Image-Forming Apparatus Controller Scanning Period Adjustment
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Solution Overview
Problem
Existing image-forming apparatuses with scanning lenses lacking F-θ characteristics face challenges in maintaining uniform pixel exposure due to non-uniform scanning speeds, leading to image degradation.
Innovation Solution
An image-forming apparatus with a controller that adjusts scanning periods for pixels at central and non-central regions, ensuring equal light-emitting time lengths while allowing non-constant linear scanning speeds, thereby maintaining consistent exposure across the image area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a scanning lens with F-θ characteristics is used to achieve uniform linear velocity scanning, then the laser spot moves uniformly on the photosensitive member, but the device size and cost increase
Solution Approach 1:
The patent changes the clock frequency parameter dynamically during scanning operations. By adjusting the clock frequency to compensate for non-uniform scanning velocity, the system achieves uniform pixel exposure without requiring an F-θ lens, thus resolving the contradiction between scanning precision and device complexity
Solution Approach 2:
The patent replaces the mechanical optical correction system (F-θ lens) with an electrical control system that adjusts clock frequency. This substitution eliminates the need for complex optical components while achieving the same effect of uniform scanning exposure
2Manufacturing precision
If the clock frequency is changed to correct scanning deviation, then pixel positioning accuracy improves, but exposure amounts at different regions become uneven causing image degradation
Solution Approach 1:
The patent applies different clock frequency adjustments to different scanning regions. By making the light-emitting time period region-specific (central region vs. non-central region), it compensates for both positioning deviation and exposure unevenness simultaneously, resolving the contradiction between precision and reliability
3Device complexity
If a scanning lens without F-θ characteristics is used to reduce size and cost, then device complexity decreases, but the laser spot does not move at uniform speed causing pixel deviation
Solution Approach 1:
The patent replaces the mechanical F-θ lens with an electrical clock frequency adjustment mechanism. This substitution maintains or improves positioning accuracy while eliminating the need for complex optical components, thus resolving the contradiction between device simplicity and scanning precision
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 ensures consistent toner densities across different regions of the image, improving image quality by maintaining exposure amounts uniform, even without F-θ lens correction.
Implementation Method 1
The laser is reflected by a rotating polygon mirror, and reflected laser light is then transmitted through a scanning lens
Implementation Method 2
Transmitted light irradiates a photosensitive drum to expose the photosensitive drum
Data Source
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Figure 3~4
Figure 5(a)
AI summary
The present disclosure provides an image-forming apparatus and a controller. The image-forming apparatus includes a photosensitive member; a scanning unit, configured to perform laser scanning on the photosensitive member at a non-constant linear speed along a main scanning direction to form an electrostatic latent image; and a controller, configured to make a scanning period T1 corresponding to a first pixel at a central region of the photosensitive member to be not equal to a scanning period T2 corresponding to a second pixel at a non-central region of the photosensitive member. The first pixel and the second pixel are each configured with a light-emitting time period and a non-light-emitting time period; and the light-emitting time period satisfies that a light-emitting time length of the light-emitting time period of the first pixel is same as a light-emitting time length of the light-emitting time period of the second pixel.