US 4,137,441 A · Microwave oven door seal system

Abstract

A microwave oven having a door with a peripheral microwave seal structure which is fabricated from one or more die formed aluminum parts and solid dielectric inserts to form a resonant transmission line structure with peripheral oven wall portions, with transmission of microwave energy in the seal around the periphery of the door prevented by impedance discontinuities, and leakage of microwave energy through the seal is prevented by impedance mismatch or resonant choke action of the seal structure, and the size of a notch in a solid dielectric insert in a quarter wavelength shorted branch line of the seal is selected for different production runs of the oven to compensate for dimensional changes in different die stamped metal parts or assembled door structures due to assembly jig changes, stamping die wear or assembly procedures.

Claims13

Dependent claims

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.

3 more elements

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.

Dependencies are inferred from the claim text.

Microwave oven door seal system

Life of this patent

Microwave oven door seal system

Life of this patent

Abstract

Claims13