JP5566581B2 - Surface light emitter and manufacturing method thereof - Google Patents

Description

  The present invention relates to a surface light emitter used for an edge light type backlight unit of a liquid crystal display device such as a mobile phone and a thin notebook personal computer, and a method for manufacturing the same.

  Conventionally, a surface emitting device has been used as a backlight unit of a transmissive liquid crystal panel. As the surface light-emitting device, various edge-light type surface light-emitting devices in which light from a light source is incident from the side of a flat light guide member and light is emitted from one main surface have been proposed (for example, Patent Document 1). To 4).

  FIG. 6 is a cross-sectional view showing an example of the configuration of a conventional surface light emitting device. The surface light emitting device 60 is disposed on the light source 61, the light guide plate 62, the diffusion sheet 64 and the prism sheet 65 disposed on the light exit surface 62a side of the light guide plate 62, and the lower surface 62b side opposite to the light exit surface 62a. A reflection sheet 66 is included, and these members are held by a frame (not shown). In addition, a light diffusion pattern 63 having a concavo-convex shape is provided on the lower surface 62b of the light guide plate 62 so as to emit light uniformly.

In the surface light emitting device 60, as shown in FIG. 6, light emitted from the light source 61 enters the light guide plate 62 from the light incident surface 62c and propagates through the light guide plate 62 while undergoing total reflection. . At that time, a part of the propagation light is diffused by the light diffusion pattern 63 provided on the lower surface 62b of the light guide plate 62, and the angle formed with the normal line of the emission surface 62a is smaller than the critical angle, whereby the emission surface 62a. It is emitted from. The light passing through the lower surface 62b of the light guide plate 62 is reflected by the reflection sheet 66, returns to the light guide plate 62 again, and then exits from the exit surface 62a.
JP 2007-108799 A JP 2007-535790 A JP 2007-535790 A JP 2007-535790 A

  In such a surface light emitting device, the light guide plate is also required to be thinly formed in order to reduce the thickness and weight of the liquid crystal display device and the like. As a main manufacturing method of the conventional light guide plate, there is an injection molding method.

  However, as long as the injection molding method is employed, the thickness of the light guide plate is limited due to the problem of filling properties of the resin that is a constituent material of the light guide member. For example, many light guide plates used for cellular phones and the like are molded in a thickness range of about 0.5 mm. Although it is possible to reduce the thickness somewhat by injection molding using a large injection molding machine with high injection pressure, there is still a limit in terms of resin filling properties. In addition, there is a problem that the equipment cost of a large injection molding machine increases. Further, in the injection molding method, if the size of the light guide plate is different, it is necessary to prepare an injection mold separately, and the mold cost is also increased.

  On the other hand, a manufacturing method by continuous roll transfer, that is, roll-to-roll transfer has been devised. In roll-to-roll transfer, a means for curing the resin coated on the base film mainly by ultraviolet or electron beam irradiation is used, and a roll-shaped mold having a concavo-convex pattern formed on the surface is used. The shape of the concavo-convex pattern is transferred to the resin. Such roll-to-roll transfer is an effective means for reducing the thickness of the light guide plate, and a film-like flexible light guide plate manufactured by roll-to-roll transfer has been devised.

  However, in roll-to-roll transfer, curling occurs because the resin is cured by ultraviolet rays or electron beams in the state where the film is in contact with the roll along the curved surface of the roll. There is a problem such as. Also, since the uneven pattern of the light guide plate is usually exposed, when the light guide plate is stored and transported in a roll shape, the back surface and the surface of the light guide plate are in contact with each other, and the uneven pattern is deformed by the winding pressure, There is a problem that the surface or the surface on which the uneven pattern is not formed (back surface) is damaged, and measures such as giving the light guide plate a certain level of strength and hardness, and attaching a protective film to the uneven surface It will be necessary.

  An object of the present invention is to realize a surface light emitting device that can be thinned, can suppress deformation of a light diffusion pattern, and can be easily manufactured at low cost by eliminating defects in a conventional manufacturing process. The object is to provide a light-emitting body and a method of manufacturing the same.

A first aspect of the present invention is a reflective film in which a light diffusion pattern having a concavo-convex shape is formed on one side and wound into a roll, and a reflective film fed out from a roll along the concavo-convex shape of the light diffusion pattern; And the light guide layer is selected from a photosensitive resin composition, a thermosetting resin composition, a radiation curable resin composition, and a thermoplastic resin composition. at least it consists of one light transmitting resin composition that, the light guide layer, have a tack or adhesion, a surface light emitter, characterized by being rolled up.

A second aspect of the present invention is a surface light-emitting device having a surface luminous body according to the first aspect, and a light source disposed on a side of the light guide layer.

A third aspect of the present invention is a liquid crystal display device including the second surface light emitting device as a backlight unit.

According to a fourth aspect of the present invention, there is provided a step of forming a light diffusion pattern having a concavo-convex shape on one side of a reflection film and winding it into a roll, and a reflection film fed from a roll along the concavo-convex shape of the light diffusion pattern Forming a light guide layer so as to adhere, wherein the light guide layer is selected from a photosensitive resin composition, a thermosetting resin composition, a radiation curable resin composition, and a thermoplastic resin composition at least consists one of a light transmitting resin composition, the light guide layer, tackiness or adhesion possess, the method for manufacturing a surface-emitting body, characterized in that it is made in a roll-to-roll is is there.

According to a fifth aspect of the present invention, in the method for manufacturing a surface light emitter according to the fourth aspect, the step of forming the light diffusion pattern is performed by any one of printing, hot stamping, and laser processing. And

According to a sixth aspect of the present invention, in the method for manufacturing a surface light emitter according to the fourth or fifth aspect, in the step of forming the light guide layer, a light-transmitting resin composition is applied on the reflective film. Including a process.

According to a seventh aspect of the present invention, in the method for manufacturing the surface light emitter according to the fourth or fifth aspect, the light guide layer forming step is performed by applying a light-transmitting resin composition on the release film. And a step of transferring the resin composition applied onto the release film onto the reflective film.

  According to the present invention, the light guide layer is formed so as to be in close contact with the reflection film along the uneven shape of the light diffusion pattern formed on the reflection film, and the both are integrated. The surface is not exposed, and the uneven pattern shape is not deformed by the winding pressure when stored and transported in a roll. Therefore, it is not necessary to design the hardness to maintain the uneven shape, and the degree of freedom in designing the hardness can be increased. Moreover, since it is not necessary to provide a protective film on the uneven surface, the manufacturing cost can be reduced and the production efficiency can be increased. Furthermore, since the surface light emitter of the present invention can be manufactured by an extremely easy method of forming a light diffusion pattern on the reflective film side and forming a light guide layer on the reflective film, the manufacturing process can be simplified and Cost reduction can be realized. In addition, since it is not necessary to use a roll-shaped mold when forming the light guide layer, problems in the conventional manufacturing process can be solved. Furthermore, since the light guide layer can be formed to a desired thickness on the reflective film on which the light diffusion pattern is formed, the restriction on the thickness of the light guide layer as in the case of using the injection molding method is relaxed. Thus, the surface light emitter and the surface light emitting device and liquid crystal display device including the surface light emitter can be reduced in thickness.

Embodiments of the present invention will be described below in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a surface light emitting device 10 according to a first embodiment of the present invention. The surface light emitting device 10 includes a light source 1 and a surface light emitter 11 including a light guide layer 12 and a reflective film 13. The light guide layer 12 has a light incident surface 12c on which light from the light source 1 is incident and an output surface 12a that emits incident light from the light incident surface 12c. A light diffusion pattern 14 having a concavo-convex shape is formed on one side of the reflection film 13 so that light incident on the light guide layer 12 is uniformly emitted from the emission surface 12 a of the light guide layer 12.

  As shown in FIG. 1, the light guide layer 12 is formed so as to be in close contact with the reflective film 13 along the uneven shape of the light diffusion pattern 14 formed on the reflective film 13. In this way, in the surface light emitter 11 having a structure in which the light guide layer 12 and the reflection film are in close contact with each other, the uneven surface of the light diffusion pattern 13 is not exposed, so the surface light emitter 11 is rolled. The concave / convex pattern shape is not deformed by the winding pressure when stored and transported in the form. Therefore, it is not necessary to design the hardness to maintain the uneven shape, and the degree of freedom in designing the hardness can be increased. Moreover, since it is not necessary to provide a protective film on the uneven surface, the manufacturing cost can be reduced and the production efficiency can be increased.

  The material constituting the light guide layer 12 is at least one light transmissive selected from a photosensitive resin composition, a thermosetting resin composition, a radiation curable resin composition such as ultraviolet rays, and a thermoplastic resin composition. A resin composition can be used.

  The light guide layer 12 can be cured by chemical crosslinking using a crosslinking agent or the like, or by irradiation with ionizing radiation such as heat or ultraviolet rays. When curing with a crosslinking agent, a polyisocyanate compound, a melamine compound, an epoxy compound, or the like can be used as the crosslinking agent. In the case of curing with ionizing radiation such as heat or ultraviolet rays, the polymer resin is a monomer or oligomer containing a (meth) acryloyl group such as urethane acrylate or epoxy acrylate, or a side chain such as an acrylic polymer resin ( ) A polymer containing a polymer having an acryloyl group introduced therein can be used. When the light guide layer is cured by ultraviolet irradiation, a photopolymerization initiator such as isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, Benzyl dimethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethylphenylpropane and the like can be used.

  Moreover, the light guide layer 12 may have adhesiveness or adhesiveness. As a resin composition having adhesiveness or adhesiveness, by changing the blending amount of the crosslinking agent or photopolymerization initiator in the polymer resin, or by partially changing the type and number of substituents, What expressed adhesiveness or adhesiveness can be used. Thus, the light guide layer 12 has adhesiveness or adhesiveness, so that, for example, other optical components such as a diffusion sheet and a prism sheet, a light source, and the like can be used without providing the adhesive layer or the adhesive layer. 12 can contribute to the thinning of the surface light emitting device and the simplification of the manufacturing process.

  As a material constituting the reflection film 13, a general reflection film can be used. For example, a white PET film in which a polyethylene terephthalate (PET) film is filled with a filler such as titanium oxide and air bubbles, or a PET film is silver. A reflective film in which a silver reflective film is formed by vapor deposition or silver sputtering, and a PET film laminated with a metal foil such as aluminum can be used.

  The shape of the light diffusion pattern 14 of the reflective film 13 is not particularly limited, and may be any shape as long as it has an uneven shape having a light diffusion effect, such as a dot shape or a prism shape. The arrangement pattern of the unevenness is not limited to be constant, and for example, a pattern in which the uneven pitch is gradually changed or a pattern in which the unevenness is partially provided may be used.

Below, the manufacturing method of the surface light-emitting body of the said structure is demonstrated.
First, an uneven light diffusion pattern 14 is formed on one surface of the reflective film 13. A method for forming the light diffusion pattern 14 is not particularly limited, and examples thereof include various printing, hot stamping (foil pressing), and laser processing. In order to efficiently obtain a desired uneven pattern, a method by rotary hot stamping is preferable.

  Next, the light guide layer 12 is formed on the reflection film 13 on which the light diffusion pattern 14 is formed so as to be in close contact with the reflection film 13 along the uneven shape of the light diffusion pattern 14. Examples of the method for forming the light guide layer 12 include a method of applying a light transmissive resin composition constituting the light guide layer on the light diffusion pattern forming surface of the reflective film 13. The coating method is not particularly limited, but roll coater coating, spin coater coating, spray coating, whey coating, dip coating coating, curtain flow coating coating, wire bar coating coating, gravure coating coating, air knife coating coating, die coating coating, etc. Can be mentioned.

  Since the resin composition applied on the reflective film 13 is also filled in the concave portions of the light diffusion pattern 14, a coating film in close contact with the reflective film 13 is formed along the uneven shape of the light diffusion pattern 14. Then, the surface emitting body 10 with which the light guide layer 12 and the reflective film 13 were integrated can be obtained by performing a drying process and a hardening process as needed to a coating film. In the case where the light guide layer 12 is made of a resin having adhesiveness or adhesiveness, the optical film is cured by applying a coating film after attaching another optical component to the light guide layer 12. Can be adhered and fixed.

  In addition, you may implement each said manufacturing process continuously within 1 line by what is called a roll-to-roll system. When adopting the roll-to-roll method, first, a roll-shaped reflective film 13 on which the light diffusion pattern 14 is formed is sent out from the roll, and the light guide layer 12 is applied on the reflective film 13 and then dried and necessary. In response to this, a curing process such as UV irradiation is performed, and finally the reflection film 13 on which the light guide layer 12 is formed is wound into a roll. Prior to winding, a release film may be laminated, slitted, punched, or the like as necessary. According to such a roll-to-roll system, the light guide layer can be continuously formed while the reflective film remains in a roll shape (endless shape), and thus it is possible to reduce the manufacturing process costs and save labor. Become.

In addition, when the surface has irregularities like the reflective film of the present invention, and a solvent-based resin is used for the light guide layer and the solvent is volatilized by drying, the above-described coating method is used. Then, it may be difficult to form a uniform light guide layer with a constant thickness. In such a case, as a method for forming the light guide layer 12, a so-called transfer method may be employed instead of the coating method as described above. In the transfer method, a light-transmitting resin composition constituting the light guide layer is applied onto a smooth release film, and the coating film temporarily attached onto the release film and the reflective film 13 are bonded together and applied. The light guide layer 12 is formed on the reflective film 13 by transferring the film onto the reflective film 13.
Even in such a transfer system, a roll-to-roll system capable of continuous transfer and integration can be employed.

  According to the manufacturing method of the surface light emitter as described above, the surface light emitter 10 is formed by an extremely easy method such as forming the light diffusion pattern 14 on the reflective film 13 side and forming the light guide layer 12 on the reflective film 13. Since it can be manufactured, the manufacturing process can be simplified and the cost can be reduced. In addition, since a roll-shaped mold is not used when forming the light guide layer 12, curling of the light guide layer 12 can be suppressed, there is no problem of releasability, and problems in conventional manufacturing processes are eliminated. can do. Moreover, since the light guide layer 12 can be formed to a desired thickness on the reflective film 13 on which the light diffusion pattern 14 is formed, the thickness of the light guide layer is limited as in the case of using an injection molding method. Is reduced, and the surface light emitter 11 and the surface light emitter device 10 including the surface light emitter 11 can be reduced in thickness.

(Second Embodiment)
FIG. 2A is a cross-sectional view showing a surface light emitting device 20A according to the second embodiment. The surface light-emitting device 20A of this embodiment is different from the structure of the surface light-emitting device 10 shown in FIG. 1 only in that the optical function sheet 21A is bonded to the emission surface 12a of the light guide layer 12. Examples of the optical function sheet 21A include a diffusion sheet effective for reducing luminance unevenness and a prism sheet having a characteristic of improving light emission luminance, and may be an optical sheet group combining these. According to such a surface light emitting device 20A, by providing the optical function sheet 21A, it is possible to reduce luminance unevenness and improve light emission luminance.

  Instead of the flat optical functional sheet 21A as shown in FIG. 2A, an optical functional sheet 21B having holes or irregularities as shown in FIG. 2B may be used. Part of the optical function sheet 21 </ b> B comes into contact with the light guide layer 12 and is bonded to the light guide layer 12. Examples of the optical function sheet 21B include a diffusion sheet and a prism sheet, as in the optical function sheet 21A, and may be an optical sheet group in which these are combined.

  In the surface light emitting devices 20A and 20B, as described above, when the light guide layer 12 has adhesiveness or adhesiveness, the optical function sheets 21A and 21B are not provided with an adhesive layer or an adhesive layer. It can be bonded to the light guide layer 12 and is effective in reducing the thickness of the surface light emitting device and simplifying the manufacturing process.

(Third embodiment)
FIG. 3 is a cross-sectional view showing a surface light emitting device 30 according to the third embodiment. The surface light emitting device 30 of the present embodiment is different from the configuration of the surface light emitting device 10 shown in FIG. 1 only in that it includes a light introduction block 32 for increasing the incidence efficiency on the light guide layer 12. The light introduction block 32 has a shape such that the thickness gradually decreases as the distance from the light incident surface 33 facing the light source 2 increases. The refractive index of the light introduction block 32 is desirably the same as the refractive index of the light guide layer 12.
According to such a surface light emitting device 30, even when the light source 2 thicker than the light guide layer 12 is used as shown in the drawing, the light from the light source 2 can be efficiently incident.

  In the surface light emitting device 30, the light introduction block 32 may be bonded to the light guide layer 12, thereby suppressing light loss at the interface 34 between the light introduction block 32 and the light guide layer 12. At this time, as described above, when the light guide layer 12 has adhesiveness or adhesiveness, the light introduction block 32 can be bonded to the light guide layer 12 without providing the adhesive layer or the adhesive layer. Therefore, the manufacturing process can be simplified.

(Fourth embodiment)
FIG. 4 is a cross-sectional view showing a surface light emitting device 40 according to the fourth embodiment. The surface light emitting device 40 of this embodiment is different from the structure of the surface light emitting device 10 shown in FIG. 1 only in that the light source 1 is bonded to the light incident surface 12 a of the light guide layer 12. According to the surface light emitting device 40, it is possible to suppress light loss at the light incident surface 12 a that is an interface between the light source 1 and the light guide layer 12. Also in the surface light emitting device 40, when the light guide layer 12 has adhesiveness or adhesiveness, the light source 1 can be bonded to the light guide layer 12 without providing an adhesive layer or an adhesive layer. Therefore, the manufacturing process can be simplified.

(Fifth embodiment)
Next, a liquid crystal display device provided with the surface light emitting device of the present invention as a backlight unit will be described.
FIG. 5 is a cross-sectional view showing the configuration of the liquid crystal display device 50. The liquid crystal display device 50 includes the surface light emitting device 20A illustrated in FIG. 2A and a transmissive liquid crystal display panel 51.

  In the liquid crystal display device 50, the light emitted from the light source 1 enters the light guide layer 12 from the light incident surface 12c, and propagates through the light guide layer 12 while repeating total reflection. At that time, propagating light is diffused by the light diffusion pattern 14 provided on the upper surface of the reflection film 13, and the angle formed with the normal line of the emission surface 12 a becomes smaller than the critical angle, and is emitted from the emission surface 12 a. The light emitted from the light guide plate 12 is polarized and diffused by passing through the optical function sheet 21 </ b> A, and illuminates the liquid crystal display panel 51.

  In the liquid crystal display device 50, by using the surface light emitting device 20A of the present invention as a backlight unit, thickness reduction and cost reduction are realized. Instead of the surface light emitting device 20A shown in FIG. 2A, the surface light emitting devices 10, 20B, 30 and 40 shown in FIGS. 1, 2B, 3 and 4 may be used.

It is sectional drawing which shows the surface light-emitting device concerning one Embodiment of this invention. (A) is sectional drawing which shows the surface emitting device concerning 2nd Embodiment, (b) is sectional drawing which shows the modification of the surface emitting device concerning 2nd Embodiment. It is sectional drawing which shows the surface light-emitting device concerning the 3rd Embodiment of this invention. It is sectional drawing which shows the surface emitting device concerning the 4th Embodiment of this invention. It is sectional drawing which shows the liquid crystal display device provided with the surface emitting device of this invention. It is sectional drawing which shows an example of the conventional surface emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Light source 10,20A, 20B, 30,40 Surface light-emitting device 11 Surface light emitter 12 Light guide layer 12a Output surface 12c Light incident surface 13 Reflective film 14 Light diffusion pattern 21A, 21B Optical function sheet 32 Light introduction block 50 Liquid crystal Display device 51 LCD panel

Claims (7)

A reflective film in which a light diffusion pattern having an uneven shape is formed on one side and wound into a roll;
A light guide layer formed so as to be in close contact with the reflective film sent out from the roll along the uneven shape of the light diffusion pattern;
The light guide layer is composed of at least one light transmissive resin composition selected from a photosensitive resin composition, a thermosetting resin composition, a radiation curable resin composition, and a thermoplastic resin composition,
The light transmissive resin composition has adhesiveness or adhesiveness, and the light guide layer is formed by curing the light transmissive resin composition after the light transmissive resin composition is disposed on the reflective film fed from a roll.
A surface light emitter which is wound into a roll. A surface light emitter according to claim 1;
A surface light emitting device having a light source installed on a side surface of the light guide layer.   A liquid crystal display device comprising the surface light emitting device according to claim 2 as a backlight unit. Forming a light diffusion pattern having a concavo-convex shape on one side of the reflective film and winding it into a roll; and
Forming a light guide layer so as to be in close contact with the reflective film fed from the roll along the uneven shape of the light diffusion pattern,
The light guide layer is composed of at least one light transmissive resin composition selected from a photosensitive resin composition, a thermosetting resin composition, a radiation curable resin composition, and a thermoplastic resin composition,
The light transmissive resin composition has adhesiveness or adhesiveness, and the light guide layer is formed by curing the light transmissive resin composition after the light transmissive resin composition is disposed on the reflective film fed from a roll.
A method of manufacturing a surface light emitter, wherein the method is manufactured roll-to-roll.   The method for manufacturing a surface light emitter according to claim 4, wherein the step of forming the light diffusion pattern is performed by any one of printing, hot stamping, and laser processing.   The method for producing a surface light emitter according to claim 4, wherein the step of forming the light guide layer includes a step of applying a light transmissive resin composition on the reflective film. The light guide layer forming step includes:
Applying a light transmissive resin composition on the release film;
The method for producing a surface light emitter according to claim 4, further comprising a step of transferring the resin composition applied onto the release film onto the reflective film.

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