JP2515118B2 - Heating cooker - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating cooker for heating an object to be heated,
In particular, the present invention relates to a heating cooker having a function of detecting a change in the reflectance of the surface of an object to be heated during heating and automatically controlling browning cooking of the object to be heated.

2. Description of the Related Art In heating cookers such as electric ovens, gas ovens, and microwave ovens that heat an object to be heated stored in a heating chamber to cook it, the judgment of the degree of burning of the object to be heated has been more difficult than before. It was set as a rough guide by setting the timer or by setting the timer time by experience. In any case, however, the desired browning time differs depending on the amount, moisture content, composition, shape, etc. of the object to be heated, so there is the drawback that it is necessary to constantly monitor for proper burning. It was

As means for removing this troublesome defect, there has been considered a method for appropriately automatically controlling the browning of the object to be heated. That is, as shown in, for example, Japanese Patent Laid-Open No. 55-89629, a light source for irradiating an object to be heated in the heating chamber with visible light is provided, and the reflected light from the surface of the object to be irradiated of this irradiation light is received by a light receiving element. It detects and controls the heating source when the illuminance of reflected light reaches a preset value.

Problems to be Solved by the Invention Although this detection method is excellent in principle, it has the following problems in practical use.

That is, in this method, the illuminance of the reflected light continuously decreases as the occurrence of charring progresses, but at the stage of detecting the charred eyes, high-intensity disturbance light such as natural light suddenly emerges from the window of the cooker in the heating chamber. When entering, the illuminance of the reflected light suddenly changes due to the influence of this ambient light, which not only makes it impossible to detect the burning, but also causes the food that is the object to be heated to be uncontrolled. There were also safety problems such as carbonization and smoke generation.

Means for Solving the Problems An object of the present invention is to solve the above problems and to provide a highly stable cooker with a browning detection function that prevents abnormal overheating of an object to be heated, Therefore, the change of reflected light is constantly monitored, and the heating control means for controlling the heating when the detection signal suddenly changes is set.

Action Measures the change in reflected light illuminance over time, calculates the average value of reflected light illuminance during one rotation of the mounting table, compares the calculated average value for each cycle, and the change range of the average value exceeds the setting range. Control codling heating.

Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram illustrating the configuration of the heating cooker of the present invention. In this embodiment, the high frequency heating function is provided, but the heating cooker according to the present invention is not limited to such a high frequency heating method.

In the figure, reference numeral 1 is a heating chamber in which a food 3 which is an object to be heated is put in a container 2 and placed on a rotary mounting table 4, which is rotated by a motor 5. Electric heaters 6a and 6b are located on the ceiling and the bottom of the heating chamber 1 to generate infrared energy and brown the food 3 by its radiant heat. Further, as another heat energy source into the heating chamber 1, a magnetron 7 is coupled to the heating chamber 1 by a waveguide 8.
Reference numeral 9 is an opening of the waveguide.

A light source lamp 10 for irradiating the food 3 with visible light is attached to the side wall of the heating chamber 1, and the food 3 is irradiated with visible light through the see-through window 11a. The light reflected from the food 3 is detected by the light receiving element 12 through another transparent window 11b. Light receiving element 12
For example, a photodiode is used for this. Light receiving element
The detection signal of 12 is amplified by the amplifier 13, and then the A / D
It is converted into a digital signal by the converter 14 and sent to the microcomputer 15. 16 is a microcomputer
There are 15 power supplies.

On the other hand, below the rotary mounting table 4, there are a motor 5 and a speed reduction mechanism (not shown), and the rotary mounting table 4 is mounted via the shaft 17.
It is a mechanism to rotate. A disc 18 with a notch or a marker is arranged on the shaft 17, and the rotation state of the mounting table is measured by a rotation detecting element 19 such as a photocoupler. Reference numeral 20 is a signal processing circuit of a rotation detecting element. The rotation detecting signal amplified and A / D converted is a microcomputer.
Sent to 15.

The microcomputer 15 sequentially adds the digital signals, that is, the converted signals of the reflected light received by the light receiving element 12, and counts the number of additions, and also detects the detection signal during one rotation of the mounting table based on the rotation detection signal. Calculate the average value of. The average value is calculated every one rotation of the mounting table, its change with time is obtained, and when the detection signal level drops from the initial value before heating to a preset level, the controller is instructed by the microcomputer 15
21 is operated to stop the heating operation of the heaters 6a and 6b. This makes it possible to detect dark eyes. At this stage of detecting dark spots, artificial light from a light bulb or the like is used as the visible light with which the food 3 is irradiated, but when the power supply voltage changes, the illuminance of the irradiation light changes, and as a result, the reflected light also changes, To maintain the detection accuracy, a constant voltage power supply is used or a voltage stabilizing means is used. However, when disturbance light with high illuminance, such as natural light, suddenly enters from the door surface during the stage of actually detecting the dark spot, the illuminance of reflected light may suddenly change under the influence. For example, the change curve 24 of the detection signal at the normal time in FIG. 2 has a change as shown by the curve 25 at the abnormal time. I.e. time t ₀
The heating is started from the illuminance detection signal V ₂ at, and the illuminance detection signal gradually decreases with the occurrence and progress of the dark spots.
It is assumed that, for example, ambient light enters at the point P ₁ when changing toward the set point value (illuminance detection signal for heating control) V ₁ indicating an appropriate dark point. This disturbance light is added to the incident light that had been applied to the food and is incident on the food, so the reflected light inevitably increases, and as a result, the illuminance detection signal is
Reach P ₁ to P ₂ . If heating is sustained and in this state, although the illuminance detection signal is reduced again, does not reach the set value V _1, it becomes dangerous state indefinitely be sustained heating.

Therefore, the following signal processing means is added to FIG. 1 to control heating.

That is, after the microcomputer 15 calculates the average value of the detection signal for each rotation of the mounting table by the above method, the average value in the second rotation is compared with the average value in the first rotation, and the average value in the second rotation is calculated. If smaller, continue heating. After that, this operation is repeated and heating is stopped when the average value reaches a preset value. On the other hand, when the average value exceeds the previously measured value and it is determined that the state is maintained, the microcomputer 15 stops measuring the average value and instructs the controller 21 to stop heating, as a result,
The heating operation is stopped. If the average value exceeds the previous measurement, the range of allowable values is about twice the average value.

Reference numeral 22 in FIG. 1 is a RAM, which is used for the purpose of reading and accumulating the darkness measurement information, reading the data, and calculating the average value. In addition, numeral 23 is a digital switch, and by using these switches, it is possible to set the multi-stage darkness.

FIG. 3 is a flow chart showing a method for controlling burn detection according to the present invention.

First, the set values for the browning are stored in RAM in advance, and the food is heated by the heater heating. Next, the added value of the illuminance detection signal during one rotation of the rotary mounting table is obtained and divided by the number of measurements to obtain the average value. This measurement is repeated thereafter, and when the average value of the illuminance detection signal reaches the preset set value of the dark spot, the heating source is controlled and the dark spot detection is completed. In the process of detecting the dark eye, if the average value of the subsequent detection signal is larger than the average value of the previous detection signal, that is, n-1
The detection signal Mn−1 for the second time and the detection signal Mn for the nth time are Mn ≧ 2Mn
When it becomes -1, the subsequent measurement of the detection signal is stopped and the heating is stopped.

FIG. 4 is a schematic diagram showing the ports of the RAM 22 in FIG. The RAM 22 temporarily stores data such as the added value of the illuminance detection signal, the count value of the number of times of measurement, the average value of the detection signal, and the set value of the dark spot, and transferred to the microcomputer.

In the embodiment, the case where the illuminance detection signal increases has been described, but in the case where the illuminance detection signal suddenly decreases, it does not cause any trouble because it quickly reaches the set value for the burnt eyes. However, if the signal pulsates violently during signal measurement, it is effective to detect a sudden drop and take the same measures as above.

EFFECTS OF THE INVENTION According to the present invention, in the method of automatically controlling the heating by detecting the browning by measuring the change of the reflected light due to the heating of the food, which is the object to be heated, Since the heating means is controlled correspondingly,
Even if the burn detection signal suddenly increases due to, for example, ambient light, overheating due to the inability to detect the burn is prevented, so that safety is ensured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a burn mark detection system for a heating cooker showing an embodiment of the present invention, FIG. 2 is a characteristic diagram for explaining the present invention, and FIG. 3 is a diagram showing the control procedure. A flow chart and FIG. 4 are explanatory views showing the RAM port. 1 ... Heating room, 3 ... Food, 10 ... Light source lamp, 12 ... Light receiving element, 15 ... Microcomputer, 21 ... Controller.

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. A heating means for heating an object to be heated in a heating chamber to form a brown mark, a rotary mounting table for mounting the object to be heated, a light source for irradiating the object to be heated with visible light, and reflected light from the object to be heated. And a detection means for detecting the illuminance, and the average value of the detection signals in a heating cooker configured to control the heating means when the reflected light illuminance detection signal detected by the detection means reaches a preset value. And a means for controlling the heating source when the average value of the detection signals is larger than the average value measured in the previous one cycle and exceeds the allowable width. And cooker.