JPH02140514A - High frequency heater device - Google Patents

Abstract

PURPOSE:To shorten a waiting time until a defreezing cooking is started by a method wherein in case that a temperature within a heating chamber exceeds a predetermined temperature of defreezing processing, a forced cooling by a fan device is carried out and a high frequency wave generating device is energized after a predetermined time elapses. CONSTITUTION:Before taking out a frozen food from a freezing chamber, a defreezing key switch 14 is operated. Then, a micro-computer 27 may judge whether a temperature T within a heating chamber exceeds a predetermined temperature (t0) by a temperature sensor or not. When exceeded, it is judged as the state in which a cooking may not be performed, a fan motor 9a is energized, a fan device blows air into the heating chamber and then a forced cooling is carried out within the heating chamber 5. When it is judged as a relation of t0>=T through the forced cooling within the heating chamber, the micro-computer 27 may terminate a fan device, and ring a buzzer 30. When the start key switch 14 is operated, a control circuit 26 is driven in such a way as a relay coil 28 may be energized and the cooking can be performed. Then, the frozen food is taken out of a freezing chamber of a refrigerator, stored within the heating chamber and then the start key switch 14 is operated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a high-frequency heating device, and particularly relates to an improvement in heating control related to the temperature inside a heating chamber when thawing frozen foods. be.

(Prior art) In high-frequency heating devices such as microwave ovens, when thawing frozen food such as sashimi or meat after long-time cooking, the temperature inside the heating chamber becomes considerably high. Therefore, if the magnetron is oscillated and frozen food is heated using high-frequency waves, the surface of the sashimi and meat will come into contact with the high-temperature air and end up being undercooked. To avoid this, conventional microwave ovens are equipped with a temperature sensor that detects the temperature inside the heating chamber, and if the temperature detected by this temperature sensor exceeds a predetermined temperature (for example, 60 degrees Celsius), an error message is displayed. Even if a key operation to select defrosting cooking is performed, the key operation is not accepted. Therefore, if an error message is displayed, the user must store the frozen food in the freezing chamber again, wait until the temperature in the heating chamber falls below the predetermined temperature, and then put the frozen food back into the heating chamber to defrost it. I was trying to do that.

(Problems to be Solved by the Invention) However, in conventional microwave ovens, cooling inside the heating chamber relied on natural cooling, so there was a problem in that it was necessary to wait a long time until the state was ready for defrosting and cooking.

The present invention has been made in view of the above circumstances, and its purpose is to provide a high-frequency heating device that can thaw and cook frozen foods in a relatively short time even when the temperature inside the heating chamber is high. There is something to do.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the high frequency heating device of the present invention supplies high frequency waves emitted from a high frequency generator into a heating chamber to heat the object to be heated. A device that heats a heating chamber is provided with a temperature sensor that detects the temperature inside the heating chamber, and a fan device that blows air into the heating chamber to forcibly cool the heating chamber,
When thawing and cooking of frozen food is selected, if the temperature detected by the temperature sensor exceeds a predetermined temperature, the fan device is operated for forced cooling in the heating chamber, and the high-frequency generator can be energized at a predetermined time. A control means is provided to enable the state.

In this case, it is preferable to provide a notification device that performs a notification operation when the control device makes cooking possible.

In addition, a temperature sensor for detecting the temperature inside the heating chamber, a fan device for blowing air into the heating chamber to forcibly cool the heating chamber, and a cooking time setting means for setting the thawing cooking time of the frozen food are provided. Thaw food W! When the J principle is selected, on the condition that the temperature detected by the temperature sensor exceeds a predetermined temperature, the fan device is operated for forced cooling in the heating chamber, and from a predetermined time the high-frequency generator starts high-frequency heating of frozen foods. It is also possible to provide a control means for executing the cooking for a time corresponding to the thawing cooking time set by the cooking time setting means.

In this case, the heating of the frozen food by the high frequency generator corresponds to the difference between the thawing cooking time set by the cooking time setting means and the time required to cool the inside of the heating chamber to a predetermined temperature or less by operating the fan device. It is better to run it for a certain amount of time.

Further, it is preferable that the output level of the high frequency generator is changed depending on the initial temperature in the heating chamber or as the time FJO progresses.

(Operation) According to the invention described in claim 1, thawing: J! When an operation is performed to perform the J process, the temperature inside the heating chamber is first detected by the temperature sensor, and if the detected temperature exceeds a predetermined temperature, the fan device is operated. Through this operation, the inside of the heating chamber is forcibly cooled, and the inside of the heating chamber is quickly cooled down. Then, at a predetermined time, for example, when a predetermined period of time has elapsed after the fan device started blowing air, or when the temperature inside the heating chamber has fallen below a predetermined temperature, the high-frequency generator is enabled to be energized.

When the temperature detected by the h1 temperature sensor is below a predetermined temperature, the high frequency generator can be energized immediately without forced cooling by the fan device. When the high-frequency generator becomes energized, the user can properly know that the state is ready for thawing and cooking by making a notification means such as a buzzer sound as in the invention as claimed in claim 2. Can be done.

Thereafter, the user takes out the frozen food from the freezer compartment of the refrigerator, stores it in the heating chamber, and starts defrosting and cooking.

Further, according to the third aspect of the invention, the frozen food taken out from the freezing compartment of the refrigerator is stored in the heating chamber, and the operation for thawing and cooking is performed. Then, the temperature inside the heating chamber is first detected by the temperature sensor, and if the detected temperature exceeds a predetermined temperature, the fan device is operated. Through this operation, the inside of the heating chamber is forcibly cooled, and the inside of the heating chamber is quickly cooled down. Then, at a predetermined time, for example, after a predetermined period of time has elapsed since the fan device has started blowing air, or when the temperature inside the heating chamber has fallen below a predetermined temperature, the high-frequency heating by the high-frequency generator starts at the thawing cooking time set by the cooking time setting means. It will run for a certain amount of time.

At this time, the frozen food is heated by the high temperature air in the heating chamber even during forced cooling operation by the fan device.
According to the invention as claimed in claim 4, the heating by the high-frequency generator is performed for a time corresponding to the difference between the set thawing cooking time and the fan operating time until the temperature in the heating chamber becomes below a predetermined temperature °C. If the food can be eaten at the initial temperature in the heating chamber as in the fifth aspect of the invention, overheating can be prevented. Furthermore, in order to uniformly thaw the frozen food, it is preferable to change the output of the high frequency generator over time as in the sixth aspect of the invention.

(Example) An example in which the present invention is applied to a microwave oven will be described below with reference to the drawings.

1 to 6 show a first embodiment of the present invention. First, the overall structure of the microwave oven is as shown in FIG. M4 and FIG. The interior of the inner box 3 is a heating chamber 5 that is opened and closed by a door 4. A turntable 6 is provided at the bottom of the heating chamber 5, and a temperature sensor 7, such as a thermistor, for detecting the temperature inside the heating chamber 5 is provided at the inner side surface.

Inside the heating chamber 5, a magnetron 8 serving as a high frequency generator is provided between the outer box 2 and the inner box 3 in the main body 1.
The high frequency waves emitted from the

A fan device 9 is provided between the outer box 2 and the inner box 3 inside the main body 1, and this fan device 9 sucks in outside air and blows it against the magnetron 8. After being blown against the magnetron 8, the wind is supplied into the heating chamber 5 through a duct 10, and then exhausted to the outside through an exhaust port (not shown). Also,
The heating chamber 5 is also heated by an electric oven heater 11, and 12 is a convection fan that is driven when the heater 11 cooks in the oven. On the other hand, a panel section 13 at the front of the main body 1 is provided with a key switch group 14 and a display 15. As shown in FIG. 6, the key switch group 14 includes a thawing key switch 14a and a start key switch 14b for defrosting frozen foods.

The main electric circuit configuration of the microwave oven configured as described above is as shown in FIG. 18.19 and Fuse 20
It is connected to the commercial power supply 21 via. Further, a monitor switch 22 that is closed when the door 4 is opened is connected between the door switches 18 and 19 connected to one bus bar of the commercial power source 21 and the other bus bar of the commercial power source 21.

Further, a relay switch 23 and a fan motor 9a of the fan device 9 are connected in series between the two door switches 18 and 19 and the other bus bar of the commercial power source 21. On the other hand, a voltage doubler rectifier circuit consisting of a high voltage capacitor 24 and a high voltage rectifier 25 is configured on the secondary winding 16b side of the high voltage transformer 16, and its DC output is transmitted to the magnetron 8.
It is designed to be applied between the anode and cathode.

Note that the anode of the magnetron 8 is grounded, and the heater is connected to the heater winding 24c of the high voltage transformer 24.

-Next, a control circuit 2 for controlling the entire microwave oven according to this embodiment.
I will explain about 6. This is configured with a microcomputer 27, which receives signals from the key switch group 14 and the temperature sensor 7, displays a required display on the display 15, and operates the relay switches 17 and 23 to open and close them. The relay coils 28 and 29 are energized, and when necessary, a so-called electronic buzzer 3 is used as a notification means.
Drive 0. When the user selects and operates the key switch and then operates the start key switch 14b in order to heat rice, milk, etc., for example, the relay coil 28 is energized and the magnetron 8 is in an oscillating state, causing the temperature inside the heating chamber 5 to rise. A heating process in which the food to be cooked is irradiated with high frequency waves is performed for a set time. At the same time, the relay coil 29 is also energized to cool the magnetron 8. Note that when the start key switch 14b is operated to start cooking, an internal light is turned on in the heating chamber 5, and the turntable 6 is rotated by a motor (not shown).

Among these types of cooking, so-called automatic cooking such as defrosting and cooking of frozen foods is controlled by a microcomputer 27 as a control means according to a program stored in a memory.

Next, in the above configuration, the operation when thawing cooking is selected will be explained with reference to the flowchart of FIG. 1 and the time chart of FIG. 2. From this explanation of the operation, the contents of control by the microcomputer 27 of the control circuit 26 should become more specific.

First, the user operates the thawing key switch 14a before taking out the frozen food from the freezer compartment of the refrigerator.

Then, the microcomputer 27 first determines that the temperature T inside the heating chamber 5 detected by the temperature sensor 7 is a predetermined temperature t.
. For example, it is determined whether the temperature exceeds 60° C. (step a in FIG. 1). For example, immediately after performing oven cooking. If T, the microcomputer 27 sets the state in which the relay coil 28 is not energized even if the start key switch 14b is operated (:J3 impossible state) (step b). Next, the control circuit 26 is driven to energize the relay coil 29 (step C), and the temperature of the heating chamber 5 is displayed on the display 15 (step d). As a result, the fan motor 9a is energized even though the magnetron 8 is not energized, and the fan device 9 starts blowing air into the heating chamber 5 to forcibly cool the inside of the heating chamber 5. The memory of the microcomputer 27 normally stores the temperature inside the heating chamber 5 and the time required to cool it down to the predetermined temperature 1o by forced cooling of the fan device 9 as data. From the contents, the required cooling time corresponding to the current temperature in the heating chamber 5 is read out and displayed on the display 15 (step e). When it is determined that t0≧T due to forced cooling in the heating chamber 5 (step f), the micro combinator 27 switches the relay coil 29
The fan device 9 is stopped by cutting off the power, and the buzzer 30 is activated to notify.

That is, the control circuit 26 is driven to perform a ringing operation (step g), and when the start key switch 14b is operated, the control circuit 26 can be driven to energize the relay coil 28 (cooking ready state). (
Step h). The user then learns from the sound of the buzzer 30 that the temperature in the heating chamber 5 has fallen to a temperature at which thawing and cooking can be performed, takes out the frozen food from the freezer compartment of the refrigerator, stores it in the heating chamber 5, and then starts the operation. key switch 14b. As a result, the relay coil 28 is energized, the magnetron 8 enters an oscillating state, and high frequency waves are supplied into the heating chamber 5 . Thawing cooking of the frozen food is started in the above manner, and after a predetermined period of time has elapsed, the relay coil 28 is cut off, the oscillation of the magnetron 8 is stopped, and the thawing cooking is completed (see FIG. 2 above).

Further, in step a, if to≧T, the microcomputer 27 immediately sounds the buzzer 30 without operating the fan device 9 to notify that defrosting and cooking may be performed immediately. In this case, the user can immediately start defrosting and cooking using the same operation as described above.

Note that the thawing cooking time may be set to a time corresponding to the fn amount by detecting the weight of the frozen food as in the second embodiment described later.

As described above, according to this embodiment, if the temperature in the heating chamber 5 exceeds a temperature suitable for defrosting cooking, such as immediately after oven cooking, the fan device 9 moves into the heating chamber 5. Since the heating chamber 5 is forcibly cooled by blowing air, wasteful waiting time can be shortened and thawing cooking can be started earlier than in the conventional method where the heating chamber has to be cooled down by natural cooling.

Moreover, since the buzzer 30 can notify that the inside of the heating chamber 5 has cooled down, the user can immediately start defrosting and cooking without forgetting.

In the above embodiment, when the temperature detected by the temperature sensor 7 becomes equal to or lower than the predetermined temperature t0, the fan installation rI! Although the operation of the fan device 9 is stopped in the above example, the timing may be determined based on the passage of time from the start of the operation of the fan device 9. Also,
The notification means is not limited to the buzzer 30, but may also be a lamp or the like.

7 to 10 show a second embodiment of the present invention, and the same parts as in the first embodiment are given the same reference numerals, and only different parts will be explained.

In FIG. 9, the control circuit 26 includes a Tfrf for detecting the iim of the frozen food placed on the turntable 6.
A signal from the fi sensor 31 is input. This ff1f
The il sensor 31 is of a capacitance type, and is elastically supported by a spring or the like. Since the amount of descent of the turntable 6 changes depending on the ff1flt of the frozen food, it is a movable electrode that moves in conjunction with the vertical movement of the turntable 6. The weight of the frozen food is detected by the change in capacitance based on the change in the distance between the electrode and the fixed electrode. The microcomputer 27 as a control means is configured to set the thawing cooking time according to the following equation in accordance with the amount of ffi of the frozen food detected by the 111ffi sensor 31.

Thawing cooking time T -0,8W+80 (however, W-O~50
Og) Thawing cooking time T -0,3W + 220 (However, W
-500 to 10100O In addition, W is the weight ffi (g) of the frozen food.

Therefore, the microcomputer 27 also functions as a cooking time setting means for setting the defrosting and cooking time.

Further, the microcomputer 27 is configured to change the output of the magnetron 8 during thawing cooking according to a program stored in the memory, and specifically to reduce the output in stages as the cooking time progresses. The output of the magnetron 8 is set to vary stepwise as an average output by changing the on-duty ratio of the relay switch 17 (relay coil 28). Furthermore, the microcomputer 27 has two FIi types of stepwise output reduction modes for the magnetron 8, a mode shown by a solid line A and a mode shown by a broken line B in FIG. Whether to control the output is determined by the temperature in the heating chamber 5 at the start of thawing cooking, so-called initial temperature. Specifically, if the initial temperature exceeds 200°C, the output is set to the low output side. B mode is selected, and when the temperature is below 200°C, A mode lower on the high output side is selected.

Next, the operation of this embodiment configured as described above will be described in the flowchart of FIG. 7 and the flowchart of FIG. This will be explained with reference to the time chart of J. First, the user takes out the frozen food from the freezer compartment of the refrigerator and places it on the turntable 6 in the heating chamber 5. Then, after operating the defrosting key switch 14a, the star key switch 14b is operated. Then, the microcomputer 27 first sets a thawing cooking time Ht (time from the time when the start key switch 14a is operated) according to the weight W detected by the quantity sensor 31 (step i in FIG. 7).

Next, the microcomputer 27 determines whether the temperature T in the heating chamber 5 detected by the temperature sensor 7 exceeds a predetermined temperature t0, for example, 60°C (step j
). For example, if to<T, such as immediately after oven cooking is performed, the microcomputer 27 stores the temperature TO (initial temperature) in the heating chamber 5 at that time (step k);
The control circuit 26 is driven so as to energize the relay coil 29 (step fI). As a result, the fan motor 9a is energized even though the magnetron 8 is not energized, and the fan device 9 starts blowing air into the heating chamber 5 to forcibly cool the inside of the heating chamber 5. Due to forced cooling by this fan device 9,
When to≧T, the microcomputer 27 stores the operating time Ft of the fan device 9 up to that point (step m). Subsequently, the microcomputer 27
In step n), it is determined whether the initial temperature To is below 200°C. If T>200°C, output mode B in FIG. 10 is selected, and if it is 15200°C, output mode A is selected. Then, the control circuit 26 is driven to energize the relay coil 28 (relay switch 17 is turned on) with the on-duty ratio corresponding to each mode, and the magnetron 8 is caused to oscillate (steps p, q). Note that the fan device 9 continues to operate to cool the magnetron 8. The high frequency heating of frozen foods using this magnetron 8 is
The defrosting cooking is performed for the remaining time obtained by subtracting the forced cooling operation time Ft of the heating chamber 5 of the fan device 9 from the initially set defrosting cooking time Ht, and ends as the remaining time elapses. In this case, the output of the magnetron 8 is a value 1 corresponding to the remaining time of thawing cooking (Ht-Ft) at the time of transition from forced cooling of the heating chamber 5 by the fan device 9 to heating of the frozen food by the magnetron 8. For example, if the time is 7 minutes, in mode A the output will be approximately 320 watts, in mode B the output will be approximately 240 watts, and then as time passes, the output will change according to the remaining time of defrosting and cooking. Heat frozen food at level.

Then, the thawing cooking ends when the thawing cooking time reaches 0 (see FIG. 8 above).

On the other hand, in step j, if t0≧T, the process immediately moves to step q, where the magnetron 8 is driven in the output state of mode A, and the frozen food is thawed. and,
The defrosting cooking ends as the defrosting cooking time elapses.

As described above, according to this embodiment, if the temperature inside the heating chamber 5 is higher than a predetermined temperature at the start of thawing cooking, the inside of the heating chamber 5 is forcibly cooled by the fan device 9, and the inside of the heating chamber 5 is cooled by this forced cooling. When the temperature falls below the specified temperature, the magnetron 8
As the thawing cooking process automatically ends as the thawing cooking time elapses, the frozen food can be stored in the heating chamber 5 from the beginning. Since the heating chamber 5 is forcibly cooled, it is possible to prevent the frozen food from being exposed to a high-temperature atmosphere for a long time and causing the surface to become undercooked.

In this case, the fact exists that the frozen food is heated by high temperature air. Therefore, if the heating of the frozen food by the magnetron 8 is set only based on the ffi amount of the frozen food, if the temperature in the heating chamber 5 is high, there is a risk that the food will be overheated and end up being undercooked.

\ However, in this embodiment, the output time of the magnetron 8 is set to the remaining time after subtracting the forced cooling time in the heating chamber 5 by the fan device 9 from the thawing cooking time, so the problem of overheating is avoided. can be resolved. Moreover, the output level of the magnetron 8 is set to 5 in the heating chamber 5.
Since the temperature is changed depending on the initial temperature inside, overheating can be more reliably prevented. Furthermore, since the output level of the magnetron 8 is reduced over time, the frozen food can be thawed uniformly throughout.

In the above embodiment, the microcomputer 27 automatically sets the thawing cooking time based on the weight measured by the weight sensor 31, but this may be set manually. In addition, the present invention is not limited to the embodiments described above and shown in the drawings; for example, the fan device for forcedly cooling the inside of the heating chamber may be dedicated to cooling the magnetron. can be changed in various ways without departing from the gist.

[Effects of the Invention] As is clear from the above description, the present invention provides excellent effects as described below.

In the high-frequency heating device according to claim 1, when the temperature inside the heating chamber exceeds a predetermined temperature when defrosting and cooking, the fan device blows air into the heating chamber for forced cooling, and then at a predetermined time. Since the high frequency generator is enabled to be energized immediately, the waiting time until thawing and cooking starts is shortened.

Furthermore, in the high-frequency heating device according to the second aspect, when the high-frequency generator is enabled to be energized, the notification means notifies the user of this, so that the user can properly know when defrosting and cooking become possible.

In addition, in the high-frequency heating device according to claim 3, when thawing cooking is started, if the temperature inside the heating chamber exceeds a predetermined temperature, the fan device first blows air into the heating chamber for forced cooling. High-frequency heating by the high-frequency generator is performed at a predetermined time for a time corresponding to the set cooking time, so even if frozen food is stored in the heating chamber from the beginning, it can be thawed without overheating. can.

In the high-frequency heating device according to claim 4, heating of the frozen food by the high-frequency moderation device is performed only for the time remaining after subtracting the forced cooling time in the heating chamber by the fan device from the set thawing cooking time. Prevents frozen foods from being overheated.

Furthermore, in the high-frequency heating device according to the fifth aspect, since the output level of the high-frequency generator can be changed depending on the initial temperature of the heating chamber, overheating of the frozen food can be further prevented.

Furthermore, in the high-frequency heating device according to the sixth aspect, since the output level of the high-frequency generator changes over time, the frozen food can be thawed uniformly throughout.

[Brief explanation of the drawing]

Figures 1 to 6 show a first embodiment of the present invention. Figure 1 is a flowchart of defrosting cooking, and Figure 2 is a diagram showing the relationship between the temperature inside the heating chamber and the energization of the fan motor and magnetron during defrosting cooking. A time chart showing the relationship, Fig. 3 is an electric circuit configuration diagram, Fig. 4 is an external perspective view of the microwave oven, Fig. 5 is a partially cutaway plan view of the microwave oven, and Fig. 6 is a diagram of the microwave oven. It is a partially enlarged front view of a panel part. 7 to 10 show a second embodiment of the present invention. FIG. 7 is a diagram corresponding to FIG. 1, FIG. 8 is a diagram corresponding to FIG. 2, and FIG. 9 is a diagram corresponding to FIG.
This figure is a diagram corresponding to FIG. 3 showing only the control circuit, and FIG. 10 is a diagram showing the output level of the magnetron in relation to the remaining time of defrosting and cooking. In the figure, 1 is the main body, 5 is the heating chamber, 6 is the turntable, 7
is a temperature sensor, 8 is a magnetron (high frequency generator),
9 is a fan device, 10 is a duct, 14 is a key switch group, 26 is a control circuit, 27 is a microcomputer (control means, cooking time setting means), 30 is a buzzer (notification means)
, 31 is an ffi amount sensor. Applicant Toshiba Corporation #11 Figure Remaining time (minutes) Figure 10

Claims (1)

[Claims] 1. A device for heating an object by supplying high frequency waves emitted from a high frequency generator into a heating chamber, comprising: a temperature sensor for detecting the temperature inside the heating chamber; and a temperature sensor for blowing air into the heating chamber. a fan device for forcibly cooling the inside of the heating chamber; and a fan for forcibly cooling the inside of the heating chamber on the condition that the temperature detected by the temperature sensor exceeds a predetermined temperature when thawing and cooking of frozen food is selected. A high-frequency heating device comprising: a control means for operating the device and bringing the high-frequency generator into a cooking ready state in which electricity can be applied to the high-frequency generator at a predetermined time. 2. The high-frequency heating device according to claim 1, further comprising a notification device that performs a notification operation when the control device makes the cooking possible state. 3. A device that heats an object by supplying high frequency waves emitted from a high frequency generator into a heating chamber, which includes a temperature sensor that detects the temperature inside the heating chamber, and a forced cooling system that blows air into the heating chamber. a fan device for thawing the frozen food; a cooking time setting means for setting the thawing cooking time of the frozen food;
When thawing and cooking of frozen food is selected, on the condition that the temperature detected by the temperature sensor exceeds a predetermined temperature, a fan device is operated to forcibly cool the inside of the heating chamber, and the high-frequency generator starts freezing from a predetermined time. A high-frequency heating apparatus comprising: a control means for performing high-frequency heating of food for a time corresponding to a thawing cooking time set by the cooking time setting means. 4. Heating the frozen food by the high frequency generator takes a time corresponding to the difference between the thawing cooking time set by the cooking time setting means and the time required to cool the inside of the heating chamber to a predetermined temperature or less by operating the fan device. The high-frequency heating device according to claim 3, wherein the high-frequency heating device is implemented. 5. The high-frequency heating device according to claim 3 or 4, wherein the output level of the high-frequency generator is changed depending on the initial temperature within the heating chamber. 6. The high-frequency heating device according to claim 3, wherein the output level of the high-frequency generator changes over time.