JP2019212358A - Lighting device and illumination apparatus - Google Patents

Abstract

To reduce stress applied to an element constituting a circuit, in a lighting device that turns on a light-emitting element by receiving power supply from a phase control type dimmer.SOLUTION: A lighting device includes: a power conversion circuit receiving power supply from a phase control type dimmer and supplying power to a light-emitting element; a constant current circuit flowing constant current through the light-emitting element; and a voltage feedback circuit to output, to the power conversion circuit, a control signal for controlling the output voltage of the power conversion circuit to a predetermined target value. The lighting device also includes a control section to temporarily reduce the power supply amount of the power conversion circuit when the dimming speed of the dimmer exceeds a predetermined threshold.SELECTED DRAWING: Figure 5

Description

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

  A lighting device including a light emitting element such as an LED is provided with a lighting device that turns on the light emitting element (see, for example, Patent Document 1). In addition, a dimmer may be connected to the lighting fixture in order to adjust the light amount of the light emitting element (see the patent document). Some of these dimmers perform so-called fade-in control that, when activated, gradually increases the amount of light of the lighting fixture to a preset amount of light over a predetermined time.

Japanese Patent No. 6123132

  By the way, depending on the specification of the dimmer, there are some cases where the rate of increase in the amount of light during the fade-in control is relatively fast. In addition, the amount of light may be suddenly increased by the user's operation of the dimmer.

  Thus, when the amount of light is suddenly changed, as will be described later, there is a possibility that a rapid rise in voltage occurs in the lighting device. A sudden rise in voltage may also increase the stress applied to the elements (for example, capacitors) constituting the circuit.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce stress applied to an element (for example, a capacitor) constituting a circuit in a lighting device that turns on a light emitting element by receiving power supply from a phase control type dimmer. And

  In order to solve the above problems, a lighting device according to the present disclosure includes a power conversion circuit that receives power supply from a phase control dimmer and supplies power to a light emitting element, and a constant current that flows through the light emitting element. A current circuit; a voltage feedback circuit that outputs a control signal for controlling the output voltage of the power conversion circuit to a predetermined target value; and a dimming speed of the dimmer exceeds a predetermined threshold value. And a controller that temporarily reduces the amount of power supplied to the power conversion circuit.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce the stress given to the element (for example, capacitor | condenser) which comprises the circuit of a lighting device.

The structure of the lighting fixture of this embodiment is shown. The structural example of a lighting fixture is shown with a block diagram. The structural example of a power converter circuit is shown. It is a wave form diagram which shows operation | movement of a phase detection circuit. The concrete circuit structure of a current control circuit is shown. The structure of a current drawing part is shown. Fig. 2 shows a part of the circuit of a luminaire. It is a wave form diagram which shows operation | movement of each part of a lighting fixture. It is waveform diagrams, such as the electric current of the light emitting element at the time of lighting a lighting fixture. It is a wave form diagram, such as a current of a light emitting element at the time of operating a dimmer. The modification of a conduction angle detection part is shown. The other modification of a conduction angle detection part is shown. Another modification of a conduction angle detection part is shown.

<Embodiment>
FIG. 1 shows a configuration of a lighting fixture 1 according to the present embodiment. The luminaire 1 forms a series circuit with the dimmer 2. This series circuit is connected between both ends of the commercial power supply 10 (AC power supply). The dimmer 2 adjusts the power supplied from the commercial power supply 10 to the lighting fixture 1 by phase-controlling the power supply voltage (AC voltage) of the commercial power supply 10.

<Configuration of lighting apparatus 1>
The structural example of the lighting fixture 1 is shown with a block diagram in FIG. As shown in FIG. 2, the luminaire 1 includes an input filter circuit 1a, a power conversion circuit 1b, a phase detection circuit 1c, a dimming circuit 1d, a current control circuit 1e, a bleeder circuit 1f, and a conduction angle detection unit 100 (control unit). And a light source unit 1h (light emitting element). In the luminaire 1, a portion excluding the light source unit 1 h is a lighting device that turns on the light emitting element.

  The input filter circuit 1a includes a capacitor, an inductor, and the like, and has a function of suppressing noise propagating to the power supply line and noise radiating to the space.

  FIG. 3 shows a configuration example of the power conversion circuit 1b. As shown in FIG. 3, the power conversion circuit 1b includes a rectifier circuit DB1, capacitors C1 and C2, a transformer T1, switching elements Q1a and Q1b, a control circuit K1, and a diode D1, and constitutes a non-insulated flyback converter. To do. The power conversion circuit 1b constitutes a quasi-resonant circuit for reducing loss and noise, and further has a power factor improving function for improving the power factor of the commercial power source 10.

  First, the rectifier circuit DB1 is configured by full-bridge connection of diodes, and full-wave rectifies the power supply voltage of the commercial power supply 10.

  The capacitor C1 is a film capacitor connected between the output terminals of the rectifier circuit DB1, and suppresses a voltage / current spike generated when the switching elements Q1a and Q1b are turned on. The capacitor C1 has a smaller capacity than the smoothing capacitor and does not take into account the smoothing action. That is, the power conversion circuit 1b does not include a smoothing capacitor having a large capacity such as an electrolytic capacitor in the input means, and does not constitute a capacitor input type power supply circuit.

  The transformer T1 includes a primary winding N1, a secondary winding N2, and a tertiary winding N3. The windings of the transformer T1 are magnetically coupled to each other. In this example, a series circuit of a primary winding N1 and a switching element Q1b is connected between output terminals of the rectifier circuit DB1, and a diode D1 is inserted at one end of the secondary winding N2. A smoothing capacitor C2 is connected in parallel to the series circuit of the secondary winding N2 and the diode D1. Further, in the transformer T1, a switching element Q1a is connected in parallel with the switching element Q1b at an intermediate position of the primary winding N1.

  The control circuit K1 conducts the current flowing from the commercial power supply 10 to the primary winding N1 by driving the other element on and off while either one of the switching element Q1a or the switching element Q1b is turned off. ·Cut off.

  For example, when switching element Q1b is turned on / off while switching element Q1a is turned off, when switching element Q1b is turned on, current flows in the entire primary winding N1 (number of turns = N11 + N12) and the series circuit of switching element Q1b. The magnetic energy is accumulated throughout the primary winding N1. Next, when the switching element Q1b is turned off, an induced voltage is generated in the secondary winding N2 due to the magnetic energy of the primary winding N1, and a voltage is generated between both ends of the capacitor C2.

  Then, the control circuit K1 controls the switching element Q1b to control the output of the power conversion circuit 1b to a predetermined value, and further improves the power factor of the commercial power supply 10. Note that the power factor correction operation by the flyback converter is a well-known technique and will not be described in detail. In the following description, a mode in which the switching element Q1b is turned on / off while the switching element Q1a is turned off is referred to as a normal operation mode.

  On the other hand, when switching element Q1a is turned on / off while switching element Q1b is turned off, when switching element Q1a is turned on, winding N11 (number of turns N11) of primary winding N1 and switching element Q1a A current flows through the series circuit, and magnetic energy is accumulated in the winding N11. Next, when the switching element Q1a is turned off, an induced voltage is generated in the secondary winding N2 due to the magnetic energy of the winding N11, and a voltage is generated across the capacitor C2. At this time, the voltage generated between both ends of the capacitor C2 becomes a small value compared to the case where the switching element Q1b is driven on / off while the switching element Q1a is turned off. That is, the effective ratio of the secondary winding to the primary winding can be lowered by causing the control circuit K1 to drive the switching element Q1a on and off while the switching element Q1b is turned off. Thereby, when the control circuit K1 performs switching control of the switching element Q1a at the same cycle as in the normal operation mode, the power supply amount of the power conversion circuit 1b can be reduced as compared with the normal operation mode. In the following description, a mode in which the switching element Q1a is turned on / off while the switching element Q1b is turned off is referred to as a low power mode.

  The light source unit 1h is composed of a plurality of LED elements or organic EL elements connected in series or in parallel, and is connected between both ends of the capacitor C2.

  Returning to FIG. 2, the phase detection circuit 1c is connected to the cathodes of the diodes Da and Db each having an anode connected to each input terminal of the rectifier circuit DB1 (see FIG. 3), and the dimmer 2 (see FIG. 1). The voltage Vd (full-wave rectified voltage Vd) obtained by full-wave rectifying the power supply voltage phase-controlled by is input. The phase detection circuit 1c detects the conduction angle of the power supply voltage input to the lighting fixture 1 (conduction angle of the full-wave rectified voltage Vd), and a binary signal (with a duty ratio corresponding to the detected conduction angle ( The duty signal S1) is output to the dimming circuit 1d.

  Specifically, in the phase detection circuit 1c, a full-wave rectified voltage Vd (see FIG. 4A) obtained by full-wave rectifying the power supply voltage is input via the diodes Da and Db. The phase detection circuit 1c compares the full-wave rectified voltage Vd with a threshold value Vt2, thereby generating a binary duty signal S1 set to a duty ratio corresponding to the conduction angle. The duty signal S1 is at the L level when the voltage value of the power supply voltage is greater than or equal to the threshold value Vt2, and is at the H level when the voltage value of the power supply voltage is less than the threshold value Vt2 (see FIG. 4B).

  The dimming circuit 1d sets a target value of the load current corresponding to the duty ratio of the duty signal S1, and outputs a voltage signal (target signal S2) corresponding to the target value of the load current to the current control circuit 1e.

  The current control circuit 1e includes a constant current circuit including a FET element Q91, a resistor R91, and an operational amplifier OP91. This constant current circuit detects a load current flowing through the light source unit 1h by a resistor R91 connected in series with the light source unit 1h. In addition, the constant current circuit acquires a target value of the load current based on the target signal S2 input from the dimming circuit 1d and performs constant current control so that the load current matches the target value. In the current control circuit 1e, the operational amplifier OP92, the resistors R96 and R97, and the control circuit K1 constitute a constant voltage circuit. This constant voltage circuit detects the voltage of the capacitor C2 based on the voltage Vq (that is, Vf + Vq, where Vf is the voltage across the light source unit 1h). The constant voltage circuit outputs a feedback signal S3 (for example, an error between Vq and the target value) based on the voltage Vq and the target value set by the resistors R96 and R97 to the control circuit K1 (see FIG. 3).

  The control circuit K1 performs constant current control so that the voltage of the capacitor C2 matches the target value by setting the conduction period (ON period) of the switching element Q1 according to the feedback signal S3.

  FIG. 5 shows a specific circuit configuration of the current control circuit 1e. The current control circuit 1e includes a series circuit of an FET element Q91 and a resistor R91 connected in series to the light source unit 1h. The drain of the FET element Q91 is connected to the light source unit 1h, and the source of the FET Q91 is connected to the resistor R91. The output of the operational amplifier OP91 is connected to the gate of the FET element Q91, and further connected to a later-described fourth control voltage Vcc4 via a resistor R93. Further, a resistor R92 is connected between the inverting input and the output of the operational amplifier OP91, and the inverting input of the operational amplifier OP91 is connected to the source of the FET element Q91.

  The non-inverting input of the operational amplifier OP91 is connected to the low-voltage side output of the power conversion circuit 1b via the capacitor C91, and further the target signal S2 is input via the resistor R94. That is, the RC circuit 90 formed by the resistor R94 and the capacitor C91 is connected to the non-inverting input of the operational amplifier OP91. The operational amplifier OP91 functions as a comparator that compares the current If flowing through the light source unit 1h with the target signal S2 indicating the target value of the current If.

  The inverting input of the operational amplifier OP92 is connected to the drain of the FET element Q91 via the resistor R95. The non-inverting input of the operational amplifier OP92 divides a fourth control voltage Vcc4 described later by a series circuit of resistors R96 and R97. Pressed voltage is input. Further, a resistor R98 is connected between the inverting input and the output of the operational amplifier OP92.

  When the light source unit 1h is composed of an LED element or an organic EL element, a large ripple occurs in the load current flowing through the light source unit 1h due to the ripple of the output voltage of the power conversion circuit 1b (the voltage across the capacitor C2). Cause flickering.

  Therefore, by configuring the current control circuit 1e as shown in FIG. 5, the load current flowing through the light source unit 1h is reduced. Specifically, in the current control circuit 1e, the output voltage of the operational amplifier OP91 decreases when the load current increases relative to the target value (target signal S2), and the load current is relative to the target value. It increases when it decreases.

  That is, the operational amplifier OP91 controls the FET element Q91 in the direction in which the drain-source resistance of the FET element Q91 increases when the load current increases relative to the target value. Further, the operational amplifier OP91 controls the FET element Q91 in the direction in which the drain-source resistance of the FET element Q91 decreases when the load current decreases relative to the target value. That is, the FET element Q91 and the operational amplifier OP91 constitute a “constant current circuit” that allows a constant current to flow to the light source unit 1h (light emitting element).

  In this configuration, since the ripple of the output voltage of the power conversion circuit 1b is applied to both ends of the series circuit of the FET element Q91 and the resistor R91, the voltage across the light source unit 1h is substantially constant with the ripple reduced. A voltage is applied.

  Furthermore, the operational amplifier OP92 has a function of controlling the power supplied to the light source unit 1h. The operational amplifier OP92 outputs the feedback signal S3 to the control circuit K1 so that the voltage across the series circuit of the FET element Q91 and the resistor R91 becomes the target voltage.

  That is, the operational amplifier OP92 constitutes a “voltage feedback circuit” that outputs a control signal S3 for controlling the output voltage of the power conversion circuit 1b to a predetermined target value to the power conversion circuit 1b. Thus, the operational amplifier OP92 monitors the voltage across the series circuit of the FET element Q91 and the resistor R91, and outputs the feedback signal S3 to the control circuit K1, so that the load current is set to the target value in the lighting fixture 1. Constant current control is performed so as to match.

  Further, as described above, the luminaire 1 is provided with the conduction angle detection unit 100. The conduction angle detection unit 100 includes a microcomputer and a memory device that stores software for operating the microcomputer. The conduction angle detection unit 100 has a function of detecting the amount of change in the conduction angle (described later) of the dimmer 2.

  Specifically, the conduction angle detection unit 100 determines the amount of phase change (that is, dimming) of the input voltage to the power conversion circuit 1b based on the amount of change in duty in the output waveform of the phase detection circuit 1c (that is, the waveform of the duty signal S1). Change amount of the conduction angle of the vessel 2). Then, the conduction angle detection unit 100 outputs the phase change amount as the detection signal S4 to the control circuit K1.

  Returning to FIG. 3, the control circuit K1 drives the switching elements Q1a and Q1b on and off based on the detection signal S4 received from the conduction angle detector 100. Specifically, the control circuit K1 controls the switching elements Q1a and Q1b when the phase change amount of the input voltage to the power conversion circuit 1b, that is, the dimming speed of the dimmer 2 exceeds a predetermined threshold value. Thus, the normal operation mode is shifted to the low power mode, and the power supply amount of the power conversion circuit 1b is temporarily reduced.

  Note that the method of shifting from the normal operation mode to the low power mode and temporarily reducing the power supply amount of the power conversion circuit 1b is not limited to the above method.

  For example, in FIG. 3, the switching element Q1a may be omitted, and the control circuit K1 may intermittently control the switching element Q1b in the low power mode, or temporarily stop the control of the switching element Q1b. Also in this method, the power supply amount of the power conversion circuit 1b can be temporarily reduced.

  Instead of omitting the switching element Q1a, the switching circuit Q1b is omitted, and the control circuit K1 intermittently controls the switching element Q1a in the low power mode, or temporarily stops the control of the switching element Q1a. However, the same effect can be obtained.

  The bleeder circuit 1 f is a circuit provided for the purpose of supplying power to the dimmer 2 during the operation of the dimmer 2.

  First, as shown in FIG. 6, the bleeder circuit 1f includes diodes Da and Db each having an anode connected to each input terminal of the rectifier circuit DB1, cathodes of the diodes Da and Db, and a low voltage side of the rectified output of the rectifier circuit DB1. And a current drawing portion 1g connected between the two. That is, the bleeder circuit 1 f can be considered equivalent to a bleeder circuit 1 f connected in parallel between the input ends of the lighting fixture 1.

  FIG. 6 shows the configuration of the current drawing unit 1g. In the current drawing unit 1g, a series circuit of an FET element Q71, a resistor R71, and a resistor R72 is connected between the cathodes of the diodes Da and Db and the low-voltage side of the rectified output of the rectifier circuit DB1. The drain of the FET element Q71 is connected to the cathodes of the diodes Da and Db. The source of the FET element Q71 is connected to a series circuit of resistors R71 and R72. Furthermore, the gate of the FET element Q71 is connected to the phase detection circuit 1c. A Zener diode ZD71 is connected between the gate of the FET element Q71 and the low-voltage side of the rectified output of the rectifier circuit DB1.

  Moreover, the lighting fixture 1 is provided with 1st-4th control power supply circuits PS1-PS4 in order to supply a control voltage to each part.

  As shown in FIG. 3, the first control power supply circuit PS1 includes a series circuit of a tertiary winding N3 of a transformer T1 and a diode D2. A capacitor Ca is connected in parallel to the series circuit of the tertiary winding N3 and the diode D2. The voltage Vcc across the capacitor Ca becomes the first control voltage Vcc1 by the power supplied from the tertiary winding N3. A discharging resistor Ra is connected between both ends of the capacitor Ca.

  Specifically, when the power conversion circuit 1b is operating and the switching element Q1 (one of Q1a and Q1b) is in an on state, magnetic energy is accumulated in the primary winding N1, and then the switching element Q1 (Q1a, Q1a, When both Q1b) are turned off, an induced voltage is generated in the tertiary winding N3 by the magnetic energy of the primary winding N1. Due to this induced voltage, the capacitor Ca is charged via the diode D2, and the first control voltage Vcc1 is generated across the capacitor Ca. That is, the voltage Vcc across the capacitor Ca becomes the first control voltage Vcc1 by the power supplied from the first control power supply circuit PS1.

  As shown in FIG. 7, the second control power supply circuit PS2 includes a resistor R21, a Zener diode ZD21, a transistor Q21, a capacitor C21, and a diode D21. The full-wave rectified voltage Vd is applied to the series circuit of the resistor R21 and the Zener diode ZD21.

  The base of the transistor Q21 is connected to the midpoint of connection between the resistor R21 and the Zener diode ZD21, and the full-wave rectified voltage Vd is applied to the collector of the transistor Q21. Further, the emitter of the transistor Q21 is connected to the low voltage side of the rectified output of the rectifier circuit DB1 via the capacitor C21, and further connected to the positive electrode of the capacitor Ca via the diode D21.

  As shown in FIG. 3, the third control power supply circuit PS3 includes resistors R11 and R12, a Zener diode ZD11, a transistor Q11, and a capacitor C11. A series circuit of the resistor R11 and the Zener diode ZD11 is connected in parallel to the secondary-side capacitor C2 of the power conversion circuit 1b. The base of the transistor Q11 is connected to the midpoint of connection between the resistor R11 and the Zener diode ZD11, and the collector of the transistor Q11 is connected to the positive electrode of the capacitor C2. Further, the emitter of the transistor Q11 is connected to the negative electrode of the capacitor C2 via the capacitor C11, and the resistor R12 is connected in parallel to the capacitor C11.

  In the third control power supply circuit PS3, the sum of the base-emitter voltage of the transistor Q11 and the voltage across the capacitor C11 matches the Zener voltage of the Zener diode ZD11. The voltage across the capacitor C11 is constant voltage controlled and becomes the third control voltage Vcc3. That is, the third control power supply circuit PS3 converts the voltage across the capacitor C2 into the third control voltage Vcc3 and outputs it.

  As shown in FIG. 7, the fourth control power supply circuit PS4 includes capacitors C31 and C32 and a three-terminal regulator REG31. A capacitor C31 is connected in parallel to the input side of the three-terminal regulator REG31, and a capacitor C32 is connected in parallel to the output side of the three-terminal regulator REG31.

<Dimmer>
The dimmer 2 is a phase control type dimmer. The dimmer 2 includes a capacitor C81, an inductor L81, and a triac Q81 as shown in FIG. The capacitor C81 and the inductor L81 constitute a noise prevention filter. The triac Q81 is a bidirectional switching element having a self-holding function.

  The capacitor C81 is connected between the input ends of the dimmer 2, and a series circuit of a triac Q81 and an inductor L81 is connected in parallel to the capacitor C81. Then, when the triac Q81 is in a conducting state, AC power is supplied from the commercial power supply 10 to the power conversion circuit 1b.

  The dimmer 2 includes a power supply unit 4. The power source unit 4 generates a control power source for operating each unit (a dimming control unit 3 described later) of the dimmer 2 and is connected in parallel to the triac Q81.

  The power supply unit 4 includes a diode D81, a capacitor C82, a power supply circuit K81, and a capacitor C83.

  The diode D81 is connected to the power supply line from the lighting fixture 1. The capacitor C82 is connected in parallel to the triac Q81 via the diode D81. The power supply circuit K81 converts the voltage across the capacitor C82 into a control voltage Vs and outputs it. The capacitor C83 is a smoothing capacitor connected between the output terminals of the power supply circuit K81. Here, the low voltage terminal of the capacitor C83 is connected to the circuit ground.

  Furthermore, the dimmer 2 includes a dimming control unit 3. The dimming control unit 3 includes a synchronization signal generation unit K82, a control circuit K83, and an operation unit K84. The dimming control unit 3 performs phase control to vary the conduction angle of the power supply voltage of the commercial power supply 10 by turning on the triac Q81. The amount of change in the conduction angle of the dimmer 2 can be considered as the speed of dimming.

  First, the synchronization signal generation unit K82 is connected to the power supply line (the anode side of the diode D81) from the luminaire 1 via the diode D82. The synchronization signal generation unit K82 has a ground terminal connected to the circuit ground, generates a synchronization signal shown in FIG. 8A based on the phase of the power supply voltage supplied from the commercial power supply 10, and supplies the synchronization signal to the control circuit K83. Output.

  Specifically, the synchronization signal generation unit K82 compares the power supply voltage of the commercial power supply 10 with a predetermined threshold Vt1 by detecting the power supply voltage of the commercial power supply 10 via the diode D82, and the power supply voltage sets the threshold Vt1. A synchronization signal is generated with the period exceeding the H level. That is, the synchronization signal rises when the power supply voltage exceeds the threshold value Vt1, and falls when the power supply voltage falls below the threshold value Vt1. 8A to 8C, the broken line indicates the waveform of the power supply voltage of the commercial power supply 10.

  The control circuit K83 generates a trigger signal for turning on the triac Q81 based on the synchronization signal provided from the synchronization signal generation unit K82 and the dimming signal provided from the operation unit K84 (see FIG. 8B). The rise and fall of the trigger signal are both determined with reference to the rise of the synchronization signal.

  The control circuit K83 outputs a trigger signal to the gate of the triac Q81, whereby a drive current flows through the gate of the triac Q81 and the triac Q81 becomes conductive. Here, the control circuit K83 employs a so-called DC trigger method in which a trigger signal for turning on the triac Q81 is continuously supplied for a predetermined period of time during which the triac Q81 is turned on to be conducted.

  That is, the dimming control unit 3 controls the phase of the power supply voltage applied to the lighting fixture 1 by turning on the triac Q81 using the DC trigger method. The dimmer 2 is activated when the user turns on a switch provided in the dimmer 2. When the dimmer 2 is activated, it performs so-called fade-in control in which the light amount of the luminaire 1 is increased to a preset light amount over a predetermined time (for example, several seconds).

<Operation of lighting apparatus 1>
In the luminaire 1, the initial state (when the luminaire 1 is controlled to be turned off by the dimmer 2) is set to the normal operation mode, that is, the switching element Q <b> 1 a is turned off. Then, when the user turns on the dimmer 2, supply of AC power to the luminaire 1 is started. At this time, the dimmer 2 performs the fade-in control.

  In addition, when the user turns on the dimmer 2, in the lighting fixture 1, the conduction angle detection unit 100 starts operating. That is, the conduction angle detection unit 100 obtains the phase change amount of the input voltage to the power conversion circuit 1b based on the duty change amount in the waveform of the duty signal S1.

  Depending on the specifications of the dimmer 2, there is a relatively fast increase in the amount of light during fade-in control. Therefore, when the phase change amount (change amount of the conduction angle) detected by the conduction angle detection unit 100 exceeds a predetermined threshold Thv depending on the specifications of the dimmer 2 (that is, the dimming speed). May exceed a predetermined value). Further, even when the user performs dimming rapidly in the increasing direction of the light amount, the change amount of the conduction angle may exceed the threshold value Thv.

  As described above, when the phase change amount of the input voltage exceeds the threshold Thv, the conduction angle detection unit 100 has exceeded the predetermined dimming speed by the dimmer 2 (abrupt dimming in the increasing direction of the light amount). The control circuit K1 shifts to control in the low power mode and temporarily reduces the power supply amount of the power conversion circuit 1b. For example, the control circuit K1 performs switching control of the switching element Q1a with the switching element Q1b turned off. Alternatively, the control circuit K1 switches the switching element Q1 (Q1a, Q1b) performing switching control in the normal operation mode to intermittent control or temporarily stops the switching element Q1.

  Here, the drain voltage of the FET element Q91 (the voltage across the series circuit of the FET element Q91 and the resistor R91) is Vq, the voltage across the light source unit 1h is Vf, the sum of Vq and Vf is V02, and the current flows through the light source unit 1h. (Load current) is defined as If, and the voltage of the feedback signal S3 is defined as VFB. Then, the waveform diagram of the voltage V02, the current If, etc. in the low power mode of the lighting fixture 1 is as shown in FIG. 9B.

  In FIG. 9A, the voltage V02, the current If, etc. in the normal operation mode are also shown for comparison. The characteristics of the normal operation mode (current and voltage characteristics) correspond to the characteristics of the conventional lighting fixture. Hereinafter, for convenience of explanation, an example in which the normal operation mode is fixed will be described as an example of a conventional lighting fixture.

  As can be seen from FIG. 9A, in the conventional lighting fixture, the current If increases at a speed according to the dimming speed of the dimmer 2. And in the conventional lighting fixture, after the dimmer 2 starts, the voltage V02, Vq, and the rapid rise of VFB have occurred. Such a sudden rise occurs because a predetermined time is required until the current If (load current) of the light source unit 1h rises to the target value, and there is a period during which the power conversion circuit 1b cannot fully reduce the power. Because it does.

  On the other hand, in the lighting fixture 1 of this embodiment, as shown in FIG.9 (b), compared with the conventional lighting fixture, the sharp rise of the voltage V02 can be suppressed, As a result, the rise of Vq and VFB is increased. The width is also getting smaller. For example, in FIG. 9, the VFB rising width Vfbb in the present embodiment is smaller than the VFB rising width Vfba in the conventional lighting fixture.

  FIG. 10 illustrates a waveform of current or the like when the user operates the dimmer 2 to suddenly change the light amount from the minimum light amount (the state with the smallest light amount) to the maximum light amount. Also in FIG. 10, (a) shows the characteristic of the conventional lighting fixture, (b) has shown the characteristic of this embodiment. In the lighting fixture 1 of this embodiment, as shown in FIG.10 (b), compared with the conventional lighting fixture, the sharp raise of the voltage V02 can be suppressed. As a result, in the lighting fixture 1 of the present embodiment, as shown in FIG. 10, the width of rise of Vq and VFB is also reduced.

<Effect of this embodiment>
As described above, in the present embodiment, the control circuit K1 is controlled so as to temporarily reduce the power supplied to the power conversion circuit 1b when the dimming is relatively performed in the direction of increasing the amount of light. To do. Thereby, in this embodiment, it is difficult for the voltages V02, Vq, and VFB to rapidly rise. That is, according to the present embodiment, it is possible to reduce the stress applied to the circuit elements (for example, the capacitor C2) constituting the lighting device.

<< First Modification of Embodiment >>
FIG. 11 shows a modification of the conduction angle detection unit 100. That is, in this example, the configuration of the conduction angle detection unit 100 is different from that of the embodiment.

  As shown in FIG. 11, the conduction angle detection unit 100 receives a voltage Vd (full wave rectified voltage Vd) obtained by full-wave rectifying the power supply voltage phase-controlled by the dimmer 2. The conduction angle detector 100 reads the amount of change in the effective value of the full-wave rectified voltage Vd (which can be considered as an input voltage to the power conversion circuit 1b).

  The change amount of the effective value correlates with the change amount of the conduction angle of the dimmer 2. Therefore, the conduction angle detection unit 100 outputs the detection signal S4 based on the obtained change amount of the effective value. Based on the detection signal S4, the control circuit K1 determines whether to operate in the normal operation mode or the low power mode, and controls the switching elements Q1a and Q1b. The control of the switching elements Q1a and Q1b by the control circuit K1 is the same as that in the above embodiment.

  The change amount of the peak value of the full-wave rectified voltage Vd is also correlated with the change amount of the conduction angle of the dimmer 2. Therefore, instead of reading the change amount of the effective value, the change amount of the peak value of the full-wave rectified voltage Vd may be read.

<< Modification 2 of Embodiment >>
FIG. 12 also shows a modification of the conduction angle detection unit 100. That is, in this example, the configuration of the conduction angle detection unit 100 is different from that of the embodiment.

  The conduction angle detection unit 100 is configured to read a voltage applied to a constant current circuit (FET element Q91, operational amplifier OP91). Specifically, as shown in FIG. 12, the conduction angle detecting unit 100 receives the voltage Vq and reads the value.

  Then, the conduction angle detection unit 100 compares the voltage Vq with a predetermined threshold Vth1 (see FIG. 10), and when the voltage Vq is equal to or higher than the threshold Vth1, the dimming speed of the dimmer 2 is predetermined. It is determined that the threshold value is exceeded, and is output as a detection signal S4. Then, the control circuit K1 switches to the operation in the low power mode based on the detection signal S4. The period during which the setting of the low supply power state is maintained is, for example, until the voltage Vq becomes equal to or lower than the threshold value Vth2 (see FIG. 10). As described above, by providing a difference between the threshold values Vth1 and Vth2 for switching between the normal operation mode and the low power mode, it is possible to suppress malfunction.

  Note that a period for maintaining the operation in the low power mode may be controlled by a timer.

<< Modification 3 of Embodiment >>
FIG. 13 also shows a modification of the conduction angle detection unit 100. That is, in this example, the configuration of the conduction angle detection unit 100 is different from that of the embodiment.

  The conduction angle detector 100 is configured to read the amount of decrease in the control voltage (the voltage VFB of the feedback signal S3) of the voltage feedback circuit (the operational amplifier OP92). Then, the conduction angle detection unit 100 determines that the dimming speed of the dimmer 2 has exceeded a predetermined threshold when the voltage VFB decreases and becomes equal to or lower than the predetermined threshold Vth3 (see FIG. 10). , And output as a detection signal S4. Then, the control circuit K1 switches to the operation in the low power mode based on the detection signal S4. The period in which the operation in the low power mode is maintained is until the voltage VFB is equal to or higher than the threshold value Vth4 (see FIG. 10). As described above, by providing a difference between the threshold values Vth3 and Vth4 for switching between the normal operation mode and the low power mode, it is possible to suppress malfunction.

  In this example as well, the period during which the operation in the low power mode is maintained may be controlled by a timer.

<< Modification 4 of Embodiment >>
Although specific illustration is omitted, power conversion is performed according to at least one of the dimming speed of the dimmer 2 or the current If flowing through the light source unit 1h at the start of change in the dimming speed of the dimmer. The power supply amount of the circuit 1b may be reduced. That is, you may make it change the reduction amount of the power supply of the power converter circuit 1b according to the speed of light control, or the electric current If of the light source part 1h.

  Furthermore, the threshold for determining the dimming speed of the dimmer may be changed according to the change speed of the dimming speed of the dimmer 2. For example, the threshold for determining that the dimming speed exceeds a predetermined threshold may be set higher as the change rate of the dimming speed of the dimmer 2 increases more rapidly.

  Further, in the control circuit 1K, it is preferable that the reduction amount of the power supply amount of the power conversion circuit 1b is further increased as the speed of change of the conduction angle (the dimming speed) is increased. By doing so, it is possible to reliably reduce the stress applied to the circuit elements constituting the lighting device.

<< Variation 5 of the embodiment >>
In general, in a lighting fixture including a lighting device, a protection circuit may be provided for the purpose of protecting circuit elements. For example, such a protection circuit (safety mechanism) may be configured to detect the voltage V02 and stop the circuit (for example, the power conversion circuit 1b) when the voltage V02 exceeds a predetermined threshold value Vth5. Conceivable. The threshold value Vth5 generally needs to be set with a predetermined margin from the viewpoint of reliably protecting the circuit.

  On the other hand, in the embodiment and each modification, when the speed of dimming exceeds a predetermined threshold, it functions as a safety mechanism by temporarily increasing the power consumption of the power conversion circuit. . Therefore, in the present embodiment, when the protection circuit is used in combination, the margin can be made smaller than before.

  That is, the threshold value Vth5 of the protection circuit can be made higher than that of the conventional lighting fixture. Thus, if the threshold value Vth5 of the protection circuit can be increased, the probability that the circuit is stopped is also reduced. That is, according to the present embodiment, user convenience is improved.

  Note that the voltage V02 as an index of operation in the protection circuit is an example. Even in the protection circuit based on other voltage detection values, the threshold value for defining the start of operation can be made higher by combining the embodiments.

DESCRIPTION OF SYMBOLS 1 Lighting fixture 1b Power conversion circuit 1h Light emitting element 90 RC circuit 100 Conduction angle detection part (control part)
OP91 operational amplifier (comparator)
OP92 Voltage feedback circuit Q91 FET element S2 Target signal S3 Control signal

Claims (6)

A power conversion circuit that receives power from a phase control dimmer and supplies power to the light emitting element;
A constant current circuit for passing a constant current through the light emitting element;
A voltage feedback circuit that outputs to the power conversion circuit a control signal for controlling the output voltage of the power conversion circuit to a predetermined target value;
And a controller that temporarily reduces the amount of power supplied to the power conversion circuit when the dimming speed of the dimmer exceeds a predetermined threshold value. In claim 1,
The control unit temporarily decreases the power supply amount of the power conversion circuit by causing the power conversion circuit to intermittently operate or temporarily stopping the operation of the power conversion circuit. . In claim 1,
The power conversion circuit includes a transformer that receives power supply from the dimmer in a primary winding and outputs output power from a secondary winding to the light emitting element.
The said control part reduces the power supply amount of the said power converter circuit temporarily by reducing the ratio of the secondary winding with respect to the primary winding of the said transformer. The lighting device characterized by the above-mentioned. In claim 1 or claim 2,
The control unit, based on the amount of change in any of the phase of the input voltage to the power conversion circuit, the effective value of the input voltage to the power conversion circuit, and the peak value of the input voltage to the power conversion circuit, Alternatively, it is determined whether or not the dimming speed exceeds the threshold based on any value of the control signal and the voltage of the constant current circuit. In any one of Claims 1-4,
The control unit, when the dimming speed of the dimmer exceeds a predetermined threshold, at the start of a change in the dimming speed of the dimmer or the dimming speed of the dimmer The lighting device, wherein the power supply amount of the power conversion circuit is reduced according to at least one of the currents flowing through the light emitting elements. A lighting device according to any one of claims 1 to 4,
And a light-emitting element.

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