JP2009285207A - Rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rice cooker surely giving an alarm for a predetermined time period even if a back-up battery capacity runs out. <P>SOLUTION: The rice cooker includes a first back-up circuit 27 for backing up a power source of a microcomputer 19 with the battery 24, and a second back-up circuit 35 for charging a capacitor 31 with an AC power source, and backing up the power source of the microcomputer 19 with the capacitor 31. When the capacity of the battery 24 runs out, the power source of the microcomputer 19 is backed up by the second back-up circuit 35 for a predetermined time period to display the alarm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rice cooker provided with backup means.

Conventionally, there has been a rice cooker equipped with a battery as backup means for supplying power (see, for example, Patent Document 1).
JP 2008-48955 A

  In a conventional rice cooker equipped with a backup means, it is possible to warn while a predetermined part can be backed up with a battery. However, in the case of a predetermined pressure during cooking, a warning cannot be issued if the battery capacity is exhausted. As a result, for example, when the lid of the rice cooker is opened in a state of a predetermined pressure, there is a problem that the steam may spout out and the user may be burned.

  This invention is made | formed in view of said situation, Even if it is a case where the capacity | capacitance of a backup battery runs out, it aims at providing the rice cooker which can perform a warning for a fixed time reliably. .

  According to the first aspect of the present invention, there is provided a first backup unit that backs up a power source of a predetermined part with a battery, and a second unit that charges a charging body when there is an AC power source and backs up the power source of the predetermined part with the charging body. When the battery capacity is exhausted, the second backup unit backs up the power of the predetermined part for a certain period of time and issues a warning.

  Invention of Claim 2 is a rice cooker of Claim 1, Comprising: During the pressurization process in a cooking process, a warning is performed for a fixed time, It is characterized by the above-mentioned.

  According to the rice cooker of this invention, even if it is a case where the capacity | capacitance of a backup battery runs out, the power supply of a predetermined component can be reliably backed up with the charging body charged with AC power supply. Therefore, even when pressure is applied during the cooking process, a warning is given to notify the pressurized state, and the user can be prevented from opening the lid of the rice cooker carelessly. Therefore, the rice cooker lid is opened in a state where pressure is applied, and there is no risk that the steam will blow out vigorously and the user may be burned, and a highly safe rice cooker can be realized.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of an electric rice cooker 1 that is an embodiment of the present invention. On the front surface or upper surface of the electric rice cooker 1 or on the front surface and the upper surface, a display device 2 such as an LED or an LCD for displaying a clock display or a rice cooking state of the electric rice cooker is provided. In addition to the rice cooking start / cancel buttons 3, 4, various input means 5 such as a rice cooking menu selection button and a rice cooking start reservation time setting operation are disposed around the display 2. .

  In this rice cooker 1, in order to perform rice cooking excellent in taste and texture, the pressure in the rice cooking container is adjusted in the rice cooking process which is a cooking process. Therefore, in order to prevent the lid from being opened during the pressurization stroke, a pressure state display 6 is displayed during the pressurization stroke, and a warning is also displayed by voice when an attempt is made to open the lid due to an erroneous operation or the like. However, the precious pressure state display 6 and the warning display do not function when the power source of the microcomputer circuit as the control means is lost.

  FIG. 2 is a circuit diagram of the electric rice cooker 1 of the present invention. In FIG. 2, 11 is a commercial AC power source, for example, a power source of AC 100V. Reference numeral 12 denotes a rectifier circuit, which is specifically configured by bridge-connecting diodes. An RC low-pass filter 15 including a resistor 13 and a capacitor 14 is connected to the output-side positive terminal of the rectifier circuit 12. A switching power supply circuit 16, which is a well-known technique, is connected to a connection point between the resistor 13 and the capacitor 14 of the RC low-pass filter 15, and DC 20 V is output from the switching power supply circuit 16. Here, the reason why the output voltage is DC 20 V is to efficiently drive a fan (not shown) as a cooling means. Further, the other end of the capacitor 14 is connected to the output-side negative terminal of the rectifier circuit 12 to constitute a common terminal 17.

  The output of the switching power supply circuit 16 is supplied to both the load circuit 18 and the microcomputer circuit 19 which is a predetermined component. The load circuit 18 is for performing rice cooking heating, which is an essential function of the rice cooker 1, and specifically comprises an electromagnetic induction heating circuit including a resonance circuit. On the other hand, the microcomputer circuit 19 is specifically composed of a control circuit including a CPU, a status indicator and the like.

  A voltage of DC 20 V is stepped down to 5 V and applied to the microcomputer circuit 19 by a three-terminal element 21 which is a general-purpose regulator. Specifically, the three-terminal element includes an NPN transistor 21, a bias resistor 22, and a Zener diode 23. Further, a series circuit of the primary battery 24, the limiting resistor 25, and the diode 26 is connected in parallel with the microcomputer circuit 19 to constitute a first backup circuit 27 serving as a first backup means. The negative side of the primary battery 24 is connected to the common terminal 17, and the positive side of the primary battery 24 is connected to the anode of the diode 26 via the limiting resistor 25. The cathode side of the diode 26 is connected to the positive side of the microcomputer circuit 19.

  A voltage of DC 20 V is stepped down to 5 V and applied to the load circuit 18 by a three-terminal element 28 which is a general-purpose regulator. A series circuit including the switching element 29, the limiting resistor 30, and the capacitor 31 is connected in parallel with the load circuit 18. Specifically, the switching element 29 is composed of an NPN transistor, and the collector of the transistor 29 is connected to the positive side of the load circuit 18. Further, a limiting resistor 30 and a capacitor 31 are connected in series to the emitter of the transistor 29, and one terminal of the capacitor 31 is connected to the common terminal 17. Here, an electrolytic capacitor capable of obtaining a large capacitance at a relatively low cost is used as the capacitor 31 as a charging body. A series circuit of a bias resistor 32 and a Zener diode 33 is connected to the positive side of the load circuit 18, and the cathode side of the Zener diode 33 is connected to the bias resistor 32 and the anode side is connected to the common terminal 17. The base of the NPN transistor 29 is connected to the connection point between the bias resistor 32 and the Zener diode 33. The anode of the diode 34 is connected to the emitter of the NPN transistor 29, and the cathode of the diode 34 is connected to the positive side of the microcomputer circuit 19. The second backup circuit 35 as the second backup means is configured by the NPN transistor 29, the limiting resistor 30, the capacitor 31, the bias resistor 32, the Zener diode 33, and the diode 34 as described above.

  Next, the operation of the present embodiment having the above configuration will be described. The DC voltage smoothed by the rectifying and smoothing circuits 12 and 15 is converted to DC 20 V by the switching power supply circuit 16 and applied to the load circuit 18 and the microcomputer circuit 19. When the rice cooker 1 is operated to start operation, a voltage stepped down to 5 V DC by the regulator 28 is applied to the load circuit 18. The power supply to the load circuit 18 is turned off by a control signal when a series of rice cooking steps is completed. Also, when the AC power supply is lost due to a power failure or the like, the power supply to the load circuit 18 is cut off. By the way, in the present embodiment, a series circuit including the transistor 29, the limiting resistor 30, and the capacitor 31 is connected in parallel with the load circuit 18. The base potential of the transistor 29 is given by the bias resistor 32 and the Zener diode 33, and the transistor 29 is turned on when AC power is present. Therefore, a current flows from the collector to the emitter of the transistor 29, and the capacitor 31 is always charged. The electric charge charged in the capacitor 31 is held without being discharged unless the diode 34 becomes conductive.

  The power supply to the microcomputer circuit 19 is supplied from the AC power supply via the switching power supply circuit 16 when the AC power supply is supplied at a normal voltage level. However, if the AC power supply is lost due to a power failure or the like, the voltage drops extremely and the supply voltage to the microcomputer circuit 19 cannot be maintained at 5V, and if it drops to about 3.5V, the primary battery 24 to the limiting resistor 25 and the diode Power is supplied to the microcomputer circuit 19 via 26. Here, the microcomputer circuit 19 operates if there is a voltage of at least 3V. Thus, since the voltage of the primary battery 24 is lower than 5 V supplied from the AC power supply, as long as the AC power supply exists, the power to the microcomputer circuit 19 is supplied from the AC power supply side and is not supplied from the battery side. . Therefore, if the battery capacity has a certain size, the battery voltage is normally maintained for a period of about 4 to 5 years, depending on the frequency of power failure.

  Even with the backup of only the primary battery 24 as described above, it is possible to ensure the power supply of the microcomputer circuit 19 for a period of about 4 to 5 years. Unless it is replaced, the power source of the microcomputer circuit 19 cannot be secured. Therefore, in such a state, even if a high pressure is applied to the inner container of the rice cooker 1, no warning is displayed, and if the user accidentally opens the lid of the rice cooker 1, high-temperature steam is ejected and burns. There was a risk of incurring.

  However, according to this embodiment, even when the discharge of the primary battery 24 proceeds and the voltage of 3V cannot be maintained, the charge charged in the capacitor 31 is supplied to the microcomputer circuit 19 via the diode 34. Will be. By this, although it is a fixed period until the pressure of the inner container of the rice cooker 1 is reduced, the power source of the microcomputer circuit 19 is backed up and a warning display such as flickering the pressure state display 6 can be performed. Therefore, it can avoid that a user opens the lid | cover of the rice cooker 1 by misoperation, and a rice cooker with high safety | security can be implement | achieved at the time of a power failure. The voltage when the capacitor is fully charged is set to a value slightly lower than the initial voltage of the primary battery.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to these Examples. For example, in the above embodiment, the case where an electrolytic capacitor is used as the capacitor 31 has been described, but it goes without saying that the capacitor 31 may be of other types. In this embodiment, the microcomputer circuit 19 and the load circuit 18 are configured as separate circuits to suppress the capacitance of the capacitor 31, but the microcomputer circuit 19 and the load circuit 18 are separated from each other using a large-capacity capacitor. It may be a configuration that does not.

It is an external view of the electric rice cooker which is an Example of this invention. It is a circuit diagram of an electric rice cooker same as the above.

Explanation of symbols

1 Rice cooker (electric rice cooker)
27 First backup circuit (first backup means)
35 Second backup circuit (second backup means)
31 Capacitor (Charging body)
19 Microcomputer (specified parts)
24 batteries (primary batteries)

Claims (2)

A first backup means for backing up the power of a predetermined part with a battery, and a second backup means for charging a charging body when there is an AC power source and backing up the power of the predetermined part with the charging body,
When the capacity of the battery is exhausted, the second backup means backs up the power of the predetermined part for a certain period of time, and gives a warning. The rice cooker according to claim 1, wherein a warning is given for a predetermined time during the pressurizing / depressurizing process in the cooking process.

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