Optical Displacement Tracking With Dual Sensors for Printers
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Solution Overview
Problem
Conventional displacement tracking methods, such as relative and absolute tracking, suffer from accumulated errors and impracticality in applications like printing, where updating reference images is necessary due to overlapping portions decreasing, and adding codes or marks to substrates is costly and wasteful.
Innovation Solution
A system using a pair of optical sensors in fixed spatial relationship within a printer, comparing images generated by these sensors to track displacement accurately without marks or codes, employing image comparison algorithms and synchronization to ensure precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional relative displacement tracking using optical sensors is used, then displacement can be tracked, but accumulated errors occur and reference images need frequent updating
Solution Approach 1:
The patent uses a second optical sensor to capture a copy image of the substrate, which is then compared with the reference image from the first sensor. This optical copying approach eliminates the need for physical marks or codes on the substrate while maintaining tracking precision and avoiding accumulated errors through image correlation algorithms.
Solution Approach 2:
The patent replaces conventional mechanical encoder systems with an optical sensing system that uses image capture and correlation. This substitution eliminates mechanical contact, reduces wear, and provides non-contact displacement measurement with higher precision and no accumulated errors.
2Measurement precision
If codes or marks are added to substrates for tracking, then absolute displacement can be tracked, but manufacturing cost increases and waste is generated
Solution Approach 1:
The patent captures an optical copy (image) of the substrate surface using the second optical sensor and compares it with the reference image. This approach eliminates the need to physically add codes or marks to the substrate, thereby reducing manufacturing costs and avoiding waste from discarded marked substrates.
Solution Approach 2:
The patent extracts the tracking information directly from the optical image of the substrate surface features without requiring any additional marks or codes. The displacement is determined by correlating the positions of existing substrate features in the reference image and current image, eliminating the need for extra manufacturing steps.
3Measurement precision
If more pixels are placed along one axis of the optical sensor for coarse media tracking, then tracking accuracy improves, but sensor cost increases dramatically
Solution Approach 1:
The patent divides the tracking function between two optical sensors, each with moderate pixel counts. The first sensor captures the reference image and the second sensor captures the current image. This segmentation allows each sensor to use fewer pixels while achieving the same overall tracking accuracy through the comparison of the two images.
Solution Approach 2:
The patent transitions from single-axis tracking with high pixel density to two-axis tracking with moderate pixel density by using two sensors. The fixed spatial relationship between the two sensors along one axis and their complementary viewing angles provide tracking information in both axes without requiring excessive pixels in a single sensor.
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
Enables high-precision tracking of substrate displacement in printers, allowing precise ink deposition and cutting, and can be applied to multi-axis tracking in robotic vacuum cleaners and rotational displacement in mechanical elements.
Implementation Method 1
an optical sensor that generates images of the underlying surface
Data Source
AI summary
Introduced here is a system for optically tracking displacement with high precision across one or more axes. To track displacement of an object, images that are generated by a plurality of optical sensors can be compared against one another. For example, images that are generated by a first optical sensor can be compared against images that are generated by a second optical sensor. Because the first and second optical sensors are in a fixed spatial relationship with one another, displacement of the object can be established based on the degree to which a given image generated by the first optical sensor matches another image generated by the second optical sensor.