US2503080A - Mechanical pencil with push-button type lead feeding means - Google Patents

Description

I. D. TEFFT El' AL MECHANICAL PENCIL WITH PUSH BUTTON y April 4, 195o TYPE LEAD FEEDING MEANS 2 Sheets-Sheet l Filed March 4, 1946 t er:

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April 4, 1950 l. D. TFFT ETAI. MECHANICAL PENCTL WITH PusH BUTTON TYPE LEAD FEEDING MEANS Filed March 4, 1946 2 Sheets-Sheet 2 INVENTORS. fUcznffZ, BY UQTLZ 55ML Patented Apr. 4, 1950 Ivan D. Tefft and Marlin S. Baker, Janesville,

Wis., assignors to The Parker 'Pen"Company, Janesville, Wis., a corporation of Wisconsinv Application March 4, 1946, serial No. 651,785y i l This invention "relates to mechanical pencils, and has. to do particularlywith a mechanical pencil wherein the writing lead is fed step-bystep in response to repeated operations of a pushbutton or like' means. Y

One of the objects of our invention is to providean .improved step-by-step continuous feed mechanical pencil whichis of simplified construction, will perform reliably, and is capable of being manufactured economically.'

Another object is to providea pushbutton operated mechanical pencil which will feed out, consecutively, one stick of lead after another, in step-by-step fashion as required, with a minimum of lead breakage, and which embodies a smaller number of partsr and is easier to assemble than prior step-by-step pencils.

` A further object is to provide a mechanical pencil of the push-button operated step-by-step feed type wherein the various parts do not necessitate such extremely close manufacturing tolerances as would be diflicult to maintain, andv wherein none of the parts involve the need for inordinately expensive special tools-thus making it possible to produce a thoroughly dependable product without incurring a large capitalk layout. f

Still another object is to provide astep-bystep feed mechanism which is not susceptible of becoming clogged, and thus rendered inoperative,

bygraphite. dust resulting from abrasionof the writing leads'.

An importantv feature of our invention resides f in the simplicity of construction and economy of' manufacture which is achieved by so arrangi ing' the lead guide tube. that it lightly grips the lead so that the lead is drawn forward with the tube but can readily move lengthwise relatively t0 the tubewhen restrained by the clutch. vvBy so doing the number of lrequired parts is minimizged without in any way impairing the. per formance ofthe pencil.

Other objects and advantages of our invention will be apparent from the ensuing detailedfdescription. f y

Inthe drawings: Figure 1 is an elevational view of a mechani# cal pencil according to a preferredembodiment of our invention;

Fig. 2 is a longitudinal sectional View, on an enlargeclscale, of the front end of `the pencil ofl Fig. 1,. showing the lead-propelling mechanism in normal condition; y

Fig. 3 is a sectional'view: identical with Fig. 2 except that the moving parts of the lead-propelling mechanisms are shown in an intermediate position which they assume during each retractive movement of the' pushbutton and prior to completion thereof; i D

Fig. 4 is a transverse sectional view taken along line 4 4 ofFig. 2; f Y

Fig. 5 is a longitudinal sectional view takenv along line 5--5 of Fig. 2'; f

Fig. 6 is a sub-assembly, in elevation, comprising a leadguide tube on which is mounted a clutch; v

Fig. 7 is a transverse sectional view taken alongv line 1--1 of Fig. 2, showing the clutch jaws engaging the lead;

Fig. 8 is a 'transverse section identical with Fig. 7 but showing the clutch jaws vreleased and out of' engagement with' the `Writing lead;

Fig 9 is a' transverse sectional view taken` along line 9-9 of Figf2'; and

Fig. 10 is a large scale longitudinal sectional view of the rear end of the pencil, showing details of the pushbutton and adjacent parts.

Thel pencil illustratedis largely conventional in outward appearance and comprises an elon- 5 gate hollow barrel I,` having a conically tapered tip 2, and from vthe rear end of which projects a pushbutton 3. The function of said pushlbutton is to cause fthe writing lead 4 to be fed out stepby-stepthe lead being advanced a small amountr in response to each depression of the pushbutton. lThe pencil may be equipped with a spring-type pocket clip 5 of conventional design.

Tip 2 comprises an internally threaded, externally tapered nut 6 encasedv within a tapered outer shell 1'. Parts `6 and 1' may be integral, but itv is convenient, for manufacturingy reasons, to use two parts, `especially when the exposed surface is to -be plated. Nut 6 serves to retain in the barrel the entire sub-assembly comprising the lead-propelling mechanism together with the lead storage magazine and pushbutton, which parts constitute, in the aggregate, a self-contained unit which can be inserted into'and withdrawn from the rear end' of thev barrel, being Aheld in place solely by nut 6. f

An elongate tube 8` forming a part of the aforementioned sub-assembly is disposed within barrel I, extending lengthwise thereof, and serves both as a lead storage magazine and as a connecting link between pushbutton 3 and the lead-propelling mechanism, which latter is contained wholly within the forward end ofthe barrel. rIfhe lead storage magazine is id'entied by reference numerals. 1 1

Tube 8 is formed with an enlarged diameter at its rear end to receive a sheet metal cup-like closure member It, together with pushbutton 3 which is also a cup-like member formed of sheet metal. The latter is spring-retained and slip fitted in the enlarged bore of tube 8 and can easily be withdrawn and reversed to expose an eraser II. Member II] is provided with a small axial opening ma through which sticks of lead are inserted into lead storage magazine 9.

When pushbutton 3 is depressed, tube 8 moves forwardly with it against the opposition of a coil spring I2.

Fixedly secured in the forward end of tube 8 is a plug I3 which is concaved at I3a for the purpose of guiding successive sticks of lead toward the axial borek I3b. Plug I3 is internally threaded at |30 to engage the externally threaded end I4a of a lead guide tube I4, which is shown most clearly in the sub-assembly view Fig. A6. It will be seen that tube I4 is, in eifect, a continuation of tube 8;-

Mounted on the threaded rear end` I4a of tube I4 is a nut I5 which serves to lock the connection between tube I4 and plug I3; and said nut is turned down to form a seat and'centering bossfor the rear end of spring I2.

A sleeve I 6 having an external thread IBa is held in place by nut 6 against ay shoulder Il formed in barrel I and is centered in the barrel by bore I8. A shoulder Ibi formed on'sleeve I6 provides an abutment for the forward end of spring I2, while the reducedportion Ic' serves as a guide to prevent said spring-buckling and thus possibly interfering'with4 the operation of the lead-propelling mechanism. The bore lof sleeve kI6 is conically tapered at Id to cooperate with the jaws of a clutch I9 which serves normallyto lock the writing lead and aids in the step-by-step forward movement thereof. Tube I4 is bored axially from end to end to form a conduit through lwhich sticks of lead are fed step-by-step from magazine 9, and said tube is split lengthwise at |419 to form spring fingers for yieldably gripping the lead. The mid-portion of tube I4 is reduced in diameter to form a shoulder at I4c whichlbears against a ring 20. The diameter of the forward portion of said tube is such as to afford a sliding t thereof in the bores of parts 6 and 1. Ring 2!! is a sliding fit on tube I4.

Clutch I9 is carried by tubefl'4 .and comprises a tubular sleeve portion I9a which encirclessaid tube and is in spring-pressedy frictional engagement therewith at |91, so that when not reu strained by external interference it will follow the lengthwise movements of said tube I4. In addition `to sleeve Illa, saidvclutch comprises a pain of oppositely disposed jaws |911 and IBc, which'preferably are integral with sleeve ISa and take the form of long'narrow arms resiliently anchored to sleeve 19a at points I9d and I9e respectively. Said arms are spring biased outwardly so that the jaws tend always to separate. Thevtwo jaws ISb andl I9@ extend respectively through two diametrically opposite elongate slots milled in tube I4 to eii'ect, jointly, a gripping or clutching engagement with writing lead 4. Normally, the lead is so gripped and thus restrained against retraction. The slots in tube I4 are longer than the clutch jaw portions which extend'through them and consequently itis possible for tube I'4 to move lengthwise relatively to clutch- I9 to a limited extent. rThe amount of this relative movement, as presently will appear.,

determines the distance the Writing lead is propelled forwardly in response to each full depression of the pushbutton.

The outer surfaces of jaws Iiib and Ito vare sloped lengthwise complementally to the conically tapered bore Ilid of sleeve I6. Thus, when the clutch, including said jaws, isforced backwardly as is normally the case, the jaws are contracted by sleeve It into clutching engagement with the lead. This is best illustrated in Fig. 2 from which it will be seen that clutch I9 is held against the conical bore of sleeve It by ring 20 which, in turn, is forced backwardly by tube I4, actuated by spring I2, through the medium of nut I5.

When pushbutton 3 is depressed, tube I4 is, as a result, pushed forwardly by tube S and plug i3 against the opposition of spring I2; and clutch I9 moves forwardly at the same time by reason of its frictional adherence to tube I4 and by further reason that for a time there is nothing'to interfere with such forward movement 'of the clutch. Jaws i921 and ISC are releasedfrorn the conical bore Id of sleeve l5 at the outset of .each forward movement and, because of theirvout-I wardly directed spring bias, they promptlydisengage the writing lead. Shortly thereafterring il) engages a shoulder 6a on nut 6 (see Fig. 3) and its forward movement is thereupon arrestedwhich, in turn, arrests the forward movement'of clutch I9. Tube I4 thereafter continues its forward movement until nut I5 strikesl the back end of clutch IS, as depicted in Fig. 3.

Since the writing lead is at all times lightly gripped by the front end of tube i4, it moves forwardly with said tube afterl being released from the restraint of the clutch jaws. l

When pushbutton 3 is released, following a full depressicn'thereof, tube I4 isimmediately re`` tracted'by spring I2 and, by reason of the aforementioned frictional adherence, between said tube and clutch I9, carries the latterwithfit. This results in also retracting the lead a short distance relatively to the barrel I but, presently, jaws 19d and Ic engage the conical bore Id of sleeve I5 (see Fig. 3) and are contracted thereby with sufficient force to engage the lead and hold it against further retraction while tube I4 continues its backward movement. The lead thereupon starts emerging fromthe frontend of tube i4. The backward movement of tube I4 is arrested when it reaches the point where ring 20 is gripped by the shoulder 94e and the front ends of jaws Iib and |90, as shown in Fig. 2.v The force of spring I2 then acting through tube I4 and ring 2!! upon jaws leb and IBc presses said jaws so firmly against the conical bore of'sleeve It that they are caused to contract and rmly grip the lead, thus preventing retraction thereof under writing pressure. ln fact the writing pres'- l sure exerted on the lead serves to increase the particularly advantageous in that there are no" interengaging moving parts which are susceptible of being clogged by. accumulations lof;-A

graphite dust; and this is. especially significant- :with respect to the tip end construction which :entails no telescoped relatively m'ovingp'arts, such yas are found in certain prior art lead feed mechn -anisms .f

f' v'We claim:

l. In a mechanical pencil, a barrel, :a lead guide tube extending axially of said vbarrel and 'having an-axial'bore forming a conduit for writing lead', said tube having at its forward portion means for `constantly exerting alight gripping actionon a lead therein so that it moves lengthwise with said tube except `when restrained by, external interference, said tube being reciprocable lengthwise of said barrel to a limited extent with said forward portion movable freely through the forward end of said barrel without abutment thereagainst, a spring continuously urging said tube rearwardly in the barrel'toward a position which it normally occupies, and a clutch for locking said lead against rearward movement under writing pressure, said clutch being operative in response to each forward movement of said tube and at the outset of each such movement to release the lead so 'that itis movable forwardly with said tube, said clutch being further operative in response to each rearward lmovement of said tube and prior to the completionof each lsuch movement to restrain the lead against further rearward movement whereby said lead is caused to emerge from the forward end of said tube.

2. In a mechanical pencil, a barrel, a lead guide tube extending axially of said barrel and having an axial bore forming a conduit for writing lead, said tube having means for continuously exerting uniform gripping action on a lead therein so that it moves lengthwise with said tube except when restrained by external interference, said tube being reciprocable lengthwise of said barrel to a limited extent, a spring continuously urging said tube rearwardly toward a position which it normally occupies; a clutch for locking said lead against rearward movement under writing pressure, said clutch being operative in response to each forward movement of said tube and at the outset of each such movement to release the lead so that it is movable forwardly with said tube, said clutch being further operative in response to each rearward movement of said tube and prior to the completion of each such rearward movement to restrain the lead against further rearward movement, said clutch comprising a sleeve mounted on said tube and friction ally adhering thereto and a plurality of fingerlike jaws each connected at one end to said sleeve and extending lengthwise of said tube,

spring ngers -for continuously exerting `al uniform gripping action on -said lead so that it moves lengthwise with vsaid tube except when restrainedby external interference, said :tube be ing reciprocable lengthwise of vsaid barrel to a limited extent, .and formed with its forward end of less .diameter than the end of said barrel whereby the forward end of said tube is vreciprocable through the forward end of said barrel without abutment against the end of said barrel a spring continuously urging said tube rearwardly of the barrel toward a position which it normally occupies, a clutch for locking said lead against rearward `movement under writing pressure, said clutch beingoperative in response to each forward kmovement of said tube and at the outset of each such .movement to release `the lead so that it is movable forwardly with said tube, said clutch being further operative in response to each rearward movement of said tube and prior to `the completion of each such movement to restrain the lead against further rearward movement whereby said lead `is `caused to emerge from the forward end of said tube.

4. Inamechanical pencil, .a barrel, a lead guide tube extending axially of -said barrel and having an axial bore ,forming a conduit for kwriting lead, the forward end portion of said tube projecting from said barrel and being split lengthwise to form spring fingers which continuously grip the lead sufficiently to hold it against gravity without locking the same against movement lengthwise of said tube, the gripping of the lead by said fingers being also sufiicient to cause the lead to move lengthwise with said tube when the lead is not restrained by the hereinafter-mentioned clutch, said tube being reciprocable lengthwise to a limited extent relatively to said barrel, a lead storage magazine connected with the rear end of said tube and reciprocable therewith, a clutch comprising a sleeve concentric with and encircling said tube and in frictional adherence thereto so that said clutch moves with said tube except when restrained by external interference, said clutch including a plurality of elongate jaws extending forwardly from said sleeve lengthwise of said tube and each connected at one end to said sleeve, said jaws being spring-biased outwardly from the axis of said tube, there being a, plurality of elongate slots in said tube through l, which said jaws extend individually for conthere being a plurality of lengthwise slots in said tube in registration with said jaws, respectively, and through which said jaws are movable to engage and disengage the lead in said conduit, said clutch being movable lengthwise along said tube to a limited extent, means operating to arrest the movement of said clutch during each forward movement of said tube, and means operative to contract said jaws into clutching engagement with the lead during each rearward movement of said tube and prior to the completion thereof whereby to arrest the rearward movement of the lead while the tube continues its rearward movement to completion.

3. In a mechanical pencil, a barrel, a lead guide tube extending axially of said barrel and hav,- ing an axial bore forming a conduit for writing lead, said tube being split lengthwise at its forward end to form a plurality of inwardly pressing jointly gripping said lead, a stationary sleeve disposed in said barrel and encircling said clutch, said sleeve being operative to force said jaws into gripping engagement with the lead when said clutch is .moved rearwardly and to release said jaws when said clutch is moved forwardly, a ring mounted on said tube in front of said jaws and slidable along said tube, said tube having a shoulder forming an abutment for said ring at the side thereof opposite said jaws, said tube being movable forwardly to a limited extent relatively to said ring and said clutch, and a spring for retracting said tube, said clutch being operative to arrest the rearward movement of said lead during a portion of each retractive movement of said tube, said tube being operative upon retraction to apply spring pressure through said ring to said clutch whereby to lock the lead against lengthwise movement.

5. A mechanical pencil comprising a barrel open at its forward end, a lead guide tube reciprocable in said barrel and having its forward end portion extending through and of less diameter than the opening in the forward end of said barrel wherebyit` is freely movable through said forward opening without abutment with the end of said barrel, said tube having means at its forward end portion for exerting a constant grip ona lead therein sufficient to cause the lead to move with the tube except when the lead is otherwise held against movement, a clutch in said barrel, actuating means for said clutch effective upon a predetermined rearward movement of said tube to cause said clutch to grip a lead in. said tube suiciently to hold the lead against rearward movement with said tube and against writing pressure, said clutch being released upon predetermined forward movement of said tube, spring means urging said tube rearwardly'in said barrel, and manually operable means projecting from said barrel for moving said tube forwardly in said barrel.

6. A mechanical pencil comprising a barrel open at its forward end and having a cylindrical bore portion adjacent its forward open end, a lead guide tube reciprocable in said barrel and having its forward end portion slidably guided in said cylindrical bore portion, and of less diameter than said forward open end whereby said tube is freely movable through said forward opening without abutment with the end of said barrel, said tube having means at its forward end portion for exerting a constant grip on a lead therein sufficient to cause the lead to move with the tube -eXcept when the lead is otherwise held against movement, a clutch in said barrel, actuating means for said clutch effective upon a predetermined rearward movement of: said tube to cause said clutch to grip a lead in said tube sufliciently to hold the lead against rearward movement with said tube and against writing pressure, said Aclutch being released upon predetermined rforward movement of said tube, spring means urging said tube rearwardly in said barrel, 'and manually operable means projecting from'said barrel for moving said tube forwardly insaidv barrel.

IVAN D. TEFFT.

MARLIN S. BAKER.

.REFERENCES CITED The following references are of record in the le^of this patent:

UNITED STATES PATENTS Number Name Date 1,592,502 Pollak July 13, 1926 1,742,711 Maloney Jan. 7, 1930 1,759,931 Barberon May 2-7, 1930 2,358,091 Lovejoy Sept. 12, 1944

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