JP3525254B2 - High frequency heating equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency heating device having an automatic thawing function for frozen foods.

[0002]

2. Description of the Related Art Heretofore, a high-frequency decompressing device of this type having a structure as shown in Japanese Patent Laid-Open No. 4-65095 has been known.

As shown in FIG. 8, this structure has the following structure.
A magnetron 3 that sends microwaves to the heating chamber 1 through the waveguide 2 and a magnetron 3 that is disposed outside the ceiling of the heating chamber 1 so as to face the holes 4 and detect the intensity of microwaves reflected from the food 5. Detection sensor 7 including antenna 6 and food 5 on mounting table 8
And a weight sensor 9 for measuring the weight of the food, and as shown in FIG. 9, the difference between the initial output voltage Va at the start of heating output by the detection sensor 7 and the output voltage Vb after 1 minute has passed Then, the weight Wf of the food is measured by the weight sensor 9, and the output of the magnetron 3 and the heating time are controlled by the microcomputer from the output voltage difference Va-Vb and the weight Wf.

In such a conventional high frequency heating apparatus, since the difference between the initial output voltage Va and the output voltage Vb after 1 minute is used, the absolute values of Va and Vb are required. However, the reliability of the absolute value at the time of mass production depends on the variation in the high-frequency detection sensitivity. Therefore, in the manufacturing process of the detection sensor 7, it is unavoidable to select the one whose sensor sensitivity falls within a predetermined range, which deteriorates the yield. In addition, there is a problem that the work of correcting the sensitivity of the detection sensor 7 and the sensitivity of the amplifier circuit is required, resulting in cost increase, and sensitivity deterioration due to long-term use is unavoidable, and lack of reliability. .

If only the food 5 placed on the table 8 is the food 5, the weight detected by the weight sensor 9 becomes the weight of the food 5 as it is, but the food 5 is placed together with the container. In this case, there was a problem that the net food weight could not be measured, resulting in overheating.

Further, since the antenna 6 is arranged outside the ceiling of the heating chamber 1, the steam generated from the food 5 may adhere to the antenna 6 to deteriorate the high frequency reception performance. Therefore, it is necessary to take measures such as covering the holes 4 with a resin plate.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-frequency heating device which does not cause overheating even when food is placed on a placing table together with a container.

Another object of the present invention is to provide a high-frequency heating apparatus which solves the above-mentioned problems, and which is further free from the vapor generated from foods adhering to the antenna and has higher reliability for thawing and heating.

[0009]

In order to solve the above-mentioned problems, the present invention provides a heating chamber, a mounting table for mounting an object to be heated provided in the heating chamber, and a high frequency wave in the heating chamber. , A weight sensor that detects the weight of the object to be heated placed on the mounting table, an antenna that detects the strength of the high frequency in the heating chamber, and a high frequency signal from the antenna is detected. A detection unit; and a control unit for controlling the output of the magnetron according to the output value of the weight sensor and the detection unit. The control unit detects the first weight value detected by the weight sensor and the output of the detection unit. The calculated smaller weight value of the second weight values is controlled as the weight value of the object to be heated.

According to the above-mentioned means of the present invention, the smaller weight value of the first weight value detected by the weight sensor and the second weight value detected by the detection means is defined as the weight value of the object to be heated. By doing so, the output of the magnetron and the heating time are controlled according to the weight of the object to be heated.

Further, in the above high-frequency heating apparatus, a waveguide for guiding the high frequency waves from the magnetron into the heating chamber and an exhaust port for discharging vapor generated from the object to be heated are provided on the wall surface of the heating chamber. By disposing the antenna on the wall surface of the waveguide, the vapor generated from the object to be heated does not adhere to the antenna, and the reliability of thawing and heating is further improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment) An embodiment of the present invention will be described below with reference to FIGS.

First, the structure of the high-frequency heating apparatus of the present invention will be described with reference to FIGS.

In the figure, reference numeral 11 is a heating chamber for accommodating a food product (hereinafter referred to as food) 12 which is an object to be heated. A mouth 14 is provided. Reference numeral 15 is a weight sensor disposed on the outer bottom of the heating chamber 11, which detects the weight of the object placed on the table 13 and outputs a signal to the control means 16 including a microcomputer. Reference numeral 17 is a waveguide disposed at the rear of the heating chamber 11, and a magnetron 18 is disposed at the end. Further, a square hole 19 is provided on the rear surface,
The rear part is covered with a metal cover 20. Inside the metal cover 20, an antenna 21 for detecting the strength of the high frequency in the heating chamber 11 and a detection means 22 for converting the detected strength of the high frequency into a voltage output and outputting the voltage output to the control means 16 are provided. . Reference numeral 23 is a door of the heating chamber 11.

Here, the control means 16 divides two output values of the initial output value Va at the initial stage of heating output from the detection means 22 and the minimum output value Vc within a predetermined time or the output value Vc after a predetermined time ( Va / Vc or Vc / Va) and the function of controlling the output and heating time of the magnetron 18 by this division value, and the mounting table 1 output from the weight sensor 15.
3 compares the first weight value Ww, which is the weight of the placed object (food 12 or the food 12 and the container), with the second weight value Wm, which is the weight of the food 12 calculated from the output value of the detection means 22. However, it has one or both of the function of controlling the output of the magnetron 18 and the heating time with the smaller weight value as the weight value of the food 12.

The general characteristic of the output of the detecting means 22 with respect to the state of the food 12 which is the object to be heated 12 is that the higher the weight of the food 12, the more the high frequency is absorbed by the food 12, and the high frequency that is not absorbed is received by the antenna 21. There is a characteristic that the high frequency becomes small and the output becomes small, and the dielectric loss of the food 12 below the freezing point has a temperature dependence.
There is a characteristic that the high frequency received by the antenna 21 increases and the output increases.

FIG. 3 shows the characteristics of the latter one, and shows a change with time of the detection output voltage by the detection means 22 when the minced 200 g having an initial temperature of −20 ° C. and −10 ° C. is thawed. Then, the detection means 22 uses the antenna 21.
The standard sensitivity (high sensitivity) and the dull sensitivity (low sensitivity) are used for comparison. As is clear from this figure, the low-sensitivity one has a smaller change in the detection output voltage in proportion to the insensitivity than the high-sensitivity one. Also, the change in the detection output voltage due to the heating time
The temperature at -20 ° C is higher than that at -10 ° C.

Under such a characteristic, as shown in the conventional example, the difference between the initial output value Va and the output value Vb after a predetermined time, for example, 1 minute, that is, Va-Vb is used to determine the food 12.
Although the output of the magnetron 18 and the heating time can be controlled by estimating the initial temperature of the detector, the value of Va-Vb of the detector having an initial temperature of -10 ° C and the detector 22 having a high sensitivity when the detector 22 has low sensitivity. Since it is close to the value of Va-Vb at the initial temperature of -10 ° C. in the case of sensitivity, it may be erroneously detected, and the precision control of the high frequency detection sensitivity of the detection means 22 including the antenna 21 must be strict. I didn't get it.

Further, the output curve delineating the detection output value is a high-order curve having an absolute value, that is, a minimum output value Vc. However, if the output value Vb after a predetermined time is a change value, the output value Vb is the minimum output value. It was on the output curve deviating from the value Vc and did not utilize the characteristics of the output curve having the minimum output value Vc.

Due to such a problem, in this embodiment, by utilizing the characteristic of the output curve having the minimum output value Vc, the initial output value Va output from the detecting means 22 and the minimum output value Vc within a predetermined time are obtained. Two output values are Va / Vc or V
The initial temperature of the food 12 is detected by division such as c / Va, and the control means 16 controls the high frequency output and heating time of the magnetron 18 based on this division value.

In FIG. 4, the initial output value Va is set to the minimum output value Vc within a predetermined time by using the detection means 22 having a variation of the detection sensitivity in the range obtained by the usual accuracy control from low sensitivity to high sensitivity. The correlation between the divided value and the initial temperature of the food 12 is shown. As apparent from the figure, the detection means 22
The sensitivity variation of 1 is offset by division, and the initial temperature of the food 12 can be detected by the correlation line. Then, even if the detection sensitivity deteriorates due to aging due to long-term use, the deterioration in sensitivity is offset by division, and the initial performance can be maintained.

When the initial temperature of the food 12 is estimated in this way, as shown in FIG. 5, the optimum heating time according to the weight of the food 12 and the initial temperature is known, so that the weight sensor 15 outputs the output. The control means 16 controls the output of the magnetron 18 and the heating time together with the weight value of the food 12 to be heated to optimally heat the food 12.

In this heating, generally, the control means 16
Is controlled so that it is heated with a strong high-frequency output in the initial stage of heating, and is then controlled to switch to a weak high-frequency output or an intermittent high-frequency output so that it is heated uniformly. A better thawing result can be obtained by adjusting the switching timing according to the above.

The high-frequency output of the high-frequency heating device is determined as a specification at the stage of planning the capability of the high-frequency heating device, and if the high-frequency output is determined, the minimum output value V
The approximate heating time required to output c can be determined by experiment. Then, this heating time is set as a predetermined time from the initial output value Va, and the output value after the predetermined time is divided as an apparent minimum output value Vc between the initial output value Va and the initial temperature of the food 12. Can be detected.

Further, as shown in FIG. 3, the detecting means 2
Since the output value from 2 shows a gentle change before and after the minimum output value Vc within a predetermined time, the change amount is also small with respect to the minimum output value Vc in a certain time range around the minimum output value Vc. Has become. Focusing on this, it is possible to set a predetermined allowable value around the minimum output value Vc, that is, an allowable value of the detection output voltage or the heating time within a range that does not affect the estimation of the initial temperature of the food 12.
Then, if the allowable value is set, it is possible to further cancel the variation in the detection sensitivity of the detection means 22.

As described above, according to the high frequency heating apparatus of the embodiment of the present invention, the initial output value Va and the minimum output value Vc within the predetermined time are divided by two output values, or the initial output value Va is obtained.
And dividing the two output values of the output value Vc after a predetermined time,
By controlling the high frequency output and the heating time of the magnetron 18 by this divided value, it is possible to cancel the variation of the detection means 22 and to reliably detect the initial temperature of the food 12, and to detect the detection including the antenna 21. There is an effect that the accuracy control of the means 22 becomes easy, and a high-frequency heating device excellent in reliability and productivity can be obtained.

Then, the food 1 placed on the placing table 13
2 is usually put in a container and its weight is measured together with the container by a weight sensor 15.

By the way, as described above, the weight of the food 12 is inversely proportional to the detection output. Based on this relationship, the means for detecting the weight of the food 12 from the detection output to control heating is For example, it is shown in Japanese Patent Application Laid-Open No. 2-306025 and Japanese Patent Application Laid-Open No. 4-65095.

However, with this means, even if the food 12 has the same weight, the detection output tends to be slightly different depending on the shape and the mounting position, and it is difficult to accurately convert the weight. Met.

For example, as shown in FIG.
By plotting the weights of g, 200 g, and 300 g of food 12 detected by the weight sensor 15 and the detection means 22, respectively, it can be understood that the weight detected by the detection means 22 has a larger variation.

100 g in a 200 g glass container,
Weight sensor 15 containing 200g and 300g of food 12
When the weights respectively detected by the detecting means 22 and the detecting means 22 are plotted, the weight value detected by the weight sensor 15 is the same as the value obtained by adding the weight of the container to the food 12, but the weight value detected by the detecting means 22 varies. , The food 12 mentioned above
It is within the range of the variation of the detected value when the weight of the chisel is detected.

When heating is performed under such a detected value,
When the food 12 contained in the container is heated by the weight value detected by the weight sensor 15, the food 12 is overheated, but when the food 12 is heated by the weight value detected by the detection sensor 22, the food 12 is heated within an allowable range.

Therefore, in this embodiment, the weight detected by the weight sensor 15 is set to the first weight value Ww, and the weight detected by the detection means 22 is set to the second weight so that the optimum heating result can be obtained. As the value Wm, the first weight value Ww and the second weight value Ww
Weight value Wm, whichever is smaller, that is, food 1
The heating time is set with the weight value of 2 as the weight of the food 12.

This execution process will be described with reference to FIG.

First, when automatic decompression is started, immediately after S
In 1 the control unit 12 detects the first weight value Ww, which is the physical weight, from the output value of the weight sensor 15, and in S2 operates the magnetron 18 to output a high frequency wave inside the heating chamber 11. In S3, the strength of the high frequency inside the heating chamber 11 is transmitted to the control unit 12 as the initial output value Va from the detection means 22. In S4, a second weight value Wm which is the detected weight is detected using the initial output value Va. Second weight value W in S5
If m is smaller than the first weight value Ww, it is determined that the container is placed together with the food 12, but in this example, considering the variation of the detection sensitivity, the second weight is more than 80% of the first weight value Ww. The case where the value Wm is small is used as the criterion. If the food weight W includes a container, the process proceeds to S6 and the second weight value Wm is adopted. However, normally, the process proceeds to S7 and the first weight value Ww is adopted.

Then, circulation is performed in S8 and S9. In S8, the detection output is continuously taken in for a predetermined time, for example, 40 seconds, and the minimum value during that period is set as the minimum output value Vc.
Reference numeral 9 is a conditional expression indicating whether 40 seconds have elapsed from the start of heating. After the lapse of 40 seconds, the process loops out from the circulation, and in S10, the food temperature Tp is estimated using the value obtained by dividing the initial output value Va by the minimum output value Vc. In S11, the optimum heating time Tm is calculated from the food temperature Tp and the food weight W substituted in S6 to S7. It circulates in S12 until 20% of the heating time Tm elapses, during which the magnetron 18 is continuously output. When time passes and the process proceeds to S13, the control unit 16 switches the magnetron 18 to intermittent output. S14 circulates until time reaches Tm time, and time T
When m ends, the flow shifts to S15, and the control means 16 stops the output of the magnetron 18 and ends the automatic defrosting.

As described above, according to the high frequency heating apparatus of the embodiment of the present invention, the first weight value Ww detected by the weight sensor 15 and the second weight value Wm calculated from the output value of the detection means 22 are obtained. By controlling the high frequency output of the magnetron 18 and the heating time with the smaller weight value of the food 12 as the weight value of the food 12, heating corresponding to the weight of the food 12 is performed. 1
2 will not overheat the food 12 even if placed,
There is an effect that it is possible to obtain a high-frequency heating device having high reliability for thawing and heating.

Further, in FIG. 1, the heated food 12
Water vapor generated from rises toward the upper surface of the heating chamber 11,
The gas is discharged to the outside of the high frequency cooking from the exhaust port 14 provided on the rear wall surface of the heating chamber 11 and the gap between the heating chamber 11 and the door 23. By the way, the antenna 21 is inside the metal cover 20 that covers the rear portion of the rectangular hole 19 on the rear surface of the waveguide 17, that is, the waveguide 1
Since it is arranged on the wall surface of 7, the water vapor does not flow into the waveguide 17 whose pressure loss is large due to the waveguide path,
Therefore, the vapor does not adhere to the antenna 21.

As described above, according to the high frequency heating apparatus of the embodiment of the present invention, since the antenna 21 is arranged on the wall surface of the waveguide 17, water vapor generated from the food 12 does not adhere to the antenna 21. The effect that the reception performance of the antenna 21 is not deteriorated is obtained.

[0040]

As is apparent from the above description, according to the present invention, either the first weight value detected by the weight sensor or the second weight value calculated from the output value of the detecting means is smaller. The weight value is the weight value of the food, and the control means controls the high frequency output of the magnetron and the heating time by this weight value, so that the heating corresponding to the weight of the food is performed, so that the container together with the container is placed on the mounting table. Even if the food is placed, the food is not overheated, and a high-frequency heating device having high reliability for thawing and heating can be obtained.

In the case where the antenna is arranged on the wall surface of the waveguide, water vapor generated from food does not adhere to the antenna, so that the reception performance of the antenna is prevented from being deteriorated and the reliability of thawing and heating is high. A high frequency heating device can be obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view of a high frequency heating apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of the same main part.

FIG. 3 is a characteristic diagram showing the relationship between the detection output voltage and heating time of the high-frequency heating device.

FIG. 4 is a characteristic diagram showing a relationship between a value obtained by processing the same detection output and an initial food temperature.

FIG. 5 is a characteristic diagram showing the relationship between the initial temperature of the food and the heating time.

FIG. 6 is a characteristic diagram showing the relationship between the detected weight and the physical weight of the high-frequency heating device.

FIG. 7 is a flowchart showing the same processing content.

FIG. 8 is a side sectional view of a conventional high-frequency heating device.

FIG. 9 is a characteristic diagram showing the relationship between the detection output voltage and heating time.

[Explanation of symbols] 11 heating chamber 12 Food (object to be heated) 13 table 15 Weight sensor 16 Control means 17 Waveguide 18 magnetron 21 antenna 22 Detection means Va initial output value Vc minimum output value Ww first weight value Wm second weight value

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI H05B 6/68 320 H05B 6/68 320N 320P 320V (58) Fields investigated (Int.Cl. ⁷ , DB name) F24C 7/02 H05B 6/68

Claims (2)

(57) [Claims] 1. A heating chamber, a mounting table for mounting an object to be heated provided in the heating chamber, a magnetron for supplying a high frequency to the heating chamber, and a heating object mounted on the mounting table. A weight sensor for detecting the weight of an object, an antenna for detecting the strength of a high frequency in the heating chamber, a detection means for detecting a high frequency signal from the antenna, and the magnetron according to the output values of the weight sensor and the detection means. And a control unit for controlling the output of the weight sensor, wherein the control unit determines the smaller one of the first weight value detected by the weight sensor and the second weight value calculated from the output of the detection means. A high-frequency heating device, which is controlled as a weight value of an object to be heated. 2. A wall surface of the heating chamber according to claim 1, wherein a waveguide for introducing a high frequency wave from the magnetron into the heating chamber and an exhaust port for discharging vapor generated from an object to be heated to the outside of the heating chamber are provided. The high frequency heating device according to claim 1, wherein the antenna is provided on a wall surface of the waveguide.