Active solid-state devices (e.g. – transistors – solid-state diode – Semiconductor is an oxide of a metal or copper sulfide
Reexamination Certificate
1997-11-26
2001-08-07
Lee, Eddie (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Semiconductor is an oxide of a metal or copper sulfide
C257S728000, C219S704000, C219S709000
Reexamination Certificate
active
06271538
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a high-frequency detecting element and a high-frequency heater using the detecting element.
In a heater using high-frequency waves (e.g., microwaves), an object is heated mainly because water in the object absorbs the high-frequency waves. The object, when it contains enough water, is properly heated, but the heating continues even after water in the object has completely evaporated. The methods discussed below are available to prevent the heating from continuing after completion of water evaporation so that the object is heated only to an appropriate temperature.
The method disclosed in Japanese Published Unexamined Application No. 62-123226 uses a humidity sensor and an alcohol sensor. The humidity sensor and alcohol sensor are disposed in an exhaust duct and are used to sense water vapor and gas produced from an object in a heating chamber and exhausted from the chamber in order to select a particular cooking method.
The method disclosed in Japanese Published Unexamined Application No. 5-172884 uses a microwave sensor and a temperature sensor. A bridge circuit, comprising the microwave sensor and the temperature sensor, is disposed in a heating chamber. The microwave sensor is composed of a thermistor element for sensing the temperature of an electromagnetic-wave absorber as it heats up upon absorbing microwaves, and the temperature sensor is composed of an electromagnetic-wave reflector and a thermistor element. The electromagnetic-wave absorber and the electromagnetic-wave reflector face a heated object and the thermistor elements detect changes in the temperature of the electromagnetic-wave absorber and the electromagnetic-wave reflector during microwave heating.
The method disclosed in Japanese Published Unexamined Application No. 60-170188 uses a thermistor. Water vapor and gas produced from a heated object in a heating chamber are detected with an absolute temperature sensor or a gas sensor to control an increase in heating chamber temperature due to a heater, using the thermistor to stop the heating operation.
However, all of these methods suffer problems. The method disclosed in Japanese Published Unexamined Application No. 62-123226 has a problem of temperature sensor performance deteriorating due to soiling. The method disclosed in Japanese Published Unexamined Application No. 5-172884 has a problem of the thermistor is slow in responding to an increase in the temperature. The method disclosed in Japanese Published Unexamined Application No. 60-170188 has a problem of a reduction in accuracy due to indirect measurement of the temperature of a heated object.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide both a high-frequency detecting element that can detect a temperature increase in an instant due to high-frequency wave absorption and a high-frequency heater using the detecting element.
A first aspect of the present invention provides a high-frequency detecting element comprising semiconducting ceramic having positive resistance-temperature characteristics, i.e., electrical resistance increases with increased temperatures.
A second aspect of the present invention provides a high-frequency detecting element comprising semiconducting ceramic with positive resistance-temperature characteristics, composed mainly of barium titanate.
A third aspect of the present invention provides a high-frequency detecting element comprising semiconducting ceramic with positive resistance-temperature characteristics, on one main surface of which a pair of electrodes are formed.
A fourth aspect of the present invention provides a high-frequency detecting element comprising semiconducting ceramic with positive resistance-temperature characteristics, the ceramic being 4 mm or less in thickness.
A fifth aspect of the present invention provides a high-frequency detecting element comprising semiconducting ceramic with positive resistance-temperature characteristics, the ceramic having a Curie point of 150° or less.
A sixth aspect of the present invention provides a high-frequency heater including a heating chamber, a high-frequency generating means for generating high-frequency waves in the heating chamber, and a high-frequency detecting element detecting the high-frequency waves generated in the heating chamber.
A seventh aspect of the present invention provides a high-frequency heater whose high-frequency detecting element comprises semiconducting ceramic with positive resistance-temperature characteristics.
A eighth aspect of the present invention provides high-frequency heater whose high-frequency detecting element is composed mainly of barium titanate.
A ninth aspect of the present invention provides a high-frequency heater whose high-frequency detecting element comprises a semiconducting ceramic, on one main surface of which a pair of electrodes are formed.
A tenth aspect of the present invention provides a high-frequency heater whose high-frequency detecting element comprises a semiconducting ceramic with positive resistance-temperature characteristics, which ceramic is 4 mm or less thick.
A eleventh aspect of the present invention provides a high-frequency heater whose high-frequency detecting element comprises a semiconducting ceramic with a Curie point of 150° C. or less.
A twelfth aspect of the present invention provides a high-frequency heater wherein a high-frequency detecting element is disposed so that the other main surface of semiconducting ceramic comprising the detecting element, on which surface no electrodes are formed, faces a heating chamber in which high-frequency waves are generated.
A high-frequency detecting element of the present invention can be a semiconducting ceramic with positive resistance-temperature characteristics, composed mainly of barium titanate, which, when the high-frequency detecting element is exposed to high-frequency waves, generates heat and thus heats up the instant it absorbs the waves.
A high-frequency heater of the present invention uses a high-frequency detecting element comprising a semiconducting ceramic with positive resistance-temperature characteristics and composed mainly of barium titanate, the detecting element detecting temperature under the same conditions as an object is heated with high-frequency waves, since the element is placed in a heating chamber containing the object.
REFERENCES:
patent: 3875361 (1975-04-01), Fujui et al.
patent: 3987267 (1976-10-01), Moore
patent: 3997479 (1976-12-01), Shimojo et al.
patent: 4009359 (1977-02-01), Tallmadge et al.
patent: 4101454 (1978-07-01), Kulwicki et al.
patent: 4401885 (1983-08-01), Ishii et al.
patent: 4415789 (1983-11-01), Nobue et al.
patent: 4616289 (1986-10-01), Itakura et al.
patent: 4716279 (1987-12-01), Hori et al.
patent: 4831432 (1989-05-01), Hori et al.
patent: 5017534 (1991-05-01), Chaput et al.
patent: 5084426 (1992-01-01), Iwaya et al.
patent: 5110216 (1992-05-01), Wickersheim et al.
patent: 5171947 (1992-12-01), Kusunoki et al.
patent: 5294577 (1994-03-01), Yamamoto et al.
patent: 5378875 (1995-01-01), Hirama et al.
patent: 5414403 (1995-05-01), Greuter et al.
patent: 0 360 649 (1990-03-01), None
patent: 2 263 173 (1993-07-01), None
patent: 60-170188 (1985-09-01), None
patent: 62-123226 (1987-06-01), None
patent: 5-172884 (1993-07-01), None
Database WPI, Section E1, Week 7549, Derwent Publications Ltd., London, GB; Class T06, AN 75-N0576W & SU-A-455 332 (MORA), Mar. 14, 1975 (English Abstract).
Official Letter from the Taiwan Intellectual Property Office Dated: Jan. 24, 2000.
Niimi Hideaki
Takaoka Yuichi
Burns Doane , Swecker, Mathis LLP
Lee Eddie
Murata Manufacturing Co. Ltd.
Wilson Allan R.
LandOfFree
High-frequency detecting elements and high-frequency heater... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High-frequency detecting elements and high-frequency heater..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High-frequency detecting elements and high-frequency heater... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2500930