JPS6216718A - Rice cooker - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a rice cooker that outputs a boiling detection signal of 1 W when water in a pot reaches a boiling state, and uses this boiling detection signal for rice cooking control. Concerning vessels.

[Technical background of the invention and its problems] In recent years, rice cookers have various types of rice cooking control, specifically, for example, when preparing white rice, the water in the pot boils U*-V. (By generating heat with a high output from the rice-cooking heater, it satisfies the so-called "medium-dish" condition, which is one of the well-known conditions for cooking rice deliciously, and reduces the heater output after boiling.) Controls the rice to cook deliciously by preventing the rice from burning, or reduces the peak output for rice cooking after the water in the pot boils when cooking porridge to prevent boiling over. However, in order to perform such control, it is necessary to detect whether the water in the pot has reached a boiling state.However, in conventional rice cookers,
The most common method is to detect the temperature of the pot and determine that it is boiling when the detected temperature rises to a predetermined limit.In this case, the boiling state can be accurately detected. In order to achieve this, it is desirable to set the above group 1% temperature near 100'C. However, when the upper limit temperature is set close to 100'C, the contact state between the temperature sensor section for detecting the pot temperature and the pot, the variation in the circuit constant of the temperature sensor section, and its characteristics. Due to aging, changes in atmospheric pressure, and fluctuations in the boiling point due to the addition of seasonings to the pot when making cooked rice, the temperature may rise even though the pot is boiling. The boiling state may not be detected no matter how long it takes, and in reality, the upper limit temperature is set at around 80°C in anticipation of such fluctuations.For this reason, conventional rice cookers ,
There is a problem in that the detection of the boiling state in the pot becomes extremely inaccurate, and as a result, the rice cooking cannot be controlled accurately.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and its object is to be able to detect the boiling state of water in a pot extremely accurately regardless of the amount of rice cooked in the pot; A rice cooker that can accurately control rice cooking based on the detection results, especially a rice cooker that can automatically adjust the cooking temperature according to the length of boiling duration, which varies depending on the amount of rice cooked and other factors. To provide a rice cooker that is effective in producing delicious rice.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention determines that when a temporal temperature gradient of the pan temperature becomes below a predetermined target temperature gradient, this is determined to be a boiling state and a boiling detection signal is sent. a boiling detection means for outputting the boiling detection signal; and a heater power-off means for cutting off power to the rice-cooking heater when the level of the temperature detection signal reaches a set cooking temperature; Providing correction means for measuring the time until the boiling state in the pot ends and correcting the cooking temperature so that the longer the time obtained by the measurement, the higher the cooking temperature is set in the heater power-off means; The boiling detection means is configured to change the target temperature gradient so that the larger the amount of cooked rice detected by the rice cooking amount detection means is, the smaller the target temperature gradient becomes.

[Embodiments of the Invention] A first embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

In Fig. 2, 1 is the main body of the rice cooker consisting of an inner frame 2, an outer frame 3, etc., 4 is a lid, 5 is copper removably housed in the inner frame 2, and 6 is a device for heating the pot 5. This is a rice cooking heater with a rated output of 600 watts, for example, installed in the space between the bottoms of the inner frame 2 and the outer frame 3. Reference numeral 7 denotes a heat-sensitive cap that is arranged so as to be able to move up and down so as to penetrate through the bottom of the inner frame 2.
It is biased in the F direction, and is arranged in a direction J that presses against the outer bottom of the pot 5 while the pot 5 is housed in the inner frame 2. Reference numeral 9 denotes a thermistor, for example, a thermistor as a heat-sensitive element provided in the heat-sensitive cap 7 to detect the temperature of the pot 5;
is a pot switch for preventing dry cooking that is pressed by a heat-sensitive cap 7 only when the steel 5 containing rice and water is housed in the inner frame 2. Further, 11 is an operation panel installed on the side of the rice cooker main body 1, and 12 is a case installed on the outer bottom of the rice cooker main body 1. Inside this case 12, there is a temperature detected by the thermistor 9 and an operation panel 11.
A control circuit 13 for controlling power on/off of the heater 6 based on input from the heater 6 is housed therein.

FIG. 1 shows the configuration of the -LH control circuit 13 and its related parts that are directly related to the gist of the present invention, which will be described below.

In FIG. 1, the control circuit 13 is shown as hardware by combining various functional parts; however, the present invention is not limited to this, and each of the above functional parts may be replaced by a program of a micro combi coater. Of course.

In FIG. 1, reference numeral 14 denotes a switching element, for example 1 to 1, which is connected between both terminals of an AC power source 5 via the heater 6 and the pot switch 1o in series. Reference numeral 16 denotes a photocoupler consisting of 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 a diode 17 and a resistor 18.

19 is a DC constant voltage circuit that receives the output of the AC power supply 15;
Power is supplied to each circuit section described below from the output lines la and 1b.

Reference numeral 20 denotes an initialization circuit consisting of, for example, a differential circuit, which generates an initialization pulse P every time the power is turned on. Output. 21 is a waveform shaping circuit that shapes the outputs of the E1 to coupler 16 (voltage output corresponding to the half-wave output of the AC power source 15) into a rectangular wave;
2 is a first circuit which divides the output of this waveform shaping circuit 21 to generate a time signal, for example, a clock pulse P1 with a period of 1 second.
The frequency dividing circuit 23 is a second frequency dividing circuit which divides the frequency of the clock pulse P1 and outputs a clock pulse P2 having a cycle of 10 seconds, which is also a time signal. 24 is an 8-0 converter which together with the thermistor 9 constitutes the temperature detection means 25, which outputs a digital temperature detection signal Sd corresponding to the temperature of the pot 5 detected by the thermistor 9. 26 and 27 are first and second temperature value storage units that store values corresponding to temperatures used to detect rice cooking, such as 70°C and 80°C, respectively; 28 is a predetermined lower limit temperature, such as 90°C;
a third temperature value storage unit storing numerical values corresponding to 2;
Reference numeral 9 denotes a fourth temperature value storage section which stores a numerical value corresponding to, for example, 110° C., which is the end-of-life temperature. Also, 30
Numerals 39 to 39 are fifth to fourteenth temperature value storage sections, in which, as shown in FIG. 1, for example, the following numerical values are stored. That is, the fifth temperature value storage section 3o
The numerical value corresponding to 2°C is stored in the 6th. The eighth and eleventh temperature value storage units 31, 33 and 36 each have a temperature of 3°C.
Numerical values corresponding to 1° C. are stored in the seventh and tenth temperature value storage units 32 and 35, respectively, and numerical values corresponding to 1°C are stored in the ninth and twelfth temperature value storage units 34 and 37, respectively. A numerical value corresponding to 5°C is stored, a numerical value corresponding to 112°C is stored in the thirteenth temperature value storage unit 38 as the heater power-off temperature Dz, and a numerical value corresponding to 112°C is stored in the 1st/I temperature value storage unit 39. A value corresponding to 103° C. is stored as the heavy cooking heating start temperature Dr. Reference numerals 40 and 41 denote first and second time value storage units that store numerical values corresponding to, for example, 2 minutes and 4 minutes, respectively, which are used as standards when detecting rice cooking. Reference numerals 42 to 51 denote third to twelfth time value storage sections, in which, as shown in FIG. 1, for example, the following numerical values are stored.

That is, the third time value storage section 42 stores a numerical value corresponding to 7 minutes, the fourth time value storage section 43 stores a numerical value corresponding to 9 minutes, and the fifth and eighth time value The storage units 44 and 47 respectively store numerical values corresponding to 0 seconds, the sixth and ninth R darkness value storage units 45 and 48 respectively store numerical values corresponding to 10 seconds, and the seventh and tenth R darkness value storage units 45 and 48 store numerical values corresponding to 10 seconds, respectively. The time value storage units/46 and 49 each store a value corresponding to 20 seconds, and the eleventh time value storage unit 50 stores a value corresponding to 30 seconds as the double cooking heating reference time N. , 12th
15 as the uneven driving time M is stored in the time value storage unit 51.
The numerical value corresponding to the minute is memorized.

Reference numerals 52 to 64 are comparison circuits, which output a high level signal from the output terminal C when each input value to the input terminals A and B is in the relationship A≧B, and output a high level signal from the output terminal C when the relationship is A<8. Outputs a low level signal from. Further, 65 is a comparison circuit equipped with an enable terminal En, which performs the same operation as the above-mentioned comparison circuits 52 to 64 only when a high level signal is received at the respective enable terminal gn, and the low level signal is applied to the enable terminal En. When receiving a signal, it always outputs a low level signal from output terminal C. 66 and 67 are subtraction circuits which subtract the input value to input terminal E from the input value to input terminal I, and output the subtraction result from output terminal F. Addition circuits 68 to 71 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. 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, and the count contents are initialized when a pulse signal is received at the reset terminal R. ing. Reference numerals 76 to 7 indicate trigger circuits 1 to 7, which output a trigger pulse P3 when the input signal thereof rises. 80 is a delay circuit, which delays the input signal for a short time and outputs it. 81 is a shift register having, for example, 24 unit registers;
This means that every time a pulse signal is received at the clock terminal φ, the input to the data terminal is sent to the first unit register 81a.
At the same time, when new data is read in, the old stored data is sequentially shifted to the upper unit register, and when a pulse signal is received at the reset terminal R, the Initialize stored data J: Initialized. In the shift register 81, the 12th unit register 81b, the first
The eighth unit register 81C1 is configured to output each stored data of the 24th unit register 81d. Reference numeral 82 denotes a memory circuit, which is initialized upon receiving a pulse signal at its reset terminal R, and is configured to store the value input for the first time to the input terminal from this initialized state. being done. 83 is a heater drive circuit which outputs a gate signal S(I) and applies it to the gate terminal of the triac 14 only when it receives a high level signal; 84 is a heater output control circuit which is driven only when it receives a high level signal; This heater output control circuit 84 outputs, for example, a pulse-like control signal SC with a duty ratio of 50% when it is driven. Reference numerals 85 to 100 are transfer gates, and these receive high-level signals at terminals 1 to 1. It becomes conductive only when it is in a closed state.

101 and 102 are stars for starting rice cooking provided on the operation panel 11, respectively! - A switch and a stop switch for stopping rice cooking. These are composed of momentary type push button switches, and only when turned on, output pulse signals (high level signals) P4 and P5 to the corresponding lines, respectively. Also, 103 to 105 are R-S
Flip-flops, 106 to 115 are AND circuits, 1
16 to 118 are OR circuits, and 119 to 125 are inverters. In addition, 1st. A clock means 126 is constituted by the second frequency dividing circuit 22° 23 and the AND circuit 108,
1st. The second temperature value storage unit 26°27, the first . Second time value storage unit 4.0, 41. Comparison circuits 52, 53, 56,
57. The counter 72° AND circuits 106, 109 and the inverter 119° 120 are used to cook tf! n detection means 1
27, and a fifth temperature value storage section 30. Comparison circuit 6
5. By subtraction circuit 66, shift register 81 and transfer gates 85, 86, 87? #Top detection means 12
8 is configured, and a fourth temperature value storage section 29.8 is configured. 3rd degree fourth time value storage unit 4.2, 43. Comparison circuit 58.59, counter 73. AND circuits 107, 110 and impark 1
21 and 122 constitute a correction means 129, and the first
/If7) Temperature value storage unit 39° Fifth to twelfth time value storage units 4/I to 51. Comparison circuits 62, 63, 64. Addition circuits 70, 71° counters 74, 75.1 to trigger circuits 78, 79. Transfer game-1-95-100
．． The AND circuits 114, 115 and the inverter 125 constitute a double cooking control means 130Δ, and the seventh to thirteenth temperature value storage units 32 to 38. The comparison circuit 61° addition circuit 68, 69.1 to the transfer gates 89 to 94 and the R-S flip 70 knob 105 constitute a heater power cutoff means 130B, and the sixth temperature value storage section 31
．． Comparison circuit 60. Boiling detection compensation means 13 by subtracting circuit 67, memory circuit 82 and 88 to 1 Heransfagu-1
1 is configured.

Next, the operation of the above structure will be explained with reference also to FIGS. 3 and 4. Incidentally, FIGS. 3A and 3B show the temperature detected by the thermistor 9 (that is, the temperature of the pot 5) and the time change characteristics of the output of the heater 6, respectively, and FIG.゜53.54..55,60,61.
62,63.64,. 65. Heater output control circuit 84.
Start switch 101. R-S flip-flop 10
3°104.105 each set output terminal Q, AND circuit 106, 107, 113, 115. Each output waveform from the OR circuit 118 is shown in association with its respective sign.

That is, when the pot 5 containing rice and the required amount of water is stored in the inner frame 2, the steel switch 10 is turned on in response 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 circuit 2
Initialization pulse P from 0. is output, this initialization pulse PO causes the R-S flip-flop 103 to
is reset and a high-level signal is output from its reset output terminal 0, and this high-level signal initializes the counters 72 and 74 and the memory circuit 82, and
R-S flip-flop 105 is reset. Also, at this time, the trigger pulse P3 is output from the trigger circuit 76 which receives the high level signal from the R-S flip-flop 103 via the OR circuit 117.
The shift register 81 is initialized by the trigger pulse P3, and the R-S flip-flop 104 is reset by the high level signal outputted via the OR circuit 117 as well. After this, time t. When the start switch 101 is turned on (see Figures 3 and 4), the R-S flip-flop 103 is set by the pulse signal P4 output in response to the turn-on, and the output from the set output terminal Q is set. High level signal is AND circuit 1
It is given to 12°113. At this time, one of the AND circuits 112 has R-
Since the low level signal from the set output terminal Q of the S flip-flop 104 is given, its output remains a low level signal, but the other AND circuit 113 has 1~Output terminal Q
Since the low level signal from the R-S flip-flop 105 is inverted to a high level signal by the inverter 124, and the high level signal from the reset output terminal Q of the R-S flip-flop 105 which is also in the reset state is applied. As a result, a high level signal is output from the AND circuit 113 and applied to the heater drive circuit 83. Therefore, the gate signal Sg is output from the heater drive circuit 83 to turn on the triac 14, and in response, the AC power supply 15 outputs the gate signal Sg to the pot switch 10. Electricity is applied to the heater 6 via the triac 14 to heat the pot 5, and the rice cooking process begins. As the rice cooking process progresses, the temperature of the steel 5 rises as shown in FIG. 3, and the temperature detection circuit 25 outputs a temperature detection signal Sd corresponding to the temperature of the steel 5. Then, when the temperature of the steel 5 rises to 70° C. stored in the first temperature value storage section 26 (time t1), the rice cooking □□□ detection section 127 operates first. That is, in the cooked rice amount measuring section 127, the comparison circuit 52
, the temperature detection signal @Sd input to the terminal △ is the terminal B
70 inputted from the first temperature value storage unit 26 for
A low level signal is output until time t1 when the temperature value becomes equal to the temperature value corresponding to °CJ, and a high level signal is output after that time t1. Further, the comparison circuit 53 is configured such that the temperature detection signal Sd input to the terminal B of A is second to the terminal A.
A high level signal is output until time t2 when the temperature value becomes larger than the temperature value corresponding to r 80 'CJ input from the temperature value storage unit 27, and a low level signal is output after that time t2. Therefore, time 1. A high level signal is output from both comparison circuits 52 and 53 only during the period of ~1:2.
Since it is applied to the D circuit 106, the pulse signal P1 with a period of 1 second from the first frequency dividing circuit 22 is ANDed only during this period.
The clock terminal CK of the counter 72 passes through the circuit 106.
given to. Therefore, as a result, the first count of the counter 72 becomes a value corresponding to the time Ta (time from time t1 to t2) required for the temperature of the pot 5 to decrease from 70°C to 80°C.

Therefore, the time Ta measured as described above 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 the count value of the counter 72 corresponding to this time Ta. That is, the count value of the counter 72 is stored in the first and second time value storage sections 40.4 by the comparison circuit 56.57.
1 (corresponding to 2 minutes and 4 minutes) 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 value equivalent to 2 minutes (in other words, when the amount of rice cooked is relatively small), and this low level signal is sent to the inverter 119 to cook the rice. The signal is inverted to a high level signal, which is a quantity signal, and is applied to line L1. Furthermore, the comparison circuit 57 outputs a high level signal as a rice cooking amount signal and supplies it to the line L3 when the count value of the counter 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). 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 rice cooked is medium), a high level signal is output from the comparator circuit 56, and this is ANDed. A low level signal is applied to one input terminal of the circuit 109, and a low level signal is output from the comparison circuit 57, which is inverted to a high level signal by the inverter 120 and applied to the other input terminal of the AND circuit 109, resulting in the following. The AND circuit 10
A high level signal which is a rice cooking amount signal is outputted from 9 and given to line 12. In short, the rice cooking amount detection unit 127 determines the amount of rice to be cooked based on the time required for the temperature of the pot 5 to rise from 70°C to 80°C, and the rice cooking amount signal (high level signal) to line Lz
, L2, and l-3.

When the detected rice cooking amount is relatively small, the transfer gates 1 to 85, 89.95 whose gate terminals are connected to the line L1 are in a conductive state, and the detected rice cooking amount is medium. If the gate terminal is connected to line 1-2
The transfer gates 86, 90.96 connected to the line L3 are in a conductive state, and if the detected amount of cooked rice is relatively large, the transfer gates 87, 91.97 whose gate terminals are connected to the line L3 are in a conductive state. It becomes like this.

At this time, the seventh. 8th. 9th
The temperature values stored in the temperature value storage units 32, 33, and 34 are for adjusting the heater power-off temperature Dz (the temperature value stored in the thirteenth temperature value storage unit 38, that is, 112°C). Each of these stored temperature values is selectively given to the input terminal Y of the adder circuit 68 according to the magnitude of the detected rice cooking amount, and the adder circuit 68 receives the temperature value input in this way. It is added to the numerical value (heater power-off temperature Dz) stored in the thirteenth temperature value storage section 38 and output. Also,
Similarly, the fifth. The time value stored in the 6th and 7th time value storage units 4.4.4! 5.46 is the double cooking heating reference time N (the 11th time value storage unit 5).
0 (ie, 30 seconds), and each of these stored time values is selectively given to the input terminal Y of the adder circuit 70 depending on the magnitude of the detected rice cooking amount. In the addition circuit 70, the time value input in this manner is added to the value stored in the eleventh time value storage section 50 (once cooked heating time η1 (time N)) and output.

After this, when the temperature of the pot 5 further increases and becomes higher than the lower limit temperature of 190°C stored in the third temperature value storage section 28 (
At time t3), each input value of the pair of input terminals Δ and B of the comparator circuit 54 has a relationship of A≧B, and the output of the comparator circuit 54 is inverted to high level No. 13. As a result, the AN that receives the above high level signal at one input terminal
The D circuit 108 allows passage of the opposite input to the other input terminal, that is, the pulse signal P2 with a period of 10 seconds from the second frequency dividing circuit 23 in the timer 126, and also A comparison circuit 65 receives the high level signal from the comparison circuit 54 via a delay circuit 80 to an enable terminal En.
becomes operational, and in response, the boiling detection means 12
The boiling detection means No. 8 is now enabled. That is, when the pulse signal P2 passes through the AND circuit 108, the pulse signal P2 is applied to the clock terminal φ of the shift register 81, so that the shift 1 to register 81 are connected to the data terminal φ. The input to the temperature detection signal 3d, that is, the temperature detection signal 3d, is read and stored every 10 seconds, and each time a new temperature detection signal Sd is read, the old temperature detection signal Sd is sequentially shifted to the upper unit register. As a result, the 12th unit register 811) has the following information:
The temperature detection signal Sd 120 seconds (2 minutes) before the current temperature detection signal 3d is stored, and the 18th unit register 81c stores the temperature detection signal Sd 180 seconds (2 minutes) before the current temperature detection signal Sd.
3 minutes) previous temperature detection signal Sd is stored, and the current temperature detection signal Sd is stored in the 24th unit register 81 (I).
The temperature detection signal Sd from 240 seconds (four cycles ago) is stored. At this time, the unit registers 81b and 8
The stored data 1c and 81d are sent to the subtraction circuit 66 via corresponding transfer gates 85, 86 and 87, respectively.
However, as mentioned above, when the number of times the rice is cooked is relatively small, the gates 1 to 85 are in a conductive state, and the unit register 81 is in a conductive state.
The stored data of 1) is given to the input terminal E of the subtraction circuit 6G, and similarly, when the amount of cooked rice is medium or relatively large, each stored data of unit registers 810 and 81 (I is subtracted). The temperature detection signal 3d is directly input to the other input terminal of the subtraction circuit 66, so that the subtraction circuit 66 receives the current temperature detection signal. The value shown by the temperature detection signal Sd 2 minutes ago, 3 minutes ago, or 4 minutes ago, which corresponds to the reference time in the embodiment of the present invention, is subtracted from the value shown by the signal Sd, and the subtraction result is becomes a clay corresponding to the temperature rise value of the pot 5 and the time-series temperature gradient of the pot 5 within a certain reference time (2 minutes, 3 minutes or 4 minutes). 5, that is, the rate of increase of the temperature detection signal Sd has a property of becoming approximately zero when the water in the pot 5 reaches a boiling state, and therefore, within the reference time (
If it is detected that the temperature rise value of the pot 5 has become equal to or less than a predetermined comparison temperature value, it can be determined whether or not the inside of the steel 5 has reached a boiling state. In this case, -25 = Since the temperature increase rate of the pot 5 has a tendency to become slower as the amount of rice cooked increases, in order to accurately detect boiling, it is desirable to change the above reference time according to the amount of rice cooked, In this embodiment, in order to perform accurate temperature detection, the reference time (i.e., the sampling time of the temperature detection signal Sd) is automatically set to 2 minutes, 3 minutes, or 4 minutes as described above. I am trying to change it to . Then, in the comparison circuit 65, the output from the subtraction circuit 66 (the temperature rise value of the steel 5 within the three-step reference time determined according to the amount of rice cooked) and the fifth temperature value storage section 3o are stored for comparison. The value stored as the temperature value (equivalent to 2°C) is compared, and when the temperature rise value of the pot 5 within the above reference time becomes less than 2°C, the comparison circuit 65 outputs a high level signal. A boiling detection signal Sz consisting of a signal is output (time t4).

Therefore, at the time t4, the storage contents of the storage circuit 82 are in an initialized state, and a numerical value (corresponding to 3° C.) is stored in the sixth temperature value storage section 31 from the stored value.
The output of the subtraction circuit 67 that subtracts is a negative value, and the comparison circuit 60 is in a state of outputting a low level signal. Therefore, both input terminals of the OR circuit 117 are connected to the comparison circuit 6.
A low level signal is applied from the reset output terminal 0 of the 0 and RS flip-flop 103, and this low level signal is inverted to a high level signal by the inverter 123 and applied to one input terminal of the AND circuit 111. There is. Therefore, when the boiling detection signal Sz (high level signal) is output as described above at time t4, AND
A high level signal is output from the circuit 111 and the R-S flip-flop 104 is set. Then, the output of the AND circuit 113, which had been outputting a high level signal, is inverted to a low level signal, and the AND circuit 112 outputs a high level signal.
An R-S flip-flop 103.10/
A high level signal is given from each cellar [~output terminal Q of I] and the reset output terminal Q of the R-S flip 70 knob 105, and a high level signal is output from the AND circuit 112. In response, the heater output control circuit 84 sends a pulsed control signal F"r with a duty ratio of 50%.
Sc is outputted and supplied to the heater and drive circuit 83. As a result, the reactors 1 to 14 are turned on and off at a duty ratio of 50%, and at this time, the rated output of the heater 6 is 600 watts, so the heater 6 has an output of 300 watts, which is half the rated output. I start to get a fever. Further, when the R-S flip-flop 104 is set to 1~ at the above-mentioned time t4, the trigger circuit 77 is driven and the trigger pulse P3 is outputted from now on, so that the trigger pulse P3 causes the counter 7 to
3 is initialized, the transfer gate 88 becomes conductive, and the temperature detection signal Sd at time 1-4 (corresponding to the temperature of the pot 5 at the time of detection of the boiling state) is stored in the memory circuit. 82. Also, at this point, there is still enough water left in the pot 5 and its temperature does not exceed 100°C, so the temperature detection signal Sd corresponding to the temperature of the pot 5 and the fourth temperature value memory are stored. Boiling end temperature stored in section 29 (equivalent to 110°C)
The comparator circuit 55 outputs a high level signal, and therefore receives the high level signal as well as the high level signal from the reset output terminal Q of the R-87 lip-flop 105. Frequency dividing circuit 22
It is in a state where the passage of the pulse signal P1 (1 second period) from is allowed. Therefore, the values from 1 to 1 of the counter 73 initialized as described above indicate the elapsed time from time t4. Then, as the rice cooking process further progresses and the inside of the steel 5 exhibits a so-called dry-up state, the temperature of the steel 5 will rise sharply. When the temperature reaches 110° C., each input terminal A, B of the comparator circuit 55 becomes A<
Since the output is inverted to a low level signal due to the relationship B, the AND circuit 1Q7 blocks the passage of the pulse signal P1, and the counting operation of the counter 73 is stopped. Therefore, as a result, the count value of the counter 73 is the required time T1 from time t4 when the boiling detection signal Sz is output to time t5 when the temperature of the pot 5 reaches 110°C]
(corresponds to the duration of the boiling state).

Like the time Ta from time t1 to time t12 described above, the time Tb measured as above has the property of increasing or decreasing in proportion to the amount of rice cooked, and is also influenced by the ratio of rice to water during cooking. The correction means 129 corrects the rice cooking amount detected by the rice cooking amount detection means 127 as follows based on the count value of the counter 73 corresponding to the time Tb.

That is, the values of the counter 73 from 1 to 1 are calculated by the comparator circuit 58.5.
3rd by 9. It is compared with each numerical value (corresponding to 7 minutes and 9 minutes) stored in the fourth time value storage units 42 and 43, respectively.

At this time, the comparator 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 rice cooked is relatively small), and this low level signal is turned to a high level by the inverter 121. It is inverted to a level signal and applied to line L4. Further, the comparison circuit 59 outputs a high level signal and supplies it to the line L6 when the count operation of the counter 73 is equal to or greater than the value equivalent to 9 minutes (in other words, when the amount of cooked rice is relatively large). -30- Then, when the value of call 1 of the counter 73 is equal to or greater than the value equivalent to 7 minutes and smaller than the value equivalent to 9 minutes (in other words, when the amount of rice cooked is medium), a high level is output from the comparator circuit 58. A signal is output and applied to one input terminal of the AND circuit 110, and a low level signal is output from the comparison circuit 59, which is inverted to a high level signal by the inverter 122 and applied to the other input terminal of the AND circuit 110. As a result, a high level signal is output from the AND circuit 110 and applied to the line L5. When the amount of cooked rice detected in this way is relatively small, the gate terminals 1 to 1 to 92.98 whose gate terminals are connected to the line L4 are brought into conduction quickly, and the detected amount of cooked rice is medium. In this case, 93.99 becomes conductive to transfer game 1 whose gate terminal is connected to line L5,
Furthermore, when the detected amount of cooked rice is relatively large, the gate terminals are connected to lines 1-6 and 1-94.
, 100 become conductive. At this time, the transfer gate 92 is selectively turned on as described above.
, 93.94 corresponding to the 10th. The temperature values stored in the 11th and 12th temperature value storage units 35, 36, and 37 are also the same as the heater power-off temperature Dz (the temperature value stored in the 13th temperature value storage unit 38, that is, 112°C). These stored temperature values are selectively given to the input terminals Y of the six adder circuits according to the length of the time Tb, and the six adder circuits input the temperature values in this way. The temperature value is added to the numerical signal from the adding circuit 68 (that is, the temperature value corresponding to the amount of cooked rice detected by the rice amount detection circuit 127 with respect to the temperature value DZ for heater power-off). The temperature value added by the rice cooking amount detection unit 127 and the detected rice cooking amount are corrected.

In addition, 1 to 1 to 1 to 1, which are also selectively conductive,
-8th corresponding to 98, 99, 100. 9th. The time values stored in the tenth time value storage unit 4.7.48.49 also include the double cooking heating reference time N (the eleventh time value storage unit 5).
0, i.e., 30 seconds), and each of these stored time values is selectively given to the input terminal Y of the adder circuit 71 according to the length of the time Tb, In the addition circuit 71, the time value input in this way is converted into a numerical signal from the addition circuit 70 (i.e., the magnitude of the amount of cooked rice detected by the amount of cooked rice detected by the amount detection circuit 127 with respect to the double cooking heating reference time N). (a time value corresponding to the amount of rice added), and thereby acts to correct the added time value by the rice cooking amount detection section 127, and thus the detected rice cooking amount.

Now, at subsequent time t6, the rice cooking amount detection unit 127 determines that the temperature of the steel 5 is the cooked rice temperature corresponding to the output from the adder circuit 69 (i.e., the heater power-off temperature DZ (112°C)). When the temperature reaches the temperature value obtained by adding the temperature value corresponding to the detected rice cooking amount and the corrected temperature value by the correction means 129, the comparison circuit 6 in the heater power-off means 130B
Since the input values to the input terminals A and B of 1 are in the A2B relationship and a high level signal is output from the comparator circuit 61, the R-S flip-flop 105 is set to 1-. Then, the low level signal from the reset output terminal d of the R-S flip-flop 105 is output to the AND circuit 112.
Since the output of the AND circuit 112 is inverted to a low level signal, the heater output control circuit 84 is stopped, and in response, the heater drive circuit 83 stops outputting the gate signal Sg. is maintained in a turned-off state, that is, the heater 6 is cut off,
The rice cooking process is then completed. And at this time, R-
A high level signal from the set output terminal Q of the S flip-flop 105 is given to AND circuits 114 and 115, and the AND circuit 114 allows the pulse signal P1 to pass, and in response, double cooking control is performed. Means 13
0B will function and shift to uneven stroke. In short, the temperature of the steel 5 is the temperature value (7th, 8th, 9th temperature value) corresponding to the amount of cooked rice detected by the rice cooking amount detection means 127 with respect to the heater power-off temperature [) or 112°C. Any one of the temperature values stored in the storage units 32, 33, 34) and the corrected temperature value by the correction means 129 (any one of the temperature values stored in the 10th, 11th, 12th temperature value storage units 35, 36, 37) When the rice reaches the finished cooking temperature obtained by adding any one of the temperature values, the rice cooking process is completed and the process moves to the shading process, and the operation in this shading process will be described below in d3. In the case of this embodiment, the above-mentioned cooking temperature is stored in the seventh to thirteenth temperature value storage units 32 to 38.
The temperature varies between 114°C and 122°C depending on the stored contents.

The counter 75 in the double-cooking control means 130B has been counting the pulse signal P1 since the power was turned on, and therefore, the value of the next column 1 is at least the number output from the adding circuit 71 at time 1.6. 1 direct signal (in this embodiment, the maximum value corresponds to 100 seconds), and as a result, each input value to input terminals A and B of the comparator circuit 64 has a relationship of A<B. , the comparison circuit 64 outputs a low level signal. In addition, in the double cooking control means 130 (Pursen counter 74 starts from time t6 until 1st).
~ Since the operation is started, at this point, the respective numerical values input to the input terminals A and B of the comparator circuit 62 are in the A2B relationship, and a high level signal is output from the comparator circuit 62. Then, when the heater 6 is cut off at time t6, the temperature of the steel 5 gradually decreases after being overcoated as shown in FIG.
At time t7, the temperature of 8!5 is the 14th temperature value storage unit 39.
Double cooking start temperature Dr (103°C) stored in
), each input value to the input terminals A and B of the comparator circuit 63 has a relationship of A2B and a high level signal is output. The counter 75 is initialized by the trigger pulse P3. Then, each input value of the input terminals A and B of the comparison circuit 64 becomes in the relationship A2B, and a high level signal is output from the comparison circuit 64, and in response, a high level signal is output to all input terminals of the AND circuit 115. Given a signal, its A
The output of the ND circuit 115 is inverted to a high level signal. As a result, the heater drive circuit 83, which has received the high level signal from the AND circuit 115, turns off the lights 1 to 14 and re-energizes the heater 6, and in response, double heating is performed. It will be done. At this point, the count value of the counter 75 indicates that the temperature of the steel 5 is 10.
It now shows the elapsed time from time t7 when the temperature dropped to 3°C, and at time t8 the count value corresponds to the output from the adder circuit 71 (i.e., the reference time N (30 seconds) for double cooking heating). , when the comparator circuit 6
Since the input values for the input terminals A and B of 4 are in the relationship A<B, and the output of the comparison circuit 64 is inverted to a low level signal, the output of the AND circuit 115 is also inverted and the output of the heater drive circuit 83 is inverted. starts to turn on the triac 14, thereby cutting off the power to the heater 6 and stopping the double cooking heating. After this, at each time ta and tx 1 when the temperature of the pot 5 rises once due to double cooking heating and then decreases to 103°C, the heater 6 is energized again in the same manner as described above to perform double cooking heating. , In such double cooking heating, the count value of the counter 75 is added to the addition circuit 71.
It is stopped at each time TIO, t12, at which time has elapsed to correspond to the output from. Then, at time t13 when the erratic driving time M (15 minutes) stored in the twelfth time value storage section 51 has elapsed after time t6, the count value of the counter 74 becomes a value corresponding to the erratic driving time M. Since the output of the comparator circuit 62 is inverted to a low level signal, the state in which the AND circuit 115 outputs a low level signal and the heater drive circuit 83 is maintained in a state where its operation is stopped, resulting in an uneven process. is terminated.

Then, when the output j of the comparison circuit 62 is inverted to a low level signal as described above, the output of the inverter 125 is inverted to a high level signal and the trigger pulse P3 is output from the trigger circuit 79. The R-S flip 70 knob 103 is reset by P3, and from this point on, the process shifts to a heat retention process using a heat retention heater (not shown).

In summary, in the uneven process, the heater 6 is re-energized when the temperature of m5 drops to 103°C, which is the double-cooking starting temperature [)r, and the energization time is set to the standard double-cooking heating time. A time value (5th.
6th. Any one of the time values stored in the seventh time value storage unit 4-4, 45, 46) and the corrected time value by the correction means 129 (8th, 9th, 10th time value storage unit 47°) 48. When the time value (one of the time values stored in 4.9) is added, the heater G is turned off and the double heating is terminated.
In the case of this example, the heating time for two-sided cooking is from the fifth to the first.
30 depending on the memory contents of the time value storage units 44 to 50 of 1.
It varies between seconds and 70 seconds.

So far, we have described the effect when the temperature of the pot 5 continues to rise without falling after the boiling detection signal S7 is output at time t4 and the output of the heater 6 is reduced to half of the rated value. However, in the following, after dropping the protrusion of heater 6, steel 5 is
The effect when the temperature decreases will be explained with reference to FIGS. 5 and 6, which are similar to FIGS. 3 and 4, respectively. That is, the phenomenon in which the temperature of the steel 5 decreases when the output of the heater 6 is reduced by half occurs when the water in the pot 5 has not yet boiled (in other words, when the boiling detection signal SZ is erroneously output). Such a phenomenon can occur, for example, when seasonings such as soy sauce poured into the pot 5 burn on the bottom of the steel 5 when making cooked rice, causing the water in the pot 5 to burn. It is believed that this is caused by an increase in the gap between the temperature and the temperature detected by the thermistor 9. Therefore, when the output of the heater 6 is halved at time 1-4 in FIGS. 5 and 6, the temperature of the chain 5 at that time (i.e., the boiling detection means 128 A temperature detection signal Sd corresponding to the temperature of the steel 5 when the steel 5 is detected to be in a boiling state is stored in the storage circuit 82 in the boiling detection compensating means 131. At this point, boiling detection compensation means 131
The subtraction circuit 67 subtracts the value stored in the sixth temperature value storage section 31 (equivalent to 3° C.) from the value stored in the storage circuit 82, and compares the temperature value Tp corresponding to the subtraction result. It is applied to input terminal A of circuit 60. After this IC, when the temperature of the steel 5 drops to the above temperature value Tp (time j4m), the output of the comparison circuit 60 is inverted to a high level signal, and in response to this, the R-S flip-flop 104 is reset to 1, the trigger circuit 76 is driven, and the trigger pulse P from the 1 to trigger circuit 76 is driven.
3 initializes the shift register 81. Therefore, 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, so that a high level signal is continuously given to the heater drive circuit 83. Accordingly, the heater 6 generates heat at the rated output, that is, 600 watts.

Further, in response to the shift register 81 being initialized as described above, the boiling detection means 127 starts to perform the same boiling state detection operation as described above, and for example, at time t42, the boiling detection signal S7 is sent from the comparator circuit 65. is output, the output of the heater 6 is halved again. Also,
If the temperature of the steel 5 decreases again after this, the same operation as described above is repeated, and in this manner, the boiling knee detection compensation means 131 makes the detection operation of the boiling detection means 128 more accurate. functions.

According to the present embodiment described above, the following effects can be achieved. That is, instead of detecting the boiling state of the water in the pot 5 based on a predetermined absolute upper limit temperature as in the conventional method, the boiling state of the water in the pot 5 is detected when the water in the steel pot 5 quickly reaches a boiling state. (specifically, the amount of change in the temperature of the steel 5 within a predetermined reference time is a constant comparison temperature value stored in the fifth temperature value storage section 30). (2°C) or below), the contact state between the heat-sensitive cap 7 and the bottom of the heat-sensitive cap 15, the thermistor 9 or the A-D converter constituting the temperature detection means 25. Even if there are variations in the circuit constants of 24 and changes in its characteristics over time, changes in atmospheric pressure, or fluctuations in the boiling point due to seasonings being put into the pot 5 when making cooked rice, the steel It is possible to accurately detect the boiling state of the water inside the boiler. In addition, when detecting the boiling state in this way, the temperature rise gradient of the pot 5 changes depending on the amount of rice cooked, so the boiling detection as described above may be inaccurate when the amount of rice cooked differs. However, in this embodiment, the temperature gradient of the target steel 5 is changed at the time of boiling detection depending on the amount of cooked rice detected by the rice cooking amount detection means 127 (specifically, the temperature gradient is changed). (Configuration that changes the reference time required when measuring)
Therefore, the boiling state of the water in the pot 5 can always be accurately detected even when the amount of rice cooked is different. In this embodiment, the rice cooking control is performed by causing the heater 6 to generate heat at the rated pressure until a boiling state is detected, and then reducing the output of the heater 6 by half. Since the boiling state is accurately detected, the rice cooking control mentioned above can be performed strictly, which is one of the conditions for deliciously cooking rice.
In addition to being able to fully meet the conditions of "Chu-pappa",
You can cook the rice with less stickiness, and the rice is generally well-cooked! Ru. Roughly speaking, in this embodiment, the larger the amount of cooked rice detected by the rice cooking amount detecting means 127, the more the difference is caused by the disconnection of the heater 6 when a relatively large amount of unnecessary moisture remains in the steel 5 during dry-up. Since the electric temperature, that is, the temperature at which the rice is cooked, is raised, the rice can be cooked well from this aspect as well. Moreover, in this case, a correction means 129 is provided to adjust the cooking temperature of the -C rice according to the length of the period during which the water in the pot 5 is in a boiling state (that is, the period that varies depending on the size of the amount of rice to be cooked). Since the configuration is configured to perform correction, it is possible to more strictly control rice cooking according to the amount of rice to be cooked and the ratio of rice to water during cooking. Furthermore, the heating time for two-sided cooking during the unevenness process is also changed to a time corresponding to the amount of cooked rice detected by the rice cooking amount detection means 127 and corrected by the correction means 129. It is possible to perform the necessary and sufficient oxidation, making the cooked rice even more delicious. In addition, when making cooked rice, boil detection compensation means 131 is caused by errors in boil detection caused by seasonings such as soy sauce put into #A5 burning.
Since the temperature is compensated for by Even in such a case, the boiling state of the water in the pot 5 can be detected extremely accurately. Furthermore, in each of the above embodiments, the temperature of the steel 5 is the lower limit temperature (
Since the function of the boiling detection means 128 is activated only when the temperature reaches 90° C., the temperature gradient is flat as shown at the time when the temperature of the steel 5 rises, as shown by G in FIG. This eliminates the possibility of erroneously detecting a certain period as a boiling state.

A second embodiment of the present invention is shown in FIG. 7, and only the differences from the first embodiment will be described below. That is, this second embodiment is characterized in that a boiling detection means 132 with a different function is provided in place of the boiling detection means 128 in the first embodiment. The detection means 132 will be described. In the boiling detection means 132, 133 is a shift register having, for example, 12 unit registers, and the data stored in the 12th unit register 133a is applied to the input terminal E of the subtraction circuit 134.

The shift register 133. a subtraction circuit 134 and a comparison circuit 13 receiving the output of this subtraction circuit 134 at input terminal B;
5 is a shift register 81.5 in the first embodiment.
It has the same functions as the subtraction circuit 66 and the comparison circuit 65, respectively. Also, 136, 137, 138 is the 15th
．． 16th. In the seventeenth temperature value storage section, these are respectively 2°C, 1.5°C, and 1.5°C, which are the reference temperatures in the embodiment of the present invention.
A numerical value corresponding to 1°C is stored. Furthermore, 139
．． 1/1.0.141 is the storage unit 136, 137.
Transformer 77 goo 1~ provided corresponding to 138 respectively
So, each terminal from goo 1 to line 1-1, l-2, L3
It is connected to the.

In this embodiment, the temperature detection signal Sd of Kaneka is applied to the input terminal of the subtraction circuit 134, and the data stored in the unit register 133a of the shift 1 to register 133, that is, the data at the time 120 seconds (2 minutes) before The temperature detection signal Sd is given to the input terminal F of the subtraction circuit 134, and therefore the numerical signal given from the subtraction circuit 134 to the input terminal of the comparison circuit 135 is the temperature rise of the pot 5 over a fixed period of 2 minutes. It corresponds to the value. At this time,
Depending on the amount of cooked rice detected by the cooked rice amount detection means 127, any one of the transfer games I to 139 to 141 is in a conductive state, and the 15th. Any one of the stored numerical values in the 16th and 17th temperature value storage sections 136, 137, and 138 is given to the input terminal A of the comparator circuit 135 as the base tii:temperature. Therefore, in the comparator circuit 135, when the input values of input terminals A and B have a relationship of A2B,
In other words, the boiling detection signal SZ consisting of a high level signal is output as soon as the temperature p value of the pot 5 for two minutes becomes - below the old reference temperature.

In short, in this embodiment as well, when the temperature increase gradient of the pot 5 becomes below a predetermined target temperature gradient (specifically, the change in the temperature of the pot 5 within a certain period of time becomes below a predetermined reference temperature). The boiling detection signal Sz is output when the boiling temperature is reached (when the boiling temperature is reached), and the reference temperature is automatically changed depending on the amount of rice cooked, thereby achieving the same effect as in the above embodiment. can.

In each of the above embodiments, the temperature of the pot 5 ranges from 70°C to 80°C.
The rice cooking amount detection means 127 is configured to detect the rice cooking amount based on the time required for the rice to rise to C.
．． The memory value of 27 is not limited to this, and the memory value of pot 5
It is also possible to provide a rice cooking amount detection means of another configuration, such as one that detects the amount of cooked rice by measuring the entire limbs of the rice cooker. Of course, each of the other temperature value storage units 28 to 39, 136 to 138 and the temperature value storage units 40 to 5
The storage contents of No. 1 are also not limited to the above embodiments, and in particular, the numerical values stored in the fourteenth storage section 39 for two-sided cooking heating control may be substituted with the numerical values stored in the storage circuit 82. It's a good thing. Furthermore, in each of the above embodiments, the measurement of the duration of the boiling state by the correction means 129 is performed using the boiling end temperature (1) stored in the two fourth temperature value storage units.
10° C.), but instead of this, the point in time when the temperature of the steel 5 suddenly rises may be detected, and the boiling duration may be measured based on the detection result. Furthermore, in each of the above embodiments, the rice cooking amount detected by the rice cooking amount detecting means 127 is ranked into three levels, but this may be further ranked into multiple levels. boiling detection means 128 or 13
2 and the configuration of the correction means 129 are also changed accordingly, but by having such a configuration, boiling detection can be performed more precisely. In each of the above embodiments, the electric power during double cooking heating is changed by time control. However, other configurations may be used as long as the average electric power of the heater 6 is changed. The energization time of the heater 6 does not need to be constant each time as in each of the above-mentioned embodiments, and may be made to become shorter in sequence during each double-sided heating, for example. In addition, instead of the heater output control circuit 84, a circuit configured to reduce the output of the heater 6 using a phase control method may be adopted, and instead of the triac 14, another switching element such as a relay may be used. You can also do it.

Further, in the above embodiment, only a normal rice cooking operation is described, but it is of course possible to add other rice cooking functions such as porridge cooking and brown rice cooking.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without departing from the spirit thereof.

[Effects of the Invention] As is clear from the above description, according to the present invention, the boiling state of water in a pot can always be detected extremely accurately regardless of the amount of rice being cooked. Rice cooking control based on detection results, for example, boiling temperature that varies depending on the amount of rice cooked and other factors! It is possible to accurately control rice cooking, such as automatically adjusting the temperature at which the rice is cooked, depending on the length of the cooking time, and thereby produce excellent effects such as delicious rice.

[Brief explanation of the drawing]

1 to 6 show a first embodiment of the present invention, in which FIG. 1 is a block diagram of the electrical configuration, FIG. 2 is a partially cutaway side view of the rice cooker, and FIG. The figure is a change characteristic diagram of pan temperature and heater output, Figure 4 is a timing chart 1 to 1 showing the output waveform of each part in Figure 1, and Figure 5 is a diagram of wI humidity temperature and heater in a different state from Figure 3 above. FIG. 6 is a timing chart 1 showing the output waveforms of each part in FIG. 1 in a state different from that in FIG. 4. Also, the seventh
The figure is a diagram corresponding to FIG. 1 showing a second embodiment of the present invention. In the figure, 1 is the rice cooker body, 5 is a pot, 6 is a heater, 7 is a heat-sensitive cap, 9 is a thermistor, 10 is a pot switch, 13 is a control circuit, 25 is a temperature detection means, 83 is a heater drive circuit, and 84 is a Heater output control circuit, 101 a start switch, 102 a stop switch, 126 a clock means, 12
7 is a rice cooking amount detection means, 128 and 132 are boiling detection means,
129 is a correction means, 130A is a double cooking control means, 13
0B indicates heater power cutoff means, and 131 indicates boiling detection compensation means. Applicant: Toshiba Corporation■

Claims (1)

[Scope of Claims] 1. Temperature detection means for outputting a temperature detection signal according to the temperature of the pot, time measurement means for outputting a time signal indicating the elapsed time during rice cooking operation, and a rice cooking amount signal according to the amount of rice cooked. a rice cooking amount detection means that outputs a rice cooking amount, and measures a time-series gradient of the pot temperature based on the temperature detection signal and the time signal, and controls the pot temperature when the measured temperature gradient becomes equal to or less than a predetermined target temperature gradient. a boiling detection means that determines that the water in the rice cooker is in a boiling state and outputs a boiling detection signal; and a heater that cuts off power to the rice-cooking heater when the level of the temperature detection signal reaches a set cooking temperature. A power cut-off means, which measures the time from when the boiling detection signal is output until the boiling state in the pot ends, and the longer the time obtained by the measurement, the longer the time is set to the heater power-off means. and a correction means for correcting the rising temperature to become higher, and the boiling detection means is configured to change the target temperature gradient so that the larger the amount of rice indicated by the rice cooking amount signal is, the smaller the target temperature gradient becomes. A rice cooker characterized by: 2. Claim 1, characterized in that the correction means is configured to measure the time from when the boiling detection signal is output until the temperature of the pot rises to a predetermined boiling end temperature. The rice cooker described in. 3. The boiling detection means is provided to measure the temperature gradient based on the amount of change in the temperature detection signal within a predetermined reference time, and the reference time becomes longer as the amount of cooked rice indicated by the rice cooking amount signal increases. The rice cooker according to claim 1, characterized in that the rice cooker is configured to change as follows. 4. The boiling detection means is provided to measure the temperature gradient by comparing the amount of change in the temperature indicated by the temperature detection signal within a certain period of time with a reference temperature, and the boiling detection means is configured to measure the temperature gradient by comparing the amount of change in the temperature indicated by the temperature detection signal within a certain period of time with a reference temperature, and the boiling detection means The rice cooker according to claim 1, wherein the rice cooker is configured to change the amount so that the amount becomes lower as the amount increases. 5. The boiling detection means is configured to enable the boiling detection function only when the temperature indicated by the temperature detection signal exceeds a predetermined lower limit temperature. The rice cooker described in. 6. Claim 1, characterized in that the rice cooking amount detection means is configured to detect the rice cooking amount according to the magnitude of the amount of change in temperature per unit time indicated by the temperature detection signal. The rice cooker mentioned.