Photosensitive Drum Cleaning With Wear-Adaptive Fur-Brush Bias
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Solution Overview
Problem
The challenge of maintaining effective toner cleaning properties with a fur brush in image forming apparatuses, especially due to fiber collapse and increased electrical resistance, leading to reduced cleaning current and potential charging failures, is exacerbated by the use of low-melting toner and spherical toner shapes, which cause toner fusion and image defects.
Innovation Solution
An image forming apparatus with a rotatable brush and a control system that detects current or voltage through the brush, applying multiple test biases to set an appropriate cleaning bias, thereby adjusting the applied voltage based on detected results to maintain effective toner removal and prevent charging failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed bias voltage is applied to the fur brush, then the cleaning function is simple and reliable, but the cleaning current decreases as the brush wears, leading to reduced cleaning performance
Solution Approach 1:
The patent implements a feedback control system where a detection unit measures the actual current flowing through the fur brush during cleaning operation. The control unit receives this current information and adjusts the bias voltage applied to the fur brush in real-time to maintain the cleaning current within a predetermined effective range. This closed-loop feedback mechanism ensures consistent cleaning performance despite brush wear, outer diameter changes, or contact resistance variations.
2Reliability
If the bias voltage is increased to compensate for increased contact resistance, then cleaning current is maintained, but excessive current may cause positive memory in the photosensitive member
Solution Approach 1:
The feedback control system continuously monitors the actual cleaning current and adjusts the bias voltage only to the extent necessary to maintain the current within the effective cleaning range. This precise control prevents over-compensation that would cause excessive current flow and positive memory, while still addressing the increased contact resistance from brush wear.
Solution Approach 2:
The patent dynamically changes the bias voltage parameter based on real-time cleaning current measurements. By adjusting this electrical parameter in response to brush wear conditions, the system maintains optimal cleaning current without exceeding safe limits that would damage the photosensitive member.
3Reliability
If the fur brush outer diameter decreases due to fiber collapse, then the contact width with photosensitive member reduces, but increasing bias voltage to compensate risks causing positive memory
Solution Approach 1:
The feedback control system directly responds to the actual cleaning current condition rather than predicting brush wear. When fiber collapse reduces contact width and increases resistance, the system measures the resulting current drop and adjusts bias voltage precisely to compensate, avoiding both insufficient cleaning and excessive current that would cause positive memory.
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
The system ensures consistent toner cleaning performance by adapting the cleaning bias to the fur brush's condition, preventing toner fusion and charging failures, thus maintaining image quality and apparatus longevity.
Implementation Method 1
By applying a bias to the fur brush, at least a part of the transfer residual toner before it reaches the cleaning blade can be removed from the surface of the photosensitive member by the fur brush
Implementation Method 2
the current (cleaning current) required for collecting the toner does not flow between the fur brush and the photosensitive member
Implementation Method 3
the method in which the transfer residual toner is scraped off from the surface of the photosensitive member by rubbing the surface of the photosensitive member with the cleaning blade
Implementation Method 4
the toner present in the vicinity of the blade nip melts and adheres to the photosensitive member
Implementation Method 5
a charging device configured to charge a surface of the photosensitive member at a charging position
Implementation Method 6
a transfer device configured to transfer toner to a transferred member from the surface of the photosensitive member at a transfer position
Data Source
AI summary
An image forming apparatus includes a photosensitive drum, a charging device, a charge bias applying portion, a transfer device, a transfer bias applying portion, a cleaning blade in contact with the surface of the photosensitive member at a blade cleaning position downstream of a transfer position and upstream of a charging position, a rotatable brush in contact with the surface at a brush cleaning position downstream of the transfer position and upstream of a blade cleaning position, and a cleaning bias applying portion. A controller during non-image formation, causes the cleaning bias applying portion to apply test biases to the brush and to perform a setting operation in which a voltage to be applied by the cleaning bias applying portion is set based on a detecting result of a current flowing through the brush or a voltage applied to the brush when test biases are applied.