Laser Exposure Correction for Virtual Latent-Image Density Control
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Solution Overview
Problem
Conventional image forming apparatuses using interleave scanning methods are prone to reciprocal law failure, leading to density unevenness and color shifts due to variations in scanning pitch, especially in regions across scanning, which affects pseudo high-resolution processing in the sub-scanning direction.
Innovation Solution
An image forming apparatus that includes a laser corrector to adjust the density of virtual latent-image lines by correcting PWM DUTY ratios, bias currents, and light amounts of multiple laser beams, determining whether virtual latent-image lines are formed between adjacent real latent-image lines in the sub-scanning direction, and correcting the laser beams accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interleave scanning method is used to achieve pseudo high-resolution in sub-scanning direction, then resolution is improved, but reciprocal law failure causes density unevenness and color shift
Solution Approach 1:
The patent applies local quality by differentiating the treatment of real and virtual latent-image lines. The controller selectively adjusts laser beam parameters (PWM DUTY ratio, bias current, light amount) based on whether each line is real or virtual, and whether it falls in the across-scanning region. This localized adjustment compensates for reciprocal law failure effects specifically where they occur, while maintaining normal processing elsewhere.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting multiple laser beam parameters including PWM DUTY ratio, bias current, and light amount. These parameter modifications are applied selectively to virtual latent-image lines in the across-scanning region to compensate for the reciprocal law failure, thereby maintaining density uniformity while preserving the pseudo high-resolution effect.
2Productivity
If multiple laser beams are used for exposure, then processing speed is improved, but reciprocal law failure causes dot formation to become thicker and denser in across-scanning region
Solution Approach 1:
The patent applies local quality by differentiating the treatment of real and virtual latent-image lines. The controller selectively adjusts laser beam parameters (PWM DUTY ratio, bias current, light amount) based on whether each line is real or virtual, and whether it falls in the across-scanning region. This localized adjustment compensates for reciprocal law failure effects specifically where they occur, while maintaining normal processing elsewhere.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting multiple laser beam parameters including PWM DUTY ratio, bias current, and light amount. These parameter modifications are applied selectively to virtual latent-image lines in the across-scanning region to compensate for the reciprocal law failure, thereby maintaining density uniformity while preserving the pseudo high-resolution effect.
3Manufacturing precision
If light amount is adjusted at real latent-image line position, then toner image development is controlled, but density adjustment at virtual latent-image line position becomes inaccurate
Solution Approach 1:
The patent applies local quality by differentiating the treatment of real and virtual latent-image lines. The controller selectively adjusts laser beam parameters (PWM DUTY ratio, bias current, light amount) based on whether each line is real or virtual, and whether it falls in the across-scanning region. This localized adjustment compensates for reciprocal law failure effects specifically where they occur, while maintaining normal processing elsewhere.
Solution Approach 2:
The patent implements feedback by using determination information about the virtual latent-image line status to adjust laser beam parameters. The controller receives feedback about whether a virtual latent-image line exists between real lines and uses this information to modify exposure parameters accordingly, ensuring accurate density control while maintaining the benefits of interleave scanning.
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 approach reduces the impact of reciprocal law failure, ensuring consistent density and reducing the likelihood of density unevenness and color shifts during pseudo high-resolution processing.
Implementation Method 1
a plurality of laser light-sources that emit a plurality of laser beams
Implementation Method 2
correcting PWM DUTY ratios, bias currents, and light amounts of multiple laser beams
Implementation Method 3
a polygon mirror that deflects the plurality of laser beams by a plurality of mirror surfaces
Implementation Method 4
an exposure section that forms an electrostatic latent image on the photoreceptor in a charged state
Data Source
AI summary
This disclosure provides an image forming apparatus that adjusts density of a virtual latent-image line by causing a laser corrector to correct a plurality of laser beams. The image forming apparatus controls an exposure section and causes a scanning region of a photoreceptor to be irradiated with the plurality of laser beams in a main-scanning direction to form a real latent-image line, determines whether or not a virtual latent-image line is formed between the two real latent-image lines adjacent to each other in a sub-scanning direction, and causes a laser corrector to correct a plurality of laser beams on the basis of the determination result to adjust density of a virtual latent-image line.