KR20100112830A - Method of preparing light diffusion sheet - Google Patents

Abstract

PURPOSE: The manufacturing method of the light diffusion sheet has the high brightness and the excellent light diffusion efficiency. CONSTITUTION: It spreads the ink for the light diffusing layer formation to the screen printing method and the light diffusing layer(10) is formed. The ink for the light diffusing layer formation comprises the binder region at the upper part of the reflecting layer(20) and glass bead(11).

Description

Method of preparing light diffusion sheet {Method of preparing light diffusion sheet}

The present invention relates to a method for manufacturing a light diffusion sheet, and more particularly, to a method for manufacturing a light diffusion sheet having a rectangular glass bead and manufactured by screen printing.

In general, the light diffusion sheet is widely used in LCD devices that are used in a variety of LCD monitors, notebooks, LCD TVs, mobile phones, camcorders, digital cameras, PDAs. In addition, as the LED light source is widely used in recent years, in addition to the backlighting unit of the electronic products as described above, the use range of various signs such as the trend is gradually increasing.

The light diffusion layer used in the light diffusion sheet has a form in which glass beads for refracting and scattering light are dispersed on a binder resin, and the reflection layer reflects light so that light does not leak in an unnecessary direction and is usually white. It is formed from pigments or through mirror layer deposition.

The light diffusion layer is a key to uniformly diffuse light while maintaining high brightness, but many studies have been conducted on the type of binder resin and the method of dispersing glass beads. There is still a need for a light diffusing sheet having a diffusing performance and high luminance.

An object of the present invention is to provide a method of manufacturing a light diffusion sheet having high brightness and excellent light diffusion performance.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the manufacturing method of the light-diffusion sheet provided with the reflecting layer and the light-diffusion layer which concerns on this invention screens the light-diffusion layer forming ink in which the said light-diffusion layer contains binder resin and rectangular glass beads on the said reflection layer. It is characterized by being formed by coating in a printing method.

In addition, another manufacturing method of the light diffusion sheet of the present invention for solving the above problems is a method of manufacturing a light diffusion sheet comprising a reflective layer, a lower light diffusion layer and a light guide layer, wherein the lower light diffusion layer is a binder in the light guide layer. It is characterized by being formed by applying a screen printing method to the ink for forming the lower light diffusion layer comprising a resin and a rectangular glass bead.

In the present invention, the light diffusion layer may further include a spherical glass bead in addition to the rectangular glass bead.

In addition, in the present invention, the light diffusion sheet including the light guide layer may further include a light diffusion layer on the light guide layer.

Since the light diffusing sheet manufactured according to the manufacturing method of the present invention has high brightness, sufficient brightness is ensured even if the number of light sources is reduced, thereby enabling a more economical device configuration.

In addition, the light diffusing sheet produced according to the manufacturing method of the present invention has excellent light diffusing performance. Therefore, it is possible not only to maintain uniform brightness throughout the sheet, but also to prevent glare that is a problem when using an LED light source.

In addition, since the manufacturing method of the present invention uses a screen printing method, it is possible to form a variety of fine patterns in the light diffusion layer. Therefore, it is possible not only to increase the economic value by imparting aesthetic characteristics, but also to have an effect of adjusting the emitted light to the required form.

Hereinafter, the present invention will be described in detail with reference to the drawings. The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

The production method of the present invention is characterized by using a screen printing method in the production of the light diffusion layer of the light diffusion sheet. As described above, the light diffusing layer includes a binder resin and glass beads. In the related art, the light diffusing layer is manufactured mainly by extrusion or injection, but there is a high possibility that the glass bead may damage the device.

However, the screen printing method can not only form the light diffusion layer in a method simpler than extrusion or injection, but also rarely damage the device by glass beads. In addition, the screen printing method may be used to manufacture a light diffusion layer having various fine shapes and patterns, thereby increasing light diffusion performance and providing various visual functional effects. For example, not only the amount of light emitted may be adjusted by adjusting the shape and size of the pattern, but the shape of the visible pattern may vary depending on the viewing position, or a pattern may be formed in which the amount of light varies. It is also possible to print inks different in composition for each print area.

Further, in the manufacturing method of the present invention, the light diffusion layer forming ink for screen printing is characterized in that it comprises a rectangular glass bead. Conventionally, a spherical glass bead has been used for the light diffusion layer, but the spherical glass bead does not have sufficient light scattering effect and has a problem that light is concentrated and reflected in some directions, particularly in a direction in which light is incident. However, since the rectangular glass bead according to the present invention has a rectangular shape, the reflection on the surface of the glass bead and the refraction of light in the interior are made in various directions. Not only can it show uniform brightness, but also the brightness of a diffusion sheet is improved.

The specific shape of the rectangular glass beads according to the present invention is not particularly limited as long as it can scatter light in various directions. The method of manufacturing the square glass beads may be prepared by, for example, grinding the manufactured glass beads or spherical glass beads, but is not limited thereto.

Hereinafter, an embodiment of the manufacturing method according to the present invention will be described in detail.

The reflective layer according to the present invention may be applied without limitation to the reflective layer forming method used in the art. For example, a white ink may be coated to be dried, or may be formed by depositing a mirror layer, but is not limited thereto.

The light diffusing layer according to the present invention can be produced by screen printing an ink for forming a light diffusing layer. As the binder resin used in the light diffusion layer forming ink, any transparent resin commonly used in the light diffusion plate may be used without particular limitation. For example, an acrylic resin such as PMMA, a polycarbonate resin, an epoxy resin, or the like may be used, but is not limited thereto.

The light diffusing layer forming ink may be prepared by mixing the angular glass beads with a liquid binder resin dissolved in a suitable solvent. For example, 20 to 70 wt% of a liquid binder resin dissolved in a suitable solvent and a rectangular glass It can be prepared to contain 30 to 80% by weight of beads. When the content of the rectangular glass beads is less than 30% by weight, the brightness and the light scattering performance may be lowered. When the content of the angled glass beads is greater than 80% by weight, the adhesion of the light diffusion layer may be lowered.

1 schematically shows an embodiment of a light diffusion sheet formed according to the manufacturing method of the present invention. 1 shows a light diffusion sheet used when the light source 100 is present on the front or side of the diffusion sheet. The light diffusion sheet according to the present invention includes a light diffusion layer 10 and a reflection layer 20, and the light diffusion layer 10 includes a rectangular glass bead 11.

In another embodiment of the present invention, the light diffusion layer 20 may further include spherical glass beads in addition to the rectangular glass beads. When the spherical glass beads are further added to the light diffusing layer forming ink and screen printed, the light diffusing layer 10 including both the rectangular glass beads and the spherical glass beads can be obtained. By mixing the glass beads, the brightness of the light diffusion sheet may be increased through the interference effect of the scattered light. The mixing ratio of the rectangular glass beads and the spherical glass beads may be adopted within a range not departing from the scope of the present invention. For example, the rectangular glass beads may have a mixing weight ratio of spherical glass beads = 1: 0.1 to 2, but is not limited thereto. It doesn't happen.

In another embodiment of the present invention, a method of manufacturing a light diffusion sheet further comprising a light guide layer on the light diffusion layer. In the art, a light diffusion sheet having a light diffusion layer below the light guide layer, or each of the upper and lower portions thereof is widely used, and an embodiment of the present invention is for forming the light diffusion layer of the present invention described above under the light guide layer. Ink is screen printed to have a lower light diffusing layer. For example, an acrylic resin such as PMMA, a polycarbonate resin, an epoxy resin, or the like, which is a transparent resin commonly used for a light diffusion sheet, may be used as the light guide layer. When the light guide layer is prepared, the light diffusion layer forming ink including the above-described binder resin and the rectangular glass beads is coated and dried to form a lower light diffusion layer, and the above-described conventional reflective layer is applied to the lower light diffusion layer. It can form and manufacture a light-diffusion sheet. By providing a transparent light guide layer on the light diffusing layer, the light diffusing sheet according to the present invention may be used even when the light source is present on the rear surface in addition to the case where the light source is present on the front or side of the light diffusing sheet.

Also, optionally, in the manufacturing method of the present invention, the method may further include forming a light diffusion layer on the light guide layer. FIG. 2 shows a light diffusion sheet having a light diffusion layer 10 and a reflection layer 20 below and a second light diffusion layer 40 above the light guide layer 30. In addition, as shown in FIG. 3, when the light source 100 is present at the bottom, the reflective layer 20 is not formed at a portion where light is incident.

Optionally, in one embodiment of the present invention, the lower light diffusing layer forming ink may further include a spherical glass bead as described above, thereby increasing the brightness of the light diffusing sheet.

Optionally, in another embodiment of the present invention, the upper light diffusing layer 40 may be coated with a screen printing method of forming an upper light diffusing layer ink including a binder resin and a rectangular glass bead similarly to the lower light diffusing layer 10. Can be formed.

In addition, when the upper light diffusing layer 40 includes a rectangular glass bead, when the light source is located below the light diffusing layer, a portion corresponding to the position of the light source in the light diffusing sheet has a greater amount of light than other portions, resulting in uneven overall sheet. Luminance may appear. Therefore, optionally, in another embodiment of the present invention, in order to obtain a uniform light diffusing effect throughout the sheet, the upper light diffusing layer includes a dot pattern with an upper light diffusing layer forming ink including a rectangular glass bead only at a portion corresponding to the position of the light source. It may be formed by applying a screen printing method to be provided. In this case, depending on the type of light source and the specific use of the light diffusion sheet, the size of the dot pattern, the content of the rectangular glass beads, etc. may be appropriately adopted. In addition, a portion that does not correspond to the position of the light source may be coated with a transparent ink that does not form an upper light diffusion layer or does not include glass beads.

Optionally, as shown in FIG. 4, in another embodiment of the present invention, the upper light diffusion layer 40 may be formed by screen printing using the ink for forming the upper light diffusion layer in a pattern in which a plurality of convex lens shapes are distributed on a plane. It can be formed by application. When the upper diffusion layer 40 has a plurality of convex lens-shaped patterns, light condensation may be improved to increase brightness of the light diffusion sheet. When the brightness of the light diffusion sheet is increased, the number of light sources can be reduced, thereby enabling a more economical device configuration. The convex lens shape may be appropriately determined according to a specific use of the light diffusion sheet, and may be, for example, 20 to 3000 microns, but is not limited thereto.

Optionally, in another embodiment of the present invention, the upper light diffusing layer forming ink may be applied by screen printing several times so that the convex lens-shaped pattern is formed in a multilayer. If the convex lens-like pattern is composed of multiple layers, the straightness of the light emitted from the light diffusion sheet can be further improved.

Further, if necessary according to the specific use of the light diffusion sheet, the plurality of convex lens-shaped patterns may be screen printed to have different colors depending on the area. Accordingly, even using only a white light source, it is possible to emit light of various colors, thereby enabling a simpler light emitting device configuration.

Optionally, as shown in FIG. 5, in another embodiment of the present invention, when the light source 100 exists under the reflective layer 20, the upper light diffusion layer 40 corresponds to the position of the light source 100. The part is a convex lens shape having a diameter larger than the diameter of the light source, the portion that does not correspond to the position of the light source 100 is a pattern in which a plurality of convex lenses having a diameter smaller than the diameter of the light source 100 is distributed It can be formed by applying the ink for forming the upper light diffusion layer by screen printing method to have a.

Also optionally, as shown in FIG. 6, in another embodiment of the present invention, the binder resin and the rectangular glass on the side not facing the light source 100 of the light diffusion sheet including or not including the light diffusion layer on the light guide layer. The side light diffusion layer 50 including the beads and the reflective layer 60 may be further formed outside the side light diffusion layer. When the light diffusion layer 50 and the reflection layer 60 according to the present invention are further provided on the side of the light diffusion sheet, not only can the loss of light emitted to the side be prevented, but also the amount of light emitted to the top of the light diffusion sheet. Since this increases, the brightness of the light diffusion sheet can be increased. As the method of manufacturing the side light diffusion layer 50 and the side reflection layer 60, an ink coating method that is commonly used, such as screen printing and spray injection, may be applied.

In addition, as shown in FIG. 7, the light diffusion layer 10 may be screen-printed with ink containing a binder resin and a spherical glass bead 12 at a boundary of a region requiring high brightness, and may have high brightness inside the boundary. The region may be formed by screen printing with an ink comprising a binder resin and a rectangular glass bead 11. As described above, since the spherical glass beads have a large amount of light returning back to the direction in which light is incident, the spherical glass beads are formed by screen printing the ink of the spherical glass beads, and forming a boundary portion of the specific region. When the area is formed by screen printing with ink containing a rectangular glass bead, the light incident on the boundary part among the light scattered in the specific area is returned to the specific solution, and thus the specific area may exhibit higher luminance than other areas. Will be.

The ink for forming the light diffusion layer used in the present invention may further include various additives within a range not departing from the scope of the present invention. For example, an antifoaming agent, a leveling agent, a diluent, a drying retardant, and the like may be used in an appropriate amount as necessary, but is not limited thereto.

In the above, embodiments have been described in detail with reference to the drawings in order to explain the present invention in detail. However, embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the above-described embodiments. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The following drawings, which are attached to this specification, illustrate preferred embodiments of the present invention, and together with the contents of the present invention serve to further understand the technical spirit of the present invention, the present invention is limited to the matters described in such drawings. It should not be construed as limited.

1 is a schematic cross-sectional view of a light diffusion sheet for side or front light source manufactured according to an embodiment of the present invention.

2 is a schematic cross-sectional view of a light diffusion sheet for a side or front light source having a light guide layer and an upper light diffusion layer manufactured according to another embodiment of the present invention.

3 is a schematic cross-sectional view of a light diffusion sheet for a rear light source further comprising a light guide layer and an upper light diffusion layer, prepared according to another embodiment of the present invention.

4 is a schematic cross-sectional view of a light diffusing sheet manufactured according to another embodiment of the present invention and having an upper light diffusing layer having a plurality of convex lens-shaped patterns.

5 is manufactured according to another embodiment of the present invention, and includes a plurality of convex lens shapes, the convex lens shape corresponding to the light source has a light having an upper light diffusing layer having a pattern larger than that of the convex lens of another position. A schematic cross sectional view of a diffusion sheet.

6 is a schematic cross-sectional view of a light diffusing sheet manufactured according to another embodiment of the present invention and having a light diffusing layer and a reflecting layer on the side of the sheet.

FIG. 7 is a schematic cross-sectional view of a light diffusing sheet manufactured according to another embodiment of the present invention and having a light diffusing layer having a rectangular glass bead region and a spherical glass bead region separately.

Claims (12)

In the manufacturing method of the light-diffusion sheet provided with a reflection layer and a light-diffusion layer, The light diffusion layer is a method of manufacturing a light diffusion sheet, characterized in that the light diffusion layer forming ink containing a binder resin and a rectangular glass bead on the reflective layer by applying a screen printing method. The method of claim 1, The light diffusion layer forming ink further comprises a spherical glass bead, the manufacturing method of the light diffusion sheet. In the manufacturing method of the light-diffusion sheet provided with a reflection layer, a lower light-diffusion layer, and a light guide layer, The lower light diffusing layer is formed by applying a screen printing method to the lower light diffusing layer forming ink including a binder resin and a rectangular glass bead on the light guide layer. The method of claim 3, The ink for forming the lower light diffusion layer further comprises a spherical glass bead. The method of claim 3, Forming a light diffusion layer on the light guide layer further comprising the manufacturing method of the light diffusion sheet. The method of claim 5, The upper light diffusing layer is a method of manufacturing a light diffusing sheet, characterized in that formed by applying a screen printing method to the ink for forming the upper light diffusing layer comprising a binder resin and a rectangular glass bead. The method of claim 6, When the light source is located below the light diffusing layer, the upper light diffusing layer is formed by applying a screen printing method to form a dot pattern with an upper light diffusing layer forming ink including a rectangular glass bead only in a portion corresponding to the position of the light source. The manufacturing method of the light-diffusion sheet characterized by the above-mentioned. The method of claim 5, And the upper light diffusing layer is formed by applying the upper light diffusing layer forming ink by screen printing in a pattern in which a plurality of convex lens shapes are distributed on a plane. The method of claim 8, The upper light diffusing layer forming ink of different colors is applied by screen printing method separately for each color, so that the upper light diffusing layer is formed of a plurality of convex lens pattern regions having different colors. Manufacturing method. The method of claim 8, The convex lens pattern is a method of manufacturing a light diffusion sheet, characterized in that formed in multiple layers. The method according to claim 3 or 5, And a side light diffusion layer including a binder resin and a rectangular glass bead on a side not facing the light source of the light diffusion sheet, and a reflection layer outside the side light diffusion layer. The method of claim 5, The upper light diffusion layer is formed by screen printing a boundary portion of a region requiring high brightness with ink containing a binder resin and spherical glass beads, and screen printing a high brightness region inside the boundary portion with ink including a binder resin and a rectangular glass bead. Method for producing a light diffusion sheet, characterized in that.

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