KR20070121244A - Back light unit and liquid crystal display module including the same - Google Patents

Abstract

A backlight unit and an LCD module having the same are provided to prevent the reduction of brightness due to movement of an LED occurring when mounting the LED on a PCB by forming a plurality of LED pads and PCB pads for one LED and minimize the sizes of the LED pads. An LED(150) for supplying light is mounted on a PCB(170), wherein the PCB has wires for supplying an electric power to the LED. At least two LED pads(152) are formed at both ends of the LED, wherein the LED pads transfer the electric power, which is supplied from the PCB, to the LED. A plurality of PCB pads(172) are formed on the PCB correspondingly to the LED pads, wherein the PCB pads fix the LED to the PCB. The PCB pad has a size for receiving the LED pad.

Description

BACK LIGHT UNIT AND LIQUID CRYSTAL DISPLAY MODULE INCLUDING THE SAME}

1 is a cross-sectional view showing a liquid crystal display module according to the present invention.

2 is a perspective view illustrating a light emitting diode mounted on a circuit board according to the present invention.

3 is a plan view showing a light emitting diode mounted on a circuit board according to the present invention.

4 is an enlarged view illustrating in detail one of the circuit board pads on which the light emitting diode pads of FIG. 3 are mounted.

<Short description of drawing symbols>

100: liquid crystal display module 130: optical sheet

140: light guide plate 150: light emitting diode

152: light emitting diode pad 160: reflective sheet

170: circuit board 172: circuit board pad

200: mold frame 210: top chassis

220: bottom chassis 300: liquid crystal display panel

310: color filter substrate 320: thin film transistor substrate

330 driving circuit S: gap between light emitting diode and light guide plate

A: Short side length of light emitting diode pad

B: distance between one side of a circuit board pad and one side of a light emitting diode pad

C: spacing between the other side of the circuit board pad and the other side of the light emitting diode pad

D: Short side length of circuit board pad

The present invention relates to a backlight unit and a liquid crystal display module having the same, and more particularly, to a backlight unit and a liquid crystal display module having the same, which can improve luminance and prevent display defects.

In general, a liquid crystal display module (LCD) is a representative flat panel display module that displays an image by adjusting a transmission amount of a light beam to correspond to an image signal. In particular, the liquid crystal display module has a tendency that its application range is gradually widening due to features such as light weight, thinness, low power consumption. According to this trend, the liquid crystal display module has been applied as an office automation device and a notebook computer display module. In addition, the liquid crystal display module is progressing in the direction of large screen, high definition, and low power consumption in response to user demands.

Since the liquid crystal display panel of the liquid crystal display module does not emit light by itself, the liquid crystal display module includes a backlight unit for providing light to the liquid crystal display panel.

The backlight unit includes a light emitting diode as a light source, a circuit board for supplying power to the light emitting diode, and a light guide plate for surface-lighting the light emitted from the light emitting diode.

The light emitting diode is mounted on the circuit board by a surface mount technology (SMT), which is a method of placing and soldering a component on a circuit board.

When the light emitting diode is mounted on the circuit board, the light emitting diode pad attached to the light emitting diode is positioned at the center of the circuit board pad and is heated to attach the light emitting diode pad and the circuit board pad. However, since the mounting ability of the surface mounting technology is not accurate, the light emitting diodes are misaligned and thus the luminance is decreased, and thus, display defects occur because the light emitting diodes and the light guide plate are not formed in parallel.

In addition, the distance between the light emitting diode and the light guide plate is far, so that light of the light emitting diode is not transmitted to the light guide plate, which causes a large amount of luminance deviation. Increasing the current of the light emitting diode may improve luminance. Therefore, a problem arises in that a large amount of power consumption is used to increase luminance.

Accordingly, the technical problem to be achieved by the present invention is to form a plurality of LED pads and a plurality of circuit board pads, and to minimize the size of the circuit board pads to prevent the reduction of brightness and display failure due to the movement of the mounting position generated when the LED is mounted. It is to provide a backlight unit and a liquid crystal display module having the same.

In order to achieve the above object, the present invention provides a light emitting diode for supplying light, a circuit board on which the light emitting diode is mounted to supply power to the light emitting diode, and at least two formed on each of both ends of the light emitting diode. And a light emitting diode pad for transmitting power supplied from the circuit board to the light emitting diode, and a circuit board pad corresponding to the light emitting diode pad on the circuit board to fix the light emitting diode to the circuit board. It provides a backlight unit.

The light guide plate may further include a light guide plate for surface light emission from the light emitting diodes.

In addition, the circuit board pad is characterized in that it is formed in a size that can accommodate the light emitting diode pad.

In this case, a distance between one side of the circuit board pad and one side of the light emitting diode pad and a distance between the other side of the circuit board pad and the other side of the light emitting diode pad in the longitudinal direction are formed in a range of 0.08 mm to 0.12 mm.

In order to achieve the above object, the present invention includes a liquid crystal display panel for implementing an image, a backlight unit for supplying light to the liquid crystal display panel, the backlight unit is a light emitting diode for supplying light, and the light emitting diode A circuit board on which a wiring board is mounted to supply power to the light emitting diode, and at least two light emitting diode pads are formed on each end of each of the light emitting diodes to transmit power supplied from the circuit board to the light emitting diodes; And a circuit board pad corresponding to the light emitting diode pad and fixing the light emitting diode to the circuit board.

The apparatus may further include a light guide plate guiding the light emitted from the light emitting diode to a surface light source and guiding the light to the liquid crystal display panel.

In addition, the circuit board pad is characterized in that it is formed in a size that can accommodate the light emitting diode pad.

In this case, a distance between one side of the circuit board pad and one side of the light emitting diode pad and a distance between the other side of the circuit board pad and the other side of the light emitting diode pad in the longitudinal direction are formed in a range of 0.08 mm to 0.12 mm.

Other features of the present invention will be apparent from the description of the embodiments with reference to the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a cross-sectional view showing a liquid crystal display module according to the present invention. These embodiments of the present invention are merely to illustrate the invention, but the present invention is not limited thereto.

Referring to FIG. 1, the liquid crystal display module 100 according to the present invention includes a liquid crystal display panel 300 for largely implementing an image, a driving circuit 330 for driving the liquid crystal display panel 300, and a liquid crystal display panel. And a backlight unit (not shown) for supplying light to the 300.

The liquid crystal display panel 300 includes a liquid crystal controlling light transmittance, a color filter substrate 310 and a thin film transistor substrate 320 bonded together with the liquid crystal interposed therebetween.

The liquid crystal is rotated by the difference between the common voltage from the common electrode of the color filter substrate 310 and the pixel voltage from the pixel electrode of the thin film transistor substrate 320 to adjust the light transmittance. To this end, the liquid crystal is made of a material having dielectric anisotropy and refractive index anisotropy.

The color filter substrate 310 is formed in a matrix on a substrate such as glass to block light, and a red, green, and blue color filter formed in a region partitioned by the black matrix to realize color, and a liquid crystal. It includes a common electrode for applying a common voltage to the.

The thin film transistor substrate 320 is formed on a substrate such as glass by including a thin film transistor formed in a pixel region defined by an intersection of a data line and a gate line and a pixel electrode applying a pixel voltage to the liquid crystal. The thin film transistor transfers the image signal supplied from the data line to the pixel electrode in response to the scan signal supplied from the gate line.

The driving circuit 330 is mounted on a thin film transistor substrate 320 in a chip on glass (COG) manner and provides a gate driving circuit for supplying a scan signal to a gate line and an image signal for a data line. The data driver circuit includes a timing controller for controlling driving timing of the gate driver circuit and the data driver circuit, and a power supply unit for supplying power signals necessary for driving the liquid crystal display panel 300 and the driver circuits.

The backlight unit includes a light emitting diode 150 for supplying light, a light guide plate 140 for increasing the efficiency of the liquid crystal display panel 300, and a wiring for mounting the light emitting diode 150 to supply power to the light emitting diode 150. At least two circuit boards 170 and at least two ends of each of the light emitting diodes 150 are formed to transmit the power supplied from the circuit board 170 to the light emitting diodes 150 and the circuit boards. A circuit board pad 172 that corresponds to the light emitting diode pad 152 to fix the light emitting diode 150 to the circuit board 170 at 170.

The light emitting diodes 150 are supplied with power from the circuit board 170 to generate light, and the light emitted from the light emitting diodes 150 is light guide plate 140 through an incident surface located on at least one side of the light guide plate 140. Is incident on.

The light guide plate 140 converts a line light source incident from the light emitting diode 150 through the incident surface into a surface light source and guides the light source to the liquid crystal display panel 300, and is mainly made of an acrylic material.

The circuit board 170 is formed of a printed circuit board (PCB) or a flexible printed circuit board (FPC). At least one light emitting diode 150 is mounted on the circuit board 170 and supplies light to the light guide plate 140. The circuit board 170 supplies a driving voltage to the light emitting diodes 150 and emits heat emitted from the light emitting diodes 150 to the outside. In addition, the circuit board 170 supplies a signal to the driving circuit 330 mounted on the thin film transistor substrate 320 to display an image on the liquid crystal display panel 300.

2 is a perspective view showing a light emitting diode mounted on a circuit board according to the present invention, and FIG. 3 is a plan view showing a light emitting diode mounted on a circuit board according to the present invention.

2 and 3, at least two light emitting diodes 150 are formed at each of both ends of the light emitting diodes 150 to transmit power supplied from the circuit board 170 to the light emitting diodes 150. 152. In this case, the light emitting diode pads 152 are formed at regular intervals, one on each of the upper and lower ends of the light emitting diodes 150.

The circuit board 170 includes a circuit board pad 172 that corresponds to the light emitting diode pad 152 and fixes the light emitting diode 150 to the circuit board 170. Therefore, according to the embodiment of the present invention, four circuit board pads 172 are formed on the circuit board 170 by the number of light emitting diodes 150.

4 is an enlarged view illustrating in detail one of the circuit board pads on which the light emitting diode pads of FIG. 3 are mounted.

Referring to FIG. 4, the circuit board pad 172 is formed to have a size that can accommodate the light emitting diode pad 152.

Specifically, the distance B between one side of the circuit board pad 172 and one side of the light emitting diode pad 152 and the other side of the circuit board pad 172 and the other side of the light emitting diode pad 152 in the longitudinal direction. The interval C is formed from 0.08 mm to 0.12 mm.

For example, an interval B between one side of the circuit board pad 172 and one side of the light emitting diode pad 152 and a distance between the other side of the circuit board pad 172 and the other side of the light emitting diode pad 152 in the longitudinal direction ( When C) is smaller than 0.08 mm, the mounting area of the circuit board pad 172 is small even when the light emitting diode pad 152 is slightly displaced in the right position when the light emitting diode 150 is mounted on the circuit board 170. The diode 150 is easily separated, resulting in mounting failure. A plurality of light emitting diodes 150 are mounted on the circuit board 170 in series, and the light emitting diodes 150 are not connected to the light emitting diodes 150 where the mounting defects are generated. Neither of the light emitting diodes 150 generates light.

Meanwhile, a distance B between one side of the circuit board pad 172 and one side of the light emitting diode pad 152 and a distance C between the other side of the circuit board pad 172 and the other side of the light emitting diode pad 152 in the longitudinal direction. When larger than 0.12 mm, the light emitting diode 150 has a large mounting area of the circuit board pad 172 and is easily twisted and mounted on the circuit board 170. Therefore, since the light emitting diodes 150 are not mounted in parallel with the light guide plate 140, the luminance decreases and display defects occur.

Therefore, the distance B between one side of the circuit board pad 172 and one side of the light emitting diode pad 152 and the distance C between the other side of the circuit board pad 172 and the other side of the light emitting diode pad 152 in the longitudinal direction. Most preferably, the silver is formed from 0.08 mm to 0.12 mm.

The short side length D of the circuit board pad 172 is a distance B between one side of the circuit board pad 172 and one side of the light emitting diode pad 152 and the other side of the circuit board pad 172 and the light emitting diode in the longitudinal direction. The distance C between the other side of the pad 152 and the short side length A of the light emitting diode pad 152 are added together.

The distance between the light emitting diodes 150 and the light guide plate 140 (S: shown in FIG. 1) is a distance B between one side of the circuit board pad 172 and one side of the light emitting diode pad 152 and the circuit board in the longitudinal direction. This is caused by the distance C between the other side of the pad 172 and the other side of the light emitting diode pad 152. Therefore, the distance S between the light emitting diodes 150 and the light guide plate 140 is reduced due to the reduction of the circuit board pads 172. For this reason, the light emitted from the light emitting diodes 150 is uniformly supplied to the light guide plate 140 so that a deviation in luminance does not occur.

The light emitting diodes 150 are mounted on the circuit board 170 by a surface mounting method in which a component is placed on the circuit board 170 and soldered. In this case, the LED pad 152 and the circuit board pad 172 are soldered by applying heat. Therefore, the light emitting diode pad 152 and the circuit board pad 172 are formed of lead or the like which can be easily melted by applying heat.

The light emitting diode pad 152 is preferably located at the center of the circuit board pad 172 in the width direction. When the light emitting diode pads 152 are mounted above or below the center of the circuit board pad 172 in the width direction, misalignment of the light emitting diodes 150 may cause luminance to decrease.

At least two ends are formed at each end to correspond to the light emitting diodes 150 including the light emitting diode pads 152 for transmitting power supplied from the circuit board 170 to the light emitting diodes 150 and the light emitting diode pads 152. The backlight unit including the circuit board 170 having the circuit board pad 172 to fix the light emitting diodes 150 to the circuit board 170 further includes an optical sheet 130 and a reflective sheet 160.

The optical sheet 130 is a diffusion sheet that scatters the light emitted from the light guide plate 140 and spreads it evenly, and a prism sheet and scratches that raise the brightness by refracting and condensing the light emitted from the diffusion sheet are easy and moiré phenomenon. Two or more protective sheets to protect the prism sheet that may appear and to spread the light to widen the viewing angle narrowed by the prism sheet, and to improve the luminance of the liquid crystal display module 100 of the brightness enhancement sheet in general It consists of.

The reflective sheet 160 reflects light emitted from the lower portion of the light guide plate 140 toward the light guide plate 140. To this end, the reflective sheet 160 is coated with a material having a high reflectance on the base material. That is, Ag, Ti, etc. are mainly coated with a reflective member on a base material such as stainless steel (SUS), brass, aluminum, and polyethylene terephthalate (PET).

In addition, the liquid crystal display module 100 requires a mold frame 200, a top chassis 210, and a bottom chassis 220 to fix the backlight unit and the liquid crystal display panel 300.

The mold frame 200 is a mold, and the side wall surface thereof is formed into a stepped stepped surface. The backlight unit is mounted on the innermost layer of the mold frame 200 and the liquid crystal display panel 300 is mounted on the optical sheet 130.

The top chassis 210 has an opening in the center thereof so that the liquid crystal display panel 300, which is the display area of the liquid crystal display module 100, may be exposed, and the top chassis 210 may be formed of a metal or plastic material. In addition, the top chassis 210 protects the liquid crystal display panel 300 and the backlight unit by an impact applied from the outside.

In the bottom chassis 220, the backlight unit, the liquid crystal display panel 300, and the mold frame 200 are sequentially stacked. The bottom chassis 220 protects the stored backlight unit, the liquid crystal display panel 300, and the mold frame 200 from an external impact, and is formed of a metal or plastic material.

As described above, the backlight unit and the liquid crystal display module having the same include the light emitting diode pad of the light emitting diode and the circuit board pad of the circuit board. Specifically, at least two light emitting diode pads are formed at both ends of the light emitting diodes. The circuit board pad has a size that can accommodate the light emitting diode pad at a position corresponding to the light emitting diode pad on the circuit board. At this time, the light emitting diode prevents movement of the light emitting diode due to the small space that can be moved in the pad of the circuit board, thereby preventing the light emitting diode from being misaligned. Such mounting can prevent a decrease in luminance, and display defects are solved because the light emitting diodes and the light guide plate are mounted in the same manner.

In addition, the gap between the light emitting diode and the light guide plate is narrowed due to the reduction of the circuit board pads, so that no luminance deviation occurs and no current is used to increase the brightness, thereby reducing power consumption.

In the detailed description of the present invention described above with reference to the preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge of the present invention described in the claims to be described later It will be understood that various modifications and changes can be made in the present invention without departing from the spirit and 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.

Claims (8)

A light emitting diode for supplying light; A circuit board on which the light emitting diodes are mounted to form a wiring for supplying power to the light emitting diodes; At least two light emitting diode pads formed at both ends of the light emitting diodes to transfer power supplied from the circuit board to the light emitting diodes; And a circuit board pad corresponding to the light emitting diode pad on the circuit board to fix the light emitting diode to the circuit board. The method of claim 1, And a light guide plate for surface-lightening the light emitted from the light emitting diodes. The method of claim 1, The circuit board pad is a backlight unit, characterized in that formed to a size that can accommodate the light emitting diode pad. The method of claim 1, And a distance between one side of the circuit board pad and one side of the light emitting diode pad and a distance between the other side of the circuit board pad and the other side of the light emitting diode pad in a length direction of 0.08 mm to 0.12 mm. A liquid crystal display panel for implementing an image; A backlight unit for supplying light to the liquid crystal display panel; The backlight unit A light emitting diode for supplying light; A circuit board on which the light emitting diodes are mounted to form a wiring for supplying power to the light emitting diodes; At least two light emitting diode pads formed at both ends of the light emitting diodes to transfer power supplied from the circuit board to the light emitting diodes; And a circuit board pad corresponding to the light emitting diode pad on the circuit board to fix the light emitting diode to the circuit board. The method of claim 5, And a light guide plate guiding the light emitted from the light emitting diode to a surface light source and guiding the light to the liquid crystal display panel. The method of claim 5, And the circuit board pad is formed to have a size that can accommodate the light emitting diode pad. The method of claim 5, And a distance between one side of the circuit board pad and one side of the light emitting diode pad and a distance between the other side of the circuit board pad and the other side of the light emitting diode pad in a length direction of 0.08 mm to 0.12 mm.

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