JP5220233B2 - Power supply device and lighting fixture - Google Patents

Description

  The present invention relates to a power supply device that performs constant current operation by feedback control.

  In a power supply device that supplies power to a load circuit having a load that should be driven at a constant current, such as a light-emitting diode, the value of the load current flowing through the load is measured, and the measurement result is fed back to adjust the generated power Thus, there is a power supply device that operates as a constant current source.

JP 2007-234414 A JP 2005-142137 A JP 2004-319583 A Japanese Patent Laid-Open No. 7-20953 JP 2010-28951 A JP 2005-168169 A JP 2009-189158 A

The feedback control inevitably involves a control delay. The load current does not immediately reach the target value, but, for example, repeatedly overshoots / undershoots and gradually converges to the target value.
When the load is a light source such as a light emitting diode, it appears to emit a flash for a moment during overshoot. In addition, the load may fail due to an overcurrent generated by overshoot.
The present invention has been made, for example, in order to solve the above-described problems, and an object thereof is to prevent the occurrence of flashing or failure with a simple configuration.

The power supply device according to the present invention is
A DC power supply circuit that generates DC power to be supplied to the load circuit;
A load current detection circuit that detects a load current flowing through the load circuit and generates a load current detection voltage having a voltage value proportional to the current value of the detected load current;
A target voltage generation circuit that generates a target voltage based on a target value of a load current flowing through the load circuit;
A feedback signal generation circuit that compares the voltage value of the load current detection voltage generated by the load current detection circuit with the voltage value of the target voltage generated by the target voltage generation circuit and generates a feedback signal indicating which is greater; ,
A control power supply circuit that generates control power and supplies the generated control power to the DC power supply circuit and the target voltage generation circuit;
The DC power supply circuit receives the feedback signal generated by the feedback signal generation circuit, and based on the input feedback signal, when the load current detection voltage is larger than the target voltage, reduces the generated DC power, If the load current detection voltage is smaller than the target voltage, increase the generated DC power,
The DC power supply circuit operates with the control power supplied by the control power supply circuit,
The target voltage generation circuit generates the target voltage from the control power supplied by the control power supply circuit,
The control power supply circuit does not supply control power to the DC power supply circuit and the target voltage generation circuit when a target value of a load current flowing through the load circuit is 0.

  According to the power supply device of the present invention, the control power supply circuit supplies the control power to the DC power supply circuit and the target voltage generation circuit when the target value of the load current flowing through the load circuit is 0. Since it is not supplied, it is possible to reduce power consumption, particularly power consumption during standby (standby power).

FIG. 4 is a side cross-sectional view illustrating an example of the structure of the lighting fixture 800 according to Embodiment 1. FIG. 3 is a block configuration diagram illustrating an example of a functional block configuration of the power supply device 100 according to the first embodiment. FIG. 3 is a circuit diagram illustrating an example of a specific circuit configuration of the power supply device 100 according to the first embodiment. FIG. 3 is a waveform diagram illustrating an example of a waveform such as a voltage of each part of the power supply device 100 according to the first embodiment. The wave form diagram which shows an example of the waveform of the electric current in a comparative example. FIG. 4 is a waveform diagram showing an example of a current waveform of the power supply device 100 according to the first embodiment. FIG. 6 is a waveform diagram illustrating an example of a voltage waveform of each part of the power supply device 100 according to the second embodiment. FIG. 6 is a waveform diagram illustrating an example of a waveform such as a voltage of each part of the power supply device 100 according to the second embodiment. FIG. 9 is a waveform diagram showing another example of a waveform such as a voltage of each part of power supply device 100 according to the second embodiment. FIG. 12 is a waveform diagram showing still another example of a waveform such as a voltage of each part of power supply device 100 in the second embodiment. FIG. 6 is a circuit diagram showing an example of a specific circuit configuration of power supply device 100 according to Embodiment 3. FIG. 10 is a waveform diagram illustrating an example of a waveform such as a voltage of each part of the power supply device 100 according to the third embodiment.

Embodiment 1 FIG.
The first embodiment will be described with reference to FIGS.

FIG. 1 is a side sectional view showing an example of the structure of a lighting fixture 800 according to this embodiment.
The lighting fixture 800 includes a main body 810, a connector 821, a power supply line 822, a power supply device 100, a wiring 823, a light source substrate 831, and a light source 832.

The light source 832 is an electrical light source that is lit by DC power. The light source 832 is, for example, a light emitting diode element (hereinafter referred to as “LED”). The light source 832 is mounted on the light source substrate 831. The number of light sources 832 may be one or two or more. When there are two or more light sources 832, the light sources 832 are electrically connected to each other in series, for example.
The light source substrate 831 is attached to the light emitting surface side (lower side in this example) of the main body 810. The light source substrate 831 is provided with wiring for connecting the light sources 832 by printing or the like. Components other than the light source 832 may be mounted on the light source substrate 831. Hereinafter, a circuit including components mounted on the light source substrate 831 such as the light source 832 and wirings provided on the light source substrate 831 is referred to as a “light source circuit 830”.

The connector 821 is connected to an AC power source AC such as a commercial power source (for example, an effective value of 100 to 242 volts [V], a frequency of 50 to 60 hertz [Hz]). The connector 821 inputs AC power from the connected AC power source AC.
The power line 822 connects between the connector 821 and the power supply device 100. The power supply line 822 supplies the AC power input by the connector 821 to the power supply apparatus 100.

The power supply device 100 (LED lighting device) is housed inside the main body 810. The power supply device 100 converts the input AC power to generate DC power (load power) to be supplied to the light source circuit 830 (load circuit).
The wiring 823 connects between the power supply device 100 and the light source circuit 830. The wiring 823 supplies the DC power generated by the power supply device 100 to the light source circuit 830.

FIG. 2 is a block configuration diagram illustrating an example of a functional block configuration of the power supply device 100 according to the present embodiment.
The power supply device 100 includes a DC power supply circuit 110, a load current detection circuit 140, a target voltage generation circuit 170, and a feedback signal generation circuit 180.

  The DC power supply circuit 110 converts the power input from the AC power supply AC or other power supply to generate DC power to be supplied to the light source circuit 830. When the DC power generated by the DC power supply circuit 110 is supplied to the light source circuit 830, a DC current (load current) flows through the light source circuit 830.

  The load current detection circuit 140 detects the direct current flowing through the light source circuit 830 and generates a voltage having a voltage value proportional to the detected current value (hereinafter referred to as “load current detection voltage”).

  The target voltage generation circuit 170 inputs a signal indicating the target value of the direct current flowing through the light source circuit 830 (hereinafter referred to as “target instruction signal”). The target voltage generation circuit 170 generates a target voltage based on the target value indicated by the input target instruction signal. The target voltage is a reference voltage for determining whether the direct current flowing through the light source circuit 830 is larger or smaller than the target value by comparing with the load current detection voltage generated by the load current detection circuit 140. It is. In principle, the target voltage generation circuit 170 has a target voltage value equal to the voltage value of the load current detection voltage generated by the load current detection circuit 140 when the current value of the direct current flowing through the light source circuit 830 matches the target value. Generate voltage.

  The feedback signal generation circuit 180 compares the voltage value of the load current detection voltage generated by the load current detection circuit 140 with the voltage value of the target voltage generated by the target voltage generation circuit 170, and indicates a larger signal ( (Hereinafter referred to as “feedback signal”).

The DC power supply circuit 110 receives the feedback signal generated by the feedback signal generation circuit 180. The DC power supply circuit 110 adjusts the generated DC power based on the input feedback signal.
When the load current detection voltage is larger than the target voltage, the current value of the direct current flowing through the light source circuit 830 is larger than the target value, so the direct current power supply circuit 110 reduces the generated direct current power. As a result, the direct current flowing through the light source circuit 830 decreases and approaches the target value.
On the contrary, when the load current detection voltage is smaller than the target voltage, it means that the current value of the direct current flowing through the light source circuit 830 is smaller than the target value, so the DC power supply circuit 110 increases the generated DC power. . Thereby, the direct current flowing through the light source circuit 830 increases and approaches the target value.

  In the case where the light source 832 is an LED, the current flowing through the light source circuit 830 varies greatly due to a slight change in the voltage across the light source circuit 830. For this reason, when the DC power generated by the DC power supply circuit 110 is adjusted, only the DC current flowing through the light source circuit 830 changes, and the voltage across the light source circuit 830 seems to hardly change.

  The power supply apparatus 100 matches the current value of the direct current flowing through the light source circuit 830 with the target value by such feedback control. Thereby, the power supply apparatus 100 functions as a constant current source.

  When the target value indicated by the target instruction signal changes, a period in which the current value of the direct current flowing through the light source circuit 830 does not coincide with the target value temporarily occurs due to the characteristics of the feedback control.

In particular, when the target value becomes large, the target voltage generation circuit 170 does not increase the target voltage immediately after following the target value in order to prevent an overcurrent from flowing due to overshoot. Until the time elapses, a target voltage having a voltage value lower than a value corresponding to the target value is generated, and thereafter, a target voltage having a voltage value corresponding to the target value is generated. For example, the target voltage generation circuit 170 gradually increases the target voltage so that the increase rate of the voltage value of the target voltage does not exceed a predetermined increase rate. The increase rate is the amount of change per unit time. The rate of increase may be referred to as time differentiation or the slope of a graph with time on the horizontal axis. As a result, the target voltage slowly increases with a delay from the change in the target value.
In addition, when the target value becomes large, the case where the lighting fixture 800 is turned off by turning off the power supply of the lighting fixture 800 or the like is changed to the lighting state by turning on the lighting fixture 800 or the like.

FIG. 3 is a circuit diagram showing an example of a specific circuit configuration of the power supply device 100 according to this embodiment.
The power supply device 100 further includes a dimming signal input circuit 150, a dimming signal input unit 250, and a control power circuit 160 in addition to the above-described configuration. Further, the power supply apparatus 100 includes a microcomputer 200.

The microcomputer 200 includes a processing device, a storage device, an input device, and an output device that are not shown.
The processing device processes data by executing a program stored in the storage device, and controls the entire microcomputer 200.
The storage device stores a program executed by the processing device and data processed by the processing device.
The input device inputs an analog signal or a digital signal from the outside of the microcomputer 200, and converts the input signal into data in a format that can be processed by the processing device. The data converted by the input device may be processed directly by the processing device or stored by the storage device.
The output device converts the data processed by the processing device or the data stored in the storage device into an analog signal or a digital signal, and outputs the converted signal to the outside of the microcomputer 200.
The microcomputer 200 operates with the control power supply power generated by the control power supply circuit 160. The microcomputer 200 implements functional blocks such as a dimming signal input unit 250, a power signal signal generation unit 260, and a rectangular wave signal generation unit 270 described below when the processing device executes a program stored in the storage device.

  Note that the functional blocks such as the dimming signal input unit 250, the power supply signal generation unit 260, and the rectangular wave signal generation unit 270 are not microcomputers 200, but electronic units such as analog circuits and digital circuits configured by electronic elements and integrated circuits. A configuration realized by a circuit or a configuration realized by a configuration other than an electrical configuration such as a mechanical configuration may be used.

  The DC power supply circuit 110 includes a rectifier circuit 111, a power factor correction circuit 112, a control IC 117, a smoothing capacitor C24, a step-down circuit 113, a control IC 118, and a smoothing capacitor C34.

  The rectifier circuit 111 rectifies the AC power input from the AC power supply AC and makes the voltage waveform pulsate. The rectifier circuit 111 includes, for example, a diode bridge DB1. The diode bridge DB1 is a circuit in which four diodes are bridge-connected. The diode bridge DB1 performs full-wave rectification on the input AC power.

The power factor correction circuit 112 makes the current waveform of AC power input by the power supply apparatus 100 close to a voltage waveform, and brings the power factor of the power supply apparatus 100 close to 1. The power factor correction circuit 112 includes, for example, a boost chopper circuit that includes a choke coil L21 (first inductor), a switching element Q22, and a diode D23.
The control IC 117 generates a control signal for turning on / off the switching element Q22 at a high frequency. The control IC 117 detects the input voltage, output voltage, input current, and the like of the power factor correction circuit 112 by a detection circuit (not shown), and turns on / off the switching element Q22 so that the power factor of the power supply apparatus 100 approaches 1. Adjust. Further, the control IC 117 adjusts the timing at which the switching element Q22 is turned on / off so that the output voltage of the power factor correction circuit 112 becomes a predetermined voltage value (for example, 400V). The control IC 117 operates with power supplied from the control power supply generation circuit 161 (hereinafter referred to as “control power supply power”).
The smoothing capacitor C24 smoothes the output voltage of the power factor correction circuit 112 to a DC voltage having a substantially constant voltage value.
The power factor correction circuit 112 may not be provided. In that case, the smoothing capacitor C24 smoothes the pulsating flow rectified by the rectifier circuit 111, and generates a DC voltage having a substantially constant voltage value.

The step-down circuit 113 (DC / DC conversion circuit) steps down the output voltage of the power factor correction circuit 112 to a voltage value to be applied to the light source circuit 830. The step-down circuit 113 includes, for example, a step-down chopper circuit that includes a switching element Q31, a drive circuit 114, a freewheeling diode D32, and a choke coil L33 (second inductor).
The control IC 118 generates a control signal (gate signal) for turning on / off the switching element Q31 at a high frequency. The drive circuit 114 shifts the voltage of the control signal generated by the control IC 118 and converts it into a drive signal for driving the switching element Q31. The drive circuit 114 is configured using, for example, a pulse transformer or a photocoupler. The control IC 118 adjusts the DC power generated by the DC power supply circuit 110 by adjusting the timing for turning on and off the switching element Q31 based on the feedback signal generated by the feedback signal generation circuit 180. If the ratio (ON duty) of the period during which the switching element Q31 is ON is large, the DC power generated by the DC power supply circuit 110 is increased. Conversely, if the ratio of the period during which the switching element Q31 is on is small, the DC power generated by the DC power supply circuit 110 is small. The control IC 118 operates with the control power supply supplied from the control power generation circuit 161.
Note that the step-down circuit 113 may be another DC-DC conversion circuit such as a flyback converter.
The smoothing capacitor C34 smoothes the output voltage of the step-down circuit 113 to a DC voltage having a substantially constant voltage value.

The load current detection circuit 140 includes a current detection resistor R41, a resistor R42, and a capacitor C43.
The current detection resistor R41 is inserted in a path through which a current for charging the smoothing capacitor C34 flows in the DC power supply circuit 110. A voltage having a voltage value proportional to the current value of the current that charges the smoothing capacitor C34 is generated at both ends of the current detection resistor R41.
The current detected by the current detection resistor R41 varies with time. The current value of the direct current flowing through the light source circuit 830 is the average value of the current detected by the current detection resistor R41.
The resistor R42 and the capacitor C43 constitute an integrating circuit. The integrating circuit composed of the resistor R42 and the capacitor C43 removes the high frequency component of the voltage generated at both ends of the current detection resistor R41, and extracts the low frequency component and the DC component.
The load current detection circuit 140 outputs the voltage extracted by the integration circuit constituted by the resistor R42 and the capacitor C43 as a load current detection voltage. As a result, the voltage value of the load current detection voltage becomes an average value of the voltages generated at both ends of the current detection resistor R41. Therefore, the voltage value of the load current detection voltage is proportional to the current value of the direct current flowing through the light source circuit 830. To do.

The dimming signal input circuit 150 inputs a dimming signal from the outside. The dimming signal is an example of a target instruction signal. For example, the dimming controller 850 generates the dimming signal. The dimming controller 850 inputs the dimming rate desired by the user using, for example, a volume or a remote controller. The dimming controller 850 generates a dimming signal according to the input dimming rate. The dimming signal is, for example, a pulse width modulated signal (hereinafter referred to as “PWM signal”). The dimming signal represents, for example, a turn-off instruction when the on-duty is 100%, and a turn-on instruction at a bright dimming rate as the on-duty is within a predetermined range. The dimming signal may be transmitted by a dedicated signal line that connects between the dimming controller 850 and the dimming signal input circuit 150, or via another signal line (for example, the power supply line 822). May be transmitted. Alternatively, the dimming signal may be transmitted by wireless communication using infrared rays or radio waves instead of wired connection.
The dimming signal input circuit 150 includes, for example, a photocoupler PC1 and a pull-up resistor R51. The photocoupler PC1 transmits the dimming signal input from the dimming controller 850 to the dimming signal input unit 250 while being electrically insulated. The photocoupler PC1 includes an optically coupled LED and a phototransistor. When the LED is turned on, the phototransistor is turned on, and the potential of the signal output from the dimming signal input circuit 150 becomes low. When the LED is turned off, the phototransistor is turned off, and the potential of the signal output from the dimming signal input circuit 150 becomes high. The dimming signal input circuit 150 outputs a signal whose polarity is inverted with respect to the input dimming signal.

The dimming signal input unit 250 converts the dimming signal input by the dimming signal input circuit 150 into data that can be processed by the processing device (hereinafter referred to as “dimming data”).
The dimming signal input unit 250 inputs the dimming signal transmitted from the dimming signal input circuit 150 when the processing device controls the input device. The dimming signal input unit 250 calculates the dimming rate represented by the input dimming signal when the processing device processes the data. The dimming signal input unit 250 generates dimming data representing the calculated dimming rate when the processing device processes the data. The dimming signal input unit 250 stores the generated dimming data in the storage device by the processing device controlling the storage device.

  The control power supply circuit 160 includes a control power supply generation circuit 161, a power supply signal generation unit 260, a switching circuit 162, and a step-down circuit 163.

  For example, the control power generation circuit 161 converts part of the DC power output from the power factor correction circuit 112 to generate control power for operating the control ICs 117 and 118 and the like. For example, the control power supply generation circuit 161 steps down the DC voltage charged in the smoothing capacitor C24 to a DC voltage (for example, 15V) that operates the control ICs 117 and 118 and the like. The control power supply generation circuit 161 outputs control power supply having a stepped down voltage value. The control power supply generation circuit 161 is, for example, a step-down chopper circuit. Alternatively, the control power generation circuit 161 may be a constant voltage source circuit using a constant voltage diode such as a Zener diode or a three-terminal regulator.

The step-down circuit 163 converts part of the control power supply generated by the control power supply generation circuit 161 and generates microcomputer control power supply for operating the microcomputer 200. The step-down circuit 163 further steps down the direct current voltage (for example, 15V) of the control power supply generated by the control power generation circuit 161 to obtain the direct current voltage (for example, 5V) that causes the microcomputer 200 to operate. The step-down circuit 163 is a constant voltage source circuit using a constant voltage diode such as a Zener diode or a three-terminal regulator, for example.
When the power supply voltage of the microcomputer 200 is equal to the power supply voltage of the control ICs 117 and 118, the step-down circuit 163 is eliminated and the microcomputer 200 directly inputs the control power supply power output from the control power supply generation circuit 161 as a power supply. It may be.

The power signal generation unit 260 (power signal generation circuit) generates a power signal. The power supply signal indicates whether or not the control power supply generated by the control power supply generation circuit 161 is supplied to the control ICs 117 and 118. When the dimming signal input from dimming signal input circuit 150 indicates extinction, power supply signal generation unit 260 generates a power supply signal indicating that control power is not supplied. When the dimming signal indicates lighting at some dimming rate, the power supply signal generation unit 260 generates a power supply signal indicating supply of control power. For example, the power supply signal indicates that the control power supply is supplied when the potential is high, and the control power supply is not supplied when the potential is low.
The power signal generation unit 260 reads the dimming data generated by the dimming signal input unit 250 from the storage device when the processing device processes the storage device. The power supply signal generation unit 260 determines whether or not the read dimming data indicates light extinction when the processing device processes the data. Based on the determination result, the power supply signal generation unit 260 controls the output device to generate a power supply signal, and outputs the generated power supply signal.

The switching circuit 162 is interposed between the control power supply generation circuit 161 and the control ICs 117 and 118. The switching circuit 162 inputs the power supply signal generated by the power supply signal generation unit 260. The switching circuit 162 connects or disconnects between the control power generation circuit 161 and the control ICs 117 and 118 based on the input power signal. When the switching circuit 162 connects between the control power supply generation circuit 161 and the control ICs 117 and 118, the control power supply generated by the control power supply generation circuit 161 is supplied to the control ICs 117 and 118. Conversely, when the switching circuit 162 disconnects between the control power supply generation circuit 161 and the control ICs 117 and 118, the control power supply power is not supplied to the control ICs 117 and 118.
The switching circuit 162 includes, for example, a switching element Q61, a resistor R62, a resistor R63, and a switching element Q64. The switching element Q61 is, for example, an NPN bipolar transistor. The switching element Q61 receives the power signal generated by the power signal generation unit 260. The switching element Q61 is turned on when the input power supply signal is at a high potential, and turned off when the power supply signal is at a low potential. The switching element Q64 is, for example, an enhancement type pMOS field effect transistor. When the switching element Q61 is on, a current flows through the resistor R62 and the resistor R63, a voltage is generated across the resistor R63, and the switching element Q64 is turned on. When the switching element Q61 is off, no current flows through the resistor R62 and the resistor R63, and the voltage across the resistor R63 becomes 0, so that the switching element Q64 is turned off. When the switching element Q64 is turned on, the control power generation circuit 161 and the control ICs 117 and 118 are connected to supply control power to the control ICs 117 and 118. When the switching element Q64 is turned off, the control power generation circuit 161 and the control ICs 117 and 118 are disconnected, and the control power is not supplied to the control ICs 117 and 118.

  The target voltage generation circuit 170 includes a rectangular wave voltage generation circuit 171 and an integration circuit 172.

  The rectangular wave voltage generation circuit 171 generates a rectangular wave voltage having a duty ratio corresponding to the dimming rate indicated by the dimming signal input by the dimming signal input circuit 150. The rectangular wave voltage generated by the rectangular wave voltage generation circuit 171 has a ratio of the length of a period during which the rectangular wave voltage is at a high potential to the length of one period of the rectangular wave voltage (for example, 5 to 20 microseconds). , Corresponding to the dimming rate. The rectangular wave voltage generation circuit 171 includes, for example, a rectangular wave signal generation unit 270, a switching element Q71, and a resistor R72.

The rectangular wave signal generation unit 270 (rectangular wave signal generation circuit) generates a rectangular wave signal having a duty ratio corresponding to the dimming rate represented by the dimming signal input by the dimming signal input circuit 150. The rectangular wave signal generated by the rectangular wave signal generation unit 270 has a polarity opposite to that of the rectangular wave voltage. That is, in the rectangular wave signal, the ratio of the length of the period during which the rectangular wave signal is at a low potential to the length of one period of the rectangular wave signal corresponds to the dimming rate.
The rectangular wave signal generation unit 270 reads the dimming data generated by the dimming signal input unit 250 from the storage device when the processing device controls the storage device. The rectangular wave signal generation unit 270 generates and outputs a rectangular wave signal having a duty ratio corresponding to the dimming rate represented by the read dimming data when the processing device controls the output device.

The switching element Q71 is, for example, an NPN bipolar transistor. Switching element Q71 has an emitter terminal connected to a ground wiring in power supply device 100. The switching element Q71 has a base terminal connected to the output of the rectangular wave signal generation unit 270. The switching element Q71 inputs the rectangular wave signal output from the rectangular wave signal generation unit 270. The switching element Q71 is turned on when the input rectangular wave signal has a high potential, and turned off when the rectangular wave signal has a low potential.
One terminal of the resistor R72 is connected to the control power generation circuit 161 via the switching circuit 162. The other terminal is connected to the collector terminal of switching element Q71.
The rectangular wave voltage generation circuit 171 outputs a voltage generated between the collector and emitter of the switching element Q71 as a rectangular wave voltage. When the switching element Q71 is on, the rectangular wave voltage generated by the rectangular wave voltage generation circuit 171 becomes a low potential. When the switching element Q71 is off and the switching circuit 162 is on, the rectangular wave voltage generated by the rectangular wave voltage generation circuit 171 becomes a high potential. Even if the switching element Q71 is off, if the switching circuit 162 is off, the rectangular wave voltage generated by the rectangular wave voltage generation circuit 171 becomes a low potential.
Therefore, the rectangular wave voltage generation circuit 171 generates a rectangular wave voltage having a polarity opposite to that of the rectangular wave signal generated by the rectangular wave signal generation unit 270 when the switching circuit 162 is on, and when the switching circuit 162 is off, Does not generate square wave voltage.

The integration circuit 172 integrates the rectangular wave voltage generated by the rectangular wave voltage generation circuit 171 to generate a target voltage. The integration circuit 172 removes the high frequency component of the rectangular wave voltage generated by the rectangular wave voltage generation circuit 171 and extracts the low frequency component and the direct current component. Thereby, the integration circuit 172 generates a target voltage having an average value of instantaneous values of the rectangular wave voltage as a voltage value.
The integration circuit 172 includes, for example, a resistor R73 and a capacitor C74. When the switching element Q71 is on, a current for discharging the capacitor C74 flows through the resistor R73. When the switching element Q71 is off, a current for charging the capacitor C74 flows through the two resistors R72 and R73. The integration circuit 172 outputs the voltage generated at both ends of the capacitor C74 as a target voltage.

  The feedback signal generation circuit 180 includes an error amplifier A81. The error amplifier A81 is, for example, an operational amplifier. The error amplifier A81 amplifies the difference between the load current detection voltage generated by the load current detection circuit 140 and the target voltage generated by the target voltage generation circuit 170 and uses it as a feedback signal.

FIG. 4 is a waveform diagram showing an example of a waveform such as a voltage of each part of the power supply device 100 according to this embodiment.
The horizontal axis indicates time. The vertical axis indicates the dimming rate, duty ratio, voltage value, and current value.
A solid line 501 indicates the dimming rate indicated by the dimming signal input by the power supply apparatus 100. A solid line 502 indicates the duty ratio of the rectangular wave signal generated by the rectangular wave signal generation unit 270. A solid line 503 indicates the voltage value of the target voltage generated by the integration circuit 172. A solid line 505 indicates a current value of a direct current flowing through the light source circuit 830.
A broken line 511 indicates a dimming rate of 100%. A broken line 512 indicates the duty ratio of the rectangular wave signal corresponding to the dimming rate of 100%. A broken line 513 indicates a voltage value of the target voltage corresponding to the dimming rate of 100%. A broken line 514 indicates the upper limit of the increase rate of the target voltage. A broken line 515 indicates the current value of the direct current flowing through the light source circuit 830 when the load current detection voltage generated by the load current detection circuit 140 matches the target voltage generated by the integration circuit 172.

In before time t _1, the dimming signal, instructs the dimming ratio 0% (OFF). In accordance with this, the rectangular wave signal generation unit 270 generates a rectangular wave signal with a duty ratio of 0%. Since the rectangular wave signal generated by the rectangular wave signal generation unit 270 is negative logic, the rectangular wave signal generation unit 270 generates a signal that maintains a high potential as a rectangular wave signal with a duty ratio of 0%. Since the switching element Q71 is continuously turned on, the capacitor C74 is not charged and the voltage across the capacitor C74 becomes zero. That is, the integration circuit 172 generates a target voltage having a voltage value of zero. As a result, no current flows through the light source circuit 830, and the light source 832 is turned off.

Between the time t ₁ to time t _2, the dimming signal, instructs the lighting at the dimming ratio of 100%. The rectangular wave signal generation unit 270 generates a rectangular wave signal having a duty ratio (for example, 100%) corresponding to a dimming rate of 100%.
While the rectangular wave signal is at a low potential, the switching element Q71 is turned off, and the capacitor C74 is charged through the resistor R72 and the resistor R73 by the control power supply power generated by the control power supply generation circuit 161. When the rectangular wave signal becomes a high potential, the switching element Q71 is turned on, and the capacitor C74 is discharged via the resistor R73 and the switching element Q71.

スイッチング素子Ｑ７１がオンのとき、

ただし、ｔは時刻、ｖ_Ｃ（０）はｔ＝０のときのコンデンサＣ７４の両端電圧、ｅｘｐは自然対数の底（ネイピア数）を底とする指数関数を示す。 The voltage value of the control power supply generated by the control power supply generation circuit 161 is V _CC , the resistance value of the resistor R72 is R ₁ , the resistance value of the resistor R73 is R ₂ , the capacitance of the capacitor C74 is C, and the voltage across the capacitor C74 is Is v _C , when the switching element Q71 is off,

When switching element Q71 is on,

Where t is time, v _C (0) is the voltage across capacitor C74 when t = 0, and exp is an exponential function with the base of the natural logarithm (Napier number) as the base.

積分回路１７２は、この式に示した値を超えない増加率で、目標電圧の電圧値を増加させる。時刻ｔ_３において、積分回路１７２が生成する目標電圧の電圧値は、調光率１００％に対応する値に達する。 Therefore, the increase rate of the voltage v _C across the capacitor C74 is maximized when the switching element Q71 is off, t = 0, and v _C = 0.

The integration circuit 172 increases the voltage value of the target voltage at an increase rate not exceeding the value shown in this equation. At time t _3, the voltage value of the target voltage generated by the integrator circuit 172 reaches a value corresponding to the dimming ratio of 100%.

If there is no delay associated with the feedback control, the solid line 505 indicating the current value of the direct current flowing through the light source circuit 830 coincides with the broken line 515. However, in reality, since there is a delay associated with the feedback control, the current value of the direct current flowing through the light source circuit 830 changes later than the change in the target voltage. Although depending on the transfer characteristics of the feedback loop, the current value of the direct current flowing through the light source circuit 830 is, for example, overshoot (time t ₄ , t ₆ , t ₈ ,...), Undershoot (time t ₅ , t ₇ ,. ), And converges to a value corresponding to the voltage value of the target voltage.

At time t _4, which is the peak of the first overshoot voltage value of the target voltage is a target voltage generating circuit 170 generates does not reach the value corresponding to the dimming ratio of 100%. Therefore, the current value of the direct current flowing through the light source circuit 830 is larger than the value corresponding to the target voltage, but is smaller than the current value of the direct current that should flow through the light source circuit 830 when the dimming rate is 100%.
Thereafter, the overshoot / undershoot amplitude gradually decreases. For this reason, the current flowing through the light source circuit 830 at the time of peak overshoot (time t ₄ , t ₆ , t ₈ ,...) Does not greatly exceed the current that should flow through the light source circuit 830 when the dimming rate is 100%. .
Then, the time of time t ₃ when the voltage value of the target voltage reaches a value corresponding to 100% dimming rate, almost no overshoot, undershoot, the light source circuit 830, when the dimming ratio of 100% A current having a current value to flow flows.
Therefore, it is possible to prevent the flashing phenomenon that the light source 832 shines brightly for a moment and the occurrence of a failure due to overcurrent.

積分回路１７２は、この式に示した値を超えない減少率で、調光率０％に対応する値（０）に達するまで、目標電圧の電圧値を減少させる。 In later than time t _2, the dimming signal is indicated again dimming rate 0% (OFF). In accordance with this, the rectangular wave signal generation unit 270 generates a rectangular wave signal with a duty ratio of 0%. Switching element Q71 is continuously turned on, and capacitor C74 is discharged.
The decrease rate of the voltage across the capacitor C74 (inverted sign) is maximum when t = 0 and v _C = V _CC , and the value is

The integration circuit 172 decreases the voltage value of the target voltage until the value (0) corresponding to the dimming rate of 0% is reached at a reduction rate not exceeding the value shown in this equation.

  Compared with Equation 13, the maximum value of the decrease rate of the target voltage generated by the integration circuit 172 is larger than the maximum value of the increase rate. This means that the amplitude of the undershoot / overshoot generated when the dimming rate is lowered in the direct current flowing through the light source circuit 830 becomes larger than when the dimming rate is raised. However, since the voltage value of the DC power generated by the DC power supply circuit 110 never falls below 0, the current value of the DC current flowing through the light source circuit 830 never falls below 0 (that is, current flows in the reverse direction). .

FIG. 5 is a waveform diagram showing an example of a current waveform in the comparative example.
For comparison, at time t _1, the case where voltage value of the target voltage is a target voltage generating circuit 170 generates is to follow immediately the change in the dimming ratio, was changed to a value corresponding to the dimming ratio of 100% Show.
A solid line 506 indicates a current value of a direct current flowing through the light source circuit 830 in the comparative example. A broken line 516 indicates a current value of a direct current that should flow through the light source circuit 830 when the dimming rate is 100%.

  As shown in this figure, when the voltage value of the target voltage generated by the target voltage generation circuit 170 changes immediately following the change in the dimming rate, the amplitude of the overshoot / undershoot accompanying the delay in the feedback control becomes very large. Can be large. For this reason, at the peak of overshoot, there is a possibility that a flashing phenomenon that the light source 832 lights up very brightly or a failure such as destruction of the light source 832 due to overcurrent may occur.

  In contrast, the power supply apparatus 100 according to this embodiment can reduce the peak of the overshoot because the target voltage generation circuit 170 increases the voltage value of the target voltage at an increase rate lower than a predetermined increase rate. , Can prevent flashing and failure.

Further, if the maximum value of the increase rate of the target voltage is reduced and the time taken for the voltage value of the target voltage to reach a value corresponding to the dimming rate is extended (for example, to several seconds), the fade-in to the lighting apparatus 800 is performed. The effect of can be provided. Specifically, for example, if the resistance value R _{1 of} the resistor R 72, the resistance value R ₂ of the resistor R 73, or the capacitance C of the capacitor C 74 is increased, the maximum value of the increase rate shown in Equation 13 is decreased.

Further, as with the maximum value of the increase rate, the effect of fading out can be imparted to the lighting fixture 800 by reducing the maximum value of the decrease rate of the target voltage. Specifically, for example, if a very large resistance value R ₂ of the resistor R73 as compared to the resistance value R ₁ of the resistor R72, the maximum value of the reduction rate of the target voltage, the maximum value of the increase rate of the target voltage Is almost the same.

FIG. 6 is a waveform diagram showing an example of a current waveform of power supply device 100 in this embodiment.
The horizontal axis indicates time. The vertical axis represents the current value.
As in FIG. 4, the solid line 505 indicates the current value of the direct current flowing through the light source circuit 830. A broken line 515 indicates the current value of the direct current flowing through the light source circuit 830 when the load current detection voltage generated by the load current detection circuit 140 matches the target voltage generated by the integration circuit 172.

This figure shows a case where the maximum value of the target voltage increase rate and the maximum value of the target voltage decrease rate are reduced.
Thus, by reducing the maximum value of the target voltage increase rate and the maximum value of the target voltage decrease rate, the overshoot / undershoot amplitude is reduced. Further, at the time of lighting, a fade-in effect is produced in which the light source 832 is gradually brightened and turned on. Further, when the light is turned off, the light source 832 gradually becomes darker, and a fade-out effect that turns off the light is produced.

Fade-in and fade-out when the LED is turned on or off may be controlled by a microcomputer. In this case, the amount of change in fade-in (or fade-out) is made constant, and the brightness changes almost linearly as time passes.
Note that, as a visual characteristic of the viewer, when the amount of change is changed to a constant value, the brightness feels abruptly changing at low illuminance. Therefore, for example, when the brightness is changed at a dimming rate lower than 40%, the amount of change may be more gradual than the amount of change in brightness at a high dimming rate of 40% or higher. Further, in order for the viewer to visually feel that the brightness is constantly changing, the brightness change characteristic may be a curve (n-order function: n is an even number).

  The power supply apparatus 100 supplies power for generating a target voltage (target signal value) for setting a target value of a current supplied to the light source 832 from the control power supply generation circuit 161 via the switching circuit 162. At the same time, power is supplied to the control ICs 117 and 118 that control the operation of the DC power supply circuit 110 via the same switching circuit 162. Therefore, when the switching circuit 162 is turned on, power is supplied to the control ICs 117 and 118 and a target voltage is generated. At this time, since the target voltage is supplied via a time constant circuit (integration circuit 172) composed of a resistor and a capacitor, the voltage value of the target voltage gradually increases immediately after the switching circuit 162 is turned on. Thereby, the target current value at the start of LED lighting can be kept low. Therefore, the overshoot current can be kept low with a simple circuit configuration, and the occurrence of flashing when the power is turned on and the maximum rated current over the LED can be suppressed.

  As described above, the power supply for generating the target voltage supplied to the error amplifier A81 is shared with the control ICs 117 and 118, and the switching circuit 162 is controlled to be turned on / off. Thereby, the lighting of the light source 832 (LED) is started only by the control of the switching circuit 162, and at the same time, the voltage value of the target voltage input to the non-inverting input terminal of the error amplifier A81 is suppressed to a low level at the start of lighting. Can do. Thereby, the target value of load current (LED current) can be set small at the start of lighting. Therefore, it is possible to suppress overshoot of the load current that occurs due to a delay in the response speed of the feedback system immediately after lighting. Further, the flash of the light source 832 and the maximum rated current of the light source 832 can be prevented from being exceeded. In addition, since the circuit configuration is simple, the power supply device 100 can be reduced in size and weight, and manufacturing costs, transportation costs, and the like can be reduced. Further, when a signal that instructs to turn off is output from the dimming controller 850, the switching circuit 162 blocks power supply to the control ICs 117 and 118 and the collector terminal of the switching element Q71 (transistor). Thereby, power consumption, especially power consumption during standby (standby power) can be reduced.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIGS.
In addition, about the part which is common in Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The structure of the lighting fixture 800, the functional block configuration, and the specific circuit configuration of the power supply device 100 in this embodiment are the same as those described in the first embodiment, and thus description thereof is omitted here.

  The rectangular wave signal generation unit 270 (rectangular wave signal generation circuit), in principle, corresponds to the dimming rate indicated by the dimming signal input by the dimming signal input circuit 150 when the processing device controls the output device. A rectangular wave signal having a duty ratio is generated. However, when the dimming rate indicated by the dimming signal becomes high, the rectangular wave signal generation unit 270 does not immediately increase the duty ratio following the target value, but the increase rate of the duty ratio is a predetermined value. The duty ratio is gradually increased so as not to exceed the increase rate.

FIG. 7 is a waveform diagram showing an example of the voltage waveform of each part of the power supply device 100 according to this embodiment.
The horizontal axis indicates time. The vertical axis represents voltage. A solid line 507 indicates the potential of the rectangular wave signal generated by the rectangular wave signal generation unit 270. A broken line 517 indicates a potential when the rectangular wave signal is at a high potential. A solid line 503 indicates the voltage value of the target voltage generated by the integration circuit 172. A broken line 518 indicates an average voltage value of the target voltage generated by the integration circuit 172.

The period T of the rectangular wave signal generated by the rectangular wave signal generation unit 270 is, for example, about 5 microseconds to 20 microseconds. Among these, if the length of the period during which the potential of the rectangular wave signal is low is t _ON , the duty ratio of the rectangular wave signal is represented by t _ON / T.
In the period in which the potential of the rectangular wave signal is low, the switching element Q71 is turned off, the capacitor C74 is charged, and the voltage value of the target voltage increases. Further, during the period when the potential of the rectangular wave signal is high, the switching element Q71 is turned on, the capacitor C74 is discharged, and the voltage value of the target voltage decreases.
When viewed in a time unit (for example, 1 millisecond or more) much larger than the period T of the rectangular wave signal, the voltage value of the target voltage generated by the integration circuit 172 may be considered to coincide with the broken line 518. Therefore, the slope of the broken line 518 is regarded as the target voltage increase rate.

FIG. 8 is a waveform diagram showing an example of a waveform such as a voltage of each part of the power supply device 100 according to this embodiment.
The horizontal axis indicates time. The vertical axis indicates the dimming rate, duty ratio, voltage value, and current value.
A solid line 501 indicates the dimming rate indicated by the dimming signal input by the power supply apparatus 100. A solid line 502 indicates the duty ratio of the rectangular wave signal generated by the rectangular wave signal generation unit 270. A solid line 503 indicates the voltage value of the target voltage generated by the integration circuit 172. A solid line 505 indicates a current value of a direct current flowing through the light source circuit 830.
A broken line 511 indicates a dimming rate of 100%. A broken line 512 indicates the duty ratio of the rectangular wave voltage corresponding to the dimming rate of 100%. A broken line 519 indicates an upper limit of the increasing rate of the duty ratio. A broken line 513 indicates a voltage value of the target voltage corresponding to the dimming rate of 100%. A broken line 514 indicates the upper limit of the target voltage increase rate (the slope of the broken line 518 in FIG. 7). A broken line 515 indicates the current value of the direct current flowing through the light source circuit 830 when the load current detection voltage generated by the load current detection circuit 140 matches the target voltage generated by the integration circuit 172.

In before time t _1, the dimming signal, instructs the dimming ratio 0% (OFF).
In the period from time t ₁ to time t _2, the dimming signal, it instructs the lighting at the dimming ratio of 100%. The rectangular wave signal generation unit 270 slowly increases the duty ratio of the generated rectangular wave signal at an increase rate lower than the increase rate indicated by the broken line 519 until a duty ratio corresponding to the dimming rate of 100% is reached.

この一周期におけるコンデンサＣ７４の両端電圧の平均増加率は、ｔ＝ＴにおけるコンデンサＣ７４の両端電圧ｖ_Ｃ（Ｔ）と、ｔ＝０におけるコンデンサＣ７４の両端電圧ｖ_Ｃ（０）との差を、周期Ｔで割ることにより、求められる。

だから、

The time when the rectangular wave signal changes from high potential to low potential is t = 0, the time when the rectangular wave signal changes from low potential to high potential is t = t _ON , and the time when the rectangular wave signal changes again from high potential to low potential is t = T, the voltage v _C (t) across the capacitor C74 is

The average increase rate of the voltage across the capacitor C74 in one cycle is the difference between the voltage v _C (T) across the capacitor C74 at t = T and the voltage v _C (0) across the capacitor C74 at t = 0. It is obtained by dividing by the period T.

So,

The average increase rate of the voltage across the capacitor C74 increases as v _C (0) decreases, and increases as t _ON increases.
The rectangular wave signal generation unit 270 reduces the duty ratio of the generated rectangular wave signal and decreases t _ON in a period in which v _C (0) immediately after the dimming rate increases is small. Thereafter, as v _C (0) increases, the rectangular wave signal generation unit 270 increases the duty ratio of the rectangular wave signal to increase t _ON . As a result, the increase rate of the voltage value of the target voltage generated by the integration circuit 172 is suppressed to a predetermined increase rate or less indicated by the broken line 514.
Then, at time t _3, the voltage value of the target voltage generated by the integrator circuit 172 reaches a value corresponding to the dimming ratio of 100%.

  As a result, it is possible to reduce the peak of the overshoot caused by the delay associated with the feedback control, and to prevent the occurrence of flashing phenomenon or failure.

In the first embodiment, the increase rate / decrease rate of the target voltage is determined by the resistance value R _{1 of} the resistor R 72, the resistance value R ₂ of the resistor R 73, and the capacitance C of the capacitor C 74, whereas in this embodiment, By changing the increasing rate / decreasing rate of the duty ratio of the rectangular wave signal, the increasing rate / decreasing rate of the target voltage can be changed, and the increasing rate determined by the resistance value R ₁ , the resistance value R ₂ , and the capacitance C -It can be made smaller than the rate of decrease.

Accordingly, the resistance value R _1, the resistance value R _2, the increase rate determined by the capacitance C · reduction rate, so that a large value, the resistance value R _1, the resistance value R _2, by setting the electrostatic capacitance C The rectangular wave signal generation unit 270 changes the increase rate / decrease rate of the target voltage by changing the increase rate / decrease rate of the duty ratio of the rectangular wave signal as necessary.
For example, when the dimming rate indicated by the dimming signal changes from 0% to 100%, the peak of the overshoot may be the largest. For this reason, the rectangular wave signal generation unit 270 reduces the increase rate of the duty ratio of the rectangular wave signal and decreases the increase rate of the target voltage.
On the other hand, for example, when the dimming rate indicated by the dimming signal is changed from 40% to 50% or the like, when the increase width of the dimming rate is small, the peak of the overshoot is not so large. Further, when the dimming rate after the change is low, the target value of the current that should be passed through the light source circuit 830 is small in the first place, so that even if an overshoot occurs, an overcurrent that causes a failure does not flow. For this reason, the rectangular wave signal generation unit 270 increases the increasing rate of the duty ratio of the rectangular wave signal to set the increasing rate of the target voltage to a relatively large value. Thereby, the time taken for the dimming rate of the lighting fixture 800 to be the dimming rate indicated by the user can be shortened.
In addition, when receiving an instruction to generate a special lighting effect such as fade-in or fade-out by a user operation, the rectangular wave signal generation unit 270 reduces the increase rate / decrease rate of the duty ratio of the rectangular wave signal. Thus, the time taken for the voltage value of the target voltage to reach a value corresponding to the dimming rate can be extended, and special lighting effects such as fade-in and fade-out can be generated.

  Thus, the rectangular wave signal generation unit 270 determines that the voltage value of the target voltage generated by the integration circuit 172 reaches a value corresponding to the dimming rate indicated by the dimming signal until a predetermined time has elapsed. By delaying, the duty ratio of the generated rectangular wave signal is changed so that the peak of overshoot can be suppressed.

FIG. 9 is a waveform diagram showing another example of a waveform such as a voltage of each part of the power supply device 100 according to this embodiment.
In this example, the rectangular wave signal generation unit 270 changes the duty ratio of the generated rectangular wave signal stepwise.
At time t _1, when the dimmer rate of the dimmer signal instructs to change to 100%, the rectangular wave signal generation unit 270, a duty ratio of the rectangular wave signal generated, from the duty ratio corresponding to the dimming ratio of 100% When the current flowing through the light source circuit 830 is small and the dimming rate is 100%, the duty ratio is set to be approximately equal to the current that should flow through the light source circuit 830.
At time t _9, the rectangular wave signal generation unit 270, a duty ratio of the rectangular wave signal to generate slightly larger, second overshoot source circuit when the current flowing in the light source circuit 830 is the dimming ratio of 100% at the peak of 830 is set to a duty ratio that is approximately equal to the current that should flow.
At time t _10, the rectangular wave signal generation unit 270, and further increase the duty ratio of the rectangular wave signal generated, to the duty ratio corresponding to the dimming ratio of 100%.

The voltage value of the target voltage is the integration circuit 172 generates a little later than the change of the duty ratio of the rectangular wave signal changes, at time t _3, reaches a value corresponding to the dimming ratio of 100%.

  Thus, the rectangular wave signal generation unit 270 may be configured to increase the duty ratio of the rectangular wave signal to be generated in a stepwise manner. By changing the duty ratio of the rectangular wave signal at an appropriate timing, it is possible to reduce the peak of overshoot and prevent the occurrence of flashing phenomenon or failure.

  If the overshoot peak can be reduced, the rectangular wave signal generation unit 270 is not limited to a configuration that suppresses the increase rate of the duty ratio to a predetermined increase rate or less, or a configuration that increases the duty ratio stepwise. A configuration in which the duty ratio of the rectangular wave signal is changed in different ways, such as increasing or decreasing the duty ratio, may be employed. Further, the rectangular wave signal generation unit 270 may be configured to change not only the duty ratio of the rectangular wave signal but also the frequency.

FIG. 10 is a waveform diagram showing still another example of a waveform such as a voltage of each part of the power supply device 100 according to this embodiment.
As described above, the rectangular wave signal generation unit 270 may be configured to repeatedly increase or decrease the duty ratio of the generated rectangular wave signal instead of monotonously increasing or decreasing monotonously. Thus, by changing the rectangular wave signal at an appropriate timing, it is possible to suppress the peak of overshoot and shorten the time required for the current flowing through the light source circuit 830 to converge to the target value.

  As a method of changing the rectangular wave signal most appropriately, for example, a program for measuring the feedback characteristic of the power supply device 100 at the time of manufacturing the power supply device 100 and changing the rectangular wave signal most appropriately based on the measured feedback characteristic. Is created and stored in the storage device of the microcomputer 200. The rectangular wave signal generation unit 270 changes the duty ratio and frequency of the generated rectangular wave signal when the processing device executes the program stored in the storage device.

  Or power supply device 100 is good also as composition which learns how to change the most suitable rectangular wave signal based on control history. For example, a control history storage unit is further provided. The control history storage unit inputs the load current detection voltage generated by the load current detection circuit 140 when the processing device controls the input device. The control history storage unit measures the maximum value of the current flowing through the light source circuit 830, the time taken for the current flowing through the light source circuit 830 to converge to the target value, and the like when the processing device processes the data. The control history storage unit writes the measured current maximum value and convergence time into the storage device as a control history when the processing device controls the storage device. The rectangular wave signal generation unit 270 changes the rectangular wave signal with a plurality of patterns. The rectangular wave signal generation unit 270 reads out the control history stored corresponding to each pattern from the storage device by the processing device controlling the storage device. The rectangular wave signal generation unit 270 determines which pattern is most appropriate when the processing device processes the data. For example, the rectangular wave signal generation unit 270 determines that a pattern in which the maximum value of the current flowing through the light source circuit 830 is equal to or less than a predetermined threshold and the convergence time is minimum is the most appropriate pattern. When a pattern satisfying a predetermined condition such as the upper limit value of the convergence time can be found, the rectangular wave signal generation unit 270 changes the rectangular wave signal with the pattern thereafter. When a pattern satisfying the condition cannot be found, the rectangular wave signal generation unit 270 generates a plurality of patterns in which parameters such as timing for changing the duty ratio are gradually changed based on the pattern determined to be most appropriate. . The rectangular wave signal generation unit 270 changes the rectangular wave signal with the plurality of generated patterns and searches for a more appropriate pattern.

  In this way, by changing the rectangular wave signal generated by the rectangular wave signal generation unit 270 at an appropriate timing, the peak of overshoot of the current flowing through the light source circuit 830 can be suppressed and converged to the target value quickly.

Embodiment 3 FIG.
A third embodiment will be described with reference to FIGS.
In addition, about the part which is common in Embodiment 1 and Embodiment 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  Since the structure of the lighting fixture 800 and the functional block configuration of the power supply device 100 in this embodiment are the same as those described in Embodiment 1, the description thereof is omitted here.

FIG. 11 is a circuit diagram showing an example of a specific circuit configuration of the power supply device 100 according to this embodiment.
The target voltage generation circuit 170 includes a corresponding voltage generation unit 275 instead of the rectangular wave voltage generation circuit 171 described in the first embodiment.

The corresponding voltage generation unit 275 (corresponding voltage generation circuit) generates a voltage having a voltage value corresponding to the dimming degree indicated by the dimming signal input by the dimming signal input circuit 150 (hereinafter referred to as “corresponding voltage”). To do.
An output device (not shown) of the microcomputer 200 has a digital-analog conversion circuit (hereinafter referred to as “DAC”). The DAC generates a voltage having a voltage value proportional to the numerical value represented by the data based on the control by the processing device, and outputs the voltage to the outside of the microcomputer 200.
The corresponding voltage generation unit 275 reads the dimming data generated by the dimming signal input unit 250 from the storage device when the processing device controls the storage device. The corresponding voltage generation unit 275 generates and outputs a corresponding voltage having a voltage value corresponding to the dimming rate represented by the read dimming data when the processing device controls the DAC.

  The integration circuit 172 integrates the corresponding voltage generated by the corresponding voltage generation unit 275 to generate a target voltage.

FIG. 12 is a waveform diagram showing an example of a waveform such as a voltage of each part of the power supply apparatus 100 according to this embodiment.
The horizontal axis indicates time. The vertical axis indicates the dimming rate, voltage value, and current value.
A solid line 501 indicates the dimming rate indicated by the dimming signal input by the power supply apparatus 100. A solid line 508 indicates the voltage value of the corresponding voltage generated by the corresponding voltage generation unit 275. A solid line 503 indicates the voltage value of the target voltage generated by the integration circuit 172. A solid line 505 indicates a current value of a direct current flowing through the light source circuit 830.
A broken line 511 indicates a dimming rate of 100%. A broken line 520 indicates the voltage value of the corresponding voltage corresponding to the dimming rate of 100%. A broken line 513 indicates a voltage value of the target voltage corresponding to the dimming rate of 100%. A broken line 514 indicates the upper limit of the increase rate of the target voltage. A broken line 515 indicates the current value of the direct current flowing through the light source circuit 830 when the load current detection voltage generated by the load current detection circuit 140 matches the target voltage generated by the integration circuit 172.

As described above, instead of the rectangular wave voltage generation circuit 171 generating the rectangular wave voltage, the corresponding voltage generation unit 275 generates the corresponding voltage, and the integration circuit 172 integrates the corresponding voltage instead of the rectangular wave voltage to obtain the target Even when the voltage is generated, the same target voltage as in the first embodiment can be generated.
As a result, it is possible to reduce the peak of the overshoot caused by the delay associated with the feedback control, and to prevent the occurrence of flashing phenomenon or failure.

  The configuration of the first embodiment can use an inexpensive microcomputer 200 that does not have a DAC, so that the material cost of the power supply device 100 can be suppressed. On the other hand, the configuration of this embodiment can reduce the number of parts to be connected to the outside of the microcomputer 200, so that the assembly cost of the power supply apparatus 100 can be suppressed and the reliability can be improved.

  Further, the voltage value of the corresponding voltage generated by the corresponding voltage generation unit 275 is changed in the same manner as the duty ratio of the rectangular wave signal generated by the rectangular wave signal generation unit 270 described in the second and third embodiments. It may be a configuration. If it does so, the effect similar to the effect demonstrated in Embodiment 2 or Embodiment 3 can be acquired.

In the above embodiment,
A DC power supply circuit that generates DC power to be supplied to the load circuit;
A load current detection circuit that detects a load current flowing through the load circuit and generates a load current detection voltage having a voltage value proportional to the current value of the detected load current;
A target voltage generation circuit that generates a target voltage based on a target value of a load current flowing through the load circuit;
A feedback signal generation circuit that compares the voltage value of the load current detection voltage generated by the load current detection circuit with the voltage value of the target voltage generated by the target voltage generation circuit and generates a feedback signal indicating which is greater; Have
The DC power supply circuit receives the feedback signal generated by the feedback signal generation circuit, and based on the input feedback signal, when the load current detection voltage is larger than the target voltage, reduces the generated DC power, If the load current detection voltage is smaller than the target voltage, increase the generated DC power,
The target voltage generation circuit includes:
When the target value of the load current flowing through the load circuit becomes high, a target voltage having a voltage value smaller than the voltage value corresponding to the target value is generated until a predetermined time elapses. After a lapse of time, a target voltage having a voltage value corresponding to the target value is generated,
A rectangular wave voltage generating circuit for generating a rectangular wave voltage having a duty ratio corresponding to a target value of a load current flowing through the load circuit;
A power supply apparatus has been described that includes an integration circuit that integrates a rectangular wave voltage generated by the rectangular wave voltage generation circuit to generate the target voltage.

In the above embodiment,
A DC power supply circuit that generates DC power to be supplied to the load circuit;
A load current detection circuit that detects a load current flowing through the load circuit and generates a load current detection voltage having a voltage value proportional to the current value of the detected load current;
A target voltage generation circuit that generates a target voltage based on a target value of a load current flowing through the load circuit;
A feedback signal generation circuit that compares the voltage value of the load current detection voltage generated by the load current detection circuit with the voltage value of the target voltage generated by the target voltage generation circuit and generates a feedback signal indicating which is greater; Have
The DC power supply circuit receives the feedback signal generated by the feedback signal generation circuit, and based on the input feedback signal, when the load current detection voltage is larger than the target voltage, reduces the generated DC power, If the load current detection voltage is smaller than the target voltage, increase the generated DC power,
The target voltage generation circuit includes:
When the target value of the load current flowing through the load circuit becomes high, a target voltage having a voltage value smaller than the voltage value corresponding to the target value is generated until a predetermined time elapses. After a lapse of time, a target voltage having a voltage value corresponding to the target value is generated,
When the target value of the load current flowing through the load circuit becomes high, a rectangular wave voltage having a duty ratio smaller than the duty ratio corresponding to the target value is generated until a predetermined time elapses. A rectangular wave voltage generating circuit for generating a rectangular wave voltage having a duty ratio corresponding to the target value after the time elapses,
A power supply apparatus has been described that includes an integration circuit that integrates a rectangular wave voltage generated by the rectangular wave voltage generation circuit to generate the target voltage.

In the above embodiment,
A DC power supply circuit that generates DC power to be supplied to the load circuit;
A load current detection circuit that detects a load current flowing through the load circuit and generates a load current detection voltage having a voltage value proportional to the current value of the detected load current;
A target voltage generation circuit that generates a target voltage based on a target value of a load current flowing through the load circuit;
A feedback signal generation circuit that compares the voltage value of the load current detection voltage generated by the load current detection circuit with the voltage value of the target voltage generated by the target voltage generation circuit and generates a feedback signal indicating which is greater; Have
The DC power supply circuit receives the feedback signal generated by the feedback signal generation circuit, and based on the input feedback signal, when the load current detection voltage is larger than the target voltage, reduces the generated DC power, If the load current detection voltage is smaller than the target voltage, increase the generated DC power,
The target voltage generation circuit includes:
When the target value of the load current flowing through the load circuit becomes high, a target voltage having a voltage value smaller than the voltage value corresponding to the target value is generated until a predetermined time elapses. After a lapse of time, a target voltage having a voltage value corresponding to the target value is generated,
A corresponding voltage generating circuit that generates a DC voltage having a voltage value corresponding to a target value of a load current flowing through the load circuit;
A power supply apparatus has been described that includes an integration circuit that integrates a DC voltage generated by the corresponding voltage generation circuit to generate the target voltage.

In the above embodiment,
A DC power supply circuit that generates DC power to be supplied to the load circuit;
A load current detection circuit that detects a load current flowing through the load circuit and generates a load current detection voltage having a voltage value proportional to the current value of the detected load current;
A target voltage generation circuit that generates a target voltage based on a target value of a load current flowing through the load circuit;
A feedback signal generation circuit that compares the voltage value of the load current detection voltage generated by the load current detection circuit with the voltage value of the target voltage generated by the target voltage generation circuit and generates a feedback signal indicating which is greater; ,
A control power supply circuit that generates control power and supplies the generated control power to the DC power supply circuit and the target voltage generation circuit;
The DC power supply circuit receives the feedback signal generated by the feedback signal generation circuit, and based on the input feedback signal, when the load current detection voltage is larger than the target voltage, reduces the generated DC power, If the load current detection voltage is smaller than the target voltage, increase the generated DC power,
When the target value of the load current flowing through the load circuit becomes high, the target voltage generation circuit has a target voltage having a voltage value smaller than the voltage value corresponding to the target value until a predetermined time elapses. After the predetermined time has elapsed, a target voltage having a voltage value corresponding to the target value is generated,
The DC power supply circuit operates with the control power supplied by the control power supply circuit,
The target voltage generation circuit generates the target voltage from the control power supplied by the control power supply circuit,
The control power supply circuit is a power supply apparatus that does not supply control power to the DC power supply circuit and the target voltage generation circuit when a target value of a load current flowing through the load circuit is 0. explained.

In the above embodiment,
The power supply apparatus further includes a control power supply circuit that generates control power and supplies the generated control power to the DC power supply circuit and the target voltage generation circuit,
The DC power supply circuit operates with the control power supplied by the control power supply circuit,
The target voltage generation circuit generates the target voltage from the control power supplied by the control power supply circuit,
The control power supply circuit is a power supply apparatus that does not supply control power to the DC power supply circuit and the target voltage generation circuit when a target value of a load current flowing through the load circuit is 0. explained.

In the above embodiment,
A DC power supply circuit that generates DC power to be supplied to the load circuit;
A load current detection circuit that detects a load current flowing through the load circuit and generates a load current detection voltage having a voltage value proportional to the current value of the detected load current;
A target voltage generation circuit that generates a target voltage based on a target value of a load current flowing through the load circuit;
A feedback signal generation circuit that compares the voltage value of the load current detection voltage generated by the load current detection circuit with the voltage value of the target voltage generated by the target voltage generation circuit and generates a feedback signal indicating which is greater; Have
The DC power supply circuit receives the feedback signal generated by the feedback signal generation circuit, and based on the input feedback signal, when the load current detection voltage is larger than the target voltage, reduces the generated DC power, If the load current detection voltage is smaller than the target voltage, increase the generated DC power,
The target voltage generation circuit includes:
When the target value of the load current flowing through the load circuit becomes high, a target voltage having a voltage value smaller than the voltage value corresponding to the target value is generated until a predetermined time elapses. After a lapse of time, a target voltage having a voltage value corresponding to the target value is generated,
A power supply apparatus has been described in which the target voltage is gradually decreased at a rate lower than a predetermined rate when the target value of the load current flowing through the load circuit becomes low.

In the above embodiment,
The target voltage generation circuit is configured to reduce the target voltage gradually at a reduction rate lower than a predetermined reduction rate when a target value of a load current flowing through the load circuit becomes low. explained.

In the above embodiment,
The target voltage generation circuit gradually increases the voltage value of the target voltage to be generated at an increase rate lower than a predetermined increase rate when the target value of the load current flowing through the load circuit becomes high. The power supply device is described.

In the above embodiment,
The target voltage generation circuit receives a target instruction signal that indicates a target value of a load current flowing through the load circuit, and generates the target voltage based on the input target instruction signal. explained.

In the above embodiment,
The power supply device includes: a light source circuit that receives the supply of DC power generated by the power supply device as the load circuit, applies the supplied DC power to a light source, and turns on the light source. Illustrated lighting fixtures.

  DESCRIPTION OF SYMBOLS 100 Power supply device, 110 DC power supply circuit, 111 Rectifier circuit, 112 Power factor improvement circuit, 113 Buck circuit, 114 Drive circuit, 117,118 Control IC, 140 Load current detection circuit, 150 Dimming signal input circuit, 160 Control power supply circuit , 161 Control power supply generation circuit, 162 switching circuit, 163 step-down circuit, 170 target voltage generation circuit, 171 rectangular wave voltage generation circuit, 172 integration circuit, 180 feedback signal generation circuit, 200 microcomputer, 250 dimming signal input unit, 260 power supply Signal generator, 270 Rectangular wave signal generator, 275 Corresponding voltage generator, 501 to 508 Solid line, 511 to 520 Broken line, 800 Lighting fixture, 810 Main body, 821 Connector, 822 Power line, 823 Wiring, 830 Light source circuit, 831 Light source Substrate, 832 light source, 850 dimming core Troller, A81 error amplifier, AC AC power supply, C24, C34 smoothing capacitor, C43, C74 capacitor, D23 diode, D32 freewheeling diode, DB1 diode bridge, L21, L33 choke coil, PC1 photocoupler, Q22, Q31, Q61, Q64, Q71 switching element, R41 current detection resistor, R42, R62, R63, R72, R73 resistor, R51 pull-up resistor.

Claims (5)

A DC power supply circuit that generates DC power to be supplied to the load circuit;
A load current detection circuit that detects a load current flowing through the load circuit and generates a load current detection voltage having a voltage value proportional to the current value of the detected load current;
A target voltage generation circuit that generates a target voltage based on a target value of a load current flowing through the load circuit;
A feedback signal generation circuit that compares the voltage value of the load current detection voltage generated by the load current detection circuit with the voltage value of the target voltage generated by the target voltage generation circuit and generates a feedback signal indicating which is greater; ,
A control power supply circuit that generates control power and supplies the generated control power to the DC power supply circuit and the target voltage generation circuit;
The DC power supply circuit receives the feedback signal generated by the feedback signal generation circuit, and based on the input feedback signal, when the load current detection voltage is larger than the target voltage, reduces the generated DC power, If the load current detection voltage is smaller than the target voltage, increase the generated DC power,
The DC power supply circuit operates with the control power supplied by the control power supply circuit,
The target voltage generation circuit generates the target voltage from the control power supplied by the control power supply circuit,
The power supply apparatus according to claim 1, wherein the control power supply circuit does not supply control power to the DC power supply circuit and the target voltage generation circuit when a target value of a load current flowing through the load circuit is zero.   2. The target voltage generation circuit according to claim 1, wherein when the target value of the load current flowing through the load circuit becomes low, the target voltage is gradually reduced at a reduction rate lower than a predetermined reduction rate. The power supply described.   The target voltage generation circuit gradually increases the voltage value of the target voltage to be generated at an increase rate lower than a predetermined increase rate when the target value of the load current flowing through the load circuit becomes high. The power supply device according to claim 1.   The target voltage generation circuit receives a target instruction signal indicating a target value of a load current flowing through the load circuit, and generates the target voltage based on the input target instruction signal. The power supply device according to claim 3.   5. The power supply device according to claim 1, and the DC power generated by the power supply device as the load circuit are supplied, the supplied DC power is applied to the light source, and the light source is turned on. And a light source circuit.

Images