JP5469362B2 - Lighting control device - Google Patents

Description

  The present invention relates to a dimming lighting device capable of dimming a light source.

  Conventionally, there is a dimming lighting device that performs dimming control of the light source by controlling the phase of the power supplied to the light source composed of an incandescent bulb, and the phase of the supplied power is turned ON / OFF using a triac as a phase control element It was. However, when the phase control is performed by the triac, there is a problem that a large current flows at the timing when the triac is turned on, stress is applied to the light source and the power source, and the lifetime of these is shortened.

  Therefore, a dimming lighting device that performs dimming control by controlling the amplitude of the sine wave alternating current supplied to the light source using an IGBT (Insulated Gate Bipolar Transistor) or an FET (Field effect transistor) instead of the triac is considered. (See Patent Document 1).

  In the dimmer disclosed in Patent Document 1, switch means for switching connection / disconnection between an AC power source composed of a sine wave and a light source, and a voltage supplied to the light source based on connection / disconnection by the switch means. A smoothing means for smoothing is provided, and an AC voltage smoothed by the smoothing means is supplied to the light source. Here, when the control means controls the connection / disconnection cycle of the switch means, the amplitude of the voltage applied to the light source is controlled in the range of 0 to 100%, and the light source dimming control is performed.

JP 2007-128669 A

  By the way, it is known that IGBT has a low inrush current resistance as compared with triac. Further, it is known that the current value flowing through the incandescent bulb when the temperature of the incandescent bulb is low is several times the current value in the lighting state.

  For this reason, when an IGBT is used as an element for dimming control as in Patent Document 1, lighting is started in a state where the incandescent bulb is cooled, and an AC voltage is applied to the incandescent bulb (FIG. 5A). And a large current value exceeding the inrush current resistance Im of the IGBT flows (see FIG. 5B), and there is a problem that excessive stress is applied to the IGBT.

  The present invention has been made in view of the above-mentioned reasons, and the object of the present invention is to ensure safety even when the incandescent bulb is lit in a cold state without overcurrent flowing through the switching transistor. The object is to provide a lighting device for high dimming.

In order to achieve the above object, according to the first aspect of the present invention, a transistor inserted in a power supply path connecting an AC power source and a light source and switching a sine wave AC from the AC power source, and the transistor is on / off controlled. A switching control unit; a smoothing unit that outputs an alternating voltage obtained by smoothing a voltage switched by the transistor to the light source; a current value measuring unit that measures an output current value of the transistor; and the transistor connected in parallel. The phase control unit controls the lighting power of the light source by controlling the phase of the TRIAC, and the current value measuring unit performs the switching operation at the start of lighting of the light source. When the output current value is equal to or greater than a predetermined threshold, the switching operation by the switching control unit is stopped. Rutotomoni, wherein to perform the triac phase control by the phase control unit, when the output current value is less than the predetermined threshold value, the lighting control section that controls so as to continue the switching operation by the switching control unit, the light source Measuring means for measuring an elapsed time from the end of lighting of the light source, the lighting control unit at the start of lighting of the light source, if the elapsed time is longer than a predetermined time, by the phase control unit of the triac Phase control is performed, and when the time is shorter than a predetermined time, the switching operation by the switching control unit is performed .

According to the first aspect of the present invention, when the value of the current flowing through the switching control unit is equal to or greater than the predetermined threshold, the switching control unit stops the switching operation of the transistor, and the phase control unit controls the phase of the triac, and the light source The lighting power can be supplied. Thereby, even if lighting is started in a state where the light source composed of an incandescent light bulb is cooled, an overcurrent does not flow through the transistor, and a highly safe lighting control lighting device can be provided. In addition, when it is less than the threshold value, the switching operation by the switching control unit is continued and the lighting power of the light source is supplied, so that the stress on the light source and the power source can be reduced compared to the phase control using the triac. . Furthermore, a measuring means for measuring the elapsed time from the end of lighting of the light source is provided, and it can be predicted from this elapsed time whether the light source is cooled. As a result, when it is predicted that the light source has cooled down after a predetermined time has elapsed, the TRIAC can be phase-controlled by the phase control unit at the start of lighting, and the light source can be turned on by supplying lighting power to the light source. In addition, it is possible to prevent overcurrent from flowing through the transistor, and to provide a highly safe dimming lighting device.

It is a schematic circuit diagram which shows the lighting device for light control concerning embodiment of this invention. It is a graph which shows the voltage value in the circuit in the control system, (a) is the supply voltage value of AC power supply, (b) is the control voltage value in a switching control part, (c) is the output voltage value of a transistor, (d ) Represents the lighting voltage value of the light source. It is a schematic block diagram which shows the principal part of the control system It is a graph which shows the electric current value and voltage value at the time of lighting a light source using the control system, (a) is the supply voltage value of an alternating current power supply, (b) is the electric current value which flows through a transistor, (c) is a triac. The flowing current value is shown. (A) is a graph which shows the voltage value of the alternating voltage in the conventional lighting device for light control, (b) is a graph which shows the electric current value which flows through IGBT, when an alternating voltage is applied.

  Hereinafter, a lighting control lighting device according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the dimming lighting device A according to the present embodiment includes a transistor 1 (1a, 1b) inserted in a power supply path that connects an AC power supply 7 that is a commercial power supply and a light source 8 that is an incandescent light bulb. A switching control unit 2 for controlling on / off of the transistor 1, a filter circuit using the coils L1, L2 and the capacitor C, a smoothing unit 3 for smoothing the voltage switched by the transistor 1, A current value measuring unit 4 for measuring the output current value I1, a phase control unit 5 having a triac (not shown) connected in parallel with the transistor 1 and the smoothing unit 3, and an output measured by the current value measuring unit 4. A lighting control unit 6 that controls the switching control unit 2 and the phase control unit 5 based on the current value I1 is provided. The dimming lighting device A includes an operation unit 10 and a setting unit 9 made of a known technique for adjusting the dimming level of the light source 8, and the setting unit 9 is operated by the user operating the operation unit 10. The dimming level value is held in

  The transistors 1a and 1b are each composed of, for example, an n-channel IGBT (Insulated Gate Bipolar Transistor), the collector is connected to the AC power supply 7, and the emitter is connected to the input terminal of the smoothing unit 3. Further, the terminal on the gate side of the transistor 1 is connected to the switching control unit 2, and based on the control voltage from the switching control unit 2, the sine wave AC from the AC power supply 7 is switched and output to the smoothing unit 3. The transistors 1a and 1b are connected to flywheel diodes D that flow currents in opposite directions.

  The switching control unit 2 is connected to the setting unit 9, operates with the power from the AC power supply 7 as operating power, and is a rectangular wave control voltage set at a higher frequency than the AC power supply 7 (see FIG. 2B). ) Is applied to the gate of each transistor 1 to switch the transistor 1. The on-duty indicating the ratio between the on period and the off period of the control voltage shown in FIG. 2B is held by the operating voltage of the light source 8 that performs lighting, the effective voltage of the AC power supply 7, and the setting unit 9. It is determined by the dimming level value of the light source 8.

  Thus, the transistors 1a and 1b receive the rectangular wave control voltage output from the switching control unit 2 and turn on / off the sinusoidal AC voltage output from the AC power supply 7 (see FIG. 2A). The voltage is turned off and the voltage shown in FIG. Further, the light source 8 can be turned on by the smoothing unit 3 smoothing the output voltage into a sinusoidal AC voltage as shown in FIG.

  The current value measuring unit 4 is a known current measuring circuit including, for example, a current transformer, and measures a current value I1 flowing between the transistor 1a and the coil L1.

  The phase control unit 5 includes a triac (not shown), is connected to the setting unit 9, and operates with the operating voltage of the light source 8 that turns on, the effective voltage of the AC power supply 7, and the dimming that the setting unit 9 holds. The phase of the triac is controlled based on the level value, and the lighting power of the light source 8 is output to the light source 8. Thereby, even when the lighting power is supplied to the light source 8 through any path of the phase control unit 5 and the switching control unit 2, the dimming level of the light source 8 can be made equal.

  The lighting control unit 6 has a threshold value Ith set to a current value lower than the endurance current value of the transistor 1, and performs switching based on the threshold value Ith and the absolute value of the current value I1 measured by the current value measuring unit 4. The switching operation of the control unit 2 is started / stopped, and the phase control by the phase control unit 5 is started / stopped. Specifically, when the switching operation by the switching control unit 2 is performed, if the absolute value of the current value I1 is smaller than the threshold value Ith, the switching operation of the switching control unit 2 is continued, and the current value I1 When the absolute value is equal to or greater than the threshold value Ith, the switching operation of the switching control unit 2 is stopped and the phase control by the phase control unit 5 is started. Further, when the phase control by the phase control unit 5 is performed, the phase control by the phase control unit 5 is stopped every half cycle of the AC power supply 7 and the switching operation by the switching control unit 2 is started.

  Further, for example, as shown in FIG. 3, the lighting control unit 6 compares the signal voltage indicating the threshold value Ith and the current value from the current detection unit 4 using the comparator 61, and controls the voltage of the comparison result and the control of the switching control unit 2. The voltage is multiplied by the AND circuit 62 and applied to the transistor 1, and the comparison result is inverted by the NOT circuit 63 and output to the phase controller 5.

  Thereby, when the absolute value of the current value I1 is less than the threshold value Ith, a sine wave alternating current is supplied to the light source 8 via the transistor 1 and the smoothing unit 3, so that stress on the light source 8 and the alternating current power supply 7 is reduced. If the absolute value of the current value I1 is equal to or greater than the threshold value Ith, no signal is input to the transistor 1 and the AC power supply 7 phase-controlled via the phase controller 5 is supplied to the light source 8. Therefore, it is possible to suppress a large current from flowing through the transistor 1 and applying an excessive stress.

  Here, the operation at the start of lighting of the light source 8 when the light source 8 is cold will be described using the graph shown in FIG. First, the lighting control unit 6 starts the switching operation of the switching control unit 2 (t0 in FIG. 4). At this time, the current value I1 of the transistor 1 measured by the current value measuring unit 4 increases rapidly as described above, but when the absolute value of the current value I1 becomes larger than the threshold value Ith (t1 in FIG. 4). The lighting control unit 6 stops the switching operation of the switching control unit 2 and starts phase control by the phase control unit 5. As a result, the current value I1 flowing through the transistor 1 gradually decreases, and an excessive current can be prevented from flowing through the transistor 1.

  Next, when a time corresponding to a half cycle of the AC power supply 7 has elapsed since the start of lighting (t2 in FIG. 4), the lighting control unit 6 stops the phase control by the phase control unit 5 and performs the switching operation by the switching control unit 2. Let it begin. Here, when the light source 8 is not yet sufficiently warmed, the current value suddenly increases again. However, when the absolute value of the current value I1 becomes larger than the threshold value Ith (t3 in FIG. 4), the light source 8 is turned on. The control unit 6 stops the switching operation by the switching control unit 2 and starts the phase control by the phase control unit 5, thereby preventing an excessive current from flowing through the transistor 1.

  Further, when the time corresponding to the half cycle of the AC power supply 7 has elapsed (t4 in FIG. 4), the lighting control unit 6 stops the phase control by the phase control unit 5 and starts the switching operation by the switching control unit 2. Here, when the light source 8 is sufficiently warmed up, the current value I1 gradually rises and falls without exceeding the threshold value Ith, so the lighting control unit 6 stops the operation of the phase control unit 5. The switching operation by the switching control unit 2 is continued.

  In this way, the light source 8 is turned on by the phase controller 5 using the triac having a high endurance current value until the light source 8 is sufficiently warmed and a current smaller than the threshold value Ith flows through the transistor 1. An excessive current can be prevented from flowing through the transistor 1, and a highly safe dimming lighting device can be provided.

  In this embodiment, after the absolute value of the current value I1 becomes larger than the threshold value Ith and the switching operation of the switching control unit 2 is stopped, the lighting control unit 6 performs phase control every half cycle of the AC power supply 7. Although the phase control by the unit 5 is stopped and the switching operation of the switching control unit 2 is started, the same control is performed after a predetermined time elapses regardless of the cycle of the AC power supply 7 or the cycle of the AC power supply 7. May be performed.

In addition, the lighting control unit 6 starts the switching operation of the switching control unit 2 at the start of lighting of the light source 8, but the lighting control unit 6 measures the elapsed time from the lighting end time of the light source 8. the provided section, when a predetermined time has elapsed, without starting the switching operation of the switching control section 2, may start the phase control by the phase control unit 5. In addition, after the phase control by the phase control unit 5 is started, the phase control by the phase control unit 5 is stopped and switched after a predetermined time when the light source 8 is expected to be warmed or every cycle of the AC power supply 7. By controlling the lighting control unit 6 to start the switching operation by the control unit 2, it is possible to reduce stress on the light source 8 and the AC power supply 7.

  In the present embodiment, an n-channel IGBT is used as the switching element, but a field effect transistor (FET) may be used.

A lighting control device for dimming 1a, 1b transistor 2 switching control unit 3 smoothing unit 4 current value measuring unit 5 phase control unit 6 lighting control unit 7 AC power source 8 light source

Claims (1)

A transistor that is inserted into a power supply path that connects the AC power source and the light source, and switches a sine wave AC from the AC power source
A switching controller for controlling on / off of the transistor;
A smoothing unit that outputs an alternating voltage obtained by smoothing a voltage switched by the transistor to the light source;
A current value measuring unit for measuring an output current value of the transistor;
Phase control of the triac connected in parallel with the transistor to control the lighting power of the light source,
When the output current value measured by the current value measurement unit is greater than or equal to a predetermined threshold in a state where the switching control unit performs a switching operation at the start of lighting of the light source, the switching control unit A lighting control unit that stops the switching operation, controls the phase control of the triac by the phase control unit, and controls to continue the switching operation by the switching control unit when the output current value is less than a predetermined threshold value. and,
Measuring means for measuring the elapsed time from the end of lighting of the light source,
The lighting control unit causes the phase control unit to perform phase control of the triac when the elapsed time is longer than a predetermined time at the start of lighting of the light source, and when the elapsed time is shorter than the predetermined time, A lighting control device for dimming, wherein a switching operation is performed by a switching control unit .

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