JP2017084723A - Lighting device and illuminating fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device and an illuminating fixture capable of stabilizing a turning-off operation of a light source on receipt of a turning-off instruction from a dimmer.SOLUTION: A lighting device comprises: a step-up chopper circuit that steps up a DC voltage obtained by rectifying an AC voltage from an AC power supply; a buck converter circuit that steps down the DC voltage stepped-up by the step-up chopper circuit, and turns on a light source by the stepped-down DC voltage; and a control device that stops the step-up chopper circuit and the buck converter circuit in a preliminarily set order on receipt of a turning-off instruction from a dimmer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting device and a lighting fixture.

  Patent Document 1 discloses a lighting device. In the lighting device, the boost chopper circuit boosts a DC voltage obtained by rectifying the AC voltage from the AC power supply. The buck converter circuit steps down the DC voltage boosted by the step-up chopper circuit, and turns on the light source by the stepped-down DC voltage. The control device is driven by power supply from the control power supply circuit. The control device controls the operation of the boost chopper circuit and the operation of the buck converter circuit.

Japanese Unexamined Patent Publication No. 2015-159036

  In the lighting device described in Patent Document 1, the order in which the boost chopper circuit and the buck converter circuit are stopped when a turn-off instruction is received from the dimmer is not clarified. For this reason, the light-off operation of the light source is not stable.

  The present invention has been made to solve the above-described problems. An object of the present invention is to provide a lighting device and a lighting fixture that can stabilize the light-off operation of a light source when receiving a light-off instruction from a dimmer.

  A lighting device according to the present invention includes a step-up chopper circuit that boosts a DC voltage obtained by rectifying an AC voltage from an AC power source, and a step-down DC voltage that is boosted by the step-up chopper circuit. And a control device for stopping the step-up chopper circuit and the buck converter circuit in a preset order when receiving a turn-off instruction from the dimmer.

  The lighting fixture which concerns on this invention was equipped with the said lighting device.

  According to these inventions, when a turn-off instruction is received from the dimmer, the boost chopper circuit and the buck converter circuit are stopped in a preset order. For this reason, the light-off operation of the light source can be stabilized.

It is a circuit diagram of the lighting fixture provided with the lighting device in Embodiment 1 of this invention. It is a timing chart for demonstrating the light extinction operation | movement of LED when the lighting device in Embodiment 1 of this invention receives a light extinction instruction | indication from a light control device. It is a flowchart for demonstrating operation | movement of the control apparatus at the time of receiving the light extinction instruction | indication from a light controller in the lighting device in Embodiment 1 of this invention. It is a circuit diagram for demonstrating the modification of the control apparatus of the lighting fixture provided with the lighting device in Embodiment 1 of this invention. It is a circuit diagram for demonstrating the periphery of the modification of the control apparatus of the lighting fixture provided with the lighting device in Embodiment 1 of this invention. It is a timing chart for demonstrating the light extinction operation | movement of LED when the lighting device in Embodiment 2 of this invention receives a light extinction instruction | indication from a light control device. It is a flowchart for demonstrating operation | movement of the control apparatus at the time of receiving the light extinction instruction | indication from a light controller in the lighting device in Embodiment 2 of this invention. It is a timing chart for demonstrating the light extinction operation | movement of LED when the lighting device in Embodiment 3 of this invention receives a light extinction instruction | indication from a light control device. It is a flowchart for demonstrating operation | movement of the control apparatus at the time of receiving the light extinction instruction | indication from a light controller in the lighting device in Embodiment 3 of this invention.

  A mode for carrying out the invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the part which is the same or it corresponds in each figure. The overlapping description of the part is appropriately simplified or omitted. The relationship between the sizes of the components may be different from the actual one.

Embodiment 1 FIG.
1 is a circuit diagram of a lighting fixture including a lighting device according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the luminaire 1 is connected to an AC power source 2. The luminaire 1 includes a light source module 3 and a lighting device 4.

  For example, the light source module 3 is a module in which a plurality of LEDs 5 are connected in series in a row. Each of the LEDs 5 is an LED element formed of an inorganic semiconductor. For example, each of the LEDs 5 may be an organic EL element formed of an organic semiconductor.

  The lighting device 4 includes a rectifier circuit 6, a capacitor 7, a resistor 8, a resistor 9, a step-up chopper circuit 10, a buck converter circuit 11, a lamp connection detection circuit 12, a control power supply circuit 13, a drive circuit 14, and a control device 15.

  The rectifier circuit 6 is connected to the AC power source 2. The low potential side of the rectifier circuit 6 is grounded. The capacitor 7 is connected in parallel to the output terminal of the rectifier circuit 6. The resistors 8 and 9 are connected in series to form a voltage dividing circuit. The voltage dividing circuit is connected to the capacitor 7 in parallel.

Boost chopper circuit 10 includes an inductor 16 and the first switching element _{Q 1,} a diode 17 and a capacitor 18 and resistor 19 and the resistor 20.

  One end of the inductor 16 is connected to the high potential side of the rectifier circuit 6.

In this embodiment, the first switching element _Q 1 is a MOSFET. The first switching element Q ₁ is provided with a (gate in this embodiment) control terminal (source in the present embodiment) and the second terminal (the drain in the present embodiment) first terminal.

The first terminal of the first switching element Q ₁ is connected to the other end of the inductor 16. First second terminal of the switching element Q ₁ is are connected to the low potential side of the rectifier circuit 6.

The anode of the diode 17 is connected to a connection point between the other end and the first first terminal of the switching element to Q ₁ inductor 16. The capacitor 18 is an electrolytic capacitor. The positive electrode of the capacitor 18 is connected to the cathode of the diode 17. The negative electrode of the capacitor 18 is connected to the low potential side of the rectifier circuit 6.

  The resistor 19 and the resistor 20 are connected in series to form a voltage dividing circuit. The voltage dividing circuit is connected to the capacitor 18 in parallel.

Buck converter circuit 11 includes a second switching element _{Q 2} and the diode 21 and the inductor 22 and a capacitor 23 and a detection resistor 24.

And the second switching element Q ₂ and the diode 21 form a series circuit. The series circuit is connected in parallel with the capacitor 18 of the boost chopper circuit 10.

In this embodiment, the second switching element _Q 2 is a MOSFET. The second switching element Q ₂ is provided with a (gate in this embodiment) control terminal (source in the present embodiment) and the second terminal (the drain in the present embodiment) first terminal.

The first terminal of the second switching element Q ₂ are connected to the positive electrode of the capacitor 18. The second terminal of the second switching element Q ₂ are connected to the cathode of the diode 21. The anode of the diode 21 is connected to the negative electrode of the capacitor 18.

  The inductor 22, the capacitor 23, and the detection resistor 24 are connected in series in this order to form a series circuit. The series circuit is connected to the diode 21 in parallel.

  The lamp connection detection circuit 12 is connected to the capacitor 23 in parallel. The lamp connection detection circuit 12 includes a resistor 25 and a resistor 26.

  The resistor 25 and the resistor 26 are connected in series to form a voltage dividing circuit. The voltage dividing circuit is connected to the light source module 3 in parallel.

  In the present embodiment, the power input terminal of the control power circuit 13 is connected to the output terminal of the boost chopper circuit 10. Specifically, the control power supply circuit 13 is connected to the subsequent stage of the capacitor 18.

The power input terminal of the drive circuit 14 is connected to the first power output terminal of the control power circuit 13. The first signal output terminal of the drive circuit 14 is connected to the first control terminal of the switching element Q _1. The second signal output terminal of the drive circuit 14 is connected to the second control terminal of the switching element Q _2.

  The digital interface circuit 27 is provided so as to accept an input of a dimming signal from the dimmer 28.

A power input terminal of the control device 15 is connected to a second power output terminal of the control power circuit 13. A first signal input terminal of the control device 15 is connected to a connection point between the resistor 8 and the resistor 9. The second signal input terminal of the control device 15 is connected to a connection point between the resistor 19 and the resistor 20. Third signal input of the control device 15 is connected to the first second terminal of the switching element Q _1. The fourth signal input terminal of the control device 15 is connected to a connection point between the resistor 25 and the resistor 26. The fifth signal input terminal of the control device 15 is connected to a connection point between the capacitor 23 and the detection resistor 24.

For example, when the AC power supply 2 is turned on by operating the wall switch SW, the rectifier circuit 6 rectifies the AC voltage from the AC power supply 2. The control power supply circuit 13 is activated by the DC voltage rectified by the rectifier circuit 6. The control power supply circuit 13 supplies a power supply voltage V _ACC to the drive circuit 14. The control power supply circuit 13 supplies the power supply voltage V _DCC to the control device 15.

Boost chopper circuit 10 boosts the DC voltage rectified by the rectifier circuit 6 by operating the first switching element Q _1. As a result, the step-up chopper circuit 10 outputs a first output voltage _{V 1.} The first output voltage V ₁ is used as a power supply voltage for the control power supply circuit 13.

Buck converter circuit 11 steps down the first output voltages V ₁ by operating the second switching element Q _2. As a result, the buck converter circuit 11 outputs the second output voltage _{V 2.} The second output voltage V ₂ is used for lighting the light source module 3.

The resistors 8 and 9 divide the voltage across the capacitor 7. As a result, the input voltage _{V in} is generated. Resistor 19 and resistor 20 divide the voltage across capacitor 18. As a result, the detection voltage _Vp is generated. The resistors 25 and 26 divide the voltage across the capacitor 23. As a result, the detection voltage _Vb is generated.

Control device 15, receives the input of the input voltage _{V in.} Controller 15 receives an input of the detection voltage _{V p.} The control device 15 receives an input of the detection voltage _Vb .

The control device 15 detects the current _Ip flowing through the boost chopper circuit 10. Controller 15 detects the current _{I b} flowing through the buck converter circuit 11 based on the detection voltage _{V ILED.} The control device 15 detects the LED current I _LED that flows through the light source module 3 based on the detection voltage V _ILED .

Controller 15 starts the outputs the PWM signal _{S b} of the PWM signal _{S p} in any different timings by the user's setting.

For example, the control unit 15, so that the output voltage of the step-up chopper circuit 10 is a constant value based on the detected voltage V _p, to adjust the PWM signal S _p. Specifically, the control unit 15, so that the output voltage of the step-up chopper circuit 10 coincides with a preset boost target value, adjusting the PWM signal S _p. In particular, the control device 15, in order to perform a power factor improvement control, controls the first switching of the switching element Q ₁ in the so-called critical conduction mode or continuous current mode and the like.

The PWM signal _Sp is input to the drive circuit 14. Drive circuit 14 generates a drive signal by amplifying the PWM signal S _p to the voltage required to turn on the first switching element Q1. Drive circuit 14 outputs the drive signal to the first control terminal of the switching element Q _1.

The first switching element _{Q 1} is, carrying out the on-off operation according to the PWM signal _{S p.} As a result, the boost chopper circuit 10 performs a desired boost operation and power factor correction operation.

For example, the control unit 15, so that LED current _{I LED} is a constant value based on the detection voltage _{V ILED,} adjusts the PWM signal _{S b.} Specifically, the control unit 15, so that the output voltage of the buck converter circuit 11 coincides with a preset step-down target value, adjusting the PWM signal S _b.

The PWM signal _Sb is input to the drive circuit 14. Drive circuit 14 amplifies the PWM signal S _b to a voltage necessary for turning on the second switching element Q ₂ generates a driving signal. Drive circuit 14 outputs the drive signal to the second control terminal of the switching element Q _2.

The second switching element _{Q 2} is, to implement the on-off operation according to the PWM signal _{S b.} As a result, the buck converter circuit 11 turns on the plurality of LEDs 5 of the light source module 3 with desired brightness.

  In FIG. 1, the control device 15 is provided in the form of an integrated circuit package (IC package) in which a circuit board on which a CPU or the like is formed is sealed with a resin package or the like. There are several variations of the integrated circuit package. For example, the control device 15 includes an A / D conversion circuit 29 and a microcomputer 30.

A / D conversion circuit 29 converts the input voltage _{V in} and the detection voltage _{V p} and detection voltage _{V b} detected voltage _{V ILED} and the current _{I p} to each digital value.

  The microcomputer 30 includes a memory, an arithmetic processing unit, and the like. For example, the memory is a flash memory. The memory stores various digital information necessary for lighting control and a control program. The arithmetic processing unit executes a control program for lighting control using various information converted into a digital value via the A / D conversion circuit 29 and various digital information stored in the memory.

The microcomputer 30 executes a control program to calculate the operation target value of the on-duty, etc. for each of the switching control of the first switching element Q ₁ and the second switching element Q _2. For example, the microcomputer 30 to perform the desired power factor improvement control with the boosting chopper circuit 10 to obtain a desired boosted voltage, and calculates the first operation target value of the switching element Q _1. For example, the microcomputer 30, so that a desired brightness in the plurality of LED5 of the light source module 3 is obtained, to calculate the second operation target value of the switching element Q _2.

  When the dimmer 28 is operated, the digital interface circuit 27 receives an input of a dimming signal from the dimmer 28. The dimming signal is transmitted from the digital interface circuit 27 to the microcomputer 30.

Microcomputer 30, so as to light the plurality of LED5 of the light source module 3 in dimming rate in accordance with the dimming signal, and calculates the operation target value of the duty cycle such as the second switching element Q _2. The microcomputer 30 outputs the calculated operation target value at the given pulse width, period, satisfy the duty or the like as a PWM signal S _p and the PWM signal S _b, respectively.

  In the present embodiment, when an operation corresponding to the turn-off instruction is performed in the dimmer 28, the digital interface circuit 27 receives an input of a signal corresponding to the turn-off instruction from the dimmer 28. The signal is transmitted from the digital interface circuit 27 to the microcomputer 30.

  The control device 15 stops the boost chopper circuit 10 and the buck converter circuit 11 in a preset order based on the signal. Specifically, the control device 15 starts the stop operation of the buck converter circuit 11 after the boost chopper circuit 10 starts the stop operation.

Next, the turning-off operation of the LED 5 when receiving a turning-off instruction from the dimmer 28 will be described with reference to FIG.
FIG. 2 is a timing chart for explaining the operation of turning off the LED when the lighting device according to Embodiment 1 of the present invention receives a turn-off instruction from the dimmer.

Top of FIG. 2 is a timing chart showing a first variation of the output voltage V ₁ of the step-up chopper circuit 10. Second row from the top in FIG. 2 is a timing chart showing a first state of the switching element Q _1. The third stage from the top in FIG. 2 is a timing chart showing the second output voltage V ₂ of the buck converter circuit 11. Fourth stage from the top in FIG. 2 is a timing chart showing a second state of the switching element Q _2. The fifth row from the top in FIG. 2 is a timing chart showing changes in the LED current I _LED flowing through the light source module 3.

At time T1, the control device 15 receives a turn-off instruction from the dimmer 28. At this time, the control unit 15 starts the switching of the stop operation of the second switching element Q _2. From time T1 until just before time T2, the control unit 15 gradually stops the second switching of the switching element Q ₂ as feedback to the step-up chopper circuit 10 is in time. Specifically, the control unit 15 gradually reduces the duty ratio in the second switching of the switching element Q _2. At time T2, the control unit 15 completely stops the second switching element _{Q 2.}

As a result, during the period from time T1 to just before time T2, the second output voltage V ₂ of the buck converter circuit 11 gradually decreases. At time T2, the second output voltage _{V 2} 0 of the buck converter circuit 11.

For this reason, the LED current I _LED flowing through the light source module 3 gradually decreases from time T1 to immediately before time T2. At time T2, the LED current I _LED flowing through the light source module 3 becomes zero. In this case, the LED 5 is completely turned off at time T2 while fading out.

After a preset time from the time T1, the controller 15 starts the first stop operation switching element Q _1. For example, at time T3 the second switching element Q ₂ is completely stopped, the control unit 15 completely stops the first switching element Q _1. It is also possible to initiate the first stop operation switching element Q ₁ before the second switching element Q ₂ is completely stopped.

As the first stop switching element _{Q 1,} the first output voltage _{V 1} of the step-up chopper circuit 10 is reduced.

Next, the operation of the control device 15 when receiving a turn-off instruction from the dimmer 28 will be described with reference to FIG.
FIG. 3 is a flowchart for explaining the operation of the control device when receiving a turn-off instruction from the dimmer in the lighting device according to Embodiment 1 of the present invention.

  In step S <b> 1, the control device 15 determines whether a turn-off instruction has been received from the dimmer 28. If the control device 15 has not received a turn-off instruction from the dimmer 28 in step S1, step S1 is repeated. If the control device 15 receives a turn-off instruction from the dimmer 28 in step S1, the process proceeds to step S2.

  In step S2, the control device 15 causes the buck converter circuit 11 to start a stop operation. Thereafter, the process proceeds to step S3. In step S3, the control device 15 causes the boost chopper circuit 10 to start a stop operation. Thereafter, the operation ends.

  According to the first embodiment described above, the boost chopper circuit 10 and the buck converter circuit 11 are stopped in a preset order when a turn-off instruction is received from the dimmer 28. For this reason, the light-off operation of the LED 5 can be stabilized.

Specifically, after the buck converter circuit 11 starts the stop operation, the boost chopper circuit 10 starts the stop operation. At this time, the second switching of the switching element Q ₂ is gradually stopped. Therefore, the output voltage V ₁ of the step-up chopper circuit 10 too late feedback of the step-up chopper circuit 10 can be prevented from overshooting.

  The control device 15 may include a plurality of microcomputers 30. The plurality of microcomputers 30 may include a “first microcomputer 30” that controls the boost chopper circuit 10 and a “second microcomputer 30” that controls the buck converter circuit 11. When a plurality of microcomputers 30 are provided, a program inside each microcomputer 30 may be constructed so that different switching control start timings and the like can be set for each microcomputer 30. Alternatively, a plurality of microcomputers 30 may operate in cooperation. For example, a plurality of microcomputers 30 may communicate with each other, and a signal indicating the driving state of the boost chopper circuit 10 and a signal indicating the driving state of the buck converter circuit 11 may be exchanged between the plurality of microcomputers 30.

Next, a modified example of the control device 15 will be described with reference to FIGS. 4 and 5.
FIG. 4 is a circuit diagram for explaining a modification of the control device for the lighting fixture provided with the lighting device according to Embodiment 1 of the present invention. FIG. 5 is a circuit diagram for explaining the periphery of a modification of the control device for the lighting fixture provided with the lighting device according to Embodiment 1 of the present invention.

  In FIG. 4, the control device 15 accommodates an “analog circuit” such as the control power supply circuit 13 and the drive circuit 14 and a “digital circuit” such as the microcomputer 30 in a single IC package. Each circuit is interconnected with each other inside the IC package. In this case, as compared with the case where the drive circuit 14 is provided outside the control device 15, the signal transmission / reception wiring connecting the microcomputer 30 and the drive circuit 14 is dramatically shortened.

  The control device 15 includes at least a part of the control power supply circuit 13. For example, the control device 15 includes a control power IC 32 of the passive circuit unit 31 and the control power IC 32.

  A noise filter may be connected to the signal transmission / reception wiring inside the IC package. For example, a capacitor element may be used as the noise filter. At this time, one end of the capacitor element may be connected to the signal transmission / reception wiring, and the other end of the capacitor element may be connected to the ground wiring.

In this case, the PWM signal Sp and the PWM signal Sb can be transmitted with low noise from the microcomputer 30 to the drive circuit 14 through a short wiring formed inside the package of the control device 15. As a result, the first switching element Q ₁ and a second switching element Q ₂ can be accurately interlocked.

  In FIG. 5, the control power supply circuit 13 is a step-down converter circuit. For example, the control power supply circuit 13 is a buck converter circuit.

  In the control power supply circuit 13, the passive circuit unit 31 includes a plurality of passive elements constituting a buck converter circuit. Specifically, one of the passive elements is a choke coil L1. The other of the passive elements is a capacitor C1.

  In the control power supply circuit 13, the control power supply IC 32 includes a plurality of active elements constituting a buck converter circuit. Specifically, one of the active elements is an intelligent power device IPD. The intelligent power device IPD includes a MOSFET as a switching element. The other active element is a diode D1.

In the control power supply circuit 13, the output voltage is taken from the connection point between the choke coil L1 and the capacitor C1. The output voltage is used as the power supply voltage V _ACC . Supply voltage _{V ACC} is supplied to the drive circuit 14. The output voltage is input to the regulator REG. The regulator REG steps down the output voltage. The stepped down voltage is used as the power supply voltage V _DCC . The power supply voltage V _DCC is supplied to the microcomputer 30 and the like.

  As one modification of the control device 15, the ground electrodes of the analog circuit and the digital circuit may be connected to a common ground wiring (not shown) in the IC package inside the IC package. In this case, the ground wiring can be shortened.

  As another modification, the ground electrode of the analog circuit is connected to a first ground wiring (not shown) inside the IC package, and the ground electrode of the digital circuit is electrically connected to the first ground wiring inside the IC package. You may connect to the 2nd ground wiring (not shown) which is not carried out. In this case, the operation of the drive circuit 14 and the like can be prevented from affecting the operation of the microcomputer 30.

  Instead of the microcomputer 30, a digital signal processor (Digital Signal Processor: DSP) may be housed inside the control device 15. In the control device 15, a “digital arithmetic circuit” such as a microcomputer 30 or a DSP may perform arithmetic processing related to lighting control of the lighting device 4.

Embodiment 2. FIG.
FIG. 6 is a timing chart for explaining the LED turning-off operation when the lighting device according to Embodiment 2 of the present invention receives a turn-off instruction from the dimmer. In addition, the same code | symbol is attached | subjected to the same part as Embodiment 1, or an equivalent part. The description of this part is omitted.

Top of FIG. 6 is a timing chart showing a first variation of the output voltage V ₁ of the step-up chopper circuit 10. Second row from the top in FIG. 6 is a timing chart showing a first state of the switching element Q _1. The third stage from the top in FIG. 6 is a timing chart showing the second output voltage V ₂ of the buck converter circuit 11. Fourth stage from the top in FIG. 6 is a timing chart showing a second state of the switching element Q _2. The fifth row from the top in FIG. 6 is a timing chart showing changes in the LED current I _LED flowing through the light source module 3.

  In lighting device 4 of the first embodiment, when a turn-off instruction is received from dimmer 28, boost converter chopper circuit 10 starts the stop operation after buck converter circuit 11 starts the stop operation. On the other hand, in the second embodiment, when a turn-off instruction is received from the dimmer 28, the buck converter circuit 11 starts the stop operation after the boost chopper circuit 10 starts the stop operation.

Specifically, at time T1, the control device 15 receives a turn-off instruction from the dimmer 28. At this time, the controller 15 starts the stop operation first switching of the switching element Q _1. From time T1 until just before time T2, the control unit 15 gradually stops the first switching of the switching element Q _1. Specifically, the control unit 15 gradually reduces the duty ratio of the first switching of the switching element Q _1. At time T2, the control unit 15 completely stops the first switching element _{Q 1.}

As a result, during the period from time T1 to just before time T2, the first output voltage V ₁ of the boost chopper circuit 10 gradually decreases. At time T2, the _first output voltage V1 of the boost chopper circuit 10 becomes constant.

From time T1 until shortly before the time T3, the controller 15 switches to a fixed frequency controls the second switching of the switching element Q _2. At time T3, the control unit 15 starts the switching of the stop operation of the second switching element Q _2. At this time, the control unit 15 gradually stops the second switching of the switching element Q _2. Specifically, the control unit 15 gradually reduces the duty ratio in the second switching of the switching element Q _2.

As a result, during the period from time T1 until shortly before the time T3, the second output voltage V ₂ of the buck converter circuit 11 gradually decreases. Time T3 and beyond, the second output voltage _{V 2} of the buck converter circuit 11 gradually decreases. Thereafter, the second output voltage V ₂ of the buck converter circuit 11 is eventually zero.

For this reason, the LED current I _LED flowing through the light source module 3 gradually decreases from time T1 to immediately before time T3. Even after time T3, the LED current I _LED flowing through the light source module 3 gradually decreases. Thereafter, the LED current I _LED that flows through the light source module 3 finally becomes zero. In this case, the LED 5 is turned off with a natural fade-out.

Next, the operation of the control device 15 when receiving a turn-off instruction from the dimmer 28 will be described with reference to FIG.
FIG. 7 is a flowchart for explaining the operation of the control device when receiving a turn-off instruction from the dimmer in the lighting device according to Embodiment 2 of the present invention.

  In step S <b> 11, the control device 15 determines whether a turn-off instruction has been received from the dimmer 28. If the control device 15 has not received a turn-off instruction from the dimmer 28 in step S11, step S11 is repeated. When the control device 15 receives a turn-off instruction from the dimmer 28 in step S11, the process proceeds to step S12.

  In step S12, the control device 15 causes the step-up chopper circuit 10 to start a stop operation. Thereafter, the process proceeds to step S13. In step S13, the control device 15 causes the buck converter circuit 11 to start a stop operation. Thereafter, the operation ends.

According to the second embodiment described above, when a turn-off instruction is received from the dimmer 28, the buck converter circuit 11 starts the stop operation after the boost chopper circuit 10 starts the stop operation. Therefore, it is possible to decrease the output voltage V ₁ of the step-up chopper circuit 10. In this case, the lower limit value of the control range for reducing the light amount of the LED 5 can be lowered. As a result, without depending on the second minimum on time of the switching element Q _2, it is possible to turn off the LED5 natural fade.

Embodiment 3 FIG.
FIG. 8 is a timing chart for explaining the LED turning-off operation when the lighting device according to Embodiment 3 of the present invention receives a turn-off instruction from the dimmer. In addition, the same code | symbol is attached | subjected to the same part as Embodiment 1, or an equivalent part. The description of this part is omitted.

Top 8 (a) and FIG. 8 and (b) is a timing chart showing a first variation of the output voltage V ₁ of the step-up chopper circuit 10. Second row from the top in FIG. 8 (a) and 8 (b) is a timing chart showing a first state of the switching element Q _1. The third stage from the top of FIGS. 8A and 8B is a timing chart showing the second output voltage V ₂ of the buck converter circuit 11. Fourth stage from the top in FIG. 8 (a) and 8 (b) is a timing chart showing a second state of the switching element Q _2. The fifth row from the top of FIGS. 8A and 8B is a timing chart showing changes in the LED current I _LED flowing through the light source module 3.

  In lighting device 4 of the first embodiment, when a turn-off instruction is received from dimmer 28, boost converter chopper circuit 10 starts the stop operation after buck converter circuit 11 starts the stop operation. On the other hand, in the third embodiment, when a turn-off instruction is received from the dimmer 28, the buck converter circuit 11 is stopped and the drive of the boost chopper circuit 10 is maintained.

In FIG. 8A, the control device 15 receives a turn-off instruction from the dimmer 28 at time T1. At this time, the control unit 15 starts the switching of the stop operation of the second switching element Q _2. From time T1 until just before time T2, the control unit 15 gradually stops the second switching of the switching element Q _2. Specifically, the control unit 15 gradually reduces the duty ratio in the second switching of the switching element Q _2. At time T2, the control unit 15 completely stops the second switching element _{Q 2.}

As a result, during the period from time T1 to just before time T2, the second output voltage V ₂ of the buck converter circuit 11 gradually decreases. At time T2, the second output voltage _{V 2} 0 of the buck converter circuit 11.

After time T1, the controller 15 maintains the first switching of the switching element _{Q 1.}

As a result, after time T1, the first output voltage _{V 1} of the step-up chopper circuit 10 becomes constant.

Therefore, during the period from time T1 to just before time T2, LED current _{I LED} flowing to the light source module 3 gradually decreases following the second output voltage _{V 2.} At time T2, the LED current I _LED flowing through the light source module 3 becomes zero. In this case, the LED 5 is completely turned off at time T2 while fading out.

At time T3, the control device 15 receives a relighting instruction from the dimmer 28. At this time, the control unit 15 resumes the second switching of the switching element Q _2.

At this time, the first output voltage V ₁ of the step-up chopper circuit 10 is kept constant. As a result, at time T3 when the relighting instruction is received, the second output voltage V2 of the buck converter circuit 11 becomes a value equivalent to the value at time T1.

For this reason, at time T3, the LED current I _LED flowing through the light source module 3 becomes a value equivalent to the value at time T1. In this case, the LED 5 is lit in a state equivalent to the state at the time T1.

In FIG. 8B, the control device 15 receives a turn-off instruction from the dimmer 28 at time T1. At this time, the control unit 15 starts the switching of the stop operation of the second switching element Q _2. From time T1 until just before time T2, the control unit 15 gradually stops the second switching of the switching element Q _2. Specifically, the control unit 15 gradually reduces the duty ratio in the second switching of the switching element Q _2. At time T2, the control unit 15 completely stops the second switching element _{Q 2.}

As a result, during the period from time T1 to just before time T2, the second output voltage V ₂ of the buck converter circuit 11 gradually decreases. At time T2, the second output voltage _{V 2} 0 of the buck converter circuit 11.

Therefore, during the period from time T1 to just before time T2, LED current _{I LED} flowing to the light source module 3 gradually decreases following the second output voltage _{V 2.} At time T2, the LED current I _LED flowing through the light source module 3 becomes zero. In this case, the LED 5 is completely turned off at time T2 while fading out.

From time T1 until shortly before the time T3, the control device 15 maintains the first switching of the switching element Q _1.

As a result, during the period from time T1 until shortly before the time T3, the first output voltage V ₁ of the step-up chopper circuit 10 becomes constant.

After time T3, the control device 15 will then shorten the ON period first the switching element Q ₁ at a period fixed in a state where the second switching element Q ₂ has completely stopped.

As a result, after time T3, the first output voltage V ₁ of the step-up chopper circuit 10 will be reduced. The first output voltage V ₁ of the step-up chopper circuit 10 finally becomes zero.

Next, the operation of the control device 15 when receiving a turn-off instruction from the dimmer 28 will be described with reference to FIG.
FIG. 9 is a flowchart for illustrating the operation of the control device when receiving a turn-off instruction from the dimmer in the lighting device according to Embodiment 3 of the present invention.

  In step S <b> 21, the control device 15 determines whether a turn-off instruction has been received from the dimmer 28. If the control device 15 has not received a turn-off instruction from the dimmer 28 in step S21, step S21 is repeated. When the control device 15 receives a turn-off instruction from the dimmer 28 in step S21, the process proceeds to step S22.

  In step S22, the control device 15 causes the buck converter circuit 11 to start a stop operation. Thereafter, the process proceeds to step S23. In step S <b> 23, the control device 15 determines whether or not a relighting instruction has been received from the dimmer 28.

  If the control device 15 has not received a relighting instruction from the dimmer 28 in step S23, the process proceeds to step S24. In step S24, the control device 15 determines whether or not a preset time has elapsed.

If the time set in advance in step S24 has not elapsed, the process returns to step S23. If the time preset in step S24 has elapsed, the process proceeds to step S25. At step S25, the control unit 15, it will reduce the first output voltage _{V 1} of the step-up chopper circuit 10. Specifically, the control device 15 will then shorten the first ON period of the switching of the switching element Q _1. In this case, the boost chopper circuit 10 is finally stopped. Thereafter, the operation ends.

  When the control device 15 receives a relighting instruction from the dimmer 28 in step S23, the process proceeds to step S26. In step S <b> 26, the control device 15 resumes driving of the buck converter circuit 11. Thereafter, the operation ends.

  According to the third embodiment described above, when a turn-off instruction is received from the dimmer 28, the buck converter circuit 11 is stopped and the drive of the boost chopper circuit 10 is maintained. For this reason, when the relighting instruction is received from the dimmer 28, the LED 5 can be lighted quickly.

  It should be noted that when a turn-off instruction is received from the dimmer 28, the stop operation of the buck converter circuit 11 and the stop operation of the boost chopper circuit 10 may be started simultaneously.

  DESCRIPTION OF SYMBOLS 1 Lighting fixture, 2 AC power supply, 3 Light source module, 4 Lighting device, 5 LED, 6 Rectifier circuit, 7 Capacitor, 8 Resistance, 9 Resistance, 10 Boost chopper circuit, 11 Buck converter circuit, 12 Lamp connection detection circuit, 13 Control Power supply circuit, 14 drive circuit, 15 control device, 16 inductor, 17 diode, 18 capacitor, 19 resistor, 20 resistor, 21 diode, 22 inductor, 23 capacitor, 24 detection resistor, 25 resistor, 26 resistor, 27 digital interface circuit, 28 dimmers, 29 A / D conversion circuit, 30 microcomputer, 31 passive circuit unit, 32 control power supply IC

Claims (5)

A step-up chopper circuit that boosts a DC voltage obtained by rectifying an AC voltage from an AC power supply;
A buck converter circuit for stepping down a DC voltage boosted by the boost chopper circuit and lighting a light source by the stepped-down DC voltage;
A control device that stops the step-up chopper circuit and the buck converter circuit in a preset order when receiving a turn-off instruction from the dimmer;
Lighting device with   2. The lighting device according to claim 1, wherein the control device causes the boost chopper circuit to start a stop operation after the buck converter circuit starts a stop operation when receiving a turn-off instruction from the dimmer.   2. The lighting device according to claim 1, wherein the control device causes the buck converter circuit to start a stop operation after the boost chopper circuit starts a stop operation when receiving a turn-off instruction from the dimmer.   2. The lighting device according to claim 1, wherein the control device stops the buck converter circuit and maintains driving of the step-up chopper circuit when receiving a turn-off instruction from the dimmer.   The lighting fixture provided with the lighting device of any one of Claims 1-4.

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