JP7357199B2 - Lighting devices, light source units and lighting fixtures - Google Patents

Description

The present disclosure relates to a lighting device, a light source unit, and a lighting fixture. More specifically, the present disclosure relates to a lighting device that includes a single-stage converter and lights a light source, a light source unit that includes the lighting device and the light source, and a lighting fixture that includes the light source unit.

As a conventional example of a lighting device, a multi-series LED drive circuit (hereinafter referred to as a conventional example) described in Patent Document 1 will be exemplified. In the conventional example, a DC power source obtained by full-wave rectification of a commercial AC power source is converted into voltage by a DC-DC converter using a switching control method and then supplied to the multiple series LEDs, thereby driving the multiple series LEDs with constant current. do. A conventional DC-DC converter includes a SEPIC (Single Ended Primary Inductance Converter) type converter circuit, a PFC circuit (control device) that controls switching of switching elements of the converter circuit, and the like.

In addition, the conventional example includes an overvoltage detection circuit that detects whether the output voltage has exceeded a predetermined value, and when this overvoltage detection circuit detects a voltage higher than the predetermined value, the output voltage is suppressed via a PFC circuit. It is configured as follows.

Japanese Patent Application Publication No. 2011-82204

In the conventional example, for example, when a disconnection failure occurs in a multi-series LED and the output voltage increases, the overvoltage detection circuit detects the increase in the output voltage and can suppress the output voltage via the PFC circuit. However, in the conventional example, it is not possible to protect the multi-series LED drive circuit (lighting device) when an overcurrent flows through the switching element of the DC-DC converter.

An object of the present disclosure is to provide a lighting device, a light source unit, and a lighting fixture that can protect against overcurrent.

A lighting device according to one aspect of the present disclosure includes a converter circuit that supplies a DC load current to a light source that is a load, and a control circuit that controls switching of a switching element included in the converter circuit. The lighting device includes a constant current circuit that makes the load current a constant current, a control power supply circuit that supplies a control power supply voltage for operation to the control circuit, and an overcurrent exceeding an upper limit flowing through the switching element. and an overcurrent detection circuit that detects. The converter circuit outputs the load current smoothed by an output capacitor. The control power supply circuit is configured to rectify the induced electromotive voltage generated by switching of the switching element and smooth it using a capacitor. The control circuit stops switching control of the switching element when the overcurrent detection circuit detects that the overcurrent is flowing. The constant current circuit continues the operation of making the load current discharged from the output capacitor a constant current even after the control circuit stops switching control of the switching element.

A light source unit according to one aspect of the present disclosure includes the lighting device and a light source lit by the lighting device.

A lighting fixture according to one aspect of the present disclosure includes the light source unit and a fixture body that supports the light source unit.

The lighting device, light source unit, and lighting fixture of the present disclosure have the effect of being able to protect against overcurrent.

FIG. 1 is a perspective view of a lighting fixture and a light source unit according to an embodiment of the present disclosure. FIG. 2 is an exploded perspective view of the lighting fixture and light source unit same as above. FIG. 3 is a circuit configuration diagram of a control device and a lighting device according to an embodiment of the present disclosure. FIG. 4 is an external view of the control device same as above.

Hereinafter, a lighting device, a light source unit, and a lighting fixture according to embodiments of the present disclosure will be described in detail with reference to the drawings. However, each figure described in the embodiment is a schematic diagram, and the ratio of the size and thickness of each component does not necessarily reflect the actual size ratio. Note that the configuration described in the embodiments below is only an example of the present disclosure. The present disclosure is not limited to the following embodiments, and various changes can be made depending on the design etc. as long as the effects of the present disclosure can be achieved.

First, a lighting fixture 3 (hereinafter abbreviated as lighting fixture 3) according to an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2.

As shown in FIGS. 1 and 2, the lighting fixture 3 includes a light source unit 2 (hereinafter abbreviated as light source unit 2) according to an embodiment of the present disclosure, and a fixture body 4 that supports the light source unit 2. The light source unit 2 is removably attached to a fixture body 4 that is directly attached to the ceiling. However, the appliance main body 4 may be embedded in the ceiling, directly attached to the wall, or embedded in the wall.

The instrument main body 4 includes a rectangular box-shaped housing section 40 with an open bottom surface, a pair of reflective plates 41 that protrude obliquely upward from the opening edges on both sides along the longitudinal direction of the housing section 40, and a housing section 40 and A pair of end plates 42 are provided at both longitudinal ends of a pair of reflection plates 41 (see FIG. 2). In the instrument main body 4, hanging bolts (not shown) are inserted into at least two of the plurality of attachment holes 400 provided on the bottom surface of the housing part 40, and nuts (not shown) are inserted into the hanging bolts. (not shown) is tightened to install it on the ceiling. Further, a power supply wire is inserted into any one of the plurality of power supply holes 401 provided on the bottom surface of the accommodating portion 40 . The power line inserted into the power hole 401 is electrically connected to the lighting device 1 via the terminal block 402.

As shown in FIG. 2, the light source unit 2 includes a lighting device 1 (hereinafter abbreviated as lighting device 1) according to an embodiment of the present disclosure, and an LED module 22 that is lit by the lighting device 1. Further, the light source unit 2 further includes a mounting member 21 and a cover 23.

The LED module 22 includes a large number of LEDs 220 and a substrate 221. The substrate 221 is formed into a long rectangular plate shape. A large number of LEDs 220 are mounted in the center of the front surface (lower surface) of the board 221 in the lateral direction, and are arranged in a line at equal intervals along the longitudinal direction of the board 221.

The mounting member 21 is formed of a metal plate into a long square gutter shape. The mounting member 21 has a long rectangular plate-shaped bottom plate 210 and a pair of side plates 211 rising upward from both ends of the bottom plate 210 along the longitudinal direction. The LED module 22 is attached to the lower surface of the bottom plate 210 by a plurality of claws cut and raised from the bottom plate 210. Note that the LED module 22 is electrically connected to an output connector of the lighting device 1 via an electric wire (not shown).

The cover 23 is formed into a semi-cylindrical shape using a synthetic resin having translucency, such as acrylic resin or polycarbonate resin. Further, the cover 23 has a pair of projecting walls 233 that protrude upward along the longitudinal direction. The cover 23 accommodates the mounting member 21 between a pair of projecting walls 233, and has hooks formed at the tips (upper ends) of the pair of side plates 211 of the mounting member 21 at the tips (upper ends) of the pair of projecting walls 233. It is attached to the attachment member 21 by being hooked on.

The lighting device 1 includes a printed circuit board 19 and a case 18 that houses the printed circuit board 19. The printed circuit board 19 is configured by mounting various electronic components including the control device 5 on a rectangular printed wiring board. The case 18 is formed of a metal plate into a long rectangular box shape with one side (lower side) open. The case 18 accommodates the printed circuit board 19 and is fixed to the mounting member 21 with the opening surface facing the bottom surface of the bottom plate 210. Note that the case 18 is electrically connected to the mounting member 21 while being fixed to the mounting member 21. Further, the mounting member 21 is electrically connected to the instrument main body 4 in a state where the light source unit 2 is attached to the instrument main body 4. Therefore, the case 18 of the lighting device 1 is electrically connected to the appliance main body 4 through the mounting member 21.

The circuit configuration of the lighting device 1 is shown in FIG. The lighting device 1 includes a rectifier circuit 10, a converter circuit 11, a control power supply circuit 12, a control device 5, and the like.

The rectifier circuit 10 consists of a diode bridge. The rectifier circuit 10 performs full-wave rectification of an AC voltage supplied from an AC power source 9 such as a commercial power system. A converter circuit 11 is electrically connected to a pair of pulsating output ends of the rectifier circuit 10 . Note that the pulsating output end of the rectifier circuit 10 on the low potential side is electrically connected to the ground.

The converter circuit 11 has a single-stage converter (also called one converter) that can perform voltage conversion and power factor correction in parallel. Specifically, the converter circuit 11 includes a SEPIC type DC/DC converter circuit.

The converter circuit 11 includes an input capacitor C1 that smoothes the ripple voltage output from the rectifier circuit 10. The converter circuit 11 further includes a switching element Q1, a first inductor L1, a second inductor L2, a capacitor C2, a diode D1, a resistor R1, and an output capacitor C3. However, the first inductor L1 and the second inductor L2 may be wound around the same core, or may be wound around different cores. A first end of the first inductor L1 is electrically connected to a first end on the high potential side of the input capacitor C1. A second end of the first inductor L1 is electrically connected to a first end of the capacitor C2. A second end of the capacitor C2 is electrically connected to an anode of the diode D1 and a first end of the second inductor L2. The cathode of diode D1 is electrically connected to the positive electrode of output capacitor C3. The negative electrode of the output capacitor C3 and the second end of the second inductor L2 are electrically connected to the second end (ground) on the low potential side of the input capacitor C1. The switching element Q1 is an enhancement type N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor). A drain of the switching element Q1 is electrically connected to a second end of the first inductor L1 and a first end of the capacitor C2. A source of the switching element Q1 is electrically connected to a second end on the low potential side of the input capacitor C1 via a resistor R1. Further, the second end of the second inductor L2 and the negative electrode of the output capacitor C3 are electrically connected to the low potential second end of the input capacitor C1. Note that the positive electrode of the output capacitor C3 is electrically connected to the positive electrode of the LED module 22, and the negative electrode of the output capacitor C3 is electrically connected to the negative electrode of the LED module 22 via a resistor Rx for measuring the load current If. It is connected.

The converter circuit 11 converts the DC input voltage (for example, 141V DC voltage) smoothed by the input capacitor C1 into a desired DC voltage (for example, 30V to 60V) by controlling the switching of the switching element Q1 as described later. DC voltage). Note that the output voltage (desired DC voltage) of the converter circuit 11 is a DC voltage higher than the lighting start voltage of the LED module 22.

The control power supply circuit 12 includes an auxiliary winding L3, a resistor R2, a diode D2, and a capacitor C4. Auxiliary winding L3 is magnetically coupled to second inductor L2 of converter circuit 11. A first end of the auxiliary winding L3 is electrically connected to a first end of the resistor R2, and a second end of the auxiliary winding L3 is electrically connected to a second end on the low potential side of the input capacitor C1. There is. A second end of resistor R2 is electrically connected to the anode of diode D2. A cathode of diode D2 is electrically connected to a first end of capacitor C4. A second end of the capacitor C4 is electrically connected to a second end on the low potential side of the input capacitor C1.

After the converter circuit 11 is started, the control power supply circuit 12 rectifies and smoothes the voltage induced in the auxiliary winding L3 using a resistor R2, a diode D2, and a capacitor C4, thereby generating a DC control power supply voltage Vcc from both ends of the capacitor C4. Output. The control device 5 operates using the control power supply voltage Vcc supplied from the control power supply circuit 12.

Next, the control device 5 will be explained. The control device 5 includes a control circuit 50 that controls switching of the switching element Q1 of the converter circuit 11, a constant current circuit 51 that makes the load current If (forward current flowing through the LED module 22) a constant current, and an overcurrent detection circuit. Equipped with The control device 5 further includes a dimming control circuit 52, an error amplifier 53, a starting circuit 54, and a starting on/off circuit 55.

Control circuit 50 controls switching of switching element Q1 by applying drive voltage Vg to the gate of switching element Q1 of converter circuit 11. The error amplifier 53 amplifies the difference between the negative electrode voltage of the LED module 22 and the reference voltage Vst, and outputs the amplified difference voltage (feedback voltage) to the control circuit 50. The control circuit 50 adjusts the duty ratio of the drive voltage Vg so that the feedback voltage input from the error amplifier 53 approaches zero. That is, the control circuit 50 performs switching control on the switching element Q1 of the converter circuit 11 so as to output a constant voltage (a voltage higher than the lighting start voltage of the LED module 22) to the LED module 22.

The dimming control circuit 52 converts a PWM (Pulse Width Modulation) signal transmitted via a communication medium such as a signal line into a dimming signal, and outputs the dimming signal to the constant current circuit 51 . The PWM signal is a voltage signal in which the dimming level is replaced with a duty ratio. The dimming level corresponds to the current value of the load current If that the lighting device 1 supplies to the LED module 22. The dimming level when the current value of the load current If is equal to the current value of the rated current of the LED module 22 is defined as 100%. The following relationship exists between the dimming level and the duty ratio of the PWM signal. In other words, the dimming level is set to 100% when the duty ratio is 0 to 5%, and the dimming level is set to 5% (lower limit) when the duty ratio is 98% or higher (excluding 100%). shall be. When the duty ratio is 5 to 98%, the dimming level decreases at a constant rate with respect to the increase in the duty ratio. However, when the duty ratio is 100%, the dimming level is set to 0%, that is, the LED module 22 is turned off.

The dimming control circuit 52 outputs a dimming signal (DC voltage signal) with a maximum voltage value when the duty ratio of the PWM signal is 0 to 5%, and when the duty ratio of the PWM signal is 100%. The voltage value of the dimming signal is set to zero. Then, when the duty ratio of the PWM signal is between 5% and 98%, the dimming control circuit 52 outputs a dimming signal having a voltage value inversely proportional to the duty ratio.

The constant current circuit 51 includes an operational amplifier 510, a voltage/current conversion circuit 511, and a current mirror circuit 512.

The operational amplifier 510 constitutes a differential amplifier together with a feedback resistor (resistor R12) and an input resistor (resistor R11). The differential amplifier (op-amp 510) amplifies the voltage difference (differential voltage Vd) between the dimming signal input from the dimming control circuit 52 and the voltage across the resistor Rx (voltage proportional to load current If). and output it.

The voltage/current conversion circuit 511 converts the differential voltage Vd output from the operational amplifier 510 into a current. The output current of the voltage/current conversion circuit 511 is proportional to the differential voltage Vd.

The current mirror circuit 512 is composed of two transistors TR1 and TR2. The two transistors TR1 and TR2 are each an enhancement type N-channel MOSFET. However, each of the two transistors TR1 and TR2 may be a bipolar transistor. The drain of the transistor TR1 is electrically connected to the output terminal of the voltage/current conversion circuit 511 and the gates of the transistors TR1 and TR2. The drain of the transistor TR2 is electrically connected to the negative electrode of the LED module 22. The sources of each transistor TR1 and TR2 are electrically connected to ground via a resistor Rx.

Thus, the current mirror circuit 512 operates to make the drain current of the transistor TR2, that is, the load current If flowing through the LED module 22, equal to the output current (target current) of the voltage/current conversion circuit 511.

As described above, the constant current circuit 51 operates to make the load current If flowing through the LED module 22 match the target current according to the dimming level instructed by the PWM signal. However, the constant current circuit 51 may include a transistor amplifier circuit instead of the current mirror circuit 512.

The starting circuit 54 creates the control power supply voltage Vcc in place of the control power supply circuit 12 from when the AC power supply 9 starts supplying the AC voltage until the output voltage of the converter circuit 11 is stabilized.

The activation on/off circuit 55 controls the operation of the activation circuit 54 on and off. The startup on/off circuit 55 operates the startup circuit 54 from when the AC power supply 9 starts supplying AC voltage until the output voltage of the converter circuit 11 becomes stable.

It is preferable that the control device 5 controls the constant current circuit 51 so that the load current If is less than the rated value during the operation period of the startup circuit 54 when the AC power supply 9 starts supplying the AC voltage. By operating the control device 5 as described above, it is possible to avoid that the output current of the starting circuit 54 and the output current (load current If) of the constant current circuit 51 increase to near the maximum value at the same time. However, the control device 5 also applies the same method when the dimming level instructed by the PWM signal rises from 0% (state where the LED module 22 is turned off) to an arbitrary dimming level of several tens of percent to 100%. It is preferable to operate as follows.

The overcurrent detection circuit includes a comparator 56. Comparator 56 compares the voltage across resistor R1, which is proportional to the source current of switching element Q1, with threshold voltage Vth. The comparator 56 outputs a low level voltage when the voltage across the resistor R1 is less than the threshold voltage Vth, and outputs a high level voltage when the voltage across the resistor R1 is equal to or higher than the threshold voltage Vth. do. When a high-level voltage is input from the comparator 56, the control circuit 50 stops the converter circuit 11 by stopping the output of the drive voltage Vg. In other words, when an overcurrent flows through the switching element Q1 for some reason and the overcurrent detection circuit (comparator 56) detects the overcurrent, the control device 5 stops the converter circuit 11 to control the lighting device 1 due to the overcurrent. protected from. Note that, when the output voltage of the comparator 56 returns to a low level, the control circuit 50 preferably resumes outputting the drive voltage Vg and operates the converter circuit 11.

Further, it is preferable that the constant current circuit 51 continues the operation of making the load current If a constant current even when a high level voltage is output from the comparator 56. That is, the lighting device 1 lights up the LED module 22 by continuing the operation of the constant current circuit 51 while the discharge current (load current If) is supplied from the output capacitor C3 even after the converter circuit 11 stops. It is preferable.

Here, in the control device 5, the control circuit 50 and the constant current circuit 51 are integrated into one or more integrated circuits and housed in a single package 6 (see FIGS. 3 and 4). The package 6 is made of an electrically insulating material (for example, synthetic resin) and is shaped like a rectangular box (see FIG. 4). Further, a plurality of leads 60 protrude from each of the two side surfaces along the longitudinal direction of the package 6. That is, the package 6 is configured as any one of SOP (Small Outline Package), SSOP (Shrink SOP), or TSOP (Thin SOP).

As described above, the control circuit 50 and the constant current circuit 51 are integrated into one or more integrated circuits and housed in the single package 6. Therefore, in the lighting device 1, in the combination of the SEPIC type converter circuit 11 and the constant current circuit 51, it is possible to suppress ripples in the load current If while suppressing increases in the number of parts and manufacturing costs.

Moreover, it is preferable that the control circuit 50 and the constant current circuit 51 be integrated into one integrated circuit. In the lighting device 1, the control circuit 50 and the constant current circuit 51 are integrated into one integrated circuit, so that the package 6 of the control device 5 can be made smaller.

Here, the lighting device 1 includes a control circuit 50, a constant current circuit 51, and an overcurrent detection circuit (comparator 56) integrated into an integrated circuit and housed in a package 6 to form the control device 5. As a result, the lighting device 1 can further reduce the circuit scale and the number of parts. Furthermore, the lighting device 1 integrates circuits (such as a dimming control circuit 52, a starting circuit 54, and a starting on/off circuit 55) and circuit elements surrounded by a rectangular solid line in FIG. 3, and houses them in a package 6. The control device 5 is configured as follows.

Further, when starting up the converter circuit 11, it is preferable that the control circuit 50 starts switching control of the switching element Q1 after the starting circuit 54 creates the control power supply voltage Vcc. When the converter circuit 11 is activated, it is preferable that the constant current circuit 51 starts operating after the switching control of the switching element Q1 starts. When the converter circuit 11 is activated, if the control circuit 50 and the constant current circuit 51 operate as described above, it is possible to suppress an increase in power consumption of the lighting device 1 (control device 5).

Further, the control circuit 50 can perform switching control on the switching element Q1 so as to reduce the target current (dimming level) of the load current If, at least during the period when the startup circuit 54 is creating the control power supply voltage Vcc. preferable. Furthermore, it is preferable that the control circuit 50 makes the target current during the period smaller than the target current when the converter circuit 11 is started and performing steady operation. The lighting device 1 can suppress an increase in power consumption because the control circuit 50 operates as described above.

Here, if the current consumption of each of the startup circuit 54 and the constant current circuit 51 increases at the same time, there is a high possibility that the amount of heat generated by the control device 5 will also increase. If the heat generation amount of the control device 5 is likely to increase, and the constant current circuit 51 and the starting circuit 54 are integrated into one integrated circuit, the temperature during operation of the control device 5 may rise excessively. There is a risk that this may occur.

On the other hand, the control device 5 determines that when the AC power supply 9 starts supplying AC voltage, there is a period in which the current consumption of the starting circuit 54 increases and a period in which the current consumption (load current If) of the constant current circuit 51 increases. They are configured so that they do not overlap. Therefore, the lighting device 1 integrates the control circuit 50, constant current circuit 51, and starting circuit 54 into one integrated circuit and accommodates them in a single package 6 to control A device 5 can be configured.

A lighting device (1) according to a first aspect of the present disclosure includes a converter circuit (11) that supplies a DC load current (If) to a light source (LED module 22) that is a load; and a control circuit (50) that controls switching of the switching element (Q1) included in the device. The lighting device (1) according to the first aspect includes a constant current circuit (51) that makes the load current (If) a constant current, and detects that an overcurrent exceeding an upper limit is flowing through the switching element (Q1). The overcurrent detection circuit (comparator 56) is provided. The control circuit (50) stops switching control of the switching element (Q1) when the overcurrent detection circuit detects that an overcurrent is flowing.

In the lighting device (1) according to the first aspect, when the overcurrent detection circuit detects that an overcurrent is flowing, the control circuit (50) stops switching control of the switching element (Q1). It can provide protection from electric current.

The lighting device (1) according to the second aspect of the present disclosure can be realized in combination with the first aspect. In the lighting device (1) according to the second aspect, the constant current circuit (51) makes the load current (If) constant even after the control circuit (50) stops switching control of the switching element (Q1). It is preferable to continue the operation.

The lighting device (1) according to the second aspect can continue to light the light source by flowing the load current (If) even for a short time after the converter circuit (11) is stopped.

The lighting device (1) according to the third aspect of the present disclosure can be realized in combination with the first or second aspect. In the lighting device (1) according to the third aspect, the control circuit (50) and the constant current circuit (51) are integrated into one or more integrated circuits and housed in a single package (6). It is preferable.

In the lighting device (1) according to the third aspect, the control circuit (50) and the constant current circuit (51) are integrated into one or more integrated circuits and housed in a single package (6). , it is possible to suppress ripples in the load current (If) while suppressing increases in the number of parts and manufacturing costs.

The lighting device (1) according to the fourth aspect of the present disclosure can be realized in combination with the third aspect. In the lighting device (1) according to the fourth aspect, the overcurrent detection circuit may be integrated into an integrated circuit together with the control circuit (50) and the constant current circuit (51) and housed in the package (6). preferable.

The lighting device (1) according to the fourth aspect can further reduce the circuit scale and the number of parts.

The lighting device (1) according to the fifth aspect of the present disclosure can be realized in combination with the fourth aspect. In the lighting device (1) according to the fifth aspect, the control circuit (50), the constant current circuit (51), and the overcurrent detection circuit are preferably integrated into one integrated circuit.

In the lighting device (1) according to the fifth aspect, the control circuit (50), the constant current circuit (51), and the overcurrent detection circuit are integrated into one integrated circuit, thereby reducing the size of the package (6). can be achieved.

A light source unit (2) according to a sixth aspect of the present disclosure includes a lighting device (1) according to any one of the first to fifth aspects, and a light source lit by the lighting device (1).

The light source unit (2) according to the sixth aspect can protect against overcurrent.

A lighting fixture (3) according to a seventh aspect of the present disclosure includes a light source unit (2) according to the sixth aspect and a fixture body (4) that supports the light source unit (2).

The lighting fixture (3) according to the seventh aspect can protect against overcurrent.

1 lighting device 2 light source unit 3 lighting fixture 4 fixture body 6 package 11 converter circuit 22 LED module (load, light source)
50 Control circuit 51 Constant current circuit 56 Comparator (overcurrent detection circuit)
220 LED (solid-state light emitting device)
Q1 Switching element If Load current

Claims (6)

a converter circuit that supplies a DC load current to a light source that is a load;
a control circuit that controls switching of a switching element included in the converter circuit;
a constant current circuit that makes the load current a constant current;
a control power supply circuit that supplies a control power supply voltage for operation to the control circuit;
an overcurrent detection circuit that detects that an overcurrent exceeding an upper limit is flowing through the switching element;
Equipped with
The converter circuit outputs the load current smoothed by an output capacitor,
The control power supply circuit is configured to rectify the induced electromotive force generated by switching of the switching element and smooth it with a capacitor,
The control circuit stops switching control of the switching element when the overcurrent detection circuit detects that the overcurrent is flowing;
The constant current circuit continues the operation of making the load current discharged from the output capacitor a constant current even after the control circuit stops switching control of the switching element.
lighting device. The control circuit and the constant current circuit are integrated into one or more integrated circuits and housed in a single package.
The lighting device according to claim 1 . The overcurrent detection circuit is integrated into an integrated circuit together with the control circuit and the constant current circuit and housed in the package.
The lighting device according to claim 2 . The control circuit, the constant current circuit, and the overcurrent detection circuit are integrated into one integrated circuit,
The lighting device according to claim 3 . A lighting device according to any one of claims 1 to 4 ,
a light source lit by the lighting device;
Equipped with
light source unit. The light source unit according to claim 5 ,
a fixture body that supports the light source unit;
Equipped with
Lighting equipment .

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