JP2011205868A - Overcurrent preventing power supply apparatus and lighting fixture using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overcurrent preventing power supply apparatus for turn on a lighting load by using a constant current unit to be driven by a voltage received from a constant voltage unit, which prevents the control operation of the constant voltage unit from being stopped due to an overcurrent when the constant current unit starts after the constant voltage unit starts supply voltage.SOLUTION: The power supply apparatus 1 includes: a constant voltage unit 2 for outputting a constant voltage; a constant current unit 3 and a timer 4 for measuring the time elapsed since the constant voltage unit 2 starts supplying voltage. The timer 4 measures the time until the start of the operation of each of the units 2 and 3, and transmits operation start signals Sb, Sa to the units 2, 3 respectively, when the elapsed time of each of the units reaches a predetermined time. The operation start signals Sb, Sa allow the constant current unit 3 to start operation before constant voltage control operation of the constant voltage unit 2. Thus, the control operation of the constant current unit 2 can be prevented from being stopped due to an overcurrent caused when the constant current unit 3 starts operation.

Description

  The present invention relates to an overcurrent prevention type power supply device and a lighting fixture using the same.

  An example of a conventional lighting fixture using this type of power supply device is shown in FIG. 12 (see, for example, Patent Document 1). This lighting fixture includes a lighting load 11 as a light source unit and a lighting device 12. The lighting device 12 includes a rectifier circuit unit 13, a PFC (power factor correction) circuit unit (corresponding to a constant voltage unit) 14, and a current output. Unit (corresponding to a constant current unit) 15 and a light control circuit unit 16.

  The PFC circuit unit 14 includes a choke coil L1, a switching element Q1 composed of an FET, a source resistor R1, a diode D1, and a capacitor C1, and a PFC control unit 17, and a constant voltage is supplied to the current output unit 15. It is a constant voltage source for output.

  The current output unit 15 includes a step-down chopper circuit including a switching element Q1, a choke coil L3, a diode D2, and a capacitor C2, a current detection resistor R6, and a current control unit 18, and supplies a constant current to the lighting load 11. It is a constant current source that outputs. The dimming circuit unit 16 controls the lighting load 11 by driving the switching element Q3 by the dimming control unit 19.

  In the lighting apparatus, the current output unit 15 operates at a constant current based on the output voltage from the PFC circuit unit 14 fed from an AC power supply (AC) and supplies a constant current to the lighting load. At this time, if the operating states of the PFC circuit unit 14 and the current output unit 15 do not match, an overcurrent flowing at the time of start-up causes a start-up failure, or sometimes each circuit element such as the PFC circuit unit 14 exceeds the rating. Current and voltage stress may be applied, and circuit elements may be damaged.

  The operation will be described below. Immediately after the AC power is turned on, the capacitor C1 of the PFC circuit unit 14 is not charged, and no current flows through the coil L3 of the current output unit 15. Therefore, immediately after the AC power supply (AC) is turned on, the voltage V of the capacitor C1 is charged with the voltage V1 from the rectifier circuit unit 13 at time t1, as shown in FIG. Starts to rise from time t3 when the operation starts, and as time elapses, it tries to boost the voltage to a desired voltage Vo determined by the PFC control unit 17. The voltage V1 is a peak value voltage of the AC power supply, and is about 141 V in the case of AC 100 volts (V).

  The current control unit 18 controls the output of the current output unit 15 to be a desired rated current based on the current detection voltage by the resistor R6. For this reason, when the current control unit 18 starts constant current control in a region where the voltage of the capacitor C1 is low, an overcurrent having a large peak value is drawn from the capacitor C1 serving as a power source.

  For example, as shown in FIG. 13B, when the current output unit 15 starts constant current operation at time tp when the PFC circuit unit 14 starts operation, the peak current Ipeak causes the capacitor C1 to Overcurrent is drawn, and the amount of feedback detected by the PFC control unit 17 suddenly increases and exceeds the allowable control range. For this reason, the operation of the PFC control unit 17 does not function and an abnormal state occurs, and the chopper circuit operation of the PFC circuit unit 14 may be stopped due to an abnormality detection function or the like by the IC circuit. Further, due to the stop of the chopper circuit operation, the voltage returns to the voltage V1 again after the time tp and cannot be boosted.

  At this time, the input supply voltage to the current output unit 15 is fixed at the voltage V1 after the time t4, and the high current Io1 is maintained even though it is originally intended to be reduced to the rated current value Io2. The stress on each element increases. For this reason, the current output unit 15 itself can be forcibly stopped by an abnormality detection function such as an IC circuit. However, as indicated by a dotted line, the output current I is reduced to zero, so that the illumination load 11 cannot be turned on.

  In particular, in the case of PFC control, in order to prevent an inrush current, a soft start function that gradually charges the capacitor C1 is often employed, so that the current output unit 15 is lower during charging. Starting with voltage, overcurrent is likely to occur.

  Further, when the lighting device is divided and connected to a constant voltage unit composed of an AC power source, a rectifier circuit unit 13 and a PFC circuit unit 14 and a constant current unit composed of a current output unit 15 and a dimming circuit unit 16 The power source for each control circuit in the constant current unit is formed using the output voltage of the constant voltage unit. At this time, the startup sequence is in the order of the PFC control unit 17 and the current control unit 18, and problems such as the constant voltage operation stop due to the peak current become remarkable.

  In addition, when the constant voltage unit and the constant current unit are separate, when a plurality of constant current units are connected to one constant voltage unit, the overcurrent flowing from the capacitor C1 further increases.

JP 2009-80995 A

  The present invention solves the above-described problem. In an overcurrent prevention type power supply device that lights a lighting load by a constant current unit driven by receiving a voltage from a constant voltage unit, the voltage after the voltage supply start by the constant voltage unit is started. An object of the present invention is to provide an overcurrent prevention type power supply device and a lighting fixture that prevent a control operation of a constant voltage unit from being stopped due to an overcurrent associated with activation of the constant current unit.

  In order to achieve the above object, an overcurrent prevention type power supply apparatus according to the present invention includes a constant voltage unit that outputs a constant voltage, a constant current unit that is driven by receiving a voltage from the constant voltage unit, and the constant voltage unit. A timer for measuring an elapsed time after the start of voltage supply by the constant current unit, wherein the constant current unit starts an operation before an elapsed time measured by the timer elapses a predetermined time. It is characterized by.

  In this overcurrent prevention type power supply device, there are a plurality of timers, and the timers start to operate with the voltage or current generated in the constant voltage unit, and after the elapse of a predetermined time, the constant current unit, the constant voltage unit, In addition, it is preferable to transmit a signal for starting each operation.

  In this overcurrent prevention type power supply device, the constant voltage unit has a boost chopper circuit that boosts the input voltage and a control circuit for driving the boost chopper circuit, and the control circuit has an operation start time of the boost chopper circuit. Is preferably later than the operation start time of the constant current unit.

  The lighting fixture of the present invention includes the above-described overcurrent-preventing power supply device, a lighting load, and a connection portion that connects the power supply device and the lighting load.

  According to the overcurrent prevention type power supply device of the present invention, a constant current unit can be started to operate a certain time before using a timer as a time until the constant voltage unit starts to operate. . Therefore, it is possible to prevent the constant voltage operation of the constant voltage unit from being stopped due to the influence of the overcurrent due to the peak current at the start of the operation of the constant current unit, and to start up the entire circuit.

The block diagram of the lighting fixture using the overcurrent prevention type power supply device which concerns on the 1st Embodiment of this invention. The circuit diagram of the constant voltage unit in the apparatus of the embodiment. The circuit diagram of the constant current unit in the apparatus of the embodiment. (A) is a figure which shows the output voltage waveform of an identification voltage unit, (b) is a figure which shows the output current waveform of an identification current unit, (c) is a figure which shows the output voltage waveform of the counter in a timer, (d) is a timer The figure which shows the output voltage waveform of the other counter in. The block diagram of the constant voltage unit in the modification of the embodiment. The circuit diagram of an identification voltage unit. (A) is a figure which shows the output waveform of the step-up chopper part of an identification voltage unit, (b) is a figure which shows the output waveform of the step-down chopper part of an identification voltage unit, (c) is a figure which shows the output current waveform of an identification current unit . The circuit diagram of the constant voltage unit in the apparatus which concerns on the 2nd Embodiment of this invention. The circuit diagram of the constant current unit in the apparatus of the embodiment. The block diagram of the lighting fixture using the apparatus which concerns on the 3rd Embodiment of this invention. The perspective view which shows the other form of the lighting fixture. The block diagram of the conventional lighting fixture. (A) is a figure which shows the output voltage waveform of the PFC circuit part in the lighting fixture, (b) is a figure which shows the output current waveform of the current output part in the lighting fixture.

(First embodiment)
An overcurrent prevention type power supply device according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, an overcurrent prevention type power supply device 1 (hereinafter referred to as a power supply device) of this embodiment includes a constant voltage unit 2 that is supplied with power from an AC power supply (AC) and outputs a constant voltage, and a constant voltage unit. 2 is provided with a constant current unit 3 that receives the voltage from 2 and drives the lighting load 5 to light and a timer 4. The timer 4 measures the elapsed time after starting the voltage supply by the constant voltage unit 2. Here, the power supply device 1 and the lighting load 5 constitute a lighting fixture. A configuration in which the constant current unit 3 and the lighting load 5 are integrated into the lamp 6 and the constant voltage unit 2 and the lamp 6 are separated and wired is also possible. The timer 4 can be built in the constant voltage unit 2 or the constant current unit 3.

  The illumination load 5 uses an organic EL light emitting element, but may be any light source that is lit with a direct current, including other solid light emitting elements such as LED light emitting elements.

  As shown in FIG. 2, the constant voltage unit 2 includes an input unit (connection unit) 20, a low-pass filter (LPF) 21, a rectifier circuit unit 22, a control power supply circuit 23, and a boost chopper unit (boost chopper circuit). 24 and an output unit (connection unit) 25. The input unit 20 is connected to an AC power source (AC), and the LPF 21 removes the high-frequency component in order to make the AC voltage from the input unit 20 sine wave. The rectifier circuit unit 22 performs full-wave rectification of the AC voltage from the LPF 21 using a diode bridge (DB). The control power supply circuit 23 connects a series circuit of resistors R4 and R5 to both output terminals of the rectifier circuit unit 22, and connects a Zener diode ZD1 in parallel to the resistor R5 to generate a constant voltage source Vcc to be supplied to the control circuit. For supplying power to the step-up chopper 24 and the like.

  The step-up chopper unit 24 controls the choke coil L1, the switching element Q1 composed of an n-channel MOSFET, the diode D1, the drive circuit 26 that drives the switching element Q1, the AND circuit AND1, and the drive circuit 26. And a constant voltage control unit (control circuit) 27. The choke coil L1 forms a series circuit with the diode D1 and is connected between the output of the rectifier circuit unit 22 and the output unit 25 having an output connector. The connection point between the choke coil L1 and the diode D1 is a switching element Q1 and a resistor. It is grounded through a series circuit with R1.

  A series circuit of a diode D1 and an electric field capacitor C1 is connected in parallel with the series circuit of the switching element Q1 and the resistor R1. Further, both ends of the capacitor C1 are connected in parallel with a series circuit of resistors R2 and R3 and to the output unit 25. The secondary coil L2 coupled to the choke coil L1 has one end connected to the constant voltage control unit 27 and the other end grounded, and detects the voltage generated in the choke coil L1. Supply control power voltage. The switching element Q1 is driven by an output signal from the drive circuit 26 that is generated based on a control signal from the constant voltage control unit 27.

  The drive circuit 26 is connected to the output of the AND circuit AND1. The AND circuit AND1 receives the voltage control signal from the constant voltage control unit 27 and the control signal from the timer 4 and outputs the logical product of these to the drive circuit 26.

  The AND 1 applies the voltage control signal from the constant voltage control unit 27 to the drive circuit 26 as it is when the input from the counter 42 (described later) of the timer 4 is high (H) level. At this time, the switching element Q1 is driven by an output signal from the drive circuit 26 that is generated based on the voltage control signal from the constant voltage control unit 27. When the input from the counter 42 is at a low (L) level, the output of the drive circuit 26 becomes zero and the switching element Q1 is stopped.

  The resistors R2 and R3 are detection resistors for detecting the output voltage V. The resistors R2 and R3 divide both ends of the capacitor C1 and use the voltage of the resistor R3 as a detection voltage. A connection point between the resistors R2 and R3 is connected to the constant voltage control unit 27 for feedback control of the output voltage V.

  The constant voltage control unit 27 receives the detection voltage from the resistor R3 as a feedback control signal, and generates a voltage control signal for setting the output voltage V of the capacitor C1 to a desired voltage value Vo based on the detection voltage. The drive circuit 26 and the switching element Q1 are controlled. This voltage control signal is formed by a PWM control signal, and controls the drive circuit 26, and the drive circuit 26 drives the switching element Q1 in pulses with the PWM signal. The output of the switching element Q1 is charged in the capacitor C1, and a DC output voltage V having a constant voltage Vo is obtained. Note that the switching frequency of PWM is several tens KHz to several MHz.

  Further, the constant voltage control unit 27 can use the voltage generated in the resistor R1 to forcibly turn off when the current flowing through the switching element Q1 reaches a predetermined peak value. In addition, the switching element Q1 can be forcibly turned on by detecting the timing when the current becomes zero using the winding voltage of the coil L2.

  The constant voltage unit 2 feeds back the output voltage V to the constant voltage control unit 27, thereby repeatedly turning on and off the switching element Q1 so that the voltage generated in the resistor R3 becomes a desired value. The output voltage V can be set to the constant voltage Vo while improving the distortion.

  The timer 4 includes a plurality of counters 41 and 42, a series circuit of resistors Ra and Rb connected in parallel to the output of the rectifier circuit unit 22 of the constant voltage unit 2, and a capacitor Ca connected in parallel to the resistor Rb. . The timer 4 starts to operate with a voltage or current generated in the constant voltage unit 2, and after a predetermined time elapses, a signal for starting operation is sent to the constant current unit 3 and the constant voltage unit 2, respectively. introduce. Here, the series circuit of the resistor Ra and the resistor Rb serves as a voltage detection circuit for the counters 41 and 42 to detect the measurement start timing. The timer 4 has a control unit (not shown) such as a microcomputer for controlling the plurality of counters 41 and 42.

  The counter 41 and the counter 42 are respectively connected to connection points of the resistor Ra and the resistor Rb, start time measurement based on the voltage of the resistor Rb, measure the elapsed time after the voltage supply start by the constant voltage unit 2, Operation start signals Sb and Sa are output to the constant voltage unit 2 and the constant current unit 3, respectively. The counters 41 and 42 operate so as to change the output from the L level to the H level after a lapse of a certain time from the start of measurement. At this time, the operation start signal Sa output from the counter 41 is input to a logical sum circuit AND2 of the constant current unit 3 described later, and the operation start signal Sb output from the counter 41 is one of inputs of AND1 in the constant voltage unit 2. .

  When the time measurement is started, the counters 41 and 42 output operation start signals Sa and Sb, respectively, after a predetermined time has elapsed. Here, the counters 41 and 42 are set to satisfy tc1 <tc2, where tc1 is the time counted by the counter 41 and tc2 is the time counted by the counter 42. Although the voltage at the end of the resistor Rb is used as the start signal of each counter 41, 42, the present invention is not limited to this. For example, a voltage generated at the end of the resistor R3 may be used. By doing so, a voltage detection circuit for starting time measurement can be used also, and the number of parts of the circuit can be reduced. Moreover, the form which detects not with a voltage value but with an electric current value may be sufficient.

  As shown in FIG. 3, the constant current unit 3 includes an input unit (connection unit) 30, a control power supply circuit 31, a DC-DC conversion unit 32, an output unit (connection unit) 33, and a constant current control unit 34. And a current detection unit 35.

  The input unit 30 is supplied with the output voltage V from the output unit 25 of the constant voltage unit 2 as the input voltage V to the constant current unit 3. The control power supply circuit 31 has the same configuration as the control power supply circuit 23 of the constant voltage unit 2, and includes a DC-DC conversion unit 32, a constant current control unit 34, a current detection unit 35, and the like in the constant current unit 3. A constant voltage source Vcc is supplied to the circuit.

  The DC-DC converter 32 includes a drive circuit 36, a switching element Q2 driven by the drive circuit 36, an OR circuit AND2 for switching an input signal to the drive circuit 36, a regenerative diode D2, and a choke coil. L3 and a capacitor C2. The switching element Q2 forms a series circuit with the choke coil L3 and is connected between the output of the rectifier circuit unit 22 and the output unit 33. The diode D2 is connected in the reverse direction between the connection point between the switching element Q2 and the choke coil L3 and the ground. The output side of the choke coil L3 is grounded via the capacitor C2. The capacitor C2 is connected in parallel with the series circuit of the illumination load 5 and the current detection resistor R6, the connection point between the illumination load 5 and the resistor R6 is connected to the current detection unit 35, and the other end of the resistor R6 is grounded. ing. The AND 2 receives the operation start signal Sa from the counter 41 and the current control signal from the constant current control unit 34.

  The DC-DC converter 32 forms a step-down chopper circuit, and switches the switching element Q2 at a high frequency by a current control signal from the constant current controller 34, whereby the input voltage V is changed to a voltage required for the lighting load 5. It converts and outputs from the output part 33, and the illumination load 5 is lighted.

  When the operation start signal Sa from the counter 41 is at the H level, the AND 2 outputs the current control signal composed of the on / off control signal from the constant current control unit 34 as it is, and is driven based on this on / off control signal. The switching element Q2 is driven by the circuit 36, and the constant current operation of the DC-DC converter 32 is maintained. Further, when the operation start signal Sa from the counter 41 is at the L level, the output of the AND 2 is also at the L level regardless of the current control signal from the constant current control unit 34. At this time, since the current control signal is not input to the drive circuit 36, the switching element Q2 does not operate. Therefore, the constant current operation of the DC-DC converter 32 is maintained in a stopped state.

  The current detection unit 35 receives the voltage generated in the resistor R6 due to the current of the lighting load 5, detects the output current flowing from the output unit 33 to the lighting load 5, and inputs the detected value to the constant current control unit 34. . The constant current control unit 34 controls the switching element Q2 on and off so that the current I output from the DC-DC conversion unit 32 is maintained at a desired constant value based on the detected value. The current detection unit 35 may include an amplifier circuit. The switching frequency of the on / off control signal from the constant current control unit 34 is several tens KHz to several MHz.

  Here, voltage and current waveforms during operation of the units 2 and 3 controlled by the counters 41 and 42 will be described with reference to FIGS. 4A shows the waveform of the output voltage V of the capacitor C1 when the constant voltage unit 2 is operating, and FIG. 4B shows the waveform of the output current I of the coil L3 when the constant current unit 3 is operating. 4C shows the waveform of the operation start signal Sa from the counter 41, and FIG. 4D shows the waveform of the operation start signal Sb from the counter. As described above, the time (tc1) for which the desired elapsed time is counted by the counter 41 is set shorter than the time (tc2) for which the elapsed time is counted by the counter 42. Therefore, the operation start signal Sa from the counter 41 is set. The turn-on time t2 is shorter than the turn-on time t3 of the operation start signal Sb from the counter 42.

  As shown in FIG. 4A, the output voltage V of the constant voltage unit 2 increases the output of the rectifier circuit unit 22 when the time when the AC power is turned on is t = 0, and the AC voltage is increased at time t1. The voltage V1 rises to the peak voltage V1, and the voltage V1 is output until time t3 when the boost chopper 24 starts operation. The voltage V1 is a peak value voltage of the AC power supply. In the case of AC100 (V), it is about 141V. Here, the constant voltage control unit 27 and the drive circuit 26 are supplied from the control power supply circuit 23 during the period of time t1 to t3, and the boost chopper unit 24 starts to operate at any time by the generation of the operation start signal Sb from the counter 42. Be on standby to be able to.

  The voltage V from time t3 to t4 is increased by the chopper operation of the constant voltage control unit 27 from time t3, so that the output voltage V is boosted by the boosting chopper unit 24, and the voltage V1 is constant voltage Vo predetermined at time t4. To rise. After time t4, the output voltage V of the capacitor C1 of the constant voltage unit 2 is maintained at a constant voltage Vo by feedback control of the constant voltage control unit 27.

  As shown in FIG. 4B, the DC-DC converter 32 of the constant current unit 3 is not driven until the time t2 determined by the counter 41 is reached, so that no current flows through the choke coil L3. However, since the control power supply of the constant current control unit 34 and the current detection unit 35 is set to a voltage that can be sufficiently supplied by the time t2, the operation can be started immediately after the time t2 has elapsed.

  At time t2 to t3, the constant current control unit 34 starts operation using the output voltage V1 as a power source. At this time, a peak current Ipeak larger than the rated current flows. However, during this period, the boost chopper unit 24 of the constant voltage unit 2 has not yet started operation, and therefore, feedback detection of constant voltage control due to overcurrent. The amount does not increase rapidly. Therefore, the constant voltage control unit 27 does not exceed the control allowable amount, the feedback control is not lost and the circuit operation is not disabled, and the output current I converges to a constant value Io1 corresponding to the power supply voltage V1.

  From time t3 to t4, the step-up chopper unit 24 of the constant voltage unit 2 starts operating at time t3, so that the current I gradually decreases as the output voltage V increases, and eventually the desired current value Io2 Maintained. After time t4, the feedback control of the constant current control unit 34 is continued.

  The counter 41 starts a timer operation with the voltage at the end of the resistor Rb, and maintains the L level until the time t2 when the preset elapsed time is reached. When the time t <b> 2 has elapsed, the operation start signal Sa becomes H level and the counter 41 starts earlier than the counter 42. When this operation start signal Sa is input to the constant current control AND2, the DC-DC converter 32 of the constant current unit 3 starts operating from time t2, and the output current I rises.

  The counter 42 is maintained at the L level until the time t3, which is an elapsed time longer than the time t2, and when the time t3 has elapsed, the operation start signal Sb becomes the H level. When this operation start signal Sb is input to the AND1 circuit for constant voltage control, the boost chopper unit 24 of the constant voltage unit 2 starts operating from time t3, the output voltage V is boosted from V1, and is controlled to be constant to Vo. Become so. Thereby, the start timing of the constant voltage unit 2 is separated from the start timing of the constant current unit 3.

  According to the present embodiment, the constant current unit 3 is started to operate a certain time before using the timer 4 as a time until the constant voltage unit 2 starts to operate for a predetermined time (time t3). Can be. Therefore, it is possible to prevent the constant voltage operation of the constant voltage unit 2 from being stopped due to the influence of the overcurrent due to the peak current Ipeak at the start of the operation of the constant current unit 3, and to start up the entire circuit.

  Moreover, since the plurality of timers 4 (counters 41 to 43) are provided, the operations of the units 2 and 3 can be started after an arbitrary elapsed time. As a result, when a vibration waveform appears at the rise of the output current I when switching the control circuit in each unit 2, 3, the boost chopper of the constant voltage unit 2 is viewed after a sufficient stabilization time during which the vibration falls. The operation of the unit 24 can be started, and the stability is improved.

  Further, even if there are a plurality of constant voltage circuits such as the step-up chopper unit 24 and the step-down chopper unit 28 in the constant voltage unit 2, the constant current unit 3 is not affected by overcurrent due to the start of operation of the constant current unit 3. The operation of each constant voltage circuit can be started after an appropriate time has elapsed. At this time, by setting the boost chopper unit 24 to operate last, it is possible to prevent the boost chopper circuit from coming off the feedback.

  Further, as the start of measurement by the timer 4, both the constant voltage unit 2 and the constant current unit 3 are performed based on detection of the input voltage to the boost chopper unit 24 of the constant voltage unit 2, but the operation of the constant voltage unit 2 is started. The start of time measurement up to is not necessarily limited to this. For example, the operation can be started with various signals such as a signal that the constant current unit 3 has started to operate and the output current I of the DC-DC converter 32 has fallen to a constant value. Here, it is only necessary to start the operation of the DC-DC converter 32 before starting the operation of the step-up chopper 24 and delay the start-up time of the constant voltage unit 2 from the start-up time of the constant current unit 3.

  When the time measurement for starting the operation of the step-up chopper unit 24 is set after the output current I falls within a constant value, for example, the output current Io1 (see FIG. 4B) at the time t2 to t3 is a constant value. When the operation of the step-up chopper unit 24 is started, there are advantages such as fewer circuit components in the timer 4. For example, the output current I may be detected by using the current detection resistor R 6 connected to the current detection unit 35.

(Modification of the first embodiment)
Next, a modification of the above embodiment will be described with reference to FIGS. In this modified example, the constant voltage unit 2 has a step-down chopper unit 28 that receives and lowers the output of the step-up chopper unit 24 after the step-up chopper unit 24, as shown in FIG. Is output from the output unit 25.

  As shown in FIG. 6, the step-down chopper 28 has the same configuration as the DC-DC converter 32 shown in FIG. 3, and includes a switching element Q3, a drive circuit 29 for driving the switching element Q3, and an OR circuit. The circuit includes an AND3, a diode D3, a choke coil L4, a series circuit of resistors R7 and R8 for voltage detection, and a capacitor C3. The voltage at the connection point of the resistors R7 and R8 is fed back to the constant voltage controller 27, and the voltage of the capacitor C3 is constant voltage controlled by the constant voltage controller 27 and output from the output unit 25 as the output voltage V.

  The AND 3 receives an operation start signal Sc from a counter 43 described later and another current control signal for feedback control of the output voltage V by the constant current control unit 34.

  The constant current control unit 34 steps down the voltage Vb from the step-up chopper unit 24 at a constant ratio by turning on and off the switching element Q3 at a constant frequency and a constant on time, and outputs the output voltage V to the output unit 25. Output from. For example, when the input voltage of the AC power supply AC is 100 to 242 (V), the output of the step-up chopper unit 24 is set to about 400 (V), and the step-down chopper unit 28 sets the output to 24 (V) or 48 (V). The lighting load 5 can be turned on by the constant current unit 3 in the subsequent stage with a direct current voltage.

  The timer 4 further includes a counter 43 that outputs an operation start signal Sc in addition to the counters 41 and 42. Here, the operation start signal Sa, the operation start signal Sb, and the operation start signal Sc of the outputs of the counters 41, 42, and 43 are respectively input to AND2 of the constant current unit 3 and AND1 and AND3 of the constant voltage unit 2. The

  Here, voltage and current waveforms during operation of the units 2 and 3 controlled by the counters 41, 42, and 43 will be described with reference to FIGS. 7A shows the waveform of the output voltage Vb of the step-up chopper section 24 in the constant voltage unit 2, FIG. 7B shows the waveform of the output voltage V output from the capacitor C1 of the constant voltage unit 2, and FIG. c) shows the waveform of the output current I of the coil L3 when the constant current unit 3 is in operation. In FIGS. 7A, 7B, and 7C, the time axes are shown to coincide.

  As shown in FIG. 7A, after the power supply AC is turned on, the voltage Vb rises to Vb1, which is the peak value of the power supply voltage. Here, under the control of the timer 4, each AND2 (FIG. 3) in the order of the operation start signal Sc (ON at time t2), the operation start signal Sa (ON at time t3), and the operation start signal Sb (ON at time t4). , AND3 (FIG. 6), and AND1 start operation. At this time, at a time t3 when the constant current circuit unit including the DC-DC conversion unit 32, the constant current control unit 34, and the current detection unit 35 of the subsequent constant current unit 3 starts operating, as shown in FIG. In addition, only the step-down chopper unit 28 is activated (turned on at time t2). For this reason, the constant current circuit unit operates with the voltage of the output Vb1 of the step-up chopper unit 24 and the output Vo1 of the step-down chopper unit 28. Here, since the step-up chopper unit 24 is stopped, the output Vb1 becomes the same as the output (about 141 V) of the rectifier circuit unit 22.

  In such a state, the constant current unit 3 is started, a current having a large peak value Ipeak is allowed to flow, and after the output current I of the constant current unit 3 reaches a constant value Io1, the operation of the boost chopper unit 24 is finally performed. To start. As a result, the output of the step-up chopper increases from Vb1 to Vb2, and accordingly, the output of the step-down chopper unit 28 also increases from Vo1 to Vo2.

  With these operations, the output current of the DC-DC converter 32 of the constant current unit 3 decreases from Io1 to Io2, and the rated lighting is maintained. By operating in this way, it is possible to prevent the boost chopper 24 from being stopped by the peak current Ipeak. In addition, since the output current decreases from Io1 to Io2 by starting up the boost chopper unit 24, circuit stress can be reduced.

(Second Embodiment)
An overcurrent prevention type power supply device according to a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the constant voltage unit 2 has a dimmer 7a and a dimming signal transmitter 7b, and the constant current unit 3 operates by receiving the output of the DC-DC converter 32. An output unit 8 is provided. The dimming output unit 8 is controlled by the dimming signal S1 from the constant voltage unit 2 side, and performs dimming control on the illumination load 5.

  As shown in FIG. 8, in the constant voltage unit 2, the dimming unit 7a and the dimming signal transmitting unit 7b are configured by a combination of general-purpose ICs, a microcomputer, and the like, and are operated by being supplied with power from the constant voltage source Vcc. The dimming signal S1 from the signal transmission unit 7b is transmitted from the output unit 25.

  The dimming unit 7a receives a dimming request from the outside, converts it to a dimming command value, and sends a command signal based on the dimming command value to the dimming signal transmission unit 7b. The dimming command value can be formed, for example, by changing the resistance value by the user turning the resistance volume, generating a voltage value corresponding to the resistance value with a microcomputer, and generating a control signal from the remote controller. It can also be formed.

  The dimming signal transmitter 7b receives the command signal from the dimmer 7a, generates a dimming signal S1 such as a PWM signal based on the command signal, and sends it to the constant current unit 3. The PWM signal is a 1 kHz pulse signal having an amplitude of 12 V, and the dimming rate is increased as the ON time is shorter. The dimming signal S1 when the rated output is a dimming rate of 100% may be a variable amplitude signal. Moreover, when transmitting to the constant current unit 3 side by a wired or wireless communication means, a corresponding communication conversion function may be provided.

  As shown in FIG. 9, the dimming output unit 8 includes a switching element Q4 and a drive circuit 81 that drives the switching element Q4. The switching element Q4 includes the output side of the DC-DC conversion unit 32, the output unit 33, and the like. Are connected in series. The drive circuit 81 receives the dimming signal S1 from the dimming signal transmission unit 7b, turns on and off the switching element Q4 based on the dimming signal S1, and the output is supplied from the output unit 33 to the illumination load 5. The

  According to the present embodiment, according to the dimming signal S1 from the dimming signal transmitter 7b, the current of the lighting load 5 such as an organic EL can be adjusted and adjusted to a desired level, and at the time of startup The peak current to the dimming output unit 8 is suppressed, and the dimming output unit 8 can be prevented from being damaged due to overcurrent.

  FIG. 10 shows the constant voltage unit 2 (overcurrent prevention type power supply device), a plurality of lamps (illumination loads) 6 (6a, 6b) fed by the constant voltage unit 2, the constant voltage unit 2 and the lamp 6. The structural example of the lighting fixture provided with the connection part 61 to connect is shown. The lamp 6 has a light emitting element (illumination load) 5a, a constant current unit 3, and a dimming signal receiving unit 9 together with the connection unit 61, and the constant voltage unit 2 is connected via the connection unit 61 made of a connector or the like. It is connected to the output unit by wiring. In the constant voltage unit 2, the output voltage V from the output unit and the dimming signal S1 are connected to the lamp 6 with a common ground line (GND), and the constant current unit 3 and the dimming signal receiving unit in the lamp 6 are respectively connected. 9 and.

  The light emitting element 5a is composed of one or a plurality of solid light emitting elements such as an organic EL or LED in which an input current and a light output are in a substantially proportional relationship. The dimming signal receiving unit 9 receives the dimming signal S1 from the dimming signal transmission unit 7b of the constant voltage unit 2, restores the original dimming command value, and transmits it to the constant current unit 3. The constant current unit 3 has a dimming function and receives a command value from the dimming signal receiver 9 to perform PWM dimming and amplitude dimming of the light emitting element 5a. The dimming signal receiver 9 may be provided in the constant current unit 3.

  Even when a plurality of lamps 6 are connected to the constant voltage unit 2, this lighting fixture can suppress the peak current from the constant voltage unit 2 flowing through the wiring at the start of operation. As a result, it is possible to reduce stress on the circuit elements and the like of the lamp 6 due to overcurrent, and after the lighting operation, stable illumination resistant to power supply fluctuations can be obtained. Further, the distance between the lamp 6 and the constant voltage unit 2 can be adjusted to an arbitrary length by the wiring between the constant voltage unit 2 and each connection portion 61. Moreover, since the light emitting element 5a of LED or an organic EL element was used, a planar thin luminaire can be obtained.

  FIG. 11 shows an example in which the lighting fixture is composed of a plurality of modules. This lighting fixture includes a power supply unit (power supply device) 1a obtained by modularizing the constant voltage unit 2 and the constant current unit 3, and a load module 5b obtained by modularizing a plurality of light emitting elements 5a. Due to these modularizations, the lighting fixture can be made compact, and replacement and repair can be facilitated.

  In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention. For example, in each of the above-described embodiments, a plurality of step-down chopper units 28 may be provided in the constant voltage unit 2 and three or more counters of the timer 4 may be provided to time-shift the operation start of each chopper circuit. The switching element is not limited to the FET, and other semiconductor elements such as a bipolar transistor may be used. When a plurality of lighting loads 5 are connected to one power supply device 1, the lighting loads 5 may be connected in series, in parallel, or a combination thereof. Further, although a resistor is used for current detection, a transformer or the like may be used.

1 Power supply (overcurrent prevention power supply, lighting equipment)
2 Constant voltage unit 3 Constant current unit 24 Boost chopper (boost chopper circuit)
27 Constant voltage controller (control circuit)
4 Timer 41, 42, 43 Counter (Timer)
5 Lighting load 5a Light emitting element (lighting load, lighting fixture)
6, 6a, 6b Lamp (lighting fixture)
61 Connection (lighting fixture)
Sa, Sb, Sc Operation start signal (signal)

Claims (4)

A constant voltage unit that outputs a constant voltage;
A constant current unit driven by receiving a voltage from the constant voltage unit;
A timer for measuring the elapsed time after the start of voltage supply by the constant voltage unit,
The overcurrent prevention type power supply device, wherein the constant current unit starts an operation before an elapsed time measured by the timer elapses a predetermined time. A plurality of the timers;
The timer starts operation with a voltage or current generated in the constant voltage unit, and transmits a signal for starting operation to the constant current unit and the constant voltage unit after a predetermined time elapses, respectively. The overcurrent prevention type power supply device according to claim 1, wherein: The constant voltage unit includes a boost chopper circuit that boosts an input voltage, and a control circuit for driving the boost chopper circuit,
3. The overcurrent prevention type power supply device according to claim 1, wherein the predetermined time is shorter than a time until the control circuit of the step-up chopper circuit starts to operate.   The overcurrent prevention type power supply device according to any one of claims 1 to 3, an illumination load, and a connection portion that connects the power supply device and the illumination load. Instruments.

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