JP5182765B2 - Transmission circuit, transmission method, and dimming information transmission circuit for lighting apparatus - Google Patents

Description

  The present invention relates to a transmission circuit, a transmission method, and a dimming information transmission circuit for a luminaire, which use a power line as a communication line to transmit a digital signal for controlling an electric device that is supplied with power from the power line. .

BACKGROUND ART Power line communication called PLC (Power Line Communication) is known as one that transmits and receives digital signals using a power line as a communication line. In this power line communication, it is not necessary to newly lay a cable for a communication line by using a power line, but data communication is performed by superimposing a modulation wave of several hundred kHz to several MHz on an alternating current. It has been pointed out that leaked radio waves interfere with wireless communication devices.
For example, Patent Document 1 discloses a technique in which a signal is not superimposed on an alternating current as a modulated wave when a power line is used as a communication line.
In the remote control device described in Patent Document 1, a device main body and an operation unit are connected in series via a single power / signal line between power supplies, and the presence / absence of one-side half wave of one cycle of an AC waveform. By sending a signal corresponding to 1 and 0 of the digital signal, the component costs of the transmission unit and the reception unit are reduced.

JP-A-5-276572

However, in the remote control device described in Patent Document 1, when the zero-cross detection unit detects a half cycle of the power source whose electric potential of the electric wire is higher than that of the signal line serving as the power source, the operation control unit is a semiconductor switch such as a transistor of the transmission unit. Since the potential of the power / signal line is changed by turning ON / OFF, it is considered that a delay occurs until the potential changes after the AC crosses zero.
This delay, when transmitting “0” of the digital signal, should remove all of the half cycle, but it causes a little current to flow after zero crossing. For example, as shown in FIG. In FIG. 8, it is worried that "W" will be supplied. Therefore, if a pulsed voltage is applied to the power line, it may cause high-frequency noise, or the pulsed voltage may be transmitted to the power source of the communication destination electrical device, causing malfunction of the electrical device. There is a fear.

  In the lighting device using the LED, the brightness of the LED is adjusted by increasing / decreasing the pulse width of the power supplied to the LED. Therefore, if a pulsed voltage leaks from the transmission circuit side to the power line, the power is supplied from the power line. The supplied circuit for controlling the brightness adjustment outputs noise to the LED, which may cause the LED to flicker.

Therefore, the present invention provides a transmission circuit and a transmission method that do not affect other devices while reliably transmitting a digital signal when transmitting a signal to a communication destination electrical device via a power line. Objective.
It is another object of the present invention to provide a dimming information transmission circuit for a lighting fixture with little flicker.

  The transmission circuit according to the present invention transmits digital signals H and L to an electric device as a communication destination through the power line in correspondence with the presence or absence of a half cycle of an AC positive voltage or negative voltage flowing through the power line. A zero-cross detection circuit that detects a zero-cross point at which alternating current flowing through the power line passes 0 V and outputs a zero-cross point signal; and based on the reception timing of the zero-cross point signal, to the communication destination electrical device A control circuit that outputs a removal signal instructing removal of half a cycle corresponding to a digital signal to be transmitted, that the removal signal has been received, and that a zero cross point at which AC flowing through the power line passes 0 V has been detected. Signal addition circuit that removes AC waveform for half cycle and transmits power to one or more electrical devices Characterized by comprising a.

  In the transmission circuit of the present invention, first, the zero cross detection circuit detects a zero cross point where the alternating current flowing through the power line passes 0 V and outputs a zero cross point signal. Next, based on the reception timing of the zero cross point signal, the control circuit outputs a removal signal instructing the removal of a half cycle corresponding to the digital signal transmitted to the communication destination electrical device. Then, on condition that the signal addition circuit has received the removal signal and that the zero crossing point at which the alternating current flowing through the power line passes 0V is detected, the alternating current waveform for half a cycle is removed to be one or more communication destinations. Power to other electrical equipment. In other words, the zero cross detection circuit finds the timing of the zero cross point that triggers the transmission of the digital signal, and the signal addition circuit detects the half cycle at the timing of the next zero cross point according to the half cycle removal instruction output by the control circuit. Therefore, the removal delay can be made small.

  Preferably, the control circuit delays the start of output of the removal signal from the received zero cross point signal, and sets the signal width of the removal signal to a time width including a zero cross point next to the zero cross point. By delaying the removal signal from the zero cross point signal, it is possible to prevent the zero cross point recognized by the control circuit from being mistaken as the zero cross point at which the signal addition circuit starts adding the digital signal. In addition, by setting the signal width of the removal signal to a time width that includes the zero cross point next to the zero cross point that the control circuit has triggered the transmission of the removal signal, the signal addition circuit can reliably ensure a half cycle from the next zero cross point. The digital signal can be added to the alternating current.

  It is desirable to provide a power supply circuit that generates a power supply necessary for each circuit from an alternating current flowing through the power line. Since the power supply circuit generates power for operating each circuit from the power line, no new power supply is required.

  The zero cross detection circuit receives light from the light emitting element that emits light when alternating current flowing through the power line is a positive voltage or a negative voltage, and receives light from the light emitting element, and outputs a zero cross point signal to the control circuit. It is desirable that it is formed by a photocoupler constituted by elements. Since the control circuit and the power line can be electrically separated by using the zero cross detection circuit as a photocoupler, the control circuit can be protected from the abnormal voltage of the power line.

  According to the transmission method of the present invention, transmission of transmitting digital signals H and L to an electric device as a communication destination through the power line in correspondence with the presence or absence of a half cycle of an alternating positive voltage or negative voltage flowing in the power line. A zero cross detection step for detecting a zero cross point at which alternating current flowing through the power line passes 0 V, and a half signal corresponding to a digital signal to be transmitted to the communication destination electrical device based on the timing of the zero cross point. AC waveform for half cycle on condition that removal instruction notifying step for instructing removal for cycle, removal instruction for half cycle, and detection of zero cross point at which AC flowing through power line passes 0V And a signal addition step of transmitting power to one or more electrical devices that are communication destinations.

  In the transmission method of the present invention, first, in a zero cross detection step, a zero cross point where the alternating current flowing through the power line passes 0V is detected. Next, in the removal instruction notifying step, removal of half a cycle is instructed in accordance with the digital signal transmitted to the communication destination electric device based on the timing of the zero cross point. Then, in the signal addition step, the AC waveform for the half cycle is removed and the communication destination and the communication destination are detected on the condition that the half cycle elimination instruction and the zero cross point where the AC flowing through the power line passes 0V are detected. The power is transmitted to one or more electrical devices. That is, the transmission method of the present invention finds the timing of the zero cross point that triggers the transmission of the digital signal, and removes the half cycle at the timing of the next zero cross point according to the digital signal to be transmitted. The delay can be slight.

  Furthermore, the dimming information transmission circuit of the lighting fixture of the present invention uses the dimming information for adjusting the luminance transmitted as H and L of the digital signal as an AC positive voltage or negative voltage half cycle flowing through the power line. A dimming information transmission circuit for a lighting fixture that transmits to a lighting fixture as a communication destination through the power line in correspondence with the presence or absence of a minute, and detects a zero cross point at which an alternating current flowing through the power line passes 0 V. A zero-cross detection circuit that outputs a signal, and a control circuit that outputs a removal signal instructing the removal of a half cycle corresponding to the digital signal transmitted to the communication destination lighting apparatus based on the reception timing of the zero-cross point signal And that the removal signal has been received and that a zero crossing point at which AC flowing through the power line passes 0V is detected. A signal adding circuit that removes an AC waveform for half a cycle and transmits power to the luminaire, and the control circuit receives the notification from the operation switch for indicating the degree of dimming as the removal signal, Dimming information including at least a transmission flag indicating the start of transmission in which the first bit is L of the digital signal, a dimming command having a predetermined number of bits indicating the degree of dimming, and an end flag indicating the end of transmission is output. It is characterized by that.

In the dimming information transmission circuit of the lighting fixture of the present invention, first, the zero cross detection circuit detects a zero cross point where the alternating current flowing through the power line passes 0 V and outputs a zero cross point signal. Next, the control circuit transmits the dimming information for adjusting the brightness by the notification from the operation switch for instructing the degree of dimming to the communication destination lighting apparatus based on the reception timing of the zero cross point signal. In response to the digital signal to be output, it is output as a removal signal for instructing removal for half a cycle. Then, on condition that the signal addition circuit has received the removal signal and that the zero crossing point at which the alternating current flowing through the power line passes 0V is detected, the alternating current waveform for half a cycle is removed to be one or more communication destinations. Power to the lighting equipment. That is, the zero cross detection circuit finds the timing of the zero cross point that triggers the transmission of the digital signal, and the signal addition circuit removes the half cycle at the timing of the next AC zero cross point according to the instruction of the control circuit. The removal delay can be small.
The dimming information includes at least a transmission flag indicating the start of transmission in which the first bit is L of the digital signal, a dimming command having a predetermined number of bits indicating the degree of dimming, and an end flag indicating the end of transmission. And can be output as a removal signal to the signal adding circuit. On the luminaire side, it can be detected that the dimming information has been transmitted by detecting the transmission flag from which the half cycle of alternating current has been removed. And a lighting fixture can perform the light control according to this light control command by receiving and analyzing the light control command of the predetermined number of bits which follows.

  According to the configuration of the present invention, the zero cross timing that triggers the transmission of the digital signal is found, and the half cycle is removed at the timing of the next zero cross point in correspondence with the digital signal transmitted to the communication destination electrical device. Therefore, the removal delay can be made small. Therefore, according to the present invention, when a signal is transmitted to a communication destination electrical device via a power line, an influence on other devices can be eliminated while reliably transmitting a digital signal. Further, when the transmitter of the present invention is a dimming information transmission circuit for a lighting fixture, the delay of removal for half a cycle of alternating current can be made small, so that the flickering of the lighting fixture can be reduced. .

It is a figure which shows the structure of the illumination system using the light control information transmission circuit which concerns on embodiment of this invention. It is a figure which shows the structure of the light control information transmission circuit shown in FIG. It is a figure for demonstrating the zero crossing detection circuit of the light control information transmission circuit shown in FIG. It is a figure for demonstrating the signal addition circuit of the light control information transmission circuit shown in FIG. And a flowchart of a program executed by the control circuit. It is a figure which shows a response | compatibility with the pressing state of each switch of an operation part, and a control command. It is a time chart explaining operation | movement of the light control information transmission circuit. It is a figure which shows the output waveform in the conventional transmission circuit.

A transmission circuit according to an embodiment of the present invention will be described with reference to the drawings, taking as an example a dimming information transmission circuit that adjusts the luminance of a lighting fixture.
As shown in FIG. 1, the dimming information transmission circuit 1 is connected to an AC power supply via a power line L, supplies power to a plurality of luminaires 2 connected in parallel, and controls dimming of the luminaire 2. Is.
The dimming control of the luminaire communicates through the power line L with dimming information transmitted as digital signals H and L corresponding to the presence or absence of a half cycle of an alternating positive voltage or negative voltage flowing through the power line L. This is done by transmitting to the previous lighting fixture 2. This light control will be described later.

As illustrated in FIG. 2, the dimming information transmission circuit 1 includes a zero cross detection circuit 10, a control circuit 20, an operation unit 30, a signal addition circuit 40, and a power supply circuit 50.
The zero cross detection circuit 10 detects a zero cross point at which 100V alternating current flowing through the power line L passes 0V and outputs it as a zero cross point signal. As shown in FIG. 3, the zero-cross detection circuit 10 includes a pair of LEDs 11a, which are light-emitting elements having opposite polarities connected when the alternating current flowing through the power line L is a positive voltage or a negative voltage, and light from the LEDs 11a. The photocoupler 11 is formed of a phototransistor 11b that is a light receiving element that is received and conducted, and a pull-up resistor 12 connected to the collector of the phototransistor 11b.

Based on the reception timing of the zero cross point signal, the control circuit 20 outputs a removal signal instructing removal for a half cycle corresponding to the digital signal transmitted to the communication destination lighting fixture 2. The control circuit 20 can be formed by a one-chip microcomputer, for example. The one-chip microcomputer uses a ROM in which a program is stored, a RAM used as a work area, an arithmetic chip, and peripheral circuits such as a clock, which are integrally formed. This is desirable because the area occupied by the substrate can be minimized.
The operation unit 30 is for performing luminance adjustment. In the present embodiment, four states can be input to the control circuit 20 by using the operation unit 30 as two switches.

  The signal addition circuit 40 removes the AC waveform for half a cycle and communicates on the condition that the removal signal from the control circuit 20 has been received and that the zero cross point where the alternating current flowing through the power line L passes 0V is detected. A function of transmitting power to the lighting fixture 2 is provided.

  As shown in FIG. 4, the signal addition circuit 40 is formed by a triac 41 and a triac driver circuit 42. The triac 41 applies the ON signal to the gate terminal G to make the terminal A1 and the terminal A2 conductive, and applies the OFF signal to the gate terminal G to make the terminal A1 and the terminal A2 nonconductive. It is a bidirectional thyristor to be in a state. The triac driver circuit 42 detects a zero cross point when the removal signal output from the control circuit 20 becomes valid (“L”), and is a half cycle period from the detected zero cross point to the next zero cross point, The gate terminal G of the triac 41 is provided with a function of outputting a gate control signal for turning off. When detecting the zero cross point when the removal signal is valid, the triac driver circuit 42 is in a non-conductive state until the next zero cross point is detected even if the removal signal becomes invalid (“H”). Maintain the gate control signal.

  The power supply circuit 50 supplies a DC voltage necessary for each of the zero-cross detection circuit 10 and the control circuit 20 from the AC from the power line L. In the power supply circuit 50 of the present embodiment, a direct current of about 3 V is generated from the alternating current of 100 V of the power line L and output.

As shown in FIG. 1, the lighting fixture 2 includes an AC-DC conversion circuit 60, a receiving circuit 70, a dimming circuit 80, and LED lighting 90.
The AC-DC conversion circuit 60 is a converter that converts the alternating current 100V from the dimming information transmission circuit 1 into a direct current of about 70V.
The receiving circuit 70 checks the presence / absence of a half cycle of alternating current from the dimming information transmission circuit 1, extracts a digital signal corresponding to the presence / absence as dimming information, and controls the dimming from a control command included in the dimming information A function of outputting luminance information instructing luminance dimming to the circuit 80 is provided.
The dimming circuit 80 performs a PWM (Pulse Width Modulation) control to increase or decrease the pulse width of the power supplied to the LED lighting 90 based on the luminance information from the receiving circuit 70, and adjusts the luminance of the LED lighting 90. It has.

The operation and use state of the dimming information transmission circuit 1 configured as described above will be described with reference to the drawings.
First, as shown in the flowchart of FIG. 5, the control circuit 20 monitors whether or not the operation unit 30 is operated when power is supplied (step S10).
When it is recognized that the control circuit 20 has been operated, the operation content is analyzed (step S20). And the control circuit 20 produces | generates the light control information containing the control command transmitted to the lighting fixture 2 of a communication destination according to operation content (step S30).

When the operation unit 30 is, for example, two switches A and B, as shown in the table of FIG. 6, when both the switches A and B are not pressed, it is in a normal use state. Therefore, the control circuit 20 does not issue a control command.
When only the switch A is pressed, control commands “L” and “H” are generated to indicate that the luminance is reduced.
When only the switch B is pressed, control commands “H” and “L” are generated to indicate that the brightness is increased.
When both switches A and B are pressed, control commands “L” and “L” are generated as indicating the maximum luminance.
The control circuit 20 adds a transmission flag and an end flag to this control command, and outputs it as dimming information.

  Here, the timing at which the control circuit 20 outputs dimming information and the timing at which the dimming information from the control circuit 20 is transmitted to the lighting fixture 2 together with the supply of power will be described in detail with reference to the drawings.

  First, an operation in which the zero-cross detection circuit 10 detects an alternating zero-cross flowing in the power line L will be described. As shown in FIG. 3, when the alternating current of the power line L flows through the pair of LEDs 11a, when the alternating current is a positive voltage or a negative voltage, one of the LEDs 11a is in a lighting state, and when passing through 0V, both are turned off. It becomes a state.

  When the LED 11a is turned on, a current flows through the phototransistor 11b and no signal is output. However, when the LED 11a is not turned on, no current flows through the phototransistor 11b, so that the output from the photocoupler 11 is output by the pull-up resistor 12. It becomes a pulse signal.

  As shown in FIG. 7, this pulse signal is output to the control circuit 20 as a zero cross point signal S1 indicating the zero cross point at which the alternating current is 0V. That is, the zero cross point signal S1 is output from the zero cross detection circuit 10 when it becomes 0 V when transitioning from an alternating negative voltage to a positive voltage and from a positive voltage to a negative voltage. Note that the zero cross detection circuit 10 does not output the zero cross point signal S1 only when the alternating current is 0 V, but by adjusting the current flowing from the power line L to the LED 11a, the signal output as the zero cross point signal S1 is predetermined. The pulse width can be set.

  The control circuit 20 does nothing when the operation unit 30 is not operated, but when the operation unit 30 is operated, dimming including a control command corresponding to the operation of the operation unit 30 is performed in step S20 shown in FIG. Generate information.

Then, the control circuit 20 sequentially outputs dimming information to the signal adding circuit 40 from the transmission flag that is the first bit as a removal signal that is a digital signal that becomes serial data based on the reception timing of the zero cross point signal S1. At this time, if each bit of the removal signal is a digital signal “L” (negative logic), the control circuit 20 delays by a predetermined time from the zero cross point P1 indicated by the zero cross point signal S1 and outputs it with a predetermined width (FIG. 7 (see the delay time D of the removal signal S2 shown in FIG. 7).
The delay time D of the removal signal S2 is set to be less than a half cycle so that the signal addition circuit 40 can add a digital signal to the alternating current from the next zero cross point P2. Further, the signal width of the removal signal S2 is set so that the sum of the delay time and the delay time is less than one cycle in order to include the next zero cross point P2 and not include the next zero cross point P3. .

In the control circuit 20 of the present embodiment, if the alternating current is 60 Hz, the half cycle is about 8.3 mS. Therefore, by delaying each bit of the removal signal S2 by about 4 mS from the pulse position of the zero cross point signal S1, The margin to the next zero cross point P2 is secured about 4.3 mS. Further, by outputting the signal width at about 10 mS, the next zero cross point P2 can be included, and the next zero cross point P3 of the included zero cross point P2 can be removed.
In this manner, the control circuit 20 outputs the dimming information including the transmission flag, the control command, and the end flag to the signal addition circuit 40 as the removal signal S2 as described above.

  When the removal signal from the control circuit 20 is “H”, that is, when the operation unit 30 is not operated, any bit of the dimming information is set to “H” when the operation unit 30 is operated. In some cases, the triac driver circuit 42 of the signal addition circuit 40 shown in FIG. 4 outputs the gate control signal S3 that makes the triac 41 conductive, to the gate terminal G. Therefore, the alternating current from the power supply side is output to the lighting fixture 2 as it is. By doing so, since the triac 41 is in a conductive state, the positive voltage and the negative voltage of the power line L are not lost, and the AC waveform is supplied as it is to the lighting fixture 2.

When the signal (dimming information) from the control circuit 20 is “L”, the triac driver circuit 42 from the zero cross point when the removal signal becomes valid (“L”) to the next zero cross point. During the period, the gate control signal S3 for turning off the gate terminal G of the triac 41 is output for about a half cycle. By doing so, since the triac 41 is in a non-conducting state, the AC waveform S4 lacking a half cycle of the negative voltage is transmitted to the lighting fixture 2.
In the example illustrated in FIG. 7, only the switch A of the operation unit 30 is pressed and the switch B is not pressed, so that the control commands “L” and “H” are transmitted as dimming information together with the transmission flag and the end flag. The state output from the control circuit 20 is shown.

In the lighting fixture 2, when the receiving circuit 70 receives the alternating current from which the half cycle has been removed, the receiving circuit 70 recognizes that it is a transmission flag indicating the start of transmission of dimming information. Then, the receiving circuit 70 recognizes the two bits transmitted following the transmission flag as a control command and the last one bit as an end flag, and outputs luminance information corresponding to the control command to the dimming circuit 80.
In the light control circuit 80, the brightness | luminance of the LED illumination 90 is changed by increasing / decreasing the pulse width of the power supply supplied to the LED illumination 90 according to brightness | luminance information.

  In this way, the zero cross detection circuit 10 finds the timing of the zero cross point that triggers the transmission of the digital signal, and the signal addition circuit 40 follows the instruction of the half cycle removal output from the control circuit at the timing of the next zero cross point. Since half a cycle is removed, the removal delay can be made small.

  Therefore, when the dimming information transmission circuit 1 according to the present embodiment transmits a signal to the lighting fixture of the communication destination via the power line L, the digital light signal is reliably transmitted and the influence on other devices is affected. Don't give. Moreover, the dimming information transmission circuit 1 can reduce the flicker of the lighting fixture 2.

  In this embodiment, since the control circuit 20 delays and outputs the removal signal, the zero cross point P1 recognized by the control circuit 20 is mistaken as the zero cross point P2 at which the signal addition circuit 40 starts adding the digital signal. Can be prevented. Further, by setting the signal width of the removal signal to a time width including the zero cross point P2 next to the zero cross point P1 that the control circuit 20 uses as a trigger for transmission of the removal signal S2, the signal addition circuit 40 can reliably ensure the next zero cross. A half cycle is removed from the point P2, and a digital signal can be added to the alternating current.

Further, since the power to the pull-up resistor 12 of the zero-crossing detection circuit 10 and the control circuit 20 is supplied from the power supply circuit 50 generated from alternating current, it is not necessary to provide a power supply line separately from the power line L.
Further, the zero-cross detection circuit 10 is formed by the photocoupler 11 including the LED 11a that emits light when the alternating current flowing through the power line L is a positive voltage or a negative voltage, and the phototransistor 11b. 20 is not applied. Therefore, the control circuit 20 can be protected.

  In this embodiment, as the dimming information, a 1-bit transmission flag, a 2-bit control command, and a 1-bit end flag are used. However, if the first 1 bit of the transmission flag is a digital signal “L”, A multi-bit predetermined pattern may be used, and the end flag may be a multi-bit predetermined pattern. Also, the control command may be 1 bit or 3 bits or more depending on the type of control. Furthermore, it is possible to add an address of 1 bit or more for identifying the electric appliance of the communication destination, and to add an error detection code and an error correction code. Moreover, although what removed the half cycle of alternating negative voltage is transmitted to the lighting fixture 2, it is good also as what removed the half cycle of positive voltage.

  In the present embodiment, the operation unit 30 has two switches A and B. However, the number of switches can be increased or a rotary switch can be used according to the type of control command. Furthermore, if a remote control transmitter using an infrared ray or a radio signal is combined with a receiver and a signal received by the receiver is input to the control circuit, one or more electric devices can be remotely controlled.

  The transmission circuit of the present invention is suitable not only for lighting fixtures but also for remote control of electrical equipment using an AC power supply, and particularly for lighting fixtures, a dimming information transmission circuit is provided in the wall together with a lighting switch. Therefore, the brightness can be easily adjusted, which is optimal.

DESCRIPTION OF SYMBOLS 1 Dimming information transmission circuit 10 Zero cross detection circuit 11 Photocoupler 11a LED
11b Phototransistor 12 Pull-up resistor 20 Control circuit 30 Operation unit 40 Signal addition circuit 41 Triac 42 Triac driver circuit 50 Power supply circuit 2 Lighting fixture 60 AC-DC conversion circuit 70 Reception circuit 80 Dimming circuit 90 LED illumination S1 Zero cross point signal S2 Removal signal S3 Gate control signal S4 AC waveform P1 to P3 Zero cross point L Power line

Claims (5)

A transmission circuit that transmits digital signals H and L to an electrical device that is a communication destination through the power line in correspondence with the presence or absence of a half cycle of an AC positive voltage or negative voltage flowing in the power line,
A zero-crossing detection circuit that detects a zero-crossing point at which alternating current flowing through the power line passes 0 V and outputs a zero-crossing point signal;
Based on the reception timing of the zero cross point signal, a control circuit that outputs a removal signal instructing removal of half a cycle corresponding to a digital signal transmitted to the communication destination electrical device;
On the condition that the removal signal is received and a zero crossing point at which the alternating current flowing through the power line passes 0V is detected, the alternating current waveform for half a cycle is removed and the power is transmitted to one or more electrical devices that are communication destinations. and a signal adding circuit,
The control circuit delays the output start of the removal signal from the received zero cross point signal, and sets the signal width of the removal signal to a time width including a zero cross point next to the zero cross point. .   The transmission circuit according to claim 1, further comprising: a power supply circuit that generates a power supply necessary for each circuit from an alternating current flowing through the power line. The zero cross detection circuit receives light from the light emitting element that emits light when alternating current flowing through the power line is a positive voltage or a negative voltage, and receives light from the light emitting element, and outputs a zero cross point signal to the control circuit. transmission circuit according to claim 1 Symbol mounting is formed by a photocoupler constituted by the elements. A transmission method for transmitting digital signals H and L to an electrical device as a communication destination through the power line in correspondence with the presence or absence of a half cycle of an AC positive voltage or negative voltage flowing in the power line,
A zero cross detection step of detecting a zero cross point where the alternating current flowing through the power line passes 0V;
Based on the timing of the zero cross point, when instructing the removal of a half cycle corresponding to the digital signal transmitted to the electrical device of the communication destination, the half cycle is delayed from the timing of the zero cross point. A removal instruction notifying step in which a width to be removed is a time width including a zero cross point next to the zero cross point ;
On the condition that the half cycle removal instruction and the detection of a zero cross point where the alternating current flowing through the power line passes 0V, one or more electrical devices that remove the half cycle alternating waveform and become a communication destination And a signal adding step for transmitting power to the transmission method. The dimming information for adjusting the luminance transmitted as H and L of the digital signal corresponds to the presence or absence of half cycle of AC positive voltage or negative voltage flowing through the power line, and becomes a communication destination through the power line A dimming information transmission circuit for a luminaire to transmit to the luminaire,
A zero-crossing detection circuit that detects a zero-crossing point at which alternating current flowing through the power line passes 0 V and outputs a zero-crossing point signal;
Based on the reception timing of the zero cross point signal, a control circuit that outputs a removal signal instructing removal of a half cycle corresponding to a digital signal transmitted to the communication destination lighting fixture;
On the condition that the removal signal is received and a zero cross point at which the alternating current flowing through the power line passes 0 V is detected, the alternating current waveform for half a cycle is removed, and one or more lighting fixtures serving as communication destinations A signal addition circuit for transmitting power,
The control circuit delays the output start of the removal signal from the received zero cross point signal , sets the signal width of the removal signal to a time width including the next zero cross point of the zero cross point, and indicates the degree of dimming As a result of the notification from the operation switch, a transmission flag indicating the start of transmission in which the first bit becomes L of the digital signal, a dimming command having a predetermined number of bits indicating the degree of dimming, and the transmission end as the removal signal A dimming information transmitting circuit that outputs dimming information including at least an end flag indicating

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