Adjustable Star Wheel Biaser for Inkjet Media Feed
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Solution Overview
Problem
Inkjet imaging device media feed systems with fixed star wheel bias experience excessive wear and contamination due to non-adjustable contact with media and ink, leading to print defects and inefficiencies.
Innovation Solution
A media feed system with an adjustable directional biaser mechanism that allows for varying biasing forces and directions to optimize star wheel positioning, reducing contact with ink and accommodating different media properties, featuring a lever, cam, and motor system controlled by a controller to adjust the biasing forces applied to the star wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If star wheels continuously contact media and ink to advance pages, then media feeding function is achieved, but excessive wear and contamination occurs
Solution Approach 1:
The biasing force applied to the star wheel is made dynamically adjustable rather than fixed. A motorized actuator modifies the spring biasing force based on detected ink density and media properties, allowing the star wheel contact pressure to adapt in real-time. This reduces wear and contamination by minimizing contact when ink density is low while maintaining adequate contact for reliable media feeding when needed.
Solution Approach 2:
The system changes the physical parameter of biasing force magnitude based on operating conditions. By detecting ink density and media properties, the controller adjusts the biasing force parameter to optimize the balance between media feeding reliability and star wheel contamination prevention.
2Device complexity
If fixed biasing force is applied to star wheel, then simple structure is maintained, but cannot accommodate different media properties
Solution Approach 1:
The biaser structure incorporates a motorized actuator that dynamically adjusts the biasing force applied to the spring-loaded star wheel. This transformation from a static to dynamic system enables adaptation to various media properties including thickness, stiffness, and surface characteristics, while maintaining a relatively compact form factor.
Solution Approach 2:
The system employs feedback control where media properties and ink density are detected by sensors, and this information is used by the controller to adjust the biasing force accordingly. This closed-loop feedback mechanism enables the biaser to adapt to different media types automatically.
3Productivity
If star wheel has excessive contact with wet ink, then media feeding is ensured, but ink buildup and print defects occur
Solution Approach 1:
The system dynamically changes the biasing force parameter in response to detected ink density levels. When high ink density is detected, the biasing force is reduced to minimize star wheel contact with wet ink, preventing ink buildup and subsequent print defects. When ink density is low, the biasing force is increased to ensure reliable media feeding.
Solution Approach 2:
The system uses ink density detection to convert the potentially harmful effect of ink contact into a beneficial control signal. By detecting ink presence and density, the system intelligently adjusts star wheel contact pressure to prevent contamination while maintaining feeding functionality.
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
The adjustable biaser minimizes wear and contamination, enhances media feeding efficiency, and reduces print defects by optimizing the interaction between the star wheel and media, accommodating various media types and properties.
Implementation Method 1
a first cam coupleable to a motor
Implementation Method 2
a first biasing member holding the first lever against the first cam
Implementation Method 3
a first cam coupleable to a motor
Data Source
AI summary
A print media feed system in a inkjet printer, the system has a media feed roll, a star wheel mounted opposing the roll, an adjustable biaser coupled to the star wheel, and a controller coupled to the biaser. The controller varies a magnitude, a direction or a magnitude and direction of a biasing force applied to the star wheel by the biaser. In one form, the biaser comprises a motor driven cam that varies the angular position of a pivotable lever having a star wheel rotatably attached on one end. In another form, a rack and pinion gear assembly is used to vary the biasing force with a star wheel rotatably attached to the rack. In a further form, a solenoid is used to vary the basing force applied to the lever or applied to a star wheel rotatably attached to the end of the shaft of a solenoid.