Light Scanning Device Dot Displacement Correction

The patent applies preliminary action by forming evaluation charts before actual image formation to detect dot displacement characteristics. The control portion adjusts light emission timing based on pre-detected displacement data, allowing correction before normal operation. This resolves the contradiction by preparing correction data in advance, enabling high-speed multi-beam scanning while maintaining dot position accuracy through pre-calibrated timing adjustments.

The patent applies segmentation by dividing the control task into separate evaluation and correction phases. The control portion segments the light emitters into multiple groups, each with independently controllable emission timing. By segmenting the control process and using evaluation charts to detect displacement patterns, the system manages complexity while maintaining high resolution through precise individual emitter timing control.

The patent applies asymmetry by creating evaluation charts with deliberately asymmetric dot row arrangements. The first and second dot rows are positioned at different locations in the subscanning direction, creating an asymmetric pattern that amplifies detectable density changes when dot displacement occurs. This asymmetric design enhances measurement precision by making displacement effects more pronounced, while the evaluation chart structure remains relatively simple.