Light-Emitting Device Waveform Stabilization via Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light emitting devices struggle to maintain consistent pulsed light waveforms due to temperature variations and component precision issues, leading to inaccuracies in distance measurement and increased production costs.
Innovation Solution
A light emitting device with a differentiation circuit comprising a resistor and capacitor in parallel, connected in series with a switching element, and a voltage controlling part that measures and adjusts the voltage to maintain a predetermined waveform, compensating for temperature and precision variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermostatic device is used to maintain constant temperature of the light source and driving circuit, then the waveform stability and measurement accuracy are improved, but the device complexity and power consumption increase significantly
Solution Approach 1:
The patent replaces the mechanical/thermal thermostatic control system with an electrical control system. By using a differentiating circuit to generate pulsed current and an ADC to detect light intensity, the system achieves waveform stabilization through electrical parameter control rather than thermal management, thereby eliminating heaters and Peltier elements.
Solution Approach 2:
The patent changes the control parameter from temperature (thermal domain) to voltage/current (electrical domain). By controlling the driving voltage and current pulse width through the differentiating circuit, the system stabilizes the light output waveform without needing to maintain constant temperature, thus simplifying the device structure.
2Manufacturing precision
If high precision components and strict component selection are used to reduce waveform variations, then the manufacturing precision is improved, but the production cost increases
Solution Approach 1:
The patent implements a self-adjusting system where the ADC continuously detects the light intensity and feeds back to the microcontroller, which automatically adjusts the driving voltage through the differentiating circuit. This closed-loop control compensates for component variations without requiring high-precision components, allowing the use of standard commercial parts while maintaining waveform consistency.
Solution Approach 2:
The patent introduces a feedback mechanism using the ADC to detect light intensity and the microcontroller to adjust driving parameters. This feedback loop compensates for variations in component characteristics, enabling the system to maintain stable waveforms using standard components rather than requiring expensive high-precision parts.
3Measurement precision
If the driving current is applied for a very short period to generate narrow pulsed light, then the pulse width is reduced and measurement accuracy is improved, but the circuit complexity increases due to the need for precise timing control
Solution Approach 1:
The patent introduces a differentiating circuit as an intermediary between the power supply and the light source. This circuit naturally generates short-duration current pulses in response to voltage changes, eliminating the need for complex timing control circuitry. The differentiating action inherently produces the desired narrow pulse width through its electrical characteristics rather than through complex switching 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
The device stabilizes pulsed light waveforms, reducing temperature and precision-related variations, thereby enhancing measurement accuracy and reducing production costs by automatically adjusting voltage to maintain consistent peak intensity and symmetry.
Implementation Method 1
generation of inrush current to a capacitor and subsequent voltage drop at a resistor are used to make pulse-like current corresponding to one pulse flow to an LD momentarily
Implementation Method 2
subsequent voltage drop at a resistor
Implementation Method 3
the LD emits light that has a pulse-like shape at first, but that gradually attenuates to have a constant intensity. This oscillation in light intensity, which occurs in the initial stage of the light emission and gradually attenuates, is called 'relaxation oscillation'
Data Source
AI summary
Provided is a technology for suppressing variations in the waveform of a light emission pulse caused by various factors in a light-emitting device. A light-emitting device is provided with: a light source 101 in which relaxation oscillation occurs immediately after energization; a light source drive circuit 104 which includes a differentiation circuit 102 having a resistor and a capacitor connected in parallel, and in which a switching element 103 for voltage application is connected in series with the differentiation circuit; a power supply circuit 105; a light-reception element 107 which detects pulsed light emitted from the light source 101; and a voltage control unit 109 which controls an output voltage from the power supply circuit 105 in correspondence with the waveform of the detected pulsed light.