US3389955A

US3389955A - Push-out type mechanical pencil

Info

Publication number: US3389955A
Application number: US532972A
Authority: US
Inventors: Matsumoto Hiroyuki
Original assignee: Dai Nihon Bungu Co Ltd
Current assignee: Dai Nihon Bungu Co Ltd
Priority date: 1965-05-12
Filing date: 1966-03-09
Publication date: 1968-06-25
Anticipated expiration: 1985-06-25

Description

June 25, 1968 HlRoYuKl MATSUMOTO 3,389,955

PUSH-OUT TYPE MECHANICAL PENCIL Filed March 9, 1966 2 Sheets- Sheet l INVENTOR hem/W0 /WJ R50/v70 To BY www *PIM ATTORNEYS June 25, 1968 HmoYuKl MATsUMo-ro 3,389,955

PUSHOUT TYPE MECHANICAL PENCIL y Filed March 9, 1966 2 Sheets-Sheet 2 FIG. 6

FIG. 7

INVENToR H VUK NABU/V072? BY WA ZM/WMWATTORNEYS United States Patent O "ice 3,389,955 PUSH-OUT TYPE MECHANICAL PENCIL Hiroyuki Matsumoto, Tokyo, Japan, assigner to Dainihon Bungu, Kabu Shikigaisha, also known as The Japan Stationery Co., Ltd., Tokyo, Japan, a corporation of Japan Filed Mar. 9, 1966, Ser. No. 532,972 Claims priority, application Japan, May 12, 1965, 40/ 36,766 4 Claims. (Cl. 401-94) ABSTRACT OF THE DISCLOSURE In conventional ever-sharp pencils of the push-out type, the center bore of a front metal member has a diameter which is larger than the outer diameter of a lead, and an arcuate leaf spring is mounted on the inner surface thereof so that the lead, when pushed out, may not be retracted. A principal disadvantage of this arrangement lies in the fact that it is difficult to bring the lead, which is urged by said spring, into alignment with the center bore of a front metal member in the axial direction, the lead being liable to be deflected and broken. When the lead is broken in a space in front of a chuck, a broken piece of lead in the center bore is slightly deviated from the center at its trailing end as it is subjected to the force of the leaf spring, so that the leading end of the lead, when pushed by the chuck, is brought out of alignment with the trailing end of said broken piece of lead. If this occurs, the lead will become stuck in the center bore, thereby putting the pencil out of service.

Another disadvantage is that a cap is liable to slip olf its position and get lost while in use, since the cap which is pressed by a nger to push out the lead is merely mounted on a lead cylinder projecting out of the upper end of a main body.

It is an object of this invention to provide an ever-sharp pencil of the push-out type which has a lead retraction prevention member in the form a cylinder having a plurality of longitudinal slits, said lead retraction prevention member being firmly mounted in a space between the center bore of a front metal member and the front end of a chuck. The center bore of said lead retraction prevention member and the center bore of said front metal member have a diameter which is substantially identical with the outer diameter of the lead so that the lead cannot be deected in the bores even if it is broken. A broken piece of lead is not deflected but positively pushed out by the other broken piece of lead pushed by the chuck, thereby preventing the lead from becoming stuck in the pencil.

It is another object of this invention to provide an eversharp pencil of the push-out type which has on the upper end of a main body a cap for pushing out the lead which never slips olf its position while in use.

One embodiment of the invention will now be explained with reference to the drawings wherein:

FIG. l is a sectional elevation of one embodiment of this invention with the main body and the front metal member being out away to show the interior;

3,389,955 Patented `lune 25, 1968 FIG. 2 is an exploded elevation of said front metal member;

FIG. 3 is an enlarged sectional elevation along the line A-A of FIG. l;

FIG. 4 is a view similar to FIG. 3 and showing an ever-sharp pencil of the conventional type;

FIG. 5 is an exploded sectional elevation of the pushdown portion of the embodiment shown in FIG. 1;

FIG. 6 is an enlarged fragmentary sectional elevation of another embodiment of the push-down portion, shown with a cap mounted thereon; and

FIG. 7 is an enlarged fragmentary sectional front elevation of the embodiment illustrated in FIG. 6, shown with a cap being removed.

The ever-sharp pencil illustrated in the drawings comprises a main body 1 having a lead cylinder 2 inserted therein. Threadably and integrally mounted on the lower end of the lead cylinder 2 is a chuck 4 for gripping and holding a lead, said chuck 4 being urged upwardly by a spring 5. A spring rest 6 is threadably mounted in the lower end of the main body, and an annular ring 8 which abuts against an offset portion formed on the front inner surface of said spring rest 6 bears against the chuck 4 which is urged upwardly by the spring 5, so that a lead is gripped and held by the chuck 4.

An ever-sharp pencil of the push-out type described hereinabove is known in the prior art. According to this invention, the portion of the spring rest 6 which projects out of the main body is externally threaded at 9 and is threadably received in an internally threaded rear opening 11 of a lead retraction prevention member 10. The aforementioned annular ring 8 is operatively brought into contact with the oor surface 12 thereof. There is formed in the center of said oor surface a recess 13 which is adapted to receive therein the chuck 4, said recess 13 having a center bore 15 adapted to receive the lead 14 therein. A cylindrical body 16 is made resilient by virtue of a plurality of longitudinal slits 17 formed therein. The front end of said cylindrical body 16 yieldingly bears against the lead 14 by proper force of resilience.

A front metal member 19 has an opening whose internally threaded rear portion 20 threadably receives therein externally threaded center portion 18 of the lead retraction prevention member 10. The intermediate portion 21 of said opening snugly receives therein the cylindrical body 16 of lead retraction member 10. The center bore 22 formed in the front end of said front metal member 19 is in alignment with the center bore 15 of the cylindrical body 16 in the axial directions.

Referring to FIG. 5, the inner surface of the upper end of the main body 1 is threaded at 23 and threadably receives therein the lower end of a cylindrical holder 24 having an externally threaded portion 25. A cap 26 for the lead cylinder 2 has a front offset portion 27 which abuts against the upper end of the lead cylinder 2, and is provided with a rear offset portion 29 which abuts against an internal offset portion 30 of the cylindrical holder 24. It will be appreciated from the foregoing description that the cap 26 never slips olf its position unless the cylindrical holder 24 is removed, so that the cap will never become lost.

In operation, pressing down the cap 26 brings the annular ring S into contact with the floor surface 12, and

only the chuck 4 enters the recess 13 together with the lead 14. The chuck 4, when released from its engagement with the annular ring 8, spreads apart, so that the lead stops in its forward movement. Releasing a linger from the cap 26 enables the chuck 4 to be restored to its upper position by the biasing force of the spring 5, but the lead is prevented from moving backwardly by the lead retraction prevention member 10. When the chuck 4 is restored to its original position, it is pressed on its outer circumferential surface by they annular ring 8 and rmly grips and holds the lead 14. Thus, the present invention makes it possible to bring the chuck 4, the lead retraction prevention member 10 and the front metal member 19 into alignment with one another in the axial direction, so that the lead pushed out the chuck 4 is introduced into the center bore 1S of the lead retraction prevention member 10 without being deflected, and thence into the center bore 22 of the front metal member 19. The lead 14 is held so intimately in the bore that the impact of the pencil dropping from a height of several feet onto the ground will not cause the lead to be broken within the pencil. Even if the lead 14 is broken within the pencil by a great impact, broken pieces of lead will be pushed out by the lead pushed by the chuck 4, thereby preventing the broken pieces of lead from becoming stuck within the pencil.

The arrangement shown in FIGS. 6 and 7 may be used to prevent the cap from being dislodged from its position on the upper end of the lead cylinder. The upper end of the main body 1 is internally threaded at 31, and a projection 32 formed on the outerv circumferential surface of the front end of a cap 3 is adapted to threadably engage said threaded portion 31. In inserting a lead, the cap 3' is rotate to the left to release the projection 32 from its engagement with the threaded portion 31 of the main body 1 so that the cap 3 may be removed. When the cap 3 is in the condition shown in FIG. 7, it is impossible for the cap 3 to push the lead cylinder in the main body even if the cap is pushed down by a iinger, for the projection 32 abuts against the outer end of the threaded portion 31. Turning the cap 3 to the right to bring the projection 32 into a position inwardly of the threaded portion 31 of the main body 1 as shown in FIG. 6 enables the cap 3 to freely move upwardly and downwardly. Moreover, the cap 3 never slips oit its position because the projection 32 abuts against the inner end of the threaded portion 31 of the main body 1.

While a preferred embodiment of the invention has been described and illustrated, it is to be understood that the invention is not limited to its precise form, and that changes may be made therein without departing from the scope of the invention which is deiined in the appended claims.

What is claimed as novel is:

1. In an ever-sharp pencil of the push-out type having a cylindrical main body open at both Vends, `a lead carrying cylinder centrally and slidably positioned within'v said main body, a chuck for gripping the lead carried in the lead carrying cylinder, said chuck being secured to the forward end `of the lead carrying cylinder, chuck closing means mounted on the main body contiguous to said chuck whereby relative movement between the chuck and chuck closing means causes the chuck to grip the lead, and wherein the improvement resides in the means on the other end of the main body by which the lead ca'rrying cylinder is operated and retained Within the main body; said means comprising an operating member slidably carried in the other end of the main body, said operating member engaging the corresponding end portion of the lead carrying cylinder to longitudinally move it through the main body when the operating member is moved and stop means for retaining the operating member in the other end of the main body.

2. The invention as described in claim 1 and wherein the operating member comprises a plunger and there is provided a cylindrical cap mounted on the respective end of the main body, said cylindrical cap having a boreY aligned with the longitudinal bore of the main body, said plunger being slidably positioned in the cap bore.

3. The invention as described in claim 2 and wherein the cylindrical cap is threadedly secured to the main body and further wherein the stop means comprises an abutmenton the plunger adapted to cooperate with an abutment on the inner portion of the cylindrical cap to retain the plunger within the cylindrical cap.

`4. The invention as described in claim 1 and wherein the operating member comprises a cylindrical operator engaging the respective end of the lead carrying cylinder and extending beyond the open end of the main body and the stop means comprises cooperating stop members on the main body and the cylindrical operator.

References Cited UNITED STATES PATENTS 1,373,278 3/1921 Vierling et al 401-67 X 1,886,371 ll/1932 Boman lOl-67 2,484,640 10/ 1949 Mustard 401-67 LAWRENCE CHARLES, Primary Examiner.