KR20100012849A - Warm white light emitting apparatus and back light module comprising the same - Google Patents

Abstract

PURPOSE: A warm white light emitting apparatus and a back light module comprising the same are provided to implement excellent light of warm light around a blackbody radiation curve by combining a first LED fluorescent substance with a second fluorescent substance. CONSTITUTION: A first LED- fluorescent substance combination(110) generates a basic light such as a white or a yellow white color. A second LED- fluorescent substance combination(120) generates CRI adjustment light for making a worm white light of 2500-4500 color temperature with the basic light. A first LED- fluorescent substance combination includes at least one blue LED and more than one the fluorescent substance 500-600nm peak wavelength. A second LED- fluorescent substance combination includes at least one blue LED, UV LED, and more than one fluorescent substance of peak wavelength over 600nm.

Description

Warm white light emitting device and backlight module including the same {WARM WHITE LIGHT EMITTING APPARATUS AND BACK LIGHT MODULE COMPRISING THE SAME}

The present invention relates to a warm white light emitting device, and a warm white light emitting device comprising an LED-phosphor combination for generating a white or yellowish white primary light and an LED-phosphor combination for generating light for adjusting the CRI of the basic light. will be.

The development of white light emitting devices using LED as a light source for white light emission is increasing. LED is basically composed of p-type and n-type semiconductor junction, and it is a device using light emitting semiconductor that emits energy corresponding to band gap of semiconductor in the form of light by combining electron and hole when voltage is applied.

White light emitting devices are known which produce white light using three primary LEDs of red, green and blue colors. Such a white light emitting device has a problem in that the circuit configuration is complicated, the uniform white light is difficult to be realized due to the distance difference between the three primary LEDs, and the economy is also poor. In addition, the method using the three primary color LED has a limit in improving the color rendering and color reproducibility of the white light.

FIG. 16 is a CIE1931 chromaticity coordinate diagram showing the full color of a conventional white light emitting device. Referring to FIG. 16, a triangle representing the three primary color coordinates used by the NTSC standard is displayed, and a red ( R), green (G), blue (B) The light of the white region may be implemented according to the change in the slope of the coordinates by the current applied to the LEDs. At this time, the white region is displayed along a black body locus curve (BBL curve), and the slope of the black body radiation curve increases from ∞ to about 4000K based on the horizontal axis and the vertical axis xy and then decreases after about 4000K. It has an aspect. Therefore, the red, blue, and green LEDs alone do not implement light of a warm color white warm white region following the blackbody radiation curve.

On the other hand, a white light emitting device for producing white light by using a combination of a blue LED and a yellow phosphor is also known. Such a conventional white light emitting device has the advantages of a simple circuit configuration and a low cost, but of course the color rendering is inferior. However, the color reproducibility is also greatly reduced due to the low light intensity at long wavelengths.

Further, a light emitting device that produces white light by a combination of red and green phosphors having different excitation wavelengths and a blue LED chip is also known in the art. Such a white light emitting device has blue, green, and red peak wavelengths, and therefore, color rendering and color reproducibility are better than those of light emitting devices using a kind of yellow phosphor. However, such a light emitting device has a problem in that the light loss is large and the efficiency of the phosphor is also low because heterogeneous phosphors are positioned without being separated from each other in one encapsulant.

The incandescent lamp emits a warm white light of about 2854K color temperature according to the CIE1931 standard. It provides a warm and comfortable atmosphere and enhances the aesthetics of colored objects. In the field of LEDs, studies have been made by the inventors of the present invention to realize warm white light near the blackbody radiation curve similarly to or more than incandescent lamps. As a result of such studies, the present inventors have found problems of light efficiency and / or degradation of phosphors of the prior art that use heterogeneous phosphors without isolating them, and problems of color rendering or color reproducibility caused when using a single phosphor. At the same time, we have developed a technology to realize high quality warm white light.

Accordingly, one technical problem of the present invention is that it is difficult to make a conventional LED-phosphor combination through the adoption of an LED-phosphor combination that emits white or yellow-white primary light and another LED-phosphor combination that adjusts the CRI of the primary light. It is a technical object of the present invention to provide a device for easily realizing high quality warm white light near a blackbody radiation curve.

In addition, another technical problem of the present invention is that, by using two LED-phosphor combinations, it is possible to simply implement a good warm white light near the black body radiation curve, and the combination of the two LED-phosphor combinations to generate a basic light It is to provide a warm white light emitting device using an AC LED suitable for a large display board or a large monitor as an LED.

According to one aspect of the invention, a first LED-phosphor combination for generating a white or yellowish white primary light, and a second LED for generating CRI tunable light for producing warm white light of 2500 to 4500 K color temperature together with the primary light. A warm white light emitting device comprising a phosphor combination is provided.

According to a conventional classification standard, white light is divided into warm white, pure white, and cool white light according to color temperature. However, in the present specification, 'warm white light' is defined as white light except cool white light, that is, white light including warm white light and pure white light in a conventional meaning. In the present specification, the term 'basic light' means light that becomes a material of warm white light near the color rendering good black body radiation curve to be finally obtained.

Preferably, the primary light generated by the first LED-phosphor combination is a square defined by color coordinates (0.29, 0.45), (0.33, 0.37), (0.52, 0.47), (0.45, 0.54) on the CIE chromaticity diagram. The CRI tunable light generated by the second LED-phosphor combination is defined as color coordinates (0.36, 0.34), (0.44, 0.2), (0.67, 0.32), (0.55, 0.44) on the CIE chromaticity diagram. Losing is in the area of the square.

Preferably, the second LED-phosphor combination may be provided in plural numbers around the first LED-phosphor combination.

Advantageously, said first LED-phosphor combination comprises at least one blue LED and at least one phosphor within a 500-600 nm peak wavelength range, said second LED-phosphor combination comprising at least one blue LED At least one phosphor having a peak wavelength greater than 600 nm. Alternatively, the second LED-phosphor combination can include at least one UV LED and at least one phosphor having a peak wavelength greater than 600 nm.

Preferably, the first LED-phosphor combination and the second LED-phosphor combination are arranged independently of each other in a single package, for which each of the first and second LED-phosphor combinations is divided by a partition wall. The cavity may be located in each of the corresponding cavities of the single package. Alternatively, the corresponding phosphors of each of the first and second LED-phosphor combinations may be provided to individually cover the corresponding LEDs of each of the first and second LED-phosphor combinations to enable the independent placement. .

According to one embodiment, the first LED-phosphor combination and the second LED-phosphor combination may be included in different packages, respectively. In this case, the warm white light emitting device includes a frame including a base portion on which the different packages are mounted and a reflecting portion reflecting light from the first LED-phosphor combination and the second LED-phosphor combination of the different packages. It includes more.

According to one embodiment, the LED of the first LED-phosphor combination and the LED of the second LED-phosphor combination may be operated separately. In this case, light of a color other than the warm white light of the target blackbody radiation curve subgroup can be additionally used. The LEDs of the first LED-phosphor combination and the LEDs of the second LED-phosphor combination may be mounted together on a single lead terminal or may be individually mounted on a plurality of different lead terminals. In addition, at least one of the LEDs may be mounted on another chip mounting unit, for example, a heat sink for heat dissipation, which is not a lead terminal. At this time, the chip mounting portion means all parts on which the LED chip is mounted, the "chip mounting portion" is not limited by the characteristics such as electrical conductivity or thermal conductivity.

According to an embodiment, the first LED-phosphor combination may include at least one of a blue LED, blue, green, and amber phosphor, and the second LED-phosphor combination may include a blue LED or a UV LED, and a night light. Ride-based or sulfite-based red phosphors may be included.

According to another aspect of the invention, there is at least one AC LED and at least one phosphor, a first combination that produces white or yellowish white primary light, at least one DC LED and at least one phosphor, There is provided a warm white light emitting device including a second combination of generating the CRI control light for generating warm white light together with the basic light.

The AC LED may be formed by electrically connecting a plurality of light emitting cells grown in a semiconductor on a single substrate in series or in parallel, or by connecting a plurality of LED chips mounted on a single submount in series and in parallel. In this case, the plurality of light emitting cells of the AC LED or the plurality of LED chips on the submount may be driven under AC power by two series arrays connected in parallel with each other or a series connected LED array connected to a bridge rectifier. Two or more series arrays are alternately activated in the forward and reverse directions so that the light emitting cells or LED chips of the series arrays are alternately operated.

The warm white light emitting device according to an embodiment of the present invention may include a delayed phosphor to reduce flickering, wherein the delayed phosphor is included in at least one of the first combination and the second combination, or It may be included in the encapsulant covering both the first combination and the second combination.

According to an embodiment of the present invention, the first combination and the second combination may be included in different packages, respectively. In this case, the warm white light emitting device may include: a base unit on which the different packages are mounted; The apparatus may further include a frame including a reflector configured to reflect light from the first and second combinations of different packages, and the delay unit may be formed in the reflector.

According to an embodiment of the present invention, the warm white light emitting device has an anti-flickering circuit part connected to the AC LED and the THD phenomenon due to the AC LED, in order to reduce the flickering caused by the AC LED. In order to reduce the number, the AC LED may include at least one of the anti-THD circuitry connected to the circuit.

According to another aspect of the invention, there is provided a backlight module comprising a light guide plate and a warm white light emitting device for supplying light to the side of the light guide plate. The warm white light emitting device may include an outer wall defining a space in which the first LED-phosphor combination and the second LED-phosphor combination are accommodated, and the first LED-phosphor combination and the second LED-phosphor combination. Including a partition wall, the outer wall is in contact with the side of the light guide plate, the partition wall has a lower height than the outer wall is spaced apart from the side of the light guide plate.

According to the present invention, the first LED-phosphor combination for generating white or yellowish white primary light for the color rendering good warm white light near the black body radiation curve, which is difficult to realize with the conventional LED-phosphor combination, and the basic light for black body radiation This can be achieved simply by employing a second LED-phosphor combination that produces CRI tunable light pulling near the curve.

According to another aspect of the present invention, by using two LED-phosphor combinations, it is possible to simply implement a good warm white light near the blackbody radiation curve, and to the LED in the combination of the two LED-phosphor combinations to generate a basic light By using the AC LED, a warm white light emitting device suitable for a large display board or a large monitor can be realized. In addition, a combination of LEDs for generating CRI control light uses a DC LED, which may contribute to reducing the flickering of the warm white light emitting device. Furthermore, by additionally providing a delayed phosphor, or anti-flickering and / or anti-THD circuitry, it is possible to further reduce flickering and / or THD, which are problems of AC LEDs.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to ensure that the spirit of the present invention can be fully conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

The first to third embodiments of the present invention described next with reference to FIGS. 1 to 3 are directed to a light emitting device that implements warm white light by two LED-phosphor combinations each including a blue LED.

<Blue LED Use of: first to third Example >

1 is a cross-sectional view showing a warm white light emitting device according to a first embodiment of the present invention.

As shown in FIG. 1, the warm white light emitting device according to the present embodiment includes first and second LED-phosphor combinations 110 and 120 and cavities for accommodating the LEDs and phosphors of the combinations. It includes a housing 130. In this embodiment, the housing 130 has two cavities 131a and 131b that are independent of each other. In addition, transmissive encapsulants 140a and 140b may be formed in the cavities 131a and 131b to protect LEDs.

In this embodiment, the first LED-phosphor combination 110 includes a first blue LED 112 and a corresponding phosphor 114. The second LED-phosphor combination 120 also includes a second blue LED 122 and a corresponding phosphor 124. The emission peak wavelength range of the first blue LED 112 and the emission peak wavelength range of the second blue LED 122 are preferably about 400 to 470 nm. For example, the yellow phosphor 114 provided in the first LED-phosphor combination 110 has a peak wavelength range of approximately 500 to 600 nm.

 In the present embodiment, the first LED-phosphor combination 110 uses one kind of yellow phosphor 114, but is not limited thereto, and two or more kinds of phosphors in the emission wavelength range of 500 nm to 600 nm may be used. It can be used as a phosphor of one LED-phosphor combination 110. For example, as the phosphor 114 of the first LED-phosphor combination 110, a phosphor in the 500 to 550 nm peak wavelength range and a phosphor in the 550 nm to 600 m peak wavelength range may be used together.

The first LED-phosphor combination 110 generates a basic light of white or yellowish white by mixing blue light by the LED and yellow light by the phosphor. Within the first LED-phosphor combination 110, some of the blue light generated from the blue LED 112 excites the phosphor 114. By such excitation, the phosphor 114 can wavelength convert blue light into yellow light. In addition, the rest of the blue light generated from the blue LED 112 proceeds as it is, avoiding the yellow phosphor 114. By mixing yellow light by wavelength conversion and blue light without wavelength conversion, basic light of white or yellow white color is generated.

However, the basic light as described above is greatly reduced the color rendering, it is required to adjust the CRI. Thus, the primary light is mixed with the CRI tunable light generated by the second LED-phosphor combination, as described below, to produce warm white light near the blackbody radiation curve.

The second LED-phosphor combination 120 generates CRI-regulated light that is mixed with the primary light produced from the first LED-phosphor combination 110. Warm white light near the blackbody radiation curve, which is difficult to realize with only one LED-phosphor combination, is created by mixing the primary light by the first LED-phosphor combination 110 and the CRI control light by the second LED-phosphor combination. I can make it. As the phosphor of the second LED-phosphor combination 120, a red phosphor whose emission peak wavelength range is larger than 600 nm may be used.

In the CIE 1931 chromaticity diagram illustrated in FIG. 15, the color coordinate range of the basic light is preferably as far as possible from the blackbody radiation curve, that is, the Y coordinate value of the CIE 1931 chromaticity diagram is largely determined. However, it is preferable that the color coordinate range of the basic light is set to such an extent that the color coordinate range can be pulled near the black body radiation curve by the CRI control light having the fixed color coordinate range.

The primary light generated by the first LED-phosphor combination 110 has a rectangular shape defined by color coordinates (0.29, 0.45), (0.33, 0.37), (0.52, 0.47), and (0.45, 0.54) on the CIE chromaticity diagram. The CRI tunable light, which is defined to be within the first region, and is generated by the second LED-phosphor combination 120, is characterized by the color coordinates (0.36, 0.34), (0.44, 0.2), (0.67, 0.32), ( 0.55, 0.44) to be within the second area of the rectangle. At this time, the light obtained by the first LED-phosphor combination 110 and the second LED-phosphor combination 120 is warm white light, not cool white light, and is near the black body radiation curve. The color temperature range of the obtained warm white light may be approximately 2500K to 4500K, most preferably 2500K to 3500K.

As the phosphor 114 capable of realizing the color coordinate region of the basic light together with the blue LED, at least one of an orthosilicate-based yellow phosphor, an amber phosphor, and a green phosphor is preferably yellow. phosphor and a green phosphor (Ba, Sr, Ca, Cu ) 2 SiO4: Eu, and preferably in, amber phosphors _{(Ba, Sr, Ca) 2} SiO 4: preferably Eu. In addition, various kinds of phosphors, such as YAG: Ce, Tag-Ce, Sr ₃ SiO ₅ : Eu, may be used for the first LED-phosphor combination.

In addition, as the phosphor 114 that can implement the color coordinate region of the CRI control light together with a blue LED or a UV LED, for example, (Ca, Sr, Ba) ₂ Si ₅ N ₈ : Eu, (Mg, Ca, Sr) Nightlight-based red phosphors such as AlSiN ₃ : Eu, (Ca, Sr, Ba) Si ₇ N ₁₀ : Eu, (Ca, Sr, Ba) SiN ₂ : Eu, and the like may be used, and CaAlSiN ₃ : Eu may be used. It is very preferably adapted to the use of red phosphors.

The second LED-phosphor combination 120 is completely separated from the first LED-phosphor combination 110 by a partition 132 between the cavity and the cavity. Thus, the first and second LED-phosphor combinations 110 and 120 may be configured to exchange the action of the phosphor and the LED between the other combinations 110 and 120 until they produce light from each other. You can stop it. The inner wall surfaces of the two cavities 131a and 131b are inclined reflective surfaces. However, the partition wall 132 may be formed as a vertical surface as shown, or the inclination may be reduced compared to other surfaces. Alternatively, the partition wall 132 may be omitted, and each of the phosphors of the first LED-phosphor combination 110 and the second LED-phosphor combination 120 is separated into a cluster form independent from each other in a single encapsulant. Can be located within the scope of the present invention. At this time, it is preferable that the light of the LEDs in one combination does not affect the phosphors of the other combinations at all, but it should not be interpreted that even a slight influence in the acceptable range is limited.

In the present embodiment, each of the first and second blue LEDs 112 and 122 is positioned on the bottom surface of each of the first and second cavities 131a and 131b separated from each other. Belonging to the phosphor combinations 110 and 120, respectively. In addition, the phosphor 114 of the first combination 110 and the phosphor 124 of the second combination 120 may be formed independently of each other in the first and second cavities 131a and 131b. It is located in each of the upper surfaces of the sealing material (140a, 140b). Although not shown, the housing 130 is provided with lead terminals for inputting power to the LEDs.

The phosphors may be included in the form of particles in the coating layer or the secondary molded material formed on the upper surface of the encapsulant, or in the form of particles in the film attached to the upper surface of the encapsulant. Although not shown, the yellow phosphor 114 and the red phosphor 124 may be widely scattered in the form of particles in the first and second encapsulation materials 140a and 140b.

As briefly mentioned above, the second LED-phosphor combination 120 is mixed with the primary light produced from the first LED-phosphor combination 110 to achieve a pink light close to red, ie, to adjust the CRI of the primary light. Generate CRI tunable light. Within the second LED-phosphor combination 120, blue light generated from the second blue LED 122 excites the red phosphor 124. By such excitation, the red phosphor 124 can produce wavelength converted pink light. This pink light is preferably used for color temperature adjustment of white light.

Ideally, all light generated from the second blue LED 122 may work with the red phosphor 124, but in practice, some of the blue light from the second blue LED 122 is emitted to the outside as it is. However, even though such blue light comes from the second LED-phosphor combination 120, the blue light is mixed with the yellow light wavelength-converted by the yellow phosphor 114 in the first LED-phosphor combination 110 to be described above. It can contribute to making one white light, which means that it is not necessary to limit blue light emission from the second LED-phosphor combination 120.

2 illustrates a warm white light emitting device according to a second embodiment of the present invention. Referring to FIG. 2, the warm white light emitting device of the present embodiment, like the previous embodiment, has a first LED-phosphor combination 110 having a first blue LED 112 and a yellow phosphor 114, and a second blue light. And a second LED-phosphor combination 120 having an LED 122 and a red phosphor 124.

Differences from the first embodiment described above are that both the first and second LED-phosphor combinations 110, 120, and, moreover, the encapsulant 140, are all located within a single cavity 131 of the housing 130. And the formation position and formation method of the yellow phosphor 114 and the red phosphor 124 are different. In the present embodiment, the yellow phosphor 114 and the red phosphor 124 separately cover the first blue LED 112 and the second blue LED 122. The method of covering the LED with the phosphor may include a method of doping the LED with a liquid resin containing the phosphor, a method using a reflector containing the phosphor, a method of coating the phosphor on the LED by electrophoresis, or some other method. have.

Also in this embodiment, the first blue LED 112 and the yellow phosphor 114 covering the same constitute the first LED-phosphor combination 110 for producing white or yellowish white primary light, and the second blue LED ( 122 and the red phosphor 124 covering it constitute a second LED-phosphor combination 120 that produces pink light for CRI regulation.

3 shows a warm white light emitting device according to a third embodiment of the present invention. The warm white light emitting device of this embodiment, like the previous embodiment, has a first LED-phosphor combination 110 having a first blue LED 112 and a yellow phosphor 114, a second blue LED 122, and a red color. A second LED-phosphor combination 120 with phosphor 124, wherein both the first and second LED-phosphor combinations 110, 120 are located within a single cavity 131 of the housing 130.

 Unlike the previous embodiments, only the second blue LED 122 of the second LED-phosphor combination 120 is individually covered by the red phosphor 124, and the blue LED of the first LED-phosphor combination 110 112 is surrounded by only the encapsulant 140. The yellow phosphor 114 of the first LED-phosphor combination 110 is provided on the top surface of the encapsulant 140 or inside the encapsulant 140. In the present embodiment, the encapsulant 140 encapsulates not only the first blue LED 112 but also the red phosphor 124 and the second blue LED 122 covered by the encapsulant 140.

According to the present embodiment, in the case of the first LED-phosphor combination 110, the blue light generated from the first blue LED 112 may be a yellow phosphor (a part of which is located on the top surface of the encapsulant 140 (or inside the encapsulant)). 114) is wavelength-converted to yellow light, and the other part is mixed with the yellow light without wavelength conversion to produce a white or yellowish white basic light. In the case of the second LED-phosphor combination 120, the color temperature of the white light is controlled by a red phosphor 124, which directly and individually covers a significant amount of blue light from the second blue LED 122. Converted to pink light used for. At this time, since the yellow phosphor has a much higher energy level than the red phosphor, the light emitted by the red phosphor does not have a substantial effect on the yellow phosphor. Thus, the above application of covering only the second blue LED 122 individually with the red phosphor 124 is possible.

A fourth embodiment described next with reference to FIG. 4 relates to a warm white light emitting device that partially uses a UV LED.

<Blue LED Wow UV LED Use of: fourth Example >

4 illustrates a warm white light emitting device according to a fourth embodiment of the present invention. Referring to FIG. 4, the warm white light emitting device of the present embodiment includes a first LED-phosphor combination 110 including a blue LED 112 and a yellow phosphor 114, a UV LED 122 ′, and a red phosphor ( 124 ') and a second LED-phosphor combination 120'. Both the first and second LED-phosphor combinations 110, 120 ′ are located within a single cavity 131 of the housing 130. Each of the blue LED 112 and the UV LED 122 'is individually covered by a yellow phosphor 114 and a red phosphor 124'. Encapsulant 140 encapsulates all elements of the first and second LED-phosphor combinations 110, 120 ′. In this case, it is preferable that the second LED-phosphor combination 120 'has a peak wavelength of greater than 600 nm for the phosphor 124', and the UV LED 122 'has a peak wavelength within a range of 250 to 400 nm.

Although not specifically shown, if the use of UV LEDs in the second LED-phosphor combination that generates CRI tunable light is satisfied, the structure separating the first LED-phosphor combination and the second LED-phosphor combination may vary. 1, 12, 13, and 14.

The fifth to eighth embodiments described next with reference to FIGS. 5 to 11 relate to a warm white light emitting device using an AC LED as a blue LED of a first LED-phosphor combination that generates basic light.

< AC LED Use of: fifth to eighth Example >

5 is a cross-sectional view showing a warm white light emitting device according to another embodiment of the present invention. Referring to FIG. 5, in the warm white light emitting device of the present embodiment, one first LED-phosphor combination 110 and a plurality of second LED-phosphor combinations 120 are installed in a housing 130 of a single package. In this case, the plurality of second LED-phosphor combinations 120 is disposed around the first LED-phosphor combination 110. According to the present embodiment, the white or yellowish white primary light generated by the first LED-phosphor combination 120 is biased to one side with the CRI-mixed light generated from the plurality of second LED-phosphor combinations 120 positioned around it. It can be mixed evenly without. Thus, the combinations can produce more uniform warm white light without color deviation.

In this case, it is preferable that the first blue LED 112 of the first LED-phosphor combination 110 is an AC LED operated by an alternating current, and an enlarged view of FIG. 5 illustrates a chip structure of the AC LED. It is. Referring to this, the AC LED chip is formed by the growth of semiconductor layers on the substrate 112-1 and in series by the wirings W ₁ , W ₂ ,..., W _{n -1} , W _n . It includes a plurality of connected light emitting cells (C ₁ , C ₂ , ..., C _{n -1} , C _n ).

Each of the plurality of light emitting cells C ₁ , C ₂ ,..., C _{n -1} , C _n is an n-type semiconductor sequentially formed on a substrate 112-1 or a buffer layer thereon (not shown). A layer 1121, an active layer 1122, and a p-type semiconductor layer 1123. In this case, the transparent electrode layer 112-2 may be formed on the p-type semiconductor layer 1123. In addition, part of the active layer 1122 and the p-type semiconductor layer 1123 are removed from a portion of the n-type semiconductor layer 1121, and a light emitting cell adjacent to, for example, a portion of the n-type semiconductor layer 1121 is removed. An electrode that can be connected with a p-type semiconductor layer by wiring can be provided.

One wiring W _{1 is} formed between an n-type semiconductor layer 1121 of one light emitting cell W ₁ and an electrode of a p-type semiconductor layer 1123 of another light emitting cell W ₂ adjacent to the light emitting cell. Connect. In addition, the series array of the plurality of light emitting cells may be inversely connected to the series array of other light emitting cells on the same substrate.

As described above, the AC LED 112 grows an n-type semiconductor layer, an active layer, a p-type semiconductor layer, and the like on the substrate, and the semiconductor layers are divided into a plurality of light emitting cells C ₁ , C ₂ ,. After separation into C _{n -1} , C _n ), the light emitting cells can be connected in series and in parallel. On the other hand, the AC LED may be made by mounting a plurality of LED chips made in advance on a submount, and then connecting the plurality of LED chips mounted on the submount in series and in parallel. In such a case, AlN, Si, Cu, Cu-W, Al ₂ O ₃ , SiC, Ceramic, etc. may be used as the material of the submount. If necessary, a material for insulating the submount and each LED chip can be interposed therebetween.

On the other hand, since the AC LED connected to the AC power source is repeatedly turned on and off according to the direction of the current, flickering occurs in which the light emitted from the AC LED flickers. In this case, the above flickering phenomenon may be reduced by using the DC LED operated by the direct current as the LED 122 of the second combination. In addition, in order to further improve the above flickering or THD (Total Harmonic Distortion) phenomenon, the AC LED or its operating circuit, the anti-flickering circuit part and / or anti-THD (Total Harmonic Distortion) in the form of an element or IC It is preferable to connect the circuit part in a circuit. In addition, according to the temperature change of the above-described AC LED and / or DC LED, the current control unit for controlling the current flowing to the AC LED can be connected to the operation circuit of the AC LED.

6 is a cross-sectional view of a warm white light emitting device according to a sixth embodiment of the present invention, and further includes a warm white light emitting device further including an additional circuit unit 150 for reducing a flickering phenomenon, etc. in the package. Shows. The circuitry 150 may be an anti-flickering circuitry that improves flickering or an anti-THD circuitry that improves THD, which is an AC LED 112 of the first LED-phosphor combination 110. Is electrically connected to the lead terminal (not shown). The anti-flickering circuit part and / or the anti-THD circuit part may be embedded in a package, such as the circuit part 150 shown in FIG. 6, or may be electrically connected to the AC LED 112 outside the package. The DC LED 122 of the second LED-phosphor combination 120 may be connected with an electrical circuit independent from the power source of the AC LED 112, and additional circuitry may be connected for improving the performance of the electrical circuit DC LED. .

7 shows a warm white light emitting device according to a seventh embodiment of the present invention. Referring to FIG. 7, the warm white light emitting device according to the present exemplary embodiment includes a layer 190 (hereinafter, referred to as a delayed phosphor layer) including a delayed phosphor. The delayed phosphor layer 190 is to reduce the flickering phenomenon of the AC LED 112 and to encapsulate both the first LED-phosphor combination 110 and the second LED-phosphor combination 120. For example, it is coated on the encapsulant 140 of silicon or epoxy material.

The delayed phosphor may be a silicate, aluminate, sulfide phosphor, or the like disclosed in US Pat. Nos. 5,770,111, US Pat. No. 5,839,718, US Pat. (Zn, Cd) S: Cu, SrAl2O4: Eu, Dy, (Ca, Sr) S: Bi, ZnSiO4: Eu, (Sr, Zn, Eu, Pb, Dy) O. (Al, Bi) 2O3, m ( Sr, Ba) O.n (Mg, M) O.2 (Si, Ge) O 2: Eu, Ln (where 1.5 ≦ m ≦ 3.5, 0.5 ≦ n ≦ 1.5, and M is a group consisting of Be, Zn and Cd) At least one element selected from, Ln is Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, KLu, B, Al, Ga, In, Tl, Sb , Bi, As, P, Sn, Pb, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Cr and at least one element selected from the group consisting of Mn). The delayed phosphor is excited by a portion of the light from the first LED-phosphor combination and the second LED-phosphor combination to emit light in the visible region, for example red, green and / or blue light.

The afterglow time of the delayed phosphor may be 1 msec or more, more preferably 8 msec or more. The upper limit of afterglow time of the delayed phosphor may vary depending on the use of the light emitting device, and is not particularly limited but is preferably 10 hours or less.

Unlike the previous embodiment, the delay phosphor can be applied independently to the first LED-phosphor combination 110 and / or the second LED-phosphor combination 120, which is shown in FIG. 8 according to the eighth embodiment of the present invention. It is well shown in (a) and (b) of FIG. 8.

Referring to FIG. 8A, the delayed phosphor layers 191a and 191b may be, for example, by electrophoresis, using the DC of the AC LED 112 and the second combination 120 of the first combination 110. It may be formed directly on the surface of each of the LEDs 122. Also, referring to FIG. 8B, the delayed phosphor layers 192a and 192b include a surface of a resin part including the general phosphor 114 of the first combination 110 and a general phosphor of the second combination. It may be formed directly on the surface of the resin portion. Alternatively, a delayed phosphor may be included in the resin portion of the first and second combinations. In addition, the delayed phosphor may be applied only to the first combination.

9 and 10 are circuit diagrams showing examples of AC LEDs usable for the first LED-phosphor combination described above. 11 is a graph showing the effect of the delayed phosphor described above.

First, referring to FIG. 9, light emitting cells C ₁ , C ₂ , and C ₃ of an AC LED are connected in series to form a first series light emitting cell array, and other light emitting cells C ₄ , C ₅ , and C ₆ ) is connected in series to form a second series light emitting cell array. Here, the "serial light emitting cell array" means an array of light emitting cells in which a plurality of light emitting cells are connected in series. Both ends of the first and second series light emitting cell arrays are connected to the AC power source 35 and the ground through lead terminals, respectively. The first and second series arrays are connected in anti-parallel between the AC power source 35 and ground. Therefore, when the AC power source 35 is in the positive phase, the light emitting cells C ₁ , C ₂ , and C ₃ included in the first series light emitting cell array are turned on, and the AC power source 35 is in the negative phase. In this case, the light emitting cells C ₃ , C ₄ , and C ₅ included in the second series light emitting cell array are turned on.

Next, referring to FIG. 10, the light emitting cells C ₁ , C ₂ , C ₃ , C ₄ , C ₅ , and C ₆ form a series light emitting cell array, between the AC power source 35 and the series light emitting cell array, and A bridge rectifier including diode cells D1, D2, D3 and D4 is disposed between ground and the series light emitting cell array. An anode terminal of the series light emitting cell array is connected to a node between the diode cells D1 and D2, and a cathode terminal is connected to a node between diode cells D3 and D4. On the other hand, the terminal of the AC power source 35 is connected to the node between the diode cells D1 and D4, and the ground is connected to the node between the diode cells D2 and D3. When the AC power supply 35 has a positive phase, the diode cells D1 and D3 of the bridge rectifier are turned on and the diode cells D2 and D4 are turned off. Thus, current flows to the ground via the diode cell D1 of the bridge rectifier, the series light emitting cell array and the diode cell D3 of the bridge rectifier. On the other hand, when the AC power supply 35 has a negative phase, the diode cells D1 and D3 of the bridge rectifier are turned off and the diode cells D2 and D4 are turned on. Thus, the current flows through the diode cell D2 of the bridge rectifier, the series light emitting cell array and the diode cell D4 of the bridge rectifier to the AC power source.

11 is a dotted line (a) shows the light emission characteristics of the light emitting device including the AC LED when not using the delayed phosphor, solid line (b) of FIG. 10 shows the light emission characteristics of the light emitting device including the AC LED when using the delayed phosphor Indicates. Here, the DC LED included in the light emitting device is not intentionally operated.

Referring to this, when the delayed phosphor is not used, the light emitting device repeats the on-off periodically by applying an AC voltage. If the period of the AC power source is T, two arrays of series-connected light emitting cells operate alternately once during T. Therefore, the light emitting device emits light at a period T / 2, as indicated by the dotted line a. On the other hand, when the AC voltage does not exceed the threshold voltage of the light emitting cells connected in series, the light emitting cells do not operate. Accordingly, the light emitting cells are turned off for a predetermined time between the times at which the light emitting cells operate, that is, for a time when the AC voltage is smaller than the threshold voltage of the light emitting cells. Accordingly, the AC LED may exhibit flickering in the light emitting device due to the interval between the times at which the light emitting cells operate.

On the other hand, when the delayed phosphor is used, as shown by the solid line b, light is emitted even while the light emitting cells are turned off. Therefore, although the light intensity fluctuates, the time for which light is not emitted is shortened, and when the afterglow time of the delayed phosphor is long, the light emitting device emits light continuously. When a typical household AC power supply is applied at a voltage of about 60 Hz, one cycle of the power supply is about 16.7 msec, and the half cycle is about 8 msec. Therefore, the time that all the light emitting cells are turned off during the operation of the light emitting device is less than 8 msec, so that the flickering phenomenon can be sufficiently alleviated when the delayed phosphor is 1 msec or more. In particular, when the afterglow time of the delayed phosphor is similar to the time when all of the light emitting cells are turned off, the light emitting device can emit light continuously.

The delayed phosphor may additionally be provided in addition to the phosphors of the first and second LED-phosphor combinations described above, but alternatively, the phosphors of the first and second LED-phosphor combinations may be replaced with delayed phosphors.

 In the above embodiments, a warm white light emitting device having a structure including both a first LED-phosphor combination and a second LED-phosphor combination in a single package has been described. In contrast, the warm white light emitting device according to the ninth embodiment of the present invention illustrated in FIG. 12 uses a structure in which the first LED-phosphor combination and the second LED-phosphor combination are respectively included in different packages.

<Use of Multiple Packages: Example 9>

Referring to FIG. 12, the light emitting device of the present embodiment includes a frame 200 including a base 210 and a reflector 220. A first package 231 is installed at the center of the upper surface of the base 210, and a plurality of second packages 232 and 232 are installed around the first package 231. The first package 231 includes a first LED-phosphor combination 110 that generates white or yellowish white primary light, and each of the plurality of second packages 232 and 232 generates a CRI control light. 2 LED-phosphor combinations 120 are included.

As in the previous embodiments, the first LED-phosphor combination 110 may comprise a blue emitting AC LED 112 and one or more phosphors having a 500-600 nm peak wavelength, wherein the second LED-phosphor combination Silver blue LEDs or UV LEDs and one or more phosphors having peak wavelengths greater than 600 nm.

On the other hand, the base unit 210 may be provided with an anti-flickering circuit unit 152 and / or an anti-THD circuit unit 154, and various components such as heat dissipation system, ballast, driver and / or driving circuit The provided circuit 156 may be provided to the base portion 210. In addition, the reflector 220 reflects part of the light emitted from the first and second LED-phosphor combinations 110, but reduces the flickering phenomenon of the AC LED on the inner side of the delayed phosphor layer 193. Is formed.

Hereinafter, a backlight module including a warm white light emitting device according to the present invention will be described with reference to FIGS. 13 and 14.

<Backlight module>

13 and 14 show such backlight modules.

Referring to FIG. 13, the backlight module includes a light guide plate 30 and a light emitting device 10 for supplying light to the light guide plate 30. The light emitting device 10 includes an outer wall 132 that is in contact with a side surface of the light guide plate 30 and accommodates the first and second LED phosphor combinations 110 and 120 therein. In addition, a cavity 134 is formed in the cavity defined by the outer wall 132 to separately receive the first LED-phosphor combination 110 and the second LED-phosphor combination 120. The height of the partition wall 134 is lower than the height of the outer wall 132, and thus, the white or yellowish white primary light generated by the first LED-phosphor combination 110 and the second LED-phosphor combination 120 are generated. For example, a region where pink CRI control light can be mixed is provided adjacent to the side of the light guide plate 30.

 On the left side of the partition wall 134, a first blue LED 112 is located, and the first flat flat surface covering the first blue LED 112 and including one or more phosphors 114 having a peak wavelength of 500 nm to 600 nm. The fluorescent resin layer L1 is formed at a height equal to or smaller than the partition wall 134. In addition, on the right side of the barrier rib 134, a second blue LED 122 is located, and the flat agent including the at least one phosphor 114 covering the second blue LED 122 and larger than a 600 nm peak wavelength. 2 The fluorescent resin layer L2 is formed at a height equal to or smaller than the partition wall 134. In addition, the transparent resin layer T is formed to cover the first fluorescent resin layer L1 and the second fluorescent resin layer L2. The transparent resin layer T has the same height as the outer wall 132 and is in contact with the side surface of the light guide plate 30.

The backlight module illustrated in FIG. 14 also includes a light emitting device 10 including a partition 134 smaller than the outer wall 132. By the partition wall 134, the first LED-phosphor 110 combination and the second LED-phosphor combination 120 are disposed independently of each other. However, different from the backlight module of the previous embodiment is that the resin containing the combination of the phosphor is hemispherical shape and the transparent resin layer (T) of the previous embodiment is omitted. In this case, the hemispherical fluorescent resin parts of the first and second LED-phosphor combinations including the phosphors 112 and 114, respectively, have a height lower than that of the outer wall 132.

1 to 8 are cross-sectional views illustrating a warm white light emitting device according to embodiments of the present invention in which a plurality of LED-phosphor combinations are located in a single package.

9 and 10 are circuit diagrams showing examples of AC LEDs in a combination of generating the basic light of the LED-phosphor combinations of FIGS. 1 to 8.

11 is a graph for explaining light emission characteristics of an AC LED when using a delayed phosphor.

12 is a cross-sectional view showing a warm white light emitting device according to an embodiment of the present invention in which the LED-phosphor combination is located in each of a plurality of packages.

13 and 14 are cross-sectional views illustrating examples of a backlight module employing a warm white light emitting device according to the present invention.

15 is a CIE1931 chromaticity diagram showing color coordinate regions of a basic light and a CRI control light for obtaining warm white light according to the present invention;

16 is a CIE1931 chromaticity diagram showing the full color of a normal white light emitting device.

Claims (11)

A first LED-phosphor combination that produces a basic light of white or yellowish white; And A second LED-phosphor combination comprising the CRI tunable light to produce warm white light of 2500 to 4500 K color temperature together with the primary light, The primary light generated by the first LED-phosphor combination is in a rectangular region defined by color coordinates (0.29, 0.45), (0.33, 0.37), (0.52, 0.47), (0.45, 0.54) on the CIE chromaticity diagram. The CRI control light generated by the second LED-phosphor combination is a rectangular region defined by color coordinates (0.36, 0.34), (0.44, 0.2), (0.67, 0.32), and (0.55, 0.44) on the CIE chromaticity diagram. Warm white light emitting device characterized in that. The method according to claim 1, The first LED-phosphor combination includes at least one blue LED and at least one phosphor within a 500-600 nm peak wavelength range, And said second LED-phosphor combination comprises at least one blue or UV LED and at least one phosphor having a peak wavelength greater than 600 nm. The warm white light emitting device of claim 1, wherein the LED of the first LED-phosphor combination and the LED of the second LED-phosphor combination are individually operable. The warm white light emitting device of claim 1, wherein the first LED-phosphor combination comprises at least one of a blue LED and a blue, green, and amber phosphor. The warm white light emitting device of claim 1, wherein the second LED-phosphor combination includes a blue or UV LED and a nitride-based or sulfide-based red phosphor. The warm white light emitting device of claim 1, wherein the LED of the first LED-phosphor combination is an AC LED and the LED of the second LED-phosphor combination is a DC LED. The warm white light emitting device of claim 6, wherein the AC LED is formed by connecting a plurality of light emitting cells semiconductor-grown on a single substrate in parallel. The warm white light emitting device of claim 6, wherein the AC LED is formed by connecting a plurality of LED chips mounted on a single submount in parallel and in parallel. The warm white light emitting device of claim 6, further comprising a delayed phosphor to reduce flickering caused by the AC LED. The warm white light emitting device of claim 6, further comprising an anti-flickering circuit part connected to the AC LED to reduce the flickering caused by the AC LED. The warm white light emitting device according to claim 6, further comprising an anti-THD circuit part connected to the AC LED to reduce the THD phenomenon caused by the AC LED.

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