Array Dot VCSEL Driving for Distance Measurement Resolution
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Solution Overview
Problem
Existing distance measurement systems using vertical cavity surface emitting lasers face limitations in increasing resolution without increasing the number of light sources, as both random and array dot arrangements have constraints in light source identification and resolution.
Innovation Solution
A distance measurement system employing an array dot arrangement of light sources, where two adjacent light sources are driven simultaneously and independently, with a controller managing their operation to create intensity peaks and adjust sensitivity, allowing for higher resolution without increasing the number of light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of light sources is increased in an array dot arrangement, then the resolution of the distance image is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies dynamic control to the light sources by alternating between individual driving and simultaneous driving modes. This dynamic operation allows the system to achieve higher effective resolution through temporal multiplexing, where the same physical light sources produce multiple distinguishable patterns over time, eliminating the need for additional hardware light sources
Solution Approach 2:
The system uses periodic alternating driving patterns where light sources are driven individually in one period and simultaneously in another period. This periodic action creates temporally separated intensity peak patterns that can be distinguished by the event detection sensor, effectively doubling the resolvable features without adding more light sources
2Illumination intensity
If two light sources are driven simultaneously, then intensity peaks are enhanced for better detection, but the ability to identify individual light sources is reduced
Solution Approach 1:
The patent resolves this contradiction by using periodic alternating driving: in the first period, light sources are driven individually for identification; in the second period, they are driven simultaneously for enhanced intensity peaks. The event detection sensor captures events from both periods, and the controller processes the temporal sequence to maintain identification capability while benefiting from enhanced intensity during simultaneous driving
Solution Approach 2:
The system performs preliminary individual driving of light sources before simultaneous driving, establishing baseline identification information. This preliminary action allows the system to later interpret the simultaneous driving patterns by referencing the previously established individual light source characteristics, thus maintaining identification 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 approach enhances the resolution of distance images by providing features in both spatial and time-axis directions, enabling accurate distance information acquisition without increasing the number of light sources, thus overcoming the limitations of traditional arrangements.
Implementation Method 1
a surface emitting semiconductor laser that projects light of a predetermined pattern onto a subject
Implementation Method 2
an event detection sensor that receives light reflected off the subject and detects, as an event, that a change in luminance of a pixel exceeds a predetermined threshold
Data Source
AI summary
A distance measurement system according to the present disclosure includes: a surface emitting semiconductor laser that projects light of a predetermined pattern onto a subject; an event detection sensor that receives light reflected off the subject and detects, as an event, that a change in luminance of a pixel exceeds a predetermined threshold; and a controller that controls the surface emitting semiconductor laser and the event detection sensor. An arrangement of light sources of the surface emitting semiconductor laser is an array dot arrangement in which the light sources are two-dimensionally arranged in an array form. With two light sources that are adjacent in the array dot arrangement as a unit of driving, the controller drives the two light sources to be on at the same time in a period between respective times when the two light sources are driven to be on independently of each other.