Induction Heating Belt Gap Control for Uniform Temperature

The patent applies local quality by creating different gap conditions at different locations of the fixing belt. The gap between the coil and belt is made smaller at sheet-passing portions to concentrate heating there, and larger at non-sheet-passing portions to reduce heating. This location-specific gap adjustment allows the low heat capacity belt to be heated efficiently where needed while preventing excessive temperature rise where sheets are not present, thus resolving the contradiction between fast response time and uniform temperature control.

The patent applies segmentation by dividing the coil structure into multiple independent coil units arranged along the belt width direction. Each coil unit can be independently controlled to heat specific regions of the belt corresponding to different sheet sizes. This segmentation allows precise temperature control for various recording material sizes while maintaining a relatively simple overall structure, as each coil unit follows the same design pattern and can be manufactured using standardized processes.

The patent applies dynamics by making the gap between the coil and belt adjustable rather than fixed. The gap can be dynamically changed based on sheet size and position requirements. This dynamic adjustment capability allows the system to optimize heating efficiency and temperature uniformity without requiring excessive coil movement, thereby maintaining coil reliability while achieving the desired temperature control through controlled gap variations.