EP0276362A1 - Mechanical pencil with an automatically propelled lead - Google Patents
Mechanical pencil with an automatically propelled lead Download PDFInfo
- Publication number
- EP0276362A1 EP0276362A1 EP87112007A EP87112007A EP0276362A1 EP 0276362 A1 EP0276362 A1 EP 0276362A1 EP 87112007 A EP87112007 A EP 87112007A EP 87112007 A EP87112007 A EP 87112007A EP 0276362 A1 EP0276362 A1 EP 0276362A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- body means
- ball cage
- lead
- balls
- lead guide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B43—WRITING OR DRAWING IMPLEMENTS; BUREAU ACCESSORIES
- B43K—IMPLEMENTS FOR WRITING OR DRAWING
- B43K21/00—Propelling pencils
- B43K21/02—Writing-core feeding mechanisms
- B43K21/04—Writing-core feeding mechanisms with the writing-cores brought into position by gravity
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B43—WRITING OR DRAWING IMPLEMENTS; BUREAU ACCESSORIES
- B43K—IMPLEMENTS FOR WRITING OR DRAWING
- B43K21/00—Propelling pencils
- B43K21/02—Writing-core feeding mechanisms
- B43K21/027—Writing-core feeding mechanisms with sliding tubelike writing-core guide
- B43K21/033—Writing-core feeding mechanisms with sliding tubelike writing-core guide with automatic feed by pressure during use of pencil
Definitions
- This invention relates to writing or marking implements in general and, in particular, to a mechanical pencil featuring provisions for automatically propelling the lead, whenever the same is worn to a prescribed degree by writing by the same degree.
- U.S. Patent 4,538,934 represents a typical prior art mechanical pencil with an automatic lead propelling capability.
- This known device comprises a tubular lead guide which has a friction member attached thereto for frictionally engaging the lead and which is sprung with respect to the pencil body toward its writing end, and a one-way locking mechanism for engaging the lead so as to permit its travel toward, and out of, the writing end with comparatively small resistance but to lock the lead against retraction into the body.
- An objection to the noted prior art device is that it automatically expels the lead out whenever its tip is moved off the writing surface, regardless of the extent to which the lead has been worn by that time. Therefore, as the implement is repeatedly moved into and out of contact with the writing surface, the one-way locking mechanism can ruin the cylindrical surface of the lead by repeatedly engaging and disengaging the same and by engaging the same at different points thereon. With its surface so ruined, the lead becomes easy to retract into the body when subjected to writing pressure as the locking mechanism may fail to positively engage the ruined surface of the lead against such retraction.
- the invention as claimed is intended to remedy the foregoing weaknesses of the prior art by providing an improved mechanical pencil capable of automatically propelling the lead just as required.
- the invention provides a mechanical pencil of the type comprising substan tially tubular body means having a writing end, a tubular lead guide which is received in the body means for axial displacement therein and which partly protrudes from the writing end thereof under the bias of a spring, the lead guide receiving a lead therein and being retractable relative to the body means in a direction away from the writing end thereof against the bias of the spring with the wear of the lead, a friction member mounted to the lead guide and engaging the lead so as to normally cause the lead to travel with the lead guide in the axial direction of the body means and to permit the lead to move axially relative to the lead guide when a force in excess of a prescribed degree is exerted on the lead, and chuck means mounted within the body means for gripping the lead against axial displacement relative to the body means in a direction away from the writing end thereof while permitting the lead to slide axially toward the writing end of the body means, characterized by comprising one-way locking means for permitting the lead
- the one-way locking means engages the lead at the same point thereon until the lead wears to a preassigned degree, thereby avoiding the possibility of ruining its surface. Moreover, after the lead has been propelled a unit distance, the one-way locking means can firmly engage an unruined surface part of the lead.
- the mechanical pencil of Figures 1-3 has a substantially tubular body 1 in which a tubular lead guide 2, capable of guiding a lead 3 therethrough, is concentrically mounted for axial sliding motion.
- the body 1 has a front or writing end, shown directed to the left in Figure 1, from which the lead guide 2 partly protrudes outwardly, as has been known heretofore.
- the lead guide 2 carries on its inner end, disposed within the body 1 and shown directed to the right in Figure 1, a friction shoe 4 of rubber or like elastic material for frictionally engaging the lead 3 as the latter extends into the lead guide.
- a substantially tubular socket 5 Coaxially mounted within the rear part, away from the writing end, of the body 1 for axial sliding motion is a substantially tubular socket 5 having an internal taper 5G at or adjacent its forward end.
- the socket 5 is additionally configured to provide an intermediate shoulder 5A facing forwardly of the body 1, a rear shoulder 5B facing rearwardly, and a front shoulder 5D facing forwardly.
- a helical compression spring 6 extends between the intermediate shoulder 5A of the socket 5 and a collar 2A on the lead guide 2.
- the compression spring 6 normally holds the shoulder 2B of the lead guide 2 in abutment against the step 1A of the body 1, and the rear shoulder 5B of the socket 5 in abutment against the front end of a sheath 7 which is screwed into the rear end of the body 1 to form its top part.
- a sleeve 2L integrally and concentrically joined to the lead guide 2 via the shoulder 2B, is formed to include an annular inside surface 2C which tapers toward the rear end of the body 1, and an annular inside ridge 2D located rearwardly of the taper surface 2C.
- the socket 5 is formed to include a tubular forward extension 5E of reduced outside diameter concentrically nested in the sleeve 2L and terminating in a flange 5C.
- a ball cage 8 in the form of a tube with a pair of flanges at both ends is concentrically interposed between sleeve 2L and socket extension 5E for axial sliding motion between the flange 5C of the socket extension 5E and the shoulder 5D of the socket 5.
- the ball cage 8 has a plurality of, three in this embodiment, holes 8A defined therein at constant circumferential spacings. Balls 9 are rotatably received one in each hole 8A.
- the flange 8B at the rear end of the ball cage 8 is engageable with the inside ridge 2D of the sleeve 2L with a force that is greater than the rearward force of the compression spring 10 acting on the ball cage 8 but less than the forward force of the compression spring 6 acting onthe sleeve 2L.
- a chuck 11 Concentrically disposed within the socket 5, a chuck 11 takes the form of a tube loosely surrounding the lead 3. The front end of the chuck 11 is enlarged and split axially to provide a plurality of gripping jaws 11C for frictionally gripping the lead 3.
- the gripping jaws 11C are self-biased outwardly.
- An annular groove or a series of depressions 11A formed in the outer surfaces of the gripping jaws 11C rotatably receive balls 12 which are also held against the internal taper 5G of the socket 5 under pressure from a compression spring 13 acting between a flange 11B on the rear end of the chuck 11 and an inside annular shoulder 5F of the socket 5.
- the force of the spring 13, biasing the chuck 11 rearwardly with respect to the socket 5, is less than that of the spring 6 biasing the lead guide 2 forwardly of the body 1.
- the internal taper 5G of the socket 5 decreases in diameter as it extends rearwardly.
- the gripping jaws 11C are held closed as the balls 12 are captured between the jaws 11c and the socket taper 5G.
- the lead 3 is then positively locked against axial rearward displacement.
- the socket taper 5G increases in diameter as it extends forwardly, the lead 3 is slidable forwardly through the gripping jaws 11c when forced in that direction.
- the gripping jaws 11c will spread apart under their own bias, permitting the free passage of the lead 3 axially therethrough.
- a lead housing mounted within the sheath 7 for accommodating a suitable supply of leads, one of which is shown extending into the lead guide 2, as indicated at 3.
- the lead housing 14 has a tubular forward extension 14C of reduced diameter extending into the socket 5 and terminating in an enlargement 14B in engagement with the annular inside rim 5H of the socket.
- An additional compression spring 15, having a force greater than that of the spring 6, acts between the annular inside shoulder 7A of the sheath 7 and the front end 14A of the lead housing 14. The spring 15 biases the lead housing 14 rearwardly with respect to the sheath 7, so that the front end enlargement 14B of the lead housing extension 14C is normally held against the inside rim 5H of the socket 5.
- a friction band 16 of elastic material is wrapped around the enlargement 14B of the lead housing extension 14C against axial displacement.
- the friction band 16 makes frictional contact with the inside surface of the socket 5.
- Figure 1 depicts the normal state of the mechanical pencil in use, with the lead 3 received in the lead guide 2 and with the tip of the lead disposed substantially flush with the tip of the lead guide. Not only the lead tip but also the lead guide tip is to be held against a desired surface for writing. However, while the lead 3 is locked against retraction by the one-way locking member 11 coacting with the taper socket 5, the lead guide 2 is retractable into the body 1 against the force of the spring 6 even though the balls 9 are caught between taper surface 2C and socket extension 5E. Therefore, with the wear of the lead 3 as a result of writing, the lead guide 2 will gradually retract into the body 1 against the bias of the compression spring 6.
- the balls 9 will allow the lead guide 2 to travel forwardly under the bias of the compression spring 6.
- the ball cage 8 will also travel forwardly with the lead guide 2 as the ridge 2D of the sleeve 2L pushes the rear end flange 8B of the ball cage.
- the lead 3 will travel forwardly with the lead guide by sliding through the gripping jaws 11C of the chuck 11.
- the lead 3 is propelled by the same degree to which it has been worn as above stated.
- the front end of the ball cage 8 subsequently comes into abutment against the flange 5C on the front end of the socket extension 5E, the rear end flange 8B of the ball cage will again ride over the ridge 2D back to the Figure 1 position.
- the ball cage 8 may have several slits extending forwardly from its rear end. Such slits will serve to impart resiliency to the rear end portion of the ball cage 8 as its flange 8B rides back and forth over the ridge 2D of the sleeve 2L.
- Figure 4 shows another slight modification of the Figures 1-3 embodiment, in which the inside ridge 2D on the sleeve 2L and the rear end flange 8B of the ball cage 8 are both absent. There are provided, instead, an annular permanent magnet (or annular row of discrete permanent magnets) 17 disposed just rearwardly of the taper surface 9 on the inside surface of the sleeve 2L, and an annular piece of magnetizable material (or annular row of discrete pieces of magnetizable material) 18 on the rear end of the retainer 8.
- annular permanent magnet or annular row of discrete permanent magnets
- the attractive force of the permanent magnet or magnets 17 exerted on the magnetizable piece or pieces 18 should be greater than the force of the compression spring 10 so that the balls 9 may act to prevent, and permit, the forward displacement of the lead guide 2 as in the Figures 1-3 embodiment.
- the flange 8B on the rear end of the ball cage 8 makes frictional contact with a tubular lining 19 of elastic material disposed just rearwardly of the taper surface 2C and immovably attached to the inside surface of the sleeve 2L.
- the frictional force between flange 8B and elastic lining 19 should be slightly less than the force of the compression spring 10.
- This modified mechanical pencil can be identical in the other details of construction with the first disclosed embodiment.
- the provision of the compression spring 10 is not a requirement. Even in the absence of this spring the balls 9 will perform the desired wedging action if the forward end portion of the ball cage 8 is urged toward the taper surface 2C by virtue of the frictional engagement of its flange 8B with the elastic lining 19. The balls 9 will further move into and out of frictional engagement between taper surface 2C and socket extension 5E with the bidirectional axial displacement of the ball cage 8 relative to the sleeve 2L.
- FIGS 6 a , 6 b , 7 and 8 illustrate another preferred embodiment of the invention.
- parts corresponding to those of the Figures 1-3 embodiment will be identified by the same reference characters for the ease of understanding.
- this alternative embodiment features a thrust member 20 which has a lead passageway 20J defined axially therethrough and which is coaxially disposed behind the chuck 11 within the sheath 7.
- the thrust member 20 is coupled to the sleeve 2L, and thence to the lead guide 2, via connective strips 2F extending rearwardly from the sleeve 2L through clearance holes 5J in the socket 5.
- the thrust member 20 is movable into and out of end-to-end abutment against the chuck 11.
- the thrust member 20 pushes the chuck 11 forwardly against the force of the compression spring 13, only to such an extent that the gripping jaws 11C are slightly open.
- This mechanical pencil also differs from that of Figures 1-3 in that the sheath 7 is itself formed to include a partition 7A forming the bottom of a lead housing 14 accommodating a supply of leads.
- the partition 7A has a funnel-shaped opening 7B in alignment with the lead passageway 20J in the thrust member 20.
- the lead housing 14 has its rear end closed by an eraser 21, which in turn is enveloped by a cap 22 removably fitted over the rear or top end of the sheath 7.
- the present device is to be put to use in the state of Figure 6 a .
- Both lead guide 2 and lead 3 will slightly retract into the body 1 against the bias of the compression spring 6 as the tip of the lead guide is pressed against the writing surface.
- the thrust member 20 Being coupled fast to the lead guide 2, the thrust member 20 will also retract out of abutting contact with the chuck 11, whereupon the latter will also retract under the bias of the compression spring 13, with the consequent gripping of the lead 3 by the gripping jaws 11C.
- Figure 7 represents this state.
- the chuck 11 is now conditioned to firmly lock the lead against further retraction into the body 1 but to permit the lead to be propelled forwardly upon exertion of a relatively small force thereon.
- the lead guide 3 as well as the sleeve 2L and thrust member 20 will gradually retract further into the body 1 with the wear of the lead 3.
- Both ball cage 8 and balls 9 will also retract with the lead guide 3 since these balls do not stick between socket extension 5E and taper surface 2C during such retraction of the lead guide 3.
- the lead guide 2 and the other parts coupled thereto will not travel forwardly of the body 1 despite the forward bias of the spring 6 when the pencil is moved off the writing surface. This is because the balls 9 become wedged in between taper surface 2C and socket extension 5E. Also, since the lead 3 is now engaged by the gripping jaws 11c against retraction, writing can be continued without any such difficulties as have been encountered heretofore.
- the ball cage 8 will come to butt on the shoulder 5D of the socket 5 when the lead 3 is worn to the prescribed degree. Thereupon the ball cage flange 8B will ride forwardly over the ridge 2D on the sleeve 2L, resulting in the disengagement of the balls 9 from between taper surface 2C and socket extension 5E. If now the pencil is moved off the writing surface, the balls 9 will remain disengaged from between taper surface 2C and socket extension 5E because the ball cage flange 8b remains engaged with the front side of the ridge 2D against the force of the spring 10. Consequently, the lead guide 2 as well as the thrust member 20 will travel forwardly of the body 1 under the bias of the spring 6. The lead 3, being frictionally engaged by the shoe 4 on the rear end of the lead guide 2, will also travel with the lead guide without being impeded by the wedging action of the balls 12.
- the thrust member 20 will come into abutment against the chuck 11 and thrust the same forwardly against the force of the spring 13.
- the gripping jaws 11C will then spread apart under their own bias to permit the free passage of the lead 3.
- the ridge 2D on the sleeve 2L will force the ball cage 8 into abutment against the flange 5C on the front end of the socket extension 5E whereupon the ball cage flange 8B will ride back over the ridge 2D.
- the forward travel of the lead guide 3 will come to an end as its shoulder 2B comes to butt on the inside shoulder 1A of the body 1.
- the balls 9 will become re-engaged between taper surface 2C and socket extension 5E as the spring 10 urges the ball cage 8 rearwardly with respect to lead guide 3 and socket 5.
- FIG 9 is shown a further preferred embodiment of the invention which is equivalent to that of Figures 6 a -8 in having the thrust member 20 coupled to the lead guide 3.
- the socket extension 5E is externally tapered at 5K on its front end portion, with the taper surface decreasing in diameter as it extends rearwardly of the socket extension.
- the socket extension 5E also has an annular ridge 5L formed on its outer surface and spaced rearwardly from the taper surface 5K.
- the ball cage 8 Interposed between sleeve 2L and socket extension 5E for rotatably carrying the balls 9 as in all the foregoing embodiments, the ball cage 8 has an inturned rim 8C on its rear end so as to ride back and forth over the ridge 5L on the socket extension 5E.
- the ball cage rim 8C normally lies forwardly of the ridge 5L.
- the rear end of the ball cage 8 is also arranged for movement into and out of abutting engagement with an annular inside rim 2G of the sleeve 2L.
- the compression spring 10 extends between the ball cage rim 8C and the socket shoulder 5A, biasing the ball cage 8 forwardly.
- the balls 9 are caught between the inside surface 2H of the sleeve 2L and the taper surface 5K of the socket extension 5E under the bias of the spring 10.
- the ball cage rim 8c and ridge 5L are capable of locking engagement with each other in opposition to the force of the spring 10 but are to disengage when the ball cage is acted upon by the spring 6 biasing the lead guide 2 forwardly of the body 1.
- the shoulder 2E of the lead guide 3 will push the ball cage 8 rearwardly until the ball cage rim 8C rides over the ridge 5L on the socket extension 5E.
- the ball cage rim 8C will remain in engagement with the rear side of the socket extension ridge 5L when the pencil is subsequently moved off the writing surface, thereby holding the balls 9 disengaged from between sleeve 2L and taper surface 5K.
- the lead guide 2 is free to travel back to the illustrated position with the lead 3 and thrust member 20 under the bias of the spring 6.
- the inside ridge 2G on the sleeve 2L will engage the rear end of the ball cage 8 for pushing the same back to the illustrated position by overriding the ridge 5L on the socket extension 5E.
- Figure 10 shows a slight modification of the Figure 9 embodiment.
- the modification resides in a mouthpiece 23 of conical shape screw-threadedly attached to the front end of the body 1 and defining an axial hole 23A through which the lead guide 2 extends for axial displacement.
- the mouthpiece 23 permits the socket 5 and other parts of the pencil to be inserted in the body 2 through its front end.
- the thrust member 20 used in some of the foregoing embodiments need not be coupled to the lead guide 2 via the connective strips 2F integral with the sleeve 2L. All these parts may be formed in one piece, or divided into discrete units, to conform to design preferences or assemblage conveniences without departing from the scope of the invention.
- a further preferred embodiment of the invention shown in Figures 11 and 12 also has the mouthpiece 23 screwed to the front end of the body 1, with the lead guide 2 extending through its axial hole 23A.
- the lead guide 2 is biased forwardly of the body 1 by the spring 6 disposed the shoulder 5A of the socket 5 and the collar 2A on the sleeve 2L integral with the lead guide.
- the socket 5 has the internal taper 5G adjacent its front end.
- the sleeve 2L has the connective strips 2J extending rearwardly therefrom through clearance holes 5J in the socket 5 and secured to the thrust member 20.
- the chuck 11 Concentrically disposed within the socket 5 is the chuck 11 coacting with its internal taper 5G to firmly grip the lead 3 against rearward displacement but to permit its forward sliding motion, as in all the foregoing embodiments.
- the thrust member 20 is held endwise against the chuck 11, urging the latter forwardly with respect to the socket 5 against the force of the spring 13 so that the gripping jaws 11C are slightly open under their own bias.
- the one-way locking means constituting a feature of the invention is provided between body 1 and thrust member 20 in this embodiment.
- the ball cage 8 rotatably carrying the balls 9 takes the form of a tube having a pair of inturned rims at its opposite ends.
- the ball cage 8 is capable of axial displacement between the rearwardly facing shoulder 1C of the body 1 and the front end of the sheath 7 screwed into the rear end of the body 1.
- the compression spring 10 extends between the shoulder 20B of the thrust member 20 and the front end rim of the ball cage 8 for biasing the ball cage rearwardly with a force less than that of the spring 6. With the ball cage 8 so sprung rearwardly, the balls 9 are normally captured between the inside surface 1D of the body 1 and an external taper 20A formed on the thrust member 20.
- the taper 20A increases in diameter as it extends rearwardly of the thrust member 20.
- the thrust member 20 is further formed to include an annular ridge 20C disposed rearwardly of the taper 20A for engagement with the rear end rim 8C of the ball cage 8.
- the ball cage 8 has several parallel slits extending forwardly from its rear end in order to impart radially inward self-bias to its rear end rim 8C. This self-bias is such that the ball cage rim 8C can positively engage the thrust member ridge 20C in opposition to the force of the spring 10 but will disengage the ridge 20C when the thrust member 20 is forced forwardly by the spring 6.
- the lead guide 2 and thrust member 20 will gradually retract against the force of the spring 6 with the wear of the lead 3 as a result of writing. Such members are not to be sprung back by virtue of the wedging action of the balls 9 if the pencil is moved off the writing surface.
- the ball cage 8 will come to butt on the front end of the sheath 7. Then, with some more wear of the lead 3, the annular ridge 20C on the thrust member 20 will travel rearwardly past the rear end rim 8C of the ball cage 8, and the balls 9 will be dislodged from between body 1 and thrust member taper 20A against the force of the spring 10, as illustrated in Figure 12.
- the rear end rim 8C of the ball cage 8 is capable of positive engagement with the thrust member ridge 20C against the force of the spring 10. Therefore, when the pencil is subsequently moved off the writing surface, the balls 9 will remain dislodged from between body 1 and thrust member taper 20A thereby permitting the lead guide 2 to be propelled forwardly with the lead 3 under the bias of the spring 6.
- the ball cage 8 will then come into abutment against the internal shoulder 1C of the body 1.
- the ball cage rim 8C will then disengage the thrust member rim 20C and ride rearwardly thereover as the thrust member 20 is further forced forwardly to the Figure 1 position by the spring 6.
- the flange portion 5M of the socket 5 is capable of axial displacement between a pair of opposed inside shoulders 1E and 1F of the body 1.
- a helical compression spring 24 mounted between the flange portion 5M of the socket 5 and the shoulder 1F of the body 1. The spring 24 biases the socket 5 forwardly with respect to the body 1 with a force greater than the resultant of the force of the spring 6 and the normal manual pressure to be exerted on the pencil during writing.
- the lead guide 2 of the Figure 13 device can be returned to the illustrated normal position regardless of the extent to which the lead 3 has been worn. To this end a pressure in excess of the normal writing pressure is exerted on the tip of the lead guide 2 thereby retracting the same, as well as the socket 5, ball cage 8 and thrust member 20, further into the body 1 against the forces of the springs 6 and 24 until, with the ball cage rim 8C held against the front end of the sheath 7, the thrust member ridge 20C travels rearwardly past the ball cage rim 8C. Thereupon the balls 9 will become dislodged from between body 1 and thrust member taper 20A thereby permitting the lead guide 2 and other parts to be sprung back to their Figure 13 positions.
- a further embodiment of the invention shown in Figure 14 is also akin to the Figures 11 and 12 embodiment in that the one-way locking means is provided between body 1 and thrust member 20.
- the body 1 is formed to include an annular inside ridge 1G providing a taper surface 1H increasing in diameter as it extends rearwardly, and a smaller annular inside ridge 1J spaced rearwardly from the taper surface 1H.
- Rotatably carrying the balls 9, the tubular ball cage 8 having a pair of flanges on its opposite ends is concentrically mounted between body 1 and thrust member 20 for axial displacement between a pair of opposed shoulders 20D and 20E of the thrust member.
- the spring 10 extends between the front end of the sheath 7 and the rear end flange 8B of the ball cage 8, normally biasing the balls 9 into frictional engagement between the taper surface 1H of the body 1 and the outer surface of the thrust member 20.
- the ball cage 8 may be held in frictional contact with the body 1 as via a lining of elastic material secured to the inside surface of the body.
- the ball cage flange 8B lies forwardly of the body ridge 1J. With the axial displacement of the thrust member 20 relative to the body 1, the ball cage flange 8B will positively engage the body ridge 1J in opposition to the force of the spring 10 but will disengage the same when the thrust member 20 is thrusted forwardly under the force of the spring 6, not shown in Figure 14.
- the other details of construction can be similar to those of the Figurues 11 and 12 embodiment.
- the operation of this Figure 14 mechanical pencil is also believed to be self-evident from the foregoing operational description of the Figures 11 and 12 embodiment.
- FIG. 15 A further preferred embodiment of Figure 15 is analogous with that of Figures 6 a -8 but differs therefrom in that the one-way locking means is provided between the body 1 and the sleeve 2L integral with the lead guide 2.
- the sleeve 2L is formed to include an external annular taper surface 2C, increasing in diameter as it extends axially rearwardly of the sleeve, and an external annular ridge 2D spaced rearwardly from the taper surface.
- the ball cage 8 is concentrically mounted between body 1 and sleeve 2L for axial displacement between the inside shoulder 1K of the body 1 and the front end 5A of the flange portion of the socket 5.
- the spring 10 acts between the collar 2A of the sleeve 2L and the front end rim of the ball cage 8, normally biasing the balls 9 into frictional engagement between the taper surface 2C of the sleeve 2L and the inside surface 1J of the body 1.
- the spring 6 extends between the inside surface 2E of the lead guide shoulder 2B and the front end of the socket 5 for urging the lead guide 2 forwardly with respect to the body 1.
- the rear end rim 8C of the ball cage 8 can positively engage the sleeve rim 2C in opposition to the force of the spring 10 but will disengage the sleeve rim when the lead guide 2 is forced forwardly by the spring 6. It is therefore apparent that the one-way locking means of this embodiment operates as in all the previously disclosed embodiments.
- FIG. 16 A further preferred embodiment of Figure 16 is equivalent to that of Figure 15 in that the one-way locking means is provided between body 1 and sleeve 2L.
- the body 1 has an annular taper surface 1H and annular ridge 1L formed on its inside surface.
- the taper surface 1H increases in diameter as it extends rearwardly of the body 1, and the ridge 1L is spaced forwardly from the taper surface 1H for selective engagement with the front end flange 8A of the ball cage 8.
- the compression spring 10 extends between the rear end flange 8B of the ball cage 8 and the shoulder 5A of the socket 5, normally holding the balls 9 in frictional engagement between the outside surface 2J of the sleeve 2L and the taper surface 1H of the body 1.
- a different type of one-way locking means is provided between body 1 and thrust member 20.
- the thrust member 20 is formed to include a rearward extension 20F of tubular shape having a plurality of parallel slits extending forwardly from its rear end. These slits are intended to permit at least the rear end portion of the thrust member extension 20F to be resiliently constricted as shown in Figure 18.
- Formed on the outside surface of the thrust member extension 20F is an annular ridge 20G which tapers toward the rear end of the thrust member extension and which forms a part of the one-way locking means of this embodiment.
- the taper ridge 20G on the thrust member extension 20F is frictionally held against, or at least partly buried in, the elastic lining 25.
- the thrust member 20 is normally firmly locked against forward displacement with respect to the elastic lining 25 but is relatively free to travel rearwardly in sliding contact therewith.
- An unlocking member 26 is disposed rearwardly of the elastic lining 25 for axial displacement between the rear end of the elastic lining and the inturned rim 7A of the sheath 7.
- the unlocking member 26 has an internal taper 26A which decreases in diameter toward the rear end of the unlocking member.
- the lead guide 2 as well as the sleeve 2L and thrust member 20 will gradually retract from their Figure 17 toward their Figure 18 positions against the force of the spring 6 with the wear of the lead 3.
- the taper ridge 20G on the thrust member extension 20F will travel in sliding contact with the elastic lining 25.
- the taper ridge 20G will become firmly embedded in the elastic lining 25 thereby preventing the lead guide 2 from being sprung back to the Figure 17 position.
- the thrust member extension 20F will have its rear end portion become engaged in the internal taper 26A of the unlocking member 26 when the lead 3 is worn to a predetermined degree. Being slitted longitudinally, the thrust member extension 20F will then be reduced in diameter to such an extent as to result in the disengagement of the taper ridge 20G from the elastic lining 25.
- the thrust member 20 will travel forwardly with the lead guide 2 under the force of the spring 6 upon subsequent movement of this implement out of contact with the marking surface.
- the lead 3 will also travel forwardly in frictional engagement with the friction member 4 on the rear end of the lead guide 2.
- the thrust member 20 Toward the end of its forward stroke the thrust member 20 will butt on the chuck 11 and thrust the same forwardly against the force of the spring 13 thereby opening the gripping jaws 11C of the chuck under their own bias.
- the unlocking member 26, which has been engaged with the thrust member extension 20F, will butt on the elastic lining 25 when the lead guide 2 returns to the Figure 17 position.
- the thrust member extension 20F will then become disengaged from the unlocking member 26, and its slitted rear end portion will expand under its own bias, with the consequent re-engagement of the taper ridge 20G in the elastic lining 25 as in Figure 17.
- the one-way locking means of Figures 17 and 18 is modifiable as shown in Figure 19, in which the inside surface of the body 1 is knurled to provide a series of small annular ridges or beads 1M in subsitution for the elastic lining 25 of Figures 17 and 18.
- the annular beads 1M are of saw-toothed axial section, with the front slope of each tooth being less steep than the rear slope.
- the taper ridge 20G is formed on the slitted rearward extension 20F of the thrust member 20 for engagement with the saw-toothed beads 1M.
- the other details of construction can be identical with those of the Figures 17 and 18 embodiment.
- Figure 20 shows another similar modification of the one-way locking means of Figures 17 and 18.
- the series of saw-toothed annular beads are formed on the slitted rearward extension 20F of the thrust member 20, as indicated at 20H, for engagement with a taper ridge 1N formed on the inside surface of the body 1.
- the taper ridge 1N tapers rearwardly of the body 1.
- the other details of construction can be similar to those of the Figures 17 and 18 embodiment.
- the assembly of lead guide 2, sleeve 2L and thrust member 20 could be of one-piece construction or could be composed of a greater number of discrete units joined together, as in the embodiments of Figures 6 a -16.
- the taper ridge or the set of saw-toothed beads shown formed on the thrust member extension 20F in the Figures 17-20 embodiments could be formed on a rearward extension of the sleeve 2L within the scope of the invention.
- Figures 21 and 22 are illustrations of a further preferred embodiment of the invention, in which a substantially tubular sleeve 30, having a slightly different shape from that of the sleeve 2L of the foregoing embodiments, is rigidly affixed to the lead guide 2 in coaxial relation thereto for axial displacement within the body 1.
- the friction member 4 is mounted fast to this sleeve 30, instead of to the lead guide as in all the preceding embodiments, but its functions are unchanged.
- the one-way locking means of this embodiment includes a taper member 31 in the form of a short tube or ring having an internal taper surface 31A and immovably mounted within the body 1 so as to concentrically surround the sleeve 30.
- the taper surface 31A decreases in diameter as it extends forwardly of the taper member 31A.
- Rotatably carrying the balls 9, the tubular ball cage 8 is concentrically disposed between sleeve 30 and taper member 31.
- the ball cage 8 is axially displaceable relative to the sleeve 30 between a pair of flanges 30A and 30B on its opposite ends, so that these flanges serve as abutments or limit stops for limiting the axial displacement of the ball cage relative to the sleeve.
- a ball cage retarder 32 herein shown as a short tube of hard rubber or like more or less elastic material.
- the ball cage retarder 32 is rigidly mounted within the taper member 31 and has an inturned rim 32A in frictional contact with a rear end portion of the ball cage 8.
- a ball pusher 34 in the form of a flanged tube is loosely fitted over the sleeve 30 and is disposed rearwardly of the balls 9.
- a helical compression spring 35 extends between the ball pusher 34 and the rear end flange 30C of the sleeve 30 for biasing the balls 9 forwardly via the ball pusher. Normally, therefore, the balls 9 are caught between the outer surface 30B of the sleeve 30 and the taper surface 31A of the member 31 under the bias of the spring 35.
- the spring 6 extends between the taper member 31 and the front end flange 30A of the sleeve 30 for biasing the lead guide 2 forwardly of the body 1.
- the noted ball cage retarder 32 can frictionally retain the ball cage 8 against axial displacement in opposition to the forward force of the spring 35 but will yield to permit the ball cage to slide forwardly therepast when the force of the spring 6 acts on the ball cage via the rear end flange 30C of the sleeve 30.
- the lead guide 2 as well as the sleeve 30 attached thereto retracts against the force of the spring 6 with the wear of the lead 3 as a result of marking.
- the lead guide 2 is not to be sprung back if the pencil is moved off the writing surface, because the balls 9 are firmly captured between sleeve surface 30B and taper surface 31A under the force of the spring 35 against such forward displacement of the lead guide 2, and in the face of the possible lateral displacement or oscillations of the sleeve 30.
- the sleeve flange 30A on the retracting lead guide 2 will come into abutment against the ball cage 8 and will move the balls 9 out of engagement between sleeve surface 30B and taper surface 31A in opposition to the resultant of the force of the spring 35 and the frictional force of the friction member 32 in contact with the ball cage. So displaced rearwardly of the taper surface 31A, the balls 9 will permit the lead guide 2 to return to the Figure 21 position under the bias of the spring 6 when the pencil is moved off the writing surface.
- Figure 23 shows only those parts of a modification of the Figures 21 and 22 embodiment which are more or less directly associated with the one-way locking means, it being understood that this Figure 23 embodiment is similar in the other details of construction to that of Figures 21 and 22.
- the sleeve 30 rigidly joined to the lead guide 2 is formed to include an annular ridge 30D on its outer surface.
- the ridge 30D provides a taper surface 30E decreasing in diameter as it extends forwardly of the sleeve 30.
- Concentrically and loosely surrounding the sleeve 30 is the tubular ball cage 8 rotatably carrying the balls 9.
- a tubular ball cage retarder 36 of rubber or like elastic material is rigidly mounted on the sleeve 30 and is disposed just rearwardly of the taper ridge 30D.
- a flange 36A of the ball cage retarder 36 makes frictional contact with the inside surface of the ball cage 8.
- a tubular member 39 Immovably mounted within the body 1 in coaxial relation thereto is a tubular member 39 having an inside surface 39C for contact with the balls 9.
- the tubular member 39 has a pair of inturned rims 39A and 39B on its opposite ends.
- the spring 6 extends between the front end rim 39A of the tubular member 39 and the flange 30A of the sleeve 30 for biasing the lead guide 2 forwardly with respect to the body 1.
- Another helical compression spring 38 acts between the tubular member rim 39A and a tubular ball pusher 37, equivalent to the ball pusher 34 of the Figures 21 and 22 embodiment, for normally urging the balls 9 into engangement between the taper surface 30E of the sleeve 30 and the inside surface 39C of the tubular member 39.
- the one-way locking means of this Figure 23 embodiment is also effective to prevent the lead guide 2 from being sprung back to its initial position during the progress of the wear of the lead 3 to a preassigned degree.
- the ball cage 8 will come into abutment against the rear end flange 39B of the tubular member 39 when the lead 3 is worn to the preassigned degree, with the consequent dislodgement of the balls 9 from between taper ridge 30D and tubular member 39 against the resultant of the force of the spring 38 and the frictional force of the ball cage retarder 36 acting on the ball cage 8.
- the ball cage retarder 36 functions to frictionally retard the re-engagement of the balls 9 between taper ridge 30D and tubular member 39 against the force of the spring 38 as the lead guide 2 starts travelling toward the illustrated normal position under the force of the spring 6.
- the balls 9 will be re-engaged between the two members only after the ball cage 8 has come to butt on the front end rim 39A of the tubular member 39 during the return stroke of the lead guide 2, because then the ball cage retarder 36 will slide over the ball cage 8 under the force of the spring 6.
- Figure 24 shows a slight modification of the Figures 21 and 22 embodiment, in which modification a tubular ball cage retarder 40 of elastic material is firmly sleeved upon the ball cage 8.
- the ball cage retarder 40 has a flange 40A frictionally held against the inside surface 31B of a tubular rearward extension 31C of the taper member 31.
- the other details of construction can be as previously set forth in connection with the Figures 21 and 22 embodiment.
- a tubular ball cage retarder 41 is immovably secured to the inside surface of the body 1, instead of to the taper member extension as in the Figures 21 and 22 embodiment.
- An inturned rim 41A of the ball cage retarder 41 is in frictional engagement with the ball cage 8.
- This embodiment can also be identical in other details of construction with the Figures 21 and 22 embodiment.
- the ball cage retarders 32, 36, 40 and 41 of Figures 21-25 perform the same function of retarding the ball cage 8 so as to assure the complete return of the lead guide to its normal position after the lead has been worn to the prescribed degree. It will also be apparent in connection with the Figures 21 and 25 embodiments that the taper member and the sleeve could be formed integral with the body and the lead guide, respectively.
- Figure 26 illustrates a still further preferred embodiment which represents an adaptation of the one-way locking means of the invention to a mechanical pencil of the type such that when one lead is used up, another is automatically fed into the lead guide.
- the lead guide 2 having the friction member 4 and formed integral with the sleeve 2L is concentrically mounted in the body 1, complete with the mouthpiece 23, for axial displacement.
- the lead guide 2 is biased forwardly of the body 1 by the spring 6 acting between the shoulder 5A of the taper socket 5 and the collar 2A on the sleeve 2L, with the result that the collar 2A is normally held against the inside shoulder 23A of the mouthpiece 23.
- the sleeve 2L is rigidly coupled to the thrust member 20 via connective strips 2B loosely extending through holes 5B in the taper socket 5.
- the chuck 11 Coaxially disposed within the taper socket 5 is the chuck 11 having the gripping jaws 11C with the balls 9 rotatably mounted thereon for rolling engagement with the internal taper of the socket 5.
- the spring 13 acts between the internal shoulder 5C of the taper socket 5 and the shoulder 11A of the chuck 11, biasing the chuck balls 9 toward engagement with the internal taper of the socket.
- the tubular forward extension 44 of the thrust member 20 acts on the gripping jaws 11C at 11B thereby opening the jaws against their own bias.
- the one-way locking means in accordance with the invention is disposed in a rear part of the body 1. It comprises the ball cage 8 with the balls 9, taper member 31, ball cage retarder 32, ball pusher 34 and the spring 35.
- the arrangement of these parts is essentially equivalent to that of the corresponding parts of the Figures 21 and 22 embodiment, except that the one-way locking means of the Figure 26 embodiment is provided between body 1 and the tubular rearward extension of the thrust member 20 whereas the one-way locking means of the Figures 21 and 22 embodiment is provided between the body 1 and the sleeve 30 coupled to the lead guide 2.
- the lead guide 2 When the Figure 26 mechanical pencil, with its various working parts in the depicted state, is first pressed against a desired writing surface, the lead guide 2 will slightly retract into the body 1 against the force of the spring 6. With such retraction of the lead guide 2 the forward extension 44 of the thrust member 20 will disengage the gripping jaws 11C thereby permitting the chuck 11 to be displaced rearwardly under the force of the spring 6. Thus the gripping jaws 11C will close for firmly gripping the lead 3 against rearward displacement as the balls 12 roll over the internal taper of the socket 5. The pencil is to be put to writing with its working parts in this state.
- the one-way locking means functions as in all the foregoing embodiments to assure the gradual retraction of the lead guide 2 with the wear of the lead 3.
Abstract
Description
- This invention relates to writing or marking implements in general and, in particular, to a mechanical pencil featuring provisions for automatically propelling the lead, whenever the same is worn to a prescribed degree by writing by the same degree.
- U.S. Patent 4,538,934 represents a typical prior art mechanical pencil with an automatic lead propelling capability. This known device comprises a tubular lead guide which has a friction member attached thereto for frictionally engaging the lead and which is sprung with respect to the pencil body toward its writing end, and a one-way locking mechanism for engaging the lead so as to permit its travel toward, and out of, the writing end with comparatively small resistance but to lock the lead against retraction into the body.
- An objection to the noted prior art device is that it automatically expels the lead out whenever its tip is moved off the writing surface, regardless of the extent to which the lead has been worn by that time. Therefore, as the implement is repeatedly moved into and out of contact with the writing surface, the one-way locking mechanism can ruin the cylindrical surface of the lead by repeatedly engaging and disengaging the same and by engaging the same at different points thereon. With its surface so ruined, the lead becomes easy to retract into the body when subjected to writing pressure as the locking mechanism may fail to positively engage the ruined surface of the lead against such retraction.
- The invention as claimed is intended to remedy the foregoing weaknesses of the prior art by providing an improved mechanical pencil capable of automatically propelling the lead just as required.
- With this objective in view the invention provides a mechanical pencil of the type comprising substan tially tubular body means having a writing end, a tubular lead guide which is received in the body means for axial displacement therein and which partly protrudes from the writing end thereof under the bias of a spring, the lead guide receiving a lead therein and being retractable relative to the body means in a direction away from the writing end thereof against the bias of the spring with the wear of the lead, a friction member mounted to the lead guide and engaging the lead so as to normally cause the lead to travel with the lead guide in the axial direction of the body means and to permit the lead to move axially relative to the lead guide when a force in excess of a prescribed degree is exerted on the lead, and chuck means mounted within the body means for gripping the lead against axial displacement relative to the body means in a direction away from the writing end thereof while permitting the lead to slide axially toward the writing end of the body means, characterized by comprising one-way locking means for permitting the lead guide to retract into the body means with the wear of the lead during writing and for locking the lead guide against displacement toward the writing end of the body means under the bias of the spring when the mechanical pencil is moved out of contact with a writing surface, and unlocking means for causing the one-way locking means to permit the lead guide, as well as the lead being engaged by the friction member, to travel toward the writing end of the body means under the bias of the spring (6) when the lead is worn to a prescribed degree.
- Among the advantages offered by the above summarized invention is that the one-way locking means engages the lead at the same point thereon until the lead wears to a preassigned degree, thereby avoiding the possibility of ruining its surface. Moreover, after the lead has been propelled a unit distance, the one-way locking means can firmly engage an unruined surface part of the lead.
- Some preferable ways of carrying out the inven tion will now be described in detail with reference to the drawings which illustrate some specific embodiments, in which:-
- Figure 1 is a fragmentary axial section through the mechanical pencil incorporating the novel concepts of the invention, with the tubular lead guide shown extending from the body,
- Figure 2 is a cross section through the mechanical pencil, taken along the line II-II in FIG. 1,
- Figure 3 is a view similar to Figure 1 except that the lead guide is shown retracted into the body,
- Figure 4 is a fragmentary axial section through a slight modification of the mechanical pencil of Figure 1,
- Figure 5 is a fragmentary axial section, partly in elevation, through another slight modification of the Figure 1 mechanical pencil,
- Figure 6a is a fragmentary axial section through another preferred form of the mechanical pencil in accordance with the invention,
- Figure 6b is a fragmentary axial section through that part of the Figure 6a device which is not shown in that figure,
- Figures 7 and 8 are fragmentary sectional views also showing the Figure 6a mechanical pencil but in different states of operation,
- Figure 9 is a fragmentary axial section through still another preferred form of the mechanical pencil in accordance with the invention,
- Figure 10 is a fragmentary axial section through a slight modification of the Figure 9 embodiment,
- Figure 11 is a fragmentary axial section through a further preferred form of the mechanical pencil in accordance with the invention, with the lead guide shown extended from the body,
- Figure 12 is a view somewhat similar to Figure 11 except that the lead guide is shown retracted,
- Figure 13 is a fragmentary axial section through a slight modification of the Figure 11 embodiment,
- Figure 14 is a fragmentary axial section, partly in elevation, through a further preferred form of the mechanical pencil in accordance with the invention,
- Figure 15 is a fragmentary axial section through a further preferred form of the mechanical pencil in accordance with the invention,
- Figure 16 is a fragmentary axial section through a slight modification of the Figure 15 embodiment,
- Figure 17 is a fragmentary axial section through a further preferred form of the mechanical pencil in accordance with the invention, with the lead guide shown extended,
- Figure 18 is a view somewhat similar to Figure 17 except that the lead guide is shown retracted,
- Figure 19 is a fragmentary axial section through a further preferred form of the mechanical pencil in accordance with the invention,
- Figure 20 is a fragmentary axial section through a slight modification of the Figure 19 embodiment,
- Figure 21 is a fragmentary axial section through a further preferred form of the mechanical pencil in accordance with the invention, with the lead guide shown extended,
- Figure 22 is an enlarged, fragmentary, axial section through the Figure 21 mechanical pencil, with the lead guide shown retracted,
- Figure 23 is a fragmentary axial section through a further preferred form of the mechanical pencil in accordance with the invention,
- Figure 24 is a fragmentary axial section through a further preferred form of the mechanical pencil in accordance with the invention,
- Figure 25 is a fragmentary axial section through a further preferred form of the mechanical pencil in ac cordance with the invention, and
- Figure 26 is a fragmentary axial section through a still further preferred form of the mechanical pencil in accordance with the invention.
- The mechanical pencil of Figures 1-3 has a substantially
tubular body 1 in which atubular lead guide 2, capable of guiding alead 3 therethrough, is concentrically mounted for axial sliding motion. Thebody 1 has a front or writing end, shown directed to the left in Figure 1, from which thelead guide 2 partly protrudes outwardly, as has been known heretofore. Thelead guide 2 carries on its inner end, disposed within thebody 1 and shown directed to the right in Figure 1, afriction shoe 4 of rubber or like elastic material for frictionally engaging thelead 3 as the latter extends into the lead guide. - Coaxially mounted within the rear part, away from the writing end, of the
body 1 for axial sliding motion is a substantiallytubular socket 5 having aninternal taper 5G at or adjacent its forward end. Thesocket 5 is additionally configured to provide anintermediate shoulder 5A facing forwardly of thebody 1, arear shoulder 5B facing rearwardly, and afront shoulder 5D facing forwardly. Ahelical compression spring 6 extends between theintermediate shoulder 5A of thesocket 5 and acollar 2A on thelead guide 2. Thecompression spring 6 normally holds theshoulder 2B of thelead guide 2 in abutment against the step 1A of thebody 1, and therear shoulder 5B of thesocket 5 in abutment against the front end of asheath 7 which is screwed into the rear end of thebody 1 to form its top part. - A
sleeve 2L, integrally and concentrically joined to thelead guide 2 via theshoulder 2B, is formed to include anannular inside surface 2C which tapers toward the rear end of thebody 1, and anannular inside ridge 2D located rearwardly of thetaper surface 2C. - As will be seen also from Figure 2, the
socket 5 is formed to include a tubularforward extension 5E of reduced outside diameter concentrically nested in thesleeve 2L and terminating in aflange 5C. Aball cage 8 in the form of a tube with a pair of flanges at both ends is concentrically interposed betweensleeve 2L andsocket extension 5E for axial sliding motion between theflange 5C of thesocket extension 5E and theshoulder 5D of thesocket 5. Theball cage 8 has a plurality of, three in this embodiment,holes 8A defined therein at constant circumferential spacings.Balls 9 are rotatably received one in eachhole 8A. Normally, all these balls are wedged in between thetaper surface 2C of thesleeve 2L and thesocket extension 5E under the pressure of acompression spring 10 acting between thesurface 2E of thelead guide shoulder 2B and the flanged front end of theball cage 8. Theballs 9 form parts of the one-way locking means constituting a feature of the invention. - The
flange 8B at the rear end of theball cage 8 is engageable with theinside ridge 2D of thesleeve 2L with a force that is greater than the rearward force of thecompression spring 10 acting on theball cage 8 but less than the forward force of thecompression spring 6 actingonthe sleeve 2L. - Concentrically disposed within the
socket 5, achuck 11 takes the form of a tube loosely surrounding thelead 3. The front end of thechuck 11 is enlarged and split axially to provide a plurality of gripping jaws 11C for frictionally gripping thelead 3. The gripping jaws 11C are self-biased outwardly. An annular groove or a series of depressions 11A formed in the outer surfaces of the gripping jaws 11C rotatably receiveballs 12 which are also held against theinternal taper 5G of thesocket 5 under pressure from acompression spring 13 acting between a flange 11B on the rear end of thechuck 11 and an insideannular shoulder 5F of thesocket 5. The force of thespring 13, biasing thechuck 11 rearwardly with respect to thesocket 5, is less than that of thespring 6 biasing thelead guide 2 forwardly of thebody 1. Theinternal taper 5G of thesocket 5 decreases in diameter as it extends rearwardly. - Normally, or when the
chuck 11 is fully retracted into thesocket 5 under the force of thecompression spring 13 as shown in Figure 1, the gripping jaws 11C are held closed as theballs 12 are captured between the jaws 11c and thesocket taper 5G. Thelead 3 is then positively locked against axial rearward displacement. However, since thesocket taper 5G increases in diameter as it extends forwardly, thelead 3 is slidable forwardly through the gripping jaws 11c when forced in that direction. Further, when thechuck 11 is itself thrusted forwardly of thesocket 5 against the force of the compression sring 13 in a manner yet to be described, the gripping jaws 11c will spread apart under their own bias, permitting the free passage of thelead 3 axially therethrough. - At 14 in Figures 1 and 3 is seen a lead housing mounted within the
sheath 7 for accommodating a suitable supply of leads, one of which is shown extending into thelead guide 2, as indicated at 3. Thelead housing 14 has a tubularforward extension 14C of reduced diameter extending into thesocket 5 and terminating in anenlargement 14B in engagement with theannular inside rim 5H of the socket. Anadditional compression spring 15, having a force greater than that of thespring 6, acts between the annular insideshoulder 7A of thesheath 7 and thefront end 14A of thelead housing 14. Thespring 15 biases thelead housing 14 rearwardly with respect to thesheath 7, so that thefront end enlargement 14B of thelead housing extension 14C is normally held against theinside rim 5H of thesocket 5. - A
friction band 16 of elastic material is wrapped around theenlargement 14B of thelead housing extension 14C against axial displacement. Thefriction band 16 makes frictional contact with the inside surface of thesocket 5. Thus, upon depression of thelead housing 14 deeper into thesheath 7 against the force of thespring 15 for the delivery of a new lead into thelead guide 2, thesocket 5 will travel forwardly in opposition to the bias of thespring 6 into abutment against the shoulder 1B of thebody 1. - In operation, Figure 1 depicts the normal state of the mechanical pencil in use, with the
lead 3 received in thelead guide 2 and with the tip of the lead disposed substantially flush with the tip of the lead guide. Not only the lead tip but also the lead guide tip is to be held against a desired surface for writing. However, while thelead 3 is locked against retraction by the one-way locking member 11 coacting with thetaper socket 5, thelead guide 2 is retractable into thebody 1 against the force of thespring 6 even though theballs 9 are caught betweentaper surface 2C andsocket extension 5E. Therefore, with the wear of thelead 3 as a result of writing, thelead guide 2 will gradually retract into thebody 1 against the bias of thecompression spring 6. - It is an operational feature of the invention that before fully retracting to the Figure 3 position, the
lead guide 2 is not to travel back to the Figure 1 position in the face of the forward bias of thecompression spring 6 when the mechanical pencil is moved off the writing surface. This is because theballs 9 are wedged under the force of thecompression spring 10 betweensocket extension 5E and taper surface 2C, the latter being formed on thesleeve 2L integral with thelead guide 2. During the lead guide retraction from its Figure 1 position to that of Figure 3, theballs 9 function to permit such retraction but to prevent the forward displacement of the lead guide. - As illustrated in Figure 3, the
rear end flange 8B of theball cage 8 will ride over theinside ridge 2D of thesleeve 2L against the force of thecompression spring 10 immediately following the abutting engagement of the ball cage with theshoulder 5D of thesocket 5. Thereupon theballs 9 will be released from between thesocket extension 5E and thetaper surface 2C. Thelead 3 has now been worn to a predetermined degree. - If now the pencil is moved off the writing surface, the
balls 9 will allow thelead guide 2 to travel forwardly under the bias of thecompression spring 6. Theball cage 8 will also travel forwardly with thelead guide 2 as theridge 2D of thesleeve 2L pushes therear end flange 8B of the ball cage. Further, being caught by thefriction shoe 4 on the rear end of thelead guide 2, thelead 3 will travel forwardly with the lead guide by sliding through the gripping jaws 11C of thechuck 11. Thus thelead 3 is propelled by the same degree to which it has been worn as above stated. As the front end of theball cage 8 subsequently comes into abutment against theflange 5C on the front end of thesocket extension 5E, therear end flange 8B of the ball cage will again ride over theridge 2D back to the Figure 1 position. - When the
lead 3 is used up by the repetition of the foregoing cycle, a new lead must be delivered from thelead housing 14 into thelead guide 2. Toward this end thelead housing 14 is depressed manually into thesheath 7 against the force of thecompression spring 15. The forward thrust of thelead housing 14 will be transmitted via thefriction band 16 to thesocket 5 thereby causing the latter to travel forwardly against the force of thecompression spring 6 until the socket comes to butt on the shoulder 1B of thebody 1. With the continued depression of thelead housing 14, itsforward extension 14C will come into end-to-end abutment against thechuck 11 and will thrust the same forwardly against the force of thecompression spring 13. The jaws 11C at the front end of thischuck 11 will then spread apart under their own bias thereby permitting a new lead to fall from thelead housing 14 into thelead guide 2 under its own weight. - The manual pressure on the
lead housing 14 may now be released. As thelead housing 14 travels back to its normal position under the bias of thecompression spring 15, so will thesocket 5 under the bias of thecompression spring 6. Thechuck 11 will also be sprung back to its normal position with respect to thesocket 5 for gripping the new lead with its jaws 11C. Having thus regained the normal state represented by Figure 1, the mechanical pencil is now ready for writing. - As a possible modification of the Figures 1-3 embodiment, the
ball cage 8 may have several slits extending forwardly from its rear end. Such slits will serve to impart resiliency to the rear end portion of theball cage 8 as itsflange 8B rides back and forth over theridge 2D of thesleeve 2L. - Figure 4 shows another slight modification of the Figures 1-3 embodiment, in which the
inside ridge 2D on thesleeve 2L and therear end flange 8B of theball cage 8 are both absent. There are provided, instead, an annular permanent magnet (or annular row of discrete permanent magnets) 17 disposed just rearwardly of thetaper surface 9 on the inside surface of thesleeve 2L, and an annular piece of magnetizable material (or annular row of discrete pieces of magnetizable material) 18 on the rear end of theretainer 8. The attractive force of the permanent magnet ormagnets 17 exerted on the magnetizable piece orpieces 18 should be greater than the force of thecompression spring 10 so that theballs 9 may act to prevent, and permit, the forward displacement of thelead guide 2 as in the Figures 1-3 embodiment. - In another slight modification of the Figures 1-3 embodiment shown in Figure 5, the
flange 8B on the rear end of theball cage 8 makes frictional contact with atubular lining 19 of elastic material disposed just rearwardly of thetaper surface 2C and immovably attached to the inside surface of thesleeve 2L. The frictional force betweenflange 8B andelastic lining 19 should be slightly less than the force of thecompression spring 10. This modified mechanical pencil can be identical in the other details of construction with the first disclosed embodiment. - In the use of the Figure 5 mechanical pencil the
flange 8B on theball cage 8 will slide forwardly over theelastic lining 19 upon abuttung engagement of the ball cage with theshoulder 5D of thecollet 5, with the consequent disengagement of theballs 9 from between thesocket extension 5E and thetaper surface 2C of thesleeve 2L. As the pencil is subsequently moved off the writing surface, thelead guide 2 will be sprung back to the illustrated normal position before theball cage 8 moves rearwardly with respect to the lead guide under the bias of thecompression spring 10. Being in frictional contact with theelastic lining 19, theretainer 8 will permit theballs 9 to be wedged in betweentaper surface 2C andsocket extension 5E after thelead guide 2 has travelled back to its normal position. - It is to be noted in connection with the Figure 5 embodiment that the provision of the
compression spring 10 is not a requirement. Even in the absence of this spring theballs 9 will perform the desired wedging action if the forward end portion of theball cage 8 is urged toward thetaper surface 2C by virtue of the frictional engagement of itsflange 8B with theelastic lining 19. Theballs 9 will further move into and out of frictional engagement betweentaper surface 2C andsocket extension 5E with the bidirectional axial displacement of theball cage 8 relative to thesleeve 2L. - Figures 6a, 6b, 7 and 8 illustrate another preferred embodiment of the invention. In this embodiment, as well as in all the other embodidments to be presented subsequently, parts corresponding to those of the Figures 1-3 embodiment will be identified by the same reference characters for the ease of understanding.
- With reference to Figure 6a this alternative embodiment features a
thrust member 20 which has alead passageway 20J defined axially therethrough and which is coaxially disposed behind thechuck 11 within thesheath 7. Thethrust member 20 is coupled to thesleeve 2L, and thence to thelead guide 2, viaconnective strips 2F extending rearwardly from thesleeve 2L throughclearance holes 5J in thesocket 5. Thus, with the axial displacement of thelead guide 2 relative to thebody 1, thethrust member 20 is movable into and out of end-to-end abutment against thechuck 11. When thelead guide 2 is in its extreme forward position as in Figure 6a, thethrust member 20 pushes thechuck 11 forwardly against the force of thecompression spring 13, only to such an extent that the gripping jaws 11C are slightly open. - This mechanical pencil also differs from that of Figures 1-3 in that the
sheath 7 is itself formed to include apartition 7A forming the bottom of alead housing 14 accommodating a supply of leads. Thepartition 7A has a funnel-shapedopening 7B in alignment with thelead passageway 20J in thethrust member 20. As seen in Figure 6b, thelead housing 14 has its rear end closed by aneraser 21, which in turn is enveloped by acap 22 removably fitted over the rear or top end of thesheath 7. The other details of construction can be as previously set forth in connection with the Figures 1-3 embodiment. - The present device is to be put to use in the state of Figure 6a. Both
lead guide 2 and lead 3 will slightly retract into thebody 1 against the bias of thecompression spring 6 as the tip of the lead guide is pressed against the writing surface. Being coupled fast to thelead guide 2, thethrust member 20 will also retract out of abutting contact with thechuck 11, whereupon the latter will also retract under the bias of thecompression spring 13, with the consequent gripping of thelead 3 by the gripping jaws 11C. - Figure 7 represents this state. By virtue of the wedging action of the
balls 12 caught between the gripping jaws 11C and theinternal taper 5G of thesocket 5, thechuck 11 is now conditioned to firmly lock the lead against further retraction into thebody 1 but to permit the lead to be propelled forwardly upon exertion of a relatively small force thereon. If the pencil is put to use in this state, thelead guide 3 as well as thesleeve 2L and thrustmember 20 will gradually retract further into thebody 1 with the wear of thelead 3. Bothball cage 8 andballs 9 will also retract with thelead guide 3 since these balls do not stick betweensocket extension 5E and tapersurface 2C during such retraction of thelead guide 3. - Moreover, as in the Figures 1-3 embodiment, the
lead guide 2 and the other parts coupled thereto will not travel forwardly of thebody 1 despite the forward bias of thespring 6 when the pencil is moved off the writing surface. This is because theballs 9 become wedged in betweentaper surface 2C andsocket extension 5E. Also, since thelead 3 is now engaged by the gripping jaws 11c against retraction, writing can be continued without any such difficulties as have been encountered heretofore. - As depicted in Figure 8, the
ball cage 8 will come to butt on theshoulder 5D of thesocket 5 when thelead 3 is worn to the prescribed degree. Thereupon theball cage flange 8B will ride forwardly over theridge 2D on thesleeve 2L, resulting in the disengagement of theballs 9 from betweentaper surface 2C andsocket extension 5E. If now the pencil is moved off the writing surface, theballs 9 will remain disengaged from betweentaper surface 2C andsocket extension 5E because the ball cage flange 8b remains engaged with the front side of theridge 2D against the force of thespring 10. Consequently, thelead guide 2 as well as thethrust member 20 will travel forwardly of thebody 1 under the bias of thespring 6. Thelead 3, being frictionally engaged by theshoe 4 on the rear end of thelead guide 2, will also travel with the lead guide without being impeded by the wedging action of theballs 12. - Sprung forwardly with the
lead guide 2, thethrust member 20 will come into abutment against thechuck 11 and thrust the same forwardly against the force of thespring 13. The gripping jaws 11C will then spread apart under their own bias to permit the free passage of thelead 3. With some more forward travel of thelead guide 2 with thethrust member 20, theridge 2D on thesleeve 2L will force theball cage 8 into abutment against theflange 5C on the front end of thesocket extension 5E whereupon theball cage flange 8B will ride back over theridge 2D. Finally, as illustrated in Figure 6a, the forward travel of thelead guide 3 will come to an end as itsshoulder 2B comes to butt on the inside shoulder 1A of thebody 1. Theballs 9 will become re-engaged betweentaper surface 2C andsocket extension 5E as thespring 10 urges theball cage 8 rearwardly with respect to leadguide 3 andsocket 5. - In Figure 9 is shown a further preferred embodiment of the invention which is equivalent to that of Figures 6a-8 in having the
thrust member 20 coupled to thelead guide 3. In this embodiment, however, thesocket extension 5E is externally tapered at 5K on its front end portion, with the taper surface decreasing in diameter as it extends rearwardly of the socket extension. Thesocket extension 5E also has anannular ridge 5L formed on its outer surface and spaced rearwardly from thetaper surface 5K. - Interposed between
sleeve 2L andsocket extension 5E for rotatably carrying theballs 9 as in all the foregoing embodiments, theball cage 8 has aninturned rim 8C on its rear end so as to ride back and forth over theridge 5L on thesocket extension 5E. The ball cage rim 8C normally lies forwardly of theridge 5L. The rear end of theball cage 8 is also arranged for movement into and out of abutting engagement with an annularinside rim 2G of thesleeve 2L. Thecompression spring 10 extends between the ball cage rim 8C and thesocket shoulder 5A, biasing theball cage 8 forwardly. Normally, therefore, theballs 9 are caught between theinside surface 2H of thesleeve 2L and thetaper surface 5K of thesocket extension 5E under the bias of thespring 10. The ball cage rim 8c andridge 5L are capable of locking engagement with each other in opposition to the force of thespring 10 but are to disengage when the ball cage is acted upon by thespring 6 biasing thelead guide 2 forwardly of thebody 1. - This Figure 9 mechanical pencil is analogous in operation with that of Figures 6a-8, with the
lead guide 2 retreating into thebody 1 with the wear of thelead 3 without being impeded by theballs 9. It will also be seen that theballs 9 function to prevent thelead guide 2 from being sprung forwardly when the pencil is moved off the writing surface during the progress of lead wear. The gripping jaws 11C are held closed under the force of thespring 13 during writing as in all the foregoing embodiments. - When the
lead 3 is worn to the predetermined degree, theshoulder 2E of thelead guide 3 will push theball cage 8 rearwardly until the ball cage rim 8C rides over theridge 5L on thesocket extension 5E. Despite the forward thrust of thespring 10, the ball cage rim 8C will remain in engagement with the rear side of thesocket extension ridge 5L when the pencil is subsequently moved off the writing surface, thereby holding theballs 9 disengaged from betweensleeve 2L andtaper surface 5K. Accordingly, thelead guide 2 is free to travel back to the illustrated position with thelead 3 and thrustmember 20 under the bias of thespring 6. During such return travel of thelead guide 2 theinside ridge 2G on thesleeve 2L will engage the rear end of theball cage 8 for pushing the same back to the illustrated position by overriding theridge 5L on thesocket extension 5E. - Figure 10 shows a slight modification of the Figure 9 embodiment. The modification resides in a
mouthpiece 23 of conical shape screw-threadedly attached to the front end of thebody 1 and defining an axial hole 23A through which thelead guide 2 extends for axial displacement. Being removable from thebody 1, themouthpiece 23 permits thesocket 5 and other parts of the pencil to be inserted in thebody 2 through its front end. - As will be readily understood, the
thrust member 20 used in some of the foregoing embodiments need not be coupled to thelead guide 2 via theconnective strips 2F integral with thesleeve 2L. All these parts may be formed in one piece, or divided into discrete units, to conform to design preferences or assemblage conveniences without departing from the scope of the invention. - A further preferred embodiment of the invention shown in Figures 11 and 12 also has the
mouthpiece 23 screwed to the front end of thebody 1, with thelead guide 2 extending through its axial hole 23A. Thelead guide 2 is biased forwardly of thebody 1 by thespring 6 disposed theshoulder 5A of thesocket 5 and thecollar 2A on thesleeve 2L integral with the lead guide. Thesocket 5 has theinternal taper 5G adjacent its front end. Thesleeve 2L has theconnective strips 2J extending rearwardly therefrom throughclearance holes 5J in thesocket 5 and secured to thethrust member 20. - Concentrically disposed within the
socket 5 is thechuck 11 coacting with itsinternal taper 5G to firmly grip thelead 3 against rearward displacement but to permit its forward sliding motion, as in all the foregoing embodiments. Normally, thethrust member 20 is held endwise against thechuck 11, urging the latter forwardly with respect to thesocket 5 against the force of thespring 13 so that the gripping jaws 11C are slightly open under their own bias. - The one-way locking means constituting a feature of the invention is provided between
body 1 and thrustmember 20 in this embodiment. Concentrically interposed betweenbody 1 and thrustmember 20, theball cage 8 rotatably carrying theballs 9 takes the form of a tube having a pair of inturned rims at its opposite ends. Theball cage 8 is capable of axial displacement between the rearwardly facing shoulder 1C of thebody 1 and the front end of thesheath 7 screwed into the rear end of thebody 1. Thecompression spring 10 extends between the shoulder 20B of thethrust member 20 and the front end rim of theball cage 8 for biasing the ball cage rearwardly with a force less than that of thespring 6. With theball cage 8 so sprung rearwardly, theballs 9 are normally captured between the inside surface 1D of thebody 1 and anexternal taper 20A formed on thethrust member 20. Thetaper 20A increases in diameter as it extends rearwardly of thethrust member 20. - The
thrust member 20 is further formed to include anannular ridge 20C disposed rearwardly of thetaper 20A for engagement with the rear end rim 8C of theball cage 8. Theball cage 8 has several parallel slits extending forwardly from its rear end in order to impart radially inward self-bias to its rear end rim 8C. This self-bias is such that the ball cage rim 8C can positively engage thethrust member ridge 20C in opposition to the force of thespring 10 but will disengage theridge 20C when thethrust member 20 is forced forwardly by thespring 6. - As this mechanical pencil is held against a desired writing surface with its various working parts in the state of Figure 11, the
lead 3 will slightly retract against the force of thespring 6 with thelead guide 2 and thrustmember 20. With the slight retraction of thethrust member 20 thechuck 11 will also retract under the bias of thespring 13, with the consequent engagement of its gripping jaws 11C in thesocket taper 5G. Now thelead 3 is locked against any further retraction but is relatively free to travel forwardly. The pencil is to be put to marking in this state. - The
lead guide 2 and thrustmember 20 will gradually retract against the force of thespring 6 with the wear of thelead 3 as a result of writing. Such members are not to be sprung back by virtue of the wedging action of theballs 9 if the pencil is moved off the writing surface. - As the wear of the
lead 3 proceeds, theball cage 8 will come to butt on the front end of thesheath 7. Then, with some more wear of thelead 3, theannular ridge 20C on thethrust member 20 will travel rearwardly past the rear end rim 8C of theball cage 8, and theballs 9 will be dislodged from betweenbody 1 and thrustmember taper 20A against the force of thespring 10, as illustrated in Figure 12. The rear end rim 8C of theball cage 8 is capable of positive engagement with thethrust member ridge 20C against the force of thespring 10. Therefore, when the pencil is subsequently moved off the writing surface, theballs 9 will remain dislodged from betweenbody 1 and thrustmember taper 20A thereby permitting thelead guide 2 to be propelled forwardly with thelead 3 under the bias of thespring 6. - Travelling forwardly with the
thrust member 20, theball cage 8 will then come into abutment against the internal shoulder 1C of thebody 1. The ball cage rim 8C will then disengage thethrust member rim 20C and ride rearwardly thereover as thethrust member 20 is further forced forwardly to the Figure 1 position by thespring 6. - In a slight modification of the Figures 11 and 12 embodiment shown in Figure 13, the
flange portion 5M of thesocket 5 is capable of axial displacement between a pair of opposed inside shoulders 1E and 1F of thebody 1. There is additionally employed in this mechanical pencil ahelical compression spring 24 mounted between theflange portion 5M of thesocket 5 and the shoulder 1F of thebody 1. Thespring 24 biases thesocket 5 forwardly with respect to thebody 1 with a force greater than the resultant of the force of thespring 6 and the normal manual pressure to be exerted on the pencil during writing. - The
lead guide 2 of the Figure 13 device can be returned to the illustrated normal position regardless of the extent to which thelead 3 has been worn. To this end a pressure in excess of the normal writing pressure is exerted on the tip of thelead guide 2 thereby retracting the same, as well as thesocket 5,ball cage 8 and thrustmember 20, further into thebody 1 against the forces of thesprings sheath 7, thethrust member ridge 20C travels rearwardly past the ball cage rim 8C. Thereupon theballs 9 will become dislodged from betweenbody 1 and thrustmember taper 20A thereby permitting thelead guide 2 and other parts to be sprung back to their Figure 13 positions. - A further embodiment of the invention shown in Figure 14 is also akin to the Figures 11 and 12 embodiment in that the one-way locking means is provided between
body 1 and thrustmember 20. Thebody 1 is formed to include an annular inside ridge 1G providing a taper surface 1H increasing in diameter as it extends rearwardly, and a smaller annular inside ridge 1J spaced rearwardly from the taper surface 1H. Rotatably carrying theballs 9, thetubular ball cage 8 having a pair of flanges on its opposite ends is concentrically mounted betweenbody 1 and thrustmember 20 for axial displacement between a pair ofopposed shoulders 20D and 20E of the thrust member. Thespring 10 extends between the front end of thesheath 7 and therear end flange 8B of theball cage 8, normally biasing theballs 9 into frictional engagement between the taper surface 1H of thebody 1 and the outer surface of thethrust member 20. - As has been set forth in connection with Figure 5, however, the provision of the
spring 10 is not essential. Alternatively, theball cage 8 may be held in frictional contact with thebody 1 as via a lining of elastic material secured to the inside surface of the body. - Normally, the
ball cage flange 8B lies forwardly of the body ridge 1J. With the axial displacement of thethrust member 20 relative to thebody 1, theball cage flange 8B will positively engage the body ridge 1J in opposition to the force of thespring 10 but will disengage the same when thethrust member 20 is thrusted forwardly under the force of thespring 6, not shown in Figure 14. The other details of construction can be similar to those of theFigurues - A further preferred embodiment of Figure 15 is analogous with that of Figures 6a-8 but differs therefrom in that the one-way locking means is provided between the
body 1 and thesleeve 2L integral with thelead guide 2. Thus thesleeve 2L is formed to include an externalannular taper surface 2C, increasing in diameter as it extends axially rearwardly of the sleeve, and an externalannular ridge 2D spaced rearwardly from the taper surface. In the shape of a tube having a pair of inturned rims at its opposite ends, theball cage 8 is concentrically mounted betweenbody 1 andsleeve 2L for axial displacement between the inside shoulder 1K of thebody 1 and thefront end 5A of the flange portion of thesocket 5. Thespring 10 acts between thecollar 2A of thesleeve 2L and the front end rim of theball cage 8, normally biasing theballs 9 into frictional engagement between thetaper surface 2C of thesleeve 2L and the inside surface 1J of thebody 1. Thespring 6 extends between theinside surface 2E of thelead guide shoulder 2B and the front end of thesocket 5 for urging thelead guide 2 forwardly with respect to thebody 1. The other details of construction can be as set forth in connection with the Figures 6a-8 embodiment. - In this Figure 15 embodiment, too, the rear end rim 8C of the
ball cage 8 can positively engage thesleeve rim 2C in opposition to the force of thespring 10 but will disengage the sleeve rim when thelead guide 2 is forced forwardly by thespring 6. It is therefore apparent that the one-way locking means of this embodiment operates as in all the previously disclosed embodiments. - A further preferred embodiment of Figure 16 is equivalent to that of Figure 15 in that the one-way locking means is provided between
body 1 andsleeve 2L. However, in this Figure 16 embodiment, thebody 1 has an annular taper surface 1H and annular ridge 1L formed on its inside surface. The taper surface 1H increases in diameter as it extends rearwardly of thebody 1, and the ridge 1L is spaced forwardly from the taper surface 1H for selective engagement with thefront end flange 8A of theball cage 8. Thecompression spring 10 extends between therear end flange 8B of theball cage 8 and theshoulder 5A of thesocket 5, normally holding theballs 9 in frictional engagement between theoutside surface 2J of thesleeve 2L and the taper surface 1H of thebody 1. The other details of construction are identical with those of the Figure 15 embodiment, and the method of operation is belived to be apparent from the foregoing description. - In a further preferred embodiment of the invention shown in Figures 17 and 18, a different type of one-way locking means is provided between
body 1 and thrustmember 20. Thethrust member 20 is formed to include arearward extension 20F of tubular shape having a plurality of parallel slits extending forwardly from its rear end. These slits are intended to permit at least the rear end portion of thethrust member extension 20F to be resiliently constricted as shown in Figure 18. Formed on the outside surface of thethrust member extension 20F is anannular ridge 20G which tapers toward the rear end of the thrust member extension and which forms a part of the one-way locking means of this embodiment. - Concentrically surrounding at least part of the
thrust member extension 20F is a lining 25 of rubber or like elastic material immovably attached to the inside surface of thebody 1. Normally, as illustrated in Figure 17, thetaper ridge 20G on thethrust member extension 20F is frictionally held against, or at least partly buried in, theelastic lining 25. Thus, by reason of the tapering shape of theridge 20G, thethrust member 20 is normally firmly locked against forward displacement with respect to theelastic lining 25 but is relatively free to travel rearwardly in sliding contact therewith. - An unlocking
member 26 is disposed rearwardly of theelastic lining 25 for axial displacement between the rear end of the elastic lining and theinturned rim 7A of thesheath 7. Generally in the shape of a short tube or ring, the unlockingmember 26 has aninternal taper 26A which decreases in diameter toward the rear end of the unlocking member. - The Figures 17 and 18 mechanical pencil is substantially identical in the other details of construction with that of Figures 6a-8. It will be observed from comparison of Figures 6a and 17 that the one-way locking means of the Figures 17 and 18 has no spring equivalent the
spring 10. - In operation the
lead guide 2 as well as thesleeve 2L and thrustmember 20 will gradually retract from their Figure 17 toward their Figure 18 positions against the force of thespring 6 with the wear of thelead 3. During such retraction of thethrust member 20 thetaper ridge 20G on thethrust member extension 20F will travel in sliding contact with theelastic lining 25. When the pencil is moved off the writing surface, thetaper ridge 20G will become firmly embedded in theelastic lining 25 thereby preventing thelead guide 2 from being sprung back to the Figure 17 position. - As illustrated in Figure 18, the
thrust member extension 20F will have its rear end portion become engaged in theinternal taper 26A of the unlockingmember 26 when thelead 3 is worn to a predetermined degree. Being slitted longitudinally, thethrust member extension 20F will then be reduced in diameter to such an extent as to result in the disengagement of thetaper ridge 20G from theelastic lining 25. Thethrust member 20 will travel forwardly with thelead guide 2 under the force of thespring 6 upon subsequent movement of this implement out of contact with the marking surface. Thelead 3 will also travel forwardly in frictional engagement with thefriction member 4 on the rear end of thelead guide 2. - Toward the end of its forward stroke the
thrust member 20 will butt on thechuck 11 and thrust the same forwardly against the force of thespring 13 thereby opening the gripping jaws 11C of the chuck under their own bias. The unlockingmember 26, which has been engaged with thethrust member extension 20F, will butt on theelastic lining 25 when thelead guide 2 returns to the Figure 17 position. Thethrust member extension 20F will then become disengaged from the unlockingmember 26, and its slitted rear end portion will expand under its own bias, with the consequent re-engagement of thetaper ridge 20G in theelastic lining 25 as in Figure 17. - The one-way locking means of Figures 17 and 18 is modifiable as shown in Figure 19, in which the inside surface of the
body 1 is knurled to provide a series of small annular ridges or beads 1M in subsitution for theelastic lining 25 of Figures 17 and 18. Preferably, and as shown, the annular beads 1M are of saw-toothed axial section, with the front slope of each tooth being less steep than the rear slope. Thetaper ridge 20G is formed on the slittedrearward extension 20F of thethrust member 20 for engagement with the saw-toothed beads 1M. The other details of construction can be identical with those of the Figures 17 and 18 embodiment. - Figure 20 shows another similar modification of the one-way locking means of Figures 17 and 18. In this modification the series of saw-toothed annular beads are formed on the slitted
rearward extension 20F of thethrust member 20, as indicated at 20H, for engagement with a taper ridge 1N formed on the inside surface of thebody 1. The taper ridge 1N tapers rearwardly of thebody 1. The other details of construction can be similar to those of the Figures 17 and 18 embodiment. - In the various embodiments shown in Figures 17-20 the assembly of
lead guide 2,sleeve 2L and thrustmember 20 could be of one-piece construction or could be composed of a greater number of discrete units joined together, as in the embodiments of Figures 6a-16. Also, the taper ridge or the set of saw-toothed beads shown formed on thethrust member extension 20F in the Figures 17-20 embodiments could be formed on a rearward extension of thesleeve 2L within the scope of the invention. - Figures 21 and 22 are illustrations of a further preferred embodiment of the invention, in which a substantially
tubular sleeve 30, having a slightly different shape from that of thesleeve 2L of the foregoing embodiments, is rigidly affixed to thelead guide 2 in coaxial relation thereto for axial displacement within thebody 1. Thefriction member 4 is mounted fast to thissleeve 30, instead of to the lead guide as in all the preceding embodiments, but its functions are unchanged. - The one-way locking means of this embodiment includes a
taper member 31 in the form of a short tube or ring having aninternal taper surface 31A and immovably mounted within thebody 1 so as to concentrically surround thesleeve 30. Thetaper surface 31A decreases in diameter as it extends forwardly of thetaper member 31A. Rotatably carrying theballs 9, thetubular ball cage 8 is concentrically disposed betweensleeve 30 andtaper member 31. Theball cage 8 is axially displaceable relative to thesleeve 30 between a pair offlanges - Additionally incorporated in the one-way locking means of this embodiment is a
ball cage retarder 32 herein shown as a short tube of hard rubber or like more or less elastic material. Theball cage retarder 32 is rigidly mounted within thetaper member 31 and has aninturned rim 32A in frictional contact with a rear end portion of theball cage 8. Aball pusher 34 in the form of a flanged tube is loosely fitted over thesleeve 30 and is disposed rearwardly of theballs 9. Ahelical compression spring 35 extends between theball pusher 34 and therear end flange 30C of thesleeve 30 for biasing theballs 9 forwardly via the ball pusher. Normally, therefore, theballs 9 are caught between theouter surface 30B of thesleeve 30 and thetaper surface 31A of themember 31 under the bias of thespring 35. - The
spring 6 extends between thetaper member 31 and thefront end flange 30A of thesleeve 30 for biasing thelead guide 2 forwardly of thebody 1. The notedball cage retarder 32 can frictionally retain theball cage 8 against axial displacement in opposition to the forward force of thespring 35 but will yield to permit the ball cage to slide forwardly therepast when the force of thespring 6 acts on the ball cage via therear end flange 30C of thesleeve 30. - The Figures 21 and 22 mechanical pencil additionally incorporates, of course, the lead-chucking means comprising the
socket 5, chuck 11 with the gripping jaws 11C,balls 12,spring 13, etc. It will be seen by referring back to Figure 1 that the arrangement of these and other parts of the Figures 21 and 22 embodiment is essentially akin to that of the corresponding parts of the first disclosed embodiment. - In this embodiment, too, the
lead guide 2 as well as thesleeve 30 attached thereto retracts against the force of thespring 6 with the wear of thelead 3 as a result of marking. Thelead guide 2 is not to be sprung back if the pencil is moved off the writing surface, because theballs 9 are firmly captured betweensleeve surface 30B andtaper surface 31A under the force of thespring 35 against such forward displacement of thelead guide 2, and in the face of the possible lateral displacement or oscillations of thesleeve 30. - As pictured in Figure 22, the
sleeve flange 30A on the retractinglead guide 2 will come into abutment against theball cage 8 and will move theballs 9 out of engagement betweensleeve surface 30B andtaper surface 31A in opposition to the resultant of the force of thespring 35 and the frictional force of thefriction member 32 in contact with the ball cage. So displaced rearwardly of thetaper surface 31A, theballs 9 will permit thelead guide 2 to return to the Figure 21 position under the bias of thespring 6 when the pencil is moved off the writing surface. - It is to be appreciated in connection with this embodiment that although the
lead guide 2 is sprung back to the Figure 21 position immediately when the pencil is moved off the writing surface as above stated, theballs 9 do not immediately become re-engaged betweensleeve surface 30B andtaper surface 31A under the force of thespring 35. This is because theball cage retarder 32 acts to retard the forward displacement of theball cage 8 against the force of thespring 35. Immediately before thelead guide 2 returns to the Figure 21 position, therear end flange 30C of thesleeve 30 will come into abutment against the rear end of theball cage 8 and will thrust the ball cage forwardly against the frictional force of theball cage retarder 32. Thus theballs 9 will become captured betweensleeve surface 30B andtaper surface 31A approximately concurrently with the return of thelead guide 2 to the Figure 21 position. - When the
lead 3 is used up by the repetition of the foregoing cycle of operation, a new lead may be supplied from thelead housing 14 into thelead guide 2, as has been explained in connection with the Figures 1-3 embodiment. - Figure 23 shows only those parts of a modification of the Figures 21 and 22 embodiment which are more or less directly associated with the one-way locking means, it being understood that this Figure 23 embodiment is similar in the other details of construction to that of Figures 21 and 22. The
sleeve 30 rigidly joined to thelead guide 2 is formed to include an annular ridge 30D on its outer surface. The ridge 30D provides ataper surface 30E decreasing in diameter as it extends forwardly of thesleeve 30. Concentrically and loosely surrounding thesleeve 30 is thetubular ball cage 8 rotatably carrying theballs 9. A tubularball cage retarder 36 of rubber or like elastic material is rigidly mounted on thesleeve 30 and is disposed just rearwardly of the taper ridge 30D. A flange 36A of theball cage retarder 36 makes frictional contact with the inside surface of theball cage 8. - Immovably mounted within the
body 1 in coaxial relation thereto is atubular member 39 having aninside surface 39C for contact with theballs 9. Thetubular member 39 has a pair ofinturned rims 39A and 39B on its opposite ends. Thespring 6 extends between thefront end rim 39A of thetubular member 39 and theflange 30A of thesleeve 30 for biasing thelead guide 2 forwardly with respect to thebody 1. Anotherhelical compression spring 38, equivalent to thespring 35 of the Figures 21 and 22 embodiment, acts between thetubular member rim 39A and atubular ball pusher 37, equivalent to theball pusher 34 of the Figures 21 and 22 embodiment, for normally urging theballs 9 into engangement between thetaper surface 30E of thesleeve 30 and theinside surface 39C of thetubular member 39. - It will be apparent that the one-way locking means of this Figure 23 embodiment is also effective to prevent the
lead guide 2 from being sprung back to its initial position during the progress of the wear of thelead 3 to a preassigned degree. Theball cage 8 will come into abutment against the rear end flange 39B of thetubular member 39 when thelead 3 is worn to the preassigned degree, with the consequent dislodgement of theballs 9 from between taper ridge 30D andtubular member 39 against the resultant of the force of thespring 38 and the frictional force of theball cage retarder 36 acting on theball cage 8. - As in the preceding embodiment, the
ball cage retarder 36 functions to frictionally retard the re-engagement of theballs 9 between taper ridge 30D andtubular member 39 against the force of thespring 38 as thelead guide 2 starts travelling toward the illustrated normal position under the force of thespring 6. Theballs 9 will be re-engaged between the two members only after theball cage 8 has come to butt on thefront end rim 39A of thetubular member 39 during the return stroke of thelead guide 2, because then theball cage retarder 36 will slide over theball cage 8 under the force of thespring 6. - Figure 24 shows a slight modification of the Figures 21 and 22 embodiment, in which modification a tubular
ball cage retarder 40 of elastic material is firmly sleeved upon theball cage 8. Theball cage retarder 40 has aflange 40A frictionally held against theinside surface 31B of a tubular rearward extension 31C of thetaper member 31. The other details of construction can be as previously set forth in connection with the Figures 21 and 22 embodiment. - In another slight modification of the Figures 21 and 22 embodiment shown in Figure 25, a tubular
ball cage retarder 41 is immovably secured to the inside surface of thebody 1, instead of to the taper member extension as in the Figures 21 and 22 embodiment. An inturned rim 41A of theball cage retarder 41 is in frictional engagement with theball cage 8. This embodiment can also be identical in other details of construction with the Figures 21 and 22 embodiment. - Regardless of the part to which they are affixed, the
ball cage retarders ball cage 8 so as to assure the complete return of the lead guide to its normal position after the lead has been worn to the prescribed degree. It will also be apparent in connection with the Figures 21 and 25 embodiments that the taper member and the sleeve could be formed integral with the body and the lead guide, respectively. - Figure 26 illustrates a still further preferred embodiment which represents an adaptation of the one-way locking means of the invention to a mechanical pencil of the type such that when one lead is used up, another is automatically fed into the lead guide. The
lead guide 2 having thefriction member 4 and formed integral with thesleeve 2L is concentrically mounted in thebody 1, complete with themouthpiece 23, for axial displacement. Thelead guide 2 is biased forwardly of thebody 1 by thespring 6 acting between theshoulder 5A of thetaper socket 5 and thecollar 2A on thesleeve 2L, with the result that thecollar 2A is normally held against the inside shoulder 23A of themouthpiece 23. Thesleeve 2L is rigidly coupled to thethrust member 20 viaconnective strips 2B loosely extending throughholes 5B in thetaper socket 5. - Coaxially disposed within the
taper socket 5 is thechuck 11 having the gripping jaws 11C with theballs 9 rotatably mounted thereon for rolling engagement with the internal taper of thesocket 5. Thespring 13 acts between theinternal shoulder 5C of thetaper socket 5 and the shoulder 11A of thechuck 11, biasing thechuck balls 9 toward engagement with the internal taper of the socket. Normally, however, the tubularforward extension 44 of thethrust member 20 acts on the gripping jaws 11C at 11B thereby opening the jaws against their own bias. - The one-way locking means in accordance with the invention is disposed in a rear part of the
body 1. It comprises theball cage 8 with theballs 9,taper member 31,ball cage retarder 32,ball pusher 34 and thespring 35. The arrangement of these parts is essentially equivalent to that of the corresponding parts of the Figures 21 and 22 embodiment, except that the one-way locking means of the Figure 26 embodiment is provided betweenbody 1 and the tubular rearward extension of thethrust member 20 whereas the one-way locking means of the Figures 21 and 22 embodiment is provided between thebody 1 and thesleeve 30 coupled to thelead guide 2. - When the Figure 26 mechanical pencil, with its various working parts in the depicted state, is first pressed against a desired writing surface, the
lead guide 2 will slightly retract into thebody 1 against the force of thespring 6. With such retraction of thelead guide 2 theforward extension 44 of thethrust member 20 will disengage the gripping jaws 11C thereby permitting thechuck 11 to be displaced rearwardly under the force of thespring 6. Thus the gripping jaws 11C will close for firmly gripping thelead 3 against rearward displacement as theballs 12 roll over the internal taper of thesocket 5. The pencil is to be put to writing with its working parts in this state. The one-way locking means functions as in all the foregoing embodiments to assure the gradual retraction of thelead guide 2 with the wear of thelead 3. - When the
lead 3 is worn to a predetermined de gree, theshoulder 20A of thethrust member 20 will come to butt on the front end of theball cage 8 whereupon theballs 9 will become dislodged from between thethrust member 20 and theinternal taper 31A of thetaper member 31 as in the Figures 21 and 22 embodiment. Consequently, urged by thespring 6, thelead guide 2 will travel back to the illustrated position together with thelead 3 in engagement with thefriction member 4. As has been stated, the gripping jaws 11C are opened by thethrust member extension 44 when thelead guide 2 is in its normal position. If then thelead 3 in use has been so worn that its rear end is located forwardly of the gripping jaws 11C, another lead will fall under its own weight from thelead housing 14 into and through thechuck 11 into end-to-end abutment against the worn lead. This new lead will be automatically used for writing when the old lead is used up.
Claims (41)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT87112007T ATE58872T1 (en) | 1987-01-29 | 1987-08-19 | MECHANICAL PEN WITH AUTOMATIC REFILL. |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17363/87 | 1987-01-29 | ||
JP62017363A JP2519913B2 (en) | 1987-01-29 | 1987-01-29 | Self-feeding type pencil |
JP3155787U JPH051424Y2 (en) | 1987-03-04 | 1987-03-04 | |
JP31557/87U | 1987-03-04 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0276362A1 true EP0276362A1 (en) | 1988-08-03 |
EP0276362B1 EP0276362B1 (en) | 1990-12-05 |
Family
ID=26353866
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP87112007A Expired - Lifetime EP0276362B1 (en) | 1987-01-29 | 1987-08-19 | Mechanical pencil with an automatically propelled lead |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0276362B1 (en) |
KR (1) | KR900003504B1 (en) |
DE (1) | DE3766612D1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1018441A1 (en) * | 1999-01-08 | 2000-07-12 | Micro Co., Ltd. | Autommatic mechanical pencil |
EP2347997A2 (en) | 1999-08-20 | 2011-07-27 | Basf Se | Method for producing a crystalline, zeolithic solid |
CN103192625A (en) * | 2013-04-13 | 2013-07-10 | 温州市新亚文具有限公司 | Automatic refill projection device for pen |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3229497A1 (en) * | 1982-08-07 | 1984-02-09 | Fa. J.S. Staedtler, 8500 Nürnberg | Pencil with lead advance, and its use |
DE3515219A1 (en) * | 1984-04-27 | 1985-10-31 | Pentel K.K., Tokio/Tokyo | MECHANICAL WRITING PEN |
-
1987
- 1987-08-19 EP EP87112007A patent/EP0276362B1/en not_active Expired - Lifetime
- 1987-08-19 DE DE8787112007T patent/DE3766612D1/en not_active Expired - Lifetime
- 1987-09-15 KR KR1019870010200A patent/KR900003504B1/en not_active IP Right Cessation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3229497A1 (en) * | 1982-08-07 | 1984-02-09 | Fa. J.S. Staedtler, 8500 Nürnberg | Pencil with lead advance, and its use |
DE3515219A1 (en) * | 1984-04-27 | 1985-10-31 | Pentel K.K., Tokio/Tokyo | MECHANICAL WRITING PEN |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1018441A1 (en) * | 1999-01-08 | 2000-07-12 | Micro Co., Ltd. | Autommatic mechanical pencil |
EP2347997A2 (en) | 1999-08-20 | 2011-07-27 | Basf Se | Method for producing a crystalline, zeolithic solid |
CN103192625A (en) * | 2013-04-13 | 2013-07-10 | 温州市新亚文具有限公司 | Automatic refill projection device for pen |
CN103192625B (en) * | 2013-04-13 | 2015-11-11 | 温州市新亚文具有限公司 | The automatic propelling device of pen |
Also Published As
Publication number | Publication date |
---|---|
KR880008892A (en) | 1988-09-13 |
DE3766612D1 (en) | 1991-01-17 |
EP0276362B1 (en) | 1990-12-05 |
KR900003504B1 (en) | 1990-05-21 |
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