Optical Imager Assembly Stabilization for Thermal Focus Accuracy
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Solution Overview
Problem
Higher resolution cameras in automotive applications are sensitive to optical misalignment due to strain and deformations within the assembly, which can be exacerbated by thermal cycling, leading to image defocusing issues despite the use of mechanical fasteners and adhesives for alignment.
Innovation Solution
A method involving a two-step adhesive curing process where a first adhesive layer stabilizes the imager assembly before lens alignment, using heat curing to achieve maximum bond strength, and a second adhesive layer for precise optical alignment of the lens, ensuring positional accuracy and focus maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical fasteners and adhesives are used to secure the imager assembly, then the assembly is mechanically stable, but thermal cycling causes residual strains to flex the PCB and move the imager out of focus
Solution Approach 1:
The patent applies preliminary action by pre-stabilizing the imager assembly to the PCB using adhesive before performing optical alignment of the lens. This ensures the imager position is fixed and stable before the precision alignment process, preventing subsequent shifts during thermal cycling that would compromise focus.
Solution Approach 2:
The patent changes the physical state and bonding parameters of the adhesive by controlling curing temperature and time. The adhesive is cured at elevated temperatures (e.g., 80-150°C) for extended periods to achieve maximum bond strength and minimal residual stress, thereby stabilizing the imager position against thermal expansion and contraction during operation.
2Productivity
If adhesive is cured quickly to maintain productivity, then manufacturing efficiency increases, but the adhesive may not reach full bond strength and positional stability
Solution Approach 1:
The patent separates the adhesive application and curing process from the final optical assembly process. The adhesive is applied and partially cured in advance to establish a stable imager position, allowing subsequent lens alignment to be performed on a stabilized platform without waiting for complete adhesive cure.
Solution Approach 2:
The patent optimizes adhesive curing parameters by using elevated temperatures (80-150°C) and extended time periods to achieve complete cure and maximum bond strength. This ensures the adhesive reaches full mechanical properties while maintaining production efficiency through controlled thermal processing.
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 method effectively maintains image focus by stabilizing the imager assembly and preventing deformation caused by thermal cycling, enhancing the optical system's positional accuracy and image clarity in high-resolution camera assemblies.
Implementation Method 1
applying a first adhesive layer to a mating region of at least one of the circuit board and the support; and fastening the circuit board to the support using at least one fastener, wherein the first adhesive layer is compressed between the mating regions once the circuit board is fastened; curing the first adhesive layer for forming a stabilised imager assembly
Implementation Method 2
A method involving a two-step adhesive curing process where a first adhesive layer stabilizes the imager assembly before lens alignment, using heat curing to achieve maximum bond strength
Implementation Method 3
fixing a lens to the stabilised imager assembly using a second adhesive layer, wherein the step of fixing the lens includes positioning the lens on the support to align its focal plane with the imager and curing the second adhesive layer
Data Source
Figure 1
Figure 2
AI summary
Method of assembling an optical device in which a circuit board (1) is provided supporting an imager (10), and a support (4) is provided for supporting the circuit board (1). A first adhesive layer (9) is applied to a mating region (2,3) of at least one of the circuit board (1) and the support (4). The circuit board (1) is fixed to the support (4) using at least one fastener (11). The first adhesive layer (9) is compressed between the mating regions (2,3) once the circuit board (1) is fastened. The first adhesive layer (2) is then cured for forming a stabilised imager assembly (12). A lens (6) is then fixed to the stabilised imager assembly (12) using a second adhesive layer (8), where fixing includes positioning the lens (6) on the support (4) to align its focal plane with the imager (10) and then curing the second adhesive layer (8).