JPH0549535A - Microwave jar rice cooker - Google Patents

Abstract

PURPOSE:To provide the title rice cooker to boil tasty rice without being affected by supply voltage fluctuation during operation. CONSTITUTION:Supply voltage of a rice cooking heater 19 is directly or indirectly detected by a supply voltage detecting circuit 21. Detected data is read by a rice cooking heater control circuit 16 at given intervals, and a heating degree for the rice cooking heater 19 is controlled corresponding to the read value variation. Also, when the read value exceeds a previously set supremum value or infimum value, the read value is fixed at the supremum value or infimum by the rice cooking heater control circuit 16, and the heating degree for the rice cooking heater 19 is controlled based on this value. Thus, an ideal rice cooking condition unaffected by supply voltage fluctuation during operation can be obtained, and even if wrong read should be done by any cause, an abnormal rice cooking condition can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic jar rice cooker, and more particularly to a rice cooker heater control means for deliciously cooking rice.

[0002]

2. Description of the Related Art FIG. 1 is a rice cooker heater control circuit diagram in an example of a conventional electronic jar rice cooker. In FIG. 1, the transformer 1 depressurizes the alternating current supplied from the power supply circuit to its primary side terminal. The decompressed AC is rectified by the diode bridge 2 and smoothed by the electrolytic capacitor 3,
Noise is removed by the capacitor 4 to form a DC power supply. This DC power supply consists of Zener diode 9, resistor 7,
The microcomputer 16 by the transistor 8 and the diode 10
It becomes the power supply V _DD for driving. The driving power supply V _DD is supplied to the microcomputer 16 as a stable power supply by the electrolytic capacitor 11. Further, the DC power supply is branched from the anode side of the diode 10 via the diode 20 and constitutes another power supply V _L stabilized by the electrolytic capacitor 12. The separate power supply V _L supplies a high level signal to the digital transistor 17 for driving the rice cooking relay. The base of the digital transistor 17 is the output port P of the microcomputer 16.
It is connected to O1, and its collector is connected to the rice cooking relay 18. When the output port PO1 of the microcomputer 16 outputs a low level signal, the digital transistor 17 is turned on and the rice cooking relay 18 is also turned on. Also, resistors 5, 6, 14 and diode 13
The capacitor 15 and the capacitor 15 form a power supply voltage detection circuit 21. Since the DC power supply reflects the fluctuation of the power supply voltage on the primary side of the transformer 1, this DC voltage is applied to the resistor 5,
The voltage is divided by 6 and the voltage is input port PI1 of the microcomputer 16.
To enter. The diode 13 is for preventing a voltage much lower than the GND level of the microcomputer 16 from being input when the resistor 6 is short-circuited, and the resistor 14 and the capacitor 15 are for noise elimination. The steps of cooking rice include preheating, quantity confirmation (recognizing the amount of rice), rice cooking, spotty and heat retention. In the conventional example, the microcomputer 16 detects the power supply voltage from the input value to the input port PI1 at the end of the quantity acceptance section, and the microcomputer 16 detects the result of the power supply time ratio during one cycle of turning on and off the rice heating heater (so-called duty. There is a method in which rice is cooked based on this duty ratio. In this example, the microcomputer 1
6 turns on / off the rice cooking heater 19 at a constant duty ratio, and even if the power supply voltage fluctuates during rice cooking, no correction is made for it. For this reason, if the power supply voltage drops during rice cooking, the power (heat supply amount) will drop, and it may not be possible to cook delicious rice.

[0003]

As described above, in the conventional electronic jar rice cooker, the change in the power supply voltage is judged only once at the end of the above-mentioned quantity acceptance period, and the rice heating is performed based on the duty ratio thus determined. Therefore, even if the power supply voltage fluctuates during rice cooking, only control with a predetermined duty ratio can be performed. For this reason, there was a drawback that the rice cooker could not follow the fluctuations of the power supply voltage during rice cooking in detail and a good rice cooking state could not be obtained. In order to solve the above problems in the prior art, the present invention provides an electronic jar rice cooker that improves the control means of the rice cooking heater and can cook rice deliciously without being affected by fluctuations in the power supply voltage during rice cooking. The purpose is.

[0004]

In order to achieve the above object, the present invention provides a rice cooking heater for heating a pot to cook rice.
A power supply voltage detection circuit that directly or indirectly detects the power supply voltage of the rice cooking heater, and an output signal from the power supply voltage detection circuit is read at a predetermined time interval in a predetermined process from preheating to the end of rice cooking, and this reading is performed. A rice-cooking heater control circuit for controlling the heating degree of the rice-cooking heater at the predetermined time intervals according to the fluctuation of the value, and when the read value exceeds a preset upper limit value or lower limit value, the read value is read. The electronic jar rice cooker is configured to control the heating degree of the rice cooker heater by fixing the value to the upper limit value or the lower limit value.

[0005]

According to the present invention, the power supply voltage of the rice cooking heater is directly or indirectly detected by the power supply voltage detection circuit. This detection data is read by the rice cooking heater control circuit at predetermined time intervals, and the heating degree of the rice cooking heater is controlled according to the variation of the read value. When the read value exceeds a preset upper limit value or a lower limit value for some reason, the read value is fixed to the upper limit value or the lower limit value by the rice cooking heater control circuit, and based on the fixed value. The degree of heating of the rice cooking heater is controlled.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. still,
The following example is an example embodying the present invention and is not of the nature to limit the technical scope of the present invention. Here, FIG. 1 is a rice cooker heater control circuit diagram of an electronic jar rice cooker according to an embodiment of the present invention (shared with a conventional example), and FIG. 2 is a rice cooker heater control of an electronic jar rice cooker according to an embodiment of the present invention. 2 is a flow chart, FIG. 3 is a time chart in FIG. 2, FIG. 4 is a rice cooker heater control flow chart of an electronic jar rice cooker according to another embodiment of the present invention, and FIG. 5 is a relationship between the power supply voltage and the A / D conversion value in FIG. It is a figure. Since FIG. 1 is common to the conventional example, the description related to FIG. 1 is based on the conventional example. The point that the microcomputer 16 is used as an example of the rice cooking heater control circuit is also similar to the conventional one. However, in FIG. 1, the power supply voltage of the rice cooking heater 19 is indirectly detected by the power supply voltage detection circuit 21 via the transformer 1, the diode bridge 2 and the like as in the conventional case. There is no problem even if it is directly detected. In the rice cooking process, which consists of preheating, quantity approval, rice cooking, spotty and heat retention, the microcomputer 1
The determination of the power supply voltage according to 6 is performed in all steps from preheating to the end of rice cooking. However, the degree of heating can be controlled according to the fluctuation of the power supply voltage at least when cooking rice, which requires particularly fine grained control, and can also be controlled in other predetermined steps.

The procedure for controlling the heating degree of the rice cooking heater by duty ratio control will be described below in the order of steps S1, S2, ... With reference to the flowchart of FIG. The power supply voltage of the rice cooker heater 19 includes resistors 5, 6, 14,
It is detected by the power supply voltage detection circuit composed of the diode 13 and the capacitor 15. That is, as described in the conventional example, the DC voltage, which is the output signal of the power supply voltage detection circuit, changes one-to-one according to the fluctuation of the power supply voltage of the rice cooking heater 19. It can detect the fluctuation of. In the flowchart of FIG. 2, the microcomputer 16 starts reading the DC voltage (S
1). This reading is performed by reading the input voltage of the input port PI1 as described above. For example, the reading is performed in synchronization with the clock signal built in the microcomputer and only the value read at a predetermined time interval is sent to the next step ( S
2). As described in the description of the prior art, the rice cooking relay 18 is turned on and off in response to the on / off operation of the digital transistor 17 for driving the rice cooking relay by the output signal from the microcomputer 16. When the rice cooking relay 18 is in the off state, the rice cooking heater 19 is in the off state, which is irrelevant to the fluctuation of the power supply voltage. Therefore, the reading by the microcomputer 16 is performed only when the rice cooking relay 18 is in the ON state (S3), and only the ON state is A / D converted by the microcomputer 16 (S4). The steps of S1 to S5 are repeated for a predetermined one cycle period until the ON state of the rice cooking relay 18 is terminated (S
5). After that, the microcomputer 16 calculates the duty ratio in the next cycle period based on, for example, the last A / D converted value in the one cycle period (S6) (in some cases, the A / D converted value from the last A / D converted value is used). An average value of D conversion values may be adopted). Rice cooking relay 1 based on this calculation result
The duty ratio of the rice cooking heater 19 is controlled by changing the on-time of 8 (S7). For example, control is performed such that the duty ratio is reduced if the power supply voltage value is high. After that, steps S1 to S7 are repeated for all steps from preheating to the end of rice cooking. A time chart of the duty ratio control is shown in FIG. Although one cycle period is 60 seconds in the figure, this value can be set arbitrarily. For example, it is possible to change the time interval as the rice cooking time elapses. In this way, the microcomputer 16 constantly controls the on-time of the rice-cooking heater 19 according to the change in the power supply voltage, so that it is ideal that rice is always cooked at a constant reference voltage from preheating to the end of rice cooking. It is possible to obtain a good cooked state.

However, the microcomputer 16 caused by some cause
It is also possible to erroneously judge the power supply voltage of. As an extreme example, it may be determined that the power supply voltage is 30 V or 170 V, and the extreme correction is added accordingly, so that the rice may not be cooked well. In case of such an abnormality,
The microcomputer 16 performs control as shown in the flowchart of FIG. FIG. 4 is a flow chart of FIG.
A step (S9) of determining whether the read value in 6 is within a predetermined range and a step (S10) of fixing the read value to a predetermined value in the case of a negative determination are added. Further, FIG. 5 is a relationship diagram between the power supply voltage and the A / D conversion value read by the microcomputer 16. Hereinafter, FIG. 4 and FIG.
Will be described. For example, it is assumed that the reference voltage is AC100V and the fluctuation of the power supply voltage is within ± 20% of the range of 80V to 120V. Power supply voltage fluctuation is 80V to 120V
During this period, the relationship between the power supply voltage and the A / D converted value is linear as shown in FIG. 5, and the duty ratio control according to the fluctuation of the power supply voltage as described above is performed. Here, if a reading value corresponding to 30 V of the power supply voltage is input to the microcomputer 16, the reading value of the microcomputer 16 is 80 V or more.
It is determined that the voltage does not fall within the range of 130 V (S9), and the read value is fixed at the lower limit (S10). That is, the duty ratio is determined as if there was a read value corresponding to the power supply voltage of 80V. On the contrary, when the read value exceeds the upper limit value, the microcomputer 16 fixes the read value at the upper limit value. That is, the duty ratio is determined assuming that there is a read value corresponding to 120 V of the power supply voltage. In this way, it is possible to avoid an abnormal rice cooking state. The upper and lower limits can be set arbitrarily. In the above embodiment, the heating degree of the rice cooking heater is controlled by changing the duty ratio as described above.
In addition, the degree of heating can be controlled also by changing the output of the rice cooking heater 19.

[0009]

Since the electronic jar rice cooker according to the present invention is configured as described above, it is possible to always obtain an ideal rice cooked state without being affected by the fluctuation of the power supply voltage during rice cooked. .. Even if an erroneous input is made for some reason, it is possible to avoid an abnormal cooking state. As a result, even in the summer when the power supply voltage fluctuates significantly,
You can cook delicious rice.

[Brief description of drawings]

FIG. 1 is a rice cooker heater control circuit diagram of an electronic jar rice cooker according to an embodiment of the present invention (shared with a conventional example).

FIG. 2 is a rice cooker heater control flowchart of an electronic jar rice cooker according to an embodiment of the present invention.

FIG. 3 is a time chart in FIG.

FIG. 4 is a rice cooker heater control flowchart of an electronic jar rice cooker according to another embodiment of the present invention.

5 is a relationship diagram between the power supply voltage and the A / D conversion value in FIG.

[Explanation of symbols]

 16 ... Microcomputer (rice cooking heater control circuit) 17 ... Digital transistor 18 ... Rice cooking relay 19 ... Rice cooking heater 21 ... Power supply voltage detection circuit

Claims (2)

[Claims] 1. A rice cooking heater that heats a rice cooker to cook rice, a power supply voltage detection circuit that directly or indirectly detects a power supply voltage of the rice cooking heater, and an output signal from the power supply voltage detection circuit from preheating. And a rice-cooking heater control circuit for controlling the heating degree of the rice-cooking heater at a predetermined time interval in accordance with a change in the read value in a predetermined process until the end. A characteristic electronic jar rice cooker. 2. The heating degree of a rice cooking heater is controlled by fixing the read value to the upper limit value or the lower limit value when the read value exceeds a preset upper limit value or lower limit value. Electronic jar rice cooker.