KR20090053085A - Backlight unit and liquid crystal display using the same - Google Patents

Abstract

The present invention, a light source; A reflective polarizing film layer positioned above the light source; And a plurality of micro lens layers positioned on the reflective polarizing film layer and having an embossed hemispherical surface.

Reflective polarizing film layer, micro lens layer, liquid crystal display device

Description

Backlight unit and liquid crystal display using the same

The present invention relates to a backlight unit and a liquid crystal display using the same.

With the development of information technology, the market for a display device, which is a connection medium between a user and information, is growing. Accordingly, flat panel displays (FPDs) such as liquid crystal displays (LCDs), organic light emitting diodes (OLEDs), and plasma display panels (PDPs) may be used. Usage is increasing. Among them, a liquid crystal display capable of realizing high resolution and capable of miniaturization as well as a large size is widely used.

Here, the liquid crystal display device is classified into a light receiving display device. Such a liquid crystal display may display an image by receiving a light source from a backlight unit disposed under the liquid crystal panel.

The backlight unit may include a light source and a plurality of optical film layers for enhancing optical characteristics in order to provide efficient light to the liquid crystal panel. Here, the plurality of optical film layers may include a diffusion plate, a diffusion sheet, a prism sheet, a protective sheet, and the like.

Many optical film layers have high optical characteristics due to conditions and structural conditions. Here, the change in the optical characteristics of the plurality of optical film layers affects the light efficiency of the backlight unit and also affects the display quality of the liquid crystal display.

Therefore, in order to improve the display quality of the liquid crystal display device, there is a need to continue research in a number of optical film layer related fields.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems of the background art is to provide a backlight unit capable of improving optical characteristics and a liquid crystal display device using the same.

The present invention as a problem solving means described above, the light source; A reflective polarizing film layer positioned above the light source; And a plurality of micro lens layers positioned on the reflective polarizing film layer and having an embossed hemispherical surface.

The plurality of micro lens layers may include one or more beads.

Light emitted from the light source may be guided by the light guide plate and emitted to the reflective polarizing film layer.

Light emitted from the light source may be guided by the diffusion sheet and emitted to the reflective polarizing film layer.

Light emitted from the light source may be guided by the diffusion plate and emitted to the reflective polarizing film layer.

The lower portion of the reflective polarizing film layer, which is the surface opposite to the surface where the plurality of micro lens layers is located, may have a mat shape.

In another aspect, the present invention, the light source for emitting light; A reflective polarizing film film layer disposed on the light source and a reflective polarizing film film layer disposed on the reflective polarizing film layer and having a plurality of micro lens layers having an embossed hemispherical surface; And a liquid crystal panel displaying an image using light emitted from the light source.

The plurality of micro lens layers may include one or more beads.

The light emitted from the light source may be guided by one or more of the light guide plate, the diffusion plate, and the diffusion sheet, and may be emitted to the reflective polarization lens film layer.

The lower portion of the reflective polarizing film layer, which is the surface opposite to the surface where the plurality of micro lens layers is located, may have a mat shape.

The present invention provides an backlight unit capable of improving optical characteristics and a liquid crystal display device using the same, thereby widening the viewing angle of the liquid crystal display device and improving display quality.

Hereinafter, with reference to the accompanying drawings, the specific content for the practice of the present invention will be described.

<Backlight unit>

The light source used in the present invention may be selected from an edge type in which one lamp is positioned at an end, and a direct type in which a plurality of dual lamps are arranged in a straight line and two lamps are opposed to each other, but not limited thereto.

In addition, the light source may be a Cold Cathode Fluorescent Lamp (CCFL), a Hot Cathode Fluorescent Lamp (HCFL), an External Electrode Fluorescent Lamp (EEFL), or a Light Emitting Diode (Light Emitting Diode): LED) may be any one, but is not limited thereto.

1 is a cross-sectional view of a backlight unit according to a first embodiment of the present invention.

As shown in FIG. 1, the backlight unit according to the first embodiment of the present invention may include a light source 110 that emits light. In addition, the light source 110 may include a reflective polarizer film layer 150. In addition, the reflective polarizing film layer 150 may include a plurality of micro lens layers 160 having an embossed hemispherical surface.

The light source 110 according to the first embodiment has a direct type in which a plurality of lamps are arranged in a straight line in a housing having a reflector plate 130.

On the other hand, the reflective polarizing film layer 150 is shown by stretching the film with different refractive indices in one direction to form a multi-layer thin film structure and laminated so that each stretching direction is matched to transmit only a specific polarization and reflect other light Can function.

Therefore, the reflective polarizing film 150 emits specific light and continuously reflects specific light so that the maximum light can be used without missing light.

Accordingly, in the case of the backlight unit, the light output efficiency of the backlight may be increased by constantly reflecting polarization that has not passed through the polarizing film layer. In addition, by efficiently utilizing the light emitted from the backlight unit it is possible to reduce the power consumption according to the use of the battery and the light source, and to prevent the overheating of the light source can be extended the life of the light source. In the case of the liquid crystal display, the luminance is increased and a wide viewing angle can be obtained.

Hereinafter, the reflective polarizing film layer 150 will be described in more detail with reference to FIG. 2.

FIG. 2 is a cross-sectional view of the reflective polarizing film layer shown in FIG. 1.

As shown in FIG. 2, the reflective polarizing film layer 150 may include a first substrate layer 151, a first resin layer 153, an optical layer 155, a second resin layer 157, and a second substrate. Layer 159.

The optical layer 155 may include a plurality of isotropically oriented layers and anisotropically oriented layers, and the thickness of the optical layer 155 may range from 120 μm to 450 μm, but is not limited thereto. Here, the isotropic alignment layer may be PMMA (Polymethly Methacrylate) having excellent transparency, good weather resistance, high hardness, and excellent surface gloss, but is not limited thereto. The anisotropic alignment layer may be a polyester having a high refractive index. It is not limited to this.

The first base layer 151 and the second base layer 159 may be, but are not limited to, polycarbonate or polyterephthalate. The first resin layer 153 and the second resin layer 157 may be UV (ultra violet) resins, but are not limited thereto.

Meanwhile, the first base layer 151 and the second base layer 159 may include a matte layer 170 that is matted to add a diffusion function as shown, and the mat layer 170 Inside the bead 175 as shown may be included to have a finely convex surface.

Here, although both the first base layer 151 and the second base layer 159 are described in the drawings, one of them may be optionally omitted.

Referring back to FIG. 1, the micro lens layer 160 may be positioned on the reflective polarizing film layer 150 described above.

The microlens layer 160 may be positioned on the reflective polarization film layer 150 to deflect and transmit some of the light light incident from the reflective polarization film layer 150, and reflect the remaining light.

The micro lens layer 160 may be selected from the group consisting of a polymer resin, for example, acrylic, polycarbonate, polypropylene, polyethylene, and polyethylene terephthalate, but is not limited thereto.

The microlens layer 160 may vary in the degree of diffusion, the degree of refraction, the light condensation, etc. according to the size and the density of the lens. Accordingly, the lens diameter of the micro lens layer 160 may be formed to 20 ㎛ ~ 200 ㎛ but is not limited to this, the distribution of the lens occupies the entire area may be formed to have 80% to 90% or more. It is not limited to this.

Meanwhile, a bead may be positioned inside the micro lens layer 160. Hereinafter, the description will be described in more detail with reference to FIGS. 3 and 4.

3 is a view showing a bead located inside the micro lens layer, Figure 4 is a view showing a variety of shapes of the beads.

As shown in FIG. 3, a bead 165 may be located inside the micro lens layer 160.

Referring to FIG. 4A, the beads 165 may have a ball shape. The bead 165 may refract the light incident from the outside twice inside and have a single reflection effect.

Referring to FIG. 4B, the bead 165 may have a snowman shape or a closed curve shape in which two balls are connected. The bead 165 may have an effect of transmitting one side of the light incident from the outside and diffusing the other side.

Referring to FIG. 4C, the beads 165 may have a random shape. The bead 165 may also have a reflection effect of refraction and reflection of light incident from the outside at various angles.

Referring to FIG. 4D, the bead 165 may have a small bead 166 therein. The bead 165 may also have a reflection effect of refraction and reflection of light incident from the outside at various angles.

On the other hand, unlike shown, the small beads 166 included in the interior of the bead 165 may be exposed to the outside. In addition, the inside of the bead 165 may be divided into upper and lower portions, and the small beads 166 may be formed in the inside of the bead 165 at different specific gravity.

Referring back to FIG. 1, the backlight unit may include one or more of the diffusion plate 180 or the diffusion sheet 190.

The diffusion plate 180 may serve to guide the light emitted from the light source 110 to be uniformly diffused into the reflective polarizing film layer 150. The diffusion plate 180 may use a high purity acrylic resin or the like, but is not limited thereto.

The diffusion sheet 190 may serve to guide the light emitted from the light source 110 to the reflective polarization film layer 150 evenly and uniformly, and may achieve overdiffusion, high transparency, and high light condensation. have. The material of the diffusion sheet 190 may be, for example, polyester, polycarbonate, and the like, but is not limited thereto.

5 is a cross-sectional view of a backlight unit according to a second embodiment of the present invention.

As shown in FIG. 5, the backlight unit according to the second embodiment of the present invention may include a light source 210 for emitting light. In addition, the reflective polarizer film layer 250 may be included on the light source 210. In addition, the reflective polarizing film layer 250 may include a plurality of micro lens layers 260 having an embossed hemispherical surface.

The light source 210 according to the second embodiment has an edge type in which one lamp is positioned in the housing 220 having the reflecting plate, and the light guide plate 140 that guides the light emitted from the light source 210 is included.

On the other hand, the reflective polarizing film layer 250 is shown by stretching the film having different refractive indices in one direction to form a multi-layer thin film structure and laminated so that each stretching direction is matched to transmit only specific polarized light and other light is reflected Can function.

Therefore, the reflective polarizing film 250 may emit specific light and continuously reflect the specific light so that the maximum light can be used without missing light.

Accordingly, in the case of the backlight unit, the light output efficiency of the backlight may be increased by constantly reflecting polarization that has not passed through the polarizing film layer. In addition, by efficiently utilizing the light emitted from the backlight unit it is possible to reduce the power consumption according to the use of the battery and the light source, and to prevent the overheating of the light source can be extended life of the light source. In the case of the liquid crystal display, the luminance is increased and a wide viewing angle can be obtained.

As described with reference to FIG. 2, the reflective planar film layer 250 may include a first substrate layer, a first resin layer, an optical layer, a second resin layer, and a second substrate layer. In addition, a matte treated matte layer may be positioned below the reflective polarizing film layer 250.

Meanwhile, the micro lens layer 260 may be positioned on the reflective polarizing film layer 250.

The micro lens layer 260 may be positioned on the reflective polarization film layer 250 to deflect and transmit some of the light light incident from the reflective polarization film layer 250, and reflect the remaining light.

The micro lens layer 260 may be selected from the group consisting of a polymer resin, for example, acrylic, polycarbonate, polypropylene, polyethylene, and polyethylene terephthalate, but is not limited thereto.

The microlens layer 260 may vary in the degree of diffusion, the degree of refraction, the light collecting property, and the like, depending on the size and the density of the lens. Accordingly, the lens diameter of the micro lens layer 260 may be formed to 20 ㎛ ~ 200 ㎛ but is not limited thereto. In the case of the micro lens layer 260, the distribution of the lens in the total area may be formed to have 80% to 90% or more, but is not limited thereto.

Beads may be located inside the micro lens layer 260 as described with reference to FIGS. 3 and 4. Accordingly, the bead located in the micro lens layer 260 may be variously selected to any one of (a) to (d) of FIG.

The backlight unit may include at least one of the diffusion plate 280 and the diffusion sheet 290.

The diffusion plate 280 may serve to guide the light emitted from the light source 210 to be uniformly diffused into the reflective polarizing film layer 250. The diffusion plate 280 may use a high purity acrylic resin or the like, but is not limited thereto.

The diffusion sheet 290 may serve to guide the light emitted from the light source 210 to the reflective polarization film layer 250 evenly and uniformly, and may achieve overdiffusion, high transparency, and high light condensation. have. In addition, the diffusion sheet 290 may be formed of a material such as opaque glass to serve to hide the dots of the light guide plate 140. The material of the diffusion sheet 290 may be, for example, polyester, polycarbonate, etc., but is not limited thereto.

<LCD display device>

Meanwhile, in another aspect, the present invention may provide a liquid crystal display device using the prism sheet described above.

6 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 7 is a cross-sectional view of the reflective polarization lens film layer shown in FIG. 6.

As shown in FIG. 6, the LCD may include a light source 340 that emits light. In addition, the reflective polarization film layer disposed on the light source 340 and the reflective polarization lens film layer 333 disposed on the reflective polarization film layer and a plurality of micro lens layers having an embossed hemispherical surface are disposed. It may include. In addition, the liquid crystal panel 320 may display an image by using light emitted from the light source 340.

Here, the light source 340 and the reflective polarization lens film layer 333 may be included in the backlight unit.

The illustrated light source 340 represents a direct type in which a plurality of lamps are arranged in a straight line. However, the light source 340 may select any one of an edge type in which the lamp is located at one side outside, and a dual type in which the lamp is located at both sides, but is not limited thereto. The light source 340 as described above may be connected to an inverter to receive power by emitting power.

Here, the light source 340, for example, Cold Cathode Fluorescent Lamp (CCFL), Hot Cathode Fluorescent Lamp (HCFL), External Electrode Fluorescent Lamp (EEFL) ) And a light emitting diode (LED) may be selected, but is not limited thereto.

Referring to FIG. 7, the reflective polarization lens film layer 333 may include a first base layer 333a, a first resin layer 333b, an optical layer 333c, a second resin layer 333d, and a second base layer. The reflective polarizing film layer 333a, 333b, 333c, 333d, and 333e including the 333e and the reflective polarizing film layer 333a, 333b, 333c, 333d, and 333e are disposed on the reflective polarizing film layer 333a. , 333b, 333c, 333d, and 333e may be partially refracted and transmitted, and the remaining light may include a plurality of micro lens layers 333f upon reflection.

Here, the optical layer 333c included in the reflective polarizing film layers 333a, 333b, 333c, 333d, and 333e may include a plurality of isotropically oriented layers and anisotropically oriented layers, and an optical layer 333c. ) May have a thickness of 120 μm to 450 μm, but is not limited thereto.

Here, the isotropic alignment layer may be PMMA (Polymethly Methacrylate) having excellent transparency, good weather resistance, high hardness, and excellent surface gloss, but is not limited thereto. The anisotropic alignment layer may be a polyester having a high refractive index. It is not limited to this. The first base layer 333a and the second base layer 333e may be polycarbonate or polyterephthalate, but are not limited thereto. The first resin layer 332b and the second resin layer 332d may be UV resins, but are not limited thereto.

Here, the first base layer 333a and the second base layer 333e may include a matte layer 333g which is matted to add a diffusion function as described above, and the mat layer 333g. The inside of the beads 333h may include a finely convex surface.

Here, the micro lens layer 333f may be selected from the group consisting of a polymer resin, for example, acrylic, polycarbonate, polypropylene, polyethylene, and polyethylene terephthalate, but is not limited thereto. The microlens layer 333f may vary in the degree of diffusion, the degree of refraction, the light collecting property, and the like, depending on the size and the density of the lens.

Accordingly, the lens diameter of the micro lens layer 333f may be formed to 20 μm to 200 μm, but is not limited thereto. In addition, the microlens layer 333f may be formed such that the distribution of the lens in the total area is 80% to 90% or more, but is not limited thereto.

Although not shown, the beads may be located inside the micro lens layer 333f. The beads may be selected from any one of (a) to (d) of FIG. 4 described above.

The LCD may include a liquid crystal panel 320 displaying an image, and an upper case 310 and a lower case 370 in which the light source 340 is accommodated.

Here, the lower case 370 may receive the light source 340. The liquid crystal panel 320 may be positioned at a predetermined interval on the light source 340. The liquid crystal panel 320 and the light source 340 may be fixed and protected by the upper case 310 coupled to the lower case 370.

An opening for exposing the image display area of the liquid crystal panel 320 may be provided on an upper surface of the upper case 310. In addition, a mold frame (not shown) may be further included on the periphery of the plurality of optical film layers 330 positioned between the liquid crystal panel 320 and the light source 340.

The liquid crystal panel 320 may have a structure in which an upper plate 322 having a color filter and a lower plate 321 having a thin film transistor are bonded to each other with a liquid crystal interposed therebetween. In the liquid crystal panel 320, subpixels driven independently by a thin film transistor are arranged in a matrix form, and a difference between a common voltage supplied to each common pixel and a data signal supplied to the pixel electrode through the thin film transistor is provided. The image can be displayed by controlling the liquid crystal array in accordance with the voltage to adjust the light transmittance.

In addition, the driving unit 325 may be connected to the lower plate 321 of the liquid crystal panel 320. The driver 325 is mounted with a driving chip 327 for driving the data line and the gate line of the liquid crystal panel 320, respectively, a plurality of film circuits 326 having one side connected to the lower plate 321, and a plurality of films. The printed circuit board 328 may be connected to the other side of the circuit 326.

The film circuit 326 in which the driving chip 327 is mounted represents a chip on film (COF) or a tape carrier package (TCP) method. Alternatively, the driving chip 327 may be directly mounted on the lower plate 321 by a chip on glass (COG) method or may be formed and embedded on the lower plate 321 in a thin film transistor forming process.

The reflective polarization lens film layer 333 described above may be included in the plurality of optical film layers 330. The plurality of optical film layers 330 may further include not only the reflective polarization lens film layer 333 but also a diffusion plate 331, a diffusion sheet 332, a protective sheet 334, and the like as shown. Therefore, the backlight unit may further include a light source 340, a diffusion plate 331, a diffusion sheet 332, a reflective polarization lens film layer 333, a protective sheet 334, and the like.

The liquid crystal panel 320 described above may display an image on each pixel according to a scan signal supplied through the gate lines and a data voltage supplied through the data lines.

Here, the scan signal may be a pulse signal in which the gate high voltage supplied only for one horizontal time and the gate low voltage supplied for the remaining time are alternated.

The thin film transistor included in the pixel may be turned on when the gate high voltage is supplied from the gate lines to supply the data voltage applied from the data lines to the liquid crystal cell.

The liquid crystal cell may be formed between the pixel electrode supplied with the data voltage from the data lines and the common electrode applied with the common voltage.

Accordingly, when the thin film transistor of each pixel is turned on and the data voltage is applied to the pixel electrode, the liquid crystal display may display an image while charging the difference voltage between the data voltage and the common voltage in the liquid crystal cell.

On the contrary, when the gate low voltage is supplied from the gate lines, the thin film transistor is turned off and the data voltage charged in the liquid crystal cell can be maintained by the storage capacitor for one frame period.

As such, the liquid crystal panel 320 may repeat different operations according to scan signals supplied through the gate lines.

As described above, in the case of the backlight unit, the light output efficiency of the backlight may be increased by constantly reflecting polarization that has not passed through the polarizing film layer. In addition, by efficiently utilizing the light emitted from the backlight unit it is possible to reduce the power consumption according to the use of the battery and the light source, and to prevent the overheating of the light source can be extended the life of the light source. In the case of the liquid crystal display, the luminance is increased and a wide viewing angle can be obtained.

That is, the present invention can improve the optical characteristics of the backlight unit and can widen the viewing angle of the liquid crystal display device, thereby improving display quality.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention described above may be modified in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

1 is a cross-sectional view of a backlight unit according to a first embodiment of the present invention.

2 is a cross-sectional view of the reflective polarizing film layer shown in FIG.

3 is a view showing a bead located inside the microlens layer.

4 shows various shapes of beads.

5 is a cross-sectional view of a backlight unit according to a second embodiment of the present invention.

6 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

7 is a cross-sectional view of the reflective polarizing lens film layer shown in FIG.

<Explanation of symbols on main parts of the drawings>

110 and 210: light source 150 and 250: reflective polarizing film layer

160, 260: microlens layer 180, 280: diffuser plate

190, 290: Diffusion sheet

Claims (10)

Light source; A reflective polarizing film layer positioned above the light source; And And a plurality of micro lens layers positioned on the reflective polarizing film layer and having a hemispherical surface having an embossed surface. The method of claim 1, The plurality of micro lens layers, A backlight unit comprising one or more beads. The method of claim 1, The light emitted from the light source is guided by the light guide plate and is emitted to the reflective polarizing film layer. The method of claim 1, The light emitted from the light source is guided by the diffusion sheet is emitted to the reflective polarizing film layer. The method of claim 1, The light emitted from the light source is guided by the diffusion plate is emitted to the reflective polarizing film layer. The method of claim 1, The lower portion of the reflective polarizing film layer, which is opposite to the surface on which the plurality of micro lens layers are located, has a mat shape. Light source; A reflective polarization lens film layer disposed on the light source, and a reflective polarization lens film layer disposed on the reflective polarization film layer and having a plurality of micro lens layers having an embossed hemispherical surface; And And a liquid crystal panel for displaying an image by using the light emitted from the light source. The method of claim 7, wherein The plurality of micro lens layers, Liquid crystal display comprising at least one bead. The method of claim 7, wherein The light emitted from the light source is A liquid crystal display device which is guided by at least one of a light guide plate, a diffusion plate, and a diffusion sheet and exits the reflective polarization lens film layer. The method of claim 7, wherein The lower portion of the reflective polarizing film layer, which is a surface opposite to the surface on which the plurality of micro lens layers are positioned, has a mat shape.

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