Integrated Capacitor Switching for Short Pulse Light Emission
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Solution Overview
Problem
Existing light-emitting devices for LiDAR systems, such as those used in automotive applications, face challenges in achieving short pulse widths due to parasitic inductance, which restricts range resolution and output duration, particularly when using capacitive discharge or switch control methods.
Innovation Solution
A light-emitting device configuration featuring a solid-state light-emitting element and a switching element connected in series on the outer face of a capacitor with a multilayer ceramic or semiconductor structure, reducing parasitic inductance by minimizing the distance between current loop components and using conductive parts to connect these elements directly, thereby shortening the current loop and enabling shorter pulse outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If components are arranged on the surface of a printed circuit board with distances in the order of several hundred μm, then the device structure is simple and easy to manufacture, but the parasitic inductance increases to several nH, restricting the ON duration to more than several ns
Solution Approach 1:
The patent merges the capacitor and switching element into a single integrated component structure. The switching element is formed within the capacitor body using internal electrodes as switching electrodes, eliminating the need for separate discrete components and their interconnections. This integration reduces the current loop area and parasitic inductance while maintaining ease of manufacture through a unified fabrication process.
Solution Approach 2:
The patent implements nesting by placing the switching element inside the capacitor structure. The switching element utilizes the internal electrodes of the capacitor as its switching electrodes, effectively nesting one functional element within another. This nested configuration minimizes the distance between components and reduces parasitic inductance while keeping the overall device compact and manufacturable.
2Device complexity
If a capacitive discharge method is used with resonance between parasitic inductance and capacitor, then the device structure is simple, but the pulse width of output light becomes fixed and cannot be adjusted to desired values
Solution Approach 1:
The patent implements dynamics by making the pulse width adjustable through an external signal. The switching element can be controlled to turn ON and OFF at different timings based on an external control signal, allowing the pulse width to be dynamically adjusted. This transforms the fixed pulse width characteristic of resonant circuits into a variable parameter that can be adapted to different application requirements while maintaining simple device structure.
Solution Approach 2:
The patent introduces an external control signal as an intermediary to mediate between the simple device structure and the desired pulse width adjustability. The control signal acts as a mediator that enables flexible pulse width control without requiring complex circuit modifications, allowing the system to adapt to different requirements while maintaining structural simplicity.
3Adaptability or versatility
If a switch control method is used to control ON/OFF of laser diode, then light can be output with desired pulse width to some extent, but parasitic inductance restricts the rising speed of current, requiring certain time to achieve suitable current value
Solution Approach 1:
The patent merges the switching element with the capacitor structure to minimize the current loop area. By integrating the switching element within the capacitor body and using internal electrodes as switching electrodes, the patent reduces the parasitic inductance that limits current rising speed. This merging allows faster current rise while maintaining the ability to control pulse width through external signals.
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 allows for the reduction of parasitic inductance, enabling the output of light with shorter pulses, thereby improving range resolution and reducing the size and cost of the light-emitting device.
Implementation Method 1
one or more solid-state light-emitting elements that emit light when electric power is supplied from the capacitor
Implementation Method 2
a capacitor for electric power supply... resonance between a parasitic inductance and a capacitor for electric power supply causes a laser diode to generate light with a pulse width
Data Source
AI summary
The present disclosure provides a light-emitting device that is able to output light with a shorter pulse. A light-emitting device according to the present disclosure includes a capacitor, one or more solid-state light-emitting elements that emit light when electric power is supplied from the capacitor, and a semiconductor switch that controls electric power supply from the capacitor to the solid-state light-emitting element. Furthermore, the solid-state light-emitting element is placed on an outer face of the capacitor, the semiconductor switch is placed on the outer face of the capacitor or provided inside the capacitor, and the capacitor includes a connecting electrode between outer electrodes, the connecting electrode allowing the solid-state light-emitting element and the semiconductor switch to be connected in series.