KR101211715B1 - Backlight unit and Fabricating method of the same - Google Patents

Abstract

The present invention relates to a manufacturing process and structure of a backlight unit, and in particular, a step of forming a light guide module having a concave pattern corresponding to an LED or a reflective pattern by injecting and curing a resin into a master mold, and the light guide module to the LED. Alternatively, the backlight unit may be manufactured by manufacturing a backlight unit including a two-step mounting method on a PCB including a reflective pattern, wherein an air gap is formed between the external surface of the LED light source and the light guide module.
According to the present invention, the light guide module formed by using a mold or mechanical processing is manufactured by mounting and assembling on a printed circuit board equipped with an LED or a reflective pattern, thereby improving productivity and simplifying the process. It works.

Description

Backlight unit and its manufacturing method {Backlight unit and Fabricating method of the same}

The present invention relates to a manufacturing process that can increase productivity and manufacturing efficiency in manufacturing a light guide module, and a backlight unit manufactured thereby.

A liquid crystal display (LCD) is a display device that can control a desired image by individually supplying data signals according to image information to pixels arranged in a matrix form and adjusting light transmittance of the pixels. Since it does not emit light, it is designed to display an image by installing a back-light unit on its back side.

Referring to FIG. 1A, in the backlight device 1, a flat light guide plate 30 is disposed on a substrate 20, and a plurality of side type LEDs 10 (only one) are disposed on the side of the light guide plate 30. Is placed.

The light L incident from the LED 10 to the light guide plate 30 is reflected upward by a minute reflection pattern or a reflective sheet 40 provided on the bottom surface of the light guide plate 30, and exits from the light guide plate 30. 30) the backlight is provided to the upper LCD panel 50. In the backlight unit, as shown in FIG. 1B, a plurality of optical devices, such as a diffusion sheet 31, a prism sheet 32 and 33, a protective sheet 34, and the like are disposed between the light guide plate 30 and the LCD panel 50. It can be formed into a structure for further adding a sheet.

The backlight unit serves to evenly illuminate the display image on the back of the LCD which does not emit light itself, and the light guide plate is a component that performs brightness and uniform illumination of the backlight unit. It is one of the plastic molded lenses that uniformly transmits the emitted light to the entire LCD surface. Therefore, such a light guide plate is basically used as an essential component of such a backlight unit, but because of this, the thickness of the entire product can be reduced due to the thickness of the light guide plate itself. Is causing.

The present invention improves productivity by manufacturing a backlight unit by mounting a light guide module formed by using a metal mold or a mechanical process on a printed circuit board equipped with an LED or a reflective pattern, thereby improving the manufacturing process. To provide.

In addition, by removing the necessary light guide plate in the conventional backlight unit, and forming a structure to guide the light source using a film-type resin layer, the number of light sources can be reduced, the overall thickness is reduced, and the degree of freedom in product design It is another object of the present invention to provide a structure of a backlight unit that can be increased.

According to the present invention, there is provided a method for solving the above-mentioned problems, comprising the steps of: (1) forming a light guide module having a concave pattern corresponding to an LED or a reflective pattern by injecting and curing a resin into a master mold; And mounting the light guide module on the PCB including the LED or the reflective pattern.

In addition, the first step may be configured to form a light guide module that is cured by adding a UV curable or thermosetting resin. In this case, the resin added may be a material containing a urethane acrylate oligomer as a main raw material.

In addition, the resin described above may be implemented to further include a bead (bead) to increase the reflection of light to 0.01 ~ 0.3% compared to the total injected resin.

The structure of the backlight unit according to the present invention manufactured by the above-described manufacturing process is as follows.

Specifically, a plurality of LED light source formed on the printed circuit board; And a light guide module configured to diffuse and guide the emitted light toward the front. An air gap may be formed between an external surface of the LED light source and the light guide module.

In this case, the light guiding module may have a concave pattern corresponding to the LED at the bottom so that the LED is coupled to the concave pattern to implement the air gap, and the light guiding module may be implemented as a resin layer or a light guide plate. Can be.

In addition, the light guiding module described above may be implemented as a resin layer, and the resin layer may further include beads (beads) that increase reflection of light, in an amount of 0.01 to 0.3% of the total resin.

In this case, the resin layer may be formed of a material including a urethane acrylate oligomer as a main raw material.

In the structure of the backlight unit according to the present invention, the reflective pattern may be provided on the reflective film stacked on the printed circuit board, and an air gap may be formed between the outer surface of the reflective pattern and the concave pattern into which the reflective pattern is inserted. .

In addition, the reflective pattern may be formed by applying a reflective ink including any one of TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , Silicon, and PS.

In addition, the backlight unit according to the present invention may be formed on the upper surface of the resin layer, and may further include a diffuser plate printed with an optical pattern for blocking or reflecting the emitted light.

In this case, the optical pattern may be formed of a material including any one or more materials selected from TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , Silicon, and PS.

The backlight unit may further include a prism sheet or a protective sheet stacked on the diffusion plate.

According to the present invention, the light guide module formed by using a mold or mechanical processing is manufactured by mounting and assembling on a printed circuit board equipped with an LED or a reflective pattern, thereby improving productivity and simplifying the process. It works.

In particular, when the light guiding module is formed using a resin layer, it is assembled on a male printed circuit board which is prefabricated and hardened in a mask mold, thereby eliminating warpage or resin thickness variation that occurs when the resin is cured on a printed circuit board. In addition, it is possible to replace the defects occurring after curing of the resin can be reassembled to have an effect that can increase the manufacturing process.

In addition, the number of light sources can be reduced, the overall thickness of the backlight unit can be reduced, and the product design can be reduced by removing a light guide plate essential to the structure of a general backlight unit and forming a structure that induces a light source using a film type resin layer. It is effective to increase the degree of freedom.

In particular, by mounting the side-type light emitting diode in a direct type, it is possible to secure the optical characteristics while significantly reducing the number of light sources. And it is provided with a diffusion plate has the effect of increasing the stable light emission characteristics, optical properties of the light uniformity.

1A and 1B are conceptual views illustrating a structure of a backlight unit according to the prior art.
2A and 2B show a flowchart and a process conceptual diagram of a manufacturing process of the backlight unit according to the present invention.
3 is a conceptual view illustrating main parts of a backlight unit according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation according to the present invention. In the description with reference to the accompanying drawings, the same components are given the same reference numerals regardless of the reference numerals, and duplicate description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The present invention is to provide a technique for manufacturing a backlight unit by independently manufacturing and assembling a light guide module having a concave pattern corresponding to a pattern such as an LED or a reflective film provided on a printed circuit board.

2A and 2B illustrate a flowchart and a process diagram of a manufacturing process of a backlight unit according to the present invention. Referring to the drawings, a manufacturing process according to the present invention is largely a step 1 of processing a light guide module formed with a concave pattern corresponding to the LED or the reflective pattern and 2 to mount the light guide module on the PCB containing the LED or reflective pattern It may comprise a step.

Referring to the manufacturing process chart, the specific process sequence is as follows.

1. Manufacturing Step of Light Guide Module

First, as shown in step S1, to prepare a master mold provided with a predetermined pattern inside the frame (F). The master mold 1 is preferably provided with a pattern (2) corresponding to the LED or a pattern (3) corresponding to the reflective pattern on the printed circuit board according to the present invention.

Thereafter, as in step S 2, a process of injecting and curing a resin on the master mold 1 is performed. The resin to be injected is preferably made of a material that can perform a light guiding function to induce light emitted from the LED, which is a light source of the backlight unit, to the upper direction, which is basically a resin that can diffuse light. Of course, either can be used. In particular, as a preferred example of the present invention can be used a UV-curable resin having a high light transmittance or a resin of a thermosetting method, which can later increase the efficiency of the resin curing process in the master mold.

Furthermore, as the main material of the resin layer according to the embodiment of the present invention, a resin containing urethane acrylate oligomer as a main raw material may be used. For example, a mixture of urethane acrylate oligomer, which is a synthetic oligomer, with a polymer type of polyacrylic can be used. Of course, it may further comprise a monomer mixed with a low-boiling-point diluent type reactive monomer such as isobornyl acrylate (IBOA), hydroxypropyl acrylate (HPA), or 2-hydroxyethyl acrylate (HPA). A photoinitiator -hydroxycyclohexyl phenyl-ketone) or an antioxidant.

In addition, the resin layer may include beads to increase light diffusion and reflection. In this case, the bead preferably contains 0.01 to 0.3% of the total resin layer weight.

Thereafter, in step S 3, the resin is cured in the master mold and then separated to complete the light guide module 140.

As described above, the light guide module 140 may be embodied in a structure including concave patterns a and b corresponding to LEDs or reflection patterns protruding from the printed circuit board.

Of course, in the above-described process, the method of implementing the light guiding module by applying a liquid resin to the master mold and hardening was described. Alternatively, the light guide plate or the resin plate-type hardened structure may be provided by mechanical processing. It may be implemented to implement a light guide module.

2. Assembly step of light guide module and printed circuit board

Subsequently, in step S4, a process of mounting and assembling the light guide module 140 on a printed circuit board having the LED 130 or the reflective pattern 121 is performed. In this case, the concave patterns (a, b) in step S 3 corresponding to the LED 130 or the reflective pattern 121 are respectively inserted and coupled, and the LED 130 or the reflective pattern 121 and the concave pattern ( Inevitably, a and b are formed in a structure in which a constant gap (hereinafter, referred to as an air gap) is formed. That is, a method of assembling a cured independent structure. As a result, an air gap, which is a structure different from that of applying and curing a resin liquid on a direct printed circuit board, occurs.

Such a manufacturing method occurs in a manufacturing process of directly applying and curing a resin solution on a printed circuit board on which the LED 130 or the reflective pattern 121 is implemented, causing the printed circuit board to bend while the resin solution is cured. When the resin solution is cured, it is difficult to maintain the flatness of the entire light guide module. In addition, once the resin solution is cured, it is difficult to separate from the printed circuit board, thereby causing a problem that cannot be replaced.

However, when manufacturing and assembling the light guide module separately as in the manufacturing process according to the present invention, it is possible to eliminate the warpage phenomenon of the printed circuit board or the thickness variation during curing of the resin solution, and to replace the defects occurring after curing of the resin It can be reassembled to make the manufacturing process efficient.

3. Manufacturing of Backlight Unit

3 is a conceptual view illustrating main parts of a backlight unit according to the present invention.

In the structure manufactured by the above-described manufacturing step, as illustrated, the light guide module 140 having the concave pattern (or the first concave pattern) corresponding to the LED is laminated on the lower surface and induces the emitted light to the front. It is provided with a structure. In particular, in this case, the LED is coupled to the structure inserted into the first recess pattern, and the LED is coupled to the structure inserted into the first recess pattern, the outer surface of the LED light source and the first The air gap is formed between the inner surfaces of the concave pattern. In addition, when there is a reflective film having a reflective pattern on the printed circuit board, a concave pattern (or a second concave pattern) corresponding to the reflective pattern is provided so that the reflective pattern is inserted into the second concave pattern. Combined with each other, an air gap may exist between the outer surface of the reflective pattern and the inner surface of the second concave pattern surrounding the reflective pattern.

That is, this may be a feature implemented by the uniqueness of the manufacturing process according to the present invention, after manufacturing the light guide module independently, then assembled to form a printed circuit board.

In addition, a diffusion plate 160 may be disposed on the light guide module 140, and a prism sheet, a protective sheet, or the like may be additionally provided on the diffusion plate. In particular, an optical pattern 150 for blocking or reflecting light may be disposed between the diffusion plate 160 and the light guide module 140 according to the present invention. In this case, the optical pattern 150 may be integrally formed on the upper surface or the lower surface of the diffuser plate, or may be separated from the optical pattern integrally printed on the transparent substrate disposed between the upper part of the light guide module and the diffuser plate. It may be formed of a phosphorus structure.

In particular, the light guiding module 140 removes the existing light guiding plate and replaces it with a film-type resin so as to perform a function of guiding light forward.

The LED light source 130 is arranged on the printed circuit board 110 by at least one or more numbers to emit light, in a preferred embodiment of the present invention can use a side view LED (side view LED). That is, the direction of the light emitted from the LED light source 130 may not use the light source having a structure that is directed toward the side rather than going straight upward. In addition, the layout method is arranged in a direct type by using a side type light emitting diode, and by utilizing a resin layer that implements light diffusion and reflection functions, the total thickness of the backlight unit can be innovatively reduced while reducing the total number of light sources. Will be. In the illustrated figure, the lower portion of the printed circuit board 110 may be implemented in a structure in which the back cover B is bonded with an adhesive material P.

The light guide module 140 is stacked in a structure surrounding the LED light source 111 to perform a function of dispersing light of the light source emitted laterally. That is, the light guide module 140 may perform a function of the conventional light guide plate. As long as the resin layer is basically a resin of a material capable of diffusing light, any of the resin layers may be used in the manufacturing process.

In addition, the light guide module 140 may include a bead 141 to increase the diffusion and reflection of light. The bead 141 preferably includes 0.01 to 0.3% of the total resin layer weight. That is, the light emitted from the LED in the lateral direction is diffused and reflected through the light guide module 140 and the bead 141 to proceed upward, and the reflective film 120 and the reflective pattern 121 to be described later When provided, this reflection function can be further promoted. The presence of the light guiding module formed of the resin innovatively reduces the thickness occupied by the conventional light guiding plate to realize the thinning of the entire product, as well as having a soft material, which can be applied to a flexible display. It can be provided.

In addition, the reflective film 120 has a reflective material so as to disperse the light emitted from the light source, and at the same time, the reflective pattern 121 is provided through white printing to promote the dispersion of the light. Do. The reflective pattern may be printed using a reflective ink including any one of TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , Silicon, and PS.

The diffusion plate 160 serves to diffuse light emitted through the resin layer 140, and more preferably, includes an optical pattern 150 under the diffusion plate. The optical pattern 150 is preferably formed as a light shielding pattern so that a part of the light shielding effect can be implemented in order to prevent the optical properties deteriorate or yellowish light phenomenon due to the strong intensity of the light. That is, the light shielding pattern may be printed using the light shielding ink so that light does not concentrate. The optical pattern may not be a function of completely blocking light, but may be implemented to control light blocking degree or diffusing degree of light with one optical pattern to perform a function of partially blocking and diffusing light. Furthermore, more preferably, the optical pattern according to the present invention may be implemented as a superimposed printed structure of a complex pattern. The superimposed printing structure refers to a structure that forms one pattern and prints another pattern shape on the upper portion thereof.

For example, in implementing the optical pattern 150, a light shielding ink including at least one selected from TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , Silicon on the lower surface of the polymer film in the light emitting direction It can be implemented as a superimposed printing structure of the light shielding pattern using a diffusion pattern formed by using a, and a light shielding ink containing Al or a mixture of Al and TiO ₂ . That is, after the diffusion pattern is formed on the surface of the polymer film by white printing, the light shielding pattern may be formed thereon, or in the reverse order, the double structure may be formed. Of course, it will be apparent that the patterned design of the pattern may be variously modified in consideration of light efficiency, intensity, and light blocking rate. Alternatively, it is also possible to form a light-shielding pattern, which is a metal pattern, in the middle layer in a sequential layer structure, and a triple-layer structure in which diffusion patterns are formed in the upper and lower portions, respectively. In such a triple structure, it is possible to select and implement the above-described materials. As a preferred example, one of the diffusion patterns is implemented using TiO ₂ having excellent refractive index, and CaCO ₃ having excellent light stability and color sense is used together with TiO _2. It is possible to realize different diffusion patterns, and to secure light efficiency and uniformity through the triple structure of the structure implementing the light shielding pattern using Al having excellent concealment. In particular, CaCO ₃ functions to subtract the exposure of yellow light to finally implement white light, thereby realizing more stable light. In addition to CaCO ₃ , particles such as BaSO ₄ , Al ₂ O ₃ , and silicon beads Larger, similarly structured inorganic materials may be used. In addition, it is preferable that the optical pattern is formed by adjusting the pattern density so that the pattern density becomes lower as the distance from the emitting direction of the LED light source decreases.

In addition, the reflective film 120 according to the present invention is stacked on the printed circuit board, the LED light source 130 is projected to the outside through the hole formed on the reflective film. When the LED light source is implemented in a side-emitting type structure, the number of light sources can be greatly reduced as described above, and the reflection pattern 130 is implemented to greatly improve the reflectance of light in order to reduce the reduction rate. desirable.

The reflective pattern is preferably formed in the light output direction of the LED light source, and in particular, the pattern may be arranged so that the pattern density increases as the distance from the LED light source exits. In addition, the reflective pattern may be formed by printing using a reflective ink including any one or more materials selected from TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and Silicon.

In addition, the backlight unit according to the present invention can be applied to the LCD through the following configuration and operation. That is, the light is emitted from the LED 130, the emitted light is reflected and diffused in the light guide module 140 formed in place of the structure of the conventional light guide plate, which is particularly reflected on the reflective film 120 and the reflective pattern 121 As a result, the reflection efficiency is further increased, and light can be guided forward. The light passing through the resin layer 140 is subjected to a process of being diffused or shielded through the optical pattern 150, and thus the purified light has an optical property to be refined to increase uniformity, and a prism sheet to be added later. Through the optical sheet such as the 170 and the DBEF 180, white light is incident on the LCD panel.

As described above, the backlight unit according to the present invention removes the structure of the light guide plate, applies a side light-emitting LED as a light source, diffuses light through the resin layer, and induces light through reflection, thereby reducing the thickness and the number of light sources. On the other hand, by printing a hard coating resin layer on the upper surface of the resin layer to improve the protection of the resin layer and the bonding of each structure, and the problem of the luminance decrease and uniformity due to the reduction of the light source is provided with a reflection pattern and a light shielding pattern It can be adjusted to improve the optical properties.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

110: printed circuit board
120: reflective film
121: reflection pattern
130: Light source
140: light guide module
141: bead
150: optical pattern
160: diffusion plate
170: prism sheet
180: DBEF
G: air gap

Claims (14)

Preparing a printed circuit board including a reflective film having a reflective pattern formed thereon and a plurality of LED light sources mounted through the reflective film;
Resin is injected into the master mold and cured to form a light guide module having a first concave pattern corresponding to the LED light source and a second concave pattern corresponding to the reflective pattern,
Mounting the light guide module to the printed circuit board,
Mounting the light guide module on the printed circuit board,
Inserting the LED light source into the first recess pattern such that an air gap is formed between an outer surface of the LED light source and an inner surface of the first recess pattern;
And inserting the reflective pattern into the second recessed pattern such that an air gap is formed between the outer surface of the reflective pattern and the inner surface of the second recessed pattern.
The method according to claim 1,
The resin is,
A manufacturing method of a backlight unit which is an ultraviolet curing resin or a thermosetting resin.
Following claim 2,
The resin is a method of manufacturing a backlight unit is a material containing a urethane acrylate oligomer.
The method according to claim 2,
The resin is,
A method of manufacturing a backlight unit using a material further comprising a bead (bead) to increase the reflection of light relative to the total weight of the added resin.
Printed circuit board;
A reflective film formed on the printed circuit board and having a reflective pattern;
A plurality of LED light sources mounted on the printed circuit board through the reflective film;
And a light guide module having a first concave pattern corresponding to the LED light source and a second concave pattern corresponding to the reflection pattern on the lower surface of the light source, and inducing diffused light forward.
The LED light source is coupled to the structure inserted into the first recess pattern,
The reflection pattern is coupled to the structure inserted into the second recess pattern,
An air gap is formed between an outer surface of the LED light source and an inner surface of the first recess pattern;
And an air gap formed between an outer surface of the reflective pattern and an inner surface of the second recess pattern.
delete delete The method according to claim 5,
The resin layer further comprises a bead (bead) to increase the reflection of light in the resin layer further comprises 0.01 to 0.3% of the total weight of the resin.
The method according to claim 8,
The resin layer is a backlight unit made of a material containing a urethane acrylate oligomer.
delete The method according to claim 5,
The reflective pattern is a backlight unit formed by applying a reflective ink containing any one of TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , Silicon, PS.
The method according to claim 5,
The backlight unit,
And a diffuser plate formed on an upper surface of the resin layer and printed with an optical pattern for blocking or reflecting the emitted light.
The method of claim 12,
The optical pattern,
A backlight unit formed of a material containing at least one material selected from TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , Silicon, and PS.
The method of claim 12,
The backlight unit includes:
And a prism sheet or a protective sheet stacked on the diffusion plate.

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