KR20080062388A - Backlight unit and liquid crystal display device having the same - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) having the backlight unit are provided to reduce the number of inverter PCBs(Printed Circuit Boards) by decreasing the area of a backside of a bottom cover, which is occupied by an inverter. A backlight unit(150) includes a lamp unit, a connecting wire(171), a bottom cover(180), and a lamp driver(130a,130b). The lamp unit includes at least two lamps(170). The connecting wire electrically connects one end of one lamp to one end of the other lamp. The bottom cover receives the lamp unit. The lamp driver is located behind the bottom cover and electrically connected to the other end of each of the lamps.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME}

1 is a perspective view illustrating a rear surface of a conventional direct type backlight unit.

2 is an exploded perspective view illustrating a direct type liquid crystal display device according to an exemplary embodiment of the present invention.

3 is a view showing the lamp driver and the lamp of FIG.

<Brief description of the main parts of the drawing>

130a: first lamp driver 130b: second lamp driver

170a: odd numbered lamp 170b: even numbered lamp

171: connection wire

The present invention relates to a backlight unit, and more particularly, to a backlight unit and a liquid crystal display device having the same, which can improve space efficiency.

Liquid crystal display devices have been used in various fields as well as notebook PC and monitor market due to small size, light weight and low power consumption.

The liquid crystal display device is a light-receiving device for displaying an image by adjusting the amount of light from the outside. Accordingly, there is a need for a backlight unit for generating light for irradiating the liquid crystal display panel of the liquid crystal display device.

The backlight unit is classified into an edge type and a direct type according to the shape of the light source. The edge type system includes a light source on a side surface and a light guide plate on the same plane as the light source. Accordingly, the light emitted from the light source is irradiated to the liquid crystal display panel in front by the light guide plate. In the direct type, a plurality of light sources are provided on the back of the liquid crystal display panel. Accordingly, the light emitted from the plurality of light sources is directly irradiated to the front liquid crystal display panel.

Lamps installed in the backlight unit are classified into two types according to the position of the electrode. First is a Cold Cathode Fluorescent Lamp (CCFL) in which an electrode is built in the fluorescent lamp. Second, an External Electrode Fluorescent Lamp (EEFL) is provided with an electrode outside the fluorescent lamp. ) to be.

In general, the cold cathode fluorescent lamp (CCFL) is composed of a glass tube and an internal electrode disposed in the glass tube. Beads for sealing the glass tube by blocking the inside and the outside of the glass tube are attached to both ends of the glass tube of the cold cathode fluorescent lamp (CCFL), the lamp wire is inserted through the inside of the bead. The cold cathode fluorescent lamp CCFL is turned on by the lamp driving voltage generated by the inverter and supplied to the lamp wire.

When a plurality of cold cathode fluorescent lamps (CCFL) are installed and driven in parallel, resistance differences occur between the cold cathode fluorescent lamps (CCFL). Therefore, when any one of the plurality of cold cathode fluorescent lamps (CCFL) is turned on, the voltage increase is increased in the other cold cathode fluorescent lamps (CCFL), there is a problem that does not emit uniform light. Therefore, the cold cathode fluorescent lamp is not easily driven in parallel.

In spite of these problems, various backlight units have recently been developed that can drive cold cathode fluorescent lamps in parallel. Detailed description thereof will be described with reference to the accompanying drawings.

1 is a perspective view illustrating a rear surface of a conventional direct type backlight unit.

As shown in FIG. 1, a conventional direct type backlight unit includes a bottom cover 10 that accommodates and supports a plurality of lamps (not shown), and is disposed on a rear surface of the bottom cover 10 to drive the plurality of lamps. And first and second inverter printed circuit boards 20a and 20b mounted with lamp driving units 30a and 30b for generating a lamp driving voltage. In this case, the first and second inverter printed circuit boards 20a and 20b have the same size. The bottom cover 10 accommodates internal components including the plurality of lamps (not shown). In this case, the plurality of lamps are composed of a cold cathode fluorescent lamp or an external electrode fluorescent lamp.

The first inverter printed circuit board 20a is provided with a plurality of first lamp driver 30a for generating lamp driving voltages for driving the plurality of lamps.

The second inverter printed circuit board 20b includes a plurality of second lamp driver 30b for generating a lamp driving voltage for driving the plurality of lamps.

The first and second inverter printed circuit boards 20a and 20b are further provided with a plurality of connectors 50 respectively connected to lamp wires 30 drawn from both ends of the lamp.

The first lamp driving voltage generated by the first lamp driver 30a mounted on the first inverter printed circuit board 20a may be connected to one end of the plurality of lamps through the connector 50 and the lamp wire 60. Is supplied.

Similarly, the second lamp driving voltage generated by the first lamp driver 30b mounted on the second inverter printed circuit board 20b is connected to the plurality of lamps through the connector 50 and the lamp wire 60. It is supplied to the other end.

The lamp is driven by the first and second lamp driving voltages supplied to both ends of the plurality of lamps to generate light. The conventional backlight unit having such a structure is driven in a high-high manner to apply a high voltage to both ends of the lamp.

Since the first and second lamp drivers 30a and 30b and the plurality of connectors 50 are mounted on the first and second inverter printed circuit boards 20a and 20b, the overall area may be reduced by these components. There is an increasing problem.

In addition, as illustrated in FIG. 1, the first and second inverter printed circuit boards 20a and 20b may include the first and second lamp driving units 30a and 30b and the plurality of connectors 50. Because it includes unnecessary space in addition to the area, efficient space utilization is not possible.

In addition, the bottom case 10 may include a source printed circuit board on which a driving unit for driving a liquid crystal display panel is mounted, in addition to the first and second inverter printed circuit boards 20a and 20b. (10) The utilization area of the back is further reduced, which may be constrained by product design.

An object of the present invention is to provide a backlight unit that can effectively utilize the effective area.

An object of the present invention is to provide a backlight unit that can reduce the manufacturing cost.

A backlight unit according to a first embodiment of the present invention for achieving the above object, the lamp unit is defined by at least two or more lamps and provided with a plurality; A connection wire electrically connecting one end of the at least two lamps; A bottom cover to accommodate the lamp unit; And a lamp driver disposed on the bottom of the bottom cover and electrically connected to the other ends of the at least two lamps.

According to a second exemplary embodiment of the present invention, a liquid crystal display device includes: a lamp unit defined by at least two lamps and provided in plurality; A connection wire electrically connecting one end of the at least two lamps; A bottom cover to accommodate the lamp unit; A lamp driver disposed on a rear surface of the bottom cover and electrically connected to the other ends of the at least two lamps; And a liquid crystal display panel displaying a predetermined image by using light emitted from the lamp unit.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention.

2 is an exploded perspective view illustrating a direct type liquid crystal display device according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the liquid crystal display according to the exemplary embodiment of the present invention includes a liquid crystal display panel 110 for displaying an image, a backlight unit 150 for providing light to the liquid crystal display panel 110, and And a top case 100 coupled to the backlight unit 150 to surround the edge of the liquid crystal display panel 110.

Although not shown in detail, the liquid crystal display panel 110 includes an array substrate having a thin film transistor and a pixel electrode, a color filter substrate disposed on the array substrate and having a color filter and a common electrode, and a liquid crystal filled between the substrates. Consists of layers.

That is, after the array substrate and the color filter substrate are bonded together, the liquid crystal layer may be filled between the substrates to manufacture the liquid crystal display panel 110.

An electric field is generated by the voltage applied between the pixel electrode and the common electrode, and the liquid crystal is displaced by the electric field to adjust the transmittance of light to display an image.

One side of the liquid crystal display panel 110 is electrically connected to a liquid crystal display panel driver having a driving circuit for supplying a driving signal to the liquid crystal display panel 110 by a tape carrier package (TCP).

The liquid crystal display panel driver is electrically connected to the liquid crystal display panel 110 to supply control signals and data signals to a plurality of gate lines (not shown) and data lines (not shown) formed in the liquid crystal display panel 110. The pixels of the liquid crystal display panel 110 are driven.

The backlight unit 150 disposed on the rear surface of the liquid crystal display panel 110 to provide light has a bottom cover 180 having an open top and a rectangular shape, and is accommodated in the bottom cover 180 to emit light. A plurality of lamps 170 are provided.

Optical sheets 160 for diffusing and condensing light may be disposed on the plurality of lamps 170.

Although not shown in the drawing, a reflection sheet (not shown) for reflecting the light emitted from the plurality of lamps 170 to the liquid crystal display panel 110 may be applied or attached to the inner surface of the bottom cover 180. .

The plurality of lamps 170 may include a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL).

One end of the plurality of lamps 170 is provided with a plurality of connection wires 171. The connection wire 171 electrically connects one end of the odd and even lamps 170. That is, two adjacent lamps 170 may be electrically connected in series by the connection wires 170.

The connection wire 171 may be made of a conductive material having flexibility. That is, the connection wire 171 may be bent to have a U-shape, for example.

An inverter printed circuit board 120 mounted with first and second lamp drivers 130a and 130b for driving the plurality of lamps 170 is disposed at one end of the bottom cover 180.

Each of the first and second drivers 130a and 130b may be electrically connected to the odd and even lamps 17 using first and second lamp wires (not shown).

Each of the first and second lamp drivers 130a and 130b applies a high voltage having a different phase to the odd and even lamps 170.

In the direct type liquid crystal display according to the exemplary embodiment described above, the inverter printed circuit board 120 having the first and second lamp drivers 130a and 130b for driving the plurality of lamps 170 is bottomed. By being provided only at one end of the rear surface of the cover 180, the area occupied by the inverter printed circuit board 120 on the rear surface of the bottom cover 180 may be reduced, thereby limiting product design constraints.

In addition, the first and second lamp drivers 130a and 130b are mounted on one inverter printed circuit board 120 to apply high voltages having different phases to the odd and even lamps 170. The cost can be reduced by reducing the number of parts compared to the conventional high voltage applied at both ends.

FIG. 3 is a view illustrating the lamp driver and the lamps of FIG. 2.

2 and 3, one side of the odd-numbered lamp 170a and one side of the even-numbered lamp 170b are electrically connected by a connection wire 171.

Such odd-numbered lamps 170a and even-numbered lamps 170b are defined as one lamp unit.

Therefore, the backlight unit 150 may be provided with a plurality of lamp units.

Radix lamps 170a of the plurality of lamp units are electrically connected to the first lamp wire. Similarly, even-numbered lamps 170b provided in the plurality of lamp units are electrically connected to the second lamp wire in common.

The first lamp wire is electrically connected to the first lamp driver 130a, and the second lamp wire is electrically connected to the second lamp driver 130b.

The first lamp driver 130a generates a first driving voltage having a high level, for example, a first AC voltage. The second lamp driver 130b generates a high level second driving voltage, for example, a second AC voltage, having a phase difference of 180 degrees, which is out of phase with the first AC voltage.

The first AC voltage generated from the first lamp driver 130a is supplied to each odd number lamp 170a of the plurality of lamp units via the first lamp wire.

Similarly, the second AC voltage generated from the second lamp driver 130b is supplied to each even lamp 170b of the plurality of lamp units via the second lamp wire.

Accordingly, as the first AC voltage is supplied to the odd-numbered lamp 170a electrically connected to the connection wire 171, and the second AC voltage is supplied to the even-numbered lamp 170b, the odd-numbered lamp 170a and the even-numbered lamp 170a are supplied. The first lamp 170b is driven in a high-high manner to emit light.

In the present invention, two lamps 170a and 170b are connected in series by the connection wires 171, respectively, but not limited thereto, and three or more lamps 170a and 170b may be connected in series.

In the liquid crystal display according to the exemplary embodiment described above, one end of the odd-numbered lamp 170a and one end of the even-numbered lamp 170b are electrically connected by the connection wire 171, and the odd-numbered lamp ( The other end of 170a and the other end of the even-numbered lamp 171b each have a structure in which high voltages having different phases are applied.

Therefore, in the present invention, one inverter printed circuit board (120 of FIG. 2) mounted with the lamp driver (130a and 130b of FIG. 2) may be used even in high-high driving in which high voltage is applied to both ends of the lamp. That is, the present invention can reduce the cost by reducing the number of parts by reducing the inverter printed circuit board (120 of FIG. 2) to one.

In addition, the present invention reduces the area occupied by the inverter printed circuit board (120 in FIG. 2) on the back of the bottom cover (180 in FIG. 2) by reducing the inverter printed circuit board (120 in FIG. Design constraints can be reduced.

As described above, the LCD according to the present invention reduces the area of the inverter printed circuit board on the bottom of the bottom cover by reducing the inverter printed circuit board to one, thereby reducing the constraints of the product design.

In addition, the present invention is a structure that can apply different high voltage to one end of the lamp, it is possible to reduce the cost by reducing the number of parts compared to the conventional high voltage applied to both ends of the lamp.

Although the present invention has been described with reference to the embodiments, those skilled in the art may variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that.

Claims (10)

A lamp unit defined by at least two lamps and provided in plurality; A connection wire electrically connecting one end of the at least two lamps; A bottom cover to accommodate the lamp unit; And And a lamp driver disposed on a rear surface of the bottom cover and electrically connected to the other ends of the at least two lamps. The method of claim 1, The connection wire is a backlight unit, characterized in that for electrically connecting one end of the odd-numbered lamp and even-numbered lamp. The method of claim 1, And the lamp driver is configured to supply first and second driving voltages having different phases to the other ends of the at least two lamps. The method of claim 3, wherein And the first and second driving voltages have a high voltage. The method of claim 1, The lamp is a backlight unit, characterized in that any one of a cold cathode fluorescent lamp and an external electrode fluorescent lamp. A lamp unit defined by at least two lamps and provided in plurality; A connection wire electrically connecting one end of the at least two lamps; A bottom cover to accommodate the lamp unit; A lamp driver disposed on a rear surface of the bottom cover and electrically connected to the other ends of the at least two lamps; And And a liquid crystal display panel for displaying a predetermined image by using the light emitted from the lamp unit. The method of claim 6, And the connection wire electrically connects one end of the odd-numbered lamp and the even-numbered lamp. The method of claim 6, And the lamp driver is configured to supply first and second driving voltages having different phases to the other ends of the at least two lamps. The method of claim 8, And the first and second driving voltages have a high voltage. The method of claim 6, The lamp is any one of a cold cathode fluorescent lamp and an external electrode fluorescent lamp.

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