Lens-Free Rain Sensor Module With Transparent Thermal Coupling
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Solution Overview
Problem
Conventional automobile rain and temperature sensors are costly due to the use of collimating and focusing lenses, and require significant modifications for different application environments, while windshield temperature sensors have mechanical components that are expensive, space-intensive, and prone to mechanical failure.
Innovation Solution
A rain and temperature sensing module with a housing containing a printed circuit board, a light emitter, a light receiver, and a temperature sensing element, where a transparent compound fills the space between the board and a cover plate, providing refractive index matching for lens-free optical coupling and thermal conductivity, eliminating the need for mechanical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If collimating and focusing lenses are used in rain sensors, then optical performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the collimating and focusing lenses from the sensor system entirely. Instead of using optical lenses to shape and direct light, the invention uses a transparent compound with specific refractive index properties that naturally guides light from the LED to the photodetector without requiring additional optical components, thereby eliminating manufacturing costs associated with lenses while maintaining functional performance
Solution Approach 2:
The transparent compound serves multiple functions simultaneously: it acts as an optical medium with appropriate refractive index for light guidance, provides mechanical support and alignment, and enables compact integration of all sensor components within the housing without requiring separate lens assemblies
2Measurement precision
If collimating and focusing lenses are used in rain sensors, then optical performance is improved, but device complexity increases
Solution Approach 1:
The patent eliminates the complex optical system comprising collimating lenses, focusing lenses, and associated mounting structures. The simplified design uses only the transparent compound medium to achieve light guidance, significantly reducing the number of components and assembly steps while maintaining the necessary optical functionality
Solution Approach 2:
The invention merges the optical medium function with the structural housing and component mounting functions into a single transparent compound material. This consolidation eliminates the need for separate lens components and their associated mounting hardware, reducing overall device complexity while achieving the required optical performance
3Measurement precision
If mechanical components are used in windshield temperature sensors, then temperature measurement is achieved, but reliability decreases due to mechanical failure
Solution Approach 1:
The patent replaces mechanical temperature sensing components (such as contact-based thermocouples or resistance temperature detectors requiring physical mounting) with an integrated temperature sensing element that is embedded within the transparent compound. This eliminates mechanical mounting requirements, flexible circuit boards, and spring-loaded contacts, thereby removing the primary sources of mechanical failure while maintaining accurate temperature measurement capability
4Measurement precision
If mechanical components are used in windshield temperature sensors, then temperature measurement is achieved, but manufacturing cost increases
Solution Approach 1:
The invention replaces expensive mechanical components including flexible circuit boards, spring-loaded mounting mechanisms, and precision mechanical assemblies with a simplified integrated design where the temperature sensing element is directly embedded in the transparent compound, significantly reducing bill of materials costs and assembly complexity
Solution Approach 2:
The patent combines the temperature sensing element with the transparent compound medium and housing structure into a single integrated assembly, eliminating the need for separate mechanical mounting components and reducing the overall part count, which directly reduces manufacturing costs while maintaining temperature measurement functionality
5Measurement precision
If mechanical components are used in windshield temperature sensors, then temperature measurement is achieved, but space requirements increase
Solution Approach 1:
The invention merges the temperature sensing element with the transparent compound medium and housing structure into a compact integrated assembly, eliminating the space required for separate mechanical mounting components, flexible circuit boards, and adjustment mechanisms, thereby significantly reducing the overall volume of the temperature sensor
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
The solution reduces manufacturing costs, allows for easier configuration changes without modifying the housing, and prevents mechanical failures, enabling efficient detection of rain and temperature with improved reliability and reduced space requirements.
Implementation Method 1
a transparent compound disposed within the housing and filling a space between the printed circuit board and the cover plate
Implementation Method 2
the compound provides a thermally conductive medium between the cover plate and the temperature sensing element
Data Source
AI summary
A rain and temperature sensing module including a housing having a cover plate formed of a transparent material, a printed circuit board disposed within the housing and having a light emitter, a light receiver, and a temperature sensing element disposed thereon, a transparent compound disposed within the housing and covering the light emitter, the light receiver, and the temperature sensing element, the transparent compound filling a space between the printed circuit board and the cover plate, wherein the transparent compound has a refractive index that is substantially equal to a refractive index of the cover plate, and wherein the transparent compound provides a thermally conductive medium between the cover plate and the temperature sensing element.