Abstract: A mechanical pencil has a main body housing a lead-feeding mechanism which includes a chuck and a clamping ring. A tapered member is provided at a front end of the main body, and a slider is mounted to undergo back and forth movement within the tapered member. A lead protection pipe protrudes from a front end of the tapered member when the slider moves forward, and an outer pipe is provided at a front end of the tapered member and surrounds a front end of the lead protection pipe. The slider moves backward as the writing proceeds so the lead protection pipe is not bent by a writing pressure, whereby a lead can be fed by a few knocking operations. The outer pipe is fixed to the tapered member or provided on an outer pipe holder inserted into the tapered member. The outer pipe holder is fixed to the inside of the tapered member or disposed to move back and forth in the tapered member.

Abstract: A mechanical pencil has a main body housing a lead-feeding mechanism which includes a chuck and a clamping ring. A tapered member is provided at a front end of the main body, and a slider is mounted to undergo back and forth movement within the tapered member. A lead protection pipe protrudes from a front end of the tapered member when the slider moves forward, and an outer pipe is provided at a front end of the tapered member and surrounds a front end of the lead protection pipe. The slider moves backward as the writing proceeds so the lead protection pipe is not bent by a writing pressure, whereby a lead can be fed by a few knocking operations. The outer pipe is fixed to the tapered member or provided on an outer pipe holder inserted into the tapered member. The outer pipe holder is fixed to the inside of the tapered member or disposed to move back and forth in the tapered member.

Abstract: A rotary feeding mechanism for axially feeding a rod-shaped body from a main body by rotating a tapered tip has a simple structure and can be produced economically. The main body is provided with plural open windows are arranged at a predetermined thread pitch along an axial direction of the main body. The tapered tip is installed rotatably on the main body, and a guide pipe extending toward the inside of the main body is fixed to the tapered tip. A holder for holding the rod-shaped body is housed in the main body, and the holder and the guide pipe are connected non-rotatably and movably in the axial direction. The outer periphery of the holder has an external thread which engages with the windows so that when the tapered tip is rotated, the holder moves in the axial direction while rotating via the guide pipe, and the rod-shaped body can be projected from or retracted into the main body.

Abstract: A rotary feeding mechanism for axially feeding a rod-shaped body from a main body by rotating a tapered tip has a simple structure and can be produced economically. The main body is provided with plural open windows are arranged at a predetermined thread pitch along an axial direction of the main body. The tapered tip is installed rotatably on the main body, and a guide pipe extending toward the inside of the main body is fixed to the tapered tip. A holder for holding the rod-shaped body is housed in the main body, and the holder and the guide pipe are connected non-rotatably and movably in the axial direction. The outer periphery of the holder has an external thread which engages with the windows so that when the tapered tip is rotated, the holder moves in the axial direction while rotating via the guide pipe, and the rod-shaped body can be projected from or retracted into the main body.

Abstract: A mechanical pencil has a hollow longitudinal main body and a slider slidably mounted in a front end of the main body. The slider has a through-hole through which a lead is fed and a front end face formed into a spherical surface centering around the through-hole for contacting a writing surface during a writing operation of the mechanical pencil.

Abstract: A writing instrument has a writing refill slidably disposed in a tubular casing. A rotary cam mechanism extends and retracts the writing refill in response to knocking of a knocking member at a rear end of the casing. The rotary cam mechanism includes a cam cylinder inserted axially into the rear end of the casing, and projections on the cam cylinder engage with apertures in the casing to prevent axial movement of the cam cylinder inside the casing. Rotational movement of the knocking member rotates the cam cylinder and disengages the projections from the apertures, thereby permitting withdrawal of the cam cylinder from the casing and replenishment of the writing refill.

Abstract: A hand-held instrument has a variable contour grip, a main body having a grip-attaching portion, and a tubular grip body made of a resilient material and mounted around the grip-attaching portion of the main body for undergoing rotation relative thereto. Each of an outer circumferential surface of the grip-attaching portion and an inner circumferential surface of the grip body has a non-circular cross-sectional shape so that when the grip-attaching portion and the grip body are rotated relative to one another, the grip body undergoes deformation so that portions thereof or contracted and other portions thereof are expanded to thereby change an outer configuration or contour of the grip body.

Abstract: An automatic mechanical pencil has a tubular piece removably connected to a barrel cylinder, and a slider for frictionally holding a lead and being movably disposed in a front portion of the tubular piece. A lead chuck is disposed in the barrel cylinder for releasably holding the lead so as to allow forward movement of the lead but prevent backward movement thereof. A first spring urges the slider forward and the lead chuck backward so that when a writing front end of the writing instrument is released from a writing surface, the lead is automatically fed by urging the slider forward. A lead reservoir is disposed rearwardly of the lead chuck to supply the lead to the lead chuck. The lead reservoir has a reservoir main body, a pipe holder connected to a front end of the reservoir main body and having a guide projection, and a stopper disposed around an outer periphery of the pipe holder and having a receiving groove engageable with the guide projection.

Abstract: A writing instrument is capable of functioning both as an automatic mechanical pencil and as a shaking-type mechanical pencil. The writing instrument has a barrel cylinder constituted by a front cylinder detachably connected to a rear cylinder. A slider is disposed at the front end of the barrel cylinder, and a lead chuck, such as a ball chuck, is disposed rearwardly of the slider. A slider spring urges the slider forward and urges the lead chuck rearward. A lead reservoir is movably disposed rearwardly of the lead chuck. Around the outer periphery of the lead reservoir, a weight is disposed to undergo back-and-forth movement in an axial direction. On the outer periphery of the lead reservoir is disposed a weight-receiving cylinder against which the rear end of the weight abuts when the writing instrument is shaken. A knocking spring urges the weight-receiving cylinder forward and urges the lead reservoir rearward.

Abstract: An automatic mechanical pencil has a tubular piece removably connected to a barrel cylinder, and a slider for frictionally holding a lead and being movably disposed in a front portion of the tubular piece. A lead chuck is disposed in the barrel cylinder for releasably holding the lead so as to allow forward movement of the lead but prevent backward movement thereof. A first spring urges the slider forward and the lead chuck backward so that when a writing front end of the writing instrument is released from a writing surface, the lead is automatically fed by urging the slider forward. A lead reservoir is disposed rearwardly of the lead chuck to supply the lead to the lead chuck. The lead reservoir has a reservoir main body, a pipe holder connected to a front end of the reservoir main body and having a guide projection, and a stopper disposed around an outer periphery of the pipe holder and having a receiving groove engageable with the guide projection.

Abstract: A writing instrument is capable of functioning both as an automatic mechanical pencil and as a shaking-type mechanical pencil. The writing instrument has a barrel cylinder constituted by a front cylinder detachably connected to a rear cylinder. A slider is disposed at the front end of the barrel cylinder, and a lead chuck, such as a ball chuck, is disposed rearwardly of the slider. A slider spring urges the slider forward and urges the lead chuck rearward. A lead reservoir is movably disposed rearwardly of the lead chuck. Around the outer periphery of the lead reservoir, a weight is disposed to undergo back-and-forth movement in an axial direction. On the outer periphery of the lead reservoir is disposed a weight-receiving cylinder against which the rear end of the weight abuts when the writing instrument is shaken. A knocking spring urges the weight-receiving cylinder forward and urges the lead reservoir rearward.

Abstract: A hand-held instrument has a variable contour grip, a main body having a grip-attaching portion, and a tubular grip body made of a resilient material and mounted around the grip-attaching portion of the main body for undergoing rotation relative thereto. Each of an outer circumferential surface of the grip-attaching portion and an inner circumferential surface of the grip body has a non-circular cross-sectional shape so that when the grip-attaching portion and the grip body are rotated relative to one another, the grip body undergoes deformation so that portions thereof or contracted and other portions thereof are expanded to thereby change an outer configuration or contour of the grip body.

Abstract: A writing instrument has a tubular casing having a longitudinal axis, a through-hole extending in a longitudinal direction of the longitudinal axis, a wall surface, and an aperture formed in the wall surface. A writing refill is inserted in the through-hole of the tubular casing for extension out of the casing to a writing position and retraction into the casing to a retracted position. A rotary cam mechanism is accommodated in the through-hole of the casing for extending and retracting the writing refill between the writing position and the retracted position. The rotary cam mechanism comprises a cam cylinder having a projection engaging the aperture of the casing and a stationary cam, a rotary cam engageable with the stationary cam of the cam cylinder, and a knocking cam engageable with the stationary cam of the cam cylinder and the rotary cam.

Abstract: A writing instrument has a tubular member having a longitudinal axis and an aperture at an end thereof. A writing component is mounted in the tubular member and has a writing tip at an end portion thereof. The tubular member and the writing component are movable relative to one another in an axial direction along the longitudinal axis of the tubular member between a writing position at which the writing tip protrudes from the aperture of the tubular member and a housed position at which the writing tip is disposed in the tubular member. An airtight sleeve is connected to the end portion of the writing component for movement between an advanced position and a retracted position. The airtight sleeve has a bore through which the end portion of the writing component passes during movement of the writing component between the writing position and the housed position.

Abstract: A writing instrument has a tubular member having a longitudinal axis and an aperture at an end thereof. A writing component is mounted in the tubular member and has a writing tip at an end portion thereof. The tubular member and the writing component are movable relative to one another in axial directions along the longitudinal axis of the tubular member between a writing position at which the writing tip protrudes from the aperture of the tubular member and a housed position at which the writing tip is disposed in the tubular member. An airtight sleeve is connected to the end portion of the writing component for movement between an advanced position and a retracted position. The airtight sleeve has a bore through which the end portion of the writing component passes during movement of the writing component between the writing position and the housed position.

Abstract: A mechanical pencil comprises a main body, a lead-feeding mechanism disposed in the main body for gripping a lead at a lead-gripping position and for feeding the lead to an advanced position, and a mouthpiece connected to the main body. A slider is slidably fitted in the mouthpiece. A lead-holding member is disposed in the slider for frictionally holding the lead fed to the advanced position. A slider-resisting member is disposed in contact with the slider for applying a frictional resistance to the slider larger than a frictional resistance of the lead-holding member.