JPH0738830B2 - rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention obtains a boiling detection signal when the water in a pot is in a boiling state, and uses this boiling detection signal for rice cooking control. The rice cooker that I was supposed to do.

(Prior Art) In recent rice cookers, various rice cooking controls, specifically, for example, when rice is cooked, by heating the rice cooking heater with a large output until the water in the pan boils, In addition to satisfying the condition of so-called "medium pappa", which is one of the well-known conditions for deliciously cooking rice, the heater output is reduced after boiling to prevent the rice from burning, thus Control to cook deliciously,
Alternatively, when cooking rice porridge, the control for reducing the output of the rice cooking heater to prevent spillage is performed after the water in the pan boils, but in the case of performing such control, It is necessary to detect whether or not the water in the pan is in a boiling state. For this reason, in the conventional rice cooker, it is most common to detect the temperature of the pan and judge that it is in the boiling state when the detected temperature rises to a predetermined upper limit temperature.

(Problems to be Solved by the Invention) In the case of the above configuration, in order to accurately detect the boiling state, it is desirable to set the upper limit temperature near 100 ° C. However, when the upper limit temperature is set near 100 ° C in this way, the contact state between the temperature sensor part for detecting the pan temperature and the pan, the variation in the circuit constant of the temperature sensor part, and the aging of its characteristics Due to changes, changes in atmospheric pressure, or changes in the boiling point due to the addition of seasonings into the pan when making cooked rice, etc. It may not be detected even after a certain period of time, and in reality, the upper limit temperature is set to around 80 ° C. in anticipation of such fluctuation.
For this reason, the conventional boiling detection means has a problem that the boiling state in the pan is extremely inaccurately detected, which in turn makes it impossible to accurately control the rice cooking by the rice cooker.

The present invention has been made in view of the above circumstances, and an object thereof is to be able to detect a boiling state of water in a pan extremely accurately regardless of the amount of rice cooked by the pan, and to detect the result. To provide a rice cooker that can accurately perform rice-cooking control based on the rice cooker and can perform the re-detection operation of the boiled-state more accurately thereafter even if the boiling-state is once erroneously detected. is there.

[Structure of the Invention] (Means for Solving the Problems) The present invention determines that the pot temperature is a boiling state when the time-series gradient of the pot temperature is equal to or lower than a predetermined target temperature gradient, and a boiling detection signal. And a heating output control means for reducing the output of the heating means for cooking rice when the boiling detection signal is output, and a state in which the output of the heating means is reduced by the heating output control means. After that, when the temperature detection signal according to the temperature of the pan falls by a predetermined temperature range or more, an erroneous boiling detection signal is output to reactivate the boiling detection means and the heating output control means is returned to the initial state. Along with the detection and compensation means, respectively, a rice cooking amount detecting means for outputting a rice cooking amount signal according to the rice cooking amount is provided, and the boiling detecting means sets the target as the rice cooking amount indicated by the rice cooking amount signal increases. With varied to degree gradient decreases is obtained by the configuration as reset increase the target temperature gradient when it is re-operated by the erroneous boiling detection signal.

(Operation) In general, the time-series gradient of the pot temperature has a property of gradually decreasing as the water in the pot approaches a boiling state. Then, the boiling detection means in the present invention is configured to output a boiling detection signal by determining that the pan temperature is a boiling state when the time-series temperature gradient of the pot temperature becomes equal to or lower than a predetermined target temperature gradient. By setting the target temperature gradient appropriately in advance, the boiling state of water in the pot can be detected. In particular, in this case, the rising gradient of the pan temperature varies depending on the size of the cooked rice, but the boiling detection means changes the target temperature gradient so as to match the cooked rice. The boiling state can be accurately detected. Then, when the boiling detection signal is output from the boiling detection means, the heating output control means will decrease the output of the heating means, which is one of the conditions for cooking rice deliciously at the time of rice cooking. It is possible to accurately perform control such as satisfying the condition of "medium papper" or preventing spillage when cooking porridge. On the other hand, when the boiling detection signal is erroneously output from the boiling detection means for some reason before the water in the pan is in a boiling state, when the output of the heating means is decreased by the heating output control means, the pan temperature Will be reduced. When the decrease range of the pot temperature becomes equal to or larger than the predetermined temperature range, the boiling detection compensating means outputs an erroneous boiling detection signal, and the boiling detecting means is reactivated. In such a case, the time series gradient of the pot temperature becomes larger than the previous boiling state detection time due to the progress of evaporation of water in the pot. Since the target temperature gradient is reset to a large value during the re-operation as described above, there is no possibility that the boiling state will be inaccurately detected.

(Example) In FIG. 2, 1 is a rice cooker body including an inner frame 2 and an outer frame 3 and the like, 4 is a lid, 5 is a pot removably housed in the inner frame 22, and 6 is this pot 5. For example, it is a rice cooking heater having a rated output of 600 watts as a heating means installed in the space between the bottoms of the inner frame 2 and the outer frame 3 so as to be heated. 7 is the inner frame 2
Is a heat-sensitive cap arranged so as to be vertically movable so as to penetrate through the bottom of the pot, which is always urged upward by the spring force of the compression coil spring 8 and the pot 5 is housed in the inner frame 2. It is arranged so as to be in pressure contact with the outer bottom portion of the pot 5. 9 is a thermistor, for example, as a heat-sensitive element provided in the heat-sensitive cap 7 to detect the temperature of the pot 5, and 10 is only when the pot 5 made of rice and water is stored in the inner frame 2. It is a pan switch for preventing empty cooking which is pressed by the heat-sensitive cap 7 and turned on. Further, 11 is an operation panel installed on the side surface of the rice cooker body 1, and 12 is a case arranged on the outer bottom portion of the rice cooker body 1.
The temperature detected by the thermistor 9 and the operation panel
A control circuit 13 for controlling the on / off of the heater 6 based on the input from 11 is housed.

FIG. 1 shows the configuration of the control circuit 13 and the portions related thereto, which are directly related to the gist of the present invention, and will be described below.

That is, 14 is, for example, a triac as a switching element, which is connected between both terminals of the AC power source 5 through the heater 6 and the pan switch 10 in series. Reference numeral 16 is a photocoupler including a light emitting diode 16a and a phototransistor 16b, and the half-wave voltage of the AC power supply 15 is applied to the light emitting diode 16a via the diode 17 and the resistor 18. Reference numeral 19 is a DC constant voltage circuit that receives the output of the AC power supply 15, and power is supplied from the output lines La and Lb to each circuit section described below.

Reference numeral 20 denotes an initialization circuit which is, for example, a differentiation circuit, and outputs an initialization pulse P ₀ every time the power is turned on. Reference numeral 21 is a waveform shaping circuit that shapes the output of the photocoupler 16 (voltage output corresponding to the half-wave output of the AC power supply 15) into a rectangular wave. Reference numeral 22 is a time signal obtained by dividing the output of the waveform shaping circuit 21, for example, 1 the first frequency divider for generating a second periodic clock pulses P _1, 23 is a second divider for outputting a clock pulse P ₂ of the same time signal serving for example 10 second cycle by dividing the clock pulse P ₁ Circuit. 24 is a temperature detecting means 25 together with the thermistor 9
Which is an A-D converter, which outputs a temperature detection signal Sd of a digital value corresponding to the temperature of the pot 5 detected by the thermistor 9.

26 and 27 are temperatures used to detect the amount of cooked rice, for example 70 ° C each
And a first and second temperature value storage unit for storing numerical values corresponding to 80 ° C., and a third temperature value storage unit 28 for storing numerical values corresponding to a predetermined lower limit temperature, for example, 90 ° C. Reference numeral 29 is a fourth temperature value storage unit which stores a numerical value corresponding to 110 ° C., for example. Further, reference numerals 30 to 39 are fifth to fourteenth temperature value storage sections, which store the respective numerical values described below, for example, as described in FIG. That is, a numerical value corresponding to 2 ° C. is stored in the fifth temperature value storage unit 30,
The eighth and eleventh temperature value storage units 31, 33 and 36 respectively store 3 ° C.
The numerical values corresponding to 1 ° C. are stored in the seventh and tenth temperature value storage sections and 35, respectively.
And, the twelfth temperature value storage units 34 and 37 store numerical values corresponding to ° C respectively, and the thirteenth temperature value storage unit 38 stores numerical values corresponding to 112 ° C as the heater power interruption temperature Dz, 14th
In the temperature value storage unit 39, the temperature Dr.
A numerical value corresponding to 103 ° C is stored.

Numerals 40 and 41 are first and second time value storage sections which store the numerical values corresponding to, for example, 2 minutes and 4 minutes, respectively, which serve as a reference when detecting the amount of cooked rice. Reference numerals 42 to 51 denote third to twelfth time value storage sections, which store, for example, the respective numerical values described below as described in FIG. That is, the third time value storage unit 42 stores a numerical value corresponding to 7 minutes, the fourth time value storage unit 43 stores a numerical value corresponding to 9 minutes, and the fifth and eighth time values are stored. Numerical values corresponding to 0 seconds are stored in the storage units 44 and 47, and numerical values corresponding to 10 seconds are stored in the sixth and ninth time value storage units 45 and 48, respectively. Numerical values corresponding to 20 seconds are stored in the time value storage units 46 and 49, respectively, and numerical values corresponding to 30 seconds as the twice-cooking heating reference time N are stored in the eleventh time value storage unit 50.
The time value storage unit 51 of 12 stores a numerical value corresponding to 15 minutes as the uneven running time M.

Reference numerals 52 to 64 denote comparator circuits which output a high level signal from the output terminal C when the respective input values to the input terminals A and B have a relation of A ≧ B and output terminal C when the relation of A <B. Outputs a low level signal. Also, 65 is a comparator circuit having an enable terminal En, which is
The same operation as that of the comparison circuits 52 to 64 is performed only in the state where the high level signal is received at, and the low level signal is always output from the output terminal C when the enable terminal En receives the low level signal. 66 and 67 are subtraction circuits, which subtract the input value to the input terminal E from the input value to the input terminal D and output the subtraction result from the output terminal F. 68 to 71 are addition circuits, which add the input value to the input terminal X and the input value to the input terminal Y and output the addition result from the output terminal Z. Reference numerals 72 to 75 are counters that count the number of input pulses to the clock terminal CK and output the count value from the output terminal Q. When the pulse signal is received at the reset terminal R, the count content is initialized. ing. 76 to 79 and 13
Reference numeral 9 is a trigger circuit, which outputs a trigger pulse P ₃ for a short time when its input signal rises. 80 is a delay circuit,
This delays the input signal for a short time and outputs it.

Reference numeral 81 is a shift register having, for example, 24 unit registers, and this inputs the data terminal D to the first unit register 81a every time a pulse signal is received at the clock terminal φ.
It is configured such that the old storage data is sequentially shifted to the upper unit register each time new data is read, and the storage data is initialized when a pulse signal is received at the reset terminal R. It is designed to change. Then, the shift register 81 is configured to output the storage data of, for example, the 12th unit register 81b, the 18th unit register 81c, and the 24th unit register 81d. . Reference numeral 82 denotes a memory circuit, which is adapted to be initialized when a pulse signal is received at its reset terminal R, and has a configuration for storing the value first inputted to the input terminal D from such an initialized state. Has been done. Reference numeral 83 denotes a heater drive circuit that outputs the gate signal Sg only when it receives a high level signal and supplies it to the gate terminal of the triac 14, and 84 denotes a duty ratio control circuit that is driven only when a high level signal is received. The duty ratio control circuit 84 outputs a pulse-shaped control signal Sc having a duty ratio of 50%, for example, during its driving. The transfer gates 85 to 100 are conductive only when the gate terminal receives a high level signal.

101 and 102 are a start switch for starting rice and a stop switch for stopping rice, which are provided on the operation panel 11, respectively, and these are composed of momentary type push button switches, and are connected to the corresponding line only when turned on. It outputs pulse signals (high-level signals) P ₄ and P ₅ , respectively. Further, 103 to 106 and 132 are RS flip-flops, 106 to 115 and 13 to 135 are AND circuits, and 116 to 118.
Reference numerals 136 and 136 are OR circuits, and 119 to 125 are inverters.

The first and second frequency dividing circuits 22 and 23 and the AND circuit 108 constitute the time measuring means 126, and the first and second temperature value storage units 26 and 2 are provided.
7, first and second time value storage units 40, 41, comparison circuits 52, 53, 56, 57,
The counter 72, the AND circuits 106, 109 and the inverters 119, 120 constitute the cooked rice amount detecting means 127, and the first temperature value storage unit 28, the fifth temperature value storage unit 30, the comparison circuits 54, 65, the subtraction circuit 6
6, the delay circuit 80, the shift register 81, and the transfer gates 85 to 87 constitute the boiling detection means 128, and the fourth temperature value storage unit 29, the third and fourth time value storage units 42 and 43, and the comparison circuit 58. , 59, counter 73, AND circuits 107, 110 and inverter 12
The correction means 129 is composed of 1,122. Also,
14 temperature value storage unit 39, 5th to 12th time value storage units 44 to 5
1, comparison circuit 62 to 64, addition circuit 70, 71, counter 74, 75, trigger circuit 78, 79, transfer gate 95 to 100, AND circuit 114, 1
The double-cooking control means 130 is composed of the 15 and the inverter 125, and includes a sixth temperature value storage unit 31, a comparison circuit 60, and a subtraction circuit 6.
7, memory circuit 82, transfer gate 88, trigger circuit 76, 13
9, R-S flip-flop 132, AND circuit 133 to 135, OR circuit 1
The boiling detection compensating means 131 is configured by the 17 and the inverter 123, and the heater driving circuit 83, the duty ratio control circuit 84, R
-S flip-flop 104, AND circuits 112 and 113, OR circuit 118 and inverter 124 constitute heater output control means 137 as heating output control means, and further comparison circuits 61 and R.
-S flip-flop 105, adder circuits 68, 69, temperature value storage section
32-38 and transfer gates 89-94 constitute rice cook end control means 138.

Next, the operation of the above configuration will be described with reference to FIGS. 3 and 4. 3 (A) and 3 (B) show the time-dependent characteristics of the temperature detected by the thermistor 9 (that is, the temperature of the pot 5) and the output of the heater 6, respectively, and FIG. 4 shows the comparison circuit 52. , 53,54,55,60,61,62,63,64,65, duty ratio control circuit 84, start switch 101, R-S flip-flops 103, 104, 105, 132 set output terminals Q, AND circuit 10
The respective output waveforms from the 6, 107, 113, 115 and the OR circuit 118 are shown in correspondence with the respective codes.

That is, when the pan 5 containing rice and a required amount of water is stored in the inner frame 2, the pan switch 10 is turned on according to the storage. When the power is turned on in this state, the DC power supply circuit 19 and the photocoupler 16 are driven, and the initialization pulse P ₀ is output from the initialization circuit 20, so that the initialization pulse P ₀ causes R- The S flip-flop 103 is reset and a high-level signal is output from its reset output terminal. The high-level signal initializes the counters 72, 74 and the memory circuit 82 and resets the RS flip-flop 105. . At this time, the high level signal from the RS flip-flop 103 is ORed.
Trigger pulse P from trigger circuit 76 received via circuit 117
_{Since 3} is output, the shift register 81 is initialized by the trigger pulse P ₃ and the OR circuit 117 is also used.
The RS flip-flop 104 is reset and the RS flip-flop 132 is set by the high level signal output via the.

After that, when the start switch 101 is turned on at time t ₀ (see FIGS. 3 and 4), the RS flip-flop 103 is turned on by the pulse signal P ₄ output in response to the turning on.
Is set, and the trigger circuit 139 outputs the pulse signal P ₃ by the high level signal from the set output terminal Q, so that the RS flip-flop 132 is reset and the high level signal is given to the AND circuits 112 and 113. To be At this time, since the low level signal from the set output terminal Q of the RS flip-flop 104 in the reset state as described above is given to one AND circuit 112, its output remains the low level signal. But the other
The AND circuit 113 is supplied with the low level signal from the set output terminal Q of the RS flip-flop 104 by being inverted into a high level signal by the inverter 124, and
The RS flip-flop 105 which is also in the reset state
Since the high level signal is given from the reset output terminal of, the AND circuit 113 consequently outputs the high level signal to the heater drive circuit 83. For this reason,
The gate signal Sg is output from the heater driving circuit 83 and the triac 14 is turned on. In response to this, the AC power source 15 energizes the heater 6 via the pan switch 10 and the triac 14 to heat the pan 5. , The rice cooking process is started. As the rice cooking process progresses, the temperature of the pan 5 rises as shown in FIG.
Outputs a temperature detection signal Sd corresponding to the temperature of the pot 5.

Then, when the temperature of the pan 5 rises to 70 ° C. stored in the first temperature value storage unit 26 (time t ₁ ), the cooked rice amount detecting means 127 first operates. That is, in the cooked rice amount detecting means 127, the comparison circuit 52 corresponds to “70 ° C.” in which the temperature detection signal Sd input to the terminal A is input to the terminal B from the first temperature value storage unit 26. The low level signal is output until time t ₁ when the temperature value becomes equal to the temperature value, and the high level signal is output after the time t ₁ . Further, at the comparison circuit 53, the time t at which the temperature detection signal Sd input to the terminal B becomes larger than the temperature value corresponding to “80 ° C.” input from the second temperature value storage unit 27 to the terminal A. Output high level signal up to ₂ ,
After that time t _2, a low level signal is output. Therefore,
Since the high-level signals are output from both comparison circuits 52 and 53 and given to the AND circuit 106 only during the period from time t _{1 to} t ₂ , the pulse signal of the 1-second cycle from the first frequency dividing circuit 22 is only during this period.
P ₁ passes through the AND circuit 106 and the clock terminal CK of the counter 72
Given to. Therefore, as a result, the count value of the counter 72 becomes a value corresponding to the time Ta (the time from time t ₁ to t ₂ ) required for the temperature of the pot 5 to rise from 70 ° C. to 80 ° C. The time Ta measured as described above has the property of increasing or decreasing in proportion to the amount of cooked rice, and the counter corresponding to this time Ta
The amount of cooked rice is determined based on the count value of 72.
That is, the count value of the counter 72 is compared with the respective numerical values (corresponding to 2 minutes and 4 minutes) stored in the first and second time value storage units 40 and 41 by the comparison circuits 56 and 57, respectively. At this time, the comparison circuit 56 outputs a low level signal when the count value of the counter 72 is smaller than the equivalent value of 2 minutes (in other words, when the rice cooking amount is relatively small), and the low level signal is output by the inverter 119. It is inverted to a high level signal which is a quantity signal and is given to the line L ₁ . The comparator circuit 57 is a counter.
When the count value of 72 is equal to or greater than the value equivalent to 4 minutes (in other words, when the amount of cooked rice is relatively large), a high level signal which is a cooked rice amount signal is output and given to the line L ₃ . Further, when the count value of the counter 72 is equal to or greater than the value equivalent to 2 minutes and smaller than the value equivalent to 4 minutes (in other words, when the amount of cooked rice is medium), the comparison circuit 56 outputs a high level signal, which is an AND circuit. 109
The low level signal is output from the comparison circuit 57, is inverted by the inverter 120 into the high level signal, and is applied to the other input terminal of the AND circuit 109. The AND circuit 109 outputs a high level signal which is a rice cooking amount signal and gives it to the line L ₂ . In short, the cooked rice amount detecting means 127 determines the amount of cooked rice based on the time required for the temperature of the pan 5 to rise from 70 ° C. to 80 ° C., and the cooked rice amount signal (high level signal) indicating the determination result. ) Is selectively output to lines L ₁ , L ₂ and L ₃ .

Thus, in this case, the RS flip-flop 132
Is reset and the high level signal from the reset output terminal is input to the AND circuits 133 to 135, the AND circuits 133 to 135 pass the rice cooking amount signal from the rice cooking amount detecting means 127. Is allowed. Therefore, when the amount of cooked rice detected as described above is relatively small, the transfer gates 85, 89, and 95 that receive the output from the AND circuit 133 via the OR circuit 136 at the gate terminal are in a conductive state, and are detected. When the amount of rice cooked is medium, AN is connected to the gate terminal.
Transfer gates 86, 90, which receive the output from the D circuit 134,
When 96 is conductive and the detected rice cooked amount is relatively large, the transfer gates 87, 91 and 97 which receive the output from the AND circuit 135 at the gate terminals are conductive. At this time, the temperature values stored in the seventh, eighth, and ninth temperature value storage units 32, 33, and 34 corresponding to the transfer gates 89, 90, and 91 that are selectively turned on as described above are not detected by the heater. Utility temperature
Dz (temperature value stored in the thirteenth temperature value storage unit 38, that is, 11
2 ° C.), and these storage temperature values are selectively given to the input terminal Y of the adder circuit 68 according to the magnitude of the detected cooked rice amount.
The temperature value thus input is added to the numerical value (heater disconnection temperature Dz) stored in the thirteenth temperature value storage unit 38 and output. Also, the time values stored in the fifth, sixth, and seventh time value storage units 44, 45, and 46 corresponding to the transfer gates 95, 96, and 97 that are selectively turned on as described above are also twice. Cooking time reference time N (time value stored in eleventh time value storage unit 50,
That is, each storage time value is selectively given to the input terminal Y of the adder circuit 70 according to the magnitude of the detected cooked rice amount. The time value thus input is added to the numerical value stored in the eleventh time value storage unit 50 (twice heating standard time N) and output.

After that, when the temperature of the pan 5 further rises and becomes equal to or higher than the lower limit temperature “90 ° C.” stored in the third temperature value storage unit 28 (time
t ₃ ), each input value to the input terminals A and B of the comparison circuit 54 is A
As a result of ≧ B, the output of the comparison circuit 54 is inverted to a high level signal. As a result, the AND circuit 108 receiving the high level signal at one input terminal inputs to the other input terminal, that is, the pulse signal P ₂ of the 10-second cycle from the second frequency dividing circuit 23 in the timing means 126. While allowing passage, similarly, the comparator circuit 65 which receives the high level signal from the comparator circuit 54 at the enable terminal En via the delay circuit 80 becomes operable, and accordingly the boiling detection means 128 boils. The detection function will be enabled.

That is, when the pulse signal P ₂ passes through the AND circuit 108, the pulse signal P ₂ is given to the clock terminal φ of the shift register 81, so that the shift register
81 is an input to the data terminal D, that is, the temperature detection signal Sd
Is read and stored every 10 seconds, and the old temperature detection signal Sd is sequentially shifted to the upper unit register every time a new temperature detection signal Sd is read. As a result, the temperature detection signal Sd 120 seconds (2 minutes) before the current temperature detection signal Sd is stored in the twelfth unit register 81b.
The current unit temperature detection signal Sd is stored in the second unit register 81c.
The temperature detection signal Sd 180 seconds (3 minutes) before is stored, and the second
The current temperature detection signal Sd is stored in the fourth unit register 81d.
The temperature detection signal Sd 240 seconds (4 minutes) before is stored. At this time, the unit registers 81b, 81c and 81d
Each stored data of the transfer gate 8 corresponding to each
Although it is applied to the input terminal E of the subtraction circuit 66 via 5,86 and 87, as described above, when the amount of cooked rice is relatively small, the transfer gate 85 is in the conductive state, and the unit The data stored in the register 81b is given to the input terminal E of the subtraction circuit 66, and similarly, when the amount of cooked rice is medium and relatively large, the unit registers 81c and 81c, respectively.
Each stored data of d is given to the input terminal E of the subtraction circuit 66. A temperature detection signal is applied to the other input terminal D of the subtraction circuit 66.
Since Sd is directly input, the subtraction circuit 66 determines that the value indicated by the current temperature detection signal Sd is 2 minutes before, 3 minutes before, or 4 minutes before the reference time. The numerical value indicated by the detection signal Sd is subtracted, and the subtraction result is a time-series value of the temperature rise value of the pan 5 within a fixed reference time (2 minutes, 3 minutes, or 4 minutes), and thus the pan 5. The value corresponds to the temperature gradient.

Then, the temperature of the pan 5, that is, the rate of increase of the temperature detection signal Sd is
It has the property that the water in the pot 5 gradually decreases as it approaches the boiling state, and finally becomes approximately zero, so that the temperature rise value of the pot 5 within the reference time is equal to or less than the predetermined comparison temperature value. When it is detected that the inside of the pan 5 is in a boiling state, it can be determined. In this case, the rate of temperature rise of the pan 5 tends to become dull as the amount of cooked rice increases,
In order to perform accurate boiling detection, it is desirable to change the above reference time according to the amount of cooked rice. In this embodiment, in order to perform such accurate temperature detection, the reference time (that is, temperature detection). The amount of pulling time of the signal Sd) is automatically changed to any of 2 minutes, 3 minutes, and 4 minutes as described above. Then, in the comparison circuit 65, the subtraction circuit 66
Output (the temperature rise value of the pan 5 within the three-step reference time determined according to the amount of cooked rice) and the numerical value stored in the fifth temperature value storage unit 30 as the comparative temperature value (2 ° C.). When the temperature rise value of the pot 5 within the reference time is less than 2 ° C., in other words, the temperature rise gradient of the pot 5 becomes equal to or lower than a predetermined target temperature gradient. Then, the comparison circuit 65 outputs a boiling detection signal Sz composed of a high level signal (time t ₄ ).

Now, when the boiling detection signal Sz is output as described above, the heater output control means 137 functions. That is, at the time t ₄ , the memory content of the memory circuit 82 is initialized, and the numerical value (corresponding to 3 ° C.) stored in the sixth temperature value memory unit 31 is subtracted from the memory value. The output of the subtraction circuit 67 is a negative value, and the comparison circuit 60 is in the state of outputting a low level signal. Therefore, the comparator circuit 60 and the RS flip-flop 103 are connected to both input terminals of the OR circuit 117.
A low level signal is given from the reset terminal of the AND circuit, and this low level signal is inverted to a high level signal by the inverter 123 and given to one input terminal of the AND circuit 111. Therefore, when the boiling detection signal Sz (high level signal) is output at time t _{4 as} described above, the AND circuit 1
A high level signal is output from 11 and the RS flip-flop 104 is set. Then, the output of the AND circuit 113 which has been outputting the high level signal is inverted to the low level signal, and the set output terminals Q and R− of the RS flip-flops 103 and 104 are connected to the input terminals of the AND circuit 112, respectively.
A high level signal is applied from the reset output terminal of the S flip-flop 105, and a high level signal is output from the AND circuit 112. In response to this, a pulse with a duty ratio of 50% is output from the duty ratio control circuit 84. The state control signal Sc is output and given to the heater drive circuit 83. As a result, the triac 14 is turned on and off at a 50% duty ratio. At this time, since the rated output of the heater 6 is 600 watts, the heater 6 generates heat at an output of 300 watts, that is, half the rated output. become.

Further, when the RS flip-flop 104 is set at the time t ₄ , the trigger circuit 77 is driven and the trigger pulse P ₃ is output from this time.
The counter 73 is initialized by P ₃ and the transfer gate 88 becomes conductive, and the time
The temperature detection signal Sd at time t ₄ (corresponding to the temperature of the pan 5 at the time of boiling state detection) is stored in the storage circuit 82. Further, at this point, since sufficient water still remains in the pan 5 and the temperature does not exceed 100 ° C., the temperature detection signal Sd corresponding to the temperature of the pan 5 and the fourth temperature value storage unit Comparison circuit 5 comparing 29 stored values (corresponding to 110 ° C)
5 outputs a high level signal. Therefore, the AND circuit 107 which has received the high level signal and the high level signal from the reset output terminal of the RS flip-flop 105 causes the AND circuit 107 to output the pulse signal from the first frequency dividing circuit 22. Passing P ₁ (1 second cycle) is permitted. Therefore, the count value of the counter 73 initialized as described above indicates the elapsed time from the time t ₄ . When the rice cooking process further progresses and the inside of the pan 5 exhibits a so-called dry-up state, the temperature of the pan 5 suddenly rises. In this case, the temperature of the pan 5 is at time t ₅ When 110 ° C. is reached at, the inputs of the input terminals A and B of the comparison circuit 55 have a relation of A <B and their outputs are inverted to low level signals, so that the AND circuit 107 outputs the pulse signal P ₁ The passage is blocked, and the counting operation of the counter 73 is stopped. Therefore, as a result, the count value of the counter 73 is equal to the boiling detection signal.
Time required Tb from the time t ₄ when Sz is output to the time t ₅ the temperature of the pan 5 has reached 110 ° C. (corresponding to the duration of boiling)
Will be equivalent to.

The time Tb measured as described above is also the time t ₁ to t ₂ described above.
Like the time Ta up to, it has the property of increasing or decreasing in proportion to the amount of rice cooked, and also has the property of being affected by the ratio of rice and water when cooking rice, and the correcting means 129 uses the counter corresponding to the time Tb. Based on the 73 count value, the rice cooked amount detected by the rice cooked amount detecting means 127 is corrected as follows. That is, the count value of the counter 73 is compared with the respective numerical values (corresponding to 7 minutes and 9 minutes) stored in the third and fourth time value storage sections 42 and 43 by the comparison circuits 58 and 59, respectively. At this time, the comparison circuit 58 outputs a low level signal when the count value of the counter 73 is smaller than the value equivalent to 7 minutes (in other words, when the amount of cooked rice is relatively small), and the low level signal is output by the inverter 121. It is inverted to a high level signal and applied to line L ₄ .
Further, the comparison circuit 59 outputs a high level signal to the line L ₆ when the count value of the counter 73 is 9 minutes or more (in other words, when the amount of cooked rice is relatively large). And
When the count value of the counter 73 is equal to or larger than the value equivalent to 7 minutes and smaller than the value equivalent to 9 minutes (in other words, the amount of cooked rice is medium), the comparison circuit 58 outputs a high level signal, which is the AND circuit 110. Is applied to one input terminal of the AND circuit, and a low-level signal is output from the comparison circuit 59. This is inverted by the inverter 122 into a high-level signal, and the AND circuit 11
The signal is applied to the other input terminal of 0, and as a result, a high level signal is output from the AND circuit 110 and applied to the line L ₅ .

When the amount of cooked rice thus detected is relatively small, the transfer gates 92 and 98 whose gate terminals are connected to the line L ₄ are in a conductive state, and when the detected amount of cooked rice is medium, When the transfer gates 93 and 99 whose gate terminals are connected to the line L ₅ are in the conductive state and the detected rice cooking amount is relatively large, the transfer gates 94 and 100 whose gate terminals are connected to the line L ₆ are in the conductive state. Come to present. At this time, the tenth, eleventh, and twelfth corresponding to the transfer gates 92, 93, and 94 that are selectively conducted as described above.
The temperature values stored in the temperature value storage units 35, 36, 37 are also for correcting the heater disconnection temperature Dz (the temperature value stored in the thirteenth temperature value storage unit 38, that is, 112 ° C.). These storage temperature values are selectively given to the input terminal Y of the adder circuit 69 according to the length of the time Tb, and the adder circuit 69 adds the temperature values thus input. It is further added to the numerical signal from the circuit 68 (that is, the temperature value Dz for turning off the heater is added only by the temperature value corresponding to the size of the rice cooking amount detected by the rice cooking amount detecting means 127), thereby cooking rice. It serves to correct the added temperature value by the amount detecting means 127 and thus the detected rice cooking amount. Also, the 8th, 9th, and 1st corresponding to the transfer gates 98, 99, and 100 that are also selectively conducted.
The time value stored in the time value storage unit 47, 48, 49 of 0 is also the twice-boiled heating reference time N (the
11 time value stored in the time value storage unit 50, that is, 300 seconds)
The storage time values are selectively given to the input terminal Y of the adder circuit 71 in accordance with the length of the time Tb. The calculated time value is further added to the numerical signal from the adding circuit 770 (that is, a value obtained by adding the time value corresponding to the magnitude of the cooked rice amount detected by the cooked rice amount detecting means 127 to the double-cooking heating reference time N). The added time is corrected by the rice cooked amount detecting means 127, and thus the detected cooked rice amount is corrected.

It is rice end control unit 138 to function in a subsequent time t _6. That is, the temperature of the pan 5 corresponds to the output from the adder circuit 69, that is, the cooked temperature of the rice (that is, the heater disconnection temperature Dz).
(112 ° C.), the temperature value corresponding to the amount of cooked rice detected by the cooked rice amount detecting means 127 and the temperature obtained by adding the correction temperature value by the correcting means 129 are reached), and the input terminals A and B of the comparison circuit 61 are reached. Since the respective input values for A have a relation of A ≧ B, and the high level signal is output from the comparison circuit 61, R
-S flip-flop 105 is set. Then R
The low level signal from the reset output terminal of the S flip-flop 105 is given to the AND circuit 112, and the AND circuit 1
Since the output of 12 is inverted to a low level signal, driving of the duty ratio control circuit 84 is stopped, and accordingly, the heater drive circuit 83 stops outputting the gate signal Sg and the triac 14
Is maintained in a turn-off state, that is, the heater 6 is turned off, and the rice cooking process is completed. At this time, the set output terminal Q of the RS flip-flop 105
Is applied to the AND circuits 114 and 115, and the AND circuit 114 permits the passage of the pulse signal P _{1. In} response to this, the double-cooking control means 130 functions to perform the unevenness. The process will be started. In summary,
The temperature of the pan 5 is a temperature value corresponding to the amount of cooked rice detected by the cooked rice amount detecting means 127 with respect to the heater disconnection temperature Dz of 112 ° C. (7th, 8th, 9th temperature value storage units 32, 33). , Any of the temperature values stored in 34) and the corrected temperature value by the correction means 129 (any of the temperature values stored in the tenth, eleventh, and twelfth temperature value storage units 35, 36, 37). When the cooking temperature reached by adding (1) is reached, the rice cooking process is completed and the process shifts to the Murashi process. The operation in this Murashi process will be described below. In the case of this embodiment, the cooked temperature is changed between 114 ° C. and 122 ° C. according to the stored contents of the seventh to thirteenth temperature value storage units 32 to 38.

The counter 75 in the twice-cooking control means 130 has counted the pulse signal P ₁ from the time when the power is turned on. Therefore, at the time t ₆ , the count value is at least the numerical signal output from the adder circuit 71 (main In the case of the embodiment, the maximum value is 100 seconds), and as a result, each input value to the input terminals A and B of the comparison circuit 64 has a relation of A <B, and the comparison circuit 64 outputs a low level signal. Is being output. Further, the other counter 74 in the twice-cooking control means 130 displays the time t
_{Since the} counting operation is started from ₆ , at this time, the respective numerical values inputted to the input terminals A and B of the comparison circuit 62 have a relation of A ≧ B, and the comparison circuit 62 outputs a high level signal. Has been done. When the heater 6 is cut off at time t ₆ , the temperature of the pan 5 gradually decreases after it overshoots as shown in FIG. 3, and the temperature of the pan 5 changes at time t ₇ . When the temperature is lowered to the double cooking start temperature Dr (103 ° C.) stored in the fourteenth temperature value storage unit 39, each input value to the input terminals A and B of the comparison circuit 63 becomes A ≧
Since the high-level signal is output in the relationship of B, the trigger circuit 78 that receives the high-level signal is the trigger pulse.
Will output the P _3, the counter 75 is initialized by the trigger pulse P _3. Then, the input values of the input terminals A and B of the comparison circuit 64 have a relationship of A ≧ B, and the comparison circuit 64 outputs a high-level signal.
A high level signal is given to all the input terminals of the D circuit 115, and the output of the AND circuit 115 is inverted to a high level signal. As a result, the heater driving circuit 83 which receives the high level signal from the AND circuit 115 turns on the triac 14 to re-energize the heater 6, and accordingly, the heating is performed twice. At this time, the count value of the counter 75 shows the elapsed time from the time t ₇ when the temperature of the pan 5 dropped to 103 ° C., and the count value corresponds to the output from the adding circuit 71 at the time t ₈ . The time (that is, for the standard time N (30 seconds) for cooking twice)
When a time value corresponding to the amount of cooked rice detected by the cooked rice amount detecting means 127 and a time obtained by adding a correction time value by the correcting means 129) are reached, each input value to the input terminals A and B of the comparison circuit 64 becomes A <B. Since the output of the comparison circuit 64 is inverted to the low level signal, the output of the AND circuit 115 is also inverted and the heater drive circuit 83 turns off the triac 14, and the heater 6 is disconnected. Electricity is turned on and cooking is stopped twice to stop heating. After that, the temperature of the pot 5 once rises due to double heating and then decreases to 103 ° C. At each time t ₉ and t ₁₁ , the heater 6 is re-energized in the same manner as described above to perform double heating. At the same time, such double heating is performed at each time T ₁₀ , t ₁₂ when the time when the count value of the counter 75 corresponds to the output from the adding circuit 71 has elapsed.
Will be stopped at.

When reaching the time t ₁₃ to unevenness stored in the time value storage unit 51 of the first 12 after the time t ₆ to the operating time M (15 minutes) has elapsed, corresponding to the count value above steaming operating time M of the counter 74 Since the output of the comparison circuit 62 is inverted to a low level signal when the value exceeds the above value, the state where the AND circuit 115 outputs the low level signal and thus the state where the heater drive circuit 83 is stopped is held, and the unevenness occurs. The process is finished.
When the output of the comparison circuit 62 is inverted to the low level signal as described above, the output of the inverter 125 is inverted to the high level signal and the trigger pulse P ₃ is output from the trigger circuit 79. _The RS flip-flop 103 is reset by ₃ and thereafter, the process proceeds to a heat retention step by a heat retention heater (not shown). In short, in the Murashi process, when the temperature of the pot 5 drops to 103 ° C., which is the temperature for starting cooking twice, the heater is re-energized, and the energizing time is the reference time N for heating twice. Time value corresponding to the rice cooking amount detected by the rice cooking amount detecting means 127 for 30 seconds (one of the time values stored in the fifth, sixth, and seventh time value storage units 44, 45, 46) ) And the correction time value by the correction means 129 (8th, 9th, 1st
When the time obtained by adding one of the time values stored in the time value storage units 47, 48, 49 of 0) is reached, the heater 6 is turned off and the heating is finished twice and the heating is ended. This is repeated, and in the case of the present embodiment, the above-mentioned twice-boiled heating time depends on the stored contents of the fifth to eleventh time value storage sections 44 to 50.
It varies between 30 and 70 seconds.

Now, up to this point, the operation when the temperature of the pot 5 rises without lowering after the boiling detection signal Sz is output at time t _{4 and} the output of the heater 6 is dropped to half of the rated value will be described. However, in the following, regarding the operation when the temperature of the pan 5 is lowered while the output of the heater 6 is reduced, the same operation as in FIGS. 3 and 4 is performed in FIGS. 5 and 6 respectively. Description will be given with reference to the drawings. That is, when the output of the heater is reduced to half, the temperature of the pot 5 drops when the water in the pot 5 is not yet boiling (in other words, when the boiling detection signal Sz is erroneously output). Such a phenomenon may occur, for example, seasoning such as soy sauce put in the pan 5 when making cooked rice is burned at the bottom of the pan 5, whereby the temperature of the water in the pan 5 is increased. It is considered that this is due to the increase in the gap between the temperature detected by the thermistor 9 and the temperature detected by the thermistor 9.

Then, when the output of the heater 6 is halved at time t _{4 in} FIGS. 5 and 6, the temperature of the pot 5 at that time (that is, the boiling detection means 128 is in the boiling state) as described above. The boiling detection signal Sd corresponding to the temperature of the pan 5 when it is detected that the above condition is stored in the storage circuit 82 in the boiling detection compensating means 131. At this time, the subtraction circuit 67 in the boiling detection compensating means 131 subtracts the value stored in the sixth temperature value storage unit 31 (corresponding to 3 ° C.) from the value stored in the storage circuit 82, and the subtraction result To the input terminal A of the comparison circuit 60. Therefore, after that, when the temperature of the pan 5 is lowered to the temperature value Tp, in other words, when the temperature detection signal Sd is decreased by a value equal to or more than 3 ° C. which is a predetermined temperature range (time
t ₄₁ ), the comparison circuit 60 outputs an erroneous boiling detection signal Se composed of a high level signal. Then, according to this, R
-S flip-flop 104 is reset and R
-S flip-flop 132 is set. Furthermore, at this time, since the trigger circuit 76 is driven according to the output of the false boiling detection signal Se, the shift register 81 is initialized by the trigger pulse P ₃ from the trigger circuit 76,
As a result, the boiling detection means 128 is restarted. Then, when the RS flip-flop 132 is set as described above,
Since the low level signal from the reset output terminal is input to the AND circuits 133 to 135, the AND circuits 133 to 135 block the passage of the cooked rice amount signal from the cooked rice amount detecting means 127. Further, since the high level signal from the set output terminal Q of the RS flip-flop 132 passes through the OR circuit 136, the transfer gates 85, 89 and 95 are rendered conductive. That is, when the boiling detection means 128 erroneously detects the boiling state, the temperature detection signal Sd two minutes before stored in the twelfth unit register 81b is given to the subtraction circuit 66, and therefore the subtraction is performed. Subtraction result of circuit 66 and fifth
The target temperature gradient indicated by the comparative temperature value (corresponding to 2 ° C.) stored in the temperature value storage unit 30 is reset to a large value corresponding to a relatively small amount of cooked rice. Further, in this case, when the boiling detection means 128 erroneously detects the boiling state as described above, the temperature value stored in the seventh temperature value storage unit 32 (the lowest correction temperature value corresponding to 1 ° C.) Is supplied to the adder circuit 68 via the transfer gate 89, so that the cooked temperature Doff is set low again. Further, in this case, when the boiling detection means 128 also erroneously detects the boiling state,
The time value stored in the fifth time value storage unit 44 (the lowest correction time value corresponding to 0 second) is given to the addition circuit 70 via the transfer gate 95, and therefore the second heating is performed. The energization time of the heater 6 (therefore, the heat generation amount of the heater 6) that is sometimes set is set low again.

On the other hand, in response to the reset of the RS flip-flop 104, the output of the AND circuit 112 is inverted to a low level signal, and the output of the AND circuit 113 is inverted to a high level signal,
A high level signal is continuously given to the heater drive circuit 83, and in response to this, the heater output control means 137 is returned to the initial state so that the heater 6 generates heat at the rated output, that is, 600 watt output. Become. Further, at this time, the boiling detection means 127 that has been re-operated as described above will perform the boiling state detection operation similar to that described above based on the newly set target temperature gradient again, for example, at time t.
_{When the} comparison circuit 65 outputs the boiling detection signal Sz at _42, the output of the heater 6 is halved again. Further, when the temperature of the pan 5 is lowered again after this, the same operation as described above is repeated, and thus the boiling detection compensating means 131 makes the detecting operation of the boiling detecting means 128 more accurate. To function.

According to this embodiment described above, the following effects can be obtained. That is, the state in which the water in the pot 5 is boiling is not detected based on the absolute upper limit temperature which is predetermined as in the conventional case, but when the water in the pot 5 is in the boiling state, the pot 5 The temperature gradient of is less than or equal to a predetermined target temperature gradient (specifically, the amount of change in the temperature of the pan 5 within a predetermined reference time is stored in the fifth temperature value storage unit 30 for comparison. Since the temperature is detected based on the temperature value (2 ° C. or less), the contact state between the heat-sensitive cap 7 and the bottom of the pan 5 and the thermistor 9 or A- which constitutes the temperature detecting means 25 are detected. It is assumed that there are variations in the circuit constants of the D converter 24, changes in its characteristics over time, changes in atmospheric pressure, or changes in the boiling point due to the addition of seasonings into the pan 5 when making cooked rice. Also, the boiling state of water in the pan 5 can be accurately detected. Further, when the boiling state is detected in this way, the boiling detection as described above becomes inaccurate when the amount of cooked rice is different, because the temperature rising gradient of the pan 5 changes according to the size of the amount of cooked rice. However, in the present embodiment, according to the size of the rice cooked amount detected by the rice cooked amount detecting means 127, the configuration for changing the target temperature gradient during boiling detection (specifically, when measuring the temperature gradient) Since the required reference time is changed), the boiling state of the water in the pan 5 can always be detected accurately even when the amount of cooked rice is different.

Furthermore, in the present embodiment, when the boiling state is erroneously detected for some reason, the boiling detection compensating means 131 detects this and reactivates the boiling detecting means 128,
Since the target temperature gradient for boiling detection at this time is set to be large again, the following effects are also obtained. That is, when the boiling detection means 128 is reactivated as described above, the time-series gradient of the temperature of the pot 5 is the previous boiling state due to the fact that the water in the pot 5 is being evaporated. Since it becomes larger than the detection time, there is a possibility that the new boiling state detection operation by the boiling detection means 128 becomes inaccurate,
In this case, the target temperature gradient is set again as described above, so that the boiling state is not detected inaccurately.

In this embodiment, the rice 6 is heated by the rated output until the boiling state is detected, and then the output of the heater 6 is halved.
In this case, since the boiling state is accurately detected as described above, it is possible to strictly control the above-mentioned rice cooking, so that the so-called "medium papa" condition, which is one of the conditions for deliciously cooking rice, is set. It can be fully filled,
It can be cooked on rice with less charring, and can be cooked well on the whole. Of course, since the boiling state in the pan 5 is accurately detected in this way, and the output of the heater 6 is halved after the boiling is detected,
When this configuration is applied to porridge cooking control, spillage can be reliably prevented. Further, in the present embodiment, the larger the rice cooking amount detected by the rice cooking amount detecting means 127,
In other words, the temperature of the heater 6 is cut off, that is, the temperature at which the rice is cooked, is increased during the dry-up process when a relatively large amount of unnecessary water remains in the pan 5. The rise can be made good. Moreover, in this case, since the correction means 129 is provided to correct the amount of cooked rice detected by the cooked rice amount detecting means 127 according to the length of the period in which the water in the pan 5 is in the boiling state, The rice cooking control according to the ratio of rice and water at the time of rice cooking can be performed more strictly. In addition, the twice-boiled heating time during the Murashi stroke is also changed to a time corresponding to the amount of cooked rice detected by the cooked rice amount detecting means 127 and corrected by the correcting means 129. The cooked rice can be made even more delicious as it can be fully and fully cooked. In addition, when making cooked rice, the boiling detection compensating means 131 compensates for the boiling detection error caused by the burning of the seasoning such as soy sauce put in the pan 5 and the like. Even if the temperature detected by the temperature detecting means 25 deviates from the actual temperature in the pan 5 due to the special condition in the pan 5 as described above, the boiling state of the water in the pan 5 Can be detected extremely accurately. Furthermore, in each of the above embodiments, the function of the boiling detection means 128 is activated only when the temperature of the pan 5 reaches the lower limit temperature (90 ° C.) stored in the third temperature value storage unit 28. Therefore, there is no possibility of erroneously detecting a period in which the temperature gradient is in a flat state as a boiling state, such as when the temperature of the pot 5 rises as indicated by G in FIG.

In the above embodiment, the cooked rice amount detecting means 127 for detecting the cooked rice amount based on the time required for the temperature of the pan 5 to rise from 70 ° C. to 80 ° C. is provided. The temperature value, that is, the stored value of the first and second temperature value storage units 26, 27 is not limited to this, and the amount of cooked rice is detected by measuring the total weight of the pan 5, etc. Alternatively, a cooked rice amount detecting means having another configuration may be provided. Of course, the stored contents of the other temperature value storage units 28 to 39, 136 to 138 and the time value storage units 40 to 51 are not limited to those in the above-described embodiments, and especially for the double heating control.
The numerical value stored in the storage unit 39 of 14 may be replaced with the numerical value stored in the storage circuit 82. Further, in the above embodiment, the duration of the boiling state is measured by the correction means 129 based on the numerical value (110 ° C.) stored in the fourth temperature value storage unit 29. It is also possible to detect the time point when the temperature of 5 rapidly rises and measure the boiling duration time based on the detection result. Further, in the above embodiment, the rice cooked amount detected by the rice cooked amount detecting means 127 is cranked in three stages, but it may be ranked in multiple stages. Of course, in this case, the boiling detecting means is used. The configurations of the 128 or 132 and the correction means 129 are also changed in accordance with this, but with such a configuration, boiling detection can be performed more finely. In the above-mentioned embodiment, the electric power at the time of double heating is changed by time control. However, another structure may be used as long as the average electric power of the heater 6 is changed, and the heater 6 at the time of double heating. It is not necessary to make the energization time constant for each time as in the above-described embodiments, and for example, it may be set to be a short time sequentially when heating twice for each heating. In addition, instead of the duty ratio control circuit 84, it is also possible to adopt a configuration in which the output of the heater 6 is reduced by a phase control method, or the like.
Instead of 14, another switching element such as a relay may be used. Further, in the above-described embodiment, the case where only the normal rice cooking operation is performed has been described. However, in addition to this, other rice cooking functions such as rice porridge cooking and brown rice cooking may be added.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings. For example, each functional part shown in FIG. 1 as hardware may be replaced by a program of a microcomputer. The present invention can be variously modified and implemented without departing from the scope of the invention.

[Effects of the Invention] According to the present invention, as is clear from the above description, the boiling state of water in a pot can be detected extremely accurately regardless of the amount of cooked rice. It is excellent in that it is possible to accurately control rice cooking based on the detection result, and even if the boiling state is once erroneously detected for some reason, the re-detection operation of the boiling state can be performed more accurately thereafter. It has a great effect.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a block diagram of an electrical configuration, Fig. 2 is a side view showing a partially cutaway view of a rice cooker, and Fig. 3 is a pan temperature and heater output. Change characteristic diagram,
FIG. 4 is a timing chart showing the output waveform of each part in FIG. 1, FIG. 5 is a change characteristic diagram of pot temperature and heater output in a state different from that of FIG. 3, and FIG. 6 is the same as FIG. 3 is a timing chart showing output waveforms of respective parts in FIG. 1 in different states. In the figure, 1 is a rice cooker body, 5 is a pan, 6 is a heater (heating means), 7 is a heat-sensitive cap, 9 is a thermistor, 10 is a pan switch, 13 is a control circuit, 25 is a temperature detecting means, and 83 is a heater drive. Reference numeral 84 is a duty ratio control circuit, 101 is a start switch, 102 is a stop switch, 126 is a time measuring means, 127 is a rice cooking amount detecting means, 128 is a boiling detecting means, 129 is a correcting means,
130 is a double cooking control means, 131 is a boiling detection compensation means, 137
Is a heater output control means (heating output control means), and 138 is a rice cooking end control means.

Claims (1)

[Claims] 1. A temperature detecting means for outputting a temperature detecting signal according to the temperature of a pot, a time measuring means for outputting a time signal indicating an elapsed time during a rice cooking operation, and a rice cooking amount signal according to a rice cooking amount. The cooking amount detecting means and the time series gradient of the pot temperature are measured based on the temperature detection signal and the time signal, and when the measured temperature gradient is equal to or lower than a preset target temperature gradient, the inside of the pot Boiling detection means for determining that the water is in a boiling state and outputting a boiling detection signal, heating output control means for reducing the output of the heating means for cooking rice when the boiling detection signal is output, and this heating The output control means outputs the erroneous boiling detection signal when the temperature detection signal decreases by a predetermined temperature range or more after the output of the heating means is reduced, and the boiling detection means is restarted. A boiling detection compensating means for returning said heating output controlling unit to the initial state, the boiling detection means,
The target temperature gradient is changed so that the target temperature gradient becomes smaller as the rice cooking amount indicated by the rice cooking amount signal increases, and the target temperature gradient is reset to a larger value when the rice boiling amount is restarted. Rice cooker characterized by having.