JP4724909B2 - HID lamp lighting circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a HID lamp lighting circuit for lighting HID lamps such as metal halide lamps used for lighting indoor commercial facilities such as stores and outdoor facilities, light sources for liquid crystal projectors, automobile headlights, and the like.
[0002]
[Prior art]
HID lamps (High Intensity Discharge Lamps) are also called high-intensity discharge lamps or high-pressure discharge lamps. They not only excel in luminous efficiency with respect to power consumption, but also have less heat generation for the same light intensity than halogen lamps, etc. In recent years, it has been used where a high-intensity light source is required such as lighting for indoor commercial facilities and outdoor facilities.
[0003]
The HID lamp starts discharging by applying a high voltage of several kV at the start, and thereafter self-sustained by applying a relatively low lamp voltage of several tens to several hundreds V, and gradually The voltage increases and the HID lamp is turned on.
[0004]
FIG. 9 shows a general lighting circuit 41 for lighting such an HID lamp with an AC rectangular wave pulse. The main circuit 2 applies a lamp voltage of several tens to several hundreds V to the HID lamp 1, and several kV. A starting circuit 3 for applying a high starting voltage is provided.
[0005]
The main circuit 2 includes a rectifier circuit 5 for full-wave rectification of a sinusoidal AC wave supplied from an AC power supply 4, a power factor improvement circuit 6 for converting the rectified pulsating voltage into a DC smoothed voltage, and the DC smoothed voltage as a predetermined value. A power control circuit 8 comprising a chopper circuit 7A for converting to a rectangular pulse having a pulse width, a smoothing circuit 7B for smoothing the rectangular pulse again to obtain a DC lamp voltage corresponding to the target lamp power, and the obtained DC lamp voltage An inverter 9 for converting the same voltage into an alternating current rectangular wave voltage is provided, and the inverter 9 is connected to the HID lamp 1 via the starting circuit 3.
[0006]
The starting circuit 3 includes a step-up transformer (not shown), and when a lighting switch (not shown) of the HID lamp 1 is turned on, a high voltage of several kV is started so as to start discharge between the electrodes of the HID lamp 1. Generate a starting voltage.
[0007]
According to this lighting circuit 41, when a lighting switch (not shown) is turned on, a starting voltage of several kV is applied from the starting circuit 3 to the HID lamp 1 to start discharging, and after starting discharging, the main circuit 2 By applying a comparatively low lamp voltage of several tens to several hundreds V supplied from the self-sustained discharge, the lamp voltage gradually increases and the HID lamp is turned on.
[0008]
[Problems to be solved by the invention]
By the way, in the HID lamp 1, after the discharge is started, the temperature in the lamp gradually increases and the vapor pressure reaches a steady value to obtain a necessary amount of light, but it takes several minutes.
Here, when the lamp voltage is applied so that the rated power consumption is reached immediately after the start of discharge, there is a problem that the electrodes are damaged and the product life of the HID lamp 1 is shortened.
[0009]
In recent years, the lighting circuit 41 of the HID lamp 1 has been configured to meet the demand for miniaturization by configuring a control circuit using a hybrid IC and improving its mounting density.
However, the design of the control circuit using hybrid IC is not only difficult to change, but also the design differs depending on the type of HID lamp such as high-pressure mercury lamp, metal halide lamp, high-pressure sodium lamp and the rated power. There was a problem that it could not be shared and the manufacturing cost increased.
[0010]
There has also been proposed a control circuit that is reduced in size by computer and the power is PWM controlled.
However, the PWM control has a drawback that the resolution of the pulse width is stepwise, and it is difficult to control the lamp power to an arbitrary value.
Further, when the control circuit is made into a computer and the lighting circuit is downsized, if the internal circuit generates heat, the life of the electronic component is significantly reduced. The main cause of this heat generation is the switching loss of the chopper circuit 7A, but if a fan for forced cooling or the like is provided in the lighting circuit 41, it becomes difficult to reduce the size.
[0011]
Therefore, the present invention can turn on the HID lamp without damaging the electrode immediately after the start of discharge, and can control the lamp power with a finer precision than the clock frequency of the computer when the lamp power is variably controlled by PWM control. Furthermore, it is a technical problem to suppress heat generation due to switching loss of the chopper circuit without providing a cooling fan or the like.
[0012]
[Means for Solving the Problems]
In order to solve this problem, the present invention applies a high-voltage starting voltage supplied from a starting circuit to an HID lamp to start discharge, and then a low-pressure lamp corresponding to the lamp power supplied from the main circuit. In the lighting circuit of the HID lamp that applies a voltage and performs self-sustained discharge,
A lamp power control circuit including a switching element for converting the input DC smoothed voltage into a DC pulse voltage and outputting the target lamp power is formed in the main circuit,
After starting the discharge of the HID lamp and before supplying the lamp power of the rated operating power, the lamp power is lower than the rated operating power and the lighting starting power capable of self-sustaining discharge is suppressed, and the internal vapor pressure of the HID lamp is predetermined. When the value reaches the value, the lighting start control means for outputting a power control pulse signal to the switching element so as to gradually increase the lamp power to the rated operating power, and during the self-sustained discharge, to the switching element On the other hand, the pulse width of the power control pulse signal is set to one clock pulse so that the time average of the lamp power that varies according to the pulse width of the power control pulse signal that is output matches the preset target lamp power. The lamp power control means for increasing / decreasing the length of the input power control pulse signal to the power factor correction circuit connected to the input side of the lamp power control circuit. And an input voltage control means for variably controlling the DC smoothed voltage input from the power factor correction circuit to the lamp power control circuit according to the output voltage of the lamp power control circuit. And
[0013]
According to the present invention, after a high-voltage starting voltage is applied to the HID lamp to start discharge, the lamp voltage corresponding to the lighting start power is applied before applying the lamp voltage corresponding to the rated operating power.
This lighting start power can maintain the self-sustained discharge of the HID lamp and is set to about 1/5 of the rated power consumption, so there is little electrode damage, and therefore the product life of the HID lamp is extended. .
Next, when the internal vapor pressure of the HID lamp reaches a predetermined value, the lamp power supplied to the lamp is increased to the rated usage power, and the necessary light amount is obtained at this point, so that the necessary light amount is reached. The time will not be so slow.
[0014]
Further, the power control is performed so that the time average of the lamp power, which varies according to the pulse width of the power control pulse signal output to the switching element of the lamp power control circuit, matches the preset target lamp power. The pulse width of the pulse signal is increased or decreased by the length of one clock pulse.
Therefore, even when the pulse width of the power control pulse signal for outputting appropriate power needs to be controlled in a time unit of less than one clock pulse, the time average of the calculated lamp power is compared with the target lamp power. Therefore, the difference for one clock pulse is averaged, and the power can be controlled in units of time shorter than the time for one clock pulse.
[0015]
Furthermore, by controlling the DC smoothing voltage input from the power factor correction circuit to the lamp power control circuit according to the output voltage value, the voltage drop rate of the lamp power control circuit is maintained within an excellent range of conversion efficiency. Therefore, power loss in the lamp power control circuit can be reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a block diagram showing the overall configuration of an HID lamp lighting circuit according to the present invention, FIG. 2 is a circuit diagram showing a power factor correction circuit, FIG. 3 is a circuit diagram showing a lamp power control circuit, and FIG. 4 is a lighting start control. 5 is a flowchart showing the processing procedure of the lamp power control means, FIG. 6 is a flowchart showing the processing procedure of the input voltage control means, FIG. 7 is a signal waveform diagram in the power factor correction circuit, and FIG. Is a graph showing a change in lamp voltage at the start of lighting.
[0017]
The lighting circuit S shown in FIG. 1 includes a power supply circuit E that lights up the HID lamp 1 and a control unit C that controls the power supply circuit E. The power supply circuit E is several tens to several hundreds with respect to the HID lamp 1. A main circuit 2 for applying a relatively low rated voltage of V and a starting circuit 3 for applying a high starting voltage of several kV are provided.
[0018]
The main circuit 2 includes a rectifier circuit 5 for full-wave rectification of a sinusoidal AC voltage supplied from the AC power supply 4, and a full-wave rectified pulsating voltage V _1. DC smoothing voltage V ₂ Power factor improving circuit 6 for converting to a DC smoothing voltage V ₂ Is converted into a rectangular pulse having a predetermined pulse width to control the supplied power, and the rectangular pulse is smoothed again and the preset DC lamp voltage V _{3 is} smoothed. A lamp power control circuit 8 comprising a smoothing circuit 7B and the obtained DC lamp voltage V ₃ AC rectangular wave voltage V _{4 of the} same potential as this A full-bridge type inverter 9 for conversion into the HID lamp 1 is connected to the HID lamp 1 via the starting circuit 3.
[0019]
As shown in FIG. 2, the power factor correction circuit 6 has a pulsating voltage V ₁ that is full-wave rectified by the rectifier circuit 5. DC smoothing voltage V ₂ It is formed by a step-up / step-down converter using a switching regulator.
In this power factor correction circuit 6, a FET (field effect transistor) 10A, a coil 11, and a diode 12 are connected in series on the + side, and a diode 13, FET 10B, and a capacitor 14 are connected in parallel between the + side and the-side. The drivers 10a and 10b of the FETs 10A and 10B are connected to the control unit C via the PWM control circuit 15.
[0020]
The lamp power control circuit 8 is a DC smoothing voltage V ₂ input from the power factor correction circuit 6. At the front stage of the chopper circuit 7A converts the rectangular-pulse-wave having a predetermined pulse width, which is intended to output a DC lamp voltage V ₃ which is preset by smoothed by subsequent smoothing circuit 7B.
[0021]
Specifically, as shown in FIG. 3, an FET (field effect) serving as a switching element disposed in the chopper circuit 7A by a power control pulse signal supplied from the PWM control circuit 15 of the control unit C via the driver 16a. by turning on and off the transistor) 16, the target lamp to output a rectangular pulse having a pulse width corresponding to the voltage value V _L, by smoothing by the smoothing circuit 7B so, the target lamp voltage value V _L equal lamp voltage V ₃ Is output.
[0022]
The control unit C is composed of a single chip microcomputer 17 or the like, and on the input side thereof, a sensor 18 for detecting the input voltage of the power factor correction circuit 6, the input voltage, the output voltage and the output current of the lamp power control circuit 8, respectively. , 19, 20a, 20b are connected via an A / D converter, and FETs 10A, 10B, 16 of the power factor correction circuit 6 and the lamp power control circuit 8 are connected via the PWM control circuit 15 to the output side thereof. In addition, the starting circuit 3 and the inverter 9 are connected via the I / O port.
[0023]
A communication computer 21 controls the lighting circuit S based on a control signal transmitted from an external device (not shown), and transmits various control data of the lighting circuit S to a host computer or the like. At this time, a signal is relayed between the external device and the control unit C in correspondence with a complicated communication protocol.
As a result, the data processing burden on the control unit C can be reduced and the lighting circuit S can be reliably controlled.
[0024]
FIG. 4 is a flowchart showing the processing procedure of the lighting start control means in the controller C.
First, in step STP1, the process waits until a high voltage is applied by the starting circuit 3 and discharge is started, and when the start of discharge is confirmed, the process proceeds to step STP2.
Here, when the discharge is not started, the HID lamp 1 is in a non-conductive state, so the lamp current is 0. However, since the current flows when the discharge is started, the discharge is started by detecting this by the sensor 20b. Confirm.
[0025]
In step STP2, the lamp power W ₃ lower than the rated power consumption W _R, and outputs a power control pulse signal to the lamp power control circuit 8 so as to suppress the self-sustaining dischargeable lighting start power W _S, lighting the lamp voltage V ₃ corresponding to the start power W _S is applied to maintain the self-sustaining discharge of the HID lamp 1.
Thereby, the damage received on the electrode of the HID lamp 1 is reduced.
[0026]
Then, the processing proceeds to step STP3, the lamp voltage V ₃ and the lamp current I ₃ that is detected by the sensor 20a and 20b, on the basis of the application time, calculates the amount of heat supplied to the HID lamp 1, previously in step STP4 It is determined whether or not the set amount of heat has been reached.
Then, upon reaching a predetermined amount of heat, the process proceeds to step STP5 it is determined that the internal vapor pressure of the HID lamp 1 has reached a predetermined value, the lamp power W ₃ is increased, the lamp voltage V Accordingly ₃ is raised.
[0027]
Then, at step STP6 after lamp power W ₃ is judged to have reached to the rated power consumption W _R, the process proceeds to step STP7, the sensor 20a and a lamp voltage V ₃ is detected by and 20b lamp current I ₃ lamp power calculated, so as to maintain the rated power consumption, so as to control the lamp voltage V _3.
[0028]
FIG. 5 is a flowchart showing the processing procedure of the lamp power control means in the controller C.
First, in step STP11, a target lamp voltage value V _L is calculated based on the target lamp power and the lamp current I ₃ detected by the sensor 20b, and the pulse width of the power control pulse signal output from the PWM control circuit 15 is set as the target. It is set by the number of clock pulses of the control unit C corresponding to the lamp voltage value _VL .
As the target lamp power, normally, the rated operating power of the HID lamp 1 is used.
Next, in step STP12, the power control pulse signal is output to the lamp power control circuit 8, and at the same time, time measurement is started.
[0029]
In step STP13, to calculate the power consumption from the start of time measurement based on the lamp voltage V ₃ and the lamp current I ₃ that is detected by the sensor 20a and 20b, obtained by the product of the target lamp power and time step STP14 When these values match with the target power amount, the process returns to step STP12 without changing the pulse width of the power control pulse signal.
When the power consumption is large, the process proceeds to step STP15, the pulse width of the power control pulse signal is narrowed by one clock pulse and output to the lamp power control circuit 8, and then the process returns to step STP13.
Further, when the power consumption is small, the process proceeds to step STP16, the pulse width of the power control pulse signal is widened by one clock pulse and output to the lamp power control circuit 8, and then the process returns to step STP13.
[0030]
In this way, the amount of power consumed since the start of timing is compared with the target amount of power at the same time, and the clock pulses are increased or decreased one by one. , Control is performed so as to coincide with a preset target lamp power.
Further, since control is performed based on the average value of the detected electric energy, one clock pulse is averaged, and the power can be controlled in a unit of time shorter than the time of one clock pulse.
[0031]
FIG. 6 is a flowchart showing the processing procedure of the input voltage control means in the control unit C, and FIG. 7 is a waveform diagram showing the output input voltage control pulse signal.
This input voltage control means suppresses the heat generation of the lighting circuit S caused by the switching loss of the chopper circuit 7A.
[0032]
To do this, by setting the voltage value of the DC smoothed voltage V ₂ inputted from the power factor improving circuit 6 for chopper circuit 7A to be lower, but it is better to close to the lamp voltage V _3, too close to the HID lamp 1 since variation of the lamp voltage V ₃ applied is narrow, resulting in a case where the control is difficult.
[0033]
Therefore, in this example, in accordance with the variation of the lamp voltage _{V 3,} as the DC smoothed voltage _{V 2} is maintained at 1.1 to 2.0 times the lamp voltage _{V 3,} variably controlling the DC smoothed voltage _{V 2} It was decided to.
[0034]
First, in step STP21, the lamp voltage _{V 3} is detected by the sensor 20a, and calculates the target DC smoothed voltage $ _{V 2} by 1.1 to 2.0 times this in step STP22.
In step STP23, the pulsating voltage V ₁ that is full-wave rectified by the rectifier circuit 5 by the sensors 18 and 19 is used. And the DC smoothed voltage V ₂ output from the power factor correction circuit 6. Is detected, and the flow proceeds to step STP24, where the pulsating voltage V ₁ is detected. And DC smoothing voltage V ₂ Compare
[0035]
And the pulsating voltage V ₁ = <DC smoothing voltage V ₂ , the process proceeds to step STP25 to maintain the FET 10A of the power factor correction circuit 6 in the conductive state, and to output the control pulse signal P _B to the FET 10B, and the pulsating voltage V ₁ The boosting to target DC smoothed voltage $ V _2.
In this example, the control pulse signal _P high-level time of _B (conduction time of FET10B) _{T B,}
T _B = Kb × L
_{Kb = β ($ V 2 -V} 2) β is a proportional constant L: the inductance of the coil 11, and the low-level time (non-conduction time of FET10B) and 0.5 to 1.0 × _{T B.}
[0036]
On the other hand, the pulsation voltage V ₁ > If the DC smoothed voltage _{V 2,} the process proceeds to step STP26, while maintaining FET10B non-conductive, and outputs a control pulse signal _{P A} to FET 10a, pulsating voltages _{V 1} The steps down to the target DC smoothed voltage $ V _2.
In this example, the _{T A} (conduction time of FET 10a) high-level time of the control pulse signal _{P A,}
T _A = (Ka × L × V ₁ ) / (V ₁ −V ₂ )
_{Ka = α ($ V 2 -V} 2) α is a proportionality constant, and the low-level time (non-conduction time of the FET 10a) and 0.2 to 2.0 × _{T A.}
[0037]
Then, repeating the process of step STP23~26 until the processing of the half-wave of the pulsating voltage V ₁ is completed at step STP27, when the processing of the half-wave has been completed returns to step STP21.
[0038]
Next, the operation of the present invention will be described. When a start switch (not shown) is turned on and a start voltage is applied from the start circuit 3 and discharge of the HID lamp 1 is started, the controller C starts the lighting start control process. It is performed, as shown in FIG. 8 (a), first, the lamp voltage V ₃ which is suppressed to a low lighting start voltage value V _S than the rated operating voltage value V _R is applied to the HID lamp 1.
Therefore, as long as the internal vapor pressure of the lamp 1 immediately after the start of discharge is low, the self-sustained discharge is maintained at a low lighting start voltage value V _S , so that the electrode is less damaged.
[0039]
At this time, since the lamp voltage V ₃ is set low, becomes the DC smoothed voltage V ₂ inputted from the power factor improving circuit 6 by the input voltage control unit to the lamp power control circuit 8 is kept low, thus, the lamp The drop rate of the input / output voltage of the power control circuit 8 is small, and the loss of the chopper circuit 7A can be kept low.
[0040]
Then, when the internal vapor pressure of the lamp 1 is determined to have reached the predetermined value, the lamp power W ₃ is increased to the rated power usage W _R, it takes also much longer time to reach the required amount of light Nor.
[0041]
At this time, not only when the internal vapor pressure of the lamp 1 to start raising the lamp power W ₃ from the time when it is determined to have reached the predetermined value, as shown in FIG. 8 (a), FIG. 8 (b) as shown, after the discharge begins, the lamp power W ₃ is gradually increased to the rated power usage V _R from the start of lighting power V _S and rated operational power W when the internal vapor pressure of the lamp 1 has reached a predetermined value _You may control to become _R.
[0042]
Furthermore, when the resistance value changes while the HID lamp 1 is turned on, for example, the inclusion in the lamp 1 adheres to the electrode, the lamp power control means presets the lamp power. since the voltage controlled so as to coincide with the target power, for example, when turning on at the rated power consumption is, HID lamp 1 is turned on at the proper lamp voltage V ₃ as its power is obtained.
[0043]
In this case, the pulse width of the power control pulse signal is increased / decreased by the length of one clock pulse so that the time average of the lamp power matches the preset target lamp power. Even when it is necessary to control the pulse width of the power control pulse signal for output in units of time less than one clock pulse, the difference of one clock pulse is averaged, and in units of time shorter than the time of one clock pulse. It becomes possible to control electric power.
[0044]
【The invention's effect】
As described above, according to the present invention, the HID lamp can be lit without damaging the electrode immediately after the start of discharge, and when the lamp power is variably controlled by PWM control, it is finer than the clock frequency of the computer. It is possible to control with a high degree of accuracy, and further, it is possible to reduce the heat generated by the switching loss of the chopper circuit without providing a cooling fan or the like.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of a lighting circuit according to the present invention.
FIG. 2 is a circuit diagram showing a power factor correction circuit.
FIG. 3 is a circuit diagram showing a lamp power control circuit.
FIG. 4 is a flowchart showing a processing procedure of a lighting start control unit.
FIG. 5 is a flowchart showing a processing procedure of lamp power control means.
FIG. 6 is a flowchart showing a processing procedure of the input voltage control means.
FIG. 7 is a signal waveform diagram in the power factor correction circuit.
FIG. 8 is a graph showing a change in lamp voltage at the start of lighting.
FIG. 9 is a circuit diagram showing a general lighting circuit.
[Explanation of symbols]
S ... Lighting circuit E ... Power circuit C ... Control unit 1 ... HID lamp 2 ... Main circuit 3 ... Start circuit 6 ... Power factor improvement circuit 7A ... Chopper circuit 8 ......... Lamp power control circuits 10A, 10B, 16 ......... FET (switching element)

Claims (4)

After applying a high voltage starting voltage supplied from the starting circuit (3) to the HID lamp (1) to start discharge, a low voltage lamp voltage corresponding to the lamp power supplied from the main circuit (2) is applied. In the lighting circuit of the HID lamp for self-sustaining discharge,
A lamp power control circuit (8) having a switching element (16) for converting the input DC smoothed voltage into a DC pulse voltage and outputting the target lamp power is formed in the main circuit (2),
After the discharge of the HID lamp (1) is started and before the lamp power of the rated usage power is supplied, the lamp power is reduced to a lighting start power that is lower than the rated usage power and can be self-sustained, and the HID lamp (1) Lighting start control means for outputting a power control pulse signal to the switching element (16) so as to gradually increase the lamp power to the rated operating power when the internal vapor pressure of the lamp reaches a predetermined value;
During the self-sustained discharge, the time average of the lamp power that varies according to the pulse width of the power control pulse signal output to the switching element (16) matches the preset target lamp power. Lamp power control means for increasing or decreasing the pulse width of the power control pulse signal by the length of one clock pulse;
An input voltage control pulse signal is output to the power factor correction circuit (6) connected to the input side of the lamp power control circuit (8), and the power factor improvement circuit (6) to the lamp power control circuit (8). Input voltage control means for variably controlling the input DC smoothed voltage according to the output voltage of the lamp power control circuit (8);
A lighting circuit for an HID lamp, comprising: a control unit (C) having: After applying a high voltage starting voltage supplied from the starting circuit (3) to the HID lamp (1) to start discharge, a low voltage lamp voltage corresponding to the lamp power supplied from the main circuit (2) is applied. In the lighting circuit of the HID lamp for self-sustaining discharge,
A lamp power control circuit (8) having a switching element (16) for converting the input DC smoothed voltage into a DC pulse voltage and outputting the target lamp power is formed in the main circuit (2),
After the discharge of the HID lamp (1) is started and before the lamp power of the rated usage power is supplied, the lamp power is reduced to a lighting start power that is lower than the rated usage power and can be self-sustained, and the HID lamp (1) Control having a lighting start control means for outputting a power control pulse signal to the switching element (16) so as to gradually increase the lamp power to the rated operating power when the internal vapor pressure of the lamp reaches a predetermined value. A lighting circuit for an HID lamp, comprising a section (C). After applying a high voltage starting voltage supplied from the starting circuit (3) to the HID lamp (1) to start discharge, a low voltage lamp voltage corresponding to the lamp power supplied from the main circuit (2) is applied. In the lighting circuit of the HID lamp for self-sustaining discharge,
A lamp power control circuit (8) having a switching element (16) for converting the input DC smoothed voltage into a DC pulse voltage and outputting the target lamp power is formed in the main circuit (2),
After the discharge of the HID lamp (1) is started and before the lamp power of the rated usage power is supplied, the lamp power is reduced to a lighting start power that is lower than the rated usage power and can be self-sustained, and the HID lamp (1) Lighting start control means for outputting a power control pulse signal to the switching element (16) so as to gradually increase the lamp power to the rated operating power when the internal vapor pressure of the lamp reaches a predetermined value;
During the self-sustained discharge, the time average of the lamp power that varies according to the pulse width of the power control pulse signal output to the switching element (16) matches the preset target lamp power. A lighting circuit for an HID lamp, comprising a control unit (C) having lamp power control means for increasing or decreasing the pulse width of the power control pulse signal by the length of one clock pulse. After applying a high voltage starting voltage supplied from the starting circuit (3) to the HID lamp (1) to start discharge, a low voltage lamp voltage corresponding to the lamp power supplied from the main circuit (2) is applied. In the lighting circuit of the HID lamp for self-sustaining discharge,
A lamp power control circuit (8) having a switching element (16) for converting the input DC smoothed voltage into a DC pulse voltage and outputting the target lamp power is formed in the main circuit (2),
After the discharge of the HID lamp (1) is started and before the lamp power of the rated usage power is supplied, the lamp power is reduced to a lighting start power that is lower than the rated usage power and can be self-sustained, and the HID lamp (1) Lighting start control means for outputting a power control pulse signal to the switching element (16) so as to gradually increase the lamp power to the rated operating power when the internal vapor pressure of the lamp reaches a predetermined value;
An input voltage control pulse signal is output to the power factor correction circuit (6) connected to the input side of the lamp power control circuit (8), and the power factor improvement circuit (6) to the lamp power control circuit (8). An HID lamp lighting circuit comprising: a control unit (C) having input voltage control means for variably controlling the input DC smoothed voltage according to the output voltage of the lamp power control circuit (8). .

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