JPS6335244B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention automatically controls the rice cooking process and the warming process by processing the pot temperature detection signal using a data processing circuit. Regarding the rice cooker control device.

Conventionally, electric rice cookers have been devised that detect the pot temperature with a thermistor, process the detection signal with a data processing circuit such as a microcomputer, and automatically control the rice cooking process and the subsequent warming process. be. Compared to a simple structure in which the electric heater for rice cooking is turned off by a temperature switch that responds to the cooking temperature, this method can create a variety of temperature states, so it can be used not only for regular rice cooking. , "kayu-daki" becomes possible, etc.
It is expected that it will be possible to obtain many ways of cooking rice. For example, in a device configured to perform normal rice cooking and keeping warm, the rice cooking mode that automatically executes everything from cooking to keeping the rice warm, and the keeping warm mode that only executes keeping warm can be selected using a selection operation member. can be considered as a natural conclusion. By the way, as a general property of data processing circuits constituted by electronic circuits, if a power failure occurs during execution of a certain process, the circuit returns to its initial state. For this reason, if we consider a case where a power outage occurs during operation when the rice cooking mode is selected using the selection operation member and the power is then restored, if a power outage occurs during the rice cooking process, rice cooking will start again when the power is restored. In some cases, the cooked rice may be unsatisfactory. Furthermore, if a power outage occurs during the warming process after the rice cooking process, the rice cooking process will start when the power is restored, resulting in the problem of burning rice. To prevent this, if a power outage occurs after normal operation has started when the power is turned on, the power to the rice cooker will not be turned on again even after the power is restored. To,
For example, the selection operation member may be made non-retentive, but
In this case, it becomes impossible to use an external timer for starting rice cooking after a predetermined time. In addition, power outages that cause inconveniences such as those mentioned above are not limited to actual power outages; for example, when rice cooking mode is selected, the power plug is pulled out from the outlet while the rice cooker is being kept warm, the rice cooker is moved to another room, and the power plug is plugged back in. This phenomenon also occurs when the rice cooker is plugged into an outlet, so the rice cooker is subject to various restrictions when used.

The present invention was made in view of the above circumstances, and its purpose is to detect the temperature of a pot and process the temperature signal by a data processing circuit to automatically control the process from rice cooking to keeping warm. If a power outage occurs during a power outage and the power is restored again, the rice cooking status at the time of the power outage is determined, and based on the determination result, either cooking or keeping the rice warm is determined. To provide a control device for a rice cooker that can reliably prevent improper process execution.

An embodiment of the present invention will be described below based on the drawings. First, in FIG. 1, 1 is a substantially cylindrical outer case, 2 is a bottom frame fitted to the lower part of the outer case 1,
3 is an inner case disposed within the outer case 1; 4 is a heat insulating material disposed between the outer case 1 and the inner case 3;
5 is a pot detachably disposed within the inner case 3; 6;
1 is an electric heater for cooking rice arranged at the inner bottom of the inner case 3; 7 is an electric heater for keeping warm wrapped around the upper outer periphery of the inner case 3; 8 is a lid rotatably supported on the outer case 1; Reference numeral 9 denotes a locking device that holds the lid 8 in a locked state. 10 is a heat transfer case provided so as to be pressed against the outer bottom of the pot 5 by a spring 10a;
A thermistor 11 with a negative characteristic as a temperature detecting element is disposed in the inside thereof in terms of thermal conduction. Although not shown in FIG. 1, this rice cooker is equipped with an operation panel 12 as shown in FIG. '' position, and display lamps 14 and 15 for displaying selected positions other than ``off'' are provided. In the control device shown in FIG. 3, a bidirectional three-terminal thyristor (hereinafter simply referred to as a thyristor) 16 is a switching means, and a series circuit between this and the electric heater 6 for rice cooking receives power from a power plug 17. It is connected to the. Further, the heat-retaining electric heater 7 is connected in parallel with the thyristor 16, so that when the thyristor 16 is turned off, the rice-cooking electric heater 6 and the heat-retaining electric heater 7 are connected.
are energized in series, each of which generates heat with a relatively small heat generation capacity to perform a heat-retaining operation, and when the thyristor 16 is turned on, only the rice cooking electric heater 6 is energized and generates heat with a relatively large heat generation capacity. A rice cooking operation is performed. 18 is a data processing circuit that controls the thyristor 16 to perform the rice cooking operation and the warming operation as described above;
1 and a mode designation signal S2 from a mode selection section 20. When the selection operation member 13 is set to the "rice cooking" position, this mode selection section 20 sets the content of the mode designation signal S2 to "rice cooking mode",
The data processing circuit 18 receiving the mode designation signal S2 having this content receives the temperature signal S1 from the temperature detection section 19.
to automatically control the rice cooking process and the subsequent warming process, and also to set the selection operation member 13 to "keep warm".
When set to the temperature signal S1, the mode selection unit 20 sets the mode designation signal S2 to the "warm-keeping mode", and the data processing circuit 18 thereby performs the heat-keeping operation based on the temperature signal S1. FIG. 4 shows a data processing circuit 18 that controls general operations as described above.
Among them, a configuration specifically designed to deal with power outages is shown. Although the data processing circuit 18 can be configured by a so-called microcomputer including the configuration shown in FIG. 4, for ease of understanding, each of the configurations in FIG. 4 is configured as hardware using an electronic circuit. It is shown by the functional blocks that can be used. In addition, in Figure 5, the pot temperature T is plotted on the vertical axis and the time t is plotted on the horizontal axis ( _t0 corresponds to the time when the power is first turned on or the time when the power is restored after a power outage). Temperature characteristic curves 21, 22, and 23 in various states regarding rice cooking in No. 5 are shown.
In addition, in Figure 5, TH is 70℃, THL is 60℃,
THH is 80℃, and around 60-70℃ is the heat retention temperature for this rice cooker.
In this embodiment, 60°C is treated as a set value, and 80°C is treated as a specific reference value. The characteristic curve 21 shows the normal rice cooking state of the pot 5 containing rice and water from the power-on time t ₀ , that is, the temperature load state of the pot 5, and the characteristic curve 22 shows the temperature decreasing for a certain period of time from the power-on time t ₀ . Indicates the temperature load state of the pot 5 that may cause
The characteristic curve 23 shows the temperature load state of the pot 5 in which the temperature rises once from power-on time t ₀ and then falls. The configuration shown in FIG. 4 determines the rice cooking state of the pot 5 during a power outage, that is, the temperature load state, according to the characteristics shown in FIG. 5, and attempts to deal with it when the power is restored. A flowchart illustrating this is shown in FIG.
The configuration shown in FIG. 4 will be explained below along with its function.

(i) Temperature reading function 24 is the power-on detection section, and the power plug 1
7 is plugged into an outlet and the selection operation member 13 is set from the "off" position to the "cooking" position, or when the selection operation member 13 is set to the "cooking" position.
The timer start signal S3 is activated when the power plug 17 is inserted into the outlet at the power supply position, or when the power is turned on and a power failure occurs and the power is restored, in other words, at the power-on time _t0 . is now output. The following description will proceed assuming that the selection operation member 13 is set to the "rice cooking" position. 25 is a timer which starts a timing operation upon receiving the timer start signal S3, and outputs a timing completion signal S4 at _time t ₁ after approximately 30 seconds has elapsed _;
The reading command signal S5 is continuously output for a period of time. This time of 30 seconds corresponds to the initial power-on ta as shown in FIG. 26 is a temperature storage section, which continuously receives the temperature signal S1 of the pan 5 from the temperature detection section 19 while receiving the read command signal S5, that is, during the initial power-on period ta, and stores the respective values every moment. I'm starting to do that.
27 is a temperature reading section, which is a timer 25
It is activated by receiving a timing completion signal S4 from , and serially reads each temperature information S6 stored in the temperature storage section 26 during the initial power-on period ta and supplies it to the first comparison section 28. ing.

(ii) When determining less than 60 degrees Celsius As described above, during the initial power-on period ta, the temperature information S6 of the pot 5 that changes with time is read one after another, and this is determined by the first comparing section 28 to the 60 degrees setting section 29. 60 degree setting signal S7 set to
are compared sequentially. The first comparison section 28 indicates that the temperature of the pot 5 is continuously 60 during the initial power-on period ta.
When it is determined that the temperature is less than 60 degrees Celsius, a less than 60 degrees determination signal S8 is output, and when it is determined that the temperature is 60 degrees Celsius or more even once, a 60 degrees or more determination signal S9 is output as a set value or more determination signal. The fact that the temperature is continuously below 60°C during the initial power-on period ta corresponds to characteristic curve 21 in Fig. 5, and the temperature load on the pot 5 is normal when it is in the state of water and rice. The condition is such that it is safe to cook rice normally, or if time t ₀ is the time when the power is restored after a power outage, the power is cut off before the water temperature reaches 60°C and cooking continues as the power is restored. It means that it is in good condition. In such a case, the above-mentioned less than 60 degree determination signal S8 is generated, and upon receiving this, the rice cooking designating section 30 designates the "rice cooking mode", and thereby the rice cooking process and the warming process are automatically executed. Become so.

(iii) When determining 60℃ or higher: The pot temperature is 60℃ during the initial power-on period ta.
There are two cases in which the temperature exceeds 0.degree. C. as shown by curves 22 and 23 in FIG. 5, and these are distinguished by the sign of the temperature gradient. Now, as described above, when the 60 degree or higher determination signal S9 is output from the first comparison section 28, the gradient calculation section 31 receives this and performs calculation for determining the temperature gradient. This calculation is performed by subtracting the temperature information _S60 detected at time _t0 from the temperature information _S61 detected at time _t1 , and if the result of this subtraction is negative, a negative slope determination signal S10 is output, If positive, positive slope determination signal S1
Outputs 1. The fact that the temperature of the pot 5 may reach 60° C. or higher and the temperature gradient at that time is negative corresponds to the characteristic curve 22 in FIG. If the temperature load on the pot 5 is as shown in the characteristic curve 22, even though the power is turned on, the temperature gradually decreases from the power-on time t ₀ and then rises again. After the power was raised, there was a power outage, which caused the rice cooker to gradually cool down, and even when the power was restored at time t ₀ , the pot 5
There may be a case where the temperature gradient becomes negative due to a time delay in the rise in temperature, or a case where water and rice are put into the pot 5 again before the rice cooker has cooled down after the rice cooking process is completed, and rice cooking is started again. . However, in any of these cases, there should be no problem in continuing the rice cooking, and therefore, when the negative gradient determination signal S10 is generated as described above, it is sent to the rice cooking specifying section 30 to specify the "rice cooking mode". The rice cooking process and subsequent warming process are automatically executed. On the other hand, the positive slope determination signal S
11, the temperature gradient of the pot 5 is positive and corresponds to the characteristic curve 23 in FIG. In this way, when the temperature of the pot 5 increases continuously from 60° C. or more at t ₀ when the power is turned on, there are two cases as follows. The first case is when the temperature rises to 80°C or higher at time t ₁ , and the second case is when the temperature rises to less than 80°C at time t ₁ , as shown in characteristic curve 23. be. The second comparing section 32 makes this determination. Upon receiving the positive slope determination signal S11 from the slope calculation unit 31, the second comparison unit 32 compares the specific reference value signal (value corresponding to 80°C) S12 set in the 80 degree setting unit 33 with the time _t1 . Temperature information S detected by
6 ₁ and if (S6 ₁ <S12), outputs the less than 80 degree determination signal S13, (S6 ₁ >S12)
If the angle is 80 degrees or more, a determination signal S14 is output. In the above, characteristic curve 23 shows that the pot temperature is already above 60℃, around 70℃ when the power is turned on, and even though the temperature rises continuously immediately after that, it does not reach 80℃ for about 30 seconds (ta in the figure). The situation is
When the operation of the main unit has completed the rice cooking process and is in the warming process, this corresponds to a power outage and the power being restored at time t _0. In this case, after the power is restored, the rice cooking operation is not executed, but the warming operation is executed. Should. For this reason, less than 80 degrees judgment signal S1
When 3 is output, this is given to the heat retention designation section 34 to cause it to enter the "warm retention mode." Note that the portion 23a onward in the characteristic curve 23 means that the heating state has been switched to keep warm. On the contrary
When the 80 degrees or higher determination signal S14 is output, the conditions for this output are that the pot temperature is 60 degrees C or higher at the power recovery time _t0 , and after that, the temperature exceeds 80 degrees within a short period of 30 seconds. This is a case where the condition is met that the temperature rises continuously and at a high rate.In this case, it corresponds to a short power outage when the cooking temperature approaches the boiling point, and it will not be possible until the power is restored. You can continue cooking the rice. In such a case, the 80 degree or higher determination signal S14 is outputted and given to the rice cooking designation section 30, thereby designating the "rice cooking mode".

As mentioned above, the present invention can not only prevent the original power outage, but also
During a temporary power outage that involves pulling out the power plug and then plugging it back in, the cooking status of the pot at the time of the power outage is determined based on the temperature gradient of the pot temperature during a certain short period of time when the power is restored, that is, at the beginning of the power on. This makes it possible to determine whether to start the process from cooking rice or from keeping warm when the power is restored, so it is possible to reliably prevent incorrect process execution when the power is restored. Therefore, it is possible to provide a control device for a rice cooker that eliminates the problem of temporary power cutoff, which is a problem peculiar to a rice cooking control section that is implemented as a microcomputer.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a vertical side view, Fig. 2 is an enlarged front view of the operation panel, Fig. 3 is an electrical configuration diagram of the control device, and Fig. 4 is a data processing diagram. FIG. 5 is a block diagram of a specific part of the circuit, FIG. 5 is a temperature characteristic diagram, and FIG. 6 is a flowchart of FIG. 4. In the figure, 5 is a pot, 6 is an electric heater for cooking rice, 11 is a thermistor (temperature detection element), 18 is a data processing circuit, 28 is a first comparison section, 31 is a gradient calculation section,
32 is a second comparison section, ta is an initial stage of power-on, S1 is a temperature signal, S9 is a 60 degree or higher determination signal (a set value or higher determination signal), and THH is a specific reference value.

Claims (1)

[Scope of Claims] 1. A temperature detection element that detects the temperature of a pot and obtains a temperature signal, and a data processing circuit that processes the temperature signal to control rice cooking and warming processes, when the power is turned on. a comparison unit that initially determines that the pot temperature exceeds a set value near a warming temperature; and a comparison unit that determines whether the temperature gradient of the pot at the initial power-on is positive or negative when a signal for determining whether or not the pot temperature exceeds the set value is generated from the comparison unit. A control device for a rice cooker, comprising a calculation unit that makes a determination and determines either a rice cooking process or a warming process. 2 A specific reference value of temperature higher than the set value is set, and when the pot temperature at the initial power-on is equal to or higher than the specific reference value, the rice cooking process is executed on the condition that the temperature gradient at the initial power-on is positive. A rice cooker control device according to claim 1.