Light Emitting Device Pitch Variation Alignment
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Solution Overview
Problem
In image forming apparatuses using electrophotographic systems, it is challenging to align light-emitting elements on substrates in a main scanning direction without misalignment at switching points, particularly when the pitch of light emitting elements is changed from a first pitch to a second pitch in a central region, leading to issues like black or white streaks in images.
Innovation Solution
A light emitting device comprising a first and second light-emitting-element row, each formed by light-emitting-element array chips with LEDs arranged in a main scanning direction, where the pitch is changed from a first pitch to a second pitch in a central region, ensuring proper alignment and reducing misalignment at switching points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple substrates are arranged in a staggered manner with overlapping portions to form light-emitting element rows, then the light-emitting element head can be formed, but misalignment occurs in the main scanning direction at switching points
Solution Approach 1:
The patent applies local quality by changing the pitch of light emitting elements specifically in the overlapping portion of the substrates. The pitch is set to be different from the non-overlapping portions, creating a local variation that enables precise alignment at switching points. This local pitch modification allows the light emitting elements on different substrates to align accurately when switched, eliminating misalignment issues while maintaining the staggered substrate arrangement for manufacturability.
2Manufacturing precision
If the pitch of light emitting elements is changed from a first pitch to a second pitch in a central region, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the light emitting element arrangement into distinct pitch regions: a first pitch in non-overlapping portions and a second pitch in the overlapping portion. This segmentation allows each region to have optimized pitch characteristics for its specific function, with the transition occurring at defined boundaries. The segmented approach manages complexity by creating clear, manageable pitch zones rather than requiring continuous variable pitch control.
Data Source
AI summary
A light emitting device includes a first light-emitting-element row that includes light emitting elements arranged in a row in a main scanning direction and a second light-emitting-element row that includes light emitting elements arranged in a row in the main scanning direction and that is positioned in such a manner that at least a portion of the second light-emitting-element row overlaps the first light-emitting-element row in a sub scanning direction. The first and second light-emitting-element rows are each formed by arranging light-emitting-element array chips in each of which the light emitting elements are arranged in a row in the main scanning direction. In each of the light-emitting-element array chips, a pitch of the light emitting elements arranged in a row is changed from a first pitch to a second pitch, which is different from the first pitch, in a central region of the row of the light emitting elements.