JP2009127922A - Microwave oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave oven capable controlling an output by detecting a spark generated during heating. <P>SOLUTION: Light generated accompanied by the spark is guided to a photo IC diode (illuminance sensor) 10 disposed on a place of a good temperature condition by a light guide path 11, and the light is detected to determine the spark by a microcomputer 15 as a spark determining means and to control the motion of a magnetron 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a microwave oven having a device for detecting sparks generated by microwave power feeding in the presence of metal contact in a heating chamber.

  A microwave oven is a device that absorbs microwaves in food and heats it, but sparks are generated on the metal end face when using metal containers, aluminum foil, and other metal products that come with cooking, or when using metal-decorated tableware. At that time, loud sounds and sparks are generated, which may cause anxiety to the user. In addition, when sparks are generated, if the supply of microwaves is not controlled promptly, the sparks may burn into the oil of the food and produce smoke. In order to avoid such a situation, conventionally, this type of microwave oven has been proposed in which a spark in the heating chamber is detected by an optical sensor attached outside the window (see, for example, Patent Document 1).

FIG. 8 is a cross-sectional view of a conventional microwave oven described in Patent Document 1. In FIG. A magnetron irradiation antenna installed in the microwave oven main body 100 (there is a magnetron generator in FIG. 1 of Patent Document 1, but it seems to be an error in the microwave generator). A microwave is supplied from 101 to the object to be heated 104 in the heating chamber 102 through the reflector 103. An optical sensor 105 is installed so as to monitor a change in the amount of light inside the window 106 in front of the heating chamber 102 through the mesh plate 107.
Japanese Utility Model Publication No. 1-165595

  The configuration in which the conventional light sensor 105 detects the spark in the heating chamber 102 can immediately detect a change in illuminance at the time of the occurrence of the spark, so that it is useful as a detection means, but is erroneously detected by taking in a change in illumination. Even if the light sensor 105 inside the heating chamber 102 has a blind spot (which can be generated by installing an oven pan), it cannot be detected, and even if a position where the blind spot is not found can be found. There is a problem that the ambient temperature is high and the illuminance sensor cannot be attached.

  Therefore, the present invention guides light from the wall of the heating chamber to the illuminance sensor through the light guide path, ensures the degree of freedom of the illuminance sensor mounting position, does not expose the illuminance sensor to external optical noise, and restricts the temperature etc. An object of the present invention is to provide a configuration that reliably detects a spark of a microwave oven by installing an illuminance sensor at an optimal position that is not performed.

  In order to solve the conventional problems, a microwave oven according to the present invention includes a heating chamber for placing food, a magnetron for supplying microwaves for heating the food in the heating chamber, and an illuminance sensor for detecting the brightness in the heating chamber. And a light guide for guiding light from the heating chamber to the illuminance sensor, a signal processing means for detecting spark information in the heating chamber from the output of the illuminance sensor, and a spark determination means.

  As a result, light is guided from the heating chamber to the illuminance sensor through the light guide, ensuring the degree of freedom of the illuminance sensor mounting position, and the illuminance sensor is not exposed to external optical noise and is not limited by temperature or the like. It is possible to install an illuminance sensor.

When a spark occurs, the microwave oven according to the present invention promptly guides the light generated along with the spark to the illuminance sensor through the light guide, detects the occurrence of the spark from the output of the illuminance sensor, and stops or stops the heating output. Therefore, it is possible to remove the user's anxiety and prevent smoke from being generated due to the spark in the heating chamber.

  The first invention includes a heating chamber for placing food, a magnetron for supplying microwaves for heating the food in the heating chamber, an illuminance sensor for detecting the brightness in the heating chamber, and light from the heating chamber to the illuminance sensor. It has a signal processing means for detecting spark information in the heating chamber from the light guide path to be guided and the output of the illuminance sensor, and a spark judgment means. When a spark occurs, the light generated along with the spark is quickly passed through the light guide path. It can be guided to the illuminance sensor, and the occurrence of sparks can be detected from the output of the illuminance sensor, and the heating output can be reduced or stopped, so that the user's anxiety can be removed and smoke from the spark in the heating chamber can be prevented. I can do it.

  The second invention has a plurality of light guide paths for guiding light from the heating chamber to the illuminance sensor, particularly in the first invention, and transmits and processes the light accompanying the spark from the plurality of paths to ensure the spark. This makes it possible to make a determination.

  In the third aspect of the invention, in particular, in the first or second aspect of the invention, the light guide path is constituted by an optical fiber, and is flexible and can be constituted thinly. A narrow gap can be reliably routed to the illuminance sensor for conduction.

  According to a fourth aspect of the invention, in particular, in any one of the first to third aspects of the invention, the side of the light guide that is close to the heating chamber is formed of a glass optical fiber, and the light guide that is not altered by the heat of the heating chamber is provided. It is possible to improve the reliability of the light guide.

  The fifth invention is a heating chamber for placing food, a magnetron for supplying microwaves for heating the food in the heating chamber, an illuminance sensor for detecting the brightness in the heating chamber, and light from the heating chamber to the illuminance sensor. A signal processing unit that installs an illumination source in the vicinity of the guiding light guide and the illuminance sensor, transmits light from the illumination source to the inside of the heating chamber via the light guide, and detects spark information in the heating chamber from the output of the illuminance sensor And a spark determination means, and the spark detection region can be identified.

  The sixth invention includes a heating chamber for placing food, a magnetron for supplying microwaves for heating the food in the heating chamber, an illuminance sensor for detecting the brightness in the heating chamber, and light from the heating chamber to the illuminance sensor. Condensing means between the guiding light guide path, the light guide path and the heating chamber, signal processing means for detecting spark information in the heating chamber from the output of the illuminance sensor, and spark determination means, and generated in the spark in the heating chamber The collected light is efficiently collected and transmitted to the illuminance sensor, which increases the reliability of spark detection.

  According to a seventh aspect of the invention, in the sixth aspect of the invention, the light collecting means is made of glass, and can constitute a light guide that does not deteriorate even by heat of the heating chamber, thereby improving the reliability of the light guide. Is.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a partially cutaway configuration diagram of a microwave oven according to the first embodiment of the present invention.

In FIG. 1, the microwave generated by the magnetron 1 that is a microwave generation source passes through the inside of the waveguide 2 and is supplied from the bottom surface of the heating chamber 3 to the heated object 4 inside the heating chamber 3. A fan 5 that sends cooling air for the magnetron 1, a high-voltage transformer 6, a high-voltage capacitor 7, and a high-voltage diode 8 that are components for supplying high voltage to the magnetron 1 are installed outside the heating chamber 3. In addition, a light guide 11 that transmits optical information inside the heating chamber 3 to a photo IC diode (illuminance sensor) 10 is installed outside the heating chamber 3 through a hole 9 formed in the wall surface of the heating chamber 3.

  The photo IC diode 10 generates a current corresponding to the intensity of light, and the current is taken out as a voltage output of a signal processing means 14 comprising a resistor 12 and a noise removing capacitor 13 mounted in series with the photo IC diode 10. It is.

  FIG. 2 shows the output signal waveform of the signal processing means. 2A is a characteristic diagram showing a waveform without spark, and FIG. 2B is a characteristic diagram showing a waveform with spark. When there is no spark, a voltage output corresponding to the brightness inside the heating chamber 3 is seen, and when there is a spark, a voltage is output following the light emission by the spark.

  The output of the signal processing means 14 is input to an analog / digital conversion input terminal 16 of a microcomputer 15 which is a spark determination means. If it is analyzed that the digitally converted voltage level is greater than a certain level Lth, it is output from the digital output terminal 17 of the microcomputer 15 to open the relay circuit (not shown) and stop the oscillation of the microwave. The spark generated in a state where the end faces of the aluminum foil 18 covered with the object to be heated 4 in the above configuration are in light contact with each other is detected by the photo IC diode 10, and the signal is processed (current-voltage conversion) by the signal processing means 14. The microcomputer 15 serving as a spark determination means determines that a spark has occurred and performs a microwave oscillation stop operation.

  By guiding the light to an arbitrary place through the light guide path 11, it is possible to remove the restriction on the installation place of the photo IC diode 10. By installing the photo IC diode 10 in a place where the temperature is low and guiding the light through the light guide path 11, it is possible to realize a highly reliable spark detection with a high degree of freedom in the place of installation.

  In the present embodiment, the hole 9 is formed in the side wall of the heating chamber 3, but the present invention is not limited to this, and is generated with microwave power feeding in the presence of metal contact in the heating chamber 3. It may be formed on the back wall, ceiling wall, or bottom wall of the heating chamber 3 as long as the spark can be detected.

(Embodiment 2)
FIG. 3 is a partially cutaway configuration diagram of a microwave oven according to the second embodiment of the present invention.

  The difference from the first embodiment is that a path for guiding the light inside the heating chamber 3 from the hole 19 at the back of the heating chamber 3 to the photo IC diode 10 through the light guide path 20 is added. By adding the light guide path 20, the inside of the heating chamber 3 is monitored for sparks from two locations, and the spark monitoring accuracy is improved.

(Embodiment 3)
Next, FIG. 4 shows a sectional view of an optical fiber 21 used as the light guide 11 in the third embodiment of the present invention. The optical fiber 21 has a configuration in which a portion that transmits light, a portion that reflects light, and a clad 23 are formed around the core 22, and the periphery thereof is covered with a protective layer 24. Light accompanying the spark in the heating chamber 3 travels through the core 22 while reaching the photo IC diode 10 while being repeatedly reflected by the clad 21. The optical fiber 21 itself is very flexible and has a diameter of about 1 mm, which is very easy to route. It also has heat resistance,
The installation position of the photo IC diode 10 and the signal processing means 14 can be set to an optimum position at a low temperature.

(Embodiment 4)
Next, FIG. 5 shows a sectional view of an optical fiber 25 used as the light guide 11 in the fourth embodiment of the present invention. The side facing the hole 9 of the heating chamber 3 is an optical fiber 26 made of quartz glass, and the photo IC diode 10 side is an optical fiber 27 made of plastic. Since the heating chamber side 3 may become high temperature by cooking, a glass optical fiber 26 with high heat resistance is used. Since the plastic optical fiber 27 is cheaper than glass, the light guide 11 can be formed at low cost by using glass only in the vicinity of the heating chamber 3 that is affected by heat. Of course, if the price is not taken into consideration, even if the entire light guide 11 is constituted by the silica glass optical fiber 26 having high heat resistance, the performance is not affected.

(Embodiment 5)
Next, FIG. 6 is a partially cutaway configuration diagram of a microwave oven according to the fifth embodiment of the present invention. A white LED (illumination source) 28 is installed in the vicinity of the photo IC diode 10, and when lit, light is guided into the heating chamber 3 through the light guide path 11, and a spark detection range 29 is shown on the bottom surface of the heating chamber 3. . Since the size of the spark detection range 29 depends on the light diffusion characteristics of the light guide path 11, the diameter of the light guide path 11 is increased. It is possible to cover the entire heating chamber 3 by increasing the number, etc., so that it is possible to detect any part of the heating chamber 3 and also when designing a spark detection. This is also an effective means for checking the range.

(Embodiment 6)
Next, FIG. 7 is a partially cutaway configuration diagram of a microwave oven according to the sixth embodiment of the present invention.

  Between the light guide path 11 and the heating chamber 3, a wide-angle lens (light collecting means) 30 is installed so as to look around the heating chamber 3. Installation of the wide-angle lens 30 ensures a wide field of view, and even the spark light generated at the corner of the heating chamber 3 can be reliably guided to the photo IC diode 10 via the light guide path 11, and the spark detection reliability. Improves. Also. A similar condensing function can be achieved with a fish-eye lens whose field of view is 360 degrees instead of the wide-angle lens 30.

  Moreover, since the heating chamber 3 side may become high temperature by cooking, reliability is further improved by using a glass-type condensing means with high heat resistance.

  In addition, since the spark detection is performed with light, the amount of light is attenuated due to contamination of the light guide path 11. For this purpose, a fan may be used to blow wind between the light guide path 11 and the wide-angle lens 30 and to block dirt with an air curtain.

  As described above, in the microwave oven according to the present embodiment, the optical information in the heating chamber 3 is guided to the photo IC diode (illuminance sensor) 10 installed in a place with a good temperature environment by the light guide path 11 to perform the spark detection. Since the magnetron oscillation can be controlled, a safe and highly reliable microwave oven can be realized.

  As described above, the method for detecting sparks by light according to the present invention can be used not only for cooking in a microwave oven, but also for cooking devices in general as an ignition safety device, and can also be applied as a detection sensor for a safety device for preventing abnormal heating. .

The partial notch block diagram of the microwave oven in the 1st Embodiment of this invention (A) Characteristic diagram showing the output signal waveform without spark of the signal processing means in the first embodiment of the present invention, (b) Characteristic diagram showing the waveform with spark of the means. Partial cutaway configuration diagram of a microwave oven in the second embodiment of the present invention Sectional drawing of the optical fiber in the 3rd Embodiment of this invention Sectional drawing of the optical fiber in the 4th Embodiment of this invention Partial cutaway configuration diagram of a microwave oven in the fifth embodiment of the present invention Partial cutaway configuration diagram of a microwave oven in the sixth embodiment of the present invention Cross-sectional view of a conventional microwave oven

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetron 3 Heating chamber 6 High voltage transformer 7 High voltage capacitor 8 High voltage diode 9, 19 hole 10 Photo IC diode (illuminance sensor)
11, 20 Light guide 14 Signal processing means 15 Microcomputer (spark determination means)
21, 25 Optical fiber 28 White LED (illumination source)
30 Wide-angle lens (condensing means)

Claims (7)

A heating chamber for placing food, a magnetron for supplying microwaves for heating the food in the heating chamber, an illuminance sensor for detecting the brightness in the heating chamber, and guiding light from the heating chamber to the illuminance sensor A microwave oven comprising: a light guide; a signal processing unit that detects spark information in the heating chamber from an output of the illuminance sensor; and a spark determination unit. The microwave oven according to claim 1, further comprising a plurality of light guides that guide light from the heating chamber to the illuminance sensor. The microwave oven according to claim 1 or 2, wherein the light guide path is constituted by an optical fiber. The microwave oven according to any one of claims 1 to 3, wherein a side of the light guide adjacent to the heating chamber is configured by a glass optical fiber. A heating chamber for placing food, a magnetron for supplying microwaves for heating the food in the heating chamber, an illuminance sensor for detecting the brightness in the heating chamber, and guiding light from the heating chamber to the illuminance sensor An illumination source is installed in the vicinity of the light guide path and the illuminance sensor, light from the illumination source is transmitted to the inside of the heating chamber via the light guide path, and spark information in the heating chamber is obtained from the output of the illuminance sensor. A microwave oven having signal processing means for detecting and spark determining means. A heating chamber for placing food, a magnetron for supplying microwaves for heating the food in the heating chamber, an illuminance sensor for detecting the brightness in the heating chamber, and guiding light from the heating chamber to the illuminance sensor A microwave oven comprising: a light guide path; a light collecting means between the light guide path and the heating chamber; a signal processing means for detecting spark information in the heating chamber from an output of the illuminance sensor; and a spark determination means. The microwave oven according to claim 6, wherein the light collecting means is made of glass.