JPH0755152A - Apparatus and method for high-frequency heating - Google Patents

Abstract

PURPOSE:To suppress a temperature difference of food due to a position to about 1 deg.C by emitting a high-frequency wave for a predetermined time at the time of a specific surface temperature of food, and then alternately repeating an operation for continuing a state that the wave is not emitted for a predetermined time. CONSTITUTION:Triacs 22, 23 as means for turning ON and OFF a high-frequency wave emitting source (rotary antenna) are provided. When a surface temperature of food 3 is a TEMP2 or higher of a low temperature and a TEMP1 or lower of a high temperature, a heating operation with power of predetermined high-frequency power POWER1 for an emission continuing time PTIME1 hour and a heating operation for continuing a state that a high-frequency wave is not emitted for an emitting stopping time STIME1 hour are alternately repeated. Thus, uniform heating in which a temperature difference of the food 3 at a position is suppressed to about 1 deg.C can be conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heating a vacuum cooking method, which has become widespread in recent years, by using a high frequency heating device.

[0002]

2. Description of the Related Art Vacuum cooking is a process in which vacuum-packed food is roasted in a hot water bath or a steam oven at a temperature of 55 ° C. to 95 ° C.
It is cooked at a low temperature up to about ℃, and it is vacuum packed so that the flavor is not impaired.Because the temperature is low, the muscles and fibers are not hard and soft, and at a temperature where protein division does not occur. Since it is cooked, the yield is very high, it can be stored for about a week, and it has the advantage of being convenient for large-scale supply at hotel banquets, etc., and it has spread rapidly.

[0003]

However, the bath temperature 42 to 4
As is easily inferred from the humidity environment in the bathroom of about 3 ° C, the humidity environment of the kitchen where hot water of about 60 ° C or higher is placed is not preferable and improvement is strongly desired. It was In addition, the fuel efficiency for maintaining the hot water temperature is not ridiculous and is expected to be improved. Even in the steam oven, it is almost the same.

As a solution to this problem, it has been considered to use a high-frequency heating device such as a microwave oven, but the finishing temperature range required for vacuum cooking is about 1 ° C., which is not a level that can be realized and the conventional technique of the microwave oven. The upper limit of the finishing temperature range was about 20 ° C.

The present invention is intended to realize a finishing temperature range of 1 ° C. by a high-frequency heating device which has been impossible in the past.

[0006]

In order to solve the above problems, the present invention has the following constitution.

It has a heating chamber, a door, a high frequency irradiation source, a food placing table, a food surface temperature detecting means, and a control means.
The control means (1) keeps the highest temperature portion of the food from exceeding the finishing temperature T1 as a function of the type, weight, shape, and finishing temperature of the food to be heated, and raises the temperature of the lowest temperature portion by heat conduction from the surroundings. Five numerical values determined to do, namely, high temperature TEMP1 and low temperature TEM
P2, a constant high frequency power POWER1, an irradiation duration PTIME1 of the high frequency power, a means for storing respective values of STIME1 which is a time for stopping the high frequency irradiation, (2) a time measuring means, and (3) It has means for connecting and disconnecting the high-frequency irradiation source, and (4) means for taking in the output of the food surface temperature detecting means. When the food surface temperature is TEMP2 or more and TEMP1 or less, POWER1 electric power causes PTIME1
STI for high frequency irradiation for a long time, and then not high frequency irradiation
An operation in which the ME lasts for 1 hour is alternately repeated.

Further, in this structure, TEMP1, TEM
The determination of P2, STIME1, and PTIME1 is performed as follows. Using an optical fiber thermometer with at least two temperature sensitive elements, one temperature sensitive element is inserted in the highest temperature part of the food, the other is inserted in the lowest part, and the food is irradiated with high frequency by constant power by manual operation, After determining the output of the food surface temperature detection means at the time when the highest temperature part of the food reaches the finishing temperature T1 as TEMP2, until the maximum temperature of the food decreases to a set temperature T2 which is about 1 ° C lower than the finishing temperature. High frequency irradiation is stopped, and high frequency irradiation is performed with POWER1 power until T1 is reached again. This high frequency irradiation and stop are repeated until the maximum temperature of the food rises and falls between T1 and T2, and the minimum temperature portion is T2. The output of the food surface temperature detecting means at the time when the temperature reaches T is determined to be TEMP1, and T1 and T2
Substantially average time values during a plurality of heatings during the interval and substantial average time values during a temperature decrease are defined as PTIME1 and STIME1, respectively.

[0009]

According to the present invention, with the above-described structure, the output of the food surface temperature detecting means and the temperatures of the maximum temperature portion and the minimum temperature portion of the food can be corresponded, and at the same time, the thermal properties of the food heating and heat diffusion can be determined. By introducing PTIME1 and STIME1 that have been replaced with the irradiation time and stop time taken into consideration, from the time when the food surface temperature TEMP2 is exceeded, POWER1
With high power PTIME for 1 hour High frequency irradiation stop STIME1
By repeating the operation of stopping the irradiation for the same time, the food is heated even at the temperature of the highest temperature part without exceeding the finishing temperature T1 and the heat is diffused from the high temperature part to the low temperature part, and the temperature of the lowest temperature part of the food is gradually increased. And finally reaches T2 [= finishing temperature−approximately 1 ° C.]. At that time, the food surface temperature should be TEMP1 (because TEMP1 is previously determined as a food surface temperature set value when the temperature of the lowest temperature portion becomes T2 in the constant setting experiment. ) Repeating the irradiation and stopping as the food surface temperature changes from TEMP2 to TEMP1.
By performing the heating between them, it is possible to realize uniform heating while suppressing the temperature difference of the food product by about 1 ° C.

In determining these constants, the maximum and minimum temperatures of the food due to heating are monitored by using an optical fiber thermometer, and the correlation with the output of the food surface temperature detecting means is obtained to obtain an accurate temperature easily. To be

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a combination of a perspective view and an electric circuit diagram of the inside of the heating chamber of the high-frequency heating device of the present invention. A food placing table 2 is provided inside the heating chamber 1 indicated by a chain double-dashed line, and a food item 3 (vacuum-packed pork in FIG. 1) is placed thereon. As will be described later, the thermistors 4, 5 and 6 are incorporated in the food placing table 2 (shown in FIGS. 3 and 4. Therefore, only the lead wire is drawn in FIG. 1), and the three thermistors are connected to the control circuit 7. It The electric circuit includes a power outlet 8, a fuse 9 inserted in both poles, a noise filter coil 10, a heating chamber lighting lamp 11, a lamp relay 12, a magnetron heater transformer 13, a relay 14, and three door-linked relays. Latch switches 15, 16 and 17, main relays 18 and 19, short switch 2 linked to the door
0 and 21, triacs 22 and 23, triac control circuits 24 and 25, high voltage transformers 26 and 27, and magnetrons 28 and 29. A power supply line is connected to the control circuit 7 from the back of the coil 10.

FIG. 2 is a sectional view of the main part of the heating device according to the present invention as viewed from the right side. The heating chamber 1 is made of a stainless thin plate and has a substantially rectangular parallelepiped shape. On the side surface, one fixture 30 made of heat-resistant resin is provided at the front and the rear. The food placing table 2 is placed on this. A choke (radio wave maze) 31 is provided on the rear wall of the heating chamber to penetrate a part of the food placing table 2. Rotating antennas 32 and 33 and rotating stirrer motors 34 and 35 are provided at the centers of the top and bottom of the heating chamber, and waveguides 36 and 37 connecting these to the magnetrons 28 and 29.
To provide. To protect the rotating antenna, polypropylene resin protective plates 38 and 39 are provided on the top surface and crystallized glass on the bottom surface, and a door 40 is rotatably provided at the opening of the heating chamber for magnetron cooling. Fan motor 4
1, an exhaust air passage 42, and an operation portion 43 above the door.

FIG. 3 is a plan view, a side view, and a front view of the food placing table 2. A rod-shaped body 44, which is made of a stainless steel plate having a thickness of 0.3 mm and whose cross section is a circle having an inner diameter of 1.5 mm in the upper part and a straight line of about 10 mm following the lower part, is formed.
Books (however, in FIG. 3, only nine are drawn to avoid complication) are arranged at equal intervals through a spacer 45 having a length of 15 mm, and the upper end and the lower end are fixed by long screws 46 and nuts 47. At the central portion of the lower end, a stainless steel lead metal fitting 48 having a substantially U-shaped cross section and a tube 49 fixed to the metal fitting 48 are fixed with screws 50. The three crosses drawn in the center of the plan view mean that the thermistors 4, 5 and 6 are at that position.

FIG. 4 is a perspective view of each portion of the food placing table 2, and FIG. 4A is a partially cutaway perspective view of the rod-shaped body 44. Holes 51 are formed at both front and rear ends, and the thermistor 4 is inserted in the central portion. (B) is a perspective view of the spacer 45. A hole 52 having the same diameter as the hole 51 is provided. (C)
[Fig. 6] is a partial perspective view showing a state in which a drawer fitting 48 is removed. Instead of the spacer 45, taps 53 are cut on the front and rear and upper and lower surfaces between the rod-like bodies 44, and mounting fittings 55 having through holes 54 on the left and right are provided. The tube 49 is fixed to the portion. Holes 57 are formed in the top and bottom and the rear surface of the drawer metal 48 at positions corresponding to the taps 53. The lead wire of the thermistor shown in (a) passes through the gap between the central portion 56 and the mounting bracket 55, passes through the inside of the tube 49, and is drawn out to the outside.

FIG. 5 is a partial circuit diagram of the inside of the control circuit 7. The primary side of the power transformer 58 is connected behind the coil 10 as shown in FIG. The secondary side is connected to the VCC terminal of the microprocessor 60 via the DC circuit 59.
It branches from the front of the DC circuit 59 and is connected to the P4 terminal of the microprocessor 60 via a waveform shaping circuit 61 composed of one transistor. One side of each of the thermistors 4, 5 and 6 is connected to a + 5V power source, and the other side is grounded via a resistor and is also connected to the terminals IN 1, 2 and 3 with AD conversion function of the microprocessor 60. Microprocessor 60 P20 to P2
The five terminals are connected to the triac control circuits 24 and 25 and the relays 12, 14, 18 and 19 via drive circuits 62, 63, 64, 65, 66 and 67, respectively. Keyboard 68 is R of microprocessor 60
0, R1, R2, R3, P0, P1, P2 and P3 terminals are connected. Various circuits are included in the control circuit 7 in addition to these, and various circuits are connected to the microprocessor 60, but it is complicated and is not an essential part of the present invention, and therefore the description thereof is omitted. Further, a central processing unit, a register, a RAM, a ROM, various input / output terminals, an interrupt terminal and the like are provided inside the microprocessor 60, but description thereof will be omitted because they are becoming common sense.

Next, a part of the outline of the program written in the ROM of the microprocessor 60 will be described. Figure 6
Is the first half of the program flow chart. When the control circuit of FIG. 5 is activated, first, the input of TEMP1 is requested. Although the display section is omitted and not shown in FIGS. 6 and 1, TEMP1? Is displayed. The operator taps the keyboard 68 to input a temperature, for example, 59 ° C. When the input is completed, the input of ON1 is requested next, and similarly OFF1, PTIME1, STIME1, TE
MP2, ON2, OFF2, PTIME2, STIME
Enter 2. Each of these constants is stored in an arbitrary fixed RAM area. When all the constants have been entered, the start button wait state is entered. When the start is pressed, RA first
The value of PTIME2 is substituted into an arbitrary fixed RAM area named as. RA, which is called a flag area, which is then arbitrarily determined
1 in a specific bit named CYCLE in part of M
To Similarly, assign the value of ON2 to RB, and DUT
Set the Y flag bit to 1.

Next, it is checked whether or not the unit time has elapsed. As shown in FIG. 5, since the AC power supply waveform is connected to the P4 terminal of the microprocessor 60 via the waveform shaping circuit 61, the square wave corresponding to only the positive side of the AC is input to the P4 terminal. It Time can be measured by counting this square wave. The unit time is usually one square wave or one second counted from 50 to 60 square waves. In the present invention, the time is one square wave. Therefore, if you input the above ON1, OFF1 etc. in seconds, it will be multiplied by 50 or 60 in the following calculations,
It goes without saying that it is necessary to convert the time into one square wave. When a unit time has elapsed, the process proceeds to the T side, the operation of subtracting 1 from the numerical value stored in the RA is executed, and the result is stored in the RA. Similarly, RB also subtracts 1 from the numerical value. Then proceed to the temperature check. If the unit time has not elapsed, the process proceeds to the F side, skips RA and RB, and proceeds to the temperature check.

As shown in FIG. 5, the thermistors 4, 5 and 6 are respectively connected in series with a resistor and connected to a constant DC value of +5 V. When the temperature rises, the resistance value of the thermistor decreases, so IN1, Voltages corresponding to the temperatures of the thermistors 4, 5 and 6 are input to the IN2 and IN3 terminals, respectively. These three input voltages are AD converted and handled as digital values. Now, these three temperatures are compared with TEMP2. If any one of the three temperatures is equal to or larger than TEMP2, the process proceeds to the T side, and the process proceeds to B, that is, the program of FIG. This will be described later. All three temperatures are TEM
If it is lower than P2, proceed to F side and then check the CYCLE flag. If this bit is 1, proceed to the T side, then proceed to check the DUTY flag, and if 1 then T
Side, proceed to the numerical check of RB. If RB is not 0, proceed to the F side and RA numerical value check. If this is also not 0, proceed to F side and turn on the radio wave, that is, output all 1s from terminals P20 to P25 of the microprocessor 60.
After that, the process returns to the above unit time elapsed check. Thereafter, this loop is repeated many times, and the numerical values of RA and RB are decremented by 1 each time a unit time elapses. RB becomes 0 in that. Then, proceed to the T side of the RB check, substitute the numerical value of OFF2 into RB this time, then change the DUTY flag to 0, RA
Proceed to check. If not 0, the process proceeds to the F side and returns to the unit time elapsed check again. Follow the same route again, but this time D
Since the UTY flag is 0, the flag check advances to the F side, the RB check advances to the F side, and the RA check advances to the F side.
Go to the side and execute the radio wave OFF. This is to set the outputs of the P20 and P21 terminals in FIG. 5 to zero. Return to the unit time elapsed check again and go around this new route. Among them, RB becomes 0, proceed to RA check on the T side, and RA
Since it has not become 0 yet, the process proceeds to the F side, and the process returns to the process of substituting ON2 into RB two higher than the unit time elapsed check. In this way, RA becomes 0 while repeating ON2 and OFF2. Then, the radio wave is turned off, RA is substituted for STIME2, and the CYCLE flag is set to 0 at the bottom of FIG. This time, the CYCLE flag is 0, so proceed to the F side on the right, turn off the radio wave, check the RA, and then RA
It goes through a small loop that returns to the unit time elapsed check until is zero. When RA becomes 0, the operation proceeds to the T side and returns to the next step after the start. In this way, PTIME2 and STIME2 are alternately repeated, and when the temperature reaches TEMP2,
Go to B.

FIG. 7 is the latter half of the program flow chart, which has exactly the same structure as that after the start of FIG. 6, except that each 2 of ON2, OFF2, PTIME2, STIME2 and TEMP2 is replaced by 1. It is only that the T side of the temperature check is finished. Therefore, the description is omitted. The end means to reset all outputs from P20 to P25 to 0 and return to the state immediately after the start-up in FIG. In the program flow of FIGS. 6 and 7, the description is not complicated, and the two upper and lower magnetrons 28 and 29 are operated at the same time. However, one of them is actually operated when the plus side waveform of the AC waveform is used. , It is a spark prevention to operate two magnetrons at the same time by using the method of operating the other when the waveform is negative or operating one for a few seconds and then resting for a few seconds and then operating the other. Although there is almost no point in view of the above, and this embodiment also learns from it, it is also common knowledge to those skilled in the art, and even if this is omitted, there is no substitute for the essence, so priority is given to avoiding complexity.

Next, the operation of this embodiment will be described. FIG. 8 is a graph in which the horizontal axis represents time, the vertical axis represents temperature, and the vertical axis partially represents high frequency irradiation intensity. In the above description of the program flow chart, to avoid complication, only the portion related to the scope of the claims of the present invention is limited, but generally, in a high frequency heating device such as a microwave oven, in addition to the automatic cooking function, high output (high frequency continuous irradiation) and low It is common knowledge that it has an operation function with output (high frequency intermittent irradiation),
The same applies to the present embodiment, and detailed description thereof will be omitted. Now, the vacuum-packed food such as pork is placed on the food placing table 2 and heated at an appropriate low output. At this time, the temperature sensitive element of the optical fiber type thermometer is inserted in the most easily heated portion and the least heated portion of the pork, and the temperature of that portion is monitored. At the same time, the voltage at the IN1, 2 and 3 terminals of the microprocessor 60 is also monitored.

In FIG. 8, the two-dot chain line shows the temperature of the portion of the pork most easily heated, the one-dot chain line shows the temperature of the least heated portion, and the solid line shows the thermistor 4. It is the highest value of 5 or 6 (temperature conversion of the IN1, 2 and 3 terminal voltages). Until the temperature indicated by the chain double-dashed line reaches T3 (for example, 50 ° C.), the temperature is kept constant (for example, high frequency irradiation of ON2 for 3 seconds and stop of OFF2 for 3 seconds are repeated alternately). Up to (for example, 65 ° C.), this low output is operated for the above-mentioned PTIME for 2 hours and the high frequency is completely stopped for STIME for 2 hours. The maximum temperature among the values of the thermistor 4, 5 or 6 when the T1 temperature is reached is TEMP2. Similarly, the temperature when reaching T3 is TEMP3.

After reaching T1, the high frequency irradiation is completely stopped,
Wait until the temperature of the chain double-dashed line drops to T2 (for example, 64 ° C.). Record the time from T1 to T2. T2
Once again, the temperature is kept constant (for example, high frequency irradiation for 3 seconds is turned on for 1 second, and then stopped for 3 seconds for off 1 is repeated alternately).
Also record the time to rise to 1. The cycle between T1 and T2 is repeated alternately and waits until the temperature of the portion that is most difficult to be heated, which is indicated by the alternate long and short dash line, becomes T2. The maximum temperature of the thermistor 4, 5 or 6 when reaching T2 is TEM
Let P1. In addition, the average of the time from T1 to T2 is S
The average time of heating from TIME1, T2 to T1 is PT
IME1.

Using the obtained constants, the high-frequency heating apparatus of this embodiment is operated again using pork of the same shape and material. Use a fiber optic thermometer to monitor the pork temperature again. If the temperature of the most easily heated portion can be reproduced without exceeding T1, the constant will be used as it is for future pork heating. If it exceeds T1, the value of the constant is slightly modified and the pork is heated again. Generally, it is desirable that the temperature gradually increases as shown by the broken line. Also, using these constants, without using an optical fiber thermometer, that is, heating the pork without penetrating the temperature sensing element into the vacuum pack, measuring the temperature of each part after heating, and if there is a part exceeding 65 ° C Correct the constants again and check again.

As an example, the constants when 170 g of pork is cooked at 65 ° C. are introduced. TEMP1 = 59 ° C., TE
MP2 = 44 ° C, ON2 = 3 seconds, OFF2 = 3 seconds, PT
IME2 = 18 seconds, STIME2 = 18 seconds, ON1 = 3
Seconds, OFF1 = 3 seconds, PTIME1 = 12 seconds, STIM
E1 = 33 seconds.

Although the operation has been described above, the difference from the prior art will be mainly described for the purpose of arranging the gist of the present invention. Conventionally, it was impossible to cook with a finishing temperature range of 1 ° C. using a high-frequency heating device such as a microwave oven. It is generally said that if a microwave oven is used, the food is heated from the inside, but as is well known to those skilled in the art, the strength of the radio wave is halved at a depth called the half depth determined by the material, and the radio wave is emitted inside the food. Will be significantly weakened. Since there is a difference in the strength of the applied radio waves from the beginning, it can be said that there will be a difference in the heating results. It is easy to understand that the temperature difference between the highest temperature part and the lowest temperature part increases as the strength of the applied radio wave increases, so it is easy to give the illusion that uniform heating can be achieved if the radio wave strength is weakened. . However, it is widely experienced by those skilled in the art that things that cannot actually occur. From an ironic point of view, the fact that numerous ideas for uniform heating have been filed as patents or new patents can be said to support the fact that uniform heating has not been achieved.

On the other hand, in the case of a hot water bath or a steam oven which achieves heating within the maximum and minimum temperature range of 1 ° C., the inside is heated by heat conduction from a heat source around the food. The present invention positively incorporates the heat conduction from the periphery of the food to the inside during the high frequency irradiation stop period, and as a result, achieves the heating within the maximum and minimum temperature range of 1 ° C. Explaining in this way, the technique of stopping the high frequency irradiation and achieving uniform heating has been widely used, and it can be argued that there is no difference from the gist of the present invention. However, there are three essential differences between these conventional techniques and the present invention, the first is the purpose, the second is the resulting difference in time or frequency of use, and the third is the temperature detection means and its output. It is the handling of values. First of all, the high-frequency intermittent irradiation in the prior art is directed to uniform heating by weakening the above-mentioned radio wave intensity. Therefore, in order to reduce the power, for example, in the model for export to North America, the power of 10 steps is used. Values are produced up to selectable ones. 10 kinds of ratios of ON (irradiate high frequency) time and OFF (stop) time are provided, and power is adjusted in 10 steps by alternately repeating ON and OFF.

Aside from this, a method called standing time, in which the high frequency irradiation source is not operated at all and the time for leaving the food in the heating chamber simply is set after the end of the normal heating time, is also adopted in the North American export model. Was there. It can be argued that this is exactly equivalent to STIME 1 or 2 of the present invention. However, the purpose of this standing time is vague relaxation of non-uniformity caused by heating, and is only one-time use, and in the positive use as in the present invention or quantitative use in relation to the maximum and minimum temperature of food, Absent. That is, in the present invention, STIME1 is used to lower the temperature of the highest temperature portion of the food product by high frequency heating from the finishing temperature T1 to a constant temperature T2 which is lower by about 1 ° C. This is the first difference in purpose. Accordingly, in terms of the second time and frequency, the conventional standing time is once immediately after the end of heating, whereas STIME 1 or 2 of the present invention is repeatedly used alternately with PTIME 1 or 2 to detect food surface temperature. It is used many times until the output of the means reaches TEMP1.

The output of the third temperature detecting means, particularly the surface temperature, has been handled in the prior art on the premise that an accurate value can be obtained. For example, JP-A-54-
In the case of 7641, when the surface temperature reaches 5 ° C, radio wave irradiation is stopped
A technique is disclosed in which the temperature is lowered to 0 ° C. and then re-input, and this process is repeated alternately. However, detection of a surface temperature of 5 ° C. or 0 ° C. is practically impossible. This is because foods heated by high frequency generally have a non-uniform temperature distribution, and the temperature value cannot be limited. Moreover, even if the average value is limited, it cannot be grasped. For example, assume that an infrared thermometer is used. As is well known, an infrared thermometer has a viewing angle, and all radiant energy is output from within this viewing angle. It is practically impossible for the size of the food and the size of the viewing angle to be exactly the same, so either a part of the food is not included in the field of view, or radiation other than the food is included in the field of view. is there,
Either way, an error will occur, and if the size or shape of the food changes, the error will also change significantly.

On the other hand, the present invention presupposes this error,
An optical fiber thermometer is used to quantitatively ascertain the error that is a function of the type and shape of food, and control is performed with a value that is corrected accordingly. This is the third difference. Even if an infrared thermometer is used, it is necessary to use a food placing table with a thermistor as in this embodiment, depending on the temperature of the food or the type, shape, weight and finishing temperature of the food with the optical fiber thermometer. Obtaining correlation is an essential requirement. Further, when a food placing table made of a metal rod-shaped body is used as in this example, it is possible that the portion of the food which comes into contact with the rod-shaped body is overheated, but the high frequency irradiation time is short and the time for heat conduction is sufficient. Perhaps, pork did not have such an overheated part.

PTIME1, STIME1, etc. are experimentally determined, but ON1 and 2, OFF1 and 2, PT
IME2, STIME2, etc. can be set arbitrarily. However, it is limited to a numerical value within a narrow range depending on the type, shape, weight and finishing temperature of the food. Outside this range, the highest temperature portion of the food may exceed the finishing temperature T1, or the lowest temperature portion of the food may not rise in temperature for any long time. It is used after conducting preliminary experiments many times for each food to be heated and determining these constants. Therefore, not only the length and frequency of use differ from the conventional OFF time and standing time,
The fact that the constants that are a function of the food to be heated and the finishing temperature thereof are adopted is largely different, and the determination of these constants is greatly facilitated by using the optical fiber thermometer.

The main points of the present application are summarized as follows: (1) There is a means for detecting the temperature of the food surface. (1a) The detected output correlates with the output of the optical fiber thermometer. (2) Two values are set for the output value of the food surface temperature detecting means. (2a) One of them, TEMP2, is the value at the time when the highest temperature portion of the food measured by the optical fiber thermometer reaches the finishing temperature T1, and the other one TEMP1 is the lowest temperature portion of the food measured by the optical fiber thermometer. It is a value at the time when the temperature reaches T2 temperature which is lower than T1 by about 1 ° C. (3) The output of the food surface temperature detection means is TEMP2 or more T
When EMP1 or less, PTIME1 that alternately repeats high frequency irradiation for 1 hour and stop for 1 hour at a predetermined time ratio, and STIME that completely stops high frequency irradiation
Set two times with 1 and repeat this alternately. It should be noted that alternating high-frequency irradiation for ON 1 hour and high-frequency irradiation for OFF 1 hour are alternately repeated is referred to as high-frequency irradiation with POWER1 power. (3a) PTIME1 is the time when the maximum food temperature portion measured by the optical fiber thermometer rises from T2 to T1, and STIME1 is the time when it falls from T1 to T2. (4) Above numerical values TEMP1, TEMP2, STIME
1, PTIME1 and POWER1 (or ON1 and OFF1) are all functions of the type, shape, weight and finishing temperature of the food to be heated, and are determined so that the highest temperature part of the food does not exceed the finishing temperature T1 and the lowest temperature. It is determined that the temperature of the portion rises during the high frequency irradiation stop period.

The constant described in (4) above is a constant value depending on the characters in the present embodiment, but for various reasons, for example, to absorb variations in food and to achieve more stable and uniform heating. It is easily conceivable to increase or decrease the value with time for the purpose of avoiding the conflict with the present invention, but it is only within the definition of the value as a function of the food to be heated. See also STIM
It is similarly possible to insert a value such as E1 and PTIME1 which is far from the value as a function of the food to be heated once or twice during repetition.

Although the above description has been made in connection with the optical fiber thermometer, the optical fiber thermometer is not always necessary. The purpose of vacuum cooking is to heat food to a specified temperature, and the radio wave with low power for a short time heats the surrounding area of the food stronger and weakens the central part, and during the subsequent radio wave irradiation stop period, the area around the food will disappear. The purpose of the present invention is to heat the food slowly by alternately conducting heat to the food, and for example, to set a sufficiently low value TEMP5 to the finished temperature T1 of the food and set the food surface temperature detecting means. Power constant until the output becomes TEMP5
Irradiate R5 for 5 hours for PTIME, stop irradiation for 5 hours for STIME, and repeat this alternately, and confirm that the temperature of each part of the food does not exceed T1 when it reaches TEMP5, then set a temperature TEMP4 slightly higher than TEMP5, Similarly, operate with POWER4, PTIME4, and STIME4, and when the temperature reaches TEMP4, the temperature of each part of the food is again T
Make sure that it does not exceed 1. Similarly, it is possible to set higher temperatures TEMP3 and TEMP2 and gradually higher temperatures and corresponding appropriate power and time to gradually raise the food temperature and finally reach T1. In other words, even if you do not have an optical fiber thermometer, you can set the fine grain temperature and find the appropriate constant corresponding to the temperature by trial and error.
It is a technique to reduce the temperature difference between the highest temperature portion and the lowest temperature portion of the food by heating to a set temperature with the constant and gradually increasing the STIME ratio. The present invention claims the final portion thereof.

Further, in the present invention, as the food surface temperature detecting means, a food placing table in which metal rods having a temperature sensitive element such as a thermistor provided inside are arranged in parallel is used. It is also possible to use known means.
Compared to these, this example is not only inexpensive, but unlike the infrared thermometer, the difference between the output value and the food temperature does not change much depending on the size of the food, so the accurate finish temperature regardless of the size of the food. Is obtained.

In this embodiment, the operator inputs the constants before heating. However, the constants are recorded in the ROM of the microprocessor in advance, or the bar code with the name of food or a picture is input. There are also methods. However, if a specific numerical value is recorded in the ROM or the like, it cannot be changed, but if it is a method of inputting each time heating is performed as in the present invention, change or fine adjustment is easy. POWER1
1 does not consist of ON1 and OFF1 as well, the value of the phase advancing capacitor provided between the high voltage transformer 26 and the magnetron 28 of FIG. 1 is made sufficiently small to generate a predetermined low electric power, and during the PTIME 1 hour, It is also possible to use a method of continuing high-frequency irradiation. However, this method has a drawback that it is difficult to finely adjust the power value.

There are many kinds of high-frequency irradiation methods, but the method of irradiating from the center of the upper and lower surfaces of the heating chamber with the rotating antenna as in this embodiment is uniform because it is difficult to form a part which is difficult to be heated in the center of the bottom of the food. This is effective in the present invention for the purpose of temperature, and is even more effective when a metal net-like food net is used because the high-frequency power passing through the food stand is reduced.

Furthermore, the present invention is effective not only for vacuum cooking but also for thawing frozen foods, for example. That is, the finishing temperature T1 is set to about 0 ° C. or −3 ° C., and an appropriate PO serving as a function of food type, weight, shape, etc.
If WER1, PTIME1, STIME1, and TEMP1 are obtained by experiment, uniform temperature thawing can be realized.

[0038]

As described above, according to the high frequency heating apparatus of the present invention, it is possible to realize vacuum cooking by high frequency irradiation, which has been thought to be impossible in the past, and to significantly reduce energy costs.
In addition to reducing carbon dioxide emissions, it can also improve the environment of the kitchen, which was hot and humid.

[Brief description of drawings]

FIG. 1 is a combination view of an electric circuit diagram and a perspective view of the inside of a heating chamber according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the main part as seen from the side in one embodiment of the present invention.

FIG. 3 is a plan view, a side view, and a front view of the food placing table according to the embodiment of the present invention.

FIG. 4 is a perspective view of each component of the food placing table according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram of a control circuit and the same microprocessor in one embodiment of the present invention.

FIG. 6 is a first half flowchart of a program according to an embodiment of the present invention.

FIG. 7 is a second half flowchart of a program in the embodiment of the present invention.

FIG. 8 is a characteristic diagram of time and temperature showing the operation of one embodiment of the present invention.

[Explanation of symbols]

1 Heating Chamber 2 Food Placement Table 4, 5, 6 Thermistor (Food Surface Temperature Detection Means) 7 Control Circuit (Control Means) 22, 23 Triac (Means for Intermitting High Frequency Irradiation Source) 32, 33 Rotating Antenna (High Frequency Irradiation Source) ) 40 door 60 microprocessor 61 waveform shaping circuit (time measuring means) 68 keyboard (means for storing constants)

Claims (4)

[Claims] 1. A heating chamber, a door, a high frequency irradiation source, a food placing table, a food surface temperature detecting means, and a control means,
The control means includes (1) five numerical values that are functions of the type, weight, shape, and finishing temperature of the food to be heated, that is, high temperature TEMP1, low temperature TEMP2, constant high frequency power POWER1 and the above. Means for storing respective values of the irradiation duration PTIME1 of the high frequency power and STIME1 which is the time for stopping the irradiation of the high frequency;
(2) It has a time measuring means, (3) means for connecting and disconnecting the high frequency irradiation source, and (4) means for taking in the output of the food surface temperature detecting means. When the food surface temperature is TEMP2 or more and TEMP1 or less, P
A high-frequency heating device, characterized in that high-frequency irradiation is performed for 1 hour with POWME1 power, and then the operation in which no high-frequency irradiation is continued for 1 hour is alternately repeated. 2. The high frequency heating apparatus according to claim 1, wherein a temperature sensitive element such as a thermistor is provided inside as the surface temperature detecting means, and a food placing table composed of a plurality of metal rod-shaped bodies parallel to each other is used. 3. The high frequency heating apparatus according to claim 1, wherein a high frequency irradiation source is provided at the center of the upper surface and the lower surface of the heating chamber. 4. A heating chamber, a door, a high frequency irradiation source, a food placing table, a food surface temperature detecting means, and a control means,
The control means includes (1) five numerical values that are functions of the type, weight, shape, and finishing temperature of the food to be heated, at least two temperatures, TEMP1 that is a high temperature, and T that is a low temperature.
Means for storing respective values of EMP2, constant high frequency power POWER1 and irradiation time PTIME1 of the high frequency power, and STIME1 which is a time for stopping high frequency irradiation; (2) time measuring means; and (3) It has means for connecting and disconnecting the high frequency irradiation source and (4) means for taking in the output of the food surface temperature detecting means. When the food surface temperature is TEMP2 or more and TEMP1 or less, P
In a high-frequency heating device that repeats the operation of irradiating PTIME for 1 hour with OWER1 power and then continuing the state without high-frequency irradiation for STIME for 1 hour, using an optical fiber type temperature measuring device having at least two temperature sensitive elements, an optical fiber type Insert one temperature sensitive element of the temperature measuring device into the hottest part of the food, insert the other temperature sensitive element into the coldest part of the food, irradiate the food with high frequency at constant power by manual operation, etc. After the output of the temperature sensitive element inserted in the highest temperature part of the temperature reaches the finishing temperature T1 of the food, the output value of the surface temperature detecting means is determined to be TEMP2, and then the high frequency irradiation is stopped to stop the temperature of the food. When the temperature drops to T2, which is a constant temperature lower than the finishing temperature by about 1 ℃, it is irradiated with high frequency by POWER1 power, and the highest temperature part of the food is reused. When the output of the inserted temperature sensitive element reaches T1, the operation of stopping the high frequency irradiation and waiting until it decreases to T2 is repeated, and the output of the temperature sensitive element inserted in the lowest temperature part of the food reaches T2. The output of the food surface temperature detecting means at that time is determined to be TEMP1, and the substantial average value of each time when the temperature rises a plurality of times from T2 to T1 is PTI.
ME1 and the average value of each time when it goes down from T1 to T2 is STIME1 and these POWER
1, PTIME1, STIME1, TEMP1, TEM
A high-frequency heating method, wherein P2 is stored in the high-frequency heating device and then operated.