Image Forming Apparatus Charger Control for Wear Reduction
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Solution Overview
Problem
Image forming apparatuses face deterioration of the charger due to frequent discharge current control, especially when the device is used infrequently, leading to premature wear and the need for frequent replacement of the charging member or process cartridge.
Innovation Solution
An image forming apparatus with a photosensitive member, a charger, a bias applying device, a detector, and a regulator that adjusts the charging bias based on detected currents during a test mode, allowing for selective discharge current control modes to minimize charger wear, including a simple control mode that reduces the number of applied voltage points and current measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discharge current control is carried out every turning-on of the power switch or every start of image formation after a lapse of predetermined time, then electric resistance fluctuation of the charging member is stabilized, but the charging member deteriorates due to excessive energization time
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the discharge current control frequency based on the actual usage conditions. Instead of fixed periodic control, the system monitors image formation sheet numbers and time intervals, switching between full discharge current control (at power-on or after long idle periods) and simplified control (during active usage), thereby optimizing both electric resistance stability and charging member lifetime
Solution Approach 2:
The patent implements dynamic control by making the discharge current control frequency adaptable to usage patterns. The system transitions from static periodic control to dynamic control that adjusts its behavior based on whether the apparatus is actively being used or idle, ensuring reliability when needed while minimizing wear during normal operation
2Manufacturing precision
If discharge current control is carried out frequently to stabilize electric discharge, then charging uniformity is improved, but the proportion of energization time becomes large relative to image formation time
Solution Approach 1:
The patent changes the control parameters by implementing different discharge current control strategies based on usage state. During active image formation, the system uses simplified control with fewer voltage points, reducing energization time proportion. During idle periods or power-on, full control is applied to ensure charging uniformity, thus optimizing the balance between precision and energy consumption
3Measurement precision
If multiple test biases are applied in test mode to regulate charging bias, then discharge current control precision is improved, but the number of voltage applications and current measurements increases
Solution Approach 1:
The patent segments the discharge current control into two distinct modes: full test mode with multiple voltage points applied during power-on or idle periods, and simplified check mode with fewer voltage points during active usage. This segmentation allows high precision control when needed while reducing complexity during normal operation, resolving the contradiction between measurement precision and device complexity
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 prolongs the lifespan of the charging device by optimizing discharge current control, reducing unnecessary wear and extending the operational life of the charger, even when the device is used intermittently.
Implementation Method 1
a detector for detecting a current passing through the charger
Implementation Method 2
a regulator for regulating a peak-to-peak voltage of the charging bias on the basis of a current detected by the detector
Implementation Method 3
a charger for electrically charging the photosensitive member when an image is formed on the photosensitive member
Data Source
AI summary
An image forming apparatus capable of suppressing deterioration of a charger although an amount of use of the charger is actually small is provided. For that purpose, the image forming apparatus executes simple control of discharge current control in which at least one charging bias smaller in number than number of kinds of test biases in full control of the discharge current control is applied to the charger after a power source is turned on and before an image formation start signal is inputted, and on the basis of a current detected by the detector when the charging bias is applied, selects one from a plurality of modes including a first mode in which a charging bias is set by executing the full control of the discharge current control and including a second member in which the charging bias determined by full control of discharge current control without executing the full control of the discharge current control.