JP2005050701A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and cheap discharge lamp lighting device. <P>SOLUTION: The discharge lamp lighting device has an FET 30 turning voltage on and off supplied to both ends of a primary winding 21 of a transformer 20 with a prescribed cycle, and an HID bulb 50 connected to both ends of a secondary winding 22 of the transformer 20. A ratio of the number of turns of the primary winding 21 to that of the secondary winding of the transformer 20 is decided to be such value that generates a voltage induced at the secondary winding 22 by a flyback voltage generated at the primary winding 21, which causes a breakdown of the HID bulb 50. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device for lighting a high-intensity discharge lamp (HID bulb) used as a headlamp, an illumination lamp, a streetlight, or the like of an automobile.

  Conventionally, high-intensity discharge lamps such as metal halide bulbs, high-pressure sodium bulbs, and mercury bulbs have the advantages of large luminous flux, high lamp efficiency, and long life. It is used as a streetlight. In view of the advantages, this high-intensity discharge lamp has recently been used as a headlamp for vehicles such as automobiles.

  In order to light up such a high-intensity discharge lamp, a predetermined voltage is applied to the HID bulb at the time of startup, and a high voltage pulse for startup is superimposed on the HID bulb and applied to the HID bulb. It is necessary to cause breakdown (insulation breakdown). For this purpose, the discharge lamp lighting device includes a power source (such as a DC / DC converter) for stably lighting the discharge lamp and an igniter (starting device) for generating a high voltage pulse for starting.

  As one of such discharge lamp lighting devices, a high pressure discharge lamp is lit at a high frequency in the MHz band, and a high voltage for starting near 20 KV can be generated using a diode for a relatively low frequency. A discharge lamp lighting device is known (see, for example, Patent Document 1).

  This high-pressure discharge lamp lighting device comprises an LC resonance device that generates and outputs a high-frequency AC voltage of 1.5 KHz to 1 GHz, and an igniter that generates a starting voltage for the high-pressure discharge lamp based on the output of the LC resonance device. The igniter is generated by an oscillation circuit that generates a voltage having a frequency lower than the high-frequency voltage from the LC resonance device, a drive circuit that boosts the low-frequency voltage to a predetermined voltage, and the drive circuit. The multi-voltage rectifier circuit converts the low frequency starting voltage into a predetermined high voltage DC voltage.

  The high pressure discharge lamp lighting device configured as described above supplies the high frequency voltage generated by the LC resonance device to the high pressure discharge lamp, and superimposes the DC high voltage generated by the igniter on this high frequency voltage. Start lighting. With this configuration, the acoustic resonance phenomenon of the high pressure discharge lamp can be avoided when the AC power source of the high pressure discharge lamp is turned on.

JP 2003-77691 A

  In the above-described conventional discharge lamp lighting device, the part that generates a high voltage is obtained by connecting capacitors that store an intermediate voltage between the lighting voltage and a high voltage sufficient to break down the discharge lamp in series. And a booster circuit for generating an intermediate voltage. Therefore, since the discharge lamp lighting device becomes large, the application is limited, and the development of a small discharge lamp lighting device is desired.

  The present invention has been made to meet the above demand, and a first object is to provide a small and inexpensive discharge lamp lighting device.

  A discharge lamp lighting device according to the present invention includes a switch for intermittently supplying a voltage supplied to both ends of a primary winding of a transformer at a predetermined period, and a high-intensity discharge lamp connected between both ends of a secondary winding of the transformer. The transformer turns ratio between the primary winding and the secondary winding is such that when the switch is disconnected, the voltage induced in the secondary winding by the flyback voltage generated in the primary winding breaks into the high-intensity discharge lamp. It is determined so as to have a value that results in a voltage that causes a down.

  The discharge lamp lighting device according to the present invention includes a first switch that interrupts the voltage supplied to both ends of the primary winding of the first transformer at a predetermined period, and a winding end of the secondary winding of the first transformer. A second transformer to which the winding end of the secondary winding is connected, a second switch for intermittently supplying a voltage supplied to the primary winding of the second transformer at a phase opposite to that of the first switch; A high-intensity discharge lamp connected between the winding start end of the next winding and the winding start end of the second transformer, and the turn ratio between the primary winding and the secondary winding of the first transformer and the second transformer The turn ratio of the primary winding to the secondary winding is a voltage induced in the secondary winding of the first transformer by the flyback voltage generated in the primary winding of the first transformer when the first switch is disconnected. And generated in the primary winding of the second transformer when the second switch is connected. In which the sum of the voltage induced in the second transformer secondary winding by the forward voltage has been determined the value such that the voltage to cause breakdown in the high-intensity discharge lamp so as to have respectively.

  According to the present invention, the voltage induced in the secondary winding by the flyback voltage generated in the primary winding when the switch for interrupting the DC voltage is cut into the voltage causing breakdown in the high-intensity discharge lamp. Thus, since the turn ratio between the primary winding and the secondary winding of the transformer is set, an igniter such as a conventional discharge lamp lighting device is unnecessary. As a result, there is an effect that the discharge lamp lighting device can be configured to be small and inexpensive.

According to the present invention, the voltage induced in the secondary winding of the first transformer by the flyback voltage generated in the primary winding of the first transformer when the first switch to which the DC voltage is supplied is disconnected; The sum of the voltage induced in the secondary winding of the second transformer by the forward voltage generated in the primary winding of the second transformer when the second switch to which the voltage is supplied is connected breaks in the high-intensity discharge lamp. The winding ratio of the primary and secondary windings of the first transformer and the winding ratio of the primary and secondary windings of the second transformer are set so that each has a value that causes a voltage to cause down. Since it is set, there is an effect that a large breakdown voltage can be obtained even if the turn ratio of each transformer is small.
Moreover, a high voltage pulse can be applied to both positive and negative sides, and breakdown can be achieved with a lower voltage.

Embodiment 1 FIG.
1 is a circuit diagram showing a configuration of a discharge lamp lighting device according to Embodiment 1 of the present invention. The discharge lamp lighting device includes a DC power supply 10, a transformer 20, a field effect transistor (hereinafter referred to as “FET”) 30, a control circuit 40, an HID bulb 50, and a capacitor 60.

  The DC power supply 10 is composed of a battery, for example, and outputs a DC voltage of 12V. The DC voltage output from the DC power supply 10 is applied to the primary winding 21 of the transformer 20 via the FET 30.

  The transformer 20 is composed of a high voltage transformer having a turn ratio of the primary winding 21 and the secondary winding 22 of, for example, about 1:30. Since the transformer 20 generates a high voltage on the secondary side, the transformer 20 has a high voltage transformer specification in which the portion of the secondary winding 22 is covered with resin. One terminal of the primary winding 21 of the transformer 20 is connected to the positive terminal of the DC power supply 10, and the other terminal is connected to the drain of the FET 30.

  The FET 30 corresponds to the switch of the present invention. The drain of the FET 30 is connected to the other terminal of the primary winding 21 of the transformer 20 as described above, and the source is connected to the negative terminal of the DC power supply 10. The gate of the FET 30 is connected to the control circuit 40. The FET 30 is turned on or off in response to a control signal from the control circuit 40. Thereby, an alternating voltage is applied to the primary winding 21 of the transformer 20. As this FET 30, it is preferable to use a power MOSFET for high withstand voltage capable of flowing a relatively large current.

  The control circuit 40 generates a control signal that repeatedly turns on and off at a predetermined cycle, and supplies the control signal to the gate of the FET 30. Thereby, the FET 30 repeats the on and off operations at a predetermined cycle.

  The HID bulb 50 is a high-intensity discharge lamp composed of, for example, a metal halide bulb, a high-pressure sodium bulb, a mercury bulb, or the like. One terminal of the HID valve 50 is connected to one terminal of the secondary winding 22 of the transformer 20, and the other terminal is connected to one terminal of the capacitor 60.

  The capacitor 60 is connected in series between the other terminal of the HID valve 50 and the other terminal of the secondary winding 22 of the transformer 20. The capacitor 60 forms a series resonance circuit by using the secondary winding 22 of the transformer 20 as a substitute for a coil.

  If the number of turns of the secondary winding 22 is increased, the inductance of the secondary winding 22 increases and it becomes difficult for the output current to flow, resulting in an adverse effect that the forward voltage during steady lighting increases. However, by adjusting the capacitance of the capacitor 60 to an appropriate value, the apparent inductance can be reduced and the voltage can be stored in the capacitor 60, whereby the voltage applied to the HID valve 50 can be reduced.

  Next, the operation of the discharge lamp lighting device according to Embodiment 1 of the present invention configured as described above will be described with reference to the timing chart shown in FIG.

  When the FET 30 is turned on by a control signal supplied from the control circuit 40, a 12V DC voltage output from the DC power supply 10 is applied to the primary winding 21. Thereby, as shown in FIG. 2 (A), the voltage across the primary winding 21 becomes 12V. Induced by the voltage applied to the primary winding 21, a voltage of 360 V boosted 30 times according to the turns ratio is applied to both ends of the secondary winding 22 as shown in FIG. appear.

  In this state, when the FET 30 is turned off by the control signal supplied from the control circuit 40, the application of the DC voltage from the DC power source 10 to the primary winding 21 is stopped. As a result, a flyback voltage of about 200 V due to the counter electromotive force is generated at both ends of the primary winding 21 as shown in FIG.

  Induced by the flyback voltage generated in the primary winding 21, both ends of the secondary winding 22 of the transformer 20 are boosted 30 times according to the turn ratio as shown in FIG. A high voltage of 6000V appears. This high voltage is sufficient to cause breakdown in the HID bulb 50 for general illumination. The voltage generated in the primary winding 21 and the secondary winding 22 gradually attenuates as time passes.

  The high voltage that appears in the secondary winding 22 due to the above flyback voltage is applied to the HID valve 50. Thereby, breakdown occurs inside the HID bulb 50 and the HID bulb 50 is lit.

  Once the HID bulb 50 is lit, a current flows through the secondary circuit of the transformer 20. As a result, the capacitor 60 is charged and discharged by the voltage of the secondary winding 22 of the transformer 20 as indicated by a broken line in FIG. As a result, an AC voltage lower than when the HID bulb 50 is turned off (when no current flows through the secondary circuit) is applied to the HID bulb 50, and a steady lighting state is entered. In the steady lighting state, the area on the positive side is equal to the area on the negative side, as indicated by hatching in FIG.

  As described above, according to the discharge lamp lighting device according to Embodiment 1 of the present invention, the turn ratio between the primary winding 21 and the secondary winding 22 of the transformer 20 is increased and the secondary voltage is increased by the flyback voltage. Since the high voltage induced in the winding 22 is used as the starting voltage for the HID bulb 50, the igniter provided in the conventional discharge lighting device is not necessary. As a result, since the structure is simplified, a small and inexpensive discharge lamp lighting device can be configured.

Embodiment 2. FIG.
The discharge lamp lighting device according to Embodiment 2 of the present invention is such that a permanent magnet is inserted into a magnetic path formed by a core of a transformer.

  In order to increase the flyback voltage, it is necessary to increase the primary current flowing in the circuit on the primary side of the transformer and store a large amount of magnetic energy in the core of the transformer. However, simply increasing the primary current does not allow the core to be magnetically saturated and store magnetic energy, and the flyback voltage that can be generated is limited.

  Therefore, in the discharge lamp lighting device according to the second embodiment, a permanent magnet is inserted into the magnetic path formed by the core of the transformer so that the magnetic energy is offset to the minus side.

  FIG. 3A is an exploded perspective view showing the structure of the transformer 20 used in the discharge lamp lighting device according to Embodiment 2 of the present invention, and FIG. 3B is a cross-sectional view. In this transformer 20, the open end side of the E-shaped first core 23 and the open end side of the E-shaped second core 24 are opposed to each other, and the projecting portion 25 at the center of the first core 23 and the second core 24 are arranged. The permanent magnet 27 is inserted between the central projecting portion 26 and the primary winding 21 and the secondary winding 22 are wound on the projecting portion 25, the projecting portion 26, and the permanent magnet 27.

  FIG. 4 shows the hysteresis characteristics of the transformer 20 configured as described above. First, in a normal transformer without the permanent magnet 27, the primary current flows only in one direction, so the magnetic field H proportional to the current is always positive, and a hysteresis characteristic that changes only in the first quadrant is obtained.

  On the other hand, in the transformer in which the permanent magnet 27 is inserted and the offset is provided, the magnetic energy stored by the primary current is added from the minus side, and the magnetic saturation is hardly caused by the offset of the permanent magnet 27. It is possible to extract a large flyback energy.

  As described above, according to the discharge lamp lighting device according to Embodiment 2 of the present invention, since the permanent magnet 27 is inserted into the magnetic path formed by the first core 23 and the second core 24 of the transformer 20, The magnetic saturation point of the transformer 20 is increased, and a large amount of magnetic energy can be stored. As a result, since a large flyback voltage can be generated, the HID valve 50 can be easily started.

Embodiment 3 FIG.
In the discharge lamp lighting device according to Embodiment 3 of the present invention, a part of the secondary winding of the transformer is substituted for the inductance of the series resonance circuit.

  In the discharge lamp lighting device according to the first embodiment described above, the secondary winding 22 of the transformer 20 is used as a substitute for a coil, and a capacitor 60 is connected in series to this to constitute a series resonant circuit. Only the inductance component of 22 is insufficient to cancel the AC resistance component of the capacitor 60. Therefore, as shown in FIG. 5, the AC resistance component of the secondary circuit can be reduced by inserting an independent coil 70 for resonance in series with the secondary circuit.

  However, this configuration requires a component called a coil, which hinders the reduction in size and cost of the discharge lamp lighting device. Therefore, in the discharge lamp lighting device according to the third embodiment, as shown in FIG. 6, a part 70 ′ of the secondary winding 22 of the transformer 20 is placed at a position that is not easily affected by the magnetic flux generated by the primary winding 21. Arrangement (winding) is used instead of the coil 70.

  FIG. 7 is a cross-sectional view showing a schematic structure of the transformer 20. In the transformer 20, a primary winding 21 is wound on a core 28, a secondary winding 22 is wound thereon, and a part 70 ′ of the secondary winding 22 is formed by the primary winding 21. It is wound around the portion of the core 28 away from the core. With this configuration, the part 70 ′ of the secondary winding 22 is less affected by the magnetic flux from the primary winding 21 and functions as a coil having a sufficient inductance component.

  As described above, in the discharge lamp lighting device according to the third embodiment, the dedicated coil constituting the series resonance circuit can be omitted, so that the discharge lamp lighting device can be reduced in size and cost.

Embodiment 4 FIG.
The discharge lamp lighting device according to Embodiment 4 of the present invention uses two transformers in series to generate flyback voltages on both the positive and negative sides.

  FIG. 8 is a circuit diagram showing a configuration of a discharge lamp lighting device according to Embodiment 4 of the present invention. The discharge lamp lighting device includes a DC power supply 10, a first transformer 20, a second transformer 80, a first FET 30, a second FET 31, a control circuit 40, an HID bulb 50, and a capacitor 60.

  The DC power supply 10 is composed of a battery, for example, and outputs a DC voltage of 12V. The DC voltage output from the DC power supply 10 is applied to the primary winding 21 of the first transformer 20 and the primary winding 81 of the second transformer 80 via the FET 30.

  The first transformer 20 is composed of a high voltage transformer having a turn ratio of the primary winding 21 and the secondary winding 22 of, for example, about 1:30. The first transformer 20 is the same as the transformer 20 in the first embodiment. The winding start terminal of the primary winding 21 of the first transformer 20 is connected to the positive terminal of the DC power supply 10, and the winding end terminal is connected to the drain of the first FET 30.

  The first FET 30 corresponds to the first switch of the present invention. As described above, the drain of the first FET 30 is connected to the winding end terminal of the primary winding 21 of the first transformer 20, and the source is connected to the negative terminal of the DC power supply 10. The gate of the first FET 30 is connected to the control circuit 40. The first FET 30 is turned on or off in response to the first control signal from the control circuit 40. Thereby, an alternating voltage is applied to the primary winding 21 of the first transformer 20. The first FET 30 is the same as the FET 30 in the first embodiment.

  Similar to the first transformer 20, the second transformer 80 is composed of a high voltage transformer having a turn ratio of the primary winding 81 and the secondary winding 82 of about 1:30. The second transformer 80 is also the same as the transformer 20 in the first embodiment. The winding start terminal of the primary winding 81 of the second transformer 80 is connected to the positive terminal of the DC power supply 10, and the winding end terminal is connected to the drain of the second FET 31.

  The second FET 31 corresponds to the second switch of the present invention. The drain of the second FET 31 is connected to the winding end terminal of the primary winding 81 of the second transformer 80 as described above, and the source is connected to the negative terminal of the DC power supply 10. The gate of the second FET 31 is connected to the control circuit 40. The second FET 31 is turned on or off in response to the second control signal from the control circuit 40. Thereby, an alternating voltage is applied to the primary winding 81 of the second transformer 80. The second FET 31 is the same as the FET 30 in the first embodiment.

  The control circuit 40 generates a first control signal and a second control signal that repeatedly turn on and off at a predetermined period, and supplies the first control signal and the second control signal to the gate of the first FET 30 and the gate of the second FET, respectively. The second control signal is a signal in which the phase of the first control signal is reversed (shifted by 180 degrees). As a result, the first FET 30 and the second FET 31 are exclusively turned on and off in a predetermined cycle.

  The secondary winding 22 of the first transformer 20 and the secondary winding 82 of the second transformer 80 are connected in series so as to have opposite polarities. Specifically, the winding end terminal of the secondary winding 22 of the first transformer 20 and the winding end terminal of the secondary winding 82 of the second transformer 80 are connected.

  The HID valve 50 is the same as that in the first embodiment. One terminal of the HID valve 50 is connected to the winding start terminal of the secondary winding 22 of the first transformer 20, and the other terminal is connected to one terminal of the capacitor 60.

  The capacitor 60 is connected in series between the other terminal of the HID valve 50 and the winding start terminal of the secondary winding 22 of the second transformer 80. The capacitor 60 forms a series resonance circuit using the secondary winding 22 of the first transformer 20 and the secondary winding 80 of the second transformer 80 as substitutes for coils.

  Next, the operation of the discharge lamp lighting device according to Embodiment 4 of the present invention configured as described above will be described with reference to the timing chart shown in FIG.

  When the first FET 30 is turned on by the first control signal supplied from the control circuit 40, a 12V DC voltage output from the DC power supply 10 is applied to the primary winding 21 of the first transformer 20. As a result, as shown in FIG. 9A, the voltage across the primary winding 21 becomes 12V. Induced by the voltage applied to the primary winding 21, a voltage of 360 V boosted 30 times according to the turn ratio appears at both ends of the secondary winding 22.

  In this state, when the first FET 30 is turned off by the first control signal supplied from the control circuit 40, the application of the DC voltage from the DC power source 10 to the primary winding 21 is stopped. As a result, a flyback voltage of about 200 V due to the counter electromotive force is generated at both ends of the primary winding 21 as shown in FIG.

  Induced by the flyback voltage generated in the primary winding 21, a high voltage of 6000 V, which is boosted 30 times according to the turn ratio, appears at both ends of the secondary winding 22 of the first transformer 20. Therefore, when viewed from one terminal of the HID valve 50, as shown in FIG. 9C, a positive voltage from a predetermined voltage (0V) to 6360V is applied. Thereafter, the high voltage appearing at both ends of the primary winding 21 and the secondary winding 22 gradually attenuates as time passes.

  On the other hand, the second FET 31 is turned on by the second control signal supplied from the control circuit 40. As a result, a DC voltage of 12V output from the DC power supply 10 is applied to the primary winding 81 of the second transformer 80. As a result, as shown in FIG. 9B, the voltage across the primary winding 81 becomes 12V. Induced by the voltage applied to the primary winding 81, a voltage of 360V, which is boosted 30 times according to the turn ratio, appears at both ends of the secondary winding 82.

  In this state, when the second FET 31 is turned off by the second control signal supplied from the control circuit 40, the application of the DC voltage from the DC power source 10 to the primary winding 81 is stopped. As a result, a flyback voltage of about 200 V due to the counter electromotive force is generated at both ends of the primary winding 81 as shown in FIG. 9B.

  Induced by the flyback voltage generated in the primary winding 21, a high voltage of 6000 V, which is boosted 30 times according to the turn ratio, appears at both ends of the secondary winding 82 of the second transformer 80. Therefore, when viewed from one terminal of the HID valve 50, as shown in FIG. 9C, a negative voltage from a predetermined voltage (0V) to 6360V is applied. Thereafter, the high voltage appearing at both ends of the primary winding 81 and the secondary winding 82 gradually attenuates as time passes.

  The high voltage that changes from −6360 V to +6360 V appearing in the secondary winding 22 of the first transformer 20 and the secondary winding 82 of the second transformer 80 due to the flyback voltage is applied to the HID valve 50. The Thereby, breakdown occurs inside the HID bulb 50 and the HID bulb 50 is lit.

  Once the HID bulb 50 is lit, a current flows through the secondary circuit of the first transformer 20 and the second transformer 80. As a result, the capacitor 60 is charged / discharged by the voltage appearing in the secondary winding 22 of the first transformer 20 and the secondary winding 82 of the second transformer 80. As a result, an AC voltage lower than when the HID bulb 50 is turned off (when no current flows through the secondary circuit) is applied to the HID bulb 50, and a steady lighting state is entered.

  As described above, according to the discharge lamp lighting device according to the fourth embodiment of the present invention, the first transformer 20 and the second transformer 80 that are the same as the transformer having the large turn ratio used in the first embodiment are used. The secondary winding 22 and the secondary winding 82 are connected in series so that the polarities are reversed, and the first transformer and the second transformer are alternately operated. Therefore, the igniter provided in the conventional discharge lighting device is not required, and the structure is simplified, so that a small and inexpensive discharge lamp lighting device can be configured.

In addition, since a high voltage due to the flyback voltage is generated on both the positive side and the negative side, the two electrodes inside the HID valve 50 are always in the same state if the high voltage has a positive and negative symmetrical waveform. Thus, it is possible to avoid any one-sided deterioration. As a result, the life of the HID valve can be extended. In addition, even during steady lighting, the same voltage is applied when switching the polarity, so the heat generated by the electrons and ions received by each electrode is also equal, and the continuity of current at the timing of switching the polarity is the same and stable. Can be turned on.
Further, by applying a high voltage pulse on both the positive and negative sides, it is possible to break down with a lower voltage.

It is a circuit diagram which shows the structure of the discharge lamp lighting device which concerns on Embodiment 1 of this invention. It is a timing chart for demonstrating operation | movement of the discharge lamp lighting device which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the transformer used with the discharge lamp lighting device which concerns on Embodiment 2 of this invention. It is a figure for demonstrating the characteristic of the transformer used with the discharge lamp lighting device which concerns on Embodiment 2 of this invention. It is a figure for demonstrating the discharge lamp lighting device which concerns on Embodiment 3 of this invention. It is a circuit diagram which shows the structure of the discharge lamp lighting device which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the structure of the discharge lamp lighting device which concerns on Embodiment 3 of this invention. It is a circuit diagram which shows the structure of the discharge lamp lighting device which concerns on Embodiment 4 of this invention. It is a timing chart for demonstrating operation | movement of the discharge lamp lighting device which concerns on Embodiment 4 of this invention.

Explanation of symbols

  10 DC power supply, 20 transformer, first transformer, 21, 81 primary winding, 22, 82 secondary winding, 23 first core, 24 second core, 25, 26 protrusion, 27 permanent magnet, 28 core, 30 FET (switch), 1st FET (1st switch), 31 2nd FET (2nd switch), 40 control circuit, 50 HID bulb (high intensity discharge lamp), 60 capacitor, 70 coil, 70 ' Part, 80 second transformer.

Claims (4)

With a transformer
A switch for interrupting the DC voltage supplied to both ends of the primary winding of the transformer at a predetermined period;
A high-intensity discharge lamp connected between both ends of the secondary winding of the transformer,
The turn ratio of the primary winding to the secondary winding of the transformer is such that the voltage induced in the secondary winding by the flyback voltage generated in the primary winding when the switch is cut off is the high luminance discharge. A discharge lamp lighting device characterized by having a value that is a voltage causing breakdown of the electric lamp.   The discharge lamp lighting device according to claim 1, wherein a permanent magnet is inserted in a magnetic path formed by a core around which the primary winding and secondary winding of the transformer are wound. A capacitor connected between one end of the secondary winding of the transformer and the high-intensity discharge lamp;
A part of the secondary winding of the transformer is wound around the core at a position where the influence of the magnetic flux of the primary winding is small, and a series resonance circuit is constituted by the inductance composed of a part of the secondary winding and the capacitor. The discharge lamp lighting device according to claim 1. A first transformer;
A first switch that intermittently interrupts a DC voltage supplied to both ends of the primary winding of the first transformer;
A second transformer in which the winding end of the secondary winding is connected to the winding end of the secondary winding of the first transformer;
A second switch for intermittently connecting a DC voltage supplied to a primary winding of the second transformer in a phase opposite to that of the first switch;
A high intensity discharge lamp connected between the winding start end of the secondary winding of the first transformer and the winding start end of the second transformer;
The turns ratio between the primary winding and the secondary winding of the first transformer and the turns ratio between the primary winding and the secondary winding of the second transformer are determined when the first switch is disconnected. A voltage induced in the secondary winding of the first transformer by a flyback voltage generated in the primary winding of the first transformer and a forward voltage generated in the primary winding of the second transformer when the second switch is connected. The discharge lamp lighting device according to claim 1, wherein a sum of a voltage induced in a secondary winding of the second transformer has a value that causes a breakdown voltage in the high-intensity discharge lamp.

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