A writing instrument and a pen tip part include: a pen tip which includes a writing portion and has a directional specification for writing of the writing portion; a cylindrical inner cylinder which fixes the pen tip; a cylindrical outer cylinder into which the inner cylinder can be inserted and which includes a finger guide portion on an outer peripheral surface; and a fixture which fixes the outer cylinder to the inner cylinder.

A writing instrument that includes a barrel extending along a longitudinal axis (A) and a tip mounted at the front of the barrel, further including a protective sleeve for the tip, the sleeve being mounted coaxially on the barrel and movable relative to the barrel between a protective position where it covers the tip and a retracted position where it exposes the tip to allow writing. The sleeve includes an inner wall which includes a helical cam engaging with a guide element formed on the barrel so that the sleeve is movable in translation combined with rotation.

An apparatus including a body configured to house a writing tool therein and a sharpener connected to the body. The sharpener is configured to allow a user to sharpen a knife by gripping the body and sliding the knife on the sharpener.

The adaptation of a pocket-size pen for use by a person is provided. The pen includes a cap with internally configured male threads, and a body. The body includes a barrel with externally configured and spaced apart first set of female threads, and second set of female threads. The barrel is hollow inside with a top opening for receiving a full-sized standard ink source. The male threads of the cap engage the second set of female threads of the pen body for closing a writing tip and reducing the length of the pen for storage in the pocket of a user. The male threads of the cap engage the first set of female threads of the body for transforming the pen into an extended-length pen similar in length to a conventional pen and revealing the writing tip for comfortable writing using the pen.

A writing implement comprises a main body and a cap, and the main body comprises a plunger. An undercut is formed on an inner wall of the cap. When the cap is engaging to the main body, a load from the inner wall of the cap is applied to the plunger. The cap is interlocked to the main body when the load against the plunger is reduced or removed. With such a structure, the writing implement can be attached and detached smoothly between two detachable parts such as the cap and the main body. Also, it is possible to reduces friction and wear on an engaging and interlocking section.

A writing instrument, having a writing tip and a writing part, which can receive a writing medium reservoir for the writing instrument, and having a removal aid which is releasably connected to the writing part for assisting the removal of a writing medium reservoir, which can be arranged or is arranged in the writing part, which removal aid having a receiving space for a connectable portion of the writing medium reservoir and one or more connecting parts for releasably connecting the removal aid to the connectable portion of the writing medium reservoir. The or each connecting part is configured such that, by the connecting part bearing against the connectable portion of the writing medium reservoir, the removal aid can be connected or is connected thereto by a releasable frictional connection.

A writing instrument part that improves the releasability of a core pin is provided. In a writing instrument part by the insert molding method in which a wooden barrel material made of natural wood flour and a water-soluble resin binder is injected into a mold, the wooden barrel material and a core pin having a paper straw inserted therein are integrated, and a two-layer structure having a paper straw layer as an inner layer and a wooden barrel layer as an outer layer is formed.

An attachment structure in a writing instrument, includes: a first component; and a second component configured to be fitted into a fitting hole provided at an end of the first component, the second component including: a small-diameter portion; and a large-diameter portion disposed in front of the small-diameter portion; and a first outer step portion disposed between the small-diameter portion and the large-diameter portion, the fitting hole including: a small-diameter hole portion; and an inner step portion disposed in front of the small-diameter hole portion, the small-diameter portion being fitted into or loosely fitted into the small-diameter hole portion, the first outer step portion coming into contact with the inner step portion, the small-diameter hole portion includes a barb portion protruding from the inner face of the small-diameter hole portion, the barb portion being deformable by contact with the small-diameter portion when the second component is fitted.

A writing instrument part that improves the releasability of a core pin is provided. In a writing instrument part by the insert molding method in which a wooden barrel material made of natural wood flour and a water-soluble resin binder is injected into a mold, the wooden barrel material and a core pin having a paper straw inserted therein are integrated, and a two-layer structure having a paper straw layer as an inner layer and a wooden barrel layer as an outer layer is formed.