JP2006231917A - Lens sheet production method - Google Patents

Abstract

The present invention provides a method for producing a lens sheet comprising a glass substrate and a resin lens layer having a plurality of projections and depressions that are directly molded on the glass substrate.
A female mold production process for producing a flexible female mold for molding a lens layer, a filling process for filling a resin for a lens layer between the female mold and a glass substrate, and a lens layer Curing process to cure the resin, one end of the female mold is bent in the direction to separate the female mold and the glass substrate, and then the female mold is bent to the other end of the female mold, thereby separating the female mold and the lens. And a peeling step.
[Selection] Figure 11

Description

  The present invention relates to a method for manufacturing a lens sheet having a plurality of irregularities on one surface.

When the lens sheet such as a Fresnel lens and a fly-eye lens is insufficient in rigidity of the entire sheet, local contact with other members due to deflection occurs, and the lens surface is scratched or damaged. Therefore, in order to improve the rigidity of the entire sheet, a proposal has been made to use a glass substrate as the base material of the sheet (see, for example, Patent Document 1).
JP-A-4-242703

  However, when a lens is directly molded on a glass substrate using the conventional technique, the glass substrate hardly bends during mold release. Accordingly, there is a problem in that the adsorption force between the lens and the mold at the time of mold release is greatly increased as compared with the case of using a resin substrate, and problems such as breakage of the glass substrate occur at the time of mold release.

  In order to solve the above-mentioned problems, in the first embodiment of the present invention, a method for producing a lens sheet comprising a glass substrate and a resin lens layer having a plurality of projections and depressions that are directly molded on the glass substrate. A female mold production process for producing a flexible female mold for molding a lens layer, a filling process for filling a resin for the lens layer between the female mold and the glass substrate, and a lens layer Curing process to cure the resin, one end of the female mold is bent in the direction to separate the female mold and the glass substrate, and then the female mold is bent to the other end of the female mold, thereby separating the female mold and the lens. A method for producing a lens sheet is provided. Thereby, the force required for peeling between the female mold and the lens layer can be greatly reduced. Therefore, a large lens sheet having a glass substrate can be easily produced.

  In the above production method, the female mold may be formed using bis (2-) oxazoline or phenoxy resin as a main component. Thereby, the durability of the female mold is ensured, and the female mold can be used repeatedly.

  Prior to the filling step, the production method may further include a substrate processing step of coating a surface of the glass substrate on which the lens layer is formed with a silane coupling agent. Thereby, the adhesive strength between the glass substrate and the lens layer can be improved.

  In the above production method, the filling step may be performed in a state where the surroundings are decompressed. Thereby, the resin for the lens layer can be filled in every corner of the female mold.

  In the production method described above, a female die having a shape restoring property that is restored to the shape in the filling step after being bent in the peeling step may be used as the flexible female die. Thereby, since a lens layer can be repeatedly shape | molded with a female type | mold, production cost can be reduced.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 shows a configuration of a rear projection display 800 which is an embodiment of a lens sheet. The rear projection display 800 includes an optical engine 700, a mirror 600, and a screen 500. The optical image output from the optical engine 700 is reflected by the mirror 600 and enters the screen 500. The screen 500 realizes an appropriate observation region by diffusing the incident optical image and emitting it to the viewer side.

  FIG. 2 shows a detailed configuration of part A in the screen 500 of FIG. The screen 500 includes a Fresnel lens 200, a lenticular lens 100, and a front plate 300 in close proximity to or in close contact with each other. The Fresnel lens 200 has a plurality of prisms 20 and aligns the traveling direction of light emitted from the optical engine 700 in a direction substantially perpendicular to the screen 500 by the prisms 20. The lenticular lens 100 includes a plurality of lumpy single lenses 10, and diffuses incident light by the single lens 10 and emits it. The front plate 300 protects the fly-eye lens 100 and reduces reflection of external light by anti-glare (AG) processing or anti-reflection (AR) processing applied to the surface. The prism 20 and the single lens 10 are an example of a plurality of irregularities in the lens layer. The lenticular lens 100 may be a fly-eye lens.

  The lenticular lens 100 and the Fresnel lens 200 are examples of a lens sheet in the present invention. The prism 20 and the single lens 10 are an example of a plurality of irregularities in the lens layer. The lens sheet may be a fly-eye lens sheet including a plurality of dome-shaped single lenses. In this case, the plurality of dome-shaped single lenses is an example of the plurality of irregularities in the lens layer of the present invention. Hereinafter, this embodiment will be described using the Fresnel lens 200 as an example of the lens sheet of the present invention.

  The holding member 400 holds the edge portions of the Fresnel lens 200, the lenticular lens 100, and the front plate 300 with the prism 20 and the single lens 10 facing each other. For example, the holding member 400 is provided at four positions on the periphery of the screen 500 in the vertical and horizontal directions. The holding member 400 is formed of, for example, a metal or resin having a spring property.

  FIG. 3 shows a plan view of the Fresnel lens 200. FIG. 4 shows a cross-sectional view of the Fresnel lens 200. In the Fresnel lens 200, the prisms 20 are arranged concentrically without gaps. Further, the outer shape of the Fresnel lens 200 is formed with an aspect ratio corresponding to the application of the screen 500. For example, when used in the application of the rear projection display 800, the ratio of the horizontal direction to the vertical direction in FIG. 3 is about 16: 9. Another example of the ratio between the horizontal direction and the vertical direction is about 4: 3. Further, the height of the prism 20 constituting the Fresnel lens 200 is formed so as to go outward as shown in FIG.

  FIG. 5 is a cross-sectional view showing an example of the configuration of the Fresnel lens 200. The Fresnel lens 200 includes a glass substrate 24 and a lens layer 26. The lens layer 26 of this embodiment is an ultraviolet curable transparent urethane acrylate resin (2P resin). The glass substrate 24 is a transparent plate glass. The glass substrate 24 is formed with a thickness that ensures the strength required for the Fresnel lens 200. For example, the larger the area of the Fresnel lens 200, the thicker the glass substrate 24 becomes. The lens layer 26 is formed integrally with the glass substrate 24 on one side of the glass substrate 24.

  6 to 11 show an embodiment of a production method of the Fresnel lens 200. FIG. The production method of the Fresnel lens 200 in the present embodiment includes a female mold manufacturing process for manufacturing the flexible female mold 30, a filling process for filling the lens resin 21 between the female mold 30 and the glass substrate 24, and a lens. A curing process for curing the resin 21 and a peeling process for peeling the female mold 30.

  6 and 7 show the female mold manufacturing process of this embodiment. First, a male mold 70 having an uneven shape similar to the lens surface of the Fresnel lens 200 is prepared, and an uncured mold resin 23 is poured into the male mold 70 using a dispenser 40. The male mold 70 is made of, for example, silicon rubber. The male mold 70 can be manufactured by casting silicon rubber onto a master mold (for example, a mold or the like) manufactured by a known method such as a cutting method or a laser processing method. The male mold 70 has a damming portion 74 that is higher than the concavo-convex shape around the concavo-convex shape of the Fresnel lens 200. The male mold 70 further has a flow stop forming protrusion 72 that is higher than the irregularities of the Fresnel lens 200 and lower than the damming portion 74. In this step, the uncured mold resin 23 is filled in every corner of the lens surface of the Fresnel lens 200 inside the damming portion 74.

  The mold resin 23 is made of a material whose main component is bis (2-) oxazoline or phenoxy resin. When the uncured mold resin 23 is filled in the male mold 70, it is desirable to carry out the inside of a vacuum chamber that is depressurized in order to prevent air entrapment. Further, in order to make the upper surface of the mold resin 23 filled in the male mold 70 parallel to the reference plane of the male mold 70, for example, the lower surface of the male mold 70 shown in FIG. 6, the uncured state filled in the male mold 70. The upper surface of the mold resin 23 may be pressed with a plate parallel to the reference plane of the male mold 70.

  Next, the mold resin 23 is cured while being filled in the male mold 70. The mold resin 23 becomes the female mold 30 by being cured in the male mold 70. The female die 30 is flexible even in a cured state. Therefore, as shown in FIG. 7, one end of the female mold 30 is bent in the direction in which the female mold 30 is peeled from the male mold 70, and then the female mold 30 is bent to the other end, thereby making the female mold 30 a male mold. Peel from 70.

Hereinafter, one example of each of the female mold manufacturing steps in the case where bis (2-) oxazoline is the main component and the phenoxy resin is the main component as the mold resin 23 will be described. First, the material composition when bis (2-) oxazoline is the main component as the mold resin 23 is as follows.
a) 2,2 ′-(1,3-phenylene) bis (2-) oxazoline: 291.6 parts by weight b) Diamine (2-trimer): 198 parts by weight c) Dicarboxylic acid: 56.4 parts by weight d) Bisphenol F type epoxy resin (epoxy equivalent 170-180): 340 parts by weight e) Catalyst (1,4-dibromobutane): 1 part by weight

  First, a), b) and c) are mixed and pre-reacted at 120 ° C. for 1 hour. Thereafter, d) and e) are further mixed and filled into the male mold 70, and this reaction is performed. The conditions for this reaction are first at 80 ° C. for 8 hours, then at 120 ° C. for 3 hours (step cure), and finally at 140 ° C. for 3 hours (after cure).

Next, the material composition when the main component of the mold resin 23 is a phenoxy resin is as follows.
p) Bisphenol F: 55 parts by weight q) Bisphenol F type epoxy resin: 100 parts by weight r) Triphenylphosphine: 2.0 parts by weight

The mixing method is as follows. First, p), q) and r) are mixed and dissolved to obtain a resin composition. Then, the resin composition is cured under the following curing conditions (step cure).
1) 90 ° C. × 6 hours 2) 120 ° C. × 4 hours The above blending examples, reaction conditions, and curing conditions are only examples.

  8 and 9 show a filling process for filling the lens resin 21 between the female mold 30 and the glass substrate 24. First, the female mold 30 molded by the female mold manufacturing process is placed on a flat surface plate 60 with the cavity side on which the inverted shape of the lens layer 26 is formed facing upward. Since the female mold 30 has flexibility, the flatness of the female mold 30 is ensured by placing it on the flat surface plate 60. Next, as shown in FIG. 8, the uncured lens resin 21 is filled into the entire cavity of the female mold 30 using the dispenser 40. The lens resin 21 is a transparent ultraviolet curable resin such as a urethane acrylate resin. The uncured lens resin 21 in the present embodiment is in a viscous fluid state having a high viscosity.

  Next, the glass substrate 24 is prepared. One side of the glass substrate 24 is coated with a silane coupling agent for the purpose of improving the adhesion strength with the lens layer 26. For example, a silane coupling agent is applied to the glass substrate 24, and a predetermined heat treatment is performed on the glass substrate 24 to which the silane coupling agent is applied. After the heat treatment, the excess silane coupling agent is washed away with a solvent such as water. Thereby, the coating nonuniformity of a silane coupling agent can be improved. By coating the glass substrate 24 with a silane coupling agent, the adhesion strength between the glass substrate 24 that is an inorganic material and the lens layer 26 that is an organic material is improved.

  Next, the surface of the glass substrate 24 on which the silane coupling agent is coded is brought into close contact with the uncured lens resin 21 (FIG. 9). Then, the glass substrate 24 is pressed against the female mold 30. For example, the upper surface of the glass substrate 24 is pressurized so that the distance from the upper surface of the female mold 30 to the upper surface of the glass substrate 24 is the distance from the valley of the prism 20 in the Fresnel lens 200 to the back surface of the glass substrate 24. The step of pressurizing the upper surface of the glass substrate 24 shown in FIG. 9 is performed inside a vacuum chamber in which the periphery of the female mold 30 is decompressed. Accordingly, the lens resin 21 does not embed bubbles, and the entire cavity of the lens layer 26 in the female mold 30 is reliably filled. Further, a flow stop 32 formed by a flow stop forming protrusion 72 of the male mold 70 is formed outside the cavity of the lens layer 26 in the female mold 30. The flow stop 32 receives the excess lens resin 21 that protrudes from the range of the glass substrate 24.

  FIG. 10 shows the curing process of this example. The curing process is performed under atmospheric pressure. In the curing step, the lens resin 21 is cured by irradiating ultraviolet rays from the glass substrate 24 side. An ultraviolet lamp 44 is used for ultraviolet irradiation. The ultraviolet lamp 44 is caused to emit light for a time sufficient to cure the lens resin 21 from above the glass substrate 24. After irradiation with ultraviolet rays, the inside of the vacuum chamber is returned to atmospheric pressure. The lens resin 21 becomes the lens layer 26 after curing.

  FIG. 11 shows the peeling process of a present Example. In the peeling step, the female mold 30 is peeled from the glass substrate 24 and the lens layer 26. First, the female mold 30, the lens layer 26, and the glass substrate 24 that have undergone the curing process are turned upside down from the state shown in FIG. That is, the glass substrate 24 is placed on the lower surface and the female mold 30 is placed on the upper surface. Next, one end of the female mold 30 is bent in a direction in which the female mold 30 and the glass substrate 24 are separated from each other, that is, upward, and then the female mold 30 is pulled up to the other end of the female mold 30 while being bent. In this way, the female mold 30 is peeled from the lens layer 26. After peeling, the range used for the screen 500 is cut out to complete the Fresnel lens 200. The flexible female die 30 desirably has a shape restoring property that restores the shape of the female die 30 in the filling step within a predetermined time after the peeling step. Thereby, since a lens layer can be repeatedly shape | molded with a female type | mold, production cost can be reduced.

12 and 13 are conceptual diagrams showing a method of testing the shape restoring property of the resin female mold 30. FIG. Hereinafter, the shape recoverability of the female mold 30 of this embodiment will be compared with the electroforming mold 31 which is an example of a conventional metal female mold. The electroforming mold 31 is, for example, a nickel electroforming mold. Test pieces having the following dimensions are prepared for the female mold 30 and the electroforming mold 31.
Female mold 30: width 20 mm, length 200 mm, thickness 2.3 mm and 3.7 mm (2 types)
Electric mold 31: width 20 mm, length 200 mm, thickness 0.5 mm and 2.0 mm (two types)

  Next, as shown in FIG. 12, the test pieces of the female mold 30 and the electroforming mold 31 are placed on the upper surface of a cylindrical bending test jig 90 having a predetermined curvature R. In this case, the test piece is placed so that the cylinder axis of the bending test jig 90 and the longitudinal direction of the test piece are orthogonal to each other. And as shown in FIG. 13, the load which is a grade which a test piece bends along the jig | tool 90 for bending tests is repeatedly applied to the both ends of a test piece. The cycle of the repeated load is about 1 Hz. Immediately after applying a predetermined number of repeated loads, the amount of warpage remaining on the test piece is measured. The amount of warpage is measured by measuring the amount of floating near the center of the test piece in the longitudinal direction with the test piece placed on a horizontal table such as a surface plate.

  Table 1 below shows the amount of warping of the test piece after bending a predetermined number of times. In the table, “-” indicates a state where the test cannot be continued.

  As is clear from Table 1, when the test piece thickness is 2 mm, the electroforming mold 31 warps 6.0 mm or more by one bending in any of R: 160 mm and R: 240 mm. Further, when the specimen thickness is 0.5 mm and R is 160 mm, a warp of 3.0 mm occurs after bending 10 times or more, and when the specimen thickness is 0.5 mm and R is 240 mm, 5 times. A warp of 1.0 mm was generated by the above bending.

  On the other hand, in the case of the test piece thickness: 3.7 mm and R: 160, the female die 30 of this embodiment has a warpage of 0.3 mm after bending 50 times and a curvature of 0.8 mm after bending 100 times. occured. When the specimen thickness was 2.3 mm, warpage of 0.3 mm occurred after 100 times of bending in both cases of R: 160 mm and R: 240 mm. The warpage of the female mold 30 disappeared when left for 5 minutes. As is clear from the above test results, the shape restoration property of the female mold 30 of this embodiment is significantly improved as compared with the conventional electroforming mold 31. Furthermore, since the shape is restored even if it is repeatedly bent, the female mold 30 can be used repeatedly when producing a lens sheet having a glass substrate.

  As is apparent from the above description, according to the present embodiment, in the peeling process, the female mold 30 and the lens layer 26 can be gradually peeled while the female mold 30 is bent. Therefore, compared to the conventional production method in which the glass substrate 24 and the female die 30 are peeled in a parallel state, the load required for peeling the female die 30 and the lens layer 26 can be greatly reduced. Therefore, even a large lens sheet having a glass substrate can be easily produced without damaging the glass substrate 24. Further, since the female mold 30 can be used repeatedly, the lens sheet can be produced at low cost.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

It is a figure which shows the structure of the rear projection display 800 which concerns on this embodiment. It is the A section enlarged view of the screen 500 shown in FIG. 2 is a plan view of a Fresnel lens 200. FIG. FIG. 3 is a cross-sectional view of a Fresnel lens 200. 2 is a partial cross-sectional view showing an example of the configuration of a Fresnel lens 200. FIG. 5 is a diagram illustrating an example of a production process of the Fresnel lens 200. FIG. 5 is a diagram illustrating an example of a production process of the Fresnel lens 200. FIG. 5 is a diagram illustrating an example of a production process of the Fresnel lens 200. FIG. 5 is a diagram illustrating an example of a production process of the Fresnel lens 200. FIG. 5 is a diagram illustrating an example of a production process of the Fresnel lens 200. FIG. 5 is a diagram illustrating an example of a production process of the Fresnel lens 200. FIG. It is a conceptual diagram which shows the method of testing the shape restoring property of the female type | mold 30. FIG. It is a conceptual diagram which shows the method of testing the shape restoring property of the female type | mold 30. FIG.

Explanation of symbols

10 single lens, 20 prism, 21 lens resin, 23 mold resin, 24 glass substrate, 26 lens layer, 30 female mold, 31 electroforming mold, 32 flow stop, 40 dispenser, 44 ultraviolet lamp, 46 glass plate, 60 fixed Panel, 70 Male, 72 Flow stop forming projection, 90 Bending test jig, 100 Fly eye lens, 200 Fresnel lens, 300 Front plate, 400 Holding member, 500 Screen, 600 Mirror, 700 Optical engine, 800 Rear projection display

Claims (5)

A method for producing a lens sheet comprising a glass substrate and a resin lens layer having a plurality of irregularities, which is directly molded on the glass substrate,
A female mold production process for producing a flexible female mold for molding the lens layer;
A filling step of filling the lens layer resin between the female mold and the glass substrate;
A curing step of curing the resin for the lens layer;
The female mold and the lens are peeled by bending one end of the female mold in a direction in which the female mold and the glass substrate are separated from each other, and subsequently bending the female mold to the other end of the female mold. A method for producing a lens sheet comprising a peeling step.   The method for producing a lens sheet according to claim 1, wherein the female mold is formed using bis (2-) oxazoline or phenoxy resin as a main component.   The method for producing a lens sheet according to claim 1, further comprising a substrate treatment step of coating a surface of the glass substrate on which the lens layer is formed with a silane coupling agent prior to the filling step.   The lens sheet production method according to claim 1, wherein the filling step is performed in a state where the surroundings are decompressed.   The method for producing a lens sheet according to claim 1, wherein a female die having a shape restoring property that is restored to the shape in the filling step after being subjected to the bending in the peeling step is used as the flexible female die.

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