JPH07178833A - Manufacture of back light - Google Patents

Abstract

PURPOSE:To reduce the number of defective products by integrating respective parts or layers simultaneously as far as possible when a back light of a surface light source is manufactured by a method wherein a light diffusion finely irregular part, a light reflecting layer, and a light diffusing layer are inserted into an injection die, and they are molded integrally with a light introducing board. CONSTITUTION:A metal part 8 having an irregular part for shaping is fixed to a movable mold 3 of an injection die. A light source 5, and a connector part for a light source 6 are provided on a fixing mold 2 of the die, and a peeling layer, a reflecting layer, a diffusing layer, an adhesive layer, etc., are laminated in this order on a base film. The adhesive layer side of this transfer sheet 7 is opposed to a cavity side of the injection die, and melt resin is injection molded to form a light introducing board consisting of a transparent resin wherein a light diffusion finely irregular part on a light emission side is integrated. Simultaneously therewith, the light source 5, the connector part for the light source 6, the reflecting layer, the diffusion layer, etc., are integrated. After injection molding, the base film is peeled off to manufacture an integrated light source of an edge light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a backlight used for liquid crystal display screens, lighting advertisements, etc., and particularly to a light source section, a light guide plate made of a transparent resin, a light diffusing fine concavo-convex section, a light diffusing layer, A light source is located on the side of the light guide plate, and a light-diffusing fine uneven portion is formed on the light-exiting surface side of the light-guide plate, and a light-reflecting layer is formed on the back surface side via a light-diffusing layer, or a light-diffusing layer. A method for manufacturing a surface light source backlight in which layers are provided.

[0002]

2. Description of the Related Art Conventionally, as a surface light source backlight used for a liquid crystal display screen or the like, an edge light type surface light source in which a light source section is arranged on a side portion of a light guide plate as shown in FIG. As shown in FIG. 3 (2), there is a light guide plate provided with a light source section on the back surface. As a method for manufacturing this surface light source backlight, Japanese Patent Laid-Open Nos. 1-24590 and 2-17,
No. 4,107,201 and the like are known, in which light-diffusing fine irregularities on the light emitting surface side made of a film provided with irregularities (lenses), a light guide plate made of a transparent resin portion, polyester, metal Reflector with coating or kneading diffuser on the surface of plate, fluorescent tube, incandescent bulb, E
Light sources using L, LEDs, etc. are manufactured separately and laminated in a post process to manufacture a surface light source backlight.
In JP-A-2-84618, a light source 80 is provided on the side surface of the light guide plate 81 as shown in FIG.
An edge light type in which a satin-finished fine unevenness 82 is formed on one surface, a prism sheet 83 is formed on the one surface, and the satin-finished surface and the prism face each other, and a reflective layer 84 is laminated on the other surface of the light guide plate 81. An area light source is disclosed. Also in this case, the prism sheet is prepared separately from the light guide plate and integrated by a heat press or the like to manufacture an edge light type surface light source. In any of the above methods, a step of integrating individual or some parts or layers is required, and in order to manufacture a surface light source backlight, the number of steps is large, it is troublesome, and the number of defects is also a step. It accumulated and increased every time, which was a problem.

[0003]

Under the circumstances, the present invention integrates each part or layer at the same time as much as possible when manufacturing a surface light source backlight, and saves time and effort.
The present invention is intended to reduce the number of defects, and to provide a manufacturing method that can be mass-produced and can be qualitatively adapted.

[0004]

The present invention comprises a light source section, a light guide plate made of a transparent resin, a light diffusing fine concavo-convex section, a light diffusing layer, and a reflecting layer. A light diffusing fine concavo-convex portion on the light emitting surface side of the light guide plate,
A method for manufacturing a surface light source backlight for use in a liquid crystal display screen or the like, in which a light reflecting layer or a light diffusing layer is provided on the back side through a light diffusing layer. When a light guide plate made of is injection-molded, at least a light-diffusing fine concavo-convex portion, a light-reflecting layer, and a light-diffusing layer are inserted in the injection-molding die, and the light-guide plate is integrally molded by injection molding. Is included. Further, according to the present invention, when a light guide plate made of a transparent resin is injection-molded by using an injection molding die, a light source section, a light-diffusing fine concavo-convex portion, a light-reflecting layer, and a light-diffusing layer are formed in the injection-molding die. It is integrally formed with the light guide plate by inserting and inserting it. Then, on either surface of the movable mold or the fixed mold of the injection molding die, an injection molding uneven portion having the same shape as the light diffusion fine uneven portion for forming the light diffusion fine uneven portion is formed by injection molding. Arranged so that it faces the cavity side of the mold, injection-mold the light guide plate made of transparent resin, remove the mold, peel off the imprinting irregularities from the molded light guide plate, and guide the light diffusion fine irregularities. As shown in FIG. 1, a metal part 8 having an imprinting uneven portion is fixed to a movable mold 3 of an injection mold, and a light source 5 and a light source are fixed to a fixed mold 2 of the mold. Connector part 6, release layer on the base film,
A transfer sheet 7 in which a reflection layer, a diffusion layer, an adhesive layer, etc. are laminated in this order is made so that the adhesive layer side faces the cavity side of the injection molding die, and the molten resin is injection-molded, and the light-diffusing fine irregularities on the light-emitting side The light source 5, the light source connector portion 6, the reflection layer, the diffusion layer, and the like are integrated at the same time when the light guide plate made of a transparent resin in which the parts are integrated is formed, and the base film is peeled off after injection formation and integrated. Create an edge light source.
Here, instead of the metal portion 8 having the unevenness portion for molding for producing the light-diffusing fine unevenness portion, the unevenness side of the molding sheet having the unevenness portion on the surface of the resin sheet faces the cavity side of the injection molding die. In this way, the light guide plate made of transparent resin may be injection-molded, and after injection molding, the entire shaping sheet may be peeled off from the light guide plate side to integrally form the backlight.
Then, in FIG. 1, instead of the transfer sheet 7, a light guide plate made of a transparent resin is injection-molded so that the light-diffusing layer-provided reflection plate faces the cavity side of the injection-molding die. May be integrally molded with the plate, and instead of the transfer sheet 7, a plate in which a reflective layer and a diffusing agent for producing a light diffusing layer are kneaded is a plate in which the diffusing agent is kneaded. Alternatively, the light guide plate made of a transparent resin may be injection-molded so as to face the cavity side and integrally molded. Here, the transfer foil, the transfer film, the transfer sheet and the like are collectively referred to as a transfer sheet.

As the imprinting irregularities for producing the light-diffusing surface-side diffused fine irregularities, those having the same shape as the light-diffusive fine irregularities on the metal surface, and the reverse irregularities produced by etching or cutting, or light on the film are used. There is one using a shaping film or a shaping sheet provided with an uneven portion having the same shape as the diffused fine unevenness or the reverse unevenness, and the light diffusive fine uneven portion is formed at the same time when the light guide plate is injection-molded using these as a mold. Here, the shape-imparting film or the shape-imparting sheet is generically referred to as a shape-imparting sheet, and the films or sheets used are also collectively referred to as a sheet. In the method using a patterning sheet, as shown in FIG. 6, a hard film that can be further peeled from the concave-convex portion on the concave-convex portion 53 of the patterning sheet 51 in which the concave-convex portion 53 is formed on the base material sheet 52 with resin. By forming 54, it is possible to transfer the hard film to the light guide plate side at the same time when the light emitting surface side diffusion fine unevenness is formed at the time of injection molding of the light guide plate. In this case, since the shape of the light emitting surface side diffusion fine unevenness is covered with a hard film,
It will be loyal to the durable design and shape-free design. In order to improve the adhesiveness and transferability between the hard layer and the layer to be molded, an adhesive layer 55 is provided on the hard layer 54 as shown in FIG. Can also be transferred to the light guide plate side. The concavo-convex shape is the reverse concavo-convex shape that is the same as the lens shape to be formed, and as the lens shape, a triangular prism linear array (Fig. 4 (1)), a convex or concave lenticular lens (Fig. 4 (2)), a random grain , Matte shape such as satin (Fig. 4 (3)), pyramid lens array (Fig. 4)
(4)), a hemispherical lens array (fly-eye lens), a Fresnel lens, and the like.

The case where the shape of the light-diffusing surface side diffused fine irregularities of the surface light source backlight is produced using a shaping sheet will be described below. Here, as the base material sheet for the shape-imparting sheet to be used, it is easy to remove from the mold, easily peels off from the resin plate to be molded, and has strength as a shape-imparting sheet,
Materials that can be applied to the molding process are selected, but linear polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polymethylpentene, linear polyamides such as nylon 6 and nylon 66, polyvinyl chloride. Made of thermoplastic resin such as polyarylate, polyimide, or metal plate such as iron, copper, aluminum, lead, or foil, and has a thickness of about 12 to 200 μm and is flexible. It When the shaped sheet is preformed and formed, a base material sheet made of a thermoplastic resin is used. Further, in order to form the uneven shape of the shape-imparting sheet, it may be directly formed on the base material sheet by hot pressing, casting (casting) or the like, but preferably 3 on the base material sheet. A three-dimensional crosslinked resin layer is provided, and an uneven shape is formed on the surface by a casting method. As an example of the casting method using this three-dimensional crosslinked resin, Japanese Patent Laid-Open No.
No. 223883, U.S. Pat. No. 4,576,850, and the like. In this case, an easy-adhesion primer is previously formed on the base material sheet, if necessary. As a primer when forming the uneven shape of the shaping sheet,
A two-component curing type coating composition that uses an acrylic polyol as a main component and an isocyanate-based curing agent is mentioned, but it is not limited to this as long as the adhesive force between the three-dimensional cross-linking resin which is the uneven portion and the base sheet is sufficient. Examples of the three-dimensional cross-linking resin that forms the uneven portion include a thermosetting resin made of epoxy, unsaturated polyester, acryl, urethane, or the like, or an ionizing radiation curable resin.

[0007] A method for producing a pattern-forming sheet having a concave-convex portion having the same shape as the light-diffusing fine irregularities on the sheet, and a method for producing a transfer sheet having a peelable hard film on the concave-convex portion of the patterning sheet. Will be briefly described. First, a method for manufacturing a shaped sheet will be described with reference to FIG. First, a film base material 40 such as a biaxially stretched PET (polyethylene terephthalate) having a thickness of 75 μ (HP-7, Teijin), which has been subjected to an easy-adhesion treatment on one side.
Is passed between the primer coating roll 42 and the impression cylinder roll 43, and the primer 41 such as isocyanate-cured urethane is transferred from the ink pan to the coating roll. The transferred primer is further applied from the application roll to one surface of the film substrate on which the uneven shape is formed and transferred. However, if there is sufficient adhesion between the film substrate and the ionizing radiation curable resin without a primer, this primer application can be omitted. Next, the film base material coated with the primer is dried in a drying zone 44, and then the film base material 40 and the ionizing radiation curing resin liquid 45 are rotated around a shaft which is supplied and filled in the concave portion by a nozzle coating device. The roll intaglio 46 to be, between the nip rolls 47a, 47b consisting of at least two pieces, is brought into close contact with the surface of the film base material on which the primer is applied, and this is irradiated with ionizing radiation by an ionizing radiation irradiation device 48, The ionizing radiation curable resin cures and is integrated with the film substrate. At the same time, the shape of the roll intaglio is molded into a cured resin. After passing through the final nip roll 47b, the film base material and the molded cured resin are peeled off from the roll intaglio plate to obtain a shaped film sheet 49 having an uneven shape. A transfer sheet that transfers a hard film at the same time as forming the uneven portion when forming the light-diffusing fine unevenness of the surface light source backlight is formed by forming the uneven portion on the uneven surface of the shaping film sheet 49. Heat or ionizing radiation curable resin that can be peeled from the sheet is applied by gravure coating, roll coating, etc.,
It is produced by cross-linking and curing to form a hard film on the uneven portion.

The reflective layer on the back surface of the light guide plate is usually formed by a transfer method or a laminating method. In the case of the transfer method, when a light guide plate made of a transparent resin is injection-molded from a transfer sheet in which a release layer, a reflection layer, a diffusion layer, and an adhesive layer are laminated in this order on the base film by gravure printing, silk printing, etc. ,
It is transferred together with the light diffusion layer. Here, PET (polyethylene terephthalate) having a thickness of 38 μm as the base film, PMMA (polymethylmethacrylate) having a thickness of 2 μm as the peeling layer, and C as the reflecting layer (hiding layer) were used.
A metal thin film formed by vapor deposition of r, Al, etc., a light diffusion layer having a thickness of 2 μm in which titanium oxide, alumina, silica, resin, beads, etc. are mixed in acrylic, and an adhesive layer is acrylic, styrene. One having a thickness of 2 μ can be mentioned. In the case of the laminating method, only the reflection layer, the diffusion layer, and the adhesive layer are provided on the base film, and the peeling layer is not laminated. When the light guide plate is injection-molded, the base film is left as it is and is not peeled. Even in the case of the type directly below the light source as shown in FIG. 3B, it is preferable to provide a reflective layer in order to efficiently use the emission energy. For example, the light source part on which the reflective layer has already been formed on the back surface is inserted as it is into the injection molding die to be integrated. Of course, the reflection layer, the light diffusion layer and the EL light emitting layer produced by the conventional method may be separately put in a mold and integrated together with the injection molding of the light guide plate.

As the injection molding method, general injection molding may be used, but in consideration of the distortion of the molded product, the compression molding method is particularly preferable. When the sheet and the transfer foil are put in a mold and injection-molded, the sheet and the transfer foil are placed along the mold surface by clamping, vacuuming or the like. As the material of the mold, metal or ceramic is used. And, the gate is preferably a side gate as shown in FIG. By doing so, the high-speed melting resin injected from the gate can be made to collide with the resin flow relaxation wall 99 once to reduce the flow velocity and pressure, and then flow toward the cavity 97 on the left side. Therefore, it is possible to prevent the shaping sheet and the transfer sheet from being deformed or broken by the high-speed molten resin. In addition, it is possible to prevent the generation of bubbles and gas by allowing the molten resin to gradually flow from one end (the right end in FIG. 8) of the cavity to the other end to fill the cavity.

In order to insert the light source into the mold, the connector part is exposed outside the molded product, or the mold is prepared so that the wiring is exposed outside the parting surface. Then, a light source section is provided on the back surface (the surface opposite to the light emitting surface) or the side surface of the light guide plate. The light source is previously inserted into a mold and is laminated or transferred at the same time as the injection molding of the light guide plate. When the light source section is provided on the side surface of the light guide plate, it can be separated from the transfer sheet for forming the light reflection layer or the like, but as shown in FIG. 7, the light reflection layer is formed on the same base material sheet 61. Light source 6 with 63 mag
A method in which 6 is set as a part of the transfer layer and this is transferred is desirable and excellent in productivity. In the case of the transfer sheet 60 shown in FIG. 7A, after being set in the mold, FIG.
As shown in FIG. 7, the entire transfer sheet 60 with the light source 66 as a part of the transfer layer begins to bend, and the resin is injected along with this, so that the entire transfer sheet 60 has a shape conforming to the mold. The surface light source type backlight can be manufactured by simultaneously molding the light guide plate in a desired shape by injection molding. As the light source, a material that can be formed into a thin film and can withstand heat and pressure during injection molding is used. In the injection molding method using a hot-melt resin and the compression molding method using a heat-softening resin,
Electroluminescent (EL) devices are good. In reactive injection molding (RIM molding) that generates less heat during molding, in addition to EL elements,
Light emitting diodes (LEDs) can also be used. In the present invention,
It is necessary to obtain a highly transparent molded article with high optical uniformity. In the case of molten resin injection molding, as a preferred embodiment therefor, a shaping sheet is used for forming the light-diffusing fine irregularities, and a shaping sheet and a sheet for shaping the light-diffusing layer and the light-reflecting layer are used together. The base material is a material having a lower thermal conductivity than the mold. By doing this, the resin injected into the cavity is evenly filled throughout the cavity,
Since the material is cooled and solidified in a state where the internal stress is sufficiently relaxed, it is possible to obtain a weld line and a light guide plate with less optical distortion. When the metal mold is used, it is preferable to use a synthetic resin having a thickness of 50 μm or more as a base material sheet of a shaping sheet, a transfer sheet or a laminate sheet.

[0011]

In the method for manufacturing a surface light source backlight according to the present invention, the light source portion, and at least one of the light diffusing fine concavo-convex portion, the light diffusing layer, and the reflecting layer are inserted into the injection molding die and made of a transparent resin. By injection-molding the light guide plate and integrally molding it, the number of steps for manufacturing the surface light source backlight can be reduced. Further, when the light guide plate is injection-molded, the inside of the injection mold is It is possible to integrate all of the above by inserting the light source section, the light-diffusing fine unevenness section, the light-reflecting layer, and the light-diffusing layer in advance and performing injection molding. As a result, in the manufacturing method of the present invention, compared to the conventional method in which each part or layer is separately manufactured and then integrated, the labor is saved and the accumulation of defects in each step for integration is reduced. It Further, by using a transfer sheet provided with a hard layer having easy peeling property on the uneven portion of the shape-imparting sheet for producing the light-diffusing fine uneven portion, the light-diffusing fine uneven portion has good durability, Also, it is faithful to the design value that does not have any shape distortion. After all, from the above,
The surface light source backlight manufacturing method of the present invention can be provided in terms of quality and mass production.

[0012]

Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining the process of the first embodiment. Hereinafter, description will be given with reference to FIG. First, as shown in FIG. 1, a light source 5, a light source connector 6, a base film made of polyester, a release layer, a reflection layer, a diffusion layer, and an adhesive layer were laminated in this order on a fixed mold 2 of an injection molding die. The transfer sheet 7 was fixed so that the adhesive layer side faced the cavity side of the injection molding die. The transfer sheet 7 was vacuumed and fixed by a vacuuming line 9, and the light source section 5 was fixed by a light source connector section 6 fixed in a fixing groove. Next, a metal part 8 for forming having the same shape as the light-diffusing fine unevenness to be formed on the movable mold 3 of the injection-molding die is fixed so that the concave-convex portion side faces the cavity direction of the mold. did. Next, after moving the movable mold 3 of the injection molding die and clamping it with the fixed mold, the molten P was heated to 250 ° C. for producing the light guide plate.
Gate 4 of MMA (polymethylmethacrylate)
To form a light guide plate made of a transparent resin that integrates the light-diffusing fine concavo-convex portion on the light exit side, and at the same time, forms the light source 5, the light source connector section 6, the reflection layer, and the diffusion layer using an EL surface emitter. Integrate, remove the mold, peel off the base film,
An edge light source was made.

A second embodiment of the present invention will be given. A second embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic diagram for explaining the process of the second embodiment. Hereinafter, description will be given with reference to FIG. First, as shown in FIG. 2, a metal part 18 for forming having a forming unevenness having the same shape as the light-diffusing fine unevenness and the reverse unevenness,
It was fixed to the fixed die 12 of the injection molding die 11 so that the concavo-convex portion side faced the cavity direction of the mold, and concavo-convex was formed on the cavity side during molding. Then, the reflective layer transfer foil 1 is placed in the mold.
7 is put in, clamped by a clamp part 20, and evacuated by a vacuum evacuation line 19, and after moving the transfer foil 17 to the movable mold 13 of the mold, the clamp part is removed, and the fluorescent tube with a connector is connected to the connector part 16 And the fluorescent tube portion 15 were inserted in the position in the mold so that they would match when the mold was clamped. Then, after moving and clamping the movable mold, PMMA (polymethylmethacrylate) heated to 250 ° C. and melted is injected to form the light guide plate having the light diffusing fine concavo-convex portion at the same time as the reflection layer, The light source is integrated. After cooling for 20 seconds, the mold was opened, the film 17a of the reflective layer transfer foil 17 was peeled off, and an edge light type backlight integrated by injection molding was obtained.

A third embodiment of the present invention will be described. In the same manner as in Example 2, a metal imprinting unevenness for producing a light diffusing fine unevenness portion was fixed to a fixed mold of an injection molding die, and the unevenness was formed on the cavity side at the time of molding, and then the injection was performed. For molding dies,
16 μm thick PET (polyethylene terephthalate)
A film obtained by coating an aluminum vapor-deposited reflective layer having a thickness of 4 μm on a film was clamped and fixed to a movable part of a mold in the same manner as the reflective layer transfer foil of Example 2, and was evacuated to be along the movable part. Next, the EL element surface-generating body was fixed and inserted into a position in the mold corresponding to the end portion of the light guide side surface. Next, after moving the movable die and clamping it, 250 ° c
PMMA (polymethylmethacrylate) which was heated and melted was injected to form a light guide plate having a light diffusing fine concavo-convex portion, and at the same time, the reflection layer and the light source portion were integrated. 20 sec
After cooling, the mold was opened, and an edge light type backlight integrated by injection molding was obtained.

[0015]

EFFECTS OF THE INVENTION According to the present invention, with the above-mentioned structure, the number of steps for manufacturing a surface light source backlight is different from the conventional method of separately manufacturing each part and layer and then integrating them. The number of defects can be reduced and the number of defects that occur can be reduced. And, further, at the time of injection molding of the light guide plate, the light source section, the light diffusion fine uneven section,
It is possible to integrate all of the light diffusion layer and the reflection layer. Further, the present invention, by using the shaping sheet,
It is not necessary to provide an expensive metal mold having an uneven pattern, and by using a transfer sheet in which an easily peelable hard film is provided on the uneven part of a shaping sheet, the light diffusing fine uneven part is formed as a hard film of the transfer sheet. Can be transferred to produce a light guide plate provided with an uneven shape made of a hard film. As a result, the surface durability and wear resistance are better than in the case where the lens shape is provided only by the molding resin, and the uneven shape does not collapse as compared with the case where a hard film is coated on the uneven shape part. It enables the production of products that are faithful to the shape. After all, the present invention can provide a manufacturing method of an edge light type backlight that can be used in terms of quality and can be mass-produced.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a first embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a second embodiment of the present invention.

[Figure 3] Surface light source backlight diagram

FIG. 4 is a diagram of an imprinted uneven portion for producing light-diffusing fine unevenness in the present invention.

FIG. 5 is a schematic view of the manufacturing process of the shaped sheet of the present invention.

FIG. 6 is a diagram for explaining a shaping sheet and a light guide plate corresponding to the shaping sheet according to the present invention.

FIG. 7 is a diagram showing an example of integrally molding a light source unit according to the present invention.

FIG. 8 is a diagram showing an example of a cavity and a gate of an injection mold according to the present invention.

FIG. 9 is a diagram of a conventional edge light type surface light source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11 Injection mold 2, 12 Fixed mold 3, 13 Movable mold 4, 14 Gate gate 5, 15 Light source 6, 16 Light source connector part 7, 17 Transfer sheet 17a Sheet part 17b Reflective layer 8, 18 For imprinting Metal parts 9, 19 Vacuuming line 20 Clamping part 40 Base material sheet 41 Primer 42 Coating roll 43 Impressor 44 Drying zone 45 Resin liquid 46 Roll intaglio 47a, 47b Nip roll 48 Ionizing radiation irradiation device 49 Imprinting sheet 50 Uneven shape part 51 Molding sheet 52 Base material sheet 53 Concavo-convex shaped portion 54 Hard film 54a Hard film after transfer 55 Adhesive layer 55a Adhesive layer after transfer 56 Transparent resin molding plate 57 Light guide plate 60 Transfer sheet 61 Base material sheet 62 Release layer 63 Reflective layer 64 Light diffuse reflection pattern 65 Adhesive layer 66 EL layer Light source 67 Female type 6 Male type 69 Gate gate 70 Cavity 71 Vacuum line 72 Ejection resin 80 Light source 81 Light guide plate 82 Satin finish fine irregularities 83 Prism sheet 84 Reflective layer 91 Mold 92 Fixed type 93 Movable type 94 Gate gate 95 Film 96 Metal parts for imprinting 97 Cavity 98 Slide core 99 Resin flow relaxation wall

Claims (5)

[Claims] 1. A light source section and a light guide plate made of transparent resin,
A light diffusing fine concavo-convex part, a light diffusing layer, and a reflecting layer. A light source part is arranged on the side or back surface of the light guide plate. The light diffusing fine concavo-convex part is on the light emitting surface side of the light guide plate and the light diffusing layer is on the back surface side. A method of manufacturing a surface light source backlight for use in a liquid crystal display screen or the like, in which a light reflecting layer or a light diffusing layer is provided via a light guide plate made of a transparent resin using an injection molding die. At the time of molding, at least the light-diffusing fine concavo-convex portion, the light-reflecting layer, and the light-diffusing layer are inserted in the injection molding die, and a step of integrally molding with the light guide plate by injection molding is included. And a method for manufacturing a backlight. 2. The light source section, the light diffusing fine concavo-convex portion, the light reflecting layer, and the light in the injection molding die according to claim 1, when a light guide plate made of a transparent resin is injection molded using the injection molding die. A method for manufacturing a backlight, wherein all the diffusion layers are inserted and injection-molded to be integrally molded with the light guide plate. 3. The reverse concavo-convex shape having the same shape as that of the light-diffusing fine concavo-convex portion for producing the light-diffusing fine concavo-convex portion, on one surface of either the movable die or the fixed die of the injection molding die. The molding irregularities are arranged so as to face the cavity side of the injection molding die, the light guide plate made of transparent resin is injection molded, and the mold irregularities are removed from the molded light guide plate. A method for manufacturing a backlight, which comprises peeling and molding the light-diffusing fine concavo-convex portion integrally with the light guide plate. 4. The method for manufacturing a backlight according to claim 3, wherein the unevenness portion for shaping is an unevenness portion of a shaping sheet in which the unevenness portion is provided on the surface of the resin sheet. 5. The shape-imparting sheet according to claim 4, wherein a hard film made of a three-dimensional cross-linking curable resin that can be peeled from the shape-imparting sheet is provided on the surface of the uneven portion of the shape-imparting sheet, and the shape-imparting sheet is released. A method for manufacturing a backlight, characterized in that only the light-diffusing fine irregularities made of a hard film are formed integrally with the light guide plate on the light emitting surface side of the light guide plate.