VCSEL Light Source Time-Division Driving for Thermal Control
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Solution Overview
Problem
Conventional light source devices using multiple vertical cavity surface emitting lasers (VCSELs) for distance measurement face issues with temperature rise, leading to decreased luminous efficiency and circuit deterioration due to simultaneous light emission, which affects distance measurement accuracy and reliability.
Innovation Solution
A light source device with a driving unit that controls VCSELs to emit light in a time-divided manner, synchronizing with the image sensor's frame period, and adjusts the number of simultaneous light emitting elements and groups based on temperature to curb temperature rise while maintaining distance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light emitting elements are caused to emit light simultaneously, then distance measurement can be performed, but temperature rises causing decreased luminous efficiency and circuit deterioration
Solution Approach 1:
The patent applies periodic action by dividing the light emission into multiple time slots within each frame period. Instead of simultaneous emission, VCSELs emit light in sequential time-divided manner, where different groups of VCSELs are activated in different time slots. This periodic, time-division approach reduces peak temperature while maintaining measurement functionality through multiple sequential measurements.
2Illumination intensity
If multiple light emitting elements are caused to emit light simultaneously, then light emission intensity is sufficient, but temperature rise decreases reliability
Solution Approach 1:
The patent segments the light emitting elements into multiple groups that emit light in different time slots. By dividing the VCSEL array into separate groups and activating them sequentially rather than simultaneously, the thermal load on any single group is reduced, preventing circuit deterioration and improving overall reliability while maintaining sufficient light emission intensity through cumulative effect across time slots.
3Temperature
If time-division light emission is used, then temperature rise is reduced, but distance measurement accuracy may decrease for moving subjects
Solution Approach 1:
The patent maintains continuity of useful action by performing distance measurements in multiple sequential time slots rather than a single simultaneous measurement. By continuously acquiring measurement data across different time slots with different VCSEL groups, the system compensates for subject movement through multiple samples, maintaining measurement accuracy while reducing temperature rise through time-division emission.
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
The solution effectively reduces temperature peaks, enhances light source reliability, and prevents decreases in distance measurement accuracy by optimizing light emission timing and distribution, ensuring consistent performance across varying temperatures.
Implementation Method 1
a light emitting element as a vertical cavity surface emitting laser (VCSEL) is configured such that a resonator is formed in a direction perpendicular to a semiconductor substrate surface and emits laser light in the vertical direction
Data Source
AI summary
A light source device including a light emitting unit in which multiple light emitting elements including vertical cavity surface emitting lasers are arranged is intended to curb temperature rise. A light source device according to the present technology includes a light emitting unit in which multiple light emitting elements including vertical cavity surface emitting lasers are arranged, and a driving unit that, regarding the light emitting element in the light emitting unit, causes multiple light emitting elements to be caused to emit light in a light emission target period to emit light in a time-divided manner in the light emission target period. By adopting time-division light emission, the number of light emitting elements that are caused to emit light simultaneously is reduced.