Aiming Light Assembly for Rapid Distance Determination in Imaging Readers
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Solution Overview
Problem
Existing imaging readers face challenges in expeditiously focusing over an extended working distance range, as contrast-based automatic focusing methods are slow and unsuitable for fast and dynamic industrial applications.
Innovation Solution
The implementation of an aiming light assembly that directs a light spot along an aiming axis, with a controller to capture and compare images with and without the aiming light, allowing for rapid determination of target distance through image processing, enabling quick adjustment of the focusing element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contrast-based automatic focusing is used, then focusing can be achieved over extended working distance range, but focusing speed becomes slow and unacceptable for industrial applications
Solution Approach 1:
The patent replaces the mechanical/iterative contrast-based focusing system with an optical ranging system using an aiming light assembly and time-of-flight measurement. Instead of capturing and processing many successive images to determine focus, the system uses light travel time measurement to directly determine target distance, enabling instantaneous focusing without iterative processing.
Solution Approach 2:
The patent introduces an aiming light assembly as an intermediary component that projects a visible light pattern onto the target. This intermediary light source enables the system to measure target distance through time-of-flight or phase shift methods, providing a direct measurement mechanism that bypasses the slow contrast-based focusing process while maintaining accurate focusing capability over extended ranges.
2Measurement precision
If multiple images over successive frames are captured for contrast-based focusing, then focus determination is possible, but processing time increases and performance degrades
Solution Approach 1:
The patent performs preliminary action by using the aiming light assembly to pre-measure the target distance before image capture. The time-of-flight or phase shift measurement of the aiming light provides advance information about target range, allowing the system to pre-configure focus settings before capturing the actual target image. This eliminates the need for capturing and processing multiple successive frames for focus determination.
3Adaptability or versatility
If a variable focusing element is provided in the far imager, then focusing on far-out targets is possible, but the system becomes more complex and harder to control expeditiously
Solution Approach 1:
The patent implements feedback by using the aiming light measurement system to continuously determine target distance and automatically adjust the variable focusing element accordingly. The measured range information feeds back to the focusing control mechanism, enabling automatic and expeditious adjustment of the focusing element without complex manual control or iterative processing, thereby managing system complexity while maintaining extended range capability.
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 method allows for fast and accurate focusing over a wide range of working distances without degrading reader performance, unlike traditional contrast-based methods, by using sub-frames and sub-regions for precise positioning of the aiming light spot.
Implementation Method 1
an energizable aiming assembly for directing an aiming light spot along an aiming axis to a target when energized
Implementation Method 2
an imaging assembly for capturing a first image of the target containing the aiming light spot
Implementation Method 3
for capturing return light scattered and/or reflected from the target being imaged
Implementation Method 4
An image pre-processor compares first image data from the first image with second image data from the second image over a common fractional region of both frames to obtain a position of the aiming light spot in the first image
Data Source
AI summary
A distance to a target to be read by image capture over a range of working distances is determined by directing an aiming light spot along an aiming axis to the target, and by capturing a first image of the target containing the aiming light spot, and by capturing a second image of the target without the aiming light spot. Each image is captured in a frame over a field of view having an imaging axis offset from the aiming axis. An image pre-processor compares first image data from the first image with second image data from the second image over a common fractional region of both frames to obtain a position of the aiming light spot in the first image, and determines the distance to the target based on the position of the aiming light spot in the first image.