KR20110104400A - Back light umit within resin layer for light-guide and lcd using the same - Google Patents

Abstract

The present invention relates to a backlight unit, and in particular, comprising a plurality of LED light sources formed on a printed circuit board and a resin layer stacked on the LED light source to induce the emitted light forward, wherein the resin layer is an oligomer And a synthetic resin comprising a mixture of a polymer resin and a polymer resin.
According to the present invention, the light guide plate is removed to realize thinning of the entire product, and the resin layer is formed by using a mixture composition of oligomer type and polymer type, thereby increasing the productivity and reliability of the oligomer type and polymer type. By having the advantages of improving the adhesive properties of the furnace, there is also an effect that can implement a higher quality product.

Description

Back light unit and liquid crystal display using the same {Back light umit within resin layer for light-guide and LCD using the same}

The present invention relates to a backlight unit capable of thinning the structure of a backlight unit by removing the structure of the light guide plate and securing a light efficiency and a liquid crystal display device using the same.

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 has been made to solve the above problems, an object of the present invention is to remove the light guide plate essential to the structure of a general backlight unit, and to form a structure for inducing a light source using a resin layer containing oligomer as a main component, Provides a backlight unit that can reduce the number of light sources, reduce the overall thickness of the backlight unit, secures tensile strength, constant temperature and humidity, and heat resistance, and increases the degree of freedom in design and the liquid crystal display device using the same. There is.

In order to solve the above problems, the present invention includes a plurality of LED light source formed on a printed circuit board; and a resin layer stacked on the LED light source, to diffuse the light emitted forward; The layer is to provide a backlight unit comprising a synthetic resin comprising a mixture of oligomer and polymer resin (polymer type).

In particular, the above-described composition may be formed to include 20 to 42% of the mixture of the oligomer and polymer resin, 30 to 63% of the monomer, and 1.5 to 6% of the additive.

Specifically, the oligomer and the polymer resin may be formed of a mixture of 10% to 21% urethane acrylate oligomer and 10% to 21% polyacryl. The monomer is 10% to 21% IBOA (isobornyl acrylate) and HPA ( Hydroxypropyl Acrylate) 10 ~ 21%, 2-HEA (2-Hydroxyethyl Acrylate) can be formed with a mixture of 10 ~ 21%, the additive, 1-5% photoinitiator, 0.5-1% antioxidant can be formed Can be.

In another backlight unit having the above-described resin layer, the LED light source may be a side type light emitting diode (side view), and further include a reflective film having a reflective pattern formed on the printed circuit board. Can be.

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

In addition, the resin layer may be configured to further include a bead (bead) to increase the reflection of light relative to the total resin layer weight 0.01 ~ 0.3%.

In particular, the optical pattern formed on the diffusion plate, the diffusion pattern is formed using a light shielding ink containing any one or more materials selected from TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , Silicon, and Al Alternatively, the light blocking pattern may be formed to have an overlapping structure of a light shielding pattern using a light shielding ink including a mixture of Al and TiO ₂ .

The reflective pattern may be formed by applying a reflective ink including any one of TiO ₂ and Al ₂ O ₃ .

It will be apparent that the liquid crystal display device may be implemented using the backlight unit according to the present invention. Specifically, a side view LED is used as a light source, and the resin layer according to the present invention, which is stacked in a structure for accommodating the light source, is used as a light guide plate, but is laminated on the printed circuit board. And a reflective film including a reflective film having a reflective pattern formed thereon, and a diffuser plate formed on an upper surface of the resin layer and having an optical pattern for blocking or reflecting the emitted light. Of course, it may further include a prism sheet or a protective sheet laminated on the diffusion plate.

According to the present invention, the number of light sources can be reduced by removing the light guide plate essential to the structure of a general backlight unit and forming a light source using a resin layer containing oligomer as a main component, thereby reducing the overall thickness of the backlight unit. It has the effect of providing a backlight unit and a liquid crystal display device using the same, which is thin and can increase the degree of freedom of design and design, which has a tensile strength, reliability of constant temperature and humidity, and heat resistance.

In particular, the composition of the resin layer is formed using a mixture composition of oligomer type and polymer type, so that it is possible to have the advantages of increasing the productivity and reliability of the oligomer type and improving the adhesive properties of the polymer type, thereby achieving higher quality. There is also an effect to implement the product.

In addition, by mounting the side-emitting light emitting diode in a direct type, it is possible to secure the optical characteristics while significantly reducing the number of light sources, and can be applied to the structure of the flexible display by removing the light guide plate, and a reflective film including a reflective pattern in the resin layer And a diffusion plate including a light shielding pattern, thereby ensuring stable light emitting characteristics.

1A and 1B are conceptual views illustrating a structure of a backlight unit according to the prior art.
2A is a conceptual view illustrating main parts of a backlight unit according to the present invention.
Figure 2b is a functional state diagram showing the functions of the resin layer and the beads of the backlight unit according to the present invention.
3 is a table showing an embodiment of the composition constituting the resin layer according to the present invention.
4A is an exemplary view showing an optical pattern according to the present invention.
4B is an exemplary view showing a reflection pattern according to the present invention.
5 is a view showing an operating state of the 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 removes the light guide plate from the structure of a conventional backlight unit, is formed of a resin layer containing the oligomer as a main component and a polymer type resin such as polyacryl, and innovatively reducing the overall thickness of the backlight unit, It is a main idea to provide a structure that can reduce the number of light sources.

2 is a conceptual diagram illustrating a main part of a backlight unit according to the present invention. 2,

The LED light source 111 is arranged on at least one or more numbers on the printed circuit board 110 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 111 does not go straight to the top, but may use a light source having a structure that exits toward the side. 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.

The resin layer 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 resin layer 140 may perform a function of the conventional light guide plate. It is needless to say that the resin layer can be basically made of any resin capable of diffusing light.

3 is a diagram showing a preferred embodiment of the composition for forming a resin layer according to the present invention in the above-described structure.

As the main material of the resin layer according to one embodiment of the present invention, a resin (oligomer type) 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.

More specifically, the resin layer may be made of a synthetic resin containing a mixture of oligomer and polymer resin (polymer type), in particular 20-42%, 30-63% monomer, mixture of oligomer and polymer resin (polymer type), The composition formed with the composition of the additive 1.5-6% can be used.

In this case, the oligomer and the polymer resin may be formed of a mixture of 10 to 21% of urethane acylate oligomer and 10 to 21% of polyacryl. In addition, the monomer is a low boiling diluent reactive monomole, which is formed of a mixture of 10 to 21% of IBOA (isobornyl acrylate), 10 to 21% of HPA (Hydroxypropyl Acrylate), and 10 to 21% of 2-HEA (2-Hydroxyethyl Acrylate) The additive may be added to 1 to 5% of the photoinitiator to perform a function of initiating photoreactivity, and may be formed of a mixture to improve yellowing by adding 0.5 to 1% of an antioxidant. have.

Formation of the resin layer using the above-described composition forms a resin layer such as UV resin instead of the light guide plate, so that the effect of the conventional light guide plate can be substituted, and the refractive index, thickness can be adjusted instead, and the composition described above To compensate for the shortcomings of the surface adhesive strength, which is a disadvantage of the oligomo type, and to solve the problem of lowering the mass production speed due to the long-term curing of the polymer type, it is possible to satisfy both the adhesive properties, the reliability and the mass production speed. Can be.

In particular, the formation of the resin layer according to the present invention is preferably made through the following special process.

That is, the resin layer according to the present invention uses a urethane acrylate oligomer as a main material, and is mixed with a polymer type of polyacryl and has a UV curing wavelength of 300 to 300 Main reaction at 350㎛, using a mercury lamp and a metal (gallium) lamp with a wavelength of 400㎛, by adding N ₂ when polymer type curing, balance balance with the general oligomer type (oligomer type) ), Flexible, excellent adhesion, and maintain the refractive index of the PMMA light guide plate to overcome the limitations of the light guide plate.

In particular, if nitrogen purging is not carried out when the polymer and oligomer are mixed, surface wrinkles and cracks may occur due to internal curing and surface hardening balance. Due to this, it is more preferable to be able to cure quickly even in general metal halides.

Hereinafter, as shown in FIG. 3, a resin layer formed only of a polymer (1type), a resin layer formed only of a single oligomer (2type), and a comparison of characteristics of the resin layer (3type) by mixing the oligomer and the polymer according to the present invention. The experimental results will be described.

1. Adhesion (tensile strength) reliability test

This test is to perform a test sheet to measure the tensile strength using a thin film tensile tester (Instron, USA), the coating thickness of the resin layer on the upper and lower grips of the equipment to 1300㎛, horizontal × vertical (50mm × 100mm) And the upper grips are raised, and the loads on the load cells are compared and observed in real time. (Test conditions are 0.1m per minute)

{Table 1}

Referring to the above test results, in general, the oligomer single type is low in the tensile strength plane, it can be seen that 3 type according to the present invention shows a tensile strength comparable to the polymer type of 1 type.

2. Constant temperature and humidity reliability test

In this test, a constant temperature and humidity chamber (THB (Temperature Humidity Bias), THB SH-641 / ESPEC Co., Ltd. (Japan)) was applied to a constant temperature and humidity in the chamber, and the constant temperature and humidity characteristics were compared. The test conditions were maintained at 60 ° C. and 95% humidity for 240 hours, and then the characteristics were compared (as shown in FIG. 2. It was made.)

The resin layer was formed on the above-mentioned reflective film with a coating thickness of 1300 µm and width x length (115 mm x 175 mm), respectively, and after applying the above test conditions, the appearance and lighting tests were compared.

{Table 2}

Referring to the table shown, 3type according to the invention and the resin layer of the oligomer-only 2type is blue light (Blue light) is formed, the degree of adhesion does not change, but the only type of the polymer layer of the resin layer only yellowing phenomenon front part Problem occurred, and the whitening phenomenon was derived. In addition, the adhesion characteristics were also bad.

3. Heat resistant reliability test

This test is to evaluate the heat resistance of the product by applying a certain heat in the oven {HT330 / ETAC (Japan)} for a certain time. Test conditions, after 240 hours at 80 ℃, the heat resistance and adhesion properties of the resin layer was compared. In the test method, a coating thickness of 1300 μm and a width × length (115 mm × 175 mm) were respectively formed on the reflective film in FIG.

{Table 3}

In this test, 3 type according to the present invention and 2 type, the resin layer of the oligomer only, blue light is formed, and the degree of adhesion is not changed, but 1 type, the resin layer of the polymer only, is a defect in which yellowing occurs on the front part. This occurred.

Comparing the above three characteristic tests, the resin layer having the composition of the oligomer and polymer blending type according to the present invention is more effective than the single resin layer in various aspects such as tensile strength, constant temperature and humidity characteristics, heat resistance, reliability, adhesion characteristics. You can check it.

 Referring to the structure of the present invention shown in Figures 2a and 2b, the operation of the configuration of the unique backlight unit according to the present invention in combination with the characteristics of the resin layer described above will be described in detail as follows.

In the backlight unit according to the present invention, the resin layer 140 may further include a bead 141 to increase light diffusion and reflection. The beads 141 preferably include 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 resin layer 140 and the beads so that the light can travel upward, and the reflective film 120 and the reflective pattern 121 to be described later are provided. As a result, the reflection function can be further promoted. The presence of the resin layer innovatively reduces the thickness occupied by the conventional light guide plate, thereby realizing thinning of the entire product, as well as having a soft material, and thus having a versatility applicable to a flexible display. do.

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 it is more preferably provided with a reflective pattern 121 through white printing to promote the dispersion of light. Do. The reflective pattern may be printed by using a reflective ink including any one of TiO ₂ and Al ₂ O ₃ .

In addition, the diffusion plate 150 serves to diffuse the light emitted through the resin layer 140, in particular, the light is excessively strong so that the optical characteristics deteriorate or yellowish light (yellowish) In order to prevent the optical pattern 151 is preferably formed so that a portion of the shading effect can be implemented. That is, the light shielding pattern may be printed using the light shielding ink so that light does not concentrate.

The optical pattern 151 may be implemented in a manner that is basically printed on the lower surface or the upper surface of the diffuser plate 150, particularly preferably at the position of the LED light source 111 disposed below the diffuser plate It is preferable to arrange | position in the direction in which light exits (pre-direction). That is, it may be disposed on the diffuser plate at a position corresponding to the vertical upper surface or the light exit direction surface of the LED light source.

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, referring to FIG. 4A, in implementing the optical pattern 151, at least one selected from TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and Silicon on a lower surface of the diffusion plate in the light emitting direction. The diffusion pattern 151a formed using the light shielding ink including a material and the light shielding pattern 151b using the light shielding ink containing Al or a mixture of Al and TiO ₂ may be implemented. In other words, after the diffusion pattern 151a is formed by white printing on the surface of the diffusion plate, the light shielding pattern 151b may be formed thereon or may be formed in a double structure in the reverse order. 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, the light blocking pattern 151b, which is a metal pattern, may be formed in the middle layer in the sequential layer structure, and may be formed in a triple structure that implements the diffusion pattern 151a on the upper and lower portions thereof. 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 in view of light efficiency that the optical pattern is formed by adjusting the pattern density so that the pattern density is lowered away from the emitting direction of the LED light source.

In addition, in the structure of the backlight unit according to the present invention, in particular, in the above-described structure, the present invention is the optical pattern between the resin layer 140 and the optical pattern 151 formed on the surface of the diffusion plate 150 A surface treatment layer (not shown) may be further provided to planarize pattern irregularities of the air gap, and the air layer may be formed due to a step generated when the optical pattern 151 of the diffusion plate is adhered to the resin layer 140 disposed below the diffuser plate. In order to exclude the difference between the dark portion and the bright portion generated by the formation, it is preferable to implement a flattened layer (layer) structure to cover the step of the entire optical pattern 151. In addition, the surface treatment layer is more preferably to improve the adhesion using the same material as the resin layer 140.

4B is a plan view showing the structure of a reflective film and a reflective pattern according to the present invention.

That is, the reflective film 120 according to the present invention is stacked on the printed circuit board, and the LED light source 111 protrudes to the outside through the holes 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 exit direction of the LED light source, as shown in the example, and may be arranged such that the pattern density becomes higher as the distance from the light exit direction of the LED light source increases. That is, by increasing the pattern density of the second region 132 far from the emission direction than the first region 131 close to the emission direction, the reflectance can be increased. Of course, the structure of the pattern can be implemented in various shapes according to the design intention. In addition, the reflective pattern may be formed by printing using a reflective ink including any one of TiO ₂ and Al ₂ O ₃ .

5 is an operating state diagram showing an operating state of the structure of the backlight unit according to the present invention described above.

As shown in the drawing, the backlight unit according to the present invention emits light laterally from the side-emitting LED 111, and the emitted light is reflected and diffused from the resin layer 140 formed instead of the structure of the conventional light guide plate. In particular, the reflection film 120 and the reflection pattern 130 by the reflection efficiency is further increased, it is possible to guide the light forward. The light passing through the resin layer 140 is subjected to a process of being diffused or shielded through the optical pattern 151 formed on the diffuser plate 150. White light enters the LCD panel through the sheet.

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, the luminance reduction and uniformity problems caused by the reduction of the light source can be compensated for by the optical patterns such as the reflection pattern, the light shielding pattern, and the diffusion pattern, thereby realizing the uniformity of the image quality.

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
111: LED light source
120: reflective film
130: reflection pattern
140: Resin layer
150: diffusion plate
151: optical pattern
151a: diffusion pattern
151b: shading pattern
160: prism sheet

Claims (12)

A plurality of LED light sources formed on the printed circuit board; and
Including a resin layer laminated on the LED light source, to induce the emitted light to the front diffusion;
The resin layer is a backlight unit, characterized in that made of a synthetic resin containing a mixture of oligomer and polymer resin (polymer type).
The method according to claim 1,
The resin layer,
A backlight unit comprising 20 to 42% of a mixture of an oligomer and a polymer resin, 30 to 63% of a monomer, and 1.5 to 6% of an additive.
The method according to claim 2,
The oligomer and polymer resin,
A backlight unit, which is a mixture of 10 to 21% of urethane acylate oligomer and 10 to 21% of polyacrylic acid.
The method according to claim 2,
The monomer,
A backlight unit comprising a mixture of 10 to 21% of IBOA (isobornyl acrylate), 10 to 21% of HPA (Hydroxypropyl Acrylate), and 10 to 21% of 2-HEA (2-Hydroxyethyl Acrylate).
The method according to claim 2,
The additive,
A backlight unit, characterized in that a mixture of 1-5% photoinitiator, 0.5-1% antioxidant.
The method according to any one of claims 1 to 5,
The LED light source is a side type light emitting diode (side view), the backlight unit, characterized in that further comprising a reflective film having a reflective pattern stacked on the upper surface on the printed circuit board.
The method of claim 6,
And a diffuser plate formed on an upper surface of the resin layer and printed with an optical pattern for shielding or reflecting the emitted light.
The method according to claim 7,
The resin layer further comprises a bead (bead) to increase the reflection of light, the backlight unit further comprises 0.01 to 0.3% of the total resin layer weight.
The method according to claim 7,
The optical pattern,
A diffusion pattern formed using a light shielding ink including at least one material selected from TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and Silicon,
A backlight unit comprising an overlapping structure of a light shielding pattern using a light shielding ink containing Al or a mixture of Al and TiO ₂ .
The method according to claim 7,
The reflective pattern is a backlight unit, characterized in that formed by applying a reflective ink containing any one of TiO ₂ , Al ₂ O ₃ .
Side view LED is used as a light source,
Using the resin layer of any one of claims 1 to 5 laminated in a structure for receiving the light source as a light guide plate,
A reflective film having a reflective pattern stacked on an upper surface of the printed circuit board;
And a diffuser plate formed on an upper surface of the resin layer and including a diffuser plate on which an optical pattern for blocking or reflecting emitted light is printed.
The method of claim 11,
And a prism sheet or a protective sheet stacked on the diffusion plate.

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