Container Inspection Illumination Using Beam Splitter and Diffuser
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Solution Overview
Problem
Existing methods for inspecting containers with metallic inner walls face challenges such as unwanted reflections and bright spots in camera images due to oblique illumination, which complicates the detection of irregularities and contaminants, especially when dealing with shiny surfaces.
Innovation Solution
An apparatus and method where the illumination device is positioned between the monitoring device and the object, using diffuse illumination and a flat diffusing element to prevent reflections, with the illumination device arranged close to the object to maximize light entry and minimize blurring, and a transport device to move objects along a predetermined path for efficient inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If oblique illumination is used from the background of the objective, then direct light entry into the monitoring device is prevented, but unwanted reflections occur on metallic internal surfaces
Solution Approach 1:
A beam splitter is introduced as an intermediary component between the illumination device and the monitoring device. The beam splitter directs illumination light onto the object while allowing reflected light to reach the monitoring device, thereby preventing direct light entry into the monitoring device while avoiding unwanted reflections on metallic surfaces.
Solution Approach 2:
The illumination device is positioned in a different spatial dimension (laterally adjacent to the optical axis) rather than directly in the optical path. This dimensional change allows illumination to occur without direct light entry into the monitoring device and without creating reflective hotspots on the inspected surfaces.
2Manufacturing precision
If small aperture openings are used to achieve sufficient depth of field, then depth of field is improved, but light intensity is reduced
Solution Approach 1:
The aperture opening is optimized in advance to balance depth of field requirements with light intensity needs. By performing preliminary optimization of the aperture settings before actual inspection, the system achieves sufficient depth of field for accurate inspection while maintaining adequate light intensity for high-speed imaging.
3Illumination intensity
If irradiation time is increased to compensate for light loss, then light intensity is improved, but blurring increases due to container movement
Solution Approach 1:
The system uses periodic action by synchronizing the illumination device with the high-speed camera shutter. Both are triggered at precisely controlled intervals to capture images during brief illumination periods, achieving sufficient light intensity while maintaining image clarity through synchronized periodic operation rather than continuous illumination.
Solution Approach 2:
The high-speed camera operates continuously at very short exposure times (less than 500 μs, preferably less than 20 μs), maintaining continuous useful action by capturing images at such high rates that motion blur is minimized. This continuous high-speed operation allows for sufficient light capture without increasing individual exposure time, thereby preventing blurring from container movement.
4Productivity
If high transport speeds are used to increase productivity, then productivity is improved, but available inspection time is reduced
Solution Approach 1:
The system replaces mechanical inspection methods with optical and electronic systems. High-speed cameras and electronic image processing enable rapid inspection at transport speeds of 120,000-140,000 containers per hour, substituting mechanical measurement and analysis with light-based detection that occurs virtually instantaneously, thereby maintaining productivity while minimizing inspection time.
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 allows for effective inspection of container interiors with reduced reflections, increased light intensity, and minimal blurring, enabling the capture of high-quality images even at high speeds, thus simplifying the inspection process.
Implementation Method 1
an illumination device (6) which illuminates at least one region of the inner wall (10b)
Implementation Method 2
using diffuse illumination and a flat diffusing element to prevent reflections
Data Source
AI summary
A device for inspecting containers which have an opening includes a transport device which transports the objects along a configured transport path. The device includes a monitoring device which is configured to monitor at least one region of an inner wall of the container through the opening. The monitoring device is configured to capture spatially resolved images, and has a lighting device configured to illuminate at least one region of the inner wall, is arranged between the monitoring device and the container.