Variable Transfer Pressure in Tandem Printers to Stop Ghosting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In tandem-type color laser printers, the generation of reverse transfer ghosts occurs when forming monochrome images, as toner images are reversely transferred from the black photoreceptor drum to color photoreceptor drums, leading to image deviation.
Innovation Solution
The implementation of a direct tandem-type image forming apparatus with a conveying belt, photosensitive members, transfer members, and adjustable pushing forces, where the pushing force of the second transfer member is reduced in monochrome mode to prevent reverse transfer of the toner image to the color photoreceptor drums.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second transfer member maintains constant pushing force in both color mode and monochrome mode, then the transfer member can effectively transfer color toner images in color mode, but the toner image is reversely transferred from the sheet to the color photoreceptor drum in monochrome mode causing reverse transfer ghost
Solution Approach 1:
The pushing force of the second transfer member is made variable rather than constant. A pushing force changing unit dynamically adjusts the pushing force based on the printing mode: in color mode, the pushing force is set to a first value sufficient for transferring color toner images; in monochrome mode, the pushing force is reduced to a second value smaller than the first value to prevent reverse transfer of black toner images. This dynamic adjustment resolves the contradiction by adapting the transfer pressure to the specific operational requirements of each mode.
Solution Approach 2:
The physical parameter of pushing force is changed according to the printing mode. The system switches between two distinct pushing force values: a higher first pushing force for color mode and a lower second pushing force for monochrome mode. This parameter change allows the second transfer member to perform effective color toner transfer when needed while preventing harmful reverse transfer when operating in monochrome mode, thus eliminating the reverse transfer ghost problem.
2Object-generated harmful factors
If the pushing force of the second transfer member is reduced in monochrome mode, then reverse transfer ghost is suppressed, but the transfer efficiency of color toner images in color mode may be affected
Solution Approach 1:
The system dynamically adjusts the pushing force based on the detected printing mode. When color mode is detected, the pushing force is maintained at the higher first value to ensure efficient color toner transfer. When monochrome mode is detected, the pushing force is reduced to the lower second value to prevent reverse transfer. This dynamic control ensures that transfer efficiency is optimized for color mode while reverse transfer is suppressed in monochrome mode, resolving the productivity concern.
Solution Approach 2:
The pushing force parameter is selectively changed based on operational mode. The system maintains the higher first pushing force value during color mode operations to preserve transfer efficiency, and only reduces to the second value during monochrome mode when reverse transfer prevention is required. This selective parameter change ensures that productivity is maintained when color transfer is needed while eliminating reverse transfer ghosts when operating in monochrome mode.
Data Source
AI summary
An image forming apparatus includes: a conveying belt; a first photosensitive member; and a second photosensitive member; a first transfer member; a second transfer member; a first pushing member; a second pushing member; and a changing unit, wherein the first photosensitive member is disposed on the upstream side of the second photosensitive member in a conveying direction of the transfer receiving member, and the changing unit changes the pushing force of the second transfer member that is disposed on the downstream side of the first photosensitive member in a conveying direction of the transfer receiving member.