JP2012054181A - Led lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting device with enhancement of lighting function made easy through improvement of a heat dissipation structure of LEDs lit by a DC-DC converter.SOLUTION: The LED lighting device is provided with the LEDs 1, a lighting circuit 12 including a direct-current power source 2a for obtaining direct-current voltage by rectifying and smoothing alternating-current voltage and a DC-DC converter 2b containing a wideband gap semiconductor switching element and biasing the LEDs by operating at a switching frequency in an MHz region by inputting direct-current voltage obtained by the direct-current power source, and a common heat dissipation means 3 with the LEDs and the DC-DC converter arranged on the same surface side to cool them.

Description

  The present invention relates to an LED lighting device including a DC-DC converter that energizes an LED.

  By energizing the LED using a DC-DC converter, the LED can be lighted with high efficiency. When an LED is lit using an AC power supply via a DC-DC converter, the LED lighting circuit is mainly composed of a DC power supply and a DC-DC converter. The DC power source obtains a DC voltage obtained by rectifying and smoothing the AC voltage, and inputs the DC voltage to a DC-DC converter to convert the DC voltage into a desired DC voltage for lighting the LED by a switching operation.

  Since the LED has a high power density at the time of lighting, the heat generation density is high, and thus sufficient heat dissipation means is necessary. In addition, the DC-DC converter also needs to dissipate heat because its switching elements generate heat during operation. In the conventional LED lighting device, although the entire DC-DC converter is mounted on a wiring board and heat dissipation is taken into consideration, it is mounted together with a DC power source and arranged separately from the LED.

  A semiconductor element mainly composed of a semiconductor (wide band gap semiconductor) having a wide band gap such as SiC (silicon carbide), GaN (gallium nitride) and diamond has excellent high frequency switching characteristics and heat resistance, and is a Si power device. It has been attracting attention as having the potential to greatly exceed the performance limits of Therefore, expectations for wide gap semiconductor elements are also high in the field of power devices.

  Typical semiconductor elements using a wide band gap semiconductor, that is, wide band semiconductor switching elements include JFET (junction FET), SIT (electrostatic induction transistor), MESFET (metal-semiconductor FET: Metal-Semiconductor-Field-). Effect-Transistor), HFET (Heterojunction Field Effect Transistor), HEMT (High Electron Mobility Transistor), and storage FET.

  Wide bandgap semiconductor switching elements have excellent high-frequency switching characteristics and heat resistance as described above. By using this for a DC-DC converter, high-frequency operation is performed in the region of MHz or higher, so that the switching elements And it becomes possible to significantly reduce the size of LC parts.

Japanese Patent No. 4482706

  In the case of a wide band gap semiconductor switching element, the heat-resistant temperature is high as described above, and the heat generation density is increased as the size is reduced. On the other hand, a smoothing capacitor used for a DC power supply is generally an aluminum electrolytic capacitor having a large capacity, but has a characteristic that the lifetime is extended as the temperature is lower. In addition, when lighting an LED lighting device using a DC power supply and a DC-DC converter connected to an AC power supply, a fuse and a noise prevention circuit are attached to the DC power supply side for safety reasons. Therefore, there are few things with high heat-resistant temperature. Furthermore, when a control component such as a microcomputer for controlling light control or a remote control is attached, few of these components have a particularly high heat-resistant temperature.

  An object of the present invention is to provide an LED lighting device that improves the heat dissipation structure of an LED that is lit by a DC-DC converter and facilitates the improvement of the lighting function.

  According to the embodiment of the present invention, the LED lighting device includes the LED, the lighting circuit, and the heat dissipating means common to the LED and the DC-DC converter. The lighting circuit includes a DC power supply and a DC-DC converter. The DC power supply rectifies and smoothes the AC voltage to obtain a DC voltage. The DC-DC converter includes a wide band gap semiconductor switching element and operates at a switching frequency in the MHz region to light an LED. An LED and a DC-DC converter are arranged on the same surface side in the common heat radiation means.

  According to the present invention, a wide bandgap semiconductor switching element is used as a switching element of a DC-DC converter, and this is operated at a switching frequency in the MHz region, so that the DC-DC converter has a low switching loss and can be reduced in size and heightened. Since it is heat resistant, the DC-DC converter is arranged on the same side as the LED of the common heat dissipation means, so the heat dissipation means can be simplified and miniaturized, making it easier to improve the lighting function An LED lighting device can be provided.

It is sectional drawing of the LED lighting apparatus concerning the 1st Embodiment of this invention. It is a top view which similarly shows arrangement | positioning of LED and a DC-DC converter with respect to a LED board. It is a top view which shows the modification of arrangement | positioning of LED and DC-DC converter with respect to a LED board similarly. It is a circuit diagram similarly. It is the front view and sectional drawing of the LED lighting apparatus concerning the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail.

[First Embodiment]
As shown in FIG. 1, the first embodiment is a light bulb-type LED lamp in which an LED lighting device includes an LED 1, a lighting circuit 2, a heat dissipating unit 3, a translucent cover 4, and a power receiving unit 5.

  LED1 functions as a light source of the LED illumination device. Therefore, the light emission color of the LED 1 and the number of the LEDs used can be arbitrarily selected and arranged so as to ensure a desired light emission amount, color rendering property and light color as a light source. Moreover, when using several LED1, the aspect of those connection can be made into series connection, parallel connection, or series-parallel connection.

  Further, the LED 1 can be disposed on the heat radiation means 3 described later after being mounted on the LED substrate 11. As the LED substrate 11, it is preferable to use a substrate having a structure with good heat conduction to the heat radiation means 3. For example, a wiring board in which a heat conductive metal layer is laminated, for example, a wiring board using a heat conductive insulator such as aluminum nitride, and a thin sheet-like insulator are used as a base material and are attached to the heat radiation means 3 with a small thermal resistance. This includes wiring boards. In FIG. 1, reference numeral 11a denotes a through hole, which communicates with the through hole 3a of the heat radiating means 3 when bonded to the upper surface in the heat radiating means 3 described later.

  The lighting circuit 2 is circuit means for energizing and lighting the LED 1, and includes a DC power source 2a and a DC-DC converter 2b.

  The DC power source 2a is a circuit means for rectifying and smoothing an AC voltage to obtain a DC voltage and supplying the input power to a DC-DC converter 2b described later. In the present embodiment, the insulating case 12 is housed. The insulating case 12 has a power receiving means 5 attached to one end thereof. Further, since the DC-DC converter 2b is not housed in the insulating case 12, for example, the dimension in the tube axis direction can be reduced, and accordingly, the dimension in the tube axis direction of the heat radiating means 3 described later is shortened. be able to. The other end side of the insulating case 12 is fitted into a recessed portion 3c formed at the other end of the heat radiating means 3 to be described later, and is assembled with the heat radiating means 3 by being fixed with an adhesive, for example. . Note that a through hole 12 a is formed at the top of the insulating case 12.

  Further, the DC power supply 2a allows its constituent circuit components, such as a rectifier circuit and a smoothing capacitor, to be mounted on the wiring board 13. The component circuit parts may have relatively low heat resistance as described above, and since the thermal mass is small, the wiring board 13 should have a relatively low heat dissipation performance made of paper phenol or glass epoxy. Can be used. The input terminal of the DC power source 2a is connected to the power receiving unit 5. In addition, the output end of the DC power source 2a is connected to the input end of a DC-DC converter 2b disposed at a position away from the DC power source 2a via a conductive wire (not shown). In order to mount the component circuit components on the wiring board 13, it can be mounted by flow soldering and / or reflow soldering.

  The DC-DC converter 2b is a kind of switching power supply and is a means for converting DC power into desired DC power. As shown in FIG. 4, the DC-DC converter 2b uses a wide band gap semiconductor switching element Q1 as a switching element, operates at a switching frequency in the MHz region, and receives a DC voltage input from the DC power source 2a as desired. By converting to a DC voltage and outputting it, the LED 1 is energized and lit. The circuit configuration of the DC-DC converter 2b is not particularly limited, but a preferred example thereof will be described later.

  Further, the DC-DC converter 2b is disposed on the same surface side as the LED 1 in the common heat radiation means 3. Here, the phrase “the DC-DC converter 2b is disposed in the heat dissipation means 3” means that the main part including at least the wide band gap semiconductor switching element Q1 is disposed in the heat dissipation means 3. The main part is the most part of the power part of the DC-DC converter 2b. As the circuit parts constituting the power section, it is easy to select a circuit component having relatively high heat resistance like the wide band gap semiconductor switching element Q1, and the thermal mass during operation is relatively large. It is required to do.

  When the DC-DC converter 2b is a chopper, the wide band gap semiconductor switching element Q1, the diode D1 for flowing a reduced current flowing out from an inductor L1 described later to the second circuit B, and the wide band gap semiconductor switching element Q1 are used for off control. The constant current means Q2 constitutes a power part. These circuit components can be formed using a wide band gap semiconductor. Further, these circuit components can be constituted by one chip or multichip, and an integrated circuit having five connection pins can be configured.

  In addition, the inductor L1 used in the DC-DC converter 2b and the transformer instead thereof have a considerably small inductance value because the wide bandgap semiconductor switching element operates in the MHz region, preferably at a switching frequency of 1 MHz or more. Therefore, the inductor and the transformer can be miniaturized. For this reason, it becomes easy to print the coil on the LED substrate 11 to form the inductor L1 and the transformer. Further, the inductor L1 and the transformer can be formed thinly separately from the LED substrate 11, and can be solderlessly mounted on the LED substrate 11. If desired, the integrated circuit, inductor L1 or transformer and control means can be modularized and disposed in the heat dissipation means 3.

  Furthermore, when the DC-DC converter 2b is mounted on the LED substrate 11, it is preferable to employ a known solderless joining. Mounting using solder is not preferable because even if the heat resistance temperature of the circuit component is high, the heat resistance temperature is limited by the solder. Also, the lead contained in the solder has a large environmental impact, so we do not want to use it.

  FIG. 2 is a plan view of the LED substrate 11, in which the LED 1 and the DC-DC converter 2 b are mounted on the LED substrate 11. The LED 1 includes a plurality of LED chips connected in series, and is arranged in a ring shape on the peripheral side of these LED substrates 11. The arrangement of the LEDs 1 on the LED substrate 11 can be determined in consideration of both the light distribution and the good dispersion of the heat generation balance. On the other hand, the DC-DC converter 2b is arranged on the center side with respect to the position of the LED 1 on the LED substrate 11. That is, the arrangement of the DC-DC converter 2b can be determined mainly in consideration of a well-balanced distribution of heat generation and a marginal space of the LED substrate 11. Note that even if the mounting height of the DC-DC converter 2b is somewhat higher than that of the LED 1, since the LED 1 has a narrow light distribution angle of the LED chip, the light distribution characteristics of the LED lighting device are hardly adversely affected.

  FIG. 3 is a plan view showing a modification of the arrangement of the LED 1 and the DC-DC converter 2b with respect to the LED substrate 11. As shown in FIG. That is, the arrangement of the LED 1 and the DC-DC converter 2b is opposite to that in FIG. In FIG. 3, the LED 1 is disposed at a position close to the DC-DC converter 2b, but the adjacent heat-generating components are arranged so that the balance of heat distribution of the LED 1 and the DC-DC converter 2b is good. Needless to say, the intervals can be made uniform, for example, or the heat generation density when seen from the LED substrate 11 can be made uniform.

  The heat dissipation means 3 is mainly means for cooling the LED 1 and the DC-DC converter 2b. As shown in FIG. 1, the LED substrate 11 is supported on the upper surface thereof in close contact with the lower surface of the LED substrate 11 in close contact with the heat transfer relationship. In the illustrated embodiment, the contour shape of the outer peripheral surface is, for example, a cup shape.

  Further, the heat radiating means 3 is configured using a metal having high thermal conductivity, such as aluminum. In order to increase the heat radiation area of the heat radiation means 3, it is permitted to form a large number of heat radiation fins, for example, by die casting. In FIG. 1, a plurality of radiating fins extend in a direction parallel to the drawing and are formed in parallel in a direction perpendicular to the drawing. That is, in FIG. 1, the cross section of the heat radiation means 3 shows the cross section of the cylindrical part which forms the fin located in the center and the through-hole 3a. The through hole 3a extends in the direction of the tube axis and is formed at a position eccentric to the tube axis. The upper end is the through hole 11a of the LED board 11, and the lower end is the insulating case 12. The communication holes 12a communicate with each other.

  Furthermore, the heat dissipating means 3 has a standing edge 3b around the upper end portion in the figure. A translucent cover 4 (to be described later) is fixed to the heat radiating means 3 by, for example, bonding using the rising edge 3b.

  Then, the output of the DC power source 2a is led out from the through hole 12a of the insulating case 12 by, for example, an insulation-coated conductive wire (not shown), and the through hole 3a of the heat radiation means 3 and the through hole 11a of the LED substrate 11 Each of them extends through and is connected to the input end of the DC-DC converter 2b. As a result, when the AC power source is connected to the DC power source 2a via the power receiving means 5, the lighting circuit 2 is activated and the LED 1 is energized to light up.

  The translucent cover 4 is a means for mechanically protecting the LED 1 and, if desired, imparting a desired light distribution characteristic to the light emission of the LED 1 as an LED illumination device. In the present embodiment, the translucent cover 4 is substantially hemispherical and has light diffusibility. This can be realized by simplifying the size of the insulating case 12 and the heat radiating means 3 in the tube axis direction, and as a result, sufficient light diffusibility can be obtained, and the light distribution characteristics are improved. Become good.

  Further, the translucent cover 4 is formed with a peripheral step 4a at the opening end thereof. Then, the circumferential step 4a is fitted inside the rising edge 3b of the heat dissipation means 3, and is fixed to the inner surface of the circumferential step 4a with, for example, an adhesive, so that the translucent cover 4 includes the LED 1. Are integrally attached to the heat radiation means 3.

  In the present embodiment, the power receiving means 5 is formed of a screw cap. The insulating case 12 is fixed to one end portion exposed to the outside from the heat radiation means 3. The power receiving means 5 is connected to input terminals t1 and t2 (described later) of the DC power supply 2a of the lighting circuit 2 housed in the insulating case 12.

  FIG. 4 shows an example of the lighting circuit 2 that can be employed in the present embodiment. That is, the lighting circuit 2 includes the DC power supply 2a and the DC-DC converter 2b as described above, and the DC-DC converter 2b includes, for example, a step-down chopper, a step-up chopper, a step-up / step-down chopper, a flyback converter, and a forward converter. Various known circuit systems can be employed. As an example, FIG. 4 shows a step-down chopper.

  The DC power supply 2a is a circuit means for obtaining a DC voltage by rectifying and smoothing an AC voltage via a power receiving means. In the illustrated embodiment, the input terminals t1, t2, a current fuse F1, a noise prevention circuit NF, a rectifier A circuit DB1, a smoothing capacitor C1, and output terminals t3 and t4 are provided.

  The input terminals t1 and t2 are connected to the AC power source AC through the power receiving means 5. The current fuse F1 is blown when an input current exceeds a predetermined value and protects the lighting circuit 2. The noise prevention circuit NF is circuit means for filtering high frequency noise generated from the DC-DC converter 2b so as not to leak to the AC power supply side, and is connected between the current fuse F1 and the rectifier circuit DB1. The high-frequency bypass capacitor C2 and the common mode choke coil T1 are included. The rectifier circuit DB1 is a bridge-type full-wave rectifier circuit, and full-wave rectifies an AC voltage. The smoothing capacitor C1 is connected in parallel to the DC output terminal of the rectifier circuit DB1 to reduce DC voltage ripple. The output terminals t3 and t4 are connected to both ends of the smoothing capacitor C1, and output a smoothed DC voltage.

  In the DC-DC converter 2b, a step-down chopper is configured with input terminals t5 and t6, a wide band gap semiconductor switching element Q1, a constant current means Q2, an inductor L1, a diode D1 and an output capacitor C3 as main components. That is, output terminal t3 (positive electrode) of series power supply 2a, conductive line l1, input terminal t5, wide band gap semiconductor switching element Q1, constant current means Q2, output capacitor C3, inductor L1, input terminal t6, conductive line l2, and direct current The first circuit A composed of a series circuit of the output terminal t4 (negative electrode) of the power source 2a and the second circuit B composed of a closed circuit of the inductor L1, the diode D1 and the output capacitor C3 form a main circuit of the power circuit. ing. In FIG. 1, the conductive wires l1 and l2 extend through the through hole 12a of the insulating case 12, the through hole 3a of the heat dissipating means 3, and the through hole 11a of the LED substrate 11, and the DC power source 2a and The DC-DC converter 2b is conductively connected.

  Further, output ends t7 and t8 of the DC-DC converter 2b are disposed at both ends of the output capacitor C3.

  Further, as a control circuit, the drive circuit of the wide band gap semiconductor switching element Q1 is configured by a series circuit of a drive winding DW and a coupling capacitor C4 that are magnetically coupled to the inductor L1. In this drive circuit, an output capacitor C3 and a constant current means Q2 are connected in series between the gate and the source of the wide band gap semiconductor switching element Q1. Further, the constant current value variable circuit of the constant current means Q2 is constituted by a series circuit of a variable potential source E1 and a resistor R1. This constant current value variable circuit is connected between the gate and source of the constant current means Q2 via the output capacitor C3.

  Further, a gate protection circuit is connected between the gate and the source of each of the wide band gap semiconductor switching element Q1 and the constant current means Q2. This gate protection circuit is formed by connecting an anti-parallel circuit of a pair of diodes D2, D3 and D4, D5 so as to prevent an excessive voltage from being applied between the gate and the source. A high frequency bypass capacitor C5 is connected between the input terminals t5 and t6.

  As long as the wide band gap semiconductor switching element Q1 used in the main circuit of the power circuit of the DC-DC converter 2b is a switching element using a wide band gap semiconductor, the specific substance of the semiconductor is not particularly limited. For example, it may be a switching element mainly composed of a semiconductor (wide band gap semiconductor) having a wide band gap such as SiC (silicon carbide), GaN (gallium nitride) and diamond. The constant current means Q2 is the same as described above.

  In the illustrated embodiment, the wide band gap semiconductor switching element Q1 employs a switching element made of GaN-HEMT composed mainly of GaN. The wide band gap semiconductor switching element Q1 is characterized in that it is remarkably miniaturized and switching loss is remarkably reduced by switching it in the MHz region. The constant current means Q2 is the same as described above. The constant current means Q2 is the same as described above.

  The wide band gap semiconductor switching element Q1 includes a normally-on type and a normally-off type, and any of them may be used. In the case of the normally-on type, the gate potential can be turned off by making it negative with respect to the source potential. In the case of a normally-off type, the gate potential can be turned on by setting it to a positive potential with respect to the source potential. In the present embodiment shown in FIG. 4, the wide band gap semiconductor switching element Q1 is a normally-on type.

  The LED 1 is connected between the output ends t7 and t8 of the DC-DC converter 2b of the lighting circuit 2.

  Next, the circuit operation in the first embodiment will be described.

  When the DC power supply 2a is turned on, the wide bandgap semiconductor switching element Q1 of the DC-DC converter 2b is turned on because it is normally on, so the wide bandgap semiconductor switching element Q1, the constant current means Q2 from the DC power supply 2a The increased current begins to flow in the first circuit A via, and the current increases linearly. As a result, electromagnetic energy is accumulated in the inductor L1. Note that the gate-source voltage of the switching element Q1 is 0 during the period when the wide band gap semiconductor switching element Q1 is on. When the increasing current reaches the constant current value of the constant current means Q2, the increasing tendency of the current is stopped and held at the constant current. Note that while the increasing current flows in the inductor L1, the terminal voltage of the inductor L1 is positive.

  When the increased current reaches the constant current value of the constant current means Q2, the current flowing through the inductor L1 further increases, so the voltage of the constant current means Q2 increases in a pulse shape. Along with this, the source potential of the wide band gap semiconductor switching element Q1 becomes higher than the gate potential, and as a result, the gate becomes relatively clearly a negative potential, so that the wide band gap semiconductor switching element Q1 is turned off. For this reason, the increased current flowing into the inductor L1 is cut off by the switching element Q1 being turned off.

  At the same time when the wide band gap semiconductor switching element Q1 is turned off, the electromagnetic energy accumulated in the inductor L1 is released, and the reduced current flows out from the inductor L1 in the second circuit B with the same polarity as the increased current. While the reduced current is flowing, the voltage polarity of the inductor L1 is inverted and becomes negative, and the drive winding DW is induced with a voltage at which the gate of the wide band gap semiconductor switching element Q1 becomes a negative potential, Since the negative voltage is applied between the gate and source of the wide band gap semiconductor switching element Q1 via the constant current means Q2 and the parallel circuit of the output capacitor C3 and LED1, the gate can be made a sufficient negative voltage, The switching element Q1 is maintained in the off state.

  When the reduced current flowing through the second circuit B becomes 0, the negative voltage applied to the gate of the wide band gap semiconductor switching element Q1 is not induced, and at the same time, the voltage at which the gate becomes positive due to the counter electromotive force is driven. Since it is induced by the line DW, the wide band gap semiconductor switching element Q1 is turned on again, and thereafter the same circuit operation as described above is repeated. As a result, the DC power source is connected between the output terminals t7 and t8 at both ends of the output capacitor C3. A DC output voltage that is stepped down from the output voltage of 2a appears.

  As is apparent from the above circuit operation, the DC-DC converter 2b performs a step-down chopper operation, and an output current in which an increase current and a decrease current alternately flow is formed in LED1 connected between its output terminals t7 and t8. The LED 1 is lit by these DC components, and the output capacitor C3 bypasses the high frequency component.

  Next, the arrangement of other circuits (not shown) associated with the lighting circuit 2 will be described. Examples of other circuits include a dimming signal receiving circuit (for example, a photocoupler) and a remote control circuit receiving circuit. Apart from that, it is preferably arranged in the insulating case 12, for example, together with the DC power source 2a.

[Second Embodiment]
A second embodiment will be described with reference to FIG. 5A is a plan view of the light diffuser seen through, and FIG. 5B is a side sectional view. The same parts as those in FIG. 1 are denoted by the same reference numerals.

  In the second embodiment, the LED 1 and the DC-DC converter 2b are mounted on the same surface on the LED substrate 11 that also serves as the heat dissipation means 3, and the light emitting surface side of these assemblies is covered with the light diffuser 6, so that the LED The entire lighting device is modularized.

  The specific configuration of the LED substrate 11 that also serves as the heat dissipation means 3 is not particularly limited. For example, for example, a structure formed by printing a wiring pattern on an aluminum nitride (SiAl) substrate or a structure formed by attaching a thin plastic sheet formed by printing a wiring pattern to a metal substrate having high thermal conductivity such as aluminum. A configuration in which a heat conductive metal plate is disposed on the intermediate layer of the substrate is allowed.

  The DC-DC converter 2b allows the same thing as in the first embodiment described above. However, if desired, in addition to the DC-DC converter 2b, the portion of the DC power source 2a can be heat-resistant and mounted together so that almost the entire lighting circuit can be integrally mounted on the LED substrate 11.

  Further, a high-heat-resistant power circuit component of the DC-DC converter 2b, for example, the wide band gap semiconductor switching element Q1, the constant current means Q2, the diode D1, and the inductor L1 shown in FIG. 2a is mounted on an inexpensive separate wiring board 13 made of paper phenol or glass epoxy, which has relatively low heat dissipation, and this wiring board 13 is arranged so as to be perpendicular to the LED board 11. be able to. By so doing, heat transfer from the LED substrate 11 to the DC power source 2a can be suppressed, and therefore, the component circuit components of the DC power source 2a need not be made highly heat resistant.

  Further, the DC-DC converter 2b is disposed in the central portion of the LED substrate 11 that also serves as the heat dissipation means 3. As a result, there is an advantage that dispersion of the heat generating portion with respect to the heat radiating means 3 is improved and the light distribution characteristics are not adversely affected.

  Furthermore, a light reflecting film can be disposed on the outer peripheral surface of the DC-DC converter 2b mounted on the LED substrate 11 together with the LED 1. Thereby, the light distribution characteristic of an LED illuminating device can be improved, or a total luminous flux can be increased.

  The light diffuser 6 is made of a transparent resin, such as polycarbonate, uniformly with one or more kinds of fine particles selected from the group of highly reflective metal compounds, such as titanium oxide, aluminum oxide, silicon oxide, strontium pyrophosphate and calcium pyrophosphate. It can be obtained by dispersing in. Moreover, an LED lighting device can be formed by placing the assembly in a mold and then casting and solidifying the flowable material of the light diffuser 6.

  Thus, the obtained LED lighting device in the present embodiment can be thin and downsized. Therefore, this LED illumination device can be used alone for illumination purposes. Further, the LED lighting device of the present embodiment can be used by being mounted in a lighting fixture body as a light source of the lighting fixture.

  1 ... LED, 2 ... lighting circuit, 2a ... DC power supply, 2b ... DC-DC converter, 3 ... heat dissipation means, 3a, 11a, 12a ... through hole, 3b ... standing edge, 4 ... translucent cover, 4a ... around Step part, 5 ... Power receiving means, 11 ... LED substrate, 12 ... Insulating case

Claims (4)

With LED;
DC-DC that rectifies and smoothes AC voltage and obtains DC voltage and DC-DC that includes wide band gap semiconductor switching elements and receives DC voltage obtained from DC power supply and operates at switching frequency in MHz range to activate LED A lighting circuit with a converter;
A common heat dissipating means for cooling the LED and DC-DC converter by arranging them on the same surface;
LED lighting device characterized by comprising.   The LED lighting device according to claim 1, wherein the lighting circuit has a direct current power source arranged away from the DC-DC converter and connected to the DC-DC converter via a conducting wire.   3. The LED lighting device according to claim 1, wherein the heat dissipating means has an LED attached to the peripheral side thereof and a DC-DC converter attached to the center side of the LED.   3. The LED lighting device according to claim 1, wherein the heat dissipating means has a DC-DC converter attached relatively to the peripheral side thereof and an LED attached to the center side of the DC-DC converter.

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