JPH1096517A - Microwave cooker using thermopile sensor and defrosting method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embody an optimum defrosting constantly by controlling the output of magnetron with a measured temperature of one thermopile sensor and determining the variation range of the measured temperature for one turn of a turn table in an initial period and deciding the point of the end of defreezing with consideration given to the degree of eccentricity of a load. SOLUTION: When a defreezing key is input, for a time which adds a single turning time of an initial turn table 9 to a defreezing response time which is required until a motor 8 turns in normal mode, a magnetron 7 is turned off while an initial period temperature of a foodstuff is detected by means of a thermosensor 2. Then this temperature is filtered, thereby computing a maximum value and a minimum value for the on/off cycle of the magnetron 7. Then in the case when the on/off cycle of the magnetron 7 has elapsed, the maximum filtered value is determined. In the case when a variable value of the filtered value is increased, additional defreezing time is computed so as to determine the defreezing end time and the on time ratio of the magnetron is computed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven using a thermopile sensor and a method for thawing the same, and more particularly to detecting a surface temperature of food and drink using a thermopile sensor. A microwave oven using a thermopile sensor that can improve thawing and reduce thawing time by adjusting the output of the magnetron according to the surface temperature, size, and weight of the food and drink to determine the thawing end point in the optimal thawing state And its thawing method.

[0002]

2. Description of the Related Art In a conventional microwave oven, as shown in FIG. 25, a turntable 30 is provided at the center of a heating chamber 20 for placing a frozen food 31 thereon, and a waveguide for thawing the frozen food 31 is provided. A magnetron 27 serving as a heating source for supplying microwaves through the heater; a turntable motor 29 for rotating the turntable 30;
A thermopile sensor 21 which is disposed on the upper side of one side and detects the temperature of the frozen food, converts the temperature into a voltage corresponding to the temperature and outputs the voltage, and a heating chamber 20 when the frozen food 31 is thawed.
, A cooling fan 28 for cooling the magnetron 27 so that the magnetron 27 is not overheated, and a thawing time determined by receiving the voltage output from the thermopile sensor 21 and necessary according to the determined thawing time. A microcomputer 22 for outputting a control signal for controlling various parts,
Control switches 23 to turn on / off the interior lamp 32, the magnetron 27, the cooling fan 28, and the turntable motor 29 according to control signals from the microcomputer 22.
26. In this case, a weight sensor (not shown) that is connected to the turntable motor and detects the weight of the frozen food is located.

The thawing process of the frozen food of the conventional microwave oven configured as described above will be described with reference to FIGS. First, after the frozen food 31 is placed on the turntable 30 of the heating chamber 20 and a defrosting switch of a key unit (not shown) is selected, the microcomputer 22 recognizes that the defrosting function is performed and the operation process shown in FIG. I do.

[0004] Next, the microcomputer 22
In order to perform thawing, first, when the control switches 23 to 26 for driving the magnetron 27, the cooling fan 28, the turntable motor 29, and the interior lamp 32 are turned on (S1), the turntable 30 is turned by the turntable motor 29. At this time, the microcomputer 22 measures the weight of the frozen food 31 using the weight sensor connected to the turntable motor 29 side (S2), and thereafter, the rotation time (Q2) of the turntable 30 is changed. ) Is calculated as follows using one cycle time (TO) of the commercial power supply and the coefficient (P) of the turntable motor 29 (S3).

Q = (1 / TO) / P Here, it is assumed that P = 5, TO = 20 msec and Q = 10 seconds. Thereafter, when a predetermined time (250 msec) has elapsed (S4), the microcomputer 22 controls the outputs (0 watts, 300 watts, and 600 watts) of the magnetron 27 so as to be as shown in FIG. 26 (S5), and such control is performed. When the magnetron 27 is turned off by (S)
6), receiving the voltage output from the thermopile sensor 21 and calculating a voltage V proportional to the temperature of the frozen food 31 as follows (S7).

V = R × (V1-V3) + S × V2 + T Here, V1 is a voltage obtained by amplifying the output of the thermopile sensor 21, V2 is a voltage of the thermistor, V3 is a reference voltage of the thermopile sensor, and R, S, T Indicates a constant. Next, after checking whether or not Q seconds of one rotation time of the turntable 30 has elapsed (S8), if Q seconds of one rotation time of the turntable 30 has elapsed, the weight W of the frozen food 31 is obtained. (S9), and when the weight W of the frozen food 31 during one rotation time of the turntable 30 is measured with the magnetron 27 turned off, FIG.
In step 6, the time T for generating the output of the magnetron 27 of 600 watts is calculated as follows (S10).

After T1 = 0.06 × W, the time TLmax (hereinafter abbreviated as the maximum thawing end time) at which the thermopile sensor 21 unconditionally ends thawing without detecting the end of thawing, and the thermopile sensor 21
Is the time TLmin (hereinafter abbreviated as the minimum thawing end time) for which the heating of the magnetron is interrupted even when the thawing end is detected.
(S11).

TLmax = 2 × W TLmin = 1 × W As described above, the maximum and minimum decompression end points (TLmax
(x, TLmin), the process returns to step S4 and proceeds to step S8. Then, in step S8, two rotations (Q seconds) of the turntable 30 do not elapse, and
When the rotation time (Q seconds) after the first time has elapsed (S1
2), thawing progress time minimum thawing end point (TLmin)
It is checked whether or not it is between the maximum decompression end time (TLmax) and the maximum decompression end time (TLmax) (S12, S13). As a result, the decompression progress time is determined by the minimum decompression end time (TLmin) and the maximum decompression end time (TLmax). If the time has elapsed, it is determined that the decompression is completed. However, if the minimum decompression end time (TLmin) has elapsed and the maximum decompression end time (TLmax) has not elapsed, the L value and the M value are calculated as follows (S15, S1).
6).

L = min / ave M = dV / dt Here, min is the minimum voltage obtained during one rotation of the turntable 30, ave is the average value, and dv / dt is the differential value of the voltage V with respect to time. That is, the L value is an evaluation value for the amount of vibration of the voltage data measured during one turn of the turntable 30, and the M value is a value for determining whether or not the temperature of the food rises sharply. In this case, the normal L value is as shown in FIG.
As shown in (A), when the load is large, it becomes as shown in FIG. 28 (B). In addition, it enters the infrared field of view of the extremely high and low temperature parts, that is, the small load. The case is as shown in FIG.

Therefore, in step S15, the L value has passed the minimum decompression end point TLmin and has reached the maximum decompression end point (TLm).
ax) is compared with a reference value of 0.094 for judging the degree of vibration of the voltage data before the time elapses, and as a result of the comparison, when the L value is smaller than the reference value of 0.094, FIG.
As shown in (C), since the load falls within the infrared visual field, it is determined that the thawing is completed.
When it is larger than the reference value of 94, FIGS. 28 (A) and (B)
As shown in (2), since the load corresponds to an appropriate load or a large load, the M value is compared with a reference value of 10 to select one of the two loads (S16). As a result of the comparison, when the M value is smaller than the reference value of 10, it is determined that the load does not easily increase the temperature of the center of gravity of the food, and the thawing is ended when the maximum thawing end time (TLmax) is reached. When the M value is larger than the reference value of 10, the load is determined to be an appropriate load that can raise the center temperature of the food, and the thawing is determined to be completed.

As described above, in the method of thawing frozen food, the surface temperature of the food 31 is measured by using the thermopile sensor 21, and the weight W of the frozen food is measured by using the weight sensor, and the time calculated by the calculation is as follows. The output of the magnetron 27 is controlled to determine the end point of the thawing. At this time, the output of the magnetron 27 is a time T1 = 0.06 W set in proportion to the weight W of the frozen food measured by the weight sensor.
During this time, it is heated to a high output (600 watts), and thereafter a constant output (300 watts) is applied to the turntable 3.
It is controlled by a method of turning on for one rotation time (Q seconds) of 0 and turning off again for one rotation time (Q seconds) of the turntable 30.

[0012]

However, in such a conventional microwave oven using a thermopile sensor and its thawing method, when the output of the magnetron is controlled, it is necessary to obtain the initial heating time T1 for high power. Since the use of the weight sensor increases the cost, when a large load is thawed at a constant output (300 watts) after the time T1, a long time is required until the decompression end time, and when the load is small, the load is large. On the other hand, since the output of the magnetron is strong, there is a problem that a partially boiled portion is formed or the inside of the load is extracted outside by over-thawing.

Further, when the load is eccentric at the center of the turntable, there is a problem that the magnitude of the load is erroneously determined and a malfunction occurs. In order to solve such a problem, an object of the present invention is to read data of a thermopile sensor and continuously control the output of a magnetron in accordance with the read data, so as to optimize the output regardless of the size and weight of food and drink. To provide a microwave oven using a thermopile sensor capable of controlling the output of a magnetron and a method for thawing the microwave oven.

Another object of the present invention is to determine the optimal thawing end point by determining the phase transition time when the surface of the food becomes ice-water from the data of the thermopile sensor so that the thawing becomes good. Another object of the present invention is to provide a microwave oven using a thermopile sensor capable of completing thawing within a short time, and a method of thawing the same. Still another object of the present invention is to use the ratio of the on-time of the magnetron to a value that changes according to the temperature oscillation width and the eccentricity of the load measured during one rotation time of the initial turntable. It is an object of the present invention to provide a microwave oven using a thermopile sensor capable of performing optimal thawing by determining the end point of thawing and a method of thawing the microwave oven.

[0015]

In order to achieve the above object, in a microwave oven using a thermopile sensor according to the present invention, infrared rays radiated from a load are collected and correspond to the collected infrared rays. An amplifier for amplifying an output voltage from a thermopile sensor module for outputting a voltage, an analog / digital converter for converting an analog voltage signal of the amplifier into a digital voltage signal, and a digital signal for the analog / digital converter A microcomputer that controls an on / off switch of the magnetron to control energy supplied from the magnetron to the heating chamber by executing an algorithm of a built-in thawing method, wherein the microcomputer includes:
A voltage signal sampling unit that reads a digital signal output from the analog / digital conversion unit at predetermined time intervals;
A voltage signal for converting the sampled voltage signal into a temperature, removing noise included in the converted temperature, and calculating a maximum value, a minimum value, and an average value of the temperature during an on / off cycle time of the magnetron. The optimum magnetron on / off time is calculated for each on / off cycle of the magnetron using the processing unit and the maximum value, minimum value, and average value of the temperatures, and the thawing end time is determined so as to end the thawing at the optimum time. And determine
A magnetron on / off time calculation and abnormal phenomenon determination unit for detecting an abnormal state of food and drink, and a control signal is output to a magnetron on / off switch based on the output of the magnetron on / off time calculation and abnormal phenomenon determination unit to output the magnetron. And a magnetron on / off switch control unit for controlling the output.

In the method for thawing a microwave oven using a thermopile sensor according to the present invention, one rotation time of the initial turntable at the time of input of a thawing key and a thawing response time until the turntable motor rotates normally are determined. The magnetron is turned off for the added time, a first step of sensing the initial temperature of the food and drink, and a temperature (T) sensed in the first step is filtered using a digital filter, and the filtered A second step of calculating a maximum value, a minimum value, and an average value during the magnetron on / off period for the temperature, and determining whether the magnetron on / off period has elapsed. , Second
A third step of repeating the steps and, if elapsed, filtering the highest value to calculate a filtered value;
Calculate the change value of the filtering value in the third stage,
A fourth step of determining whether or not the increase has occurred, and when the change value has increased in the fourth step, an additional thawing time is calculated to determine a thawing end time point, and then a magnetron-on time ratio is calculated.
If the change value does not increase, the fifth step of immediately calculating the magnetron-on time ratio, and the decompression algorithm is abnormal using the magnetron-on time ratio calculated in the fifth step, the average value, and the elapsed time so far. A sixth step of judging whether or not to perform the operation, and when it is determined that the state is abnormal, the magnetron is turned off to end the thawing, and when it is determined that the state is not abnormal, the procedure returns to the first step and repeats. And the seventh step are sequentially performed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In the microwave oven using the thermopile sensor according to the present invention, as shown in FIG. 1 and FIG. 11, the infrared rays generated from the food and drink 10 and the infrared rays generated from the turntable 9 are collected by the light collecting means (not shown). Integrated thermopile sensors (hereinafter abbreviated as thermosensor modules) 2 for generating corresponding voltages, respectively
An amplifier 3 for amplifying the output voltage of the thermosensor module 2 to a predetermined level and outputting the same, an analog / digital converter 4 for converting a voltage signal of the amplifier 3 into a digital voltage signal and outputting the digital voltage signal, The voltage signal of the analog / digital converter 4 is received and processed, and the algorithm for the decompression method built in the analog / digital converter 4 is executed to control the magnetron on / off switch 6 to supply the food and drink 10 in the heating chamber 1 from the magnetron 7. And a microcomputer 5 for controlling the energy to be supplied, wherein the microcomputer 5 reads a digital signal output from the analog / digital converter 3 every predetermined time ts. 51, the sampled voltage signal is converted into a temperature T, and the converted temperature T
And the maximum value Tmax and the minimum value Tmi of the temperature during the magnetron on / off period tm.
n and a voltage signal processing unit (52) for calculating and outputting an average value Tmean, and a maximum value Tmax, a minimum value Tmin, and an average value Tmen for the temperature T, and a magnetron on / off value.
A temperature data sampling unit 53 that samples and outputs the data every off period, and uses the data sampled by the temperature data sampling unit 53 to turn on / off the magnetron.
Calculate the optimal magnetron on / off time for each off cycle, determine the thawing end time so that thawing ends at the optimal time, determine whether the food is abnormal or not, A control signal is output to the magnetron on / off switch 6 based on the output of the magnetron-on time ratio calculation / abnormal phenomenon determination unit 54 and the output of the magnetron-on time ratio calculation / abnormal phenomenon determination unit 54 that terminates the thawing at a certain time. And a magnetron on / off switch control unit 55 for controlling the output.

The voltage signal processing section 52 has a predetermined time ts
An algorithm for converting a voltage signal sampled every time to a temperature T, a digital filter algorithm for removing noise included in the temperature T, and a maximum value for obtaining a maximum value Tmax of the temperature during the magnetron on / off period tm Calculation algorithm and magnetron on / off period t
The processing is performed using a minimum value calculation algorithm for obtaining the minimum value Tmin of the temperature for m hours and an average value calculation algorithm for obtaining the average value Tmean of the temperature for the magnetron on / off period tm time.

In the method for decompressing a microwave oven using the thermopile sensor according to the present invention, as shown in FIG.
During the time obtained by adding the rotation time and the rotation response time until the turntable motor rotates normally, a first step of turning off the magnetron and detecting the initial temperature T of the food and drink, and the first step is detected. The temperature T is filtered using a digital filter to the temperature Tf, and the filtered temperature Tf has the maximum value Tmax, the minimum value Tmin, and the average value Tm during the magnetron on / off period.
The second step of calculating each of the values of “an” and “magnetron on /
Determining whether the off period has elapsed, and if not, repeating the first and second steps; otherwise, filtering the maximum value Tmax and calculating a filtered value Tmaxf And the change value Δ of the filtered value Tmaxf of the maximum value Tmax in the third stage.
A fourth step of calculating Tmaxf to determine whether it has increased, and if the change value ΔTmaxf has increased in the fourth step, an additional thawing time ta is calculated to determine the thawing end time, and then the magnetron-on time ratio And the change value ΔT
If maxf has not increased, a fifth step of immediately calculating the magnetron-on time ratio, the magnetron-on time ratio calculated in the fifth step, and the average value Tmea
a sixth step of determining whether or not the thawing algorithm performs an abnormal operation and determining an abnormal state of the food or drink by using the n and the elapsed time so far; and a magnetron when determining in the sixth step that the state is abnormal. Is turned off, the thawing is completed, and if it is determined that the state is not abnormal, the seventh step of returning to the first step and repeating is sequentially performed.

At this time, whether or not the maximum value Tmax in the fourth step can be increased with respect to the change value ΔTmaxf of the filtering value Tmaxf is determined when the time tr elapsed to the present time is smaller than three magnetron on / off cycles (3 × tm). Is ΔTmaxf (tr) of the current ΔTmaxf value and t
ΔTmaxf (tr−t
m), ΔTmaxf (tr) is ΔTm
When it is larger than axf (tr-tm), it is determined that ΔTmaxf has increased, and when it is smaller, it is determined that ΔTmaxf has not increased.

In the fourth step, whether the maximum value Tmax increases with respect to the change value ΔTmaxf of the filtering value Tmaxf is determined when the time tr elapsed to the present time is longer than three magnetron on / off cycles (3 × tm). ΔTmaxf (tr) of current ΔTmaxf value and ΔTma of ΔTmaxf value before tm time and before 2 × tm time
xf (tr−tm) and ΔTmaxf (tr−2 × t
m) and ΔTmaxf (tr) is ΔTm
af (tr−tm) and ΔTmaxf
When it is larger than (tr−2 × tm) + δ (positive number larger than 0), it is determined that ΔTmaxf increases, and it is determined that it does not increase in other cases.

In another embodiment of the method of thawing a microwave oven using a thermopile sensor according to the present invention, as shown in FIG. A first step of calculating, a second step of calculating a value Kd to be converted according to the degree of eccentricity corresponding to the vibration width calculated in the first step, and an initial temperature from the current temperature of the load for each magnetron on / off cycle tm. A third step of multiplying a relative temperature value obtained by subtracting the above and a different weight value to obtain a magnetron-on time ratio P;
The value obtained by subtracting the value obtained by multiplying the load temperature change measured at each magnetron on / off cycle tm by the value Kd from the magnetron on time P obtained in the step is a specific constant value D.
When the value is smaller than r, the fourth step of terminating the decompression is sequentially performed.

The operation of the present invention thus configured will be described. First, when the user places the food 10 on the turntable 9 of the heating chamber 1 and then presses a decompression key (not shown),
The microcomputer 5 recognizes this and outputs a drive signal to the turntable motor 8 and turns on the magnetron on / off switch 5. Next, the turntable 9 is rotated by the turntable 8, and the magnetron 7 is rotated.
The microwaves are emitted to the food and drink in the heating chamber by the drive of, and the food and drink 10 starts to thaw.

Next, when the condensing means of the thermosensor module 2 condenses the infrared rays radiated while the food and drink 10 is thawed and sends it to the thermopile sensor, the thermopile sensor corresponds to the condensed infrared rays. And outputs it to the amplifier 3. In this case, the condensing means comprises a convex lens and a concave reflecting mirror, which makes the viewing angle of the thermopile sensor narrow as necessary and increases the output voltage of the thermopile sensor.

Here, the thermosensor module 2
Is located obliquely on the upper side of one side of the heating chamber 1 so as to face the turntable 9 as shown in FIG. 1, or is separated from the center of the heating chamber 1 by a predetermined distance as shown in FIG. The temperature of the center and side portions of the turntable 9 is measured without measuring only the temperature of the central portion of the turntable 9. At this time, the relationship between the size of the food and drink located on the turntable 9 and the field of view of the thermosensor module 2 is shown in FIG. 2 when the thermosensor module 2 is located on the side of the heating chamber 1. As shown in FIG. 4, when the thermosensor module 2 is located at the center of the heating chamber. Such a viewing angle will be described later.

Next, the amplifying unit 3 amplifies the minute output voltage of the thermosensor module 2 to a predetermined level so as to be processed by the A / D converter 4 and outputs the amplified voltage to the A / D converter 4. The analog / digital converter 4 converts the analog voltage signal corresponding to the temperature of the food and drink amplified to a predetermined level into digital voltage data and outputs the digital voltage data to the microcomputer 5.

Next, the microcomputer 5 processes the digital voltage data, performs an algorithm relating to a decompression method incorporated therein using the processed voltage data, determines a decompression end time point, and The magnetron on / off switch 6 is controlled according to the execution. Here, the magnetron on / off switch 6 is constituted by a relay or a transistor.

Thereafter, the magnetron 7 of the food heating means is driven by the magnetron on / off switch 6 to generate microwaves in the food 10 in the heating chamber 1, and the turntable motor 8 has a predetermined time interval. Then, the food and drink 10 are heated uniformly by rotating the turntable 9. At this time, when the frozen food is heated by the heat source, the change in the surface temperature of the food and drink has a characteristic as shown in FIG. That is, the change in the surface temperature of food and drink is shown in FIG.
As shown in (A), two inflection points appear, and until the first inflection point appears, it indicates that the surface of the food and drink is still in an ice state and the surface temperature rises. In addition, from the first inflection point to the second inflection point, a state is shown in which ice at 0 ° C. changes to water at 0 ° C. At this time, the energy supplied by the magnetron 7 of the heat source is changed to water at 0 ° C. There is no change in food and drink surface temperature, which is consumed by the changed phase transition. In addition, the surface temperature of the food that is brought into a water state from the second inflection point is continuously heated by the heat source. Thereafter, when the heating is continued, a phase transition in which water changes to water vapor appears, and the surface temperature of the food and drink stops at 100 ° C. at this time.

The surface temperature change rate of food and drink is shown in FIG.
As shown in (B), the temperature change rate decreases until the phase transition occurs, and there is no temperature change at the time when the phase transition occurs, so the temperature change rate is 0, and thereafter, the temperature change rate increases. . Therefore, when the frozen food is thawed, the completion time of the thaw may be determined based on the time when the surface of the food and drink undergoes the phase transition from ice to water. At this time, it can be seen that the time point at which the phase transition from ice to water ends is the time point at which the temperature change rate becomes greater than zero.

However, when the surface temperature of food and drink is measured by a thermopile sensor of an actual microwave oven, a temperature change as shown in FIGS. 6 and 7 appears rather than a temperature change as shown in FIG. That is, when the phase transition proceeds from ice to water, there is ideally no temperature change. 6 and 7 that the measured temperature increases during the phase transition. This is a phenomenon that appears based on the viewing angle of the thermopile sensor and the size of food and drink, and will be described below with reference to FIGS.

First, FIG. 2 shows the relationship between the range of the visual field and the size of food and drink when the thermopile sensor is located on the upper side of one side of the heating chamber 1. FIG. 2 (A) shows the size of food and drink. Only infrared rays emitted from the surface of the food and drink enter the thermopile sensor, and the change in the surface temperature of the food and drink at this time has the characteristics shown in FIG. On the other hand, in FIG. 2 (B), the size of food and drink is small,
The infrared radiation radiated from the turntable 9 together with the infrared radiation radiated from the food is also input to the thermopile sensor, so that the change in the surface temperature of the food exhibits characteristics as shown in FIGS.

FIG. 4 shows the relationship between the visual field range and the size of food and drink when the thermopile sensor is located above the heating chamber 1. In FIG. 4 (A), the size of the food and drink is sufficiently large. Only infrared rays radiated from the surface are incident on the thermopile sensor, and the change in the surface temperature of the food and drink at this time has a characteristic as shown in FIG. On the other hand, in FIG. 4B, the size of the food is small, and the infrared emitted from the turntable is also input to the thermopile sensor together with the infrared emitted from the surface of the food, and the surface temperature of the food at this time is measured. The changes represent features as shown in FIGS.

The size of the food is indirectly grasped from the surface temperature of the food based on the relationship between the thermopile sensor and the size of the food described above, and the output of the magnetron 7 is appropriately adjusted according to the size of the food. The problem that the frozen food is partially overthawed or not thawed can be solved. As can be seen from FIGS. 6 and 7, at the time when the phase transition from ice to water occurs, the measured temperature of the small food is higher than that of the large food. In addition, in the case of large and small foods having the same surface temperature of food and drink, the heating time of the magnetron should be longer for large food and drink than for small food, but the measured temperature of the thermopile sensor of the present invention is used. The optimal magnetron output can be determined according to the size of the food and drink.

Hereinafter, a process for determining an optimum magnetron output will be described. Assuming that the magnetron-on time ratio is P and the surface temperature of food and drink is T, the magnetron-on time ratio P is expressed by the following equation. P = f (T) (1) Here, assuming that the magnetron on time is ton and the magnetron off time is off, P = tOn / (to
n + off), and f (T) can be linear as a function of T or non-linear. or,
Assume that the magnetron on / off period tm is constant.

Therefore, as can be seen from the above equation (1),
Since the magnetron on / off period tm is constant, the temperature T is measured or calculated at every predetermined period tm, and the magnetron on time ratio P is set to the magnetron on / off period tm.
It is recalculated and changed every time. For example, in FIG. 6 and FIG. 7, when heating a small food and a large food at about 5 ° C., the magnetron-on time ratio for the large food is 80% (for example, when the magnetron is turned on for 8 seconds, the magnetron is turned off for 2 seconds). ) Is optimal, small foods can be heated to a smaller magnetron time ratio (eg, 60%) than large foods to eliminate the phenomenon of over-thaw. Therefore, the magnetron-on time ratio P is determined so as to be inversely proportional to the measured surface temperature of the food or drink.

The magnetron-on time ratio P is determined by the following first-order proportional equation. P = K1 × (Tr−T) (2) where K1 is a proportional constant and Tr is a constant. FIG. 8 shows an example of the above equation (2). Since the magnetron-on time ratio P is not larger than 1, if the temperature T is smaller than −5 ° C., P = 1. In addition, since the calculation of the magnetron-on time ratio P according to the above equation (2) uses the surface temperature of the food and drink itself measured by the thermopile sensor, it is affected by errors of individual sensors and various environmental factors. To complement this, the magnetron-on time ratio (P) is expressed in a linear form with the temperature change rate added as follows:
Can be calculated.

P = K1 × (Tr−T) + K2 × ΔT (3) where ΔT is a change value of the surface temperature of the food or drink per unit time, for example, a magnetron on / off period t
If m is kept constant at 10 seconds, the surface temperature of the food and drink changes during 10 seconds. Then, the following linear form can be used to complement the equation (3) and to consider the initial temperature of food and drink.

P = K1 × (Tr− [K2 × T + K3 (T−TO)]) = K1 × [Tr− (T−K3 × TO)] (4) where TO was measured by a thermopile sensor. The initial temperature of food and drink, (T-TO) is the difference between the subtraction temperature and the initial temperature, K2 and K3 are weight values smaller than 1, and K2
By setting a value so as to satisfy + K3 = 1, K2 can be eliminated as in equation (4).

FIG. 9 shows an example in which the magnetron on / off period tm is constant and the magnetron on / off time changes as in the above equations (1) to (4). Equations (1) to (4) are used to determine the magnetron on / off period t.
m, the ratio of the magnetron-on time was calculated, but as shown in FIG.
The magnetron on / off period tm is newly calculated according to the measured surface temperature of the food while maintaining the constant, and the magnetron on / off is controlled, or the magnetron off time off is kept constant, and the measurement is performed. The magnetron on / off period tm can be newly calculated according to the surface temperature of the food or drink to control the magnetron on / off. At this time,
The magnetron on / off period tm is calculated as follows using the magnetron on time ratio P calculated by the above equations (1) to (4).

Tm = P × ton (5) tm = toff / P−1 (6) Here, equation (5) is for the case where ton is kept constant, and equation (5) is for the case where toff is kept constant. This is the case. As explained above, when thawing frozen food in a microwave,
Using the thermopile sensor, the optimal magnetron on / off ratio P according to the optimal ending time of thawing and the amount of food and drink can be determined.

That is, since the manner in which the surface temperature of food or drink changes is directly grasped, it is possible to carry out optimal heating not to be over-thawed and unthawed, and to terminate thawing at an optimal time. Hereinafter, a method of thawing frozen food will be described with reference to FIG. 11 based on the contents described so far. The thermosensor module 2 measures the surface temperature Ts of the frozen food 10 and reads the temperature Te of the turntable according to the size of the food or drink. That is, the temperature T (= W1 × Ts + W2 × Te) obtained by integrating the surface temperature Ts of the food and drink and the temperature Te of the turntable with the respective weights W1 and W2 is read. At this time, the weights W1 and W2 change according to the size of food and drink and the internal temperature of the heating chamber 1.

Next, the thermosensor module 2 converts the voltage into a voltage V corresponding to the read temperature T and amplifies the voltage V.
The amplification unit 3 amplifies the voltage V to a predetermined level so that the voltage V is processed by the analog / digital conversion unit 4 and outputs the amplified voltage V to the analog / digital conversion unit 4. After that, the analog / digital converter 4 converts the voltage amplified to a predetermined level into a digital voltage signal and outputs it to the microcomputer 5, and the voltage signal sampling unit 51 of the microcomputer 5 outputs the digital voltage data. At a predetermined time interval ts, and outputs the sampled voltage data to the voltage signal processing unit 52.

Next, the voltage signal processing section 52 converts the sampled voltage data into a temperature, removes noise included in the converted temperature T, and obtains a maximum value for the converted temperature T, The average and minimum values are calculated and output, and the converted temperature T is processed to perform a decompression algorithm. That is, the voltage signal processing unit 52 converts the voltage signal sampled every predetermined time ts into a temperature T, a digital filter algorithm that removes noise contained in the temperature T, and a temperature during the magnetron on / off period tm. Maximum value calculation algorithm for obtaining the maximum value Tmax, minimum value calculation algorithm for obtaining the minimum value Tmin of the temperature during the magnetron on / off period tm, and averaging for obtaining the average value Tmean during the magnetron on / off period tm time The temperature data calculated by performing the value algorithm is output to the temperature data sampling unit 53. The digital filter algorithm is for removing electromagnetic wave noise included in the sampled voltage data, and is expressed by the following linear format.

Tf (t) = θ1 × Tf (t−ts) + θ2 × Tf (t−2 × ts) + ,,, + θn × Tf (t−n × ts) ω0 × T (t) + ω1 × T ( t−ts) + ,,, + ωm × T (t−ts) (7) where Tf (t) is the filtered temperature value at time t, and Tf (t−ts) is time t −ts filtered temperature value, θ1 to θn are weighted values for the filtered temperature value, T (t) is temperature value mixed with noise converted by the voltage signal sampled at time t, ω0 Ωωm is a weight value for the temperature value mixed with noise. In the microcomputer 5, θ1 to θn are all set to 0 for convenience of calculation, and ω0
Ωm can be all 1 / m values and a simple average value of the measured temperature and the current measured temperature can be obtained.

The maximum value algorithm, the minimum value algorithm, and the average value algorithm include a maximum value Tmax, a minimum value Tmin, and a temperature value Tf filtered by the digital filtering algorithm during the magnetron on / off period tm. Average value Tmea
n is obtained. When the temperature Tf thus obtained, the maximum value Tmax, the minimum value Tmin, and the average value Tmean of the temperature Tf are input from the voltage signal processing unit 52 to the temperature data sampling unit 53, the temperature data sampling unit 53 receives the maximum value Tmax. , The minimum value Tmin, and the average value Tmean, and outputs them to the magnetron-on time ratio calculation and abnormal phenomenon determination unit 54. The magnetron-on time ratio calculation and abnormal phenomenon determination unit 54 outputs the temperature Tf, the maximum value Tmax, and the minimum value Tmin. , Average Tme
After calculating an optimal magnetron on / off time using an and the above-described formulas (1) to (6), an additional thawing time ta is determined so as to end thawing at an optimal time, and abnormality of food and drink is determined. Determine whether the status is acceptable.

The magnetron-on time ratio calculation and the optimum magnetron-on time ratio calculation using the equations (1) to (6) by the magnetron-on time ratio calculation unit 54 are as follows: temperature Tf, maximum value Tmax, minimum value Tmin, average value Although all of Tmean can be used, since the minimum value Tmin is a value approximating the average value of the surface temperature of food and drink, the minimum value Tm is used.
Use in. That is, the magnetron-on time ratio is calculated by using the minimum value Tmin instead of the temperature T in Equations (1) to (6). In addition, the magnetron-on time ratio calculating and abnormal phenomenon judging section 54 determines that the thawing end time is the maximum value Tma
Use x.

FIG. 12 shows that the maximum value Tmax is most preferable for determining the ending point of the thawing. That is, FIG.
As shown in FIG. 5B, when the temperature change rate increases (FIG. 5)
In (A)), the end point of the decompression is determined from the time point at which the second inflection point occurs. In FIG. 12, the curve for the highest value shows the most inflection point. In addition, the magnetron-on time ratio calculation and abnormal phenomenon determination unit 54 calculates the additional thawing time using the time point tc at which the second inflection point occurs in the graph with respect to the temperature change, or at the time point tc the temperature of the food or drink. Tc may be used, or the predetermined time may be designated collectively at the time point tc regardless of the amount of food and drink. At this time, the time point tc at which the second inflection point occurs and the additional thawing time t using the food temperature Tc at the time point tc
a is calculated by the following linear format.

Ta = C1 × tc + C2 (8) ta = C3 × Tc + C4 (9) Here, all of C1, C2 and C3 are constant values. FIG.
3 (A) and 3 (B) show examples for the above equations (8) and (9). The magnetron-on time ratio calculation and abnormal phenomenon determination unit 54 uses the average value Tmean to determine the presence or absence of an abnormal state of food and drink. The reason is that the average value Tme
This is because an indicates the overall state of food and drink more accurately than the maximum value Tmax and the minimum value Tmin. When judging the presence or absence of such an abnormal state of food and drink, when the average value Tmean is higher than a specific temperature (for example, 20 ° C.), is the magnetron-on time ratio calculation and abnormal phenomenon judging section 54 currently in an over-thaw state? Or, it is determined that the user has pressed the thawing key in a no-load state where there is no food or drink, and a signal for turning off the magnetron 7 is output to interrupt the thawing. If the maximum value Tmax is used when judging the presence or absence of food, if the small food is positioned eccentrically at the center of the turntable 9 in summer, the maximum value Tmax is 20 during the magnetron on / off cycle tm. Exceed ° C. Therefore, there is a problem that the decompression is stopped in a state where the decompression is not performed. 13A and 13B when the minimum value Tmin is used when determining the presence or absence of an abnormal state of food and drink.
As shown in the figure, the temperature change is small in the latter half of thawing,
It is not appropriate for the minimum value Tmin to exceed 20 ° C. since a considerably long time elapses.

Further, the magnetron-on time ratio calculating and abnormal phenomenon judging section 54 judges the presence or absence of an abnormal operation of the decompression algorithm using the magnetron-on time ratio and the elapsed time up to the present time. Is output to the magnetron on / off switch control unit 55. For example, the magnetron-on time ratio is calculated as shown in FIG. 8, and when the value is smaller than 0.2, it is determined that the defrosting algorithm has failed to find an inflection point on the temperature change curve, and the defrosting is terminated. . This is because the inflection point at which the temperature change rate starts to increase is when the measured temperature is 1
Appearing at 0 ° C. or lower, the magnetron-on time ratio at 10 ° C. is 0.5 (15−10) = 0.25, so that the current value of 0.2 means that the current minimum temperature is 11 ° C.
Means that the point at which the point of inflection has already passed has elapsed. And the current magnetron on time ratio is small,
If a lot of time has passed after performing the decompression algorithm,
The thawing algorithm determines that it has failed to find an inflection point in the temperature change curve, and ends the thawing. For example, in FIG. 8, if the magnetron-on time ratio is 0.3 and five minutes have passed after the thawing algorithm was performed, the thawing is terminated.

Next, according to the magnetron-on time ratio calculated by the magnetron-on time ratio and the abnormal phenomenon determination unit 54 shown in FIG.
An on / off control signal is output to the off switch 6, and the magnetron on / off switch 6 turns on or off the magnetron 7 by the input on / off control switch to defrost.

Hereinafter, the operation of the method for decompressing a microwave oven using the thermopile sensor according to the present invention will be described with reference to FIGS.
It will be described based on. First, when a user inputs a decompression key to perform decompression, variables for executing the algorithm are initialized. That is, after substituting 0 for the variable ti (S100),
The magnetron 7 is turned off for the initial tp time, and the food and drink 1
An initial temperature of 0 is measured. Here, the tp time is a time obtained by adding one rotation time of the turntable 9 and a rotation response time until the turntable motor 8 rotates normally. If one turn time of the turntable 9 is 10 seconds,
If the rotation response time of the turntable motor 8 is 3 seconds, the tp time will be 13 seconds.

Next, while counting the elapsed time (t) of the decompression operation, it is checked whether or not the sampling time ts of the voltage signal has elapsed (S101). When the sampling time ts has elapsed, tr = After calculating t-tp (S102), the tr is compared with tc + ta (S103). As a result of the comparison, when tr is greater than tc + ta, the magnetron 7 is turned off to terminate thawing (S104), and when tr is not greater than tc + ta, the voltage data V output from the analog / digital conversion unit 4 is output. It is read and converted to the corresponding temperature T (S1
05). Here, tc indicates a time point at which the surface temperature change rate of the food starts to increase, and ta indicates a thawing time added from the time point tc.

Next, the temperature T converted in step S105 is filtered using a digital filter algorithm to calculate a temperature Tf from which noise has been removed (S1).
06), during a predetermined magnetron on / off period tm,
After calculating the maximum value Tmax, the minimum value Tmin, and the average value Tmean of the temperature Tf (S107), the tr and t are calculated.
i + tm and magnetron on / off period tm
Is determined (S108).

As a result, if tr and ti + tm are different without elapse of the magnetron on / off period tm, a control signal is output to the magnetron on / off switch to repeat steps S101 to S107 to repeat the magnetron on / off operation. If the off period tm has elapsed and tr and ti + tm are the same, the maximum value Tmax with respect to the temperature Tf of the food and drink that vibrates finely is filtered to obtain the filtered value Tmaxf (S109). Filtering at this time is as follows: Tmax (t−tm) and m
ax (t).

Tmax (t) = (Tmax (t−tm) + Tmax (t)) / 2 (10) where Tmax (t) is the maximum value T calculated at time t
max. Next, a change in the filtered maximum value Tmaxf is calculated by the following equation (S11).
0).

ΔTmaxf (t) = Tmaxf (t) −Tmaxf (t−tm) (11) where ΔTmaxf (t) is ΔT calculated at time t.
max value. Thereafter, when the change value ΔTmax of the filtered maximum value is calculated, it is determined whether or not the calculated change value is increased (S111). In this case, as shown in FIG. The increase time point of the change value ΔTmax of the filtered maximum value appears differently depending on the condition (1). In particular, in the case of FIG. 18B, it is not possible to determine whether or not an inflection point is caused by a simple increase in ΔTmax.
That is, in FIG. 18B, the point B represents the actual inflection point, but the point A is recognized as the inflection point, and there is a case where it is not decompressed. In the case of small foods, inflection points appear within a short time as shown in FIGS. 19A and 19B, so that the number of data for determining inflection points is limited.

FIG. 20 shows a method of determining an inflection point in order to solve such a problem. That is, when tr is smaller than three magnetron on / off cycles (3 × tm), ΔTmaxf (tr) of the current ΔTmaxf value
And ΔTmaxf of the ΔTmaxf value before the tm time
(Tr-tm), when ΔTmaxf (tr) is larger than ΔTmaxf (tr-tm), ΔTm
It is determined that axf has increased, and when it is small, it is determined that ΔTmaxf does not increase.

When tr is larger than 3 × tm, ΔTmaxf (t) of the current ΔTmaxf value and t
ΔTmaxf value before m time and before 2 × tm time
Tmaxf (tr−tm) and ΔTmaxf (tr−2
× tm), ΔTmaxf (tr) becomes ΔTm
ΔTmaxf (tr−2 × tm) + δ, which is larger than af (tr−tm) and larger than 0 and larger than 0.
If it is greater than, it is determined that ΔTmaxf increases.

On the other hand, if it is determined in step S111 that the filtered change ΔTmax of the maximum value increases, the additional decompression time is calculated by using equations (8) and (9), and the current time tc is added to the variable tc. Was replaced (S112)
Thereafter, the magnetron-on time ratio (P) is calculated using the above equations (1) to (9) (S113), and it is determined whether or not the thawing algorithm is abnormal and whether or not the food is in an abnormal state (S114). Here, the possibility of the abnormal state is determined by using the average value Tmean with respect to the temperature, the magnetron-on time ratio P, and the elapsed time.

In step S114, if it is determined as an abnormal phenomenon, the magnetron 7 is turned off to end the thawing. If not determined as an abnormal phenomenon, a control signal is output to the magnetron on / off switch 6 and a new magnetron on / off state is output. After initializing a variable necessary for calculating the variable value with respect to the off-period time tm, tr is replaced with ti.

According to such a process, the frozen food is thawed at an optimum time. As described above, the output of the magnetron is controlled in two stages of ON or OFF. However, if the magnetron is controlled in multiple stages, the magnetron on / off time calculation part may be changed to a part for calculating the magnetron output amount. That is, the magnetron-on time ratio P calculated by the equations (1) to (5) may be set as the magnetron output amount Pm.

As described above, the output of the magnetron is continuously controlled by using the measurement data of the thermopile sensor to thaw the food to an optimum state regardless of the size of the food and drink, thereby maximizing the thawing time. Can be. In another method for determining the ending point of the thawing, the magnetron-on time ratio P and the temperature increase rate are determined in combination as follows.

P−Kd × {T (k) −T (k−1)} ≦ Dr (12) When Expression (12) is satisfied, the decompression is completed. Here, T (k-1) is the magnetron on / off period (t
m) Temperature of food and drink measured before time, Dr is a constant value, and Kd is a value that changes according to the degree of eccentricity of load (food and drink). FIG. 21 shows a change in temperature measured by the thermopile sensor according to the eccentricity of the load. After all, when the load is eccentric, the amount of temperature change is small, so that the end point of thawing becomes longer and over-thawing occurs. Therefore, it is necessary to increase the value of Kd and terminate the thawing for a small amount of temperature change. However, in order to know the degree of eccentricity of the load, the oscillation width of the measured temperature obtained during one rotation of the turntable is required. AO is used.

FIG. 22 shows the variation of the vibration width AO of the measured temperature in accordance with the degree of eccentricity of the load when the turntable is rotated. The oscillation width AO of the obtained measurement temperature becomes large. Then, in order to calculate the Kd value according to the degree of eccentricity of the load, a relational expression between the vibration width AO and the Kd value that changes according to the eccentricity should be obtained. In the present invention, the Kd value is calculated from the vibration width using a search table. Find the value of For example, FIG.
As shown in FIG. 3, the value of Kd is set to K1 in the range where the vibration width is smaller than the constant a1, and the value of Kd is set to K2 in the range where the vibration width is larger than the constant a2. If the value is between a1 and a2, the value of Kd is k
Set to a value between 1 and K2.

Referring to FIG. 24, the method of determining the decompression end point in consideration of the degree of eccentricity of the load and the vibration width according to the above will be described with reference to FIG. 24. After the value is specified (S200), the vibration width AO of the measured temperature is calculated for one rotation time of the turntable (S201). Next, a Kd value is calculated using a search table in accordance with the oscillation width (AO) (S202), and the subtraction temperature (T (k)) of the food is measured every time the magnetron on / off cycle (tm) elapses. Then, the magnetron-on time ratio P is obtained by integrating the relative temperature value obtained by subtracting the initial temperature (T (O)) from the measured current temperature (T (k)) with the Kd value (S203). Next, the change amount (T (k) -T (k-1)) of the load temperature measured for each magnetron on / off cycle tm is integrated with the Kd value, and the magnetron on time obtained in step S203 is calculated. When the value obtained by subtracting the integrated value from the ratio P is smaller than or equal to the constant Dr, the thawing is terminated, otherwise, one magnetron on / off cycle is increased again,
The above operation is repeated.

As described above, the thawing end point is determined according to the oscillation width AO of the measured temperature measured during one rotation time of the initial turntable and the degree of eccentricity of the load, and the thawing is performed.

[0067]

As described above, in the microwave oven using the thermopile sensor and the thawing method thereof according to the present invention, the output of the magnetron is controlled continuously using the temperature measured by one thermopile sensor. ,
Performs optimal thawing regardless of the size of food and drink, shortens the thawing time, obtains the vibration width of the measured temperature during one rotation time of the initial turntable, and completes thawing considering the eccentricity of the load. Determining the time point has the effect that optimal thawing can be performed regardless of the position of the load.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a microwave oven using a thermopile sensor according to the present invention.

2 (A) and 2 (B) are explanatory diagrams showing the relationship between the size of food and drink and the field of view of a thermosensor module located on one upper side of a heating chamber in FIG.

FIG. 3 is a block diagram showing another embodiment of the microwave oven using the thermopile sensor according to the present invention.

FIGS. 4A and 4B are explanatory diagrams showing the relationship between the size of food and drink and the field of view of a thermosensor module located on one upper side of a heating chamber in FIG. 3;

5 (A) and 5 (B) are characteristic diagrams showing a change and a change rate of a surface temperature of a food and drink appearing when the frozen food is thawed in FIG.

6 (A) and 6 (B) show the change and the rate of change of the surface temperature of the food actually measured by the thermopile sensor according to the size and the position of the food when the frozen food is thawed in FIG. FIG. 9 is a characteristic diagram showing a change and a rate of change of the surface temperature of food and drink when the food and drink are located at the center of the turntable.

7 (A) and 7 (B) show changes and rates of change in the surface temperature of food actually measured by a thermopile sensor according to the size and position of food when thawing frozen food in FIG. FIG. 9 is a characteristic diagram showing a change and a rate of change of the surface temperature of the food when the food is eccentric from the center of the turntable.

FIG. 8 is a characteristic diagram of a magnetron-on time ratio P depending on a surface temperature of food and drink according to the present invention.

FIG. 9 shows the magnetron on / off period t in the present invention.
FIG. 9 is a magnetron on / off control output waveform diagram when m is constant and the magnetron on / off time changes.

FIG. 10 shows the magnetron on time to in the present invention.
FIG. 10 is a magnetron on / off control output waveform diagram when n is constant and the magnetron on / off period tm changes.

FIG. 11 is a block diagram showing the microcomputer in FIG. 1;

12A and 12B are characteristic diagrams of a temperature change and a temperature change rate with respect to a maximum value, an average value, and a minimum value with respect to temperature in the present invention.

FIGS. 13A and 13B are graphs showing examples of calculating an additional thawing time in the present invention.

FIG. 14 is an operation diagram (part 1) illustrating a method of thawing a microwave oven using the thermopile sensor according to the present invention.

FIG. 15 is an operation diagram (part 2) illustrating a method of defrosting a microwave oven using the thermopile sensor according to the present invention.

FIG. 16 is an overall timing chart at the end of decompression in FIG.

FIG. 17 is an explanatory diagram showing an example of an automatic thawing method when the magnetron on / off cycle is constant and the magnetron on time is different in FIG. 11;

18 (A) and (B) show the maximum value Tm in the present invention.
6 is a temperature change rate graph (part 1) of a change value ΔTmaxf with respect to a value Tmaxf obtained by filtering ax.

19 (A) and (B) show the maximum value Tm in the present invention.
6 is a graph (part 2) of a temperature change rate of a change value ΔTmaxf with respect to a value Tmaxf obtained by filtering ax.

FIG. 20 is a flowchart for determining whether the change value ΔTmaxf can be increased in FIG.

FIG. 21 is a graph showing the relationship between the degree of eccentricity and the change in measured temperature for the same load in the present invention.

FIG. 22 is a graph showing a relationship between a degree of eccentricity of a load and a vibration width generated when a turntable rotates in the present invention.

FIG. 23 is a graph showing a relationship between a vibration width and a Kd value in the present invention.

FIG. 24 is another embodiment of the method of thawing a microwave oven using the thermopile sensor according to the present invention.

FIG. 25 is a block diagram showing a conventional microwave oven.

FIG. 26 is a magnetron output control timing diagram for thawing the frozen food in FIG. 25;

FIG. 27 is an operation diagram of a conventional microwave oven thawing method.

28 (A), (B) and (C) are graphs of the L value at the time of thawing of the frozen food in FIG. 27, (A) is a graph of the L value appearing when the load is appropriate, and (B) Is a graph of L values that appear when the load is large, and (C) is a graph of L values that appear when the load is small.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Heating room 2 ... Thermosensor module 3 ... Amplification part 4 ... Analog / Digital conversion part 5 ... Microcomputer 6 ... Magnetron on / off switch 7 ... Magnetron 8 ... Turntable motor 9 ... Turntable 10 ... Food and drink

Claims (9)

[Claims] 1. A thermopile sensor module (2) that collects infrared rays generated from food and drink (10) and infrared rays generated from a turntable (9) to generate corresponding voltages, respectively, and the thermopile sensor module (2). An amplification unit (3) that amplifies the output voltage of the amplifier to a predetermined level and outputs the amplified voltage
An analog / digital converter (4) for converting the voltage signal of the amplifying unit (3) into a digital voltage signal and outputting the digital voltage signal; and inputting and processing the voltage signal of the analog / digital converter (4) and being built therein. The microcomputer (5) controls the magnetron on / off switch (6) by executing the algorithm for the thawing method to control the energy supplied from the magnetron (7) to the food (10) in the heating chamber (1). The microcomputer (5), wherein the microcomputer (5) reads the digital signal output from the analog / digital converter (4) at predetermined time intervals (ts).
1) converting the sampled voltage signal into a temperature T, removing noise included in the converted temperature (T), and obtaining the highest value of the temperature during the magnetron on / off period (tm) time. (Tmax), a minimum value (Tmin), and an average value (Tmean).
2) a temperature data sampling unit (53) that samples and outputs a maximum value (Tmax), a minimum value (Tmin), and an average value (Tmean) with respect to the temperature T for each magnetron on / off cycle; Using the data sampled in the section (53), the magnetron on / off is optimized for each magnetron on / off cycle.
Calculate the off-time, determine the thawing end time to end the thawing at the optimal time, judge whether the food or drink is in an abnormal state, and end the thawing in case of an abnormal phenomenon, magnetron on time ratio Calculation and abnormal phenomenon determination unit (54)
A magnetron on / off switch control unit that outputs a control signal to a magnetron on / off switch (6) based on the output of the magnetron on time ratio calculation and abnormal phenomenon determination unit (54) to control the output of the magnetron (7). (55) A microwave oven using a thermopile sensor, comprising: 2. An algorithm for converting a voltage signal sampled at predetermined time intervals (ts) into a temperature (T) and removing noise included in the temperature (T). A digital filter algorithm for calculating the maximum value of the temperature (Tmax) during the magnetron on / off period (tm), and a minimum value for the temperature between the magnetron on / off period (tm) ( Tmin) and an average calculation algorithm for determining an average value (Tmean) of the temperature during the magnetron on / off period (tm) time. A microwave oven using the described thermopile sensor. 3. The magnetron is turned off for a time obtained by adding one rotation time of the turntable and a rotation response time until the turntable motor rotates normally at the time of input of the decompression key, and the initial temperature of the food and drink is reduced. T) sensing the temperature (T) detected in the first step; filtering the temperature (Tf) using a digital filter to the temperature (Tf); A second step of calculating a maximum value (Tmax), a minimum value (Tmin), and an average value (Tmean), respectively, during the magnetron on / off cycle; and determining whether the magnetron on / off cycle has elapsed. If not, the first and second steps are repeated, and if it has elapsed, the maximum value (Tmax) is filtered to calculate a filtered value (Tmaxf). 3 stages and the highest value in the third stage filtering value (Tmax) change value (Tmaxf) a (ΔTmaxf) is calculated,
A fourth step of judging whether or not the increase has occurred, and if the change value (ΔTmaxf) has increased in the fourth step, an additional thawing time (ta) is calculated to determine a ending time of the thawing, and then the magnetron-on time ratio is determined. Calculating the magnetron-on time ratio immediately if the change value (ΔTmaxf) has not increased, and the magnetron-on time ratio calculated in the fifth step, the average value (Tmean) and the current value. A sixth step of determining whether or not the thawing algorithm performs an abnormal operation and determining an abnormal state of food and drink by using the elapsed time up to; Ending the thawing and, when it is determined that the state is not abnormal, returning to the first step and repeating the seventh step, and sequentially performing the seventh step. Decompression method. 4. The magnetron-on time ratio (P)
The method according to claim 3, wherein the calculation is performed using a minimum value (Tmin) for the temperature instead of the temperature (T) of the food and drink. 5. The thermopile sensor according to claim 3, wherein the end point of the thawing is calculated using a maximum value (Tmax) for the temperature of the food and drink instead of the temperature (T) of the food and drink. How to defrost a microwave oven. 6. The thermopile according to claim 3, wherein the abnormal state is determined using an average value (Tmean) with respect to the temperature (T), the magnetron on time (P), and an elapsed time up to the present. A method of thawing a microwave using a sensor. 7. The change value (ΔTmax) of the filtering value (Tmaxf) having the highest value (Tmax) in the fourth step.
f) is determined by the time (t)
When r) is smaller than three magnetron on / off cycles (3 × tm), ΔTmaxf of the current ΔTmaxf value
(Tr) and ΔTmax of ΔTmaxf value before tm time
f (tr−tm) and ΔTmaxf (tr)
Is larger than ΔTmaxf (tr−tm), ΔTm
4. The method for thawing a microwave oven using a thermopile sensor according to claim 3, wherein it is determined that axf has increased, and when it is small, it is determined that ΔTmaxf has not increased. 8. The change value (ΔTmax) of the filtering value (Tmaxf) having the maximum value (Tmax) in the fourth step.
f) is determined by the time (t)
When r) is smaller than three magnetron on / off cycles (3 × tm), ΔTmaxf of the current ΔTmaxf value
(Tr), Δ before time tm and before 2 × tm
ΔTmaxf (tr−tm) and ΔTm of Tmaxf values
axf (tr−2 × tm), ΔTmaxf
(Tr) is larger than ΔTmaxf (tr−tm),
When it is larger than ΔTmaxf (tr−2 × tm) + δ (positive number larger than 0 and smaller), ΔTmaxf
4. The method for thawing a microwave oven using a thermopile sensor according to claim 3, wherein it is determined that the temperature of the microwave oven increases, and it is determined that the temperature of the microwave oven does not increase. 9. A value (Kd) converted according to a first step of calculating a vibration width of a measured temperature during one rotation time of an initial turntable, and an eccentricity corresponding to the vibration width calculated in the first step. And calculating a magnetron-on time ratio (P) by multiplying a relative temperature value obtained by subtracting the initial temperature from the current temperature of the load for each magnetron on / off cycle tm by a weight different from each other. A third step, and subtracting a value obtained by multiplying the load temperature change measured at each magnetron on / off cycle (tm) by the value (Kd) from the magnetron on time (P) obtained in the third step. And a fourth step of terminating decompression when the value obtained is smaller than a specific constant value (Dr).