HK1148338A - Lighting apparatus with leds - Google Patents

Description

Lighting apparatus with LED

The present application is a divisional application of an invention patent application having an application date of 21/12/2006, an application number of 200680048537.9, and an invention name of "lighting apparatus with LED".

Technical Field

The present invention relates to a lighting device having an LED (light emitting diode).

Background

Heretofore, research into a light emitting device by using an LED chip and a phosphor (fluorescent pigment, fluorescent dye, etc.) as a wavelength conversion material excited by light from the LED chip to emit light of a color different from the light emission color of the LED chip has been widely conducted and developed. The light emitting device can emit light having a color different from that of the LED chip by combining the LED chip with a phosphor, thereby commercializing a white light emitting device (generally referred to as a white LED). The white light emitting device emits white light (light emission spectrum of white light) by combining a phosphor with an LED chip that emits light such as blue light, ultraviolet light, or the like.

Recently, as the output of LED chips increases, research and development of white LEDs as lighting devices have been actively conducted. Japanese patent laid-open No. 2003-59332 proposes an LED unit (LED module) including a circuit board on which a plurality of white LEDs are mounted.

Japanese patent laid-open nos. 2003-168829 and 2001-203396 propose structures configured to be able to efficiently discharge heat generated by the respective light emitting portions of the LED chip while accompanying high light output. However, in the conventional LED unit, the respective LED chips are directly electrically connected to the conductive patterns on the circuit board, and thus heat generated from the LED chips is spread on the circuit board via the electrical connection portions. Therefore, it is necessary to attach a heat dissipation plate made of metal to the bottom surface of the circuit board to enhance the heat conduction performance over the entire range of the circuit board, thereby increasing the cost of the circuit board. Further, when such an LED unit is included, the lighting device needs to interpose an insulating plate (dielectric sheet) between the metal-made body and the metal plate of the circuit board in order to protect the LED unit from a lightning-resistant surge current (surge), and to enhance a heat conduction performance by thermally connecting the metal plate of the circuit board to the metal-made body including a part of the lighting device. However, in this case, since there are two insulating layers interposed on a heat conduction path from the LED chip to the metal-made body through the circuit board, that is, the insulating layers of the circuit board and the insulating plate, a heat conduction performance cannot be sufficiently formed.

Disclosure of Invention

In view of the above problems, the present invention aims to provide a light emitting device having a Light Emitting Diode (LED), which is capable of suppressing a temperature rise in an LED chip to achieve high light output and reduce the cost of a circuit board. The light emitting device according to the present invention includes: a main body 90 made of metal; a plurality of LED chip units 1, each of which includes an LED chip and a pair of lead terminals 42, 43 electrically connected to electrodes of the LED chip; and an insulating layer 80 disposed between the main body 90 and the LED chip unit 1 to form electrical insulation and thermal connection between the main body and the LED chip unit. The circuit board 20 is formed with a plurality of windows 23 through which the respective LED chip units 1 extend, respectively, and the lead terminals are held in electrical contact with the circuit pattern 22, and the respective LED chip units are thermally connected to the main body 90 at the bottom surfaces thereof through the insulating layer 80. With this configuration, the insulating layer 80 can transfer heat from the LED chip to the main body without passing through the circuit board, so that it is possible to reduce thermal resistance between the light emitting portion of the LED chip and the main body for enhancing heat conduction performance and suppressing an increase in junction temperature (junction temperature) of the LED chip. Therefore, input power can be increased as compared with the related art, and high light output can be achieved. In addition, it is also possible to use a relatively inexpensive circuit board, such as a glass epoxy board, as the circuit board instead of a metal board, regardless of its heat dissipation capability, thereby reducing the cost of the circuit board.

According to an aspect of the present invention, there is provided a light emitting device having an LED, including: a body made of metal; a plurality of LED chip units, each of which includes an LED chip and a pair of lead terminals electrically connected to electrodes of the LED chip; a circuit board formed with a circuit pattern, the circuit board configured to supply power to the respective LED chip units; an insulating layer disposed between the main body and the plurality of LED chip units to form electrical insulation and thermal connection between the main body and the LED chip units; and a chip mounting member for supporting the LED chip, wherein the circuit board is formed with a plurality of windows through which the respective LED chip units extend, and the lead terminals are held in electrical contact with the circuit pattern at the periphery of the windows, the respective LED chip units are thermally connected to the main body at bottom surfaces thereof through the insulating layer, first ones of the lead terminals are integrally formed on one side edge of the chip mounting member, second ones of the lead terminals are disposed apart from the other side edge of the chip mounting member, and the insulating layer is interposed between the main body and the chip mounting member and the respective lead terminals.

Preferably, each LED chip unit has a bottom surface defined by lead terminals 42, 43 mounted on an insulating layer 80, so that heat generated in the LED is efficiently conducted from the lead terminals to the main body through the insulating layer.

Preferably, the lighting device is formed with: light-transmitting members 91, 200 for passing visible light from the respective LED chip units; and a mirror 24 formed on a top surface of the circuit board 20 opposite to the light transmitting member to reflect the visible light. With this configuration, the mirror can reflect the visible light totally reflected by the light transmitting member after being emitted from each LED chip unit 1, and thus can enhance the light output.

Preferably, the circuit pattern 22 and the mirror 24 are formed on the top surface of the circuit board 20.

The circuit pattern 22 may be formed on the bottom surface of the circuit board 20. In this case, the circuit pattern and the mirror may be made of appropriate materials and formed of appropriate patterns, increasing the degree of pattern design and increasing the surface area of the mirror to further enhance the light output.

Preferably, the mirror is made of aluminum to enhance the reflectivity of light having a wavelength in the visible region.

Preferably, the body is shaped as a disc having on one face: a notch 192 for accommodating therein each LED chip unit 1 and the circuit board; and a wire insertion hole 194 formed at the bottom of the recess, extending through the center of the body, for passing a power supply cable connected to the center of the circuit board. This configuration does not require space for pulling the cable in the recess 192 of the body, and thus can make the body thin.

In a preferred embodiment of the present invention, the body is provided with attachment screw holes 195 disposed at the periphery of the recess 192 of the body to allow a plurality of attachment screws to pass through the surface of the body to secure the body 90 to the support material. Preferably, a window 211 is provided in a metal frame-shaped decorative cover 210 attached to the main body to cover the periphery of the recess 192 and the respective attachment screws on the surface of the main body to expose the light output surface of the light transmitting member. With this configuration, the main body can be easily attached to a supporting material such as a ceiling by the attachment screws hidden behind the trim cover.

Preferably, the light-transmitting member is formed at a portion thereof opposite to the corresponding LED chip unit with a plurality of lenses for controlling orientation of light from the LED chip unit, and the rest of the light-transmitting member is made of metal. This configuration allows controlling the orientation of the light from each LED chip unit. Since the portion of the light-transmitting member other than the lens is made of metal, the heat conduction performance can be enhanced as compared with other light-transmitting members entirely made of synthetic resin, glass, or the like, so that the rise of the junction temperature of the LED chip can be further suppressed.

Further, each LED chip unit preferably includes: a heat conductive plate 121; made of a thermally conductive material, and mounting an LED chip onto the heat conductive plate; a sub-mount member 30 interposed between the LED chip and the heat conductive plate for relieving stress acting on the LED chip due to a difference in linear thermal expansion coefficient between the LED chip and the heat conductive plate; and an insulating plate 122 mounted on the heat conductive plate. In this case, a pair of terminal patterns are provided on the surface of the insulating plate 122 to form electrical connections with the respective electrodes of the LED chip, thereby forming lead terminals. The insulating plate is formed with a hole for receiving the secondary mounting member so that the bottom surface of the secondary mounting member is in contact with the heat conductive plate. In this case, the heat conductive plate defines the bottom surface of the LED chip unit, and thus heat generated in the LED chip can be effectively conducted to the main body through the secondary mounting member 30 and the heat conductive plate 121, without being conducted through the circuit board 20. The secondary mounting member can alleviate stress acting on the LED chip due to a difference in linear thermal expansion coefficient between the LED chip and the heat conductive plate. Forming terminal patterns 123 constituting lead terminals of the LED chip on insulating plate 122 can lengthen the insulating distance between main body 90 and lead terminals 123a, 123b, and improve the reliability thereof.

Preferably, the terminal pattern 123 in the LED chip unit 1 is partially exposed on the surface of the insulating plate 122 to define an outer lead 123b, wherein the circuit pattern 22 of the circuit board 20 is electrically connected to the outer lead 123 at the periphery of the window 23.

Drawings

Fig. 1 is a schematic exploded perspective view of a main part (emergency part) according to a first embodiment;

fig. 2 is a schematic perspective view of a main part in the above embodiment;

fig. 3 is a schematic sectional view of a main portion in the above embodiment;

FIG. 4 is a partially cut-away schematic side view of the above embodiment;

fig. 5 is an exploded perspective view of a main part in the above embodiment;

fig. 6 is a schematic exploded perspective view of a main part according to a second embodiment;

fig. 7 is a schematic sectional view of a main portion in the above embodiment;

fig. 8 is a schematic exploded perspective view of a main part in the above embodiment;

fig. 9 is a schematic exploded perspective view of a main part according to a third embodiment;

fig. 10 is a schematic perspective view of a main part in the above embodiment;

fig. 11 is a schematic sectional view of a main portion in the above embodiment;

fig. 12 comprises a schematic front view (a) and a schematic bottom view (b) with parts cut away according to a fourth embodiment;

fig. 13 shows the main body in the above embodiment, wherein (a) is a top view and (b) is a cross-sectional view taken along line a-a' in (a);

fig. 14 shows the main body in the above embodiment, in which (a) is a partially cut-away sectional view and (b) is a plan view of a main portion;

fig. 15 is a perspective view of the main body in the above embodiment;

fig. 16 shows the light-transmitting member of the above-described embodiment, in which (a) is a top view, (b) is a partially cut-away sectional view, and (c) is a sectional view of a main portion;

fig. 17 shows another configuration example of the light-transmitting member in the above-described embodiment, in which (a) is a top view and (b) is a sectional view;

fig. 18 shows the decorative cover in the above embodiment, in which (a) is a plan view and (b) is a sectional view taken along a line a-a' in (a);

fig. 19 is a perspective view of the trim cover in the above embodiment;

fig. 20 is a schematic sectional view of the LED chip unit mounted to the main body in the above embodiment;

fig. 21 is an exploded perspective view of a main part in the above embodiment;

fig. 22 is a plan view of a main portion of the LED chip unit in the above embodiment;

fig. 23 is a perspective view of the secondary mounting member in the above embodiment;

fig. 24 shows the decorative panel in the above embodiment, wherein (a) is a plan view, (B) is a sectional view taken along line a-B-C-D in (a), (C) is a bottom view partially cut away;

fig. 25 shows the circuit board in the above embodiment, in which (a) is a top view and (b) is a bottom view;

fig. 26 shows a fifth embodiment in which (a) is a schematic perspective view and (b) is an enlarged view of a main part of (a);

FIG. 27 is a schematic exploded perspective view of the above embodiment;

FIG. 28 is a schematic perspective view of the sixth embodiment;

fig. 29 is an enlarged perspective view of a main part in the above embodiment; and

fig. 30 is a schematic exploded perspective view of the above embodiment.

Detailed Description

(first embodiment)

Hereinafter, the light emitting device of the present embodiment will be described with reference to fig. 1 to 5.

The light emitting device of the present embodiment is used as a spot light (spot light) or the like. The body 90 is made of metal, high thermal conductive metal such as Al and Cu, and is connected to the arm 112 by a binding screw (binding screen) 113. One end of the arm is fixed to a rotatable base 110 of the support base 100 by a rod screw (flush) 111.

The main body 90 is shaped as a bottomed cylinder (a bottomed cylindrical cylinder in the present embodiment), and has an open surface (front surface) to accommodate a plurality of LED chip units 1 (light emitting devices). In the present body 90, each LED chip unit 1 is mounted to the bottom wall 90a through an insulating layer 80 made of a printed circuit substrate (green sheet), and the surface of the opening is covered with a front cover 91. The front cover 91 includes: a disk-shaped light-transmitting plate 91a made of a glass plate; and an annular window frame 91b for supporting the light-transmitting plate 91a, the annular window frame 91b being connected to the main body 90. The insulating layer 80 contains a filler such as silica (silica), alumina, or the like, and is made of a thermosetting material having low viscosity upon heating such as a resin plate (for example, an organic printed circuit substrate such as an epoxy resin plate highly filled with a filler containing fused quartz), exhibiting high electrical insulation and high thermal conductivity. Such a material has high fluidity when heated and adheres to the main body 90, thereby enabling the LED chip unit 1 to be firmly fixed to the main body 90. In addition, a non-sintered ceramic member formed into, for example, a green sheet may be used as the insulating layer 80. The material of the light-transmitting plate 91a is not limited to a glass plate, but may be a light-transmitting material, and the light-transmitting plate 91a is integrally formed with a plurality of lenses that control the orientation of light emitted from the respective LED chip units 1.

The respective LED chip units 1 are disposed inside the main body 90 and electrically connected through the circuit board 20 in the main body 90. The outer periphery of the circuit board 20 is shaped into a partially cut circle having a linear portion.

The circuit board 20 includes a glass epoxy plate formed thereon, which has a circuit pattern 22 for supplying power to each LED chip unit 1. A plurality of rectangular windows 23 extend through the thickness direction of the circuit board to respectively receive the LED chips therein. In the present embodiment, the light-transmitting plate 91a forms a light-transmitting member for passing the visible light emitted from each LED chip unit 1, and is disposed away from one surface of the circuit board 20 away from the main body 90.

The circuit pattern 22 of the circuit board 20 is designed to connect a plurality of LED chip units 1 in parallel with each other. A power supply cable (not shown) including a plurality of wires is connected to both ends of the parallel circuit of the LED chip units 1, for example, by soldering or the like, and extends through a wire insertion hole 90c formed at the bottom wall 90a of the main body 90 to supply power from a power supply circuit (not shown) to the parallel circuit of the LED chip units 1. The power supply circuit includes a rectifier circuit (rectifier circuit), the rectifier circuit including: a diode-bridge (diode-bridge) for rectifying Alternating Current (AC) output from an alternating current power supply such as a commercial power supply; and a smoothing capacitor (smoothing capacitor) for smoothing an output of the rectifying circuit. Although the present embodiment shows the case where the LED chip units 1 are connected in parallel within the main body 90, the present invention is not limited to such an electrical connection manner, but a series electrical connection or a series-parallel combination of the LED chip units may be employed.

The LED chip unit 1 includes: a rectangular plate-shaped LED chip 10; a chip mounting member 41 shaped as a rectangular plate larger than the LED chip 10 for supporting the LED chip 10; a reed-shaped lead terminal 42 integrally formed on one side edge of the chip mounting member 41; a T-shaped lead terminal 43 disposed away from the other side edge of the chip mounting member 41; a reflector (reflector)50 disposed around the LED chip 10 for reflecting light emitted from a side surface of the LED chip 10 toward a front side (upper side in fig. 3) of the LED chip 10; and a protective cover 60 connected to the front side of the reflector 50 so as to cover the LED chip 10.

The chip mounting member 41 and the respective lead terminals 42, 43 are formed of a lead frame including a metal plate (e.g., a copper plate). The chip mounting member 41 and the respective lead terminals 42, 43 are integrally formed with an insulating rectangular frame-shaped holding frame (holding frame)45 including synthetic resin so that the inner lead portions 42a, 43a and the outer lead portions 42b, 43b of the chip mounting member 41 are disposed inside and outside the holding frame 45, respectively. The above-described insulating layer 80 is interposed between the main body 90 and the lead frame including the chip mounting member 41 and the respective lead terminals 42, 43, thereby forming an electrically insulating and thermally conductive connection therebetween. The respective outer leads 42b, 43b of the lead terminals 42, 43 are electrically connected to the circuit pattern 22 of the circuit board 20 through bonding portions 95 formed by solder. In the present embodiment, the package (package) of the LED chip 10 includes a holding frame 45, a chip mounting member 41, respective lead terminals 42 and 43, a reflector 50, a protective cover 60, and an insulating layer 80. Further, in the present embodiment, the insulating layer 80 is provided for each of the chip units 1, but a plurality of LED chip units 1 may be mounted in common to one printed circuit substrate slightly smaller than the bottom wall 90a of the main body 90.

The material of the lead frame is not limited to copper, and phosphor bronze or the like may be used. Although the chip mounting member 41 and the respective lead terminals 42, 43 are integrally formed with the holding frame 45 in the present embodiment, the holding frame 45 is not always necessary, and the chip mounting member 41 need not be integrally formed with the lead terminals 42. However, in the case where the chip mounting member 41 is formed integrally with the lead terminals 42 and the holding frame 45 is provided, each LED chip unit 1 can be easily handled and individually inspected as a single component before being mounted to the main body 90.

The LED chip 10 is a blue light-emitting, gallium nitride (GaN) -based blue LED chip. The LED chip 10 includes a conductive plate 11 made of conductive n-type silicon carbide (SiC) having a lattice constant (lattice constant) and a crystal structure closer to GaN than sapphire (sapphire). On the main surface of the conductive plate 11, a light emitting part 12 is formed, which is made of a gallium nitride-based semiconductor material and is obtained by epitaxial growth (e.g., MOVPE process) so as to have a layered structure, such as a double heterostructure. A cathode electrode (n-type electrode) (not shown) is formed on the rear side of the conductive plate 11 as an electrode on the cathode side. An anode electrode (p-type electrode) (not shown) is formed on the surface of the light-emitting section 12 (the foremost surface of the theoretical surface of the conductive plate 11) as an electrode on the anode side. Although both the cathode electrode and the anode electrode are composed of a laminate of a nickel (Ni) film and a copper (Cu) film in the present embodiment, the material of the cathode electrode and the anode electrode is not particularly limited, and may be a material having good ohmic characteristics (e.g., Al, etc.).

In the present embodiment, one of the lead terminals 42 forms a cathode, and the other lead terminal 43 forms an anode. Further, the present embodiment shows: the LED chip 10 is mounted to the chip mounting member 41, wherein the light emitting portion 12 of the LED chip 10 is spaced farther from the chip mounting member 41 than the conductive plate 11. In consideration of the light extraction, it is desirable that the LED chip 10 is mounted to the chip mounting member 41 and the light emitting portion 12 of the LED chip 10 is spaced farther from the chip mounting member 41 than from the conductive plate 11, as shown in the present embodiment. However, since the conductive plate 11 has almost the same refractive index as the light emitting portion 12, the light extraction loss does not increase significantly. Therefore, the LED chip 10 can be mounted to the chip mounting member 41 with the light emitting portion 12 of the LED chip 10 being spaced closer to the chip mounting member 41 than to the conductive plate 11.

The reflector 50 is shaped like a frame to have an opening area that becomes larger as the reflector 50 is apart from the LED chip 10 along the thickness direction of the LED chip 10. The fixing members 55 are made of an insulating sheet-like adhesive film to fix the reflector 50 to the respective lead terminals 42, 43. Note that the reflector 50 and the fixing member 55 are respectively formed to have a rectangular outer peripheral shape slightly smaller than the inner peripheral shape of the holding frame 45.

The reflector 50 may be made of a material (e.g., Al, etc.) having a large reflectance to light from the LED chip 10 (i.e., blue light in the present embodiment). The fixing member 55 is formed with a circular opening 55a for receiving the opening of the reflector 50. In addition, it is preferable to enclose (pot) a transparent encapsulating resin such as silicone resin or the like inside the reflector 50 to form an encapsulating member for encapsulating the LED chip 10.

The protective cover 60 has: a dome-shaped cover member 62 provided centrally on a center line passing along the thickness direction of the LED chip 10; and a flange 61 provided to extend laterally from the periphery of the opening portion of the dome-shaped cover member 62. The periphery of the surface of the flange 61 opposite to the reflector 50 is provided with an annular rib 61a for firmly positioning the protective cover 60 to the reflector 50. The protective cover 60 must be connected to the reflector 50 by an adhesive such as silicone, epoxy, or the like.

The protective cover 60 is molded from a mixture of a transparent material such as silicone resin and a particulate yellowish fluorescent material that is excited by blue light from the LED chip 10 to emit a broad-band yellowish light. In the LED chip unit 1 of the present embodiment, the protective cover 60 also functions as a color conversion member that is excited by light from the LED chip 10 to emit light of a color different from the light emission color of the LED chip 10, and outputs white light by combining blue light from the LED chip 10 and light from the yellowish fluorescent material as the entire LED chip unit 1. As a material constituting the protective cover 60, the transparent material is not limited to silicone resin, and may be one such as acrylic resin, epoxy resin, and glass. In addition, the fluorescent material mixed with the transparent material constituting the protective cover 60 is not limited to the yellowish fluorescent material. For example, white light can be obtained by a mixture of other fluorescent materials such as a reddish fluorescent material and a greenish fluorescent material. Further, when each of the LED chips 10 emits light of a desired color of the LED chip unit 1, it is not necessary to mix a fluorescent material with a transparent material.

Although the present invention uses a blue LED chip emitting blue light as the LED chip 10 and a silicon carbide plate as the conductive plate 11, a gallium nitride plate may be used instead of the silicon carbide plate. As shown in table 1 below and disclosed in japanese laid-open patent publication No. 2003-168829, using a silicon carbide plate and a gallium nitride plate as the crystal growth plate can improve the thermal conductivity and reduce the thermal resistance thereof, as compared with using an insulating sapphire plate (dielectric sapphire plate) as the crystal growth plate. Further, the emission color of the LED chip 10 is not limited to blue, and may be red, green, or the like. That is, the material constituting the light emitting portion 12 of the LED chip 10 is not limited to the gallium nitride-based compound semiconductor material, but may be a gallium arsenide-based compound semiconductor material, a gallium phosphide-based compound semiconductor material, or the like, depending on the light emission color of the LED chip 10. The conductive plate 11 is not limited to a silicon carbide plate, and may be optionally selected from a gallium arsenide plate, a gallium phosphide plate, and the like, depending on the material constituting the light emitting section 12.

TABLE 1

Crystal growth plate	Thermal conductivity [ W/m.K ]	Coefficient of linear thermal expansion [ x 10%-6/K】	Thermal resistance (K/W)
				6H-SiC	350	4.2	0.857
GaN	130	5.59	2.308
				GaP	110	4.65	2.727
GaAs	54	5.9	5.556
				Sapphire	42	5.3	7.143

Table 1 shows experimental thermal resistance values measured when heat conduction is conducted in the thickness direction of a crystal growth plate having a thickness of 0.3mm and a cross-sectional area perpendicular to the thickness of 1mm²。

The LED chip 10 is mounted to the chip mounting member 41 with the sub-mount member 30 of a rectangular plate shape interposed between the LED chip 10 and the chip mounting member 41. The secondary mounting member 30 is larger in size than the LED chip 10, and the secondary mounting member 30 not only relieves stress applied to the LED chip 10 due to a difference in linear expansion coefficient between the LED chip 10 and the chip mounting member 41, which also serves as a heat conductive plate, but also conducts heat generated in the LED chip 10 to the chip mounting member 41 so as to transfer the heat over a wider area than that of the LED chip 10. It is desirable that the surface area of the chip mounting member 41 opposed to the LED chip 10 is sufficiently larger than the surface area of the LED chip 10 opposed to the chip mounting member 41. Preferably, the contact area is increased in order to reduce the thermal conductivity between the chip mounting member 41 and the insulating layer 80, thereby conducting uniformly over a wide area, enabling efficient heat dissipation from the LED chip 10. For 0.3mm²-1.0mm²In the LED chip 10 of (1), the surface area of the chip mounting member 41 facing the LED chip 10 is preferably 10 times or more larger than the surface area of the LED chip 10 facing the chip mounting member 41. Here, the secondary mounting member 30 is required to relieve the stress. When the secondary mounting member 30 meets this requirement, the secondary mounting member 30 must be thin, or made of a material of higher thermal conductivity, in order to reduce the thermal resistance.

In the present embodiment, tungsten copper (CuW) is used as a material constituting the secondary mounting member 30. The LED chip 10 is provided with: a cathode electrode electrically connected to the inner lead portion 42a of one lead terminal 42 through the secondary mounting member 30 and the chip mounting member 41; and an anode electrode electrically connected to the inner lead portion 43a of the other lead terminal 43 through a bonding wire 14 made of a thin metal wire (e.g., a thin gold wire, a thin Al wire, etc.). The circuit pattern 22 is electrically connected to the respective outer lead portions 42b, 43b of the lead terminals 42, 43 through bonding portions 95 formed of solder.

The material of the sub-mount member 30 is not limited to tungsten copper, but may be a material having a linear thermal expansion coefficient relatively close to that of the conductive plate 11 made of 6H — SiC and a high thermal conductivity, such as W, AlN, complex silicon carbide (complex SiC), silicon, or the like, as listed in table 2 below. However, when an insulator such as AlN or composite silicon carbide is used for the secondary mounting member 30, a conductive pattern needs to be provided on the surface of the secondary mounting member 30 facing the LED chip 10 for bonding the anode electrode, and needs to be electrically connected to the inner lead portion 42a of one lead terminal 42 with a bonding wire.

TABLE 2

Here, when Cu is used as the material of the chip mounting member 41, the secondary mounting member 30 is manufactured using CuW or W so as to directly bond the secondary mounting member 30 to the chip mounting member 41, which makes it possible to increase the bonding area between the secondary mounting member 30 and the chip mounting member 41 and reduce the thermal resistance therebetween, as shown in table 3 below, compared to when soldering is performed between the secondary mounting member 30 and the chip mounting member 41. Note that the solder used for bonding the LED chip 10 to the secondary mounting member 30 is made of a lead-free material such as AuSn, SnAgCu, or the like.

TABLE 3

	Soldering	Direct bonding
			Bonding area	60％-80％	Approximately 100 percent
Bonding strength	98N/mm2Or larger	127N/mm2Or larger
			Shear strength	98N/mm2	127N/mm2
Binding moieties	Flux may remain thereon

In addition, the sub-mount member 30 can be manufactured using W so as to be directly bonded to the chip-mount member 41, which enables to increase thermal conductivity and to reduce thermal resistance as compared with bonding using silver solder, as shown in table 4 below. When the material of the chip mounting member 41 is Cu and the material of the sub-mount member 30 is selected from AlN, composite silicon carbide, and the like, the solder is substantially made of a lead-free material such as AuSn, SnAgCu, and the like, to bond the chip mounting member 41 to the sub-mount member 30.

	Silver soldering	Direct bonding
			Thermal conductivity [ W/m.K ]	185.4	211.8

In the present embodiment, the lighting device using the LED is provided with a mirror 24 on the surface of the circuit board 20 opposite to the light-transmitting plate 91a, the mirror 24 being formed of a reflective film (e.g., a metal film such as an Al film) that reflects visible light. Since the mirror 24 reflects the visible light totally reflected by the light-transmitting plate 91a after being emitted from each LED chip unit 1 on the mirror 24, the mirror 24 can improve the light output compared to a device in which the mirror 24 is not provided. Here, the circuit pattern 22 and the mirror 24 are provided on the surface of the circuit board 20 facing the transparent plate 91a, respectively, and the degree of freedom in designing the circuit pattern 22 is improved. This enables optional selection of the materials of the circuit pattern 22 and the mirror 24, so that the light output can be further improved by selecting a material of high reflectance for the mirror 24. For example, using Al as the material for the mirror 24 provides a higher reflectivity of light in the visible region and a higher light output than using Ni as the material for the mirror. Although Au is employed as the material of the circuit pattern 22 in the present embodiment, the material of the circuit pattern 22 is not limited to Au, but may be Cu or the like.

In the lighting device with LEDs of the above embodiment, the heat generated in each LED chip unit 1 can be conducted to the metal-made main body 90 through the insulating layer 80 such as the printed circuit board, but not through the circuit board. A conventional lighting device includes a circuit board thermally connected to a bottom portion of the lighting device with an insulating material interposed therebetween. Compared with the conventional lighting device, the present embodiment is configured to reduce the distance between the light emitting portion 12 of the LED chip 10 and the main body 90 and to reduce the thermal resistance therebetween to enhance the thermal conduction performance, so as to reduce the rise in the junction temperature of the light emitting portion 12, thereby allowing the input power to be increased to achieve high light output. In addition, the lighting device of the present invention can suppress an increase in the junction temperature of the LED chip 10 and extend the life span of the LED chip 10 under the same light output power as compared with the conventional lighting device having an LED.

Further, the lighting device does not require a metal plate (metal-based printed circuit board) used in the conventional design as the circuit board 20, so that a circuit board less expensive than the metal circuit board 20, such as a glass epoxy board, can be employed in order to reduce the cost of the circuit board 20.

When the difference in the linear thermal expansion coefficient between the LED chip 10 and the chip mounting member 41 is small, the sub-mounting member 30 does not need to be interposed between the LED chip 10 and the chip mounting member 41. The lighting device without the sub-mount member can shorten the distance between the LED chip 10 and the bottom wall 90a of the main body 90 made of metal, reduce the thermal resistance between the light emitting portion 12 of the LED chip 10 and the main body 90, thereby improving the heat conduction performance thereof to achieve higher light output.

(second embodiment)

The configuration of the lighting device with LEDs of this embodiment is substantially the same as that of the first embodiment. As shown in fig. 6 to 8, the LED chip unit 1 in the present embodiment is different from the LED chip unit 1 in the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and repeated description is not necessary. Similar to the first embodiment, a front cover 91 (see fig. 4) is provided in this embodiment.

In the present embodiment, instead of the chip mounting member 41, the respective lead terminals 42, 43, and the holding frame 45 in the first embodiment, a mounting plate (chip mounting member) 70 is used, the mounting plate 70 including: a rectangular plate-shaped conductive plate 71 on the surface of which the LED chip 10 is carried; and an insulating film 72 stacked on the conductive plate 71, and patterned lead terminals 73, 73 are formed on a surface of the insulating film 72, respectively, for connection with the anode electrode and the cathode electrode of the LED chip 10. The conductive plate 71 is disposed between the sub-mount member 30 carrying the LED chip 10 and the insulating layer 80 mounted on the bottom wall 90a of the main body 90. The conductive plate 71 is basically made of a material having a high thermal conductivity such as copper, phosphor bronze, or the like. The material of the lead terminals 73, 73 may be copper or the like. The thickness of the material of the conductive plate 71 needs to be almost the same as that of the lead frame on which the LED chip 10 is mounted, and thus the thickness dimension can be reduced as compared with the thickness of the circuit board in the LED unit disclosed in the related art.

In the present embodiment, the mounting unit 51 is formed integrally with the reflector 50 to receive an annular positioning rib 61a extending from the flange 61 of the protective cover 60 to enable the protective cover to be securely positioned relative to the reflector 50.

Further, in the present embodiment, an anode electrode (not shown) located on one surface (top surface in fig. 7) of the LED chip 10 is electrically connected to one end (inner lead portion) of one lead terminal 73 through a bonding wire 14, a cathode electrode (not shown) located on the other side (bottom surface in fig. 7) of the LED chip 10 is electrically connected to one end (inner lead portion) of the other lead terminal 73 through a bonding wire 14, and the other end of each lead terminal 73 is electrically connected to the circuit pattern 22 of the circuit board 20 through a bonding portion 95 formed of solder. In the present embodiment, the package of the LED chip 10 includes a chip mounting member 70, a reflector 50, and a protective cover 60.

Compared with the prior art, the lighting device with LEDs in the present embodiment can reduce the thermal resistance between the light emitting portion 12 of the LED chip 10 and the main body 90, enhance the thermal conductivity, and suppress the rise of the junction temperature of the LED chip 10, similarly to the first embodiment. This configuration allows the input electric power to be increased to achieve a high light output. The cost of the circuit board 20 can be reduced by using a circuit board that is less expensive than a metal plate, such as a glass epoxy plate or the like.

When the difference in the linear thermal expansion coefficient between the LED chip 10 and the conductive plate 71 is small, the sub-mount member 30 does not need to be interposed between the LED chip 10 and the conductive plate 71 of the chip mount member 70. The lighting device without the sub-mount member 30 can shorten the distance between the LED chip 10 and the bottom wall 90a of the main body 90 made of metal, reduce the thermal resistance between the light emitting portion 12 of the LED chip 10 and the main body 90, and thereby improve the heat conduction performance thereof to achieve higher light output.

The present embodiment also enables each LED chip unit 1 to be easily handled and individually inspected as a single component before being mounted to the main body 90.

(third embodiment)

The configuration of the lighting device with LEDs of the present embodiment is almost the same as that of the first embodiment. As shown in fig. 9 to 11, the configuration of the circuit board 20 in the present embodiment is different from that in the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and repeated description is not necessary. Similar to the first embodiment, a front cover 91 (see fig. 4) is provided in this embodiment.

In this embodiment, the circuit pattern 22 extends from one surface of the circuit board 20 to the other surface of the circuit board 20 opposite to the light-transmitting plate 91a (see fig. 4) through the periphery of the window 23 so as to form bonding areas 95 on the periphery of the window 23, and the circuit pattern 22 is electrically connected to the conductive terminals 42, 43 of the LED chip unit at the bonding areas 95 by a bonding material such as solder.

The light emitting device with LEDs of this embodiment can be formed to increase the area of the mirror 24 on the surface of the circuit board 20 facing the light-transmitting plate 91a, compared to the first embodiment, so that high light output can be further enhanced. The circuit board 20 of the second embodiment may be replaced with the circuit board 20 of the present embodiment.

(fourth embodiment)

Now, a light emitting device with an LED of the present embodiment will be described with reference to fig. 12 to 25. The same components as those in the first embodiment are denoted by the same reference numerals, and repeated description is not necessary.

The lighting device with LEDs in this embodiment is a ceiling lamp (ceiling lamp) comprising a body 190 made of metal (e.g. a metal with high thermal conductivity such as Al, Cu) and connected to a support material 180 such as a ceiling structure. As shown in fig. 12 to 15, the main body 190 is formed in a disc shape, and a circular open recess (receive) 191 is provided on a surface (a bottom surface of (a) in fig. 12) of the main body 190 away from the support material 180. The recess 191 has a recess 192 at its inner bottom surface for accommodating a plurality of (8 in this embodiment) LED chip units 1 and a circular plate-shaped circuit board 20. Here, the circuit board 20 is formed with a plurality of (8 in the present embodiment) circular windows 23 (see fig. 25) for partially accommodating the respective LED chip units 1. The circuit board 20 is formed with a circuit pattern 22 (see (a) in fig. 25) so as to supply power to the LED chip units 1 on the surface of the circuit board 20 opposite to the inner bottom surface of the recess 192, and is disposed on the same side of the main body 190 as the respective LED chip units 1. The circuit pattern 22 in (a) in fig. 25 is formed to be connected in series with eight LED chip units 1.

The body 190 is formed at the center of the other face thereof (the top face in fig. 12 (a)) with a cylindrical buried portion 193, and the buried portion 193 protrudes from the body 190 to be inserted into the circular connection hole 181 in the support material 180. The main body 190 is provided with a wire insertion hole 194, and the wire insertion hole 194 extends from the center of the front edge surface of the buried part 193 and the inner bottom surface of the recess 192. The wire insertion hole 194 can guide the power supply cables 96, 96 for supplying power to the circuit board 20 into the recess 192. In other words, the wire insertion hole 194 is formed at the bottom of the recess 192 of the main body 190. To receive power from another power supply unit (not shown), a second connector 97 is detachably connected to the first connector at an end portion on the opposite side of the first connector from the respective power supply cables 96, 96 leading to the circuit board 20.

A pair of power-feeding through-holes 26, 26 (see fig. 25) are formed at the center of the circuit board 20 to be electrically connected with the power-feeding cables 96, 96. Each of the power feeding through holes 26, 26 is formed such that the inner surface and the periphery thereof are covered so as to connect the power feeding cables 96, 96 with solder. This construction eliminates the need to construct space for pulling the power supply cables 96, 96 within the recess 192 of the main body 190, thereby making the main body 190 thin. Each of the power supply through holes 26, 26 is electrically connected to the circuit pattern 22 on the surface of the circuit board 20.

Now, the LED chip unit 1 will be described with reference to fig. 20 to 24.

The LED chip unit 1 includes: an LED chip 10; a mounting board 120 on which the LED chip 10 is mounted; a frame body 140 disposed to surround the LED chip 10 on the same side of the mounting board 120 that supports the LED chip 10; bonding wires 14, 14 connected to the LED chip 10; an encapsulating member 150 formed of a light-transmitting material (encapsulating resin) for encapsulating the LED chip 10 and the bonding wires 14, 14 within the frame body 140; a lens 160 disposed to cover the encapsulation member 150 and the frame body 140; and a dome-shaped color conversion member 170 molded from a transparent material and a fluorescent material excited by light from the LED chip 10 to emit light of a color different from the emission color of the LED chip 10. The color conversion member 170 is disposed above the lens to form an air layer 180 between the light output surface 160b of the lens 160 and the outer surface of the frame 140.

The mounting board 120 includes a metal plate 121 and an insulating plate 122, and the insulating plate 122 is made of a glass epoxy (FR4) plate and is stacked on the metal plate 121. The insulating plate 122 is provided with a pair of terminal patterns 123, the pair of terminal patterns 123, 123 including conductive patterns electrically connected to respective electrodes of the LED chip 10. The insulating plate 122 is formed with a hole 124 at a portion thereof corresponding to the LED chip 10. Although Cu is employed as the material of the metal plate 121 in the present embodiment, the material of the metal plate 121 is not limited to copper, but may be a metal material having a higher thermal conductivity such as Al. In the LED chip unit 1 in this embodiment, the metal plate 121 forms a heat conductive plate made of a heat conductive material and supports the LED chip 10. The terminal patterns 123, 123 respectively form lead terminals electrically connected to the respective electrodes of the LED chip 10.

The insulating plate 122 is mounted on the metal plate 121 using a bonding metal layer 125 (see fig. 20 and 24), the bonding metal layer 125 being made of metal (Cu in the present embodiment) and formed on a surface of the insulating plate 122 opposite to the metal plate 121. Each of the lead patterns 123, 123 includes a laminate of a Cu film, a Ni film, and an Ag film. A barrier layer (resist layer)126 (see fig. 24) is made of whitish resin and is provided on the surface of the insulating plate 122 remote from the metal plate 121 so as to cover the respective lead patterns 123, 123. A circular window 126a is provided at the center of the barrier layer 126 for exposing the inner lead portions 123a, 123a of the lead patterns 123, 123; the periphery of the barrier layer is provided with circular windows 126b, 126b for exposing the respective outer lead portions 123b, 123b of these lead patterns 123, 123.

The LED chip 10 is mounted on the metal plate 121, and a rectangular plate-shaped sub-mount member 30 is interposed between the LED chip 10 and the metal plate 121. The secondary mounting member 30 is larger in size than the LED chip 10, and the secondary mounting member 30 not only relieves stress applied to the LED chip 10 due to a difference in linear expansion coefficient between the LED chip 10 and the metal plate (heat conductive plate) 121, but also conducts heat generated in the LED chip 10 to the metal plate 121 so as to transfer the heat over a wider area than that of the LED chip 10. In this embodiment, AlN is adopted as the material of the secondary mounting member 30 because AlN has high thermal conductivity and insulating properties. The surface of the sub-mount member 30 opposite to the LED chip 10 is provided with a cathode electrode electrically connected to one of the lead patterns 123 through a conductive pattern 31 (see fig. 23) and a bonding wire 14 composed of a fine metal wire 14 (e.g., a fine gold wire, a fine Al wire, etc.). The anode electrode is electrically connected to the other lead pattern 123 through the bonding wire 14. It should be noted that, in this connection, although the LED chip 10 and the secondary mounting member 30 may be connected by a solder such as SnPb, AuSn, SnAgCu or silver paste, they are preferably connected using a lead-free solder such as AuSn, SnAgCu. In addition, a reflection film 32 (such as a laminate of a Ni film and an Au film) is further provided at the periphery of the conductive pattern 31 of the secondary mounting member 30 so as to reflect light emitted from the LED chip 10.

The material of the sub-mount member 30 is not limited to AlN, and may be a material (for example, compound silicon carbide, silicon, or the like) whose linear thermal expansion coefficient is relatively close to that of the conductive plate 11 made of 6H — SiC and whose thermal conductivity is high. Since in the present embodiment, the LED chip 10 is mounted to the metal plate 121 and the sub-mount member 30 is interposed between the LED chip 10 and the metal plate 121, heat generated in the LED chip 10 can be efficiently radiated through the sub-mount member 30 and the metal plate 121 while enabling stress applied to the LED chip 10 due to a difference in linear expansion coefficient between the LED chip 10 and the metal plate 121 to be relieved.

In this embodiment, silicone resin is used as the light-transmitting material of the encapsulation member 150, but this material is not limited to silicone resin, and may be acrylic resin or the like.

The frame body 140 has a cylindrical shape and includes a molded article of transparent silicone resin, in which silicone resin is used as the transparent resin for the molded article. That is, in the present embodiment, the frame body 140 is formed of a light-transmitting material having almost the same linear thermal expansion coefficient as that of the material of the encapsulation member 150. In the present embodiment, a light-transmitting material constituting the package member 150 is enclosed in the frame body 140, and then thermally cured to form the package member 150, and then the frame body 140 is fixed to the mounting board 120. When acrylic is used as the light transmitting material of the encapsulation member 150 instead of silicone, the frame body 140 is preferably formed of a molded product of acrylic. The frame body 140 is preferably disposed on one surface of the insulating plate 122 remote from the metal plate 121 so as to surround the LED chip 10 and the sub-mount member 30.

The lens 160 is shaped as a biconvex lens so as to have a light output surface 160b of a convex shape and a light input surface 160a opposite to the encapsulation member 150. Although the lens 160 includes a molded product of silicone resin and has the same refractive index as the encapsulation member 150 in this embodiment, the lens 160 is not limited to the molded product of silicone resin, but may be a molded product of acrylic resin.

The light output surface 160b of the lens 160 is formed as a convex surface to prevent the interface between the light output surface 160b and the air layer 180 from totally reflecting the light emitted from the light input surface 160 a. Here, the lens 160 is disposed such that its optical axis coincides with a line passing through the center of the light emitting portion 12 along the thickness direction of the LED chip 10. The present configuration allows light emitted from the LED chip 10 to pass through the color conversion member 170 without exciting or colliding with the fluorescent material inside the color conversion member 170, and then to propagate through the encapsulation member 150 and the air layer 180.

The color conversion member 170 is molded from a mixture of a transparent material (e.g., silicone) and a particulate yellowish fluorescent material. The fluorescent material is excited by blue light emitted from the LED chip 10 and then passing through the encapsulation member 150, and can emit light yellow light in a wide frequency band. The LED chip 1 in the present embodiment is configured to emit blue light from the LED chip 10 and light from the yellowish fluorescent material through the outer surface 170b of the color conversion member 170, so that white light can be obtained. As for the material constituting the color conversion member 170, the transparent material is not limited to silicone, but may be one such as acrylic, epoxy, and glass. In addition, the fluorescent material mixed with the transparent material of the color conversion member 170 is not limited to the yellowish fluorescent material. For example, white light can be obtained by a mixture of other fluorescent materials such as a reddish fluorescent material and a greenish fluorescent material.

The color conversion member 170 is formed to be fitted to the light output surface 160b of the lens 160 such that the inner surface 170a of the color conversion member 170 is spaced apart from the light output surface 160b of the lens 160 by an almost uniform distance, and the color conversion member 170 is configured to have a constant wall thickness over the entire surface. The color conversion member 170 may be fixed to the mounting board 122 at the periphery of the open side thereof by an adhesive (e.g., silicone, epoxy).

In the LED chip unit 1 in this embodiment, the sub-mount member 30 is shaped like a flat plate (plane-like) having a horizontal dimension larger than that of the LED chip 10, and the reflection film 32 is provided at the periphery of the conductive pattern 31, that is, at the bonding portion bonded to the LED chip 10. The reflective film 32 is configured to reflect light from the side surface of the LED chip 10, and the reflective film 32 has a thickness such that the bottom surface thereof is farther from the metal plate 121 than the edge of the color conversion member 170 opposite to the insulating plate 122, thereby preventing the insulating plate 122 from absorbing light emitted from the side surface of the LED chip 10, and thus enabling the light extraction efficiency of the device to be improved. Further, the reflection film 32 does not allow light emitted from the side surface of the LED chip 10 to propagate outward through the joint portion between the color conversion member 170 and the insulating plate 122, which suppresses color unevenness of the LED chip unit, thereby enabling enhancement of light output for improving light extraction efficiency of the device.

In this embodiment, the LED chip 10 is mounted at the center of the secondary mounting member 30 such that each side of the LED chip 10 perpendicularly intersects a diagonal line of the secondary mounting member 30 in a horizontal view, enabling the reflector 32 to effectively reflect light emitted from the side surface of the LED chip 10 toward the secondary mounting member 30, thereby enabling enhancement of light output for improving light extraction efficiency of the device. In the present embodiment, the LED chip 10 and the sub-mount member 30 are disposed to have a common central axis along the thickness direction, and respective diagonal lines of the LED chip 10 intersect with diagonal lines of the sub-mount member 30 at an angle of 45 degrees. In the present embodiment, as described above, since mounting board 120 includes the layered structure in which insulating plate 122 is stacked on metal plate 121, the insulating distance between main body 190 and lead terminals 123, 123 is lengthened, thereby improving the reliability thereof as compared to the first embodiment.

In the LED chip unit 1 of the present embodiment, since the air layer 180 is provided between the light output surface 160b of the lens 160 and the frame body 140 while the frame body 140 is brought out of close contact with the lens 160, the color conversion member 170 can surely avoid other yield reduction due to dimensional inaccuracy of the color conversion member 170 or positioning inaccuracy thereof. Further, in the LED chip unit 1 of this embodiment, the color conversion member 170 can surely avoid other yield reduction due to the dimensional inaccuracy of the color conversion member 170 or the positioning inaccuracy thereof. An air layer 180 is formed between the color conversion member 170 and the lens 160 to reduce the possibility of contact between the lens 160 and the color conversion member 170 deformed by an external force therein. The air layer protects the LED chip 10 and the respective bonding wires 14, 14 from stress generated in the color conversion member 170 in response to an external force and then transferred via the lens 160 and the encapsulation member 150, thereby improving reliability. In addition, since the air layer 180 is provided between the color conversion member 170 and the lens 160, it is possible to suppress moisture from the outside from being transmitted to the LED chip.

Since the air layer 180 exists between the color conversion member 170 and the lens 160, the lens 160 allows only a small portion of light, which is scattered from the yellowish fluorescent particles within the color conversion member 170 after being emitted from the LED chip 10 and then incident on the color conversion member 170 through the encapsulation member 150 and the lens 160, to pass through the lens 160, thereby improving the light extraction efficiency of the LED chip unit 1 as a whole.

Each LED chip unit 1 is mounted to the inner bottom surface of the recess 192 of the main body 190 through an insulating layer 80 made of a printed circuit substrate. The light emitting device with LEDs in this embodiment, like the other embodiments, can suppress the temperature rise of the LED chip 10, so that high light output can be achieved and the cost of the circuit board 20 can be reduced.

The window 23 of the circuit board 20 shown in fig. 25 is formed in a circular shape for accommodating the color conversion member 170 of the LED chip unit 1. The circuit board 20 is provided with a plurality of through holes 27 for electrically connecting the outer leads 123b and the circuit pattern 22 by a solder material such as solder on the periphery of each window 23 overlapping with the corresponding outer lead 123b of the LED chip unit 1. Each through hole 27 is formed such that: the inner surface of the hole extending in the thickness direction of the circuit board 20 and the peripheries thereof at both sides of the circuit board 20 are covered so as to connect the circuit patterns 22 on the circuit board 20. Similar to the second embodiment, the surface of the circuit board 20 opposite to the light-transmitting member 200 described below may be provided with a mirror 24 (see fig. 9) and a whitish barrier layer as a light reflection film.

The main body 190 includes a plurality of (two in this embodiment) coupling screw holes 195, and the coupling screw holes 195 extend from an inner bottom surface of the recess 191 to the other surface of the main body 190 to pass a plurality of (two in this embodiment) coupling screws 198, so that the main body 190 can be coupled to the support material 180, such as a ceiling structure, using the coupling screws 198.

The light-transmitting member 200 is disposed over a surface of the circuit board 20 away from the inner bottom surface of the recess 192 of the main body 190 for passing visible light from each LED chip unit 1.

The light-transmitting member 200 is formed of a molded product of a light-transmitting material (e.g., acrylic resin, etc.). The light-transmitting member 200 includes: a front plate portion 201 spaced apart from the circuit board 20; and an annular side plate portion 202 extending from the peripheral edge of the front plate portion 201 toward the inner bottom surface of the recess 191 of the main body 190, as shown in fig. 12 to 16. The main body 190 is formed with two fixing screw holes 197, and fixing screws 199 are inserted into the fixing screw holes 197 so as to fix the light transmitting member 200 to the main body 190. Two bosses (boss part)203 are formed integrally with the light transmitting member 200 and are provided with set screw holes 204 for receiving front edges of the set screws 199 inserted through the set screw holes 197 from the upper surface of the main body 190. The peripheral portion of the circuit board 20 is formed with a cutout portion 28 corresponding to the convex portion 203.

The light emitting device with LED of the present invention includes a decorative cover 210 for covering the periphery of the recess 192 on the main body 190 and the respective connection screws 198. The decorative cover 210 has a window 211 with a circular opening to expose the light output surface (the bottom surface in fig. 12 (a)) of the light transmissive member 200. The main body 190 is attached to the ceiling material 180 by the attachment screws 198 and then the trim cover 210 is fixed to the main body 190, so that the aesthetic appearance thereof can be improved since the attachment screws 198 are hidden behind the trim cover 210. Here, the trim cover 210 is formed of an elastic synthetic resin (e.g., PBT, ABS, etc.) and is provided with a plurality of engaging protrusions 212, the engaging protrusions 212 protruding from a surface of the trim cover 210 opposite to the main body 190 for engaging with a plurality of engaging holes 196 formed in the main body 190, respectively. In other words, the trim cover 210 can be connected to the main body 190 by engaging the plurality of engaging protrusions 212 to the plurality of engaging holes 196 of the main body 190, respectively.

Although the decorative cover 210 is formed of a molded product of synthetic resin, the decorative cover 210 may be made of metal in order to enhance heat conduction performance and to suppress an increase in junction temperature of the LED chip 10 (compared to a decorative cover made of synthetic resin). When the trim cover 210 is made of metal, it may be formed to be detachably mounted on the main body 190 using a plate spring, or fixed to the main body using screws.

In the light-transmitting member 200, the front plate portion 201 is formed as a flat plate, but may also be a molded article composed of a light-transmitting material (e.g., acrylic, glass, etc.) having a plurality of lenses 205, the lenses 205 being respectively provided at portions of the front plate portion opposed to the LED chip units 1 for controlling light emitted from the LED chip units 1, as shown in fig. 17. Here, each lens 205 is a fresnel lens, and is provided with a concave portion 206 for accommodating the color conversion member 170 of the LED chip unit 1. Each lens 205 is disposed so that its optical axis coincides with the optical axis of the lens 160 of the LED chip unit 1. Each lens 205 is capable of directing light emitted from an inner surface 206b of the recess 206 toward a light output surface 205a of the lens 205.

When the portion of the light-transmitting member other than the lens 205 is made of metal, such a configuration in fig. 17 can enhance the heat conduction performance and suppress the rise of the junction temperature of the LED chip 10, compared to when it is entirely made of a synthetic resin, glass, or the like.

(fifth embodiment)

As shown in fig. 26 and 27, the illumination device with LEDs of the present embodiment differs from the fourth embodiment in the shape of a metal-made body 290, and the configuration in the LED chip unit 1 of the present embodiment is the same as the fourth embodiment. The same components as those in the fourth embodiment are denoted by the same reference numerals, and repeated description thereof is not necessary.

The main body 290 in this embodiment is formed in a band plate shape (elongated rectangular plate shape) and includes a plurality of (eight in the illustrated example) LED chip units 1, and the recess 290a is for accommodating the band plate-shaped circuit board 20. Here, the plurality of LED chip units 1 are spaced apart by a predetermined interval in the longitudinal direction of the main body 290. Similarly to the fourth embodiment, each LED chip unit 1 is mounted to the inner bottom surface of the recess 290a of the main body 290 through an insulating layer 80 (see fig. 20) made of a printed circuit substrate or the like.

A circuit pattern (not shown) for connecting the LED chip units 1 in series is formed on a surface of the circuit board 20 opposite to the inner bottom surface of the recess 290a so as to be suitably connected with an electric wire (not shown) extending to the recess 290a through an insertion hole (not shown). It should be noted that, similarly to the fourth embodiment, the circuit board 20 is provided with a window 23 and two through holes 27 at portions thereof corresponding to the respective LED chip units 1.

The illumination device using LEDs of the present embodiment, similarly to the fourth embodiment, can also suppress temperature rise in the LED chip 10 for achieving high light output and reduce the cost of the circuit board 20. The circuit board 20 in the present embodiment is not limited to a glass epoxy board, but may be a board such as a flexible printed wiring board (FPC).

(sixth embodiment)

The basic configuration of the LED chip unit 1 of the illumination device with LEDs of the present embodiment is almost the same as that of the fifth embodiment. In the fifth embodiment, all the LED chip units are connected by one circuit board 20 within the main body 290, whereas in the present embodiment, all the LED chip units are connected by a plurality of circuit boards 20, as shown in fig. 28 to 30. In this embodiment, it should be noted that two LED chip units are provided for each of the circuit boards 20 connected in series along the longitudinal direction of the main body 290, wherein the adjacent LED chip units are electrically connected with a lead (not shown). The other configurations of the present embodiment are the same as those of the fourth embodiment, and repeated description is not necessary.

In other embodiments, one circuit board 20 may be replaced with a plurality of circuit boards in order to appropriately connect the LED chip units.

Although in the above embodiments, the glass epoxy board is exemplified as the circuit board 20, the circuit board 20 may be, for example, a ceramic MID board formed with a plurality of bumps at portions thereof not overlapping with the LED chip units, the bumps being in contact with the main body so as to further enhance the heat conductive property.

Claims (10)

1. A light emitting device with an LED, comprising:

a body made of metal;

a plurality of LED chip units, each of which includes an LED chip and a pair of lead terminals electrically connected to electrodes of the LED chip;

a circuit board formed with a circuit pattern, the circuit board configured to supply power to the respective LED chip units;

an insulating layer disposed between the main body and the plurality of LED chip units to form electrical insulation and thermal connection between the main body and the LED chip units; and

a chip mounting member for supporting the LED chip,

wherein the circuit board is formed with a plurality of windows through which the respective LED chip units extend, respectively, and the lead terminals are maintained in electrical contact with the circuit pattern at the periphery of the windows,

each LED chip unit is thermally connected with the main body through the insulating layer at the bottom surface of the LED chip unit,

a first one of the lead terminals is integrally formed on one side edge of the chip mounting member,

a second one of the lead terminals is disposed apart from the other side edge of the chip mounting member, and

the insulating layer is interposed between the main body and the chip mounting member and the corresponding lead terminals.

2. The light emitting device with LED of claim 1,

providing a light-transmitting member to pass visible light from each of the LED chip units; and

a mirror is formed on a top surface of the circuit board opposite to the light-transmitting member to reflect the visible light.

3. The light emitting device with LED of claim 2,

the circuit pattern and the mirror are formed on a top surface of the circuit board opposite to the light-transmitting member.

4. The light emitting device with LED of claim 2,

the circuit pattern is formed on a bottom surface of the circuit board.

5. The light emitting device with LED of claim 2,

the mirror is made of aluminum.

6. The light emitting device with LED of claim 1,

the body is formed in a disc shape, and has a recess on one face thereof for accommodating the LED chip unit and the circuit board therein; and

a wire insertion hole is provided at the center of the main body, extending through the bottom of the recess, for passing therethrough a power supply cable connected to the center of the circuit board.

7. The light emitting device with LED of claim 6,

the main body is formed at a portion thereof surrounding the recess with coupling screw holes for a plurality of coupling screws, respectively, for fixing the main body to a support material,

a frame-shaped decorative cover fitted to the main body so as to shield a periphery of the recess and the connection screw on one face of the main body, the decorative cover having a window through which a light output surface of the light transmitting member is exposed, and the decorative cover being made of metal.

8. The light emitting device with LED of any one of claims 1-7,

a plurality of lenses are formed at respective portions of the light-transmitting member opposite to the plurality of LED chip units for determining an orientation of light emitted from the plurality of LED chip units, and portions of the light-transmitting member other than the lenses are made of metal.

9. The light emitting device with LED of any one of claims 1-7,

each of the LED chip units includes:

a heat conductive plate made of a heat conductive material, and the LED chip is mounted to the heat conductive plate;

a secondary mounting member interposed between the LED chip and the heat conductive plate for relieving stress acting on the LED chip due to a difference in linear thermal expansion coefficient between the LED chip and the heat conductive plate; and

an insulating plate stacked on the heat conductive plate,

the lead terminals are formed of a terminal pattern including a conductive pattern disposed on a surface of the insulating plate remote from the heat conductive plate,

the insulating plate is formed with a hole that receives the secondary mounting member, the secondary mounting member being held in direct contact with the heat conductive plate,

the LED chip unit has a bottom surface defined by the heat conductive plate.

10. The light emitting device with LED of claim 1,

a portion of the terminal pattern is exposed on a surface of the insulating plate to define an outer lead electrically connected with the circuit pattern of the circuit board on a periphery of the window.