JPH026417B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention detects food temperature with an infrared sensor,
The present invention relates to a cooker that attempts to control food heating based on such temperature.

(b) Prior art In recent cookers, such as microwave ovens,
An opening is formed in the wall of the heating chamber where food is stored.
In addition, an infrared sensor is disposed outside the heating chamber at a position facing the opening, and the infrared sensor receives infrared rays from the food in the heating chamber through the opening, and determines the temperature for controlling the microwave heating by the magnetron. It is designed to output a signal.

However, with such a configuration, an atmosphere containing food particles, water vapor, etc. generated from food during microwave heating passes through the opening and rises, and therefore the infrared sensor becomes contaminated by the atmosphere, causing the sensor to become dirty. The detection accuracy of infrared rays becomes poor. Therefore, most recent microwave ovens are configured to blow air into the heating chamber through the opening to prevent the atmosphere from rising during microwave heating.

However, such microwave ovens do not have any measures against stains after microwave heating is completed. That is, the air blowing through the opening is stopped immediately upon completion of microwave heating, and in this case, even after the heating is completed, food scraps, water vapor, etc., as described above, are generated from the food for a while and remain trapped in the heating chamber. ,
This is because the atmosphere containing water vapor similarly passes through the opening.

(c) Purpose of the Invention The purpose of the present invention is to prevent an infrared sensor from being contaminated by an atmosphere containing food particles, water vapor, etc. even after heating is completed.

(d) Structure of the Invention In order to achieve the above object, the present invention provides a heating chamber for storing food, a heating means for heating the food, a first blowing means for ventilating the inside of the heating chamber, and a wall surface of the heating chamber. an infrared sensor that receives infrared rays from the heating chamber through the opening and outputs a temperature signal for controlling heating by the heating means; and a second infrared sensor for blowing air into the heating chamber through the opening. The second air blowing means continues blowing air from the time of heating until at least the infrared sensor outputs a predetermined temperature signal after the end of the heating, and the first air blowing means continues blowing air at the temperature signal output from the infrared sensor. It is configured to be carried out for a predetermined period of time based on a predetermined temperature signal.

(e) Embodiment A microwave oven according to an embodiment of the present invention will be described below based on the drawings.

In FIGS. 1 and 2, 1 is an exterior, 2 is a heating chamber arranged inside the exterior and stores food 3, 4 is a door that opens and closes the front opening of the heating chamber, and 5 is a heating time, heating temperature, etc. 6 is a magnetron that supplies microwaves to the heating chamber 2 through a waveguide 7;
is a first blower device consisting of first ducts 9, 9 and a first blower 10, and after cooling the magnetron 6, the air from this device is sent to the air intake hole in the side wall 2a of the heating chamber in order to ventilate the inside of the heating chamber 2. 11, 11... to heating chamber 2
The exhaust hole 12 of the rear wall 2b of the heating chamber, together with the atmosphere containing food particles, water vapor, etc. inside the heating chamber 2,
12,... are exhausted to the outside.

13 is an infrared detection mechanism. In this mechanism, 14 is an opening formed in the center of the upper wall 2c of the heating chamber, and a microwave blocking ring 15 is fitted into the opening to block the passage of microwaves that allow infrared rays to pass. 16 is the storage box, 17 is the motor 1
8, the aperture 14, i.e. the ring 15
The chopper 19 that periodically turns on and off the infrared rays from inside the heating chamber 2 that has passed through the chopper is a pyroelectric infrared sensor that receives the infrared rays that have been cut off and on at the chopper and outputs a temperature signal based on the received infrared rays. For example, when the infrared sensor intermittently receives infrared rays from the food 3 in the heating chamber 2, it outputs a temperature signal based on the temperature of the food 3. 20 is a room temperature measurement diode for measuring the room temperature; 21 is a second blower device consisting of a second duct 22 and a second blower 23; the air from this device is sent into the storage body 13 and the sensor 19; After cooling, the opening 14, i.e. the ring 1
5 into the heating chamber 2. After that, the air is exhausted to the outside from the exhaust holes 12, 12, . . . .

FIG. 3 shows the circuit of the microwave oven, where 24 is a microcomputer (hereinafter referred to as microcomputer) that controls the microwave oven, and 25 is the operation panel 5.
The first data lines 26 and 27 input signals from the infrared sensor 19 and the room temperature measuring diode 20 into digital signals, respectively, and the second and third data lines 2
8 and 29, the first and second A/D converters provide input to the microcomputer 24; 30 is a commercial power supply;
1 is a high voltage transformer 32 and a half-wave voltage doubler rectifier circuit 3
3 is a high voltage circuit for supplying high voltage to the magnetron 6; 34 is a first switching circuit that is turned on by the heating signal M from the microcomputer 24; when this circuit is turned on, power is supplied to the high voltage circuit 31; Then, high pressure is supplied from the circuit to the magnetron 6 to perform microwave heating. 35 is the first air blow signal from the microcomputer 24
When the second switching circuit is turned on by _W1 , the first motor 10a of the first blower 10 is energized, and the first blower device 8 generates wind. Reference numeral 36 denotes a third switching circuit that is turned on by the second blowing signal W ₂ from the microcomputer 24. When this circuit is turned on, the second motor 23a of the second blower 23 is energized, and the second blower 23 is turned on.
Wind is generated from A fourth switching circuit 37 is turned on by the intermittent signal CP from the microcomputer 24. When this circuit is turned on, the motor 18 is energized and the infrared rays are intermittent.

Next, the operation of the microwave oven is controlled by the microcomputer 24.
This will be explained based on the flowchart of FIG. 4 showing the flow of the operation program.

When the power is turned on, the program enters a state (hereinafter referred to as a standby state) in which it cycles through steps S2 and S3 via the S1 step. In the S1 step, all temporary storage registers, counters, etc. in the microcomputer 24 are cleared. In step S2, heating time, heating temperature, etc. are set in a predetermined area within the microcomputer 24 by operations on the operation panel 5. In step S3, it is determined whether or not heating start operation has been performed on the operation panel 5.

When cooking, the food 3 is first placed within the detection range of the sensor 19 in the heating chamber 2, and for example, when temperature cooking is to be performed, a desired heating temperature is set using the operation panel 5. Then, in step S2, the desired heating temperature is set in a predetermined area of the microcomputer 24. Then, when you operate the heating start operation on the operation panel 5, the program exits the above-mentioned standby state.
Proceed to step S4. In this step, it is determined whether the cooking to be started is time cooking or temperature cooking. In this case, the heating temperature has been set, and temperature cooking is therefore determined, and the program then proceeds to step S5. In this step, the output of the intermittent signal CP is started and infrared rays are intermittent. The program then proceeds to step S6. In addition, in the case of time cooking, proceed directly from step S4 to step S6.

In step S6, the output of the heating signal M is started to perform microwave heating, and the output of the first ventilation signal _W1 is started to cool down the magnetron 6 and ventilate the inside of the heating chamber 2. The second air blow signal W ₂ starts outputting and the sensor 1
9 is cooled and passes through the ring 15 into the heating chamber 2.
Air is blown inward. As a result, the food 3 to be heated
The atmosphere containing food waste and water vapor generated from the ring 15 does not rise toward the sensor 19 through the ring 15. In the following S7 step, sensor 19
The temperature of the food is detected, and it is determined whether the detected temperature has reached the desired heating temperature. The program remains at step S7 until such a point is reached, after which it reaches step S8. In the case of timed cooking, in step S7 above, it is determined whether or not the desired heating time has elapsed after the start of heating, and the program remains in step S7 until such time has elapsed, and then proceeds to step S8. reach.

In step S8, the output of the heating signal M is stopped to complete microwave heating, that is, temperature cooking (or time cooking), and the output of the intermittent signal CP is stopped to stop intermittent infrared rays, and the first air blower is stopped. Signal W ₁ is stopped and magnetron 6 is cooled.
Ventilation in the heating chamber 2 stops. By stopping the ventilation, the food 3 will not be cooled down rapidly even if the food 3 is left in the heating chamber 2 after heating. At this time, the air blowing into the heating chamber 2 through the ring 15 is not stopped. As a result, food particles and water vapor are still generated from the food for a while after the heating is finished, but the atmosphere containing these remains in the heating chamber 2 due to the ventilation stop and passes through the cage ring 15 to the sensor 1.
9 is prevented from rising. The amount of air blown from the ring 15 is such that the food 3 is not cooled much faster than the food 3 naturally cools down after heating.

The subsequent operation is when the food 3 is taken out from the heating chamber 2 before it has naturally cooled to near room temperature, or when the food 3 is still left in the heating chamber 2 even after it has naturally cooled to near room temperature. belongs to.

Then, in the following step S9, the 1-second counter SEC in the microcomputer 24 is cleared, the counter SEC starts counting up, and the output of the intermittent signal CP is started to perform infrared intermittent operation. . Then, the program stays at step S10 until the 1 second counter SEC counts 1 second, and when it counts 1 second, it advances to steps S11 and S12.
The counting operation in the SEC is stopped, and the temperature detected by the sensor 19 is written into the first temperature register _T1 in the microcomputer 24 in step S12.

The next step, S13, is to determine whether the food 3 has been taken out from the heating chamber 2, as will be explained later.In this step, the temperature is written to the second temperature register _T0 in the microcomputer 24. The temperature written in the first temperature register _T1 is subtracted from the temperature being stored, and the difference is △T (for example, 5 to 10 degrees Celsius).
It is determined whether or not the above is satisfied. In this case, the first
The contents of the temperature register T ₁ are the food temperature immediately after the end of heating, and the contents of the second temperature register T ₀ are the same as the contents of the first temperature register T ₁ only immediately after the end of heating in step S8, so the above difference is △T
is smaller and the program continues to step S14.

As will be understood from the explanation below, this step S14 is for determining whether the food 3 has been naturally cooled down to near room temperature in the heating chamber 2 _. is measured, and the contents of the first temperature register _T1 are the room temperature T _D
and a constant temperature α (α≧△T, α is, for example, 5 to 10℃)
It is determined whether or not it is less than or equal to the sum of At this time as well, the content of the first temperature register _T1 is the temperature of the food immediately after heating is completed, and is therefore considerably higher than the above-mentioned added value, and the program proceeds to step S15. In this step, the contents of the first temperature register T ₁ are transferred to the second temperature register T ₀ .

The program then returns to step S9 and returns to step S10.
Step 1 is reached, and when one second has elapsed, step S11 and step S12 are reached, and step S13 is reached. In this case, the second
The content of temperature register T ₀ is the previous detected temperature,
If the above difference is still smaller than △T, the program will
Proceed to step S14. and the first temperature register
Assuming that the content of T ₁ is still higher than the above added value,
The program passes through step S15 and returns to step S9 again. In this way, as long as the difference is less than ΔT and the content of the first temperature register _T1 is higher than the added value, the program cycles through steps S9 to S15.

In such circulation, if the food 3 is taken out from the heating chamber 2 before it has naturally cooled down to near room temperature, in the subsequent step S12, the sensor 19 detects a temperature approximately equal to the room temperature T _D of the bottom wall 2d of the heating chamber. is sensed and this temperature is written into the first temperature register _T1 . On the other hand, the contents of the second temperature register _T0 in the next step S13 are the previous temperature detected by the sensor 19,
That is, as can be seen in step S14, the temperature is higher than the above-mentioned added value and has not fallen close to room temperature. In this case, in step S13, the difference is greater than or equal to ΔT, and the program then proceeds to step S16. Here, a first predetermined temperature signal TP is output from the sensor 19 in accordance with the temperature of the bottom wall 2d of the heating chamber.
Set to 1.

Thus, the sensor 19 receives the first predetermined temperature signal TP1.
In the subsequent step S16, a predetermined time t (for example, 2 to 3 minutes) is set in the ventilation counter VENT in the microcomputer 24, and down-counting of the time t is started, and the intermittent signal CP is output. It is stopped and infrared intermittent stops. In the following step S17, the output of the first ventilation signal _W1 is started again, and the heating chamber 2 is ventilated. Thereafter, the program remains at step S18 until the contents of the ventilation counter VENT reach 0, at which point it proceeds to step S19. In this step, the first and second air blowing signals are
The output of W ₁ and W ₂ is stopped, and ventilation in the heating chamber 2 and blowing of air into the heating chamber 2 through the ring 15 are stopped.

Through the above-mentioned ventilation, the atmosphere containing food waste and water vapor trapped in the heating chamber 2 is exhausted to the outside at once, so that the sensor 19 is not contaminated even when the air blowing from the ring 15 is stopped.

The program then returns to step S1 and enters a standby state.

Furthermore, in the cycle of steps S9 to S15 above,
When the food is naturally cooled to near room temperature in the heating chamber 2, the program moves from step S14 to step S16. Here, the output of the sensor 19 corresponding to the temperature in the first temperature register _T1 in step S14 in this case is set as the second predetermined temperature signal TP2.

Thus, the sensor 19 receives the second predetermined temperature signal TP2.
The program then prints as above
From step S14 to step S16 and then
Proceed to steps S17 to S19. This provides the same ventilation as described above. In this case, since the food 3 has been cooled to near room temperature, the food 3 is not further cooled by the ventilation air. In this state, almost no food particles or water vapor are generated from the food 3, and therefore, after ventilation, the sensor 19 will not become contaminated even when the air blowing from the ring 15 is stopped, as described above.

(F) Effects of the Invention As is clear from the above description, according to the present invention, there is provided a heating chamber for storing food, a heating means for heating the food, and a first heating chamber for ventilation in the heating chamber.
a ventilation means, an opening formed in the wall of the heating chamber;
an infrared sensor for receiving infrared rays from the heating chamber through the opening and outputting a temperature signal for controlling heating by the heating means; a second blowing means for blowing air into the heating chamber through the opening; The air blowing by the second air blowing means is continued from the time of heating until at least the infrared sensor outputs a predetermined temperature signal after the heating is finished, and the air blowing by the first air blowing means is continued based on the predetermined temperature signal output from the infrared sensor. Since the process is carried out for a specified period of time, the infrared sensor will not get dirty even after heating is finished, and even if the food is left in the heating chamber continuously after heating is finished, the food will hardly be cooled any faster than it would naturally cool. , can provide an extremely practical cooker.

[Brief explanation of drawings]

The drawing shows a microwave oven according to an embodiment of the present invention.
2 is a sectional view, FIG. 3 is a circuit diagram, and FIGS. 4A and 4B are flowcharts showing the flow of the operating program of the microcomputer. 2... Heating chamber, 6... Magnetron, 8... First blower, 14... Opening, 19... Pyroelectric infrared sensor, 21... Second blower.

Claims (1)

[Claims] 1. A heating chamber for storing food, a heating means for heating the food, and a first heating chamber for ventilating the heating chamber.
a ventilation means, an opening formed in the wall of the heating chamber;
an infrared sensor for receiving infrared rays from the heating chamber through the opening and outputting a temperature signal for controlling heating by the heating means; a second blowing means for blowing air into the heating chamber through the opening; The air blowing by the second air blowing means is continued from the time of heating until at least the infrared sensor outputs a predetermined temperature signal after the heating is finished, and the air blowing by the first air blowing means is continued based on the predetermined temperature signal output from the infrared sensor. A cooking device characterized in that cooking is performed for a predetermined period of time.