JP2007010803A - Transmission type screen and rear type projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rear type projector excellent in the characteristic of a visibility angle in each direction and capable of displaying a high-luminance picture, and to provide a transmission type screen suitably applied to the rear type projector. <P>SOLUTION: The transmission type screen is equipped with a micro lens base plate where many micro lenses are formed. The radius of curvature in the vicinity of the periphery part of the micro lens in the vertical direction of the transmission type screen is larger than that in the vicinity of the center thereof. When the radius of curvature in the vicinity of the periphery part of the micro lens in the vertical direction of the transmission type screen is defined as R<SB>0</SB>[μm] and the radius of curvature in the vicinity of the center thereof is defined as R<SB>1</SB>[μm], they satisfy the relation: 1.5≤R<SB>0</SB>/R<SB>1</SB>≤1000. The radius of curvature of the micro lens in the horizontal direction of the transmission type screen is 5 to 250μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmissive screen and a rear projector.

A display device that projects an image on a screen is known. As such a display device, a rear-type projector applied to a home theater monitor, a large-screen television, or the like is known, and the demand thereof has been increasing in recent years.
In such a rear projector, a transmissive screen is mainly used for image formation.

  A wide viewing angle characteristic is particularly required for a transmission screen used in such a rear projector. As such a transmissive screen having a wide viewing angle characteristic, a screen having a Fresnel lens portion on which a Fresnel lens is formed and a lens substrate such as a microlens substrate or a lenticular lens substrate on which a minute lens portion is formed. It is known (see, for example, Patent Document 1).

However, a transmissive screen provided with a lenticular lens substrate is excellent in left and right viewing angle characteristics, but has a problem in that it is inferior in vertical viewing angle characteristics.
On the other hand, a transmissive screen provided with a microlens substrate has an advantage that good viewing angle characteristics can be obtained in both the vertical and horizontal directions, but the brightness of an image projected on the screen is reduced. There was a problem.

JP 2000-131506 A (Claims)

  An object of the present invention is to provide a rear projector capable of displaying a high-luminance image while being excellent in viewing angle characteristics in each direction, and a transmission type that can be suitably applied to the rear projector. To provide a screen.

Such an object is achieved by the present invention described below.
The transmission screen of the present invention is a transmission screen including a microlens substrate on which a large number of microlenses are formed,
In the vertical direction of the transmissive screen, the radius of curvature near the periphery of the microlens is larger than the radius of curvature near the center.
Accordingly, it is possible to provide a transmissive screen that is excellent in viewing angle characteristics in each direction and can be suitably applied to a rear projector that can display a high-luminance image.

In the transmissive screen of the present invention, when the radius of curvature near the periphery of the microlens in the vertical direction of the transmissive screen is R ₀ [μm] and the radius of curvature near the center is R ₁ [μm], It is preferable to satisfy the relationship of 5 ≦ R ₀ / R ₁ ≦ 1000.
Accordingly, it is possible to effectively prevent a decrease in luminance while improving the viewing angle characteristics in each direction.

In the transmissive screen of the present invention, the curvature radius of the microlens in the horizontal direction of the transmissive screen is preferably 5 to 250 μm.
Thereby, the viewing angle characteristic in the horizontal direction can be made excellent.
In the transmissive screen according to the aspect of the invention, it is preferable that the microlens has a flat shape in which the vertical width when the microlens substrate is viewed in plan is smaller than the horizontal width.
This makes it possible to effectively prevent the occurrence of moire due to light interference while improving the viewing angle characteristics in each direction.

In the transmission screen of the present invention, the microlens has a length in the minor axis direction of X [μm] and a length in the major axis direction of Y [μm], and 0.001 ≦ X / Y ≦ 1. It is preferable to satisfy the relationship of 40.
Thereby, the microlens substrate has a more preferable viewing angle distribution.
In the transmission screen of the present invention, it is preferable that the length of the micro lens in the long axis direction is 10 to 500 μm.
Thereby, sufficient resolution can be obtained in the projected image while effectively preventing the occurrence of inconvenience such as moire.
In the transmissive screen of the present invention, it is preferable that the length of the microlens in the minor axis direction is 10 to 400 μm.
Thereby, sufficient resolution can be obtained in the projected image while effectively preventing the occurrence of inconvenience such as moire.

In the transmission screen of the present invention, when the microlens substrate is viewed in plan, the first row composed of a plurality of microlenses and the second row adjacent to the first row are shifted by a half pitch in the horizontal direction. It is preferable.
As a result, the generation of moire due to light interference can be more effectively prevented, and the viewing angle characteristics can be made particularly excellent.

A rear projector according to the present invention includes the transmission screen according to the present invention.
Accordingly, it is possible to provide a rear projector that is excellent in viewing angle characteristics in each direction and can display a high-luminance image.

Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
In the present invention, the “substrate” refers to a concept that is substantially inflexible and includes a relatively large thickness, a sheet-like material, a film-like material, and the like. .
[Microlens substrate]
First, a microlens substrate used in the transmission screen of the present invention will be described.

  FIG. 1 is a plan view showing a preferred embodiment of a microlens substrate used in the transmission screen of the present invention, and FIG. 2 is a vertical sectional view of the microlens substrate shown in FIG. 1 in the vertical direction. In the following description, the left side in FIG. 2 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.

The microlens substrate 1 is a member constituting a transmission screen 10 described later, and includes a plurality of convex microlenses (convex lenses) 21 arranged in a predetermined pattern, as shown in FIGS. A substrate body 2 and a black matrix (light-shielding film) 3 made of a light-shielding material are provided.
The substrate body 2 is usually made of a transparent material.
The constituent material of the substrate body 2 is not particularly limited, but is mainly composed of a resin material and is composed of a transparent material having a predetermined refractive index.

  Specific examples of the constituent material of the substrate body 2 include polyolefins 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), polyether ether ketone (PEEK), polyether imide, polyacetal (POM), polyphenylene oxide, modified polyphenylene oxide, polysulfone, polyether sulfone, polyphenylene sulfide, polyarylate, aromatic polyester (liquid crystal polymer), poly Tetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin, polyvinyl chloride, polyurea Various polyesters, polyesters, polyamides, polybutadienes, transpolyisoprenes, fluororubbers, chlorinated polyethylenes, and other thermoplastic elastomers, epoxy resins, phenol resins, urea resins, melamine resins, unsaturated polyesters, silicones Resins, urethane-based resins, etc., or copolymers, blends, polymer alloys, etc. mainly composed of these, and combinations of one or more of these (for example, blend resins, polymer alloys, laminates) As body etc.).

  The resin material (solidified resin material) constituting the substrate body 2 generally has an absolute refractive index larger than that of various gases (the atmosphere in which the microlens substrate 1 is used). Such a value is preferably 1.35 to 2.00, more preferably 1.40 to 1.60, and even more preferably 1.45 to 1.55. When the absolute refractive index of the resin material is a value within the above range, the viewing angle characteristic can be made particularly excellent while sufficiently increasing the luminance of the projected image.

The microlens substrate 1 includes a plurality of microlenses 21 as convex lenses having a convex surface on the light incident surface side.
In the present embodiment, the microlens 21 has a flat shape (substantially elliptical, substantially bowl-shaped) in which the vertical width (vertical width) when the microlens substrate 1 is viewed in plan is smaller than the horizontal width (horizontal width). have. When the microlens 21 has such a shape, it is possible to make the viewing angle characteristics 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 21 in plan view is X [μm] and the length in the major axis direction (lateral direction) is Y [μm], 0.10 ≦ X / It is preferable that the relationship of Y ≦ 0.99 is satisfied, more preferably the relationship of 0.50 ≦ X / Y ≦ 0.95 is satisfied, and the relationship of 0.60 ≦ X / Y ≦ 0.80 is satisfied More preferably. By satisfying the relationship as described above, the effects as described above become more remarkable.

  The length of the microlens 21 in the short axis direction (width of the microlens 21) when viewed in plan is preferably 10 to 500 μm, more preferably 30 to 300 μm, and more preferably 50 to 100 μm. Further preferred. When the length of the microlens 21 in the short axis direction is a value within the above range, it is possible to obtain sufficient resolution in the image projected on the screen while effectively preventing the occurrence of inconvenience such as moire. The productivity of the microlens substrate 1 (transmission type screen 10) can be further increased.

Further, the length in the major axis direction of the microlens 21 when viewed in plan is preferably 15 to 750 μm, more preferably 45 to 450 μm, and even more preferably 75 to 150 μm. When the length of the microlens 21 in the short axis direction is a value within the above range, it is possible to obtain sufficient resolution in the image projected on the screen while effectively preventing the occurrence of inconvenience such as moire. The productivity of the microlens substrate 1 (transmission type screen 10) can be further increased.
In the cross section of the transmissive screen 10 in the vertical direction (the short axis direction of the microlens 21), the microlens 21 has a radius of curvature near the periphery of the microlens 21 larger than the radius of curvature near the center.

Incidentally, the microlens substrate used in the conventional transmission type screen has excellent viewing angle characteristics in the vertical and horizontal directions, but has a problem that the brightness (luminance) of the image projected on the screen is low.
On the other hand, in the present invention, in the vertical direction of the transmissive screen, the radius of curvature near the periphery of the microlens is larger than the radius of curvature near the center, so The viewing angle characteristics in (direction) can be sufficiently maintained, while the diffusion of the incident light of the microlens in the vertical direction can be suppressed to some extent, and the luminance of the obtained image can be improved. As a result, it is possible to provide a rear projector that has excellent viewing angle characteristics in each direction and can display a high-luminance image.

In the present invention, the microlens has a radius of curvature near the periphery of the microlens in the vertical direction of the transmissive screen, which is larger than the radius of curvature near the center. More specifically, the transmissive screen When the radius of curvature near the periphery of the microlens in the vertical direction is R ₀ [μm] and the radius of curvature near the center is R ₁ [μm], the relationship of 1.5 ≦ R ₀ / R ₁ ≦ 1000 is established. It is preferably satisfied, more preferably 100 ≦ R ₀ / R ₁ ≦ 1000, and still more preferably 200 ≦ R ₀ / R ₁ ≦ 900. By satisfying such a relationship, the effect of the present invention can be made more remarkable.

The radius of curvature near the center of the microlens 21 in the vertical direction of the transmissive screen 10 (the short axis direction of the microlens 21) is preferably 5 to 250 μm, and more preferably 10 to 100 μm. Thereby, the brightness | luminance of the image obtained can be improved, making the viewing angle characteristic of a perpendicular direction (up-down direction) favorable.
When the height of the micro lens 21 in the minor axis direction of the micro lens 21 is H ₂ [μm] and the length of the micro lens 21 in the minor axis direction is X [μm], 2.0 ≦ X / H ₂ ≦ 3 It is preferable to satisfy this relationship, and it is more preferable to satisfy the relationship of 2.0 ≦ X / H ₂ ≦ 2.5. By satisfying such a relationship, it is possible to improve the luminance of the obtained image while improving the viewing angle characteristics in the vertical direction (vertical direction).

In the present embodiment, the cross section of the microlens 21 in the horizontal direction of the transmissive screen 10 (long axis direction of the microlens 21) has a substantially semicircular shape. That is, the radius of curvature is substantially constant both at the center and at the periphery.
When the height of the micro lens 21 in the long axis direction of the micro lens 21 is H ₁ [μm] and the length of the micro lens 21 in the long axis direction is Y [μm], 2.0 ≦ Y / H ₁ ≦ 2. It is preferable to satisfy the relationship of. By satisfying such a relationship, it is possible to make the horizontal viewing angle characteristics particularly excellent while effectively preventing the occurrence of moire due to light interference.
The radius of curvature of the microlens 21 in the major axis direction of the microlens 21 is preferably 5 to 250 μm, and more preferably 10 to 100 μm. Thus, the viewing angle characteristics in the horizontal direction (left-right direction) can be made particularly excellent.

  The plurality of microlenses 21 are arranged in a staggered pattern (in a staggered pattern). By arranging the microlenses 21 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 shape or the like, it may be difficult to sufficiently prevent the occurrence of inconvenience such as moire depending on the size of the microlenses 21 and the like. . Further, when the microlenses are randomly arranged, depending on the size of the microlens 21 or the like, it becomes difficult to sufficiently increase the occupation ratio of the microlenses in the effective region where the microlenses are formed. It is difficult to sufficiently increase the transmittance (light utilization efficiency) of the light, and the obtained image becomes dark.

As described above, the microlenses 21 are arranged in a staggered pattern when the microlens substrate 1 is viewed in plan view. However, the microlenses 21 are adjacent to the first row 25 composed of the plurality of microlenses 21 and adjacent to them. It is preferable that the second row 26 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 and the like are particularly excellent while effectively preventing the occurrence of moire due to light interference. be able to.

Further, when the microlens substrate 1 is viewed in plan from the light incident surface side (direction shown in FIG. 2), the occupation ratio of the microlens 21 is 90% or more in the effective region where the microlens 21 is formed. Preferably, it is 96% or more, and more preferably 97% or more. When the occupation ratio of the microlens 21 is 90% or more, the light utilization efficiency can be further improved. The occupation ratio of the microlens 21 is a line segment connecting the center 212 of the microlens 21 when viewed in plan and the central portion of the portion adjacent to the microlens 21 where the microlens 21 is not formed. It can be determined as a ratio (L ₃ / L ₄ × 100 [%]) between the length L ₃ [μm] of the portion where the microlens 21 is formed and the length L ₄ [μm] of the line segment. (See FIG. 2).

A black matrix 3 is provided on the surface of the substrate body 2 on the light emission side. The black matrix 3 is made of a light-shielding material and is formed in a layer shape. By having such a black matrix 3, the black matrix 3 can absorb external light (external light that is not preferable for forming a projection image), and the image projected on the screen has excellent contrast. Can be.
Such a black matrix 3 has an opening 31 on the optical path of the light transmitted through each microlens 21. Thereby, the light condensed by each micro lens 21 can be efficiently passed through the opening 31 of the black matrix 3. As a result, the light utilization efficiency of the microlens substrate 1 can be increased.

  The black matrix 3 may be made of any material as long as it has a function of absorbing external light (external light that is not desirable for forming a projection image). Examples of materials that can be used include various inorganic materials, various organic materials, composite materials of inorganic materials and organic materials, and more specifically, chromium oxide, chromium, various pigments, various dyes, and the like. be able to.

  The black matrix 3 may be composed of a plurality of types of materials, for example, a laminate having a layer mainly composed of chromium and a layer mainly composed of chromium oxide. Good. When the black matrix 3 has such a configuration, the openings 31 can be easily and reliably formed by a method described later, and the durability of the black matrix 3 is particularly excellent. be able to.

  Further, when the black matrix 3 is composed of various pigments, various dyes, etc., the contrast of the obtained image can be easily made excellent, and a desired site can be obtained by a method as described later. In addition, the opening 31 having a desired size and shape can be formed more easily and reliably. When the black matrix 3 is composed of various pigments, various dyes, etc., various inks can be suitably used for forming the black matrix 3 (as a black matrix forming material). This is also advantageous from the viewpoint of stable production of the lens substrate 1 and reduction of production costs.

  Moreover, the black matrix 3 may contain the material which does not have light-shielding property. For example, the black matrix 3 may include a resin material as a constituent material. Thereby, the adhesion of the black matrix 3 to the substrate body 2 in the microlens substrate 1 finally obtained is made particularly excellent, and in the opening forming step described in detail later, it is composed of a black matrix forming material. The predetermined portion of the formed film can be easily and reliably removed, and the black matrix 3 having the opening 31 having a desired shape can be reliably formed.

As a resin material constituting the black matrix 3, for example, a damar resin or the like can be given.
Further, the thickness (average thickness) of the black matrix 3 is preferably 0.3 to 8.0 μm, more preferably 0.8 to 7.0 μm, and 1.4 to 6.0 μm. More preferably. When the thickness of the black matrix 3 is a value within the above range, the function as the black matrix 3 (that is, the image contrast is improved) while preventing unintentional peeling, cracking, etc. For example, in the transmission screen 10 including the microlens substrate 1, the contrast of the projected image can be made particularly excellent.

  The opening 31 of the black matrix 3 usually has a shape (substantially similar shape) corresponding to the shape of the microlens 21 (shape when viewed in plan) and is smaller than the microlens 21. That is, in the present embodiment, the opening 31 has a flat shape (substantially oval or substantially bowl-shaped) whose vertical width when the microlens substrate 1 is viewed in plan is smaller than the horizontal width. By having the opening 31 having such a shape and size, it is possible to effectively prevent the occurrence of inconvenience such as moire while making the contrast excellent, and to make the viewing angle characteristics particularly excellent. it can.

  The length in the minor axis direction of the opening 31 when seen in a plan view is preferably 5 to 250 μm, more preferably 7 to 150 μm, and still more preferably 15 to 90 μm. When the length in the minor axis direction of the opening 31 is a value within the above range, the use efficiency of light is particularly excellent (particularly a high-luminance image can be projected) and the obtained image The contrast can be made particularly excellent. On the other hand, if the length of the opening 31 in the minor axis direction is less than the lower limit, it may be difficult to sufficiently increase the light use efficiency. Further, if the length of the opening 31 in the minor axis direction exceeds the upper limit, it may be difficult to make the contrast of the obtained image sufficiently excellent.

  Further, the length in the major axis direction of the opening 31 when viewed in plan is preferably 7.5 to 375 μm, more preferably 10.5 to 225 μm, and 22.5 to 135 μm. Is more preferable. When the length in the minor axis direction of the opening 31 is a value within the above range, the use efficiency of light is particularly excellent (particularly a high-luminance image can be projected) and the obtained image The contrast can be made particularly excellent. On the other hand, if the length of the opening 31 in the major axis direction is less than the lower limit value, it may be difficult to sufficiently increase the light use efficiency. If the length of the opening 31 in the major axis direction exceeds the upper limit, it may be difficult to make the contrast of the obtained image sufficiently excellent.

  When the length of the microlens 21 in the short axis direction (longitudinal direction) in plan view is X [μm] and the length of the opening 31 in the short axis direction (vertical direction) is X ′ [μm]. 0.10 ≦ X ′ / X ≦ 0.90 is satisfied, more preferably 0.20 ≦ X ′ / X ≦ 0.80 is satisfied, and 0.30 ≦ X ′. It is more preferable to satisfy the relationship of /X≦0.60. By satisfying the above relationship, the light use efficiency is particularly excellent (particularly a high-luminance image can be projected), and the contrast of the obtained image is particularly excellent. Can do.

  Further, when the length in the major axis direction (lateral direction) of the microlens 21 in plan view is Y [μm], and the length in the major axis direction (lateral direction) of the opening 31 is Y ′ [μm]. 0.10 ≦ Y ′ / Y ≦ 0.90 is satisfied, more preferably 0.20 ≦ Y ′ / Y ≦ 0.80 is satisfied, and 0.30 ≦ Y ′. It is more preferable to satisfy the relationship /Y≦0.60. By satisfying the above relationship, the light use efficiency is particularly excellent (particularly a high-luminance image can be projected), and the contrast of the obtained image is particularly excellent. Can do.

  The light utilization efficiency of the microlens substrate 1 (ratio of the amount of light emitted from the exit surface to the amount of light incident from the entrance surface of the microlens substrate 1) is preferably 60% or more, and 70 % Is more preferable, and 80 to 95% is more preferable. Thereby, an image with particularly high luminance can be projected, and the contrast of the obtained image can be made particularly excellent.

[Transparent screen]
Next, the transmission screen 10 including the microlens substrate 1 as described above will be described.
FIG. 3 is a schematic longitudinal sectional view showing a preferred embodiment of the transmission screen of the present invention provided with the microlens substrate shown in FIG. In the following description, the left side in FIG. 3 is referred to as “(light) incident side” and the right side is referred to as “(light) emission side”.

As shown in FIG. 3, the transmission screen 10 includes a Fresnel lens portion 5 and the microlens substrate 1 described above. The Fresnel lens unit 5 is installed on the light (image light) incident side, and the light transmitted through the Fresnel lens unit 5 is incident on the microlens substrate 1.
The Fresnel lens unit 5 has a prism-shaped Fresnel lens 51 formed in a substantially concentric shape on the exit side surface. The Fresnel lens unit 5 refracts image light from a projection lens (not shown) to produce parallel light La parallel to the vertical direction of the main surface of the microlens substrate 1.

In the transmissive screen 10 configured as described above, the image light from the projection lens is refracted by the Fresnel lens unit 5 and becomes parallel light La. The parallel light La is incident on the surface of the microlens substrate 1 opposite to the surface on which the black matrix 3 is provided, is condensed by each microlens 21, and is then diffused. At this time, the light incident on the microlens substrate 1 is transmitted through the microlens substrate 1 with sufficient transmittance. The light that has passed through the opening 31 diffuses and is observed as a planar image by the observer.
Since the transmissive screen 10 described above includes the microlens substrate 1 as described above, it has excellent viewing angle characteristics in each direction and can display a high-luminance image.

The microlens substrate 1 described above may be manufactured by any method, but can be preferably manufactured by a method as described below.
[Microlens substrate manufacturing method]
First, an example of a method for manufacturing the microlens substrate 1 will be described.
First, the substrate with recesses (substrate with recesses for forming microlenses) 6 used in the manufacturing method of the present embodiment and the manufacturing method thereof will be described.

  FIG. 4 is a schematic longitudinal sectional view showing a substrate with recesses used for manufacturing a microlens substrate, and FIGS. 5 and 6 are schematic longitudinal sectional views showing a method for manufacturing the substrate with recesses shown in FIG. In manufacturing a substrate with recesses, a large number of recesses (microlens forming recesses) are actually formed on the substrate. In manufacturing a microlens substrate, a large number of microlenses (convex lenses) are actually formed on the substrate. However, in order to make the explanation easier to understand, a part thereof is highlighted. 4 to 6 show cross sections in the minor axis direction of the recesses (direction corresponding to the vertical direction of the transmission screen).

  The substrate with recesses (substrate with recesses for forming microlenses) 6 may be made of any material, but is preferably made of a material that is less likely to bend and is less likely to be damaged. Examples of the constituent material of the substrate 6 with recesses include soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass. Especially, as a constituent material of the board | substrate 6 with a recessed part, soda glass, crystalline glass (for example, neo-serum etc.), and an alkali free glass are preferable. Soda glass, crystalline glass, and alkali-free glass are easy to process, are relatively inexpensive, and are advantageous from the viewpoint of manufacturing cost.

  The substrate with recesses (substrate with recesses for forming microlenses) 6 includes a plurality of recesses (recesses for forming microlenses) 61 arranged in a manner corresponding to the arrangement method of the microlenses 21 (transferred positional relationship). ing. These concave portions 61 are concave portions, whereas the micro lens 21 is a convex portion, and have a shape corresponding to the micro lens 21 (substantially the same shape except for the transferred shape) and dimensions. is doing.

  More specifically, in this embodiment, the recess (microlens forming recess) 61 has a vertical width (vertical width) smaller than a horizontal width (horizontal width) when the substrate 6 with recesses is viewed in plan view. It has a flat shape (substantially oval or substantially bowl-shaped). The concave portion 61 having such a shape is preferably used for manufacturing the microlens substrate 1 capable of effectively preventing the occurrence of inconvenience such as moire and having particularly excellent viewing angle characteristics. Can do.

  Further, when the length in the minor axis direction (longitudinal direction) of the recess 61 in plan view is X [μm] and the length in the major axis direction (lateral direction) is Y [μm], 0.10 ≦ X /Y≦0.99, preferably 0.50 ≦ X / Y ≦ 0.95, more preferably 0.60 ≦ X / Y ≦ 0.80. It is more preferable to satisfy. By satisfying the relationship as described above, the effects as described above become more remarkable.

  Moreover, it is preferable that the length (width | variety of the recessed part 61) of the short axis direction of the recessed part 61 when planarly viewed is 10-500 micrometers, It is more preferable that it is 30-300 micrometers, It is 50-100 micrometers. Further preferred. When the length in the minor axis direction of the recess 61 is a value within the above range, it is possible to obtain sufficient resolution in the image projected on the screen while effectively preventing the occurrence of inconvenience such as moire. The productivity of the microlens substrate 1 (substrate 6 with a recess) 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 in the minor axis direction of the recess 61 is a value within the above range, it is possible to obtain sufficient resolution in the image projected on the screen while effectively preventing the occurrence of inconvenience such as moire. The productivity of the microlens substrate 1 (substrate 6 with a recess) can be further increased.

  Further, in the recess 61, the radius of curvature near the periphery of the recess 61 is larger than the radius of curvature near the center in the cross section in the minor axis direction of the recess 61. Thereby, in the finally obtained transmissive screen 10, diffusion of the incident light in the vertical direction of the microlens 21 to some extent is performed while sufficiently maintaining the viewing angle characteristics in the vertical direction (vertical direction) of the transmissive screen 10. And the luminance of the obtained image can be improved. As a result, it is possible to provide a rear projector that has excellent viewing angle characteristics in each direction and can display a high-luminance image.

Further, in the minor axis direction of the concave portion 61, when the radius of curvature near the peripheral portion of the concave portion 61 is R ₀ [μm] and the radius of curvature near the center is R ₁ [μm], 1.5 ≦ R ₀ / R ₁ The relationship of ≦ 1000 is preferably satisfied, the relationship of 100 ≦ R ₀ / R ₁ ≦ 1000 is more preferable, and the relationship of 200 ≦ R ₀ / R ₁ ≦ 900 is more preferable. By satisfying such a relationship, it is possible to display a high-luminance image while maintaining excellent viewing angle characteristics in the finally obtained transmission screen.
The radius of curvature near the center of the recess 61 in the minor axis direction of the recess 61 is preferably 5 to 250 μm, and more preferably 10 to 100 μm. Thereby, the brightness | luminance of the image obtained can be improved, making the viewing angle characteristic of a perpendicular direction (up-down direction) favorable.

When the height of the recess 61 in the minor axis direction of the recess 61 is D ₂ [μm] and the length of the recess 61 in the minor axis direction is X [μm], a relationship of 2.0 ≦ X / D ₂ ≦ 3 is established. It is preferable to satisfy, and it is more preferable to satisfy the relationship of 2.0 ≦ X / D ₂ ≦ 2.5. By satisfying such a relationship, it is possible to improve the luminance of the obtained image while improving the viewing angle characteristics in the vertical direction (vertical direction).
Further, the cross section in the major axis direction of the recess 61 has a substantially semicircular shape.

When the depth of the recess 61 in the major axis direction of the recess 61 is D ₁ [μm] and the length of the recess 61 in the major axis direction is Y [μm], 2.0 ≦ Y / D ₁ ≦ 2.2 Satisfying the relationship. By satisfying such a relationship, it is possible to make the horizontal viewing angle characteristics particularly excellent while effectively preventing the occurrence of moire due to light interference.
Moreover, it is preferable that the curvature radius of the recessed part 61 in the major axis direction of the recessed part 61 is 5-250 micrometers, and it is more preferable that it is 10-100 micrometers. Thus, the viewing angle characteristics in the horizontal direction (left-right direction) can be made particularly excellent.

  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 depending on the size of the concave portions (microlenses). In addition, when the concave portions are randomly arranged, depending on the size of the concave portion (microlens) or the like, it becomes difficult to sufficiently increase the occupancy ratio of the concave portions in the effective region where the concave portions are formed. It becomes difficult to sufficiently increase the transmittance (light utilization efficiency), and the obtained image becomes dark.

  In addition, as described above, the recesses 61 are arranged in a staggered pattern when the substrate 6 with recesses is viewed in plan, and are adjacent to the first row composed of the plurality of recesses 61. The second row is preferably 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, the concave portion 61 has been described as having substantially the same shape (dimension) and arrangement method as the microlens 21. However, for example, the constituent material of the substrate body 2 contracts. When it is easy (when the resin material constituting the substrate body 2 shrinks due to solidification or the like), the shape (dimensions) between the microlens 21 and the concave portion 61 is considered in consideration of the shrinkage rate. Occupancy ratios and the like may be different.

Next, a method for manufacturing the substrate with recesses will be described with reference to FIGS. 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 of them is shown highlighted.
First, when manufacturing the board | substrate 6 with a recessed part, the board | substrate 7 is prepared.
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.

Such cleaning can be performed, for example, by etching (light etching) the surface of the substrate 7.
The etching method is not particularly limited, and examples thereof include wet etching and dry etching.
When wet etching is used, the etching solution is not particularly limited, but a mixed solution of ammonium monohydrogen difluoride and sulfuric acid is preferably used. Thereby, the smoothness of the surface of the substrate 7 can be increased, and impurities (Na, K, etc.) on the surface of the substrate 7 can be suitably removed. As a result, the mask forming film 4 (mask 8) can be more uniformly formed in the masking step described later. In addition, the adhesion between the mask forming film 4 (mask 8) and the substrate 7 can be improved. As a result, it is possible to prevent the mask 8 from being unintentionally peeled off in an etching process described later.

<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 process, FIGS. 5A and 5B).
In particular, in the present embodiment, first, as shown in FIG. 5A, 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). (Formation film forming step) Thereafter, as shown in FIG. 5B, the mask 8 is obtained by forming the initial hole 81 in the mask formation film 4 (initial hole formation step). 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). . Moreover, the recessed part 61 of the shape as mentioned above can be formed suitably in the etching process mentioned 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 0.01 to 2.0 μm, preferably 0.03 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. 5B, 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. Further, by forming the initial hole 81 by laser irradiation, a substrate with a recess 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 of the depth of each recessed part 61 which comprises the board | substrate 6 with a recessed part also becomes small, and the dispersion | variation in the magnitude | size of each microlens 21 of the microlens substrate 1 finally obtained also becomes small. As a result, the variation in diameter, focal length, and lens thickness of each microlens 21 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 FIGS. 5C and 5D, the substrate 7 is etched using the mask 8 in which the initial holes 81 are formed (etching step). Thereby, a large number of recesses 61 are formed on the substrate 7.
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, as shown in FIG. It is etched.
Then, in the minor axis direction of the recess 61 to be formed, as shown in FIG. 5 (d), the recess 61 ′ being formed comes into contact with the adjacent recesses. That is, the peripheral edge 62 of the recess 61 ′ in the minor axis direction of the recess 61 to be formed is separated from the mask 8.
In this way, the peripheral edge 62 is also etched by separating the peripheral edge 62 from the mask 8. As the etching of the peripheral edge 62 proceeds, the radius of curvature of the peripheral edge of the recess 61 ′ becomes larger than the center of the recess 61 ′. As a result, as shown in FIG. 6E, a large number of recesses 61 having the shape as described above are formed on the substrate 7.

Further, 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 in the surface of the substrate 7). ).
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 improves and the board | substrate 6 with a recessed part can be provided cheaply.

<A3> Next, as shown in FIG. 6F, the mask 8 is removed (mask removal step). At this time, the substrate with recesses 6 is obtained by removing the back surface protective film 89 along with the removal of the mask 8.
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 substrate 6 with the recesses where the recesses 61 are provided. Thereby, in the method of manufacturing the microlens substrate 1 described in detail later, the substrate 6 with the recesses can be easily removed while sufficiently preventing defects such as chipping from occurring on the microlens 21 of the substrate body 2. . 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. 6F and 4, the substrate 6 with recesses 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 improves and the board | substrate 6 with a recessed part can be provided cheaply.

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 substrate with a concave portion (microlens 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 microlens substrate 1 using the above-described substrate 6 with recesses will be described.
7 and 8 are schematic longitudinal sectional views showing an example of a method for manufacturing the microlens substrate shown in FIG. In the following description, the lower side in FIGS. 7 and 8 is referred to as “(light) incident side”, and the upper side is referred to as “(light) emission side”.

  <B1> First, as shown in FIG. 7A, the resin material 23 having fluidity (for example, the resin material 23 in a softened state, An unpolymerized (uncured) resin material 23) is applied, and the resin material 23 is pressed by the flat plate 11. In particular, in this embodiment, the resin material 23 is pressed in a state where the spacer 20 is disposed between the substrate 6 with recesses and the flat plate 11. Thereby, the thickness of the microlens substrate 1 to be formed can be more reliably controlled, and the focal position of the microlens 21 on the finally obtained microlens substrate 1 can be more reliably controlled. And the occurrence of inconvenience such as color unevenness can be more effectively prevented.

  The spacer 20 is made of a material having a refractive index comparable to that of the resin material 23 (solidified resin material 23). By using the spacer 20 made of such a material, even when the spacer 20 is arranged at the portion where the recess 61 of the substrate 6 with recesses is formed, the microlens substrate 1 from which the spacer 20 is obtained can be obtained. An adverse effect on optical characteristics can be effectively prevented. Accordingly, it is possible to arrange a relatively large number of spacers 20 over substantially the entire effective area of the main surface (the surface side where the recesses are formed) of the substrate 6 with recesses. As a result, the substrate 6 with recesses, the flat plate Therefore, the thickness of the resulting microlens substrate 1 can be more reliably controlled.

  As described above, the spacer 20 is made of a material having the same refractive index as that of the resin material 23 (the resin material 23 after solidification). More specifically, the absolute refraction of the constituent material of the spacer 20 is used. The absolute value of the difference between the refractive index and the absolute refractive index of the resin material 23 after solidification is preferably 0.20 or less, more preferably 0.10 or less, and further preferably 0.02 or less. Preferably, the solidified resin material 23 and the spacer 20 are most preferably composed of the same material.

The shape of the spacer 20 is not particularly limited, but is preferably substantially spherical or substantially cylindrical. When the spacer 20 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.
In the case where the spacer 20 is used as described above, when the resin material 23 is solidified, it is sufficient that the spacer 20 is disposed between the substrate 6 with recesses and the flat plate 11, and the timing for supplying the spacer 20 is particularly It is not limited. For example, the resin material 23 in which the spacer 20 is dispersed in advance as the resin to be applied may be used on the surface of the substrate 6 with the recess where the recess 61 is formed, or the spacer 20 is disposed on the substrate 6 with the recess. The resin material 23 may be applied in a state, or the spacer 20 may be applied after the resin material 23 is supplied.
Further, the flat plate 11 may have a surface on which the resin material 23 is pressed subjected to the release treatment as described above. Thereby, the flat plate 11 can be efficiently removed from the surface of the substrate body 2 in a process described later.

<B2> Next, the resin material 23 is solidified (including curing (polymerization)), and then the flat plate 11 is removed (see FIG. 7B). Thereby, the substrate main body 2 provided with the microlens 21 (particularly, the microlens 21 satisfying the conditions such as the shape and the arrangement as described above) made of the resin filled in the concave portion 61 is obtained.
When the resin material 23 is solidified by curing (polymerization), examples of the method include irradiation with light such as ultraviolet rays, irradiation with electron beams, and heating.

<B3> Next, as shown in FIG. 7C, a colored black matrix-forming material (light-shielding film-forming material) is applied to the exit-side surface of the substrate body 2, and the black matrix-forming material is used. The formed film 32 is formed (light shielding film forming material application step).
The method for applying the black matrix forming material to the surface of the substrate body 2 is not particularly limited. For example, dip coating, doctor blade, spin coating, brush coating, spray coating, electrostatic coating, electrodeposition coating, roll coater, etc. Various coating methods, vapor deposition methods, ion plating methods, vapor phase film formation methods such as sputtering methods, wet plating methods such as electrolytic plating and electroless plating, and the like can be applied. In particular, when the black matrix 3 is formed as a laminate having a layer mainly composed of chromium and a layer mainly composed of chromium oxide, the film 32 is preferably formed by a vapor deposition method. Further, when the black matrix 3 is formed as a material composed of a material containing a pigment or dye (particularly, a material composed of a material including a resin material in addition to the pigment or dye), the black matrix 3 is formed by a coating method. Is preferred. Thereby, the film | membrane 32 of uniform thickness can be formed easily.

  When the black matrix 3 is formed of a material including a pigment or a dye, the black matrix forming material includes a resin material and a liquid medium (for example, a solvent, a dispersion medium, in addition to the pigment and the dye). A liquid that functions as a liquid). Thereby, the film 32 having a uniform thickness can be formed easily and reliably, and the adhesion of the formed film 32 (black matrix 3) to the substrate body 2 can be made particularly excellent. . Further, if the black matrix forming material is composed of a material including a resin material and a liquid medium in addition to a pigment and a dye, a predetermined portion of the film 32 is formed in an opening forming step described in detail later. Can be easily and reliably removed, and the black matrix 3 having the openings 31 having a desired shape can be more reliably formed.

In this step, a treatment for removing a part of the components constituting the black matrix forming material may be performed in the subsequent step. For example, when the black matrix forming material is made of a material containing a liquid medium, for example, a process for removing the liquid medium from the film 32 made of the black matrix forming material (for example, heat treatment) , Decompression treatment or the like).
The thickness of the film 32 formed in this step is usually substantially the same as the thickness of the black matrix 3. Therefore, the thickness (average thickness) of the film 32 is preferably 0.3 to 8.0 μm, more preferably 0.8 to 7.0 μm, and 1.4 to 6.0 μm. Is more preferable.

  <B4> Next, as shown in FIG. 8D, the substrate body 2 is removed from the substrate 6 with recesses. Thus, by removing the substrate 6 with recesses from the substrate body 2, the removed substrate 6 with recesses can be repeatedly used for the manufacture of the substrate body 2 (microlens substrate 1). This is advantageous for improving the stability of the quality of the substrate body 2 (microlens substrate 1).

  <B5> Next, as shown in FIG. 8E, the substrate body 2 is irradiated with a laser beam Lb in a direction perpendicular to the incident-side surface. The irradiated laser beam Lb is refracted and collected by entering the microlens 21. And the film | membrane (film | membrane comprised with the material for light shielding film formation) 32 of the site | part irradiated with the laser beam which became high energy by condensing is removed, and the opening part 31 is formed (FIG. 7 ( f)). Thereby, the microlens substrate 1 having the black matrix (light shielding film) 3 is obtained.

As described above, in this embodiment, a part of the film made of the light shielding film forming material is removed by the energy of the focused laser beam, and the opening 31 is formed. As described above, by using the light condensed by the microlens (particularly, laser light having a uniform frequency and phase), only a predetermined portion of the film made of the colored light-shielding film forming material is selectively selected. Can be removed. In other words, by using the laser beam condensed by the microlens to form the opening, light having a high energy density can be selectively given only to a specific part, and the opening is formed of a light shielding film forming material. In addition, it is possible to selectively remove the opening portion of the film, and to effectively prevent the other portion from being adversely affected. Moreover, according to this embodiment, the light shielding film which has the opening part of a desired shape in a desired site | part can be reliably formed with a simple method with few processes. As a result, an image obtained by using the microlens substrate can have excellent light utilization efficiency and excellent contrast.
In addition, since the laser light is generally light having a uniform frequency and phase, by selecting the type of laser light according to the film made of the light shielding film forming material and the constituent material of the microlens substrate, It is possible to more reliably prevent the occurrence of adverse effects on the portions of the film composed of the substrate body and the light shielding film forming material that should remain.

The type of laser light used in this step is not particularly limited. For example, ruby laser, semiconductor laser, YAG laser, femtosecond laser, glass laser, YVO ₄ laser, Ne-He laser, Ar laser, CO ₂ laser, excimer A laser etc. are mentioned. Moreover, you may use wavelengths, such as SHG of each laser, THG, and FHG.
Note that a series of processes such as application of the light shielding film forming material and laser light irradiation as described above may be repeated. Thereby, the light shielding film (black matrix) can be formed thicker, and the contrast can be further improved.

[Rear type projector]
A rear projector using the transmission screen will be described below.
FIG. 11 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 transmissive screen 10 are arranged in a housing 340.

Since the rear projector 300 includes the transmissive screen 10 as described above, it is possible to obtain an image with high brightness and excellent contrast. Further, since the transmission type screen 10 (microlens substrate 1) as described above is provided, the viewing angle characteristics and the like are particularly excellent.
In particular, in the microlens substrate 1 described above, since the elliptical microlenses 21 are arranged in a staggered pattern (in a staggered pattern), the rear projector 300 is not particularly susceptible to problems such as moire.

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 microlens substrate, the transmissive screen, and the rear projector can be replaced with any structure that can exhibit the same function.
Moreover, the manufacturing method of a board | substrate with a recessed part is not limited to the method mentioned above. The substrate with recesses is formed, for example, by forming a hemispherical recess once, forming a mask in the vicinity of the periphery of the recess in a direction corresponding to the vertical direction of the transmission screen, and further performing etching. It may be a thing. In addition, when the concave portion becomes a predetermined size, the etching is temporarily stopped, and the altered portion is formed by the laser in the vicinity of the peripheral portion of the concave portion in the direction corresponding to the vertical direction of the transmission screen, and then etched again. It may be done.

  In the above-described embodiment, the spacer has been described as having a refractive index comparable to that of the resin (resin after solidification). However, the spacer is substantially formed with a concave portion of the substrate with the concave portion. In the case of being disposed only in the non-effective region (ineffective region), it may not have a refractive index comparable to that of the resin (resin after solidification). In manufacturing the microlens substrate, the above spacers are not necessarily used.

  In the above-described embodiment, the resin is applied to the surface of the substrate with recesses. However, for example, by applying resin to the surface of a flat plate and pressing it with the substrate with recesses, It may be manufactured.

  Further, in the above-described embodiment, the initial hole forming step of the manufacturing method of the substrate with recesses is described as forming the initial recesses 71 in the substrate 7 together with the initial holes 81. However, such initial recesses 71 are formed. It does not have to be. 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.

Moreover, in embodiment mentioned above, in manufacture of a microlens substrate, a board | substrate with a recessed part does not necessarily need to be removed as what remove | eliminates a board | substrate with a recessed part. In other words, the substrate with recesses may constitute a part of the microlens substrate.
In the embodiment described above, the opening is formed after the substrate with the recess is removed from the substrate body. However, the opening may be formed before the substrate with the recess is removed. Moreover, you may perform provision of the light shielding film forming material, after removing the board | substrate with a recessed part.

In the above-described embodiment, the transmission screen is described as including a microlens substrate and a Fresnel lens. However, the transmission screen of the present invention does not necessarily include a Fresnel lens. For example, the transmission screen of the present invention may be substantially constituted only by a microlens substrate.
In the above-described embodiment, the microlenses in the microlens substrate and the recesses in the substrate with recesses are described as being arranged in a staggered manner, but the microlenses and the recesses may be arranged in any manner, For example, it may be arranged in a square lattice shape or a honeycomb shape. Moreover, the microlens and the recess may be formed randomly.
In the above-described embodiment, the microlens substrate has been described as having a black matrix. However, the microlens substrate may not have a black matrix.

  Further, the transmission screen of the present invention may have a diffusion part and a diffusion plate having a function of diffusing light transmitted through the substrate body. With such a configuration, for example, the viewing angle characteristics of a transmissive screen and a rear projector can be further improved.

[Production of microlens substrate and transmissive screen]
Example 1
A substrate with recesses having recesses for forming microlenses 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 7.36 wt% concentrated sulfuric acid 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 forming a mask.
The laser processing was performed using an excimer laser under the conditions of an energy density of 1 J / cm ² , a beam diameter of 2 μm at the processing point, and a scanning speed of 0.1 m / sec.
Thereby, initial holes having a predetermined length were formed in a staggered pattern over the entire range of the mask forming film. The average width of the initial holes was 2 μm, and the average length was 2 μm.
At this time, a concave portion (initial concave portion) having a depth of 50 mm was 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 70 μm, and the length in the major axis direction was 107 μm. Further, the ratio R ₀ / R ₁ between the radius of curvature R ₀ near the peripheral edge of the recess in the minor axis direction and the radius of curvature R ₁ near the center was 900. Further, the radius of curvature near the center and the depth of the concave portion in the cross section in the minor axis direction were 32 μm. Further, the radius of curvature of the concave portion in the major axis direction was 53.5 μm, and the depth was 50 μm. Moreover, the occupation rate of the recessed part in the effective area | region in which the recessed part was formed was 98%.
In the wet etching, an aqueous solution containing 4 wt% ammonium monohydrogen difluoride and 7.36 wt% concentrated sulfuric acid 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 substrate with recesses in which a large number of recesses for forming microlenses were arranged in a staggered pattern on a soda glass substrate as shown in FIG. When the obtained substrate with recesses 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, unpolymerized (uncured) acrylic resin (PMMA resin (methacrylic resin)) was applied to the surface of the substrate with recesses on the side where the recesses were formed. Under the present circumstances, the substantially spherical spacer (diameter 50 micrometers) comprised with the hardened | cured material of acrylic resin (PMMA resin (methacrylic resin)) was distribute | arranged to the substantially whole surface of the board | substrate with a recessed part. The spacers were arranged at a rate of about 3 pieces / cm ² .

Next, the acrylic resin was pressed with a flat plate made of soda glass. At this time, air was prevented from entering between the flat plate and the acrylic resin. Moreover, as a flat plate, the surface on which the acrylic resin is pressed is subjected to a gas phase surface treatment (mold release treatment) with hexamethyldisilazane.
Thereafter, the acrylic resin was cured by heating to 120 ° C., and a substrate provided with a large number of microlenses (microlenses having no flat portion) was obtained. The obtained substrate (cured resin) had a refractive index n ₁ of 1.51. The thickness of the resin layer (excluding the microlens) of the obtained substrate was 50 μm. The flat (substantially oval) microlens had a short axis length (diameter) of 70 μm and a long axis length of 107 μm. The ratio R ₀ / R ₁ between the radius of curvature R ₀ near the peripheral edge of the microlens and the radius of curvature R ₁ near the center in the short axis direction was 900. The curvature radius near the center was 53.5 μm. The height of the microlens in the cross section in the minor axis direction was 32 μm. Further, the radius of curvature of the microlens in the major axis direction was 53.5 μm and the height was 50 μm. Further, the occupation ratio of the microlens in the effective region where the microlens is formed was 100%.

Next, the flat plate was removed.
Next, a colored light-shielding film forming material containing a black pigment was applied to the surface of the substrate on the emission side (surface opposite to the surface on which the microlenses are formed) by a roll coater (light-shielding film forming material). Application step). As the light-shielding film forming material, a mixture containing 10 wt% black pigment, 20 wt% damar resin, and 70 wt% xylene (liquid medium) was used.
Thereafter, xylene was removed from the light-shielding film forming material applied to the substrate, thereby forming a film covering the entire emission side of the substrate. The average thickness of the formed film was 5 μm.

Next, the substrate with recesses was removed from the substrate provided with the light shielding film forming material.
Next, a laser beam in the vertical direction was irradiated from the surface of the substrate body on which the microlens was formed to the incident-side surface of the substrate body (opening forming step). As a result, the laser light is condensed by the microlens, and only the vicinity of the condensing portion of the microlens is selectively removed from the film, and the black matrix having a large number of openings is coated on the substrate body. Thus obtained microlens substrate was obtained. The opening had a flat shape (substantially elliptical shape), and the length (diameter) in the minor axis direction was 23 μm and the length in the major axis direction was 30 μm. The formed black matrix had a thickness of 5 μm.
A transmissive screen as shown in FIG. 3 was obtained by assembling the microlens substrate manufactured as described above and the Fresnel lens portion manufactured by extrusion molding.

(Examples 2 to 4)
By adjusting the laser light irradiation conditions (the shape of the initial holes to be formed, the depth of the initial recesses) and the immersion time in the etching solution when forming the substrate with recesses, the shape and arrangement of the recesses of the substrate with recesses A microlens substrate and a transmissive screen were produced in the same manner as in Example 1 except that the pattern was as shown in Table 1.

(Comparative example)
The microlens substrate and the transmission were made in the same manner as in Example 1 except that the microlens substrate manufactured using the substrate with recesses in which the pitches of the initial holes and the etching time were adjusted and the hemispherical recesses were formed. A mold screen was produced.
Tables 1 and 2 collectively show the microlens shape, array pattern, and black matrix configuration of the manufactured microlens substrate for each of the examples and comparative examples.

[Evaluation of image brightness (light utilization efficiency)]
The luminance of the image (light utilization efficiency) was evaluated for the transmissive screens of the examples and comparative examples.
The evaluation of the luminance (light utilization efficiency) of the image is based on the luminance B of light measured on the light exit surface side of the transmissive screen when white light of A (= 300) [cd / m ² ] is incident. This was carried out by determining the ratio (B / A) of [cd / m ² ]. It can be said that the larger the value of B / A, the better the light utilization efficiency.

[Production of rear projector]
Using the transmissive screens of the respective Examples and Comparative Examples, rear type projectors as shown in FIG. 9 were produced.
[Evaluation of viewing angle characteristics]
In a bright room, white display was performed on the transmissive screens of the rear projectors of the examples and comparative examples. In this state, the brightness of the screen (white luminance) from a position at an angle of 30 ° in each of the vertical direction and the horizontal direction from the direction perpendicular to the surface of the transmission screen was measured using a luminance meter.
These results are summarized in Table 2.

  As is apparent from Table 2, in the present invention, a high-brightness image was obtained (excellent light use efficiency) and the viewing angle characteristics were also excellent. On the other hand, in the comparative example, a satisfactory result was not obtained.

It is a top view which shows suitable embodiment of the micro lens board | substrate used for the transmission type screen of this invention. It is a longitudinal cross-sectional view in the vertical direction of the microlens substrate shown in FIG. It is a typical longitudinal cross-sectional view which shows suitable embodiment of the transmission type screen of this invention provided with the microlens board | substrate shown in FIG. It is a typical longitudinal cross-sectional view which shows the board | substrate with a recessed part used for manufacture of a microlens board | substrate. It is a typical longitudinal cross-sectional view which shows the manufacturing method of the board | substrate with a recessed part shown in FIG. It is a typical longitudinal cross-sectional view which shows the manufacturing method of the board | substrate with a recessed part shown in FIG. It is a typical longitudinal cross-sectional view which shows an example of the manufacturing method of the micro lens board | substrate shown in FIG. It is a typical longitudinal cross-sectional view which shows an example of the manufacturing method of the micro lens board | substrate shown in FIG. It is a figure which shows typically the rear type projector to which the transmission type screen of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Micro lens board | substrate 2 ... Board | substrate body 21 ... Micro lens (convex lens) 212 ... Center 23 ... Resin material 25 ... 1st row | line 26 ... 2nd row 3 ... Black matrix (light-shielding film) 31 ... Opening part 32 ... Film | membrane (Film made of light-shielding film forming material) 4 ... mask forming film 5 ... Fresnel lens portion 51 ... Fresnel lens 6 ... substrate with recesses (substrate with recesses for microlens formation) 61 ... recesses (recesses for microlens formation) ) 61 ′: recessed portion (recessed portion for forming a microlens) 62, peripheral edge portion 7, substrate 71, initial recessed portion 8, mask 81, initial hole (opening portion) 89, rear surface protective film 11, flat plate 10, transmissive screen 20, spacer 300 ... Rear projector 310 ... Projection optical unit 320 ... Light guide mirror 340 ... Case

Claims (9)

A transmissive screen including a microlens substrate on which a large number of microlenses are formed,
A transmissive screen, wherein a radius of curvature near a peripheral edge of the microlens in a vertical direction of the transmissive screen is larger than a radius of curvature near a center. 1.5 ≦ R ₀ / R ₁ ≦ where R ₀ [μm] is the radius of curvature near the periphery of the microlens and R ₁ [μm] near the center in the vertical direction of the transmission screen. The transmissive screen according to claim 1, wherein the relationship of 1000 is satisfied.   The transmissive screen according to claim 1 or 2, wherein a radius of curvature of the microlens in a horizontal direction of the transmissive screen is 5 to 250 µm.   The transmissive screen according to any one of claims 1 to 3, wherein the microlens has a flat shape in which a vertical width when the microlens substrate is viewed in plan is smaller than a horizontal width.   The microlens satisfies a relationship of 0.001 ≦ X / Y ≦ 1.40, where X [μm] in the minor axis direction and Y [μm] in the major axis direction. 4. The transmission screen according to 4.   The transmissive screen according to claim 4 or 5, wherein a length of the microlens in a major axis direction is 10 to 500 µm.   The transmission screen according to any one of claims 4 to 6, wherein a length of the microlens in a minor axis direction is 10 to 400 µm.   The first row composed of a plurality of microlenses and a second row adjacent to the microlens substrate in plan view are shifted from each other by a half pitch in the lateral direction. The transmission screen according to any one of the above.   A rear projector comprising the transmissive screen according to claim 1.

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