A mechanical pencil has: a shaft tube; a ferrule unit supported by the shaft tube; a lead holding unit having a chuck configured to relatively move with respect to the ferrule unit to eject lead held by the same; and an indication body provided movably in an axial direction. The indication body delimits from rearward a lead storage space formed rearward the chuck in the shaft tube. The indication body located at least at a predetermined position is viewable from outside the shaft tube. A length along the axial direction between a rear end of the lead storage space and a front end of the ferrule unit, in a state where the indication body has moved most rearward along the axial direction, is equal to or more than twice a length of spare lead to be stored in the lead storage space.

A mechanical pencil has: a shaft tube; a ferrule unit supported by the shaft tube; a lead holding unit having a chuck configured to relatively move with respect to the ferrule unit to eject lead held by the same; and an indication body provided movably in an axial direction. The indication body delimits from rearward a lead storage space formed rearward the chuck in the shaft tube. The indication body located at least at a predetermined position is viewable from outside the shaft tube. A length along the axial direction between a rear end of the lead storage space and a front end of the ferrule unit, in a state where the indication body has moved most rearward along the axial direction, is equal to or more than twice a length of spare lead to be stored in the lead storage space.

A mechanical pencil which is configured so that a rotatable cam is rotationally driven with an axis of the rotatable cam relative to a holder member stabled, and smooth operation of a rotational drive mechanism is ensured. The mechanical pencil includes a rotational drive mechanism for driving rotationally a rotatable cam according to writing pressure applied to a writing lead, and transfer rotational motion of the rotatable cam to the writing lead. The rotational drive mechanism includes a holder member supporting the rotatable cam so as to be rotatable, a first fixed cam formed with a funnel-shaped inclined surface Fu and a second fixed cam formed at an obtuse angle α relative to an axial direction. Cam faces of an upper cam and a lower cam alternately meshing with the first and second fixed cams are formed along a conical inclined surface Cs.

A mechanical pencil which is configured so that a rotatable cam is rotationally driven with an axis of the rotatable cam relative to a holder member stabled, and smooth operation of a rotational drive mechanism is ensured. The mechanical pencil includes a rotational drive mechanism for driving rotationally a rotatable cam according to writing pressure applied to a writing lead, and transfer rotational motion of the rotatable cam to the writing lead. The rotational drive mechanism includes a holder member supporting the rotatable cam so as to be rotatable, a first fixed cam formed with a funnel-shaped inclined surface Fu and a second fixed cam formed at an obtuse angle α relative to an axial direction. Cam faces of an upper cam and a lower cam alternately meshing with the first and second fixed cams are formed along a conical inclined surface Cs.

A mechanical pencil 1 includes a rotary member having a ball chuck 11, a rotation drive mechanism 30 having a rotary part 40 and driving the rotary part to rotate in one direction upon receiving a retracting motion in the axial direction due to writing pressure received by the lead clutched by the ball chuck and an advancing motion in the axial direction due to release of the writing pressure, and a cylindrical member 8 made of metal provided at one of the cylindrical barrel and the rotary member, the rotary member configured so as to rotate upon receiving rotational drive force of the rotary part whereby the lead clutched by the ball chuck rotates, the other of the cylindrical barrel and the rotary member slidingly contacting the surface of the cylindrical member whereby rotation of the rotary member due to the rotation drive mechanism is supported.

A mechanical pencil 1 includes a rotary member having a ball chuck 11, a rotation drive mechanism 30 having a rotary part 40 and driving the rotary part to rotate in one direction upon receiving a retracting motion in the axial direction due to writing pressure received by the lead clutched by the ball chuck and an advancing motion in the axial direction due to release of the writing pressure, and a cylindrical member 8 made of metal provided at one of the cylindrical barrel and the rotary member, the rotary member configured so as to rotate upon receiving rotational drive force of the rotary part whereby the lead clutched by the ball chuck rotates, the other of the cylindrical barrel and the rotary member slidingly contacting the surface of the cylindrical member whereby rotation of the rotary member due to the rotation drive mechanism is supported.

A knocking-type writing instrument has a writing refill, such as a pencil lead or an ink cartridge, that is advanced by knocking a knocking member, and an eraser held by an eraser holder disposed at a rear part of the knocking member. When the writing instrument is inclined so that the eraser side faces downward, a control pin provided in the eraser holder and a movable stopper drop by their own weights along a sliding groove of the knocking member. When the control pin drops a predetermined distance and enters a circumferential locking groove provided at a rear end of the sliding groove, detachment of the control pin is prevented by the stopper, and the eraser holder is unable to retract to the inside of the knocking member. In this state, a radial projection on the control pin abuts a rear end face of the knocking holder, whereby the knocking member is locked and can no longer be knocked, and feeding of the writing refill is prevented.

A knocking-type writing instrument has a writing refill, such as a pencil lead or an ink cartridge, that is advanced by knocking a knocking member, and an eraser held by an eraser holder disposed at a rear part of the knocking member. When the writing instrument is inclined so that the eraser side faces downward, a control pin provided in the eraser holder and a movable stopper drop by their own weights along a sliding groove of the knocking member. When the control pin drops a predetermined distance and enters a circumferential locking groove provided at a rear end of the sliding groove, detachment of the control pin is prevented by the stopper, and the eraser holder is unable to retract to the inside of the knocking member. In this state, a radial projection on the control pin abuts a rear end face of the knocking holder, whereby the knocking member is locked and can no longer be knocked, and feeding of the writing refill is prevented.

A mechanical pencil includes a writing lead, a chuck unit for chucking the writing lead, and a cushion spring configured to elastically support the chuck unit in such a manner that the chuck unit is retractable with a writing pressure. An output of the cushion spring, in response to a cushion stroke, is non-linear, and a slope of a spring constant, in a region where the cushion stroke is relatively small, is smaller than a slope of a spring constant in a region where the cushion stroke is relatively large.

A mechanical pencil includes a writing lead, a chuck unit for chucking the writing lead, and a cushion spring configured to elastically support the chuck unit in such a manner that the chuck unit is retractable with a writing pressure. An output of the cushion spring, in response to a cushion stroke, is non-linear, and a slope of a spring constant, in a region where the cushion stroke is relatively small, is smaller than a slope of a spring constant in a region where the cushion stroke is relatively large.