Dynamic Transfer Voltage Control for Image Forming Apparatus
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Solution Overview
Problem
Image forming apparatuses face issues with setting optimal secondary transfer voltage due to varying sheet resistance values, leading to potential image defects and increased workload in optimizing transfer conditions, as existing systems either restrict the voltage range unnecessarily or fail to reflect user settings accurately.
Innovation Solution
An image forming apparatus equipped with a current detection unit and control unit that adjusts the upper limit voltage based on detected currents during a test bias application, allowing for dynamic setting of transfer bias to prevent excessive voltage and ensure proper image transfer without narrowing the voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection circuit is provided to prevent overcurrent, then heat generation and substrate failure are prevented, but image defects occur due to intermittent oscillation operation
Solution Approach 1:
The control unit performs preliminary detection of the secondary transfer portion impedance before image formation, and pre-calculates the appropriate secondary transfer voltage based on the detected impedance. This preliminary action ensures that the correct voltage is applied from the start, preventing overcurrent conditions that would trigger the protection circuit and cause image defects.
Solution Approach 2:
The control unit detects the impedance of the secondary transfer portion and uses this feedback information to dynamically adjust the secondary transfer voltage. This closed-loop feedback mechanism ensures that the voltage always matches the actual impedance conditions, preventing overcurrent while maintaining optimal image transfer.
2Reliability
If the upper limit of secondary transfer voltage is set uniformly, then overcurrent is prevented, but the setting range is unnecessarily narrowed and optimum transfer conditions cannot be selected
Solution Approach 1:
The control unit dynamically determines the upper limit voltage for secondary transfer based on the detected impedance of the secondary transfer portion. Instead of using a fixed uniform limit, the system adjusts the voltage limit in real-time according to actual conditions, allowing the full usable voltage range to be utilized while preventing overcurrent.
Solution Approach 2:
The control unit changes the secondary transfer voltage parameter based on the detected impedance value. By calculating the appropriate voltage limit from the actual impedance measurement, the system adapts the voltage parameter to match the specific sheet resistance conditions, enabling both safety and optimality.
3Ease of operation
If the user sets secondary transfer voltage freely within high voltage guarantee range, then user control is maximized, but excessive voltage may be applied causing overcurrent
Solution Approach 1:
The control unit uses feedback from the impedance detection to automatically adjust and limit the secondary transfer voltage, even when the user sets a high voltage value. The detected impedance information provides feedback that enables the control unit to prevent excessive voltage application while still allowing the user to access the full control interface.
Solution Approach 2:
The control unit performs self-protection by automatically detecting impedance and limiting voltage output based on the detected conditions. This self-service mechanism protects the system from user-induced overcurrent conditions without requiring the user to understand the complex relationships between voltage, impedance, and current.
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 enables the user to set transfer voltage effectively while minimizing image defects and reducing the workload associated with optimizing image quality, by dynamically adjusting the voltage range based on current detection during non-image forming periods.
Implementation Method 1
a bias applying portion configured to apply a transfer bias to the transfer portion, the toner image borne on the image bearing member being transferred to a recording material passing through the transfer portion by the bias applying portion applying the transfer bias to the transfer portion
Implementation Method 2
a current detection unit configured to detect a current supplied to the transfer portion
Data Source
AI summary
An image forming apparatus includes an image bearing member, a transfer body, a bias applying portion, a current detection unit, and a control unit. The control unit is configured to change the upper limit voltage based on the current detected by the current detection unit in a state where a test bias is applied to the transfer portion during a non-image forming period, and a voltage of the test bias being applied.