JP6817078B2 - 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 a light emitting diode (LED: Light Emitting Diode) as a light source, and a lighting device including the power supply device.

In a power supply device used in a lighting fixture that uses an LED as a light source, when the LED light source unit is turned on, for example, the voltage applied to the LED (output voltage) and the current flowing through the LED (output current) are detected. However, constant current control is performed to adjust the output current so that the output current matches the rated current of the LED, for example. Therefore, if, for example, the LED light source unit is removed from the socket or the output power supply line to the LED is disconnected during lighting, the current flowing through the LED instantly becomes zero immediately after that, so that the power supply device has a power supply device. The voltage supplied to the LED is boosted to a voltage higher than the steady-state voltage, which causes a failure and is not preferable.

Therefore, the power supply device has a function of presetting a threshold value for monitoring the voltage supplied to the LED, and when the supplied voltage exceeds the threshold value, it is determined that an abnormal voltage has occurred and the lighting circuit is stopped. Is provided. Recently, a power supply device shared by a plurality of types of LED light source units having different rated voltages has been developed, and such a power supply device is provided with a function of setting a different threshold value for each rated voltage of the LED light source unit. (See, for example, Patent Document 1).

Japanese Patent No. 5525393

However, the power supply device described in Patent Document 1 sets a threshold value for determining an abnormal voltage for each lighting voltage of the LED light source unit at the time of starting when the LED light source unit is lit. I try to maintain this threshold. Therefore, for example, when the voltage supplied to the LED light source unit changes due to the influence of the temperature rise of the LED light source unit or the power supply unit itself, even if the change is within the normal range, the supply voltage value after the change is used. It was judged as an abnormal voltage, and the lighting operation sometimes stopped.

An embodiment of the present invention has been made by paying attention to the above circumstances, and is a power supply device that does not erroneously determine this as an abnormal voltage even if the supply voltage level to the light source unit changes within a normal range during lighting. And an attempt to provide a lighting device equipped with this power supply.

The power supply device according to the embodiment has 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 a value of the output current supplied from the voltage-current generation circuit to the light source unit. With an output control circuit that detects and controls the voltage / current generation circuit to increase or decrease the output voltage so that the value of the detected output current matches a preset target value;
With an output voltage detection circuit that detects the output voltage supplied from the voltage-current generation circuit to the light source unit; the output voltage is normal by comparing the output voltage detected by the output voltage detection circuit with a threshold value. It includes an output voltage determination circuit that determines whether or not it is within the range; and a threshold setting circuit that sets a threshold used by the output voltage determination circuit; the threshold setting circuit activates the voltage-current generation circuit. In a predetermined period after the start-up sequence for the above is completed, the voltage value obtained by adding the predetermined protection voltage to the output voltage detected by the output voltage detection circuit is exceeded, and the preset voltage / current generation circuit is normal. The candidate threshold closest to the voltage value is selected from the plurality of candidate thresholds of the output voltage when it is assumed to be operating, and the voltage value of the selected candidate threshold is set as the initial value of the threshold. It is provided with an initial setting unit and;

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, even if the output voltage supplied to the light source unit during the lighting operation changes within a normal range, a power supply device that does not erroneously determine this as an abnormal voltage and a lighting device provided with this power supply device are provided. 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 signal waveform diagram which shows the protection voltage update operation by the control circuit shown in FIG. FIG. 6 is an enlarged view showing a part of the signal waveform diagram shown in FIG.

Hereinafter, embodiments will be described with reference to the drawings.
[One Embodiment]
(Constitution)
FIG. 1 is an electric 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 be provided with another type of 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 supply 200 such as a commercial power supply 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). The switching element Q21 connects the drain terminal to the connection point between the output end of the coil L21 and the anode of the diode D21, connects the source terminal to one end of the resistor R21 and the CS terminal of the control circuit 40, and connects the gate terminal. 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 it 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 a current flowing through the switching element Q21, a 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 is also connected to 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 drover 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 R31. 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 resistor R9. The potential of the OP-terminal depends on the current flowing through the combined resistance of the resistors R11, R31, and R32. 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 when the light source unit 1 which is a load is attached to the power supply device 2. is there. 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. Due to 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 to suppress the discharge current of the capacitor C31 and to 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. Further, the capacitors C6 and C7 and the resistor 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 block diagram showing the main configuration thereof.
That is, the control circuit 40 includes a self-excited oscillation circuit 41, a fixed oscillation circuit 42, a selection circuit 43, a lighting control circuit 44, a protection circuit 45, a power supply circuit 46, an operational amplifier 47, a monitoring circuit 48, and the like. It includes a sequence control circuit 49. 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. The control circuit 40 may include at least a part of each of the circuits 41 to 49 as a digital circuit, and at least a part of the processing performed by each of the circuits 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 whose period is set to, for example, 200 msec. Further, the fixed oscillation circuit 42 also includes a circuit that oscillates an oscillation signal Cosc 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 force factor improving circuit 20 by the PFC control circuit and the operation of the force 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 voltage signal OPout output from the operational amplifier 47. Then, the lighting control circuit 44 outputs a gate signal from the HO terminal and supplies it to the base terminal of the switching element Q31, thereby turning on / off the switching element Q31 to control the operation of the step-down chopper circuit 30. 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 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 a current abnormality such as an overcurrent is detected, the protection circuit 45 cuts off the connection between the VDC terminal and the power supply circuit 46, and stops the operation of the self-excited oscillation circuit 41 and the lighting control circuit 42 of the PFC control circuit. Further, the protection circuit 45 receives an abnormal signal from the monitoring circuit 48. Then, even when an abnormal signal is received, the protection circuit 45 cuts off the connection between the VDC terminal and the power supply circuit 46, and stops the operation of the self-excited oscillation circuit 41 and the lighting control circuit 42 of the PFC control circuit.

The power supply circuit 46 generates a circuit operating voltage Vcc or the like by a dropper method from a high voltage full-wave rectified voltage taken in via a VDC terminal prior to starting the control circuit 40. 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, a voltage signal 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 voltage signal 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 includes a monitoring circuit main body 481 and a threshold value setting circuit 482. The monitoring circuit main body 481 is a current flowing through the LED 11 of the light source unit 1 based on the 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. The abnormality of the above, the abnormality of the voltage applied to the light source unit 1, and the presence / absence of mounting of the light source unit 1 are determined, respectively. Then, when it is determined to be abnormal, an abnormality detection signal is output to the protection circuit 45.

The threshold value setting circuit 482 has a threshold value setting period set immediately after the start sequence ends based on the mask signal MS output from the sequence control circuit 49 and the reference oscillation signal Ctim generated from the C timer of the fixed oscillation circuit 42. In addition, the initial value of the threshold value is set in the monitoring circuit main body 481. The initial value of the threshold value is set to, for example, a voltage value stored in advance in the memory in the threshold value setting circuit 482.

Further, the threshold value setting circuit 482 periodically updates the threshold value in the setting during the lighting operation of the light source unit 1 after the initial setting of the threshold value. The update of the threshold value is performed based on the potential of the ABN terminal and the protection voltage ΔV, and the specific operation thereof will be described in detail later.

When the abnormality detection signal is output from the monitoring circuit 48, the protection circuit 45 stops the operation of the self-excited oscillation circuit 41 and the lighting control circuit 44, and gives a reset signal RS to the sequence control circuit 49.

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 a reset operation is performed, whereby the light source from the power supply device 2 The supply of the output voltage and the output current to the unit 1 is started. The above activation sequence will also 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, 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 to prohibit (mask) the mounting detection operation of the light source unit 1.

When the mounting detection operation prohibition period ends, the monitoring circuit 48 determines 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, at t3 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 operation.

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 this is done is determined based on the potential input to the VFB terminal. As a result of this determination, when it is confirmed 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 gentle. Then, the soft start operation is started, and 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 gradually increases 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 output OPout of 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 period, the output 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).

(2) Initial setting of threshold value When the soft start operation period ends at time t5, in the threshold value setting circuit 482 of the monitoring circuit 48, the period from the end time t5 to the time t6 when the potential of the reference oscillation signal Ctim drops to a valley. The threshold initial setting period is set in. Then, during this threshold value initial setting period, a threshold value for deterioration detection is initially set for the monitoring circuit main body 481. At this time, as the initial value of the threshold value, the voltage value stored in advance in the memory in the threshold value setting circuit 482 is used.

(3) Updating the threshold value during lighting In the threshold value setting circuit 482, the threshold value updating operation is performed as follows during the lighting operation of the light source unit 1 after the initial setting of the threshold value. 4 and 5 show an example of the update operation.

That is, as shown in FIG. 4A, the threshold value setting circuit 482 first detects a peak of the reference oscillation signal Ctim oscillated from the C timer of the fixed oscillation circuit 42. Then, at each timing of the detected peaks, the detection potential corresponding to the output voltage (lamp voltage) of the step-down chopper circuit 30 input via the ABN terminal is detected as shown in FIG. 4 (b).

Subsequently, the threshold value setting circuit 482 calculates a potential (shown by a broken line in FIG. 5) by adding a predetermined protection voltage ΔV to the detection potential as shown in FIG. Further, at this time, the threshold value setting circuit 482 stores a plurality of candidate threshold values set in advance within the range of the lamp voltage assumed to be normal operation in the memory. For example, FIG. 5 shows a case where eight candidate thresholds Vth1 to Vth8 are set at equal intervals. Then, the threshold value setting circuit 482 selects the candidate threshold value closest to the calculated potential from the candidate threshold values larger than the calculated potential, that is, the potential obtained by adding the protection voltage ΔV to the detected potential. For example, in the example of FIG. 5, the candidate threshold value Vth6 is selected.

Further, as shown in FIG. 4A, the threshold value setting circuit 482 detects a valley following the detected peak of the reference oscillation signal Ctim. Then, at the timing of the detected valley, the candidate threshold value Vth6 set based on the lamp voltage detected at the timing of the peak immediately before the detected valley is output to the monitoring circuit main body 481, and the threshold value set up to that point is output. Update to the candidate threshold value Vth6.

Thus, the threshold value Vth for deterioration detection is periodically updated based on the lamp voltage at each time in synchronization with the reference oscillation signal Ctim after the start of the lighting operation of the light source unit 1.

(effect)
As described in detail above, in one embodiment, the monitoring circuit 48 is provided with the threshold value setting circuit 482, and the threshold value setting circuit 482 performs the following threshold value setting operation. That is, first, the initial value of the threshold value is set in the threshold value setting period set immediately after the end of the activation sequence. Next, during the lighting operation of the light source unit 1 after the initial setting of the above threshold value, the lamp voltage was detected at the timing of the peak of the reference oscillation signal Ctim oscillated from the C timer, and the protection voltage ΔV was added to this detected potential. The potential is calculated, and the candidate threshold value closest to the calculated potential is selected from the candidate threshold values larger than the calculated potential. Then, the valley following the peak of the reference oscillation signal Ctim oscillated from the C timer is detected, and at the timing of this detected valley, the above is set based on the lamp voltage detected at the timing of the peak immediately before that. The threshold value that has been set up to that point is updated to the candidate threshold value.

Therefore, when the lamp voltage supplied from the step-down chopper circuit 30 to the light source unit 1 increases due to the influence of the temperature characteristics of the light source unit 1 or the power supply device 2, for example, during the lighting operation of the light source unit 1, the lamp voltage is detected. When the potential exceeds the threshold value, the monitoring circuit 48 outputs an abnormality detection signal, and the protection circuit 45 stops the operation of the power supply device 2. Therefore, it is possible to protect the light source unit 1 from abnormal operation due to the influence of the temperature characteristics of the light source unit 1 or the power supply device 2.

In addition, since the lamp voltage is detected and the threshold value is updated alternately every other cycle of the reference oscillation signal Ctim, for example, when the detected lamp voltage temporarily increases due to the influence of noise or the like, this is temporary. The threshold value corresponding to the increased detection value is updated one cycle later than the detection timing of the lamp voltage. Therefore, during the period from the detection timing of the lamp voltage to the update of the threshold value, the appropriate threshold value before the update is maintained, and if an abnormality of the lamp voltage occurs during this period, the abnormality is concerned. Can be detected immediately.

Further, after the abnormality detection signal is output from the monitoring circuit 48 and the operation of the power supply device 2 is stopped by the protection circuit 45, the switch between the DIS terminal and the GND may be controlled to be turned on. For example, if the light source unit 1 is removed from the power supply device 2 while constant current control is being performed, the output voltage of the power supply device 2 is opened until the protection circuit 45 stops the operation of the lighting control circuit 42. As the voltage rises, the voltage of the capacitor C31 also rises accordingly. 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.

Further, when updating the threshold value, a plurality of candidate threshold values are prepared in advance, and the candidate threshold value larger and closest to the voltage value obtained by adding the protection voltage ΔV to the detection potential of the lamp voltage is selected to select the threshold value being set. Is updated to the above-selected threshold value. Therefore, it is possible to set an appropriate threshold value according to the detected value of the lamp voltage at each time within the range of the lamp voltage assumed to be normal operation.

[Other Embodiments]
In the above embodiment, the threshold value setting period is set immediately after the end of the activation sequence to initialize the threshold value, but the threshold value initial setting period is set in the period immediately before the end of the activation sequence to initialize the threshold value. You may. Further, in one embodiment, a predetermined threshold value is initially set in the threshold value initial setting period. However, not limited to this, as in the case of the above-mentioned update, the protection voltage ΔV is added to the detection potential of the lamp voltage at that time, and after the above addition from a plurality of candidate threshold values set in advance within the range of normal operation. A candidate threshold value that is larger than the voltage value of and closest to the voltage value after the addition may be selected and initially set.

Further, in the above-described embodiment, the lamp voltage is detected and the threshold value is updated every other cycle of the reference oscillation signal Ctim output from the C timer during the threshold value update period, but the lamp voltage is updated every plurality of cycles. May be detected and the threshold value may be updated.

In addition, the configurations of the power supply device 2 and the control circuit 40, the type and configuration of the light source unit, 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, 10 ... 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, 481 ... monitoring circuit body, 482 ... threshold setting circuit.

Claims (4)

With a voltage-current generation circuit that generates a variable output voltage and output current and supplies it to the light source unit;
The voltage / current generation circuit is controlled to detect the value of the output current supplied from the voltage / current generation circuit to the light source unit and to match the detected output current value with a preset target value. With an output control circuit that increases or decreases the output voltage;
With an output voltage detection circuit that detects the output voltage supplied from the voltage / current generation circuit to the light source unit;
With an output voltage determination circuit that determines whether or not the output voltage is within a normal range by comparing the output voltage detected by the output voltage detection circuit with a threshold value;
With a threshold setting circuit that sets the threshold value used by the output voltage determination circuit;
Equipped with;
The threshold setting circuit is
In a predetermined period after the start sequence for starting the voltage / current generation circuit is completed, the voltage value obtained by adding a predetermined protection voltage to the output voltage detected by the output voltage detection circuit is exceeded and set in advance. The candidate threshold closest to the voltage value is selected from the plurality of candidate thresholds of the output voltage when the voltage / current generation circuit is assumed to be operating normally, and the voltage value of the selected candidate threshold is selected. With the initial setting unit that sets as the initial value of the threshold value;
Power supply with. The output voltage detected by the output voltage detection circuit at the first timing is captured in synchronization with the timing signal that alternately generates the first timing and the second timing at regular time intervals;
At the second timing, the threshold value is updated to a value generated based on the output voltage taken in at the first timing and the protection voltage;
The power supply device according to claim 1, further comprising an update unit of the threshold value setting circuit . Update portion of the front Ki閾value setting circuit,
A plurality of candidate threshold values are set within the range of the output voltage when the voltage / current generation circuit is assumed to be operating normally;
The candidate threshold value closest to the voltage value is selected from the candidate threshold values exceeding the voltage value obtained by adding the protection voltage to the output voltage detected by the output voltage detection circuit;
Update the threshold being set to the selected candidate threshold;
The power supply device according to claim 1 or 2. With the power supply device according to any one of claims 1 to 3.
With a light source unit that is connected to the power supply terminal of the power supply device and is controlled to be lit;
Lighting device equipped with.