JP4984062B2 - Discharge lamp lighting device - Google Patents

Description

  The present invention relates to a discharge lamp lighting device for lighting a discharge lamp such as an HID lamp (High Intensity Discharge Lamp) used for an automobile headlamp.

  Conventionally, as a discharge lamp lighting device for lighting a discharge lamp such as an HID lamp, a DC booster circuit (DC / DC converter) that boosts a DC voltage input from a DC power source such as a battery, and an output of the DC booster circuit are used. An inverter circuit capable of converting to alternating current; and a starting circuit for applying a starting high-pressure pulse for starting discharge of the discharge lamp to the discharge lamp at the start of lighting of the discharge lamp, from the DC booster circuit through the inverter circuit It is generally known that the electric lamp is supplied with electric power to turn on the discharge lamp (see, for example, Patent Documents 1 and 2).

  FIG. 5 is a diagram showing a circuit configuration of a conventional general discharge lamp lighting device. In the figure, 100 is a DC power source such as an automobile battery, 101 is a DC boosting circuit (DC / DC converter), 102 is an inverter circuit, 103 is a starting circuit, 104 is an HID lamp as a discharge lamp, and 105 is a DC boosting circuit. 101 is a controller (control circuit) that controls the inverter 101 and the inverter circuit 102. Further, in order to control the DC booster circuit 101 and the inverter circuit 102 by the controller 105, a voltage generated by the HID lamp 104 (hereinafter sometimes referred to as a lamp voltage) is provided between the DC booster circuit 101 and the inverter circuit 102. Voltage detecting voltage dividing resistors 106 and 107 for detecting the current and a current detecting resistor 108 for detecting a current flowing in the HID lamp 104 (hereinafter sometimes referred to as a lamp current) are interposed, A start-up auxiliary circuit 109 for preventing a drop in lamp current immediately after the start of the HID lamp 104 is provided.

  In the illustrated example, the DC booster circuit 101 is a PWM control type DC / DC converter configured by connecting a semiconductor switch element 110, a booster transformer 111, a rectifying diode 112, and a smoothing capacitor 113 as illustrated. The DC booster circuit 101 turns the semiconductor switch element 110 ON / OFF at a predetermined cycle in a state where a DC voltage is input from the DC power supply 100 to a series circuit of the semiconductor switch element 110 and the primary winding of the boost transformer 111. As a result, a high voltage pulse voltage is generated in the secondary winding of the step-up transformer 111. Then, this pulse voltage is rectified and smoothed by a rectifying diode 112 and a smoothing capacitor 113 connected in series to the secondary winding, respectively, thereby boosting the DC voltage of the DC power source 100 and outputting a direct current. Generate voltage. The output voltage of the DC booster circuit 101 is operated by the controller 105 by controlling the ON / OFF duty of the semiconductor switch element 110 (PWM control of the semiconductor switch element 110). In the state where the output current is 0), an output voltage of about 400 V at maximum can be generated.

  The inverter circuit 102 is configured by connecting four semiconductor switch elements 102a, 102b, 102c, and 102d in a bridge manner as shown in the figure, and the controller 105 controls ON / OFF of these semiconductor switch elements 102a to 102d. Thus, the direct current input from the direct current booster circuit 101 can be converted into alternating current and output. Note that by maintaining one of the pair of semiconductor switch elements 102a and 102d and the pair of 102b and 102c in the ON state and maintaining the other in the OFF state, the inverter circuit 102 is connected to the DC boost circuit 102. It is also possible to output a DC voltage having a magnitude substantially equal to that of the output voltage and having the same polarity or opposite polarity as the output voltage.

  The starting circuit 103 includes a series circuit of a diode 114, a resistor 115 and a capacitor 116, a parallel circuit of a thyristor 117 and a diode 118, a starting transformer 119, a trigger circuit 120 of the thyristor 117, an inverter circuit 102, and an HID lamp 104. And connected as shown in the figure. In this start-up circuit 103, before the HID lamp 104 is turned on, the trigger circuit 120 turns on the thyristor 117 according to the voltage charged from the DC booster circuit 101 through the diode 114 and the resistor 115 to the capacitor 116. The charged electric charge of the capacitor 116 is instantaneously supplied to the primary winding of the starting transformer 119. As a result, a starting high-pressure pulse is excited in the secondary winding of the starting transformer 119 connected in series with the HID lamp 104, and this starting high-pressure pulse is applied to the HID lamp 104.

  The voltage detection voltage dividing resistors 106 and 107 are connected in series, and the output voltage of the DC booster circuit 101 is applied to both ends thereof. Then, a voltage generated in the resistor 107 of the voltage detection voltage dividing resistors 106 and 107 (which is proportional to the output voltage of the DC booster circuit 101) is output to the controller 105 as a lamp voltage detection signal of the HID lamp 104. To do. The current detection resistor 108 generates a voltage proportional to the lamp current of the HID lamp 104 and outputs this voltage to the controller 105 as a lamp current detection signal. The start-up auxiliary circuit 109 is constituted by a series circuit of a resistor 121 and a capacitor 122, and an output voltage of the DC booster circuit 101 is applied to both ends thereof via a current detection resistor 108. Supplementally, since a starting high voltage pulse of about 25 kV is applied to the HID lamp 104 as described later, it is difficult to detect the lamp voltage of the HID lamp 104 directly in terms of circuit. The output voltage of the DC booster circuit 101 is not the same as that of the HID lamp 104 although there is a slight error due to the ON resistance of the semiconductor switch elements 102a to 102d of the inverter circuit 102 except when the high-voltage pulse for starting is applied. It is roughly equivalent to voltage. Therefore, a detection signal (voltage signal proportional to the output voltage of the DC booster circuit 101) by the voltage detection voltage dividing resistors 106 and 107 is used as a lamp voltage detection signal of the HID lamp 104.

  The operation control of the HID lamp 104 (control for starting the discharge / lighting of the HID lamp 104 and performing stable lighting stably) by the discharge lamp lighting device having the above configuration is performed as follows. FIGS. 6A and 6B are timing charts illustrating the change over time in the lamp voltage and lamp current in this operation control.

  First, in a state where a DC voltage (for example, about 12 V) is input from the DC power supply 100 to the DC booster circuit 101, the controller 105 controls the set of semiconductor switch elements 102a and 102d of the inverter circuit 102 to the ON state, and the semiconductor switch The set of the elements 102b and 102c is controlled to be in the OFF state. Further, the controller 105 performs PWM control of the semiconductor switch element 110 of the DC boost circuit 101 to boost the output voltage of the DC boost circuit 101 to a maximum of about 400V. At this time, the output voltage of the DC booster circuit 101 is applied to the HID lamp 104 via the inverter circuit 102 (period t1 to t2 in FIG. 6A).

  During this period, the capacitor 122 of the startup auxiliary circuit 109 is charged, and further, the capacitor 116 of the startup circuit 103 is charged. When the charging voltage of the capacitor 116 of the starting circuit 103 exceeds a predetermined value, the trigger circuit 120 turns on the thyristor 117 (time t2 in FIGS. 6A and 6B). As a result, the electric charge of the capacitor 116 is instantaneously discharged through the primary winding of the starting transformer 119 and the thyristor 117, and a high-voltage starting pulse having a peak value of about 25 kV is generated in the secondary winding of the starting transformer 119. To do. This starting high-pressure pulse is applied to the HID lamp 104.

  FIG. 7 is a graph showing an example of the waveform of the starting high-voltage pulse. In the start-up circuit 103, a diode 118 in the reverse direction to the forward direction of the thyristor 117 is connected in parallel to the thyristor 117 so that an excessive reverse voltage acts on the thyristor 117 and the thyristor 117 is not damaged. For this reason, the waveform of the starting high-voltage pulse is a simple damped oscillation as shown in FIG.

  The application of the starting high-voltage pulse starts discharging and lighting of the HID lamp 104, and an instantaneous inrush current flows from the DC booster circuit 101 to the HID lamp 104 through the inverter circuit 102. At this time, an inrush current flows through the HID lamp 104, whereby the capacitor 113 at the output of the DC booster circuit 101 is rapidly discharged. For this reason, the lamp current immediately after startup of the HID lamp 104 (immediately after application of the startup high-pressure pulse) rapidly decreases as shown in FIG. In this case, if the start-up auxiliary circuit 109 is omitted, the lamp current is excessively decreased (an excessive decrease in the lamp current occurs) as shown by a broken line in FIG. 6B, and the HID lamp 104 is extinguished. Prone to occur. The start-up auxiliary circuit 109 is for preventing this, and by discharging the charge of the capacitor 122 to the HID lamp 104 via the resistor 121 (this is slightly delayed from the time of applying the start-up high-pressure pulse). The excessive reduction of the lamp current is suppressed, and the discharge / lighting of the HID lamp 104 is continued. Immediately after the start of the HID lamp 104 (so-called cold start) with the HID lamp 104 cooled, the lamp voltage generated in the HID lamp 104 is about 20 V, so that the lamp voltage is the high voltage pulse for starting. After application of, it decreases.

  On the other hand, immediately after activation of the HID lamp 104, the temperature of the electrode is low, and the discharge of the HID lamp 104 tends to become unstable. Therefore, in order to quickly raise the temperature of the electrode of the HID lamp 104 and stabilize the discharge of the HID lamp 104, a period until a predetermined time elapses from the start of activation of the HID lamp 104 (FIG. 6A, In a period from time t2 to t4 in (b) (hereinafter referred to as a discharge stabilization period), a predetermined time (which is sufficiently longer than the cycle of the AC lighting frequency (for example, 400 Hz) during steady lighting of the HID lamp 104) For example, the inverter circuit 102 is controlled by the controller 105 so that positive and negative DC currents are sequentially supplied to the HID lamp 104 in increments of 10-20 ms. That is, in the discharge stabilization period, during the period from time t2 to t3 in FIGS. 6A and 6B, the semiconductor switch elements 102a and 102d of the inverter circuit 102 are controlled to be ON, and the semiconductor switch elements 102b, By controlling 102c to OFF, a positive lamp current is caused to flow through the HID lamp 104, and during the subsequent period from time t3 to t4, the semiconductor switch elements 102a and 102d of the inverter circuit 102 are controlled to be OFF, and the semiconductor By controlling the switch elements 102b and 102c to be ON, a negative lamp current is caused to flow through the HID lamp 104. In these periods, the lamp current or the power supplied to the HID lamp 104 (hereinafter referred to as lamp power) according to the lamp voltage detection signal input to the controller 105 via the voltage detection voltage dividing resistors 106 and 107. Target value) is determined. The target value is a target value of an appropriate lamp current or lamp power for raising the temperature of the electrode of the HID lamp 104 at an early stage and stabilizing the discharge of the HID lamp 104. Then, the direct current booster circuit is set so that the lamp current detected via the current detection resistor 108 or the lamp power obtained from the detected value of the lamp current and the detected value of the lamp voltage matches the target value. The output of 101 is feedback controlled by the controller 105 via the semiconductor switch element 110.

  At the end of the discharge stabilization period, the electrode of the HID lamp 104 is sufficiently heated, so that even after the HID lamp 104 is turned on, the HID lamp 104 is not turned off and discharged and lit. Can be performed stably. Therefore, when the discharge stabilization period ends (time t4 in FIGS. 6A and 6B), next, a set of semiconductor switch elements 102a and 102d of the inverter circuit 102 and a set of semiconductor switch elements 102b and 102c. Are alternately controlled by the controller 105 at a frequency of about 400 Hz. Thereby, AC lighting of the HID lamp 104 is started.

  In this AC lighting, a target value of lamp current or lamp power is set according to the lamp voltage detected through the voltage detection voltage dividing resistors 106 and 107 and detected through the current detection resistor 108. The controller 105 outputs the output of the DC booster circuit 101 via the semiconductor switch element 110 so that the lamp power or the lamp power obtained from the detected value of the lamp current and the detected value of the lamp voltage becomes the target value. Feedback controlled.

  In this case, immediately after the cold start of the HID lamp 104, the luminous flux (light quantity) of the HID lamp 104 is lower than that at the time of stable lighting, so that the luminous flux of the HID lamp 104 needs to be raised immediately. In general, when the HID lamp 104 is continuously turned on, the lamp voltage increases and the luminous flux increases as the temperature of the arc tube of the HID lamp 104 increases. Therefore, the target value of the lamp current or lamp power for AC lighting of the HID lamp 104 is a warm-up current that is several times the rated current of the HID lamp 104 (lamp current during stable lighting) in a state where the lamp voltage is relatively low. It is set according to the detected value of the lamp voltage so as to flow through the lamp 104. For example, as illustrated in FIG. 8, the target value of the lamp current or lamp power in AC lighting is set according to the detected value of the lamp voltage. The example of FIG. 8 is an example in which an HID lamp enclosing mercury is used as the HID lamp 104.

By controlling the lamp current or lamp voltage during AC lighting of the HID lamp 104 in this way, the lamp voltage gradually increases as shown in FIG. 6A, and finally stable at a voltage of about 85V. To do. Further, as shown in FIG. 6B, the lamp current gradually decreases and finally stabilizes at a current of about 0.4 A.
JP 11-329768 A JP 2000-36393 A

  By the way, conventionally, an HID lamp encapsulating mercury (hereinafter sometimes referred to as a mercury encapsulated HID lamp) has been generally used. However, in recent years, it is not necessary to enclose mercury for environmental protection or the like. HID lamps (hereinafter sometimes referred to as mercury-free HID lamps) have been developed, and there is an increasing demand for using them instead of mercury-filled HID lamps.

  This mercury-free HID lamp can be lit on a trial basis in the same manner as the mercury-filled HID lamp using the above-described conventional discharge lamp lighting device.

  However, in the mercury-free HID lamp, the maximum warm-up current required immediately after its startup is larger than that in the mercury-filled free HID lamp, and in order to obtain a luminous flux equivalent to that of the mercury-filled HID lamp even during stable lighting, The lamp current is about twice that of a mercury-filled HID lamp. Then, since the necessary lamp current becomes larger than that of the mercury-filled HID lamp, the voltage caused by the ON resistance of the semiconductor switch elements 102a to 102d of the inverter circuit 102 and the resistance of the primary winding of the starting transformer 119 is obtained. The magnitude of the descent and its variation increase. For this reason, an error of the voltage detected through the voltage detection voltage dividing resistors 106 and 107 (= the output voltage of the DC booster circuit 101) with respect to the actual lamp voltage increases.

  Furthermore, the initial lamp voltage after starting the mercury-free HID lamp (the lamp voltage near the start time of AC lighting) is about 25 V, which is about the same as the initial lamp voltage (about 20 V) of the mercury-filled HID lamp. However, the lamp voltage during stable lighting is about 42V, which is about half of the lamp voltage (about 85V) during stable lighting of the mercury-filled HID lamp. Therefore, the change width of the lamp voltage of the mercury-free HID lamp is significantly smaller than the change width of the lamp voltage of the mercury-filled HID lamp.

  As described above, when the mercury-free HID lamp is used, the variation range of the lamp voltage is smaller than when the mercury-filled HID lamp is used, and the error of the detected value of the lamp voltage with respect to the actual lamp voltage. Therefore, it becomes difficult to suitably control the operation of the HID lamp as described above, and in some cases, the HID lamp may be extinguished due to rapid life deterioration.

  In addition, the mercury-free HID lamp requires a larger lamp current than the mercury-filled HID lamp. Therefore, when the mercury-free HID lamp is operated with the conventional discharge lamp lighting device as shown in FIG. Rather than operating the lamp, it is caused by resistance components such as the DC resistance of the secondary winding of the step-up transformer 111 of the DC boost circuit 101 of the discharge lamp lighting device and the ON resistance of the semiconductor switch elements 102a to 102d of the inverter circuit 102. The heat generated by the Joule heat increases, and the circuit efficiency of the discharge lamp lighting device decreases.

  In order to eliminate the above inconvenience, for example, it is conceivable to reduce the maximum output voltage of the DC booster circuit 101. If the maximum output voltage of the DC booster circuit 101 is lowered, the required breakdown voltage of the semiconductor switch elements 102a to 102d of the inverter circuit 102 is reduced, and the ON resistance thereof can be reduced. Furthermore, since it is possible to reduce the DC resistance by reducing the number of secondary windings of the step-up transformer 111 of the DC boost circuit 101, it is considered that the heat generation of the discharge lamp lighting device can be reduced. It is done.

  However, in the above-described conventional discharge lamp lighting device, when the maximum output voltage of the DC booster circuit 101 is lowered, in other words, the voltage applied from the DC booster circuit 101 to the HID lamp before starting the lighting of the HID lamp is 400 V of the prior art. The inventors of the present application have found that if the temperature is lower than about 1, the discharge of the HID lamp does not start stably, and an HID lamp start-up error is likely to occur.

  Then, as a result of the inventor of the present application repeating various studies on the cause, in the conventional discharge lamp lighting device, the pulse width of the start high voltage pulse applied from the start circuit 103, that is, the start high voltage pulse It has been found that the application time to the HID lamp is too short, and this is one factor that destabilizes the discharge start of the HID lamp when the maximum output voltage of the DC booster circuit is lower than 400V.

  The present invention has been made in view of such a background, and the pulse width of the starting high-pressure pulse applied to the discharge lamp at the start of lighting of the discharge lamp can be expanded by a simple method. An object of the present invention is to provide a discharge lamp lighting device capable of smoothly starting discharge / lighting at the start of a discharge lamp such as an HID lamp even when the maximum output voltage is lowered.

  In order to achieve such an object, a discharge lamp lighting device of the present invention boosts a DC voltage input from a DC power supply, and a DC boost circuit that inputs the boosted output voltage to the discharge lamp via an inverter circuit; A starting circuit for receiving a power supply from the DC booster circuit and applying a starting high-pressure pulse for starting the lighting of the discharge lamp to the discharge lamp, and at the start of lighting of the discharge lamp, A discharge lamp lighting device that starts a lighting of a discharge lamp by applying a starting high-pressure pulse from the starting circuit to the discharge lamp in a state where a DC voltage of a predetermined value is applied to the discharge lamp from the booster circuit via an inverter circuit The starter circuit includes a starter transformer having a secondary winding connected in series with the discharge lamp between a pair of output terminals of the inverter circuit, and the DC booster circuit before the start of lighting of the discharge lamp. And a starting capacitor that is charged by the supply of electric power, and is connected in series with the primary winding of the starting transformer between both ends of the starting capacitor, and the charging voltage of the starting capacitor is a predetermined breakdown voltage. And a breakdown element that autonomously conducts when the voltage exceeds the voltage, and the conduction of the breakdown element instantaneously discharges the charge of the starting capacitor via the primary winding of the starting transformer. Thus, the circuit is configured to excite the high-voltage pulse for start-up in the secondary winding of the start-up transformer, and the start-up transformer includes the high-voltage pulse for start-up excited in the secondary winding. The waveform is excited in the secondary winding of the starting transformer due to the instantaneous flow of current from the starting capacitor to the primary winding of the starting transformer. And the secondary winding of the starting transformer is excited by the back electromotive force due to the fact that current does not flow in the primary winding of the starting transformer immediately after the generation of the first high-pressure pulse. The two high-voltage pulse components are combined to form a damped oscillation waveform, and the two high-voltage pulse components are overlapped with a phase shift to form a pulse portion of the damped oscillation waveform. It is a transformer in which the connectivity of at least one of the wires is adjusted (first invention).

  According to the first aspect of the present invention, the waveform of the starting high-voltage pulse excited by the secondary winding of the starting transformer of the starting circuit is instantaneously transferred from the starting capacitor to the primary winding of the starting transformer. A first high-voltage pulse component excited in the secondary winding of the starting transformer due to current flowing, and a current in the primary winding of the starting transformer immediately after the generation of the first high-voltage pulse Resulting in a damped oscillation waveform obtained by synthesizing the second high-voltage pulse component excited by the back electromotive force in the secondary winding of the starting transformer, and the high-voltage pulse components are By overlapping with the phases shifted, a waveform is formed in which a pulse portion of the damped oscillation waveform is formed. For this reason, each pulse portion of the starting high-voltage pulse (a pulse portion corresponding to a half cycle in the damped oscillation waveform of the starting high-voltage pulse) is overlapped by shifting the phases of the first high-voltage pulse component and the second high-voltage pulse component. Thus, the pulse width is larger than the pulse width of each high-voltage pulse component, and the width of each pulse portion of the starting high-voltage pulse can be increased. For this reason, at the start of lighting of the discharge lamp, the time during which the high voltage is continuously applied can be lengthened. As a result, even when the DC voltage of the predetermined value applied from the DC booster circuit to the discharge lamp before the start of lighting of the discharge lamp is relatively low, the discharge lamp can be stably discharged in response to the application of the starting high-pressure pulse. Can be started.

  Therefore, according to the first invention, the pulse width of the starting high-pressure pulse applied to the discharge lamp at the start of lighting of the discharge lamp can be expanded by a simple method. Even when the DC voltage of the predetermined value to be applied, that is, the maximum output voltage of the DC booster circuit is made lower than before, discharge / lighting at the start of a discharge lamp such as an HID lamp can be started smoothly. it can. Since the maximum output voltage of the DC booster circuit can be made lower than before, the required withstand voltage of the switch element of the inverter circuit is reduced, and the ON resistance (resistance value when conducting) of the switch element is reduced. Can be made smaller than before, and the number of turns of the secondary winding of the step-up transformer provided in the DC booster circuit can be made smaller than before, and the resistance value (DC resistance value) of the secondary winding can be made smaller. As a result, the heat generation of the discharge lamp lighting device of the first invention can be suppressed, and the circuit efficiency of the discharge lamp lighting device can be increased. In addition, the maximum output voltage of the DC booster circuit is lower than before, and the required withstand voltage of circuit components such as rectifier diodes and switch elements of the inverter circuit provided on the secondary winding side of the boost transformer of the DC booster circuit Therefore, it is possible to reduce the size and cost of each of those components. As a result, the discharge lamp lighting device can be reduced in size and cost.

  Furthermore, since the ON resistance of the switching element of the inverter circuit can be reduced, the difference between the output voltage of the DC booster circuit and the actual generated voltage of the discharge lamp can be reduced during lighting of the discharge lamp. For this reason, as with conventional discharge lamp lighting devices, the output voltage of the DC booster circuit is detected to indicate the voltage generated by the discharge lamp, and the current or power of the discharge lamp is controlled according to the detected voltage. In this case, the control can be suitably performed.

  In the first invention, the discharge lamp may be either the HID lamp in which mercury is sealed (mercury-filled HID lamp) or the HID lamp in which mercury is not sealed (mercury-free HID lamp). The effect of can be produced. In particular, when a mercury-free HID lamp is used, the circuit efficiency can be significantly increased as compared with the conventional discharge lamp lighting device, and the current and power of the lamp during AC lighting of the HID lamp can be increased. Control can be suitably performed.

  In the first invention, the breakdown element of the start-up circuit is an element having a breakdown voltage higher than the voltage of the predetermined value applied to the discharge lamp from the DC booster circuit before starting the lighting of the discharge lamp. And the DC boost circuit includes a primary winding to which a DC voltage of the DC power supply is periodically applied, and includes a first secondary winding and a second secondary winding. And a first rectifier diode and a first smoothing capacitor connected in series between both ends of the first secondary winding of the step-up transformer, and one end of the second secondary winding. And a second rectifying diode that outputs a DC voltage to be input to the inverter circuit from one end on the high potential side of the first smoothing capacitor of the DC boosting circuit, and the second rectifying diode. From diode It is preferable to output a DC voltage to charge the starting capacitor of the serial start circuit (second invention).

  In the second aspect of the invention, an element having a breakdown voltage higher than the predetermined voltage applied from the DC booster circuit to the discharge lamp before the start of lighting of the discharge lamp is used as a breakdown element of the startup circuit. By using it, the peak value of the pulse voltage excited by the primary winding of the starting transformer according to the conduction of the breakdown element can be increased. As a result, it is possible to reduce the number of turns of the secondary winding required to excite the starting high-voltage pulse having a required peak value for starting the discharge lamp to the secondary winding of the starting transformer. It becomes. As a result, the resistance value (DC resistance value) of the secondary winding can be reduced to further reduce the heat generated by the discharge lamp lighting device during continuous lighting of the discharge lamp, and the output voltage of the DC booster circuit and the discharge lamp. The difference from the actual generated voltage can be further reduced. As a result, the circuit efficiency of the discharge lamp lighting device can be further increased, and the current and power of the discharge lamp can be suitably controlled.

  In this case, the breakdown voltage required for the conduction of the breakdown element is higher than the predetermined voltage applied from the DC booster circuit to the discharge lamp before the discharge lamp starts lighting. By providing the circuit with the second secondary winding and a second rectifying diode connected thereto, the start-up capacitor of the start-up circuit from the second secondary winding side of the DC boost circuit Can be supplied to the start-up capacitor without hindrance by charging a voltage higher than the breakdown voltage required for the conduction of the breakdown element.

  In the second invention, it is preferable that the other end of the second secondary winding of the DC booster circuit is connected to one end on the high potential side of the first smoothing capacitor (third invention). ).

  According to the third aspect of the present invention, when the second rectifying diode is turned off, the voltage applied to the second rectifying diode from the second secondary winding is equal to the voltage of the smoothing capacitor. Therefore, even if the breakdown voltage of the breakdown element is a relatively high voltage, it is possible to prevent the required breakdown voltage of the second rectifying diode from becoming excessive. As a result, the size and cost of the second rectifying diode can be reduced.

  In the second or third aspect of the invention, a relatively high DC voltage is supplied from the second secondary winding side of the DC booster circuit to the starting capacitor of the starting circuit. High-frequency noise is radiated between the booster circuit and the startup circuit, which may affect the operation of a circuit (such as an inverter circuit) from the DC booster circuit to the discharge lamp. Therefore, in the second or third invention, a second smoothing capacitor for smoothing the DC voltage output from the second rectifying diode of the DC booster circuit is provided in the vicinity of the second rectifying diode. It is preferable to connect to the second rectifying diode (fourth invention).

  According to the fourth aspect of the invention, since the ripple component of the DC voltage output from the second rectifying diode can be reduced by the second smoothing capacitor, the radiation of the high frequency noise can be reduced. In addition, since the ripple component of the DC voltage output from the second rectifying diode is reduced, the charging efficiency of the starting capacitor of the starting circuit can be increased.

  An embodiment of a discharge lamp lighting device of the present invention will be described with reference to FIGS.

  First, the circuit configuration of the discharge lamp lighting device of the present embodiment will be described with reference to FIG. FIG. 1 is a diagram showing the circuit configuration. As shown in the figure, the discharge lamp lighting device 1 of the present embodiment is capable of outputting a DC booster circuit (DC / DC converter) 3 that boosts a DC voltage input from a DC power supply 2 and converting DC to AC. An inverter circuit 4, a starting circuit 6 for applying a starting high-pressure pulse to the discharge lamp 5, a controller (control circuit) 7 for controlling the DC boosting circuit 3 and the inverter circuit 4, a first starting auxiliary circuit 8 and a second starting And an auxiliary circuit 9. In addition, the discharge lamp lighting device 1 includes a pair of voltage detection voltage dividing resistors 10 and 11 as voltage detection means for detecting the voltage generated by the discharge lamp 5 and detects the current flowing through the discharge lamp 5. As a current detection means, a current detection resistor 12 is provided.

  In the present embodiment, the DC power source 2 is, for example, a car battery, and its output voltage is about 12V. The discharge lamp 5 is, for example, an HID lamp for an automobile headlamp. Hereinafter, the discharge lamp 5 is referred to as an HID lamp 5.

  The DC booster circuit 3 includes a pair of input terminals 13a and 13b, a step-up transformer 14 having one primary winding 14a and two secondary windings 14b and 14c, a semiconductor switching element 15, and two rectifying diodes. 16 and 17, a smoothing capacitor 18, and three output terminals 19a, 19b, and 19c. A DC voltage is input from the DC power supply 2 between the pair of input terminals 13a and 13b, and the DC voltage is boosted. These two types of output voltages are output from the output terminals 19a and 19b, respectively. The output terminal 19c is a reference potential portion for those output voltages. Further, the semiconductor switch element 15 is an FET in the present embodiment.

  In the DC boost circuit 3, the primary winding 14a of the boost transformer 14 and the semiconductor switch element 15 are connected in series between a pair of input terminals 13a and 13b. The gate of the semiconductor switch element 15 (control signal input unit) is connected to the controller 7, and a pulse signal having a predetermined cycle is applied from the controller 7 to the gate of the semiconductor switch element 15. (Blocking) is controlled.

  Of the rectifying diodes 16 and 17, the rectifying diode 16 has an anode connected to one end of the secondary winding 14b of the step-up transformer 14 and a cathode smoothing to the other end of the secondary winding 14b. It is connected via a capacitor 18. Therefore, the rectifying diode 16 and the smoothing capacitor 18 are connected in series between both ends of the secondary winding 14b. One end of the smoothing capacitor 18 on the rectifying diode 16 side (one end on the high potential side) and the other end on the secondary winding 14b side are connected to the output terminals 19b and 19c, respectively.

  The anode of the rectifying diode 17 is connected to one end of the secondary winding 14c, and the cathode is connected to the output terminal 19a. The other end of the secondary winding 14c is connected to one end of the smoothing capacitor 18 on the rectifying diode 16 side.

  The output terminal 19 a to which the cathode of the rectifying diode 17 is connected is connected to the grounding part via the smoothing capacitor 20. The smoothing capacitor 20 is provided close to the rectifying diode 17.

  In the DC booster circuit 3 configured as described above, the semiconductor switch element 15 is turned ON / OFF at a predetermined cycle in a state where a DC voltage (about 12 V) is input from the DC power supply 2 between the input terminals 13a and 13b. Then, by applying a DC voltage from the DC power source 2 to the primary winding 14a of the step-up transformer 14 periodically, two types of DC voltages obtained by boosting the DC voltage input from the DC power source 2 are output. Output from terminals 19a and 19b. At this time, the ON / OFF duty of the semiconductor switch element 15 is controlled by the controller 7, and the magnitude of the DC voltage output from each of the output terminals 19 a and 19 b can be adjusted by the control. The output from the output terminal 19b mainly supplies power for lighting to the HID lamp 5, and the output from the output terminal 19a supplies power for operation to the starting circuit 6.

  In this case, in this embodiment, the maximum voltage that can be output from the output terminal 19b (maximum output voltage when the output current is 0) is about 200V. The maximum voltage that can be output from the output terminal 19a (maximum output voltage when the output current is 0) is higher than the maximum output voltage from the output terminal 19b, for example, about 950V. The number of turns of the primary winding 14a of the step-up transformer 14 and the turn ratio of each of the secondary windings 14b and 14c are such that the maximum output voltage can be generated from the output terminals 19b and 19a, respectively. Is set to

  In particular, the turn ratio between the primary winding 14a and the secondary winding 14b of the step-up transformer 14 can generate a maximum output voltage of about 200 V from the output terminal 19b, and can stabilize the HID lamp 5. The DC voltage of the DC power supply 2 and the HID so that power can be supplied to the HID lamp 5 as efficiently as possible during lighting (steady lighting) (so that the power conversion efficiency in the step-up transformer 14 is as high as possible). It is set to be approximately equal to the ratio to the generated voltage (lamp voltage) when the lamp 5 is stably lit. In this case, since the DC voltage of the DC power supply 2 (battery) varies, the turn ratio between the primary winding 14a and the secondary winding 14b is a DC power supply that can cause the discharge lamp lighting device 1 to operate normally. 2 is preferably set to be approximately equal to the ratio between the minimum guaranteed voltage of 2 and the lamp voltage when the HID lamp 5 is stably lit. For example, when the lamp voltage at the time of stable lighting of the HID lamp 5 (mercury-free HID lamp) is about 42V and the minimum guaranteed voltage of the DC power supply 2 (battery) is 10V, the primary winding 14a of the step-up transformer 14 And the secondary winding 14b are preferably set to have a winding ratio of about 1: 4. Thus, by setting the turn ratio between the primary winding 14a and the secondary winding 14b of the step-up transformer 14, the conversion efficiency of the step-up transformer 14 during continuous lighting of the HID lamp 5 can be increased. it can.

  In consideration of variations in lamp voltage during stable lighting of the mercury-free HID lamp, the lamp voltage is about 33V to 51V (42V ± 9V). Therefore, in order to make the turns ratio of the primary winding 14a and the secondary winding 14b substantially equal to the ratio between the minimum guaranteed voltage of the DC power supply 2 and the lamp voltage when the HID lamp 5 is stably lit, The winding number ratio may be set in the range of 1: 3 to 1: 5.

  Supplementally, the secondary windings 14b and 14c of the step-up transformer 14 of the DC booster circuit 3 correspond to the first secondary winding and the second secondary winding in the present invention, respectively. The rectifying diodes 16 and 17 correspond to the first rectifying diode and the second rectifying diode in the present invention, respectively, and the smoothing capacitors 18 and 20 respectively correspond to the first smoothing capacitor and the second rectifying diode in the present invention. It corresponds to the smoothing capacitor.

  The inverter circuit 4 is configured by bridging four semiconductor switch elements 4a, 4b, 4c, and 4d as in the conventional circuit of FIG. More specifically, the inverter circuit 4 is configured by connecting a series circuit of semiconductor switch elements 4a and 4b and a series circuit of semiconductor switch elements 4c and 4d in parallel between a pair of input terminals 21a and 21b. . The midpoint of the series circuit of the semiconductor switch elements 4a and 4b and the midpoint of the series circuit of the semiconductor switches 4c and 4d are connected to the pair of output terminals 22a and 22b of the inverter circuit 4, respectively. In addition, each semiconductor switch element 4a-4d is FET in this embodiment. The gates (control signal input units) of the semiconductor switch elements 4a to 4d are connected to the controller 7. By applying a pulse signal from the controller 7 to the gates, the semiconductor switch elements 4a to 4d are turned ON / OFF. (Conduction / interruption) is controlled.

  Of the input terminals 21 a and 21 b of the inverter circuit 4, the input terminal 21 a is connected to the output terminal 19 b of the DC boost circuit 3, and the input terminal 21 b is connected to the DC boost circuit 3 through the current detection resistor 12. Output terminal 19c (reference potential terminal). As a result, an output voltage (a DC voltage of about 200 V at the maximum) is input to the inverter circuit 4 from the output terminal 19 b of the DC booster circuit 3.

  In the inverter circuit 4 configured as described above, the semiconductor switch elements 4a and 4d are turned on and the semiconductor switch elements 4b and 4c are turned off, and the semiconductor switch elements 4a and 4d are turned off. And an alternating voltage having substantially the same amplitude as the direct current voltage input from the output terminal 19b of the direct current booster circuit 3 by alternately and periodically switching between the semiconductor switch elements 4b and 4c. Are output from the output terminals 22a and 22b. Further, the semiconductor switch elements 4a and 4d are turned on and the semiconductor switch elements 4b and 4c are turned off, or the semiconductor switch elements 4a and 4d are turned off and the semiconductor switch elements 4b and 4c are turned off. By continuing the state of turning on the set of the DC voltage, a DC voltage having the same polarity or opposite polarity as the DC voltage input from the output terminal 19b of the DC booster circuit 3 and substantially the same magnitude as the DC voltage is obtained. It is output from the output terminals 22a and 22b of the inverter circuit 4.

  The startup circuit 6 includes a series circuit of a charging resistor 23 and a capacitor 24, a startup transformer 25, and a breakdown element as a switching element that autonomously conducts when a voltage higher than a predetermined breakdown voltage is applied. 26.

  In this case, one end of the series circuit of the charging resistor 23 and the capacitor 24 on the capacitor 24 side is connected to the output terminal 22 b of the inverter circuit 4, and the other end on the charging resistor 23 side is connected to the output terminal 19 a of the DC booster circuit 3. It is connected to the. That is, the charging resistor 23 and the capacitor 24 are connected in series between the output terminal 19 a of the DC booster circuit 3 and the output terminal 22 b of the inverter circuit 4. Thereby, the capacitor 24 is output from the output terminal 19a of the DC booster circuit 3 in a state where the set of the semiconductor switch elements 4a and 4d of the inverter circuit 4 is turned on and the set of the semiconductor switch elements 4b and 4c is turned off. It is charged via the charging resistor 23 by a direct current voltage (about 950 V).

  Further, the primary winding 25 a of the starting transformer 25 and the breakdown element 26 are connected in series between both ends of the capacitor 24. In the present embodiment, a gas-filled spark gap element having a breakdown voltage (conduction voltage) lower than 1000 V, for example, about 800 V, is used as the breakdown element 26.

  Further, the secondary winding 25 b of the starting transformer 25 is connected in series with the HID lamp 5 between the output terminals 22 a and 22 b of the inverter circuit 4.

  In the startup circuit 6 configured as described above, when the capacitor 24 is charged to about 800 V, the breakdown element 26 is turned on, and the charged charge of the capacitor 24 instantaneously causes the primary winding 25 a of the startup transformer 25. Flowing. In response to this, a starting high-pressure pulse is generated in the secondary winding 25 b of the starting transformer 25, and this is applied to the HID lamp 5. In this case, the number of turns of the primary winding 25a of the starting transformer 25 and the turn ratio of the secondary winding 25b are set so that the peak value of the starting high-voltage pulse is about 25 kV. Yes.

  In the present embodiment, the starting transformer 25 is caused by the fact that the current of the primary winding 25a stops flowing immediately after the current instantaneously flows to the primary winding 25a due to the conduction of the breakdown element 26. The back electromotive force generated in this way is used so that the width per pulse of the starting high-voltage pulse becomes larger than that of the prior art. That is, in this embodiment, a forward high-voltage pulse component (excited to the secondary winding 25b due to instantaneous current flowing from the capacitor 24 to the primary winding 25a when the breakdown element 26 is turned on) ( Hereinafter, the first high-voltage pulse component) and a high-pressure pulse component in the reverse direction (hereinafter, referred to as a first high-voltage pulse component) generated by the reverse starting force in the secondary winding 25b due to the fact that current does not flow in the primary winding 25a immediately thereafter Of the second high-voltage pulse component) is excited on the secondary winding 25b as a starting high-voltage pulse. Since the first high-pressure pulse component and the second high-pressure pulse component are damped, the waveform of the starting high-pressure pulse is also a damped vibration waveform. In this case, the first high-voltage pulse component and the second high-voltage pulse component (specifically, the same-polarity portions of the waveforms of the high-voltage pulse components) overlap each other with a slight phase shift, thereby starting the high-voltage pulse for activation. The connectivity of the winding 25a or 25b of the starting transformer 25 is adjusted so that the pulse portion of the damped oscillation waveform is formed. Specifically, in the present embodiment, the starting transformer 25 is set so that the inductance value of the primary winding 25a of the starting transformer 25 is three times or more the leakage inductance value of the primary winding 25a. Configured. In general, the leakage inductance of the primary winding 25a tends to decrease as the number of turns of the primary winding 25a increases.

  FIG. 2 shows an example of the waveform of the starting high-voltage pulse generated in the secondary winding 25b of the starting transformer 25 configured as described above. As shown in the figure, the waveform of the starting high-voltage pulse in the present embodiment is a damped oscillation waveform in which the same polarity portions of the first high-voltage pulse component V1 and the second high-voltage pulse component V2 that overlap with each other are shifted in phase. It becomes. As a result, the width W (the width corresponding to a half period of the waveform) of the waveform of the start high voltage pulse formed by synthesizing these high voltage pulse components is larger than the width of each high voltage pulse component V1, V2. Thus, it is larger than the starting high-pressure pulse in the conventional discharge lamp lighting device shown in FIG.

  According to various experiments and examinations by the inventor of the present application, when the width of the starting high-pressure pulse applied to the HID lamp 5 is wider, the discharge of the HID lamp 5 can be stably excited. Discharge / lighting can be started smoothly. This effect is particularly prominent when the voltage applied from the DC booster circuit 3 to the HID lamp 5 is relatively low before the discharge / lighting of the HID lamp 5 is started. For this reason, in the present embodiment, as described above, the primary winding 25a of the starting transformer 25 is arranged so that the same polarity portions of the first high-voltage pulse component V1 and the second high-voltage pulse component V2 are shifted in phase. In order to increase the width of the start-up high-pressure pulse, the connectivity was adjusted.

  When the value of the inductance of the primary winding 25a is set to about twice the value of the leakage inductance of the primary winding 25a, the phase shift between the first high-voltage pulse component and the second high-voltage pulse component is caused. When the applied high voltage before starting the lighting of the HID lamp 5 is about 200 V, the discharge and lighting of the HID lamp 5 cannot be started smoothly when the width of the starting high-voltage pulse is not sufficiently wide. There is a case. In this embodiment, in order to widen the width of the starting high-voltage pulse, the connectivity of the primary winding 25a of the starting transformer 25 is adjusted, but the connectivity of the secondary winding 25b or both windings is adjusted. The connectivity of 25a and 25b may be adjusted.

  Supplementally, the capacitor 24 of the starting circuit 6 corresponds to the starting capacitor in the present invention.

  The first starting auxiliary circuit 8 includes a capacitor 27, a charging resistor 28, a discharging resistor 29, and a discharging diode 30. More specifically, the first startup auxiliary circuit 8 connects a series circuit formed by connecting a discharging resistor 30 and a discharging diode 30 in series and a charging resistor 28 in parallel, and connects one end of the parallel circuit. The capacitor 27 is connected in series. In this case, the discharging diode 30 prevents the current from flowing through the capacitor 27 via the discharging resistor 29 when the capacitor 27 is charged, and the current flows via the discharging resistor 29 when the capacitor 27 is discharged. It is provided in an orientation that allows it to flow. In this embodiment, the anode of the discharge diode 30 is connected to the capacitor 27, and the cathode is connected to the discharge resistor 29. Further, the resistance value of the charging resistor 28 is greater than the resistance value of the discharging resistor 29 so that the current during discharging of the capacitor 27 substantially flows only through the series circuit of the discharging resistor 29 and the discharging diode 30. Have a large resistance value.

  The second starting auxiliary circuit 9 is configured by connecting a capacitor 31, a charging resistor 32, a discharging resistor 33, and a discharging diode 34 in the same manner as the first starting auxiliary circuit 8. Also in the second starting auxiliary circuit 9, the resistance of the charging resistor 32 is such that the current during discharging of the capacitor 31 flows substantially only through the series circuit of the discharging resistor 33 and the discharging diode 34. The value has a resistance value larger than the resistance value of the discharging resistor 33.

  The first start-up auxiliary circuit 8 and the second start-up auxiliary circuit 9 are interposed between the DC booster circuit 3 and the inverter circuit 4. More specifically, one end of each of the first start-up auxiliary circuit 8 and the second start-up auxiliary circuit 9 on the side of the capacitors 27 and 31 is connected to the input terminal 21b of the inverter circuit 4 and via the current detection resistor 12. Are connected to an output terminal 19c (reference potential terminal) of the DC booster circuit 3. The other ends of the first start-up auxiliary circuit 8 and the second start-up auxiliary circuit 9 are connected to the output terminal 19b of the DC boost circuit 3 and the input terminal 21a of the inverter circuit 4. Therefore, a voltage equal to the voltage input from the DC booster circuit 3 to the inverter circuit 4 is applied to the first startup auxiliary circuit 8 and the second startup auxiliary circuit 9.

  In the first startup auxiliary circuit 8 configured as described above, the capacitor 27 is charged from the output terminal 19b of the DC booster circuit 3 through the charging path having the charging resistor 28, and the capacitor 27 is charged. The electric charge is discharged through a discharge path having the discharge diode 30 and the discharge resistor 29. For this reason, a charging path and a discharging path for the capacitor 27 are provided separately. And the time constant of each of those charging paths and discharging paths is set separately. The same applies to the second startup auxiliary circuit 9.

  In this case, the time constant of the discharge path of the first starting auxiliary circuit 8, that is, the capacitance value of the capacitor 27 and the resistance value of the discharging resistor 29 (more precisely, the resistance of the series circuit of the discharging resistor 29 and the discharging diode 30) Value) is the time constant of the discharge path of the second auxiliary start circuit 9, that is, the capacitance value of the capacitor 31 and the resistance value of the discharge resistor 33 (more precisely, the discharge resistor 33 and the discharge diode 34). Their capacitance value and resistance value are set so as to be smaller than the product of the resistance value of the series circuit). That is, the discharge of the capacitor 27 of the first start-up auxiliary circuit 8 is performed earlier than the discharge of the capacitor 31 of the second start-up auxiliary circuit 9.

  The voltage detecting voltage dividing resistors 10 and 11 are connected in series between the output terminals 19b and 19c of the DC boosting circuit 3, and the voltage generated by the voltage dividing resistor 11 on the output terminal 19c side (this is the DC voltage boosting circuit). The output voltage is proportional to the output voltage between the output terminals 19 b and 19 c of the circuit 3) and is output to the controller 7 as a detection signal indicating the generated voltage (lamp voltage) of the HID lamp 5. The current detection resistor 12 outputs the generated voltage to the controller 7 as a detection signal indicating the current (lamp current) flowing through the HID lamp 5.

  The above is the circuit configuration of the discharge lamp lighting device 1 of the present embodiment.

  Here, design guidelines such as circuit constants of the discharge lamp lighting device 1 of the present embodiment will be described. The smoothing capacitor 18 of the DC booster circuit 3 is for smoothing the output voltage between the output terminals 19b and 19c of the DC booster circuit 3. After the HID lamp 5 starts discharging and lighting, the HID lamp 5 In order to stably light the lamp 5, a certain amount of ripple component (high frequency component) is required for the lamp voltage and lamp current. For this reason, the capacitance value of the smoothing capacitor 18 of the DC boost circuit 3 is set so that the lamp current having such a ripple component can be passed from the DC boost circuit 3 to the HID lamp 5 via the inverter circuit 4. Has been. The capacitance value may be, for example, approximately the same as the capacitance value of the smoothing capacitor 113 of the DC booster circuit 101 of the conventional discharge lamp lighting device described above (for example, 0.2 μF to 0.8 μF). However, as described above, the mercury-free HID lamp which is the HID lamp 5 in the present embodiment has a lamp current required for stable lighting larger than that of the mercury-filled HID lamp. Therefore, the lamp current includes a certain ripple component. The capacitance value of the smoothing capacitor 18 that may be used may be a larger value (for example, 1 μF to 2 μF) than when a mercury-filled HID lamp is used. Note that instability of lighting of the HID lamp due to too little ripple component is likely to occur in a state where the HID lamp has deteriorated, and therefore, the capacitance value of the smoothing capacitor 18 has been deteriorated to some extent. It is desirable to check using an HID lamp.

  The first start-up auxiliary circuit 8 cooperates with the smoothing capacitor 18 of the DC booster circuit 3 as will be described later in order to cause an inrush current to flow through the HID lamp 5 at the start of discharge / lighting of the HID lamp 5. The purpose is to supply from the capacitor 27 to the HID lamp 5. Further, as will be described later, the second start-up auxiliary circuit 9 starts from the capacitor 31 to the HID lamp 5 so as to prevent an excessive drop of the lamp current immediately after the inrush current flows through the HID lamp 5 (to maintain the lamp current). The purpose is to pass a current through. Accordingly, the capacitance values of the capacitors 27 and 31 of the start assist circuits 8 and 9 are set so as to satisfy the respective purposes. For example, the capacitance value of the capacitor 27 is set to about 3.3 to 4.7 μF, and the capacitance value of the capacitor 31 is set to about 4.7 to 6.8 μF.

  In this case, in this embodiment, the maximum output voltage that can be output from the output terminal 19b of the DC boost circuit 3 (the maximum voltage that can be applied from the DC boost circuit 3 to the HID lamp 5 via the inverter circuit 4) is as described above. About 200 V, which is about half of the maximum output voltage (about 400 V) of the DC booster circuit 101 of the conventional discharge lamp lighting device. Therefore, when the capacitance value of the smoothing capacitor 18 of the DC booster circuit 101 is the same as that of the smoothing capacitor 113 of the DC booster circuit 101 of the conventional discharge lamp lighting device, immediately before the discharge / lighting of the HID lamp 5 starts. The electrical energy that can be charged in the smoothing capacitor 18 is ¼ that of the conventional one. Therefore, when the capacitance value of the smoothing capacitor 18 of the DC boost circuit 101 is the same as that of the smoothing capacitor 113 of the DC boost circuit 101 of the conventional discharge lamp lighting device, the capacitance value of the capacitor 27 of the first startup auxiliary circuit 8 is The capacitance value of the smoothing capacitor 18 is preferably set to 4 times or more.

  Further, the capacitance value of the capacitor 31 of the second startup auxiliary circuit 9 may be approximately the same as the capacitance value of the capacitor 27 of the first startup auxiliary circuit 8, for example. However, since the capacitor 31 of the second start-up auxiliary circuit 9 aims at sustaining the lamp current immediately after the inrush current flows to the HID lamp 5, its capacitance value is the capacity of the capacitor 27 of the first start-up auxiliary circuit 8. It may be larger than the value.

  If the resistance value of the charging resistor 28 of the first starting auxiliary circuit 8 and the charging resistor 32 of the second starting auxiliary circuit 9 are too small, the ripple component is changed to the capacitors 27 and 31 of the starting auxiliary circuits 8 and 9. Will be absorbed. Therefore, in this embodiment, the resistance values of the charging resistors 28 and 32 are set to values of about several hundred Ω to several kΩ. Further, the resistance value of the discharging resistor 29 of the first starting auxiliary circuit 8 is such that an inrush current is supplied from the capacitor 27 to the HID lamp 5 almost simultaneously with the smoothing capacitor 18 of the DC booster circuit 3 when the HID lamp 5 is started. In addition, a sufficiently small resistance value is set. The resistance value is, for example, several Ω to several tens Ω. Note that the discharging resistor 29 of the first startup auxiliary circuit 8 may be omitted. In other words, only the discharge diode 30 may be provided in the discharge path of the first startup auxiliary circuit 8.

  Further, as described above, the resistance value of the discharge resistor 33 of the second start-up auxiliary circuit 9 is equal to the time constant of the discharge path of the second start-up auxiliary circuit 8 and the time constant of the discharge path of the first start-up auxiliary circuit 8. Is set to be larger. The resistance value is, for example, several tens Ω to several hundreds Ω.

  Since the discharge diodes 30 and 34 are provided in the discharge paths of the start-up auxiliary circuits 8 and 9, the resistance values of the discharge resistors 29 and 33 do not affect the ripple component.

  In this embodiment, the maximum value of the voltage that can be applied from the DC booster circuit 3 to the HID lamp 5 via the inverter circuit 4 is about 200 V as described above, and is about half that of the conventional discharge lamp lighting device described above. It was. For this reason, the breakdown voltage of each of the semiconductor switch elements 4a to 4d of the inverter circuit 4 can be lowered as compared with the prior art, and as a result, the ON resistance (resistance during conduction) of each of the semiconductor switch elements 4a to 4d is made smaller than the conventional. be able to. Therefore, in the present embodiment, as the semiconductor switch elements 4a to 4d, those whose ON resistance is about 1/3 of the conventional resistance value (for example, about 0.25Ω) are used.

  In addition, when a gas-filled spark gap element that conducts at a breakdown voltage of about 800 V as described above is used as the breakdown element 26 of the startup circuit 6, the startup circuit 6 generates a startup high-voltage pulse. In addition, the voltage induced in the primary winding 25a of the starting transformer 25 is made higher than the conventional voltage. As a result, the number of turns of the secondary winding 25b of the starting transformer 25 required for generating a starting high-voltage pulse having a peak value of about 25 kV in the secondary winding 25b of the starting transformer 25 is reduced as compared with the conventional case. I did it. In addition, in this embodiment, by using a tape-shaped rectangular wire as the secondary winding 25b of the starting transformer 25, the resistance value of the secondary winding 25b is achieved while reducing the size of the starting transformer 25. (DC resistance value) was made as small as possible. For this reason, the resistance value (DC resistance value) of the secondary winding 25b of the starting transformer 25 in this embodiment is 1Ω or less, and the secondary winding of the starting transformer 119 of the above-described conventional discharge lamp lighting device is It is set to 1/3 or less of the resistance value.

  Further, as described above, since the breakdown element 26 having a breakdown voltage of about 800V is used, a high voltage of about 950V at the maximum from the output terminal 19a of the DC booster circuit 3 is expected in consideration of variations in the breakdown voltage. The step-up transformer 14 of the DC step-up circuit 3 is configured so that the direct current voltage is output. In this case, one end of the secondary winding 14c of the step-up transformer 14 is connected to one end (one end on the high potential side) of the smoothing capacitor 18, so that the counter electromotive force of the secondary winding 14c is turned off when the rectifying diode 17 is turned off. Thus, the voltage acting on the rectifying diode 17 is set to be 1000 V or less. Thereby, the required withstand voltage of the rectifying diode 17 is suppressed to 1000 V or less, and a small rectifying diode 17 can be used.

  Further, in this case, since a high voltage of about 950 V is supplied from the output terminal 19a of the DC booster circuit 3 to the starting circuit 6, a large amount of high frequency noise is radiated, which may affect the operation of the inverter circuit 4. If the DC voltage output from the output terminal 19a of the DC booster circuit 3 has too much ripple component, the charging efficiency of the capacitor 24 of the starter circuit 6 is reduced. For this reason, in the present embodiment, the output terminal 19a of the DC booster circuit 3 is connected to the grounding part via the smoothing capacitor 20 in the vicinity of the rectifying diode 17, so that the output ripple from the output terminal 19a is reduced to some extent. I made it. In this case, the capacitance value of the smoothing capacitor 20 may be as small as about 1000 pF, for example.

  The capacitance value of the capacitor 24 of the starting circuit 6 is set to, for example, about 100 nF in order to generate a starting high-voltage pulse having a peak value of about 25 kV in the secondary winding 25b of the starting transformer 25. Further, the resistance value of the charging resistor 23 of the starting circuit 6, and the time constant of the charging path of the capacitor 24, the charging of the capacitor 24 after the charging of the capacitors 27 and 31 of each of the starting auxiliary circuits 8 and 9 is completed. The voltage is set so as to reach a breakdown voltage (about 800 V) of the breakdown switch element 26.

  Next, the operation of the discharge lamp lighting device 1 of the present embodiment will be described with reference to FIGS. 3 (a), 3 (b) and FIG. 3A and 3B are timing charts illustrating the time-dependent changes in the generated voltage (lamp voltage) and current (lamp current) of the HID lamp 5 when the HID lamp 5 is lit, and FIG. It is a graph which shows the example of a setting of the target value of the lamp electric current or lamp electric power at the time of AC lighting of the HID lamp.

  When a DC power source 2 is connected between the input terminals 13a and 13b of the DC booster circuit 3 and a DC voltage (about 12V) is input from the DC power source 2 to the DC booster circuit 3, the discharge lamp lighting device 1 is as follows. Operate.

  First, the controller 7 controls the set of semiconductor switch elements 4a and 4d of the inverter circuit 4 to an ON state and controls the set of semiconductor switch elements 4b and 4c to an OFF state. At the same time, the controller 7 PWM-controls the semiconductor switch element 15 of the DC booster circuit 3 to boost the DC voltage input from the DC power supply 2 by the DC booster circuit 3 (time t1 in FIG. 3A). ~ T2).

  In this case, the output voltage from the output terminal 19b of the DC booster circuit 3 is increased to a voltage of about 200V as the maximum voltage, and this maximum output voltage is passed from the output terminal 19b of the DC booster circuit 3 via the inverter circuit 4. Applied to the HID lamp 5. Therefore, the lamp voltage of the HID lamp 5 rises to a voltage of about 200 V during the period from time t1 to time t2 in FIG.

  Further, during this period, the output voltage from the output terminal 19b of the DC booster circuit 3 causes the capacitors 27 and 31 of the respective start-up auxiliary circuits 8 and 9 to pass through the charging resistors 28 and 32 and the maximum value of the output voltage ( The battery is charged to a voltage almost equal to about 200V).

  Further, during this period, the output voltage from the output terminal 19 a of the DC booster circuit 3 is increased to a voltage of about 950 V, and the capacitor 24 of the starting circuit 6 is charged via the charging resistor 23 by the voltage. In this case, after the charging of the capacitors 27 and 31 of the auxiliary start circuits 8 and 9 is completed, the charging voltage of the capacitor 24 rises to the breakdown voltage (about 800 V) of the breakdown switch element 26.

  When the charging voltage of the capacitor 24 of the starting circuit 6 reaches the breakdown voltage of the breakdown switching element 26, the breakdown switching element 26 is turned on, and the charging charge of the capacitor 24 is instantaneously applied to the starting transformer 25a. Discharge occurs through the primary winding 25a. At this time, a starting high-voltage pulse having a peak value of about 25 kV (a high-pressure pulse having a waveform as illustrated in FIG. 2) is excited in the secondary winding 25b of the starting transformer 25. The voltage is applied to the HID lamp 5 by being superimposed on the DC voltage (about 200 V) applied to the HID lamp 5 from the booster circuit 3 through the inverter circuit 4 (time t2 in FIGS. 3A and 3B).

  Thereby, discharge / lighting of the HID lamp 5 is started. At the start of discharge and lighting of the HID lamp 5, an inrush current at the start of discharge of the HID lamp 5 is supplied to the HID lamp 5 from the smoothing capacitor 18 of the DC booster circuit 3 through the inverter circuit 4. At the same time, an inrush current is supplied from the capacitor 27 of the first auxiliary start circuit 8 to the HID lamp 5 through the inverter circuit 4 (period from time t2 to time t3 in FIG. 3B).

  That is, since the discharge resistor 29 in the discharge path of the capacitor 27 of the first start-up auxiliary circuit 8 is set to a resistance value sufficiently close to 0 (for example, several Ω to several tens Ω), the discharge of the HID lamp 5 is started. At the time (immediately after the application of the starting high voltage pulse), the charge of the capacitor 27 of the first starting auxiliary circuit 8 is discharged to the HID lamp 5 through the inverter circuit 4 almost simultaneously with the smoothing capacitor 18 of the DC boosting circuit 3. To do. Thereby, a sufficient inrush current is supplied to the HID lamp 5, and the discharge of the HID lamp 5 can be started without any trouble.

  Here, as described above, since a certain amount of ripple component is necessary for the lamp current of the HID lamp 5, the capacitance value of the smoothing capacitor 18 of the DC boost circuit 3 cannot be increased too much. In this embodiment, the maximum voltage (about 200 V) applied to the HID lamp 5 from the DC booster circuit 3 via the inverter circuit 4 before the lighting of the HID lamp 5 is reduced to about half that of the conventional discharge lamp lighting device. Yes. For this reason, it is difficult to sufficiently supply the HID lamp 5 with the inrush current required at the start of discharge in the smoothing capacitor 18 having a capacitance value that can include a certain amount of ripple in the lamp current. For example, if the first start auxiliary circuit 8 is omitted, the inrush current to the HID lamp 5 cannot be sufficiently increased as shown by the broken line a in FIG. However, in the present embodiment, the shortage of the inrush current from the smoothing capacitor 18 of the DC booster circuit 3 to the HID lamp 5 is compensated by the capacitor 27 of the first startup auxiliary circuit 8. Thereby, the inrush current required for the start of the discharge and lighting can be supplied to the HID lamp 5.

  In the present embodiment, as described above, since the pulse width W of the starting high voltage pulse of the starting circuit 6 is relatively large, the DC boosting circuit 3 changes to the HID lamp 5 when the HID lamp 5 is started. Even if the applied voltage is a low voltage of about 200 V, the discharge of the HID lamp 5 can be started stably.

  Since the inrush current flows through the HID lamp 5 as described above, the smoothing capacitor 18 of the DC booster circuit 3 and the capacitor 27 of the first startup auxiliary circuit 8 are rapidly discharged, so that the lamp current is the discharge of the HID lamp 5. It decreases rapidly from the peak value at the start. In this case, if the second start-up auxiliary circuit 9 is not provided, the lamp current may drop excessively and the discharge / lighting of the HID lamp 5 may stop as shown by the broken line b in FIG. . However, in the present embodiment, the second start-up auxiliary circuit 9 prevents the lamp current from dropping.

  That is, the capacitor 31 of the second startup auxiliary circuit 8 starts discharging through the discharge resistor 33 from the start of discharge / lighting of the HID lamp 5, but the discharge is caused by the capacitor of the first startup auxiliary circuit 8. It is performed more slowly than 27. For this reason, a substantial current is supplied from the second starting auxiliary circuit 9 to the HID lamp 5 immediately after the inrush current is supplied to the HID lamp 5 (period from time t3 to t4 in FIG. 3B). ). As a result, it is possible to prevent the lamp current from dropping excessively and to maintain an appropriate lamp current for continuing the discharge and lighting of the HID lamp 5.

  In the present embodiment, as described above, the width of the starting high-voltage pulse is widened and the first start-up auxiliary circuit 8 and the second start-up auxiliary circuit 9 are provided, so that the DC boosting can be performed before the HID lamp 5 starts lighting. Discharging / lighting of the HID lamp 5 can be started smoothly while the voltage (about 200 V) applied from the circuit 3 to the HID lamp 5 is significantly lower than the conventional one.

  Immediately after the start (cold start) of the HID lamp 104 in a state where the HID lamp 5 is cooled, the lamp voltage generated in the HID lamp 104 is about 25V. After application, the voltage decreases (period from time t2 to time t6 in FIG. 3A).

  On the other hand, in order to stabilize the discharge immediately after the activation of the HID lamp 5, the controller 7 determines the period from the start of the activation of the HID lamp 5 until a predetermined time elapses (time t2 in FIGS. 3A and 3B). To a discharge stabilization period from t6 to t6), in the same manner as in the past, for a predetermined time (for example, about 10 to 20 ms) sufficiently longer than the cycle of the AC lighting frequency (for example, 400 Hz) during steady lighting of the HID lamp 5, The inverter circuit 4 is controlled so that positive and negative direct currents flow sequentially through the HID lamp 5. That is, in the discharge stabilization period, in the period from time t2 to t5 in FIGS. 3A and 3B, a positive lamp current is supplied to the HID lamp 5, and in the subsequent period from time t5 to t6. The semiconductor switch elements 4a to 4d of the inverter circuit 4 are controlled in the same manner as the conventional discharge lamp lighting device described above so that a negative lamp current flows through the HID lamp 104. Further, during these periods, as in the conventional case, the lamp current or the supply to the HID lamp 5 according to the detection signal of the lamp voltage input to the controller 7 via the voltage detecting voltage dividing resistors 10 and 11. A power target value is determined. The lamp current detected via the current detection resistor 12 or the lamp power (power supplied to the HID lamp 5) grasped from the detected value of the lamp current and the detected value of the lamp voltage is the target value. So that the output of the DC booster circuit 3 is feedback-controlled by the controller 7 via the semiconductor switch element 15.

  Further, after the end of the discharge stabilization period (period after time t6 in FIGS. 3 (a) and 3 (b)), the AC at a predetermined frequency (for example, 400 Hz) of the HID lamp 5 is the same as the conventional one. Lights up.

  That is, alternating ON / OFF of the group of semiconductor switch elements 4a and 4d and the group of semiconductor switch elements 4b and 4c of the inverter circuit 4 is controlled by the controller 7 at a frequency of about 400 Hz. Thereby, AC lighting of the HID lamp 104 is performed. Further, the target value of the lamp current or lamp power in this AC lighting is set according to the lamp voltage (the output voltage of the DC booster circuit 3) detected through the voltage detection voltage dividing resistors 10 and 11, and The DC booster circuit 3 is configured so that the lamp current detected through the current detection resistor 12 or the lamp power obtained from the detected value of the lamp current and the detected value of the lamp voltage becomes the target value. The ON / OFF duty of the semiconductor switch element 15 is feedback controlled by the controller 7.

  In this case, since the HID lamp 5 is a mercury-free HID lamp in this embodiment, the target value of the lamp current or lamp power in AC lighting is the lamp voltage (the output voltage of the DC booster circuit 3) as illustrated in FIG. ) Is set according to the detected value.

  By controlling the lamp current or lamp power during AC lighting of the HID lamp 5 in this way, the lamp voltage gradually increases as shown in FIG. 3A, and finally stable at a voltage of about 42V. To do. Further, as shown in FIG. 3B, the lamp current gradually decreases and finally becomes stable at a current of about 0.8 A.

  As described above, in the present embodiment, the width of the starting high voltage pulse is widened, and the first starting auxiliary circuit 8 and the second starting auxiliary circuit 9 are provided, so that the HID lamp 5 can be turned on before the lighting starts. Smooth discharge and lighting of the HID lamp 5 while the voltage applied to the HID lamp 5 (maximum output voltage from the output terminal 19b of the DC booster circuit 3) is about 200 V, which is significantly lower than that of the conventional discharge lamp lighting device. Can start.

  Further, as the maximum output voltage from the output terminal 19b of the DC booster circuit 3 is set to a low voltage of about 200V, the required breakdown voltage of each of the semiconductor switch elements 4a to 4d of the inverter circuit 4 is lowered, and the ON resistance thereof is reduced. It is reduced to 1/3 or less of the conventional discharge lamp lighting device. In addition, a rectangular wire is used as the secondary winding 25b of the starter transformer 25 connected in series to the HID lamp 5, and the number of turns of the secondary winding 25b is reduced to reduce the secondary winding. The resistance value (DC resistance value) of 25b is reduced to 1/3 or less of the conventional discharge lamp lighting device. Further, the maximum output voltage from the output terminal 19b of the DC booster circuit 3 is set to about half of the maximum output voltage of the DC booster circuit 101 of the conventional discharge lamp lighting device, so that 2 of the step-up transformer 14 of the DC booster circuit 3 is obtained. The number of turns of the secondary winding 14b can be significantly reduced from the number of turns of the secondary winding of the step-up transformer 111 of the conventional discharge lamp lighting device. As a result, the resistance value (DC resistance value) of the secondary winding 14b of the step-up transformer 14 of the DC boost circuit 3 can be significantly reduced as compared with the conventional one. For example, when the primary winding 14a of the step-up transformer 14 is the same as the conventional one, the resistance value of the secondary winding 14b of the step-up transformer 14 in the present embodiment is about 50 mΩ, and the step-up transformer 111 of the conventional discharge lamp lighting device. The resistance value of the secondary winding (about 300 mΩ) can be reduced to 1/6.

  As described above, the resistance value of the circuit components (circuit components through which the lamp current flows) of the discharge lamp lighting device 1 can be reduced, so that the mercury-free HID in which the lamp current during stable lighting is larger than that of the mercury-filled HID lamp. Even if the lamp is used as a discharge lamp, the generation of Joule heat in the secondary winding 25b of the DC booster circuit 3, the inverter circuit 4, and the starting transformer 25 can be reduced. In addition, in the present embodiment, the winding ratio of the primary winding 14a and the secondary winding 14b of the step-up transformer 14 of the DC boosting circuit 3 is set as described above, so that the HID lamp 5 can be continuously formed. The conversion efficiency of the step-up transformer 14 during lighting is increased. As a result, in the discharge lamp lighting device 1 of the present embodiment, heat generation can be reduced and circuit efficiency can be increased as compared with the conventional discharge lamp lighting device. For example, in the conventional discharge lamp lighting device, the circuit efficiency when the mercury-free HID lamp is continuously lit is about 75%, but in the discharge lamp lighting device 1 of the present embodiment, it is 82%. High circuit efficiency was achieved. Further, regarding the heat generation, in the conventional discharge lamp lighting device, the temperature of the outer case increases by about 50 deg. However, in the discharge lamp lighting device 1 of the present embodiment, the temperature increase of the outer case may be limited to about 25 deg. did it.

  Further, the voltage detection voltage dividing resistor 10, while the HID lamp 5 is lit, can be reduced by reducing the ON resistance of the semiconductor switch elements 4 a to 4 d of the inverter circuit 4 and the resistance value of the secondary winding 25 b of the starting transformer 25. The difference between the lamp voltage detected via 11 and the actual lamp voltage can be reduced, and the detection accuracy of the lamp voltage can be increased. As a result, even if a mercury-free HID lamp whose variation in lamp voltage during AC lighting is smaller than that of a mercury-filled HID lamp is used as a discharge lamp, the lamp current of the HID lamp 5 and the lamp during H.C. The electric power can be accurately controlled to an optimum target value according to the detected value of the lamp voltage, and appropriate lighting control of the HID lamp 5 can be stably performed.

  Further, by reducing the maximum output voltage from the DC booster circuit 3 to the HID lamp 5, each of the rectifying diode 16, the smoothing capacitor 18, and the inverter circuit 4 on the secondary winding 14b side of the booster transformer 14 of the DC booster circuit 3 is achieved. Since the breakdown voltage of the semiconductor switch elements 4a to 4d and the like can be lowered, it is possible to reduce the size and cost of those circuit components. Further, even in the rectifying diode 17 of the DC booster circuit 3 that outputs a high voltage to the starter circuit 6, the required withstand voltage can be kept below 1000V. Therefore, the rectifying diode 17 can be reduced in size and cost. Can be achieved. As a result, the discharge lamp lighting device 1 of this embodiment can be made small and low cost.

  In the embodiment described above, the case where a mercury-free HID lamp is used as the discharge lamp has been described as an example. However, a mercury-filled HID lamp may be used. Even in this case, the maximum output voltage from the DC booster circuit 3 to the HID lamp can be reduced to a low voltage of about 200 V, and the HID lamp can be started smoothly and the circuit efficiency can be improved as compared with the conventional discharge lamp lighting device. In addition, the heat generation can be reduced as compared with the conventional discharge lamp lighting device.

  In the above embodiment, a gas-filled spark gap element is used as the breakdown element 26. However, a semiconductor bidirectional switch may be used.

  In the above-described embodiment, the secondary winding 14c and the rectifying diode 17 are added to the DC booster circuit 3 to supply the high voltage of the capacitor 24 of the starting circuit 6. However, for example, the breakdown element A switching element that conducts at about 200 V may be used as 26, and a voltage that makes the breakdown element conductive may be supplied from the DC booster circuit 3 to the capacitor 24 of the starting circuit 5 via the inverter circuit 4. In this case, the secondary winding 14c, the rectifying diode 17 and the smoothing capacitor 20 of the DC booster circuit 3 are unnecessary. In this case, by increasing the ratio of the number of turns of the secondary winding 25b to the number of turns of the primary winding 25a of the starting transformer 25, a peak value of about 25 kV is applied to the secondary winding 25b. It is also possible to generate a starting high-pressure pulse.

  In the above embodiment, one end of the secondary winding 14c of the DC booster circuit 3 is connected to one end on the high potential side of the smoothing capacitor 18. However, one end of the secondary winding 14c is connected to the ground portion or the smoothing capacitor. 18 may be connected to one end on the low potential side (reference potential terminal 19c) or may be connected to one end on the rectifier diode 16 side of the secondary winding 14b. However, in this case, the required withstand voltage of the rectifying diode 17 is larger than that in the above embodiment.

  In the above embodiment, since the maximum output voltage applied from the DC booster circuit 3 to the HID lamp 5 is significantly lower than that in the prior art, both the first start-up auxiliary circuit 8 and the second start-up auxiliary circuit 9 are provided. A sufficient current at the start of discharge of the HID lamp 5 is ensured. However, when the maximum output voltage applied to the HID lamp 5 of the DC booster circuit 3 is made higher than that of the present embodiment (however, in the prior art) For example, the capacitance value of the smoothing capacitor 18 of the DC booster circuit 3 is made as large as possible within a range in which the ripple component is not excessively reduced, so that the first start-up auxiliary circuit 8 is reduced. It is also possible to omit.

The figure which shows the circuit structure of the discharge lamp lighting device of one Embodiment of this invention. The figure which illustrates the waveform of the high voltage | pressure pulse for starting excited by the secondary winding of the starting transformer of the starting circuit with which the discharge lamp lighting device of FIG. 1 was equipped. FIGS. 3A and 3B are timing charts illustrating changes over time in the generated voltage and current of the HID lamp (discharge lamp) that is lit by the discharge lamp lighting device of FIG. The graph which shows the example of a setting of the target value of the electric current or electric power at the time of the alternating current lighting of the HID lamp by the discharge lamp lighting device of FIG. The figure which shows the example of the circuit structure of the conventional discharge lamp lighting device. FIGS. 6A and 6B are timing charts illustrating changes over time in the generated voltage and current of the HID lamp (discharge lamp) that is lit by the discharge lamp lighting device of FIG. The figure which illustrates the waveform of the high voltage | pressure pulse for starting excited by the secondary winding of the starting transformer of the starting circuit with which the discharge lamp lighting device of FIG. 5 was equipped. The graph which shows the example of a setting of the target value of the electric current or electric power at the time of the alternating current lighting of the HID lamp by the discharge lamp lighting device of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Discharge lamp lighting device, 2 ... DC power supply, 3 ... DC booster circuit, 4 ... Inverter circuit, 5 ... Discharge lamp (HID lamp), 6 ... Start-up circuit, 14 ... Boost transformer, 14a ... Primary winding of boost transformer 14b, a first secondary winding of the step-up transformer, 14c, a second secondary winding of the step-up transformer, 16 ... a first rectifying diode, 17 ... a second rectifying diode, 18 ... first 20 ... second smoothing capacitor, 24 ... starting capacitor, 25 ... starting transformer, 25a ... primary winding of starting transformer, 25b ... secondary winding of starting transformer, 26 ... Breakdown element.

Claims (4)

A DC voltage input from a DC power source is boosted, and the boosted output voltage is input to the discharge lamp via an inverter circuit, and power is supplied from the DC voltage booster circuit. A starting circuit for applying a starting high-pressure pulse for starting lighting to the discharge lamp, and at the start of lighting of the discharge lamp, a DC voltage of a predetermined value is supplied from the DC boosting circuit via an inverter circuit to the discharge lamp. In the discharge lamp lighting device for starting the lighting of the discharge lamp by applying a high-pressure pulse for starting from the starting circuit to the discharge lamp in the state applied to the discharge lamp,
The starter circuit includes a starter transformer having a secondary winding connected in series with the discharge lamp between a pair of output terminals of the inverter circuit, and power from the DC booster circuit before the discharge lamp starts lighting. A start-up capacitor to be charged by being supplied and connected in series with the primary winding of the start-up transformer between both ends of the start-up capacitor, and the charge voltage of the start-up capacitor is equal to or higher than a predetermined breakdown voltage A breakdown element that autonomously conducts when the breakdown element is turned on, and the charge of the activation capacitor is instantaneously discharged through the primary winding of the activation transformer by the conduction of the breakdown element, A circuit configured to excite the starting high-voltage pulse in the secondary winding of the starting transformer;
The start-up transformer has a waveform of a start-up high-voltage pulse excited by the secondary winding due to an instantaneous current flowing from the start-up capacitor to the primary winding of the start-up transformer. The first high-voltage pulse component excited by the secondary winding of the start-up transformer and the fact that current does not flow through the primary winding of the start-up transformer immediately after the generation of the first high-voltage pulse. Attenuation oscillation waveform is obtained by synthesizing the second high-voltage pulse component excited by the back electromotive force on the secondary winding of the starting transformer, and the high-voltage pulse components overlap each other with a phase shift. A discharge lamp lighting device characterized by being a transformer in which connectivity of at least one of both windings is adjusted so that a pulse portion of a vibration waveform is formed. The breakdown element of the startup circuit is an element having a breakdown voltage higher than the voltage of the predetermined value applied to the discharge lamp from the DC booster circuit before starting the lighting of the discharge lamp,
The DC boost circuit has a primary winding to which a DC voltage of the DC power supply is periodically applied, and a boost transformer having a first secondary winding and a second secondary winding; A first rectifying diode and a first smoothing capacitor connected in series between both ends of the first secondary winding of the step-up transformer, and a first connected to one end of the second secondary winding. A circuit comprising two rectifying diodes,
A DC voltage input to the inverter circuit is output from one end on the high potential side of the first smoothing capacitor of the DC booster circuit, and a DC is charged from the second rectifier diode to the starter capacitor of the starter circuit. The discharge lamp lighting device according to claim 1, wherein a voltage is output.   3. The discharge lamp lighting device according to claim 2, wherein the other end of the second secondary winding of the DC booster circuit is connected to one end on the high potential side of the first smoothing capacitor.   A second smoothing capacitor for smoothing the DC voltage output from the second rectifying diode of the DC boosting circuit is provided connected to the second rectifying diode in the vicinity of the second rectifying diode. The discharge lamp lighting device according to claim 2 or 3, wherein

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