Robust Optical Aimer Triangulation for Autofocus Misalignment Correction
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Solution Overview
Problem
Existing autofocus systems in optical scanners face challenges due to mechanical misalignments and thermal deformations, leading to inaccurate triangulation and focus setting, particularly in complex scenes with multiple reflective surfaces.
Innovation Solution
The system employs multiple image-capture devices and aimer transmitters with fixed mechanical or optical characteristics, using divergent aimer beams to maintain consistent separation of aimer spots in captured images, allowing for automatic detection and correction of misalignments through triangulation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If active autofocus techniques using triangulation are used, then focusing speed is improved, but measurement precision deteriorates due to misalignment errors and loss of calibration
Solution Approach 1:
The system captures images of a known reference target and automatically detects positional deviations of aimer spots from expected locations. This feedback mechanism identifies misalignments caused by thermal or mechanical stresses and enables real-time correction of triangulation calculations, maintaining measurement precision while preserving the fast focusing speed of active autofocus.
Solution Approach 2:
The system dynamically adjusts triangulation calculation parameters based on detected misalignment conditions. By changing the reference frame or calibration parameters according to the detected deviation state, the system compensates for thermal expansion or mechanical deformation effects, maintaining accurate distance measurements despite environmental variations.
2Reliability
If multiple image sensors at fixed distance are used for triangulation, then reliability is improved, but device complexity increases
Solution Approach 1:
The system uses a single image sensor to capture multiple aimer spots from different transmitters, creating virtual multiple-sensor functionality through image processing. This approach achieves the reliability benefits of multiple sensors while avoiding the mechanical complexity and alignment issues of physically mounting multiple sensors at precise fixed distances.
Solution Approach 2:
The system replaces the mechanical solution of mounting multiple physical sensors at fixed distances with an optical and computational approach. By using multiple aimer transmitters and processing their spots in a single sensor's image, the system achieves triangulation reliability without the mechanical complexity of precision mounting and alignment.
3Manufacturing precision
If mechanical or thermal stresses occur, then manufacturing precision is maintained during production, but stability of the object's composition deteriorates due to warping or deformation
Solution Approach 1:
The system performs preliminary capture of an image containing a known reference target to establish baseline positions of aimer spots before normal operation. This preliminary action creates a reference framework that accounts for any existing misalignments, allowing the system to compensate for thermal or mechanical stresses that occur during operation and maintain stability despite environmental changes.
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 the accuracy and speed of autofocus by compensating for mechanical or thermal-induced misalignments, improving focus setting and distance estimation in various environments.
Implementation Method 1
senses a reflection of the emitted signal from the target's surface
Implementation Method 2
capturing a digital image of a subject using a camera with an image sensor
Data Source
Figure 1
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Figure 4A~4B
AI summary
An optical scanner device includes at least one image capture device and a transmitter of at least one aimer beam. The scanner device determines ranging to a subject using the at least one aimer beam projected to reflect off of a surface of the subject, and detects a position of the aimer-beam reflection within an image frame captured by the image-capture device, the position being a primary indicator of a distance to the subject from the optical scanner device. A secondary indicator of the distance to the subject within the image frame in combination with the first indicator is used to help detect the aimer beam reflection against noise and detect an occurrence of an optical misalignment with possible self-correction of calibration after such misalignment.