Plane-Mirror Inspection of Injection-Molded Parts Without Optical Distortion
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Solution Overview
Problem
Existing inspection systems for injection-molded parts suffer from optical distortions using concave mirrors, leading to unreliable detection of defects like burrs, irregularities, and insufficiently injected areas, and are not suitable for high-speed automated production lines due to limited inspection times and complex designs.
Innovation Solution
An inspection system utilizing an optical system that generates undistorted shadow images of workpieces through plane mirrors, allowing for high-contrast detection of defects with minimal distortion, enabling reliable inspection even at high production speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a concave mirror arrangement is used to record workpiece images, then the workpiece can be inspected as it passes through the inspection device, but the mirror image generates strong optical distortions that reduce inspection reliability
Solution Approach 1:
The patent extracts the problematic concave mirror element from the optical system and replaces it with plane mirrors. This removes the source of optical distortion while maintaining the ability to capture images of moving workpieces. The plane mirrors reflect light without introducing the curvature-induced distortions that plagued the previous concave mirror design.
Solution Approach 2:
The patent creates an undistorted optical copy of the workpiece using plane mirrors and camera system. Instead of relying on the distorted mirror image, the system produces a faithful geometric reproduction of the workpiece features, enabling accurate measurement and defect detection while the workpiece moves through the inspection device.
2Reliability
If complex optical systems are used to achieve high inspection accuracy, then defect detection reliability improves, but the system becomes more expensive and complex
Solution Approach 1:
The patent segments the optical system into simple, discrete plane mirror elements rather than using a complex integrated optical train. Each plane mirror performs a specific reflection function, and the system achieves high reliability through the coordinated action of these simple, well-defined components rather than through complex optical interactions.
Solution Approach 2:
The patent replaces expensive, complex optical components with inexpensive plane mirrors and a standard camera system. The simple plane mirrors are cheap to manufacture and replace, and the overall system achieves high reliability through this economical approach rather than through expensive specialized optics.
3Productivity
If the inspection system is designed for high-speed production lines, then productivity increases, but the inspection time per workpiece decreases making accurate detection difficult
Solution Approach 1:
The patent positions the plane mirrors and camera system so that the optical path is pre-configured for the expected workpiece motion. The lighting and optical geometry are arranged in advance to capture clear images during the brief moment the workpiece passes through the inspection zone, enabling accurate detection even at high speeds without requiring extended inspection time.
4Area of stationary object
If compact inspection systems are used for close-spaced workpieces, then space utilization improves, but the optical system becomes more difficult to design and implement
Solution Approach 1:
The patent uses plane mirrors to redirect light paths in three-dimensional space, allowing the optical components to be arranged in a compact configuration. The mirrors fold the optical path and enable the camera and lighting to be positioned optimally within a limited space, accommodating close-spaced workpieces without requiring a linear expansion of the optical system.
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 system provides reliable detection of defects with high image sharpness and short inspection times, suitable for automated production lines, reducing equipment complexity and cost while maintaining production speed.
Implementation Method 1
an optical system which, when the workpiece is radiated with the light source of the illumination means, generates a shadow image of the workpiece
Implementation Method 2
An inspection system utilizing an optical system that generates undistorted shadow images of workpieces through plane mirrors
Data Source
AI summary
The invention relates to an inspection system for checking elongate workpieces (2), more particularly injection-moulded parts such as pipette tips, which have a workpiece longitudinal axis, comprising: (i) a holding device (3) for holding a plurality of workpieces to be checked, which are arranged on the holder preferably in a plurality of rows (R1, R2) separated from one another by a distance d, (ii) an illumination device (4) comprising at least one light source (4a), (iii) an optical detection means (6), the workpiece being arranged in the beam path (S1, S2) of the light emitted from the light source between the light source and the optical detection means, and the optical detection means detecting the image of the workpiece generated by the illumination device, (iv) an optical system (5) for orienting the light emitted from the light source preferably laterally towards the workpiece to be checked arranged on the holder, and from the workpiece towards the optical detection means, (v) preferably an evaluation device (7), which is connected in a signal-transmitting manner to the optical detection means and permits an evaluation of the workpiece image. The optical system is designed to generate a preferably non-distorted shadow image of the workpiece from at least one direction transverse to the workpiece longitudinal axis and to project the shadow image preferably in non-distorted fashion onto the detection means.