JP7591395B2 - Rice cooker - Google Patents

Description

The present invention relates to a rice cooker that performs a warming process to keep rice warm.

Conventionally, rice cookers are configured to automatically switch to a rice-keeping process when the rice cooking process is completed. It is known that the longer the period of the keeping-warm process, the worse the taste of the rice becomes. However, it is difficult to objectively know until when the rice is equivalent to freshly cooked after the process has been switched to the keeping-warm process, as this depends on the user's subjective sense. For example, as in Reference 1, a device is known in which the user selects a taste assurance time, and the heating control of the keeping-warm process is changed according to the selected taste assurance time to maintain the taste of the rice. The applicant of the present application has also proposed a device that maintains the taste of rice by spraying steam onto the rice while it is being kept warm (Reference 2).

JP 2014-014546 A JP 2009-119297 A

If the user could objectively grasp the changes in the state of the rice while it was being kept warm, such as whether the rice tasted freshly cooked when eaten, whether it was close to being freshly cooked, or whether it could no longer be called freshly cooked, it would be easier to tell whether the rice was good or bad, and there would be less discrepancy between the actual taste of the rice and the user's subjective sensory perception of the taste of the rice. However, because the conventional technology described above preserves the taste of the rice during the keeping-warm process, the taste still differs from that of freshly cooked rice immediately after cooking.

Figure 15 is an explanatory diagram showing an example of the qualitative and quantitative viewpoints of freshly cooked rice. Here, the difference between freshly cooked rice and warmed or cold rice is whether the umami components dissolved from the rice grains during cooking become sticky water and adhere to the rice grains, whether the sticky water gives the rice a transparent luster and stickiness around the rice grains, and whether the rice is "hot" at about 100°C. However, the above-mentioned conventional technologies maintain the taste of rice during the warming process. For example, the technology of Reference 1 is mentioned in the context of warming and does not have the concept of freshly cooked rice, and the technology of Reference 2 simply supplies water because the sticky water containing the umami components that adhere to the rice grains specific to freshly cooked rice is different from the sprayed steam, and the taste is different from that of freshly cooked rice immediately after cooking.

There is also known technology that allows users to check the state of the rice after cooking has finished by displaying the time that has elapsed since the start of the keep-warm process, but most products display this elapsed time in one-hour increments, which is too long and makes it difficult for users to tell whether the rice is freshly cooked or not. There is also known technology that displays the elapsed time in shorter increments, but because users cannot tell how long the rice is freshly cooked, this ends up being a function that unnecessarily just changes the display of the elapsed time.

Therefore, the present invention aims to provide a rice cooker that allows you to monitor the condition of rice while it is being kept warm.

In order to achieve the above object, the rice cooker of the present invention comprises a pot for containing rice and water as the food to be cooked, heating means for heating the pot, control means for controlling the heating means, display means for displaying information related to cooking, and pot temperature detection means for detecting the temperature of the pot, and the control means controls the heating means to carry out a rice cooking process in which the pot is heated and the food to be cooked is cooked, and a warming process in which the rice cooked in the rice cooking process is kept warm in that order, and the warming process includes an initial warming stage in which the temperature of the rice is 90°C or higher within 30 minutes after the end of the rice cooking process, and a warming stage in which the temperature of the rice is 90°C or higher within 30 minutes after the end of the rice cooking process . the period being within 60 minutes from the start of the warming process, and including, after the initial warming period, a warming-down period in which the temperature of the rice is lowered, and a warming-stable period in which the rice lowered in the warming-down period is kept warm at a predetermined temperature, the control means lowers the temperature while controlling the heating means to be turned on and off based on the temperature detected by the pot temperature detection means during the warming-down period, and the display means displays, in a plurality of displays, the warming time, which is the elapsed time from the start of the warming process, and the state of change in the warming process to the initial warming process, the warming-down period, and the warming-stable period .

The rice cooker of the present invention allows you to monitor the state of the rice during warming. It also prevents condensation on the inside of the pot and prevents the soup from dripping onto the rice, and keeps the rice in a freshly cooked state even during the warming down period, maintaining the taste of the rice equivalent to that of freshly cooked rice.

1 is a vertical cross-sectional view of a rice cooker according to a first embodiment of the present invention. FIG. FIG. 13 is a block diagram showing the electrical configuration of the first embodiment. FIG. 13 is a graph showing the changes in temperature detected by the pot sensor, the lid temperature sensor, and the power of the heating means. 13 is a graph showing the changes in temperature detected by the pot sensor, the lid temperature sensor, and the temperature of the rice in the pot during the keep-warm process. 6A is a diagram showing the temperature measurement locations in FIG. 5, and FIG. 6B is a graph showing an example of the changes in temperature detected by the pot sensor, the lid temperature sensor, and the temperature of the rice in the pot. 1 is a diagram showing the transition of the display on the LCD according to the first embodiment; FIG. 11 is a graph showing the correlation between the temperature at which rice is kept warm and the deterioration of its taste. FIG. 11 is a top view of an operation panel of a rice cooker in a second embodiment of the present invention. FIG. 13 shows the LCD display when the temperature of the rice approaches the keep-warm set temperature. FIG. 13 shows the LCD display after the power supply to the rice cooker is stopped and then re-supplied. (A) A figure showing the LCD display of a rice cooker in the third embodiment of the present invention during the keep-warm process after the power supply is stopped and then restarted during the cooking process; (B) The same as above, a figure showing the LCD display after the power supply is stopped and then restarted during the keep-warm process; (C) The same as above, a figure showing the LCD display when the keep-warm process is started manually without performing the cooking process. FIG. 13 is a diagram showing the transition of the display on the LCD of the rice cooker according to the fourth embodiment of the present invention. FIG. 13 is a block diagram showing the electrical configuration of a rice cooker according to a fifth embodiment of the present invention. FIG. 1 is an explanatory diagram showing an example of a qualitative perspective and a quantitative perspective of freshly cooked rice.

Each embodiment of the rice cooker of the present invention will be described below with reference to the attached drawings. Note that common parts are designated by common reference numerals throughout these drawings.

Figures 1 to 8 show a first embodiment of the rice cooker of the present invention. The overall structure of the rice cooker will be explained based on Figure 1. 1 is a rice cooker, which is generally rectangular when viewed from above with the front and back, left and right sides facing each other, and is generally made up of a main body 2 of the rice cooker 1 with an open top, and a lid 3 that can be opened and closed to cover the top opening of the main body 2. The main body 2 has a pot housing 4 that is open at the top, and when the lid 3 is opened, a bottomed pot 5 that serves as a container for holding water and rice to be cooked is detachably housed in the pot housing 4. The pot housing 4 is composed of a combination of a bowl-shaped resin inner frame 6 and a metal inner frame ring 7, and is generally formed into a bottomed cylindrical shape.

The pot 5 has a main material 8 made of aluminum, which has good thermal conductivity, and a heating element 9 made of a magnetic metal plate such as ferritic stainless steel, which is joined to the outer surface of the main material 8 from the lower side to the bottom. The outer surface of the inner frame ring 7 facing the outer surface of the pot 5 is equipped with a body heater 11 that uses a cord heater as an example of a heating means. In addition, the outer surface of the inner frame 6 facing the lower side to the bottom of the pot 5 is equipped with a heating coil 12 as a heating means for electromagnetic induction heating the heating element 9 of the pot 5.

A pot sensor 14, which serves as a pot temperature detection means, is disposed in the center of the bottom of the inner frame 6 so as to make elastic contact with the outer bottom of the pot 5. In this embodiment, the pot sensor 14 is configured to detect the temperature of the pot 5 and mainly control the heating temperature of the bottom of the pot 5 by the heating coil 12.

A lid-opening button 15 is provided on the front upper surface of the lid 3 in an exposed state. When the lid-opening button 15 is pressed, the engagement between the main body 2 and the lid 3 is released, and the lid 3 is automatically opened around a hinge shaft 16 by a hinge spring (not shown) provided at the upper rear of the main body 2. A rotation sensor (not shown) is provided on the hinge shaft 16, which is configured to send a detection signal to a control IC 42 of the heating control means 40 (described later) when the lid 3 is opened. A steam vent unit 17 is detachably attached to the rear upper surface of the lid 3, which exhausts steam generated from the food being cooked in the pot 5 to the outside of the rice cooker 1.

In addition to the lid opening button 15 and steam vent unit 17, the top surface of the lid body 3 is provided with an operation panel 20, which serves as the display and operation unit of the rice cooker 1. The operation panel 20 is equipped with a display section 18 that displays various information related to cooking, and an operation section 19 for starting rice cooking and selecting the time and cooking course, and below these is a control PC (Printed Circuit) board 47 equipped with a display and operation control means 46, which is the control means of the operation panel 20. The control PC board 47 has a patterned conductive circuit section, and by mounting a control IC related to operation and display on this control PC board 47, the display and operation control means 46 linked to the heating control means 40 described below is formed.

An inner lid assembly 21 is disposed under the lid 3 as a lower member of the lid 3. The inner lid assembly 21 is made of a metal material having a disk shape with approximately the same diameter as the upper opening of the pot 5, and includes an inner lid 22 that covers the upper opening of the pot 5, a lid packing 23 as an elastic member provided around the entire outer circumference of the inner lid 22 to seal between the inner lid 22 and the pot 5, and a pressure adjusting section 24 that adjusts the internal pressure of the pot 5. The annular lid packing 23 abuts against the upper surface of the opening of the pot 5 when the lid 3 is closed as shown in FIG. 1, blocking the gap between the pot 5 and the inner lid 22 and sealing off the steam generated from the pot 5.

Inside the lid body 3, a lid heater 33 as a lid heating means for heating the inner lid 22 and a thermistor-type lid temperature sensor 34 for controlling the temperature of the inner lid 22 by the lid heater 33 are provided. In addition, a steam exhaust path 25 that connects the steam port unit 17 and the pressure adjustment section 24 is formed as a passage for releasing steam generated in the pot 5 to the outside. The pressure adjustment section 24 is provided with a pressure adjustment valve 26 that opens and closes the steam exhaust path 25 between the inside of the pot 5 and the steam port unit 17. The pressure adjustment valve 26 is ball-shaped and works in conjunction with a solenoid 27 provided inside the lid body 3. The solenoid 27 rotates the pressure adjustment valve 26 so that the steam exhaust path 25 is opened when steam in the pot 5 is released to the outside, and the steam exhaust path 25 is closed when the inside of the pot 5 is pressurized or depressurized. During pressurization, the food being cooked in the pot 5 is heated by passing high-frequency current through the heating coil 12, and when the internal pressure of the pot 5 reaches a predetermined value, the pressure inside the pot 5 is maintained at or above atmospheric pressure by opening the steam exhaust path 25 against the weight of the pressure adjusting valve 26.

28 is a pressure reducing means for lowering the pressure inside the pot 5 below normal atmospheric pressure when the lid 3 is closed on the main body 2. The pressure reducing means 28 accommodates the pot 5 in the pot container 4, closes the lid 3, and then energizes the solenoid 27 to reduce the internal pressure of the sealed pot 5 when the pressure regulating valve 26 blocks the steam exhaust path 25. When the pressure inside the pot 5 drops below atmospheric pressure by a certain value, the operation of the pressure reducing pump 29, which is the operating source of the pressure reducing means 28, is stopped, and the inside of the pot 5 is kept in a reduced pressure state. Furthermore, when the inside of the pot 5 is to be returned from the reduced pressure state to the same pressure as the outside air, the operation of the pressure reducing pump 29 is stopped, and a path (not shown) that connects the pressure reducing pump 29 to the inside of the pot 5 is opened. In other words, the pressure reducing means 28 also serves as a pressure return means for returning the inside of the pot 5 from the reduced pressure state to the same pressure as the outside air.

In addition, a unitized heating board assembly 41 including a heating control means 40 is disposed inside the main body 2. The heating control means 40 is configured to include a microcomputer (microcomputer) equipped with a control IC 42 and a memory means 51 (see FIG. 2) in combination with the display/operation control means 46 to electrically control each part of the rice cooker 1. Here, the heating control means 40 receives temperature detection signals from the pot sensor 14 and the lid temperature sensor 34 and an operation signal from the operation unit 19 to control the body heater 11 and heating coil 12 that heat the pot 5 during cooking and keeping warm, and the lid heater 22 that heats the lid body 3, and also controls the operation of the solenoid 27 and the pressure reduction pump 29. In particular, the heating control means 40 mainly controls the heating coil 12 based on the detected temperature of the pot sensor 14 to manage the temperature of the bottom of the pot 5, and mainly controls the lid heater 22 based on the detected temperature of the lid temperature sensor 34 to manage the temperature of the inner lid 24 facing the food to be cooked.

Next, the control system of the heating control means 40 and the display/operation control means 46 will be described with reference to FIG. 2. In the figure, the heating control means 40 equipped in the main body 2 includes a control IC 42 and a memory means 51 that constitute a microcomputer, and receives temperature detection signals from the pot sensor 14 and the lid temperature sensor 34 and a control signal from the display/operation control means 46 to control the body heater 11 and the heating coil 12 that heat the pot 5 during cooking and keeping warm, and the lid heater 33 that heats the inner lid 24, respectively, and also controls the operation of the solenoid 27 that operates the pressure regulating valve 26 and the pressure reducing means 28. In particular, the heating control means 40 mainly controls the heating coil 12 based on the detected temperature of the pot sensor 14 to manage the temperature of the bottom of the pot 5, and mainly controls the lid heater 22 based on the detected temperature of the lid sensor 34 to manage the temperature of the inner lid 24. These heating coils 12, lid heater 22, and the aforementioned body heater 11 correspond to the heating means 52 that heats the food to be cooked in the pot 5.

The heating control means 40 has a rice cooking control means 53, a heat keeping control means 54, and a rice reservation cooking means 55 in the control IC 42 as functions in the control sequence of the program read from the storage means 51. The rice cooking control means 53, upon receiving an instruction to start cooking rice from the operation unit 19, for example, the rice cooking key, sequentially executes each process of a soaking process to promote the absorption of water by the rice put into the pot 5, a boiling heating process that combines a temperature increase process to raise the temperature of the rice to boiling in a short time and a boiling continuation process to keep the rice boiling, and a steaming process to maintain the rice at a high temperature that does not burn, and cooks the rice in the pot 5 at the desired pressure. The heat keeping control means 54 controls the rice in the pot 5 to be kept at a predetermined heat keeping temperature. The reservation cooking means 55 has a timer function, and when the cooking completion time (cooking completion time) is set and the timer operation is started, the cooking control means 53 automatically starts cooking rice a specified time before the cooking completion time so that the rice is cooked at the set cooking completion time, and the keep-warm control means 54 starts keeping the rice warm at the cooking completion time.

On the other hand, the display/operation control means 46 includes a control IC 48, a storage means 57, a timer means (not shown), and the like that constitute a microcomputer, and controls the display operation of the display unit 18 upon receiving an operation signal from the operation unit 19 or a control signal from the heating control means 40, and also transmits a control signal to the heating control means 40. As a function of the control sequence of the program stored in the storage means 57, the display/operation control means 46 includes an operation unit control means 58 that generates various control signals based on an operation signal from the operation unit 19, a display operation control means 59 that controls the display operation of the display unit 18, and a condition setting means 60 that cooperates with the operation unit control means 58 and the display operation control means 59 to select and set conditions that can be selected by the operation unit 43, for example, to select and set a desired cooking course or rice cooking course from a plurality of cooking courses or rice cooking courses.

3 is a top view of the main part of the rice cooker 1 of this embodiment. An operation panel 20 is arranged on the top surface of the lid body 3, and "Koshihikari Minami-Uonuma" and "White rice" are selected and displayed on the LCD 76 of the display unit 18 of the operation panel 20, which will be described later, and indicates that the state is after 10 minutes of keeping warm after cooking. Referring to this FIG. 3, the operation unit 19 is composed of a reservation key 63 arranged side by side on the right side of the operation panel 20, a forward key 64, a back key 65, a cooking key 66, a keep warm key 67, and an off key 68, as well as a brand key 69 arranged side by side on the lower part of the operation panel 20, a cooking method key 70, a sweetness key 71, a menu key 72, and a touch sensor 73 arranged on the top surface of the LCD 76. Here, each of the keys 63 to 72 cannot be operated by the user's touch operation, but functions as a push-type operation means such as a tactile switch that can be operated by pressing, and the touch sensor 73 is connected to the control PC board 47, and functions as a non-pushing type operation means such as a touch key that can be operated by the user's touch operation.

The off key 68 is operated to stop cooking or keeping the rice warm. When the off key 68 is pressed, the operation unit control means 58 accepts an operation signal from the off key 68 and sends it to the heating control means 40, and the rice cooking control means 53 stops heating the food inside the main body 1 and switches the cooking state to the off state.

The rice cooking key 66 is operated to start cooking rice. When the rice cooking key 66 is pressed, the operation control means 58 accepts an operation signal from the rice cooking key 67 and sends it to the heating control means 40, and the rice cooking control means 53 controls the start of cooking the food inside the main body 1.

The keep warm key 67 is operated when keeping food warm. When the keep warm key 67 is pressed, the operation control means 58 accepts an operation signal from the keep warm key 67 and sends it to the heating control means 40, and the keep warm control means 54 controls the start of keeping warm and reheating the food inside the main body 1.

The reservation key 63 is operated when performing scheduled rice cooking. After pressing the reservation key 63 and setting the reservation time and cooking course, pressing the rice cooking key 66 causes the operation unit control means 58 to accept an operation signal from the rice cooking key 62 and send it to the heating control means 40, and the scheduled rice cooking means 55 controls the rice cooking control means 53 to start cooking so that the food inside the main body 1 is cooked at the previously set reservation time, and also controls the keep-warm control means 54 to start keeping the food warm.

The forward key 64 and back key 65 are used to set the rice brand, cooking method, sweetness, and menu selection screen described below, as well as to adjust the reservation time, current time, and cooking time.

The brand key 69 is operated when setting the brand of rice, for example, "Koshihikari from Minami-Uonuma." When the brand key 69 is pressed, the operation unit control means 58 accepts an operation signal from the brand key 69 and transitions to a rice brand selection screen. The cooking method key 70 is operated when setting the cooking method of rice, for example, the hardness and stickiness of the cooked rice. When the cooking method key 70 is pressed, the operation unit control means 58 accepts an operation signal from the cooking method key 70 and transitions to a rice cooking method selection screen. The sweetness key 71 is operated when setting the sweetness of the cooked rice. When the sweetness key 71 is pressed, the operation unit control means 58 accepts an operation signal from the sweetness key 71 and transitions to a rice sweetness selection screen. The menu key 72 is operated when setting the rice menu, such as "white rice" or "seasoned rice." When the menu key 72 is pressed, the operation unit control means 58 accepts the operation signal from the menu key 72 and transitions to a rice menu selection screen. In these selection screens, the forward key 64, the back key 65, and the touch sensor 73 are used to select and set the rice brand, rice cooking method, rice sweetness, and rice menu, respectively.

The touch sensor 73 is configured such that a plurality of components are arranged as touch keys, each of which is formed by connecting a transparent electrode section made of a conductive polymer to a contact section connected to the control PC board 47 with pattern wiring. When a fingertip is touched with any of a plurality of display elements 81 displayed on the LCD 76 below the touch sensor 73, the touch key arranged above that display element 81 and corresponding to that display element is touched and the display element 81 is selected.

The display unit 18 is composed of an LCD 76 which displays the current time, the selected brand of rice, the rice menu and the time since cooking is complete, and a "Reservation" LED 77, a "Cooking" LED 78 and a "Keep Warm" LED 79 which are arranged in a line on the upper part of the operation panel 20 and display the rice cooker's progress. Explaining the display elements 81 arranged on the LCD 76 with reference to FIG. 3, there are arranged a clock display element 81-1 that displays the current time, a cooked rice reservation display element 81-2 that displays the reservation time for completion of rice cooking when reservation cooking is set, a "freshly cooked" display element 81-3 that displays the state of the rice during the warming process as described below, arrow display elements 81-4, 81-5, 81-6, a "keep warm" display element 81-7, a keep warm time display element 81-8, a rice brand display element 81-9 that displays the selected brand of rice, a "white rice" display element 81-10 that displays the selected menu in white letters with a black background, a "cooked rice" display element 81-11, a "rice porridge" display element 81-12, a "brown rice" display element 81-13, a "white rice quick cooking" display element 81-14, a "risotto" display element 81-15, and a "paella" display element 81-16.

Next, the operation of the rice cooker 1 configured as described above in the rice cooking process will be described with reference to Fig. 4. Fig. 4 is a graph showing the changes in the temperature t1 detected by the pot sensor 14, the temperature _t2 detected by the lid temperature sensor 34, and the output W of the heating means 52 in the rice cooking process and the warming process of the rice cooker ₁ of this embodiment.

First, the operation of this embodiment during rice cooking will be described. Rice and water are placed in the pot 5 as the food to be cooked, and then the pot is placed in the pot housing 4 of the main body 2, and the lid 3 is closed. Around the same time, when the power plug of the rice cooker 1 is inserted into the outlet and power is applied, the rice cooker 1 goes into the initial off (standby) state in which no cooking or warming is taking place, and the display and operation control means 46, in cooperation with the display operation control means 59, displays the current rice cooking course setting on the display unit 18. Here, each time the brand key 69, cooking method key 70, sweetness key 71, menu key 72, forward key 64, back key 65, or touch sensor 73 of the operation unit 19 is operated, the operation signal is received by the operation unit control means 58, and the setting of the rice cooking course is changed by the condition setting means 60. The changed setting is displayed on the display unit 18 by the display operation control means 59 each time, and the user can visually confirm this.

When the operation unit 19, for example the rice cooking key 66, is operated, the operation signal is received by the operation unit control means 58, the display operation control means 59 controls the "rice cooking" LED 78 to light up, and the condition setting means 60 stores the rice cooking course displayed on the display unit 18 in the storage means 57 as the currently set rice cooking course, and sends information on the heating pattern corresponding to the set rice cooking course to the heating control means 40. In response to this, the heating control means 40 performs each of the rice cooking operations for the food to be cooked in the pot 5, such as the soaking process, the heating process, the continued boiling process, and the steaming process, using the rice cooking control means 53 built into the control IC 42, in accordance with the heating pattern of the set rice cooking course.

When the information sent from the display and operation control means 46 is received, the rice cooking control means 53 controls the energization and deenergization of the heating coil 12 and the body heater 11 based on the temperature detection of the bottom of the pot 5 by the pot sensor 14, thereby heating the bottom and sides of the pot 5, and raising the water temperature in the pot 5 to a predetermined temperature, for example 45 to 60°C, to perform a soaking process that promotes water absorption by the rice. The soaking process is configured to maintain the water temperature in the pot 5 at a predetermined temperature for a predetermined time, for example 3 minutes.

During the soaking process, the rice cooking control means 53 controls the operation of the solenoid 27 and the pressure reducing means 28 so that the pressure inside the pot 5 is reduced below atmospheric pressure. Specifically, when the soaking process starts, the rice cooking control means 53 switches the solenoid 27 from a non-energized state to an energized state, and closes the steam exhaust path 25 with the pressure regulating valve 26. In this state, the path of the pressure reducing means 28 is opened and the pressure reducing pump 29 is operated continuously to perform a vacuum extraction in which the air inside the sealed pot 5 is removed by the pressure reducing pump 29. After that, when the pressure inside the pot 5 drops to a certain value below atmospheric pressure, the operation of the pressure reducing pump 29 is stopped. In this way, the inside of the pot 5 is kept in a reduced pressure state for a predetermined time, which is the entire period of the soaking process. Therefore, it is possible for the rice inside the pot 5 to sufficiently absorb water during the soaking process.

After that, when the soaking process for a predetermined time is completed and the process moves to the next heating process of the boiling heating process, the rice cooking control means 53 controls the heating coil 12 and the body heater 11 to be continuously energized until the boiling of the food is detected, thereby heating the food in the pot 5 more strongly than in the soaking process and raising the temperature of the food to boiling in a short time. Here, the rice cooking control means 53 controls to close the path of the pressure reducing means 28 in order to maintain the inside of the pot 5 in a reduced pressure state lower than atmospheric pressure after the soaking process. Therefore, even after the transition from the soaking process to the heating process, the pressure inside the pot 5 gradually increases due to heating to the pot 5 and slow leakage, but the reduced pressure state can be maintained for a while without operating the pressure reducing pump 29. In this way, the food inside the pot 5 is kept in a reduced pressure state even in the heating process after the soaking process, so that the water boils at a temperature of 100°C or less during the heating process. Therefore, by boiling the food under reduced pressure at 60℃ to 100℃, the gelatinization temperature of rice, the rice is stirred up by the bubbles produced by the boiling process, eliminating uneven heating, and by placing the food under reduced pressure, the rice can absorb water all the way to its core in a short period of time.

Next, the rice cooking control means 53 takes in the temperature detection signal from the pot sensor 14, and when the detected temperature at the bottom of the pot 5 reaches the predetermined temperature of 100°C, it determines that the food inside the pot 5 has boiled under reduced pressure, closes the path of the pressure reducing means 28, does not operate the pressure reducing pump 29, and temporarily de-energizes the solenoid 27 to retract the pressure regulating valve 26. This causes the steam exhaust path 25 to be in an open state where the inside and outside of the pot 5 are not sealed but are connected, and the inside of the pot 5 immediately returns to normal pressure, the same as the outside air. After that, the rice cooking control means 53 switches the solenoid 27 to a conductive state in a short time and seals the inside of the pot 5 again, and since the food inside the pot 5 continues to be strongly heated, the food inside the pot 5 is pressurized until it reaches atmospheric pressure or higher, for example 1.2 atm, and the food can be boiled under this pressurized state. In this way, when the rice cooking control means 53 determines that the food inside the pot 5 has boiled under reduced pressure during the heating process, it instantly switches the inside of the pot 5 from a reduced pressure state to a pressurized state higher than atmospheric pressure, and controls the operation of the solenoid 27 and, in turn, the pressure adjustment valve 26 constituting the pressure adjustment section 24 to temporarily open the steam exhaust path 25 in order to apply a pressure shock to the food. This ensures a balance between the hardness and stickiness of the rice, and allows the rice to be gelatinized all the way to the core in one go by boiling the food inside the pot 5 from a reduced pressure state to a pressurized state of 105°C (at 1.2 atmospheres).

Then, when the rice cooking control means 53 detects that the temperature of the bottom of the pot 5 has reached a predetermined temperature or higher, for example 90°C, from the temperature detection signal from the pot sensor 14, and also detects that the temperature of the inner lid 22 has reached a predetermined temperature or higher, for example 90°C, from the temperature detection signal from the lid temperature sensor 34, it starts boiling detection to detect boiling of the food under pressure. Specifically, it continues to control the continuous current flow to the heating coil 12 and the body heater 11 to strongly heat the food inside the pot 5, while calculating the slope of the detected temperature, which is how much the detected temperature of the lid temperature sensor 34 rises in a predetermined time. Then, when the slope of the detected temperature of the lid temperature sensor 34 reaches a certain value or less and stabilizes, the rice cooking control means 53 determines that the food inside the pot 5 has reached boiling under pressure, and moves to the next boiling continuation process.

When the process moves to the continuing boiling step, the rice cooking control means 53 controls the lid heater 33 to start heating the lid. The amount of heat from the lid heater 33 is managed by the temperature detected by the lid temperature sensor 34 so that the temperature of the inner lid 22 becomes a predetermined temperature, for example 100°C. When the process moves to the continuing boiling step, the rice cooking control means 53 periodically controls the solenoid 27 to be turned on and off, and periodically opens and closes the steam exhaust path 25 with the pressure regulating valve 26, in order to repeatedly change the pressure inside the pot 5 between normal pressure and a temperature higher than atmospheric pressure.

The rice cooking control means 53 detects that the water inside the pot 5 has run out during the continuing boiling process and that a predetermined temperature rise has occurred based on the temperature detection signal from the pot sensor 14 at the bottom of the pot 5, and detects that the food is cooked based on the temperature detected by the pot sensor 14. Here, when the temperature detected by the pot sensor 14 reaches a predetermined dry-up temperature, it detects that the food inside the pot 5 is cooked, the continuing boiling process ends, and the process moves from the boiling heating process to the next steaming process.

During the steaming process, the rice cooking control means 53 controls the temperature by turning on and off the lid heater 22 based on the temperature detected by the lid temperature sensor 34 to prevent condensation on the inner lid 22, and controls the temperature at the bottom of the pot 5 by turning on and off the heating coil 12 and the body heater 11 so that the rice inside the pot 5 is kept at a high temperature so that it does not burn. The steaming process continues for a specified time, for example 12 minutes, and when the steaming process is completed, the rice moves to a warming process by the warming control means 54.

Next, the operation of the rice cooker 1 in the warming step will be described with reference to Fig. 5 to Fig. 7. Fig. 5 is a graph showing the transition of the temperature of the rice in the pot 5, the temperature of the inner surface of the pot 5, and the temperature of the inner surface of the inner lid 22 in the warming step of the rice cooker 1 of this embodiment. The temperature was measured at (1) and (2) in Fig. 6(A) for the temperature of the rice in the pot 5, (3) and (4) in Fig. 6(A) for the temperature of the inner surface of the pot 5, and (5) and (6) in Fig. 6(A) for the temperature of the inner surface of the inner lid 22 facing the pot. The average value of the values measured in (1) and (2) is temperature _tR , the average value of the values measured in (3) and (4) is temperature _t3 , and the average value of the values measured in (5) and (6) is temperature _t4 , and the transition of the temperatures _tR , _t3, and _t4 is shown in the graph.

Even when the steaming process is over and cooking is complete, the user is not necessarily near the rice cooker. For example, even if the user receives a notification from the rice cooker 1, it is rare for the user to eat freshly cooked rice immediately after the rice cooker has switched to the keep-warm process. Therefore, the time that has elapsed since the rice cooker switched to the keep-warm process until the user first opens the lid 3 and eats the rice is not fixed. Although there are individual differences, users tend to expect the sensory taste of freshly cooked rice when they first open the lid 3 after the rice cooker has switched to the keep-warm process, even after a certain amount of time, for example 30 minutes, has elapsed. However, as shown in FIG. 15 above, as the temperature of the rice drops from 100°C, which is the temperature of the rice immediately after cooking when the rice cooker has switched to the keep-warm process, to the keep-warm temperature that keeps the temperature of the rice at 67°C to 78°C, preferably 70°C to 76°C, the taste of the rice decreases, so depending on the amount of time that has passed or the degree of the drop in the temperature of the rice, the user may not be able to obtain the taste of freshly cooked rice that he or she expects.

Specifically, when the cooking process ends and the rice is kept warm, the amount of water evaporated from the rice increases with time and the temperature of the rice drops, and the weight of the rice decreases compared to the rice immediately after cooking, resulting in a deterioration in taste. Also, when the temperature of the rice drops, the amount of water evaporating from the steam outlet unit 17 to the outside of the rice cooker 1 via the steam exhaust path 25 gradually decreases, while water adheres to the inside of the pot 5 and the inner lid 22, increasing the amount of condensation. As a result, the water content of the rice near the upper wall of the pot 5, that is, above the pot skin, gradually increases, and the rice becomes softer and less firm compared to the rice immediately after cooking. Then, the paste-like substance on the surface of the rice grains, which is the flavor component of rice, absorbs the remaining water that cannot evaporate, loses fluidity as the temperature drops, and the rice grains firmly adhere to each other, causing the rice grains to become ball-shaped and the taste to deteriorate. Furthermore, if there is a lot of condensation on the inner walls of the pot 5 or the inside of the inner lid 22, this condensation will drip onto the rice, making it watery and further degrading the taste, resulting in the rice no longer having the flavor of freshly cooked rice.

On the other hand, it is also possible to open the lid 3 after the cooking process is completed to loosen the rice in the pot 5 and allow excess moisture to diffuse and be released outside the rice cooker 1. However, while this certainly helps prevent the deterioration in taste caused by excess moisture as described above, if the timing of this diffusion and release is delayed, the rice will feel like it is freshly cooked, but in reality, the taste of the rice will have deteriorated from that of freshly cooked rice.

The deterioration in taste during the warming process after the end of the cooking process varies depending on the product characteristics of the rice cooker 1, the amount of rice cooked, the ambient temperature, and the quality of the rice, but as a guideline for a significant deterioration in taste, for example, it is generally within 30 minutes after the start of the warming process, and the temperature guidelines are that the temperature of the cooked rice is 85°C or less, the temperature of the space above the rice in the pot 5 is 75°C or less, which is relatively lower than the temperature of the rice, and the temperature of the inside of the inner lid 22 is 73°C or less, which is relatively lower than the temperature of the rice in the pot 5. These guidelines are to be appropriately considered depending on the product characteristics of the rice cooker 1, the amount of rice cooked, the ambient temperature, and the quality of the rice.

Therefore, in this embodiment, a separate control is provided for the initial stage of the warming process as the "freshly cooked" period after the rice cooking process is completed. Specifically, when time is used as a parameter, the initial stage of warming _T1 is a period within 30 minutes, preferably within 10 minutes, from the start of the warming process, while when temperature is used as a parameter, the initial stage of warming _T1 is a period during which the temperature of the rice is 90°C or higher, preferably 95°C or higher, and the initial stage of warming _T1 and the initial stage of warming _T2 are set as the "freshly cooked" period. _The temperature of the inner surface of the pot 5 and the temperature of the inner surface of the inner lid 22 are controlled to be higher than the temperature of the rice in the pot 5 on average to prevent condensation.

Explaining with reference to Figure 5, the warming process of this embodiment is composed of an initial warming period T1 which is a period within 30 minutes, preferably within 10 minutes, from the start of the warming process or a period during which the temperature of the rice is 90°C or higher, preferably 95°C or higher _{; a warming decrease period T2 which} follows the initial warming period _T1 and is within 60 minutes from the start of the warming process, during which the temperature of the rice is gradually decreased; and a stable warming period _T3 which is more than 60 minutes from the start of the warming process, during which the temperature of the rice is controlled to be kept at the warming set temperature, for example 73°C ±3°C.

In the rice cooker 1, the freshness of the rice in the pot 5 decreases as the warming time progresses. The deterioration in taste during the warming process after the end of the cooking process varies depending on the product characteristics of the rice cooker 1, the amount of rice cooked, the environmental temperature, and the quality of the rice. However, a questionnaire survey on the freshness of freshly cooked rice conducted by the applicant's product showed that most people feel that rice is "freshly cooked" within 10 minutes after the cooking process ends and the warming process begins, and most people can accept that rice is "freshly cooked" within 30 minutes after the warming process begins, and almost no users can accept rice that has been "freshly cooked" for more than 60 minutes. In this embodiment, the period of the warming initial period _T1 and the warming decreasing period _T2 is configured as the "freshly cooked" period based on this result.

The freshness of this cooked rice decreases at different speeds depending on the product characteristics of the rice cooker 1, the amount of rice cooked, the ambient temperature, the variety of rice, etc., so the present invention is not limited to these descriptions, and the values in this embodiment are merely examples. It is preferable that the freshness of freshly cooked rice is determined according to whether the amount of rice cooked in the rice cooker 1 is large or small, whether the ambient temperature around the rice cooker 1 is high or low, the hardness and stickiness of the variety of rice, and according to the product-specific characteristics of the rice cooker 1, and it is also preferable that the elapsed time of keeping warm and the temperature of the rice are determined for this freshness of freshly cooked rice state.

In this embodiment, when the warming process is started, the warming control means 54 controls the operation of the solenoid 27 and the pressure reducing means 28 so that the pressure inside the pot 5 is reduced to a state lower than atmospheric pressure. Fig. 8 shows the correlation between the warming temperature of rice and the deterioration of its taste. It is well known that if the warming temperature is high, browning due to the Maillard reaction, so-called yellowing, occurs early, the rice becomes dry and hard, and a warming odor occurs early due to the Maillard reaction and oxidation of fatty acids. The Maillard reaction (or aminocarbonyl reaction) is a reaction in which reducing sugars contained in food and rice react with amino compounds of amino acids, peptides and proteins by heating to produce melanoidin, a brown substance, and it is believed that melanoidin is the true identity of the browning fox color mentioned above. The temperature at which the Maillard reaction is most active varies depending on the food, but is said to be around 155°C, and browning due to the Maillard reaction becomes intense after about 4 hours at around 100°C and about 12 hours at 67°C to 78°C. Therefore, during the initial warming period _T1 in the rice cooker 1 of this embodiment, browning that is actually harmful to the rice in the pot 5 does not progress, but if the amount of rice cooked in the rice cooker 1 is large or the temperature in the environment around the rice cooker 1 is high, the temperature of the rice in the pot 5 after freshly cooked heating will decrease slowly, and if the rice cooker 1 keeps the rice warm for a long period of time during the subsequent warming stable period _T3 , for example, for more than 12 hours or more than 24 hours, browning due to the Maillard reaction may occur early.

Therefore, in the rice cooker 1 of this embodiment, in order to suppress deterioration of the rice in the pot 5 due to keeping it warm, the inside of the pot 5 is deaerated during the keeping warm process to suppress early browning due to the Maillard reaction described above after heating for freshly cooked rice, and deterioration of the rice in the pot 5 during the subsequent keeping warm period _T2 and stable warming period _T3 is suppressed compared to keeping the rice at a high temperature to maintain the freshly cooked state immediately after the start of the keeping warm process. Note that this deaeration is performed when the lid 3 is closed during each of the periods of initial keeping warm _T1 , keeping warm decreasing period _T2 , and stable warming period _T3 , including during heating for freshly cooked rice, but is not performed when the lid 3 is open.

To explain the operation during the initial warming stage _T1 , when the steaming process ends and the process moves to the warming process, the warming control means 54 calculates the temperature _tR of the rice in the pot 5 from the temperature detected by the pot sensor 14. The warming control means 54 then controls the temperature of the pot 5 by controlling the energization of the heating coil 12 and the body heater 11 according to the temperature detected by the pot sensor 14 so that the temperature _tR of the rice is maintained at 90°C or higher, and preferably 95°C or higher. The warming control means 54 also controls the temperature of the pot 5 by controlling the energization of the heating coil 12 and the body heater 11 according to the temperature detected by the pot sensor 14 so that the temperature _t3 of the inner side surface of the pot 5 is higher on average than the temperature of the rice _tR , and controls the temperature by controlling the energization of the lid heater 22 according to the temperature detected by the lid temperature sensor 34 so that the temperature _t4 of the pot-facing surface of the inner lid 22 is higher on average than the temperature _tR of the rice in the pot 5. As a result, it is possible to prevent dew formation on the inner side surface of the pot 5 and the pot-facing surface of the inner lid 22, and prevent the sauce from dripping onto the rice, so that the rice can be kept in a freshly cooked state and have a taste equivalent to that of freshly cooked rice.

As shown in FIG. 6(B), the heat retention control means 54 controls the temperature of the pot 5 by controlling the energization of the heating coil ₁₂ and the body heater 11 based on the temperature detected by the pot sensor 14 so that the temperature _t3 of the inner side surface of the pot 5 alternates between temperatures _tH1 , _tL1 , which are higher than the temperature of the rice, and the temperature of the inner lid 22 by controlling the energization of the lid heater 22 based on the temperature detected by the lid temperature sensor 34 so that the temperature _t4 of the pot-facing surface of the inner lid 22 alternates between temperatures _tH2 , tL2, which are higher than the temperature of the rice, and the temperature _tR , _tL2 , which is lower than the temperature of the rice. In these cases, when the temperature is lower than the rice temperature _tR , condensation occurs on the inner side surface of pot 5 and the pot-facing surface of inner lid 22, and when the temperature is higher than the rice temperature _tR , the condensed moisture evaporates, preventing the rice from becoming overhydrated due to excess moisture condensation and preventing the rice from drying out due to excess moisture evaporation, thereby maintaining the freshness of the rice as if it were just cooked. Here, these temperatures _tH1 , _tL1 , _tH2 , _tL2 are not specific temperatures, but are preferably relative temperatures that are Δt degrees higher or lower than the rice temperature _tR . In this case, it is preferable that temperatures _tH1 and _tL1 are set to approximately the same values, for example, +3°C and -3°C relative to the rice temperature _tR , to suppress condensation while suppressing the effect on the rice temperature _tR which is heated and controlled by the heating coil 12 and body heater 11, and temperatures _tH2 and _tL2 are set to, for example, +7°C and -3°C relative to the rice temperature _tR , to prevent condensation as much as possible, so that the time during which the temperature _t4 of the pot-facing surface of the inner lid 22 is higher than the rice temperature _tR is longer than the time during which it is lower than the rice temperature tR.

As shown in FIG. 6(B), it is preferable for the heat retention control means 54 to control the temperature of pot 5 so that during period _T11 , temperature _t3 is higher than the temperature _tR of the rice, while controlling the temperature of the inner lid 22 so that temperature _t4 is lower than the temperature _tR of the rice, and to control the temperature of pot 5 so that during period _T12 , temperature _t3 is lower than the temperature _tR of the rice, while controlling the temperature of the inner lid 22 so that temperature _t4 is higher than the temperature _tR of the rice, so that periods _T11 and _T12 are repeated alternately. As illustrated by the arrow marks shown below the graph, by configuring the inner side surface of pot 5 and the surface of inner lid 22 facing the pot to alternately condense and dry out, the decrease in freshness of the rice in pot 5 can be more effectively suppressed.

When the keep-warm process begins, the keep-warm control means 54 switches the solenoid 27 from a non-energized state to an energized state, and closes the steam exhaust path 25 with the pressure regulating valve 26. In this state, it opens the path of the pressure reducing means 28 and operates the pressure reducing pump 29 continuously, performing a vacuum by removing the air from inside the sealed pot 5 with the pressure reducing pump 29. Thereafter, when the pressure inside the pot 5 drops to a certain value below atmospheric pressure, the operation of the pressure reducing pump 29 is stopped. In this way, this series of operations is performed throughout the entire keep-warm process, maintaining the inside of the pot 5 in a reduced pressure state.

When the heat retention control means 54 determines that the lid 3 has been opened based on a detection signal from the rotation sensor of the hinge shaft 16, it controls the pressure reduction means 28 to close the path and the pressure reduction pump 29 to stop operating. After that, when the heat retention control means 54 determines that the lid 3 has been closed based on a detection signal from the rotation sensor of the hinge shaft 16, it is configured to perform this series of operations again.

When the steaming process is completed and the process moves to the keep-warm process, the display operation control means 59 controls the LCD 76 to turn off the "reserved" LED 77 or the "cooked" LED 78, which have been lit up until that point, and turn on the "keep-warm" LED 79. The display operation control means 59 also controls the LCD 76 to turn on the "freshly cooked" display element 81-3, as shown in Fig. 7(A), and to display the keep-warm time, which is the elapsed time since the start of the keep-warm process, measured by a timing means (not shown), in the keep-warm time display element 81-8. In this embodiment, the "keep warm" LED 79, which is the keep warm display, and the "freshly cooked" display element 81-3, arrow display elements 81-4, 81-5, 81-6, "keep warm" display element 81-7, and keep warm time display element 81-8, which are status display elements that show the state of the rice in the pot 5, are located close to each other, allowing the user to easily know that the rice cooker 1 is keeping warm and the state of the rice in the pot 5 during the keep warm period.

7A shows the display of the display elements 81-3 to 81-8 5 minutes after the transition to the warming step. In the rice cooker 1 of this embodiment, the warming time of the initial warming period _T1 is 30 minutes, and the display operation control means 59 controls the LCD 76 to display the warming time in the warming time display element 81-8 in 1-minute increments until the warming time of 30 minutes has elapsed. This is because the initial warming period _T1 is shorter than the total warming time of, for example, 6 hours, 12 hours, or 24 hours in the warming step, and the freshness of the freshly cooked rice decreases in a short period of time during the initial warming period _T1 . By displaying and checking the elapsed time in 1-minute increments, the user can grasp the deterioration of the taste of the rice in the pot 5 in real time. In this embodiment, the warming time display element 81-8 displays the word "minutes", such as "5 minutes" or "15 minutes", but the present invention is not limited to this, and may display the word "min" or "m", for example.

The display operation control means 59 also controls the LCD 76 to turn on the "freshly cooked" display element 81-3 until the 10 minutes of warming time have elapsed, while keeping the arrow display elements 81-4, 81-5, 81-6 and the "keep warm" display element 81-7 off. This allows the user to intuitively understand at a glance that the rice in the pot 5 is currently in a freshly cooked state.

Figure 7(B) shows the display of the display elements 81-3 to 81-8 15 minutes after the transition to the keep-warm step, and the display operation control means 59 controls the LCD 76 to turn on the "freshly cooked" display element 81-3 and the arrow display element 81-4 from 10 to 15 minutes into the keep-warm time, while keeping the arrow display elements 81-5, 81-6, and the "keep-warm" display element 81-7 off. Figure 7(C) shows the display of the display elements 81-3 to 81-8 19 minutes after the transition to the keep-warm step, and the display operation control means 59 controls the LCD 76 to turn on the "freshly cooked" display element 81-3 and the arrow display elements 81-4 and 81-5 from 15 to 20 minutes into the keep-warm time, while keeping the arrow display element 81-6 and the "keep-warm" display element 81-7 off.

7(D) shows the display of the display elements 81-3 to 81-8 25 minutes after the transition to the keep-warm step, and the display operation control means 59 controls the LCD 76 to light the "freshly cooked" display element 81-3 and the arrow display elements 81-4, 81-5, and 81-6 from 20 to 25 minutes into the keep-warm time, while keeping the "keep-warm" display element 81-7 off. Also, FIG. 7(E) shows the display of the display elements 81-3 to 81-8 29 minutes after the transition to the keep-warm step, and the display operation control means 59 controls the LCD 76 to light the "freshly cooked" display element 81-3, the arrow display elements 81-4, 81-5, and 81-6, and the "keep-warm" display element 81-7 from 25 to 30 minutes into the keep-warm time. In this way, the display operation control means 59 controls the LCD 76 to display the state of the rice in the pot 5 as a pictogram consisting of the "freshly cooked" display element 81-3, the arrow display elements 81-4, 81-5, 81-6, and the "keep warm" display element 81-7. As time passes, the number of arrow display elements 81-4, 81-5, and 81-6 displayed increases, and in addition, the "keep warm" display element 81-7 is also displayed. As a result, the user can intuitively understand at a glance how much time has passed since the initial keep warm period _T1 , which is the "freshly cooked" period after the cooking process is completed, and the specific time can be ascertained from the display of the keep warm time display element 81-8.

To explain the operation during the warm-keeping descending period _T2 , when the warm-keeping initial period _T1 ends and the process moves to the warm-keeping descending period _T2 , the warm-keeping control means 54 lowers the temperature _tR of the rice in the pot 5 and manages the temperature of the pot 5 by controlling the on/off of the heating coil 12 and the body heater 11 according to the temperature detected by the pot sensor 14 so that the temperature remains above 80°C, and also controls the temperature by controlling the on/off of the lid heater 22 according to the temperature detected by the lid temperature sensor 34. Therefore, regardless of the characteristics of the rice cooker 1, the amount of cooked rice in the pot 5, or changes in the environment around the rice cooker 1, the rice can be kept fresh like as if it had just been cooked, even after a certain period of time has passed since the process moved to the warm-keeping step during the warm-keeping descending period _T2 .

On the other hand, the heat retention control means 54 is configured to control the temperature of the pot 5 by controlling the heating coil 12 and the body heater ₁₁ on and off according to the temperature detected by the pot sensor 14 so that the temperature _t3 of the inner side surface of the pot ₅ alternates between a temperature _tH1 higher than the temperature of the _{rice tR and} a temperature _tL1 lower than the temperature of the rice, as in the initial heat retention period _T1 , and to control the temperature of the inner lid 22 by controlling the lid heater 22 on and off according to the temperature detected by the lid temperature sensor 34 so that the temperature t4 of the inner lid 22 facing the pot alternates between a temperature tH2 higher than the temperature of the rice _tR and a temperature tL2 lower than the temperature of the rice. Therefore, by lowering the temperature _tR of the rice in the pot 5 as quickly as possible, it is possible to prevent condensation on the inner side surface of the pot 5 and the inner lid 22 facing the pot, and prevent the soup from dripping onto the rice. As a result, even in the heat retention lowering period _T2, the rice can be kept in a freshly cooked state and maintain a taste equivalent to that of freshly cooked rice.

Fig. 7(F) shows the display of the display elements 81-3 to 81-8 from 35 minutes to 40 minutes after the transition to the keep-warm step, and Fig. 7(G) shows the display of the display elements 81-3 to 81-8 from 55 minutes to 60 minutes after the transition to the keep-warm step. When the initial keep-warm period _T1 ends and the transition to the keep-warm descending period _T2 begins, the display operation control means 59 controls the LCD 76 to light up the "keep-warm" display element 81-7, while turning off the "freshly cooked" display element 81-3, the arrow display elements 81-4, 81-5, 81-6, and the "keep-warm" display element 81-7. This allows the user to see at a glance that the rice in the pot 5 has passed the keep-warm descending period _T2, which is the period for freshly cooked rice. In the rice cooker 1 of this embodiment, the warming time of the warming descending period _T2 is from 30 minutes to 60 minutes, and the display operation control means 59 controls the LCD 76 to display the warming time in 5-minute increments on the warming time display element 81-8 from 30 minutes to 60 minutes. This is to accommodate the fact that, like the initial warming period _T1 , the period of the warming descending period _T2 is short compared to the entire warming time in the warming process, and the freshness of the freshly cooked rice decreases in a short period of time even during the warming descending period _{T2, while the deterioration of the rice is slower than during the initial warming period T1 by} lowering the temperature _tR of the rice in the pot 5 to maintain the freshly cooked state, and allows the user to grasp the deterioration of the taste of the rice in the pot 5 in real time, while preventing unnecessary changes in the display from bothering the user when checking.

To explain the operation during the stable warming period _T3 , when the warming decreasing period _T2 ends and the process moves to the stable warming period _T3 , the warming control means 54 lowers the temperature _tR of the rice in the pot 5 and manages the temperature of the pot 5 by controlling the electrical connection of the heating coil 12 and the body heater 11 according to the temperature detected by the pot sensor 14 so that the temperature is kept at the warming set temperature, for example, 73°C ±3°C, and also controls the temperature by controlling the electrical connection of the lid heater 22 according to the temperature detected by the lid temperature sensor 34. The warming control means 54 calculates the temperature _tR of the rice in the pot 5 from the temperature detected by the pot sensor 14, and when it determines that the temperature _tR of the rice in the pot 5 has dropped below 73°C ±3°C due to the opening and closing of the lid 3, it controls the electrical connection of the heating coil 12 and the body heater 11 and also controls the electrical connection of the lid heater 22 so that the temperature of the rice _tR returns to 73°C ±3°C. Under certain conditions, the temperature _tR of the rice may be temporarily lowered to a temperature not lower than 60° C., which can suppress the Maillard reaction of the rice in the pot 5 and improve the energy-saving performance of the rice cooker 1.

The heat retention control means 54 is configured to manage the temperature of the pot _{5 by controlling the energization of the heating coil 12 and} the body heater _{11 based on the temperature detected by the pot sensor 14 so that the temperature t3 of the inner side of the pot 5 alternates between temperatures tH1 , which} are higher than the temperature of the rice, and temperatures _tL1 , which are lower than the temperature of the rice, similar to the initial heat retention period _T1 and the heat retention decreasing period T2, and to manage the temperature of the inner lid 22 by controlling the energization of the lid heater 22 based on the temperature detected by the lid temperature sensor 34 so that the temperature _t4 of the pot-facing surface of the inner lid 22 alternates between temperatures _tH2 , which are higher than the temperature of the rice, and temperatures _tL2 , which are lower than the temperature of the rice.

If the warming control means 54 determines that the lid 3 has been opened or closed based on a detection signal from the rotation sensor of the hinge shaft 16 during the initial warming period _T1 or the warming decreasing period _T2 , the warming control means 54 may be configured to perform the above-mentioned control for the stable warming period _T3 even if the warming time is within 60 minutes. When the lid 3 is opened and the rice in the pot 5 is loosened, excess moisture is diffused and released from the rice cooker 1 and the temperature _tR of the rice in the pot 5 drops, thereby suppressing the deterioration of taste and the Maillard reaction caused by excess moisture.

Fig. 7(H) shows the display of the display elements 81-3 to 81-8 from 1 hour to 2 hours after the transition to the warming step, and Fig. 7(I) shows the display of the display elements 81-3 to 81-8 from 2 hours to 3 hours after the transition to the warming step. When the warming drop period _T2 ends and the warming stable period _T3 begins, the display operation control means 59 controls the LCD 76 to display the warming time in the warming time display element 81-8 in one-hour increments after 60 minutes of warming time has elapsed. This is to accommodate the fact that the temperature _tR of the rice in the pot 5 is lower than during the warming drop period _T2 , and the deterioration of the rice becomes even slower, and to prevent unnecessary changes in the display from bothering the user when checking. In this embodiment, the warming time display element 81-8 displays the word "time", such as "1 hour" or "2 hours", but the present invention is not limited to this, and may display the word "Hr" or "H", for example. Also, the display operation control means 59 controls the LCD 76 to light the "Keep Warm" display element 81-7, as in the case of the warm-keeping descending period _T2 , while turning off the "Freshly Cooked" display element 81-3, the arrow display elements 81-4, 81-5, 81-6 and the "Keep Warm" display element 81-7, thereby enabling the user to see at a glance that the rice in the pot 5 has passed the initial warm-keeping period _T1 or the warm-keeping descending period _T2 .

As described above, the rice cooker 1 of this embodiment comprises a pot 5 that contains rice and water as the food to be cooked, a heating coil 12 and a body heater 11 as heating means for heating the pot 5, a heating control means 40 as control means for controlling the heating coil 12 and the body heater 11, and a display unit 18 as display means for displaying information related to cooking. The heating control means 40 controls the heating coil 12 and the body heater 11 to heat the pot 5 and perform a rice cooking process in which the food to be cooked is cooked, and a warming process in which the rice cooked in the rice cooking process is kept warm, in that order. The display unit 18 is configured to have a "keep warm" LED 79 as a warming display unit that indicates that the warming process is being performed, and a "freshly cooked" display element 81-3, arrow display elements 81-4, 81-5, 81-6, a "keep warm" display element 81-7, and a keep warm time display element 81-8 as status display units that display the state of the rice during the keep warm process. Therefore, by checking the display unit 18, the user can easily see that the rice cooker 1 is keeping the rice warm and the state of the rice in the pot 5 while it is being kept warm.

In addition, in the rice cooker 1 of this embodiment, the display of the "freshly cooked" display element 81-3, the arrow display elements 81-4, 81-5, 81-6, and the "keep warm" display element 81-7 changes to light or turn off depending on changes in the condition of the rice in the pot 5, such as the keep warm time, which is the time elapsed since the keep warm process began, and the keep warm time display element 81-8 also changes. This allows the user to grasp the deterioration in the taste of the rice in the pot 5 since the keep warm process began.

In the rice cooker 1 of this embodiment, the initial warming period _T1 and the warming decreasing period _T2, during which the warming time is within 60 minutes, are considered to be the freshly cooked period, and the user can grasp that the rice in the pot 5 is cooked before the stable warming period _T3 and the rice temperature _tR reaches 73°C ±3°C.

In addition, the rice cooker 1 of this embodiment is further equipped with a pot sensor 14 as a pot temperature detection means for detecting the temperature of the pot 5, and the heating control means 40 controls the heating coil 12 and the body heater 11 so as to maintain the temperature of the rice in the pot 5 at a predetermined temperature of 80°C or higher during the initial warming period _T1 and the warming descending period _T2 , which are predetermined elapsed times within 60 minutes after the start of the warming process, and the display operation control means 59 displays the state of the rice in the pot 5 during the initial warming period _T1 and the warming descending period _T2 by means of a pictogram displayed by the "freshly cooked" display element 81-3, arrow display elements 81-4, 81-5, 81-6 and the "warm" display element 81-7.

By configuring it in this way, rice can be kept fresh like freshly cooked even in the warming descending period T2, a certain period of time after the rice has entered the warming process, regardless of the characteristics of the rice cooker ₁ , the amount of cooked rice in the pot 5, or changes in the environment around the rice cooker 1. Furthermore, the user can intuitively understand at a glance how much time has passed since the warming initial period _T1 and the warming descending period _T2, which are the "freshly cooked" periods after the rice cooking process ends, and can grasp the specific time from the display of the warming time display element 81-8.

In addition, the rice cooker 1 of this embodiment further comprises an inner lid 22 which covers the upper opening of the pot 5, a lid heater 33 as a lid heating means for heating the inner lid 22, and a lid temperature sensor 34 as a lid temperature detection means for detecting the temperature of the inner lid 22, and the lid heater 33 is controlled by heating control means 40, which controls the lid heater 33 so that the temperature _t4 of the pot-facing surface of the inner lid 22 is on average higher than the temperature _tR of the rice during the initial warming period _T1 and the warming decrease period _T2 , which are predetermined elapsed times within 60 minutes after the start of the warming process.

This configuration prevents condensation on the inside sides of the pot 5 and the pot-facing surface of the inner lid 22, preventing the sauce from dripping onto the rice, and allowing the rice to remain in a freshly cooked state and maintain a flavor equivalent to that of freshly cooked rice.

The rice cooker 1 of this embodiment further includes a pressure reducing means 28 for degassing the inside of the pot 5 by lowering the pressure therein below normal atmospheric pressure while the top opening of the main body 2 that houses the pot 5 is covered with the lid 3, and is configured to degas the inside of the pot 5 throughout the initial warming period _T1 , the warming decreasing period T2 _, and the stable warming period _T3 during the warming process. This makes it possible to prevent early browning due to the Maillard reaction after heating for freshly cooked rice, and makes it possible to prevent deterioration of the rice in the pot 5 during the subsequent warming decreasing period _T2 and stable warming period _T3 while the rice is being kept warm, as opposed to keeping the rice at a high temperature to maintain the freshly cooked state immediately after the start of the warming process.

In the rice cooker 1 of this embodiment, the warming time is displayed in 1-minute or 5-minute units, which are units shorter than 1 hour, during the initial warming period _T1 and the warming descending period _T2 , which are predetermined periods within 60 minutes of the warming time that has elapsed since the start of the warming process, and the warming time is displayed in hours during the stable warming period _T3 after the warming descending period _T2 and the stable warming period _T3 have elapsed. In the warming process, the initial warming period _{T1 and the warming descending period T2 are short periods compared to the total warming time of, for example, 6 hours, 12 hours, or 24 hours, and the freshness of the freshly cooked rice deteriorates in a short period of time during the initial warming period T1 and the} warming descending period _T2 , but this configuration allows the user to grasp the deterioration of the taste of the rice in the pot 5 in real time.

Figures 9 to 11 show a second embodiment of the rice cooker of the present invention. In this embodiment, the display operation control means 59 controls the LCD 76 to display a keeping-warm temperature display element 81-21 in addition to the display elements described in the first embodiment as display elements that show the state of the rice during the keeping-warm process.

9 is a top view of the main parts of the rice cooker 1 of this embodiment. In the LCD 76, the keep-warm temperature display element 81-21 is arranged next to the right of the keep-warm time display element 81-8, and displays the temperature _tR of the rice in the pot 5. Other points are the same as those in the first embodiment, so the explanation will be omitted.

9 shows the operation unit 19 and the display unit 18 9 minutes after the transition to the warming step. To explain the operation during the warming step, the display operation control means 59 receives the temperature _tR of the rice in the pot 5 calculated from the temperature detected by the pot sensor 14 from the warming control means 54, and controls the LCD 76 to display the rice temperature _tR on the warming temperature display element 83-21. As described in the first embodiment, the display operation control means 59 controls the LCD 76 to display the warming time on the warming time display element 81-8, and therefore the display operation control means 59 controls the LCD 76 to display the warming temperature together with the warming time. As described above, there is a close relationship between the temperature _tR of the rice in the pot 5 and the freshness of the freshly cooked rice, so by displaying the temperature _tR of the rice, the user can grasp the state of the freshness of the freshly cooked rice. Furthermore, the display operation control means 59 of this embodiment controls the LCD 76 to display the warming temperature in 1° C. increments until the warming time has elapsed for 60 minutes. This is because, like the warming time in the first embodiment, in the warming process, the periods of the initial warming period _T1 and the warming decreasing period _T2 as the "freshly cooked" period are short compared to the entire warming time, and the freshness of the freshly cooked rice deteriorates in a short period of time during the initial warming period _T1 and the warming decreasing period _T2 , allowing the user to grasp the deterioration in the taste of the rice in the pot 5 in real time.

In this embodiment, the warming temperature is displayed in 1°C increments until 60 minutes of warming time has elapsed, but the temperature units may be determined arbitrarily, for example, in 2°C increments such as 98°C → 96°C → 94°C, or in 5°C increments such as 95°C → 90°C → 85°C. In this case, for example, when the unit is 2°C, when the rice temperature _tR is between 100°C and 98°C, it is displayed as 98°C, indicating that the actual rice temperature _tR is within the temperature unit range, in this case, the rice temperature _tR plus or minus 2°C.

10(A) and 10(B) show the display of the display elements 81-3 to 81-8 and 81-21 from 2 hours to ₃ hours after the transition to the warming process. For example, when the display operation control means 59 receives from the warming control means 54 information that the rice temperature _tR has reached the vicinity of the warming set temperature of 73°C (e.g., 80°C) after the transition to the warming stable period T3, the display operation control means 59 controls the LCD 76 to display the warming set temperature of 73°C on the warming temperature display element 83-21 as shown in FIG. 10(A). Alternatively, as shown in FIG. 10(B), the display operation control means 59 controls the LCD 76 to turn off the warming temperature display element 83-21. Therefore, in either case of FIG. 10(A) or (B), the user can know at a glance that the rice in the pot 5 has passed the warming initial period _T1 or the warming decreasing period _T2 .

11(A) and (B) show the display of display elements 81-3 to 81-8 and 81-21 when, after the transition to the keep-warm process, the supply of power to rice cooker 1 is stopped due to a power outage or the like, all operations of heating means 52 are stopped, and the rice temperature _tR drops to 60°C, and 15 minutes have passed since power was restored to rice cooker 1 5 hours later. When display operation control means 59 receives from keep-warm control means 54 information that rice temperature _tR has fallen significantly below the keep-warm set temperature of 73°C (for example, below 65°C), it controls LCD 76 to display the received current rice temperature _tR on keep-warm temperature display element 83-21, as shown in FIG. 11(A) and (B). 10(A), the display operation control means 59 controls the LCD 76 to display, as the warming time, 15 minutes, which is the time that has elapsed since the power supply was started and the warming process was resumed, on the warming time display element 81-8. Alternatively, as shown in Fig. 10(B), the display operation control means 59 controls the LCD 76 to display, as the warming time, 5 hours, which is the time that has elapsed since the warming process was started, on the warming time display element 81-8. Therefore, in both cases of Fig. 11(A) and (B), the user can see at a glance that the supply of power to the rice cooker 1 has been stopped and then restored, and that the temperature of the rice in the pot 5 has temporarily dropped.

As described above, in the rice cooker 1 of this embodiment, the state of the rice displayed by the "freshly cooked" display element 81-3, the arrow display elements 81-4, 81-5, 81-6, the "keep warm" display element 81-7, the keep warm time display element 81-8 and the keep warm temperature display element 83-21 as status display sections is configured to be at least one of the temperature _tR of the rice in the pot 5 and the keep warm temperature, which is the elapsed time since the start of the keep warm process, and since there is a close relationship between the temperature _tR of the rice in the pot 5 and the freshness of freshly cooked rice, by displaying the temperature _tR of the rice, the user can grasp the freshness of the freshly cooked rice.

Figure 12 shows a third embodiment of the rice cooker of the present invention. In this embodiment, the display operation control means 59 controls the LCD 76 to display the "Power outage occurred" display element 81-22 and the "Re-cooking" display element 81-23 as display elements indicating that the power supply to the rice cooker 1 has been stopped, in addition to the display elements described in the first embodiment.

Figures 12 (A), (B), and (C) are top views of the main parts of the LCD 76 of this embodiment. In the LCD 76, the "Power outage occurred" display element 81-22 and the "Re-cooking" display element 81-23 are arranged side by side above the "Freshly cooked" display element 81-3, the arrow display elements 81-4 to 81-6, and the "Keep warm" display element 81-7. Other points are the same as in the first embodiment, so explanations will be omitted.

12(A) shows the display of display elements 81-3 to 81-8, 81-22, and 81-23 from one hour to two hours after the power supply to rice cooker 1 is stopped for one minute or more during the rice cooking process and then power supply is resumed, and rice cooking is resumed and the process moves to the keep-warm process. When the display operation control means 59 detects whether or not power is being supplied to the display and operation control means 46, and determines that a power outage that affects the cooked state of the rice in pot 5 has occurred during the rice cooking process, such as a power outage of one minute or more, the display operation control means 59 controls the LCD 76 to light only the "keep warm" display element 81-7 and not light up the "freshly cooked" display element 81-3 or the arrow display elements 81-4 to 81-6, even when the rice cooking process ends and the process moves to the keep-warm process, and to display the keep-warm time on the keep-warm time display element 81-8. At this time, as shown in FIG. 12(A), the LCD 76 may be controlled to display both the "Power outage occurred" display element 81-22, which indicates that a power outage occurred during the cooking process, and the "Restart cooking" display element, which indicates that cooking resumed after the power supply was resumed.

12B shows the display of display elements 81-3 to 81-8, 81-22, and 81-23 when the warm-keeping time has elapsed from ₁ hour to 2 hours, in a state where the power supply to rice cooker 1 is resumed after being stopped for 5 minutes or more during the initial warm-keeping period T1 and the warm-keeping descending period _T2 , which are predetermined times within 60 minutes of the warm-keeping time _. When the display operation control means 59 detects the presence or absence of power supply to the display and operation control means 46 and determines that a power outage that may affect the deterioration of the rice in pot 5, such as a power outage of 5 minutes or more, has occurred during the initial warm-keeping period _T1 and the warm-keeping descending period T2, the display operation control means 59 controls the LCD 76 to turn off the "freshly cooked" display element 81-3 and the arrow display elements 81-4 to 81-6, turn on only the "warm" display element, and display the warm-keeping time on the warm-keeping time display element 81-8 when the power supply is resumed and the warm-keeping process is resumed. At this time, as shown in FIG. 12B, the LCD 76 may be controlled to display a display element 81-22 "power outage occurred" indicating that a power outage has occurred during the process.

Figure 12 (C) shows the display of display elements 81-3 to 81-8, 81-22, and 81-23 when the keep-warm process is started manually without performing the rice cooking process and the keep-warm time has elapsed from 1 hour to 2 hours. When performing the keep-warm process manually, for example, by operating the keep-warm key 67 on the operation unit 19, the operation signal is received by the operation unit control means 58, and the condition setting means 60 sends information on the heating pattern corresponding to the keep-warm process to the heating control means 40. In response to this, the heating control means 40 performs a keep-warm operation on the rice in the pot 5 using the keep-warm control means 54 built into the control IC 42 in accordance with the heating pattern of the keep-warm process. The display operation control means 59 also controls the LCD 76 to turn on the "keep warm" LED 79, leave the "freshly cooked" display element 81-3 and the arrow display elements 81-4 to 81-6 off, turn on only the "keep warm" display element, and display the keep warm time on the keep warm time display element 81-8.

Figure 13 shows a fourth embodiment of the rice cooker of the present invention. In this embodiment, the display operation control means 59 controls the LCD 76 to change the display element 81-3 of "freshly cooked" described in the second embodiment, which is a display element showing the state of the rice during the warming process, to a display that indicates the state of the rice by its name, such as "hot" or "shiny."

Figures 13(A) and (B) are top views of the main parts of the LCD 76 of this embodiment. Figure 13(A) shows the display of the display elements 81-3' and 81-4 to 81-8 10 minutes after the transition to the keep-warm step. The display operation control means 59 controls the LCD 76 to turn on the "freshly cooked" display element 81-3 while keeping the arrow display elements 81-4, 81-5, 81-6 and the "keep-warm" display element 81-7 off until the 5-minute keep-warm time has elapsed.

After that, as shown in FIG. 13(A), the display operation control means 59 controls the LCD 76 to change the display element 81-3 of "freshly cooked" to the display element 81-3' of "hot" for the 5-10 minute keep-warm time. FIG. 13(B) shows the display of the display elements 81-3" and 81-4 to 81-8 15 minutes after the start of the keep-warm process, and the display operation control means 59 controls the LCD 76 to change the display element 81-3' of "hot" to the display element 81-3" of "shiny" for the 5-10 minute keep-warm time and to turn on the arrow display element 81-4, while keeping the arrow display elements 81-5 and 81-6 and the "keep-warm" display element 81-7 off. This allows the user to easily grasp at a glance the current state of freshness of the freshly cooked rice in the pot 5 and the state of deterioration in taste. In this embodiment, the descriptions in the display element 81-3 are "freshly cooked," "hot," and "shiny," but the present invention is not limited to this, and any display that allows the user to understand the freshness of the freshly cooked rice in the pot 5 may be used.

As described above, in the rice cooker 1 of this embodiment, the state of the rice is displayed by naming the state of the rice in the pot 5, such as the "freshly cooked" display element 81-3, the "hot" display element 81-3', and the "shiny" display element 81-3'', and the state of the rice in the pot 5 is displayed pictograms consisting of the "freshly cooked" display element 81-3, the arrow display elements 81-4, 81-5, 81-6, and the "keep warm" display element 81-7. This allows the user to easily grasp at a glance the current state of freshness of the rice in the pot 5 and the state of any deterioration in taste.

Figures 9 to 14 show a fifth embodiment of the rice cooker of the present invention. In this embodiment, the display and operation control means 46 further includes a transmission unit 86 capable of communicating with an information terminal, and the state of the rice, which is displayed, for example, by the "freshly cooked" display element 81-3, the arrow display elements 81-4, 81-5, and 81-6, and the "keep warm" display element 81-7, can be confirmed on this information terminal.

Figure 14 is a block diagram showing the electrical configuration of the rice cooker 1 of this embodiment. In the figure, the display and operation control means 46 further includes a transmission unit 86. The other points are the same as those of the first embodiment, so the explanation will be omitted.

Conventionally, there is known technology for checking the operating status of the rice cooker 1, such as whether the power is off, whether the timer is on, whether the rice is cooking, whether it is keeping warm, etc., using an information terminal such as a smartphone. In this embodiment, in addition to displaying the operating status of the rice cooker 1 on an information terminal at the user's hand in a location away from the rice cooker 1, the system is also configured to display the freshness of the rice in the pot 5.

Next, the operation of the rice cooker 1 configured as above will be described. The display and operation control means 46 transmits information from the transmission unit 86 to the information terminal when the operation of the rice cooker 1 changes, for example, when the rice cooker 1 is turned on, when the cooking process starts, when it transitions to the keep-warm process, etc. The information transmitted at this time is information displayed by the display unit 18, such as the "reservation" LED 77, the "cooking" LED 78, the "keep-warm" LED 79, the clock display element 81-1, the cooked rice reservation display element 81-2, as well as the "freshly cooked" display element 81-3 which displays the state of the rice in the keep-warm process, the arrow display elements 81-4, 81-5, 81-6, the "keep-warm" display element 81-7, and the keep-warm time display element 81-8. By receiving this information on the user's information terminal and displaying it on the information terminal, the user can grasp the state of freshness of the freshly cooked rice in the pot 5 on the information terminal at hand, and by notifying the user from the information terminal in conjunction with a notification from the rice cooker 1 that cooking is complete, for example, it is possible to prevent the rice from being left for a long time after cooking is complete. As a result, the risk of the user missing the timing to eat freshly cooked rice can be reduced.

In addition to the information to be transmitted, such as the state of freshness of the rice in the pot 5 during the warming process, and the warming state, such as the warming time and warming temperature, information on the amount of rice in the pot 5 during the warming process may also be transmitted. A method of detecting the amount of rice in the pot 5 during the warming process is well known, in which a weight sensor is provided in the rice cooker 1 and a change in weight of the rice in the pot 5 is measured. The applicant of the present application has also proposed a method of detecting the amount of rice in the pot 5 using a control pattern for the body heater 11 and the lid heater 33 (Reference: JP 05-228052 A), and a method of providing a camera in the rice cooker 1 and using this camera to photograph the amount of rice in the pot 5 when the lid 3 is closed (Reference: JP 2018-082844 A).

In this embodiment, the transmitter 86 is used, but the transmitter 86 may be a transceiver. In this case, the information about the rice cooker 1 described above may be configured to be sent to the information terminal when the user sends the information to the rice cooker 1 using an information terminal, allowing the user to know the operating status of the rice cooker 1 and the state of the rice in the pot 5 at any time. In this embodiment, the rice cooker 1 is configured to be able to communicate with an information terminal, but it may also be configured to be able to communicate with a smart speaker or television, and the completion of rice cooking can be announced by voice in conjunction with these smart speakers or televisions.

As described above, the rice cooker 1 of this embodiment further includes a transmission unit 86 capable of communicating with an information terminal such as a smartphone, and is configured to transmit information on the state of the rice in the pot 5 after the transition to the keep-warm process, such as the "freshly cooked" display element 81-3, the arrow display elements 81-4, 81-5, 81-6, the "keep warm" display element 81-7, and the keep-warm time display element 81-8, to the information terminal. This allows the user to grasp the freshness of the freshly cooked rice in the pot 5 using an information terminal at hand.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, the configurations characteristic of the first to fifth embodiments may be combined. Furthermore, the numerical values exemplified in the embodiments are merely examples, and may be modified as appropriate depending on the specifications of the rice cooker, etc.

1 Rice cooker 2 Main body 3 Lid 5 Pot 11 Body heater (heating means)
12 Heating coil (heating means)
14 Pot sensor (pot temperature detection means)
18 Display section (display means)
22 Inner lid 28 Pressure reducing means 33 Lid heater (lid heating means)
34 Lid temperature sensor (lid temperature detection means)
40 Heating control means (control means)
81-3 "Freshly cooked" labeling elements ( multiple labels )
81-3' Display element for "hot" ( multiple displays )
81-3" Display element of "shiny" ( multiple displays )
81-4 Arrow display element ( multiple displays )
81-5 Arrow display element ( multiple displays )
81-6 Arrow display element ( multiple displays )
81-7 Display element for "warm" ( multiple displays )
81-8 Warm time display element ( warm time )
83-21 Insulation temperature display element ( multiple displays )
86 Transmitter T ₁ Initial warming period (freshly cooked rice period, warming process)
_T2 Heat retention decreasing period (freshly cooked period, heat retention process)
T ₃ Heat retention stable period (heat retention process)
t _R temperature of rice

Claims (8)

A pot for storing rice and water as food to be cooked;
A heating means for heating the pan;
A control means for controlling the heating means;
A display means for displaying information related to cooking;
A pan temperature detection means for detecting the temperature of the pan,
The control means controls the heating means so as to heat the pot and perform a rice cooking process in which the food to be cooked is cooked, and a warming process in which the rice cooked in the rice cooking process is kept warm in that order.
The heat retention step includes:
An initial stage of keeping the rice warm within 30 minutes after the end of the rice cooking process , in which the temperature of the rice is 90°C or higher;
a heat retention lowering period in which the temperature of the rice is lowered after the initial heat retention period, the heat retention period being within 60 minutes after the end of the rice cooking process ;
and a heat retention stable period in which the rice cooled in the heat retention decreasing period is kept at a predetermined temperature.
The control means, during the temperature keeping/lowering period, lowers the temperature while controlling the power supply/disconnection of the heating means based on the temperature detected by the pan temperature detection means ;
The display means displays, in the warming process, a warming time, which is the elapsed time since the start of the warming process, and a state of change from the initial warming period to the warming decreasing period and the stable warming period in the warming process, in a plurality of displays . An inner lid for covering an upper opening of the pot;
A lid heating means for heating the inner lid;
A lid temperature detection means for detecting the temperature of the inner lid is further provided.
The lid heating means is controlled by the control means,
The rice cooker according to claim 1, characterized in that the control means controls the power on/off of the lid heating means based on the temperature detected by the lid temperature detection means so that a temperature higher and a temperature lower than the temperature of the rice are alternately repeated during the heat retention decreasing period. 3. The rice cooker according to claim 1, wherein the initial warming period and the warming decreasing period are a period of a predetermined elapsed time within 60 minutes from the start of the warming process, or a freshly cooked period during which the temperature of the rice in the warming process is equal to or higher than a predetermined temperature. The rice cooker according to claim 1, characterized in that the control means controls the heating means so as to maintain the temperature of the rice at a predetermined temperature of 80°C or higher for a predetermined period of time within 60 minutes after the start of the warming process. An inner lid for covering an upper opening of the pot;
A lid heating means for heating the inner lid;
A lid temperature detection means for detecting the temperature of the inner lid is further provided.
The lid heating means is controlled by the control means,
The rice cooker according to claim 4, characterized in that the control means controls the lid heating means so as to make the temperature of the inner lid higher on average than the temperature of the cooked rice during a predetermined period of time within 60 minutes after the start of the warming process. The pot further includes a pressure reducing means for degassing the inside of the pot by lowering the pressure inside the pot to a pressure lower than normal atmospheric pressure when the lid is covering the top opening of the main body that contains the pot.
6. The rice cooker according to claim 1, wherein the inside of the pot is deaerated during the warming step. 2. The rice cooker according to claim 1, wherein the display means displays the warming time in units of less than one hour during a predetermined period of time that is within 60 minutes after the start of the warming process, and displays the warming time in units of hours after the predetermined period of time has elapsed. Further comprising a transmitting unit capable of communicating with an information terminal,
8. The rice cooker according to claim 1, further comprising a configuration in which information on the plurality of displays after the rice cooker has been switched to the keep-warm step is transmitted to the information terminal.

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