JP6824752B2 - Power supply and lighting equipment with this power supply - Google Patents

Description

An embodiment of the present invention relates to a power supply device for lighting a light source unit using, for example, a light emitting diode (LED) as a light source, and a lighting device including the power supply device.

In a power supply device used in a lighting fixture using an LED as a light source, when the light source unit of the LED is turned on, for example, a voltage applied to the LED and a lamp current flowing through the LED are detected, and the lamp current is, for example, Constant current control is performed to adjust the output voltage to the LED so that it matches the rated current of the LED. Therefore, if, for example, the LED light source unit is removed or dropped during lighting, or if the signal line that supplies output power to the light source unit is disconnected, the current flowing through the light source unit is instantly zero immediately after that. Therefore, the power supply device boosts the voltage supplied to the light source unit to a voltage higher than the normal voltage, which causes a failure of the device, which is not preferable.

Therefore, the power supply device is provided with a function of detecting, for example, the current value supplied to the light source unit, and when the detected value of the supply current exceeds the threshold value, it is determined that an abnormality has occurred and the power supply device is latched and stopped. (See, for example, Patent Document 1).

Japanese Patent No. 5525393

However, the power supply device described in Patent Document 1 has the following problems to be improved. That is, the cause of the detected value of the supply current to the light source unit exceeding the threshold value is a temporary power failure or decrease of the commercial power supply voltage in addition to the above-mentioned removal, disconnection, or disconnection of the light source unit. Therefore, if the power supply unit is unconditionally latched and stopped when the supply voltage to the light source unit exceeds the threshold value, the user can power the power supply again even if the cause is a temporary power failure or drop in the commercial power supply voltage. The loading operation had to be redone, which was troublesome.

The embodiment of the present invention has been made by paying attention to the above circumstances, and appropriate protection operation is performed depending on whether the cause of the decrease in the load current of the light source unit is temporary or permanent. It is an object of the present invention to provide a power supply device capable of performing the above and a lighting device provided with the power supply device.

The power supply device according to the embodiment includes a voltage-current generation circuit that generates a variable output voltage and an output current and supplies the output current to the light source unit, and the voltage-current generation in response to a power-on operation or a reset operation for the voltage-current generation circuit. The value of the output current supplied to the light source unit from the sequence control circuit for starting the circuit in a predetermined procedure and the voltage / current generation circuit after being started by the sequence control circuit is detected, and the detected value is said. A comparison circuit that outputs a differential amplification voltage that amplifies the difference between the output current value and a preset target value, an output control circuit that controls to reduce the differential amplification voltage output from the comparison circuit, and the comparison. It includes a protection circuit that operates to protect the voltage / current generation circuit based on the differential amplification voltage output from the circuit. Then, when the differential amplification voltage output from the comparison circuit reaches a preset upper limit value continuously for a predetermined time by this protection circuit, the voltage / current generation circuit is first subjected to the reset operation, and then the reset operation is performed. by the reset operation is repeated multiple times, when the temperature of the control circuit including the sequence control circuit and the protection circuit exceeds a value corresponding to the normal range, it stops the power supply to the voltage-current generating circuit In other cases, the operating state of the voltage / current generation circuit is maintained.

The lighting device according to the embodiment includes the above-mentioned power supply device and a light source unit connected to a power supply terminal of the power supply device and controlled to be lit.

According to the embodiment, when the state in which the current value supplied to the light source unit is reduced continues for a predetermined time, the operation of the voltage / current generation circuit is reset and autonomously restarted under the control of the sequence control circuit. The latch is stopped only when the restart is repeated. Therefore, when the cause of the decrease in the load current of the light source unit is a temporary decrease in the power interruption voltage, the lighting of the light source unit can be restored without turning on the power switch again. On the other hand, the power supply device can be reliably protected even when the cause of the decrease in the load current of the light source unit is permanent such as removal or disconnection of the light source unit or disconnection of the signal line.

That is, depending on whether the cause of the decrease in the load current of the light source unit is temporary or permanent, a power supply device capable of performing appropriate protective operation and lighting provided with this power supply device are provided. Equipment can be provided.

The figure which shows the circuit structure of the lighting apparatus which concerns on one Embodiment of this invention. FIG. 3 is a block diagram showing a configuration of a control circuit included in the power supply device of the lighting device shown in FIG. The figure which shows the activation sequence by the control circuit shown in FIG. The figure for demonstrating the protection control operation of a control circuit when a signal line dropout occurs. The figure for demonstrating the protection control operation of a control circuit when a temporary drop of a power-source voltage occurs.

Hereinafter, embodiments will be described with reference to the drawings.
[One Embodiment]
(Constitution)
FIG. 1 is a circuit configuration diagram of a lighting device 100 including a power supply device 2 according to the present embodiment. Note that FIG. 1 shows a schematic circuit configuration, and some of the various elements provided in the actual circuit configuration are not shown.

The lighting device 100 includes a light source unit 1 and a power supply device 2. The light source unit 1 is a light emitting load (also referred to as a light emitting lamp) whose lighting is controlled by the power supply device 2, and is detachable from the power supply device 2. The power supply device 2 is fixedly provided in the main body of the lighting device 100.

The light source unit 1 includes a plurality of light emitting diodes (LEDs) D11 and a resistor R11. A plurality of light emitting diodes D11 are connected in series. Although not shown, the light source unit 1 is also connected to a resistance element in parallel with the light emitting diode D11. The resistor R11 is connected to the current output end of the series circuit of the light emitting diode D11. The light source unit 1 is detachably attached to the power supply device 2 at the current input end and the current output end in the series circuit of the light emitting diode D11 and at the end not connected to the light emitting diode D11 of the resistor R11, respectively. Terminals T11, T12, and T13 are provided.

The number of light emitting diodes D11 is arbitrary. The light source unit 1 may be provided with only one light emitting diode D11. Further, a plurality of series circuits of the light emitting diode D11 as shown in FIG. 1 may be connected in parallel. The light source unit 1 may use another type of solid-state light emitting device such as an organic EL (Electro Luminescence) as a light source instead of the light emitting diode D11.

The power supply device 2 receives power from an external power source 200 such as a commercial power source, and generates DC power for causing the light emitting diode D11 of the light source unit 1 connected as a load to emit light. Then, the power supply device 2 supplies the generated DC power to the light source unit 1 mounted on the power supply terminals T31, T32, and T33 to control the lighting.

The power supply device 2 includes a rectifier circuit 10, a power factor improving circuit 20, a step-down chopper circuit 30, a control circuit 40, and a mounting detection circuit 50. The power supply device 2 includes a diode D1, capacitors C1, C2, C3, C4, C5, C6, C7, and resistors R1, R2, R3, R4, R5, R6, R7, R8, R9, R101, R102, It is equipped with R103.

The pair of input ends of the rectifier circuit 10 are connected to the two power supply terminals T21 and T22, respectively. Two power supply lines connected to an external power source 200 such as a commercial power source are connected to the two power supply terminals T21 and T22 via a power supply switch (not shown). Through this connection, AC power is supplied from the external power supply 200 to the pair of input ends of the rectifier circuit 10 via the power switch. The rectifier circuit 10 rectifies AC power and outputs DC power. The DC power output by the rectifier circuit 10 between the pair of output ends is smoothed by the capacitor C1 and then supplied to the power factor improving circuit 20. One end of the capacitor C1 is connected to one of the output ends of the rectifier circuit 10, and the other end is connected to the ground which is the reference potential of the main circuit. Since the capacitance of the capacitor C1 is about several μF, the voltage across this is a pulsating voltage obtained by full-wave rectifying a sine wave.

The power factor improving circuit 20 boosts the DC power smoothed by the capacitor C1 in order to improve the power factor. The power factor improving circuit 20 is also referred to as a PFC (Power Factor Correction) circuit. The power factor improving circuit 20 includes a transformer Tr21, a switching element Q21, an electrolytic capacitor C21, a diode D21, and resistors R21 and 22.

The transformer Tr21 includes a coil L21 on the primary side and a coil L22 on the secondary side. In the transformer Tr21, the input end of the coil L21 on the primary side is connected to one end of the capacitor C1, and the output end is connected to the anode of the diode D21. In the transformer Tr21, the input end of the coil L22 on the secondary side is connected to the ground, and the output end is connected to one end of the resistor R22. One end of the resistor R22 is connected to the output end of the coil L22, and the other end is connected to the ZCD terminal of the control circuit 40.

The switching element Q21 is an N-channel field effect transistor (FET). In the switching element Q21, the drain terminal is connected to the connection point between the output end of the coil L21 and the anode of the diode D21, the source terminal is connected to one end of the resistor R21 and the CS terminal of the control circuit 40, and the gate terminal is connected. It is connected to the GD terminal of the control circuit 40. One end of the resistor R21 is connected to the source terminal of the switching element Q21, and the other end is connected to the ground. In the diode D21, the anode is connected to the connection point between the other end of the coil L21 and the drain terminal of the switching element Q21, and the cathode is connected to one end of the electrolytic capacitor C21. One end of the electrolytic capacitor C21 is connected to the cathode of the diode D21, and the other end is connected to the ground. Both terminals of the electrolytic capacitor C21 serve as output terminals of the power factor improving circuit 20.

By such a connection, a series circuit of the diode D21 and the electrolytic capacitor C21 is formed between the drain terminal and the source terminal of the switching element Q21. On the other hand, the switching element Q21 conducts when the gate signal applied to the gate terminal is turned on, and forms a closed circuit including the capacitor C1, the coil L21, and the resistor R21. Further, the switching element Q21 is opened when the gate signal applied to the gate terminal is turned off, and the closed circuit is cut off. As a result, the electrolytic capacitor C21 is charged by the voltage charged in the capacitor C1 when the switching element Q21 is in the cutoff state, and is discharged when the switching element Q21 is in the conductive state. Thus, the power factor improving circuit 20 boosts the DC voltage rectified by the rectifying circuit 10 by the switching operation of the switching element Q21, obtains a predetermined DC voltage, and outputs the DC voltage to the step-down chopper circuit 30.

The step-down chopper circuit 30 includes a switching element Q31, an inductor L31 for storing power, a capacitor C31 for output, a diode D31 for regeneration, and resistors R31 and R32. The switching element Q31 is an N-channel field effect transistor (FET). In the switching element Q31, the drain terminal is connected to one end of the electrolytic capacitor C21 which is one output terminal of the power factor improving circuit 20, the source terminal is connected to the input end of the inductor L31 and the cathode of the diode D31, and the gate terminal is connected. It is connected to the HO terminal of the control circuit 40. The inductor L31 has an input end connected to the source terminal of the switching element Q31 and an output end connected to one end of the capacitor C31. One end of the capacitor C31 is connected to the output end of the inductor L31, and the other end is connected to one end of the resistor R31. One end of the resistor R31 is connected to the other end of the capacitor C31, and the other end is connected to the anode of the diode D31. In the diode D31, the cathode is connected to the connection point between the source terminal of the switching element Q31 and the inductor, and the anode is connected to the ground.

The step-down chopper circuit 30 connects both ends of the capacitor C31 to the power supply terminals T31, T32 and T33 of the power supply device 2. Specifically, in the step-down chopper circuit 30, the side connected to the output end of the inductor L31 of the capacitor C31 is connected to the feeding terminal T31, and the side connected to the resistor R31 of the capacitor C31 is connected to the feeding terminal T33. You are connected. Further, the side of the capacitor C31 connected to the resistor R31 is connected to the power supply terminal T32 via the resistor R32.

By the way, when the light source unit 1 as a load is connected to the power supply device 2, the terminal T11 of the light source unit 1 is connected to the power supply terminal T31, and the terminal T12 of the light source unit 1 is connected to the power supply terminal T32. The terminal T13 of the light source unit 1 is connected to T33. The terminal T11 is a current input terminal of the light source unit 1. The terminal T12 is a current output terminal of the light source unit 1.

Through such a connection, the switching element Q31 conducts when the gate signal applied to the gate terminal is turned on, and guides the output current of the power factor improving circuit 20 to the inductor L31. The switching element Q31 is opened when the gate signal applied to the gate terminal is turned off, and cuts off the output current of the power factor improving circuit 20. The inductor L31 stores the DC power when the switching element Q31 is turned on and a DC voltage is applied, and releases the stored DC power when the switching element Q31 is turned off and the DC voltage is no longer applied. The DC power discharged from the inductor L31 is smoothed by the capacitor C31 and supplied to a load connected to the feeding terminals T31, T32, and T33, for example, the light source unit 1.

The mounting detection circuit 50 includes a diode D51 and resistors R51, R52, R53 and R54. In the mounting detection circuit 50, one end of the resistor R54 is connected to the VC2 terminal of the control circuit 40, the other end is connected to the anode of the diode D51, and the cathode of the diode D51 is connected to the power supply terminal T31 of the power supply device 2. .. Further, in the mounting detection circuit 50, a series resistance circuit R51-R52 is formed by the resistor R51 and the resistor R52, one end of the series resistance circuit R51-R52 is connected to the anode of the diode D51, and the other end is connected to the ground. doing. Therefore, the series resistance circuits R51-R52 are connected in parallel with the capacitor C31 of the step-down chopper circuit 30.

The mounting detection circuit 50 connects one end of the resistor R53 to the midpoint of the series resistance circuits R51-R52, and connects the other end of the resistor R53 to the Lamp terminal of the control circuit 40. Here, the mounting detection circuit 50 determines whether or not a load is connected to the power supply terminals T31, T32, and T33 of the power supply device 2 due to a change in the voltage divided by the resistance ratio of the series resistance circuits R51-R52. It is a circuit for making it possible to judge by.

The control circuit 40 is composed of an analog IC (Integrated Circuit). The control circuit 40 has a MULT terminal, a GD terminal, a ZCD terminal, a CS terminal, a Vcc terminal, a VS terminal, a HO terminal, a VB terminal, a VFB terminal, a VDC terminal, an OCP terminal, and a VC2 terminal as external terminals for connecting to the outside. It has an LGND terminal, a Vref terminal, an OP + terminal, an OP- terminal, an ABN terminal, a Lamp terminal, a COMP terminal, and a DIS terminal. Needless to say, the external terminals of the control circuit 40 are not limited to the above terminals.

The MULT terminal is connected to the midpoint of the series resistance circuits R1-R2 formed by the resistor R1 and the resistor R2. The series resistance circuits R1-R2 are connected between both terminals of the capacitor C1. Due to this connection, the potential of the MULT terminal depends on the voltage obtained by dividing the output voltage of the capacitor C1 by the resistance ratio of the series resistance circuits R1-R2. The control circuit 40 detects the input voltage to the power factor improving circuit 20 from the potential of the MULT terminal.

The GD terminal is connected to the gate terminal of the switching element Q21. The control circuit 40 generates a gate signal of the switching element Q21. Then, the control circuit 40 outputs a gate-on or gate-off gate signal from the GD terminal to the gate terminal of the switching element Q21.

The ZCD terminal is connected to the output end of the coil L22 via the resistor R22. The coil L22 supplies the ZCD terminal with a potential corresponding to the amount of change in the current flowing through the coil L21. The control circuit 40 detects the timing at which the current flowing through the coil L21 on the primary side of the transformer Tr21 becomes zero from the potential of the ZCD terminal, and generates a signal for turning on the switching element Q21.

The CS terminal is connected to the source terminal of the switching element Q21. The potential of the CS terminal depends on the current flowing between the drain and the source of the switching element Q21. The control circuit 40 detects the current flowing through the switching element Q21, the so-called switching current, from the potential of the CS terminal.

The Vcc terminal is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the VB terminal and one end of the bootstrap capacitor C2. The other end of the capacitor C2 is connected to the VS terminal and also to the source terminal of the switching element Q31. The control circuit 40 applies a predetermined circuit operating voltage Vcc to the Vcc terminal. When the potential of this circuit operating voltage Vcc is higher than the potential of the source terminal of the switching element Q31, the capacitor C2 is charged. The control circuit 40 detects the potential on one end side of the capacitor C2 (the side connected to the cathode of the diode D1) from the VB terminal, and is connected from the VS terminal to the other end side of the capacitor C2 (the source terminal of the switching element Q31). Detects the potential of the side).

The HO terminal is connected to the gate terminal of the switching element Q31. The control circuit 40 generates a gate signal of the switching element Q31 based on the potential difference between both ends of the capacitor C2. Then, the control circuit 40 outputs a gate-on or gate-off gate signal from the HO terminal to the gate terminal of the switching element Q31.

The VFB terminal is connected to the midpoint of the series resistance circuit R3-R4 formed by the resistor R3 and the resistor R4. The series resistance circuit R3-R4 is connected between both terminals of the capacitor C21. Due to this connection, the potential of the VFB terminal depends on the voltage obtained by dividing the output voltage of the capacitor C21 by the resistance ratio of the series resistance circuits R3-R4. The control circuit 40 detects the DC voltage output from the VFB terminal to the step-down chopper circuit 30 from the power factor improving circuit 20.

The VDC terminal is connected to the connection point between the cathode of the diode D21 in the power factor improving circuit 20 and the drain terminal of the switching element Q31 in the step-down chopper circuit 30. By this connection, a high voltage full-wave rectified voltage input to the power factor improving circuit 20 is applied to the VDC terminal. The control circuit 40 generates a circuit operating voltage Vcc or the like from a high voltage applied to the VDC terminal by a dropper method.

The OCP terminal is connected to the connection point between the capacitor C31 of the step-down chopper circuit 30 and the resistor R31 via the resistor R5. The potential of the OCP terminal depends on the current flowing through the resistor R5. The current flowing through the resistor R5 is the current flowing through the resistor R31 is the current flowing through the step-down chopper circuit 30. The control circuit 40 detects the current flowing through the step-down chopper circuit 30 from the potential of the OCP terminal.

The VC2 terminal is connected to the ground via the capacitor C3. Further, the VC2 terminal is connected to the power supply terminal T31 of the power supply device 2 via the resistor R54 and the diode D51. By this connection, a voltage obtained by dividing the potential of the VC2 terminal, that is, the potential corresponding to the charging voltage of the capacitor C3, is applied between the power supply terminal T31 and the power supply terminal T33 of the power supply device 2.

The LGND terminal is connected to the ground.
The Vref terminal is connected to the ground via a parallel circuit of the series resistance circuit R101-R102 formed by the resistor R101 and the resistor R102 and the capacitor C4. The OP + terminal is connected to the midpoint of the series resistance circuits R101-R102. The OP + terminal is also connected to the ground via the capacitor C5. With these connections, the potential of the OP + terminal becomes the potential of the reference voltage determined by the resistance voltage division of the resistors R101 and R102.

The OP-terminal is connected to the power supply terminal T32 of the power supply device 2 via the combined resistance of the resistors R11, R31, and R32. The potential of the OP-terminal depends on the current flowing through the resistor R9. The current flowing through the combined resistance of the resistors R11, R31, and R32 is the current flowing through the feeding terminal T31, that is, the current flowing through the light emitting diode D11 of the light source unit 1 with the light source unit 1 as a load mounted on the power supply device 2. Is. The control circuit 40 detects the current flowing through the light emitting diode D11 of the light source unit 1, the so-called load current, from the potential of the OP-terminal.

The ABN terminal is connected to the midpoint of the series resistance circuit R7-R8 formed by the resistor R7 and the resistor R8. The series resistance circuit R7-R8 is connected between the connection point between the inductor L31 of the step-down chopper circuit 30 and the capacitor C31 and the ground. That is, the series resistance circuits R7-R8 are connected in parallel with the capacitor C31. By this connection, the potential of the ABN terminal depends on the potential obtained by dividing the DC voltage supplied from the step-down chopper circuit 30 to the load by the resistance ratio of the series resistance circuits R7-R8. The control circuit 40 detects the voltage supplied from the step-down chopper circuit 30 to the light source unit 1 based on the potential of the ABN terminal.

The Lamp terminal is connected to the midpoint of the series resistance circuits R51-R52 via the resistor R53. The series resistance circuit R51-R52 is connected between the power supply terminal T31 and the power supply terminal T33 of the power supply device 2 via a diode D51 for preventing backflow. Due to this connection, the potential of the Lamp terminal depends on the voltage obtained by dividing the voltage corresponding to the potential difference between the power supply terminal T31 and the power supply terminal T33 of the power supply device 2 by the resistance ratio of the series resistance circuits R51-R52. When a load including a resistance element is connected between the power supply terminal T31 and the power supply terminal T33, a current flows through the load and the voltage between the power supply terminal T31 and the power supply terminal T33 drops. There is no voltage drop if no load is connected. The control circuit 40 detects a voltage drop between the power supply terminal T31 and the power supply output terminal T33 from the potential of the Lamp terminal.

The DIS terminal is connected to the connection point between the inductor L31 and the capacitor C31 of the step-down chopper circuit 30 via the resistor R6. A switch is built in between the DIS terminal of the control circuit 40 and the GND, and the control circuit 40 controls the switch on and off. When the switch between the DIS terminal and the GND is turned on, the voltage of the capacitor C31 is discharged through the resistor R6, and the connection point potential between the inductor L31 and the capacitor C31 drops to approximately the GND potential. Although the resistor R6 can be omitted, it is connected in order to suppress the discharge current of the capacitor C31 and relieve the stress on the switch built in between the DIS terminal and the GND. The GND is the reference potential of the control circuit 40, and is connected to the ground which is the reference potential of the main circuit via the LGND terminal.

Although not shown, the COMP terminal is an output terminal of a built-in error amplifier. The error amplifier outputs an error signal between the internal reference voltage and the VFB voltage. The on-width and frequency of the self-excited oscillation circuit are controlled by this error signal, and the output voltage of the power factor improving circuit 20 is feedback-controlled.
The capacitors C6, C7, and R103 connected to the COMP terminal are phase correction components.

By the way, the control circuit 40 is configured as follows. FIG. 2 is a circuit block diagram showing the main configuration.
That is, the control circuit 40 monitors the self-excited oscillation circuit 41, the fixed oscillation circuit 42, the selection circuit 43, the lighting control circuit 44, the protection circuit 45, the power supply circuit 46, the operational amplifier 47 as a comparison circuit, and the monitoring. A circuit 48 and a sequence control circuit 49 are provided. In the control circuit 40, each of the circuits 41 to 49 is composed of analog circuits, and these circuits are integrated into an integrated circuit. In the control circuit 40, at least a part of each circuit 41 to 49 may be composed of a digital circuit, and at least a part of the processing performed by each circuit 41 to 49 may be realized by software processing using a computer. ..

The self-oscillation circuit 41 operates by self-oscillation based on the potentials of the MULT terminal, ZCD terminal, COMP terminal, CS terminal, and VFB terminal, and is a switching signal for turning on / off the first switching element Q21 (hereinafter,). , Called the first switching signal).

The fixed oscillation circuit 42 generates a predetermined constant frequency switching signal (hereinafter, referred to as a second switching signal). Further, the fixed oscillation circuit 42 includes a circuit called a C timer that oscillates a reference oscillation signal Ctim. The reference oscillation signal Ctim gives a reference operation timing to each circuit in the control circuit 40, and is composed of a sawtooth wave having a period set to, for example, 200 msec. Further, the fixed oscillation circuit 42 also includes a circuit that oscillates an oscillation signal Cosc composed of a sawtooth wave having a frequency higher than that of the reference oscillation signal Ctim.

The selection circuit 43 selects the first switching signal or the second switching signal based on the potential of the VFB terminal, that is, the output voltage VDC of the power factor improving circuit 20, and outputs the first switching signal or the second switching signal from the terminal GD. The switching signal output from this terminal GD is supplied to the gate of the switching element Q21 of the power factor improving circuit 20.

That is, the self-excited oscillation circuit 41, the fixed oscillation circuit 42, and the selection circuit 43 constitute a PFC control circuit that controls the power factor improvement circuit 20. Since the control of the power factor improving circuit 20 by the PFC control circuit and the operation of the power factor improving circuit 20 by this control are well known, the description thereof is omitted here.

The lighting control circuit 44 generates a gate signal for turning on / off the switching element Q31 based on the potentials of the VS terminal and the VB terminal, respectively. Further, the lighting control circuit 44 determines the frequency and duty ratio of the gate signal by the differential amplification voltage OPout output from the operational amplifier 47. Then, the lighting control circuit 44 outputs the gate signal from the HO terminal and supplies it to the base terminal of the switching element Q31. As a result, the switching element Q31 operates on / off, and the step-down chopper circuit 30 operates. Since the control of the step-down chopper circuit 30 by the lighting control circuit 44 and the operation of the step-down chopper circuit 30 by the control are well known, the description thereof is omitted here.

The power supply circuit 46 generates a circuit operating voltage Vcc or the like from a high-voltage full-wave rectified voltage taken in via a VDC terminal prior to starting the control circuit 40 by a dropper method. Then, the power supply circuit 46 applies the circuit operating voltage Vcc to the Vcc terminal. Further, the power supply circuit 46 appropriately applies a dropper voltage including the circuit operating voltage Vcc to other circuits.

In the operational amplifier 47, the non-inverting input terminal (positive electrode terminal +) is connected to the OP + terminal, and the inverting input terminal (negative electrode terminal-) is connected to the OP- terminal. Then, the differential amplification voltage OPout having a magnitude corresponding to the difference between the potential of the OP- terminal and the potential of the OP + terminal is output to the lighting control circuit 44 and the monitoring circuit 48. As described above, the lighting control circuit 44 adjusts the switching frequency and duty ratio of the switching element Q31 of the step-down chopper circuit 30 according to the differential amplification voltage OPout from the operational amplifier 47. In this adjustment, the output current of the step-down chopper circuit 30 is feedback-controlled so that the load current value corresponding to the potential of the OP-terminal matches the target current value corresponding to the potential of the OP + terminal. Here, the operational amplifier 47 functions as an error amplifier. Further, since the light emitting diode has a constant voltage characteristic, the output voltage is increased or decreased by controlling the output current.

The monitoring circuit 48 is connected to the LED D11 of the light source unit 1 based on the differential amplification voltage OPout output from the operational amplifier 47, the potential of the ABN terminal, and the detection signal input from the mounting detection circuit 50 via the Lamp terminal. It is determined that the decrease in the flowing current is abnormal, the voltage applied to the light source unit 1 is abnormal, and whether or not the light source unit 1 is attached is determined. Then, when it is determined to be abnormal, an abnormality detection signal is output to the protection circuit 45.

Further, the monitoring circuit 48 receives a temperature detection signal from a temperature sensor (not shown) installed for detecting the temperature of the control circuit 40 including the integrated circuit, and when the detected temperature exceeds the threshold value, the protection circuit 45 receives the temperature detection signal. On the other hand, a temperature abnormality detection signal is output.

The protection circuit 45 usually connects the VDC terminal to the power supply circuit 46. Further, the protection circuit 45 monitors the current flowing through the step-down chopper circuit 30 from the potential of the OCP terminal. When the abnormality of the overcurrent is detected, the connection between the VDC terminal and the power supply circuit 46 is cut off, and the operations of the self-excited oscillation circuit 41 and the lighting control circuit 44 of the PFC control circuit are latched and stopped.

Further, when the protection circuit 45 receives the abnormality detection signal indicating the decrease abnormality of the current supplied to the LED 11 from the monitoring circuit 48, the protection circuit 45 resets the operations of the lighting control circuit 44 and the self-excited oscillation circuit 41, and also causes the sequence control circuit 49. On the other hand, the reset signal RS is output.

Further, when the protection circuit 45 receives the temperature abnormality detection signal from the monitoring circuit 48, the protection circuit 45 cuts off the connection between the VDC terminal and the power supply circuit 46, and latches and stops the operations of the self-excited oscillation circuit 41 and the lighting control circuit 44 of the PFC control circuit. Let me.

The sequence control circuit 49 activates each circuit in the control circuit 40 according to a predetermined activation sequence when a power switch (not shown) is turned on or when a reset signal RS is received from the protection circuit 45, whereby the power supply is supplied. The device 2 starts supplying the output voltage and the output current to the light source unit 1. The above activation sequence will be described in detail later.

(motion)
Next, the operation of the power supply device 2 configured as described above will be described.
(1) Start-up sequence When the power switch is turned on, the power supply device 2 starts up as follows under the control of the sequence control circuit 49 of the control circuit 40. FIG. 3 is a diagram showing the activation sequence.

When the operating voltage VST is supplied to the VC2 terminal of the control circuit 40 by turning on the power switch (not shown), the C timer of the fixed oscillation circuit 42 starts oscillating the reference oscillation signal Ctim. As shown in FIG. 3, the reference oscillation signal Ctim is composed of a sawtooth wave in which the rising waveform and the falling waveform are symmetrical, and the period is set to, for example, 200 msec.

The sequence control circuit 49 is connected to the monitoring circuit 48 during the period from the start of oscillation of the reference oscillation signal Ctim to the detection of the second valley of the reference oscillation signal Ctim (the period up to time t1 = 400 msec). On the other hand, a mask signal MS is given, thereby prohibiting (masking) the mounting detection operation of the light source unit 1.

When the mounting detection operation prohibition period ends, it is determined in the monitoring circuit 48 whether or not the light source unit 1 is mounted based on the potential input from the mounting detection circuit 50 to the Lamp terminal. Then, when it is confirmed that the light source unit 1 is mounted, the operating voltage Vcc generated from the power supply circuit 46 rises, and the Vref increases accordingly. Then, when the Vref reaches the specified value, the initial charging between VB and VS is started from the time t2. That is, the discharge circuit of the VB-VS is turned on. Further, when the first valley of the reference oscillation signal Ctim is detected after reaching the specified value of Vref, the supply of the mask signal MS from the sequence control circuit 49 to the selection circuit 43 is turned off, and the power factor improvement circuit 20 Starts working.

Next, after the operating voltages Vcc and Vref reach the specified values, the output voltage of the power factor improving circuit 20 reaches 90% of the rated value at time t3 when the second valley of the reference oscillation signal Ctim is detected. Whether or not it has been done is determined based on the potential input to the VFB terminal. When it is confirmed by this determination that the output voltage of the power factor improving circuit 20 has reached 90% of the rated value, at that time t3, as shown in FIG. 3, the charging gradient of the reference oscillation signal Ctim voltage is made gentle. At the same time as the soft start operation is started, the oscillation signal Cosc, which has a shorter period than the reference oscillation signal Ctim, is started to oscillate.

Further, at the time t3, the sequence control circuit 49 turns off the supply of the mask signal MS to the monitoring circuit 48. As a result, the detection operation of the potential input to each terminal of ABN and OCP is started. The soft start operation is an operation in which the potential of the reference oscillation signal is gradually increased over a period longer than the period of the reference oscillation signal Ctim.

When the soft start operation is started and the timing t4 at which the voltage value of the oscillation signal Cosc first falls below the voltage value of the reference oscillation signal Ctim of the C timer is detected, the VB-VS discharge circuit is turned off at this point t4. Become. Further, at the time t4, the control for masking the output of the operational amplifier 47 is stopped, the differential amplification voltage OPout output from the operational amplifier 47 is input to the lighting control circuit 44, and the operation of the step-down chopper circuit 30 is started. As a result, during the soft start operation period, the lamp current IF supplied from the step-down chopper circuit 30 to the light source unit 1 gradually increases as shown in FIG.

If the output voltage of the power factor improving circuit 20 does not reach 90% of the rated value at the above time t3, after the output voltage reaches 90% of the rated value, the valley of the reference oscillation signal Ctim is set. The soft start operation is started from the time of detection. However, if the output voltage does not reach 90% of the rated value within the period from the time t3 to counting four valleys of the reference oscillation signal Ctim, the soft start operation is not started and the power supply device 2 is started. Is stopped (latch stop).

When the soft start operation period ends at time t5, the threshold initial setting period is set in the monitoring circuit 48 from the end time t5 to the time t6 when the potential of the reference oscillation signal Ctim drops to the valley. Then, a threshold value for deterioration detection is set during this threshold value initial setting period. At this time, as the initial value of the threshold value, for example, a voltage value stored in advance in the memory in the monitoring circuit 48 is used.

In the threshold setting operation, the protection voltage ΔV is added to the detection potential of the lamp voltage, and the addition is larger than the voltage value after the addition from among a plurality of candidate thresholds set in advance within the range of normal operation. The candidate threshold value closest to the later voltage value may be selected and set as the threshold value.

(2) Protective operation after the start of lighting When the power supply device 2 is activated and the light source unit 1 is started to be lit, the detection potential corresponding to the load current (lamp current) IF supplied to the light source unit 1 is the operational amplifier 47. Is input to OP-, and the difference amplification voltage OPout between the detected potential and the target value is output from the operational amplifier 47. This differential amplification voltage OPout is input to the lighting control circuit 44, and the lighting control circuit 44 is a step-down chopper circuit for reducing the differential amplification voltage OPout, that is, for matching the lamp current IF flowing through the light source unit 1 with the target current value. 30 is controlled. Thus, the lamp current IF is controlled to a constant current.

(2-1) When the light source unit 1 is removed or dropped, or the signal line is disconnected It is assumed that, for example, the light source unit 1 is removed or dropped, or the signal line is broken in a steady state. In this case, the power supply device 2 performs the following protection operation under the control of the control circuit 40. FIG. 4 is a diagram showing an example of the operation.

That is, when the light source unit 1 is removed or dropped, or the signal line is disconnected, the lamp current IF flowing through the light source unit 1 becomes zero, and the OP-potential of the operational amplifier 47 also becomes zero. Therefore, the differential amplification voltage OPout output from the operational amplifier 47 becomes the maximum value as shown in FIG. 4, and this value is maintained thereafter. Then, when the state in which the differential amplification voltage OPout reaches the maximum value continues Tout for a preset time, the monitoring circuit 48 outputs an abnormality detection signal indicating a decrease abnormality of the lamp current IF, and receives this abnormality detection signal. The reset signal RS is output from the protection circuit 45.

When the reset signal RS is output, the sequence control circuit 49 resets the operating state of the power supply device 2, and then restarts the power supply device 2 according to the start-up sequence as shown in FIG. At this time, if the light source unit 1 is reattached or the signal line is connected, the lamp current IF flows through the light source unit 1 as shown by the alternate long and short dash line in FIG. 4 after restarting.

However, if the light source unit 1 is not mounted or the signal line is still disconnected, the lamp current IF is maintained at zero, so that the differential amplification voltage OPout of the operational amplifier 47 becomes the maximum value again. .. Then, when this state continues to Tout for the predetermined time, an abnormality detection signal indicating a decrease abnormality of the lamp current IF is output from the monitoring circuit 48 as described above, and a reset signal RS is output from the protection circuit 45 in response to this abnormality detection signal. It is output. Then, under the control of the sequence control circuit 49, the power supply device 2 is restarted. After that, the restart described above is repeated.

On the other hand, in the monitoring circuit 48, the temperature of the control circuit 40 is monitored based on the detected value of the temperature sensor (not shown). Then, the repetition of the restart continues for, for example, about 30 seconds, and when the temperature of the control circuit 40 rises and the temperature detection value reaches the threshold value, the monitoring circuit 48 outputs a temperature abnormality detection signal. When this temperature abnormality detection signal is received, the protection circuit 45 cuts off the connection between the VDC terminal and the power supply circuit 46, and the self-excited oscillation circuit 41 and the lighting control circuit 44 that perform PFC control are stopped. That is, the power supply device 2 is latched and stopped as shown in FIG. Therefore, the power supply device 2 is protected before it fails.

(2-2) When the power supply voltage drops temporarily The decrease in the lamp current IF flowing through the light source unit 1 can also occur due to a temporary power failure or drop in the power supply voltage. Also in this case, when the lamp current IF becomes almost zero, the differential amplification voltage OPout of the operational amplifier 47 becomes the maximum value as shown in FIG. Then, when this state continues to Tout for the predetermined time, an abnormality detection signal indicating a decrease abnormality of the lamp current IF is output from the monitoring circuit 48 as described above, and a reset signal is received from the protection circuit 45 in response to this abnormality detection signal. RS is output. Then, the power supply device 2 is restarted under the control of the sequence control circuit 49.

On the other hand, when the power supply voltage is restored from a temporary power failure or decrease during this restart period, the lamp current IF flowing through the light source unit 1 is also restored as shown in FIG. Therefore, after the restart, the lamp current IF returns to the normal value, and the differential amplification voltage OPout of the operational amplifier 47 does not reach the maximum value and maintains the value in the constant current control. That is, the power supply device 2 is not latched and stopped. Therefore, it is not necessary for the user to turn on the power switch again.

(effect)
As described in detail above, in one embodiment, the state in which the lamp current IF supplied to the light source unit 1 decreases as it becomes zero and the differential amplification voltage OPout output from the operational amplifier 47 reaches the maximum value is Tout for a predetermined time. When continuous, the protection circuit 45 outputs a reset signal RS, and as a result, the power supply device 2 is autonomously restarted under the control of the sequence control circuit 49. Then, when the restart is repeated and the temperature of the control circuit 40 reaches the threshold value, the latch is stopped. On the other hand, if the lamp current IF returns to the target value in the period until the temperature of the control circuit 40 reaches the threshold value, the repetition of the restart ends at that point, and the light source unit 1 continues the lighting operation.

Therefore, if the cause of the decrease in the supply current to the light source unit 1 is a temporary power failure or decrease in the power supply voltage, the lighting operation of the light source unit 1 can be restored without turning on the power switch again. it can. On the other hand, if the cause of the decrease in the lamp current IF of the light source unit 1 is permanent such as the removal or disconnection of the light source unit 1 or the disconnection of the signal line, the restart is repeated and the temperature of the control circuit 40 is increased. Latch is stopped when the threshold is reached. Therefore, it is possible to reliably protect the power supply device 2 before it causes a failure.

Further, after the abnormality detection signal is output from the monitoring circuit 48 and the power supply device 2 is reset by the protection circuit 45, the switch between the DIS terminal and the GND may be controlled to be turned on. For example, when the light source unit 1 is removed from the power supply device 2, the output terminal of the power supply device 2 is opened, and the output voltage rises until the protection circuit 45 resets the operation of the lighting control circuit 44 and the self-excited oscillation circuit 41. Along with this, the voltage of the capacitor C31 also rises. However, when the switch between the DIS terminal and GND is controlled to be turned on, the potential of the DIS terminal becomes the ground potential, the potential of the connection point between the inductor L31 of the step-down chopper circuit 30 and the capacitor C31 is drawn to the ground potential, and the capacitor C31. Since the electric charge charged in is momentarily zero, the inrush current does not flow to the light source unit 1 side even if the light source unit 1 is reattached. Therefore, there is no possibility that the light emitting diode D11 of the light source unit 1 will fail due to the inrush current.

[Other Embodiments]
In the above embodiment, the power supply device 2 is latched and stopped when the temperature of the control circuit 40 reaches the threshold value in a state where the restart is repeated. However, the present invention is not limited to this, and for example, the number of repetitions of the restart is counted, or the length of the period during which the restart is repeated is timed, and the number of repetitions reaches a predetermined value or is restarted. The power supply device 2 may be latched and stopped when the length of the repeated start-up period reaches a predetermined time. By doing so, it is possible to eliminate the need for the temperature sensor for detecting the temperature of the control circuit 40 and the temperature monitoring circuit in the monitoring circuit 48, thereby reducing the number of parts, reducing the size of the device, and reducing the price. It can be realized.

In addition, the configurations of the power supply device 2 and the control circuit 40, the type and configuration of the light source unit 1, the activation sequence, and the like can be variously modified and implemented without departing from the gist of the present invention.

Although some embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Light source unit, 2 ... Power supply device 20 ... Rectifier circuit, 20 ... Power factor improvement circuit, 30 ... Step-down chopper circuit, 40 ... Control circuit, 41 ... Self-excited oscillation circuit, 42 ... Fixed oscillation circuit, 43 ... Selection circuit, 44 ... lighting control circuit, 45 ... protection circuit, 46 ... power supply circuit, 47 ... operational amplifier, 48 ... monitoring circuit, 49 ... sequence control circuit, 50 ... mounting detection circuit.

Claims (3)

With a voltage-current generation circuit that generates a variable output voltage and output current and supplies it to the light source unit;
With a sequence control circuit that activates the voltage / current generation circuit in a predetermined procedure in response to a power-on operation or a reset operation for the voltage / current generation circuit;
The value of the output current supplied to the light source unit from the voltage / current generation circuit after being activated by the sequence control circuit is detected, and the difference between the detected value of the output current and a preset target value. With a comparison circuit that outputs the differential amplification voltage that amplified the
With an output control circuit that controls to reduce the differential amplification voltage output from the comparison circuit;
With a protection circuit that operates to protect the voltage / current generation circuit based on the differential amplification voltage output from the comparison circuit;
Equipped with
The protection circuit
A reset unit that causes the voltage / current generation circuit to perform the reset operation when the differential amplification voltage output from the comparison circuit reaches a preset upper limit value continuously for a predetermined time.
By the reset operation is repeated a plurality of times, when the temperature of the control circuit including the sequence control circuit and the protection circuit exceeds a value corresponding to the normal range, to stop the power supply to the voltage-current generating circuit In other cases, with a protection control unit that maintains the operating state of the voltage / current generation circuit;
Power supply with. The power supply device according to claim 1, wherein the protection control unit stops power supply to the voltage / current generation circuit when the number of repetitions or the repetition duration of the reset operation exceeds a value corresponding to the normal range. With the power supply device according to claim 1 or 2 .
With a light source unit that is connected to the power supply terminal of the power supply device and whose lighting is controlled;
Lighting device equipped with.