Tandem Image Forming Apparatus Static Remover Light Control
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Solution Overview
Problem
In image forming apparatuses, the difference in electric potential between the image and non-image parts of a photosensitive drum leads to transfer memory and toner scattering, particularly in tandem-type systems where multiple colors are overlapped, due to uneven transfer currents.
Innovation Solution
The apparatus employs a static remover that emits pre-transfer charge-removing light to the photosensitive drum, with the amount of light adjusted based on the position of the image forming units and environmental conditions, to reduce the electric potential difference between the image and non-image parts, thereby controlling transfer currents and preventing toner scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charges are removed from the surface of the photosensitive drum before the primary transfer, then the difference in electric potential between the image part and the non-image part is reduced, but toner on the image part is likely to scatter to the non-image part
Solution Approach 1:
The patent applies different amounts of charge-removing light to different regions of the photosensitive drum. Specifically, the first static remover emits a greater amount of charge-removing light than the second static remover, creating a localized charge removal effect that reduces electric potential difference in specific areas while preserving toner adhesion in other areas. This spatial differentiation of charge removal intensity resolves the contradiction between reducing potential difference and preventing toner scattering.
2Object-generated harmful factors
If the electric potential at the non-image part around the image part is made greater than at the image part to suppress toner scattering, then the difference in potential is comparatively low, but a current flow into the non-image part cannot be prevented, so it is difficult to resolve a transfer memory
Solution Approach 1:
The patent removes charges from the photosensitive drum surface before the primary transfer process begins. By pre-removing charges through the static removers, the electric potential difference between image and non-image parts is reduced before transfer occurs, preventing both toner scattering and transfer memory effects. This preliminary charge removal action addresses both issues simultaneously.
3Object-generated harmful factors
If charges are removed only from the photosensitive drum in black located at the downstream end to prevent toner scattering, then toner scattering is prevented, but a transfer memory occurs due to a difference between transfer current flowing into the image part and transfer current flowing into the non-image part
Solution Approach 1:
The patent divides the charge removal function into multiple static removers positioned at different locations along the photosensitive drum. The first static remover and second static remover are positioned to cover different regions, with the first emitting greater amounts of charge-removing light. This segmentation allows selective charge removal in different areas, preventing both toner scattering and transfer memory by ensuring uniform charge distribution across the entire drum surface.
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 effectively suppresses transfer memory and toner scattering by managing the electric potential difference, ensuring stable and efficient image transfer in tandem-type systems.
Implementation Method 1
The static remover emits charge-removing light to a portion of the circumferential surface
Data Source
AI summary
An image forming apparatus includes a plurality of image forming units, an endless transfer belt, and a plurality of transfer rollers. Each image forming unit includes a photosensitive drum, a charging unit, a developing unit, and a static remover. The static remover emits charge-removing light to the circumferential surface of the photosensitive drum included in the image forming unit before a transfer to the circumferential surface is performed. The amount of pre-transfer charge-removing light emitted to the circumferential surface of a photosensitive drum by one static remover included in the plurality of image forming units is set to a value less than the amount of pre-transfer charge-removing light emitted to the circumferential surface of another photosensitive drum by another static remover located upstream of the one static remover in the movement direction of an intermediate transfer belt.