Double Action Elastic Hinge for Spectacles with Cam Slider
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Solution Overview
Problem
Existing elastic hinges for spectacles fail to reduce bulk in terms of height, width, and length while maintaining the sensations of traction and snap action, as size reduction leads to decreased traction values and emergence of the slider, and increasing spring rigidity increases bulk.
Innovation Solution
A double action elastic hinge with a convex-shaped first front surface and a cam region in the second articulation element, allowing maximum emergence of the slider in an intermediate condition, which cooperates with the cam region to enhance traction and snap action, achieving greater tension and return force with reduced bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the hinge bulk (height, width, length) is reduced, then the size of the spectacles is reduced, but the traction values and snap action sensation deteriorate
Solution Approach 1:
The first front surface is given a convex shaped profile with a protruding region, and the second front surface has a corresponding concavity. This curved geometry allows the cam region to effectively convert rotational motion into linear slider emergence, maximizing traction force within a compact volume. The curvature enables better force transmission without increasing hinge bulk.
Solution Approach 2:
The invention exploits the third dimension by creating an intermediate unstable condition where the slider emerges maximally from the box-like body. This intermediate position, achieved through the cam profile geometry, allows the spring to be pre-compressed to a greater extent, thereby increasing traction force without increasing the overall hinge dimensions. The distance variations occur along the axis of slider movement, optimizing force in a compact space.
2Force
If the spring rigidity is increased to maintain traction sensation, then the traction force is improved, but the hinge bulk increases
Solution Approach 1:
The invention creates a dynamic intermediate unstable condition where the slider position varies continuously with the hinge angle. The cam profile is designed so that at the intermediate position, the distance between the front plane and pivoting center is maximized, causing maximum slider emergence and spring compression. This dynamic geometry allows a softer spring to generate the same peak traction force as a stiffer spring would in a traditional design, reducing hinge bulk.
Solution Approach 2:
The invention changes the geometric parameters of the cam profile and box-like body to create an intermediate unstable equilibrium position. By adjusting the convex profile dimensions and the cam region geometry, the slider emergence distance is optimized to maximize spring pre-compression at the intermediate position. This parameter optimization allows reduced spring rigidity while maintaining traction force, thereby reducing hinge bulk.
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 hinge achieves greater extraction travel and tension, maintaining or improving the sensations of traction and snap action, with reduced bulk, as the maximum traction corresponds to the actual work between the surfaces, and distances vary along the axis of movement, enhancing the snap action effectiveness.
Implementation Method 1
a first articulation element is associated with the temple and by a slider elastically sliding inside the box-like body
Implementation Method 2
the spring is assembled already compressed (about 1 mm) to confer upon it most of the preloading
Implementation Method 3
the second articulation element is shaped with a cam profile, which cooperates with the front plane of the box-like body, to determine the snap action of the hinge
Data Source
Figure 1~4
Figure 5~8a
Figure 9~12
AI summary
A double action elastic hinge (10) for spectacles, which comprises, associated with the temple (12, 112) and the lug (14) of the spectacles, two articulation elements (16, 116, 216; 18) reciprocally hinged to allow the articulation of the temple (12, 212) with respect to the lug (14) between the open and closed positions, of which a first articulation element (16, 116, 216) comprises a box-like body (22, 122, 222, 322) which has a first front surface (34, 134, 234, 334) and inside which an elastic slider (26) is slidingly housed, and a second articulation element (18) constrained to the elastic slider (26) and which has a second shaped front surface (36) with a cam region (44, 144) which is able to slide on said first front surface (34, 134, 234, 334). An intermediate condition is provided in the movement of the temple (12, 112) and lug (14) in which the cam region (44, 144) determines a maximum emergence (A2) of the elastic slider (26) from the box-like body (22, 122, 222, 322). The first front surface (34, 134, 234, 334) has a convex shaped profile with a protruding region (42, 42a, 142, 242, 342) toward the outside of the box-like body (26). The second front region (36) is shaped in a manner mating with the first front surface (34, 134, 234, 334) so as to define a concavity (48) delimited on one side by the cam region (44, 144) and inside which the protruding region (42, 42a, 142, 242, 342) is located in the stable condition in which the temple (12, 212) is open with respect to the lug (14).