JP5243769B2 - Dimming control system - Google Patents

Description

  The present invention relates to a dimming control system that controls lighting of a light source with electric power obtained by superimposing an AC operating voltage and a rectangular wave control voltage.

  Conventionally, in a dimmer for dimming a light source, the AC power source is turned on / off with a rectangular wave, and the pulse duty of the rectangular wave is controlled to control the on-time of the AC power source applied to the light source for dimming What is controlled is known. For example, in Patent Document 1, a trigger signal is given to a switching element provided between an AC power source and a light source, and switching is performed in a preset time division period, whereby the connection between the light source and the AC power source is changed to a rectangular wave. A dimmer that performs dimming control by turning it on and off is shown.

However, in such a dimmer, when a plurality of power supply circuits that respectively supply lighting power to a plurality of light sources are provided, the on-duty rising timing of the rectangular wave in each power supply circuit is substantially the same. Therefore, the inrush current is concentrated in the commercial power supply facility that supplies power to each power supply circuit. Therefore, it is necessary to increase the power supply capacity, and the power supply efficiency is likely to decrease. In addition, radio noise is likely to occur when the rectangular wave rises.
JP 2007-128669 A

  The present invention has been made to solve the above-described problem, and a plurality of power supply circuits that are supplied with power from a commercial power source that controls lighting by turning on and off an alternating current power supply with a rectangular wave to a plurality of light sources, respectively. It is an object of the present invention to provide a dimming control system capable of improving power supply efficiency by preventing inrush currents based on rectangular waves of each power supply circuit from being concentrated.

In order to achieve the above object, the invention of claim 1 supplies a plurality of light sources, and lighting power formed by superimposing a sine wave operating voltage and a rectangular wave control voltage to each of the light sources. A dimming control system comprising a plurality of power supply circuits that are supplied with power from a commercial power source, wherein at least a rectangular wave of a control voltage in one power supply circuit rises between the plurality of adjacent power supply circuits. Control means for controlling a plurality of power supply circuits is provided so that the timing is different from that of other power supply circuits.

Further, in the claim 1 dimming control system according to said control means, of the two power supply circuits having a different rising timing of the rectangular wave having the off-duty, the rise of the rectangular wave in one of the power supply circuit Is the time of the zero crossing of the AC waveform of the operating voltage, and the rising timing of the rectangular wave in the other power supply circuit is the time when the period corresponding to the off-duty of the rectangular wave has elapsed from the zero crossing point. To control.

  According to the first aspect of the present invention, the rectangular waves of the control voltages in the plurality of power supply circuits do not rise at the same timing, and the inrush current due to the rectangular waves is dispersed, so that the maximum supply current of the commercial power supply is reduced. In addition, the use of power is leveled in time, and power supply efficiency is improved.

Further, according to the invention of claim 1, further concentration of the rush current by the square wave of the two power supply circuits are further reduced, the power efficiency is further improved.

  Hereinafter, a dimming control system (hereinafter referred to as the present system) according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the present system includes a plurality of light sources 10, a plurality of power supply circuits 20 that supply lighting power to the light sources 10, and a system control unit (control means) 30 that controls the entire system. A communication path 40 that connects the system control unit 30 and the plurality of power supply circuits 20 wirelessly. In addition, operating power is supplied to each power supply circuit 20 via a power supply line 51 from a main power supply unit 50 that supplies power from a commercial power supply in a house or the like. The communication path 40 may be a wired transmission path.

  The light source 10 is an illuminating lamp that is turned on by the power supply circuit 20 and is dimmed and controlled by the system control unit 30. The light source 10 can be an incandescent bulb, a fluorescent lamp, an LED, or the like.

  The power supply circuit 20 includes an AC power supply unit 21, a setting unit 22, a voltage control unit 23, a voltage superimposing unit 24, and a filter unit 25. The AC power supply unit 21 is an AC power supply that supplies the voltage superimposing unit 24 with a sine wave operating voltage V1 having a waveform pattern that alternately shows positive and negative values. The setting unit 22 sets the dimming rate of the light source 10 based on the dimming control signal from the system control unit 30, and sets the rise time of the rectangular wave of the control voltage V2 of the voltage control unit 23. The voltage control unit 23 generates a rectangular wave control voltage V2 having a frequency f based on the dimming rate and the rise time set by the setting unit 22, and controls the lighting of the light source 10 with the control voltage V2. The lighting control by the voltage control unit 23 is performed by controlling the pulse width of the rectangular wave of the control voltage V2 based on the dimming rate set by the setting unit 22. The voltage superimposing unit 24 superimposes the operating voltage V1 and the control voltage V2 and outputs a superimposed output voltage V3. The filter unit 25 smoothes the superimposed output voltage V3 from the voltage superimposing unit 24, and outputs a lighting voltage V4 for lighting the light source 10. The AC power supply unit 21 is supplied with operating power from the main power supply unit 50.

  The system control unit 30 includes an operation unit 31 and a wireless communication unit 32. The operation unit 31 is used by the user to designate the dimming rate of each light source 10 and the rise time for determining the rise timing of the rectangular wave in each power supply circuit 20. In addition, the dimming system number of each power supply circuit 20 is stored in advance. In response to an instruction from the operation unit 31, the system control unit 30 controls the plurality of power supply circuits 20 so that the timing of the rising of the rectangular wave of the control voltage in at least one power supply circuit 20 is different from that of the other power supply circuits 20. To do. The wireless communication unit 32 performs dimming control for dimming control of the light source 10 based on the dimming rate specified by the operation unit 31 and the rising time of the rectangular wave of the power supply circuit 20 corresponding to each dimming system number. A dimming control signal including a rate signal, a rise time signal, and a dimming system number is formed, and the dimming control signal is transmitted to the power supply circuit 20 corresponding to each dimming system number. Various control processes performed by the system control unit 30 are embodied by a CPU or the like. Further, DMX (Digital Multiplex), which is a protocol for performing data communication between lighting equipments, is used for transmission of the dimming control signal from the system control unit 30. For this reason, the system control unit 30 converts the dimming control signal including the dimming rate and the rise time specified by the operation unit 31 into DMX data, and transmits the DMX data from the wireless communication unit 32.

  As shown in FIG. 2, the voltage superimposing unit 24 in the power supply circuit 20 includes transistors Q1 and Q2 as semiconductor switching elements. As the switching element, a MOSFET, a bipolar transistor, a diode, or the like can be used. The filter unit 25 is a smoothing filter composed of a low-pass filter having the same choke coils L1 and L2 and an electrolytic capacitor C1, and the choke coils L1 and L2 are connected to the emitters of the transistors Q1 and Q2, respectively. The terminals on the output side of L1 and L2 are terminated with a capacitor C1. The filter unit 25 smoothes the superimposed output voltage V3 of the voltage superimposing unit 24 and outputs a lighting voltage V4.

  The sine wave operating voltage V1 shown in FIG. 3A is applied to the collectors of the transistors Q1 and Q2 of the voltage superimposing unit 24, and each base thereof is formed by the voltage control unit 23 in FIG. The rectangular wave control voltage V2 shown in b) is input. As a result, as shown in FIG. 3C, the output voltage of each emitter of the transistors Q1 and Q2 has a waveform in which the operating voltage V1 of the sine wave is turned on and off by the rectangular wave of the control voltage V2, and the sine wave A superimposed output voltage V3 in which rectangular waves of the operating voltage V1 and the control voltage V2 are superimposed is output. Here, the superposition of the operating voltage V1 and the control voltage V2 means that the operating voltage V1 is switched on and off by a rectangular wave of the control voltage V2, and the output that is turned on and off is the superimposed output voltage V3. It becomes. The superimposed output voltage V3 is input to the filter unit 25.

  The superimposed output voltage V3 input to the filter unit 25 is obtained by smoothing the superimposed rectangular wave by the filter unit 25. The output of the filter unit 25 is higher than the operating voltage V1, as shown in FIG. The lighting voltage V4 decreases in level. The smoothed lighting voltage V4 is applied to the light source 10 to turn on the light source 10. When the superimposed output voltage V3 is smoothed by the filter unit 25, the frequency component of the rectangular wave superimposed on the lighting voltage V4 is filtered and reduced by the characteristics of the low-pass filter of the filter unit 25.

  As illustrated in FIG. 4, the setting unit 22 includes a wireless communication unit 26, a rising setting unit 27, and a control voltage determination unit 28. In the setting unit 22, a dimming system number assigned in advance by an address or the like for each power supply circuit 20 is set. The dimming system number can be set by detecting the dimming system number included in the dimming control signal transmitted from the system control unit 30 to each power supply circuit 20. The user can set in advance by the provided dip switch. The wireless communication unit 26 receives the DMX data transmitted from the system control unit 30 via the wireless communication path 40 and demodulates the dimming control signal based on the received DMX data. In addition, the wireless communication unit 26 sets the dimming rate specified by the operation unit 31 from the dimming rate signal, the dimming system number, and the rise time signal included in the demodulated dimming control signal, and the own power supply circuit 20 The rise time corresponding to is detected, and this rise time is input to the rise setting unit 27.

  Based on the rise time detected by the wireless communication unit 26, the rise setting unit 27 sets the rise time that is the rise timing of the rectangular wave having the frequency f of the control voltage V2. The rise time is set by, for example, detecting the level of the sine wave operating voltage V1 at the rise setting unit 27 and using a certain value of the sine wave operating voltage V1 as a reference point (for example, a zero cross point (FIG. 8 (a))), and the rise time can be determined based on this reference point. At this time, the rise setting unit 27 can be provided with a volume or the like, and the user can set the rise time individually in advance.

  Based on the dimming rate set by the radio communication unit and the rise time set by the rise setting unit 27, the control voltage determination unit 28 controls the dimming rate and rise time of the rectangular wave having the frequency f of the control voltage V2. The determined dimming rate and the set value of the rise time are input to the voltage controller 23 to control the voltage controller 23.

  The voltage control unit 23 generates a rectangular wave having a set rise time based on the set values of the rise time and dimming rate determined by the control voltage determination unit 28, and is formed based on the rectangular wave. A control voltage V2 is generated. Further, the voltage control unit 23 determines the rectangular wave pulse duty of the control voltage V <b> 2 based on the set value of the dimming rate determined by the control voltage determination unit 28. The determination of the pulse duty of the rectangular wave is performed by adjusting the width w of the on-duty of the rectangular wave having the period T (frequency f = 1 / T) as shown in FIG. That is, the voltage control unit 23 controls the control voltage V2 by changing the on-duty width w of the rectangular wave in accordance with the set dimming rate, and performs dimming control of the light source 10.

  In the present system configured as described above, the user determines the dimming rate and the rising timing of the rectangular wave for the power supply circuit 20 of each dimming system number by operating the operation unit 31 in the system control unit 30. When each set value of the rise time is instructed, a dimming rate signal based on this instruction, a rectangular wave rise time signal, and a dimming control signal including a dimming system number are transmitted from the wireless communication unit 32 via the communication path 40. The data is transmitted to the wireless communication unit 26 of the setting unit 22 of each power supply circuit 20. The setting unit 22 of each power supply circuit 20 detects the dimming system number based on the dimming control signal received by the wireless communication unit 26 and sets the dimming rate and the rise time designated by the own power supply circuit 20. .

  Here, there are shown a case where the rising time of the rectangular wave in each power supply circuit 20 is set to be different from each other by the operation unit 31 and a case where the rising time of the rectangular wave in each conventional power supply circuit 20 is set to be the same. 6 and with reference to FIG. Here, the dimming rate of each power supply circuit 20 specified by the operation unit 31 is constant.

  As shown in FIGS. 6A, 6B, and 6C, in the power supply circuit 20 of the present system, each control voltage V2 from the first power supply circuit and the second power supply circuit to the nth power supply circuit has a rectangular shape. Wave rise times t1, t2, and tn are set to be different from each other. At this time, as shown in FIGS. 6D, 6E, and 6F, the inrush current in each power supply circuit 20 flows in a distributed manner corresponding to the rising times t1, t2, and tn of the rectangular wave. It has the same peak current value ia. Here, assuming that the sum of the inrush currents of the power supply circuits 20 is the operating current I of the main power supply unit 50, the operating current I is the sum of the inrush currents dispersed in time as shown in FIG. It becomes. When the peak current value of the operating current I is Ia, the peak current value Ia is lower than the peak current value Ib (see FIG. 7) when the rising timing is the same. Therefore, the main power supply unit 50 can reduce the maximum supply current that can be supplied by decreasing the peak current value. In addition, since the current flow in the main power supply unit 50 is dispersed and the time zone during which no current flows is reduced, the current flow can be leveled temporally. Thereby, the power supply efficiency of the main power supply unit 50 is improved. In addition, since the peak current value of the operating current I can be reduced, noise radiated from the power supply line or the like based on the current of the frequency component of the rectangular wave included in the operating current I is reduced, and peripheral electronic devices, etc. It is possible to suppress the interference of radio noise with the antenna.

  On the other hand, when the rise time of the rectangular wave in each power supply circuit 20 is set to be the same, as shown in FIGS. 7A, 7B, and 7C, the first power supply circuit and the second power supply circuit are connected to the nth. Since each control voltage V2 up to the power supply circuit has the same rise time for each rectangular wave, the timing of the inrush current due to the rectangular wave in all the power supply circuits 20 matches. For this reason, as shown in FIG. 7D, the total operating current I of the currents of the power supply circuits 20 flowing through the main power supply unit 50 rushes into a rectangular wave on-duty time zone in each power supply circuit 20. The peak current value Ib of the current increases to approximately n times (n is the number of power supply circuits 20) the peak current value ia of the inrush current of each power supply circuit 20 at the same timing. That is, in the main power supply unit 50, power is consumed only in the same rising on-duty time period, so that the peak current value becomes larger as Ib than Ia. For this reason, it is necessary to increase the maximum supply current of the main power supply unit 50, and the off-duty is all in the same time zone, so that the time zone in which no current flows concentrates, and the power consumption in the main power supply unit 50 is temporal. Therefore, power efficiency is lowered. Further, the increase in the peak current value of the operating current I increases the level of radio noise, and the influence of radio noise on peripheral electronic devices and the like also increases.

  As described above, according to the dimming control system of the present embodiment, the rectangular waves of the control voltage V2 in the plurality of power supply circuits do not rise at the same timing, so that the inrush current of each power supply circuit 20 is avoided. Compared with the case where the rising timing is the same, the peak current value of the operating current I of the main power supply unit 50 on the power supply side of the commercial power supply can be reduced. As a result, the maximum supply current of the main power supply unit 50 can be reduced, and concentration of the time zone in which no current flows is reduced, so that the use of power is leveled in time, and the main power supply unit 50 Power supply efficiency is improved. In addition, the maximum specification rating (power value, current value, etc.) of the electrical components such as breakers and fuses provided on the main power supply unit 50 side can be reduced.

  Further, due to the dispersion of the inrush current, the high-frequency current component based on the frequency of the rectangular wave flowing through the main power supply unit 50 is also dispersed, and the current value is also reduced. Thereby, the noise of the frequency of the rectangular wave radiated | emitted from the wiring etc. of the electric power feeding line 51 which connects the main power supply part 50 and each power supply circuit 20 can be reduced, and the other existing near each power supply circuit 20 It is possible to reduce interference of radio noise to electronic devices and wireless devices.

  Next, a dimming control system according to a second embodiment of the present invention will be described with reference to FIGS. In this system, one of the two power supply circuits with different rectangular wave rising timings is at the time of zero crossing of the AC waveform of the operating voltage, and the other is a period corresponding to the off-duty of the rectangular wave from the zero crossing point. Control to be at the point of time. Other configurations are the same as those in the above embodiment.

  The system control unit 30 divides the power supply circuit 20 in this system according to the designation from the operation unit 31 when the dimming system number is an odd number and when it is an even number. The rising timing of each rectangular wave of the circuit 20 is set to be different from each other, and one is a time point of zero crossing of the AC waveform of the operating voltage V1, and the other is a period corresponding to the off-duty of the rectangular wave from the zero crossing point. Each power supply circuit 20 is controlled so that the time has elapsed. Here, both the odd-numbered and even-numbered rectangular waves of the power supply circuit 20 have a frequency of 32 kHz and an on-duty width w of 1/64 kHz. As shown in FIG. 8A, in the waveform of the operating voltage V1, a point where the value of the AC waveform of the sine wave changes from positive to negative or from negative to positive is defined as a zero cross point p, as shown in FIG. 8B. In addition, the rectangular wave of the control voltage V2 of the odd-numbered power supply circuit 20 is set to rise at the zero-cross point p, and as shown in FIG. The wave is set to rise from the zero-cross point p when a period corresponding to the off-duty of the rectangular wave (here, the off-duty period is 1/64 kHz) has elapsed. That is, in the even-numbered power supply circuit 20, the first half of one period of the rectangular wave is set as an off duty, and the latter half is set as an on duty. As a result, each of the odd-numbered power supply circuit 20 and the even-numbered power supply circuit 20 has their rectangular wave rising edges shifted by a time of 1/64 kHz. In each of the power supply circuits 20 divided, the inrush current and the power used are not concentrated but distributed.

  Here, the setting of the on-duty of the rectangular wave of the control voltage V2 will be described. The on-duty ratio corresponding to the dimming rate set by the operation unit 31 is tabulated in advance as shown in Table 1 below and stored in the voltage control unit 23. Therefore, the voltage control unit 23 automatically selects the on-duty ratio (%) from the table of Table 1 based on the dimming rate determined by the control voltage determination unit 28, and sets the dimming The on-duty width is controlled to match the rate. If the power supply circuit 20 is not connected to the system control unit 30 via the communication path 40, a dimming rate adjusting volume or the like is provided in the setting unit 22 to adjust the dimming rate individually. Good.

  Here, for example, when the user sets the dimming rate to 5% using the operation unit 31 and instructs an odd dimming system number, the on-duty ratio at the dimming rate of 5% is 14% from Table 1. From FIG. 9, the waveform of the rectangular wave with the frequency of the control voltage V2 in the power supply circuit 20 being 32 kHz has a width of one rectangular wave (period T1) of 1/32000 (s) and an on-duty width. w1 becomes 1/32000 × 0.14 (s). Thus, the on-duty width is easily calculated from Table 1 based on the dimming rate specified by the user, and the light source 10 is dimmed and controlled by controlling the on-duty width. Even when the dimming system number is an even number, the on-duty width can be obtained by calculation using the same table as in Table 1.

  When the ratio of the on-duty of the rectangular wave is 14% as described above, the timing of the rising of the rectangular wave in each of the power supply circuits 20 having the dimming system number of the odd number and the even number is shifted from each other by the off duty, The case where the rising timings of both rectangular waves are the same will be described with reference to FIGS. Here, since the on-duty ratio is set to 14%, which is smaller than 50%, as shown in FIGS. 10A and 10B, the rising timing of the rectangular wave in the odd-numbered power supply circuit 20 and the even number The rising timing of the numbered rectangular wave is shifted by the off-duty time. Therefore, as shown in FIG. 10 (c), the operating current I of the main power supply unit 50 is determined by the fact that the on-duty periods of the rectangular waves of the control voltage V2 in the odd-numbered and even-numbered power supply circuits 20 do not overlap each other. Compared with the peak current value Id (see FIG. 11) when the peak current value Ic is the same as the rising timing of the rectangular wave of all the power supply circuits 20, the number of power supply circuits of odd number and even number is about half. Therefore, the power efficiency of the main power supply unit 50 is improved.

  In contrast, as shown in FIGS. 11A, 11B, and 11C, when the rising timings of the odd-numbered power supply circuit 20 and the even-numbered power supply circuit 20 are the same, the peak current value Id of the operating current I is Since the sum of the peak current values of the individual power supply circuits 20 is approximately doubled as compared with the case where the rising timing is shifted, and the power supply efficiency is deteriorated because the power supply off time is long. .

  Further, the odd number and even number control in the power supply circuit 20 when the dimming rate of the power supply circuit 20 of the odd number and even number of the dimming system number is increased and the on-duty ratio is 50% or more, respectively. The waveform of the voltage V2 is shown in FIGS. In the odd-numbered power supply circuit 20 and the even-numbered power supply circuit 20, the inrush currents are dispersed as shown in FIG. 12C by shifting the rising edges of the rectangular waves by the off-duty time. Thus, as described above, the operating current I of the main power supply unit 50 has the peak current value Ie compared to the case where the rising timing of the rectangular wave of the odd-numbered power supply circuit 20 and the even-numbered power supply circuit 20 is the same. Since the time period during which current does not flow is eliminated, the power supply efficiency of the power supply unit 50 is improved.

  As described above, according to the dimming control system of the second embodiment, in the two power supply circuits 20 having the different rising timings of the rectangular waves, the rising timings of the rectangular waves of each other correspond to the off-duty period. Therefore, the concentration of the inrush current due to the rectangular wave of the power supply circuit 20 is further reduced. As a result, the inrush currents are surely distributed and the peak current value flowing through the power supply unit 50 is further reduced, and the time period during which no current flows is reduced and the use of power is further leveled. The power efficiency of 50 is further improved.

  In addition, this invention is not limited to the structure of said various embodiment, A various deformation | transformation is possible suitably in the range which does not change the meaning of invention. Although the case where the frequency of the rectangular wave is 32 kHz has been described in the above embodiment, the frequency of the rectangular wave is freely selected without being limited thereto. In addition, the rise time of the rectangular wave is divided into two cases where the dimming system number is odd and even, and the rise time is shifted by the off-duty time. It can also be shifted, and can also be shifted for each dimming system number. In addition, by setting the rising timing of the rectangular wave of adjacent power supply circuits to be different from each other, high-frequency noise or rectangular wave frequency generated at the rising edge of the rectangular wave due to the nonlinear characteristics of the switching element Therefore, it is possible to suppress the increase in radio noise by synergizing these high frequency noises and harmonic noises between adjacent ones. Moreover, although wireless communication was used for the communication path between each power supply circuit and the system control unit, power line carrier communication using a wired transmission line or AC power wiring that supplies power to each power supply circuit in common ( PLC) can also be used.

The block diagram of the illumination control system which concerns on the 1st Embodiment of this invention. The block diagram of the power supply circuit of the said system. (A) is a figure which shows the alternating current power supply voltage waveform of the said power supply circuit, (b) is a figure which shows the control voltage waveform of the circuit, (c) is a figure which shows the superimposed output voltage waveform of the circuit, (d) is the figure The figure which shows the filter part output waveform of a circuit. The block diagram of the setting part of the said power supply circuit. The figure explaining the control voltage rectangular wave of the said power supply circuit. (A) is a figure which shows the control voltage waveform of the 1st power supply circuit in the said system, (b) is a figure which shows the control voltage waveform of a 2nd power supply circuit, (c) is a figure which shows the control voltage waveform of an nth power supply circuit (D) is a diagram showing an inrush current waveform of the first power supply circuit, (e) is a diagram showing an inrush current waveform of the second power supply circuit, (f) is a diagram showing an inrush current waveform of the nth power supply circuit, g) illustrates the operating current of the main power supply unit. (A) is a figure which shows the control voltage waveform of a 1st power supply circuit in case the timing of a rising of a rectangular wave is the same, (b) is a figure which shows the control voltage waveform of a 2nd power supply circuit, (c) is an nth power supply circuit The figure which shows the control voltage waveform of (d), The figure explaining the operating current of a main power supply part. (A) is a figure which shows the operating voltage waveform in the illumination control system which concerns on the 2nd Embodiment of this invention, (b) is a figure which shows the control voltage waveform in the odd-numbered power supply circuit of the system, (c) is an even number The figure which shows the control voltage waveform in the power supply circuit of a number. The figure which shows the on-duty waveform of the control voltage in case the frequency of the rectangular wave of the said power supply circuit is 32 kHz and the light control rate is 5%. (A) is a figure which shows the control voltage waveform of the odd-numbered power supply circuit in the dimming rate 5% of the said system, (b) is a figure which shows the control voltage waveform of the even-numbered power supply circuit, (c) is a main power supply part The figure explaining the operating current of. (A) is a diagram showing the control voltage waveform of the odd-numbered power supply circuit when the rising timing of the rectangular wave is the same; (b) is a diagram showing the control voltage waveform of the even-numbered power supply circuit; The figure explaining the operating current of the main power supply part which supplies electric power to each power supply circuit. (A) is a figure which shows the control voltage of the said odd-numbered power supply circuit in case the on-duty ratio of a rectangular wave is 50% or more, (b) is a figure which shows the control voltage of an even-numbered number, (c) is a main power supply part The figure explaining the operating current of.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light source 20 Power supply circuit 30 System control part (control means)
40 Communication path p Zero cross point V1 Operating voltage V2 Control voltage

Claims (1)

A plurality of light sources, and a plurality of power supply circuits supplied with power from a commercial power source, each of which supplies lighting power obtained by superimposing a sine wave operating voltage and a rectangular wave control voltage to each of the light sources. A dimming control system comprising:
Control means for controlling the plurality of power supply circuits so that the rising timing of the rectangular wave of the control voltage in one power supply circuit differs from that of the other power supply circuit between at least the plurality of adjacent power supply circuits. ,
The control means, among the two power supply circuits, the rising timing of the rectangular wave having an off duty is different, the rising timing of the rectangular wave in one power supply circuit is the time of zero crossing of the AC waveform of the operating voltage, A dimming control system , wherein the timing of rising of the rectangular wave in the other power supply circuit is controlled to be a point in time when a period corresponding to the off-duty of the rectangular wave has elapsed from the zero cross point .

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