JP2006286460A - High pressure discharge lamp lighting device - Google Patents

Abstract

To provide a lighting device for a high-pressure discharge lamp of a single-end mold, capable of obtaining a high-pressure discharge lamp having a long life without causing uneven discharge and flickering and without uneven discharge.
When an AC lamp current is supplied to a pair of electrodes of a high pressure discharge lamp to light the high pressure discharge lamp, a current pulse is generated at a predetermined fraction of a half cycle of the lamp current. In the high pressure discharge lamp lighting device in which the polarity of the lamp current is made the same as the polarity of the lamp current, and the current pulse is superimposed on the lamp current in a portion after the half cycle in which the current pulse is generated, the temperature difference between the pair of electrodes Based on this, a lighting device for a high pressure discharge lamp in which the height of the current pulse is asymmetric.
[Selection] Figure 1

Description

  The present invention relates to a lighting device used for lighting a high-pressure discharge lamp of a single-end mold, such as a high-pressure discharge lamp, particularly an automotive headlamp.

  In a conventional lighting device for a high pressure discharge lamp, for example, as described in Patent Document 1, the input side of a voltage supply source that generates a direct current is connected to a power supply for supplying a voltage. Is connected to a commutator for converting a direct current into an alternating current. Then, the high-pressure discharge lamp connected to the output side is lit by the lamp current having an AC waveform.

  In such a lighting device that lights a high-pressure discharge lamp with an alternating lamp current, the polarity of the lamp current is reversed, so it is difficult to balance the temperature of the electrodes, and the stability of the discharge is poor, and therefore a flicker phenomenon called flicker occurs. It was happening. This flicker phenomenon is particularly remarkable in a high-pressure discharge lamp used for an automobile headlamp. With respect to this problem, in the lighting device described in Patent Document 1, current pulse generating means is connected to the voltage supply source. By superimposing a current pulse having the same polarity as the lamp current on the latter half of the lamp current by this current pulse generating means, the stability of the discharge is improved and flickering is suppressed.

  However, in such a high-pressure discharge lamp using the lighting method described in Patent Document 1, assuming that the lighting is performed with constant power, the lamp current is increased in the time zone other than that time by the amount of addition of the pulsed current. Must be reduced. As a result, it was found that the discharge becomes unstable and flickering occurs.

  In particular, when a high-pressure discharge lamp that does not enclose mercury is lit, it is necessary to extend the power-on time at the beginning of lighting and to flow a large current during that period, compared to a high-pressure discharge lamp that encloses mercury. Therefore, it is necessary to design the electrode thick so that the electrode does not deform or dissolve during that time, which further increases the instability of the discharge and the occurrence of flicker.

  On the other hand, a high-pressure discharge lamp of a single-end mold such as an automobile headlamp has a structure as shown in FIG. That is, metal foils 33a and 33b are connected to electrodes 32a and 32b provided facing the inside of the arc tube 31, and external lead wires 34a and 33b for applying electric power to the metal foils 33a and 33b from the outside. 34b is connected. As shown in FIG. 3, in the single-piece high pressure discharge lamp having such a structure, heat is actively dissipated in the direction of the base, but the discharge in the opposite direction is overwhelmingly less than that of the former. The temperatures at the tips of the electrodes 32a and 32b are different. This difference in the tip temperature of the electrode causes non-uniform emission distribution and significantly shortens the life of the discharge lamp.

In order to solve this problem, in Patent Document 2, the width of the rectangular wave current applied to the high pressure discharge lamp is changed. However, such a high-pressure discharge lamp cannot prevent the instability and flickering of the discharge described above.
JP 10-501919A (pages 7 to 11, FIGS. 1, 2 and 4) JP-A-6-163167 (FIGS. 1 and 2)

  The present invention has been made in view of the problems of the conventional single-ended high-pressure discharge lamp as described above, and to obtain a high-pressure discharge lamp that has a stable discharge without flickering and has a long life with no uneven discharge. An object of the present invention is to provide a lighting device for a high-pressure discharge lamp of a single-end mold that can be used.

  According to claim 1 of the present invention, when an AC lamp current is supplied to a pair of electrodes of a high pressure discharge lamp to light the high pressure discharge lamp, a current pulse is generated at a predetermined fraction of a half cycle of the lamp current. In the lighting device for a high-pressure discharge lamp, the current pulse having the same polarity as the lamp current and the current pulse being superimposed on the lamp current in a portion after the half cycle in which the current pulse is generated, There is provided a high pressure discharge lamp lighting device characterized in that the height of the current pulse is asymmetric based on the temperature difference between the electrodes.

  ADVANTAGE OF THE INVENTION According to this invention, the lighting device of the single neck type | mold high pressure discharge lamp which can obtain the high pressure discharge lamp which discharges stably and does not produce flicker, and discharge is not biased and has a long life is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a circuit configuration example of a lighting device according to an embodiment of the present invention. The lighting device for the high pressure discharge lamp includes a DC power source V1, a switch SW1, a DC / DC converter circuit 1, an output voltage detection circuit 2, an output current detection circuit 3, a DC / AC converter circuit 4, an igniter 5, and a one-piece mold high pressure. It is comprised from the discharge lamp 6 and the control circuit which controls these.

  The transformer T included in the DC / DC converter circuit 1 includes a primary-side transformer T1 and secondary-side transformers T2 and T3. In the DC / DC converter circuit 1 that performs step-down or step-up, the primary side of the transformer T is constituted by the capacitor C1, the switching element Q1, the power MOS drive circuit 11, the PWM comparator 12, the sawtooth wave generation circuit 13, and the transformer T1. The The transformer T2, the diode D1, and the capacitor C2 constitute the secondary side of the transformer T connected to the DC / AC inverter circuit 4. Further, the transformer T3, the diode D2, and the capacitor C3 constitute a secondary side of the transformer T connected to the igniter 5.

  The connection relationship on the primary side of the transformer T will be described. For example, the switching element Q1, which is a MOSFET, is connected in series to the DC power supply V1, the switch SW1, and the transformer T1, and the power MOS drive circuit 11 is connected to the gate of the switching element Q1.

  The output terminal of the PWM comparator 12 is connected to the power MOS drive circuit 11, and the output terminal of the sawtooth wave generation circuit 13 is connected to the non-inverting input terminal of the PWM comparator 12. The capacitor C1 is connected in parallel to the DC power supply V1 through the switch SW1. As described in detail later, this embodiment is characterized in that the width of the pulse supplied from the PWM comparator 12 to the power MOS drive circuit 11 of the DC / DC converter circuit is changed.

  The connection relationship on the secondary side of the transformer T connected to the DC / AC inverter circuit 4 will be described. The transformer T2 is connected in series to the diode D1, and the capacitor C2 is connected in parallel to the transformer T2 via the diode D1. Next, the connection relationship on the secondary side of the transformer T connected to the igniter 5 will be described. The transformer T3 is connected in series with the midpoint of the transformer T2 and the diode D1, and the diode D2, and constitutes an output to the igniter 5. The capacitor C3 is connected in parallel to the transformer T3 via the diode D2.

  The output voltage detection circuit 2 includes resistors R1, R2 and R3 connected in series. The output voltage detection circuit 2 is connected to the output side of the capacitor C2 and in parallel to the capacitor C2. The output current detection circuit 3 includes a resistor R4, and is connected between the output voltage detection circuit 2 and the DC / AC inverter circuit 4 and on the low voltage side.

  The DC / AC inverter circuit 4 includes switching elements Q2, Q3, Q4, and Q5 made of, for example, MOSFETs, drive circuits 14, 15, 16, and 17, a rectangular low frequency generation circuit 18, a buffer BUF, and an inverter INV. . As for the connection relationship, switching elements Q2 and Q3 and switching elements Q4 and Q5 are respectively connected in series, and they are connected in parallel to the output terminal of the DC / DC converter circuit 2, resulting in a so-called full bridge circuit configuration. Yes.

  An output terminal of the DC / AC inverter circuit 4 is provided from a connection point between the switching elements Q2 and Q3 and the switching elements Q4 and Q5, and is connected to an input terminal of the igniter 5. Driving circuits 14, 15, 16, and 17 are connected to the gates of the switching elements Q2, Q3, Q4, and Q5, respectively. The driving circuits 15 and 16 have a buffer BUF, and the driving circuits 14 and 17 have an inverter INV. Further, it is connected to the rectangular low frequency generation circuit 18 via SW2 described later.

  The igniter 5 receives the AC output of the DC / AC converter circuit 4 and turns on the high-pressure discharge lamp 6 of a one-end mold.

  The high-pressure discharge lamp 6 of a single-end mold is a lamp that does not contain mercury in the discharge space and emits light by evaporating a metal halide and a rare gas instead. The igniter 5 is connected to the output terminal of the DC / AC inverter circuit 4. They are connected via a pulse transformer (not shown).

  The control circuit for controlling the switching element Q1 of the DC / DC converter circuit 1 includes a differential amplifier circuit 7, a reference voltage source V2, a resistor R8, a lighting detection circuit 21, a lighting time timer 22, and target power. Value setting circuit 23, division circuit 24, turn-off time timer 25, switch SW2, differential amplifier circuit 8, delay circuit 26, logic circuit 27, switch SW3, flip-flop 28, transistor TR1, resistors R9, R10, R11, R12 , R13, R14, R15 are used.

  When lighting is detected by the lighting detection circuit 21, the detection signals are input to the lighting time timer 22 and the extinguishing time timer 25. The lighting time timer 22 outputs the output of the rectangular low frequency generation circuit 18 after a predetermined time. The switch SW2 is controlled so as to be supplied to the buffer BUF and the inverter INV.

  Each of the differential amplifier circuit 7 and the differential amplifier 8 includes an operational amplifier, a diode, a resistor, and a capacitor. A voltage detection point between the resistor R1 of the output voltage detection circuit 2 and the resistors R2 and R3 is connected to the non-inverting input terminal of the operational amplifier of the differential amplifier circuit 7. A reference voltage source V2 is connected to the inverting input terminal of the operational amplifier, and a diode D3 is connected in series to the output terminal of the operational amplifier. A resistor and a capacitor are connected in parallel to the series connection of the operational amplifier and the diode of the differential amplifier 7. The output terminal of the differential amplifier circuit 7 is connected to the inverting input terminal of the PWM comparator 12 via the resistor R8.

  A voltage detection point between the resistor R4 of the output current detection circuit 3 and the DC / AC inverter circuit 4 is connected to the non-inverting input terminal of the operational amplifier of the differential amplifier circuit 8. A division circuit 24 is connected to the inverting input terminal of the operational amplifier.

  The division circuit 24 is connected to a voltage detection point between the resistors R2 and R3 of the output voltage detection circuit 2 and a target power value setting circuit 23 via a lighting detection circuit 21 and a lighting time timer 22. ing. Further, a lighting detection circuit 21 is connected to the lighting time timer 22 via a light-out timer 23. The lighting time timer 22 is connected to a switch SW2 that switches after a predetermined time when an input is input. The target power value setting circuit 23 is connected to a switch SW3 that is opened and closed when an input is input. The output terminal of the differential amplifier circuit 8 is connected to the inverting input terminal of the PWM comparator 12 via the resistor R8.

  One end of the resistor R9 is connected to the inverting input terminal of the PWM comparator 12. The other end of the resistor R9 is connected to one end of the resistor R10, and the other end of the resistor R10 is connected to the negative terminal of the DC power supply V1.

  On the other hand, the output terminal of the rectangular low frequency generation circuit 18 and the output terminal of the delay circuit 26 are two inputs of the logic circuit 27. This logic circuit 27 is a circuit that outputs an inverted signal of exclusive OR. The output terminal of the logic circuit 27 is connected to one end of the switch SW3. The other end of the switch SW3 is connected to the input terminal of the flip-flop 28, and the two output terminals of the flip-flop 28 are connected to one ends of the resistor R11 and the resistor R14, respectively. The other end of the resistor R11 is connected to the base of the transistor TR1 and one end of the resistor R12. The other end of the resistor R14 is connected to the base of the transistor TR2 and one end of the resistor R15. The other end of the resistor R12 and the other end of the resistor R15 are connected to the minus terminal of the DC power supply V1. The collector of the transistor TR1 is connected to the connection point between the resistor R9 and the resistor R10. The collector of the transistor TR2 is connected to the connection point between the resistor R9 and the resistor R10 via the resistor R13. The emitters of the transistors TR1 and TR2 are connected to the negative terminal of the DC power supply V1.

  The configuration of the transistor TR1 and the resistors R11 and R12 is the same as the configuration of the transistor TR2, the resistor R14, and the resistor R15. The collector of the transistor TR1 is directly connected to the connection point between the resistor R9 and the resistor R10, and the collector of the transistor TR2 is connected via the resistor R13.

  Next, the circuit operation of this embodiment of the present invention will be described. When the switch SW1 is closed, for example, a voltage is generated in the capacitor C1 by the DC power source V1 that is a vehicle battery of tens to tens of volts. This capacitor C1 functions to suppress minute voltage fluctuations due to changes in the output current of the DC power supply.

  When a voltage is generated in the capacitor C1, although not shown, the voltage is supplied to the operational amplifier of the differential amplifier circuit 7. At this time, the voltage at the non-inverting input terminal of this operational amplifier is zero, and since the reference voltage source V2 is connected to the inverting input terminal, a low level is output from this operational amplifier. This voltage is input to the inverting input terminal of the PWM comparator 12 via the diode D3 and is compared with the sawtooth wave output from the sawtooth wave generating circuit 13, and a PWM wave is generated as the output of the PWM comparator 12. The output voltage of the PWM comparator 12 is input to the power MOS drive circuit 11 to switch the switching element Q1.

  On the secondary side of the transformer T, a boosted voltage is generated by the switching operation of the switching element Q1 on the primary side. The current due to the voltage generated in the transformer T2 charges the capacitor C2 via the diode D1. The voltage across the capacitor C2 is detected by the resistors R1 and R2 and the resistor R3 of the output voltage detection circuit 2, and the detection result is input to the non-inverting input terminal of the operational amplifier of the differential amplifier circuit 7. .

  The reference voltage source V2 is connected to the input of the inverting input terminal of the operational amplifier of the differential amplifier 7. When the input voltage value is lower than the reference voltage source V2, the input is input to the inverting input terminal of the PWM comparator 12. Therefore, the voltage on the secondary side of the transformer T is increased to increase the voltage of the capacitor C2. Here, the resistor connected in parallel to the operational amplifier is inserted for adjusting the gain of the operational amplifier, and the capacitor C6 is used for delaying the phase of the output and stabilizing the operation of the entire lighting device. ing.

  The current due to the voltage generated in the transformer T3 charges a capacitor (not shown) of the igniter 5 through the diode D2 and the resistor R5. This capacitor is mainly used as a smoothing capacitor for smoothing the voltage from the transformer T3. When the voltage of this capacitor becomes sufficiently high, current starts to flow through a pulse transformer (not shown). Thereby, a high-pressure pulse is applied to the high-pressure discharge lamp 6, and the high-pressure discharge lamp 6 undergoes dielectric breakdown, causing glow discharge. Although not shown here, a capacitor is connected in parallel with the input terminal of the igniter 5, and a filter for preventing the high-pressure pulse applied to the high-pressure discharge lamp 6 from flowing back to the DC / AC inverter circuit 4. As this capacitor works. Up to this point, the switch SW2 is in a state where the connection between the drive circuits 14, 15, 16, and 17 and the rectangular low frequency generation circuit 18 is cut off.

  When glow discharge occurs due to dielectric breakdown of the high-pressure discharge lamp 6, the charge charged in the capacitor C <b> 2 flows rapidly to the high-pressure discharge lamp 6 as a lamp current via the DC / AC inverter circuit 4. Due to this current, the high pressure discharge lamp 6 shifts from glow discharge to arc discharge and starts to light. The lighting immediately after this maintains a lighting state called DC lighting that maintains the same polarity for a relatively long time.

  Here, in the output voltage detection circuit 2, the voltage is detected by the resistance R 1 and the voltage division of the resistance R 2 and the resistance R 3, and this voltage division voltage is input to the lighting detection circuit 21. In the lighting detection circuit 21, the charge of the capacitor C2 is supplied to the high pressure discharge lamp 6 to detect that the voltage has dropped. By this detection, the lighting time timer 22 starts to count, and the switch SW2 is switched after a predetermined time has elapsed from the start of timing. As a result, the drive circuits 14 to 17 and the rectangular low frequency generation circuit 18 are connected.

  When the switch S2 is switched, the rectangular low frequency is input to the drive circuits 14 to 17 through the buffer BUF and the inverter INV, and the switching elements Q2 to Q5 are on / off controlled. This on / off control is performed in two states in which the switching elements Q3 and Q4 are turned off when the switching elements Q2 and Q5 are turned on, and the switching elements Q3 and Q4 are turned on when the switching elements Q2 and Q5 are turned off. Q2 to Q5 repeat polarity inversion.

  Due to the polarity inversion operation of the switching elements Q2 to Q5, substantially rectangular wave AC power is generated on the output side of the DC / AC inverter circuit 4, and the high-pressure discharge lamp 6 shifts to lighting when stable.

  Here, the “substantially rectangular wave” refers to a case where the waveform has a waveform close to a flat characteristic, such as an instantaneous rise, fall, or the like that a rectangular wave has. That is, the waveform includes a waveform in which the rise and fall takes about several microseconds, or has a flat characteristic, but a certain portion protrudes or is depressed.

  Next, constant power control of the high pressure discharge lamp 6 will be described. This constant power control is performed based on the measurement results of the output voltage detection circuit 2 and the output current detection circuit 3. The voltage detection result of the output voltage detection circuit 2 is input to the division circuit 24. Furthermore, the power (target power value) to be supplied to the high-pressure discharge lamp 6 in that state is also input to the dividing circuit 24 by the target power value setting circuit 23 that operates according to the output from the lighting time counting circuit 22. Therefore, in the division circuit 24, the target power value is divided by the potential at the connection point between the resistors R1 and R2, and the division circuit 24 outputs a signal for setting the ideal current value. This output signal is input to the inverting input terminal of the operational amplifier of the differential amplifier circuit 8.

  On the other hand, the current detection result of the current detection circuit 3 is input to the non-inverting input terminal of the operational amplifier of the differential amplifier circuit 8, and a signal resulting from the comparison is input to the inverting input terminal of the PWM comparator 12. The output of the PWM comparator 12 is input to the power MOS drive circuit 11, and the duty ratio of the switching element Q1 changes according to this input signal. As a result, the high-pressure discharge lamp 6 is subjected to constant power control.

  The inverting input terminal of the PWM comparator 12 is connected to a circuit for sending a signal for increasing the voltage to the switching element Q1 a predetermined time before polarity inversion, and for sending a signal for stopping the voltage increase signal at the time of polarity inversion. ing. The operation of this circuit will be described with reference to the waveform diagram shown in FIG. 2 to increase the voltage of the DC / DC converter circuit during polarity inversion.

  The rectangular wave output from the rectangular low frequency generation circuit 18 (FIG. 2A) and the rectangular wave generated from the delay circuit 26 having the same waveform as the output of the rectangular low frequency generation circuit 18 and delayed by a predetermined time (FIG. In the logic circuit 27, EX-NOR, that is, exclusive OR is inverted and a pulse-like output waveform is obtained (FIG. 2 (c)).

  The pulse-like output waveform shown in FIG. 2C is input to the flip-flop circuit 28 via the switch SW3. The waveform shown in FIG. 2 (d) is output to the Q1 output terminal of the flip-flop circuit 28, and the waveform shown in FIG. 2 (e) is output to the Q2 terminal. As shown in the waveform diagram of FIG. 2, the output pulse of the logic circuit 27 is distributed by the flip-flop circuit 28.

  If the output (d) of the flip-flop circuit Q1 is at a low level, the transistor TR1 is in an off state, but if it is at a high level, the transistor TR1 is in an on state, and the inverting input terminal of the PWM comparator 12 is a resistor R8. And the divided potential of the resistor R9. When the output (e) of the flip-flop circuit Q2 is at a low level, the transistor TR2 is in an off state. However, when the output is high, the transistor TR2 is in an on state, and the inverting input terminal of the PWM comparator 12 is It becomes the divided potential of the resistor R8, the resistor R9, and the resistor R13.

  Therefore, as shown in FIG. 2F, waveforms having cuts dp1 and dp2 having different depths are alternately input to the inverting input terminal of the PWM comparator 12. This waveform is input from the PWM comparator 12 to the power MOS drive circuit 11 as a change in duty ratio.

  Therefore, the lamp current of the high pressure discharge lamp has a waveform as shown in FIG. Superimposed pulses H1 and H2 are provided at the rear end of the lamp current waveform, and the magnitudes h1 and h2 of these pulses are different and appear alternately.

  FIG. 3 shows the configuration of a single-ended high pressure discharge lamp 6. In this high-pressure discharge lamp 6 of a single-end mold, lead wires 32 a and 32 b are connected to a base 31, and metal foils 33 a and 33 b are connected to this, and these metal foils 33 a and 33 b are connected to the discharge space 34. The electrodes 35a and 35b projecting from each other are connected.

  Since it is a single-piece base, heat dissipation differs between the left and right, making it difficult to make the electrode temperatures equal. Therefore, it is easy to cause melting with the electrode having a higher temperature and sputtering with the electrode having a lower temperature.

  Therefore, a lamp current is passed through the high-pressure discharge lamp 6 so that the large superimposed pulse H1 shown in FIG. 2 (g) is applied to the electrode 35b. If it does in this way, it will become possible to make it discharge so that the voltage of the same level may be applied to both electrodes of the high-pressure discharge lamp 6 of a single neck mold.

  Waveform cutting depths dp1 and dp2 applied to FIG. 2 (f) are the voltage dividing ratio of the values of the resistors R8 and R9 shown in FIG. 1, the sum of the values of the resistors R8 and R9, and R13. Therefore, by adjusting the value of the resistor R13, the depths of cutting dp1 and dp2 can be set to appropriate values.

  In this embodiment, the lamp current is superimposed immediately before the polarity inversion to heat the electrode and then the polarity inversion is performed. Therefore, such as a high-pressure discharge lamp for a headlamp of an automobile in which a large amount of power is input at the beginning of lighting. Even with a discharge lamp using relatively thick electrodes, flickering can be prevented. Furthermore, in the case of an automotive headlamp that accelerates the rise of the luminous flux by supplying a power larger than the rated power at the beginning of lighting, the maximum power is 75 W, for example, as shown in FIG. A power of 35 W has been put into practical use, but if the maximum power when the lamp current is superimposed is 75 W or less, there is no need to increase the element withstand capability. That is, it is possible to prevent occurrence of flickering in the high-pressure discharge lamp without increasing the cost and size of the lighting device.

  By the way, in the above embodiment, the height of the pulse to be superimposed on the lamp current applied to the high pressure discharge lamp 6 of the single die is high in the current supplied to the electrode 35a far from the base 31 and close to the base 31. The current supplied to the electrode 35b is changed to be lower.

  However, in the present invention, it is possible to change the width of these pulses instead of changing the height of the superimposed pulses. FIG. 4 shows a current waveform applied to the electrode of the high-pressure discharge lamp 6 of a single-end mold in the case of this embodiment. In this example, the width w1 of the pulse H3 superimposed on the current applied to the electrode 35a farther from the base is wider than the width w2 of the pulse H4 superimposed on the current applied to the electrode 35b closer to the base. In order to change the width of the superimposed pulse in this way, the pulse width output from the flip-flop circuit 28 is changed in the circuit shown in FIG.

  Thus, the discharge by the electrode 35a and the discharge by the electrode 35b can be performed uniformly, and the life of the high-pressure discharge lamp 6 can be extended.

  As described above, the switch SW1 is closed to increase the output current before one current direction is finished and switched to the other, the polarity reversal operation is performed after a predetermined time, and the switch SW1 is opened when the polarity reversal is finished. Let At the time of polarity reversal in another direction, the switch SW2 is closed and the polarity reversal is performed after a predetermined time has elapsed, and the switch SW2 is opened when the polarity reversal is completed. As a result, as shown in FIG. 2G, it is possible to generate a waveform in which the height (amount) of the superimposed pulse current is different for each polarity.

  On the other hand, in order to change the superposition amount in terms of time, it is possible to generate a waveform as shown in FIG. 4 by making the time when the switch SW1 is closed and the time when the switch SW2 are closed similarly. It becomes. In this case, it is also possible to use both the switch SW1 and the switch SW2, and for example, a time change can be given to a port such as a microcomputer.

  By the way, it is also possible to make the discharge from the electrodes 35a and 35b uniform by making both the height and width of the pulse superimposed on the current applied to the discharge lamp asymmetric. In addition, the present invention can be implemented in combination as appropriate, such as changing the width of the superimposed pulse when it is not desired to change the lamp current height, and changing the height of the superimposed pulse when not desired to change the lamp current frequency. It is possible.

The figure which shows the circuit structural example of the lighting device by one Embodiment of this invention. The wave form diagram for demonstrating operation | movement of the lighting device of one Embodiment of this invention shown in FIG. The figure which shows the structure of the one-piece metal mold | die high pressure discharge lamp to which this invention is applied. The wave form diagram for demonstrating other embodiment of this invention. The figure which shows the characteristic of the input electric power in the high pressure discharge lamp which does not contain the mercury for motor vehicle headlamps.

Explanation of symbols

1 ... DC / DC converter circuit,
2 ... Output voltage detection circuit,
3 ... Output current detection circuit,
4 ... DC / AC converter circuit,
5 ... Igniter,
6 ... High pressure discharge lamp,
11: Power MOS drive circuit,
13 ... Serrated wave generation circuit,
14, 15, 16, 17... Drive circuit,
BUF ... Buffer
INV: Inverter,
18 ... rectangular low frequency generator,
21 ... lighting detection device,
22 ... Lighting time timer 23 ... Target power value setting circuit,
24: Dividing circuit,
25 ... Time-out timer,
26 ... delay circuit,
27. Logic circuit,
28 ... flip-flop circuit 31 ... base,
32a, 32b ... lead wires,
33a, 33b ... metal foil,
34 ... Vacuum part,
35a, 35b ... electrodes,
V1 ... DC power supply,
V2 ... reference voltage source,
SW1, SW2, SW3 ... switch,
T, T1, T2, T3 ... transformer,
Q1, Q2, Q3, Q4 ... switching elements,
D1, D2 ... diodes,
C1, C2 ... capacitors,
TR1 ... transistor,
R1, R2, R3, R4, R5, R8, R9, R10, R11, R12, R13, R14, R15... Resistors.

Claims (2)

When supplying an AC lamp current to a pair of electrodes of a high pressure discharge lamp to light the high pressure discharge lamp, a current pulse is generated at a predetermined fraction of a half cycle of the lamp current, and the polarity of the current pulse is In the lighting device of the high-pressure discharge lamp, the lamp current is made the same as the polarity of the lamp current, and the current pulse is superimposed on the lamp current in a portion after the half cycle in which the current pulse is generated.
A lighting device for a high-pressure discharge lamp, wherein the height of the current pulse is asymmetric based on a temperature difference between the pair of electrodes. When supplying an alternating lamp current to a pair of electrodes of a high pressure discharge lamp to light the high pressure discharge lamp, a current pulse is generated at a predetermined fraction of a half cycle of the lamp current, and the polarity of the current pulse is In the lighting device of the high-pressure discharge lamp, the lamp current is made the same as the polarity of the lamp current, and the current pulse is superimposed on the lamp current in a portion after the half cycle in which the current pulse is generated.
A lighting device for a high-pressure discharge lamp, wherein the current pulses have different widths based on a temperature difference between the pair of electrodes.

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