Mechanical pencil

Patent metadata

Field	Value
Publication number	US-9834032-B2
Application number	US-201414762018-A
Country	US
Kind code	B2
Filing date	Jan 27, 2014
Priority date	Jan 29, 2013
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

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.

First claim

The invention claimed is:

1. A mechanical pencil, comprising:
a rotational drive mechanism including
a rotatable cam,
a first fixed cam, and
a second fixed cam,

wherein the rotatable cam is rotationally driven according to writing pressure applied to a writing lead, such that rotational motion of the rotatable cam is transferred to the writing lead,
wherein the rotatable cam has upper and lower cam faces orthogonal to an axial direction,
wherein the first fixed cam and the second fixed cam face each other with the upper and lower cam faces of the rotatable cam therebetween,
wherein at least one of the first fixed cam and the second fixed cam has a cam face formed on a funnel-shaped inclined surface, and
wherein one of said upper and lower cam faces of the rotatable cam meshing with the cam face on the funnel-shaped inclined surface is formed on a conical inclined surface.

2. The mechanical pencil according to claim 1 , wherein
the rotational drive mechanism supports the rotatable cam so as to be rotatable and axially movable,
the rotatable cam is axially moved backward under the writing pressure applied to the writing lead and is axially moved forward by release of the writing pressure,
the upper cam face and the lower cam face of the rotatable cam are formed by a plurality of circular cam faces, and
the first fixed cam and the second fixed cam are formed by a plurality of circular cam faces.

3. The mechanical pencil according to claim 2 , wherein
the cam faces of the first and second fixed cams are formed on funnel-shaped inclined surfaces, and
the upper cam face and the lower cam face of the rotatable cam are formed on conical inclined surfaces.

4. The mechanical pencil according to claim 1 , wherein
the first fixed cam is formed in a first cylindrical cam formation member,
the second fixed cam is formed in a second cylindrical cam formation member, and
the first cam formation member and the second cam formation member are axially joined together.

5. The mechanical pencil according to claim 1 , wherein
the first fixed cam and the second fixed cam are formed within a base member arranged at a front end portion of a body cylinder constituting an outer part of the mechanical pencil, and
the rotatable cam including the upper and lower cam faces is molded integrally with a slider positioned in the base member.

6. The mechanical pencil according to claim 1 , wherein
the first fixed cam is formed at a stopper attached to a rear end portion of the base member,
the second fixed cam is formed in the base member, and
the rotatable cam including the upper and lower cam faces is accommodated in the base member.

7. A mechanical pencil, comprising:
a rotational drive mechanism including
a rotatable cam, and
a holder member,

wherein the rotatable cam is rotationally driven according to writing pressure applied to a writing lead, such that rotational motion of the rotatable cam is transferred to the writing lead,
wherein the holder member supports the rotatable cam so as to be rotatable and axially movable,
wherein the rotatable cam is axially moved backward under the writing pressure applied to the writing lead and is axially moved forward by release of the writing pressure,
wherein the rotatable cam has upper and lower surfaces orthogonal to the axial direction formed with upper and lower cam faces, the upper and lower cam faces being circular,
wherein a first fixed cam and a second fixed cam are formed at a base portion and a tip portion of an axially long elastic member molded integrally with the holder member, so as to face each other with the upper and lower cam faces of the rotatable cam therebetween,
wherein the second fixed cam at the tip portion of the elastic member is formed on an inclined surface bent at an obtuse angle from the longitudinal tip portion of the elastic member toward an axis of the holder member, and
wherein the lower cam face of the rotatable cam meshing with a cam face of the second fixed cam is formed on a conical inclined surface.

8. The mechanical pencil according to claim 7 , wherein
a cylindrical portion is formed at the base portion of the elastic member in the holder member to support the rotatable cam so as to be rotatable and axially movable,
the first fixed cam with a plurality of circular cam faces is formed at the cylindrical portion,
the cam faces of the first fixed cam are formed on a funnel-shaped inclined surface, and
the cam face of the upper cam in the rotatable cam meshing with the cam faces of the first fixed cam is formed on a conical inclined surface.

9. The mechanical pencil according to claim 7 , wherein the second fixed cam is configured such that two cam faces intersect with each other at one ridge line on an inclined surface bent at an obtuse angle from the longitudinal tip portion of the elastic member toward the axis to shape a sawtooth cam, and a line extended from the ridge line is directed toward the axis.

10. The mechanical pencil according to claim 9 , wherein the second fixed cam is formed to meet the relationship α 1 <α 2 where the angle formed by the inclined surface bent at an obtuse angle from the longitudinal tip portion of the elastic member toward the axis and the line directed toward the longitudinal tip portion of the elastic member is designated as α 1 , and the angle formed by the ridge line of the cam in the second fixed cam and the line directed toward the longitudinal tip portion of the elastic member is designated as α 2 .

11. The mechanical pencil according to claim 7 , wherein
an abutting portion is formed on the outer surface of the elastic member to be in abutment with a part of an inner periphery of the body cylinder constituting an outer part of the mechanical pencil or a part of the inner periphery of a member arranged between the body cylinder and the holder member, and
the abutting portion is configured to reduce the degree of expansion of the elastic member from the axis toward the outside.

12. The mechanical pencil according to claim 11 , wherein
a tapered face is formed at the tip portion of the elastic member, and
a part of the body cylinder or a part of the member arranged between the body cylinder and the holder member comes into axial contact with the tapered face to provide a biasing force to cause the elastic member to expand from the axis toward the outside.

13. The mechanical pencil according to claim 7 , wherein
the holder member includes a cushion member to push axially the rotatable cam supported by the holder member,
a slip member is arranged between the cushion member and the rotatable cam to come into contact with the axial rear end surface of the rotatable cam and slip between the cushion member and the rotatable cam, and
the slip member is attached to the cushion member.

14. The mechanical pencil according to claim 13 , wherein
the cushion member is attached to the holder member by two-color molding, and
the slip member is attached to the cushion member by two-color molding.

15. A mechanical pencil, comprising:
rotational drive mechanism including
a rotatable cam,
a holder member, and

wherein the rotatable cam is rotationally driven according to writing pressure applied to a writing lead, such that rotational motion of the rotatable cam is transferred to the writing lead,
wherein the holder member supports the rotatable cam so as to be rotatable and axially movable,
wherein the rotatable cam is axially moved backward under the writing pressure applied to the writing lead and is axially moved forward by release of the writing pressure,
whe

Assignees

• Mitsubishi Pencil Co

Inventors

• Oomoto Kei

Classifications

• B43K21/00

  Propelling pencils (projecting mechanisms for writing units B43K24/00; multiple-point writing implements B43K27/00) · CPC title

• B43K21/006 Primary

  Pencil-barrels · CPC title

• B43K21/22

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

• B43K23/008

  Holders comprising finger grips (B43K23/004, B43K23/012 take precedence) · CPC title

• B43K29/02

  with rubbers · CPC title