Near-Infrared Sensor Cover With Molded Asperities
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Solution Overview
Problem
Existing near-infrared sensor covers require a troublesome operation to attach a reflection suppression layer to the heater film, which increases manufacturing complexity and reduces detection accuracy due to increased reflection and absorption of near-infrared rays.
Innovation Solution
The near-infrared sensor cover incorporates a reflection suppression structure with asperities on the base, which reduces reflection without the need for a separate reflection suppression layer, using a moth-eye structure with inclined surfaces and a hydrophilization film to enhance transmissivity and reduce fogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heater film and reflection suppression layer are added to the cover body, then snow melting function and reflection reduction are achieved, but the manufacturing process becomes troublesome and complex
Solution Approach 1:
The heater unit is integrated directly into the base of the cover body, merging the heating function with the structural component. The reflection suppression structure is formed as asperities on the rear surface of the base, combining the reflection suppression function with the base structure itself, eliminating the need for separate heater film and reflection suppression layer attachments.
Solution Approach 2:
The base of the cover body serves multiple functions: it provides structural support, integrates the heater unit for snow melting, and incorporates the reflection suppression structure to reduce near-infrared ray reflection. This multi-functionality reduces the number of separate components and simplifies manufacturing.
2Reliability
If multiple layers (heater film and reflection suppression layer) are added to the cover body, then snow melting and reflection reduction functions are achieved, but near-infrared ray transmission is hindered due to increased absorption and reflection
Solution Approach 1:
The reflection suppression structure is applied locally on the rear surface of the base where near-infrared rays are radiated, rather than adding multiple layers throughout the entire cover body. This localized approach reduces reflection without significantly increasing absorption or blocking near-infrared transmission.
Solution Approach 2:
Instead of using a separate reflection suppression layer made of dielectric substances requiring vacuum deposition or sputtering, the patent copies the reflection suppression function by forming asperities directly on the plastic base material through molding, achieving similar optical effects with simpler manufacturing.
3Manufacturing precision
If a reflection suppression layer is attached to the heater film, then reflection of near-infrared rays is reduced, but manufacturing complexity and costs increase
Solution Approach 1:
The reflection suppression structure is formed in advance as part of the base molding process, before assembly. The asperities are created on the rear surface of the base during the initial plastic molding, eliminating the need for subsequent attachment operations of separate reflection suppression layers.
Solution Approach 2:
The base structure itself provides the reflection suppression function through its molded asperities, making the base self-sufficient for both structural and optical functions. This eliminates the need for additional components and attachment processes, simplifying manufacturing while maintaining precision.
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 achieves high transmissivity (>60%) and low reflectance (<10%) for near-infrared rays, improving detection accuracy and eliminating the need for a separate reflection suppression layer, while also simplifying the manufacturing process and reducing the likelihood of peeling issues.
Implementation Method 1
The heater unit includes a wire-like heating element. The heating element is configured to generate heat when energized
Implementation Method 2
The base includes a rear portion that includes a rear surface of the base in the transmission direction. In the rear portion of the base, at least part of a section that is different from a section in which the heater unit is provided is formed by a reflection suppression structure including asperities. The asperities include a reflection suppression surface that is inclined relative to the transmission direction and reduces reflection of the near-infrared rays
Data Source
AI summary
A near-infrared sensor cover includes a cover body having transmissiveness to near-infrared rays. The cover body includes a base and a heater unit. The heater unit is arranged rearward of the base in a transmission direction of the near-infrared rays and includes a wire-like heating element. The heating element is configured to generate heat when energized. The base includes a rear portion that includes a rear surface of the base in the transmission direction. In the rear portion of the base, at least part of a section that is different from a section in which the heater unit is provided is formed by a reflection suppression structure including asperities. The asperities include a reflection suppression surface that is inclined relative to the transmission direction and reduces reflection of the near-infrared rays.