Event-Based Imaging for Defects on Moving Homogeneous Surfaces
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Solution Overview
Problem
Conventional image sensors struggle to capture defects on a homogeneous surface of a moving object due to motion blur, requiring high recording frequencies that compromise exposure times, while line scan cameras offer limited views and short exposure times, and event-based cameras fail to effectively associate events with defects.
Innovation Solution
An event-based image sensor records a dataset of events, compensating for object movement by calculating back to a reference point in time, allowing for precise defect detection on moving objects by generating images that approximate a stationary view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional image sensors are used to capture defects on moving objects, then recording frequency can be increased, but exposure time decreases causing motion blur that prevents defect detection
Solution Approach 1:
The patent replaces the conventional mechanical/image sensor exposure system with an event-based camera system that detects intensity changes asynchronously. Instead of using fixed exposure times that cause motion blur, the system uses event pixels that trigger on intensity changes, allowing defect detection on moving objects without the traditional exposure-time limitation.
Solution Approach 2:
The patent changes the fundamental parameter from fixed exposure time to variable event-triggered timing. Each pixel operates independently and triggers an event when intensity changes exceed a threshold, allowing the system to capture defects at any moment during object movement without being constrained by a fixed exposure window.
2Measurement precision
If line scan cameras are used to achieve high recording frequencies, then motion blur is reduced, but field of view becomes extremely limited
Solution Approach 1:
The patent divides the image sensor into multiple independent event pixels that operate autonomously. Each pixel independently detects intensity changes and generates events, allowing the entire field of view to be monitored simultaneously without the mechanical scanning limitation of line scan cameras.
Solution Approach 2:
The patent introduces dynamic, asynchronous operation where each pixel independently triggers on intensity changes rather than following a fixed scanning sequence. This allows the system to adapt to object movement dynamically while maintaining a wide field of view, unlike the static scanning approach of line scan cameras.
3Speed
If event-based cameras are used to capture fast-moving objects, then response time to intensity changes is improved, but events become scattered and cannot be associated with specific defects
Solution Approach 1:
The patent implements feedback through a control unit that receives events from multiple pixels and uses temporal and spatial correlation to associate scattered events with specific defects. The control unit analyzes the timing and position of events to reconstruct defect information, converting the scattered event data into meaningful defect detection results.
Solution Approach 2:
The patent adds the time dimension to the spatial distribution of events by using precise time stamps for each event. This allows the control unit to correlate events that occur at different times and positions, reconstructing the spatial pattern of defects from the temporal sequence of scattered events.
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 method enables the detection of even small defects on fast-moving objects with continuous data recording and precise time stamps, enhancing defect recognition accuracy and reducing noise interference.
Implementation Method 1
An event-based or neuromorphological image sensor has a plurality of pixel elements... Each pixel element individually checks for itself whether it has determined a change in intensity... Each pixel is individually checking whether a change in the intensity has occurred and respectively triggers an event exactly then
Data Source
AI summary
A method for recognizing defects on a homogeneous surface of an object during a movement of the object is provided, wherein an image of the homogeneous surface is recorded and the image is evaluated as to whether it has defects. In this respect, the image is recorded by an event-based image sensor that detects events of a changing intensity with a plurality of pixel elements; the recording takes place over a time interval within which the homogeneous surface moves on over at least some pixel elements of the image sensor; the events are corrected in accordance with a time that has elapsed since a reference point in time and the movement that has taken place during the elapsed time; and the corrected events are collected in an image that is then evaluated with respect to the defects.