PCB Wiring Inductance Control for Short Pulse Emission
Solution Overview
Problem
Existing circuits face challenges in emitting pulsed light with a pulse width of 2 ns or less due to frequency characteristics deterioration caused by wiring inductance, leading to increased attenuation and laser interference in distance measurement devices.
Innovation Solution
A circuit design incorporating a PCB wiring pattern with calculated inductance not greater than 1.4 nH, including a voltage generating circuit, a light emitting element, a charge capacitor, and a switching element, to reduce attenuation and enable emission of pulsed light with a pulse width of 2 ns or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional circuit with standard PCB wiring is used to emit pulsed light, then the circuit structure is simple and easy to manufacture, but the inductance of the wiring pattern causes frequency characteristics to deteriorate, making it difficult to emit pulsed light with a pulse width of 2 ns or less
Solution Approach 1:
The patent applies parameter changes by optimizing the PCB wiring pattern dimensions (length L, width W, thickness H) to control the inductance component. By changing the physical parameters of the wiring pattern, the inductance is reduced to 1.4 nH or less, enabling the circuit to emit pulsed light with a pulse width of 2 ns or less while maintaining manufacturing simplicity.
2Ease of manufacture
If the PCB wiring pattern dimensions are not optimized, then the manufacturing process is simpler, but the inductance increases causing attenuation value to exceed 3 dB
Solution Approach 1:
The patent specifies precise parameter ranges for the PCB wiring pattern (length L, width W, thickness H) to control the inductance component and reduce signal attenuation. By optimizing these parameters, the inductance is controlled to 1.4 nH or less, ensuring the attenuation value remains at 3 dB or less while keeping the wiring pattern manufacturable using standard PCB techniques.
3Device complexity
If pulsed light with pulse width greater than 2 ns is emitted, then the circuit can operate with standard components and wiring, but laser interference occurs due to unnecessary internal reflection, increasing deviation of distance measurement values
Solution Approach 1:
The patent uses parameter changes in the PCB wiring pattern to reduce inductance to 1.4 nH or less, enabling the emission of pulsed light with a pulse width of 2 ns or less. This short pulse width prevents laser interference and internal reflection, thereby improving distance measurement accuracy without requiring additional optical mechanisms or increasing device complexity.
4Measurement precision
If an optical mechanism is added to avoid laser interference, then distance measurement accuracy is maintained, but production cost increases and size reduction is hindered
Solution Approach 1:
The patent replaces the need for optical mechanisms with an optimized electrical circuit design. By controlling the PCB wiring pattern parameters to achieve low inductance (1.4 nH or less), the circuit directly emits short pulses (2 ns or less) that prevent laser interference, eliminating the need for additional optical components and simplifying the overall device structure.
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 solution effectively reduces attenuation to less than 3 dB, allowing for accurate and cost-effective distance measurement by minimizing the size of the main structure and eliminating the need for optical mechanisms to avoid laser interference.
Implementation Method 1
the circuit wiring includes a PCB wiring pattern having a pattern length 'L', a pattern width 'W', a pattern thickness 'H', and an inductance component that is calculated as follows: 0.0002L[(log(2×L)/(W+H))+0.2235((W+H)/L)+0.5] (μH)
Implementation Method 2
a light emitting element that emits pulsed light
Data Source
Figure 1~2
Figure 3
AI summary
A technique for decreasing attenuation of emitted pulsed light with a pulse width of 2 ns or less is provided. A light emitting circuit 100 configured to emit pulsed light includes a boosting block 101, a laser diode 103, a wiring 105, a charge capacitor 102 with its end connected to the wiring 105, and a switching element 104 configured to be turned on or off to apply voltage to the laser diode 103. The inductance of the wiring 105 is not greater than 1.4 nH. The laser diode 103 emits pulsed light with a pulse width of 2 ns or less.