KR20100079688A - Led package - Google Patents

Abstract

PURPOSE: An LED package is provided to reduce an optical loss inside an encapsulant due to total reflection by forming an AR coating layer on the surface of the encapsulant. CONSTITUTION: An encapsulant is made of a light transmissive resin. A light emitting unit includes at least one LED chip encapsulated by the encapsulant. An AR(Anti-Reflecting) coating layer(50) is formed on the surface of the encapsulant and reduces the total reflection of light on the surface thereof. A housing(30) comprises a cavity with the encapsulant. The light emitting units are separated from each other and include a plurality of LED chips which emits the light of different colors.

Description

LED package {LED PACKAGE}

The present invention relates to an LED package, and more particularly, to an LED package with reduced total reflection at the encapsulant surface.

LED (Light Emitting Diode) is basically composed of p-type and n-type semiconductor junction, and is a device using a light emitting semiconductor that emits energy corresponding to the band gap of the semiconductor in the form of light by combining electrons and holes when voltage is applied. Such LEDs have many advantages, such as high power characteristics at low current requirements, fast responsiveness, long life, and rigid package construction.

Such LEDs are manufactured and sold in a package structure, which is called an LED package. A typical LED package includes an LED chip (or LED die), lead terminals for inputting current into the LED chip, and an encapsulant that protects the LED chip from the outside while allowing emission of light generated from the LED chip. .

The lead terminals may be lead frames that are cut metal sheets, in which case the lead frames may be supported by a housing (or reflector) having a cavity for receiving the LED chip or by an encapsulant. In the case of an LED package including a housing, an encapsulant is formed in the cavity of the housing to enclose the LED chip. In the case of an LED package including a substrate, the encapsulant encapsulates the LED chip mounted on the substrate, and in this case, the encapsulant may be formed by molding using a mold, in particular, transfer molding.

Conventional LED packages have a high total internal reflection at the interface between them due to the difference in refractive index between the encapsulant and the outside air. This total reflection is a phenomenon in which light does not penetrate the encapsulant surface and is reflected back toward the encapsulant, which causes a large amount of light loss inside the encapsulant. In particular, such light loss is more severe in applications where the encapsulant surface from which light is emitted is flat.

On the other hand, there is also a need in certain applications for the application of making independent lights of different colors in a single LED package and mixing them outside of the LED package. In such a case, it is necessary to prevent unwanted mixing of light inside the encapsulant. However, light propagating independently up to the encapsulant surface is totally reflected at the encapsulant surface and returned to the encapsulant, so that unwanted mixing of light occurs.

One technical problem of the present invention is to provide an LED package in which light loss due to total reflection on the surface of an encapsulant is reduced.

Another technical problem of the present invention is to provide an LED package which makes two or more different independent lights and mixes them outside the package, but minimizes unwanted mixing of the lights due to total reflection at the encapsulant surface. .

According to an aspect of the invention, the light emitting means including an encapsulant formed of a light-transmissive resin, at least one LED chip encapsulated by the encapsulant, and formed on the surface of the encapsulant, to reduce the total reflection of light on the surface An LED package is provided comprising an AR coating layer.

In this case, the LED package may further include a housing having a cavity in which the encapsulant is formed. Moreover, it is preferable that the surface of the said sealing material is flat.

According to one embodiment, the light emitting means comprises a plurality of LED chips spaced apart from each other to emit light of different colors.

According to another embodiment, the light emitting means includes a first LED chip-phosphor combination and a second LED chip-phosphor combination that are arranged independently of one another and emit light of different colors. The first LED chip-phosphor combination includes a first LED chip having a peak wavelength in a range of 400 to 470 nm, and at least one phosphor having a peak wavelength in a range of 500 to 600 nm. The phosphor combination may be composed of a first LED chip having a peak wavelength in the range of 400 to 470 nm and at least one phosphor having a peak wavelength greater than 600 nm. In this case, as the first LED chip, instead of the LED chip of the blue light emitting range having a peak wavelength in the range of 400 to 470nm, LED of the ultraviolet light emitting range having a peak wavelength in the range of 250 to 400nm can be used.

Preferably, the first phosphor is formed to at least partially cover the first LED chip, and the second phosphor is formed to at least partially cover the second LED chip. The apparatus may further include a housing having a cavity in which the encapsulant is formed, and the first LED chip-phosphor combination and the second LED chip-phosphor combination may be separated from each other by a partition wall dividing the cavity. The first LED chip may be an AC LED chip, and the second LED chip may be a DC LED chip.

Preferably, the light generated by the first LED chip-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 light generated by the second LED chip-phosphor combination is defined by color coordinates (0.36, 0.34), (0.44, 0.2), (0.67, 0.32), (0.55, 0.44) on the CIE chromaticity diagram. It is within the area of the rectangle.

According to the embodiments of the present invention, in the LED package including the resin encapsulant, by forming the AR coating layer on the encapsulant surface, it is possible to greatly reduce the light loss in the encapsulant due to total reflection. In addition, in applications where two or more different independent lights are made to be mixed outside the package, total reflection at the surface of the encapsulant minimizes the unwanted mixing of the light, thereby reducing the intended color outside the encapsulant, Light of color temperature and / or color rendering index (CRI) can be easily obtained. Warm white light with good color rendering through the adoption of the first LED chip-phosphor combination that generates white or yellowish white primary light and the second LED chip-phosphor combination that generates CRI control light that pulls the basic light near the black body radiation curve In this case, by using the above-described AR coating layer on the surface of the encapsulant, the phosphor of the first LED chip-phosphor combination and the phosphor of the second LED chip-phosphor combination can work more independently. The color rendering of the warm white light will be easier to implement. In this case, the use of the AC LED chip as the LED chip in the combination which generates the basic light among the two LED-phosphor combinations can reduce the flickering caused by the AC LED chip.

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 to those skilled in the art will fully convey. 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.

1 is a cross-sectional view showing an LED package according to a first embodiment of the present invention.

Referring to FIG. 1, the LED package according to the present embodiment includes a housing 30 having an upper opening cavity 31, an LED chip 12 mounted on a bottom surface of the cavity 31, and the LED. A light-transmitting encapsulant 40 formed in the cavity 31 to protect the chip 12. The encapsulant 40 may be formed of various light transmitting resins, and preferably, epoxy or silicone resin is used. In addition, the LED package includes a phosphor 14 covering the LED chip 12 in the encapsulant 40.

The housing 30 is preferably a reflector having a property that the inner wall surface of the cavity 31 reflects light. Although not shown, lead frames for applying power to the LED chip 12 are supported by the housing 30, and the lead frames extend from the cavity inside the housing to the outside of the housing 30. In addition, wire bonding or flip chip bonding using a bonding wire may be used for electrical connection between the lead frame and the LED chip 12.

The LED chip 12 and the phosphor 14 constitute the light emitting means of the LED package. The LED chip 12 emits itself upon application of current, while the phosphor 14 emits light from the LED chip 12. It is excited by the emitted light and emits light of a wavelength different from that of the LED chip 12. It is also within the scope of the present invention to include only the LED chip without the phosphor as the light emitting means.

In this embodiment, the encapsulant 40 has a flat surface that causes a lot of total reflection. However, the anti-reflecting (AR) coating layer 50 is formed on the flat surface, and the AR coating layer 50 can greatly reduce the reflectance of the surface on which it is located. The solid arrows in FIG. 1 show an example of a path through which light travels when using the AR coating layer 50 as in the embodiment of the present invention. In addition, FIG. 1 shows the light reflected by the interface between the encapsulant 40 and air when the AR coating layer 50 is absent and returned to the inside with a dotted arrow. In this case, the AR coating layer 50 is formed by coating various media layers having different refractive indices on the surface of the encapsulant 40, that is, the interface between the air and the encapsulant, in the wavelength range of light.

 The AR coating layer 50 is particularly advantageous when applied to an LED package having a flat surface encapsulant 40 with relatively high total reflection, but the surface shape of the encapsulant 40 is hemispherical, or is a convex or concave curved surface. Or other shapes.

2 is a cross-sectional view showing an LED package according to a second embodiment of the present invention.

Referring to FIG. 2, first, second and third LED chips 12a, 12b and 12c are mounted on the bottom surface of the cavity 31 of the housing 30 as light emitting means. The first, second and third LED chips 12a, 12b, and 12c emit light having different wavelengths. In the present embodiment, the first LED chip 12a is a blue LED chip and the second LED chip. 12b is a green LED chip, and the third LED chip 12c is a red LED chip. However, the use of green, blue, and red LED chips is just one example, and the type of LED chips, the number of LED chips, and the partial use of phosphors as light emitting means may be variously changed. .

The LED package according to the present embodiment, like the previous embodiment, is provided with an AR coating layer 50 on the encapsulant 40 surface. The AR coating layer 50, like the previous embodiment, can minimize the light loss due to total reflection. In addition, the AR coating layer 50 may be suitably adapted to a particular use or application in which light mixing in the encapsulant 40 should be excluded.

3 is a cross-sectional view showing an LED package according to a third embodiment of the present invention.

As shown in FIG. 3, the LED package according to the present embodiment includes a first and second LED chip-phosphor combinations 110 and 120 as light emitting means, and a cavity for accommodating the LED chips and phosphors of the combinations. And a housing 130 with 131.

In the present embodiment, the first LED-phosphor combination 110 includes a first blue LED chip 112 and the corresponding phosphor 114. In addition, the second LED chip-phosphor combination 120 includes a second blue LED chip 122 and a corresponding phosphor 124. It is preferable that the emission peak wavelength range of the first blue LED chip 112 and the emission peak wavelength range of the second blue LED chip 122 are approximately 400 to 470 nm. For example, the yellow phosphor 114 provided in the first LED chip-phosphor combination 110 has a peak wavelength range of approximately 500 to 600 nm.

 In the present embodiment, the first LED chip-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 the first LED chip-phosphor combination 110. For example, as the phosphor 114 of the first LED chip-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 chip-phosphor combination 110 generates a basic light of white or yellowish white by mixing blue light by the LED chip and yellow light by the phosphor. In the first LED chip-phosphor combination 110, a part of the blue light generated from the first blue LED chip 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 first blue LED chip 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 chip-phosphor combination 120 generates CRI-controlled light that is mixed with the primary light produced from the first LED chip-phosphor combination 110. Warm white light near the black body radiation curve, which is difficult to realize with only one LED-phosphor combination, is used to mix the primary light by the first LED chip-phosphor combination 110 and the CRI control light by the second LED chip-phosphor combination. Can be made by As the phosphor of the second LED chip-phosphor combination 120, a red phosphor whose emission peak wavelength range is larger than 600 nm may be used. In this case, as the LED chip of the second LED chip-phosphor combination 110, a UV LED chip having a peak wavelength within a range of 250 to 400 nm may be used instead of the blue LED chip.

On the CIE 1931 chromaticity diagram shown in FIG. 4, it is preferable that the color coordinate range of the basic light is as far as possible from the blackbody radiation curve, that is, the Y coordinate value of the CIE 1931 chromaticity diagram is large. 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 chip-phosphor combination 110 is a square 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 generated by the second LED chip-phosphor combination 120 is determined to be within the first region of the color coordinates (0.36, 0.34), (0.44, 0.2), (0.67, 0.32) on the CIE chromaticity diagram. , Within the second area of the rectangle defined by (0.55, 0.44). At this time, the light obtained by the first LED chip-phosphor combination 110 and the second LED chip-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 chip, at least one of an orthosilicate-based yellow phosphor, an amber phosphor, and a green phosphor is preferable. a yellow phosphor and a green phosphor (Ba, Sr, Ca, Cu ) 2 SiO4: Eu it is desirable in, amber phosphors _{(Ba, Sr, Ca) 2} SiO 4: preferably Eu. In addition, various kinds of phosphors, such as YAG: Ce, Tag-Ce, and Sr ₃ SiO ₅ : Eu, may be used.

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

The LED package according to the present exemplary embodiment suppresses mixing of the basic light by the first LED chip-phosphor combination 110 and the basic light by the second LED chip-phosphor combination 120 inside the encapsulant 140. It comprises an AR coating layer 150 for. Using the AR coating layer 150, the primary light and the CRI control light is suppressed from being reflected into the encapsulant 140 at the interface between the encapsulant 140 and the outside air, which is the combination of the LED chip in a combination It inhibits light from exciting the phosphors in different combinations, thereby contributing to obtaining the intended warm white light.

5 is a cross-sectional view showing an LED package according to a fourth embodiment of the present invention.

Referring to FIG. 5, the housing 130 includes a partition 132 inside the cavity, and the partition 132 divides the cavity into two small cavities 131a and 131b. The first LED chip-phosphor combination 110 is located in one of the divided cavities 131a, and the second LED chip-phosphor combination 120 is located in the remaining cavities 131b. Since the configuration of the remaining LED package is the same as the previous embodiment and described above, the description thereof will be omitted.

6 is a cross-sectional view showing an LED package according to a fifth embodiment of the present invention. Referring to FIG. 6, the LED package according to the present embodiment includes one first LED chip-phosphor combination 110 and a plurality of second LED chip-phosphor combinations 120 in the housing 130. In this case, the plurality of second LED chip-phosphor combinations 120 is disposed around the first LED chip-phosphor combinations 110.

In this case, it is preferable that the first blue LED chip 112 of the first LED-phosphor combination 110 is an AC LED chip operated by an alternating current, and an enlarged view of FIG. 5 illustrates the structure of the AC LED chip. Is shown. 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 chip 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 ... C _n-1 , C _n ), and the light emitting cells may be connected in series and in parallel. Alternatively, the AC LED chip 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 chip 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 a DC LED chip operated by a direct current as the LED chip 122 of the second combination.

In the LED package according to the present embodiment, the AR coating layer 150 may be formed on the surface of the encapsulant 140 as in the previous embodiment. The AR coating layer 150, like the previous embodiments, prevents light loss due to total reflection and prevents unwanted mixing of different types of light in the encapsulant. In this context, "unwanted mixing" means that the light from the LED chips in one combination is mixed to act on the phosphors in the other combination. On the other hand, the coating layer 150 of the present embodiment is formed to cover the upper surface of the housing through the sealing material to facilitate the coating process.

Although the AR coating layer 150 is used in the above-described application of producing warm white light with the first LED chip-phosphor combination and the second LED chip-phosphor combination, the AR coating layer 150 is not necessarily advantageous for such an application. Note, however, that it is advantageous only in certain applications where the mixing between the lights within the encapsulant needs to be minimized or controlled.

1 is a cross-sectional view showing an LED package according to a first embodiment of the present invention.

2 is a cross-sectional view showing an LED package according to a second embodiment of the present invention.

3 is a cross-sectional view showing an LED package according to a third embodiment of the present invention.

FIG. 4 is a CIE1931 chromaticity diagram showing color coordinate regions of primary light and CRI control light for obtaining warm white light by the LED package shown in FIG. 3; FIG.

5 is a cross-sectional view showing an LED package according to a fourth embodiment of the present invention.

6 is a cross-sectional view showing an LED package according to a fifth embodiment of the present invention.

Claims (11)

An encapsulant formed of a light transmitting resin; Light emitting means including at least one LED chip encapsulated by the encapsulant; And Is formed on the surface of the encapsulant, LED package comprising an AR coating layer to reduce the total reflection of light on the surface. The LED package according to claim 1, further comprising a housing having a cavity in which the encapsulant is formed. The LED package according to claim 1 or 2, wherein the surface of the encapsulant is flat. The LED package according to claim 1, wherein the light emitting means comprises a plurality of LED chips spaced apart from each other and emitting light of different colors. The LED package according to claim 1, wherein the light emitting means includes a first LED chip-phosphor combination and a second LED chip-phosphor combination that are disposed independently of each other and emit light of different colors. The method according to claim 5, wherein the first LED chip-phosphor combination is composed of a first LED chip having a peak wavelength in the range of 400 to 470nm, and at least one phosphor having a peak wavelength in the range of 500 to 600nm, the second The LED chip-phosphor combination includes an LED chip having a peak wavelength in the range of 400 to 470 nm and at least one phosphor having a peak wavelength greater than 600 nm. The method of claim 5, wherein the first LED chip-phosphor combination comprises a first LED chip having a peak wavelength in the range of 400 to 470 nm, and at least one first phosphor having a peak wavelength in the range of 500 to 600 nm. 2 LED chip-phosphor combination comprises a first LED chip having a peak wavelength in the range of 250 to 400 nm and at least one second phosphor having a peak wavelength greater than 600 nm. The LED package according to claim 6 or 7, wherein the first phosphor is formed to at least partially cover the first LED chip, and the second phosphor is formed to at least partially cover the second LED chip. . The method of claim 6 or 7, further comprising a housing having a cavity in which the encapsulant is formed, wherein the first LED chip-phosphor combination and the second LED chip-phosphor combination are separated from each other by partition walls dividing the cavity. LED package, characterized in that located. The LED package according to claim 6 or 7, wherein the first LED chip is an AC LED chip, and the second LED chip is a DC LED chip. The light generated by the first LED chip-phosphor combination is defined as color coordinates (0.29, 0.45), (0.33, 0.37), (0.52, 0.47), (0.45, 0.54) on the CIE chromaticity diagram. The light generated by the second LED chip-phosphor combination in the rectangular region is determined by the color coordinates (0.36, 0.34), (0.44, 0.2), (0.67, 0.32) and (0.55, 0.44) on the CIE chromaticity diagram. LED package, characterized in that in the area of the losing square.

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