Lens Apparatus Radial Backlash Reduction via Spherical Intermediary
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Solution Overview
Problem
Existing lens apparatuses with helicoid mechanisms suffer from durability issues due to local abrasion and lubricant loss, and attitude changes of optical elements caused by uneven force distributions, particularly when using urging structures that directly contact helicoid screws or change relative to the centroid position.
Innovation Solution
A lens apparatus design featuring a first barrel member with an inner helicoid screw, a second barrel member with an outer helicoid screw, and an urging member, such as plate springs or a coil spring and spherical member, that applies a consistent urging force in a radial direction without direct contact with the helicoid screws, reducing backlash and maintaining a stable force balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the screw portion of the helicoid is directly urged by an elastic member, then the radial backlash is reduced, but local abrasion of the screw portion and lubricant loss occur, reducing durability
Solution Approach 1:
A spherical urging member is introduced as an intermediary between the elastic member and the helicoid screw. The spherical member contacts the screw portion and transmits the urging force, preventing direct contact between the elastic member and the screw. This intermediary structure protects the screw from local abrasion and lubricant loss while maintaining the backlash reduction effect.
2Device complexity
If the urging position is fixed on the male helicoid, then the structure is simple, but attitude change of the optical element occurs due to change in balanced state of forces during movement
Solution Approach 1:
The urging member is designed to be movable relative to the male helicoid along the optical axis, rather than being fixed. This dynamic configuration allows the urging position to adjust automatically during movement, maintaining a balanced state of forces and preventing attitude change of the optical element while keeping the overall structure relatively simple.
3Ease of operation
If a linear guide mechanism is provided inside the male helicoid to limit rotation, then rotation is constrained, but attitude change occurs due to change in balanced state of forces and partial contact of the urging member edge
Solution Approach 1:
The urging member is designed with a spherical surface instead of a flat or edged surface. The spherical shape ensures continuous contact with the male helicoid during movement, avoiding partial contact of edges that causes instability. The curved surface distributes the urging force more evenly, preventing attitude change while maintaining rotation constraint.
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
This design enhances durability by preventing local abrasion and lubricant loss, reduces optical element attitude changes, and maintains stability of optical performance by consistently applying urging forces that counteract backlash and gravity, ensuring smooth focusing operations.
Implementation Method 1
an urging member configured to urge the second helicoid screw against the first helicoid screw in a direction of a diameter of the first barrel member
Data Source
AI summary
A lens apparatus includes a first barrel member including a first helicoid screw on an inner surface included therein, a second barrel member including a second helicoid screw, screwed with the first helicoid screw, on an outer surface included therein, the second barrel member being movable along a direction of an axis of the first barrel member, an urging member configured to urge the second helicoid screw against the first helicoid screw in a direction of a diameter of the first barrel member, and a third barrel member including an outer surface which has a diameter smaller than a diameter of the second helicoid screw. The urging member is held by the second barrel member inside the second barrel member, and is in contact with the outer surface of the third barrel member.