Retractable Leash Length Control via Switch-Channel Interaction
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Solution Overview
Problem
Conventional retractable leashes lack a mechanism to shorten the leash length without compromising retractability, leading to accumulation of excess line and potential hazards such as tripping or tangling, which reduces user control and safety, especially in hazardous environments.
Innovation Solution
A length control system comprising a spool with opposing parallel surfaces, an extendable and retractable main line, and a switch that interacts with a channel to restrict extension but not retraction, allowing for adjustable leash length without affecting the retractable nature of the leash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manually actuated brake mechanism is used to shorten the leash length, then the user has more control over the pet, but the retractable nature of the device is eliminated and excess line accumulates
Solution Approach 1:
The patent applies a dynamic length control system where the switch can be moved between multiple positions (first position allowing full extension, second position limiting extension) without permanently locking the mechanism. This allows the leash to remain dynamically retractable while providing user-adjustable length control, resolving the contradiction between control and retractability.
Solution Approach 2:
The patent changes the parameter of extension length by using a switch with multiple positions that alter the effective length of the channel. In the first position, the channel allows full line extension; in the second position, it restricts extension to a shorter length. This parameter change enables controlled length adjustment while preserving retractability.
2Ease of operation
If the brake mechanism is locked to fix the wind-up spool, then the leash length is fixed for user convenience, but excess line accumulates creating tripping hazards
Solution Approach 1:
The switch mechanism is designed to be movable rather than locked, allowing the user to adjust between different extension lengths dynamically. This prevents the accumulation of excess line that would occur with a locked brake mechanism, thereby eliminating tripping hazards while maintaining ease of length control.
Solution Approach 2:
The channel acts as an intermediary element between the switch and the main line. The switch position controls the effective length of the channel, which in turn limits the amount of line that can extend. This intermediary mechanism provides precise length control without the need for complete locking, preventing excess line accumulation.
3Ease of operation
If the wind-up spool is frozen to a set length, then the user can maintain constant pressure without fatigue, but the retractable functionality is lost
Solution Approach 1:
The patent replaces the static frozen spool mechanism with a dynamic switch-controlled channel system. The switch can be positioned to allow full extension or limit extension, but unlike a frozen spool, the channel system maintains the ability to retract line in both positions. This preserves adaptability while reducing the need for constant user pressure.
Solution Approach 2:
The channel is pre-configured with specific geometries corresponding to different switch positions, establishing predetermined extension limits. This preliminary configuration allows the system to maintain desired lengths without continuous user intervention, while still preserving full retractability through the wind-up spool mechanism.
Data Source
AI summary
A retractable leash device (e.g., for pets, children, or the like) having a length control system for limiting the extendable length of a main line is provided. The device includes a cover plate mounted on a wind-up spool and having at least one ridged channel that interacts with a length control switch during line extension to control the extendable length of the main line while simultaneously maintaining the retractability of the main line.