JP6915317B2 - Lighting device - Google Patents

Description

The present invention relates to, for example, a lighting device used for emitting light of an LED, and a luminaire provided with the lighting device.

Patent Document 1 discloses that an AC voltage from a commercial power source is supplied to a rectifier circuit via a noise filter circuit. The noise filter circuit removes noise generated inside the lighting device and prevents unnecessary noise from flowing out to the commercial power supply side. Patent Document 1 describes a common mode choke coil for removing common mode noise by winding windings connected to each of the input voltage lines around a common core, and input voltage lines before and after the common mode choke coil. It is disclosed that a noise filter circuit is configured by an cross-the-line capacitor connected between them and a normal mode choke coil for removing normal mode noise.

Japanese Unexamined Patent Publication No. 2006-351353

For example, in order to satisfy the CISPR standard and the like, noise reduction of the lighting device is required. In particular, there has been a demand for noise reduction in a low frequency band of, for example, about 9 kHz to 150 kHz. It is preferable to realize noise reduction while avoiding an increase in the size of the lighting device.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a lighting device and a lighting device capable of reducing noise while avoiding an increase in size of the device.

The lighting device according to the present invention includes a filter circuit connected to an AC power supply, a power factor improving circuit connected to the output of the filter circuit, and a lighting circuit connected to the output of the power factor improving circuit. provided, the filter circuit includes a choke coil having a core of closed magnetic circuit form, have a capacitor connected in parallel to the AC power supply, the capacitance of the capacitor is less than 0.47 .mu.F, the filter circuit 9kHz~150kHz It is characterized by reducing noise in the low frequency band of.

Other features of the present invention will be clarified below.

According to the present invention, for example, by providing a choke coil having a closed magnetic circuit core in the filter circuit, noise can be reduced while avoiding an increase in size of the device.

It is a circuit diagram of the lighting equipment which concerns on Embodiment 1. FIG. It is a perspective view of a choke coil. It is a perspective view which shows the modification of the choke coil. It is a perspective view which shows another modification of the choke coil. It is a circuit diagram of the lighting equipment which concerns on the modification. It is a circuit diagram of the lighting equipment which concerns on Embodiment 2. FIG. It is sectional drawing of the LED module which concerns on Embodiment 3. FIG. It is a circuit diagram of the lighting circuit of the lighting equipment which concerns on Embodiment 4. FIG. It is a hardware block diagram of a control circuit.

The lighting device and the luminaire according to the embodiment of the present invention will be described with reference to the drawings. The same or corresponding components may be designated by the same reference numerals and the description may be omitted.

Embodiment 1.
FIG. 1 is a circuit diagram of a lighting fixture according to the first embodiment. This luminaire includes a lighting device 10. The lighting device 10 includes a filter circuit 14 connected to an AC power supply 12. A power factor improving circuit 16 is connected to the output of the filter circuit 14. A lighting circuit 18 is connected to the output of the power factor improving circuit 16. The output of the lighting circuit 18 is connected to the LED module 20.

The filter circuit 14 includes a capacitor C1 connected in parallel to the AC power supply 12. A common mode choke coil L1 is connected in parallel to the capacitor C1. A choke coil L2 and a capacitor C2 are connected in series to the common mode choke coil L1. The midpoint between the choke coil L2 and the capacitor C2 and the midpoint between the capacitor C2 and the common mode choke coil L1 are the outputs of the filter circuit 14. The capacitance of the capacitors C1 and C2 is, for example, 0.1 μF. If the AC power supply 12 does not need to be transformed, the common mode choke coil L1 may be omitted.

FIG. 2 is a perspective view of the choke coil L2. The choke coil L2 is formed by winding the lead wire W1 around an EE-shaped core EEC instead of a drum-shaped core. The core EEC is made of a magnetic material such as ferrite. One end T1 of the conductor W1 is connected to the common mode choke coil L1, and the other end T2 is connected to the capacitor C2. The choke coil L2 is provided to remove noise from the power supply.

Here, a comparative example will be considered. The lighting fixture of the comparative example is different from the filter circuit 14 according to the first embodiment in that the choke coil L2 is a drum-shaped choke coil having an open magnetic circuit structure. The drum type choke coil is an inexpensive choke coil that is widely used. The inductance of the choke coil L2 of the comparative example is several hundred μH. Specifically, for example, it is about 330 μH. If the output power is up to about 50 W, the capacitance of the capacitor C3 of the power factor improving circuit 16 is up to about 0.47 μF. With such a filter constant, it is difficult to attenuate noise in the low frequency band of 9 kHz to 150 kHz.

In order to reduce noise in the low frequency band of 9 kHz to 150 kHz, it is desired to increase the capacitances of the capacitors C1 and C2, but doing so reduces the power factor of the input current. Further, if the capacities of the capacitors C1 and C2 are increased, the size of the capacitor is increased. Therefore, there is a limit to increasing the capacitance of the capacitors C1 and C2. Therefore, we would like to deal with this by increasing the choke coil L2 formed by the drum-type choke coil, but if the inductance value of the drum-type choke coil is increased, the current that can flow becomes smaller. That is, the rated current cannot be maintained.

On the other hand, by using the choke coil L2 according to the first embodiment of the present invention shown in FIG. 2, the rated current and the inductance value of the choke coil L2 can be increased. For example, the inductance value can be increased to about several mH. The inductance of the choke coil L2 is preferably 1 mH or more. Moreover, there is no increase in the size of the lighting equipment by adopting the EE type core EEC. As a result, the filter circuit 14 can reduce noise in a low frequency band of about 9 kHz to 150 kHz.

FIG. 3 is a perspective view showing a modified example of the choke coil L2. The choke coil L2 has an EI type core EIC made of a magnetic material. The conductor W2 is wound around the core EIC.

FIG. 4 is a perspective view showing another modification of the choke coil L2. The choke coil L2 has an ER-shaped core ERC formed of a magnetic material. The conductor W3 is wound around the core ERC.

Returning to the description of FIG. A power factor improving circuit 16 is connected to the output of the filter circuit 14.
The electric power input to the power factor improving circuit 16 is rectified by the rectifier 16A. The power factor improving circuit 16 includes a step-up chopper circuit that charges the rectified pulsating current voltage to a predetermined DC high voltage in the capacitor C4. The boost chopper circuit includes a coil L3 whose one end is connected to the high potential side of the rectifier 16A, a switching element SW1 whose drain side is connected to the other end of the coil L3, and a connection between the other end of the coil L3 and the drain side of the switching element SW1. It is composed of a diode D1 in which an anode is connected to a point.

When the switching element SW1 is OFF, a current flows through the diode D1, and at this time, when the switching element SW1 is ON, the energy stored in the coil L3 is further released to charge the capacitor C4. The positive electrode of the capacitor C4 is connected to the cathode of the diode D1, and the negative electrode is connected to the low potential side of the rectifier 16A. The charging voltage of the capacitor C4 is divided by the resistance elements R1 and R2 connected in series, and is input to the control circuit 16B via the FB unit 16C. The control circuit 16B outputs a switching signal for controlling the switching element SW1 so that the voltage dividing voltage becomes constant. The switching element SW1 is on / off controlled by the switching signal. In this way, the boost chopper circuit is controlled so that the output voltage becomes a constant voltage.

The control circuit 16B is, for example, a microcomputer. Since the operating voltage of the microcomputer is insufficient for driving the switching element SW1, the operating voltage of the microcomputer cannot be applied to the switching element SW1 as it is. Therefore, it is preferable that the switching signal is once input from the control circuit 16B to the MOSFET driver, the signal level is raised by the MOSFET driver, and then the signal is supplied to the switching element SW1 to perform stable switching.

The lighting circuit 18 constitutes, for example, a back converter circuit. A well-known back converter circuit can be a lighting circuit 18. The output current of the lighting circuit 18 lights the LED module 20.

As described above, in the lighting device 10 according to the first embodiment of the present invention, the inductance value of the choke coil L2 can be increased by using the choke coil L2 having a closed magnetic circuit structure. Therefore, a low noise LED power supply can be supplied.

The lighting device and the luminaire according to the first embodiment of the present invention can be variously modified without losing their characteristics. For example, the choke coil L2 may have a closed magnetic path type core, and may have a shape other than the EE type, the EI type, and the ER type.

FIG. 5 is a circuit diagram of a lighting fixture according to a modified example. The luminaire of FIG. 5 is the luminaire of FIG. 1 from which the capacitor C2 has been removed. Therefore, the filter circuit 14 includes only one capacitor connected in parallel to the AC power supply 12. The only capacitor provided in the filter circuit 14 is the capacitor C1. Even when the capacitor C2 is deleted in this way, it is possible to reduce noise in a low frequency band of about 9 kHz to 150 kHz by providing the choke coil L2.

These modifications can be applied to the lighting device and the luminaire according to the following embodiments. Since the lighting device and the lighting fixture according to the following embodiment have much in common with the first embodiment, the differences between the lighting device and the lighting fixture according to the first embodiment will be mainly described.

Embodiment 2.
FIG. 6 is a circuit diagram of the lighting equipment according to the second embodiment. The filter circuit 30 connected to the AC power supply 12 includes a line filter LF. The line filter LF is provided to filter the noise from the AC power supply 12 and to prevent the noise of the lighting device 10 from being emitted to the outside. As the line filter LF, for example, a well-known power supply line filter composed of a coil and a capacitor can be used.

Further, as the line filter LF, a hybrid line filter having both the inductance value of the common mode component and the inductance value of the normal mode component can be used. This makes it possible to reduce the number of parts. That is, the common mode choke coil and the normal mode choke coil can be combined into one component.

Embodiment 3.
FIG. 7 is a cross-sectional view of the LED module 20 according to the third embodiment. The LED module 20 receives a current supply from the lighting circuit 18. The LED module 20 includes a grounding metal housing 20A, a printed circuit board 20B provided on the grounding metal housing 20A, and an LED package 20C provided on the printed circuit board 20B. The printed circuit board 20B has a wiring pattern 20D on the upper surface. The wiring pattern 20D is, for example, a copper foil pattern. The LED package 20C is connected to this wiring pattern 20D. The LED emits light when a current is supplied from the wiring pattern 20D to the LED in the LED package 20C.

The grounding metal housing 20A is connected to the ground. Then, a stray capacitance 20b is generated between the wiring pattern 20D and the grounded metal housing 20A for grounding. The stray capacitance 20b is a parasitic capacitance generated by a parasitic capacitor. Noise flows into the ground through this stray capacitance 20b. As a result, it is possible to mainly reduce noise in a high frequency band of 30 MHz or more.

Embodiment 4.
FIG. 8 is a circuit diagram of a lighting circuit 18 of the lighting fixture according to the fourth embodiment. The lighting circuit 18 has a back converter circuit connected to the output of the power factor improving circuit. The back converter circuit includes a switching element SW2, a diode D2, a coil L4, a capacitor C5, and a resistance element R3. A series circuit including the switching element SW2 and the diode D2 is connected in parallel with the capacitor C1 of the step-up chopper circuit. The drain of the switching element SW2 is connected to the positive electrode of the capacitor C4, and the source is connected to the cathode of the diode D2. The coil L4, the capacitor C5 and the resistance element R3 are connected in this order to form a series circuit, and this series circuit is connected in parallel to the diode D2. The DC high voltage charged in the capacitor C4 is smoothed by the capacitor C5 via the back converter circuit including the switching element SW2, the coil L4 and the diode D2, supplied to the LED module 20, and the LED is turned on.

The on / off of the switching element SW2 is controlled by the control circuit 18A. The control circuit 18A changes the switching frequency of the switching element SW2 with time between a first frequency higher than the predetermined frequency and a second frequency smaller than the predetermined frequency. "Predetermined frequency" is, for example, 50 k Hz, the first frequency is 51 k Hz for example, the second frequency is 49 k Hz, for example. In this case, 50 k Hz operation, 51 k Hz operation, 50 k Hz operation, 49 k Hz operation, 50 k Hz operation is performed in this order.

When the switching frequency of the switching element SW2 is constant, noise may increase due to the specifications of the measuring instrument. Therefore, in the fourth embodiment, the switching frequency of the back converter circuit is changed with time. Since the amount of change in frequency was small as +1 k Hz or -1 k Hz, it does not affect the actual operation. That is, it is substantially the same as operating at 50 kHz. Variation of the switching frequency is preferably about ± 1 k Hz, possible to increase the change amount is not preferable. It is not possible to traverse the switching frequency, for example, between 30-80 k Hz. If the amount of change in the switching frequency is large in this way, feedback control may not be possible in consideration of the response speed.

The control circuit 18A is a CPU (also referred to as a Central Processing Unit, a central processing unit, a processing device, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP) that executes a program stored in a memory even if it is dedicated hardware. It may be. When the processing circuit is dedicated hardware, the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

FIG. 9 shows a configuration example of the control circuit 18A when the processing circuit is a CPU. In this case, each function of the control circuit 18A is realized by software or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 18c. The processor 18b realizes each function by reading and executing the program stored in the memory 18c. That is, it includes a memory 18c for storing a program that changes the switching frequency of the switching element SW2 with time. The receiving device 18a receives a signal from the FB unit 18B, and the processor 18b and the memory 18c operate according to the signal received by the receiving device 18a to determine the switching frequency. The determined switching frequency is transmitted from the transmission device 18d to the switching element SW2. Here, the memory 18c corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, an EEPROM, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD, or the like. Of course, some of the above functions may be realized by hardware, and some may be realized by software or firmware. The features of the lighting device and the lighting fixture according to each embodiment described so far may be used in combination.

12 AC power supply, 14 filter circuit, 16 power factor improvement circuit, 18 lighting circuit, 20 LED module, L2 choke coil

Claims (4)

The filter circuit connected to the AC power supply and
A power factor improving circuit connected to the output of the filter circuit and
A lighting circuit connected to the output of the power factor improving circuit is provided.
It said filter circuit is closed and the choke coil having a core of closed magnetic circuit form, a capacitor connected in parallel to the alternating current power supply,
The capacitance of the capacitor is 0.47 μF or less.
The filter circuit is a lighting device characterized by reducing noise in a low frequency band of 9 kHz to 150 kHz. The lighting device according to claim 1, wherein the core is an EE-type, EI-type, or ER-type core made of a magnetic material. The filter circuit includes one capacitor connected in parallel to the AC power supply.
The lighting device according to claim 1 or 2, wherein the capacitor provided in the filter circuit is only the capacitor. The lighting device according to any one of claims 1 to 3, wherein the choke coil has an inductance of 1 mH or more.

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