JP2007286326A - Lenticular lens sheet for transmissive screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lenticular lens sheet for a transmissive screen, the sheet capable of controlling distribution of viewing angles in horizontal and vertical directions and having little unevenness in the distribution of viewing angles. <P>SOLUTION: The lenticular lens sheet used for a transmissive screen includes a transparent resin layer 22 having a first refractive index formed on a base 23, and a second transparent resin layer 21 having a refractive index larger than the first refractive index and formed on the first transparent resin layer 22, and has a diffusion layer having ellipsoidal convex protrusions or concave recesses to obtain a light diffusion effect on an exit surface of the base of the lenticular lens sheet 220. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lenticular lens sheet for a transmission screen.

  According to the present invention, the effect of the lenticular lens sheet is to obtain a favorable viewing angle characteristic with a wide range and little unevenness due to a difference in gain, and with a balance between the horizontal direction and the vertical direction.

  The present invention relates to a lenticular lens sheet for a transmission screen, and can be suitably used particularly for a screen of a rear projection television.

  A transmissive screen used in a rear projection television includes a Fresnel lens sheet that adjusts in parallel the image light projected from the optical engine inside the rear projection television housing, and parallel light emitted by the Fresnel lens sheet. It is composed of a lenticular sheet having an effect of widening the viewing angle by diffusing toward the viewer side.

  In the conventional lenticular lens sheet, the incident surface of the lenticular lens sheet has a cylindrical shape with a width of several tens to several hundreds of μm in order to have a wide viewing angle distribution mainly in the horizontal direction, and the horizontal screen dimension width. There is a stripe structure type in which a plurality of them are arranged together. In general, light is condensed on the exit surface of the lenticular lens sheet by the effect of the cylindrical shape, and a light absorbing portion (black stripe) is provided in an area other than the condensing portion for the purpose of improving the contrast of the image. .

In addition, there is a screen structure different from the above, and a screen structure in which light is diffused using total reflection by a substantially trapezoidal inclined portion having a low refractive index. A diffusion sheet mixed with diffusing particles is disposed on the exit surface side of the screen, and a prism sheet is further provided at the screen incident portion, thereby providing a wide viewing angle distribution in the horizontal direction. (For example, refer to Patent Document 1.)
Japanese Patent Application Laid-Open No. 2004-110002 (page 10, FIG. 2)

  However, in the conventional stripe-type lenticular lens sheet in which cylindrical lenses are arranged in the horizontal direction of the screen, the horizontal viewing angle distribution depends on the internal structure of the lenticular lens sheet, and the curvature and refraction of the lenticular lens By changing the rate, some degree of control is possible, but the vertical viewing angle distribution has no control factor due to the internal structure of the lenticular lens sheet, mainly the effect of the diffuser plate on the lenticular lens sheet exit surface side Therefore, there is a problem that it is difficult to obtain a wider viewing angle distribution in the vertical direction that satisfies the screen performance requirement.

  Further, in the configuration of Patent Document 1, in the conventional method, the light is totally reflected by the substantially trapezoidal inclined portion having a low refractive index, and is emitted at a specific angle due to the difference in the refractive index of the screen exit surface. The light is emitted from the screen in the direction perpendicular to the screen without reflection. When the exit side of the screen is observed with this structure, the vertical direction of the screen and a specific angular direction (substantially trapezoidal slope with a low refractive index) If the angle formed between the horizontal direction of the screen and the screen is 80 [deg], light is observed brightly only in three directions (± 20 to 25 [deg] from the vertical direction of the screen). As a means for providing a wide viewing angle distribution, a prism sheet 31 that diffuses by refracting incident light as shown in FIG. 12 is provided, but when the apex of each prism of the prism sheet 31 is increased, The tolerance of the total reflection angle determined by the ratio of the refractive index of the transparent resin (high refractive index layer) 33 and the transparent resin (low refractive index layer) 34 is exceeded, and light passes through the transparent resin (low refractive index layer) 34. Since the light is transmitted, a large deflection angle cannot be obtained. Therefore, as shown in FIG. 13, a valley is seen in the curve near the viewing angle of 0 [deg] and ± 15 to 20 [deg], and a favorable viewing angle characteristic is obtained. There was a problem that it could not be obtained.

  The present invention solves the above-mentioned conventional problems, facilitates control of the viewing angle distribution in each of the horizontal direction and the vertical direction, and obtains a wide viewing angle characteristic over a wide range, and is a lenticular lens for a transmission type screen. The purpose is to provide a sheet.

In order to solve the above-described conventional problems, a lenticular lens sheet for a transmissive screen according to the present invention includes a transparent resin layer having a first refractive index formed on a substrate in the lenticular lens sheet used for the transmissive screen. A second transparent resin layer having a refractive index greater than the first refractive index formed on the first transparent resin layer,
In order to obtain a light diffusing effect on the emission surface of the base material of the lenticular lens sheet, a substantially oval spherical convex protrusion or a concave concave diffusion layer is provided.

  According to the lenticular lens sheet for a transmission type screen of the present invention, the viewing angle distribution in each of the horizontal direction and the vertical direction is controlled by adjusting the aspect ratio of the shape seen from the observer in the convex or concave projection. It is possible. Further, the degree of diffusion or the transmittance of the screen can be controlled by adjusting the size of the internal curvature of the convex or concave protrusion. In addition, in the distribution of viewing angle characteristics, by providing optimal convex or concave projections on the exit surface of the diffusion sheet, it is possible to obtain good viewing angle characteristics over a wide range with less unevenness due to differences in the viewing position of the screen. be able to.

  Hereinafter, embodiments of the lenticular lens sheet for a transmission screen according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a horizontal sectional view of a transmissive screen in Example 1 of the present invention, and FIG. 2 shows a horizontal sectional view of a lenticular lens sheet for a transmissive screen in Example 1 of the present invention. FIG. 3 is a perspective view of the lenticular lens sheet, and FIG. 4 is a front view of the lenticular lens lens sheet as viewed from the observer side.

  In FIG. 1, the transmission screen 100 includes a base material 13, a first transparent resin layer (low refractive index layer) 12, a second transparent resin layer (high refractive index layer) 11, and a Fresnel lens sheet 110. The Fresnel lens sheet 110 is formed in concentric circles, and the pitch between the concentric circles is about 100 μm.

  The dimension of the first transparent resin layer (low refractive index layer) 12 having a triangular cross section is such that the length between the adjacent bases is 25 μm, and the two transparent resin layers (low refractive index layers) 12 are The length connecting each vertex is 64 μm, and the length from the top to the bottom of the transparent resin layer (low refractive index layer) 12 is 148 μm. Further, for the purpose of improving the contrast of an image, a black light shielding layer may be provided on the surface which is the bottom of the first transparent resin layer (low refractive index layer) 12.

  In the transmissive screen 100, the projected image light is transmitted through the Fresnel lens sheet 110 to be parallel light, and the light is incident on the lenticular lens sheet 120. The second transparent resin layer (high refractive index layer) 11 having a refractive index facing the incident side of about 1.56 is transmitted, and the refractive index lower than that of the transparent resin layer (high refractive index layer) 11 is about 1.46. The surface of a certain first transparent resin layer (low refractive index layer) 12 is reflected and passes through an opening that is a boundary portion between the transparent resin layer (low refractive index layer) 12 and the base material 13. The material of the substrate 13 is a PET film, and the refractive index is approximately 1.57.

  The size of the concave shape 14 formed on the emission side of the base material 13 is an elliptical sphere shape having a horizontal direction of 40 μm and a vertical direction of 80 μm as viewed from the observer side, and a pitch ratio (ellipse) between the horizontal direction and the vertical direction. The ratio of the minor axis to the major axis of the shape is preferably about 1: 2. The concave shape 14 formed on the emission side of the substrate 13 can have a wide diffusion effect in the horizontal direction by making the pitch length in the vertical direction longer than the horizontal direction. Therefore, by adjusting the pitch ratio between the horizontal direction and the vertical direction, it is possible to control the ratio of the light quantity distribution of the two-direction components. The minimum curvature radius of the concave shape in the horizontal direction is preferably about 20 μm. The size of the minimum radius of curvature can be set arbitrarily, and the smaller the value, the more the diffusion effect can be expected. However, when light is emitted to the outside of the screen, it is totally reflected at the concave boundary surface and causes a decrease in transmittance. . Instead of the concave shape, a convex shape symmetrical about the plane of the substrate 13 may be formed.

  As a means for forming the concave shape 14 on the emission side of the base material 13, it is created by an extrusion forming method using a mold in which convex elliptic sphere shapes are arranged.

  The same effect can be obtained by providing an elliptical spherical convex protrusion in addition to the concave on the exit surface of the lenticular lens sheet 120.

  Assuming that the substantially elliptical convex protrusions or concave depressions formed on the exit surface of the lenticular lens sheet 120 have a horizontal pitch length X μm and a vertical pitch length Y μm, 5 μm ≦ X ≦ 500 μm It is set within the range of 5 μm ≦ Y ≦ 500 μm.

  When the pitch length is smaller than 5 μm or larger than 500 μm, the diffusion effect due to the effect of the concave shape 14 provided on the exit surface side of the base material 13 cannot be obtained, and the viewing angle distribution curve is remarkable. This is because valleys are seen and the viewing angle distribution is not optimal as a transmission screen.

  As described above, in the present embodiment, by providing the diffusion layer having the concave portion 14 having a substantially elliptical spherical shape on the emission surface of the base material 13, the light is refracted by the curvature effect of the concave surface and has a diffusion effect. Thus, viewing angle characteristics as shown in FIG. 5 are obtained.

  FIG. 6 shows a horizontal sectional view of a transmissive screen in Example 2 of the present invention, and FIG. 7 shows a horizontal sectional view of a lenticular lens sheet for a transmissive screen in Example 2 of the present invention. FIG. 8 is a perspective view of the lenticular lens sheet.

  In FIG. 6, a transmissive screen 200 includes a Fresnel lens 210, a transparent resin layer (high refractive index layer) 21, a transparent resin layer (low refractive index layer) 22, a base material 23, an adhesive layer 24, a diffusion sheet 25, a concave shape. The lenticular lens sheet 220 is composed of 27. The diffusion sheet 25 includes spherical diffusion particles 26 having a radius of about 5 μm to 10 μm. The diffusing particle diameter is a size used for a general lenticular lens sheet for a transmission type screen.

  The diffusion particles 26 are made of any resin material such as acrylic, polyurethane, or styrene.

  The Fresnel lens sheet 210 has a pitch length of 100 μm and is concentric from the center of the Fresnel lens sheet.

  Further, the length between the bases of two adjacent transparent resin layers (low refractive index layers) 22 is 25 μm, and the length connecting the vertices of the two transparent resin layers (low refractive index layers) 22 is 64 μm. The length from the top to the bottom of the transparent resin layer (low refractive index layer) 22 is 148 μm. Further, for the purpose of improving the contrast of an image, a black light shielding layer may be provided on the surface which is the bottom side of the transparent resin layer (low refractive index layer) 22.

  The dimension of the first transparent resin layer (low refractive index layer) 22 having a triangular cross section is the same as that of Example 1, and the difference from Example 1 is that a diffusion sheet 25 containing diffusion particles 26 is provided. It is.

  The transmissive screen 200 converts the projected image light through the Fresnel lens sheet 210 into parallel light, and the light beam enters the lenticular lens sheet 220. A transparent resin that passes through the transparent resin layer (high refractive index layer) 21 having a refractive index n1≈1.56 facing the incident side and has a refractive index n2≈1.46 lower than that of the transparent resin layer (high refractive index layer) 21. The surface of the layer (low refractive index layer) 22 is reflected and passes through an opening that is a boundary portion between the transparent resin layer (low refractive index layer) 22 and the base material 23. The material of the base material 23 is a PET film, and the refractive index is 1.57.

  As for the addition of the diffusion sheet 25 different from the configuration of the first embodiment, the adhesive layer 24 is applied to the emission surface side of the base material 23, and the diffusion sheet 25 having a thickness of about 1 mm is adhered in a sandwiched manner.

  The refractive index of the adhesive layer 24 is approximately 1.51, and the material is acrylic. The refractive indexes of the base material of the diffusion sheet 25 and the internal particles 26 scattered inside are approximately 1.55 and approximately 1.59, respectively. The volume ratio of the internal particles to the base material of the diffusion sheet is about 9%.

  The size of the concave shape 27 formed on the exit side of the diffusion sheet 25 is an oval shape with the horizontal direction of 40 μm and the vertical direction of 80 μm as viewed from the observer side, and the pitch ratio between the horizontal direction and the vertical direction is 1 : About 2 is desirable. The concave shape 27 formed on the emission side of the diffusion sheet 25 can have a wide diffusion effect in the horizontal direction by making the pitch length in the vertical direction longer than in the horizontal direction. Therefore, by adjusting the pitch ratio between the horizontal direction and the vertical direction, it is possible to control the ratio of the light quantity distribution of the two-direction components. The minimum curvature radius of the concave shape in the horizontal direction is 20 μm. The size of the minimum radius of curvature can be set arbitrarily, and the smaller the value, the more the diffusion effect can be expected. However, when light is emitted to the outside of the screen, it is totally reflected at the concave boundary surface and causes a decrease in transmittance. . Moreover, you may make it a convex shape symmetrical with respect to the plane of the diffusion sheet 25 instead of the concave shape.

  When the diffusion sheet 25 having a thickness of about 1 mm is installed on the exit surface side of the lenticular lens sheet 220, a substantially elliptical convex protrusion or a concave recess formed on the exit surface is disposed in the horizontal direction. Assuming that the pitch length is X μm and the pitch length in the vertical direction is Y μm, it is desirable that the pitch length is set in the range of 5 μm ≦ X ≦ 500 μm and 5 μm ≦ Y ≦ 500 μm. When each pitch length is smaller than 5 μm, a significant valley is seen in the viewing angle distribution curve as shown in FIG. 10, and when larger than 500 μm, the gain at the central portion of the viewing angle distribution becomes higher as shown in FIG. Therefore, a sufficient diffusion effect cannot be obtained in both cases, and the viewing angle distribution optimal for a transmission type screen cannot be obtained.

  As a means for forming the concave shape 27 on the emission side of the diffusion sheet 25, it is created by an extrusion forming method using a mold in which convex elliptical shapes are arranged.

  As described above, in the present embodiment, by providing the concave shape 27 on the emission surface of the diffusion sheet 25, the light is refracted by the curvature effect of the concave surface, and a diffusion effect can be obtained.

  In this embodiment, the diffusion layer provided on the emission surface side of the lenticular lens sheet portion is formed of a diffusion material filled with diffusion particles, so that the diffusion effect is further spread and a good viewing angle characteristic is obtained. Obtainable.

  As a result, the viewing angle characteristic as shown in FIG. 9 is obtained, and the half-value angle α of the peak gain is 25 degrees in the horizontal direction and 15 degrees in the vertical direction.

Sectional drawing of the transmission type screen using the lenticular lens sheet in Example 1 of this invention Sectional drawing of the lenticular lens sheet | seat for transmissive screens in Example 1 of this invention The perspective view of the lenticular lens sheet for transmissive screens in Example 1 of the present invention The front view of the lenticular lens sheet for transmissive screens in Example 1 of the present invention The figure which shows the viewing angle characteristic of the emitted light by the lenticular lens sheet for transmissive screens shown in FIG. Sectional drawing of the transmissive screen using the lenticular lens sheet in Example 2 of this invention Sectional drawing of the lenticular lens sheet | seat for transmission type screens in Example 2 of this invention The perspective view of the lenticular lens sheet | seat for transmissive screens in Example 2 of this invention The figure which shows the viewing angle characteristic of the emitted light by the lenticular lens sheet for transmissive screens shown in FIG. The figure which shows the viewing angle characteristic of the emitted light when the pitch of the unevenness | corrugation of an output surface is 5 micrometers in a horizontal and vertical direction in the lenticular lens sheet for transmissive screens shown in FIG. The figure which shows the viewing angle characteristic of the emitted light in case the pitch of the unevenness | corrugation of an output surface is 500 micrometers in a horizontal and vertical direction in the lenticular lens sheet for transmissive screens shown in FIG. Sectional view of a conventional lenticular lens sheet for transmissive screens The figure which shows the viewing angle characteristic of the emitted light by the conventional lenticular lens sheet | seat for transmissive screens shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Transmission type screen 110 Fresnel lens sheet 120 Lenticular lens sheet 11 Transparent resin (high refractive index layer)
12 Transparent resin (low refractive index layer)
13 Substrate 14 Concave shape 200 Transmission type screen 210 Fresnel lens sheet 220 Lenticular lens sheet 21 Transparent resin (high refractive index layer)
22 Transparent resin (low refractive index layer)
DESCRIPTION OF SYMBOLS 23 Base material 24 Adhesion layer 25 Diffusion sheet 26 Diffusion particle 27 Concave shape 320 Lenticular lens sheet 31 Prism lens sheet 32 Base material 33 Transparent resin (high refractive index layer)
34 Transparent resin (low refractive index layer)
35 Diffusion sheet 36 Diffusion particles

Claims (7)

In the lenticular lens sheet used for the transmission screen,
A transparent resin layer having a first refractive index formed on the substrate;
A second transparent resin layer having a refractive index greater than the first refractive index formed on the first transparent resin layer,
A lenticular lens sheet for a transmission type screen, characterized by having a substantially elliptic spherical convex protrusion or a concave concave diffusion layer in order to obtain a light diffusing effect on the exit surface of the base material of the lenticular lens sheet. 2. The convex protrusion or the concave recess has the same pitch ratio in the horizontal direction and the vertical direction, or the pitch length in the vertical direction is larger than the pitch length in the horizontal direction. Lenticular lens sheet for transmissive screens. 3. The convex protrusion or the concave dent is 5 μm ≦ X ≦ 500 μm, 5 μm ≦ Y ≦ 500 μm, where the horizontal pitch length is X μm and the vertical pitch length is Y μm. The lenticular lens sheet for transmissive screens described in 1. The lenticular lens sheet for a transmission type screen according to claim 2, wherein the diffusion layer is filled with diffusion particles smaller than the elliptical shape. The lenticular lens sheet for a transmissive screen according to claim 4, wherein the diffusion particles are made of a resin material of acrylic, polyurethane, or styrene. The lenticular lens sheet for a transmissive screen according to claim 5, wherein the first refractive index is approximately 1.46, and the second refractive index is approximately 1.56. A transmissive screen using the lenticular lens sheet according to claim 1.

Images