JP3138281B2 - Dimming 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 controlling the phase of a lighting load, and more particularly to a dimming control device for performing a phase control by digitizing a phase angle.

[0002]

2. Description of the Related Art FIG. 6 shows an electrical configuration of a conventional dimming control device. The power from an AC power supply 2 for energizing a lighting load 1 such as a lighting lamp is phase-controlled by a switching element 3 such as a bidirectional three-terminal thyristor to adjust the lighting load 1 to a desired brightness. Light controlled.
The phase control of the switching element 3 is performed by a trigger signal given from the trigger output means 4 to the gate of the switching element 3. The trigger output for controlling the phase of the switching element 3 is derived from the trigger output means 4 because the clock signal from the counting clock generating means 5 is counted by the count value preset in the counting means 6. It is time. The counting operation of the counting means 6 is performed by a power supply synchronization signal generating means 7 for detecting a zero-cross point of the output of the AC power supply 2
This is performed by the control means 8 in response to the power supply synchronizing signal from. The control means 8 includes a microcomputer or the like, and sets a predetermined count value in the counting means 6 in response to the power synchronization signal from the power synchronization generation means 7 and causes the counting means 6 to start a counting operation.

That is, a counting value is set in the counting means 6 at each zero-cross point of the output from the AC power supply 2, and after counting the clock signal from the counting clock generating means 5 by the counted value, a trigger is generated. A signal for conducting the switching element 3 is generated from the output means 4. If the count value when the counting means 6 counts the clock signal from the counting clock generation means 5 is set to be large, the phase angle at which the switching element 3 starts conducting becomes large, and the AC power supplied to the lighting load 1 is increased. The power from 2 will be less,
The brightness of the illumination load 1 decreases. If the count value set in the counting means 6 is reduced, the value of the phase angle at which the switching element 3 starts conducting becomes smaller, the power supplied from the AC power supply 2 to the lighting load 1 increases, and the brightness of the lighting load 1 increases. Increase. As described above, in the conventional dimming control device, at each zero-cross point of the power from the AC power supply 2,
That is, a new count value is set in the counting means 6 every half cycle, and the phase control of the switching element 3 is started when the counting clock is counted.

[0004]

In the conventional phase control device, as shown in FIG. 6, the conducting phase angle of the switching element 3 is controlled in accordance with the count value set in the counting means 6. . When the phase angle is digitized and controlled, the higher the frequency of the counting clock signal supplied from the counting clock generating means 5 to the counting means 6, the finer the division of the half cycle of the output of the AC power supply 2, the finer the phase. It can be controlled with precision. When performing fade control in which the brightness of the illumination load 1 is gradually shifted from a certain brightness level to another different brightness level, the human eye needs to change the dimming level rather finely. Is perceived as a discontinuous object whose brightness is unstable and gives psychological anxiety or discomfort. Experiments and evaluations of existing products have shown that a power supply cycle of 60 Hz or 50 Hz requires a fine precision of 256 steps or more as a half-cycle phase angle in order to feel as a smooth fade to the human eye. I have.

In order for the counting means 6 of FIG. 6 to perform phase control with a fine precision of 256 steps or more, it is necessary to increase the frequency of the counting clock signal and use the counting means 6 composed of about 16 bits. is there. When using the counting means 6 of about 8 bits, fine precision of the phase control angle is sacrificed.

In the conventional dimming control device, when the dimming level is controlled with a high precision, the counting means 6 having a large number of bits is required, which hinders low cost and miniaturization. Further, the number of bits of the data bus and the like of the control means 8 is often constituted by the same number of bits in accordance with the number of bits of the counting means 6, which is further disadvantageous in terms of cost reduction and miniaturization. ing.

An object of the present invention is to provide a dimming control device capable of performing fine-precision phase control without increasing the number of divisions of power from an AC power supply in each half cycle as a whole. .

[0008]

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 control device that performs a switching operation of a switching element to control a phase of a lighting load at a set dimming level, each half cycle of an output from an AC power supply that drives the lighting load is divided into a first plurality. Means for determining which of the divided periods the set dimming level belongs to, and responding to the output from the determining means to determine the divided period to which the set dimming level belongs. Means for controlling switching of a switching element connected in series to the lighting load at each time of each half cycle corresponding to the set dimming level. Light control device.

The present invention also provides a dimming control device for forming a closed loop by a lighting load, an AC power supply, and a switching element, performing a switching operation of the switching element, and controlling the phase of the lighting load at a set dimming level. Means for inputting and setting the dimming level of the load, and dividing each half cycle of the output from the AC power supply for driving the lighting load into a first plurality, and determining a first count value predetermined for each of the divided periods. A counter that counts the light so as to determine which divided period the light control level set by the input setting means belongs to, and sets the light control set according to the number of times the counter has counted the first count value. A division period corresponding to the level is selected, the selected division period is further divided by a second plurality, and the counter counts a second count value corresponding to the input dimming level. When in is a switching element connected in series with the lighting load a dimming control device which comprises a means for switching control.

[0010]

According to the present invention, the dimming level set for dimming control of the illumination load belongs to any one of the periods in which the output from the AC power supply is divided into the first plurality every half cycle. Is determined. Within the period to which the switching element belongs, the switching control of the switching element connected in series to the lighting load is performed at each time every half cycle corresponding to the phase angle. Since the dimming level corresponds to the phase angle obtained by dividing the period previously divided into the first plurality into the second plurality, even if the number of divisions is the first plurality or the second plurality and is relatively small, The angle is divided by a relatively large number that is a product of the first plural number and the second plural number, can be set to a small value, and performs a smooth dimming level change by a smooth phase angle change. Can be.

According to the invention, the dimming level of the lighting load is inputted to the setting means. The half cycle of the AC power supply is divided into a first plurality, and the counter counts to a predetermined first count value for each of the divided periods. It is determined to which division period the dimming level set by the input setting means belongs, and a division period corresponding to the dimming level is selected according to the number of times the counter has counted the first count value. When the counter counts the second count value corresponding to the input dimming level within the selected divided period, the switching operation of the switching element is controlled. Since the counter counts the second count value in a period in which a half cycle of the power from the AC power supply is divided into the first plurality in advance, the counter is set with high accuracy even if the second count value is a small value. The phase control of the switching element corresponding to the dimming level can be performed.

[0012]

FIG. 1 is a block diagram showing an electrical configuration of a dimming control device according to an embodiment of the present invention. In order to control dimming of a lighting load 11 such as an incandescent lamp or a fluorescent lamp using power from an AC power supply 12, a switching element 13 for phase control is connected in series to the lighting load 11 and the AC power supply 12, and these are closed loops. Is composed. As the switching element 13, a bidirectional three-terminal thyristor or the like can be used. The output from the flip-flop 14 is given as a trigger output to the gate, which is the control electrode of the switching element 13, and the phase is controlled. The fine precision of the phase control is determined by the frequency of the counting clock signal from the counting clock generator 15. When the frequency of the counting clock signal increases, the AC power supply 1
The number of counting clock signals generated in two half cycles becomes large, and the half cycle of the AC power supply 12 can be finely divided. When the frequency of the counting clock signal is high, the counter 16 requires a large number of bits when trying to count the whole of each half cycle of the AC power supply 12, but in the embodiment shown in FIG. The counter 16 is composed of an 8-bit presettable down counter.

Each half cycle of the AC power supply 12 starts from a zero cross point at which its output voltage becomes zero, ends at the next zero cross point, and a new half cycle starts. The power supply synchronizing signal generation means 17 detects a zero-cross point of the AC power supply 12 and supplies a power supply cycle signal representing the detection result to the control means 18. A dimming level at which dimming control of the illumination load 11 is to be provided to a control unit 18 including a CPU or the like via an input unit 19. The control means 18 determines whether the set dimming level belongs to any of the periods obtained by dividing each half cycle of the AC power supply 12, and controls the output signal from the counter 16 until the period is reached. The switching means 20 is controlled to be switched so as to be given as an interrupt signal to the switch 18. The control means 18 responds to the interrupt signal from the switching means 20 and controls the counter 1 while the dimming level does not belong.
In step 6, a full count value as a first count value, that is, zero is set as a preset value. During the period to which the dimming level belongs, the control means 18 sets the second count value corresponding to the dimming level in the counter 16 as a preset value,
The switching means 20 is switched and controlled so that the output from the switching means 20 is supplied to the flip-flop 14. Thus, when the counter 16 counts the second count value, the trigger output of the switching element 13 is derived from the flip-flop 14. The switching element 13 responds to the trigger output by switching the power from the AC power supply 12 to the lighting load 11.
Give to. At the next zero cross point, in response to the power supply cycle signal from the power supply synchronization signal generation means 17, the control means 18 resets the flip-flop 14 and stops the phase control of the switching element 13.

FIG. 2 is a block diagram showing an electrical configuration of another embodiment of the present invention. Parts corresponding to those in the embodiment shown in FIG. 1 are denoted by the same reference numerals. It should be noted that the switching means 20 in the embodiment shown in FIG. The control unit 18 includes a CPU or the like, and performs various processes in synchronization with a clock signal from the basic clock generation unit 22. Power supply synchronization signal generation means 1
7 and an output from the changeover switch 21 are given as interrupt signals to the CPU, respectively.

FIG. 3 is a waveform diagram for explaining the state of phase control in the embodiment shown in FIG. 1 or FIG. FIG. 3A shows an output voltage waveform of the AC power supply 12. A half cycle period from the first zero crossing point t1 to the next zero crossing point t4 is divided at times t2 and t3,
The period is divided into three periods S1, S2 and S3. The phase of the switching element 13 is controlled, and the switching element 13 conducts during the period from time t21 to t4 in the period S2, which is indicated by oblique lines in the drawing. In order to perform such control, first, a power supply synchronization signal as shown in FIG. The control unit 18 resets the flip-flop 14 in response to the power synchronization signal. Further, it is determined whether or not the dimming level to be dimmed belongs to the period S1. In this case, since the dimming level does not belong, the counter 16 is reset to set a count value corresponding to the period S1. The counter 16 counts the counting clock signal, and supplies a signal indicating the end of the counting to the control means 18 at time t2 as an interrupt signal. Since the period S21 corresponding to the dimming level belongs to the period S2, the control unit 18 sets the counter 16 to a count value corresponding to the period S21. The control means 18 includes the switching means 2
0 or the changeover switch 21 is switched so that the output of the counter 16 is supplied to the flip-flop 14. When the counting of the period S21 ends in the period S2 in this manner, the flip-flop 14 is set, and the switching element 13 is turned on. Such a flip-flop 1
The operation of No. 4 is shown in FIG. 3 (3), and the operation of the control means 18 for setting the count value in the counter 16 is shown by hatching in FIG. 3 (4). That is, A is an operation for setting the first count value, and B is an operation for setting the second count value.

FIG. 4 is a flowchart for explaining the operation of the control means 18. At step a1, an interrupt occurs due to the power supply synchronization signal. In response to this interrupt, the control means 18 resets the flip-flop 14 in step a2.

Next, at step a3, it is determined whether or not a period following the period during the operation is a period to which a phase angle corresponding to the dimming level belongs. A count value for counting the entire period that is the first predetermined count value is calculated, and when the time corresponding to the dimming level belongs to the period, a second count value corresponding to the dimming level is calculated. .

Next, in step a4, it is determined whether or not the period in which the phase angle corresponding to the dimming level belongs, that is, the period in which the trigger output is performed. If it is not such a period, the switching means 20 or the changeover switch 21 is switched so as to be an interrupt input to the control means 18 in step a5. In such a state, the counter 16
When the counting of the first count value is completed, a counter end interrupt is generated in step a6, and the process returns to step a3.

When it is determined in step a4 that the time period is the trigger output section, the process proceeds to step a7, and the switching means 20 or the switch 21 is switched to perform trigger output. In such a state, the counter 16
When the counting of the count value is completed, the flip-flop 14 is set, and a trigger output to the switching element 13 is given. This trigger output is reset by the operations of step a1 and step a2 when the AC power supply 12 reaches the next zero crossing point.

FIG. 5 is a block diagram showing an electrical configuration of still another embodiment of the present invention. Parts corresponding to the embodiment shown in FIG. 1 are denoted by the same reference numerals. It should be noted that the trigger output of the flip-flop 14 is provided to the control terminal of the switching element 13 via the gate 24. The counting clock signal counted by the counter 16 is obtained by dividing the system clock from the system clock generating means 26 for the synchronous operation of the control means 18 by the frequency dividing means 23 to obtain a counting clock having a period of 15 μsec. Things. The power supply synchronizing signal from the power supply synchronizing signal generation means 17 and the interrupt signal at the end of counting from the counter 16 are given to the control means 18 via the control bus signal line 25. A signal for controlling the gate 24 is provided from the control means 18 via a control bus signal line 25.

The counter 16 can set a preset value of 8 bits and perform down-counting. The 4-bit CPU can be used as the control means 18 to set the preset value separately for upper 4 bits and lower 4 bits. Can be.

According to such an 8-bit counter 16, it is possible to measure time up to 3.84 ms with a counting clock of 15 μs. The frequency of the AC power supply 12 is 60H
When z, the half cycle is 8.3 ms. Therefore, by dividing a half cycle into three periods,
By using the 8-bit counter 16, it is possible to perform light control with a fine precision of 550 or more steps.

In each of the above embodiments, a bidirectional three-terminal thyristor is used as the switching element 13, but it is a matter of course that another switching element, for example, a transistor or the like may be used. When another switching element is used, a configuration for generating a gate signal for controlling the phase can be changed and realized so as to be suitable for the switching element.

The input means 19 may, of course, gradually increase or decrease the dimming level so as to perform fade control.

[0025]

As described above, according to the present invention, even if each half cycle of the power from the AC power supply is divided by a small number, the phase control of the power supplied from the AC power supply to the lighting load can be performed with fine precision. Can be. Further, even if the number of divisions per half cycle of the AC power supply is small, the dimming control can be performed by smoothly changing the phase angle. Further, since the number of divisions is small, it is easy to reduce the cost and size of the dimming control device.

According to the present invention, by setting the first count value in the counter and counting, the end of each section obtained by dividing each half cycle of the AC power supply into the first plurality can be detected. By setting the two count values, the switching operation of the switching element corresponding to the dimming level can be controlled with high precision within the period to which the dimming level belongs. In addition, since two types of counting operations can be performed by one counter, the dimmer can be further reduced in cost and size.

[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 block diagram showing an electrical configuration of another embodiment of the present invention.

FIG. 3 is a waveform chart for explaining a state of phase control in the embodiment shown in FIG. 1 or FIG. 2;

FIG. 4 is a flowchart for explaining the operation of the control means 18 in the embodiment shown in FIG. 1 or FIG.

FIG. 5 is a block diagram showing an electrical configuration of still another embodiment of the present invention.

FIG. 6 is a block diagram showing an electrical configuration of a conventional dimming control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Illumination load 12 AC power supply 13 Switching element 14 Flip-flop 15 Counting clock generation means 16 Counter 17 Power supply synchronization signal generation means 18 Control means 19 Input means 20 Switching means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05B 39/08

Claims (2)

(57) [Claims] 1. A light control device that forms a closed loop by a lighting load, an AC power supply, and a switching element, performs a switching operation of the switching element, and controls a phase of the lighting load at a set dimming level. Means for determining which of the divided periods the set dimming level belongs to, and each of the half cycles of the output from the AC power supply, In response, the divided period to which the set dimming level belongs is further divided by the second plurality, and connected in series to the lighting load at each time every half cycle corresponding to the set dimming level Means for controlling the switching of the switching element provided. 2. A dimming control device that forms a closed loop by a lighting load, an AC power supply, and a switching element and performs a switching operation of the switching element to perform phase control of the lighting load at a set dimming level. Means for inputting and setting the light level, and each half cycle of the output from the AC power supply for driving the lighting load is divided into a first plurality, so that a first count value determined in advance for each of the divided periods is obtained. A counter that performs counting, and determines to which division period the dimming level set by the input setting unit belongs,
Depending on the number of times the counter has counted the first count value, a division period corresponding to the set dimming level is selected,
The selected divided period is further divided by a second plurality,
Means for controlling switching of a switching element connected in series to the lighting load when the counter counts a second count value corresponding to the input dimming level.