JP2012204152A - Light source turn-on device and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED turn-on device which will not have an overcurrent flowing in the LED even when the LED turn-on device and an LED module are temporarily separated while being supplied with power from a commercial power supply and are connected back again.SOLUTION: When an LED module 4 is removed from a connection connector 3 causing the voltage of a smoothing capacitor 15 to exceed a threshold voltage, an overvoltage detection circuit 7 is actuated and a DC-DC converter 6 is thereby stopped operating. At the same time, a transistor 23 turns on, causing a trigger terminal 24a of a timer IC 24 to turn off momentarily, whereby an output terminal 24b of the timer IC 24 is turned on. While in this on state, a transistor 28 turns on, causing a discharge circuit 60 to turn on. Consequently, a thyristor 29 being supplied with power now has its gate voltage gone and thus turns off.

Description

  The present invention relates to a light source lighting device for a light source that is lit with a direct current. For example, the present invention relates to a light source lighting device that prevents an overcurrent (rush current) that occurs when a light source is removed and remounted.

  In an LED driving apparatus that receives power supply from a commercial power source and drives an LED unit in which a plurality of LEDs are connected in series, a technique for determining whether or not an LED is connected based on an LED voltage threshold and discharging the LED unit is disclosed (for example, Patent Document 1).

JP 2010-55824 A

  In an LED lighting device using a conventional flyback transformer such as Patent Document 1, the LED lighting device using a DC-CD converter is disconnected from the LED while power is supplied from a commercial power source, and the LED is turned on again. When the device and the LED are connected, the LED may break down. This is because the residual charge of the secondary side smoothing capacitor of the flyback power supply flows instantaneously to the LED when the LED is connected. As a result, an overcurrent greater than the rated current flows through the LED, causing the LED to break.

  The present invention provides a lighting device in which an overcurrent does not flow in the LED even when the LED lighting device and the LED are disconnected and the LED lighting device and the LED are connected again in a state where power is supplied from a commercial power source. With the goal.

The light source lighting device of the present invention is
In the light source lighting device that detachably mounts the light source module that lights with direct current, and lights the mounted light source module,
A DC voltage generation circuit for generating a DC voltage, the DC voltage generation circuit having a smoothing capacitor for smoothing the generated DC voltage and supplying the smoothed voltage to the light source module;
A generation stop circuit for stopping generation of the DC voltage by the DC voltage generation circuit when the smoothing voltage exceeds a predetermined threshold voltage;
When the smoothing voltage exceeds a predetermined threshold voltage, a control signal output unit starts outputting a control signal and continues outputting the control signal for a predetermined period;
The control signal output from the control signal output unit is input, and during the input of the control signal, the smoothing voltage stored in the smoothing capacitor is discharged and a light source current indicating a direct current flowing through the light source module flows. And a current control circuit that cuts off the conduction of the path.

  According to the present invention, even when the light source lighting device and the light source module are disconnected while power is supplied from a commercial power source, and the light source lighting device and the light source module are connected again, the LED does not flow overcurrent to the light source. A lighting device can be provided.

1 is a configuration diagram of an LED illumination device 110 according to Embodiment 1. FIG. 3 is a time chart when the LED of Embodiment 1 is attached and detached. 6 is a configuration diagram of an LED illumination device 120 according to Embodiment 2. FIG. 5 is a time chart when the LED of the second embodiment is attached / detached.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of the LED illumination device 110 according to the first embodiment. The LED lighting device 110 includes an LED lighting device 2-1 (light source lighting device) that converts an AC voltage supplied from the commercial power source 1 into a DC voltage supplied to the LED module 4 (light source module), and an LED lighting device 2-1. And a connection connector 3 for electrically connecting the LED module 4 and an LED module 4 connected to the LED lighting device 2-1 by the connection connector 3 and powered by the LED lighting device 2-1. Is done. The LED module 4 can be attached to and detached from the LED lighting device 2-1 via the connection connector 3.

  The LED lighting device 2-1 is a so-called flyback type constant current circuit. The LED lighting device 2-1 detects an overvoltage by a rectifier circuit 5 that rectifies an AC voltage input from the commercial power supply 1, a DC-DC converter circuit 6 (DC voltage generation circuit) that converts the rectified voltage, and the like. An overvoltage detection circuit 7 (generation stop circuit) and an overcurrent prevention circuit 8 are included.

  The DC-DC converter circuit 6 includes a control circuit 11 that controls oscillation, a switching element 12 that is controlled to be turned on and off by the control circuit 11, a transformer 13, and a secondary side that rectifies the voltage transformed by the transformer 13. A rectifier circuit 14, a smoothing capacitor 15 for smoothing the voltage rectified by the secondary side rectifier circuit 14, a discharge resistor 16 for discharging the charge stored in the smoothing capacitor 15, a phototransistor 18 for outputting an overvoltage signal, It comprises a latch output circuit 19 that detects an overvoltage signal and causes the control circuit 11 to latch output.

  The overvoltage detection circuit 7 includes a Zener diode 17 that sets an overvoltage threshold, a phototransistor 18 that is turned on when an overvoltage is detected, a resistor 20, and a resistor 21. When the smoothing voltage of the smoothing capacitor 15 exceeds the overvoltage threshold (predetermined threshold voltage), the overvoltage detection circuit 7 causes the direct current by the DC-DC converter circuit 6 via the phototransistor 18, the latch output circuit 19, and the control circuit 11. Stop generating voltage.

  The overcurrent prevention circuit 8 includes a timer circuit 9 (control signal output unit, timer unit) that operates according to a signal from the overvoltage detection circuit 7, and a current control circuit that turns the current of the LED module 4 on and off by the output of the timer circuit 9. 10-1.

  The timer circuit 9 includes a resistor 22 that operates with an overvoltage detection signal, a transistor 23, a timer IC 24, a resistor 25 that sets an output time of the timer IC 24, and a capacitor 26. When the smoothing voltage of the smoothing capacitor 15 exceeds the overvoltage threshold, the timer IC 24 starts outputting a voltage (control signal) from the output terminal 25b, and may output a voltage (output terminal voltage) from the output terminal 24b for a predetermined period. Continue).

  The current control circuit 10-1 includes a thyristor 29 (conduction cutoff switch) that operates according to the output signal of the timer circuit 9, a resistor 27, a transistor 28, and a capacitor 30. The series connection portion of the resistor 27 and the transistor 28 constitutes a discharge circuit 60 that discharges when the transistor 28 inputs a terminal voltage (control signal) from the output terminal 24 b of the timer IC 24. The transistor 28 of the discharge circuit 60 is turned on while the output terminal voltage output from the timer IC 24 is being input, and the resistor 27 discharges the smoothed voltage stored in the smoothing capacitor 15. The thyristor 29 is disposed in the middle of the LED current paths 51 to 56 flowing through the LED module 4, the discharge circuit 60 discharges the smoothing voltage of the smoothing capacitor 15, and no LED current (light source current) flows. In this case, it is turned off, and conduction of the arranged paths 51 to 56 is interrupted.

  The LED module 4 is composed of the same types of LEDs 4a to 4d.

  Next, each circuit operation | movement of the LED lighting device 2-1 is demonstrated. In the first embodiment, a rectified voltage is output from the rectifier circuit 5 constituting the LED lighting device 2-1 to the DC-DC converter circuit 6, and a DC power source for driving the control circuit 11 is generated. The output terminal 11b of the control circuit 11 turns the switching element 12 on and off. Then, the voltage transformed by the transformer 13 is generated as a rectified voltage (DC voltage) via the secondary side rectifier circuit 14, smoothed (smoothed voltage) by the smoothing capacitor 15, and from the LEDs 4 a to 4 d via the connection connector 3. The LED module 4 is applied to the LED module 4, and a current (light source current) flows through the LED module 4 to light it.

  At this time, although the overvoltage detection circuit 7 and the overcurrent prevention circuit 8-1 are not operating, the LED module 4 is lit by the current flowing through the LED module 4 because the thyristor 29 is ON. The thyristor 29 may be used in a circuit for suppressing an inrush current of the power supply circuit, but the usage mode is different from that of the first embodiment.

Next, each circuit operation when the connection connector 3 is attached to and detached from the LED lighting device 2-1 will be described.
FIG. 2 is a time chart showing a voltage waveform and a current waveform of each circuit of the LED lighting device 2-1.
(A) has shown the electric current (light source current) which flows into LED4a-4d.
(B) shows the output voltage waveform output from the DC-DC converter circuit 6 (voltage waveform across the smoothing capacitor 15).
(C) shows the voltage of the trigger terminal 24 a of the timer circuit 9.
(D) shows the voltage of the output terminal 24 b of the timer circuit 9.
(E) shows the gate voltage of the thyristor 36.

(Time t1: Removal of connection connector 3)
When the LED module 4 connected to the LED lighting device 2-1 is removed while the power is supplied from the commercial power source 1 (time t1), the voltage between the secondary side of the transformer 13 and the smoothing capacitor 15 increases. The overvoltage detection circuit 7 starts to operate at time t2. That is, when a current flows through the Zener diode 17 for detecting overvoltage, the phototransistor 18 is turned on, and the latch output circuit 19 is latched.

(Time t2: Stop of DC-DC converter circuit 6 due to overvoltage detection)
The voltage output from the latch output circuit 19 is applied to the overvoltage detection terminal 11 a of the control circuit 11. When the output voltage from the latch output circuit 19 exceeds the threshold value of the overvoltage detection terminal 11a, the control circuit 11 stops oscillating and the switching element 12 is turned off. Therefore, the DC-DC converter circuit 6 stops (time t2).

  In this way, at time t2, the overvoltage detection circuit 7 operates and the DC-DC converter circuit 6 stops driving because the LED module 4 is disconnected from the connection connector 3. However, residual charges remain in the smoothing capacitor 15, and the residual charges are gradually discharged by the discharge resistor 16. At this time (time t1 when the connector 3 is removed), the thyristor 29 is in the ON state (from time t1 to time t2) due to the residual charge of the smoothing capacitor 15.

(Time t2: Start of output of timer IC 24)
In the first embodiment, when the connection connector 3 is removed, the overvoltage detection circuit 7 operates and the DC-DC converter circuit 6 stops driving.
(1) The transistor 23 is turned on,
(2) By turning off the trigger terminal 24a of the timer IC 24 for a moment, the output terminal 24b of the timer IC 24 is turned on (output state) (time t2).
(3) When the output terminal 24b is turned on, the transistor 28 is turned on, and the gate voltage of the thyristor 29 supplied with the power by the resistor 27 and the capacitor 30 disappears, so that the thyristor 29 is turned off at time t2.

(Set period ΔT)
The output time of the output terminal 24b of the timer IC 24 (period from time t2 to t4) is set by the values of the resistor 25 and the capacitor 26. Hereinafter, the output time of the output terminal 24b set by the values of the resistor 25 and the capacitor 26 (period from time t2 to t4) is referred to as a set period ΔT. The output terminal 24b continues to output for the set period ΔT until the voltage of the smoothing capacitor 15 decreases. Since the transistor 28 is on during the set period ΔT, the thyristor 29 is off (t2 to t4). For this reason, even if the connection connector 3 is connected again during the set period ΔT (t3), no overcurrent flows through the LED module 4 because the thyristor 29 is OFF. When the transistor 28 is on, the voltage of the smoothing capacitor 15 is discharged by the discharge circuit 60.

  When the output of the output terminal 24b is turned off (time t4) with the lapse of the set period ΔT, the transistor 28 is turned off. In this case, the gate voltage of the thyristor 29 is generated by the residual charge of the smoothing capacitor 15 that could not be discharged, and the thyristor 29 may be turned on for a moment (immediately after time t4). However, since the smoothing voltage is sufficiently discharged, the current flowing through the LED is very small, so that the LED module 4 can be prevented from being damaged (time t4).

  When power is supplied from the commercial power source 1 to the LED lighting device 2-1, and the LED lighting device 2-1 is restarted (time t5), the output of the output terminal 24b of the timer IC 24 is OFF. For this reason, the thyristor 29 is turned on and a current flows through the LED module 4 to light it (time t6).

  In the LED lighting device 2-1 of the first embodiment, when the voltage of the smoothing capacitor 15 exceeds the threshold voltage by removing the LED module 4, the overvoltage detection circuit 7 operates to stop driving the DC-DC converter circuit 6. To do. At the same time, the transistor 23 is turned on, the trigger terminal 24a of the timer IC 24 is turned off for a moment, and the output terminal 24b of the timer IC 24 is turned on. In this ON state, the transistor 28 is turned ON, and the discharge circuit 60 is turned ON. As a result, the gate voltage of the thyristor 29 supplied with power is lost, and the thyristor 29 is turned off. In this way, the discharge of the discharge circuit 60 and the interruption of the LED current path by the thyristor 29 are simultaneously performed. Therefore, even if the light source lighting device and the light source module are disconnected while the power supply is supplied from the commercial power source, and the light source lighting device and the light source module are connected again, an LED lighting device is provided in which no overcurrent flows to the light source. it can.

Embodiment 2. FIG.
FIG. 3 is a configuration diagram of the LED lighting device 120 according to the second embodiment. Only differences from the first embodiment will be described below. The LED lighting device 120 includes an LED lighting device 2-2 with respect to the LED lighting device 110 of the first embodiment. The LED lighting device 2-2 has a configuration using a voltage comparison circuit 38 instead of the timer circuit 9 of the LED lighting device 2-1 of the first embodiment.

  The overcurrent prevention circuit 8-2 includes a voltage comparison circuit 38 that compares the comparison reference voltage and the output voltage of the LED lighting device 2, and a current control that turns the current of the LED module 4 on and off based on the output of the voltage comparison circuit 38. The circuit 10-2 is configured.

  The voltage comparison circuit 38 compares the comparison reference voltage with the output voltage and outputs the resistance 21 that generates the comparison reference voltage, the Zener diode 39, the resistance 40 that detects the output voltage of the LED lighting device 2, and the resistance 41. Comparator 44, a transistor 42 operated by the output of the comparator 44, a resistor 43, a resistor 27, and a resistor 45.

  In the LED lighting device 2-1 of the first embodiment, the timer circuit 9 including the timer IC 24 controls the off period of the thyristor 29 with time. In contrast, in the LED lighting device 2-2 of the second embodiment, the output voltage of the LED (the voltage across the smoothing capacitor 15) is detected by the voltage comparison circuit 38 including the comparator 44, and the detected voltage is used. The feature is that the off-period of the thyristor 29 is controlled.

  The current control circuit 10-2 includes a resistor 46 for inputting the output signal of the voltage comparison circuit 38, a transistor 31, a resistor 32, a resistor 33, a transistor 34, a resistor 35, a thyristor 36, and a capacitor 37. Is done.

Next, each circuit operation when the connection connector 3 is detached from the LED lighting device 2-2 will be described.
FIG. 4 is a diagram corresponding to FIG. 2 and is a time chart showing voltage waveforms and current waveforms of each circuit of the LED lighting device 2-2. (A), (b), and (e) in FIG. 4 correspond to (a), (b), and (e) in FIG. 2, and the waveforms are the same. FIG. 4F shows the output terminal voltage of the comparator 44, which is a waveform unique to FIG.

  In the second embodiment, as in the first embodiment, the overvoltage detection circuit 7 operates by removing the connector 3, and the DC-DC converter circuit 6 stops driving (time t1). At the same time, the output terminal of the comparator 44 is switched from Hi to Lo, and the Lo state is maintained until the output voltage (voltage across the smoothing capacitor) sufficiently decreases. This operation utilizes the hysteresis effect of the comparator 44.

  The comparison reference voltage of the comparator 44 is determined by the Zener diode 39 and is input to the + terminal of the comparator 44 as a reference voltage. Since the voltage at the + terminal is higher than the voltage at the − terminal when “normally lit”, the output terminal of the comparator 44 is Hi, so that the gate of the thyristor 36 is turned on via the transistors 31 and 42. . As a result, the LED is turned on.

  The voltage at the negative terminal of the comparator 44 varies depending on the output voltage. In the “normally lit state”, the output terminal of the comparator 44 outputs Hi, so the transistor 42 is in the ON state. The voltage input to the terminal is input by dividing the output voltage by the resistors 40, 41, and 43. When the output voltage increases when the connector 3 is disconnected, the-terminal voltage input by the divided voltage of the resistors 40, 41 and 43 exceeds the reference voltage of the + terminal, so that the output terminal of the comparator 44 is Lo output. (Time t2).

  Once the output terminal of the comparator 44 becomes Lo output, the transistor 42 is turned off. In that case, the voltage at the negative terminal is divided by the resistors 40 and 41, and the voltage ratio at the negative terminal is increased. Therefore, the output terminal of the comparator 44 maintains the Lo state until the output voltage is sufficiently lowered. . At the same time, since the transistor 31 is also turned off, the divided voltage of the resistor 32 and the resistor 33 is input to the base terminal of the transistor 34, the transistor 34 is turned on, and no current flows to the gate of the thyristor 36. For this reason, the thyristor 36 remains OFF (time t2 to t4). Therefore, even if the connection connector 3 is connected again during that time (time t3), no overcurrent flows through the LED module 4. When the output voltage is sufficiently lowered, the output of the comparator 44 is inverted to become a Hi output, and the thyristor 29 is turned on for a moment by the residual charge of the smoothing capacitor 15 that could not be discharged. However, since the current flowing through the LED is very small (because the output voltage is sufficiently lowered), the LED module 4 can be prevented from being damaged (time t4).

  When power is supplied from the commercial power source 1 to the LED lighting device 2-2 and the LED lighting device 2-2 is restarted (time t5), the comparator 44 becomes Hi output, the thyristor 36 is turned on, and the LED module 4 is turned on when a current flows (time t6).

  In the LED lighting device 2-1 of the first embodiment, “OFF of the thyristor 36 and ON of the discharge circuit 60” is controlled according to time. On the other hand, in the LED lighting device 2-2 according to the second embodiment, “the thyristor 36 is turned off and the discharge circuit 60 is turned on” is controlled by the smoothing voltage itself of the smoothing capacitor 15, so that the rush of the LED module 4 can be more reliably performed. Current can be prevented.

  DESCRIPTION OF SYMBOLS 1 Commercial power supply, 2-1, 2-2 LED lighting device, 3 Connector, 4 LED module, 4a-4d LED, 5 Rectifier circuit, 6 DC-DC converter circuit, 7 Overvoltage detection circuit, 8-1, 8- 2 Overcurrent prevention circuit, 9 Timer circuit, 10-1, 10-2 Current control circuit, 11 Control circuit, 11a Overvoltage detection terminal, 11b Output terminal, 12 Switching element, 13 Transformer, 14 Secondary side rectifier circuit, 15 Smoothing Capacitor, 16 Discharge resistor, 17 Zener diode, 18 Phototransistor, 19 Latch output circuit, 20 Resistor, 21 Resistor, 22 Resistor, 23 Transistor, 24 Timer IC, 24a Trigger terminal, 24b Output terminal, 25 Resistor, 26 Capacitor, 27 Resistor, 28 transistors, 29 thyristors, 30 Capacitor, 31 transistor, 32 resistor, 33 resistor, 34 transistor, 35 resistor, 36 thyristor, 37 capacitor, 38 voltage comparison circuit, 39 Zener diode, 40 resistor, 41 resistor, 42 transistor, 43 resistor, 44 comparator, 45 resistor, 46 resistor, 51-56 path, 60 discharge circuit, 110, 120 LED lighting device.

Claims (6)

In the light source lighting device that detachably mounts the light source module that lights with direct current, and lights the mounted light source module,
A DC voltage generation circuit for generating a DC voltage, the DC voltage generation circuit having a smoothing capacitor for smoothing the generated DC voltage and supplying the smoothed voltage to the light source module;
A generation stop circuit for stopping generation of the DC voltage by the DC voltage generation circuit when the smoothing voltage exceeds a predetermined threshold voltage;
When the smoothing voltage exceeds a predetermined threshold voltage, a control signal output unit starts outputting a control signal and continues outputting the control signal for a predetermined period;
The control signal output from the control signal output unit is input, and during the input of the control signal, the smoothing voltage stored in the smoothing capacitor is discharged and a light source current indicating a direct current flowing through the light source module flows. A light source lighting device comprising: a current control circuit that interrupts conduction of a path. The current control circuit is
A discharge circuit for inputting the control signal output from the control signal output unit, and discharging the smoothed voltage stored in the smoothing capacitor during the input of the control signal;
It is arranged in the middle of the path through which the light source current flows, and is turned off when the discharge circuit is discharging the smoothing voltage and the light source current is not flowing. The light source lighting device according to claim 1, further comprising a conduction cut-off switch that cuts off conduction. The control signal output unit is
It has a timer unit that detects that the smoothing voltage exceeds a predetermined threshold voltage and continues output of the control signal for a set period set as the predetermined period with this detection as a trigger. The light source lighting device according to claim 1 or 2. The control signal output unit is
By comparing the reference voltage used as a reference with the smoothing voltage of the smoothing capacitor, it is detected that the smoothing voltage exceeds the predetermined threshold voltage, and triggered by this detection, the ratio of the smoothing voltage to the reference voltage And a voltage comparison unit that continues the output of the control signal for a period when the smoothed voltage with the increased ratio is larger than the reference voltage as the predetermined period. Or the light source lighting device in any one of 2. The light source is
It is LED, The light source lighting device in any one of Claims 1-4 characterized by the above-mentioned.   The illuminating device provided with the light source lighting device in any one of Claims 1-5.

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