JPH0441607B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a rice cooker that controls a heating operation for cooking rice based on the temperature of a pot detected by a temperature measuring means. In particular, the present invention relates to a rice cooker with an improved control system.

(Prior art) Conventionally, in a rice cooker, a magnetic shunt steel is attached to the outer bottom of the pot, and a permanent magnet that is attracted and held against a spring is provided on the magnetic shunt steel. When the temperature of the pot detected by the device reaches a preset cooking temperature, the permanent magnet separates from the magnetic shunt steel in response to a sudden decrease in magnetic permeability, and the pot is heated by an interlocking switch that turns off in response to this separation. A configuration has been implemented in which power is cut off to the heater used for the purpose.

In addition, in such rice cookers, conventionally,
By so-called double-cooking, the rice is made alpha-alpha, and excess water is evaporated, resulting in delicious rice. That is, this device uses, for example, a timer device, and this timer device starts a timer operation for a certain period of time in conjunction with the power cutoff of the heater due to the turning off of the interlocking switch, and also switches the timer contacts to a predetermined time. The heater is configured to be turned on for a certain period of time based on timing, and a current conduction path for the heater is formed through the timer contact. Therefore, in such a rice cooker,
When the rice is finished cooking, the heater is turned off, and at a predetermined timing after the power is turned off, the heater is turned on again for a certain period of time to heat the pot, thereby cooking the rice twice.

(Problems to be Solved by the Invention) As in the conventional configuration described above, when the heater power-off timing, in other words, the termination timing of the heating operation for cooking rice, is controlled by magnetic shunt steel, While these properties vary depending on the characteristics of the magnetic steel, permanent magnets, and springs, as well as the state of adhesion between the magnetic shunt steel and the pot, the above characteristics and state of adhesion are uniform for each product. Because it is extremely difficult to
There is a problem in that the timing at which the heating operation ends is inaccurate, and there is a risk that the rice may become scorched or, conversely, the rice may not be alpha-ized sufficiently.

In addition, when adopting a conventional configuration that uses a timer device to perform double cooking, the heating operation for double cooking is independent of the rice cooking conditions such as the amount of rice cooked, the power supply voltage, and the outside temperature. Since the cooking is carried out under the same conditions every time, the heating state (heating temperature) of the pot during double cooking will change according to changes in the above conditions. In particular, when the rice is cooked, the amount of water in the pot is relatively reduced, so if the heating temperature of the pot becomes high, the rice is very likely to burn.

The present invention has been made in view of the above circumstances, and its purpose is to be able to control the end timing of the heating operation for cooking rice extremely accurately, to prevent the rice from burning, and to prevent the rice from burning after the rice is cooked. To provide a rice cooker which can reliably turn rice into alpha by so-called double cooking by reheating a pot and can effectively prevent the rice from burning during the double cooking.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides heating means for heating a pot, temperature measuring means for sensing the temperature of the pot, and sensing from the temperature measuring means. A means for monitoring the output is provided, and the means detects a flat slope of the change in temperature monitored by the pot, and stops the heating means for the pot at a temperature value obtained by adding a predetermined temperature value to the detected temperature value. However, after that, a control means is provided for intermittently reheating the heating means at a temperature lower than the added temperature value.

(Function) When a pot containing rice and water is heated by a heating means, the pot temperature becomes stable after rising to a temperature corresponding to the boiling point temperature of the water. The flat slope continues for a period of time when the water in the pot is convecting. The control means detects the pan temperature D when the change in pan temperature exhibits a flat gradient as described above through the temperature measuring means, and then adjusts the pan temperature to the detected temperature value D to a predetermined temperature. Temperature value with added value
At D′, the heating of the pot by the heating means is stopped.

In other words, the detected temperature value D, which is the reference for when to stop heating the pot, is not a fixed value, but a value that corresponds to the boiling point temperature of the water in the pot, and is dependent on the amount of rice cooked, the power supply voltage, the outside temperature, etc. Since the value corresponds to the rice cooking conditions, it is possible to accurately control when to stop heating the pot.

On the other hand, after the heating of the pot is stopped as described above, the control means intermittently causes the heating device to reheat the pot at a temperature lower than the additional temperature value D', that is, to double-cook the pot. As a result of double-cooking and heating being carried out at a relatively low temperature, the rice may burn even though it is fully cooked and the amount of water in the pot is relatively reduced. will be effectively prevented, and the alpha shift of rice will definitely be promoted.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In Fig. 1, 1 is the main body of the rice cooker consisting of an inner case 2 and an outer case 3, 4 is a lid, 5 is a pot housed in the inner case 2, and 6 is a space between the bottoms of the inner case 2 and the pot 5. This is a heater that is a heating means disposed in the space. Reference numeral 7 denotes a cup-shaped heat-sensitive part that is provided so as to be elastically pressed against the outer bottom of the pot 5. A thermistor 8 serving as a temperature measuring means is enclosed inside the heat-sensitive part 7 by a heat-conductive mold member 9. The thermistor 8 is configured to sense the temperature of the pot 5. Reference numeral 10 denotes a case disposed at the outer bottom of the rice cooker main body 1, and a control circuit 11 serving as a control means whose circuit configuration is shown in FIG. 2 is housed inside the case.

Next, in FIG. 2, reference numeral 12 is an AC power source, and the heater 6 is connected between both terminals of the AC power source via a normally open relay switch 13. 14 is a drive circuit that turns on the relay switch 13 only when signal "1" is input; 15 is a display circuit that lights up a rice cooking indicator lamp (not shown) only when signal "1" is input; 16 is for starting rice cooking. When this start switch 16 is turned on, a signal "1" is output to line _L1 . 17 is a pulse generator, which consists of a shaping circuit 18 that shapes the waveform of the output of the AC power source 12, and a frequency dividing circuit 19 that divides the frequency of the output of this shaping circuit 18. It is configured to output a clock pulse Pc to line _L2 at regular intervals. Now, in the following, the control circuit 11
Although this will be explained in terms of hardware using logic circuits and functional blocks, it goes without saying that the same functions as the control circuit 11 may be obtained by a program on a microcomputer.

That is, first, an overview of each functional block will be explained. Counters 20 and 21 count the pulses input to the clock input terminal CK, and these are cleared when a signal "1" is input to the clear terminal CL. 22 to 31 are comparison parts,
These output a signal "1" when the input value at terminal A is greater than the input value at terminal B, and output a signal "0" in other cases. 32 to 44 are first to first
There are 13 storage units, and the following numerical values are stored in advance. First storage unit 32 serving as a lower limit storage unit... Pot temperature lower limit D ₃₂ [°C] (for example, 90°C), second storage unit 33 serving as an upper limit storage unit
... Pot temperature upper limit D ₃₃ [°C] (for example, 110°C), third and fourth storage units 34, 35 ... measurement time values T ₃₄ , T ₃₅ [seconds] used for measuring the amount of rice cooked (However, T ₃₄ <T ₃₅ ), the fifth, sixth, and seventh storage units 3
6, 37, 38,...Additional temperature value D ₃₆ , D ₃₇ , D ₃₈
[℃] (However, D ₃₆ < D ₃₇ < D ₃₈ ), 8th, 9th,
10 storage units 39, 40, 41... Additional temperature values for double cooking D ₃₉ , D ₄₀ , D ₄₁ [°C] (However, D ₃₉ < D ₄₀ <
D ₄₁ , D ₃₉ < D ₃₆ , D ₄₀ < D ₃₇ , D ₄₁ < D ₃₈ ), 11th,
Twelfth storage unit 42, 43...Measurement temperature values D ₄₂ , D ₄₃ [°C] used for measuring the amount of cooked rice (however,
D ₄₂ <D ₄₃ <D ₃₂ ), 13th storage unit 44...timer time value T ₄₄ [seconds] (in this embodiment, it is set to a value corresponding to, for example, 15 minutes). On the other hand, 45 is This is an A-D converter that receives the resistance value of the thermistor 8 as an input, and this is connected to its terminal φ.
The above input resistance value is digitally converted every time a clock pulse Pc is received from line _L2 . 46 is A-
The temperature converter is a monitoring means that receives the output of the D converter 45 and converts it into a digital temperature value.This temperature converter sends a digital temperature value signal Sd corresponding to the temperature of the pot 5 detected by the thermistor 8 to the line L. Output to ₃ . 47, 48, and 49 are shift registers, which transfer the input value to the terminal A to the terminal B and output the same every time a pulse is input to the terminal φ. Reference numeral 50 denotes a delay circuit, which has a delay time longer than the time required for a signal input to terminal A of the shift register 47 at the front stage to be output from terminal B of the shift register 49 at the last stage.
51 and 52 are subtraction units, which subtract the input value of the terminal B from the input value of the terminal A and output the subtraction result values, respectively. Reference numeral 53 denotes an adder, and 54 an auxiliary adder, which adds the respective input values to the terminals A and B when a pulse is input to the terminal CK, stores the addition result values, and outputs them at the same time. 55 is a rising temperature storage unit, which stores the temperature at terminal D when a pulse is input to terminal CK.
Store the input value for . 56 to 62 are transfer gates, and the signal "1" is applied to their gate terminals.
It exhibits low impedance and allows signals to pass only when it is input. Further, 63 is a monostable multivibrator, 64 to 66 are R-S flip-flops, 67 to 75 are AND circuits, 76 to 78 are OR circuits, and 79 to 85 are NOT circuits.

Next, the specific signal flow shown in FIG. 2 will be described with reference to its effect and the temporal change characteristic diagram of the temperature of the pot 5 shown in FIG. 3. Now, when the lid 4 is closed with a predetermined amount of rice and water stored in the pot 5 and the start switch 16 is turned on, a signal "1" is output to the line _L1 . Then, due to this signal "1", the counters 20 and 21
is cleared, and the R-S flip-flops 64 and 65 are reset to output a signal "0" from their output terminal Q.
The R-S flip-flop 66 is set via the circuit 77 so that the signal "1" from its output terminal Q is applied to the drive circuit 14. Therefore, the relay switch 13 is turned on by the drive circuit 14, and the heater 6 is energized from the AC power source 12.
The rice cooking operation of heating the rice starts.

At this time, the comparator 29 receives the timer time value T ₄₄ from the thirteenth storage unit 44 at its terminal A, and
Moreover, since the initial value (ie, zero) of the counter 21 is input to the terminal B, the signal "1" is outputted, and this signal "1" is applied to one input terminal of the AND circuit 73. The other input terminal of this AND circuit 73 is connected to the R-S flip-flop 65.
Since the signal "0" from the input terminal is inverted to a signal "1" and inputted by the NOT circuit 84, the signal "1" is given from the AND circuit 73 to the display circuit 15, and as a result, the rice cooking operation is performed. In response to the start of the rice cooking operation, the display circuit 15 lights up a rice cooking display lamp (not shown) to indicate that the rice cooking operation is being performed. With the start of such a rice cooking operation, the temperature of the pot 5 rises as shown in FIG. 3, and a temperature value signal Sd corresponding to the temperature is outputted from the temperature converter 46 at a one-second period (the period of the clock pulse Pc). It becomes like this.
Then, in accordance with the temperature rise of the pot 5, first the counter 20, the comparison sections 23, 24, 25, 26, and the third, fourth, eleventh, twelfth storage sections 34, 35,
The cooked rice amount measuring section 86, which includes 42, 43, etc., operates.

In the rice cooking amount measurement section 86, the comparison section 22
is a signal “0” until time t ₁ when the temperature value signal Sd input to the terminal A becomes larger than the measurement temperature value D ₄₂ input from the eleventh storage unit 42 to the terminal B.
, and outputs a signal "1" after time _t1 .
Further, the comparator 23 keeps the signal "1" until time _t2 when the temperature value signal Sd input to the terminal B becomes larger than the measurement temperature value D ₄₃ input from the twelfth storage unit 43 for the terminal A. , and outputs a signal "0" after time _t2 . Therefore, since the signal "1" is outputted from both comparators 22 and 23 and given to the AND circuit 67 only during the period from time t ₁ to _{t 2} , the clock pulse Pc from the line L ₂ is ANDed only during this period.
It passes through the circuit 67 and is applied to the clock input terminal CK of the counter 20, and as a result, the count result value _C20 of the counter 20 indicates that the temperature of the pot 5 rises from the measurement temperature value _D42 to _D43 . The value corresponds to the time required for (the time from time t ₁ to t ₂ ).
The count result value _C20 has a property of increasing or decreasing in proportion to the amount of cooked rice, and the magnitude of the amount of cooked rice is determined based on this count result value _C20 .

That is, the count result value C ₂₀ from the counter 20 is stored in the third and fourth storage units 3 by the comparison units 24 and 25.
4, 35 for measurement time values T ₃₄ , T ₃₅ (T ₃₄ <
T ₃₅ ) respectively. At this time, the comparison section 24
outputs a signal “0” when the count result value C ₂₀ is less than the measurement time value T ₃₄ (in other words, when the amount of rice cooked is relatively “small”), and this signal “0” is output to the NOT circuit 79. The line after being inverted to signal “1” by
Output to L ₄ . Further, the comparison unit 25 outputs a signal “1” when the count result value C ₂₀ exceeds the measurement time value T ₃₅ (in other words, when the amount of cooked rice is relatively “large”).
and outputs this signal "1" to line _L6 . Then, the count result value C ₂₀ is the measurement time value T ₃₅
When the measurement time value T ₃₄ is greater than the following (in other words, when the amount of rice cooked is "medium"), the comparison section 24
The signal “1” is output from the AND circuit 6.
8 and is applied to one input terminal of the comparator 25.
The signal “0” is output from the NOT circuit 8.
After the signal is inverted to “1” by 0, the above AND
The signal is now applied to the other input terminal of the circuit 68, and the AND circuit 68 outputs a signal "1" to the line _L5 .

As described above, the rice cooking amount measurement unit 86
The amount of cooked rice is measured based on the time required for the temperature to rise from the measurement temperature value _D42 to _D43 . At this time, each of the lines L ₄ , L ₅ ,
L ₆ are transfer gates 56 and 59,5 respectively
7, 60, 58, and 61. Therefore, when the amount of cooked rice is "small", the transfer gates 56, 59 are connected to the fifth and eighth storage sections 36, 39. The transfer gates 57 and 60 allow the stored addition temperature value D ₃₆ and double-cooking addition temperature value D ₃₉ to pass, and when the rice cooking amount is "medium", the transfer gates 57 and 60 store the 6th and 9th storage values. Part 37,
The additional temperature value D ₃₇ from 40 and the additional temperature value D ₄₀ for double cooking are allowed to pass, and when the amount of rice cooked is "large", the transfer gates 58 and 61 are set to the 7th,
The addition degree value D ₃₈ and the addition temperature value D ₄₁ for double cooking from the tenth storage units 38 and 40 are allowed to pass through.

After this, the temperature of the pot 5 rises and the temperature value signal Sd
is the pot temperature lower limit value stored in the first storage unit 32
When D exceeds ₃₂ , a temperature value signal is sent to terminal A.
The output of the comparator 26 which receives Sd and receives the pot temperature lower limit value D ₃₂ at terminal B is inverted from the signal "0" to the signal "1". Further, when the temperature of the pot 5 further increases and the temperature value signal Sd exceeds the pot temperature upper limit value D ₃₃ stored in the second storage section 33, the terminal A receives the temperature value signal Sd and the terminal B receives the temperature value signal Sd. The output of the comparator 27, which receives the pot temperature upper limit value _D33 , is inverted from the signal "0" to "1". At this time, the three-input type AND circuit 70 directly receives the output from the comparator 26 at its first input terminal, and receives the output from the comparator 27 at its second input terminal.
It receives the output from the R-S flip-flop 65 through the NOT circuit 81 and the output from the R-S flip-flop 65 to the third input terminal.
The signal is provided to be received via the NOT circuit 82. At this point, the R-S flip-flop 65
Since the signal “0” is output from the comparator 26, the signal “1” is output from the comparator 26, and the comparator 27 outputs a signal “1”.
During the period when the signal “0” is output from the AND circuit 7
All 0 inputs become signal "1". in short
The AND circuit 70 determines that the temperature of the pot 5 is the pot temperature lower limit value D ₃₂
The signal "1" is output only when the pot temperature is between the upper limit value _D33 and the pot temperature upper limit value D33, and this signal "1" is applied to the gate terminal of the transfer gate 62.

Now, when the temperature of the pot 5 exceeds the pot temperature lower limit value D ₃₂ and the transfer gate 62 allows the signal (in this case, the clock pulse Pc) to pass,
comparison unit 28, shift registers 47, 48, 49,
The arithmetic unit 87, which includes the delay circuit 50, the subtraction units 51 and 52, the rising temperature value storage unit 55, etc., comes into operation. In the arithmetic unit 87, the shift register 47 at the front stage transfers the latest temperature value signal Sd input to its terminal A to the terminal B every time the terminal φ receives a clock pulse Pc, and thereby transfers the latest temperature value signal Sd input from the terminal B to the terminal B. The temperature value signal Sd ₁ at the time point seconds ago is output one after another. The next stage shift register 48 is
The temperature value signal Sd ₁ at the time point 1 second before being input to the terminal A is transferred to the terminal B every time the clock pulse Pc is received at the terminal φ, so that the temperature value signal Sd 1 at the time point 2 seconds ago is inputted from the terminal B. Sd ₂ are outputted one after another, and the shift register 49 at the last stage sequentially outputs the temperature value signal Sd ₃ at the point in time three seconds ago from the terminal B in the same way as described above. The subtraction unit 51 subtracts the temperature value signal Sd ₃ at the time point 3 seconds ago from the temperature value signal Sd ₂ at the time point 2 seconds ago, and calculates the subtraction result (i.e., from the time point 3 seconds ago until 1 second has elapsed). ) is applied to the terminal B of the comparing section 28. The subtraction unit 52 subtracts the temperature value signal Sd ₂ at a time point two seconds ago from the temperature value signal Sd 1 at a time point _one second ago, and calculates the subtraction result (i.e., from the time point two seconds ago until 1 second has elapsed). temperature gradient of the pot 5 ) is applied to the terminal A of the comparing section 28 . When the subtraction result by the subtraction unit 52 becomes larger than the subtraction result by the subtraction unit 51, that is, at time t ₃ in FIG.
When the pot 5 exhibits a so-called dry-up state and its temperature gradient starts to rise rapidly from a flat state, the comparator 28 outputs a signal “1” and this signal “1” is sent to the AND circuit 69. Apply to one input terminal. When the clock pulse Pc that has passed through the transfer gate 62 is applied to the other input terminal of the AND circuit 69 via the delay circuit 50, the signal "1" is output from the AND circuit 69.
As a result, the R-S flip-flop 64 is set and a signal "1" is output from its output terminal Q. Then, the monostable multiviprator 63 is triggered to output a pulse signal, and the rising temperature value storage unit 55, which receives this pulse signal at the terminal CK, outputs the temperature value signal Sd ₂ from the shift register 48. The current temperature value Ds is stored as the current temperature value Ds. At the same time, the adder 53 and the auxiliary adder 54, which have received the pulse signal at the terminal CK, calculate the rising temperature value Ds input to each terminal B and the signal value input to each terminal A. The addition result values U ₅₃ and U ₅₄ are stored, and the addition result values U ₅₃ and U ₅₄ are output. At this time, the terminal A of the adding section 53 receives the measurement result of the cooked rice amount measuring section 86 among the added temperature values D ₃₆ , D ₃₇ , D ₃₈ stored in the fifth to seventh storage sections 36 to 38, respectively. The terminal A of the auxiliary adder 54 receives the additional temperature values D ₃₉ , D 40 , D ₄₁ for double-cooking stored in the eighth to tenth storage units 39 to ₄₁ . Of these, an additional temperature value for double cooking is given according to the measurement result of the rice cooking amount measuring section 86.

Also, at time _t3 , the R-S flip-flop 64
is set, the signal “1” from the output terminal Q is sent to the AND circuit 72 via the OR circuit 76.
Since the clock pulse Pc is applied to one input terminal of the counter 21, the AND circuit 72 allows the clock pulse Pc applied to the other input terminal to pass, and the counter 21 starts counting.
1. The timer 88 consisting of the comparison section 29 and the thirteenth storage section 44 starts its timer operation from time _t3 .

Now, the addition result value U ₅₃ of the addition section 53 is
0, and when the temperature value signal Sd exceeds the addition result value _U53 at time _t4 , the comparison unit 30 outputs a signal "1".
It is applied to one input terminal of the AND circuit 75.
At this time, the other input terminal of the AND circuit 75 receives a signal "1" from the R-S flip-flop 64.
is given, the AND circuit 75 outputs a signal “1”, and this signal “1” is output to the OR circuit 78.
is applied to the reset input terminal R of the R-S flip-flop 66 via the RS flip-flop 66. Therefore, the R-S flip-flop 66 is reset and the supply of the signal "1" to the drive circuit 14 is stopped, so the relay switch 13 is turned off and the heater 6 is cut off. It will be moved to the Rumurashi period.

During this uneven period, so-called double cooking is performed based on the addition result value _U54 of the auxiliary addition section 54. That is, the addition result value U ₅₄ of the auxiliary addition section 54 is compared with the temperature value signal Sd in the comparison section 31, and as the temperature of the pot 5 decreases due to the power outage of the heater 6, the value U 54 is calculated at time t _5.
When the temperature value signal Sd becomes equal to the addition result value U ₅₄ , a signal “1” is output from the comparator 31 and applied to the third input terminal of the three-input type AND circuit 74 . At this time, the first and second
Since the signal “1” is applied to the input terminals from the comparator 29 and the R-S flip-flop 64, the AND circuit 74 outputs the signal “1”, and this signal “1” is passed through the OR circuit 77. and is applied to the set input terminal S of the R-S flip-flop 66. Therefore, the R-S flip-flop 66 is set and the signal "1" is again given to the drive circuit 14, so the relay switch 13 is turned on and the heater 6 is re-energized, thereby reheating the pot 5. The rice is cooked twice.

Thereafter, when the temperature value signal Sd exceeds the addition result value U ₅₃ of the adding section 53 in accordance with the temperature rise of the pot 5 due to the double cooking, the heater 6 is cut off in the same manner as described above. , the temperature value signal Sd is added to the auxiliary adder 54 in response to a decrease in the temperature of the pot 5 due to the power outage.
When the sum becomes equal to the addition result value _U54 , the heater 6 is energized in the same manner as described above, and this operation is repeated. Then, at time t ₆ , which is 15 minutes after time t ₃ , the count value of the counter 29 becomes equal to the timer time value T ₄₄ stored in the thirteenth storage unit 44, so that the comparison unit 29 outputs the signal “0”. ” will be output. Then, the signal "0" is inverted to signal "1" by the NOT circuit 85 and then applied to the reset input terminal R of the R-S flip-flop 66 via the OR circuit 78, thereby resetting the R-S flip-flop 66. Therefore, the relay switch 13 is turned off by the drive circuit 14, and the heater 6 is cut off. At the same time, the output of the AND circuit 73 that receives the signal "0" from the comparator 29 is inverted from the signal "1" to the signal "0", so the display circuit 15 turns off the rice cooking display lamp (not shown). become.

As mentioned above, rice is cooked by turning on the start switch 16.
If the start switch 16 is turned on without rice or water being stored in the rice cooker, it is dangerous to run into a so-called empty cooking state. However, in this embodiment, the above-mentioned danger is prevented as described below. In other words, in the case of empty cooking,
As the temperature of the pot 5 rises as shown by the two-dot chain line in FIG. 3, the rising temperature value Ds no longer exists. When the pot temperature exceeds the upper limit value D ₃₃ stored in the storage unit 33 of No. 2, the comparison unit 27 outputs the signal “1” as described above, so the AND circuit 70 outputs the signal “0”. In this way, the transfer gate 62 is turned off, and at the same time, the signal "1" from the comparator 27 is applied to one input terminal of the AND circuit 71. At this time, since the signal "0" from the R-S flip-flop 64 is applied to the other input terminal of the AND circuit 71 via the NOT circuit 83, the signal "1" is output from the AND circuit 71. be done. Then, the above signal “1” is sent to the OR circuit 78
Since the signal is applied to the reset input terminal R of the R-S flip-flop 66 via ”
Since the signal is inverted and applied to one input terminal of the AND circuit 73, the AND circuit 73 receives the signal "0".
starts to be output and the rice cooking indicator lamp turns off. In this way, the temperature of pot 5 reaches the upper limit of pot temperature.
When D ₃₃ is exceeded, the heater 6 is cut off, thereby preventing the danger of dry cooking.

According to the present embodiment described above, the additional temperature values D ₃₆ , D ₃₇ ,
D Selectively add one of ₃₈ to the addition result value
Temperature value signal obtained by obtaining U ₅₃ and measuring the temperature of pot 5
When Sd exceeds the above addition result value _U53 , heater 6
In this case, the temperature value at the time of startup, which is the standard for when to turn off the heater 6, is
Ds is not a fixed value but a value obtained by measuring the actual temperature gradient of the pot 5 between the pot temperature lower limit D ₃₂ and the pot temperature upper limit D ₃₃ each time. The power-off timing of the heater 6 is accurately controlled without being affected by error factors such as the contact state with the thermistor 8, ambient temperature, secular changes in the characteristics of the thermistor 8, variations during mass production, and changes in atmospheric pressure. be able to. Moreover, in this case,
Since the selection of the additional temperature values D ₃₆ , D ₃₇ , and D ₃₈ is performed according to the actual rice cooking amount measured by the rice cooking amount measuring section 86, the power cutoff timing of the heater 6 is controlled depending on the actual rice cooking amount. It can be done even more precisely depending on the amount.

Further, according to this embodiment, the double cooking is not controlled by time as in the conventional method, but by controlling the temperature value Ds at the time of rising.
In this case, the timing for re-energizing the heater 6 for double-cooking is changed according to the actual amount of cooked rice measured by the amount measuring section 86. Double cooking can also be controlled accurately.
In particular, when the above-mentioned double cooking is performed, the above-mentioned reference temperature value Ds
, the preset additional temperature value for double cooking
The heater 6 is intermittently energized based on the addition result value U ₅₄ obtained by selectively adding one of D ₃₉ , D ₄₀ , and D ₄₁ , but the above-mentioned additional temperature value for double cooking is
D ₃₉ , D ₄₀ , D ₄₁ are the addition temperature values D ₃₆ , D ₃₇ , which correspond to the addition result value U ₅₄ for setting the finished cooking temperature.
Since these values are lower than D ₃₈ , the double-cooking heating is performed at a temperature lower than the rice-cooking end temperature (U ₅₃ ). Therefore, as a result of double-cooking and heating being carried out at a relatively low temperature, even though the rice is already cooked and the amount of water in the pot 5 is relatively reduced, This effectively prevents the rice from burning and ensures that the rice becomes alpha.

Furthermore, according to this embodiment, the calculation for measuring the rising temperature value Ds is stopped until the temperature of the pot 5 exceeds the lower limit value _D32 of the pot temperature. The rising time of the temperature of the pot 5 shown in Fig. 3 and the time point indicated by B in Fig. 3 (the point at which the heat applied to the pot 5 begins to be mainly transferred to the rice and water) were mistakenly recognized as the rising temperature value. Therefore, there is no possibility of malfunction.

In addition, in the above embodiment, when cooking twice, the pot 5
Although reheating is performed multiple times, in this case, the additional temperature value for double-cooking may be different for each reheating. Furthermore, in the above embodiment, it goes without saying that the heat retention process may be performed after the unevenness period ends.

[Effects of the Invention] According to the present invention, as is clear from the above description, the end timing of the heating operation for cooking rice can be determined without considering the influence of the contact state between the pot and the temperature sensor, the ambient temperature, etc. It is possible to control the temperature extremely accurately without causing any damage, thereby preventing the rice from burning, and also by reheating the pot after the rice is finished cooking, so-called double cooking, it is possible to ensure that the rice becomes alpha. At the same time, it is possible to provide a rice cooker that can effectively prevent rice from burning during double cooking.

[Brief explanation of the drawing]

The drawings relate to one embodiment of the present invention.
The figure is a partially cutaway side view of the rice cooker, FIG. 2 is a block diagram showing the electrical configuration, and FIG. 3 is a diagram showing how the temperature of the pot changes. In the figure, 5 is a pot, 6 is a heater (heating means), 8 is a thermistor (temperature measuring means), 11 is a control circuit (control means), 32 is a first storage section (lower limit value storage section), and 33 is a first storage section. 2 storage section (upper limit storage section), 46
53 is a temperature converter (monitoring means); 53 is an adder; 54 is a temperature converter;
86 is an auxiliary adder, 86 is a cooked rice amount measuring unit, 87 is a calculation unit, and 88 is a timer.

Claims (1)

[Claims] 1. A heating means for heating the pot, a temperature measuring means for sensing the temperature of the pot, a means for monitoring the sensing output from the temperature measuring means, and a method for detecting a flat slope of the temperature change monitored by the pot. At the same time, the heating means for the pan is stopped at a temperature value obtained by adding a predetermined temperature value to the detected temperature value, and thereafter the heating means is intermittently reheated at a temperature lower than the added temperature value. A rice cooker characterized by comprising: