JP2006286322A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device facilitating adjustment for an actual use condition of discharge lamp light modulation. <P>SOLUTION: A light modulation control circuit 4 for driving and controlling an inverter circuit outputting a high-frequency voltage to a discharge lamp by a light modulation control voltage of the discharge lamp generated on the basis of a light modulation signal includes: a light modulation control voltage generation circuit 5 for generating a D.C. voltage having a voltage value linearly dropping as the pulse width of the light modulation signal increases to output it as the light modulation control voltage of the discharge lamp; a light modulation lower-limit temperature compensation circuit 6 used for generating a lower-limit control voltage for setting the lower limit of a light modulation range of the discharge lamp below a predetermined temperature and for outputting the lower-limit control voltage when the control voltage is set lower than the lower-limit control voltage and having a negative temperature characteristic; and a light modulation lower limiter circuit 7 for generating a lower limiter control voltage for setting the lower limit of the light modulation range of the discharge lamp above the predetermined temperature and for outputting the lower limiter control voltage when the control voltage is set lower than the lower-limit control voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device capable of continuously dimming, and more particularly, to a discharge lamp lighting device that can be easily adjusted to the actual use state of dimming of a discharge lamp.

  A conventional discharge lamp lighting device includes a DC power source that converts commercial power into a DC voltage, an inverter circuit that converts a DC voltage generated from the DC power source into a high-frequency voltage, and an AC voltage generated from the inverter circuit as a discharge lamp. A discharge lamp lighting device having a load circuit to supply, generating a DC voltage whose voltage value decreases linearly as the pulse width of the dimming signal increases, and using this as a control voltage for dimming the discharge lamp A dimming control voltage generation circuit that outputs to the inverter circuit side and a lower limit control voltage that sets the lower limit of the dimming range of the discharge lamp based on the partial pressure by a plurality of impedance elements that have negative temperature characteristics in part. A dimming lower limit setting circuit that outputs the lower limit control voltage to the inverter circuit side when the control voltage is lower than the lower limit control voltage.

Then, the dimming control voltage generation circuit outputs a DC voltage whose voltage value decreases linearly as the pulse width of the dimming signal increases to the inverter circuit side as the dimming control voltage of the discharge lamp, and sets the dimming lower limit. Since the circuit outputs the lower limit control voltage to the inverter circuit side when the control voltage falls below the set lower limit control voltage, even if the lower limit of the dimming range is different, the dimming curve up to the lower limit value Because the lower limit value of the dimming range is set by the dimming lower limit setting circuit, even discharge lamp lighting devices with different lower dimming range limits can be easily combined on the same lighting system. (For example, see Patent Document 1).
Japanese Patent Laid-Open No. 2001-244095 (first page, FIG. 1)

In the conventional discharge lamp lighting device, in order to prevent flickering of the discharge lamp at low temperature and low dimming, the dimming lower limit setting circuit has a negative temperature characteristic so as to increase the lower limit control voltage. The power at the lower limit of light depends on temperature.
In addition, there is a demand that the power at the lower limit of dimming must be within a narrow range since the difference in brightness of the discharge lamp can be visually perceived even at a small power difference at the lower limit of dimming compared to when all lights are lit.
By the way, for each product of the discharge lamp lighting device, the brightness of the dimming varies depending on the product from the variation of individual component accuracy, so it is necessary to adjust to a predetermined brightness. At this time, dimming is adjusted based on the lower limit of dimming.

The temperature in the actual use state of the temperature compensation element of the product of the discharge lamp lighting device is about 45 ° C., whereas the temperature in the production process of the product is in the range of 25 ° C. to 35 ° C. equivalent to room temperature.
And since adjustment of the light control at the time of the light control lower limit in a product is performed in a production process, when adjusting light control in a production process so that it may be in the adjustment range in the temperature of an actual use state, it is 25, for example. Since the negative temperature characteristic is greatly affected in the environment of about 45 ° C in the actual use state in the environment of ℃ and 35 ° C, if you try to fall within the adjustment range at the temperature in the actual use state, the production process The adjustment of dimming at the lower limit of dimming is substantially narrow, and the power at the lower limit of dimming is difficult to adjust because of the requirement that the power must be adjusted to a narrow range. there were.
The present invention has been made to solve such a problem, and an object of the present invention is to provide a discharge lamp lighting device that can be easily adjusted to the actual use state of dimming of the discharge lamp.

  A discharge lamp lighting device according to the present invention includes an inverter circuit that converts a DC voltage into a high-frequency voltage, a load circuit that supplies an AC voltage generated from the inverter circuit to the discharge lamp, and a discharge lamp generated based on a dimming signal And a dimming control circuit for driving and controlling the inverter circuit with a dimming control voltage of the dimming control circuit, wherein the dimming control circuit has a voltage value that is linear as the pulse width of the dimming signal increases. A dimming control voltage generating means for generating a dc voltage that drops to the inverter circuit side as a dimming control voltage of the discharge lamp, and a lower limit for setting a lower limit of the dimming range of the discharge lamp below a predetermined temperature A dimming lower limit temperature compensating means having a negative temperature characteristic that generates a control voltage and outputs the lower limit control voltage to the inverter circuit side when the control voltage falls below the lower limit control voltage; A lower limit limiter control voltage for setting a lower limit of the dimming range of the discharge lamp at a temperature equal to or higher than the temperature, and when the control voltage falls below the lower limit control voltage, the lower limit limiter control voltage is output to the inverter circuit side And a limiter means.

  As described above, the dimming control circuit of the discharge lamp lighting device of the present invention includes a dimming control voltage generating unit that outputs the dimming control voltage of the discharge lamp generated based on the dimming signal to the inverter circuit side, and a predetermined In addition to the dimming lower limit temperature compensation means having a negative temperature characteristic that outputs a lower limit control voltage that sets the lower limit of the dimming range of the discharge lamp to the inverter circuit side at a temperature equal to or lower than a predetermined temperature, the dimming of the discharge lamp is performed at a predetermined temperature or higher. A lower limit limiter control voltage for setting the lower limit of the light range is generated, and when the control voltage is lower than the lower limit control voltage, a dimming lower limiter means for outputting the lower limiter control voltage to the inverter circuit side is newly provided. The dimming lower limiter means operates at a predetermined temperature or higher including the temperature in the production process of the discharge lamp lighting device and the temperature in the actual use state. Even if light adjustment is performed in the production process, it does not depend on the negative temperature characteristics, so the production process is considered by making the adjustment range at the temperature of the production process the same as the adjustment range at the temperature in actual use. The design is easy, and there is an effect that the adjustment range is larger than the conventional one and the adjustment is easy.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a discharge lamp lighting device according to Embodiment 1 of the present invention, FIG. 2 is a circuit diagram showing a configuration of a dimming control circuit of the discharge lamp lighting device, and FIG. The graph which shows the relationship between the input voltage and temperature of a light control lower limit, (b) is a graph which shows the relationship between the adjustment range of light control lower limit, and temperature.
In FIG. 1, a discharge lamp lighting device according to the first embodiment includes a DC power source 1 that converts a commercial power source E into a DC voltage, an inverter circuit 2 that converts a DC voltage of the DC power source 1 into a high-frequency voltage, and an inverter circuit 2. A load circuit 3 that supplies an AC voltage generated from the discharge lamp to the discharge lamp, a dimming control circuit 4 that generates a dimming control voltage of the discharge lamp that is a DC voltage based on the dimming signal LS, and outputs the dimming control voltage to the inverter circuit 2. It is configured with.

  The dimming control circuit 4 generates a DC voltage whose voltage value decreases linearly as the pulse width of the dimming signal LS increases, and outputs this as a dimming control voltage for the discharge lamp. 5, a dimming lower limit temperature compensation circuit 6 having a negative temperature characteristic for generating and outputting a lower limit control voltage for setting a lower limit of the dimming range of the discharge lamp below a predetermined temperature, and a discharge lamp above a predetermined temperature The dimming lower limiter circuit 7 that generates and outputs a lower limit control voltage that sets the lower limit of the dimming range, the dimming control voltage of the dimming control voltage generation circuit 5, and the lower limit control of the dimming lower limit temperature compensation circuit 6 A dimming control voltage output circuit 8 that selects the voltage and the lower limit limit control voltage of the dimming lower limiter circuit 7 and outputs it to the inverter circuit 2 is provided.

Next, the circuit configuration of the dimming control circuit 4 will be described in detail with reference to FIG.
The dimming control voltage generation circuit 5 emits light when the dimming signal is at a high level, and the bridge circuit 11 of four diodes D1 to D4 for making the direction of the pulse waveform of the dimming signal LS (PWM signal) constant. And a photocoupler 12 including a phototransistor PT that is turned on when the light emitting diode LED emits light.
The collector of the phototransistor PT is connected to a 10V DC power supply line Vcc via a current limiting resistor R3. A Zener diode DZ1 that clips a DC voltage is connected to the DC power supply line Vcc, and a smoothing capacitor C4 is connected in parallel to the Zener diode DZ1.

Further, the dimming control voltage generation circuit 5 is connected in parallel with the resistor R4 to the phototransistor PT, and is turned off when the phototransistor PT is turned on, and connected in parallel to the transistor Q1 and turned on when the transistor Q1 is turned on. NPN field effect transistor Q3 which is turned off when PNP type field effect transistor Q2 and transistor Q1 are turned on, and resistors R5 and R6 provided between the source of field effect transistor Q2 and the drain of field effect transistor Q3, The capacitor C2 is connected between the connection point of the resistors R5 and R6 and the line on the ground side through the resistor R7, and repeats charging and discharging by alternately turning on and off the field effect transistor Q2 and the field effect transistor Q3. It is configured.
The resistor R4 and the drain of the field effect transistor Q2 are connected to the DC power supply line Vcc, and the emitter of the phototransistor PT, the transistor Q1, and the source of the field effect transistor Q3 are connected to the ground side line.

In the dimming control voltage generation circuit 5, when the dimming signal is at a high level, the transistor Q1 is turned off, the transistor Q2 is turned on, the transistor Q3 is turned off, and a direct current is passed through the transistor Q2 and the resistors R5 and R7. The capacitor C2 flows and the capacitor C2 is charged.
When the dimming signal is at a low level, the transistor Q1 is turned on, the field effect transistor Q2 is turned off, the field effect transistor Q3 is turned on, the capacitor C2 is discharged, and the DC current is discharged into the resistor R7, the resistor R6 flows to transistor Q3.
The voltage value of the capacitor C2 linearly decreases as the ON period (pulse width of the dimming signal) of the field effect transistor Q2 becomes longer.
Note that the “round” of the pulse waveform of the dimming signal generated in the phototransistor PT is shaped by the alternating switching operation of the field effect transistors Q2 and Q3.

The dimming lower limit temperature compensation circuit 6 includes a resistor R8, a thermistor RT1, and a resistor R9 connected in series between the 10V DC power supply line Vcc and the ground side line.
When the lower limit of the luminous flux output of the discharge lamp is set to 40% below a predetermined temperature, the dimming lower limit temperature compensation circuit 6 sets the lower limit control voltage necessary to obtain the output to the resistor R8, the thermistor RT1 and the resistor R9. When the control voltage generated by the duty of the dimming signal is lower than the lower limit control voltage, the ON period of the switching element of the inverter circuit 2 is determined by the lower limit control voltage. In the dimming lower limit temperature compensation circuit 6, when the dimming is performed at a low temperature, the luminous flux is reduced due to the characteristics of the discharge lamp. Since the lower limit control voltage is increased, the luminous flux output of the discharge lamp can be secured.

The dimming lower limiter circuit 7 is composed of resistors R10 and R11 and a volume resistor VR1 connected in series between a 10V DC power supply line Vcc and a ground side line.
When the lower limit of the luminous flux output of the discharge lamp is set to 40% at a predetermined temperature or higher, the dimming control voltage output circuit 5 sets the lower limiter control voltage necessary for obtaining the output to the resistors R10 and R11 and the volume resistor RVR1. When the control voltage generated by the duty of the dimming signal is lower than the lower limit limiter control voltage, the ON period of the switching element of the inverter circuit 2 is determined by the lower limit limiter control voltage. . That is, in this case, the lower limit of the luminous flux output of the discharge lamp is fixed at 40%.

The dimming control voltage output circuit 8 outputs the dimming control voltage of the dimming control voltage generation circuit 5, the lower limit control voltage of the dimming lower limit temperature compensation circuit 6, and the highest lower limit limiter control voltage of the dimming lower limit limiter circuit 7. The operational amplifier OP1 to be selected and the operational amplifier OP2 that outputs the control voltage selected by the operational amplifier OP1 to the inverter circuit 2 are mainly configured.
The negative input terminal for one reference voltage of the operational amplifier OP1 is connected to the connection point between the resistors R10 and R11 of the dimming lower limiter circuit 7, and the other positive input terminal is connected to the connection point between the capacitor C2 and the resistor R7. The output terminal is connected to the negative input terminal via the diode D5.

Further, one negative input terminal of the operational amplifier OP2 is connected to a connection point between the resistor R8 of the dimming lower limit temperature compensation circuit 6 and the thermistor RT1 through the diode D6, and the other positive side fed back to the output terminal. The input terminal is connected to the ground side line through voltage dividing resistors R12 and R13. The connection point of the voltage dividing resistors R12 and R13 is connected to the inverter circuit 2 via the noise removing circuit 13 of the resistor R14 and the capacitor C3.
The ON period of the switching element of the inverter circuit 2 is determined by the voltage (control voltage) generated at the connection point of the voltage dividing resistors R12 and R13. That is, if the voltage of the capacitor C2 increases, the ON period of the switching element of the inverter circuit 2 Becomes longer and the luminous flux of the discharge lamp increases. Conversely, when the voltage of the capacitor C2 is lowered, the ON period of the switching element is shortened and the luminous flux of the discharge lamp is reduced.

Next, the operation of the dimming control circuit of the discharge lamp lighting device according to the first embodiment will be described.
First, when the field effect transistor Q2 is turned on and the field effect transistor Q3 is turned off, a DC current flows from the DC power supply line Vcc through the path of the transistor Q2, the resistor R5, the resistor R7, and the capacitor C2, and the dimming signal The capacitor C2 is charged according to the duty.
Next, when the field effect transistor Q2 is turned off and the field effect transistor Q3 is turned on, the charging voltage charged in the capacitor C2 is discharged from the capacitor C2 through the path of the resistor R7, the resistor R6, and the field effect transistor Q3. Is done.

When a dimming signal with a duty of 5% is input, the on-period of the field effect transistor Q3 is short, so the time for discharging from the capacitor C2 to the field effect transistor Q3 is short, and the on-period of the field effect transistor Q2 And the time for charging the capacitor C2 via the resistor R7 becomes longer. Therefore, a high control voltage is generated at which the luminous flux output of the discharge lamp becomes 100%.
In this state, when the duty of the dimming signal is gradually increased, the ON period of the field effect transistor Q3 is gradually increased accordingly, and the time for discharging from the capacitor C2 to the field effect transistor Q3 side is gradually increased. The on-period of the field effect transistor Q2 is shortened, and the time for charging the capacitor C2 via the resistor R7 is shortened, and the control voltage is lowered. At this time, the luminous flux output of the discharge lamp gradually decreases.

In this way, when the light control signal duty increases and the luminous flux output of the discharge lamp decreases, as shown in FIG. 3A, the light control lower limit temperature compensation circuit 6 is below a predetermined temperature of, for example, 15 ° C. In, a lower limit control voltage based on a negative temperature characteristic is set.
The dimming lower limiter circuit 7 is set with a predetermined lower limiter control voltage at a predetermined temperature of, for example, 15 ° C. or higher. The lower limiter control voltage can be varied by adjusting the resistance value with the volume resistor VR1.
When the control voltage of the dimming control voltage generation circuit 5 falls below the lower limit control voltage set by the dimming lower limit temperature compensation circuit 6, the dimming control voltage output circuit 8 sets the lower limit control voltage to the inverter circuit side. Output. The dimming control voltage output circuit 8 also converts the lower limit limiter control voltage into an inverter even when the control voltage of the dimming control voltage generation circuit 5 is lower than the lower limit limiter control voltage set by the dimming lower limiter circuit 7. Output to the circuit side.

When the ambient temperature is 15 ° C. or higher, the voltage of the capacitor C2, which is the control voltage generated by the dimming control voltage generation circuit 5 according to the duty of the dimming signal, is applied to the negative input terminal of the operational amplifier OP1. When the voltage is higher than the output voltage, the voltage output from the output terminal of the operational amplifier OP1 via the diode D6 is the same voltage as the voltage input to the plus side input terminal.
Therefore, the control voltage generated according to the duty of the dimming signal is input to the negative input terminal of the operational amplifier OP2, and the voltage amplified by the operational amplifier OP2 at a predetermined amplification factor is divided by the voltage dividing resistors R12 and R13. The control voltage, which is the obtained voltage, is input to the inverter circuit 2.

Further, when the control voltage generated by the dimming control voltage generation circuit 5 according to the duty of the dimming signal is lower than the voltage applied to the negative side input terminal of the operational amplifier OP1, the voltage is output from the output terminal of the operational amplifier OP1. Is not output, the voltage divided by the resistors R10, R11 and the volume resistor VR1 of the dimming lower limit circuit 7 is input to the negative input terminal of the operational amplifier OP2, and is amplified by the operational amplifier OP2 at a predetermined amplification factor. A control voltage, which is a voltage obtained by dividing the voltage by the voltage dividing resistors R12 and R13, is input to the inverter circuit 2.
That is, the lower limiter control voltage set by the dimming lower limiter circuit 7 is output to the inverter circuit side.

As described above, when the control voltage generated by the dimming control voltage generation circuit 5 according to the duty of the dimming signal is lower than the lower limit limiter control voltage set by the dimming lower limiter circuit 7, the inverter is generated by the lower limiter control voltage. Since the ON period of the switching element of the circuit 2 is determined, the luminous flux output of the discharge lamp is held by the lower limiter control voltage even if the duty of the dimming signal is further increased.
As described above, when the ambient temperature is 15 ° C. or higher, the lower limit limiter control voltage set by the dimming lower limit circuit 7 is output to the inverter circuit 2. Is performed, the lower limit control voltage, which is the voltage at the connection point between the thermistor RT1 and the resistor R9, increases due to the temperature characteristics of the thermistor RT1 of the dimming lower limit setting circuit 6.

Then, the increased lower limit control voltage becomes higher than the lower limit limiter control voltage, which is the voltage at the connection point between the resistor R10 and the resistor R11 of the dimming lower limiter circuit 7, so that the operational amplifier OP1 of the dimming control voltage output circuit 8 has so far been Instead of the lower limiter control voltage input to the positive input terminal, the increased lower limit control voltage is input to the positive input terminal of the operational amplifier OP1 of the dimming control voltage output circuit 8 through the diode D6, and is amplified by the operational amplifier OP2. A control voltage, which is a voltage obtained by dividing the voltage amplified by the rate by the voltage dividing resistors R12 and R13, is input to the inverter circuit 2.
That is, the high lower limit control voltage set by the dimming lower limit temperature compensation circuit 6 is output to the inverter circuit 2. Accordingly, when low dimming is performed in which the luminous flux decreases when the ambient temperature is 15 ° C. or lower, the luminous flux output of the discharge lamp is increased, so that the discharge lamp is less likely to flicker.

  The dimming control circuit 4 of the discharge lamp lighting device according to the first embodiment has a dimming that does not have temperature characteristics, separately from the dimming control voltage generation circuit 5 and the dimming lower limit temperature compensation circuit 6 having negative temperature characteristics. The lower limiter circuit 7 is newly provided, and the dimming lower limiter circuit 7 operates at a predetermined temperature or higher including the temperature in the production process of the product and the temperature in the actual use state. Even if the adjustment is performed in the production process, it does not depend on the negative temperature characteristic. Therefore, as shown in FIG. 3B, the adjustment range at the temperature of the production process is the same as the adjustment range at the temperature in the actual use state. As a result, the design in consideration of the production process is facilitated, and the adjustment range can be increased compared with the conventional case, and the adjustment is facilitated.

Embodiment 2. FIG.
4 is a block diagram showing a configuration of a discharge lamp lighting device according to Embodiment 2 of the present invention, FIG. 5 is a circuit diagram showing a configuration of a dimming control circuit of the discharge lamp lighting device, and FIG. 6 has an upper limiter. It is a graph which shows the relationship between input electric power and temperature of a light control lower limit.
In the second embodiment of the present invention, the same components as those in the first embodiment are denoted by the same reference numerals, and the description of the overlapping components is omitted.
The second embodiment is different from the dimming lower limit temperature compensation circuit 6 of the first embodiment in that the dimming lower limit temperature compensation circuit 16 has an upper limiter at the dimming lower limit.
As shown in FIG. 5, the dimming lower limit temperature compensation circuit 16 of the dimming control circuit 4 is provided with a Zener diode DZ2 between the connection point of the resistor 8 and the thermistor RT1 and the line on the ground side.

In the second embodiment, when low dimming is performed in which the luminous flux decreases when the ambient temperature is 15 ° C. or lower, the voltage at the connection point between the thermistor RT1 and the resistor R9 is determined by the temperature characteristics of the thermistor RT1 of the dimming lower limit setting circuit 6. As the lower limit control voltage increases and the ambient temperature decreases, the lower limit control voltage gradually increases.
Therefore, when the ambient temperature falls below a predetermined temperature, the lower limit control voltage, which becomes higher, is clipped by the Zener diode DZ2, and the lower limit control voltage is set as a constant upper limit limiter even if the ambient temperature decreases further. Is input to the positive input terminal of the operational amplifier OP1 of the dimming control voltage output circuit 8, and the lower limit control voltage of the upper limiter, which is a voltage obtained by dividing the voltage of the operational amplifier OP2 by the voltage dividing resistors R12 and R13, is supplied to the inverter circuit 2. It is to be input.

  In the second embodiment, when low dimming is performed in which the luminous flux is reduced when the ambient temperature is 15 ° C. or lower, the constant upper limit is maintained even if the ambient temperature is further decreased when the ambient temperature is lower than a predetermined temperature. Since the lower limit control voltage used as a limiter is output to the inverter circuit 2, in order to prevent flickering of the discharge lamp up to a predetermined dimming lower limit / low temperature, a negative temperature characteristic is provided to increase power. However, if the power at the lower limit of dimming is increased more than necessary, the power saving effect, which is the original purpose of dimming, is impaired at low temperatures. When it becomes, it suppresses that electric power goes up more than necessary and maintains the effect of power saving.

The block diagram which shows the structure of the discharge lamp lighting device which concerns on Embodiment 1 of this invention. The circuit diagram which shows the structure of the light control circuit of the discharge lamp lighting device. (A) is a graph which shows the relationship between a light control lower limit, input electric power, and temperature, (b) is a graph which shows the relationship between the adjustment range of light control lower limit, and temperature. The block diagram which shows the structure of the discharge lamp lighting device which concerns on Embodiment 2 of this invention. The circuit diagram which shows the structure of the light control circuit of the discharge lamp lighting device. The graph which shows the relationship between the light control lower limit which has an upper limiter, input power, and temperature.

Explanation of symbols

  1 DC power supply, 2 inverter circuit, 3 load circuit, 4 dimming control circuit, 5 dimming control voltage generating circuit, 6 dimming lower limit temperature compensation constant circuit, 7 dimming lower limit limiter circuit, LS dimming signal.

Claims (4)

An inverter circuit for converting a DC voltage into a high-frequency voltage;
A load circuit for supplying an alternating voltage generated from the inverter circuit to the discharge lamp;
A discharge lamp lighting device having a dimming control circuit for driving and controlling the inverter circuit by a dimming control voltage of the discharge lamp generated based on a dimming signal,
The dimming control circuit includes:
Dimming control voltage generating means for generating a DC voltage whose voltage value linearly decreases as the pulse width of the dimming signal increases, and outputting this as a dimming control voltage for the discharge lamp to the inverter circuit side;
A negative temperature characteristic that generates a lower limit control voltage that sets the lower limit of the dimming range of the discharge lamp below a predetermined temperature and outputs the lower limit control voltage to the inverter circuit side when the control voltage falls below the lower limit control voltage Dimming lower limit temperature compensation means having
Dimming that generates a lower limiter control voltage that sets the lower limit of the dimming range of the discharge lamp above a predetermined temperature and outputs the lower limiter control voltage to the inverter circuit side when the control voltage falls below the lower limit control voltage A lower limiter means;
A discharge lamp lighting device comprising:   The dimming lower limit temperature compensation means generates the lower limit control voltage based on voltage division by a plurality of impedance elements to which a predetermined voltage is applied, and at least one of the plurality of impedance elements is a thermistor. The discharge lamp lighting device according to claim 2, wherein:   3. The discharge lamp lighting device according to claim 1, wherein the dimming lower limit temperature compensating means includes upper limit limiter means for clipping the lower limit control voltage to a constant voltage below a predetermined temperature. The discharge lamp lighting device according to claim 3, wherein the upper limiter means of the dimming lower limit temperature compensation means is at least a Zener diode connected in parallel to the thermistor.

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