JPH0229000B2 - AIRON - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in an iron capable of displaying an appropriate temperature state.

[Technical background of the invention and its problems]

Some irons have an iron base that is heated by a heating element, which has an appropriate temperature range that includes a certain allowable temperature range above and below the set temperature Th, which is set according to the material of the cloth being ironed. Some devices are designed to turn on a suitable temperature lamp when the temperature falls within the above-mentioned suitable temperature range.

However, in order to improve the temperature control performance of the iron itself or to prevent damage to the cloth due to overheating, the above-mentioned suitable temperature range is generally set narrowly.
Therefore, when a temporary load change occurs, the temperature of the iron base deviates from the appropriate temperature range. For example, in ironing work,
When you iron a cloth after it has been washed and dehydrated, the temperature of the iron base temporarily drops and falls out of the appropriate temperature range. However, since a drop in temperature to this extent poses almost no practical problem, the ironing operation may be continued. In this state, the appropriate temperature lamp is off. Since it is not possible to determine whether this phenomenon of turning off the appropriate temperature lamp is due to the above-mentioned temporary temperature drop or a significant temperature drop, the user has to wait for the appropriate temperature lamp to turn on.

[Purpose of the invention]

The present invention was made based on the above circumstances, and its purpose is to maintain the appropriate temperature display even if the temperature of the iron base temporarily falls below the appropriate temperature range, and to improve the ironing work. The purpose of this invention is to provide an iron that can improve efficiency.

[Summary of the invention]

In the iron of the present invention, the first feedback resistor is connected to both ends of the first comparator that determines whether the temperature of the iron base is low or not, and the first feedback resistor is connected to both ends of the first comparator that determines whether the temperature of the iron base is high or not. A second feedback resistor having a resistance value greater than that of the first feedback resistor is connected to both ends of the second comparator.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows a temperature control circuit for an iron according to an embodiment, in which a temperature setting variable resistor 1, a resistor 2, and a thermistor 3 with a negative characteristic as a temperature-sensitive resistance element are connected between the V _CC terminal, which is a current power source, and the ground. They are connected in series in this order. The thermistor 3 detects the temperature of the iron base 4 heated by a heating element (not shown). Further, resistors 5, 6, 7, and 8 are connected in series in this order between the V _CC terminal and the ground.
The resistance values of the resistors 5 and 8 are set equal at R _O1 , and the resistance values of the resistors 6 and 7 are set equal at R _O2 . The connection point D between the resistors 5 and 6 is connected to a first comparator 9.
The connection point E between the resistors 7 and 8 is connected to the inverting input terminal (-) of the second comparator 10. Further, the connection point S between the resistors 6 and 7 is connected to the inverting input terminal (-) of the third comparator 11. The connection point P between the resistor 2 and thermistor 3 is connected to the inverting input terminal (-) of the first comparator 9, and the non-inverting input terminal (+) of the second and third comparators 10 and 11. is connected to. A first feedback resistor 12 is connected between the output terminal of the first comparator 9 and the non-inverting input terminal (+), and a first feedback resistor 12 is connected between the output terminal of the second comparator 10 and the non-inverting input terminal (+). A second feedback resistor 13 is connected.

Further, the V _CC terminal is connected to the output terminal of the first comparator 9 via a resistor 14 and a first light emitting diode 15 for indicating a high temperature in series, and a resistor 16 and a second light emitting diode for indicating a high temperature are connected in series. 17
are connected in series to the output terminal of the second comparator 10. Also, connect NPN between the V _CC terminal and ground.
A series circuit of a resistor 19 and a third light emitting diode 20 for displaying the appropriate temperature is connected through a transistor 18. A resistor 21, a Zener diode 22 with the polarity shown, and a resistor 23 are connected in series between the V _CC terminal and the ground.
A base bias circuit 24 is connected to the base of the transistor 18 by connecting the connection point between the transistor 18 and the resistor 23. The connection point between the resistor 21 and the Zener diode 22 in the base bias circuit 24 is connected to the output terminal of the first comparator 9 via a diode 25 in the forward direction, and the diode 2
6 in the forward direction to the output terminal of the second comparator 10. The third comparator 11 sends out a high level output as an ON signal for the heating element.

In such a configuration, the voltage V _S at the connection point S
is 1/2·V _CC , the voltage V _D at the connection point D is V _S +ε, and the voltage V _E at the connection point E is V _S −ε. However, ε is R _O2 ·V _CC /2 (R _O1 + R _O2 ).

Now, set the set temperature Th with variable resistor 1, and
As shown in the figure, when power supply starts at time to, the temperature of the iron base 4 is low and the resistance value of the thermistor 3 is large at the beginning, so the voltage V _P at the connection point P is V _P > V _S , V _P > V _S + ε. As a result, the third comparator 11 outputs an ON signal for the heating element, the heating element generates heat, and the iron base 4 is heated. At the same time, the output of the first comparator 9 becomes low level, and the first light emitting diode 15 turns on. Light.
Furthermore, the current flowing through the resistor 21 of the base bias circuit 24 flows into the output terminal of the first comparator 9 through the diode 25, so the terminal voltage of the Zener diode 22 of the base bias circuit 24 is low and the transistor 18 is in an off state. becomes. The low temperature condition is thus indicated by the first light emitting diode 15. Thereafter, at time t1, when the temperature of the iron base 4 falls within the appropriate temperature range, V _P <V _S +ε, the output of the first comparator 9 becomes high level, and the first light emitting diode 5 turns off. On the other hand, since V _P > V _S −ε in the appropriate temperature range, the second comparator 10
output remains high level. As a result, the terminal voltage of the Zener diode 22 becomes equal to or higher than the specified value, and the Zener diode 22 becomes conductive. As a result, resistor 21 and Zener diode 22
A base current flows to the base of the transistor 18 through the transistor 18, and the transistor 18 is turned on. This causes the third light emitting diode 20 to light up to indicate the appropriate temperature state. On the other hand, at time t2, when V _P <V _S , the output of the third comparator 11 becomes low level and the heating operation of the heating element is stopped. After that, the temperature of the iron base 4 decreases and when V _P > V _S , the third
The output of the comparator 11 becomes high level, and the heating element generates heat again. Thereafter, as shown in FIG. 2, the heating element is controlled to be turned on and off once the set temperature Th is reached, and the iron base 4 is maintained at a temperature within the appropriate temperature range of the set temperature.

Now, if at time t3, the temperature of the iron base 4 temporarily falls below the appropriate temperature range due to some load factor, the resistance value of the thermistor 3 increases, and temporarily V _P > V _S +ε becomes.
As a result, the first comparator 9, which determines whether or not the temperature of the iron base 4 is low, is about to operate.
However, since the first feedback resistor 12 with a small resistance is connected to both ends of the first comparator 9, the value of V _P −(V _S +ε) is extremely small as shown in FIG. In this case, the first comparator 9 is activated;
The output level never becomes low level. Therefore, since the transistor 18 is not turned off, the third light emitting diode 20, which indicates the appropriate temperature, is not turned off.

On the other hand, if the temperature of the iron base 4 temporarily exceeds the appropriate temperature range, the resistance value of the thermistor 3 decreases and temporarily becomes V _P <V _S -ε.
As a result, the second comparator 10 attempts to operate. In this case, since the resistance value of the second feedback resistor 13 of the second comparator 10 is large, it is activated immediately, the output of the comparator 10 becomes low level, the transistor 18 is turned off, and the second feedback resistor 13 that indicates the appropriate temperature is activated. The light emitting diode 20 of No. 3 is turned off. Therefore, as shown in Figure 2, there is a
A hysteresis region having a temperature range determined by the value of the feedback resistor 12 is set, and the appropriate temperature display will not be canceled only if the temperature of the iron base 4 falls to the hysteresis region.

Next, at time t4, when the temperature of the iron base 4 decreases significantly and falls below the above-mentioned hysteresis region, the first comparator 9 is activated and the output becomes low level. As a result, the transistor 18 is turned off and the third light emitting diode 20 is turned off.
On the other hand, when the output of the first comparator 9 becomes low level, the first light emitting diode 15 indicating low temperature is lit. Once the temperature of the iron base 4 falls below the hysteresis region, the temperature of the iron base 4 rises sufficiently and exceeds the upper limit of the hysteresis region at time t5, and the first light emitting diode 15 indicating the low temperature is turned off. , the third light emitting diode 20 indicating the appropriate temperature lights up.

With an iron configured in this way, even if a temporary load fluctuation occurs during ironing work and the temperature of the iron base 4 falls below the appropriate temperature range, the iron will still show that the above temperature is within the appropriate temperature range. The third light emitting diode 20 is never turned off. Furthermore, in the event of a significant temperature drop below the hysteresis region shown in Figure 2,
The third light emitting diode 20 is turned off, and the first light emitting diode 15 indicating low temperature is turned on.

Therefore, the iron user can continue the ironing work with peace of mind until the third light emitting diode 20 is turned off and the first light emitting diode 15 is turned on, and work efficiency can be improved.

Furthermore, in a normal state where no temporary load fluctuation occurs, the temperature of the iron base 4 is controlled within the appropriate temperature range shown in FIG. 2, so that the temperature control performance of the iron itself does not deteriorate.

In addition, in the above embodiment, a device that displays three types of temperatures, low temperature, high temperature, and suitable temperature, is described, but the present invention is not necessarily limited to this. It may be for display only. Even if this is done, there is no problem in use since the iron must not be used unless the appropriate temperature is displayed.

Further, in the above embodiments, a light emitting diode was used as the display, but it is needless to say that the present invention is not limited to this.

〔Effect of the invention〕

As explained above, according to the present invention, even if
To provide an iron that can maintain an appropriate temperature display even if the temperature of an iron base temporarily falls below the appropriate temperature range, and can improve the efficiency of ironing work.

[Brief explanation of drawings]

FIG. 1 is a temperature control circuit diagram of an iron according to an embodiment of the present invention, and FIG. 2 is an operation explanatory diagram of the temperature control circuit. 1... Variable resistor for temperature setting, 3... Thermistor (temperature sensitive resistance element), 4... Iron base, 5,
6, 7, 8...Resistor, 9...First comparator, 10
...Second comparator, 11...Third comparator, 12
...first feedback resistance, 13...second feedback resistance,
15...First light emitting diode, 17...Second light emitting diode, 18...Transistor, 20...
...Third light emitting diode (appropriate temperature indicator), 22...
...Zener diode.

Claims (1)

[Claims] 1 A DC power source, a temperature-sensitive resistance element that detects the temperature of the iron base heated by the heating element and changes the resistance value, and a temperature-setting variable connected to the power source via the temperature-sensitive resistance element. A reference voltage consisting of a resistor and a plurality of resistors, which is half of the above power supply voltage.
A voltage generation circuit that generates a voltage of ±ε of V _S and this reference voltage V _S , and a voltage from this voltage generation circuit.
A first comparator that compares V _S +ε with the divided voltage V _P of the above-mentioned temperature-sensitive resistance element and variable resistor, and outputs a low level when V _P > V _S +ε, and this first comparator. The voltage V _S -ε from the voltage generating circuit and the divided voltage V _P are compared with the first feedback resistor connected to both ends of the voltage generating circuit, and when V _P <V _S -ε, the output becomes a low level. a second feedback resistor connected to both ends of the second comparator and having a resistance value greater than the first feedback resistor, and a reference voltage V _S from the voltage generating circuit and a divided voltage. Compare V _P , V _P > V _S , V _P
A third comparator that outputs an on/off signal for the heating element based on ≦V _S , an appropriate temperature indicator connected to the power source via a transistor, a base bias circuit of the transistor, and this bias circuit. and a pair of diodes connected between the output terminals of the first and second comparators with their cathodes facing the output terminals.