Light Scanning Apparatus Beam Misregistration Correction
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Solution Overview
Problem
Conventional light scanning apparatuses using multi-beam light sources suffer from print misregistration and image errors such as moiré and jitter due to manufacturing errors in the scanning lens, which cannot correct beam positions in the main scanning direction, leading to color misregistration in color image forming applications.
Innovation Solution
A light scanning apparatus with a deflection unit that deflects beams from a light source unit with intermittently emitting points, and an imaging optical system that focuses these beams to form spots with controlled time differences, allowing for precise alignment and correction of beam positions in the main scanning direction, thereby minimizing print misregistration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-beam light source is used to improve scanning speed and productivity, then productivity is improved, but print misregistration and image errors occur due to manufacturing errors in the scanning lens
Solution Approach 1:
The invention changes the emission timing parameters of each light-emitting point individually. By adjusting the emission timing of each light-emitting point in the sub-scanning direction based on measured beam interval deviations, the system compensates for focus position changes across the image region, thereby correcting print misregistration while maintaining high scanning speed
Solution Approach 2:
The invention introduces a feedback mechanism where sensors measure the actual beam intervals formed by each light-emitting point, and this measurement information is fed back to control the emission timing of each light-emitting point. This closed-loop control corrects beam position deviations caused by scanning lens manufacturing errors
2Manufacturing precision
If sensors are arranged at two end portions of the image to measure image lengths, then image length correction is achieved, but beam position in the main scanning direction cannot be corrected
Solution Approach 1:
The invention segments the measurement function by assigning dedicated sensors to each light-emitting point in the sub-scanning direction. This allows independent measurement of beam intervals for each light-emitting point, enabling precise detection of beam position deviations in the main scanning direction that cannot be measured by end-position sensors alone
Solution Approach 2:
The invention adds measurement capability in the sub-scanning direction by placing sensors at multiple positions corresponding to each light-emitting point. This dimensional expansion of measurement coverage enables detection of beam interval deviations that affect beam position in the main scanning direction
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 effectively reduces print misregistration and achieves high-resolution imaging by ensuring accurate alignment of spots in the main scanning direction, eliminating color misregistration and improving image quality in color image forming applications.
Implementation Method 1
a light source unit which includes a first light-emitting point which intermittently emits a first beam and a second light-emitting point which intermittently emits a second beam
Implementation Method 2
a deflection unit configured to deflect a first beam and a second beam from the light source unit along a main scanning direction
Implementation Method 3
an imaging optical system configured to focus the first beam and the second beam output from the deflection unit on a surface to be scanned so as to form a plurality of spots
Data Source
AI summary
The object of the present invention is to provide a light scanning apparatus of a simple arrangement which can reduce print misregistration of respective beams in a main scanning direction in an image region even when an inexpensive imaging optical unit which forms a spot image on the image region of a surface to be scanned, and can form a high-resolution image, and an image forming apparatus using the same.