Mirror System for Uniform Container Inspection
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Solution Overview
Problem
Existing optical inspection systems for containers suffer from complex designs, limited apertures, and high costs due to the use of lenses, which lead to image aberrations, uneven illumination, and visibility of contaminants, especially when inspecting moving containers with or without liquids.
Innovation Solution
A device using a mirror system with a concave mirror to project a planar light pattern onto the entrance pupil of a recording device, allowing for compact design, uniform illumination, and effective inspection of containers with or without liquids, while avoiding chromatic aberration and visibility of contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If lens collimators are used for illumination, then the container can be illuminated, but image aberrations occur and the design becomes complex requiring beam path folding
Solution Approach 1:
The patent replaces the lens-based optical system with a mirror-based system. Specifically, it uses a reflective element (mirror or prismatic structure) to redirect and uniformize the light path instead of using refractive lenses. This substitution eliminates chromatic aberrations and reduces the need for complex beam path folding while achieving uniform illumination of the container.
2Illumination intensity
If lens collimators are used, then illumination can be achieved, but the maximum aperture is limited which impacts uniform illumination of moving containers
Solution Approach 1:
The patent employs a reflective optical system with mirrors or prismatic elements that can redirect light from a compact light source across a larger field of view. This allows the system to achieve large effective aperture and uniform illumination of moving containers without being limited by the physical size of a single lens element, while maintaining a compact overall device structure.
3Measurement precision
If complex optics are used to account for liquid effects, then accurate inspection results can be achieved, but the system becomes costly and complex
Solution Approach 1:
The patent uses a simple reflective element (mirror or prism) instead of complex multi-element optical systems to handle liquid effects. The reflective geometry is designed to compensate for refraction and reflection effects at the liquid-container interfaces, providing accurate inspection of liquid-filled containers without requiring expensive and complex optical corrections.
4Device complexity
If a point-like light source is used, then the device can be simple, but the illumination of moving containers at multiple positions becomes non-uniform
Solution Approach 1:
The patent transforms the illumination from a point-like source to a planar light distribution by using a reflective element that spreads the light across a two-dimensional area. This planar illumination geometry ensures uniform lighting across the entire field of view, enabling consistent inspection of moving containers at multiple positions without requiring a complex array of light sources.
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
The mirror system ensures consistent lighting conditions across the image field, effectively illuminates containers from multiple directions, and detects defects without visible aberrations or contaminants, providing accurate inspection results with reduced costs and complexity.
Implementation Method 1
a mirror system is further provided, arranged in the beam path between the illumination unit and the container, which comprises at least one concave mirror. The mirror system projects the light pattern generated by the illumination unit onto the plane of the entrance pupil of the recording device.
Implementation Method 2
The mirror system is designed (i.e., in a single-mirror system, the mirror surface of the single concave mirror is shaped) so that the plane of the light pattern generated by the luminous surface (= object plane) is imaged onto the plane of the entrance pupil of the recording device, thus acting as a collimator.
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a device (10) for the optical inspection of an empty or liquid-filled container (1) comprising a lighting unit (12) and a recording device (camera 14). The lighting unit includes a luminous surface by means of which a planar light pattern consisting of at least two areas of different light intensities can be generated, and the container can be illuminated with light of the light pattern (e.g., dark-field or bright-field illumination), in particular, can be transilluminated. According to the invention, a mirror system (20) is also provided in the beam path between the lighting unit and the container, which comprises at least one concave mirror (e.g., an elliptical mirror). The mirror system projects the light pattern generated by the lighting unit onto the plane of the entrance pupil of the recording device.