Self-Retracting Knife Anti-Retraction Latch Bar
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Solution Overview
Problem
Traditional self-retracting utility knives require precise thumb or finger positioning to extend and retract the blade, which can be cumbersome and transfer pressure to the activating finger or thumb, especially during heavy cuts, and do not allow for easy partial blade exposure without risking damage to surrounding contents.
Innovation Solution
A self-retracting knife with a housing and blade carrier that includes an anti-retraction latch bar, allowing users to select a latching or non-latching position by applying light pressure, enabling the blade carrier to be extended and maintained in a fully extended or partially extended position, and featuring an extension limiter to adjust the blade exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thumb or finger pressure is used to extend the blade carrier against the spring force, then the blade can be extended for cutting, but the pressure is transferred to the activating finger or thumb during heavy cuts
Solution Approach 1:
A latch bar is introduced as an intermediary mechanism between the user's finger and the blade carrier. The latch bar engages with the blade carrier to hold it in the extended position, allowing the user to apply only light pressure to maintain blade exposure rather than continuous pressure during cutting operations.
2Measurement precision
If precise thumb or finger positioning is required to control blade extension, then the blade can be held at the desired extension level, but the operation becomes cumbersome
Solution Approach 1:
The latch bar mechanism allows the blade carrier to maintain its extended position automatically once engaged, without requiring continuous precise positioning by the user. The system serves itself by holding the blade in place through the latch engagement rather than relying on sustained finger pressure and positioning.
3Strength
If the blade carrier is allowed to extend fully for heavy cuts, then cutting capability is maximized, but the blade may extend too far and risk damage to surrounding contents
Solution Approach 1:
The latch bar can be positioned at different engagement points along the blade carrier's travel path, allowing dynamic adjustment of the blade extension distance. This enables the user to select between full extension for heavy cuts or partial extension for delicate work, adapting the blade exposure to the specific task requirements.
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 allows for easier and safer blade extension and retraction, reducing pressure on the activating finger or thumb, enabling precise control over blade exposure, and allowing for partial blade exposure without risking damage to contents, making the knife more user-friendly and versatile.
Implementation Method 1
A self-retracting utility knife usually includes a tension spring that pulls the blade carrier into the handle to keep the blade fully retracted.
Data Source
AI summary
A self-retracting knife includes a housing having a forward end defining a blade aperture, and a blade carrier supports a removable knife blade and is movable within the housing from a fully extended position with the blade projecting from the blade aperture and a fully retracted position by a tension spring. An anti-retraction latch member is supported by the housing and is movable with finger pressure to a position that stops the blade carrier from fully retracting so that the knife blade is partially extended through the blade aperture. In other embodiments, the blade carrier extends through a carrier aperture at the opposite end of the housing for extending the blade carrier, and an adjustable extension limiter also extends through the carrier aperture for limiting forward movement of the blade carrier and projection of the blade through the blade aperture.