Vehicular Camera Vacuum Lens Assembly Condensation Prevention
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Solution Overview
Problem
Vehicular cameras often fail to prevent condensation on lens elements due to temperature differentials, leading to impaired image capture in harsh environmental conditions, as existing camera housings do not effectively seal out moisture and maintain internal temperatures above the dew point.
Innovation Solution
A vehicular camera design featuring a vacuum space between the outer and inner lens elements, along with a plasma hydrophilic coating on the inner lens surface, to thermally isolate and prevent condensation, while optionally using a heating system to maintain the inner lens element above the dew point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional camera housing is used without vacuum sealing, then the device complexity is low, but condensation forms on the inner lens element due to temperature differentials between the outer and inner lens surfaces
Solution Approach 1:
A vacuum space is introduced as an intermediary thermal insulation layer between the outer lens element (exposed to cold environment) and the inner lens element (inside the housing). This vacuum barrier prevents direct thermal conduction, keeping the inner lens element temperature above the dew point and preventing condensation formation.
Solution Approach 2:
The vacuum space creates an inert (vacuum) environment between the lens elements, eliminating air molecules that would otherwise conduct heat from the cold outer lens to the inner lens. This inert barrier maintains thermal isolation and prevents the temperature differential that causes condensation.
2Reliability
If the inner lens element is thermally isolated from the outer lens element, then condensation is prevented on the inner surface, but the manufacturing precision required to create and maintain the vacuum space increases
Solution Approach 1:
A thin vacuum seal barrier (such as a membrane or thin-walled structure) is used to create the vacuum space between the lens elements. This thin film approach achieves effective thermal isolation while minimizing the complexity of manufacturing and maintaining the vacuum, compared to rigid heavy-duty insulation structures.
3Reliability
If the camera housing seals out moisture effectively, then condensation is eliminated, but the ease of manufacture decreases due to additional sealing requirements
Solution Approach 1:
The vacuum sealing function and moisture sealing function are merged into a single integrated structure. The vacuum barrier simultaneously serves as both the thermal insulation layer and the moisture seal, eliminating the need for separate sealing components and simplifying the overall manufacturing process.
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 effectively reduces or eliminates condensation on the inner lens elements, ensuring clear image capture by maintaining the inner lens element warmer than the dew point and reducing moisture intrusion, thereby enhancing the camera's operational reliability in varying environmental conditions.
Implementation Method 1
The vacuum space thermally insulates an outer surface of the outer lens element from an inner surface of the inner lens element to reduce or eliminate condensation that may form at the inner surface of the inner lens element
Data Source
AI summary
A vehicular camera assembly includes a lens barrel accommodating at least an outer lens element and an inner lens element. An imager printed circuit board (imager PCB) includes an imager disposed at a side. The lens barrel is disposed at the housing such that the imager is aligned with the inner lens element and the outer lens element, with the inner lens element disposed closer to the imager than the outer lens element. A vacuum exists in a space between the outer lens element and the inner lens element to thermally insulate an outer surface of the outer lens element from an inner surface of the inner lens element. Light passing through the outer lens element, the vacuum, and the inner lens element is imaged by the imager.