Patent Publication Number: US-6210058-B1

Title: Side knock type mechanical pencil

Description:
This application is a divisional application of U.S. Ser. No. 09/065,520 filed Apr. 24, 1998, now U.S. Pat. No. 6,099,182, which is a continuation of U.S. Ser. No. 08/770,300, filed Dec. 20, 1996, now U.S. Pat. No. 5,791,797, which is a continuation of of U.S. Ser. No. 08/327,549, filed Oct. 24, 1994, now abandoned, the entire contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a side knock type mechanical pencil, particularly a side knock type mechanical pencil provided with a mechanism for the delivery of a rod-like article such as an eraser or the like. 
     2. Description of the Prior Art 
     Heretofore, various side knock type mechanical pencils have been proposed such as, for example, the one disclosed in U.S. Pat. No. 3,883,253 and illustrated in FIG. 1 attached hereto. According to this prior art example, a knock lever  22  is mounted within a side hole  21  of a cylindrical shell  20  having a chuck mechanism, and a lead is pushed out by knocking the knock lever  22  with a finger tip of the use while grasping the vicinity of the knock lever. More particularly, upon operation of the knock lever  22 , an actuating portion  22   a  thereof comes into abutment with a slant portion  24   a  of a slider  24  provided in an inner tube set  23 , thereby causing the inner tube set  23  to move forward along the inner wall surface of the cylindrical cell  20  against a backward biasing force of a spring  25 , whereby a chuck  26  is opened to effect delivery of a lead. 
     In such convention mechanical pencil, however, a side knock mechanism is generally positioned in the grip portion. Therefore, in the case where a grip member formed of an elastic material such as rubber is formed in that portion, the diameter of the grip portion becomes large, so the diameter of a lead tank  27  is set to a size which permits one lead to pass therethrough, and a space for spare leads is formed in the rear portion. Recently, however, there has been proposed a mechanical pencil having in the rear portion thereof a mechanism for the delivery of a rod-like article such as an eraser or the like. In a side knock type mechanical pencil having such a mechanism incorporated therein, there is no space for spare leads in the rear portion thereof; besides, the diameter of the lead tank  27  is required to be made small, and thus it has been difficult to accommodate spare leads. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a side knock type mechanical pencil having a sufficient space in the rear portion thereof and capable of enlarging the inside diameter of a lead tank and that of a side member, which are limited in length, so as to permit a plurality of spare leads to be received therein and also capable of providing a grip member if necessary. 
     It is another object of the present invention to provide a side knock type mechanical pencil having a rear-end knock mechanism in addition to a side knock function in order to permit a lead to be pushed out easily in the initial continuous knocking though this is difficult in the side knock operation. 
     It is a further object of the present invention to provide a side knock type mechanical pencil wherein a slide member as a constituent of a side knock mechanism is formed as a one-piece member to reduce the number of components and cost and facilitate the assembling work. 
     According to the present invention, in order to achieve the above-mentioned objects, there is provided a side knock type mechanical pencil including a cylindrical shell having a ferrule; a lead tank disposed axially slidably within the cylindrical shell; a chuck disposed at a front end portion of the lead tank, with a chuck ring being loosely fitted on the chuck; a resilient member for urging the chuck backward; and a slide knock mechanism provided in the cylindrical shell, the slide knock mechanism comprising a slide knock member provided in the cylindrical shell and a slide member having a lead inserting through hole formed axially and also having a slant portion for abutment with the side knock member, the slide member being movable axially against the backward biasing force of the resilient member. 
     Further, according to the present invention, in order to achieve the above-mentioned objects, there is provided a side knock type mechanical pencil including a cylindrical shell having a ferrule; a slide member disposed axially slidably within the cylindrical shell; a chuck disposed at a front end portion of the slide member, with a chuck ring being loosely fitted on the chuck; a resilient member for urging the chuck backward; and a side knock mechanism provided in the cylindrical shell, the side knock mechanism comprising a side knock member provided in the cylindrical shell and the slide member, the slide member being movable axially against the backward biasing force of the resilient member and having a slant portion for abutment with the side knock member and also having a lead inserting through hole formed axially. 
     By depressing a knock lever as the side knock member, the slide member is moved forward against the backward bias of the resilient member through the slant portion as a knock surface of the slide member to open the chuck and push out a lead. Where required, a rod-like article such as an eraser or the like can be pushed out backward by rotating a rear cap. Further, when continuous knocking is required, the rear end of the mechanical pencil can be knocked, whereby a lead can be pushed out. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a conventional side knock type mechanical pencil; 
     FIG. 2 is a longitudinal sectional view of a side knock type mechanical pencil according to embodiment 1 of the present invention; 
     FIG. 3 is a side view of a slide member illustrated in FIG. 2; 
     FIG. 4 is a sectional view of the slide member illustrated in FIG. 3; 
     FIG. 5 is a bottom view of the slide member illustrated in FIG. 4; 
     FIG. 6 is a sectional view taken along line A—A in FIG. 2; 
     FIG. 7 is a perspective view of a guide cylinder illustrated in FIG. 2, with both eraser and eraser support member inserted therein; 
     FIG. 8 is a perspective view of only the guide cylinder illustrated in FIG. 7; 
     FIG. 9 is a longitudinal sectional view of the guide cylinder illustrated in FIG. 8; 
     FIG. 10 is a perspective view of an eraser support member illustrated in FIG. 2; 
     FIG. 11 is a side view of a slider illustrated in FIG. 10; 
     FIG. 12 is a longitudinal sectional view of the slider illustrated in FIG. 10; 
     FIGS.  13 (A) and  13 (B) are longitudinal sectional views of a principal portion, showing a side knock operation in embodiment 1; 
     FIGS.  14 (A) and  14 (B) are longitudinal sectional views of a principal portion, showing an eraser delivery operation in embodiment 1; 
     FIG. 15 is a longitudinal sectional view of a side knock type mechanical pencil according to embodiment 2 of the present invention; 
     FIG. 16 is a side view of a slide member illustrated in FIG. 15; 
     FIG. 17 is a longitudinal sectional view of a side knock type mechanical pencil according to embodiment 3 of the present invention; 
     FIG. 18 is a longitudinal sectional view of a side knock type mechanical pencil according to embodiment 4 of the present invention; and 
     FIG. 19 is a longitudinal sectional view of a side knock type mechanical pencil according to embodiment 5 of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
     Embodiment 1 
     FIGS. 2 to  14  illustrate a mechanical pencil according to embodiment 1 of the present invention, in which knocking operation is performed by side knock and rear-end knock. In those figures, a writing mechanism is provided in the front portion of the interior of a cylindrical shell  1 , while in the rear portion thereof is provided an eraser delivery mechanism. 
     Reference will first be made to the front writing mechanism. Within the cylindrical shell  1  is disposed a lead tank  2  axially slidably, the lead tank  2  having an inside diameter sufficient to receive therein a plurality of leads together. A chuck  3  is press-fitted and fixed into the front end of the lead tank  2 , with a chuck ring  4  being loosely fitted on the chuck  3 . Further, a sleeve  5  is provided outside the chuck  3 , and inside the sleeve  5  is mounted a chuck spring  6  for urging the lead tank  2  backward. 
     A ferrule  7  having on the inner periphery side thereof a stepped portion  7   a  which serves as a stopper for the chuck ring  4  is threadedly engaged with the front end of the cylindrical shell  1 , and within the ferrule  7  are disposed an axially slidable tip pipe  8  and a slider  9  into which is press-fitted and fixed the rear end of the tip pipe  8  and whose inner peripheral portion supports a lead by virtue of a predetermined frictional resistance. Further, a cushion spring  10  for absorbing an excessive writing pressure is mounted between the rear end of the sleeve  5  and the cylindrical shell  1 . 
     The reference numeral  10   a  denotes a return spring mounted between the cylindrical shell  1  and the front end of a slide member  17  which will be described later. The return spring  10   a,  which has a biasing force weaker than that of the chuck spring  6  and urges the slider  17 , etc. backward, is advantageous in the following point. If the rear end of the lead tank  2  is in abutment with a stepped portion of the front inner periphery of the slide member  17 , there is created a knocking state and the chucking portion at the front end of the chuck  3  is open slightly, thus causing lead slip. Therefore, even if there are variations in the overall length of the lead tank  2 , it is necessary in design to keep the rear end of the lead tank  2  slightly spaced from the stepped portion of the front inner periphery of the slide member  17  in order to avoid mutual abutment. In the presence of such a gap, however, it is likely that the slide member  17  will move back and forth by the distance corresponding to the gap. However, since the return spring  10   a  urges the slide member  17  continually backward, there is no fear of such longitudinal slide (wobbling) of the slide member  17 . 
     Description is now directed to the eraser delivery mechanism located at the rear portion of the mechanical pencil. A guide cylinder  11  shown in FIGS. 7 to  9  is extractably fitted in a receptacle portion  17   a  of a larger diameter, the receptacle portion  17   a  being formed at the rear portion of the slide member  17  which is shown in FIG.  4 . More specifically, an annular groove  17   b  is formed in the inner periphery of the receptacle portion  17   a,  while on the outer periphery of the guide cylinder  11  is formed a ring-like protuberance  11   a  for engagement with the annular groove  17   b.    
     The guide cylinder  11  has a pair of slits  11   b  formed axially and opposedly to each other. The slits  11   b  are closed at their rear ends, at which there is formed a large-diameter portion  11   c.  The guide cylinder  11  is inserted axially slidably into a rotatably connected rear cap  12  and is engaged circumferentially with the rear cap, with its rear end side projecting from the rear end of the cap  12 . 
     At the front portion of the guide cylinder  11  are integrally formed a pair of elastic retaining lugs lid for engagement with the rear cap  12  to provide an axial lock. When inserted into the rear cap  12 , the elastic retaining lugs lid bend inwards and then revert to the original state as they pass through the rear cap. Thereafter, the guide cylinder  11  and the rear cap  12  are rotatable but are locked axially, so are prevented from falling off. 
     Further, an eraser support member  14  which supports an eraser  13  is inserted axially slidably into the guide cylinder  11  and is engaged circumferentially with the guide cylinder. As shown in FIGS. 10 to  12 , the eraser support member  14  is provided with a cylindrical body  14   a,  a pair of opposed arm portions  14   b  extending backward from the cylindrical body  14   a,  and a pair of inclined lugs  14   c  formed on the outer walls of the arm portions  14   b.  The inclined lugs  14   c  extend the slits  11   b  formed axially in the guide cylinder  11  and come into engagement with a spiral groove  12   a  formed in the inner periphery of the rear cap  12 . 
     As shown in FIG. 2, a grip member  15 , e.g. rubber, is attached to the grip portion of the cylindrical shell  1 . Behind the grip member  15 , a knock lever  16  for side knock is mounted in a side wall portion of the cylindrical shell  1  so that it can be pushed axially. Inside corners of the front end of the knock lever  16  are in abutment with a slant face  17   c  of the slide member  17 . More specifically, the slide member  17  has such a structure as shown in FIGS. 3 and 4. As illustrated therein, the slide member  17  is internally formed with a through hole  17   d  capable of receiving therein two or more leads at a time each 0.5 mm in diameter for example. The slide member  17  is formed with a large-diameter portion having the slant face  17   c  in a position opposed to the knock lever  16  when set in the mechanical pencil. 
     The slant face  17   c  is formed downward from the front toward the rear. When the knock lever  16  is depressed and comes into abutment with the slant face  17   c,  the slide member  17  is moved forward. In side faces of the slide member  17  are axially formed engaging grooves  17   e  for positioning, while in side faces of the receptacle portion  17   a  located at the rear there are formed engaging grooves  17   f  for swivel stop which come into engagement with ribs  1   a  (FIG. 6) formed on the inner periphery of the cylindrical shell  1 . As shown in FIG. 4, on the inner periphery of the rear receptacle portion  17   a  is formed a polygonal portion  17   g  which is, for example, octagonal in cross section and which comes into engagement with a polygonal portion  11   d  of the guide cylinder  11  to fulfill a swivel stop function. 
     Thus, according to this embodiment 1 there is given a technical consideration such that by connecting the writing mechanism located at the front and the eraser delivery mechanism located at the rear with each other it is made possible to effect not only side knock operation but also rear-end knock operation. In more particular terms, a rotating operation is required for pushing out the eraser  13  in the eraser delivery mechanism located at the rear. In this connection, if the rotation at the rear is transmitted to the front writing mechanism, it is impossible to effect the rotating operation due to idle running. To prevent such idle running, as mentioned above, the inside of the slide member  17  and that of the guide cylinder  11  are formed in a polygonal shape, e.g. octagonal shape, so as to permit sliding motion only in the axial direction. 
     According to embodiment 1, since rear-end knock is also possible, a lead can be easily pushed out little by little by side knock operation during writing. However, in order to start writing while a lead is still within the lead tank  2  and has not reached the tip pipe  8  yet, it is necessary to repeat knocking continuously for pushing out the retracted tip pipe  8  and lead. But the side knock operation is usually performed with the cylindrical shell  1  laid on its side, so the lead is difficult to come out even after release of the chuck  3 . In this case, rear-end knock operation is most suitable which is performed in an upright state of the cylindrical shell  1 . Besides, in the case of repeating knock continuously, rear-end knock is easier and superior in operability than side knock. 
     The operation of embodiment 1 constructed as above will now be described in detail with reference to FIG.  13 . FIG.  13 (A) shows a state before knock. In this state, when the side knock lever  16  is depressed for writing as shown in FIG.  14 (B), inner corner portions of the front end of the knock lever  16  slide from above to below along the slant face  17   c  of the slide member  17 , thereby pushing the slide member forward. As a result, the lead tank  2  and the chuck  3  are moved forward against the backward bias of the chuck spring  6 . In the course of this forward movement, the chuck ring  4  loosely fitted on the chuck  3  comes into abutment with the stepped portion  7   a  of the inner periphery of the ferrule  7  and is disengaged thereby, while the slider  9  is moved forward by the chuck  3  and hence the tip pipe  8  is projected. 
     Upon release of the knock, the slide member  17  is returned backward by virtue of the chuck spring  6 . Further, by repeating this knocking operation, the lead is pushed out to permit writing. After writing, by pushing the pencil tip lightly against the paper surface or pushing it lightly with a finger tip and subsequent knocking the knock lever  16 , the chuck  3  is released and the lead and the tip pipe  8  are received into the ferrule  7 . 
     The rear-end knock operation in this embodiment will now be described. When the rear end of the mechanical pencil is knocked with the pencil perpendicular to the paper surface, the eraser delivery mechanism is moved forward through the cylindrical shell  1  against the backward bias of the chuck spring  6 . As a result, the components connected to this mechanism such as the slide member  17 , lead tank  2  and chuck  3  are advanced, whereby a lead is pushed out in the same manner as in the foregoing side knock operation. 
     For pushing out the eraser in such a state as shown in FIG.  14 (A), the rear cap  12  is rotated while the cylindrical shell  1  of the mechanical pencil body is fixed, with the result that the eraser support  14  rises through the guide cylinder  11 . This is because the inclined lugs  14   c  of the eraser support member  14  are in engagement with the slits  11   b  of the guide cylinder  11 . However, the guide cylinder  11  is swivel-stopped in combination with the slide member  17 , which in turn is swivel-stopped in combination with the cylindrical shell  1 . Therefore, as the inclined lugs  14   c  of the eraser support member  14  move axially upward through the slits  11   b  of the guide cylinder  11  along the spiral groove  12   a  formed in the inner periphery of the rear cap  12 , with rotation of the rear cap, the eraser support member  14  comes to assume the state shown in FIG.  14 (B). 
     In the case where a lead is to be newly fed, all the components of the eraser delivery mechanism positioned above the guide cylinder  11 , except the slide member  17 , can be removed as an independent unit by grasping and pulling out the rear cap  12 . Thus, a plurality of leads can be fed at a time to the lead tank  2  from the receptacle portion  17   a  of the slide member  17 . 
     Embodiment 2 
     Referring now to FIGS. 15 and 16, there is illustrated embodiment 2 of the present invention. In this embodiment, a tip pipe  8  and a lead can be pushed out by only side knock operation. According to this embodiment 2, since a slide member  17  and an eraser delivery mechanism located at the rear are structurally separated from each other, a writing mechanism located at the front and the eraser delivery mechanism located at the rear are completely independent of each other in point of function. 
     More specifically, a short guide portion  17   h  as guide means for the replenishment of new leads is integrally formed at the rear end of the slide member  17 . Spacedly from the guide portion  17   h , a stationary cylinder  18  is press-fitted and fixed strongly into a cylindrical shell  1 . In more particular terms, on the outer periphery of the stationary cylinder  18  is formed an annular projection  18   a  having an upright portion at the rear end and also having a slant portion which declines gradually toward the front, when viewed in section. Therefore, when the stationary cylinder  18  is press-fitted into the cylindrical shell  1  strongly from the rear end, using a jig, the annular projection  18   a  collapses and the stationary cylinder  18  is completely fixed within the cylindrical shell. 
     A guide cylinder  11  is extractably engaged in the stationary cylinder  18 , and the upper end of the cylinder  18  has a slant face  18   b  which is formed in the shape of a funnel so as to facilitate axial insertion of a lead. The other points of the eraser delivery mechanism are the same as in the previous embodiment 1. For the replenishment of leads, according to this embodiment 2, by pulling out the eraser delivery mechanism while grasping the large-diameter portion  11   c  or the rear cap  12  which are exposed at the rear of the guide cylinder  11 , the whole of the unitized mechanism can be removed from the cylindrical shell  1  except the stationary cylinder  18  and hence it is possible to replenish leads easily. 
     In this embodiment 2, since the mechanical pencil mechanism located at the front and the eraser delivery mechanism located at the rear are completely independent of each other in point of function, it is not necessary to give such a technical consideration as that for preventing the rotating motion at the rear from being transmitted to the front. Further, since not only both mechanisms are completely independent of each other but also the mechanical pencil mechanism is securely held by the stationary cylinder  18  which is fixed strongly in the cylindrical shell  1 , there is no fear of occurrence of such inconveniences as an erasing pressure being transmitted to the mechanical pencil mechanism, causing a lead to be pushed out unnecessarily, and slight retraction of the eraser. 
     Further, if the slide member  17  used in embodiment 2 is formed with engaging grooves  17   e  and  17   f  as shown in FIG. 16, and if engaging ribs  1   a  (FIG. 6) are formed in the inner periphery of the cylindrical shell  1  correspondingly to those grooves, the slide member  17  and the cylindrical shell  1  are mutually prevented from rotation. This is convenient. The slide member  17  has a backwardly descending slant face  17   c  in a position in which the slant face  17   c  come into opposition to a side knock member  16  provided in the cylindrical shell  1  when the slide member is mounted into the cylindrical shell. In assembling, therefore, by inserting the slide member  17  into the cylindrical shell  1  while conforming its engaging grooves  17   e  and  17   f  to the engaging ribs  1   a  of the cylindrical shell, the slide member can be set with high directionality. One of the engaging grooves  17   e  and  17   f  may be omitted if only the rotation preventing or positioning function can be attained. Further, even if engaging lugs are formed on the slide member  17  side in place of the engaging grooves  17   e  and  17   f  of the slide member and engaging grooves are formed in the inner periphery of the cylindrical shell  1  in corresponding relation thereto, there can be obtained the same effect as above. 
     Embodiment 3 
     Referring now to FIG. 17, there is illustrated embodiment 3 of the present invention. In this embodiment, both side knock and rear-end knock are possible, and there is used a slide member  17  of a one-piece structure. More specifically, the slide member  17  comprises a receptacle portion  17   a  located at the rear, an intermediate pipe  17   d  between the receptacle portion  17   a  and a slant portion  17   c  located at the front, and an extension  17   i  formed in front of the slant portion  17   c,  which components are formed integrally. A chuck  3  is press-fitted directly into the front end of the extension  17   i.  In this case, the return spring  10   a  used in the previous embodiments 1 and 2 may be omitted. 
     Embodiment 4 
     Referring now to FIG. 18, there is illustrated embodiment 4 of the present invention. In this embodiment, only side knock operation is possible, the rear end portion of a slide member  17  is short, and an eraser delivery mechanism is not used. According to embodiment 4, since the whole of the mechanical pencil can be made fairly short, it is possible to obtain a mini-mechanical pencil. Numeral  13   a  in the figure denotes a short eraser which also serves as a cap. 
     Embodiment 5 
     Referring further to FIG. 19, there is illustrated embodiment 5 of the present invention. In this embodiment, only side knock operation is possible like embodiments 2 and 4. Besides, the grip member used in the previous embodiments 1 to 4 is omitted to minimize the number of components used. 
     Since the present invention is constructed as above, a sufficient space is ensured at the rear of a side knock type mechanical pencil, and it is possible to enlarge the inside diameter of the lead tank and that of the slide member, which are limited in length, so as to permit even spare leads to be received therein, and also possible to provide a grip member. Moreover, there is obtained a mechanical pencil having not only the side knock function but also a rear-end knock function so that a lead can be pushed out easily even in the initial continuous knocking though this is difficult in the side knock operation. Further, there is obtained a side knock type mechanical pencil having a reduced number of components, less expensive and easy to assemble, which are attained by using a slide member of a one-piece structure.