A pressure fluctuation buffering mechanism includes a buffer space connected to a brush via a paint flow space (a paint tank and a paint feeder) through which paint flows. The pressure fluctuation buffering mechanism buffers pressure fluctuations in the paint tank by the flow of paint and air between the paint flow space and the buffer space. The pressure fluctuation buffering mechanism includes a first buffer space forming member for forming a first buffer space in the buffer space, and a second buffer space forming member for forming a second buffer space in the buffer space. The paint between the first buffer space and the paint flow space flows more easily than the paint between the second buffer space and the paint flow space.

A writing implement in which a joint connecting an ink supply section and a ballpoint pen tip together is configured from three members. The three members configuring the joint are a substantially cylindrical center member, a substantially cylindrical surrounding member formed at the outer periphery of the center member, and an interposing member that is molded by a soft member molded so as to cover the outer periphery of the center member and the surrounding member. An annular gap section is provided between the center member and the surrounding member. The leading end of the ink supply section is fitted into the gap section. The joint is formed by two color molding. The center member and the surrounding member are molded by primary molding, and the interposing member is integrally molded onto the center member and the surrounding member by secondary molding.

A writing instrument includes: a writing instrument body and an ink cartridge. The ink cartridge includes a bottomed cylindrical container with an opened front end and a plug fitted into an inner circumferential surface of an opening of the container. The writing instrument body includes a projection that opens the ink cartridge when inserted into the opening to press the plug rearward and an air tight connecting portion, formed separately from the projection, that surrounds the projection. The opening is divided into a plurality of openings by air tight fitting the opening in the air tight connecting portion. A plurality of longitudinal channels are formed on an outer periphery of the projection. At least one of the plurality of channels serves as an ink channel and at least one of the other channels serves as an air intake path.

A writing instrument includes: a writing instrument body and an ink cartridge. The ink cartridge includes a bottomed cylindrical container with an opened front end and a plug fitted into an inner circumferential surface of an opening of the container. The writing instrument body includes a projection that opens the ink cartridge when inserted into the opening to press the plug rearward and an air tight connecting portion, formed separately from the projection, that surrounds the projection. The opening is divided into a plurality of openings by air tight fitting the opening in the air tight connecting portion. A plurality of longitudinal channels are formed on an outer periphery of the projection. At least one of the plurality of channels serves as an ink channel and at least one of the other channels serves as an air intake path.

Provided is a ballpoint pen refill including: an ink storage tube made of a synthetic resin and storing an ink thereinside; a ball holder made of a synthetic resin and attached to a distal end of the ink storage tube; a ball pressing rod mounted inside the ball holder; and a writing ball stored in a distal end of the ball holder and having a rear end side held by the ball pressing rod, in which the ball pressing rod includes: a fixing portion fixed to the ball holder; a movable portion slidable in a front-rear direction with respect to the ball holder; a compression portion connecting the fixing portion and the movable portion; and a rearward movement restricting portion protruding from a distal end of the fixing portion and provided with a gap from a rear end of the compression portion.

Please replace the current abstract with the following amended abstract.

An ink retention member includes an ink retention portion including ink retention grooves and ink guiding grooves. The ink retention member includes a first horizontal hole penetrating radially therethrough and being in communication with an inner hole. The first horizontal hole and the ink guiding grooves are formed not to communicate with each other in a transverse cross-section. The first horizontal hole is provided in a rear half portion of the ink retention portion. The ink retention member includes a second horizontal hole that is disposed forward from the first horizontal hole, radially penetrates therethrough, and communicates with the inner hole. The first horizontal hole and the second horizontal hole are each provided to penetrate at least one comb tooth axially and communicate with the ink retention grooves adjacent to the comb tooth.

Please replace the current abstract with the following amended abstract.

An ink retention member includes an ink retention portion including ink retention grooves and ink guiding grooves. The ink retention member includes a first horizontal hole penetrating radially therethrough and being in communication with an inner hole. The first horizontal hole and the ink guiding grooves are formed not to communicate with each other in a transverse cross-section. The first horizontal hole is provided in a rear half portion of the ink retention portion. The ink retention member includes a second horizontal hole that is disposed forward from the first horizontal hole, radially penetrates therethrough, and communicates with the inner hole. The first horizontal hole and the second horizontal hole are each provided to penetrate at least one comb tooth axially and communicate with the ink retention grooves adjacent to the comb tooth.

To make it possible to easily change a writing line width.

A ballpoint pen chip that brings a front half part side of a transfer ball into contact with an inward annular protrusion on a front end side in a chip body from a backward side of the inward annular protrusion and receives a rear half part side of the transfer ball with a front end part of a receiving member. The receiving member includes, on a front end side thereof, a reduction part gradually reduced in a cross-sectional area forward. A front-most end part of the reduction part is disposed backward from the transfer ball. A portion of the receiving member further on a rear side than the reduction part is unretreatably fixed to the chip body and configured to elastically contract when a pressing force is received from the transfer ball.

To make it possible to easily change a writing line width.

A ballpoint pen chip that brings a front half part side of a transfer ball into contact with an inward annular protrusion on a front end side in a chip body from a backward side of the inward annular protrusion and receives a rear half part side of the transfer ball with a front end part of a receiving member. The receiving member includes, on a front end side thereof, a reduction part gradually reduced in a cross-sectional area forward. A front-most end part of the reduction part is disposed backward from the transfer ball. A portion of the receiving member further on a rear side than the reduction part is unretreatably fixed to the chip body and configured to elastically contract when a pressing force is received from the transfer ball.

Disclosed are a knock type direct liquid pen refill assembly and a writing pen. The pen refill assembly comprises an ink cylinder assembly (100), a pen tip (200) and an elastic member (300). An ink guide core (150) is provided in the ink cylinder assembly. The pen tip (200) is arranged at one end of the ink cylinder assembly (100). An ink duct (210) is formed inside and passes through the pen tip (200). A ball member (230) is provided at an ink outlet end of the ink duct (210). The ink guide core (150) partially passes through the ink duct (210), and one end of the ink guide core (150) is abutted against the ball member (230). The elastic member (300) is sleeved at the periphery of the ink guide core (150) and positioned inside the ink duct (210). The elastic member is abutted against the ball member to exert a force, such that the ball member is closely attached to an inner wall of the ink outlet end, the ball member forms sealed contact with the inner wall of the ink outlet, and ink volatilization and leakage are avoided.