JP2015056229A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device that can suppress reduction of the lifetime of a light source under such abnormality that an input voltage decreases.SOLUTION: A lighting device has a lighting circuit 1 for performing a power supply operation of supplying power to a discharge lamp La1, an input voltage detector 8 for detecting the input voltage Vin of the lighting circuit 1, a timer 26 for counting a time for which the input voltage Vin is lower than an operation keeping voltage V1, an operation control circuit 25 for starting the power supply operation of the lighting circuit 1 when the input voltage Vin is not less than an operation allowance voltage V2, stops the power supply operation when the time count result of the timer 26 reaches a determination time, and re-starts the power supply operation when the input voltage Vin is equal to the operation allowance voltage V2 or more again, and a counter 27 for counting a stop frequency at which the operation control circuit 25 stops the power supply operation. The operation control circuit 25 extends the determination time so that the determination time is longer than a determination time used for previous determination processing when the count frequency of the counter 27 reaches a predetermined frequency.

Description

  The present invention relates to a lighting device.

  Conventionally, there is a lighting device that turns on a light source using an external power source. In addition, when hysteresis is set for the input voltage, power supply to the light source is started when the input voltage exceeds the operation permission voltage, and power supply to the light source is started when the input voltage becomes lower than the operation maintenance voltage lower than the operation permission voltage. There exists a lighting device which stops (for example, refer to patent documents 1). When the input voltage momentarily falls below the operation maintenance voltage, the lighting device continues power supply to the light source. Stop supplying.

  Here, when power is supplied to the light source by operating the lighting device in the state where the internal impedance of the external power source or the line impedance between the external power source and the lighting device is increased, the input voltage fluctuates. Causes the light source to flash. 12A is a waveform diagram of the power supply voltage of the external power supply, FIG. 12B is a waveform diagram of the input current of the lighting device, FIG. 12C is a waveform diagram of the input voltage of the lighting device, and FIG. Shows the judgment result of operation permission / stop.

  As shown in FIG. 12, when the input voltage becomes equal to or higher than the operation permission voltage and power supply to the light source is started, the input current increases. However, when the input current increases, the input voltage is greatly reduced due to the abnormality. When the time when the input voltage falls below the operation maintaining voltage becomes equal to or longer than the determination time, the power supply to the light source is stopped and the light source is turned off. Since the input current is reduced by turning off the light source, the input voltage rises and becomes equal to or higher than the operation permission voltage again, and the light source is turned on again. However, since the input current increases when the light source is turned on again, the input voltage decreases again and the light source is turned off. As described above, when an abnormality occurs in which the input voltage decreases, the light source repeats blinking.

JP 2011-91014 A

  However, there is a problem in that the life of the light source is reduced due to repeated blinking of the light source at the time of an abnormality in which the input voltage decreases.

  The present invention has been made in view of the above-described reasons, and an object of the present invention is to provide a lighting device that can suppress a decrease in the lifetime of a light source in an abnormal time when the input voltage decreases.

  The lighting device of the present invention includes a lighting circuit that performs a power supply operation for supplying power to a light source, an input voltage detection unit that detects an input voltage of the lighting circuit, and the input voltage that is less than a first threshold voltage. A timer that starts timing and stops timing when the voltage exceeds the first threshold voltage; and when the input voltage is equal to or higher than a second threshold voltage that is higher than the first threshold voltage, the lighting circuit When a power supply operation is started and the input voltage becomes less than the first threshold voltage, a determination process is performed to compare the time measurement result of the timer with a determination time, and when the time measurement result of the timer reaches the determination time A control circuit that stops the power supply operation of the lighting circuit and restarts the power supply operation of the lighting circuit when the input voltage again becomes equal to or higher than the second threshold voltage, and a timing result of the timer is determined by the timer. A counter that counts the number of times the control circuit has stopped the power supply operation of the lighting circuit by reaching time, and the control circuit, when the count number of the counter reaches a predetermined number of times, The determination time is made longer than the determination time used in the previous determination process.

  In this lighting device, the control circuit preferably extends the determination time longer than the determination time used in the previous determination process each time the count of the counter increases.

  In this lighting device, it is preferable that the control circuit reduces power supplied to the light source by the lighting circuit when the determination time is longer than a threshold time.

  In this lighting device, when the determination time becomes longer than the threshold time, the control circuit continues the stop state of the power supply operation of the lighting circuit even when the input voltage becomes equal to or higher than the second threshold voltage. It is preferable.

  In this lighting device, the control circuit sets the determination time for each lighting state of the light source, and the determination corresponding to the lighting state of the light source when the count number of the counter reaches the predetermined number of times. It is preferable to extend the time from the previous time.

  In this lighting device, the control circuit preferably extends the determination time beyond the determination time used in the previous determination process when the counter reaches the predetermined number of times that is a plurality of times. .

  In this lighting device, when the count number of the counter reaches the upper limit number, the control circuit continues to stop the power supply operation of the lighting circuit even if the input voltage becomes equal to or higher than the second threshold voltage. It is preferable to make it.

  In this lighting device, it is preferable that the control circuit determines that the steady state is at least when the light source is lit, and resets the count of the counter when the steady state continues for a predetermined time or more. .

  In this lighting device, the control circuit determines that it is in a steady state at least when the light source is turned on, and resets the count number of the counter when the steady state continues for a predetermined time or more. It is preferable to return the time to the initial value.

  In this lighting device, the control circuit determines that the steady state is at least when the light source is lit, and resets the count number of the counter when the steady state continues for a predetermined time or more. It is preferable to shorten the determination time step by step as the state elapses.

  In this lighting device, it is preferable that the control circuit shortens the determination time at a rate corresponding to the magnitude of the input voltage as the steady state elapses.

  In this lighting device, it is preferable that the control circuit determines that the steady state is established when the light source is turned on and the input voltage is equal to or higher than the first threshold voltage.

  In this lighting device, the light source is preferably a discharge lamp.

  In this lighting device, the light source is preferably formed of a light emitting diode.

  As described above, in the present invention, when the time during which the input voltage is less than the first threshold voltage reaches the determination time, the control circuit stops the power supply operation of the lighting circuit. When the number of times that the control circuit stops the power supply operation of the lighting circuit reaches a predetermined number, the determination time is extended, so that when the abnormality occurs that the input voltage decreases and the light source blinks, the light source is turned on. The time will be longer. As a result, the possibility that the input voltage is restored during the determination process and the light source can continue to be turned on is improved, so that the number of times the light source blinks can be reduced, and a reduction in the life of the light source can be suppressed.

It is a circuit block diagram of the lighting device of Embodiment 1 of this invention. It is a flowchart which shows operation | movement same as the above. It is a wave form diagram of an input voltage same as the above. It is a flowchart which shows operation | movement of the modified example same as the above. It is a wave form diagram of the input voltage of the modification same as the above. It is a flowchart which shows operation | movement of the modified example same as the above. It is a flowchart which shows operation | movement of the modified example same as the above. 6 is a flowchart illustrating the operation of the lighting device according to the second embodiment. It is a wave form diagram of an input voltage same as the above. 10 is a flowchart illustrating the operation of the lighting device according to the third embodiment. It is a circuit block diagram of the lighting device of another structure. (A) It is a wave form diagram of the power supply voltage of an external power supply. (B) It is a wave form diagram of input current. (C) It is a waveform diagram of an input voltage. (D) It is a figure which shows the determination result of operation | movement permission / stop.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The circuit block diagram of the lighting device of this embodiment is shown in FIG. The lighting device of the present embodiment is mounted on a vehicle and lights a discharge lamp La1 (light source) that functions as a headlamp by using a DC power source E1 formed of a battery as an input power source. In addition, it is not the meaning which limits the lighting device of this embodiment to the use which lights the headlamp of a vehicle.

  First, the structure of the lighting device of this embodiment is demonstrated. The lighting device of the present embodiment mainly includes a lighting circuit 1 and a control unit 2 that controls the lighting circuit 1.

  The lighting circuit 1 includes a DC-DC conversion circuit 3, an inverter circuit 4, and an igniter circuit 5. Then, the lighting circuit 1 generates power necessary for the discharge lamp La1 from DC power supplied from the DC power supply E1, and performs a power supply operation for supplying the generated power to the discharge lamp La1, thereby performing the discharge lamp La1. Lights up.

  The DC-DC conversion circuit 3 is connected to the DC power supply E1 via a switch SW1 that conducts and cuts off the power supply path, and converts the DC input voltage Vin to a voltage level required by the discharge lamp La1. Specifically, the DC-DC conversion circuit 3 includes a transformer T1, a switching element Q1, a diode D1, and a smoothing capacitor C1. The primary winding n1 of the transformer T1 and the switching element Q1 are connected in series, and are connected between the output terminals of the DC power supply E1 via the switch SW1. A series circuit of a diode D1 and a capacitor C1 is connected between both ends of the secondary winding n2 of the transformer T1. Switching of the switching element Q1 is controlled by the control unit 2. When the switching element Q1 is turned on, a DC input current Iin supplied from the DC power supply E1 flows through the primary winding n1, and energy is stored in the transformer T1. When the switching element Q1 is turned off, the energy accumulated in the transformer T1 is supplied from the secondary winding n2 to the capacitor C1. With the above configuration, the DC-DC conversion circuit 3 converts the input voltage Vin to a voltage level required by the discharge lamp La1 by the controller 2 driving the switching element Q1 on and off.

  The inverter circuit 4 converts the DC voltage output from the DC-DC conversion circuit 3 into an AC voltage and outputs the AC voltage to the discharge lamp La1. Specifically, the inverter circuit 4 is configured by a full bridge circuit including switching elements Q2 to Q5. A series circuit of switching elements Q2 and Q4 and a series circuit of switching elements Q3 and Q5 are connected in parallel with the capacitor C1. An output end of the inverter circuit 4 is configured by a connection midpoint between the switching elements Q2 and Q4 and a connection midpoint between the switching elements Q3 and Q5, and the discharge lamp La1 is connected between the output ends. Switching elements Q <b> 2 to Q <b> 5 are switching-controlled by control unit 2. With the above configuration, the inverter circuit 4 causes the output polarity of the DC-DC conversion circuit 3 to be changed by the control unit 2 being alternately turned on / off by the switching elements Q2 and Q5 and the switching elements Q3 and Q4. It is inverted to generate a rectangular wave AC voltage. Then, the inverter circuit 4 turns on the discharge lamp La1 by applying an AC voltage to the discharge lamp La1.

  The discharge lamp La1 is a high-pressure discharge lamp, and an igniter circuit 5 for starting discharge by applying a high voltage to the discharge lamp La1 is connected between the inverter circuit 4 and the discharge lamp La1. . The igniter circuit 5 includes a capacitor Cs1, a transformer T2, and a spark gap SG1. A capacitor Cs1, a series circuit of the primary winding n11 of the transformer T2, and the spark gap SG1, and a series circuit of the secondary winding n12 of the transformer T2 and the discharge lamp La1 are connected in parallel between the output terminals of the inverter circuit 4. . When starting the discharge lamp La1 from the extinguished state (the state between the terminals of the discharge lamp La1 is open), the control unit 2 maintains the switching elements Q2 and Q5 in the on state and the switching elements Q3 and Q4 in the off state to perform switching. The element Q1 is turned on / off. As a result, when the voltage across the capacitor Cs1 rises and exceeds a predetermined voltage, the spark gap SG1 breaks down. When the spark gap SG1 breaks down, a high voltage is applied to the discharge lamp La1 to cause dielectric breakdown, and the discharge lamp La1 is started. After the discharge lamp La1 is started, the lighting of the discharge lamp La1 is continued by applying an AC voltage from the inverter circuit 4.

  The lighting device of the present embodiment includes a voltage detection circuit 6 that detects a lamp voltage applied to the discharge lamp La1, and a current detection circuit 7 that detects a lamp current supplied to the discharge lamp La1. The voltage detection circuit 6 includes a series circuit of resistors R1 and R2 connected between the output terminals of the DC-DC conversion circuit 3, and detects the output voltage Vo of the DC-DC conversion circuit 3, thereby The voltage is detected equivalently. The current detection circuit 7 includes a resistor R3 inserted in the current supply path between the DC-DC conversion circuit 7 and the inverter circuit 4, and detects the output current Io of the DC-DC conversion circuit 3. Thus, the lamp current is detected equivalently.

  Next, the control unit 2 will be described. The control unit 2 includes an output control circuit 21 and a drive circuit 22 that feedback control the output of the DC-DC conversion circuit 3 using the detection values of the voltage detection circuit 6 and the current detection circuit 7. The output control circuit 21 sets a PWM (Pulse Width Modulation) condition of the switching element Q1 based on the detection values of the voltage detection circuit 6 and the current detection circuit 7 in order to set the output of the DC-DC conversion circuit 3 to a desired value. A setting signal to be generated is generated and output to the drive circuit 22. The drive circuit 22 outputs the PWM signal generated based on the setting signal from the output control circuit 21 to the switching element Q1 via the AND circuit 23, thereby driving the switching element Q1 on and off. With the above configuration, the output control circuit 21 and the drive circuit 22 control the power supplied to the discharge lamp La1 by feedback control of the output of the DC-DC conversion circuit 3, thereby stably lighting the discharge lamp La1. The control unit 2 includes a bridge drive circuit 24 that performs switching control of the switching elements Q <b> 2 to Q <b> 5 of the inverter circuit 4.

  Further, the lighting device of the present embodiment includes an input voltage detection unit 8 that detects the input voltage Vin of the lighting circuit 1. The control unit 2 drives / stops the DC-DC conversion circuit 3 and the inverter circuit 4 based on the detection result of the input voltage detection unit 8, that is, an operation control circuit that executes / stops the power supply operation of the lighting circuit 1. 25. The operation control circuit 25 corresponds to the control circuit of the present invention.

  In the operation control circuit 25, an operation maintaining voltage V1 (first threshold voltage) and an operation permission voltage V2 (second threshold voltage) higher than the operation maintaining voltage V1 are set in advance. Then, the operation control circuit 25 compares the input voltage Vin with the operation maintaining voltage V1 and the operation permission voltage V2, and transmits an instruction signal to the AND circuit 23 and the bridge drive circuit 24 based on the comparison result, thereby causing the DC− The DC conversion circuit 3 and the inverter circuit 4 are driven or stopped. Specifically, the operation control circuit 25 starts the power supply operation of the lighting circuit 1 (drive of the DC-DC conversion circuit 3 and the inverter circuit 4) when the input voltage Vin is equal to or higher than the operation permission voltage V2. Then, when the input voltage Vin is equal to or higher than the operation maintaining voltage V1, the operation control circuit 25 continues the power supply operation of the lighting circuit 1 (driving the DC-DC conversion circuit 3 and the inverter circuit 4). Here, immediately after the start of driving of the DC-DC conversion circuit 3 and the inverter circuit 4, the difference in the input current Iin is larger than that immediately before it, and the internal impedance of the DC power supply E1 and the line impedance between the DC power supply E1 and the lighting device As a result, a voltage drop occurs in the input voltage Vin. Therefore, a hysteresis width is set between the operation permission voltage V2 and the operation maintaining voltage V1.

  When an instantaneous drop occurs in the input voltage Vin and the input voltage Vin instantaneously falls below the operation maintaining voltage V1, the driving of the DC-DC conversion circuit 3 and the inverter circuit 4 is continued, and the discharge lamp La1 It is desirable to maintain lighting. Therefore, the control unit 2 includes a timer 26. The timer 26 starts timing when the input voltage Vin becomes less than the operation maintaining voltage V1, and stops counting when the input voltage Vin becomes equal to or higher than the operation maintaining voltage V1. That is, the timer 26 measures the time during which the input voltage Vin is lower than the operation maintaining voltage V1. Then, the operation control circuit 25 performs a determination process for comparing the time measurement result of the timer 26 with the determination time. When the time measurement result of the timer 26 reaches the determination time, the power supply operation of the lighting circuit 1 is stopped (DC-DC). The conversion circuit 3 and the inverter circuit 4 are stopped), and the discharge lamp La1 is turned off. With the above configuration, even when an instantaneous drop occurs in the input voltage Vin, the operations of the DC-DC conversion circuit 3 and the inverter circuit 4 can be continued and the lighting of the discharge lamp La1 can be maintained. The timer 26 resets the time measurement result when the input voltage Vin becomes equal to or higher than the operation maintaining voltage V1.

  Here, when an abnormality occurs in which the internal impedance of the DC power supply E1 or the line impedance increases, the abnormality may cause the input voltage Vin to be greatly reduced to become less than the operation maintaining voltage V1, and the discharge lamp La1 may be turned off. However, since the discharge lamp La1 is extinguished, the load viewed from the DC power supply E1 is reduced (the input current Iin is reduced). Therefore, the input voltage Vin may be restored (increased) and become the operation permission voltage V2 or more again. is there. In this case, the operation control circuit 25 restarts the power supply operation of the lighting circuit 1 (drive of the DC-DC conversion circuit 3 and the inverter circuit 4), and relights the discharge lamp La1. However, when the discharge lamp La1 is turned on again and the input voltage Vin decreases again to become less than the operation maintaining voltage V1, the discharge lamp La1 is turned off again. That is, the discharge lamp La1 repeats blinking.

  However, when the discharge lamp La1 repeats blinking, the life of the discharge lamp La1 is reduced. Therefore, in the lighting device of the present embodiment, when the time measurement result of the timer 26 reaches the determination time, the operation control circuit 25 stops the power supply operation of the lighting circuit 1 (the DC-DC conversion circuit 3 and the inverter circuit 4 are stopped). ) Is provided with a counter 27 that counts the number of stops. Then, when the count number of the counter 27 reaches the predetermined number, the operation control circuit 25 extends the determination time compared with the time measurement result of the timer 26, thereby reducing the number of times the discharge lamp La1 blinks at the time of abnormality. The detailed operation of the control unit 2 including the determination time extension process will be described below with reference to the flowchart shown in FIG. 2 and the waveform diagram of the input voltage Vin shown in FIG.

  First, the operation starts from “START” in step S1, and in the next “startup voltage determination” in step S2, the operation control circuit 25 determines whether the input voltage Vin is equal to or higher than the operation permission voltage V2 (within the start range). Confirm whether or not.

  If the input voltage Vin is within the startup range, the process proceeds to “no-load operation control” in step S3, and the discharge lamp La1 that is in the no-load state (undischarged state) is started. That is, a high voltage is applied to the discharge lamp La1 using the igniter circuit 5, and discharge of the discharge lamp La1 is started. At this time, in “first operation voltage determination” in step S4, the operation control circuit 25 monitors the input voltage Vin, and whether or not the input voltage Vin is equal to or higher than the operation maintaining voltage V1 (within the operation range). To check. If the input voltage Vin is within the operating range, the process proceeds to “lighting determination” in step S5, and the control unit 2 determines whether or not the discharge lamp La1 is lit. Here, when the discharge lamp La1 starts discharging, the output voltage Vo is lowered as compared with a non-load state (non-discharge state). Therefore, it is possible to determine that the discharge lamp La1 has been lit by detecting a decrease in the output voltage Vo in “lighting determination” in step S5. Further, since the output current Io increases when the discharge lamp La1 starts discharging, it can be determined that the discharge lamp La1 is lit by detecting an increase in the output current Io. As described above, the “first operation voltage determination” in step S4 and the “lighting determination” in step S5 are performed. If the input voltage Vin is within the operating range and the discharge lamp La1 is in the extinguished state, “nothing” in step S3 is performed. A loop that repeats “load operation control” is formed.

  And if it determines with discharge lamp La1 having turned on by "lighting determination" of step S5, it will transfer to "lighting control" of step S6, and the control part 2 will be the output electric power of the DC-DC conversion circuit 3. Feedback control is performed to obtain a desired value. Note that the “lighting control” in step S6 may be configured to perform feedback control so that the output voltage Vo or the output current Io of the DC-DC conversion circuit 3 becomes a desired value. At this time, in “second operation voltage determination” in step S7, the operation control circuit 25 monitors the input voltage Vin, and whether or not the input voltage Vin is equal to or higher than the operation maintaining voltage V1 (within the operation range). To check. If the input voltage Vin is within the operating range, the process proceeds to “load state determination” in step S8, and the control unit 2 determines the lighting state of the discharge lamp La1. As described above, the “second operating voltage determination” in step S7 and the “load state determination” in step S8 are performed. If the input voltage Vin is within the operating range and the discharge lamp La1 is in the normal lighting state, the process proceeds to step S6. A loop that repeats “lighting control” is formed.

  On the other hand, when a load abnormality (for example, a short circuit of the discharge lamp La1) is detected in the “load state determination” in step S8, the process proceeds to “protection stop” in step S9 and the power supply operation of the lighting circuit 1 is performed. The protection is stopped, and the process ends at "END" in step S10. In the protection stop state of the lighting circuit 1, the stop state of the power supply operation of the lighting circuit 1 is continued even when the input voltage Vin becomes equal to or higher than the operation permission voltage V2. Then, when the reset signal is input to the operation control circuit 25 from the inside or outside of the control unit 2, the protection stop state of the lighting circuit 1 is released.

  In addition, when the extinction (disappearance) of the discharge lamp La1 is detected in “load state determination” in step S8, the process returns to “startup voltage determination” in step S2.

  Here, it is assumed that an abnormality occurs in which the internal impedance of the DC power supply E1 or the line impedance increases. Then, due to this abnormality, the input voltage Vin is greatly reduced. In the “first operation voltage determination” in step S4 during the no-load operation control or the “second operation voltage determination” in step S7 during the lighting control, Assume that the input voltage Vin becomes less than the operation maintaining voltage V1. Then, the process proceeds to “determination process” in step S11 or step S12. Then, the timer 26 starts timing, and the operation control circuit 25 performs a comparison process that compares the timing result of the timer 26 with the determination time. Here, in the lighting device of this embodiment, the initial value T1 is set as the value of the determination time. Hereinafter, the determination time in which the initial value T1 is set is referred to as determination time T1. Then, when the time measurement result of the timer 26 becomes equal to or greater than the determination time T1, the operation control circuit 25 proceeds to step S13 “pause operation”, and the operation control circuit 25 stops the power supply operation of the lighting circuit 1. Then, the discharge lamp La1 is turned off. At this time, the counter 27 counts up the number of stops of the lighting circuit 1, and the count number becomes one. In the present embodiment, when the count number of the counter 27 reaches one (predetermined number), the operation control circuit 25 sets the determination time from the initial value T1 in “change determination time (T1 → T2)” in step S14. Is also set to a long value T2. Hereinafter, the determination time for which the value T2 is set is referred to as determination time T2. Thereafter, a start signal is output from the reset circuit (not shown) to the operation control circuit 25, and the process returns to “start-up voltage determination” in step S2. When the reset circuit is configured to output a start signal when the time measurement result of the timer 26 reaches a predetermined time, the value of the determination time is the power supply of the lighting circuit 1 earlier than the reset circuit outputs the start signal. It is necessary to set the operation to stop.

  Here, it is assumed that the discharge lamp La1 is extinguished at “operation pause” in step S13, whereby the input voltage Vin is restored (increased) and becomes equal to or higher than the operation permission voltage V2 again (see FIG. 3). In this case, it is assumed that the power supply operation of the lighting circuit 1 is resumed, and after the discharge lamp La1 is relighted, the input voltage Vin decreases again and becomes less than the operation maintaining voltage V1. At this time, the operation control circuit 25 performs a comparison process for comparing the time measurement result of the timer 26 with the determination time T2 set in step S14. Then, when the time count result of the timer 26 reaches the determination time T2, the operation control circuit 25 stops the power supply operation of the lighting circuit 1 again and turns off the discharge lamp La1 again. Since the determination time is already set to the value T2, the “determination time change (T1 → T2)” in step S14 is omitted, and the process returns to “startup voltage determination” in step S2.

  Further, in the “determination process” in step S11, when the input voltage Vin is recovered and becomes equal to or higher than the operation maintaining voltage V1 before the time measurement result of the timer 26 reaches the determination time, the process proceeds to “lighting determination” in step S5. . Further, in the “determination process” in step S12, when the input voltage Vin is recovered and becomes equal to or higher than the operation maintaining voltage V1 before the time measurement result of the timer 26 reaches the determination time, the process proceeds to “lighting determination” in step S8. .

  As described above, the lighting device of the present embodiment includes the lighting circuit 1, the input voltage detection unit 8, the timer 26, the operation control circuit 25, and the counter 27.

  The lighting circuit 1 performs a power supply operation for supplying power to the discharge lamp La1 (light source). The input voltage detector 8 detects the input voltage Vin of the lighting circuit 1. The timer 26 starts timing when the input voltage Vin becomes lower than the operation maintaining voltage V1 (first threshold voltage), and stops timing when the input voltage Vin becomes equal to or higher than the operation maintaining voltage V1. The operation control circuit 25 starts the power supply operation of the lighting circuit 1 when the input voltage Vin is equal to or higher than the operation permission voltage V2 (second threshold voltage) higher than the operation maintaining voltage V1. Further, when the input voltage Vin becomes less than the operation maintaining voltage V1, the operation control circuit 25 performs a determination process for comparing the time measurement result of the timer 26 with the determination time, and when the time measurement result of the timer 26 reaches the determination time, the lighting circuit 1 power supply operation is stopped. The operation control circuit 25 restarts the power supply operation of the lighting circuit 1 when the input voltage Vin becomes equal to or higher than the operation permission voltage V2. The counter 27 counts the number of times that the operation control circuit 25 has stopped the power supply operation of the lighting circuit 1 when the time measurement result of the timer 26 reaches the determination time.

  Then, when the count number of the counter 27 reaches one (predetermined number), the operation control circuit 25 extends the determination time from the determination time used in the previous determination process, that is, sets a value to be set for the determination time. The initial value T1 is changed to the value T2.

  As described above, when the count number of the counter 27 is 0, the initial value T1 is set as the value of the determination time, and when the count number of the counter 27 is 1 or more, the value of the determination time is the initial value T1. Longer T2 is set. That is, when the power supply operation of the lighting circuit 1 is stopped even once in “operation pause” in step S13, the determination time used for the subsequent determination processing is based on the determination time used for the first determination processing. Also gets longer. Therefore, since the possibility that the input voltage Vin returns to the operation maintaining voltage V1 or higher during the “determination process” in steps S11 and S12 is improved, the number of times the discharge lamp La1 blinks can be reduced, and the discharge lamp La1 The lifetime reduction can be suppressed. As examples of factors that cause the input voltage Vin to return to the operation maintaining voltage V1 or higher, the output of the DC power supply E1 is restored, the abnormality of the line impedance is recovered, or the input current Iin that flows much immediately after the start of lighting has passed the lighting time. It decreases with this.

  In the present embodiment, in “first operation voltage determination” in step S4 and “second operation voltage determination” in step S7, the values compared with the input voltage Vin are the same value (operation maintaining voltage V1). Although set, different values may be set.

  As a modification of the present embodiment, the determination time may be extended at the timing when the count number of the counter 27 reaches a plurality of times. In the above description, when the count number of the counter 27 reaches one time, the determination time is changed from the initial value T to the value T2, but the determination time is changed at the timing when the count number of the counter 27 reaches two or more times. It may be extended. The detailed operation of the control unit 2 in such a configuration will be described with reference to the flowchart shown in FIG. 4 and the waveform diagram of the input voltage Vin shown in FIG. In the flowchart shown in FIG. 4, the same control as in the flowchart shown in FIG. In the following example, the determination time is extended when the count number of the counter 27 reaches three.

When the operation control circuit 25 stops the power supply operation of the lighting circuit 1 in “operation pause” in step S13, the counter 27 counts up the number of stops in “stop count up” in step S131. Then, in “determination of stop count” in step S132, the operation control circuit 25 checks whether or not the count number of the counter 27 is three or more. When the count number of the counter 27 is less than 3, the process returns to “startup voltage determination” in step S2. On the other hand, when the count number of the counter 27 reaches 3 times in the “stop count up” in step S131, the process shifts to “change determination time (T1 → T2)” in step S14, and the operation control circuit 25 The determination time is set to a value T2 that is longer than the initial value T1. In addition, when the count number of the counter 27 is 4 times or more in the “stop count determination” in step S132,
Since the determination time has already been set to the value T2, “decision time change (T1 → T2)” in step S14 is omitted, and the process returns to “startup voltage determination” in step S2.

  That is, as shown in FIG. 5, the determination time set with the initial value T1 is used until the third determination process, and the determination time set with the value T2 is used after the fourth determination process. In this way, since the determination time extension process is performed at the timing when the count number of the counter 27 reaches a plurality of times, malfunction due to the influence of noise or the like can be prevented.

  Furthermore, as a modification of the present embodiment, the power supply operation of the lighting circuit 1 may be protected and stopped when the count number of the counter 27 reaches the upper limit number. In the above description, after the power supply operation of the lighting circuit 1 is stopped, as long as the input voltage Vin is recovered and becomes equal to or higher than the operation permission voltage V2, the discharge lamp La1 repeats blinking. Therefore, the operation control circuit 25 protects and stops the power supply operation of the lighting circuit 1 when the count number of the counter 27 reaches the preset upper limit number. The detailed operation of the control unit 2 in the case of such a configuration will be described with reference to the flowchart shown in FIG. In the flowchart shown in FIG. 6, the same control as in the flowchart shown in FIG.

  When the operation control circuit 25 stops the power supply operation of the lighting circuit 1 in “operation pause” in step S13, the counter 27 counts up the number of stops in “stop count up” in step S131. Then, in “stop count determination” in step S133, the operation control circuit 25 confirms whether or not the count number of the counter 27 is the upper limit count.

  When the count number of the counter 27 is less than the upper limit number and reaches the predetermined number, the determination time extension process is performed in “change determination time (T1 → T2)” in step S14, and “startup voltage determination” in step S2. Return to. When the count number of the counter 27 is less than the predetermined number, or less than the upper limit number and more than the predetermined number, the “determination time change (T1 → T2)” in step S14 is omitted, and “startup voltage determination” in step S2 is performed. Return.

  On the other hand, when the count number of the counter 27 reaches the upper limit number in the “stop count up” in step S131, the process shifts to “protection stop” in step S9, and the operation control circuit 25 stops the lighting circuit 1 in a protective manner. Then, the process ends at "END" in step S10.

  That is, when the count number of the counter 27 reaches the upper limit number, the operation control circuit 25 limits the number of times the discharge lamp La1 blinks when an abnormality occurs by stopping the lighting circuit 1 from being protected. In this way, the discharge lamp La1 is lit as much as possible by extending the determination time. However, when the lighting state of the discharge lamp La1 does not continue and flashes repeatedly, the life of the discharge lamp La1 is limited by limiting the number of flashes. The decrease can be suppressed.

  Here, when the discharge lamp La1 is repeatedly turned on and off by a user operation, the count number of the counter 27 may reach the upper limit number, and the lighting circuit 1 may be erroneously stopped. Therefore, the count number of the counter 27 may be reset when the steady state of the lighting circuit 1 continues for a predetermined time.

  As shown in FIG. 1, the control unit 2 includes a timer 28 that measures the time during which the discharge lamp La1 is continuously lit (lighting duration). The operation control circuit 25 determines that the lighting circuit 1 is in a steady state at least when the discharge lamp La1 is lit, and the counter 27 counts when the lighting duration time measured by the timer 28 reaches a predetermined time. Reset the number. A detailed operation of the control unit 2 in such a configuration will be described with reference to a flowchart shown in FIG. In the flowchart shown in FIG. 7, the same control as in the flowchart shown in FIGS.

  When the operation control circuit 25 determines that the discharge lamp La1 is in a normally lit state in “load state determination” in step S8, the operation control circuit 25 proceeds to “lighting duration determination” in step S15. The lighting duration measured by 28 is compared with a predetermined time. If the lighting duration is less than the predetermined time, the process returns to “lighting control” in step S6. On the other hand, if the lighting duration is equal to or longer than the predetermined time, the process proceeds to “stop count reset” in step S16, and the operation control circuit 25 resets the count number of the counter 27 and then returns to “lighting control” in step S6. .

  Further, when the operation control circuit 25 determines that the discharge lamp La1 is turned off (disappears) in the “load state determination” in step S8, the operation control circuit 25 proceeds to “lighting duration reset” in step S17, and the timer 28 measures. Reset the lighting duration. Thereafter, the process returns to “startup voltage determination” in step S2.

  Thus, when the steady state of the lighting circuit 1 continues for a predetermined time, the count number of the counter 27 is reset. Therefore, even when the discharge lamp La1 is repeatedly turned on and off by the user's operation, it is possible to prevent the lighting circuit 1 from being erroneously protected and stopped.

  Here, it is assumed that after the count number of the counter 27 reaches a predetermined number and the determination time is extended from the initial value T1 to the value T2, the steady state of the lighting circuit 1 continues for a predetermined time after recovering from the abnormal state. In this case, the count number of the counter 27 is reset by the above processing (steps S15 and S16), but the value of the determination time remains the value T2 extended from the initial value T1. Therefore, when an abnormality occurs again and the input voltage Vin becomes lower than the operation maintaining voltage V1, the determination time that is extended is used. Therefore, there is an advantage that the lighting of the discharge lamp La1 can be maintained as much as possible, and the number of blinks of the discharge lamp La1 can be reduced.

  However, since the power supply operation of the lighting circuit 1 is continued in a state where the input voltage Vin is low, the lighting circuit 1 may be deteriorated.

  Therefore, when the steady state of the lighting circuit 1 continues for a predetermined time or longer, that is, when the lighting continuous time measured by the timer 28 is longer than the predetermined time, the operation control circuit 25 resets the count number of the counter 27 and determines the determination time. Is returned to the initial value T1. Thereby, unnecessary continuation of the power supply operation of the lighting circuit 1 when the input voltage Vin is low can be prevented, and deterioration of the lighting circuit 1 can be suppressed.

  Further, as an example of the above modification, the operation control circuit 25 resets the count number of the counter 27 when the steady state of the lighting circuit 1 continues for a predetermined time or more, and determines the determination time as the steady state of the lighting circuit 1 elapses. You may comprise so that it may shorten in steps. As a method of shortening the determination time stepwise, there are a method of periodically subtracting a predetermined value from the current determination time value, a method of periodically dividing the predetermined value from the current determination time value, and the like.

  In this manner, by gradually reducing the determination time as the steady state of the lighting circuit 1 elapses, a relatively long determination time is used when a periodic decrease in the input voltage Vin occurs. The lighting of the discharge lamp La1 can be maintained as long as possible.

  As an example of the above modification, when the operation control circuit 25 shortens the determination time step by step as the steady state of the lighting circuit 1 elapses, the operation control circuit 25 reduces the determination time at a rate corresponding to the magnitude of the input voltage Vin. You may comprise. For example, the operation control circuit 25 periodically increases the value to be subtracted or divided from the current determination time value as the input voltage Vin increases.

  As described above, when the input voltage Vin is large, the determination time is quickly shortened to the initial value T1, and when the input voltage Vin is small, the determination time is slowly shortened to the initial value T1. Accordingly, even when the input voltage Vin is reduced in a short time, the discharge lamp La1 can be kept on.

  Further, as an example of the above modification, the operation control circuit 25 may be configured to determine that it is in a steady state when the discharge lamp La1 is lit and the input voltage Vin is equal to or higher than the operation maintaining voltage V1. In this case, the timer 28 is configured to measure a time during which the input lamp Vin is equal to or higher than the operation maintaining voltage V1 and the discharge lamp La1 is continuously lit. Then, the operation control circuit 25 determines whether or not the steady state of the lighting circuit 1 has continued for a predetermined time or more by comparing the time measurement result of the timer 28 with the predetermined time.

  Thus, it is added that the input voltage Vin is equal to or higher than the operation maintaining voltage V1 as a condition for determining that the lighting circuit 1 is in a steady state. Thereby, the count number of the counter 27 can be reset at a timing suitable for the magnitude of the input voltage Vin, and the determination time can be returned to the initial value T1.

  Moreover, you may comprise a lighting device so that control which combined each modification mentioned above may be performed.

(Embodiment 2)
The lighting device of the present embodiment is characterized in that each time the count number of the counter 27 increases, the determination time is made longer than the determination time used in the previous determination process. The circuit configuration of the lighting device of the present embodiment is the same as that of the lighting device of the first embodiment (see FIG. 1), and the same configuration and control as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted. To do.

  The detailed operation of the control unit 2 of the present embodiment will be described with reference to the flowchart shown in FIG. 8 and the waveform diagram of the input voltage Vin shown in FIG.

  As in the first embodiment, the input voltage Vin is maintained at the “first operation voltage determination” in step S4 during the no-load operation control or the “second operation voltage determination” in step S7 during the lighting control. When the voltage is less than V1 (out of the operating range), the timer 26 starts measuring time. Then, the operation control circuit 25 performs comparison processing for comparing the time measurement result of the timer 26 with the determination time T1. When the time measurement result of the timer 26 reaches the determination time T1 or longer, the operation control circuit 25 shifts to “operation pause” in step S13 and stops the power supply operation of the lighting circuit 1 to turn off the discharge lamp La1. . At this time, the counter 27 counts up the number of times the lighting circuit 1 is stopped.

  Next, in this embodiment, when the count number of the counter 27 reaches a predetermined number of times (in this embodiment, once), the process proceeds to “change determination time (add a constant value)” in step S14A. Then, the operation control circuit 25 sets a value T11 obtained by adding a constant value to the value (initial value T1) currently set for the determination time as the determination time. Thereafter, the process returns to “startup voltage determination” in step S2. In addition, after the discharge lamp La1 is turned on again, the input voltage Vin decreases again, and when the power supply operation of the lighting circuit 1 is stopped again at “operation pause” in step S13, the operation control circuit 25 sets the value. A value T12 obtained by adding a constant value to T11 is set as the determination time. That is, as shown in FIG. 9, every time the power supply operation of the lighting circuit 1 is stopped and the count number of the counter 27 increases, a fixed value is added to the value of the determination time, and the initial value T1 → value T11 → value T12. → The value T13 →... And the determination time is extended step by step. When the count number of the counter 27 is less than the predetermined number, the “determination time change (adding a constant value)” in step S14A is omitted, and the process returns to “starting voltage determination” in step S2.

  Here, when a significantly long value is set as the determination time, the operation of the lighting circuit 1 is continued with the input voltage Vin being low. The determination time in which the long value is set is repeated, which may lead to deterioration of the lighting circuit 1.

  However, in this embodiment, every time the count number of the counter 27 increases, the determination time is extended stepwise. Therefore, deterioration of the lighting circuit 1 can be suppressed by suppressing the time for executing the power supply operation of the lighting circuit 1 in a state where the input voltage Vin is low.

  In this embodiment, the determination time is extended stepwise by adding a constant value. However, the determination time may be extended stepwise by multiplying the constant value. .

  Further, as a modification of the present embodiment, the power supplied from the lighting circuit 1 to the discharge lamp La1 may be reduced when the determination time becomes longer than the threshold time. In the present modification, when the determination time is extended stepwise by the above control and the determination time is set longer than the threshold time, the operation control circuit 25 uses the power supplied from the lighting circuit 1 to the discharge lamp La1. For example, the power is reduced to such an extent that the discharge lamp La1 does not go out.

  As described above, when the determination time is longer than the threshold time, the input power (input current Iin) of the lighting device is reduced by reducing the power supplied to the discharge lamp La1. Therefore, the voltage drop due to the line impedance between the DC power supply E1 and the lighting device can be reduced. As a result, the input voltage Vin is less likely to fall below the operation maintaining voltage V1, and the lighting of the discharge lamp La1 can be maintained. If the lighting of the discharge lamp La1 cannot be maintained even if the power supplied to the discharge lamp La1 is reduced, the lighting circuit 1 is protected and stopped even if the input voltage Vin becomes equal to or higher than the operation permission voltage V2. It is desirable to continue the stop state of the power supply operation of the circuit 1.

  As a modification of the present embodiment, the lighting circuit 1 may be configured to stop protection when the determination time is longer than the threshold time. In this modification, when the determination time is extended stepwise by the above control and the determination time is set longer than the threshold time, the operation control circuit 25 stops the lighting circuit 1 from being protected, and the input voltage Vin is permitted to operate. Even if the voltage becomes equal to or higher than the voltage V2, the stopped state of the power supply operation of the lighting circuit 1 is continued.

  Thus, when the determination time becomes longer than the threshold time, the lighting circuit 1 is protected and stopped, thereby limiting the number of times the discharge lamp La1 blinks when an abnormality occurs. The discharge lamp La1 is turned on as much as possible by extending the determination time. However, when the lighting state of the discharge lamp La1 does not continue and flashes repeatedly, by limiting the number of flashes, the lifetime reduction of the discharge lamp La1 is suppressed. be able to.

  Further, by combining the above-described modifications, when the determination time becomes longer than the first threshold time, the power supplied to the discharge lamp La1 is reduced to a power that does not cause the discharge lamp La1 to disappear. When the determination time becomes longer than the second threshold time that is longer than the first threshold time, the lighting circuit 1 is protected and the power supply of the lighting circuit 1 is performed even when the input voltage Vin becomes equal to or higher than the operation permission voltage V2. You may comprise so that the stop state of operation may be continued.

  Moreover, you may comprise a lighting device so that the control combined with the control of Embodiment 1 may be performed.

(Embodiment 3)
The lighting device of the present embodiment sets a determination time for each lighting state of the discharge lamp La1, and sets the determination time corresponding to the lighting state of the discharge lamp La1 when the count number of the counter 27 reaches a predetermined number of times. It is characterized by extending more than. The circuit configuration of the lighting device of the present embodiment is the same as that of the lighting device of the first embodiment (see FIG. 1), and the same configuration and control as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted. To do.

  The detailed operation of the control unit 2 of the present embodiment will be described with reference to the flowchart shown in FIG.

  As in the first and second embodiments, when the input voltage Vin becomes less than the operation maintaining voltage V1 in the “first operating voltage determination” in step S4 and the “second operating voltage determination” in step S7, the timer 26 Starts timing.

  Here, in the present embodiment, the initial value T1a is set as the determination time used for the determination process in the “first operation voltage determination” in step S4 during the no-load operation control. Then, the operation control circuit 25 shifts to “operation pause” in step S13a when the time measurement result of the timer 26 is equal to or greater than the determination time T1a in “first operation voltage determination” in step S4. The discharge lamp La1 is extinguished by stopping the power supply operation. At this time, when the counter 27 counts up and the count number of the counter 27 reaches a predetermined number of times (for example, once), the operation control circuit 25 determines in step S14a "Change determination time (T1a → T2a)". The time is set to a value T2a longer than the initial value T1a.

  On the other hand, the initial value T1b is set for the determination time used for the determination process in the “second operating voltage determination” of step S7 during lighting control. Then, the operation control circuit 25 shifts to “operation pause” in step S13b when the time measurement result of the timer 26 becomes equal to or longer than the determination time T1b in “second operation voltage determination” in step S7, and the lighting circuit 1 The discharge lamp La1 is extinguished by stopping the power supply operation. At this time, when the counter 27 counts up and the count number of the counter 27 reaches a predetermined number of times (for example, once), the operation control circuit 25 determines in step S14b "Change determination time (T1b → T2b)". The time is set to a value T2b longer than the initial value T1b.

  Thus, in the present embodiment, different determination times are set when the discharge lamp La1 is started (no load) and when it is turned on. Then, when the count number of the counter 27 reaches a predetermined number, only the determination time corresponding to the lighting state of the discharge lamp La1 is extended. Due to the circuit operation of the lighting circuit 1, the required input power (input current Iin) may differ between the no-load state and the lighting state of the discharge lamp La1. In such a case, in the present embodiment, an appropriate determination time can be set according to the state of the discharge lamp La1. It is also effective when the allowable determination time differs due to circuit stress of the lighting circuit 1.

  Moreover, you may comprise a lighting device so that control combined with control of Embodiment 1, 2 may be performed.

  Moreover, in the said embodiment, although demonstrated as the lighting device which lights the discharge lamp La1, the kind of light source is not limited to the discharge lamp La1, For example, as shown in FIG. May be configured to light up. Since the light emitting diode La2 is direct current driven and does not require application of a high voltage at the time of starting, the lighting circuit 1 includes only the DC-DC conversion circuit 3.

DESCRIPTION OF SYMBOLS 1 Lighting circuit 2 Control part 21 Output control circuit 22 Drive circuit 24 Bridge drive circuit 25 Operation control circuit (control circuit)
26, 28 Timer 27 Counter 3 DC-DC conversion circuit 4 Inverter circuit 5 Igniter circuit 6 Voltage detection circuit 7 Current detection circuit 8 Input voltage detection unit La1 Discharge lamp (light source)
E1 DC power supply

Claims (14)

A lighting circuit for performing a power supply operation for supplying power to the light source;
An input voltage detector for detecting an input voltage of the lighting circuit;
A timer that starts timing when the input voltage is less than a first threshold voltage, and stops timing when the input voltage is greater than or equal to the first threshold voltage;
When the input voltage is equal to or higher than a second threshold voltage higher than the first threshold voltage, the power supply operation of the lighting circuit is started, and when the input voltage becomes less than the first threshold voltage, A determination process is performed for comparing the time measurement result of the timer with a determination time. When the time measurement result of the timer reaches the determination time, the power supply operation of the lighting circuit is stopped, and the input voltage is again set to the second voltage. A control circuit that restarts the power supply operation of the lighting circuit when the threshold voltage is exceeded;
A counter that counts the number of times the control circuit has stopped the power supply operation of the lighting circuit when the timed result of the timer reaches the determination time,
When the count number of the counter reaches a predetermined number, the control circuit extends the determination time from the determination time used in the previous determination process. The lighting device according to claim 1, wherein the control circuit extends the determination time from the determination time used in the previous determination process each time the count number of the counter increases. The lighting device according to claim 2, wherein the control circuit reduces the power supplied to the light source by the lighting circuit when the determination time is longer than a threshold time. When the determination time is longer than a threshold time, the control circuit continues the power supply operation stop state of the lighting circuit even when the input voltage becomes equal to or higher than the second threshold voltage. The lighting device according to claim 2 or 3. The control circuit sets the determination time for each lighting state of the light source, and sets the determination time corresponding to the lighting state of the light source when the count number of the counter reaches the predetermined number of times compared to the previous time. It extends, The lighting device of any one of Claims 1 thru | or 4 characterized by the above-mentioned. 2. The control circuit, when the count number of the counter reaches the predetermined number of times, the determination time is extended from the determination time used in the previous determination process. The lighting device according to any one of 5 to 5. When the count number of the counter reaches the upper limit number, the control circuit continues the power supply operation stop state of the lighting circuit even when the input voltage becomes equal to or higher than the second threshold voltage. The lighting device according to any one of claims 1 to 6. The control circuit determines that the control circuit is in a steady state at least when the light source is lit, and resets the count of the counter when the steady state continues for a predetermined time or longer. The lighting device of any one of thru | or 7. The control circuit determines that it is in a steady state at least when the light source is on, and resets the count number of the counter when the steady state continues for a predetermined time or more, and sets the determination time to an initial value. The lighting device according to any one of claims 1 to 7, wherein the lighting device is returned. The control circuit determines that it is in a steady state at least when the light source is lit, and resets the count number of the counter when the steady state continues for a predetermined time or more, and as the steady state elapses The lighting device according to any one of claims 1 to 7, wherein the determination time is reduced stepwise. The lighting device according to claim 10, wherein the control circuit shortens the determination time at a rate corresponding to the magnitude of the input voltage as the steady state elapses. The control circuit determines that the steady state is established when the light source is turned on and the input voltage is equal to or higher than the first threshold voltage. The lighting device according to item. The lighting device according to any one of claims 1 to 12, wherein the light source includes a discharge lamp. The lighting device according to any one of claims 1 to 12, wherein the light source includes a light emitting diode.

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