JP5425124B2 - Power supply device and lighting device - Google Patents

Description

  The present invention relates to a power supply device (power supply circuit) and a lighting device using the same.

  A power source that converts electric power supplied from an AC power source such as a commercial power source into direct current for lighting a light emitting element such as a light emitting diode (hereinafter referred to as “LED”) or organic electroluminescence (hereinafter referred to as “organic EL”). In a circuit, a configuration in which a power factor correction circuit (PFC circuit) and a power conversion circuit are combined is known (see, for example, Patent Documents 1 and 2).

JP 2009-80983 A JP 2010-1113924 A

  The power factor correction circuit is a circuit for bringing the input power factor close to 1 in order to suppress power source distortion or the like of the commercial power source. For example, a boost converter circuit or the like is used. The power conversion circuit is a constant current driving circuit that operates so as to maintain a current flowing through the light emitting element at a predetermined target value by adjusting a voltage applied to the light emitting element. For example, the flyback converter circuit or DC (direct current) / DC A system such as a converter circuit or a half bridge circuit is used. Usually, since the load voltage for driving light emitting elements such as LED and organic EL is lower than the output voltage output from the power factor correction circuit, the power conversion circuit has a step-down circuit that outputs a voltage lower than the input voltage. Is used.

  Since there are various types of power supply voltages for commercial power supplies, it is desirable that the power supply circuit be compatible with AC power supplies in a wide voltage range. Further, a harmonic circuit and a high power factor are required for a power supply circuit of a lighting fixture that is not small and consumes a certain amount of power. Therefore, the power supply circuit of the lighting fixture has a configuration in which a power factor correction circuit and a power conversion circuit are combined.

  When a current is passed through the LED, the forward voltage generated at both ends of the LED varies depending on manufacturing variations, ambient temperature, heat generation due to its own loss, and the amount of current flowing. Therefore, in consideration of the above variations and temperature changes, it is desirable to drive the LED at a constant current in order to stably obtain a desired light output in a lighting fixture using the LED.

  However, in the past, a power supply circuit that performs constant current driving is a power supply circuit that always supplies a constant current to a light emitting element (LED, organic EL, etc.) to be connected in order to stably obtain a desired light emission output. The resistance value and the reference voltage are designed. Therefore, when the configuration of the LED series circuit to be connected (number of LEDs, characteristics, etc.) is different, even if the desired light emission output is the same, if the constant current value flowing through the LED series circuit is different, There is a problem in that it is necessary to redesign the power supply circuit, and the same power supply circuit cannot be used as a drive circuit for an LED series circuit that requires different constant current values. In other words, a power supply circuit that performs constant current driving has been conventionally designed in accordance with a light emitting element to be connected, and therefore has a problem that it cannot be used for another light emitting element that requires a different constant current value.

  Conventionally, a power supply circuit that performs constant current driving can continue to drive the remaining light emitting elements at a constant current even when a plurality of light emitting elements connected in series, for example, has a short circuit failure. When one of them has an open failure, the current cannot be detected, so that there is a problem that the maximum voltage that can be output by the power conversion circuit is applied to both ends of the light emitting element (for example, LED series circuit).

  For example, the present invention automatically determines which light emitting element group is connected among at least two types of light emitting element groups (LED series circuit, etc.) with one power supply circuit, and the light emitting element group is necessary. The light emitting element group is driven with a constant current value as follows. In addition, for example, when at least one light emitting element of the light emitting element group has an open failure, the object is to automatically detect that and stop driving the light emitting element group.

A power supply device according to one aspect of the present invention includes:
A constant current power supply unit connected to the light emitting element group connected in series and outputting a constant current to the light emitting element group to light the light emitting element group;
A storage unit that stores in advance a correspondence relationship between the configuration of the light emitting element group, the dimming degree of the light emitting element group, and the current value of the constant current output from the constant current power supply unit;
A voltage detection unit for detecting a voltage applied to the light emitting element group from the constant current power supply unit;
A determination unit that determines the configuration of the light emitting element group based on the voltage detected by the voltage detection unit in a state where a constant current of a predetermined current value is output from the constant current power supply unit;
Connected to a dimmer that commands the dimming degree of the light emitting element group, and from the storage unit, a current value corresponding to a combination of the configuration determined by the determining unit and the dimming degree commanded from the dimmer And a control unit that causes the constant current power supply unit to output a constant current of the read current value.

  According to one aspect of the present invention, a single power supply circuit automatically determines which light-emitting element group is connected among at least two types of light-emitting element groups (such as an LED series circuit), and emits the light. The light emitting element group can be driven with a constant current value required by the element group.

FIG. 3 is a circuit block diagram illustrating an example of the overall configuration of the lighting apparatus according to Embodiment 1; FIG. 3 is a circuit diagram illustrating an example of a specific circuit configuration of the lighting device according to Embodiment 1; 1 is a block diagram illustrating a configuration of a microcomputer (microcomputer) according to Embodiment 1. FIG. 3 is a graph showing the relationship between the voltage and current value of the LED series circuit according to Embodiment 1. 3 is a graph showing a voltage change after power-on of the LED series circuit according to the first embodiment. The graph which shows the voltage change at the time of the open circuit failure of the LED series circuit which concerns on Embodiment 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a circuit block diagram showing an example of the overall configuration of lighting apparatus 800 according to the present embodiment.

  In FIG. 1, a commercial power source 101 and a dimmer 103 are connected to the lighting device 800. The lighting device 800 includes a power supply circuit 100 (an example of a power supply device) and a light emitting element group 802. The lighting device 800 receives power supply from, for example, the commercial power supply 101 and turns on a light emitting element group 802 such as an LED or an organic EL.

  The power supply circuit 100 converts alternating current input from the commercial power supply 101 into direct current supplied to the light emitting element group 802. The light emitting element group 802 is lit by the direct current converted by the power supply circuit 100.

  The power supply circuit 100 includes a power factor correction circuit 110, a power conversion circuit 120 (an example of a constant current power supply unit), a control arithmetic circuit 112, and a voltage detection circuit 123 (an example of a voltage detection unit).

  The power factor correction circuit 110 includes a rectifier circuit 102 and a booster circuit 111. The rectifier circuit 102 receives an alternating current (for example, a single-phase alternating current of 50 Hz (hertz) to 60 Hz, an effective voltage of 85 V (volt) to 265 V) from the commercial power supply 101, and rectifies the input alternating current to generate a pulsating flow. The booster circuit 111 receives the pulsating current generated by the rectifier circuit 102, boosts the input pulsating current to generate a DC voltage, and controls the input current so that the waveform approximates the input pulsating voltage. And increase the power factor of the input.

  The power conversion circuit 120 includes a step-down circuit 121, a current detection circuit 122, and an integration circuit 130. The step-down circuit 121 receives the direct current generated by the power factor correction circuit 110 and steps down the input direct current to generate direct current to be applied to the light emitting element group 802. The current detection circuit 122 detects a current flowing through the light emitting element group 802. The integration circuit 130 receives the target current value commanded from the control arithmetic circuit 112. The power conversion circuit 120 adjusts the DC voltage value generated by the step-down circuit 121 so that the current value detected by the current detection circuit 122 matches the target current value received by the integration circuit 130. Accordingly, the power conversion circuit 120 drives the light emitting element group 802 with a constant current.

  The control arithmetic circuit 112 stores, as a constant current value table, data in a table format that indicates a range of current values necessary for driving at least two types of light emitting element groups 802. The constant current value table includes a digital value in which a current value necessary for obtaining a desired light emission output for each type of the light emitting element group 802 is set in stages between dimming degrees of 100% to 0%. This constant current value table is set in advance and stored in the control arithmetic circuit 112.

  The dimmer 103 sends a PWM (pulse width modulation) signal to the power supply circuit 100 as a dimming signal for adjusting the light emission output of the light emitting element group 802. For example, the PWM signal output from the dimmer 103 changes when the pulse width duty is between 100% and 5%. It is assumed that the duty of the PWM signal does not fall below 5%.

  The control arithmetic circuit 112 reads the dimming signal, reads the digital value in the constant current value table according to the ratio indicated by the duty of the dimming signal, and converts the digital value into a PWM signal corresponding to the target current value. Then, it is sent to the integration circuit 130. The integration circuit 130 converts the PWM signal from the control arithmetic circuit 112 into a DC voltage and sends the DC voltage to the step-down circuit 121. The step-down circuit 121 generates a load voltage to flow a current to the light emitting element group 802 so that the voltage detected by the current detection circuit 122 and the voltage corresponding to the target current value output from the integration circuit 130 are the same. Adjust. That is, the power conversion circuit 120 can drive the light emitting element group 802 at a constant current with the target current value determined by the dimming signal of the dimmer 103 and the constant current value table of the control arithmetic circuit 112.

  Thus, the power supply circuit 100 operates as a high power factor and high efficiency constant current circuit by the power factor improvement circuit 110 performing power factor improvement and the power conversion circuit 120 performing constant current driving.

  At least two types of light emitting element groups 802 having different numbers of light emitting elements in series (number of lamps) and different constant current values to be driven are selectively connected to the power supply circuit 100.

  When power is turned on, that is, when supply of power from the commercial power supply 101 to the power supply circuit 100 is started, the power factor correction circuit 110, the power conversion circuit 120, and the control arithmetic circuit 112 start to operate. A signal instructing the light emitting element group 802 to be driven with a small current is sent from the control arithmetic circuit 112 to the power conversion circuit 120 for a certain period after the power is turned on. The voltage detection circuit 123 detects the voltage of the light emitting element group 802 when driving with a small current value. The control arithmetic circuit 112 reads the voltage, compares it with a preset value, and determines the number of lamps of the connected light emitting element group 802. After that, the control arithmetic circuit 112 uses a preset constant current value table corresponding to the number of connected lamps, and uses a constant current value corresponding to the ratio of the dimming signal from the dimmer 103 to the light emitting element group. A signal instructing to drive 802 is sent to the power conversion circuit 120.

  FIG. 2 is a circuit diagram illustrating an example of a specific circuit configuration of the lighting device 800.

  In FIG. 2, the lighting device 800 includes the power supply circuit 100 including the power factor correction circuit 110, the control arithmetic circuit 112, and the power conversion circuit 120, and the light emitting element group 802 as described above.

  The light emitting element group 802 includes, for example, an LED series circuit 851 in which LEDs are electrically connected in series as light emitting elements. The LED series circuit 851 is lit at a desired brightness by being driven at a constant current with a target current value determined by the power supply circuit 100 and the dimmer 103.

  In the present embodiment, the LED series circuit 851 connects the LEDs in 40 lamp series or 20 lamp series. That is, in the present embodiment, as the LED series circuit 851, one of 40 LEDs connected in series or 20 LEDs connected in series is connected to the power supply circuit 100 and used. In order to obtain a desired light output by the 40 LED series circuit 851, it is necessary to flow a current of 400 mA to 0 mA in order to obtain a desired light output from 300 mA (milliampere) to 0 mA and 20 LED series circuit 851. is there. The required light output differs between the 40 lighting fixtures and the 20 lighting fixtures.

  The target current value is a constant current value that is desired to flow through an arbitrary LED series circuit 851, and can be set by a dimming signal. The target current value changes according to the current value of the current flowing through the LED series circuit 851 × the duty ratio (duty ratio) of the dimming signal. That is, in the case of 40 LED series circuit 851, the target current value is adjusted between current value 300 mA × dimming signal 100% to 5% → target current value 300 mA to 15 mA. In this case, the current value is adjusted to 400 mA × the dimming signal 100% to 5% → the target current value 400 mA to 20 mA.

  As described above, the power factor correction circuit 110 is, for example, a boost converter circuit, and mainly includes a rectifier circuit 102 and a boost circuit 111.

  The rectifier circuit 102 includes, for example, a diode bridge DB11 and a capacitor C12. The diode bridge DB11 is formed by bridge-connecting four rectifying elements, and generates a pulsating voltage by full-wave rectifying the AC voltage input from the commercial power supply 101. The capacitor C12 is a capacitor having a relatively small capacity, and is used mainly for the purpose of cutting high frequency noise.

  The booster circuit 111 includes, for example, a transformer T60, a switching element Q71, a diode D12, a smoothing capacitor C13, input voltage side voltage dividing resistors R12 and R13, a current detection resistor R14, an output voltage side voltage dividing resistors R15 and R16, and a control IC 141 ( Integrated circuit).

  The transformer T60 has a main winding L61 and an auxiliary winding L62. For the control IC 141, for example, a control IC for power factor correction (PFC) is used. In the present embodiment, a field effect transistor (hereinafter referred to as “FET”) is used as the switching element Q71. However, the switching element Q71 is not limited to an FET, and may be another electrical switch such as a bipolar transistor. Alternatively, a switch by another mechanism such as a mechanical type may be used. The control IC 141 turns on / off the switching element Q71 at a high frequency (for example, several tens of kHz (kilohertz) to several hundreds of kHz), thereby accumulating energy in the main winding L61 of the transformer T60 in the on period and accumulating in the off period. The smoothing capacitor C13 is charged with energy and energy supplied from the rectifier circuit 102. Thus, the smoothing capacitor C13 is charged with a voltage higher than the peak voltage of the pulsating voltage output from the rectifier circuit 102 (hereinafter referred to as “input voltage”). The booster circuit 111 outputs the voltage charged in the smoothing capacitor C13 as an output voltage. The two voltage dividing resistors R12 and R13 detect the voltage value of the input voltage. The auxiliary winding L62 of the transformer T60 detects the timing when the current of the main winding L61 of the transformer T60 ends. The current detection resistor R14 detects the value of the current flowing through the switching element Q71. Based on these detection results, the control IC 141 adjusts the timing for turning on / off the switching element Q71 so that the waveform of the current flowing into the power conversion circuit 120 becomes a waveform that approximates the waveform of the input voltage. As a result, since the power factor is improved, the power factor of the power supply circuit 100 approaches 1 and the harmonic regulation can be dealt with. Further, an output voltage divided by the voltage dividing resistors R15 and R16 is input to the control IC 141. In this way, the on / off ratio of the switching element Q71 is controlled so that the set output voltage is obtained. Generally, the output voltage of the power factor correction circuit is often set higher than the peak voltage of the input voltage of the power factor correction circuit. For example, if the maximum input voltage is AC (alternating current) 265V, it is set to DC 400V or higher.

  The control arithmetic circuit 112 includes a microcomputer 151, for example.

  The microcomputer 151 reads the duty of the dimming signal output from the dimmer 103 and selects a target current value that matches the duty ratio of the dimming signal from a constant current value table set in advance by a software program. Then, a PWM signal corresponding to the selected target current value is sent to the integration circuit 130.

  The constant current value table is a digital value obtained by dividing the constant current value necessary for lighting the connected LED series circuit 851 with a desired light emission output into several steps to several hundred steps between dimming degrees of 100% to 0%. Store.

  FIG. 3 is a block diagram showing the configuration of the microcomputer 151.

  In FIG. 3, the microcomputer 151 includes a memory 152 (an example of a storage unit), a determination unit 153, and a control unit 154. Here, in order to make the explanation of the operation easy to understand, the software operation in the microcomputer 151 is expressed as the operation of the determination unit 153 and the control unit 154. Note that the software program is stored in the memory 152. The determination unit 153 and the control unit 154 may be realized only by software, or may be realized by a combination of software and hardware.

  The memory 152 stores a constant current value table for the 40 LED series circuit 851 and a constant current value table for the 20 LED series circuit 851. In the constant current value table for the 40 LED series circuit 851, digital values corresponding to current values of 300 mA to 0 mA are set and stored in tens to hundreds of steps. In the constant current value table for the LED series circuit 851 of 20 lamps, digital values corresponding to current values of 400 mA to 0 mA are set and stored in several tens to several hundred steps.

  As described above, the constant current value tables previously written in the memory 152 are for 300 mA and 400 mA, and each stores digital value data corresponding to a dimming degree of 100% to 0%.

  The determination unit 153 determines whether the LED series circuit 851 has 40 or 20 lamps.

  The control unit 154 reads a digital value corresponding to the duty of the dimming signal from the dimmer 103 from the constant current value table for the LED series circuit 851 of the number of lamps determined by the determination unit 153, and reads it out of the pulse width. The duty cycle is converted to a PWM signal and sent to the integration circuit 130. The integration circuit 130 receives the PWM signal and generates a DC voltage corresponding to the target current value from the pulse width. A DC voltage corresponding to the target current value output from the integration circuit 130 is input to an error amplifier A45 in the step-down circuit 121 described later. Note that the signal sent from the control unit 154 to the integration circuit 130 may be a DC voltage. In this case, the control unit 154 reads a digital value corresponding to the duty of the dimming signal from the dimmer 103 from the constant current value table, converts it to an analog voltage value, and sends it to the integrating circuit 130. . The integrating circuit 130 functions as a filter composed of CR (capacitor and resistor), and sends a DC voltage corresponding to the target current value to the error amplifier A45.

  As described above, the dimmer 103 is a PWM signal (for example, the frequency is fixed and the duty of the pulse width changes between 100% and 5%) for changing the brightness of the lighting device 800, for example. Output as. The range in which the drive current of the LED series circuit 851 can be changed by the dimmer 103 is, for example, 300 mA to 15 mA when the number of lamps of the LED series circuit 851 is 40, and 400 mA to 15 mA when 20 lamps are used.

  The dimming signal output from the dimmer 103 is input to the microcomputer 151. The control unit 154 of the microcomputer 151 receives the dimming signal, and selects a digital value that becomes a target current value corresponding to the duty of the pulse width of the dimming signal from the constant current value table stored in advance in the memory 152. look for. The control unit 154 of the microcomputer 151 converts the digital value of the target current value into a PWM signal and sends it to the integration circuit 130. The integration circuit 130 integrates the PWM signal of the target current value to convert it into a DC voltage necessary for flowing the target current value. The integrating circuit 130 sends a voltage corresponding to the target current value to the error amplifier A54. By doing so, the contents of the dimming signal output from the dimmer 103 can be reflected as a constant current value for driving the LED series circuit 851.

  When the dimmer 103 is not connected, that is, when the dimming signal is not input to the microcomputer 151, the control unit 154 of the microcomputer 151 recognizes the state where the dimming signal does not exist, and stores the dimming signal in the constant current value table. Then, the power conversion circuit 120 is commanded to perform constant current driving of the LED series circuit 851 with a constant current value corresponding to a dimming degree of 100%. That is, the control unit 154 of the microcomputer 151 drives the LED series circuit 851 at a constant current at 300 mA when the LED series circuit 851 has 40 lights and at 400 mA when the LED series circuit 851 has 20 lights. Here, an example in which the LED series circuit 851 is driven with a constant current corresponding to a dimming degree of 100% in the constant current value table when the dimmer 103 is not connected is shown. The current value of the current that drives 851 can be freely set by software of the microcomputer 151.

  2, the power conversion circuit 120 is, for example, a step-down converter circuit (step-down DC / DC converter) as described above, and includes a step-down circuit 121, a current detection circuit 122, and an integration circuit 130.

  The step-down circuit 121 includes, for example, a switching element Q72, a diode D13, a choke coil L65, a capacitor C14, a pulse transformer T61, a control IC 142, and an error amplifier A45. The current detection circuit 122 is, for example, a current detection resistor R17.

  The switching element Q72 is not limited to the FET as in the switching element Q71, but may be an electrical switch such as a bipolar transistor or a switch using another mechanism. The control IC 142 is a control IC for switching power supply, for example. The pulse transformer T61 is, for example, an insulating transformer, and performs insulation when the switching element Q72 connected to the high potential side of the output voltage of the power factor correction circuit 110 is driven from the control IC 142 connected to the low potential side. Used for. The control IC 142 turns on / off the switching element Q72 at a high frequency (for example, several tens of kHz to several hundreds of kHz) via the pulse transformer T61. In the ON period of the switching element Q72, the output voltage of the power factor correction circuit 110 is transmitted into the power conversion circuit 120. That is, the capacitor C14 is charged while accumulating electromagnetic energy from the smoothing capacitor C13 to the choke coil L65. In the off period of the switching element Q72, the electromagnetic energy stored in the choke coil L65 is charged through the diode D13 while charging the capacitor C14. By repeating the ON / OFF period of the switching element Q72, a voltage lower than the voltage input to the power conversion circuit 120 (that is, the DC voltage generated by the power factor correction circuit 110) is applied to the capacitor C14 in the LED series. The circuit 851 is charged as a load voltage necessary for flowing a target current value. The load voltage charged in the capacitor C14 is a total voltage of a voltage necessary for flowing a current having a target current value to the LED series circuit 851 and a voltage drop in the current detection resistor R17. However, the voltage generated by the voltage drop of the current detection resistor R17 is considerably smaller than the voltage for driving the LED series circuit 851 with the target current value.

  The current detection resistor R17 is electrically connected in series with the LED series circuit 851. The same current as the current flowing through the LED series circuit 851 flows through the current detection resistor R17.

  The integrating circuit 130 receives the PWM signal corresponding to the target current value output from the microcomputer 151, and integrates the received PWM signal to generate a DC voltage corresponding to the target current value.

  The error amplifier A45 is an operational amplifier, for example, and changes the output signal so that the voltages applied to the two input terminals are equal. In the present embodiment, the error amplifier A45 receives a DC voltage corresponding to the target current value from the integration circuit 130 and a voltage generated in the current detection resistor R17. The voltage generated in the current detection resistor R17 is the current flowing in the LED series circuit 851 × the voltage drop of the current detection resistor R17. The error amplifier A45 sends an output signal to the control IC 142 so that the DC voltage corresponding to the target current value from the integration circuit 130 is equal to the voltage drop of the current detection resistor R17. The control IC 142 receives the output signal from the error amplifier A45 and adjusts the on / off duty ratio of the switching element Q72 via the pulse transformer T61. Thereby, the load voltage charged to the capacitor C14 can be adjusted so that the current flowing to the LED series circuit 851 becomes the target current value.

  By repeating the above operation, the power conversion circuit 120 operates so that the voltages at the input terminals of the error amplifier A45 coincide with each other. Therefore, the LED series circuit 851 is always set at the target current value corresponding to the dimming signal. Can drive. Therefore, the power conversion circuit 120 can drive the LED series circuit 851 at a constant current with the current of the target current value determined by the duty ratio of the dimming signal from the dimmer 103 and the constant current value table.

  The voltage detection circuit 123 includes voltage dividing resistors R18 and R19, for example.

  As described above, the LED series circuit 851 uses either one of 40 LEDs connected in series or 20 of LEDs connected in series. Before the power is turned on, it cannot be recognized whether the LED series circuit 851 in the 40 lamp series or the LED series circuit 851 in the 20 lamp series is connected to the power supply circuit 100. Therefore, it is necessary to determine the number of lamps. The lamp number determination is a circuit operation for determining whether the LED series circuit 851 connected to the power supply circuit 100 is a 40-lamp LED series circuit 851 or a 20-lamp LED series circuit 851. The voltage dividing resistors R18 and R19 are used for determining the number of lamps.

  First, when the lighting device 800 is turned on, that is, when an AC voltage having a commercial frequency is input from the commercial power source 101, the input AC voltage is rectified into a pulsating voltage by the rectifier circuit 102, and the booster circuit 111. Sent to. Since the booster circuit 111 corresponds to a booster converter of a PFC circuit, the output voltage is charged to the smoothing capacitor C13 so that the voltage becomes larger than the peak voltage of the pulsating voltage obtained by rectifying the AC voltage while improving the power factor. To do.

  At this time, the control unit 154 of the microcomputer 151 that has started the operation does not know whether there are 40 lights or 20 lights at this time, regardless of the presence or absence of the dimming signal from the dimmer 103 and the duty ratio of the dimming signal. ) A PWM signal for sending a constant current of 15 mA to the LED series circuit 851 is sent to the integration circuit 130. The integration circuit 130 converts the PWM signal into a DC voltage necessary for flowing a current of 15 mA through the LED series circuit 851, and sends the DC voltage to the error amplifier A45. The error amplifier A45 sends an output signal to the control IC 142 so that the voltage drop generated in the current detection resistor R17 and the DC voltage input from the integration circuit 130 are the same. The control IC 142 controls the on / off ratio of the switching element Q72 via the pulse transformer T61 based on the output signal from the error amplifier A45, so that a constant current of 15 mA flows in the LED series circuit 851. Adjust the voltage to charge.

  Since the power conversion circuit 120 operates as a constant current circuit, the current flowing through the LED series circuit 851 is determined by the voltage entering the error amplifier A45, and even if the connected LED series circuit 851 is 40 lamps, 20 lamps are used. Even if it exists, it is driven at a constant current of 15 mA.

  The voltage dividing resistors R18 and R19 divide the voltage applied to the LED series circuit 851, and send the divided voltage to the microcomputer 151.

  The determination unit 153 of the microcomputer 151 applies the voltage applied to the LED series circuit 851 while the LED series circuit 851 is driven at a constant current of 15 mA at the timing when the preset lamp number determination start time has elapsed since the power was turned on. The voltage divided by the voltage dividing resistors R18 and R19 is taken in by the A (analog) / D (digital) port. The lamp number determination start time is the time from when the power is turned on to when the voltage of the LED series circuit 851 is taken into the A / D port, and is stored in the memory 152 of the microcomputer 151 in advance. The determination unit 153 of the microcomputer 151 compares the voltage acquired by dividing by the voltage dividing resistors R18 and R19 with the data of the lamp number determination voltage (corresponding to 80V as will be described later). In order to determine whether the LED series circuit 851 has 40 lamps or 20 lamps, the lamp number determination voltage has a small current (the less current between 40 lamps and 20 lamps at a dimming degree of 5%, In the embodiment, it is a reference voltage value to be compared with the voltage measured when 15 mA) is applied, and is stored in the memory 152 of the microcomputer 151 in advance. As described above, the voltage applied to the LED series circuit 851 is not input to the microcomputer 151 as it is, but the voltage detected by the voltage detection circuit 123 is input. The voltage detection circuit 123 is, for example, voltage dividing resistors R <b> 18 and R <b> 19, and divides a high voltage applied to the LED series circuit 851 and converts it to a low voltage suitable for input to the microcomputer 151. Therefore, the lamp number determination voltage stored in the memory 152 of the microcomputer 151 is a value that takes into account the ratio of the voltage dividing resistors R18 and R19. The determination unit 153 of the microcomputer 151 determines that the voltage acquired by dividing the voltage corresponds to the lamp number determination voltage (80 V) from the ratio of the voltage dividing resistors R18 and R19 (the lamp number determination stored in the memory 152 of the microcomputer 151). Voltage) or more, it is determined that the LED series circuit 851 is 40 lamps in series. On the other hand, if the voltage is less than the voltage corresponding to the lamp number determination voltage (80 V) (the lamp number determination voltage stored in the memory 152 of the microcomputer 151), it is determined that the LED series circuit 851 is 20 lamps in series.

  As described above, in the present embodiment, the power conversion circuit 120 included in the power supply circuit 100 is connected to the light emitting element group 802 (for example, the LED series circuit 851) connected in series, and outputs a constant current to the light emitting element group 802. Then, the light emitting element group 802 is turned on. The memory 152 of the microcomputer 151 provided in the power supply circuit 100 includes a configuration of the light emitting element group 802 (for example, the number of LEDs constituting the LED series circuit 851), a dimming degree of the light emitting element group 802, and a constant current output from the power conversion circuit 120. Is stored in advance as a constant current value table. A voltage detection circuit 123 included in the power supply circuit 100 detects a voltage applied from the power conversion circuit 120 to the light emitting element group 802. Based on the voltage detected by the voltage detection circuit 123 in a state where a constant current of a predetermined current value (for example, 15 mA) is output from the power conversion circuit 120, the determination unit 153 of the microcomputer 151 determines the light emitting element group 802. The configuration (for example, the number of LEDs configuring the LED series circuit 851) is determined. The control unit 154 of the microcomputer 151 is connected to the dimmer 103 that commands the dimming degree of the light emitting element group 802, and is determined by the determination unit 153 of the microcomputer 151 from the memory 152 (specifically, a constant current value table) of the microcomputer 151. The current value corresponding to the combination of the determined configuration and the dimming degree commanded from the dimmer 103 is read, and the constant current of the read current value is output to the power conversion circuit 120. Thus, one power supply circuit 100 automatically determines which light emitting element group 802 is connected among at least two types of light emitting element groups 802 (for example, LED series circuit 851), and the light emitting element group 802. Thus, the light emitting element group 802 can be driven with a constant current value required by the.

  FIG. 4 is a graph showing the relationship between the voltage and current value of the LED series circuit 851.

  In the present embodiment, as described above, as the LED series circuit 851, one of 40 LEDs connected in series and 20 LEDs connected in series is connected to the power supply circuit 100. An LED has a characteristic that current does not flow unless a certain voltage is applied. The forward voltage of the LED after the current starts to flow varies depending on the value of the current that flows. Since the forward voltage of the LED varies during manufacturing, it is described in a data sheet or the like as a voltage generated when a rated current is passed. In an LED used for illumination, for example, the variation in forward voltage at the time of manufacture is 3.2 V to 4.0 V when a current of 400 mA is passed (temperature + 25 ° C. or the like). In addition, the forward voltage of the LED has a negative temperature characteristic like the diode, and has a characteristic that it becomes lower when the temperature becomes higher and becomes higher when the temperature becomes lower (such as a temperature of −25 ° C. to + 50 ° C.). In FIG. 4, in consideration of characteristics such as manufacturing variations in forward voltage of LEDs, temperature characteristics, and current-voltage characteristics, the LED series circuit 851 is, for example, 40 series lamps, 20 series lamps. The relationship between the voltage of the circuit 851 and the target current value is shown.

  For example, the voltage dividing resistor R18 = 39 kΩ (kiloohm), the voltage dividing resistor R19 = 1 kΩ, and the lamp number determination voltage = 80V are set. The lamp number determination voltage considering the ratio of the voltage dividing resistors R18 and R19 is 80V × (1 kΩ / (39 kΩ + 1 kΩ)) = 2.0V. For example, when the voltage of the LED series circuit 851 when driving at a constant current of 15 mA is 100 V, the voltage detection circuit 123 outputs 2.5 V, and this voltage is equal to or higher than the lamp number determination voltage (2.0 V). Therefore, the determination unit 153 of the microcomputer 151 determines that the number of lights of the LED series circuit 851 is 40. In addition, when the LED series circuit 851 voltage is 60V when driving at a constant current of 15 mA, the voltage detection circuit 123 outputs 1.5V, and this voltage is less than the lamp number determination voltage (2.0V). Therefore, the determination unit 153 of the microcomputer 151 determines that the number of lights of the LED series circuit 851 is 20 lights. As shown in FIG. 4, in both cases of 40 and 20 lamps, the range of 68V to 92V is a voltage that does not occur in this embodiment even if the temperature characteristics are taken into consideration. When the voltage of the LED series circuit 851 when driving at a constant current of 15 mA becomes 80 V, the voltage detection circuit 123 outputs 2.0 V, and this voltage is equal to or higher than the lamp number determination voltage (2.0 V). Therefore, the determination unit 153 of the microcomputer 151 determines that the number of lights of the LED series circuit 851 is 40.

  The voltage detected by the voltage detection circuit 123 is slightly smaller than the voltage generated by the power conversion circuit 120 to flow a constant current through the LED series circuit 851, that is, the voltage charged in the capacitor C14. Strictly speaking, the voltage charged in the capacitor C14 is strictly the voltage applied to the LED series circuit 851 plus the voltage drop of the current detection resistor R17. However, since the voltage due to the voltage drop of the current detection resistor R17 is considerably smaller than the voltage for passing the current through the LED series circuit 851, there is no problem even if it is ignored as the lamp number determination. For example, if the current detection resistance R17 = 1Ω (ohms), the voltage drop will be 15 mV (millivolts) even if a current of 15 mA is passed, so compared to the voltage applied to the LED series circuit 851 (for example, 100 V or 60 V). Pretty small.

  For example, assuming that 40 LED series circuits 851 are connected, from the graph of FIG. 4, the LED series circuit 851 when 15 mA is flowing is taken into consideration even when manufacturing variations and temperature changes are considered. Since the voltage is 80 V or more, the determination unit 153 of the microcomputer 151 determines that the number of lamps of the connected LED series circuit 851 is 40. After the determination unit 153 of the microcomputer 151 determines that there are 40 lights, the control unit 154 of the microcomputer 151 recognizes that the number of connected LED series circuits 851 is 40, and thereafter, the LED of 40 lights Based on the constant current value table for the series circuit 851, a PWM signal that integrates a constant current value (300 mA × the duty ratio of the dimming signal = target current value) corresponding to the dimming signal from the dimmer 103 is integrated. Send to circuit 130. That is, the control unit 154 of the microcomputer 151 controls the PWM signal sent to the integrating circuit 130 after the lamp number determination from the PWM signal for flowing 15 mA to the LED series circuit 851 (40 lamps) from the dimmer 103. The PWM signal is changed to flow an arbitrary target current value (between 300 mA and 15 mA) according to the duty (100% to 5%) of the optical signal.

  The integrating circuit 130 sends a voltage corresponding to the target current value generated according to the PWM signal from the microcomputer 151 to the error amplifier A45. The error amplifier A45 sends an output signal to the control IC 142 so that both terminal voltages are equal.

  In this way, the power supply circuit 100 uses the constant current value table for the 40 LED series circuit 851 (because the 40 series LED series circuit 851 is currently connected) to adjust the dimming from the dimmer 103. The LED series circuit 851 (40 lamps) can be driven at a constant current with an appropriate target current value (between 300 mA and 15 mA) according to the duty ratio (100% to 5%) of the signal.

  Here, the operation when 40 LED series circuits 851 are connected is shown. However, when the 20 LED series circuits 851 are connected, the power supply circuit 100 performs an appropriate target current by the same operation as described above. With the value (between 400 mA and 20 mA), the LED series circuit 851 (20 lamps) can be driven with a constant current. That is, when the power supply circuit 100 takes in the voltage of the LED series circuit 851 and compares it with the data of the lamp number determination voltage at the timing when the lamp number determination start time has elapsed after the power is turned on, the voltage of the LED series circuit 851 is Since it is less than the number determination voltage, it can be determined that the number of lamps of the connected LED series circuit 851 is 20. Therefore, the power supply circuit 100 can set the target current value using the constant current value table for the LED series circuit 851 of 20 lamps thereafter.

  Note that the lamp number determination is performed only when the lamp number determination start time has elapsed after the power is turned on, regardless of whether the number of lamps is 40 or 20. After that, the number of lights is not judged unless the power is turned off and then on again. Therefore, when 20 lamps are connected, after the lamp number determination is completed, constant current driving is performed according to the duty of the dimming signal, and even if the voltage applied to the LED series circuit 851 becomes 80 V or more, the lamp number The determination operation is not performed.

  As described above, in the present embodiment, the control unit 154 of the microcomputer 151 performs the predetermined current value regardless of the dimming degree commanded from the dimmer 103 until a predetermined time has elapsed since the start. A constant current (for example, 15 mA) is output to the power conversion circuit 120, and during that time, the determination unit 153 of the microcomputer 151 determines the configuration of the light emitting element group 802 (for example, the number of LEDs configuring the LED series circuit 851).

  As described above, in the present embodiment, immediately after the power is turned on, the constant current value when measuring the voltage applied to the LED series circuit 851 before determining whether the connected LED series circuit 851 is 40 lights or 20 lights. Is set to 15 mA. In the present embodiment, for example, the duty of the pulse width of the dimming signal is 100% to 5%. For example, the constant current value table is divided into several tens to several hundreds of stages between 300 mA to 0 mA for 40 lamps and 400 mA to 0 mA for 20 lamps corresponding to the duty of the dimming signal.

  For example, in the constant current value table for 40 lamps, a digital value corresponding to 300 mA is set in association with 100% duty of the dimming signal, and a digital value corresponding to 15 mA in association with 5% duty of the dimming signal is set. Is set. In the constant current value table for 20 lamps, a digital value corresponding to 400 mA is set in association with 100% duty of the dimming signal, and a digital value corresponding to 20 mA is set in association with 5% duty of the dimming signal. The

  By doing so, the control unit 154 of the microcomputer 151 after the lamp number determination is completed reads the duty of the input dimming signal, and the digital value of the constant current value table corresponding to the duty is the digital value of the target current value. Become. The control unit 154 of the microcomputer 151 determines the duty of the pulse width of the PWM signal sent to the integration circuit 130 using the digital value of the target current value. Since the integration circuit 130 converts this PWM signal into a DC voltage, at this time, the generated DC voltage becomes a DC voltage corresponding to the target current value. By sending the DC voltage to the error amplifier A45, the power conversion circuit 120 can drive the LED series circuit 851 at a constant current with a target current value determined by a dimming signal and a constant current value table.

  In the present embodiment, for example, the lamp number determination voltage is set to 80V. From the graph of FIG. 4, when considering the variation in manufacturing in the forward voltage of the LED, the temperature change, and the current-voltage characteristics, looking at the voltage of the LED series circuit 851 of the 40 lamp series and the 20 lamp series, for example, at 15 mA In the case of 40 lights, it is 136V to 92V, and in the case of 20 lights, it is 68V to 46V.

  Therefore, in consideration of the accuracy of the A / D acquisition of the microcomputer 151 and other circuit constants, a threshold value for determining whether the number of connected LED lamps is 40 or 20 (a lamp considering the voltage division ratio of the voltage detection circuit 123). As the number determination voltage, a value between the minimum voltage that can be taken by the 40 lights and the maximum voltage that can be taken by the 20 lights is set. In the present embodiment, the lamp number determination voltage is selected between 92 V and 68 V and set to 80 V, for example (2.0 V corresponding to this is the microcomputer as the lamp number determination voltage in consideration of the voltage dividing ratio of the voltage detection circuit 123. 151 is stored in the memory 152).

  In this way, even if the forward voltage of the LED varies during manufacturing and temperature changes, it is possible to stably determine whether the LED series circuit 851 connected to the power supply circuit 100 is 40 lights or 20 lights. Can do.

  As described above, in the present embodiment, the control unit 154 of the microcomputer 151 has a configuration corresponding to a predetermined dimming degree (for example, 5%) from the memory 152 (specifically, a constant current value table) of the microcomputer 151. Among the combinations with the current value (for example, the combination of 40 LED series circuits 851 and 15 mA and the combination of 20 LED series circuits 851 and 20 mA), the combination having the smallest current value was selected and selected. A combined current value (for example, 15 mA) is used as the predetermined current value.

  The configuration of the light emitting element group 802 (for example, the LED series circuit 851) is the first configuration (for example, a configuration in which 40 LEDs are connected in series), and a constant current of a predetermined current value (for example, 15 mA) is output from the power conversion circuit 120. The range of the voltage applied from the power conversion circuit 120 to the light emitting element group 802 when output is the first range (for example, 92 V to 136 V). Further, the configuration of the light emitting element group 802 (for example, the LED series circuit 851) is a second configuration (for example, a configuration in which 20 LEDs are connected in series) different from the first configuration, and the predetermined conversion from the power conversion circuit 120 is performed. This is a voltage range applied to the light emitting element group 802 from the power conversion circuit 120 when a constant current having a current value (for example, 15 mA) is output, and a range that does not overlap with the first range is a second range ( For example, 46V to 68V). At this time, as described above, in the present embodiment, the memory 152 of the microcomputer 151 sets a value (for example, 80 V) between the first range and the second range to a voltage reference value (for example, a lamp). Number determination voltage). The determination unit 153 of the microcomputer 151 includes the voltage detected by the voltage detection circuit 123 in a state where the constant current having the predetermined current value (for example, 15 mA) is output from the power conversion circuit 120, and the memory 152 of the microcomputer 151. Is compared with a reference value (for example, lamp number determination voltage) stored in the battery, and based on the comparison result, whether the configuration of the light emitting element group 802 is the first configuration or the second configuration Determine.

  FIG. 5 is a graph showing a change in voltage (relationship between elapsed time and voltage) after turning on the LED series circuit 851 when the LED series circuit 851 has 40 lamps.

  In FIG. 5, the vertical axis represents the voltage applied to the LED series circuit 851 when determining the number of lamps immediately after power-on, and the horizontal axis represents the time from power-on to constant current driving at the target current value. . The duty of the dimming signal is 100%.

  At time A, power supply to the power supply circuit 100 starts from the commercial power supply 101, and the power factor correction circuit 110, the power conversion circuit 120, and the control arithmetic circuit 112 start to operate.

  At time B, after the output voltage of the power factor correction circuit 110 is charged to the smoothing capacitor C13, the power conversion circuit 120 starts charging the load voltage to the capacitor C14 with a delay. At this time, since the current does not flow unless a certain voltage is applied to the LED, the load voltage rapidly increases.

  At time C, the voltage applied to the LED series circuit 851 reaches a certain voltage × 40 lamps, and current starts to flow. At this time, the current gradually increases toward 15 mA because the control unit 154 of the microcomputer 151 controls the slope of the current change to be constant.

  At time D, the current flowing through the LED series circuit 851 reaches 15 mA.

  At time E, since the lamp number determination start time has elapsed since the power was turned on, the determination unit 153 of the microcomputer 151 takes in the divided voltage of the LED series circuit 851 generated by the voltage dividing resistors R18 and R19. Since the acquired voltage exceeds the voltage corresponding to the lamp number determination voltage 80V, it is determined that there are 40 lamps. After the determination, the current gradually increases at a constant rate toward the target current value corresponding to the duty of the dimming signal of 100%.

  At time F, the current reaches the target current value. Thereafter, the constant current drive is continued at the current target current value of 300 mA unless the setting of the dimming signal is changed.

  Thus, for example, when the dimming signal is set at 100% and the lamp number determination is completed, the control unit 154 of the microcomputer 151 suddenly changes the PWM signal for determining the target current value from 15 mA equivalent to 300 mA equivalent. Instead of switching, the duty of the PWM signal is changed so that the target current value gradually increases at a constant rate. For example, if the change rate is set by software of the microcomputer 151 so as to change at a rate of 1% / 5 msec (milliseconds), the target current value flowing to the LED series circuit 851 from about 15 mA to 300 mA is about 1. It can be changed over a period of 425 seconds. By doing so, the light emission output of the LED does not change abruptly and changes gradually, so that no uncomfortable or uncomfortable feeling is given to humans.

  Even when the power is not turned on, the control unit 154 of the microcomputer 151 changes the setting of the dimmer 103 when, for example, the LED series circuit 851 is turned on with a desired light output when changing the light output of the LED. Even when the duty of the dimming signal is changed, the duty of the PWM signal can be changed toward the target current value that is gently changed as described above. Note that the control unit 154 of the microcomputer 151 gently changes the duty of the PWM signal not only when the target current value increases but also when the target current value decreases.

  For example, when the LED series circuit 851 of 40 lamps is driven at a constant current of 300 mA corresponding to a duty of the dimming signal of 100%, the setting of the dimmer 103 is rapidly changed to set the duty of the dimming signal to 10 When the voltage is changed to%, the microcomputer 151 changes the PWM signal while reducing the PWM signal for supplying the target current value at a rate of 1% / 5 msec until the PWM signal is changed from 300 mA to 30 mA.

  For example, when the 40 LED series circuit 851 is driven at a constant current of 30 mA corresponding to a 10% duty of the dimming signal, the setting of the dimmer 103 is suddenly changed so that the duty of the dimming signal is 70%. Then, the control unit 154 of the microcomputer 151 changes the PWM signal while increasing the PWM signal for causing the target current value to flow from 30 mA to 210 mA at a rate of 1% / 5 msec.

  In this way, even if the control unit 154 of the microcomputer 151 changes the PWM signal toward the target current value at a constant rate even for a sudden change in the dimming signal, the setting of the dimmer 103 is suddenly changed. Even if it is changed (for example, 30% / 5 msec, etc.), it changes only at a constant rate (1% / 5 msec), so the light emission output of the LED changes suddenly and does not cause flicker or discomfort to humans.

  In addition, when the dimming signal is changed more slowly than 1% / 5 msec (for example, 0.5% / 5 msec), the control unit 154 of the microcomputer 151 follows the change (0.5% / 5 msec described above). Then, the PWM signal is changed to the target current value.

  As described above, in the present embodiment, the control unit 154 of the microcomputer 151 determines the current value of the constant current to be output to the power conversion circuit 120 after a certain period of time has elapsed since startup, as a determination unit of the microcomputer 151. Until the current value read from the memory 152 (specifically, the constant current value table) of the microcomputer 151 as the current value corresponding to the combination of the configuration determined by 153 and the dimming degree commanded from the dimmer 103, Change gradually below a certain ratio.

  As described above, the power supply circuit 100 that performs constant current driving according to the present embodiment is completely the same without changing the circuit constants or components of the power supply circuit 100, unlike the power supply circuit that performs constant current driving. In the power supply circuit 100, a plurality of types of light emitting element groups 802 (LED series circuit 851) can be driven at a constant current with different currents.

  Specifically, the power conversion circuit 120 drives the light emitting element group 802 with a constant current according to a signal from the control arithmetic circuit 112. The control arithmetic circuit 112 automatically determines the number of lights in the light emitting element group 802 by measuring the voltage applied to the light emitting element group 802 by the voltage detection circuit 123, and switches the constant current value for driving the light emitting element group 802. . Thus, the power supply circuit 100 can be used as a constant current driving power supply circuit for a plurality of types of light emitting element groups 802 used at different current values.

  As described above, according to this embodiment, at least two LED series circuits 851 having different numbers of lamps and different desired constant current values are automatically determined by one power supply circuit 100, and are matched to the number of each lamp. It can be driven with a constant current value. The power supply circuit 100 of the present embodiment measures in advance the voltage applied to the connected LED series circuit 851 with respect to at least two types of LED series circuits 851 having different numbers of lamps and different desired constant current values. It is possible to determine the number of lamps of the determined LED series circuit 851 and drive with a current value according to the number of connected LED lamps. Although the power supply circuit 100 of the present embodiment is the same constant current driving power supply circuit, it can drive a plurality of LED series circuits 851 having different numbers of lamps and constant current values.

  In this embodiment, immediately after the power is turned on, the current that is passed to determine whether the LED series circuit 851 is 40 lights or 20 lights, regardless of the state of the dimming signal (the dimming signal duty level, dimming signal) 15 mA) (including the case where it does not exist). This is matched to the smaller current value corresponding to 5% of the duty range of the dimming signal in the constant current value table prepared corresponding to the LED series circuit 851 to be connected. Specifically, it is set to 15 mA corresponding to 5% of 300 mA for 40 lamps. The direct current generated by the integrating circuit 130 is determined by the PWM signal output from the microcomputer 151 as the current flowing through the LED series circuit 851. Therefore, the power conversion circuit 120 can be driven with a constant current of 15 mA regardless of whether the number of connected LED lamps is 40 or 20.

  Immediately after the power is turned on, constant current driving is first performed at 15 mA, and the voltage applied to the LED series circuit 851 at that time is measured to determine whether it is 40 lights or 20 lights. Thereafter, using each constant current table, constant current driving is performed with a target current value according to the dimming signal.

  Assume that the voltage when 100 mA is passed is measured in order to determine whether the lamp is 40 lamps or 20 lamps immediately after power-on. At that time, if 40 lamps are connected and the dimming signal is set to 5%, when the lamp number determination is finished, the power conversion circuit 120 starts to operate with 15 mA as a target current value. As a result, immediately after turning on the power, the light is turned on at 100 mA and then reduced to 15 mA. Therefore, the light emission output of the target LED is once increased and reduced. Such a lighting behavior is an unnatural lighting operation, and it seems to be flickering and gives an unpleasant feeling.

  However, as in this embodiment, the current at the time of determining the number of lamps immediately after turning on the power is set to 15 mA, which is the smaller current corresponding to the dimming degree 5% of 40 or 20 lamps in advance. For example, even when the dimming signal is set to 5%, 15 mA → 15 mA in the case of 40 lights, and 15 mA → 20 mA in the case of 20 lights, and the light emission output of the LED is constant or slightly increased. Therefore, constant current driving can be performed with a target current value set by the dimming signal.

  In addition, when the dimming signal is set to 100% and the target current value increases to 300 mA or 400 mA after 15 mA is passed and the lamp number determination is completed, the current is directed toward the light emission output of the target LED. It will increase at a certain rate. Such lighting behavior is a natural lighting operation, does not flicker, and does not cause human discomfort.

  Therefore, as in this embodiment, the current corresponding to the duty ratio of the dimming signal is 5% is the smallest in the LED series circuit 851 in which the current value for determining the number of lamps immediately after the power is turned on is determined in at least two types. Set to the current value. In this way, even in the power supply circuit 100 for determining the number of lamps, immediately after the power is turned on, the current can be increased to a target current value at a constant rate, flickering does not occur, and there is no need to feel uncomfortable. The LED series circuit 851 can be turned on.

  In this embodiment, for example, since the duty of the pulse width of the dimming signal is set to 100% to 5%, the dimming signal from the dimmer 103 is smaller than 4% (4% to 0%). Not output.

  The duty range of the dimming signal output from the dimmer 103 is 100% to 5%, but the constant current value table also sets a range of 5% or less (4% to 0%, etc.). For example, in the constant current value table for 40 lamps, a digital value corresponding to a duty ratio of 4% → 12 mA of the dimming signal and a digital value corresponding to a duty ratio of 1% → 3 mA of the dimming signal are set. In the constant current value table for 20 lamps, a digital value corresponding to a duty ratio of 4% → 16 mA of the dimming signal and a digital value corresponding to a duty ratio of 1% → 4 mA of the dimming signal are set.

  Normally, it is not necessary to use a digital value of a constant current value table of 5% or less in a range where the LED series circuit 851 is changed to a desired brightness, that is, a range where the LED series circuit 851 can be changed by a dimming signal.

  In the present embodiment, the microcomputer 151 supplies 15 mA (the one with a smaller current corresponding to 5% when the number of lamps is not determined) to the connected LED series circuit 851 (which is either 40 lights or 20 lights). Sometimes, the duty of the PWM signal output from the microcomputer 151 is gradually increased from 0% to 5% at a rate of 1% / 5 msec.

  As described above, by gradually increasing the current from 0 to 5% at a constant rate, the LED series circuit can be naturally produced without a sense of incongruity even when the current value reaches 15 mA for determining the number of lamps immediately after the power is turned on. 851 can be turned on.

  In the present embodiment, a light extinction signal indicating light extinction from the dimmer 103 is input to the microcomputer 151 from a state in which the LED series circuit 851 is driven with a desired light emission output (target current value determined by the dimming signal). If the power supply from the commercial power supply 101 is stopped, for example, the microcomputer 151 causes the PWM signal so that the target current value becomes 0% at a constant rate (1% / 5 msec) from the current target current value. Reduce the duty. Since the voltage generated by the integration circuit 130 based on the decreasing PWM signal is input to the power conversion circuit 120, the LED series circuit 851 decreases its current and eventually turns off.

  As described above, the microcomputer 151 in this embodiment does not suddenly change the PWM signal corresponding to the target current value immediately before to the PWM signal corresponding to the current of 0% when the LED series circuit 851 is turned off. For example, the PWM signal is changed at a constant rate (1% / 5 msec), and the current is gradually reduced to 0%. By doing so, the LED series circuit 851 can be turned off without causing human discomfort.

  In addition, the current 300 mA to 0 mA in the constant current value table of the 40 LED series circuit 851, the current 400 mA to 0 mA in the constant current value table of the 20 LED series circuit 851, and the current when determining the number of lamps immediately after the power is turned on. The setting of the value 15 mA, the lamp number determination voltage 80 V, the dimming signal range 100% to 5%, the lamp number determination start time, etc. is an example, and these values can be changed by software of the microcomputer 151. Further, the PWM signal such as the dimming signal can be set similarly even if the duty ratio is reversed (for example, the current value set in the constant current value table is set to 300 mA for the dimming signal 5%). ).

  The PWM signal is an example of a dimming signal, and instead of this, a dimming signal modulated by another method may be used. Further, the LED is an example of a light emitting element, and other types of light emitting elements such as an organic EL may be used instead. Further, the number of light emitting elements is not limited to 40 and 20 lights, and light emitting element groups 802 having other numbers of lights may be used. The types of the light emitting element groups 802 are not limited to two types, ie, the 40 light emitting element groups 802 and the 20 light emitting element groups 802, and three or more types of light emitting element groups 802 each having a different number of lamps are selectively used. May be connected to the power supply circuit 100, and even if the number of lamps is the same, two or more types of light emitting element groups 802 having different types (LED, organic EL, etc.) and characteristics (rated current, rated voltage, etc.) are selected. Alternatively, the power supply circuit 100 may be connected. Further, the target current value may be sequentially calculated instead of being read from the table.

  The power supply circuit 100 of the present embodiment includes at least two types of LED series circuits 851 (40 lamps are 300 mA to 0 mA, 20 lamps are 400 mA to 0 mA), and the number of LED lamps to be connected and the range of the constant current value to be driven are different. The number of LED lamps is automatically determined, and the target current value determined based on the current value range (constant current value table) and dimming signal (the dimming signal duty range 100% to 5%) according to the number of lamps With constant current drive.

  A conventional power supply circuit that performs constant current driving can perform constant current driving even if the number of LED lamps increases or decreases, but a constant current value that serves as a reference (for example, current at a dimming signal of 100%) It was necessary to physically change and modify circuit constants and switches. The power supply circuit 100 according to the present embodiment is different from at least two types of LED series circuits 851 having different numbers of LED lamps connected in series without physically changing or modifying circuit constants or switches. It can be driven at a constant current value.

  The power supply circuit 100 according to the present embodiment has a high power factor and a constant current operation by the power conversion circuit 120 by the power factor improvement operation by the power factor improvement circuit 110 and a constant current of the LED series circuit 851 corresponding to harmonic regulation. It can be used as a current drive power supply circuit.

  The power supply circuit 100 according to the present embodiment stores the constant current value table in the control arithmetic circuit 112, thereby finely adjusting the target in a few tens to hundreds of steps with respect to the change in the duty ratio of the dimming signal. The current value can be adjusted.

  The power supply circuit 100 of the present embodiment has a LED series circuit 851 in a state in which a small current (current corresponding to 5% of the smaller driving current in at least two types of LED series circuits 851) flows immediately after power-on. By measuring the voltage applied to, and then increasing the current to the target current value, the LED can be lit in a natural way without giving discomfort.

  When the LED series circuit 851 is turned off, the power supply circuit 100 according to the present embodiment is not turned off suddenly from the immediately preceding target current value, but turned off while gradually decreasing the current at a constant rate. By doing so, the LED can be turned off in a natural way without giving unpleasant feeling.

  In the power supply circuit 100 of the present embodiment, when the target current value is increased or decreased by changing the dimming signal during lighting, the control arithmetic circuit 112 can change the current faster than a certain rate (1% / 5 msec). Therefore, the light emission output of the LED does not change abruptly. By doing so, even if the setting of the dimmer 103 is suddenly changed, the light emission output of the LED can be increased or decreased in a natural way without causing discomfort.

  The power supply circuit 100 according to the present embodiment uses the lamp number determination voltage set in consideration of variations in the forward voltage of the LED during manufacture, temperature change, and current-voltage characteristics as a determination criterion, so that variations in manufacturing and temperature The number of lamps can be determined without being affected by the change, and at least two types of LED series circuits 851 having different numbers of lamps can be used properly.

  The power supply circuit 100 according to the present embodiment automatically determines the number of LED lamps connected to at least two LED series circuits 851 having different numbers of lamps and different desired constant current values. It can be driven with a constant current value according to the number.

  The power supply circuit 100 of the present embodiment measures in advance the voltage applied to the connected LED series circuit 851 with respect to at least two types of LED series circuits 851 having different numbers of lamps and different desired constant current values. It is possible to determine the number of lamps of the determined LED series circuit 851 and drive with a current value according to the number of connected LED lamps.

  The power supply circuit 100 according to the present embodiment is capable of constant current driving a plurality of LED series circuits 851 having different numbers of lamps and different desired constant current values, although they are exactly the same constant current driving power supply circuit.

  The power supply circuit according to the present embodiment has a different number of lamps (so that it can cope with the number of lamps other than 40 or 20) by simply rewriting the software of the control arithmetic circuit 112 without replacing circuit constants or parts. The LED series circuit 851 can be changed to a different constant current value, and the specification of the power supply circuit 100 can be easily changed.

  Since the power supply circuit 100 of the present embodiment can automatically determine the number of LED lamps connected to the plurality of LED series circuits 851 and can be driven at a constant current value suitable for each, The LED series circuit 851 and the power supply circuit 100 can be connected and used without being conscious of the combination of the LED series circuit 851 and the power supply circuit 100 to be connected at the time of assembly in the factory or at the place where the lighting device is installed. .

Embodiment 2. FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  In this embodiment, an overvoltage determination mechanism using the voltage detection circuit 123 is added to the power supply circuit 100 similar to that of the first embodiment.

  Hereinafter, the mechanism of overvoltage determination using the voltage detection circuit 123 will be described.

  2 and 3, the control arithmetic circuit 112 (determination unit 153 of the microcomputer 151) does not turn on the power, that is, even when the LED series circuit 851 is driven at a constant current according to the duty of the dimming signal. The voltage applied to the LED series circuit 851 is taken in via the voltage detection circuit 123 at regular intervals (for example, every 1 msec). In the memory 152 of the microcomputer 151, a voltage value larger than the maximum voltage value that can be generated in the LED series circuit 851 in consideration of the forward voltage of the LED, the drive current, the temperature range, etc. shown in FIG. It is preset and stored as a voltage. The voltage range that can be reached when driving 40 lamps at a constant current is 92 V to 160 V. Therefore, when the voltage is higher than that, it can be determined that at least one of the LEDs constituting the LED series circuit 851 has an open failure. . Similarly, the voltage range that can be obtained when 20 lamps are driven at a constant current is 46 to 86 V. Therefore, when the voltage is higher than that, it is determined that at least one of the LEDs constituting the LED series circuit 851 has an open failure. be able to.

  For example, when the LED series circuit 851 has 40 lamps, a voltage corresponding to 180V is stored in the memory 152 of the microcomputer 151 as an overvoltage determination voltage. As in the first embodiment, the voltage divided by the voltage dividing resistors R18 and R19 constituting the voltage detection circuit 123 is input to the determination unit 153 of the microcomputer 151. Therefore, the voltage corresponding to the overvoltage determination voltage 180V for 40 lamps, the value obtained by digitizing 4.5V, the voltage corresponding to the overvoltage determination voltage 90V for 20 lights, and the value obtained by digitizing 2.25V are stored in the memory of the microcomputer 151. Stored in 152.

  The determination unit 153 of the microcomputer 151 takes in the voltage applied to the LED series circuit 851 from the voltage detection circuit 123 at a constant cycle (for example, every 1 msec), and compares it with the digital value of the overvoltage determination voltage. When the 40-LED series circuit 851 is driven at a constant current, the determination unit 153 of the microcomputer 151 drives the 20-LED series circuit 851 at a constant current at a voltage of 4.5 V or more corresponding to 180 V. In this case, it is determined that at least one of the LEDs constituting the LED series circuit 851 has an open failure at a voltage of 2.25 V or higher corresponding to 90 V.

  If the LED fails to open while performing constant current driving, current does not flow through the LED series circuit 851, and current detection by the current detection circuit 122 becomes impossible, and the error amplifier A45 sends the control IC 142 to the ON period of the switching element Q72. Send output signal to increase. Even if an open circuit failure has occurred, the current cannot be detected, and the output signal works to further increase the ON interval. Therefore, the power conversion circuit 120 increases the voltage applied to the LED series circuit 851. If the power conversion circuit 120 is not stopped at this stage, the power conversion circuit 120 will eventually generate the maximum voltage that can be output as the load voltage.

  However, in the power supply circuit 100 according to the present embodiment, when the determination unit 153 of the microcomputer 151 determines that the LED of the LED series circuit 851 has an open failure at an earlier stage, the control unit 154 of the microcomputer 151 performs control. The supply of power for operating the IC 141 and the control IC 142 is stopped. By doing so, the operation (switching operation) of the power factor correction circuit 110 and the power conversion circuit 120 is stopped, and the boost operation of the power factor improvement circuit 110 and the constant current drive of the power conversion circuit 120 are stopped.

  As described above, the power supply circuit 100 periodically detects the voltage applied to the LED series circuit 851 by the voltage detection circuit 123. Therefore, in the unlikely event that at least one of the LEDs connected in series fails to open, power conversion When the output voltage of the circuit 120 starts to rise, the operation of the power conversion circuit 120 is stopped when the voltage applied to the LED series circuit 851 exceeds a predetermined value. By doing this, it is possible to prevent the power converter circuit 120 from continuing to output the maximum voltage that can be output, thereby causing the power supply circuit 100 to overheat, and continuing to apply a high voltage to the LED series circuit 851 that is not lit. Can be prevented.

  Further, the determination unit 153 of the microcomputer 151 uses an overvoltage determination voltage for 40 lamps when the constant current value table for 40 lamps is used, and an overvoltage for 20 lamps when the constant current value table for 20 lights is used. By using the judgment voltage in conjunction with each other, it is possible to quickly recognize an LED open failure according to whether it is 40 or 20 lights without applying a high voltage to the LED series circuit 851 that has failed more than necessary. it can.

  As described above, in the present embodiment, the memory 152 of the microcomputer 151 is applied to the light emitting element group 802 from the configuration of the light emitting element group 802 (for example, the number of LEDs constituting the LED series circuit 851) and the power conversion circuit 120. A correspondence relationship with a threshold value of voltage (for example, overvoltage determination voltage) is stored in advance. The determination unit 153 of the microcomputer 151 reads the voltage threshold corresponding to the determined configuration from the memory 152 of the microcomputer 151, and emits light when the voltage detected by the voltage detection circuit 123 exceeds the read voltage threshold. It is determined that the element group 802 has failed. When the determination unit 153 of the microcomputer 151 determines that the light emitting element group 802 has failed, the control unit 154 of the microcomputer 151 causes the power conversion circuit 120 to stop outputting constant current. Thus, according to the present embodiment, when at least one light emitting element of at least two types of light emitting element groups 802 (LED series circuit 851 or the like) has an open failure, it is automatically detected and the light emitting element group 802 is detected. Can be stopped.

  FIG. 6 is a graph showing a voltage change at the time of an open failure of the LED series circuit 851 when the LED series circuit 851 has 20 lights.

  FIG. 6 shows the relationship between the elapsed time and the voltage when at least one LED of the LED series circuit 851 has an open failure (open failure) while the LED series circuit 851 has 20 lamps and is driven at a constant current. ing. The vertical axis indicates the voltage applied to the LED series circuit 851 when an open circuit failure occurs during constant current driving, and the horizontal axis indicates the passage of time.

  Until time G, 20 LED series circuits 851 are driven at a constant current of 400 mA with a dimming signal duty of 100%.

  At time G, one of the LEDs constituting the LED series circuit 851 has an open failure. The power conversion circuit 120 cannot perform constant current driving, and the voltage applied to the LED series circuit 851 starts to rise.

  At time H, since the voltage detected by the voltage detection circuit 123 exceeds the overvoltage determination voltage 90V for 20 lamps, the determination unit 153 of the microcomputer 151 determines that an LED open failure has occurred. The control unit 154 of the microcomputer 151 shuts off the power supply of the control IC 142 that controls the power conversion circuit 120. At this time, a slight time lag occurs until the determination unit 153 of the microcomputer 151 recognizes the open failure and the increase in the voltage applied to the LED series circuit 851 stops. When the increase of the voltage stops, the load voltage charged in the capacitor C14 of the power conversion circuit 120 (the voltage used to drive the LED series circuit 851 at a constant current increases due to an open failure) The voltage gradually decreases with current consumption of the voltage dividing resistors R18 and R19 constituting the detection circuit 123.

  At time I, the voltage charged in the capacitor C14 is discharged by the current consumption of the voltage dividing resistors R18 and R19.

  As described above, the power supply circuit 100 that performs constant current driving according to the present embodiment can detect the voltage applied to the light emitting element group 802 (LED series circuit 851) by the voltage detection circuit 123, and thus is connected in series. When the light emitting element group 802 breaks down and the output voltage of the power conversion circuit 120 starts to rise, the operation of the power conversion circuit 120 is started when the voltage applied to the light emitting element group 802 exceeds a predetermined value. Stop. This prevents the maximum voltage that can be output by the power conversion circuit 120 from being continuously output, the power supply circuit 100 is overheated, and a high voltage is applied to the light emitting element group 802 (LED series circuit 851) that is not lit. You can prevent it from continuing.

  Thus, according to the present embodiment, in a power supply circuit that can drive two or more types of light emitting element groups 802 with constant current without changing circuit constants or components, when the light emitting element group 802 fails, A high voltage can be prevented from being applied to both ends of the light emitting element group 802. The power supply circuit 100 according to the present embodiment detects a voltage applied to both ends of the light emitting element group 802 by the voltage detection circuit 123, and the control arithmetic circuit 112 monitors the voltage so that the light emitting element group 802 breaks down. However, the power conversion circuit 120 can be quickly stopped, and a high voltage can be prevented from being applied to both ends of the light emitting element group 802. The power supply circuit 100 according to the present embodiment converts the power when the voltage applied to the LED series circuit 851 is equal to or higher than the voltage value stored in advance when at least one LED of the connected LED series circuit 851 has an open failure. By stopping the circuit 120, it is possible to prevent a high voltage from being applied to the LED series circuit 851.

  Since the power supply circuit 100 according to the present embodiment periodically detects the voltage applied to the LED series circuit 851 by the voltage detection circuit 123, even if at least one of the LEDs connected in series fails to open, The rise of the load voltage that is the output of the power conversion circuit 120 is monitored, and when the voltage applied to the LED series circuit 851 exceeds a predetermined value, the operation of the power conversion circuit 120 is stopped. This prevents the power converter circuit 120 from continuously outputting the maximum voltage that can be output, causes the power supply circuit 100 to be abnormally overheated by continuing to output the maximum voltage, and the LED series circuit that is not lit It can be prevented that a high voltage continues to be applied to 851.

  In a conventional power supply circuit that performs constant current driving, an overvoltage detection circuit needs to be added separately in order to perform overvoltage detection. In the power supply circuit 100 according to the present embodiment, since the overvoltage determination is performed using the voltage detection circuit 123 for determining the number of lamps, it is not necessary to add a separate overvoltage detection circuit.

  The power supply circuit 100 of this embodiment includes a voltage detection circuit 123. Since the voltage detection circuit 123 is composed of, for example, voltage dividing resistors R18 and R19, it normally functions as a voltage dividing resistor for dividing the voltage applied to the LED series circuit 851 and outputting it to the microcomputer 151. For example, at least one of the LEDs connected in series can function as a discharge resistor that gradually discharges the load voltage that has been charged without being able to drive the capacitor C14 at a constant current due to an open failure.

  Since the power supply circuit 100 according to the present embodiment can perform constant current driving, for example, even when the LEDs constituting the LED series circuit 851 are short-circuited, the remaining LEDs that are not short-circuited are driven by constant current. Can continue.

  Therefore, the power supply circuit 100 of the present embodiment continues constant current drive when the LED of the connected LED series circuit 851 has a short circuit failure, and performs overvoltage detection when an open failure occurs. It is possible to prevent a high voltage from being continuously applied to both ends of the LED series circuit 851.

  In the present embodiment, the power supply circuit 100 is connected to the light emitting element group 802 connected in series, and includes a power conversion circuit 120, a control arithmetic circuit 112, and a voltage detection circuit 123. The power conversion circuit 120 performs constant current driving of the light emitting element group 802. The voltage detection circuit 123 repeatedly detects the voltage applied to the light emitting element group 802 at a constant period. The control arithmetic circuit 112 stops the power conversion circuit 120 when the voltage detected by the voltage detection circuit 123 exceeds a certain voltage. The power supply circuit 100 according to the present embodiment monitors a voltage applied to the light emitting element group 802 at a constant cycle, thereby detecting a voltage increase when the light emitting element is in an open failure (open failure), and quickly converting the power conversion circuit. 120 can be stopped. As a result, the power conversion circuit 120 continues to output the maximum voltage that can be output, the power supply circuit 100 is abnormally overheated by continuing to output the maximum voltage, and a high voltage is applied to the LED series circuit 851 that is not lit. You can prevent them from continuing to join.

  In the present embodiment, as in the first embodiment, the voltage detection circuit 123 detects the voltage applied to the light emitting element group 802. Based on the voltage detected by the voltage detection circuit 123, the control operation circuit 112 determines at least two types of light emitting element groups 802 having different numbers of LED lamps connected in series, and the constant current set for each light emitting element group 802. Drive with. The power supply circuit 100 according to the present embodiment automatically determines two or more types of light emitting element groups 802 having different numbers of LED lamps connected in series, and uses a constant current value table suitable for the light emitting element group 802, and uses a constant current value table. Drive.

  In the present embodiment, as in the first embodiment, the control arithmetic circuit 112 causes the minimum current to flow through the connected light emitting element group 802 after turning on the power, and after a certain time has elapsed, the voltage detection circuit 123 Based on the voltage to be detected, the connected light emitting element group 802 is determined. The power supply circuit 100 of this embodiment can increase the current smoothly to the target current value after the determination by flowing the minimum current through the light emitting element group 802 and performing the lamp number determination. Therefore, the light emitting element group 802 does not flicker and does not give a sense of discomfort to humans.

  In the present embodiment, similarly to the first embodiment, the control arithmetic circuit 112 is connected to the dimmer 103 and flows to the light emitting element group 802 based on the dimming signal input from the dimmer 103. Set the constant current value. The power supply circuit 100 according to the present embodiment can change the target current value that flows through the LED series circuit 851 based on the dimming signal from the dimmer 103.

  In the present embodiment, as in the first embodiment, the control arithmetic circuit 112 does not make the change in the constant current value for driving the light emitting element group 802 larger than a certain ratio. The power supply circuit 100 according to the present embodiment does not change faster than a certain rate (1% / 5 msec) when changing the target current value to be passed through the LED series circuit 851 based on the dimming signal from the dimmer 103. . By following the early change of the dimming signal with a delay and following the slow change of the dimming signal as it is, flickering is prevented and human discomfort is not given.

  In the present embodiment, the voltage detection circuit 123 discharges the output voltage remaining in the power conversion circuit 120 when the light emitting element group 802 fails. The voltage detection circuit 123 can gradually discharge the voltage charged in the capacitor C14 when the power conversion circuit 120 is stopped due to overvoltage detection.

  In addition, the graphs of FIGS. 4, 5, and 6 are examples, and change depending on the specifications and temperature characteristics of the LED to be used. In that case, parameters stored in the memory 152 in the microcomputer 151 such as the lamp number determination voltage, the overvoltage determination voltage, and the lamp number determination start time are changed.

  As mentioned above, although embodiment of this invention was described, you may implement combining 2 or more embodiment among these. Alternatively, one of these embodiments may be partially implemented. Or you may implement combining two or more embodiment among these partially.

  DESCRIPTION OF SYMBOLS 100 Power supply circuit, 101 Commercial power supply, 102 Rectifier circuit, 103 Dimmer, 110 Power factor improvement circuit, 111 Boost circuit, 112 Control arithmetic circuit, 120 Power conversion circuit, 121 Buck circuit, 122 Current detection circuit, 123 Voltage detection circuit , 130 integration circuit, 141, 142 control IC, 151 microcomputer, 152 memory, 153 determination unit, 154 control unit, 800 lighting device, 802 light emitting element group, 851 LED series circuit, A45 error amplifier, C12, C14 capacitor, C13 smoothing Capacitor, D12, D13 diode, DB11 diode bridge, L61 main winding, L62 auxiliary winding, L65 choke coil, Q71, Q72 switching element, R12, R13, R15, R16, R18, R19 voltage dividing resistor, R14, R17 Flow detection resistor, T60 transformer, T61 pulse transformer.

Claims (9)

A constant current power supply unit connected to the light emitting element group connected in series and outputting a constant current to the light emitting element group to light the light emitting element group;
A storage unit that stores in advance a correspondence relationship between the configuration of the light emitting element group, the dimming degree of the light emitting element group, and the current value of the constant current output from the constant current power supply unit;
A voltage detection unit for detecting a voltage applied to the light emitting element group from the constant current power supply unit;
A determination unit that determines the configuration of the light emitting element group based on the voltage detected by the voltage detection unit in a state where a constant current of a predetermined current value is output from the constant current power supply unit;
Connected to a dimmer that commands the dimming degree of the light emitting element group, and from the storage unit, a current value corresponding to a combination of the configuration determined by the determining unit and the dimming degree commanded from the dimmer A power supply apparatus comprising: a controller that reads out and outputs a constant current of the read current value to the constant current power supply unit.   The control unit causes the constant current power source unit to output a constant current of the predetermined current value, regardless of the dimming degree commanded from the dimmer until a predetermined time has elapsed since startup, The power supply apparatus according to claim 1, further comprising: causing the determination unit to determine a configuration of the light emitting element group.   The control unit selects, from the storage unit, a combination having the smallest current value among combinations of a configuration corresponding to a predetermined dimming degree and a current value, and selects the current value of the selected combination as the predetermined current value. The power supply device according to claim 2, wherein the power supply device is used as a power supply device.   After the predetermined time has elapsed since the start of the control unit, the current value of the constant current to be output to the constant current power supply unit is a constant rate or less until the current value read from the storage unit is reached. 4. The power supply device according to claim 2, wherein the power supply device is gradually changed. The storage unit has a first configuration of the light emitting element group and the constant current power source unit outputs the constant current having the predetermined current value to the light emitting element group when the constant current power source unit outputs the constant current. A first range, which is a range of applied voltages, and a second configuration in which the configuration of the light emitting element group is different from the first configuration, and a constant current of the predetermined current value is generated from the constant current power supply unit. A range of voltage applied to the light emitting element group from the constant current power supply unit when output, and a value between the first range and a second range that does not overlap is preliminarily set as a voltage reference value. Remember,
In the state where the constant current of the predetermined current value is output from the constant current power supply unit, the determination unit is configured to reference a voltage detected by the voltage detection unit and a voltage stored in the storage unit. The value is compared, and based on the comparison result, it is determined whether the configuration of the light emitting element group is the first configuration or the second configuration. Power supply. The storage unit stores in advance a correspondence relationship between the configuration of the light emitting element group and a threshold value of a voltage applied to the light emitting element group from the constant current power supply unit,
The determination unit reads a threshold voltage of the voltage corresponding to the determined configuration from the storage unit, and the light emitting element group fails when the voltage detected by the voltage detection unit exceeds the read threshold voltage Judging
6. The power supply according to claim 1, wherein, when the determination unit determines that the light emitting element group has failed, the control unit causes the constant current power supply unit to stop outputting constant current. apparatus. A constant current power supply unit connected to the light emitting element group connected in series and outputting a constant current to the light emitting element group to light the light emitting element group;
A storage unit that previously stores a correspondence relationship between the configuration of the light emitting element group and a threshold value of a voltage applied to the light emitting element group from the constant current power supply unit;
A voltage detection unit for detecting a voltage applied to the light emitting element group from the constant current power supply unit;
A voltage threshold value corresponding to the determined configuration is read from the storage unit, and when the voltage detected by the voltage detection unit exceeds the read voltage threshold value, it is determined that the light emitting element group has failed. And
A power supply apparatus comprising: a control unit that causes the constant current power supply unit to stop outputting a constant current when the determination unit determines that the light emitting element group has failed. The storage unit stores the number of light emitting elements constituting the light emitting element group as a configuration of the light emitting element group,
The number of light-emitting elements constituting the light-emitting element group is determined based on the voltage detected by the voltage detection unit in a state where a constant current having a predetermined current value is output from the constant-current power supply unit. The power supply device according to claim 1, wherein the power supply device is determined. A power supply device according to any one of claims 1 to 8,
A lighting device comprising: a light emitting element group connected in series connected to the power supply device.

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