JPH0578127B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a relay driving device using a microcomputer to control the electrodes of equipment used in general households.

Conventional configurations and their problems Conventionally, when irons, rice cookers, etc. use microcomputers to drive relays and control heater power, the microcomputer (hereinafter referred to as microcomputer) programs are often run in synchronization with the power supply. , in that case the relay drive phase is fixed,
The drawback was that the durability of the relay contacts was greatly shortened.

In other words, the positive 90° of one cycle of the power supply
A device that opens and closes in the phase always opens and closes in that phase, so from the point of view of the contact, it means that DC is being opened and closed at the highest voltage, and transition of the contact is likely to occur, and as a result, the contact was reducing the lifespan of. Recently, in order to solve this drawback, a method has been proposed in which one cycle is divided and the drive phase of the relay is sequentially changed, but the program is complicated and the number of times the relay is opened and closed is small (for example, irons). Then, a shift in the drive phase still occurs.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of the conventional relay drive method and prevents the life of the relay contacts from decreasing.

Composition of the Invention The relay driving device of the present invention includes: power synchronization pulse generation means for generating a power synchronization pulse every half cycle of the power supply in synchronization with the power supply cycle; counter means for inputting and counting the power supply synchronization pulse; a timing means for outputting a synchronization pulse asynchronously; a reading means for reading only a specific digit of the numerical value of the counter means according to the output of the timing means; and a time conversion means for converting the value read by the reading means into time; The time converter includes a delay means for delaying and outputting the power synchronizing pulse from the displacement point by a time set by the time converting means, and a relay driving means for driving a relay by the output of the delay means. The means divides a half cycle of the power supply period and makes each phase correspond to a specific digit value of the counter means, and the delay means delays the power synchronization pulse from a positive displacement point and from a negative displacement point. The opening and closing phases of the relay contacts are alternately repeated for each positive and negative polarity of the AC power supply by alternating with delays from the displacement point, and the phase that drives the relay is randomly displaced within one cycle of the power supply cycle. .

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a specific circuit diagram showing a relay drive device of the present invention when used in an iron, and FIG. 2 is a block diagram showing the configuration thereof.

In FIGS. 1 and 2, 1 is a commercial power source, 2 is a heater, and 3 is a relay contact. As shown in FIG. 1, the power source for the circuit is generated by half-wave rectifying an AC power source 1 and smoothing it with a capacitor 4. This DC power supply becomes the power supply for the microcomputer 5. Reference numeral 6 denotes a power synchronizing pulse generating means that generates a pulse every half cycle of the power supply in synchronization with the power supply cycle, and includes a resistor 6a and a diode 6b.
Connect as shown in the figure and send the output to S of microcontroller 5.
Put it in the input. Reference numeral 7 denotes a timing means asynchronous to the power supply, and in the embodiment, a temperature detection circuit is shown. That is, a bridge circuit of a resistance thermistor 9 is connected to the input terminal of the comparator 8, and the
The output terminal of is inputted to the I input of the microcomputer 5.

Reference numeral 10 denotes a relay driving means, which consists of a relay coil 11 for controlling the contact 3 and a transistor 12 connected thereto, and is operated by the zero output of the microcomputer 5.

Microcomputer 5 consists of four blocks.
counter means 13 for counting power supply cycle pulses;
A reading means 14 for reading a specific digit of the counter means 13, a time conversion means 15 for converting the read value into time, and a delay means 16 for outputting a delayed output by that time from the displacement point of the power synchronization pulse.
It consists of The counter means 13 is a 4-digit counter as shown in FIG. 3, and counts the power frequency of 50 Hz to create a timer up to 160 seconds. That is, the lowest digit counts five power synchronization pulses and carries up, increasing the 0.1 second digit.

The reading means 14 reads only the 0.1 second digit value of the counter means 13 at the output timing from the timing means 7. The read numerical value is converted by time conversion means 15. At this time, the conversion method is T=(reading value)×<ms>. That is, since the read value changes from 0 to 9, the output T of the time conversion means 15 changes from 0 to 9.
It changes up to ms. This corresponds to a value obtained by dividing the half period of the power supply into 10, and each phase is counted by the counter means 13.
It corresponds to numerical values in the digits of 0.1 seconds. Delay means 1
6 operates the relay driving means 10 with a delay of T time from the rising edge of the power synchronization pulse.

In the above configuration, the opening/closing operation of the relay when controlling the temperature of the iron will be explained.

When the power is turned on and the microcomputer 5 starts operating, a power synchronizing pulse is input to the S input (see FIG. 4), and the counter means 13 counts the number of pulses as described above. On the other hand, the base surface temperature of the iron is detected by the thermistor 9, and if it is lower than the set temperature, the output of the comparator 8 becomes "L". This signal is input to the microcomputer 5, but its timing is completely unrelated to the power supply cycle and is determined by the temperature change state of the thermistor 9. At this timing, the reading means 14 operates and reads the 0.1 second digit of the counter means 13.

For example, if this value is "2", the time conversion means 15 calculates 2×1=2 and instructs the next delay means 16 to set the delay time to 2 ms. Delay means 1
6 receives this instruction and outputs a relay drive signal from the 0 port 2 ms after the rise of the power synchronization pulse (time A in FIG. 4). This is at point 2 in the power supply phase. Then, the contact 3 of the relay closes and current flows to the heater 2, increasing the temperature of the base surface of the iron. As the temperature of the base surface rises, the temperature of the thermistor 9 also rises, and when the set temperature is exceeded, the output of the comparator 8 becomes "H". This signal is input to the microcomputer 5, and the 0.1 second digit is read again at this timing (asynchronous to the power cycle). For example, if this read value is "7", the same process as described above is performed and the signal that stops the relay drive 7ms after the S input A is set to 0.
Output from the port. As a result, relay contact 3
is opened and power supply to the heater 2 is stopped. The phase at this time is the 7 phase of the AC power supply.

In this way, the contact 3 of the relay repeats opening and closing, but the negative phase is followed by the positive phase, and so on, and the opening and closing phases of the contact are repeated alternately, controlling the base surface to the set temperature, and the relay The phase in which the contacts 3 open and close changes randomly during the half cycle of the power supply, and is not biased toward a specific phase. In the above embodiment, the polarity of the power supply is set to a phase that changes when the contact 3 is closed and opened, but it goes without saying that the polarity of the power supply can be changed when the contact 3 is opened and closed. .

Effects of the Invention The relay driving device of the present invention reads only the numerical value of a specific digit of the counter means by the timing means that outputs the output asynchronously with the power synchronization pulse generated every half cycle of the power supply. Since the relay is driven by alternating between delaying the power synchronization pulse from the positive displacement point and delaying it from the negative displacement point, the opening/closing phase of the relay contact is is determined by the timing of reading the numerical value of a specific digit of the counter means, so it can change randomly within the inverse period of the AC power supply and is not fixed at one point, and the positive and negative polarities of the AC power supply are alternately repeated. Therefore, transfer of the contacts can be eliminated, and reduction in the life of the contacts can be prevented. Furthermore, the program is simpler than that of changing the order of the opening/closing phases of the contacts, and it is possible to prevent the opening/closing phases from shifting even if the number of openings and closings is very small.

[Brief explanation of the drawing]

FIG. 1 is a specific circuit diagram showing an embodiment of the present invention;
FIG. 2 is a block diagram showing the components, FIG. 3 is a configuration diagram of the counter means, and FIG. 4 is a diagram explaining the opening/closing phase of the relay. 6...Power synchronization pulse generation means, 7...Timing means, 10...Relay drive means, 13...Counter means, 14...Reading means, 15...Time conversion means, 16...Delay means.

Claims (1)

[Claims] 1. A power synchronization pulse generating means that synchronizes with the power supply cycle and generates a power supply synchronization pulse every half cycle of the power supply;
a counter means for inputting and counting the power synchronization pulse; a timing means for outputting the power synchronization pulse asynchronously; and a reading means for reading only a specific digit of the numerical value of the counter means based on the output of the timing means; a time conversion means for converting the value read by the reading means into time; a delay means for delaying and outputting a value from the displacement point of the power synchronization pulse by a time set by the time conversion means; and an output of the delay means. relay driving means for driving the relay according to the power source, the time converting means dividing a half cycle of the power supply period and making each phase correspond to a specific digit value of the counter means, and the delay means driving the relay according to the power source synchronization. A relay driving device that alternately delays a pulse from a positive displacement point and delays a pulse from a negative displacement point.