JP2001050541A - Infrared rays detector and method for correcting its detecting value - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost case to contain an infrared ray detecting means without using a metallic case having high thermal conductivity and to provide a method for more accurately correcting a detecting temperature detected by the infrared ray detecting means. SOLUTION: This detector comprises a heating chamber to contain a food; an infrared ray detecting means mounted to the outside of a heating chamber so as to detect the temperature of a food; and an infrared ray detector case to contain the infrared ray detecting means. The case is an infrared ray detector formed of synthetic resin containing carbon and consists of an amplifying circuit for an output signal from the infrared ray detecting means and a correcting means to correct the detecting value of the infrared ray detecting means. The correcting means performs separately correction of a detecting value due to unevenness in the output signal characteristics of the infrared ray detecting means, and correction of a detecting value due to unevenness of each of circuit elements of which the amplifying circuit consists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detector for detecting the finished cooking condition of a food to be heated in a cooking apparatus such as a microwave oven, and more particularly to a structure and a method of correcting a detected value.

[0002]

2. Description of the Related Art An infrared detecting means such as a pyroelectric infrared sensor or a thermopile infrared sensor is liable to be erroneously detected when receiving noise such as electromagnetic waves. A resin case in which infrared detecting means is accommodated in a resin case in which copper plating is applied has been used.

However, in the case of such a structure, when the temperature in the heating chamber rises with the progress of cooking, the heat of the air in the room is transmitted to the case of the infrared detector and further transmitted to the infrared detecting means from this case. There is a disadvantage that the temperature of the heated object cannot be detected accurately.

Further, the temperature detection value of the infrared detecting means is determined by detecting the same temperature of the object to be heated due to variations in characteristics of the infrared detecting means itself and variations in each circuit element constituting the detection signal amplifier circuit. However, there is a problem that the temperature detection value varies considerably depending on the product (heating cooking device), and the temperature detection value must be corrected for each product.

[0005]

One of the problems to be solved by the present invention is to provide an inexpensive case for housing the infrared detecting means without using a metal case having high thermal conductivity.

Another object is to provide a method for more accurately correcting the temperature detected by the infrared detecting means.

[0007]

Means for Solving the Problems The first invention of the present invention is:
A heating chamber for storing the food, an infrared detector mounted outside the heating chamber for detecting the temperature of the food, and an infrared detector case for housing the infrared detector, the case including carbon This is an infrared detector formed of synthetic resin.

Further, the case may be an infrared detector formed of a synthetic resin containing a metallic fiber instead of carbon.

According to a second aspect of the present invention, there is provided an infrared detector including a heating chamber for storing food, an infrared detector mounted outside the heating chamber for detecting the temperature of the food, and the infrared detector. Means for amplifying the output signal from the means, and correction means for correcting the detection value of the infrared detection means. The correction means corrects the detection value due to variations in the output signal characteristics of the infrared detection means, and corrects the amplification. This is a method for correcting a detection value of an infrared detector, which individually corrects the detection value due to variations in circuit elements constituting a circuit.

In this method, at least one of the corrections of the two detected values is adjusted by a detected temperature corresponding to the output signal value of the infrared detecting means, and the correction amount is adjusted by: The absolute value of the correction amount is adjusted to be smaller as the detected temperature corresponding to the output signal value of the infrared detector becomes higher.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an infrared detector and a detection value correction method according to the present invention will be described in detail with reference to the drawings, taking an infrared detector of a microwave oven as an example.

FIG. 1 is a front view of the microwave oven, and FIG. 2 is an external perspective view of the microwave oven with the upper case removed.

In these figures, reference numeral 1 denotes a key operation unit;
Is an infrared sensor as an infrared detector, 3 is a blower fan, 4 is a turntable on which the object to be heated 6 is placed, 5 is a field of view of the infrared sensor 2, 7 is a heating room, 8 is a magnetron, and 9 is other electric parts. is there.

The infrared sensor 2 includes a case in which 20% carbon is contained in a case made of a synthetic resin, or a case in which iron powder is mixed in a case made of a synthetic resin, in which infrared detecting means (element) is housed. Was. The infrared sensor is provided with a shutter (not shown) for protecting the infrared detecting means when not in use.

The characteristics of the above case, a conventional synthetic resin case, a metal-plated case and a synthetic resin case containing 20% carbon (C20) are compared as shown in FIGS. become. Here, FIG. 3 shows a C20 case (A), a plating case (A), and a resin case (C) when there is no load and the shutter is closed. 4 shows a state in which the shutter is opened, and FIG. 5 shows a state in which two frozen beef croquettes (70 g) are put into the heating chamber 7 as loads and the shutter is closed.

As is apparent from these figures, the case of the C20 case is stable with less wavering of the waveform and less penetration of radio waves into the case than the other two cases. On the other hand, plating cases and resin cases are often shaken,
It can be seen that radio waves are well entering the case.

The reason why the sensor output changes as a whole when the shutter is open compared to when the shutter is closed is because the temperature of the substance (turntable) in the visual field 5 of the sensor 2 has risen. is there.

FIGS. 6A and 6B show the characteristics of a synthetic resin case mixed with iron powder. FIG. 6A shows the shutter closed with no load, FIG. 6A shows the shutter open with no load, and FIG. 6C shows frozen beef. The case where the shutter is closed with two croquettes is shown. Although the iron powder mixed case is slightly blurred compared to the carbon mixed case, it is equivalent to the plated case and can be said to be sufficiently stable compared to the resin case. That is, it is clear that the carbon case and the metal fiber case have performance equal to or higher than that of the expensive plating case.

Next, a method of correcting the detection value by the infrared sensor will be described.

FIG. 7 is a diagram for explaining the concept of the correction method. When the correction amount α is determined from the difference between the infrared sensor detected temperature and the true temperature of the object when the object at a certain temperature X ° C. is shown, α is used as it is in the temperature zone A or lower, and the temperature zone A to In B, a value obtained by multiplying α by 1 / a is used as a correction amount.

As a result, it is possible to reduce the variation in the detected temperature due to the variation of the infrared sensor 2 alone and the variation of the amplifier circuit in any temperature range.

The method of correcting the variation of the infrared sensor 2 alone, that is, the variation of the output signal characteristic is as follows. (1) A certain representative temperature X.degree. C. for performing the correction is determined, and when the temperature of the object at this X.degree. (2) As shown in the circuit configuration diagram (FIG. 10) of the infrared sensor 2, the amplification circuit 15 and the microcomputer 10 at the time of the above correction, X
The infrared sensor 2 detects the temperature of the object 16 having a stable temperature of ° C. as an object. The sensor signal at this time is amplified by the amplifier circuit 15 and input to the input port of the microcomputer 10. (3) Next, with the existing keys of the operation unit 1, special key operations that are not normally used, for example, the [Range] key and the [Start key] in the enlarged front view of the operation unit 1 in FIG. After that, perform operations such as pressing the [decompression key]. (4) By the above operation, the microcomputer 10 executes the output correction program of the sensor 2. That is, the detection target is X ° C.
, The deviation from the current detected temperature is stored in the memory 11 as a correction amount.

The method of correcting variation in circuit elements of the amplifier circuit 15 is as follows. (1) Determine a representative temperature X ° C. for performing the correction (not necessarily the same as X ° C. when the variation of the sensor 2 is corrected). The output voltage of the ideal infrared sensor 2 with respect to the object at X ° C. is set to V0, and the individual amplifier circuits 1
The difference between the temperature detected by the microcomputer 10 when the voltage V0 is input to the block 5 and X ° C. is corrected. (2) As shown in the circuit configuration diagram of the amplifier circuit 15 and the microcomputer 10 at the time of the above correction (FIG. 12), the stabilized power supply 17 of V0
Is input. This voltage V0 is amplified by the amplifier circuit 15 and input to the input port of the microcomputer 10. (3) Next, with the existing keys of the operation unit 1, special key operations that are not normally used, for example, the [Range] key and the [Start key] in the enlarged front view of the operation unit 1 in FIG. 11 are repeatedly input several times. After that, perform operations such as pressing the [Grill key]. (4) By the above operation, the microcomputer 10 causes the amplification circuit 15
Execute the output correction program. That is, it is assumed that the detection target is X ° C., and the deviation from the current detection temperature is stored in the memory 11 as a correction amount.

This makes it possible to suppress variations in the detected temperature due to variations in the sensors 2 and variations in the amplifier circuits.

The above correction amount can be input and recorded differently for the sensor 2 alone and for the amplifier circuit, and the detected temperature is a temperature corrected based on these two correction amounts. Since the detection accuracy increases as the temperature of the object increases, for example, if the correction amount is determined in accordance with a low temperature range, a problem such as excessive correction being performed in a high temperature range occurs.

Therefore, at least one of the two correction amounts is adjusted according to the temperature band to be detected, and the adjustment is performed such that the absolute value of the correction amount decreases as the temperature band increases.

Next, a specific configuration and a specific process for realizing the above-described correction method will be described with reference to a circuit block diagram of FIG. 8 and FIG. A description will be given based on the flowchart of FIG.

As shown in FIG. 8, the circuit configuration includes a key operation unit 1, a microcomputer 10 receiving an output of the infrared sensor 2 at an input port, and a nonvolatile memory 11 for storing the correction amount and the like. Input from the operation unit 1, detection value input from the infrared sensor 2 and the nonvolatile memory 11
Microwave oscillation circuit 12 based on the correction amount input from
The upper heater 13, the lower heater 14, the cooling fan 3, and the turntable 4 are controlled and driven.

As shown in FIG. 9, when the heating is started (S1), the microcomputer 10 first detects the first temperature by the infrared sensor 2 in S2 (t = detected temperature), as shown in FIG. Next, this t is compared with the temperature zone boundary A (t <=
A) If it is equal to or less than A (S3), the corrected detected temperature T is set to T = t−α (S4).

If t is not less than A in S3, S5
Whether t is greater than A and less than or equal to B (A <t <= B)
Is determined. If t is within this range, the corrected detected temperature T is set to T = t−α / a (a is a constant) (S
6).

If t is greater than A and not less than B in S5, the corrected detected temperature T is calculated as T = t−α / b (b
Is set to a constant, a <b) (S7).

When the corrected detected temperature T is determined in this way, the microcomputer 10 determines whether or not this T has reached the finished temperature set by the key operation unit 1 (T> = finished temperature).
Is checked at any time (S8), and the heating is terminated when it reaches (S9).

[0033]

Since the present invention is configured as described above, radio wave noise due to microwaves can be reduced, and errors in the detected temperature due to variations in the infrared detecting means itself and variations in the detection signal amplifier circuit can be accurately corrected. The expected effect can be expected.

[Brief description of the drawings]

FIG. 1 is a front view of a microwave oven provided with the present invention.

FIG. 2 is an external perspective view of the microwave oven of FIG. 1 in a state where an upper case of the main body is removed.

FIG. 3 is a characteristic diagram of a C20 case (A), a plating case (A), and a resin case (C) when there is no load and the shutter is closed.

FIG. 4 is a characteristic diagram of a C20 case (A), a plating case (A), and a resin case (C) when there is no load and the shutter is open.

FIG. 5 is a characteristic diagram of a C20 case (A), a plating case (A), and a resin case (C) when two frozen beef croquettes (70 g) are put into the heating chamber 7 as a load and the shutter is closed.

6 (a) shows a case where the shutter is closed with no load, (a) shows a shutter open with no load, and (c) shows a case where the shutter is closed with two frozen beef croquettes in the case of a synthetic resin case mixed with iron powder. FIG.

FIG. 7 is a diagram illustrating the concept of a method of correcting a detected temperature.

FIG. 8 is a circuit block diagram of a correction method.

FIG. 9 is a flowchart of a correction method.

FIG. 10 is a circuit diagram of a method for correcting variation of an infrared sensor.

FIG. 11 is an enlarged front view of the operation unit.

FIG. 12 is a circuit diagram of an amplifier circuit correction method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Key operation part 2 Infrared sensor 3 Cooling fan 4 Turntable 5 Field of view 6 Heated object 7 Heating room 8 Magnetron 9 Other electrical parts

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Otsuki 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. F-term (reference) 3L086 AA03 AA04 CA11 CB17 CB20 CC07 CC30 DA20 DA21 3L087 AA05 BA06 BB12 BB20 BC06 CA11 CA13 CB02 CC01 DA20 DA21

Claims (5)

[Claims] 1. A heating chamber for storing food, an infrared detector mounted outside the heating chamber for detecting a temperature of the food, and an infrared detector case housing the infrared detector. An infrared detector, wherein the case is formed of a synthetic resin containing carbon. 2. A heating chamber for storing food, an infrared detector mounted outside the heating chamber for detecting the temperature of the food, and an infrared detector case for housing the infrared detector. An infrared detector, wherein the case contains a metal fiber. 3. A heating chamber for accommodating food, an infrared detector having infrared detection means mounted outside the heating chamber for detecting the temperature of the food, and amplification of an output signal from the infrared detection means. A correction circuit for correcting a detection value of the infrared detection means, wherein the correction means corrects the detection value due to a variation in output signal characteristics of the infrared detection means, and each circuit element constituting the amplification circuit. And correcting the detected values individually according to the variation in the detected values of the infrared detector. 4. The method according to claim 3, wherein at least one of the corrections of the two detection values is adjusted by a detection temperature corresponding to an output signal value of the infrared detection means. The detection value correction method of the infrared detector described in the above. 5. The adjustment of the correction amount is performed such that the absolute value of the correction amount decreases as the detected temperature corresponding to the output signal value of the infrared detection means increases. 4. A method for correcting a detection value of an infrared detector according to 4.