JPS63201429A - Electronically controlled cooker - Google Patents

Abstract

PURPOSE:To prevent overheating or waste of time, by calculating a desired time based on the heating state at the initial time of heating. CONSTITUTION:When the temperature (T) detected by a sensor 7 reaches an initial temperature Ta, a fourth counter TM4 starts counting up time. Next when the temperature detected by the sensor 7 reaches the initial temperature Tb, the counter TM4 stops counting, and a time which is obtained by multiplying the counted amount by a predetermined constant 'alpha' is set in a memory DELTATM in a computer 8. In case that the volume of a food 6 is little, the time (t) needed for the temperature detected by the sensor to reach the initial temperature Tb from Ta is short, and the time to be set in the memory DELTATM is also short. While if the volume of a food 6 is much, the time (t) which is to be set in the memory DELTATM is long as well. The sensor 7 continuously detects the temperature that is higher than a primary desired temperature T1 for the time being set in the memory DELTATM during heating by microwaves (HM), and next it detects the temperature that is higher than a secondary desired temperature T1'(=T1) after the heating by microwaves (HM) is stopped. Then the computer 8 judges that the temperature in the food has correctly reached the desired temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an electronically controlled cooking device that detects the temperature of food and controls microwave heating based on the detected temperature.

(B) Conventional technology In this type of cooking device, microwaves are supplied to the heating chamber to heat the food, while the temperature of the food is detected using a temperature sensor, such as an infrared sensor, located outside the heating chamber. Heating is terminated when the temperature reaches a desired temperature.

In this case, the structure is designed to prevent the microwaves supplied into the heating chamber from leaking to the outside as much as possible, but such leakage cannot be completely suppressed, and if such leakage occurs, When the noise multiplies the output of the infrared sensor, the signal-to-noise ratio of the sensor drops significantly, making it impossible to perform heating control at an accurate temperature and resulting in a poor quality of food.

For example, when microwave leakage occurs as described above, the temperature detected by the infrared sensor is shown in Fig.
As shown in Figure 5 of Publication No. 589), the noise rises with the passage of time while fluctuating significantly up and down, and as a result, the desired heating temperature T1 has not actually been reached and the temperature is rising. Even though the temperature is T2, the heating control is stopped at the moment A when the detected temperature instantaneously reaches the temperature T1, resulting in a poor finish of the food.

Therefore, it has been proposed to perform control as shown in FIG. 9 (which corresponds to FIG. 3 of Japanese Unexamined Patent Publication No. 143589/1989). In this case, during microwave heating, the infrared sensor maintains the first desired temperature T1 or higher for the first period t1C, for example, 5
seconds), and then the microwave heating is stopped, and during this stop, the infrared sensor reaches the second desired temperature T.
1' (this temperature is the same as the above-mentioned first desired temperature T1) or more is detected continuously for a second period t, 2 (for example, 5 seconds), the food is not affected by the leaked microwaves. It is determined that the desired state has been achieved and heating is terminated. Therefore, even though the desired heating temperature has not actually been reached and the temperature is T2, at time A when the detected temperature instantaneously reaches the desired heating temperature, the heating control is stopped as shown in Fig. 8. This prevents food from becoming poorly finished. In addition, during the above heating stop, the second desired temperature
, 4 or more cannot be detected continuously during the second period t2, the heating in the first period t1 and subsequent steps are repeated after the desired period 10.

Now, FIG. 9 above shows the temperature detected by the infrared sensor with microwave noise, but the corresponding actual food surface temperature C (without noise) changes as shown in FIG. 10.

Considering the desired temperature T1 and the part H in the figure which exceeds T1, the first period t1 is always constant regardless of the amount of food.

Therefore, if the amount of food is small now, the temperature of the food increases rapidly due to heating, and within the first period t1, the surface temperature of the food reaches the desired temperature TI, as shown by the solid line in FIG.
If T1' is too high, it will be overheated.

Furthermore, if the amount of food is large, the speed at which the food temperature rises due to heating is slow, and within the first period t1, the food surface temperature becomes slightly higher than the desired temperatures TI and Tl', as shown by the dashed-dotted line in Fig. 11. It's nothing more than that.

Then, the second period t2 for the next heating stop is delayed, and even though the surface temperature of the food actually reaches the desired temperature T1, 8T11 and the food is finished well, the first period t1 reappears. The process after heating is repeated undesirably, and time is wasted.

r-+ Problems to be Solved by the Invention The purpose of the present invention is to enable accurate temperature detection without being affected by microwaves, and to avoid overheating or wasting time. shall be.

B) Means for Solving the Problems The present invention provides a microphone that oscillates microwaves for heating food, a mouth wave oscillation means, a temperature sensor for detecting the temperature of food, and a detection device for the temperature sensor. In the electronically controlled cooking device, the controller includes a controller that controls the driving of the microwave oscillating means based on the temperature, and the controller includes a calculating device that calculates a desired time based on the heating status at the initial stage of heating, and After the temperature detected by the detector reaches the first desired temperature, a continuation means continues the heating for the desired time as long as the temperature reaches the first desired temperature; and after the continued heating, the temperature is detected while the heating is stopped. a detection means for detecting the temperature of the food by a container; and for terminating the heating when the temperature detected by the detection means is higher than the second desired temperature, and for continuing the heating when the temperature detected by the detection means is lower than the second desired temperature. means,
It is characterized by having a detection means and a determination means for repeating itself.

(E) Function: Accurate temperature detection is performed without being affected by microwaves.

Further, the desired time period for continued heating after the temperature detected by the temperature sensor reaches the first desired temperature is calculated based on the heating status at the initial stage of heating. For example, when the amount of food is small,
The food temperature rises quickly, and of course the food temperature rises quickly, which is the heating condition at the initial stage of heating, and at this time, the above-mentioned desired time is calculated to be a short time. Therefore, overheating does not occur during the desired time as in the conventional case.

Furthermore, when the amount of food is large, the temperature of the food increases slowly, and of course the temperature of the food increases slowly, which is the heating condition at the initial stage of heating, and in this case, the desired time is calculated to be a long time. Therefore, during the desired time, the food temperature rises to a certain extent and does not lead to overheating), thereby preventing the food temperature from dropping undesirably during subsequent temperature detection as in the conventional method. No time is wasted.

(f) Example The drawing shows a microwave oven according to an embodiment of the present invention.

Figure 1 shows a cross section of the microwave oven, in which microwaves oscillated from a magnetron (1) as a microwave oscillation means enter a heating chamber (4) in the main body (3) via a waveguide (2). Turntable (5) supplied with such a microwave
The food (6) above is heated. On the other hand, the heating chamber (4)
A temperature detector, ie, an infrared sensor (7), is provided outside to detect the temperature of the food by receiving infrared rays from the food 16). The microwave oscillation of the magnetone (11) is controlled based on the detected temperature signal from the sensor (7).The microwave supplied into the heating chamber (4) Although efforts are made to prevent leakage of microwaves to the outside as much as possible, such leakage of microwaves cannot be completely suppressed.

FIG. 2 shows the circuit of the microwave oven, which is equipped with a control section, that is, a microcomputer (8) that controls the microwave oven, and the computer is installed on the front operation panel (not shown) of the main body (3). Input various information such as heating temperature from the provided keyboard (9), and input temperature information detected by the infrared sensor (7) through the A/D conversion converter α valve, and based on these image information. The output of the heating signal H is controlled by When such a heating signal H is output, the switching circuit (111) consisting of a bidirectional thyristor is turned on, and power from the commercial power supply α2 is supplied to the high voltage circuit αJ, which causes the magnetron (1
High pressure is applied to 1, microwaves are oscillated, and heating is performed.

Next, the operation of the microwave oven will be explained based on the flowchart of the program of the microcomputer (8) shown in FIG.

Normally, a program cycles through the Sl and S2 steps. In the S1 step, various information entered by key operations on the keyboard (9) is input into the computer (8), and S
In step 2, it is determined whether the key operation is related to starting heating.

For example, when a desired heating temperature T1 is operated on the keyboard (9) to perform heating to a desired temperature, the information is input into the computer (8) in 81 steps, and then a key is pressed to start heating. When this operation is performed, the program exits the cycle of steps S1 and S2 and reaches step S3. In this step, the flag FL in the computer (8) is cleared. In the following steps S4 and S5, the third and fourth counters TM in the computer (8) are
3. TM4 is reset.

The program then cycles through steps 86-812. In steps S6 and S7, the first and second kakuntas TM1 and TM2 in the monitor (81) are reset.

In step S8, the heating signal H is output and microwave heating is started, and in step S9, the computer (8
) The detected food temperature in centimeters (7) is input. S1
In step 0, it is determined whether the detected temperature has not yet reached the first desired temperature T1. In steps 811 and 812, it is determined whether the detected temperatures have not yet reached the initial temperatures 'rb and 'ra. These temperatures Ta and Tb are temperatures that the detected temperature can reach at the initial stage of heating the food, and the relationship Ta<Tb holds true.

In such a cycle from 86 to 812 steps, the temperature detected by the sensor (7) gradually rises while fluctuating up and down due to the noise caused by the leaked microwave, as shown by the solid line in FIG. 4a. Incidentally, FIG. 4 shows the time course of microwave heating. Hereinafter, such FIG. 4 will also be referred to.

When the temperature detected by the sensor (7) first reaches the initial temperature Ta in the initial stage of heating, the program exits the above cycle at step 812 and reaches step 815. In this step, the fourth counter TM4 starts counting up the time. The program then returns to step S6 and cycles through steps 86-813.

Then, when the temperature detected by the sensor (7) reaches the initial temperature Tb in the initial stage of heating, the program starts from 86 to 8.
The cycle of 13 steps ends at step 811 and reaches step 814. In this step, it is determined whether the flag FL is cleared. Cleared in this case, the program then proceeds to step 815.

Step 815 corresponds to the calculation means of the present invention, and in this step, the up-counting of the fourth counter TM4 is stopped, and the time obtained by multiplying this count content by a predetermined constant α (for example, 0.2) is calculated by the computer. (8) Memory Δ'I'MK is set.

Here, if the amount of food is small, the food temperature rises quickly, and of course the food temperature rises quickly, which is the heating condition at the initial stage of heating, so the detected temperature changes from the initial temperature Ta to Tb.
The time required to reach (the contents of the fourth counter TM4) is short, and the time set in the memory ΔTM is also short. On the other hand, if the amount of food is large, the memory ΔTM
The time set to is long.

In the following step S16, the flag FL is set to 1.

The program then returns to step S6, this time 86
The process cycles through steps 811 to 811 and S14. After that, heating progresses, and when the temperature detected by the sensor (7) instantaneously reaches or exceeds the first desired temperature T1 at point A due to the influence of noise, the program exits the cycle of steps S6 to S11.814 at step 817. Reaching the steps. In this step, the first counter TM1 increments the time.

The next step 818 is interrupted by the continuation means of the present invention, and in this step it is determined whether the count content of the first counter TMI is greater than or equal to the content of the memory ΔTM.

In this case, the answer is no, so the program returns to step S8, and then goes to step S9, where the temperature is detected again.
At step 0, it is determined whether the detected temperature has reached the first desired temperature T1.

However, at this point, assuming that the detected temperature is lower than the first desired temperature T1 after the above-mentioned instantaneous state, the program proceeds from step 810 to step 811.
The process returns to step 86 via step S14, where the first counter TM1 is reset and its counting is stopped. The program then cycles through steps 86-811.814 again.

After that, the heating progresses further, and even though the detected temperature fluctuates up and down, it is always higher than the desired heating temperature T1 [after point α1]. In this case, the program cycles through steps 88 to 810 degrees, 817. When this cyclic state continues for the time set in Mesori ΔTM, the program advances to step 819. In this step, the third counter T
v'1# is added to M3, and in the next step 820 it is determined whether the content of the third counter TM3 is 14#. In this case, it is 11#, so the program is 8
Proceed to step 21. In this step, output of the heating signal H is stopped and microwave heating is stopped.

The program then cycles through steps 822 and 823. At step 822, the second counter TM2 starts counting up the time. In step S23, it is determined whether the count has reached 5 seconds or not.

After 5 seconds have elapsed, the program proceeds to step 824 (corresponding to the detection means of the present invention), which is similar to step S9, and then proceeds to step 825. This step corresponds to the determination means of the present invention, and in this step, the detected temperature of the sensor (7:) in step S24 is equal to the second desired temperature T1'.
(In this case, it is determined whether T1-'l'l) has been reached. In this case, the detected temperature is extremely accurate since microwave heating is stopped and there is no microwave noise at all, and the detected temperature is a temperature Tfl) lower than the current heating temperature T1. If so, the program returns to step S6, passes through step S7 again, and reaches step S8, where microwave heating is started.

In such a state, although the temperature detected by the sensor (7) fluctuates up and down, it immediately becomes equal to or higher than the desired heating temperature T1, so that the program continues to operate at S9, S10, and Sf7.8.
18 steps and return to S8 step), and S8 to S1
0.817.818 steps will be cycled. In such a cycle, when the time set in the memory ΔTM has elapsed, the program returns to step 819, where the content of the third counter TM3 becomes 2, and then proceeds to step S20.
After passing through steps 821, the microwave heating is stopped.

Then, in step 824, if the temperature is accurately detected without any microwave noise,
It is assumed that the detected temperature is a temperature Tn that is higher than the temperature T7A but still lower than the first desired temperature TI'. The program then returns to step S6 and then to step S7.
Through the steps 88 to 810, 817.81B steps are similarly cycled for the time set in the memory ΔTM,
Thereafter, through steps 819 and 820, the microwave heating is stopped at step 1921. If the temperature is accurately detected in the subsequent step 824, and in this case the detected temperature is assumed to be equal to or higher than the second desired temperature T1', the program then returns from step 825 to step 81, and heating ends. do.

Here, the senna (7) continuously detects the first desired temperature T1 or more during the heating of the micro-liquid for the time set in the memory ΔTMIC, and then, after stopping the microwave heating, detects the second desired temperature TI' ( mT1) or above is detected, whereby the computer (8) determines that the food temperature has correctly reached the desired temperature.

Incidentally, the heating for the time set in the memory ΔTM and the subsequent heating stop are repeated, and during this period the third counter TM3
When the content becomes 4, the program immediately returns from the s2o step to the S1 step, and heating ends at this time as well.

Now, Figure 4 above shows the temperature detected by the infrared sensor (7) with microwave noise, but the corresponding actual surface temperature of the food (without noise) changes as shown in Figure 5. do.

Thus, the desired temperature 'l'1. To explain in detail about the H part in the same figure that exceeds TI', when the amount of food is small, the memory ΔT
The time set in M is short, so even if the temperature rise speed is fast, the food temperature that rises within this time will not be higher than the desired temperature T1 and T1 as shown in Figure 6. ((Point P), there will be no overheating. In this case, the food temperature at Point P will be the desired temperature TI when the food temperature is detected after 5 seconds have passed after stopping heating. , TI' is not slightly higher than the desired temperature 'l'fL'l'?'.

Also, if the amount of food is large, the time set in the memory ΔTM will be long, so even if the temperature rise speed is slow, the food temperature that rises within such a time will be the desired temperature TI, TI' as shown in Figure 7. The cQ point is reasonably high: at this point, it is not overheating). As a result, when the food temperature is detected after 5 seconds have passed after the heating is stopped, the temperature of the food will not be lower than the desired temperature T1, T1'', and the undesired food temperature will not be lower than the desired temperature T1, T1'' again after heating for the time set in the memory ΔTM. Don't waste time repeating things over and over again.

In this example, the heating status at the initial stage of heating is determined based on the time required from the initial temperature Ta to Tbj.
<tb) and may be determined based on the range of temperature rise from ta to tb.

(G) Effects of the Invention According to the present invention, accurate temperature detection can be performed without being affected by microwaves, and in addition, it is possible to suppress excessive heating and waste of time as in the conventional methods, and it is possible to do so in a practical manner. We can provide standard cooking utensils.

[Brief explanation of the drawing]

1 to 7 relate to the microwave oven of the embodiment of the present invention,
Figure 1 is a sectional view, Figure 2 is a circuit diagram, Figure 5 is a program flowchart, Figures 4 and 5 are heating characteristic diagrams, Figures 6 and 7 are enlargements of part 8 of Figure 5. Characteristic diagrams, Figure 8 is a heating characteristic diagram of a conventional microwave oven, Figures 9 and 10 are heating characteristic diagrams of other conventional microwave ovens, and Figure 11 is an enlarged characteristic of part 8 of Figure 10. It is a diagram. (11... magnetron, (7)... infrared sensor, (81... microcomputer).

Claims (1)

[Claims] (1) Microwave oscillation means for oscillating microwaves to heat food, a temperature sensor for detecting the temperature of the food, and controlling the driving of the microwave oscillation means based on the temperature detected by the temperature sensor. In the electronically controlled cooking appliance, the control unit includes a calculation unit that calculates a desired time based on the heating status at the initial stage of heating, and a calculation unit that calculates a desired time based on the heating status at the initial stage of heating, and , a continuation means for continuing the heating for the desired time as long as such a temperature is reached; a detection means for causing the temperature sensor to detect the temperature of the food with the heating stopped after such continued heating; a determining means for causing the heating to end when the temperature detected by the means is higher than a second desired temperature, and for causing the heating to be repeated when the temperature detected by the detecting means is lower than the second desired temperature; An electronically controlled cooking device comprising: