JPH01223518A - Electric cooker - Google Patents

Abstract

PURPOSE:To control the time of power supply to a heater in accordance with the cooking temperature of materials to be cooked by changing the resistance value of a negative or positive characteristic resistor sensitive to heat and changing the wavelength and the waveform of the output voltage of a square wave oscillating circuit in accordance with this change. CONSTITUTION:When the cooking temperature sensed by a negative characteristic resistor 14 (or a positive characteristic resistor) gradually rises, the resistance of the resistor 14 (or the positive characteristic resistor) is reduced (or increased) to raise the voltage applied to a non-inverted input terminal +. Since the charging voltage of a capacitor 12 reaches the applied voltage to the non-inverted input terminal +, by which the output voltage of a comparator 11 is turned off, in a long time, the time when the output of the comparator 11 is kept in the high level is extended. Thus, the time when the output of the comparator 11 is kept in the high level is varied to control the time of power supply to the heater in accordance with the cooking temperature of materials to be cooked.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF THE INVENTION The present invention relates to an electric cooking appliance that controls energization to a heater by using a switching element and a single energization control switch.

Conventional technology Conventionally, a bimetal is mainly used to control the energization of a heater used as a heat source for an electric cooking device such as a rice cooker, and the ON/OFF control of this bimetal turns the energization of the heater on and off. It is controlled to be OFF.

Problem to be Solved by the Invention However, when controlling the energization of the heater by controlling ON/OFF of the bimetal, it is difficult to control the ON/OFF of the bimetal.
, each control time spent on OFF control is long.

Therefore, since the cooking temperature of the food to be cooked generally tends to rise, there has been a problem that the cooking temperature of the food to be cooked cannot be controlled at the current conduction rate even if the temperature is low to some extent.

Means for Solving the Problems The present invention has been made to solve the above problems, and involves connecting a series circuit of a heater and an energization control switch to a commercial power source, and connecting a switching element in parallel to the energization control switch. A heat-sensitive negative characteristic resistor and a resistor (or a resistor and a heat-sensitive resistor that senses the cooking temperature of the food to be cooked) are connected to the commercial power supply and are connected to the commercial power supply through a voltage drop means to sense the cooking temperature of the food to be cooked. A rectangular wave oscillation circuit consisting of a comparator whose wavelength and waveform change depending on the resistance change of the surface heat sensitive resistor is connected. A power switch that closes when the energization control switch is open is connected between the connection point with the heater and the voltage drop means, and further connected in series with the non-inverting input terminal of the comparator. The connection points of the heat-sensitive negative characteristic resistor and the resistor, or the resistor and the heat-sensitive positive characteristic resistor are connected, and the square wave is output when the energization control switch is open. The output of the oscillation circuit is input to gate signal output means for outputting a gate signal to the switching element.

By doing this, the resistance value of each heat-sensitive resistor changes in accordance with the change in the cooking temperature of the food to be cooked, and moreover, the resistance value of each heat-sensitive resistor changes. Following this, the wavelength and waveform of the voltage output from the rectangular wave oscillation circuit change.

Therefore, following the application time of the voltage applied to the non-inverting input terminal of the comparator, the application time of the voltage applied to the inverting input terminal of the comparator also changes, and the output of the comparator changes to "Hpt".
The time for holding the level is varied to control the time for energizing the heater according to the cooking temperature of the food to be cooked.

Example An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1 showing the circuit configuration of the embodiment, S is a commercial power source, to which a series circuit consisting of a heater 1 and an energization control switch 2 made of bimetal or the like is connected, and the energization control switch 2 is made of a thyristor. Switching elements (hereinafter referred to as thyristors) 3 are connected in parallel.

Reference numeral 45 denotes a voltage drop means consisting of a rectifier diode 4 and a dropper resistor 5, and a series circuit of a transistor 9 and resistors 10a and 10b is connected to the commercial power supply S through this voltage drop means 45. Furthermore, the connection point between both resistors 10a and 10b is connected to the gate of the thyristor 3.

Further, a constant voltage circuit 7 is connected to the commercial power supply S via a voltage drop means 45, and a heat sensitive negative characteristic resistor 14 whose resistance decreases as the temperature increases and a resistor 17 are connected in series to the constant voltage circuit 7. Circuits are connected in parallel. In addition, the connection point between the negative characteristic resistor 14 and the resistor 17 is connected to the non-inverting input terminal of the comparator 11, and a resistor (positive feedback Resistor) 15 is connected. A capacitor 12 is connected between the inverting input terminal e of the comparator 11 and the free end side (ground side) of the resistor 17, and is connected between the inverting input terminal e and the output of the comparator 11. A resistor (negative feedback resistor) 16 is connected between the two ends. Moreover, these resistors 17 and negative characteristic resistor 1
4. Rectangular wave oscillation circuit 18 with comparator 11, resistor (positive feedback resistor) 15, resistor (negative feedback resistor) 16, and capacitor 12
It consists of Reference numeral 6 denotes gate signal output means for transmitting a gate signal to the thyristor 3, and when the output signal from the rectangular wave oscillation circuit 18 (comparator 11) is input, the gate signal output means 6 transmits a gate signal to the transistor 9. It functions to conduct current. A power switch 8 is connected between the voltage drop means 45 and the connection point between the commercial power supply S and the heater 1, and the power switch 8 is closed when the energization control switch 2 is open. It is something to do.

Further, FIG. 7 is a circuit diagram when a series circuit of a resistor and a heat-sensitive positive characteristic resistor for sensing the cooking temperature of the food is connected to the commercial power supply S via a voltage drop means 45. In the figure, the parts given the same numbers as in FIG. 1 are common parts, so the explanation will be omitted.

In the figure, 41 and 71 are a heat-sensitive positive characteristic resistor and a resistor whose resistance increases as the temperature rises, respectively. It is connected in parallel to the commercial power supply S via the power source S.

In such a configuration, if the power switch 8 is left open when applying current to the heater 1, when the commercial power source S is applied, the heater 1 starts being energized via the energization control switch 2.

After a certain period of time has elapsed, when the temperature sensed by the energization control switch 2 reaches the operating temperature of the energization control switch 2, the energization control switch 2 is opened, and after a certain period of time has elapsed since the energization control switch 2 has been opened, When the temperature sensed by the energization control switch 2 reaches the return temperature of the energization control switch 2, the energization control switch 2 closes. This state is repeated to control the energization rate to the heater 1 according to the operating temperature characteristics of the energization control switch 2 by 0N10FF.

Next, when the power switch 8 is closed while the energization control switch 2 is in the open state, the commercial power supply S is applied to the constant voltage circuit 7 via the voltage drop means 45, and the constant voltage circuit 7 is The voltage used as the power source is applied to the rectangular wave oscillation circuit 18.

Therefore, the reference voltage (input voltage to the non-inverting side input terminal) of the resistor 15.17 in the square wave oscillation circuit 18 and the negative characteristic resistor 14 is also the same as that of the capacitor 12 in the square wave oscillation circuit 18. When the voltage is higher than the input voltage applied to the inverting input terminal e by the resistor 16, the output signal (a rectangular wave as shown in FIG. 3) from the rectangular wave oscillation circuit 18 (comparator 11) is output to the gate signal output means 6. do.

At this time, the voltage applied to the non-inverting side input terminal varies depending on the cooking temperature sensed by the negative characteristic resistor 14 (or the positive characteristic resistor 41), and the - side, the voltage applied to the inverting side input terminal The voltage applied to terminal e has the wavelength and waveform as shown in Figure 5, and when the voltage applied to the inverting input terminal e reaches the voltage applied to the non-inverting input terminal, it becomes a rectangular wave. The output signal from the oscillation circuit 18 (comparator 11) becomes 'L' level, and the gate signal output means 6 outputs a trigger pulse as shown in FIG. Pass current.

Therefore, through the transistor 9, both the resistors 10a,
A voltage generated in the resistor 10a by the current flowing through the resistor 10b is applied to the gate of the thyristor 3, and a current is passed through the thyristor 3 to the heater 1 according to the energization rate to the transistor 9 related to the wavelength and waveform. .

Furthermore, as the cooking temperature sensed by the negative characteristic resistor 14 (or the positive characteristic resistor 41) gradually increases, the resistance of the negative characteristic resistor 14 (or the positive characteristic resistor 41) decreases (or increases), and the above-mentioned resistance increases. The voltage applied to the non-inverting input terminal becomes higher.

At this time, the charging voltage of the capacitor 12 (the voltage applied to the inverting input terminal e) takes a long time to reach the voltage applied to the non-inverting input terminal at which the output voltage of the comparator 11 is turned off. The time period during which the output of the device 11 remains “H” is the sixth
As shown in the figure, the current flow to the heater 1 is controlled so that the current flow rate becomes longer and the current flow rate to the transistor 9 decreases.

Conversely, when the cooking temperature of the food detected by the negative characteristic resistor 14 (or the positive characteristic resistor 41) is low, the energization to the heater 1 is controlled so that the energization rate to the transistor 9 increases, contrary to the above. .

Effects of the Invention As described above, according to the present invention, a series circuit of a heater and an energization control switch is connected to a commercial power source, a switching element is connected in parallel to the energization control switch, and a voltage drop means is connected to the commercial power source. A series circuit of a heat-sensitive negative characteristic resistor and a resistor (or a resistor and a heat-sensitive positive characteristic resistor that senses the cooking temperature of the thing to be cooked) is constructed. At the same time, a rectangular wave oscillation circuit consisting of a comparator, etc., whose wavelength and waveform change depending on the resistance change of a heat-sensitive resistor, is connected.
A power switch that closes when the energization control switch is open is connected between the connection point between the commercial power source and the heater and the voltage drop means, and a power switch that closes the circuit when the energization control switch is open is connected to the non-inverting input terminal of the comparator. , connect the connection points of the heat-sensitive negative characteristic resistor and the resistor, or the resistor and the heat-sensitive positive characteristic resistor connected in series with each other, and output when the energization control switch is open. By inputting the output of the rectangular wave oscillation circuit to the gate signal output means for outputting a gate signal to the switching element, each of the above-mentioned signals can be adjusted in accordance with changes in the cooking temperature of the food to be cooked. The resistance value of the heat-sensitive resistor changes, and the wavelength and waveform of the voltage output from the rectangular wave oscillation circuit change in accordance with the change in the resistance value of each heat-sensitive resistor. Following the application time of the voltage applied to the non-inverting input terminal of the comparator, the application time of the voltage applied to the inverting input terminal of the comparator also changes, and the output of the comparator maintains the ``H'' level. To provide an electric cooker that controls the time for energizing the heater according to the cooking temperature of the food by varying the time for which the food is heated, and that controls the cooking temperature of the food even at a certain low temperature during cooking. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an electric cooking device according to an embodiment of the present invention, and FIGS. 2, 3, and 4 respectively show the state of energization to the heater via the thyristor, the output state of the comparator, and It is a time chart showing the output state of the gate signal input to the switching element, and FIGS. 5 and 6 show the input voltage to the comparator and the comparator when the cooking temperature of the same food is slightly low and high. It is a diagram showing the state with the output voltage from
FIG. 7 is a circuit diagram according to the second claim of the same patent. 1...Heater, 2...Electrification control switch,
3... Switching element (thyristor), 45...
Voltage drop means, 6... Gate signal output means, 14...
- Heat sensitive negative characteristic resistor, 41... Heat sensitive positive characteristic resistor, 17.71... Resistor, 18... Square wave oscillation circuit, S... Commercial power supply.

Claims (2)

[Claims] (1), connect the series circuit of the heater (1) and the energization control switch (2) to the commercial power supply (S), connect the switching element (3) to the energization control switch (2) in parallel, and connect the commercial power supply A series circuit of a heat-sensitive negative characteristic resistor (14) and a resistor (17) is connected to (S) via a voltage drop means (45), and a series circuit of a heat-sensitive negative characteristic resistor (14) and a resistor (17) is connected to A rectangular wave oscillation circuit (18) consisting of a comparator (11) whose wavelength and waveform change depending on the resistance change of the negative characteristic resistor (14) is connected. A power switch (8) that closes when the energization control switch (2) is open is connected between the connection point and the voltage drop means (45), and further, a power switch (8) that closes when the energization control switch (2) is open is connected. Connect the connection point between the heat-sensitive negative characteristic resistor (14) and the resistor (17) to the inverting side input terminal (■),
and gate signal output means (6) for outputting the output of the rectangular wave oscillation circuit (18), which is output when the power switch (8) is closed, as a gate signal to the switching element (3). An electric cooker characterized by inputting. (2) A series circuit of a resistor (71) and a heat-sensitive positive characteristic resistor (41) for sensing the cooking temperature of the food is connected to the commercial power supply (S) via a voltage drop means (45). The electric cooking device according to claim 1, characterized in that the electric cooking device is connected.