JPH0448076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an iron using a relay as a temperature control means.

BACKGROUND TECHNOLOGY Conventionally, in many irons that have been widely used, the temperature is controlled by turning on and off electricity to a heater by turning on and off a bimetal. However, in recent years, temperature sensors have become difficult to adjust and manage due to design and manufacturing considerations, the poor temperature response of bimetals, and the recent development of temperature sensors. The number of irons that detect the temperature of the base and control the temperature by turning on and off a relay based on the output of this temperature sensor is increasing. Furthermore, recently, irons with a safety design have been developed that, if the iron is left energized, the current path to the heater is cut off after a predetermined period of time.

Problems to be Solved by the Invention The present inventors have realized the iron as described above by mounting a microcomputer and a power supply voltage detection circuit. The microcomputer recognizes the time by counting changes in the output of the power supply voltage detection circuit, turns off the relay if the iron has been left unattended for a predetermined period of time, and prevents it from turning on again if the iron is left unattended. However, in such a case, the change in the output of the power supply voltage detection circuit must be constantly detected by a microcomputer in order to count the predetermined time, resulting in the following problem. That is, the microcomputer captures the edges of the output changes of the power supply voltage detection circuit that occur in the power supply cycle, and performs other processing on the intervals between the edges of the output changes. The processing includes drive signal output processing for driving the relay, and if simple processing were performed, the drive signal output timing would be the same with respect to changes in the output of the power supply voltage detection circuit. Changes in the output of the power supply voltage detection circuit always occur in the same phase of the power supply voltage, so the relay drive signal is output in the same phase of the power supply voltage, and the relay operation is almost the same with respect to the phase of the power supply voltage. It becomes a phase. If the relay continues to operate in the same phase of the power supply voltage, the wear of the contacts will increase rapidly, resulting in a problem that the lifespan of the relay will be extremely shortened.

The present invention solves these conventional problems and provides an iron with a long relay life.

Means for Solving the Problems In order to solve these problems, the present invention has the following features:
A power supply voltage detection circuit, a relay for heater energization control connected between the power supply and the heater, a power supply voltage detection circuit that outputs a signal in synchronization with zero volts of the power supply voltage, and an output of this power supply voltage detection circuit. a timekeeping means that receives the signal and starts timekeeping and counts up to an arbitrary point in time between the signals output from the zero volt signal generation circuit; and after the timekeeping of the timekeeping means is completed;
The apparatus also includes relay drive signal output means for outputting a signal for driving the relay when the temperature drops.

Effects The effects of this configuration are as follows.
First, the power supply voltage detection circuit outputs a signal synchronized with zero volts of the power supply voltage. The relay drive signal output means drives the relay at any point between the signals of the power supply voltage detection circuit, that is, at any point between the power supply voltage zero volt and the next zero volt. It is not possible to output a signal for this purpose. Therefore, even if the relay driving means attempts to drive the relay due to a drop in temperature, the relay driving signal will not be output unless it is at an arbitrary point between zero volts and zero volts. In this way, the point at which the relay of the relay drive means that outputs the relay drive signal every time the temperature decreases can be turned on at any point between zero volts, and the point at which the relay is turned on is one point of the power supply voltage. I can't concentrate on anything.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a power supply voltage detection circuit, which includes resistors 2 and 3 and a microcomputer 4 (hereinafter referred to as microcomputer). This power supply voltage detection circuit 1 outputs a signal in synchronization with zero volts of the power supply voltage, as will be described later. 5 is a timing means, which is realized by the program of the microcomputer 4. 6 is a relay drive signal output means, which is also realized by the microcomputer 4. 7 is a relay drive circuit, 8
is a relay, and a relay drive circuit 8 is operated by a signal from the microcomputer 4, which turns it on and off.
Reference numeral 9 denotes a heater whose energization is controlled by turning the relay 8 on and off to heat the base of the iron. 10
is a thermistor attached closely to the base of the iron, and is a sensor that detects the temperature of the base. 11 is a temperature detection circuit, thermistor 1
This is a circuit that converts temperature information sensed at 0 into an electrical signal. Further, 12 is a constant voltage circuit that forms a power supply voltage for the microcomputer 4, etc., and 13 is a power supply.

FIG. 2 is a circuit diagram showing the power supply voltage detection circuit 1 including the internal circuit of the microcomputer 4, and FIG. 3 shows the voltage waveform at the terminal 14 of the microcomputer 4 and the output waveform of the power supply voltage detection circuit. In Figure 2, Micro 4
Without the built-in diodes 15 and 16, the voltage waveform at the terminal 14 would be as shown by the dotted line in FIG. 3a, with the ground terminal 17 of the microcomputer 4 as a reference. This dotted line waveform shows the constant voltage circuit 12 at 100V AC.
It is a superimposed DC voltage (about 5V) divided by a resistor, resulting in a slightly asymmetrical waveform. but,
In reality, the voltage at the terminal 14 is controlled by the clamp diodes 15 and 16 inside the microcomputer 4.
The third
The waveform will look like the solid line in figure a. When this solid waveform voltage is applied to the terminal 14, the two comparators 17 and 18 and the NOR circuit 19 as shown in FIG.
Accordingly, terminal 2 is applied only at the intermediate potential of this waveform.
0 output becomes high level. Therefore, this power supply voltage detection circuit 1 outputs a high level only near zero volts of AC 100V, and its output waveform becomes a pulse as shown in FIG. 3b. This pulse will hereinafter be referred to as a zero volt pulse. This zero volt pulse occurs approximately once every 8.3ms when the power supply frequency is 60Hz.
Occurs twice. Therefore, the microcomputer 4 can know the passage of time by counting the number of zero volt pulses. FIG. 4 is a flowchart of the program of the microcomputer 4, which corresponds to the clock means 5 and the relay drive signal output means 6. Hereinafter, the operation of the circuit shown in FIG. 1 will be explained based on FIG. 4. First, when the power is turned on and the program of the microcomputer 4 is started, zero is assigned to the variable a, and then a zero volt pulse is detected. This zero volt pulse detection involves waiting until a pulse is generated when there is no zero volt pulse, and when a pulse is generated, it is confirmed and the next operation is started. Once the zero volt pulse has been detected, it is determined whether there is a command to turn the relay on or off. This relay ON/OFF drive command is issued based on the microcomputer 4's determination when there is no relay drive command. If there is no relay drive command, the microcomputer 4 receives temperature information of the iron base from the temperature detection circuit 11, determines whether this temperature is higher or lower than a predetermined temperature, and issues a relay ON or OFF drive command as necessary. issue. When a command to turn the relay on or off is issued, a zero volt pulse is detected again and the timer starts timing operation. The timing operation is realized by delaying the number of times equal to the value of the variable a. A delay causes a time delay by repeating a program command that does not affect other programs several times, and in this embodiment, one delay causes a time delay of about 0.55 ms. Variable a is incremented by 1 each time a relay drive command is issued, and its value is held until the next relay drive command is issued. However, a should not exceed 14. Microcomputer 4 assigns variable a to variable b, and each time delay is performed, b
Subtract 1 and continue this until b becomes zero. However, if b is zero from the beginning, the delay is not performed even once. The microcomputer 4 sends a relay drive signal based on the relay drive command to the output terminal 19 of the microcomputer 4 when b becomes zero. The relay drive signal thus output is output at timing 15 as shown in FIG. In addition, in this example, the relay drive signal output timing is divided into 15 parts of 1/2 of the power supply cycle, and whether it is the positive phase or the negative phase of the power supply voltage depends on the naturally occurring timing. I'm leaving it to myself. In other words, whether the iron has a positive phase or a negative phase is determined by the timing of the rise and fall of the base temperature of the iron, and since the temperature rise and fall varies in various ways, if the iron is used for a long period of time, The probability becomes 1/2. Therefore, the drive timing of the relay is equally assigned to any phase of the power supply voltage, and is not concentrated at one point.

Effects of the Invention As described above, according to the present invention, any voltage between the signals of the power supply voltage detection circuit that outputs a signal synchronized with zero volts of the power supply voltage, that is, between the zero volts of the power supply Since relay drive signal output means is provided to turn on the relay at a certain point, the point at which the relay is turned on is averaged with respect to the phase of the power supply voltage, and the life of the relay can be extended.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Figure 2 is a circuit diagram of the power supply voltage detection circuit, Figure 3 is a waveform diagram of each part of the power supply voltage detection circuit, Figure 4 is a flowchart of the microcomputer program,
FIG. 5 is an explanatory diagram showing relay drive signal output timing. 1... Power supply voltage detection circuit, 5... Timing means, 6
... Relay drive signal output means, 8 ... Relay, 9
……heater.

Claims (1)

[Claims] 1. A relay for heater energization control connected between the power supply and the heater, a power supply voltage detection circuit that outputs a signal in synchronization with zero volts of the power supply voltage, and a timer that starts counting upon receiving the output of this power supply voltage detection circuit. and a timer for counting up to an arbitrary point in time between the signals output from the zero volt signal generating circuit;
An iron comprising relay drive signal output means for outputting a signal for driving the relay after the time measurement by the time measurement means has finished and when the temperature has decreased.