Optical Scanner Field Lens Reduces Space and Aberration
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Solution Overview
Problem
Conventional optical scanners face challenges in reducing space allocation and improving optical characteristics when scanning light flux onto multiple photoconductors, leading to increased manufacturing costs and deteriorated imaging quality due to asymmetric wave aberration and limited surface tilt correction.
Innovation Solution
An optical scanner design featuring a rotational deflector with inclination angles tailored for each reflecting surface, a pre-deflection optical system that shapes and converges light flux, and a post-deflection optical system with a common optical element to apply power and achieve desired optical characteristics on the photosensitive surface, reducing the number of optical parts and space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polygon mirror with different inclination angles for each reflecting surface is used to scan light beams onto multiple photoconductors, then scanning precision and control simplicity are improved, but the space required for the optical system in the sub-scanning direction is enlarged
Solution Approach 1:
The patent introduces a field lens in the post-deflection optical system that provides surface tilt correction, enabling the use of smaller inclination angles on the polygon mirror surfaces. This effectively transfers the correction function to a different dimension (the post-deflection optical path), allowing the system to achieve the same scanning precision with reduced spatial requirements in the sub-scanning direction.
Solution Approach 2:
The patent changes the optical parameters by introducing a field lens with specific focal length and positioning it at a determined distance from the polygon mirror. This parameter change enables the system to use smaller inclination angles while maintaining scanning precision, thereby reducing the overall space required for the optical system.
2Area of stationary object
If larger inclination angles are applied to reflecting surfaces to reduce space between optical parts, then space allocation is reduced, but asymmetric wave aberration increases and imaging quality deteriorates
Solution Approach 1:
The patent introduces a field lens as an intermediary element in the post-deflection optical system. This field lens acts as a mediator that corrects the surface tilt of light beams reflected from the polygon mirror, allowing the system to use larger inclination angles without suffering from asymmetric wave aberration, thus improving imaging quality while managing space requirements.
3Device complexity
If the post-deflection optical system lacks surface tilt correction function to reduce complexity, then device complexity is reduced, but allowable surface tilt becomes extremely small and manufacturing cost increases
Solution Approach 1:
The patent designs the post-deflection optical system with a field lens that serves multiple functions: it focuses the light beams onto the photoconductors and simultaneously provides surface tilt correction. This multi-functionality allows the system to tolerate larger inclination angles on the polygon mirror without requiring additional correction mechanisms, thereby reducing manufacturing cost while maintaining imaging quality.
4Device complexity
If a common lens is used in the post-deflection optical system to reduce the number of parts, then cost and complexity are reduced, but scan lines become curved and color registration precision deteriorates
Solution Approach 1:
The patent applies local quality by positioning the field lens at a specific location in the post-deflection optical system and designing it with specific optical properties. This localized intervention allows the common lens to maintain its simplicity while the field lens corrects the scan line curvature and ensures accurate color registration, achieving both cost reduction and precision maintenance.
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 reduces space allocation, minimizes asymmetric wave aberration, and enhances imaging quality by allowing smaller inclination angles and integrated optical elements, resulting in lower costs and improved precision for high-speed, high-definition image formation.
Implementation Method 1
a pre-deflection optical system that shapes the light from the light source into a light flux having a predetermined cross-sectional shape and introduces the light flux to the rotational deflector, and also converges the light flux in a sub-scanning direction in the vicinity of the reflecting surfaces
Implementation Method 2
a rotational deflector that reflects and deflects an incident light flux by a plurality of reflecting surfaces arranged corresponding to the plurality of photoconductors in a rotational direction to scan the incident light flux in the main-scanning direction
Implementation Method 3
a post-deflection optical system that introduces the light flux reflected and deflected by each of the plurality of reflecting surfaces in the rotational deflector to the photosensitive surface of the photoconductor corresponding to each of the reflecting surfaces, wherein the post-deflection optical system includes a common (commonly-used) optical element that applies power to a light flux reflected and deflected in the rotational deflector
Data Source
AI summary
A technique capable of achieving reduction in space of allocating an optical system and improvement of an optical characteristic of a scan light in an optical scanner that scans a light flux from a light source on each of a photosensitive surface of a plurality of photoconductors in a main-scanning direction is provided.An optical scanner comprising: a polygon mirror 80; a pre-deflection optical system 7; and a post-deflection optical system A, wherein the post-deflection optical system A includes a common optical element having a smooth surface acting on all the light fluxes reflected and deflected by each of the plurality of reflecting surfaces in the polygon mirror 80, the common optical element that applies power to the light flux reflected and deflected by the polygon mirror 80 and introduced to each of the plurality of photoconductors, so as to make the light flux introduced to the photosensitive surface by the post-deflection optical system A to have a predetermined optical characteristic on the photosensitive surface depending on an incident position of the light flux.