Disappearance-style notebook

The retractable writing instrument addresses tip wobbling by using an annular member with notches and a guide surface, combined with a coil spring, for secure tip grip and improved operational stability.

JP7875738B2Active Publication Date: 2026-06-18PILOT PEN CO LTD
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Patent Information

Application Number
JP2022099128
Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Filing Date
2022-06-20
Publication Date
2026-06-18
Estimated Expiration
2042-06-20

AI Technical Summary

Technical Problem

Existing retractable writing instruments face issues with tip wobbling during use, requiring high dimensional accuracy and precision in component interactions, which complicates assembly and increases the risk of malfunctions and user discomfort.

Method used

A retractable writing instrument design featuring an annular member with notches and a guide surface that allows the inner diameter to shrink upon load application, coupled with a coil spring for relative movement, ensuring secure tip grip without looseness and reducing the risk of malfunctions.

Benefits of technology

The design provides stable writing feel by preventing tip wobble and minimizing assembly complexities, ensuring smooth operation and reduced risk of malfunctions.

✦ Generated by Eureka AI based on patent content.

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Abstract

To provide a retractable writing instrument which prevents rattling of a tip in writing and provides stable writing feeling, and is less susceptible to an actuation failure.SOLUTION: A retractable writing instrument includes a barrel having an opening in a front end thereof, a tip holder which can move in an axial direction of the barrel, a tip which can retract along with a movement of the tip holder, an annular member which is fitted in an inner periphery of the opening of the barrel with a play therebetween and can move in the axial direction, and an elastic member which can connect the tip holder and the annular member to each other with their relative movement allowed. An abutment surface tapered toward a front end is formed in at least part of an outer periphery of the annular member. A cutout is formed in part of the annular member. The annular member is configured such that when receiving a load on the abutment surface, an inner diameter of the annular member is reduced. A plurality of cutouts are disposed with equal distances therebetween in a circumferential direction of the annular member. The abutment surface is provided such that it protrudes radially outward in each of intermediate positions of two adjacent cutouts in a circumferential direction of the cutouts, as seen from the circumferential direction.SELECTED DRAWING: Figure 3
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Citation Information

Patent Citations

  • Anti-shake device for writing tip

    JP1993085683U

  • Writing tip shake prevention device

    JP1993093884U

  • Retracting and extending type writing utensil

    JP2000043478A

  • Writing utensil

    JP2013220602A

  • Writing instrument

    JP2013223931A