JP3928133B2 - Incandescent light dimmer - Google Patents

Description

  The present invention relates to an incandescent lamp dimming device suitable for lighting such as a studio, a theater, and a stage.

  In general, dimming lighting is indispensable in this kind of stage lighting and the like for the purpose of enhancing the effect of production. Here, in the case of using an incandescent lamp for illumination, in order to vary the electric power supplied to the incandescent lamp according to the dimming level, for example, on the line of the AC power source 1 as shown in FIG. A pair of thyristors 2 and 3 are provided in reverse parallel connection, and phase control is performed such that these thyristors 2 and 3 are fired at a timing according to the dimming signal level after detecting zero-cross in every half cycle. This is realized by supplying electric power having a waveform as shown in FIG.

  In such phase control of the thyristors 2 and 3, since the current changes sharply, di / dt at the time of ignition is large, so that high frequency noise (RF noise) is generated. In addition, there is a problem that acoustic noise is generated in the filament portion of the incandescent lamp 4 as a load.

  Therefore, in practice, as shown in FIG. 14A, a reactor L is inserted in series with the thyristors 2 and 3, and this reactor L causes the current to flow as shown in FIG. A method is adopted in which the rise (when the thyristors 2 and 3 are ignited) is made gentle. However, the reactor L is large in size and expensive, and the reactor L itself generates a noise that becomes acoustic noise, impedes a quiet environment and becomes unsuitable as lighting for a studio, a stage, and the like.

For this reason, Patent Document 1 and Patent Document 2 show a method for performing current rising and falling slope control as a method for reducing noise. Specifically, instead of a thyristor, tilt control can be performed using a switching element such as a transistor, FET (field effect transistor), or IGBT (gate insulating bipolar transistor).
U.S. Pat. No. 4,975,629 US Pat. No. 4,823,069

  However, the switch elements used for these inclination controls are expensive and have a drawback of large heat generation because of high on-resistance. Further, these switch elements have an overcurrent withstand capability smaller than that of the thyristor, and therefore may be destroyed by an overcurrent in a low resistance state when the power is turned on. That is, in the case of an incandescent lamp load, when the filament is cold as when the power is turned on, the resistance value is low and a current several times to 10 times the rated current flows for several cycles. Does not withstand such an inrush current. However, if the supply current is limited in order to prevent destruction of these switch elements, sufficient power cannot be supplied to the incandescent lamp, and the rise of the incandescent lamp is delayed. In this case, the stage effect cannot be exhibited freely as stage lighting or the like, which is inappropriate.

  In addition, this type of device requires protection when the output is short-circuited, but conventionally, only an overcurrent protection breaker is provided on the input side.

  The object of the present invention is to supply sufficient electric power to the incandescent lamp through the main switch circuit side of the thyristor to the incandescent lamp without worrying about the overcurrent withstand capability, so that the rise of the luminous flux is not delayed. It is to provide an incandescent light dimmer.

  An incandescent lamp dimming device according to the present invention includes a main switch circuit by a thyristor that is connected to an AC power supply line for an incandescent lamp and is phase-controlled every half cycle; and an auxiliary device that includes a switching element connected in parallel with the main switch circuit. A switch circuit; auxiliary switch circuit control means for linearly operating the switching element of the auxiliary switch circuit immediately before the thyristor is fired; monitoring means for monitoring the output current to the incandescent lamp; Timing signal generating means for generating and outputting a timing signal for igniting a thyristor in the main switch circuit, and for outputting the timing signal when an output current of a predetermined value or more flows in a linear operation of the switching element; It is characterized by being.

  According to the present invention, most of the ON section of each half cycle is handled by the main switch circuit using a thyristor having a low ON resistance, so that heat generation is reduced, and the steep rising portion is controlled by the auxiliary switch circuit control means. Since the switching element of the auxiliary switch circuit that operates linearly takes charge, it rises in an inclined state and shifts to the ON section of the thyristor, which solves the problem of generating acoustic noise due to roaring.

  Furthermore, when the filament resistance of the incandescent bulb is small, such as when the power is turned on, the output current increases. Therefore, when the current exceeding a certain value is monitored by the monitoring means, the timing signal generating means advances the timing signal and outputs it. Instead of the linear operation of the switching element, the ignition of the thyristor is accelerated. Accordingly, sufficient power can be supplied to the incandescent lamp even during the transition period through the main switch circuit side by the thyristor without worrying about overcurrent withstand capability, and the rise of the luminous flux can be prevented from being delayed.

  First, the configuration assumed in the present invention will be described with reference to FIGS.

  A main switch circuit 15 in which two thyristors 13 and 14 are connected in antiparallel is connected between the AC power supply 11 and the incandescent lamp 12. The gates of the thyristors 13 and 14 are connected to voltage dividing trigger circuits 16 and 17 including photothyristors PTH1 and PTH2 constituting one of photocouplers and formed by voltage dividing resistors R11, R12, R21 and R22. (However, the resistors R11 and R12 are not essential, and may be omitted as shown in the following embodiments, or may be replaced with other elements). Further, an auxiliary switch circuit 20 including a full-wave rectifier circuit 18 and a switching element such as an IGBT 19 is connected in parallel with the main switch circuit 15.

  Further, a power transformer 21 for monitoring the input voltage is connected to the AC power source 11, zero cross is detected every half cycle based on the output of the power transformer 21, and dimming input via the transmission line A timing generator (timing signal generating means) 22 is provided for generating and outputting a timing signal for performing phase control of the thyristors 13 and 14 at a timing according to the signal level. The timing generator 22 performs phase control of the thyristors 13 and 14 and thus ignition control through the light emitting diodes LED1 and LED2 corresponding to the photothyristors PTH1 and PTH2 constituting the photocoupler. More specifically, as shown in FIG. 2, the timing generator 22 includes a zero-cross detection circuit 23 and a counter 24 that counts an elapsed time after the zero-cross detection.

  In addition, a monitoring transformer (monitoring means) 25 is provided to monitor the output voltage to the incandescent lamp 12. While receiving feedback of the output voltage monitored by the monitoring transformer 25, the IGBT 19 of the auxiliary switch circuit 20 An inclination control unit (auxiliary switch circuit control means) 26 for controlling the operation is provided. As shown in FIG. 3, the slope control unit 26 includes a slope function generation unit 27 to which a signal from the timing generation unit 22 is input, an output of the slope function generation unit 27, and an output fed back from the monitoring transformer 25. A comparison control unit 28 to which a voltage is input, and an appropriate base voltage is input to the base of the IGBT 19 at an appropriate timing so that the voltage increases linearly with a linear function voltage change rate in an analog manner. It is something to be made.

  In such a configuration, the operation will be described with reference to the timing chart shown in FIG. First, the output of the power transformer 21 is input to the timing generator 22, and the zero-cross point is detected by the zero-cross detection circuit 23. Each time the zero cross point is detected, the counter 24 measures the time corresponding to the level of the dimming signal and outputs the time to the subsequent tilt control unit 26. The thyristor firing pulses as shown in FIG. This output is performed through a photocoupler. Based on the output signal from the timing generator 22, the slope controller 26 outputs a ramp function waveform at the slope function generator 27, compares it with the output voltage at the comparison controller 28, and generates a matching base signal of the IGBT 19. Output to base. Such a base signal for the IGBT 19 serves to linearly operate the IGBT 19 as shown in FIG. 4B. It operates only in the section immediately before the thyristor is fired. As a result, the output voltage to the incandescent lamp 12 is the sum of the voltage due to the linear operation of the IGBT 19 and the voltage due to the alternate firing of the thyristors 13 and 14 as shown in FIG.

  Therefore, most of the ON section in each half cycle is handled by the thyristors 13 and 14 having a low ON resistance, so that the heat generation is small and a compact configuration is possible. Further, only the steep rising portions of the thyristors 13 and 14 are in charge of the linear operation of the IGBT 19, and the output voltage rises in a state in which the output voltage is appropriately inclined. Therefore, it is suitable as dimming lighting for the stage. Incidentally, the interval T during which the IGBT 19 is linearly operated is preferably about 400 μs as the time during which the noise noise of the lamp is not generated. In addition, the control for linearly operating the IGBT 19 is based on feedback of the output voltage detected by the monitoring transformer 25, so that it does not fluctuate depending on the load (incandescent lamp 12) as in the case of current, and is stable. And proper control becomes possible.

  In the above configuration, the main switch circuit 15 is configured by the two thyristors 13 and 14 connected in reverse parallel. However, the main switch circuit 15 may be configured by one bidirectional thyristor (triac), and the auxiliary switch circuit. The 20 switching elements are not limited to the IGBT 19 and may be ordinary transistors, FETs, or the like. The timing generator (timing signal generator) 22 outputs an ignition pulse to the thyristors 13 and 14, and the slope controller (auxiliary switch circuit controller) 26 outputs a gate signal to the IGBT (switching element) 19. It is necessary that the timing to be in the above-described relationship, but the configuration for obtaining such timing can be variously modified. For example, a signal may be output from the auxiliary switch circuit control means to the timing signal generation means in response to the stop and timing of the gate signal. Such means are often configured using a microcomputer, and can be appropriately designed by those skilled in the art. These points are the same in the following.

  Next, modified examples of the above configuration will be described with reference to FIGS. The same parts as those shown in the above configuration are indicated by the same reference numerals (the same applies hereinafter). In this configuration, in addition to the above-described configuration, as a countermeasure against a short circuit, a differentiation circuit (monitoring means) 30 that detects a time change of the output current with respect to the incandescent lamp 12 through the detection winding 29 is provided, and timing is generated by the output of the differentiation circuit 30. The operation control of the unit 22, and thus the thyristors 13 and 14, is performed. The other configuration is the same as the configuration described above.

  In such a configuration, the time change of the output current at the time of the linear operation of the IGBT 19, that is, the value of di / dt detected by the differentiating circuit 30 is the same figure in the normal load shown by the broken line in FIG. The value is relatively small as shown by a broken line in a), but the value of di / dt is large as shown by the solid line in FIG. The threshold dTH can be used to distinguish between the two.

  Therefore, when a short circuit occurs under the same controlled condition as in the case of the above configuration, a differential output greater than or equal to the threshold value dTH is output from the differential circuit 30 during the linear operation of the IGBT 19, as shown in FIG. If it is output, the timing generator 22 determines that a short circuit has occurred and stops the output of the subsequent thyristor firing pulse. Therefore, the thyristors 13 and 14 do not conduct, and the danger associated with a short circuit is avoided. In this case, the operator is notified of the occurrence of an abnormality due to a short circuit via the transmission line, and the cause of the operation stop is clarified.

  As described above, according to this configuration, the occurrence of a short circuit can be reliably detected at a stage where the IGBT 19 is in a linear operation, and the output voltage is low and the short circuit current is relatively small. In particular, it is possible to cope with the short circuit without causing the thyristor 13 or 14 to be ignited when the short circuit occurs, and the safety is high.

  In this way, since it is possible to take a countermeasure against short circuit without requiring a breaker, when constructing an illumination system, as shown in FIG. 8, the dimmers 31 having the above-described configuration are distributed and arranged for each incandescent lamp 12, The power line 32 and the transmission line 33 can be connected to the console 34, and the degree of freedom is increased.

  Next, an embodiment of the present invention will be described with reference to FIGS. The present embodiment is similar to the configuration assumed above, but in order to improve the startability, a detection winding 35 for monitoring the output current to the incandescent lamp 12 is provided as a monitoring means, and the value of the detected output current Accordingly, the operation of the timing generator 22, and thus the ignition operation of the thyristors 13 and 14 are controlled.

  In such a configuration of the present invention, in the steady state after the incandescent lamp 12 is warmed and stabilized, the operation is controlled under the timing chart as shown in FIG. Dimmable lighting with little heat generation is performed.

  Consider a case where the incandescent lamp 12 is turned on from a cold state. Under such circumstances, since the filament resistance of the incandescent lamp 12 is low, an output current of several times to several tens of times that in a steady state flows as shown in FIG. Here, when an output current of a certain value or more determined from the rated current of the IGBT 19 or the like is detected by the detection winding 35, the timing generator 22 advances the timing earlier than the normal time as shown in FIG. 11 (c). The fired ignition pulse is output to the thyristors 13 and 14 so that the thyristors 13 and 14 are fired early. Here, since the thyristors 13 and 14 have a large overcurrent withstand capability, the thyristors 13 and 14 are not destroyed by such a transient large current, and sufficient power is supplied to the incandescent lamp 12. As a result, the light quantity of the incandescent lamp 12 rises quickly even under low temperature conditions, which is preferable for producing the effect of production. Further, since the IGBT 19 having a small overcurrent withstand capability is protected by the conduction of the thyristors 13 and 14 before a current exceeding the rated current flows, the acoustic noise prevention effect can be sufficiently exerted after the transition to the steady state. .

  Further, a modification will be described with reference to FIG. This configuration is to avoid inconvenience when the load (incandescent lamp 12) is very small. First, consider a case where the load is very small in the configuration shown in FIG. In such a case, a trigger current sufficient for starting the thyristors 13 and 14 may not flow, and the thyristors 13 and 14 may not start. In this case, the current to the load flows through the voltage dividing trigger circuit 16 (or 17) consisting of the resistor R11 → the photothyristor PTH1 → the resistor R12 (or the resistor R21 → the photothyristor PTH2 → the resistor R22). Here, since these resistors R11, R12, R21, R22 and photothyristors PTH1, PTH2 form voltage dividing trigger circuits 16, 17, normally only a small current flows, so circuit components with a low power rating are used. Therefore, the rating may be exceeded. In order to prevent a current exceeding the rating from flowing, a sufficiently large rated component may be used as these resistors R11, R12, R21, R22, photothyristors PTH1, PTH2, etc., but this increases the size and cost. End up. Further, it is conceivable that a dummy resistor R3 is inserted in parallel with the load (incandescent lamp 12) as shown by a broken line in FIG. 1, but this causes the dummy resistor R3 to always consume wasteful power and generate heat. This is not preferable.

  Therefore, in this example, it is possible to cope with a case where the load is very small by simply devising the operation control of the IGBT 19 by the inclination control unit 26 without changing the circuit configuration shown in FIG. . For this reason, as described above, the IGBT 19 of the auxiliary switch circuit 20 is linearly operated immediately before the thyristors 13 and 14 are fired. Further, after a sufficient time has elapsed for the thyristors 13 and 14 to fire. Basically, the IGBT 19 is turned on again.

  This point will be described with reference to a timing chart shown in FIG. First, as in the case of the above-described embodiment, the base signal for linearly operating the IGBT 19 is given by the inclination control unit 26 in the section immediately before the thyristor firing. As a result, the IGBTs 19 are sequentially turned on. When the IGBTs 19 are saturated, a trigger is applied to the thyristor 13 or 14 by the voltage dividing trigger circuit 16 or 17 under the control of the timing generator 22 to cause the ignition operation. At the same time, the IGBT 19 is turned off. Then, when a time t1 sufficient for the thyristors 13 and 14 to fire has elapsed from the firing timing of the thyristors 13 or 14, the slope control unit 26 applies a base current so as to turn on the IGBT 19 again.

  According to such a control method, if the thyristor 13 or 14 is not ignited due to a very small load or the like, a current flows to the load side through the IGBT 19 that is turned on again. Become. Therefore, an excessive current does not flow through the voltage dividing trigger circuit 16 (or 17) consisting of the resistor R11 → the photothyristor PTH1 → the resistor R12 (or the resistor R21 → the photothyristor PTH2 → the resistor R22). Therefore, it is not necessary to use those having a large special rating as these resistors R11, R12, R21, R22, photothyristors PTH1, PTH2, etc., and it is not necessary to use dummy resistors. Considering the case where the load is large, the thyristor 13 or 14 is reliably fired, and the on-resistance of the thyristors 13 and 14 is lower than that of the IGBT 19, so that even if the IGBT 19 is turned on again, the current to the load Flows through the original thyristor 13 or 14 side. Therefore, when the load is large, the IGBT 19 having a small overcurrent withstand capability is protected by the conduction of the thyristors 13 and 14 before the current exceeding the rated current flows, so the low overcurrent withstand capability of the IGBT 19 is a problem. Don't be.

It is a circuit diagram which illustrates the composition assumed by the present invention. It is a block diagram of a timing signal generator. It is a block diagram of an inclination control part. It is a timing chart which shows operation. It is a circuit diagram which shows another example. It is explanatory drawing which shows the mode at the time of a short circuit. It is a timing chart which shows operation. It is a connection diagram which shows the example of distribution arrangement | positioning. It is a circuit diagram which shows the Example of this invention. It is a timing chart which shows operation at regular times. It is a timing chart which shows operation | movement of a low temperature transition period. It is a timing chart which shows another example. A prior art example is shown, (a) is a circuit diagram, (b) is a waveform diagram. Another example is shown, (a) is a circuit diagram, (b) is a waveform diagram. It is a connection diagram which shows the time of system configuration.

Explanation of symbols

11 AC power supply 12 Incandescent lamps 13 and 14 Thyristor 15 Main switch circuit 19 Switching element 20 Auxiliary switch circuit 22 Timing signal generating means 25 Monitoring means 26 Auxiliary switch circuit control means 30 Monitoring means 35 Monitoring means

Claims (1)

A main switch circuit with a thyristor connected on the AC power line to the incandescent lamp and phase controlled every half cycle;
An auxiliary switch circuit including a switching element connected in parallel with the main switch circuit;
Auxiliary switch circuit control means for linearly operating the switching element of the auxiliary switch circuit in a section immediately before the thyristor is fired;
Monitoring means for monitoring the output current for the incandescent lamp;
A timing signal for generating and outputting a timing signal for starting the thyristor in the main switch circuit in synchronization with an AC power supply, and for outputting a timing signal when an output current of a predetermined value or more flows in a linear operation of the switching element. Generating means;
An incandescent lamp light control device comprising:

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