JP2006147368A - Discharge lamp lighting device and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device of an HID lamp which suppresses a noise level in a tolerance limit by improving frequency pair noise characteristics and to provide a lighting system. <P>SOLUTION: In the discharge lamp lighting device including a rectifying circuit 3 for rectifying an ac power supply, an active filter circuit 4, a series circuit of first and second smoothing capacitors C6 and C7, a series circuit of first and second switching elements Q2 and Q3, a series circuit of a discharge lamp 6 and an inductor L3 connected between the connecting point of the series circuit of the first and second switching elements Q2 and Q3 and the connecting point of the series circuit of the first and second smoothing capacitors C6 and C7, first and second diodes D6 and D7 connected at opposite direction in parallel with the first and second switching elements, and a metal housing which holds the above circuits and circuit elements; the connecting point of the first and second smoothing capacitors C6 and C7 is connected to the metal housing through capacitors C10 and C11 for removing a noise. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device for lighting a high-intensity discharge lamp (hereinafter referred to as an HID lamp) and a reduction in noise level of the lighting device.

  Conventionally, a noise filter circuit is generally inserted in the power supply input unit for the purpose of noise reduction. Furthermore, the power input unit employs a method of connecting the power input unit to a grounded metal casing via a capacitor.

  FIG. 7 shows a conventional discharge lamp lighting device. A noise filter circuit 2 including a capacitor C1, a choke coil L1, a capacitor C2, and the like is connected to the commercial AC power source 1, and a rectifier circuit 3 composed of a full-wave rectifier diode bridge is connected to the noise filter circuit 2. The negative output terminal of the rectifier circuit 3 is connected to the ground via a ground capacitor C.

  Between the rectification output terminals of the rectifier circuit 3, a capacitor C5 as a high-frequency component passing filter associated with high-frequency switching of the FET Q1 as a switching element is connected, and in the subsequent stage, the output voltage of the rectifier circuit 3 is boosted and A step-up chopper circuit 4 for outputting as a stable DC voltage and improving the input power factor is connected.

  The step-up chopper circuit 4 is composed of a series circuit of a coil L2 as an inductor, a FET Q1, which is a high-frequency switching element, a commutation diode D5, and smoothing capacitors C6, C7.

  In the step-up chopper circuit 4, the control circuit 8 controls the ON period of the high-frequency switching FET Q1 according to the output voltages of the smoothing capacitors C6 and C7, thereby performing feedback control so that the output voltage becomes a constant value. The control is performed by controlling the on-period of the FET Q1 according to the amplitude level of the full-wave rectified voltage based on the monitoring of the full-wave rectified voltage of the rectifier circuit 3 and the current flowing through the coil L2, thereby inputting the input AC current. It is made to correspond to the phase of AC voltage. In other words, the boost chopper circuit 4 functions as an active filter circuit having a function of outputting a stabilized DC voltage and an input power factor improving function.

  An inverter circuit 5 is connected to the subsequent stage of the boost chopper circuit 4. The inverter circuit 5 includes two series of FETs Q2 and Q3 that are connected in parallel to both ends of a series circuit of smoothing capacitors C6 and C7 at the output stage of the boost chopper circuit 4, and parallel to each of the FETs Q2 and Q3. Connected to both ends of the primary windings of the diodes D6 and D7, the coil L3 as an inductor, the step-up transformer T1, the HID lamp 6, and the step-up transformer T1 connected in the opposite direction to the current direction of the FETs Q2 and Q3. The high voltage pulse generating igniter 7 and a capacitor C8 connected in parallel with the HID lamp 6 for bypassing the high-frequency component due to the high-frequency switching of the FETs Q2 and Q3 from the lamp current are provided.

  The series circuit of resistors R1 and R2 connected to both ends of the rectifier circuit 3 is for supplying a divided voltage obtained at the connection point to the control circuit 8 as a starting power supply voltage, and to the coil L2. The rectifier circuit including the diode D8 and the capacitor C9 connected to the provided secondary winding L5 is for supplying a DC voltage obtained at the output terminals A and A 'to the control circuits 8 and 9 as a power supply voltage.

  In the above configuration, a metal casing (not shown) is connected to a series circuit of two capacitors C3 and C4 at both ends on the output end side of the noise filter circuit 2, and the series connection point of C3 and C4 is grounded. ), High-frequency switching noise from the step-up chopper circuit 4 and the inverter circuit 5 is released to the ground side, and high-frequency noise is prevented from leaking to the commercial AC power supply 1.

  Further, as such a prior example, the present applicant has disclosed a power supply device and a discharge lamp which prevent leakage of switching noise to the AC power supply side by including a high-frequency diode for high-speed switching in the rectifier. A lighting device and a lighting device have been proposed (see, for example, Patent Document 1).

In Patent Document 1, by arranging a grounding capacitor on the low frequency AC power supply side with respect to the rectifier, the high-frequency diode in the rectifier also performs a high-frequency switching operation along with the high-frequency switching operation of the switching device in the inverter circuit. Even if switching noise is generated, the high-frequency switching noise caused by the high-frequency diode is prevented from leaking to the low-frequency AC power supply side by flowing it to the ground via a grounding capacitor before reaching the low-frequency AC power supply. Yes.
JP-A-9-28979

  However, as the lamp power increases and the lamp waveform contains more harmonics (for example, square wave lighting), the noise to the input AC power supply tends to increase. May not be possible.

  FIG. 8 shows the result of interference power measurement (noise level measurement at a frequency of 30 MHz to 300 MHz) in the discharge lamp lighting device of FIG. This measuring method is based on the international standard CISPR14. The interference power level at this time exceeds the allowable limit of 55 dBpW in the frequency range of 30 to 80 MHz.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention has an object to provide a discharge lamp lighting device and an illumination device for an HID lamp that can improve frequency-to-noise characteristics and keep the noise level within an allowable limit. It is.

  A discharge lamp lighting device according to a first aspect of the present invention includes: a rectifying circuit that rectifies an output of an AC power supply; an active filter circuit that inputs the rectified output of the rectifying circuit and improves the power factor of the output of the AC power supply; A series circuit of first and second smoothing capacitors connected in parallel to the output side in the active filter circuit; a series circuit of first and second switching elements connected in parallel to the output of the active filter circuit; A series circuit of a discharge lamp and an inductor connected between a connection point of the series circuit of the first and second switching elements and a connection point of the series circuit of the first and second smoothing capacitors; , First and second diodes connected in parallel to the respective switching elements of the series circuit of the second switching elements in a direction opposite to the direction in which the current of each switching element flows. ; Are provided with; and the first, third capacitor connected to the connection point of the series circuit of the second smoothing capacitor between the metal housing.

  In the present invention, for example, a field effect transistor (FET) can be used as the switching element. In this case, a parasitic diode built in the field effect transistor due to its configuration is used for reverse current flow. Alternatively, a switching element that does not incorporate a parasitic diode between the collector and emitter, such as a bipolar transistor, may be mainly used. In this case, the diode is connected in parallel between the collector and emitter with the conduction direction reversed. Connect to Further, the frequency at which the switching element is turned on / off is higher than the frequency of the low-frequency AC power supply, and is preferably several kHz or more, and more preferably 20 kHz or more. The rectified output of the rectifier circuit means a substantially unsmoothed pulsating voltage, and includes such a voltage that the valley of the pulsating voltage is slightly raised. Further, the configuration of the inverter circuit may be a modified half-bridge configuration other than a half-bridge configuration. Further, the discharge lamp may be an arc discharge lamp including a xenon lamp or a fluorescent lamp in addition to an HID lamp such as a mercury lamp, a metal halide lamp, or a high pressure sodium lamp. The above matters also apply to the following inventions.

  According to the discharge lamp lighting device of the present invention, even if high-frequency switching noise occurs due to the high-frequency switching operation of the first and second switching elements in the inverter circuit, the first and second stages before the inverter circuit. By connecting the connection point of the smoothing capacitor to the ground via a capacitor, it is possible to suppress high-frequency switching noise from leaking to the AC power supply side, and to effectively prevent noise.

  A discharge lamp lighting device according to a second aspect of the present invention is the discharge lamp lighting device according to the first aspect, wherein the first and second switching elements alternately perform high-frequency on / off operations of the respective switching elements at a constant period of low frequency. Repeatedly, low frequency AC power is supplied to the discharge lamp.

  According to the discharge lamp lighting device of the present invention, the higher the power of the discharge lamp is, and the more the lighting method includes a higher harmonic in the discharge lamp waveform (for example, lighting with a rectangular wave with a constant frequency at a low frequency). Although noise tends to increase, it is effective for noise reduction in a discharge lamp lighting device employing such a lighting system.

  A discharge lamp lighting device according to a third aspect of the present invention is the discharge lamp lighting device according to the first or second aspect, further comprising a noise filter circuit including a common mode choke inserted between the AC power supply and the rectifier circuit. It is characterized by that.

  According to the discharge lamp lighting device of the present invention, in addition to the noise reduction by the grounding capacitor connected between the connection point of the series circuit of the first and second smoothing capacitors and the metal casing, between the AC power source and the rectifier circuit. The noise that leaks to the AC power supply side can be further reduced by the inserted noise filter circuit.

  A discharge lamp lighting device according to a fourth aspect of the present invention is the discharge lamp lighting device according to any one of the first to third aspects, wherein the third capacitor is 300 pF or more.

  According to the discharge lamp lighting device of the present invention, a high-frequency switching noise having a capacitance value of 300 pF or more is effective as a noise removing capacitor.

  A discharge lamp lighting device according to a fifth aspect of the present invention is the discharge lamp lighting device according to any one of the first to fourth aspects, wherein the discharge lamp is an HID lamp.

  According to the discharge lamp lighting device of the present invention, the more the harmonics are included in the lamp waveform (for example, rectangular wave lighting), the more effective the noise reduction associated with the lighting of the HID lamp that the noise to the input AC power source is likely to increase.

  A discharge lamp lighting device according to a sixth aspect of the invention is characterized in that, in the discharge lamp lighting device according to any one of the first to fifth aspects, a circuit and circuit components are housed in a grounded metal casing. .

  According to the discharge lamp lighting device of the present invention, the circuit and the circuit components used in the discharge lamp lighting device according to any one of claims 1 to 5 are accommodated in a metal casing, so that these circuits and circuits are provided. Noise emitted from the parts to the outside can be prevented.

  An illuminating device according to a seventh aspect of the present invention comprises: the discharge lamp lighting device according to any one of the first to sixth aspects; an HID lamp as a discharge lamp; and an instrument for holding the HID lamp. Yes.

  According to the lighting device of the present invention, even if high-frequency switching noise is generated in association with the high-frequency switching operation of the first and second switching elements in the inverter circuit in the discharge lamp lighting device, the first stage before the inverter circuit is generated. By connecting the connection point of the second smoothing capacitor to the ground through the grounding capacitor, it is possible to prevent high-frequency switching noise from leaking to the AC power supply side, and to prevent noise.

  According to the present invention, noise can be reduced without using special components.

  Embodiments of the invention will be described with reference to the drawings.

  1 is a circuit diagram showing a discharge lamp lighting device according to a first embodiment of the present invention. The same components as those in the conventional example of FIG.

  In FIG. 1, a capacitor C1, a choke coil L1 for reducing common mode noise, and a capacitor C2 are connected between two AC power supply lines connected to both ends of a commercial AC power supply 1 which is a low frequency (for example, 50 Hz) power supply. A connected noise filter circuit 2 is connected, and a rectifier circuit 3 composed of a full-wave rectifier diode bridge is connected to the noise filter circuit 2. The negative output terminal of the rectifier circuit 3 is connected to the ground via a ground capacitor C.

  Between the full-wave rectification output terminals of the rectifier circuit 3, a capacitor C5 is connected as a high-frequency component passing filter associated with high-frequency switching of a high-frequency switching FET Q1, which will be described later, and the output voltage of the rectifier circuit 3 is connected to the subsequent stage. A step-up chopper circuit 4 for boosting and outputting as a stable DC voltage and improving the input power factor is connected.

  The step-up chopper circuit 4 is an active filter circuit that inputs a full-wave rectified output from the rectifier circuit 3 and generates a stabilized DC voltage with a constant amplitude at a high power factor under the control of the control circuit 8. An active filter circuit having only a part of the function of the step-up chopper circuit 4, that is, an input power factor improvement function for matching the phase of the input AC current and the input AC power supply voltage is connected between the rectification output terminals of the rectifier circuit 3. May be.

  The step-up chopper circuit 4 includes a coil L2 having one end connected to one output end (+ voltage output end in the figure) of the rectifier circuit 3, the other end of the coil L2, and the other output end of the rectifier circuit 3. FET Q1 as a high-frequency switching element whose drain and source are connected between (the voltage output terminal in the figure), a commutation diode D5 whose anode is connected to the connection point between the coil L2 and FET Q1, and this commutation diode And a series circuit of first and second smoothing capacitors C6 and C7 connected between the cathode of D5 and the negative voltage output terminal of the rectifier circuit 3.

  The control circuit 8 controls the ON period of the high-frequency switching FET Q1 according to the output voltage of the series circuit of the first and second smoothing capacitors C6 and C7 of the step-up chopper circuit 4, so that the output voltage becomes a constant value. The feedback control is performed so that the amplitude level of the full-wave rectified voltage of the rectifier circuit 3 is monitored (voltage detection at the + voltage output terminal of the rectifier circuit 3) and the current level flowing through the coil L2 (coil L2 is controlled). The input power factor is improved to match the input AC current to the phase of the input AC voltage by controlling the ON period of the FET Q1 in accordance with the amplitude level of the full-wave rectified voltage based on the current detection by the secondary winding L4. We are also controlling. Thus, the boost chopper circuit 4 has a function of outputting a stabilized DC voltage and an input power factor improving function. Note that the switching frequency of the FET Q1 is several tens of kHz.

An inverter circuit 5 is connected to the subsequent stage of the boost chopper circuit 4.
The inverter circuit 5 is connected in parallel to both ends of the series circuit of the smoothing capacitors C6 and C7 of the step-up chopper circuit 4 so as to perform a high-frequency (for example, several tens of kHz) switching operation of FETQ2, Connection point of the series circuit of Q3, the diodes D6 and D7 connected in parallel to the direction of the current of the FETs Q2 and Q3 in parallel with the first and second FETs Q2 and Q3, respectively, and the series circuit of the FETs Q2 and Q3 And a coil L3 as an inductor, a starting step-up transformer T1 (secondary winding thereof), and an HID lamp 6 connected between the first and second smoothing capacitors C6 and C7. For a series circuit, an igniter 7 connected to both ends of the primary winding of the step-up transformer T1 to generate a high-voltage pulse for starting, and a series circuit of the HID lamp 6 and the step-up transformer T1 Are columns connected, the current flowing through the HID lamp 6, and a capacitor C8 for causing the bypass (bypass) a high frequency component by the high frequency switching of the FET Q2, Q3, and. When an FET is used as the switching element, a parasitic diode built in the FET is used for the reverse current conducting diodes D6 and D7, so that no special diode connection is required.

  A series circuit of resistors R1 and R2 connected to both ends of the rectifier circuit 3 is for supplying a divided voltage obtained at the connection point to the control circuit 8 as a starting power supply voltage, and is provided in the coil L2. The rectifier circuit including the diode D8 and the capacitor C9 connected to the secondary winding L5 is for supplying the rectified DC voltage at the rectified output terminals A and A ′ to the control circuits 8 and 9 as a power supply voltage.

  Further, in the first embodiment of the present invention, the connection point of the series circuit of the first and second smoothing capacitors C6 and C7 of the step-up chopper circuit 4 is connected to a metal housing (not shown) via the series circuit of two capacitors C10 and C11. Alternatively, the inverter circuit 5 and the step-up chopper circuit are connected by connecting the C3 and C4 series connection points to a grounded metal casing (not shown). The high frequency switching noise from 4 is released to the ground side.

  In the above configuration, the circuit circuit, at least the rectifier circuit 3, the step-up chopper circuit 4, the inverter circuit 5, the igniter 7, the control circuits 8 and 9, and the high-frequency switching noise removing capacitors C10 and C11 have a series circuit. Contained in the body. The combined capacitance when the capacitors C10 and C11 are connected in series is set to 1500 pF, for example.

  In the above configuration, the connection point of the series circuit of the first and second smoothing capacitors C6 and C7 is connected to the metal casing or the metal casing connected to the ground via the series circuit of the two capacitors C10 and C11. Therefore, the high frequency switching noise from the inverter circuit 5 and the step-up chopper circuit 4 is released to the ground side by connecting the series connection point of C3 and C4 to a metal casing (not shown) connected to the ground. Inflow of high frequency noise to the commercial AC power source 1 can be prevented.

Next, the operation of the discharge lamp lighting device configured as described above will be described with reference to FIGS.
When the AC power supply is turned on in the discharge lamp lighting device of FIG. 1, the voltage obtained by dividing the rectified voltage from the connection point of the voltage dividing resistors R1 and R2 connected to both ends of the full-wave rectified output end of the rectifier circuit 3 is the control circuit. 8, the on / off switching operation by the high frequency of the FET Q1 of the step-up chopper circuit 4 is started.

  In the step-up chopper circuit 4, energy is stored in the coil L2 when the FET Q1 is turned on, the diode D5 is conducted when the FET Q1 is turned off, and the energy stored in the coil L2 is converted into the first and second output capacitors. It discharges toward the series circuit of smoothing capacitors C6 and C7. At this time, since the voltage generated in the coil L2 is added in series to the input voltage, the output voltage is higher than the input voltage. When used as a high power factor chopper circuit, it is preferable to use in a current mode in which the energy stored in the coil L2 is completely discharged (that is, the current flowing through the coil L2 becomes zero). When the control circuit 8 detects the current value via the secondary winding L4 of the coil L2, it can be detected that the current flowing through the coil L2 has become 0. At this time, the control circuit 8 turns on the FET Q1. By doing so, the waveform of FIG. 2A is obtained.

  FIG. 2A shows a current waveform flowing through the coil L2, and FIG. 2B shows a current waveform flowing through the FET Q1. Each of these waveforms is a waveform that periodically coincides with the cycle of high-frequency switching.

  The control circuit 8 supplies a switching pulse to the gate of the FET Q1, which is a switching element. The ON period of the switching pulse is controlled in accordance with the output voltage of the smoothing capacitors C6, C7, which is the output voltage of the boost chopper circuit 4. As a result, the on-time of the FET Q1 is PWM-controlled to control the output voltage from the output capacitors C6 and C7.

  The control of the on-time of the FET Q1 is also performed by the control circuit 8 detecting the amplitude level of the + full-wave rectified voltage of the rectifying circuit 3 and changing the on-time of the FET Q1 in accordance with the amplitude level. By controlling the FET Q1 to have a shorter on-time as the amplitude level of the rectified voltage is smaller and to increase the on-time of the FET Q1 as the amplitude level of the rectified voltage is larger, the waveform of the input AC current is shown by a one-dot chain line in FIG. As shown in Fig. 5, it is shaped into a sine wave having a low frequency (for example, 50 Hz) and changes in synchronization with the waveform of the input AC voltage. That is, the power factor is improved.

  When the step-up chopper circuit 4 starts operation as described above, the AC voltage induced in the secondary winding L5 of the coil L2 is rectified by the rectifier circuit of the diode D8 and the capacitor C9, and the rectified voltage is supplied to the control circuit 9. By being supplied, power is supplied from the control circuit 9 to the igniter 7, and at the same time, switching pulses are supplied to the FETs Q2 and Q3 which are the first and second switching elements. As a result, the igniter 7 generates a high-pressure pulse to place the HID lamp 6 in a discharged state (lighted state), and a high-frequency on / off switching pulse is applied to the FETs Q2 and Q3.

  FIG. 4 (a) shows the high frequency on / off operation of the FET Q2, and FIG. 4 (b) shows the high frequency on / off operation of the FET Q3. FIG. 4C shows a low-frequency lamp current flowing through the HID lamp 6.

  At this time, the control circuit 9 controls the FETs Q2 and Q3 to alternately repeat the ON / OFF operation of the respective high-frequency switching (for example, 50 kHz) at a constant frequency T of the low-frequency (for example, 100 Hz). Low-frequency AC power is supplied.

  The operation of the inverter circuit 5 will be described. First, the operation of turning on / off the FET Q2 during the period T will be described. When an ON pulse is applied to the gate of the FET Q2 and the FET Q2 is turned on, the current flows from C6 → Q2 → coil L3 → T1 → HID lamp 6 → C6 using the charging voltage of the smoothing capacitor C6 as a power source. Due to the energy stored in the coil L3, the current flows through the coil L3-> T1-> HID lamp 6-> C7-> diode D7-> L3. A current flows in the direction of L3 → HID lamp 6.

  In the next period T, the FET Q3 is turned on / off. When an on-pulse is applied to the gate of FET Q3 and FET Q3 is turned on, a current flows from C7 → HID lamp 6 → T1 → coil L3 → Q3 → C7 using the charging voltage of the smoothing capacitor C7 as a power source. Due to the current stored in the coil L3 → diode D6 → C6 → HID lamp 6 → T1 → L3 due to the energy stored in the L3, the HID lamp 6 is always in the next period T during which the FET Q3 is performing high-frequency switching operation. A current flows in the direction of the HID lamp 6 → the coil L3. Accordingly, a low-frequency lamp current as shown in FIG. 4C flows through the HID lamp 6 while being driven at a high frequency.

  The high-frequency component is superimposed on the low-frequency lamp current shown in FIG. 4 (c) by the high-frequency switching operation of the FETs Q2 and Q3. This high-frequency component is bypassed by the capacitor C8. A high-frequency component is not included in the lamp current flowing through the lamp, for example, it is lit with a low-frequency rectangular wave (indicated by a solid line) of 100 Hz (= period 2T).

  FIG. 5 shows the result of interference power measurement (noise level measurement at a frequency of 30 MHz to 300 MHz) in the discharge lamp lighting device of FIG. This measuring method is based on the international standard CISPR14. It can be said that in the frequency range of 30 to 80 MHz, the allowable limit of 55 dBpW is not exceeded, and the noise level can be reduced.

  The reason that the noise level can be reduced in this way is that the inverter circuit 5 uses the charging voltages of the first and second smoothing capacitors C6 and C7 in the output stage of the boost chopper circuit 4 in the previous stage as the power supply voltage. Since it operates, by connecting it to the metal housing via the capacitors C10 and C11 at the connection point of the series circuit of the first and second smoothing capacitors C6 and C7, the high frequency noise component on the power supply voltage is removed. The noise can be reduced by escaping to the metal casing or the ground side through the capacitor for use.

FIG. 6 is a cross-sectional view showing an embodiment of the illumination device of the present invention using the discharge lamp lighting device of FIG.
In FIG. 6, the code | symbol 11 is a lighting fixture main body, 12 is a reflector. The HID lamp 6 that is a discharge lamp is mounted and held at an appropriate position (for example, the center) of the reflector 12 of the luminaire body 11. Further, a discharge lamp lighting device 10 having the configuration described with reference to FIG. In this case, the noise removing capacitors C10 and C11 are grounded through the lighting fixture body 11.

  In the above description of the first embodiment, the noise removing capacitors C10 and C11 are two capacitors connected in series in order to adjust the capacitance value to an appropriate value. However, in the present invention, at least one capacitor is used. What is necessary is just to comprise with a capacitor | condenser.

  The present invention can be applied to noise reduction in general lighting devices for arc discharge lamps including HID lamps such as mercury lamps, metal halide lamps, and high-pressure sodium lamps, as well as xenon lamps and fluorescent lamps.

The circuit diagram which shows the discharge lamp lighting device of Example 1 of this invention. The timing chart which shows the current waveform which flows into the coil in a step-up chopper circuit, and the current waveform which flows into a switching element. The wave form diagram which shows the high frequency current waveform which flows into the switching element in a step-up chopper circuit. The timing chart which shows the 1st, 2nd high frequency switching operation | movement in an inverter circuit, and a lamp current waveform. The characteristic figure of the frequency versus disturbance power which shows the disturbance power measurement result in the discharge lamp lighting device of FIG. Sectional drawing which shows the Example of the illuminating device of this invention using the said discharge lamp lighting device of FIG. The circuit diagram which shows the discharge lamp lighting device of a prior art example. FIG. 8 is a characteristic diagram of frequency versus jamming power showing the jamming power measurement result in the discharge lamp lighting device of FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... AC power supply 2 ... Noise filter circuit 3 ... Rectifier circuit 4 ... Boost chopper circuit (active filter circuit)
5 ... Inverter circuit 6 ... HID lamp (discharge lamp)
DESCRIPTION OF SYMBOLS 10 ... Discharge lamp lighting device C6, C7 ... 1st, 2nd smoothing capacitor Q1 ... FET (switching element)
Q2, Q3 ... FET (first and second switching elements)
C10, C11 ... Noise removing capacitors L3 ... Coils (inductors)
Agent Patent Attorney Susumu Ito

Claims (7)

A rectifier circuit for rectifying the output of the AC power supply;
An active filter circuit that inputs the rectified output of the rectifier circuit and improves the power factor of the output of the AC power supply;
A series circuit of first and second smoothing capacitors connected in parallel to the output side in the active filter circuit;
A series circuit of first and second switching elements connected in parallel to the output of the active filter circuit;
A discharge lamp and inductor series circuit connected between a connection point of a series circuit of the first and second switching elements and a connection point of a series circuit of the first and second smoothing capacitors;
First and second diodes connected in parallel to the respective switching elements of the series circuit of the first and second switching elements in a direction opposite to the direction of current flow of each switching element;
A third capacitor connected between the connection point of the series circuit of the first and second smoothing capacitors and the ground;
A discharge lamp lighting device comprising:   The first and second switching elements alternately repeat high-frequency on / off operations of the respective switching elements at a constant period of low frequency, and low-frequency AC power is supplied to the discharge lamp. Item 2. A discharge lamp lighting device according to Item 1.   The discharge lamp lighting device according to claim 1, further comprising a noise filter circuit including a common mode choke inserted between the AC power supply and the rectifier circuit.   The discharge lamp lighting device according to any one of claims 1 to 3, wherein the third capacitor is 300 pF or more.   The discharge lamp lighting device according to any one of claims 1 to 4, wherein the discharge lamp is an HID lamp.   6. The discharge lamp lighting device according to claim 1, wherein a circuit and circuit components are housed in a metal casing that is grounded. A discharge lamp lighting device according to any one of claims 1 to 6;
An HID lamp as a discharge lamp;
An instrument body holding the HID lamp;
An illumination device comprising:

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