Light Emitting Device Cover Body with Non-Uniform Thickness
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Solution Overview
Problem
Light emitting devices face reliability issues due to stress caused by differences in thermal expansion coefficients between components, leading to plastic deformation and damage to the joining portions and window bodies.
Innovation Solution
A light emitting device design featuring a base with a supporting part and frame, a cover body with specific thickness portions that absorb stress through elastic deformation, and a light-transmissive body to reduce stress concentrations and maintain mechanical strength, while using materials with appropriate thermal conductivity and expansion coefficients for airtight sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cover body with uniform thickness is used, then the manufacturing process is simple, but stress concentration occurs at the joining portion between the cover body and frame part, leading to plastic deformation and damage
Solution Approach 1:
The cover body is designed with non-uniform thickness, where the first portion (at the joining area with the frame part) has a greater thickness than the second portion (inner area). This local quality variation concentrates stress in the thicker first portion, preventing stress concentration and plastic deformation at the joining portion, thereby improving reliability without significantly complicating manufacturing
Solution Approach 2:
The thickness parameter of the cover body is deliberately varied across different regions. By changing the thickness parameter from uniform to non-uniform (with the first portion being thicker), the stress distribution is optimized to prevent damage at critical joining areas while maintaining overall structural integrity
2Weight of stationary object
If the cover body is made thin to reduce weight and size, then the device becomes more compact, but the mechanical strength and stress resistance are reduced
Solution Approach 1:
The cover body employs local quality variation with different thickness regions: the first portion near the frame part has greater thickness for strength and stress resistance, while the second portion in the inner area has reduced thickness to minimize weight. This selective thickness distribution achieves optimal balance between weight reduction and mechanical strength
Solution Approach 2:
The cover body is constructed as a composite structure with regions of different thickness, effectively combining the benefits of both thin (lightweight) and thick (strong) areas in a single component, achieving optimal weight-strength trade-off
3Adaptability or versatility
If materials with different thermal expansion coefficients are used for various components, then each component can be optimized for its specific function, but stress occurs during thermal cycling, leading to damage at joining portions
Solution Approach 1:
The thickness parameter of the cover body is optimized to compensate for thermal expansion differences between materials. The increased thickness at the first portion provides additional compliance and stress absorption capacity during thermal cycling, accommodating the harmful effects of differential thermal expansion while maintaining functional optimization of different components
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 design effectively reduces stress-induced deformation and damage, enhancing the reliability and durability of the light emitting device by distributing stress and maintaining airtightness.
Implementation Method 1
a second portion having a thickness greater than a thickness of the first portion and extending inward from the first portion, then bending and extending downward
Implementation Method 2
at least one light-transmissive body covering the at least one opening
Data Source
AI summary
A light emitting device includes a base having a supporting part and a frame part disposed on an upper surface of the supporting part; a light emitting element mounted on the upper surface of the supporting part at a location interior of the frame part; a cover body fixed to an upper surface of the frame part and defining an opening at a location interior of the frame part in a top view; and a light-transmissive body covering the at least one opening. The cover body includes: a first portion disposed on the upper surface of the frame part, a second portion extending inward from the first portion and then bending and extending upward or downward so as to be spaced from an inner lateral surface of the frame part or a plane that includes an inner lateral surface of the frame part, and a third portion connected to the second portion and defining the opening.