JPH0127724B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rice cooker that uses a microcomputer to control the amount of power of a heater.

In this type of rice cooker, the temperature rise characteristics of cooked rice during cooking vary depending on the amount of rice to be cooked and the amount of electric power of the heater, and are not uniform and have large differences in parts. In particular, there is a big difference in the time it takes for rice to boil when cooking a small amount of rice and cooking a large amount of rice, even with the same amount of electricity.
It is affected by how well the rice is cooked.

In other words, in the conventional method of detecting the amount of cooked rice by detecting the temperature rise rate of the inner pot and decreasing the amount of power of the heater from the middle of heating up the rice, the amount of rice cooked is the same, but the amount of power of the heater is reduced due to the voltage difference. Due to external fluctuation factors such as temperature differences, differences in room temperature and water temperature, variations in temperature detection, and differences in heat transfer due to differences in structure, the position at which power is reduced will shift significantly, affecting the cooking time and causing overcooking or boiling. Even cooking cannot be achieved due to insufficient maintenance time.

In addition, due to the external fluctuation factors mentioned above, it is difficult to accurately determine the amount of cooked rice, and when the amount of cooked rice is large,
If the temperature is detected as medium, the power is switched to medium heat before the rice has sufficiently boiled, and as a result, the temperature of the rice rises unevenly, resulting in uneven cooking.

On the other hand, if the amount of rice to be cooked is small, more electricity than necessary will be used to boil the rice, resulting in overcooking or
The water in the inner pot evaporates in a short period of time, resulting in insufficient boiling time and problems such as insufficient gelatinization of rice starch.

Furthermore, the cooking time varies depending on the amount of rice to be cooked, which is inconvenient for the user.

Therefore, in view of the above-mentioned conventional circumstances, the present invention detects the weight of the main body or inner pot, determines the amount of rice to be cooked, and controls the heat by supplying the optimum power at the start of cooking, and also adjusts the amount of water relative to the amount of rice to be cooked. To provide a rice cooker with further improved usability and rice cooking performance by determining and displaying the following information.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Figures 1 and 2, 1 is the rice cooker main body;
Reference numeral 2 denotes an outer pot disposed within the main body 1; 3 an inner pot detachably housed within the outer pot; 4 a heater provided at the inner bottom of the outer pot 2; and 5 above the inner pot 3. The outer lid of the completed body is equipped with an inner lid 5a that closes the opening, 6 is a temperature sensor provided so as to be in close contact with the bottom wall of the inner pot 3, and 7 is a temperature sensor that is attached to the main body 1 so as to cover the bottom opening of the main body 1.
A synthetic resin bottom frame 9 with a mounting plate 8 attached to the top surface is inserted into the inside of the bottom frame 7,
A synthetic resin bottom lid on which a microcomputer 18 (to be described later) is disposed, and the inner flange 7a of the bottom frame 7
A compression spring 10 is installed between the outer flange 9a of the bottom cover 9 and
is installed. Reference numeral 11 denotes an adjustment screw that connects the bottom frame 7 and the bottom cover 9, and also serves to adjust the facing distance between a pair of electrodes 17' and 17'', which will be described later.

12 is attached to the main body 1, and the power switch 1
3. Rice cooking switch 14, 2-degree cooking selection switch 1
5 and an operation panel each having a display section 16 for displaying the rice cooking process, and 17 a weight sensor, which is a pair of electrode plates 1 attached to the bottom frame 7 and the bottom lid 9.
7', 17'' and the compression spring 10.

Reference numeral 19 denotes a bottom plate that closes the bottom opening of the bottom cover 9.

Next, the control circuit block diagram shown in FIG. 3 will be explained. 20 is a heater 4, a weight sensor 17
The power supply 21 for driving the electrodes 17', 17'' and the microcomputer 18 is a triax connected in series to the power supply 20 and the heater 4, and when a signal is input to its gate terminal G, it turns on (conducts). If no signal is input, it is turned off (cut off) and controls the energization rate to the heater 4.

22 inputs the signal from the temperature sensor 6,
The target value and temperature sensor 1 stored in advance in the memory 18a of the microcomputer 18
A comparator 23 performs a comparison with the measured value of 6, and 23 is an oscillation circuit, in which a part of the capacitor constituting this oscillation circuit is replaced with an electrode capacitance.

That is, the electrode capacitance changes as the distance between the pair of electrodes 17' and 17'' increases or decreases in proportion to the total weight of the inner pot 3 containing rice and water and the main body 1, and this change The amount of cooked rice is detected as a change in the oscillation state, and is input as an input signal to the input circuit 18c of the microcomputer 18. 18b and 18d are the control circuit and output circuit of the microcomputer 18, and 24 is a warning signal. It is also a buzzer for notification.

In the above configuration, when the inner pot 3 containing rice and water is installed inside the main body 1, the main body 1 including the outer lid 5, outer pot 2, heater 4, bottom frame 7, mounting plate 8, temperature sensor 6, etc. The total weight W ₁ (hereinafter referred to as product weight) and the inner pot 3 containing rice and water, W ₀ , is added to the compression spring 10 , and the compression spring 10 moves in the compression direction in proportion to the total weight W ₀ . Displace.

At this time, one of the pair of electrode plates 17', 17'', which is attached to the bottom frame 7, moves downward by the displacement of the compression spring 10. The capacitance C changes in inverse proportion to the distance between the electrodes. (FIG. 5) That is, if the dielectric constant of air is ε, the area of the electrode plate is S, and the distance between the electrode plates is d, the capacitance C is expressed by the following equation.

C=εS/d...(ε and S are constants) This change in capacitance C is converted into a change in the oscillation frequency f of the oscillation circuit 23, but at this time, the oscillation frequency f is inversely proportional to the capacitance C. do. (Fig. 6) f∝1/C (However, the resistance R is constant.) Therefore, from both equations, the oscillation frequency f is proportional to the distance d between the electrodes. (Fig. 7) f∝d... On the other hand, it is clear from the characteristics of the compression spring 10 that the distance d between the electrodes and the weight W ₀ applied to the compression spring 10 are proportional. (Fig. 8) W ₀ ∝d... From the equation, it can be seen that the weight W ₀ and the oscillation frequency f have a linear linear relationship. (Figure 9) f∝W ₀ ... Furthermore, as shown in Figure 4, the weight of rice and water
Rice cooking amount determination weight W ₀ which is the sum of W ₂ and product weight W ₁
Since the amount of cooked rice V is proportional to (W ₀ ∝V), the conclusion is that the oscillation frequency f is proportional to the amount of cooked rice V, as shown in FIG.

f∝V... Also, due to the difference in weight detection structure, the weight detected by the weight sensor 17 consisting of the bottom frame 7, compression spring 10, electrode plates 17', 17'', bottom cover 9, etc. Instead of the sum of weight W ₂ and product weight W ₁ (W ₀ ), it is the weight of rice and water W ₂ plus inner pot 3, or the weight of rice, water, and inner pot 3 plus outer pot 2 and heater 4. It goes without saying that if the weight of rice and water (W ₂ ) is included, such as the weight of the temperature sensor 6, etc., then the above equation holds true regardless of the weight of any block.

As an example, the rice cooking process will be specifically explained below.

When the inner pot 3 containing rice and water is placed inside the main body 1 and the power switch 13 is turned on, the microcomputer 18 is powered up and starts operating.

A change in the capacitance C of the weight sensor 17 is converted into a change in the oscillation frequency f via the oscillation circuit 23, and is input to the input circuit 18c of the microcomputer 18.

Then, the microcomputer 18
Based on the experimental results, the memory 18a stores, for example, 1.
Since the number of counts of the pulse signal of the oscillation frequency f during a certain time T for the reference rice cooking amount such as 2 cups, 3 cups, ..., 9 cups, 10 cups, etc. is stored as data, By comparing the count entered into the input circuit 18c with the data in the memory 18a, the amount of rice in the inner pot 3 can be automatically determined.

At this time, for example, the optimal water addition ratio for each standard rice cooking amount from 1 to 10 cups is approximately determined, so in addition to the width of the count number to be determined as each standard rice cooking amount, the number within the count number width is determined in advance. The weight data at the optimum water addition ratio for each standard rice cooking amount at a certain place, that is, the count width, is stored in the memory 18a, and after determining each standard rice cooking amount from the weight information from the weight sensor 17, the judgment is performed. By comparing the weight data at the optimal water addition ratio of the reference rice cooking amount determined with the weight information from the weight sensor 17, it becomes possible to determine how much or how much water the user has added.

At this time, there may be variations in the weight of rice in each standard cooking amount, for example, the weight of rice per cup, or differences in taste sensitivity among users. There is an element of uncertainty that some people prefer rice that has a lot of moisture and is a little sticky, and others prefer rice that has less moisture and is a little dry when the rice is cooked. Needless to say, you have to judge the amount of water by holding it.

Note that in this explanation, one cup is considered to be one cup.

As an example, to explain with Figure 11, Wa
(Min) is the minimum value that determines the standard cooking amount as 2 (that is, 2 cups = 2 cups), Wa (Max) is the maximum value that determines the standard cooking amount as 2, and weight information from the weight sensor 17 is Wa (Min) and Wa
(Max), the standard cooking amount at that time is determined to be 2. The minimum and maximum values of each standard rice cooking amount that can be cooked are stored in advance in the memory 18a.

In FIG. 11, the minimum value for determining the standard rice cooking amount to be 3 (that is, 3 cups = 3 cups) is Wb (Min), and the maximum value is Wb (Max). And Wah and Wal
are the upper and lower limits of the weight when the standard cooking amount of rice is 2 and the appropriate water addition ratio, respectively, and Wa between them is the standard weight when the standard cooking amount of rice is 2 (the sum of the weights of rice and water at the optimal watering ratio) , and the upper limit Wah and the lower limit
The value is an intermediate value of Wal, and each value is stored in advance in the memory 18a for each reference rice cooking amount.

Weight information from weight sensor 17 and memory 18
Compare the maximum and minimum values of each reference rice cooking amount in a.

At this time, the weight widths of the respective reference rice cooking amounts are set so as not to overlap. In other words, since the maximum value of one previous standard rice cooking amount is set in advance to be smaller than the minimum value of the next standard cooking amount, one standard cooking amount is uniquely determined based on the weight information of one weight sensor 17. Kimimaru.

When the weight information at that time is, for example, in the area (a) between Wah and Wa (Max) of the standard rice cooking amount 2, it is determined that water is large in the standard rice cooking amount 2, and Wal When it is in the area (c) between and Wa (Min), it is determined that the water is too little for the standard rice cooking amount 2, and when it is in the area (b) between Wah and Wal,
It is determined that the standard cooking amount is 2.

Between the maximum value and the minimum value of each standard rice cooking amount, in Fig. 11, the maximum value Wa of standard rice cooking amount 2
The region (d) between (Max) and the minimum value Wb (Min) of the standard rice cooking amount 3 is the water amount judgment impossible region where it is judged that the water amount cannot be determined because the weight is outside the standard rice cooking amount. .

The memory 18 of the microcomputer 18 also stores information about each area of (a), (b), (c), and (d) of each standard rice cooking amount.
It is pre-programmed in a. Therefore, when the microcomputer 18 receives the input signal from the weight sensor 17, the control circuit 18b determines the reference rice cooking amount V from the rice cooking amount determination weight _W0 , and
Each data regarding the standard cooking amount (as an example)
The amount of water is determined by comparing with Wa (Min), Wa (Max), Wah, Wal, etc., and the content of the determination is displayed on the display unit 16. For example, the display contents may include items A to D in FIG. 11.

In this way, with the inner pot 3 installed, before energizing the heater 4, it is possible to determine the amount of rice to be cooked, that is, whether it corresponds to the preset standard amount of rice to be cooked, and to adjust the amount of water to the determined standard amount of rice to be cooked. This makes it possible to simultaneously determine and display whether or not the information is appropriate.

Next, when the rice cooker switch 16 is pressed, power is started to be applied to the heater 4, and the rice and water in the inner pot 3 begin to be heated. Here, with reference to FIG. 12, the difference between the rice cooking method of the conventional method of determining the amount of cooked rice based on the temperature rise gradient of a temperature sensor and the rice cooking method of the present invention will be explained.

In the conventional method, the amount of rice to be cooked is determined based on the temperature rise gradient after rice cooking starts, so it is impossible to control the heat power at the beginning of rice cooking. That is, in FIG. 12, _TR is the room temperature, and _t6 is the time required for the preset temperature Td to Te. In the conventional method, the amount of cooked rice is determined based on this _t6 . Therefore, until the temperature sensor reaches Te and determines the amount of rice to be cooked, it is not possible to control the heat, and it is not possible to determine whether the amount of water is too much or too little. Moreover, if the room temperature T _R exceeds Td, an error occurs in the data of T ₆ , which has the disadvantage that it becomes impossible to judge the amount of rice cooked.

However, according to the present invention, which determines the amount of cooked rice based on weight, regardless of the room temperature _TR at the time of starting rice cooking,
In addition, the amount of rice to be cooked can be determined at the same time as rice cooking starts, and the firepower can be controlled immediately to match the amount of rice being cooked. Problems such as rice that only the surface becomes gelatinized and the core remains can be solved. Further, unlike the conventional method, errors in determining the amount of rice to be cooked due to voltage fluctuations and variations in the wattage of the heater 4 are no longer caused.

As described above, according to the present invention, when rice cooking is started and the heating power at this time is set to high heat, the cooked rice in the inner pot 3 cooks as can be seen from the control example [ ] (5 cups) shown in FIG. Letting Ta be the temperature of the temperature sensor 6 at the boiling point, the heating can be reduced to medium heat after t ₁ has elapsed and the temperature sensor 6 reaches the temperature Ta.

When the water in the inner pot 3 runs out, the temperature at the bottom of the inner pot rises rapidly, and when the temperature sensor 6 reaches the temperature Tb, the heater 4 is turned off and the rice cooking mode is switched from rice cooking to uneven cooking.

In addition, in the above example, 1 go, 2 go, 3 go
Go, ..., 9 go, 10 go and the standard cooking amount 1 for every 1 go,
2, 3, ..., 9, 10, but 1 go, 1.5 go, 2
You can set the standard rice cooking amount in 0.5 go increments, such as 9.5 go, 10 go, etc., or the increments should be set so that there is not more than one standard rice cooking amount for one weight value. Good.

As described above, the present invention detects the weight of the main body or the inner pot, determines the amount of rice to be cooked, and controls the power consumption of the heater, so that it is possible to control the heating power commensurate with the amount of rice to be cooked as soon as the rice starts cooking. , it is possible to obtain an ideal rice cooking curve throughout the rice cooking process.

In addition, since it is simultaneously determined whether the amount of water is appropriate for the amount of rice to be cooked and displayed on the outside, the user can cook rice according to his or her preference, and a rice cooker that is even more user-friendly can be provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a rice cooker showing an embodiment of the present invention, and FIG. 2 is a front view of an example of the operation panel thereof.
FIG. 3 is a block diagram showing an example of the control circuit, and FIG. 4 is an explanatory diagram showing the relationship between the amount of rice cooked and the weight.
Figures 5 to 10 are characteristic diagrams of each displacement constant of the weight sensor, Figure 11 is an explanatory diagram showing an example of water amount determination,
FIG. 12 is a rice cooking control diagram showing an example of rice cooking using a conventional rice cooker and a rice cooker according to the present invention. In the diagram, 1...Main body, 2...Outer pot, 3...Inner pot,
4... Heater, 6... Temperature sensor, 17... Weight sensor, 17', 17''... Electrode, 18... Microcomputer.

Claims (1)

[Claims] 1. A main body, an outer pot disposed within the main body, an inner pot removably housed within the outer pot, an outer lid that closes the opening of the inner pot, and a heater provided at the inner bottom of the outer pot. and the maximum amount of rice cooked in each standard.
A memory that stores the minimum weight range, a weight detection means that detects the weight of the main body or the inner pot, and a comparison between the weight detected by the weight detection means and the information in the memory, and determines which standard rice cooking amount the detected weight is. a control means for determining whether the weight is within the range of , and controlling energization to the heater so as to supply a preset amount of electric power corresponding to the determined reference rice cooking amount;
water amount determining means for determining whether the amount of water for the reference rice cooking amount is appropriate or not based on where the weight detected by the weight sensing means is within the weight range in the memory of the determined reference rice cooking amount; A rice cooker comprising: display means for externally displaying the result determined by the water amount determination means.