Eyewear Strap Adjustment Mechanism With Lateral Pawl Release
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Solution Overview
Problem
Existing eyewear strap adjustment mechanisms are difficult to operate, often requiring significant force and causing discomfort due to button placement that depresses towards the user's head, and are inconvenient due to the need for precise finger and thumb coordination.
Innovation Solution
A strap adjustment mechanism featuring a pawl and engagement member that allows for lateral movement, actuated by a single button press, which lifts the pawl away from the strap to disengage it, providing a more robust and convenient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a button is depressed in a direction towards the user's head to disengage the strap, then the strap can be adjusted, but it causes discomfort by pushing into the user's head
Solution Approach 1:
Instead of depressing the button towards the user's head (inward direction), the button is configured to be depressed away from the user's head (outward direction). This reverses the actuation direction to eliminate the harmful effect of pushing into the user's head while maintaining the strap disengagement function.
Solution Approach 2:
The button actuation is moved from a horizontal dimension (towards/away from head) to a vertical or lateral dimension. The button can be depressed vertically or laterally, changing the dimension of actuation to avoid the harmful horizontal inward movement while preserving the mechanical advantage for strap release.
2Object-affected harmful factors
If buttons are arranged at upper and lower sides requiring pinching together to disengage the strap, then discomfort is reduced, but the mechanism becomes inconvenient requiring accurate finger and thumb positioning
Solution Approach 1:
Instead of requiring two separate buttons to be pinched together, the mechanism uses a single button that controls the pawl release. This merges the two-button operation into one, eliminating the need for precise finger and thumb coordination while maintaining comfort by avoiding headward actuation.
Solution Approach 2:
The complex two-button pinching mechanism is extracted and replaced with a simpler single-button actuation system. The essential function of releasing the pawl is extracted and achieved through a more convenient single-point actuation that doesn't require coordinated bimanual or bifinger operation.
3Ease of operation
If significant force is applied to operate the adjustment mechanism, then the strap can be disengaged, but the mechanism becomes difficult to operate
Solution Approach 1:
The button is configured with a curved or sloped pressing surface that provides mechanical advantage. The curved geometry allows the user's finger to apply force more effectively, converting downward finger pressure into the lateral or rotational motion needed to release the pawl, thereby reducing the overall force required from the user.
Solution Approach 2:
The button acts as an intermediary lever between the user's finger and the pawl release mechanism. This intermediate element amplifies the user's input force and directs it efficiently to disengage the pawl from the strap, reducing the effort the user must exert compared to direct pawl manipulation.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A strap adjustment mechanism (10) for eyewear (12) that includes a strap (14) for securing the eyewear to a user's head, the adjustment mechanism (10) comprising a body (15) having an elongate shaft (16) about which a head strap (14) can extend, the elongate extension of the shaft defining a longitudinal direction; a pawl (20) comprising a mounting portion (21) that movably mounts the pawl (20) to the body (15) and a cam (27) surface facing the body, the pawl (20) extending in a lateral direction towards the shaft from the mounting portion (21) to a free end (22), an engagement member (25) moveable between the pawl (20) and the body (15), the engagement member (25) and cam surface (27) of the pawl (20) configured to cooperate such that lateral movement of the engagement member (25) moves the free end (22) of the pawl (20) between an engaged position in which the free end (22) is able to engage a strap (14) when extending about the shaft (16); and a disengaged position in which the free end (22) is lifted away from the shaft (16) so as to be disengaged from a strap (14) when extending about the shaft (16).