Light Scanning Device for Non-Coplanar Scanning Lines
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Solution Overview
Problem
Conventional tandem image forming apparatuses are large in size due to the vertical in-line arrangement of photosensitive members and the use of intermediate transfer belts, which complicates size reduction and leads to vibration issues affecting color registration and print quality.
Innovation Solution
The configuration includes a transfer drum as an intermediate transfer member, and light scanning devices with obliquely oriented deflectors and F-theta lenses to form scanning lines in different planes, reducing the overall size and improving color registration by minimizing distances between light beams and optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photosensitive members are arranged in vertical in-line configuration, then the apparatus can process multiple colors, but the overall height and size of the apparatus increases
Solution Approach 1:
The patent transitions from a vertical in-line arrangement to a planar configuration where photosensitive members are arranged side-by-side in a horizontal plane. This dimensional change allows multiple photosensitive members to coexist without increasing apparatus height, as they are positioned at different lateral positions rather than vertical levels.
Solution Approach 2:
The apparatus is divided into multiple independent scanning units, each with its own light scanning device positioned at a different lateral location. Each scanning unit independently processes one color channel, allowing parallel processing without requiring vertical stacking of components.
2Manufacturing precision
If an intermediate transfer belt is used, then color registration is achieved, but vibration during belt circulation causes registration inaccuracies
Solution Approach 1:
The patent removes the intermediate transfer belt from the system entirely. Instead of transferring images through a circulating belt that introduces vibration, the invention uses a transfer drum that rotates in synchronization with the photosensitive members, eliminating the harmful vibration source while maintaining the color registration function.
Solution Approach 2:
A transfer drum serves as the intermediary between photosensitive members and the final transfer medium. The transfer drum rotates in the same direction and at the same speed as the photosensitive members, providing a stable, vibration-free interface for image transfer while maintaining precise color registration.
3Manufacturing precision
If light beams are scanned at oblique angles with F-theta lenses, then scanning lines are formed in different planes, but optical system complexity increases
Solution Approach 1:
The patent employs asymmetric optical configurations where light scanning devices are positioned at different oblique angles relative to the photosensitive members. F-theta lenses are strategically placed to focus scanned lines onto different planes, creating asymmetric spatial separation that prevents interference while maintaining scanning precision.
Solution Approach 2:
Each light scanning device is configured with specific optical properties tailored to its position and function. F-theta lenses are selectively positioned to provide appropriate focal characteristics for each scanning beam, optimizing local scanning quality while maintaining overall system coordination.
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 allows for a compact image forming apparatus with improved color registration accuracy and reduced size, addressing the challenges of size reduction and vibration-induced inaccuracies in conventional systems.
Implementation Method 1
a light deflector to deflect light beams emitted from light sources into different directions
Implementation Method 2
an F-theta lens to focus, on the photosensitive member, the light beam deflected from the light deflector
Data Source
AI summary
An image forming apparatus having improved arrangement of photosensitive members and configuration of a light scanning device to enable size reduction is described. The image forming apparatus includes a plurality of photosensitive members, a light scanning device to irradiate light beams to the plurality of photosensitive members, so as to form electrostatic latent images on the photosensitive members, a plurality of developers to supply a developing agent to the photosensitive members, so as to form visible images on the photosensitive members, and a transfer drum disposed in contact with the photosensitive members and used to transfer the visible images such that the visible images overlap one another. Scanning lines, which are formed on the plurality of photosensitive members, respectively, by the light scanning device, are arranged in at least two different planes.