Image Forming Apparatus Transfer Memory Prevention
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Solution Overview
Problem
Image forming apparatuses using a DC charging method experience transfer memory due to uneven surface potential of photosensitive drums, leading to variations in image density, especially when a single power source applies bias voltage to multiple primary transfer rollers.
Innovation Solution
The apparatus includes multiple photosensitive drums, static eliminators, transfer rollers, and load resistors, where static eliminators downstream of photosensitive drums perform static elimination, and load resistors are connected in parallel and series between the power source and transfer rollers to equalize electric currents, preventing transfer memory without requiring multiple power sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single power source applies bias voltage to multiple primary transfer rollers, then device complexity is reduced, but transfer memory occurs due to unequal electric currents
Solution Approach 1:
The patent introduces load resistors with different resistance values for different transfer rollers. Specifically, the load resistor connected to the most upstream primary transfer roller has a larger resistance value than those connected to other primary transfer rollers. This local differentiation in resistance values compensates for the potential difference in surface potentials of photosensitive drums, ensuring that electric currents flowing to each transfer roller are substantially equal, thereby preventing transfer memory while maintaining a single power source configuration.
2Device complexity
If static elimination is not performed on the most upstream photosensitive drum, then device complexity is reduced, but surface potential becomes higher causing transfer memory
Solution Approach 1:
The patent positions a specific static eliminator between the most upstream photosensitive drum and the second upstream photosensitive drum to perform static elimination on the most upstream drum. This localized static elimination ensures that the most upstream photosensitive drum has uniform surface potential comparable to other drums, preventing transfer memory caused by potential differences while maintaining the single power source configuration.
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 configuration prevents transfer memory and reduces the size and cost of the image forming apparatus by ensuring uniform electric currents to all photosensitive drums, maintaining image quality and reducing power consumption.
Implementation Method 1
a plurality of static eliminators are disposed downstream of the respective photosensitive drums in the movement direction of the transfer target and perform static elimination on the respective photosensitive drums located upstream in the movement direction of the transfer target
Implementation Method 2
The plurality of load resistors are connected in parallel to one another and in series between the power source for transfer and the at least two transfer rollers to which the power source for transfer applies potential
Implementation Method 3
The power source for transfer applies potential to each of at least two transfer rollers including a transfer roller located the most upstream in the movement direction of the transfer target among the plurality of transfer rollers
Data Source
AI summary
An image forming apparatus (1) includes photosensitive drums (41y, 41c, 41m, and 41k), static eliminators (45y, 45c, 45m, and 45k), transfer rollers (54y, 54c, 54m, and 54k), a power source (55a) for transfer, and load resistors (47y, 47c, 47m, and 47k). The static eliminators (45y, 45c, and 45m) perform static elimination on adjacently upstream or downstream photosensitive drums (41y, 41c, 41m, and 41k) in a movement direction of a transfer target. The transfer rollers (54y, 54c, 54m, and 54k) are disposed opposite to the respective photosensitive drums (41y, 41c, 41m, and 41k). The power source (55a) for transfer applies potential to the transfer rollers (54y, 54c, 54m, and 54k). The load resistors (57y, 57c, 57m, and 57k) are respectively connected in parallel to one another and in series between the power source (55a) for transfer and the respective transfer rollers (54y, 54c, 54m, and 54k).