JP2005004972A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can generate a high voltage pulse necessary for starting the discharge lamp without using a high withstand voltage diode, a film capacitor with large current resistance, and furthermore a self arc-extinguishing switching means and which is of small size and low cost. <P>SOLUTION: This is a discharge lamp lighting device which is constructed of a DC power supply, a DC-DC converter circuit for controlling supply power to the discharge lamp of a load by stepping up or stepping down the DC power supply, an inverter circuit for converting the stepped up or stepped down DC voltage into AC voltage and supplying it to the discharge lamp of the load, and an ignitor circuit for impressing a high voltage pulse at the starting of the discharge lamp of the load. The ignitor circuit consists of a flyback voltage generating circuit that has a pulse transformer and an active switching means with a power input of the DC power supply. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp lighting device that lights a high-intensity discharge lamp used in automobiles, projectors, lighting, and the like.
[0002]
[Prior art]
FIG. 6 shows a circuit configuration of a conventional discharge lamp lighting device. E in the figure is a direct current power source comprising an in-vehicle battery or the like. Reference numeral 1 denotes a DC-DC converter circuit that steps up or down a DC power supply E and controls power supplied to a discharge lamp DL as a load, and includes a switch means Q1, a transformer T1, a diode D1, and a capacitor C1. . Reference numeral 2 denotes an inverter circuit for converting a DC voltage into an AC voltage, and is composed of a full bridge circuit of switch means Q2 to Q5. Reference numeral 3 denotes an igniter circuit that generates a high-pressure pulse necessary for starting the discharge lamp DL as a load. The igniter circuit 3 includes a charging circuit 31 and a pulse generation circuit 32. The charging circuit 31 includes diodes D2 and D3 for voltage doubler rectification, capacitors C2 and C3, and a resistor R1 for limiting charging current. . The pulse generation circuit 32 includes a pulse transformer T2 and self-extinguishing switch means X1.
[0003]
FIG. 7 shows operation waveforms of the conventional igniter circuit 3. The charging circuit 31 of the igniter circuit 3 is composed of a voltage doubler rectifier circuit, and a charging current IR flows when the polarity of the input voltage V2 of the igniter circuit 3 is alternated. When the voltage of the capacitor C2 is VC2 and the voltage of the capacitor C3 is VC3, the capacitor is charged like the capacitor charging voltage VC2 + VC3 in FIG. 9, and when the charging voltage is charged to a predetermined voltage, the self-extinguishing switch means X1 (In the figure, it is a thyristor, but a triac or a discharge gap is also possible) is turned on to generate a pulse voltage via the pulse transformer T2. When the discharge lamp DL is activated by the generation of the pulse voltage, the inverter output voltage V2 is decreased and the igniter circuit 3 is stopped. However, if the discharge lamp DL is not activated, the inverter output voltage V2 is not decreased and the charging current IR flows again. .
[0004]
As other conventional techniques, those using an inductor and a switching element (circuit symbol is MOS-FET) for the igniter, and those using a pulse transformer and a switching element (circuit symbol is a thyristor) for the igniter circuit are disclosed. (For example, Patent Documents 1 and 2).
[0005]
[Patent Document 1]
JP 2002-352978 A (page 4, FIG. 1)
[Patent Document 2]
JP 2000-340374 A (page 3, FIG. 1)
[0006]
[Problems to be solved by the invention]
In the igniter circuit 3 of the discharge lamp lighting device shown in FIG. 6, the diodes D2 and D3 are high voltage diodes, and the capacitors C2 and C3 are film capacitors that can withstand a large pulse current. Since these parts have a relatively large shape, there is a problem that it is difficult to reduce the size of the igniter circuit 3.
[0007]
In order to turn off the self-extinguishing switch means X1 which is the main switch, it is necessary to make the holding current IH or less. It is often placed in a high temperature state, and the holding current IH has a low value at a high temperature as shown in FIG. In order to turn off the self-extinguishing switch means X1, the circuit must be designed so that the peak value of the charging current IR is smaller than the holding current IH, and the charging current IR is suppressed in consideration of the operating temperature range. There is also a problem that the charging time of the capacitors C2 and C3 becomes long.
[0008]
The problem to be solved by the present invention is that a pulse voltage required for starting a discharge lamp without using a high voltage diode, a large current resistant film capacitor, and a self-extinguishing switch means having many restrictions in circuit design. An object of the present invention is to provide a small and low-cost discharge lamp lighting device that can be generated.
[0009]
[Means for Solving the Problems]
(1) A discharge lamp lighting device according to the present invention includes a DC-DC converter circuit that controls the power supplied to a discharge lamp that is a load by stepping up or down a DC power supply, and the DC voltage that has been stepped up or down into an AC voltage. A discharge lamp lighting device comprising an inverter circuit for converting and supplying to a discharge lamp as a load, and an igniter circuit for applying a high-pressure pulse at the start of the discharge lamp as a load,
The igniter circuit is characterized in that it forms a flyback voltage generation circuit having a DC power supply as an input and having a pulse transformer and active switch means.
[0010]
(2) Another discharge lamp lighting device according to the present invention includes a DC-DC converter circuit that controls a power supplied to a discharge lamp as a load by stepping up or down a direct current power source, and an alternating current from the boosted or stepped down direct current voltage. A discharge lamp lighting device comprising an inverter circuit that converts the voltage into a discharge lamp that is a load, and an igniter circuit that applies a high-pressure pulse at the start of the discharge lamp that is the load,
The igniter circuit has a DC voltage obtained by rectifying the output of the inverter circuit as an input, and constitutes a flyback voltage generation circuit including a pulse transformer and active switch means.
[0011]
(3) Another discharge lamp lighting device of the present invention includes an inverter circuit that converts a DC power source into an AC voltage and supplies the AC voltage to a discharge lamp that is a load, and an igniter circuit that applies a high-pressure pulse when starting the discharge lamp that is a load. A discharge lamp lighting device comprising:
The igniter circuit includes a flyback voltage generation circuit having the DC power supply as an input and including a pulse transformer and active switch means.
[0012]
(4) Another discharge lamp lighting device of the present invention includes a DC-DC converter circuit that boosts a DC power source to control power supplied to a discharge lamp that is a load, and converts the boosted DC voltage into an AC voltage. A discharge lamp lighting device comprising an inverter circuit for supplying a discharge lamp as a load, and an igniter circuit for applying a high-pressure pulse at the start of the discharge lamp as a load,
The igniter circuit has a flyback voltage generation circuit including a pulse transformer and active switch means, which receives the boosted DC voltage as an input.
[0013]
(5) In the discharge lamp lighting device according to any one of the above (1) to (4), an insulated gate bipolar transistor is used as the active switch means.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the configuration of Embodiment 1 of the present invention. In FIG. 1, E is a direct current power source, which is composed of a vehicle battery or a direct current voltage obtained by rectifying a commercial alternating current voltage. A DC-DC converter circuit 1 that boosts or steps down the DC power supply E and controls power supplied to the discharge lamp DL as a load, an inverter circuit 2 that converts the boosted or stepped-down DC voltage into an AC voltage, and flyback The igniter circuit 3 includes a voltage generation circuit 33 and a drive / control circuit 4.
[0015]
A configuration of the DC-DC converter circuit 1 shown in FIG. 1 will be described. The positive side of the DC power source E is connected to one end of the primary winding of the transformer T1. The other end of the primary winding of the transformer T1 is connected to the drain of the switch means Q1 using a MOS field effect transistor (MOSFET). The source of the switch means Q1 is connected to the ground GND and to the negative electrode side of the DC power supply E. The gate of the switch means Q1 is connected to the c terminal. One end of the secondary winding of the transformer T1 is connected to the ground GND, and the other end is connected to the anode of the diode D1. The cathode of the diode D1 is connected to one end of the output capacitor C1. The other end of the output capacitor C1 is connected to the ground GND, and a current detection resistor R2 is connected to the other end.
[0016]
Next, the inverter circuit 2 will be described. This inverter circuit 2 is obtained by full-bridge connecting four switch means Q2 to Q5 made of MOSFETs to the output V1 of the DC-DC converter circuit 1 described above, the switch means Q2 and Q5 are turned on, and Q3 and Q4 Is driven in such a manner that the first state where the switch means Q2 and Q5 are turned off and the second state where the switch means Q3 and Q4 are turned on are alternately reversed. Therefore, a square wave AC voltage V2 is output.
[0017]
Next, the flyback voltage generation circuit 33 constituting the igniter circuit 3 will be described. In the flyback voltage generation circuit 33, the primary winding of the pulse transformer T2 and the active switch means Q6 are connected in series, and a capacitor C4 and a diode D4 are connected in parallel between the collector and emitter of the active switch means Q6. The diode D4 is connected in the direction in which the reverse current of the active switch means Q6 flows. The secondary winding of the pulse transformer T2 is connected in series between the output of the inverter circuit 2 and the discharge lamp DL. During the ON period of the active switch means Q6, the excitation current gradually increases from the DC power source E to the primary winding of the pulse transformer T2, and the excitation energy is stored. Excitation energy is released at the moment when the active switch means Q6 is turned off, and a flyback voltage is generated between the windings. A flyback voltage having a resonance period determined by the exciting inductance of the primary winding and the capacitance of the capacitor C4 (the capacitance existing in the winding of the active switch means Q6 and the pulse transformer T2 also includes an equivalent action) appear. Since the excitation energy stored in the ON period of the active switch means Q6 appears as a voltage waveform compressed in a short resonance period, the peak value of the flyback voltage VF1 generated between the primary windings is DC The voltage is easily boosted to several tens of times the voltage of the power supply E. Further, the flyback voltage VF1 is boosted by the winding ratio of the pulse transformer T2, and is output as an igniter voltage VF2 between the secondary windings.
[0018]
Next, the drive / control circuit 4 will be described. The drive / control circuit 4 detects and controls the state of each part of the DC-DC converter circuit 1, the inverter circuit 2, and the flyback voltage generation circuit 33, and sends out drive signals for the switch means Q1 to Q6. The a terminal detects the DC power supply voltage, and the b terminal is connected to the ground GND. The d terminal detects the current (corresponding to the discharge lamp current) output from the DC-DC converter circuit 1 to the inverter circuit 2 by the current detection resistor R2, and the e terminal detects the output voltage V1 of the DC-DC converter circuit 1. To detect. The k terminal detects the collector voltage of the active switch means Q6 of the flyback voltage circuit 33 (the polarity is different from the flyback voltage VF1, but the amplitude is the same).
[0019]
Further, the drive / control circuit 4 sends a drive signal of the switch means Q1 of the DC-DC converter circuit 1 to the c terminal so that the discharge lamp power matches the predetermined set power value. Furthermore, drive signals for the four switch means Q2 to Q5 are sent to the f, g, h, and i terminals. A drive signal for the active switch means Q6 of the flyback voltage generation circuit 33 (a signal that is turned on for a predetermined period) is sent to the j terminal. The success or failure of activation of the discharge lamp DL by the igniter circuit 3 is determined by detecting the output current of the inverter circuit 2 by the current detection resistor R2. When the discharge lamp DL is activated, the output current increases. When this is detected, the drive signal for the active switch means Q is not sent again. When the activation of the discharge lamp DL fails, the active switch means Q6 is again turned on to generate the igniter voltage VF2. When the activation failure of the discharge lamp DL reaches a predetermined number of times, the operation of the entire discharge lamp lighting device is stopped.
[0020]
Further, in order to protect the active switch means Q6, when the collector voltage detection of the active switch means Q6 by the k terminal reaches a predetermined value, an impedance element (resistor, capacitor) is connected in parallel with the capacitor C4, and the collector voltage Protective action to reduce the Although not shown in the drawings, when the collector current (or emitter current) of the active switch means Q6 is detected and reaches a predetermined value, a protective operation for immediately shutting off the active switch means Q6 may be performed. Further, when the activation of the discharge lamp DL fails and the active switch means Q6 is turned on again, the second time increases the collector current from the first time (increases the excitation energy), and increases the igniter voltage VF2 from the first time. There is a case where a voltage is used to make it easy to start the discharge lamp DL.
[0021]
The experiment of Example 1 was carried out, using an insulated gate bipolar transistor (IGBT) with 12V as the power supply voltage E, 900V withstand voltage and 180A peak current as the active switch means Q6, and using a pulse transformer T2 with a boost ratio of 30 times, the peak value An 800V flyback voltage VF1 and an igniter voltage VF2 having a peak value of 24 kV were obtained. The metal halide lamp (D2 bulb) for automobiles was connected as the discharge lamp DL, and it was confirmed that it could be started up. FIG. 5 shows a waveform of the active switch means Q6 of the first embodiment.
[0022]
FIG. 2 shows the configuration of the main circuit according to the second embodiment of the present invention. The difference from the first embodiment is that the DC voltage V3 obtained by rectifying and smoothing the AC output V2 of the inverter circuit 2 with the diode D5 and the capacitor C5 is used as the input of the igniter circuit 3. When the igniter circuit 3 is built in the socket part of the discharge lamp DL, it is sufficient to supply only the inverter circuit output V2 to the socket part, resulting in a discharge lamp lighting device without wiring in the high voltage part.
[0023]
FIG. 3 shows the configuration of the main circuit according to the third embodiment of the present invention. The difference from the first embodiment is that the DC-DC converter circuit 1 is omitted. The configuration is suitable for a case where a 42V battery is used as the DC power source E and a discharge lamp DL having a low lamp voltage (for example, 35V) is used.
[0024]
FIG. 4 shows the configuration of the main circuit according to the fourth embodiment of the present invention. The difference from the first embodiment is that the DC-DC converter circuit 1 is a boost type, and the boosted output voltage V1 of the DC-DC converter circuit 1 is used as the input of the flyback voltage generation circuit 33. Since the DC voltage V1 is higher than the DC power source E, the step-up ratio of the pulse transformer T2 can be set low.
[0025]
As the active switch means Q6 of the embodiment described above, a bipolar transistor, MOSFET, static induction transistor (SIT), etc. can be used, but an insulated gate bipolar transistor (IGBT) having features of high breakdown voltage and low saturation voltage. ) Is particularly desirable. There are many types of IGBTs with a built-in reverse diode D4, and D4 can be substantially omitted.
[0026]
Since the capacitor C4 has a capacitance of about several hundred pico F to several tens of nano F, the component shape is small. In addition, the electrostatic capacitance parasitic to the active switch means Q6 and the winding of the pulse transformer T2 has the same effect as the capacitor C4, so that C4 itself can be omitted depending on the state of implementation.
[0027]
【The invention's effect】
According to the present invention, since the igniter circuit comprises a flyback voltage generation circuit including a pulse transformer and active switch means, a high voltage diode, a large current resistant film capacitor, and a self-extinguishing switch means are used without using them. The high voltage pulse required for starting the electric lamp can be generated, and it is small and low cost. In addition, since the DC voltage of each part can be used as the input of the igniter circuit, a configuration suitable for the application is possible. Furthermore, since the igniter voltage can be varied by controlling the ON period of the active switch means, it is possible to generate a high voltage pulse at start-up suitable for various discharge lamps.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of Embodiment 1 of the present invention.
FIG. 2 is a circuit diagram of Embodiment 2 of the present invention.
FIG. 3 is a circuit diagram of Embodiment 3 of the present invention.
FIG. 4 is a circuit diagram of Embodiment 4 of the present invention.
FIG. 5 is a waveform diagram for explaining the operation of the first embodiment of the present invention.
FIG. 6 is a circuit diagram of a conventional example.
FIG. 7 is a waveform diagram for explaining the operation of a conventional example.
FIG. 8 is a characteristic diagram for explaining the operation of a conventional example.
[Explanation of symbols]
E DC power supply, DL discharge lamp, 1 DC-DC converter circuit, 2 inverter circuit, 3 igniter circuit, 33 flyback voltage generation circuit, 4 drive / control circuit, Q1 to Q5 switching means, Q6 active switching means, X1 self-extinguishing Arc type switch means, T1 transformer, T2 pulse transformer, C4 capacitor, D4 diode

Claims (5)

A DC-DC converter circuit for controlling power supplied to a discharge lamp as a load by boosting or stepping down a DC power source, and an inverter for converting the boosted or stepped down DC voltage into an AC voltage and supplying the alternating voltage to the discharge lamp as a load A discharge lamp lighting device comprising a circuit and an igniter circuit for applying a high-pressure pulse at the start of a discharge lamp as a load,
The discharge lamp lighting device, wherein the igniter circuit comprises a DC power supply as an input and constitutes a flyback voltage generation circuit including a pulse transformer and active switch means. A DC-DC converter circuit that controls the power supplied to a discharge lamp as a load by stepping up or down a DC power supply, and an inverter that converts the boosted or stepped down DC voltage into an AC voltage and supplies it to the discharge lamp as a load A discharge lamp lighting device comprising a circuit and an igniter circuit for applying a high-pressure pulse at the start of a discharge lamp as a load,
The discharge lamp lighting device according to claim 1, wherein the igniter circuit receives a DC voltage obtained by rectifying the output of the inverter circuit and constitutes a flyback voltage generation circuit including a pulse transformer and active switch means. A discharge lamp lighting device comprising: an inverter circuit that converts a DC power source into an AC voltage and supplies it to a discharge lamp that is a load; and an igniter circuit that applies a high-pressure pulse when starting the discharge lamp that is a load,
The discharge lamp lighting device characterized in that the igniter circuit forms a flyback voltage generation circuit having a pulse transformer and active switch means with the DC power supply as an input. A DC-DC converter circuit that boosts a DC power source and controls power supplied to a discharge lamp as a load; an inverter circuit that converts the boosted DC voltage into an AC voltage and supplies the AC voltage to the discharge lamp; A discharge lamp lighting device comprising an igniter circuit that applies a high-pressure pulse at the start of the discharge lamp,
The discharge lamp lighting device according to claim 1, wherein the igniter circuit forms a flyback voltage generation circuit having a pulse transformer and active switch means by receiving the boosted DC voltage. 5. The discharge lamp lighting device according to claim 1, wherein an insulated gate bipolar transistor is used as the active switch means.

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