Optical Scanning Apparatus Reducing Size via Polygon Mirror Angle Arrangement
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Solution Overview
Problem
Conventional image forming apparatuses with optical scanning systems have a large overall size due to the accumulation of angles between beam light rays, leading to increased size and interference between reflective mirrors and beam light rays.
Innovation Solution
The optical scanning apparatus sets the angle between the second and third beam light rays (θ23) as the smallest, with the angle between the first and second (θ12) being larger than θ23 and the angle between the third and fourth (θ34) being larger than θ12, optimizing the incidence angles to minimize the entire incidence angle and prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the reflection position of beam light rays by reflective mirrors is set closer to the rotating polygon mirror, then the angle formed between adjacent beam light rays can be set larger, but the overall size of the image forming apparatus increases and interference between reflective mirrors and beam light rays occurs
Solution Approach 1:
The patent changes the arrangement dimension of reflective mirrors from a planar configuration to a three-dimensional configuration where mirrors are positioned at different distances from the rotating polygon mirror along the optical axis. This dimensional change allows beam light rays to be reflected at different positions, reducing the accumulation of angles between adjacent beams while preventing interference, thereby compacting the overall apparatus size without compromising optical performance
Solution Approach 2:
The patent applies different reflection positions for different beam light rays (first, second, third, and fourth beams) relative to the rotating polygon mirror. Each reflective mirror is positioned at a specific local position along the optical axis, creating local variations in the optical path. This local quality differentiation allows optimization of angle arrangement for each beam independently, reducing overall apparatus size while preventing interference
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 the overall size of the image forming apparatus while preventing interference between reflective mirrors and beam light rays, maintaining effective image formation.
Implementation Method 1
The rotating polygon mirror includes a plurality of reflective surfaces. The incident optical system allows the first to fourth beam light rays emitted from the light source unit to enter the same reflective surface of the rotating polygon mirror, with a different incidence angle. The first to fourth beam light rays having been reflected by the reflective surface of the rotating polygon mirror are aligned in the order of the first beam light ray, the second beam light ray, the third beam light ray, and the fourth beam light ray, in a rotating axial-center direction of the rotating polygon mirror.
Implementation Method 2
The first to fourth reflective mirrors reflect the first to fourth beam light rays having been reflected by the reflective surface, respectively, to guide these light rays to the first to fourth scanned surfaces.
Data Source
AI summary
An angle formed between a first beam light ray D1 and a second beam light ray D2 is θ12, an angle formed between the second beam light ray D2 and a third beam light ray D3 is θ23, and an angle formed between the third beam light ray D3 and a fourth beam light ray D4 is θ34, where the first, second, third, and fourth beam light rays D1, D2, D3, and D4 have been reflected by a reflective surface of a rotating polygon mirror, θ23 is the smallest, of the three angles, that is, θ12, θ23, and θ34.