JPS6028492B2 - Electric rice cooker control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for an electric rice cooker, and in particular, it is an object of the present invention to make all mechanical lever-type rice cooking switch sections available.

Conventionally, an electric rice cooker that detects the completion of cooking using a temperature sensor that utilizes the Curie point of ferrite has used a configuration as shown in FIG.

In FIG. 1, 1 is an outer pot, 2 is an inner pot, 3 is a main heater, and 4 is a temperature sensor that uses the Kiley point of ferrite, which loses its magnetic properties when the temperature reaches the end of cooking.
Therefore, when the cooking temperature is reached, the magnet 5 separates from the temperature sensor 4 and falls, thereby opening the electrical contacts 8 and 9 via the transmission shaft 6 and lever type lever 7.
Power supply to the main heater 3 is stopped. Reference numeral 10 denotes a push pin, which allows the electrical contacts 8 and 9 to be opened and closed independently of the temperature sensor 4.

In the case of such a conventional structure, since the rice-cooking switch part is locked, the structure is complicated and requires a large space at the bottom. Since it can be opened and closed, the electrical contacts 8 and 9 may be opened during rice cooking.

By the way, recently, microcomputers have been introduced into electric rice cookers, and power control has come to be performed by semiconductors, and the rice cooking switch section has also become electronic rather than mechanical, using semiconductor sensors and the like.

FIG. 2 shows the structure of a typical example thereof, and in FIG. 2, numerals 1 to 3 are the same parts as in FIG. 1. 11 is a temperature sensor, 12 is a rice cooking switch, 13 is an indicator lamp that indicates the operating status of the rice cooker, 14 is a sounding body, and rice cooking switch 12
When a touch switch or the like is used for cooking, this is used to express the operation with sound, and to notify the completion of shading after cooking.

15 is a control circuit section.

In the case of such a structure, the structure is simpler and the rice cooker can be made more compact than the structure shown in FIG. 1, but since a touch switch or a push button switch is used as the rice cooking switch 12, If the power is accidentally turned off during rice cooking, or when a power outage occurs and is restored, it is necessary to turn on the rice cooking switch 12 again.

In view of the current situation, the present inventor has developed a control circuit as shown in FIG. 3 in order to eliminate the trouble of turning on the rice cooking switch again when the power is accidentally turned off or a power outage occurs.

In FIG. 3, 16 is a main circuit section using a microcomputer etc., 17 is a rice cooking switch, and 18 is a main circuit section 16.
A speaker or a piezoelectric buzzer is used as a sounding body that emits sound in response to a signal from terminal a.

Reference numeral 19 denotes a light emitting diode as an indicator lamp to indicate that rice is being cooked; 20 is a light emitting diode as an indicator lamp to indicate that rice is being cooked; 21 is a light emitting diode as an indicator lamp to indicate that rice is being kept warm; and 22 is a light emitting diode as an indicator lamp to indicate that rice is being heated. terminal b
A semiconductor element 23 is a capacitor that controls the power of the main heater for rice cooking based on a signal from the capacitor 23, and a current limiting resistor 24 when the rice cooking switch 17 is turned on.
When the light emitting diode 20 is charged through the charge backflow prevention diode 25 and lights up after cooking, the current is charged through the diode 26 that prevents current from flowing back from the light emitting diode 20 to the capacitor 23, and the current limiting resistors 27 and 28. Discharge.

Further, one terminal of this capacitor 23 is connected to the terminal c of the main circuit section 16 via a high input impedance buffer 29, and at the terminal c of the main circuit section 16, a rice cooking switch is activated depending on the presence or absence of charge in the capacitor 23. 17 is detected. In addition, Mikawama light emitting diode 19,20
, 21 are connected in series (only the resistor connected to the light emitting diode 20 is shown), and 31 is a transistor for driving the light emitting diodes 19, 20, 21 (only the transistor connected to the light emitting diode 201 is shown). ), both of which are built into the main circuit section 16. 32 is a circuit driving power source.

FIG. 4 shows a signal flowchart of the main parts of the circuit of FIG. 3, and the operation of the circuit of FIG. 3 will be explained with reference to FIG.

First, when the rice cooking switch 17 is turned on, the sounding body 18 emits a "beep" notification sound during the period A, and the rice cooking switch 1
Displays that 7 has turned ON.

Subsequently, a silent pulse is generated during B, and the capacitor 23 is charged by this pulse, and the state that the rice cooking switch 17 is ON is memorized. At this time, electricity is started to be supplied to the main heater and the light emitting diode 19 for cooking rice is lit. Next, when the cooking temperature reaches the temperature, the temperature sensor activates and at the same time the rice cooking switch 1
The electric charge of the capacitor 23 that has stored the ON state of rice cooker switch 17 is discharged through the transistor 31, and the stored contents of the operating state of the rice cooking switch 17 are reset.

By the way, when there is a power outage during rice cooking, or when the power is accidentally turned off and then turned on again, the main circuit section 1
At step 6, an operation is performed to detect the presence or absence of charge in the capacitor 23.

At this time, since the capacitor 23 is connected to the terminal c of the main circuit section 16 via the high input impedance buffer 29, even if the power is cut off due to a power outage, the capacitor 23
Since the electric charge No. 3 is maintained as it is with only a discharge to the extent of self-discharge, a "HIGH" signal is input from the high input impedance buffer 29 to the terminal c of the main circuit section 16, and this Semiconductor element 2 by
2 works normally and rice continues to be cooked when the power is turned on again. Therefore, there is no need to turn on the rice cooking switch 17 again. However, in the case of such a control circuit, a special pulse is required for the drive signal of the sounding body 18, and the capacitor 23 self-discharges during rice cooking. The present invention has been made in view of the current situation, and the content of the present invention will be explained below with reference to the drawings of FIGS. 5 and 6. FIG. 5 shows a control circuit according to an embodiment of the present invention, in which 33 is a main circuit section using a microcomputer or the like, 34 is a rice cooking switch, 35 is an indicator lamp that displays the water absorption step of the rice cooking process, 36 is a display lamp that indicates that the rice is being cooked; 37 is a display lamp that indicates that the rice is being cooked; 38 is a display lamp that indicates the cooking process after the rice has been cooked;
Reference numeral 39 is an indicator lamp that similarly displays the steaming process after the rice is cooked, and 40' is an indicator lamp that also indicates the warming process after the rice is cooked, and these indicator lamps 35 to 4 use light emitting diodes. .

Among these display lamps 35 to 40, display lamps 35 to 40
Reference numeral 37 is for displaying the rice cooking status in the rice cooking process, and one end is connected to the main circuit section 33, and the other end is commonly connected. In addition, the display lamp 38
This is for displaying after the rice cooking is completed, and one end is connected to the main circuit section 33, and the other end is connected in common. 41 is a capacitor for storing the operating state of the rice cooking switch 34; one end of this capacitor 41 is grounded, and the end of the capacitor 41 is connected to the main circuit section 33 via a high input impedance buffer 42; It is connected via a resistor 43 and a diode 44 to a common connection portion of the indicator lamps 35 to 37.

45 is a resistor for limiting the current of the indicator lamps 35 to 37;
Reference numeral 46 denotes a transistor which becomes conductive when a current flows through the indicator lamps 38 to 40', and when this transistor 46 becomes conductive, the charges stored in the capacitor 41 are discharged through the resistor 47.

48 and 49 are bias resistors for this transistor 46.

FIG. 6 shows a signal flowchart of the main parts of the circuit of FIG. 5, and the operation of the circuit of FIG. 5 will be explained with reference to FIG.

First, when the rice cooking switch 34 is temporarily turned on, the main circuit section 33 of the rice cooker starts operating, and the indicator lamp 35 for indicating water absorption lights up.

At this time, a part of the current flowing through the indicator lamp 35 is charged to the capacitor 41 via the diode 44 and the resistor 43.
The operation of the rice cooking switch 34 is memorized. Next, when the water absorption process is completed, the process moves to the rice cooking process, and the display lamp 36 is turned on. Also at this time, a part of the current flowing through the display lamp 36 is charged into the capacitor 41 via the diode 44 and the resistor 43. When this rice cooking process is finished, the process moves to the shading process, and the display lamp 37 is turned on. Also at this time, a part of the current flowing through the display lamp 37 is charged into the capacitor 41 via the diode 44 and the resistor 43. here,
All of these indicator lamps 35 to 37 are for indicating that rice is being cooked, and depending on the situation, only one indicator lamp may be used.

When the rice cooking process is completed, the indicator lamp 38 for the cooking process is lit, and a part of the current flowing through the indicator lamp 38 at this time flows to the base of the transistor 46 and becomes conductive, so that the charge in the capacitor 41 is transferred to the resistor 47. , are discharged through transistor 46.

After that, the unevenness process and the heat retention process continue, and the transistor 4
The capacitor 41 is discharged until the capacitor 6 becomes cutoff.

Further, all of these indicator lamps 38 to 40 indicate the end of rice cooking, and only one indicator lamp may be used.

By the way, if there is a power outage during rice cooking, or if the power is accidentally turned off and then turned on again, the main circuit section 33 detects the presence or absence of charge in the capacitor 33, and from the time when the power is turned off, perform the following actions. At this time, since the capacitor 41 is connected to the main circuit section 33 via the buffer 42 with high input impedance, even if the current is cut off due to a power outage, the charge in the capacitor 41 will only be discharged to the extent of self-discharge. will be retained as is. Then, as described above, the output signal of the buffer 42 allows rice to be cooked again by re-energizing after a power outage, and there is no need to reset the switch 34. As described above, with the control circuit according to the present invention, even if the power is turned off due to a power outage or by mistake, the rice cooking state can be restored to normal without having to turn on the rice cooking switch once the power is turned on again. This method has the advantage that it does not require dry batteries or large-capacity capacitors compared to the method of adding a power failure backup circuit, and it is also easy to reset the memory state. Moreover, since there is no need for a special pulse generation circuit and the capacitor can be continuously charged during rice cooking, there is no need to worry about self-discharge and the memory time can be extended. This will be extremely effective in achieving full computerization.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of a conventional electric rice cooker, and FIG. 2 is a sectional view showing the main parts of the electric rice cooker targeted by the present invention.
Fig. 3 is a circuit diagram showing a control circuit for an electric rice cooker previously developed by the present inventor, Fig. 4 is a waveform diagram showing the operation of the main parts of the circuit, and Fig. 5 is an electric rice cooker control circuit according to an embodiment of the present invention. FIG. 6 is a circuit diagram showing the control circuit of the rice cooker. FIG. 6 is a waveform diagram showing the operation of the main parts of the circuit. 33... Main circuit section, 34... Rice cooking switch, 35, 36, 37, 38, 39, 40... Display lamp, 41... Capacitor. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. A plurality of display lamps for displaying the rice cooking process are provided, divided into one for displaying rice cooking and one for displaying additional cooking after rice cooking, keeping warm, etc., and the display lamps for displaying rice cooking are activated by operation of a rice cooking switch. 1. A control circuit for an electric rice cooker, characterized in that the capacitor is charged by a current flowing through the lamp, and the capacitor is discharged by a current flowing through a display lamp for indicating when rice cooking is completed.