JP2007008052A - Manufacturing method of lens substrate, lens substrate and rear type projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a lens substrate capable of effectively manufacturing the lens substrate having high reliability and preferably usable for a rear type projector, to provide the lens substrate having high reliability and preferably usable for the rear type projector, and to provide a rear type projector having the lens substrate. <P>SOLUTION: The manufacturing method of the lens substrate comprises a composition supply process of supplying a fluid composition between the first mold and the second mold, and an energy ray irradiation process of curing the composition by casting an energy ray to the composition from the surface in contact with the first mold wherein either one of the first mold and the second mold has unevenness corresponding to the surface configuration of a micro lens, the other mold has unevenness corresponding to the surface configuration of a Fresnel lens, and the first mold is composed of an energy ray-transmissive material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens substrate manufacturing method, a lens substrate, and a rear projector.

In recent years, the demand for rear projectors is increasing as a display suitable for home theater monitors, large-screen televisions, and the like.
A transmissive screen used in a rear projector includes a lens substrate such as a Fresnel lens, a lenticular lens, or a microlens.
As a method of manufacturing a lens substrate (lens sheet) having a large number of irregularities on the surface, such as a Fresnel lens substrate, a lenticular lens substrate, a microlens substrate, etc., generally, a method of injection molding a synthetic resin, a resin plate, A press molding method has been used in which the surface unevenness of the mold is transferred by bringing the mold into contact with the mold and heating and pressing it.

  However, when an injection molding method or a press molding method is used, it is difficult to manufacture a large lens substrate (for example, a lens substrate having a diagonal length of 100 cm or more). Only applicable. In addition, in the press molding method, since the heating and cooling cycle of the resin plate and the mold takes a long time, a large number of molds are necessary for mass production of the lens substrate, and in order to manufacture a large lens substrate. There was a problem that the production equipment was very expensive.

  In order to solve such problems, an ultraviolet curable resin solution is injected between a mold and a transparent resin plate or film (hereinafter simply referred to as “resin film”) and then irradiated with ultraviolet rays. A method of curing the resin solution is performed (for example, see Patent Document 1). In such a method, a mold made of a metal material is used as a mold from the viewpoint of strength and the like. Then, after filling the ultraviolet curable resin, the entire surface is exposed from the resin film side in a state where the resin film is attached to the mold, and the ultraviolet curable resin is cured.

  Such a method can cope with the production of a relatively large lens substrate (lens sheet) and can shorten the time required for molding, but has the following problems. It was. That is, in order to reliably give the irradiated ultraviolet energy to the ultraviolet curable resin, no load was applied to the resin film during the irradiation of the ultraviolet rays. For this reason, the outer surface of the resin film cannot be maintained flat when irradiated with ultraviolet rays (the resin film undulates), and the obtained lens substrate is opposite to that in contact with the mold. The flatness of the surface side is low, that is, it has an unintentional thickness variation. Further, in some cases, bubbles may enter between the ultraviolet curable resin and the resin film during the irradiation of ultraviolet rays (to create voids). From the above, the obtained lens substrate has low reliability and inferior optical characteristics.

  In order to solve the above problems, it is conceivable to use a plate member having low flexibility as a resin film. In such a case, a lens substrate obtained by curing an ultraviolet curable resin. The (lens sheet) becomes thick. When the thickness of the lens substrate is increased in this way, it is not preferable from the viewpoint of optical characteristics, for example, it is necessary to increase the focal length of the lens, and a device (such as a rear projector) including the lens substrate is increased in size and the device is thin. It is also disadvantageous for the improvement. In addition, it is conceivable to reduce the thickness of the lens substrate by, for example, polishing the plate-like member after curing the ultraviolet curable resin. Is significantly reduced.

  In addition, transmissive screens used in rear projectors use lenticular lens substrates and microlens substrates for the purpose of improving viewing angle characteristics. Such lens substrates (lenticular lens substrates, microlens substrates) are used. If only is used, light is diffused more than necessary, and it becomes difficult to obtain sufficient luminance in the projected image, and the brightness at each part on the screen is greatly different. Therefore, a transmissive screen usually has a configuration in which light from a light source is once converted into parallel light using a Fresnel lens substrate and then the parallel light is diffused by a lenticular lens substrate or a microlens substrate. It was. However, in such a configuration, the number of members constituting the transmissive screen increases, which is disadvantageous for downsizing and thinning of the device. In addition, as described above, since it has a plurality of lens substrates, it is difficult to sufficiently increase the brightness of the image at the front position with respect to the screen unless they are arranged in parallel reliably. As a result, the variation in viewing angle characteristics increases, and a suitable image cannot be projected.

JP 2004-322566 A (paragraph number 0017)

  An object of the present invention is to provide a method of manufacturing a lens substrate that can efficiently manufacture a lens substrate that has high reliability and can be suitably applied to a rear projector, and that has high reliability, and It is another object of the present invention to provide a lens substrate that can be suitably applied to a rear projector, and to provide a rear projector including the lens substrate.

Such an object is achieved by the present invention described below.
The method of manufacturing a lens substrate according to the present invention includes a composition supplying step of supplying a fluid composition between the first mold and the second mold,
An energy ray irradiating step for curing the composition by irradiating the composition with an energy ray from the surface side in contact with the first mold;
One of the first mold and the second mold has irregularities corresponding to the surface shape of the microlens, and the other has irregularities corresponding to the surface shape of the Fresnel lens And
The first mold is characterized by using a material made of a material having transparency to the energy beam.

  Accordingly, it is possible to provide a method for manufacturing a lens substrate that can efficiently manufacture a lens substrate that has high reliability and can be suitably applied to a rear projector. In addition, compared to the case of using multiple lens substrates (a lens substrate with a microlens (microlens substrate) and a lens substrate with a Fresnel lens (Fresnel lens substrate)), the use efficiency of light is superior. It can be.

In the lens substrate manufacturing method of the present invention, the composition supplying step is performed by pressing the composition with the second mold after supplying the composition onto the first mold. preferable.
Thereby, in the manufactured lens substrate, it is possible to more effectively prevent bubbles from entering or causing unintended defects.

In the method of manufacturing a lens substrate according to the present invention, the composition supplying step includes a plate-like or film-like substrate disposed between the first mold and the second mold, and the substrate It is preferable to carry out in a state where the composition is disposed on both sides of the film.
Thereby, the stability of the shape of the manufactured lens substrate can be made particularly excellent.

In the method for producing a lens substrate of the present invention, in the composition supplying step, after supplying the composition on the first mold, a plate-like or film-like substrate is installed on the surface of the composition, Then, it is preferable to carry out by supplying the composition to the surface of the base material and further pressing the composition on the base material with the second mold.
Thereby, in the manufactured lens substrate, the stability of the shape of the manufactured lens substrate is made particularly excellent while effectively preventing bubbles from entering or causing unintended defects. be able to.

In the method for manufacturing a lens substrate according to the present invention, it is preferable that the energy beam is ultraviolet light.
Thereby, a lens substrate can be more easily manufactured with simple equipment. In addition, the degree of freedom in selecting the composition can be increased, and the occurrence of adverse effects on members such as devices used in manufacturing the lens substrate can be more effectively prevented.

In the lens substrate manufacturing method of the present invention, it is preferable that a step of removing the first die and the second die is provided after the energy ray irradiation step.
Accordingly, the molds (first mold and second mold) can be repeatedly used for manufacturing the lens substrate, which can contribute to improvement of the productivity of the lens substrate and reduction of manufacturing cost.
In the method for manufacturing a lens substrate of the present invention, it is preferable that the first mold is made of a glass material.
In general, the glass material is excellent in transmittance of various energy rays and has excellent stability with respect to various energy rays. Moreover, the glass material is excellent from the viewpoint of mechanical strength, shape stability, and the like. Therefore, by using a mold made of a glass material, a lens substrate having a fine structure can be manufactured with excellent dimensional accuracy and high productivity.

In the method for manufacturing a lens substrate according to the present invention, it is preferable that the composition is mainly composed of an acrylic resin.
Thereby, in an energy ray irradiation process, while being able to harden a composition efficiently, the reliability and optical characteristic of the lens substrate manufactured can be made especially excellent.

In the manufacturing method of the lens substrate of the present invention, it is preferable that the radius of curvature of the microlens is 5 to 300 μm.
As a result, the brightness of the projected image can be made particularly high while sufficiently improving the viewing angle characteristics of the manufactured lens substrate.
In the method for manufacturing a lens substrate according to the present invention, it is preferable that the microlens has a flat shape in which the vertical width when the lens substrate is viewed in plan is smaller than the horizontal width.
Thereby, it is possible to effectively prevent the occurrence of moire due to light interference.

In the lens substrate manufacturing method of the present invention, the thickness of the lens substrate is preferably 0.5 to 5 mm.
Thus, even a relatively thin lens substrate can be suitably manufactured according to the present invention. Further, when the thickness of the lens substrate is a value within the above range, the optical characteristics of the lens substrate can be made particularly excellent.

The lens substrate of the present invention is manufactured using the method of the present invention.
Thereby, a highly reliable lens substrate can be provided.
A rear projector according to the present invention includes the lens substrate according to the present invention.
Thereby, a highly reliable rear type projector can be provided.

Hereinafter, a lens substrate manufacturing method, a lens substrate, and a rear projector according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
In the present invention, the term “substrate” refers to a concept that includes substantially no flexibility, including a relatively thick plate shape, a film shape (sheet shape), and the like. Point to.
Although the use of the lens substrate of the present invention is not particularly limited, in the present embodiment, the lens substrate will be described as being mainly used as a member constituting a rear projector.

[First Embodiment]
Hereinafter, a first embodiment of a lens substrate and a method of manufacturing the lens substrate of the present invention will be described.
First, the configuration of the lens substrate of this embodiment will be described.
FIG. 1 is a schematic longitudinal sectional view showing a first embodiment of the lens substrate of the present invention, and FIG. 2 is a plan view from the surface side where the microlenses of the lens substrate shown in FIG. 1 are provided. In the following description, the left side in FIG. 1 is referred to as “(light) incident side”, and the right side is referred to as “(light) emission side”. In the present invention, unless otherwise specified, the “(light) incident side” and the “(light) output side” are the “incident side” of light for obtaining image light (video light), respectively. ”And“ outgoing side ”, not“ incident side ”or“ outgoing side ”of external light or the like. In addition, each drawing referred to in the present specification emphasizes a part of the configuration, such as a microlens and a colored portion, and does not reflect actual dimensions.

  The lens substrate 1 is a member constituting a rear projector 300 to be described later, and has a large number of microlenses 11 on one surface (first main surface) side, and the other surface (second main surface). ) Side has a Fresnel lens 12. That is, the lens substrate 1 has a configuration in which a microlens substrate and a Fresnel lens substrate are integrated. A colored portion (external light absorbing portion) 13 is provided on the light incident side of the lens substrate 1 (that is, the light incident side of the microlens 11), and other portions are non-colored portions 14. It has become. The coloring part 13 will be described in detail later.

The lens substrate 1 is usually composed mainly of a material having transparency.
The constituent material of the lens substrate 1 is not particularly limited, but usually the lens substrate 1 is mainly composed of a resin material or a glass material (both of which usually have a refractive index of light larger than air), and has a predetermined refractive index. It is comprised with the transparent material which has.
Specific examples of the constituent material of the lens substrate 1 include polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified polyolefin, polyvinyl chloride, poly Vinylidene chloride, polystyrene, polyamide (eg, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, nylon 6-66), polyimide, polyamideimide, polycarbonate (PC) , Poly- (4-methylpentene-1), ionomer, acrylic resin, acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene copolymer (AS resin), butadiene-styrene copolymer Polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyester such as polycyclohexane terephthalate (PCT), polyether, polyether Ketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal (POM), polyphenylene oxide, modified polyphenylene oxide, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, aromatic polyester (liquid crystal polymer), Polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin, polyvinyl chloride, poly Various thermoplastic elastomers such as tan, polyester, polyamide, polybutadiene, trans polyisoprene, fluororubber, chlorinated polyethylene, epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester, silicone Resins, urethane resins, etc., or various resin materials such as copolymers, blends, polymer alloys, etc., soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, none Examples include alkali glass. Of these, polystyrene, polycarbonate, polyethylene terephthalate, and acrylic resins are preferable from the viewpoints of transparency, processability, and the like, and acrylic resins are particularly preferable. Acrylic resin has excellent transparency, heat resistance, light resistance, workability, dimensional accuracy when molded, mechanical strength, etc., and has an optimal refractive index. . Further, in the lens substrate manufacturing method as described later, the lens substrate can be more easily manufactured with simple equipment. In addition, the degree of freedom in selecting the composition can be increased, and the occurrence of adverse effects on members such as devices used in manufacturing the lens substrate can be more effectively prevented.

  As an acrylic resin, for example, an acrylic resin having acrylic acid or a derivative thereof (for example, acrylic ester) as a constituent monomer, a methacrylic resin having a constituent monomer of methacrylic acid or a derivative thereof (for example, methacrylic ester), for example. Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid ester-methacrylic acid ester copolymer, styrene-α-chloroacrylic acid methyl copolymer, styrene-acrylonitrile-acrylic acid A copolymer containing (meth) acrylic acid such as an ester copolymer or a derivative thereof as a constituent monomer can be used, and one or more selected from these can be used in combination.

  The material constituting the lens substrate 1 (solidified material) generally has a larger absolute refractive index than various gases (the atmosphere in which the lens substrate 1 is used), but the specific value of the absolute refractive index is 1.45 or more, preferably 1.46 to 1.75, more preferably 1.47 to 1.60, and more preferably 1.48 to 1.55. Most preferred. When the absolute refractive index of the constituent material of the lens substrate 1 is a value within the above range, the viewing angle characteristic can be made particularly excellent while the utilization efficiency of light (incident light) is made particularly excellent.

In the present embodiment, the lens substrate 1 includes a base material (lens substrate base material) 15 and a curing portion 16 formed by curing by irradiation with energy rays.
The base material 15 is usually composed mainly of the material as described above, but may contain other components.
Moreover, the hardening part 16 is formed by hardening by irradiation of the energy beam mentioned later. Among the materials described above, examples of materials that can be suitably cured by irradiation with energy rays (for example, ultraviolet rays) include acrylic resins.

The lens substrate 1 is provided on the light incident side, and is formed of a coloring portion 13 made of a material containing a colorant, and a material which is provided on the light emission side of the coloring portion 13 and does not substantially contain a colorant. It has the non-colored part 14 comprised.
The coloring unit 13 can sufficiently transmit the light incident from the incident side, and external light (for example, external light incident unintentionally from the light emitting side or the like) is reflected on the light emitting side. It has a function to prevent. By having such a colored portion 13 together with the non-colored portion 14, an image having excellent contrast can be obtained.

  Although the thickness of the coloring part 13 is not specifically limited, It is preferable that it is 0.1-50 micrometers, It is more preferable that it is 0.2-20 micrometers, It is further more preferable that it is 0.3-10 micrometers. When the thickness of the colored portion 13 is a value within the above range, the transmittance of light to be incident from the light incident side is particularly high, while being opposite to the light incident side to be incident on the lens substrate 1. The light incident from the side (external light) can be efficiently attenuated to more reliably prevent the influence of external light. As a result, the contrast of the image formed by the light transmitted through the lens substrate 1 can be made particularly excellent. On the other hand, when the thickness of the colored portion 13 is less than the lower limit, it is difficult to sufficiently prevent reflection of external light (external light incident from the side opposite to the light incident side). There is a possibility that the effect of improving the contrast cannot be obtained sufficiently. Further, when the thickness of the colored portion 13 exceeds the upper limit, the transmittance of incident light is reduced, and sufficient luminance cannot be obtained in the obtained image, and as a result, the contrast of the image may be insufficient. There is.

  The color of the colored portion 13 is not particularly limited, but a colorant based on blue, mixed with red, brown, or yellow is used. The appearance is achromatic and black, and the balance of the three primary colors of light from the light source is controlled. It is preferable to selectively absorb or transmit light having a specific wavelength. Thereby, reflection of external light is prevented, the color tone of the image formed by the light transmitted through the lens substrate 1 is accurately expressed, the color coordinates are wide (the range of color tone expression is sufficiently wide), and deeper Since black can be expressed, the contrast can be made particularly excellent as a result.

  As a coloring agent which comprises the coloring part 13, various dyes, various pigments, etc. can be used, for example. Examples of such pigments and dyes include carbon black, spirit black, lamp black (CI No. 77266), magnetite, titanium black, chrome lead, cadmium yellow, mineral fast yellow, navel yellow, and naphthol yellow S. , Hansa Yellow G, Permanent Yellow NCG, Chrome Yellow, Benzidine Yellow, Quinoline Yellow, Tartrazine Lake, Red Mouth Lead, Molybdenum Orange, Permanent Orange GTR, Pyrazolone Orange, Benzidine Orange G, Cadmium Red, Permanent Red 4R, Watching Red Calcium salt, eosin lake, brilliant carmine 3B, manganese purple, fast violet B, methyl violet lake, bitumen, cobalt blue, al Reblue Lake, Victoria Blue Lake, First Sky Blue, Indanthrene Blue BC, Ultramarine, Aniline Blue, Phthalocyanine Blue, Calco Oil Blue, Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake, Phthalocyanine Green, Final Yellow Green G, Rhodamine 6G, quinacridone, rose bengal (C.I. No. 45432), C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modern Tread 30, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 184, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modern Blue 7, C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 5: 1, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Basic Green 6, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 180, C.I. I. Pigment Yellow 162, nigrosine dye (CI No. 50415B), metal complex dye, silica, aluminum oxide, magnetite, maghemite, various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, Examples thereof include metal oxides such as magnesium oxide, and magnetic materials containing magnetic metals such as Fe, Co, and Ni, and one or more of these can be used in combination.

As described above, the lens substrate 1 includes a large number of microlenses 11 on the first main surface side.
Thus, since the lens substrate is provided with a microlens, the viewing angle characteristics when the lens substrate is applied to a rear projector or the like are particularly excellent (viewing angle characteristics in the vertical and horizontal directions). Can be particularly excellent).

  Further, if the lens substrate is provided with a microlens, the following effects can be obtained at the time of manufacture. That is, the lens substrate including the microlens has two-dimensionally minute unevenness. When such a lens substrate is manufactured by a conventional method, it is difficult to reliably supply the composition into the minute concave portion of the mold, and there is a problem that the microlens is not formed at a site where the microlens is to be formed. It was easy to occur. On the other hand, in the manufacturing method of the present invention, such a lens substrate can be manufactured easily and reliably as having a desired shape.

  In the present embodiment, the microlens 11 is provided as a convex lens. Thereby, the reflectance of the external light from the light emission surface side can be effectively reduced (intentional reflection of external light can be effectively prevented), and as a result the projected image The contrast can be further improved. In particular, in the present embodiment, since the colored portion 13 having a function of absorbing outside light is provided, the effect of the microlens 11 being formed as a convex lens and the effect of having the colored portion 13 are synergistic. Particularly effective. If the microlens 11 is a convex lens, the microlens forming mold 6 that can be easily manufactured by etching in a manufacturing method as described later can be suitably used as the first mold.

  Further, in the present embodiment, the microlens 11 has a flat shape (substantially oval or substantially bowl-shaped) whose horizontal width when the lens substrate 1 is viewed in plan is larger than the vertical width. When the microlens 11 has such a shape, the viewing angle characteristics can be made particularly excellent while effectively preventing the occurrence of inconvenience such as moire. In particular, both the horizontal and vertical viewing angle characteristics can be improved.

When the length in the minor axis direction (vertical direction) of the microlens 11 in plan view is L ₁ [μm] and the length in the major axis direction (lateral direction) is L ₂ [μm], 0.10 ≦ The relationship of L ₁ / L ₂ ≦ 0.99 is preferably satisfied, the relationship of 0.50 ≦ L ₁ / L ₂ ≦ 0.95 is more preferable, and 0.60 ≦ L ₁ / L ₂ is satisfied. More preferably, the relationship of ≦ 0.80 is satisfied. By satisfying the relationship as described above, the effects as described above become more remarkable.

  The length in the minor axis direction of the microlens 11 when viewed in plan is preferably 10 to 500 μm, more preferably 30 to 300 μm, and still more preferably 50 to 100 μm. When the length of the microlens 11 in the short axis direction is a value within the above range, it is possible to obtain a sufficient resolution in the projected image while effectively preventing the occurrence of inconvenience such as moire. The productivity of the substrate 1 can be further increased.

  Further, the length of the microlens 11 in the major axis direction when viewed in plan is preferably 15 to 750 μm, more preferably 45 to 450 μm, and further preferably 75 to 150 μm. When the length of the microlens 11 in the short axis direction is a value within the above range, it is possible to obtain a sufficient resolution in the projected image while effectively preventing the occurrence of inconvenience such as moire. The productivity of the substrate 1 can be further increased.

  Further, the radius of curvature of the microlens 11 in the minor axis direction (hereinafter also simply referred to as “the radius of curvature of the microlens 11”) is preferably 5 to 250 μm, more preferably 15 to 150 μm, 25 More preferably, it is ˜50 μm. When the radius of curvature of the microlens 11 is a value within the above range, the viewing angle characteristics can be made particularly excellent. In particular, both the horizontal and vertical viewing angle characteristics can be improved.

  The focal length of the microlens 11 in the minor axis direction (hereinafter also simply referred to as “the focal length of the microlens 11”) is not particularly limited, but is preferably 20 to 400 μm, and preferably 30 to 200 μm. Is more preferable, and it is further more preferable that it is 40-70 micrometers. When the focal length of the microlens 11 is a value within the above range, the viewing angle characteristics can be made particularly excellent. In particular, both the horizontal and vertical viewing angle characteristics can be improved.

  The plurality of microlenses 11 are arranged in a staggered pattern. By arranging the microlenses 11 in this way, it is possible to effectively prevent inconveniences such as moire. On the other hand, for example, if the microlenses are arranged in a square lattice or the like, it is difficult to sufficiently prevent the occurrence of inconvenience such as moire. In addition, when the microlenses are randomly arranged, it becomes difficult to sufficiently increase the occupation ratio of the microlenses in the effective area where the microlenses are formed, and the light transmittance (light utilization efficiency) of the lens substrate is sufficient. However, it is difficult to increase the brightness and the resulting image becomes dark.

As described above, the microlenses 11 are arranged in a staggered pattern when the lens substrate 1 is viewed in plan view, but are adjacent to the first row 17 composed of a plurality of microlenses 11. It is preferable that the second row 18 is shifted by a half pitch in the vertical direction. As a result, it is possible to more effectively prevent the occurrence of moire due to light interference and to make the viewing angle characteristics particularly excellent.
As described above, by strictly defining the shape, arrangement method, occupation ratio, etc. of the microlens, the viewing angle characteristics should be particularly excellent while effectively preventing the occurrence of moire due to light interference. Can do.

Further, when the lens substrate 1 is viewed in plan from the light incident surface side (direction shown in FIG. 2), the occupation ratio of the microlenses 11 is 90% or more in the effective region where the microlenses 11 are formed. Preferably, it is 96% or more, more preferably 97 to 99.5%. When the occupation ratio of the microlenses 11 is 90% or more, the straight light passing through other than the microlenses 11 can be further reduced, and the light utilization efficiency can be further improved. Note that the occupation ratio of the microlens 11 is the center (center of the top) 111 of the microlens 11 when viewed in plan and the central portion of the portion adjacent to the microlens 11 where the microlens 11 is not formed. In the line segment to be connected, the ratio of the length L ₃ [μm] of the part where the microlens 11 is formed to the length L ₄ [μm] of the line segment (L ₃ / L ₄ × 100 [%]) (See FIG. 2).

In the present embodiment, each microlens 11 is formed as a convex lens protruding to the incident side. Therefore, the light incident on the lens substrate 1 is once converged in the lens substrate 1 by the microlens 11 and then diffused. Thus, if the light diffused by the microlens 11 is emitted from the lens substrate 1 as it is, it becomes excessively diffused, making it difficult to obtain sufficient luminance in the projected image. In addition, the projected image is greatly different in brightness at each part. In order to solve such a problem, a Fresnel lens 12 is provided on the light exit surface side of the lens substrate 1. By having such a Fresnel lens 12, light excessively diffused by the microlens 11 can be appropriately converged, and variations in brightness at each part on the light emission side can be reduced. In addition, since the microlens 11 and the Fresnel lens 12 are provided on opposite surfaces of the same substrate, the lens substrate 1 can be used as a transmissive screen in, for example, a rear projector as described later. That is, the transmission screen can be configured by a single lens substrate. In addition, since the microlens 11 and the Fresnel lens 12 are provided on the same substrate, it is possible to reduce the number of constituent members of the device such as a rear projector, which can contribute to downsizing and thinning of the device. In addition, since the microlens 11 and the Fresnel lens 12 are provided on the same substrate, it is not necessary to align the microlens and the Fresnel lens in the apparatus (in the rear projector). The brightness of the image can be made sufficiently high, and the variation in viewing angle characteristics in each direction can be made sufficiently small.
The Fresnel lens 12 has a prism shape that is formed substantially concentrically.
The pitch of the Fresnel lens 12 is not particularly limited, but is preferably 50 to 200 μm, and more preferably 60 to 180 μm. Thereby, the moire phenomenon due to the pitch interference between the microlens 11 and the Fresnel lens 12 can be more effectively prevented.

The transmittance of light incident from the surface side (light incident side) of the lens substrate 1 on which the colored portion 13 is provided is A [%], and the surface side opposite to the surface on which the colored portion 13 of the lens substrate 1 is provided. When the transmittance of light incident from (light emitting side) is B [%], it is preferable to satisfy the relationship of B / A ≦ 0.8, and satisfy the relationship of B / A ≦ 0.75. It is more preferable to satisfy the relationship of 0.01 ≦ B / A ≦ 0.7. By satisfying such a relationship, the light use efficiency and the contrast of the obtained image can be made particularly excellent.
The light use efficiency of the lens substrate 1 (ratio of the light amount of light emitted from the exit surface side to the light amount of light incident from the entrance surface side of the lens substrate 1) is preferably 60% or more, and 70% or more. It is more preferable that it is 80 to 99%.

  By the way, by including a diffusing agent as a constituent material of the lens substrate, it is possible to improve the viewing angle characteristics, but on the other hand, the light use efficiency and the contrast of the obtained image are lowered. Therefore, the lens substrate 1 may include a diffusing material as a constituent material thereof, but the content of the diffusing material is preferably 30 wt% or less, more preferably 10 wt% or less, and a diffusing agent. More preferably, it does not contain. Even with such a configuration, according to the configuration described above, the viewing angle characteristics can be sufficiently improved. That is, according to the configuration as described above, the viewing angle characteristics, the light utilization efficiency, the image contrast, and the like can be simultaneously improved.

  The thickness of the lens substrate 1 as described above is preferably 0.5 to 5 mm, more preferably 1 to 4 mm, and still more preferably 2 to 3 mm. When the thickness of the lens substrate 1 is within the above range, the light utilization efficiency and the viewing angle characteristics can be made particularly excellent. In addition, such a relatively thin lens substrate has been difficult to accurately manufacture by the conventional method, but can be preferably manufactured by the method of the present invention described later. The thickness of the lens substrate 1 refers to the thickness from the top of the microlens 11 to the top of the Fresnel lens 12.

  The lens substrate 1 as described above may be used for any purpose, but preferably constitutes a rear projector as described later. More specifically, the lens substrate 1 preferably functions as a transmissive screen in a rear projector. As a result, the number of constituent members of the rear projector can be reduced, which can contribute to the downsizing and thinning of the apparatus. Further, since the lens substrate 1 has the microlens 11 and the Fresnel lens 12 on the same substrate, it is not necessary to align the microlens and the Fresnel lens in the rear projector, and it is easy and reliable. The luminance of the image can be made sufficiently high, and the variation in viewing angle characteristics in each direction can be made sufficiently small.

In particular, in this embodiment, the microlens 11 as a convex lens is provided on the light incident side, and the Fresnel lens 12 is provided on the light emission side. With such a configuration, the light utilization efficiency can be particularly improved. Further, as shown in the figure, the colored portion 13 is provided in the microlens 11 as a convex lens provided on the light incident side, so that the transmittance of incident light (light incident from the light incident side) is sufficiently increased. While making it excellent, it can make the absorption characteristics of outside light (for example, light incident unintentionally from the light exit side) particularly excellent, and the image contrast (especially bright room contrast) is particularly excellent Can be.
It should be noted that a transmissive screen of a rear projector as will be described later may be substantially constituted only by a lens substrate, or in addition to the lens substrate, other members (for example, protect the surface of the lens substrate). Protective layer, protective plate and the like).

Next, a method for manufacturing the above-described lens substrate will be described. Prior to that, a microlens forming mold as a first mold that can be suitably used for manufacturing the lens substrate, and a method for manufacturing the same will be described.
FIG. 3 is a schematic longitudinal sectional view showing a microlens forming mold (first mold) used for manufacturing the lens substrate, and FIG. 4 is a schematic showing a manufacturing method of the microlens forming mold shown in FIG. FIG. In the manufacture of the microlens forming mold, a large number of concave portions (microlens forming concave portions) are actually formed on the substrate. In the manufacturing of the lens substrate, actually, a large number of microlenses ( A convex lens) is formed here, but a part thereof is highlighted for easy understanding.

  The microlens forming mold (first mold) 6 is made of a material capable of transmitting energy rays, which will be described in detail later. The material that can be used as the microlens forming mold 6 differs depending on the type of energy rays used in the subsequent process, but examples of the constituent material of the microlens forming mold 6 include soda glass and crystalline glass. And glass materials such as quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass. Especially, as a constituent material of the mold 6 for forming a microlens, soda glass, crystalline glass (for example, neo-ceram), and alkali-free glass are preferable. Such a material is particularly excellent in stability with respect to various energy rays, is not likely to bend, and is not easily damaged. Further, it is easy to process and relatively inexpensive, which is advantageous from the viewpoint of manufacturing cost.

  The microlens forming mold 6 has a shape corresponding to the surface shape of the microlens 11 constituting the lens substrate 1 and is arranged in a plurality of recesses (microscopes) arranged in a manner corresponding to the arrangement manner of the microlenses 11. Lens-forming concave portions 61 are provided, and these concave portions 61 are generally substantially the same as the microlens 11 (the microlens is a convex portion while being a concave portion, and has a transferred shape). , Except for the positional relationship, it has the same shape (size) and arrangement method.

  More specifically, in the present embodiment, the concave portion (microlens forming concave portion) 61 has a flat shape (substantially oval, substantially bowl-shaped) having a horizontal width larger than the vertical width when the microlens forming die 6 is viewed in plan view. )have. Since the recess 61 has such a shape, it can be suitably used for manufacturing the lens substrate 1 that can effectively prevent the occurrence of inconvenience such as moire and can have particularly excellent viewing angle characteristics. it can.

When the length in the minor axis direction (longitudinal direction) of the recess 61 when viewed in plan is L ₁ [μm] and the length in the major axis direction (vertical direction) is L ₂ [μm], 0.1 ≦ L ₁ / L ₂ ≦ 0.99 is preferably satisfied, more preferably 0.5 ≦ L ₁ / L ₂ ≦ 0.95 is satisfied, and 0.6 ≦ L ₁ / L More preferably, the relationship ₂ ≦ 0.8 is satisfied. By satisfying the relationship as described above, the effects as described above become more remarkable.

  Further, the length in the minor axis direction of the recess 61 when viewed in plan is preferably 10 to 500 μm, more preferably 30 to 300 μm, and further preferably 50 to 100 μm. When the length of the concave portion 61 in the minor axis direction is a value within the above range, it is possible to obtain sufficient resolution in the projected image while effectively preventing the occurrence of inconvenience such as moire, and the lens substrate. The productivity of 1 (microlens forming mold 6) can be further increased.

  Further, the length in the major axis direction of the concave portion 61 when viewed in plan is preferably 15 to 750 μm, more preferably 45 to 450 μm, and further preferably 75 to 150 μm. When the length of the concave portion 61 in the minor axis direction is a value within the above range, it is possible to obtain sufficient resolution in the projected image while effectively preventing the occurrence of inconvenience such as moire, and the lens substrate. The productivity of 1 (microlens forming mold 6) can be further increased.

  Further, the radius of curvature of the recess 61 in the minor axis direction (hereinafter also simply referred to as “the radius of curvature of the recess 61”) is preferably 5 to 250 μm, more preferably 15 to 150 μm, and more preferably 25 to 50 μm. More preferably. When the radius of curvature of the recess 61 is a value within the above range, the viewing angle characteristic can be made particularly excellent. In particular, both the horizontal and vertical viewing angle characteristics can be improved.

Moreover, it is preferable that the depth of the recessed part 61 is 7-375 micrometers, It is more preferable that it is 22-225 micrometers, It is further more preferable that it is 37-75 micrometers. When the depth of the recess 61 is a value within the above range, the light utilization efficiency and the viewing angle characteristics in the lens substrate 1 can be made particularly excellent.
Further, when the depth of the recess 61 is D [μm] and the length of the recess 61 in the minor axis direction is S [μm], it is preferable that the relationship of 0.02 ≦ S / D ≦ 50 is satisfied. More preferably, the relationship of 0.1 ≦ S / D ≦ 1.40 is satisfied, and the relationship of 0.5 ≦ S / D ≦ 1.0 is more preferable. By satisfying such a relationship, the viewing angle characteristic can be made particularly excellent while effectively preventing the occurrence of moire due to light interference.

  The plurality of recesses 61 are arranged in a staggered pattern. By arranging the recesses 61 in this way, it is possible to effectively prevent the occurrence of inconvenience such as moire. On the other hand, for example, if the concave portions are arranged in a square lattice shape or the like, it is difficult to sufficiently prevent the occurrence of inconvenience such as moire. Further, when the concave portions are randomly arranged, it becomes difficult to sufficiently increase the occupancy ratio of the concave portions in the effective region where the concave portions are formed, and the light transmittance (light utilization efficiency) of the lens substrate is sufficiently increased. Is difficult, and the resulting image is dark.

  In addition, as described above, the recesses 61 are arranged in a staggered pattern when the microlens forming mold 6 is viewed in plan view. It is preferable that the adjacent second row is shifted by a half pitch in the vertical direction. As a result, it is possible to more effectively prevent the occurrence of moire due to light interference and to make the viewing angle characteristics particularly excellent.

  In the above description, it has been described that the concave portion 61 has substantially the same shape (dimension) and arrangement method as the microlens 11 constituting the lens substrate 1. If the constituent material of the lens substrate 1 is easy to shrink (when the resin material (composition 3) constituting the lens substrate 1 shrinks due to solidification or the like), the microlens constituting the lens substrate 1 in consideration of the shrinkage rate, etc. 11 and the concave portion 61 constituting the microlens forming mold 6 may be different in shape (size), occupation ratio, and the like.

Next, a method for manufacturing a microlens forming mold will be described with reference to FIG. In practice, a large number of microlens forming recesses are formed on the substrate. Here, in order to make the explanation easy to understand, a part thereof is highlighted.
First, the substrate 7 is prepared when the microlens forming mold 6 is manufactured.
The substrate 7 having a uniform thickness and having no deflection or scratches is preferably used. The substrate 7 is preferably one whose surface is cleaned by washing or the like.

<A1> A mask 8 having a large number of initial holes (openings) 81 is formed on the surface of the prepared substrate 7, and the back surface of the substrate 7 (the surface opposite to the surface on which the mask 8 is formed) A protective film 89 is formed (see a masking step, FIGS. 4A and 4B).
In particular, in this embodiment, first, as shown in FIG. 4A, the back surface protective film 89 is formed on the back surface of the prepared substrate 7 and the mask forming film 4 is formed on the surface of the substrate 7 (mask). Then, as shown in FIG. 4B, an initial hole 81 is formed in the mask forming film 4 (initial hole forming step) to obtain a mask 8. The mask forming film 4 and the back surface protective film 89 can be formed simultaneously.

The mask forming film 4 is preferably capable of forming an initial hole 81 to be described later by laser light irradiation or the like and having resistance to etching in an etching process to be described later. In other words, the mask formation film 4 (mask 8) is preferably configured so that the etching rate is substantially equal to or lower than that of the substrate 7.
From this point of view, as a material constituting the mask forming film 4 (mask 8), for example, a metal such as Cr, Au, Ni, Ti, Pt, an alloy containing two or more selected from these, Examples thereof include oxides (metal oxides), silicon, and resins.
In addition, the mask forming film 4 (mask 8) may have, for example, a substantially uniform composition, or a laminated body having a plurality of different layers.

  As described above, the configuration of the mask forming film 4 (mask 8) is not particularly limited, but is a laminate having a layer mainly composed of chromium and a layer mainly composed of chromium oxide. Preferably there is. The mask forming film 4 having such a configuration can easily and reliably form an opening having a desired shape by irradiation with laser light as described later. The mask 8 obtained by using the mask forming film 4 has excellent stability with respect to etching solutions having various compositions (the substrate 7 can be more reliably protected in an etching process described later). . Further, when the mask forming film 4 (mask 8) has the above-described configuration, for example, in an etching process described later, a liquid containing ammonium monohydrogen difluoride is preferably used as an etchant. it can. Since ammonium monohydrogen difluoride is not a poisonous deleterious substance, it is possible to prevent the human body and the environment during work more reliably. Further, the mask forming film 4 (mask 8) having the above-described configuration can relieve the internal stress of the mask efficiently, and is particularly excellent in adhesion with the substrate 7 (particularly, adhesion in the etching process). ing. For this reason, by using the mask forming film 4 (mask 8) having the above-described configuration, the concave portion 61 having a desired shape can be easily and reliably formed.

  The method for forming the mask forming film 4 is not particularly limited, but the mask forming film 4 (mask 8) is made of a metal material (including an alloy) such as chromium (Cr) or gold (Au) or a metal oxide (for example, chromium oxide). ), The mask forming film 4 can be suitably formed by, for example, vapor deposition or sputtering. When the mask forming film 4 (mask 8) is made of silicon, the mask forming film 4 can be suitably formed by, for example, a sputtering method or a CVD method.

  The thickness of the mask forming film 4 (mask 8) varies depending on the material constituting the mask forming film 4 (mask 8), but is preferably about 0.001 to 2.0 μm, preferably 0.003 to 0.2 μm. The degree is more preferable. If the thickness is less than the lower limit, the shape of the initial hole 81 formed in the initial hole forming step (opening forming step) described later may be distorted depending on the constituent material of the mask forming film 4 and the like. There is. In addition, when wet etching is performed in an etching process described later, the masked portion of the substrate 7 may not be sufficiently protected. On the other hand, if the upper limit value is exceeded, depending on the constituent material of the mask forming film 4 and the like, it becomes difficult to form the initial hole 81 that penetrates in the initial hole forming step described later, and the mask forming film 4 (mask Due to the internal stress of 8), the mask forming film 4 (mask 8) may be easily peeled off.

  The back surface protective film 89 is for protecting the back surface of the substrate 7 in the subsequent steps. By this back surface protective film 89, erosion, deterioration, etc. of the back surface of the substrate 7 are preferably prevented. The back surface protective film 89 has the same configuration as the mask forming film 4 (mask 8), for example. Therefore, the back surface protective film 89 can be provided in the same manner as the mask forming film 4 simultaneously with the formation of the mask forming film 4.

Next, as shown in FIG. 4B, a plurality of initial holes (openings) 81 are formed in the mask forming film 4 to obtain a mask 8 (initial hole forming step). The initial hole 81 formed in this step functions as a mask opening in the later-described etching.
A method for forming the initial hole 81 is not particularly limited, but a method using laser light irradiation is preferable. Thereby, the initial holes 81 having a desired shape arranged in a desired pattern can be easily and accurately formed. As a result, the shape, arrangement method, and the like of the recesses 61 can be controlled more reliably. In addition, by forming the initial hole 81 by laser irradiation, the microlens forming mold can be manufactured with high productivity. In particular, the concave portion can be easily formed even on a large-area substrate. Further, when forming the initial hole 81 by laser light irradiation, by controlling the irradiation condition, only the initial hole 81 can be formed without forming the initial recess 71 as described later, The initial recess 71 with small variations in shape, size, and depth can be easily and reliably formed. Further, by forming the initial hole 81 in the mask forming film 4 by laser light irradiation, the opening (e.g., easier and less expensive than the case where the opening is formed in the resist film by a conventional photolithography method. An initial hole 81) can be formed.

In addition, when the initial hole 81 is formed by laser light irradiation, the type of laser light to be used is not particularly limited, but a ruby laser, a semiconductor laser, a YAG laser, a femtosecond laser, a glass laser, a YVO ₄ laser, a Ne- He laser, Ar laser, CO ₂ laser, excimer laser or the like may be mentioned. Moreover, you may use wavelengths, such as SHG of each laser, THG, and FHG.

  When the initial hole 81 is formed in the mask forming film 4, not only the mask forming film 4 but also a part of the surface of the substrate 7 is removed at the same time, as shown in FIG. May be. Thereby, when etching is performed in an etching process described later, the contact area with the etching solution is increased, and erosion can be suitably started. Further, by adjusting the depth of the initial recess 71, the depth of the recess 61 (maximum lens thickness) can be adjusted. Although the depth of the initial recessed part 71 is not specifically limited, It is preferable to set it as 5 micrometers or less, and it is more preferable to set it as about 0.1-0.5 micrometer. When the initial hole 81 is formed by laser irradiation, the variation in depth can be more reliably reduced with respect to the plurality of initial concave portions 71 formed together with the initial hole 81. Thereby, the variation in the depth of each recess 61 constituting the microlens forming mold 6 is reduced, and the variation in the size and shape of each microlens 11 of the lens substrate 1 finally obtained is also reduced. As a result, variations in the diameter, focal length, and lens thickness of each microlens 11 can be particularly reduced.

  The shape and size of the initial hole 81 formed in this step is not particularly limited, but it is substantially circular and the diameter is preferably 0.8 to 20 μm, more preferably 1.0 to 10 μm. Preferably, it is 1.5-4 micrometers. When the diameter of the initial hole 81 is a value within the above range, the concave portion 61 having the above-described shape can be reliably formed in the etching process described later. However, when the initial hole 81 has a flat shape such as a substantially elliptical shape, the length in the minor axis direction can be substituted for the value of the diameter. That is, when the initial hole 81 formed in this step has a flat shape, the width of the initial hole 81 (length in the minor axis direction) is not particularly limited, but is preferably 0.8 to 20 μm, More preferably, it is 1.0-10 micrometers, and it is still more preferable that it is 1.5-4 micrometers. When the width of the initial hole 81 is a value within the above range, the concave portion 61 having the above-described shape can be reliably formed in the etching process described later.

In addition, when the initial hole 81 formed in this step is a flat shape, the length of the initial hole 81 (length in the major axis direction) is preferably 0.9 to 30 μm, and preferably 1.5 to More preferably, it is 15 micrometers, and it is still more preferable that it is 2.0-6 micrometers. When the length of the initial hole 81 is a value within the above range, the concave portion 61 having the above-described shape can be more reliably formed in the etching process described later.
In addition to forming the initial hole 81 by irradiating the mask forming film 4 with laser light, for example, when forming the mask forming film 4 on the substrate 7, the foreign material is previously formed in a predetermined pattern on the substrate 7. Then, a defect may be positively formed in the mask forming film 4 by forming the mask forming film 4 thereon, and the defect may be used as the initial hole 81.

<A2> Next, as shown in FIG. 4C, the substrate 7 is etched using the mask 8 in which the initial holes 81 are formed, and a large number of recesses 61 are formed on the substrate 7 (etching step). .
The etching method is not particularly limited, and examples thereof include wet etching and dry etching. In the following description, a case where wet etching is used will be described as an example.

  By performing etching (wet etching) on the substrate 7 covered with the mask 8 in which the initial holes 81 are formed, the substrate 7 is removed from the portion where the mask 8 does not exist, as shown in FIG. A number of recesses 61 are formed on the substrate 7 by etching. As described above, since the initial holes 81 formed in the mask 8 are arranged in a staggered pattern (in a staggered pattern), the formed recesses 61 are formed in a staggered pattern (in a staggered pattern) on the surface of the substrate 7. It will be arranged.

In this embodiment, when the initial hole 81 is formed in the mask forming film 4 in the step <A1> (when the mask 8 is formed), the initial recess 71 is formed on the surface of the substrate 7. Thereby, at the time of etching, the contact area with the etching solution is increased, and erosion can be suitably started.
Further, when the wet etching method is used, the concave portion 61 can be suitably formed. If, for example, an etching solution containing ammonium monohydrogen difluoride is used as the etching solution, the substrate 7 can be etched more selectively, and the recess 61 can be suitably formed.

When the mask 8 (mask forming film 4) is mainly composed of chromium, the hydrofluoric acid-based etchant is particularly preferably a liquid containing ammonium monohydrogen difluoride. Since the ammonium hydrogen difluoride solution is not a poisonous and deleterious substance, it can prevent the influence on the human body and the environment during work. Moreover, when using ammonium monohydrogen difluoride as an etchant, the etchant may contain, for example, hydrogen peroxide. Thereby, an etching speed can be made faster.
Further, according to wet etching, it is possible to perform processing with a simpler apparatus than dry etching, and it is possible to perform processing on many substrates at once. Thereby, productivity is improved and the microlens forming mold 6 can be provided at a low cost.

<A3> Next, as shown in FIG. 4D, the mask 8 is removed (mask removal step). At this time, the back surface protective film 89 is also removed together with the removal of the mask 8, whereby the microlens forming mold 6 is obtained.
When the mask 8 is a laminated body having a layer mainly composed of chromium and a layer mainly composed of chromium oxide as described above, the removal of the mask 8 is, for example, ceric ammonium nitrate and perchlorine. The etching can be performed using a mixture containing an acid.

Further, for example, a mold release process may be performed on the surface side of the microlens forming mold 6 on which the concave portion 61 is provided. Thereby, in the manufacturing method of the lens substrate 1 described in detail later, it is possible to easily remove the microlens forming mold 6 while sufficiently preventing the microlens 11 included in the lens substrate 1 from causing defects such as chipping. it can. Examples of the mold release treatment include formation of a film composed of a material having releasability such as silicone resin such as alkylpolysiloxane, fluorine resin such as polytetrafluoroethylene, and hexamethyldisilazane ([(CH ₃ ) Surface treatment with a silylating agent such as ₃ Si] ₂ NH), surface treatment with a fluorine-based gas, and the like.
As described above, as shown in FIGS. 4D and 3, the microlens forming mold 6 in which a large number of recesses 61 are formed in a staggered pattern on the substrate 7 is obtained.

The method for forming the plurality of recesses 61 arranged in a staggered pattern on the substrate 7 is not particularly limited, but the method as described above (by forming the initial holes 81 in the mask forming film 4 by laser irradiation). When the mask 8 is obtained and then etched using the mask 8 to form the recess 61 on the substrate 7, the following effects are obtained.
That is, by forming the initial hole 81 in the mask forming film 4 by laser light irradiation, the opening (with a predetermined pattern) can be easily and inexpensively compared with the case where the opening is formed by a conventional photolithography method. A mask having initial holes 81) can be obtained. Thereby, productivity is improved and the microlens forming mold 6 can be provided at a low cost.

Further, according to the method as described above, it is possible to easily perform processing on a large substrate. In the case of manufacturing a large substrate, it is not necessary to bond a plurality of substrates as in the prior art, and the seam of bonding can be eliminated. Thereby, a high-quality and large-sized microlens forming mold (lens substrate) can be manufactured at a low cost by a simple method.
Further, when the initial holes 81 are formed by laser irradiation, the shape, size, arrangement, and the like of the formed initial holes 81 can be managed easily and reliably.

Next, a method for manufacturing the lens substrate 1 using the microlens forming mold 6 described above will be described.
5 and 6 are schematic longitudinal sectional views showing an example of a manufacturing method of the lens substrate shown in FIG. In the following description, the lower side in FIGS. 5 and 6 is referred to as “(light) incident side” and the upper side is referred to as “(light) emission side”.

<B1> First, as shown in FIG. 5 (a), the composition 3 (unpolymerized (uncured)) having fluidity is formed on the surface of the microlens forming mold 6 on which the concave portion 61 is formed. Composition 3) is applied. This composition 3 is usually composed mainly of a material that can be cured by energy rays, which will be described in detail later.
In this step, the composition 3 containing the spacer 19 may be used. Thereby, when the composition 3 on the microlens forming mold 6 is pressed by the base material 15 in a process described later, it is possible to prevent unintentional variation in the thickness of the layer composed of the composition 3. Therefore, the focal position of the microlens 11 on the lens substrate 1 finally obtained can be more reliably controlled, and the occurrence of inconvenience such as color unevenness can be more effectively prevented.

When the spacer 19 is used as in the present embodiment, the shape of the spacer 19 is not particularly limited, but is preferably substantially spherical or substantially cylindrical. When the spacer 19 has such a shape, the diameter is preferably 10 to 300 μm, more preferably 30 to 200 μm, and still more preferably 30 to 170 μm.
Prior to application of the composition 3, a release agent may be applied to the surface of the microlens forming mold 6 on the side where the recess 61 is formed. Thereby, in the process to be described later, the lens substrate 1 (more precisely, the substrate 2 as a production intermediate of the lens substrate 1) can be easily separated (peeled) from the microlens forming mold 6. .

  <B2> Next, as shown in FIG.5 (b), the base material 15 is installed on the composition 3, The composition 3 is provided on this base material 15, Furthermore, the composition 3 (base material) A Fresnel lens forming mold (second mold) 9 having a surface shape corresponding to the Fresnel lens 12 is placed on the surface of the composition 3) supplied on the surface 15. And the composition 3 is pressed with the type | mold 9 for Fresnel lens formation installed on the composition 3 (composition pressing process). Thereby, the composition 3 can be reliably adhered to the base material 15, the microlens forming mold 6, and the Fresnel lens forming mold 9. As a result, in the process (energy ray irradiation process) to be described later, the base material 15 and the cured part 16 composed of the cured product of the composition 3 can be reliably bonded, and the adhesion is particularly excellent. In addition, the cured portion 16 to which the surface shapes of the microlens forming mold 6 and the Fresnel lens forming mold 9 are faithfully transferred can be reliably formed.

The base material 15 is usually made of the above-described material (the material of the lens substrate 1). Moreover, as the base material 15, a material having a uniform thickness and having no deflection or scratch is preferably used. The base material 15 is preferably one whose surface is cleaned by washing or the like. Moreover, even if the base material 15 has flexibility, it may be the thing which does not have the difference which ties flexibility substantially.
Although the thickness of the base material 15 is not specifically limited, It is preferable that it is 0.05-5 mm, It is more preferable that it is 0.07-4 mm, It is further more preferable that it is 0.1-3 mm.

  Further, in the composition pressing step, for example, the pressing means may be used to press almost the entire surface of the Fresnel lens forming mold 9 (the entire surface on the side opposite to the contact with the composition 3). . Thereby, the pressure applied to the composition 3 can be made more uniform, and as a result, in the lens substrate 1 that is finally obtained, it is more effective that unintentional variations in thickness occur. Can be prevented. Further, by using the pressing means, the composition 3 can be pressed by the base material 15 and the Fresnel lens forming mold 9 easily and reliably with a relatively large pressure. As a result, the thickness of the lens substrate 1 can be made thinner. As a result, the focal length of the lens can be shortened in designing the lens substrate 1, which is advantageous from the viewpoint of optical characteristics. Further, it is advantageous in reducing the thickness of a device (such as a rear projector) including a lens substrate.

  Any means may be used as the pressing means as described above, but it is preferable to use one made of a metal material such as stainless steel or Ni alloy. Since such a material has high hardness and excellent shape stability, the base material 15 can be suitably pressed at a desired pressure (particularly, a relatively high pressure). Moreover, the above materials are generally excellent in energy beam reflection efficiency as described later. For this reason, when the pressing means is made of the above-described material, the energy of the energy beam is more efficiently used for curing the composition 3 in a step (energy beam irradiation step) described in detail later. be able to. The pressing means may have, for example, a coating composed of various resin materials (including polyparaxylylene), carbon-based materials such as diamond and diamond-like carbon, etc. in the vicinity of the surface. .

  The mold 9 for forming the Fresnel lens may be made of any material, for example, may be made of a material as exemplified as the constituent material of the pressing means described above, or a microlens It may be made of a material as exemplified as a constituent material of the forming mold 6. When the Fresnel lens forming mold 9 is made of the material exemplified as the constituent material of the pressing means described above, the composition 3 and the base material 15 are suitable at a desired pressure (particularly, a relatively high pressure). Can be pressed. Moreover, since the above materials are generally excellent in energy beam reflection efficiency as described later, the energy beam energy is more efficiently used for curing the composition 3 in the energy beam irradiation step. be able to. When the Fresnel lens forming die 9 is made of the material exemplified as the constituent material of the microlens forming die 6 described above, for example, in the energy ray irradiation process, from the Fresnel lens forming die 9 side, Energy rays can be suitably irradiated. In other words, the Fresnel lens forming mold 9 can be used as the first mold, and the microlens forming mold 6 can be used as the second substrate.

In addition, the mold release process may be performed to the surface side which contacts the composition 3 of the mold 9 for forming a Fresnel lens. Thereby, in manufacturing the lens substrate 1, the Fresnel lens forming mold 9 can be easily removed while sufficiently preventing defects such as chipping from occurring in the formed Fresnel lens 12.
In this step, a spacer similar to that described above may be disposed between the base material 15 and the Fresnel lens forming mold 9.

  <B3> Next, as shown in FIG. 5C, the composition 3 is irradiated with energy rays (indicated by E in the drawing) through the microlens forming mold 6. In other words, the composition 3 is irradiated with energy rays from the side in contact with the microlens forming mold 6 as a mold. Thereby, the composition 3 hardens | cures, the hardening part 16 is formed, and the board | substrate 2 (The same member as the lens board | substrate 1 except not having the coloring part 13) is obtained (refer FIG.5 (d)). . Thus, by irradiating the composition 3 with energy rays through the microlens forming mold 6, the composition 3 is suitably pressed by the Fresnel lens forming mold (second substrate) 9 ( For example, energy beam irradiation can be performed in a state where the Fresnel lens forming mold 9 is pressed by the pressing means as described above and the composition 3 is pressed by the Fresnel lens forming mold 9. As a result, in the lens substrate 1 finally obtained, it is possible to more effectively prevent air bubbles from entering between the base material 15 and the cured portion 16 and unintentional variations in thickness. it can. As a result, the lens substrate finally obtained can have high reliability and excellent optical characteristics.

  Further, by irradiating the composition 3 with energy rays from the surface side that contacts the microlens forming mold 6 as the first mold, the surface of the substrate 15 opposite to the surface that contacts the composition 3 is opposite. A state in which the composition 3 is pressed on the surface side by a Fresnel lens forming mold 9 as a second mold made of a material (metal material) having a high reflectivity of energy rays as described above (or energy rays The energy rays can be irradiated in a state where the composition 3 is pressed through the Fresnel lens forming mold 9 by a pressing means made of a material (metal material) having a high reflectance. Thereby, the utilization efficiency of energy rays can be made particularly excellent. That is, the energy rays irradiated from the microlens forming mold 6 side are absorbed by the composition 3 and used for curing the composition 3, but a part of the irradiated energy rays is usually the composition 3. It is transmitted without being used for curing. However, by using the Fresnel lens forming mold 9 (or pressing means) made of the material as described above, the energy rays that have passed through the composition 3 can be reflected, and this reflected The composition 3 can be irradiated again with energy rays. As a result, there is a high possibility that the energy rays give activation energy necessary for the curing reaction to the composition 3, and therefore the curing reaction of the composition 3 can proceed more efficiently.

  The composition 3 may include a diffusing material having a function of diffusing incident energy rays. Thereby, the composition 3 can be hardened efficiently. As the diffusing material, for example, polystyrene beads, glass beads, organic cross-linked polymers and the like can be used. When the diffusing material is made of the material as described above, the viewing angle characteristics of the lens substrate 1 can be made particularly excellent. Here, the diffusing material may be included in the entire composition 3 or may be included in only a part thereof. Although the amount of the diffusing material is not particularly limited, Haze (cloudiness: Td / Tt, Td: diffused light transmittance, Tt: total light transmittance) from the viewpoint of achieving both viewing angle characteristics and light utilization efficiency. ) Is, for example, preferably 30 to 99%.

Examples of energy rays used in this step include ultraviolet rays and electron beams. Among these, ultraviolet rays are preferable. When ultraviolet rays are used as energy rays, for example, the lens substrate 1 can be more easily manufactured with simple equipment. In addition, the degree of freedom in selecting the composition 3 can be increased, and the occurrence of adverse effects on members such as an apparatus used when manufacturing the lens substrate 1 can be more effectively prevented. Further, heating may be performed upon irradiation with energy rays. Thereby, hardening of the composition 3 can be accelerated | stimulated.
Although the thickness of the hardening part 16 formed at this process is not specifically limited, It is preferable that it is 40-80 micrometers. Thus, in this invention, a hardening part can be suitably formed as that whose thickness is small enough.

  <B4> Next, as shown in FIG. 6E, the microlens forming die 6 is removed from the substrate 2 (die removing step). Thus, by removing the microlens forming mold 6 from the substrate 2, the removed microlens forming mold 6 can be repeatedly used for manufacturing the substrate 2 (lens substrate 1). This is advantageous in improving the quality stability of the manufactured substrate 2 (lens substrate 1).

<B5> Thereafter, as shown in FIG. 6 (f), the colored portion 13 is formed by applying a coloring liquid to the substrate 2 removed from the microlens forming mold 6, and the other portions are formed. Let it be the non-colored part 14 (colored part formation process). Thereby, the lens substrate 1 having the colored portion 13 is obtained.
The color liquid may be any, but in the present embodiment, it contains a colorant and benzyl alcohol. By using such a coloring liquid, the substrate 2 can be easily and reliably colored. In particular, it is possible to easily and surely color a substrate made of a material that is difficult to be colored by a conventional coloring method, such as an acrylic resin. This is considered to be due to the following reasons.

  That is, by using a colored liquid containing benzyl alcohol, the benzyl alcohol in the colored liquid penetrates deeply into the substrate and diffuses, loosening the bonds (intermolecular bonds) that make up the substrate, and the colorant enters. Of space. Then, when the colorant easily penetrates deeply into the space secured by benzyl alcohol, the colorant is held in the space (which can be compared to a seat for colorant (colored seat)), and the substrate is colored. And does not easily desorb.

In addition, by using the coloring liquid as described above, a colored portion having a uniform density can be easily and reliably formed. In particular, the substrate (workpiece) to be colored has a fine structure such as a microlens on its surface (one with a small period of unevenness in the two-dimensional direction), and the region to be colored Even if it has a large area, benzyl alcohol can loosen the bonding of the resin molecules itself, so that a colored portion can be formed at a uniform concentration (without uneven transmittance).
Here, benzyl alcohol has a particularly strong function of securing the above-described colored seats relative to the acrylic resin. For this reason, it becomes possible to incorporate the colorant into the substrate more efficiently.

  As a method for applying the coloring liquid, for example, various coating methods such as doctor blade, spin coating, brush coating, spray coating, electrostatic coating, electrodeposition coating, roll coater, textile printing, etc., and the substrate 2 is immersed in the coloring liquid. Although methods, such as dipping, are mentioned, Especially, dipping (especially dip dyeing) is preferable. Thereby, the colored part 13 (especially the colored part 13 of uniform density) can be formed easily and reliably. In particular, when the coloring liquid is applied by dip dyeing, the substrate 2 to which the coloring liquid is applied is composed of a material that is difficult to be colored by a conventional method such as an acrylic resin. Even so, it can be easily and reliably colored. This is because benzyl alcohol and dyes that can be used for dip dyeing are sufficiently present in the solution, so that benzyl alcohol ensures a sufficiently colored seat, facilitating coloring, and even in a large area. Because it can be done.

The step of applying the coloring liquid is preferably performed in a state where the coloring liquid and / or the substrate 2 is set to 60 to 100 ° C. Thereby, even in a large area, the securing of the colored seat of benzyl alcohol can be promoted uniformly, the coloring speed can be increased, and the colored portion 13 can be formed efficiently.
Moreover, you may perform the process of providing a coloring liquid in the state (pressurized state) which raised atmospheric pressure, for example. Thereby, the penetration | invasion of the coloring liquid to the inside of a board | substrate can be accelerated | stimulated, As a result, the colored part 13 can be formed efficiently in a short time.

The application of the coloring liquid may be repeated a plurality of times as necessary (for example, when the concentration of the colored portion 13 to be formed is to be increased).
Further, after the coloring liquid is applied, a heat treatment such as heating or cooling, light irradiation, pressurization of the atmosphere, or decompression may be performed as necessary. Thereby, fixing (stabilization) of the colored portion 13 can be promoted.

Hereinafter, the coloring liquid used in this step will be described in more detail.
Although the content rate of the benzyl alcohol in a coloring liquid is not specifically limited, It is preferable that it is 0.01-10.0 wt%, it is more preferable that it is 0.05-8.0 wt%, 0.1-5 More preferably, it is 0.0 wt%. When the content of benzyl alcohol is within the above range, it is easy to effectively prevent the occurrence of adverse effects on the substrate 2 on which the colored portion 13 is to be formed (for example, deterioration of the constituent materials of the substrate 2). And the suitable coloring part 13 can be formed reliably.

  The colorant contained in the coloring liquid may be any dye or pigment, but is preferably a dye, more preferably a disperse dye and / or a cationic dye, and a disperse dye. More preferably. Thereby, it is possible to efficiently form the colored portion while sufficiently preventing an adverse effect on the substrate on which the colored portion is to be formed (for example, deterioration of the constituent materials of the substrate). In particular, even if the substrate 2 to which the coloring liquid is applied is made of a material that is difficult to be colored by a conventional method such as an acrylic resin, it is easily and reliably colored. Can do. This is thought to be because the colorant as described above is more easily colored because the ester group (ester bond) of the acrylic resin or the like is used as a dyeing seat.

  Further, the coloring liquid preferably further contains a surfactant. As a result, the colorant can be stably and uniformly dispersed even in the presence of benzyl alcohol, and the substrate 2 to which the color liquid is applied is colored by a conventional method such as an acrylic resin. Even those made of materials that are difficult to color can be easily and reliably colored. Examples of the surfactant include nonionic (nonionic), anionic surfactant, cationic surfactant, and amphoteric surfactant. Nonionic (nonionic) surfactants include, for example, ether surfactants, ester surfactants, ether ester surfactants, nitrogen-containing surfactants, and more specifically, , Polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, acrylic acid ester, methacrylic acid ester and the like. Examples of the anionic surfactant include various rosins, various carboxylates, various sulfates, various sulfonates, various phosphates, etc. More specifically, gum rosin, polymerized rosin , Heterogenized rosin, maleated rosin, fumarized rosin, maleated rosin pentaester, maleated rosin glycerin ester, tristearate (for example, metal salt such as aluminum salt), distearate (for example, aluminum salt) , Metal salts such as barium salts), stearates (eg, metal salts such as calcium salts, lead salts, zinc salts), linolenate salts (eg, cobalt salts, manganese salts, lead salts, zinc salts, etc.) Metal salts, etc.), octanoates (eg, metal salts such as aluminum salts, calcium salts, cobalt salts, etc.), oleates (examples) For example, calcium salts, metal salts such as cobalt salts, etc.), palmitates (eg, metal salts such as zinc salts), naphthenates (eg, calcium salts, cobalt salts, manganese salts, lead salts, zinc salts, etc.) Metal salts, etc.), resinates (eg, metal salts such as calcium salt, cobalt salt, manganese lead salt, zinc salt etc.), polyacrylates (eg metal salts such as sodium salt, etc.), polymethacrylic acid Salt (for example, metal salt such as sodium salt), polymaleate (for example, metal salt such as sodium salt), acrylic acid-maleic acid copolymer salt (for example, metal salt such as sodium salt), cellulose , Dodecylbenzene sulfonate (eg, sodium salt), alkyl sulfonate, polystyrene sulfonate (eg, metal salt such as sodium salt), alkyl diphenyl ester, etc. Terujisuruhon salts (e.g., metal salts such as sodium salt), and the like. Examples of the cationic surfactant include various ammonium salts such as a primary ammonium salt, a secondary ammonium salt, a tertiary ammonium salt, and a quaternary ammonium salt. More specifically, (mono) Examples thereof include alkylamine salts, dialkylamine salts, trialkylamine salts, tetraalkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolinium salts, and the like. Examples of amphoteric surfactants include various betaines such as carboxybetaine and sulfobetaine, various aminocarboxylic acids, and various phosphate esters.

  <B6> Thereafter, as shown in FIG. 6G, the lens substrate 1 is removed from the Fresnel lens forming mold 9. As described above, by removing the Fresnel lens forming mold 9, the removed Fresnel lens forming mold 9 can be repeatedly used for manufacturing the lens substrate 1, and the manufacturing cost and the lens substrate 1 to be manufactured can be reduced. This is advantageous in improving the stability of quality.

[Second Embodiment]
Next, a second embodiment of the lens substrate and the lens substrate manufacturing method of the present invention will be described. In the following description, differences from the above-described embodiment (first embodiment) will be mainly described, and description of similar matters will be omitted.
FIG. 7 is a schematic longitudinal sectional view showing a second embodiment of the lens substrate of the present invention. In the following description, the left side in FIG. 7 is referred to as “(light) incident side” and the right side is referred to as “(light) emission side”.

As shown in FIG. 7, the lens substrate 1 of the present embodiment has a microlens 11 ′ as a concave lens. Thus, in the present invention, the microlens is not limited to a convex lens but may be a concave lens. The microlens 11 ′ is provided as a concave lens having a concave surface on the light incident surface side, so that the manufacturing cost of the lens substrate 1 is further reduced and a large number of lens substrates 1 are produced. Also, the reliability of these lens substrates 1 can be made particularly high. This is considered to be due to the following reasons. That is, when manufacturing the lens substrate 1 having the microlens 11 ′ as a concave lens, a mold (first mold) having a convex portion corresponding to the microlens 11 ′ can be used. Compared to the microlens forming mold 6, a microprojection having a small number of projections (having a gentle convex portion) can be used. For this reason, when manufacturing the lens substrate 1, it can prevent more effectively that defects, such as a crack and a chip, arise in the fine projection part which a type | mold (1st type | mold) has. Therefore, the manufactured lens substrate 1 has a highly accurate microlens 11 ′, and even when a large number of lens substrates 1 are manufactured, the variation in characteristics among these lens substrates 1 is small and more reliable. It can be made highly.
In particular, in this embodiment, the microlens 11 ′ as a concave lens is provided on the light incident side, and the Fresnel lens 12 is provided on the light emission side. With such a configuration, in particular, the front luminance (luminance when observed from the direction perpendicular to the surface direction of the lens substrate 1) can be made higher.

  The lens substrate 1 of the present embodiment as described above has a surface shape corresponding to the surface shape of the lens substrate 1 on which the microlenses 11 ′ are provided as a microlens forming mold (first mold). In addition, the same as described in the first embodiment, except that one having a plurality of recesses (microlens forming recesses) arranged in a manner corresponding to the arrangement method of the microlenses 11 ′ is used. Can be manufactured. In such a microlens forming mold (first mold), for example, a material having fluidity is applied to the surface of the microlens forming mold 6 described in the first embodiment, and then the material is solidified ( It can be suitably manufactured by being cured. In such a method, the application and solidification of the material having fluidity can be performed by the same method and conditions as the application and solidification of the composition described in the first embodiment.

[Rear type projector]
A rear projector provided with the lens substrate (transmission screen) will be described below.
FIG. 8 is a diagram schematically showing the configuration of the rear projector of the present invention.
As shown in the figure, the rear projector 300 has a configuration in which a projection optical unit 310, a light guide mirror 320, and a lens substrate 1 (lens substrate 1 as a transmissive screen) are arranged in a housing 340. is doing.

Since the rear projector 300 includes the lens substrate 1 (the lens substrate 1 as a transmission screen) as described above, a highly reliable image can be obtained. Furthermore, since the present embodiment has the above-described configuration, the viewing angle characteristics, light utilization efficiency, and the like are particularly excellent.
In particular, in the lens substrate 1 described above, since the elliptical microlenses 11 are arranged in a staggered pattern (in a staggered pattern), the rear projector 300 is not particularly susceptible to problems such as moire.

  In the above description, the lens substrate is described so that the surface on which the microlens is formed is disposed on the light incident side. However, the lens substrate may be installed in the opposite direction. Good. That is, the lens substrate may be installed so that the Fresnel lens is disposed on the light incident side and the microlens is disposed on the light exit side. Thereby, for example, the following effects can be obtained. That is, by using a lens substrate 1 (lens substrate 1 having a microlens 11 as a convex lens) as shown in FIG. 1 so that the microlens 11 is arranged on the light emission side, the light use efficiency is increased. Can be made particularly excellent. This is considered to be because the component of the incident light that is disposed at the step portion of the Fresnel lens 12 can be efficiently used as light for image formation. Further, the lens substrate 1 (lens substrate 1 provided with a microlens 11 ′ as a concave lens) as shown in FIG. 7 is installed so that the microlens 11 ′ is arranged on the light emission side. Similarly, light loss at the Fresnel lens 12 can be effectively prevented, and the light utilization efficiency can be made particularly excellent.

As mentioned above, although this invention was demonstrated based on embodiment of illustration, this invention is not limited to these.
For example, each part of the lens substrate and the rear type projector can be replaced with an arbitrary structure that can exhibit the same function.
Further, in the above-described embodiment, the energy beam curing treatment is performed in a state where the base material is disposed between the composition on the microlens forming mold side and the composition on the Fresnel lens forming mold side, Although it demonstrated as what obtains the lens board | substrate which has a hardening part on the both surfaces side of this, a base material does not necessarily need to be used.

In the above-described embodiment, the composition is applied to the surface of the microlens forming mold. For example, a resin is applied to the surface of the Fresnel lens forming mold (second mold), The lens substrate may be manufactured by pressing with a microlens forming mold (first mold).
In the above-described embodiment, the composition supplied onto the microlens forming mold (first mold) is pressed and then irradiated with energy rays. However, the composition is pressed. It does not have to be. For example, in a state where the first mold (microlens forming mold) and the second mold (Fresnel lens forming mold) are held so as to be separated from each other by a predetermined distance, the composition is supplied to the gap between them ( Filling) and then irradiation with energy rays may be performed.

In the above-described embodiment, the coloring portion is described as being formed by applying a coloring liquid containing a coloring agent to the side of the substrate that is in contact with the microlens forming mold. However, the coloring portion is formed. The method is not limited to such a method. For example, the colored portion may be formed by using a composition composed of a material containing a colorant as the composition supplied to the microlens forming mold side. Accordingly, the cured part on the microlens side can be made of a material containing a colorant, and the cured part on the base material and the Fresnel lens side can be made of a material substantially free of a colorant. .
In the above-described embodiment, the colored portion is described as being formed on a part of the cured portion, but may be formed on at least a portion of the base material. Moreover, there may not be a coloring part. In other words, for example, the substrate 2 as described above may be used as the lens substrate.

In the above-described embodiment, the initial hole forming step of the microlens forming mold manufacturing method has been described as forming the initial recess 71 in the substrate 7 together with the initial hole 81. It does not have to be formed. By appropriately adjusting the conditions for forming the initial hole 81 (for example, the laser energy intensity, the beam diameter, the irradiation time, etc.), the initial recess 71 having a desired shape is formed or the initial hole 71 is not formed. Only 81 can be selectively formed.
In the above-described embodiment, the microlens forming mold is not necessarily removed in the manufacture of the lens substrate, as the microlens forming mold is removed. In other words, the microlens forming mold may constitute a part of the lens substrate.

  Further, in the above-described embodiment, the lens substrate is described as a member constituting the rear projector, but the use of the lens substrate of the present invention is not limited to the above, and is any type. May be. For example, the lens substrate of the present invention may be applied to a diffusion plate, a constituent member of a liquid crystal light valve of a projection display device (front projector), or the like.

[Production of lens substrate (transmission type screen)]
Example 1
A microlens forming mold (first mold) having a microlens forming recess was manufactured as follows.
First, a soda glass substrate (absolute refractive index n ₂ : 1.50) having a width of 1.2 m × length of 0.7 m square and a thickness of 4.8 mm was prepared as a substrate.
This soda glass substrate was immersed in a cleaning solution containing 4 wt% ammonium monohydrogen difluoride and 8 wt% hydrogen peroxide and etched by 6 μm to clean the surface.
Thereafter, cleaning with pure water and drying using N ₂ gas (removal of pure water) were performed.

  Next, a chromium / chromium oxide laminate (a laminate in which chromium oxide was laminated on the outer surface side of chromium) was formed on the soda glass substrate by sputtering. That is, a mask forming film and a back surface protective film made of a chromium / chromium oxide laminate were formed on the surface of a soda glass substrate. The thickness of the chromium layer was 0.03 μm, and the thickness of the chromium oxide layer was 0.01 μm.

Next, laser processing was performed on the mask forming film to form a large number of initial holes in a range of 113 cm × 65 cm in the central portion of the mask forming film, thereby obtaining a mask.
The laser processing was performed using an excimer laser under conditions of an energy intensity of 1 mW, a beam diameter of 3 μm, and a scanning speed of 0.1 m / second.
Thus, initial holes having a predetermined length were formed in a staggered pattern over the entire range of the mask. The average width of the initial holes was 2 μm, and the average length was 2 μm.
At this time, a concave portion and a modified layer having a depth of 50 mm were also formed on the surface of the soda glass substrate.

Next, wet etching was performed on the soda glass substrate to form concave portions (recesses for forming microlenses) having a flat shape (substantially elliptical shape) when viewed in plan on the soda glass substrate. The formed many recesses had substantially the same shape as each other. The length (pitch) in the minor axis direction of the formed recess was 54 μm, the length in the major axis direction was 72 μm, the radius of curvature was 36 μm, and the depth was 36 μm. Moreover, the occupation rate of the recessed part in the effective area | region in which the recessed part was formed was 100%.
In the wet etching, an aqueous solution containing 4 wt% ammonium monohydrogen difluoride and 8 wt% hydrogen peroxide was used as an etchant, and the immersion time was 2.0 hours.

Next, the mask and the back surface protective film were removed by etching using a mixture of ceric ammonium nitrate and perchloric acid.
Next, cleaning with pure water and drying (removing pure water) using N ₂ gas were performed.
Thereafter, a gas phase surface treatment (silylation treatment) with hexamethyldisilazane was performed on the surface side of the substrate where the concave portions were formed, thereby forming a release treatment portion.
As a result, a microlens forming mold having a large number of microlens forming recesses arranged in a staggered pattern on a soda glass substrate as shown in FIG. 3 was obtained. When the obtained microlens forming mold was viewed in plan, the ratio of the area occupied by the recesses in the effective region where the recesses were formed was 97%.

Next, an unpolymerized (uncured) acrylic resin (PMMA resin (methacrylic resin)) and a cured (polymerized) acrylic resin (on the surface where the concave portion of the microlens forming mold is formed) A composition composed of a mixture with a spacer (diameter: 10 μm) composed of PMMA resin (methacrylic resin) was applied.
Next, a substrate (flat plate member) made of a cured (polymerized) acrylic resin (PMMA resin (methacrylic resin)) was placed on the surface of the composition on the microlens forming mold. The thickness of the base material was 0.1 mm.
Thereafter, a composition composed of an unpolymerized (uncured) acrylic resin (PMMA resin (methacrylic resin)) was applied on the substrate.

Next, the surface of the composition applied on the substrate is made of a cured (polymerized) acrylic resin (PMMA resin (methacrylic resin)) and has a surface shape corresponding to the Fresnel lens. A Fresnel lens forming mold (second mold) was installed.
Thereafter, the Fresnel lens forming mold was pressed by a pressing means, and the composition and the substrate were pressed by the Fresnel lens forming mold. As the pressing means, a pressing portion that presses the substrate was flat and made of stainless steel.
Then, the composition was cured by irradiating the composition with ultraviolet rays as energy rays from the side of the microlens forming mold while pressing with the pressing means. Thereby, the board | substrate with which the hardening part formed when the composition hardened | cured was joined to the both surfaces side of the base material was obtained.

Next, the microlens forming mold was removed from the obtained substrate.
Thereafter, a colored portion was formed by applying a colored liquid at 80 ° C. to the surface side of the substrate on which the microlens was formed, which was removed from the microlens forming mold. As the coloring liquid, a liquid containing a coloring agent (dye Blue (manufactured by Futaba Sangyo), Red (manufactured by Futaba Sangyo) and Yellow (manufactured by Futaba Sangyo)), benzyl alcohol, and a surfactant was used. The content of benzyl alcohol in the coloring liquid was 2.0 wt%.
Thereafter, the Fresnel lens forming mold was removed to obtain a lens substrate (lens substrate functioning as a transmission screen) as shown in FIG.

(Examples 2 to 5)
Except for adjusting the formation conditions and etching conditions of the initial holes in the production of the microlens forming mold, and the constituent materials of the composition used for the production of the lens substrate, the types of energy rays, etc., as shown in Table 1 above. A lens substrate (a lens substrate functioning as a transmission screen) was produced in the same manner as in Example 1.

(Example 6)
A lens substrate (a lens substrate that functions as a transmissive screen) was manufactured in the same manner as in Example 1 except that the microlens forming mold used for manufacturing the lens substrate was changed and the microlens was formed as a concave lens. The lens substrate manufactured in this example was configured as shown in FIG.

The microlens forming substrate was manufactured as follows.
First, the microlens forming mold manufactured in Example 1 was prepared as a mold for manufacturing a first mold (first mold manufacturing mold).
Next, unpolymerized (uncured) acrylic resin (PMMA resin (methacrylic resin)) was applied to the surface on the side where the concave portion of the first mold manufacturing die was formed.

Next, a flat plate member made of an acrylic resin (PMMA resin (methacrylic resin)) whose surface was subjected to a mold release treatment was placed on the surface of the composition on the first mold production mold.
Then, the flat member was pressed by the pressing means, and the uncured acrylic resin was pressed by the flat member. As the pressing means, a pressing portion that presses the substrate was flat and made of stainless steel.

  Thereafter, the acrylic resin was cured by irradiating the uncured acrylic resin with ultraviolet rays as energy rays from the first mold manufacturing mold side while pressing with the pressing means. Thereafter, the first mold manufacturing die and the flat plate member were removed from the obtained cured product. Thereafter, a gas phase surface treatment (silylation treatment) with hexamethyldisilazane is performed on the surface side on which the convex portions of the cured product are formed, thereby forming a release treatment portion, whereby a microlens forming mold ( A first mold) was obtained.

(Comparative Example 1)
As a microlens forming mold, a mold made of copper and having the same shape as that used in Example 1 was prepared.
Next, a substrate (flat plate member) made of a cured (polymerized) acrylic resin (PMMA resin (methacrylic resin)) was placed on the surface of the composition on the microlens forming mold. The thickness of the base material was 0.1 mm. Then, the base material was pressed with the pressing means, and the composition was pressed with the base material. As the pressing means, a pressing portion that presses the substrate was flat and made of stainless steel.
Thereafter, the pressing by the pressing means was released, and the composition was cured by irradiating the composition with ultraviolet rays as energy rays from the substrate side. Thereby, the board | substrate with which the hardening part formed when the composition hardened | cured joined to a base material was obtained.

Next, the microlens forming mold was removed from the obtained substrate.
Thereafter, a colored part was formed on the surface of the substrate removed from the microlens forming mold on which the microlens was formed, thereby obtaining a microlens substrate having a large number of microlenses on one surface. . The colored portion was formed under the same conditions as in Example 1.
On the other hand, a mold made of copper and having the same shape as that used in Example 1 was prepared as a mold for forming a Fresnel lens.

Next, a base material (flat plate member) made of a cured (polymerized) acrylic resin (PMMA resin (methacrylic resin)) was placed on the surface of the composition on the mold for forming the Fresnel lens. The thickness of the base material was 0.1 mm. Then, the base material was pressed with the pressing means, and the composition was pressed with the base material. As the pressing means, a pressing portion that presses the substrate was flat and made of stainless steel.
Thereafter, the pressing by the pressing means was released, and the composition was cured by irradiating the composition with ultraviolet rays as energy rays from the substrate side. Thereby, the board | substrate with which the hardening part formed when the composition hardened | cured joined to a base material was obtained.

Next, the Fresnel lens substrate was obtained by removing the Fresnel lens forming mold from the obtained substrate.
Thereafter, a transmissive screen was assembled using the microlens substrate and the Fresnel lens substrate obtained as described above. At this time, the microlens substrate was assembled so that the surface side on which the microlens was provided opposed to the Fresnel lens substrate.

(Comparative Example 2)
A substrate was manufactured in the same manner as in Comparative Example 1 except that a substrate having a thickness of 2 mm was used.
Then, the base material which the board | substrate has was grind | polished by grinding | polishing until the thickness became 0.1 mm.
Thereafter, the same process as in Comparative Example 1 was performed to manufacture a microlens substrate.
Thereafter, a transmissive screen was assembled using the microlens substrate obtained as described above and the Fresnel lens substrate manufactured in the same manner as in Comparative Example 1. At this time, the microlens substrate was assembled so that the surface side on which the microlens was provided opposed to the Fresnel lens substrate.

  In each of the above examples, a lens substrate (a lens substrate functioning as a transmission screen) could be easily and reliably manufactured with excellent productivity, whereas in Comparative Examples 1 and 2, the micro lens substrate and The alignment with the Fresnel lens substrate is necessary, and the productivity of the transmission screen was inferior. In particular, in Comparative Example 2, since the substrate was polished in the manufacture of the microlens substrate, the productivity of the microlens substrate and the transmission screen was particularly low.

  Table 1 summarizes the manufacturing conditions of the lens substrate (lens substrate having a microlens), the configuration of the lens substrate (lens substrate having a microlens), and the like for each of the examples and the comparative examples. In the table, the methacrylic resin is indicated by “PMMA”. As for the irradiation direction of the energy beam, irradiation from the microlens forming mold side is indicated as “normal”, and irradiation from the opposite side is indicated as “reverse”.

[Evaluation of light utilization efficiency]
The light use efficiency was evaluated for the lens substrates of the examples and the transmissive screens of the comparative examples.
Evaluation of the light utilization efficiency is measured on the light exit surface side of the lens substrate (the transmission screen in the comparative example) when white light of A (= 300) [cd / m ² ] is incident. The measurement was performed by determining the ratio (B / A) of the luminance B [cd / m ² ] of light. It can be said that the larger the value of B / A, the better the light utilization efficiency. For each example, the light utilization efficiency when light is incident from the surface side where the microlens is provided is obtained, and for each comparative example, the light is incident from the surface side where the Fresnel lens substrate is installed. The utilization efficiency of light was calculated.

[Production of rear projector]
Rear projectors as shown in FIG. 8 were produced using the lens substrates of the respective examples and the transmissive screens of the comparative examples.
In Comparative Examples 1 and 2, the Fresnel lens substrate was installed on the light incident side, and the light (parallel light) transmitted through the Fresnel lens substrate was installed so as to enter the microlens substrate. In Examples 1 to 6, the lens substrate is disposed so that the microlens is disposed on the light incident side, and the lens substrate is disposed so that the microlens is disposed on the light emission side. What was installed was produced. “−a” indicates that the lens substrate is disposed so that the microlens is disposed on the light incident side, and “−b” indicates that the lens substrate is disposed so that the microlens is disposed on the light emission side. It was.

[Bright spots and missing dots]
Sample images (moving images) were displayed on the transmissive screens (lens substrates) of the rear projectors of the examples and comparative examples. The displayed images were evaluated for the occurrence of bright spots and missing dots according to the following four criteria.
A: Bright spots and missing dots are not recognized at all.
○: Bright spots and missing dots are hardly recognized.
Δ: At least one of bright spots and missing dots is slightly recognized.
X: At least one of bright spots and missing dots is noticeable.

[Evaluation of contrast]
Contrast evaluation was performed on the rear projectors of each of the examples and comparative examples.
As contrast (CNT), the front luminance (white luminance) LW [cd / m ² ] of white display when all white light of 413 lx is incident in the dark room, and the front luminance of black display when the light source is completely turned off in the bright room The ratio LW / LB with the increase amount (black luminance increase amount) LB [cd / m ² ] was obtained. The black luminance increase amount is an increase amount with respect to the black display luminance in the dark room. The measurement in the bright room was performed under an environment where the ambient light illuminance was about 185 lx. The measurement in the dark room was performed in an environment where the external light illuminance was 0.1 lx or less.

[Measurement of viewing angle]
With the sample images displayed on the transmission screens (lens substrates) of the rear projectors of the respective Examples and Comparative Examples, the viewing angles in the vertical direction and the horizontal direction were measured.
The viewing angle was measured under the condition of measuring with a variable angle photometer (goniophotometer) at intervals of 1 degree.

[Evaluation of diffracted light, moire and color unevenness]
Sample images were displayed on the transmissive screens (lens substrates) of the rear projectors of the examples and comparative examples. The displayed images were evaluated for the occurrence of diffracted light, moire and color unevenness according to the following four criteria.
A: No diffracted light, moire, or color unevenness is observed.
○: Almost no diffracted light, moire or color unevenness is observed.
Δ: At least one of diffracted light, moire, and color unevenness is slightly observed.
X: At least one of diffracted light, moire and color unevenness is remarkably recognized.
These results are summarized in Table 2.

As can be seen from Table 2, in the present invention, the light use efficiency was excellent, excellent contrast was obtained, and the occurrence of bright spots, missing dots, etc. was effectively prevented. Further, in the present invention, an excellent image having excellent viewing angle characteristics and free from diffracted light, moire, and color unevenness could be displayed. That is, in the present invention, an excellent image can be stably displayed.
On the other hand, in the comparative example, a satisfactory result was not obtained. This is considered to be due to the following reasons. That is, in the comparative example, when the composition is cured by energy rays, the microlens forming mold, the composition, the pressing member, and the like cannot be brought into close contact with each other in a suitable state. Air bubbles enter and remain between molds, between the composition and the pressing member (base material, Fresnel lens forming mold), etc., and the surface of the substrate placed on the surface of the composition does not become flat. This is thought to be due to the occurrence of this problem.

  In the present invention, the light utilization efficiency and the image contrast are particularly excellent as compared with the comparative example, and this is considered to be due to the following reasons. That is, in the present invention, since the microlens and the Fresnel lens are provided on one lens substrate, the reflective interface is compared with a configuration in which two lens substrates are used as in the transmission screen of the comparative example. Can be reduced. Since the light transmittance at the reflection interface is not lowered, it is considered that the light utilization efficiency and the image contrast are particularly excellent in the present invention compared to the comparative example.

It is a typical longitudinal section showing a 1st embodiment of a lens substrate of the present invention. It is a top view from the surface side in which the micro lens of the lens substrate shown in FIG. 1 was provided. It is a typical longitudinal cross-sectional view which shows the microlens formation type | mold (1st type | mold) used for manufacture of a lens board | substrate. It is a typical longitudinal cross-sectional view which shows the manufacturing method of the microlens formation type | mold shown in FIG. It is a typical longitudinal cross-sectional view which shows an example of the manufacturing method of the lens substrate shown in FIG. It is a typical longitudinal cross-sectional view which shows an example of the manufacturing method of the lens substrate shown in FIG. It is a typical longitudinal section showing a 2nd embodiment of a lens substrate of the present invention. It is a figure which shows typically the rear type projector to which the lens board | substrate of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lens substrate 11, 11 '... Micro lens 111 ... Center 12 ... Fresnel lens 13 ... Colored part 14 ... Non-colored part 15 ... Base material (base material for lens substrates) 16 ... Hardening part 17 ... 1st row | line | column 18 ... Second row 19 ... Spacer 2 ... Substrate 3 ... Composition 4 ... Mask formation film 6 ... Microlens formation mold (first mold) 61 ... Recess (microlens formation recess) 7 ... Substrate 71 ... Initial recess DESCRIPTION OF SYMBOLS 8 ... Mask 81 ... Initial hole (opening part) 89 ... Back surface protective film 9 ... Mold for Fresnel lens formation (2nd type) 300 ... Rear type projector 310 ... Projection optical unit 320 ... Light guide mirror 340 ... Case

Claims (13)

A composition supplying step of supplying a fluid composition between the first mold and the second mold;
An energy ray irradiating step for curing the composition by irradiating the composition with an energy ray from the surface side in contact with the first mold;
One of the first mold and the second mold has irregularities corresponding to the surface shape of the microlens, and the other has irregularities corresponding to the surface shape of the Fresnel lens And
A method of manufacturing a lens substrate, wherein the first mold is made of a material having transparency to the energy beam.   The method of manufacturing a lens substrate according to claim 1, wherein the composition supplying step is performed by pressing the composition with the second mold after supplying the composition onto the first mold.   In the composition supplying step, a plate-like or film-like substrate is disposed between the first mold and the second mold, and the composition is disposed on both sides of the substrate. The method for producing a lens substrate according to claim 1 or 2, wherein the method is carried out in a state where   In the composition supply step, after the composition is supplied onto the first mold, a plate-like or film-like substrate is placed on the surface of the composition, and then the composition is formed on the surface of the substrate. The manufacturing method of the lens substrate of Claim 1 or 3 performed by supplying a thing and further pressing the said composition on the said base material with a said 2nd type | mold.   The method of manufacturing a lens substrate according to claim 1, wherein the energy ray is ultraviolet light.   6. The method for manufacturing a lens substrate according to claim 1, further comprising a mold removing step of removing the first mold and the second mold after the energy beam irradiation process.   The method for manufacturing a lens substrate according to claim 1, wherein the first mold is made of a glass material.   The method for manufacturing a lens substrate according to claim 1, wherein the composition is mainly composed of an acrylic resin.   The method of manufacturing a lens substrate according to claim 1, wherein the radius of curvature of the microlens is 5 to 300 μm.   The method for manufacturing a lens substrate according to claim 1, wherein the microlens has a flat shape in which a vertical width when the lens substrate is viewed in plan is smaller than a horizontal width.   The method of manufacturing a lens substrate according to claim 1, wherein the thickness of the lens substrate is 0.5 to 5 mm.   A lens substrate manufactured using the method according to claim 1.   A rear projector, comprising the lens substrate according to claim 12.

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