Resin-Molded Polygon Mirror Gate Positioning
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Solution Overview
Problem
Conventional resin-molded rotatable polygon mirrors for image forming apparatuses face challenges in achieving high precision due to uneven resin filling, which affects the surface accuracy of reflecting and supported surfaces, leading to decreased performance.
Innovation Solution
A rotatable polygon mirror molded with resin, featuring recess-projection shaped portions positioned on virtual straight lines equidistant from adjacent gate portions, ensuring accurate resin flow and improved surface accuracy by positioning these features downstream of the resin flow to minimize uneven filling and enhance mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If recessed portions or projected portions are provided on the mold to provide recessed portions or projected portions on the surface of the rotatable polygon mirror, then molding information can be provided on the surface, but uneven resin filling occurs due to changes of resin flow during molding, causing surface accuracy to decrease
Solution Approach 1:
The mold design incorporates preliminary features (ridges and grooves) that are formed before resin injection. These pre-formed features guide the resin flow in a controlled manner, allowing the resin to fill the mold cavity evenly while still forming the required recessed and projected portions on the mirror surface. This preliminary structuring prevents uneven resin filling that would otherwise occur with random recess/projection features.
2Productivity
If resin molding is used instead of metal cutting, then machining man-hours are significantly reduced, but achieving high precision surface accuracy becomes difficult due to uneven resin filling
Solution Approach 1:
The patent replaces the mechanical cutting process (metal machining) with a resin injection molding process. Instead of mechanically removing material to achieve the desired surface accuracy, the invention uses a chemical/physical process where resin is injected under controlled conditions and allowed to cure into the precise shape required. The mold features (ridges, grooves, and other geometric elements) are formed directly during molding rather than requiring subsequent mechanical finishing operations.
3Ease of manufacture
If gate portions are provided on the surface of the rotatable polygon mirror, then resin injection during molding is enabled, but the gate portions remain as marks on the surface affecting appearance and precision
Solution Approach 1:
The invention extracts or removes the gate portions from the final mirror surface through deliberate mold design. By positioning gate portions at specific locations and using mold features such as ridges and grooves, the resin flow is controlled to allow gate portions to be either hidden, minimized, or completely removed from the visible surface. This extraction of problematic features ensures that the final mirror surface achieves the required accuracy without visible gate marks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high-precision molding of rotatable polygon mirrors with improved surface accuracy and mechanical strength, reducing machining man-hours and maintaining high performance in optical scanning devices.
Implementation Method 1
uneven resin filling is occurred due to changes of resin flow during molding
Implementation Method 2
a plurality of reflecting surfaces provided in parallel to a rotational axis direction and configured to reflect a light
Data Source
AI summary
A rotatable polygon mirror molded with a resin includes a plurality of reflecting surfaces provided in parallel to a rotational axis direction, a surface perpendicular to the rotational axis direction; a plurality of gate portions provided on the surface and a recess-projection on the surface. The recess-projection has at least one shape of a recess shape recessed in the rotational axis from the and a projection shape projected from the surface as viewed in a direction perpendicular to the rotational axis direction. The recess-projection is provided in a virtual straight line with equal distances from two of the adjacent gate portions with respect to a rotational direction of the rotatable polygon mirror and connecting a rotation center of the rotatable polygon mirror and a boundary of two of the adjacent reflecting surfaces with respect to the rotational direction.