Lighting Controller Ground Isolation for EMI-Free Trigger Timing
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Solution Overview
Problem
Noise, particularly electromagnetic interference, in lighting controllers for inspection cameras can cause incorrect lighting patterns or sequences, leading to difficulty in detecting defects in manufactured products.
Innovation Solution
The lighting controller incorporates isolated grounds, common mode filters, high-frequency filters, and a high-resolution timer to ensure noise and signal isolation, along with a capacitor bank to manage power supply during peak usage, ensuring precise timing and synchronization of light and camera triggers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If interrupts are generated closely in time to control lighting sequences, then productivity and inspection speed are improved, but electromagnetic interference and noise increase causing incorrect lighting patterns
Solution Approach 1:
The patent divides the grounding system into multiple isolated ground domains (analog ground, digital ground, LED driver ground, camera ground) rather than using a single common ground. This segmentation prevents electromagnetic interference from one domain affecting another, allowing high-speed interrupts to be generated without causing incorrect lighting patterns.
Solution Approach 2:
The patent introduces isolated ground domains as intermediary elements between different circuit components. These isolated grounds act as mediators that prevent direct electromagnetic coupling between high-speed interrupt circuits and sensitive lighting control circuits, thereby reducing noise while maintaining high inspection speed.
2Measurement precision
If multiple independently controlled light sources are activated in coordinated sequence, then measurement precision and defect detection capability are improved, but device complexity increases
Solution Approach 1:
The patent implements a single lighting controller that universally manages multiple independently controlled light sources through isolated ground domains. This multi-functional approach allows one controller to coordinate complex lighting sequences for defect detection without requiring separate control circuits for each light source, thereby improving defect detection capability while managing device complexity.
Solution Approach 2:
The isolated ground domains provide self-service by automatically preventing electromagnetic interference without requiring additional active intervention or complex shielding mechanisms. The ground isolation structure inherently protects against noise, simplifying the overall controller design while maintaining precise control over multiple light sources.
3Device complexity
If common ground planes are used in lighting controller circuits, then device complexity is reduced, but electromagnetic interference causes noise in circuits
Solution Approach 1:
The patent segments the grounding system into multiple isolated ground domains (analog ground, digital ground, LED driver ground, camera ground) rather than using a single common ground plane. This segmentation prevents electromagnetic interference from propagating between different circuit sections, effectively reducing circuit noise while maintaining manageable complexity through systematic ground isolation.
Solution Approach 2:
The patent applies different ground domains to different local circuit sections based on their specific requirements. Sensitive analog circuits receive dedicated analog ground, while high-current LED driver circuits have their own isolated ground domain. This local quality approach optimizes noise performance for each circuit section without requiring a completely complex unified grounding system.
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 design effectively reduces electromagnetic interference, ensuring accurate lighting sequences and defect detection in inspection images by maintaining precise synchronization and reducing energy consumption.
Implementation Method 1
a common mode filter is added to a direct current (DC) input
Implementation Method 2
a high frequency filter circuit is also added to a digital input line to further reduce noise
Data Source
AI summary
In an example embodiment, an improved lighting controller designed to reduce the effects of electromagnetic interference is introduced. The improved lighting controller contains various features to help ensure noise and signal isolation. First, a control board in the improved lighting controller is designed such that each of a plurality of circuits on the control board contain separate grounds, such that ground planes are isolated from one another rather than sharing a common ground. Additionally, a common mode filter is added to an alternating current input. Additionally, a high frequency filter circuit is also added to a digital input line to further reduce noise.