Transfer Bias Control for Image Forming Apparatus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses, the distance between transfer sheets is prolonged due to varying transfer outputs, leading to reduced printing throughput and issues like banding and blurring in toner images.
Innovation Solution
The apparatus includes a photosensitive drum, a transfer member, a humidity sensor, a sheet sensor, and a controller. The controller adjusts the transfer bias based on humidity and sheet position, changing the transfer current to reduce disturbances in the toner image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the transfer output is reduced at the trailing end portion of the preceding transfer sheet to prevent banding, then banding is reduced, but blurring occurs in the toner image of the preceding sheet
Solution Approach 1:
The controller changes the transfer bias from the first transfer bias to the second transfer bias a particular period before the trailing end portion of the transfer sheet reaches the transfer position. This preliminary action allows the transfer output to be reduced in advance, preventing banding in the subsequent sheet's toner image while maintaining sufficient transfer output for the current sheet to avoid blurring.
Solution Approach 2:
The transfer bias is dynamically adjusted based on the position of the transfer sheet. The controller switches between the first transfer bias (higher output) and the second transfer bias (lower output) at appropriately timed intervals, creating a dynamic transfer output that adapts to the sheet position and prevents both banding and blurring.
2Object-affected harmful factors
If the output applying section gradually decreases the transfer output while the trailing end portion is conveyed through the transfer position, then banding is prevented, but the distance between transfer sheets becomes long, reducing printing throughput
Solution Approach 1:
The controller applies the first transfer bias and second transfer bias in periodic intervals based on the sheet length and conveyance speed. By switching between the two biases at appropriately timed periods rather than gradually decreasing output, the system prevents banding while minimizing the time the transfer output is reduced, thereby maintaining higher printing throughput.
3Productivity
If the transfer output is maintained at a high level continuously, then printing throughput is improved, but banding occurs in the toner image of the subsequent transfer sheet
Solution Approach 1:
The controller switches to the second transfer bias before the trailing end portion of the current sheet completes its passage through the transfer position. This preliminary reduction in transfer output prevents excessive transfer current from affecting the subsequent sheet's toner image, thereby preventing banding while maintaining high throughput by not extending the low-output period unnecessarily.
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 reduces banding and blurring in toner images, improving printing throughput by optimizing the transfer process based on environmental and sheet-related factors.
Implementation Method 1
a transfer member transfers a toner image formed on the photosensitive drum to a sheet that passes through a transfer position between the photosensitive member and the transfer member
Implementation Method 2
a humidity sensor detects humidity
Data Source
AI summary
A transfer nip is formed between a transfer member and a photosensitive drum. The transfer member is configured to transfer a toner image formed on the photosensitive drum to a sheet that passes through the transfer nip. A humidity sensor is configured to detect humidity. A sheet sensor is arranged upstream of the transfer member in a sheet conveyance direction. The sheet sensor is configured to detect a trailing end of the sheet. A controller is configured to: in response to an elapse of a particular period after the sheet sensor detects the trailing end of the sheet, change a transfer bias to be applied to the transfer member from a first transfer bias to a second transfer bias, the second transfer bias having a smaller absolute value than the first transfer bias; and change the particular period based on the humidity detected by the humidity sensor.