KR20110056015A - Back light unit and liquid crystal display device using the same - Google Patents

Abstract

PURPOSE: A backlight unit and liquid crystal display device using the same are provided to enhance the light leakage which is generated through an incident surface and to increase the quality of product by preventing light leakage. CONSTITUTION: A plurality of lamps(40) generates light. A lamp holder(41) mounts a plurality of lamps and is fixedly arranged in the inside wall of a bottom cover. A diffusing plate(70) receives the light from the lamps. A plurality of optical sheets(80) is arranged on the diffusing plate and radiates the light from the diffusing plate. A plurality of fixing units blocks the light on the optical sheet in order to fix the optical sheet on a bottom cover.

Description

BACK LIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit. In particular, a backlight unit capable of improving light leakage characteristics generated through the incident surfaces of optical sheets by improving light incident surface structures of optical sheets to which light is incident and a liquid crystal display using the same It is about.

As the information society develops, the demand for image display devices is increasing in various forms. Recently, liquid crystal displays, field emission displays, plasma display panels, Various flat panel displays, such as a light emitting display, are utilized.

Among such flat panel displays, liquid crystal displays are widely used due to their low power drive and excellent image quality. As the liquid crystal display, a liquid crystal panel including two substrates facing each other and liquid crystal interposed between the two substrates is used. Here, the liquid crystal panel displays an image by changing the liquid crystal array by the electric field generated between the two substrates. However, since the liquid crystal panel corresponds to a non-light emitting display panel, the liquid crystal panel receives light from a backlight unit to display an image.

In general, the backlight unit is divided into an edge type backlight unit and a direct type backlight unit according to the position of the lamp. Here, the edge type backlight unit is mainly used in a small liquid crystal display such as a notebook, and the direct type backlight unit is mainly used in a medium and large liquid crystal display such as a television.

Recently, in accordance with the trend of miniaturization, thinning, and lightening of the backlight unit, a backlight unit using a light emitting diode (Light Emitting Diode), which is advantageous in terms of power consumption, weight, and brightness, has been developed instead of a fluorescent lamp. In particular, in order to implement a lightweight thin high brightness backlight unit, an edge type backlight unit using a light emitting diode for supplying light from a lower side of the backlight unit is mainly developed.

However, in the conventional edge type backlight unit, components such as a plurality of light emitting diodes, a diffusion plate for changing the direction of light propagation, and a plurality of optical sheets for improving light diffusion efficiency are stacked and assembled in a case. There existed a problem that light leakage generate | occur | produced by the assembly structure. In other words, in the case of the edge type backlight unit, since the light generated through the light emitting diode is incident on the side incident surface of the diffusion plate and the optical sheets after being emitted to the front part of the diffusion plate and the optical sheets, Light leakage occurs prominently at the incident surface. As such, when light leakage occurs remarkably, defects such as a bright line phenomenon occur and the quality thereof is deteriorated.

The present invention is to solve the above problems, the backlight unit that can improve the light leakage characteristics generated through the light incident surface by improving the light incident surface structure of the light incident light sheet and the liquid crystal display device using the same The purpose is to provide.

A backlight unit according to an embodiment of the present invention for achieving the above object comprises a plurality of lamps for generating light; A lamp fixing part for mounting the plurality of lamps and fixedly disposed on an inner side surface of a bottom cover; A diffuser plate which receives light from each of the lamps on the side incident surface thereof and changes the traveling direction of the light toward the front surface to emit the light; And a plurality of optical sheets disposed on the diffuser plate to vertically emit light from the diffuser plate and the side light incident surface thereof, wherein any one of the optical sheets disposed at the front of the plurality of optical sheets has the bottom A plurality of fixing parts protruding to be fixed to the cover is provided, and each of the fixing parts is provided with a light blocking film for blocking light.

The plurality of fixing parts may be configured at positions corresponding to the plurality of fixing pins provided on the bottom cover, respectively, and each of the fixing parts may include at least one opening to be fixed to each of the fixing pins.

The light blocking layer may be formed of a light absorbing material or a light absorbing tape or a light absorbing film, and may be formed on all or part surfaces of the fixing part except for the openings provided in the fixing parts.

The light blocking layer may be configured only on at least one fixing unit positioned in a direction adjacent to each of the plurality of fixing units.

At least one optical sheet size of the remaining optical sheets other than the optical sheet positioned at the front of the plurality of optical sheets sequentially disposed on the front surface of the diffuser plate may be smaller than the size of the diffuser plate. .

The distance between the side incident surface of each optical sheet formed in a smaller size than the diffuser plate and the respective lamps is longer than the distance between the side incident surface of the diffuser plate and the respective lamps.

The plurality of fixing pins provided on the bottom cover are configured to protrude on the front of the seating portion of the bottom cover, so that the optical sheet on the front surface may be fixed by combining the openings of the fixing pins and the fixing portions. It is characterized by one.

The plurality of fixing pins provided on the bottom cover are configured to protrude to the rear surface of the seating portion of the bottom cover, and the optical sheet, that is, the polarizing sheet of the front surface, is bottomed by combining the fixing pins and the openings of the fixing portions. Characterized in that it can be fixed on the back of the seating portion of the cover.

The size of the plurality of optical sheets sequentially seated on the front surface of the diffuser plate is formed smaller than the size of the diffuser plate, so that the side light incident surface of each optical sheet formed to a smaller size than the diffuser plate and the respective lamps. The distance is characterized in that it is configured longer than the distance between the side incident surface of the diffusion plate and each lamp.

In addition, the liquid crystal display device using the backlight unit according to an embodiment of the present invention for achieving the above object is provided with a plurality of pixel areas and a backlight for irradiating light to the liquid crystal panel for displaying an image In the liquid crystal display device provided with a unit, the backlight unit for irradiating light to the liquid crystal panel is characterized by including at least one of the features of the above-described backlight unit.

The backlight unit and the liquid crystal display using the same according to an exemplary embodiment of the present invention having the above characteristics may improve light leakage characteristics generated through the light incident surface by improving the light incident surface structure of the optical sheets to which light is incident. have. In addition, it is possible to further improve the quality of the product by preventing defects such as the bright line due to the light leakage characteristics.

Hereinafter, a backlight unit and a liquid crystal display using the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view schematically illustrating a backlight unit and a liquid crystal display using the same according to an exemplary embodiment of the present invention.

The backlight unit and the liquid crystal display using the same according to the embodiment of the present invention shown in FIG. 1 include a backlight unit 2; Panel guide 90; The liquid crystal panel 100 and the case 130 are provided.

The liquid crystal panel 100 is stacked on the panel support of the panel guide 90 to adjust the transmittance of light from the backlight unit 2 to display an image. To this end, the liquid crystal panel 100 is a liquid crystal (not shown) formed between the lower substrate 102 and the upper substrate 104, the lower substrate 102 and the upper substrate 104, the lower substrate 102 and the upper substrate ( And a spacer (not shown) for maintaining a constant gap therebetween.

The upper substrate 104 may include a color filter; Black matrix; And a common electrode.

The lower substrate 102 includes a thin film transistor formed in each cell region defined by data lines and gate lines and a pixel electrode connected to the thin film transistor. The thin film transistor switches the image signal supplied from the data line to the pixel electrode in response to the gate-on voltage supplied from the gate line. Here, the common electrode formed on the upper substrate 104 may be formed on the lower substrate 102 according to the liquid crystal mode.

In addition, a non-display area of the lower substrate 102 is provided with a data pad area connected to each of the data lines and a gate pad area connected to each of the gate lines.

A plurality of data circuit films 110 mounted with data integrated circuits 112 for supplying image signals to data lines are attached to the data pad region. Each data circuit film 110 may be a tape carrier package or a chip on film. Each of the data circuit films 110 supplies a data signal from a data printed circuit board (not shown) to the data integrated circuit 112, and supplies an image signal output from the data integrated circuit 112 to each data line. do. The data integrated circuit 112 may be mounted on the lower substrate 102 by a chip on glass method.

A plurality of gate circuit films 120 on which the gate integrated circuit 122 is mounted to supply gate-on voltages to the gate lines are attached to the gate pad region. Each gate circuit film 120 may be a tape carrier package or a chip on film. Each of the gate circuit films 120 supplies a gate control signal supplied from the data printed circuit board to the gate integrated circuit 122 through the data circuit film 110 and the lower substrate 102, and the gate integrated circuit 122. The gate-on voltage outputted from the N / A) is supplied to each gate line. Here, the gate integrated circuit 122 may be mounted on the lower substrate 102 by a chip on glass method, or may be formed on the lower substrate 102 together with the manufacturing process of the thin film transistor.

The panel guide 90 is mounted to the seating portion of the bottom cover 10 to wrap the edges and side surfaces of the diffusion plate 70 and the plurality of optical sheets 80 and surround the side surfaces of the bottom cover 10. The panel guide 90 includes a panel supporter for supporting the liquid crystal panel 100. The panel support part is formed to be stepped to support the rear non-display area and the side surface of the liquid crystal panel 100.

The case 130 is bent to surround the front non-display area of the liquid crystal panel 100 and the side surface of the bottom cover 10. At this time, the case 130 is fastened and fixed to the panel guide 90 surrounding the side of the bottom cover 10.

The backlight unit 2 includes a plurality of lamps 40 for generating light; A lamp fixing part (41) for mounting the plurality of lamps (40) and fixedly disposed on an inner side surface of the bottom cover (10); A diffuser plate 70 which receives light from each of the lamps 40 to the side incident surface thereof and changes the traveling direction of the light toward the front surface thereof to emit light; A plurality of optical sheets 80 disposed on the diffusion plate 70 for vertically emitting light from the diffusion plate 70 and the light incident surface thereof are provided. Here, any one optical sheet disposed on the front of the plurality of optical sheets 80 is provided with a plurality of fixing parts protruding to be fixed to the bottom cover 10, the front of the fixing portion to block the light A light shielding film is formed.

Each of the plurality of lamps 40 is detachably mounted to the lamp fixing part 41 so as to face the side incident surface of the diffuser plate 70 and the side incident surface of at least one of the plurality of optical sheets 80. do. Here, a light emitting diode 40 may be used as the plurality of lamps 40. Meanwhile, each lamp 40 may be an external electrode fluorescent lamp (EEFL), a hot cathode fluorescent lamp (HCFL) or a cold cathode fluorescent lamp (CCFL) may be used. In the present invention, an example in which the light emitting diode is applied will be described in more detail.

Such a plurality of lamps 40 are turned on by the lamp driving power supplied from each lamp fixing part 41 to irradiate light to the light entering surface of the diffusion plate 70 and each optical sheet 80.

The bottom cover 10 is configured to accommodate and fix the diffuser plate 70 and each optical sheet 80 while the lamps 40 are arranged while the bottom surface facing the liquid crystal panel 100 or the optical sheet 80 is arranged. And a seating portion extending from the inner side so as to face the formed inner side, the bottom surface of the lower portion. Reflective sheets (not shown) are further formed on the lower bottom surface and the inner side surface of the bottom cover 10 to reflect light from each lamp 40 toward the liquid crystal panel 100, that is, the front surface thereof. As such, the bottom cover 10 has a rectangular frame shape as shown in FIG. 1. On the other hand, the front seating portion of the bottom cover 10 may be further provided with a fixing pin for fixing at least one of the optical sheet of the above optical sheet (80). The fixing structure of the fixing pin and the optical sheet will be described in detail with reference to the accompanying drawings.

The lamp fixing part 41 is provided with the plurality of lamps 40 on one side of the bottom cover 10 to supply lamp driving power transmitted from the outside to the plurality of lamps 40.

The diffusion plate 70 is stacked on the front opening, that is, the inner bottom surface of the bottom cover 10 having a rectangular frame shape. The diffusion plate 70 converts the propagation path of the light irradiated to the side incident surface and diffuses it to the entire area of the liquid crystal panel 100.

The plurality of optical sheets 80 adjusts the light path so that the incident light diffused through the diffusion plate 70 is irradiated perpendicularly to the liquid crystal panel 100. To this end, the plurality of optical sheets 80 may include at least one prism sheet 82, a diffusion sheet 84, a polarizing sheet 84, and a protective sheet (not shown) for condensing light diffused by the diffusion plate 70. ), Etc.

In addition, the backlight unit 2 further includes a lamp driving circuit unit (not shown) for generating lamp driving power to drive the respective lamps 40 so that each lamp 40 is connected to the lamp 40 through the lamp fixing unit 41. Supply the driving power. Here, the lamp driving circuit unit is composed of at least one inverter or switching circuits to convert the external power input to the AC power to the DC power to generate the lamp driving power. The generated lamp driving power is supplied to the respective lamps 40 according to the driving timing of the liquid crystal panel 100 or the like.

As described above, the backlight unit 2 generates light by illuminating the plurality of lamps 40 with the lamp driving power supplied from the lamp driving circuit unit to irradiate the liquid crystal panel 100 or the like.

As described above, the backlight unit 2 is provided with a plurality of optical sheets 80 to irradiate the light incident from the diffuser plate 70 or the lamp 40 vertically to the front thereof. That is, the plurality of optical sheets 80 adjusts the light path so that light is emitted vertically. For this purpose, the optical sheets 80 may include at least one prism sheet 82, a diffusion sheet 84, and a polarizing sheet 84. ) And a protective sheet, etc. are sequentially stacked. In this case, the types of stacked sheets or the stacking order may be converted according to the use purpose of the backlight unit 10.

Each optical sheet 80, that is, at least one prism sheet 82, the diffusion sheet 84, the polarizing sheet 84, and the protective sheets are sequentially stacked and seated on the front surface of the diffusion plate 70. One of the optical sheets disposed at the front of the plurality of optical sheets 80 is provided with a plurality of fixing parts protruding to be fixed to the front of the bottom cover 10, the front of the fixing portion to block the light A blocking film is formed.

FIG. 2 is a diagram illustrating an optical sheet of any one of the plurality of optical sheets illustrated in FIG. 1.

As illustrated in FIG. 2, any one of the optical sheets disposed at the front of the plurality of optical sheets, for example, each side of the polarizing sheet 86 may be fixed to the front of the bottom cover 10. A plurality of protruding fixing parts 86b are provided, and a light blocking film 86a for blocking light is formed on the front of the fixing parts 86b. Hereinafter, only the case in which the polarizing sheet 86 is disposed at the front of the plurality of optical sheets 80 will be described.

The plurality of fixing parts 86b provided in the polarizing sheet 86 are respectively configured at positions corresponding to the plurality of fixing pins provided in the bottom cover 10, and each of the fixing parts 86b includes the bottom cover 10. At least one opening is formed to be fixed to the fixing pin. Therefore, each fixing part 86b of the polarizing sheet 86 is assembled so that the opening is fitted to the fixing pin of the bottom cover 10, and the at least one prism sheet 82 provided in the polarizing sheet 86 and the lower part thereof. Or both of the diffusion sheets 84 are fixed.

Meanwhile, at least one fixing portion 86b of the plurality of fixing portions 86b is further provided with a light blocking film 86a for blocking light incident from the rear surface, and the light blocking film 86a is coated with a light absorbing material. Or a light absorbing tape, a light absorbing film, or the like, and is formed on all or part surfaces of the fixing portion 86b except for the opening provided in the fixing portion 86b.

Meanwhile, in FIG. 2, the light blocking film 86a may be formed in each of the fixing parts 86b. However, the light blocking film 86a may include the respective lamps 40 of the plurality of fixing parts 86b. It may be configured only in the at least one fixing portion (86b) located in the direction adjacent to the.

3 is a cross-sectional view illustrating an assembly configuration of the backlight unit illustrated in FIG. 1.

As shown in FIG. 3, a plurality of lamps 40 are disposed on an inner side surface of the bottom cover 10, and light from the plurality of lamps 40 is formed on a lower surface of the bottom cover 10. The diffusion plate 70 is seated to be applied to the light surface.

In addition, a plurality of optical sheets 80 are sequentially seated on the front surface of the diffusion plate 70, which are positioned at the most front of the plurality of optical sheets 80 sequentially seated on the front surface of the diffusion plate 70. The optical sheet size of at least one of the remaining optical sheets other than the optical sheet is smaller than the size of the diffusion plate 70. Therefore, the distance between the side light incident surface of each optical sheet formed in a smaller size than the diffuser plate 70 and the respective lamps 40 is smaller than the distance between the side light incident surface of the diffuser plate 70 and the respective lamps 40. It is constructed longer. In the case of FIG. 3, the distance between the side incident surfaces of each optical sheet 82 and 84 formed in a smaller size than the diffuser plate 70 and the respective lamps 40 is the side incident surface of the diffuser plate 70 and the respective lamps. An example may be configured that is longer than the distance between the 40 parts by x lengths.

4 is a configuration diagram illustrating a coupling state of the bottom cover and the polarizing sheet fixing unit illustrated in FIG. 3.

Referring to FIGS. 3 and 4, the plurality of fixing pins 10a provided on the bottom cover 10 are configured to protrude in front of the seating portion 10b of the bottom cover 10, and the fixing pins 10a may be formed. The opening of the fixing portions 86b and the polarizing sheet 86 may be fixed to the frontmost optical sheet.

As described above, in the present invention, the distance between the side incident surfaces of each optical sheet 82 and 84 formed in a smaller size than the diffuser plate 70 and the respective lamps 40 is the side incident surface of the diffuser plate 70. By making it longer than the distance between the lamps 40 and each of the lamps 40 it is possible to primarily prevent the side light incident path of the optical sheet (82, 84) to prevent light leakage through the light incident surface. As shown in FIG. 4, the light blocking film 86a is further formed on each of the plurality of fixing portions 86b of the optical sheet 86 positioned at the foremost front among the optical sheets 80, respectively. Light leakage through the fixing portion 86b can be prevented.

5 is another cross-sectional view illustrating an assembly configuration of the backlight unit illustrated in FIG. 1.

As shown in FIG. 5, a plurality of lamps 40 are disposed on an inner side surface of the bottom cover 10, and light from the plurality of lamps 40 is formed on a lower surface of the bottom cover 10. The diffusion plate 70 is seated to be applied to the light surface.

As shown in FIG. 5, the plurality of fixing pins 10a provided on the bottom cover 10 are configured to protrude on the rear surface of the seating portion 10b of the bottom cover 10, and each of the fixing pins 10a is provided. ) And the openings of the respective fixing parts 86b allow the frontmost optical sheet, that is, the polarizing sheet 86, to be fixed at the rear of the seating part of the bottom cover 10.

In this case, as in FIG. 3, the sizes of the plurality of optical sheets 80 sequentially seated on the front surface of the diffusion plate 70 are smaller than the size of the diffusion plate 70. Therefore, the distance between the side light incident surface of each optical sheet formed in a smaller size than the diffuser plate 70 and the respective lamps 40 is smaller than the distance between the side light incident surface of the diffuser plate 70 and the respective lamps 40. It is constructed longer. In the case of FIG. 5, the distance between the side incident surface of each optical sheet 80 and the respective lamps 40 formed in a smaller size than that of the diffuser plate 70 is the side incident surface of the diffuser plate 70 and the respective lamps 40. One example is configured to be longer by x length than the distance between them.

As described above, in the present invention, the distance between the side light incident surfaces of the respective optical sheets 82 and 84 formed in a smaller size than the diffuser plate 70 and the respective lamps 40 is the side of the diffuser plate 70. By making the light incident surface longer than the distance between the lamps 40, the light incident paths of the optical sheets 82 and 84 may be converted to prevent light leakage through the light incident surfaces. In addition, a light blocking film 86a is further formed in each of the plurality of fixing portions 86b of the optical sheet 86 positioned at the front of each of the optical sheets 80, thereby providing light leakage through each of the fixing portions 86b. It can prevent.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention It will be apparent to those skilled in the art.

1 is an exploded perspective view schematically illustrating a backlight unit and a liquid crystal display using the same according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating an optical sheet of any one of the plurality of optical sheets illustrated in FIG. 1.

3 is a cross-sectional view illustrating an assembly configuration of the backlight unit illustrated in FIG. 1.

4 is a configuration diagram showing a coupling state of the bottom cover and the polarizing sheet fixing unit shown in FIG.

FIG. 5 is a cross-sectional view illustrating another configuration of the backlight unit of FIG. 1.

* Brief description of symbols for the main parts of the drawings.

2: back light unit 10: bottom cover

80: plurality of optical sheets 70: diffuser plate

90 panel guide 100 liquid crystal panel

130: case

Claims (10)

A plurality of lamps for generating light; A lamp fixing part for mounting the plurality of lamps and fixedly disposed on an inner side surface of a bottom cover; A diffuser plate which receives light from each of the lamps on the side incident surface thereof and changes the traveling direction of the light toward the front surface to emit the light; A plurality of optical sheets disposed on the diffuser plate to vertically emit light from the diffuser plate and side light incident surfaces thereof; At least one optical sheet disposed at the front of the plurality of optical sheets is provided with a plurality of fixing parts protruding to be fixed to the bottom cover, and a light blocking film for blocking light is formed on the front of each fixing part. Backlight unit to say. The method of claim 1, The plurality of fixing parts And a plurality of fixing pins provided in the bottom cover, respectively, at positions corresponding to the fixing pins, wherein each of the fixing parts includes at least one opening to be fixed to each of the fixing pins. The method of claim 2, The light blocking film is A back light unit coated with a light absorbing material or made of a light absorbing tape or a light absorbing film and formed on all or part surfaces of the fixing part except for the openings provided in the fixing parts. The method of claim 3, wherein The light blocking film is And at least one fixing part positioned in a direction adjacent to the respective lamps among the plurality of fixing parts. The method of claim 4, wherein Of the plurality of optical sheets sequentially disposed on the front of the diffusion plate Backlight unit, characterized in that the optical sheet size of at least one of the remaining optical sheets other than the optical sheet located in the front is smaller than the size of the diffusion plate. The method of claim 5, And a distance between the side incident surface of each optical sheet formed in a smaller size than the diffuser plate and the respective lamps is longer than the distance between the side incident surface of the diffuser plate and the respective lamps. The method of claim 6, A plurality of fixing pins provided on the bottom cover The back cover unit is configured to protrude on the front of the seating portion of the bottom cover, so that the optical sheet of the front surface is fixed by the combination of the opening of each of the fixing pins and the respective fixing portion. The method of claim 6, A plurality of fixing pins provided on the bottom cover It is configured to protrude on the bottom of the bottom portion of the bottom cover, so that the optical sheet of the front surface, that is, the polarizing sheet can be fixed on the bottom of the bottom portion of the bottom cover by engaging the opening of each fixing pin and the fixing portion. Back light unit, characterized in that. The method of claim 4, wherein The size of the plurality of optical sheets sequentially seated on the front of the diffusion plate The distance between the side incident surface of each optical sheet and the respective lamps formed smaller than the size of the diffuser plate and smaller than the diffuser plate is longer than the distance between the side incident surface of the diffuser plate and the respective lamps. Back light unit, characterized in that configured. In a liquid crystal display device comprising a liquid crystal panel having a plurality of pixel areas to display an image and a backlight unit for irradiating light to the liquid crystal panel, A backlight unit for irradiating light to the liquid crystal panel includes a feature of at least one of the preceding claims.

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