JPS6018128A - Heater control of rice cooker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical Field) The present invention is based on the set temperature and the temperature of a thermosensor that detects temperature changes of the food to be cooked through the pot while increasing the set temperature sequentially at regular intervals. The present invention relates to a rice cooker that heats and raises the temperature of food by controlling energization to the heater, and particularly relates to a method of controlling the heater.

(Prior art) In general, in a device that controls the energization of the heater based on the set temperature and the temperature of the thermosensor, the heater is energized immediately when the temperature of the thermosensor reaches the set temperature, and vice versa. A control method is adopted in which the power supply to the heater is immediately stopped when the temperature becomes lower than a set temperature.

However, when such a conventional control method is applied to control the heater in the rice cooker that is the object of the present invention, it is not possible to achieve good control.

In other words, in the conventional control method, if the temperature of the thermosensor is lower than the set temperature, the heater is continuously energized for a long time regardless of the time, so when the temperature of the thermosensor reaches the set temperature, the energization to the heater is stopped. After that, the overshoot of the thermosensor temperature due to residual heat is very large, and the thermosensor temperature deviates from the set temperature by a large amount.It is difficult to control the rice cooker's heater to gradually increase the set temperature at regular intervals. (Purpose) The present invention has been made in view of the above problems, and by setting a limit on the continuous energization time to the heater, it is possible to control the thermostat with respect to the set temperature. By keeping the overshoot of the sensor temperature to a small level, and in addition, when the heater stops energizing, the energization is maintained for at least a certain period of time regardless of the temperature, thereby reducing the difference between the temperature rise of the thermosensor due to the difference in heat capacity and the temperature rise of the food being cooked. This system absorbs time lag and reduces the temperature difference between the top and bottom of the food to be cooked, making it possible to perform highly accurate and better control.

(Example) Examples of the present invention shown in the drawings will be described in detail below.

First, FIG. 1 shows a schematic structure of the rice cooker of the present invention.

In the figure, the main body of the 1-jar rice cooker, 2 is an outer pot, 3 is a hot plate type rice cooker heater installed at the inner bottom of the outer pot 2, and an inner pot that can be moved in and out of the 4-jar outer pot 2 to store food to be cooked. , 5 is a heat-retaining heater provided on the outer surface of the outer pot 2, 6 is a thermosensor such as a thermistor that is in contact with the center of the outer bottom surface of the inner pot 4 and detects temperature changes of the food to be cooked, and 7 is provided on the outer surface of the outer pot 2. 8 is an operation panel provided on the outer surface of the main body 1; 9 is an operation panel 8;
This is a control board built into the Although not shown in the drawings, it goes without saying that an inner lid for opening and closing the opening of the inner pot 4 and an outer lid for covering the outside of the inner pot 4 are provided as is well known in the art.

The operation panel 8 has a time display section 10 as shown in the second figure.
It also has an operation status display section 11 for heat retention, double cooking/uncooking, preheating/cooking, etc., as well as a timer set key 12 and various control keys 13.

Next, FIG. 3 is a circuit diagram in which the present invention is implemented by a microcomputer, in which the rice cooking heater 3 is connected to the AC power supply 15 through the contacts of the rice cooking relay 14, and the rice cooking relay 1
A series circuit consisting of contacts of a heat-retaining heater 5, a heat-retaining thermal reed switch 7, and a heat-retaining relay 16 is connected to the contact point 4 in parallel.

The rice cooking relay 14 and the heat retention relay 16 are controlled to be turned on and off by the microcomputer described later.
By controlling the electricity supply to the rice cooking heater 3 and the warming heater 5, rice cooking or warming operation is executed. In addition, both relays 14 and 16 are provided on a control board 9, and this board 9 is also provided with a microcomputer, a time display element, a light emitting diode, a switch, etc., and the time display element, light emitting diode, and switch are operated. Each display section 10.11 and various keys 12.13 of the panel 8 are made to correspond to a predetermined relationship. The power for the control section as described above is obtained from an AC power source via a transformer 17.

FIG. 4 is a block diagram of the entire control circuit. In FIG. 4, 18 is a microcomputer 9, mainly a central processing unit (hereinafter referred to as CP'U) 19, and an electronic timer 2.
0, a read-only memory (hereinafter referred to as ROM) 21, a random access memory (hereinafter referred to as RAM) 22, and an interface (input/output signal processing circuit) 23. The ROM 21 stores the control program for the CPU 9, and the RAM 22 stores the control program for the CPU 9.
used as data memory.

The CPU 19 reads the status of each part on the input side via the interface 23 and also reads the control program from the ROM 21 to perform preheating, capacity determination,
Judging processes such as boiling, double-cooking, uneven cooking, and keeping warm,
The heating unit necessary for executing the process is controlled via the interface 23, and the process transition is performed by the electronic timer 20 in cooperation with the CPU 1'9. Incidentally, the electronic timer 20 counts a predetermined time according to instructions from the CPU 9 and outputs a signal after the predetermined time.

In the above configuration, the control will be explained in detail below.

First of all, FIG. 5 is a main flowchart of the rice cooker of the present invention, in which the following steps are sequentially executed: start rice cooking, heat the second rice, determine secondary preheating capacity, finish cooking, double-cook/uniformly cook, and keep warm. Each process other than the cooking process and the warming process is executed for a predetermined period of time (constant).Also, the cooking process ends only when the temperature of the food is detected.
It becomes approximately constant by adopting a control method that will be described in detail later. Incidentally, FIG. 6 is a curve diagram showing the relationship between the elapsed time from the start of rice cooking to keeping it warm and the temperature change of the thermosensor 6. Control of each process will be explained below.

〇 -Next, turn on the control key 13 for secondary preheating process rice cooking/timer start,
By storing this in the storage means A in the CPU 19 and reading out the control program contents in the ROM 21 corresponding to the stored contents, the chart from 70 to the primary heating process shown in FIG. Control is performed as shown in chart 70 of the secondary preheating step.

-＼ In the primary heating process, when the rice cooking/timer start control key 13 is turned on, the set temperature of the thermosensor 6 is set to a predetermined temperature t1, and the contact of the rice cooking relay 14 is turned on to turn on the rice cooking heater 3. The electricity is started and the food to be cooked is preheated for a certain period of time TI. The temperature setting of the thermosensor 6 and the determination of whether the set temperature has been reached are performed as follows.The temperature detected by the thermosensor 6 is converted into a digital signal by digital-to-analog conversion, and is read into the CPU 19. Therefore, the digital signal is compared with the set temperature stored in the ROM 21, and a match or mismatch is determined.

The rice cooking heater 3 is continuously energized until the temperature of the thermosensor 6 that detects the temperature of the food reaches a predetermined temperature tl. However, if the temperature of the thermosensor 6 does not reach the predetermined temperature even after the above T+ time has elapsed, 11
As time passes, the process moves to the next stage, the secondary preheating step.

,p LC,,T When the temperature of the thermosensor 6 in the oil reaches the predetermined temperature t1 at 1 hour, the remaining υ time is
Control is performed to maintain the predetermined temperature 11 as much as possible by switching to intermittent control of ON-MAX for 10-odd seconds (for example, 15 seconds) and OFF-Fix for several seconds (for example, 5 seconds). This intermittent control will be explained.

Now, if the temperature of the thermosensor 6 reaches the predetermined temperature tl due to continuous energization to the rice cooking heater 3 and the energization to the rice cooking heater 3 is stopped, the temperature determination means B in the CPU 19 will stop the energization to the rice cooking heater 3. When 5 seconds have passed, it is determined whether the temperature of the thermosensor 6 is higher than a predetermined temperature ti, and if it is, the power supply to the rice cooking heater 3 is continued to be stopped, and after another 5 seconds, the temperature of the thermosensor 6 is determined. Make a judgment. Conversely, if the temperature of the thermosensor 6 is lower than the predetermined temperature 1°, the power supply to the rice cooking heater 3 is restarted, and when the temperature of the thermosensor 6 reaches the predetermined temperature tl, the power supply to the rice cooking heater 3 is stopped again. After 5 seconds have elapsed since the energization was stopped, the temperature of the rotational thermosensor 6 is determined. Even if the rice cooking heater 3 is continuously energized for 15 seconds, if the temperature of the thermosensor 6 does not reach the predetermined temperature t1, the power supply to the rice cooking heater 3 is stopped after 15 seconds have passed, and after 5 seconds have elapsed, The temperature of the rotational thermosensor 6 is determined, and if necessary, the rice cooking heater 3 is energized.

As described above, if the temperature of the thermosensor 6 reaches the predetermined temperature tx within 71 hours, the ON-MAX for 15 seconds,
It performs intermittent control of 0FF-Fix for 5 seconds, and an example of the control state is shown in FIG. Note that the above-mentioned time of 15 seconds or 5 seconds is not particularly limited, and may be determined at any time depending on the size of the rice cooker, the size and structure of the rice cooking heater, etc.

Therefore, such a second heat process is aimed at correcting the temperature of the food to be cooked with respect to the water temperature and air temperature at the beginning of rice cooking, and is suitable for cases where the water temperature at the beginning of rice cooking is low or the air temperature 2 is low. This is to ensure that the temperature rise of the food to be cooked can keep up with the control mode described below.The reason for incorporating the intermittent control of 15 seconds ON = MAX and 5 seconds 0FF-Fix is the following two steps. This will be explained in detail in the next preheating step.

In the secondary preheating process, the predetermined temperature t'l is
The temperature of the food that has been raised to
is applied to raise the temperature to t2, and the above-mentioned 15 seconds ON-MAX, 5 seconds 0FF-Fix are
At the same time, the set temperature of the thermosensor 6 is increased by, for example, 2° C. every time a certain period of time, for example, 52 seconds elapses.

Now, when the -second heating process is completed and the process proceeds to the secondary preheating process, the set temperature of the thermosensor 6 is set to (tl + 2°C), and the temperature interval time T3 is set to 52 seconds. Secondary preheating of the food to be cooked is started by controlling power supply to the rice cooking heater 3 using an intermittent control method of ON-MAX for seconds and OFF-Fix for 5 seconds. Then, every time 52 seconds elapse, the set temperature of one thermosensor 6 is increased by 2 degrees Celsius, and eventually, after a certain period of time T2 has passed from the start of secondary preheating, the set temperature of the thermosensor 6 reaches the t2 temperature. Once the flag area C of the RAM 22 is designated, the process moves to the next capacity determination process.

This "secondary preheating process" promotes water absorption of the rice, and makes the temperature of the cooked food constant and uniform when moving to the next capacity determination process, no matter what the rice cooking capacity. The purpose of this is to enable more accurate capacity determination.Therefore, it is desirable to set the t2 temperature to around 60°C, and it is desirable to set the T2 time to about 8 to 10 minutes. be.

Here, the reason for adopting the intermittent control method of 15 seconds ON-MAX and 5 seconds 0FF-Fix will be described. In the case where the set temperature of the thermosensor 6 is gradually increased as in the present invention, if the rice cooking heater 3 is continuously energized for too long, the temperature of the thermosensor after stopping the energization to the rice cooking heater 3 may change. The overshoot of is shown in Figure 10 (
In cases where the size becomes too large and ideal control is no longer possible as in a), by introducing an intermittent control method, the 10th
As shown in Figure (b), the overshoot can be suppressed to a small level, and thereby the temperature of the thermosensor 6 does not deviate greatly from the set temperature, and good control can be performed. In addition, each time the power supply to the three rice cooker heaters is stopped, the power supply is stopped for at least a certain period of time (5 seconds), so during this time, it is possible to equalize the temperature of the food to be cooked, especially in the areas near and far from the rice cooker heater 3. The temperature difference can be reduced significantly compared to the case where the rice cooking heater 3 is continuously energized.Furthermore, the temperature difference between the thermosensor 6 and the food to be cooked is originally different due to the difference in heat capacity, etc. Although there is a slight time lag between the two and a temperature difference, the time difference is absorbed during the energization stop state in the intermittent control as described above, and the temperature of the two approaches and the difference is reduced. Therefore, better control with higher precision is performed.

The preheating control means for executing the primary and secondary preheating steps as described above is the rice cooking/timer start control key 13.
, a storage means A in the CPU 19, temperature determination means B1, control program contents in the ROM 21 corresponding to the contents stored in the storage means A, a thermosensor 6, a rice cooking relay 14, and the like.

○ Capacity judgment process When moving from the secondary preheating process to the capacity judgment process, RAM2
Based on the designation of the flag area C in No. 2, the fourth
Control is performed as shown in the flowchart shown in FIG.

In this capacity determination step, the temperature of the cooked food that has risen to temperature t2 is raised to temperature t3 over a certain period of time T4. While executing the intermittent control method of 0FF-Fix for 5 seconds, the set temperature of the thermosensor 6 is increased by, for example, 2 degrees Celsius every time a certain period of time, for example 40 seconds, as shown in Fig. 12, and the rice cooking heater is 3 is stored in the rice cooking capacity determination data storage area in the RAM 22 and integrated.

Now, proceeding to the capacity determination step, at the same time as setting the set temperature of the thermosensor 6 to (t2+2℃), the temperature interval time T5 is set to 40 seconds, ON-MAX is set for 15 seconds,
! Execute the intermittent control method of 0FF-Fix for 5 seconds. During this time, if the temperature of the thermosensor 6 is lower than the set temperature, the rice cooking heater 3 is energized for a maximum of 15 seconds to heat and raise the temperature of the food, while adding up the energization time to the rice cooking heater 3. Go. In this way, every time 40 seconds elapse, the set temperature of the thermosensor 6 is increased by 2 degrees Celsius, and the energization time to the rice cooking heater 3 is integrated, until T4 hours have elapsed since the start of the capacity determination process. When the set temperature of the thermosensor 6 reaches the t3 temperature and the flag area of the RAM 22 is designated, the rice cooking capacity is determined based on the cumulative energization time of the rice cooking heater 3. Incidentally, in the capacity determination step, the timing of energizing the rice cooking heater with respect to changes in setting and measured temperature is illustrated in FIG. 13.

In the capacity determination step, the t3 temperature is not particularly limited, but is preferably determined within the range of 85°C to 90°C. That is, in the structure of the rice cooker as shown in the first diagram, from t2 (around 60°C) to t3 (85 to 90°C)
The temperature range is the temperature range where the change in the rice cooking heater energization time with respect to the size of the rice cooking capacity is the most severe, and is the most preferable as the collection period for the rice cooking capacity determination data.

Next, determination of rice cooking capacity will be explained. The rice cooking capacity is determined by reading out the rice cooking capacity determination program stored in the ROM 21 in advance based on the designation of the flag area, and calculating the rice cooking capacity as shown in the flowchart shown in FIG. Determine the heating sequence during the raising process. This heating sequence is a heating power adjustment, and specifically, a so-called duty control is adopted, which is a method of adjusting the time during which the rice cooking heater 3 is energized within a certain period (for example, 64 seconds). The heating duty for the next cooking process determined as a result of the capacity determination is determined by applying a heater voltage suitable for the rice cooking capacity, but in order to completely gelatinize the rice, the rice should be kept at 90℃ or above for 20 minutes or more. The conditions are to keep the temperature constant, to eliminate boiling, and to keep the cooking time constant.

In addition, the rice cooking capacity is determined by taking into consideration the accumulated time of energizing the rice heater, the power supply voltage when the rice heater is energized, and whether the rice is cooked by a timer or by instant cooking, thereby making the determination more accurate. That is, as can be seen from the experimental data shown in FIG. 15, even if the cumulative energization time of the rice cooking heater is the same, the rice cooking capacity determination result does not vary significantly depending on the level of the N source voltage and whether rice is cooked on a timer. For example, when the cumulative time is 240 seconds, the rice cooking capacity determination value varies over a range of 3 to 8 cups.

For this reason, it is necessary to carry out program processing based on the above three conditions in order to be able to accurately determine the capacity, and the mechanism is shown in the flowchart of FIG. 14. still,
The above-mentioned timer rice cooking will be explained in detail later, but in the case of timer rice cooking, the rice is immersed in water from the time the time is set until the rice cooking starts, and the rice has absorbed some water when the rice cooking starts, so the rice can be cooked immediately. The amount of water absorbed by rice is different compared to rice, and this causes a difference in the cumulative energization time of the rice heater even if the rice cooking capacity is the same.As a result, by including the distinction between timer cooking and instant cooking as a condition when determining the rice cooking capacity. , the amount of water absorbed by rice is corrected.

In FIG. 14, the rice cooking capacity is determined at the end of the capacity determination process. First, by reading out the timer rice cooking determination contents temporarily stored in the RAM 22, it is determined whether the rice cooking currently being executed is timer cooking or instant rice cooking. still,
The time setting means E reads whether or not the time has been set using the timer set key before operating the rice cooking/timer start key, and temporarily stores the information in the RAM 22 in advance.

After this determination is completed, the value of the current power supply voltage is compared with the value stored in the ROM 21 to determine whether the power supply voltage is in the low voltage, standard voltage, or high voltage range. After that, the rice cooking capacity is determined as shown in the flowchart of FIG. 16 based on the rice cooking heater energization cumulative time. The rice cooking capacity is divided into four categories according to timer rice cooking and instant rice cooking, and the state of the power supply voltage for each type of rice cooking, and each category is further divided into 10 stages according to the specific time width of the rice cooking heater energization time. A heating duty is set for each capacity as described below, and the programmed contents are stored in advance in R<)M21.

After determining the power supply voltage, the rice cooking heater energization cumulative time TR temporarily stored in the RAM 22 is read out, and
By reading the rice cooking capacity determination program in the ROM 21, the rice cooking capacity is determined as shown in the flowchart shown in FIG.
(The rice cooking capacity when the relationship O is reached is determined, and the heating duty is determined based on this determined capacity Go. In this way, when 14 hours have passed and the flag area F of the RAM 22 is specified, Move on to the next stage of cooking process.

As described above, in the capacity determination process, the set temperature of the thermosensor 6 is increased by 2°C every 75 hours, and the temperature is turned on for 15 seconds.
By executing the intermittent control method of MAX, 5 seconds 0FF-F'ix, the temperature of the food to be cooked is raised from t2 temperature to t3 temperature over 14 hours, and the time during which electricity is applied to the rice cooking heater 3 is accumulated. Based on this cumulative energization time, the rice cooking capacity is determined taking into consideration the power supply voltage state and whether timer rice cooking or instant rice cooking is used, and the heating duty in the cooking process is determined.
Determine.

As can be seen from Figure 14, the number of determinations for rice cooking capacity is 60 types in 6 categories and 10 stages, all with different heating duties, and these heating duties are as follows:
■It is based on the formula.

The above formula 0 is a formula that calculates the heating power until boiling, and the formula 0 is a formula that calculates the heating power after boiling. Here, by keeping the cooking time (■10■) constant, the heating power (■10■) can be determined from the formula 00. Then, a heater of a size that has the maximum value of the heating power (■ + ■) obtained in this way is adopted as a rice cooking heater, and when this heater is controlled by Denny Tea, it is possible to adjust the size to suit each capacity. Produces heating power.

In this duty control, the time T6 for energizing the rice cooking heater 3 within a certain period can be calculated by the following equation (0) (see FIG. 17).

Although the cycle of the duty control is set to 64 seconds, this is a value set in consideration of the lifespan of the rice cooking relay 14, and is not particularly limited to this value.

○ Cooking process After transitioning to the cooking process, the heating program and program contents corresponding to the heating duty determined in the first capacity determination process based on the designation in the 7 rasog area F of the RAM 22 are stored in the ROM.
21, the rice cooking heater 3 is controlled on a duty cycle to raise the temperature of the food to be cooked up to temperature t4 (approximately 124°C), and when the temperature exceeds t4, the thermosensor 6
When the error is detected, the process is ended, and the flag area G of the RAM 22 is designated to proceed to the next double-cooking/uncoating process (see chart 70 in FIG. 18).

This cooking process differs from the previous steps in that it ends when the thermosensor 6 detects that the temperature reaches the t4 temperature, so it includes an element of temporal instability.
By determining the rice cooking capacity and determining the heating duty suitable for it, and executing the duty control of the rice cooking heater in the relevant process based on this, the variation in the time T7 required for the rice cooking process is extremely small. The time is approximately constant.

〇 Double-cooking/uneven process In the double-cooking/uneven process, the burn setting contents temporarily stored in the RAM 22 are read based on the designation of the flag area G of the RAM 22, and the contents of the ROM 21 corresponding to the setting contents are read out. By reading out the contents of the control program, control is performed as shown in the flowchart shown in FIG. 19, and after a certain period of time Ts (for example, 12 minutes), the flag area H of the KRAM 22 is designated and the process is moved to the warming process.

First, to adjust or set the thorns, press the control key 13 for adjusting the thorns to select "Standard" → "Light" → "Standard" → "
It can be set repeatedly in the following order: "Dark" → "Standard" → "Light" →... The burnt degree determining means (■) measures the number of times the control key 13 is pressed, and (setting contents) are temporarily stored in the RAM 22. Then, when moving to the double-cooking/unevening process, the burn setting contents are read out from the RAM 22, and the control program contents in the ROM 21 corresponding to these contents are read out. Control. In addition, each figure of FIG. 20 is a figure which shows the relationship between the temperature change of the thermosensor and the energization state of the rice cooking heater in the same process, and (a) l
When dr light J is set, (b) is when set to "Standard", (c) is when set to "
Indicates when “Dark” is set.

If it is currently set to "Light", it will detect that the temperature of the thermosensor 6 has become less than the t4 temperature (124℃) and start counting the time, and when one minute has passed, the rice cooker heater 3 will be activated for a short time. Electricity is applied (for 5 seconds) to add thorns to the food to be cooked, that is, rice, and then electricity to the rice cooking heater 3 is stopped.

When set to "Standard", it detects that the temperature of the thermosensor 6 has become less than the t4 temperature and starts counting the time, and when one minute has passed, the rice cooking heater 3 is energized and the temperature of the thermosensor 6 is increased. The food to be cooked is heated until the temperature reaches t4, and when the temperature reaches t4, the power supply to the rice cooking heater 3 is stopped and the rice cooking heater 3 is kept in a stopped state from then on.

When set to "Dark", the rice cooking heater 3 is energized one minute after the temperature of the thermosensor 6 falls below the t4 temperature to raise it again to the t4 temperature, similar to the above "Standard". But then again, thermo sensor 6
Counts for 1 minute from when the temperature of the thermosensor 6 becomes less than the t4 temperature, and after 1 minute has elapsed, the rice cooker heater 3 is energized and the food is heated again until the temperature of the thermosensor 6 reaches the t4 temperature, after which the energization is turned off. Stop.

Thus, the double-cooking/shading process 8 ends after 78 hours have elapsed from the start, and the flag area H of the RAM 22 is designated, and the process moves to the warming process.

This double-cooking/smoothing process finishes the rice by draining the cooked rice and adjusting the charring, and by the end of this process, the rice is thoroughly cooked and the rice is ready to eat. Obtained 0. Note that the setting of the thorns can be done arbitrarily before moving to the double-cooking/shading process, and subsequent setting operations will be invalid.

As described above, the rice cooking control means includes a preheating control means, each flag area of the RAM 22, program contents in the ROM 21 corresponding to each area, and an electronic timer.

The capacity of the food to be cooked is determined based on the signal from the thermosensor 6, and the power supply to the rice cooking heater 3 is controlled based on the determination result. It is configured to complete the rice cooking in a substantially constant time from the start of rice cooking (-start of second heat), and finish the rice after a certain uneven time after the completion of cooking.00 Warming process When moving to the warming process. , the heat retention relay 16 is turned on, and this ON state continues until the cancel control key 13 is pressed. Control in the heat retention step is performed by a heat retention thermal reed switch 7 that detects changes in the temperature of the food, and as shown in FIG. 21, the thermal reed switch 7 is turned on.

When turned off, the power supply to the rice cooking heater 3 and the warming heater 5 is controlled to keep the rice to be cooked warm.

The temperature setting of the thermal reed switch 7 is set to a temperature suitable for keeping rice warm, for example, 70°C.

Next, one means of the rice finishing timer will be explained.

This timer means is for executing the timer rice cooking, and is configured to arbitrarily set a finishing time and cause the rice cooking control means to start rice cooking a certain time before the end of the set time.

The rice finishing timer means includes a time setting means E in the CPU 19, a rice cooking start determination means including the program contents specified by the 7 racks, a display control means including the program contents specified by the flag, and a time setting program contents in the ROM 21. , electronic timer 20, RAM 22, time display element (time display section lO), timer set key 1
2 and a rice cooking/timer start control key 13, which will be explained in order below.

First, time setting is performed as shown in chart 70 in FIG. 22 by reading the input state of the timer set key 12 with the time setting means E and reading out the time setting program contents and display program contents from the ROM 21. .

In FIG. 22, when the time key of the timer set key 12 is pressed, while the key is pressed, the time data is counted up by one hour at a constant cycle, and the time display elements 1'l:l, The time is displayed in the following manner as 2.3..., and the time is set up to 12 hours. Next, when you press the minute key, the display on the hour display element switches to minute display, and while the minute key is pressed, the minute data counts up in 10-minute increments at a constant cycle, and the time display element displays Yo, 910, 20, 3
0... and so on, and the minutes are displayed.Finally, the hours and minutes are set by pressing the button, and the timer enters the actual operating state.

The time display element is normally in the time display state and switches to minute display only when the minute key is pressed.

If the key is not operated for a certain period of time (for example, 4 seconds) before pressing the rice cooking/timer start control key 13, the display changes to timer start standby mode (
For example, the mode is switched to (for example, hours and minutes are displayed alternately), and when the mode is continued for a certain period of time (for example, 3 minutes), the mode is switched to a cancel mode (for example, 88 is displayed blinking).

In the timer actual operation state, the display control is performed by counting down the time data from the set time and reading out the contents of the display program, as shown in the flowchart shown in FIG. That is, as time passes, the time display by the time display element counts down in units of one hour to display the remaining time until the end of the rice is finished, and when the remaining time is less than one hour, the time display starts. The time display by the element is switched to the Co (abbreviation of 'C00K) display to indicate that the rice cooking operation has started from rice cooking standby.

Then, at the same time that the temperature of the thermosensor 6 reaches t4m degrees and shifts from the cooking process to the double-cooking/uniforming process, the C0 display by the time display element is switched to the minute display,
Displays the execution time Ts, that is 12 minutes, for the double-cooking and unevenness process, and then counts down in 1-minute increments to display the remaining 9 hours until the rice is finished. This coincides with the end of the boiling and shading process.

When moving to the warming process, the time data is counted up, the elapsed warming time is displayed by the time display element, and 1
Count up by the hour.

On the other hand, the determination to start cooking rice is made by determining whether or not the remaining time until the finishing time reaches 9 hours (a time shorter than the To waiting time of 1 hour) is reached, and when the To waiting time is reached, the rice cooking is started by the rice cooking control means. let The above To waiting time, T+, T2. T44'
Determined based on the total total time of 7Ts. In making this decision, there is no problem since each time T+ -T2- T4 and Ts is a constant time, but 77 hours includes an unstable element as explained in the previous cooking process. It is necessary to consider how much to expect. However, as explained above, although there is some variation in 77 hours, it is a nearly constant time, so if you determine the To waiting time based on experimental data and include each time of T + T2 T4 Ts, To waiting time: Although there is a difference in the time required from the start of rice cooking until the rice is finished, the difference is kept extremely small when viewed from the overall To time.

In addition, in the time display section 10, from Co display to double cooking,
The time from the start of the unevenness process to the switching to minute display is calculated to be 48 minutes, but in reality it does not necessarily match because the unstable time T7 is included. However, the time zone including T7 is displayed as C0 and no time is displayed, and the time difference is extremely small. Furthermore, the end of the double cooking/smoothing process coincides with the O display, so users can rely on it. It is possible to almost accurately obtain rice that is most ready to eat at a set desired time without impairing its quality.

Here, rice cooking using a rice finishing timer means, ie, timer rice cooking, will be briefly explained with reference to the flowchart shown in FIG.

If you want to finish 4 cups of rice after 12 hours under standard voltage and add thorns to the standard degree, first wash 4 cups of rice, place it in the inner pot 4, and add water to the specified water level accurately. After filling, the inner pot 4 is placed inside the outer pot 2 and the lid is closed. Next, insert the power plug into the outlet and turn on the power.
1 by pressing the time key of timer set key 12.
The timer is set to 2 hours, and then the rice cooking/timer start control key 13 is pressed to put the timer into actual operation.

Then, as time passes, the remaining time appears on the time display section 10.
It is displayed in hour increments, and when 11 hours have passed and the remaining 9 hours become less than 1 hour, the CO
is displayed, indicating that the rice cooking has entered the standby state.

Furthermore, when time passes and the remaining time becomes To waiting time,
When rice cooking starts, the primary heating process is executed, and when T+waiting time elapses, the process moves to the secondary preheating process, and when 72 hours have elapsed, the process moves to the capacity determination process. ° In this capacity determination process, the set temperature is increased by 2℃ every fixed time T5, and then an intermittent control method of 15 seconds ON-MAX and 5 seconds 0FF-Fix is executed. The energization time of the rice cooking heater 3 is accumulated, and this accumulated time is collected as rice cooking capacity determination data. Then, when 14 hours have passed, the rice cooking capacity is determined based on the power supply voltage, timer rice cooking/immediate rice cooking, and the rice cooking heater's cumulative energization time, the corresponding heating duty is determined, and the next stage of cooking is started. Move on to the process. In addition, in the case of this rice cooking example, (
2-4), and the heating duty corresponding to the region (2-4) is selected.

When moving to the cooking step, the rice is cooked by heating at the previously determined heating duty, and the rice is cooked together.

When the temperature of the thermosensor 6 reaches the T4 temperature and the rice is cooked, the process moves on to the double-cooking/uniforming process, and at the same time, the time T8 time, that is, 12 minutes, is displayed on the time display section 10.
Incidentally, before entering the double-cooking/unevening process, the degree of thorniness is set to "standard" by operating the control key 13 for scorching adjustment.

In the double-cooking and uneven cooking process, when the rice cooking heater 3 is controlled as shown in FIG. When the display becomes 0, the process ends and the process moves to the heat retention process. Therefore, this time is about 12 hours after pressing the rice cooking/timer start control key 13.
When rice that is ready to eat is obtained after being sufficiently uniformed, the minutes are displayed in the above-mentioned double-cooking/uniforming process, not only when rice is cooked on a timer but also when rice is immediately cooked.

In the above embodiment, the heater control method of the present invention is executed in the secondary preheating process and the capacity determination process, but it is not limited to these processes, but can be executed in other processes if necessary.

In addition, the present invention is not limited only to the embodiments described above and shown in the drawings, and it goes without saying that the present invention can be practiced with appropriate changes in temperature, time, etc., without departing from the scope of the invention.

(Effects) As described above, in the present invention, by setting a limit on the continuous energization time to the heater, the overshoot of the thermosensor temperature with respect to the set temperature is suppressed to a small value, and the thermosensor temperature is prevented from deviating greatly from the set temperature. In addition, by keeping the power supply to the heater stopped for at least a certain period of time regardless of the temperature, it is possible to absorb the time lag between the temperature rise of the thermosensor and the temperature rise of the food being cooked, and also to maintain a uniform temperature of the food. The temperature difference J\ between the thermosensor temperature and the temperature of the food to be cooked is also measured, and the set temperature can be increased successively at regular intervals, making it possible to perform highly accurate control.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the schematic structure of a rice cooker that implements the heater control method of the present invention, Fig. 2 is a front view of the operation panel section of the above, Fig. 3 is a circuit diagram of the heater as above, and Fig. 4 is a control of the same as above. A block diagram of the entire circuit, Fig. 5 is the main 70-chart of the same as above, Fig. 6 is a curve diagram showing the relationship between the time elapsed from the start of rice cooking to keeping it warm and the temperature change of the thermosensor, Figs. 7 and 8. 70-chart of the same as above-next and secondary preheating process, Fig. 9 is an explanatory diagram showing the intermittent control state of the rice-cooking heater as above, and Figs. FIG. 11 is a flowchart for collecting judgment data in the capacity determination process as described above, FIG. 12 is a diagram showing changes in set temperature in the capacity determination process as described above, and FIG. A diagram showing the timing of energizing the rice cooking heater with respect to the measured temperature, FIG. 14 is a flowchart for determining the rice cooking capacity in the capacity determination process same as above, and FIG. 15 is an experiment showing the relationship between the cumulative time of energization of the rice cooking heater and the rice cooking capacity in the capacity determination process same as the above. Data, Fig. 16 is the rice cooking capacity determination diagram as above, Fig. 17 is an explanatory diagram showing the control state of the rice cooking heater in the cooking process as above, Fig. 18 is a flowchart of the cooking process as above, Fig. 19 is as above. Flowchart of the double-cooking/mixing process, Figures 20 (&) to (c) are diagrams showing the relationship between the temperature change of the thermosensor and the electricity supply to the rice-cooking heater in the double-cooking/mixing process. The figure is an explanatory diagram showing the control state of the heat-retaining heater in the same heat-retaining process, and the second
FIG. 2 is a timer setting flowchart same as above, and FIG. 23 is a time display flowchart same as above. 3: Rice cooking heater, 4: Inner pot, 6: Thermosensor, 18
Two microcomputers. Agent Patent Attorney Aihiko Fukushi (and 2 others) Figure 3 Figure 4 Figure 7 Figure 8* Figure 10 Figure 11 Figure 15! 7 Figure 22 Figure 23 Procedural Amendment 1, Indication of Case Patent Application 1982-128118 2, Name of Invention Method for controlling rice cooker shutter 3, Person making the amendment Relationship to the case Patent Applicant Address Address: 22-22 Nagaike-cho, Abeno-ku, Osaka 545 Name/(50,4) Sharp Corporation 4 Address of agent: 22-22 Nagaike-cho, Abeno-ku, Osaka 545 Owner 6 Subject to amendment 1) Specification Column 7 of Detailed Description of the Invention, Contents of Amendment 1) Specification @ page 9, lines 12 to 14 [More

Claims (1)

[Claims] 1. It has a pot that houses the food to be cooked, a heater that heats the pot, and a thermosensor that detects changes in the temperature of the food through the pot, and increases the set temperature one after another at regular intervals. , in a rice cooker that heats and raises the temperature of food by controlling energization to the heater based on a set temperature and the temperature of a thermosensor, a limit is placed on the continuous energization time to the heater, and the energization of the heater is stopped. A rice cooker in which the energization of the heater is controlled intermittently based on the set temperature and the temperature of the thermosensor, assuming the conditions for continuous energization and cessation of energization of these heaters so as to maintain the energization for at least a certain period of time regardless of the temperature. heater control method.