Lens Alignment via PCB Cutouts and Guide Posts
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Solution Overview
Problem
Optical sensor packages face stability issues due to misalignment and rotation of the lens with respect to the Printed Circuit Board (PCB), leading to instability in both vertical and horizontal directions.
Innovation Solution
The design incorporates a lens with protrusions that correspond to cut-out sections on the PCB, allowing for alignment and locking in multiple directions, using guide posts or snap features to secure the lens to both the PCB and sensor, ensuring stability in all axes (x, y, z).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the lens is placed in a pocket of the base plate and aligned with the sensor via protrusion and depression, then the lens and sensor are aligned, but the lens is not aligned with the PCB allowing rotation in horizontal direction
Solution Approach 1:
The patent introduces guide posts as intermediary alignment features that extend from the PCB through cutouts in the lens holder to engage with corresponding features on the lens. These guide posts serve as mediators that simultaneously align the lens with both the sensor (via the existing protrusion-depression interface) and the PCB (via the guide post-cutoff engagement), thereby resolving the misalignment issue without compromising either alignment precision or structural stability.
Solution Approach 2:
The alignment system is segmented into multiple independent alignment features: vertical alignment is achieved through the sensor protrusion engaging with the lens depression, while horizontal alignment and rotational stability are achieved through the guide posts engaging with cutouts in the lens holder. This segmentation of alignment functions allows each feature to independently address specific alignment requirements without interfering with others.
2Length of stationary object
If the PCB is pressed down onto the base plate to set height, then the package height is defined, but the lens may rotate horizontally due to the opening size in the PCB
Solution Approach 1:
The guide posts are positioned asymmetrically relative to the lens center, with at least one guide post located off-center. This asymmetric arrangement creates a mechanical constraint that prevents rotational movement of the lens around the vertical axis, as rotation would cause the guide posts to collide with the edges of their respective cutouts. The asymmetric positioning transforms the previously free rotational degree of freedom into a constrained state.
Solution Approach 2:
The patent addresses the horizontal rotational instability by introducing alignment features that operate in the vertical dimension. The guide posts extend vertically from the PCB through the lens holder, creating vertical constraints that prevent horizontal rotation. This dimensional approach allows the lens to be firmly anchored in the horizontal plane through vertical engagement features.
3Stability of the object's composition
If multiple alignment features are added to prevent rotation and improve stability, then lens alignment and stability are improved, but the assembly process and structure become more complex
Solution Approach 1:
The guide posts serve multiple functions simultaneously: they act as alignment features during assembly, provide mechanical constraints to prevent rotation, and serve as structural support elements. By merging these multiple functions into a single integrated feature, the patent avoids the need for separate alignment pins, rotation preventers, and support structures, thereby reducing overall structural complexity while achieving enhanced stability.
Solution Approach 2:
The guide posts are designed as universal alignment and constraint features that work throughout the assembly process. The same guide post structure that facilitates initial alignment also provides ongoing rotational constraint and structural support. This multi-functionality eliminates the need for additional specialized components, reducing both structural and procedural complexity.
Data Source
AI summary
An optical package includes: a Printed Circuit Board (PCB) including a plurality of cut-out sections; a lens, including a first plurality of protrusions corresponding respectively to the plurality of cut-out sections, wherein the first plurality of protrusions includes three protrusions being guide posts, a first protrusion of the first plurality of protrusions is formed on a first side of the lens, and a second protrusion of the first plurality of protrusions is formed on a second side of the lens opposite to the first side, and when the lens is placed under the PCB, the first plurality of protrusions will pass through the cut-out sections; and a sensor for attaching on to the lens and the PCB.