KR20070074889A - Back light unit and liquid crystaldisplay device using the same - Google Patents

Abstract

A backlight unit and an LCD using the same are provided to prevent the loss of light and improve the light efficiency, by forming a reflecting unit around an LED(Light Emitting Diode) element. A backlight unit(112) comprises a light guiding plate(120), an LED element installed at a first side of the light guiding plate, and a reflecting unit(122) installed at a second side of the light guiding plate except a light exit portion. The reflecting unit has concave and convex patterns. The reflecting unit is disposed above the light emitting diode. The reflecting unit is a silver sheet. The concave and convex patterns are formed in an embossing type or mountain configurations.

Description

BACK LIGHT UNIT AND LIQUID CRYSTALDISPLAY DEVICE USING THE SAME}

1 is a cross-sectional view showing a conventional liquid crystal display device.

2 is an exploded perspective view showing a liquid crystal display according to the present invention.

3 is a cross-sectional view taken along line A-A of the liquid crystal display according to the present invention.

4 to 6 are cross-sectional views illustrating a liquid crystal display according to another exemplary embodiment of the present invention.

           <Description of the code | symbol about the principal part of drawings>

10, 100: liquid crystal display device 12, 112: liquid crystal display panel

14, 114: backlight unit 16, 116: mold frame

20, 120: Light guide plate 22, 122: Reflector plate

24, 124: optical sheet 26, 126: bottom chassis

28, 128: top chassis 148: reflective unit

The present invention relates to a backlight unit, and more particularly, to a backlight unit and a liquid crystal display device for preventing the loss of light emitted from the LED device.

Among various flat panel display devices, liquid crystal displays are thinner and lighter than other display devices, have low power consumption and low driving voltage, and are widely used in various electronic devices because they can display images close to cathode ray tubes. have.

In general, a cold cathode fluorescent lamp (CCFL) is used as a backlight unit light source of the liquid crystal display. However, nowadays, researches are being actively conducted to use LEDs having advantages of high lifespan, low power consumption, light weight, and thickness as a light source.

In particular, in order to reduce weight and thickness, an LED unit having an LED element mounted on a flexible printed circuit board is used as a light source of a backlight unit.

1 is a cross-sectional view showing a conventional liquid crystal display device.

Referring to the drawings, the liquid crystal display device 10 includes a liquid crystal display panel 12 and a backlight unit 14 disposed on a rear surface of the liquid crystal display panel 12 to emit light over the entire surface of the liquid crystal display panel 12. And a mold frame 16 having a rectangular frame shape for accommodating the liquid crystal display panel 12 and the backlight unit 14, and the liquid crystal display panel 12, the backlight unit 14, and the mold frame 16. It consists of a top chassis 28 and a bottom chassis 26 for supporting.

In addition, the backlight unit 14 may be configured to reflect the light emitted from the LED unit 18 used as a light source, a light guide plate 20 for guiding light, and a light guide plate 20 positioned below the light guide plate 20. It consists of a reflecting plate 22 and a plurality of optical sheets 24 provided on the upper surface of the light guide plate 20 to diffuse and collect light transmitted from the light guide plate 20.

The LED unit 18 uses an LED element 18a that emits side light, and includes a substrate 18b on which the LED element 18a is mounted.

However, the LED element 18a has a structure that emits light at about 105 degrees to the front. Therefore, since the LED device 18a emits light not only to the front surface but also to the upper part of the light guide plate 20, there is no way to compensate for the light that does not reach the light guide plate 20, resulting in light loss. That is, there is a problem that light leakage occurs.

In order to solve the above problems, an object of the present invention is to provide a liquid crystal display device for preventing light loss by installing a separate reflection unit on the outside of the LED device.

In order to achieve the above object, the backlight unit of the present invention comprises a light guide plate and a light emitting diode provided on one side of the light guide plate, and at least one side except the light emitting portion of the light emitting diode comprises a reflective unit formed with irregularities do.

It is preferable that the reflection unit in which the unevenness is formed is formed on the light emitting diode and is a silver sheet. The unevenness is characterized in that the embossed, acid-shaped.

A liquid crystal display device using a backlight unit according to the present invention includes a liquid crystal display panel, a backlight unit including a light guide plate and a light emitting diode disposed under the liquid crystal display panel, a portion of an end side of the light guide plate, and a light emitting diode. It includes a mold frame formed with a storage space for, and at least one side except the light emitting portion of the light emitting diode is configured to include a reflective unit is formed with irregularities.

The uneven reflection unit is formed on the light emitting diode, it is preferable to form a silver sheet, a high reflection coating film. In addition, the reflective unit having the unevenness is formed in the mold frame surrounding the light emitting diode, the unevenness is characterized in that the embossed, acid-shaped.

Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to the embodiments disclosed below, but is embodied 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 numbers refer to like elements in the figures.

2 is an exploded perspective view illustrating a liquid crystal display according to the present invention, and FIG. 3 is a cross-sectional view taken along line A-A of the liquid crystal display according to the present invention.

Referring to the drawings, the liquid crystal display device 100 includes a liquid crystal display panel 112, a backlight unit 114, a mold frame 116 for accommodating the liquid crystal display panel 112 and the backlight unit 114. The liquid crystal display panel 112 includes a top chassis 128 and a bottom chassis 126 surrounding the liquid crystal display panel 112, the backlight unit 112, and the mold frame 116.

The liquid crystal display panel 112 includes a thin film transistor substrate 132, a data side and gate side tape carrier package (TCP) 134 and 136 connected to the thin film transistor substrate 132, and a data side and a gate. Data side and gate side printed circuit boards 138 and 140 respectively connected to the side tape carrier packages 134 and 136, the color filter substrate 142 corresponding to the thin film transistor substrate 132, and the thin film transistor substrate 132. ) And the color filter substrate 142 (not shown). In addition, the display device may further include a polarizer (not shown) formed to correspond to the upper portion of the color filter substrate 142 and the lower portion of the thin film transistor substrate 132.

Here, the color filter substrate 142 is a substrate in which RGB 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 142. have.

The thin film transistor substrate 132 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.

That is, as described above, when power is applied to the gate terminal and the source terminal of the thin film transistor substrate 132 and the thin film transistor is turned on, an electric field is formed between the pixel electrode and the common electrode of the color filter substrate 142. Due to this electric field, the arrangement of the liquid crystal injected between the thin film transistor substrate 132 and the color filter substrate 142 is changed, and the light transmittance is changed according to the changed arrangement to obtain a desired image.

The data side and gate side tape carrier packages 134 and 136 are respectively connected to data lines and gate lines of the thin film transistor substrate 132 to apply a data driving signal and a gate driving signal to the thin film transistors. In this case, an integrated circuit (IC) may be mounted in the data side and gate side tape carrier packages 134 and 136. The data side and gate side printed circuit boards 138 and 140 are connected to the data side and gate side tape carrier packages 134 and 136 to apply external image signals and gate drive signals.

The backlight unit 114 includes a light guide plate 120, an LED unit 118 disposed on a side surface of the light guide plate 120, a reflective plate 122 disposed below the light guide plate 120, and an upper portion of the light guide plate 120. It consists of the some optical sheet 124 provided and the reflection unit 148 formed in the upper surface of the LED unit 118.

The light guide plate 120 converts a point light source from the LED unit 118 into a surface light source, and is made of a transparent material having a constant refractive index, such as polyolefin or polycarbonate, which is usually an acrylic resin, PMMA (Poly Methy Methacrylate).

The LED unit 118 is installed at the side surface of the light guide plate 120. At this time, the light emitted from the LED unit 118 is incident to the side of the light guide plate 120, and is emitted upward through the light guide plate 120.

The LED unit 118 includes an LED element 118a and a substrate 118b on which the LED element 118a is mounted. The LED element 118a is a side view type element and emits light at about 105 degrees toward the side surface of the light guide plate 120. The substrate 118b is a flexible printed circuit board having excellent bending, and a circuit (not shown) is formed therein, and supplies external power to the LED element 118a through the circuit. The LED unit 118 is bonded by the lower side of the light guide plate 120 and the double-sided tape 130.

The reflection plate 122 is installed below the light guide plate 120 and reflects light incident from the LED unit 118 as a light source to the light exit surface of the backlight unit 114 to increase light efficiency. In addition, the reflection amount of the entire incident light is adjusted so that the entire light exit surface of the backlight unit 114 has a uniform luminance distribution. The reflective plate 122 is usually a polyester film, and the reflective film and the packing layer are coated on both sides of the polyester film to prevent incident light from leaking out and to improve the luminance characteristics with a high reflective layer structure having excellent hiding properties.

The optical sheet 124 is disposed above the light guide plate 120 to uniform the luminance distribution of the light emitted from the light guide plate 120. The optical sheet 124 is composed of one diffuser plate and a plurality of prism sheets.

The diffusion plate directs the light incident from the LED unit 118 toward the front of the liquid crystal display panel 112 and diffuses the light to have a uniform distribution in a wide range so that the liquid crystal display panel 112 is irradiated. As such a diffusion plate, it is preferable to use a film composed of a transparent resin coated with a predetermined light diffusion member on both surfaces.

The prism sheet serves to change the light incident at an oblique angle among the light incident on the prism sheet to be emitted vertically. This serves to change the light incident on the liquid crystal display panel 112 to be emitted vertically.

The mold frame 116 is formed in a rectangular frame shape, and a first accommodating space is provided on the upper surface of the mold frame 116 so that the liquid crystal display panel 112 is seated, and the liquid crystal display panel 112 is stably stored. The seating portion may be further included as possible. In addition, the lower surface of the mold frame 116 is provided with a second storage space that can accommodate the backlight unit 114 is seated on the upper surface of the bottom chassis 126 formed to surround the mold frame 116.

The bottom chassis 126 is formed in the shape of a rectangular box having an open top surface to serve to surround and protect the lower portion of the LED unit 118 and the light guide plate 120 therein. In addition, the top chassis 128 has a shape of a rectangular parallelepiped having upper and lower portions thereof, and a storage space is formed under the top chassis 128 to protect and support the upper one side of the liquid crystal display panel 112 and the mold frame 116. Is coupled to the chassis 126.

The reflective unit 148 is formed on the upper portion of the LED element 118a, and the reflective unit 148 is formed on the first surface 144 that is a surface facing the LED element 118a under the mold frame 116. It is desirable to be. Thus, the reflective unit 148 is shaped to cover one end portion of the LED element 118a and the light guide plate 120.

The reflective unit 148 may be formed of a silver sheet, and the reflective unit 148 may have a high reflectivity coating film such as ABS (Alkyl Benzene Sulfonate), PET (Polyethylen Terephthalate), or PVC (Poly Vinyl Chloride). It can be formed as. In addition, the reflective unit 148 may be formed by applying a reflective material such as silver to the first surface 144 of the mold frame 116. Therefore, it is possible to reflect light emitted upward from the LED element 118a to prevent light leakage.

As such, when the reflective unit 148 of the silver sheet is installed on the upper portion of the LED element 118a, the light efficiency is measured to be about 270 nit, and the light efficiency is improved by about 60 nit compared to the 210 nit measured in the conventional structure.

In addition, the reflective unit 148 may extend from the first surface 144 to extend to the side of the optical sheet 124. Accordingly, light leaking from the gap between the first surface 144 of the mold frame 116 and the optical sheet 124 may be prevented from the light guide plate 120, thereby improving light efficiency.

The reflective unit 148 may be further formed on the second surface 146, which is a lower sidewall of the mold frame 116. This has the effect of increasing the light efficiency by re-reflecting the light reflected from the side of the light guide plate 120 again.

In addition, the reflective unit 148 may be provided by extending from the opposite surface of the first surface to the side of the reflecting plate 122 together with the first and second surfaces 144 and 146 of the mold frame 116. That is, by installing a reflecting unit under the LED element 118a, light leakage of the gap between the light guide plate 120 and the optical sheet 124 and the gap between the light guide plate 120 and the reflector plate 122 can be prevented. Therefore, the light efficiency can be further increased.

In addition, the reflective unit 148 may be formed in a “c” shape using a reflective sheet such as silver, and may be fixed to the upper and lower surfaces of the light guide plate 116 to prevent light leakage.

4 to 6 are cross-sectional views illustrating a liquid crystal display according to another exemplary embodiment of the present invention.

This embodiment has the same structure except for the configuration method of the reflection unit 148 with the liquid crystal display device 100 shown in FIG.

Referring to the drawings, the liquid crystal display device 100 is a liquid crystal display panel 112 for outputting an image, and is installed on the rear of the liquid crystal display panel 112 to emit light over the entire surface of the liquid crystal display panel 112 The backlight unit 114, the mold frame 116 for accommodating the liquid crystal display panel 112 and the backlight unit 114, and the liquid crystal display panel 112, the backlight unit 114, and the mold frame 116. It consists of a top chassis 128 and a bottom chassis 126 for holding and fixing the same.

The backlight unit 114 includes an LED unit 118 including an LED element 118a for emitting light, a reflector 122 for reflecting light emitted from the LED unit 118, and a light guide plate for guiding light. 120, a plurality of optical sheets 124 installed on an upper surface of the light guide plate 120 to diffuse and collect light transmitted from the light guide plate 120, and a reflective unit formed on an upper surface of the LED unit 118. It consists of 148.

The mold frame 116 is provided with an accommodating space so that the reflecting plate 122, the light guide plate 120, the optical sheet 124, and the LED unit 118 are accommodated. The LCD device further includes a liquid crystal display panel 112, a backlight unit 114, and a top chassis 128 and a bottom chassis 126 that surround the outside of the mold frame 116.

Various irregularities may be formed in the reflective unit 148. In other words. The concave portion and the convex portion are formed in a predetermined pattern on the reflective unit 148 on the LED element 118a. Although the pattern is formed on the entire first surface 144 of the mold frame 116 in the drawing, it is possible to form a pattern only on the LED element 118a, which means that the LED element 118a has a straightness to the upper surface. This is to reflect the light at a predetermined angle.

5 and 6, the loss of light having straightness from the LED element 118a may be reduced by embossing or forming an acid in the reflective unit 148 on the LED element 118a.

Although the pattern is formed on the reflective unit 148 on the upper part of the LED element 118a in the drawing, various patterns may be given to three surfaces except for the light emitting surface of the LED element.

That is, a pattern may be formed on the first surface 144, the second surface 146, and the opposite surface of the first surface 144 of the mold frame 116, and as shown in FIGS. 4 to 6. And the concave portion, the embossing and the acid forming may be formed in combination with each other.

In this way, by providing the reflection unit 148 on the outer side of the LED element 118a, not only light leakage but also a pattern on the reflection unit 148 further improves the light efficiency.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and various changes and modifications can be made by those skilled in the art within the scope of the claims. It is self-evident.

As described above, the liquid crystal display device according to the present invention forms a reflection unit around the LED element. Therefore, the present invention has the effect of preventing light loss and increasing light efficiency.

In addition, the present invention has the effect of further increasing the light efficiency by forming a variety of irregularities in the reflection unit.

Claims (9)

The light guide plate, It includes a light emitting diode installed on one side of the light guide plate, At least one side of the light emitting diode of the light emitting unit is a backlight unit, characterized in that the reflective unit is formed with irregularities. The backlight unit of claim 1, wherein the reflective unit having the unevenness is formed on the light emitting diode. The backlight unit according to claim 1 or 2, wherein the reflective unit on which the unevenness is formed is a silver sheet. The backlight unit according to claim 1 or 2, wherein the irregularities are embossed and acid shaped. A liquid crystal display panel, A backlight unit including a light guide plate and a light emitting diode disposed under the liquid crystal display panel; A mold frame including a portion of an end side of the light guide plate and an accommodation space for accommodating the light emitting diode; And a reflective unit having irregularities formed on at least one side of the light emitting diode. The liquid crystal display device according to claim 5, wherein the reflective unit having the unevenness is formed on the light emitting diode. The liquid crystal display device according to claim 5 or 6, wherein the reflection unit having the unevenness is a silver sheet or a high reflection coating film. The liquid crystal display device according to claim 5 or 6, wherein the reflective unit having the unevenness is formed in a mold frame surrounding the light emitting diode. 7. The liquid crystal display device according to claim 5 or 6, wherein the irregularities are embossed and acid shaped.

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