Transfer Bias Control for Image Forming Apparatus
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Solution Overview
Problem
Image forming apparatuses face challenges in transferring toner images onto transfer materials with varying resistance values, as existing methods like ATVC are inefficient for a wide range of resistance values, leading to defective prints and reduced transfer efficiency.
Innovation Solution
The apparatus includes a current detecting unit to set an upper limit of transfer current and control the transfer bias voltage, ensuring the transfer current does not exceed this limit, and in a second embodiment, a pre-transfer guide member is connected to ground to detect guiding current, allowing for differential current control to optimize transfer efficiency across a broader range of resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant current control is performed during non-transfer time with ATVC method, then transfer bias voltage can be controlled for standard transfer materials, but transfer efficiency deteriorates when used with transfer materials having resistance values outside the designed range
Solution Approach 1:
The patent implements dynamic adjustment of transfer bias voltage based on real-time detection of transfer current. The control unit continuously monitors transfer current during the transfer process and adjusts the transfer bias voltage dynamically to maintain optimal transfer conditions across different transfer material resistance values, transforming the static ATVC method into a dynamic adaptive system.
Solution Approach 2:
The patent introduces a feedback mechanism where the detected transfer current is fed back to the control unit, which then adjusts the transfer bias voltage accordingly. This closed-loop feedback system enables the apparatus to automatically adapt to different transfer material resistance values by comparing actual transfer current with target values and correcting the transfer bias voltage to maintain optimal transfer efficiency.
2Productivity
If transfer bias voltage is increased to improve transfer efficiency, then transfer current increases, but this causes defective prints when transfer material resistance is low
Solution Approach 1:
The control unit uses feedback from the detected transfer current to regulate the transfer bias voltage. When transfer current exceeds the target value (indicating low resistance material), the control unit reduces the transfer bias voltage to prevent defects. This feedback control ensures that transfer efficiency is maintained without compromising print quality across different resistance values.
Solution Approach 2:
The patent dynamically changes the transfer bias voltage parameter based on the detected transfer current characteristics. By adjusting this electrical parameter in real-time according to the transfer material's resistance properties, the system optimizes both transfer efficiency and print quality for each specific transfer material type.
3Manufacturing precision
If transfer bias voltage is decreased to prevent defects on low resistance materials, then transfer efficiency improves for those materials, but transfer fails on high resistance materials
Solution Approach 1:
The system dynamically adjusts transfer bias voltage based on real-time detection of transfer current characteristics. For high resistance materials where transfer current is low, the control unit increases the transfer bias voltage to ensure complete transfer. This dynamic adaptation allows the same system to optimize for both low resistance (preventing defects) and high resistance (ensuring transfer) conditions.
Solution Approach 2:
The control unit changes the transfer bias voltage parameter in response to detected transfer current levels. When transfer current is below the target value (indicating high resistance material), the system increases the transfer bias voltage to compensate, ensuring adequate transfer efficiency while maintaining print quality.
4Device complexity
If a fixed transfer bias voltage is used for all transfer materials, then device complexity is reduced, but transfer efficiency and print quality deteriorate across varying resistance values
Solution Approach 1:
The system performs self-adjustment by automatically detecting transfer current and regulating its own transfer bias voltage without external intervention. The control unit uses the detected transfer current information to self-correct the transfer bias voltage, enabling the apparatus to adapt to different transfer materials autonomously while maintaining reliable transfer across varying resistance values.
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 enables high-quality image printing on a wider range of transfer materials with varying resistance values by determining appropriate upper limits of transfer current based on measured resistance values, improving transfer efficiency and print quality.
Implementation Method 1
a transfer bias voltage is applied to the secondary transfer roller... The composite toner image on the transfer belt is transferred onto the transfer material introduced to the transfer nip
Implementation Method 2
a current detecting unit that detects transfer current flowing from the voltage application unit to the transfer material
Data Source
AI summary
An image forming apparatus having: an image support that supports a toner image; a transfer member adapted to sandwich with the transfer member and the image support; a voltage application unit that applies a transfer bias voltage to the transfer member; a current detecting unit that detects transfer current flowing from the voltage application unit to the transfer material after transfer processing on the transfer material starts; and a control unit that sets an upper limit of transfer current on the basis of a value of the transfer current detected by the current detecting unit, and thereafter further acquires a transfer current value from the current detecting unit to control a transfer bias voltage generated by the voltage application unit, such that the transfer current value during transfer does not exceed the upper limit.