JP3829358B2 - Planar lens and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to light that diffuses light from a transmissive screen of a rear projection display device, a viewing angle widening plate such as a liquid crystal display device, a plasma display device, and an electroluminescence display device, a backlight for liquid crystal, and various illumination light sources. The present invention relates to a planar lens used for a diffusion plate or the like.
[0002]
[Prior art]
In recent years, a projection display device using a light valve such as a liquid crystal panel that emits a light beam having polarization characteristics has been developed. In the projection display device using this liquid crystal, image light spatially modulated by the liquid crystal panel is enlarged and projected onto a screen by a projection lens. The projection display device includes a front projection type and a rear projection type.
[0003]
FIG. 15 is a schematic configuration diagram of a rear projection display device that observes an image projected from the screen rear side from the front of the screen. As shown in FIG. 15, the rear projection type display device includes a projection optical system 1 for emitting light, a transmissive screen 2, and a light transmissive screen that reflects light L emitted from the projection optical system 1. 2 and a guiding mirror 3.
This transmissive screen 2 is usually composed of a Fresnel lens 4 and a lenticular lens 5 as shown in a schematic cross-sectional view of the main part in FIG.
[0004]
In the rear projection display device having the above-described configuration, the light L projected from the projection optical system 1 becomes substantially parallel light by the Fresnel lens 4 and further diffused left and right by the lenticular lens 5.
Thus, in this conventional normal rear projection display device, the image light emitted from the projection optical system 1 is enlarged and projected onto the transmissive screen 2. That is, the observer observes the projection image as the transmitted light of the transmission screen 2 from the opposite side of the projection optical system 1.
[0005]
By the way, in general, the rear projection type display device is often used in a bright room. In this case, disturbance light such as room illumination is reflected on the surface of the lenticular lens 5, and this is emitted from the transmission screen together with the image light. There was a problem that the contrast was lowered. Conventionally, as a countermeasure against this, a smoke plate (not shown) is separately provided on the front surface of the lenticular lens 5 to absorb a part of disturbance light, thereby taking a method of suppressing a decrease in contrast. Yes.
[0006]
[Problems to be solved by the invention]
By the way, when the smoke plate is provided as described above, a part of the image light is similarly absorbed when passing through the smoke plate, and the luminance of the image is lowered. Therefore, a light source with higher power consumption must be used. There is a problem that sufficient luminance cannot be obtained. In addition, when the power consumption is increased in this way, a more severe heat countermeasure is required, which causes a new problem of increasing the cost.
[0007]
Further, as described above, the lenticular lens diffuses image light mainly in the left and right (horizontal) direction, so that the image can be observed even when viewed from an oblique direction, but in the vertical (vertical) direction orthogonal to this. Has a disadvantage that the range in which a clear image can be observed is extremely narrow when the viewpoint is moved up and down.
[0008]
In addition, since the lenticular lenses are regularly arranged with linear lenses extending in the vertical direction, there is a problem that moire interference fringes are generated in the image and the image quality is remarkably lowered.
[0009]
In addition, the lenticular lens has a precise lens shape that covers the entire surface, and even if a slight defect occurs in the entire lens, it cannot be used as a whole. Need to pay. Furthermore, with the recent increase in the projected area of the image, the handling of the screen becomes more problematic, and the situation is such that high costs cannot be avoided.
[0010]
In the present invention, the above-mentioned problems can be solved, the generation of moire interference fringes can be improved, the diffusion in both horizontal and vertical directions can be performed well, and both the horizontal and vertical viewing angles can be expanded, Also provided are a flat lens with high contrast and high image quality, and a method for manufacturing the same.
[0011]
[Means for Solving the Problems]
  The planar lens according to the present invention includes a transparent base material, a colored hot melt adhesive layer formed on the light incident side surface of the transparent base material, and the colored hot melt adhesive layer.BuriedNumerous microspherical transparent beads consisting of a single layer attachedThe colored hot melt adhesive layer is composed of a transparent layer disposed on the transparent substrate side, and a colored layer formed on the light incident side thereon, and the microspherical transparent beads Is embedded in the light incident side so as to be exposed from the colored hot-melt adhesive layer by 50% or more of the diameter in the depth direction.
[0012]
Although the transparent base material itself can be constituted by a substrate having rigidity, the transparent base material is formed of a film-like base material, and the transparent base material is rigidly attached to the light emitting side surface via a transparent adhesive. The transparent substrate can be bonded.
[0013]
In the present specification, the term “transparent” means that the target light, that is, the light to be transmitted through the lens, can be transmitted, and includes so-called translucent.
[0015]
The microsphere-like transparent beads are arranged in a state where a portion of 30% or more of the diameter is exposed from the colored hot melt adhesive layer to the light incident side. This is because when the exposure level is within this range, the exposed area of the beads increases and the amount of incident light increases, thereby increasing the brightness of the image light. Therefore, it is more preferable to expose 40% or more of the diameter of the transparent beads, and it is more preferable to expose 50% or more.
[0016]
The colored hot melt adhesive layer or the colored layer constituting the colored hot melt adhesive layer is preferably colored with a black or gray pigment or dye. However, red, green, blue, or a mixed color thereof may be used.
[0017]
Furthermore, the microsphere-shaped transparent beads can be constituted by, for example, glass beads, plastic beads, or the like. The transparent beads preferably have a refractive index of 1.4 or more and a diameter of 100 μm or less. The refractive index is preferably 1.4 or more. When the refractive index is within this range, the incident light is sufficiently condensed and is not easily absorbed by the colored adhesive layer, and the brightness of the image light can be further increased. Because. Furthermore, the refractive index of the transparent beads is more preferably 1.55 to 1.95, and further preferably 1.60 to 1.90.
[0018]
In addition, the diameter of the microsphere-shaped transparent beads is preferably 100 μm or less. This is because when the microsphere-shaped transparent beads are densely arranged on the transparent substrate, the space area between the transparent beads is reduced, the light use efficiency is improved, and the resolution is increased. The diameter of the transparent beads is more preferably 90 μm or less, and further preferably 70 μm or less. The lower limit of the diameter of the transparent bead is regulated by the thickness at which the hot melt adhesive layer used for fixing the transparent bead and the transparent substrate can be disposed, and the diameter of the transparent bead is in the wavelength region of light. Since the scattering factor of the transmitted image light flux increases as it approaches, and the front luminance tends to decrease, it is naturally specified.
[0019]
Furthermore, it is preferable that an antireflection layer or an antiglare layer for suppressing or controlling light reflection is formed on the light emitting side surface of the transparent substrate.
[0020]
  In the method for producing a planar lens according to the present invention, on the transparent substrate,A transparent layer and a colored layer are sequentially laminated and formed.Forming a colored hot melt adhesive layer;
  A step of dispersing and arranging microspherical transparent beads on the colored hot melt adhesive layer;
  the aboveThe dispersion layer of microspherical transparent beads is pressed against the base material with a required pressing force, and the colored hot melt adhesive layer is heated to a required temperature and softened, so that the microspherical transparent beads are heated to the colored hot For melt adhesive layerA step of embedding the light-incident side of the microsphere-like transparent beads in a state where 50% or more of the diameter in the depth direction is exposed from the colored hot-melt adhesive layer;
  A step of solidifying the colored hot melt adhesive layer by lowering the temperature of the colored hot melt adhesive layer and fixing the microsphere-shaped transparent beads.It is characterized by that.
[0021]
According to the planar lens of the above-described configuration of the present invention, a planar lens with high contrast can be configured. That is, in this configuration, a large number of microspherical transparent beads are fixed to the colored hot melt adhesive layer, and these microspherical transparent beads are colored hot on the light incident side. Since it is configured to be exposed from the melt adhesive layer, incident light is efficiently incident on a large number of arranged microspherical transparent beads, and the light flux incident on the microspherical transparent beads is It is once converged and diffused by the lens action of the microspherical transparent beads.
[0022]
On the other hand, of the light incident on the planar lens, light that has not been incident on the microspherical transparent beads, that is, light that does not receive the lens action of the transparent beads is almost absorbed by the colored hot-melt adhesive layer. As a result, transmission through the front of the planar lens is prevented.
[0023]
Also, most of the external light incident from the front side of the flat lens according to the present invention, that is, the original light exit side, is absorbed by the colored hot-melt adhesive layer, so that it is observed from the front as stray light. Is effectively avoided.
[0024]
Therefore, according to the planar lens according to the present invention, the target light can be effectively derived and the contrast can be improved.
[0025]
Further, according to the above-described production method of the present invention, the microsphere-like transparent beads are fixed, and the dispersion layer of the microsphere-like transparent beads in which the dispersed arrangement of the microsphere-like transparent beads is formed on the colored hot melt adhesive layer. Then, the dispersion layer of the microspherical transparent beads is performed by heating and softening the colored hot melt adhesive layer to embed a part of the microspherical transparent beads in the colored hot melt adhesive layer. Since the melt adhesive layer is solidified and fixed, the microsphere-like transparent beads can be embedded in a predetermined depth while being surely dispersed in a predetermined density, so that they are optically uniform. In addition, a planar lens intended for mass production can be manufactured.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
1 to 5 are schematic sectional views showing embodiments of the planar lens of the present invention.
[0027]
First, a planar lens 10 shown in FIG. 1 includes a transparent base material 11, a colored hot melt adhesive layer 12 formed on the light incident side surface of the transparent base material 11, and the colored hot melt adhesive layer 12. And a large number of microspherical transparent beads 13 composed of a single layer fixed to the substrate.
[0028]
In the manufacturing method for obtaining the flat lens 10, a colored hot-melt adhesive layer 12 is formed or coated on a transparent substrate 11, and then cooled or cooled by, for example, natural cooling or forced cooling to be solidified or semi-solidified. On this, the microsphere-like transparent beads 13 are dispersedly arranged in a single layer, that is, a single particle layer arrangement. This is placed on one of the heating and pressing plates 22 by using a press device having a pair of heating and pressing plates 21 and 22 whose schematic sectional view is shown in FIG. While the colored hot melt adhesive layer 12 is melted or softened, the microspherical transparent beads 13 are pressed against the colored hot melt adhesive layer 12 with a predetermined pressure, and the microspherical transparent beads 13 are part of its diameter. That is, it is embedded in the colored hot melt adhesive layer 12 by a predetermined depth. Then, heating and pressurization by the heating and pressing plates 21 and 22 are eliminated, and the colored hot melt adhesive layer 12 is naturally cooled or forcedly cooled to room temperature to solidify the colored hot melt adhesive layer 12.
[0029]
According to this method, since the microspherical transparent beads 13 are arranged on the colored hot melt adhesive layer 12 which is applied on the substrate 11 and solidified, this arrangement is densely, that is, the maximum packing density. In this state, the colored hot-melt adhesive layer 12 is softened again, and the transparent hot beads 13 are pressed and embedded in the colored hot-melt adhesive layer 12. Therefore, the transparent beads can be embedded with a uniform arrangement density and a portion corresponding to a uniform depth, that is, a constant diameter.
[0030]
Another embodiment of the planar lens is shown in FIG. This configuration is the same as the structure shown in FIG. 1, but the colored hot melt adhesive layer 12 is formed on the transparent layer 14 on the light incident side of the transparent substrate 11, and formed on the transparent layer 14. The colored layer 15 is formed.
[0031]
Further, as another embodiment, there is a planar lens shown in FIG. This configuration is the same as the structure shown in FIG. 1 or FIG. 2, but an antireflection film 16 is formed on the exposed surface of the microspherical transparent beads 13 exposed from the colored hot melt adhesive layer 12. . The antireflection film 16 is formed by, for example, SiO 2 by vacuum deposition.₂, TiO₂, MgF₂Etc. are formed in a single layer or multiple layers. The antireflection film 16 is formed using a known technique such as coating in addition to vacuum deposition. With the configuration of the antireflection film 16, the reflection of incident light from the transparent beads 13 is suppressed, and the transmittance is improved.
[0032]
Furthermore, as another embodiment, there is a planar lens shown in FIG. This configuration is the same as the structure shown in FIG. 1 or FIG. 2, but is characterized in that the light emitting side surface of the transparent substrate 11 is an antireflection surface or an antiglare surface 17. By forming this anti-reflection or anti-glare surface 17, the regular reflection on the surface of the transparent base material 11 of disturbance light incident on the light emitting side surface of the transparent base material 11 is suppressed, and consequently the contrast of the image is avoided. can do.
[0033]
Furthermore, as another embodiment, there is a planar lens shown in FIG. This configuration is the same as the structure shown in FIG. 1 or FIG. 2, but a polarizing member, that is, a polarizing layer 18 is formed on the light emitting side surface of the transparent substrate 11. By forming the polarizing layer 18, the amount of disturbance light 20 transmitted through the planar lens can be reduced to about ½, and as a result, the contrast of the image can be increased.
[0034]
2 to 5, parts corresponding to those in FIG.
[0035]
Furthermore, as another embodiment, there is a planar lens shown in FIGS. Each of the planar lenses 10 shown in FIGS. 6 to 10 has a transparent base 11 formed of a film-like base in the configuration of FIGS. A rigid transparent substrate 41 is bonded to the surface via a transparent adhesive layer 42.
[0036]
6 to 10, portions corresponding to those in FIGS. 1 to 5 are denoted by the same reference numerals, and redundant description is omitted.
[0037]
In each configuration described above, the microsphere-shaped transparent beads 13 have a refractive index of 1.4 or more and a diameter of 100 μm or less, and expose 30% or more of the diameter of the transparent beads 13 in the colored hot melt adhesive layer 12. It is buried.
[0038]
The transparent base materials 11 and 41 applied in each embodiment are made of a transparent resin such as an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polyolefin resin, a polyester resin, or a polystyrene resin. .
[0039]
Further, the antireflection surface or antiglare surface applied to the light emitting surface of the transparent base material 11 is not particularly limited. For example, in the antireflection surface, silica is formed on the transparent base material. There is a method of forming a known antireflection film 16 such as alumina to a predetermined thickness by coating or vacuum deposition. In addition, on the antiglare surface, there are a method in which silica, plastic beads or the like are mixed in the resin, and a method in which unevenness is formed by sandblasting or embossing shaping.
[0040]
Further, the colored hot melt adhesive layer 12 or the colored layer 15 applied to each embodiment has a sufficient adhesive force to the transparent beads 13 and the transparent substrate 11. The material is hot made of acrylic resin, polycarbonate resin, polyolefin resin, polystyrene resin, polyester resin, polyurethane resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride / vinyl acetate copolymer, polyamide resin, etc. A melt adhesive is used. The colored hot-melt adhesive layer 12 or the colored layer 15 is formed by using these adhesives as a base resin and dispersing the pigment therein or dyeing with a dye.
[0041]
The colored hot melt adhesive layer 12 can be coated, for example, by a knife coater whose schematic configuration is shown in FIG. This knife coater includes an applicator roll 33 that is immersed in a heated hot-melt colored hot-melt adhesive 32 and rotates, a backup roll 34 that rolls while sandwiching the transparent substrate 11, and an application roll. It comprises a squeegee 35 that regulates the amount of adhesive 32 attached to the tal roll 33 and a doctor roll 36 that smoothes the colored hot melt adhesive layer applied on the substrate 11 by the applicator roll 33.
[0042]
The colored hot melt adhesive layer 12 can be coated by, for example, roll coating, gravure coating, kiss coating, spray coating, blade coating, rod coating, etc. in addition to the knife coating described above. Alternatively, the colored hot-melt adhesive layer 12 can be formed by using a solution obtained by dissolving and diluting a colored hot-melt adhesive in the solvent, coating the solution, and then drying the solution.
[0043]
When the colored hot melt adhesive layer 12 has a two-layer structure of the transparent layer 14 and the colored layer 15, the transparent hot melt adhesive is applied by the above-described coating methods, and then the colored hot melt adhesive is used. Is coated by a similar method.
[0044]
Furthermore, as a polarizing member for forming the polarizing layer 18 on the transparent substrate 11, for example, a polarizer obtained by adsorbing iodine or a photodichroic dye on a film such as uniaxially stretched polyvinyl alcohol or polyethylene terephthalate, Those bonded to a transparent substrate and those bonded in a state where this polarizer is sandwiched between transparent substrates are preferably used. As a transparent base material used here, for example, one or two kinds of acrylic resin, polycarbonate resin, vinyl chloride resin, polyolefin resin, polyester resin, and cellulose resin are selectively used in combination. It is done.
[0045]
When the transparent base material 11 shown in FIGS. 6 to 10 is formed into a film and the light emitting surface side is joined to the rigid substrate 41 by the transparent adhesive layer 42, the transparent adhesive is used. The layer 42 can be constituted by a transparent adhesive such as a solution type, an emulsion type, a hot melt type, a pressure-sensitive (adhesive) type, such as an acrylic resin, a polycarbonate resin, a polyolefin resin, a polystyrene resin, a polyester resin, An adhesive such as polyurethane resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyamide resin, or the like can be used.
[0046]
Next, the optical action of the planar lens according to the present invention will be described with reference to FIGS.
In FIGS. 13 and 14, a Fresnel lens 7 for making the image light 6 enter the planar lens 10 as substantially parallel light on the light incident side of the planar lens 10 according to the present invention shown in FIGS. 2 and 7, respectively. It is set as the structure arrange | positioned facing each other. 13 and FIG. 14, the same reference numerals are given to the portions corresponding to FIG. 2 and FIG. According to the planar lens 10 according to the present invention, the microsphere-like transparent beads 13 are densely arranged in one layer, that is, a single particle layer arrangement on the light incident surface side, and a part thereof is a colored hot melt adhesive layer 12. After being refracted based on the refractive index of the transparent bead 13, most of the incident light projected to the transparent bead 13 is fixed by the colored hot melt adhesive layer 12 in a state exposed from the light to the light incident side. Through the transparent base material 11 on which the colored hot melt adhesive layer 12 is formed, or through the transparent base material 11 and the substrate 41, almost all the luminous flux is diffused and emitted. On the other hand, the light 8 not incident on the transparent beads 13 is absorbed by the colored hot melt adhesive layer 12.
[0047]
Further, when an antireflection film is formed on the exposed surface of the transparent bead 11 exposed from the colored hot melt adhesive layer 12 to the light incident side, reflection of incident light can be suppressed, so that the transmittance is further increased. Can be raised.
[0048]
In addition, disturbance light 9 incident from the transparent base material 11 or the substrate 14 reaches the colored hot-melt adhesive layer 12, but most of the light is absorbed here. There is little stray light that passes through the inside of the apparatus, and the contrast of the image can be increased.
[0049]
When the colored hot melt adhesive layer 12 is colored with a black or gray pigment or dye, an image with higher contrast can be obtained.
[0050]
From the above, the viewer can see a bright and high contrast image from any angle.
【Example】
The present invention will be described in more detail based on examples.
(Example 1)
In Example 1, the planar lens 10 of FIG. 1 was produced as follows.
First, on one surface of a flat transparent substrate 11 (thickness 0.25 mm) made of polyethylene terephthalate resin, 100 parts by weight of a polyester hot melt adhesive (trade name Byron 300, manufactured by Toyobo Co., Ltd.), A colored hot melt adhesive layer 12 containing 3 parts by weight of black carbon was applied and formed by the knife coater described with reference to FIG. 12 so as to have a thickness of 10 μm after drying.
Next, fine spherical transparent beads 13 (using glass beads) having a refractive index of 1.80 and an average diameter of 55 μm are densely arranged on the colored hot-melt adhesive layer 12, and the press described in FIG. The temperature is 130 ° C and the pressure is 4 kg / cm by hot pressing with the equipment.²Then, the beads were embedded by cooling to room temperature. The thickness of the colored hot melt adhesive layer 12 after embedding the transparent beads 13 was 20 μm. Further, 64% of the diameter of the transparent bead 13 was exposed in the direction of embedding depth.
[0051]
In place of the lenticular lens 5 shown in FIG. 16 constituting the transmissive screen 2 used in the rear projection display device shown in FIG. 15, the planar lens 10 according to Example 1 was attached and the projected image was observed. However, a viewing angle of 1.5 times in the horizontal direction and 10 times in the vertical direction was obtained as compared with the screen using the conventional lenticular lens 5. In addition, high-quality images with high contrast and good resolution could be observed.
[0052]
(Example 2)
In Example 2, the planar lens 10 shown in FIG. 2 was produced as follows.
First, on one surface of a flat transparent substrate 11 (thickness 0.25 mm) made of polyethylene terephthalate resin, a transparent layer 14 made of a polyester hot melt adhesive (trade name Byron 560, manufactured by Toyobo Co., Ltd.) After drying, it was applied with the knife coater described in FIG. 12 so as to be 14 μm, and further 3 parts by weight of black carbon with respect to 100 parts by weight of a polyester-based hot melt adhesive (trade name Byron 300, manufactured by Toyobo Co., Ltd.). The blended colored layer 15 was applied by a similar knife coater so as to have a thickness of 10 μm after drying to form a colored hot melt adhesive layer 12 composed of the transparent layer 14 and the colored layer 15. Next, microspherical transparent beads 13 (using glass beads) having a refractive index of 1.80 and an average diameter of 55 μm are densely arranged on the colored hot-melt adhesive layer 12 and subjected to hot pressing in FIG. , Temperature 130 ° C, pressure 4kg / cm²Then, the beads 13 were embedded by cooling to room temperature. The thickness of the colored hot melt adhesive layer 12 after embedding the beads was 20 μm. Further, 64% of the diameter of the beads 13 was exposed in the burying depth direction.
[0053]
When the lenticular lens 5 shown in FIG. 16 constituting the transmissive screen 2 used in the rear projection display device shown in FIG. 15 is replaced with the planar lens 10 according to the second embodiment, the projected image is observed. As compared with the screen using the conventional lenticular lens 5, a viewing angle of 1.5 times in the horizontal direction and 10 times in the vertical direction was obtained. In addition, high-quality images with high contrast and good resolution could be observed.
[0054]
(Example 3)
In Example 3, the planar lens 10 shown in FIG. 3 was produced as follows.
First, on the exposed surface of the microspherical transparent beads 13 of the planar lens 10 obtained in the same manner as in Example 2, SiO 2 is used by vacuum deposition.₂The antireflection film 16 made of was formed to a thickness of 100 nm. Due to the configuration of the antireflection film 16, the bead 13 had 64% of its diameter exposed in the direction of burying depth.
[0055]
In place of the lenticular lens 5 shown in FIG. 16 constituting the transmissive screen 2 used in the rear projection display device shown in FIG. 15, the planar lens 10 according to this Example 3 was attached and the projected image was observed. However, as in Example 2, the viewing angle was 1.5 times in the horizontal direction and 10 times in the vertical direction compared to the screen using the conventional lenticular lens 5. Further, the brightness of the image was improved as compared with Example 2, and a high-quality image with good contrast and resolution could be observed.
[0056]
(Example 4)
In Example 4, the planar lens 10 shown in FIG. 4 was produced as follows.
First, the surface of the transparent substrate 11 of the flat lens obtained in the same manner as in Example 2 is irradiated with SiO 2 by vacuum deposition on the image light emitting side surface.₂An antireflection film 17 made of a film having a thickness of 100 nm was formed. Due to the configuration of the antireflection film 17, 64% of the diameter of the beads was exposed in the direction of the embedding depth.
[0057]
In place of the lenticular lens 5 shown in FIG. 16 constituting the transmissive screen 2 used in the rear projection display device shown in FIG. 15, the planar lens 10 according to this Example 4 was attached and the projected image was observed. However, as in Example 2, the viewing angle was 1.5 times in the horizontal direction and 10 times in the vertical direction compared to the screen using the conventional lenticular lens 5. Further, the contrast was further improved as compared with Example 2, and no high-quality image with good resolution could be observed without any harmful effects caused by ambient light.
[0058]
(Example 5)
In Example 5, the planar lens 10 shown in FIG. 5 was produced as follows.
First, a polarizing film (manufactured by Nitto Denko Corporation, trade name NPF-G1225Du) is an acrylic pressure-sensitive adhesive on the surface of the transparent substrate 11 of the flat lens obtained in the same manner as in Example 2 on the image light exit side. The polarizing layer 18 was formed by sticking using
[0059]
In place of the lenticular lens 5 shown in FIG. 16 that constitutes the transmissive screen 2 used in the rear projection display device shown in FIG. 15, the planar lens 10 according to this example 5 is changed in the polarization direction of the emitted light and the polarizing film. When the projection image was observed with the transmission axes substantially matched with each other, the horizontal direction was 1.5 times that in the vertical direction as compared with the screen using the conventional lenticular lens 34, as in Example 2. A viewing angle of 10 times was obtained. Further, the contrast was further improved as compared with Example 2, and there were few harmful effects due to ambient light, and a high-quality image with good resolution could be observed.
[0060]
(Example 6)
A planar lens was produced in the same manner as in Example 1 except that the thickness of the colored hot-melt adhesive layer 12 was changed to 30 μm after drying. The thickness of the colored hot-melt adhesive layer 12 after completion was 40 μm. Further, 27% of the diameter of the microsphere-shaped transparent beads 13 was exposed from the colored adhesive layer 12.
[0061]
When the flat lens 10 according to Example 6 is attached instead of the lenticular lens 5 shown in FIG. 16 constituting the transmissive screen 2 used in the rear projection display device shown in FIG. 15, the image is observed. As compared with a screen using the conventional lenticular lens 5, a viewing angle of 1.5 times in the horizontal direction and 10 times in the vertical direction was obtained. A high quality image with good contrast and resolution could be observed. Also, the luminance was higher than that of the screen using the conventional lenticular lens 5 (however, it was slightly lower than that of Example 1).
[0062]
(Example 7)
A planar lens 10 was produced in the same manner as in Example 1 except that, as the microsphere-shaped transparent beads 13, polymethyl methacrylate beads having a refractive index of 1.49 and a diameter of 50 μm were used instead of glass beads.
[0063]
The thickness of the colored hot melt adhesive layer 12 after completion was 20 μm. Further, 60% of the diameter of the beads 13 was exposed from the colored hot melt adhesive layer 12.
[0064]
In place of the lenticular lens 5 shown in FIG. 16 constituting the transmissive screen 2 used in the rear projection display device shown in FIG. 15, the planar lens 10 according to the present example was mounted and the image was observed. Compared with a screen using a conventional lenticular lens 5, a viewing angle of 1.2 times in the horizontal direction and 8 times in the vertical direction was obtained. A high quality image with good contrast and resolution could be observed.
[0065]
(Example 8)
A film-like transparent substrate 11 in which microsphere-like transparent beads 13 are closely arranged and fixed by the colored hot-melt adhesive layer 12 by the same method and configuration as in Example 1 is formed to a thickness of 50 μm as shown in FIG. A substrate 41 made of acrylic resin having a thickness of 2 mm to which an acrylic adhesive layer 42 was applied was bonded to the side opposite to the side having the microspherical transparent beads 13. In this way, a transmission screen having practical strength was produced.
[0066]
The screen thus formed was able to obtain the same optical characteristics as described in Example 1, that is, horizontal and vertical viewing angles and contrast.
Example 9
A film-like transparent base material 11 in which microsphere-like transparent beads 13 are closely arranged and fixed by a colored hot-melt adhesive layer 12 comprising a transparent layer 14 and a colored layer 15 by the same method and configuration as in Example 2 is shown in FIG. As shown in FIG. 5, the substrate 41 having rigidity of 2 mm thick and coated with an acrylic adhesive layer 42 having a thickness of 50 μm was bonded to the side opposite to the side having the microspherical transparent beads 13. In this way, a transmission screen having practical strength was produced.
[0067]
The screen thus formed was able to obtain the same optical characteristics as described in Example 2, ie, horizontal and vertical viewing angles and contrast.
(Example 10)
The microsphere-like transparent beads 13 are closely arranged and fixed by the colored hot melt adhesive layer 12 composed of the transparent layer 14 and the colored layer 15 by the same method and configuration as in Example 3, and the transparent beads 13 on the light incident side are fixed. As shown in FIG. 8, the transparent substrate 11 having the antireflection film 16 formed on the exposed portion is a rigid substrate made of acrylic resin having a thickness of 2 mm and an acrylic adhesive layer 42 applied to the thickness of 50 μm. 41 was joined to the side opposite to the side having the microsphere-shaped transparent beads 13. In this way, a transmission screen having practical strength was produced.
[0068]
The screen thus formed was able to obtain the same optical characteristics as described in Example 3, that is, horizontal and vertical viewing angles and contrast.
[0069]
(Example 11)
As shown in FIG. 9, an antireflection film 17 similar to that in Example 4 is formed on one surface, and an acrylic resin having a thickness of 2 mm in which an acrylic transparent adhesive layer 42 is applied on the other surface to a thickness of 50 μm. A transparent substrate 41 having rigidity was prepared. Then, on the side of the transparent substrate 41 having the transparent adhesive layer 42, a microspherical transparent is formed on the colored hot-melt adhesive layer 12 composed of the transparent layer 14 and the colored layer 15 by the same method and configuration as in Example 4. The film-like transparent base material 11 to which the beads 13 were closely arranged and fixed was joined on the side opposite to the side having the microsphere-like transparent beads 13 to produce a transmission screen having practical strength.
[0070]
The screen thus formed was able to obtain the same optical characteristics as described in Example 4, ie, horizontal and vertical viewing angles and contrast.
[0071]
(Example 12)
As shown in FIG. 10, a polarizing layer 18 similar to that in Example 5 is formed on one surface, and an acrylic resin having a thickness of 2 mm, in which an acrylic transparent adhesive layer 42 is applied on the other surface to a thickness of 50 μm. A transparent substrate 41 having the following rigidity was prepared. Then, on the side of the transparent substrate 41 having the transparent adhesive layer 42, the colored hot melt adhesive layer 12 composed of the transparent layer 14 and the colored layer 15 is transparent in the form of microspheres by the same method and configuration as in Example 5. The film-like transparent base material 11 to which the beads 13 were closely arranged and fixed was joined on the side opposite to the side having the microsphere-like transparent beads 13 to produce a transmission screen having practical strength.
[0072]
The screen thus formed was able to obtain the same optical characteristics as described in Example 5, that is, horizontal and vertical viewing angles and contrast.
[0073]
As described above, the planar lens according to the present invention can increase the viewing angle not only in the horizontal direction but also in the vertical direction. For example, the planar lens can be applied to a transmissive screen used in a rear projection display device. A high-quality image with good resolution can be observed.
[0074]
In the planar lens according to the present invention, the microsphere-like transparent beads 13 are fixed by the colored hot-melt adhesive layer 12, so that the transparent beads 13 are uniformly dispersed and the amount of burying is set. Therefore, it is possible to easily produce a planar lens having stable and uniform characteristics.
[0075]
In the above example, the case where the planar lens according to the present invention is applied to a transmissive screen has been mainly described. However, the viewing angle widening plate of a liquid crystal display device, a plasma display device, an electroluminescence display device, etc., or a liquid crystal backlight. It can be used for a light diffusing plate for diffusing light from various illumination light sources.
[0076]
【The invention's effect】
As described above, according to the planar lens of the configuration of the present invention, it is possible to improve the generation of moire interference fringes and to configure a planar lens with high contrast. That is, in this configuration, a large number of microspherical transparent beads are fixed to the colored hot melt adhesive layer, and these microspherical transparent beads are colored hot on the light incident side. Since it is configured to be exposed from the melt adhesive layer, incident light is efficiently incident on a large number of arranged microspherical transparent beads, and the light flux incident on the microspherical transparent beads is Since it is once converged by the lens action of the microsphere-like transparent beads and diffused in the horizontal and vertical directions, that is, in three dimensions, the generation of moire interference fringes can be improved, and the viewing angle in both the horizontal and vertical directions can be increased. it can.
[0077]
On the other hand, of the incident light to the planar lens, light that is not incident on the microspherical transparent beads 13 and is not subjected to the lens action by the transparent beads 13 is almost absorbed by the colored hot melt adhesive layer 12. Thus, it is prevented from transmitting to the front of the planar lens.
[0078]
Also, most of the external light incident from the front side of the flat lens 10 according to the present invention, that is, the original light exit side, is absorbed by the colored hot-melt adhesive layer 12 and thus is observed as stray light from the front side. Is effectively avoided.
[0079]
Therefore, the flat lens according to the present invention has a wide viewing angle when viewed from any direction, and can improve the contrast without reducing the luminance of the image.
[0080]
Further, according to the above-described production method of the present invention, the microsphere-shaped transparent beads 13 are fixed to the dispersion layer of the microsphere-shaped transparent beads in which the dispersed arrangement of the microsphere-shaped transparent beads is formed on the colored hot melt adhesive layer 12. After that, the dispersion layer of the microspherical transparent beads is performed by heating and softening the colored hot melt adhesive layer to embed a part of the microspherical transparent beads in the colored hot melt adhesive layer, Since the colored hot melt adhesive layer is solidified and fixed, the microsphere-like transparent beads can be reliably dispersed in a predetermined density and embedded in a predetermined depth optically. It is possible to produce a flat lens that is uniformly and mass-produced.
[0081]
Further, when an antireflection film is formed on the exposed surface of the transparent beads, the reflection of incident light can be suppressed, so that the transmittance can be further increased.
[0082]
Further, in the case where the light emission side surface of the transparent substrate is subjected to antireflection treatment or antiglare treatment, the specular reflection of disturbance light is suppressed, and the image incident on the planar lens 10 is converted into the light emission side. Therefore, the image can be observed without reducing the contrast.
[0083]
In addition, when the polarizing layer 18 is provided on the light emitting side surface of the transparent base material 11 or the transparent substrate 41 bonded to the light emitting side surface, about 1/2 of the disturbance light is absorbed. The contrast is not lowered.
[0084]
Therefore, according to the present invention, a high-quality image can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 2 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 3 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 4 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 5 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 6 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 7 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 8 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 9 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 10 is a schematic cross-sectional view showing an embodiment of a planar lens of the present invention.
FIG. 11 is a schematic cross-sectional view of an example of a press apparatus used in the method for manufacturing a planar lens according to the present invention.
FIG. 12 is a schematic cross-sectional view of an example of a coating apparatus for a colored hot melt adhesive layer used in the method for producing a planar lens according to the present invention.
FIG. 13 is a schematic cross-sectional view showing the optical action of an embodiment of the planar lens of the present invention.
FIG. 14 is a schematic cross-sectional view showing the optical action of an embodiment of the planar lens of the present invention.
FIG. 15 is a schematic configuration diagram of a general rear projection display device to which a planar lens is applied.
FIG. 16 is a schematic cross-sectional view showing the structure of a conventional planar lens.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Projection optical system, 2 Transmission type screen, 3 Mirror, 4,7 Fresnel lens, 5 Lenticular lens, 6 Image light, 9 Disturbance light, 10 Plane type lens, 11 Transparent base material, 12 Colored hot melt adhesive layer, 13 Microsphere-like transparent beads, 14 transparent layers, 15 colored layers, 16, 17 antireflection film, 18 polarizing layer, 41 substrate

Claims (9)

A transparent substrate;
A colored hot melt adhesive layer formed on the light incident side surface of this transparent substrate,
Having a large number of microspherical transparent beads consisting of one layer embedded and fixed in this colored hot melt adhesive layer ,
The colored hot melt adhesive layer is composed of a transparent layer disposed on the transparent substrate side and a colored layer formed on the light incident side thereon, and the microsphere-shaped transparent beads are incident on the light incident surface. A flat lens having a structure in which 50% or more of the diameter in the depth direction on the side is exposed and embedded from the colored hot melt adhesive layer .   2. The flat surface according to claim 1, wherein the transparent base material is a film-like base material, and a rigid transparent substrate is bonded to the light emitting side surface of the transparent base material via a transparent adhesive. Type lens. 3. The planar lens according to claim 1 , wherein the colored layer of the colored hot melt adhesive is colored black or gray . 4. The planar lens according to claim 1, wherein the microsphere-like transparent beads have a refractive index of 1.4 or more and a diameter of 100 μm or less . The flat lens according to claim 1, 2, 3, or 4 , wherein the microsphere-shaped transparent beads are made of glass beads . 6. The planar lens according to claim 1, wherein the light-exiting surface of the transparent substrate or the rigid transparent substrate is an antireflection surface or an antiglare surface . The antireflection film which suppresses reflection of the said incident light is formed in the exposed surface exposed to the light-incidence side from the said colored hot-melt-adhesive adhesive layer of the said microsphere-like transparent bead, The 1st aspect is characterized by the above-mentioned. The planar lens according to 2, 3, 4, 5 or 6. 8. The planar lens according to claim 1 , wherein a polarizing member is provided on a light emitting side surface of the transparent substrate or the rigid transparent substrate. . A step of forming a colored hot melt adhesive layer on the transparent substrate, in which a transparent layer and a colored layer are sequentially laminated and formed,
Dispersing and arranging microspherical transparent beads on the colored hot melt adhesive layer;
The dispersion layer of the microspherical transparent beads is pressed against the substrate with a required pressing force, the colored hot melt adhesive layer is heated to a required temperature and softened, and the microspherical transparent beads are heated to the colored hot Embedded in the melt adhesive layer in a state where the light incident side of the microsphere-like transparent beads is exposed from the colored hot melt adhesive layer by 50% or more of the diameter in the depth direction;
A method for producing a planar lens, comprising: solidifying the colored hot-melt adhesive layer by lowering the temperature of the colored hot-melt adhesive layer and fixing the microspherical transparent beads. "

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