JPH03212223A - Electric rice cooker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electric rice cooker in which a heater is controlled by a microcomputer through a series of contacts.

A. Prior Art In recent years, electric rice cookers for home use have been manufactured that use microcomputers to control the heat level and operate on timers.

Conventionally, this type of electric rice cooker has generally had a configuration as shown in FIGS. 3 and 4. The configuration will be explained below.

In FIG. 3, an outer lid 1 is attached to a main body 2 so as to be openable and closable, and a heater 3 is attached to the lower part of the main body 2 as a heat source for cooking rice. An inner pot 4 is placed on the heater 3. The temperature sensor unit 6 is biased upward by a spring, has a negative characteristic thermistor built into it, and is attached so as to be in contact with the bottom surface of the inner pot 4 when the inner pot 4 is placed on the pleats 3. ing. The connecting rod 6 is fixed to the temperature sensor unit 5. The operating lever 7 turns the connecting rod 6 up and down to turn on and off a switch 8.

With the above configuration, when the inner pot 4 is taken out of the main body 2, the temperature sensor unit 5 is moved upward by the spring 3...-/, the operating lever 7 is pushed up by the connecting rod 6, and the switch 8 is pressed. The state in which there is no rice pot is generated as an off signal of the switch 8.

FIG. 4 is a circuit diagram of this electric rice cooker, in which a switch 8 that operates depending on the presence or absence of the inner pot 4 is connected to a microcomputer 9 that has programs for rice cooking operation, timer operation, etc. The heater 3 is energized by the relay contact 10 during the rice cooking operation. The heater 11 is provided on the side of the main body 2, and is energized during the heat retention operation. The drive circuit 12 drives the bidirectional three-terminal control element 13 with the output of the microcomputer 9, and the relay drive circuit 14 opens and closes the relay contacts 10 with the output of the microcomputer 9. The LCD 15 is for operation display;
The input switch 16 is used by the user to input information to the operating microcomputer 9. The temperature sensor 17 detects the temperature of the inner pot 4 and inputs it to the microcomputer 9.

When the inner pot 4 is properly set and the input switch 16 is operated to start the heating operation, the heating heater 3
Since the temperature of the heater 3 will rise rapidly, causing melting of the heater 3 and failure of parts, an off signal from the switch 8 is given to the microcomputer 9 so that the heater 3 is not energized unless the inner pot 4 is set. The configuration is such that energizing is prohibited.

Problems to be Solved by the Invention In such a conventional electric rice cooker, the relay contact 1o and the heating heater 3 are connected to both ends of the power supply, so if the microcomputer 9 is accidentally activated due to noise etc. Relay contact 10 when relay drive circuit 14 fails
When the inner pot 4 is closed, the heater 3 is not energized even though the inner pot 4 is not present, resulting in melting of the heater 3 and failure of parts.

The present invention is intended to solve the above-mentioned conventional problems, and it is possible to reliably turn off the relay contact when there is no inner pot, and to prevent the relay contact from turning on even if there is a malfunction due to noise or a failure of the relay drive circuit. This is the first purpose. A second purpose is to input the state of a switch that is turned off when there is no inner pot into the microcombi 6 page user to display the presence or absence of an inner pot.

Means for Solving the Problems In order to achieve the first object, the present invention provides a relay contact connected to a heater provided at the bottom of the main body, a microcomputer for controlling the relay, a relay power supply circuit, and the relay. The first problem-solving means is that the device is equipped with a switch connected to a power circuit and operated by a removable inner pot, and when there is no inner pot, the relay power circuit is turned off and a relay contact is opened. .

In addition to the first problem solving means, the present invention also includes a voltage detector for detecting the voltage of the relay power supply circuit, and the output of the voltage detector is input to a microcomputer, and the voltage of the relay power supply circuit is used to determine the state of the switch. The second problem-solving means is to input the information into the microcomputer.

Effect of the present invention is based on the first problem solving means described above, and when the inner pot is removed, the voltage of the relay power supply becomes zero, making it impossible to drive the relay, and without the inner pot. The relay contact can be reliably held in the OFF state at certain times. Further, according to the second problem-solving means, the status of the switch can be input to the microcomputer and the presence or absence of the inner pot can be displayed on the LCD or the like.

EXAMPLE Hereinafter, an example of the first invention will be described based on FIG. Note that components having the same configuration as those of the conventional example are given the same reference numerals, and description thereof will be omitted.

In FIG. 1, a microcomputer 18 has programs for rice cooking operations and timer operations.

The switch 19 operates depending on the presence or absence of the inner pot, and is connected to the relay power supply circuit 20. This relay power supply circuit 2o is composed of a diode and a capacitor, and generates relay power. The relay drive circuit 21 includes a relay coil 22 and a transistor 23 that drives the relay coil 22.
It consists of The diode 24 and the capacitor 25 constitute a power supply circuit for the microcomputer 18.

To explain the operation in the above configuration, when the inner pot is closed, the switch 19 is off, so the output voltage of the relay power supply circuit 2o becomes zero. Therefore, since the relay coil 22 cannot be driven, the relay contact 10 is ensured to be in the OFF state when there is no pot.

When the inner pot is set in the main body, the switch 19 is closed and a voltage is generated in the relay power supply circuit 2o.

When the input switch 16 is operated to perform the rice cooking operation, the transistor 23 is turned on, the relay coil 22 is driven, and the relay contact 10 is closed, so that the heater 3 is energized.

As described above, according to the electric rice cooker of the embodiment of the first invention,
If there is no inner pot, switch 19 turns on the power supply circuit 2o.
Since the output voltage of the relay is set to zero, the relay contact 10 can be turned off reliably, and the relay contact 1o can be prevented from being turned on even in the event of a malfunction due to noise or a failure of the relay drive circuit 21.

Next, a second embodiment of the invention will be described based on FIG. 2. Components having the same configuration as the embodiment of the first invention are given the same reference numerals, and the explanation thereof will be omitted.

In FIG. 2, the microcomputer 26 also receives the output of the voltage detector 27. A voltage detector 27 detects the voltage of the relay power supply circuit 20.

The LCD 28 can also display the status of the switch 19.

To explain the operation in the above configuration, when there is no inner pot, the switch 19 is in the OFF state, and the relay power supply circuit 2
Since no voltage is generated at o, it is not possible to drive relay coil (v22), and when there is no inner pot, relay contact 1o
can be guaranteed to be in the off state. Also,
The output of the voltage detector 27 causes the microcomputer 2 to
Since the state of the switch 19 is input to the microcomputer 6, the microcomputer 26 can also detect the state of the switch 19. When the inner pot is set, the switch 19 is closed, so a voltage is generated in the relay power supply circuit 2o, and the relay coil/v22 can be driven.

Therefore, the rice cooking operation can be performed by operating the input switch 16. In addition, by detecting the voltage of the relay power supply circuit 20 with the voltage detector 27 and inputting it to the My9Bage computer 26, the voltage of the LCD 2
In step 8, "with pot" and "without pot" can be displayed at the same time.

As described above, according to the electric rice cooker of the embodiment of the second invention,
If there is no inner pot, switch 19 turns on the power supply circuit 2o.
The relay contact 10 can be surely turned off by setting the output voltage to zero, and the status of the switch 19 can be input to the microcomputer 26 by the voltage detector 2, and the presence or absence of the inner pot can be displayed on the LCD 28, improving usability. can.

Effects of the Invention As is clear from the embodiments described above, according to the present invention, the relay contact can be reliably turned off when there is no inner pot, and malfunctions caused by noise or short-circuit failures of the transistor for driving the relay can be prevented. It is possible to prevent the heater from melting by turning on the relay and energizing the heater. In addition, the presence or absence of the inner pot can be displayed by detecting the state of the switch that operates on the inner pot using a voltage detector and inputting it into the microcomputer, improving usability by 10 points.
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[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an electric rice cooker according to an embodiment of the present invention;
The figure is a circuit diagram of an electric rice cooker according to another embodiment of the present invention, FIG. 3 is a partial front view of a conventional electric rice cooker, and FIG. 4 is a circuit diagram of the same electric rice cooker. 1o... L'-m point, 11...
Heater, 18...Microcomputer, 19
・・・・・・Switch, 2゜・・・Relay power supply circuit.

Claims (2)

[Claims] (1) Equipped with a relay contact connected to a heater provided at the bottom of the main body, a microcomputer that controls the relay, a relay power supply circuit, and a switch connected to the relay power supply circuit and operated by a detachable inner pot. An electric rice cooker that turns off the relay power circuit and opens a relay contact when there is no pot. (2) A claim comprising a voltage detector that detects the voltage of a relay power supply circuit, the output of the voltage detector being input to a microcomputer, and the state of the switch being input to the microcomputer based on the voltage of the relay power supply circuit. Item 1
Electric rice cooker as described.