Method and apparatus for heating and drying fabrics in a drying chamber having dryness sensing devices
AssigneeMicro Dry, Inc.
InventorsRobert D. Strattan, Mary E. O'Connor, James R. Sorem, Jr.
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Abstract
The invention relates to a microwave heating and drying method and apparatus utilizing a multiplicity of microwave propagating sources positioned about a heating and drying chamber. The microwave energies are optimized to provide a greater uniformity in the heating and drying of articles disposed in the heating and drying chamber, while preventing interference of the wave propagations. The microwave pulses are cross-polarized and time-multiplexed. Also, the focusing and spread angles are controlled. The end point of the drying cycle is sensed to control microwave generation.
Claims37
A method of sensing the end point of a dry condition in a moist fabric disposed in a microwave heating and drying chamber, comprising the steps of:
- (a) substantially continuously measuring relative humidity at an outlet of said heating and drying chamber;
- (b) comparing the relative humidity at said outlet with a relative humidity reading at an inlet of said chamber;
- and
- (c) determining said end point of the dry condition when said outlet relative humidity falls to within a given percentage of said inlet reading.
A method of sensing the end point of a dry condition in moist fabric disposed in a microwave heating and drying chamber, comprising the steps of:
- (a) substantially continuously measuring absolute humidity output of said chamber;
- (b) comparing said absolute humidity output with a chosen baseline reading obtained at a start of the heating and drying of said fabric;
- and
- (c) determining said end point when said output reaches within a given value of said chosen baseline.
A method of sensing the end point of a dry condition in moist fabric disposed in a microwave heating and drying chamber, comprising the steps of:
- (a) substantially continuously measuring anode temperature of at least one magnetron disposed about said chamber during a heating and drying cycle of said moist fabric;
- (b) sensing a sudden or sharp increase in said anode temperature;
- and
- (c) reducing or terminating power to at least said one magnetron in response to said increase of anode temperature in accordance with step (b).
Dependencies are inferred from the claim text.