Optical Scanning Apparatus Ghost Light Prevention
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Solution Overview
Problem
Conventional optical scanning apparatuses for image forming devices suffer from the generation of unnecessary light (ghost light) due to reflections from imaging optical elements, which affects the scanning process and image quality.
Innovation Solution
The optical scanning apparatus employs a deflection unit that deflects light fluxes in the main scanning direction using a shared deflection surface, with an incident optical system and imaging optical system having specific curved surfaces to prevent ghost light by ensuring reflected light rays intersect perpendicularly in the sub-scanning cross section, utilizing aspherical surfaces and tilt-decentered output surfaces to block ghost light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single imaging optical system is used to guide light fluxes to multiple photosensitive surfaces, then device complexity is reduced and size is minimized, but ghost light is generated due to reflections from optical surfaces
Solution Approach 1:
A light blocking member is introduced as an intermediary element between the imaging optical system and the photosensitive surfaces. This member selectively blocks ghost light paths while allowing the main light fluxes to pass through, thereby resolving the contradiction between using a simple single imaging optical system and preventing harmful reflections.
Solution Approach 2:
The harmful reflection paths (ghost light) are extracted and blocked separately from the main optical path. By identifying and isolating the specific reflection paths that cause ghost light, the solution removes only the harmful portions while preserving the beneficial simple optical system structure.
2Manufacturing precision
If light blocking members are added to prevent ghost light, then image quality is improved, but device complexity and size increase
Solution Approach 1:
The light blocking member is designed with local quality - it is positioned and shaped to block only specific ghost light paths at specific locations, rather than implementing a complete shielding structure. The blocking surfaces are strategically placed to intercept reflections only where they would cause harm, maintaining simplicity elsewhere in the optical system.
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
This configuration effectively prevents ghost light from entering the imaging optical system, improving image scanning quality and reducing wave-front aberration, while also allowing for a more compact and cost-effective optical system design.
Implementation Method 1
light fluxes that are light-modulated and emitted from a light source (laser or the like) in response to an image signal are periodically deflected by a deflection unit including, for example, a rotational polygon mirror (polygon mirror)
Implementation Method 2
the deflected light fluxes are converged in the form of a spot on a photosensitive surface (surface to be scanned) of a photosensitive member (image bearing member) by an imaging optical system having fθ characteristics
Data Source
AI summary
An optical scanning apparatus includes, a deflection unit configured to deflect first and second light fluxes in a main scanning direction by a same deflection surface, an incident optical system configured to cause the first and second light fluxes to enter the deflection surface, and an imaging optical system configured to converge the first and second light fluxes deflected by the deflection unit to first and second surfaces to be scanned, respectively. The imaging optical system includes first imaging optical element having an output surface including first and second curves that the first and second light fluxes respectively enter, and among light rays included in the first and second light fluxes, the light rays that are reflected by the first and second curves, intersect each other in a sub-scanning cross section perpendicular to the main scanning direction.