Lens Barrel with Stepped Front and Rear Sections for Optical Axis Alignment
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Solution Overview
Problem
The challenge lies in achieving high accuracy and stability in the formation of a plastic lens barrel for projectors with a wide zoom lens, particularly when the entire length of the lens exceeds 150 mm, as existing methods struggle to secure optical axis accuracy and require costly adjustments due to the significant diameter difference between the front and rear lenses, leading to increased time and costs.
Innovation Solution
The solution involves a plastic lens barrel design where the front and rear barrels are formed with specific reference and adjustment faces, allowing for precise alignment and adjustment of the optical axis, enabling accurate positioning and tilt correction without increasing costs, by dividing the barrel into two portions with a step and utilizing these faces to adjust the distance and tilt between the lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the barrel is made as a single piece with uniform diameter, then the manufacturing process is simple, but it is difficult to secure optical axis accuracy when the entire length exceeds 150 mm
Solution Approach 1:
The barrel is divided into a front barrel portion and a rear barrel portion with different diameters. The front barrel has a larger diameter to accommodate the super-wide angle lens, while the rear barrel has a smaller diameter for the zoom lens group. This segmentation allows each portion to be formed with appropriate precision for its specific function while maintaining overall manufacturing feasibility.
2Volume of moving object
If the barrel diameter is reduced to decrease size, then the overall dimensions are reduced, but the front group lens diameter must increase due to super-wide angle requirements, creating a step in the barrel
Solution Approach 1:
The barrel is segmented into front and rear portions with different diameters. The front barrel portion has a larger diameter suitable for the super-wide angle lens, while the rear barrel portion has a smaller diameter for the zoom lens group. This segmentation resolves the conflict between size reduction and optical requirements by allowing each section to have the appropriate diameter for its function.
Solution Approach 2:
Different portions of the barrel have different diameters tailored to their specific functions. The front portion has a larger diameter for the super-wide angle lens while the rear portion has a smaller diameter for the zoom lens group. This local differentiation optimizes both size and optical performance without creating formation instability.
3Manufacturing precision
If adjustment mechanisms are added to correct optical axis tilt, then optical accuracy is improved, but costs and time for attachment and adjustment increase
Solution Approach 1:
The front lens is pre-adjusted and fixed at the correct position and tilt angle during the barrel formation process itself. Reference faces are incorporated into the barrel structure to enable this preliminary adjustment, eliminating the need for complex post-assembly adjustment mechanisms and reducing both cost and complexity.
Data Source
AI summary
A lens barrel capable of forming high-accuracy barrel body and simply adjusting a tilt and a position in an optical axis direction without using dedicated portions is provided. The lens barrel includes a front barrel and a rear barrel. An inner diameter of a portion, containing a focus lens of the front barrel, is 1.15 times or more as large as an inner diameter of a portion containing a zoom lens of the rear barrel. The rear barrel and the front barrel are coupled by a coupling screw. A convex portion has an adjustment face for adjusting a distance between the focus lens and the zoom lens and is formed on a coupling face of the front barrel. A convex portion includes a reference face serving as a reception portion and is formed on the rear barrel.