TWI493255B - Back light unit within resin layer for light-guide and lcd using the same - Google Patents

Description

a backlight unit in a range of a resin layer for guiding light and an LCD using the same

The invention relates to a backlight unit, which omits a light guide plate and has a diffusion plate; the diffusion sheet is formed with an optical microstructure thereon for improving light shielding efficiency and atomization effect. (haze effect).

Generally, a liquid crystal display (LCD) is a pixel that can separately provide a data signal according to image information to pixels arranged in a matrix array, and adjust optical transmittance of the pixels (optical transmittance) ) to form a desired image. Since the LCD itself does not emit light, a backlight unit is mounted on the rear surface of one of the LCDs to display an image.

Referring to FIG. 1, the backlight unit 1 is configured such that a planar light guide plate 30 is placed on a substrate 20, and a plurality of side view LEDs (side view LEDs) are drawn. One of them is disposed on one side of one of the light guide plates 30 of an array.

The light L transmitted from the side light-emitting diode 10 to the light guide plate 30 is reflected by a fine reflection pattern or a reflection plate 40 formed on one lower surface of the light guide plate 30, and is self-guided. The light panel 30 exits and then provides backlighting to an LCD panel 50 located above the light guide panel 30.

As shown in FIG. 2, the backlight unit may further include a plurality of optical sheets on the light guide plate 30. Between the LCD panel 50 and the LCD panel 50, there are: a diffusion sheet 31; slabs 32, 33 (prism sheets); and a protective sheet 34.

Such a backlight unit has a function of uniformly illuminating the LCD from the back of the LCD (the LCD is not self-illuminating) so that a display image can be seen. The light guide plate has a function of providing uniform illumination to the backlight unit, and is a plastic molded lens that can uniformly transmit light from a light source (such as a light emitting diode) to a full plane of the LCD. Therefore, such a light guide plate is basically an essential component of the backlight unit. However, the conventional backlight unit has a problem in that, due to the thickness of the light guide plate, it is difficult to achieve a thin and light requirement for the entire product, and when the backlight unit has a large area, the image quality may be degraded.

In addition, the light diffusing sheet or the diffusing sheet 31 for diffusing light in the conventional backlight unit has a light shielding microstructure to prevent light from being concentrated. This light-shielding microstructure uses silver (Ag) to perform a light-shielding effect. However, the optical microstructure using silver for obtaining a light-shielding effect has a drawback in that a portion thereof having the microstructure is completely shielded from light, so that it is difficult to achieve uniformity of light on an entire portion, and yellow light Due to the yellow light emitted by the self-luminous diode source, the reliability of the backlight unit that emits white light is reduced.

An aspect of the present invention provides a backlight unit that forms an optical microstructure to shield or diffuse light onto one surface of a light diffusing sheet of the backlight unit, and expands The scattered micro-structure is combined with a metal microstructure to achieve light uniformity and achieve a yellow light shielding effect, thereby obtaining a reliable light quality.

Another aspect of the present invention is to provide a backlight unit which can omit a light guide plate as a necessary component in a general backlight unit and form a light source guide using a film-type resin layer. The guiding structure, thereby reducing the number of light sources, thereby achieving the thinness of the overall backlight unit and enhancing the freedom of product design.

According to an embodiment of the invention, a backlight unit includes: a plurality of light emitting diode light sources formed on a printed circuit board (PCB), the printed circuit board is formed by stacking reflective films; a resin layer is stacked on the a printed circuit board for diffusing and guiding light forward; and a diffuser having an optical microstructure printed thereon for shielding light emitted from the light emitting diode sources. The backlight unit may further include: a surface treatment layer formed to accommodate the optical microstructure between the resin layer and the light diffusion sheet.

According to another embodiment of the present invention, the optical microstructure may be formed on one surface of the diffusion sheet, and may include a diffusion microstructure, implemented in at least one layer, or combined with the diffusion microstructure layer and one of the light shielding microstructures. .

The invention has the advantage of being effective in that an optical microstructure is formed in a backlight unit A surface of a diffusion sheet is used to shield or diffuse light, and a diffusion microstructure is combined with a metal microstructure to achieve light uniformity and to shield yellow light, thereby obtaining a reliable light quality.

In particular, the power efficiency of the present invention is that it can omit a light guide plate as a necessary component in a general backlight unit, and use a film type resin layer to form a light source guiding structure, thereby reducing the number of light sources, thereby achieving The overall backlight unit is thin and light and enhances the freedom of product design.

In addition, the one-side illumination type two-pole system is mounted as a direct type backlight module to significantly reduce the number of light sources and achieve optical properties, and a light guide plate is omitted, so that the The backlight unit can be applied to an elastic display structure, and a resin layer provides a reflective film having a reflective microstructure and a light diffusing sheet having a light-shielding microstructure to achieve stable light-emitting properties.

The above and other advantages and advantages of the present invention will be set forth in the accompanying drawings.

Best Mode

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals will be assigned to the same elements in the illustrated explanation, and the repeated explanation will be omitted. It should be understood that the terms "first," "second," and the like are used herein to describe various elements; these elements are not limited to such terms. These terms are used to distinguish the components By.

The present invention relates to a backlight unit which is formed with a diffusion sheet having an optical microstructure to effectively shield or diffuse light, thereby enhancing light efficiency, omitting a light guide plate as a necessary component in a general backlight unit, and A resin layer is formed at the position of the original light guide plate, thereby significantly reducing the overall thickness of the backlight unit and reducing the number of light sources. In particular, the present invention relates to a backlight unit having a surface treatment layer which can remove an air layer due to an optical microstructure step when a diffusion sheet and a resin layer are coupled to each other.

"Implementation"

3 and 4 illustrate an arrangement structure of a backlight unit according to the present invention. The backlight unit according to the present invention includes: a plurality of light emitting diode light sources 111 formed on a printed circuit board 110; and a resin layer 140 stacked on the light emitting diode light source 111 to diffuse and guide the light forward. Of course, in this case, a reflective film 120 is stacked on the upper surface of one of the printed circuit boards 110, a diffusion sheet 150 is provided over the resin layer 140, and a die 160 and a protective sheet 170 are attached. Also provided above the diffusion sheet 150.

In particular, in the above configuration, preferably, a surface treatment layer 152 is provided between the resin layer 140 and an optical microstructure 151 formed on one surface of the diffusion sheet 150 to prevent the optical microstructure from being formed. Flatten flat.

Preferably, the surface treatment layer 152 is formed as a flat layer to cover the entire step of the coated optical microstructure 151, thereby eliminating when the optical microstructure 151 of the diffusion sheet 150 is adhered to the resin layer 140 below it. An air layer between a dark space and a bright space caused by a step. Thus, as shown, one of the surface treatment layers is preferably at a height equal to or greater than one of the heights of the optical microstructure. Preferably, the surface treatment layer 152 is basically made of the same material as that of the resin layer 140 to improve the adhesion characteristics.

As shown, at least one light emitting diode source 111 is disposed over the printed circuit board 110 to emit light. According to a preferred embodiment of the invention, a side-emitting light-emitting diode can be used. That is to say, a light source can be used in which the light emitted from the self-illuminating diode light source 111 does not travel straight up, but is advanced toward the side. In addition, the light-emitting diode light source can be set to use the direct-on type of the side-emitting light-emitting diode. Thereby, when the resin layer is used to diffuse and reflect light, the number of light sources is reduced, and the overall thickness of the backlight unit can be remarkably reduced.

The resin layer 140 is stacked to surround the light emitting diode light source 111, and thereby spread light emitted laterally from the light source. That is, the resin layer 140 can perform the function of a conventional light guide plate. Any material, as long as it is a resin and can diffuse light, can be applied to the resin layer. The resin layer according to an embodiment of the present invention may include a resin using urethane acrylate oligomer as a main material. For example, A mixture of an acrylic urethane oligomer and a polymer type of polyacryl as a synthetic oligomer can be used. Of course, the mixture may further comprise a reactive diluent monomer having a low boiling point, such as isobornyl acrylate (IBOA) and hydroxylpropyl acrylate (HPA), 2-hydroxyethyl acrylate (2-HEA); and may comprise a photo initiator such as 1-Hydroxycyclohexyl Phenyl-Ketone, or an antioxidant (antioxidant) as an additive.

In this case, as shown in FIG. 3, the resin layer 140 includes beads 141 to increase diffusion and reflection of light. Preferably, the beads comprise from 0.01 to 0.3% by weight of the overall composition of the resin layer 140. That is, the light emitted from the lateral direction of the self-luminous diode is diffused and reflected by the resin layer 140 and the beads 141, thereby traveling upward. Additionally, reflective film 120 and a reflective microstructure 130 (described in detail below) may facilitate a reflective function. The resin layer significantly reduces the thickness occupied by the conventional light guide plate, thereby achieving the lightness and thinness of the overall product, and includes an elastic material, thereby being versatile, so that the backlight unit can be applied to a flexible Display.

Preferably, the reflective film 120 is made of a reflective material to spread light emitted from the light source; and it is provided with white printing to provide a reflective microstructure 130 to facilitate the spread of light. The reflective microstructure can be printed using a reflective ink comprising either of TiO ₂ and Al ₂ O ₃ .

The function of the diffusion sheet 150 is to diffuse the light emitted by the resin layer 140, and preferably has an optical microstructure 151 to partially shield the light, thereby preventing yellow light from being emitted or avoiding optical characteristics when the light intensity is very strong. Was weakened. That is to say, a light-shielding microstructure can be printed using light-shielding ink to prevent light from being collected.

In addition, the optical microstructure 151 forms a lower surface of the diffusion sheet and is treated by the surface treatment layer 152 to avoid generation of a dark region when the optical microstructure is printed due to the air layer, and to improve the diffusion sheet 150 and the resin layer 140. The adhesion between the two. In particular, for this purpose, the surface treatment layer 152 may be made of the same material as the resin layer 140.

FIG. 5 illustrates a structure in which a diffusion sheet 150 covers an upper portion of each of the light-emitting diode light sources 111, and particularly shows a positional relationship between the light source and the optical microstructure 151. Optical microstructure 151 can be simply printed on or under the diffuser 150. Preferably, the optical microstructure is located in a direction (front) from which light is emitted from the light emitting diode source 111 disposed below the diffuser. That is, the optical microstructure may be formed on the diffusion sheet at a position corresponding to a light-emitting direction or on a vertical upper surface of one of the light-emitting diode light sources.

The optical microstructure 151 according to the present invention may be formed by overlapping printing a diffusion microstructure and a light shielding microstructure into a single layer or a plurality of layers to be formed on a lower surface of the diffusion sheet in a light emitting direction. Here, the diffusion microstructure is printed using a light-shielding ink containing at least one selected from the group consisting of TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and Silicon. The light-shielding microstructure is printed using a light-shielding ink containing a mixture of Al or Al and TiO ₂ .

Figure 6 is a diagram showing an example of forming an optical microstructure in accordance with the present invention.

This example of forming an optical microstructure will be described below in conjunction with the illustration. The optical microstructure 151 can be applied to the lower surface of the diffusion sheet in a light emitting direction by overlapping printing a diffusion microstructure 151a and a light shielding microstructure 151b. The diffusion microstructure 151a is printed using a light-shielding ink containing at least one selected from the group consisting of TiO ₂ , CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and Silicon. The light-shielding microstructure 151b is printed using a light-shielding ink containing a mixture of Al or Al and TiO ₂ . That is, after the diffusion microstructure 151a is formed on the surface of the diffusion sheet by black-and-white printing, the light-shielding microstructure 151b is formed over the diffusion microstructure 151a. Alternatively, such a dual structure can be formed in the reverse order. It will be apparent that designs having such microstructures can vary depending on light efficiency, light intensity, and a light shielding ratio.

In addition, in a sequentially stacked structure, the light-shielding microstructure 151b as a metal microstructure may be formed as an intermediate layer, and the diffusion microstructures 151a may be respectively formed on the upper and lower portions of the light-shielding microstructure 151b. Partially above to provide a triple structure. Such a triple structure can be implemented using the above materials. In a preferred embodiment, one of the diffusion microstructures can be formed using TiO ₂ having a high refractive index, and the other diffusion microstructure can be used with good light stability and color perception ( Color sense) CaCO ₃ and TiO ₂ , and the light-shielding microstructure can be formed using Al having a high light-shielding property, thereby providing a triple structure. Such a structure provides light efficiency and light uniformity. In particular, the CaCO ₃ system can reduce the exposure of yellow light until it is finally implemented as white light, thereby achieving a more stable light efficiency. In addition to CaCO ₃ , inorganic materials such as BaSO ₄ , Al ₂ O ₃ , or Silicon beads, having a large particle size and a similar structure may also be used. Preferably, the optical microstructure is formed to reduce a microstructure density and thereby improve light efficiency when the distance of one of the light-emitting directions of the light-emitting diode source is increased.

The flow of forming an optical microstructure will be described below in conjunction with Figures 7a through 7c.

As shown, the optical microstructures in accordance with the present invention can be printed over the upper or lower surface of the diffuser 150. As shown in Figure 7a, the optical microstructure can be implemented by single tone printing to form a microstructure layer (diffusion microstructure 151a). As shown in Figure 7b, the optical microstructure can be implemented by overlay printing a second microstructure (light-shielding microstructure 151b) over the first microstructure (diffusion microstructure 151a). In addition, as shown in FIG. 7c, the optical microstructure can be implemented by printing the first and second microstructures, and sequentially printing a third microstructure 151c on the first and second microstructures. A triple structure. The overlap printed structure is a structure obtained by forming a microstructure and printing another microstructure on the microstructure.

As shown in FIG. 7a, when the optical microstructure is formed on one surface of the diffusion sheet 150 by monochromatic printing, preferably, the printing is performed using a light-shielding ink containing TiO ₂ to achieve excellent printing. Shading effect and diffusion effect. In this case, the light-shielding ink may use a resin material such as a resin such as an acryl polyol, a hydrocarbon-based or ester-based solvent, and an inorganic pigment such as TiO ₂ . mixture. In particular, an additive such as a silicone-type wetting and dispersing agent or a defoamer/levelling agent may be added to the above materials.

Further, the inorganic pigment may be one or more selected from the group consisting of TiO ₂ or TiO ₂ and selected from the group consisting of CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and silicon.

The inorganic pigment may use a particle diameter of 500 nm to 550 nm. According to an experimental example, the shading ink may comprise 20% to 25% of an acrylic polyol resin; 20% to 29% of a solvent; 50% to 55% of an inorganic pigment; and 1% to 2% of an additive.

Then, in the step shown in FIG. 7b, another optical microstructure according to the present invention can achieve the diffusion microstructure (first microstructure) of light diffusion or light shielding by overlapping printing and can achieve light shielding. The light-shielding microstructure (second microstructure) is formed in a dual structure. That is, after the first microstructure is printed as shown in FIG. 7a, the second microstructure can be formed on the first microstructure by a light-shielding ink comprising a metal-based material. The second microstructure can be printed using a light-shielding ink comprising Al or a mixture of Al and TiO ₂ . Of course, in this case, the first and second microstructures can be stacked in a different order.

The second microstructure is comprised of a metal-based pigment. For example, a light-shielding ink containing a metal base pigment may be used by mixing: a resin such as an acrylic polyol, a hydrocarbon-based or ester-based solvent, a metal base pigment, and an additive such as a hydrazine-containing wetting dispersant, an antifoaming agent, or a Leveling agent, the material produced. The material may have a composition of, for example, 36% to 40% of an acrylic polyol resin; 33% to 40% of a solvent; 20% to 25% of an inorganic pigment; and 1% to 2% of an additive. Alternatively, the solvent may be produced by mixing 10% to 15% of a hydrocarbon-based solvent (having a low boiling point) and 23% to 25% of an ester-based solvent. The second microstructure is a metal microstructure that substantially achieves a light blocking effect.

When forming a stacked structure having two microstructures, the diffusion microstructure and the light shielding microstructure are in the embodiment of the present invention, the first microstructure, that is, the diffusion microstructure, may be selected to include CaCO ₃ , BaSO ₄ , At least one of the group consisting of Al ₂ O ₃ and 矽 is printed with a light-shielding ink.

Further, in the step shown in Fig. 7c, the optical microstructure according to the present invention can be formed in a triple structure by overlapping printing.

That is, the interposer of the optical microstructure can be implemented as a light-shielding microstructure layer having a metal microstructure, and the diffusion microstructure can be formed over the upper surface and the lower surface of the interposer.

As described above, the light-shielding microstructure (second microstructure) as a metal microstructure can be formed using a light-shielding ink containing Al or a mixture of Al and TiO ₂ , and diffused in the step shown in FIG. 7a or 7b. A microstructure is formed over a portion or a lower portion of the light-shielding microstructure.

For example, the first and third microstructures as the outermost microstructure include a diffusion microstructure and are formed to include TiO ₂ or a group selected from CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and yttrium. a light-shielding ink layer of one or more of the groups; or a light-shielding ink layer comprising a mixture of TiO ₂ and CaCO ₃ , BaSO ₄ , Al ₂ O ₃ , and lanthanum. Further, the microstructures (first, second, and third microstructures) forming the optical microstructure each have a thickness of 4 to 100 μm.

Figure 8 is a plan view showing the structure of a reflective film and a reflective microstructure in accordance with the present invention.

Referring to FIG. 8, the reflective film 120 according to the present invention is stacked on a printed circuit board, and the light-emitting diode light source 111 is projected through a hole in the reflective film 120 to the outside. When the light emitting diode light source is implemented as an edge light emitting diode structure, the number of light sources can be significantly reduced as described above. In order to cope with this amount reduction, the reflective microstructures 130 are preferably formed to significantly improve the reflectivity of the light.

As shown in the example of the figure, the reflective microstructure is preferably formed in one of the light-emitting directions of the light-emitting diode source. In particular, the optical microstructure is formed to increase a microstructure density as the distance from one of the illumination directions of the LED source increases. In more detail, the second regions 132, 134 away from the direction of illumination have a microstructure density greater than the microstructure density of the first regions 131, 133 adjacent to the illumination direction to increase reflectivity. Of course, the microstructure can be implemented in a variety of shapes as desired for the design. Alternatively, the reflective microstructure can be formed using a printing process comprising reflective ink comprising either of TiO ₂ and Al ₂ O ₃ .

Figure 9 is a diagram showing the operation of a backlight unit in accordance with the present invention. The operation of the backlight unit will be described in conjunction with Figure 3, which shows the basic structure, and Figure 9, which shows its operation.

As shown in the figure, the backlight unit according to the present invention operates such that light is emitted laterally from the edge-light-emitting diode 111 and is reflected and diffused by the resin layer 140 formed at the position of the conventional light guide plate. Here, the reflection efficiency of the light is further enhanced by the reflection film 120 and the reflective microstructure 130 so that the light energy is guided forward.

The light structure passing through the resin layer 140 is diffused or shielded by the optical microstructure 151 formed on the diffusion sheet 150. The purified light L passes through an optical sheet such as a cymbal sheet 160 and is incident on an LCD panel with a white light. Preferably, a surface treatment layer 152 is provided over the optical microstructures 151 to improve adhesion between the optical microstructures 151 and the resin layer 140, and to remove air layers during adhesion to remove a dark area and improve Reliability.

In this way, the backlight unit according to the present invention can omit the light guide plate, apply the edge light type LED as a light source, and diffuse and reflect the light by the resin layer to guide the light, thereby reducing the number of light sources. And its lightness. In addition, the brightness and uniformity of the light due to the reduction in the number of light sources can be compensated by optical microstructures such as reflective microstructures, light-shielding microstructures, or diffusion microstructures to achieve a uniform image quality.

Further, the step of generating the optical microstructure when the resin layer is bonded to the diffusion sheet can lower the adhesion and form an air layer, thereby producing a dark region. In this case, in order to remove the dark region, the surface treatment layer is added. According to this, a reliable backlight unit can be obtained and can be applied to an LCD.

While the embodiments have been described with reference to the embodiments of the embodiments the embodiments Therefore, the scope of the present invention should be construed as being included in the scope of the appended claims, and all modifications within the scope of the present invention should be construed as being included in the scope of the present invention. within.

1‧‧‧Backlight unit

10‧‧‧Side-light LEDs

20‧‧‧Substrate

30‧‧‧Light guide

31‧‧‧Diffuse film

32‧‧‧ Picture

33‧‧‧ Picture

34‧‧‧Protection film

40‧‧‧reflector

50‧‧‧LCD panel

110‧‧‧Printed circuit board

111‧‧‧Lighting diode source

120‧‧‧Reflective film

130‧‧‧Reflective microstructure

131, 133‧‧‧ first area

132, 134‧‧‧ second area

140‧‧‧ resin layer

141‧‧‧ beads

150‧‧‧Diffuser

151‧‧‧Optical microstructure

151a‧‧‧Diffusion microstructure

151b‧‧‧ shading microstructure

151c‧‧‧ third microstructure

152‧‧‧Surface treatment layer

160‧‧‧ Picture

170‧‧‧protection film

L‧‧‧Light

1 and 2 illustrate the structure of a conventional backlight unit; FIGS. 3 and 4 illustrate an important component of a backlight unit according to the present invention; and FIG. 5 illustrates an optical microstructure and a light-emitting structure of a diffusion sheet according to the present invention. FIG. 6 is a plan view showing an optical microstructure in accordance with the present invention; FIGS. 7a to 7c are diagrams showing an embodiment of manufacturing an optical microstructure according to the present invention; A reflective microstructure is shown; and FIG. 9 illustrates the operation and structure of a backlight unit in accordance with the present invention.

110‧‧‧Printed circuit board

111‧‧‧Lighting diode source

120‧‧‧Reflective film

130‧‧‧Reflective microstructure

140‧‧‧ resin layer

150‧‧‧Diffuser

151‧‧‧Optical microstructure

152‧‧‧Surface treatment layer

160‧‧‧ Picture

170‧‧‧protection film

Claims (16)

A backlight unit includes: a plurality of light emitting diode light sources formed on a printed circuit board; a resin layer stacked on the printed circuit board to embed the light emitting diode light sources therein, and diffusing the light And guiding the forward; and a diffusion sheet having an optical microstructure formed thereon for shielding light emitted from the light emitting diode sources, wherein the optical microstructure comprises: a second microstructure Having a light-shielding microstructure and by overlapping printing on a portion or a lower portion of one of the first microstructures as a diffusion microstructure to diffuse light or shield portions of light, thereby shielding the emitted light Or reflecting; and a third microstructure comprising a diffusion microstructure to encapsulate the first and second microstructures. The backlight unit of claim 1, wherein the first microstructure is a diffusion microstructure and is formed using a light-shielding ink comprising TiO ₂ , CaCO ₃ , BaSO ₄ , Al. At least one of the group consisting of ₂ O ₃ and 矽, or selecting two or more of the above groups. The backlight unit of claim 1, wherein the first microstructure is for diffusing light; and the first microstructure comprises a material comprising TiO ₂ or one of TiO ₂ and CaCO ₃ . The backlight unit of claim 3, wherein one of the first microstructures has a thickness of 4 μm to 100 μm. The backlight unit of claim 1, wherein the second microstructure is formed of a light-shielding ink comprising Al or Al and TiO ₂ . The backlight unit of claim 5, wherein the first and second microstructures further comprise a bead to shield or diffuse the emitted light. The backlight unit of claim 5, wherein one of the second microstructures has a thickness of 4 μm to 100 μm. The backlight unit of claim 1, wherein the third microstructure is formed of a material comprising TiO ₂ or comprising one of TiO ₂ and CaCO ₃ . The backlight unit of claim 8, wherein one of the third microstructures has a thickness of 4 μm to 100 μm. The backlight unit of claim 1, further comprising: a surface treatment layer between the resin layer and the diffusion sheet to accommodate the optical microstructure. The backlight unit of claim 10, wherein the surface treatment layer has a height greater than or equal to a height of the optical microstructure. The backlight unit of claim 11, wherein the surface treatment layer is formed of the same material as the resin layer, and the diffusion sheet is adhered to the resin layer. The backlight unit of claim 1, further comprising: a reflective film having at least one reflective microstructure formed thereon. The backlight unit of claim 13, wherein the reflective microstructure is formed using a reflective ink comprising TiO ₂ or Al ₂ O ₃ . The backlight unit of claim 14, wherein the resin layer further comprises a bead to reflect or diffuse light. A liquid crystal display comprising: the backlight unit according to claim 1; and a liquid crystal display panel on the backlight unit.