Oblique Illumination Shadow Analysis for Ink Droplet Volume Measurement
Solution Overview
Problem
Current ink droplet volume measurement methods, such as the chromatic aberration method, face challenges in high-speed and large-quantity measurements, and are affected by substrate quality and positional relationships, leading to inaccurate results.
Innovation Solution
An ink droplet volume measurement apparatus utilizing oblique illumination, an imaging device, and a calculation device to analyze droplets and their shadows on a substrate, calculating volume using equations based on the angle of illumination, shadow length, and droplet radius, ensuring accurate and high-speed measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chromatic aberration method is used to measure ink droplet volume, then measurement can be performed, but measurement time is long and high-speed measurement is difficult
Solution Approach 1:
The patent replaces complex optical analysis methods (chromatic aberration) with a simpler geometric measurement approach using shadow length and droplet radius, enabling faster processing while maintaining measurement capability
Solution Approach 2:
The patent uses shadow imaging as a simplified copy or representation of the actual droplet, measuring the shadow's geometric properties (length and area) to infer droplet volume without directly analyzing the droplet's complex optical characteristics
2Productivity
If 2D-image area measurement method is used, then measurement can be performed, but measurement accuracy is affected by substrate quality and contact angle distribution
Solution Approach 1:
The patent introduces shadow length as an intermediary measurement that is independent of substrate properties. The shadow cast by oblique illumination provides a geometric reference that does not depend on contact angle or substrate quality, serving as a mediator between the droplet and measurement system
3Measurement precision
If 2D-image illumination reflection method is used, then droplet diameter can be measured, but measurement errors occur due to shift in positional relationship between illumination and droplets
Solution Approach 1:
The patent uses asymmetric oblique illumination at a specific angle (30-60 degrees) to create a shadow that extends in one direction. This asymmetric lighting geometry creates a stable, directional shadow that is less sensitive to positional variations compared to symmetric or normal illumination
Solution Approach 2:
The patent transitions from measuring only droplet diameter (2D circular measurement) to measuring shadow length in addition to droplet area, adding a new dimensional parameter that provides more robust volume calculation independent of illumination position
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 precise and rapid measurement of ink droplet volumes, ensuring stable print quality and high productivity in inkjet printing processes.
Implementation Method 1
an imaging device configured to obtain planar images of the droplets and a shadow of the droplets generated by the oblique illumination
Data Source
AI summary
An ink droplet volume measurement apparatus including an oblique illumination configured to emit light at a first angle to ink droplets deposited onto a substrate, an imaging device configured to obtain planar images of the ink droplets and a shadow of the ink droplets generated by the emitted light and a calculation device configured to calculate a volume of the ink droplets deposited onto the substrate based on the planar images of the ink droplets and the shadow of the ink droplets.