JP2009186644A - Method for manufacturing light guide panel, and surface light source device equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a light guide panel at high yield, by suppressing a defect in protrusions, when manufacturing the light guide panel having the plurality of protrusions. <P>SOLUTION: This method for manufacturing the light guide panel having a light guide panel body having a light incident face on which at least a light emitted from a primary light source is made incident, a light exit face from which the guided light exits, a light reflecting face on a side opposite to the light exit face, and a plurality of protrusions on the light exit face. The method includes steps of: (1) forming the plurality of protrusions and the light guide panel body by curing a curable resin using a mold having recesses corresponding to the protrusions, and (2) releasing the formed protrusions and light guide panel body from the mold, in this order. An elastic modulus of the protrusion is higher than that of the mold in the releasing process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a light guide plate. More specifically, the present invention relates to a method of manufacturing a light guide plate used for a mobile phone, a PDA, a video camera, a car navigation system, a personal computer, a computer monitor, a television receiver, an advertising billboard, and the like, and a surface light source device including the same.

  Liquid crystal displays as small and large displays such as mobile phones, PDAs (Personal Digital Assistants), video cameras, and car navigation systems, personal computers, computer monitors, television receivers, advertising billboards, etc. The device is widely used. The liquid crystal display device is composed of a surface light source device (so-called backlight unit or front light unit) that emits light in a planar shape, and a reflective, transmissive, or transflective liquid crystal display panel that provides image information. Characters and images are displayed by controlling the reflectance or transmittance of light according to the image information provided by the display panel.

  As a method of a backlight unit which is an example of a surface light source device used in a liquid crystal display device, a primary light source composed of a fluorescent lamp or LED (light emitting diode, organic EL element, etc.), and light from the primary light source is used as side light. There are an edge light system that includes a light guide plate that enters from the incident surface, converts it into a planar light beam, and exits from the light exit surface, and a direct type method in which the primary light source is disposed directly below the liquid crystal display panel via a diffusion plate. . In a liquid crystal display device having a relatively small screen size, it is a mainstream to adopt an edge light system which is advantageous for thinning.

  Conventionally, in an edge light type backlight unit, an optical sheet such as a diffusion sheet or a light deflection sheet (prism lens sheet) is disposed on the light exit surface side of the light guide plate, and the light emitted from the light guide plate is transmitted to the liquid crystal display panel. It has been done to make the direction perpendicular to the direction. In recent years, attempts have been made to incorporate the functions of an optical sheet into a light guide plate by forming a micro structure such as a microprism on the light reflection surface or light output surface of the light guide plate for the purpose of reducing the thickness, weight, and cost. It is being considered.

  As the light guide plate incorporating the function of the optical sheet, for example, a member that becomes a light guide plate main body and a member having a microprism are provided, and the surface area of the light exit surface of the microprism is larger than the surface area of the light incident surface. A light guide plate having inclined side walls provided has been proposed (for example, see Patent Documents 1 to 4). However, since the light guide plate is composed of at least two members including a light guide plate main body and a member having a microprism, the light guide plate is not sufficiently thin, and the light guide plate main body and the microprism are optically completely coupled. This is difficult, and there is a problem in light utilization efficiency.

In response to the above problem, a single sheet light guide plate in which a light guide plate main body and a microprism are integrally formed has been proposed (see, for example, Non-Patent Document 1). A manufacturing method is disclosed in which a single sheet light guide plate is formed using a mold formed by a photoresist method and peeled off from the mold. However, the microprism may be partially lost when peeling from the mold. There has been a problem that the luminance of the surface light source device using the same becomes uneven.
JP-T-08-511129 Japanese National Patent Publication No. 10-511803 JP-A-10-255529 JP 2006-128072 A J. et al. Lee, H.C. Lee, B.H. Lee, W.H. Choi, H.H. Choi, J. et al. Yoon, "Optics Letters", 2007, 32, 18, 2665

  In view of the above problems, an object of the present invention is to provide a method of manufacturing a light guide plate with high yield by suppressing the loss of the convex portions when manufacturing a light guide plate having a plurality of convex portions.

  The present invention provides a light guide plate body having at least a light incident surface on which light emitted from a primary light source is incident, a light emitting surface from which guided light is emitted, and a light reflecting surface opposite to the light emitting surface, and the light A method of manufacturing a light guide plate having a plurality of convex portions on an output surface, wherein (1) a plurality of convex portions are formed on a light output surface by curing a curable resin using a mold having a concave portion corresponding to the convex portion. And a molding step for forming the light guide plate main body, and (2) a peeling step for peeling the formed convex portion and the light guide plate main body from the mold in this order, and the elastic modulus of the convex portion in the peeling step is the elastic modulus of the mold. It is a manufacturing method of the light-guide plate characterized by being larger than this.

  According to the present invention, it is possible to manufacture the light guide plate with a high yield by suppressing the missing of the convex portion. By using the light guide plate manufactured by the method of the present invention, a surface light source device with uniform luminance can be provided.

  The light guide plate according to the present invention includes a light guide plate body having at least a light incident surface on which light emitted from a primary light source is incident, a light exit surface from which the guided light is emitted, and a light reflecting surface opposite to the light exit surface. Have. Furthermore, it has a some convex part in the light-projection surface. By combining such a light guide plate with a primary light source, a surface light source device that guides light emitted from the primary light source and emits it in a planar shape can be obtained.

  The form of the light guide plate will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of the shape of the light guide plate in the present invention. A plurality of convex portions 1 are provided on the light emitting surface of the light guide plate body 2 having a light incident surface, a light emitting surface, and a light reflecting surface. The planar arrangement of the protrusions 1 may be regular or random, and the pitch is preferably in the range of 10 μm to 100 μm. The light incident on the light guide plate is totally reflected on the surface of the light exit surface other than the convex portion, and diffuses throughout the light guide plate while repeating total reflection with the opposite light reflecting surface.

  FIG. 2 is a schematic view showing an example of the convex shape of the light guide plate in the present invention. The convex portion 1 has an inverted truncated cone shape that widens in the height direction. Here, the light emitting surface side of the light guide plate body is the lower side and the opposite side is the upper side of the convex portion. The light that has entered the convex portion from the lower bottom 7 of the convex portion is reflected by the side surface 8 of the convex portion and is emitted from the upper bottom 6 of the convex portion. The convex portion has a shape that widens in the height direction, and is preferably an inverted polygonal truncated cone shape or an inverted truncated cone shape, and more preferably an inverted truncated cone shape. By forming the convex portion into a shape that widens in the height direction, light emitted from the upper base 6 of the convex portion can be efficiently guided in a direction perpendicular to the light guide plate. The efficiency of guiding the emitted light in the direction perpendicular to the light guide plate when the convex portion has an inverted truncated cone shape becomes higher. The diameter of the lower base 7 of the convex part is preferably 1 to 50 μm, and the height of the upper base 6 with respect to the lower base 7 of the convex part is preferably 0.5 to 30 μm. If the diameter and height of the bottom of the convex portion are within the above ranges, the light utilization efficiency is high, so the luminance is high when a surface light source is configured, and the luminance uniformity is high because the dimensional variation of the convex portion is small. it can.

  FIG. 3 is a schematic view showing an example of a liquid crystal display device equipped with the surface light source device of the present invention. Light from the primary light source 3 disposed on the side surface of the light guide plate body 2 passes through the inside of the light guide plate body 2, is reflected by the side surface of the convex portion 1, and is emitted to illuminate the liquid crystal display panel 4 of the liquid crystal display device. . In order to return the light emitted below the light guide plate main body 2 to the light guide plate, the reflection plate 5 can be arranged.

  Next, the manufacturing method of the light-guide plate of this invention is demonstrated. The manufacturing method of the light guide plate of the present invention includes (1) a molding step in which a curable resin is cured using a mold having a concave portion corresponding to the convex portion to form a plurality of convex portions and a light guide plate body on the light exit surface; (2) It has the peeling process which peels the formed convex part and the light-guide plate main body from a type | mold in this order. By this method, the light guide plate main body and the convex portion can be formed at the same time to obtain an integrally formed light guide plate. And this invention is characterized by the elastic modulus of a convex part being larger than the elastic modulus of a type | mold in the said peeling process. If the elastic modulus of the convex part is the same as or smaller than the elastic modulus of the mold, when the light guide plate having the convex part is peeled off from the mold, a defect in which the convex part of the light guide plate is easily lost occurs. It becomes difficult to produce industrially with good yield. In particular, when the shape of the convex portion is a shape that widens in the height direction, it is more important that the elastic modulus of the convex portion of the light guide plate is larger than the elastic modulus of the mold. In the present invention, the elastic modulus can be measured according to the tensile elastic modulus test method of JIS K7113 (1995). The elastic modulus of a convex part is obtained by producing a plate-like cured product under the same curing conditions and measuring the tensile elastic modulus. It is also possible to directly measure the elastic modulus of the convex portion of the light guide plate by the nanoindentation method. In the nano-indentation method, a slight force is applied to the indentation of a regular triangular pyramid consisting of a diamond tip and pushed into the surface of the sample, and the amount of indentation is measured in nano-order. Elastic modulus can be determined.

  Below, each process is demonstrated using drawing.

  First, FIG. 4 shows an example of a process for producing a matrix having a convex arrangement used in the method for manufacturing a light guide plate of the present invention. (B) By the chromium mask layer forming step, for example, the chromium mask layer 10 having an opening corresponding to the bottom of the convex portion is formed on one surface of the glass substrate 9 made of double-sided mirror-polished glass. Next, a negative photoresist layer 11 is formed on the chromium mask layer 10 by (c) a photoresist layer forming step. Next, in the exposure step (d), exposure is performed by irradiating ultraviolet rays through the diffusion plate 13 and the refractive index adjusting liquid 12 from the glass substrate surface opposite to the glass substrate surface on which the photoresist layer 11 is formed. Next, (e) the photoresist layer is developed by a development step to obtain a mold (convex matrix 14) having a convex array on the glass substrate.

  Next, FIG. 5 shows an example of a process for producing a rubber mold having concave portions corresponding to the convex array, as an example of producing a mold having concave portions corresponding to the convex portions used in the light guide plate manufacturing method of the present invention. . (A) The liquid rubber 15 is applied on the convex matrix 14 obtained by the above method by an application step. Next, in the (b) curing step, the liquid rubber is cured to obtain a liquid rubber cured product 16. Next, (c) the liquid rubber cured product 16 is peeled from the convex matrix 14 by a peeling step. If necessary, a mold release treatment step for releasing the mold surface that has been peeled off can be added.

  Next, an example of the manufacturing method of the light-guide plate of this invention is demonstrated using FIG. The manufacturing method of the light guide plate of the present invention includes (1) a molding step in which a curable resin is cured using a mold having a concave portion corresponding to the convex portion to form a plurality of convex portions and a light guide plate body on the light exit surface; (2) It has the peeling process which peels the formed convex part and the light-guide plate main body from a type | mold in this order.

  First, the process (1) will be described. (A) The curable liquid resin 17 is applied on the mold 18 having a concave portion corresponding to the convex portion, which is obtained by the above method, by the application step. Next, (b) the applied curable liquid resin is cured by a curing step. By this step, the plurality of convex portions and the light guide plate main body can be simultaneously formed on the light emitting surface, and the light guide plate can be integrally formed.

  Examples of a method for applying a liquid curable resin to a mold having a concave portion corresponding to the convex portion arrangement include an extrusion coating method, a spin coating method, a wire bar coating method, a curtain coating method, a roll coating method, a spray coating method, a dip method, and the like. An appropriate method such as a coating method in which a coating liquid is fluidly developed to form a sheet can be applied. In particular, the extrusion coating method can be preferably used as a highly accurate coating method in terms of film thickness uniformity and coating film surface smoothness. The extrusion coating method is a method in which a coating liquid is extruded from the slit head of a die head and applied while forming beads on an object to be continuously moved relative to the die head.

  Next, the process (2) will be described. (C) In the peeling step, the resin cured in (b) is peeled off to obtain the light guide plate 19. As a peeling method, for example, either one or both ends of a light guide plate or a mold having a concave portion corresponding to the convex portion arrangement are grasped and peeled along a curved surface obtained by cutting a part of a cylindrical shape. The method, or a light guide plate or a mold having a concave portion corresponding to the convex array, and the entire or part of the back surface of either one or both are adhered and held on a curved surface obtained by cutting a part of a cylindrical shape through an adhesive. There is a method of peeling along the curved surface. It is preferable that the angle (peeling angle) formed by the mold having the concave portion corresponding to the light guide plate and the convex portion arrangement is maintained at an acute angle.

  The material for forming the mold having the concave portion corresponding to the convex portion arrangement is liquid before curing, and is a liquid rubber that is cured by reaction with a curing component, heating, or irradiation with ultraviolet rays or an electron beam. Is preferred. Examples of the liquid rubber include liquid silicone rubber, liquid urethane rubber, and liquid fluororubber.

  As the liquid silicone rubber, room temperature curable silicone rubber is preferable. Either one liquid type or two liquid type (three liquid type) liquid structure may be used. Depending on the mechanism of the curing reaction, there are dealcohol-type, deoxime-type, deacetate-type, dehydroxylamine-type that cause condensation reaction with moisture in the air or catalyst, and addition-reaction type that causes hydrosilylation reaction with catalyst. Any type of room temperature curable silicone rubber may be used. In particular, the addition reaction type silicone rubber is more preferable in that it has no by-product accompanying the curing reaction, has a small curing shrinkage, and can easily be cured by heating. Examples of such materials include “Sylgard (registered trademark)” 184 manufactured by Dow Corning, and KE106 and KE1606 manufactured by Shin-Etsu Chemical Co., Ltd.

  Examples of the liquid urethane rubber include a thermosetting polyurethane having polyisocyanate and an active hydrogen-containing compound as constituent components. Examples of polyisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, isophorone diisocyanate, polymethylene poly (phenyl isocyanate), chemically modified polyisocyanates, and reactants such as these isocyanate compounds and polyols. Two or more of these polyisocyanates may be used. As the active hydrogen-containing compound, polyether polyol, polyester polyol, polyamine or the like can be used. When these compounds are blended to obtain a thermosetting polyurethane, a tertiary amine or an organic tin compound can be blended as a catalyst.

  The material for forming a mold having concave portions corresponding to the convex array (hereinafter sometimes referred to as a mold) preferably has a tensile modulus of 1 to 10 MPa, and more preferably 2 to 5 MPa. . By making the tensile elastic modulus within this range, the convex shape of the matrix can be accurately transferred, and moreover, when the light guide plate produced on the rubber mold is peeled off, the loss of the convex portion of the light guide plate is further suppressed. Can do. Further, when the light guide plate is peeled off, the opening of the concave portion of the mold undergoes tensile deformation because the upper bottom of the convex portion of the light guide plate is removed. For this reason, it is preferable that the material forming the mold has a sufficient elongation at break. The preferred elongation at break varies depending on the design of the convex shape, but is preferably 150% or more, and more preferably 200% or more. In the present invention, the elongation at break can be measured according to the tensile modulus test method of JIS K7113 (1995). Further, the material for forming the mold preferably has a small deformation energy represented by the area under the curve in the stress-strain diagram in the tensile test. Urethane rubber has a small tensile elastic modulus compared to silicone rubber, and it is easy to make a material with small deformation energy with a small amount of deformation accompanying an increase in deformation, and is preferable as a material for forming a mold. Can be used.

  The material for producing the light guide plate is preferably a liquid curable resin that is in a liquid state before curing, and is applied to a mold having a concave portion corresponding to the convex portion arrangement and spread and then becomes a sheet-like cured product by a curing reaction. . The liquid curable resin can be selected from a thermosetting resin, an ultraviolet curable resin, and an electron beam curable resin. Examples of the thermosetting resin include epoxy resins, modified epoxy resins, silicone resins, modified silicone resins, acrylate resins, urethane resins, and polyimide resins. Examples of the ultraviolet curable resin and the electron beam curable resin include epoxy acrylate, polyurethane acrylate, polyester acrylate, vinyl ether resin, epoxy resin, and oxetane resin.

  According to the manufacturing method of the present invention, a thin light guide plate with high light utilization efficiency can be manufactured with a high yield. The surface light source device using the light guide plate manufactured by the method of the present invention can be suitably used for a liquid crystal display device for mobile use.

  Hereinafter, the present invention will be described more specifically based on examples. In addition, this invention is not limited to the following Example. First, an evaluation method in each example will be described.

(1) Tensile modulus and elongation at break:
The liquid curable resin was mixed and degassed under reduced pressure, then developed on a flat plate made of “Teflon (registered trademark)”, kept horizontal, and heated in a hot air oven at 120 ° C. for 2 hours to obtain a thickness of 0. A plate-like cured product having a thickness of 5 to 1 mm was obtained. This plate-like cured product was cut out to have a width of 5 mm and a length of 50 mm, and was previously conditioned for 24 hours in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH. This sample was subjected to a tensile test under the conditions of an initial length of 20 mm and a tensile speed of 50 mm / min using a Tensilon universal testing machine RTM-100 (Orientec Co., Ltd.) in an atmosphere of 23 ° C. according to JIS K7113 (1995). It was. The tensile elastic modulus was calculated by the following equation using the first linear portion of the tensile stress-strain curve.
Em = Δσ / Δε
Em: Tensile modulus Δσ: Difference in stress due to the original average cross-sectional area between two points on a straight line Δε: Difference in strain between the same two points The elongation at break was calculated by the following equation.
l = {(L−L0) / L} × 100
l: elongation at break L: distance between marked lines at break L0: distance between original marked lines

(2) Convex part transferability:
The light guide plate formed 2 inches diagonal (width 30.5 mm, length 40.6 mm) was observed with a microscope, and the presence or absence of a convex portion was examined. The convexity transferability was determined to be good when there was no convexity missing on the entire 2 inch light guide plate.

(3) Average brightness and brightness uniformity:
The light guide plate with 2 inches diagonal (width 30.5mm, length 40.6mm) is arranged so that the surface on which the convex part is formed becomes the upper surface side, and four LEDs are arranged at equal intervals on the end surface side of one short side. And the reflecting plate was arrange | positioned to the opposing end surface, and the edge light type surface light source device was comprised. A luminance meter (“Topcon BM-7” manufactured by Topcon Corporation) was installed at a position 30 cm above, and the luminance (cd / m 2) was measured in a dark room. The average luminance was obtained by averaging a total of nine measured values of 3 levels in the width direction and 3 levels in the length direction. Further, the luminance uniformity was calculated by the formula (minimum luminance value / maximum luminance value) × 100 (%).

Production Example 1 (Production of convex mold matrix):
The matrix of the convex array was prepared by using 3D diffusion lithography described in Non-Patent Document 1 and Optics Express 2004, Vol. 12, pages 6366-6371. That is, a chromium mask layer having an opening corresponding to the bottom of the convex portion is formed on one surface of the glass substrate, and a negative photoresist (product number AZ2070 is formed on the surface of the glass substrate on which the chromium mask layer is formed. , Clariant) thin film was formed to a thickness of 12 μm. Ultraviolet rays were irradiated from the surface side opposite to the glass substrate surface on which the photoresist thin film was formed (ultraviolet light exposure amount 8640 mJ / cm ² ). At this time, a diffusion plate (product number NT02-149, Edmund Optics) and pure water as a refractive index adjusting liquid were arranged in this order from the side closer to the light source, and ultraviolet rays were irradiated through the diffusion plate and pure water. The exposed photoresist thin film was developed with a dedicated developer to prepare a matrix having a convex array. The obtained convex part had an average diameter of the upper base of 30.0 μm, an average diameter of the lower base of 12.9 μm, an average height of 12.0 μm, and an average inclination angle of the side surface of 54.5 degrees. The arrangement pitch of the convex portions was 40 μm on the light incident surface side and 60 μm on the opposite surface side, and was continuously changed.

Production Example 2 (Production of a silicone rubber mold having a concave portion corresponding to the convex portion arrangement)
A room temperature curable liquid silicone rubber (product number KE1606, Shin-Etsu Chemical Co., Ltd., main agent / curing agent mixed weight ratio = 100/10) was degassed by depressurizing at 1,000 Pa for 10 minutes, and then subjected to the method of Production Example 1. It was applied by spin coating to the surface of the glass substrate on which the fabricated convex array matrix was formed. The liquid silicone rubber was cured by maintaining the level and heating at 120 ° C. for 2 hours. The silicone rubber mold having a recess corresponding to the convex array was prepared by peeling the cured silicone rubber from the matrix of the convex array. The surface of the mold is subjected to oxygen plasma treatment (100 W, 60 Pa, 30 seconds) to give release properties to the liquid curable resin, and then tridecafluoro-1,1,2,2-tetrahydrooctyltri Chlorosilane (Fluka) vapor was exposed. The room temperature curable liquid silicone rubber cured product after heating at 120 ° C. for 2 hours had a tensile modulus of 2.3 MPa and a breaking elongation of 530%.

Production Example 3 (Production of urethane rubber mold having a concave portion corresponding to the convex portion arrangement)
100 g of polyisocyanate (product number “Coronate (registered trademark)” 4403, Nippon Polyurethane Industry Co., Ltd.) and 109 g of polyol (product number “Nipporan (registered trademark)” 4226, Nippon Polyurethane Industry Co., Ltd.) are mixed to obtain a liquid urethane rubber composition. After being prepared and degassed under reduced pressure at 1,000 Pa for 10 minutes, it was applied by spin coating to the surface of the glass substrate on which the matrix of convex portions prepared by the method of Production Example 1 was formed. The liquid urethane rubber composition was cured by maintaining the level and heating at 120 ° C. for 2 hours. A mold having a concave portion corresponding to the convex array was produced by peeling the urethane rubber after curing from the matrix of the convex array. The cured liquid urethane rubber composition cured product after heating at 120 ° C. for 2 hours had a tensile modulus of 4.6 MPa and a breaking elongation of 260%.

Production Example 4 (Production of silicone rubber mold having a concave portion corresponding to the convex portion arrangement)
A room temperature curable liquid silicone rubber (product number “Sylgard” 184, Dow Corning, main agent / curing agent mixed weight ratio = 100/10) was defoamed at 1,000 Pa for 10 minutes and then defoamed. It was applied by spin coating to the surface of a glass substrate on which a convex array matrix produced by the method was formed. The liquid silicone rubber was cured by maintaining the level and heating at 120 ° C. for 2 hours. The silicone rubber mold having a recess corresponding to the convex array was prepared by peeling the cured silicone rubber from the matrix of the convex array. The surface of the mold is subjected to oxygen plasma treatment (100 W, 60 Pa, 30 seconds) to give release properties to the liquid curable resin, and then tridecafluoro-1,1,2,2-tetrahydrooctyltri Chlorosilane (Fluka) vapor was exposed. The room temperature curable liquid silicone rubber cured product after heating at 120 ° C. for 2 hours had a tensile modulus of 2.8 MPa and a breaking elongation of 150%.

Example 1
A liquid curable silicone rubber composition (Part No. X-32-2557, Shin-Etsu Chemical Co., Ltd., main agent / curing agent mixed weight ratio = 100/100) was degassed by depressurizing at 1,000 Pa for 10 minutes, and then Production Example The liquid curable silicone rubber composition was applied to the surface of a silicone rubber mold having concave portions corresponding to the convex portion arrangement produced by the method 2 by the extrusion coating method. The liquid silicone rubber composition was cured by maintaining the level and heating at 120 ° C. for 2 hours. The cured silicone rubber was peeled from the urethane rubber mold to produce a light guide plate having an average thickness of 0.5 mm.

As a result of observing the convex portion formed on the surface of the light guide plate with a microscope and examining the presence or absence of the convex portion, the convex portion was not missing on the entire surface of the 2-inch pattern, and the convex portion transferability was good. The average luminance was 2,850 cd / m ² and the luminance uniformity was 75%.

  The cured liquid silicone rubber composition cured at 120 ° C. for 2 hours had a tensile modulus of 5.2 MPa and a breaking elongation of 104%.

Example 2
The liquid curable silicone rubber composition (“Sylgard” 184, Dow Corning, main agent / curing agent mixed weight ratio = 100/10) was degassed by depressurizing at 1,000 Pa for 10 minutes, and then the method of Production Example 2 The liquid curable silicone rubber composition was applied to the surface of a silicone rubber mold having concave portions corresponding to the convex portion arrangement produced by the above-described method by an extrusion coating method. The liquid silicone rubber composition was cured by maintaining the level and heating at 120 ° C. for 2 hours. The cured silicone rubber was peeled from the silicone rubber mold to produce a light guide plate having an average thickness of 0.5 mm.

As a result of observing the convex portion formed on the surface of the light guide plate with a microscope and examining the presence or absence of the convex portion, the convex portion was not missing on the entire surface of the 2-inch pattern, and the convex portion transferability was good. The average luminance was 2,830 cd / m ² and the luminance uniformity was 75%.

  The cured liquid silicone rubber composition cured at 120 ° C. for 2 hours had a tensile modulus of 2.8 MPa and a breaking elongation of 150%.

Example 3
Liquid epoxy resin (product number YL7217, Japan Epoxy Resin Co., Ltd. and product number EP4000, ADEKA Co., Ltd., mixing weight ratio = 100/100) 100 g and methylhexahydrophthalic anhydride (product number Ricacid MH-700, Shin Nippon Rika Co., Ltd.) ) 53 g, 1.5 g of curing accelerator (product number Hishicolin PX-4MP, Nippon Chemical Industry Co., Ltd., methyltributylphosphonium dimethyl phosphate) was mixed to prepare a liquid curable epoxy composition, and the pressure was reduced at 1,000 Pa for 10 minutes. After defoaming, a liquid curable epoxy composition was applied to the surface of a silicone rubber mold having recesses corresponding to the projection array produced by the method of Production Example 2 by an extrusion coating method. The liquid curable epoxy composition was cured by maintaining the level and heating at 120 ° C. for 2 hours. The cured epoxy resin was peeled from the silicone rubber mold to produce a light guide plate having an average thickness of 0.5 mm.

As a result of observing the convex portion formed on the surface of the light guide plate with a microscope and examining the presence or absence of the convex portion, the convex portion was not missing on the entire surface of the 2-inch pattern, and the convex portion transferability was good. The average luminance was 2,830 cd / m ² and the luminance uniformity was 75%.

  The cured epoxy composition after heating at 120 ° C. for 2 hours had a tensile modulus of 2.8 MPa and a breaking elongation of 147%.

Example 4
In the same manner as in Example 1, the liquid curable silicone rubber composition of Example 1 was applied to the surface of a urethane rubber mold having concave portions corresponding to the convex portion array produced by the method of Production Example 3 by the extrusion coating method. Then, a light guide plate having an average thickness of 0.5 mm was produced.

As a result of observing the convex portion formed on the surface of the light guide plate with a microscope and examining the presence or absence of the convex portion, the convex portion was not missing on the entire surface of the 2-inch pattern, and the convex portion transferability was good. The average luminance was 2,850 cd / m ² and the luminance uniformity was 75%.

Comparative Example 1
The liquid curable silicone rubber composition (“Sylgard” 184, Dow Corning, main agent / curing agent mixed weight ratio = 100/10) was degassed by depressurizing at 1,000 Pa for 10 minutes, and then the method of Production Example 4 The liquid curable silicone rubber composition was applied to the surface of a silicone rubber mold having concave portions corresponding to the convex portion arrangement produced by the above-described method by an extrusion coating method. The liquid silicone rubber composition was cured by maintaining the level and heating at 120 ° C. for 2 hours. The cured silicone rubber was peeled from the silicone rubber mold to produce a light guide plate having an average thickness of 0.5 mm.

As a result of observing the convex portion formed on the surface of the light guide plate with a microscope and examining the presence or absence of the convex portion, 6% of the convex portion was missing in the 2-inch pattern, and the convex shape transferability was poor. The average luminance was 2,800 cd / m ² and the luminance uniformity was 70%.

  The cured liquid silicone rubber composition cured at 120 ° C. for 2 hours had a tensile modulus of 2.8 MPa and a breaking elongation of 150%.

  The results of Examples 1 to 4 and Comparative Example 1 are summarized in Table 1.

It is the schematic which shows an example of the shape of the light-guide plate in this invention. It is the schematic which shows an example of the convex part shape of the light-guide plate in this invention. It is the schematic which shows an example of the liquid crystal display device carrying the surface light source device of this invention. It is a figure which shows an example of the manufacturing process of the matrix of the convex part arrangement | sequence used for the manufacturing method of the light-guide plate of this invention. It is a figure which shows an example of the production process of the rubber type | mold which has a recessed part corresponding to the convex part arrangement | sequence used for the manufacturing method of the light-guide plate of this invention. It is a figure which shows an example of the manufacturing method of the light-guide plate of this invention.

Explanation of symbols

1: convex part 2: light guide plate body 3: primary light source 4: liquid crystal display panel 5: reflector 6: upper base of convex part 7: lower base of convex part 8: side surface of convex part 9: glass substrate 10: chrome mask Layer 11: Photoresist layer 12: Refractive index adjusting liquid 13: Diffusion plate 14: Convex part mold 15: Liquid rubber 16: Liquid rubber cured product 17: Curable liquid resin 18: Mold having a concave part corresponding to the convex part 19: Light guide plate

Claims (4)

A light guide plate main body having at least a light incident surface on which light emitted from the primary light source is incident, a light emitting surface from which the guided light is emitted, and a light reflecting surface opposite to the light emitting surface, and a plurality of light guide surfaces on the light emitting surface (1) A plurality of convex portions and a light guide plate main body on a light emitting surface by curing a curable resin using a mold having a concave portion corresponding to the convex portion. And (2) a peeling step for peeling the formed convex portion and the light guide plate body from the mold in this order, and the elastic modulus of the convex portion is larger than the elastic modulus of the die in the peeling step. A method of manufacturing a light guide plate characterized by the above. The convex part has an inverted truncated cone shape that widens in the height direction, the diameter of the lower base is 1 to 50 μm, and the height of the upper base relative to the lower base is 0.5 to 30 μm. The method for manufacturing a light guide plate according to claim 1. The method for manufacturing a light guide plate according to claim 1, wherein the mold includes silicone rubber or urethane rubber. The surface light source device containing the light-guide plate obtained by the method in any one of Claims 1-3, and a primary light source.

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