JP5358930B2 - High frequency heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent abnormal heating and a malfunction in manual heating in which a user sets an optional time to operate a heater. <P>SOLUTION: This high-frequency heater includes: a surface temperature detecting means 5 for detecting the temperature of food in a heating chamber 1 in a non-contact state; an oven temperature detecting means 7 for detecting an atmosphere temperature in the heating chamber; and a control part 8 for controlling an output of the high-frequency generation means based on outputs from the surface temperature detecting means and the oven temperature detecting means, wherein the control part lowers the output level of the high-frequency generation means in the case that the temperature of the surface temperature detecting means reaches a predetermined value or higher and the temperature of the oven temperature detecting means reaches a predetermined value or higher when the user sets an optional time and inputs heating start operation. Thus, it is possible to provide the safe and high-reliability high-frequency heater which can prevent abnormal heating in the case of manually heating a small quantity of food, and prevent early cutting in the case of heating the frozen food using a heat generation sheet. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a high-frequency heating apparatus in which food temperature in a heating chamber is detected by a surface temperature detection means and safety is taken into consideration.

In general, high-frequency heating devices such as a microwave oven ensure safety by taking measures against abnormal heating due to misuse by the user. For example, calculate the weight change from the initial stage of the food when the steam generated from the food is detected during high-frequency heating, and compare it with the abnormal heating judgment weight calculated from the time until the steam is detected. An apparatus is disclosed that is terminated to prevent abnormal heating of food (see, for example, Patent Document 1).
JP 2003-214632 A

  The conventional high-frequency heating device needs to measure the weight of food, and the weight of the food is measured through a mounting table on which the food is placed. In this case, if the mounting table is circular, weight measuring means can be provided under the shaft supporting the mounting table, but food cannot be placed outside the circular mounting table in the rectangular heating chamber. Since space is created, the amount of food that can be cooked at one time is the area of the mounting table, and the area of the bottom surface of the heating chamber cannot be used effectively. Therefore, high-frequency heating devices such as microwave ovens in recent years also have a meaning of improving the cleaning property, and the configuration in which the bottom surface of the heating chamber is formed in a flat shape has been mainly used. In the apparatus, the bottom surface of the heating chamber is fixed to the heating chamber, and it is difficult to provide weight measuring means. Even if it can be configured, the number of parts increases and the product becomes expensive.

  For this reason, many recent high-frequency heating apparatuses are equipped with an infrared sensor that detects the surface temperature of food instead of weighing. And in this heating apparatus, if the surface temperature of the foodstuff which an infrared sensor detects reaches predetermined temperature, it will judge that it is abnormal and will stop heating. Since this infrared sensor detects the surface temperature of food, automatic heating can be performed to automatically stop heating when the food reaches an appropriate temperature based on the output of the infrared sensor.

  However, in the case of manual heating in which the user sets and operates at an arbitrary time, heating to an appropriate temperature depends on the heating power selected by the user and the set time. That is, referring to the user's experience, information described in the instruction manual, etc., the heating power and the heating time are set according to the size and type of food to operate. Therefore, the heating device operates regardless of whether the selected heating power and heating time are appropriate, and there is concern that the food may be abnormally heated if the selected heating conditions are not appropriate.

  Therefore, the present inventor utilizes the infrared sensor even during the manual heating, and is configured to reduce the heating power when the infrared sensor detects an abnormally high temperature, thereby improving safety. However, in recent years, among the frozen foods on the market, foodstuffs for microwave ovens characterized by scorching using a heat generating sheet heated at high frequency have been released, and simply detecting high temperatures It was found that when the heating power is reduced, the infrared sensor detects the high temperature of the heat generating sheet portion, and the frozen food is not sufficiently heated and the operation stops while it is cold.

The present invention solves such a problem, and the heating power and the heating time set by the user are not appropriate in view of the amount of food, and even when abnormal heating occurs, the temperature in the heating chamber is detected. It is an object of the present invention to provide a high-frequency heating device that can be operated safely and that prevents premature breakage even for commercially available frozen foods that use a heat-generating sheet.

In order to solve the above-described conventional problems, a high-frequency heating device according to the present invention includes a surface temperature detection unit that is disposed outside a wall surface of a heating chamber and detects the temperature of food in the heating chamber in a non-contact manner, and an atmosphere in the heating chamber. An internal temperature detecting means for detecting the temperature, and a control section for controlling the output of the high frequency generating means based on the outputs from the surface temperature detecting means and the internal temperature detecting means. When an arbitrary time is set and a heating start operation is input, the temperature of the surface temperature detecting means is equal to or higher than a predetermined value, and the detected temperature of the internal temperature detecting means at the time of starting heating and at that time When the temperature difference from the temperature detected by the internal temperature detecting means becomes a predetermined value or more, the output level of the high-frequency generating means is lowered, and the surface temperature detecting means has a predetermined time set by the user for a predetermined time. Set longer than value It is performed reciprocated for surface temperature detected only if, in the case of less than the predetermined value is a structure that does not perform the reciprocating operation for surface temperature detection.

  With the above configuration, when the user heats a small amount of food, even if the heating power is mistakenly increased and the heating time is set to be long and the heating is started, an increase in the atmospheric temperature in the heating chamber is detected and heating is performed. If it is determined that the temperature of the food in the room has become high, the heating power is reduced so that the heating does not proceed further, so that abnormal heating of the food can be prevented. In addition, when heating frozen food using a heat generating sheet, the heat generating sheet becomes high temperature after the start of heating, but heating power is not reduced until an increase in the atmospheric temperature in the heating chamber is detected. There is no longer a situation where the heating is finished while it is cut and frozen.

  According to the present invention, abnormal heating when manually heating a small amount of food can be prevented, and premature cutting when heating frozen food using a heating sheet can be prevented, and safe and reliable high-frequency heating. Equipment can be provided.

1st invention is arrange | positioned in the heating chamber which accommodates a foodstuff, the high frequency generation means which heats the foodstuff in the said heating chamber by a high frequency, and the wall surface outer side of the said heating chamber, The surface temperature of the foodstuff in a heating chamber is contactless Control for controlling the output of the high-frequency generating means based on the output from the surface temperature detecting means for detecting, the internal temperature detecting means for detecting the atmospheric temperature in the heating chamber, and the surface temperature detecting means and the internal temperature detecting means and a section, wherein, if a user inputs a heating start operation by setting an arbitrary time, the detected temperature of the surface temperature detecting means is equal to or greater than the predetermined value, and, in the heating start time When the temperature difference between the detected temperature of the internal temperature detecting means and the detected temperature of the internal temperature detecting means at that time is equal to or greater than a predetermined value, the output level of the high frequency generating means is reduced and used. Person When heating a small amount of food, even if the heating power is mistakenly increased and the heating time is set longer, even if the heating is started, an increase in the atmospheric temperature in the heating chamber is detected, and the food temperature in the heating chamber becomes high. If it is judged that it became, since heating power is reduced so that heating does not advance any more, abnormal heating of food can be prevented. In addition, when heating frozen food using a heat generating sheet, the heat generating sheet becomes high temperature after the start of heating, but heating power is not reduced until an increase in the atmospheric temperature in the heating chamber is detected. There is no longer a situation where the heating is finished while it is cut and frozen. Further, the surface temperature detecting means performs a reciprocating operation for detecting the surface temperature only when an arbitrary time set by the user is set longer than a predetermined value. Therefore, it is possible to reduce the number of times of driving and ensure the durability of the driving components.

In particular, the second invention is the high-frequency heating device of the first invention, wherein the surface temperature detecting means is reciprocated between predetermined angles so as to detect a temperature within a predetermined range in the heating chamber. is there. The reciprocating operation makes it possible to detect the temperature of the entire heating chamber, so that the temperature of the food can be detected regardless of where the user puts the food, and abnormal heating of the food can be reliably prevented. Become.

  According to a third aspect of the present invention, in the high-frequency heating device of the second aspect, the temperature is detected by reciprocating operation at regular time intervals at the beginning of heating, and when the temperature of the surface temperature detecting means becomes a predetermined value or more, The operation is switched from a constant time interval to a continuous operation. Considering the fact that the temperature of food is unlikely to rise abnormally at the beginning of heating, it is not necessary to detect the temperature continuously. On the other hand, the temperature of the food rises after a certain amount of time has passed. Then, in some cases, there is a possibility of abnormal heating. For this reason, when a certain amount of heating time elapses and the food is abnormally heated, the temperature of the food is continuously detected and constantly monitored so as not to cause abnormal heating of the food. As a result, it is possible to reduce the number of times the temperature detection device is driven, so that it is possible to ensure the durability of the driving components and reduce the contamination of the lens during driving.

According to a fourth aspect of the present invention, in the high-frequency heating device of the third aspect, the control unit has a plurality of thresholds for lowering the output level of the high-frequency generating means, and the detected temperature of the internal temperature detecting means at the heating start time and the time point The threshold value is selectively used according to the time until the temperature difference from the temperature detected by the internal temperature detection means exceeds a predetermined value. Vapor generation time varies depending on the size of the food. Because small foods generate steam quickly, the ambient temperature in the heating chamber rises quickly. On the other hand, the surface temperature detection for acquiring the temperature of the food is acquired as an average value of the projected area from the sensor, so there is no problem when the food is large, but when the food is small, the average of the food and the surrounding temperature is obtained. So get lower than the actual temperature. Therefore, if the size of the food is estimated based on the time when the atmospheric temperature of the heating chamber rises, and the threshold for lowering the output level is set separately for small loads and large quantities, abnormal heating can be achieved even when heating with small loads. Can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
1 is a system schematic diagram of a high-frequency heating device according to Embodiment 1 of the present invention, FIG. 2 is a front view showing a state where an opening / closing door of the high-frequency heating device is opened, and FIG. 3 is a configuration diagram of a machine room as viewed from the right side. 4 is a block diagram showing the electrical configuration, and FIG. 5 is a flowchart for explaining the operation.

On the bottom surface of the heating chamber 1 is inserted a salauque die 2 obtained by cutting the crystallized glass serving as the bottom surface of the heating chamber with the dimensions of the heating chamber. A temperature detection hole 4 is formed above the right side surface of the heating chamber, and surface temperature detecting means 5 (hereinafter referred to as an infrared sensor 5) disposed outside the wall surface of the heating chamber is disposed opposite to the heating chamber. The surface temperature of the food 3 in the chamber 1 is detected without contact. The infrared sensor 5 is repeatedly operated in the direction indicated by the arrow by the drive motor 6 so that the temperature in a predetermined range of the bottom surface portion in the heating chamber 1 can be detected. Inside the top right of the top surface of the heating chamber, a chamber temperature detecting means (hereinafter referred to as a heating chamber thermistor 7) for measuring the atmospheric temperature in the heating chamber is provided. Reference numeral 8 denotes a control unit mainly composed of a microcomputer for controlling the operation of the drive motor 6 and A / D converting the signal voltage obtained from the surface temperature detecting means 5 and the signal voltage obtained from the thermistor 7 for the heating chamber. The A / D converted surface temperature data of the food 3 is compared with the judgment value of the finished surface temperature of the predetermined food 3 to determine the heating time of the food 3 or to control the output of the high frequency generating means described later. Is. In the back of the heating chamber 1, there is disposed a water reservoir 10 for boiling the water supplied from the nozzle 9 to generate steam.

A door 11 is provided on the front surface of the heating chamber 1 so as to be openable and closable. Furthermore, various operation keys 11a to 11d for a user to select a heating menu, an instruction to start heating, and a display unit 12 for performing necessary display are provided. An operation panel 13 is provided. A control board (not shown) is disposed on the back side of the operation panel 14, and a control circuit 8 and a drive circuit 15 for operating the high frequency generating means are provided on the control board. A machine room is provided behind the operation panel.

  In the machine room, a magnetron 15 serving as a high-frequency generating means is disposed on the right side wall of the heating chamber 1. A cooling fan 17 and an air guide A18 attached to the writer 16 are disposed on the right side of the magnetron 15 to cool the magnetron 15. An air guide C <b> 19 is installed on the left side of the magnetron 15 to send air into the heating chamber 1. The air guide C19 is provided with an exhaust thermistor 20 that detects the temperature of the magnetron 15. The high frequency oscillated from the magnetron 15 supplies microwaves into the heating chamber 1 from a power supply port (not shown) provided on the bottom surface of the main body via a waveguide (not shown). An inverter 21 that varies the output of the magnetron 15 is disposed above the magnetron 15. The infrared sensor 5 is arranged between the inverter 21 and the lamp 22 that illuminates the inside of the heating chamber 1.

  FIG. 4 shows the electrical configuration. In FIG. 4, the control unit 8 includes various operation keys 11 a to 11 d including a start switch, an infrared sensor 5, an exhaust thermistor 20 that detects the temperature of the magnetron 15, and a heating chamber that detects the temperature in the heating chamber 1. A signal from the thermistor 7 is input. The control unit 8 displays information on the heating time and accessories on the display 12 according to a program stored in advance based on these signals, and via the drive circuit 15, the magnetron 15, the upper heater 22, the lower heater 23, the cooling The fan 16, the steam heater 24, and the drive motor 6 are controlled. Since the magnetron 15 is controlled via the inverter 21, the output can be controlled. For example, the steam heater 24 and the high frequency output 300W can be used simultaneously.

  The operation of the high-frequency heating apparatus configured as described above will be described with reference to the flowchart of FIG.

  In the flowchart of FIG. 5, the part related to the gist of the present invention is shown in the control contents by the control unit 8, and this will be described below together with related actions.

  When the user heats food, the output power of the high frequency heating is selected by tapping the “range output switching” key of the operation key 11b (step S1). The high-frequency heating device of the present embodiment is set so that 800 W output is selected when it is first pressed, and is switched from 600 W to 500 W to 150 W every time it is tapped. Here, it is assumed that 800 W output is selected. Next, the user sets the time to be operated by turning the dial of the operation key 11c (step S2). The maximum heating time is 10 minutes when the user selects 800W as the output power for high frequency heating. When 600 W and 500 W are selected, the maximum heating time is set to 30 minutes, and when 150 W is selected, it is set to be selectable up to 5 hours. Next, the user presses a “start” key for instructing the start of heating, and heating and heating starts (step S3). The drive motor 6 is operated simultaneously with the start of heating and heating.

  During heating, the controller 8 first monitors whether the door 11 has been opened as a determination of whether to stop heating (step S4). When the door 11 remains closed, it is monitored whether or not the “cancel” key of the operation key 11d is pressed (step S5). Even if the heating operation time set by the user has not been reached, the heating can be stopped at an arbitrary time by opening the door 11 or pressing the “cancel” key (step S8). ).

  Conventionally, in the case of manual heating, when the door 11 is closed and there is no “cancel” key operation, the control unit 8 monitors whether or not the heating time set by the user has been reached. (Step S7).

In the present invention, after step S5, first, determination of the temperature of the heating chamber thermistor 7 is added (step S6). In step S6, it is determined whether the temperature in the heating chamber has increased by T ° C. After the start of heating, the temperature in the heating chamber is maintained at the starting temperature for a while. As heating progresses, steam begins to be generated from the food and the temperature in the heating chamber also rises. The determination value T ° C. for determining whether the food is sufficiently heated was set to 10 ° C. by experiment. When it does not exceed 10 ° C. in step S6, it is determined that the heating is not abnormal, and the process proceeds to step S7. When it becomes 10 degreeC or more by step S6, since there exists a possibility of abnormal heating, it is determined whether the surface temperature of a foodstuff has exceeded the predetermined value.

In the present embodiment, the predetermined value of the surface temperature of the food is set so as to be distinguishable depending on the size of the food. When the temperature rise in the heating chamber becomes 10 ° C. or higher in step 6, the time from the start of heating until the temperature of the heating chamber becomes 10 ° C. or higher is measured, and it is determined whether it is less than the preset X time. (Step S9). When the food is small, the time for steam generation is fast and the temperature rise in the heating chamber occurs in a short time. On the other hand, when the food is large, the temperature rise time in the heating chamber is also delayed. In the present embodiment, the time X for determining the size of the food is set to 2 minutes. When the time to reach Step S9 is 2 minutes or less, it is compared with the threshold value 1 set for the small load for determining whether the food is abnormally heated (Step S10). Here, if the temperature of the threshold value 1 has not been reached, it means that it is not yet in an abnormal heating state, so that the process proceeds to step S7, and heating is continued if there is a remaining heating time. If the threshold value 1 has been reached, it is determined that an abnormal heating state has occurred, and the output is changed (reduced) to heating power 1 (step 11). If the time reaching Step S9 exceeds 2 minutes, comparison is made with the threshold value 2 set for a large load (Step S12). As in the case of a small amount of load, when the threshold value 2 is exceeded, it is determined that an abnormal heating state has occurred, and the process proceeds to step 11. In the present invention, the threshold value 1 is set to 105 ° C., the threshold value 2 is set to 115 ° C., and the heating power 1 is set to 300 W.

FIG. 6 shows a reading range of the infrared sensor 5 of the present embodiment. The infrared sensor 5 has eight elements and is reciprocated by the drive motor 6 so as to detect the entire heating chamber, so that a detection area as shown in the figure is obtained. When the potato-sized 3a is placed in the center of the heating chamber, the food is larger than the detection area, so that the surface temperature of the food itself can be detected. When the remaining food, for example, an object 3b having a size such as a 50g piece of sweet potato, is placed on the left side of the heating chamber, food partially enters the detection area as shown in the figure. The average temperature is acquired together with the portion, and the surface temperature of the complete food is not acquired, but a temperature lower than the surface temperature of the food is detected.

Specifically, a case where one potato is heated will be described. Normally, heating can be performed appropriately by heating at 600 W for 4 minutes, but it is assumed that the user sets 800 W for 10 minutes. After the start of heating, it took 2 minutes and 30 seconds for the atmospheric temperature of the heating chamber to rise by 10 ° C. At this time, the detected surface temperature of the food was 95 ° C. Since 115 ° C. of threshold value 2 has not been reached, the heating power of 800 W is continued. Thereafter, as the heating continued, the food surface temperature rose and reached 115 ° C. in 6 minutes and 50 seconds. At this point, the heating power is lowered to 300 W and heating is continued. Since the heating power was reduced, the increase in the surface temperature of the food was suppressed, and when the set 10 minutes had passed, it reached 119 ° C., but there was no abnormal heating of potatoes.

Next, the case where a frozen pizza is heated is demonstrated. Among commercially available frozen pizzas, there is a type in which a sheet that generates heat at a high frequency is laid on the bottom of the food and the bottom is burnt. If it is a frozen pizza with a diameter of about 15 cm, it is written on the packaging bag at 600 W in 2 minutes to 2 minutes and 30 seconds. Depending on the radio wave distribution of the high-frequency heating device, there are many cases where heating is not enough for the time recommended by the food manufacturer, and in the experiment at the examination stage, it was set to 3 minutes 30 seconds and the situation was observed. When heating was started, the detected surface temperature of the food became 120 ° C. at the start of 20 seconds, the heating power dropped to 300 W, and when the heating was stopped, a cold part remained. Although the frozen pizza is circular, the heating sheet is quadrangular, so the four corners of the heating sheet are visible, and the infrared sensor 5 acquires the temperature. At the examination stage, power was reduced by high temperature detection. However, there is a problem with foods such as those with a heating sheet, but in the present invention, the increase in the internal temperature is added to the judgment, so this problem can be solved. . That is, when the frozen pizza is heated again with the product of the present invention, at 3 minutes and 30 seconds, the rise in the internal temperature is 7 ° C., and does not shift to the food surface temperature determination step after step 9, and the heating power is increased. Since the reduction did not occur, the frozen pizza could be heated without problems.

In the present embodiment, the determination in step S6 is performed every 20 seconds at the start of heating, and is continuously acquired when the temperature in the heating chamber rises by 10 ° C. or more and shifts to step S9. In the case of the automatic heating menu that detects the surface temperature of the food and stops heating, the surface temperature of the food is always monitored, but in the case of manual heating where the user sets the heating time and operates, Since it is only necessary to determine whether or not the temperature detection is in an abnormal state, the frequency of the temperature detection is reduced to 1/5 and the durability of the driving device is also considered in comparison with the case of the automatic heating menu. If the infrared sensor is driven when food is heated, the lens surface of the infrared sensor may be contaminated due to the scattering of food caused by the heated food being repelled. Considered.

Moreover, in this Embodiment, it set so that the reciprocation operation | movement for the surface temperature detection of food might be performed only when a user's heating time setting was set longer than 3 minutes. Usually, food does not reach abnormal heating by heating in a short time. In the case of warming drinks or reheating foods, it will be heated enough in 3 minutes or less, so there is no need to perform a reciprocating operation for detecting abnormalities in the range of general use. It has a structure that takes into account the nature.

  As described above, even when the user sets heating power and heating time by mistake and starts heating, the temperature rise in the heating chamber and higher temperature than when normal food is heated can be detected. Thus, by reducing the output power of the high-frequency output while preventing malfunction, abnormal heating of the food can be prevented and it can be used safely.

  As described above, according to the high-frequency heating device according to the present invention, even when a user starts heating with a large heating power for a small amount of food and a long heating time, abnormal heating can be prevented, It is possible to prevent premature breakage when heating frozen food using a heating sheet, and to provide a safe and reliable high-frequency heating device.

1 is a system schematic diagram of a high-frequency heating device according to an embodiment of the present invention. Front view showing a state where the open / close door of the high-frequency heating device is opened Configuration diagram of the machine room viewed from the right side of the high-frequency heating device Block diagram showing the electrical configuration of the control unit Flow chart showing control contents of the control unit Explanatory drawing which shows the temperature acquisition area of the infrared sensor in the same high frequency heating device

1 Heating chamber 5 Surface temperature detection means (infrared sensor)
6 Drive motor 7 Chamber temperature detection means (heating chamber thermistor)
8 Controller 15 High-frequency generator (magnetron)

Claims (4)

A heating chamber for accommodating food, a high frequency generating means for heating the food product of the heating chamber by high frequency, are arranged on the wall outside of said heating chamber, a surface temperature detecting means for detecting the surface temperature of the food in the heating chamber in a non-contact And an internal temperature detection means for detecting the atmospheric temperature in the heating chamber, and a control unit for controlling the output of the high frequency generation means based on outputs from the surface temperature detection means and the internal temperature detection means,
When the user inputs a heating start operation with an arbitrary time set by the user, the detected temperature of the surface temperature detecting means is equal to or higher than a predetermined value, and the internal temperature detection at the time of starting heating is performed. When the temperature difference between the detected temperature of the means and the detected temperature of the internal temperature detecting means at that time is a predetermined value or more, the output level of the high frequency generating means is reduced,
The surface temperature detecting means performs a reciprocating operation for detecting the surface temperature only when an arbitrary time set by the user is set longer than a predetermined value. A high-frequency heating apparatus characterized by not reciprocating. 2. The high frequency heating apparatus according to claim 1, wherein the surface temperature detecting means is reciprocated between angles set in advance so as to detect a temperature within a predetermined range in the heating chamber. The temperature detection by the reciprocating operation of the surface temperature detecting means is performed at regular time intervals at the beginning of heating, and if the temperature output from the surface temperature detecting means exceeds a predetermined value, the reciprocating operation is changed from a constant time interval to continuous operation. The high-frequency heating device according to claim 2, wherein the high-frequency heating device is switched. The control unit has a plurality of threshold values for lowering the output level of the high frequency generating means, and a temperature difference between the temperature detected by the internal temperature detecting means at the start of heating and the temperature detected by the internal temperature detecting means at that time The high-frequency heating device according to claim 3, wherein the threshold value is selectively used depending on a time until the predetermined value is exceeded.