KR20060114545A - Back light unit having multi-chip light emitting diode package and display system - Google Patents

Abstract

An edge light type backlight unit and a display device adopting the same are provided to eliminate the need of a space for mixing color lights, thereby reducing the thickness of the backlight unit, by mixing the color lights within a light emitting diode package having multiple light emitting diodes. An edge light type backlight unit comprises a light guiding plate and a light source unit(60). The light guiding plate guides the light to a display panel for forming an image. The light source unit is disposed on at least one surface of the light guiding plate. The light source unit is formed by mounting a plurality of multi-chip light emitting diode packages(70) on a printed circuit board(65). Each of the multi-chip light emitting diodes packages light emitting diodes(70a,70b,70c), which emit the light having at least two wavelength regions.

Description

Photometric backlight unit having a multi-chip light emitting diode package and a display device employing the same {Back light unit having multi-chip light emitting diode package and display system}

1A illustrates a conventional direct type backlight unit.

1B illustrates a photometric backlight unit using a CCFL as a light source.

2 illustrates a photometric backlight unit using a light source packaged with a single light emitting diode chip.

3 illustrates a photometric backlight unit having a light emitting diode as a light source and having a dummy light guide plate in the related art.

4A schematically illustrates a display device employing a photometric backlight unit according to a preferred embodiment of the present invention.

4B illustrates a light source unit provided in the photometric backlight unit according to the present invention.

Figure 5a shows a plan view of a multi-chip light emitting diode unit used in the photometric backlight unit according to the present invention.

5B is a cross-sectional view taken along the line A-A of FIG. 5A.

FIG. 6A illustrates light rays that are mixed and emitted with a wide direct angle in the multi-chip LED unit according to the present invention.

FIG. 6B illustrates light rays emitted from a light source conventionally comprised of a single light emitting diode chip for comparison with FIG. 6A.

FIG. 7 illustrates in detail the light source units in which the multi-chip LED unit illustrated in FIG. 5A is disposed in a line on a printed circuit board.

Fig. 8 (a) is a plan view of another example multi-chip light emitting diode unit used in the backlight unit according to the present invention, Fig. 8 (b) is a side cross-sectional view thereof, and Fig. 8 (c) is a front sectional view.

9 illustrates an embodiment in which a heat dissipation structure is coupled to a backlight unit according to the present invention.

10A illustrates another embodiment in which a heat dissipation structure is coupled to a backlight unit according to the present invention.

10B is a cross-sectional view taken along the line B-B in FIG. 10A.

FIG. 11 shows a modification of the metal block shown in FIG. 9.

12 is a front view of another embodiment in which a heat dissipation structure is coupled to a backlight unit according to the present invention.

<Explanation of symbols for the main parts of the drawings>

60 ... light source, 65 ... printed circuit board

70,70 ', 70 "... Multi-Chip LED Package

70a, 70b, 70c, 91a, 91b, 91c, 91d, 101a, 101b, 101c, 101d ... light emitting diode chip

93,104 ... cup, 93,107 ...

97,102a, 102b, 102c ... Chip Bonding Pad, 95,106 ... Heat Resistant Extension Pad

110 ... metal block, 112 ...

120 ... metal chassis, 125,143a, 143b ... heat pipe

130,141a, 141b, 145a, 145b ... heat sink, 150 ... color sensor

The present invention relates to a light-emitting backlight unit having a light emitting diode package packaged with a light emitting chip of a plurality of wavelengths, and a display device employing the light-emitting diode. More particularly, the light-emitting backlight having excellent color reproducibility and miniaturization by minimizing its thickness A unit and a display device employing the same.

A liquid crystal display device, which is a kind of light-receiving flat panel display used in notebooks, desktop computers, LCD-TVs, mobile communication terminals, etc., does not have its own light emitting capability, and thus forms an image by selectively transmitting illumination light emitted from the outside. To this end, a backlight unit for illuminating light is provided on the back of the liquid crystal display.

The backlight unit is classified into a direct light type and an edge light type according to the arrangement of the light sources. The direct type is a method in which a lamp installed directly below the liquid crystal panel directly irradiates light directly onto the liquid crystal panel.

Referring to FIG. 1A, the direct type backlight unit is a means for uniformly injecting the light emitted from the LED 1 and the LED 1 into the liquid crystal panel 10. And a reflecting plate 2 for reflecting light emitted from the LED 1 toward the liquid crystal panel 10 below the LED 1. A prism sheet 7 is disposed between the diffusion sheet 5 and the liquid crystal panel 10 to correct the light propagation path so that the light is directed toward the liquid crystal panel 10.

 On the other hand, referring to FIG. 1B, the light metering type is a method in which a lamp installed at a side of a light guide panel (LGP) irradiates light and transmits the irradiated light to the liquid crystal panel through the light guide plate.

The direct type has a disadvantage of being thick because a sufficient separation distance b between the light source and the diffuser plate is required to suppress hot spots and to improve uniformity of luminance distribution. On the other hand, the photometric type has a relatively thin thickness compared to the direct type because the light source is disposed on the side.

The direct type is suitable for large displays of 30 inches or more, such as LCD TVs, because the light source can be freely and effectively placed in a large area. The metering type is a small and medium size display used for a monitor or a mobile phone because the light source is placed in a limited position on the side of the light guide plate. Suitable for The present invention improves the structure of the photometric backlight for thinning.

Referring to FIG. 1B, Cold Cathode Fluorescent Lamps (CCFLs) are provided on both edges of the LGP 20. In addition, a reflecting plate 29 for emitting light incident from the CCFL 22 toward the liquid crystal panel 23 is formed on the bottom surface of the light guide plate 20. Therefore, the light irradiated from the CCFL 22 is incident to the light guide plate 20 through the side surface. The incident light is converted into surface light by the light guide plate 20 and the reflecting plate 29 and is emitted to the upper surface of the light guide plate 20.

The diffusion plate 25 and the optical prism sheet 27 are disposed on the upper surface of the light guide plate 20. Accordingly, the light emitted to the upper surface of the light guide plate 20 is diffused by the diffusion plate 25 and travels toward the liquid crystal panel 23 with the path corrected by the optical prism sheet 27. .

The CCFL 22 has an advantage of uniformly irradiating white light because the CCFL 22 is disposed almost coincident with the side surface of the light guide plate. However, when the CCFL 22 is applied to a large-area display, one CCFL is insufficient in light quantity, and thus, two or more CCFLs must be stacked in order to achieve sufficient luminance. In addition, since the CCFL 22 uses mercury as a discharge gas, the CCFL 22 cannot be free from environmental problems, and is operated by a high frequency AC signal and has a narrow operating temperature range.

 On the other hand, as a light source replacing the above-described CCFL, a light emitting unit using a light emitting diode (LED) is emerging. Unlike the CCFL, which is a linear light source, the light emitting diode is a point light source, and has the advantages of longer life, wider operating temperature range, faster response speed, environmental friendliness, and high color reproducibility than the CCFL. In addition, there is an advantage that it is possible to illuminate the light of a high luminance depending on the structure.

When the LED is used as a light source of the photometric backlight unit, as shown in FIG. 2, a red LED (LR), a green LED (LG), and a blue LED (LB) are regularly arranged, and the red light emitted from each of these LEDs, Green light and blue light are mixed to make white light. Therefore, since a space for mixing each color light is required, the separation distance between the light guide plate and the light source is large, thereby increasing the size of the backlight unit. If the space necessary for mixing is not secured enough, the light line and the dark part increase due to the uneven distribution of colors in the light guide plate. Furthermore, a problem arises in that the border space of the effective screen of the display becomes large to cover the bright lines and the dark portions.

On the other hand, side view type LEDs are generally mounted with the side of the package as a mounting surface. In the case of the side mounting type, the heat dissipation efficiency is low due to a long heat dissipation path. Therefore, the side emitting type LED is mainly applied to a small LCD in which luminance is satisfied with a relatively small amount of light by low current driving in order to minimize heat generation. However, medium sized LCDs have to use high-capacity LEDs capable of operating at high currents to meet the required luminance, and the number of LEDs must be increased. Since high heat is generated when high current is used, the side emitting type LED is not suitable as an LED for a medium LCD.

Meanwhile, as shown in FIG. 3, a dummy light guide plate 33 for color mixing is separately provided in the lower portion of the main light guide plate 30 to reduce the separation distance for mixing color, and disposed on the side of the dummy light guide plate 33. There is an example in which light is emitted from an LED 35 made of a single chip. In such a structure, there is still a problem that the demand for thinning is not satisfied due to the increase in the overall thickness due to the dummy light guide plate 33.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a light-emitting backlight unit having a multi-chip light emitting diode package capable of compacting by reducing mixed color space and a display device employing the same.

Still another object of the present invention is to provide a light-emitting backlight unit and a display device employing the same, which are capable of efficiently dissipating heat generated from a light emitting diode package.

In order to achieve the above object, a light-emitting backlight unit according to the present invention includes a light guide plate for directing light to a display panel for forming an image; And a light source unit mounted on a printed circuit board so that the multi-chip LED packages packaged with the LED chip emitting light of at least two wavelength regions are disposed on the printed circuit board so as to be perpendicular to the LGP. It features.

In order to achieve the above object, the light-emitting backlight unit according to the present invention includes a light guide plate having a square shape and an area that is the same as or similar to that of a liquid crystal panel at a lower portion of the liquid crystal panel, and directs the light from the side of the light guide plate. In a side-lit backlight unit for irradiating, a multi-chip LED package including at least three LED chips emitting at least red light, green light and blue light in one light emitting window is a printed circuit having the rear surface of the light emitting window as a mounting surface. It includes a light source unit formed in a module arranged in a line of four or more on the substrate, characterized in that the light source unit is disposed at a distance of less than 5mm in parallel to the side of the light guide plate.

 The light emitting diode packages may be arranged in a line on at least one surface of the light guide plate in the same direction as the light emitting diode chips arranged in a line.

The light emitting diode package preferably has a rectangular light emitting window having a long length in the direction in which the light emitting diode chips are arranged in a line.

The multi-chip LED package may include a first LED chip emitting red light, a second LED chip emitting green light, a third LED chip, and a fourth LED chip emitting blue light. .

The wavelength of the green light emitted from the second LED chip and the third LED chip preferably has a difference in the range of 15-40 nm.

The multi-chip LED package includes a first LED chip emitting red light, a second LED chip emitting green light, and a third LED chip emitting blue light, wherein the second LED chip is a first LED chip. And a larger chip than the third light emitting diode chip.

In order to achieve the above object, a light-emitting backlight unit according to the present invention includes a light guide plate for directing light to a display panel for forming an image; A light source unit mounted on a printed circuit board so that the multi-chip LED package packaged with the LED chip emitting light of at least two wavelength regions is disposed on the printed circuit board so as to face the light guide plate; And a first heat sink positioned on rear surfaces of the upper light source unit and the lower light source unit, respectively.

In order to achieve the above object, a display apparatus according to the present invention, a display panel for forming an image; A light guide plate for directing light to a display panel for forming an image; And a light source unit mounted on a printed circuit board so that the multi-chip LED packages packaged with the LED chip emitting light of at least two wavelength regions are disposed on the printed circuit board so as to be perpendicular to the LGP. It features.

Hereinafter, a light-emitting backlight unit having a multi-chip LED package according to a preferred embodiment of the present invention and a display device employing the same will be described in detail with reference to the accompanying drawings.

The display device employing the photometric backlight unit according to the present invention includes a display panel 80 for forming an image, a light guide plate 50 for guiding light toward the display panel 80, as shown in FIG. And a light source unit 60 disposed on at least one surface of the light guide plate 50. In addition, a diffusion sheet 72 for diffusing light emitted from the light guide plate 50 between the light guide plate 50 and the display panel 80, and a vertical prism sheet for correcting a path of light passing through the diffusion sheet 72. 74, and a horizontal prism sheet 76 is provided. The rear surface of the light guide plate 50 is provided with a reflective sheet 55 to reflect light emitted from the light guide plate 50 toward the reflective sheet 55 toward the display panel 80 to improve the light efficiency.

The display panel 80 may be, for example, a liquid crystal panel. As shown in FIG. 4B, the light source unit 60 includes the multi-chip LED package 70 arranged in a line on the printed circuit board 65. The light source unit 60 may be disposed on one surface of the light guide plate 50 or on two opposite surfaces. That is, it may be disposed on two opposite sides or upper and lower surfaces. Alternatively, it may be disposed on two adjacent surfaces. In order to reduce the thickness of the backlight unit, it is preferable to arrange the multi-chip LED package 70 in a row.

The multi-chip LED package 70 is composed of a plurality of LED chips emitting light of at least two wavelength bands in one package. For example, the multi-chip LED package 70 may include a first LED chip 70a emitting red light, a second LED chip 70b emitting green light, and a third LED chip emitting blue light ( 70c). The first, second and third light emitting diode chips 70a, 70b and 70c are preferably arranged in a line so that they are emitted with a larger angle of directivity when light is emitted from the package. The LED packages 70 configured as described above are preferably arranged in a line on at least one surface of the LGP in the same direction as the length direction in which the LED chips are arranged.

The circuit connection between neighboring packages can easily control the range of color temperature due to the red / green / blue mixed color by having three independent lines by connecting chips of the same color in series. In this case, a series connection is preferable for driving equal forward currents for chips of the same color despite the difference in the forward voltage inherent in each chip.

In the present invention, the plurality of light emitting diode chips are configured as one package so that each color light is mixed and emitted as white light in the package. As a result, the space for mixing colors can be greatly reduced, which is very advantageous for slimming and compacting the backlight unit. In particular, the distance between the multi-chip LED package 70 and the light guide plate 50 may be 5 mm or less.

On the other hand, the second light emitting diode chip 70b that emits green light is required to supply more current than the other chips because more light is required than light of other wavelengths to realize white color by additive mixing. Here, it is preferable that the second LED chip is larger than the other chips in order to equalize the life of the second LED chip and other chips in consideration of the decrease in life as the amount of current supplied increases.

FIG. 5A illustrates another example of a multi-chip LED package 70 ′, and FIG. 5B is a cross-sectional view taken along line AA of FIG. 5A and includes first, second, third and fourth portions of one chip bonding pad 97. The light emitting diode chips 91a, 91b, 91c, and 91d are arranged in a row, and three or more pairs of terminals 98a, 98b, and 98c are provided to be insulated from the chip bonding pad 97. The three or more pairs of terminals 98a, 98b and 98c are configured by pairing a positive terminal and a negative terminal which are disposed to face each other with the chip bonding pad 97 interposed therebetween. In addition, a heat dissipation extension pad 99 extending from both sides of the chip bonding pad 97 to dissipate heat generated from the chips is provided. The heat dissipation extension pad 99 preferably has a larger width than the chip bonding pad 97.

As shown in FIG. 5B, a body 95 made of a plastic resin having a cup 93 is formed around the first to fourth LED chips 91a, 91b, 91c, and 91d. The first to fourth LED chips 91a, 91b, 91c, and 91d are disposed on the chip bonding pads 97 forming a bottom surface of the cup 93, and the inside of the cup 93 It consists of a light emitting window 94 filled with a transparent material through which light emitted from the chips can be transmitted. The light emitting window 94 is formed in a rectangular shape having a long length in the direction in which the LED chips are arranged in a line.

For example, the first LED chip 91a emits red light, the second LED chip 91b emits first green light, and the third LED chip 91c emits second green light. The fourth LED chip 91d emits blue light. The second and third LED chips 91b and 91c may be configured as chips that emit the same green light in order to match green light, which requires a relatively higher amount of light than other color lights, to a similar applied current as other color lights. . Alternatively, in order to widen the color gamut, it is possible to configure the wavelength range of the first green light and the second green light differently. The wavelength difference between the first green light and the second green light may be within the range of 15-40 nm.

More specifically, the experimental results for the 24-inch backlight unit according to the present invention will be described.

On the backlight unit, the light ratio of the red / green / blue light emitting diode chip to achieve the target color coordinates x = 0.28 and y = 0.28 (based on CIE color indicator, 1976) was derived to be 5.5: 14: 1. The applied LED chip was driven with a current ratio of 0.78: 1.75: 1. Therefore, when applying a 1-watt high-power LED chip with a maximum rating forward current of 350 mA, a 350 mA current must flow through the green chip and a 200 mA flow through the blue chip. do. In addition, a current of 706 mA must be applied to the entire package. Two problems can be derived from this. First, since the green chip has a higher load than the red chip or the blue chip, the life imbalance is generated accordingly. Second, the heat dissipation medium that can be added to the package within the limited space is limited, so that the temperature of the LED chip can exceed 125 ° C, the junction temperature (Tj) of the maximum rating, which cannot guarantee safe use. will be.

The solution to this problem is to apply the green chip as a larger chip or divide the load by configuring two chips. In addition, when the chip surface temperature is about 80 to 100 ° C, it is an economical level that guarantees the reliability of the commercialization level at least. Therefore, the number of arrayed packages of the light source unit must be increased to greatly reduce the applied current per package and compensate for the luminance. If the current flowing in one chip is flowed in parallel or in series on the same two chips, the amount of heat generated is small and the amount of light and power consumption can be gained.

Therefore, when the red, green, and blue tricolor LED chips are included in one package, one red chip, two green chips, and one blue chip are included, and the current applied to each LED chip is rated at 70%. It is preferable to limit it to% or less. In particular, lower current drive than rated can mitigate the lifespan differences associated with load differences due to inherent forward voltage differences between two green chips when two green chips are connected in parallel in a package.

Furthermore, when the first and second green chips having different wavelengths are provided in one package, the color reproducibility may be increased in addition to the effects of satisfying light quantity, load balancing, and heat dissipation.

On the other hand, the light emitting diode chip is a horizontal type that requires both wire bonding by placing both electrodes of the anode and the cathode on one plane on the non-conductive substrate according to the arrangement of the electrodes, and the electrodes are divided into the upper and lower portions of the conductive substrate At least one wire bonding on the top surface is classified as vertical. The LED package illustrated in FIG. 5A is configured to mount a horizontal LED chip. Compared to conventionally provided with a mixture of LEDs emitting red light, LEDs emitting blue light, and LEDs emitting green light, the present invention provides light of different wavelengths so that space for mixing in the light guide plate is not required separately. For example, chips emitting red light, blue light and green light are mounted in one package and emitted through one light emitting window. In this case, the distance between the light emitting diode chips is preferably as small as possible. In order to emit light with a wider directivity, the light emitting diode chips are arranged in a row, and the light emitting window 94 is formed to be long in the direction in which the light emitting diode chips are arranged. It is preferable. The light emitting window 94 may be formed to have a rectangular shape, for example.

FIG. 6A shows that the multi-chip LED package is mixed within the multi-chip LED package and is emitted with a wide directivity out of the light emitting window. FIG. 6B is conventionally a single chip LED package (LR) (LG). The light emitted from LB becomes mixed outside the package, and the direction angle is relatively small.

FIG. 7 illustrates a structure in which the multi-chip LED package 70 ′ shown in FIG. 5A is arranged in a line on the printed circuit board 65. The printed circuit board 65 may have a size substantially equal to the width and length of the side surface of the light guide plate 50. The spacing of the packages on the printed circuit board 65 is determined by the depth of the dark portion at the light inlet of the light guide plate, but in practice, the development of the design technique of the light scattering pattern of the light guide plate rather than achieving the target luminance of the entire backlight. It is determined by the number of packages needed in order. The larger the size is, the longer the light propagation distance is, so a high power light emitting diode chip is required, and the number of packages is required to be increased in accordance with the demand for high luminance. In addition, the power consumption, the degree of heat generation of the package, the balance of the light ratio of the red / green / blue light emitting diode chip for a suitable white color temperature, and the load difference of each of the three colors of the light emitting diode chip is further considered.

The first light emitting diode chips 91a are connected in series, the fourth light emitting diode chips 91d are connected in series, and the second and third light emitting diode chips 91b and 91c connected in parallel to each other are driven in series. . Here, an imbalance in the incoming forward current may occur due to the difference in the forward voltage inherent to the second and third LED chips 91b and 91c connected in parallel. Due to this imbalance, it is desirable to limit the load per chip to 70% or less of the rated power consumption to minimize the difference in load between the two chips.

FIG. 8 illustrates a package 70 " configured by dividing the chip bonding pads into three so that the LED chips of each color light are driven independently when the vertical LED chip is applied. Is a plan view of the package, Figure 8 (b) shows a side cross-sectional view, Figure 8 (c) shows a side cross-sectional view.

The package 70 "includes a body 105 having a cup 104 therein and a chip bonding pad. First, second and third chip bonding insulated from each other on the bottom surface of the cup 104. Pads 102a, 102b, and 102c are disposed, and the first light emitting diode chip 101a is disposed on the first chip bonding pad 102a, and the second and third light emitting diodes are disposed on the second chip bonding pad 102b. The diode chip 101b or 101c is disposed with the fourth light emitting diode chip 101d on the third chip bonding pad 102c, and the first light emitting diode chip 101a is wired to the first electrode 103a. Bonded, the second and third LED chips 102b and 102c are wire-bonded to the second electrode 103b, and the fourth LED chip 102d is wire-bonded to the third electrode 103c.

The light emitting window 107 formed by filling the inside of the cup 104 with a transparent material is formed to have an elongated shape in the direction in which the first to fourth LED chips 101a, 101b, 101c, and 101d are arranged in a line. It has a rectangular shape. A heat dissipation extension pad 106 is formed to extend outwardly from the first, second and third chip bonding pads 102a, 102b and 102c to dissipate heat generated from the light emitting diode chips to the outside. .

On the other hand, as in the present invention, when the light emitting diode chips emitting light of a plurality of wavelengths are configured as one package, it is necessary to effectively dissipate heat emitted from the light source unit.

9, a metal chassis 120 positioned to cover the rear surface of the light guide plate 50 is bent toward the side of the light guide plate 50. The light source unit 60 is mounted to the bent portion 120a. The back surface of the package 70 is mounted on the printed circuit board 65 in a top view so that the light emitting diode package 70 directly faces the light guide plate 50, and the light guide plate 50 and the light emitting diode package 70 are mounted on the printed circuit board 65. The distance d between them is within 5 mm. The light source unit 60 is soldered to the chassis 120, or bonded or screwed through the heat transfer material 115 to be coupled. In this structure, heat generated from the light emitting diode package 70 may be discharged at the shortest distance leading to the light emitting diode chip, the back surface of the package, the back surface of the printed circuit board 60, and the metal chassis 120.

Meanwhile, in order to eliminate an air gap between the light guide plate 50 and the light emitting diode package 70, a transparent resin material 63 such as epoxy or silicon is filled. The transparent resin material 63 may be inserted in the form of a gel, a liquid cured form, or an adhesive film.

Furthermore, a lens or a transparent or translucent diffusion sheet 62 may be further provided on the exposed surface of the light emitting window 94 of the light emitting diode package. When the lens or the diffusion sheet 62 is provided, the distance between the light guide plate 50 and the light emitting diode package 70 may be set within 10 mm.

10A and 10B show another embodiment of the heat dissipation structure of the photometric backlight unit according to the present invention.

The metal chassis 120 is positioned to cover the rear surface of the light guide plate 50, and the metal chassis 120 is bent toward the side surface of the light guide plate 50. The metal block 110 is disposed between the bent portion 120a and the light guide plate 50, and the light source unit 60 is coupled to the metal block 110. The metal block 110 is attached to the metal chassis 120 via the heat transfer material 115. In addition, a heat sink 130 is mounted on a rear surface of the metal chassis 120 positioned at the light source unit 60 and the metal block 110. As shown in FIG. 10B, the heat pipe 125 extends from the inside of the metal block 110 to the inside of the heat sink 130. The heat pipe 125 extends in the longitudinal direction of the metal block 110 to be bent outward and then be bent at the heat sink 130 again. It has the form of a child.

Although not shown in FIG. 10A, as shown in FIG. 9, a lens or a diffusion sheet is provided between the light emitting window of the LED package 60 and the light guide plate 50, and a filler may be inserted to remove the air gap.

Heat generated in the light emitting diode package 60 is transferred to the metal block 110, and is transferred from the metal block 110 to the heat sink 130 through the heat pipe 125 to be dissipated. Heat that is not generated through the heat sink 130 is radiated through the metal chassis 120 and thus has excellent heat radiating effect.

The heat pipe 125 may be buried in the metal block 110 as shown in FIG. 10A, and as illustrated in FIG. 10B, the heat pipe 125 may have an “U” shaped groove having an open upper side in the metal block 110. 112 may be formed and installed in the groove 112. Thus, by forming the "U" -shaped groove 112 to increase the heat dissipation surface area can be more effectively radiated.

Next, FIG. 12 illustrates a case where the light source unit 60 is disposed on the upper side and the lower side of the light guide plate 50. First heat sinks 141a and 141b are provided on upper and lower side surfaces of the light source unit 60 to discharge heat generated from the light source unit 60. However, in the structure in which the light source unit 60 is disposed on the upper side and the lower side of the light guide plate 50 as described above, heat generated in the upper portion is accumulated in the upper portion more than the lower portion due to the influence of convective heat. Therefore, a difference occurs in the thermal distribution in the upper and lower portions, which causes non-uniform light efficiency in the upper and lower portions of the light guide plate, which may result in non-uniformity of the color temperature and luminance distribution of the backlight unit. In order to alleviate this irregular temperature variation, the rear surface of the first heat sink 141b from the lower part of the rear surface of the first heat sink 141a to distribute the heat generated in the upper part and the heat generated in the lower part evenly. The first heat pipe 143a extending to a part is installed. In addition, a second heat pipe 143b may be further provided symmetrically with the first heat pipe 143a. The first heat pipe 143a and the second heat pipe 143b are disposed to surround the light guide plate 50. In addition, second heat sinks 145a and 145b are further provided on upper and lower surfaces of the first and second heat pipes 143a and 143b, respectively.

In addition, the color sensor 150 detects a change in the color temperature and the brightness of the backlight unit and feeds it back to the driving circuit of the light source unit to adjust the applied current to maintain the color temperature and the brightness at the initial set value. The color sensor 150 may be mounted on a surface of the light guide plate 50 where the light source unit is not disposed. The color sensor 150 senses the color temperature and brightness of the backlight unit to maintain a constant color temperature and brightness at all times to improve the image quality of the display device.

The above embodiments are merely exemplary, and various modifications and equivalent other embodiments are possible to those skilled in the art. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the invention described in the claims below.

As described above, the light-emitting backlight unit according to the present invention includes a light emitting diode package including a light emitting diode package including one light emitting diode chip that emits light of at least two wavelength bands in one package, arranged on at least one surface of the light guide plate in a light emitting diode. Colors are mixed in the package for release. Thus, the space for mixing colors is not required separately, thereby greatly reducing the distance between the light source unit and the light guide plate, and reducing the thickness of the backlight unit to enable thinning and miniaturization.

In addition, by arranging and packaging a plurality of LED chips in a line in a package, the direction angle can be increased to greatly reduce the dark portion, and a chip that emits light of a plurality of wavelengths can be appropriately arranged to increase color reproducibility. By employing such a backlight unit in a display device, it can be usefully applied to small and medium sized display devices. In particular, it is possible to commercialize by applying to a professional LCD monitor for special use, such as medical and military of small and medium size that high color reproducibility is required.

Moreover, the CCFL, which is restricted in use by environmental regulations, can be used as a light emitting diode package, and the light emitting diode can be used as an advantageous light source in terms of lifetime or power consumption. In addition, the present invention is to develop a heat dissipation structure capable of efficiently dissipating heat generated from the light emitting diode package to realize a light-emitting backlight unit and a display device employing the light emitting diode package.

Claims (31)

A light guide plate for directing light to a display panel for forming an image; And a light source unit mounted on a printed circuit board so that the multi-chip LED packages packaged with the LED chip emitting light of at least two wavelength regions are disposed on the printed circuit board so as to be perpendicular to the LGP. A photometric type backlight unit. In the lower portion of the liquid crystal panel, a light guide plate having a square shape and an area that is the same as or similar to that of the liquid crystal panel, wherein the light guide plate irradiates light from the side of the light guide plate to the light guide plate. A multi-chip LED package including at least three LED chips emitting at least red light, green light and blue light in one light emitting window is arranged in a line of four or more on the printed circuit board with the rear surface of the light emitting window as a mounting surface. And a light source unit formed as a module, wherein the light source unit is disposed at a distance of 5 mm or less in parallel to the side surface of the light guide plate. The method of claim 1, The light source unit is a light-emitting backlight unit, characterized in that the multi-chip light emitting diode package is composed of a module that is arranged on a rear side of the printed circuit board. The method of claim 1, And a separation distance between the multi-chip LED package and the light guide plate is 5 mm or less. The method of claim 1, The light emitting diode package of claim 1, wherein the light emitting diode chips are arranged in a line so that the light emitted from the light emitting diode package is widely spread. The method of claim 5, And the light emitting diode packages are arranged in a line on at least one surface of the light guide plate in the same direction as the light emitting diode chips. The method of claim 6, The light emitting diode package has a light emitting window of a rectangular shape having a long length in the direction in which the light emitting diode chips are arranged in a line. The method according to any one of claims 1 to 7, The multi-chip LED package includes a first light emitting diode chip emitting red light, a second light emitting diode chip emitting green light, a third light emitting diode chip and a fourth light emitting diode chip emitting blue light. Photometric backlight unit. The method of claim 8, The light-emitting backlight unit of claim 2, wherein the wavelength of the green light emitted from the second LED chip and the third LED chip has a difference in the range of 15-40 nm. The method of claim 9, And the second light emitting diode chip and the third light emitting diode chip are connected in parallel, and the load per chip is 70% or less of the rated power consumption. The method of claim 8, The second light emitting diode chip and the third light emitting diode chip emit light of the same wavelength, the light-emitting backlight unit. The method according to any one of claims 1 to 7, The multi-chip LED package includes a first LED chip emitting red light, a second LED chip emitting green light, and a third LED chip emitting blue light, wherein the second LED chip is a first LED chip. And a larger chip than the third light emitting diode chip. The method of claim 8, The light emitting diode package includes a chip bonding pad to which first to fourth light emitting diode chips are attached, and a heat dissipation extension pad extending from both sides of the chip bonding pad to a side thereof and having a width greater than that of the chip bonding pad. . The method according to any one of claims 1 to 7, And a lens or a diffusion sheet inserted between the multi-chip LED package and the light guide plate. The method according to any one of claims 1 to 7, A photosensitive backlight unit, characterized in that the transparent resin is formed between the multi-chip light emitting diode package and the light guide plate in the form of a gel, cured liquid or adhesive film. The method according to any one of claims 1 to 7, And a metal chassis disposed to surround the rear surface of the light guide plate and the light source unit. The method of claim 16, The metal chassis has a bent portion that is bent toward the light source portion from the rear surface of the light guide plate, and a metal block is further disposed between the light source portion and the bent portion. The method of claim 17, And a heat sink for dissipating heat on the side where the light source is located on the rear surface of the metal chassis. The method of claim 18, And a heat pipe extending outward from the inner portion of the metal block along the length direction of the metal block to the inner portion of the heat sink to direct heat generated from the metal block toward the heat sink. The method of claim 19, And the heat pipe is mounted in a hole penetrated in the lengthwise direction of the metal block or in an “U” -shaped groove opened upward. A light guide plate for directing light to a display panel for forming an image; A light source unit mounted on a printed circuit board so that the multi-chip LED package packaged with the LED chip emitting light of at least two wavelength regions is disposed on the printed circuit board so as to face the light guide plate; And a first heat sink positioned at a rear surface of the upper light source unit and the lower light source unit, respectively. The method of claim 21, A first heat pipe extending from a portion of the upper first heat sink to a right side of the light guide plate and connected to a portion of the lower first heat sink, and extending from a portion of the first heat sink along a left side of the light guide plate A photometric backlight unit comprising a second heat pipe connected to a part of the first heat sink. The method of claim 21, And a separation distance between the multi-chip LED package and the light guide plate is 5 mm or less. The method according to any one of claims 21 to 23, wherein The light emitting diode package of claim 1, wherein the light emitting diode chips are arranged in a line so that the light emitted from the light emitting diode package is widely spread. The method of claim 24, And the light emitting diode packages are arranged in a line in the same direction as the light emitting diode chips in a line. The method of claim 24, The light emitting diode package includes a light emitting window having a rectangular shape having a long length in the direction in which the light emitting diode chips are arranged in a line. A display panel forming an image; And a photometric backlight unit according to any one of claims 1 to 7, for irradiating light to the display panel. The method of claim 27, The multi-chip LED package includes a first light emitting diode chip emitting red light, a second light emitting diode chip emitting green light, a third light emitting diode chip and a fourth light emitting diode chip emitting blue light. Display device. The method of claim 28, And the wavelength of the green light emitted from the second LED chip and the third LED chip has a difference in the range of 15-40 nm. The method of claim 28, And the second light emitting diode chip and the third light emitting diode chip emit green light having the same wavelength. The method of claim 27, The multi-chip LED package includes a first LED chip emitting red light, a second LED chip emitting green light, and a third LED chip emitting blue light, wherein the second LED chip is a first LED chip. And a larger chip than the third light emitting diode chip.

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