Image Forming Apparatus Pixel Distance Correction and Luminance Control
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Solution Overview
Problem
Existing image forming apparatuses without a scanning lens having an fθ characteristic face challenges in maintaining constant pixel distance and exposure quality due to varying scanning speeds, leading to image defects like fogging and uneven charging.
Innovation Solution
An image forming apparatus with a pixel distance correction unit and a control unit that adjusts light emission luminance to ensure latent images are formed at equal intervals and corrects light emission to account for varying scanning speeds, performing weak exposure on non-image parts to maintain appropriate potential and prevent toner adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a scanning lens having an fθ characteristic is used, then constant scanning speed and equal pixel intervals are achieved, but device size increases and manufacturing cost increases
Solution Approach 1:
The patent extracts the fθ characteristic function from the scanning lens and implements it through software processing (pixel distance correction unit) instead. The scanning lens is reduced to a simple imaging lens without the need for complex fθ correction optics, separating the scanning function from the imaging function.
Solution Approach 2:
The patent replaces the optical mechanical system (complex scanning lens with fθ characteristic) with an electronic/software system (pixel distance correction unit that processes image data). This substitution allows pixel interval correction through digital processing rather than optical design.
2Manufacturing precision
If a scanning lens having an fθ characteristic is used, then constant scanning speed and equal pixel intervals are achieved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the fθ characteristic function from the scanning lens and implements it through software processing (pixel distance correction unit) instead. The scanning lens is reduced to a simple imaging lens without the need for complex fθ correction optics, separating the scanning function from the imaging function.
Solution Approach 2:
The patent uses a simple imaging lens without fθ characteristic instead of an expensive scanning lens with fθ characteristic. The cost reduction is achieved by using cheaper optical components and compensating through software processing capabilities that are already present in digital imaging systems.
3Reliability
If weak exposure is performed on non-image parts, then appropriate potential is maintained and toner adhesion is prevented, but additional control complexity is introduced
Solution Approach 1:
The patent applies different exposure strategies to different regions of the photosensitive member. Image parts receive full exposure for latent image formation, while non-image parts receive weak exposure to maintain appropriate potential. This local differentiation prevents fogging without requiring separate hardware systems.
Solution Approach 2:
The patent combines the weak exposure function for non-image parts with the main exposure system controlled by the light source. The same laser light source performs both image exposure and non-image exposure by modulating intensity based on region type, eliminating the need for separate exposure mechanisms.
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 image quality by correcting pixel distances and luminance variations, suppressing image defects and fogging without the need for a scanning lens with an fθ characteristic, thereby achieving miniaturization and cost reduction.
Implementation Method 1
a light source configured to emit laser light
Implementation Method 2
a deflector configured to deflect the laser light
Implementation Method 3
a photosensitive member, irradiated based on image data by a light source configured to emit laser light
Data Source
AI summary
A pixel distance corrector configured to correct a pixel distance in the main scanning direction so that latent images corresponding to each pixel of image data are formed on the surface of the photosensitive member at substantially equal intervals in the main scanning direction. A controller configured to control a light source to emit light with a first light emission luminance with respect to an image part of the photosensitive member, and a second light emission luminance which is lower than the first light emission luminance, with respect to a non-image part of the photosensitive member. The controller is configured to correct light emission luminance so that the second light emission luminance decreases as the scanning speed decreases.