Transfer Bias Control for Faster First Copy Output in Image Forming
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Solution Overview
Problem
Conventional Active Transfer Voltage Control (ATVC) methods require a significant downtime due to the need for applying test biases over multiple circumferences of the transfer roller to account for resistance variations, which is inefficient for modern image forming apparatuses requiring faster First Copy Output Time (FCOT) and accurate transfer bias control.
Innovation Solution
An image forming apparatus with a controller that applies a first test bias for a shorter time followed by a second test bias of higher absolute value, allowing for quicker acquisition of voltage-current characteristics to set the transfer bias accurately, thereby reducing control time without compromising accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If test biases are applied over multiple circumferences of the transfer roller to account for resistance variations, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent applies preliminary action by performing resistance value measurements at multiple predetermined positions (0°, 60°, 120°, 180°, 240°, 300°) around the transfer roller before image formation. This preliminary measurement captures circumferential resistance variations without requiring multiple full circumferences of operation, thereby reducing the time penalty while maintaining measurement precision. The controller stores these position-specific resistance values for later use in transfer bias control.
Solution Approach 2:
The patent segments the measurement process by dividing the transfer roller's circumference into six discrete measurement positions (0°, 60°, 120°, 180°, 240°, 300°). Instead of continuously measuring over multiple full circumferences, the system takes discrete samples at these segmented positions. This segmentation reduces the total measurement time while still capturing the resistance variations throughout the roller's circumference, resolving the contradiction between precision and time loss.
2Manufacturing precision
If test biases are applied to account for circumferential resistance unevenness, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The system performs preliminary resistance measurements at six predetermined positions around the transfer roller before image formation begins. This preliminary action captures the circumferential resistance unevenness characteristics without requiring multiple full circumferences of operation. The controller stores these measurements and uses them to adjust transfer bias voltages, thereby improving manufacturing precision while minimizing the impact on productivity by completing measurements quickly during idle time.
Solution Approach 2:
The patent implements dynamic transfer bias control by adjusting the transfer bias voltage based on the measured resistance values at different circumferential positions. The controller dynamically selects appropriate bias voltages from a plurality of levels according to the detected resistance characteristics at each position. This dynamic adjustment improves manufacturing precision by adapting to actual resistance variations while maintaining productivity through efficient, position-specific control rather than conservative multi-circumference testing.
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 approach significantly shortens the control time for transfer bias adjustment while maintaining high accuracy, aligning with the demand for faster FCOT in multi-function machines without compromising image quality.
Implementation Method 1
The transfer roller is constituted so as to have an electric resistance value of, for example, about 1×10^6 to 1×10^10Ω
Implementation Method 2
a transfer bias is applied to a transfer member when a recording material as the toner image receiving member passes through a transfer portion formed in a contact portion between the image bearing member and the transfer member, so that the toner image is transferred from the image bearing member onto the recording material by the action of an electric field formed in the transfer portion
Data Source
AI summary
An image forming apparatus includes an image bearing member, a transfer member, an applying portion, a detecting portion, and a controller. In a case where an adjusting operation is executed from reception of a start signal of image formation to a start of transfer of an image on a first sheet in the transfer portion, the controller controls the applying portion so that a second test bias is higher in absolute value of a voltage than a first test bias and controls the applying portion so that a time in which the first test bias is applied to the transfer portion is set to a first time and so that a time in which the second test bias is applied to the transfer portion is set to a second time longer than the first time.