JPH09267424A - Sheet member for surface light source device - Google Patents

Abstract

(57) An object of the present invention is to provide a sheet member for a surface light source device, which facilitates fixing work of the sheet member at the time of manufacturing the surface light source device and can improve the fixing accuracy. A sheet member (10) for transmitting and reflecting light, etc. in a surface light source device, wherein a portion (A) on an end portion side excluding an effective surface portion for transmitting and reflecting light on the sheet surface,
A band-shaped adhesive layer 12 is formed along the edge, and the adhesive layer 1
A release paper 13 having an area larger than that of the belt is releasably adhered onto the sheet 2 to cover the adhesive layer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet member for a surface light source device used in various surface light source devices such as a backlight of a liquid crystal display, an illumination display, and an illuminating body.

[0002]

2. Description of the Related Art Conventionally, a thin display device using a liquid crystal such as a personal computer, a word processor, a liquid crystal television, etc. does not emit light from the liquid crystal itself, so that a backlight for illuminating the liquid crystal display screen from the back side is used. There is. As such a backlight, an edge light type surface light source device in which a light source is installed on an end face portion of a light guide plate is adopted because the display device itself can be made thin and compact.

This edge light type surface light source device is
As shown in FIG. 3, the light guide plate 21, the light source 20 arranged on one end surface of the light guide plate 21, and the light guide plate 21 arranged on the back surface side of the light guide plate 21 to emit light from the back surface of the light guide plate 21. A reflection sheet 22 for reflecting the light that is generated and a diffusion sheet 24 that diffuses the light emitted from the light emission surface of the light guide plate 21.
And a light-condensing sheet 23 that collects the light transmitted through the diffusion sheet 24 in the central portion of the surface light source to enhance the front brightness. As described above, by using the diffusion sheet 24 and the light condensing sheet 23, the optical path of the light emitted from the light emitting surface of the light guide plate 21 is controlled. Further, in order to enhance the light diffusion effect and the like between the sheet members of the reflection sheet 22, the diffusion sheet 24, and the light condensing sheet 23 by utilizing the difference in the refractive index from the air.
An air layer 25 is provided. In FIG. 3, 27 is a reflection cover that reflects the light from the light source.

In the above-mentioned surface light source device, the light guide plate 21, the sheet members of the reflection sheet 22, the diffusion sheet 24, and the light collecting sheet 23 are positioned during assembly, and the sheet members are displaced from each other during handling or the like. Therefore, there is a problem that the assembly accuracy is deteriorated. Therefore, in order to prevent the sheet members from being displaced from each other and improve the productivity, it is desirable to fix the sheet members in a stacked state.

In this way, the air layer 25 is formed between the sheet members.
In order to fix the sheet members to each other while maintaining the above, each sheet member is manufactured to be slightly larger than the effective surface portion through which light is transmitted, etc., and the end-side portion (FIG.
The sheet members are fixed to each other by using A) in the above.

Various methods such as a heat-sealing method, an adhesive method, and an adhesive method can be cited as a method of fixing the above-mentioned end side portion A of each sheet member. Among these, the method of using a double-sided pressure-sensitive adhesive sheet in which a release paper is laminated on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet can fix each sheet member before the assembly processing, and the work time is short, and the position shift is caused. It can be easily reworked and is performed as an excellent method compared to other methods. Then, as shown in FIG. 3, the sheet members are fixed to each other via the adhesive layer 26 of the double-sided adhesive sheet.

The fixing of each sheet member with the double-sided adhesive sheet as described above is performed as follows. That is,
First, the double-sided pressure-sensitive adhesive sheet is cut into strips of a predetermined width, the release paper on one side is peeled off to expose the pressure-sensitive adhesive surface, and the pressure-sensitive adhesive surface exposed on this one surface is attached to the portion A on the end side of the sheet member. . Then, the release paper on the other surface of the double-sided adhesive sheet attached to the sheet member is peeled off to expose the adhesive surface,
It is performed that the sheet member is affixed to the portion A on the end side of another sheet member, and the sheet members to which the double-sided pressure-sensitive adhesive sheet is affixed are fixed together.

[0008]

However, in the above method, since the double-sided pressure-sensitive adhesive sheet cut into a predetermined width is used, the width and area of the pressure-sensitive adhesive and the release paper are the same, and the pressure-sensitive adhesive is peeled from that state. Only the paper must be stripped and removed. For this reason, when removing the release paper, it is necessary to hook the corners and the like of the release paper with the tip of the toe and peel it off a little, and to pinch the minutely peeled portion with the tip of the toe and gradually peel it off. As described above, it is difficult and troublesome to create a trigger for peeling, and there is a problem that the workability of fixing the sheet members to each other is extremely poor, which causes a cost increase.

On the other hand, in recent surface light source devices, it has been desired to reduce the area of a portion that is not effective for light transmission as much as possible in accordance with the miniaturization and weight reduction of various devices using the surface light source device. . Therefore, when fixing the sheet members using the double-sided pressure-sensitive adhesive sheet as described above, the area of the portion A on the end side is formed as small and narrow as possible, and the cutting width of the double-sided pressure-sensitive adhesive sheet is also as narrow as possible. However, it is desirable to reduce the width of the adhesive layer 26. However, it is difficult to cut the double-sided pressure-sensitive adhesive sheet with a narrow width, and moreover, it is difficult to accurately cut the double-sided pressure-sensitive adhesive sheet, and there is a problem in that winding misalignment and sheet breakage frequently occur. In addition, it is extremely difficult to accurately attach such a narrow double-sided pressure-sensitive adhesive sheet to the end portion A of the sheet member. Therefore, there is a limit in narrowing the width of the double-sided pressure-sensitive adhesive sheet, and there is a limit in downsizing the surface light source device itself.

The present invention has been made in view of the above circumstances, and makes it easy to fix the sheet member at the time of manufacturing the surface light source device, and further, it is possible to improve the fixing accuracy. The purpose is to provide.

[0011]

In order to achieve the above object, a sheet member for a surface light source device of the present invention is a sheet member for transmitting and reflecting light in the surface light source device, wherein A strip-shaped adhesive layer is formed along the edge on the edge side excluding the effective surface area such as transmission and reflection, and release paper with a larger area than the above strip can be peeled off on this adhesive layer. The gist is that it is adhered to and covered the adhesive layer.

That is, according to the present invention, a strip-shaped adhesive layer is formed along the edge at a portion on the end side of the sheet surface, and a release paper having an area larger than that of the strip can be peeled on the adhesive layer. Attached to. Therefore, on the release paper that covers the adhesive layer,
There are some areas that do not adhere to the adhesive. When the release paper is removed, the release paper can be removed very easily by pinching with the fingers and peeling off the non-adhering portion. Therefore, the workability of fixing the sheet members to each other when assembling the surface light source device is remarkably improved, and the assembling cost can be reduced.

Further, in the present invention, when the adhesive layer is formed by screen printing, it is possible to form the adhesive layer with a narrow band width and to form it with high accuracy. Therefore, it is possible to form the area A of the end portion side as small and narrow as possible, and to reduce the area of a portion of the sheet surface that is not effective for the transmission of light and the like, and to reduce the size of the surface light source device itself. Can be realized.

[0014]

Next, embodiments of the present invention will be described in detail.

FIG. 1 shows a sheet member for a surface light source device according to the present invention. That is, the strip-shaped adhesive layer 12 is provided on the end portion A of the sheet member 10 excluding the effective surface portion 11 through which light is transmitted. Then, the pressure-sensitive adhesive layer 12 is covered with a release paper 13 having an area larger than that of the strip. The release paper 13 has a portion 13a that is not adhered to the pressure-sensitive adhesive while being adhered to the pressure-sensitive adhesive layer 12.

As the sheet member 10, a reflecting sheet, a diffusing sheet, or a light collecting sheet is used.

As the reflecting sheet, various sheets can be used as long as they efficiently reflect the light transmitted through the light guide plate. Examples thereof include porous polyester film and porous polyolefin film. The reflective sheet preferably has a reflectance of 90% or more.

As the diffusion sheet, a transparent resin sheet made of polyethylene terephthalate, polycarbonate, polystyrene, acrylic resin, methacrylic resin or the like is used, and various porous sheets obtained by making these transparent resin sheets porous, or on the surface of the transparent resin sheet. Various types of materials that scatter and diffuse the transmitted light, such as a sheet that has been subjected to uneven treatment by sandblasting, solvent treatment, etc., a sheet on the surface of which a diffusion layer in which fine particles such as resin beads have been diffused is formed on a transparent resin base. What is used. The diffusion sheet preferably has a light transmittance of 80% or more and a haze value of 80% or more.

The light collecting sheet is made of transparent resin,
On the sheet surface, a large number of prism-shaped or wave-shaped ridges are formed side by side, or a large number of hemispherical or pyramid-shaped protrusions are formed, and if it has a function of collecting transmitted light in the central portion, Various types are used and are not particularly limited.

As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer, (meth) acrylic acid alkyl ester such as n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate and the like are used. , (Meth) acrylic acid, acrylic adhesive mainly composed of a copolymer such as itaconic acid, natural rubber, styrene-butadiene-random copolymer system, styrene-isoprene-styrene block system,
Various rubber-based adhesives such as styrene-butadiene-styrene block-based, styrene-ethylene-butylene-styrene block-based, butyl rubber-based, polyisobutylene-based, various silicone-based adhesives, vinyl acetate-based various vinyl-based adhesives, etc. Examples thereof include, but are not limited to, various types. Among these, the acrylic pressure-sensitive adhesive is particularly excellent from the viewpoint of heat resistance. In addition, these adhesives may be colored by containing a pigment or the like that absorbs light in order to reduce unevenness in brightness caused by reflection of light at the ends. Furthermore, these adhesives may contain rosin-based, chroman-indene-based, terpene-based, petroleum-based, styrene-based, phenol-based, and
Xylene-based tackifiers, polybutene, polyisobutylene, polyisoprene, process oils, naphthene-based oils and other softeners, phenol-based, amine-based antioxidants, ultraviolet absorbers, titanium white, zinc white, carbon carbide , Various fillers such as clay, talc, carbon, thiuram type,
Various kinds of crosslinking agents such as phenol type and isocyanate type may be blended.

Various methods such as a screen printing method, a constant discharge gun application method, a brush painting method, and a transfer method can be used to apply the adhesive to each sheet member. Of these methods, the screen printing method is the most suitable. It is preferably carried out. According to the screen printing method, there is an advantage that the band-shaped width of the pressure-sensitive adhesive layer can be narrowed and formed with high precision, and that the thickness can be easily controlled. In this case, the adhesive application pattern may be applied in various patterns such as a linear shape, a dotted line shape, and a dot shape, and is not particularly limited.

As the release paper, silicone resin on the surface,
Various films such as a plastic film laminated with a fluororesin or the like and a paper similarly coated with a surface or laminated are used and are not particularly limited. The thickness of the release paper is not particularly limited, but from the viewpoint of easy handling, it is 10 to 100.
It is preferably about μm.

The area of the release paper to the adhesive coated surface is
It is preferably about 1.1 to 20 times, more preferably about 2 to 15 times. That is, when it is less than 1.1 times, the area of the portion which is not in close contact with the pressure-sensitive adhesive that triggers the peeling when peeling the release paper is too small, and improvement in workability cannot be expected. On the other hand, if it exceeds 20 times, the area of the release paper that is not in close contact with the pressure-sensitive adhesive is too large, and the release paper may peel off or shift unexpectedly during handling, making it difficult to handle. There is.

The sheet member for a surface light source device of the present invention can be manufactured, for example, as follows. That is, first, sheet members such as a reflection sheet, a diffusion sheet, and a light collecting sheet are prepared. Then, a band-shaped adhesive layer is formed along the edge by screen printing on the end portion A of the sheet member excluding the effective surface portion where light is transmitted and reflected on the sheet surface. Next, a release paper having an area larger than that of the strip-shaped pressure-sensitive adhesive layer is stuck on the pressure-sensitive adhesive layer to cover the pressure-sensitive adhesive layer.

The surface light source device can be assembled in the following manner by using the sheet member for the surface light source device having the above structure. That is, first, of the release paper 13 of the sheet member,
Pick the part 13a that is not in close contact with the adhesive layer 12 with your fingers,
The adhesive layer 12 is pulled upward by using this portion as a trigger.
The adhesive surface of the adhesive layer 12 is exposed by peeling it off from the surface. Then, each sheet member (reflective sheet, diffusing sheet, light-condensing sheet) whose adhesive surface is exposed in this way and a light guide plate are prepared, and the reflective sheet is provided on the back surface side of the light guide plate and the adhesive surface is adhered. By stacking and fixing by force, the diffusion sheet and the light collecting sheet are stacked and fixed by the adhesive force of the adhesive surface on the surface side of the light guide plate. As a result, the light guide plate and each sheet member (reflection sheet, diffusion sheet, light collecting sheet) are stacked and fixed, and an air layer is formed between each member. A light source is attached to this to assemble a surface light source device (see FIG. 3).

[0026]

As described above, according to the sheet member for a surface light source device of the present invention, the release paper covering the adhesive layer has a portion which does not adhere to the adhesive. And when removing the release paper,
Pick the part that is not in close contact with your fingers as a trigger,
By peeling off, the release paper can be removed extremely easily. Therefore, the workability of fixing the sheet members to each other when assembling the surface light source device is remarkably improved, and the assembling cost can be reduced.

Further, in the present invention, when the pressure-sensitive adhesive layer is formed by screen printing, it is possible to form the pressure-sensitive adhesive layer with a narrow band width and with high precision. Therefore, it is possible to form the area of the end portion side as small and narrow as possible, and to reduce the area of the portion of the sheet surface that is not effective for the transmission of light, etc., and realize miniaturization of the surface light source device itself. You will be able to.

Next, examples will be described together with comparative examples.

[0029]

EXAMPLE An example in which the sheet member for a surface light source device of the present invention is applied to a reflection sheet will be shown.

The reflection sheet has a reflectance of 96% and a thickness of 1
A porous sheet having a porosity of 30% and made of a polyethylene resin of 50 μm was used. Set the above reflection sheet to the specified size (1
70 mm x 230 mm), set it in a screen printing machine, print an acrylic pressure-sensitive adhesive as an adhesive on the edge of the above reflection sheet with a width of 1.5 mm, and put it in a dryer to dry. Then, the solvent was removed and an adhesive layer was formed. As the release paper, a polyester film having a thickness of 25 μm and processed with silicone resin is used, and the width is 5
The pieces cut into mm were laminated and attached so as to cover the entire adhesive layer. Then, the film to which the release paper was attached was punched using a Thomson punching die to obtain a reflection sheet.

[0031]

[Comparative Example 1] Acrylic pressure-sensitive adhesive was applied on both sides of a polyester film having a thickness of 25 μm, and the thickness was 50 μm on one side.
The double-sided tape obtained by stacking release paper treated with silicone resin on the above paper was cut into 2.5 mm width using a slitter type cutting machine, and the porous tape used in the examples was used. It was attached to the edge of the sheet. Then
The same punching process as in the example was performed to obtain a reflection sheet.

Next, the assembly workability and the accuracy of the adhesive layer of each reflective sheet of the above-mentioned Example and Comparative Example 1 were measured.

As for the assembling workability, a light guide plate made of an acrylic resin having a thickness of 2.5 mm is used, and the release paper of each reflection sheet is peeled off and fixed on the light guide plate so that one person can fix it. The number that the worker was able to perform fixed processing per unit time was evaluated based on Comparative Example 1.

The accuracy of the adhesive layer is determined by the maximum apparent width (W2 in FIG. 2) of the 150 mm-long adhesive layer including waviness.
And the actual width (W1 in FIG. 2) when the undulation is not taken into consideration were measured, and the difference (W2-W1) was evaluated.

Table 1 below shows the evaluation results of the assembling workability and the accuracy of the adhesive layer.

[0036]

[Table 1]

From Table 1 above, it can be seen that in the embodiment, the number of units assembled per unit time is large and the workability is improved. During the assembling work, it was extremely easy to remove the release paper in the example, but it was difficult to remove it in the comparative example 1. Further, it can be seen that in the example, the accuracy of the adhesive layer is also improved as compared with the comparative example 1.

[0038]

Comparative Example 2 An attempt was made to obtain a reflection sheet in the same manner as in Comparative Example 1 except that the double-sided tape had a cut width of 1.5 mm.
However, the cutting width is too narrow, and when the double-sided tape is cut, winding deviation or sheet breakage occurs, and it is not possible to obtain a double-sided tape accurately cut and processed with a width of 1.5 mm. It was not possible to obtain a reflection sheet having a narrow width. On the other hand, as described above, in the embodiment, the reflection sheet having the width of 1.5 mm and the narrow adhesive layer is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a sheet member for a surface light source device of the present invention.

FIG. 2 is an explanatory view showing a sheet member for a surface light source device of the present invention.

FIG. 3 is a cross-sectional view showing a surface light source device.

[Explanation of symbols]

 10 Sheet Member 11 Effective Surface Part 12 Adhesive Layer 13 Release Paper A End Part

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G02F 1/1335 530 G02F 1/1335 530 G09F 9/00 336 G09F 9/00 336J

Claims (4)

[Claims] 1. A sheet member for transmitting and reflecting light in a surface light source device, wherein light is transmitted through the sheet surface,
A strip-shaped adhesive layer is formed along the edge on the end side part excluding the effective surface part such as reflection, and a release paper having a larger area than the above strip-shaped is peelably attached on this adhesive layer. A sheet member for a surface light source device, wherein the sheet member is attached to cover the adhesive layer. 2. The sheet member for a surface light source device according to claim 1, wherein the adhesive layer is formed by screen printing. 3. The area of the release paper for the band-shaped adhesive layer is
The sheet member for a surface light source device according to claim 1 or 2, which is 1.1 to 20 times. 4. The sheet member for a surface light source device according to claim 1, wherein the sheet member is any one of a reflection sheet, a diffusion sheet and a light condensing sheet.