JPH05127258A - Transmission type screen - Google Patents

Abstract

PURPOSE:To provide the transmission type screen which has a sufficient diffusing property while preventing the wear and chipping in the peak parts of Fresnel lenses by rubbing of a Fresnel lens sheet and a lenticular lens sheet against each other and decreasing the light loss by a diffusing agent and the deterioration in image quality as the transmission type screen constituted by combining these lens sheets and adding the diffusing agent to the lenticular lens sheet to improve the diffusion property. CONSTITUTION:The lenticular lens sheet 3 has the surface hardness smaller than the surface hardness of the Fresnel lens sheet 2 and org. resin beads consisting of a resin formed by crosslinking a resin for the lenticular lens sheet or the resin denatured from the resin for the lenticular lens sheet are kneaded as the light diffusing agent into the lenticular lens sheet 3, by which the transmission type screen 1 is constituted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention comprises a combination of a Fresnel lens sheet and a lenticular lens sheet,
The present invention relates to a transmissive screen used for a projection television or the like.

[0002]

2. Description of the Related Art The performance required for a transmissive screen is
It is bright and visible from everywhere. Therefore, a circular Fresnel lens sheet for converting diffused light from a light source such as a CRT into parallel light and a separate lenticular lens sheet for effectively utilizing a certain amount of light are combined, and the Fresnel lens sheet The transmissive screen, which is a combination of the Fresnel lens surface and the lenticular surface of the lenticular lens sheet facing each other, has high light transmittance and sufficient brightness of the screen surface so that the light source cannot be seen directly from the viewer side. It has a high light diffusivity and is used as a high resolution image for giving a fine image. or,
In order to improve the light diffusivity of the transmissive screen, glass powder, inorganic fine powder such as alumina and silica have been conventionally added as a diffusing agent to a resin forming a lenticular lens. However, when the lenticular lens surface of the lenticular lens sheet and the Fresnel lens surface having a sharp surface are set to face each other to form a transmissive screen, when the two lens sheets are rubbed during transportation, the above-mentioned inorganic The system-type diffusing agent has poor wettability with the resin, and the diffusing agent appears on the surface of the lenticular lens, so that there is a problem that the surface of the Fresnel lens is scraped by the diffusing agent and the image quality deteriorates.

Further, in order to improve the light diffusion of the transmissive screen, for example, 1) using organic resin beads as a diffusing agent as shown in JP-A-1-269901 and 2) JP-A-1- As disclosed in Japanese Patent No. 229238, a lenticular lens sheet in which a resin containing a rubber-like polymer and a diffusing agent are mixed has been proposed.

[Problems to be Solved by the Invention]

However, although the lenticular lens sheet of the above 1) is capable of imparting an appropriate fogging property and preventing the generation of hot spots, the surface of the Fresnel lens when combined with the Fresnel lens sheet is It was difficult to prevent scraping. See also 2)
Although the lenticular lens sheet of 1 has a good resolution without cracks during molding and has a bright screen and a rigid screen, the Fresnel surface of the lenticular lens sheet when set with the Fresnel lens sheet is the same as the lens sheet of 1) above. It didn't solve the problem that was cut.

The present invention solves the above-mentioned drawbacks of the prior art. In a transmission screen obtained by combining a Fresnel lens sheet and a lenticular lens sheet and adding a diffusing agent to the lenticular lens sheet to improve the diffusivity. An object of the present invention is to provide a transmissive screen that has sufficient diffusivity while preventing abrasion and chipping of the Fresnel lens top portion due to rubbing between lens sheets and reducing light loss and image quality deterioration due to a diffusing agent.

[Means for Solving the Problems]

The transmissive screen of the present invention is a transmissive screen comprising a Fresnel lens surface of a Fresnel lens sheet and a lenticular lens surface of a lenticular lens sheet provided with light-shielding printing convex portions on the back surface thereof, which face each other.
The lenticular lens sheet has a surface hardness smaller than the surface hardness of the Fresnel lens sheet, and the resin for the lenticular lens sheet or a resin obtained by modifying the resin for the lenticular lens sheet as a light diffuser is cross-linked to the lenticular lens sheet. It is characterized by kneading organic resin beads. Further, in the above transmissive screen, the difference in refractive index between the organic resin beads and the resin for the lenticular lens sheet is 0.005 to 0.
The range of 05 is preferable. Further, in the transmission screen, the lenticular lens sheet is manufactured by extrusion molding of a resin containing rubber, and at least the lenticular lens surface is released from the lenticular lens mold at a temperature equal to or higher than the heat deformation temperature of the resin for the lenticular lens. It is preferable that the curvature of the convex portion due to the organic resin beads protruding on the surface of the lenticular lens is smaller than that of the organic resin beads.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an external perspective view showing an example of the transmission screen of the present invention.

The transmissive screen 1 of the present invention is the transmissive screen 1 in which the Fresnel lens surface 4 of the Fresnel lens sheet 2 and the lenticular lens surface 6 of the lenticular lens sheet 3 are opposed to each other, and the lenticular lens sheet 3 is the Fresnel lens sheet. 2 having a surface hardness smaller than the surface hardness of 2 and kneading the lenticular lens sheet 3 with a resin for the lenticular lens sheet or a crosslinked resin obtained by modifying the resin for the lenticular lens sheet as a light diffusing agent. It is The light-shielding printing convex portion 5 is provided on a portion corresponding to the non-light-collecting surface of the lenticular lens, and light-shielding printing is performed. Since the surface hardness of the Fresnel lens sheet 2 is larger than the surface hardness of the lenticular lens sheet 3, there is no possibility that the Fresnel lens surface is scraped and the Fresnel lens top is chipped.

The material of the Fresnel lens sheet 2 and the lenticular lens sheet 3 used in the transmissive screen 1 of the present invention is not particularly limited as long as it is a light transmissive transparent resin. For example, acrylic resin, styrene resin, polycarbonate, A vinyl chloride resin or the like is used, and among the above resins, an acrylic resin is preferable because it has good surface scratch resistance, weather resistance, transparency, and the like. Examples of the acrylic resin include a resin mainly containing methyl methacrylate, and a homopolymer of methyl methacrylate or methyl methacrylate and methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, acrylonitrile, anhydrous. Also included are copolymers with one or more of maleic acid, styrene or α-methylstyrene, or mixtures of methyl methacrylate homopolymers with the above copolymers.

Particularly, as the resin for the lenticular lens, an acrylic resin to which rubber is added is preferable because it has a good mold return property described later. The above rubber is a natural or synthetic rubber-like polymer that exhibits elasticity at room temperature,
Natural rubber or synthetic rubber is used. For example, natural rubber and butadiene, diene rubber obtained by polymerizing or copolymerizing a diene monomer such as isoprene, saturated rubber such as acrylic rubber, ethylene-propylene rubber, acrylic graft copolymer, and the above diene rubber and styrene. Random or block copolymers with vinyl monomers such as The addition amount of the above rubber is preferably 1 to 5% by weight with respect to the acrylic resin of the lenticular lens. If the addition amount is less than 1% by weight, the impact resistance is not sufficiently improved, and the addition amount is 5% by weight. If it exceeds, the image may become turbid.

The organic resin beads added to the lenticular lens sheet as a light diffusing agent in the present invention may be the same resin as the resin for the lenticular lens sheet, or a resin obtained by modifying the resin. As a modified resin for the lenticular lens sheet,
Examples thereof include those obtained by modifying the acrylic resin, styrene resin, polycarbonate, vinyl chloride resin and the like shown above. Particularly preferable organic resin beads are crosslinked resin beads obtained by polymerizing a non-crosslinked polymer obtained by copolymerizing an alkyl methacrylate, an aromatic vinyl monomer and an alkyl acrylate and a crosslinkable monomer.
The average particle size of the organic resin beads is preferably 10 to 70 μm, and the addition amount to the lenticular lens sheet 3 is 2 with respect to 100 parts by weight of the resin for the lenticular lens sheet.
-30 parts by weight is preferred. In particular, organic resin beads have a refractive index difference of 0.00 with the resin for the lenticular lens sheet.
It is preferably in the range of 5 to 0.05. If this refractive index difference is less than 0.01, it is necessary to add a large amount of expensive diffusing agent to obtain the necessary diffusion angle, and if the amount of diffusing agent added is increased too much, the surface irregularities due to the diffusing agent will become tight. There is a risk of becoming. On the other hand, if the difference in refractive index is larger than 0.05, the reflectance at the interface between the diffusing agent and the resin becomes high, and as a result, the contrast of the entire screen may be lowered.

In the present invention, the Fresnel lens sheet and the lenticular lens sheet may be produced by any of ordinary injection molding method, compression molding method, extrusion method, casting method, continuous casting method, ultraviolet curing method and the like. However, the lenticular lens sheet 3 is preferably manufactured by extrusion molding as described below. FIG. 2 is a schematic view showing an example of manufacturing a lenticular lens sheet by an extrusion method.

As shown in FIG. 2, the lenticular lens sheet 3 has a first roll 12 having a lenticular lens mold 11 for the resin 9 extruded from the extruder 10 and a first roll 12 having a light-shielding convex mold 13. It is sandwiched between the two rolls 14 to form the shape of the lenticular lens surface 6 and the shape of the light-shielding printing convex portion 5. At this time, although not shown, the lenticular lens mold 11 is provided on the second roll 14, the light-shielding printing convex mold is provided on the first roll 12, and the mold 11 is released from the mold 11 at a temperature equal to or lower than the thermal softening point of the resin. It can also be molded. When molded in this way,
The lenticular lens surface is flat without the mold returning and the diffusing agent does not project to the surface, and it is effective against rubbing with the Fresnel lens sheet, but the release point 16 from the first roll 12 When the mold is released at a temperature below the softening point of the resin, the shape of the convex surface for light-shielding printing on the opposite side that is not in contact with the roll causes mold reversion, so that the edges of the convex portions become uneven, and the light-shielding layer May be difficult to print uniformly, and unevenness is likely to occur. Incidentally, the cause of the above mold reversion is that the micro state of the polymer is stabilized like a yarn ball at the softening temperature or lower, but the yarn is unraveled and stretched when heated and molded. This is because it tries to return to the original shape of the yarn, and it seems to be greatly influenced by the thermal expansion coefficient and viscoelasticity of the resin.

Therefore, as shown in FIG. 2, the extruded resin 9 is shaped by the first roll 12 and the second roll 14, and then the third roll 15 is sandwiched between the second roll 14 and the second roll 14.
At the mold release point 16 of the first roll at a temperature not lower than the heat deformation temperature of the resin, the lenticular lens mold 11
Release more. In this case, since the lenticular lens surface 6 is not pressed, the resin returns to the mold. In this case, a resin having a large mold reversion, that is, a resin obtained by adding rubber to the above acrylic resin is preferable so that the mold reversion easily occurs. In the above case, the lenticular lens surface 6
Since the mold reversion occurs, there is no risk that the diffusing agent will be dragged into the resin as the resin shrinks and project onto the surface of the lens surface 6, and the surface of the lenticular lens surface 6 will have a convex portion due to the resin beads. Also, the curvature of the resin beads is smaller than that of the resin beads, and even if the resin beads are rubbed against the Fresnel lens sheet, there is no risk of damaging the Fresnel lens surface 4. In the above method, mold reversion occurs on the surface of the lenticular lens and the diffusivity is reduced, but the amount of the reduction can be sufficiently dealt with by increasing the amount of the diffusing agent. Further, the light-shielding convex portion 5 side may be released from the mold at a releasing point 17 of the second roll 14 so that the temperature is not higher than the thermal deformation temperature of the resin. Is performed uniformly, and the light-shielding layer can be formed smoothly, and unevenness does not occur, which is preferable.

The present invention will be described in more detail with reference to specific examples. Example 1 First, a Fresnel lens sheet was formed by press molding a cast acrylic plate having a refractive index of 1.49. Next, a molding acrylic resin having a hardness of 80, an acrylic rubber added to the extrusion acrylic resin and a hardness of 80, a refractive index of 1.52, and a heat distortion temperature of 100 ° C. was used as a raw material resin, and was refracted with respect to 100 parts by weight of the resin. A cross-linked acrylic resin bead having a rate of 1.49 was added in an amount of 15 parts by weight to prepare the first unit of the apparatus shown in FIG.
The roll is provided with a lenticular lens mold, the second roll is provided with a light-shielding layer printing convex mold, and the lenticular lens surface is 140 ° C. when released from the mold of the first roll.
Also, the convex portion for printing the light-shielding layer released from the second roll has a temperature of 95 ° C.
A sheet was prepared by an extrusion molding method while controlling the mold temperature so that the above, and the light-shielding printing was performed on the convex portion for printing the light-shielding layer of the sheet by the roll coating method to obtain a lenticular lens sheet. The above hardness is Rockwell hardness (ASTM
D785). After setting the above Fresnel lens sheet and lenticular lens sheet so that the Fresnel lens surface and the lenticular lens surface are aligned to form a transmissive screen and carrying out a transportation test, the screen was checked, and light shielding printing by printing was performed. No unevenness or scratches due to rubbing of the Fresnel surface of the Fresnel lens sheet, and the angle of view and image quality were excellent.

[0016]

As described above, the transmissive screen of the present invention has the following effects by adopting the above configuration. The present invention uses the resin of the crosslinked resin beads used as the diffusing agent, which is obtained by crosslinking the same resin as the resin forming the lenticular lens or a resin obtained by modifying the resin, and the surface hardness of the lenticular lens sheet is Fresnel lens sheet. By using a smaller one than the surface hardness of, even if the Fresnel lens surface set facing the lenticular lens surface contacts and rubs, the Fresnel lens surface is not scraped and the image quality does not deteriorate, A transmissive screen having sufficient diffusivity can be obtained.

The difference in refractive index between the organic resin beads and the lenticular lens sheet resin is 0.005 to 0.0.
When the range is 5, the amount of the diffusing agent added can be appropriately suppressed, and it is not necessary to use an expensive diffusing agent more than necessary. Further, the amount of the diffusing agent is suppressed to an appropriate amount and the surface unevenness becomes tight. In addition, the reflectance does not become too high and the screen contrast does not decrease. Further, if the difference in refractive index is the above, even if a large amount of a diffusing agent is added to the resin for the lenticular lens sheet to increase the diffusion,
Since the reflectance of the screen and the size of the diffusion due to the reflection at the interface with the resin are balanced, it is possible to cover the reduction in the diffusion due to the mold return when molding the lenticular lens.

When molding a lenticular lens surface, the mold is released from the lenticular lens mold at a temperature higher than the heat deformation temperature to cause the resin for the lenticular lens to return to the mold, and the organic material protruding to the surface of the lenticular lens. By forming the concave portion caused by the resin beads to be smaller than the curvature of the organic resin beads, it is possible to minimize the convex portion due to the resin beads on the surface of the lenticular lens and prevent the Fresnel lens from being scraped more reliably.
Further, in that case, it becomes possible to use a resin having a large mold reversion such as an acrylic resin to which rubber is added, and as a result, the fragility, which is a drawback of the acrylic resin, is improved, and it can be applied to a product with a thin plate thickness. It is possible.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an example of a transmission screen of the present invention.

FIG. 2 is a schematic diagram for explaining a method of manufacturing a lenticular lens sheet.

[Explanation of symbols]

 1 Transmissive screen 2 Fresnel lens sheet 3 Lenticular lens sheet 4 Fresnel lens surface 6 Lenticular lens surface 11 Lenticular lens mold

Claims (3)

[Claims] 1. A transmission screen comprising a Fresnel lens surface of a Fresnel lens sheet and a lenticular lens surface of a lenticular lens sheet facing each other, wherein the lenticular lens sheet has a surface hardness smaller than that of the Fresnel lens sheet. A transmissive screen, wherein the lenticular lens sheet is kneaded with a resin for the lenticular lens sheet or a resin obtained by modifying the resin for the lenticular lens sheet as a light diffusing agent, the organic resin beads being crosslinked. 2. The transmissive screen according to claim 1, wherein the difference in refractive index between the organic resin beads and the resin for the lenticular lens sheet is in the range of 0.005 to 0.05. 3. A lenticular lens sheet is manufactured by extrusion molding of an acrylic resin containing rubber, and at least the surface of the lenticular lens is released from the lenticular lens mold at a temperature not lower than the heat deformation temperature of the resin for the lenticular lens. The transmissive screen according to claim 1 or 2, wherein the convex portion due to the organic resin beads protruding on the surface of the lenticular lens is formed to be smaller than the organic resin beads.