Beam Detection Sensor Terminal Placement for Synchronization Noise Reduction
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Solution Overview
Problem
In electrophotographic image forming apparatuses, existing light scanning units face challenges in accurately detecting horizontal synchronization signals due to noise from refraction and diffusion, leading to misalignments and blurred images, especially when forming high-resolution images.
Innovation Solution
A light scanning unit with a beam detection sensor having at least two output terminals arranged outside the scanning path of the light beam on the light receiving surface, spaced apart by a predetermined distance greater than the beam spot diameter, to reduce noise and improve synchronization signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If output terminals are arranged on the light receiving surface within the scanning path, then the device complexity is reduced, but noise from refraction and diffusion increases
Solution Approach 1:
The patent extracts the harmful output terminals from the scanning path area on the light receiving surface and relocates them to the periphery. This separation removes the source of refraction and diffusion noise while preserving the essential detection function, directly resolving the contradiction between structural simplicity and noise generation.
Solution Approach 2:
The patent introduces a light blocking structure (opening portion) as an intermediary element between the scanning path and the output terminals. This mediator prevents light from reaching the output terminals during scanning, eliminating refraction and diffusion noise while allowing the terminals to remain positioned for signal output.
2Device complexity
If output terminals are placed close to each other, then the device complexity is reduced, but synchronization signal accuracy deteriorates
Solution Approach 1:
The patent applies different spatial arrangements to different regions of the light receiving surface. The scanning path area maintains simplicity for detection, while the periphery area positions output terminals at optimized distances from each other to minimize noise. This localized optimization resolves the contradiction between overall simplicity and signal accuracy.
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 noise in the synchronization signal, enhancing the precision of image formation and preventing misalignments, allowing for clearer and more accurate high-resolution image production.
Implementation Method 1
a beam deflector configured to deflect and to scan the light beam emitted from the light source along a main scanning direction
Implementation Method 2
a scanning optical system configured to receive a first portion of the light beam that is deflected and scanned by the beam deflector and to form an image on a scanning surface with the receive first portion of the light beam
Implementation Method 3
a beam detection sensor configured to receive a second portion of the light beam that is deflected and scanned by the beam deflector to generate a synchronization signal based on the received second portion of the light beam
Data Source
AI summary
Disclosed are a light scanning unit and an electrophotographic image forming apparatus including the light scanning unit. The light scanning unit may include a light source emitting a light beam, a beam deflector that deflects and scans the light beam emitted from the light source in a main scanning direction, a scanning optical system forming an image of a first portion of the light beam that is deflected and scanned by the beam deflector on a scanning surface and a beam detection sensor receiving a second portion of the light beam that is deflected and scanned by the beam deflector for generating a synchronization signal. The beam detection sensor may include a light receiving surface for receiving the second portion of the light beam, and at least two output terminals that are arranged outside an area of the light receiving surface within which the incident second portion of the light beam is confined.