KR101211709B1 - Back light unit within resin layer for light-guide and LCD using the same - Google Patents

Abstract

The present invention relates to a backlight unit, comprising a plurality of LED light sources formed on a printed circuit board and a resin layer stacked on the LED light sources to diffuse outgoing light to the front, the horizontal center of the LED light source At least one LED having a different light emission angle θ formed by the light exit surface with respect to the axis X is included.
According to the present invention, it is possible to improve the light efficiency by adjusting the light emitting angle of the LED, to reduce the overall thickness and at the same time to remove the hot spots, in particular to remove the light guide plate, which is essential for the structure of the general backlight unit, the resin of the film type By forming a structure to guide the light source using the layer, the number of light sources can be reduced, the overall thickness of the backlight unit can be reduced, and the degree of freedom in product design can be increased.

Description

Back light unit 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 improve the light efficiency by adjusting the light emitting angle of the LED, to reduce the overall thickness and at the same time can remove the hot spots, in particular the general backlight By removing the light guide plate essential to the structure of the unit and forming a structure that guides the light source using a film type resin layer, the number of light sources can be reduced, the overall thickness of the backlight unit can be reduced, and the degree of freedom of product design can be increased. To provide a structure that can be.

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 for inducing diffusion of light emitted from the LED light source forward, including, the optical axis (horizontal center axis) of the LED light source (X)) and the inclined angle of the printed circuit board.

In addition, it is possible to provide a backlight unit including at least one LED having a different light emission angle θ formed by the light exit surface with respect to the horizontal center axis X of the LED light source.

In addition, the light emission angle (θ) can be adjusted in the range of -45 degrees to +45 degrees, except that "+" is an angle formed counterclockwise with respect to the horizontal center axis (0 degrees), "-" Means an angle formed clockwise.

The LED light source in the present invention may use a side light emitting diode (side view).

In addition, the adjustment of the positive light emission angle of the LED light source may be implemented in a structure in which a region other than the light exit surface of the LED light source is buried in the printed circuit board, and the negative (−) of the LED light source. Control of the luminous angle may be implemented in a structure in which the LED light source is rotated at a predetermined angle (θ) with respect to the center of the printed circuit board.

In addition, the backlight unit in the above-described structure, the optical pattern layer disposed on the resin layer and including an optical pattern; And a diffuser plate disposed on the optical pattern layer.

In addition, the optical pattern layer may include a first substrate and a second substrate including the optical pattern therein; And a first air region surrounding a peripheral portion of the optical pattern.

In addition, an air gap module having a second air region may be further provided between the optical pattern layer and the diffusion plate.

The backlight unit according to the present invention may further include a reflective film having a reflective pattern stacked on an upper surface of the printed circuit board.

In this case, 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 Poly Stylen (PS).

The resin layer according to the present invention may further comprise a bead (bead) to increase the reflection of light compared to the total resin layer 0.01 to 0.3%.

In addition, the optical pattern,

The light blocking 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 (Poly Stylen).

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

Of course, the liquid crystal display device may be implemented using the backlight unit according to the present invention.

According to the present invention, it is possible to improve the light efficiency by adjusting the light emitting angle of the LED, to reduce the overall thickness and at the same time to remove the hot spots, in particular to remove the light guide plate, which is essential for the structure of the general backlight unit, the resin of the film type By forming a structure to guide the light source using the layer, the number of light sources can be reduced, the overall thickness of the backlight unit can be reduced, and the degree of freedom in product design can be increased.

In addition, when implementing to have a negative (-) light emission angle can be removed the center hot spot (hot spot) area, and when implemented to have a positive (+) light emission angle to capture the brightness of the center point in the shading pattern It is possible to increase the light efficiency, and also can be implemented to the advantage that the thickness can be adjusted slim according to the angle of the LED package for adjusting the light emitting angle of the LED.

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 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 it is also provided with a diffuser plate including an air layer has the effect of ensuring a stable light emission characteristics.

In addition, the optical pattern layer having the light shielding pattern layer and the air region surrounding the air gap module or the air gap module having the air layer can be provided, thereby increasing the optical characteristics of the backlight unit and the light uniformity. have.

1A and 1B are conceptual views illustrating a structure of a backlight unit according to the prior art.
FIG. 2A conceptually illustrates a cross-sectional view of a backlight unit according to the present invention, and FIGS. 2B and 2C illustrate examples of adjusting an emission angle of an LED light source in the structure of FIG. 2A.
Figure 3 shows the illuminance distribution for each angle according to the distance of the LED front portion when adjusting the emission angle of the present invention.
Figure 4 shows the distribution of Illumition for each emission angle in accordance with 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.

SUMMARY OF THE INVENTION The present invention includes a resin layer that removes and replaces a light guide plate in the structure of a conventional backlight unit, and improves light efficiency by adjusting the light emitting angle of an LED light source, and provides a structure capable of reducing the overall thickness. Shall be.

FIG. 2A conceptually illustrates a cross-sectional view of a backlight unit according to the present invention, and FIGS. 2B and 2C illustrate examples of adjusting an emission angle of an LED light source in the structure of FIG. 2A.

Referring to the drawings, the backlight unit according to the present invention includes a plurality of LED light sources 130 formed on the printed circuit board 110 and light formed on the printed circuit board 110 and emitted from the LED light sources. It includes a resin layer 140 to induce the diffusion to the front, it may be formed so that the optical axis (horizontal center axis (X)) and the printed circuit board of the LED light source to form an inclination angle.

In particular, in this case, at least one LED having a different light emission angle θ formed by the light exit surface with respect to the horizontal center axis X of the LED light source is included. Means the optical axis of the light exit surface of the LED light source.)

In this case, a reflective film 120 may be stacked on an upper surface of the printed circuit board, and a second gap may be formed between the diffusion plate 170 formed on the resin layer 140 and the optical pattern layer 150. An air gap module having an air region 160 may be further provided. In addition, a prism sheet, a protective sheet, and the like may be additionally provided on the diffusion plate.

In particular, the adjustment of the emission angle of the LED light source 130 according to the present invention when referring to Figure 2b and 2c, when considering the horizontal center axis (X) in the light emission direction from the center point of the LED light source 130 When the light emission angle of the horizontal center axis is defined as 0 degree, the light emission angle θ formed by the light exit surface with respect to the horizontal center axis X is adjusted in the counterclockwise direction. When the adjustment in the clockwise direction is referred to as adjustment in the negative (−) direction, the light emission angle θ is preferably adjusted to be adjusted between −45 degrees and +45 degrees.

Specifically, Figure 3 illustrates the illumination intensity distribution for each angle according to the distance of the LED front portion when adjusting the light emission angle of the present invention. Referring to the illuminance distribution shown, when considering the light emission angle, if the structure shown in Figure 2a is 0 degree of light emission angle, the hot spot is strongly when the light emission angle is positive (+) approaching 90 degrees Therefore, when hot spots are counted, if the light emission angle is laid down, illuminance decreases, but the hot spots are reduced. Negative adjustments also reduce hot spots and reduce illumination. Therefore, it is advantageous to have a negative light emitting angle and a light light emitting angle in terms of light efficiency for hot-spot removal in terms of uniformity. However, if the luminescence angle is more than +45 degrees, the hot spot is too hard to make uniformity, and if the luminescence angle is less than -45 degrees, the overall illuminance decreases due to the loss of light. The adjustment of the angle is preferably such that it can be adjusted between -45 degrees to +45 degrees.

Figure 4 shows the illumination distribution according to the emission angle, in the case of using a LED package having a negative emission angle to remove the hot spot, the central hot spot area is smaller control is advantageous, and positive light emission to increase the light efficiency It is preferable to implement to obtain the luminance of the center point in the light shielding pattern using the LED package having an angle. The luminance control region satisfying these two factors is -45 degrees to +45 degrees.

In addition, as shown in FIGS. 2B and 2C, the positive light emission angle of the LED light source 130 is adjusted so that an area other than the light exit surface of the LED light source 130 is located inside the printed circuit board. Since the structure is embedded in the bar, it is possible to take the thickness of the overall backlight unit slim (Slim). Of course, the adjustment of the negative (-) light emitting angle of the LED light source may be implemented in a structure in which the LED light source is rotated at a predetermined angle (θ) with respect to the center on the printed circuit board. In either case, it is preferable that the light exit surface is not embedded.

Hereinafter, the structure and operation of the backlight unit according to the present invention in which the adjustment of the emission angle of the above-described structure is implemented will be described in detail with reference to the configuration of FIGS. 2A and 2B.

As shown in FIG. 2, the LED light source 130 is arranged on the printed circuit board 110 in at least one number and emits light. In a preferred embodiment of the present invention, a side view LED is shown. Can be used. In particular, the light emission angle θ of the LED light source in the present invention is preferably to be adjusted between -45 degrees to +45 degrees.

In this way, the light emitted from the LED light source 130 may not use the light source having a structure that emits toward the side rather than going straight upward. In addition, the arrangement method is arranged in a direct type using a side type light emitting diode, and while reducing the total number of light sources by using the resin layer 140 and the diffusion plate 170 to implement light diffusion and reflection functions. By adjusting the light emission angle, the hot spots can be eliminated and the light uniformity can be improved, and the overall thickness of the backlight unit can be reduced.

In addition, the resin layer 140 is stacked in a structure surrounding the LED light source 130, and serves to disperse the 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. For example, the main material of the resin layer according to one embodiment of the present invention may be a resin having urethane acrylate oligomer as a main material. 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.

The resin layer 140 may include beads 141 to increase diffusion and reflection of light. Preferably, the bead comprises 0.01 to 0.3% by weight of the total resin layer. That is, the light emitted laterally from the LED is diffused and reflected through the resin layer 140 and the bead 141 to proceed upwards, 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 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 particular, the optical pattern layer 150 formed on the resin layer 140 includes a first substrate 150A and a second substrate 150B including the light blocking pattern 151 therein. And an adhesive layer applied to a portion other than the first air region 152 surrounding the peripheral portion of the optical pattern 151. As the first substrate 150A and the second substrate 150B, a substrate made of a material having excellent light transmittance may be used. For example, PET may be used. The optical pattern 151 disposed between the first substrate 150A and the second substrate 150B basically serves to prevent the light emitted from the LED light source from being concentrated, and the first substrate 150A. Alternatively, the second substrate 150B may be implemented through light shielding printing, and the two layers may be bonded to each other by an adhesive layer for applying an adhesive material in a structure surrounding the periphery of the light shielding pattern. In other words, the adhesive structure of the first substrate 150A and the second substrate 150B can also function to fix the printed light-shielding pattern 151. The adhesive layer may be a thermosetting PSA, a thermosetting adhesive, or a UV cured PSA type material.

Specifically, the optical pattern 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 phenomenon that the light is excessively strong, so that the optical characteristics deteriorate or yellowish light is emitted. 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 151, a light shielding ink containing at least one material selected from the group consisting of TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and Silicon on the lower surface of the polymer film in the light- And a light-shielding pattern using a light-shielding ink containing a mixed material of Al or Al and TiO ₂ . That is, after the diffusion pattern is formed by white printing on the surface of the polymer film, a light shielding pattern may be formed thereon, or a double structure may be formed 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, in the sequential layer structure, a light shielding pattern, which is a metal pattern, may be formed on the center layer, and a triple structure may be formed on the upper and lower portions thereof to implement a diffusion pattern, 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 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.

The reflective film 120 may have a reflective material so as to disperse the light emitted from the light source, and at the same time, the reflective pattern 121 may be provided through white printing to promote dispersion of light. In particular, the reflective film 120 is laminated on the printed circuit board, the LED light source 130 is protruded to the outside through the hole formed on the reflective film. When the LED light source is implemented as a side emitting type structure, the number of light sources can be greatly reduced as described above, and the reflection pattern 130 is provided to greatly improve the reflectance of light in order to reduce the reduction rate. Will. 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 Poly Stylen (PS). 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 the backlight unit according to the present invention, a structure including an air layer (second air region) 160 between the optical pattern layer 150 and the diffusion plate 170 may be added, and the second air region 160 may be added. Due to the presence of), the effect of diffusing the light emitted from the light source and improving the uniformity of the light is realized. In addition, in order to minimize the deviation of the light transmitted through the resin layer 140 and the optical pattern layer 150, the thickness of the second air region 160 is preferably formed to be 0.01 ~ 2mm. The second air region 160 may be formed by implementing a structure capable of forming an air layer under the diffusion plate, and defined as an “air gap module” including a second air region implemented through such a structure. do. The air gap module includes both a method of forming an air region (air layer) by processing the diffusion plate itself or a structure of forming an air region by forming a separate structure below the diffusion plate.

The backlight unit according to the present invention described above may be applied to the LCD through the following configuration and operation. Referring to FIG. 2A, light is emitted from the side emitting type LED 130 in the lateral direction, and in particular, the light emitting angle of the light output is controlled to be adjusted in the range of -45 to +45 degrees. As described above, due to the adjustment of the light emission angle, the occurrence of hot spots can be primarily eliminated, and further, the light uniformity can be secured and the overall thickness can be reduced.

Furthermore, the emitted light is reflected and diffused from the resin layer 140 formed instead of the structure of the conventional light guide plate, and prevents the light from being concentrated through the optical pattern layer 150, and the second air region 160 formed under the diffuser plate. Through this, the deviation of light can be minimized.

In addition, the light emitted by the reflective film 120 and the reflective pattern 121 is higher the reflection efficiency, 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 optical pattern layer 150, and thus the purified light is formed in the lower portion of the diffuser plate. Once again through the optical properties can be purified uniformity can be increased. In addition, a white light is incident on the LCD panel via an optical sheet such as a prism sheet or 190 which is added later.

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, it is possible to control the problem of the decrease in brightness and uniformity due to the reduction of the light source with the reflection pattern, the light shielding pattern, and the air region of the air gap module. It will be possible to improve.

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: Resin layer
150: optical pattern layer
151: optical pattern
152: first air zone
160: second air area
170: diffusion plate

Claims (15)

A plurality of LED light sources formed on the printed circuit board;
And a resin layer in close contact with the LED light source, and having a structure for embedding the LED light source to inject light emitted and stacked forward on the printed circuit board to the front.
And a horizontal center axis (X), which is an optical axis of the light exit surface of the LED light source, forms an inclination angle with the printed circuit board.
The method according to claim 1,
And at least one LED having a different light emission angle θ formed by the light exit surface with respect to the horizontal center axis (X) of the LED light source.
The method according to claim 2,
The emission angle (θ) is a backlight unit that is adjusted in the range of -45 degrees to +45 degrees.
(However, "+" means the angle made counterclockwise with respect to the horizontal center axis (0 degree), and "-" means the angle made clockwise.)
The method according to claim 3,
The LED light source is a backlight unit is formed using a side light emitting diode (side view).
The method of claim 4,
Adjusting the light emission angle of the positive (+) of the LED light source,
And a region other than the light exit surface of the LED light source is embedded in the printed circuit board.
The method of claim 4,
Adjusting the negative light emission angle of the LED light source,
The backlight unit is implemented in a structure in which the LED light source is rotated by a predetermined angle (θ) relative to the center on the printed circuit board.
7. The method according to any one of claims 1 to 6,
The backlight unit includes:
An optical pattern layer disposed on the resin layer and including an optical pattern;
And a diffuser plate disposed on the optical pattern layer.
The method of claim 7,
The optical pattern layer,
A first substrate and a second substrate including the optical pattern therein;
And a first air region surrounding a peripheral portion of the optical pattern.
The method of claim 7,
And an air gap module having a second air region between the optical pattern layer and the diffusion plate.
The method of claim 7,
The backlight unit includes:
And a reflective film having a reflective pattern stacked on an upper surface of the printed circuit board.
The method of claim 10,
The reflective pattern is formed by applying a reflective ink containing any one of TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , Silicon, PS (Poly Stylen).
The method of claim 7,
The resin layer,
It further includes a bead that increases the reflection of light,
The bead is a backlight unit 0.01 to 0.3% of the weight of the total resin layer is included on the resin layer.
The method of claim 7,
The optical pattern is
TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O _{3 It} is formed as a diffusion pattern formed using a light shielding ink containing any one or more materials selected from silicon or two or more mixtures,
A backlight unit embodied by a superimposed printing structure of a light shielding pattern formed of a light shielding ink including the diffusion pattern and Al or Al mixed with TiO ₂ .
The method of claim 12,
The backlight unit includes:
And a prism sheet or a protective sheet stacked on the diffusion plate.
Liquid crystal display comprising the backlight unit of any one of claims 1 to 6.

Images