EP0093172A1 - Dispositif de chauffage a haute frequence - Google Patents

Dispositif de chauffage a haute frequence Download PDF

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Publication number
EP0093172A1
EP0093172A1 EP82901428A EP82901428A EP0093172A1 EP 0093172 A1 EP0093172 A1 EP 0093172A1 EP 82901428 A EP82901428 A EP 82901428A EP 82901428 A EP82901428 A EP 82901428A EP 0093172 A1 EP0093172 A1 EP 0093172A1
Authority
EP
European Patent Office
Prior art keywords
high frequency
temperature
humidity
heating
exhaust
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82901428A
Other languages
German (de)
English (en)
Other versions
EP0093172A4 (fr
Inventor
Akihiko Ueno
Kiyoshige Watanabe
Mitsuo Akiyoshi
Kenji Watanabe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Publication of EP0093172A1 publication Critical patent/EP0093172A1/fr
Publication of EP0093172A4 publication Critical patent/EP0093172A4/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/647—Aspects related to microwave heating combined with other heating techniques
    • H05B6/6482—Aspects related to microwave heating combined with other heating techniques combined with radiant heating, e.g. infrared heating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/642—Cooling of the microwave components and related air circulation systems
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/6447—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors
    • H05B6/645—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors using temperature sensors
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/6447—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors
    • H05B6/6458—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors using humidity or vapor sensors

Definitions

  • the present invention relates to a high frequency heating apparatus intended for automation of cooking by using a combination of a microcomputer and various sensors.
  • microwave ovens capable of automatic cooking have made their advent and are in the limelight. Further, there is a proposal to control the finished state of food.
  • the humidity sensor used in microwave ovens designed for automatic cooking by detecting vapor from food has a stabilized characteristic hardly responsive to seasonings, alcohols and other impurities ditterent from vapor, but since the temperature ot the atmosphere around the humidity sensor varies with the progress of cooking, even if changes in humidity due to vapor from food can be detected, it has been impossible to detect a predetermined amount of change. In the case where the amount of vapor from food is very small as in thawing, rises in the temperature ot the atmosphere around the humidity sensor relatively lower the rate ot change of relative humidity, thus making it impossible to detect a predetermined amount of change.
  • An object of the invention is to provide an arrangement wherein the temperature of the exhaust from the heating chamber is made constant and the humidity is detected, thereby accurately detecting the time required to reach a tixed amount of change in relative humidity due to water vapor from food, so as to effect automatic cooking and automatic thawing without using any wrap or special container for food.
  • Another object of the invention is to provide an arrangement wherein high frequency oscillation is intermittently controlled to control the output so as to heat a large food uniformly to the interior thereof, while the output of a heater for making constant the exhaust temperature is switched to a low output when the high frequency oscillator is oscillated at the time of intermittent control and to a high output when it is not oscillated, thereby keeping down the maximum consumption current and consumption power to cut down the cost, and wherein the apparatus is adapted to be used with a household plug receptacle and is convenient to use.
  • a further object of the invention is to provide an arrangement wherein the atmosphere temperature at the start of cooking is detected and one of predetermined exhaust control temperatures is selected according to the size ot said atmosphere temperature to avoid reckless use of high temperature for control, and wherein rises in the temperatures of electric parts including a magnetron are used as an auxiliary heat source to reduce the power cost.
  • a high frequency heating apparatus of the present invention comprises a heater installed adjacent the suction port of the heating chamber, a temperature sensor and a humidity sensor which are installed adjacent the exhaust port, wherein said heater is controlled in response to detection signals from said temperature sensor to keep the exhaust temperature at a constant value, while the vapor emitting from the food in the atmosphere adjacent the exhaust port is detected by the humidity sensor and the time required for relative humidity to reach a predetermined amount of change due to said vapor emitting from the food is calculated by a microcomputer, and said tood is cooked or frozen food is thawed according to one of heating patterns determined according to the kind of food with said time used as a function, enabling automatic cooking of not only foods in general but also frozen foods.
  • Fig. 1 is a perspective view of an automatic microwave oven, showing an embodiment of the present invention
  • Fig. 2 is a front view of the operating section of the same
  • Fig. 3 is a plan view of the heating chamber of the same
  • Fig. 4 is a perspective view of the humidity sensor of the same
  • Fig. 5 is the circuit diagram of the control device of the same
  • Figs. 6 and 7 are graphs showing humidity characteristics when the cooking and thawing of beet are effected.
  • Fig. 1 shows an automatic microwave oven according to an embodiment of the present invention, having an operating section 1 and a door 2, with an exhaust port 3 formed in a top plate at a corner thereot.
  • Fig. 2 is a front view ot the operating section 1.
  • a display section 4 indicates the time.
  • the time can be inputted by a clock switch 5 and numeral keys 6.
  • a high frequency output is selected by a power key 7 and then an optional time is inputted by numeral keys 6, and cooking is started by a start key 8.
  • Keys denoted by 9 and 10 are an automatic cooking key and an automatic thawing key based on humidity, sensor control which is the point of the present invention.
  • a numeral corresponding to the food e.g., A1
  • a canceling key denoted by 11 is a key used to interrupt cooking or cancel the program.
  • Fig. 3 shows a plan view of a heating chamber 12, indicating the path of flow of cooling air.
  • the air from a cooling fan driven by a fan motor 13, after cooling a magnetron 14, is passed across a heater 15 and then through a suction port 16 in the heating chamber 12 to enter the latter, and it is exhausted together with the water vapor emanating from the food (not shown), through an exhaust port 17 in the heating chamber 12 and it is concentrated by an exhaust guide 18, passes a humidity sensor 19 and a temperature sensor 20 and is tinally discharged to the outside through the exhaust port 3 in the top plate of the body.
  • Fig. 4 shows the humidity sensor 19 composed of a refreshing heater 19-a and a detecting element 19-b, having a refreshing function such that the dirt sticking to the surface of the detecting element 19-b is burnt up by elevating the surface temperature to about 500°C by the refreshing heater 19-a so as to maintain constant the humidity characteristic of the detecting element 19-b.
  • Fig. 5 shows the circuit diagram of the automatic microwave oven main body showing an embodiment ot the invention.
  • a power source plug 21 is connected to a low voltage transformer 23 through a fuse 22 to feed power to a control section 24.
  • the input-output relation of the control section 24 is such as to control, by a microcomputer inside the control section 24, the display section 4 for indicating the time when the microwave oven is not used or for indicating the contents of cooking and the remaining time for cooking, a key board 25 tor inputting cooking time, the temperature sensor 20 for detecting the temperature of exhaust air adjacent to the exhaust port 17, the humidity detecting element 19-b for detecting the humidity in the exhaust section, the refreshing heater 19-a for removing dirt from the humidity detecting element 19-b, a power relay 27 for opening and closing the power source to the heater 15 and a high voltage transformer 26, a temperature control relay 28 for on-off controlling the heater 15 in response to signals from the temperature sensor 20 so as to maintain the exhaust temperature at a constant value, a heater changeover relay 29 for changeover between
  • 31, 32 and 33 denote a first latch switch, a second latch switch and a short switch, the role of the short switch 33 being to blow the tuse 22 to cause a fault on the safety side if the door 2 is opened when the first latch switch 31 is in a fused or other abnormal state.
  • the power for the magnetron 14 is supplied by half-wave double-voltage rectification ot high voltage on the secondary side of the high voltage transformer 26 and through the high voltage reed switch 30.
  • a high trequency output and a cooking time are inputted from the key board 25, whereupon the cooking time is indicated on the display section 4, and pushing the start key 8 causes the cooking time on the display section 4 to be counted down, while closing the power relay 27 to energize the high voltage transformer 26.
  • the high voltage reed switch is closed or intermittently or on-off operated according to the high trequency output which is set. In this case, the temperature control relay 28 remains opened, that is, the heater 15 is not energized.
  • the refreshing action is periodically performed by energizing the refreshing heater 19-a.
  • Fig. 6 shows a humidity detection characteristic where automatic cooking is performed.
  • the humidity detecting element 19-b is responsive to relative humidity and exhibits a negative resistance characteristic with respect to temperatures above 150°C, so that it is possible to maintain the refreshing temperature at a constant value by reading the resistance value of the humidity detecting element 19-b during retreshing.
  • the refreshing operation is performed immediately after start, and then a humidity detecting state is established.
  • point a at the time ot start shows the relative humidity of the room, and the exhaust section temperature is read at the same time by the temperature sensor 20. On the basis ot the exhaust section temperature thus read, the exhaust section temperature to be controlled is determined.
  • the need for maintaining the exhaust temperature at a high value arises from the tact that where the atmosphere in the room has a high relative humidity, it cannot further contain the water vapor from the food. That is, it becomes saturated, making it impossible to know the amount of change of humidity.
  • the atmosphere in the chamber is 20"C, 100%, heating it to 50°C by the heater 15 changes the relative humidity to about 20%, enabling the atmosphere to turther contain 70 g/m 3 , so that the humidity sensor 19 can detect water vapor up to 70 g/m 3 generated from the food.
  • exhaust control temperatures are classified into four temperatures, 35°C, 40°C, 50°C, and 55°C, and an optimum temperature is selected therefrom according to the room temperature.
  • Another reason for keeping the exhaust temperature at a high value is to give ample room for humidity detection by keeping the exhaust temperature at a high value in advance since control becomes impossible if the exhaust control temperature is exceeded owing to temperature rises of the food and electric parts from when the heater 15 starts to control the exhaust temperature to a constant value and the minimum value of relative humidity is stored to when a certain tixed amount of change of relative humidity is obtained to detect vapor from the food.
  • the 400 W heater 15-a of greater output included in the heater 15, and the refreshing heater 15-b are energized. Since the refreshing heater 19-a is integrally installed in close vicinity to the humidity detecting element 19-b, the relative humidity of the atmosphere around the humidity detecting element 19-b sharply decreases, reaching point b near 0%. When the atmosphere temperature exceeds 150°C, the humidity detecting element 19-b exhibits a negative resistance characteristic, so that when it is about 500°C, it reaches point c. Thereafter, the refreshing heater 19-a is deenergized and hence the temperature lowers. When the temperature is below 150°C, the atmosphere around the refreshing heater 19-b becomes dried, reaching point d.
  • the relative humidity from point b to point d is shown by'a characteristic represented by a straight line connecting points b and d.
  • the atmosphere around the humidity detecting element 19-b is cooled.
  • the oscillation start point f is reached where the magnetron 14 starts to oscillate and the counting of the time till vapor detection is started. From start point a to oscillation start point f, the continuous energization of the 400 W heater 15-a accelerates arrival at point f.
  • the exhaust temperature is controlled by the temperature control relay 28.
  • the reason for using the 400 W heater 15-b after point f is that the use of the 100 W heater 15-a alone is insufficient to maintain the exhaust temperature.
  • the method of detecting humidity comprises the steps of storing the lowest value of relative humidity which takes plce after point t, counting the time until a predetermined amount of change of relative humidity is obtained, and progressing automatic cooking on the basis of it.
  • the characteristics of humidity change shown in the figure refer to the cooking ot 1 Kg, 2 Kg and 3 Kg of beef, respectively indicated by characteristic curves g, h and i.
  • j indicates an amount of change of relative humidity for determining a reference detection time T 1 which is a function of a heating program, the j changing with the kind of food and exhaust control temperature. This is because the amount of saturated water vapor differs with temperature and because the amount of change which affects relative humidity varies even if the same weight of water evaporates from food.
  • the reference detection time T 1 with respect to the weight of food varies the more clearly and stabilizes the more, the greater the amount of change j of relative humidity, so that it is important that the relative humidity be minimized when cooking is started.
  • a heating program for cooking roast beef using the reference detection time T 1 detected in this way is as follows.
  • the high frequency output is made a medium low output (350 W) and heating is effected for time T 3 .
  • This is a program empirically tound when roast beef is to be medium-finished, but similar procedures may be applied to various menus, and heating patterns, such as the one described above, are stored in the automatic cooking keys 9 according to the kinds of menues.
  • Fig. 7 shows a humidity detection characteristic where thawing of frozen beef is performed. This is the same as the aforesaid automatic cooking up to point f where a predetermined control temperature is reached by using the heater 15, but after point f, in the case ot automatic thawing, the 100 Wheater 15-b is used without employing the 400 W heater 15-a. In the case of automatic thawing, control is performed without using so high a temperature setting with respect to the exhaust temperature detected at the start of cooking.
  • Detection of the lowest value of relative humidity is effected after point k, and when the amount of change reaches point j, the reference detection time T 1 is obtained. After detection, as in the case of automatic cooking, the temperature control relay 28 is opened and control of exhaust temperature is not performed. As is clear from Fig. 7, the amount of change j of humidity which is set is much smaller than in the case of automatic cooking, and, since ripples of exhaust temperature must be minimized, the 400 W heater 15-b, which has a large amount ot overshoot, cannot be used.
  • This procedure can be applied also to the thawing of other frozen foods, and moreover, by combining i with other high frequency outputs as a function of time T,, it is possible to automate all operation from thawing to cooking.
  • the exhaust temperature is made constant by heaters installed adjacent the suction port so as to detect relative humidity, so that accurate amounts of change of humidity can be found, and by utilizing the humidity detection time it is possible to attain automation of cooking, thawing, and trom thawing to cooking ot a variety of foods. Further, since there is no need to use wraps or special containers, there is no danger of spoiling the external appearance and taste of food, nor is the danger of failure in cooking or overheating tood or causing a fire. Thus, a high trequency heating apparatus which is convenient to use can be provided.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Electric Ovens (AREA)
  • Control Of High-Frequency Heating Circuits (AREA)

Abstract

Dispositif de chauffage à haute fréquence permettant d'obtenir une cuisson automatique en combinaison avec un micro-ordinateur et différents détecteurs. Un élément chauffant (15) est disposé à proximité d'un orifice d'aspiration (16) du boîtier d'un corps de chauffe (12), et un détecteur de température (20) et un détecteur d'humidité (19) sont disposés à proximité d'un orifice d'échappement (17). L'élément chauffant (15) est commandé en fonction des signaux de température provenant du détecteur (20), ce qui permet de maintenir constante la température d'échappement, et la vapeur dégagée par les aliments est détectée par le détecteur (19) placé dans la vapeur. Les mesures ne sont pratiquement pas influencées par les conditions ambiantes dans la cuisine, et par conséquent ce dispositif chauffant assure la cuisson automatique d'une gamme plus étendue d'aliments que les dispositifs conventionnels.
EP19820901428 1981-11-06 1982-05-13 Dispositif de chauffage a haute frequence. Withdrawn EP0093172A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP17883381A JPS5880427A (ja) 1981-11-06 1981-11-06 高周波加熱装置
JP178833/81 1981-11-06

Publications (2)

Publication Number Publication Date
EP0093172A1 true EP0093172A1 (fr) 1983-11-09
EP0093172A4 EP0093172A4 (fr) 1984-04-24

Family

ID=16055457

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19820901428 Withdrawn EP0093172A4 (fr) 1981-11-06 1982-05-13 Dispositif de chauffage a haute frequence.

Country Status (3)

Country Link
EP (1) EP0093172A4 (fr)
JP (1) JPS5880427A (fr)
WO (1) WO1983001674A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0198430A2 (fr) * 1985-04-11 1986-10-22 Matsushita Electric Industrial Co., Ltd. Appareil de chauffage à détecteur piézoélectrique

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111638115A (zh) * 2014-05-16 2020-09-08 比奥利弗解决方案公司 用于自动样品解冻的系统、装置和方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2260073A1 (fr) * 1974-02-01 1975-08-29 Dca Food Ind
FR2335799A1 (fr) * 1975-12-19 1977-07-15 Elektromaschinen Ag Four a micro-ondes et a air chaud
EP0000957A1 (fr) * 1977-08-30 1979-03-07 Litton Systems, Inc. Four à micro-ondes à régulation d'humidité et méthode de cuisson
FR2451145A1 (fr) * 1979-03-06 1980-10-03 Sharp Kk Four mixte a chauffage electrique et par micro-ondes
EP0031156A1 (fr) * 1979-12-24 1981-07-01 Matsushita Electric Industrial Co., Ltd. Four de cuisine avec détecteur d'humidité en céramique

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5847611B2 (ja) * 1976-12-01 1983-10-24 松下電器産業株式会社 調理用オ−ブン

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2260073A1 (fr) * 1974-02-01 1975-08-29 Dca Food Ind
FR2335799A1 (fr) * 1975-12-19 1977-07-15 Elektromaschinen Ag Four a micro-ondes et a air chaud
EP0000957A1 (fr) * 1977-08-30 1979-03-07 Litton Systems, Inc. Four à micro-ondes à régulation d'humidité et méthode de cuisson
FR2451145A1 (fr) * 1979-03-06 1980-10-03 Sharp Kk Four mixte a chauffage electrique et par micro-ondes
EP0031156A1 (fr) * 1979-12-24 1981-07-01 Matsushita Electric Industrial Co., Ltd. Four de cuisine avec détecteur d'humidité en céramique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO8301674A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0198430A2 (fr) * 1985-04-11 1986-10-22 Matsushita Electric Industrial Co., Ltd. Appareil de chauffage à détecteur piézoélectrique
EP0198430A3 (en) * 1985-04-11 1988-07-20 Matsushita Electric Industrial Co., Ltd. Heating apparatus with piezoelectric device sensor

Also Published As

Publication number Publication date
EP0093172A4 (fr) 1984-04-24
JPS5880427A (ja) 1983-05-14
WO1983001674A1 (fr) 1983-05-11

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Inventor name: UENO, AKIHIKO

Inventor name: WATANABE, KENJI

Inventor name: AKIYOSHI, MITSUO

Inventor name: WATANABE, KIYOSHIGE