JPH0453944A - Transmission type screen - Google Patents

Abstract

PURPOSE:To improve the horizontal and vertical directivity of a projected image and image quality by making the relation between the light diffusivity of a lenticular sheet and 1st and 2nd lenticular lenses specified one. CONSTITUTION:The light diffusivity in which haze value H of a material is 60-90% is added to the lenticular sheet 3. The 1st lenticular lens 3a in a lateral direction is formed on the incident surface of the sheet 3 and the 2nd lenticular lens 3b in a longitudinal direction, which is orthogonally crossed with the lens 3b, is formed on the exiting surface of the sheet 3. Then, the ratio D/L1 of the pitch L1 of the 1st lenticular lens 3a to the depth D of the lens 3a satisfies the condition of an inequality I and the ratio of the L1 to the pitch L2 of the 2nd lenticular lens 3b satisfies the condition of an inequality II. The ratio of the pitch of the lens is selected according to the haze value of the sheet material. Thus, the excellent image quality in which the occurrence of moire is restrained is obtained and a light beam transmissivity is enhanced, then the directivity in the horizontal and vertical directions is made large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmissive screen used in a projection television, a transmissive projection enlarging device, and the like. More specifically, the present invention relates to a transmissive screen with improved horizontal and vertical directivity and image quality of projected images.

[Conventional technology and issues to be solved]

Conventionally, transmissive screens used in projection televisions and the like have used a combination of a Fresnel sheet with a circular Fresnel lens shape and a lenticular sheet with a lenticular lens that diffuses transmitted light in the horizontal direction. Figure 5 shows an example. The lenticular sheet usually contains a diffusing agent, and this diffusing agent prevents the occurrence of hot hands where the light source can be seen through, and also achieves vertical light diffusion. However, if the content of this diffusing agent is low, although the light transmittance is good, there is a problem that the moiré pattern, which is caused by interference between the pitches of the lenticular lens and Fresnel lens, can be seen on the viewing side through the lenticular sheet. . Further, it is not possible to obtain a large diffusivity in the vertical direction. On the other hand, if the amount of the diffusing agent added is large, the vertical diffusivity increases, but there is a problem that the light transmittance of the screen decreases, the screen becomes dark, the image becomes blurred, and the resolution decreases.

Therefore, the content of the diffusing agent is limited, and as a result, there is a problem that the viewing angle in the vertical direction cannot be increased without reducing the light transmittance. In order to solve this problem, a method has been devised in which a transmissive screen consisting of a Fresnel sheet and a lenticular sheet is formed with horizontal lenticular lenses on the surface of the Fresnel sheet opposite to the surface on which the circular lenses are formed. There is. An example of this is shown in FIG. However, in this invention, when the horizontal lenticular lens is directed toward the light source, the amount of invalid light on the Fresnel lens surface increases due to refraction of the optical path in the vertical direction within the Fresnel sheet. The problem remains that sufficient vertical diffusion cannot be achieved. Further, when the Fresnel lens surface is directed toward the light source side, there is a problem that the amount of invalid light increases in the peripheral area and the peripheral area becomes dark.

[Means to solve the problem]

The present inventors have proposed that in a transmission screen made of a Fresnel sheet and a lenticular sheet, a lenticular lens is provided on the light source side of the lenticular sheet to diffuse the transmitted light in the vertical direction (that is, in the lateral direction), and on the exit surface. A second lenticular lens is provided (on the viewing side) that diffuses light in a direction perpendicular to this (horizontal direction) (that is, in the vertical direction), and a specific relationship is established between the two and the lenticular sheet material with light diffusing properties. It was discovered that a transmission type screen exhibiting excellent performance could be obtained in some cases, and the present invention was completed.

That is, the present invention provides a transmission screen comprising a Fresnel sheet and a lenticular sheet disposed on the exit surface side of the Fresnel sheet, in which the lenticular sheet has a material having a haze value (H) of 60% to 90%. Transmissive type, which has light diffusivity and has a first horizontal lenticular lens formed on its entrance surface, and a second vertical lenticular lens perpendicular to this formed on its exit surface. The screen is such that the ratio (D/L 1) between the pinch (L1) of the first lenticular lens and the depth (D) of the lenticular lens satisfies the following condition (a), and Ll This is a transmission screen characterized in that the ratio of the pitch (L2) of the second lenticular lens and the pitch (L2) of the second lenticular lens satisfies the following condition (b).

Here (a) 0.05≦D/L 1≦0.20(
b) When 60%≦H〈75%, 0.20≦L 1 / L 2 <O,,5075%≦
When H≦90%, 0.50≦Ll/L2≦1.0 The present invention will be described below with reference to FIG. 1.2.3.4.

Figure 1.2 shows one embodiment of the invention.

(1) indicates a Fresnel sheet, and (3) indicates a lenticular sheet.

As these base materials, acrylic resins or acrylic resins are particularly excellent in terms of optical properties and moldability, but polycarbonate, vinyl chloride,
Styrenic resins can also be used.

The material of the lenticular sheet used in the present invention is given light diffusivity with a haze value of 60% to 90%. Here, the lenticular lens material refers to a lenticular lens sheet imparted with diffusivity when no lenticular lens is formed, that is, when the lens surface is flat.

Methods for imparting diffusivity include, but are not particularly limited to, methods such as incorporating a diffusing agent into the lenticular sheet, making the surface of the lenticular sheet matte, or pasting a diffusive film on the lenticular sheet. Both methods can be used.

Among these, in the method using a diffusing agent, glass beads, CaCO3, BaSO4, Ti0zAl are used as the diffusing agent.
One or more types of fine particles such as inorganic fine particles such as z03 or organic crosslinked polymer fine particles can be used.

It is also effective to add dyes and pigments such as carbon black to the lenticular sheet in order to adjust the color tone of the screen.

The diffusivity imparted to the lenticular sheet provides vertical diffusivity as a screen. This vertical diffusivity is correlated with the haze value, which indicates the diffusivity of the wrench material. As the haze value increases, the vertical diffusivity improves. However, when the haze value exceeds 90%, the light transmittance decreases significantly, resulting in a decrease in screen gain. Also, the haze value is 60
If it is smaller than %, the screen gain will be higher, but
A hot hand occurs. Therefore, the haze value of the screen material is preferably between 60% and 90%.

The present invention has been made in order to maintain high vertical diffusivity of a screen without reducing light transmittance, and to obtain a good projected image.

In the transmission screen of the present invention, the lenticular sheet is provided with a first lenticular lens 3a on the light source side for diffusing light in the vertical direction, and a first lenticular lens 3a on the observation side for diffusing light in the horizontal direction. A two-lenticular lens 3b is formed. The profile of the first lenticular lens on the light source side is not limited as long as it has the function of diffusing light in the vertical direction. For example, a substantially arcuate shape is preferable, and among these, a semicircular or semielliptical shape is particularly preferable because of its simple shape. The profile of the second lenticular lens on the observation side is not limited as long as it has the function of diffusing light in the horizontal direction. For example, a substantially arcuate shape is preferred, and a semicircular or semielliptical shape is especially preferred. Furthermore, it is most preferable to use one having a semicircular or semielliptical profile, a total reflection surface 3d and a total reflection light output surface 3e, and improved horizontal directionality. This is shown in Figure 3.4. Furthermore, if necessary, an external light absorbing layer 3c can be provided in the light-opaque portion of the lens to improve the contrast of the image.

The larger the ratio (D/L1) of the pitch (L1) of the first lenticular lens to the depth (D) of the lenticular lens, the better the vertical diffusivity, but since the transmitted light is dispersed in the vertical direction, the center gain decreases. Also, (D/L
If L) is too small, the effect of improving vertical diffusivity will be reduced. Therefore, from this point of view (D/L 1 )
The range is 0.05≦D/L1≦0.20, preferably 0.10≦D/L1≦0.15.

In the present invention, since the first lenticular lens imparts vertical diffusivity, it is possible to improve the vertical diffusivity while keeping the light transmittance high, compared to the case where the diffusion effect is provided by a diffusing agent.

If the haze value of the lenticular lens sheet is small, moiré will occur due to interference between the Fresnel lens and the lenticular lens due to their pitch ratio.

The pitch of the Fresnel lens is generally 0.1 to 0.5 degrees, but preferably 0.1 to 0.2 degrees to obtain a good projected image. On the other hand, the pitch of lenticular lenses is generally 1.0 mm or less, and lenticular lenses of about 0.1 ann can be manufactured, but if the pitch is greater than 0.8 mm, moiré tends to occur.

When the lenticular sheet material has a relatively high diffusivity and the haze value is between 75% and 90%, no moiré pattern is observed. If the haze value is less than 75%, a radial moire pattern is created by interference between the lattice pattern formed by the first lenticular lens and the second lenticular lens and the circular pattern of the Fresnel lens. However, the light passes through the diffusion layer and becomes visible from the viewing side, reducing image quality. Therefore, the present inventors conducted intensive studies to eliminate the moire pattern by changing the ratio (L1/L2) of the pitch L1 of the first lenticular lens to the pitch L2 of the second lenticular lens, and as a result, ( Ll/L
2) It was found that no moiré pattern was observed below a certain value. However, on the other hand, if Ll is too small, it takes time to process the mold, which is not economical. Therefore, (
The range of Ll/L2) is 0.20≦L 1 /L 2 <0.50 when 60%≦H<75%, preferably 0.25≦L1/L2≦0.35, and 75%≦H≦90%. When 0.50≦Ll/L2≦1.00, preferably 0.80≦Ll/L2≦1.00.

〔Example〕

The present invention will be explained below with reference to examples, but these are not intended to limit the invention.

Example 1 (Screen material) Average particle size 30, consisting of 40 parts by weight of methyl methacrylate, 30 parts by weight of butyl acrylate, and 30 parts by weight of styrene.
5% of organic crosslinked polymer particles of μ were added to Delpet 70H (acrylic resin manufactured by Asahi Kasei Kogyo ■) and extrusion molded to obtain a 2 mm thick diffusion plate. The haze value of the diffuser plate measured with a haze meter (Model 1001DP) manufactured by Nippon Heavy Industries was 86%.

(Lens molding) A first lenticular lens mold having a semi-cylindrical lens shape with L 1 =0.5 am and D/L 1 =0.15, and a total reflection part with L 2 =0.5 mn. A screen material was sandwiched between the mold and a second lenticular lens mold having a lens shape including a semi-cylindrical portion, and a lenticular lens sheet was obtained by press molding.

A Fresnel sheet made of transparent acrylic resin was obtained using a Fresnel lens mold with a pitch of 0.14 mm and a mirror plate.

(Evaluation) The obtained transmission screen was attached to a 40-inch projection television, and the screen gain and brightness distribution were measured. In addition, we observed moire patterns on the screen surface and the presence or absence of hot hands, but neither moire nor hot bands were observed.

The vertical diffusivity of the screen was expressed as a viewing angle (βV) indicating a brightness of 173, which is the center brightness, and was βV=25″.

Examples 2 to 4 and Comparative Examples 1 to 3 The haze value, D/L 1 and Ll/L2 of the materials were changed. Fresnel lens mold similar to Example 1, L 2 =
Screens were molded using the second lenticular lens mold of 0.50 mm and the first lenticular lens mold with different lengths and LL, and their performance was investigated.

The results are shown in Table 1.

Table 1 [Effects of the Invention] According to the screen of the present invention, a lenticular lens that diffuses light in the vertical direction is formed on the light source side of the lenticular sheet, and a lenticular lens that diffuses light in the horizontal direction is formed on the observation side. At the same time, the lens pitch ratio is selected according to the haze value of the sheet material, so it is possible to obtain good image quality with less moiré, as well as high light transmittance and directivity in the horizontal and vertical directions. You can make it bigger.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a transmission screen of the present invention. Figure 2.3.4 is a sectional view of the transmission screen of the present invention. FIG. 5 is a perspective view of a conventional transmission screen. FIG. 6 is a perspective view of a conventional transmission screen with lateral lenticular lenses. 1- Fresnel lens sheet, Ia- (lateral) lenticular lens that diffuses light in the vertical W direction, 1b-
Fresnel lens, 2 - conventional lenticular lens sheet, 3 - lenticular lens sheet of the present invention, 3 a - lenticular lens that diffuses light in the vertical direction (lateral direction), 3 b - lenticular lens that diffuses light in the horizontal direction (vertical direction); of)
Lenticular lens, 30m external light absorption layer, 3D total reflection surface, 3E total reflection light output surface Patent applicant Asahi Kasei Corporation

Claims (1)

[Claims] 1. In a transmission screen comprising a Fresnel sheet and a lenticular sheet disposed on the exit surface side of the Fresnel sheet, the lenticular sheet has a haze value (H) of 60% to 90%. A first lenticular lens made of a light-diffusing sheet material is formed on the incident surface to diffuse light in a direction perpendicular to the first lenticular lens, and a second lenticular lens is formed on the exit surface to diffuse light in a direction perpendicular to the first lenticular lens. The transmission screen has a ratio (D/L1) of the pitch (L1) of the first lenticular lens and the depth (D) of the lenticular lens,
The following condition (a) is satisfied, and the ratio of L1 to the pitch (L2) of the second lenticular lens is as follows (b)
A transparent screen that satisfies the following conditions. Here, (a) 0.05≦D/L1≦0.20 (b) 0.20≦L1/L2<0.50 when 60%≦H<75% 0 when 75%≦H≦90% .50≦L1/L2≦1.0