Variable-Focus Distance Ranging Using TOF and Aiming Dot Parallax
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Solution Overview
Problem
Existing imaging devices struggle to accurately determine object distance, especially with shiny surfaces, glancing angles, bright light, or when aiming dots pass through objects, leading to prolonged decode times and inefficiencies in variable-focus imaging systems.
Innovation Solution
An imaging device combines a depth sensor, such as a TOF sensor, with an imaging sensor to detect and compare distances using both time of flight and parallax-based methods, employing algorithms to resolve discordant results and optimize focal distance settings for fast and accurate scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single distance measurement technique (e.g., aiming dot parallax) is used, then the device structure remains simple, but measurement reliability deteriorates due to failures from specular reflection, glancing angles, bright light, or transparent objects
Solution Approach 1:
The patent combines multiple distance measurement techniques (ToF sensor and aiming dot parallax detection) into a unified system. The processor integrates data from both sensors, using ToF for initial distance estimation and parallax for verification, thereby improving measurement reliability while managing device complexity through coordinated operation of existing components.
Solution Approach 2:
The processor acts as an intermediary that receives distance data from both the ToF sensor and parallax detection system, compares the measurements, and determines the final object distance. This intermediary processing layer resolves discrepancies between the two measurement methods, ensuring reliable distance determination despite individual sensor limitations.
2Measurement precision
If ToF sensor is used for distance measurement, then measurement precision improves, but device size and power consumption increase
Solution Approach 1:
The system merges ToF sensor with existing imaging device components (aiming dot generator and imaging sensor). By combining these components into a unified structure, the patent achieves precise distance measurement without proportionally increasing device volume, as the ToF sensor shares spatial and functional resources with the imaging system.
Solution Approach 2:
The imaging sensor serves dual functions: capturing images for barcode scanning and detecting aiming dot parallax for distance measurement. This multi-functionality reduces the need for separate dedicated distance measurement components, thereby limiting the increase in device size while maintaining measurement precision.
3Measurement precision
If multiple distance measurement methods are combined, then distance determination accuracy improves, but processing time increases
Solution Approach 1:
The ToF sensor performs preliminary distance estimation quickly, providing an initial distance value before the more time-consuming parallax detection completes. The processor uses this preliminary data to make rapid focus adjustments, while the parallax measurement serves as verification, thereby minimizing overall processing time while maintaining accuracy.
Solution Approach 2:
The processor continuously compares distance measurements from both sensors and adjusts focus accordingly. This feedback mechanism allows the system to leverage the faster ToF sensor for initial focus setting while using parallax data for verification, reducing total processing time compared to sequential measurement approaches.
4Adaptability or versatility
If variable-focus imaging assembly is used, then adaptability to different distances improves, but focus speed and accuracy deteriorate without reliable distance measurement
Solution Approach 1:
The ToF sensor provides preliminary distance information that enables the variable-focus imaging assembly to rapidly adjust focus before image capture. This preliminary distance measurement allows the focus mechanism to move directly to the appropriate focal plane, significantly improving focus speed while maintaining adaptability across different distances.
Solution Approach 2:
The processor uses continuous distance feedback from both ToF and parallax measurements to dynamically control the variable-focus imaging assembly. This feedback loop ensures that the focus position is constantly optimized based on actual object distance, maintaining both speed and accuracy across varying operational conditions.
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 enables fast and accurate distance determination, allowing variable-focus imaging devices to achieve performance speeds comparable to fixed focus scan engines, even at close ranges, while optimizing resource usage and reducing decode times.
Implementation Method 1
a depth sensor, such as a TOF sensor
Implementation Method 2
performing an aiming pattern parallax detection in the imaging FOV
Data Source
AI summary
Imaging devices, systems, and methods for capturing and processing images, by using multiple distance determinations to set the focal position of variable-focus lens are provided. Imaging devices include a low-resourced depth sensor detecting an object distance over a first field of view (FOV). The imaging devices include an imaging sensor determining an object distance over a second FOV using parallax detection of an aiming pattern. Processors are configured to compare the two distances and, in response, to discordance perform a series of mitigations to determine a desired distance. The variable-focus lens is then set to that desired distance for subsequent image capture and indicia analysis.