Encoder Strip Expansion Compensation in Inkjet Printers
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Solution Overview
Problem
Inkjet printing systems face print defects due to environmental changes such as temperature and humidity variations, which cause encoder strip expansion, leading to misalignment of print carriages and dot placement errors.
Innovation Solution
The system measures phase differences in signals from encoders on each print carriage as they move along an encoder strip, determining a measured unit change to adjust the printing process and prevent defects by compensating for the expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If environmental changes (temperature and humidity) occur during printing, then the encoder strip expands, but this causes misalignment of print carriages and dot placement errors
Solution Approach 1:
The system continuously monitors the position of print carriages using encoders that read markings on the encoder strip, detects deviations caused by thermal expansion, and provides feedback signals to the control system. The control system then adjusts the carriage positions in real-time to compensate for the expansion, maintaining accurate alignment despite environmental changes.
Solution Approach 2:
The system measures the physical expansion of the encoder strip by detecting changes in the spacing between encoder markings using multiple encoders. By quantifying the expansion parameter and using it to calculate correction factors, the system adjusts carriage positioning to compensate for the dimensional changes in the encoder strip.
2Manufacturing precision
If alignment markings are used to correct for encoder strip expansion, then carriage alignment can be maintained, but the printing process becomes more complex and time-consuming
Solution Approach 1:
The system replaces the mechanical alignment marking method with an optical/electronic detection system. Instead of physically marking alignment positions on the encoder strip, the system uses optical encoders to detect the positions of encoder markings and electronically processes the position data to determine expansion and calculate corrections, eliminating the need for physical alignment markings.
Solution Approach 2:
The system creates a digital copy of the encoder strip position information by using multiple encoders to read the encoder markings and generate electrical signals representing the physical positions. This digital representation is then processed to detect expansion and calculate correction factors, replacing the need for physical alignment markings with an electronic information copy.
3Manufacturing precision
If alignment markings are printed on the medium to compensate for expansion, then dot placement accuracy can be maintained, but the printing speed decreases due to additional processing steps
Solution Approach 1:
The system performs preliminary detection of encoder strip expansion using multiple encoders before the printing process begins. By measuring the spacing between encoder markings and calculating the expansion factor in advance, the system pre-computes the correction factors that will be applied to carriage positioning during printing, eliminating the need for real-time adjustments and alignment marking operations during the printing process.
Solution Approach 2:
The system replaces the mechanical process of printing alignment markings on the medium with an electronic detection and calculation system. Instead of physically marking the print medium with alignment references, the system uses optical encoders to detect encoder strip positions, electronically calculates expansion corrections, and applies these corrections to carriage positioning commands, maintaining dot placement accuracy without adding physical marking steps to the printing process.
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 method effectively prevents print defects by accurately aligning print carriages, ensuring consistent image reproduction despite environmental changes, without the need for alignment markings and reducing noise effects.
Implementation Method 1
The encoder may be an optical encoder that generates a signal based on the reflection or transmission of light off of or through the encoder strip
Data Source
AI summary
A system is provided that includes an encoder strip having encoder markings, first and second optical encoders positioned at a fixed distance from one another on a substrate and, responsive to being moved along the encoder strip, configured to generate first and second signals, respectively, that each indicate detection of the encoder markings on the encoder strip and processing circuitry configured to determine a current phase difference between the first and the second signals using a first portion of the first signal that corresponds to a first plurality of encoder markings and a second portion of the second signal that corresponds to a second plurality of encoder markings.