Single Camera Can Interior Imaging via Conical Mirror
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Solution Overview
Problem
Current machine vision systems for inspecting the interior of beverage cans face challenges in capturing high-quality images of the entire interior surface using a single camera, due to the cylindrical geometry and opaque nature of the cans, leading to increased complexity and cost.
Innovation Solution
A system comprising a cylindrical illuminator, a truncated conical mirror, and a single camera positioned to capture a single image of the interior surface, with the illuminator and mirror aligned to reflect light from the interior surface to the camera, allowing for comprehensive imaging of the can's interior without the need for multiple cameras or complex setups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single camera is used to image the interior of beverage cans, then the system complexity and cost are reduced, but the ability to capture the entire interior surface with sharp focus is compromised due to the limited field-of-view and depth of focus
Solution Approach 1:
A cylindrical mirror is introduced as an intermediary optical element between the can interior and the camera. The mirror reflects light from different regions of the can interior (including the neck and body) onto the camera sensor, enabling a single camera to capture the entire interior surface that would otherwise be inaccessible or out of focus.
Solution Approach 2:
The system transitions from direct axial imaging to oblique reflection imaging by positioning the camera at an angle relative to the can axis. The cylindrical mirror facilitates this dimensional change, allowing the camera to capture light rays from multiple spatial dimensions (neck, body, and bottom regions) simultaneously on a two-dimensional sensor plane.
2Manufacturing precision
If multiple cameras are used to capture the entire interior surface, then image quality and coverage are improved, but system complexity and cost increase
Solution Approach 1:
The optical paths from multiple potential camera positions are merged into a single camera system through the use of the cylindrical mirror. The mirror combines light rays from the neck region, body region, and bottom region into a single reflected image that falls onto one camera sensor, eliminating the need for multiple separate cameras.
Solution Approach 2:
The cylindrical mirror serves multiple functions simultaneously: it acts as a reflector for the neck region, a field-of-view expander for the body region, and a light guide for the bottom region. This multi-functional optical element replaces what would traditionally require multiple dedicated camera systems.
3Measurement precision
If the camera is positioned to capture the neck region, then detailed imaging of the neck is achieved, but the body and bottom regions become out of focus or out of frame
Solution Approach 1:
The system uses oblique reflection geometry to map three-dimensional spatial regions (neck, body, bottom) onto the two-dimensional camera sensor plane. The cylindrical mirror creates a coordinate transformation that allows detailed neck imaging while simultaneously capturing the full extent of the body and bottom regions through reflected light paths.
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 configuration enables efficient and cost-effective imaging of the entire interior surface of cylindrical objects, including beverage cans, allowing for real-time defect detection and minimizing maintenance complexity, even at high production speeds.
Implementation Method 1
A cylindrical illuminator, positioned substantially to one side of an opening of the cylindrical object to be imaged, to illuminate at least a portion of the interior surface of the cylindrical object
Implementation Method 2
a truncated conical mirror positioned substantially within the cylindrical illuminator to reflect an image of at least a portion of the interior surface of the cylindrical object
Data Source
AI summary
A system and method for imaging an interior of a substantially cylindrical object are disclosed. In accordance with an embodiment of the present invention, a substantially cylindrical illuminator is positioned above an opening of a substantially cylindrical object to be imaged (e.g., a beverage can) in order to illuminate at least a portion of the interior surface of the object. A truncated conical mirror is positioned within an interior space of the illuminator to reflect an image of at least a portion of the interior surface of the object. A single camera is positioned above the illuminator and mirror to capture a single image of at least the interior surface of the object via light reflected directly from at least a portion of the interior surface of the object to the camera and from the mirror to the camera. The entire interior surface of the object is captured in the single image which may be analyzed for defects.