JP2001004147A - Microwave oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce in size a temperature detecting structure, to facilitate disposing and designing and to improve a temperature measuring accuracy by detecting a temperature distribution, detecting a food state based on its detected result, and controlling to heat according to the detected result. SOLUTION: A magnetron 10 of a microwave generator is disposed in a machine room 1a. A temperature sensor 16 is provided in an upper portion of the room 1a to detect a surface temperature of food in a heating chamber 4. The sensor 16 has an infrared sensor element in a sensor case and an image focusing lens in an incident portion of the element. A control circuit 18 has a microcomputer to detect a temperature distribution. Signals from a photointerrupter 13, the sensor 16 and a key input unit 20 are input to the circuit 18. The circuit 18 functions as a food state detecting means for detecting a size and number of food and functions as a control means for controlling the magnetron 10, a motor 5 and correcting a set temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven having an improved temperature detecting structure.

[0002]

Conventionally, in a microwave oven, the temperature of food is detected by an infrared sensor,
The microwave generator is controlled according to the detection result. In this case, an infrared sensor is provided movably in the lateral direction above the upper plate portion of the heating chamber, and a sensor hole is formed in the upper plate portion along the moving direction, and the infrared sensor is moved while moving. The temperature in the heating chamber is detected in a relatively wide range through the sensor hole. However, in this case, a moving device for exclusively moving the infrared sensor is required, so that the installation space is widened and the configuration is complicated, and there is a problem that the whole configuration is enlarged and complicated.

[0003] As another configuration in which the moving device is not required, a temperature detecting device in which a plurality of infrared sensor elements are arranged is fixedly disposed above an upper plate portion of a heating chamber.
In some cases, a sensor hole is formed in opposition to the temperature detection device, and the temperature detection device detects a heating chamber in a relatively wide range. However, in this device, it is necessary to separate the element intervals to some extent so that the individual detection fields of view of the infrared sensor element do not overlap so much, the temperature detection device is relatively large, the installation space is widened, and the layout design is troublesome, In addition, there is a problem that the whole configuration becomes large and complicated. Moreover, the directionality of each infrared sensor element is also required to be accurate, which may cause a bias in the distribution of measurement points, which may lead to a reduction in temperature measurement accuracy and, consequently, a reduction in control reliability. Furthermore, the sensor hole is large, and there is a problem of microwave leakage.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce the size of a temperature detecting structure, to reduce an arrangement space and to facilitate an arrangement design, and to improve the temperature measurement accuracy. It is an object of the present invention to provide a microwave oven which can improve control reliability and control reliability.

[0005]

According to the first aspect of the present invention, there is provided a heating chamber for accommodating food, a microwave generator for supplying the microwave into the heating chamber to heat the food, and a plurality of infrared sensor elements. And a temperature detecting means provided with an imaging lens on the incident side of the plurality of infrared sensor elements, and a temperature distribution in the heating chamber based on a detection result of each of the infrared sensor elements by the temperature detecting means. A temperature distribution detecting means for detecting a temperature, a food form detecting means for detecting a food form based on a detection result from the temperature distribution detecting means, and a control means for performing heating control based on the detection result by the food form detecting means. It is comprised including.

According to the first aspect of the present invention, the temperature detecting means has a structure in which a plurality of infrared sensor elements are arranged and an imaging lens is provided on the incident side of the plurality of infrared sensor elements. Even if the sensor elements are arranged close to each other, a wide detection field of view can be secured, so that the size of the temperature detecting means can be reduced, the installation space can be reduced, and the layout design can be improved. Since the infrared rays from the heating chamber are optically incident on each infrared sensor element by the imaging lens, the infrared rays at the measuring point can be guided well without requiring high directivity to each infrared sensor element. Unlike the case where the sensor element is directly directed to the measured point, the uniformity of the distribution of the measured points can be improved, and the accuracy of temperature measurement and thus the reliability of control can be improved. It will be able to be achieved.

According to a second aspect of the present invention, the heating chamber is provided with a rotating body which is rotated by the driving means, and the food is arranged on the rotating body. The elements are arranged substantially linearly so as to have a detection field of view in the radial direction of the rotating body.
The rotator is driven to rotate, the detection result from each infrared sensor element of the temperature detecting means is measured for each predetermined rotation angle position, and based on the temperature measurement result at the measurement point for each predetermined rotation angle position of each infrared sensor element. The feature is that the temperature distribution is detected.

According to the second aspect of the present invention, the rotating body is driven to rotate, the detection result from each infrared sensor element of the temperature detecting means is measured at each predetermined rotation angle position, and the predetermined rotation angle position of each infrared sensor element is measured. Since the temperature distribution is detected based on the temperature measurement result at each measurement point, even if the number of infrared sensor elements is small, the temperature distribution of almost the entire heating chamber can be detected satisfactorily.

According to a third aspect of the present invention, the food form detecting means comprises:
For each measurement point, an area index that increases with distance from the center of the rotating body is set, and the food is present by comparing the temperature measurement result at each measurement point by the temperature distribution detection means with the reference temperature for food presence / absence determination. The feature is that the area of the food is detected by detecting the measurement points and summing up the area indexes for each of the measurement points. According to the third aspect of the invention, the area of the food can be accurately detected. That is, the presence or absence of food can be detected by comparing the measured temperature at the measurement point of each infrared sensor element with the reference temperature for food presence / absence determination. Incidentally, the area of the food may be obtained by multiplying the number of measurement points of the infrared sensor element indicating the temperature at which the food is present by the visual field. In this case, the detection fields of view of the plurality of infrared sensor elements are all substantially the same area (width). However, the measurement points of the infrared sensor elements that detect the rotation center side have a short rotational displacement distance, so that the detection visual fields overlap. Therefore, [the number of measurement points with food × the area of the detection visual field area] The actual food area, not the area, is smaller. Conversely, as the distance from the rotation center increases, the rotational displacement distance between the measurement points of the infrared sensor elements increases, and the degree of overlap of the detection visual field decreases. Number × area of detection visual field region] is close to the actual food area.

According to the third aspect of the present invention, the food form detecting means sets an area index for each measuring point that increases as the distance from the center of the rotating body increases. The temperature measurement result in is detected by comparing the food presence or absence determination reference temperature with the measurement point where the food is present, and the area of the food is detected by summing the area index for each measurement point. Therefore, the area of the food can be accurately detected.

According to a fourth aspect of the present invention, the food form detecting means comprises:
The number of foods is detected based on the number of times that the temperature measurement result at the measurement point obtained by the temperature distribution detecting means shows the characteristic of rising and falling in the rotating direction of the rotating body or the characteristic of changing to the opposite. It has a characteristic where it is. When the food is placed on the rotating body and heated, the temperature of the food increases with respect to the temperature of the rotating body. Therefore, a temperature difference is observed between the food existing portion and the food existing portion. By measuring the number of times the characteristic indicating the temperature difference appears, the number of foods can be detected (for example, in the case of one time, one food).

According to the fourth aspect of the present invention, the food form detecting means has a characteristic that the temperature measurement result at the measuring point obtained by the temperature distribution detecting means rises and falls in the rotating direction of the rotating body or vice versa. Since the number of foods is detected based on the number of times showing the changing characteristics, the number of foods can be accurately detected.

In this case, the food form detecting means may stop driving the microwave generator during a required period for detecting the number of foods (the invention of claim 5). By doing so, the temperature characteristics change is small during the required period, and the characteristics described above appear accurately, thereby improving the detection accuracy of the number of foods.

According to a sixth aspect of the present invention, when the food form detecting means detects that the number of foods is plural,
It is characterized in that the average temperature of the highest temperature of each food region is calculated and the microwave generator is controlled according to the average temperature.

When the number of foods is plural, the degree of heating may be different between one food and the other food.
In this case, if the heating control is performed based on the higher temperature of the food (for example, if the control of stopping the microwave generator is performed when the temperature reaches the set temperature), the heating of the other food is insufficient. Will be. Conversely, if the heating control is performed based on the other food having a low food temperature, one of the foods may be overheated.

According to the invention of claim 6, when the food form detecting means detects that the number of foods is plural, the average temperature of the maximum temperature of each food region is calculated, and the micro temperature is calculated according to the average temperature. Since the wave generator is controlled, a plurality of foods can be heated without excess or shortage.

According to a seventh aspect of the present invention, when the food form detecting means detects that the area of the food is equal to or greater than a predetermined value, the control means calculates an average temperature of the food and generates microwaves in accordance with the average temperature. The feature is that the device is controlled. When the size of the food is large, a large number of ingredients may be included (for example, a relatively large food includes a commercially available bento). In this case, if the heating control is performed based on the high temperature part (for example, if the control that stops the driving of the microwave generator when the temperature reaches the set temperature is performed), the heating of the other parts becomes insufficient. Would. However, in the invention of claim 7, since the average temperature of the food is calculated and the microwave generator is controlled according to the average temperature, insufficient heating of the whole food can be prevented.

The invention of claim 8 is characterized in that a position detecting means for detecting a rotation reference position of the rotating body is provided. According to the present invention, the detection of the rotational angle position of the rotating body becomes accurate, and the detection by the temperature distribution detecting means can be started from the always determined angular position, so that the accurate temperature distribution can be detected.

According to a ninth aspect of the present invention, the heating chamber is formed by a box, and a slit-shaped hole for temperature detection is formed at an upper portion of the box, and a hole corresponding to the hole is formed at an outer upper portion of the box. This is characterized in that the temperature detecting means is provided.

In the present invention, the temperature detecting means detects the temperature in the heating chamber through the hole from outside the heating chamber. If this hole is large, microwaves inside the heating chamber may leak. However, in the present invention, as described above, the temperature detecting means uses the imaging lens to transmit infrared rays from the heating chamber to each infrared sensor. Since the light is optically incident on the element, the hole may be a small slit-shaped hole, and microwave leakage can be prevented.

According to a tenth aspect of the present invention, there is provided a cooking end temperature setting means for setting a cooking end temperature, and when the cooking end temperature is set by the cooking end temperature setting means, the set cooking end temperature is set. An end determination reference temperature is set for each infrared sensor element according to the temperature, and the drive of the microwave generator is stopped when any of the plurality of infrared sensor elements reaches the end determination reference temperature. However, it has features.

If the cooking end temperature is set on the user's side and heating is stopped when the detected temperature of the food reaches the cooking end temperature, it is possible to heat and cook at a temperature desired by the user. However, when the distance to the detection target is long, each infrared sensor element of the temperature detection means may detect the temperature lower than the actual temperature. For example, if the temperature detecting means is located obliquely above the rotating body, the tendency of the infrared sensor element for detecting a portion near the center of the rotating body is stronger than that of other infrared sensor elements. For example, when the set cooking end temperature (temperature at which the heating operation is stopped) is 60 ° C., the detected temperature is 58 even if the actual food temperature is 60 ° C.
° C and the heating operation is not stopped. In this case, when the detected temperature reaches 60 ° C and the heating operation is stopped, the temperature of the food already exceeds 60 ° C. Further, when the temperature detected by the infrared sensor element is higher than the actual food temperature, insufficient heating is caused.

According to the tenth aspect of the present invention, when the cooking end temperature is set by the cooking end temperature setting means, the control means determines the end of each infrared sensor element according to the set cooking end temperature. A reference temperature is set, and when one of the plurality of infrared sensor elements reaches the end determination reference temperature, the operation of the microwave generator is stopped, thereby preventing overheating and insufficient heating of food. become able to.

The invention according to claim 11 is provided with cooking end temperature setting means for setting a cooking end temperature, wherein the control means detects when a high temperature portion is detected in a portion other than the center of the rotating body by the food form detecting means. Detecting the degree of temperature rise of the high temperature portion while the rotating body is rotating, and determining the high temperature portion from the temperature of the high temperature portion and the degree of temperature rise by the cooking end temperature setting means. The rotation angle position of the rotator reaching the end temperature is determined, and the drive of the microwave generator is stopped and controlled at the rotation angle position.

When the user sets the cooking end temperature and stops heating when the detected temperature of the food reaches the cooking end temperature, the highest temperature of the food becomes the cooking end temperature. It is sometimes preferable to stop heating. By the way, when the high temperature portion is near the center of rotation, the temperature change of the high temperature portion can be detected at any rotational angle position of the rotating body when the rotating body is rotated to detect the temperature distribution. Heating may be stopped when the temperature of the high temperature portion reaches the cooking end temperature. However, if the high-temperature portion exists in a portion other than the center portion of the rotating body, the temperature of that portion can be detected only at a timing of one rotation per rotation of the rotating body. However, at the next detection timing, it is possible that the temperature has already exceeded the cooking end temperature, and even if the heating is stopped, the cooking is overheated. Such a problem also occurs when a high-temperature portion appears in the peripheral portion of the food or when the food placed in a relatively small container such as a glass is disposed in the peripheral portion of the rotating body.

According to the present invention, when the high-temperature portion is detected in a portion other than the center portion of the rotating body by the food form detecting means, the control means detects the high temperature during rotation of the rotating body. Detect the temperature rise of the temperature part,
From the temperature of the high temperature portion and the degree of temperature rise, the rotation angle position of the rotating body at which the high temperature portion reaches the cooking end temperature set by the cooking end temperature setting means is determined, and the rotation angle position is calculated. Since the drive of the microwave generator is controlled to be stopped, even when the temperature detection timing for the high temperature portion can be obtained only once per rotation, the food reaches the cooking end temperature. Heating can be stopped at a point in time, and overheating can be reliably prevented.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First, in FIG. 1, the main body 1 of the microwave oven is configured by arranging an inner box 3 as a box inside an outer box 2.
Is a heating chamber 4. A motor 5 as a driving means is disposed below the center of the outer surface of the bottom plate portion 4a of the heating chamber 4, and the upper end of the rotating shaft 6 penetrates through the bottom plate portion 4a and is inside the heating chamber 4. It protrudes.

A rotating body 7 made of metal is detachably attached to the rotating shaft 6 so that the rotating body 7 can rotate integrally. Food is placed on the rotating body 7 directly or via a rotating dish 8 made of, for example, heat-resistant glass.

Further, the bottom plate 4a of the heating chamber 4 is
As shown in FIG. 2, a rectangular excitation port 9 is formed, for example. A space on the right side between the outer box 2 and the inner box 3 is a machine room 1a, and a magnetron 10 as a microwave generator is disposed in the machine room 1a. In this case, the antenna 10a faces downward.

Further, the bottom plate 4a of the heating chamber 4 has
A waveguide 11 is attached, and one end of the waveguide 11 surrounds the antenna 10 a of the magnetron 10, and the other end is configured to communicate with the excitation port 9.

On the other hand, on the rotating shaft 6 of the motor 5,
As shown in FIG. 7, the position detecting device 1 as a position detecting means
2 are provided. The position detecting device 12 includes a photo-interrupter 13 attached to the upper surface of the motor frame 5a which is a non-rotating part, and a subject which is attached to the rotating shaft 6 via a disk 14 and detected by the photo-interrupter 13. 15. In this case, the timing at which the subject 15 is detected by the photointerrupter 13 is shown in FIG.
As shown in FIG. 7, the timing at which the specific position Ph of the rotating body 7 coincides with the specific position P4 of the heating chamber 4 is referred to as an initial position. In this case, the motor 5 is constituted by a synchronous motor, and is configured to be driven to rotate at a constant speed.

Further, in FIG. 1, a temperature sensor 16 as a temperature detecting means is disposed above the machine room 1a, and the temperature sensor 16 is formed on a side wall of the heating chamber 4 for detecting temperature. Through the hole 17, the surface temperature of the food in the heating chamber 4 is detected. The hole 17 is formed at an upper portion of a concave portion 17a formed on a side wall of the inner box 3, and has a slit shape as shown in FIGS. It is set short. As shown in FIGS. 5 and 6, the temperature sensor 16 has an infrared sensor element 16 inside a sensor case 16a.
1 to 166 are arranged in a line, and the imaging lens 1 is arranged on the incident side of these infrared sensor elements 161 to 166.
9 is provided. In this case, the infrared sensor elements 161 to 166 are arranged along the radial direction of the rotating body 7, of which the infrared sensor element 161 detects the central part of the rotating body 7 or the rotating plate 8, Elements 162, 163, 164, 165, 16
The outer peripheral side is detected in the order of 6. The detection visual fields of the infrared sensor elements 161 to 166 on the rotating plate 8 are as shown by reference numerals S1, S2, S3, S4, S5, and S6 in FIG.

The control circuit 18 includes a microcomputer, which detects a temperature distribution as follows. That is, the control circuit 18 has a timer function, and has, as data, the time th required for one rotation of the motor 5 at constant speed rotation. The control circuit 18
The rotating body 7 is rotated at a constant speed, and “360” of the rotating body 7 is determined based on the time count from the detection signal input of the photointerrupter 13 (the rotating angle position of the rotating body 7 is the initial position).
° / 16 ”rotation angle position (refer to symbols a to p in FIG. 10)
Is detected. At each rotation angle position, “1” in FIG.
There are ~ 6 measurement points, and thus there are 64 measurement points P (i, j) as a whole. Each time the rotation angle positions a to p are reached, each infrared sensor element 16
Point temperature T (i, j) from 1 to 166 (i = 1 to
6, j = a to p). The point temperature T (i, j), which is the result of the temperature measurement, is detected and stored as a temperature distribution by the control circuit 18. In other words, 64 point temperatures T (i, j) are taken in by one rotation of the rotating body 7, and the temperature distribution is detected.

In FIG. 3, signals from the photo interrupter 13, the temperature sensor 16 and the key input unit 20 are input to the control circuit 18. The key input section 20 includes keys such as a cooking end temperature setting key, a start key, and a reset key as cooking end temperature setting means. The control circuit 18 functions as a food form detection unit that detects the size (area) and the number of foods, and also functions as a control unit that controls the magnetron 10 and the motor 5 and corrects a set temperature. .

The functions of the food form detecting means and the control means will be described with reference to the flowcharts of FIGS. When food is placed on the rotating body 7 via the rotating plate 8 and the desired cooking end temperature Ts is set by operating the cooking end temperature setting key and the start key is operated, the flowchart of FIG. 11 starts. That is, the control circuit 18 first drives the magnetron 10 to start heating as shown in step V1, and drives the motor 5 to energize to rotate the rotating body 7.

Then, the process proceeds to step V2, where temperature distribution detection and food area detection are performed. Details of this step V2 are shown in a flowchart as a subroutine of FIG. In this flowchart, step W
In step 1, the temperature distribution is detected. That is, the point temperature T (i, j) detected by each of the infrared sensor elements 161 to 166 is read at each of the rotation angle positions a to p while rotating the rotating body 7 once. In this case, FIG. 13 shows the temperature changes of the point temperatures T (1, a) to T (6, a) of the infrared sensor elements 161 to 166 at the rotation angle position a. FIG. 13 shows, for example, the point temperatures T (1, a) to T (6, a) when the food F is arranged at the center of the rotating body 7 and thus the rotating plate 8 as shown in FIG.
Shows the change. As can be seen from FIG. 13, since the food F exists in the detection visual fields S1 and S2 of the infrared sensor elements 161 and 162 on the center side, the point temperature T
(1, a) and T (2, a) have a greater temperature rise than other parts (parts without food).

In the next step W2, the maximum temperature and the minimum temperature are detected from the point temperatures T (1, a) to T (6, p) for one rotation, that is, the temperature distribution detected this time, and the difference between them is determined. calculate. Then, in step W3, this temperature difference is 10
Determine if it is greater than ° C. The purpose of this decision is
When the temperature difference is 10 ° C. or more, it is based on the idea that it can be determined that there is food.

Thereafter, in step W4, all point temperatures T (1,
a) Calculate the average temperature Tav of T (6, p). Then, each point temperature T (i, j) is calculated from the average temperature Tav.
When it is determined that the measured point P (i, j) is larger than the measured point P (i, j), the process proceeds to step W6, and the measurement point P (i, j) is determined to be the food existence area.
j) and a parameter “1” indicating the presence of food is stored. And the point temperature T (i, j)
Is equal to or lower than the average temperature Tav, the process proceeds to step W7, where the measurement point P (i, j) is determined to be a food absence region, the measurement point P (i, j) is stored, and there is no food. Is stored.

When the comparison with the average temperature Tav is completed for all the point temperatures T (i, j) (step W)
8), the process proceeds to step W9, and each measurement point P (i, j) in the food existence region is multiplied by the area index K (i) and summed to detect the area S of the food. This area index K
The concept of (i) is as follows.

That is, in general, the area of the food may be obtained by multiplying the number of each measurement point P (i, j) in the food existing area by the area of the visual field. However, as shown in FIG. 10, the infrared sensor elements 161 and 1 for detecting the rotation center side are provided.
62 measurement points P (1, j), P
Since (2, j) competitors have a short rotational displacement distance, the detection visual fields overlap, so that [the number of measurement points with food × the area of the detection visual field area] is not the food area, but the actual food area is Smaller than this. Conversely, the infrared sensor elements 165 and 166 that are farther from the center of rotation have a smaller degree of overlap in the detection visual field because the rotational displacement distance between the measurement points is longer. (I, j), [the number of measurement points with food × the area of the detection visual field region] becomes closer to the actual food area.

In consideration of this, in this embodiment, as shown in FIG. 15, each of the measurement points P (1, j) to P (6, j)
Is set to an area index K (i) that increases as the distance from the center of the rotating body 7 increases. For example, the measurement point P (1, j) at the center has an area coefficient of “1”, and becomes “3”, “5”,
"7", "9", and the outermost measurement point P
In (6, j), “11” is set. As described above, in step W9, the area S of the food is obtained.

In the next step W10, based on the area S, it is determined that the size of the food is one of three levels. That is, as shown in FIG.
The food size is determined to be "small" when 0 to 90, "medium" when 91 to 140, and "large" when 141 to 240.
In addition, the food “small” includes foods placed in a vertical container such as a cup, the “medium” includes foods placed in a bowl, and the “large” foods placed on a plate. Is included.

Thereafter, the flow shifts to step V3 in FIG. 11 to determine whether the determined size is "large", "medium", or "small". The cooking end temperature Ts set by the user is corrected according to "small" (steps V4 to V6). For example, when the size of the food is “large”, the set cooking end temperature Ts is corrected to be lower (for example, lower by 2 ° C.). When the size of the food is “small”, the set cooking end temperature Ts is corrected to be higher (for example, 2 ° C. higher). In the case of "medium", no correction is made.

Thereafter, the process proceeds to step V7 to detect a temperature distribution. At step V8, it is determined whether the highest temperature among the detected temperature distributions exceeds the currently set or corrected cooking end temperature Ts. It is determined whether or not it exceeds, and if it exceeds, the process proceeds to step V9 to stop driving the magnetron 10, stop driving the motor 5, and end the heating control.

In this embodiment, the temperature detection sensor 16 is replaced by a plurality of infrared sensor elements 161 to 166.
And the infrared sensor elements 161 to 166
Since the imaging lens 19 is provided on the side of the incident portion, even if the infrared sensor elements 161 to 166 are arranged close to each other, a wide detection field of view can be secured.
The size of the temperature detection sensor 16 can be reduced, the installation space can be reduced, and the layout design can be improved. Further, the infrared rays from the heating chamber 4 are optically transmitted to the infrared sensor elements 161 to 166 by the imaging lens 19. , The infrared rays at the measurement point can be favorably guided without requiring high directivity to each of the infrared sensor elements 161 to 166, unlike the case where each infrared sensor element is directly directed to the point to be measured. In addition, the uniformity of the distribution of the measurement points can be improved, and the accuracy of the temperature measurement and thus the control reliability can be improved.

Further, according to the present embodiment, the rotating body 7 is driven to rotate, and the infrared sensor elements 161 to 16 of the temperature sensor 16 are provided at predetermined rotation angle positions (360/16 [degrees]).
6 are measured, and a plurality of measurement points P
Since the temperature distribution is detected based on the point temperature T (i, j) at (i, j), even if the number of infrared sensor elements 161 to 166 is small, the temperature distribution of almost the entire heating chamber 4 can be reduced. Can be detected well.

Further, according to the present embodiment, the area index K (i) that increases as the distance from the center of the rotator is set for each measurement point P (i, j) of each of the infrared sensor elements 161 to 166. , Each measurement point P (i,
By comparing the point temperature T (i, j) in j) with the average temperature Tav, which is a reference temperature for determining the presence or absence of food, a measurement point where food is present is detected, and an area index K (i) for each measurement point is detected. , The area of the food is detected, so that the area of the food can be accurately detected.

Further, according to this embodiment, the rotating body 7
Since the position detecting device 12 for detecting the rotation reference position is provided, the rotation angle position of the rotating body 7 can be accurately detected, and
Temperature distribution detection can be started from a fixed angle position, and an accurate temperature distribution can be detected.

The temperature sensor 16 is configured to detect the temperature in the heating chamber 4 from outside the heating chamber 4 through the hole 17. In this case, if the hole 17 is large,
Although there is a possibility that the internal microwave may leak, however, in this embodiment, the temperature detection sensor 16 is connected to the imaging lens 1.
9, the infrared rays from the heating chamber 4
Since the holes 17 are optically incident on the holes 61 to 166, the holes 17 may be small slit-shaped holes, and microwave leakage can be prevented.

FIGS. 17 to 20 show a second embodiment of the present invention. In this embodiment, the point temperature T (i, j) obtained by detecting the temperature distribution varies in the rotation direction of the rotating body 7. It is characterized in that the number of foods is detected based on the number of times that the characteristics of ascending and descending are shown. That is, in step X1 of the flowchart in FIG. 17, the magnetron 10 is driven to start heating, and the motor 5 is energized to rotate the rotating body 7.

Then, the process proceeds to step X2 to detect the temperature distribution and the number of foods. Details of this step X2 are shown in a flowchart as a subroutine of FIG. In this flowchart, step Y
Steps 1 to Y3 correspond to steps W1 to S
It is the same as W3, that is, the presence or absence of food is determined.

In the next step Y4, the magnetron 10
And the drive of the motor 5 is stopped, and in step Y5, the average temperature Tn (x) of the detected temperatures of the infrared sensor elements 161 to 165 at the respective rotational angle positions a to p is calculated. In this case, x is a variable 1 to 16 corresponding to the rotational angle positions a to p. For example, when the food contained in the cup is placed on the center of the rotating plate 8 (for example, see FIG. 14), the food shown in FIG.
As shown in FIG. 9, the average temperature Tn at each of the rotation angle positions a to p
(X) becomes uniform (no temperature difference). When a plurality of (in this case, three) foods are placed on one rotating plate 8 as foods, the average temperature Tn (x) varies.

Then, steps Y6 to Y10
Detects the number of times that the average temperature Tn (x) has a characteristic of rising and falling while the rotation angle position changes from a to p. That is, in step Y7,
A temperature difference before and after each of the rotation angle positions a to p is calculated, and in step Y8, it is determined whether or not the temperature difference has increased in a temperature range of 2 ° C. or more and decreased in a temperature range of 2 ° C. or more. 2 ℃
If it is determined that the movement has been raised and lowered, step Y
Then, the process proceeds to step 9 where the number of parameters N is incremented. This is performed 16 times (determined in step Y10), and the number of foods is detected based on the parameter N.
That is, when the parameter N is “0” or “1”, the number of foods is detected as “1”, and when N is “2” or more, it is determined that the number of foods is “N”. Here, in the case of FIG. 19, the number is “1”, and in the case of FIG. 20, x = 3, 9, 15 (that is, the rotational angle positions c, i,
Since the rise and fall of 2 ° C. or more are shown at the point o), the number of foods is detected as “3”. Then, the process proceeds to step Y12, where the magnetron 10 and the motor 5
Drive.

Thereafter, returning to step X3 in FIG.
It is determined whether or not the number is plural.
The process proceeds to step X4, step X5, and step X6. The purpose of steps X4 to X6 is to detect the maximum temperatures of the three food areas, calculate the average temperature thereof, and set the cooking end temperature T at which the average temperature is set.
If not less than s, the process proceeds to step X7 to stop driving the magnetron 10 and the motor 5, and ends the heating control. In this embodiment, the characteristic that rises and falls in the rotation direction of the rotating body 7 is detected. However, the characteristic that changes in the opposite direction may be detected.

According to the second embodiment, the average temperature of each of the infrared sensor elements 161 to 166 at each of the rotational angle positions a to p rises and falls in the rotation direction of the rotating body 7 or vice versa. Since the number of foods is detected based on the number of times N indicating the changing characteristics, the number of foods can be detected with high accuracy.

According to this embodiment, step Y
4. As can be seen from step Y12, since the driving of the magnetron 10 is stopped during the required period for detecting the number of foods, the change in the food temperature during the required period is small, and the above characteristics can be accurately displayed. Thus, the detection accuracy of the number of foods is improved.

Further, according to this embodiment, when it is detected that the number of foods is plural, the average temperature of the maximum temperature of each food area is calculated, and the set cooking end temperature Ts has reached this average temperature. Since the stop control of the magnetron 10 is sometimes performed, a plurality of foods can be heated without excess or shortage.

That is, when the number of foods is plural,
One food and the other food may have different degrees of heating. In this case, if the control for stopping the driving of the magnetron 10 is performed when the higher temperature of the food reaches the set cooking end temperature, the heating of the other food becomes insufficient. Conversely, if the heating control is performed based on the other food having a low food temperature, one of the foods may be overheated. However, this is not the case in this embodiment.

The present invention is not limited to the above embodiments, but may be implemented as follows. When it is detected that the area of the food is equal to or more than a certain value, the average temperature of the food may be calculated, and the microwave generator may be controlled according to the average temperature. The purpose of this is as follows. That is, when the size of the food is large, many foods may be included (for example, a relatively large food includes a commercially available bento). In this case, if the heating control is performed based on the high temperature part (for example, if the control of stopping the driving of the microwave generator when the temperature reaches the set temperature is performed), the heating of the other parts is insufficient. Will be. However, by calculating the average temperature of the food and controlling the microwave generator in accordance with the average temperature, insufficient heating of the whole food can be prevented.

When the cooking end temperature Ts is set by the cooking end temperature setting key, an end judgment reference temperature Ts' is set for each infrared sensor in accordance with the set cooking end temperature Ts (according to the present invention). The driving of the magnetron 10 may be stopped when any one of the infrared sensor elements 161 to 166 reaches the end determination reference temperature Ts ′ (see FIG. 21 shown as the third embodiment). The purpose of this is as follows. That is, the user sets the cooking end temperature Ts, and the detected temperature of the food is set to the cooking end temperature Ts.
If the heating is stopped at the time, the user can heat and cook at a temperature desired by the user. However, when the distance to the detection target is long, each of the infrared sensor elements 161 to 166 may detect lower than the actual temperature.
When the temperature sensor 16 is configured to be obliquely above the rotating body 7, the tendency of the infrared sensor element 161 for detecting a portion near the center of the rotating body 7 is stronger than that of other infrared sensor elements. In other words, when the set cooking end temperature Ts is 60 ° C., even if the actual food temperature is 60 ° C., the detected temperature of the infrared sensor element 161 is 58 ° C., and the heating operation is not stopped. , Detected temperature is 6
When the temperature reaches 0 ° C. and the heating operation is stopped, the temperature of the food already exceeds 60 ° C. However, with the above-described configuration, the food can be prevented from being overheated.

Further, as shown in FIG. 22 showing a fourth embodiment of the present invention, when a high temperature Th is detected in a portion H other than the center of the rotating body 7, the rotation of the rotating body 7 is stopped. The temperature rise degree ΔT of the high temperature portion H is detected, and the rotation at which the high temperature portion H reaches the set cooking end temperature Ts is determined from the temperature Th of the high temperature portion H and the temperature rise degree ΔT. The rotation angle position of the body 7 may be determined, and the drive of the magnetron 10 may be stopped and controlled at the rotation angle position. The temperature rise ΔT is calculated from the temperature difference during one rotation of the high temperature portion H. If the detected temperature of the high-temperature portion H is Tx, the temperature Tx 'of the portion H after the next one rotation is Tx' = Tx + ΔT × th. When it is determined that Tx ′ exceeds the cooking end temperature Ts (timing t0 in FIG. 23), the time tp at which Tx reaches the cooking end temperature Ts is calculated by tp = (Ts−Tx) / ΔT. When the time tp has elapsed from the timing t0, the driving of the magnetron 10 is stopped.

The purpose of such control is as follows. That is, when the user sets the cooking end temperature Ts and stops heating when the detected temperature of the food reaches the cooking end temperature Ts, the temperature Tx of the highest portion H of the food is the cooking end temperature. It is preferable to stop heating when the temperature reaches Ts. However, if the high temperature portion H exists in a portion other than the center portion of the rotating body 7, the temperature can be detected only at a timing of one degree per rotation of the rotating body 7, and at this detection timing, the temperature is lower than the cooking end temperature Ts. At the next detection timing, it is considered that the temperature has already exceeded the cooking end temperature Ts, so that even if the heating is stopped, the cooking will be overheated. Such a problem also occurs when a high-temperature portion appears in the peripheral portion of the food or when the food placed in a relatively small container such as a glass is disposed in the peripheral portion of the rotating body.

In this embodiment, however, the food has reached the cooking end temperature Ts by the above-described control even in a situation where the temperature detection timing for the high temperature portion H can be obtained only once per rotation. Heating can be stopped at a point in time, and overheating can be reliably prevented.

[0064]

As apparent from the above description, the present invention can obtain the following items. According to the first aspect of the present invention, the temperature detecting means has a configuration in which a plurality of infrared sensor elements are arranged and an imaging lens is provided on the incident side of the plurality of infrared sensor elements, so that the temperature can be detected in a wide range. The size of the temperature detecting means can be reduced while reducing the installation space and the layout design can be improved.Also, the uniformity of the distribution of the measurement points can be improved, and the temperature measurement accuracy can be improved and the control can be improved. Reliability can be improved.

According to the second aspect of the invention, the rotating body is driven to rotate, the detection result from each infrared sensor element of the temperature detection means is measured at each predetermined rotation angle position, and the temperature measurement results at a plurality of measurement points are measured. , The temperature distribution can be detected satisfactorily in almost the entire heating chamber even if the number of infrared sensor elements is small.

According to the third aspect of the present invention, the area index that increases as the distance from the center of the rotating body is set for each measurement point, and the temperature measurement result at each measurement point by the temperature distribution detecting means is used to determine the presence or absence of food. Since the measurement point where the food is present is detected by comparing with the reference temperature for use, and the area of the food is detected by summing the area index for each measurement point, the area of the food can be detected with high accuracy.

According to the fourth aspect of the present invention, the number of times that the temperature measurement result at the measurement point obtained by the temperature distribution detecting means shows the characteristic of rising and falling in the rotating direction of the rotating body or the characteristic of changing to the opposite. , The number of foods can be detected with high accuracy. According to the fifth aspect of the present invention, the operation of the microwave generator is stopped in the required period for detecting the number of foods, so that the food temperature change is small in the required period and the detection accuracy of the number of foods is improved. I do.

According to the invention of claim 6, when the food form detecting means detects that the number of foods is plural, the average temperature of the maximum temperature of each food area is calculated, and according to the average temperature. Since the microwave generator is controlled, a plurality of foods can be heated without excess or shortage. According to the invention of claim 7, since the average temperature of the food is calculated and the microwave generator is controlled according to the average temperature, insufficient heating of the whole food can be prevented.

According to the eighth aspect of the present invention, since the position detecting means for detecting the rotation reference position of the rotating body is provided, the rotation angle position of the rotating body can be accurately detected, and the temperature distribution can be detected from the fixed angular position. The detection by means can be started, and an accurate temperature distribution can be detected. According to the ninth aspect of the present invention, when the temperature detecting means is configured to detect the temperature in the heating chamber through the slit-shaped hole from outside the heating chamber, the temperature detection hole is reduced to perform sufficient temperature detection. And microwave leakage can be prevented.

According to the tenth aspect of the present invention, when the cooking end temperature is set by the cooking end temperature setting means, the end judgment reference temperature is set for each infrared sensor element according to the set cooking end temperature. When one of the plurality of infrared sensor elements reaches the end determination reference temperature, the operation of the microwave generator is stopped, so that overheating and insufficient heating of the food can be prevented.

According to the eleventh aspect of the present invention, when a high-temperature portion is detected in a portion other than the center of the rotating body by the food form detecting means, the temperature rise of the high-temperature portion while the rotating body rotates. The temperature of the high temperature portion and the degree of temperature rise are determined, and the rotation angle position of the rotating body at which the high temperature portion reaches the cooking end temperature set by the cooking end temperature setting means is determined, Since the microwave generator is controlled to stop at the rotation angle position, the food can be cooked even when the temperature detection timing for the high temperature portion can be obtained only once per rotation. The heating can be stopped when the temperature reaches the end temperature, and overheating can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a microwave oven according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional plan view of a microwave oven.

FIG. 3 is a vertical sectional front view of a temperature sensor and a hole portion.

FIG. 4 is a perspective view from below a hole portion.

FIG. 5 is a vertical side view of a temperature sensor.

FIG. 6 is a front view of a temperature sensor.

FIG. 7 is a perspective view of a position detection device.

FIG. 8 is a diagram showing an electric system.

FIG. 9 is a diagram showing a detection field of view of each infrared sensor element.

FIG. 10 is a diagram showing measurement points.

FIG. 11 is a flowchart showing control contents.

FIG. 12 is a flowchart showing the control contents of step V2 in FIG. 11;

FIG. 13 is a diagram showing a temperature change of each infrared sensor element at a rotation angle position a.

FIG. 14 is a view showing an example of a food shape;

FIG. 15 is a diagram showing an area index.

FIG. 16 is a diagram showing the relationship between the detection area and the size of food.

FIG. 17 is a flowchart of control contents showing a second embodiment of the present invention.

FIG. 18 is a flowchart showing the control contents of step X2 in FIG. 17;

FIG. 19 is a diagram showing a state of an average temperature at a rotation angle position in a certain food arrangement state.

FIG. 20 is a diagram showing a state of an average temperature at a rotation angle position in another food arrangement state.

FIG. 21 shows the third embodiment of the present invention, and shows the relationship between the set cooking end temperature and the end judgment reference temperature of each infrared sensor element.

FIG. 22 is a view showing a fourth embodiment of the present invention and showing the position of a high-temperature portion;

FIG. 23 is a diagram showing a temperature change in a high temperature portion.

[Explanation of symbols]

3 is an inner box (box), 4 is a heating chamber, 5 is a motor (driving means), 7 is a rotating body, 8 is a rotating plate, 10 is a magnetron (microwave generator), and 12 is a position detecting device (position detecting device). Means, 16 is a temperature sensor (temperature detecting means), 17 is a hole, 18 is a control circuit (temperature distribution detecting means, food form detecting means, control means), and 19 is an imaging lens.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3L086 AA01 CB05 CB10 CB17 CC12 DA19 DA20 5H323 AA23 BB01 BB11 CA06 CB06 FF01 FF10 GG16 GG30 HH03 JJ07 JJ10 KK05 LL17

Claims (11)

[Claims] 1. A heating chamber for accommodating food, a microwave generator for supplying microwaves to the heating chamber to heat the food, and a plurality of infrared sensor elements arranged and a plurality of infrared sensor elements. Temperature detecting means provided with an imaging lens on the incident side; temperature distribution detecting means for detecting a temperature distribution in the heating chamber based on detection results from the infrared sensor elements of the temperature detecting means; A microwave oven comprising: food form detection means for detecting a food form based on a detection result from a distribution detection means; and control means for performing heating control based on the detection result by the food form detection means. 2. The heating chamber is provided with a rotating body which is rotated by a driving means, and a food is arranged on the rotating body. The plurality of infrared sensor elements of the temperature detecting means include a rotating body. Are arranged substantially linearly so as to have a detection field of view in the radial direction, and the temperature distribution detection means drives the rotating body to rotate, and detects a detection result from each infrared sensor element of the temperature detection means at each predetermined rotation angle position. 2. The microwave oven according to claim 1, wherein the temperature distribution is measured based on a temperature measurement result at each measurement point at each predetermined rotation angle position of each infrared sensor element. 3. The food form detecting means sets an area index that increases with distance from the center of the rotating body for each measuring point, and uses the temperature measurement result at each measuring point by the temperature distribution detecting means for food presence / absence determination. 3. The method according to claim 2, wherein a measuring point at which the food is present is detected by comparing with a reference temperature, and an area of the food is detected by summing an area index for each measuring point. microwave. 4. The number of times that the food form detecting means indicates that the temperature measurement result at the measuring point obtained by the temperature distribution detecting means has a characteristic of rising and falling in the rotation direction of the rotating body or a characteristic of changing to the opposite. The microwave oven according to claim 2, wherein the number of foods is detected based on the number of foods. 5. The microwave oven according to claim 4, wherein the food form detection means stops driving the microwave generator during a required period for detecting the number of foods. 6. The control means calculates an average temperature of the highest temperature of each food region when the food form detection means detects that the number of foods is plural, and generates a microwave according to the average temperature. 5. The microwave oven according to claim 4, wherein the microwave oven is adapted to control the apparatus. 7. The control means calculates an average temperature of the food when the food form detecting means detects that the area of the food is equal to or greater than a predetermined value, and controls the microwave generator in accordance with the average temperature. The microwave oven according to claim 3, wherein the microwave oven is provided. 8. The microwave oven according to claim 2, further comprising position detecting means for detecting a rotation reference position of the rotating body. 9. A heating chamber is formed by a box body, a slit-shaped hole for temperature detection is formed in an upper part of the box body, and a temperature detection corresponding to the hole is formed in an outer upper part of the box body. 3. A method according to claim 1, further comprising the step of:
The microwave oven as described. 10. A cooking end temperature setting means for setting a cooking end temperature, wherein the control means, when the cooking end temperature is set by the cooking end temperature setting means, according to the set cooking end temperature. An end determination reference temperature is set for each infrared sensor element, and when any one of the plurality of infrared sensor elements reaches the end determination reference temperature, driving of the microwave generator is stopped. 3. The microwave oven according to 1 or 2. 11. A cooking end temperature setting means for setting a cooking end temperature, wherein the control means rotates the rotating body when the high temperature portion is detected by a food form detecting means in a portion other than the center of the rotating body. Detecting the degree of temperature rise of the high temperature portion during the heating, and determining, based on the temperature of the high temperature portion and the temperature rise degree, that the high temperature portion reaches the cooking end temperature set by the cooking end temperature setting means. The rotation angle position of the rotating body of
3. The microwave oven according to claim 2, wherein the microwave generator is controlled to stop at the rotation angle position.