WO2011130948A1

WO2011130948A1 - Diffusion plate for backlight module

Info

Publication number: WO2011130948A1
Application number: PCT/CN2010/074879
Authority: WO
Inventors: 金长松; 金青松
Original assignee: 上海凯鑫森产业投资控股有限公司
Priority date: 2010-04-23
Filing date: 2010-07-02
Publication date: 2011-10-27
Also published as: CN101840103B; CN101840103A

Abstract

A diffusion plate (20) for backlight module includes a base material layer (21) made of light transmission material, and a diffusion layer (22) stacked on the base material layer. The diffusion layer includes adhesive agent (22c), nano-particles (22b), and micro-particles (22a). The diffusion plate of this structure can improve the rigidity of the diffusion layer and prevent the diffusion layer from twisting or bending.

Description

Diffusion sheet for backlight module

The present application claims priority to Chinese Patent Application No. 201010160656. filed on Apr. 23, 2010, the entire disclosure of which is incorporated herein by reference. In this application.

Technical field

The present invention relates to the field of liquid crystal displays, and more particularly to a diffusion sheet for a backlight module. Background technique

In general, in order to improve the back surface of liquid crystal displays (LCDs) including not only electronic illuminating panels, notebook computers, word processors, desktop computer monitors, televisions, video cameras, but also automotive and aircraft displays. For the brightness of the flat panel display, a backlight module of various structures is provided. The backlight module includes a light source, a light guide plate and a plurality of optical sheets, and the light from the light source passes through the light guide plate and the plurality of optical sheets and then exits to the display.

FIG. 1 is a schematic diagram of a conventional backlight module. As shown in FIG. 1, the backlight module includes: a light source 4; a light guide plate 5 for changing a path of light emitted from the light source 4 to be guided to a display portion (not shown); and a plurality of optical sheets 6, 7, 8 Provided between the light guide plate 5 and the display portion (not shown) for improving the efficiency of emitting light from the light guide plate 5; the reflector 2 is provided to prevent the light generated from the light source 4 from being exposed to the outside The lower portion of the light guide plate 5, the light source reflector 3, and the mold frame 1 are formed by sequentially laminating the reflector 2, the light source reflector 3, the light guide plate 5, and the optical sheets 6, 7, and 8 on the mold frame 1.

In the manufacturing process, the optical sheets 6, 7, 8 may be composed of the diffusion sheet 6, the prism sheet 7, and the protective sheet 8, and the diffusion sheet 6 functions to diffuse and diffuse from the light guide plate 5 and enter the display portion (not shown). The light is made to make the brightness distribution of the light uniform. The prism sheet 7 is repeatedly formed on the upper portion to have a sectional shape of The triangular prisms condense the light diffused through the diffusion sheet 6 to a direction perpendicular to the plane of the display portion (not shown) to increase the brightness.

Therefore, most of the light passing through the prism sheet 7 is vertically advanced with respect to the plane of the display portion (not shown), thereby having a uniform luminance distribution. Further, the protective sheet 8 is laminated on the upper portion of the prism sheet 7, and the light incident on the prism sheet 7 is diffused while protecting the surface of the prism sheet 7, so that the distribution of light is made uniform.

With the recent trend toward reduction in weight, ultra-thinness, and high brightness of liquid crystal display devices, the use of LED lamps has been increasing. Therefore, it is necessary to obtain a diffusion sheet having a diffusion effect without a loss of brightness while concealing the lamp arrangement pattern.

For this reason, in the prior art, a diffusion sheet coated with fine particles is used, but although these fine particles have a certain diffusion effect, if the concealing effect is increased, the amount of the fine particles in the diffusion sheet and the amount of the diffusion layer are increased. The concealing effect is improved by the increase of the haze, but the coating is difficult, and the loss of brightness is caused by the decrease of the relative transmittance. Therefore, the prior art cannot achieve the effect of concealing the LED lamp arrangement mode and low luminance loss. .

Korean Patent No. 10-0938118, which provides an optical sheet module for improving light brightness by improving light utilization efficiency, comprising: a nanowire comprising a transparent film, a grooved nanostructure formed on one side of the transparent film, and formed on a metal layer on the nanostructure; and at least one optical sheet disposed on the polarizer, the nanowire, and the lower portion of the polarizer. This technology is only suitable for polarizers and is achieved by special nano-coating techniques, which are difficult to apply.

In addition, Japanese Patent No. 7,160,018 discloses a backlight system in which a nanoparticle layer is formed on a fine structure surface of a light guide plate. This patent attempts to improve the brightness of light supplied to a liquid crystal display device by a nanoparticle layer on the surface of the light guide plate. A problem with this prior art is that it is difficult to uniformly apply the nanoparticle layer to the surface of the light guide plate of the hard material, which requires chemical deposition or the like.

In other prior art, it is limited to providing the nanoparticles to the inside of the light guide plate or the inside of the fine structure face of the prism, and therefore, there is still a problem of easy scratching due to contact between the other optical sheets and the protective sheets. Therefore, it is necessary to obtain a diffusion sheet having a uniform diffusion effect while preserving the transmittance, increasing the haze, reducing the luminance loss, and improving the concealability.

Summary of the invention

Accordingly, it is an object of the present invention to overcome the deficiencies of the prior art and to provide a diffuser for a backlight module that reduces rigidity, conceals or offsets flaws in the upper portion of the diffuser, and is rigid and ultra-thin. Lightness is improved.

In order to achieve the above object, the present invention provides a diffusion sheet for a backlight module, comprising: a substrate layer composed of a light transmissive material; and a diffusion layer laminated on the upper portion of the substrate layer and containing an adhesive, nanoparticles, and fine particles.

According to a preferred feature of the invention, the diffusion layer has a thickness of from 1 m to 30 μm.

According to a preferred feature of the invention, the microparticles comprise at least one of an acrylic resin, an acrylonitrile resin, a polyurethane, a polyvinyl chloride, a polystyrene, a polyacrylonitrile or a polyimide.

According to a preferred feature of the invention, the microparticles are composed of polymethyl methacrylate, and the microparticles have a particle size of 5 μm to 25 μm.

According to a preferred feature of the invention, the nanoparticles comprise at least one of silicon dioxide, alumina, titania, zirconia, aluminum hydroxide, barium sulfide or magnesium silicate, and mixtures of the foregoing.

According to a preferred feature of the invention, the nanoparticles are composed of silicon dioxide, and the nanoparticles have a particle diameter of 10 nm to 100 nm.

According to a preferred feature of the present invention, the content of the fine particles and the nanoparticles of the diffusion layer is 40 to 200 parts by weight of the fine particles and 5 to 50 parts by weight of the nanoparticles with respect to 100 parts by weight of the adhesive.

In the diffusion sheet for a backlight module of the embodiment of the present invention, an acrylic resin or a hardening adhesive having excellent optical properties and elasticity is used in a diffusion layer laminated on the upper portion of the substrate layer and containing nanoparticles and fine particles, thereby improving the diffusion layer. Rigid, prevents distortion or curling of the diffuser. Further, according to the content of the nanoparticles in the diffusion layer, it has an excellent diffusion effect, and it is possible to effectively conceal or offset the defects of the light guide plate and the optical sheet while preventing the luminance loss. DRAWINGS

The drawings described herein are provided to provide a further understanding of the invention, and are not intended to limit the invention. In the drawing:

1 is a schematic diagram of a backlight module in the prior art;

Figure 2 is a transverse cross-sectional view of a diffusion sheet according to an embodiment of the present invention;

Fig. 3 is a schematic process view for producing a diffusion sheet of an embodiment of the present invention.

Figure symbol

1: Formwork 3: Light source reflector

5: Light guide plate 7: Prism sheet

20: Diffusion sheet 22: Diffusion layer

22b: Nanoparticles 30: Pulling the stick

2: reflector 4: light source

6: Diffuser 8: Protective sheet

2 1: Substrate layer 22a: Microparticles

22c : Adhesive 40: Winding stick

1, 42, 5 1, 52: Transfer roller 50: Diffusion coating module 60: Drying module 70: UV curing module

In order to make the objects, technical solutions, and advantages of the present invention more comprehensible, the specific embodiments of the present invention will be described in detail below. The illustrative embodiments of the present invention and the description thereof are intended to illustrate the invention, but are not intended to limit the invention.

2 is a transverse cross-sectional view of a diffusion sheet according to an embodiment of the present invention, and FIG. 3 is an embodiment of manufacturing the present invention. A schematic process diagram of a diffusion sheet.

As shown in FIG. 2, the diffusion sheet 20 of the present invention may include a substrate layer 21 and a diffusion layer 22.

The base layer 21 functions to transmit incident light from the lower portion to the upper portion, and is made of a translucent material such as a transparent synthetic resin for efficiently transmitting light.

The above transparent synthetic resin includes, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene, polycarbonate, polyester (Polyester) ) A plastic film prepared, but not limited. For example, C0SM0SHINE sold by Japan T0Y0B0 company, LUMILAR of T0RAY company, or the like can be used as the above-mentioned base material layer 21.

Preferably, among the transparent synthetic resins, a polyester fiber-based polymer such as polyethylene terephthalate or polyethylene naphthalate has better transparency and strength.

Further, preferably, the transparent synthetic resin may be used in combination of one or more kinds, and in order to improve heat resistance and weather resistance, a crosslinking agent, an antioxidant, a light stabilizer, a filler, a reinforcing fiber, a reinforcing agent, and an anti-proof agent may be added. Electrostatic agents, flame retardants, plasticizers, anti-deterioration agents and other additives.

The thickness of the substrate layer 21 is required to satisfy both the thickness which can be set in the display device and the thickness sufficient to resist bending. Preferably, the substrate layer 21 has a thickness of about ΙΟΟ μ ηι to 250 μ ηι. When the content is more than the above range, the brightness is lowered, and the problem of the lightness and thinness of the display device cannot be satisfied. If the diffusion layer 22 is laminated on the upper portion of the base material layer, the distortion may occur and the operation may be difficult.

Preferably, the diffusion sheet 20 of the present invention has a refractive index of 0. 05 or less, preferably 0.01 or less, more preferably 0.55 or less in-plane and out-of-plane birefringence, thereby preventing polarization rotation.

The diffusion layer 22 of the present invention is laminated on the upper portion of the substrate layer, and contains the adhesive 22c, the nanoparticles 22b and the fine particles 22a dispersed in the adhesive. The thickness of the diffusion layer 22 is not particularly limited, and is preferably Ι. The thickness of μ ιη to 30 μ ιη.

The microparticles 22a may be one or more selected from the group consisting of acrylic resin, acrylonitrile resin, polyurethane, polyvinyl chloride, polystyrene, polyacrylonitrile, and polyimide, and it is preferred to use an acrylic resin having high transparency during curing. More preferably, polymethyl methacrylate (PMMA) is used.

The microparticles 22a have the same size, or any size between each other, and can be variously Arrange. The distance between the microparticles may be different, and may be arranged in contact or in a very close proximity, and the distance between the microparticles is at most about 10 μm. Additionally, the microparticles can be laterally offset at an angle to each other. Coating can be made more convenient by the above spacing and angled offset.

The size of the microparticles 22a is preferably 5 μ ηι to 25 μηη. If it exceeds the above range, the concealing effect is enhanced by the increase in haze, but the coating is difficult, and the transmittance is relatively reduced, resulting in loss of brightness. However, if it is less than the above range, the concealing effect is lowered.

In the diffusion layer 22, the content of the above fine particles 22a is preferably 40 to 200 parts by weight based on 100 parts by weight of the adhesive 22c. If it exceeds the above range, the fixation of the fine particles 22a is difficult, and if it is less than the above range, the diffusion effect is lowered.

The nanoparticles 22b may use one or more of silica, alumina, titania, zirconia, aluminum hydroxide, barium sulfide or magnesium silicate, or a mixture of the above, and preferably, it is easily used. Nano-level particles, which have low light shielding properties, have good dispersibility, and contribute to heat resistance and rigidity of silica.

The shape of the nanoparticles 22b may be any shape such as a spherical shape, a spindle shape, a plate shape, or a fiber shape. However, in order to reduce the shielding property of light, a spherical shape is preferable.

The size of the nanoparticles 22b, preferably having a particle diameter of 10 nm to 100 nm. When it exceeds the above range, the light shielding property is lowered by the influence of the short wavelength, and the luminance is lowered. If the range is less than the above range, the surface energy of the nanoparticle 22b rises to cause aggregation.

The light passing through the diffusion layer 22 is scattered by the above-mentioned fine particles 22a and 22b, thereby effectively concealing or canceling the dark spots which can be observed when the flaws are present in the diffusion sheet 20.

In the diffusion layer 22, the content of the nanoparticles 22b is preferably 5 to 50 parts by weight relative to 100 parts by weight of the adhesive 22c. When the content of the nanoparticles 22b is less than 5 parts by weight, the diffusibility and rigidity are not preferable, and if it exceeds 50 parts by weight, the diffusibility and rigidity are improved, but the luminance is lost.

The adhesive 22c constituting the diffusion layer 22 may be selected from polycarbonate (Polycarbonate, PC), polyethylene terephthalate (PET), polyacrylate (PAR), urethaneacrylate (UA). , polyetherimide (PEI), polynaphthalene Preferably, at least one of polyethyelenermapthalate (PEN), polyphenylene sulfide (PSS), polyarylate (polyarylate), and polyimide is used, and preferably, Made of a polyacrylate resin or urethane acrylate having excellent elasticity, it contributes to improving the water repellency, the twist resistance, and the uniform dispersibility of the nanoparticles 22b of the adhesive 22c.

Further, it is preferable that the above-mentioned adhesive 22c further contains a curing agent such as a polyisocyanate compound, and by including these curing agents, a cationic antistatic agent having an excellent antistatic effect is added even in order to stably disperse the nanoparticles 22b. It can also compensate for the problem of a decrease in the rate of hardening reaction.

As shown in FIG. 3, preferably, the manufacturing process of the diffusion sheet 20 of the present invention can be performed by a stretching roll 30, a winding roll 40, a plurality of transfer rolls 41, 42, 51, 52, and a diffusion coating comprising the nanoparticles 22b. The module 50, the drying module 60, and the ultraviolet curing module 70 are completed.

The stretching roller 30 stretches the substrate layer 21, and the winding roller 40 is wound around the substrate layer 21 which forms the diffusion layer 22.

The plurality of transfer rollers 41, 42 are transferred to the substrate layer 21 which is cured by the diffusion layer 22 via the drying module 60 and the ultraviolet curing module 70.

The diffusion coating module 50 is provided with an adhesive 22c which mixes the fine particles 22a, the nanoparticles 22b and a volatile solvent, and the solvent includes methanol, ethanol, n-propanol, ISO propanol, n-butanol, and ISO butanol. The alcohol may also include ketones such as methyl ethyl ketone (Methyl Ethyl Keton) and MIBK (Methyl Isobutyl Ketone, MIBK).

Further, the adhesive 22c may further include a dispersion stabilizer containing a surfactant such as a cationic system, an anionic system, a nonionic surfactant or a fluorine-based surfactant in order to improve the dispersibility of the fine particles, and preferably includes the adhesive including light. Polymerization initiator.

In the present invention, the method of applying the desired fine particles 22a and the dispersion of the nanoparticles 22b to the diffusion layer 22 is not particularly limited as long as the method of uniform coating can be completed. Various coating methods including a general gravure coating method, a wire drawing method, a spray coating method, a micro gravure coating method, a slit coating method, and the like can be used. Further, a coating method such as a discharge method such as an inkjet method or a screen printing method can be used as needed. After the diffusion layer 22 is applied by the diffusion coating module 50, it is hardened by the drying module 60 and the ultraviolet curing module 70, and is wound and stored by the winding roller 40.

The diffusion sheet 20 of the present invention can be manufactured by the above-described manufacturing process, and the diffusion sheet 20 of the present invention thus manufactured can reduce the brightness loss, improve the effect of concealing or offset the flaw exposed to the upper portion of the diffusion sheet, and has an improvement. Its rigidity, ultra-thinness and light weight.

The specific embodiments of the present invention have been described in detail with reference to the preferred embodiments of the present invention. The scope of the invention, any modifications, equivalents, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

Claim

A diffusion sheet for a backlight module, characterized in that the diffusion sheet comprises: a substrate layer composed of a light transmissive material; and a diffusion layer laminated on the upper portion of the substrate layer and containing an adhesive , nanoparticles and microparticles.

The diffusion sheet for a backlight module according to claim 1, wherein the diffusion layer has a thickness of from Ιμηη to 30μηι.

The diffusion sheet for a backlight module according to claim 1, wherein the microparticles comprise an acrylic resin, an acrylonitrile resin, a polyurethane, a polyvinyl chloride, a polystyrene, a polyacrylonitrile or a polyacyl group. At least one of the imines is composed.

The diffusion sheet for a backlight module according to claim 1, wherein the fine particles are composed of polymethyl methacrylate, and the fine particles have a particle diameter of 5 μm to 25 μm.

The diffusion sheet for a backlight module according to claim 1, wherein the nanoparticles comprise at least one of silica, alumina, titania, zirconia, and aluminum hydroxide. , barium sulfide or magnesium silicate, and mixtures of the foregoing.

The diffusion sheet for a backlight module according to claim 1, wherein the nanoparticles are composed of silicon dioxide, and the nanoparticles have a particle diameter of 10 nm to 100 nm.

The diffusion sheet for a backlight module according to claim 1, wherein: the content of the microparticles and the nanoparticles in the diffusion layer is 40 to 200 microparticles per 100 parts by weight of the adhesive. Parts by weight and nanoparticles 5 to 50 parts by weight.