JPS61228513A - Temperature controller - Google Patents

Abstract

PURPOSE:To decrease the overshoot frequency and to secure the control of temperatures with no practical problem by changing temperatures with a heating means at first when a prescribed level of temperature is detected and then changing them with delays at and after the second time after detection of the prescribed temperature. CONSTITUTION:A counter 18 is set at the value corresponding to T deg.C and a power supply is supplied. Thus the output 23 compared with a temperature detecting means 19 is set at H and a switching means 25 is turned off with the NOR output 24F of a timer 24 is set at H. Then a relay circuit 21 is closed to start energization of a resistance 2. A positive pulse is sent to the means 25 from a circuit 16 via an OR circuit 26 and an integration circuit 27. The means 25 is turned on with a delay from application of the power supply after selection of an integration constant. When the T deg.C is detected 19, the comparison output 23 is turned into L with the output of the timer 24 set at L respectively. Then the relay 21 is opened to break the energization of the resistance 2. If the T deg.C is detected 19 after the overshoot, the output 23 is set at H with the means 25 turned off. Then the output of the timer 24 is changed to H for energization. However the output of a buffer 24C is changed to H at the T deg.C and at the same time a negative pulse is produced 24D. Meanwhile the output 24F is kept at H for energization. This procedure is repeated and the control of temperatures is possible in a small range.

Description

DETAILED DESCRIPTION OF THE INVENTION A) Field of Industrial Application The present invention relates to a temperature control device used, for example, in an iron or the like.

Conventional technology Conventionally, for example, a temperature control device used in an electric iron includes a heater, a thermistor that detects the temperature of the base, and a control that controls the heater via a relay circuit based on the output of the thermistor. A circuit that improves the thermal responsiveness of the thermistor to reduce the width of temperature change in a stable state and reduce temperature detection errors is disclosed, for example, in Japanese Patent Application Laid-Open No. 112598/1983. However, if the width of the temperature change in the stable paddle is reduced in this way, the number of times the relay contact opens and closes per unit time will increase, which will shorten the service life of the relay contact, and eventually cause poor continuity of the relay contact. There was a risk that contact welding would occur and shorten the life of the iron. In order to solve this problem, a means (for example, a delay circuit connected between the control circuit and the relay circuit) that can arbitrarily vary the width of the temperature change is provided, and from the above-mentioned width of the temperature change, It is conceivable to make the temperature change variable within a range determined by taking into consideration the practically acceptable range of temperature change and the service life of the relay contact, but this is preferable because the overshoot that occurs after power is turned on is even larger. It wasn't something.

C) Problems to be Solved by the Invention The present invention has been determined in consideration of the above-mentioned drawbacks, without increasing the overshoot, and in consideration of the practically acceptable range of temperature change and the service life of the relay contact. An object of the present invention is to provide a temperature control device that can be set to a range of temperature changes.

2) Means for solving the problem The present invention is a temperature control device equipped with a control means for controlling the heating means via a relay circuit, wherein the control means controls the switching timing of the heating means from the second time onwards. The first switching detection means is provided to delay the switching timing from the first switching timing.

E) Function Since the present invention is configured as described above, the first switching of the heating means is performed when the detection means detects a predetermined temperature, and the second and subsequent switching of the heating means is performed when the detection means detects a predetermined temperature. This is done a predetermined time after the temperature is detected.

f) Embodiment An embodiment of an electric iron equipped with the temperature control device of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view of an electric iron, in which [1] is an aluminum pace (heated body), [21 is a heater C heating means embedded in the pace], and +31 #- is the pace f1). (4) is a thermistor closely fixed to the pace H in the vicinity of the vaporization chamber; (5) is the above-mentioned pace! 1) is a steam hole provided on the bottom of the spacer and communicates with the vaporization chamber (3), and (6) is an iron cover provided above the space ill, which is made of heat-resistant material such as silicone rubber and communicates with the vaporization chamber (3). A cylindrical communication member (7) is provided that allows the rubber to rise. (8) is the iron cover (6)
) is a handle body fixed to the top surface of the bar-shaped machine part (8
A), has a guide part (8B) at the bottom, and a support part (8C) that connects the grip part (8A) and the guide part (8B) at the rear part.
is formed. (9) is a tank which is removably housed between the iron cover 16) and the guide part (8B) and stores water, and is provided with a steam nozzle (1) on the bottom that communicates with the communication member (7).

Figure 2 is a perspective view of the grip part (8A), (u) UP switch for setting the desired temperature of I/i pace il+ from low to high, 0zu is the DOWN switch for setting from high to low, (13
) (131... is a display that displays the set temperature.

Figure 3 is a schematic electrical circuit diagram, row 04 is an AC power supply,
Qllf) is the direct power supply circuit, (1d is the initial circuit, which outputs a positive pulse when the AC power supply H is turned on. C1η is a setting means that maintains a predetermined value depending on the set temperature; σP DOWN・F3 is applied to the counter circuit 0→, the σP input terminal, and the DOW'N input terminal of the counter circuit.
It is composed of the σP switch (11) and the DOWN switch (1 and 2). and 'DOWN switch (when +21 is closed, a predetermined value corresponding to high to low is output. The top is the aforementioned e-pace 1]). ) and A/D
It consists of a conversion circuit Q■. D1) is a relay circuit, which includes a contact (21A) connected in series to the heater (2), a coil (21B) electromagnetically coupled to the long contact, and a relay transistor (21C) that controls energization to the coil. It consists of. (221 is a control means that controls the heater (2) via the relay circuit (211) based on the setting means (171) and the detection means (+i), and the output of the setting means (17) and the detection means (+1). (23), timer means (24) for delaying the output of the comparison means, and first switching detection means for disabling the timer means.The comparison means f2 )'
9 is a setting means (the set temperature by lη is the detection means f+gK
The timer means (24) outputs an ``HH level signal when the temperature is higher than the detected temperature, and an @L# level signal when the temperature is lower than the detected temperature.
24A) and the comparison means (
(2) The first and second three-state buffer circuits (2) have control terminals of opposite poles that are given the output of
4B), ('24G), and a one-shot circuit ('24G) that is given the output of the second three-state buffer circuit (z4c).
24D) and a second three-state buffer circuit (24C
) and the output of the one-shot circuit (24D), and the output of the first three-state buffer circuit (24B) and the AND circuit r24111)
It consists of a NOR circuit (24F) which is given an output of . Each of the three-state buffer circuits ('24
B) (24G) has its output terminal grounded through a resistor,
It is set so that the output terminal becomes 'L' level when the noi impedance stops.The one-shot circuit (
24D) outputs a negative pulse of a predetermined width in synchronization with the rising edge of the input pulse. The first switching detection means (
The initial circuit (OR circuit t261 given the output of II and the input of σP Do■ counter circuit [9)
The output of is given to the S input terminal via the integrating circuit 4η,
The output of the comparing means (23) is connected to the base of a flip-flop (state switch) ('zsA) which is given to the R input terminal, and the α output terminal of the flip-flop is connected to the base of the flip-flop, and the collector is connected to the i1, second three-state buffer circuit r2
4B) and a switching transistor (2sB') connected to the control terminal of (24C).

Figure 4 shows the time chart, (A) is the base (1)
(B) is the detected temperature of thermistor (4), (
C) is the input signal waveform of the S input terminal of the flip-flop (f'sA), (to) is the R of the flip-flop (25A)
The input signal waveform of the input terminal, ■ is a flip-flop (25
(7) is the output signal waveform of the α output terminal of the first three-state buffer circuit (24B), (G
) is the output signal waveform of the second three-state buffer circuit (24C), (b) is the output signal waveform of the one-shot circuit (z4D'), cx) is the output signal waveform of the AND circuit (24FX), C″f′) is the output signal waveform of the NOR circuit (24F).

Next, the operation of the above configuration will be explained based on FIGS. 1 to 4. First of all, UPDOWI! When the AC power supply 04 is turned on with the output of the i-counter circuit θ rumored to be, for example, 200C1' (corresponding predetermined value held), the comparison means (to) outputs a 1P level signal, so the flip-flop (25A ), the P level signal is given to the R input terminal of the
”The level signal is output and the switching transistor (25B
) is turned OFF. When this switching transistor (25B) becomes CIF'F, an "H" level signal is given to each control terminal of the first and second three-state buffer circuits (24B") (24C), so the first three-state The output of the buffer circuit (24B) becomes high impedance, and the output of the second three-state buffer circuit (24C) outputs an L" level signal in response to the output of the inverter circuit (24A). As mentioned above, the first three-state buffer circuit (24B') outputs the "'L# level signal" when the impedance is high.The AND circuit (24K) outputs the "L" level signal. Since it outputs, the NOR circuit (24F') is 1H"
When the level signal is output, the relay transistor (21C) turns on, the contact (21A) closes, and the heater (21) starts to be energized.Also, the positive pulse from the initial circuit f+Ij is output from the OR circuit. , integral circuit (271
Since it is given to the S input terminal of the flip-flop (2sA) via 25A) will output a @H” level signal from the α output terminal, and the switching transistor (
25B) is Olr. This switching transistor (25
B) turns on, the first three-state buffer circuit (
z4B) now corresponds to the output of the inverter circuit (24A), but the inverter circuit FJ (:4A) is still 1
Since it is outputting a 2-level signal, it continues to output an i"L' level signal, and the second three-state buffer circuit (2
4G) output becomes high impedance. This second three-state buffer circuit (24G), like the first three-state buffer circuit (24B), outputs a ``L'' level signal when there is no impedance.
There is still no change in output. Therefore, heater (2)
The current supply to the base f11 is maintained, and the temperature of the base f11 increases.

The temperature of the base Il) increases and the thermistor (4)
When 200°C is detected at time tl in the figure, the output of the comparison means □□□ changes to an "L" level signal, and its power is "
"L#L# level signal. Therefore, the relay transistor (2xc) is 0IFFI, and the contact (21m) is...
When the heater (2) is opened, power to the heater (2) is quickly cut off. base I
Even if the power to the heater (2) is quickly cut off, the temperature of
The temperature often rises to a predetermined level due to residual heat, and then gradually decreases from there. The maximum temperature rise of the base (1) after turning on the AC power supply 04 is somewhat higher than the maximum temperature rise in a stable state (overshoot). This is because there is.

As a result, the temperature of the base +1) decreases, and the temperature of the thermistor (4) decreases.
) detects 200°C at time t2 in Figure 4, the output of the comparator changes to a 1H'' level signal, so
An "H" level signal is applied to the R input terminal of the flip-flop (25A), and the output of the a output terminal changes to a 1L" level signal. Therefore, the output of the first three-state buffer circuit (24B) is The second three-cheat circuit (24C) outputs a 1L" level signal in response to the output of the inverter circuit (24A), so the output of the NOR circuit (24F) is
The signal changes to "H" level, and power supply to the heater (2) is started.

Next, when the temperature of the base +11 rises and the thermistor (4) detects 200C at time t3 in FIG.
The output of the three-state buffer circuit (24C) is @L”
``H#H# level signal from the level signal. Then,
Since the one-shot circuit @ (24D) outputs a negative pulse of a predetermined width in synchronization with the change in this signal, the NOR circuit (24F
) is the generation time of this negative pulse (t3 to t in Figure 4)
During 4), the @H# level signal is held, and the heater (2) is also energized during this period. Then, when the output of the one-shot circuit (24D) returns to the -LH- level signal, the output of the NOR circuit (24F) changes to the "r level signal, and the power to the heater (2) is cut off, and the base +1) The temperature gradually decreases until the thermistor (4) detects 200°C at time t5 in Figure IE4.After that, the temperature of the heater is 0N from t2 to t6 in Figure 4.
- You will be manipulating the OIFF cycle.

Then, close the DOWN switch 02 and set the temperature to 20.
For example, if the temperature is changed from 0°C to 150°C at ts' in Fig. 4, the a output terminal of the flip-flop (25A) will change to the @H'' level signal 0.5 seconds after the time t5. 1 three-state buffer circuit (2
4B) outputs a ``H'' level signal in response to the output of the circuit (24A), and the output of the second three-state buffer circuit (34C) becomes high impedance. Therefore, the output of the NOR circuit (241F) remains at 1L#, a step signal, and the current to the heater (2) remains cut off. Face down, base f1
) temperature gradually decreases below Kll,,? -Mr. (4) is 15
When 0°C is detected, the output of the comparator (23) changes to the @E'' level signal, so the @R'' level signal is given to the R input terminal of the flip-flop (25A), and the output of the Q output terminal becomes ''. Therefore, the output of the first three-state buffer circuit (24B) becomes zero impedance, and the second three-state buffer circuit (24C) changes to the output of the inverter circuit (24A). Since @I, # level signals are output, the output of the NOR circuit (24F) changes to a 1P level signal, and energization of the heater +21/% is started.After that, from 150, as shown in Fig. 4. t2 at
The 0N-011'F cycle of the heater (2), which is substantially the same as that at ~t5, is repeated.

Next, close the σP switch (11) and set the temperature to 150℃.
For example, if the temperature is changed from 200°C to 200°C using tlJ in Fig. 4, the Q output terminal of the 7 lip-flop (25A) changes to an “H” level signal 0.5 seconds after this time t14, so the first three cheatノ (Zuffa circuit (2)
4B) corresponds to the output of the inverter circuit (24A).
The second three-state buffer circuit (24C) outputs a L'' level signal, and the output of the second three-state buffer circuit (24C) becomes a zero impedance. Therefore, the output of the NOR circuit (24F) changes to an @H'' level signal, and the output to the heater (2) Power supply will start. Therefore, when the temperature of pace +1) rises and the thermistor (4) detects 200°C, t in Fig. 4 increases.
As at time 1, the power to the heater (2) is immediately cut off, and the temperature of the pace (1) drops and the thermistor (4) detects 200°C again, after which the temperature at t in Fig. 4 is reached.
0N-O11' of heater (2) similar to 2-t5? You'll be repeating the cycle.

Next, a method for determining the width of the negative pulse output from the one-shot circuit (24D) will be described.

First, in the above configuration, when the width of the negative pulse was 0 seconds and the set temperature was 200°C, the on time of the heater in a stable state, the on-off 1 cycle time, and the width of temperature change were measured. For example, if we assume that the lifespan of the relay is 200,000 times, the safety factor is 2, and the actual lifespan of the relay is 100,000 times, then the lifespan of the iron will be 722 hours, which is 1500 hours, which is generally the target lifespan of irons. 7
It will last for 78 hours.

Next, the width of the negative pulse is set to 4 seconds and 5 seconds, and in the above case and this case, the life of the iron when the width of the negative pulse is 4 seconds is 1444 hours, and the life of the iron is 1444 hours when the width of the negative pulse is 5 seconds.
777 hours, compared to 1500 hours in the former case.
In the latter case, there was a shortage of 56 hours, and in the latter case there was a surplus of 277 hours. Further, the temperature change width is 10°C in the former case and 12°C in the latter case, which is significantly improved compared to the 20-32°C temperature change width that occurs in the bimetal type.

Therefore, it is sufficient to set the one-shot circuit by setting the width of the negative pulse to 5 seconds.

The reason why the timer means of the present invention is set to operate only when power is cut off to the heating means is that although the rate of temperature rise is not greatly affected by the ambient temperature, the rate of temperature fall is very dependent on the ambient temperature. This is because if the timer means is used to start energizing the heating means, a situation may occur in which the range of temperature change varies greatly depending on the ambient temperature.

g) Effects of the Invention The present invention provides a temperature control device equipped with a control means for controlling the heating means via a relay circuit, and the control means controls both the first switching of the heating means and the second and subsequent switching of the heating means. Since this device is equipped with an initial switching detection means that changes the switching timing, it is possible to detect temperature changes determined by taking into account the practical range of temperature changes and the service life of the relay contacts, without increasing overshoot. It is possible to set the width.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of an electric iron equipped with the temperature control device of the present invention, FIG. 2 is a perspective view of the grip of the electric iron, FIG. 3 is an electric circuit diagram of the electric iron, and FIG.
The figure also shows a time chart for an electric iron. (2)...Heating means (heater), αη...Setting means, 111...Detection means, 嬶)...Relay circuit, (
(b)...control means, (iv)...comparison means, (2...
Timer means, (2I19... first switching detection means, (2
5A)...Status switch. Applicant: Sanyo Electric Co., Ltd. and one other representative: Shizuo Sano, patent attorney Figure 1 Figure 2 Figure 1 F Figure 3

Claims (4)

[Claims] (1) Based on a heating means for heating an object to be heated, a setting means for holding a predetermined value according to a set temperature, a detecting means for detecting the temperature of the object to be heated, and the setting means and the detecting means, and control means for controlling the heating means via a relay circuit, and the control means includes first switching detection means for delaying the second and subsequent switching timing of the heating means from the first switching timing of the heating means. Features temperature control device. (2) The first switching detection means has a state switching device that is set by operating the setting means or turning on the power and reset from the first switching to the second switching of the heating means. The temperature control device according to scope 1. (3) The control means includes a comparison means for comparing the setting means and the detection means, a timer means for delaying the output of the comparison means, and the first switching detection means for disabling the timer means. The temperature control device according to claim 1, characterized in that: (4) The temperature control device according to claim 3, wherein the timer means operates when power is cut off to the heating means.