JP4474972B2 - Light diffusing lenticular lens sheet - Google Patents

Description

  The present invention relates to a light diffusive lenticular lens sheet constituting a rear projection screen, and more particularly to a light diffusive lenticular lens sheet comprising a sheet having a bonded structure in which a lens array portion and a base material portion are bonded together.

  Conventionally, rear projection screens (also known as transmissive rear screens) have been widely used as projection screens for enlarging and projecting optical images and display screen screens.

  In general, a rear projection screen has a Fresnel lens sheet made of synthetic resin for converting the projection light of the optical image into parallel light on the back side (optical image projection side) of the screen that projects the optical image from the projection projector. A light diffusing sheet made of a synthetic resin lenticular lens sheet imparted with light diffusibility is arranged on the screen front side of the image observation side. The light diffusive lenticular lens sheet includes a lens array portion and a base. There are a sheet having an integrally molded structure in which the material part is formed by integral molding, and a sheet having a bonded structure in which the lens array part and the substrate part are bonded together.

  As shown in the plan view of FIG. 2, the lenticular lens sheet A imparted with the light diffusibility has a fine stripe shape (strands) on one surface in contact with the Fresnel lens sheet surface, The cross-sectional shape is provided with a bowl-shaped lenticular lens array portion 1 having the same pitch P, and the other flat surface is provided with a light diffusing surface 3 formed by a fine uneven rough surface, and is opposed to the valley portion of the lens array portion 1. On the diffusing surface 3, black stripes 4 (light-absorbing black and dark light-shielding patterns) having a predetermined width are formed and are incident on the lens array unit 1 facing the apex of the crests of the lens array unit 1. On the light diffusing surface 3 corresponding to the light converging part S of parallel light, a light transmitting part 5 (lens opening part) having a predetermined width is formed.

  The black stripe 4 is provided to prevent a decrease in contrast of the projected image due to the incidence of environmental noise light (external light) on the screen observation surface and difficulty in observing the projected image observed on the screen surface. ing.

  As a method of patterning the black stripes 4 on the lenticular lens sheet A, there is a conventional method that utilizes the optical orientation characteristics of the lenticular lens sheet. For example, as shown in FIGS. A photodegradable photoresist solution (black positive photosensitive solution) colored with a black pigment is applied to the light diffusing surface 3 on the light converging portion side facing the peak surface of the lens array portion 1 of the lenticular lens sheet 10. Then, after drying and solidifying to form the black photosensitive resin layer 11, as shown in FIG. 3C, the parallel light L1 by ultraviolet light is irradiated from the lens array portion 1 side, and the lens stripe direction is directed to the light diffusion surface 3 side. The black photosensitive resin layer 11 on the light diffusing surface 3 is exposed to ultraviolet light that has converged to a predetermined convergence width, and the exposed portions 11a facing the mountain portions of the lens array portion 1 are photodecomposed (A). Cali soluble decomposition) and, as shown in FIG. 3 (d), by developing and removing the exposed portion 11a at Karukari developer, pattern exposure method of patterning a black stripe 4 is employed.

  FIG. 4 is a partially enlarged side sectional view of the lens array portion 1 corresponding to one stripe (line) of the lenticular lens sheet A. The lens array portion 1 on one surface, the base material portion 2, and the other surface The light diffusing surface 3, the black stripe 4 on the light diffusing surface 3, and the light transmitting portion 5 (lens opening) are provided.

  For example, as shown in FIG. 4, using the light orientation characteristic of the lenticular lens sheet A, the parallel light L1 (incident light) that has passed through a Fresnel lens sheet (not shown) on the optical image projection side to become parallel light. Is incident on each of the stripe lens portions of the lens array portion 1 of the lenticular lens sheet A, and converged light L2 is formed while passing through the base material portion 2, and a predetermined light convergence width T (light Convergent exposure is performed on convergent light L2 having a width corresponding to the transmission portion 5.

  The black photosensitive resin layer exposed to the convergent light L2 converged on the light diffusing surface 3 is photodecomposed to change to a calcareous soluble state, and is developed and removed with an alkaline developer, whereby a lenticular lens sheet as shown in FIG. A light diffusing surface 3 includes black stripes 4 having a width (B = B1 + B2) and light transmitting portions 5 having a substantially light convergence width T along the stripe direction for each lens array portion 1 having a pitch P. Is formed.

  By the way, the lenticular lens sheet A imparted with the light diffusibility disposed on the observation side of the rear projection screen is an image of the observation image from the screen front (light diffusion surface) side by the projected image light incident from the lens array unit 1 side. In order to prevent a decrease in contrast due to environmental noise light (external light), blurring of an image, and difficulty in observation, it is desirable to reduce the light reflectance on the observation side surface of the screen as much as possible.

  For this purpose, the width (B1 + B2) of the black stripe 4 for each lens array 1 having the pitch P shown in FIG. 4 is increased as much as possible, and the width T of the light transmitting portion 5 (lens opening) for each lens array 1 can be obtained. It is required to increase the black stripe ratio Br shown below by narrowing as much as possible.

Here, as shown in FIG. 4, the black stripe ratio Br is obtained from the relationship between the pitch P for each lens array 1 and the width B (B = B1 + B2) of the black stripe 4 for each lens array 1.
Br = B / P = (B1 + B2) / P
Is required.

  In order to obtain such a high black stripe ratio Br, the width B of the black stripe 4 is increased as much as possible, and the width T of the light transmitting portion 5 (lens opening) of the lenticular lens sheet A is reduced as much as possible. It is necessary to set to.

  However, if the width T of the light transmitting portion 5 (lens opening) is too narrow, the outgoing light L3 (observation image light) is diffused by the light diffusing surface 3 and emitted from the light transmitting portion 5 with a predetermined observation viewing angle. However, the light is shielded by the end of the black stripe 4 forming the light transmitting portion 5, and there is a problem that sufficient orientation characteristics (such as the light gain of the screen outgoing light and the viewing viewing angle) cannot be obtained for the screen outgoing light L3. .

  Therefore, when increasing the black stripe ratio Br of the lenticular lens sheet A, it is important to control the light convergence width T of the ultraviolet light for exposure with respect to the light diffusion surface 3 in the pattern forming process of the black stripe 4.

Here, in FIG. 4, in order to converge the parallel light incident on the lens array portion 1 of the lenticular lens sheet A onto the light diffusion surface 3, the sheet thickness of the lenticular lens sheet A is set to t (the peak portion of the lens). The distance from the apex to the light diffusing surface), the lens pitch of the lens array unit 1 is P (stripe width), the lens curvature radius is R (O is the radius center), and the distance from the apex of the peak of the lens to the light convergence surface is f (focal length of lenticular lens)
f = t = [n / (n−1)] × R
And the parameters t, P, R, and f are set so that the convergence width T of the light converged on the light diffusion surface 3 is obtained based on the relational expression.

  In particular, when the light diffusing lenticular lens sheet is a sheet having a bonded structure in which the lens array portion 1 and the base material portion 2 are bonded together, it is used for the lens array portion 1 and the lens base material portion 2. There may be slight differences in the refractive index of the resin, and when different resins are used, there will be a clear difference in the refractive index of the resin used. Thus, even if pattern exposure is performed using a light diffusive lenticular lens sheet prepared by obtaining an appropriate light convergence width T by pattern formation of the black stripe B, it is difficult to obtain a sufficiently satisfactory black stripe ratio Br.

The known patent documents are described below.
Japanese Patent Application No. 7-210723 Japanese Patent Application No. 8-192340 Japanese Patent Application No. 8-237558 JP-A-10-231863

  An object of the present invention is to provide a light transmissive portion (lens opening portion) in a light diffusive lenticular lens sheet constituting a rear projection type screen comprising a laminated sheet obtained by laminating a lens array portion made of a synthetic resin and a base material portion. Is set to be as narrow as possible to obtain a high black stripe ratio Br, and is sufficient for screen emission light (observation image light) that is diffused on the light diffusion surface and emitted from the thin light transmission portion. The object is to obtain an optical gain, an observation viewing angle, and orientation characteristics.

  The invention according to claim 1 of the present invention comprises a bonded sheet comprising a lens array portion made of a synthetic resin, a substrate portion, a light diffusion surface, and a black stripe, and the lens array portion and the substrate portion are bonded together. In the light diffusing lenticular lens sheet constituting the rear projection screen, the relationship between the light refractive index n1 of the resin forming the lens array portion and the light refractive index n2 of the resin forming the substrate portion is | n1 −n2 | <0.03 or | n1−n2 | ≦ 0.03 is a light diffusing lenticular lens sheet.

  The invention according to claim 2 of the present invention comprises a laminated sheet comprising a lens array portion made of a synthetic resin, a substrate portion, a light diffusion surface, and a black stripe, and the lens array portion and the substrate portion are bonded together. In the light diffusing lenticular lens sheet constituting the rear projection screen, the relationship between the light refractive index n1 of the resin forming the lens array portion and the light refractive index n2 of the resin forming the substrate portion is 0 <| n1 − n2 | <0.03 or 0 <| n1−n2 | ≦ 0.03 is a light diffusing lenticular lens sheet.

  The invention according to claim 3 of the present invention is characterized in that, in the light diffusing lenticular lens sheet according to claim 1 or 2, the light refractive index n2 of the resin forming the base portion is 1.5. This is a light diffusing lenticular lens sheet.

  The light diffusing lenticular lens sheet of the present invention is a light diffusing lenticular lens sheet constituting a rear projection type screen, and includes a lens array portion 1 (lens peak side) and a lens base portion 2 made of synthetic resin. In a lenticular lens sheet having a light diffusing surface and a black stripe on the light converging side, the light refractive index n1 of the resin forming the lens array unit 1 (lens peak side) and the light converging side The relationship between the refractive index n2 of the resin forming the lens base portion 2 is expressed as | n1−n2 | <0.03, or | n1−n2 | ≦ 0.03, or 0 <| n1−n2 | By setting <0.03 or 0 <| n1−n2 | ≦ 0.03, both refractive indexes n1 and n2 can be made as close as possible to the same refractive index n.

Accordingly, the difference in optical refractive index is | n1−n2 | <0.03, or | n1−n2 | ≦ 0.03, or 0 <| n1−n2 | <0.03, or 0 <| An optical path of light passing through the lens structure of the present invention in which the lens array part 1 (lens peak part side) and the lens base part 2 with n1 -n2 | When obtaining the convergent light convergence width T, a conventional light diffusive lenticular lens sheet in which the lens array portion 1 (lens crest portion side) and the lens base portion 2 are integrally formed using a resin having a light refractive index n. The following relational expression (the sheet thickness t of the lenticular lens sheet A (from the apex of the crest of the lens to the light diffusion surface) for obtaining the light path of the lens structure and the light convergence width T converged on the light diffusion surface 3 Distance), lens pitch P (stripe width) of lens array unit 1, lens Radius of curvature R (O is the center of radius), distance f from the apex of the peak of the lens to the light convergence surface (focal length of the lenticular lens),
f = t = [n / (n−1)] × R
It is possible to easily obtain and set using.

  Accordingly, the lens array portion 1 (lens crest portion side) and the lens base portion 2 made of synthetic resin are bonded to each other, and a light diffusing lenticular lens sheet A having a light diffusing surface and a black stripe on the light converging side. Is easy to manufacture the lenticular lens sheet A capable of forming light-converging lines that are as thin as possible in the direction of each lens stripe on the light diffusion surface 3 of the lenticular lens sheet A.

Further, the width T of the light transmitting portion 5 (lens opening portion) of the light diffusing lenticular lens sheet A made of a bonded sheet obtained by bonding a lens array portion made of a synthetic resin and a base material portion can be made as thin as possible. From the relationship between the pitch P for each lens array 1 shown in FIG. 1 and the width B (B = B1 + B2) of the black stripe 4 for each lens array 1,
Br = B / P = (B1 + B2) / P
The high black stripe ratio Br required in the above can be obtained, and the light gain sufficient for the screen exit light (observation image light) that is diffused on the light diffusion surface and emitted from the thin light transmission portion, and the viewing field angle As a result, orientation characteristics can be obtained.

  Embodiments of the light diffusing lenticular lens sheet of the present invention will be described in detail below based on the drawings.

  FIG. 1 is a partial sectional side view of a light diffusing lenticular lens sheet A according to the present invention, and FIG. 2 is a partial plan view thereof. The lens array portion 1 is made of a transparent synthetic resin and is made of a transparent synthetic resin. In the stripe direction of the lens array unit 1, the light diffusion surface 3 provided with diffusibility by processing the lens substrate unit 2 surface opposite to the lens array unit 1 into a fine uneven surface. And a black stripe 4 provided for each lens crest of the lens array unit 1 and a light transmission part 5 provided in the center of the black stripe 4 for each lens crest.

The lenticular lens sheet A imparted with the light diffusibility is disposed on the screen front side of the image projection side of the rear projection screen with the light diffusion surface 3 in front, and the rear side of the rear projection screen (optical image) On the projection side), a Fresnel lens sheet made of synthetic resin for converting an optical image projected from the projection projector into parallel light is arranged.

  The light-diffusing lenticular lens sheet of the present invention is a sheet having a bonded structure in which the lens array portion 1 and the lens base portion 2 are bonded together, as shown in the side sectional view of FIG. 1 and the plan view of FIG. Furthermore, the surface in contact with the surface of the Fresnel lens sheet is provided with a lenticular lens array portion 1 having a ridge-like shape having a fine planar shape and a cross-sectional shape having the same pitch P, and the other flat surface. Includes a light diffusing surface 3 having a rough rough surface.

  A black stripe 4 (light-absorbing black or dark light-shielding pattern) having a predetermined width is formed on the light diffusion surface 3 facing the valley of the lens array unit 1. A light transmissive portion 5 (lens opening) having a predetermined width is formed on the light diffusion surface 3 corresponding to the light converging portion of parallel light incident on the lens array portion 1 facing the apex.

  The black stripe 4 is provided to prevent a decrease in contrast of the projected image due to the incidence of environmental noise light (external light) on the screen observation surface and difficulty in observing the projected image observed on the screen surface. ing.

  In FIG. 1, t is the sheet thickness of the lenticular lens sheet A (distance from the apex of the peak portion of the lens to the light diffusion surface), P is the lens pitch (stripe width) of the lens array unit 1, and R is the lens curvature radius ( O is the center of curvature radius), and f is the distance from the apex of the crest of the lens to the light convergence surface (focal length of the lenticular lens).

  In FIG. 1, T is the width of the light transmitting portion 5 (lens opening) of the light diffusing lenticular lens sheet A, and B1 is the black stripe 4 on one side across the light transmitting portion 5 for each lens array 1. The width B2 is the width of the black stripe 4 on the other side across the light transmitting portion 5 for each lens array 1, and the total width of the black stripe 4 for each lens array 1 is B1 + B2.

  The light diffusive lenticular lens sheet A of the present invention is composed of a laminated sheet in which a lens array portion 1 and a lens base portion 2 made of synthetic resin are bonded to each other on a bonding surface 6.

  In the present invention, the relationship between the optical refractive index n1 of the resin forming the lens array portion 1 and the optical refractive index n2 of the resin forming the lens substrate portion 2 is expressed as | n1−n2 | <0.03 or , | N1 −n2 | ≦ 0.03, and the absolute value of the difference in refractive index between the optical refractive indexes n1 and n2 is 0 or more and ± 0.03 or less, and is as close to 0 as possible. It is set.

  In another embodiment, the light diffusive lenticular lens sheet A composed of a bonded sheet in which the lens array unit 1 and the lens base member 2 are bonded to each other on the bonding surface 6 is obtained by combining the lens array unit 1 with the lens array unit 1. The relationship between the light refractive index n1 of the resin to be formed and the light refractive index n2 of the resin forming the lens base portion 2 is 0 <| n1−n2 | <0.03 or 0 <| n1−n2 | ≦ 0.03, and the absolute value of the difference in refractive index between the optical refractive indexes n1 and n2 is larger than 0 and ± 0.03 or less, and is set as close to 0 as possible. .

  In the present invention, for example, about 1.5 is appropriate as the light refractive index n2 of the resin forming the lens base portion 2, and as the light refractive index n1 of the resin forming the lens array portion 1, A suitable range is 1.47 to 1.53, or about 1.47 to 1.49, and about 1.51 to 1.53.

  The lens array portion 1 and the lens base portion 2 of the light diffusing lenticular lens sheet A of the present invention may be composed of separate synthetic resin materials or the same synthetic resin material.

  In addition, the light diffusing lenticular lens sheet A according to the present invention is formed by using a transparent thermoplastic resin to form the lens array portion 1 and the lens base portion 2 into a film and sheet by plastic melt extrusion molding, respectively. It may be an extrusion laminating method in which it is extruded and laminated to form a single piece, or the lens array part 1 and the lens base part 2 are injected into a mold using an ultraviolet curable resin (UV curable resin). A casting molding method may be used.

  The optical refractive index and refractive index difference of the synthetic resin used for the lens array portion 1 and the lens base portion 2 of the light diffusing lenticular lens sheet A of the present invention, and the optical gain (total light transmittance) (lens array portion) Table 1 below shows the relationship between the light quantity of the emitted light L3 (observation image light) emitted from the light transmitting portion 5 and the light quantity of the parallel light L1 incident from 1.

表１より、実施例２に示すようにレンズアレイ部１の光屈折率ｎ1 ＝１．５、レンズ基材部２の光屈折率ｎ2 ＝１．５、屈折率差＝０とした場合、８１％の高い光利得が得られ、良好な結果が得られた。また、実施例１に示すようにレンズアレイ部１の光屈折率ｎ1 ＝１．４８、レンズ基材部２の光屈折率ｎ2 ＝１．５、屈折率差＝０．０２とした場合、７８％の高い光利得が得られ、良好な結果が得られた。また、実施例３に示すようにレンズアレイ部１の光屈折率ｎ1 ＝１．５３、レンズ基材部２の光屈折率ｎ2 ＝１．５、屈折率差＝０．０３とした場合、７０％の高い光利得が得られ、良好な結果が得られた。

From Table 1, as shown in Example 2, when the light refractive index n1 of the lens array portion 1 = 1.5, the light refractive index n2 of the lens substrate portion 2 = 1.5, and the refractive index difference = 0, 81 % High optical gain was obtained, and good results were obtained. Further, as shown in Example 1, when the light refractive index n1 of the lens array portion 1 = 1.48, the light refractive index n2 of the lens base portion 2 = 1.5, and the refractive index difference = 0.02, 78 % High optical gain was obtained, and good results were obtained. Further, as shown in Example 3, when the optical refractive index n1 of the lens array portion 1 is 1.53, the optical refractive index n2 of the lens substrate portion 2 is 1.5, and the refractive index difference is 0.03, 70 % High optical gain was obtained, and good results were obtained.

The expanded side sectional view explaining an example of the light diffusive lenticular lens sheet of the present invention. The top view explaining an example of a general light diffusive lenticular lens sheet. The sectional side view explaining an example of the process of pattern-forming a black stripe using a general light diffusive lenticular lens sheet. The expanded sectional side view explaining an example of a general light diffusive lenticular lens sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lens array part 2 ... Lens base material part 3 ... Light diffusion surface 4 ... Black stripe 5 ... Light transmission part 6 ... Bonding surface 10 ... Lenticular lens sheet 11 ... Black photosensitive resin layer 11a ... Exposure part A ... Light diffusion Lenticular lens sheet B1, B2 ... black stripe width L1 ... incident light (projection light) L2 ... refracted light L3 ... outgoing light (observation image light)
B1, B2 ... black stripe width O ... radius of curvature center P ... lens pitch t ... lens sheet thickness R ... lens radius of curvature S ... light converging part T ... light transmitting part width (light converging width)

Claims (2)

A method for producing a light diffusing lenticular lens sheet constituting a rear projection screen,
A base material part;
On one surface of the substrate part,
When the light refractive index n1 of the resin forming the lens array part made of an ultraviolet curable resin and the light refractive index n2 of the resin forming the base part are given, | n1-n2 | <0.03 or | forming the lens array portion satisfying the relationship of n1−n2 | ≦ 0.03 by casting an ultraviolet curable resin into a mold,
Forming a light diffusing surface consisting of fine irregular surfaces on the surface of the back surface side of the surface to which the lens array portion of the base material portion is provided,
Furthermore, a photodegradable photoresist liquid colored with a black pigment is applied to the light diffusing surface, dried and solidified to form a black photosensitive resin layer,
Irradiating parallel light by ultraviolet light from the lens array portion side, exposing the black photosensitive resin layer of the light diffusion surface with ultraviolet light converged to a predetermined stripe width in the lens stripe direction on the light diffusion surface side, By developing and removing the exposed portion facing each crest of the lens array portion with an alkaline developer, by pattern exposure method of black stripes,
A method for producing a light diffusive lenticular lens sheet, wherein the total light transmittance is 70% or more and 81% or less. A method for producing a light diffusing lenticular lens sheet constituting a rear projection screen,
A base material part;
On one surface of the substrate part,
0 <| n1-n2 | <0.03, where the light refractive index n1 of the resin forming the lens array part made of ultraviolet curable resin and the light refractive index n2 of the resin forming the base part are , 0 <| n1-n2 | ≦ 0.03, the lens array portion is formed by casting a UV curable resin into a mold,
Forming a light diffusing surface consisting of fine irregular surfaces on the surface of the back surface side of the surface to which the lens array portion of the base material portion is provided,
Furthermore, a photodegradable photoresist liquid colored with a black pigment is applied to the light diffusing surface, dried and solidified to form a black photosensitive resin layer,
Irradiating parallel light by ultraviolet light from the lens array portion side, exposing the black photosensitive resin layer of the light diffusion surface with ultraviolet light converged to a predetermined stripe width in the lens stripe direction on the light diffusion surface side, By developing and removing the exposed portion facing each crest of the lens array portion with an alkaline developer, by pattern exposure method of black stripes,
A method for producing a light diffusive lenticular lens sheet, wherein the total light transmittance is 70% or more and 81% or less.

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