Voltage Control in Liquid Electrophotographic Printer Cleaner Roller
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Solution Overview
Problem
Electrophotographic printing systems experience a print quality defect known as the PQ set phenomenon, where unintended ink transfer occurs due to sudden changes in ink layer thickness, resulting in a 'ghost' artefact on the printed substrate, particularly noticeable when printing solid lines.
Innovation Solution
The implementation of a controller that measures and adjusts the voltage applied to the cleaner roller to maintain a consistent potential difference with the developer roller, predicting and mitigating the PQ set defect by adjusting the cleaner roller voltage based on measured current peaks and angular velocities within the Binary Ink Developer (BID) unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage applied to the cleaner roller is increased to improve ink removal efficiency, then the cleaner roller can more effectively remove excess ink from the developer roller, but this causes unintended ink transfer and PQ set defects on the printed substrate
Solution Approach 1:
The patent applies dynamics by making the cleaner roller voltage adjustable and time-dependent. The voltage is dynamically modified based on detected current peaks from the developer roller, allowing the system to adapt the cleaning strength in real-time. This resolves the contradiction by enabling high voltage for effective cleaning when needed, while reducing voltage when it would cause harmful ink transfer, thus balancing ink removal efficiency with prevention of unintended ink transfer.
Solution Approach 2:
The patent implements feedback by monitoring the current between the developer roller and ground, detecting current peaks that indicate ink layer thickness changes, and using this information to adjust the cleaner roller voltage. The feedback loop continuously adjusts the cleaning voltage based on actual operating conditions, ensuring effective ink removal while preventing the PQ set defect caused by excessive voltage.
2Stability of the object's composition
If the cleaner roller voltage is maintained at a high level to ensure consistent cleaning performance, then ink removal remains effective, but the PQ set phenomenon occurs due to sudden changes in electrical properties when ink layer thickness varies
Solution Approach 1:
The system transitions from a static high voltage approach to a dynamic voltage adjustment approach. By continuously monitoring developer roller current and detecting peaks that indicate ink layer changes, the system dynamically adjusts the cleaner roller voltage to maintain appropriate cleaning effectiveness while preventing the electrical property sudden changes that cause PQ set defects and print quality issues.
Solution Approach 2:
The patent applies preliminary action by detecting current peaks in advance that indicate upcoming changes in ink layer thickness. When a current peak is detected, the system proactively modifies the cleaner roller voltage before the actual cleaning occurs, preventing the PQ set defect from happening in the first place while maintaining consistent cleaning performance.
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 effectively reduces or eliminates the PQ set defect by maintaining controlled electrical properties, ensuring consistent ink transfer and improving print quality by preventing unintended ink transfer during the printing of solid lines.
Implementation Method 1
controlling a voltage applied to the cleaner roller to maintain a potential difference between the cleaner roller and the developer roller
Implementation Method 2
measuring a current associated with an image development unit of the liquid electrophotographic printer
Data Source
AI summary
A method of printing images in a liquid electrophotographic printer is provided. In an example, the method includes measuring at least one current associated with an image development unit of the liquid electrophotographic printer. A first time at which a peak occurs in the measured current is determined; the first time indicates that a printing substance is transferred from a point on a developer roller of the image development unit to a photo imaging member of the liquid electrophotographic printer at a first location within the image development unit. A second time at which said point on the developer roller is expected to contact the cleaner roller within the image development unit is calculated and, at the second time, a voltage applied to the cleaner roller is controlled to reduce the potential difference between the cleaner roller and the developer roller.