VCSEL Drive Circuit for Stable Short-Pulse Ranging
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Solution Overview
Problem
Existing ranging sensors face challenges in stabilizing the emission of light pulses with short pulse widths by the VCSEL, which affects the precision of ranging measurements.
Innovation Solution
A drive circuit is designed to include a n-channel field effect transistor, a capacitor for grounding the gate with alternating current, and a source drive circuit to manage the inputted pulse signal, enabling stable emission of light pulses with short pulse widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the VCSEL is driven to emit light pulses with short pulse width to increase ranging precision, then the ranging precision is improved, but the stability of light pulse emission deteriorates
Solution Approach 1:
The drive circuit is segmented into multiple independent functional blocks: a pulse signal input terminal, a current control circuit with switch element, and a VCSEL array. This segmentation allows each block to be optimized independently - the current control circuit can be designed specifically to maintain stability while the pulse width is controlled by the input signal, thus resolving the contradiction between short pulse width and stable emission.
Solution Approach 2:
A current control circuit is introduced as an intermediary between the pulse signal input and the VCSEL array. This intermediary circuit actively regulates the drive current to maintain stable emission characteristics while allowing the pulse width to be controlled by the input signal, thereby enabling both short pulse width and stable emission to coexist.
2Measurement precision
If the pulse width of light pulse is decreased to improve ranging precision, then the measurement accuracy is improved, but the control difficulty increases
Solution Approach 1:
The patent replaces direct mechanical/electrical control of the VCSEL with an electric field-based control mechanism using an electric field effect transistor. The gate voltage controls the channel conductivity, which in turn controls the drive current to the VCSEL array. This substitution provides precise, stable, and easily controllable current regulation, making it simple to generate short pulses with controlled width while maintaining emission stability.
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 proposed solution effectively stabilizes the emission of light pulses with short pulse widths, enhancing the ranging precision of the sensor by addressing the instability issues in existing technologies.
Implementation Method 1
a n-channel field effect transistor including: a gate; a drain into which an electric current that is part of a drive current that drives a light-emitting element flows; and a source
Implementation Method 2
a capacitor that grounds the gate by means of alternating current
Implementation Method 3
a light-emitting element that emits light pulses
Data Source
AI summary
A drive circuit includes: a n-channel field effect transistor including a gate, a drain into which an electric current that is part of a drive current that drives a light-emitting element flows, and a source; a capacitor that grounds the gate by means of alternating current; and a source drive circuit that drives the source through a signal that is in accordance with an inputted pulse signal.