US2106389A - Mechanical pencil - Google Patents

Description

Jan. 25, 1938. w. H. BLAKE MECHANICAL PENCIL Filed 001;. 20, 1936 INVENTOR WILLIAM H. BLAKE ATTORNEYS Patented Jan. 25, 1938 UNITED s'rATEs PATENT OFFICE 20 Claims.

The present invention relates to mechanical pencils and embodies, more specifically, an improved form of pencil by means of which the feeding or retracting of the lead is facilitated, as well as incorporating further improved features which materially increase the utility of the device and convenience thereof in use.

More particularly, the present invention is an improvement on the device shown and described in applicants prior Patent No. 1,204,336 dated November 7, 1916, the present invention embodying additional improved features which serve to render the pencil more useful and effective in operation. As typifying the development of the art as it now exists, in the type of pencil described herein, the structure shown in applicants prior patent is incorporated herein with changes in structure adapting it to include a more effective lead feeding and retracting device, as well as a means for discharging, automatically, the lead from the lead carrier when the latter has advanced to the end of its travel. There is further incorporated an improved locking means by virtue of which the operation of retracting the lead does not disassemb-le the parts of the pencil and further provision is made for an improved form of cap which is well suited to hold an eraser .and clip upon the extremity of the lead magazine.

An object of the invention, accordingly, is to provide an improved form of mechanical pencil, such pencil being adapted to eject the lead from the lead holder upon a predetermined travel thereof in the feeding direction.

A further object of the invention is to provide a device for transmitting rotary motion to the lead holder, such device being formed of a plurality of units which may be taken down and readily assembled, an improved form of locking mechanism being incorporated in this structure to prevent the disassembling of the units during the retracting of the lead holder.

Further objects, not specifically enumerated above, will be apparent as the invention is described in greater detail in connection with the accompanying drawing, wherein:

Fig. 1 is a view in axial section taken longitudinally through a pencil constructed in accordance with the present invention;

Figure 2 is a sectional View similar to Fig. l, showing the inner mechanism in elevation;

Fig. 3 is a View, similar to Fig. 2, showing the position of the parts after ejection of the lead;

Figs. 4 and 5 are views in transverse section, taken respectively on the lines 4 4 and 5--5 of Fig. l, and looking in the direction of the arrows;

(Cl. 1Z0-18) Fig. 6 is a view in transverse section, taken on line S-S'of Fig. 3, and looking in the direction of the arrows; v

Fig. '7 is a detail view showing a lead carrier constructed in accordance with the present in- 5 vention; and

Fig. 8 is a detail view showing the ejecting means or plunger which is inserted in the lead carrier.

Referring to the above drawing, a pencil barrel 1n is shown at I, having a restricted portion 2 forming an upper chamber 3, and a lower chamber 4. The barrel tapers toward a point at 5 Aand lies flush withk a spirally slotted tube S which is formed with a tapered end 'I forming a point 15 tube. The tube 6 is preferably formed as a closed slot cut therein forming a spiral slot 8 which terminates at its extremity adjacent the point in a relatively short annular groove 9 which lies in a plane perpendicular to the axis of the pencil, 20 as clearly shown in Figs. 1, 2 and 3. The other extremity of the tube 6 is'threaded and is screwed into therestricted portion 2 of the barrel I. Within the hollow portion of the tube a guide tube I0 is received. This guide tube is formed with a longitudinal slot II with which a bayonet slot I2 communicates at the extremity lying Within the chamber 3. The guide tube terminates in a split and enlarged extremity I3, split to form a plurality of jaws I4 for gripping the lead with uniform pressure. When the guide tube is urged to the rear as viewed in Figs. 1, 2 and 3, the inclined rear face ofthe enlarged portions I3 which is of frusto-conical form cams against the conical seat formed by the tapered extension or point tube 1, thus forcing the jaws I4 against a lead 3" l5.

Within the spirally slotted tube 6 a tubular lead carrier I6 is provided, a radial tooth I1 being formed thereon to engage in the slot 8 between the turns forming the thread of the tube. A plunger I8 is received within the carrier and is formed with a tooth I9 which normally engages in the spiral slot, each tooth extending through the groove II and thus engaging the thread formed by the spirally slotted tube but spaced apart by the pitch thereof. The lead I5 is inserted in the carrier i6 and normally engages the extremity of the plunger I8. When the tooth I9 of the carrier has been advanced into the 50 groove 9 continued advancement of the carrier ceases, while the plunger I8 is moved forward axially of the carrier due to the tooth I9 engaging the remaining portion of the thread 8 as it advances toward the groove 9. This relative move- 55 ment of the plunger ejects the lead I5 from the carrier I6 and adapts the latter to receive a fresh lead.

It is proposed to provide a pencil with an improved form of cap in combination with the lead magazine and to this end the chamber 3 is shown as receiving a lead magazin-e upon which a bead 2l is formed to limit the movementl of the magazine towards the rear of the showing in Fig. 1. The extension of the magazine beyond the bead is adapted to grip an eraser 22 and receive a cap 23 which is advanced over the extension and secured frictionally. The cap 23 is formed with an annular groove 2t internally thereof, a bushing 25 being inserted within the cap in order that it may expand against the inner surface thereof. A peripheral rib 26 is formed on the bushing to engage the groove 213, thus locking the bushing within the cap when it is inserted therein. The outer end of the bushing is preferably flared outwardly at 2l in order that it may seat itself upon the extension of the magazine and engage the bead 2l when the cap is moved toward the barrel to advance the jaws Ill away from the tapered points l. A suitable clip 2S may be mounted upon the cap in any desired fashion.

To transmit rotary motion from the magazine 2G to the guide tube Ill, as well as axial movement thereof with respect to the barrel I, a stub shaft 23 is secured to the end of the magazine. This shaft is formed with a radial tooth 38 and carries a spring 3| which seats against the magazine and a cup-shaped disc 32 which is slidably mounted upon the shaft 29. Tooth 30 limits the movement of the disc 32 and prevents it from moving off of the shaft. In this manner, the tooth 33 may be engaged in the bayonet slot I2 and effectively maintained in` such engagement by means of the spring 3| which seats the tooth in the extremity of the slot I2. To urge the jaws I4 normally in engagement with the lead, the

guide tube IB and magazine 20 are normally urged to the rear, as viewed in Figs. 1 and 2 by means of a spring 33. This spring seats against the disc 32 and forces the foregoing parts to the rear, thus causing thejaws to grip the lead in a well known fashion.

From the foregoing, it will be seen that the guide tube may be moved in either direction without disconnecting the elements thus permitting the lead to be fed or retracted by corresponding movement of the lead carrier IIS. The locking mechanism between the magazine and the guide tube may be readily connected or disconnected, at the same time permitting the pencil to be used freely without accidentally effecting such disconnecting. Such movement thus advances or retracts the lead carrier and causes the ejection of the lead when the carrier has reached the limit of its outward movement. By providing a cap formed with the expanding bushing which is secured in the manner described herein, the elements are quickly and readily assembled and a suitable wearing surface is provided for the cap in order that it may always grip the end of the lead magazine with a suitable friction.

The construction illustrated provides an automatic release of the screw driving connection between the guide tube II! and the spirally slotted tube 6 whenever the elements II and I 9 reach the end of their operative movement and are in the slot 3 as shown in Fig. 3. Any further continuation of the rotary movement in attempting to advance the lead carrier and its associated plunger beyond the position shown in Fig. 3 will simply cause the spirally slotted tube and the guide tube to turn together as a unit. The threads at 2 and 8 are arranged in the same direction so that the bodily rotation of the spirally slotted tube will tend to unscrew it from the barrel and thus shift the tube 6 and contained parts axially to the rear and from the position shown in Fig. 3 and thus away from the barrel. This loosening, if not actual separation, of the tube 6 from the barrel has the effect of putting the pencil out of commission. This releasing of the parts from any holding to resist continued rotation has the effect of preventing rupturing strains from developing between the teeth I'I, I9 and the threads formed by the spiral slot 8.

It is suggested that the cap 23 be rotatable on its bushing 25 with some slight degree of frictional resistance to turning effort. In one physical form of the invention the cap 23 is made of balrelite and the bushing 25 as well as the magazine 20 is made of brass tubing. With this arrangement the frictional engagement between the brass magazine and bushing is greater than the frictional resistance between the bushing and cap. With such construction the lead I5 may be advanced through the clutch jaws I4 as above described and until the projections engage in the slot 9 simply by rotating the cap in the proper feeding direction. Any continued rotary movement of the cap 23 thereafter will simply cause the cap to rotate idly on the bushing 25 as a bearing without effect on the lead feeding screw mechanism and in this way strains are taken off the feeding mechanism during any attempt to further actuate the lead advancing screw mechanism. In this way strain is removed from the projections I'i and I9 on any attempt to continue to rotate the screw feeding mechanism after the projections have reached the end of their lead advancing operative movement. Under such conditions, of course, the screw tube 6 will not unthread itself from the threads at 2. Such unthreading of the tube 6 as a whole will occur only in the event that the rotation is continued by the operator directly engaging the barrel 2i] with the cap removed. A rotation of the cap in the opposite direction will restore the threaded connection between the spirally slotted tube and the barrel and thus permit the normal frictional engagement between the cap and its bushing to act rotatively through the magazine, stub shaft and threaded tube 6 to withdraw the projections Il and I9 from the end of the slot 9 as hereinbefore described.

It will thus be seen that an effective pencil has been provided which performs all operations now required of mechanical pencils, at the same time providing a construction which may be readily taken down and assembled, the lead which is carried thereby being gripped effectively at a plurality of points to prevent breakage thereof due to irregularities in the profile of the lead, and possibility of breakage has been mininn'zed.

While there have been shown, described, and pointed out in the annexed claims, certain novel features of the invention, it will be understood that various omissions, substitutions an-d changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

I claim:

1. A pencil including aybarrel provided with a thread, a rotatable, longitudinally slotted guide tube inserted in the forward end of the barrel with means to limit complete insertion therein, a lead holder axially movable in the tube having follower means projecting through the slot in said guide tube to engage said thread, manually rotatable means inserted into the other end of said barrel, and means to secure the last named means to the tube' to maintain a driving connection therewith to rotate the tube positively7 in either' direction.

2. A pencil according to claim l with means to limit the forward movement of said manually rotatable means.

3. A pencil according to claim l in which the driving connection comprises a bayonet slot in the tube and means on the manually rotatable means to engage the slot.

4. A pencil according to claim l in which the driving connection comprises a bayonet .slot in the tube, a disc slidable on the manually opw erated means, means on the manual means to engage the bayonet slot, and resilient means to urge the disc against the end of the tube.

5. A pencil according to claim l in which the driving connection comprises a bayonet slot in the tube, a cup-shaped disc slidable on the manually operated means, a tooth on the manually operated means to engage the bayonet slot, and a springto urge the disc against the tube.

6. A pencil according to claim l in which the driving connection comprises a stub shaft formed with a tooth, a bayonet slot formed in the guide tube and engaged by the tooth, a cup-shaped disc slidably mounted on the shaft, and a spring normally urging the disc toward the tooth.

7. A pencil including a' barrel provided with internal threads, a spirally slottedtubehaving one end provide-d with external threads threaded into the barrel threads having its other end projecting beyond the barrel and therebetween provided with a spiral slot, a lead holder movable axially of the slotted tube, a plunger in the holder, a guide tube provided with a longitudinally extending slot and terminating at its advance end in jaws forming a lead holding clamp positioned beyond the adjacent end of the slotted tube, and means on the plunger and holder extending through the longitudinal slot and into the spiral slot to move the holder and plunger together axially on relative rotation between the guide tube and barrel thereby to advance the lead through the clamping jaws.

8. A pencil including a barrel, provided with internal threads, a spirally slotted tube having a point-tube at one end slidablymounted in the end of the barrel at the writing end of the pencil and having its other end provided with external threads in screw-threaded engagement with the threads on the barrel, a guide tube extending through and rotatably mounted in the bushing and having an enlarged extremity projecting be# yond the point tube and including jaws for clamping the pencil lead, a spring acting normally on the guide tube to maintain its enlarged extremity in engagement with the point tube its jaws in position clamping the lead, said slotted tube provided with a spiral slot terminating at the writing end of the pencil in an annular groove, a lead carrier slidably mounted in the guide tube, a plunger in the lead carrier, both the carrier and plunger provided with extensions movable on relative rotation between the barrel and guide tube along the spiral slot and into the annular groove and said extensions acting on continued rotation to unscrew' the slotted tube from the barrel against the resistance of the spring and thus minimize any tendency to break of? the extensions from the lead carrier on plunger in their engagement with the slotted tube at the end of their advance along the spiral slot.

9. A pencil including a tube having a closed spiral slot cut therein that terminates at the writing end of the pencil in a relatively short annular groo-ve, a guide tube mounted in said first named tube for rotary movement, projecting beyond the saine at the writing end of the pencil to form va lead engaging clamp and provided with a longitudinally extending slot, a lead holder slidably mounted in the guide tube, a plunger in the lead holder, both the guide tube and the plunger provided With lateral extensions passing through the guide tube slot and engaging in the spiral slot, said lead holder and plunger being fashioned and proportioned relative to the tubes to project the advance end of the plunger beyond the advance end' of the holder and to project the advance end of the holder beyond the clutch forming advance end of the guide tube when the extensions have both advanced to their limits of movement along the spiral slot and into the annular groove.

l0. In a mechanical pencil, the combination of a barrel, a tube secured to the barrel, provided with a spiral slo-t and terminating at one end in a point tube with its bore forming a conical seat at the writing end of the pencil, a guide tube slidable axially and rotatably mounted in the slotted tube and having an enlarged end projecting beyond the same, said enlarged end being split to form a pair of lead clamping jaws, the rear portion of said enlarged end being of frusto-conical form, fitting the seat and reacting therewith normally to hold the jaws in their lead clamping position, said guide tube operable on an axial ad- Vance of the same to shift the enlarged end away from the point tube and thus release the jaws and means within the guide tube and in screw threaded engagement with the slots of the slotted tube to advance the lead through and beyond the jaws and thus expel the lead from the pencil on relative rotation in one direction between the guide tube and slotted tube.

11. In a mechanical pencil, the combination of a barrel, a spirally slotted tube fitted in the barrel and provided with an extension forming a point tube projecting beyond one end of the barrel, a guide tube extending axially through the slotted tube, mounted for rotary movement therein and having one end projecting beyond the point tube and split to form lead gripping jaws close to the Writing end of the lead, a spring within the barrel acting on the guide tube and therethrough acting to telescope the rear ends of the gripping jaws into the point tube to hold the jaws normally in lead gripping position and means in engagementwith the slotted tube for propelling the lead through said jaws and eventually for ejecting the lead from the jaws on relative rotation in one direction between the guide tube and the barrel and for retracting the lead into the barrel on relative rotation in the opposite direction.

l2. In a mechanical pencil, the combination of a barrel, means within and projecting from the barrel at the writing end of the pencil for clamping the pencil lead at an advance point close to the writing end of the lead thereby to minimize any looseness or play between the lead and the pencil, and operable axially of the barrel for releasing the clamping means, a lead carrier mounted in the guide means for axial movement towards and through the clamping means and means including a screw feed connection between the barrel and the lead carrier for advancing and retracting the lead carrier relative to the clamping means and for moving the advance end of the carrier through and beyond the clamping means to eject lead from the pencil.

13. In a. mechanical pencil, the combination of a barrel provided with threads, a spirally slotted tube provided with threads screwed into the barrel threads, lead clamping means at the Writing end of the pencil, resilient means acting on the clamping means and normally tending to hold the same in position clamping the lead and acting normally to secure the slotted tube in its screwed thread engagement with the barrel, a lead carrier mounted for movement toward, from and through the clamping means, a feed screw with one element secured to the lead carrier and the other element formed by the slot in the tube, and said screw feed acting when its elements have reached the limits of their permissible movement in shifting the advance end of the carrier through the clamping means to cause the elements to rotate the slotted tube relative to the barrel ina direction to unscrew the slotted tube from the barrel and thus prevent rupturing strains from developing between the elements of the screw feed.

14. In a mechanical pencil, the combination of a barrel pro-vided with a screw thread, a lead carrier within the barrel, rotatable screw feed means With one of its elements provided with threads normally in engagement with said barrel threads and a coacting element carried by the lead carrier, said elements arranged for shifting the lead carrier to advance the lead out of the barrel, and -means controlled by the advance of the screw feed to its limit of movement in advancing the lead to unscrew the rst named element from the barrel threads on further rotation of the screw feed means thereby to cause both elements of the screw feed to rotate idly together and thus release strains on the elements of the screw feed means after the elements have reached the end of the lead advancing movement of the carrier.

15. In a mechanical pencil, the combination of a barrel provided with a spring stop in the bore, a spirally slotted tube secured to the barrel and provided with a spiral slot, a guide tube extending through the slotted tube and provided at an end with a lead holding clutch projecting beyond the slotted tube, a spring within the barrel bearing at opposite ends on the spring stop and on the guide tube to force the clutch into bearing engagement with the adjacent end of the bushing, said end and clutch reacting to move the clutch into clutching position, means coacting with the slot in the slotted tube for advancing the lead through the clutch and acting on a continuation of rotary movement of the screw means beyond its lead advancing position to shift the guide tube axially against the resistance of said spring and away from the adjacent end of the slotted tube and thus permit an automatic release of the clutch.

16. In a mechanical pencil, the combination of a barrel, means at one end for clutching a pencil lead, spring means acting on the clutching means tending to maintain it in clutching position, manually actuated means shiftable axially of the barrel for releasing the clutching means against the resistance of said spring means, screw feed mechanism including said manually actuated means operable by a rotative movement of said manually actuated means for advancing the lead through and beyond the clutching means to eject the lead from the pencil on rotary movement of the screw feed mechanism in one direction and to restore the advancing means in position to receive a new lead by rotary movement of said mechanism in the reverse direction.

17. In a mechanical pencil, the combination of a barrel, lead controlling mechanism including a member rotatable and slidably mounted in one end of the barrel, a bead on said member for engaging the adjacent end of the barrel to thus limit the movement of the magazine into the barrel, a cap provided with an annular groove, a bushing fitted within the cap and provided with a rib engaging in said groove, said cap and bushing forming a single unit slidable on the outer end of the member and frictionally engaging the same, an end of the bushing being ared outwardly and engaging the bead when the said unit is moved toward the barrel in its act of advancing the member into the barrel.

18. In a mechanical pencil, the combination of a barrel, a screw feed lead advancing mechanism mounted in the barrel with a rotatable and axially shiftable element thereof having one end protruding from the upper end of the barrel and provided beyond the barrel with a bead, a bushing in frictional engagement with the protruding end of said mechanism and limited in its axial movement towards the barrel by said bead, and a cap frictionally coupled to said bushing for rotary movement thereon with means to prevent longitudinal movement relative thereto, whereby rotation of the cap in one direction will cause the mechanism to advance the lead relative to the barrel and said cap being rotatable idly on the bushing when turned in said lead advancing direction after the mechanism has reached the end of its permissible lead advancing movement.

19. In a mechanical pencil, the combination of a barrel, rotative lead controlling mechanism in the barrel, means for limiting the rotative movement in one direction, a cap at the upper end of the barrel and normally in frictional driving relation with said mechanism to actuate the same in said direction on a rotation of the cap, said frictional driving connection between the cap and mechanism permitting the cap to turn idly when the mechanism becomes functionally inoperative.

20. A pencil including a barrel, a restricted internally threaded portion in the barrel forming a chamber, a spirally slotted tube provided with an external thread threaded into the restricted portion, a longitudinally slotted guide tube rotatably supported in said spirally slotted tube, a lead holder movable axially in said guide tube, a plunger in the holder, and means on the plunger and holder extending through the slot in said guide tube and into the slot in said helically slotted tube.

WILLIAM H. BLAKE.

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