Hybrid Autofocus via Laser Scanning and Time-of-Flight
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Solution Overview
Problem
Passive autofocus systems in cameras struggle with accurate focus in low-light and low-contrast situations, while active systems are limited by a small number of focus points, leading to out-of-focus images and difficulty in capturing images with uniform colors or large objects.
Innovation Solution
The integration of embedded laser beam scanning (LBS) projectors that project visible or nonvisible light to assist passive autofocus and utilize time-of-flight measurement for active autofocus, providing hybrid autofocus features with dynamic focus points by combining red, green, blue, and infrared laser light sources and a time-of-flight measurement system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If passive autofocus systems are used, then focus accuracy is achieved in normal lighting conditions, but focus accuracy deteriorates in low-light and low-contrast situations
Solution Approach 1:
An infrared illuminator is introduced as an intermediary device to provide additional illumination in low-light conditions. The infrared light is invisible to humans but detectable by the image sensor, enabling the passive autofocus system to function effectively in dark environments by providing the necessary contrast without interfering with normal photography
Solution Approach 2:
The system utilizes infrared illumination to change the effective color spectrum available for autofocus. By adding infrared wavelengths to the visible spectrum, the system creates additional contrast information that enables accurate focus determination in conditions where visible light alone is insufficient
2Speed
If active autofocus systems are used, then focus speed is improved, but the number of focus points is limited
Solution Approach 1:
The patent merges active autofocus (providing speed through infrared illumination) with passive autofocus (providing multiple focus points through image analysis). The hybrid system combines the strengths of both approaches: the infrared illuminator enables fast initial focus acquisition, while the image sensor simultaneously captures contrast information across the entire field of view, allowing multiple focus points to be determined
Solution Approach 2:
The infrared illuminator serves multiple functions: it provides illumination for the image sensor in low-light conditions, enables active autofocus for distance measurement, and simultaneously provides contrast information for passive autofocus across the entire field of view. This multi-functionality allows the system to achieve both fast focus speed and multiple focus points
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
Enhances autofocus performance in low-light and low-contrast environments by providing additional contrast and accurate distance measurement at multiple points, reducing the likelihood of out-of-focus images and improving focus accuracy on small objects.
Implementation Method 1
utilize time-of-flight measurement for active autofocus
Data Source
AI summary
An apparatus with autofocus includes a scanning laser projector to provide autofocus assist. The scanning laser projector may project visible or nonvisible light in contrasting patterns to provide passive autofocus assist. The scanning laser projector may include a time-of-flight determination circuit to measure distances to provide active autofocus assist. Passive and active autofocus assist are combined to provide hybrid autofocus assist.