Image Forming Apparatus Developing Bias Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image forming apparatuses face challenges in suppressing image density unevenness due to output upper and lower limits of the developing power supply, particularly when changing the developing bias across the rotation cycle of photoconductors and developing sleeves, leading to unsynchronized image density variations.
Innovation Solution
An image forming apparatus comprising an imaging device, a transferrer, a rotator, a rotation position sensor, an adhesion amount sensor, and a controller that constructs output pattern data to adjust the voltage output from the power supply based on detection results from the adhesion amount and rotation position sensors, allowing for voltage changes within the power supply's range to effectively suppress image density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the developing bias is changed according to the output pattern data to suppress image density unevenness, then image density uniformity is improved, but the suppression fails when the required bias value exceeds the power supply's output upper or lower limit
Solution Approach 1:
The patent applies dynamics by making the developing bias dynamically adjustable throughout the rotation cycle of the photoconductor. The controller changes the developing bias according to output pattern data that corresponds to different rotation positions, allowing the bias to be optimized at each position to compensate for density unevenness caused by eccentricity or external distortion. This dynamic adjustment ensures reliable suppression of image density unevenness even when the required bias values approach or exceed the power supply limits, as the system adapts the bias in real-time rather than using a fixed value.
2Reliability
If the developing bias is constrained within the power supply's output range, then the power supply operates reliably, but image density unevenness cannot be fully suppressed when the optimal bias value lies outside the output range
Solution Approach 1:
The patent applies parameter changes by modifying the developing bias parameter according to the rotation position of the photoconductor. The output pattern data stores predetermined bias adjustment values corresponding to different angular positions, and the controller applies these adjustments cyclically as the photoconductor rotates. This allows the system to optimize image density uniformity by changing the bias parameter in sync with the rotation cycle, compensating for periodic variations caused by mechanical imperfections while keeping the bias within the power supply's operational range.
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
An image forming apparatus includes an imaging device (18), a transferrer (30), a rotator (20, 81), a rotation position sensor (76, 83), an adhesion amount sensor (150), a power supply (11, 12), and a controller (110). The controller (110) executes a construction process to construct output pattern data to change a voltage output from the power supply, according to a result obtained by detecting a toner adhesion amount of a toner image for density unevenness detection and a detection result from the position sensor obtained when the toner image is formed, and an output change process to execute a process while changing the voltage according to the detection result and the data. The controller executes a determination process to determine propriety of a range of the voltage output by the output change process and a data process for a shift to shift the range when a determination result is inappropriate.