Image Forming Apparatus Voltage Sequencing for Post-Rotation Fog Control
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Solution Overview
Problem
Existing image forming apparatuses without developing contact and separation mechanisms experience fog due to toner deposition on non-image portions during post-rotation operations, complicating the apparatus constitution and hindering downsizing and cost reduction.
Innovation Solution
An image forming apparatus with a controller that controls charging, developing, and transfer voltages to maintain a predetermined potential difference range during post-rotation operations, ensuring the developing member remains in contact with the image bearing member, thereby suppressing fog and toner consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the developing roller and photosensitive drum are always in contact state to simplify the apparatus constitution, then the device complexity is reduced, but fog occurs due to toner deposition on non-image portions during post-rotation operations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the developing voltage during post-rotation operations. Specifically, the developing voltage is reduced to a first developing voltage during post-rotation, which changes the electrical parameter to prevent toner deposition on non-image portions while maintaining the contact state between developing roller and photosensitive drum, thus suppressing fog without complicating the apparatus constitution
Solution Approach 2:
The patent implements dynamics by making the developing voltage adjustable and time-dependent. The developing voltage is set to a first developing voltage during post-rotation operations and a second developing voltage during image forming operations, allowing the system to adapt to different operational states and prevent fog during idle periods while maintaining effective development during active use
2Object-generated harmful factors
If the developing contact and separation mechanism is provided to prevent fog during post-rotation operations, then fog is suppressed, but the device complexity and size increase
Solution Approach 1:
The patent replaces the mechanical contact and separation mechanism with an electrical control solution. Instead of using mechanical means to separate the developing roller from the photosensitive drum during post-rotation, the system uses voltage control to prevent toner deposition, thereby eliminating the need for additional mechanical components and reducing device complexity
Solution Approach 2:
The patent extracts the fog prevention function from the mechanical contact and separation mechanism. By controlling the developing voltage during post-rotation operations, the system achieves fog suppression without requiring the physical separation of the developing roller, thus removing the need for complex mechanical separation mechanisms
3Loss of substance
If the developing roller is separated from the photosensitive drum during post-rotation operations to prevent fog, then toner consumption due to fog is reduced, but the apparatus constitution becomes complicated and upsized
Solution Approach 1:
The patent uses parameter changes by adjusting the developing voltage during post-rotation operations to prevent toner deposition. By reducing the developing voltage to a first developing voltage during post-rotation, the system prevents toner transfer to non-image portions, thereby reducing toner consumption without requiring mechanical separation that would complicate the apparatus constitution
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
Effectively suppresses fog during post-rotation operations, simplifies the apparatus constitution, and reduces toner consumption without complicating control or increasing costs.
Implementation Method 1
a charging member configured to electrically charge a surface of the image bearing member to a predetermined polarity
Implementation Method 2
a developing member contacting the surface of the image bearing member and configured to form a toner image by supplying toner to the surface of the image bearing member
Implementation Method 3
a transfer member contacting the surface of the image bearing member and configured to transfer the toner image from the image bearing member onto a recording material
Data Source
AI summary
In an image forming apparatus, rotation of an image bearing member is started and stopped in a contact state between the image bearing member and a developing member. During a post-rotation operation, a controller ends application of a charging voltage after changing the charging voltage stepwisely to first and second charging voltages. The controller ends application of a developing voltage after changing the developing voltage stepwisely at a developing position to first and second developing voltages in synchronism with the first and second charging voltages. A potential difference between each of surface potentials of first and second regions and an associated one of the first and second developing voltages is maintained within a predetermined range. The controller carries out control so that an absolute value of the surface potential of at least one of the first and second regions is made low by passing a current under application of a transfer voltage.