Microwave oven door seal system

Claim 2

In a microwave oven excited with microwave energy of a predetermined frequency having an oven wall region providing an access aperture closed by a door and having a microwave energy seal for preventing leakage of microwave energy through the space between peripheral regions of said aperture and peripheral regions of said door; said seal having an input transmission line section and a choke section coupled to said input section, said input section comprising conductive portions of said wall oven spaced from conductive portions of said door by a dielectric medium comprising a solid dielectric having a dielectric constant substantially greater than unity and with said choke section comprising conductive portions of said door substantially enclosing a dielectric medium comprising a solid whose dielectric constant is substantially greater than unity; the improvement comprising: said choke section being formed with dimensions which would resonate at a frequency below said predetermined frequency of said oven if said choke were filled with said solid dielectric; a portion of said solid dielectric being omitted in a tuning region adjacent said coupling region to provide an average dielectric constant in said tuning region which is lower than the dielectric constant of the major portions of said choke section dielectric medium; and the size of said omitted dielectric portion being selected to resonate said choke section substantially at said predetermined microwave oven excitation frequency.

Claim 3

The microwave oven in accordance with claim 1 wherein said input section comprises means for inhibiting the propagation of energy at said frequency peripherally around said door.

Claim 4

The microwave oven in accordance with claim 2 wherein said inhibiting means comprises impedance discontinuities in said input section.

Claim 5

The microwave oven in accordance with claim 3 wherein said impedance discontinuities comprise slots in a common wall between said input line and said choke section.

Claim 6

The microwave oven in accordance with claim 1 wherein said choke section has a substantial short circuit at a distance from the region of coupling to said input line which is substantially a quarter wavelength of said frequency and said region of lower dielectric constant is adjacent said coupling region.

Claim 7

In a microwave oven having a cavity whose interior dimensions are greater than a plurality of free space wavelengths at the frequency of the microwave energy supplied to said cavity by a microwave energy generator, a door closing an access aperture to said oven cavity and a door position sensor for controlling said microwave energy generator for deenergizing said generator when said door is opened during operation of said generator, the improvement comprising: a microwave energy seal between said door and cavity wall surrounding said aperture and having means for inhibiting the excitation from said cavity of transmission of microwave energy in said seal at said frequency around the periphery of said door said seal comprising conductive portions of the periphery of said door and conductive portions of a wall region surrounding said aperture separated by a dielectric medium comprising a solid dielectric having a dielectric constant substantially greater than unity to form an input seal section extending between the interior of said oven and a region of coupling to a choke section and to an output transmission line section each coupled to said input section in said coupling region having a dielectric medium comprising a solid whose dielectric constant is substantially greater than unity in a tuning region adjacent said coupling; an average dielectric constant being lower than the dielectric constant of the major portion of said choke section dielectric medium and with said choke section having its effective electrical wavelength selected by selection of a coupling region dielectric constant to reflect a substantial short circuit to the cavity end of said input section when said door is opened to a point beyond which said door position sensor deenergizes said microwave energy generator.

Claim 8

In a microwave oven having a cavity whose interior dimensions are greater than a plurality of free space wavelengths at the frequency of the microwave energy supplied to said cavity by a microwave energy generator, a door closing an access aperture to said oven cavity and a door position sensor for controlling said microwave energy generator for deenergizing said generator when said door is opened during operation of said generator, the improvement comprising: a microwave energy seal between said door and cavity wall surrounding said aperture and having means for inhibiting the excitation from said cavity of transmission of microwave energy in said seal at said frequency around the periphery of said door said seal comprising conductive portions of the periphery of said door and conductive portions of a wall region surrounding said aperture separated by a dielectric medium comprising a solid dielectric having a dielectric constant substantially greater than unity to form an input seal section extending between the interior of said oven and a region of coupling to a choke section and to an output transmission line section each coupled to said input section in said coupling region having a dielectric medium comprising a solid whose dielectric constant is substantially greater than unity in a tuning region adjacent said coupling; an average dielectric constant being lower than the dielectric constant of the major portion of said choke section dielectric medium and with said choke section having its effective electrical wavelength selected by selection of a coupling region dielectric constant to reflect a substantial short circuit to the cavity end of said input section when said door is opened to a point beyond which said door position sensor deenergizes said microwave energy generator.

Claim 9

The microwave oven in accordance with claim 6 wherein said branch section has an effective electrical length of substantially a quarter wavelength of the frequency of energy produced by said microwave generator.

Claim 10

The microwave oven in accordance with claim 6 wherein a solid dielectric cover for a surface of said door is die formed integrally with solid dielectric portions of the input and output sections of said seal.

Claim 11

The microwave oven in accordance with claim 6 wherein said output section contains a microwave energy absorber.

Claim 12

A microwave oven in accordance with claim 6 wherein said output section comprises a solid dielectric and conductive wall regions coupled to reactive impedance load means for reflecting microwave energy back to said input section of said seal.

Claim 15

The method in accordance with claim 11 wherein said input section has a slotted wall.

Claim 16

The method in accordance with claim 12 wherein said slotted wall also forms a wall of said branch transmission line section.