Transfer Member Voltage Control for Image Forming Apparatus Startup Fog
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Solution Overview
Problem
The existing image forming apparatus using the one-component developing method experiences start-up fog, leading to increased toner consumption and image defects due to toner adhering to the photosensitive drum during startup operations, which is difficult to eliminate despite previous methods.
Innovation Solution
An image forming apparatus with a control unit that applies a first voltage of the same polarity as the normal charging polarity to the transfer member during startup, then changes it to a second voltage with a lower absolute value, synchronizing this voltage change with the positions of the photosensitive drum and developing roller to prevent toner adhesion and movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a voltage is applied to the transfer member during startup operation, then toner adhesion to the photosensitive drum is reduced, but image defects occur due to improper voltage timing
Solution Approach 1:
The control unit applies a first voltage to the transfer member before the charged area reaches the transfer position, in advance of when toner transfer is needed. This preliminary voltage application prevents start-up fog by repelling toner from the uncharged area before it can adhere to the photosensitive drum, while the timing control ensures image quality is maintained by switching to the second voltage at the appropriate moment
Solution Approach 2:
The patent implements dynamic voltage control by switching between two different voltage states (first voltage with same polarity as charging, second voltage with opposite polarity) based on the real-time position of the photosensitive drum. This dynamic adjustment allows the system to optimize for both preventing toner adhesion during startup and maintaining image quality during normal operation
2Object-generated harmful factors
If the developing roller is separated from the photosensitive drum, then start-up fog is suppressed, but image formation is delayed
Solution Approach 1:
Instead of changing the physical position or separation state of the developing roller, the patent changes the electrical parameter (voltage polarity and magnitude) applied to the transfer member. By adjusting the voltage from a first voltage with the same polarity as the charging voltage to a second voltage with opposite polarity, the system suppresses start-up fog through electrostatic control while maintaining continuous contact between the developing roller and photosensitive drum for immediate image formation
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 start-up fog and associated image defects, reducing toner consumption and extending the lifespan of the cleaning blade by minimizing electrostatic adhesion forces and ensuring clean transfer operations.
Implementation Method 1
a transfer voltage having a polarity opposite to a normal charging polarity of the toner is applied through the transfer member to the intermediate transfer member, thereby allowing the toner image to be transferred from the photosensitive drum to the intermediate transfer member
Implementation Method 2
the toner on the development member is frictionally charged
Implementation Method 3
a developing voltage is applied to the development member, thereby causing the toner to move to the photosensitive drum with an electrical force
Data Source
AI summary
An image forming apparatus includes a photosensitive member, a transfer member, a transfer power source, and a control unit. At a start time of a start-up operation at the time of starting an image forming operation, on the surface of the photosensitive member, a first position coincides with a charging position, and a third position coincides with a transfer position. During a period in which an area on the photosensitive member located between the first position and the third position in a rotation direction of the photosensitive member passes the transfer position, the control unit performs control of applying a first voltage having the same polarity as a normal charging polarity of toner to the transfer member by the transfer power source, and, at a predetermined timing, changing a voltage from the first voltage to a second voltage having an absolute value less than that of the first voltage.