Camera Diaphragm Control for Dynamic Depth of Field
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Solution Overview
Problem
Conventional camera systems in industrial applications, such as those installed above conveyor belts, face challenges in dynamically adjusting the aperture to ensure optimal image quality and depth of field for varying object distances and types, particularly when reading codes like barcodes and 2D codes, leading to suboptimal image data quality and decoding efficiency.
Innovation Solution
A camera system with an adjustable diaphragm controlled by a control and evaluation unit, which dynamically sets the aperture based on object distance and type, ensuring the object is recorded within a suitable depth of field range for effective image data capture and code reading, using a distance sensor and potentially combining distance and brightness measurements for precise diaphragm control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant aperture is used in the camera, then the device complexity is reduced, but the image quality and depth of field adaptability deteriorate
Solution Approach 1:
The patent implements a dynamic diaphragm control system where the aperture is continuously adjusted based on real-time distance sensor measurements. The control unit receives distance information and automatically modifies the diaphragm opening to optimize depth of field for objects at varying distances on the conveyor belt, transforming a static system into an adaptive dynamic one.
Solution Approach 2:
The system establishes a feedback loop where distance sensor data feeds into the control unit, which then adjusts the diaphragm setting accordingly. This closed-loop control ensures the aperture always matches the current object distance, maintaining optimal image quality without manual intervention.
2Area of stationary object
If multiple cameras are installed to cover larger conveyor belt width, then the detection coverage is improved, but the device complexity and cost increase
Solution Approach 1:
Instead of expanding coverage horizontally by adding more cameras side-by-side, the patent enhances the system's capability in the depth dimension through dynamic aperture control. A single camera with adaptive diaphragm settings can effectively handle objects at various distances across the conveyor belt, providing multi-focal-plane coverage that reduces the need for multiple camera units.
3Measurement precision
If the aperture is adjusted for each object, then the image quality and decoding accuracy are improved, but the processing time and control complexity increase
Solution Approach 1:
The system performs preliminary distance measurement using the distance sensor before the actual image capture. This advance measurement allows the control unit to pre-adjust the diaphragm setting, ensuring optimal aperture is ready before the object enters the critical detection zone, eliminating any potential time loss during the imaging process.
Solution Approach 2:
The patent replaces manual or mechanical aperture adjustment with an electronically controlled diaphragm system driven by automated control logic. This substitution enables rapid, precise aperture changes based on electronic distance signals, significantly reducing adjustment time compared to mechanical systems while maintaining high decoding accuracy.
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 enhances image data quality by adapting the diaphragm settings per object, allowing for simpler optics design and achieving high decoding rates by ensuring images are sharp enough for accurate code reading, even under varying conditions.
Implementation Method 1
A distance sensor that is based on a time of flight (TOF) process is integrated in a camera
Data Source
AI summary
A camera (10) is provided for the detection of objects (48) moved through a detection zone that has an image sensor (18) for recording image data, a reception optics (16) having an adjustable diaphragm (17), and a control and evaluation unit (38) to read the image data and to set the diaphragm (17), In this respect, the control and evaluation unit (38) is furthermore configured to set the diaphragm (17) per object (48) such that the object (48) is recorded in a depth of field range.