JP4413479B2 - Discharge lamp lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp lighting device including a takeover circuit that smoothly shifts from glow discharge to arc discharge at the start of lighting of the discharge lamp.
[0002]
[Prior art]
FIG. 9 is a circuit diagram showing a conventional discharge lamp lighting device. In the figure, 1 is a DC power source, 2 is an FET, 3 is a transformer, 4 is a diode, 5 is a smoothing capacitor. Configure.
6 is a resistor, and 7 is a capacitor, and the takeover circuit is configured as described above.
Reference numerals 8a to 8d denote FETs, which constitute an inverter.
9 is an igniter and 10 is a discharge lamp.
FIG. 10 is a circuit diagram showing a conventional discharge lamp lighting device disclosed in, for example, Japanese Patent Laid-Open No. 9-283298. In the figure, 11 is a resistor, 12a and 12b are diodes, 13a and 13b are capacitors, and 14 is a resistor. It is. Other configurations are the same as those in FIG.
FIG. 11A is a waveform diagram showing each discharge current, where A is the discharge current of the smoothing capacitor 5, B is the discharge current of the capacitor 7, and C is the output current of the DC / DC converter.
FIG. 11B is a waveform diagram showing the discharge lamp current, which is a current waveform obtained by adding the above currents A to C. FIG.
[0003]
Next, the operation will be described.
In FIG. 9, in the DC / DC converter, the DC power supply 1 is switched by the FET 2 to be AC, and the voltage is boosted by the transformer 3. Further, it is rectified by the diode 4 and smoothed by the smoothing capacitor 5 to obtain a boosted direct current. At this time, the capacitor 7 of the takeover circuit is charged via the resistor 6.
At the start of lighting of the discharge lamp 10, the FETs 8 a and 8 d of the inverter are turned on, the FETs 8 b and 8 c are turned off, and a DC voltage of, for example, 400 V is applied from the DC / DC converter to the discharge lamp 10. For example, an igniter pulse of 20000 V is applied to 10.
As a result, glow discharge due to high-voltage dielectric breakdown starts between the electrodes of the discharge lamp 10, and further, the discharge lamp 10 shifts to arc discharge by supplying current to the discharge lamp 10 due to discharge of the smoothing capacitor 5 and the capacitor 7. Emits stable bright light. At this time, the DC voltage between the electrodes of the discharge lamp 10 is about 100V, for example.
FIG. 11 shows the discharge lamp current from the glow discharge to the arc discharge, and the discharge current B from the takeover circuit enables a stable transition from the glow discharge to the arc discharge.
That is, there is a concern that the discharge current A of the smoothing capacitor 5 and the output current C of the DC / DC converter alone will cause the current value at the end of glow discharge to be extremely low and cannot be transferred to arc discharge. By providing a takeover circuit consisting of 7, it is possible to prevent the current value at the end of glow discharge from being extremely reduced by the discharge current B through the resistor 6 by the capacitor 7, and stable from glow discharge to arc discharge. To be able to migrate.
If a stable arc discharge is obtained, the inverter, that is, the FETs 8 a to 8 d are switched, the direct current smoothed by the smoothing capacitor 5 is converted into alternating current, and supplied to the discharge lamp 10 to shift to normal lighting.
[0004]
In the conventional discharge lamp lighting device shown in FIG. 10, the takeover circuit is composed of resistors 11 and 14, diodes 12a and 12b, and capacitors 13a and 13b. In this way, two capacitors 13a and 13b are connected. By dividing, the capacity and voltage rating are halved.
[0005]
[Problems to be solved by the invention]
Since the conventional discharge lamp lighting device is configured as described above, the takeover circuit is constituted by a fixed resistor and a capacitor, and the discharge current by the capacitor is limited by the fixed resistor and flows.
However, if it is a fixed resistor, since the discharge from the capacitor of the takeover circuit starts simultaneously with the discharge of the smoothing capacitor at the start of lighting of the discharge lamp 10, the current suddenly increases at the start of the glow discharge, At this time, if the charge of the capacitor of the takeover circuit is used up, there is a concern that the current at the time of transition from glow discharge to arc discharge will be extremely reduced.
Therefore, in order to enable a stable transition from glow discharge to arc discharge in the conventional takeover circuit, the capacitance of the takeover circuit capacitor is increased, and the resistance value and rating of the fixed resistance of the takeover circuit are set. There were issues such as the need to increase power.
[0006]
The present invention has been made to solve the above-described problems, and is capable of supplying a suitably controlled current to the discharge lamp, and lighting the discharge lamp to reduce the capacity and size of the takeover circuit capacitor. The object is to obtain a device.
[0007]
[Means for Solving the Problems]
In the discharge lamp lighting device according to the present invention, the takeover circuit includes a first capacitor charged by the output of the DC / DC converter, and a current supplied from the first capacitor to the discharge lamp as a fixed resistor or a variable resistor. With a semiconductor switch that can be controlled arbitrarily by operating like A constant current control circuit for controlling the constant current to flow through the semiconductor switch; Is provided.
[0008]
In the discharge lamp lighting device according to the present invention, the takeover circuit is provided with a constant resistance control circuit for controlling the semiconductor switch to have a constant resistance.
[0009]
In the discharge lamp lighting device according to the present invention, the takeover circuit is provided with a constant resistance control circuit for controlling the constant current to flow through the semiconductor switch.
[0010]
In the discharge lamp lighting device according to the present invention, the takeover circuit includes a current detection circuit for detecting a current supplied from the smoothing capacitor and the first capacitor to the discharge lamp, and a current value detected by the current detection circuit is constant. And a current control circuit for controlling the current flowing through the semiconductor switch.
[0011]
In the discharge lamp lighting device according to the present invention, the take-over circuit includes a second capacitor and a resistor charged by the output of the DC / DC converter, and generates a time constant voltage due to the discharge of the second capacitor. A circuit and a current control circuit for controlling a current flowing through the semiconductor switch in accordance with a time constant voltage generated by the time constant circuit are provided.
[0012]
The discharge lamp lighting device according to the present invention has a takeover circuit, DC / DC converter A first capacitor provided between one of the main lighting power supply lines and the auxiliary power supply line and charged by a larger voltage than between the main lighting power supply lines; DC / DC converter Provided between the other of the main lighting power lines and the auxiliary power line Behaves like a fixed or variable resistor Semiconductor switch and semiconductor switch control that supplies a control signal to the semiconductor switch at an arbitrary timing when the discharge lamp starts lighting, and supplies a control signal to the semiconductor switch at an inverter operation timing when the discharge lamp is normally lit And a circuit.
[0013]
In the discharge lamp lighting device according to the present invention, the control signal permission for permitting the control signal supplied to the semiconductor switch from the semiconductor switch control circuit only when the voltage between the main lighting power supply lines is equal to or lower than the predetermined voltage in the takeover circuit. A circuit is provided.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 1 of the present invention, in which 1 is a DC power source, 2 is an FET, 3 is a transformer, 4 is a diode, 5 is a smoothing capacitor, Thus, a DC / DC converter is configured.
Reference numeral 21 denotes a capacitor (first capacitor), 22 denotes an FET (semiconductor switch), 23 denotes a parasitic diode of the FET 22, and 24 denotes a variable power supply. Thus, a takeover circuit is configured.
Reference numerals 8a to 8d denote FETs, which constitute an inverter.
9 is an igniter and 10 is a discharge lamp.
FIG. 2 is a waveform diagram showing the discharge lamp voltage and the discharge lamp current.
[0015]
Next, the operation will be described.
In FIG. 1, in the DC / DC converter, the DC power source 1 is switched by the FET 2 to be AC, and the voltage is boosted by the transformer 3. Further, it is rectified by the diode 4 and smoothed by the smoothing capacitor 5 to obtain a boosted direct current. At this time, the capacitor 21 of the takeover circuit is charged via the parasitic diode 23 of the FET 22.
At the start of lighting of the discharge lamp 10, the FETs 8a and 8d of the inverter are turned on, the FETs 8b and 8c are turned off, and a DC voltage of 400 V, for example, is applied from the DC / DC converter to the discharge lamp 10 as shown in FIG. , And an igniter pulse of 20000 V, for example, is applied from the igniter 9 to the discharge lamp 10.
As a result, as shown in FIG. 2B, glow discharge due to high-voltage breakdown begins between the electrodes of the discharge lamp 10, and further, the discharge to the discharge lamp 10 due to discharge of the smoothing capacitor 5 and the capacitor 21 of the takeover circuit. When the electric current is supplied, an arc discharge is performed, and the discharge lamp 10 emits stable bright light. At this time, the DC voltage between the electrodes of the discharge lamp 10 is about 100V, for example.
Here, in the first embodiment, the takeover circuit is configured by the capacitor 21, the FET 22, and the variable power source 24. By controlling the voltage applied from the variable power source 24 to the gate of the FET 22, the capacitor 21 to the FET 22 are controlled. The current supplied to the discharge lamp 10 through the drain and source can be arbitrarily controlled.
That is, there is a concern that the current value at the end of the glow discharge is extremely reduced by only the discharge current of the smoothing capacitor 5 and the output current of the DC / DC converter, and it is not possible to shift to the arc discharge. By providing a takeover circuit composed of the power supply 24, the current supplied from the capacitor 21 to the discharge lamp 10 through the FET 22 is arbitrarily controlled by voltage control of the variable power supply 24, and the discharge current at the end of glow discharge is controlled by the discharge current. It is possible to prevent the current value from being extremely lowered and to make a stable transition from glow discharge to arc discharge.
If a stable arc discharge is obtained, the inverter, that is, the FETs 8 a to 8 d are switched, the direct current smoothed by the smoothing capacitor 5 is converted into alternating current, and supplied to the discharge lamp 10 to shift to normal lighting.
[0016]
As described above, according to the first embodiment, the takeover circuit is configured by the capacitor 21, the FET 22, and the variable power source 24, and thus the voltage applied from the variable power source 24 to the gate of the FET 22 is controlled. The current supplied from 21 to the discharge lamp 10 through the FET 22 can be arbitrarily controlled.
Therefore, the capacity of the capacitor 21 of the takeover circuit can be reduced and reduced in size.
In addition, since an appropriately controlled current can be supplied to the discharge lamp 10, it is not necessary to charge the capacitor 21 at a high voltage and store a large amount of electrostatic energy, so that the DC / DC converter and the smoothing capacitor 5, The capacitor 21 can be reduced in voltage rating and size.
Furthermore, an excessive inrush current immediately after lighting can be suppressed, and scattering of the electrodes of the discharge lamp 10 can be reduced, and the life of the discharge lamp 10 can be extended.
[0017]
In FIG. 1, the takeover circuit is constituted by the capacitor 21, the FET 22, and the variable power source 24. However, if a fixed power source (constant resistance control circuit) that generates a constant voltage is provided instead of the variable power source 24, the FET 22 is provided. It is possible to perform a constant resistance operation between the drain and the source.
Therefore, if an appropriate radiator material is used for an FET having a high heat radiation effect, a conventional large power resistor can be replaced with a small package.
[0018]
Embodiment 2. FIG.
FIG. 3 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 2 of the present invention, in which 31 is a fixed power source (constant current control circuit), 32 is a resistor (constant current control circuit), and capacitor 21 And a takeover circuit together with the FET 22. Other configurations are the same as those in FIG.
[0019]
Next, the operation will be described.
As shown in FIG. 3, by connecting a resistor 32 to the source of the FET 22 and applying a constant voltage to the gate of the FET 22, a constant current operation can be performed between the drain and the source of the FET 22.
Therefore, with respect to the low discharge lamp voltage immediately after starting lighting, the charge of the capacitor 21 is preserved without flowing a large current from the takeover circuit side, and the discharge lamp 10 having a high voltage recovered by energization is A minimum current required for takeover can be ensured, and an appropriate small capacitor 21 can be used without using a large capacitor 21 that satisfies all of the various conditions.
[0020]
Embodiment 3 FIG.
FIG. 4 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 3 of the present invention. In the figure, 41 is a current detection resistor (current detection circuit), 42 is a fixed power supply (current control circuit), and 43 is an operational amplifier. (Current control circuit) and constitutes a takeover circuit together with the capacitor 21 and the FET 22. Other configurations are the same as those in FIG.
[0021]
Next, the operation will be described.
As shown in FIG. 4, the current from the smoothing capacitor 5 to the discharge lamp 10 that flows uncontrolled immediately after the start of lighting, and the current to the discharge lamp 10 that is arbitrarily controlled by the FET 22 from the capacitor 21 in the takeover circuit. Is added to the negative terminal of the operational amplifier 43 as a voltage signal. A predetermined constant voltage is input from the fixed power source 42 to the plus terminal of the operational amplifier 43, and the FET 22 is operated according to the difference voltage between them. As a result, the current flowing through the FET 22 can be controlled so that the current value detected by the current detection resistor 41 is constant.
Accordingly, it is possible to output a current only from the smoothing capacitor 5 immediately after lighting, and to output a current from the capacitor 21 when the current from the smoothing capacitor 5 decreases, and to output a continuous and sufficient current.
[0022]
Embodiment 4 FIG.
5 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 4 of the present invention, in which 51 is a diode (time constant circuit), 52 is a capacitor (second capacitor, time constant circuit), and 53 is It is a resistor (time constant circuit) and constitutes a takeover circuit together with the capacitor 21, FET 22 and operational amplifier 43. Other configurations are the same as those in FIG.
[0023]
Next, the operation will be described.
As shown in FIG. 5, when the smoothing capacitor 5 is charged by the output of the DC / DC converter, the capacitor 52 is also charged via the diode 51.
Along with the discharge of the smoothing capacitor 5 immediately after the start of lighting, the capacitor 52 is also discharged. At this time, the voltage signal output to the negative terminal of the operational amplifier 43 corresponds to the time constant of the capacitor 52 and the resistor 53. .
Further, the voltage of the capacitor 21 is output to the plus terminal of the operational amplifier 43. As a result, the operational amplifier 43 has a voltage change of the capacitor 21 equivalent to a voltage change corresponding to the time constant of the capacitor 52 and the resistor 53. The FET 22 is controlled so that
Therefore, the current flowing through the FET 22 can be arbitrarily controlled by arbitrarily setting the time constants of the capacitor 52 and the resistor 53, and a continuous and excessive current can be output.
[0024]
Embodiment 5 FIG.
FIG. 6 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 5 of the present invention, in which 61 is a transformer, 62 and 63 are diodes, DC power supply 1, FET 2, diode 4, and smoothing capacitor 5 In addition, a DC / DC converter is configured.
Reference numeral 64 is a high-voltage main lighting power line, 65 is a low-voltage main lighting power line, and 66 is an auxiliary power line.
67 is a capacitor (first capacitor), 68 is an FET (semiconductor switch), 69 is a capacitor, 70 is a resistor, 71 is a diode, and 72 is a resistor. 73 is an FET control circuit (semiconductor switch control circuit) that supplies a control voltage to the FET 68 at an arbitrary timing at the start of lighting, and supplies a control voltage to the FET 68 at an operation timing of the inverters (FETs 8a to 8d) at the time of normal lighting. Thus, the takeover circuit is configured as described above.
FIG. 7 is a waveform diagram showing the discharge lamp voltage and the FET control voltage.
[0025]
Next, the operation will be described.
In FIG. 6, the secondary side of the transformer 61 is composed of three lines: a high voltage main lighting power line 64, a low voltage main lighting power line 65, and an auxiliary power line 66. In the DC / DC converter, rectification is performed by diodes 4, 62, 63. At the same time, it is smoothed by the smoothing capacitor 5 to obtain a boosted direct current. At this time, the smoothing capacitor 5 is charged with, for example, 200V, and the capacitor 67 of the takeover circuit is charged with, for example, 400V, which is larger than that.
At the start of lighting of the discharge lamp 10, as shown in FIG. 7B, a control voltage is supplied from the FET control circuit 73 to the FET 68 at an arbitrary timing. As a result, the FET 68 operates, and the capacitor 69, the resistor 70, and the diode 71 act to start the discharge of the smoothing capacitor 5 and the discharge of the capacitor 61 of the takeover circuit. Can be prevented from being extremely lowered, and a stable transition from glow discharge to arc discharge can be achieved.
Thus, when the discharge lamp 10 is turned on, a sufficient current necessary for takeover can be supplied from the capacitor 67 charged with a large voltage.
If a stable arc discharge is obtained, the inverter, that is, the FETs 8 a to 8 d are switched, the direct current smoothed by the smoothing capacitor 5 is converted into alternating current, and supplied to the discharge lamp 10 to shift to normal lighting. . At this time, as shown in FIG. 7B, a control voltage is supplied from the FET control circuit 73 to the FET 68 at the operation timing of the inverter.
As a result, when the discharge lamp 10 is normally lit, the alternating current supplied from the inverter to the discharge lamp 10 can be steep to stabilize the discharge of the discharge lamp 10.
[0026]
As described above, according to the fifth embodiment, when the discharge lamp 10 is turned on, a sufficient current necessary for takeover can be supplied from the capacitor 67 charged with a large voltage. Further, when the discharge lamp 10 is normally lit, the alternating current supplied from the inverter to the discharge lamp 10 can be made steep to stabilize the discharge of the discharge lamp.
Note that Japanese Patent Application No. 2001-332256 is a prior document related to the technique of the fifth embodiment.
[0027]
Embodiment 6 FIG.
FIG. 8 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 6 of the present invention. In the figure, 81 is an operational amplifier, 82 is an AND gate, and the control signal from the FET control circuit 73 is permitted as described above. A control signal permission circuit is configured. Other configurations are the same as those in FIG.
[0028]
Next, the operation will be described.
In FIG. 8, when the discharge lamp 10 is turned on, for example, 0V is applied to the high-voltage main lighting power line 64, −200V is applied to the low-voltage main lighting power line 65, and −400V is applied to the auxiliary power line 66. When the FET 68 is turned on, a maximum of 400V is applied to the inverters (FETs 8a to 8d), and it is necessary to provide a rated voltage of the inverter of, for example, 450V, resulting in an increase in size.
In the sixth embodiment, for example, -150V is compared with the voltage of the low-voltage main lighting power line 65, and when the voltage of the low-voltage main lighting power line 65 becomes higher than -150V, the control from the FET control circuit 73 is performed. An operational amplifier 81 and an AND gate 82 that allow signals are provided.
As a result, when the discharge lamp 10 starts to discharge and the discharge lamp voltage decreases, the FET 68 is operated, and a maximum of about 200 V is applied to the diode 63 and the inverters (FETs 8a to 8d). It is only necessary to provide an inverter with a rated voltage of, for example, 250 V, and the size can be reduced.
[0029]
【The invention's effect】
As described above, according to the present invention, the takeover circuit is configured such that the first capacitor charged by the output of the DC / DC converter and the current supplied from the first capacitor to the discharge lamp are fixed resistance or variable. A semiconductor switch that operates like a resistor and can be controlled arbitrarily A constant current control circuit for controlling the constant current to flow through the semiconductor switch; Therefore, a suitably controlled current can be supplied to the discharge lamp, and the first capacitor can be reduced in capacity and size. Moreover, since it is not necessary to apply a high voltage to the smoothing capacitor and the first capacitor by the DC / DC converter, the DC / DC converter / smoothing capacitor or / and the first capacitor can be reduced in voltage rating and size. There is.
[0030]
According to the present invention, since the takeover circuit is configured to include the constant resistance control circuit that controls the semiconductor switch to have a constant resistance, the operation equivalent to that of the conventional takeover circuit can be performed. Further, if the heat dissipation effect of the semiconductor switch is enhanced, there is an effect that a conventional large power resistor can be replaced with a small semiconductor.
[0031]
According to the present invention, the takeover circuit is configured to include the constant resistance control circuit for controlling the constant current to flow through the semiconductor switch. Therefore, the minimum current required during the takeover can be ensured. There is an effect that an appropriate small first capacitor can be used without using a large first capacitor that satisfies all of the conditions.
[0032]
According to the present invention, in the takeover circuit, the current detection circuit for detecting the current supplied from the smoothing capacitor and the first capacitor to the discharge lamp, and the current value detected by the current detection circuit are made constant. And a current control circuit for controlling the current flowing through the semiconductor switch, so that the current is output only from the smoothing capacitor immediately after lighting, and the current is output from the first capacitor when the current from the smoothing capacitor decreases. There is an effect that a continuous and excessive current can be output.
[0033]
According to the present invention, the take-over circuit includes a second capacitor and a resistor charged by the output of the DC / DC converter, and generates a time constant voltage by discharging the second capacitor. And a current control circuit that controls the current flowing through the semiconductor switch in accordance with the time constant voltage generated by the constant circuit, so that the current flowing through the semiconductor switch can be arbitrarily controlled by any setting of the time constant circuit. Therefore, it is possible to output a continuous current without excess or deficiency.
[0034]
According to the present invention, in the takeover circuit, DC / DC converter A first capacitor provided between one of the main lighting power supply lines and the auxiliary power supply line and charged by a larger voltage than between the main lighting power supply lines; DC / DC converter Provided between the other of the main lighting power lines and the auxiliary power line Behaves like a fixed or variable resistor Semiconductor switch and a semiconductor switch control circuit that supplies a control signal to the semiconductor switch at an arbitrary timing when the discharge lamp starts lighting and supplies a control signal to the semiconductor switch at an inverter operation timing when the discharge lamp is normally lit Therefore, when the discharge lamp is turned on, a sufficient current necessary for takeover can be supplied from the first capacitor charged with a large voltage. Further, during normal lighting of the discharge lamp, the alternating current supplied from the inverter to the discharge lamp can be made steep to stabilize the discharge of the discharge lamp. There is an effect that these functions can be shared by the semiconductor switch and the semiconductor switch control circuit.
[0035]
According to the present invention, the takeover circuit includes the control signal permission circuit that permits the control signal supplied from the semiconductor switch control circuit to the semiconductor switch only when the voltage between the main lighting power supply lines is equal to or lower than the predetermined voltage. Thus, the withstand voltage of the inverter can be reduced according to the predetermined voltage, and the inverter can be downsized.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 1 of the present invention.
FIG. 2 is a waveform diagram showing a discharge lamp voltage and a discharge lamp current.
FIG. 3 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 2 of the present invention.
FIG. 4 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 3 of the present invention.
FIG. 5 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 4 of the present invention.
FIG. 6 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 5 of the present invention.
FIG. 7 is a waveform diagram showing a discharge lamp voltage and an FET control voltage.
FIG. 8 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 6 of the present invention.
FIG. 9 is a circuit diagram showing a conventional discharge lamp lighting device.
FIG. 10 is a circuit diagram showing a conventional discharge lamp lighting device.
FIG. 11 is a waveform diagram showing a discharge lamp current.
[Explanation of symbols]
1 DC power supply, 2,8a to 8d FET, 3,61 transformer, 4,62,63,71 diode, 5 smoothing capacitor, 9 igniter, 10 discharge lamp, 21,67 capacitor (first capacitor), 22,68 FET (semiconductor switch), 23 parasitic diode, 24 variable power supply, 31 fixed power supply (constant current control circuit), 32 resistor (constant current control circuit), 41 current detection resistor (current detection circuit), 42 fixed power supply (current control) Circuit), 43 operational amplifier (current control circuit), 51 diode (time constant circuit), 52 capacitor (second capacitor, time constant circuit), 53 resistor (time constant circuit), 64 high voltage main lighting power line, 65 low voltage main Lighting power line, 66 auxiliary power line, 69 capacitor, 70, 72 resistance, 73 FET control circuit (semiconductor switch control circuit), 81 ampere Flop 82 and gate.

Claims (6)

A smoothing capacitor provided in a DC / DC converter that boosts the voltage of the DC power supply;
In a discharge lamp lighting device comprising a takeover circuit for supplying a current to the discharge lamp together with the smoothing capacitor at the start of lighting of the discharge lamp and shifting the discharge lamp from glow discharge to arc discharge,
The takeover circuit
A first capacitor charged by the output of the DC / DC converter;
A semiconductor switch capable of arbitrary control by operating the current supplied from the first capacitor to the discharge lamp as a fixed resistor or a variable resistor ;
A constant current control circuit for controlling the constant current to flow through the semiconductor switch;
A discharge lamp lighting device comprising: A smoothing capacitor provided in a DC / DC converter that boosts the voltage of the DC power supply;
In a discharge lamp lighting device comprising a takeover circuit for supplying a current to the discharge lamp together with the smoothing capacitor at the start of lighting of the discharge lamp and shifting the discharge lamp from glow discharge to arc discharge,
The takeover circuit
A first capacitor charged by the output of the DC / DC converter;
A semiconductor switch capable of arbitrary control by operating the current supplied from the first capacitor to the discharge lamp as a fixed resistor or a variable resistor;
A current detection circuit for detecting a current supplied to the discharge lamp from said smoothing capacitor and the first capacitor,
Lamp lighting device release characterized by comprising a current control circuit for controlling the current flowing through the semiconductor switch so that the current value detected by the current detecting circuit is constant. A smoothing capacitor provided in a DC / DC converter that boosts the voltage of the DC power supply;
In a discharge lamp lighting device comprising a takeover circuit for supplying a current to the discharge lamp together with the smoothing capacitor at the start of lighting of the discharge lamp and shifting the discharge lamp from glow discharge to arc discharge,
The takeover circuit
A first capacitor charged by the output of the DC / DC converter;
A semiconductor switch capable of arbitrary control by operating the current supplied from the first capacitor to the discharge lamp as a fixed resistor or a variable resistor;
A time constant circuit comprising a second capacitor and a resistor charged by the output of the DC / DC converter, and generating a time constant voltage by discharging the second capacitor;
The time-release lamp lighting device you characterized by comprising a current control circuit for controlling a current flowing through the semiconductor switch in accordance with the constant voltage when it is generated by the time constant circuit. A smoothing capacitor provided between the main lighting power lines of the DC / DC converter;
An inverter that is provided between the main lighting power lines, converts the direct current smoothed by the smoothing capacitor during normal lighting of the discharge lamp into alternating current, and supplies the alternating current to the discharge lamp;
In a discharge lamp lighting device comprising a takeover circuit for supplying a current to the discharge lamp together with the smoothing capacitor at the start of lighting of the discharge lamp and shifting the discharge lamp from glow discharge to arc discharge,
The takeover circuit
A first capacitor provided between one of the main lighting power supply lines of the DC / DC converter and the auxiliary power supply line and charged by a voltage larger than that between the main lighting power supply lines;
A semiconductor switch provided between the other of the main lighting power lines of the DC / DC converter and the auxiliary power line, and operating like a fixed resistor or a variable resistor ;
A semiconductor switch control circuit for supplying a control signal to the semiconductor switch at an arbitrary timing when the discharge lamp starts lighting, and for supplying a control signal to the semiconductor switch at an operation timing of the inverter when the discharge lamp is normally lit; A discharge lamp lighting device comprising:   The takeover circuit includes a control signal permission circuit that permits a control signal supplied from the semiconductor switch control circuit to the semiconductor switch only when the voltage between the main lighting power supply lines is equal to or lower than a predetermined voltage. Item 5. A discharge lamp lighting device according to Item 4. A DC / DC converter that boosts the voltage of a DC power source and supplies a current smoothed by a smoothing capacitor to a discharge lamp;
In a discharge lamp lighting device comprising a takeover circuit for supplying a current to the discharge lamp together with the smoothing capacitor and shifting the discharge lamp from glow discharge to arc discharge,
The takeover circuit
A first capacitor charged by the output of the DC / DC converter;
A semiconductor switch for controlling a current supplied from the first capacitor to the discharge lamp;
A control circuit that controls the current supplied from the first capacitor to the discharge lamp by controlling the semiconductor switch based on a comparison result between the voltage of the first capacitor and a target value that changes with time. A discharge lamp lighting device comprising:

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