Optical Sensor Substrate Absorption for Stray-Light Control
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Solution Overview
Problem
Existing optical sensors face issues with stray light entering the light receiving unit due to gaps between light shielding members, leading to detection accuracy deterioration, and mounting defects that allow heat escape.
Innovation Solution
The optical sensor incorporates a light absorbing material on the opposite surface of the substrate to the light emitting and receiving units, forming a light shielding layer that absorbs stray light without affecting mountability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a black resist or light shielding coating material is used to prevent stray light, then stray light suppression is improved, but gaps are formed between the light emitting unit and the shielding member, allowing light to pass through and reducing shielding effectiveness
Solution Approach 1:
A light absorbing material is introduced as an intermediary element on the opposite surface of the substrate. This material absorbs stray light that passes through the substrate, preventing it from reaching the light receiving unit. The light absorbing material serves as a mediator that complements the light shielding member, filling the functional gap without requiring direct contact with the light emitting unit.
Solution Approach 2:
The solution moves from a single-plane shielding approach to a three-dimensional light control system. By placing the light absorbing material on the opposite surface of the substrate, the patent creates a multi-layer light management structure that addresses stray light from multiple angles and surfaces, effectively eliminating gaps in the shielding path.
2Object-affected harmful factors
If a pattern is used to cover the substrate surface to prevent stray light, then stray light suppression is improved, but the mounting area is enlarged, allowing heat to escape more easily during mounting
Solution Approach 1:
The light absorbing material is applied locally on the opposite surface of the substrate in the specific region where stray light would reach the light receiving unit. This localized application provides effective stray light suppression without requiring a full-coverage pattern, thereby maintaining thermal performance during mounting while achieving the desired optical function.
3Ease of manufacture
If gaps are left between the light emitting unit and light shielding member to ensure mountability, then manufacturing ease is improved, but light can pass through the gaps, reducing stray light suppression
Solution Approach 1:
The light absorbing material on the opposite surface acts as an intermediary that captures stray light regardless of gaps between the light emitting unit and the light shielding member. This allows gaps to be maintained for manufacturing ease while still achieving effective stray light suppression through the combined action of both shielding and absorbing materials.
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 effectively suppresses stray light, maintaining detection accuracy and ensuring component mountability by absorbing light on the substrate's opposite surface.
Implementation Method 1
a light absorbing material that absorbs light is formed on an opposite surface to the surface of the substrate on which the light emitting unit and the light receiving unit are mounted in order to suppress light emitted from the light emitting unit from being reflected by the opposite surface and reaching the light receiving unit
Data Source
AI summary
An optical sensor includes a light emitting unit configured to emit light toward an irradiated object, a light receiving unit configured to receive light that is emitted from the light emitting unit and then reflected by the irradiated object, and a substrate on which the light emitting unit and the light receiving unit are mounted on the same surface, wherein a light absorbing material that absorbs light is formed on an opposite surface to the surface of the substrate on which the light emitting unit and the light receiving unit are mounted in order to suppress light emitted from the light emitting unit from being reflected by the opposite surface and reaching the light receiving unit.