JP2001056123A - Open range - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an open range to high-precisely detect the temperature of a food to be cooked by an infrared ray sensor without being influenced by cooling air. SOLUTION: An infrared ray sensor 20 to detect the temperature of a food to be cooked in a cavity 15 is contained in a sensor holder 18 mounted on a sensor mounting part 30 formed with the side wall of the cavity 15 expanded. In the sensor holder 18, an air barrier plate 39 is mounted on the lower side of an infrared ray sensor 20. The air barrier plate 39 prevents cooling air 23 flowing in through a cooling air inlet 18a below the sensor holder 18 from making direct contact with the infrared ray sensor 20, and the temperature of the infrared ray sensor 20 is kept at a constant value without being influenced by the cooling air 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven for cooking food stored in a cavity by heating the food. More specifically, the present invention relates to a microwave oven for detecting the temperature of food in a cavity by an infrared sensor stored in a tube. The present invention relates to a microwave oven that heats and cooks food while detecting it.

[0002]

2. Description of the Related Art Conventionally, an automatic cooking method in a microwave oven of this type includes a method of measuring the weight of a food during cooking with a weight sensor, and controlling a heating output and a heating time based on the weight to cook. Using a gas sensor or humidity sensor to detect the degree of gas emission from the food, controlling the end of cooking based on the degree of gas emission, and directly detecting the temperature of the food using an infrared sensor. There is a method of performing automatic cooking based on the temperature obtained.

Of the conventional methods described above, the method using a weight sensor is often used in the case of thawing, but this method significantly increases the heating output and heating time depending on the weight of the container on which the food is placed. Because of the differences, the result of the cooking will be quite different.

[0004] For this reason, in the case of thawing, the thawing is not sufficiently performed, and the thawing may not be thawed or may be thawed too much, causing the food to boil.

Further, the method of detecting the end of cooking using a gas sensor or a humidity sensor is different from the method of cooking, such as a food with a lot of juice and a food with a little juice, in that the gas emission is considerably different. The degree of completion varies greatly depending on the type of object.

In the method using the infrared sensor, the temperature of the food is directly detected by the infrared sensor, so that the finish of the cooking can be detected relatively accurately. Here, a method of attaching an infrared sensor to a conventional microwave oven using an infrared sensor and a microwave oven will be described with reference to FIGS.

FIGS. 7A and 7B are a side view and a front view, respectively, showing a conventional method of mounting an infrared sensor on a substrate. As shown in FIG. The sensor light receiving portion is mounted on the substrate 2 so as to face upward. A concave mirror 3 is mounted on the substrate 2 so as to cover the upper part of the light receiving portion of the infrared sensor 1. The infrared sensor 1 is connected to a cooking object (not shown) as shown by a dotted line with an arrow in FIG. The infrared light is condensed by the concave mirror 3 and detected by the infrared sensor 1, and the temperature of the food is measured.

[0008] The output of the infrared sensor 1 for detecting the temperature of the food is generally very small and is affected by even a slight noise, and the reliability of the detected temperature data is impaired. The configuration is such that the sensor 1 and the amplifier are mounted on the same substrate, and the substrate 2 is large.

As shown in FIG. 8, the substrate 2 on which the infrared sensor 1 is mounted is attached to a cavity convex portion 5 bulging out from a side wall of a cavity 4 for storing food in a microwave oven. ing. More specifically, an infrared transmission opening 11 is formed in the cavity convex portion 5, and a sensor holder 6 is attached to the infrared transmission opening 11, and the infrared sensor 1 shown in FIG.
Is mounted on the substrate 2. The sensor holder 6 is made of metal, and has the same potential as the cavity 4, so that an infrared sensor, an amplifier, and the like mounted on the substrate 2 provided inside are electrically shielded.

The infrared sensor unit composed of the infrared sensor 1, the substrate 2, and the concave mirror 3 configured as shown in FIG. 7 is disposed in the sensor holder 6 of FIG. A shutter 8 is provided on the front side of the infrared sensor unit, and the shutter 8 blocks dirt on the infrared sensor unit.

As described above, in addition to the provision of the shutter 8 and the motor 7 for the infrared sensor unit,
Since the infrared sensor unit is also provided with the concave mirror 3 and the like, the distance from the wall surface of the cavity of the infrared sensor unit is inevitably increased.
1 becomes larger, thereby increasing microwave leakage from the infrared transmission port 11 and scattering of food due to gas, water vapor, boiling, etc., from the food that has passed through the infrared transmission port 11 during oven cooking. The infrared sensor becomes easily contaminated, and the high-temperature gas from the oven may destroy the infrared sensor. In order to prevent such a problem, the shutter 8 is provided as described above. Is closed.

In the conventional microwave oven thus configured, cooling air from a cooling fan (not shown) flows into the sensor holder 6 from an opening 91 formed on the lower surface of the sensor holder 6 as shown by an arrow A. Thus, the infrared sensor is cooled, but in such a conventional configuration, the infrared sensor is covered with the substrate 2 and the concave mirror 3, so that the cooling air from the cooling fan does not directly hit the infrared sensor.

However, in the conventional configuration described above,
In addition to the fact that the infrared sensor 1 is mounted on the substrate 2 and covered with the concave mirror 3 and has the shutter 8 and the motor 7, the shape of the infrared sensor unit becomes very large, thereby reducing the housing volume of the microwave oven. In addition to the problem that the volume ratio of the microwave oven consisting of the cavity volume is reduced, the external appearance of the microwave oven becomes larger as a whole, and the installation space of the microwave oven becomes larger, as described above, the infrared transmission port 11 becomes larger. Accordingly, microwave leakage from the infrared transmission port 11 increases, which causes a problem that reliability is reduced. However, in order to solve such a problem,
2. Description of the Related Art An infrared sensor has been developed in which an infrared sensor element is housed in a tubular body, a lens is attached to the tip of the tube, and the infrared sensor element is integrally formed to achieve miniaturization and high reliability.

[0014]

As described above, the infrared sensor housed in the tube having the lens attached to the tip is, for example, the infrared sensor 1 in the sensor holder 6 and the substrate 2 as shown in FIG. It is used in place of the concave mirror 3, the shutter 8 and the motor 7, so that miniaturization and high reliability can be achieved. In this case, the infrared sensor detects the temperature of the food in the cavity via the lens at the tip. Therefore, the lens at the front end is disposed to be opposed to and close to the infrared transmission port 11.

In such a configuration, as shown in FIG. 8, the cooling air flowing from the opening 91 formed in the lower portion of the sensor holder 6 passes around the infrared sensor and the front side of the lens at the tip. In the process of flowing into the cavity, the cooling air directly hits the tube of the infrared sensor, which cools the infrared sensor and makes the temperature of the infrared sensor body unstable, and the infrared sensor accurately measures the temperature of the food. There is a problem that it cannot be detected.

The present invention has been made in view of the above,
It is an object of the present invention to provide a microwave oven in which an infrared sensor can accurately detect the temperature of food without being affected by cooling air.

[0017]

According to a first aspect of the present invention, there is provided an infrared sensor for detecting the temperature of a food in a cavity, which is housed in a tube having a lens attached to a tip thereof. And a cooling fan for cooling the heat-generating portion, and in a microwave oven that heats and cooks while detecting the temperature of the food with an infrared sensor, a cooling fan is provided between the cooling fan and the infrared sensor tube. The gist of the invention is to have a wind shielding means for shielding cooling air.

According to the first aspect of the present invention, since the cooling air from the cooling fan is blocked by the wind shielding means and does not directly hit the tube of the infrared sensor except for the lens, the temperature of the infrared sensor body is reduced. The temperature becomes constant, and the infrared sensor can accurately detect the temperature of the food, so that the cooking of the food can be accurately performed.

Further, the present invention according to claim 2 provides the invention according to claim 1.
In the invention described above, the gist is that the wind shield means is a wind shield box mounted on a substrate on which an infrared sensor is mounted so as to cover the infrared sensor.

According to the second aspect of the present invention, since the infrared sensor is covered with a wind shield box configured, for example, as a cap, the infrared sensor can be reduced in size and can be easily assembled.

Further, the present invention according to claim 3 provides the invention according to claim 1.
In the invention described above, the gist is that the wind shielding means is made of metal, and the metal is connected to a housing of a microwave oven and grounded.

According to the third aspect of the present invention, since the wind shield means is made of metal grounded to the housing of the microwave oven, the infrared sensor can be shielded,
The temperature of the cooked food can be accurately detected.

According to a fourth aspect of the present invention, in the first aspect of the invention, the wind-shielding means is made of a resin, a metal for radio wave shielding is provided on a surface of the resin, and the metal is connected to a housing. The gist is that the grounding is performed.

According to the fourth aspect of the present invention, since the wind-shielding means is made of a resin having a surface provided with a radio wave shielding metal, the heat of the oven can be cut off,
The infrared sensor can be shielded, and the temperature of the food can be accurately detected.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a microwave oven according to one embodiment of the present invention. As shown in FIG. 2, the microwave oven shown in FIG. 1 has a cavity 15 in which a turntable 16 on which food is placed is disposed.
7, and an operation panel 28 is provided on one side of the cavity 15. A machine room provided with, for example, a magnetron and a cooling fan is provided behind the operation panel 28. In FIG.
Only the cooling fan provided in the machine room is denoted by reference numeral 1.
7 schematically. Further, although not shown, an excitation port for supplying a microwave output from a magnetron provided in the machine room into the cavity 15 is provided in the cavity 15.
It is formed inside.

In the microwave oven thus configured, in FIG. 1, among the side walls constituting the cavity 15, the side wall 15 between the cavity 15 and the machine room is provided.
The upper part of “a” bulges to form a sensor mounting portion 30, and a metal sensor holder 18 is mounted to the sensor mounting portion 30 via a heat insulating member 47 with a screw 35. An infrared sensor 20 is provided in the sensor holder 18. This infrared sensor 20 is a sensor board 25
, And the sensor substrate 25 is mounted on a spacer 22 fixed to the sensor holder 18 by screws 26.

FIGS. 3A and 3B show the infrared sensor 20.
As shown in FIG. 2, an imaging lens 21 made of silicon or the like is attached to one end, and an infrared sensor 2 is attached to the other end.
0 to the sensor substrate 25.
There are exposed deployments.

More specifically, the infrared sensor 20 is configured as shown in FIG.
As shown in an enlarged manner in (a) and (b) so as to show the internal structure, a plurality of, in this embodiment, eight, infrared detecting elements 51 to 58 made of thermopiles are arranged in a line to constitute a line sensor. ing. In addition, the infrared sensor 20
The entire structure except for the lens 21 and the plurality of terminals 20a is shielded by a can-type metal container 61, thereby forming a tube with the lens 21 attached to the tip. In this case, the metal container 61 includes the infrared detecting element 51-
58 also extends around the front surface of the lens 21 excluding the field of view 58, and the microwave intrusion prevention unit 6 extends around the front surface of the lens 21.
3 is formed to prevent microwaves from entering the infrared sensor 20.

As shown in FIG. 1, the infrared sensor 20 of the tubular body having the lens 21 mounted on the tip thereof has the opening 2 formed in the sensor mounting portion 30 as shown in FIG.
4, and is disposed in the sensor holder 18. A metal wind shield 39 is provided below the infrared sensor 20, and the wind shield 39 is fixed to the sensor holder 18 by screws 37. The sensor holder 18 has an opening at a lower portion of the wind shield plate 39, and is formed with a cooling air inlet 18a into which the cooling air 23 from the cooling fan 17 provided in the machine room flows as shown by an arrow B.

In the microwave oven configured as described above, the user operates the turntable 1 in the cavity 15.
When the food is placed on the tray 6 and then the operation panel 28 is operated, the microwave oven operates to start heating the food, the turntable 16 starts rotating, and the cooling fan 17 also starts operating. When the microwave oven operates in this manner, the infrared detecting elements 51 to 58 arranged in a line in the infrared sensor 20 and forming a line sensor are:
The temperature distribution of the food (not shown) on the turntable 16 is measured in accordance with the rotation of the turntable 16, and the measurement results are sequentially supplied to a control unit (not shown).

During such cooking, the cooling air from the cooling fan 17 cools electrical components such as an inverter provided in the machine room, and a part of the cooling air is used as cooling air 23 as shown in FIG. The cooling air flows into the sensor holder 18 from the cooling air inlet 18a below the sensor holder 18 as shown by the arrow B, hits the wind shield plate 39, and then flows out into the cavity 15 through the opening 24.

As described above, in the flow of the cooling wind, the presence of the wind shield plate 39 prevents the cooling wind from directly hitting the infrared sensor 20. For this reason, the temperature of the infrared sensor 20 is constant without being affected by the cooling air, and the temperature of the food can be accurately detected.

Here, detection of the temperature of the food by the infrared sensor 20 will be described. The infrared sensor 20 is shown in FIG.
As described above, the infrared detecting elements 51 to 58 made of a thermopile are used.
When the temperature of the food is detected in 1-58, the output voltages of the eight infrared detection elements 51-58 are as follows.

V = ν (T _bb ⁴ −T _am ⁴ ) where V is the output voltage, ν is the adaptation coefficient, T _bb is the absolute temperature of the food, and T _am is the absolute temperature of the infrared sensor 20.

The adaptation coefficient ν is represented by the following equation from the black body temperature T _c and the output voltage V _c when the temperature is calibrated.

Ν = V _c / (T _c ⁴ −T _am ⁴ ) Accordingly, the temperature T _{BB of the} food is given by the following equation.

T _BB = (V / ν) ^1/4 + T _am ^{4 As shown in} this equation, the temperature T _{BB of the} food is directly affected by the absolute temperature T _am of the infrared sensor 20. However, in the present embodiment, since the wind shield plate 39 is provided as described above to prevent the cooling air from directly hitting, the temperature of the main body of the infrared sensor 20 becomes constant, and the temperature of the food can be accurately detected. You can.

The absolute temperature of the infrared sensor 20 is detected by a sensor temperature detecting element (not shown) provided in the infrared sensor 20 or on the sensor substrate 25. 51-58 also detects the temperature of the metal container 61, which is the tube constituting the infrared sensor 20, in addition to the infrared light condensed by the lens 21, but the temperature of the tube of the infrared sensor 20 is uniform. Yes, infrared detecting element 51-
If the temperature of the tube detected by 58 and the temperature of the infrared sensor detected by the sensor temperature detection element are the same, the above equation is established, and regardless of the ambient temperature of the infrared sensor 20, the infrared sensor 20 It becomes possible to accurately measure the temperature of an object.

As described above, the infrared sensor 20
Temperature is constant without being affected by cooling air,
In the process of accurately detecting the temperature of the food, the cooling air 23 from the cooling fan 17 flows into the sensor holder 18 from the cooling air inlet 18a as indicated by the arrow B, and is transmitted to the infrared sensor 20 by the wind shield plate 39. Without hitting directly
The cooling air passes through the front side of the lens 21 of the infrared sensor 20 and flows out of the opening 24 into the cavity 15. An air curtain is formed on the front side, whereby the lens 21 of the infrared sensor 20 is
Is prevented from being contaminated, and furthermore, the cooling air flows out into the cavity 15 through the opening 24, so that steam, gas, oil dust, etc. from the food in the cavity 15 passes through the opening 24 and the lens 21. , And the lens 21 of the infrared sensor 20 can be prevented from being soiled.

The sensor holder 18 is made of a metal having good thermal conductivity as described above, and is mounted on the sensor mounting portion 30 with the screw 35, thereby being electrically connected to the sensor mounting portion 30 and grounded. As a result, the infrared sensor 20 is surrounded and electrically shielded by the metal sensor holder 18 and the wind shield plate 39, and can accurately detect the temperature of the food.

In the above embodiment, the infrared sensor 20 is surrounded by the sensor holder 18 and the wind shield plate 39 made of a metal having good thermal conductivity as described above, Although isolated from heat, in such a configuration, the cooling air 23
Hits against the wind shield plate 39, the sensor holder 18 is cooled around the wind shield plate 39, and thereby the temperature of the infrared sensor 20 is prevented from rising. The temperature of the object can be accurately detected.

Next, a microwave oven according to another embodiment of the present invention will be described with reference to FIG. The microwave oven according to the present embodiment shown in FIG. 5 is different from the microwave oven according to the embodiment shown in FIG.
9 is different from the first embodiment in that a sensor holder 19 and a wind shield plate 41 made of resin are used and metal plating is applied to the outside of the sensor holder 19. It is the same, and the same components are denoted by the same reference numerals.

That is, the resin sensor holder 19 is
The sensor holder 1 is attached to the sensor attachment portion 30 with the screws 35 without the heat insulating member 47 therebetween.
9 is directly applied to the sensor mounting portion 30.
And the infrared sensor 20 is electrically shielded, so that the temperature of the food can be accurately detected.

By surrounding the infrared sensor 20 with the resin-made sensor holder 19 and the wind shield plate 41, the infrared sensor 20 can be easily shielded from the heat of the oven.
The temperature becomes constant, and the infrared sensor 20 can accurately detect the temperature of the food.

Further, since the sensor holder 19 is formed of resin, a member for attaching the infrared sensor 20 to the sensor holder 19 can be integrally formed with the sensor holder 19, so that the structure is simplified and the assembling work is performed. Is also simplified.

Next, a microwave oven according to another embodiment of the present invention will be described with reference to FIG. The microwave oven of the embodiment shown in FIG. 6 removes the wind shield plate 39 in the embodiment shown in FIG. 1 and uses a wind shield box 29 instead, and covers the wind shield box 29 on the infrared sensor 20. , So as to surround the periphery of the infrared sensor 20. Other configurations and operations are the same, and the same components are denoted by the same reference numerals.

That is, in the embodiment shown in FIG.
Numeral 9 is slightly larger than the shape of the infrared sensor 20, and after being put on the infrared sensor 20, the base end is fixed to the sensor substrate 25 by the solder portion 33. Then, the solder portion 33 is connected to the cavity 15 and the like via the circuit of the sensor substrate 25 and grounded, thereby electrically shielding the infrared sensor 20 and allowing the infrared sensor 20 to accurately detect the temperature of the food. Like that. An opening 32 is formed at the tip of the wind shield box 29 so as to face the lens 21, and the infrared sensor 20 can detect the temperature of the food in the cavity 15 through the opening 32. ing.

In the microwave oven configured as described above, similarly to the above-described embodiments, the cooling air inlet 18a is provided.
The cooling air 23 flowing in the direction indicated by the arrow B from FIG.
And then flows out into the cavity 15 through the opening 24. In this case, although the cooling air hits the windshield box 29 but does not directly hit the infrared sensor 20, the infrared sensor The temperature of 20 becomes constant,
It is possible to accurately detect the temperature of the food.

In such a flow of cooling air,
When the cooling air passes through the front surface of the lens 21 of the infrared sensor 20, an air curtain is formed on the front surface of the lens 21.
Is prevented from being contaminated, and furthermore, the cooling air flows out into the cavity 15 through the opening 24, so that steam, gas, oil dust, etc. from the food in the cavity 15 passes through the opening 24 and the lens 21. , And the lens 21 of the infrared sensor 20 can be prevented from being soiled.

[0050]

As described above, according to the first aspect of the present invention, the cooling air from the cooling fan is blocked by the wind shielding means and does not directly hit the tube of the infrared sensor except for the lens. In addition, the temperature of the infrared sensor becomes constant, and the infrared sensor can accurately detect the temperature of the food, so that the cooking of the food can be accurately performed.

According to the second aspect of the present invention, since the infrared sensor is covered with a wind shield box configured as, for example, a cap, the infrared sensor can be reduced in size and can be easily assembled.

Further, according to the present invention, since the wind shielding means is made of metal grounded to the housing of the microwave oven, the infrared sensor can be shielded, and the temperature of the food can be reduced. Can be accurately detected.

According to the fourth aspect of the present invention, the wind shielding means is made of a resin having a surface provided with a radio wave shielding metal, and the metal is grounded to the housing of the microwave oven. Can be blocked, and the infrared sensor can be shielded, so that the temperature of the food can be accurately detected. Further, since the wind shielding means is made of resin, it can be integrally formed with the mounting member of the infrared sensor, so that the structure is simplified and the assembling work can be made more efficient.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a microwave oven according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the overall appearance of the microwave oven shown in FIG.

3A and 3B are a front view and a bottom view showing the appearance of an infrared sensor used in the microwave oven shown in FIG.

FIG. 4 is a plan view and a side view showing a more detailed configuration of the infrared sensor shown in FIG. 3;

FIG. 5 is a sectional view showing a microwave oven according to another embodiment of the present invention.

FIG. 6 is a sectional view showing a microwave oven according to another embodiment of the present invention.

7A and 7B are a side view and a front view showing a conventional method of attaching an infrared sensor to a substrate.

8 is a sectional view of a microwave oven using the infrared sensor shown in FIG.

[Explanation of symbols]

 15 Cavity 17 Cooling fan 18, 19 Sensor holder 18a Cooling air inlet 20 Infrared sensor 21 Lens 23 Cooling air 25 Sensor board 29 Windshield box 30 Sensor mounting part 39, 41 Windshield

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hidenori Kako 991 Anada-cho, Seto-shi, Aichi F-term in Aichi Plant, Toshiba Corporation (reference) 3L086 CB17 DA20 DA23

Claims (4)

[Claims] An infrared sensor, which is housed in a tube having a lens attached to a tip and detects the temperature of the food in the cavity, and a cooling fan for cooling a heat generating portion, the temperature of the food being heated. Microwave oven which heats and cooks while detecting with an infrared sensor, characterized in that it has a wind shielding means for shielding cooling air from the cooling fan between the cooling fan and the tube of the infrared sensor. 2. The microwave oven according to claim 1, wherein the wind shield means is a wind shield box mounted on a substrate on which the infrared sensor is mounted so as to cover the infrared sensor. 3. The microwave oven according to claim 1, wherein the wind shielding means is made of metal, and the metal is connected to a housing of the microwave oven and grounded. 4. The oven according to claim 1, wherein the wind shielding means is made of a resin, a metal for radio wave shielding is provided on a surface of the resin, and the metal is connected to a housing and grounded. range.