KR20080076445A - Backlight unit and lc display device - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) having the same are provided to prevent the movement of optical sheets, thereby offering uniform display quality to the entire surface of a display panel. A backlight unit comprises a plurality of lamps(50), a diffusion plate(60) positioned above the lamps, a plurality of optical sheets(62,64) positioned on the diffusion plate, and a lower case(70) in which the lamps, the diffusion plate, and the optical sheets are placed. The diffusion plate is configured to prevent the shapes of the lamps from being displayed on a display screen of an LCD(Liquid Crystal Display) panel and provide a light having a uniform brightness distribution. A protrusion(61) is upwardly protruded from the end portion of the diffusion plate, wherein the protrusion of the diffusion plate has a bar shape. The optical sheets are disposed within the diffusion plate with the protrusion, thereby restricting the movement of the optical sheets and preventing the separation of the optical sheets.

Description

Backlight unit and liquid crystal display device having same {Backlight unit and LC display device}

1 is a block diagram showing the basic configuration of a general liquid crystal display device

2 is a block diagram showing a general liquid crystal panel and a pixel configuration

3 is a perspective view of a direct type backlight unit for a conventional liquid crystal display device;

4 is a cross-sectional view of the direct backlight unit structure of FIG. 3.

5 to 6 are partial cross-sectional views illustrating the problems caused in the direct type backlight unit according to FIG. 4, respectively.

7 is a cross-sectional view illustrating a backlight unit for a display device according to a first embodiment of the present invention.

8 is a cross-sectional view illustrating a backlight unit for a display device according to a second embodiment of the present invention.

<Brief description of the main parts of the drawing>

50: lamp 60, 80: diffusion plate

61, 81: projections 62, 64, 82, 84: optical sheet

70: 90: lower case

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a display device, and more particularly, to a backlight unit and a liquid crystal display device having the same, which can limit the movement of an optical sheet inserted into the display device to prevent display quality degradation.

Among the display devices, in particular, liquid crystal displays have advantages of small size, thinness, and low power consumption, and are used as notebook computers, office automation devices, and audio / video devices. In particular, an active matrix liquid crystal display device using a thin film transistor (hereinafter referred to as "TFT") as a switch element is suitable for displaying a dynamic image.

FIG. 1 is a block diagram illustrating a basic configuration of a general liquid crystal display device, and is largely divided into a liquid crystal panel 2 and an LCM driving circuit unit 26 having a configuration excluding the liquid crystal panel 2.

In each configuration, the interface 10 includes data (RGB Data) and control signals (input clock, horizontal synchronous signal, vertical synchronous signal, data enable signal, etc.) input from the drive system such as a personal computer to the LCM drive circuit. Are supplied to the timing controller 12. Mainly, LVDS (Low Voltage Differential Signal) interface and TTL interface are used for data and control signal transmission from driving system. In addition, the interface function may be collected and used together with the timing controller 12 in a single chip.

As illustrated in FIG. 2, the liquid crystal panel 2 forms a plurality of pixel regions by crossing a plurality of data lines DL1 to DLm and a plurality of gate lines GL1 to GLn on a glass substrate. In the region, a thin film transistor TFT and a liquid crystal LC are configured to display a screen.

The timing controller 12 drives the data driver 18 composed of a plurality of drive integrated circuits and the gate driver 20 composed of a plurality of gate driver integrated circuits using a control signal input through the interface 10. Generate a control signal for In addition, the data input through the interface 10 is transmitted to the data driver 18.

The reference voltage generator 16 generates reference voltages of a digital to analog converter (DAC) used in the data driver 18. Reference voltages are set by the producer based on the transmittance-voltage characteristics of the panel.

The data driver 18 selects reference voltages for analog conversion of input digital data in response to control signals input from the timing controller 12, and outputs analog video data generated by the selected reference voltage to the liquid crystal panel 2. It is supplied to the to control the rotation angle of the liquid crystal molecules.

The gate driver 20 performs on / off control of thin film transistors TFTs arranged on the liquid crystal panel 2 in response to control signals input from the timing controller 12. By sequentially enabling the gate lines GL1 to GLn by one horizontal synchronizing time, analog image signals supplied from the data driver 18 are sequentially driven by sequentially driving the thin film transistors TFT on the liquid crystal panel 2 by one line. Each pixel is applied to the pixels connected to the TFTs.

The power supply voltage generator 14 supplies operating power of each component and generates and supplies a common electrode voltage of the liquid crystal panel 2.

In the liquid crystal display device having the above configuration, a backlight unit for supplying light from the rear side is positioned. In particular, a large sized panel adopts a direct type backlight unit in which a plurality of lamps are positioned below the liquid crystal panel.

The direct type backlight unit does not need a light guide plate for converting the linear light of the lamp into the surface light, and a plurality of lamps provided on the lower side of the display surface and a reflective sheet for reflecting light emitted from the lamp to the display surface to prevent light loss. And light scattering means including a diffuser plate and a plurality of optical sheets to scatter light on top of the lamp.

3 is a perspective view of a direct type backlight unit for a conventional liquid crystal display device, a plurality of lamps 1, a lower case 3 for fixing and supporting the lamps 1, the lamps 1 and the liquid crystal panel; And a plurality of light scattering means 5a, 5b, 5c disposed between them (not shown).

The light scattering means (5a, 5b, 5c) is to prevent the shape of the lamp 1 from appearing on the display surface of the liquid crystal panel and to provide a light source having a uniform brightness distribution as a whole, to enhance the light scattering effect In order to achieve this, a diffusion plate (diffusion sheet or diffusion plate), an optical sheet, and the like are formed between the liquid crystal panel.

The inner surface of the lower case 3 is disposed with a reflector 7 so that the light emitted from the lamp 1 can be concentrated to the display of the liquid crystal panel, in order to maximize the utilization efficiency of the light.

The lamp 1 is a Cold Cathode Fluorescent Lamp (CCFL), and electrodes 9 and 9a are disposed at both ends of a tube, and emit light when power is applied to the electrode. Both ends of 1) are fitted into grooves formed on both sides of the lower case 3.

In the direct type backlight liquid crystal display device having the above structure, a plurality of lamps 1 are arranged in the same direction as the cross-sectional structure of FIG. 4, and the light emitting lamp 1 is disposed inside. A lower plate 3 mounted thereon, a diffuser plate 5a having an end coupled to the lower case 3 on an upper portion of the lamp 1, and an upper portion of the diffuser plate 5a. It consists of a plurality of optical sheets (5b, 5c).

However, in the direct type backlight liquid crystal display device having the above characteristics, when the impact is applied to the liquid crystal display device, the backlight unit is flowed, and as shown in the partial sectional view of FIG. 5, some optical sheets 5b and 5c Deviation may occur.

In addition, as shown in FIG. 6, flow between the light scattering means 5a, 5b, and 5c is generated by an external impact, so that the diffusion protrusions 6 formed on the upper surface of the diffusion plate 5a are worn out, and thus, the display panel is worn on the display panel. Problems such as the appearance of whitish phenomena appearing in comparison with the region may occur.

The present invention has been made to solve the above problems, and an object thereof is to provide an even display quality on the front of the display panel by fixing the flow between the optical sheets in the direct type backlight liquid crystal display device.

The present invention to achieve the above object, the lamp; A diffusion plate positioned above the lamp and having a protruding portion at an end thereof; An optical sheet positioned on the diffusion plate; It provides a backlight unit including a lower case for the lamp, the diffusion plate and the optical sheet.

In addition, the present invention, the liquid crystal panel; A backlight unit having a lamp, a diffuser plate positioned above the lamp and having a protruding portion at an end thereof, an optical sheet positioned above the diffuser plate, and a lower case in which the lamp, the diffuser plate, and the optical sheet are placed; It provides a liquid crystal display device comprising.

In the backlight unit and the liquid crystal display, the protrusion may have a bar shape or a "-" shape.

The backlight unit and the liquid crystal display further include a reflection plate positioned between the lamp and the lower case.

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

First embodiment

FIG. 7 is a cross-sectional view illustrating a backlight unit for a display device according to a first embodiment of the present invention, and illustrates a backlight unit configuration in a direct type backlight liquid crystal display device.

In the configuration, a plurality of lamps 50, a diffusion plate 60 positioned on the plurality of lamps 50, a plurality of optical sheets 62 and 64 positioned on the diffusion plate 60, and The lamp 50, the diffusion plate 60, and the lower case 70 having the plurality of optical sheets 62 and 64 disposed therein.

In addition, a reflector (not shown) is provided between the lamp 50 and the lower case 70, that is, the inner bottom surface of the lower case 70 so that the light emitted from the lamp 50 can be concentrated toward the diffusion plate 60. ) May be arranged.

The lamp 50 is a fluorescent lamp, preferably a cold cathode fluorescent lamp (CCFL) to the upper portion of the diffusion plate 60 and the plurality of optical sheets (62, 64) to emit light when the power is supplied. In the case of a liquid crystal display device having a liquid crystal panel (not shown), light is supplied to the liquid crystal panel side.

The diffusion plate 60 is positioned above the lamp 50 to prevent the shape of the lamp 50 from appearing on the display surface of the liquid crystal panel and to provide a light source having a uniform brightness distribution as a whole. The end portion is a bar (bar) is a structure in which a protrusion 61 is projected upwardly vertically formed. In this case, the protrusions 61 formed at the end of the diffusion plate 60 are illustrated as being configured at both ends in FIG. 7, but may be formed at one end or at all ends appearing in the planar shape of the diffusion plate 60. have.

By limiting the flow of the optical sheets 62 and 64 by placing a plurality of optical sheets 62 and 64 inside the diffuser plate 60 having the protrusions 61, the optical sheets 62 and 64 upon impact. ) Can improve the phenomenon of deviation. In addition, as the flow of the optical sheets 62 and 64 is restricted, the whitening phenomenon due to wear of the light diffusion protrusion (not shown) configured on the upper surface of the diffusion plate 60 may be improved.

Second embodiment

FIG. 8 is a cross-sectional view illustrating a backlight unit for a display device according to a second embodiment of the present invention, and shows a configuration of a backlight unit in a direct type backlight liquid crystal display device as in the first embodiment.

In the configuration, a plurality of lamps 50, a diffusion plate 80 positioned on the plurality of lamps 50, a plurality of optical sheets 82 and 84 positioned on the diffusion plate 80, and The lamp 50, the diffusion plate 80, and a plurality of optical sheets 82 and 84 are disposed in the lower case 90.

In addition, a reflector (not shown) may be disposed between the lamp 50 and the lower case 90, that is, the inner bottom surface of the lower case 90 so that the light emitted from the lamp 50 may be concentrated toward the diffusion plate 80. May be arranged.

The lamp 50 is a fluorescent lamp, preferably a cold cathode fluorescent lamp (CCFL) is the upper portion of the diffusion plate 80 and the plurality of optical sheets (82, 84) to emit light when power is supplied to the upper In the case of a liquid crystal display device having a liquid crystal panel (not shown), the light is supplied to the liquid crystal panel side.

The diffusion plate 80 is positioned above the lamp 50 to prevent the shape of the lamp 50 from appearing on the display surface of the liquid crystal panel and to provide a light source having a uniform brightness distribution as a whole. The end portion is a structure in which a protrusion 81 protruding in a "-" shape is formed.

In this case, the protrusions 81 formed at the ends of the diffusion plate 80 are shown as being configured at both ends in FIG. 8, but may be configured at one end or at all ends appearing in the planar shape of the diffusion plate 80. have.

By limiting the flow of the optical sheets 82 and 84 by placing a plurality of optical sheets 82 and 84 inside the diffuser plate 80 having the protrusions 81, and also during impact, the optical sheets 82 and 84 By fixing the end of the) it can improve the phenomenon that the optical sheets (82.84) are separated. In addition, as the flow of the optical sheets 82 and 84 is limited, the whitening phenomenon due to wear of the light diffusion protrusion (not shown) configured on the upper surface of the diffusion plate 80 may be improved.

The backlight unit and the liquid crystal display device having the same according to the present invention as described above improve the whitening phenomenon by fixing the separation of the optical sheet due to impact and the flow between the optical sheets in the direct type backlight liquid crystal display device, thereby improving the whitening phenomenon in front of the display panel. This has the effect of providing an even display quality.

Claims (6)

With a lamp; A diffusion plate positioned above the lamp and having a protruding portion at an end thereof; An optical sheet positioned on the diffusion plate; A lower case in which the lamp, the diffusion plate, and the optical sheet are placed Backlight unit comprising a The method according to claim 1, The protrusion unit has a bar shape or a “a” shape backlight unit The method according to claim 1, The backlight unit further comprises a reflector located between the lamp and the lower case. A liquid crystal panel; A backlight unit including a lamp, a diffuser plate positioned above the lamp and having a protruding portion at an end thereof, an optical sheet positioned above the diffuser plate, and a lower case to which the lamp, the diffuser plate, and the optical sheet are placed. Liquid crystal display comprising a The method according to claim 4, Liquid crystal display device characterized in that the protruding portion is a bar (bar) or "" shaped " The method according to claim 4, A liquid crystal display further comprising a reflector disposed between the lamp and the lower case.

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