JPS5919429B2 - dimmer circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dimming circuit that can be used in a remote control system that transmits digital information.

Figure 1 shows an example of a conventional dimming circuit using phase control.
The switching element D2 detects the terminal voltage of the capacitor Cl and triggers the phase control element 4, such as a bidirectional three-terminal thyristor.Dimming is performed by controlling the phase of the current flowing from the power source AC to the lighting load 3. .

FIG. 2 is a time chart of the circuit in FIG. 1, in which a shows the relationship between the power supply waveform shown in a) and the voltage waveform of the capacitor Cl shown in FIG.
In addition, b in the same figure shows the plague over voltage of
indicates the gate input of the phase control element 4, and c indicates the load current flowing to the lighting load 3, respectively. In the circuit shown in Figure 1, R1 is a variable resistor for dimming, R2 is a dummy resistor, and these resistors R4
, R2 and a capacitor Cl constitute a phase shift circuit. However, in the conventional dimming circuit shown in FIG. 1, by appropriately setting the dimming variable resistor R3, the timing at which the terminal voltage of the capacitor Cl exceeds the breakover voltage VL of the switching element D2 can be determined. Therefore, the phase angle of the power supply AC that the phase control element 4 conducts can be freely adjusted.
However, in order to perform this type of dimming control, it is necessary to control the dimming level by operating the dimming variable resistor while visually checking the lighting status of the lighting load. Therefore, there was a problem in that it was difficult to control the dimming level from a remote location without visual inspection. The present invention has been provided in view of the above-mentioned points, and allows dimming control from a remote location by using data transmission of digital information by performing dimming by inputting digital setting values. In addition, in particular, the phase control operation should be performed with a certain time delay from the detection of the zero crossing point! A dimming control system that brings the correspondence between the dimming control level set by 1 and the brightness level that is actually felt with the naked eye, and allows accurate dimming control to be performed with a smaller number of setting levels. The purpose is to provide a circuit.

1 Below, one embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 3 shows an example of the basic configuration of a remote control system to which the dimmer circuit A of the present invention is applied. A large number of terminal devices 11 are connected to a central control device 10 by transmission lines 12. Central control device 1
0 sends out an address signal for individually calling each terminal 11 and a control signal (formed as a several-bit digital signal) for the called terminal 11. When the terminal device 11 determines that the received address signal matches its own address, the terminal device 11
After detecting the call from the central control device 10 and latching the control signal following this address signal, the required load connected to this terminal device 11 is controlled based on this latch information. When this terminal device 11 is for dimming a lighting load 32 having a dimming circuit A, the latch information is the digital setting information for the dimming circuit A, and the latch circuit itself that latches the control signal is This constitutes a digital setting device 6 for setting digital setting values. In each of the following embodiments, the control signal is composed of a 4-bit binary code, and therefore the digital setting device 6 is also composed of a 4-bit latch circuit. Fig. 4 shows one embodiment of the present invention. An example circuit diagram is shown.

In the circuit shown in FIG. 4, comparators 7 A, B, C, 3!
The D input terminals are connected to the latch output terminals A, B, C, and D of the digital setting device 6 on the terminal device 11 side, respectively, and the 123 terminal of the dimming control section 13 is connected to the dimming ballast 14. 12 of
Connected to 3 terminals. Therefore, in the embodiment circuit of FIG. 4, the transformer T steps down the voltage shown in FIG. At the same time, diode bridge DB
This full-wave rectified output is used as a power supply for circuit operation, and this full-wave rectified output is input to the base of the transistor Tr. A zero-cross detection circuit 8 is constructed, and this zero-cross detection circuit 8 generates an output signal at the timing when the power supply voltage waveform crosses zero volts, as shown in FIG. 5b. Reference numeral 1 designates a pulse oscillation circuit, which starts oscillation operation at a timing delayed by a delay circuit 9 for a predetermined time after the output of the rising zero cross detection circuit 8 falls and the signal via the inverter INV becomes high level. Next, the oscillation operation is continued until an output signal is generated in the zero cross detection circuit 8, and this is repeated for each half cycle of the power supply AC.

5 is a counter, which is shown in FIG. 5c of the pulse oscillation circuit 1.
The output pulse count is configured to be reset by the output signal of the zero-cross detection circuit 8. Therefore, each time an output pulse is generated in the zero-cross detection circuit 8, the falling edge of this output pulse is set. The counter 5 is reset at this timing, and the counter 5 counts the output pulses of the pulse oscillation circuit 1, which starts oscillating after a predetermined delay time by the delay circuit 9 has elapsed from this timing.
The binary output of this counter 5 is input to one input terminal of a comparator 7.

In this way, the comparator 7 generates an output signal as shown in FIG. The output turns on the transistor Tr2 and obtains the collector output as shown in Figure 5e.
The light emitting diode LED is turned on at the timing when the transistor Tr2 is turned on. Here, the capacitor C2 widens the pulse width of the light emitting diode LED current by allowing current to flow through the light emitting diode LED at the initial stage of turn-off even when the transistor Tr2 is off. Thus, the light from the light emitting diode LED enters the phototransistor PTR, and the output of the phototransistor PTR turns off the transistor Tr3 and turns on the reverse blocking three-terminal thyristor S1. When the reverse blocking three-terminal thyristor S1 is turned on, a gate signal is supplied to the phase control element 4, which is a bidirectional three-terminal thyristor, via the diode bridge DBl, and the comparator 7
The phase control element 4 is triggered to conduct at the timing when the output is generated, and the lighting load 3 is dimmed and lit via the dimming ballast 14. Figure 5f shows the waveform of the current of the phase control element 4. It shows. However, in the embodiment circuit of FIG. 4, a resistor R is provided on the output side of the inverter INV. , a capacitor C3, and a diode D are inserted to obtain a delay time indicated by TD in FIG. 1 starts the oscillation operation and performs the phase control operation. The reason why the zero cross detection signal is delayed by the delay time TD by the delay circuit 9 is that each dimming level set in the digital setting device 6 corresponds to the brightness perceived by the naked eye when the lighting load 3 is actually dimmed. This is to improve relationships. That is, if one half cycle of one power supply AC is divided into 16 equal parts by the output pulse of the pulse oscillation circuit 1,
The illuminance ratio changes as shown in FIG. 6 when the light is dimmed at each of the dimming levels 0 to 5, but the illuminance ratio hardly changes at the dimming levels 0 to 5. Therefore, in the present invention, the oscillation operation of the pulse oscillation circuit 1 is stopped during the period when the change in the illuminance ratio is small, and then the output pulse of the pulse oscillation circuit 1 is used to equally divide the remaining period b of the power supply half cycle. This allows the setting of the light level. Thus, in the present invention, the correspondence between the digitally set dimming level and the actual dimmed illuminance ratio is improved, and the precision of dimming with respect to the number of levels is improved. When the output of the digital setting device 6 is level 15, the transistor Tr4 in the circuit in Figure 4 is
This is to prevent the phase control element 4 from erroneously firing due to the light emission pulse width of the light emitting diode LED extending to the period of level O. Further, in the circuit shown in FIG. 4, a trigger control circuit 2 is constituted by a pulse oscillation circuit 1, a counter 5, a comparator 7, a zero cross detection circuit 8, a light emitting diode LED, etc., and a phototransistor PTR1, a reverse blocking 3-terminal thyristor S1, a diode Bridge DB,
The output of the trigger control circuit 2 and the input of the dimming control section 13 are composed of a light emitting diode LED and a phototransistor PTR.
Both are optically coupled. In addition, the time chart in Figure 5 shows that the A, B, C, and D inputs of comparator 7 are each 0.
, 1, 1, 0. FIG. 7 is a circuit diagram of another embodiment of the present invention.

In this embodiment circuit of FIG. 7, T of the phase control element 4 is
Including the 2-G terminal, a diode bridge DBl, a light emitting diode LED, a phototransistor PTR, and a zero cross detection circuit 8' for detecting the zero cross point of the high load current are formed.1This zero cross detection circuit 8
The output signal of ' is inputted to the counter 5 and the delay circuit 9 at the front stage of the pulse oscillation circuit 1 via the inverter INV in the same manner as the output signal of the zero cross detection circuit 8 of the embodiment shown in FIG. The phase control element 4 is ignited by the same operation as in the illustrated embodiment. Fig. 8 is a time chart of the circuit shown in Fig. 7, where a is the voltage waveform of the power supply AC, b is the voltage waveform of the phase control element 4, and c is the phototransistor PT.
d is the output voltage waveform of the pulse oscillation circuit 1, e is the output voltage waveform of the converter 7, f is the collector voltage waveform of the transistor Tr2, and g is the current waveform of the phase control element 4. In the case of this FIG. 7 embodiment, the fourth
As in the case of the illustrated embodiment, the correspondence relationship between the digitally set dimming level and the illuminance ratio of the dimmed lighting load matches well, and the accuracy of dimming control is also improved. In each of the embodiments shown in FIG. 4 and FIG. A control circuit may be configured, and
A subtraction counter is preset based on the control data received by the terminal device 11, and the preset value of the subtraction counter is sequentially subtracted by the pulse oscillation circuit output, and when the content of the subtraction counter becomes zero, the phase control element 4 is triggered. It's fine to do it this way.

Furthermore, in each of the embodiments described above, the output (of the comparator) is generated only when the digital setting value and the counter count value match, but when the counter count value exceeds the digital setting value, the output signal is generated. It goes without saying that the output signal may be continuously generated when the L counter count value>digital set value. Since the present invention is configured as described above, the dimming level can be set remotely by using a remote control system that digitally transmits information, and the lighting load can be controlled remotely. In particular, in the present invention, the oscillation burst of the pulse oscillation circuit is started by the output obtained by delaying the zero cross detection output with a delay circuit. This has the effect of improving the correspondence between the digitally set dimming level and the actually obtained illuminance ratio, and enabling accurate dimming control even with a small number of dimming levels.

Brief explanation of the drawings Fig. 1 is a circuit diagram of a conventional dimmer circuit, Fig. 2 is a time chart of the same as above, and Fig. 3 is a basic configuration diagram of a remote control system that uses the dimmer circuit of the present invention. Figure 4 is a circuit diagram of one embodiment of the present invention, Figure 5 is a time chart of the same as above, Figure 6 is a characteristic diagram of the relationship between dimming level and illuminance ratio, and Figure 7 is a diagram of another embodiment of the present invention. The circuit diagram and Figure 8 are the same time charts as above.
is a pulse oscillation circuit, 2 is a trigger control circuit, 3 is a lighting load, 4 is a phase control element, 5 is a counter, 6 is a digital setting device, 7 is a comparator, 8 and 8' are a zero cross detection circuit, and 9 is a delay circuit. be.

Claims (1)

[Claims] 1. A zero-crossing detection circuit that detects a zero-crossing point of a voltage signal obtained from the same power source as the lighting load to be dimmed or a load current flowing through the lighting load, and a zero-crossing detection circuit that delays the output of this zero-crossing detection circuit for a certain period of time. and a pulse oscillation circuit that starts oscillation operation by the output of this delay circuit, counts the oscillation output of this pulse oscillation circuit, and outputs a pulse when the counted value matches a remotely set digital setting value. 1. A dimmer circuit comprising: a trigger control circuit that generates a signal, and an output of the trigger control circuit triggers a phase control element of a lighting load. 2. A counter that counts the oscillation output of the pulse oscillation circuit;
The trigger control circuit is comprised of a digital setting device that can be freely set by remote control, and a comparator that compares the outputs of both the counter and the digital setting device and generates an output pulse when they match. A light control circuit according to claim 1. 3 Configure a trigger control circuit with a presettable subtraction counter, preset a desired digital setting value by remote control, subtract and count the output of the pulse oscillation circuit, and trigger the phase control element with the O output of this subtraction counter. A light control circuit according to claim 1, characterized in that the light control circuit comprises: