JP2010073467A - Microwave heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave heating apparatus in which frequency, with which a reflected wave becomes minimal according to a change while a foodstuff is being cooked, changes. <P>SOLUTION: The microwave heating apparatus includes microwave generating parts 3a-3d equipped with outputting parts 2a-2d connected with a plurality of semiconductor oscillating parts 1a-1d, reflection wave monitor parts 6a-6d for continuously monitoring a heating chamber 5 and a reflected wave level, a control part 4 to receive the signal and control output, and a threshold value 10 for not reaching breakage. When a total sum of signals of the reflected wave monitoring parts 6a-6d exceeds the threshold value 10, a negative feedback control is carried out so that the output of the semiconductor oscillating parts 1a-1d may become the threshold value 10 or less, and as a result, the semiconductors are prevented from being broken. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a microwave heating apparatus that heats an object to be heated by irradiating microwaves.

  A typical microwave heating apparatus that heats an object using a microwave is a microwave oven. In a microwave oven, microwaves are radiated from a microwave generator into a metallic heating chamber, and an object to be heated in the heating chamber is heated by the radiated microwaves.

Conventionally, as this microwave heating apparatus, a semiconductor oscillation unit, a division unit that divides the oscillation output of the semiconductor oscillation unit into a plurality, a divider that amplifies the divided oscillation output, and amplifies the divided oscillation output, respectively. And a detecting means for detecting a reflected wave between the combiner and the heating chamber, and changing the oscillation state of the oscillator according to the amount of the reflected wave detected by the detecting means. there were.
JP-A-56-134491

  However, in the conventional configuration, since the semiconductor oscillation units are synthesized by the synthesis unit, the reflected wave related to the oscillation output from one power supply port is constantly monitored, and the reflected wave becomes larger than a certain level. For example, by stopping the oscillation of the oscillator, changing or stopping the oscillation frequency, or changing and reducing the oscillation output, the semiconductor unit can be reduced without using a semiconductor oscillation unit protection means such as an isolator. It was something that could not be destroyed. However, even if the oscillation output is changed and reduced, it is unclear how much it is reduced. The control law is also very unclear. In addition, although it is said that the detection means for detecting the reflected wave between the heating chamber is detected, how much the reflected wave burden is added to each of the semiconductor oscillators when the reflected wave of the synthesis unit is detected. It is unclear whether the semiconductor oscillator is completely protected or not.

  In addition, there is no mention of the case where a plurality of semiconductor oscillating units and subsequent power supply ports are provided and space synthesis is performed in the heating chamber.

  The present invention solves the above-described problem, and even in a configuration in which a plurality of semiconductor oscillation units are provided, each reflected wave load is detected, and any one of the semiconductor oscillation units is not subjected to excessive reflected waves and is maximized. It aims at providing the microwave heating device which can irradiate a microwave.

In order to solve the above-described conventional problems, a microwave heating apparatus according to the present invention includes a microwave generation unit having an output unit connected to a plurality of semiconductor oscillation units, a heating chamber for storing an object to be heated, and a subsequent stage of the output unit. Is provided with a reflected wave monitor unit that constantly monitors the reflected wave level. A threshold value for determining a reflected wave level at which the semiconductor oscillating unit is not destroyed; and the control unit outputs an output of the semiconductor oscillating unit when a sum of signals of the reflected wave monitoring units exceeds the threshold value. By applying negative feedback control to the oscillation frequency so as to be less than the threshold value, the semiconductor oscillation unit is protected from excessive reflection wave energy, and the microwave is allowed up to the threshold value that allows the reflected wave. Since heating is performed, the continuity of heating can be maintained.

  Further, the microwave heating apparatus of the present invention includes a threshold corresponding to each output unit that determines a reflected wave level at which the semiconductor oscillation unit does not break down, and has a predetermined amount with a change amount that causes negative feedback with respect to the oscillation frequency. If exceeded, it is determined that the oscillation state has increased the amount of reflection from the heating chamber, and the operating frequency is changed by searching for the frequency at which the reflection level detected from the signal of the reflected wave monitor is minimized. Therefore, it is possible to reset to the frequency that minimizes reflection again, apply negative feedback control to the microwave oscillation frequency, and maximize the output that changes the oscillation frequency of the microwave generator. The heating at can be reproduced.

  The microwave heating device of the present invention is located at the rear stage of the output unit, the microwave generation unit having the output unit connected to the plurality of semiconductor oscillation units, the heating chamber for storing the object to be heated, and constantly monitors the reflected wave level. A reflected wave monitor unit; a control unit that receives a signal from the reflected wave monitor unit and controls the output of the output unit; and a threshold value that determines a reflected wave level that is not destroyed by the semiconductor oscillation unit. When the sum of the signals of the reflected wave monitoring unit exceeds a threshold value, negative feedback control is performed so that the output of the semiconductor oscillation unit becomes equal to or less than the threshold value. Even if the food is overheated or the food wrap swells and the volume of the object to be heated increases, causing the impedance of the heating chamber to change, the dielectric constant of the object to be heated changes during heating. However, negative feedback control is applied to the change, so that the oscillation frequency of the semiconductor oscillation part becomes an appropriate frequency so that the threshold value is not exceeded, and the reflected wave is suppressed and an excessive reflected wave is generated in the semiconductor. Returning to the oscillating portion, the semiconductor element is prevented from being destroyed. As a result, the reflected wave level can always be kept low and the heating concentration on the food can be maximized.

  According to a first aspect of the present invention, there is provided a microwave generation unit having a plurality of semiconductor oscillation units connected to an output unit, a heating chamber that houses an object to be heated, and a reflected wave that is positioned downstream of the output unit and constantly monitors the level of the reflected wave A monitor unit; a control unit that receives a signal from the reflected wave monitor unit and controls the output of the output unit; and a threshold value that determines a reflected wave level at which the semiconductor oscillation unit is not destroyed. When the sum of the signals of the part exceeds the threshold value, negative feedback control is performed so that the output of the semiconductor oscillation part becomes less than the threshold value, and the oscillation frequency of the microwave generation part is changed, so that the food being heated Even if a phenomenon occurs in which the impedance of the heating chamber changes due to the fall of the food or the wrapping of the food wrap and the bulk of the object to be heated, the negative feedback control is applied to the change so that the threshold value is not exceeded. From semiconductor The oscillation frequency of section acts so that the appropriate frequency, the semiconductor device excessive reflected wave by suppressing the reflected wave returns to the semiconductor oscillation unit is intended to prevent the destruction. As a result, the reflected wave level can always be kept low and the heating concentration on the food can be maximized.

  The second invention uses a microcomputer as the control unit. In this application, where digital processing such as various types of processing and storage functions are required for process processing, many microcomputers used in many other home appliances handle a large quantity and refine process rules. Along with the increase in diameter of wafers, the trend is a sharp reduction in price, which is excellent in terms of economy and performance. From this point of view, adopting a microcomputer whose cost performance is expected to evolve in the future can be very economical and performance advantageous for this equipment.

  The third invention transplants the microcomputer function of the device of the present invention on the microcomputer that controls the entire device, greatly reduces the redundancy and exhibits the economic effect, and two parts are one part From the viewpoint of making it easier, the number of parts can be reduced and the entire system can be simplified.

  According to a fourth aspect of the present invention, there is provided a microwave generation unit having an output unit connected to the semiconductor oscillation unit, a heating chamber that houses an object to be heated, a reflected wave monitor unit that is positioned downstream of the output unit and constantly monitors a reflected wave level. A control unit that receives the signal of the reflected wave monitor unit and controls the output of the output unit, and a limit threshold value corresponding to each output unit that determines a reflected wave level at which the semiconductor oscillation unit does not break, When the amount of change exceeds the limit threshold value, it is determined that the oscillation state is such that the amount of reflection from the heating chamber is increased, and the control unit quickly reduces the output of the reflected wave monitoring unit. As a result, it is possible to realize a highly reliable system in which the semiconductor is not destroyed even by transient excessive reflected waves. After that, the frequency at which the reflection level detected from the signal of the reflected wave monitor is minimized, the oscillation frequency of the microwave generator is changed, the output is returned to the original high level, and then negative feedback control is applied to generate microwaves. The output frequency is temporarily reduced, but after determining a frequency with less reflected waves, the same high output is obtained as before, so the impedance in the heating chamber changes. However, it is possible to provide a device with excellent usability without promptly recovering the original output and without extremely increasing the heating time.

  The fifth aspect of the invention integrates the frequency of negative feedback, and if it exceeds a certain predetermined amount, it is determined that the oscillation state is increased in the amount of reflection from the heating chamber, and from the signal of the reflected wave monitor unit The frequency at which the detected reflection level is minimized is searched and the oscillation frequency of the microwave generator is changed. The frequency of negative feedback is increased and the deviation of the reflected wave from the minimum frequency is detected. The frequency is reset, the feedback of the reflected wave to the semiconductor is detected, and before the semiconductor breaks down, the oscillation frequency of the microwave generator is changed to the optimum frequency with less reflected wave, and the resistance to the reflected wave is remarkably increased. It is to improve.

  In the sixth aspect of the present invention, the frequency at which negative feedback is applied is integrated, and when the amount is less than a predetermined amount, the control unit thins out the monitoring opportunity of the reflected wave monitor unit, and heats stably and the reflected wave greatly fluctuates. When there is not, the negative feedback control is configured to extend the monitoring interval, and the job is time-shared with other controls, thereby reducing the overall control unit balance and contributing to the control unit cost reduction. Is.

  The seventh invention provides a first threshold value and a second threshold value, the second threshold value is a threshold value larger than the first threshold value, and the control unit is a reflected wave monitor unit Negative feedback control is performed when the output from the generator exceeds the first threshold value and less than the second threshold value. When the output exceeds the second threshold value, the oscillation state is increased in the amount of reflection from the heating chamber. The oscillation frequency of the microwave generator is changed by searching for the frequency at which the reflection level detected from the signal of the reflected wave monitor is minimized.

  In this way, for excessive reflected waves exceeding the second threshold, the frequency at which the reflection level is minimized is quickly searched and reset, so that the resistance to the reflected waves is significantly improved, and at normal times. Since the regular negative feedback control is performed, the constant control (stable control) of the reflected wave can be maintained, so that a highly reliable reflected wave protection system can be provided.

  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)
FIG. 1 is a configuration diagram of a microwave heating apparatus according to the first embodiment of the present invention.

In FIG. 1, the microwave generation units 3 a to 3 d are configured from output units 2 a to 2 d configured using semiconductor elements, and reflected wave monitoring units 6 a to 6 d that detect reflected power reflected from the inside of the heating chamber 5. Has been. Basic weak signals for generating microwaves are generated by the semiconductor oscillation units 1a and 1b. To realize the semiconductor oscillation units 1a and 1b with as few configurations as possible, the semiconductor oscillation units 1a and 1b are formed by the power distribution units 8a and 8d. Each of them is divided into two, four in total, and input to the microwave generators 3a to 3d.

  Further, the microwave processing apparatus of the present invention has a heating chamber 5 having a substantially rectangular parallelepiped structure that accommodates an object 9 to be heated, and the heating chamber 5 has a left wall surface, a right wall surface, a bottom wall surface, an upper wall surface made of a metal material, An open / close door (not shown) that opens and closes to store the inner wall and the object 9 to be heated, and a mounting table on which the object 9 is mounted, and is configured to confine the supplied microwave inside. is doing. And the output of the microwave generation parts 3a-3d is transmitted, and the electric power feeding parts 7a-7d which radiate | emit the microwave into the heating chamber 5 are arrange | positioned at the wall surface which comprises the heating chamber 5. FIG.

  In the present embodiment, the power feeding portions are arranged at the approximate center of the left wall surface and the right wall surface of the opposing configuration, respectively, and the power feeding portions 7c and 7d are respectively provided at the approximate center of the upper wall surface and the bottom surface of the heating chamber 5. The structure which has arranged is shown. The arrangement of the power feeding unit is not limited to the present embodiment, and a plurality of power feeding units may be provided on any wall surface, and adjacent to each other such as the right wall surface and the bottom wall surface that are not opposed surfaces. You may comprise the electric power feeding part which becomes a pair by a combination.

  The power amplifiers in the output units 2a to 2d are amplified by several tens of dB or more by a cascade amplifier on the printed circuit board. The circuit is formed by a conductor pattern formed on one side of a dielectric substrate made of a low dielectric loss material. The matching circuit is arranged on the input side and the output side of each semiconductor element so that the semiconductor element which is an amplifying element of each amplifying section is operated satisfactorily.

  The microwave transmission path connecting each functional block forms a transmission circuit having a characteristic impedance of about 50Ω by a conductor pattern provided on one surface of the dielectric substrate.

  The power distribution units 8a and 8b may be in-phase distributors that do not generate a phase difference between outputs such as Wilkinson type distributors, or may have a phase difference between outputs such as branch line type or rat race type. It may be the resulting distributor. The power distribution units 8a and 8b transmit substantially half of the microwave power input from the oscillation units 1a and 1b to the respective outputs.

  If the control unit 4 selects a frequency with as few reflected waves as possible, it can maximize the heat transfer power received by the article 9 to be heated, contribute to speed cooking, and reduce the heat loss of the semiconductor element due to the reflected wave power. Also, the heat resistance reliability of the semiconductor is improved.

  However, it is inevitable that the object to be heated 9 is affected by the temperature of microwave heating during cooking. For example, it rarely occurs that the article 9 to be heated falls due to thermal expansion during heating or falls. It is also possible that the dielectric constant gradually changes as the food temperature rises. Moreover, although the habit of lapping is often seen in the microwave heating apparatus, it can be seen that this also swells during heating and the volume of the object to be heated increases. At times like this. The impedance inside the heating chamber as viewed from the heating chamber 5 changes, and it is predicted that the minimum reflection frequency changes every moment as shown in FIG. Point a in FIG. 2 is an initial frequency characteristic. When a change in physical properties of the article 9 to be heated appears, a transition is made to a curve of point b in FIG. And, when the heated object 9 falls or rolls during heating, the dielectric constant changes as the temperature of the food rises, or the heated heated object 9 wrapped increases, It is predicted that the frequency characteristics will change up to a point c of the alternate long and short dash line. At that time, the reflectance increases by d. That is, it is used in a state where there are many reflections. This increases the reflection duty of the semiconductor. For example, if the change is larger, it is assumed that the reflection increases and breaks down.

  Therefore, as a means for avoiding this, it is necessary to always perform negative feedback control so that the frequency becomes a minimum frequency so as not to change the frequency.

  This will be described with reference to FIG. First, the routine starts from the beginning, and in step 1, the reflections from the reflected wave monitoring units 6a to 6d are monitored. Next, in step 2, the total reflection of the reflection monitor units 6a to 6d is calculated. Next, in step 3, it is lowered by a predetermined minute frequency fluctuation amount Δf. In the lowered state, the total reflection of the reflection monitor units 6a to 6d is calculated. Next, in step 5, it is determined by monitoring the reflected wave monitor unit whether the reflection has increased. If yes, the Δf frequency is increased in step 6. Next, in step 7, the total reflection of each of the reflection monitor units 6a to 6d is calculated. Next, in Step 8, it is determined whether or not the reflection has increased. If No, the negative feedback control is completed and the frequency is determined. If yes, go back to step 2. If it repeats in the loop of step 2 to step 8, it counts a predetermined number of times, and if it is satisfied, the frequency is determined.

  On the other hand, if “No” in step 5, the Δf frequency is lowered in step 10. Next, in step 11, the total reflection of each of the reflection monitor units 6a to 6d is calculated. In step 12, it is determined whether the reflection has increased, and if Yes, the frequency is determined. If No, the process jumps to Step 6 and branches to a routine for increasing the Δf frequency. Thereafter, the frequency is determined as described above. The frequency variable range is the ISM band (2.45 G ± 0.05 G), and the frequency can be varied for negative feedback in this sequence freely according to this sequence. Because of such a complicated sequence, it seems that it is appropriate to use a microcomputer for the control unit.

  In order to simplify the system, there is a microcomputer that controls the entire existing equipment, but by inserting this task into it, the task can be performed in parallel by one microcomputer, and the system is greatly improved. It is also possible to reduce the number of parts and achieve an economic effect.

  Further, when the frequency of the negative feedback is integrated and exceeds a predetermined amount, it is determined that the oscillation state in which the amount of reflection from the heating chamber 5 is increased and the signals of the reflected wave monitoring units 6a to 6d are determined. If the frequency at which the reflection level detected from the signal is minimized and the oscillation frequency of the microwave generation unit 3 is changed, a more reliable system can be constructed.

  On the other hand, if a stable state with a low frequency of negative feedback continues, the monitoring unit 4 thins out the monitoring opportunity, and the control unit 4 can concentrate on processing another task and effectively use the task. The total performance of the control unit 4 can be improved.

  In addition, a first threshold value and a second threshold value are provided, the second threshold value is set to a threshold value larger than the first threshold value, and the control unit 4 includes the reflected wave monitoring units 6a to 6a. When the output from 6d exceeds the first threshold value and is less than the second threshold value, the negative feedback control described above is performed. When the output exceeds the second threshold value, the amount of reflection from the heating chamber increases. By determining that the oscillation state has been achieved, the frequency at which the reflection level detected from the signals of the reflected wave monitoring units 6a to 6d is minimized is obtained, and the oscillation frequency of the microwave generating unit 3 is changed. It is also possible to build a more reliable system.

In the present embodiment, the frequency at which negative feedback is applied is integrated, and when a certain predetermined amount is exceeded, it is determined that the amount of reflection from the heating chamber 5 is in an oscillating state, and the reflected wave monitor The frequency at which the reflection level detected from the signals of the parts 6a to 6d is minimized is calculated. The frequency at which negative feedback is applied within a predetermined time, that is, the frequency is calculated, and when this frequency exceeds a predetermined amount, heating is performed. It is determined that the oscillation state is such that the amount of reflection from the chamber 5 has increased, and the reflected wave monitoring units 6a to 6d.
The frequency at which the reflection level detected from the above signal is minimized may be obtained, and this also makes it possible to construct a highly reliable system.

  As described above, the microwave heating apparatus according to the present invention can provide a device that has a plurality of power supply units and prevents destruction of a semiconductor from reflected waves from a power supply unit that radiates microwaves. It can also be applied to uses such as a heating device using dielectric heating, a garbage disposal machine, or a microwave power source of a plasma power source which is a semiconductor manufacturing device.

The system block diagram of the microwave heating apparatus in embodiment of this invention The characteristic view which shows the change of the frequency spectrum accompanying the change of the to-be-heated material of this invention The flowchart which shows the flow of the negative feedback control in embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor oscillation part 2 Output part 3 Microwave generation part 4 Control part 5 Heating chamber 6 Reflection monitor part 10 Threshold value

Claims (7)

A microwave generation unit having a plurality of semiconductor oscillation units connected to the output unit, a heating chamber that houses an object to be heated, a reflected wave monitor unit that is positioned downstream of the output unit and constantly monitors the reflected wave level, and the reflection A control unit that receives a signal from the wave monitor unit and controls the output of the output unit; and a threshold value that determines a reflected wave level that is not destroyed by the semiconductor oscillation unit, and the control unit includes each of the reflected wave monitor units A microwave heating device configured to change the oscillation frequency of the microwave generation unit by performing negative feedback control so that the output of the semiconductor oscillation unit becomes equal to or less than the threshold when the sum of the signals of the above exceeds the threshold value . The microwave heating apparatus according to claim 1, wherein the control unit is configured to always perform negative feedback control using a microcomputer. The microwave heating apparatus according to claim 1 or 2, wherein the microcomputer is configured so as to be used in combination with a microcomputer that controls the microwave heating apparatus. A microwave generation unit having a semiconductor oscillation unit connected to a plurality of output units; a heating chamber that houses an object to be heated; a reflected wave monitor unit that is positioned downstream of the output unit and constantly monitors a reflected wave level; and the reflection A control unit that receives a signal from the wave monitor unit and controls the output of the output unit, and a threshold threshold value corresponding to each output unit that determines a reflected wave level at which the semiconductor oscillation unit does not break down. When the amount of change exceeds the limit threshold, the control unit quickly reduces the output of the reflected wave monitor unit, and then the reflection level detected from the signal of the reflected wave monitor unit is minimized. 4. The structure according to claim 1, wherein the frequency is calculated and the oscillation frequency of the microwave generation unit is changed, and then the output is restored to perform negative feedback control to change the oscillation frequency of the microwave generation unit. Microwave heating apparatus according to item 1. The frequency of negative feedback is integrated, and when a certain predetermined amount is exceeded, the frequency at which the reflection level detected from the signal of the reflected wave monitor unit is minimized is obtained and the oscillation frequency of the microwave generating unit is changed. The microwave heating device according to any one of claims 1 to 4. The microwave heating apparatus according to any one of claims 1 to 5, wherein the frequency at which negative feedback is applied is integrated and the control unit is configured to thin out the monitoring timing of the reflected wave monitoring unit when the frequency is less than a predetermined amount. A first threshold value and a second threshold value greater than the first threshold value are provided, and the control unit outputs the second threshold value when the output from the reflected wave monitoring unit exceeds the first threshold value. When it is less than the threshold value, negative feedback control is performed, and when the second threshold value is exceeded, it is determined that the amount of reflection from the heating chamber is in an oscillating state, and the signal of the reflected wave monitoring unit The microwave heating device according to any one of claims 1 to 6, wherein a frequency at which a reflection level detected from the wave is detected is changed to change an oscillation frequency of the microwave generation unit.

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