JPS62165893A - Heating cooker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heating cooker such as a microwave oven, and in particular, to a heating method using an infrared detector to detect the surface temperature distribution of a heated object and determine the heat source. Regarding cooking equipment.

[Conventional technology]

Cooking devices such as microwave ovens are equipped with various sensors to detect the condition of the object to be heated (food), and these sensors are combined with a microcomputer to cook food that adapts to the moment-by-moment condition of the food. is being carried out. In particular, a method is often used in which an infrared detector detects infrared rays emitted from an object to be heated, converts the detected infrared rays into a temperature, and controls a heat source such as a magnetron based on the detected temperature.

[Problem that the invention seeks to solve]

However, temperature detection using an infrared detector has the following problems. The field of view of the infrared detector is fixed to a certain set area on the turntable, and the infrared detector detects the average temperature of the heated object placed within the field of view. In this case, depending on the size of the object to be heated and the position at which it is placed, the object to be heated may not be completely within the field of view of the infrared detector, and in such a case, accurate temperature detection cannot be performed.

On the other hand, if the field of view of the infrared detector is made sufficiently large, if the object to be heated is small, the surface of the turntable will come within the field of view, making accurate temperature detection impossible.

In addition, in microwave ovens, the object to be heated is rotated using a turntable to prevent uneven heating, but if the object is large, uneven heating may occur even if the object is rotated in this way, resulting in differences in surface temperature. may occur. However, in the past, only the averaged temperature of the entire surface of the object to be heated can be detected, so controlling the heat source based on this can be problematic depending on the type of food and cooking method. For example, when cooking sashimi to defrost, the edges of the sashimi thaw the fastest, so with the conventional method of turning off the heat source when the overall average temperature reaches the set temperature, the edges of the sashimi may partially thaw. It will become boiled and cause discoloration.

In other words, when thawing and cooking sashimi, it is necessary to focus on the temperature of the hottest part of the cooking process, but with conventional technology, only the averaged temperature is detected, so there is little temperature variation. There was a problem with not being able to cook properly.

The present invention has been made in view of these problems, and an object of the present invention is to provide a heating cooker that can detect the surface temperature distribution of a heated object and perform defrosting and cooking at a uniform temperature based on the detected surface temperature distribution. purpose.

Means for Solving Problem C] In order to achieve this object, the present invention detects infrared rays emitted from an object to be heated on a turntable using a plurality of infrared detectors, and detects the outputs of these infrared detectors. The surface temperature distribution of the object to be heated is determined from the signal, and when at least a part of the area in this surface temperature distribution reaches a first set temperature or higher, the heat source for heating the object to be heated is turned off, and the first
The heat source is characterized in that the heat source is turned on when the temperature falls below a second set temperature, which is lower than the set temperature.

Here, a plurality of infrared detectors are arranged, for example, in the radial direction of the turntable. In that case, by capturing each output signal of the infrared detector in synchronization with the rotation of the turntable, the surface temperature distribution of the object to be heated in the radial direction of the turntable can be determined.

[Effect]

According to the invention, at least one of the plurality of infrared detectors
When the temperature detected by each detector exceeds the first set temperature, the heat source is turned off, and when the temperature falls below the second set temperature, the heat source is turned on again. After such operations are repeated, if the temperature detected by all the infrared detectors does not fall below the set temperature with the heat source turned off for a set period of time, cooking such as defrosting cooking ends.

(Example) The present invention will be described in detail below. FIG. 1 shows a microwave oven as a cooking device according to an embodiment of the present invention, in which (a) is a perspective view showing the external shape, and (b) is a sectional view schematically showing the internal structure. .

In FIG. 1, a microwave oven main body 1 has a heating seedling 3 that is opened and closed by a door 2 provided at the front, and a turntable 5 that rotates with an object to be heated 4 placed on the bottom of the heating chamber 3.
is provided. The turntable 5 is rotationally driven by a motor 7 via a rotating shaft 6 inserted through the bottom surface of the heating chamber 3 . A magnetron as a heat source (not shown) is placed above the heating unit 3, and heating is performed by emitting microwaves from the magnetron toward the object 4 to be heated. An operation panel 8 is provided on the front side of the microwave oven main body 1, and various operation switches 9 and a display section 10 are arranged on the operation panel 8.

By operating the operation switch 9, the intensity and irradiation time of the microwave irradiated to the heated object 4 are set, and the surface temperature of the heated object 5 detected by the temperature detector built into the microwave oven main body 1 is displayed. The screen is configured to be displayed by the section 10.

A plurality of infrared detectors 118 to 11g, seven in this example, are provided on the ceiling of the heating v3.

As shown in FIG. 2, the infrared detectors 11a to 11Q include a so-called thermal infrared sensor element 12, such as a thermopile or thermistor bolometer, which converts the element temperature increased by infrared rays into an electrical signal, and a sensor element 12 in front of the infrared sensor element 12.
and a horn 13 for limiting the field of view of infrared rays incident on the infrared rays, and are mounted on a common support 14.

The thermal infrared sensor 12 detects its own temperature and the heated object 4.
The output is proportional to the temperature difference between the surface temperature and the surface temperature. For this reason, in this embodiment, the support body 14 is further provided with a temperature sensor 15 such as a thermistor that detects the temperature of the sensor element 12 itself in the infrared detectors 11a to 110.
This temperature sensor 15 corrects the output of the infrared sensor element 12 to determine the surface temperature of the object 4 to be heated.

Here, the infrared detectors 118 to 11g are arranged in the radial direction of the turntable 5 as shown in FIG. 1(b), and as shown in FIG. It has a fixed field of view a-g.

The output signals of the infrared detectors 118 to 11g are amplified by amplifiers 16a to 16Q, respectively, as shown in FIG.
It is input to selector 1B. On the other hand, the temperature sensor 15 is connected to a detection circuit 17, which converts the resistance value of a thermistor or the like constituting the temperature sensor 15 into an electrical signal corresponding to the temperature, and then inputs the electrical signal to the selector 18. The selector 18 is controlled by the CPU 20 and sequentially selects the outputs of the amplifiers 168 to 16g and the detection circuit 17 and supplies them to one A/D converter. The A/D converter 19 is C
It is controlled by the PU 20 and sequentially digitizes the signals sent from the selector 18 and supplies them to the CPU 20.

The selector 18 and the A/D converter 19 constitute a signal processing means for determining the surface temperature distribution of the object to be heated 4, and the CPU 20
constitutes a control means for controlling the magnetron, which is a heat source, according to this surface temperature distribution. That is, the A/D converter 19 converts the amplifier 1 in synchronization with the rotation of the turntable 5.
68 to 16g and the output signals of the detection circuit 17 are sequentially taken in and converted into digital signals, and the CPU 20 supplies a control signal to the motor drive circuit 21 connected to the motor 7 for rotating the turntable 5. A switching signal is sent to the selector 18 in synchronization with the rotation of the motor 6.
A/D conversion commands are supplied to each A/D converter 19, and further, based on the signal from the A/D converter 19, the heated object 4 is
The magnetron is controlled on/off by determining the surface temperature distribution.

Next, the operation of this embodiment will be explained with reference to the signal waveform diagram shown in FIG. Taking as an example the case where the object to be heated 4 is food such as frozen sashimi having a shape as shown in FIG. 6, the turntable 5 is rotated in the direction of the arrow shown in FIG. 3, and then, after a slight delay, the magnetron is driven to start microwave irradiation.

On the other hand, the output signals from the infrared detectors 118 to 11g are
After being amplified by the amplifiers 168 to 16g, the signals are sequentially input to the A/D converter 19 via the selector 18, converted into digital signals, and then taken into the CPU 20. Further, temperature data of the infrared sensor 12 itself detected via the temperature sensor 15 and the detection circuit 17 is also appropriately taken into the CPtJ 20 via the selector 18 and the A/D converter 19.

Here, the CPU 20 sets the time for one rotation of the turntable 5 (T shown in FIG. 5) as the bottom, and when the preset angle is Δθ, the CPU 20 calculates the following for every time when □t=T・Δθ/360°. The output signals of the infrared detectors 11a to 11Q are amplified by amplifiers 16a to 16G, and the data shown in FIGS. 5A to 5G, which are digitized by an A/D converter 19 via a selector 18, are sequentially taken in. For example, if T=15 seconds (this time is determined by the specifications of the motor 6) and Δθ=24°, then t=1 second. Data A to G captured in this way
is corrected as described above by the temperature data of the infrared sensor 12 itself detected by the temperature sensor 15 and the detection circuit 17 and taken in via the selector 18 and A/D converter 19, and the surface temperature of the heated object 4 is Distribution is required.

In thawing cooking, thawing usually progresses from the surface of the object to be heated 4.
The temperature difference between the surface and the inside increases. Therefore, the temperature of each region in the surface temperature distribution obtained as described above (the temperature corresponding to each of data A-G) is compared with a predetermined first set temperature T1 (for example, +5°C), and When at least a part of the area in the surface temperature distribution reaches the first set temperature T1 or higher, the magnetron is turned off. As a result, the surface temperature of the object to be heated 5 starts to decrease again due to the influence of the lower internal temperature.

Next, the temperature of each area in the surface temperature distribution is compared with a second set temperature T2 (for example, -3°C) lower than T1, and at least a part of the area in this surface temperature distribution is below this second set temperature. When it becomes 2 or less, turn on the magnetron again. As a result of repeating these actions,
When the temperature does not drop below the second set temperature by 2 below even if the magnetron is turned off for a set period of time or longer, the thawing cooking ends.

By thawing and cooking in this manner, it is possible to prevent the frozen sashimi, etc., which is the object to be heated 4, from becoming partially heated at the edges and becoming boiled, causing discoloration.
Good results are obtained.

Note that when the object to be heated 4 is small, the object to be heated 4 does not enter the field of view of the outermost infrared detector 1''IQ in FIG. As shown in FIG. 5G, the temperature detected by 11g indicates a high temperature (near the air temperature) set during the rotation of the turntable 5, and the surface temperature of the heated object 4 is higher than the first set temperature T1. In such a case, if you determine the initial values of data A to G at the start of cooking and do not use that data when the temperature is extremely high, you can prevent incorrect control due to such misidentification. This can be prevented and cooking can be done correctly.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of infrared detectors are used to determine the surface temperature distribution of the object to be heated on the turntable, and based on that, the heat source is controlled to turn on and off. Good thawing and cooking can be performed without partially boiling or discoloration of the food.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are perspective views showing the external appearance and a sectional view schematically showing the internal structure of a microwave oven, which is a heating cooker according to an embodiment of the present invention, and FIG. 2 is a sectional view schematically showing the internal structure FIG. 3 is a plan view illustrating the positional relationship between the object to be heated on the turntable and the field of view of the infrared detector in the same embodiment, and FIG. 4 is a diagram showing the configuration of the infrared detector in the same embodiment. FIG. 5 is a diagram showing the configuration of the electronic circuit section, and is a signal waveform diagram for explaining the operation of the same embodiment. 3... Heating, 4... Heated object, 5... Turntable, 6... Motor, 11a-IIQ... Infrared detector, '12... Infrared sensor element, 13... -Horn, 14...Support, 15...Temperature sensor, 16
a~16g...Amplifier, 17...Detection circuit, 18.
...Selector, 19...A/D converter, 20...C
PU, 21...Motor drive circuit. Applicant's agent Patent attorney Takehiko Suzue (b) Figure 2 1''3 Figure 4vA Figure 5

Claims (2)

[Claims] (1) A heating cooker that heats an object placed on a turntable, including a plurality of infrared detectors that detect infrared rays emitted from the object to be heated on the turntable, and a signal processing means for determining a surface temperature distribution of the object to be heated from an output signal of an infrared detector; and at least a part of the area in the surface temperature distribution determined by the signal processing means is equal to or higher than a first set temperature. When the heat source for heating the object to be heated is turned off,
A heating cooker comprising: control means for turning on the heat source when the temperature reaches a second set temperature that is lower than the first set temperature. (2) The plurality of infrared detectors are arranged in the radial direction of the turntable, and the signal processing means synchronizes the output signals of the plurality of infrared detectors with the rotation of the turntable. 2. The cooking device according to claim 1, wherein the surface temperature distribution is determined by taking in the surface temperature distribution.