VCSEL Array Wiring Layout for Low-Impedance Ranging Emitters
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Solution Overview
Problem
As the number of light-emitting elements in a VCSEL increases, the length of their wirings grows, leading to high impedance and significant differences in impedance between wirings, which affects the performance of light-emitting devices and ranging devices.
Innovation Solution
A light-emitting device with a two-dimensional array of light-emitting elements, featuring optimized wiring structures that include horizontal and vertical wirings connected to selection and drive circuits, reducing impedance and impedance differences by distributing capacitors symmetrically to accumulate and supply charges efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of light-emitting elements is increased, then the light emission capability is improved, but the wiring length increases leading to high impedance and significant impedance differences
Solution Approach 1:
The patent divides the wiring structure into two independent sets: first terminal wirings connected to first terminals and second terminal wirings connected to second terminals. Each set is independently configured with horizontal and vertical wirings forming a mesh pattern, which segments the current path and reduces overall impedance while maintaining uniform current distribution across all light-emitting elements
Solution Approach 2:
The patent transitions from conventional one-dimensional linear wiring to a two-dimensional mesh wiring structure with horizontal and vertical components. This dimensional change allows current to flow through multiple parallel paths, effectively reducing impedance and equalizing impedance across different wiring segments connecting to various light-emitting elements
2Quantity of substance
If the number of light-emitting elements is increased, then the light emission capability is improved, but the impedance of each wiring becomes great
Solution Approach 1:
By separating wirings into two independent terminal wiring sets connected to opposite terminals, the patent creates parallel current paths that reduce the effective impedance of each individual wiring segment while maintaining the ability to drive a large number of light-emitting elements
Solution Approach 2:
The two-dimensional mesh wiring structure provides multiple parallel conduction paths for current flow, significantly reducing the effective impedance compared to linear wiring configurations, thereby improving reliability when driving numerous light-emitting elements
3Quantity of substance
If the number of light-emitting elements is increased, then the light emission capability is improved, but the difference between impedances of wirings becomes great
Solution Approach 1:
The patent creates symmetrical wiring segments on both sides of the light-emitting element array, with each terminal wiring set having corresponding horizontal and vertical components. This segmentation and symmetry ensure that all light-emitting elements experience nearly identical impedance conditions, achieving uniformity despite the large number of elements
Solution Approach 2:
While the overall structure uses symmetry, the patent applies asymmetry principles by creating two distinct but complementary terminal wiring sets that connect to opposite terminals. This asymmetric approach with respect to terminal connection points actually achieves symmetric impedance characteristics across all elements, balancing the electrical paths
Data Source
AI summary
A light-emitting device and a ranging device that optimize structures of wirings for light-emitting elements. A light-emitting device includes: a plurality of light-emitting elements disposed in a two-dimensional array, and each include first and second terminals; a plurality of first terminal wirings that include N horizontal wirings (N represents an integer equal to or more than two), and N vertical wirings electrically connected to the horizontal wirings, respectively, and to the first terminals of the light-emitting elements; a plurality of second terminal wirings electrically connected to the second terminals of the light-emitting elements, and to N of the light-emitting elements; a plurality of selection circuits electrically connected to ones of the first and second terminal wirings, and select the light-emitting element that is caused to produce light; and a plurality of drive circuits electrically connected to other ones of the first and second terminal wirings to drive the light-emitting elements.