JP6648502B2 - Lighting device and lighting equipment - Google Patents

Description

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

  Conventionally, for example, as described in Patent Document 1 below, in a lighting device that controls lighting of an LED, a circuit method combining a power factor improving type boost chopper circuit and a step-down chopper circuit has been found. According to Patent Literature 1, a method of obtaining a control power supply by operating a step-down chopper circuit has been found as an operation power supply of a control circuit for controlling lighting of an LED.

  In addition, as described in, for example, Patent Document 2 below, a technique has been found that suppresses a charging current of a capacitor, which is a characteristic of a lighting fixture, which is generated when a commercial power supply is turned on, that is, a so-called inrush current.

JP 2014-155300 A Japanese Patent No. 3551451

  In the lighting device according to Patent Document 1, the operation of the step-down chopper circuit is premised in order to obtain the operation power supply of the LED lighting control circuit. Therefore, the operation of the control circuit is affected by the output of the step-down chopper circuit. Was.

  The present invention has been made to solve the above-described problem, and has as its object to provide a lighting device capable of securing a control power supply for a control circuit of an output-side converter circuit.

  Further, the inventor of the present application has found that when a step-down chopper circuit (buck converter circuit) is used in a so-called discontinuous current mode, a negative potential is generated in a switching element of the buck converter circuit under a certain condition.

  Another object of the present invention is to provide a lighting device and a lighting apparatus that can suppress generation of a negative potential in a switching element of a buck converter circuit when a discontinuous current mode is used.

  In addition, the inventor of the present application examined the advantages of the flyback circuit and the buck converter circuit, and considered voltage specifications and the like for satisfying various uses required from a practical viewpoint. As a result, a lighting device and a lighting device which are resource-saving and beneficial to the user and which are excellent in practical use have been found.

  Still another object of the present invention is to provide a practical lighting device and a lighting fixture that can simultaneously realize downsizing and high functionality of the lighting device.

  Still another object of the present invention is to provide a small lighting device and a lighting fixture.

A lighting device according to a first aspect of the present invention includes a rectifier circuit that rectifies an AC voltage and outputs a DC voltage, a fly having a primary winding and a secondary winding, and the DC voltage being applied to one end of the primary winding. A back transformer, a first switching element that controls a current flowing through the primary winding, and a first control circuit that controls the first switching element so as to perform a power factor improvement operation that suppresses harmonics of the AC voltage. A flyback circuit that converts the DC voltage from the secondary winding and outputs a smoothed voltage that is a smoothed voltage; and a second switching element and a second control circuit that controls the second switching element. provided, and an output-side converter circuit for lighting the light source module by the output voltage obtained by stepping down the smoothed voltage by using the second switching element, said primary winding The voltage obtained from the auxiliary winding supplies a first control power to the first control circuit, for supplying a second control power source voltage taken out from the midpoint of the secondary winding to the second control circuit.

A lighting device according to a second aspect of the present invention includes a rectifier circuit for rectifying an AC voltage, and a flyback including a primary winding and a secondary winding, wherein the DC voltage output from the rectifier circuit is applied to one end of the primary winding. A transformer, a first switching element connected to the other end of the primary winding for controlling a current flowing through the primary winding, and the first switching element for performing a power factor improvement operation for suppressing harmonics of the AC voltage. A first control circuit for controlling the element, and performing only the step-down operation of the step-up operation and the step-down operation to reduce the DC voltage to a voltage lower than the peak voltage of the AC voltage to smooth the smoothed voltage. A flyback circuit for outputting the light, a light source module including a semiconductor light emitting element connected thereto, a second switching element and a second control circuit for controlling the second switching element, wherein the second switch is provided. Outputs an output voltage obtained by stepping down the smoothed voltage by driving the quenching device a current discontinuous mode, and a buck converter circuit for lighting the light source module in the output voltage, the auxiliary winding of the primary winding Is supplied to the first control circuit as a first control power supply, a voltage extracted from a middle point of the secondary winding is supplied to the second control circuit as a second control power supply, and the output voltage is It is set within a range of 1/2 or less of the smoothing voltage.

Luminaire according to the third invention includes a lighting device according to the inventions of the first or second.

  According to the first aspect, a control power supply can be secured in the control circuit of the output-side converter circuit by the operation of the input-side converter circuit, regardless of the state of the output-side converter circuit.

According to the second aspect, the electrical specifications are improved from a practical point of view while taking advantage of the flyback circuit and the buck converter circuit, so that the lighting device can be simultaneously miniaturized and highly functionalized. It is possible to provide an efficient lighting device.

According to the third invention, it is possible to mount the benefits of consuming lighting device to inventions of the first or 2 luminaire.

It is a circuit diagram showing a lighting device and a lighting fixture according to an embodiment of the present invention. It is a timing chart which shows operation of the lighting device concerning an embodiment of the invention.

  FIG. 1 is a circuit diagram showing a lighting device 10 and a lighting fixture 1 according to an embodiment of the present invention. The lighting device 10 is a so-called two-converter type conversion circuit, and corresponds to a flyback circuit 12 corresponding to an “input-side converter circuit” of the two converter circuits, and corresponds to an “output-side converter circuit” of the two converter circuits. And a buck converter circuit 14. The lighting device 10 includes a line filter L1, a rectifier circuit DB, capacitors C1, C4, C5, and resistors R2, R3, along with these converter circuits. The lighting fixture 1 according to the embodiment includes a lighting device 10 and a light source module 20 that is an LED light source unit that is lighted by the lighting device 10.

  The rectifier circuit DB converts the input voltage input from the commercial power supply AC into a pulsating DC voltage (hereinafter, also referred to as a rectified voltage). The capacitor C1 is connected in parallel to the output terminal of the rectifier circuit DB. The capacitor C1 serves as a power source when the flyback circuit 12 performs a switching operation between the output terminals of the rectifier circuit DB, and suppresses high-frequency ripple. Also, a line filter L1 is connected between the commercial power supply AC and the rectifier circuit DB to suppress high-frequency ripples.

  The flyback circuit 12 includes a flyback transformer T (hereinafter, also simply referred to as "transformer T"), a MOSFET Q1, which is a first switching element, a control IC 13, diodes D1, D4, a resistor R1, capacitors C2, C3. And A series circuit of the primary winding T1 of the transformer T and the MOSFET Q1 is connected in parallel to the capacitor C1. A Vg terminal of a control IC 13 for controlling and driving the flyback circuit 12 is connected to a gate of the MOSFET Q1. A drive signal for turning on / off the MOSFET Q1 is output from the Vg terminal of the control IC 13. The resistor R1 is connected to the Vcc terminal of the control IC 13. The resistor R1 is a resistor for generating a voltage for starting the control IC 13 from the output of the rectifier circuit DB.

  The control IC 13 has a VFB terminal as a terminal for detecting an FB (feedback) voltage used for feedback control of the flyback circuit 12 in addition to the Vcc terminal and the Vg terminal.

  One end of the capacitor C2 is connected to a connection point between the Vcc terminal of the control IC 13 and the resistor R1, and the other end of the capacitor C2 is connected to ground. The capacitor C2 stores charge from the output voltage of the rectifier circuit DB via the resistor R1. The capacitor C2 is used for stabilizing the voltage. The Vcc terminal is a control power terminal of the control IC 13, and when the commercial power AC is input, the control power is applied to the Vcc terminal of the control IC 13 via the resistor R1. As a result, the control IC 13 is activated and starts operating.

  The transformer T includes a primary winding T1, a secondary winding T2 that generates a voltage corresponding to a turn ratio with respect to the primary winding T1, and an auxiliary winding T3. The secondary winding T2 is a main output of the flyback circuit 12. The secondary winding T2 is connected to the anode of the diode D1, and the high-frequency voltage generated in the secondary winding T2 is rectified by the diode D1 and smoothed by the capacitor C4 to generate a smoothed voltage Vdc. The capacitor C4 is charged by the smoothed voltage Vdc.

  A voltage dividing circuit in which resistors R2 and R3 are connected in series is provided between both ends of the capacitor C4. The voltage dividing circuit including the resistors R2 and R3 is a detecting circuit that detects the voltage value of the smoothed voltage Vdc. The voltage divided by the resistors R2 and R3 is applied to the VFB terminal of the control IC 13. A capacitor C3 is connected to the VFB terminal, thereby stabilizing the detection voltage.

  One end of the auxiliary winding T3 of the transformer T is connected to the anode of the diode D4. The auxiliary winding T3 and the Vcc terminal of the control IC 13 are connected via the diode D4.

  The operation of the control IC 13 will be described. First, the commercial power supply AC is input, and the control IC 13 is activated. The control IC 13 outputs a drive signal to the gate of the MOSFET Q1 via the Vg terminal. Thereby, the MOSFET Q1 starts switching. When the MOSFET Q1 is turned on, a current flows through the primary winding T1 of the transformer T to store energy. When the MOSFET Q1 is turned off, the current is rectified by the diode D1 from the secondary winding T2 of the transformer T and a current flows.

  By repeating this switching operation, charges are stored in the capacitor C4. On the other hand, when the voltage value divided by the resistors R2 and R3 is input to the VFB terminal, the voltage across the capacitor 4 is detected by the control IC 13. The control IC 13 performs constant voltage control so that the voltage applied to the VFB terminal matches a preset target voltage. The control IC 13 performs feedback control of the switching of the MOSFET Q1 based on the voltage input to the VFB terminal so that the voltage applied to the capacitor C4 becomes constant.

  A voltage proportional to the smoothed voltage Vdc of the capacitor C4 is generated in the auxiliary winding T3 of the transformer T. The voltage generated in the auxiliary winding T3 is determined by the turn ratio between the secondary winding T2 and the auxiliary winding T3. The voltage generated in the auxiliary winding T3 is rectified by the diode D4 and supplied to the capacitor C2, and serves as an operation power supply of the control IC 13. Therefore, at the time of start-up, the control IC 13 is applied with a voltage by the resistor R1 and starts operation, but when the flyback circuit 12 operates stably, the control IC 13 operates with the voltage supplied from the auxiliary winding T3.

  Further, the control IC 13 performs a switching operation so that the ON time is constant within one cycle period of the AC voltage output from the commercial power supply AC. By this operation, power supply harmonics of the LED lighting device can be suppressed, and a high power factor can be obtained.

  The buck converter circuit 14 includes a MOSFET Q2 as a second switching element, an inductor L2, a diode D2, a capacitor C6, a microcomputer CPU 15, a drive circuit 16, a step-down circuit 17, and a resistor R4. The buck converter circuit 14 converts the smoothed voltage Vdc charged in the capacitor C4 by the flyback circuit 12 into a predetermined LED voltage to be applied to the light source module 20. A series circuit of MOSFET Q2 and diode D2 is connected in parallel to capacitor C4. A series circuit in which the inductor L2, the capacitor C6, and the resistor R4 are connected in this order is connected in parallel to the diode D2. The light source module 20 is connected in parallel to the capacitor C6.

  The source of MOSFET Q2 is connected to the cathode of diode D2, and the anode of diode D2 is connected to circuit ground. The diode D2 circulates the energy stored in the inductor L2 when the MOSFET Q2 is turned on when the MOSFET Q2 is off. Capacitor C6 smoothes the high-frequency voltage switched by MOSFET Q2. Power is supplied to the light source module 20 from the capacitor C6.

  The drive circuit 16 is connected to the gate of the MOSFET Q2. When the on / off signal from the drive circuit 16 is output to the gate of the MOSFET Q2, the MOSFET Q2 is turned on / off. The drive circuit 16 is connected to the microcomputer CPU15. The microcomputer CPU 15 detects a voltage corresponding to the LED current via the resistor R4. A current equal to the inductor L2 flows through the resistor R4, and the average current of the inductor L2 is equal to the LED current. The microcomputer CPU 15 detects the voltage converted by the resistor R4, and issues an operation command to the drive circuit 16 so that the detected voltage matches the target value, thereby adjusting the switching operation of the MOSFET Q2. Thereby, constant current control for controlling the LED current flowing through the light source module 20 to be constant can be performed.

  Charge is stored in the capacitor C5 from the middle point of the secondary winding T2 of the transformer T via the diode D3. After the voltage is rectified by the diode D3 from the middle point of the secondary winding T2, the capacitor C5 is stably charged with the rectified voltage, thereby generating the voltage Vcc2. The voltage Vcc2 is supplied to the drive circuit 16 as a control power. Further, after the voltage Vcc2 is stepped down by the step-down circuit 17, the stepped down voltage is supplied to the microcomputer CPU 15 as control power. Since the voltage Vcc2 is supplied from the middle point of the secondary winding T2, the magnitude of the voltage Vcc2 is determined by the smoothed voltage Vdc and the ratio of the number of turns at the middle point in the secondary winding T2.

  In the embodiment, the microcomputer CPU 15 is connected to the dimmer 22, and the microcomputer CPU 15 can also perform dimming control. Specifically, the microcomputer CPU 15 receives a dimming signal from the dimmer 22, and reads an operation target value of switching control for realizing a dimming rate according to the dimming signal from an internal memory of the microcomputer CPU 15. . The microcomputer CPU 15 sends an operation command to the drive circuit 16 based on the read operation target value. As a result, a current corresponding to the dimming rate flows through the light source module 20, so that the light source module 20 can be controlled to a desired brightness.

(Advantages of applying the unlit mode)
Here, consider the drive circuit 16 for controlling the lighting of the LED light source and the voltage Vcc2 which is a control power supply for operating the microcomputer CPU15. The voltage Vcc2 is obtained from the flyback circuit 12 as a control power supply. This control power supply voltage can be obtained even when the buck converter circuit 14 does not operate. For example, when a light-off mode command to turn off the light source module 20 is given to the microcomputer CPU 15 by an operation of an external device, the buck converter circuit 14 , The flyback circuit 12 operates by itself to obtain a control power supply. Therefore, the operation of the flyback circuit 12 is continued, the voltage is rectified by the diode D3 from the middle point of the secondary winding T2, and the capacitor C5 is charged. The voltage charged in the capacitor C5 is supplied to the drive circuit 16 as control power, and is also supplied to the microcomputer CPU 15 via the step-down circuit 17 as control power. As described above, since the microcomputer CPU 15 can reliably obtain the control power from the flyback circuit 12, there is no need to operate the buck converter circuit 14 when there is a light-off mode command from an external device. In other words, special control such as driving the buck converter circuit 14 at a low output enough to obtain the power of the microcomputer CPU 15 without turning on the light source module 20 becomes unnecessary. In the embodiment, since the buck converter circuit 14 only needs to be completely stopped, the light source module 20 can be surely turned off, and the control content in the light-off mode is simplified.

  There are also the following advantages when the light-off mode is canceled. When the light-off mode command signal for turning off the light source module 20 is given, the microcomputer CPU15 stops the switching of the MOSFET Q2. Also during the period when the MOSFET Q2 is turned off and the buck converter circuit 14 is stopped, the control IC 13 continues the switching control of the MOSFET Q1 so that the smoothed voltage Vdc is controlled at a constant voltage. However, the “continuation of switching control” of the MOSFET Q1 here means not only the control for continuing the ON / OFF operation of the MOSFET Q1 but also the fact that the voltage stored in the capacitor C4 is not substantially consumed due to the stop of the buck converter circuit 14. Control such as temporarily stopping the switching of the MOSFET Q1 while the charging of the capacitor C4 becomes unnecessary may be included. After the extinguishing mode is released, the microcomputer CPU 15 in the activated state immediately restarts switching of the MOSFET Q2 to drive the buck converter circuit 14, so that the light source module 20 can be quickly turned on again.

(Advantages related to inrush current)
Since the flyback circuit 12 generates the smoothed voltage Vdc by the transformer T, it is not necessary to suppress the rush current generated when the commercial power supply AC is input. The advantage of the flyback circuit 12 in this regard will be described below. There are the following two current loops flowing when the commercial power supply AC is input.
(1) Resistance R1 → capacitor C2
(2) Capacitor C1
First, the current is considered for the current loop of (2). As described above, the flyback circuit 12 controls the power factor to a high power factor. Therefore, the capacitor C1 has a capacitance (for example, an electrostatic capacity such as a power source for the flyback circuit 12 to operate at high frequency (for example, 40 kHz to 200 kHz)) 0.1 μF to 1 μF) is required. Further, the capacitor C1 does not need to have a capacitance large enough to smooth the voltage output from the rectifier circuit DB. Therefore, the current for charging the capacitor C1 does not become as large as the inrush current. Next, the current loop of (1) will be considered. Although the current suppressed by the resistor R1 is generated, the resistor R1 has a relatively large resistance value (for example, 100 kΩ) because it is a starting resistor, and the electric charge is stored in the capacitor C2 via the resistor R1 having the large resistance value. Is charged. Also in this case, as in the current loop of (2), no current flows as much as defined as an inrush current.

(Advantage of downsizing due to step-down operation only)
The flyback circuit 12 has an optimum output voltage that does not increase the size of components such as the MOSFET Q1 and the diode D1. The winding ratio of the primary winding T1 and the secondary winding T2 of the transformer T is generally designed to be the ratio of the voltage applied to the primary winding T1 to the voltage output from the secondary winding T2. Is considered good. A voltage obtained by rectifying the commercial power supply AC as described above is applied to the primary winding T1. As a general required specification of a lighting fixture, it is required that the commercial power supply AC can support a wide range, that is, it can support AC100V to 242V. For this reason, the flyback circuit 12 needs to convert a wide range (wide) voltage output from the rectifier circuit DB into a constant smoothed voltage Vdc. For example, if the flyback circuit 12 reduces the smoothed voltage Vdc to 141 V or less, which is the peak voltage of AC 100 V, the size of the components is not increased as described above. Conversely, if the smoothing voltage Vdc is set to 200 V, the flyback circuit 12 can operate in a step-down manner when the voltage is 200 V to 242 V AC, but operates in a step-up manner when the smooth voltage Vdc is 100 V AC. In this case, since a high voltage is applied to the MOSFET Q1 by a so-called flyback voltage generated at the time of turn-off, it is considered necessary to increase the size of components. From such a viewpoint, in order to prevent the components from increasing in size, a component having a withstand voltage performance that is deemed necessary only for the step-down operation of the flyback circuit 12 is selected as the MOSFET Q1 and the diode D1, and the flyback circuit 12 is stepped down. It can be designed for exclusive use.

  By using the flyback circuit 12 exclusively for the step-down operation, the following design can be performed in order to suppress an increase in the size of components.

  In order to prevent the flyback circuit 12 from performing a boosting operation, the circuit operation may be limited so that the flyback circuit 12 does not operate when an AC voltage that requires the boosting operation is input. For example, a terminal for detecting the peak value of the input AC voltage (the voltage of the capacitor C1) is provided in the control IC 13, and the flyback circuit 12 is configured so that the output voltage target value of the flyback circuit 12 is always smaller than the input AC voltage. May be designed. Alternatively, when the peak value of the input voltage (the voltage of the capacitor C1) is lower than the output voltage target value of the flyback circuit 12, the control IC is configured not to operate the flyback circuit 12 (to prevent the MOSFET Q1 from being turned on). It may be rare. That is, the control IC 13 may be configured not to operate the flyback circuit 12 when the peak voltage of the AC voltage is equal to or less than the predetermined voltage value. Alternatively, the control IC 13 may be configured to set the target value of the smoothed voltage Vdc smaller than the peak voltage of the AC voltage. Alternatively, the control IC 13 may be configured not to operate the flyback circuit 12 when the peak voltage of the AC voltage is lower than the target value of the smoothed voltage Vdc. Alternatively, control IC 13 may be configured to maintain MOSFET Q1 off when the peak voltage of the AC voltage is lower than the target value of smoothed voltage Vdc. The control IC 13 may be configured to control the MOSFET Q1 so that the smoothed voltage Vdc is set to 141 V or less regardless of the magnitude of the AC voltage.

  From the viewpoint of circuit design, for example, in selecting the diode D1 and the MOSFET Q1, the withstand voltage of the diode D1 and the withstand voltage of the MOSFET Q1 are the minimum withstand voltage values required to reduce the peak voltage to a predetermined smoothed voltage target value. You may make it become. Thus, by designing the flyback circuit 12 to have a minimum withstand voltage that can withstand the step-down operation, the flyback circuit 12 can be constructed with small components. The predetermined target value of the smoothing voltage may be 141V. As a result, even when the lighting device 10 is compatible with the so-called wide range of the commercial power supply of AC100V to 242V, the flyback circuit 12 performs the step-down operation at the time of AC200V to 242V, and does not perform the step-up operation at the time of AC100V.

(Advantages of damping vibration countermeasures)
FIG. 2 is a timing chart illustrating an operation of the lighting device 10 according to the embodiment of the present invention. The buck converter circuit 14 corresponding to the “output side converter circuit” will be described. As described above, the buck converter circuit 14 generates a voltage at which the light source module 20 as the LED light source is turned on based on the smoothed voltage Vdc output from the flyback circuit 12. At this time, the output voltage Vo at which the LED light source is turned on must be lower than the smoothed voltage Vdc. Further, when the buck converter circuit 14 is used in a general discontinuous current mode, the output voltage Vo is preferably set to be equal to or less than の of the smoothed voltage Vdc. Hereinafter, the reason will be specifically described with reference to FIG.

  FIG. 2 shows a switching operation of the MOSFET Q2 which is a switching element of the buck converter circuit 14. When the MOSFET Q2 is turned on, a current flows from the smoothed voltage Vdc of the capacitor C4 via the drain-source of the MOSFET Q2, and this current is limited by the inductor L2 (ton period in FIG. 2). When the MOSFET Q2 is turned off, no current flows from the smoothed voltage Vdc, but the energy stored in the inductor L2 is returned from the diode D2 (toff period in FIG. 2). When the energy stored in the inductor L2 is exhausted, a resonance phenomenon occurs due to the parasitic capacitance and the inductance of the inductor L2, and the potential at the connection point between the source of the MOSFET Q2 and the inductor L2 oscillates. As a result, a damped oscillation occurs in the source-drain voltage of the MOSFET Q2 (td period in FIG. 2).

  Here, attention is paid to the voltage between the source and the drain of the MOSFET Q2. First, during the toff period, since the return current flows through the diode D2, the source potential of the MOSFET Q2 is lower than the circuit ground by about 0.6 V in the forward voltage of the diode D2. Therefore, actually, a voltage of [Vdc-(-0.6 V)] is applied between the source and the drain of the MOSFET Q2. However, 0.6 V is sufficiently small with respect to the smoothed voltage Vdc and can be ignored. Therefore, it can be considered that the smoothed voltage Vdc is substantially applied between the source and the drain of the MOSFET Q2 during the toff period.

A damped oscillation occurs from the time period td when the energy of the inductor L2 is lost. The cycle of this damped oscillation is equal to the resonance frequency determined by the parasitic capacitance of MOSFET Q2 and the inductance of inductor L2. The magnitude of the vibration Vp-p is twice the output voltage Vo of the buck converter circuit 14. The magnitude Vp-p of the vibration is the maximum vibration width in the damped vibration during the td period, and is the width of the first vibration in FIG. The damped oscillation eventually disappears due to the DC resistance of the inductor L2. The disappearance of the damped oscillation causes the source-drain voltage of the MOSFET Q2 to converge to “the voltage V ′ obtained by subtracting the output voltage Vo from the smoothed voltage Vdc”. Each voltage is summarized as follows.
Vp−p = 2 × Vo
V ′ = Vdc−Vo

  “Vdc / 2” shown in FIG. 2 clearly indicates a value that is 倍 times the smoothed voltage Vdc. When the output voltage Vo is larger than half the smoothed voltage Vdc, the magnitude of the vibration Vp-p becomes larger than the smoothed voltage Vdc, and a negative potential is applied to the source-drain voltage of the MOSFET Q2. That is, the application of the negative potential causes a current to flow backward through the parasitic diode between the source and the drain, which is not preferable in practical use.

  In this regard, in the embodiment, the output voltage Vo is set to be equal to or less than 倍 of the smoothed voltage Vdc. Therefore, it is possible to prevent the magnitude of the damped oscillation Vp-p generated during the period td from becoming larger than the smoothed voltage Vdc. This makes it possible to suppress the application of a negative potential (reverse potential opposite to normal) to the source-drain voltage. The microcomputer CPU 15 of the buck converter circuit 14 adjusts the current flowing through the light source module 20 based on the dimming rate specified by the dimming signal. In such a dimming model, it is preferable that the output voltage Vo when the dimming rate is all light (100%) is set to be equal to or less than half the magnitude of the smoothing voltage Vdc. This makes it possible to realize all-light lighting even in a dimming model while avoiding practical problems.

  By employing the circuit configuration shown in the above embodiment, the flyback circuit 12 realizes the harmonic suppression function and the rush current suppression, which are general requirements of the lighting equipment, and performs the light source control of the dimming control and the extinguishing control by the buck converter circuit. 14 can be realized. As described in "Advantages Regarding Inrush Current", it is not necessary to provide a special circuit for suppressing inrush current, and the above general requirement specification can be satisfied with a circuit configuration with reduced parts. In addition, as described in “Advantages when the light-off mode is applied”, the light-off mode function can have higher performance without providing a special circuit. Further, the inventor of the present application has examined the voltages controlled by the respective circuits in the above-described circuit configuration. By finding each of the voltage specifications suitable for the light source module 20 described in “Advantages by Countermeasures for Damped Vibration”, a stable operation can be performed while suppressing an increase in the size of the entire circuit. Accordingly, the lighting device 10 and the lighting device 1 can be reduced in size, the lighting device 1 can be reduced in size, and their functions can be simultaneously improved. can do.

  In the embodiment, the advantage of applying the power-off mode to supplying power to the microcomputer CPU 15 from the middle point of the secondary winding T2 has been described. However, this configuration also has an advantage in a lighting device having no light-off mode, and specifically, has an advantage that power is supplied to the microcomputer CPU 15 quickly and stably regardless of the operation state of the buck converter circuit 14. .

Reference Signs List 1 lighting fixture, 10 lighting device, 12 flyback circuit, 13 control IC, 14 buck converter circuit, 15 microcomputer CPU, 16 drive circuit, 17 step-down circuit, 20 light source module, 22 dimmer, C1-C6 capacitor, D1- D4 diode, DB rectifier circuit, L1 line filter, L2 inductor, R1-R4 resistor, T transformer (flyback transformer), T1 primary winding, T2 secondary winding, T3 auxiliary winding, Vdc smoothing voltage, Vo output voltage

Claims (5)

A rectifier circuit that rectifies the AC voltage and outputs a DC voltage;
A flyback transformer including a primary winding and a secondary winding, the DC voltage being applied to one end of the primary winding, a first switching element for controlling a current flowing through the primary winding, and a harmonic of the AC voltage. A first control circuit that controls the first switching element so as to perform a power factor improvement operation that suppresses a wave, and converts the DC voltage from the secondary winding to a smoothed voltage that is a smoothed voltage. A flyback circuit to output,
An output-side converter circuit comprising a second switching element and a second control circuit for controlling the second switching element, and illuminating the light source module with an output voltage obtained by stepping down the smoothed voltage using the second switching element. When,
With
A voltage obtained from the auxiliary winding of the primary winding is supplied to the first control circuit as a first control power,
A lighting device for supplying a voltage extracted from a middle point of the secondary winding to the second control circuit as a second control power supply.   When a light-off mode command signal for turning off the light source module is given, the first control circuit continues to switch the first switching element, and the second control circuit stops the switching of the second switching element. The lighting device according to claim 1.   The lighting device according to claim 1, wherein the output-side converter circuit is a buck converter circuit. A rectifier circuit for rectifying the AC voltage;
A flyback transformer including a primary winding and a secondary winding, and a DC voltage output from the rectifier circuit is applied to one end of the primary winding; and a flyback transformer connected to the other end of the primary winding and flowing through the primary winding. A first switching element that controls a current; and a first control circuit that controls the first switching element so as to perform a power factor improvement operation that suppresses harmonics of the AC voltage. A flyback circuit that outputs a smoothed voltage that is a voltage obtained by lowering the DC voltage to be lower than the peak voltage of the AC voltage by performing only the step-down operation, and
A light source module including a semiconductor light emitting element is connected, a second switching element and a second control circuit for controlling the second switching element are provided, and the smoothing voltage is reduced by driving the second switching element in a discontinuous current mode. A buck converter circuit that outputs a stepped-down output voltage and turns on the light source module with the output voltage;
With
A voltage obtained from the auxiliary winding of the primary winding is supplied to the first control circuit as a first control power,
A voltage taken out from the middle point of the secondary winding is supplied to the second control circuit as a second control power,
A lighting device for setting the output voltage within a range equal to or less than 1/2 of the smoothed voltage. Luminaire comprising a lighting device according to any one of claims 1-4.

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