Asymmetric Imaging Optical Element for Compact Optical Scanning
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Solution Overview
Problem
Conventional optical scanning devices struggle to downsize in the main scanning direction while ensuring a sufficient light amount on the scanned surface, as they often require a larger light source unit and cylindrical lens configuration that compromises light intensity.
Innovation Solution
The optical scanning device incorporates a deflector and an imaging optical system with asymmetric imaging optical elements, where the distance from the optical axis is longer at one end than the other, and the thickness is thinner at one end portion compared to the other, allowing for a more compact design without compromising light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the light source unit and cylindrical lens are brought closer to the deflection means to downsize the device, then the device size is reduced, but the F-number in the sub-scanning cross section increases and sufficient light amount cannot be ensured on the scanned surface
Solution Approach 1:
The patent applies asymmetry by configuring the imaging optical element with different distances from the optical axis to the effective end portions in the main scanning direction. Specifically, the distance from the optical axis to one effective end portion is set to be longer than the distance to the other effective end portion, creating an asymmetric optical path that enables downsizing while maintaining light amount
Solution Approach 2:
The patent implements local quality by making the thickness of the imaging optical element vary in the optical axis direction across different effective end portions. The thickness at one effective end portion is made thinner than at the other, allowing optimized light control in different regions of the optical element to simultaneously achieve compactness and sufficient illumination
2Volume of moving object
If the imaging optical element is configured with asymmetric distances from the optical axis to effective end portions, then downsizing in the main scanning direction is achieved, but the optical path configuration becomes more complex
Solution Approach 1:
The patent resolves the complexity issue by integrating the asymmetric configuration directly into the imaging optical element's structure. The asymmetric distances and varying thickness are built into the element itself, eliminating the need for additional complex optical components or arrangements, thus achieving downsizing without proportionally increasing overall system complexity
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 enables downsizing of the optical scanning device in the main scanning direction while maintaining a sufficient light amount on the scanned surface, improving the device's compactness and performance.
Implementation Method 1
an imaging optical system configured to guide the light beam deflected by the deflector, to the scanned surface
Data Source
AI summary
An optical scanning device includes a deflector for deflecting a light beam to optically scan a scanned region on a scanned surface in a main scanning direction, and an imaging optical system for guiding the light beam deflected by the deflector, to the scanned surface. The imaging optical system includes an imaging optical element in which, in the main scanning direction, a distance to an optical axis from one effective end portion through which a light beam that enters one end portion of the scanned region passes is longer than a distance to the optical axis from another effective end portion through which a light beam that enters another end portion of the scanned region passes. In the imaging optical element, a thickness in an optical axis direction of the one effective end portion is thinner than a thickness in the optical axis direction of the other effective end portion.