Optical Coupler Lead Segmentation for Noise Immunity
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Solution Overview
Problem
Optically coupled isolation devices face failures due to noise voltage generated by drastic current variations in analog-digital conversion circuits, which are not effectively insulated from input and output terminals, leading to electromagnetic induction and capacitive coupling issues.
Innovation Solution
The optical coupler design includes an optical transmitting unit with a specific arrangement of leads and a resin-molding body, where inner lead portions are closely spaced within the resin, and outer lead portions are spaced apart, reducing capacitive and magnetic coupling, and the use of equal-length input leads to cancel noise voltages, thereby enhancing noise immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If leads are arranged closely to reduce device size, then compactness is improved, but capacitive and magnetic coupling between leads increases, generating noise voltage
Solution Approach 1:
The lead structure is segmented into inner lead portions (within resin) and outer lead portions (extending from resin). The inner portions are closely spaced for compactness, while outer portions are spaced apart to reduce coupling. This segmentation allows different spatial arrangements for different functional requirements.
Solution Approach 2:
The resin-molding body acts as an intermediary that encapsulates the inner lead portions, providing electrical insulation and reducing capacitive coupling between closely spaced leads. The resin barrier prevents direct electromagnetic interaction while allowing the leads to maintain close proximity for compact device design.
2Object-affected harmful factors
If outer lead portions are spaced apart to reduce coupling, then noise voltage is reduced, but device complexity increases
Solution Approach 1:
The lead structure is segmented into inner lead portions (within resin) and outer lead portions (extending from resin). The inner portions are closely spaced for compactness, while outer portions are spaced apart to reduce coupling. This segmentation allows different spatial arrangements for different functional requirements.
Solution Approach 2:
The lead arrangement utilizes three-dimensional space by distinguishing between inner portions (z-dimension, within resin) and outer portions (x-dimension, extending from resin). This dimensional differentiation allows close spacing in one dimension while maintaining separation in another, reducing coupling without increasing overall device footprint.
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 significantly reduces noise voltage, improving the optical coupler's resistance to noise signals and preventing incorrect operation, allowing for more reliable performance in control and measurement mechanisms.
Implementation Method 1
capacitive coupling caused by parasitic capacitance between leads
Implementation Method 2
inner lead portions are within a resin-molding body
Implementation Method 3
an optical transmitting unit having a light emitting element
Implementation Method 4
an optical receiving unit having a light receiving element
Implementation Method 5
magnetic coupling between leads
Data Source
AI summary
An optical coupler includes an optical transmitting unit and an optical receiving unit in a facing arrangement. The optical transmitting unit includes a power lead having a first die-pad portion, a light emitting element on the first die-pad portion, a ground lead having a second die-pad portion, and an integrated circuit on the second die-pad portion. The integrated circuit has a power pad portion, a light emitting element pad portion, and input pad portions thereon. An inter-center distance between an inner lead of the first input lead and an inner lead of the second input lead is equal to or less than an inter-center distance between an outer lead of the first input lead and an outer lead of the second input lead.