Multi-shot Illumination Control for Optical Inspection
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Solution Overview
Problem
Optical inspection machines for quality control require multiple stations to achieve high accuracy, leading to increased machine size and inspection cycle time, and existing methods to reduce stations result in unacceptable loss of image resolution.
Innovation Solution
A method using a controllable digital video camera and a programmable illuminator with multiple illumination sources, activated in synchronization with camera shots to achieve high-resolution images without filtering, allowing for precise dimensional checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple inspection stations are used to acquire various images of the part, then measurement precision is improved, but device complexity and inspection cycle time increase
Solution Approach 1:
The patent applies periodic action by using a single inspection station that captures multiple images of the part at different rotational positions during one inspection cycle. The rotary table rotates the part through multiple positions (e.g., 0°, 90°, 180°, 270°) and the camera captures images at each position, replacing the need for multiple stationary inspection stations while maintaining comprehensive coverage for quality control.
Solution Approach 2:
The patent implements dynamics by introducing rotational movement to the inspection system. Instead of having multiple fixed inspection stations, a single inspection station inspects a rotating part at multiple dynamic positions. This transforms the static multi-station configuration into a dynamic single-station system that achieves the same inspection coverage through motion.
2Measurement precision
If multiple inspection stations are used to acquire various images of the part, then measurement precision is improved, but inspection cycle time increases
Solution Approach 1:
The patent uses periodic action by capturing multiple images at different rotational positions during a single continuous inspection cycle. The rotary table rotates the part through multiple positions while the camera periodically captures images at each position, enabling comprehensive inspection in one pass rather than requiring sequential processing at multiple stations.
Solution Approach 2:
The patent maintains continuity of useful action by performing all inspection operations in a single continuous rotation cycle. The part rotates continuously through multiple positions while the inspection station continuously captures images, eliminating the stop-and-go nature of multiple discrete inspection stations and reducing total inspection time.
3Measurement precision
If image filtering operations are performed to emphasize specific surfaces, then measurement focus is improved, but image resolution is lost
Solution Approach 1:
The patent applies local quality by using multiple illumination sources with different color temperatures (e.g., cold white, warm white, red, green, blue LEDs) to selectively highlight different surface features. Each illumination source provides localized quality enhancement for specific surface characteristics, allowing the system to emphasize different surfaces without applying lossy filtering operations to the entire image.
Solution Approach 2:
The patent implements parameter changes by varying the color temperature and spectral characteristics of illumination sources to achieve different surface emphasis effects. Instead of filtering image data and losing resolution, the system changes the illumination parameters (color temperature, wavelength) to naturally enhance specific surface features in the captured images, preserving full image resolution.
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
Reduces the number of inspection stations and cycle time while maintaining high image resolution, ensuring accurate dimensional measurements.
Implementation Method 1
illuminator (12) provided with a plurality of illumination sources (16) arranged to illuminate various portions of the part or to illuminate the part from different angles
Implementation Method 2
controllable digital video camera (10) framed shots of the part with different lighting conditions
Data Source
AI summary
A method for acquiring images of a part to be inspected comprises the following steps framing the part with a digital video camera providing an illuminator comprising a plurality of illumination sources arranged to illuminate various portions of the part or to illuminate the part from different angles, wherein individual illumination sources or groups of illumination sources are controlled individually by means of an illumination control unit operationally connected to the digital video camera; controlling the video camera to take a series of shots of framed part, with each shot being defined by a preset exposure time with each shot and for the duration of the exposure time generating a part illumination condition through the illumination control unit by activating a portion of the individual illumination sources or groups of illumination sources so the sequence of shots is taken with different corresponding lighting conditions according to a preset lighting program.