Multifunction writing instrument comprising a body extending in an axial direction and housing at least two retractable writing elements and a ring portion movable in rotation. The ring portion having at least as many pairs of guide surfaces as retractable writing elements. The writing elements include buttons. Each button is configured to cooperate with a respective one of the pair of guide surfaces of the ring portion. Actuation of the button of a writing element facilitates movement of the writing element from the retracted position to the writing position and returns any of the other writing elements in the writing position to the retracted position, whereby at most, one writing element is in the writing position.

A refill for writing implements has an ink reservoir tube (1) made of resin material and formed to be a straight cylinder and a writing tip (2) attached to one end of the ink reservoir tube (1), and a value of an expression of D.sup.4−(D−2t).sup.4 is selected to be 45 or greater, where D denotes an outer diameter of the ink reservoir tube (1) and t denotes a thickness of the ink reservoir tube (1). It is possible to secure the necessary storage amount of ink in the ink reservoir tube (1) without increasing the outer diameter thereof, and is also possible to provide a refill for a writing implement and a writing implement which allow one to keep writing comfortably without feeling of discomfort in writing.

Multifunction writing instrument comprising a body extending in an axial direction and housing at least two retractable writing elements and a ring portion movable in rotation. The ring portion having at least as many pairs of guide surfaces as retractable writing elements. The writing elements include buttons. Each button is configured to cooperate with a respective one of the pair of guide surfaces of the ring portion. Actuation of the button of a writing element facilitates movement of the writing element from the retracted position to the writing position and returns any of the other writing elements in the writing position to the retracted position, whereby at most, one writing element is in the writing position.

Multifunction writing instrument comprising a body extending in an axial direction and housing at least two retractable writing elements and a ring portion movable in rotation. The ring portion having at least as many pairs of guide surfaces as retractable writing elements. The writing elements include buttons. Each button is configured to cooperate with a respective one of the pair of guide surfaces of the ring portion. Actuation of the button of a writing element facilitates movement of the writing element from the retracted position to the writing position and returns any of the other writing elements in the writing position to the retracted position, whereby at most, one writing element is in the writing position.

A composite writing implement according to an embodiment includes a barrel, writing shafts housed in the barrel, a cam main body including a cam projection, an end surface extending along the cam projection, and a latch recess provided in the cam projection, and sliders configured to be connected to respective rear ends of the writing shafts, and include a cam configured to be latchable to the latch recess, and have a sliding contact surface to be pressed against the end surface, wherein the end surface includes a first inclined portion that is positioned on the front end side of the cam projection and is inclined by a first incline angle, and a second inclined portion that is positioned further toward the rear end side of the cam projection than the first inclined portion, and is inclined by a second incline angle that is larger than the first incline angle.

A composite writing implement according to an embodiment includes a barrel, writing shafts housed in the barrel, a cam main body including a cam projection, an end surface extending along the cam projection, and a latch recess provided in the cam projection, and sliders configured to be connected to respective rear ends of the writing shafts, and include a cam configured to be latchable to the latch recess, and have a sliding contact surface to be pressed against the end surface, wherein the end surface includes a first inclined portion that is positioned on the front end side of the cam projection and is inclined by a first incline angle, and a second inclined portion that is positioned further toward the rear end side of the cam projection than the first inclined portion, and is inclined by a second incline angle that is larger than the first incline angle.

A refill for a writing tool includes an ink containing tube that is made from a resin material and formed in a straight cylindrical shape, and a writing tip that is attached to an end of the ink containing tube. A press-fit portion, formed at the end of the ink containing tube, has a thickness being made thickened toward an inner circumferential surface and has an opening hole penetrating in an axial direction at a central portion of the press-fit portion. The writing tip or a relay member supporting the writing tip is press-fitted and attached to the press-fit portion. The refill for a writing tool can ensure a necessary and sufficient amount of ink stored without expanding an outer diameter of the ink containing tube, and sufficiently secure mechanical strength of an end portion, and a writing tool using the same can be provided.

A refill for a writing tool includes an ink containing tube that is made from a resin material and formed in a straight cylindrical shape, and a writing tip that is attached to an end of the ink containing tube. A press-fit portion, formed at the end of the ink containing tube, has a thickness being made thickened toward an inner circumferential surface and has an opening hole penetrating in an axial direction at a central portion of the press-fit portion. The writing tip or a relay member supporting the writing tip is press-fitted and attached to the press-fit portion. The refill for a writing tool can ensure a necessary and sufficient amount of ink stored without expanding an outer diameter of the ink containing tube, and sufficiently secure mechanical strength of an end portion, and a writing tool using the same can be provided.

Multifunction writing instrument comprising a body extending in an axial direction and housing at least two retractable writing elements and a ring portion movable in rotation. The ring portion having at least as many pairs of guide surfaces as retractable writing elements. The writing elements include buttons. Each button is configured to cooperate with a respective one of the pair of guide surfaces of the ring portion. Actuation of the button of a writing element facilitates movement of the writing element from the retracted position to the writing position and returns any of the other writing elements in the writing position to the retracted position, whereby at most, one writing element is in the writing position.

Multifunction writing instrument comprising a body extending in an axial direction and housing at least two retractable writing elements and a ring portion movable in rotation. The ring portion having at least as many pairs of guide surfaces as retractable writing elements. The writing elements include buttons. Each button is configured to cooperate with a respective one of the pair of guide surfaces of the ring portion. Actuation of the button of a writing element facilitates movement of the writing element from the retracted position to the writing position and returns any of the other writing elements in the writing position to the retracted position, whereby at most, one writing element is in the writing position.