KR20070121908A - Backlight unit and liquid crystal display device using the same - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) using the backlight unit are provided to facilitate color mixture using LEDs(Light Emitting Diode) and reflecting cups for mixing lights generated from the LEDs and reflecting the mixed light to an LCD panel to reduce the thickness of the backlight unit and the LCD using the backlight unit. A backlight unit includes a point light source(110), a printed circuit board(118), and a plurality of wires(146). The printed circuit board provides a driving voltage to the point light source through a first connector(118a). One end of Each of the plurality of wires is coupled to the point light source and the other end of the plurality of wires is connected to a second connector. The plurality of wires is connected/disconnected to/from the printed circuit board through the first and second connectors. The backlight unit further includes a reflecting cup in which the point light source is located.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME}

1 is a view showing a conventional liquid crystal display device using the LED backlight unit.

2 is a cross-sectional view of the LED unit shown in FIG.

3 and 4 is a view showing a light emission pattern of a conventional LED backlight.

5 shows a layout of a conventional LED backlight;

6 is a view showing a liquid crystal display device according to the present invention.

7 is a cross-sectional view of the LED unit shown in FIG.

8A and 8B are diagrams showing the LED arrangement of the LED unit.

9 is a view showing another example of mounting of the LEd unit;

<Brief description of symbols for the main parts of the drawings>

2, 102 liquid crystal display panel 4, 104 optical sheet

6, 106 diffuser 8: light guide plate

10, 110: LED part 12, 112: reflection sheet

14 heat sink 16 soldering leg

18, 118: MCPCB 20, 120: bottom cover

22: backlight unit 24: mounting member

26: LED 28: silicon member

30: lens 32: LED reflector

140: reflective cup 142: cap

144: LED unit 146: cable

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a liquid crystal display device using the same, and more particularly, to a backlight unit having a high light efficiency and easy to thin and independently replaceable light sources, and a liquid crystal display device using the same.

In general, the liquid crystal display device has a trend that the application range is gradually widened due to the characteristics such as light weight, thin, low power consumption. In accordance with this trend, liquid crystal displays are used in office automation equipment, audio / video equipment, and the like. In such a liquid crystal display, a transmission amount of a light beam is adjusted according to a signal applied to a plurality of control switches arranged in a matrix to display a desired image on a screen.

Since the liquid crystal display is not a self-luminous display, a separate light source such as a backlight is required.

The backlight unit includes a direct type and an edge type according to the position of the light source. In the edge type method, a light source is installed at the edge of the liquid crystal display device, and the light incident from the light source is diffused to be incident on the entire surface of the liquid crystal display panel through the light guide plate and the plurality of optical sheets, and the light is collected by the liquid crystal display panel. To be possible. In the direct type, a plurality of light sources are disposed below the liquid crystal display panel, and the light incident from the light sources is directly dimmed to the entire surface of the liquid crystal display panel through the diffusion plate and the plurality of optical sheets, Allow it to collect.

Recently, the direct type backlight having higher luminance, light uniformity and color purity than the edge type has been used more mainly in LCD TVs.

The types of lamps used in the direct type backlight unit include Cold Cathode Flourscent Lamps ("CCFL"), External Electrode Flourscent Lamps ("EEFL"), and Light Emitting Diodes: "LED").

The dual LED backlight unit has been spotlighted as a next-generation light source because of its small size, high brightness, and excellent energy saving effect.

1 is a view showing a conventional liquid crystal display using the LED backlight unit.

Referring to FIG. 1, a conventional liquid crystal display device using an LED backlight unit includes a liquid crystal display panel 2, a backlight unit 22 for irradiating light to the liquid crystal display panel 2, a liquid crystal display panel 2, and a liquid crystal display panel 2. A bottom cover 20 for storing the backlight unit 22 is provided.

First, in the liquid crystal display panel 2, a plurality of data lines and a plurality of gate lines are arranged to cross each other, and liquid crystal cells are arranged in an active matrix form between the upper substrate and the lower substrate. In the liquid crystal display panel 2, pixel electrodes and common electrodes for applying an electric field to each of the liquid crystal cells are formed. Thin film transistors are formed at the intersection of the data lines and the gate lines to switch the data voltage to be applied to the pixel electrode in response to the scan signal. Gate drive integrated circuits and data drive integrated circuits are electrically connected to the liquid crystal display panel 2 through a tape carrier package.

The backlight unit 22 includes an LED unit 10, a reflective sheet 12, a heat sink 14, a soldering leg 16, a MCPCB (Metal Core Printed Circuit Board) 18, a light guide plate 8, The diffuser plate 6 and the optical sheets 4 are provided.

The LED unit 10 formed by being seated on the top of the heat sink 14 generates light and has a cross-sectional view as shown in FIG. 2. Referring to FIG. 2, the LED unit 10 includes an LED 26 mounted on the mount member 24, a silicon member 28 formed to cover the LED 26, a mount member 24, and an LED 26. ) And a lens 30 formed to cover the silicon member 28. The LED 26 is formed of any one of red (R), green (G), and blue (B) light emitting diodes. The lens 30 includes a hemispherical first portion and an inverted truncated second portion formed on the surface of the first portion corresponding to the LED 26. The LED reflector 32 is formed on the upper surface of the second portion.

The reflective sheet 12 is formed of aluminum or the like to reflect the light generated from the LED unit 10 toward the liquid crystal display panel 2.

The heat sink 14 transfers heat generated from the LED unit 10 to the MCPCB 18, and the MCPCB 18 is formed of an aluminum substrate to radiate heat generated from the LED unit 10, and soldering is performed. Power is supplied to the LED unit 10 through the legs 16.

The light guide plate 8 serves to mix the light generated by the LED unit 10 and to guide the light toward the liquid crystal display panel 2, and mainly a polymethyl methacrylate (PMMA) material is used.

The diffusion plate 6 serves to diffuse the light passing through the light guide plate 8 to the entire surface of the liquid crystal display panel 2.

The optical sheets 4 include at least one diffusion sheet and at least one prism sheet, and uniformly irradiate the light incident from the diffuser plate 6 onto the entire liquid crystal display panel 2 and perpendicular to the display surface. It serves to condense the light to the front of the display surface by bending the light propagation path in the direction of.

The bottom cover 20 is manufactured in a container structure in which the liquid crystal display panel 2 and the backlight unit 22 are supported and accommodated.

3 and 4 are diagrams showing light emission patterns of LED backlights. Referring to FIGS. 3 and 4, light emission of the LED backlight is as follows.

Since the lens 30 of the LED backlight LED portion 10 includes the first portion and the second portion having the LED reflector 32 as described above with reference to FIG. 2, as shown in FIGS. 3 and 4. It has the same light emission pattern. That is, the light generated by the LED 26 toward the liquid crystal display panel 2 as straight light is reflected by the LED reflector 32 of the second portion of the lens 30 and is generated toward the side of the first portion of the lens 30. The light that passes through the lens 30. Accordingly, the light generated from the red light emitting diode, the green light emitting diode, and the blue light emitting diode mounted in each LED unit 10 is not directly irradiated to the liquid crystal display panel 2 with the red light, the green light, and the blue light, respectively. As shown in FIG. 4, the mixture produces white light.

However, as can be seen from FIGS. 3 and 4, since the light generated from the LED unit 10 is mostly inclined light, the white light after the color is mixed also becomes inclined light and is directed toward the liquid crystal display panel 2. In order to increase the haze (Haze) of the diffusion plate, which leads to light loss.

In addition, as described above, in order to generate white light, a space in which red, green, and blue light may be mixed should be provided to a sufficient thickness, and as shown in FIGS. 1 and 4 to improve color mixing characteristics. The light guide plate 8 is required. Accordingly, the backlight unit using the conventional LED has a limitation in thinning. In addition, the power consumption is increased to compensate for the brightness degradation caused by the light lost when passing through the light guide plate 8, and the light efficiency is lowered as the temperature is increased as a whole of the LED and the backlight unit due to the increased power consumption. . In addition, even if light passes through the light guide plate 8, color mixing is not performed properly, and thus a difference occurs in luminance of a portion where the LED unit 10 is located and a portion that is not located.

5 is a view briefly showing the arrangement of the LED unit 10 and the MCPCB 18 of the conventional backlight unit.

Referring to FIG. 5, the conventional backlight unit forms a plurality of LED units 10 in each of the plurality of MCPCBs 18 disposed on the bottom cover 20. That is, the LED unit 10 is a predetermined number is attached in series on one MCPCB 18 in a group to receive an electrical signal. At this time, each LED unit 10 is soldered to the MCPCB 18 through the soldering leg 16 shown in FIG. Therefore, when a failure occurs in any one of the LED unit 10 mounted on a specific MCPCB 18, there is a problem that the signal supply is also cut off to the other LED unit 10 formed in the MCPCB 18.

Accordingly, an object of the present invention is to provide a backlight unit having a high light efficiency and easy thinning and individually replacing a light source and a liquid crystal display device using the same.

In order to achieve the above object, the backlight unit according to the present invention comprises a point light source; A printed circuit board supplying driving power to the point light source through a first connector; And a plurality of wires connected at one side to the point light source and connected to a second connector electrically connected to the first connector and detachable from the printed circuit board.

The second connector is commonly connected to the n number of point light sources.

The backlight unit further includes a reflective cup assembled to the point light source such that the point light source is located therein.

N point light sources are positioned in one reflection cup.

The wiring is a flexible flat cable.

The backlight unit further includes an optical member disposed on the light sources.

The backlight unit further includes a bottom cover to accommodate the printed circuit board, the point light source, and the wiring.

The backlight unit may further include a reflective sheet having a portion except for the point light source and disposed in the bottom cover on which the printed circuit board is formed.

The point light source is a light emitting diode.

Inside the reflective cup, any one of a red light emitting diode, a green light emitting diode, and a red light emitting diode is disposed.

At least one red light emitting diode, at least one green light emitting diode, and at least one blue light emitting diode are disposed in the reflection cup.

The reflective cup includes a transparent cap that shields the opening surface of the reflective cup.

A reflection pattern or a haze pattern is formed at a portion of the transparent cap that faces the position of the point light source.

Liquid crystal display device according to the present invention comprises a liquid crystal display panel; And a printed circuit board for supplying driving power to the point light source through a point light source, a first connector, and a second connector connected to one side of the point light source and electrically connected to the first connector. It includes a backlight unit for irradiating light to the liquid crystal display panel having a plurality of wiring detachable to the circuit board.

Other objects and advantages of the present invention in addition to the above object will be apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 6 to 9B.

6 is a view showing a liquid crystal display device according to the present invention.

Referring to FIG. 6, a liquid crystal display according to the present invention includes a liquid crystal display panel 102, a backlight unit for irradiating light to the liquid crystal display panel 102, and a bottom for accommodating the liquid crystal display panel 102 and the backlight unit. The cover 120 is provided.

First, in the liquid crystal display panel 102, a plurality of data lines and a plurality of gate lines are arranged to cross each other, and liquid crystal cells are arranged in an active matrix form between the upper substrate and the lower substrate. In addition, the liquid crystal display panel 102 includes pixel electrodes and common electrodes for applying an electric field to each of the liquid crystal cells. Thin film transistors are formed at the intersection of the data lines and the gate lines to switch the data voltage to be applied to the pixel electrode in response to the scan signal. Gate drive integrated circuits and data drive integrated circuits are electrically connected to the liquid crystal display panel 102 through a tape carrier package.

The backlight unit includes an LED unit 144 and an optical member including a diffuser plate 106 and optical sheets 104.

6 and 7, the LED unit 144 includes the LED unit 110 and the reflective cup 140 to generate light and reflect the light toward the liquid crystal display panel 102.

The reflecting cup 112 is formed of a reflective material such as aluminum, and has an upper portion, and a cross section is a circle or a polygon, and has an inner diameter that increases toward the upper portion.

The LED unit 110 is provided with an LED to generate light and is located on the inner bottom of the reflective cup 140 to be surrounded by the side by the reflective cup 112, as shown in FIG. 8A. It may be formed by including any one of the blue LED, or may include at least one red LED, at least one green LED, at least one blue LED as shown in FIG. When one LED is disposed in one LED unit 144 as shown in FIG. 8A, the light reflected from the side of the reflective cup 140 is mixed outside the reflective cup 140 to generate white light, and FIG. 8B. When the red, green, and blue LEDs are arranged in one LED unit 144 as described above, the light reflected from the side of the reflective cup 140 is mixed inside the reflective cup 140 to generate white light.

The LED unit 110 may have a configuration as shown in FIG. 2, and may be formed as a hemispherical lens instead of the lens 30 shown in FIG. 2. In this case, a reflective pattern or a haze pattern is formed on the surface of the lens such that red, green, and blue straight light is not directly irradiated onto the liquid crystal display panel 102, or as shown in FIG. The cap 142 is formed of a material to shield the opening of the reflective cup 140, and a reflective pattern or a haze pattern 142a is formed on a portion of the reflective cup 140 facing the LED unit 110.

In addition, the LED unit 110 may include a heat sink for dissipating heat generated from the LED under the LED.

The LED unit 144 forms a group by a predetermined number, and as shown in FIGS. 6 and 7, the MCPCB 118 through a cable 146 connected to the LED unit 110 of the LED unit 144. Is mounted on. MCPCB 118 is a substrate formed of a metal material such as aluminum, at least one is disposed on the bottom cover 120 to supply power to the LED unit (110). For this purpose, the MCPCB 118 has a first connector 118a, and a second connector 146a connected to the cable 146 is inserted into the MCPCB connector 118a. As the cable 146, a flexible flat cable (FFC) having a very small volume and formed of a film may be used. The first connector 118a may be located on the MCPCB 118 as shown in FIGS. 6 and 7, or may be located inside the MCPCB 118 as shown in FIG. 9.

As such, the LED unit 144 of the backlight unit according to the present invention may be attached or detached to the MCPCB 118 through the cable 146 and the first and second connectors 118a and 146a, thereby providing a specific LED unit 144. Even if a defect occurs, replacement is possible, and thus a problem that the signal supplied to the other LED units 144 is blocked does not occur.

In addition, the LED unit 144 of the backlight unit according to the present invention mixes the light generated by the LED unit 110 and the light emitted from the LED unit 110 toward the liquid crystal display panel 102. The reflection cup 140 may be irradiated to reduce the luminance difference between the portion where the LED unit 110 is located and the portion where the LED unit 110 is not located. In addition, since the reflective cup 140 reflects the light from the side of the LED unit 110 to provide a space for mixing, the gap between the LED unit 110, the diffusion plate 106, and the optical sheet 104 may be reduced. Since it is not necessary to secure a large amount, the thickness of the backlight unit and the liquid crystal display using the same can be reduced.

The diffusion plate 106 serves to diffuse the light generated from the LED unit 110 to the entire surface of the liquid crystal display panel 102, and the optical sheets 104 may include at least one diffusion sheet and at least one prism sheet. Including the light, the light incident from the diffusion plate uniformly irradiates the entire liquid crystal display panel 102, and serves to condense the light toward the entire surface of the display by bending the path of the light in a direction perpendicular to the display surface.

The bottom cover 120 is manufactured in a container structure in which the liquid crystal display panel 102 and the backlight unit are supported and accommodated. The side of the bottom cover 120 is attached to the reflective sheet 112 through a double-sided tape or the like, the reflective sheet 112 is a position of the LED unit 144 on the bottom cover 120 is formed MCPCB 118 By disposing the light, the light emitted to the outside of the LED unit 144 is reflected toward the liquid crystal display panel 102.

As described above, the backlight unit and the liquid crystal display device using the same according to the present invention includes a LED unit including an LED, and a reflection cup for mixing the light generated from the LED unit and reflecting the light to the liquid crystal display panel, thereby providing color mixing. Since the gap between the optical member and the LED unit is not required to be large, the backlight unit and the liquid crystal display device using the same can be thinned.

In addition, the backlight unit and the liquid crystal display device using the same according to the present invention can easily replace the LED unit consisting of the LED unit and the reflective cup detachable to the MCPCB even if a failure occurs in a specific LED unit.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present 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 (26)

Point light source; A printed circuit board supplying driving power to the point light source through a first connector; And And a plurality of wirings, one terminal being connected to the point light source and a second connector electrically connected to the first connector, to be attached to and detached from the printed circuit board. According to claim 1, And the second connector is commonly connected to the n number of point light sources. According to claim 1, And a reflective cup assembled to the point light source such that the point light source is positioned therein. The method of claim 3, wherein And n points of light sources are located in one of the reflection cups. According to claim 1, The wiring unit is a backlight unit, characterized in that the flexible flat cable. According to claim 1, And a further optical member disposed above the light sources. According to claim 1, And a bottom cover accommodating the printed circuit board, the point light source, and the wiring. The method of claim 7, wherein And a reflective sheet having a portion except for the point light source and disposed in the bottom cover on which the printed circuit board is formed. The method of claim 3, wherein The point light source is a backlight unit, characterized in that the light emitting diode. The method of claim 9, A backlight unit, wherein any one of a red light emitting diode, a green light emitting diode, and a red light emitting diode is disposed in the reflection cup. The method of claim 9, At least one red light emitting diode, at least one green light emitting diode, and at least one blue light emitting diode are disposed in the reflection cup. The method of claim 3, wherein And the reflective cup includes a transparent cap for shielding an opening surface of the reflective cup. The method of claim 12, And a reflective pattern or a haze pattern is formed at a portion of the transparent cap that faces the position of the point light source. A liquid crystal display panel; And A printed circuit board having a point light source, a printed circuit board for supplying driving power to the point light source through a first connector, and a second connector connected to one side of the point light source and electrically connected to the first connector; And a backlight unit for irradiating light to the liquid crystal display panel by providing a plurality of wires attached to and detached from the liquid crystal display panel. The method of claim 14, And the second connector is commonly connected to the n point light sources. The method of claim 14, And the backlight unit further comprises a reflective cup assembled to the point light source such that the point light source is positioned therein. The method of claim 16, And n point light sources are positioned in one of the reflection cups. The method of claim 14, And wherein the wiring is a flexible flat cable. The method of claim 14, And the backlight unit further comprises an optical member disposed on the light sources. The method of claim 14, And the backlight unit further includes a bottom cover to accommodate the printed circuit board, the point light source, and the wiring. The method of claim 20, And the backlight unit further includes a reflective sheet having a portion except for the point light source and disposed in the bottom cover on which the printed circuit board is formed. The method of claim 16, And the point light source is a light emitting diode. The method of claim 22, And one of a red light emitting diode, a green light emitting diode, and a red light emitting diode is disposed in the reflection cup. The method of claim 22, And at least one red light emitting diode, at least one green light emitting diode, and at least one blue light emitting diode are disposed in the reflection cup. The method of claim 16, And the reflective cup comprises a transparent cap for shielding an opening of the reflective cup. The method of claim 25, And a reflective pattern or a haze pattern is formed at a portion of the transparent cap that faces the position of the point light source.

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