Aimer Localization in Multi-Sensor Optical Scanner
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Solution Overview
Problem
Active autofocus systems in optical scanners face interference issues that affect their accuracy and reliability, particularly in long-distance scanning where background interference confuses the auxiliary measurement systems, leading to incorrect focus settings.
Innovation Solution
The system employs a laser triangulation-based active autofocus with temporal modulation of the laser signal and position matching in multiple cameras to eliminate false-positive aiming-spot detection, using controller circuitry to determine autofocus settings and interface circuitry to communicate these settings to the optical system, along with aimer spot projection and image frame capture synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If active autofocus systems use light-based signal emissions (laser spots) for distance measurement, then focusing speed is improved, but background interference causes false-positive detection and reduces reliability
Solution Approach 1:
The patent applies temporal modulation to the laser signal, causing it to oscillate or pulse at a specific frequency. This periodic action allows the system to distinguish the modulated laser signal from static or non-modulated background light interference, thereby maintaining detection accuracy while preserving the speed advantages of active autofocus
Solution Approach 2:
The patent uses temporal modulation to create a distinctive temporal signature for the laser signal, analogous to color changes. By encoding the laser signal with a specific modulation pattern (frequency, phase, or waveform), the system can differentiate it from background interference based on its unique temporal characteristics rather than relying solely on spatial or intensity properties
2Measurement precision
If passive autofocus systems perform complete focus sweeps to evaluate image contrast, then detection accuracy is improved, but latency increases and usability deteriorates
Solution Approach 1:
The system performs preliminary distance estimation using the actively modulated laser triangulation method before initiating the focus sweep. This preliminary action provides an initial focus position that is already close to the optimal setting, significantly reducing the range and time required for the subsequent contrast evaluation sweep
Solution Approach 2:
The patent introduces an intermediary measurement system (modulated laser triangulation) that provides distance information to guide the focus sweep process. This intermediary system acts as a mediator between the object and the image capture device, enabling the autofocus system to start from an informed position rather than performing a complete sweep from scratch
3Adaptability or versatility
If optical scanners capture images at long distances with large fields of view, then scanning versatility is improved, but background interference increases and detection reliability decreases
Solution Approach 1:
The patent uses temporal modulation to give the laser signal a distinctive temporal signature that differs from background light. This allows the system to distinguish the target reflection from background interference even when capturing large fields of view at long distances, maintaining detection reliability while preserving scanning versatility
Solution Approach 2:
By modulating the laser signal at a specific frequency and detecting only signals with this periodic pattern, the system can filter out non-modulated background light. This periodic action enables reliable detection at long distances with large fields of view by ignoring the static or non-periodic background interference
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 reliability of autofocus systems by distinguishing the aimer spot from interference, improving focus accuracy and reducing latency in image capture, especially in scenarios with significant background interference.
Implementation Method 1
an active autofocus system based on laser triangulation that is operative to localize the aimer in the image, convert the aimer position to determine a distance to the target
Implementation Method 2
techniques presented in this disclosure facilitate accuracy and reliability of the autofocus system using temporal modulation of the laser signal and position matching in the cameras
Data Source
Figure 1
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Figure 4A~4B
AI summary
An optical scanner determines ranging to a subject using a localization phase in which a series of image frames is received which collectively contains an aimer spot captured as a reflection off of a surface of the subject. The captured aimer spot is temporally modulated according to a modulation pattern, and the series of image frames is processed to discriminate the aimer spot based on the modulation pattern to determine a probable location of the aimer spot within at least one of the image frames of the series. A triangulation phase follows in which the probable location of the aimer spot is processed to produce the ranging determination. In an optional implementation, an assessment is made whether that probable location of the aimer spot is within a plausible location based on different device-specific positional offsets in image frames captured by different ones of the plurality of image-capture devices.