Quantcast

Variable-impedance unit, microwave device using the unit, and microwave heater

Imported: 23 Feb '17 | Published: 22 Oct '02

Tomotaka Nobue, Akemi Fukumoto, Akira Ahagon, Tomoko Tani, Koji Yoshino

USPTO - Utility Patents

Abstract

A compact and highly controllable impedance-varying-unit, a microwave device using the same unit, and a high-frequency-heating appliance using the same unit are provided. The impedance varying unit includes a rectangular waveguide-section as a main body made of metallic material, an open end of waveguide-section working on microwave in a microwave cavity, a terminal end of waveguide-section closed by metallic material, a rotary movable body made of non-metallic material, and a driver for the movable body. A rotating angle or a position of the movable body is controlled, so that an impedance at the open end is varied and transmission status of microwave is changed, thereby variably controlling a standing wave distribution. Controlling the standing wave distribution allows an object in the cavity to be selectively heated or uniformly heated. Further, the standing wave produced in the microwave cavity is sequentially varied, so that the object can be selectively heated or uniformly heated. The present invention solves the problem of spark production, and provides a compact as well as highly controllable impedance varying unit, a microwave device using the same unit and a high-frequency-heating appliance using the same unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an impedance varying unit in accordance with a first exemplary embodiment of the present invention.

FIG. 2 illustrates microwave transmission in the impedance varying unit shown in FIG.

1.

FIG. 3 shows characteristics of microwave effect to a movable body made of non-metallic material, used in the impedance varying unit of the present invention.

FIG. 4 shows phase characteristics of a voltage reflection coefficient at an open end of a waveguide section in accordance with an exemplary embodiment shown in FIG.

2.

FIG. 5 shows phase characteristics of a voltage reflection coefficient at an open end of the waveguide with respect to a rotating angle of the movable body in accordance with the embodiment shown in FIG.

2.

FIG. 6 shows characteristics of a signal detected by a microwave detector.

FIG. 7 is a cross section of an impedance varying unit in accordance with a second exemplary embodiment of the present invention.

FIG. 8 shows an impedance varying unit in accordance with a third exemplary embodiment of the present invention. FIG. 8A is a cross sectional view thereof, and FIG. 8B shows a transmission mode of a waveguide section viewed from an open end.

FIG. 9 shows an impedance varying unit in accordance with a fourth exemplary embodiment of the present invention. FIG. 9A shows a structure of a first control example, and FIG. 9B shows a structure of a second control example.

FIG. 10 shows a structure of a microwave device in accordance with a fifth exemplary embodiment of the present invention.

FIG. 11 shows characteristics of distribution of electric field produced in a microwave cavity when the impedance varying unit shown in FIG. 10 is controlled. FIG. 11A shows a distribution of electric field when the movable body is supported at 90 degree. FIG. 11B shows a distribution of electric field when the movable body is supported at 0 (zero) degree.

FIG. 12 is a cross section of a microwave device in accordance with a sixth exemplary embodiment of the present invention.

FIG. 13 shows an appearance of a high frequency heating appliance in accordance with a seventh exemplary embodiment of the present invention.

FIG. 14 is a cross section of an essential part of FIG.

13.

FIG. 15 is an enlarged view of a operation panel shown in FIG.

13.

FIG.

16A-FIG. 16D show displays corresponding to respective operations of operation panel shown in FIG.

15.

FIG. 17 is a flowchart illustrating details of control in the high frequency heating appliance shown in FIG.

13.

FIG. 18 shows heat distribution when a pseudo load is heated in the high frequency heating appliance shown in FIG.

13.

FIG. 19 shows details of a first control of the high frequency heating appliance shown in FIG.

13.

FIG. 20 shows details of a second control of the high frequency heating appliance shown in FIG.

13.

FIG. 21 shows details of a third control of the high frequency heating appliance shown in FIG.

13.

FIG. 22 shows details of a fourth control of the high frequency heating appliance shown in FIG.

13.

FIG. 23 shows an appearance of a high frequency heating appliance in accordance with a eighth exemplary embodiment of the present invention.

FIG. 24 is a cross section of an essential part of FIG.

23.

FIG. 25 is an enlarged part of a operation panel shown in FIG.

23.

FIG. 26 is a flowchart illustrating details of control in the high frequency heating appliance shown in FIG.

23.

FIG. 27 shows heat distribution when a pseudo load is heated in the high frequency heating appliance shown in FIG.

23.

FIG. 28 shows characteristics of water load with respect to variable speeds of the impedance varying unit in the high frequency heating appliance shown in FIG.

23.

Claims

1. An impedance varying unit comprising:

2. The impedance varying unit as defined in claim 1, wherein said movable body is driven by varying a space to a terminal end of said waveguide section.

3. The impedance varying unit as defined in claim 1, wherein a phase value of a voltage reflection coefficient at an open end of said waveguide section includes a value of ±180 degrees.

4. The impedance varying unit as defined in claim 1, wherein a phase value of a voltage reflection coefficient at an open end of said waveguide section includes a value of 0 (zero) degree.

5. The impedance varying unit as defined in claim 1, wherein an approx. center value of a variable range of a phase value of a voltage reflection coefficient at an open end of said waveguide section is ±180 degree.

6. The impedance varying unit as defined in claim 1 further comprising a position detector for detecting a position of said movable body.

7. The impedance varying unit as defined in claim 1 further comprising a microwave detector for detecting an intensity of electromagnetic field in said waveguide section.

8. The impedance varying unit as defined in claim 7, wherein one of a rotating angle and a position of said movable body is determined based on a signal from said microwave detector.

9. The impedance varying unit as defined in claim 1 wherein said driver comprises a stepping motor for driving said movable body.

10. The impedance varying unit as defined in claim 1, wherein said terminal end and said open end form approximately 90 degrees.

11. The impedance varying unit as defined in claim 1, wherein a plurality of said movable bodies are rotatably disposed in said waveguide section, and said movable bodies are independently controlled in rotational manner.

12. The impedance varying unit as defined in claim 1, wherein said waveguide section uses TEn0 (n: a positive interger) propagation mode.

13. A microwave device comprising:

14. The microwave device as defined in claim 13, wherein said opening is disposed so that a flow of a high-frequency-current flowing on a metal wall forming said microwave cavity is broken by the microwave fed.

15. A high frequency heating appliance comprising:

16. The high frequency heating appliance as defined in claim 15 further comprising a table on which the object is placed, and a table driver for rotating said table.

17. The high frequency heating appliance as defined in claim 15 or claim 16, wherein said microwave cavity is substantially a rectangle.

18. The high frequency heating appliance as defined in claim 17, wherein a plurality of said openings are disposed so that longitudinal axes of respective said openings run in different directions.

19. The high frequency heating appliance as defined in claim 15 or claim 16, wherein said opening is disposed so that a flow of a high-frequency-current traveling on a metal wall forming said microwave cavity is broken by the microwave fed.

20. The high frequency heating appliance as defined in claim 19, wherein a plurality of said openings are disposed so that longitudinal axes of respective said openings run in different directions.

21. The high frequency heating appliance as defined in claim 15 or claim 16, wherein a plurality of said openings are disposed so that longitudinal axes of respective said openings run in different directions.

22. The high frequency heating appliance as defined in claim 16, wherein said controller controls said impedance varying unit with halting said table driver based on the heating information of the object.

23. The high frequency heating appliance as defined in claim 15 or claim 16, wherein said controller controls a position of said movable body and an impedance variable speed of said impedance varying unit based on the heating information of the object.

24. The high frequency heating appliance as defined in claim 23, wherein the heating information is physical information obtainable from one of said appliance and the object during heating the object.

25. The high frequency heating appliance as defined in claim 15 or claim 16, wherein a user selectively inputs the heating information.

26. The high frequency heating appliance as defined in claim 25, wherein the information selectively input is one of defrost, re-heating, oven-cooking, and keep-warm.

27. The high frequency heating appliance as defined in claim 15 or claim 16, wherein the heating information is physical information obtainable from one of said appliance and the object during heating the object.

28. The high frequency heating appliance as defined in claim 27, wherein the physical information is an intensity signal of electromagnetic field within one of said microwave cavity and said impedance varying unit.

29. The high frequency heating appliance as defined in claim 27, wherein the heating information the user selectively inputs specifies a heating area in said microwave cavity.