High-frequency heating conditioner

Abstract

To provide a high-frequency heating cooker that, when a plurality of to-be-heated items are successively heated and cooked, can determine a current placement location of a to-be-heated item, even if a temperature at a placement location etc. of the to-be-heated item has risen during previous execution of heating.SOLUTION: The cooker includes: a range heating unit for heating a to-be-heated item that has been placed onto a table plate; an infrared sensor for detecting temperatures at a plurality of spots on an upper surface of the table plate; an outside temperature sensor for detecting an outside temperature outside a heating chamber; and a control unit for controlling the range heating unit on the basis of a temperature detected by the infrared sensor. The control unit is configured to: calculate a temperature difference between the outside temperature and a backside temperature of the table plate, and a temperature difference between the outside temperature and a front-side temperature of the table plate; use the backside temperature as a table plate temperature if the former temperature difference is small, and use the front-side temperature as the table plate temperature if the latter temperature difference is small; and determine a region of the upper surface of the table plate where there is a temperature difference from the table plate temperature to be a placement region for the to-be-heated item.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a high frequency cooking device that uses microwaves to cook food. [Background technology]

[0002] Some conventional high-frequency cooking devices set the microwave cooking time based on the storage condition of the food placed in the heating chamber. For example, the abstract of Patent Document 1 discloses a high-frequency cooking device that "enables the heating of an object to an appropriate temperature regardless of the storage condition, quantity, or initial surface temperature of the object," and that "includes a heating means for heating the object, a table plate on which the object is placed in the heating chamber, a weight sensor that supports the table plate and measures the weight of the object, a temperature sensor that detects the temperature of the unheated object, and a control means that controls the heating means based on the values ​​detected by the weight sensor and the temperature sensor so that the object reaches the desired temperature. The control means detects a temperature rise during heating of the object with the temperature sensor, determines whether the object is frozen based on the detected temperature rise, calculates a heating time appropriate for the storage condition of the object, and heats the object." Claim 5 of the same document also states that "the temperature sensor is an infrared sensor."

[0003] In this way, the high-frequency cooking device of Patent Document 1 determines whether the object to be heated is frozen or not based on the temperature rise of the object to be heated detected by a non-contact temperature sensor (infrared sensor), and calculates the cooking time based on the determination result, thereby appropriately cooking the object to be heated (see Figures 13 to 15 of the same document). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-211171 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the high-frequency heating device in Patent Document 1 does not anticipate situations in which one food is cooked and then another food is cooked immediately after it, and there are cases in which the latter food cannot be cooked properly. This problem will be specifically explained using the example of a situation in which rice is heated after a side dish is heated.

[0006] In this case, the temperature of the table plate where the side dish is placed also rises when the side dish is heated, so when the side dish is removed after cooking is completed, there will be a portion of the table plate that is hotter than room temperature. If rice is then placed in a position different from where the side dish was placed and cooking begins, the temperature sensor (infrared sensor) in Patent Document 1 cannot determine whether the high-temperature portion of the table plate's top surface is the food to be cooked (the object to be heated). Therefore, the high-frequency heating device in Patent Document 1 may mistake the high-temperature portion of the table plate's top surface (the area where the side dish was placed until just before) for the object to be heated, and may calculate an inappropriate rice heating time based on the temperature change there, which could result in improper heating of the rice.

[0007] Therefore, the present invention aims to provide a high-frequency heating cooker that, when cooking multiple heated objects consecutively, can identify the location where the heated objects are placed this time, even if the temperature of the location where the heated objects are placed has increased during the previous heating. [Means for solving the problem]

[0008] The high-frequency heating cooker of the present invention has been made to achieve the above-mentioned object, and comprises a heating chamber that houses a table plate, a microwave heating unit that heats an object to be heated placed on the table plate, infrared sensors that detect the temperature at multiple locations on the upper surface of the table plate, an outside temperature sensor that detects the temperature outside the heating chamber, and a control unit that controls the microwave heating unit based on the temperature detected by the infrared sensor, and the control unit calculates the temperature difference between the outside temperature and the temperature at the back side of the table plate, and the temperature difference between the outside temperature and the temperature at the front side of the table plate, and if the former temperature difference is small, adopts the back side temperature as the table plate temperature, and if the latter temperature difference is small, adopts the front side temperature as the table plate temperature, and determines the area on the upper surface of the table plate that has a temperature difference from the table plate temperature to be the area where the object to be heated is placed. [Effects of the Invention]

[0009] According to the high-frequency heating cooker of the present invention, when multiple heated objects are successively cooked, the location where the heated objects are placed can be identified even if the temperature of the location where the heated objects are placed has risen during the previous heating. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a front perspective view of a cooking device according to an embodiment; [Figure 2] FIG. 2 is a rear perspective view of the cooking device according to the embodiment with the outer frame removed. [Figure 3] Cross section AA of Figure 1 [Figure 4] In Figure 3, the operation of the infrared sensor when heating cold rice in a bowl is explained. [Figure 5] In Figure 3, this is an explanatory diagram of the operation of the infrared sensor when heating frozen rice wrapped in plastic wrap. [Figure 6] FIG. 4 is an enlarged cross-sectional view illustrating a reference position of an infrared sensor. [Figure 7] FIG. 4 is an enlarged cross-sectional view illustrating the end point position of the infrared sensor. [Figure 8]FIG. 4 is an enlarged cross-sectional view illustrating a state in which the observation window of the infrared sensor is closed. [Figure 9] FIG. 3 is an explanatory diagram illustrating a temperature measurement area of ​​an infrared sensor. [Figure 10] 4 is a flowchart illustrating the first stage of control of a cooking device according to an embodiment. [Figure 11] 10 is a flowchart illustrating the latter stage of the control of the cooking device according to one embodiment. [Figure 12] FIG. 2 is a control block diagram of a cooking device according to an embodiment. [Figure 13] FIG. 4 is a diagram illustrating a heating time of a cooking device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] 1 to 3 show the main parts of this embodiment, with FIG. 1 being a perspective view of the cooking device body as seen from the front side, FIG. 2 being a perspective view of the cooking device body as seen from the rear side with the outer frame removed, and FIG. 3 being a cross-sectional view taken along the line AA in FIG. 1.

[0013] In the figure, the main body 1 of the cooking device has food to be heated placed in a heating chamber 28, and the food is cooked using microwaves, heat from a heater, or superheated steam.

[0014] Door 2 is opened and closed to put food in and take food out of heating chamber 28, and closing door 2 seals heating chamber 28, preventing leakage of microwaves used to heat food and sealing in heater heat and superheated steam, enabling efficient heating.

[0015] The handle 9 is attached to the door 2 to facilitate opening and closing the door 2, and is shaped to be easy to grip with the hand.

[0016] The glass window 3 is attached to the door 2 so that the state of the food being cooked can be checked, and is made of glass that can withstand high temperatures caused by heat generated by a heater or the like.

[0017] The input unit 71 is provided on the operation panel 4 on the lower front side of the door 2, and is composed of an operation unit 6 for inputting the heating unit such as microwave heating or heater heating, the heating time, etc., and the heating temperature, and a display unit 5 for displaying the content input from the operation unit 6 and the progress of cooking.

[0018] The outer frame 7 is a cabinet that covers the top surface and the left and right side surfaces of the main body 1 of the cooking appliance.

[0019] The water tank 42 is a container for storing the water needed to make heated steam, and is provided on the lower front side of the main body 1 of the cooking device. It is designed to be detachable from the front of the main body 1, making it easy to supply and drain water.

[0020] The rear panel 10 forms the rear surface of the cabinet, and has an external exhaust duct 18 attached to the top, through which steam emitted from food and cooling air (waste heat) 39 after cooling the internal parts of the main body 1 are discharged from the external exhaust port 8 of the external exhaust duct 18.

[0021] The machine chamber 20 is provided in the space between the bottom surface 28a of the heating chamber and the bottom plate 21 of the main body 1, and on the bottom plate 21 are mounted a magnetron 33 for heating food, a waveguide 47 connected to the magnetron 33, a control board 23 on which a control unit 23a (see Figure 12) is mounted, various other components described below, a fan unit 15 for cooling these various components, etc.

[0022] Heating chamber bottom surface 28a has a recessed shape in the approximate center, within which rotating antenna 26 is installed, and microwave energy radiated from magnetron 33 flows into the underside of rotating antenna 26 through waveguide 47 and opening 47a through which output shaft 46a of rotating antenna 26 passes, where it is diffused by rotating antenna 26 and radiated into heating chamber 28. Output shaft 46a of rotating antenna 26 is connected to rotating antenna driver 46.

[0023] The fan unit 15 is composed of a cooling fan attached to a cooling motor attached to the bottom plate 21. The cooling air 39 generated by this fan unit 15 cools the self-heating magnetron 33, inverter circuit (not shown), rear weight sensor 25c, left weight sensor 25b, and other components in the machine chamber 20. The cooling air 39 also flows between the outside of the heating chamber 28 and the outer frame 7, and between the hot air case 11a and the rear plate 10, as described above, cooling the outer frame 7 and the rear plate 10, before being discharged from the external exhaust port 8 of the external exhaust duct 18. Furthermore, a duct 16a for cooling the hot air motor 13 (described later) and a duct 16b for cooling the infrared unit 50 housed in the infrared case 48 (described later) are provided. The cooling air 39 that has cooled the infrared unit 50 is discharged from the opposite side of the exhaust duct 28e, which dissipates waste heat (such as water vapor) from the heating chamber 28, and then discharged to the outside through the external exhaust duct 18.

[0024] The microwave heating unit 330 (FIG. 12) is made up of a magnetron 33 and an inverter circuit (not shown) and is controlled by the control unit 23a. The temperature of the IGBT (not shown) in the inverter circuit is detected by the IGBT temperature sensor 101.

[0025] A hot air unit 11 is attached to the rear of the heating chamber 28, and a hot air fan 32 is attached within the hot air unit 11 to efficiently circulate the air within the heating chamber 28. A hot air intake hole 31 and a hot air outlet hole 30 are provided on the rear wall surface 28b of the heating chamber as air passages.

[0026] The hot air fan 32 is rotated by the drive of a hot air motor 13 attached to the outside of the hot air case 11a, and heats the circulating air with a hot air heater .

[0027] In addition, the hot air unit 11 has a hot air case 11a on the rear side of the inner wall surface 28b of the heating chamber, a hot air fan 32 between the inner wall surface 28b of the heating chamber and the hot air case 11a, and a hot air heater 14 positioned on its outer periphery, and a hot air motor 13 attached to the rear side of the hot air case 11a, with the motor shaft connected to the hot air fan 32 through a hole provided in the hot air case 11a.

[0028] The hot air motor 13 rises in temperature due to heat from the heating chamber 28 and the hot air heater 14, so to prevent this, it is surrounded by a hot air motor cover 17, and a roughly cylindrical duct 16a is positioned between the hot air case 11a and the rear panel 10, with the upper end opening of the duct 16a connected to the underside of the hot air motor cover 17 and the lower end opening connected to the outlet of the fan device 15, so that part of the cooling air 39 from the fan device 15 is taken into the hot air motor cover 17.

[0029] Grill heating unit 12, which consists of a heater, is attached to the back side of heating chamber top surface 28c of heating chamber 28. Grill heating unit 12 is formed into a flat shape by wrapping a heater wire around a mica plate and is fixed by pressing it against the back side of the top surface of heating chamber 28. It heats the top surface of heating chamber 28 and grills food inside heating chamber 28 by radiant heat.

[0030] In addition, an infrared unit 50 (described later) is provided at the back of the heating chamber ceiling 28c of the heating chamber 28, and is covered with an infrared case 48 to cool the infrared unit 50. The duct 16b is formed in an approximately cylindrical shape and is positioned between the hot air case 11a and the rear panel 10, with the upper opening of the duct 16b connected to the side of the infrared case 48 and the lower opening connected to the top surface of the hot air motor cover 17, and is designed to take in part of the cooling air 39 from the fan device 15.

[0031] An internal temperature sensor 80 (thermistor) for detecting the ambient temperature of the heating chamber (hereinafter referred to as "internal temperature Ti") is provided on the left rear side of the heating chamber top surface c of the heating chamber .

[0032] In addition, the bottom surface 28a of the heating chamber is provided with a plurality of weight sensors 25, for example, a left weight sensor 25b on the left and right sides of the front, a right weight sensor (not shown), and a rear weight sensor 25c in the center of the rear, on which the table plate 24 is placed.

[0033] The table plate 24 is used to place food on, and is made of a heat-resistant material that can be used for both heater heating and microwave heating, and is also highly permeable to microwaves.

[0034] The boiler 43 is attached to the outer surface of the hot air case 11a of the hot air unit 11, and directs saturated steam toward the inside of the hot air unit 11. The saturated steam ejected into the hot air unit 11 is heated by the hot air heater 14 to become superheated steam.

[0035] The pump unit 87 pumps water from the water tank 42 up to the boiler 43, and is composed of a pump and a motor that drives the pump. The amount of water supplied to the boiler 43 is adjusted by the ON / OFF ratio of the motor.

[0036] The heating section includes a range heating section 330, a hot air heater 14, a hot air motor 13, a grill heating section 12, a boiler 43, and the like.

[0037] Next, the infrared sensor 52 that is provided above the heating chamber 28 and detects the temperature of the object to be heated in a non-contact manner will be described in detail with reference to FIGS.

[0038] Figure 4 is an explanatory diagram of the operation of the infrared sensor when rice is placed in a bowl and heated, using the cross-sectional view shown in Figure 3; Figure 5 is an explanatory diagram of the operation of the infrared sensor when frozen rice wrapped in plastic wrap is heated, using the cross-sectional view shown in Figure 3; Figure 6 is an enlarged view of the infrared sensor showing the reference position; Figure 7 is an enlarged view of the infrared sensor showing the end position; Figure 8 is an enlarged view of the infrared sensor with the observation window closed; and Figure 9 is an explanatory diagram explaining the field of view of the infrared sensor.

[0039] Reference numeral 51 denotes a motor, which is attached so that its rotation axis 51a is parallel to the heating chamber inner wall surface 28b. The rotation axis 51a rotates (drives) a cylindrical unit case 54 (described later), which rotates a board 53 on which an infrared sensor 52 housed in the unit case 54 is mounted, thereby rotating the orientation of the lens portion 52a of the infrared sensor 52 within a range from the inner side of the heating chamber bottom surface 28a (the heating chamber inner wall surface 28b side) to the heating chamber opening 28d, thereby enabling temperature detection. The motor 51 uses a stepping motor, and the rotation axis 51a can be rotated forward or backward and at any desired rotation angle under the control of a control unit 23a provided on the control board 23.

[0040] Reference numeral 52 denotes an infrared sensor that detects the temperature of the table plate 24 and the object to be heated 60c in a non-contact manner. In this embodiment, the infrared sensor 52 is configured by arranging eight infrared detection elements (for example, thermopiles) in a row on a substrate 53 in the direction of the rotation axis 51a. Therefore, the infrared sensor 52 of this embodiment can simultaneously detect the temperature of eight locations on the table plate 24. Furthermore, the infrared sensor 52 of this embodiment can detect the temperature of the entire area of ​​the table plate 24 by rotating the substrate 53 on which the infrared detection elements are mounted around the rotation axis 51a (see Figures 6 and 7).

[0041] Reference numeral 54 denotes a cylindrical unit case, in which the substrate 53 is disposed at the maximum diameter portion and a window 54a is provided through which the lens portion 52a of the infrared sensor 52 is visible. In addition, the material of the unit case 54 contains carbon, which makes the unit case 54 conductive and prevents external noise from entering the unit case 54.

[0042] Reference numeral 55 denotes a shutter made of a metal plate. The shutter 55 closes an observation window 44a (described later) when the infrared sensor 52 is not in use (see FIG. 8). In addition, in order to prevent the temperature of the heating chamber 28 from being transmitted to the unit case 54, the shutter 55 is arranged to form an air passage 55c with gaps provided along the outer periphery of the unit case 54 so that cooling air can flow around the outer periphery of the unit case 54, and openings 55a and 55b are provided in the air passage 55c as entrances and exits for the flow of the cooling air 39.

[0043] Reference numeral 56 denotes a positioning protrusion, and when the control unit 23a controls the rotation of the motor 51 so as to align the detection point of the infrared sensor 52 with the reference position (detection point a in FIG. 4), the reference position of the detection point of the infrared sensor 52 can be corrected. When the observation window 44a is closed by the shutter 55, the positioning protrusion 56 is brought into contact with a stopper (not shown) provided on the infrared case 48, and the rotation shaft 51a is caused to slip, thereby correcting the reference position controlled by the control unit 23a and the position of the detection point a, which is the reference position detected by the infrared sensor 52. Reference numeral 44 denotes an arc-shaped observation section that protrudes inward into heating chamber 28, and the rotation center of rotation shaft 51a, the center of cylindrical unit case 54, the center of the arc of shutter 55 that is provided along the outer periphery of unit case 54 and bent into an arc, and the center position of arc-shaped observation section 44 are all coincident. Reference numeral 44a denotes an observation window provided in observation section 44, which opens over a range that becomes the field of view detected by infrared sensor 52. In addition, to prevent microwave leakage from observation window 44a during microwave heating, a raised wall (burring) 44b of about 2 mm is provided on the outer periphery of observation window 44a.

[0044] By projecting the observation section 44 into the inside of the heating chamber 28, it becomes possible to detect temperatures over a wide range with a minimum narrow observation window opening range.

[0045] Reference numeral 49 denotes a convex portion which separates the infrared case 48 and the infrared unit 50 from the heating chamber top surface 28c, and by having only the convex portion 49 come into contact with the heating chamber top surface 28c, the temperature of the heating chamber top surface 28c heated by heaters such as the grill heating section 12 and the hot air unit 11 during heating is less likely to be transmitted to the infrared unit 50.

[0046] Reference numeral 100 denotes an outside-compartment temperature sensor disposed on substrate 53 inside infrared unit 50, which detects outside-compartment temperature To outside heating chamber 28. When multiple objects to be heated are heated consecutively, the outside-compartment temperature To measured before the start of the first heating is approximately equal to the room temperature outside the cooking device, and the outside-compartment temperature To measured before the start of the second or subsequent heating is higher than the room temperature outside the cooking device but lower than inside-compartment temperature Ti.

[0047] The measurement procedure of the infrared sensor 52 of the control unit 23a mounted on the control board 23 will be described with reference to FIGS.

[0048] Fig. 4 illustrates the operation of the infrared sensor when heating rice in a bowl, and Fig. 5 illustrates the operation of the infrared sensor when heating frozen rice wrapped in plastic wrap. In Fig. 4, the surface of the object to be heated 60c can be directly detected at detection point f. In Fig. 5, the surface of the object to be heated 60c is detected through the food wrap.

[0049] Infrared sensor 52 measures eight points at a time, and is rotated 14 times by three degrees from the reference position (detection point a in Figure 4) to the end position (detection point h in Figure 4) by motor 51, measuring a total of 15 rows, detecting the temperature at 120 locations (8 points in the left-right direction x 15 rows in the front-back direction).Then, from the end position to the reference position, infrared sensor 52 returns directly to the reference position without taking any measurements.

[0050] The temperature is detected by moving the infrared sensor 52 from the reference position to the end position by 3 degrees 14 times, measuring in 15 rows, and then returning from the end position to the reference position. The processing of the measured temperature will be described later.

[0051] Next, the rotational movement of the infrared sensor 52 will be described.

[0052] When a bowl containing the food to be heated (rice) 60c is placed on the table plate 24 provided on the bottom surface 28a of the heating chamber as shown in Figure 4 and heating is started, the observation window 44a is closed by the shutter 55 for 1 to 2 seconds until the magnetron 33 stabilizes its emission (see Figure 8), preventing noise caused by unstable emission at the start of the magnetron 33's emission from entering the infrared sensor 52.

[0053] After the transmission of magnetron 33 has stabilized, control unit 23a controls motor 51 to rotate shaft 51a to the reference position. Rotation of shaft 51a to the reference position rotates unit case 54, and lens 52a of infrared sensor 52 also rotates to a position where it can detect detection point a at the reference position (see FIGS. 4 and 6). At this time, cooling air 39 flows through lens 52a of infrared sensor 52 and through sensor window 44a into heating chamber 28, preventing dirt from adhering to lens 52a.

[0054] By rotating the unit case 54, the detection of the temperature of the object to be heated 60c progresses from the aforementioned reference position (detection point a) to detection point b and detection point c on the table plate 24, and as the unit case 54 continues to rotate, the temperature of the outside of the bowl (container 60) is detected in the height direction, and the temperature is detected from detection point d to detection point e. After the detection point reaches the top of the opening of the bowl (container 60), the temperature of the surface of the object to be heated 60c is detected at detection point f, then the temperature of the inside of the bowl (container 60) is detected at detection point g, and then the temperature of the table plate 24 is detected at detection point h.

[0055] The temperature detection range from detection point a to detection point h is detected on one side of the forward path of the unit case 54 as it rotates, and once the temperature detection is completed up to the end point, no measurements or temperature detection are performed on the return path, and the temperature is again detected sequentially from detection point a to detection point h after returning to the reference position.

[0056] The number of temperature detections can be changed as desired, and the above-mentioned detection points a to h are illustrative examples, and 15 columns of data are measured as described above.

[0057] Furthermore, the temperature is detected by stopping the rotation of the motor 51 while the temperature is being detected, and then restarting the rotation after the temperature is detected. In order to detect the temperature accurately, it is better to measure the temperature while the rotation is stopped.

[0058] For example, at the beginning of heating, the rotation of the unit case 54 is stopped and detection is performed, and after detection, the rotation is rotated at a fixed angle, the rotation is stopped and detection is performed, and after detection, the rotation is rotated at a fixed angle again, and this process is repeated to measure the temperature distribution in a grid pattern. By doing so, the temperature is measured at fixed positions at equal angles, and the entire surface of the table plate 24 is measured evenly.

[0059] The infrared sensor 52 is provided at approximately the center in the left-right direction of the heating chamber top surface 28c inside an imaginary line extending perpendicularly from the four sides of the table plate 24 placed on the heating chamber bottom surface 28a to the heating chamber top surface 28c.

[0060] The field of view of the infrared sensor 52 is set so that detection points a and h are approximately set to a range that detects the temperatures of the front and rear flange portions of the table plate 24, and the sensors on both sides of the aligned multiple elements of the infrared sensor 52 are approximately set to a range that detects the temperatures of the left and right flange portions of the table plate 24. This makes it possible to accurately detect the temperature of the object to be heated 60c placed approximately in the center of the table plate 24. Furthermore, it is better to rotate the infrared sensor 52 in the direction that provides a wider temperature measurement range in order to detect the temperature of the object to be heated 60c placed in the container 60.

[0061] With this setting, when the container 60 is placed at the back of the table plate 24, the temperature of the heated object 60c in the bowl can be detected at detection point b, which is approximately below the infrared sensor 52.When the container 60 is placed on one of the left and right sides of the table plate 24, the infrared sensor 52 is located approximately in the center of the heating chamber 28 in the left-right direction, so the infrared sensors on both sides of the eight elements aligned in a row within the infrared sensor 52 can detect the temperature of the heated object 60c.

[0062] Furthermore, when the weight information from the weight sensor 25 and the temperature distribution information detected by the infrared sensor 52 indicate that the weight information is light and the temperature distribution shows a wide temperature rise, it can be determined that the object 60c to be heated is thin and wide.

[0063] In this embodiment, a method for detecting the temperature of the heated object 60c placed in the container 60 has been described in detail. However, even if the heated object 60c is a large block-shaped lump without a container, the temperature of the side height direction and the top surface of the block-shaped heated object 60c can be detected, making it possible to detect the temperature distribution of the heated object 60c in detail.

[0064] <Temperature measurement procedure of infrared sensor 52> Next, the processing of the temperature measured by the infrared sensor 52 will be described.

[0065] First, we will explain the issues that arise when measuring the temperature of the object to be heated 60c on the table plate 24 using the infrared sensor 52. The infrared detection element (thermopile) used in the infrared sensor 52 of this embodiment is an element that outputs the average value of the temperature of the object to be measured within its field of view as the detected temperature. Therefore, when the object to be heated 60c and the table plate 24 are present within the field of view of the infrared detection element, not only the temperatures of the two but also the area ratio between them within the field of view will be reflected in the measured temperature.

[0066] The infrared sensor 52 of this embodiment measures the upper surface of the table plate 24 by dividing it into multiple regions so as to be able to recognize the approximate size and shape of the object 60c to be heated placed on the table plate 24. For example, if the infrared sensor 52 has eight infrared detection elements, the rotation shaft 51a of the motor 51 is moved 14 times by three degrees each, thereby dividing the upper surface of the table plate 24 into 120 (8 x 15) regions and measuring the temperature, as shown in FIG.

[0067] Hereinafter, each of the 120 squares shown in Fig. 9 will be referred to as a pixel. This pixel is set at a viewing angle that is approximately 50% or more of the directional characteristics of the infrared sensor 52. However, the output from the infrared sensor 52 includes all objects to be measured that are within the viewing angle (100% viewing angle), as follows: the pixel with a viewing angle that is 50% or more of the directional characteristics, multiple pixels adjacent to that pixel, and the wall surfaces of the heating chamber 28 other than the table plate 24. For this reason, it is necessary to correct the detected temperature to approximately calculate the temperature of the object to be heated 60c.

[0068] The information required for the correction is the table plate temperature Tt, and the recognition (determination) of the object to be heated 60c, as well as the size and temperature of the recognized object to be heated 60c.

[0069] Here, the table plate temperature Tt is determined by detecting the rear temperature Tb (average temperature of the rear 8 pixels) and the front temperature Tf (average temperature of the front 8 pixels) of the table plate 24, and then determining the temperature suitable for use as the table plate temperature Tt. Details of which temperature to select as the table plate temperature Tt will be described later.

[0070] <How to recognize heated object 60c> Next, a method for recognizing the object to be heated 60c based on the measured temperature of each pixel, and the size and temperature of the recognized object to be heated 60c will be described.

[0071] The object to be heated 60c is recognized by recognizing pixels having a temperature difference of a predetermined value or more with respect to the table plate temperature Tt (i.e., the backside temperature Tb or frontside temperature Tf of the table plate 24) as the object to be heated 60c. However, since the object to be heated 60c may be at a wide range of temperatures, such as frozen, refrigerated, or room temperature, the following determination method is used to recognize the object to be heated 60c.

[0072] Since cooking appliances are mainly placed in kitchens, the temperature of the cooking appliance is approximately the same as room temperature except immediately after it is used for heating.

[0073] If the object 60c is frozen or refrigerated, the temperature of the object 60c is lower than the table plate temperature Tt. To accurately recognize the object 60c, the object 60c is determined to have been recognized if the minimum temperature of each detected pixel is lower than the table plate temperature Tt by a specific temperature. The size of the object 60c is recognized as the collection of pixels that indicate temperatures within a predetermined temperature range corresponding to the difference between the minimum temperature and the table plate temperature Tt (e.g., the shaded area in Figure 9). The minimum temperature is recognized as the temperature of the object 60c, and the detected temperature of the object 60c is corrected according to the emissivity of the object 60c to calculate the initial temperature of the object 60c. The detected temperature is corrected according to the emissivity because, even if the temperature of the object 60c is the same, the temperature measured by the infrared sensor 52 will differ if the emissivity differs, and therefore temperature correction according to the emissivity is necessary. The emissivity of the object to be heated 60c can be specified according to the set menu.

[0074] On the other hand, when the temperature of the heated object 60c is higher than the table plate temperature Tt, in order to accurately recognize the heated object 60c, it is determined that the heated object 60c has been recognized if the maximum temperature of each detected pixel is higher by a specific temperature than the table plate temperature Tt. The size of the heated object 60c is recognized as the collection of pixels that indicate temperatures within a predetermined temperature range corresponding to the difference between the maximum temperature and the table plate temperature Tt. The maximum temperature is recognized as the temperature of the heated object 60c, and the detected temperature of the heated object 60c is corrected according to the emissivity of the heated object 60c to calculate the initial temperature of the heated object 60c.

[0075] Furthermore, when the heated object 60c is at room temperature, the table plate temperature Tt and the temperature of the heated object 60c are equal. Therefore, no specific temperature difference can be determined between the temperature of each detected pixel and the table plate temperature Tt. Therefore, if the heated object 60c is not determined to be on either the side of the specific temperature difference assumed when the heated object 60c is frozen or refrigerated, or the side of the temperature difference assumed when the heated object 60c is higher than the table plate temperature Tt, the entire area of ​​the table plate temperature Tt is recognized as the heated object 60c. Then, when the heated object 60c is heated, its temperature rises, and the temperature at the position where this rise exceeds a specific temperature is recognized as the detected temperature of the heated object 60c, and the collection of pixels where the specific temperature rise is recognized as the size of the heated object 60c. In this case, too, the detected temperature of the heated object 60c is corrected according to the emissivity of the heated object 60c and calculated as the initial temperature of the heated object 60c.

[0076] <Flowchart of microwave heating control> Next, microwave heating control by the cooking device of this embodiment will be described with reference to the flowcharts of FIGS.

[0077] In this microwave heating control, the table plate temperature Tt is mainly determined in the first part of the flowchart shown in FIG. 10, and the microwave heating mode is mainly determined in the second part of the flowchart shown in FIG.

[0078] 10, the user opens the door 2 of the heating chamber 28, places the container 60 containing the object to be heated 60c on the table plate 24, and then closes the door 2. Then, the user uses the input unit 71 to select an automatic menu.

[0079] Next, in step S2, the user adjusts the cooking finish using the input unit 71. Specifically, from the prepared finish adjustment K, the user selects one of "strong," "slightly strong," "medium," "slightly weak," or "weak." Here, "medium" of the finish adjustment K is finished at the standard temperature, "strong" is finished at a higher temperature, and "weak" is finished at a lower temperature.

[0080] In step S3, the user presses the start button on the input unit 71.

[0081] In step S4, the weight sensor 25 detects the total weight W of the object to be heated 60c and the container 60 placed on the table plate .

[0082] In step S5, the inside temperature sensor 80 detects the inside temperature Ti.

[0083] In step S6, the control unit 23a determines whether the internal temperature Ti is higher than a predetermined temperature. If the internal temperature Ti is higher than the predetermined temperature, the control unit 23a shifts to the internal high temperature mode and heats the object to be heated 60c. If not, the control unit 23a proceeds to step S7.

[0084] Here, the high temperature inside mode is a mode in which microwave heating is performed without using the infrared sensor 52 when the temperature of the heating chamber 28 is high, such as immediately after oven cooking, because the infrared sensor 52 cannot accurately detect the temperature of the object 60c to be heated. Therefore, in this mode, the user selects via the input unit 71 whether the object 60c is stored at room temperature / refrigerated or frozen, and based on this selection result and the detected weight W, the total heating time is calculated based on the results of a prior confirmation of the heating time required to heat the object 60c to the input temperature, and then the object is heated.

[0085] In step S7, the infrared sensor 52 detects the back temperature Tb and the front temperature Tf of the top surface of the table plate (see FIG. 9), and the outside temperature sensor 100 detects the outside temperature To outside the heating chamber .

[0086] In step S8, the control unit 23a compares the temperature difference between the rear temperature Tb and the outside temperature To, and the temperature difference between the front temperature Tf and the outside temperature To, and if the former temperature difference is smaller, proceeds to step S9, and if the latter temperature difference is smaller, proceeds to step S10.

[0087] In step S9, the control unit 23a adopts the inner temperature Tb, which is closer to the outside temperature To, as the table plate temperature Tt.

[0088] On the other hand, in step S10, the control unit 23a adopts the front-side temperature Tf, which is closer to the outside-compartment temperature To, as the table plate temperature Tt.

[0089] Next, in step S11 of Fig. 11, the control unit 23a determines the placement area of ​​the object 60c based on the temperature of each pixel on the upper surface of the table plate. This step identifies the placement area of ​​the object 60c, as exemplified by the shaded area in Fig. 9.

[0090] In step S12, the control unit 23a determines whether the table plate temperature Tt adopted in step S9 or step S10 is higher than a predetermined temperature. If the table plate temperature Tt is high, the process proceeds to step S16; if not, the process proceeds to step S13. Note that if the table plate temperature Tt is determined to be high in this step, it can be assumed that the table plate temperature Tt has become high as a result of another microwave cooking operation being performed immediately before the current microwave cooking operation.

[0091] In step S13, the control unit 23a determines whether the IGBT temperature detected by the IGBT temperature sensor 101 is higher than a predetermined temperature. If the IGBT temperature is high, the process proceeds to step S14; if not, the process proceeds to step S15. If the IGBT temperature is determined to be high in this step, it can be assumed that the IGBT supplying power to the microwave heating unit 330 has become hot as a result of another microwave cooking being performed immediately before the current microwave cooking.

[0092] In step S14, the control unit 23a determines whether the maximum temperature among the temperatures of each pixel on the top surface of the table plate measured by the infrared sensor 52 is higher than the temperature obtained by adding a predetermined temperature to the outside oven temperature To. If the maximum temperature is high, the process proceeds to step S16; if not, the process proceeds to step S15. If the top surface of the table plate is determined to be locally high in this step, it can be assumed that another microwave cooking operation was performed immediately before the current microwave cooking operation, resulting in a locally high temperature on the top surface of the table plate due to the heat of the previously heated object.

[0093] In step S15, the control unit 23a detects the initial temperature Ts of the object 60c based on the temperature measured by the infrared sensor 52 at the pixel determined to be the object region in step S11, and classifies the storage state of the object 60c as frozen, refrigerated, or room temperature based on the initial temperature Ts. Then, cooking is performed in the normal heating mode according to the classified state of the object 60c. The normal heating mode is selected when the infrared sensor 52 can correctly detect the temperature of the object 60c, and similar to conventional heating control, heating is terminated when the temperature of the object 60c reaches a desired cooking end temperature.

[0094] In step S16, the control unit 23a detects the initial temperature Ts of the object 60c based on the temperature measured by the infrared sensor 52 at the pixel determined to be the object region in step S11, and classifies the storage state of the object 60c as frozen or not frozen based on the initial temperature Ts. Then, cooking in the high temperature placement mode is performed depending on the classified state of the object 60c.

[0095] The high temperature placement mode is a heating mode in which, when there are traces of another heated object being cooked in the microwave immediately before the current microwave cooking (the back or front of the table plate is hot, or the table plate is locally hot), and these traces could cause the infrared sensor 52 to misinterpret the temperature of the heated object 60c, the microwave heating time is calculated to heat the heated object 60c to an appropriate temperature based on the weight W detected in step S4 and the storage state determined in step S16.

[0096] Here, microwave heating when the high temperature placement mode is selected will be explained using Figure 13. When the high temperature placement mode is selected, the total heating time is the sum of the first sensing time t1 and the second microwave heating time t2. The first sensing time t1 is the period for performing the sensing process, during which the weight W and storage state of the object to be heated 60c are determined. Meanwhile, the second microwave heating time t2 is calculated using one of the following formulas based on the weight W and storage state of the object to be heated 60c determined by sensing.

[0097] <When the food to be heated is frozen> t2a=k1×(k2-k3×Ts)×W (Formula 1) <If the item to be heated is not frozen (refrigerated or room temperature)> t2b=k1×(k4-k5×Ts)×W (Formula 2) Here, k1 is a coefficient according to the setting of the doneness adjustment K, for example, 1.5 for the "strong" setting, 1.2 for the "slightly strong" setting, 1 for the "medium" setting, 0.8 for the "slightly weak" setting, and 0.5 for the "weak" setting. Also, k2 to k5 are predetermined positive numbers, and are set to values ​​that always make t2a in Equation 1 and t2b in Equation 2 positive when the initial temperature Ts of the object to be heated is equal to or lower than the cooking completion temperature.

[0098] As a result, as long as the storage state of the heated object 60c can be classified as frozen or not frozen, even if the temperature of the heated object 60c cannot be accurately measured due to traces of previous microwave heating, the microwave heating time t2 required to heat the heated object 60c to the appropriate temperature can be calculated, and the heated object 60c can be heated to the appropriate temperature by using the microwave heating time t2.

[0099] As described above, according to the high-frequency heating cooker of this embodiment, when multiple heated objects are successively cooked, even if the temperature of the place where the heated objects are placed has risen during the previous heating, the location where the current heated object is placed can be identified, and the current heated object can be heated to an appropriate temperature. [Explanation of symbols]

[0100] 1 Cooking appliance body, 23a control section, 24 table plates, 25 weight sensors, 28 heating chamber, 33 magnetron, 52 infrared sensor, 60 containers, 60c Heated object, 71 input section, 80 Internal temperature sensor, 100 Outside temperature sensor, 101 IGBT temperature sensor, Ti: Chamber temperature, To outside temperature, Tt table plate temperature, Tf is the temperature on the front side of the table plate, Tb: Temperature at the back of the table plate Ts Initial temperature of the heated object

Claims

1. a heating chamber containing a table plate; a microwave heating unit that heats a frozen or refrigerated object placed on the table plate; an infrared sensor for detecting the temperature at a plurality of points on the top surface of the table plate; an outside temperature sensor for detecting the temperature outside the heating chamber; a control unit that controls the microwave heating unit based on the temperature detected by the infrared sensor, The control unit Calculating a temperature difference between the temperature outside the chamber and the temperature at the rear side of the table plate, and a temperature difference between the temperature outside the chamber and the temperature at the front side of the table plate; If the former temperature difference is smaller than the latter temperature difference, the deep side temperature is adopted as the table plate temperature, If the latter temperature difference is smaller than the former temperature difference, the front side temperature is adopted as the table plate temperature; A high frequency heating cooker, characterized in that an area on the upper surface of the table plate that is at a temperature lower than the temperature of the table plate by a specific amount is determined as the area where the object to be heated is placed.

2. The high frequency cooking device according to claim 1, When the table plate temperature is higher than a predetermined temperature, the control unit A high-frequency heating cooker characterized by classifying the storage state of the heated object as frozen or not based on the initial temperature detected by the infrared sensor, calculating the heating time according to the storage state, and controlling the microwave heating unit.

3. The high frequency cooking device according to claim 1, Further, an IGBT temperature sensor is provided for detecting an IGBT temperature of the range heating unit, When the table plate temperature is not higher than a predetermined temperature, the control unit When the IGBT temperature is higher than a predetermined temperature and the maximum temperature of the temperatures of the top surface of the table plate detected by the infrared sensor is higher than the predetermined temperature, A high-frequency heating cooker characterized by classifying the storage state of the heated object as frozen or not based on the initial temperature detected by the infrared sensor, calculating the heating time according to the storage state, and controlling the microwave heating unit.

4. The high frequency cooking device according to claim 2 or 3, Further, a weight sensor for detecting the weight of the object to be heated is provided, The high frequency heating cooker, wherein the control unit calculates a heating time according to the weight and controls the microwave heating unit.

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