Diopter Adjustment Using Asymmetric Thread Handedness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional diopter adjustments in optical devices, such as riflescopes, fail to effectively lock the diopter assembly at a desired position due to the use of right-handed threads, leading to unintended changes during recoil or adjustment, especially in 'fast focus' styles with reduced thread friction.
Innovation Solution
A diopter adjustment device featuring overlapping left-handed and right-handed threads on tubular members, with a stop nut having internal threads of opposite handedness to provide increased resistance and secure the diopter lens in place, preventing inadvertent movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If right-handed threads are used for the diopter barrel, eyeshell, and locknut, then the assembly is simple to manufacture and assemble, but the locknut is prone to moving along the diopter subassembly barrel when the diopter assembly is twisted clockwise, resulting in poor locking performance
Solution Approach 1:
The patent applies asymmetry by using left-handed threads for the locknut while the diopter barrel and eyeshell use right-handed threads. This asymmetric thread handedness creates differential rotational responses: when the diopter assembly is twisted clockwise for focusing, the locknut experiences increased thread friction and resistance that prevents it from rotating or moving along the barrel, thereby maintaining reliable locking performance while keeping the manufacturing process relatively simple.
2Speed
If fast focus threads with larger lead and greater helix angle are used, then the diopter adjustment speed is improved, but thread friction is reduced, making the locknut even more prone to movement and reducing stopping power
Solution Approach 1:
The patent resolves this contradiction by applying asymmetric thread handedness specifically to the locknut. The fast-focus right-handed threads on the diopter barrel maintain high adjustment speed with reduced friction, while the left-handed threads on the locknut create opposite-direction friction resistance. When the assembly is rotated clockwise for fast focusing, the left-handed locknut threads engage in a way that generates friction opposing the rotation direction, preventing the locknut from moving along the barrel despite the reduced friction of the fast-focus threads.
Solution Approach 2:
The patent applies inversion by reversing the thread handedness of the locknut relative to the diopter barrel and eyeshell. This inversion causes the locknut to respond differently to rotational forces: during clockwise rotation for focusing, the inverted (left-handed) threads create friction that resists locknut movement, while during counterclockwise rotation, the locknut can be easily unscrewed for adjustment. This inverted approach allows fast-focus threads to maintain speed while the inverted locknut threading provides the necessary friction-based locking stability.
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 provides enhanced resistance to inward movement of the diopter lens, ensuring a secure and stable diopter setting, even under recoil conditions, compared to conventional locking diopter adjustments.
Implementation Method 1
a first tubular member having external threads, including overlapping left-handed and right-handed threads. The first tubular member is threadably attached to a second tubular member having internal threads so that the internal threads of the second tubular member are mated with either the left-handed or right-handed external threads of the first tubular member
Implementation Method 2
A nut having internal threads that are of opposite handedness as the internal threads of the second tubular member is threaded onto the first tubular member, so that the internal threads of the nut are mated with the external threads of the first tubular member. The nut is rotatable to a selected diopter adjustment position whereat the nut bears against an end of the second tubular member to thereby stop further inward movement of the diopter lens and secure it in place. Because the internal threads of the nut and the second tubular member have opposite handedness, the nut provides greater resistance to inward movement of the diopter lens than conventional locking diopter adjustments.
Data Source
AI summary
A diopter adjustment device for an optical device such as a riflescope includes a first tubular member having overlapping left-handed and right-handed external threads, a second tubular member has internal threads mated with either the left-handed or right-handed external threads of the first tubular member, and a stop nut threaded onto the first tubular member via internal threads that are of opposite handedness as the internal threads of the second tubular member. A diopter lens is mounted in one of the first and second tubular members and movable therewith relative to the other of the first and second tubular members to adjust a diopter setting or focus of the optical device. Because the internal threads of the nut and the second tubular member have opposite handedness, the nut provides greater resistance to inward movement of the diopter lens than conventional locking diopter adjustments.