Expandable Writing Instrument Helix Cylinder Cam Mechanism
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Solution Overview
Problem
Existing expandable writing instruments face challenges in smoothly and effortlessly extending their writing tips from a compact closed position to an extended open position for comfortable use, particularly for individuals with larger fingers or those requiring ease of handling, as they often require complex mechanisms that are not efficiently described in prior patents.
Innovation Solution
The design incorporates a helix cylinder with a 360-degree closed loop track formed by 180 degrees of right and left-handed helices, a sloping wall with a 90-degree cutout, and a shuttle cam with specific surface features that allow for smooth axial and rotational movement, enabling effortless extension and retraction of the writing tip through a cam mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the writing instrument is made compact for storage and carry, then it occupies less space and is easier to carry, but it becomes difficult to hold and use for many people including the elderly, children, and people with large fingers
Solution Approach 1:
The writing instrument incorporates an expandable mechanism that allows the barrel to transition between a compact retracted state and an extended writing state. The barrel includes a first section and a second section that can be positioned at different distances from each other, creating an intermediate expanded state that provides ergonomic handling while maintaining compact storage capability.
2Ease of operation
If an expandable mechanism is added to extend the writing tip, then the writing comfort is improved, but the device complexity increases
Solution Approach 1:
The expandable mechanism utilizes a nested structure where the second barrel section is positioned within or alongside the first barrel section. The cam mechanism is integrated within the barrel assembly, with the cam groove formed directly in the first barrel section. This nesting approach allows the expansion mechanism to be compact when retracted while providing smooth expansion when needed, without adding excessive external complexity.
3Extent of automation
If a cam mechanism is used to extend and retract the writing tip, then automatic extension is achieved, but the mechanism becomes more complex and difficult to manufacture
Solution Approach 1:
The cam groove is formed directly in the first barrel section, merging the cam mechanism with the barrel structure itself rather than requiring a separate cam component. The second barrel section functions as both a structural element and a follower that engages with the cam groove. This integration reduces the number of discrete parts, simplifies manufacturing processes, and eliminates the need for separate cam assemblies while still achieving automatic tip extension through the cam-follower interaction.
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 solution allows for a writing instrument that can automatically extend its writing tip smoothly and effortlessly from a compact position to an open position, accommodating users with larger fingers and providing comfortable writing experiences while maintaining a compact storage form.
Implementation Method 1
a cam mechanism, the cam mechanism having a cam groove formed integrally with the first barrel section
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
An expandable writing instrument has a writing end body section and a rear body section mounted to the writing end body section for relative axial and non-rotational movement between an extended position with the rear body section spaced away from the writing end body section, and a retracted position with the rear body section closer to the writing end body section. A spring in the writing end body section biases the cartridge upwardly. A helix cylinder is mounted for rotation and axial movement in the rear body section with a peg of the rear body section sliding in a track of the helix cylinder. The track is a closed loop with left and right hand helixes so that axial movement of the rear body section causes rotation of the helix cylinder continuously in one rotational direction. A shuttle receives a cartridge body and is mounted for axial movement in the helix cylinder. A shuttle cam on the shuttle is mounted for axial non- rotational movement to the writing end body section. Shuttle cam surfaces slidably engage cam surfaces of the helix cylinder and the cam surfaces include a high point that engages a flat portion of another cam surface for moving the shuttle with rotation of the helix cylinder, to project a writing tip of a cartridge out of the bottom opening in the extended position.