JPH0124354B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an electronically controlled cooking device such as a microwave oven.

(b) Prior art In recent years, as seen in Japanese Utility Model Application Publication No. 57-167303, an infrared sensor is provided to detect the temperature of the food by receiving infrared rays from the food, and microwave radiation is detected based on the temperature detected by the sensor. Microwave ovens that control heating have been commercialized. In this case, the reliability of the sensor decreases when the temperature increases. Therefore, in the above-mentioned microwave oven, it is further necessary to prevent the conducted heat from reducing the reliability of the sensor, not only during microwave heating, but also after heating is completed, while the high-temperature hot air remains in the heating chamber.
The sensor is cooled down.

However, the cooling time for the sensor after the above-mentioned heating is completed is generally set to be short, so the cooling of the sensor stops before the hot air in the heating chamber is sufficiently reduced, and the reliability of the sensor decreases. have not yet been able to prevent it. On the other hand, if the above-mentioned cooling time is lengthened, it is certainly possible to significantly prevent a decrease in the reliability of the sensor, but this may be wasted if the sensor is always cooled for a long time after heating is finished. That is, for example, when the door is opened and the food is taken out immediately after heating is finished, the high temperature air inside the heating chamber quickly escapes to the outside, and in this case there is no need for long-term cooling as described above.

(c) Object of the invention An object of the invention is to efficiently cool an infrared sensor after heating is completed without waste.

(d) Structure of the Invention In order to achieve the above object, the present invention includes a heating chamber for storing food, a door for opening and closing the opening of the heating chamber, and a door detection means for detecting the open state of the door.
a heating means for heating the food; an infrared sensor for detecting the temperature of the food by receiving infrared rays from the food; a cooling means for cooling the sensor; and the heating based on the temperature detected by the sensor. a control section for controlling the drive of the means, the control section drives the cooling means when heating the food, and after heating the food, the control section drives the cooling means for a first predetermined period of time unless the door detection means detects that the door is open. the cooling means is further driven for a second predetermined time period shorter than the first predetermined time period from the time of such detection when the door detection means detects that the door is open. shall be.

(e) Embodiments A microwave oven according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the external appearance of the microwave oven. A heating chamber 2 for storing food is arranged inside the microwave oven main body 1, and the front opening of the heating chamber is opened and closed by a door 3. FIG. When the door is closed, the latch pawl 4 is attached to the main body 1.
The closed state is maintained by engaging with a stopper (not shown) inside, and the door 3 is opened by driving the door handle 5 to release the engagement between the latch pawl 4 and the stopper. The open/closed state of the door 3 is detected by a door switch 6 in the main body 1 which is turned off and on accordingly. The door switch is operated by the latch pawl 4. Furthermore, the main body 1 has a panel section 7 on the front surface, and the panel section is provided with a keyboard 8 for setting cooking conditions such as heating temperature and heating time.

FIG. 2 shows the main parts of the microwave oven. Microwaves are supplied into the heating chamber 2 from a magnetron 9 as a heating means through a waveguide 10 to perform heating. Then, the upper wall 2 of the heating chamber 2
A microwave blocking ring 11 is attached to a. Furthermore, a metal outer box 12 is fixed on the upper wall 2a outside the heating chamber 2, and a metal inner box 13 is fixed inside the outer box.
3, an infrared sensor 14 and a temperature circuit board 15 for processing the output of the sensor are disposed as seen in Japanese Patent Application No. 58-237584. A small hole 1 in the lower wall of the inner box 13 faces the sensor 14.
6 is formed. The sensor 14 receives infrared rays from the food that is guided through the ring 11 and the small hole 16, thereby detecting the temperature of the food.

Furthermore, cooling air generated from a cooling blower 17 is guided into the outer box 12 via a ventilation duct 18. When such cooling air is guided into the outer box 12, it passes around the inner box 13, thereby substantially reducing the inner box 13.
The sensor 14 and temperature circuit board 15 inside are cooled. Thereafter, the cooling air is exhausted to the outside from the lower opening 19 of the outer box 12 and the ring 11
It is sent into the heating chamber 2 through. In this case, water vapor generated from the food during microwave heating and suspended matter such as food waste are prevented from rising through the ring 11, thereby preventing the sensor 14 etc. from becoming contaminated by such floating matter. be done.

Next, FIG. 3 shows the circuit of the above microwave oven,
A microprocessor 20 is provided as a control section. The processor inputs cooking conditions and the like from the keyboard 8, and also inputs the temperature detected by the sensor 14 via the A/D converter 21, and further inputs door opening/closing information from the door detection circuit 22 including the door switch 6. Then, based on these pieces of information, the first and second switching circuits 2
Turn 3 and 24 on and off. When the first switching circuit 23 is turned on, power from the commercial power supply 25 is supplied to a high voltage circuit 26 comprising a high voltage transformer, etc., and high voltage is applied to the magnetron 9 to perform microwave heating. Further, when the second switching circuit 24 is turned on, the blower 17 is supplied with power and driven.

Next, the operation of the microwave oven will be explained based on the flowchart of the program of the processor 20 shown in FIG.

Normally, a program cycles through S1 and S2 steps. In the S1 step, key operations on the keyboard 8 are detected, and in the S2 step, the key operations on the keyboard 8 are detected.
It is determined whether or not a cooking start operation has been performed.

For example, when performing cooking using microwave heating to a desired heating temperature, the desired heating temperature is set using the keyboard 8 and a cooking start operation is performed. Then, the program breaks out of the above cycle and
The process reaches step S3 and the above cooking is executed. That is, while monitoring the temperature detected by the sensor 14, the first switching circuit 23 is turned on and microwave heating is started. In addition, the second switching circuit 24 is turned on, the blower 17 is driven, the sensor 14 is cooled, floating objects in the heating chamber 2 are prevented from rising, and the sensor 14 etc. are prevented from becoming dirty. becomes. Then, when the detected temperature reaches the desired heating temperature, microwave heating is stopped and cooking ends. However, in this case,
The blower 17 continues to be driven.

Then, when the cooking is finished, the program switches to S4.
Proceed to step. In this step, the processor 2
The door flag DR in 0 is cleared, and the first timer TM1 and second timer TM1 in the processor 20 are cleared.
One hour as the first predetermined time and three minutes as the second predetermined time are respectively set in TM2.

In the following step S5, the open/closed state of the door 3 is detected by the door detection circuit 22, and in the next step S6, it is determined whether the door 3 is opened or not. In this case, door 3 is not open, and the program then reaches step S7. In this step, the second counter SEC in the processor 20 starts counting time. In the following step S8, it is determined whether the second counter SEC has counted one second. In this case,
There is no 1 second timing, so the program is
The process returns to step S5 and then cycles through steps S5 to S8.

When one second is counted, the program exits this cycle and reaches step S9. In this step, the time counting operation of the second counter SEC is stopped,
Its contents are cleared. In the next step S10, the first timer TM1 is decremented by one second. In the following step S11, it is determined whether the content of the first timer TM1 has become zero. Since it is not 0 in this case, the program then proceeds to step S12. In this step, it is determined whether the door flag DR is 1 or not. In this case, it is not 1, so
The program then returns to step S5. and,
Steps S5 to S8 start to cycle, and when the second counter SEC counts 1 second again,
The program goes through steps S9 to S12 again, and the first timer TM1 is further decremented by one second.

In this way, the program cycles through steps S5 to S8, but passes through steps S9 to S12 every second (hereinafter, such a state will be referred to as A cycle).

Thereafter, when one hour has passed since the end of cooking and the content of the first timer TM1 becomes 0, the program exits the A cycle and reaches step S13. In this step, the second step circuit 24 is turned off, and the driving of the blower 17, which has been continued since the start of cooking, is stopped.

Here, 1 hour after the end of cooking,
Even though there is food in the heating chamber 2, high-temperature hot air is no longer trapped, and even when the blower 17 is stopped and the cooling of the sensor 14 is stopped, the reliability of the sensor 14 will not deteriorate due to heat.

The program then proceeds to step S14. In this step, all clearable areas within the processor 20 are cleared. And the program is
The process cycles through steps S1 and S2, and becomes ready to detect key operations for the next cooking.

Next, when the program is in the A circulation state after the above-mentioned cooking is completed, when the door 3 is opened to take out the food, the program goes from the A circulation state to step S15. In this step, 1 is written to the door flag DR. After that, the program passes through steps S7 and S8 until the second counter SEC counts 1 second.
Steps S5, S6, S15, S7, and S8 are cycled, and when one second is counted, steps S9 to S12 are reached, and in this case, step S16 is reached. In this step, the second timer TM2 is decremented by one second. Continue
In step S17, it is determined whether the contents of the second timer TM2 have become zero. In this case, it is not 0, so the program returns to step S5. Thus, the program cycles through steps S5, S6, S15, S7, and S8, and steps S9 to S12, S16, and S16 every second.
The process will go through step S17 (this state will be temporarily referred to as B circulation).

Thereafter, when three minutes have elapsed since the door 3 was opened and the food was taken out, and the contents of the second timer TM2 become 0, the program exits the B circulation and proceeds to step S13, where the cooling of the sensor 14 is stopped.

At this point, since the food has been taken out and is not present in the heating chamber 2, high-temperature hot air no longer stays in the heating chamber 2 for about 3 minutes after the door 3 is opened.
Even when the cooling of the sensor 14 is stopped, the reliability of the sensor 14 does not deteriorate due to heat.

(F) Effects of the Invention According to the present invention, after heating is completed, the infrared sensor is cooled by the cooling means for a long time unless the food is taken out, and when the door is opened and the food is taken out, the infrared sensor is cooled for a long time from the time the door is opened. The sensor is cooled for the required amount of time, which is sufficient to prevent the sensor from becoming unreliable due to the heat in the heating chamber, and the cooling of the sensor is not carried out unnecessarily long; It can be done efficiently and without waste.

[Brief explanation of drawings]

The drawing shows a microwave oven according to an embodiment of the present invention.
2 is a sectional view of a main part, FIG. 3 is a block circuit diagram, and FIG. 4 is a flowchart of a microprocessor program. 2... Heating chamber, 3... Door, 6... Door switch, 9... Magnetron, 14... Infrared sensor, 17... Cooling blower, 20... Microprocessor.

Claims (1)

[Claims] 1. A heating chamber for storing food, a door for opening and closing the opening of the heating chamber, a door detection means for detecting the open state of the door, and a heating means for heating the food.
An infrared sensor for detecting food temperature by receiving infrared rays from food, a cooling means for cooling the sensor, and a control section for controlling driving of the heating means based on the temperature detected by the sensor. The control section drives the cooling means when heating the food, and after the heating of the food is finished, drives the cooling means for a first predetermined period unless the door detection means detects that the door is open. An electronically controlled cooking appliance characterized in that, when the detection means detects the door open state, the cooling means is driven for a second predetermined time period shorter than the first predetermined time period from the time of such detection.