KR20080025715A - Light emitting diode module for backlight unit and backlight using the same - Google Patents

Abstract

An LED(Light-Emitting Diode) module for backlighting and a backlight unit using the same are provided to simplify a manufacturing process and effectively radiate the heat generated from LED chips by mounting the LED chips directly on an MCPCB(Metal Core Printed Circuit Board), without using LED packages. An LED module(100) for backlighting comprises an MCPCB(101), a plurality of LED chips(103) and a resinous packing part(104). A circuit pattern is formed on the upper surface of the MCPCB(101). The LED chips(103), mounted on the circuit pattern of the MCPCB(101), are arranged in a line. The resinous packing part wraps each of the LED chips. The resinous packing part which contains green and red fluorescent substances emits white light.

Description

LED module for backlight and back light unit using the same {LIGHT EMITTING DIODE MODULE FOR BACKLIGHT UNIT AND BACKLIGHT USING THE SAME}

The present invention relates to a light emitting diode (LED) module for a backlight and a backlight unit using the same. The present invention relates to a backlight LED module capable of obtaining a uniform line light source, and to a high quality using the LED module. It relates to a backlight unit.

In general, an LED that converts an electrical signal into light using characteristics of a compound semiconductor has advantages such as longer life, lower driving voltage, and lower power consumption than other light emitters. In addition, it has the advantages of excellent response speed and impact resistance as well as small size and light weight.

The LED is not only used as a light source of a portable electronic device such as a mobile phone but also recently used as a back light unit (BLU) and a light source of illumination of a liquid crystal display (LCD). Here, the LED light source used for the backlight unit forms a LED module in which a plurality of LEDs are mounted on a substrate. However, since the LED is a point light source, it is disadvantageous to realize a uniform distribution of light in the light guide plate or high luminance as compared to fluorescent light of an elongated light source.

1A and 1B are a cross-sectional view and a plan view of an LED module 20 to which a conventional LED package is applied. 1A and 1B, the LED module 20 includes a metal core printed circuit board (MCPCB) 11 and LED packages 10 mounted on the metal core printed circuit board 11. ), And a lens 15 formed on the LED package 10, the LED package 10 molding the LED package main body 13 on which the LED chip 12 is mounted and the LED chip 12. It has a resin packaging part 14 to make. Such a conventional LED module 20 performs a separate LED package process, because the LED package 10 is attached to the metal core printed circuit board 11 by a reflow method, the process is complicated and the unit cost Has the disadvantage of rising. In addition, since heat generated from the LED chip 12 is discharged through various steps such as the LED package main body 13 and the metal core printed circuit board 11, there is a problem in that heat is not effectively emitted.

FIG. 2 is a plan view illustrating an edge type backlight unit using the LED module 20 of FIG. 1A. Referring to FIG. 2, the edge type backlight unit has a light guide plate 21 and an LED module 20 disposed on side surfaces of the light guide plate 21. The light guide plate 21 serves to receive the light generated by the LED chip 12 and to disperse the light throughout the upper surface. This LED package 10 can not adjust the directivity angle up to more than ± 120 °. Therefore, if the distance from which the light generated from each LED chip can be sufficiently mixed is not secured, the dark portion D may occur in the light incident portion of the light guide plate 21. In order to remove the dark portion D, the number of LEDs may be increased to narrow the gap between the LEDs and the LEDs, thereby increasing the uniformity of the line light source. However, there is a problem in that the manufacturing cost is increased. On the contrary, in the case where the mixing distance of the light is sufficiently secured, the luminance may be lowered and the size of the backlight unit may increase.

In addition, since the LED package 10 is mounted on the metal core printed circuit board 11, the LED module 20 occupies a space corresponding to the volume of the LED package 10, thereby limiting the size of the entire backlight unit.

The present invention is to solve the above problems, it is an object of the present invention to provide an LED module that can obtain an effective heat emission and a uniform line light source.

Still another object of the present invention is to provide a high quality backlight unit in which no dark portion is generated in the light incident portion of the light guide plate using the LED module.

In order to achieve the above technical problem, the LED module for backlight according to the present invention includes a metal core printed circuit board having a circuit pattern formed on the upper surface; A plurality of LED chips mounted on the circuit pattern and arranged in a line; Each of the LED chips is packaged and has a resin packaging part extending to a part of an upper surface of the printed circuit board outside each of the LED chips.

Preferably, the resin packaging portion may include a phosphor. The resin packaging part may be made of any one of a silicone resin, an epoxy resin, a urethane resin, and a mixture thereof. The resin packaging may be convex or hemispherical.

The backlight unit according to the present invention includes a backlight LED module which is a linear light source and a light guide plate for dispersing light generated from the LED module, wherein the LED module is disposed on one side of the light guide plate or on both sides facing each other. In the unit, the LED module includes a metal core printed circuit board having a circuit pattern formed on the upper surface; A plurality of LED chips mounted on the circuit pattern and arranged in a line; Each of the LED chips is packaged to include a resin package extending to a part of an upper surface of the printed circuit board outside each of the LED chips.

Preferably, the resin packaging portion may include a phosphor. The resin packaging part may be made of any one of a silicone resin, an epoxy resin, a urethane resin, and a mixture thereof. The resin packaging may be convex or hemispherical.

According to the present invention, by directly mounting the LED chip on the metal core printed circuit board without a package, it is possible to simplify the manufacturing process of the LED module, reduce the cost of the product and effectively release the heat generated from the LED chip. It is also advantageous to miniaturize the product.

In addition, by molding the resin packaging part up to the LED chip and a portion of the upper surface of the printed circuit board adjacent to the LED chip, it is possible to improve the directivity angle of the LED chip emission light, the uniformity of the linear light source in the linear LED module is increased. When such an LED module is used as a light source of the edge type backlight unit, the dark part of the light guide plate incident part may be removed.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. But. Embodiments of the invention may be modified in many different forms and should not be construed as limited to the embodiments set forth herein. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

3A and 3B are cross-sectional and plan views, respectively, of the LED module 100 according to the embodiment of the present invention. 3A and 3B, the LED module 100 according to the present invention includes a metal core printed circuit board 101, a plurality of LED chips 103, and a resin packaging unit 104.

The upper surface of the metal core printed circuit board 101 has a circuit pattern 102 that can be electrically connected to an external circuit. The metal core printed circuit board 101 is a printed circuit board whose substrate is a metal plate. The metal plate formed on the metal core printed circuit board 101 serves as a heat sink. Therefore, when the LED chip 103 is mounted on the metal core printed circuit board 101 without a package as in the present invention, heat generated from the LED chip 103 is directly transferred to the metal plate to effectively generate heat. do.

Referring to FIG. 3B, the circuit pattern 102 formed on the metal core printed circuit board 101 is illustrated as a first lead 102a and a second lead 102b. However, the present invention is not limited thereto, and the LED chip 103 may be mounted and electrically connected to another circuit pattern. The first lead 102a and the second lead 102b are formed as a thin metal plate on the metal core printed circuit board 101, and are arranged to be spaced apart at regular intervals to form different electrodes.

As the material of the LED chip 103, materials satisfying the conditions such that the light emission wavelength is present in the visible or near infrared region, the light emission efficiency is high, and the p-n junction can be manufactured are suitable. Such materials include gallium nitride (GaN), gallium arsenide (GaAs), gallium phosphide (GaP), gallium-arsenide-phosphorus (GaAs1-x Px), gallium-aluminum-arsenic (Ga1-xAlxAs), indium phosphide (InP) ), Compound semiconductors such as indium-gallium-phosphorus (In1-xGaxP) may be used.

The light emission is largely divided by recombination of free carriers and recombination at an impurity emission center. In this case, the wavelength of the light generated by recombination to the impurity emission center varies depending on the type of the impurity added to the semiconductor. For example, in the case of gallium phosphide, light emission in which zinc and oxygen atoms are involved is yellow red (wavelength 570 nm to 700 nm), and light emission in which nitrogen atoms are involved is blue green (wavelength 430 nm to 500 nm). In other words, the light generated from the LED chip 103 has a unique color (wavelength) depending on the type of impurities and the semiconductor material. Light generated from the LED chip 103 may be combined with a phosphor (not shown) of the resin packaging part 104 to emit white light. This will be described later.

The LED chip 103 may be fixed on the first lead 102a by adhesive means such as silver epoxy or entectic solder. The LED chip 103 and the second lead 102b may be connected by a wire (not shown). Alternatively, the LED chip 103 and the second lead 102b may be connected in a flip-chip manner.

By mounting the LED chip 103 directly on the circuit pattern 102 formed on the metal core printed circuit board 101 as shown in the present invention, the process of the LED module 100 is simplified, and the production cost of the product is reduced. Can be reduced. In addition, the product can be miniaturized.

The resin packing unit 104 wraps each of the LED chips 103 and extends to a part of the upper surface of the metal core printed circuit board 101 on the outside of each of the LED chips 103. By forming the resin packaging part 104 in this way, the light emitted from the LED chip 103 is widely spread on the front surface. Accordingly, the directing angle of the LED module 100 is increased. Therefore, when the directing angle of the LED module 100 is increased, the uniformity of the linear light source of the LED module 100 is improved. The resin packing part 104 may have various shapes in order to increase the orientation angle. For example, the resin packaging 104 may be convex or hemispherical. As the resin packing part 104 is convex upward, the orientation angle becomes narrower.

In addition, since the resin packing part 104 has a convex shape or a hemispherical shape, there is a probability that light emitted from the resin packing part 104 to the outside becomes smaller than the critical angle at the interface between the resin packing part 104 and the outside. The total reflection decreases and the light extraction efficiency increases. Further, due to the convex shape or the hemispherical shape, the light generated from the LED chip 103 is incident as perpendicularly as possible to the interface between the resin packaging part 104 and the outside. Therefore, the path of light is minimized, and the amount of light loss in the substrate is further smaller.

It is preferable that the refractive index of the resin packaging part 104 is smaller than the refractive index of the LED chip 103. By doing so, it is possible to suppress the total reflection that may occur in the refractive index difference to increase the light extraction efficiency.

The material of the resin packaging 104 may be made of one of an epoxy, a silicone resin, a urethane resin, and a mixture thereof. A well-known process, such as a dispensing process, may be used as an input process of the resin packaging part 104.

The resin packaging part 104 may include a phosphor (not shown). The phosphor is a material that absorbs and emits light emitted from the LED chip 103 or absorbs and emits light emitted from another phosphor. White light can be realized by mixing three primary colors of red, green, and blue, or mixing two colors in a complementary color relationship. For example, blue LEDs may combine with yellow phosphors or with red / green phosphors to produce white light. As another example, an ultraviolet LED may combine with red / green / blue phosphors to produce white light. As another example, a red LED, a green LED, and a blue LED may be combined to emit white light.

Blue phosphors include ZnS: Ag, ZnS: Ag + In ₂ O ₃ , ZnS: Zn + In ₂ O ₃ , (Ba, Eu) MgAl ₁₀ O ₁₇ Green phosphors include ZnS: Cu, Y ₂ Al ₅ O ₁₂ : Tb, Y ₂ O ₂ S: Tb, and the red phosphors include Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, YVO. ₄ : Eu etc. In addition, yellow phosphors include YAG: Ge, YAG: Ce, and the like.

The resin packing part 104 may disperse a scattering agent or a diffusing agent that scatters light. By scattering or diffusing the light by the scattering agent or the diffusing agent dispersed in the resin packing part 104 can obtain a wide range of light distribution characteristics can further increase the directivity angle. Accordingly, the LED module 100 can obtain a uniform line light source.

4 is a plan view illustrating a backlight unit using the LED module 100 for backlight of FIG. 3A. Referring to FIG. 4, the backlight unit includes a light guide plate 110 and an LED module 100, and the LED module 100 may be disposed on one side or both sides of the light guide plate 110 facing each other. Light generated from the LED chip 103 of the LED module 100 (particularly, white light) is incident on the side surface (light receiving part) of the light guide plate 110. The light guide plate 110 serves to receive the light generated from the LED module 100 and to disperse the light throughout the upper surface.

Since the LED module 100 according to the present invention increases the directivity as described above, the mixing distance t of the light generated from each LED chip 103 is reduced. As the mixing distance t decreases, the dark portion at the light incident portion of the light guide plate 110 may be removed. By removing the dark part, a high quality backlight unit can be realized.

5 is a photograph for comparing a light incident part of a backlight unit according to the present invention with a conventional backlight unit. 5A is a photograph illustrating a conventional backlight unit. Referring to FIG. 5A, a conventional LED module (not shown) illustrated in FIG. 1A is disposed on an upper side surface of the light guide plate 21. In the conventional LED module, the direction angle is limited, and the dark part D is generated in the light incident part of the light guide plate 21. 5B is a photograph showing a backlight unit according to the present invention. Referring to FIG. 5B, an LED module (not shown) according to the present invention is disposed on an upper side surface of the light guide plate 110. In the LED module according to the present invention, since a directing angle is increased to show a uniform line light source, a dark portion at a light incident portion of the light guide plate 110 does not occur.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims, and various forms of substitution, modification, and within the scope not departing from the technical spirit of the present invention described in the claims. It will be apparent to those skilled in the art that changes are possible.

1A and 1B are a cross-sectional view and a plan view of a conventional LED module for backlight.

2 is a plan view illustrating a conventional edge type backlight unit.

3A and 3B are a cross-sectional view and a plan view, respectively, of an LED module for backlight according to an embodiment of the present invention.

4 is a plan view illustrating a backlight unit according to an embodiment of the present invention.

5A and 5B are photographs showing a conventional backlight unit and a backlight unit of the present invention, respectively.

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

101: metal core printed circuit board 102: circuit pattern

102a: first lead 102b: second lead

103: LED chip 104: resin packaging portion

110: light guide plate

Claims (10)

A metal core printed circuit board having a circuit pattern formed on an upper surface thereof; A plurality of LED chips mounted on the circuit pattern and arranged in a row; And And wrapping each of the LED chips to extend a resin packaging part extending to a part of an upper surface of the printed circuit board outside each of the LED chips. The resin packaging unit includes a green and red phosphors to emit white light, LED module for backlight. The method of claim 1, The resin packaging unit is a backlight LED module, characterized in that it comprises any one of a silicone resin, an epoxy resin, a urethane resin and mixtures thereof. The method of claim 1, The green phosphor is at least one of ZnS: Cu, Y ₂ Al ₅ O ₁₂ : Tb and Y ₂ O ₂ S: Tb LED module for a backlight. The method of claim 1, The red phosphor includes at least one of Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, and YVO ₄ : Eu. A metal core printed circuit board having a circuit pattern formed on an upper surface thereof; A plurality of LED chips mounted on the circuit pattern and arranged in a row; And And wrapping each of the LED chips to extend a resin packaging part extending to a part of an upper surface of the printed circuit board outside each of the LED chips. The resin packaging unit includes a blue, green and red phosphors to emit white light LED module for the. The method of claim 5, The resin packaging unit is a backlight LED module, characterized in that it comprises any one of a silicone resin, an epoxy resin, a urethane resin and mixtures thereof. The method of claim 5, The blue phosphor is ZnS: Ag, ZnS: Ag + In ₂ O ₃ , ZnS: Zn + In ₂ O ₃ and (Ba, Eu) MgAl ₁₀ O ₁₇ LED module for a backlight comprising at least one of. The method of claim 5, The green phosphor is at least one of ZnS: Cu, Y ₂ Al ₅ O ₁₂ : Tb and Y ₂ O ₂ S: Tb LED module for a backlight. The method of claim 5, The red phosphor is at least any one of Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu and YVO ₄ : Eu LED module for a backlight. The LED module for a backlight according to any one of claims 1 to 9; And, And a light guide plate for dispersing light generated from the backlight LED module. The backlight LED module is disposed on one side of the light guide plate and both sides facing each other.

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