Light Emitting Element Array ESD Shielding Strategy
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Solution Overview
Problem
Existing light emitting element arrays are vulnerable to electrostatic discharge (ESD) damage, with the degree of damage depending on the path length of current wiring, leading to uneven stress and variation in wavelength spectrum, which can deteriorate optical transmission quality.
Innovation Solution
A light emitting element array configuration where at least one emission aperture of the light emitting unit at the shortest path length is shielded, and at least one at the longest path length is not, to reduce variation in wavelength spectrum and enhance ESD resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If all light emitting elements are left unshielded to maximize optical output, then the optical transmission intensity is improved, but the vulnerability to ESD damage increases due to uneven current path lengths
Solution Approach 1:
The patent applies different treatments to different light emitting elements based on their position in the array. Elements at positions with shorter current path lengths (which are more vulnerable to ESD) are shielded, while elements at positions with longer path lengths (less vulnerable) are left unshielded to contribute to optical output. This local differentiation resolves the contradiction between maximizing optical output and protecting against ESD damage.
2Reliability
If light emitting elements with shorter path lengths are shielded to reduce ESD damage, then the reliability is improved, but the total optical output is reduced
Solution Approach 1:
The patent changes the operational state parameter (shielded vs. unshielded) of light emitting elements based on their position-specific vulnerability to ESD. By selectively shielding only those elements at positions with shorter current path lengths, the patent minimizes the reduction in optical output while achieving the goal of reducing ESD damage. This selective parameter change resolves the contradiction between reliability improvement and optical output maintenance.
3Reliability
If uniform shielding is applied to all light emitting elements to maximize ESD protection, then the reliability is improved, but the optical transmission quality deteriorates due to loss of wavelength spectrum diversity
Solution Approach 1:
The patent applies selective shielding based on the local characteristics (current path length) of each light emitting element position. This local quality approach ensures that only the necessary elements are shielded, maintaining the wavelength spectrum characteristics of unshielded elements while providing ESD protection where most needed. This resolves the contradiction between uniform ESD protection and wavelength spectrum uniformity.
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 reduces the impact of ESD on the light emitting element array, minimizing wavelength spectrum variation and maintaining optical transmission quality by shielding the most vulnerable unit and ensuring the least affected unit contributes to the optical output.
Implementation Method 1
plural light emitting elements connected in parallel to each other by a wiring connected to a terminal that supplies a current
Implementation Method 2
one or more second light emitting elements each having a shielded light emission aperture
Data Source
AI summary
A light emitting element array includes a single semiconductor substrate, a plurality of semiconductor elements, which are formed on the single semiconductor substrate, and each of the semiconductor elements including a first distributed Bragg-reflector, an active layer formed over the first distributed Bragg-reflector, and a second distributed Bragg-reflector formed over the active layer. The array includes an electrode pad formed over the second distributed Bragg-reflector and a wiring formed at least partly over the second distributed Bragg-reflector and extending from the electrode pad toward the semiconductor elements. The semiconductor elements include a first semiconductor element, configured to emit laser light, and a second semiconductor element configured not to emit laser light and disposed at a position which is shorter distance along the wiring from the electrode pad than a distance along the wiring from the electrode pad to a position of the first semiconductor element.