JP5107947B2 - Rotating antenna rotation detector for high frequency cooking device - Google Patents

Description

  The present invention relates to a high frequency for detecting whether or not a rotating antenna as a uniform heating means disposed in a waveguide for guiding a high frequency such as a microwave generated in a high frequency generator to a heating chamber is actually rotating. The present invention relates to a rotation antenna rotation detection device in a heating cooker.

  Conventionally, in a high-frequency heating cooker, microwaves generated from a high-frequency generator such as a magnetron are irradiated into a heating chamber through a waveguide, and a heated object (food or beverage) placed in the heating chamber is microscopic. It is heated and cooked under the irradiation of waves. The microwave irradiated from the waveguide into the heating chamber forms a standing wave because the wall surface of the heating chamber is made of a metal plate. However, if it is left as it is, heating unevenness occurs in the heated product, which is not preferable.

  Thus, in order to eliminate such heating unevenness, a uniform heating mechanism such as a turntable has been conventionally employed. A heated object is placed on a turntable that is rotated in the heating chamber. While the microwave oven is operating, that is, while microwaves are being irradiated, the turntable is rotated together with the heated object placed on it. Thus, even if there is unevenness in the intensity of the microwave depending on the position in the heating chamber, unevenness in heating is prevented from occurring in the heated object.

  In a cooking device that is difficult to adopt a turntable, such as a drawer-type cooking device, a rotating antenna that rotates an antenna that irradiates microwaves from the waveguide into the heating chamber is adopted as a uniform heating mechanism. There is something. The rotating antenna is composed of metal blades, is attached to the tip of a rotating shaft of a motor provided outside the heating chamber, and is disposed inside the waveguide. The rotating antenna has directivity for the irradiation of radio waves, but by rotating it, the microwaves radiated into the heating chamber are scattered so that heating unevenness does not occur in the heated object even if the heated object is stationary. Yes.

  However, since the rotating antenna is provided on the ceiling wall of the heating chamber, during operation of the heating cooker, microwaves are irradiated into the heating chamber, and it is determined whether the door is open and rotating properly. It cannot be confirmed visually. Therefore, for a rotating antenna for microwave disturbance, a small hole (about φ6) is made in the wall of the waveguide to prevent microwaves from leaking, and the detection light and its reflected light are passed through and reflected to the rotating antenna. By detecting the reflected light, it is determined whether or not the rotating antenna is rotating. That is, a photo interrupter is installed outside the space in which the rotating antenna is housed, the detection light is irradiated from the light emitting element of the photo interrupter to the rotating antenna through the light guide hole of the cavity wall surface, and the reflected light from the rotating antenna is reflected. Has been proposed in which the light is reflected from the light guide hole and received by the light-receiving element of the photo interrupter, and the change in the amount of light due to the rotational displacement of the rotating antenna is detected by the photo interrupter.

  As another type of uniform heating mechanism, there is a microwave oven that includes a stirrer that is a rotating body having an irregular outer shape in a microwave irradiation path and stirs an electric field in a heating chamber. In this microwave oven, if the stirrer stops, there is a problem that uniform heating is not possible. However, since the stirrer is placed in a place where it is difficult to touch the user's eyes, the user does not notice the rotation stop and the food is unevenly heated. However, it is not preferable because it may be misunderstood as the original operation of the microwave oven and may continue to be used. Therefore, it has been proposed to stop the microwave oven in response to the stirrer being stopped (Patent Document 1).

  To stop the stirrer, the rotation axis of the stirrer is extended to the top, and the rotation axis is used to rotate the generator provided as a rotor, the light-receiving element provided on the wall of the stirrer cover, and the lighting during operation to illuminate the inside of the heating chamber It is detected by means such as a light receiving element that detects the intensity of light reflected by the stirrer, or an electric field sensor that is provided in an appropriate part of the wall surface of the heating chamber and detects the electric field in the heating chamber.

  As described above, various methods have been proposed as means for detecting the rotation of the rotating antenna or stirrer. However, optical detection means have problems with reliability such as food gas adhesion, dew condensation, and the effects of vapor intrusion, and also require radio wave shielding technology such as prevention of radio wave leakage from the optical path. Low-cost detection means have not been put into practical use. In addition, there has been proposed a microwave oven equipped with an inspection device for inspecting the operating state of a magnetron by detecting a microwave in a waveguide (Patent Document 2).

  As described above, in the uniform heating mechanism that disturbs the radio wave by the rotational displacement of the rotating antenna, it is an important function to detect the presence or absence of the rotational displacement of the rotating antenna and control the heating. In a structure that detects the rotational displacement of the rotating antenna with a photo interrupter using reflected light, the shape of the light guide hole is determined from the viewpoint of prevention of radio wave leakage and prevention of vapor ingress. Is extremely difficult, but rather requires a reduction in diameter and stretching of the drawn portion.

  Unlike an optical pickup such as a CD player having a similar function, the detection light from the photo interrupter is normal irradiation light having a gentle directivity, and the relative position between the photo interrupter and the light guide hole is an assembly point. Therefore, it is extremely difficult to prevent a part of the detection light from the photo interrupter from being irradiated to the inner surface of the light guide hole that is out of the service area, and the periphery and the vicinity of the light guide hole. Have difficulty. A part of the light radiated from outside the area is reflected outside the area, and then goes back and enters the light receiving element to become a noise signal, which raises the noise floor, making it difficult to discriminate regular signals that fluctuate due to the rotational displacement of the antenna. It becomes.

  The above uniform heating mechanism is an indispensable mechanism for a microwave oven and is a design option. The turntable has the best uniform heating performance, but it is easy to clean the bottom of the heating chamber or rectangular. It is evaluated that it does not reach other mechanisms in terms of restrictions on the diagonal size of non-heated objects, and the occupation ratio of the rotating antenna mechanism is increasing as a whole microwave oven.

Japanese Patent Laid-Open No. 06-203951 JP 2001-52851 A

  In a rotating antenna detection device that detects rotational displacement of a rotating antenna that disturbs microwaves for uniform heating of a heated object with a high-frequency heating cooker based on a change in intensity of reflected light from the rotating antenna, the detected light is transmitted to the rotating antenna. There is a problem to be solved in that the reflection of the hole surface, the periphery, and the vicinity surface of the light guide hole introduced into the light source is reduced to prevent the light signal from entering the light receiving element.

  An object of the present invention is to reduce reflection on the hole surface of the light guide hole that introduces detection light into the rotating antenna, the surrounding surface, and the nearby surface, and suppresses the noise signal from being incident on the light receiving element. It is providing the rotation antenna rotation detection apparatus in the high frequency heating cooker which raised the detection accuracy of this rotation.

  In order to solve the above-described problems, a rotating antenna rotation detection device in a high-frequency heating cooker according to the present invention includes a photo interrupter provided outside a waveguide, and is disposed in the waveguide and irradiated into the heating chamber. A rotating antenna that disturbs microwaves, a detection light generated from a light emitting element of the photo interrupter at a wall portion of the waveguide, and a reflected light that is reflected from the rotating antenna and reaches the light receiving element of the photo interrupter A rotating antenna rotation detecting device in a high-frequency cooking device that detects the rotation of the rotating antenna based on a change in intensity of reflected light from the rotating antenna. In this case, incident light is absorbed in a wavelength band including a wavelength that becomes the center of the detection light on the inner surface of the light guide hole, on the periphery of the light guide hole, and on the vicinity thereof. Wherein the coating that is formed.

  The film can be formed by applying a dark paint. The surrounding area is black painted or surface roughened to reduce the reflectivity (Albedo) and suppress the reflected light from the light guide hole and its surroundings, thus reducing the noise floor of the incident light to the rotation detector The detection accuracy of the intensity change of the reflected light can be increased. As a result, the reliability of the rotation antenna rotation detection device can be improved.

Further, the rotation antenna rotation detecting device in the high frequency heating cooker according to the present invention includes a photo interrupter provided outside the waveguide, and a rotation arranged in the waveguide to disturb the microwave irradiated in the heating chamber. A light guide that passes through the antenna and the detection light generated from the light emitting element of the photo interrupter and the reflected light reflected from the rotating antenna and reaching the light receiving element of the photo interrupter at the wall of the waveguide. A light guide hole formed on a path, wherein the light guide hole is a rotation antenna rotation detecting device in a high-frequency heating cooker that detects rotation of the rotation antenna based on a change in intensity of reflected light from the rotation antenna. The inner surface of the hole and the periphery and the vicinity of the light guide hole are formed on a rough surface that irregularly reflects incident light in a wavelength band including the wavelength that becomes the center of the detection light. And wherein the are.
The rough surface can be formed by disposing a plurality of oval concave surfaces having an outer diameter of approximately ¼ of the central wavelength by chemical treatment or mechanical press.

  In the rotation antenna rotation detecting device in this high-frequency cooking device, the waveguide is fitted and connected to the light guide hole on one end side, and the photo interrupter is mounted on the other end side so that the light guide is inside. A light guide case for defining a path is provided, and the light guide case is provided with a reflecting mirror in the middle of the light guide path, and the reflecting mirror is placed at a temperature near the boiling point of water. A heating element to maintain can be provided.

  Since the rotating antenna rotation detection device in the high-frequency heating cooker according to the present invention is configured as described above, the reflected light from the peripheral portion that has conventionally been a noise signal for the light receiving element of the photo interrupter is reduced. The level of the noise signal is lowered, and the reliability of detecting the rotational displacement of the rotating antenna is increased. In addition, depending on the angle, position variation, light emission characteristic variation, etc., when the photo interrupter is mounted, the emitted detection light beam may be deviated or diffused, but the level of the noise signal is reduced. It is possible to improve the reliability of detecting the rotational displacement.

Side surface sectional drawing shown in the state which pulled out the drawer body when the high frequency heating cooker by this invention is made into a drawer type microwave oven. Side surface sectional drawing which shows the drawer type microwave oven shown in FIG. 1 in the accommodation state of the drawer | drawing-out body. Explanatory drawing which showed the outline of the rotation antenna rotation detection apparatus in the high frequency heating cooker by this invention. Explanatory drawing which showed the outline of the rotation antenna rotation detection apparatus which has the bent light guide path | route in the high frequency heating cooker by this invention.

  Hereinafter, with reference to the drawings, an embodiment of a rotating antenna rotation detection device in a high-frequency cooking device according to the present invention will be described. FIG. 1 is a side sectional view showing a state in which a drawer body is pulled out when the high-frequency heating cooker is a drawer-type microwave oven. FIG. 2 is a side sectional view showing the drawer-type microwave oven shown in FIG.

  As shown in FIG.1 and FIG.2, the drawer type microwave oven 1 is the state accommodated in the microwave main body 2 with which the heating chamber 3 by which a microwave is irradiated is provided, and the heating chamber 3 ( A drawer body 4 that can be pulled out from the microwave oven body 2 toward the outside of the microwave oven main body 2 (the state shown in FIG. 1) is provided. The drawer body 4 includes an opening / closing door 5 at the front end thereof, and the opening 6 of the heating chamber 3 can be closed in a state where the drawer body 4 is stored in the microwave oven body 2.

  In the drawer body 4, the front end portions of the side walls 15 and 15 and the bottom wall 17 are attached to the open / close door 5. The upper portion of the drawer body 4 is open, and the object to be cooked can be taken in and out of the drawer body 4 in a state where the drawer body 4 is pulled out from the microwave oven body 2.

On the rear wall 10 of the microwave oven body 2, an electrical component comprising a magnetron 7, a high-voltage transformer (not shown in FIGS. 1 and 2) for supplying power to the magnetron 7, a power supply device including a high-voltage capacitor, and the like. And an air blower that blows and cools these electric components, and further sends a part of the air that has cooled the electric components into the heating chamber 3.
A waveguide 8 that guides the microwave generated by the magnetron 7 from the rear wall 10 to the heating chamber 3 is provided in the ceiling space 20 formed outside the ceiling of the heating chamber 3 and in the microwave oven body 2. A top surface feeding structure 21 including the same is disposed. Although the magnetron 7 is accommodated in the rear wall portion 10, since the rotating antenna 22 that stirs the generated microwave is inserted inside the waveguide 8, the microwave generated by the magnetron 7 is The light is guided and stirred in the waveguide 8 and is uniformly irradiated into the heating chamber 3 from the ceiling wall of the heating chamber 3.

  A motor 23 is disposed in the ceiling space 20 outside the waveguide 8 to drive the rotating antenna 22, and the output shaft 24 of the motor 23 is guided through the wall of the waveguide 8. A rotating antenna 22 is attached to the distal end portion of the output shaft 24 and extends inside the wave tube 8.

  FIG. 3 is an explanatory diagram showing an outline of the rotation detection device for the rotating antenna provided in the waveguide, and shows a part of the waveguide 8 in cross section. A small light guide hole 25 is formed in a part of the waveguide 8 so as to prevent leakage of microwaves, and antenna reflection is provided on the side and the position of the rotating antenna 22 facing the light guide hole 25. Surface 22a is attached.

  The photo interrupter 30 is a well-known element as a sensor for detecting the presence / absence and position of an object with light, and includes a light emitting element 31 for generating detection light and a light receiving element 32 for receiving detection light that interferes with the object. ing. As the light emitting element 31, a light emitting diode is usually used. In order to avoid malfunctions due to ambient light, infrared light emitting diodes are often employed.

  The photo interrupter 30 is mainly divided into two types, a light shielding type (transmission type) and a reflection type, and the light shielding type detects a light entering element and a light receiving element facing each other and an object enters between them to block light. Type. The reflection type is of a type that detects detection light that is reflected by an object and returns, and the photo interrupter 30 used in the embodiment of the present invention is a reflection type as shown in the figure.

  The detection light 33 generated from the light emitting element 31 of the photo interrupter 30 reaches the rotating antenna 22 through the light guide hole 25 formed in the wall portion of the waveguide 8, and is reflected by the antenna reflecting surface 22 a of the rotating antenna 22. The reflected light passes through the light guide hole 25 and reaches the light receiving element 32 of the photo interrupter 30 as reflected light 34. The rotation of the rotating antenna 22 can be detected by calculating the intensity change of the reflected light from the rotating antenna 22.

  As shown in FIG. 3, a coating 37 that absorbs the detection light 33 in the wavelength band is formed on the inner surface 35 of the light guide hole 25, the periphery thereof, and the vicinity surface 36. Since the detection light 33 is preferably infrared rays, the film 37 is preferably formed by applying a dark paint so that infrared rays can be absorbed. Since the film 37 reduces the reflectivity of the peripheral portion where the noise signal was generated, the level of the noise signal received by the light receiving element 32 is lowered, and the reliability of detecting the rotational displacement of the rotating antenna 22 can be improved. it can.

  Instead of the coating 37, the inner surface 35 of the light guide hole 25, the periphery of the light guide hole 25, and the vicinity surface 36 may be formed as a rough surface that irregularly reflects the detection light 33 in its wavelength band. This rough surface can be formed by disposing a plurality of oval concave surfaces having an outer diameter of approximately ¼ of the wavelength that is the center of the wavelength band of the detection light 33 by chemical treatment or mechanical press. . By irregularly reflecting the detection light 33 in the wavelength band, reflected light incident on the light receiving element 32 as a noise signal can be suppressed.

  FIG. 4 is a diagram showing a rotating antenna rotation detection device having a bent light guide path, and the arrangement of each element is not necessarily the same as in FIG. Description is omitted. A light guide case 26 connected to the light guide hole 25 is attached to the waveguide 8 at a fitting portion 26a.

  In the light guide case 26, a light guide path 27 extending from the light guide hole 25 to the photo interrupter 30 mounted on the mounting portion 26b on the other side is defined. In the light guide case 26, a reflecting mirror (reflector) 28 is provided in the middle of the light guide path 27, and the light guide path is refracted substantially at a right angle. A heating element 29 for heating the reflecting mirror 28 is provided on the back side of the reflecting mirror 28. The detection light 33 generated from the light emitting element 31 of the photo interrupter 30 is reflected by the reflecting mirror 28 through the light guide path 27, passes through the light guide hole 25, reaches the rotating antenna 22, and the antenna reflecting surface of the rotating antenna 22. Reflected at 22a. The reflected light 34 follows the reverse path and reaches the light receiving element 32 of the photo interrupter 30. The rotation of the rotating antenna 22 can be detected by calculating the intensity change of the reflected light from the rotating antenna 22.

  The heating element 29 heats the reflecting mirror 28 to a temperature in the vicinity of the boiling point of water to prevent the light guide path function from being deteriorated due to condensation on the reflecting mirror 28. By using an element having a self-temperature control function as the heating element 29, the temperature of the photo interrupter 30 can be controlled.

  For example, by setting the temperature of the heat generating element 29 to 80 ° C. to 90 ° C. close to the boiling point of water, the inside 26 c of the light guide case 26 becomes positive pressure (positive pressure) as compared with the inside of the cavity of the waveguide 8. Intrusion of vapor from the heating chamber 3 to the mounting portion of the photo interrupter 30 through the light guide case 26 can be prevented. Further, since the temperature of the reflecting mirror 28 is maintained at a temperature near the boiling point of water, dew condensation on the surface of the reflecting mirror 28 is prevented, and the reliability of the rotation detecting device of the rotating antenna having the bent light guide path is improved. Can be increased.

  The above-described embodiment is applied to a drawer type microwave oven. However, in a general microwave oven installed on the top of a kitchen counter or kitchen furniture, the same configuration is used for rotation detection of the rotating antenna. It is possible to apply to. Moreover, although the said Example is a microwave oven which irradiates a microwave in a heating chamber from a cooking appliance top surface, also in the structure which irradiates a microwave into a heating chamber from a bottom face, the same structure is detected by rotation detection of a rotating antenna. It is possible to apply to. Furthermore, although the said Example is applied to the microwave oven which has one magnetron, the same structure can be applied to the rotation detection of a rotating antenna also in the microwave oven which has several magnetrons. It is.

DESCRIPTION OF SYMBOLS 1 Drawer type microwave oven 2 Microwave oven main body 2a Operation panel 3 Heating chamber 4 Drawer body 5 Opening / closing door 5a Handle 6 Opening part 7 Magnetron 8 Waveguide 10 Rear wall part 15 Side wall 17 Bottom wall 18, 19 Slide mechanism 18b, 19b Movable Rail 18a, 19a Fixed rail 20 Ceiling space 21 Top feed structure 22 Rotating antenna 22a Antenna reflecting surface 23 Motor 24 Output shaft 25 Light guide hole 26 Light guide case 26a Fitting portion 26b Mounting portion 26c Internal 27 Light guide path 28 Reflection Mirror (reflector) 29 Heat-generating element 30 Photo interrupter 31 Light-emitting element 32 Light-receiving element 33 Detection light 34 Reflected light 35 Hole inner surface 36 Surrounding and adjacent surface 37 Coating

Claims (5)

A photo interrupter provided outside the waveguide;
A rotating antenna for disturbing microwaves disposed in the waveguide and irradiated in the heating chamber;
On the light guide path through which the detection light generated from the light-emitting element of the photo-interrupter and the reflected light reflected from the rotating antenna and reaching the light-receiving element of the photo-interrupter pass in the wall portion of the waveguide A light guide hole formed,
In the rotation antenna rotation detection device in the high-frequency heating cooker that detects the rotation of the rotation antenna based on the intensity change of the reflected light from the rotation antenna,
A high frequency heating cooker characterized in that a coating that absorbs incident light in a wavelength band including a wavelength that is the center of the detection light is formed on the inner surface of the light guide hole, the periphery of the light guide hole, and the vicinity thereof. Device for detecting rotation of a rotating antenna in a container.   2. The rotating antenna rotation detection device for a high-frequency heating cooker according to claim 1, wherein the film is formed by applying a dark paint. A photo interrupter provided outside the waveguide;
A rotating antenna for disturbing microwaves disposed in the waveguide and irradiated in the heating chamber;
On the light guide path passing through the detection light generated from the light emitting element of the photo interrupter and the reflected light reflected from the rotating antenna and reaching the light receiving element of the photo interrupter at the wall portion of the waveguide A light guide hole formed,
In the rotation antenna rotation detection device in the high-frequency heating cooker that detects the rotation of the rotation antenna based on the intensity change of the reflected light from the rotation antenna,
The high-frequency heating characterized in that the inner surface of the light guide hole, the periphery of the light guide hole, and the vicinity of the light guide hole are formed on a rough surface that irregularly reflects incident light in a wavelength band including a wavelength that is the center of the detection light. Rotating antenna rotation detection device in a cooker.   4. The rough surface is formed by disposing a plurality of oval concave surfaces having an outer diameter of approximately ¼ of the central wavelength by chemical treatment or mechanical press. The rotation antenna rotation detection apparatus in the high frequency heating cooking appliance of description.   The waveguide is fitted and connected to the light guide hole on one end side, and the photo interrupter is mounted on the other end side, and a light guide case for defining the light guide path is provided inside. The light guide case is provided with a reflecting mirror in the middle of the light guide path, and the reflecting mirror is provided with a heating element for maintaining the reflecting mirror at a temperature near the boiling point of water. The rotation antenna rotation detection apparatus in the high frequency heating cooking appliance as described in any one of Claims 1-4.

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