Mechanical pencil

Patent metadata

Field	Value
Publication number	US-12214616-B2
Application number	US-202218578444-A
Country	US
Kind code	B2
Filing date	Jul 11, 2022
Priority date	Jul 20, 2021
Publication date	Feb 4, 2025
Grant date	Feb 4, 2025

Abstract

A mechanical pencil includes a ball chuck, a rotation drive mechanism having a rotary part, a feedout cam face having a step part in the axial direction, an input member rotating upon receiving a rotational drive force of the rotary part, and an output member having an abutting part abutting against the feedout face and a slider provided with a holding chuck holding lead, the abutting part moves along the feedout face corresponding to rotation of the output member and so that advancing motion of the slider when the abutting part drops into the drop difference causes lead held by the holding chuck to be pulled out by the ball chuck, and further including a clutch mechanism transmitting rotational movement of the input member to the output member.

First claim

The invention claimed is:

1. A mechanical pencil comprising
a ball chuck allowing advance of lead and preventing retraction,
a rotation drive mechanism having a rotary part and receiving a retracting motion in the axial direction due to writing pressure received by the lead gripped by the ball chuck and an advancing motion in the axial direction due to release of writing pressure so as to make the rotary part be driven to rotate in one direction,
a feedout face having a ring-shaped cam face and a drop difference in the axial direction provided at the ring-shaped cam face,
an input member rotating upon receiving a rotational drive force of the rotary part, and
an output member having an abutting part abutting against the feedout face and a slider provided with a holding chuck holding lead,
configured so that the abutting part moves along the feedout face corresponding to rotation of the output member and so that advancing motion of the slider when the abutting part drops into the drop difference causes lead held by the holding chuck to be pulled out by the ball chuck, and
further comprising a clutch mechanism transmitting rotational movement of the input member to the output member so that when the input member rotates by exactly a first rotational angle, the output member rotates by exactly a second rotational angle smaller than the first rotational angle.

2. The mechanical pencil according to claim 1 , wherein the clutch mechanism is a claw clutch or friction clutch.

3. The mechanical pencil according to claim 1 , wherein the clutch mechanism is a claw clutch, the input member is formed with an input cam face and the output member is formed with an output cam face facing the input cam face, the input cam face and output cam face engage at only part of rotational movement of the rotary part, and rotational movement of the rotary part is transmitted through the input member to the output member.

4. The mechanical pencil according to claim 3 , wherein
the rotation drive mechanism has a first cam-forming member and second cam-forming member,
the rotary part is formed in a circular ring shape, one end face and the other end face in the axial direction are respectively formed with a first cam face and a second cam face, and the first cam face and the second cam face have a first fixed cam face and a second fixed cam face formed at the first cam-forming member and the second cam-forming member respectively facing them arranged at them,
the mechanical pencil configured so that retracting motion of the ball chuck due to the writing pressure causes the first cam face of the rotary part to abut against and mesh with the first fixed cam face and so that release of the writing pressure causes the second cam face of the rotary part to abut against and mesh with the second fixed cam face,
in the state where the first cam face of the rotary part has meshed with the first fixed cam face, the second cam face and the second fixed cam face of the rotary part are set to a relationship shifted in phase with respect to one tooth of the cam in the axial direction and, in the state where the second cam face of the rotary part has meshed with the second fixed cam face, the first cam face of the rotary part and the first fixed cam face are set to a relationship shifted in phase with respect to one tooth of the cam in the axial direction, and
a pitch of cam in the clutch mechanism is set smaller than a pitch of cam in the rotation drive mechanism.

5. The mechanical pencil according to claim 1 , configured so that the lead rotates by the ball chuck rotating by receiving rotational drive force of the rotary part.

6. The mechanical pencil according to claim 1 , wherein between the output member and the cylindrical barrel, a viscous fluid inhibiting movement of the output member in the axial direction is arranged.

7. The mechanical pencil according to claim 1 , configured so that the height of the drop difference is adjusted so that that amount of feedout of lead is adjusted.

8. The mechanical pencil according to claim 7 , further comprising a ring shaped or cylindrical shaped first cam member and a ring shaped or cylindrical shaped second cam member arranged outside the first can member in the diametrical direction, the feedout face configured by the first can member and the second cam member cooperating.

9. The mechanical pencil according to claim 8 , whereby a height of the drop difference is adjusted by making the first can member and the second cam merber rotate relatively about a center axis.

Assignees

• Mitsubishi Pencil Co

Inventors

• Fukuda Takamasa
• Koizumi Yusuke

Classifications

• B43K21/22 Primary

  Writing-cores gripping means, e.g. chucks · CPC title

• B43K21/033 Primary

  with automatic feed by pressure during use of pencil · CPC title

• B43K21/16 Primary

  with stepwise feed of writing-cores · CPC title