JPH0655189B2 - rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a rice cooker that is most suitable for "cooking".

(B) Conventional technology Conventionally, a rice cooker having a plurality of heating patterns and capable of performing "rice porridge", "double cooking", "rice cooked", "cooking", etc. is disclosed in, for example, JP-A-55-148522. Has been done. A problem with such a rice cooker is a control method of "cooking" in which seasonings such as soy sauce are added. In other words, when rice is cooked with soy sauce, the soy sauce tends to burn, and when burnt, the burntness is very dark and not well-made. . The main cause of this burning is that the temperature of the pot continues to rise due to the residual heat of the heater even if the heating is stopped when the temperature reaches the cooking temperature. In addition, such burns due to overshooting are not limited to special cases such as "cooking", but are also a problem in electric rice cookers that have high wattage heaters to have the same performance as gas rice cookers. ing. As a method to solve this, it is possible to drive the timer from a predetermined temperature and reduce the heating amount of the heater after a predetermined time, but the timer driving point is fixed based on the contact state of the temperature sensor and the pan, the ambient temperature, etc. However, it may be difficult to maintain the minimum boiling time required for cooking rice, which may cause inconvenience such as simmering raw rice or prolonging cooking time more than necessary.

(C) Problems to be Solved by the Invention In consideration of the above-mentioned drawbacks, the present invention is intended to prevent the occurrence of burns and to prevent the cooked rice from being cooked longer or the cooking time longer than necessary.

(D) Means for solving the problems The present invention is a pan for storing cooked rice, a heating means for heating the pan, a driving means for driving the heating means, and a temperature for detecting the temperature of the pan. Detecting means, heating control means for controlling the driving means based on the output of the temperature detecting means to increase or decrease the heating amount of the heating means, and a boiling time determining means,
It is determined whether or not a predetermined boiling time required for rice cooking has passed by the boiling time determination means from the time when the cooked rice reaches a boiling state until the completion of cooking, and when the predetermined boiling time elapses, the heating means of the heating means In the rice cooker that reduces the heating amount, the boiling time determination means is a temperature gradient detection means that sequentially detects a temperature gradient at predetermined time intervals based on the output of the temperature detection means, and a predetermined value or less of the temperature gradient detection means. And a number of times determining means for determining whether or not the temperature gradient has occurred a predetermined number of times, and the determination reference time of the predetermined boiling time required for rice cooking is set by the product of the predetermined time interval and the predetermined number of times. Is.

(E) Action Since the present invention is configured as described above, when the cooked food approaches the boiling state, the detection value of the temperature gradient detection means gradually decreases, and when the cooked food becomes a predetermined value or less, the number of times it becomes the predetermined value or less It is counted by the number-of-times determining means. While the boiling of the cooked rice is continued, the detected value of the temperature gradient detecting means is maintained at almost 0 and the count of the number of times determining means is continued. When the boiling is further continued and a predetermined number of times is determined by the number-of-times determination means, that is, when a predetermined time determined by the product of the time interval of temperature gradient detection and the predetermined number of times has elapsed, the heating amount of the heating means is reduced. Prevent burning when rice is cooked. In this way, the boiling time required for cooking rice is determined by the relative number of times the temperature gradient is equal to or less than the predetermined value, so even if the contact state between the temperature detector that constitutes the temperature detecting means and the pan is poor. The boiling duration can be reliably determined.

(F) Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 8. FIG. 1 shows a schematic block diagram of a rice cooker of the present invention, (A) is a pan, (B) is heating means for heating the pan, (C) is driving means for driving the heating means, and (D) ) Is a temperature detecting means for detecting the temperature of the pot, (E) is based on the output of the temperature detecting means, the temperature gradient before boiling is detected, the amount of cooked rice detecting means for detecting the amount of cooked rice based on this, ( After the rice cooking amount detecting means detects the rice cooking amount, F) sequentially detects the temperature gradient based on the output of the temperature detecting means (D), and the temperature gradient of a predetermined value or less is the rice cooking amount detecting means (E). The boiling time determination means for determining whether or not the number of times has been determined by (G) is the temperature detection means by starting the operation according to the boiling time determination means.
(D) a dry-up determination means for sequentially detecting the temperature gradient based on the output of the output and determining whether or not a temperature gradient of a predetermined value or more has occurred, (H) controls the driving means (C), and heats means
(B) is a heating control means for controlling the heating amount, the heating amount is reduced to the heating amount determined by the cooking amount detecting means (E) according to the boiling time determining means (F), and the dry-up determining means (G).
The heating is stopped according to. Incidentally, A of FIG.
The numbers in parentheses of D are numbers corresponding to the members of FIGS. 2 to 4 described later.

An example of the condition in FIG. 1 will be described below with reference to FIGS. 2 to 8. FIG. 2 is a sectional view of the rice cooker of the present invention,
(1) is an outer frame, (2) is a container, (3) is a heater provided on the inner bottom of the container (2), (4) is a pot that is stored in the container (2) and placed on the heater, (5) is a negative characteristic thermistor that detects the temperature of the outer bottom surface of the pot.

FIG. 3 is an electric circuit diagram of the rice cooker of the present invention. (6) is a DC power supply circuit, (7) is a time base circuit that shapes the waveform of the AC power supply (8), and (9) is the thermistor (5 (10) is a relay contact (10A) connected in series with the heater (3), a relay coil (10B), a transistor (10C) for driving the relay coil and an inverter (10) for a driver.
Drive circuit consisting of (D), (11) is the time base circuit
A microcomputer which inputs the output signals of (7) and the temperature detection circuit (9) and controls the drive circuit (10) in accordance with the input signal.

FIG. 4 shows a basic configuration of the microcomputer (11), which includes a CPU (11A), a RAM (11B), a ROM (11C), an input port (11D), an output port (11E) and the temperature detection circuit ( It is composed of an A / D converter (11F) for A / D converting the output signal of 9). CPU in ROM (11C)
The program that controls (11A) is written in the CP
U (11A) follows the input port (11
External data required from D) is fetched, or arithmetic processing is performed while exchanging data with RAM (11B), and the processed data is output to output port (11E) as necessary. Output and this output port
(11E) is an "H" level signal or "L" to the drive circuit (10).
A level signal will be output.

The program written in the ROM (11C) is shown in a flowchart of FIG. Further, the relationship between the temperature detected by the thermistor (5) and the time when it is operated according to the program is shown in FIGS. 6 to 8. Here, the operation of the rice cooker will be described with reference to FIGS.

First, when a predetermined amount of rice and water are put in the pot (4) and the power is turned on, the CPU (11A) starts control according to the program in the ROM (11C). First, the drive circuit (10) is controlled to cause the heater (3) to generate electric power with the FU11 (W) (800 (W)) (step). Here, the power control in the present invention will be described. The power control of the present invention is, for example, duty control, and the cycle is set to 16 seconds (considering the life of the relay contact (10A)). If it is 800 (W), the heater (3) is turned on for 16 seconds.
If N and 400 (W), the heater (3) for 8 seconds is turned on and the heater (3) for 8 seconds is turned off.

Then, the temperature of the pot (4) rises, and the thermistor (5) becomes To.
When (℃) is detected (step,), drive circuit (10)
To control the electric power of the heater (3) to 0 (W) (step). And the thermistor when t minutes (3 minutes) have passed
The amount of cooked rice is detected by the detection temperature of (5) (step,
,). According to the experimental data, if the temperature is below T1 (℃), the amount of rice cooked is "Large", if it is above T1 (℃) and less than T2 (℃), the amount of rice cooked is "Medium", and above T2 (℃), the rice is cooked The amount is set to "small". Then, RAM (1
1B) N (area for storing a value to be compared with the contents of a register (C) described later), T3, power 1 and power 2 are stored in respective areas such as steps. The relationship between the respective data is set as follows.

NL ＞ NM ＞ NS T3L (106 ℃) ＞ T3M (103 ℃) ＞ T3S (100 ℃) Power 1L (650 (W)) ＞ Power 1M (550 (W)) ＞ Power 1S (450 (W)) Power 2L (450 (W))> power 2M (400 (W))> power 2S (350 (W)) The meaning of these data will be described later.

Then, after the rice cooking amount is detected by steps 1 to 3, the drive circuit (10) is controlled to supply the electric power of the heater (3) to FU11.
Return to (W) (800 (W)) (step). The thermistor (5) is R
Temperature (T3L, T3M or T3) stored in the T3 area of AM (11B)
When S) is detected (step,), the drive circuit (10) is controlled to turn on the heater (3) with the electric energy (electric power 1L, electric power 1M or electric power 1S) stored in the electric power 1 area of the RAM (11B). Heat generation (step), register (C), register (n),
0 is set to the address for specifying the temperature data storage area θn of the ROM (11C) (step). Then, when Δt seconds elapse after this, the temperature data (θo) at that time is stored in the 0th area of the θn area of the RAM (11B),
Add 1 to the contents of register (n). And register
Temperature data (θ) every Δt seconds until the content of (n) becomes M
1, θ2 ... θM) are sequentially stored in the θn area of the RAM (11B) (steps, ∼). If the thermistor (5) detects θlim (135 ° C) during the above operation, the drive circuit (10)
To control the electric power of the heater (3) to 0 (W), and the rice cooking is completed (step,). This is considered to be in a dry-up state when the temperature of the pot (4) reaches 135 ° C, and is for preventing abnormal overheating due to empty cooking.

Then, when the content of the register (n) becomes M, θn-1−θn−
n (here, θn-1−θo) is calculated (step). If this value (Δθ) is larger than ΔθS, return to step or repeat the same operation as above, and if ΔS or less, register (C) Add 1 to the content of (step,). And the contents of this register (C) is RAM (11B)
It is determined whether or not the value is in the N region of (step), and if not, the process returns to step and the same operation as above is repeated. Steps described above ~
Is the calculation of the difference between the temperature Δt · (n−1) seconds before and the current temperature based on the output signals of the temperature detection circuit (9) and the time base circuit (7), that is, in FIG. Is 11)
.Theta.10-.theta.o, .theta.11-.theta.1, .theta.12-.theta.2 ... Are calculated at .DELTA.t second intervals to obtain .DELTA..theta.
It has a function of determining whether or not a value equal to or less than θS has occurred NL, NM or NS times and detecting the point t4 in FIG.

Then, when the content of the register (C) reaches the value of the N area, the content of the register (n) is set to 0 (step), the drive circuit (10) is controlled, and the electric power of the heater (3) is turned on. The amount of power stored in the two areas (power 2L, power 2M or power 2S) is reduced (step). And the steps after this ~
Is the M of the step
To M ′ and Δθ ← θ (n-1) −θ (nM) of the step is Δ
θ ′ ← θ (n-1) −θ (nM ′) and Δ
The operation in which θ ≦ θS is changed to Δθ ′ ≧ Δθ ′S is performed. This is the calculation of the difference between the temperature before Δt · (M′−1) and the current temperature based on the output signals of the temperature detection circuit (9) and the time base circuit (7), that is, FIG. 8 (here M ′ Is set to 7) ... θn-2−θn-8, θ
Calculations of n-1−θn-7 and θn−θn-6 are performed at Δt second intervals to obtain Δθ ′ in each, and it is determined whether or not a value of Δθ ′S or more has occurred, and FIG. It has the function of detecting the end of rice cooking (dry-up). The above Δ
t, M, M ′, ΔθS, Δθ ′S are determined by experimental data.

Then, when Δθ'S or more, the drive circuit (10) is controlled and the electric power of the heater (3) is set to 0 (W) to complete the rice cooking (step).

In the present invention, the electric power of the heater (3) is set to 0 at the end of rice cooking.
(W) was used, but it may be set to about 70 (W) and kept warm thereafter. In the above operation, the power of the heater (3) is supplied to the RAM (11
Time point (t ₄ ) when the amount of electric power stored in the electric power 2 area in B) is reduced.
Is determined based on the relative value of the temperature gradient, and regardless of the contact state of the thermistor (5) and the pan (4) and the influence of ambient temperature, boiling will start even if it is repeated for the same amount of cooked rice. The time from time point to t ₄ can be made substantially constant. Note the time until t ₄ from the boiling start point will be determined NL, NM, the value of NS. Therefore, these NL, NM, NS are the optimum amount of power for each rice cooking amount (power 1L, power 1M, power 1S)
When the rice is cooked in, it is preferable that the minimum required boiling time for the amount of electric power is obtained by an experiment and then determined. Further, in the present invention, since the end point of cooking rice is also determined based on the temperature gradient, the pot temperature at the end point of cooking rice can be made substantially constant even if it is repeated for the same amount of rice. The rising state can be made substantially constant.
Further, the rice cooking can be finished at, for example, ₃ to ₄ deg from the time point t4, and the occurrence of burnt can be prevented. Incidentally, t ₄
Power from the point to the end of rice cooking (power 2L, power 2M, power 2
It is preferable that S) is determined in consideration of the cooked state and the occurrence of burntness in each amount of cooked rice.

(G) Effect of the invention Since the present invention is configured as described above, it is possible to prevent the occurrence of burns when "cooking" or to increase the heater to high wattage, and it is necessary for cooking rice. It is possible to secure a sufficient boiling time and prevent the cooking time from being boiled or the cooking time longer than necessary.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of the rice cooker of the present invention, FIG. 2 is an explanatory view showing a schematic structure of the rice cooker, FIG. 3 is a schematic electric circuit diagram of the rice cooker, and FIG. 4 is shown in FIG. 5 is an explanatory diagram of the microcomputer shown in FIG. 5, (a), (b) and (c) of FIG. 5 are flow charts showing a series of operations of the program, and FIG. 6 is also the temperature detected by the thermistor and the time from the start to the end of rice cooking. FIG. 7, FIG. 7 is a detailed characteristic diagram of a portion A of FIG. 6, and FIG. 8 is a detailed characteristic diagram of a portion B of FIG. (3) …… Heater, (4) …… Pot, (5) …… Thermistor, (9)
...... Temperature detection circuit, (10) …… Drive circuit, (11) …… Microcomputer, (11A) …… CPU, (11B) …… RAM,
(11C) …… ROM, (11D) …… Input port, (11E)
…… Output port.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Arinaka 3-201, Minami-Kichikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (56) Reference JP-A-59-63425 (JP, A) JP 62-142519 (JP, A) JP 62-16718 (JP, A)

Claims (1)

[Claims] 1. A pan for storing cooked rice, a heating means for heating the pan, a driving means for driving the heating means, a temperature detecting means for detecting the temperature of the pan, and an output of the temperature detecting means. Based on the heating means for controlling the driving means to increase or decrease the heating amount of the heating means, and a boiling time determination means, the boiling time between the rice cooked until the rice is cooked In the rice cooker that determines whether or not the predetermined boiling time required for rice cooking has elapsed by the determination means, and reduces the heating amount of the heating means when the predetermined boiling time has elapsed, the boiling time determination means is configured to detect the temperature. A temperature gradient detecting means for sequentially detecting temperature gradients at predetermined time intervals based on the output of the means, and a number-of-times determining means for determining whether or not a temperature gradient equal to or less than a predetermined value of the temperature gradient detecting means has occurred a predetermined number of times. Prepare and cook Cooker being characterized in that a configuration for setting the product of the predetermined number of times and said predetermined time interval criterion time of a predetermined boiling time required.