JP4678389B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device using an LED chip (light emitting diode chip).

Conventionally, as a light emitting device that obtains white light, for example, an LED chip that emits blue light and a yellow phosphor that emits broad yellow light when excited by blue light emitted from the LED chip are combined to obtain white light. There is something like that (see, for example, Patent Document 1).
JP 2001-148509 A

  However, the conventional example using a single LED chip has a problem in that the light emission efficiency is not good as compared with the size.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light-emitting device in which the light emission efficiency is improved without increasing the size.

  In order to achieve the above object, the present invention provides a plurality of LED chips, a mounting substrate on which the plurality of LED chips are mounted, and all LED chips on the mounting surface side of the LED chip on the mounting substrate made of a transparent material. A sealing part that seals the bonding wire connected to each LED chip, an optical member that is placed over the sealing part, and a molded product that is formed of a transparent material, on the light emitting surface side of the optical member A dome-shaped protective cover that covers the optical member and is disposed in such a manner that an air layer is formed between the light emitting surface and the plurality of LED chips are blue, green, red It includes at least three kinds of LED chips that emit light of the system.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the plurality of LED chips include LED chips that emit yellow or orange light.

  A third aspect of the invention is characterized in that, in the first or second aspect of the invention, the protective cover is formed to have a uniform thickness.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the air layer is formed such that a distance between the light emitting surface and the protective cover is substantially constant. It is characterized by that.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the sealing portion and the optical member are formed of the same material.

  According to the present invention, since a plurality of LED chips are mounted on the mounting substrate, the total area from which light is emitted can be increased as compared with the case where a single LED chip is mounted on the mounting substrate, and the luminous efficiency can be improved. Moreover, the use of a small LED chip does not increase the size.

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

(Embodiment 1)
FIG. 1 is a cross-sectional view of the light emitting device of the present embodiment, FIG. 2 is an exploded perspective view, and FIG. 3 is a plan view of the main part.

  The light emitting device of the present embodiment includes a plurality (eight in this embodiment) of LED chips 10, a mounting substrate 20 on which the plurality of LED chips 10 are mounted, and a mounting surface side of the LED chip 10 on the mounting substrate 20. A frame 40 surrounding all the LED chips 10, and a transparent resin material filled inside the frame 40 to seal each LED chip 10 and the bonding wires 14 connected to the individual LED chips 10; A sealing part 50 having elasticity, an optical member (lens) 60 disposed so as to overlap the sealing part 50, and a molded product obtained by molding a transparent material, the optical member 60 on the light emitting surface 60b side of the optical member 60 And a dome-shaped protective cover 70 disposed in such a manner that an air layer 80 is formed between the light emitting surface 60 b and the frame body 40.

  The mounting substrate 20 includes a heat transfer plate 21 made of a flat, substantially rectangular plate-shaped metal plate, and a substantially rectangular flat plate-like wiring substrate 22 bonded to the surface of the heat transfer plate 21 (the upper surface in FIGS. 1 and 2). It has. The wiring board 22 is, for example, a copper-clad laminate having general heat resistance in which conductor patterns 23 and 23 are formed on one surface side of an insulating base material 22a made of a flame-retardant glass cloth base epoxy resin. (A so-called FR4 substrate), and a substantially rectangular window hole 24 penetrating in the thickness direction is provided at the center. The heat transfer plate 21 is formed in a substantially rectangular flat plate shape that is sufficiently thicker than the wiring substrate 22 by a metal material (Cu, Al, etc.) having a relatively high thermal conductivity. Here, in the window hole 24 of the wiring board 22, a submount member 30 described later is joined to the heat transfer plate 21, and heat generated in each LED chip 10 is transmitted through the submount member 30. Heat is transmitted to the. The heat transfer plate 21 and the wiring substrate 22 are fixed by a fixing material 25 made of an insulating sheet-like adhesive film. Further, each conductor pattern 23 has a portion not covered by the protective cover 70 as an outer lead portion 23b.

  The LED chip 10 is a GaN-based blue LED chip, a GaAs-based red LED chip, or a GaP-based green LED chip that emits three types of light of blue, red, and green, respectively, and each side is approximately 0.2 to 0.5 mm. It is a rectangular parallelepiped. The blue LED chip uses, for example, a conductive substrate (not shown) made of an n-type SiC substrate having a lattice constant or crystal structure close to that of GaN and having conductivity compared to a sapphire substrate as a crystal growth substrate. A light emitting part (not shown) made of a GaN-based compound semiconductor material and having a double hetero structure, for example, is formed on the main surface side of the conductive substrate by an epitaxial growth method (for example, MOVPE method). A cathode electrode (n electrode) which is a cathode side electrode (not shown) is formed on the back surface of the conductive substrate, and is an anode side electrode (not shown) on the surface of the light emitting part (the outermost surface on the main surface side of the conductive substrate). An anode electrode (p electrode) is formed. In short, the LED chip 10 has an anode electrode formed on one surface side and a cathode electrode formed on the other surface side. Since the red LED chip and the green LED chip have the same structure as the blue LED chip, detailed description thereof is omitted. The cathode electrode and the anode electrode are composed of a laminated film of a Ni film and an Au film, but the material of the cathode electrode and the anode electrode is not particularly limited, and a material capable of obtaining good ohmic characteristics For example, Al or the like may be employed. In the present embodiment, the LED chip 10 is mounted on the heat transfer plate 21 so that the light emitting portion is farther from the heat transfer plate 21 than the conductive substrate. However, the light emitting portion of the LED chip 10 is conductive. You may make it mount in the heat-transfer board 21 so that it may become the side near the heat-transfer board 21 rather than a heat conductive board. In consideration of the light extraction efficiency, it is desirable to arrange the light emitting part on the side away from the heat transfer plate 21, but in this embodiment, the conductive substrate and the light emitting part have the same refractive index. Therefore, even if the light emitting part is arranged on the side close to the heat transfer plate 21, the light extraction loss does not become too large.

  The LED chip 10 is formed on the above-described heat transfer plate 21 in a rectangular plate shape larger than the chip size of the LED chip 10, and is caused by a difference in linear expansion coefficient between the LED chip 10 and the heat transfer plate 21. It is mounted via a submount member 30 that relieves stress acting on the LED chip 10. The submount member 30 is made of AlN having a relatively high thermal conductivity and insulating properties, and is formed in a substantially rectangular flat plate shape. The submount member 30 not only functions to relieve the stress but also transfers heat generated by the LED chip 10. The plate 21 has a heat conduction function for transferring heat to a range wider than the chip size of the LED chip 10. On the surface of the submount member 30 on the LED chip 10 side, as shown in FIG. 3, a plurality (total 8) of electrode patterns 31 connected to the cathode electrodes of the individual LED chips 10 are formed. The anode electrode of the LED chip 10 to which the cathode electrode is connected to another electrode pattern 31 is electrically connected via a bonding wire 14 made of a fine metal wire (for example, a gold fine wire, an aluminum fine wire, etc.). In the present embodiment, all of the eight LED chips 10 are connected in series, and the anode electrode of the LED chip 10 on one end side is connected via the conductive pattern 32 for relay and the bonding wire 14 formed on the surface of the submount member 30. The electrode pattern 31 connected to one conductor pattern 23 and connected to the LED chip 10 on the other end side is electrically connected to the other conductor pattern 23 via the bonding wire 14 (FIG. 3). reference). The LED chip 10 and the electrode pattern 31 of the submount member 30 are bonded using lead-free solder such as AuSn or SnAgCu.

  The material of the submount member 30 is not limited to AlN, and may be any material having a linear expansion coefficient that is relatively close to 6H—SiC that is a material of the conductive substrate and a relatively high thermal conductivity. For example, composite SiC, Si Etc. may be adopted.

  Although the silicone resin is used as the transparent resin material of the sealing portion 50 described above, not only the silicone resin but also an acrylic resin may be used.

  On the other hand, the frame 40 has a cylindrical shape and is formed of a transparent resin molded product, and a silicone resin is used as the transparent resin used in the molded product. In short, in the present embodiment, the frame body 40 is formed of a translucent material having a linear expansion coefficient equivalent to that of the transparent resin material of the sealing portion 50. Here, in this embodiment, after the frame body 40 is fixed to the metal substrate 20, the sealing resin 50 is formed by filling (potting) the transparent resin material inside the frame body 40 and thermosetting the same. Yes. In the case where an acrylic resin is used as the transparent resin material instead of the silicone resin, it is desirable that the frame body 40 be formed of a molded product of acrylic resin.

  The optical member 60 is composed of a biconvex lens in which the light incident surface 60a and the light emitting surface 60b on the sealing portion 50 side are formed in a convex curved surface shape. Here, the optical member 60 is formed of a molded product of silicone resin and has the same refractive index as that of the transparent resin material. However, the optical member 60 is not limited to the molded product of silicone resin. You may comprise by goods.

  By the way, the optical member 60 has a light exit surface 60b formed in a convex curved surface shape that does not totally reflect the light incident from the light incident surface 60a at the boundary between the light exit surface 60b and the air layer 80 described above. The light emitted from the side surface of the LED chip 10 propagates through the sealing portion 50, the frame body 40 and the air layer 80 to reach the protective cover 70 and passes through the protective cover 70.

  The protective cover 70 is formed of a transparent material such as silicone resin, and the inner surface 70a is formed in a dome shape along the light emitting surface 60b of the optical member 60 (that is, from the spherical surface corresponding to the light emitting surface 60b of the optical member 60). Is also formed into a part of a spherical surface having a large diameter. Therefore, the distance between the light emitting surface 60b and the inner surface 70a of the protective cover 70 in the normal direction is a substantially constant value regardless of the position of the light emitting surface 60b of the optical member 60. In addition, the protective cover 70 is shape | molded so that the thickness along a normal line direction may become uniform irrespective of a position. The protective cover 70 may be bonded to the peripheral edge of the opening with respect to the wiring substrate 22 by using, for example, an adhesive (for example, silicone resin, epoxy resin). The transparent material used as the material of the protective cover 70 is not limited to the silicone resin, and for example, an acrylic resin, an epoxy resin, glass, or the like may be employed.

  By the way, when using the light-emitting device of this embodiment for the light source of a lighting fixture, it mounts in the instrument main body 100 made from metal (for example, metal with high heat conductivity, such as Al and Cu) via the insulating layer 90 which consists of a green sheet. Is done. The insulating layer 90 has a function of electrically insulating and thermally coupling both the mounting substrate 20 and the instrument main body 100. However, the insulating layer 90 is not limited to an unsintered ceramic body formed into a sheet shape such as a green sheet, and for example, a thermosetting fixing material (for example, an epoxy resin) may be used.

  As described above, in the light emitting device of the present embodiment, since the plurality of LED chips 10 including three types of blue, red, and green are mounted on the mounting substrate 20, white light in which all colors are mixed is obtained, and Compared with the case where one LED chip (usually formed in a rectangular parallelepiped shape having one side of approximately 0.7 to 1 mm) is mounted on the mounting substrate 20, the total area where light is emitted is increased. Luminous efficiency can be improved, and the use of the small LED chip 10 does not increase the size.

(Embodiment 2)
The light-emitting device of this embodiment is demonstrated with reference to FIGS.

  The basic configuration of the light emitting device of the present embodiment is substantially the same as that of the first embodiment, and the optical member 60 that controls the light distribution of the light emitted from the plurality of LED chips 10 includes all the LEDs between the mounting substrate 20 and the LED. The LED chip 10 and a bonding wire electrically connected to the LED chip 10 are formed in a dome shape that is fixed to one surface side (the upper surface side in FIG. 4) of the mounting substrate 20 so as to accommodate the chip 10. The difference is that the sealing portion 50 that seals 14 and 14 is filled in a space surrounded by the optical member 60 and the mounting substrate 20. Here, the protective cover 70 is disposed so that an air layer 80 is formed between the one surface side of the mounting substrate 20 and the light emitting surface 60 b of the optical member 60. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  In addition, the light emitting device according to the present embodiment includes a resin sheet containing a filler made of a filler such as silica or alumina on the other surface side of the mounting substrate 20 as a sheet-like bonding member 91 and having a low viscosity during heating. (For example, an organic green sheet such as an epoxy resin sheet highly filled with fused silica). Thus, when the light emitting device of the present embodiment is used as a light source of a lighting fixture, for example, a fixture main body 100 made of metal (for example, a metal having high thermal conductivity such as Al or Cu) in the lighting fixture (see FIG. 5). ) And the mounting substrate 20 can be joined by the joining member 91. Here, the bonding member 91 made of the resin sheet has electrical insulation properties, high thermal conductivity, high fluidity during heating, and high adhesion to the uneven surface. When joining to the main body 100 via the joining member 91 (the joining member 91 is interposed between the mounting substrate 20 and the instrument main body 100 and then the joining member 91 is heated to thereby heat the mounting substrate 20 and the instrument main body. Can be prevented from occurring between the bonding member 91 and the mounting substrate 20 and the instrument main body 100, and an increase in thermal resistance and variations due to insufficient adhesion can be prevented. Compared to the conventional case where a light emitting device is mounted on a circuit board and a rubber sheet-like heat dissipation sheet such as Sarcon (registered trademark) is sandwiched between the circuit board and the instrument body as in the past. LED Since the heat resistance from the top 10 to the instrument body 100 can be reduced, the heat dissipation is improved, the variation in the thermal resistance is reduced, and the temperature rise of the junction temperature of the LED chip 10 can be suppressed, so the input power is increased. It is possible to increase the optical output.

  Moreover, in this embodiment, the flexible printed wiring board by which the conductor patterns 23 and 23 were formed in the one surface side of the insulating base material 22a consisting of a polyimide film is employ | adopted as the wiring board 22 in the mounting substrate 20, The wiring board 22 is fixed to one surface side (the upper surface side in FIG. 4) of the heat transfer plate 21 via, for example, a polyolefin-based fixing sheet 29 (see FIG. 5). Further, a white resin that covers the conductive patterns 23 and 23 and the portion where the conductive patterns 23 and 23 are not formed in the insulating base material 22a on the surface side opposite to the heat transfer plate 21 side in the insulating base material 22a. A resist layer 26 made of is laminated. Therefore, since the light emitted from the side surface of the LED chip 10 and incident on the surface of the resist layer 26 is reflected by the surface of the resist layer 26, the light emitted from the LED chip 10 is prevented from being absorbed by the wiring substrate 22. Thus, the light output can be improved by improving the light extraction efficiency to the outside. Here, each conductor pattern 23 and 23 is formed in the outer periphery shape a little smaller than half of the outer periphery shape of the insulating base material 22a. In addition, as a material of the insulating base material 22a, FR4, FR5, paper phenol, or the like may be employed.

  Further, in the resist layer 26, the inner lead portions 23 a of the respective conductor patterns 23 and 23 are exposed in the vicinity of the window holes 24 of the wiring substrate 22, and the outer lead portions 23 b of the respective conductor patterns 23 and 23 in the peripheral portion of the wiring substrate 22. In each of the conductor patterns 23 and 23, the inner lead portion 23a exposed in the vicinity of the window hole 24 of the wiring substrate 22 constitutes a terminal portion to which the bonding wire 14 is connected. A circular outer lead portion 23b exposed at the peripheral portion of 22 constitutes an electrode portion for external connection. In addition, the outer lead portion 23b (the right outer lead portion 23b in FIG. 5) to which the anode-side electrode of the LED chip 10 at one end of the two outer lead portions 23b connected in series is electrically connected. Is formed on the outer lead portion 23b (the left outer lead portion 23b in FIG. 5) to which the cathode side electrode of the LED chip 10 at the other end connected in series is electrically connected. Since “−” is displayed, the polarities of both outer lead portions 23a and 23b in the light emitting device can be visually recognized, and erroneous connection can be prevented.

  The optical member 60 is a molded product of a translucent material such as silicone resin, and is formed in a dome shape. Here, in this embodiment, since the silicone resin is adopted as the material of the sealing portion 50 and the optical member 60 is formed of a molded product of the silicone resin, the optical member 60 and the sealing portion 50 are refracted. The difference in rate and the linear expansion coefficient can be reduced. In addition, when the material of the sealing part 50 is an acrylic resin, it is preferable to form the optical member 60 also with an acrylic resin.

  By the way, in the manufacturing method of the light-emitting device described above, for example, after the LED chip 10 and the conductor patterns 23 and 23 connected in series are electrically connected via the bonding wires 14 and 14, respectively, as shown in FIG. As described above, the tip of the nozzle 401 of the dispenser 400 is aligned with the resin injection hole 28 formed continuously from the window hole 24 of the wiring board 22, and the sealing portion 50 is inserted into the gap between the submount member 30 and the wiring board 22. A liquid sealing resin (for example, silicone resin) that becomes a part is injected and cured, and then the liquid sealing that becomes the remaining part of the above-described sealing part 50 inside the dome-shaped optical member 60. After injecting a resin (for example, a silicone resin), the sealing member 50 is formed by placing the optical member 60 at a predetermined position on the mounting substrate 20 and curing the sealing resin. At the same time, a manufacturing method in which the optical member 60 is fixed to the mounting board 20 and then the protective cover 70 is fixed to the mounting board 20 can be considered. Since air bubbles (voids) may be generated, it is necessary to inject a large amount of liquid sealing resin into the optical member 60.

  However, when such a manufacturing method is adopted, when the optical member 60 is arranged at the predetermined position on the mounting substrate 20, a part of the liquid sealing resin is from a space surrounded by the optical member 60 and the mounting substrate 20. Overflowing and spreading on the surface of the resist layer 26, the light extraction of the entire apparatus due to light absorption at the unnecessary portion made of the overflowing sealing resin or irregular reflection of light due to the unevenness of the unnecessary portion, etc. It is conceivable that the efficiency decreases.

  Therefore, in the light emitting device according to the present embodiment, the optical member is disposed between a portion overlapping the ring-shaped end edge of the optical member 60 and a portion overlapping the ring-shaped end edge of the protective cover 70 on the one surface of the mounting substrate 20. A plurality of resin reservoir holes 27 for storing the sealing resin overflowing from the space surrounded by 60 and the mounting substrate 20 are formed apart from each other in the outer peripheral direction of the optical member 60. Here, the resin reservoir hole 27 includes a through hole 27 a formed in the wiring substrate 22 and a recess 27 b formed in a portion corresponding to the through hole 27 a in the heat transfer plate 21, and the thickness of the wiring substrate 22. Even if the thickness of the resin reservoir hole 27 is reduced, the depth dimension of the resin reservoir hole 27 can be increased, and the amount of sealing resin that can be stored in the resin reservoir hole 27 can be increased. The sealing resin cured in step 1 functions as a heat insulating part that prevents heat transfer from the LED chip 10 to the protective cover 70, and the temperature rise of the protective cover 70 accompanying the heat generation of the LED chip 10 can be suppressed.

  In addition, the light emitting device of the present embodiment is disposed between the portion overlapping the ring-shaped end edge of the optical member 60 and the portion overlapping the ring-shaped end edge of the protective cover 70 on the one surface side of the mounting substrate 20. A ring-shaped light absorption preventing substrate 140 that covers each resin reservoir hole 27, and prevents light absorption by the resin portion made of the sealing resin that has accumulated and hardened in each resin reservoir hole 27. This can be prevented by the substrate 140 for use. Here, the light absorption preventing substrate 140 is provided with a white resist layer that reflects light from the LED chip 10 or the protective cover 70 on the surface side opposite to the mounting substrate 20 side. Can be prevented. The light absorption preventing substrate 140 is filled with the sealing resin overflowing when the optical member 60 is arranged at a predetermined position on the mounting substrate 20 in each resin reservoir hole 27, and What is necessary is just to mount on the said one surface side, and when hardening sealing resin after that, it will adhere to the mounting board | substrate 20 with sealing resin. Here, the ring-shaped light absorption preventing substrate 140 is formed with a plurality of notches 142 for exposing minute regions of the resin reservoir holes 27, and the sealing resin in the resin reservoir holes 27 is cured. It is possible to prevent voids from being generated.

  Further, in the light emitting device of this embodiment, the planar size of the sheet-like joining member 91 is set larger than the planar size of the heat transfer plate 21, so that the joining member 91 and the heat transfer plate 21 are on the same plane. Compared with the case where it is formed in size, the creeping distance between the heat transfer plate 21 and the appliance main body 100 that is a metal member can be increased, and lightning surge resistance when used as a light source for a lighting fixture is improved. (However, the creepage distance between the light emitting device and the metal member, which is generally required for indoor lighting fixtures and outdoor lighting fixtures, is different, and outdoor lighting fixtures have a longer creepage distance. Required). Here, the thickness of the sheet-like joining member 91 needs to be designed in accordance with the lightning surge resistance required withstand voltage, but it is desirable to set it thinner from the viewpoint of reducing the thermal resistance. Therefore, regarding the joining member 91, after setting the thickness, the plane size may be set so as to satisfy the requirement of the creepage distance.

  In the light emitting device of the present embodiment described above, the portion of the one surface of the mounting substrate 20 that overlaps the edge of the optical member 60 on the mounting substrate 20 side and the portion of the protective cover 70 that overlaps the edge of the mounting substrate 20 side. Since the resin reservoir hole 27 is formed therebetween, the sealing resin stored in the resin reservoir hole 27 does not overflow when the protective cover 70 is fixed to the mounting substrate 20. Since it is possible to suppress the formation of unnecessary parts made of sealing resin overflowing on the surface, light extraction efficiency due to light absorption at the unnecessary parts and irregular reflection of light due to irregularities of the unnecessary parts Can be suppressed, and the light output can be increased.

  Here, in the light emitting device of this embodiment, since the plurality of resin reservoir holes 27 are provided apart from each other in the outer peripheral direction of the optical member 60, the mounting substrate of the optical member 60 on the one surface of the mounting substrate 20 is provided. An unnecessary portion made of a sealing resin on the one surface of the mounting substrate 20 while shortening the distance between the portion overlapping the edge on the 20 side and the portion overlapping the edge on the mounting substrate 20 side of the protective cover 70. Can be suppressed, and the conductor patterns 23 and 23 can be prevented from being separated by the resin reservoir hole 27, so that the resistance of the power supply path to the LED chip 10 can be reduced. .

  By the way, in each above-mentioned embodiment, although a SiC substrate is adopted as a substrate for crystal growth in LED chip 10, a GaN substrate may be used instead of a SiC substrate, and when a SiC substrate or a GaN substrate is used. Compared to the case where a sapphire substrate which is an insulator is used as the crystal growth substrate, the thermal conductivity of the crystal growth substrate is high and the thermal resistance of the crystal growth substrate can be reduced. Moreover, in each said embodiment, although only one electrode is provided in the one surface side on the opposite side to the base member in the LED chip 10, both electrodes are provided in the said one surface side. It may be provided. Further, in each of the above embodiments, three types of LED chips 10 of blue, red, and green are used. However, the color rendering property may be improved by including the LED chip 10 that emits orange or yellow light. I do not care. The LED chip that emits orange or yellow light may be formed of, for example, a GaAsP-based compound semiconductor material.

It is sectional drawing which shows Embodiment 1 of this invention. It is an exploded perspective view same as the above. It is a top view of the principal part same as the above. It is a schematic sectional drawing which shows Embodiment 2 of this invention. It is a principal part schematic exploded perspective view of the lighting fixture using the same as the above. It is explanatory drawing of a manufacturing method same as the above. It is a schematic exploded perspective view same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 LED chip 20 Mounting board 21 Metal plate 22 Wiring board 23 Conductor pattern 30 Submount member 40 Frame 50 Sealing part 60 Optical member (lens)
70 protective cover

Claims (5)

A plurality of LED chips, a mounting substrate on which the plurality of LED chips are mounted, and all LED chips and bonding wires connected to the LED chips are sealed on the mounting surface side of the LED chip on the mounting substrate made of a transparent material. A sealing part to be stopped, an optical member arranged to overlap the sealing part, and a molded product obtained by molding a transparent material, covering the optical member on the light emission surface side of the optical member and between the light emission surface And a dome-shaped protective cover disposed in a form in which an air layer is formed,
The plurality of LED chips include at least three types of LED chips that emit blue, green, and red light.   The light emitting device according to claim 1, wherein the plurality of LED chips include LED chips that emit yellow or orange light.   The light-emitting device according to claim 1, wherein the protective cover is formed to have a uniform thickness.   The light emitting device according to any one of claims 1 to 3, wherein the air layer is formed so that a distance between the light emitting surface and the protective cover is substantially constant.   The light emitting device according to claim 1, wherein the sealing portion and the optical member are formed of the same material.

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