Polygon Mirror Reflection Face Identification in Laser Scanners
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the deformation of latent images due to inaccurate identification of the reflection faces of a polygon mirror leads to image deformation, especially when noise is present in the main-scanning synchronization signal.
Innovation Solution
An information processing apparatus connected to an image forming apparatus identifies the reflection face of a rotary polygon mirror by generating signals with different lengths based on the reflection face, allowing for accurate determination and correction of image data corresponding to each scanning line, thereby ensuring precise image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the image controller identifies a reflection face based on a time interval between adjacent pulses of an input main-scanning synchronization signal, then the face identification can be performed before image formation, but when noise is mixed into the signal, the reflection face cannot be accurately identified
Solution Approach 1:
A light receiver detects the laser beam reflected by the polygon mirror to generate a detection signal, which serves as an intermediary to accurately identify the reflection face. This detection signal acts as a mediator between the polygon mirror rotation and the face identification process, enabling precise identification even when noise is present in the main-scanning synchronization signal.
Solution Approach 2:
The patent replaces reliance on the main-scanning synchronization signal (electrical signal-based method) with a optical detection method using a light receiver to detect the reflected laser beam. This substitution from electrical signal processing to optical detection eliminates the noise interference problem while maintaining accurate timing information for face identification.
2Adaptability or versatility
If the shape of the reflection face differs from one reflection face to another, then the laser beam can be deflected by each reflection face, but the latent image formed on the photosensitive member is deformed
Solution Approach 1:
The patent applies different correction data to image data depending on which reflection face is being used. Each reflection face has its own specific correction parameters stored in memory, allowing the system to compensate for the unique shape characteristics of each reflection face. This local quality approach ensures that image deformation is corrected specifically for each face rather than applying a uniform correction.
Solution Approach 2:
The system uses feedback from the detected reflection face identity to select and apply appropriate correction data. The light receiver detects which reflection face is currently active, this information feeds back to the image controller, which then selects the corresponding correction data from memory and applies it to the image data, creating a closed-loop correction system.
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 solution enables high-accuracy identification of the reflection face, even in the presence of noise, resulting in improved image quality by correcting image data according to each reflection face, thus preventing image deformation.
Implementation Method 1
a rotary polygon mirror, which has a plurality of reflection faces, and which is configured to rotate to deflect the light output from the light source through use of the plurality of reflection faces
Implementation Method 2
a light receiver configured to receive the light deflected by the rotary polygon mirror
Data Source
AI summary
An image forming apparatus includes a laser scanner unit, an engine controller, and an image controller. The laser scanner unit includes a polygon mirror configured to reflect a laser beam to scan a photosensitive drum, and a BD sensor configured to detect the laser beam reflected by the polygon mirror to output a BD signal. The engine controller generates an image formation BD signal synchronized with the BD signal. The image controller identifies a reference reflection face based on the number of times of low levels of an image formation BD signal that has been sampled for a predetermined period from a falling edge of the image formation BD signal. The image controller corrects image data based on the identified reflection face to control image formation processing.