Piezoelectric Steering Mirror for ROS Scan Line Error Correction
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Solution Overview
Problem
Raster output scanners (ROS) face issues with scan line spacing variations, bow, and skew, which degrade print quality, especially in color printing, and existing correction methods are either expensive or limited by resonant frequency, preventing seamless integration of multiple ROS systems for wider formats.
Innovation Solution
A low-cost micromachined piezoelectric steering element, known as an agile beam steering mirror, dynamically corrects scan line spacing errors, skew, and bow by using a micromachined silicon mirror mounted on a cantilevered piezoelectric bimorph actuator with capacitive sensing and air damping to reduce ringing and maintain high resonant frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional optical correction methods are used to correct scan line errors, then correction capability is achieved, but system cost and complexity increase significantly
Solution Approach 1:
The patent replaces complex optical correction systems with a piezoelectrically actuated mirror system. The piezoelectric bimorph actuator uses electrical signals to directly control mirror deflection, substituting mechanical optical adjustment mechanisms with an electromechanical system that achieves the same correction function with reduced complexity and lower cost.
Solution Approach 2:
The patent changes the physical state and properties of the mirror system by using piezoelectric materials that can dynamically alter their shape in response to electrical signals. This allows real-time adjustment of scan line position, bow, and skew by changing the mechanical parameters of the mirror through electrical actuation, providing precise control without complex mechanical systems.
2Productivity
If piezoelectric actuators with high resonant frequency are used, then real-time correction capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs a dynamic mirror mounting system where the piezoelectric bimorph actuator can be precisely controlled during operation. The system uses feedback control and adaptive algorithms that adjust the actuator commands based on real-time measurements, allowing high resonant frequency operation without requiring ultra-precise static mounting tolerances. The dynamic control compensates for manufacturing variations.
Solution Approach 2:
The patent incorporates feedback mechanisms that measure the actual mirror position and scan line characteristics, comparing them against desired values. This feedback loop allows the system to compensate for manufacturing precision variations by continuously adjusting the piezoelectric actuator commands, enabling high resonant frequency correction while tolerating normal manufacturing tolerances.
3Adaptability or versatility
If multiple ROS systems are integrated for wider formats, then printing capability is extended, but alignment precision between systems deteriorates
Solution Approach 1:
The patent creates a universal correction system that can be applied to multiple ROS systems with the same piezoelectric mirror assembly. The standardized interface and control algorithms allow different ROS systems to be seamlessly integrated and aligned, as each system uses the same correction mechanism. This multi-functionality approach enables wider format printing by combining multiple ROS systems while maintaining alignment precision through standardized alignment procedures.
Solution Approach 2:
The patent employs preliminary alignment procedures where the piezoelectric mirror system is calibrated and aligned before being integrated into the multi-ROS system. By performing alignment adjustments in advance and establishing reference parameters during initial setup, the system achieves precise inter-system alignment that is maintained during operation, enabling reliable integration of multiple ROS systems for extended printing formats.
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 agile beam steering mirror system effectively corrects scan line position errors in real-time, improving print quality, enabling seamless integration of multiple ROS systems and extending ROS-based printing to wider formats without significant cost or complexity increases.
Implementation Method 1
a cantilevered piezoelectric bimorph actuator
Implementation Method 2
capacitive sensing and air damping
Implementation Method 3
capacitive sensing and air damping to reduce ringing
Data Source
AI summary
Scan line position error resulting in banding, bow, skew, etc. is corrected by way of an agile beam steering mirror assembly in a ROS printing system and the like. The agile beam steering mirror system comprises a piezoelectric bending actuator fixedly mounted to a substrate at a proximate end thereof. A mirror structure is mounted at a free distal end of the bending actuator. Voltage applied to the bending actuator causes rotation of the mirror to thereby correct for positional errors of the scan line. Correction waveforms may be stored in control memory associated with the agile beam steering mirror assembly. A capacitive sensing circuit using a sensing electrode located beneath the free end of the bending actuator may be used in a feedback arrangement to determine and control mirror position.