# US 12,120,805 B2 · High-frequency heating apparatus

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- Number: US 12,120,805 B2
- Document ID: US12120805B2
- Status: Granted
- Kind: B2
- Application number: 17/420,408
- Filed: 2020-02-03
- Published: 2022-03-17
- Granted: 2024-10-15
- Earliest claimed: 2019-02-13
- Assignees: Panasonic Intellectual Property Management Co., Ltd.
- Applicants: Panasonic Intellectual Property Management Co., Ltd.
- Inventors: Kazuki Maeda; Daisuke Hosokawa; Yoshiharu Oomori
- Web page: https://patentgrep.com/patent/US12120805B2

## CPC

- H05B 6/72: Radiators or antennas
- H05B 6/68: for monitoring or control
- H05B 6/70: Feed lines
- H05B 6/76: Prevention of microwave leakage, e.g. door sealings
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL

## Abstract

A high-frequency heating apparatus includes heating chamber (1), generator (2), radiator (3), and controller (30). Heating chamber (1) has a wall surface including metal, and accommodates object (4) to be heated. Generator (2) generates high-frequency power at any frequency in a band of 2.4 GHz to 2.5 GHz. Radiator (3) includes loop antenna (3) including a plurality of loop portions (3A, 3B), and radiates the high-frequency power generated by generator (2) to heating chamber (1). Controller (30) controls a frequency of the high-frequency power generated by generator (2). According to this aspect, a heating target can be uniformly heated or partially heated without a waveguide for transmitting high-frequency power.

## Claims

### Claim 1

A high-frequency heating apparatus comprising:
a heating chamber having a wall surface including metal and being configured to accommodate a heating target;
a generator configured to generate high-frequency power, and
a radiator having a loop antenna including a plurality of loop portions, and configured to radiate the high-frequency power generated by the generator to the heating chamber; and
a controller configured to control a frequency of the high-frequency power generated by the generator, wherein
the loop portions have different lengths from each other,
each of the plurality of loop portions has a length equal to an integral multiple of half of a wavelength of the high-frequency power,
the controller is configured to cause the generator to output the high-frequency power at a frequency at which resonance is generated in one of the plurality of loop portions, so that the high-frequency power is radiated from the one of the plurality of loop portions, and
the controller is configured to cause the generator to output the high-frequency power at a frequency at which resonance is generated in another of the plurality of loop portions, so that the high-frequency power is radiated from the another of the plurality of loop portions.

### Claim 2 (depends on 1)

The high-frequency heating apparatus according to claim 1, wherein the generator is configured to generate the high-frequency power at any frequency in a band of 2.4 GHz to 2.5 GHz.

### Claim 3 (depends on 1)

The high-frequency heating apparatus according to claim 1, wherein the loop antenna further includes a plurality of transmission lines each extending from a branch point to one of the plurality of loop portions, the branch point being supplied with the high-frequency power, and the plurality of transmission lines being parallel to the wall surface of the heating chamber.

### Claim 4 (depends on 3)

The high-frequency heating apparatus according to claim 3, wherein a length of each of the plurality of transmission lines is ¼ or more and half or less of a wavelength of the high-frequency power.

### Claim 5 (depends on 1)

The high-frequency heating apparatus according to claim 1, further comprising a choke structure body disposed outside the heating chamber above the loop antenna to protrude from the heating chamber, wherein the choke structure body includes a slit provided on a surface that is in contact with the wall surface of the heating chamber, and a cavity extending from the slit.

### Claim 6 (depends on 5)

The high-frequency heating apparatus according to claim 5, wherein the cavity has a depth of approximately ¼ of a wavelength of the high-frequency power.

### Claim 7 (depends on 5)

The high-frequency heating apparatus according to claim 5, wherein the slit has a width of 1 mm or more and 5 mm or less.

### Claim 8 (depends on 5)

The high-frequency heating apparatus according to claim 5, wherein the slit has a length longer than half of a wavelength of the high-frequency power.

### Claim 9 (depends on 5)

The high-frequency heating apparatus according to claim 5, wherein the choke structure body is disposed to intersect with the loop antenna with the wall surface sandwiched between the choke structure body and the loop antenna.