VCSEL Light Source Pulse Control for Thermal-Stable Exposure
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Solution Overview
Problem
In distance measuring systems, prolonged light emission by light source devices leads to increased temperature, reducing luminous efficiency and potentially causing oscillation stops, limiting exposure time and decreasing sensing precision due to heat generation.
Innovation Solution
The light source device incorporates a drive unit that adjusts the number of laser light emissions per frame period based on temperature detection, using vertical cavity surface emitting lasers (VCSEL) and a temperature sensor to suspend and resume light emissions, allowing for divided light emissions to inhibit temperature rise while maintaining desired exposure times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If long exposure time is set to increase exposure, then the luminous efficiency decreases and temperature rises, but sensing precision is required
Solution Approach 1:
The patent divides a single long light emission into multiple short light emissions within one frame period. The drive unit controls the laser light emitting element to perform plurality of light emissions instead of one continuous emission, thereby reducing temperature rise while maintaining total exposure time. This segmentation of the light emission process directly resolves the contradiction between exposure duration and temperature control.
Solution Approach 2:
The patent implements periodic light emissions with intervals between them. The drive unit controls the laser to emit light in multiple periodic pulses within a frame period, allowing cooling intervals between emissions. This periodic action pattern enables maintaining long total exposure time while preventing continuous heat accumulation, thus resolving the temperature-exposure time contradiction.
2Measurement precision
If long light emission duration is used to achieve desired exposure, then heat generation increases causing oscillation stop, but measurement precision is required
Solution Approach 1:
By segmenting the light emission into multiple short pulses rather than one long continuous emission, the patent prevents heat accumulation that would cause oscillation stop. The drive unit controls multiple brief emissions within a frame period, maintaining measurement precision through adequate total exposure while ensuring light source stability by avoiding thermal runaway.
Solution Approach 2:
The patent employs a temperature sensor to detect light source temperature and feeds this information back to the drive unit. The drive unit adjusts the number and timing of light emissions based on temperature feedback, preventing oscillation stop while maintaining sensing precision. This closed-loop control ensures reliability by preventing thermal damage while achieving accurate measurements.
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 effectively prevents temperature-related decreases in luminous efficiency, allowing for improved exposure and precision in distance measurement and object recognition by maintaining light emission efficiency and preventing oscillation stops.
Implementation Method 1
a plurality of laser light emitting elements; drive unit configured to drive each of the laser light emitting elements to perform a plurality of light emissions
Implementation Method 2
the laser light emitting elements include vertical cavity surface emitting lasers
Data Source
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AI summary
Exposure with sufficient optical energy is enabled while avoiding temperature rise of laser light emitting elements. Therefore, a light source device includes the plurality of laser light emitting elements and a drive unit. The drive unit drives each of the laser light emitting elements to perform a plurality of light emissions in one frame period in an image sensor that receives and captures light emitted from the plurality of laser light emitting elements and reflected by a subject.