JP2015076288A - Lighting device and lighting fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device that reduces an overvoltage occurring due to an increase in ESR of an electrolytic capacitor under low-temperature environment, and to provide a lighting fixture.SOLUTION: A step-up chopper circuit 11 steps up an input voltage by switching a pulsating voltage inputted from a rectifier circuit 16 with a switching element. An electrolytic capacitor C1 is connected to an output side of the step-up chopper circuit 11 and rectifies an output voltage of the step-up chopper circuit 11. A light-source module 3 is connected in parallel to the electrolytic capacitor C1 and receives a driving current from the electrolytic capacitor C1. A control unit 14 adjusts an output of the step-up chopper circuit 11 by controlling on and off of a switching element included in the step-up chopper circuit 11. When a working temperature measured by a temperature measurement unit 12 is less than a reference temperature, the control unit 14 further lowers the output of the step-up chopper circuit than a normal time in which a measurement value of the temperature measurement unit 12 is more than or equal to the reference temperature.

Description

  The present invention relates to a lighting device and a lighting fixture, and more particularly, to a lighting device and a lighting fixture including a smoothing electrolytic capacitor.

  Conventionally, a lighting device using a light emitting diode as a light source has been proposed (see, for example, Patent Document 1). In the lighting device described in Patent Document 1, a DC voltage obtained by rectifying and smoothing a commercial AC power source with a step-up chopper circuit is accumulated in an electrolytic capacitor, converted into a necessary voltage with a step-down chopper circuit, and supplied to a light emitting diode. doing.

JP 2010-80906 A

  In the above-described lighting device, a smoothing capacitor is connected to the output stage of the step-down chopper circuit. A smoothing capacitor requires a part having a large capacitance, and an electrolytic capacitor may be used in some cases. When a lighting device is used in a cold environment such as outdoors, the electrolytic solution of the electrolytic capacitor freezes, increasing the equivalent series resistance (ESR) of the electrolytic capacitor and generating overvoltage. There was a possibility.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a lighting device and a lighting fixture that reduce an overvoltage generated by an increase in ESR of an electrolytic capacitor in a low temperature environment.

  The lighting device of the present invention includes a voltage conversion unit, an electrolytic capacitor, a temperature measurement unit, and a control unit. The voltage converter performs voltage conversion by switching an input voltage with a switching element. The electrolytic capacitor has a light source connected in parallel, smoothes the output voltage of the voltage conversion unit, and supplies a driving current to the light source. The temperature measuring unit measures an ambient temperature. The controller adjusts the output of the voltage converter by controlling on / off of the switching element. Furthermore, when the measured value of the temperature measuring unit is lower than the reference temperature, the control unit reduces the output of the voltage converting unit as compared with the normal time when the measured value of the temperature measuring unit is equal to or higher than the reference temperature.

  The lighting device of the present invention includes a voltage conversion unit, an electrolytic capacitor, a temperature measurement unit, a timer, and a control unit. The voltage converter performs voltage conversion by switching an input voltage with a switching element. The electrolytic capacitor has a light source connected in parallel, smoothes the output voltage of the voltage conversion unit, and supplies a driving current to the light source. The temperature measuring unit measures an ambient temperature. The timer measures an elapsed time after the voltage converter starts operating. The controller adjusts the output of the voltage converter by controlling on / off of the switching element. Furthermore, when the measured value of the temperature measuring unit is lower than the reference temperature, the control unit determines that the measured value of the temperature measuring unit is equal to or higher than the reference temperature until the elapsed time counted by the timer reaches a predetermined time. Compared with the normal time, the output of the voltage converter is reduced.

  In the lighting device, it is also preferable that the control unit is configured so that the reference temperature is 5 ° C.

  In this lighting device, it is also preferable that the control unit is configured to set the reference temperature to −10 ° C.

  In this lighting device, it is also preferable that the control unit is configured to set the reference temperature to −20 ° C.

  The lighting fixture of the present invention includes any one of the lighting devices described above and a light source that is turned on by the lighting device.

  In this lighting fixture, it is also preferable that the temperature measurement unit is configured to measure a temperature around the electrolytic capacitor inside the fixture main body that houses the lighting device and the light source.

  In this lighting fixture, it is also preferable that the temperature measuring unit is configured to measure a temperature outside a fixture main body that houses the lighting device and the light source.

  According to the lighting device of the present invention, when used at a temperature lower than the reference temperature, the output of the voltage conversion unit is lowered than normal, so even if the ESR of the electrolytic capacitor increases in a low temperature environment The voltage generated between both ends of the electrolytic capacitor can be reduced.

  According to the lighting fixture of the present invention, when used at a temperature lower than the reference temperature, since the output of the voltage conversion unit is lowered than usual, even if the ESR of the electrolytic capacitor increases in a low temperature environment The voltage generated between both ends of the electrolytic capacitor can be reduced.

It is a circuit diagram of the lighting fixture of this embodiment. It is a specific circuit diagram which shows the principal part of the lighting fixture of this embodiment. It is a figure which shows an example of the temperature characteristic of ESR of an electrolytic capacitor. It is a figure which shows the time change of the voltage which generate | occur | produces between the both ends of a smoothing capacitor when the lighting fixture of this embodiment is started at the normal time more than reference temperature. It is a figure which shows the time change of the voltage which generate | occur | produces between the both ends of a smoothing capacitor when the lighting fixture of this embodiment is started at the time of the low temperature below reference temperature. When the lighting fixture of this embodiment is started at a low temperature lower than the reference temperature, the operation when the control for suppressing the output voltage is not performed is shown. (A) shows the time change of the voltage generated between both ends of the smoothing capacitor. (B) is the figure which expanded and displayed the time-axis of the B section. It is a circuit diagram which shows the other circuit structure of the lighting fixture of this embodiment. It is a circuit diagram which shows another circuit structure of the lighting fixture of this embodiment. (A) is a side view of the lighting fixture of this embodiment, (b) is a bottom view of the lighting fixture of this embodiment.

  An embodiment in which the lighting device of the present invention is applied to a lighting fixture such as a street lamp will be described with reference to FIGS.

  FIG. 1 is a circuit diagram of a lighting fixture 1 according to the present embodiment. The lighting fixture 1 includes a lighting device 2 and a light source module 3.

  FIG. 9A is a side view showing a use state of the lighting fixture 1 according to the present embodiment, and FIG. 9B is a bottom view of the lighting fixture 1.

  The lighting fixture 1 of this embodiment is provided with the fixture main body 50 attached to the upper part of the pole 60 installed, for example in the street. The instrument main body 50 includes a flat box-shaped body 51 that is open on substantially the entire lower surface when attached to the pole 60, and a frame 52 that is attached to the body 51 so as to close the opening of the body 51. Is provided. A rectangular hole 53 is provided in the center of the frame body 52, and a light-transmitting panel 54 made of tempered glass is attached so as to close the hole 53. The lighting device 2 and the light source module 3 are housed inside the instrument body 50. The light source module 3 is disposed at a position facing the translucent panel 54, and light emitted from the light source module 3 is irradiated to the outside of the instrument body 50 (lower side in the attached state) through the translucent panel 54. .

  As shown in FIG. 1, the lighting device 2 of the present embodiment includes a step-up chopper circuit 11 (voltage conversion unit), an electrolytic capacitor C1, a temperature measurement unit 12, and a control unit 14, and is parallel to the electrolytic capacitor C1. The light source module 3 connected to is configured to light up. Moreover, the lighting device 2 of the present embodiment includes a timer 13 in addition to the above components. The lighting device 2 of the present embodiment further includes a filter circuit 15 and a rectifier circuit 16 in addition to the above-described components.

  The rectifier circuit 16 is a full-wave rectifier circuit in which four diodes are connected to form a bridge circuit. A commercial AC power supply 100 is connected to the input side of the rectifier circuit 16 via the filter circuit 15, and a boost chopper circuit 11 is connected to the output side of the rectifier circuit 16. An AC voltage is input to the rectifier circuit 16 from the commercial AC power supply 100 via the filter circuit 15, and the input AC voltage is full-wave rectified and output to the boost chopper circuit 11.

  The step-up chopper circuit 11 includes a switching element Q1, a choke coil L1, and a diode D1, as shown in the specific circuit diagram of FIG. One end of the choke coil L1 is connected to the output terminal on the high voltage side of the rectifier circuit 16. The other end of the choke coil L1 is connected to the drain electrode of the switching element Q1 made of an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). The source electrode of the switching element Q1 is connected to the output terminal on the low voltage side of the rectifier circuit 16 via the resistor R1 for current detection. The anode of the diode D1 is connected to the connection point of the choke coil L1 and the switching element Q1, and a smoothing electrolytic capacitor C1 is connected between the cathode of the diode D1 and the low-voltage side output terminal of the rectifier circuit 16. .

  A control signal is input from the control unit 14 to the gate electrode of the switching element Q1, and the on / off of the switching element Q1 is switched by this control signal.

  When the switching element Q1 is turned on, the current I1 flows through the path of the rectifier circuit 16, the choke coil L1, the switching element Q1, the resistor R1, and the rectifier circuit 16, and energy is accumulated in the choke coil L1. When the switching element Q1 is turned on, a current is supplied from the electrolytic capacitor C1 to the light source module 3. A voltage VR1 proportional to the current I1 flowing through the switching element Q1 is generated between both ends of the resistor R1, and this voltage VR1 is input to the control unit 14.

  On the other hand, when the switching element Q1 is turned off, a current flows through the path of the rectifier circuit 16 → the choke coil L1 → the diode D1 → the light source module 3 → the rectifier circuit 16, and the current is supplied to the light source module 3. When the switching element Q1 is turned off, the choke coil L1 releases the energy accumulated when the switching element Q1 is turned on, so that the electrolytic capacitor C1 reaches the voltage obtained by superimposing the voltage generated by the choke coil L1 on the input voltage V1 from the rectifier circuit 16. Charged.

  The electrolytic capacitor C1 is made of, for example, an aluminum electrolytic capacitor, and is connected to the output terminal of the boost chopper circuit 11 in order to smooth the output of the boost chopper circuit 11. Although the electrolytic capacitor C1 has a large capacity, since an electrolytic solution is used, the equivalent series resistance (ESR) tends to increase at low temperatures. FIG. 3 shows an example of the temperature characteristics of ESR. In the temperature characteristics shown in FIG. 3, if the operating temperature is 40 ° C. or higher, the ESR of the electrolytic capacitor C1 becomes almost zero, As the operating temperature decreases, the ESR of the electrolytic capacitor gradually increases. In the temperature characteristics of FIG. 3, when the operating temperature is lowered to 5 ° C., the ESR becomes about 10Ω, when the operating temperature is lowered to −10 ° C., the ESR becomes about 20Ω, and when the operating temperature is lowered to −20 ° C., the ESR is It is about 30Ω. The electrolytic capacitor C1 is not limited to an aluminum electrolytic capacitor, and may be a tantalum electrolytic capacitor.

  The light source module 3 includes a series circuit of a plurality of (for example, four in the circuit of FIG. 1) light emitting diodes 30 and is connected in parallel with the electrolytic capacitor C1. In the light source module 3, a plurality of light emitting diodes 30 are connected in series, but a plurality of light emitting diodes 30 may be connected in parallel. Further, the light emitting diode 30 may be one or plural. Moreover, although the lighting device 2 of this embodiment lights the light emitting diode 30 as a light source, the light source is not limited to the light emitting diode 30 and may be a solid light emitting element such as an electroluminescence device.

  The temperature measuring unit 12 is formed of, for example, a thermistor whose resistance value changes according to temperature, and the temperature sensing unit is exposed on the surface of the instrument body 50, for example, the lower surface of the frame body 52, as shown in FIG. 9B. And attached to the instrument body 50. The temperature measurement unit 12 is used to measure the temperature outside the instrument main body 50, and outputs a signal whose size changes according to the temperature outside the instrument main body 50 to the control unit 14. The temperature measuring unit 12 is housed inside the instrument main body 50, and is configured to output a signal whose size changes according to the temperature around the electrolytic capacitor C1 to the control unit 14 inside the instrument main body 50. It may be.

  The timer 13 measures the elapsed time after the boost chopper circuit 11 (voltage conversion unit) starts operating. The timer 13 of the present embodiment outputs a signal notifying that the predetermined time has elapsed to the control unit 14 when the result of measuring the elapsed time since the boost chopper circuit 11 starts operating reaches a predetermined time. .

  The control unit 14 includes a chopper control unit 17 that controls on / off of the switching element Q <b> 1 included in the boost chopper circuit 11, a determination unit 18, and a bias circuit 19.

  The chopper control unit 17 outputs a control signal to the gate electrode of the switching element Q1 at a predetermined switching cycle to turn on the switching element Q1. When the switching element Q1 is turned on and the current I1 flowing through the switching element Q1 increases, a voltage VR1 proportional to the current I1 is generated across the resistor R1. A voltage VR1 generated between both ends of the resistor R1 is fed back to the chopper controller 17. The chopper controller 17 compares the voltage VR1 with a predetermined reference voltage. When the voltage VR1 exceeds the reference voltage, the chopper controller 17 turns off the switching element Q1, and the on-duty of the switching element Q1 is adjusted. In this way, since the on-duty of the switching element Q1 is adjusted by the chopper controller 17, the output voltage of the boost chopper circuit 11 is controlled to be constant.

  The bias circuit 19 switches whether the bias voltage VB1 is superimposed on the voltage VR1 across the resistor R1 according to the determination result of the determination unit 18.

  When the determination unit 18 determines that control for suppressing the output voltage of the boost chopper circuit 11 is not performed, the bias circuit 19 does not superimpose the bias voltage VB1 on the both-ends voltage VR1 of the resistor R1, and the both-ends voltage VR1 is chopper-controlled as it is. Input to the unit 17. In this case, the chopper controller 17 performs a normal control operation, and controls the output voltage of the boost chopper circuit 11 to a preset target voltage.

  When the determination unit 18 determines that control to suppress the output voltage of the boost chopper circuit 11 is performed, the bias circuit 19 superimposes the bias voltage VB1 on the both-ends voltage VR1 of the resistor R1, and superimposes the bias voltage VB1 on the both-ends voltage VR1. The voltage thus inputted is input to the chopper controller 17. In this case, the chopper controller 17 compares the voltage (VR1 + VB1) in which the bias voltage VB1 is superimposed on the both-end voltage VR1 and a predetermined reference voltage, and when the voltage (VR1 + VB1) exceeds the reference voltage, the switching element Q1 Turn off. Therefore, by superimposing the bias voltage VB1, the ON time of the switching element Q1 is shortened, and the output voltage of the boost chopper circuit 11 is suppressed to a voltage lower than the target voltage.

  The determination unit 18 compares the temperature measured by the temperature measurement unit 12 (that is, the ambient temperature obtained from the output signal of the temperature measurement unit 12) with a preset reference temperature, and based on the result. It is determined whether or not control for suppressing the output voltage of the boost chopper circuit 11 is performed.

  During normal times when the measurement value of the temperature measurement unit 12 is equal to or higher than the reference temperature, the determination unit 18 determines not to perform control for suppressing the output voltage of the boost chopper circuit 11. In this case, the voltage VR1 across the resistor R1 is directly input to the chopper controller 17, and the chopper controller 17 performs a normal control operation to control the output voltage of the boost chopper circuit 11 to a preset target voltage.

  On the other hand, when the measured value of the temperature measurement unit 12 is a low temperature lower than the reference temperature, the determination unit 18 continues the boost chopper until a notification signal for notifying that a predetermined time has elapsed from the start of the boost operation is input from the timer 13. It is determined that control for suppressing the output voltage of the circuit 11 is performed. That is, the determination unit 18 controls the bias circuit 19 until the notification signal is input from the timer 13, and causes the chopper control unit 17 to input a voltage obtained by superimposing the bias voltage VB1 on the both-ends voltage VR1 of the resistor R1. In this case, the chopper control unit 17 compares the voltage (VR1 + VB1) obtained by superimposing the bias voltage VB1 on the voltage VR1 across the resistor R1 with a predetermined reference voltage. Therefore, the on-duty of the switching element Q1 is reduced by the amount that the bias voltage VB1 is superimposed, and the output voltage of the boost chopper circuit 11 is suppressed. Further, when the notification signal is input from the timer 13, the determination unit 18 controls the bias circuit 19 to stop the output of the bias voltage VB 1 and input the voltage VR 1 across the resistor R 1 to the chopper control unit 17 as it is. Then, the control for suppressing the output voltage is stopped.

  Below, the operation | movement at the time of power activation of the lighting fixture 1 is demonstrated based on FIGS. In the following description, the case where the reference temperature is set to 5 ° C. will be described as an example.

  First, the normal operation in which the ambient temperature becomes the reference temperature (5 ° C.) or higher will be described. FIG. 4 is a diagram illustrating a time change of the voltage V2 from when the lighting device 2 is turned on to when the boost chopper circuit 11 controls the voltage V2 across the electrolytic capacitor C1 to a predetermined target voltage in a normal state. It is.

  In the present embodiment, since the voltage conversion unit is constituted by the boost chopper circuit 11, when the lighting device 2 is turned on at time t10, the charging of the electrolytic capacitor C1 is started before the boost operation is started, The voltage V2 across the capacitor C1 gradually increases. At the time of start-up, the temperature of the electrolytic capacitor C1 is substantially the same as the ambient temperature, and the ESR slightly increases in the temperature range below 40 ° C. even if the operating temperature is 5 ° C. or more which is the reference temperature. Therefore, when the step-up operation starts at time t11, a state occurs in which the voltage V2 across the electrolytic capacitor C1 becomes higher than the target voltage at the steady state. Note that the determination unit 18 does not perform control to suppress the output voltage of the step-up chopper circuit 11 at normal times. If the ambient temperature is 5 ° C. or more of the reference temperature, the increase in ESR is suppressed to a value smaller than 10Ω, and even if the voltage V2 across the electrolytic capacitor C1 rises, the peak value V2p of the electrolytic capacitor C1 Since it is suppressed below the rated voltage during the transition, there is no practical problem. Further, when the boost chopper circuit 11 performs the boost operation, the components generate heat, and as a result, the temperature of the electrolytic capacitor C1 rises. Therefore, at time t12, the ESR decreases, and the voltage V2 across the electrolytic capacitor C1 is accordingly reduced. Is reduced to a target voltage.

  Next, the operation at a low temperature when the use temperature is lower than the reference temperature (5 ° C.) will be described. FIG. 5 is a diagram showing the change over time of the voltage V2 from when the lighting device 2 is turned on until the boost chopper circuit 11 controls the voltage V2 across the electrolytic capacitor C1 to a predetermined target voltage at low temperatures. It is.

  In a period t1 from when power is turned on to the lighting device 2 until the boost chopper circuit 11 starts the boost operation, a charging current flows through the electrolytic capacitor C1, and the voltage V2 across the electrolytic capacitor C1 gradually increases. Since the ESR of the electrolytic capacitor C1 is increased compared to the normal time at a low temperature, during the period t2 when the boost chopper circuit 11 starts the boost operation, the ESR increases, so that the ESR increases between both ends of the electrolytic capacitor C1. A voltage V21 higher than the target voltage V23 is generated. It should be noted that when the ambient temperature is lower than the reference temperature (5 ° C.), the determination unit 18 is a period until a notification signal is input from the timer 13 (that is, a period until a predetermined time elapses from the start of the boosting operation). t3) Control for suppressing the output voltage of the boost chopper circuit 11 is performed. That is, in the first period t2 of the period t3, the voltage V2 across the electrolytic capacitor C1 increases from the normal time due to the increase in ESR, but the output voltage of the boost chopper circuit 11 is suppressed. The both-end voltage V21 is suppressed to be lower than the rated voltage. In the latter half of the period t3 (after the period t2), the boost chopper circuit 11 performs a boost operation, and the components generate heat, thereby increasing the temperature of the electrolytic capacitor C1, so that the ESR is decreased and the electrolysis is performed accordingly. The voltage V2 across the capacitor C1 decreases. Note that, also in the second half of the period t3 (after the period t2), the control unit 14 reduces the output voltage of the boost chopper circuit 11 from the normal time, so that the voltage across the electrolytic capacitor C1 is greater than the target voltage V23. A lower voltage V22 is generated. When a predetermined time elapses from the start of the boost operation and the timer 13 outputs a notification signal to the control unit 14, the control unit 14 stops the control to suppress the output voltage of the boost chopper circuit 11, and the electrolytic capacitor C1 A predetermined target voltage V23 is generated between both ends (period t4 in FIG. 5).

  Incidentally, FIG. 6A shows that when the control of suppressing the output voltage of the boost chopper circuit 11 is not performed at a low temperature, the boost chopper circuit 11 sets the voltage V2 across the electrolytic capacitor C1 to a predetermined target after the power is turned on. The time change of the voltage V2 until it controls to a voltage is shown. FIG. 6B is an enlarged view of the time axis of part B in FIG. Since the ESR of the electrolytic capacitor C1 is higher than normal at low temperatures, when the boost chopper circuit 11 starts the boost operation, the voltage V2 across the electrolytic capacitor C1 rises at the switching timing of the switching element Q1. . Here, when the control for suppressing the output voltage of the boost chopper circuit 11 is not performed, the peak value V2p of the voltage V2 across the electrolytic capacitor C1 may increase to near the rated voltage at the time of transition, and the lighting device 2 There is a possibility that stress is applied to the circuit components constituting the circuit. On the other hand, in the present embodiment, the controller 14 controls the boost chopper circuit 11 until the predetermined time elapses from the start of the boost operation when the measured value of the temperature measurement unit 12 is lower than the reference temperature. An operation to suppress the output voltage is performed. Therefore, even if the ESR increases at low temperatures, the voltage V2 generated across the electrolytic capacitor C1 can be reduced, and the stress applied to the circuit components (including the electrolytic capacitor C1) constituting the lighting device 2 can be reduced.

  Here, the reference temperature is set to 5 ° C. at which the ESR of the electrolytic capacitor C1 rises to about 10Ω, for example. When the measurement value of the temperature measurement unit 12 is lower than 5 ° C., the control unit 14 reduces the output of the boost chopper circuit 11 compared to the normal time when the measurement value of the temperature measurement unit 12 is 5 ° C. or more. The voltage generated between both ends of the electrolytic capacitor C1 is suppressed.

  Note that the control unit 14 of the present embodiment compares the temperature measured by the temperature measurement unit 12 and the reference temperature when the voltage conversion unit starts operation. If the measured temperature at the time when the voltage conversion unit starts operation is less than the reference temperature, the control unit 14 increases the voltage of the boost chopper circuit until a predetermined time elapses after the voltage conversion unit starts operation. 11 is performed to suppress the output voltage. Here, the control unit 14 sequentially captures the temperature measurement value from the temperature measurement unit 12 at a predetermined time interval, compares the captured measurement temperature with the reference temperature, and when the measurement temperature is equal to or higher than the reference temperature, Control for suppressing the output voltage may be stopped.

  As described above, the lighting device 2 includes the voltage conversion unit (step-up chopper circuit 11), the electrolytic capacitor C1, the temperature measurement unit 12, the timer 13, and the control unit 14. The step-up chopper circuit 11 performs voltage conversion by switching the input voltage with the switching element Q1. The electrolytic capacitor C1 has a light source (light source module 3) connected in parallel, smoothes the output voltage of the voltage conversion unit, and supplies a drive current to the light source (light source module 3). The temperature measuring unit 12 is used for measuring the ambient temperature. The timer 13 measures the elapsed time after the voltage converter (boost chopper circuit 11) starts operating. The control unit 14 adjusts the output of the voltage conversion unit (boost chopper circuit 11) by controlling on / off of the switching element Q1. Further, when the measured value of the temperature measuring unit 12 is lower than the reference temperature, the control unit 14 determines that the measured value of the temperature measuring unit 12 is equal to or higher than the reference temperature until the elapsed time counted by the timer 13 reaches a predetermined time. Compared with the normal time, the output of the voltage converter is reduced.

  When the temperature is low, the ESR of the electrolytic capacitor C1 increases, which may increase the voltage generated across the electrolytic capacitor C1. When the measured value of the temperature measurement unit 12 is lower than the reference temperature, the control unit 14 suppresses the output voltage of the voltage conversion unit from the normal time until the elapsed time counted by the timer 13 reaches a predetermined time. ing. Therefore, even if the ESR increases at low temperatures, the voltage V2 generated across the electrolytic capacitor C1 is suppressed, and the stress applied to the circuit components (including the electrolytic capacitor C1) is reduced. Further, when a predetermined time has elapsed after the voltage converter (boost chopper circuit 11) starts operating, it is assumed that the temperature of the electrolytic capacitor C1 rises to some extent due to the heat generated by the components, and the ESR decreases as the temperature rises. Is done. Therefore, even if the control unit 14 stops the control for suppressing the output voltage of the voltage conversion unit after the lapse of the predetermined time, it is unlikely that an excessive voltage is generated between both ends of the electrolytic capacitor C1, and is added to the circuit component. Stress can be reduced, and the output voltage of the voltage converter can be controlled to a predetermined target voltage.

  Further, the lighting device 2 may include a voltage conversion unit (step-up chopper circuit 11), an electrolytic capacitor C1, a temperature measurement unit 12, and a control unit 14. The step-up chopper circuit 11 serving as a voltage converter performs voltage conversion by switching the input voltage with the switching element Q1. The electrolytic capacitor C1 has a light source (light source module 3) connected in parallel, smoothes the output voltage of the voltage conversion unit, and supplies a drive current to the light source (light source module 3). The temperature measuring unit 12 is used for measuring the ambient temperature. The control unit 14 adjusts the output of the step-up chopper circuit 11 by controlling on / off of the switching element Q1. Further, when the measured value of the temperature measuring unit 12 is lower than the reference temperature, the control unit 14 reduces the output voltage of the boost chopper circuit 11 compared to the normal time when the measured value of the temperature measuring unit 12 is equal to or higher than the reference temperature. Yes.

  When the temperature is low, the ESR of the electrolytic capacitor C1 increases, and the voltage V2 generated between both ends of the electrolytic capacitor C1 may increase. When the measurement value of the temperature measurement unit 12 is lower than the reference temperature, the control unit 14 lowers the output voltage of the voltage conversion unit (boost chopper circuit 11) than normal, so even if ESR increases at low temperatures, The voltage V2 generated between both ends of the electrolytic capacitor C1 is suppressed, and the stress applied to the circuit component is reduced.

  In the lighting device 2, the control unit 14 is configured to set the reference temperature to 5 ° C. Since the control unit 14 suppresses the output of the voltage conversion unit at a low temperature of less than 5 ° C., the voltage generated between both ends of the electrolytic capacitor C1 can be reduced even if the ESR increases at a low temperature.

  In the lighting device 2, it is also preferable that the control unit 14 is configured so that the reference temperature is −10 ° C. When the operating temperature is normally −10 ° C. or higher, control for suppressing the output voltage of the voltage conversion unit is not performed, and control for suppressing the output voltage of the voltage conversion unit is performed at a low operating temperature of less than −10 ° C. be able to.

  In the lighting device 2, it is also preferable that the control unit 14 is configured so that the reference temperature is −20 ° C. When the measurement temperature of the temperature measurement unit 12 is normally −20 ° C. or higher, the voltage conversion unit is not controlled to suppress the output voltage, and the voltage conversion is performed when the measurement temperature of the temperature measurement unit 12 is lower than −20 ° C. The control which suppresses the output voltage of a part can be performed.

  For example, when the lighting device 2 is used outdoors in a cold region, it is effective to set the reference temperature to −10 ° C. or −20 ° C. because the ambient temperature may be below freezing.

  Moreover, the lighting fixture 1 of this embodiment is equipped with the lighting device 2 mentioned above and the light source (light source module 3) lighted by the lighting device 2, and the lighting fixture 1 which reduced the stress added to a circuit component at low temperature is provided. realizable.

  Moreover, in the lighting fixture 1 of this embodiment, the temperature measurement part 12 is measuring the temperature of the outer side of the fixture main body 50 which accommodates the lighting device 2 and a light source (light source module 3).

  As a result, when the temperature outside the instrument body 50 is low, which is lower than the reference temperature, control is performed to suppress the output voltage of the voltage conversion unit. Therefore, even if ESR rises at low temperatures, between the both ends of the electrolytic capacitor C1. The generated voltage can be reduced.

  Moreover, in the lighting fixture 1 of this embodiment, the temperature measurement part 12 may measure the temperature around the electrolytic capacitor C1 inside the fixture main body 50 which accommodates the lighting device 2 and the light source (light source module 3).

  As a result, when the temperature around the electrolytic capacitor C1 is lower than the reference temperature inside the instrument body 50, control is performed to suppress the output voltage of the voltage conversion unit. The voltage generated between both ends of the capacitor C1 can be reduced. The temperature measuring unit 12 may measure the temperature around the electrolytic capacitor C1 inside the case (not shown) of the lighting device 2, or around the electrolytic capacitor C1 outside the case of the lighting device 2. The temperature may be measured.

  In the step-up chopper circuit 11 (voltage conversion unit) whose specific circuit diagram is shown in FIG. 2, the chopper control unit 17 monitors the current I1 flowing through the switching element Q1, but as shown in FIG. The output voltage V2 (that is, the voltage across the electrolytic capacitor C1) may be monitored.

  In the circuit shown in FIG. 7, a series circuit of resistors R2 and R3 is connected between the output terminals of the boost chopper circuit 11 (that is, between both ends of the electrolytic capacitor C1).

  The control unit 14 includes a chopper control unit 17 that controls on / off of the switching element Q1 included in the boost chopper circuit 11, a voltage detection unit 21, a determination unit 18, and a bias circuit 19.

  A voltage V3 obtained by dividing the output voltage V2 of the boost chopper circuit 11 by the resistance ratio of the resistors R2 and R3 is input to the voltage detection unit 21 and a signal having a magnitude proportional to the input voltage is output to the chopper control unit 17. To do.

  Based on the signal input from the voltage detection unit 21, the chopper control unit 17 controls the on-duty of the switching element Q1 so that the output voltage V2 of the boost chopper circuit 11 becomes a predetermined target voltage.

  The determination unit 18 compares the temperature measured by the temperature measurement unit 12 (that is, the ambient temperature obtained from the output signal of the temperature measurement unit 12) with a preset reference temperature, and based on the result. It is determined whether or not control for suppressing the output voltage of the boost chopper circuit 11 is performed.

  The bias circuit 19 switches whether to superimpose a constant bias voltage VB1 on the voltage V3 input to the voltage detection unit 21 according to the determination result of the determination unit 18.

  During normal times when the measurement value of the temperature measurement unit 12 is equal to or higher than the reference temperature, the determination unit 18 determines not to perform control for suppressing the output voltage of the boost chopper circuit 11. In this case, the bias circuit 19 does not superimpose the bias voltage VB1 on the voltage V3 at the connection point of the resistors R2 and R3, and the voltage detector 21 inputs a signal having a magnitude proportional to the voltage V3 to the chopper controller 17. The chopper controller 17 performs a normal control operation, and controls the output voltage V2 of the boost chopper circuit 11 to a preset target voltage.

  On the other hand, when the measured value of the temperature measurement unit 12 is a low temperature lower than the reference temperature, the determination unit 18 continues the boost chopper until a notification signal for notifying that a predetermined time has elapsed from the start of the boost operation is input from the timer 13. It is determined that control for suppressing the output voltage of the circuit 11 is performed. That is, the determination unit 18 controls the bias circuit 19 until the notification signal is input from the timer 13, and the voltage detection unit 21 applies a voltage obtained by superimposing the bias voltage VB1 on the voltage V3 at the connection point of the resistors R2 and R3. To input. The voltage detection unit 21 inputs a signal having a magnitude proportional to the voltage (V3 + VB1) to the chopper control unit 17, and the chopper control unit 17 switches the switching element based on the signal input from the voltage detection unit 21. Controls the on-duty of Q1. At this time, the chopper controller 17 limits the on-duty of the switching element Q1 to a small value by the amount that the bias voltage VB1 is superimposed, and the output voltage V2 of the boost chopper circuit 11 is set to a voltage lower than the target voltage. It is in a suppressed state. Further, when the notification signal is input from the timer 13, the determination unit 18 controls the bias circuit 19 to stop the output of the bias voltage VB 1 and stops the control to suppress the output voltage of the boost chopper circuit 11.

  As described above, also in the lighting device 2 whose circuit diagram is shown in FIG. 7, when the temperature measured by the temperature measurement unit 12 is a low temperature lower than the reference temperature, control for suppressing the output voltage of the voltage conversion unit is performed. . Therefore, even if the ESR rises at low temperatures, the voltage generated across the electrolytic capacitor C1 can be reduced.

  In the above-described embodiment, the voltage conversion unit is configured by the step-up chopper circuit 11, but the voltage conversion unit is not limited to the step-up chopper circuit 11, and may be a step-down chopper circuit, a step-up / step-down chopper circuit, a flyback converter, or the like. A switching circuit may be used.

  As shown in FIG. 8, the voltage conversion unit steps down the output voltage of the step-up chopper circuit 11 that boosts the pulsating voltage V <b> 1 that has been full-wave rectified by the rectifier circuit 16, and the light source module 3. The step-down chopper circuit 20 to be supplied may be constituted by a two-stage conversion unit.

  In the lighting device 2 shown in FIG. 8, a step-down chopper circuit 20 and a capacitor C2 are added to the lighting device 2 shown in FIG. In addition, since components other than the step-down chopper circuit 20 and the capacitor C2 are the same as those of the lighting device 2 shown in FIG. 1, common components are denoted by the same reference numerals, and description thereof is omitted.

  The step-down chopper circuit 20 is provided on the output side of the step-up chopper circuit 11. The step-down chopper circuit 20 steps down the output voltage of the step-up chopper circuit 11 by switching the DC voltage (the voltage V2 across the electrolytic capacitor C1) boosted by the step-up chopper circuit 11 with a switching element, and the DC voltage has a predetermined voltage value. Generate voltage.

  The capacitor C2 is made of, for example, an aluminum electrolytic capacitor and is connected between the output terminals of the step-down chopper circuit 20 to smooth the output voltage of the step-down chopper circuit 20. In the circuit shown in FIG. 8, the light source module 3 is connected in parallel with the capacitor C2, and a drive current is supplied from the capacitor C2 to the light source module 3, so that the light source module 3 is turned on.

  The control unit 14 includes a first control unit 141 that controls the output of the step-up chopper circuit 11 and a second control unit 142 that controls the output of the step-down chopper circuit 20.

  The first control unit 141 compares the measured value of the temperature measurement unit 12 with a predetermined reference temperature, and switches whether to perform control for suppressing the output voltage of the boost chopper circuit 11 according to the comparison result. . The operation of the first controller 141 is the same as that of the controller 14 of the lighting device 2 whose circuit diagram is shown in FIG.

  Whether the second control unit 142 compares the temperature obtained from the output signal of the temperature measurement unit 12 with a predetermined reference temperature, and performs control to suppress the output voltage of the step-down chopper circuit 20 according to the comparison result. Switch between no. If the temperature measured by the temperature measurement unit 12 is equal to or higher than the reference temperature, the second control unit 142 does not perform control to suppress the output voltage of the step-down chopper circuit 20, and the step-down chopper circuit 20 performs a predetermined voltage across the capacitor C2. Generate a DC voltage of the value. On the other hand, if the temperature measured by the temperature measurement unit 12 is lower than the reference temperature, the second control unit 142 performs control to suppress the output voltage of the step-down chopper circuit 20, and even if the ESR rises at a low temperature, the capacitor The voltage generated between both ends of C2 can be reduced.

  The capacitor C2 is not limited to an aluminum electrolytic capacitor, and may be a film capacitor. When the capacitor C2 is a film capacitor, the ESR does not increase so much even at a low temperature. Therefore, the second control unit 142 does not need to perform control for suppressing the output voltage of the step-down chopper circuit 20 even at a low temperature.

  The present embodiment is an embodiment in which the lighting device 2 of the present invention is applied to a street light that is attached to an upper portion of a pole 60 installed on a street and illuminates the street. However, the lighting device is not limited to a street light. The lighting device 2 of the present invention may be applied to lighting fixtures used for other purposes.

  It should be noted that a wide variety of different embodiments can be configured without departing from the spirit and scope of the present invention, and the present invention is not limited to a specific embodiment.

DESCRIPTION OF SYMBOLS 1 Lighting fixture 2 Lighting device 3 Light source module (light source)
11 Boost chopper circuit (voltage converter)
12 Temperature Measurement Unit 13 Timer 14 Control Unit 16 Rectifier Circuit 30 Light-Emitting Diode (Light Source)
50 Instrument body C1 Electrolytic capacitor Q1 Switching element

Claims (8)

A voltage converter that performs voltage conversion by switching the input voltage with a switching element; and
An electrolytic capacitor connected to the light source in parallel, smoothing the output voltage of the voltage converter, and supplying a driving current to the light source;
A temperature measuring unit for measuring the ambient temperature;
When the output of the voltage converter is adjusted by controlling on / off of the switching element, and the measured value of the temperature measuring unit is lower than a reference temperature, the measured value of the temperature measuring unit is equal to or higher than the reference temperature. And a control unit that reduces the output of the voltage conversion unit as compared to the normal time. A voltage converter that performs voltage conversion by switching the input voltage with a switching element; and
An electrolytic capacitor connected to the light source in parallel, smoothing the output voltage of the voltage converter, and supplying a driving current to the light source;
A temperature measuring unit for measuring the ambient temperature;
A timer for measuring the elapsed time since the voltage converter started operation;
When the output of the voltage converter is adjusted by controlling on / off of the switching element, and the measured value of the temperature measuring unit is lower than a reference temperature, the elapsed time counted by the timer reaches a predetermined time. And a controller that lowers the output of the voltage converter compared to a normal time when the measured value of the temperature measuring unit is equal to or higher than the reference temperature.   The lighting device according to claim 1, wherein the control unit is configured to set the reference temperature to 5 ° C.   The lighting device according to claim 1, wherein the control unit is configured to set the reference temperature to −10 ° C.   The lighting device according to claim 1, wherein the control unit is configured to set the reference temperature to −20 ° C. 3.   An illumination fixture comprising: the lighting device according to any one of claims 1 to 5; and a light source that is turned on by the lighting device.   The lighting apparatus according to claim 6, wherein the temperature measuring unit is configured to measure a temperature around the electrolytic capacitor in an apparatus main body that houses the lighting device and the light source.   The lighting fixture according to claim 6, wherein the temperature measuring unit is configured to measure a temperature outside a fixture main body that houses the lighting device and the light source.

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