an adhesive, the microlens thus formed has an increased adhesive force with an optical fiber, and the microlens itself has sufficient hardness.

After the formation of the microlens portion as described above, the resin in the uncured portion is dissolved and removed by brushing with water or warm water while maintaining the microlens shape of the cured portion. By removing the uncured portion by dissolution, the desired microlens 4 is formed on each end face of the optical fiber.

Further, the microlens 4 formed by removing the uncured portion is dried, and then the entire display surface is coated with a transparent waterproof resin to protect the microlens 4 with a coating layer of the waterproof resin. As a result, the microlenses made of the water-soluble photosensitive curable resin are not swollen with water and the light diffusion effect is not changed, and a display surface that can withstand practical use is formed. As described above, the water-resistant resin for the protective coat is preferably an acrylic polymer lacquer or an acrylic photocurable resin. As described above, it is more preferable to protect the display surface in the sheet state without forming the lens with an acrylic matte lacquer in order to enhance water resistance and suppress disturbance light reflection.

In the light transmitting type light diffusing sheet and the image display device according to the present invention having the above-mentioned structure, the light from the light source and the optical image are bright and can be seen uniformly over a wider angle. Particularly in an image display device, when an optical image is irradiated from a light source onto an image incident surface of an optical fiber bundle, individual pixels forming the image travel through the optical fibers and reach the emission end of the image display surface. To do. All the pixels emitted from the emission surface of the optical fiber pass through the light diffusion layer in the shape of a convex lens, are diffused, and are emitted. In particular, the light diffusion agent added and dispersed in the light diffusion layer is semitransparent,
More preferably, by using fine particles made of a transparent organic resin having a higher refractive index, the optical image formed on the image display surface has a bright and wide viewing angle, and an image formed by reflection of environmental disturbance light. It is possible to obtain a clear image with high resolution that does not make information difficult to recognize.

Further, since the solid sheet is used for forming the light diffusing layer, a large number of microlenses having a uniform height can be easily formed as the display surface as it is or in order to obtain the pear effect. It has become possible. In particular,
Since the solid sheet is composed of a photosensitive curable resin and a water-soluble resin in a non-photosensitive state, an image display device having extremely uniform quality and uniform quality can be efficiently manufactured.

[0072]

【Example】

Embodiments 1 and 2 In the image display device of FIGS. 1 to 4 described above, as the optical fiber 8, a diameter 40 having a core made of PMMA (refractive index 1.49) and a cladding made of fluorine resin (refractive index 1.41).
A 0 μm plastic optical fiber was used. The shape of the image entrance surface 2 was set to 146 mm in length × 205 mm in width, and the fibers were stacked in a dense bale-stacked state. The image display surface 3 has a fiber arrangement similar to that of the incident surface, and has a fiber pitch of 2 mm and a magnifying function of about 5 times.

The size of the image display surface 3 is 760 mm vertical × 1,000 mm wide, and the other portion 3a of the screen surface 3 other than the optical fiber is made of ABS resin. Cut each fiber together with ABS resin, and
The S resin surface was polished to obtain a smooth surface. On the other hand, as a light diffusing agent, 5 parts by weight of fine particles of a commercially available crosslinked polystyrene resin having an average particle diameter of 6 μm were added to the photosensitive resin composition to form a photosensitive resin sheet having a uniform thickness (400 μm). The refractive index of the crosslinked polystyrene resin was 1.59, and a resin containing alcohol-soluble copolymer nylon (water-insoluble) as a base polymer was used for the photosensitive resin composition. The refractive index of the resin separately measured by photo-curing was 1.51.

Next, the formed photosensitive resin sheet was preliminarily irradiated with ultraviolet rays on the entire surface in advance, and the entire sheet was photo-cured to prepare a light transmission type light diffusion sheet. A commercially available transparent epoxy resin was applied to and pasted on the smooth screen surface of the sheet which was previously polished. At the time of sticking, care was taken to prevent surface irregularities while pressing the diffusion sheet with a roller to remove air bubbles together with the adhesive epoxy.

In Example 2, the addition concentration of the crosslinked polystyrene fine particles as the diffusing agent was 3.5 parts by weight, and the sheet thickness was 55.
The one with 0 μm was used.

Although no lenses were formed in both Examples 1 and 2, since a light diffusing agent formed of a transparent resin was used, the images had high light transmittance and good contrast and excellent resolution. As shown in 1, the brightness and the viewing angle luminance were good. By the way, the luminance from the front (viewing angle 0 °) of Examples 1 and 2 is 312 cd /
m ² and 345 cd / m ² , and the viewing angles at which the brightness of these were 50% were both excellent at 25 °.

[0077]

[Table 1]

Examples 3 and 4 A resin containing water-soluble copolymer nylon as a base polymer was used in the photosensitive resin composition, and the addition concentration of crosslinked polystyrene fine particles as a light diffusing agent was 5.0% by weight in Example 3. In Example 4, it was 3.5% by weight. The cross-linked polystyrene resin had a refractive index of 1.59, and the water-soluble copolymer nylon resin had a refractive index of 1.52 after photosensitive curing.

The thickness of the photosensitive resin sheet formed with the above composition in the same manner as in Examples 1 and 2 was 350 μm in Example 3 and 510 μm in Example 4. The sheet was attached to the optical fiber screen surface in the same manner as in Examples 1 and 2.

Similar to Examples 1 and 2, excellent display performance was obtained as shown in Table 1, even though no lens was formed. However, in Examples 3 and 4, since the diffusion sheet was based on water-soluble copolymer nylon, it was photo-cured, but it swelled with water and was inferior in water resistance. Therefore, it was sprayed with an acrylic transparent matte lacquer. In addition to the water-repellent effect, the high visibility of the image that was not affected by the ambient light was obtained.

Comparative Examples 1 to 4 A light diffusing sheet was formed by changing the conditions, and a screen display surface was constructed in the same manner as in the above-mentioned examples. In each of the comparative examples, as shown in Table 2, the present invention was prepared. Since the requirements could not be completely satisfied, the front brightness was too low, or the brightness retention of the viewing angle was poor, and a satisfactory image could not be obtained.

[0082]

[Table 2]

Example 5 In the image display device of FIGS. 1 to 4 described above, as the optical fiber 8, a line in which the core is made of PMMA (refractive index 1.49) and the clad is made of fluorine resin (refractive index 1.41). Diameter 40
A 0 μm plastic optical fiber was used. The shape of the image incident surface 2 was 77 mm × 107 mm, and the optical fibers were stacked in a hexagonal close packed state. On the other hand, the image display surface 3 has a similar function of the arrangement of the optical fibers 8 and has a pitch of the optical fibers of 3 mm to provide a magnifying function of about 7 times. Therefore, the dimensions of the image display surface 3 were 581 mm × 783 mm.
ABS resin is used for the supporting plate 3a other than the optical fiber of the display surface 3.

The method for forming the image display surface 3 is as follows.
Was cut along with the surface of the support plate 3a, and the end face of the fiber was made uniform by polishing the support plate surface.

On the other hand, as a light diffusing agent, a crosslinked polystyrene resin powder having a particle size of 6 μm (Sekisui Plastics Co., Ltd.)
Techpolymer SBX-6) was added to the photosensitive resin composition in an amount of 5 parts by weight to form a photosensitive resin film having a uniform thickness (400 μm). The cross-linked polystyrene resin has a refractive index of 1.59, and a resin containing water-soluble copolymer nylon as a base polymer was used for the photosensitive resin composition. The refractive index of the resin separately measured by photo-curing was 1.52.

Next, a transparent epoxy resin (Araldite / Hardener manufactured by Ciba-Geigy Co., Ltd.) was applied to the previously polished smooth screen surface, and a photosensitive resin sheet formed by adding a diffusing agent as described above was formed. It was attached while pressing it with a roller to remove air bubbles. After the epoxy resin became semi-cured and the photosensitive resin sheet could be bonded, the high-pressure mercury lamp that had been adjusted and installed so that the UV illuminance on the image display surface was 1.6 W / m ² Irradiation was carried out for a minute to form a resin-cured portion to be a diffusion microlens around the end surface of the optical fiber on the image display surface.

After the irradiation, the epoxy resin was completely cured, and then the uncured portion of the photosensitive resin sheet was dissolved in warm water, removed, and dried. After drying, the screen surface was again irradiated with ultraviolet rays for 30 minutes to completely cure the convex lens on the image display surface to form a light diffusion layer.

The formed lens had a diameter of 954 μm and a height of 364 μm. In this example, the image obtained on the image display surface was a clear image having a high resolution and a wide viewing angle. By the way, the brightness at a viewing angle of 20 ° is
67% of the front luminance (148 cd / m ² ) could be maintained.
The refractive index is X (= 1.52) <Y (= 1.59),
The diffusing agent concentration was 5% by weight, H / d was 0.91, D / d was 2.4, D / L was 318, and T≈1.1H, which satisfied all the conditions.

Examples 6 and 7 Next, a polyvinyl alcohol resin was used in the photosensitive resin composition, and the concentration of the light diffusing agent added was 5% by weight (Example 6) and 8% by weight (Example 7). Formed a sheet of. Other than that, two kinds of image display surfaces were formed under exactly the same conditions as in Example 5.

As a result, the front luminance is 190 cd, respectively.
/ M ² , 117 cd / m ² , and the luminance retention rates against the front at a viewing angle of 20 ° were 60% and 83%, respectively.
The conditions and results of Examples 5 to 7 are shown in Tables 3 and 4 together with Comparative Examples.
Shown in.

Comparative Examples 5 to 10 Next, for comparison, those in which the refractive index of the light diffusing agent is smaller than that of the photosensitive resin, the concentration of the light diffusing agent, the lens height H and the lens diameter D are set in Examples 5 to 5. The value was set to a value different from that of No. 7, and other screens were formed in the same manner as in Examples 5 to 7 under other manufacturing conditions and manufacturing methods.

As is clear from Table 4, in each of Examples 5 to 7, there is a difference in the lens height H and the concentration of the light diffusing agent, but the front brightness and the front brightness retention rate have high values. .

On the other hand, in Comparative Example 5, the values of the lens height and the lens diameter are satisfied, but the refractive index of the light diffusing agent is low, and in Comparative Example 6, the lens which satisfies the conditions of the light diffusing agent is used. Since the height is low, the front-side luminance retention ratio at a viewing angle of 20 ° is extremely low, and it cannot be put to practical use.

In Comparative Example 7, since the concentration of the diffusing agent is low, the light diffusion is weak even when the photosensitive resin is cured by the irradiation of ultraviolet rays, so that the lens diameter cannot be increased and the front luminance is high but the viewing angle luminance is high. The retention rate was extremely low.

In Comparative Example 8, the irradiation time of ultraviolet rays from the incident surface was increased (20 minutes) to form a lens having a large diameter. As a result, not only the viewing angle luminance retention ratio became a little unsatisfactory value, but also The sharpness of the image disappeared and the image became poor quality. In Comparative Example 9, the height of the lens was high, and in Comparative Example 10, the concentration of the diffusing agent was too high. Therefore, although the front luminance and the viewing angle are different from each other when compared with the comparative example, it is found that the high luminance and the high viewing angle are obtained in Examples 5 to 7.

[0096]

[Table 3]

[0097]

[Table 4]

Example 8 In the image display device shown in FIGS. 1 to 4 described above, as the optical fiber 8, the diameter is such that the core is made of PMMA (refractive index 1.49) and the clad is made of fluorine resin (refractive index 1.41). 40
A 0 μm plastic optical fiber was used. The shape of the image entrance surface 2 was 146 mm vertical × 205 mm wide, and the fibers were stacked in a hexagonal close packed state. The image display surface 3 has a fiber array similar to the incident surface, and the fiber pitch is 2
As a mm interval, it has a magnifying function of about 5 times.

The size of the image display surface 3 is 760 mm vertically × 1,000 mm wide, and the portion 3a other than the optical fiber of the screen surface 3 is made of ABS resin. Cut each fiber together with ABS resin, and
The S resin surface was polished to obtain a smooth surface. On the other hand, alumina powder having an average particle diameter of 5 μm was added to the 3.5 wt% photosensitive resin composition as a light diffusing agent to form a photosensitive resin sheet having a thickness of 400 μm.

A transparent epoxy resin (Araldite / Hardener manufactured by Nippon Ciba-Geigy Co., Ltd.) was applied to the surface of the screen that had been polished before, and the sheet was attached while removing air bubbles with a roller. After the epoxy resin has hardened, the high-pressure mercury lamp, which has been adjusted and installed so that the UV illuminance on the display surface is 2.3 W / m ^2, is irradiated from the incident surface for 3.5 minutes. A resin-cured portion to be a diffusion microlens was formed on the.

After the irradiation, the uncured portion of the photosensitive resin sheet is washed with water, dissolved and removed, and dried, and then ultraviolet rays are irradiated again toward the screen surface for 30 minutes to complete the curing of the diffusion microlens which becomes the display surface. It was The obtained microlens had a button shape, and the diameter of the lens was 950 μm.
The height was 390 μm. An acrylic transparent lacquer was spray coated on the entire display surface including these lenses to form a water resistant protective film.

In the present example, the image obtained on the image display surface had a high resolution and was a clear image. The retention of the luminance at the viewing angle was high, and 60% of the front luminance (385 cd / m ² ) could be retained at the viewing angle of 20 °. The results are shown in Table 5 together with the comparative examples.

Examples 9 and 10, Comparative Examples 11 to 14 Microlenses were prepared and evaluated in the same manner as in Example 8 except that the conditions were changed. 10) Both high frontal luminance and high frontal luminance retention were obtained, but those that did not (Comparative Example 1
1 to 14), one of the characteristics was inferior. The results are shown in Tables 5 and 6.

[0104]

[Table 5]

[0105]

[Table 6]

[0106]

As described above, according to the image display device and the method of manufacturing the same of the present invention, high brightness can be obtained in a wide viewing angle range. That is, since the light transmission type light diffusion sheet is obtained, the directivity of light can be suppressed, and the viewing angle can be widened while maintaining high brightness (brightness). In particular, on the image display surface viewed by a large number of people at once such as a large screen, the above effects play a very important role.

However, when the light transmission type light diffusion sheet of the present invention is not used, for example, when alumina is used as the diffusing agent, the light reflection type light diffusion sheet is obtained. In this case,
When the sheet is used as an image display surface, the front brightness is lowered, probably because the light energy efficiency is lowered due to the light reflection type. Further, the reflected and scattered light makes the entire screen whitish and the image contrast deteriorates. In order to prevent this drawback, an ideal microlens shape can be formed by forming the light diffusion layer as a convex lens island.

Further, from these results, even if the light transmitting type light diffusing sheet is used, in order to eliminate the influence of the ambient disturbance light, the light transmitting type light diffusing sheet made of the photosensitive resin is used to form the microlenses. It became clear that doing it was more effective.

Particularly, as a method of manufacturing a display device capable of obtaining uniform brightness over the entire large-sized display surface, a method of forming a lens using a liquid photosensitive curable resin as in the conventional method is difficult. The curable light-transmitting type light diffusing sheet is very simple and efficient because a light diffusing layer having a certain height can be obtained from a sheet having a certain thickness.

[Brief description of drawings]

FIG. 1 is a perspective view of an image display device according to an embodiment of the present invention.

FIG. 2 is an enlarged front view of one end surface of an optical fiber on the screen surface of the apparatus of FIG.

FIG. 3 is a sectional view taken along line XX of FIG.

FIG. 4 is a schematic configuration diagram showing a method for manufacturing an image display device according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber bundle 2 Image entrance surface 3 Image display surface (Screen surface) 4 Light diffusing layer (microlens) 5 Cured photosensitive resin 6 Light diffusing agent 7 Cut end face of optical fiber 8 Optical fiber 9, 10 Light source 11 Photosensitivity Resin sheet 12 Support stand

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigetora Kashio 1-1-1, Sonoeyama, Otsu City, Shiga Toray Co., Ltd. Shiga Plant

Claims (26)

[Claims] 1. A light transmissive light diffusing sheet containing a light diffusing agent which is fine particles of a transparent or semi-transparent organic resin, wherein (a) the resin forming the light diffusing sheet is transparent or semi-transparent. And the refractive index of the organic resin forming the light diffusing agent fine particles is Y, X <Y, and (b) the light diffusing agent fine particles. The light-transmissive light diffusing sheet, wherein the concentration added to the resin forming the light diffusing sheet is 1% by weight or more and 15% by weight or less. 2. The thickness of the light diffusion sheet is T (μm),
When the addition concentration of the light diffusing agent fine particles to the resin forming the light diffusing sheet is C (wt%), 500 ≦ T ×
The light transmission type light diffusion sheet according to claim 1, which satisfies C ≦ 5000. 3. The light transmission type light diffusion sheet according to claim 1, wherein the light diffusion sheet is formed of a photosensitive resin, and the resin is water-soluble or alcohol-soluble in an uncured state. 4. An image display device in which one end surface and the other end surface of a large number of optical fibers are arranged on an image display surface and an image entrance surface, respectively, and the image display surface has a transparent or semitransparent organic system. A light transmission type light diffusing sheet containing a light diffusing agent which is fine particles of a resin, wherein (a) the resin forming the light diffusing sheet is made of a transparent or semitransparent organic resin and has a refractive index of X When the refractive index of the organic resin forming the light diffusing agent fine particles is Y, X <Y, and (b) the addition concentration of the light diffusing agent fine particles to the resin forming the light diffusing sheet is An image display device comprising a light diffusion layer formed of a light transmission type light diffusion sheet of 1% by weight or more and 15% by weight or less. 5. An image display device in which one end surface and the other end surface of a large number of optical fibers are respectively arranged on an image display surface and an image incident surface, and the image display surface has an end portion of each optical fiber. A large number of light diffusion layers formed of a photocurable photosensitive resin are distributed as button-shaped islands, and
The button-shaped island is formed as a microlens having a large number of particulate light diffusing agents added therein. 6. The image display device according to claim 5, wherein the button-shaped island is formed as a convex lens-shaped island. 7. The image display device according to claim 6, wherein the convex lens-shaped islands are continuous with each other. 8. The image display device according to claim 4, wherein the surface of the light diffusion layer is protectively coated with a water resistant resin. 9. The water resistant resin is an acrylic polymer lacquer or an acrylic photocurable resin.
Image display device. 10. The image display device according to claim 5, wherein the photosensitive resin is a water-soluble or alcohol-soluble sheet in an uncured state. 11. The image display device according to claim 10, wherein the water-soluble or alcohol-soluble photosensitive resin comprises a resin composition containing polyvinyl alcohol or polyamide as a main component. 12. An image display device in which one end surface and the other end surface of an optical fiber bundle in which a large number of optical fibers are bundled are arranged on an image display surface of an optical image and an image incident surface, respectively. B) On the image display surface, a large number of light diffusion layers made of transparent or semitransparent photocurable photosensitive resin formed at the end of each optical fiber are dispersed as convex lens-like islands. The photosensitive resin contains a light diffusing agent that is fine particles of a transparent or semitransparent organic resin, and the refractive index of the photosensitive resin is X and the refractive index of the organic resin that is the light diffusing agent is Y. Then, X <Y, and (b) the concentration of the light diffusing agent added to the photosensitive resin is 1% by weight or more and 1 or more.
An image display device characterized by being 5% by weight or less. 13. When the height of the convex lens is H (μm) and the diameter of the optical fiber is d (μm), 1/4 ≦ H
/ D ≦ 2, and the diameter of the skirt of the convex lens is D (μm), and the pitch of the array of optical fibers on the image display surface is L (mm), 1.1 ≦ D / d, D /
The image display device according to claim 5, wherein L ≦ 750 is satisfied. 14. A plurality of optical fibers are arranged in such a manner that one end surface of each of the optical fibers is flattened on the image display surface, and then fine particles of a transparent or semitransparent organic resin are provided on the image display surface. Which is a light transmissive light diffusing sheet containing a light diffusing agent, wherein (a) the resin forming the light diffusing sheet is made of a transparent or semitransparent organic resin, the refractive index of which is X, When the refractive index of the organic resin forming the light diffusing agent fine particles is Y, X <Y, and (b)
A method of manufacturing an image display device, comprising: adhering a light transmission type light diffusion sheet having an addition concentration of the light diffusion agent fine particles of 1% by weight or more and 15% by weight or less to a resin forming the light diffusion sheet. 15. A plurality of optical fibers are arranged so that one end surfaces thereof are aligned so that they are flat on the image display surface, and then the image display surface is covered with a water-soluble or alcohol-soluble photosensitive resin. Attach the light transmission type light diffusion sheet
Next, the other end surface of the optical fiber is irradiated with light, and the irradiated light is emitted from the one end surface, whereby the photosensitive resin located around the one end surface of the optical fiber on the image display surface is reactively cured. And a method for manufacturing an image display device. 16. Before a light diffusing sheet is attached to the image display surface, a uniform bottom surface is adjusted so that a part of the sheet layer or all layers are exposed in advance from the side to be the attachment surface of the light diffusing sheet. The method for manufacturing an image display device according to claim 15, wherein light irradiation is performed. 17. The method for producing an image display device according to claim 15, wherein after the photosensitive resin around the one end surface of the optical fiber is reactively cured, the uncured portion is dissolved and removed with water or warm water. 18. A part or front part of the uncured part of the photosensitive resin is dissolved and removed with water or warm water and dried, and then the entire image display surface is irradiated with light to completely cure the photosensitive resin. The method for manufacturing an image display device according to claim 17, wherein the image display device is manufactured. 19. The method of manufacturing an image display device according to claim 15, wherein the light transmission type light diffusion sheet made of the photosensitive resin contains a particulate light diffusion agent. 20. The light diffusing agent is made of an organic resin.
A method of manufacturing an image display device according to claim 19. 21. The method of manufacturing an image display device according to claim 19, wherein a refractive index of the light diffusing agent is higher than a refractive index of the photosensitive resin. 22. The substantially transparent photosensitive resin is used as an adhesive when the light transmission type light diffusing sheet made of the photosensitive resin is attached to an image display surface. Of manufacturing image display device of. 23. The method of manufacturing an image display device according to claim 22, wherein a substantially transparent epoxy resin is used as the adhesive. 24. The image according to claim 23, wherein the light diffusion sheet is exposed to light in a semi-cured state of the epoxy resin to completely cure the epoxy resin, and then an uncured portion of the light diffusion sheet is washed and removed. Manufacturing method of display device. 25. The image display device according to claim 17, wherein each of the cured photosensitive resin portions after the uncured portion is dissolved and removed is formed into a convex lens shape. Method. 26. When the thickness of the light transmission type light diffusion sheet made of the photosensitive resin is T (μm) and the target height of the convex lens is H (μm), T≈1.1H, A method of manufacturing an image display device according to claim 25.