US2703070A

US2703070A - Mechanical pencil

Info

Publication number: US2703070A
Application number: US189309A
Authority: US
Inventors: Musser C Walton
Original assignee: Prismatic Inc
Current assignee: Prismatic Inc
Priority date: 1950-10-10
Filing date: 1950-10-10
Publication date: 1955-03-01
Anticipated expiration: 1972-03-01

Description

C W. MUSSER MECHANICAL PENCIL March 1, 1955 Filed Oct. 10; 1950 4 Sheets-Sheet l v 1 1 I I I 1 I INVENTOR v C. wazion Masser:

ATTORN EYS vilw March 1 1955 0 c w. MUSSER 2,703,070

MECHANICAL PENCIL Filed Oct. 10, 1950 4 Sheets-Sheet INVENTOR C. Vt @5807! Mus-6e 7'.

March 1, 1955 c w. MUSSER 2,703,070

V MECHANICAL PENCIL Filed Oct. 10, 1950 4 Sheets-Sheet 3 fa l I /04 ma INVENTOR 4 E Walton Musser March 1, 1955 c w. MUSSER MECHANICAL PENCIL 4 Sheets-Sheet 4 Filed Oct. 10 1950 v INVENTOR C. Wmlon MIX-$86 7".

MECHANICAL PENCIL C Walton Musser, Philadelphia, Pa., assignor to Prismatic, Inc., Southampton, Pa., a corporation of Pennsylvania Application October 10, 1950, Serial No. 189,309

24 Claims. (Cl. 120-145) The present invention relates to mechanical pencils particularly of the character which select an indivldual color from a plurality of available colors of leads.

A purpose of the invention is to lock out unused colors by Wedge action, preferably of a segment which is selected and which carries the desired color of lead.

A further purpose is to move a lead-carrying segment radially toward the center by cam action preferably between a cam on a barrel and a cam on the segment.

A further purpose is to shape a segment to act as a ratchet on color selection in cooperation with a pawl or other ratchet element.

A further purpose is to move a nut to a limiting position on a helix and then to turn the nut without moving axially to bring a pawl into selective contact with individual ratchet surfaces on segments.

A further purpose is to align the segments in retracted position by engagement of aligning projections with an annular surface on the nut.

A further purpose is to provide selective engagement of a driving projection on the nut with a segment engaged by the ratchet.

A further purpose is to guide a segment during forward advance and retraction to prevent rotation and also prevent locked segments from advancing by gulding lands on a polygonal surface, desirably positioning one land outside the advancing segment and one land at each edge.

A further purpose is to construct a mechanical pencil barrel with a polygonal internal cross section and to posi-' tion a segment on each polygonal side.

A further purpose is to provide indexes on the, segments showing through a transparent barrel to indicate the amount of lead consumed and desirably also to act as stops on forward advance of the segments.

A further purpose is to utilize distinctively colored segments showing through a clear barrel to indicate the colors available and the colorsselected.

A further purpose is to employ individually colored segments in a transparent barrel having a hexagonal interior cross section, making each segment cross section approximately /6 of the hexagon, desirably providing only sufficient clearance to permit one segment to move radially inwardly and lock out the other segments.

A further purpose is to secure the tip in place by circumferentially spaced ribs on a reservoir which fit'in grooves on the inside of the tip when the tip is applied-1ongitudinally, and which engage with ribs on the inside of the tip when the tip is turned with respect to the reservoir.

Further purposes appear 'inthe specification and in the claims.

This application has been divided. The subject matter relating to the collet guiding has been included in application Serial No. 236,975, filed July 16,1951, for Collet Guiding in Mechanical Pencil. lating to the lead reservoir has been embodied in Serial No. 236,976, filed July 16, 1951, for Lead Reservoir for Mechanical Pencil.

The subject matter relating to the clip assembly is contained in Serial No. 236,977," led July 16, 1951, for Mechanical Pencil Employing Clip in Assembly."

In the drawings I have; chosen to illustrate a few only of the numerous embodiments'in which my invention may appear, selectingthe forms shown from the standpoints of convenience in illustration, satisfactory opera tion and clear demonstration 'of the-principles involved.

The subject matter re United States Patent 2,703,070 atented Mar. 1, 1955 2 ment of the invention partially broken away to show the reservoir for spare leads inside the tip.

Figure 2 is an exploded perspective, partially broken away, of the helix and nut assembly of Figure 1.

Figure 3 is an exploded perspective partially broken away, of the segments, collets and leads of Figure 1.

Figure 4 is an exploded perspective of the barrel, clip and tip of Figure 1.

Figure 5 is an axial section of the pencil of Figure 1.

Figure 5a is an enlarged fragment of Figure 5, with the collet compressed longitudinally in a lead-changing position. x

Figure 5b is an elevation of an alternate collet engaged on a segment and holding a lead.

Figures 6 to 9 inclusive are respectively sections on the lines 6-6, 7-7, 8-8 and 9-9 of Figure 5, to enlarged scale.

Figure 8a is an enlarged section corresponding to Figure 8, showing the segments in retracted position. The segments have been omitted in Figure 8 for clarity in illustration.

Figure 8b is a view corresponding to Figure Sabut showing one segment advanced and the other segments locked out.

Figure 9a is an enlarged section corresponding to Figure 9, omitting the leads in the reservoir and showing the selected segment further forwardly advanced, while omitting the other leads shown in Figure 9.

Figure 10 is an enlarged rear end elevation of the tip of Figure 1.

Figure 11 is an enlarged interior elevation, partially broken, of a segment, collet and lead of Figure 1 Figure 12 is a side elevation of Figure 11.

Figure 13 is an enlarged section of Figure 11 on the line 13-13, showing also the'helix and the nut in position for the pawl to pass over the ratchet face of a segment.

Figure 14 is a view similar to Figure l3, but showing an additional adjoining segment, with the pawl and driving projections in selecting position with respect to the first segment.

Figures 15 to 18 inclusive are enlarged sections of Figure 11 on the lines 15-15, 16-16, 17-17, 18-18 respectively.

Figure 19 is an axial section of a somewhat different embodiment of the invention.

element accomplishes color selection and propulsion and.

1y be made.

Figure 20 is an enlarged section on the line 20-20 of ment head, clip and band.

Figure 21 is an enlarged section on the line 21-21 of Figure 19, with all segments in retracted position.

Figure 22 is enlarged section on the line 22-22 of Figure 19.

'Figure 23 is an enlarged section of the tip and barrel alone on the line 23-23 of Figure 19.

Figure 24 is an inside elevation of an individual segment as seen in Figure 19.

Figures 25 and 26 are enlarged sections on the lines 25-25 and 26-26 respectively of Figure 24.

In the drawings like numerals refer to like parts throughout.

The present invention is directed to pencils in which a plural ty of colors are available, and especially to those in whlch a multiplicity of color selections can convenient- 'In the prior art, where a variety of colors have beenavailable for selection in a mechanical pencil,

the mechanism has been complicated and expensive and the operation has often been inconvenient or unreliable.

In accordance with the present invention, the same retraction of the selected lead. By motion of the color selecting element in one direction of rotation, ratcheting is accomplished over the various segments for individual colors, and by motion of the color selecting element in the opposite direction, the ratcheting parts prevent relative turning between the segment of the selected color and the ratchet and cause that segment to be pro- 0 pelled 'or repelled.

As an individual segment advances, the segments of Figure 1 is a Side elevation th'plefe'fred the unused colors are locked out by wedge action. The

. 3 locked out segments prevent the driving projection on the nut from leaving the driving recess of the forward segment until it is retracted. The advancing segment is moved radially toward the center on the start of forward motion to align the lead with the hole in the tip, and to exert the lockout action. A duohexagonal construction on the interior of the barrel guides the advancing segment against rotation, and also prevents longitudinal motion of the locked out segments.

The position of the propelling or repelling segment is visible through the transparent barrel by observing an indication on the segment, and this indication serves also to show the amount of lead available in the collet of that segment. The indication desirably provides a limitation on the forward advance of that segment.

The color of the segment viewed through the clear barrel also shows the color which is being used.

Provision is made inside the tip for storing of a reserve supply of leads, and the color of the individual leads stored is indicated by the angular position of the stored lead with reference to the corresponding color of one of the segments.

The assembly of the components is very conveniently accomplished by using the clip as a fastener to secure the helix to the barrel.

Considering first the form of Figures 1 to 18 inclusive, the pencil of the invention includes a barrel 40, a tip 41, a helix 42, a clip 43, a barrel band 44, a friction spacer 45, a nut or shoe 46, segments 47 and collets 48.

The barrel is very desirably made from a clear or transparent plastic, such as polystyrene or methyl methaerylate, and includes a generally tubular barrel portion 50, suitably of cylindrical exterior contour as shown, having a polygonal interior cross section 51 as best seen in Figures 6, 7, 8, 8a and 8b. The actual form shown is hexagonal to correspond with the six available colors, but it will be understood that any suitable polygonal agonal, heptagonal, octagonal, nonagonal or the like may be employed for the cross section.

The barrel interior maintains the same generally po- 4 drawing mold parts and also aids in guiding the propelled segment toward the center as later explained.

The sides 54 of the basic polygon in the cross section through the barrel portion 52 are longitudinally in line with the sides of the polygon in the portion of the barrel so that a segment sliding along the side of the polygon in the portion 50 will correspondingly encounter the side of a similar polygon in the portion 52.

An abrupt inward earn surface is provided at 58 between the sides of the polygon of portion 50 and of portion 52, desirably disposed at some steep angle to the axis preferably of the order of 45. As best seen in Figures 8 and 8b, this cam face is itself polygonal in end elevation and includes inwardly extending cam portions 60 on the ends of the lands 55.

The outside of the barrel portion 52 of reduced cross section has at positions corresponding to the sides of the basic internal polygonal cross section, grooves 61 extending longitudinally almost but not quite to the ends of the reduced barrel portion 52. Ribs 62 separate the grooves 61 and an annular portion 63 closes the forward ends. The rearward ends of the grooves 61 are closed by the cams 58.

The forward end of the barrel is provided with the tip 41 which is fastened to the barrel in any suitable manner preferably by a snap action as later explained. The tip has an inner bore 64 which surrounds the reduced portion 52 of the barrel, which then gradually tapers or converges at 65 toward a collet well 66 near the forward end which again tapers or converges at 67 into a center lead guiding opening 68 best seen in Figures 5 and 5a. The exterior portion of the tip gradually converges at 70 toward the forward end.

lygonal cross section from the rear end as shown in Figures 6 and 7 to a position approaching the middle as shown in Figures 8, 8a and 8b except that there is suitably a slight tapering convergence toward the forward end which aids in withdrawing cores, forces or plugs from the mold and which guides the propelled segment slightly toward the center as later explained. The amount of this taper may be comparatively slight. In an actual embodiment, for example, a convergence of 0.015 inch between the opposite barrel polygonal sides has been found to be adequate.

Forward of the generally uniform polygonal cross section as just described, a forward extension 52 is provided of reduced external and internal diameter as shown in Figures 4, 5, 9 and 9a. The reduced portion 52 of the barrel has an internal cross section 53 which is well shown in Figures 8, 8b, 9 and 9a and may be aptly described as duopolygonal or in the actual case duohexagonal, constituting as it does a hexagonal cross section within another hexagonal section for the purpose of guiding and propelling or repelling segment as later explained. The duohexagonal structure comprises basically polygonal sides 54 which are considerably closer together than the sides of the cross section 51, and, at the middle of each side, lands 55 which extend toward the interior of the cross section and extend longitudinally. In the preferred embodiment, where six sides are used (Figure 9a), the adjoining side 56 of each land 55 is desirably parallel with the adjoining side of the next land and also with adjoining sides of the opposite pair of lands, the sides 56 of the lands therefore being capable of functioning with the inner surfaces 57 of the lands as retaining and guiding surfaces for the propelling and repelling segment. The space be tween each pair of lands represents four sides of an incomplete hexagon having equal sides and angles of 120, within reasonable tolerance (as seen in Figure 911).

The interior cross section 53 desirably converges toward the forward end, so that the cross section tapers slightly, the amount of convergence of opposing sides 54 of the polygon being of the order of 0.016 inch in a particular example. The convergence aids in with- The rear end of the tip is preferably provided with a metallic tip band 71 which protects the tip against any tendency to stretch or split. The tip may be made of any suitable material, but it is generally preferable v to employ a plastic such as polystyrene, cellulose acetate, form such as triangular, rectangular, pentagonal, hexcellulose acetate butyrate, phenol-formaldehyde, ureaformaldehyde or the like rather than metal.

To render the tip readily removable and at the same time permit it to be inserted easily into position, the interior bore 64 of the rearward portion of the tip is provided with groove 72 as best seen in Figures 4 and 10 which correspond in placement to the positions of the ribs 62 and are sufficiently deep to allow the tip to slide longitudinally over the ribs without undue friction when the grooves 72 are aligned circumferentially with the ribs 62. Between the grooves 72 are flats or lands 73 which are comparatively shallow, suitably being of the order of a few thousandths of an inch, so that after the tip is inserted in place-on the barrel with the grooves 72 corresponding in position with the ribs 62, a slight twisting of the tip with respect to the barrel will lock the tip on the barrel by jamming the outer circumferential edge of the ribs 62 against the lands 73 on the inside of the tip.

The opening 68 in the forward end of the tip in many cases can be without metallic reinforcement, and therefore such reinforcement is not regarded as essential and has not been shown.

While the tip is shown applied by means of the grooves and lands, it will be understood that the tip may be i as shown.

The helix may be of any suitable material, but it is preferable to employ a plastic such as polystyrene, cellulose acetate, cellulose acetate-butyrate, phenol-formaldehyde or urea-formaldehyde rather than metal.

The forward end of the adjustment head '74 is shouldered at 80 as best seen in Figure 2 and between the shoulder and the screw portion 77 is located a hub 81 of reduced cross section compared to the head and which is suitably positioned immediately inside the rear end of the barrel. The hub has an annular outside groove 82 intermediate between the ends of the hub.

The barrel portion 50 at one position ,in the circumference as best scenin Figures 4 and 6,;hasv an inwardly extending slot 83 and is suitably provided with a recess 84 forward of the slot. The clip 43, suitably of resilient metal such as brass or bronze, has a base portion 85- which fits in the recess 84 and has atransverse tang 86 which extends through the slot 83 and at its inner end engages in the annular groove 82 on the hub 81of the helix. A suitable U-shaped resilient friction spacer 87 as best seen in Figures 2 and 6 is placed around the hub between the hub and the barrel with the open portion of the U spanning the tang 36. The spacer 8-7 frictionally engages the parts by an amount which is readily .predetermined, retards the helix against excessively free rotation in the barrel and prevents plastic-from running on plastic.

The press-fitting barrel band 44 surrounds the base portion 85 of the clip and holds the tang in position in the groove 82, and the tang prevents the helix from moving longitudinally as it turns with respect to the barrel.

A suitable indication 88, shown as a diamond, on the head 74, aids in orienting the helix for color selection as later explained.

The shoe or nut 46, as best seen in Figure 2, threads on the thread on the helix. The shoe has internal thread projections 90 which are in the embodiment shown of left hand thread character to correspond with the threads on the helix. As shown, the shoe is best formed from sheet metal or tubing of brass, bronze, beryllium copper or steel. I

A driving projection or dog 91 extends outwardly from the shoe at one position of the circumference preferably intermediate theends. At the rearward end of the shoe a resilient finger or pawl 92 extends outwardly circumferentially from the shoe as best seen in Figures 2, l3 and 14. The pawl is positioned for engagement in the clockwise direction of the motion of the helix as viewed from the rear toward the front of the helix. When the pawl selects, the selected segment corresponds in circumferential position with the diamond or other indication 88 so that the diamond will show what segment has been selected. The remainder of the rear end'of the shoe or nut provides an annular surface 93 except where it is broken by the outward projection of the pawl.

Positioned radially around the screw portion of the helix and around the nut are the segments or carriers 47, corresponding in number to the number of sides on the polygonal cross section 51 (in the present embodiment there are six shown). Each of the segments has (as best seen in Figures 5, l1 and 12), arear inward aligning projection 94 which engages behind the rearward circumferential edge 93 of the shoe when the shoe is in its rearward position. The segments also have a driving recess or groove 95 which receives the driving projection or dog 91. The cross section of the segment between the driving recess 95 and the aligning projection 94 is generally a fraction of thepolygonal cross section (one-sixth in the present case), with slight clearance for movement between segments, thus having as shown in Figures 7, 13 and 14 an outer edge 96 corresponding to one side of the polygonal cross section 51, and radial inwardly extending sides 97. The interior face 98 is a ratchet having a projection or high portion 100 in position to be engaged by the pawl when the motion is clockwise looking from the rear forwardly as in Figure 14, and having a low side 101 which permits the pawl to be cammed over the ,ratchet face 98 when the motion is counterclockwise when viewed from the rear toward the front as in. Figure 13.1 p

In effect the rearward portion of the segment which provides the ratchet, the driving recess and the aligning projection is in the form of a head 102' which is sufficiently thick in radial dimension to occupy practically the entire space between the screw portion of the helix and the inside of the barrel.

Forward of the driving recess- 95 the segment is reduced in segmental width by diagonal corner cut-offs 103 (120 angles included) as best seen in Figure 16, the sides 97 still being generally radial but not extending fully to the outer corners, and the outer polygonal side 96 being narrowed by the corner cut-off. Theinner surface 104 is conveniently the arc of a circle whicl; extends to the forward end of the'driving recess 5.

In the forms shown in Figure 16 the angle between the two sides 97 of thesegment is desirably 60?;

The cross section of Figure 16 of the segment has a slight clearance or is slightly less than one-sixth of the hexagon so that the individual segment which is be ing propelled or repelled can move readily inwardly as later explained. I

The guiding portion 105 of the segment which has just been described is joined to the head 102 by a suitably diagonal (preferably 45 to the axis) cam surface indication 106 as best seen in Figures 11 and 12, which performs the dual function of showing the position of advance of the segment through the transparent barrel and serving as a stop for the advance of the segment as later explained.

The segment toward its forward end is inwardly ofiset at 107, preferably at an angle of about 45 to the axis, producing an outer cam surface which cooperates with the cam surface 58 on the barrel. Forward of the ofiset 107 a forwardly tapering circular cross section 108 is provided which reduces at the forward end to approximately the diameter of the lead. The forward end 108 extends diagonally toward the center and assists in directing the lead to the center of the tip.

The manner by which the lead is held on the forward end of the segment, or specifically the collet which is used, forms no part of the present invention, the particular collet construction illustrated in the preferred embodiment being the subject matter of Jacobsen and Jacobsen copending application Serial No. 203,522, filed December 29, 1950, now Patent Number 2,624,313 for Mechanical Pencil and Collet Therefor. In this particular form the collet comprises a spiral spring 110 which surrounds the forward tapering end 108 of the segment and also surrounds and grips the lead 111. As later explained, the collet can be compressed longitudinally by engaging the inside of the cam faces 67 in the collet well 66, and when thus compressed will release the lead as shown in Figure 5a. Correspondingly when a lead is positioned against the forward end of the segment and the collet is then released it will surround and grip or pick up the new lead. Or the new lead can be introduced into the expanded collet with a rotary screwing motion.

Any other suitable collet may be used. For example as shown in Figure 5b a resilient metallic tubular collet 48 may be employed, having slits 110' and 110 running from the ends nearly to the middle for resilience.

As best seen in Figure 9a, when the segment is well advanced its guided portion 105 engages and is guided in the duohexagonal interior of the barrel portion 52. In this position, the sides 97 of the segment engage the sides 56 of two spaced lands, while the corner edges 103 engage the basic polygonal sides 54 of two spaced sides of the polygon. The outer portion 96 of the segment engages the inner surface 57 of the intermediate land 55. The segment is thus guided and imprisoned against movement out of the desired path. The segment over the guided portion 105 may if desired slightly taper to con form with the slight taper on the interior of the duopolygonal cross section.

Each individual segment is desirably made from plastic such as polystyrene, methyl methacrylate, cellulose acetate or acetate-butyrate, phenol formaldehyde or ureaformaldehyde, colored or coated to have the same color as the lead carried by its collet, and the lead in the storage groove 61 at the same radial position is desirably also of the same color. This is especially important as it is often impossible to tell from the exterior appearance of the lead (without causing the lead to write) whether the lead is one of several colors which resemble one another. Except for the difference in color (see colors in section on Figure 7) the segments can be identical.

In operation of the form of Figures 1 to 18 inclusive, the device is assembled by threading the shoe on the helix, and running it up the helix close to the rear end. The collets are mounted on the segments. The various segments are then placed around the helix with the aligning projections against the rear end of'the shoe, and the driving projection in one of the driving recesses. The spacer 87 is slipped over the hub 81 as by springing from the side, and then the barrel is slipped over the segments, the helix and the spacer, turning the barrel until the barrel slot 83 corresponds in position with the open side ofthe spacer.- T he tang ofthe clip is then inserted through the 7 slot 83 and into the annular groove 82 on the hub of the helix. The barrel band 44 is then pushed over the head of the helix into place around the base of the clip.

Spare leads corresponding in color to the colors of the segments are then placed in the grooves 61 of the forward portion of the barrel at the proper radial positions, and while the leads are held in the grooves the tip is slipped over the forward end of the barrel, being careful to align the grooves 72 on the tip with the ribs 62 on the barrel. When the tip has moved up as far as permitted toward the rear of the barrel, the tip is locked in place by rotating it with respect to the barrel.

The eraser is then conveniently forced in the socket of the head of the helix.

The individual collets can be loaded in the following manner. Starting with any segment the helix is turned clockwise as viewed from the rear toward the front as shown in Figure 14, and the pawl engages the ratchet of a particular adjoining segment, the segment being identifiable by the fact that the indication 88 on the outside of the head of the helix lines up circumferentially with the particular segment being selected. The pawl prevents the shoe from turning as the helix is turned clockwise in Figure l4 and since the shoe cannot turn as the helix turns the particular segment whose driving recess 95 is engaged by the driving projection or dog 91 on the shoe is advanced forward. As soon as this propelled shoe begins to advance, the outer cam surface on off-set portion 107 of the segment engaging the inner cam surface 58 on the barrel forces the forward end of that segment inwardly as shown in Figure 5. The forward end of the guiding portion 105, being forced inwardly, is progressed in guided relation to the duopolygonal cross section of the interior of the barrel as shown in Figure 9a, firmly positioning and guiding the guided portion 105 of the propelled segment. At the same time. as shown in Figure 8b, the guided portion 105 which when radially outward has freedom laterally at 112 (Figure 8a) with respect to the other segments, now moves inwardly and wedges or jams the other segments outwardly, thus locking all other segments in the outward position (Figure 8b). Thus whereas formerly there was freedom at 113 between the barrel and the outside of the other segments, the other segments are now forced tightly against the barrel at 113' (Figure 8b). Also the other segments, which as shown in Figure 8a are narrower at the outside than the polygonal interior of the cross section, are crowded over slightly off-center away from the inwardly wedging segment 114.

As seen in Figure 8b the corner cut-offs 103 of the two segments on either side of the wedging segment permit those segments to engage remote sides of the hexagon in common. with the segments normally placed at such remote sides and thus provide room for the propelled segment to move inward.

I find it desirable to thicken the segments radially in Figure 81) (at the forward ends of the portion 105) by a few thousandths of an inch so that the propelled segment will flex or distort the helix 42 slightly from the center and thus tend to assure firmer contact with the shoe as the helix moves forward.

The outward wedging action on the other segments assures that the cam portions at the off-sets 107 are firmly engaged against the interior cam portions 58 on the barrel, so that the other segments are effectively locked out and unable to move forward.

As the forward moving segment advances with its guided portion 105 in the duohexagonal part of the barrel the collet moves into alignment with the center and eventually travels down the collet well 66 until it engages the cam surface 67 at the inside of the tip around the lead opening 68. The collet becomes compressed on the tapered portion 108 of the forward end of the segment as shown in Figure 5a, but has a tendency to expandforwardly when released. If now a lead 111 is inserted through the lead opening in the tip and the segment is retracted, the collet will expand longitudinally and also contract radially and grip the lead, achieving the position shown'in Figures 5, ll and .2. If preferred the segment may be retracted enough to expand the collet and the lead may be screwed or turned into the collet through the opening 68.

In order to retract the lead, the helix is turned counterclo'ckwise looking toward the front from the rear, which causes the'shoe to move rearwardly on the helix without turning. The projection 91 is prevented from turning due to engagement with the side of a locked out segment. As the segment moves up or down, the head 1.02 of the segment rides against the polygonal side of the interior of the barrel cross section, preventing the segment from moving outwardly from the shoe. At any position the segment position is shown outside the barrel by viewing the edge 106 through the transparent barrel. When the segment is fully advanced the engagement of the edge 106 against the interior cam surface 58 on the barrel acts as a stop against further advance.

As the segment is retracted it continues to move rearwardly without turning due to the engagement of the projection 91 with the sides of the next locked out segment until it encounters the aligning projections 94 on the various segments which are in rearward position. The segment which is just being retracted is brought into fully retracted position by the contact of the rearward edge of the shoe with its own aligning projection and all segments are held in rearward aligning position by their aligning projections contacting the rear of the shoe. On further turning of the helix counterclockwise as viewed from the rear toward the front the shoe is prevented from moving rcarwardly as it is already in its full rearward position (since the threads on the helix stop at this point and prevent further longitudinal or rotational motion of the shoe with respect to the helix), and the shoe begins to ratchet or move its pawl over the ratcheting surfaces of the segments as best seen in Figure 13.

The pawl enters each segment at the wide spaced edge 10]. and is drawn over the ratchet face of the segment toward the close spaced edge 100, while at the same time the pawl is forced toward the axis due to its resilience. This ratcheting action is accompanied by clicking as the pawl passes from one segment to the next, indicating to the user the number of segments over which he is turning. At the same time the indication 88 on the head of the helix lines up with a particular segment which is in selection position at any moment, so that the user can simply watch the colors of the segments and turn until the diamond or other indication 88 is in line with the segment of the desired color. At this point the user reverses the direction of rotation, turning clockwise when viewed from the rear toward the front as in Figure 14, and beginning the forward motion of the particular segment.

The above procedure can be employed successively to introduce lead into the collet of each segment, and also to accomplish the selection of the particular color which is to be used after the collets are filled. During use of the pencil, the collet well 66 tends to guide the collet and prevent the lead from wobbling.

The form of Figures 19 to 26 inclusive illustrates a variation which however possesses many features present in the form previously described. in this latter form the barrel 40 is of transparent plastic as previously described, and is provided with a comparatively short forward extension 52 which makes a force or other fit with a tip 41' which is generally similar to the tip previously described. No provision is made for storing leads inside the tip in this form, but instead the helix 42 has a hollow interior reservoir 115 which is accessible for removing the eraser 76 from the helix head 74. The manner of assembling the helix to the barrel by the tang on the clip is the same as that previously described except that the spacer 87 is omitted as unnecessary.

In this form each segment 47' has interior thread notches 116 which engage threads 78 protruding from the forward end portion only of the helix. The helix tapers at 117 and toward the forward end the threads themselves taper as shown. The barrel interior construction is somewhat different from that shown in the other form. The rear portion of the barrel interior is round as shown in Figure 20. From the round cross section the barrel tapers inwardly preferably on the same taper as the helix at 118 to achieve a polygonal interior cross sec tion as shown in Figure 21, where the fully retracted segments have lateral freedom at 112 as previously described. Forwardly of the point 1.18, however, the barrel interior is substantially straight and hexagonal at 121 as shown in Figure 22 until the cam portions 58 are encountered. Forward of the cam portions 58, the duohexagonal portion 52is1interiorlyas previously described. The segments have the otf-setportions 107' and the forward 9 tapering extensions 108 which engage thecollets 48 as already described. a '3 The segments preferably have curved outer walls 122 on the recesses between teeth as shown 'in Figure 25, but the interior edges of the teeth 123 as shown in Figure 26 are preferably straight to aid in ratcheting into and out of the threads on the helix.

It will be evident that retracted segments when not mating with the threads 78' at the end of the helix are flexed or bowed to conform with the tapered portion 118 and the straight portion 121 of the barrel interior due to the force exerted by thread land 124 of the helix on thread land 125 of the segment (Figure 19).

In this form the ratchet is accomplished by the spring of the segments with respect to the helix. As long as all of the segments are in the rearward position, when the helix is turned counterclockwise as viewed from the rear toward the front, the threads on the helix move successively into engagement with the thread notches of successive segments as the helix turns, anclas thecounter clockwise motion is continued the thread lands in the helix force the particular segment outward as shown at 124, 125. The thread on the helix then mates with the thread on the next segment with a clicking noise and a ratcheting action as the counterclockwise motion. continues. Whenever one segment engages with the helix the spring of the material (plastic) makes that segment move in, as shown at 126 in Figure 22, locking all other segments out, and bringing cut corners 103 of adjoining segments over to the sides of the hexagon as earlier explained.

When the helix is turned clockwise while the engagement with the thread notches of a particular segment is complete, that particular segment is advanced and as it moves forward is moved further inwardly by the action of the cam surface 58 of the barrel on thevstep portion 107' of the segment. The forward portion of the segment is now guided on the inside of the duohexagonal portion. 52 as earlier explained. This action feeds the lead through the lead opening in the tip, and if continued far enough will release the lead from the collet by longitudinally compressing the collet.

A counterclockwise motion will retract the segment until it is in. rearward position in line with .the other segments. Whenever one segment is advanced and moves inwardly the wedge or lock-out action of its wedge cross section causes the othersegments to .be pushed toward the outside of the barrel interior and prevents engagementof the helix threads with the other segments as shown in Figure 22. In this form it is necessary to use the rear end of the segment viewed through the transparent barrel as an index of the segment position and of the expenditure of lead.

. When the segments are all in the rear position, further counterclockwise motion causes ratcheting for selection of .a different segment. The helix head has an index 88, not shown, as in the other form.

It will be evident that in the present invention the segments are shaped for ratcheting with the helix or pawl on the shoe to permit selection of aparticular color. The segment when it moves inwardly locks out the other segments by wedge action and is itself camrned into alignment with the hole in the tip. I

The segment as it advances or retracts is guided by the 1gluoptlflygonal cross section of the forward part of the arre r The user can view the color selected through the transparent barrel and can also view-the amount of lead available by the indication of the segment position when the lead comes-through the' front of the tip;

Provision is made in the helix for a reservoir and'in the case of the barrel reservoir the device indicates the color of the lead stored at each position.

The assembly is facilitated by using the tang of the clip to retain the parts in assembled relation and to permit relative rotation of the helix with respect to the barrel.

. In view of my invention and disclosure variations'and modifications to meet individual whim or-particularneed willdoubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all ,such insofar as they fall within the reasonable spirit 86 and scope of my claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is: 1. In a mechanical pencil, a barrel having a polygonal interior cross section, segments one for each polygonal side extending through the barrel at the point of poly gonal cross section, all but one engaging the polygonal sides, the segments engaging one another on-the radial edges when one segment moves inward, and having only suflicient freedom for inward movement of one segment at a time, leads carried by thesegments and means for selecting and advancing an individual segment and moving that segment toward the center of the polygonal cross section, whereby other segments are locked in outer posiion.

2. In a mechanical pencil, a barrel having an' interior open portion, segments occupying the interior open portlon of the barrel in engageme'nt with the inside of the barrel in one position, having wedge cross section and having only sufiicient freedom to permit inward movement of one segment at a time, leads carried on the forward ends of the segments, means for selecting and forwardly moving one segment at a time and cam surfaces cooperating between the barrel and the advancing segment for moving the advancing segment inwardly and thereby locking out all other segments.

3. In a mechanical pencil, a barrel having a polygonal interior cross section, segments extending through the interior of the barrel having wedge cross section and hav- 1ng only sutficient freedom in the barrel to permit one segment to move inwardly and thereby lockout other segments, leads mounted on the forward ends of the segments, a rotatable helix extending longitudinally through the barrel radially inwardly of the segments, ratchet mechanism interposed between the helix and the segments for selecting an individual segment and then advancing that segment along the helix and cam surfaces cooperating= between the segments and the barrel for moving an individual segment inwardly as it is advanced forward.

4. A mechanical pencil, according to claim 3, in which there are corner cut-offs in cross section on each of the segments which, when the segment is locked out, fit into a polygonal side of the barrel adjoining the side normally engaged by that segment.

5. A mechanical pencil, accordingto claim 3, including means cooperating between the helix and the segments for selecting an individual segment and advancing and retracting it, the segments when in advanced positionextending inwardly at the forward end of the helix sufficient to distort the helix slightly off center away from the advancing center.

6. A mechanical pencil, according to claim 3, in which the segments have screw notches on their interiors and a helix extends through the barrel from the rear end inside the segments and has threads on the forward end in combination with means for flexing the segments so that their forward ends spring into ratchet engagement with the threads on the helix.

7. A mechanical pencil, according to claim 3, in which the barrel has a hollow interior which is of tapered polygonal cross section from a point near the rearward end to a point forwardly, and which is of less sharply tapering corresponding polygonal cross section toward the forward end of the point last mentioned, the segments are resilient and have thread notches on the interior and a helix is rotatably mounted on the center of the barrel tapering externally from the rear, converging toward the forward end and having helix threads on the forward end which engage a ratchet on the thread notches in the segments.

8. A mechanical pencil, according to claim 3, in which the barrel has a portion of hollow interior polygonal cross section which tapers convergingly from the rear to an intermediate point and then extends with generally straight polygonal cross section forwardly, there is a duopolygonal cross section forward of the cams provided with inwardly guided extending lands, a tip is provided forming a central tip openings forward of the duopolygonal cross section, the segments are resilient and have thread notches on the interior surfaces, and the helix is externally forwardly convergingly tapering rotatably supported in the barrel at the rear end extending forwar'dly in the barrel and provided; with external helix threads toward the forward end which engage a ratchet with the thread notches of the segments,; the taper of the helix toward the rear end contacting and distorting segments outwardly so that the forward ends of the segments tend to .spring inwardly and engage the threads on the helix, and the individual segment, when advanced and moving inwardly, being guided on the duopolygonal cross section of the barrel.

9. In a mechanical pencil, a barrel having a polygonal interior cross section, segments one for each polygonal side extending through the barrel at the point of polygonal cross section, all but one engaging the polygonal sides, one segment moving inwardly and bringing all segments into engagement at the radial edges and having only suflicient freedom for inward movement of one segment at a time, leads carried by the segments, a tip on the barrel having .a central lead opening, cam surfaces cooperating between the barrel and the advancing segment for deflecting the advancing segment inwardly to align the lead with the lead-opening in the tip and means for selecting and advancing an individual segment and thereby locking out other segments.

10. In a mechanical pencil, a barrel having a polygonal interior portion of comparatively large inside diameter, a polygonal portion of smaller inside diameter toward the forward end and sloping cam surfaces between the portion of the larger inside diameter and the portion of the smaller inside diameter, segments one for each polygonal side extending through the barrel at the portions of polygonal cross section, all but one engaging the polygonal sides, when one segment moves inward the radial edges of all other segments being in engagement and having only sufficient freedom for one segment at a time, the segments having cam suf-aces cooperating with the cam surfaces on the barrel to deflect an individual forwardly advancing segment inwardly, means for selecting and advancing an individual segment and means for mounting leads on the individual segments.

11. In a mechanical pencil, a barrel having a polygonal interior portion of larger diameter, a more forwardly located polygonal portion of smaller interior diameter and interior .cam portions between the portions of larger and smaller interior diameter, a tip having a central lead opening connected to the barrel at the portion having a smaller interior diameter, a plurality of segments normally occupying the outer part of the interior portion of larger interior diameter, there being one segment for each polygonal side, all but one of the segments engaging the polygonal sides, one segment on moving inwardly causing the radial edges .of all segments to be engaged and there being only sufiicient freedom for inward movement of one segment at a time, the segments having cam surfaces cooperating with the cam portions on the interior of the barrel, means for mounting lead on the forward ends of the segments, a helix extending through the center of the portion having the larger interior diameter and means moving on the helix for selecting a particular segment, moving it forward and thereby camming it inwardly so that the forward edge is in line with the lead opening on the tip.

12. In a mechanical pencil, a barrel having a polygonal interior portion of larger interior diameter, a more forwardly located polygonal interior portion of smaller interior diameter and interior cam portions between the portions of larger and smaller interior diameter, a tip having a central lead opening connected to the barrel at the portion having the smaller interior diameter, a plurality of segments, one for each polygonal side extending through the barrel, all but one engaging the polygonal sides, one segment on moving inwardly bringing the radial edges of all segments into engagement, there being only suflicient freedom for inward movement of one segment at a time, and the segments having cam surfaces cooperating with the cam surfaces on the interior of the barrel, means for mounting lead on the forward end of the segments, a helix extending through the center of the portion having the larger interior .diameter, and means acting between the segments and the helix for selecting a particular segment, moving it forward and camming it into line with the lead opening in the tip, and then for retracting it and selecting another segment.

13. In a mechanical pencil, a barrel having an interior portion of larger poly-gonal cross section, a portion .of smaller interior polygonal cross section toward the forward end of the barrel with respect to the portion of larger cross section and internal cam surfaces connecting the 12 polygonal portions, a tip having a central lead opening on the barrel at the forward end, segments extending through the interior of the barrel corresponding in number to the number of polygonal sides on the interior of the barrel, and occupying only enough less than the space around the outer portion of the interior to permit locking of all segments in outer position when one segment moves inwardly, cam portions on the segments toward the forward ends cooperating with the cam portions on the barrel, means for holding lead on the segments at the forward ends, and means for selecting a particular segment, for advancing it forwardly and moving it inwardly to align with the center of the tip by the cam action.

14. In a mechanical pencil, a barrel having an interior portion of larger polygonal cross section, a portion of similar interior polygonal cross section toward the forward end of the barrel with respect to the portion of larger cross section and internal cam surfaces connecting the polygonal portions, a tip having a central lead opening on the barrel at the forward end, segments extending through the interior of the barrel corresponding in number to the number of polygonal sides on the interior of the barrel, and occupying only enough less than the space around the outer portion of the interior to permit lock-ing of all segments in outer position when one segment moves inwardly, cam portions on the segments toward the forward ends cooperating with the cam portions on the barrel, means for holding lead on the segments at the forward ends and means including a helix extending through the barrel and operating on the inner edges of the segments for selecting a particular segment, advancing it forwardly and moving it inwardly by the cam action.

15. In a mechanical pencil, a barrel having an interior portion of larger polygonal cross section, a portion of smaller interior polygonal cross section toward the forward end of the barrel with respect to the portion of larger cross section and internal cam surfaces connecting the polygonal portions, a tip having a central lead opening on the barrel at the forward end, segments extending through the interior of the barrel corresponding in number to the number of polygonal sides on the interior of the barrel, and occupying only enough less than the space around the outer portion of the interior to permit locking of all segments in outer position when one segment moves inwardly, cam portions on the segments toward the forward ends cooperating with the cam portions on the barrel, means for holding lead on the segments at the forward ends, an adjustment helix rotatably mounted and extending through the interior of the larger portion of the barrel, a nut threaded on the helix, a projection on the nut engaging the interior of any one of the segments and ratchet means between the nut and the segments for selecting an individual segment.

16. In a mechanical pencil, a barrel having a longitudinally extending interior opening, a helix extending through the opening and having an adjustment head rotatable with respect to the barrel and extending outside the barrel, there being an internal shoulder on the adjustment head at the end of the helix adjoining the adjustment head, segments disposed around the interior of the barrel outside the helix having internal ratchet faces, internal aligning projections and internal driving recesses, a nut threaded on the helix, a driving projection on the nut selectively engaging the driving recess of an individual segment, a pawl on the nut selectively cooperating with the individual ratchet faces, an annular surface on the nut cooperating with the aligning projections, the segments having clearance which is only great enough to permit one forwardly advancing segment to move inward and thus lock the others in outer position, cam surfaces between the barrel and the segments for moving the forwardly advancing segment inwardly, and means on the forward ends of the segments for mounting leads.

17. In a mechanical pencil, a barrel having an enlarged polygonal interior portion and a polygonal portion of reduced diameter with guiding and locking lands extending inwardly from each side from the polygonal cross section, segments, one for each polygonal side, extending through the polygonal portion of the interior of the barrel, all but one engaging the polygonal sides, one segment on moving inwardly causing the radial edges of all other segments to engage, having only suflicient freedom for inward movement of one segment at a time, and an individual segment when it advances. being guided and locked by the lands, means for selecting and advancing in dividual segments while holding other segments locked out and means on the forward endson the segments for supporting leads.

18. In a mechanical pencil, a barrel having an internal polygonal portion of large diameter, an internal polygonal portion of smaller diameter provided with guiding lands extending from the polygonal sides and cam portions between the larger and smaller portions, segments one for each polygonal side extending through the polygonal portion of larger internal diameter, all but one engaging the polygonal sides, one segment on moving inwardly bringing the radial edges of all segments into engagement, there being only sufficient freedom for inward movement of one segment at a time, and there being cam portions on the segments cooperating with the cam portions on the interior of the barrel, the segments in forward position being guided by the lands, a helix extending through the interior of the barrel and ratchet and driving means carried by the helix for selecting individual segments and advancing and retracting the individual segments.

19. In a mechanical pencil, a barrel having an open interior which is enlarged and of polygonal cross section near the rear end and which is of smaller diameter and of polygonal cross section near the forward end with lands extending from the middles of the polygonal sides for guiding and locking the segments mentioned below, and having cam portions on the interior of the barrel between the larger and smaller polygonal cross sections, segments in the barrel having cam portions which cooperate with the cam portions on the barrel, and having clearance which is only suflicient to permit one segment at a time to move inwardly while locking out other segments, the forward portions of the segments riding over one land at the outside and locking under the edges of two lands, means for supporting lead on the ends of the segments, ratchet surfaces on the inner edge of each segment, and means including a driving interconnection to a selected segment and ratchet mechanism which selects an individual segment and advances and retracts it 20. In a mechanical pencil, a barrel having an open interior which is enlarged and of polygonal cross section near the rear end and which is of smaller diameter and of polygonal cross section near the forward end with lands extending from the middles of the polygonal sides for guiding and locking the segments mentioned below, and having cam portions on the interior of the barrel between the larger and smaller polygonal cross sections, segments in the barrel having cam portions which cooperate with the cam portions on the barrel, and having clearance which is only sufiicient to permit one segment at a time to move inwardly while locking out other segments, the forward portions of the segments riding over one land at the outside and locking under the edges of two I lands, means for supporting lead on the ends of the segments, ratchet surfaces on the inner edge of each segment, a driving recess on the inside of each segment, an aligning projection on the inside of each segment near the rearward end, a helix extending through the barrel on the inside of the segments and having an adjustment head provided with an annular shoulder located rearwardly of the segments, a nut threaded on the helix, a driving projection on the nut engaging the driving recess of a selective segment, a pawl on the nut selectively contacting the ratchet surfaces on the individual segment and an annular edge on the nut contacting the aligning projections in rearward position on the segments.

2-1. In a mechanical pencil, a barrel having an interior portion of polygonal cross section toward the rearward end, having an interior portion of smaller polygonal cross section toward the forward end and provided with guiding lands extending inwardly from each polygonal side, the polygonal sides in the larger and smaller portions being longitudinally aligned, and having cam portions for each polygonal side between the larger and smaller portions, a tip secured to the barrel toward the forward end and having a central lead opening, a plufaces on the barrel and limiting forward motion of the at a time, the segments having cam portions-which cooperate with the cam portions on the barrel to move an individual segment inwardly as it moves forward, having driving recesses at their interiors, having interior ratchet faces, and having aligning projections at their rearward ends, a helix extending through the barrel from the rearward end and having an adjustment head at the rearward end provided with a select-or index which is'coordinated with the position of the pawl, the helix having an annular shoulder inside the barrel, a nut threaded on the helix and movable along the same when rotationally stationary, a driving projection on the nut selectively e11- gaging the driving recess on an individual segment, a pawl on the nut selectively engaging the ratchet surfaces on the individual segments, an annular surface on the nut engaging the aligning projections on the segments in rearward position of the segments, the segments in forward position guiding on one land at the outside and under two lands at the edges and means on the forward ends of the segments for supporting a lead.

22. In a mechanical pencil, a barrel having an interior portion of polygonal cross section toward the rearward end, having an interior portion of smaller polygonal cross section toward the forward end and provided with guiding lands extending inwardly from each polygonal side, the polygonal sides in the larger and smaller portions being longitudinally aligned, and having cam portions for each polygonal side between the larger and smaller portions, a tip secured to the barrel toward the forward end and having a central lead opening, a plurality of seg ments, one for each polygonal side disposed around the outside of the interior of the barrel, the segments being of wedge cross section with only sufficient clearance so that only one segment can be forced inward at a time, the segments having cam portions which cooperate with the cam portions on the barrel to move an individual segment inwardly as it moves forward, having driving recesses at their interiors, having interior ratchet faces, having aligning projections at their rearward ends, and having offset portions at the outside of the segments adjacent the nut of the selected segment for engaging the cam sursegments, a helix extending through the barrel from the rearward end and having an adjustment head at the rearward end provided with a selector index, which is coordinated with the position of the pawl, the helix having an annular shoulder inside the barrel, a nut threaded on the helix and movable along the same when rotationally stationary, a driving projection on the nut selectively engaging the driving recess on an individual segment, a pawl on the nut selectively engaging the ratchetjsurfaces on the individual segments, an annular surface on the nut engaging the aligning projections on the segments in rearward position of the segments, the segments in forward position guiding on one land at the outside and under two lands at the edges and means on the forward ends of the segments for supporting a lead.

23. In a mechanical pencil, a barrel having a hollow polygonal interior, segments in the barrel, one for each polygonal side, having only sufiicient clearance so that when one segment is forced inwardly the other segments are locked outwardly, each of the segments having corner cut-offs in cross section which, when the segment is locked out, fit into a polygonal side of the barrel adjoining the side normally engaged by that segment, leads mounted on the forward end of each segment, and means for selecting, advancing and inwardly moving a particular segment, and retract-ing the same.

24. In a mechanical pencil, a barrel having a hollow polygonal interior, segments in the barrel, one for each polygonal side, having only sufiicient clearance so that when one segment is forced inwardly the other segments are locked outwardly, each of the segments having corner cut-offs in cross section which, when the segment is locked out, fit into a polygonal side of the barrel adjoining the side normally engaged by that segment, leads mounted on the forward end of each segment, a helix extending through the interior of the barrel inside the segments and means ratcheting on the interiors of the segments cooperating with the helix for selecting a particular segment, advancing it and forcing it inwardly and retracting it.

(References on following page) References Cited in :the file of this patent UNITED STATES PATENT-S Smith Jan. 3, 1 893 Patten Aug. 4, 1925 5 Opp June 10, 1930 Ba-rany May 15, 1934 Esterow Mar. 2-4, 1936 Hanson Feb. 18, 194 1 Senf Apr. 1, 1941 10