JPH06347792A - Edge light illumination plate partially provided with light transmission communicating section between light transmission plate and plane reflection member - Google Patents

Abstract

PURPOSE:To provide a reflection pattern-forming technique for a novel edge light illumination plate by partially and selectively utilizing plane reflection members as reflection patterns to obtain patterns of uniform and stable reflectivity without executing screen printing of high-pigment content ink having many technical restrictions and to enable the assembling of the edge light illumination plate without a complicated assembling stage at the time of forming the reflection patterns of the edge light illumination plate. CONSTITUTION:Light transmission communicating sections 4 consisting essentially of a resin having the refractive index approximately equal to the refractive index of a light transmission plate 1 are partially installed between the light transmission plate 1 and the plane reflection members 3 and air layers existing between the light transmission 1 and the plane reflection members 3 are partially eliminated to introduce the propagating light in the light transmission plate 1 into a scattering reflector and to generate scattering reflection. The reflection parts corresponding to the light transmission communicating section 4 are eventually created.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a novel reflection pattern of an edge light illuminating plate used for a backlight of a liquid crystal display device or an illuminated signboard.

[0002]

2. Description of the Related Art 1) A reflective layer of an edge light illuminating plate has a pattern of an ink containing a white pigment or glass beads on a back surface of a light guide plate made of a transparent resin plate such as a polymethylmethacrylate cast plate or a polycarbonate plate. There have been proposed a printing method, 2) a sand matting method on the back surface of the light guide plate, 3) a method of engraving or casting a minute prism on the back surface of the light guide plate.
The sand mat method of 2) can create a reflective surface with a higher reflection efficiency in the normal direction of the light guide plate (hereinafter referred to as effective reflection efficiency) than the printing method, but it can be used to make the light intensity distribution on the illuminated surface uniform. It is difficult to pattern an indispensable reflection part, it costs a lot of money to wash and separate the blast material from the light guide plate after sandblasting, and the strength of the rough surface is weak, and the rough surface part is damaged during the assembly work of the planar illumination plate. The method of creating a micro prism of 3) is easy to attach and is not used in practice. Although it is possible to freely design the light intensity distribution and obtain an illumination plate with high effective reflection efficiency compared with the printing method, it is possible to perform engraving work and It takes a lot of cost to make a casting mold, and only some examples can be recognized for small illuminating plates.Many illuminating plates have a drawback that the reflective layer has a low effective reflection efficiency even though they are manufactured. 1) screen which is cheap It has been created in the printing method.

In the screen printing method, a resin binder, a white pigment or glass beads and a reflective layer ink composed of a solvent are directly printed on a light guide plate and dried. Total reflection occurs at a minute interface having a difference in refractive index between the binder in the dry ink layer and the white pigment or beads, and functions as a reflection layer of the edge light illuminating plate.

The effective reflection efficiency is proportional to the amount of the interface between the resin binder and the white pigment or glass beads, or the minute air particles mixed in the reflection layer. The ratio of the adhesive to the pigment should be a composition with a large amount of pigment, but the physical properties of the ink change as the pigment becomes higher, and the printability deteriorates, and the resolution at pattern printing decreases and the ink fluidity deteriorates. , Shortening the life of printing equipment due to increase in ink polishing power, interruption of continuous work due to ink drying during printing, reduction of ink adhesion to the light guide plate, insufficient strength of dry ink film, and other problems. Ink-containing inks have produced printing process reflective layers with insufficient effective reflection efficiency. Therefore, a large amount of light leaks to the lower side of the reflection surface, and in order to effectively collect this light, the scattering reflection film is separately mounted on the lower surface of the printing layer via the air layer by a complicated method.

The present invention obtains a reflection pattern having a high effective reflectance by selectively utilizing a planar reflection member as a reflection pattern without screen-printing a highly pigmented ink having many restrictions as described above. The present invention also provides a novel edge light illuminating plate reflection mechanism by which an edge light type planar illuminating plate unit can be assembled without a complicated assembly process.

According to the present invention, a patterned light guide communicating portion is selectively provided between a light guide plate and a planar reflecting member to partially destroy a total reflection interface between an air layer and the light guide plate. Then, the propagating light in the light guide plate is introduced into the scattering reflector to cause scattering reflection, and as a result, a reflection portion corresponding to the pattern light guide communication portion is created. It is about the making method. More specifically, a novel patterned reflection characterized in that a light guide communication part mainly composed of a resin having a refractive index not much different from that of the light guide plate is partially installed between the planar reflection member and the light guide plate. It relates to the method of creating a part. For this light guide communication part, for example, a transparent resin layer is formed in a pattern on the surface of a planar reflection member such as a commercially available scattering reflection film or a white coated metal thin plate, and one side of the light guide plate is pressed or heated and pressed. It can be prepared by printing a transparent resin in a pattern on the light plate and pressing or heating the scattering reflection film. Further, when fine powder having a light diffusing property is mixed in the resin, a light scattering property can be imparted to the light guide portion, and a non-scattering specular reflection film such as a metal vapor deposition film can be used for the planar reflecting member. If the resin used for the light guide communication site has a large difference from the refractive index of the light guide plate, total light reflection occurs at the interface between the light guide plate and the light guide communication site, so effective light guide cannot be performed. A resin having a refractive index within ± 0.12 of the refractive index with respect to is selected and used. For example, vinyl chloride / vinyl acetate for paints with a refractive index of 1.52
Various general-purpose resins such as a maleic acid copolymer resin and a methyl methacrylate resin having a refractive index of 1.49 can be used.

The resin used for the light guide communicating portion is appropriately dissolved in a solvent, and in the case of a water-soluble resin or an aqueous emulsion, it is dissolved or dispersed in water.
The pattern is printed and dried in the range of microns to 50 microns. Then press it over the light guide plate,
The edge light illuminating plate provided with the light guide communicating portion of the present invention is completed by being pressed under heating as necessary. In addition to this, a solution type adhesive, an ultraviolet curable type adhesive, a hot melt type adhesive or the like can also be used as it is as a material for the light guide communicating portion, and in that case, it is not necessary to take a fresh pre-drying. Additives for inks such as colorants, various stabilizers or resin modifiers such as plasticizers, and surface tension adjusting agents can be mixed in as far as they do not impair the function of the light guide communication site. Furthermore, it is possible to add an extender pigment such as silica fine particles, talc, or calcium carbonate or titanium oxide into the light guide communication site to impart light diffusivity to the light guide communication site. However, if a large amount of pigment is mixed, the light guide plate and the planar reflection member The mixing ratio of the resin and these pigments must be kept at 1: 1 or less in volume ratio because it will hinder the adhesion with the. As the planar reflection member, white plastic film or white painted film in which commercially available air fine particles or white pigment is kneaded, laminated foil or metal thin plate, plastic film with metal deposition on mat, and white coating are applied. The metal vapor-deposited film described above can be used, and when the light guide communication portion has a light diffusing ability, a material having specular reflectivity such as a glossy metal vapor-deposited film or a metal foil can also be used. The pattern forming method of the light guide communicating portion is generally gravure printing, offset printing method or flexographic printing method when a thickness of 3 μm or less is desired, and silk screen method when a thickness of more than 3 μm is desired. The intaglio printing method is adopted. A commercially available printed circuit board laminator, office laminator, or hot press can be used to press-integrate the light guide plate and the planar reflection member with the light guide communication portion interposed. Depending on the physical properties of the resin used for the light guide communication site and the planar reflection member, the temperature, pressurization time, and pressing pressure are adjusted as appropriate, but the temperature is generally room temperature to 180 ° C., the speed is 2 cm / sec to 20 cm / sec, Pushing pressure is 0.3K per square centimeter
Satisfactory pressure integration is possible with g to 10 kg.

[0006]

The light guide communicating portion interposed between the light guide plate and the planar reflection member and having a refractive index not much different from the refractive index of the material of the light guide plate is sandwiched between the light guide plate and the planar reflection member and pressed. It is heated and pressed to form an air bubble-free interface. On the other hand, even if light with a large incident angle that is emitted from the end surface and travels through the light guide plate reaches the boundary surface between the light guide plate and the light guide communicating portion, the difference in the refractive index at the boundary is small, so total reflection is performed. Almost straightforward to enter the light guide communication site layer almost straight. Further, since there is no air layer between the light guide communicating portion and the planar reflection member, the light in the light guide plate can enter the planar reflection member without being disturbed, and the resin binding in the planar reflection member can be effectively performed. Diffuse reflection is performed at the fine interface between the agent and the pigment, or at the interface of air particles that are finely dispersed and distributed, and diffusely reflected light is returned to the light guide plate via the light guide communication site. Of the scattered light reaching the facing surface of the planar reflecting member of the light guide plate, that is, the illuminating surface, the light within the critical angle between the light guide plate and the air interface is diffused into the air from the illuminating surface and becomes effective reflected light. On the other hand, in a place where there is no light guide communication portion, an air layer is interposed between the light guide plate and the planar reflection member, and the light propagating in the light guide plate while repeating total reflection is totally reflected at the air interface and is a planar reflection member. Can't reach inside.

FIG. 1 shows the behavior of the light of the edge light surface illumination plate when there is no light guide communication part, and the light guided from the end surface of the light guide plate is totally reflected at the interface between the light guide plate and the air layer. FIG. 2 illustrates a state in which the light does not reach the planar reflection member and does not emit light to the illuminated surface. FIG. 2 shows a patterned light guide communication portion, and a book integrated with the light guide plate and the planar reflection member by pressing. Shows the behavior of the light of the edge light planar illumination plate of the invention,
It shows that only the light guide communicating portion forms an effective reflection pattern.

The edge light planar illumination plate having the light guide communication portion configured as described above receives the light guided from the end surface of the light guide plate and contains a large amount of components close to the reflection layer and is in light guide communication. In the area, the light is effectively guided to the planar reflecting member without causing total reflection and diffused reflection is made to emit the effective reflected light to the illuminated surface side, and in the area where there is no light guiding communication area, it is totally reflected at the air interface, resulting in illumination. No light is emitted to the surface. Further, the light guide communicating portion also has an effect of holding the planar reflecting member on the light guide plate, and does not require complicated assembling work of the planar reflecting member to the illumination unit.

[0009]

Example 1 Commercially available butyl methacrylate resin having a refractive index of about 1.48 (Paraloid F manufactured by Rohm and Haas Co.)
An ink was prepared by diluting 10 and 40% solution) with toluene twice, and using a silk screen original plate of 80 lines and 40%, a commercially available high reflection film with a thickness of 188 microns (ICN Japan, Melinex). (Type 339)
Printed on one side. The dot thickness after drying was 11 microns. It was stacked on a polymethylmethacrylate plate having a thickness of 4 mm and 4 cm square so that the printing surface was in contact with the plate, and a silicon rubber coating roll having a surface temperature kept at 80 degrees was pressed from both sides of the film while 20 kg of each shaft was applied. The reflective film and the acrylic plate were joined only at the portion where the printed pattern was present. When an illuminated cold cathode fluorescent tube was placed on the end surface of the acrylic light guide plate and observed from the non-bonded surface, only the bonded portion glowed, and when observed with a microscope, the dots uniformly emitted light with high brightness.

[Example 2] 10 g of vinyl chloride, vinyl acetate, maleic acid copolymer resin (Denka Vinyl 1000CS manufactured by Denki Kagaku Kogyo Co., Ltd.) for coating with a refractive index of about 1.52, dioctyl phthalate, 2 g, average particle size 6 g of 6 micron silica fine particles (Syroid S-63 manufactured by Fuji Devison Co., Ltd.)
Was dispersed and dissolved in 40 g of methyl ethyl ketone to prepare a diffusible ink. The ink of Example 1 and the diffusible ink of the present invention were applied and dried on a part of the vapor-deposited surface of a 50-micron-thick aluminum vapor-deposited polyester film to a dry thickness of 5 to 6 microns. Then, the vapor-deposited film thus coated was pressed in the same manner as in Example 1 so that the coated surface was in contact with the acrylic plate. Place a lit cold cathode fluorescent tube on the end surface of the acrylic light guide plate and observe from the non-bonded surface that only the bonded part where the diffusible ink is present shines,
When observed under a microscope, the dots uniformly emitted light with high brightness, but no reflected light emission was observed at the joint where the ink of Example 1 intervened or at the non-joint where the ink layer did not intervene.

[Example 3] A transparent coating material comprising 8 g of a saturated polyester resin having a refractive index of about 1.54 (Vylon 300, manufactured by Toyobo Co., Ltd.), 20 g of toluene and 20 g of methyl ethyl ketone was prepared. While dropping this paint into the syringe barrel and dropping it from the needle tip, the diameter after drying was applied to the coated surface of a commercially available white painted aluminum plate (Crystal White, manufactured by Sky Aluminum Co., Ltd.) with a thickness of 0.5 mm and 4 cm square. A large number of fine coatings with a thickness of approximately 0.8 mm to 2 mm and a thickness of approximately 1 to 3 microns were formed. In the same manner as in Example 1, the acrylic plate and the coating film surface were pressed so that they faced inward, and the state of reflection was observed. The bonded surface in which the fine coating film was interposed efficiently reflected and emitted light, but there was no coating film, that is, no reflection was observed at the non-bonded portion.

As described in detail above, according to the present invention, the air guide layer and the planar reflection member are partially eliminated by interposing the patterned light guide communicating portion, and the light guide communicating portion is partially eliminated. The amount of scattered reflected light is defined by the optical properties of the planar reflecting member used.
Therefore, it is possible to adjust the reflectance as desired by selecting a flat reflective member, and especially when using a flat reflective member having a high reflectance, it is easy to create a pattern of high reflectance that cannot be obtained by the conventional screen printing process. In addition to obtaining a high-intensity planar light source, it also enables the area of the pattern near the light source of the light guide plate with a large amount of incident light to be reduced, expanding the degree of freedom in the design of the light amount distribution and increasing the size of the edge. Enables the manufacture of light illumination. In addition, it is possible to avoid fluctuations in reflectance due to deterioration of the reflective ink during printing, which occurs in screen printing of the conventional method, and to improve the yield. The effect on the production process is great as it saves the labor of incorporating and fixing it in the illumination device. Further, the high brightness reduces the power consumption of the light source, reduces the thickness of the light guide plate, and enables the weight reduction of the edge light planar illumination device, which has great industrial effects.

[Brief description of drawings]

FIG. 1 shows the behavior of light in a light guide plate type planar illumination plate when there is no light guide communication site.

FIG. 2 shows a behavior of light in an edge light planar illumination plate of the present invention in which a light guide plate is partially provided and a light guide plate and a planar reflection member are integrated by pressing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Air layer 3 Planar reflection member 4 Light guide communication site 5 Introduced light 6 Reflected light 7 Illuminated surface

Claims (6)

[Claims] 1. A light guide communicating portion mainly composed of a resin having a refractive index difference of ± 0.12 or less with a refractive index of sodium of the light guide plate material between the light guide plate and the planar reflecting member. Edge light illuminating plate that is characterized by intervening in the light. 2. The edge light illuminating plate according to claim 1, wherein the thickness of the light guide communicating portion is 1 to 50 microns. 3. The edge light illuminating plate according to claim 1, wherein the light guide communicating portion contains a light scattering fine powder pigment. 4. An edge light illuminating plate, wherein the planar reflecting member according to claim 1, 2, or 3 is a scattering reflecting film or a laminated film. 5. An edge light illuminating plate, wherein the flat reflecting member according to claim 1, 2 or 3 is a white painted metal plate or foil. 6. The edge light illumination plate according to claim 3, wherein the planar reflecting member is a metal vapor deposition film.