KR101083238B1 - The plate for brightness enhancement and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a plate for improving brightness used in a backlight unit, a lighting device, or the like of a liquid crystal display, comprising: a base layer; A printed layer formed on one surface of the base layer and an air layer formed thereby; And a prism layer formed on one surface of the printed layer, wherein the printed layer has a printing height (a) of 30 µm or more, a printing width (b) of 30 to 1,000 µm, and a printing area ratio of 20 to 20% of the total area. By providing a brightness improving plate, which is characterized by being 80%, the air layer can be easily, efficiently and stably formed, and the air layer can sufficiently increase the brightness and control the total light transmittance while maintaining concealment. It is an invention that an optical device such as a backlight unit can be manufactured at low cost without laminating optical films.

Description

Plate for brightness enhancement and method of manufacturing the same

1 is a cross-sectional view showing a preferred embodiment of the present invention;

2 is a cross-sectional view showing another preferred embodiment of the present invention.

[Description of main part of drawing]

10: base material layer 20, 40: printed layer

30, 50: air layer 60: prism layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate for improving luminance used in a backlight unit, a lighting device, or the like of a liquid crystal display.

The light emitted by a backlight unit (BLU) Cold Cathode Fluorescent Lamp (CCFL), which is widely used in liquid crystal displays, passes through the light guide plate, the light diffusion plate, and the prism film in order to reach the liquid crystal panel. Let's do it. The light emitted from the light source is distributed to the front surface of the flat liquid crystal panel through the light guide plate, and the light source passed through the light guide plate can obtain a uniform light intensity across the front of the screen through the light diffusion plate, and a prism film The optical path control functions to convert light rays in various directions through the diffusion sheet into a viewing angle range suitable for an observer to recognize an image. In addition, the lower portion of the light guide plate is provided with a reflecting plate for increasing the use efficiency of the light source by allowing the light that is not delivered to the liquid crystal panel to be reflected back out of the path and used.

In addition, many kinds of plates or films are used so that the maximum amount of light generated from the light source can reach the liquid crystal device.

The light diffusion plate achieves a uniformity of brightness of the light emitted from the light source lamp and at the same time serves as a concealing role to cover the bright line of the lamp. In addition, it serves as a support for the above various optical films. To this end, various light diffusing agents are added to the light diffusing plate, which causes light diffraction, scattering, reflection, and the like, and causes a diffusion effect.

In order to collect a large amount of light from the light diffusion plate to the front, a variety of materials including a light diffusion film, a prism film should be mounted. This multi-layered material raises the cost and lowers productivity. have.

Recently, attempts have been made to reduce the application of optical films used to simplify the production process. In some cases, a prism film is adhered onto a light diffusing plate or a prism pattern is formed on the light diffusing plate. . In this case, however, it may be advantageous in terms of cost and productivity, but there is a problem that the increase in brightness is far less than expected.

Therefore, the inventors have confirmed that the luminance can be sufficiently increased while minimizing the application of optical films to improve the luminance, and have completed the present invention.

Therefore, an object of the present invention is to provide a plate for improving luminance with excellent luminance.

In addition, an object of the present invention is to provide a plate for improving brightness that can minimize the application of additional optical films included.

In addition, an object of the present invention is to provide a method of manufacturing a brightness improving plate which can easily and efficiently form an air layer.

The present invention for achieving the above object is a base layer; A printed layer formed on one surface of the base layer and an air layer formed thereby; And a prism layer formed on one surface of the printed layer, wherein the printed layer has a print height (a) of 30 μm or more, a print width (b) of 30 to 1,000 μm, and a print area ratio of 20 to 80 of the total area. It provides a brightness improving plate, characterized in that the%.

The printed layer is characterized in that a plurality of polygonal, semi-circular or semi-elliptic polyhedron shape or cross-sectional polygonal, semi-circular or semi-elliptic columnar pattern is formed in plural.

In another aspect, the present invention comprises the steps of printing by using a printing ink on a surface of the substrate layer by screen printing technique and curing to form a printed layer; And it provides a brightness improving plate manufacturing method comprising the step of forming a prism layer on one surface of the printed layer.

The print layer is characterized in that the print height (a) is 30㎛ or more, the print width (b) is 30 ~ 1,000㎛, the print area ratio is 20 to 80% of the total area.

The printing ink is a thermosetting resin or UV curable resin, characterized in that it comprises an inorganic material.

The printed layer is characterized in that a plurality of polygonal, semi-circular or semi-elliptic polyhedron shape or cross-sectional polygonal, semi-circular or semi-elliptic columnar pattern is formed in plural.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 and 2 illustrate an embodiment of the luminance-enhancing plate of the present invention, wherein the substrate layer 10 and the printed layers 20 and 40 and one air layer 30 formed on one surface of the substrate layer 10 are formed. 50 shows an example of the luminance improving plate formed.

The printing layers 20 and 40 and the air layers 30 and 50 may be formed in various ways. In the present invention, screen printing is used. One side of the substrate layer is printed using a conventional screen printing technique using printing ink, and then cured to form a printed layer.

The print layers 20 and 40 have a print height (a) of 30 μm or more, a print width (b) of 30 to 1,000 μm, and a print area ratio of 20 to 80% of the total area to obtain a brightness enhancement effect. If the printing height (a) is less than 30㎛, the volume of the air layer (30, 50) is significantly reduced when the prism layer 60 is bonded on the printed layer to reduce the effect of increasing the brightness. The higher the print height (a), the better, but technically it is difficult to manufacture more than a certain height.

The printing width b and the printing area ratio take into account the areas of the air layers 30 and 50 for effectively increasing the luminance.

The curing of the printing ink can be either thermosetting or UV curing, and thus the printing ink can use a transparent thermosetting resin or a UV curing resin, for example, any of a transparent acrylic resin, an epoxy resin or a urethane resin. . The printing ink must maintain the print height a not only after curing but also before curing so that the air layers 30 and 50 can be formed and maintained as desired. In the present invention, even if other additives are not added to maintain the pattern, it is maintained as printed even before curing.

The printing ink may further be mixed with an inorganic material. The inorganic material may help to maintain the print pattern even before curing. The inorganic material may further include 5 to 50 parts by weight with respect to 100 parts by weight of the printing ink, the usable material is preferably at least one selected from calcium carbonate, titanium oxide and silicon, the particle diameter is 1 ~ 20㎛ desirable.

The printed layers 20 and 40 may include a polygonal, semi-circular or semi-elliptic polyhedron shape or a plurality of polygonal, semi-circular or semi-elliptic columnar patterns having a plurality of cross sections.

The prism layer 60 is formed on the upper surfaces of the print layers 20 and 40 and the air layers 30 and 50 formed in this manner. For this purpose, known techniques such as coextrusion, lamination, thermal bonding, surface coating and the like can be used.

The substrate for improving the brightness is formed on the lower layer of the air layer (30, 50) due to the air layer (30, 50) formed by the printed layer (20, 40) is formed to have an uneven structure And the prism layer 60 formed on the upper surfaces of the air layers 30 and 50 are in contact only with the printing layers 20 and 40, and thus have a structure in which air flows through the air layers 30 and 50.

Conventional light diffusing plate manufacturing may have irregularities on the surface by containing light diffusing particles in order to improve brightness, but the particle size is limited in consideration of compatibility with the base resin used in the light diffusing plate. Therefore, when the prism layer was formed on the light diffusion plate, the air layers 30 and 50 were not formed even when the light diffusion particles were used as large as possible.

In the present invention, since the air layers 30 and 50 are separately formed, the luminance-enhancing plate has a relatively high density after the light diffused sufficiently in the base layer 10 passes through the air layers 30 and 50 having a relatively low density. As it moves to the in-prism layer 60, the light is effectively collected by the light recycling and light refraction, which are inherent functions of the prism layer 60, thereby improving luminance.

In addition, the present invention can produce a printed layer (20, 40) that can be maintained a significant height even before curing, it is possible to effectively form the air layer (30, 50).

Accordingly, the present invention provides a luminance improving plate that forms air layers 30 and 50 between the substrate layer 10 for diffusing light and the prism layer 60 for collecting light, and is mounted on the backlight unit. While the number of optical films can be reduced, the luminance can be improved to be equal to or greater than that in the case where the conventional light diffusing plate and the prism sheet are separately provided.

On the other hand, the composition of the base resin used for the substrate layer 10 is not particularly limited, and known base resins used in conventional light diffusion plates may be used. For example, polymethyl methacrylate resin, polystyrene resin, polycarbonate resin, styrene-acrylic copolymer resin, etc. are mentioned.

In addition, the composition of the resin used for the prism layer 60 is not particularly limited, and conventionally known resins used for a prism sheet or a prism film may be used. For example, the composition may include a mixture of a monomer or oligomer for ultraviolet polymerization and a photoinitiator.

The prism layer 60 may be a polygonal, semi-circular or semi-elliptic polyhedron in cross-section, or may have a polygonal, semi-circular or semi-elliptic columnar cross-section, and the shape may be formed in one or more types. have. Also, each structure may or may not be adjacent to each other. The prism layer 60 as described above increases the brightness by collecting the diffused light to the front part by controlling the optical path.

The brightness enhancing plate of the present invention may include a light diffusing agent, which is usually the same refractive index as the base resin, is used to increase the light diffusion rate, appropriate level of concealment, transmittance And provide diffusivity.

As the light diffusing agent, various organic and inorganic particles are used.

Representative organic particles include methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid and hydroxyethyl methacrylate. , Hydroxypropyl methacrylate, hydroxy ethyl acrylate, acrylamide, metyrol acrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate, 2-ethylhexyl acrylate, Acrylic polymer particles such as styrene, substituted styrene polymers or copolymers or terpolymers thereof; Styrenic polymer particles; Olefin polymer particles such as polyethylene and polypropylene; Copolymer particles of acryl and styrene; Copolymer particles of acryl and olefins; Styrene and olefin copolymer particles; Multi-layered multicomponent particles made by forming the particles of the homopolymer, copolymer or terpolymer and then covering the layers with other types of monomers; Siloxane-based polymer particles; Fluorine resin particles and the like.

On the other hand, examples of the inorganic light diffusing agent include calcium carbonate, barium sulfate, silicon oxide, aluminum hydroxide, titanium oxide, zirconium oxide, magnesium fluoride, talc, glass, mica and the like. Normally, the organic particles have excellent light diffusivity compared to inorganic particles, and if necessary, two or more kinds of light diffusing agents can be used in combination.

At this time, the light diffusing agent exhibits a light diffusing effect even in a small amount when the refractive index with the base resin is large, and a relatively large amount should be included when the refractive index difference is small.

In addition, if the content of the light diffusing agent is too high may cause a phenomenon that the brightness is rather deteriorated, by controlling the content of the light diffusing agent may exhibit a high brightness characteristics while showing the appropriate concealability.

In consideration of the above, the content of the light diffusing agent may be preferably 10 parts by weight or less based on 100 parts by weight of the first base resin.

And the particle diameter of the light diffusing agent may be considered 100㎛ or less.

In addition, the processing stabilizer, ultraviolet absorber, ultraviolet stabilizer, etc. may be added to the brightness improving plate of the present invention as necessary.

Although the present invention has been described with reference to the accompanying drawings, the present invention is not limited thereto, and a person skilled in the art may change the present invention without departing from the technical spirit of the present invention. Do.

Hereinafter, examples of the present invention will be described in more detail, but the scope of the present invention is not limited to these examples.

≪ Example 1 >

The print height (a) is 50 µm on one surface of a 2.0 mm thick substrate layer including 100 parts by weight of polymethyl methacrylate resin and 1 part by weight of silicone resin beads having a particle diameter of 2 μm, using a silkscreen printing technique, and a print width. A semi-elliptic pattern portion was formed by UV curing by applying acrylic resin such that (b) was 100 μm and the printing area ratio was 20% of the total area.

An acrylate oligomer (refractive index: 1.57) was applied to the upper surface of the printing layer to bond a film formed by forming a triangular pattern (base: 50 μm, height: 25 μm) by UV curing to prepare a plate for improving brightness.

<Example 2>

Except that the printing height (a) of 30 ㎛ in Example 1 was prepared in the same manner as to improve the brightness plate.

<Example 3>

Except for changing the printing width (b) to 30㎛ in Example 1 was prepared a plate for improving brightness.

<Example 4>

Except for changing the printing width (b) to 1000㎛ in Example 1 was prepared a plate for improving brightness.

Example 5

Except for changing the printing area ratio of 80% in Example 1, a brightness improving plate was manufactured in the same manner.

Comparative Example 1

Except for changing the print height (a) to 20㎛ in Example 1 was prepared a plate for improving brightness.

Comparative Example 2

Except for changing the printing width (b) to 1100㎛ in Example 1 was prepared a plate for improving brightness.

Comparative Example 3

Except for changing the print area ratio of 19% in Example 1, a plate for improving brightness was manufactured.

<Comparative Example 4>

Except for changing the print area ratio of 81% in Example 1 was prepared a plate for improving brightness.

Comparative Example 5

A triangular pattern was obtained by UV curing by applying an acrylate oligomer (refractive index: 1.57) to the upper surface of the 2.0 mm thick substrate layer including 100 parts by weight of polymethyl methacrylate resin and 1 part by weight of silicone resin beads having a particle diameter of 2 μm. 50 μm, height: 25 μm) was laminated to prepare a plate for improving luminance.

The luminance and visual stain test was performed on the luminance improving plate manufactured in the above example in the following manner, and the results are shown in the following [Table 1].

(1) luminance

Luminance was measured after the backlight was turned on using Topcon's BM-7, a diffuser plate was put on, and preheated for 2 hours. The luminance value of the luminance enhancing plates produced by the above Examples and Comparative Examples was measured in terms of the luminance increase (without the liquid crystal panel) when the diffuser plate of RM714 was used.

(2) visual stain inspection

Visual staining was visually evaluated while the LCD panel was put on and operated after assembly of the backlight unit (BLU). When staining was not seen, it was marked as good and staining was marked as bad.

division Printing height (㎛) Print Width (㎛) Print Area Ratio (%) Luminance (%) Visual stain test Example 1 50 100 20 54 Good Example 2 30 100 20 53 Good Example 3 50 30 20 54 Good Example 4 50 1000 20 51 Good Example 5 50 100 80 50 Good Comparative Example 1 20 100 20 15 Good Comparative Example 2 50 1100 20 50 Bad Comparative Example 3 50 100 19 34 Good Comparative Example 4 50 100 81 37 Good Comparative Example 5 - - - 2 Good

As a result of the physical property evaluation, the embodiments of the present invention showed a high luminance increase rate, and the stain did not appear. Accordingly, it can be seen that there is no significant difference in luminance when there is a certain level of air layer.

However, in Comparative Example 1, where the printing height is too low, the area of the air layer is significantly reduced, and thus the luminance increase rate is low. In addition, in Comparative Example 2 in which the printing width is too large, the light unevenness increases, and thus, the luminance spot is increased.

On the other hand, in Comparative Example 4, where the print area ratio is too high, the ratio of the air layer becomes too low, so that the increase in luminance is not sufficient. It can also be seen that the brightness increase is not efficient.

As described above, the present invention can easily and efficiently and stably form the air layer can provide a plate with a sufficiently high brightness can minimize the need to provide an optical film for the additional brightness enhancement.

The present invention minimizes the necessity of additionally providing additional light diffusing films or prism sheets for doubling luminance by providing a plate having sufficiently high luminance and a method of manufacturing the same, so that an optical device such as a backlight unit can be manufactured at low cost.

Claims (7)

A base layer; A printed layer formed on one surface of the base layer and an air layer formed thereby; And A prism layer formed on one surface of the printed layer, The printing layer has a print height (a) of 30㎛ or more, a print width (b) of 30 ~ 1,000㎛, the print area ratio, characterized in that the print area ratio of 20 to 80% of the total area. The method of claim 1, The printing layer has a polygonal, semi-circular or semi-elliptic polyhedron or cross-sectional polygonal, semi-circular or semi-elliptic columnar pattern is formed with a plurality of brightness enhancement plate, characterized in that. Printing on one surface of the substrate layer by using a screen printing technique and then curing to form a printed layer; And Forming a prism layer on one surface of the printed layer, The printing layer has a printing height of 30㎛ or more, a printing width of 30 ~ 1,000㎛, print area ratio of 20 to 80% of the total area of the manufacturing method of the brightness enhancement plate. delete The method of claim 3, wherein The printing ink is a brightness-enhancing plate manufacturing method, characterized in that the thermosetting resin or UV curable resin. The method of claim 3, wherein The printing ink is a brightness improving plate manufacturing method comprising an inorganic material. The method of claim 3, wherein The printing layer has a polygonal, semi-circular or semi-elliptic polyhedron shape or a cross-sectional polygonal, semi-circular or semi-elliptic columnar pattern is formed in a plurality of methods for producing a brightness plate.

Images