JP2009262672A - Lighting circuit for discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting circuit for a discharge lamp capable of maintaining lighting of the discharge lamp, even if power generation amount becomes lower than rated power, without lowering rated power of the discharge lamp for a headlamp. <P>SOLUTION: This lighting circuit 16 for the discharge lamp is provided with a power monitoring circuit 26 for detecting a driving circuit supply power value DV supplied from a power generator 12 for a vehicle, a reference value arithmetic circuit 28 for outputting a rated power value SV as a reference power value BV when the driving circuit supply power value DV is a rated power value SV of the discharge lamp 18 or more and outputting the reference power value BV which is equal to the driving circuit supply power value DV or lower than the driving circuit supply power value DV when the driving circuit supply power value DV is lower than the rated power value SV, and a differential output device 30 for comparing the reference power value BV with a discharge lamp supply power value IV supplied from a constant power supply circuit 32 to the discharge lamp 18 and outputting a power reduction signal RS or a power increase signal IS to the constant power supply circuit 32. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting circuit for lighting a discharge lamp used for a headlamp of a vehicle such as an automobile or a motorcycle.

  Incandescent bulbs represented by halogen lamps have been used for the headlamps of vehicles such as automobiles and motorcycles. Recently, however, the use of discharge lamps has become popular for higher brightness. .

  Since this discharge lamp emits light by generating an arc discharge between a pair of electrodes arranged apart from each other, a low voltage (12V or 24V) supplied from a generator mounted on the vehicle is used. In contrast to halogen lamps that emit light simply by supplying them as they are, discharge lamps must be supplied with a higher voltage than halogen lamps. In particular, at the start of lighting, it is necessary to supply a high voltage of several tens of kV in order to cause dielectric breakdown between the electrodes. For this reason, in order to use a discharge lamp for a vehicle headlamp, it is indispensable not only to replace a halogen lamp with a discharge lamp, but also to mount a discharge lamp lighting circuit. , An igniter that generates the high voltage required at the start of discharge lamp lighting, and a constant power supply circuit that is constantly used during the lighting of the discharge lamp, including at the start, and controls the power supplied to the discharge lamp at a constant level ing.

  By the way, the electric power to the discharge lamp lighting circuit is supplied from the generator as described above. However, the generator mounted on a commercially available vehicle has a halogen lamp because of the demand for cost reduction and weight reduction. In many cases, it has only the minimum necessary ability to maintain the lighting state. For this reason, for example, in the case of a two-wheeled vehicle in which one halogen lamp with a rating of 20 W is mounted on the headlamp as standard equipment, when the engine speed is high as in normal driving, power of 20 W or more is generated, The halogen lamp is lit at the rated power. However, when the engine is idling while the vehicle is stopped, such as waiting for a signal, and the engine speed is low, the amount of generated power is less than 20 W (for example, about 10 W), and the halogen lamp uses a filament. Lights up in the “low light” state.

  Thus, in the case of a halogen lamp, even if the amount of generated power is less than the rated power, the amount of light is reduced and the lamp is not turned off. However, the constant power supply circuit used in the discharge lamp lighting circuit includes the rated power of the discharge lamp (including not only the rated power of the discharge lamp but also the internal power loss of the constant power supply circuit and the igniter itself, the same applies hereinafter). If the input power is lower than that, it is judged to be “abnormal” and the power supply to the discharge lamp is stopped. In combination with the fact that it takes a long time to turn on, it becomes an unsafe state especially during night driving.

  Therefore, a vehicular lighting device has been developed that can continue illumination with a headlamp even when the amount of power generation is low, such as during idling (eg, Patent Document 1). As shown in FIG. 4, the vehicle lighting device 1 of Patent Document 1 includes a discharge lamp 3 and an auxiliary lamp 4 housed in a headlamp 2, a lighting circuit 5 that supplies power to the discharge lamp 3, and a discharge lamp. It comprises a relay 6 that forms a closed circuit for operating to supply power to the auxiliary lamp 4 when it detects that the lamp 3 has been turned off.

According to this vehicular lighting device 1, when the amount of power generated by the generator 7 becomes low and it is detected that the discharge lamp 3 attached to the headlamp 2 is extinguished, the relay 6 is activated and replaced with the discharge lamp 3. By turning on the auxiliary lamp 4, the illumination by the headlamp 2 can be maintained.
JP 2007-253899 A

  However, the vehicular lighting device 1 of Patent Document 1 only admits that the discharge lamp 3 is extinguished when the amount of power generated by the generator 7 becomes low in the first place, and only maintains the illumination by the headlamp 2. For this purpose, the alternative auxiliary lamp 4 is turned on, and this is not a fundamental solution to the problem of “the discharge lamp is extinguished”. Further, in the vehicular lighting device 1, the auxiliary lamp 4 must be accommodated in addition to the discharge lamp 3 in the headlamp 2, so the headlamp 2 is enlarged by the amount of the auxiliary lamp 4, and the headlamp There is another problem that the degree of freedom of shape 2 is cut.

  Further, if the rated power of the discharge lamp is set to the idling power generation amount (10 W in the above example) separately from the vehicle lighting device 1, the discharge lamp can be avoided from being turned off. In this case, only 10 W of light can be emitted even during normal driving, and as described above, if a 20 W rated halogen lamp is replaced with a 10 W rated discharge lamp, the merit will be lost. .

  The present invention has been developed in view of such problems of the prior art. Therefore, the main problem of the present invention is to maintain the lighting of the discharge lamp without reducing the rated power of the discharge lamp attached to the headlamp, even when the amount of power generated by the vehicle generator is lower than the rated power. Another object is to provide a lighting circuit for a discharge lamp.

The invention described in claim 1 is “a DC power supply circuit 22 that is connected to the vehicle generator 12 and converts an AC current supplied from the vehicle generator 12 into a DC current;
A constant power supply circuit 32 that is connected to the DC power supply circuit 22 and supplies power to the discharge lamp 18 attached to the headlamp 14 of the vehicle. A high voltage is applied to the discharge lamp 18 in the extinguished state to start lighting. An igniter 34 and a drive circuit 24 having a lamp power monitoring circuit 36 for detecting a discharge lamp supply power value IV supplied from the constant power supply circuit 32 to the discharge lamp 18;
A power monitoring circuit 26 connected to the DC power supply circuit 22 for detecting a drive circuit supply power value DV supplied from the DC power supply circuit 22 to the drive circuit 24;
The drive circuit supply power value DV connected to the power monitoring circuit 26 and received from the power monitoring circuit 26 is the rated power value SV of the discharge lamp 18 (in this specification, “rated power of the discharge lamp” In this case, the rated power value SV is output as the reference power value BV, and the drive circuit supply power is supplied. A reference value calculation circuit 28 that outputs a reference power value BV that is equal to or lower than the drive circuit supply power value DV when the value DV is less than the rated power value SV;
Connected to the lamp power monitoring circuit 36 and the reference value calculation circuit 28, the reference power value BV is compared with the discharge lamp supply power value IV, and the discharge lamp supply power value IV is greater than the reference power value BV. It is constituted by a differential output device 30 that outputs a power decrease signal RS to the constant power supply circuit 32 when large, and outputs a power increase signal IS to the constant power supply circuit 32 when small. This is a discharge lamp lighting circuit 16 ”.

  According to the discharge lamp lighting circuit 16 according to the present invention, the alternating current generated by the vehicular generator 12 is converted into a direct current by the direct current power circuit 22, and the amount of power is converted by the constant power supply circuit 32 of the drive circuit 24. (The adjustment of the electric energy will be described later), and then supplied to the discharge lamp 18 attached to the headlamp 14. When the discharge lamp 18 is turned on, a high voltage is applied to the discharge lamp 18 by the igniter 34. The high voltage causes dielectric breakdown between the electrodes of the discharge lamp 18, thereby starting the discharge lamp 18.

  After the discharge lamp 18 is turned on, when the engine speed is high as in normal driving and the electric power exceeding the rated power value SV of the discharge lamp 18 is generated by the vehicle generator 12, the power monitoring circuit 26 The drive circuit supply power value DV detected by the reference value calculation circuit 28 and output to the reference value calculation circuit 28 is equal to or higher than the rated power value SV of the discharge lamp 18, so the reference value calculation circuit 28 calculates the rated power value SV of the discharge lamp 18. It outputs to the differential output device 30 as “reference power value BV”. Upon receiving this reference power value BV (= rated power value SV of the discharge lamp 18), the differential output device 30 supplies the discharge lamp supply power value IV (lamp power monitoring circuit) supplied from the constant power supply circuit 32 to the discharge lamp 18. 36) and the reference power value BV, and the constant power supply circuit 32 is instructed so that the discharge lamp supply power value IV matches the reference power value BV. That is, the differential output device 30 outputs the power decrease signal RS to the constant power supply circuit 32 when the discharge lamp supply power value IV is larger than the reference power value BV, and conversely, when it is small, the differential output device 30 outputs the power increase signal IS. Output. As a result, the rated power of the discharge lamp 18 is supplied from the constant power supply circuit 32 to the discharge lamp 18, and the discharge lamp 18 emits light at the rated power.

  On the other hand, when the engine speed is low and the amount of power generated by the vehicular generator 12 is lower than the rated power value SV of the discharge lamp 18 as during idling, it is detected by the power monitoring circuit 26 and output to the reference value calculation circuit 28. Since the drive circuit supply power value DV is lower than the rated power value SV of the discharge lamp 18, the reference value calculation circuit 28 is equal to the drive circuit supply power value DV or lower than the drive circuit supply power value DV. The value is output to the differential output unit 30 as “reference power value BV”.

  Various methods are conceivable for setting the “reference power value BV” when the power generation amount is lower than the rated power value SV of the discharge lamp 18. For example, as shown in A of FIG. A method of setting the reference power value BV to be directly proportionally smaller as DV becomes smaller can be mentioned. When this method is used, the reference power value BV becomes equal to the drive circuit supply power value DV. Of course, it is not directly proportional, and may be set as a parabola as shown by B in FIG. 2, or may be set stepwise as shown in FIG. 3 (the step is limited to a specific number of stages). Not.) When the reference power value BV is set parabolically or stepwise (digitally), the reference power value BV is basically set lower than the drive circuit supply power value DV. Further, in this case, when the drive circuit supply power value DV is continuously reduced, the reference power value BV may be drastically reduced (for example, a portion in B in FIG. 2 or in FIG. 3). 2), even if the reference power value BV decreases rapidly and the discharge lamp supply power value IV decreases rapidly, the brightness of the discharge lamp 18 is higher than the speed at which the discharge lamp supply power value IV decreases. The rate of decrease is slower, and the brightness of the discharge lamp 18 gradually decreases (that is, the decrease in brightness of the discharge lamp 18 is directly proportional). For this reason, compared with the case where the reference power value BV is set to be directly proportionally smaller, the reduction in brightness of the discharge lamp 18 is equivalent to the case where the reference power value BV is set to be directly proportionally smaller while keeping the power consumption low. Can be.

  The differential output device 30 receiving this reference power value BV (= a power value equal to or lower than the drive circuit supply power value DV) receives the reference power value BV and the discharge lamp supply power value IV. And, as described above, the constant power supply circuit 32 is instructed so that the discharge lamp supply power value IV matches the reference power value BV. As a result, power corresponding to the drive circuit supply power value DV is supplied from the constant power supply circuit 32 to the discharge lamp 18, and the amount of light is reduced as compared with the case where the rated power is received, but the discharge lamp 18 is turned on. The state can be maintained (of course, the discharge lamp 18 is used that can be lit with a rated power value SV and a power lower than the rated power value SV).

  The above-mentioned “power value” measures at least a voltage value or a current value (for example, if the drive circuit supply power value is DV, measures at least one of a voltage value or a current value in the DC power supply circuit 22), Or the value obtained from the product of both. For this reason, instead of the “power value”, the constant power supply circuit 32 may be controlled using a voltage value or a current value, and the lighting state of the discharge lamp 18 may be maintained.

The invention according to claim 2 relates to the discharge lamp lighting circuit 16 according to claim 1, “The extinction power value OV lower than the rated power value SV is preset in the reference value calculation circuit 28,
The reference value calculation circuit 28 outputs a turn-off signal OS to the differential output unit 30 when the drive circuit supply power value DV is lower than the turn-off power value OV.
The differential output device 30 that has received the extinguishing signal OS outputs a stop signal SS for stopping the power supply to the discharge lamp 18 to the constant power supply circuit 32 ”.

  According to the present invention, when the drive circuit supply power value DV is lower than the “light-off power value OV” preset in the reference value calculation circuit 28, the light-off signal OS is sent from the reference value calculation circuit 28 to the differential output device 30. The differential output device 30 receiving this extinguishing signal OS outputs a stop signal SS to the constant power supply circuit 32.

  Thus, for example, the value of power generated by the vehicle generator 12 when the engine speed is low, such as during idling, or the lower limit power value at which the discharge lamp 18 can remain lit, such as “less than the rated power value SV. By setting the “low extinction power value OV” in advance, when the drive circuit supply power value DV falls below the “extinguishing power value OV” due to an abnormality of the vehicle generator 12 or the like, the electric power is supplied to the discharge lamp 18. Since it stops and the discharge lamp 18 is extinguished, the user of the vehicle can know the abnormality of the vehicle generator 12 without delay.

  According to the present invention, when the amount of power generated by the vehicular generator is smaller than the rated power of the discharge lamp, the power value corresponding to the power generation amount is equal to or lower than the drive circuit supply power value. By operating the constant power supply circuit of the drive circuit with the reference power value as the reference power value, it is possible to reduce the rated power of the discharge lamp without reducing the rated power of the discharge lamp, even if the amount of power generated by the vehicle generator is lower than the rated power. A lighting circuit for a discharge lamp capable of maintaining lighting can be provided.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. The vehicle lighting device 10 according to this embodiment is applied to a vehicle such as an automobile, a two-wheeled vehicle, a snowmobile, or a water motorcycle. For example, as shown in FIG. 14 and a discharge lamp lighting circuit 16.

  The vehicular generator 12 receives a part of the engine power and generates power for the headlamp 14, power for in-vehicle lighting, and the like.

  The headlamp 14 is mounted at a predetermined position in the vehicle and illuminates the traveling direction of the vehicle, and a discharge lamp 18 as a light source and a reflecting mirror that reflects light emitted from the discharge lamp 18 in a desired direction. 20.

  The discharge lamp lighting circuit 16 has a circuit configuration as shown in FIG. 1, and includes a DC power supply circuit 22, a drive circuit 24, a power monitoring circuit 26, a reference value calculation circuit 28, and a differential output device 30. It is configured.

  The DC power supply circuit 22 is a bridge circuit connected to the vehicle generator 12 and full-wave rectifies the AC current supplied from the vehicle generator 12, and is further smoothed by, for example, a smoothing capacitor (not shown). It converts to direct current.

  The drive circuit 24 includes a constant power supply circuit 32, an igniter 34, and a lamp power monitoring circuit 36.

  The constant power supply circuit 32 includes a PWM converter 38, which performs pulse width modulation control on the DC current supplied from the DC power supply circuit 22 in accordance with the signal from the PWM converter 38, and smoothes and outputs it. It is.

  The PWM converter 38 receives a power reduction signal RS or a power increase signal IS from a differential output device 30 described later, and performs pulse width modulation control, thereby supplying the discharge lamp 18 from the constant power supply circuit 32 to the discharge lamp 18. It controls the supply power value IV.

  The igniter 34 is connected to the constant power supply circuit 32, and includes a transformer (not shown) that outputs a high voltage and a trigger (not shown) that inputs a start pulse to the transformer. The igniter 34 is applied to start the lighting by applying a high voltage to the discharge lamp 18 in the off state, and does not operate when the discharge lamp 18 is steadily lit.

  The lamp power monitoring circuit 36 is connected to the constant power supply circuit 32 and detects a discharge lamp supply power value IV supplied from the constant power supply circuit 32 to the discharge lamp 18.

  The power monitoring circuit 26 is connected to the DC power supply circuit 22, detects the drive circuit supply power value DV supplied from the DC power supply circuit 22 to the constant power supply circuit 32 of the drive circuit 24, and outputs it to the reference value calculation circuit 28. Is.

  The reference value calculation circuit 28 sets a reference power value BV based on the drive circuit supply power value DV received from the power monitoring circuit 26, and outputs the reference power value BV to the differential output device 30.

  The setting method of the reference power value BV will be described in detail. When the drive circuit supply power value DV received from the power monitoring circuit 26 is equal to or higher than the rated power value SV of the discharge lamp 18, the reference value calculation circuit 28 The rated power value SV is set as the reference power value BV.

  Conversely, when the drive circuit supply power value DV is lower than the rated power value SV of the discharge lamp 18, the reference value calculation circuit 28 uses a value equal to the drive circuit supply power value DV as a reference, as indicated by A in FIG. The power value BV is set (that is, the reference power value BV is set to be directly proportionally smaller as the drive circuit supply power value DV becomes smaller). As described above, the setting method of the reference power value BV in the case where the drive circuit supply power value DV is lower than the rated power value SV of the discharge lamp 18 is not limited to this, and as indicated by B in FIG. It may be set parabolically or stepwise as shown in FIG.

  In addition, the reference value calculation circuit 28 is preset with a turn-off power value OV lower than a power value generated when the engine speed is low, for example, and the drive circuit supply power value DV is turned off. The reference value calculation circuit 28 outputs a turn-off signal OS to the differential output device 30 when the value is less than.

  The differential output device 30 (FIG. 1) is connected to the lamp power monitoring circuit 36 and the reference value calculation circuit 28, and the discharge lamp supply power value IV output from the lamp power monitoring circuit 36 and the reference value calculation circuit 28. When the discharge lamp supply power value IV is larger than the reference power value BV, the power reduction signal RS is output to the PWM converter 38 of the constant power supply circuit 32. When the discharge lamp supply power value IV is smaller than the reference power value BV, the power increase signal IS is output to the PWM converter 38. When receiving the turn-off signal OS from the reference value calculation circuit 28, the differential output device 30 outputs a stop signal SS for stopping the power supply to the discharge lamp 18 to the PWM converter 38 of the constant power supply circuit 32. .

  Start the vehicle engine and turn on the unillustrated headlamp lighting switch (note that the headlamps are always lit on modern motorcycles, and the headlamp lights up just by starting the engine. The AC power generated by the vehicle generator 12 is converted into a DC current by the DC power supply circuit 22, and this DC current is adjusted by the constant power supply circuit 32 of the drive circuit 24. Is output to the igniter 34. After the high voltage start pulse is applied in the igniter 34, the direct current is supplied to the discharge lamp 18 in the headlamp 14.

  In the discharge lamp 18 to which a direct current to which a high-voltage start pulse has been added is supplied, dielectric breakdown occurs between the electrodes, and then arc discharge occurs through glow discharge, and the discharge lamp 18 shifts to steady lighting. After the discharge lamp 18 shifts to arc discharge, the igniter 34 stops and the start pulse addition to the direct current is completed.

  After the discharge lamp 18 is turned on, when the rotational speed of the engine is high as in normal running and the electric power exceeding the rated power of the discharge lamp 18 is generated by the vehicle generator 12, as described above, Since the drive circuit supply power value DV detected by the monitoring circuit 26 and output to the reference value calculation circuit 28 is equal to or higher than the rated power value SV of the discharge lamp 18, the reference value calculation circuit 28 determines the rated power of the discharge lamp 18. The value SV is output to the differential output unit 30 as the “reference power value BV”. Upon receiving this reference power value BV (= rated power value SV of the discharge lamp 18), the differential output device 30 supplies the discharge lamp supply power value IV (lamp power monitoring circuit) supplied from the constant power supply circuit 32 to the discharge lamp 18. 36) and the reference power value BV are compared, and an instruction is given to the PWM converter 38 of the constant power supply circuit 32 so that the discharge lamp supply power value IV matches the reference power value BV. That is, when the discharge lamp supply power value IV is larger than the reference power value BV, the power reduction signal RS is output to the PWM converter 38, and conversely, when the discharge lamp supply power value IV is smaller than the reference power value BV. The power increase signal IS is output to the PWM converter 38. As a result, the rated power of the discharge lamp 18 is supplied from the constant power supply circuit 32 to the discharge lamp 18, and the discharge lamp 18 emits light at the rated power.

  On the other hand, when the engine speed is low and the amount of power generated by the vehicular generator 12 is smaller than the rated power of the discharge lamp 18 as during idling, it is detected by the power monitoring circuit 26 and output to the reference value calculation circuit 28. Since the drive circuit supply power value DV is lower than the rated power value SV of the discharge lamp 18, the reference value calculation circuit 28 sets a value equal to the drive circuit supply power value DV as indicated by A in FIG. The value is set as the value BV (that is, the reference power value BV is set to be proportionally smaller as the drive circuit supply power value DV becomes smaller), and the reference power value BV is output to the differential output device 30.

  Upon receiving this reference power value BV (= power value lower than the rated power value SV of the discharge lamp 18), the differential output device 30 compares the reference power value BV with the discharge lamp supply power value IV, as described above. In addition, the PWM converter 38 is instructed so that the discharge lamp supply power value IV matches the reference power value BV.

  As a result, power corresponding to the drive circuit supply power value DV is supplied from the constant power supply circuit 32 to the discharge lamp 18, and the amount of light is reduced as compared with the case where the rated power is received. The lighting state of can be maintained.

  In addition, when the drive circuit supply power value DV falls below the extinction power value OV which is preset in the reference value calculation circuit 28 and is lower than the power value generated when the engine speed is low, the reference value calculation circuit 28 outputs a turn-off signal OS to the differential output unit 30. Upon receiving the turn-off signal OS, the differential output unit 30 outputs a stop signal SS to the PWM converter 38.

  As a result, when the drive circuit supply power value DV falls below the extinguishing power value OV due to an abnormality of the vehicle generator 12, etc., the power supply to the discharge lamp 18 is stopped and the discharge lamp 18 is extinguished. Can know the abnormality without delay.

  The above-mentioned “power value” measures at least a voltage value or a current value (for example, if the drive circuit supply power value is DV, measures at least one of a voltage value or a current value in the DC power supply circuit 22), Or the value obtained from the product of both. For this reason, instead of the “power value”, the constant power supply circuit 32 may be controlled using a voltage value or a current value, and the lighting state of the discharge lamp 18 may be maintained.

It is a figure which shows the lighting circuit for discharge lamps concerning this invention. It is a graph which shows an example of the relationship between a drive circuit supply electric power value and a reference | standard electric power value. It is a graph which shows the other example of the relationship between a drive circuit supply electric power value and a reference electric power value. It is a figure which shows a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vehicle lighting device 12 ... Vehicle generator 14 ... Headlamp 16 ... Discharge lamp lighting circuit 18 ... Discharge lamp 20 ... Reflector 22 ... DC power supply circuit 24 ... Drive circuit 26 ... Power monitoring circuit 28 ... Reference value Arithmetic circuit 30 ... differential output device 32 ... constant power supply circuit 34 ... igniter 36 ... lamp power monitoring circuit 38 ... PWM converter

Claims (2)

A direct-current power supply circuit connected to the vehicular generator and converting an alternating current supplied from the vehicular generator into a direct current;
A constant power supply circuit that is connected to the DC power supply circuit and supplies power to a discharge lamp attached to a headlamp of a vehicle, an igniter that starts lighting by applying a high voltage to the discharge lamp that is turned off, and the constant A drive circuit having a lamp power monitoring circuit for detecting a discharge lamp supply power value supplied from the power supply circuit to the discharge lamp;
A power monitoring circuit connected to the DC power supply circuit for detecting a drive circuit supply power value supplied from the DC power supply circuit to the drive circuit;
When the drive circuit supply power value received from the power monitoring circuit is greater than or equal to the rated power value of the discharge lamp, connected to the power monitoring circuit, the rated power value is output as a reference power value, and the drive circuit A reference value calculation circuit that outputs a reference power value equal to or lower than the drive circuit supply power value when the supply power value is lower than the rated power value;
The lamp power monitoring circuit and the reference value calculation circuit are connected to compare the reference power value with the discharge lamp supply power value, and when the discharge lamp supply power value is larger than the reference power value, a power reduction signal And a differential output device that outputs a power increase signal to the constant power supply circuit when it is small. In the reference value calculation circuit, a turn-off power value lower than the rated power value is preset,
When the drive circuit supply power value is lower than the extinction power value, the reference value calculation circuit outputs an extinction signal to the differential output device,
2. The discharge lamp lighting circuit according to claim 1, wherein the differential output device that has received the turn-off signal outputs a stop signal for stopping power supply to the discharge lamp to the constant power supply circuit. .

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