Strobe Illumination Timing Control for Machine Vision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Precision machine vision inspection systems face challenges in accurately detecting edges due to sub-optimal illumination, leading to reduced measurement repeatability and increased blurring during high-speed image capture, particularly with powerful LED strobe sources that introduce noise and periodic ripple components.
Innovation Solution
The implementation of a control system that synchronizes the timing of the camera integration period with the illumination pulse duration, using a timing overlap to avoid initial noise periods and periodic ripple components, allowing for more repeatable image exposure levels and increased dynamic range, even at short exposure times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If powerful LED strobe sources are used to illuminate the workpiece during high-speed image capture, then the illumination intensity is improved, but noise and periodic ripple components are introduced that reduce measurement repeatability
Solution Approach 1:
The control system initiates the illumination pulse before the camera exposure begins, allowing the LED strobe to reach its stable operating state before image capture. This preliminary action ensures that the illumination is already at peak intensity and free from startup noise and ripple components when the camera captures the image, thereby maintaining both high illumination intensity and measurement repeatability
Solution Approach 2:
A control system acts as an intermediary between the LED strobe source and the camera, coordinating their operation timing. The control system generates synchronized trigger signals that ensure the illumination pulse precedes the camera exposure, filtering out the harmful noise and ripple components while preserving the beneficial high-intensity illumination for accurate edge detection
2Illumination intensity
If the camera integration period is extended to capture sufficient light, then the image brightness is improved, but motion-induced blurring increases during high-speed workpiece transport
Solution Approach 1:
The system employs periodic pulsed illumination synchronized with the camera's frame rate and workpiece transport speed. By using short-duration illumination pulses at optimized intervals, the system captures sufficient light for bright images while keeping each exposure window brief enough to minimize motion blur, thereby maintaining both image brightness and edge detection accuracy
Solution Approach 2:
The control system dynamically adjusts the illumination pulse duration and timing parameters based on workpiece transport speed and camera settings. By optimizing these parameters, the system achieves the minimum exposure time required for sufficient image brightness while keeping the integration period short enough to prevent motion-induced blurring, thus resolving the contradiction between brightness and precision
3Illumination intensity
If the illumination pulse duration is extended to provide sufficient light for short exposure times, then the image brightness is improved, but the noise and ripple components from the LED strobe have more time to affect the image
Solution Approach 1:
The illumination pulse is initiated before the camera exposure begins, allowing the LED strobe to reach its stable operating state with minimal noise and ripple components. By timing the pulse to precede the exposure, the system ensures that the majority of the illumination energy is delivered during the stable phase, improving image brightness while minimizing the impact of transient noise and ripple
Solution Approach 2:
The system uses short, intense illumination pulses that rush through the critical exposure window quickly. By concentrating the illumination energy into a brief, high-intensity pulse that occurs during the stable operating phase of the LED strobe, the system achieves sufficient image brightness while minimizing the time during which noise and ripple components can affect the image
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 enhances the accuracy and repeatability of edge detection and autofocus operations by minimizing noise and ripple-induced variations, improving the dynamic range of exposures and maintaining high precision in precision machine vision inspection systems.
Implementation Method 1
The illumination source may emit light of one or more visible or invisible wavelengths of radiation that are suitable for imaging the workpiece, as a transient flash or pulse
Data Source
AI summary
The repeatability of strobe illumination for image exposure is improved over a wide dynamic range in a machine vision system wherein a relationship between a camera integration period and a pulse duration of a strobe light generator control the effective exposure of a camera image during a timing overlap between a beginning of the camera integration period and an end of the pulse duration. To avoid noise in the illumination, the illumination pulse duration may start, the camera integration period may begin after a delay relative to that start and not later than the end of the pulse duration, the pulse duration may end, and the camera integration period may end not earlier than the end of the pulse duration. The timing overlap may also be synchronized with a periodic ripple component in the strobe illumination, to provide improved repeatability.