Slit Cam Follower Structure for Lens Barrel Backlash Control
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Solution Overview
Problem
The cam mechanism in lens devices experiences backlash and accuracy issues due to elastic deformation of cam followers, which affects contact pressure and mounting accuracy, especially when fitted to grooves with varying machining accuracy.
Innovation Solution
A cam follower with a hollow shape, featuring a press-fitting portion, arc-shaped contact surfaces, and strategically positioned first and second slits that reduce deformation influence between grooves, allowing for efficient elasticity use and stable operation while minimizing the impact of machining accuracy variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cam follower is made elastically deformable by slits to prevent backlash, then contact pressure with grooves is improved, but deformation of one fitting portion affects other fitting portions and press-fitting accuracy
Solution Approach 1:
The cam follower is divided into multiple independent elastic regions by introducing both first slits (axial direction) and second slits (radial direction). This segmentation isolates the deformation of each fitting portion, preventing deformation propagation between different contact regions while maintaining overall structural integrity for accurate press-fitting.
Solution Approach 2:
Different regions of the cam follower are given different structural characteristics through strategically positioned slits. The regions near groove contact surfaces have enhanced elasticity via slits to ensure proper contact pressure, while the press-fitting region maintains higher rigidity to preserve mounting accuracy. This local differentiation allows each region to optimize its function independently.
2Manufacturing precision
If the cam follower is made rigid to maintain mounting accuracy, then press-fitting precision is improved, but backlash occurs between cam follower and grooves
Solution Approach 1:
The cam follower structure is segmented into rigid and elastic zones through the strategic placement of first and second slits. The press-fitting portion remains rigid to ensure accurate mounting, while separate elastic zones near the groove contact surfaces accommodate backlash prevention through controlled deformation, isolating the two functions spatially.
Solution Approach 2:
The cam follower exhibits locally differentiated mechanical properties: high rigidity in the press-fitting region for accurate mounting, and controlled elasticity in the groove-contact regions for backlash prevention. This local quality differentiation resolves the contradiction by allowing each region to optimize its mechanical behavior independently.
3Measurement precision
If machining accuracy of grooves is increased to reduce backlash, then contact precision is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The cam follower's elastic deformation capability allows it to self-adjust and compensate for groove machining variations. The slits enable the structure to deform elastically, automatically adapting to minor groove dimension tolerances without requiring high-precision groove machining, thereby reducing manufacturing costs while maintaining contact precision.
Solution Approach 2:
The invention changes the mechanical parameter of the cam follower from rigid to elastically deformable through the introduction of slits. This parameter change allows the system to tolerate wider groove machining tolerances while maintaining proper contact pressure and precision, eliminating the need for costly high-precision groove manufacturing.
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 prevents backlash and ensures smooth operation of the lens barrel, maintaining accurate contact pressure and mounting precision even with variations in groove machining accuracy.
Implementation Method 1
a method of allowing a cam follower to be elastically deformable in a radial direction and making the cam follower be in pressure contact with the inner wall surface of each groove
Data Source
AI summary
A lens barrel includes a stationary barrel, a rotary barrel, and a movable barrel. The movable barrel includes a cam follower fitted to a straight groove in the stationary barrel and a cam groove in the rotary barrel. The surface of the cam follower to be in contact with the inner wall surface of the cam groove and the surface of the cam follower to be in contact with the inner wall surface of the straight groove have an arc shape convex toward the outside, and the cam follower is in point contact with the inner wall surfaces of the cam groove and the straight groove. The cam follower includes a first slit that is cut in from the distal end toward a proximal end thereof in parallel to an axis and a second slitcut in from an outer peripheral portion of the cam follower toward an inner peripheral portion.