VCSEL Light Source Pulsing for Exposure and Temperature Control
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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
A light source device with a drive unit that controls the number of laser light emissions in one frame period based on temperature detection, using vertical cavity surface emitting lasers (VCSEL) and a temperature sensor to inhibit temperature rise by suspending and resuming light emission, allowing for adjustable light emission duration and interval.
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 the sensing precision requires sufficient exposure time
Solution Approach 1:
The light source device performs multiple light emissions within one frame period instead of continuous emission. The drive unit controls the laser light emitting elements to emit light in discrete pulses (e.g., first light emission, second light emission, third light emission) separated by intervals where emission is suspended, allowing temperature to decrease between pulses while accumulating sufficient total exposure time for sensing precision.
Solution Approach 2:
The system dynamically adjusts the light emission strategy based on temperature conditions. The drive unit suspends and resumes light emission according to detected temperature, changing the emission pattern from static continuous operation to dynamic pulsed operation that adapts to thermal conditions, thereby maintaining both exposure time and temperature control.
2Reliability
If continuous light emission is performed to maintain luminous efficiency, then temperature rises causing oscillation stop, but interrupting emission reduces exposure time
Solution Approach 1:
The drive unit implements periodic light emission with suspended intervals. Multiple light emissions are performed within one frame period with temperature-based suspension and resumption, ensuring the light source operates within safe temperature ranges while maintaining cumulative exposure time sufficient for accurate sensing.
Solution Approach 2:
The drive unit detects temperature and uses this feedback to control light emission. When temperature exceeds thresholds, emission is suspended; when temperature decreases below thresholds, emission resumes. This feedback mechanism maintains reliability by preventing oscillation stop while managing exposure time through adaptive emission control.
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 prevents temperature-related decreases in luminous efficiency, enabling longer exposure times and improved sensing precision while maintaining light emission efficiency.
Implementation Method 1
a plurality of laser light emitting elements
Implementation Method 2
a temperature sensor configured to detect a temperature near the laser light emitting elements
Implementation Method 3
an image sensor that receives and captures light emitted from the plurality of laser light emitting elements and reflected by a subject
Data Source
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.