JP2005088414A - Manufacturing method for lens sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method which enables efficient manufacture of a lens sheet composed of a lens sheet substrate and a light diffusion sheet. <P>SOLUTION: A diffusion layer, which is constituted by dispersing light diffusion particulates in an optically transparent resin, is formed on one side of a continuously fed optically-transparent sheet, so that the light diffusion sheet can be manufactured. Subsequently, the lens sheet, wherein lens parts are laminated and formed, is manufactured on the other side of the diffusion layer of the continuously fed light-diffusion sheet. After that, the continuously fed lens sheet is cut in a direction (width direction) perpendicular to a feeding direction, and the feeding direction, so that the lens sheet of a predetermined size can be obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention can efficiently manufacture a lens sheet suitable for constructing a transmissive screen (hereinafter sometimes referred to as a rear projection screen, a transmissive projection screen, etc., but these are all synonymous). The present invention relates to a method for manufacturing a lens sheet.

In a rear projection television equipped with a transmissive screen, image light projected from a projector having a light source, an image display body, and a projection lens passes through a Fresnel lens sheet having a Fresnel lens and a lenticular sheet having a cylindrical lens group. Configured to reach the observer.
In recent years, as a projector, in place of a three-tube (R, G, B) CRT projector, a liquid crystal projector or a registered trademark “DMD (digital micromirror mirror)” of TI (Texas Instruments), Inc. Display devices using single-tube projectors based on the reflective light valve system called “devices” or DLP (Digital Light Processing) ”have become widespread, and rear projection screens suitable for these new devices are available. It is requested.
Since the screen for the above device has few problems of color shift, it is not necessary to have a cylindrical lens group on the front and back of the lenticular sheet, and a structure having a lens portion only on one side is sufficient. As the number of pixels increases, the demand for finer unit lenses and finer array pitches increases.
A transmissive or reflective television set such as an LCD or DMD has a single light source, a small light source of about 1 to 3 inches, and a small projection lens pupil diameter.
Therefore, even if the light source light is diffused by the light diffusing fine particles mixed in the screen, the luminance unevenness of the emitted light is difficult to be mitigated, and a scintillation phenomenon is likely to occur.
In order to weaken the scintillation phenomenon, a large amount of various light diffusing fine particles are mixed in the screen, and the layer containing the light diffusing fine particles (light diffusing layer) is localized in two layers. For example, a method of artificially increasing the pupil diameter is employed, and an improvement in the light diffusion layer is also required for these new devices.
Projection television screens are generally required to have an optical function of diffusing widely in the horizontal direction and diffusing narrower than the horizontal direction in the vertical direction. The diffusion in the vertical direction is often required for a light diffusing plate or a light diffusing sheet in which a light diffusing agent is dispersed.
In recent rear projection televisions, there is a high demand for a light diffusive screen capable of observing images with good resolution and bright images with the same chromaticity in a wide range.
In particular, with the appearance of a light source with high brightness, bright images with the same chromaticity can be observed over a wide range. As a result, there is a demand for a manufacturing method that can efficiently manufacture a lens sheet that enables observation of an image with good resolution, such as a thinner light diffusion portion.
In the past, it has been common to produce a lens sheet substrate and a light diffusive sheet, and integrate them via an adhesive layer to obtain a lens sheet having light diffusion. Thus, after manufacturing the lens sheet substrate and the light diffusing sheet, each of them is stored, and these members are supplied and bonded together in a separate process, so the number of processes is increased and the production is not efficient. It was. (See Patent Document 1)
Japanese Patent Laid-Open No. 10-83029.

An object of this invention is to provide the manufacturing method which can manufacture efficiently the lens sheet which consists of a lens sheet base material and a light diffusable sheet.

The method for producing a lens sheet according to the present invention includes:
A light diffusive sheet is produced by forming a diffusion layer formed by dispersing light diffusing fine particles in a light transmissive resin on one side of a continuously supplied light transmissive sheet,
Next, on the side opposite to the diffusion layer of the light diffusive sheet that is continuously supplied, a lens sheet is formed by laminating and forming a lens part,
Next, the lens sheet that is continuously supplied is cut in the direction perpendicular to the supply direction (width direction) and the supply direction to obtain a lens sheet of a predetermined size.
As a means for forming the diffusion layer, it is preferable to use a diffusion ink formed by dispersing light diffusing fine particles in a light transmissive resin.
Moreover, there are a plurality of locations where the diffusion ink is applied and formed on one side of the light transmissive sheet in the direction of supply of the light transmissive sheet,
It is also effective from the viewpoint of scintillation to use diffusion inks having different compositions at each coating formation location.

According to the present invention, since the light-diffusing sheet and the lens sheet are manufactured in a separate process and bonded to each other in a predetermined size, a necessary margin is not required, so the sheets are continuously pasted as they are. In addition, since the predetermined size can be obtained, the sheet can be used effectively.

Embodiments of the present invention will be described.
FIG. 1 is an explanatory view showing an example of the production method of the present invention.
A light transmissive sheet 11 is continuously supplied from the first paper supply unit 1, and a diffusion layer 13 containing light diffusing fine particles in a light transmissive resin is provided on one side of the light transmissive sheet 11 using a T die 3. To form a continuous light diffusing sheet 15.
Next, a lens sheet base material 17 having a lens portion that is continuously supplied from the second paper feeding unit 2 on the surface of the light transmissive sheet 11 (on the side opposite to the diffusion layer 13) of the continuous light diffusing sheet 15. By cutting the both ends (in the width direction with respect to the supply direction) of the continuous lens sheet 20 laminated together by cutting at the ear picking portion 40 to a predetermined width, the cutting portion 30 is cut to a predetermined length, A lens sheet 50 having a predetermined size is manufactured.
In addition, as shown in FIG. 2, a light transmissive sheet 11 is continuously supplied from the first paper feeding unit 1, and a T-die 3 is used on one side of the light transmissive sheet 11 to form a light transmissive resin. A diffusion layer 13 containing light diffusing fine particles is applied and formed, and immediately thereafter, a light transmissive layer 14 containing no light diffusing fine particles is applied and formed on a light transmissive resin using a T die 4. The continuous light diffusing sheet 15 having two light diffusing layers having different characteristics (in this embodiment, the second light diffusing layer is related to the case where there is no light diffusing characteristic) is manufactured.
Next, both ends of the continuous lens sheet 20 in which the lens sheet base material 17 having a lens portion is bonded and laminated on the surface of the light transmissive sheet 11 of the continuous light diffusing sheet 15 are cut by the ear picking portion 40. After the predetermined width, the cutting part 30 is cut into a predetermined length to manufacture a lens sheet 50 having a predetermined size.
The lens unit is selected from any of a lenticular lens in which cylindrical lenses are arranged in parallel in one direction, a microlens in which unit lenses are arranged two-dimensionally, and a cross lenticular lens in which cylindrical lenses are arranged in parallel in a plurality of directions. .
The means for bonding the continuous light diffusing sheet 15 and the lens sheet base material 17 is that the bonding is performed through the adhesive material layer, and no new large pressure or heat is applied at the time of bonding. This is preferable because the performance is maintained as it is.
Here, the material which comprises the light diffusable sheet | seat 15 of this invention is demonstrated.
First, the light transmissive sheet 11 is generally a plastic material, and examples thereof include polyethylene, polypropylene, polyethylene terephthalate, triacetyl cellulose, polystyrene, polyvinyl chloride, polyacryl, polycarbonate, and polyurethane. And the surface is surface-treated by corona treatment, anchor treatment, etc., and the adhesiveness of a diffusion layer is improved.
The diffusion layer 13 is basically composed of light diffusing fine particles and a light transmissive resin, and the refractive index difference between these ranges is 0.001 to 0.2, preferably 0.01 to 0.1. By setting the range, stray light can be reduced, generation of scintillation can be suppressed, and a bright image can be obtained.
If the difference in refractive index between the light diffusing fine particles forming the diffusion layer 13 and the light transmitting resin is less than 0.001, a very effective diffusion effect cannot be obtained, and when used as a screen as a whole, Brightness cannot be maintained over a wide range, and intense light concentrates in the center of the screen, so that hot bars and scintillation due to the hot bars are observed.
On the other hand, if it exceeds 0.2, stray light increases on the entire screen as the incident angle increases, and scintillation is observed. Furthermore, an excessive diffusion effect is produced, the brightness of the screen is dispersed, and the whole becomes dark.
The light diffusing fine particles used for the diffusion layer 13 are in the range of 1 to 30 μm, preferably in the range of 5 to 20 μm, and the average particle diameter by the laser diffraction scattering method is 6 μm or less, preferably 5 μm or less. By being in this range, the dispersibility in the resin is good and a uniform light diffusion effect can be obtained.
The light diffusing fine particles are preferably spherical, particularly pearly. The light diffusing fine particles may be made of an organic polymer such as an acrylic resin, a polyurethane resin, or a polyamide resin, or an inorganic compound such as silica.
The diffusion layer 13 has an addition amount of light diffusing fine particles in the range of 5 to 40% by weight of the whole, so that the light diffusibility and the image visibility can be secured, and a good light diffusive sheet is obtained. It is done.
Further, the diffusion layer 13 has a thickness in the range of 10 to 2000 μm.

On one side of a continuous light-transmitting sheet made of an acrylic resin sheet having a thickness of 500 μm, 25% by weight of light-diffusing fine particles made of an acrylic resin having an average particle diameter of 10 μm is dispersed in a light-transmitting resin made of an epoxy resin. The applied coating solution was applied to a thickness of 80 μm to form a diffusion layer, and a continuous light diffusing sheet was produced.
Next, a continuous lenticular lens sheet substrate was bonded to the surface of the continuous light transmissive sheet via an adhesive layer to obtain a continuous lens sheet. This continuous lens sheet was first cut into a 40-inch width at both ends, and then cut so that the length direction matched to 40 inches to obtain a 40-inch lens sheet.
The difference in refractive index between the light-transmitting resin forming the diffusion layer and the light-diffusing fine particles was 0.05.

On one side of a continuous light-transmitting sheet made of an acrylic resin sheet having a thickness of 500 μm, 25% by weight of light-diffusing fine particles made of an acrylic resin having an average particle diameter of 10 μm is dispersed in a light-transmitting resin made of an epoxy resin. The thickness of the first coating liquid is 50 μm, and the second coating liquid made of a light-transmitting resin made of epoxy resin is added to the first coating liquid so that the thickness is 50 μm. This was applied to form a diffusion layer, and a continuous light diffusing sheet was produced.
Next, a continuous lenticular lens sheet substrate was bonded to the surface of the continuous light transmissive sheet via an adhesive layer to obtain a continuous lens sheet. This continuous lens sheet was first cut into a 40-inch width at both ends, and then cut so that the length direction matched to 40 inches to obtain a 40-inch lens sheet.
The difference in refractive index between the light-transmitting resin forming the diffusion layer and the light-diffusing fine particles was 0.05.

Explanatory drawing which shows an example of the manufacturing method of the lens sheet of this invention. Explanatory drawing which shows the other example of the manufacturing method of the lens sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ......... Light transmissive sheet | seat 13 ......... Diffusion layer 14 ......... Light transmissive layer 15 ......... Light diffusive sheet 17 ......... Lens sheet base material 20 ......... Continuous lens sheet 30 ......... Cutting unit 40... Ear picking unit 50.

Claims (9)

A light diffusive sheet is produced by forming a diffusion layer formed by dispersing light diffusing fine particles in a light transmissive resin on one side of a continuously supplied light transmissive sheet,
Next, on the side opposite to the diffusion layer of the light diffusive sheet that is continuously supplied, a lens sheet is formed by laminating and forming a lens part,
Next, the lens sheet that is continuously supplied is cut in a direction perpendicular to the supply direction (width direction) and the supply direction to obtain a lens sheet of a predetermined size. 2. The method for producing a lens sheet according to claim 1, wherein the means for forming the diffusion layer is by applying a diffusion ink in which light diffusing fine particles are dispersed in a light transmissive resin. There are a plurality of locations where the diffusion ink is applied and formed on one side of the light transmissive sheet in the direction of supply of the light transmissive sheet,
The method for producing a lens sheet according to claim 2, wherein diffusion inks having different compositions are used at the respective coating formation locations. The lens portion is laminated by continuously supplying a lens sheet base material in which a lens portion is formed on one surface of a base material sheet, and is performed via an adhesive layer on the side opposite to the lens portion. The manufacturing method of the lens sheet in any one of Claims 1-3. The lens unit is any one selected from a lenticular lens in which cylindrical lenses are arranged in parallel in one direction, a micro lens in which unit lenses are arranged two-dimensionally, and a cross lenticular lens in which cylindrical lenses are arranged in parallel in a plurality of directions. The manufacturing method of the lens sheet in any one of Claims 1-4 characterized by the above-mentioned. 6. The lens sheet according to claim 1, wherein the diffusion layer has a refractive index difference between the light diffusing fine particles and the light transmissive resin in the range of 0.001 to 0.2. Production method. 7. The light diffusing fine particles used for the diffusion layer have a particle size in the range of 1 to 30 [mu] m, and an average particle size by laser diffraction scattering method is 6 [mu] m or less. The manufacturing method of the lens sheet of description. The method for producing a lens sheet according to any one of claims 1 to 7, wherein the addition amount of the light diffusing fine particles in the diffusion layer is in the range of 5 to 40% by weight of the whole. The method for producing a lens sheet according to claim 1, wherein the diffusion layer has a thickness in the range of 10 to 2000 μm.