KR102031777B1 - Backlight unit and liquid crystal display device including the same - Google Patents

Abstract

The present invention relates to a backlight unit and a liquid crystal display device including the at least one LED package installed in the corner region of the cover bottom; It is disposed under the LED package, it characterized in that it comprises a heat diffusion for diffusing heat generated from the LED package.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE INCLUDING THE SAME}

The present invention relates to a backlight unit and a liquid crystal display device including the same. More particularly, the LED package is disposed in each corner region of the cover bottom, and each of the LED packages includes a heat diffusion unit, thereby improving reliability of the backlight unit. The present invention relates to a backlight unit capable of reducing power consumption and a liquid crystal display device including the same.

Recently, as the information society develops, the demand for the display field is increasing in various forms, and in response, various flat panel display devices, for example, liquid crystal, which have features such as thinning, light weight, and low power consumption Liquid crystal display devices, plasma display panel devices, electroluminescent display devices, and the like have been studied.

Among these, the liquid crystal display is one of the most widely used flat panel display devices, and includes a liquid crystal layer between the two substrates and the two substrates on which the pixel electrode and the common electrode are formed.

Such a liquid crystal display determines an orientation of liquid crystal molecules of a liquid crystal layer according to an electric field generated by a voltage applied to an electrode, and controls polarization of incident light to display an image.

The liquid crystal display device does not have a light emitting device, and thus a separate light source must be provided. The light source is called a backlight unit (BLU).

Here, as a light source of the backlight unit, a light emitting diode (LED) having small size, low power consumption, high reliability, and the like is widely used.

Hereinafter, a backlight unit will be described with reference to the drawings.

1 is a partial cross-sectional view of a liquid crystal display device including a general side type backlight unit, and FIG. 2 is a view illustrating an LED assembly provided in a general side type backlight unit.

As shown in FIG. 1, the liquid crystal display includes a liquid crystal panel 10, a backlight unit 20, a cover bottom 30, a top cover 50, and the like.

The liquid crystal panel 10 includes a first substrate (not shown) and a second substrate (not shown) that are bonded to each other with a liquid crystal layer (not shown) interposed therebetween.

The first polarizing plate 12 and the second polarizing plate 14 which selectively transmit only specific light are attached to the outer surfaces of the first substrate and the second substrate, respectively.

The backlight unit 20 includes a reflector 22, a light guide plate 24, a plurality of optical sheets 26, and an LED assembly 28, and serves to supply light to the liquid crystal panel 10.

As shown in FIG. 2, the LED assembly 28 is composed of a plurality of LED packages 28a and a printed circuit board 28b, and a plurality of LED packages 28a are arranged at predetermined intervals on the printed circuit board 28b. Spaced apart.

Although not shown, the LED assembly 28 may include a power supply unit (not shown) for supplying power to the plurality of LED packages 28a.

A plurality of light emitting diodes (LEDs) emit light having red (R), green (G), and blue (B) colors toward the light incident surface of the light guide plate 24, and when such RGB LEDs are turned on at once, color mixing occurs. By white light can be implemented.

At this time, the LED is a high-brightness LED, accompanied by high heat in the process of converting electrical energy into light energy, there is a problem that the efficiency of light emitted from the LED is significantly reduced when the temperature of the LED is above a certain temperature (junction temperature).

Therefore, the LED package may be mounted on a printed circuit board mainly made of metal so as to easily dissipate heat generated while driving the LED.

Referring back to FIG. 1, the reflector 22 serves to reflect the light incident from the plurality of LEDs 28a toward the liquid crystal panel 10 when it passes through the rear surface of the light guide plate 24, and the light guide plate 24 may have a plurality of light guide plates 24. The light incident from the LED 28a is totally reflected to provide a surface light source to the liquid crystal panel 10.

After the liquid crystal panel 10 and the backlight unit 20 are disposed inside the cover bottom, the cover bottom 30 and the top cover 50 are combined to complete the liquid crystal display module.

In this case, the cover bottom 30 may further include a support main body 40 having a rectangular frame shape surrounding the edges of the liquid crystal panel 10 and the backlight unit 20.

As such, in the conventional side type backlight unit, the LED assembly is combined with one inner side of the cover bottom to secure structural stability and emit heat generated while driving the LED.

And, the LED assembly is arranged on at least one side of the backlight unit 20 to make the line light source as a surface light source.

On the other hand, when using a low-output LED package, the LED assembly limits the separation distance between the LED package to reduce the occurrence of hot spots, thereby limiting the number of LED packages.

On the other hand, when using a high-output LED package, there is a problem in that the operating current must be lowered due to the limitation of thermal diffusion.

In addition, when manufacturing red, green, and blue LED chips in one LED package to manufacture a liquid crystal display device having high color purity, light output for each temperature of the red, green, and blue LEDs is Because of this difference, it is difficult to configure a single LED package.

That is, to implement a red, green, and blue LED chip in one LED package to realize a liquid crystal display device of high color purity, a separate light output control device may be provided or a heat dissipation structure may be used. Needs improvement.

The present invention is to solve the above problems, by arranging the LED package in each corner area of the cover bottom, and each of the LED package has a heat diffusion portion can improve the reliability of the backlight unit and reduce the power consumption. An object of the present invention is to provide a backlight unit and a liquid crystal display device including the same.

Another object of the present invention is to provide a backlight unit and a liquid crystal display including the same, which individually drive RGB chips of an LED package having an edge array structure to improve color purity by implementing color separation.

In order to achieve the above object, the backlight unit includes: at least one LED package installed at an edge region of the cover bottom; A heat spreader disposed under the LED package and diffusing heat generated from the LED package; As the incident light from the LED package is totally reflected, it characterized in that it comprises a light guide plate to uniformly diffuse the incident light to provide a surface light source.

Here, the LED package may include at least one LED chip.

The at least one LED chip may be a red chip, a green chip, or a blue chip.

The heat diffusion part may include a first diffusion substrate in contact with the LED package and a second diffusion substrate in contact with the cover bottom, and a plurality of semiconductor electrodes formed between the first and second diffusion substrates.

In this case, the heat diffusion part may absorb heat from the first diffusion substrate and release heat to the second diffusion substrate as voltage is applied to the plurality of semiconductor electrodes.

The light guide plate may further include a light guide plate configured to diffuse the incident light evenly as the incident light from the LED package is totally reflected to provide a surface light source.

In this case, the light guide plate may have a rectangular shape or an octagonal shape.

A liquid crystal display device for achieving the above object, the liquid crystal display device comprising a backlight unit for supplying light to the liquid crystal panel, wherein the backlight unit is at least at the corners of the cover bottom, the cover bottom One LED package, characterized in that it comprises a heat spreader disposed below the LED package to diffuse the heat generated from the LED package.

The LED package may include a red chip, a green chip, and a blue chip.

As the red chip, the green chip, and the blue chip are sequentially driven, color division driving is preferable.

The heat diffusion part may include a first diffusion substrate in contact with the LED package and a second diffusion substrate in contact with the cover bottom, and a plurality of semiconductor electrodes formed between the first and second diffusion substrates.

In this case, the heat diffusion part may absorb heat from the first diffusion substrate and release heat to the second diffusion substrate as voltage is applied through the plurality of semiconductor electrodes.

As described above, in the backlight unit and the liquid crystal display including the same according to the present invention, the LED package is disposed in each corner region of the cover bottom, and each of the LED packages includes a heat diffusion unit, so that the color performance and reliability of the backlight unit can be improved. Can improve.

In addition, color purity of the LCD may be improved by driving color division of the backlight unit.

In addition, the number of LED packages may be reduced to reduce power consumption of the backlight unit.

1 is a cross-sectional view of a liquid crystal display device including a general side type backlight unit.
2 is a view illustrating an LED assembly provided in a general side type backlight unit.
3 is a cross-sectional view of an LCD including a backlight unit according to an exemplary embodiment of the present invention.
4 is a view schematically showing a light source unit according to an embodiment of the present invention.
5 is a view referred to explain the arrangement position of the light source unit in the backlight unit according to the embodiment of the present invention.
6 is a diagram showing an arrangement of a light source unit according to the first embodiment of the present invention.
7 is a diagram showing an arrangement of a light source unit according to a second embodiment of the present invention.
8 is a diagram showing an arrangement of a light source unit according to a third embodiment of the present invention.
9 is a diagram showing an arrangement of a light source unit according to a fourth embodiment of the present invention.

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

3 is a cross-sectional view of a liquid crystal display including a backlight unit according to an exemplary embodiment of the present invention, and FIG. 4 is a schematic view of a light source unit according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the liquid crystal display according to the present invention includes a liquid crystal panel 110, a backlight unit 120, a cover bottom 130, a top cover 150, and the like.

The liquid crystal panel 110 includes a first substrate (not shown) and a second substrate (not shown) which are bonded to each other with a liquid crystal layer (not shown) interposed therebetween.

In this case, the area of one edge of the first substrate is larger than that of the second substrate, and a drive for applying signals to a plurality of gate wires (not shown) and data wires (not shown) on one edge of the first substrate. Circuit portions can be formed.

In the first substrate, the pixel region Pixel may be defined by crossing a plurality of gate lines and data lines.

In addition, a thin film transistor, which is a switching element, is provided in each pixel region so as to be connected to the pixel electrode (not shown) in one-to-one correspondence.

In the second substrate, a black matrix (not shown) may be formed to cover non-display elements such as a gate line, a data line, and a thin film transistor, and a common electrode (not shown) may be formed to cover the black matrix. .

The first polarizing plate 112 and the second polarizing plate 114 selectively transmitting only specific light may be attached to the outer surfaces of the first substrate and the second substrate, respectively.

In general, a color filter layer including red, green, and blue color filter patterns (not shown) corresponding to red, green, and blue pixel areas (not shown) is formed on the second substrate.

However, in the second substrate of the liquid crystal display according to the present invention, the color filter layer including the red, green, and blue color filter patterns (not shown) may be removed by dividing each color by using the high output LED package. .

The backlight unit 120 includes a reflector 122, a light guide plate 124, a plurality of optical sheets 126, a light source unit, and supplies light to the liquid crystal panel 110.

The reflector 122 serves to reflect toward the liquid crystal panel 110 when light incident from the LED package 128 passes through the rear surface of the light guide plate 124.

That is, the reflector plate 122 uses a plate having a high light reflectance, and when the light incident from the LED package 128 passes through the rear surface of the light guide plate 124, the reflector 122 reflects toward the liquid crystal panel 110 to improve the brightness of the light. Can be.

The light guide plate 124 serves to provide a surface light source to the liquid crystal panel 110 by total reflection of the light incident from the plurality of LED packages 128.

In this case, the light guide plate 124 may have various shapes as the LED package 128 is disposed in the corner region of the cover bottom 130.

For example, the light guide plate 124 may have a rectangular shape or an octagonal shape.

In addition, a pattern of a specific shape may be formed in the light guide plate 124 to supply a uniform surface light source to the liquid crystal panel 110.

In this case, the light source unit serves to supply light to the light guide plate 124, and includes an LED package 128 and a heat diffusion unit 129.

The LED package 128 may be disposed in at least one corner area of the cover bottom, and may be a high output LED package including a red chip, a green chip, a blue chip, and the like. .

LEDs are high-brightness LEDs, which are accompanied by high heat in the process of converting electrical energy into light energy, and there is a problem in that the efficiency of light emitted from the LEDs is significantly lowered when the temperature of the LED is higher than a certain temperature.

Therefore, in the related art, an LED assembly having a form in which an LED is mounted on a printed circuit board mainly made of metal is used mainly to easily dissipate heat generated while driving an LED.

However, when using the LED assembly, when using a low output LED package, there was a limit in reducing the number of LED packages due to hot spots, whereas in the case of using a high output LED package, the degree of heat diffusion of the LED package Due to the limitation, there was a problem in that the use current must be lowered.

Therefore, in the present invention, the number of LED packages is reduced by using a high output LED package, and the heat spreader 129 is disposed under each LED package 128 to improve the heat diffusion degree of the LED package.

As shown in the drawing, the light source unit may be disposed in the stepped area AA where a step is formed on the side surface of the cover bottom 130.

For example, the stepped area AA may be elongated along the side surface of the cover bottom 130 or may be partially formed only at an edge area of the cover bottom 130.

When the liquid crystal panel 110 and the backlight unit 120 are disposed inside the cover bottom 130, the cover bottom 130 and the top cover 150 are combined to complete the liquid crystal display module.

Hereinafter will be described in detail with respect to the LED package and the heat diffusion unit which is a light source.

As shown in FIG. 4, the light source unit according to the present invention includes an LED package 128 and a heat spreader 129.

The heat diffusion part 129 according to the present invention includes a first diffusion substrate 129a, a second diffusion substrate 129b, and a plurality of semiconductor electrodes 129c, and diffuses heat generated from the LED package 128. Play a role.

In this case, the first diffusion substrate 129a and the second diffusion substrate 129b may be, for example, a substrate made of a ceramic material as an insulator.

In addition, the plurality of semiconductor electrodes 129c may include an N type semiconductor electrode and a P type semiconductor electrode.

Although not shown, a metal substrate, which is a conductor, may be formed between the first diffusion substrate 129a, the second diffusion substrate 129b, and the plurality of semiconductor electrodes 129c, respectively.

The heat spreader 129 may be, for example, a Peltier device.

In this case, the heat diffusion unit 129 may be attached between the LED package 128 and the cover bottom 130 by an adhesive resin, for example, the first diffusion substrate 129a of the heat diffusion unit 129 is The LED package 128 may be attached to the LED package 128 by an adhesive resin, and the second diffusion substrate 129b of the heat diffusion unit 129 may be attached to the cover bottom 130 by the adhesive resin.

Referring to the heat diffusion process of the heat diffusion unit 129, first, electrons move from the N-type semiconductor electrode to the P-type semiconductor electrode as voltage is applied to the plurality of semiconductor electrodes through the power supply unit.

Due to the movement of electrons, a potential difference occurs between the N-type semiconductor electrode and the P-type semiconductor electrode.

In this case, the voltage transmitted to the heat diffusion unit 129 may be a voltage such that a potential difference is generated between the N type semiconductor electrode and the P type semiconductor electrode by causing electrons to move from the N type semiconductor electrode.

Next, the electrons of the N-type semiconductor electrode are moved to the P-type semiconductor electrode by the generated potential difference, wherein the electrons are transferred to the second diffusion substrate 129b by using the heat energy absorbed from the first diffusion substrate 129a. To the side.

Similarly, holes of the P-type semiconductor electrode are moved toward the second diffusion substrate 129b by using the heat energy absorbed from the first diffusion substrate 129a.

At this time, the first diffusion substrate 129a is in a state of having high thermal energy as it is first heated due to heat generated from the LED package 128.

However, as the electrons of the N-type semiconductor electrode and the holes of the P-type semiconductor electrode absorb and move the heat energy of the first diffusion substrate 129a, the heat energy of the first diffusion substrate 129a is transferred to the second diffusion substrate 129b. Will be.

By such a process, heat generated in the LED package 128 is transferred to the cover bottom 130 through the heat spreader 129, thereby lowering the temperature of the LED package 128.

Therefore, the backlight unit 120 according to the present invention includes arranging at least one LED package 128 in the corner region of the cover bottom 130 and providing the heat spreader 129 under the LED package 128. Accordingly, the temperature under the LED package 128 may be kept constant, thereby improving color performance and reliability of the backlight unit.

On the other hand, the backlight unit 120 according to the present invention can improve the color purity of the liquid crystal display by driving color division.

When the red chip, the green chip, and the blue chip of the LED package 128 are driven at the same time, a white screen is displayed. At this time, the lower portion of the high output LED package 128 has a heat spreader 129. ), The temperature is kept constant so that no color change occurs with temperature.

Even though the red, green, and blue chips of the LED package 128 are sequentially driven for several tens of Hz, the human eye is recognized as white and synchronized with the liquid crystal panel 110. In this case, the noise of the color spectrum can be slowed down to increase the color purity of the liquid crystal display.

In addition, the red, green, and blue chips of the LED package 128 are individually driven to enable red, green, and blue color filter patterns (not shown) on the second substrate of the LCD. The color filter layer including) may be removed.

At this time, the divided driving method for each color is, for example, a driving method sequentially (clockwise or counterclockwise) for each LED package 128 disposed at each corner region, or the same color in all LED packages 128. It may be a driving scheme for operating the LED chip and sequentially operating LED chips of different colors.

That is, the backlight unit 120 according to the present invention uses the color division driving to individually drive the red chip, the green chip, and the blue chip of the LED package 128. Purity can be improved.

5 is a view referred to explain the arrangement position of the light source unit in the backlight unit according to the embodiment of the present invention, FIG. 6 is a view showing the arrangement of the light source unit according to the first embodiment of the present invention, and FIG. FIG. 8 is a view showing the arrangement of a light source unit according to the second embodiment of the present invention, and FIG. 8 is a view showing the arrangement of a light source unit according to the third embodiment of the present invention, and FIG. 9 is a fourth embodiment of the present invention. It is a figure which shows the arrangement of the light source part.

As shown in FIG. 5, the light source unit in the backlight unit according to the present invention may be disposed in the corner areas A to D of the cover bottom (130 of FIG. 3).

As such, it is necessary to look at the relationship with the light guide plate 124 in order for the light source unit to be disposed at the corner areas A to D of the cover bottom (130 of FIG. 3).

First, as shown in FIG. 6, the LED package 128 of the light source unit according to the first embodiment of the present invention may be disposed to emit light in a vertical direction (vertical direction) of the light guide plate 124.

Here, although not shown, the heat diffusion unit 129 of FIG. 3 may have the same rectangular shape as that of the LED package 128.

That is, each LED package 128 may be disposed to be spaced apart by 'W1' in a vertical direction (vertical direction), and spaced apart by about 'W2' in a horizontal direction (horizontal direction).

In this case, a pattern of a specific shape may be formed in the light guide plate 124 (particularly, the light incident part of the light guide plate) to supply a uniform surface light source to the liquid crystal panel.

Next, as shown in FIG. 7, the LED package 128 of the light source unit according to the second embodiment of the present invention may be arranged to emit light in the horizontal direction (horizontal direction) of the light guide plate 124.

In this case, each LED package 128 may be disposed to be spaced apart by about 'W1' in a vertical direction (vertical direction) and spaced apart by 'W2' in a horizontal direction (horizontal direction).

In this case, a pattern of a specific shape may be formed in the light guide plate 124 (particularly, the light incident part of the light guide plate) to supply a uniform surface light source to the liquid crystal panel.

Next, as shown in FIG. 8, the LED package 128 of the light source unit according to the third embodiment of the present invention is a triangle so that it can be disposed in the corner areas (A to D) of the cover bottom (130 of FIG. 3) The light guide plate 124 may be formed in a shape so as to emit light in a diagonal direction of the LGP 124.

Although not shown, the heat diffusion unit 129 of FIG. 3 may have the same triangular shape as that of the LED package 128.

The light guide plate 124 may be an octagonal shape including a first side of the 'W1' length, a second side of the 'W2' length, and a third side of the 'W3' length to be suitable for the triangular LED package 128. Can be.

In addition, as shown in FIG. 9, the LED package 128 of the light source unit according to the fourth embodiment of the present invention has a circular shape so that the LED package 128 may be disposed in the corner areas A to D of the cover bottom (130 of FIG. 3). The light guide plate 124 may be disposed to emit light in a diagonal direction of the light guide plate 124.

In this case, the heat diffusion unit 129 may have the same circular shape as that of the LED package 128.

In addition, the light guide plate 124 may be a figure including a curved line having a first side of the 'W1' length, a second side of the 'W2' length, and a 'W3' length to suit the circular LED package 128.

In the liquid crystal display according to the present invention, the shape of the light guide plate, the LED package, and the heat spreader is not limited to the above embodiments, and may be implemented in various forms in which the LED package may be disposed in the corner region of the cover bottom.

As described above, the liquid crystal display according to the present invention may arrange LED packages at respective corner regions of the cover bottom and provide heat diffusion parts to the LED packages, thereby improving color performance and reliability of the backlight unit.

In addition, color purity of the LCD may be improved by driving color division of the backlight unit.

In addition, the number of LED packages may be reduced to reduce power consumption of the backlight unit.

The embodiments of the present invention as described above are merely exemplary, and those skilled in the art may freely modify the present invention without departing from the gist of the present invention. Therefore, the protection scope of the present invention shall include modifications of the present invention within the scope of the appended claims and equivalents thereof.

110: liquid crystal panel 122: reflective sheet
124: light guide plate 128: LED package
129: heat diffusion unit 120: backlight unit
130: Cover Bottom 150: Top Cover

Claims (14)

At least one LED package emitting light;
Disposed under the LED package to diffuse heat generated from the LED package, and formed between the first diffusion substrate in contact with the LED package and the second diffusion substrate in contact with the cover bottom and the first and second diffusion substrates A heat diffusion part including a plurality of semiconductor electrodes;
And a light guide plate that totally reflects incident light from the LED package and outputs the light to a surface light source.
The method of claim 1,
And the LED package includes at least one LED chip.
The method of claim 2,
And the at least one LED chip is a red chip, a green chip, or a blue chip.
The backlight unit of claim 1, wherein the LED package is disposed at at least one corner of four corners of the light guide plate.
The method of claim 1,
The heat diffusion unit absorbs heat from the first diffusion substrate and emits heat to the second diffusion substrate as voltage is applied to the plurality of semiconductor electrodes.
The method of claim 1,
The light guide plate may have a rectangular shape or an octagonal shape.
A liquid crystal panel which displays an image;
At least one LED package for emitting light and supplying the light to the liquid crystal panel;
A cover bottom in which the LED package is disposed;
Disposed under the LED package to diffuse heat generated from the LED package, and between a first diffusion substrate in contact with the LED package, a second diffusion substrate in contact with the cover bottom, and the first and second diffusion substrates. A heat diffusion part including a plurality of semiconductor electrodes formed;
And a light guide plate that totally reflects incident light from the LED package and outputs the light to a surface light source.
The method of claim 7, wherein
The LED package includes a red chip, a green chip, and a blue chip.
The method of claim 8,
And a color-dividing driving device as the red chip, the green chip, and the blue chip are sequentially driven.
The liquid crystal display of claim 7, wherein the LED package is disposed at at least one corner of four corners of the light guide plate.
The method of claim 7, wherein
And the heat diffusion unit absorbs heat from the first diffusion substrate and emits heat to the second diffusion substrate as voltage is applied through the plurality of semiconductor electrodes.
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