Optical Sensor Land Pattern Layout for Stray Light Reduction
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Solution Overview
Problem
Existing methods for reducing stray light in optical sensors, such as using black resist or light-shielding coating solutions, can be insufficient when these solutions cannot be used due to cost or equipment constraints, or when they are unevenly formed, leading to unreliable mounting and detection accuracy issues.
Innovation Solution
The optical sensor incorporates a land pattern on the substrate with specific patterns extending in parallel and perpendicular directions to the land centers, effectively reducing stray light without relying on light-shielding members. These patterns are designed to connect the light emitting and receiving units to the substrate while minimizing stray light entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-shielding member (black resist or light-shielding coating solution) is used to cover the substrate surface, then stray light entering the light receiving unit is reduced, but manufacturing cost increases and equipment constraints arise
Solution Approach 1:
The invention extracts the light-shielding function from external coating materials (black resist, light-shielding coating solution) and integrates it directly into the substrate structure through a pattern formed on the substrate surface. This eliminates the need for separate light-shielding members and their associated manufacturing processes, thereby reducing manufacturing cost and equipment constraints while maintaining stray light reduction effectiveness
Solution Approach 2:
The pattern formed on the substrate serves multiple functions: it acts as a light-shielding structure to prevent stray light, serves as a mounting land for electrical connection, and integrates these functions into a single structural element. This multi-functionality eliminates the need for separate light-shielding coatings and reduces manufacturing complexity
2Measurement precision
If a light-shielding member is used to reduce stray light, then detection accuracy improves, but mounting reliability deteriorates due to expansion of mounting lands
Solution Approach 1:
The light-shielding pattern is applied locally only in specific regions where stray light would affect the light receiving unit, rather than covering the entire substrate surface. This localized approach maintains detection accuracy by blocking stray light paths while preserving mounting land areas in other regions, thereby maintaining mounting reliability through proper heat dissipation and electrical connection areas
3Object-affected harmful factors
If black resist or light-shielding coating solution is used, then stray light is reduced, but formation uniformity deteriorates leading to unreliable results
Solution Approach 1:
The invention replaces the chemical coating process (application of black resist or light-shielding coating solution) with a physical structure formed through standard PCB manufacturing techniques such as photoetching or laser processing. This substitution eliminates the formation uniformity issues associated with liquid coating methods, as the pattern can be precisely defined by photomask alignment or laser positioning, ensuring consistent and reliable stray light reduction across all substrates
Data Source
AI summary
An optical sensor includes a pattern extending in a first direction substantially parallel to a line connecting two land centers that are connected to the light emitting unit. The pattern in the first direction is formed on at least one of right and left relative to the line connecting the two land centers. The optical sensor also includes a pattern extending in a direction between lands of the light emitting unit. The direction between the lands of the light emitting unit is a second direction substantially perpendicular to the first direction.