Pulsed Light Emitter Circuit for Low-Inductance Distance Sensing
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Solution Overview
Problem
Current light emitting devices face challenges in achieving high-speed, high-accuracy distance measurement over long distances using the direct method, as the phase difference method reduces accuracy when increasing measurement range, and heat dissipation issues arise from high-current pulsed light emission, complicating the integration of drivers and light sources on heat dissipation bases.
Innovation Solution
A light emitting device configuration that includes a light emitting element, a switch element, a capacitive element connected in parallel, and a resistance element between the capacitive element and the power supply, allowing for controlled charge time and resonance-based high-current pulse generation, minimizing inductance and optimizing heat dissipation through a heat dissipation base with high thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-current pulsed light emission is used to achieve high-speed, high-accuracy distance measurement, then measurement accuracy and speed are improved, but heat dissipation issues arise and device complexity increases
Solution Approach 1:
The light emitting device is segmented into distinct functional modules: light emitting elements (VCSELs) mounted on a heat dissipation base, separate driver circuits, and capacitive elements positioned to minimize inductance. This modular segmentation allows optimized heat management for the light source while separating the high-current switching functions.
Solution Approach 2:
Capacitive elements serve as intermediaries between the power supply and light emitting elements, providing controlled charge discharge to generate high-current pulses. The capacitors act as energy storage intermediaries that enable precise pulse timing and current control without requiring continuous high current from the power supply, thereby reducing overall heat generation.
2Device complexity
If driver and light source are integrated on heat dissipation base, then device complexity is reduced, but heat dissipation becomes more difficult
Solution Approach 1:
The light emitting elements are extracted from the driver circuitry and mounted separately on the heat dissipation base. This extraction allows the driver circuits to be positioned away from the primary heat source, enabling independent thermal management. The heat dissipation base is dedicated solely to cooling the light emitting elements, while driver components can be thermally managed separately or positioned in cooler regions.
3Speed
If inductance is minimized in current path, then pulse characteristics are improved, but device layout complexity increases
Solution Approach 1:
The current path is merged into a compact, direct route by positioning capacitive elements immediately adjacent to the light emitting elements on the heat dissipation base. This merging eliminates unnecessary trace lengths and via transitions, minimizing inductance. The capacitive elements are electrically connected to the light emitting elements through short, direct conductive paths, achieving low inductance without requiring complex multi-layer routing.
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 configuration enables efficient high-speed, high-accuracy distance measurement by minimizing inductance in the current path, reducing heat generation, and improving pulse characteristics, allowing for reliable long-distance measurements while maintaining high accuracy.
Implementation Method 1
a capacitive element that is connected in parallel to the light emitting element, and that discharges a charged electric charge to the light emitting element
Implementation Method 2
optimizing heat dissipation through a heat dissipation base with high thermal conductivity
Data Source
AI summary
A light emitting device includes: a light emitting element; a switch element that is connected in series to one of electrodes of the light emitting element, and that drives the light emitting element; a capacitive element that is connected in parallel to the light emitting element, and that discharges a charged electric charge to the light emitting element; and a resistance element provided between the capacitive element and a power supply that charges the capacitive element on a same base.