Imaging Sensor Assembly for Nozzle Trajectory Measurement
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Solution Overview
Problem
Printers, such as inkjet printers, face challenges in efficiently testing the trajectory accuracy of a large number of nozzles, leading to potential defects in printed output due to nozzle trajectory errors, which are difficult and costly to diagnose using existing methods.
Innovation Solution
An imaging sensor assembly with two-dimensional planar imaging sensors and a skip pattern algorithm that simultaneously images drops from multiple nozzles, allowing for rapid and cost-effective measurement of nozzle health by calculating trajectory errors across all nozzles in a single pass, utilizing a CMOS sensor with two parallel rows of pixels and a lens system for multiplexing and multichannel operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used to test nozzle trajectory accuracy, then measurement precision can be maintained, but testing time and cost increase significantly
Solution Approach 1:
The patent segments the testing process by dividing the nozzle array into multiple zones that can be tested simultaneously using multiple imaging sensors. Each sensor captures trajectory data from a specific zone, allowing parallel processing and reducing total testing time while maintaining measurement precision for each individual nozzle.
Solution Approach 2:
The patent transitions from traditional single-point trajectory measurement to two-dimensional planar imaging measurement. By capturing the entire drop trajectory in a 2D plane simultaneously, the system measures multiple nozzles' trajectories in parallel, dramatically reducing testing time while preserving measurement accuracy through image processing algorithms.
2Measurement precision
If traditional single-nozzle testing methods are used, then measurement accuracy is maintained, but device complexity and testing cost increase
Solution Approach 1:
The patent merges multiple measurement functions into a single integrated imaging sensor system. The two-dimensional planar imaging sensor simultaneously captures trajectory information from multiple nozzles, combining what would traditionally require multiple separate measurement devices into one unified system, thereby reducing overall device complexity while maintaining measurement accuracy.
Solution Approach 2:
The patent uses optical imaging to create a visual copy of the drop trajectories, replacing complex mechanical measurement apparatus. The imaging sensor captures light reflected from or transmitted through the droplets, creating optical copies of their paths that can be analyzed digitally, simplifying the physical measurement system while preserving measurement precision.
3Reliability
If comprehensive nozzle testing is performed, then print quality is improved, but testing cost increases
Solution Approach 1:
The patent implements a self-testing capability where the printer's own imaging sensors and processing systems are used to diagnose nozzle trajectory issues. This eliminates the need for external, expensive specialized testing equipment, reducing manufacturing costs while enabling comprehensive nozzle testing to ensure print quality.
Solution Approach 2:
The patent replaces complex mechanical trajectory measurement systems with optical imaging and digital image processing. This substitution dramatically reduces the cost of the testing system while enabling comprehensive testing of all nozzles, thereby improving print quality through more thorough nozzle health assessment without proportionally increasing system cost.
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 approach significantly reduces the time and cost of nozzle health testing, enabling fast and accurate measurement of nozzle trajectory errors, improving print quality by identifying and addressing issues up to 40 to 60 times faster than traditional methods.
Implementation Method 1
light redirected by liquid droplets ejected from nozzles
Implementation Method 2
images of in-flight drops ejected from nozzles
Implementation Method 3
a lens and sensed to detect a vertical trajectory
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A sensor images drops ejected from a printhead nozzle. The sensor has two parallel spaced-apart rows of imaging pixels. In one example, a lens projects an image of a drop ejected from a printhead onto the rows sequentially as the drop travels along a trajectory.