rice cooker

Abstract

We provide a rice cooker that can achieve both enhanced water absorption and excellent gloss and texture in cooked rice. [Solution] The rice cooker of the present invention is configured to sequentially perform the following steps: a soaking cooking step in which the temperature of the rice to be cooked is raised to a temperature at which the rice does not gelatinize, and a heating step in which the heating coil 11 is started to be driven from a state of atmospheric pressure inside the pot 4 to heat the pot 4.

Description

[Technical Field]

[0001] This invention relates to a rice cooker that performs a soaking and cooking process to promote water absorption of rice placed in the pot. [Background technology]

[0002] Regarding this type of rice cooker, for example, the applicant of this application provides a heating coil (12) for heating a pot (5) containing rice and water as the contents to be cooked, and a depressurizing pump (29) for reducing the pressure inside the pot (5). In the soaking and cooking process, the depressurizing pump (29) is operated continuously to create a vacuum inside the sealed pot (5), and the heating coil (12) is controlled to heat the pot (5) to promote water absorption of the rice. At the same time, the amount of rice to be cooked in the pot (5) is calculated from the time it takes to reach a predetermined temperature and the amount of heating. B Heat the pot (5) until it reaches the set time (T B ) only the set temperature (t B The proposed method involves a second soaking process that maintains the moisture content of the rice to promote water absorption, followed by a second soaking process, and then the second soaking process, which are carried out in sequence. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-159641 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] If the pot (5) is heated at the start of the soaking and cooking process, the surface of the rice to be cooked will absorb too much water, potentially resulting in a sticky surface and a deterioration in the gloss and texture of the cooked rice. Also, if the temperature of rice is raised before water absorption, the surface tends to crack and the starch tends to dissolve more easily. If the temperature of the rice to be cooked is raised from the beginning of the soaking and cooking process, the rice may crack, resulting in sticky rice and a deterioration in the gloss and texture of the cooked rice.

[0005] Therefore, in view of the above circumstances, the present invention aims to provide a rice cooker that can achieve both improved water absorption and good gloss and texture of cooked rice. [Means for solving the problem]

[0006] The rice cooker of the present invention is capable of sequentially performing a soaking and cooking process, a boiling and heating process, a boiling and continuing process, and comprises a heating means for heating a pot containing rice and water as the food to be cooked, and a depressurization means for reducing the pressure inside the pot, wherein the soaking and cooking process includes a first soaking process in which the depressurization operation is performed by the depressurization means to reduce the pressure inside the pot, while the heating means is not driven, and a second soaking process in which, at the start of the process, the heating means is driven to heat the pot, and the depressurization operation is performed, and these are performed in sequence. [Effects of the Invention]

[0007] According to the present invention, water can be absorbed deep into the rice grains, further improving the luster and texture of the cooked rice. Therefore, it is possible to achieve both enhanced water absorption and improved luster and texture of the cooked rice. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a rice cooker showing one embodiment of the present invention. [Figure 2] The same as above, this is a vertical cross-section of the rice cooker. [Figure 3] The above diagrams show a cross-sectional view of the inner frame and heating coil, and a plan view from the bottom side. [Figure 4] The same as above, this is a block diagram showing the electrical configuration of a rice cooker. [Figure 5] The same as above, this is a top view of the LCD displaying the top screen. [Figure 6] The graph above shows the changes over time in the temperature detected by the pot temperature sensor, the output of the heating coil, and the pressure detected by the pressure sensor during the rice cooking process. [Figure 7] It is a graph showing the change over time of the pot temperature in the capacity determination step according to the amount of the object to be cooked rice, for a conventional rice cooker and the rice cooker of the present embodiment. [Figure 8] Same as above, it is an explanatory diagram of the rice cooker and respective thermographic images when tap water and degassed water are boiled. [Figure 9] It is a graph showing the change over time of the detected temperature of the pot temperature sensor, the output of the heating coil, and the detected pressure of the pressure sensor in the rice cooking process of a rice cooker showing a modified example of the embodiment of the present invention. [Figure 10] It is a graph showing the change over time of the detected temperature of the pot temperature sensor, the output of the heating coil, and the detected pressure of the pressure sensor in the rice cooking process of a rice cooker showing a further modified example of the embodiment of the present invention.

Mode for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the rice cooker in the present invention will be described with reference to the accompanying drawings. In all these drawings, common parts will be given common reference numerals.

[0010] Figs. 1 to 8 show an embodiment of the rice cooker in the present invention. First, the overall configuration of the rice cooker will be described based on Figs. 1 and 2. 1 is the main body, which has a substantially rectangular shape with the front and rear, left and right sides facing each other when viewed from above, and the upper surface is open. 2 is a lid that covers the upper surface opening of the main body 1 in an openable and closable manner. Similar to the main body 1, it has a substantially rectangular shape with the front and rear, left and right sides facing each other when viewed from above, and the upper surface is configured to be substantially flat. The main body 1 has a pot accommodating portion 3 with an open upper surface. When the lid 2 is opened, a bottomed pot 4 as a container for accommodating water and rice, which are the objects to be cooked rice, is detachably accommodated in the pot accommodating portion 3. The pot accommodating portion 3 is configured by combining a bowl-shaped resin inner frame 5 and the like, and is formed in an overall bottomed cylindrical shape.

[0011] The pot 4 is made primarily of aluminum 7, which has good thermal conductivity, and a heating element 8 made of a magnetic metal plate such as ferritic stainless steel is joined to the lower side and bottom of the outer surface of the main material 7. In addition, a heating coil 11 is provided on the outer surface of the inner frame 5, which faces the bottom surface of the pot 4 from the lower side surface, as a heating means for electromagnetic induction heating of the heating element 8 of the pot 4. When a high-frequency current is supplied to the heating coil 11, the heating element 8 of the pot 4 heats up due to the alternating magnetic field generated from the heating coil 11, and the contents of the pot 4 are heated during cooking and warming. The heating coil 11 will be explained in detail later. A pot sensor 12, which serves as a means for detecting the pot temperature, is positioned in the center of the bottom of the inner frame 5 so as to make elastic contact with the bottom surface of the outer surface of the pot 4.

[0012] A hinge 13 is provided at the rear of the lid 2, which serves as the connection point with the main body 1. A lid operating body 14 is also exposed on the front upper surface of the lid 2. When this lid operating body 14 is pressed, the engagement between the main body 1 and the lid 2 is released, and the lid 2 opens around the hinge axis of the hinge 13 by a hinge spring 10 located at the upper rear of the main body 1.

[0013] A steam vent 15 is provided on the rear upper surface of the lid 2 to discharge steam generated from the food being cooked in the pot 4 to the outside of the rice cooker. In addition to the steam vent 15 and the lid operating unit 14, the top surface of the lid 2 is also provided with a display means 18 consisting of an LCD (Liquid Crystal Display) 16 as a screen display unit and an LED (Light Emitting Diode) display unit 17 as a status display unit for displaying various information related to rice cooking, and an operating means 19 consisting of a touch sensor and positioned above the LCD 16 for starting rice cooking, selecting the time and cooking course, etc. A control PC (Printed Circuit) board 21 equipped with a display / operation control means 51 (see Figure 4) for controlling operations and displays is positioned on the lower surface of the display means 18 and the operating means 19.

[0014] The LED display unit 17 displays the actual status of the rice cooker. In this embodiment, the "Reservation" LED display unit lights up when a reservation setting is made, the "Keep Warm" LED display unit lights up when the keep-warm state is activated, the "Vacuum" LED display unit lights up when the inside of the pot 4 is reduced to a pressure lower than atmospheric pressure by the depressurization means 38 (described later), and the "Pressure" LED display unit lights up when the inside of the pot 4 is pressurized from the time pressure starts to build up inside the pot 4 during cooking until the rice is cooked. Therefore, even when the backlight of the LCD 16 is dimmed, the user can understand the current status of the rice cooker at a glance by checking the LED display unit 17. The color of the light when each LED display unit of the LED display unit 17 lights up may be different, allowing the user to understand the current status of the rice cooker at a glance. In this embodiment, the LED display unit 17 is located directly in front of the LCD 16, but it may be located at a distance from the LCD 16. Alternatively, the LED display unit 17 may be omitted, and the content of the LED display unit 17 may be displayed on the LCD 16.

[0015] The operating means 19, which consists of touch sensors, is configured such that, for example, multiple touch keys are arranged, each consisting of a transparent electrode portion made of conductive polymer and a contact portion connected to the control PC board 21, connected by pattern wiring. By touching one of the multiple button display portions shown on the LCD 16, the touch key located above that button display portion and corresponding to that button display portion is touched, and that button display portion is selected.

[0016] In this way, considering user operability and safety, the lid operating element 14 is positioned on the upper front side of the rice cooker, which is closer to the user, and the steam vent 15 is positioned on the upper rear side of the rice cooker, which is further away from the user. This allows for ample space on the upper surface of the lid 2 between the lid operating element 14 and the steam vent 15 to accommodate the display means 18, and thus allows for a larger display means 18 and the operating means 19 positioned above it, thereby improving the visibility of the display means 18 and the operability of the operating means 19. Furthermore, on the upper surface of the lid 2, apart from the operating means 19 above the LCD 16, there are no physical keys or buttons such as a cooking key or off key that were present in conventional rice cookers. Since the rice cooker is operated solely by the operating means 19, the effort of searching for buttons during operation is eliminated, improving operability. In addition, a very sleek appearance can be achieved, and the space occupied by precision components such as the display means 18 and operating means 19 can be made compact. Furthermore, by excluding physical keys and buttons, the top surface of the lid 2 can be made almost flat, making it easier to wipe clean and improving ease of maintenance.

[0017] An inner lid assembly 23, which serves as the lower component of the lid 2, is provided on the underside of the lid 2. The inner lid assembly 23 is made of a metal material and has a disc shape with approximately the same diameter as the upper opening of the pot 4. It comprises an inner lid 24 that covers the upper opening of the pot 4, a lid packing 25 which is an elastic member provided around the entire outer circumference of the inner lid 24 to seal the space between the inner lid 24 and the pot 4, and a pressure regulating unit 26 that adjusts the internal pressure of the pot 4. The annularly formed lid packing 25, as shown in Figure 2, contacts the upper surface of the pot 4, which is the opening, when the lid 2 is closed, sealing the gap between the pot 4 and the inner lid 24 and sealing in the steam generated from the pot 4.

[0018] Inside the lid 2, a lid opening / closing detection means 27 is provided near the hinge 13 to detect the opening and closing of the lid 2. The lid opening / closing detection means 27 can be of any detection type, such as optical, mechanical, or magnetic, as long as it can output a detection signal corresponding to the opening and closing of the lid 2. Inside the lid 2, a lid heater 31 is provided as a lid heating means for heating the inner lid 24, and a thermistor-type lid temperature sensor 32 is provided for controlling the temperature of the inner lid 24 using the lid heater 31. Inside the lid 2, a steam discharge path 33 is formed, connecting the steam vent 15 and the pressure regulating unit 26, as a passage for releasing steam generated in the pot 4 to the outside.

[0019] The pressure regulating unit 26 is equipped with a pressure regulating valve 34 that opens and closes the steam discharge path 33 between the inside of the pot 4 and the steam vent 15. The pressure regulating valve 34 is ball-shaped and works in conjunction with a solenoid 35 installed inside the lid 2. The solenoid 35 rotates the pressure regulating valve 34 so as to open the steam discharge path 33 when releasing steam from inside the pot 4 to the outside, and close the steam discharge path 33 when pressurizing or depressurizing the inside of the pot 4. When pressurizing, the food being cooked inside the pot 4 is heated by high-frequency current applied to the heating coil 11, causing the food to boil and generate steam. When this steam fills the inside of the pot 4 and the internal pressure of the pot 4 reaches a predetermined value, the pressure regulating valve 34 opens the steam discharge path 33 against its own weight, thereby maintaining the pressure inside the pot 4 at or above atmospheric pressure. A pressure sensor 36 (see Figure 4) is also installed inside the lid 2, facing the pressure regulating unit 26, to detect the pressure inside the pot 4.

[0020] 38 is a pressure reducing means for lowering the pressure inside the pot 4 to below normal atmospheric pressure when the lid 2 is closed on the main body 1. The pressure reducing means 38 reduces the internal pressure of the sealed pot 4 by energizing the solenoid 35 after the pot 4 is placed in the pot housing 3 and the lid 2 is closed, causing the pressure regulating valve 34 to block the steam discharge path 33. Furthermore, when the pressure inside the pot 4 falls below a certain value below atmospheric pressure, the operation of the pressure reducing pump 39, which is the operating source of the pressure reducing means 38, is stopped, and the inside of the pot 4 is kept in a reduced pressure state. In addition, when returning the inside of the pot 4 from a reduced pressure state to the same pressure as the outside air, the operation of the pressure reducing pump 39 is stopped, and a path (not shown) connecting the pressure reducing pump 39 and the inside of the pot 4 is opened. In other words, the pressure reducing means 38 also serves as a pressure return means for returning the inside of the pot 4 from a reduced pressure state to the same pressure as the outside air.

[0021] In addition, a unitized heating circuit board assembly 42, including a heating control means 41, is arranged inside the main body 1. The heating control means 41 is configured to electrically control each part of the rice cooker and includes a control IC 43 that constitutes a microcomputer, a storage means 44 (see Figure 4) such as a memory that can read and write various information and data, and a timing means 45 (see Figure 4) such as a timer that can measure the time related to rice cooking. In particular, the heating control means 41 is configured to control the temperature of the bottom of the pot 4 mainly by controlling the heating coil 11 based on the temperature detected by the pot sensor 12, and to control the temperature of the inner lid 24 facing the rice being cooked mainly by controlling the lid heater 31 based on the temperature detected by the lid temperature sensor 32.

[0022] Figure 3 shows a cross-sectional view and a plan view of the inner frame 5 and heating coil 11 as seen from the bottom side. Referring to this figure, the heating coil 11 in this embodiment is composed of a side coil 11-1 as the first coil and a bottom coil 11-2 as the second coil. The side coil 11-1 and the bottom coil 11-2 are each provided on the outer surface of the inner frame 5, that is, the outer surface of the pot storage section 3, so as to face the pot 4. Specifically, when the pot 4 is placed in the pot storage section 3, the bottom coil 11-2 is positioned as a bottom heater facing the outer surface of the bottom of the pot 4, and the side coil 11-1 is positioned as a side-bottom heater outside and above the bottom coil 11-2, facing the outer surface of the lower side of the pot 4. In this embodiment, the heating coil 11 is composed of two heating coils, but the present invention is not limited thereto, and may be composed of many more heating coils. In that case as well, each heating coil is arranged concentrically facing the lower side of the pot 4 from the bottom, and multiple heating coils are arranged in a vertical direction. Furthermore, the side coil 11-1 and the bottom coil 11-2 may each be individually formed in a helical shape or in a concentric circular shape, and there are no particular restrictions on the shape of each heating coil.

[0023] To explain the heat transfer when the heating coil 11 is driven, when the side coil 11-1 is energized, the outer surface of the lower side of the pot 4, which is opposite the side coil 11-1, becomes hot first, and this heat is transferred via the main material 7 to the water in the cooked food that is in contact with the lower side. Heat transfer in the cooked food mainly occurs together with the movement of water, but where there is rice in the cooked food, the movement of water is restricted to only the narrow gaps between the rice grains of the cooked food S, and the movement of water and heat slows down. On the other hand, where there is no rice, the movement of water and heat becomes active due to convection, so after the water in the cooked food that is in contact with the lower side, the water in the upper part of the cooked food where there is no rice because it sinks downwards becomes hot. Subsequently, in the central part of the cooked food, the water and heat from the upper part of the cooked food, which has become hot, move to the middle part of the cooked food, which is a low temperature part, and then move to the lower part of the cooked food. This phenomenon is known as thermal convection, and in this embodiment, it will be described as external convection.

[0024] When the bottom coil 11-2 is energized, the outer surface of the bottom of the pot 4, which is opposite the bottom coil 11-2, becomes hot first, and this heat is transferred via the main material 7 to the water in the cooked food that is in contact with the bottom. In the lower part of the cooked food, the rice has settled downwards, so the upper part of the lower part is covered with the rice and water, and the temperature and pressure of this water rise. Subsequently, the water in the lower part, which has become hotter and more pressured, moves upward through the gaps between the rice grains, and is blown upward. As a result, the water in the lower part that has become hotter, i.e., the hot water, moves along with the heat to the middle part of the cooked food, and then to the upper part. This phenomenon is called blowing up, and in this embodiment, it is described as internal convection.

[0025] Therefore, by alternately energizing the side coil 11-1 and the bottom coil 11-2, alternating external and internal heat convection occurs in the food being cooked in the pot 4. This promotes stirring of the water in the food being cooked in the pot 4, thereby reducing uneven heating.

[0026] Figure 4 shows the electrical configuration of the rice cooker in this embodiment. In the figure, the heating control means 41 equipped on the main body 2 receives temperature detection signals from the pot sensor 12 and lid temperature sensor 32, a pressure detection signal from the pressure sensor 36, a detection signal from the lid opening / closing detection means 27, and a control signal from the display / operation control means 51, which will be described later. During cooking and warming, it sends control signals to the side coil driving means 46, the bottom coil driving means 47, and the lid heater driving means 48, respectively, to control the heating coil 11 that heats the pot 4 and the lid heater 31 that heats the inner lid 24, respectively. It also controls the solenoid 35 that moves the aforementioned pressure regulating valve 34 and the operation of the pressure reducing pump 39 of the pressure reducing means 38, respectively.

[0027] The side coil driving means 46 receives a heating control signal from the control means 41 and supplies a high-frequency current to energize the side coil 11-1, while the bottom coil driving means 47 receives a heating control signal from the control means 41 and supplies a high-frequency current to energize the bottom coil 11-2. These side coil driving means 46 and bottom coil driving means 47 are configured with, for example, a power supply circuit, an inverter, an IH drive circuit, and a switch element, and the output from the side coil 11-1 and bottom coil 11-2 to the pot 4 can be increased or decreased by changing the period of the high-frequency current supplied to the side coil 11-1 and bottom coil 11-2, and the ratio of the ON time to one period (ON ratio). The lid heater driving means 48 receives a heating control signal from the control means 41 and drives the lid heater 31 by supplying a DC current or AC current. In this embodiment, the current supply to the side coil 11-1 and the bottom coil 11-2 is described as being selectively switched by a switch element, but the present invention is not limited to this, and may include a period in which the side coil 11-1 and the bottom coil 11-2 are energized simultaneously.

[0028] The heating control means 41 includes a rice cooking control means 53 and a heat retention control means 54 on the control IC 43 as functions on the control sequence of the program read from the storage means 48. The rice cooking control means 53, upon receiving an instruction to start rice cooking from the operation means 19, sequentially executes the following steps to control the rice cooking process: a soaking cooking step to raise the temperature of the rice to be cooked in the pot 4 to a temperature of, for example, 35-55°C, and a maximum of 60°C, which is the temperature at which the rice does not gelatinize, in order to promote water absorption of the rice; a boiling heating step to raise the temperature of the rice to be cooked to a boil in a short time in order to gelatinize the rice; a boiling continuation step to maintain the boiling state of the rice to be cooked; and a steaming step to maintain a high temperature that does not burn the rice. The rice cooking control means 53 then sequentially executes the following steps to cook the rice inside the pot 4 at a desired pressure.

[0029] On the other hand, the display and operation control means 51 includes a control IC 56 that constitutes a microcomputer, a storage means 57, and a timing means (not shown), and receives operation signals from the operation means 19 and control signals from the heating control means 41 to control the display operation of the display means 18 and transmit control signals to the heating control means 41. This display and operation control means 51 is equipped with a display control means 58 and a condition setting means 59 on the control IC 56 as functions on the control sequence of the program stored in the storage means 57. The display control means 58 generates various control signals based on operation signals from the operation means 19 and controls the display operation of the display means 18. The condition setting means 59 works in conjunction with the display control means 58 to enable the selection and setting of conditions that can be selected by the operation means 19, such as selecting and setting a desired rice cooking course from among rice cooking courses that have multiple settings for rice, cooking method, hardness, and water hardness.

[0030] The memory means 44 stores, for example, rice cooking courses corresponding to the settings for each type of rice, cooking method, and firmness. The display control means 58 controls the display means 18 to display the rice settings, cooking method, and firmness settings of the rice cooking courses stored in the memory means 44 in a selectable format, and the user selects these settings using the operation means 19, thereby selecting and setting the rice cooking course. Furthermore, the memory means 44 stores multiple heating patterns, which are the driving patterns of the heating coil 11, lid heater 31, pressure regulating valve 34, and pressure reducing means 38, specifying the timing and output at which the heating coil 11, lid heater 31, pressure regulating valve 34, and pressure reducing means 38 are driven, as well as multiple energizing patterns, which are the energizing patterns of the side coil 11-1 and bottom coil 11-2, specifying the timing and output at which the side coil 11-1 and bottom coil 11-2 are energized when the heating coil 11 is driven. The rice cooking control means 53 and the warming control means 54 control the heating coil 11, lid heater 31, pressure regulating valve 34, and pressure reducing means 38 based on these heating patterns and energizing patterns.

[0031] The energizing pattern of this embodiment is a pattern that includes the energizing time and output of the side coil 11-1 and the bottom coil 11-2. For example, the side coil 11-1 is energized with output W1 and energizing time T1, then the coil is switched to energize the bottom coil 11-2 with output W2 and energizing time T2, and this is repeated for a predetermined period of time. The energizing pattern also includes cases where only the energizing time and output of the coil are varied, while the other remains constant. For example, this includes cases where the energizing time is constant among multiple coils but the output differs for each coil, or where the output is constant among multiple coils but the energizing time differs for each coil.

[0032] Here, "switching the energizing pattern" means switching the energizing pattern itself. To explain using the example above, it means switching from an energizing pattern that repeatedly energizes the side coil 11-1 with output W1 and energizing time T1, and then energizes the bottom coil 11-2 with output W2 and energizing time T2, to an energizing pattern that repeatedly energizes the side coil 11-1 with output W3 and energizing time T3, and then energizes the bottom coil 11-2 with output W4 and energizing time T4, at a predetermined timing.

[0033] The energizing pattern may include a switching time during which the energizing of all coils is turned OFF when the coils are switched. That is, the energizing pattern may consist of energizing one coil for a predetermined time and output → switching time 1 → energizing the other coil for a predetermined time and output → switching time 2, and repeating this as one cycle. Here, switching time 1 and switching time 2 may be the same time or they may be different times.

[0034] The energizing time and output of the side coil 11-1 and bottom coil 11-2 in each energizing pattern may be values ​​determined by the inventors of the present invention through diligent experimentation in each process. For example, the energizing time of the side coil 11-1 and bottom coil 11-2 is preferably several seconds or more, which allows for the alternating generation of external and internal heat convection in the cooked rice in the pot 4 for a predetermined period of time or longer, thereby promoting the stirring of the water in the cooked rice in the pot 4 and reducing uneven heating.

[0035] Furthermore, the inventors of this application have found that it is preferable that the time for generating external and internal convection is not the same in one energizing pattern. That is, it is preferable that the energizing times of the side coil 11-1 and the bottom coil 11-2 in one energizing pattern are not the same, and that the energizing times of the switched coils are different before and after the switching of the coils during repetition.

[0036] Furthermore, in the heat retention process, as will be described later, there is also a power supply pattern in which the energization of one coil is controlled while the other coil is not energized. In this power supply pattern, one coil is energized for a predetermined time and output, and then the same coil is not energized for a predetermined time, and this process is repeated.

[0037] Figure 5 shows a top view of the LCD 16, and in each drawing, the top side is referred to as "front," the bottom side as "rear," the left side as "left," and the right side as "right." Also, in each drawing, the front side is referred to as "top" and the back side as "bottom." Figure 5 shows the top screen G1. When the user plugs the power plug, which is pre-installed on the main unit 1, into a household outlet, the necessary power is supplied to each part of the rice cooker. At this time, the display control means 58 causes the LCD 16 to display the arrangement of the top screen G1 shown in Figure 5 as the initial screen for normal use, after a predetermined time has elapsed or when displaying a predetermined startup display screen.

[0038] Referring to Figure 5, the top screen G1 is described as having a menu key display area A1 at its front, with four button display areas B1 to B7 arranged side by side. Here, the "Rice" button display area B1 includes the text display element D1 that says "Rice" and the text display element D2 that says "▼". The "Cooking Method" button display area B3 includes the text display element D3 that says "Cooking Method" and the text display element D4 that says "▼". The "Hardness Adjustment" button display area B5 includes the text display element D5 that says "Hardness Adjustment" and the text display element D6 that says "▼". The "Water Hardness" button display area B7 includes the text display element D7 that says "Water Hardness" and the text display element D8 that says "▼".

[0039] Furthermore, behind the menu key display area A1, a rice cooking information display area A2 is formed, with four setting display units D11 to D14 arranged side by side. Here, the "Rice" setting display unit D11 displays information about the selected rice and is located behind the "Rice" button display unit B1, showing "White Rice, Brand Selection" in Figure 4. The "Cooking Method" setting display unit D12 displays information about the selected cooking method and is located behind the "Cooking Method" button display unit B3, showing "Kamado Master" in Figure 4. The "Hardness Adjustment" setting display unit D13 displays information about the selected hardness adjustment and is located behind the "Hardness Adjustment" button display unit B5, showing "Recommended" in Figure 4. The "Water Hardness" setting display unit D14 displays information about the selected water hardness and is located behind the "Water Hardness" button display unit B7, showing "40-60" in Figure 4.

[0040] Behind the rice cooking information display area A2, there is a text display unit D15 that says "Rice Cooking Time," which suggests that the numbers displayed on the clock display unit D16 are the rice cooking time. In Figure 5, the clock display unit D16 shows "approximately 38 minutes," which is the rice cooking time calculated from the settings in the rice cooking information display area A2, and the button display unit B17, which includes a text display unit D17 that says "Start Rice Cooking," are displayed side by side.

[0041] Also, at the rear of the top screen G1, a setting button display section B18 containing a text display element D18 reminiscent of a gear diagram, a button display section B19 containing a text display element D19 labeled "Keep Warm", a button display section B20 containing a text display element D20 labeled "Reservation", a time display element D21 displaying the current time, and a button display section B22 containing a text display element D22 labeled "Off" are displayed side by side.

[0042] The "Off" button display unit B22 is operated when stopping rice cooking or keeping warm. When the "Off" button display unit B22 is touched, the display control unit 58 receives an operation signal from the operation unit 19 located above the "Off" button display unit B22 and transmits it to the heating control unit 41. The rice cooking control unit 53 then controls the unit to stop heating the food in the pot 4 and the scheduled cooking, and to set it to the "Off" state. The display control unit 58 then controls the display unit 18 to display the top screen G1 with the setting of the rice cooking information display area A2 set to the setting from the most recent cooking, that is, the setting stored in the memory unit 57. Furthermore, when the "Off" button display area B22 is touched on the top screen G1, the display control means 58 controls the display means 18 to discard the rice settings, cooking method settings, hardness adjustment settings, and water hardness settings that were set before cooking and are currently displayed in the cooking information display area A2, and to display the cooking information display area A2 with the settings from the most recent cooking, that is, the settings stored in the storage means 57.

[0043] The "Start Cooking" button display unit B17 is operated when cooking rice. When the "Start Cooking" button display unit B17 is touched, the condition setting means 59 stores the rice settings, cooking method settings, hardness settings, and water hardness settings currently displayed in the cooking information display area A2 in the storage means 57 as the settings for the current cooking course. The cooking control means 53 then controls the start of cooking for the food to be cooked in the main unit 1 using the settings for the current cooking course stored in the storage means 44.

[0044] The "Keep Warm" button display unit B19 is operated when the "Keep Warm" function is activated. When the "Keep Warm" button display unit B19 is touched, the keep-warm control means 54 sends appropriate control signals to the heating coil 11 and lid heater 31 to start reheating the food being cooked inside the main unit 1.

[0045] The "Rice" button display unit B1 is operated to select the type and brand of rice to be cooked. When the "Rice" button display unit B1 is touched, the display control means 58 controls the display means 18 to display a rice selection screen (not shown). When a type and brand of rice is selected on this rice selection screen, the display control means 58 returns to the top screen G1 and controls the display means 18 to display the selected type and brand of rice in the text display unit D11.

[0046] The "Cooking Method" button display section B3 is operated to select the type of cooking method for the food to be cooked. When the "Cooking Method" button display section B3 is touched, the display control means 58 controls the display means 18 to display a cooking method selection screen (not shown). When a cooking method for the food to be cooked is selected on this cooking method selection screen, the display control means 58 returns to the top screen G1 and controls the display means 18 to display the selected cooking method for the food to be cooked in the text display unit D12.

[0047] The "hardness adjustment" button display section B5 is operated to select the type of texture of the rice to be cooked. When the "hardness adjustment" button display section B5 is touched, the display control means 58 controls the display means 18 to display a hardness selection screen (not shown). When a rice texture is selected on this cooking method selection screen, the display control means 58 returns to the top screen G1 and controls the display means 18 to display the selected rice texture in the text display unit D13.

[0048] The "Water Hardness" button display unit B7 is operated to select the water hardness for cooking rice. When the "Water Hardness" button display unit B7 is touched, the display control means 58 controls the display means 18 to display a water hardness selection screen (not shown). When a water hardness is selected on this water hardness selection screen, the display control means 58 returns to the top screen G1 and controls the display means 18 to display the selected water hardness in the text display unit D14.

[0049] The setting button display unit B18 is operated to set the rice cooker. When the setting button display unit B18 is touched, the display control means 58 controls the display means 18 to display a setting screen (not shown).

[0050] The "Reservation" button display unit B20 is operated when performing a reservation cooking function. When the "Reservation" button display unit B20 is touched, the display control unit 58 controls the display unit 18 to display a reservation setting screen (not shown). Once the reservation is set on this reservation setting screen and the reservation cooking is started, the cooking control unit 53 starts cooking so that the food to be cooked in the main unit 1 is cooked by the set reservation time, and the warming control unit 54 also starts keeping the food warm.

[0051] Next, the operation of the rice cooker with the above configuration during the rice cooking process will be explained. Figure 6 shows the changes over time of the pot temperature t, which is the temperature detected by the pot temperature sensor 12, the output Po of the side coil 11-1 and the bottom coil 11-2, and the pressure Pr inside the pot 5, which is the pressure detected by the pressure sensor 36, during the rice cooking process of the rice cooker of this embodiment.

[0052] Referring to Figure 6, the operation of this embodiment during rice cooking is as follows: First, rice and water (as liquid) are placed in the pot 4, and after setting the pot 4 in the pot storage section 3, the lid 2 is closed. Around the same time, when the rice cooker is powered on, the main body 1 and lid 2 enter an initial off (standby) state where cooking and warming are not taking place.

[0053] Then, when the user touches the "Start Cooking" button display area B17 on the top screen G1 after setting the cooking course using the operation means 19, the condition setting means 50 stores the rice settings, cooking method settings, hardness settings, and water hardness settings currently displayed in the cooking information display area A2 as the settings for the current cooking course in the storage means 57, and transmits these cooking course settings from the display / operation control means 51 to the heating control means 41. The cooking control means 51 of the heating control means 41 then performs the soaking, boiling, boiling, and steaming processes for the food to be cooked in the pot 4 according to the heating pattern of the current cooking course settings stored in the storage means 44.

[0054] When the soaking process begins, the rice cooking control means 53 controls the operation of the pressure regulating unit 26 and the pressure reducing means 38 respectively so that the pressure inside the pot 4 becomes a reduced pressure state lower than atmospheric pressure, and the process transitions to a no-heat soaking process. Specifically, when the no-heat soaking process begins, the rice cooking control means 53 controls the solenoid 35 to close the steam discharge path 33 with the pressure regulating valve 34. In this state, based on the pressure detection by the pressure sensor 36, the rice cooking control means 53 opens the path of the pressure reducing means 38 and operates the vacuum pump 39 continuously to perform vacuuming, removing the air from inside the sealed pot 4 with the vacuum pump 39. The display control means 53 also controls the LED display unit 17 to light up the "vacuum" process LED display unit. Subsequently, the rice cooking control means 53 controls the pressure reducing means 38 so that the pressure inside the pot 4 is maintained below a certain value in a reduced pressure state lower than atmospheric pressure. In this way, the inside of the pot 4 is kept in a reduced pressure state.

[0055] In this embodiment, the time T of the non-heated soaking process is A This setting changes depending on the rice settings, hardness settings, and cooking method settings, but it does not change depending on the amount of food being cooked or the water hardness settings, and is configured to reach a predetermined value. Therefore, for a predetermined time T AThe rice can be cooked in a reduced-pressure environment with room-temperature water inside pot 4, allowing the rice to absorb water thoroughly regardless of the amount of food being cooked or the water hardness setting. As mentioned above, rice tends to release starch more easily when its temperature is rapidly increased. By cooking the rice with room-temperature water, cracking of the rice surface is suppressed even when the temperature of the food being cooked rises, preventing the rice from becoming mushy and improving the gloss and texture of the cooked rice. In addition, by releasing the air inside pot 4 to the outside, the amount of air dissolved in the water of the food being cooked is reduced.

[0056] The rice cooking control means 53 receives time T from the timing means 45 after the start of the non-heated soaking process. A Upon receiving the elapsed time signal, the process proceeds to the heating and soaking stage.

[0057] When the heating and soaking process begins, the rice cooking control means 53 controls the solenoid 35 to rotate the pressure regulating valve 34 to open the steam discharge path 33, thereby connecting the inside of the pot 4 to the outside of the main unit 1, and releasing steam from the rice being cooked through the steam discharge path 33 to the outside of the main unit 1 through the steam outlet 15. By fluctuating the pressure inside the pot 4 in this way, air that was inside the rice being cooked is expelled from the rice, and water is allowed to permeate in place of the expelled air, so that water can be absorbed into the inside of the rice.

[0058] Furthermore, when the heating and soaking process begins, the rice cooking control means 53 outputs a heating control signal to the side coil driving means 46, controlling the side coil 11-1 to heat the pot 4 at a predetermined output for a predetermined time T1. After time T1 has elapsed, the rice cooking control means 53 controls the side coil 11-1 to stop heating the pot 4 for a predetermined time T2, and performs a capacity determination process to determine the cooking capacity, which is the amount of rice to be cooked, based on the pot temperature t1 after time T2 has elapsed. The predetermined time T2 is set to a time that allows for a temperature drop sufficient to enable capacity determination from the time T1 when heating stops. In this embodiment, in the capacity determination process, the bottom coil 11-2, which is the heating coil 11 closest to the pot sensor 12, is not used, and only the side coil 11-1, which is the heating coil 11 furthest from the pot sensor 12, is used to heat the pot 4. Therefore, the pot sensor 12 is suppressed from being affected by the heating of the heating coils 11, and the deterioration of the temperature detection accuracy of the pot sensor 12 can be suppressed.

[0059] In this embodiment, the rice cooking control means 53 is configured to control the side coil 11-1 to heat the pot 4 for a predetermined time T1 at a predetermined output when it receives a detection signal from the pressure sensor 36 indicating that the pressure inside the pot 4 has returned to atmospheric pressure. However, this is just one example, and it is sufficient that the start of heating the pot 4 and at least the period of the steam discharge path 33 overlap. For example, the pot 4 may be heated first and then allowed to return to atmospheric pressure. The order of starting the heating of the pot 4 and opening the steam discharge path 33 does not matter, and they may be performed simultaneously. In this embodiment, the steam discharge path 33 is opened during the heating and soaking process, but it may also be configured to open the steam discharge path 33 during the non-heating and soaking process, particularly towards the end of the non-heating and soaking process, to return the pressure inside the pot 4 to atmospheric pressure.

[0060] Furthermore, the rice cooking control means 53 receives a detection signal from the pressure sensor 36 indicating that the pressure inside the pot 4 has returned to atmospheric pressure, and then receives a timing signal indicating that a predetermined time, such as 10 seconds, has elapsed. Upon receiving this signal, it controls the solenoid 35 to close the steam discharge path 33 with the pressure regulating valve 34. Based on the pressure detection by the pressure sensor 36, it opens the path of the depressurization means 38 and operates the vacuum pump 39 continuously to perform vacuuming. Subsequently, the rice cooking control means 53 controls the depressurization means 38 so that the pressure inside the pot 4 is maintained below a certain value in a depressurized state lower than atmospheric pressure. In this way, the inside of the pot 4 is kept in a depressurized state throughout the heating and soaking process. Since more air is dissolved in water at higher water temperatures, performing vacuuming while the pot 4 is heated allows more air inside the pot 4 to be released outside the machine, thereby reducing the amount of air dissolved in the water of the rice being cooked. By reducing the amount of air in the water and degassing it in this way, the number of bubbles generated when the water boils is reduced, and the diameter of the bubbles becomes smaller. This improves the heat conductivity of the water, suppresses the breakdown of rice grains during cooking, prevents the rice from becoming mushy, and improves the gloss and texture of the cooked rice. If the steam discharge path 33 is opened during the non-heated soaking process to return the pressure inside the pot 4 to atmospheric pressure, the steam discharge path 33 may be closed by the pressure regulating valve 34 when a timing signal is received indicating that a predetermined amount of time has elapsed since the start of the heated soaking process, and vacuuming may be performed based on the pressure detected by the pressure sensor 36.

[0061] In this embodiment, the heating time T1 for the pot 4 in the capacity determination step is set to 30 seconds or more, and this "30 seconds" is the time required to determine between the minimum capacity and other capacities, which is the minimum distinction for capacity determination. Also, the time T2 for stopping heating the pot 4 in the capacity determination step is set to 1 minute or more, and this "1 minute" is the time required to determine between the minimum capacity and other capacities. Therefore, for example, in a rice cooking course that prioritizes time, such as the "quick cook" course, time T1 may be set to 30 seconds and time T2 to 1 minute.

[0062] Also, in this embodiment, when the rice cooking control means 53 receives a detection signal from the pan sensor indicating that the pan temperature t1 has reached 60°C during the time T1 for heating the pan 4, the rice cooking control means 53 stops heating the pan 4 at the moment it receives the detection signal, and then controls the side coil 11-1 to stop heating the pan 4 for a predetermined time T2. When the rice and water, which are the objects to be cooked, reach 60°C or higher, the gelatinization of the rice during water absorption may be promoted, which may deteriorate the cooking of the rice. Therefore, in the capacity determination step, the pan temperature t1 is kept below 60°C to suppress the gelatinization of the rice during water absorption.

[0063] FIG. 7 graphically shows the change over time of the pan temperature of a conventional rice cooker and the change over time of the pan temperature of the rice cooker of this embodiment in the capacity determination step of the simmering process, for different amounts of the object to be cooked. Here, the t indicated by the solid line 0O 、t 0B 、t 0M 、t 0S are graphs of the detection temperature of the pan sensor 12 when the amount of the object to be cooked in the conventional rice cooker is extra-large, large, medium, and small, and the t indicated by the dotted line 1O 、t 1B 、t 1M 、t 1S 、is a graph of the pan temperature t1, which is the detection temperature of the pan sensor 12 when the amount of the object to be cooked in the rice cooker of this embodiment is extra-large, large, medium, and small. Conventionally, both the side coil 11-1 and the bottom coil 11-2 are used to heat the pan 4, and especially when the capacity is small, t 0S rises up to near 60°C, and the temperature of the bottom of the pan 4 may rise too much, and the gelatinization of the rice may progress. Therefore, in this embodiment, only the side coil 11-1 is used, and the output of the entire heating coil 11 is suppressed compared to the conventional rice cooker to heat the pan 4 and suppress the rise in the temperature of the bottom of the pan 4.

[0064] In this embodiment, the rice cooking control means 53 determines the cooking capacity based on the pot temperature t1 at the end of time T2. The capacity determination based on the pot temperature t1 at the end of time T2 may be based solely on the pot temperature t1 at the end of time T2, on the difference between the pot temperature t1 at the end of time T2 and the pot temperature at the start of the soaking and cooking process, or on the difference between the pot temperature t1 at the end of time T2 and the pot temperature t1 at time T1 when heating stopped. Furthermore, the pot temperature t1 at the start of the soaking and cooking process may be set to a predetermined fixed value.

[0065] In this embodiment, the cooking capacity is determined solely by the pot temperature t1 at the end of time T2. Here, the cooking capacity can be determined, for example, by setting threshold ranges for the amount of rice to be cooked (extra large, large, medium, and small) relative to the pot temperature at the end of time T2, and determining which range the pot temperature at the end of time T2 falls into. As shown in Figure 6, at the end of time T2, the t of this embodiment 1O t 1B t 1M , and t 1S The temperature difference between them is different from conventional t 0O t 0B t 0M , and t 0S It can be seen that the temperature difference is greater than that between the two. In other words, the rice cooker of this embodiment can improve grouping accuracy and determine the cooking capacity more precisely due to the larger temperature difference. However, the present invention is not limited to this, and the method for determining the cooking capacity is just one example.

[0066] When the rice cooking control means 53 receives a timing signal from the timing means 45 indicating that time T2 has elapsed, it outputs heating control signals to the side coil driving means 46 and the bottom coil driving means 47, respectively, based on the temperature detection of the bottom of the pot 4 by the pot temperature sensor 12, and controls the side coil 11-1 and the bottom coil 11-2 to alternately energize, thereby heating the pot 4 and raising the water temperature inside the pot 4 to a predetermined temperature, for example, 35 to 55°C, and a maximum of 60°C, as shown in Figure 5, to promote water absorption by the rice.

[0067] Specifically, the rice cooking control means 53 controls the side coil 11-1 and the bottom coil 11-2 to alternately energize them, with the duty cycle of the bottom coil 11-2 being A% and the duty cycle of the side coil 11-1 being B%. Furthermore, throughout the entire rice cooking process, when there is a switch between energizing the side coil 11-1 and the bottom coil 11-2, the rice cooking control means 53 controls the system to include a switching time in which both the side coil 11-1 and the bottom coil 11-2 are turned OFF during the switching. The length of this switching time may be constant or may be changed according to the rice cooking process. Alternatively, the control may not include a switching time.

[0068] As the hardness of the water to be cooked increases and the amount of impurities in the water increases, the water absorption rate of the rice deteriorates due to the difference in osmotic pressure. Furthermore, calcium and other substances in the water act as barriers that block the tiny pores of the rice, inhibiting water absorption. This prevents water from penetrating deep into the rice, and even when cooking with the same quality and quantity of rice, the same amount of water, and the same cooking course settings, there is a risk of producing hard, dry, and undercooked rice that is not gelatinized to the core. Therefore, in this embodiment, the internal pressure of the pot 4 is adjusted by changing the energizing time and duty cycle of the vacuum pump 39 according to the water hardness selected when setting the cooking course, and / or the time the pot 4 is depressurized by changing the soaking cooking process time. The harder the water to be cooked, the more the pot 4 is depressurized and / or the soaking cooking process time T is changed. B The depressurization means 38 is operated to extend the pressure. By reducing the pressure inside the pot 4 to a level corresponding to the hardness of the water being cooked, the rice is able to absorb water, and even if the water hardness is high, the cooked rice is gelatinized to the core, resulting in tastier rice cooked according to the water.

[0069] Subsequently, the rice cooking control means 53 receives time T from the timing means 45 from the start of the heating and soaking process. B Upon receiving the elapsed time signal, the soaking and cooking process ends and the process moves on to the next boiling and heating step.

[0070] When shifting to the boiling heating step, the rice cooking control means 53 outputs heating control signals to the side coil driving means 46 and the bottom coil driving means 47 respectively, and controls to alternately energize the side coil 11-1 and the bottom coil 11-2 so as to heat the rice to be cooked in the pot 4 more strongly than in the simmering step, and heats until the boiling of the rice to be cooked is detected.

[0071] Specifically, when shifting to the boiling heating step, at the beginning of the boiling heating step, the rice cooking control means 53 slightly increases the duty ratio C% of the bottom coil 11-2 compared to the duty ratio A% in the simmering step (C > A), and makes the duty ratio of the side coil 11-1 and the duty ratio of the bottom coil 11-2 substantially the same, and controls with an energization pattern that alternately energizes the side coil 11-1 and the bottom coil 11-2 with an output slightly stronger than in the simmering step. Here, the rice cooking control means 53 changes the energization time of the side coil 11-1 and the bottom coil 11-2 according to the amount of the rice to be cooked determined in the capacity determination step in the boiling heating step. For example, if the duty ratio of the bottom coil 11-2 is D% when the amount of the cooked rice is extremely large, E% when the amount of the cooked rice is large, F% when the amount of the cooked rice is medium, and G% when the amount of the cooked rice is small, the duty ratio is set to be larger in the order of D < E < F < G, and the duty ratio of the side coil 11-1 is set to D > E > F > G.

[0072] Here, the rice cooking control means 53 stops the operation of the pressure reducing pump 39 of the pressure reducing means 38 and controls the path of the pressure reducing means 28 to be closed so that the inside of the pot 4 remains in a reduced pressure state lower than atmospheric pressure, continuing from the soaking and cooking process. Therefore, even after transitioning from the soaking and cooking process to the boiling and heating process, although the pressure inside the pot 4 gradually increases due to heating and slow leaks, the reduced pressure state can be maintained for a while without operating the pressure reducing pump 39. In this way, the contents being cooked inside the pot 4 are kept in a reduced pressure state even during the boiling and heating process after the soaking and cooking process, so that the water boils at a temperature of 100°C or less during the boiling and heating process. Therefore, by boiling the contents being cooked in a reduced pressure state at 60°C to 100°C, which is considered the gelatinization temperature of rice, the bubbles during boiling cause the rice to swirl, eliminating uneven heating, and at the same time, keeping the contents being cooked in a reduced pressure state allows the rice to absorb water to the core in a short time.

[0073] Subsequently, when the rice cooking control means 53 receives a timing signal from the timing means 45 indicating that a predetermined time has elapsed since the start of the boiling heating process, it energizes the bottom coil 11-2 for J seconds and the side coil 11-1 for K seconds in one cycle, which is the same as or different from the energizing time of the bottom coil 11-2 for H seconds and the energizing time of the side coil 11-1 for I seconds in one cycle at the beginning of the heating process. The control means 53 then controls the heating for a predetermined time in an energizing pattern of energizing the bottom coil 11-2 → switching time → energizing the side coil 11-1 → switching time, with the side coil 11-1 and bottom coil 11-2 being energized alternately at the same or lower output as at the beginning of the heating process. Furthermore, during the subsequent boiling heating process, boiling continuation process, and steaming process, the rice cooking control means 53 controls the heating coil 11 with an energizing pattern that alternately energizes the side coil 11-1 and the bottom coil 11-2 in the pattern of energizing the bottom coil 11-2 → switching time → energizing the side coil 11-1 → switching time.

[0074] Furthermore, the energizing time of the bottom coil 11-2 may be set to increase in the order of extra-large ≤ large ≤ medium ≤ small for the amount of rice being cooked, while the energizing time of the side coil 11-1 may be set to increase in the order of small ≤ medium ≤ large ≤ extra-large for the amount of rice being cooked. In addition, the period of the energizing pattern, which is the energizing pattern of the side coil 11-1 and the bottom coil 11-2 when the heating coil 11 is driven, may be set to increase in the order of small ≤ medium ≤ large ≤ extra-large.

[0075] The rice cooking control means 53 receives a temperature detection signal from the pot temperature sensor 14, and when the detected temperature at the bottom of the pot 4 reaches a predetermined temperature, such as 70°C, it controls the solenoid 35 to rotate the pressure regulating valve 34 to open the steam discharge path 33, without operating the pressure reducing pump 39, thereby connecting the inside of the pot 4 to the outside of the main unit 1, and releasing steam from the food being cooked through the steam discharge path 33 to the outside of the main unit 1 through the steam vent 15. The display control means 53 then controls the LED display unit 17 to turn off the "vacuum" process LED display unit.

[0076] Then, when the rice cooking control means 53 receives a timing signal from the timing means 45 indicating that a predetermined time has elapsed, it controls the power supply pattern by maintaining a predetermined output (H+I≧J+K≧L+M) while making the total power supply time L+M seconds, which is the sum of the power supply time L seconds for the bottom coil 11-2 and the power supply time M seconds for the side coil 11-1 in one cycle, the same as or less than the total power supply time J+K seconds, which is the sum of the power supply time J seconds for the bottom coil 11-2 and the power supply time K seconds for the side coil 11-1 in one cycle, thereby alternately powering the side coil 11-1 and the bottom coil 11-2. Here, the power supply time for the bottom coil 11-2 may be set to be longer in the order of extra-large ≤ large ≤ medium ≤ small, as before, while the power supply time for the side coil 11-1 may be set to be longer in the order of small ≤ medium ≤ large ≤ extra-large.

[0077] Subsequently, when the rice cooking control means 53 receives a temperature detection signal from the pot sensor 12 indicating that the pot temperature t has reached a predetermined temperature or higher, for example, 90°C or higher, and / or receives a temperature detection signal from the lid temperature sensor 32 indicating that the lid temperature has reached a predetermined temperature or higher, for example, 90°C or higher, it starts boiling detection to detect when the rice being cooked is boiling.

[0078] When boiling detection is initiated, the rice cooking control means 53 controls the solenoid 35 to rotate the pressure regulating valve 34 to close the steam discharge path 33, thereby sealing the inside of the pot 4. As described above, the food to be cooked is strongly heated inside the pot 4, so the food to be cooked is pressurized inside the pot 4 until it reaches above atmospheric pressure, for example, 1.2 atmospheres, and the water in the food to be cooked can be boiled under this pressurized state. This ensures a balance between the hardness and stickiness of the rice by boiling the water in the food to be cooked at 105°C (at 1.2 atmospheres), which is the optimal gelatinization temperature for rice under pressurized conditions. The display control means 53 also controls the LED display unit 17 to light up the "pressure" process LED display unit. The rice cooking control means 53 may also control the solenoid 35 to adjust the pressure inside the pot 4 based on the pressure detected by the pressure sensor 36, for example, depending on the setting of the type of rice.

[0079] Also, the rice cooking control means 53 makes the total energization time N + O seconds of the bottom coil 11-2 and the energization time O seconds of the side coil 11-1 in one cycle approximately equal to the total energization time L + M seconds in one cycle of the previous heating step. On the other hand, the energization time N seconds of the bottom coil 11-2 is made slightly shorter than the energization time L seconds of the bottom coil 11-2 in the previous heating step (N < L), and the energization time O seconds of the side coil 11-1 is made slightly longer than the energization time M seconds of the side coil 11-1 in the previous heating step (O > M), and it is controlled in an energization pattern where the side coil 11-1 and the bottom coil 11-2 are energized alternately. Therefore, the rice cooking control means 53 controls the bottom coil 11-2 and the side coil 11-1 in a plurality of different energization patterns in the boiling heating step. On the other hand, the rice cooking control means 53 controls the bottom coil 11-2 and the side coil 11-1 in different energization patterns according to the amount of the object to be cooked, similar to the above-described control in the boiling heating step.

[0080] Also, the rice cooking control means 53 calculates the inclination of the detected temperature, that is, how much the detected temperature of the pot sensor 12 and the detected temperature of the lid temperature sensor 32 rise in a predetermined time. Specifically, when the rice cooking control means 53 calculates that the rise in the pot temperature t, which is the temperature at the bottom of the pot 4, from the detected temperature of the pot sensor 12, becomes, for example, 3°C or less in 120 seconds, that is, below a predetermined temperature rise rate, it determines that boiling has been detected due to the change in the temperature rise rate of the pot temperature t. Also, when the rice cooking control means 53 calculates that the rise in the lid temperature, which is the temperature of the inner lid 24, from the detected temperature of the lid temperature sensor 32, becomes, for example, 1°C or less in 60 seconds, that is, below a predetermined temperature rise rate, it determines that boiling has been detected due to the change in the temperature rise rate of the lid temperature. And when the rice cooking control means 53 detects boiling due to the change in the temperature rise rate of the pot temperature t and also detects boiling due to the change in the temperature rise rate of the lid temperature, it proceeds to the next boiling continuation step. Incidentally, the predetermined temperature rise rates of the pot temperature t1 and the lid temperature t2 for detecting these boilings may be adjusted and set respectively according to the amount of the object to be cooked determined in the capacity determination step. Also, the method of detecting boiling is an example, and it may be configured to proceed to the next boiling continuation step when the rice cooking control means 53 determines that boiling has been detected due to the change in the temperature rise rate of the pot temperature t.

[0081] When the process transitions to the boiling continuation stage, the rice cooking control means 53 controls the power supply to the heating coil 11 by switching it off until the pot temperature t reaches a predetermined temperature, based on the temperature detection signal from the pot sensor 12. At the same time, it controls the lid heater 33 to continuously supply power to maintain the lid temperature t2 at a predetermined temperature, such as 98°C or higher, based on the temperature detected by the lid temperature sensor 32. In the boiling continuation stage, the power supply pattern of the side coils 11-1 and bottom coils 11-2 when the heating coil 11 is driven is set so that the length of one cycle is longer than that of the boiling detection stage, i.e., the time during which the heating coil 11 is stopped, i.e., the OFF time of the heating coil 11.

[0082] Furthermore, once the boiling process has begun, the rice cooking control means 53 periodically controls the power supply of the solenoid 35 to repeatedly change the pressure inside the pot 4 between normal pressure and a pressure higher than atmospheric pressure, thereby periodically opening and closing the steam discharge path 33 with the pressure regulating valve 34.

[0083] The rice cooking control means 53 starts detecting when the rice is cooked when the water inside the pot 4 begins to disappear during the boiling process, and the temperature t at the bottom of the pot 4 reaches a predetermined temperature or higher based on the temperature detected by the pot temperature sensor 15, or when the temperature rise exceeds a predetermined rate of increase, such as 0.5°C or more in 10 seconds.

[0084] When the detection of the end of cooking is initiated, the rice cooking control means 53 controls the solenoid 35 to close the steam discharge path 33 with the pressure regulating valve 34. The rice cooking control means 53 also increases the energizing time Q seconds of the bottom coil 11-2 in one cycle from the energizing time O seconds of the bottom coil 11-2 in one cycle before the detection of the end of cooking in the boiling continuation process (Q>O), while setting the energizing time R seconds of the side coil 11-1 in one cycle to be less than or equal to the energizing time P seconds of the side coil 11-1 in one cycle before the detection of the end of cooking in the boiling continuation process (R≦P), and controls the side coil 11-1 and the bottom coil 11-2 with an energizing pattern that alternates between them. Therefore, in the end of cooking, the energizing time Q seconds of the bottom coil 11-2 in one cycle is set to be longer than the energizing time R seconds of the side coil 11-1. When the cooking is complete, there is almost no water left in the pot 4, and no internal or external convection occurs. Therefore, by making the energizing time of the bottom coil 11-2 longer than that of the side coil 11-1, the water remaining at the bottom of the pot 4 can be heated more efficiently from the bottom side. Here, the energizing time of the bottom coil 11-2 may be set to be longer in the order of extra-large ≥ large ≥ medium ≥ small in the amount of rice being cooked, as before. On the other hand, the energizing time of the side coil 11-1 may also be set to be longer in the order of extra-large ≥ large ≥ medium ≥ small in the amount of rice being cooked.

[0085] The rice cooking control means 53 receives a temperature detection signal from the pot sensor 12 indicating that the pot temperature t has reached a predetermined dry-up temperature, for example, 120°C, or calculates from the temperature detection signal from the pot sensor 12 that the rise in the pot temperature t has exceeded a predetermined temperature rise rate, for example, 0.5°C or more in 10 seconds. Upon this, it determines that the water inside the pot 4 has evaporated and the rice to be cooked has been detected, and proceeds to the next steaming step.

[0086] During the steaming process, the rice cooking control means 53 controls the lid heater 33 to maintain a predetermined lid temperature based on the temperature detected by the lid temperature sensor 32, thereby preventing condensation on the inner lid 24. It also controls the heating coil 11 to maintain a high temperature inside the pot 4, preventing the rice from burning, by continuously switching the power on and off for a predetermined time, thereby managing the temperature at the bottom of the pot 4. During this steaming process, the heating coil 11 is driven and stopped to some extent, so the rice cooking control means 53 controls it with a power supply pattern that is approximately the same as the power supply pattern for the cooking process, which has a shorter cycle length. The rice cooking control means 53 also controls the solenoid 35 to rotate the pressure regulating valve 34 to open the steam discharge path 33, connecting the inside of the pot 4 to the outside of the main unit 1, and releasing steam from the food being cooked through the steam discharge path 33 to the outside of the main unit 1 through the steam outlet 15. Furthermore, the display control means 53 controls the LED display unit 17 to turn off the "pressure" process LED display unit.

[0087] In this embodiment, the power to the heating coil 11 is controlled by changing the output and steaming process time according to the firmness setting selected when setting the rice cooking course. For example, the rice cooking control means 53 controls the power to the heating coil 11 to increase the amount of heating and shorten the steaming process time as the selected firmness setting becomes "firmer". On the other hand, the rice cooking control means 53 controls the power to the heating coil 11 to decrease the amount of heating and lengthen the steaming process time as the selected firmness setting becomes "softer".

[0088] Furthermore, when the rice cooking control means 53 receives a temperature detection signal from the pot sensor 12 indicating that the pot temperature t has dropped to a predetermined temperature, for example, 100°C, it controls the heating amount of the heating coil 11 to increase for a short time, and after that short time has elapsed, it controls the heating coil 11 to return to the heating amount before the increase in the steaming process, thereby removing excess moisture from the cooked rice and improving its taste.

[0089] When the rice cooking control means 53 receives a timing signal from the timing means 45 after a predetermined time has elapsed, the steaming process ends and the rice cooking process is completed, and the process moves to the warming process controlled by the warming control means 54.

[0090] Here, the inventors of the present invention conducted a comparative experiment using (A) tap water and (B) tap water from which the gas was removed using a pressure reducing device 38.

[0091] The pot 4 was heated simultaneously under the same conditions using the heating coil 11 with (A) tap water and (B) deaerated water as the contents to be cooked. Both were heated until boiling, and each pot 4 was photographed with the infrared camera of a thermographic device. Figure 8 shows the images taken. As shown in Figure 8, the temperature of the water in the center of the pot 4 rose higher with (B) deaerated water than with (A) tap water, indicating that it has higher thermal conductivity. Therefore, with (B) deaerated water, the rice is less likely to break down during cooking, the gloss and texture of the cooked rice are improved, and the superiority of the rice cooker of this embodiment was confirmed.

[0092] As described above, the rice cooker of this embodiment is equipped with a heating coil 11 as a heating means for heating a pot 4 that contains rice and water as the food to be cooked, and a depressurization means 38 for reducing the pressure inside the pot 4. In the soaking cooking process, in which the temperature of the food to be cooked placed in the pot 4 is raised to a temperature at which the rice does not gelatinize in order to promote water absorption of the rice, the depressurization operation is performed by reducing the pressure inside the pot 4 using the depressurization means 38. The configuration is such that the first soaking process is a non-heating soaking process in which the heating coil 11 is not driven, and the second soaking process is a heated soaking process in which the heating coil 11 is started to drive from a state where the inside of the pot 4 is at atmospheric pressure and the pot 4 is heated, and the depressurization operation is performed by the depressurization means 38.

[0093] By configuring it in this way, the time T of the non-heated soaking process is reduced. AThis method allows rice to absorb water in a reduced-pressure environment with room-temperature water inside pot 4, enabling water absorption to the inside of the rice grains regardless of the amount of rice being cooked or the water hardness setting. Furthermore, by performing vacuum evacuation while pot 4 is heated, in combination with the vacuum evacuation performed without heating in the first soaking process, more air can be released from inside pot 4 to the outside of the machine, reducing the amount of air dissolved in the water being cooked. This improves the heat conductivity of the water, thereby enhancing the gloss and texture of the cooked rice. Thus, it is possible to achieve both enhanced water absorption and good gloss and texture in the cooked rice.

[0094] Furthermore, in this rice cooker, the internal pressure of the pot 4 is set to atmospheric pressure at the start of the heating and soaking process, and by fluctuating the pressure inside the pot 4, water can be absorbed all the way to the inside of the rice grains.

[0095] Furthermore, in the rice cooker of this embodiment, the volume of the food to be cooked is determined based on the temperature change of the pot 4 during the second soaking process. This allows for automatic cooking according to the volume of food to be cooked, such as changing the heating pattern of the heating coil 11 according to the volume of food to be cooked.

[0096] Furthermore, in the rice cooker of this embodiment, the time T of the non-heated soaking process is A This remains constant regardless of the amount of food being cooked or the setting of the "water hardness" indicator D14, and for a predetermined time T A This method allows rice to absorb water in a reduced pressure environment with room temperature water, enabling water to penetrate deep into the rice grains regardless of the amount of food being cooked or the water hardness setting.

[0097] Furthermore, in the rice cooker of this embodiment, the time T of the heating soaking process as the second soaking process is B The setting may be configured to vary according to the water hardness, and the time T of the heating and soaking process increases as the water hardness of the rice to be cooked increases. B By making the cooking time longer, the rice can be gelatinized all the way to the core even with hard water, allowing for tastier rice cooked according to the water quality.

[0098] Figure 9 shows the changes over time in the rice cooking process of a modified rice cooker of this embodiment, specifically the pot temperature t, which is the temperature detected by the pot temperature sensor 12; the output Po of the side coils 11-1 and bottom coils 11-2; and the pressure Pr' inside the pot 5, which is the pressure detected by the pressure sensor 36. In this modified example, following the preheating and soaking process, a depressurization operation is also performed in the boiling heating process using the depressurization means 38 to reduce the pressure inside the pot 4.

[0099] Referring to the figure, the depressurization operation during the boiling heating process in this modified example will be explained as follows: When the boiling heating process begins, the rice cooking control means 53, based on pressure detection by the pressure sensor 36, opens the path of the depressurization means 38 and operates the vacuum pump 39 continuously to perform vacuuming. Subsequently, when the rice cooking control means 53 receives a detection signal indicating that the pressure inside the pot 4 has reached a certain value or lower in the depressurized state, it stops the operation of the depressurization pump 39 of the depressurization means 38 and controls the path of the depressurization means 28 to close in order to maintain a depressurized state lower than atmospheric pressure inside the pot 4. Therefore, although the pressure inside the pot 4 gradually increases due to heating and slow leaks, the depressurized state can be maintained for a while without operating the depressurization pump 39. This configuration allows for greater water absorption by the rice being cooked by reducing the pressure inside the pot 4 during the boiling heating process. It also allows for greater air to be released from the pot 4, reducing the amount of air dissolved in the water being cooked. This improves the heat conductivity of the water, thereby enhancing the gloss and texture of the cooked rice. Consequently, it is possible to more reliably achieve both enhanced water absorption and a good gloss and texture in the cooked rice.

[0100] As described above, in this modified rice cooker, the depressurization operation, which reduces the pressure inside the pot 4 using the depressurization means 38, is performed not only in the heating and soaking process but also in the boiling heating process, which raises the temperature of the rice to be cooked to boiling point. By reducing the pressure inside the pot 4 in the boiling heating process, the water absorption of the rice to be cooked can be further promoted, and the gloss and texture of the cooked rice can be further improved by reducing the amount of air dissolved in the water of the cooked rice, thus more reliably achieving both good gloss and texture in the cooked rice.

[0101] Figure 10 shows graphs of the changes over time of the pot temperature t, which is the temperature detected by the pot temperature sensor 12, the output Po of the side coil 11-1 and the bottom coil 11-2, and the pressure Pr'' inside the pot 5, which is the pressure detected by the pressure sensor 36, during the rice cooking process of a further modified rice cooker of this embodiment. In this modified version, the inside of the pot 4 is returned to atmospheric pressure at the end of the heating and soaking process, and a depressurization operation is performed in which the inside of the pot 4 is depressurized by the depressurization means 38 during the boiling heating process.

[0102] Referring to the same figure, the depressurization operation during the heating and soaking process and the boiling process of this modified example will be explained. The rice cooking control means 53 receives a time T from the start of the heating and soaking process from the timing means 45. B When the timer signal indicating that the time has elapsed is received, the solenoid 35 is controlled to rotate the pressure regulating valve 34 to open the steam discharge path 33, thereby connecting the inside of the pot 4 to the outside of the main unit 1, and releasing steam from the food being cooked through the steam discharge path 33 to the outside of the main unit 1 through the steam outlet 15. When the cooking control means 53 receives a detection signal from the pressure sensor 36 indicating that the pressure inside the pot 4 has returned to atmospheric pressure, it terminates the soaking process and moves on to the next boiling heating process.

[0103] When the boiling heating process begins, the rice cooking control means 53 receives a detection signal from the pressure sensor 36 indicating that the pressure inside the pot 4 has returned to atmospheric pressure. When it receives a timing signal indicating that a predetermined time has elapsed, such as 10 seconds, it controls the solenoid 35 to close the steam discharge path 33 with the pressure regulating valve 34. Based on the pressure detection by the pressure sensor 36, it opens the path of the depressurization means 38 and operates the vacuum pump 39 continuously to perform vacuuming. This configuration allows the pressure inside the pot 4 to fluctuate, expelling air from inside the rice being cooked and allowing water to permeate in its place, enabling further water absorption into the rice. Furthermore, reducing the pressure inside the pot 4 during the boiling heating process further promotes water absorption by the rice being cooked. Additionally, it allows more air inside the pot 4 to be released outside the machine, reducing the amount of air dissolved in the water being cooked, thereby improving the heat conductivity of the water and enhancing the gloss and texture of the cooked rice. Therefore, it is possible to more reliably achieve both enhanced water absorption and good gloss and texture in the cooked rice. This is just one example, and similar to the preheating and soaking process, the start of heating in the pot 4 and at least the period of the steam discharge path 33 may overlap, or the steam discharge path 33 may be opened after transitioning to the boiling heating process, or both may be performed simultaneously.

[0104] As described above, in this modified rice cooker, the pressure inside the pot 4 is returned to atmospheric pressure at the end of the heating and soaking process, and the depressurization operation, in which the depressurization means 38 reduces the pressure inside the pot 4, is also performed in the boiling heating process that follows the heating and soaking process, in which the temperature of the rice to be cooked is raised to boiling point. This configuration allows for fluctuations in the pressure inside the pot 4, enabling further water absorption into the rice. Furthermore, reducing the pressure inside the pot 4 during the boiling heating process further promotes water absorption by the rice to be cooked, and by reducing the amount of air dissolved in the water of the rice to be cooked, the gloss and texture of the cooked rice can be improved, thus more reliably achieving both good gloss and texture in the cooked rice.

[0105] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, the amount of food to be cooked may be displayed in a selectable format on the display means 18, and the cooking course may be selected and set by selecting these settings with the operating means 19. Alternatively, the capacity determination step may be configured to confirm the amount of food to be cooked. Furthermore, the numerical values ​​and other examples given in the embodiments are merely examples and may be changed as appropriate depending on the specifications of the rice cooker. [Explanation of Symbols]

[0106] 4 Pot 11. Heating coil (heating means) 38 Depressurization means D14 Display for setting "Water Hardness" (Setting of water hardness) T A Time of the non-heated soaking process T B Time of the heating and soaking process

Claims

1. A heating means for heating a pot containing rice and water as the food to be cooked, A rice cooker comprising a pressure reducing means for reducing the pressure inside the pot, In the soaking and cooking process, which raises the temperature of the rice to be cooked to a predetermined temperature, The first soaking step includes a depressurization operation in which the inside of the pot is depressurized by the depressurization means, while the heating means is not driven. A rice cooker characterized in that a heating operation is performed by starting the operation of the heating means from a state of atmospheric pressure inside the pot to heat the pot, and a second soaking step is performed by performing the depressurization operation, in that order.

2. The rice cooker according to claim 1, characterized in that the pressure inside the pot is brought to atmospheric pressure at the start of the second soaking process.

3. The rice cooker according to claim 1 or 2, characterized in that the volume of the rice to be cooked is determined based on the temperature change of the pot in the second soaking step.

4. The rice cooker according to claim 1, characterized in that the depressurization operation is also performed in a boiling heating step that raises the temperature of the rice to be cooked to a boil, following the second soaking step.

5. At the end of the second soaking process, the pressure inside the pot is temporarily returned to atmospheric pressure. The rice cooker according to claim 1, characterized in that the pressure reduction operation is also performed in the boiling heating step, which follows the second soaking step and raises the temperature of the rice to be cooked to a boiling point.

6. The rice cooker according to claim 1, characterized in that the time of the first soaking process is constant regardless of the amount of rice to be cooked or the set water hardness.

7. The rice cooker according to claim 1, characterized in that the time of the second soaking process is varied according to the set water hardness.

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