JP2004303507A - Uninterruptive power supply and discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the electric discharge of a lamp by reducing a current flowing to the lamp on the occurrence of momentary power interruption of input power. <P>SOLUTION: This discharge lamp lighting device 10 has a monitor 80 for monitoring the voltage of power inputted from a power source 21; a current detector 70 for detecting the output current of a converter circuit 30; and a controller 90 for performing PWM control of the output current of the converter circuit 30. When the input voltage is lowered to a prescribed value or less, the controller 90 reduces the amount of current outputted from the converter circuit, on the contrary to usual PWM control. The rapid consumption of energy stored inside the device 10 is thereby avoided to maintain electric discharge in a tube of the lamp L. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an uninterruptible power supply device and a discharge lamp lighting device, and continues to supply power to a connected load even when an instantaneous power failure or an instantaneous voltage drop occurs. The present invention relates to an uninterruptible power supply for maintaining discharge and a discharge lamp lighting device.
[0002]
[Prior art]
High-intensity discharge lamps, such as metal halide lamps, high-pressure sodium lamps, and mercury lamps, do not light up when voltage is applied just like filament lamps, and they take time to reach a stable state. Requires a lighting device to control. This lighting device serves as a starter that creates a discharge path between the electrodes of the lamp and increases the current in the discharge path while maintaining the current in the discharge path to transition to arc discharge. And a role as a ballast for controlling the
[0003]
In general, for example, as shown in FIG. 3, a lighting device includes a DC power supply 1, a converter 2 for adjusting DC power from DC power supply 1, an inverter 3 for converting the adjusted DC power to AC power, and a lamp. And an igniter 5 for shifting the discharge generated in 4 from glow discharge to arc discharge. The controller 6 is connected to the converter 2 and the inverter 3 to control the converter 2 and the inverter 3 respectively.
[0004]
The controller 6 supplies a control signal to the switching element Q <b> 1 of the converter 2 to perform PWM (pulse width modulation) control on the input power, and converts the output to AC through the inverter 3 and supplies the AC to the lamp 4. Thus, the power control of the lamp 4 is performed.
[0005]
For example, when the input to the lighting device having the above configuration stops momentarily (the voltage drops momentarily and the power supply stops), the input voltage to the inverter 3 decreases. If the input power to the lamp 4 continues for a certain period of time, the lamp 4 may be turned off because the current supplied to the lamp 4 is not stable. When the lamp 4 is a high-intensity discharge lamp, the re-lighting of the lamp 4 requires a decrease in the temperature of the lamp 4 and a decrease in the pressure in the tube. However, immediately after the lamp 4 is turned off, the temperature and the pressure in the tube are high, and the lamp 4 needs a long time before the temperature drops and the pressure drops. . The relighting time varies depending on the type of the lamp 4 and the like, but for example, about 5 to 15 minutes is required.
[0006]
In addition, when a voltage drop due to a lightning strike or disconnection of a faulty system in the event of a short circuit in the neighborhood, or a voltage drop due to an instantaneous overcurrent due to the start of a large device reaches about 10 to 20 ms (a voltage drop occurs), 4 may be turned off, and it takes a long time until re-lighting as described above.
[0007]
Therefore, in order to maintain the lighting state of the lamp even when the input power decreases, a configuration is adopted in which the capacity of the smoothing capacitor provided in converter 2 is increased to increase the amount of power stored in the lighting device. . When a boost chopper is used as an input to an electronic ballast as disclosed in, for example, JP-A-8-288087, the input voltage for detecting that the input voltage to the electronic ballast of the lamp has dropped is reduced. Detecting means is provided so that when the input voltage decreases, the output current of the boost chopper is increased and the lighting of the lamp is maintained.
[0008]
[Patent Document 1] Japanese Patent Application Laid-Open No. 8-288087 (FIG. 1)
[0009]
[Problems to be solved by the invention]
In recent years, there has been a demand in the market for electronic devices using high-intensity discharge lamps such as projectors, OHPs, and automobile headlights that are small, light, and low in cost. There is a request. Therefore, increasing the capacity of the smoothing capacitor of the converter 2 as a countermeasure against momentary power failure causes an increase in the size of the device, which is contrary to the demand from the market.
[0010]
In addition, the method of increasing the output current of the step-up chopper with a decrease in the input voltage increases the amount of output current in the event of a power failure due to a remarkable decrease in the input voltage, so the energy stored in the device is rapidly reduced. Then, the lamp is turned off, which is not preferable.
[0011]
An object of the present invention is to provide an uninterruptible power supply capable of maintaining a predetermined state of a load even when a power failure or a decrease in input voltage occurs in view of the above problems.
[0012]
It is another object of the present invention to provide a discharge lamp lighting device that maintains a discharge in a discharge lamp tube and avoids turning off even when a power failure or a decrease in input voltage occurs.
[0013]
[Means for Solving the Problems]
An uninterruptible power supply according to claim 1 of the present invention is an uninterruptible power supply that outputs a current to a load using power input from a power supply and maintains the load in a predetermined state, and saves the power. Power storage means, control means for controlling the current output from the power storage means, and voltage monitoring means for monitoring the voltage of the power, wherein the control means reduces the voltage to a predetermined voltage value or less. Then, the predetermined state is maintained by reducing the current.
[0014]
With the above configuration, when the power input from the power supply drops below a predetermined voltage value, the current output from the uninterruptible power supply is reduced, and the load supplied with power from the uninterruptible power supply is brought into a predetermined state. maintain.
[0015]
The uninterruptible power supply according to claim 2, wherein the load is a discharge lamp, and the predetermined state is a discharge in a tube of the discharge lamp. Therefore, when the load is a discharge lamp, when a decrease in input power is detected, the discharge in the discharge lamp tube is maintained while reducing the current supplied from the uninterruptible power supply.
[0016]
A discharge lamp lighting device according to claim 3 of the present invention is a discharge lamp lighting device for controlling lighting of a discharge lamp, and a power supply unit that supplies current to the discharge lamp using power input from a power supply. Input voltage monitoring means for monitoring the input voltage of the power, current detection means for detecting the current amount of the current, output voltage detection means for detecting the output voltage of the current, Control means for controlling the current based on the output voltage, and the control means reduces the current to maintain the discharge in the discharge lamp when the input voltage falls below a predetermined value. It is characterized by doing.
[0017]
According to the above configuration, when the power input from the power supply drops below a predetermined voltage value, the current output from the power supply unit is reduced while maintaining the discharge in the discharge lamp tube.
[0018]
The discharge lamp lighting device according to claim 4 of the present invention is a discharge lamp lighting device for controlling lighting of the discharge lamp, and a power supply unit that supplies a current to the discharge lamp using power input from a power supply. Input voltage monitoring means for monitoring the input voltage of the power, current detection means for detecting the current amount of the current, output voltage detection means for detecting the output voltage of the current, Control means for performing PWM control of the current based on the output voltage obtained, wherein the control means reduces the on-duty of the PWM control when the input voltage falls below a predetermined value to reduce the inside of the discharge lamp. Is maintained.
[0019]
According to the above configuration, when the power input from the power supply decreases to a predetermined voltage value or less, the on-duty for performing the PWM control of the current output from the power supply unit while maintaining the discharge in the discharge lamp tube is maintained. By decreasing the current, the current output from the power supply means is reduced.
[0020]
A discharge lamp lighting device according to claim 5 of the present invention is a discharge lamp lighting device that controls lighting of a discharge lamp, and a power supply unit that supplies current to the discharge lamp using power input from a power supply. Input voltage monitoring means for monitoring an input voltage of the power, current detection means for detecting a current amount of the current, output voltage detection means for detecting an output voltage of the current, output voltage detected and detected Control means for performing PWM control of the current to a target value based on the amount of the current, wherein the control means detects the input voltage and the detected input voltage when the input voltage falls below a predetermined voltage value. The discharge value in the discharge lamp is maintained by reducing the target value based on the amount of current and reducing the on-duty ratio of the PWM control.
[0021]
According to the above configuration, when the power input from the power supply decreases to a predetermined voltage value or less, the target value and the target value when the current output from the power supply unit is subjected to PWM control while maintaining the discharge in the discharge lamp tube. The on-duty is reduced to reduce the current output from the power supply means.
[0022]
A discharge lamp lighting device according to claim 6 of the present invention is a discharge lamp lighting device that controls lighting of a discharge lamp, and a power supply unit that supplies a current to the discharge lamp using power input from a power supply. Input voltage detecting means for detecting an input voltage of the power, current detecting means for detecting a current amount of the current, output voltage detecting means for detecting an output voltage of the current, an output of the current detecting means, Control means for performing PWM control of the current according to the power obtained by multiplying the output of the output voltage detection means, the control means, when the input voltage is reduced to a predetermined voltage value or less, After the detected current amount is multiplied by k times (where k> 1), the current is output from the current detecting means to maintain the discharge in the discharge lamp.
[0023]
According to the above configuration, when the power input from the power supply falls below a predetermined voltage value, the current detected by the current detecting means is multiplied by k while maintaining the discharge in the tube of the discharge lamp. Then, it is determined that the power output from the power supply means has increased, and the current output from the power supply means is reduced.
[0024]
The discharge lamp lighting device according to claim 7 of the present invention is a discharge lamp lighting device for controlling lighting of a discharge lamp, and a power supply unit that supplies current to the discharge lamp using power input from a power supply. Input voltage monitoring means for monitoring the input voltage of the power, output voltage detection means for detecting the output voltage of the current, current detection means for detecting the amount of current of the current, Control means for performing PWM control of the current to a target value based on the amount of current obtained, and the control means reduces the target value when the input voltage decreases to a predetermined voltage value or less. It is characterized by maintaining the discharge in the discharge lamp.
[0025]
According to the above configuration, when the power input from the power supply falls to a predetermined voltage value or less, the power supply unit reduces the target value when performing the PWM control of the current while maintaining the discharge in the tube of the discharge lamp. Reduce the current output from.
[0026]
The discharge lamp lighting device according to claim 8 of the present invention is characterized in that, in the discharge lamp lighting device according to any one of claims 3 to 7, the power supply means includes a power storage means for storing the power.
[0027]
With the above configuration, when the power input from the power supply drops below a predetermined voltage value, the power stored in the power storage unit is supplied from the power supply unit to the discharge lamp, and the discharge in the discharge lamp tube is maintained. .
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the discharge lamp lighting device according to the present invention. 1, the discharge lamp lighting device 10 includes an input circuit 20, a converter circuit 30, an inverter circuit 40, an igniter circuit 50, an output voltage detection circuit 60, a current detection circuit 70, and an input voltage drop detection circuit 80. And a controller 90 for controlling lighting of the lamp L. In the present invention, the lamp L refers to a high-intensity discharge lamp such as a metal halide lamp, a high-pressure sodium lamp, and a mercury lamp that emits light by discharging in metal vapor.
[0029]
Input circuit 20 is connected to, for example, a commercial power supply 21, and outputs the rectified AC voltage V ₀ which is input from the commercial power source 21 into a DC voltage V _in between the lines A and B. Input circuit 20 further includes a smoothing capacitor (not shown) therein, and outputs the smoothing the fluctuations of the rectified DC voltage V _in. The input circuit 20, instead of using a commercial power supply 21, the output may be used DC power source V _in.
[0030]
Converter circuit 30 includes a chopper circuit having a switching element (not shown) and performing PWM control of an output, and outputs DC power between line C and line D. The point G on the line D is set as a reference potential. The inverter circuit 40 is connected between the line C and the line D, converts DC power output from the converter circuit 30 into AC power, and outputs the AC power between the line E and the line F. The igniter circuit 50 generates a pulse voltage for starting the lamp L. The igniter circuit 50 is inserted into the line C so that its output is superimposed on the output of the inverter circuit 40. The lamp L is connected between output terminals of the inverter circuit 40.
[0031]
The voltage detection circuit 60 detects the output voltage _Vout of the converter circuit 30, and is configured by connecting two resistors R1 and R2 in series between a line A and a line B. The voltage detection circuit 50 detects the output voltage _Vout of the converter circuit 30 by dividing the output voltage _Vout into two resistors R1 and R2, and outputs it as an output voltage signal.
[0032]
The current detection circuit 70 includes a resistor R3 inserted between the reference potential point G and the input terminal on the low potential side of the inverter circuit 40 on the line D, and detects the output current of the converter circuit 30. An amplification circuit 72 is connected to the current detection circuit 70 via a resistor R4, and amplifies an output current signal detected by the current detection circuit 70 and corresponding to an output current.
[0033]
The amplifier circuit 72 is a well-known non-inverting amplifier circuit including an operational amplifier 72a and a plurality of resistors R5, R6, and R7. The resistor R5 is connected between the inverting input terminal and the output terminal of the operational amplifier 72a, and the resistor R6 is connected between the inverting input terminal of the operational amplifier 72a and the reference potential point G. Further, the resistor R7 and the switching element SW connected in series are connected in parallel to the resistor R6, and by the conduction operation of the switching element SW, the resistor R6 is electrically connected in parallel with the resistor R6 and the amplification degree of the amplifier circuit 72 is increased. Is to be increased.
[0034]
Input voltage drop detection circuit 80 is connected to the input circuit 20 monitors the output voltage V _in of the input circuit 20. Then, the input voltage detection circuit 80, the output voltage V _in falls below a predetermined value, and outputs an input voltage drop detection pulse to the switching element SW of the amplifier 72, the switching element SW in the conductive state.
[0035]
The controller 90 controls the output of the converter circuit 30 and includes an arithmetic circuit 91 and a PWM controller 92. The arithmetic circuit 91 is mainly composed of a microcomputer, receives outputs from the power detection circuit 60 and the current detection circuit 70, and calculates the output power P _out of the converter circuit 30 based on both outputs. The output of the arithmetic circuit 91 is a digital value, and the PWM controller 92 is composed of an analog circuit. Therefore, a D / A converter 93 is provided between the arithmetic circuit 91 and the PWM controller 92. The D / A converter 93 is configured by a known R-2R ladder, and converts a digital value into an analog value. The output of the D / A converter 93 is sent to the operational amplifier 94 and compared with the current signal of the output current that has already been detected and amplified. The PWM controller 92 issues a control signal to the converter circuit 30 in accordance with the output of the operational amplifier 94, and performs PWM control on the output of the converter circuit 30. Thus, the discharge lamp lighting device 10 is configured.
[0036]
Next, the operation of the discharge lamp lighting device 10 will be described. After a current starts to flow from the input circuit 20 to the lamp L and is started by the igniter circuit 50 and the lighting state of the lamp L reaches a stable state, that is, reaches a steady state, the voltage detection circuit 60 and the current detection circuit 70 cause the converter circuit to operate. detecting the output voltage _{V out} and output current _{I out} of 30. In the controller 90, the output power of the converter circuit 30 is calculated by the calculation circuit 91 based on the output voltage signal _Vout and the output current signal _Iout, and the digital output is converted to an analog voltage by the D / A converter 93. The PWM pulse is applied from the PWM controller 92 to the switching element of the converter circuit 30 by comparing with the voltage corresponding to the already detected and amplified output current _Iout , and the PWM control of the converter circuit 30 is performed.
[0037]
Then, when the instantaneous blackout occurs to a power supply 21, the output voltage _{V in} of the input circuit 20 is significantly reduced. Thus, when the output voltage V _in falls below a predetermined value, the input voltage detection circuit 80 toward the input voltage drop pulses to the amplifier 72 output. In response to the input voltage drop pulse, the amplifier 72 increases the degree of amplification of the output current signal output from the output current detection circuit 70. Therefore, the output current signal after amplification is not actually even a decrease has occurred, when it is input to the arithmetic circuit 91, or is maintained substantially at the same signal level as the pre-reduction of the input voltage V _in, conversely Since the output power increases, the output power P _out of the converter circuit 30 has apparently increased. Therefore, since the output power of the inverter circuit calculated by the calculation circuit 91 increases, the operational amplifier 94 and the PWM controller 92 control the converter circuit 30 so as to reduce the output current of the converter circuit 30.
[0038]
As described above, the normal PWM control is performed on the lamp L in the steady state. However, when an instantaneous interruption of the input power occurs, the controller 90 determines that the output power has increased by forcibly increasing the output current I _out detected by the current detection circuit 70 when calculating the output power. Let me. For this reason, since the controller 90 performs the PWM control to lower the output power, the output current of the converter circuit 30 can be immediately reduced to the rated value or less. Accordingly, by keeping the discharge of the lamp L while suppressing the discharge of the electric energy stored in the capacitor of the input circuit 20 at the time of the instantaneous power failure, it is possible to prevent the lamp L from being turned off during the instantaneous power failure.
[0039]
Further, when an instantaneous interruption of the input voltage occurs, the output current from the converter circuit 30 is reduced without performing any special processing in the arithmetic circuit 91, so that the processing time of the arithmetic circuit 91 is not delayed. The output current from the converter circuit 30 can be reduced with a quick response.
[0040]
Further, since the discharge of the lamp L is maintained even if the momentary power failure occurs, the control of the converter circuit 30 by the controller 90 immediately returns to the normal PWM control upon recovery from the momentary power failure. Is increased to a desired current value, and the lighting of the lamp L can be returned to a desired luminance.
[0041]
Next, a discharge lamp lighting device according to a second embodiment of the present invention will be described with reference to FIG. 2, the input voltage detection circuit 80 monitors the input voltage V _in of the input circuit 20, when the input voltage V _in falls below a predetermined value, the output to the D / A converter 93 of the controller 90 Emit. The D / A converter 93 is configured to reduce a reference voltage used when converting a digital value to an analog value in response to an input from the input voltage drop detection circuit 80. The amplifier 72 that amplifies the detected output current is a well-known non-inverting amplifier circuit including an operational amplifier 72a and two resistors R5 and R6, and has a constant amplification. The other configuration is the same as that of the discharge lamp lighting device 10 shown in FIG. 1, and the same reference numerals are given and the detailed description is omitted.
[0042]
Next, the operation of the discharge lamp lighting device 10 shown in FIG. If the instantaneous blackout occurs to a power supply 21, the output voltage V _in of the input circuit 20 is significantly reduced. Thus, when the output voltage V _in falls below a predetermined value, the input voltage detection circuit 80 generates an output toward the D / A converter 93. On the other hand, the arithmetic circuit 91 uses the voltage signal corresponding to the output voltage V _out detected by the voltage detection circuit 60 and the current signal corresponding to the output current I _out detected and amplified by the current detection circuit 70 in the arithmetic circuit 91. The output power is calculated, and the result is input to the D / A converter 93. In the D / A converter 93, since the reference voltage is reduced in response to the output of the input voltage drop detection circuit 80, the target output power value at the time of performing the PWM control is lower than the value at the normal time. . Therefore, the PWM controller 92 issues a control signal to the converter circuit 30 to reduce the output current from the converter circuit 30 with respect to the output power P _out of the converter circuit 30 output from the arithmetic circuit 91.
[0043]
As described above, when the momentary power failure occurs, the controller 90 can quickly reduce the current value output from the converter circuit 30 to a value equal to or less than the rating by reducing the target output current value of the PWM control. Accordingly, by keeping the discharge of the lamp L while suppressing the discharge of the electric energy stored in the capacitor of the input circuit 20 at the time of the instantaneous power failure, it is possible to prevent the lamp L from being turned off during the instantaneous power failure.
[0044]
Further, when an instantaneous interruption of the input voltage occurs, the output current from the converter circuit 30 is reduced without performing any special processing in the arithmetic circuit 91, so that the processing time of the arithmetic circuit 91 is not delayed. The output current from the converter circuit 30 can be reduced with a quick response.
[0045]
In the above-described embodiment, the current output from the converter circuit is reduced in response to the momentary power failure. However, as a method for reducing the current output from the converter circuit, (1) reducing the level of the output current A method, (2) a method of reducing the duty when performing the PWM control, (3) a method of reducing the target value of the PWM control, and the like can be used.
[0046]
In addition, while reducing the electric power output from the converter circuit in response to the momentary power failure, suppressing the discharge of the electric energy stored in the capacitor of the input circuit 20 at the time of the momentary power failure, while maintaining the discharge of the lamp L, It is also possible to prevent the lamp L from being turned off during the instantaneous stop period. It should be noted that the above-described embodiment only exemplifies a part of the preferred embodiment of the present invention, and the present invention is not limited to the above-described configuration.
[0047]
【The invention's effect】
According to the uninterruptible power supply of claim 1 of the present invention, even when the power input from the power supply drops below a predetermined voltage value, the load supplied with power from the uninterruptible power supply can be maintained in a predetermined state. .
[0048]
According to the uninterruptible power supply according to claim 2 of the present invention, when the power input from the power supply is reduced, the current supplied from the uninterruptible power supply to the discharge lamp is reduced, but the power supply in the discharge lamp tube is reduced. Discharge can be maintained.
[0049]
According to the discharge lamp lighting device of the third aspect of the present invention, the discharge in the discharge lamp tube can be maintained even if the electric power input from the power supply falls below the predetermined voltage value.
[0050]
According to the discharge lamp lighting device of the fourth aspect of the present invention, even if the power input from the power supply drops below the predetermined voltage value, the on-duty of the PWM control is reduced, so Discharge can be maintained.
[0051]
According to the discharge lamp lighting device of the fifth aspect of the present invention, the target value and the on-duty of the PWM control are reduced even if the power input from the power supply falls below the predetermined voltage value. Discharge in the tube can be maintained.
[0052]
According to the discharge lamp lighting device of the sixth aspect of the present invention, when the power input from the power supply decreases to a predetermined voltage value or less, the detected current is apparently increased, so that the control means controls the power supply means. Since it is determined that the power output from the power supply has increased, the current output from the power supply means can be reduced to maintain the discharge in the discharge lamp tube.
[0053]
According to the discharge lamp lighting device according to claim 7 of the present invention, when the power input from the power supply decreases to a predetermined voltage value or less, the target value at the time of performing the PWM control of the current is reduced, so that the discharge lamp The current output from the power supply means can be reduced while maintaining the discharge in the tube.
[0054]
According to the discharge lamp lighting device of the present invention, when the power input from the power supply falls below the predetermined voltage value, the power stored in the power storage means is supplied from the power supply means to the discharge lamp. As a result, the discharge in the discharge lamp tube can be maintained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a first embodiment of an uninterruptible power supply according to the present invention.
FIG. 2 is a configuration diagram showing a second embodiment of the uninterruptible power supply of the present invention.
FIG. 3 is a configuration diagram illustrating an example of a conventional discharge lamp lighting device.
[Explanation of symbols]
L Discharge lamp 10 Uninterruptible power supply 30 Power supply means 60 Output voltage detection means 70 Current detection means 80 Input voltage monitoring means 90 Control means

Claims (8)

An uninterruptible power supply that outputs a current to a load using power input from a power supply and maintains the load in a predetermined state,
Power storage means for storing the power,
Control means for controlling the current output from the power storage means,
Voltage monitoring means for monitoring the voltage of the power,
An uninterruptible power supply device, characterized in that when the voltage drops below a predetermined voltage value, the control means reduces the current and maintains the predetermined state. The uninterruptible power supply according to claim 1, wherein the load is a discharge lamp, and the predetermined state is discharge in a tube of the discharge lamp. A discharge lamp lighting device for controlling lighting of a discharge lamp,
Power supply means for supplying current to the discharge lamp using power input from a power supply,
Input voltage monitoring means for monitoring the input voltage of the power,
Current detection means for detecting a current amount of the current;
Output voltage detecting means for detecting an output voltage of the current;
Control means for controlling the current based on the detected current amount and the detected output voltage, wherein the control means reduces the current when the input voltage falls below a predetermined value. A discharge lamp lighting device characterized by maintaining discharge in the discharge lamp. A discharge lamp lighting device for controlling lighting of a discharge lamp,
Power supply means for supplying current to the discharge lamp using power input from a power supply,
Input voltage monitoring means for monitoring the input voltage of the power,
Current detection means for detecting a current amount of the current;
Output voltage detecting means for detecting an output voltage of the current;
Control means for performing PWM control of the current based on the detected current amount and the detected output voltage, wherein the control means controls the on-duty of the PWM control when the input voltage falls below a predetermined value. A discharge lamp lighting device characterized by maintaining a discharge in the discharge lamp by reducing the ratio. A discharge lamp lighting device for controlling lighting of a discharge lamp,
Power supply means for supplying current to the discharge lamp using power input from a power supply,
Input voltage monitoring means for monitoring the input voltage of the power,
Current detection means for detecting a current amount of the current;
Output voltage detecting means for detecting an output voltage of the current;
Control means for performing PWM control on the current to a predetermined current value based on the detected output voltage and the detected current amount, the control means comprising: when the input voltage falls below a predetermined voltage value, A discharge lamp lighting device for reducing the predetermined current value based on a detected input voltage and a detected amount of current, and maintaining a discharge in the discharge lamp by reducing an on-duty ratio of PWM control. . A discharge lamp lighting device for controlling lighting of a discharge lamp,
Power supply means for supplying current to the discharge lamp using power input from a power supply,
Input voltage detection means for detecting the input voltage of the power,
Current detection means for detecting a current amount of the current;
Output voltage detecting means for detecting an output voltage of the current;
Control means for performing PWM control on the current according to the power obtained by multiplying the output of the current detection means and the output of the output voltage detection means;
The control means, when the input voltage falls below a predetermined voltage value, multiplies the detected current amount by k times (however, k> 1), outputs the detected current amount from the current detection means, and outputs the current amount. A discharge lamp lighting device characterized by maintaining discharge in an electric lamp. A discharge lamp lighting device for controlling lighting of a discharge lamp,
Power supply means for supplying current to the discharge lamp using power input from a power supply,
Input voltage monitoring means for monitoring the input voltage of the power,
Output voltage detecting means for detecting an output voltage of the current;
Current detection means for detecting a current amount of the current;
Control means for performing PWM control on the current to a predetermined value based on the detected output voltage and the detected current amount;
A discharge lamp lighting device, characterized in that when the input voltage falls below a predetermined voltage value, the control means reduces the predetermined value to maintain the discharge in the discharge lamp. The discharge lamp lighting device according to claim 3, wherein the power supply unit includes a power storage unit that stores the power.

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