JPS628691B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a cooking appliance that controls heating based on the temperature of food detected by an infrared detector.

(b) Prior art Conventional cooking devices of this type, such as microwave ovens,
The infrared detector is placed outside the heating chamber, and is configured to receive infrared rays from the food through an opening formed in the wall of the heating chamber and heat the food while detecting the temperature of the food. The above-mentioned opening is closed by a shutter as an opening/closing means except during heating to such a temperature, so that water vapor, oil, etc. generated from the food in the heating chamber during heating pass through the opening at least after heating is completed. This will not contaminate the infrared detector.

(c) Object of the Invention The present invention is intended to further prevent the infrared detector from being contaminated by blocking the opening as much as possible even during heating due to temperature detection.

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

1 and 2, 1 is an exterior, 2 is a heating chamber, 3 is a magnetron that oscillates microwaves for heating food 4, 5 is an opening formed in the upper wall of the heating chamber 2, and 6 7 is a microwave blocking ring attached to the opening and allows infrared rays to pass through but blocks microwaves from passing; 7 is a microwave shielding ring for receiving infrared rays from the food 4 through the opening 5 and ring 6 to detect the temperature of the food; 8 is an infrared detector; 8 is a shutter serving as an opening/closing means for opening and closing the upper end opening of the ring 6, that is, the opening 5; and 9 is a drive unit for driving the shutter. In the drive section,
10 is a support shaft that rotatably supports the shutter 8; 11 is a spring that biases the shutter 8 to rotate in the counterclockwise direction (FIG. 2) so that the shutter 8 closes the opening 5; and 12 is a spring In order for the shutter 8 to open the opening 5, the shutter 8 is moved clockwise (second direction) against the biasing force of the spring 11.
Solenoids 13 and 14 that bias the rotation of the shutter 8 in FIG. 1 are stoppers that restrict rotation of the shutter 8. 15
is a storage chamber in which the ring 6, the infrared detector 7, the shutter 8, and the drive section 9 are housed.

FIG. 3 shows the circuit of the microwave oven, where 16 is a microcomputer (hereinafter referred to as microcomputer) that controls the microwave oven, 17 is a setting unit for setting heating time, heating temperature, etc., and 18 is the infrared detection unit. A-D (analog-digital) converter that converts the detection signal from the device 7 into a digital signal, 19
2 is a commercial power supply, 20 is a high voltage supply circuit that supplies high voltage to the magnetron 3, and 21 is the microcomputer 16.
A first switching circuit 22 inputs power from the power source 19 to the high voltage supply circuit 20 in response to a heating signal H from the microcomputer 16; This is a second switching circuit for inputting the signal.

The operation of the microwave oven will now be explained.

First, when a desired heating time is set in the setting section 17 and a heating start operation is performed, the microcomputer 16
outputs the heating signal H during the heating time, thereby performing microwave heating for the desired heating time. In this case, the opening 5 is closed by the shutter 8.

Next, when performing microwave temperature heating, in this case, reference is made to the flowchart of the program of the microcomputer 16 shown in FIG. 4 and the heating temperature characteristic chart of the food 4 shown in FIG. 5.

When the desired heating end temperature T _E is set in the setting section 17 and a heating start operation is performed, the program starts at S ₁
Reaching the steps. In this step, the shutter signal S
starts outputting, the solenoid 12 is driven, and the shutter 8 rotates clockwise (Fig. 2).
The opening 5 is opened. In the next _S2 step,
The infrared rays from the food 4 are received by the infrared detector 7 through the open aperture 5, whereby the current food temperature T _F (equal to the temperature T _O in FIG. 5) is detected. In the following step _S3 , it is determined whether the food temperature T _F is lower than the heating end temperature T _E. In this case, heating has not started yet, so the food temperature T _F is the heating end temperature T _E
lower, so the program then proceeds to step _S4 . In this step, a heating signal H is output and microwave temperature heating is started. In the next step _S5 , it is determined whether the value obtained by subtracting the food temperature T _F from the heating end temperature T _E is greater than a predetermined constant temperature difference ΔT _M. This constant temperature difference ΔT _M is the maximum value at which the temperature of the food can be increased regardless of the type of food 4 during a certain time Δt _M that is measured thereafter. Now, the value subtracted above is the constant temperature difference △
If it is greater than T _M , then a certain period of time △t _M
During this period, the opening 5 is closed.

That is, the program then proceeds to steps S ₆ and S ₇ . At step _S6 , time measurement is started by the counter Δt in the microcomputer 16, and at step _S7 , the output of the shutter signal S is stopped, and the shutter 8 is rotated counterclockwise (Fig. 2) by the force of the spring 11. The opening 5 is closed. In the following _S8 step, the time measurement content of the counter △t is the above fixed time △t _M
It is determined whether or not it has been reached. In this case, such an arrival has not been made since it has just started timing.
The program therefore remains at step _S8 . Then, when the time measured by the counter △t reaches the specified time △t _M , the program starts from step _S8 .
Reach S ₉ steps. In this step, the counter △
The time measurement of t is stopped and its contents are cleared.

After that, the program returns to step _S1 again,
Therefore, the opening 5 is opened, and in the subsequent _S2 step, the current food temperature T _F (equal to the temperature _T1 in Figure 5) is detected, and in the next _S3 step, the food temperature T _F is reached at the end of heating. It is determined whether the temperature is lower than the temperature _TE . If it is also low in this case, the program similarly passes through the _S4 step and reaches the _S5 step. At this time, if the value obtained by subtracting the food temperature T _F from the end temperature T _E is still greater than the above-mentioned constant temperature difference △T _M , the program again passes through steps S ₆ to _{S 9} and continues for a certain period of time △t. During _M , the opening 5 is closed.

Thereafter, food temperature T detected sequentially in the same manner.
As long as the value obtained by subtracting _F (equal to the temperatures T ₂ , T ₃ . . . in Figure 5) from the heating end temperature T _E is greater than the constant temperature difference ΔT _M , the program cycles through steps S ₁ to S ₉ . do. Then, the opening 5 is closed for a certain period of time Δt _M after the food temperature T _F is detected.

Then, when the next detected food temperature T _F (equal to the temperature T _N in FIG. 5) is subtracted from the heating end temperature T _E , the value becomes equal to or less than a certain temperature difference ΔT _M. In this case, if the food temperature increases to produce a constant temperature difference ΔT _M during the next fixed time Δt _M , the food temperature will reach the heating end temperature _TE . Then, the program exits the cycle of steps _S1 to _S9 at step _V5 , and begins to cycle through steps _S2 to _S5 . In this case, the opening 5 is in an open state.

Then, when the food temperature T _F reaches the heating end temperature T _E , the program cycles from S ₂ to _{S 5} steps to S ₃
It exits at step S ₁₀ and steps S ₁₁ are reached.
S ₁₀ step is similar to S ₇ step, opening 5
is closed, and in step _S11 , the output of the heating signal H is stopped, thus ending the microwave temperature heating. The program then enters a standby state, and a signal from the setting section 7 for the next heating can be input.

Therefore, even during microwave heating, the time during which the opening 5 is open is extremely short, and water vapor, oil, etc. hardly ever reach the infrared detector 7.

Here, in the program of the microcomputer 16, steps S6, S7, and S8 correspond to the first closing means of the present invention, step S1 corresponds to the opening means of the present invention, and step S2 corresponds to the detecting means of the present invention. Correspondingly, the S5 step corresponds to the repeating means of the invention, and the S10 step corresponds to the second closing means of the invention.

In the above embodiment, during heating, cooling air for cooling the infrared detector 7 is supplied into the storage chamber 15, and if the opening 5 is open, the cooling air is passed through the opening 5 and into the heating chamber 2. If the infrared detector 7 is sent inside, water vapor, oil, etc. will be further prevented from reaching the infrared detector 7.

(E) Effects of the Invention As is clear from the above explanation, according to the present invention, during heating, temperature detection is performed by an infrared detector every certain period of time when the opening for allowing infrared rays to pass is opened. If the temperature difference between the detected temperature and the desired temperature is equal to or greater than a certain temperature difference, the opening/closing means closes the opening for the next certain period of time, while the temperature difference between the detected temperature and the desired temperature If the detected temperature is within a certain temperature, the opening/closing means closes the opening when the detected temperature reaches the desired temperature, thereby significantly preventing the infrared detector from being contaminated by water vapor, oil, etc. .

[Brief explanation of the drawing]

The drawings show a microwave oven according to an embodiment of the present invention; FIG. 1 is a sectional view, FIG. 2 is a plan view of main parts, FIG. 3 is a circuit diagram, FIG. 4 is a flowchart of a microcomputer program, and FIG. It is a heating temperature characteristic diagram of food. 2... Heating chamber, 5... Opening, 7... Infrared detector, 8... Shutter, 16... Microcomputer.

Claims (1)

[Claims] 1. An infrared detector for detecting the food temperature by receiving infrared rays from the food through an opening formed in the heating chamber wall, an opening/closing means for opening and closing the opening, and whether the temperature detected by the infrared detector has reached the desired temperature. In the cooking device, the control section includes a first closing means for closing the opening by the opening and closing means for a certain period of time, and a first closing means for closing the opening by the opening and closing means for a certain period of time, and a first closing means for closing the opening by the opening and closing means for a certain period of time, and a first closing device that closes the opening by the opening and closing device for a certain period of time, and a first closing device that closes the opening by the opening and closing device for a certain period of time, and a first closing device that closes the opening by the opening and closing device for a certain period of time. an opening means for opening the opening by a means; a detection means for detecting the food temperature using the infrared detector when the opening is made; and a temperature between the desired temperature and the food temperature detected by the detection means. a repeating means for repeating the control of the first closing means, opening means and detecting means, and a temperature difference between the desired temperature and the food temperature detected by the detecting means, if the difference is a certain temperature difference or more; is within the certain temperature difference, a second closing means closes the opening with the opening and closing means when the food temperature detected using the infrared detector reaches the desired temperature. A cooking device characterized by having: