Fur Brush Bias Control for Toner Cleaning Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge of maintaining effective toner cleaning properties with a fur brush in image forming apparatuses, particularly due to reduced outer diameter and increased electrical resistance, leading to decreased cleaning current and potential charging failures, is exacerbated by the use of toner with lower melting points and spherical shapes, causing toner fusion and image defects.
Innovation Solution
An image forming apparatus with a rotatable brush and a control mechanism that dynamically adjusts the cleaning bias based on detected current or voltage, using a detecting portion to apply multiple test biases and set the appropriate voltage for the brush, thereby maintaining effective toner removal regardless of fur brush wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed bias voltage is applied to the fur brush, then the cleaning function is effective when the brush is new, but the cleaning current decreases as the brush wears and outer diameter reduces
Solution Approach 1:
The patent applies a variable bias voltage that dynamically adjusts based on the fur brush's wear state. The control unit changes the bias voltage according to the outer diameter of the fur brush, ensuring optimal cleaning current is maintained throughout the brush's service life, resolving the contradiction between initial effectiveness and long-term reliability.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit monitors the fur brush's outer diameter and adjusts the bias voltage accordingly. This closed-loop control ensures that the cleaning function remains reliable by compensating for wear-induced changes in electrical resistance and contact area.
2Reliability
If the bias voltage is increased to compensate for brush wear, then cleaning current is maintained, but excessive current flows when the brush is new causing positive memory
Solution Approach 1:
The patent uses a dynamic bias voltage adjustment strategy where the voltage is tailored to the fur brush's current state. When the brush is new, a lower voltage prevents positive memory; as the brush wears and resistance increases, the voltage is increased to maintain cleaning current. This resolves the contradiction between maintaining cleaning effectiveness and preventing harmful side effects.
Solution Approach 2:
The patent changes the bias voltage parameter based on the fur brush's outer diameter. By adjusting this electrical parameter according to the mechanical wear state, the system optimizes cleaning current while avoiding excessive current that would cause positive memory, thus resolving the contradiction between cleaning reliability and harm prevention.
3Duration of action of stationary object
If the fur brush outer diameter is reduced due to wear, then the brush can be used longer, but contact width decreases and contact resistance increases
Solution Approach 1:
The patent implements dynamic voltage adjustment that compensates for the changing electrical characteristics of the fur brush during its service life. As the outer diameter reduces and contact resistance increases, the bias voltage is increased to maintain the necessary cleaning current, thereby preserving cleaning reliability throughout the extended service period.
Solution Approach 2:
The patent adjusts the bias voltage parameter in response to changes in the fur brush's physical dimensions. By correlating voltage settings with brush outer diameter, the system maintains effective cleaning current despite increasing contact resistance, resolving the contradiction between extended service life and sustained cleaning performance.
4Productivity
If toner with lower melting point and spherical shape is used, then image quality and speed are improved, but toner fusion occurs more easily at the blade nip
Solution Approach 1:
The patent applies a bias voltage to the fur brush in advance to remove toner before it reaches the blade nip region. This preliminary cleaning action prevents toner accumulation and subsequent fusion at the high-stress blade contact area, resolving the contradiction between using low-melting-point spherical toner for high-speed printing and preventing toner fusion defects.
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 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 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 3
the contact resistance (electrical resistance) between the photosensitive member and the fur brush increases
Data Source
Figure 1
Figure 2
Figure 3
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.