KR101684701B1 - Backlight unit and liquid crystal display device having the same - Google Patents

Abstract

The present invention discloses a backlight unit capable of preventing a driving failure.

The backlight unit of the present invention includes a plurality of light emitting diodes, a plurality of light emitting diodes, a printed circuit board having wiring for dividing the plurality of light emitting diodes into a plurality of blocks, and a backlight unit Wherein the first and third pads are connected to the first electrodes of the plurality of blocks on both sides of the pad portion of the flexible circuit board and the second and third pads of the plurality of blocks are disposed between the first and third pads, And a second pad connected to the electrode is disposed. Thus, the present invention can prevent an error when connecting the pad portion and the connection terminal.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight unit that can prevent a driving failure and a liquid crystal display device having the same.

A CRT (cathode ray tube), which is one of the widely used display devices, is mainly used for monitors such as a TV, a measurement device, and an information terminal device. However, due to the weight and size of the CRT itself, Could not respond positively to the response of

Therefore, in the trend of miniaturization and lightening of various electronic products, CRT has a certain limit in terms of weight and size, and is expected to be replaced with a liquid crystal display (LCD) using an electric field optical effect, a gas discharge A plasma display panel (PDP) using an electroluminescent effect, and an EL display device (ELD) using an electroluminescent effect. Among them, researches on a liquid crystal display device are being actively carried out.

Liquid crystal display devices are becoming more and more widespread due to features such as lightness, thinness, and low power consumption driving. Accordingly, the liquid crystal display device is proceeding in the direction of large-sized, thin, and low power consumption in response to the demand of the user.

2. Description of the Related Art [0002] A liquid crystal display device is a display device that displays an image by adjusting the amount of light transmitted through a liquid crystal, and is widely used because of its advantages such as thinness and low power consumption.

Since the liquid crystal display device is not a display device that emits light by itself, unlike a CRT, a backlight unit including a separate light source for providing light for visually expressing an image is provided on the back surface of the liquid crystal display panel .

The backlight unit is divided into the edge type and the direct type according to the position of the light source.

The edge type backlight unit is mainly applied to a liquid crystal display device of a comparatively small size such as a monitor of a laptop type computer and a desktop type computer, and has advantages of uniformity of light, long life, and advantageous in thinning of a liquid crystal display device .

The direct-type backlight unit has been developed mainly as the size of the liquid crystal display device starts to become larger than 20 inches, and a plurality of light sources are disposed on the lower surface of the diffusion plate to direct light directly to the front surface of the liquid crystal display panel will be. Such a direct-type backlight unit is mainly used for a large-screen liquid crystal display device which requires a high brightness because the utilization efficiency of light is higher than that of the edge type.

The backlight unit uses a plasma type light source such as a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent tube (HCFL), an external electrode fluorescent tube (EEFL), and an external & internal electrode fluorescent tube (EIFL) Or a light emitting diode (LED) is used.

Among these, light emitting diodes (LEDs) are widely used because they have long life, low power, small size and high durability.

The light emitting diodes are provided on the lower surface or the lower front surface of the liquid crystal display panel in a plurality of ways in accordance with the edge type or direct down type.

The light emitting diodes are mounted on the printed circuit board at regular intervals, and wiring for supplying driving signals to the light emitting diodes is formed on the printed circuit board.

The wiring is divided so that the light emitting diode can be driven by dividing the light emitting diode into a predetermined number of blocks.

In a typical liquid crystal display device, a flexible pristed circuit (FPC) is used for electrical connection between the LED driver and the printed circuit board on which the light emitting diode is mounted. However, the flexible circuit board has a structure in which there is no directionality of one surface and the other surface. When the LED driver is connected to the LED driver, the pad formed on one surface of the flexible circuit board and the pad of the LED driver must be assembled to come in contact with each other. When the other surface of the flexible circuit board and the pad of the LED driver are assembled to be in contact with each other, there is a problem that the LED driver is damaged due to a connection error.

The present invention provides a backlight unit capable of preventing a driving failure and a liquid crystal display device having the backlight unit.

A backlight unit according to an embodiment of the present invention includes a plurality of light emitting diodes, a printed circuit board on which a plurality of light emitting diodes are mounted, and a wiring for dividing the plurality of light emitting diodes into a plurality of blocks, And a flexible circuit board for connecting the driving unit. The first and third pads connected to the first electrodes of the plurality of blocks are disposed on both sides of the pad portion of the flexible circuit board and a second pad connected between the first and third pads is connected to the second electrode of the plurality of blocks, .

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The liquid crystal display device of the present invention includes a liquid crystal display panel, a plurality of light emitting diodes for providing light to the liquid crystal display panel, a plurality of light emitting diodes mounted on the liquid crystal display panel, and a wiring for dividing the plurality of light emitting diodes into a plurality of blocks And a flexible circuit board for connecting the printed circuit board and the backlight driver to the printed circuit board, wherein the first and third pads connected to the first electrodes of the plurality of blocks are disposed on both sides of the pad portion of the flexible circuit board And a second pad connected to the second electrode of the plurality of blocks is disposed between the first and third pads.

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The pad of the flexible circuit board connected to the connection terminal of the backlight driving unit is structured such that a second pad connected to the second electrode is formed at the center of the pad of the flexible circuit board so as to prevent connection errors between the first and second electrodes And first and third pads connected to the first electrode are formed on both sides of the second pad to prevent errors when connecting the pad portion and the connection terminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, embodiments of the present invention will be described in detail.

FIG. 1 is an exploded perspective view illustrating a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a view showing a wiring structure of a light emitting diode of the present invention, and FIG. 3 is a cross- FIG.

1 to 3, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal display panel 110, a backlight unit 120 for providing light to the liquid crystal display panel 110, And a panel guide 118 for supporting a lower edge of the liquid crystal display panel 110 and coupled with the backlight unit 120.

The liquid crystal display panel 110 includes a color filter substrate 111, a thin film transistor substrate 113 and a liquid crystal layer sandwiched between the two substrates so as to face each other and maintain a uniform cell gap.

Although not shown in detail in the drawing, the color filter substrate 111 and the thin film transistor substrate 113 will be described in detail. The thin film transistor substrate 113 defines pixels by intersecting a plurality of gate lines and data lines, A thin film transistor (TFT) is provided for each of the intersecting regions, and is connected in a one-to-one correspondence with the pixel electrodes mounted on the respective pixels. The color filter substrate 111 includes color filters of R, G, and B colors corresponding to the respective pixels, a black matrix for covering the gate lines, the data lines, the thin film transistors, and the like, .

A driving PCB 115 for supplying a driving signal to the gate line and the data line is provided at the edge of the liquid crystal display panel 110.

The driving PCB 115 is electrically connected to the liquid crystal display panel 110 by a chip on film (COF) 117. Here, the COF 117 may be changed to a TCP (Tape Carrier Package).

The backlight unit 120 disposed at the lower portion of the liquid crystal display panel 110 includes a bottom cover 180 having a rectangular box shape with an open top and a metal PCB 160 disposed inside one side of the bottom cover 180, , And a plurality of light emitting diodes (150) mounted on the metal PCB (160).

The backlight unit 120 includes a light guide plate 140 disposed in parallel with the light emitting diode 150 to convert the light into a light spot and a light guide plate 140 disposed below the light guide plate 140, A reflective sheet 170 for reflecting the light emitted from the light guide plate 140 in the direction of the light guide plate 110 and optical sheets 130 disposed on the light guide plate 140 for diffusing and condensing the light emitted from the light guide plate 140.

The backlight unit 120 includes a backlight driver 190 disposed below the bottom cover 180 and mounted with an LED driver for driving the LED 150. The backlight unit 190 includes a backlight unit 160, And a flexible circuit board 161 for electrically connecting to the driving unit 190.

The optical sheets 130 include a diffusion sheet 133 for diffusing light, a light condensing sheet 132 for condensing diffused light, a protective sheet 131 for protecting a light condensing pattern formed on the light condensing sheet 132 ).

The metal PCB 160 includes wires for inputting driving signals to the plurality of light emitting diodes 150, and the plurality of light emitting diodes 150 are divided into a plurality of blocks.

In the present invention, for example, a plurality of light emitting diodes 150 are divided into four blocks. However, the number of divided light emitting diodes 150 may be changed.

The flexible circuit board 161 includes a pad portion 163 at an end thereof and the pad portion 163 is inserted into a connection terminal (not shown) of the backlight driver 190, although not shown in the figure.

The plurality of light emitting diodes 150 divided into four blocks are arranged such that the second channels Ch2a to Ch2d connected to the second electrodes of the respective blocks are connected to the second pad Ch2 located at the center of the pad portion 163, To-one correspondence.

The first electrodes of each block are divided into two and connected to the first and third channels Ch1a, Ch1b, Ch3a and Ch3b.

The first and third channels Ch1a, Ch1b, Ch3a and Ch3b are connected to the first and third pads Ch1 and Ch3 located at the edge of the pad unit 163 in a one-to-one correspondence manner.

That is, in the present invention, the first electrodes of the plurality of light emitting diodes 150 divided into a plurality of blocks are divided and connected to the first and third pads Ch1 and Ch3.

Here, the flexible circuit board 161 has first to third pads Ch1, Ch2 and Ch3 having the same both sides of the pad portion 163.

FIG. 4 is a view showing one side of a pad portion of a flexible circuit board of the present invention and connection terminals of a backlight driving portion, and FIG. 5 is a view showing connection terminals of a backlight driving portion and the other side of the flexible circuit board pad portion of the present invention.

4, the flexible circuit board of the present invention includes first and third pads Ch1 and Ch3 disposed on both side edges of a pad portion 163a, first and third pads Ch1 and Ch3 And a second pad Ch2 positioned between the first and second electrodes.

The connection terminals 193 of the backlight driver include first to third connection pads 193a, 193b, and 193c connected to the first to third pads Ch1, Ch2, and Ch3.

The connection terminal 193 of the backlight driver supplies the first driving signal through the first and third connection pads 193a and 193c and the second driving signal through the second connection pad 193b. Here, the first and second driving signals have different voltage levels from each other.

5, the flexible printed circuit board of the present invention includes third and first pads Ch3 and Ch1 located on both side edges of the pad portion 163b, third and first pads Ch3 and Ch1 And a second pad Ch2 positioned between the first and second electrodes.

The connection terminals 193 of the backlight driver include first to third connection pads 193a, 193b, and 193c connected to the third to the first pads Ch3, Ch2, and Ch1.

The connection terminal 193 of the backlight driver supplies the first driving signal through the first and third connection pads 193a and 193c and the second driving signal through the second connection pad 193b.

The structure of the pad portion of the flexible circuit board connected to the connection terminal 193 of the backlight driving portion is structured such that the first and second electrodes connected to the second electrode are connected to the central portion of the pad of the flexible circuit board, And the first and third pads Ch1 and Ch3 connected to the first electrode are formed on both sides of the second pad Ch2 to connect the pad portion and the connection terminal 193 Errors can be prevented.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

1 is an exploded perspective view illustrating a liquid crystal display device according to an embodiment of the present invention.

2 is a view showing a wiring structure of a light emitting diode of the present invention.

3 is a view showing a flexible circuit board of the present invention.

4 is a view illustrating one side of a pad portion of a flexible circuit board and connection terminals of a backlight driving portion of the present invention.

5 is a view illustrating connection terminals of the backlight driver and the other surface of the flexible circuit board pad portion of the present invention.

Claims (12)

A plurality of light emitting diodes; A printed circuit board on which the plurality of light emitting diodes are mounted and having wirings for dividing the plurality of light emitting diodes into a plurality of blocks; And And a flexible circuit board for connecting the printed circuit board and the backlight driver, The first and third pads connected to the first electrodes of the plurality of blocks are disposed on both sides of the pad portion of the flexible circuit board and the first and third pads are connected to the second electrodes of the plurality of blocks, A second pad is disposed, Wherein the first pad is symmetrical to the third pad with respect to the second pad. The method according to claim 1, Wherein the first to third pads are disposed on both sides of the pad portion of the flexible circuit board. The method according to claim 1, A pad portion of the flexible circuit board is connected to a connection terminal of the backlight driving portion, the connection terminal includes first and third connection pads connected to the first and third pads, and a second connection A backlight unit comprising a pad. The method of claim 3, Wherein the first and third connection pads are supplied with a first driving signal and the second connection pad is supplied with a second driving signal. 5. The method of claim 4, Wherein the first and second driving signals have different voltage levels from each other. A liquid crystal display panel; A plurality of light emitting diodes for providing light to the liquid crystal display panel; A printed circuit board on which the plurality of light emitting diodes are mounted and having wirings for dividing the plurality of light emitting diodes into a plurality of blocks; And And a flexible circuit board for connecting the printed circuit board and the backlight driver, The first and third pads connected to the first electrodes of the plurality of blocks are disposed on both sides of the pad portion of the flexible circuit board and the first and third pads are connected to the second electrodes of the plurality of blocks, A second pad is disposed, Wherein the first pad is symmetrical to the third pad with respect to the second pad. The method according to claim 1, The flexible circuit board includes: First and third channels connecting the first electrode and the first and third pads, and a second channel connecting the second electrode and the second pad. The method according to claim 6, Wherein the first to third pads are disposed on both sides of the pad portion of the flexible circuit board. The method according to claim 6, A pad portion of the flexible circuit board is connected to a connection terminal of the backlight driving portion, the connection terminal includes first and third connection pads connected to the first and third pads, and a second connection A liquid crystal display comprising a pad. 10. The method of claim 9, Wherein a first driving signal is supplied to the first and third connection pads and a second driving signal is supplied to the second connection pad. 11. The method of claim 10, Wherein the first and second driving signals have different voltage levels from each other. The method according to claim 6, The flexible circuit board includes: First and third channels connecting the first electrode and the first and third pads, and a second channel connecting the second electrode and the second pad.

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