JP2675201B2 - Light control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for continuously changing the dimming level of a lighting load, and more particularly to a low-priced, small dimming device for household use.

[0002]

2. Description of the Related Art FIG. 7 shows an electrical structure of a conventional light control device. Electric power from the AC power supply 1 is given to a lighting load 2 such as a lighting lamp. The phase of this electric power is controlled by a switching element 3 such as a bidirectional three-terminal thyristor that forms a closed loop with the AC power supply 1 and the lighting load 2.
The dimming level to be phase-controlled so that the lighting load 2 has a desired brightness is given by the input means 4. The control means 5 responds to the output from the zero-cross point detecting means 6 that detects the zero-cross point of the output voltage of the AC power supply 1, and switches the switching element at a trigger timing according to the dimming level for each half cycle of the AC power supply 1. Repeat 3 trigger control. Since the phase control is performed by digital control, the clock signal generated from the reference clock circuit 7 is counted by the counting means 8. The count value corresponding to the dimming level is set in the counting means 8 by the control means 5. When this count value is reached, the switching element 3 is driven through the trigger driving means 9.
Is driven.

FIG. 8 is a waveform diagram for explaining the operation of the configuration shown in FIG. FIG. 8 (1) shows a state in which the switching element 3 is phase-controlled with respect to a change in the output voltage of the AC power supply 1. The phase of the switching element 3 is controlled so that the switching element 3 conducts only for each half cycle ½ W, which is a half cycle of one cycle W of the AC power supply 1.

FIG. 8 (2) shows zero-cross points t10 and t2.
The relationship between 0, t30 and the trigger timings T1s, T2s is shown. FIG. 8C shows the reference clock signal, and indicates that the time point when N1 pieces have been counted from the zero-cross point t10 is the trigger timing T1s. In the fade control or the like, the trigger timing T is set every half cycle of the AC power supply 1.
The brightness of the lighting load 2 is continuously changed by continuously changing 1s and T2s.

In the conventional dimming device, in order to finely set the dimming level, it is necessary to finely generate the reference clock signal for each half cycle of the AC power supply 1. For example, the frequency of the AC power supply 1 is 50 Hz
For a half cycle period of 10 ms and 8.3 ms at / 60 Hz, a reference clock signal with a period of several tens of microseconds is required.

In the conventional light control device shown in FIG. 7, in order to count such a reference clock signal, a counting means and a control unit having a large number of bits, for example 8 bits or more, are required. This is because if the frequency of the AC power supply 1 is 50 Hz with a reference clock signal of 50 μs, 200
This is because it is necessary to count the count.

If a large number of dimming levels are not required, it is conceivable to set the period of the reference clock signal larger, but when the dimming level is changed, it is possible for humans to change the brightness. Is identified as being gradual.

Therefore, in the conventional dimming device, in order to smoothly change the dimming level, 8 bits or more are used as the counting means and the control means for performing the operation for setting the count value. Therefore, it is difficult to manufacture the dimmer in a small size and at a low cost.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a small and inexpensive light control device which can smoothly change the brightness of a lighting load.

[0010]

According to the present invention, a closed loop is formed by a lighting load, an AC power supply and a switching element,
In a dimming device that controls the phase of a lighting load by a switching operation of a switching element to continuously change the dimming level of the lighting load, an input unit that provides a continuously changing dimming level and an alternating current that drives the lighting load. Since each half cycle of the output from the power supply is divided into multiple sections where the change in the dimming level due to phase control is difficult for humans to distinguish between consecutive divided sections, a pulse signal is generated for each divided section. The generating means, the counter for counting the pulse signals from the pulse generating means with a predetermined number of bits smaller than the number of bits required for expressing the plurality in binary numbers, and each half cycle of the output from the AC power supply. , Within each phase angle section, the counter divides the pulse signal into a plurality of phase angle sections capable of counting, and for each half cycle, a dimming level given from the input means. It is determined which one of the plurality of phase angle sections the corresponding controllable phase angle belongs to, and the counter corresponding to the phase angle is counted by the counter in the determined phase angle section to set the lighting load to the phase. It is a dimmer which is characterized by including control means for controlling.

[0011]

According to the invention, a continuously changing dimming level for dimming the lighting load is provided by the input means. The control means controls the phase of the switching element with a phase angle corresponding to the dimming level, and controls the electric power supplied from the AC power supply to the lighting load. The control means determines to which of the phase angle sections each half cycle of the output from the AC power supply is divided into a plurality, the phase angle for which the phase of the switching element should be controlled, and within the determined phase angle section. , The pulse signal from the pulse generating means is counted by the counter so that the count value corresponds to the phase angle. This pulse signal is generated for each section in which each half cycle of the output from the AC power supply is divided into continuous division sections to the extent that a change in the dimming level due to phase control is difficult for humans to identify. Since the number of bits of the counter may be smaller than the number of bits required to express a plurality of divisions of each half cycle of the output of the AC power supply in binary number, the number of bits of the control means for setting the count value in the counter or the like. The number can also be reduced, and the device can be made compact and at low cost. Therefore, the brightness of the illumination load can be smoothly changed, and a small and inexpensive dimmer can be obtained.

[0012]

FIG. 1 is a block diagram showing an electrical configuration of an embodiment of the present invention. The AC power supply 11, the illumination load 12 such as an illumination lamp, and the switching element 13 such as a bidirectional three-terminal thyristor form a closed loop. The electric power for energizing the lighting load 12 from the AC power supply 11 is phase-controlled by the switching element 13. Lighting load 12
Brightness continuously changes according to the dimming level provided by the input means 14. Such phase control is
It is controlled by the control means 15 having a small number of bits. The minority bit control means 15 includes, for example, a microcomputer or a memory that processes a 4-bit signal in parallel. The output from the zero-cross detection means 16 is given to the control means 15 for a small number of bits. Zero cross detection means 1
Reference numeral 6 detects a zero-cross point at which the output voltage of the AC power supply 11 becomes zero every half cycle, and derives a signal indicating the detection. The phase control for smoothly changing the brightness of the illumination load 12 is performed by counting the clock signal from the basic clock circuit 17 by the counting unit 18 of a small number of bits. The cycle of the clock signal is set to about several tens of microseconds so that it is difficult for humans to identify the change in the brightness of the illumination load 12 even if the phase is controlled between the cycles. The minority bit counting means 18 is composed of a counter having the same number of bits as the minority bit control means 15, for example, a 4-bit counter. The output from the minority bit counting means 18 drives the control input terminal of the switching element 13 via the trigger driving means 19.

FIG. 2 is a waveform diagram for explaining the state of phase control of the switching element 13 according to the embodiment shown in FIG. FIG. 2 (1) shows, for the output voltage waveform of the AC power supply 11, the section of the phase angle in which the switching element 13 is conducted, with hatching. FIG. 2 (2) shows the time associated with the basic clock signal and the phase control. The phase number corresponding to the dimming level given by the input means 14 is the phase obtained by dividing the half cycle of the output voltage waveform of the AC power supply 11 into four in FIG. Which of the sections it belongs to is determined.
Each phase section is set to be a section when the decimal bit counting means 18 counts the maximum number of basic clock signals. The minority bit control means 15 causes the minority bit counting means 18 to count the basic clock signal from the zero-cross point t10, and recognizes the progress of the phase sections 1 and 2 each time the minority bit counting means 18 overflows. . In the phase section 3 to which the phase angle to be phase controlled belongs, the minority bit control means 15 sets the count value n1 corresponding to the phase angle in the minority bit count means 18. When the counting means 18 for a small number of bits counts n1 basic clock signals from the time t1n, the time t1 corresponding to the phase angle is obtained.
s. The switching element 13 is cut off from the time t10 to this time t1s, and the switching element 13 is made conductive until the next zero cross point t20. Zero cross point t2
Even during the half cycle of the AC power source from 0 to the next zero cross point t30, the time t2s is set by the value of the phase angle corresponding to the dimming level, and the switching element 13 is cut off in the section from the zero cross point t20 to t2s. In this state, the phase is controlled so that the switching element 13 becomes conductive in the section from t2s to the next zero cross point t30. The dimming level can be changed by changing the timing of times t1s and t2s with reference to the zero-cross points t10 and t20.

In FIG. 3, each half cycle of the AC power supply 11 is divided into three phase sections, and the count value corresponding to the phase angle at which the switching element 13 starts conducting is from C11 to C.
A state in which fade control is performed so as to change up to 31 is shown. Count value C1 corresponding to the phase angle at the start of fade control
1 belongs to the first phase section C1. The count value C31 corresponding to the phase angle at the end of the fade control belongs to the third phase section C3. The fade control time is t1 for the first phase control section C1, t2 for the second phase section C2, and t3 for the third phase section C3.

FIG. 4 shows the configuration of FIG. 3 according to the embodiment shown in FIG.
9 is a flowchart illustrating an operation for performing fade control as illustrated. At step a1, the output from the zero-cross detection means 16 causes the minority bit control means 15 to start interrupt processing. Next step a2
At, it is determined whether or not the fade control process is being performed. If the fade control process is in progress, step a3
Move on to

When the fade control time is tt, the fade control time t1, t2, tn-1,
tn is in the relationship of the following expression 1.

[0017]

## EQU1 ## t1 + t2 + ... + tn-1 + tn = tt In the first phase section, the count value C represented by the following expression 2 is set in the decimal bit counting means 18.

[0018]

(Equation 2)

The count value C when the phase angle belongs to each of the 2nd, ..., N-1th, and nth phase sections is obtained by the following equations 3, 4, and 5.

[0020]

(Equation 3)

[0021]

(Equation 4)

[0022]

(Equation 5)

Here, C1, C2, ..., Cn-1 is 1
The count value corresponding to the entire 1st, 2nd, ..., N-1th phase section, Cn1 is the final count value in the nth phase section.

At step a3, the count value C is obtained corresponding to the elapsed time t from the start of the fade control. At step a4, the count value C overflows the counting means 18 having a small number of bits by the number of bits. It is determined whether or not to do it. When there is an overflow of the number of bits, in step a5, the counting means 18 for the small number of bits is used.
The phase angle section to which the phase angle to be phase-controlled belongs is determined by the number of overflows.

When there is no overflow of the number of bits in step a4 or when the processing in step a5 is completed, the reference clock signal is counted in step a6. When it is determined by the counting process of the reference clock signal that the time corresponds to the phase angle to be phase-controlled, in step a7, it is determined whether the count of the final dimming level of the fade control and the phase angle section to which the phase angle belongs have been reached. Is determined. When the final light control level is reached, the flag indicating the completion of fade is set in step a8. When the flag indicating the completion of the fade is set, it is determined in step a2 that the fade control process is not in progress. In step a7, when it is determined that the fade control is not in the final section, when step a8 is finished, and when it is determined that the fade control process is not in progress in step a2, the process proceeds to step a9, and the phase control for each section is performed. After that, the process ends in step a10.

FIG. 5 is a flow chart for explaining the operation of the counting process. At step c1, the counting process is started. In step c2, it is determined whether or not the phase angle belongs to a section exceeding the section 1.
If the interval exceeds 1, in step c3, the count value of the minority bit counting means 18 is set to zero.
That is, C1, C2, ..., Cn-1 are 16 which is the maximum value of a 4-bit binary number. Next, in step c4, the reference clock signal from the reference clock circuit 17 is counted, the count value of the counter is decremented by decrementing by one. Since zero is initially set as the count value, all the bits of the counter change from 0 to 1 when decremented for the first time. Next, at step c5, it is judged if the count value becomes zero again.
Steps c4 and c5 are repeated until the count value becomes zero. Next, in step c6, the number of sections is decreased by 1, the sections are decremented, and the process returns to step c2. In this way, the section is decremented until the phase section to which the phase angle belongs is reached.

When it is determined in step c2 that the value of the section does not exceed 1, the process proceeds to step c7. At this time, since the phase angle for starting the phase control belongs to this phase section, the count value C obtained in step a3 is set. Next, step c8 and step c9
At step c10, the counter is decremented by the basic clock signal, and when the count value becomes zero, the process is terminated at step c10. In this way, by using the counting means 18 of a small number of bits, it is possible to give a smooth change of the phase angle, as in the case of using the counting means of a larger number of bits.

FIG. 6 is a flow chart for explaining the operation of fade control according to another embodiment of the present invention.
The operation for fade control is started in step b1 by a zero cross interrupt, as in the embodiment shown in FIG. In step b2, it is determined whether or not the fade control is being performed by a flag indicating whether or not the fade control is being performed. When the fade control is being performed, in step b3, the count number for counting the clock signal is obtained by the following equation 6.

[0029]

[Equation 6] C + ΔC = C Here, C is a count value to be set in the counting means 18 of a small number of bits. ΔC is a value whose count value should be changed for each half cycle, and is given by the following equation 7.

[0030]

(Equation 7)

Here, C1, C2, ..., Cn-1 represent respective count numbers corresponding to the entire first, second and n-1th phase sections, and they are the counting means 18 having a small number of bits.
When the full count value of is the same value. C11
Is 1 corresponding to the phase angle when the fade control is started.
It is the count value of the second phase section. Cn1 is the count value of the n-th phase section corresponding to the phase angle at which the fade control ends.

Next, in step a4, the count value C
However, it is determined whether or not the number of bits of the minority bit counting means 18 is exceeded. If there is an overflow of the number of bits, the process moves to step b5 to find the section to which the phase angle belongs. When there is no overflow of the number of bits in step b4 and when step b5 ends, the counting process similar to that in FIG. 6 is performed in step b6.

At step b7, it is judged whether or not the count number and the section have reached the final light control timing of the fade control. If so, step b
At 8, a flag indicating the completion of fade is set. When it is determined in step b7 that the final dimming timing of fade control has not been reached and when step b8 ends, phase control is performed for each phase section in step b9, and the process ends in step b10. To do.

In each of the above embodiments, the bidirectional three-terminal thyristor is used as the switching element, but it goes without saying that it may be another switching element such as a transistor. When the switching element is a transistor, it is easy to control from the conduction state to the cutoff state by the signal given to the base, so the phase angle range for phase control does not necessarily have to be the next zero cross point, It can be set arbitrarily. Further, although the counting means using the 4-bit counter as the minority bit has been described, the counting means having a larger number of bits such as 8 bits is used to further increase the frequency of the basic clock signal to perform fine control. Of course, it can be done.

[0035]

As described above, according to the present invention, a sufficient number of pulse signals for smoothly changing the dimming level of the lighting load are generated in each half cycle of the output of the AC power source, and each pulse signal is generated. The counter of the number of bits smaller than the number of bits required to express the number of pulse signals generated in a half cycle in binary number detects the time point of the phase angle corresponding to the dimming level,
The phase of the switching element can be controlled. Since the number of bits required by the counter can be reduced in this way, the brightness of the illumination load can be changed smoothly, and a small and inexpensive dimmer can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of the embodiment shown in FIG.

FIG. 3 is a waveform diagram for explaining a fade control state according to the embodiment shown in FIG.

FIG. 4 is a flow chart for explaining the operation of the embodiment shown in FIG.

FIG. 5 is a flowchart for explaining a counting process in the flowchart shown in FIG.

FIG. 6 is a flowchart for explaining the operation of another embodiment of the present invention.

FIG. 7 is a block diagram showing an electrical configuration of a conventional light control device.

FIG. 8 is a waveform diagram for explaining the operation of a conventional light control device.

[Explanation of symbols]

 11 AC power supply 12 Lighting load 13 Switching element 14 Input means 15 Minority bit control means 16 Zero-cross detection means 17 Basic clock generation means 18 Minority bit counting means

Claims (1)

(57) [Claims] 1. A dimming device that forms a closed loop by a lighting load, an AC power supply, and a switching element, controls the phase of the lighting load by the switching operation of the switching element, and continuously changes the dimming level of the lighting load. The input means that gives a dimming level that changes dynamically, and each half cycle of the output from the AC power source that drives the lighting load,
In order to divide into a plurality of divisions in which the change of the dimming level due to phase control is difficult for human beings to detect between consecutive division sections, pulse generation means for generating a pulse signal for each division section, and the plurality of the division sections in binary numbers A counter that counts the pulse signal from the pulse generating means with a predetermined number of bits smaller than the number of bits required to express it, and each half cycle of the output from the AC power supply The pulse signal is divided into a plurality of countable phase angle sections, and for each half cycle, the phase angle to be controlled corresponding to the dimming level given from the input means is among the plurality of phase angle sections. Determine which it belongs to,
A light control device comprising: a control unit that performs a count corresponding to the phase angle by a counter within the determined phase angle section and controls the phase of the illumination load.