Print Blanket Bias Voltage Control for LEP Null Cycles
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Solution Overview
Problem
In liquid electro-photography (LEP) printing devices, the high bias voltage applied to the print blanket during normal printing causes corona breakdown and plasma formation, leading to damage and reduced print quality, while null cycles exacerbate these issues due to increased current flow and dryness, necessitating a solution to minimize these effects.
Innovation Solution
The system detects the onset of a null cycle and proactively adjusts the bias voltage to a level below the Paschen voltage threshold, preventing plasma formation and damage by reducing the voltage to a value above the residual V-light voltage, thereby minimizing wear and extending the print blanket's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high bias voltage is applied to the print blanket during normal printing, then image transfer quality is improved, but corona breakdown and plasma formation occur causing damage to the print blanket
Solution Approach 1:
The patent applies dynamic voltage adjustment by switching between a higher bias voltage during normal printing operations to maintain image transfer quality and a lower bias voltage during null cycles to prevent corona breakdown and plasma formation. The system dynamically adapts the voltage level based on the operational state, resolving the contradiction between maintaining transfer quality and preventing damage.
Solution Approach 2:
The patent changes the bias voltage parameter from a static high value to a dynamic value that adjusts based on operational conditions. During null cycles, the voltage is reduced to below the Paschen voltage threshold, preventing harmful plasma formation while still maintaining sufficient voltage above the V-light residual voltage to avoid other issues, thus resolving the contradiction between transfer quality and damage prevention.
2Speed
If high bias voltage is applied during null cycles, then the system remains ready for immediate printing, but current flow increases and plasma formation causes accelerated wear to the print blanket
Solution Approach 1:
The system dynamically adjusts the bias voltage based on the operational state. During null cycles when printing is suspended, the voltage is reduced to prevent plasma formation and minimize current flow, thereby reducing wear on the print blanket. When printing resumes, the voltage is increased again to ensure proper image transfer, thus balancing readiness with lifespan extension.
Solution Approach 2:
The patent applies preliminary action by proactively reducing the bias voltage before plasma formation can occur during null cycles. This preventive measure extends the print blanket lifespan while the system remains in a ready state, and the voltage is restored when needed for printing, resolving the contradiction between readiness and durability.
3Object-affected harmful factors
If bias voltage is reduced during null cycles, then plasma formation and wear are minimized, but voltage must remain above V-light residual voltage to maintain operational readiness
Solution Approach 1:
The patent precisely controls the bias voltage parameter within a specific range during null cycles: above the V-light residual voltage to maintain operational readiness and below the Paschen voltage threshold to prevent plasma formation. This narrow parameter window resolves the contradiction by finding the optimal voltage level that satisfies both requirements simultaneously.
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 adjustment reduces damage to the print blanket during null cycles by minimizing current flow and plasma formation, maintaining image transfer quality, and extending the useful lifespan of the print blanket.
Implementation Method 1
The transfer of the ink image from the photoreceptor to the image transfer element is driven by a nip contact and an electric field created by a bias voltage applied to the transfer element
Implementation Method 2
the high bias voltage applied to the print blanket during normal printing causes corona breakdown and plasma formation
Implementation Method 3
the high bias voltage applied to the print blanket during normal printing causes corona breakdown and plasma formation
Data Source
AI summary
In an example, a method of controlling voltage applied to a print blanket within a printing device includes printing a print job. During the printing, a null cycle trigger is received. In response to the trigger, a print blanket bias voltage is reduced from a print bias level to a null bias level.