KR20080032506A - Backlight unit and liquid crystal display using the same - Google Patents

Abstract

A backlight unit and an LCD using the same are provided to simplify a manufacturing process by manufacturing an LED unit through a COB(Chip On Board) method, reduce manufacturing costs by integrally forming a reflection plate on a substrate, and minimize interference between LEDs by forming a polyhedral molding unit for sealing the LEDs. Plural LEDs(Light Emitting Diodes)(230a,230b,230c) are mounted on a substrate. Plural polyhedral molding units(250) respectively seal at least one or more LEDs. A reflection layer(220) is formed between the plural polyhedral molding units. Interference between the LEDs of unit of the polyhedral molding unit is minimized by refracting light sidewardly emitted from the LED through full reflection.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY USING THE SAME}

1 is a schematic perspective view of a backlight unit according to the present invention;

2 is a schematic plan view of a backlight unit according to the present invention;

3 is a schematic cross-sectional view taken at line A-A of FIG.

4 is a schematic plan view of a backlight unit according to a modification of the present invention;

5 is a diagram for explaining a critical angle.

6 is an exploded perspective view of a liquid crystal display using the backlight unit according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: lower housing member 210: substrate

220: reflective layer 230: light emitting diode

250: polyhedral molding

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a liquid crystal display using the same, and more particularly, to a backlight unit having a chip on board type light emitting diode unit having a polyhedral molding and a liquid crystal display using the same.

In general, the liquid crystal display (LCD) has been expanding its application range due to features such as light weight, thinness, low power driving, full color, and high resolution. Currently, liquid crystal displays are used in computers, notebooks, PDAs, telephones, TVs, and audio / video devices. Such a liquid crystal display displays a desired image on a liquid crystal display panel in which light transmittance is adjusted according to image signals applied to a plurality of control switches arranged in a matrix form.

The liquid crystal display device includes a backlight unit provided under the liquid crystal display panel and the liquid crystal display panel to supply light to the liquid crystal display panel. In this case, the backlight unit according to the related art may be classified into an edge type type in which a light source is located on a side of the liquid crystal display panel, and a direct type type in which a light source is located on a lower surface of the liquid crystal display panel. In addition, the direct type may have a different shape according to the type of light source, and the local dimming LEDs (LDL) backlight unit using the light emitting diode among the direct type may include a plurality of light emitting diodes on a substrate. It is mounted on the bottom surface of the liquid crystal display panel.

However, in the backlight unit according to the related art, interference occurs as a plurality of light emitting diodes are arranged at close intervals, and accordingly, light emitted from light emitting diodes of a close distance overlaps with each other so that a high contrast ratio of natural dimming is inherent. It does not take advantage of (Contrast Ratio) and clear picture quality.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a backlight unit having a local dimming structure and a liquid crystal display using the same, which can minimize interference effects between light emitting diodes.

Another object of the present invention is to provide a backlight unit and a liquid crystal display using the same, which can simplify the manufacturing process by minimizing the assembly structure of the backlight unit.

In order to achieve the above-described paragraph, the present invention provides a substrate, a plurality of light emitting diodes mounted on the substrate, a plurality of polyhedral molding portions encapsulating the at least one light emitting diode, and the plurality of polyhedral molding portions. It provides a backlight unit comprising a reflective layer formed. In this case, it is preferable that the plurality of polyhedral molding parts have a polygonal column shape wider than the lower part thereof, and the adjacent polyhedral molding parts contact each other. In addition, the light emitting diode may include red, green, and blue light emitting diodes, and the reflective layer may include an epoxy resin or a silicone resin mixed with a white reflective material. The white reflective material may include titanium oxide (TiO ₂ ).

The present invention also includes a substrate, a plurality of light emitting diodes mounted on the substrate, a plurality of polyhedral molding portions encapsulating the at least one light emitting diode, and a reflective layer formed between the plurality of polyhedral molding portions. A backlight unit; And a liquid crystal display panel displaying an image using light supplied from the backlight unit. In this case, the plurality of polyhedral molding parts may have a polygonal column shape wider than a lower portion thereof, and the adjacent polyhedral molding parts may contact each other, and the reflective layer may include an epoxy resin or a silicone resin mixed with a white reflective material.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like reference numerals in the drawings refer to like elements.

1 is a schematic perspective view of a backlight unit according to the present invention, FIG. 2 is a schematic plan view of the backlight unit according to the present invention, FIG. 3 is a schematic cross-sectional view taken at the line AA of FIG. 2, and FIG. 4 is a modification of the present invention. Is a schematic plan view of a backlight unit according to the present invention, and FIG. 5 is a diagram for describing a critical angle.

1 to 3, the backlight unit 1000 according to the present invention includes a light emitting diode unit 200 having a light emitting diode 230, a reflective layer 220, and a polyhedral molding part 250. In this case, the backlight unit 1000 according to the present invention includes a plurality of optical sheets 310 and 320, a light emitting diode unit 200, and a plurality of optical sheets 310 and 320 on the light emitting diode unit 200. It may further include a lower receiving member 100 for receiving.

The light emitting diode unit 200 reflects a substrate 210, a light emitting diode 230 mounted on the substrate 210, and light emitted from the light emitting diode 230 formed on the substrate 210. And a polyhedral molding part 250 for encapsulating the light emitting diode 230.

The substrate 210 is for applying external power to the light emitting diode 230 and quickly discharging heat generated when the light emitting diode 230 is operated to the outside, and includes a printed circuit board (PCB) and metal shim printing. It may include a metal core printed circuit board (MCPCB), FR4, BT resin (Bismaleimide Triazine Resin; BT Resin) and the like. In this embodiment, a printed circuit board will be described as an example. In this case, a light emitting diode 230 is mounted on an upper surface of the substrate 210 according to the present invention, and a reflective layer 220 is formed between the light emitting diodes 230. In addition, the substrate 210 according to the present invention may apply power to the light emitting diode 230 under the substrate 210. As described above, a through hole 212 may be formed in the substrate 210 according to the present invention in order to apply power from the lower portion of the substrate 210. The inner circumference of the through hole 212 may be formed of the conductor 214. The upper and lower portions of the substrate 210 may be connected by coating. In this case, in the present invention, the through hole 212 and the light emitting diode 230 may be connected by two wires, and the through hole 212 may include first and second through holes 212a and 212b. . In addition, the first and second through holes 212 may include first and second conductors 214a and 214b coated.

The light emitting diode 230 is a compound semiconductor stacked structure having a p-n junction structure and uses a phenomenon in which light is emitted by recombination of minority carriers (electrons or holes). The light emitting diodes may include first and second semiconductor layers (not shown) and active layers (not shown) formed between the first and second semiconductor layers. In this embodiment, the first semiconductor layer is a P-type semiconductor layer, and the second semiconductor layer is an N-type semiconductor layer. In addition, a first electrode (not shown), that is, a P-type electrode is formed on one surface of the P-type semiconductor layer of the light emitting diode 230, and a second electrode (not shown), that is, an N-type, on one surface of the N-type semiconductor layer An electrode is formed. In this case, the N-type electrode is connected to the first conductor 212a by the first wiring 240a, and the P-type electrode is electrically connected to the second conductor 212b by the second wiring 240b. Can be. However, the present invention is not limited thereto, and the light emitting diode 230 according to the present invention may use a vertical light emitting diode in addition to the horizontal light emitting diode as described above, and may use various types of light emitting diodes that emit visible light or ultraviolet light. . In the present embodiment, the light emitting diode 230 may emit white light using the first to third light emitting diodes 230a, 230b, and 230c which emit red (R), green (G), and blue (B). have. That is, the backlight unit 1000 according to the present invention uses the first to third light emitting diodes 230a, 230b, and 230c which emit red (R), green (G), and blue (B) as one set, respectively. The polyhedral molding part 250 is formed to encapsulate the first to third light emitting diodes 230a, 230b, and 230c. In addition, the first to third light emitting diodes 230a, 230b, and 230c include first and second electrodes, respectively, and the first and second electrodes respectively include first and second wirings 240a and 240b, respectively. It may be connected to the first and second conductors (214a, 214b) by. However, the present invention is not limited thereto, and the connection between the light emitting diode 230 and the substrate 210 may vary depending on the type of the substrate 210. In addition, the backlight unit 1000 according to the present invention may mount a light emitting diode package having the light emitting diode 230 mounted therein without mounting the light emitting diode 230 on the substrate 210. That is, the light emitting diode may be built-in therein, and a light emitting diode package having a structure including a lead frame connected thereto may be mounted on a substrate to apply power to the light emitting diode through the lead frame.

The reflective layer 220 is for injecting light emitted from the light emitting diode 230 into the upper portion, that is, the liquid crystal display panel, and may be formed on the upper surface of the substrate 210. The reflective layer 220 may be formed between a plurality of polyhedral structure molding parts to reflect the light emitted from the light emitting diodes 230 to the top to increase light utilization efficiency. In addition, the reflection amount of the entire incident light may be adjusted so that the entire light emitting surface of the backlight unit 1000 may have a uniform luminance distribution. The reflective layer 220 may be formed of an epoxy resin or a silicone resin in which a white-colored resin, for example, titanium oxide (TiO ₂ ) is mixed. The backlight unit 1000 according to the present invention does not need to provide a reflective plate by forming the reflective layer 220 on the substrate 210 on which the light emitting diode 230 is mounted as described above. Therefore, the manufacturing cost of the backlight unit 1000 may be reduced, and the manufacturing process may also be simplified.

The polyhedral molding part 250 is to encapsulate a light emitting diode and to fix a wire connected to the light emitting diode, and may be formed in a transfer mold method using a mold press. In addition, the molding part may be formed in a specific shape to encapsulate the light emitting diode and to fix the wiring, as well as to control the path of the light emitted from the light emitting diode. Since the molding part has to transmit the light emitted from the light emitting diode to the outside, it is usually formed of a light transmissive resin.

In the present exemplary embodiment, the polyhedral molding part 250 is formed into a polyhedral structure as shown in FIGS. 1 and 2 to encapsulate the first to third light emitting diodes 230a, 230b, and 230c, and the first to third light emitting diodes 230a, 230b, and 230c. The light emitted from the third light emitting diodes 230a, 230b and 230c is emitted from the adjacent first to third light emitting diodes 230a, 230b and 230c by the relationship between the incident angle and the critical angle due to the shape of the polyhedral structure molding part. The light may be incident to the liquid crystal display panel (not shown) without being interfered with.

The polyhedral molding part 250 according to the present exemplary embodiment has an octagonal pillar shape having side surfaces of an octagonal surface, and is formed such that an upper portion thereof is wider than a lower portion so that light emitted from the light emitting diodes 230 can totally reflect. In this case, the shape of the polyhedral molding part 250 according to the present invention may vary depending on the orientation angle of the light emitting diode. That is, the inclination of the side surface of the surface of the polyhedral molding part 250 and the width of the top and bottom of the polyhedral molding part 250 may vary according to the direction of the light emitting diode.

In addition, when a plurality of polyhedral molding parts 250 are formed, it is preferable that one surface of adjacent polyhedral molding parts 250 is in contact with each other, and the plurality of polyhedral molding parts 250 are arranged in a matrix form for uniform luminance distribution. It is desirable to be. Of course, the polyhedral molding part 250 may be arranged irregularly.

However, the present invention is not limited thereto, and the polyhedral molding part 250 may have a hexagonal pillar shape as shown in FIG. 4 (a) or may have a square pillar shape as shown in FIG. In this case, the backlight unit 1000 according to the modification of the present invention shown in FIGS. 4A and 4B also contacts the polyhedral molding part 250 in which one surface of the polyhedral molding part 250 is adjacent to each other. Preferably, when a plurality of polyhedral moldings 250 are formed, they are preferably arranged in a matrix form. Since the polyhedral molding part 250 is closer to the cylinder, the light efficiency is higher, so that the polyhedral molding part 250 according to the present invention has a larger side angle.

Referring to FIG. 5, the critical angle refers to the value of the incident angle θc at which total reflection occurs at larger angles when light is incident from the large refractive index material n ₁ to the small material n ₂ . That is, as shown in (a) of FIG. 5, when light meets and refracts another medium n ₂ <n ₁ , the incident angle at which the refractive angle is 90 degrees is referred to as a critical angle, and the incident angle is measured based on a normal line. It refers to one angle (theta) c1. If the angle of incidence is greater than the critical angle, total reflection occurs.

Accordingly, in the present invention, as shown in (b) of FIG. 5, light is incident vertically from one medium (n ₁ ) to the other medium (n ₂ ) in _two media having different refractive indices (n ₂ <n ₁ ). In this case, when the boundary surface of the medium n ₁ has a predetermined slope, the angle formed by the incident light and a normal perpendicular to the boundary surface becomes larger than the critical angle θ c2> θ c1. This light is unable to proceed to the other medium (n ₂₎ to be transmitted through the medium (n _1), is reflected into the working medium (n _1). When the total reflection phenomenon of light is used, the light is not transmitted but reflects the transparent surface. Here, as one medium, a material having excellent light transmittance such as the polyhedral molding part 250 according to the present invention may be used, and the other medium may be, for example, air.

Therefore, light emitted from the side surface of the light emitting diode 230 among the light emitted from the light emitting diode 230 by using the optical property is directed upward by the total reflection caused by the octagonal face of the polyhedral molding part 250. Can be.

As described above, the backlight unit 1000 according to the present invention includes a chip, which is one of surface mounting techniques, of the light emitting diode unit 200 including a substrate 210, a light emitting diode 230, a reflecting plate, and a polyhedral molding part 250. The manufacturing process can be simplified by fabricating in a chip on board (COB) method and applying it to the backlight unit 1000 without a separate assembly process. In addition, it is possible to reduce the manufacturing cost by integrally formed on the substrate 210 without having a separate reflection plate.

Furthermore, the backlight unit 1000 according to the present invention forms a polyhedral molding part 250 encapsulating the light emitting diode 230, thereby refracting the light emitted from the light emitting diode 230 to the side by total reflection phenomenon. Interference between the light emitting diodes 230 in units of 250 may be minimized.

Meanwhile, the plurality of optical sheets 310 and 320 include a diffusion sheet 310 and a prism sheet 320, which are disposed on the light emitting diode unit 200 to uniform the luminance distribution of the emitted light. The diffusion sheet 310 directs the light incident from the light emitting diode unit 200 toward the front of the liquid crystal display panel, and diffuses the light to have a uniform distribution in a wide range so that the liquid crystal display panel is irradiated. The prism sheet 320 serves to change the light incident at an oblique angle among the light incident on the prism sheet to be emitted vertically.

The lower accommodating member 100 may be formed in a box shape of a rectangular parallelepiped in which an upper surface thereof is opened, and an accommodating space having a predetermined depth may be formed inside. The lower accommodating member 100 may include a bottom surface and sidewalls extending vertically from each edge from the bottom surface.

Next, a liquid crystal display using the backlight unit 1000 according to the present invention will be described. The liquid crystal display according to the present invention described below will be mainly described with a configuration different from that of the backlight unit 1000 described above, and other descriptions of the above-described backlight unit 1000 will be omitted.

6 is an exploded perspective view of a liquid crystal display using the backlight unit 1000 according to the present invention.

Referring to FIG. 6, a liquid crystal display according to the present invention includes a backlight unit including a liquid crystal display panel 2200, a substrate 210, a light emitting diode 230, a reflective layer 220, and a polyhedral molding part 250. 1000, a mold frame 2000 for accommodating the backlight unit 1000, a liquid crystal display panel 2200, and an upper accommodating member 2400 for enclosing predetermined regions and sides of the backlight unit 1000. do.

In the above, the liquid crystal display panel 2200 may include a thin film transistor substrate 2220, a data side and gate side tape carrier package (TCP) 2260a and 2280a connected to the thin film transistor substrate 2220, and data. Data side and gate side printed circuit boards 2260b and 2280b connected to the side and gate side tape carrier packages 2260a and 2280a, respectively, a color filter substrate 2240 corresponding to the thin film transistor substrate 2220, and a thin film transistor. And a liquid crystal layer (not shown) injected between the substrate 2220 and the color filter substrate 2240. In addition, the display device may further include a polarizer (not shown) formed to correspond to the upper portion of the color filter substrate 2240 and the lower portion of the thin film transistor substrate 2220, respectively.

The color filter substrate 2240 is a substrate in which red (R), green (G), and blue (B) pixels, which are color pixels in which a predetermined color is expressed while light passes, are formed by a thin film process. A common electrode (not shown) made of a transparent conductor such as indium tin oxide (ITO) or indium zinc oxide (IZO), which is a transparent conductive thin film, is formed on the front surface of the color filter substrate 2240. have.

The thin film transistor substrate 2220 is a transparent glass substrate in which thin film transistors (TFTs) and pixel electrodes are formed in a matrix form. The data line is connected to the source terminal of the thin film transistors, and the gate line is connected to the gate terminal. Also, a pixel electrode (not shown) made of a transparent electrode made of a transparent conductive material is connected to the drain terminal. When an electrical signal is input to the data line and the gate line, each thin film transistor is turned on or turned off to apply an electrical signal necessary for pixel formation to a drain terminal.

The backlight unit 1000 may include a light emitting diode unit 200 for generating light, a plurality of optical sheets 310 and 320 disposed on the light emitting diode unit, a light emitting diode unit 200, and a plurality of optical fibers. A lower accommodating member 100 for accommodating the sheets 310 and 320 and a driving unit (not shown) for driving the light emitting diode unit 200 may be included.

As described above, the backlight unit 1000 according to the present invention is a chip on board (COB) method in which a light emitting diode unit 200 including a substrate, a light emitting diode, a reflecting plate, and a polyhedral molding part is one of surface mounting technologies. It is possible to simplify the manufacturing process by applying the same to the backlight unit 1000 without a separate assembly process. In addition, it is possible to reduce the manufacturing cost by integrally formed on the substrate 210 without having a separate reflection plate. In addition, the backlight unit 1000 according to the present invention forms a polyhedral molding part encapsulating the light emitting diode, thereby refracting the light emitted from the light emitting diode side by total reflection phenomenon to minimize the interference between the light emitting diodes in the unit of the polyhedral molding part. Can be.

The mold frame 2000 is formed in a rectangular frame shape and includes a planar portion and sidewall portions bent at right angles therefrom. A mounting portion (not shown) may be formed on the flat portion to allow the liquid crystal display panel 2200 to be mounted thereon. The seating part may use a fixing protrusion for contacting and aligning the edge side surfaces of the liquid crystal display panel 2200, respectively, or may be formed using a predetermined stepped step surface. A plurality of optical sheets 310 and 320 and the light emitting diode unit 200 are fixed to the mold frame 2000 between the lower housing member 100.

The upper accommodating member 2400 is configured in the form of a rectangular window frame having a flat portion and sidewall portions bent at right angles therefrom. The planar portion of the upper accommodating member 2400 may support a portion of the edge of the liquid crystal display panel 2200 at a lower portion thereof, and the side wall portion may be coupled to face the sidewalls of the lower accommodating member 100. The upper accommodating member 2400 and the lower accommodating member 100 may be manufactured using metal having excellent strength, light weight, and low deformation.

Although described above with reference to the drawings and embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit of the invention described in the claims below. I can understand.

As described above, the present invention may provide a backlight unit having a local dimming structure and a liquid crystal display device using the same to form a polyhedral molding part encapsulating a light emitting diode to minimize interference effects between the light emitting diodes.

In addition, the present invention can provide a backlight unit and a liquid crystal display device using the same, which can simplify the manufacturing process by minimizing the assembling structure of the backlight unit by providing a chip on board light emitting diode unit having a reflective layer.

Claims (8)

Substrate, A plurality of light emitting diodes mounted on the substrate; A plurality of polyhedral molding portions encapsulating the at least one light emitting diode, respectively; And a reflective layer formed between the plurality of polyhedral molding parts. The method according to claim 1, And a plurality of polyhedral molding parts having a polygonal column shape wider than a lower part thereof, and adjacent polyhedral molding parts contact each other. The method according to claim 1, And the light emitting diodes comprise red, green, and blue light emitting diodes. The method according to claim 1, The reflective layer is a backlight unit, characterized in that the epoxy resin or silicone resin mixed with a white reflective material. The method according to claim 4, The white reflector includes titanium oxide (TiO ₂ ). Substrate, A plurality of light emitting diodes mounted on the substrate; A plurality of polyhedral molding portions encapsulating the at least one light emitting diode, respectively; A backlight unit including a reflective layer formed between the plurality of polyhedral molding parts; And And a liquid crystal display panel which displays an image by using light supplied from the backlight unit. The method according to claim 6, And the plurality of polyhedral molding parts have a polygonal column shape wider than a lower part thereof, and the adjacent polyhedral molding parts contact each other. The method according to claim 6, And the reflective layer comprises an epoxy resin or a silicone resin mixed with a white reflective material.

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