LEAD CARTRIDGE FOR MECHANICAL PENCIL

Abstract: A lead cartridge has an opening and closing unit in which outward engaging portions (88, 89) are provided on a chuck type opening and closing mechanism which is divided into sections which have an inward elastic force and which is disposed on the lead cartridge. The outward engaging piece portions can move inwards against the inward elastic force along the diametrical direction thereof to open lead conducting holes when the cartridge is inserted into and engaged with a lead guide, whilst the outward engaging piece portions are restored by means of elastic force to move outwardly to close the lead conducting holes. When the outward engaging piece portions move inwards so that the lead conducting holes are opened, and on the other hand when the outward engaging piece portions are drawn out from the lead guide, these outward engaging piece portions are restored outwards by means of the elastic force so that the lead conducting holes are closed.

Description: This invention relates to a replaceable lead cartridge pencil with a closing mechanism. Recently, a so-called cassette type mechanical pencil has been proposed by means of which the lead members used can be exchanged and/or supplied by, for example, exchanging a whole cartridge 101 in which writing lead members are contained as shown in Figures 1 and 2, without accompanying refilling operation of such lead members one by one, so that the user's hands are not stained by the lead members. In such a conventional cassette type mechanical pencil, the lead cartridge 101 is simply provided with a cap 102 at the extreme end thereof. In this connection, exchange and/or supply of lead members for a mechanical pencil has been conducted in such a manner that the end cap 102 is first removed from the cartridge and thrown away, and the extreme end of the lead cartridge is fitted in an outer cylinder 103 of the mechanical pencil in its open state as shown in Fig. 2. Accordingly, there has been a problem that when the lead cartridge is inclined even slightly after removing the end cap 102, the lead members 104 can fall out. As a result, it is necessary while inserting the lead cartridge 101 into the outer cylinder 103 to maintain the lead cartridge 101 upright. Furthermore, in the case where the lead cartridge 101 is removed from the outer cylinder 103, there is a problem that when the lead members 104 are inclined downwards even slightly, the lead members 104 come out of the lead cartridge so that they remain in the outer cylinder 103. Moreover, a conventional cassette type mechanical pencil has a construction such that the lead cartridge 101 containing a number of lead members 104 is contained in the outer cylinder 103 together with a lead guide 105 into which the lead cartridge 101 is detachably inserted, as shown in Figure 2. In such a construction as described above, provision of a tapered bevelled portion 107 is required on the inner surface of the extreme end of the lead cartridge 101 for capturing lead members remaining in the outer cylinder 103. In addition, the inner wall of the outer cylinder 103 is required to form an inside protuberant wall portion 106 being different in level front the inner wall of the outer cylinder 103 as shown in Figure 2. For this reason, there has also been a problem that the diameter of the lead cartridge is restricted and hence the capacity for containing lead members is decreased. Extrusion moulding of the outer cylinder 103 with the protuberant wall portion 106 is impossible. As a result the outer cylinder must be injection moulded, a relatively expensive process. In this respect, the present applicant has attained the elimination of the above described problems by means of the opening and closing unit for the lead cartridge disclosed in Japanese Patent Publication No. 204692/1986 which was previously filed by the present applicant. In the opening and closing unit for the lead cartridge according to the above identified prior application, a chuck type opening and closing unit which extends forwardly and protrudes extensively from the extreme end of its lead cartridge has been described. However, such forward and extensive protrusion of the chuck type opening and closing mechanism as described above makes the appearance thereof unfavourable. Inconveniently the lead cartridge becomes longer by the protruded length of the chuck type opening and closing mechanism, as does the whole shaft length of a mechanical pencil to which said lead cartridge is applied. Another construction of lead cartridge has been proposed in DE-3401647. This patent discloses a lead cartridge with the structural features mentioned in the pre-characterising portion of claim 1 of this application. However, in the lead cartridge of DE-3401647, the closure means is provided by an elongate thin lever formed during manufacture from the tubular body of the pencil. The lever is biased by resilient pivot regions so that in a relaxed condition, i.e., when removed from the mechanical pencil, a jaw on the end of the lever co-operates with a jaw formed on the body to obstruct the lead passage. When inserted into the mechanical pencil, an inclined projection, formed on the end of the lever remote from the jaw, engages in wedging action within the pencil and opens the jaw. Because the capping structure is elastically relaxed in the closed condition (i.e., when the jaws obstruct the passage) it takes little force to open the lead passage and hence risk the loss of leads. Further assistance in understanding the present invention may be found in EP-A-0202942, which is a disclosure relevant by virtue of EPCa 54(3) and (4) in respect of Germany, France, Great Britain and Italy, but not Spain. The present invention seeks to provide a lead cartridge which overcomes the disadvantages of the conventional units described above. According to the present invention there is provided a lead cartridge to supply leads in a mechanical pencil according to claim 1. It will be appreciated that by resiliently biasing the closing portions, so that they are biased into engagement even in the closed condition, the aforementioned disadvantages of the prior art are alleviated. In a preferred embodiment of the lead cartridge the components of the capping structure are conveniently identical and may be assembled and secured to the cartridge body by being received into an aperture in an end of the tubular cartridge body. In the most preferred form of the lead cartridge the capping structure, with the exception of engaging portions provided on each closing portion to engage the lead guide, is received into the tubular body of the cartridge thereby further alleviating the risk of accidentally opening the axial passage during handling, protecting the capping structure against damage and improving the appearance of the lead cartridge. Embodiments of a lead cartridge for a mechanical pencil will now be described by way of example only, in order that the present invention may be fully understood: Fig. 3 is a schematic perspective view showing a cassette type mechanical pencil according to an example of the present invention; Fig. 4 is a sectional view showing a lead cartridge having a unitary capping structure in a mechanical pencil before assembly; Fig. 5 is a sectional view showing the lead cartridge of figure 4 after assembly; Fig. 6 is a sectional view taken along the line A -A of Fig. 4; Fig. 7 is a sectional view taken along the line B - B of Fig. 5; Fig. 8 is a side view showing a chuck type opening and closing unit according to the example shown in figure 3; Fig. 9 is a sectional view taken along the line C - C of Fig. 8. Fig. 10 is a sectional view taken along the line D -D of Fig. 8; Fig. 11 is a sectional view taken along the line D' - D' of Fig. 8; Fig. 12 is an elevation in section of a capping structure for use in a cartridge constructed in accordance with the present invention; Fig. 13 is an end view of the cartridge shown in Fig. 12; Fig. 14 is a sectional view taken along the line E - E of Fig. 12; Fig. 15 is a side view showing one component of the opening and closing mechanism of Fig. 12; Fig. 16 is a sectional view taken along the line F - F of Fig. 15; Fig. 17 is a sectional view taken along the line G - G of Fig. 17; Fig. 18 is a sectional view taken along the line H - H of Fig. 17; Fig. 19 is a view in the direction of the arrow I - I in Fig. 15; Fig. 20 is an end view of the component in Fig. 19; Fig. 21 is a sectional view taken along the line K - K of Fig. 19; Fig. 22 is a sectional view taken along the line J - J of Fig. 15; Fig. 23 is a side view of another opening and closing mechanism for use in a lead cartridge; Fig. 24 is a sectional view taken along the line L - L of Fig. 23; Fig. 25 is a sectional view taken along the line M - M of Fig. 23; Fig. 26 is a sectional view showing another embodiment of a lead cartridge; Fig. 27 is a sectional view showing the lead cartridge of Fig. 26 installed in the mechanical pencil; Fig. 28 is a sectional view taken along the line N - N of Fig. 26; Fig. 29 is a sectional view showing the lead cartridge of Fig. 26 installed in the mechanical pencil; Fig. 30 is a side view showing another chuck type opening and closing mechanism; Fig. 31 is a sectional view taken along the line P - p of Fig. 30; Fig. 32 is a sectional view taken along theline Q - Q of Fig. 30; Fig. 33 is a sectional view taken along the line Q' - Q' of Fig. 30; Fig. 34 is a side view showing a still further example of a chuck type opening and closing mechanism according to the present invention; Fig. 35 is an end view of the mechanism in figure 34; Fig. 36 is a side view showing one of the components of the chuck type opening and closing mechanism of Fig. 34; Fig. 37 is a plan view of the component in Fig. 36; Fig. 38 is a sectional view taken along the line R - R of Fig. 37; Fig. 39 is a sectional view showing essential parts for attaching a lead cartridge in a mechanical pencil before assembling the parts; Fig. 40 is a sectional view showing the essential parts for attaching a lead cartridge after assembling them; Fig. 41 is a side view showing an assembled state of a chuck type opening and closing mechanism; Fig. 42 is a sectional view taken along the line S - S of Fig. 41; Fig. 43 is a left side end view of Fig. 41; Fig. 44 is a side view showing only the under side chuck opening and closing member of Fig. 41; Fig. 45 is a sectional view taken along the line T - T of Fig. 44; Fig. 46 is a plan view of Fig. 45; and Fig. 47 is a sectional view taken along the line U - U of Fig. 46. A first example of the present invention will be described hereinbelow with reference to the accompanying drawings. In Fig. 3, reference numeral 1 designates an outer cylinder of a mechanical pencil, 2 a forward implement screwed with the extreme end of the outer cylinder 1, and 3 a part of a lead feeding mechanism placed in the outer cylinder 1, respectively, the lead feeding mechanism 3 being provided with a lead chuck 5 for fastening a lead member 4, and a lead guide 6 being meshed with the rear end of the lead chuck 5. In this case, a chuck coupler may be, of course, added between the lead chuck 5 and the lead guide 6. As shown in Figures 4 and 5, the generally cylindrical lead guide 6 is formed with, starting from its lower end, a lowermost internal cylindrical portion 60 which receives the upper end of lead chuck 5, a lead feeding hole 61 which is aligned with lead chuck 5, a central internal cylindrical portion 62 of internal radius (c), and an uppermost internal cylindrical portion 63 of larger diameter than the central internal cylindrical portion. The lead guide 6 functions to feed lead members one-by-one into lead chuck 5 from the central internal cylindrical portion 62. The uppermost internal cylindrical portion 63 receives the lower end of lead cartridge 7. The lead cartridge 7 is detachably meshed and connected with said lead guide 6 through the chuck type opening and closing mechanism 8. The opening and closing mechanism 8 according to the first example of the present invention has a upper cylindrical portion 80 the top of which is fitted into a larger diameter hole portion 7a at the lower end of the lead cartridge 7. In this case, a plurality of axially disposed ribs 80a, which are integrally place protrusively on the outer circumferential surface of upper cylindrical portion 80, are forced against and engaged with the inner circumferential surface of lower end larger diameter hole portion 7a as shown in Figure 4 and Figures 8 - 10. Furthermore, an outer circular protuberant portion 81 is integrally formed on the lower end of upper cylindrical portion 80, in the form of a step of larger diameter. The outer circular protuberant portion 81 abuts the lower end of the lead cartridge 7. A lower cylindrical portion 82 having smaller diameter than upper cylindrical portion 80 extending integrally from the lower end of the outer circular protuberant portion 81, coaxially. As shown in Figures 4, 5, 8 and 11, elastic (resilient) opening and closing piece portions 84 and 85, are formed, which are divided by a slit 83, extending from a substantially intermediate portion to the lower end of the front side cylindrical portion 82 along the diametrical direction thereof. On the end of cylindrical portion 82 respectively. The elastic opening and closing piece portions 84 and 85 have inward elatic force and are expandible and reducible in the diametrical direction, and on a shaft center portion of which are defined half lead conducting holes or lead conducting grooves 86 and 87, each having a symmetrically semicircular arcuate shape which is divided by the slit 83 into two sections, on the front end side of the elastic opening and closing piece portions. The half lead conducting holes 86 and 87 are arranged to form such inner diameter that lead members 4 having different diameters become conductible in case of elastic deformation of said elastic opening and closing piece portions 84 and 85 towards the direction for expanding the diameter thereof, whilst such a lead member 4 having the minimum diameter becomes unconductible in case of elastic deformation of said elatic opening and closing piece portions 84 and 85 towards the direction for reducing the diameter. In normal conditions, said elastic opening and closing piece portions 84 and 85 are closed by means of inward elastic force so as to mutually define the minimum diameter under a state of reducing the diameter. More specifically, two types of the opening and closing mechanism according to the present example is constructed dependent upon a diameter or diameters of lead members 4 to be used. (1) Use of the lead members 4 having only the same diameter one another: The half lead conducting holes 86 and 87 are opened in such that a single type of lead member 4 having each one diameter of, for example, 0.5 mm, 0.7 mm, 0.9 mm or the like can only be conducted through the resulting opening in the case when the undermentioned outward engaging piece portions 88 and 89 of the elastic opening and closing piece portions 84 and 85 are forcibly put in and engaged with a chuck containing hole 62 of the lead guide 6. (2) Use for both of lead members having different diameters (for example, 0.5 mm and 0.7 mm): The half lead conducting holes 86 and 87 are formed changeably in such that they occupy a space through which either of the lead members 4 can be conducted in the case when the outward engaging piece portions 88 and 89 are put in and engaged with the chuck containing hole 62, whilst the half lead conducting holes 86 and 87 takes a space through which both the lead members having different diameters cannot be conducted in case of releasing said forcible insertion and engagement. Half forwardly tapered holes 86a and 87a are defined on the forward ends of such half lead conducting holes 86 and 87 as described above, and the diameters of these half forwardly tapered holes 86a and 87a become gradually larger on the mutual front end sides thereof as shown in Figs. 4, 5 and 11. Furthermore, half rearwardly tapered holes 86b and 87b are defined on the rear ends of said half lead conducting holes 86 and 87, and the diameters of these half rearwardly tapered holes 86b and 87b become gradually larger on the mutual rear end sides thereof. Outward engaging piece portions 88 and 89 which extend oppositely to each other are integrally formed on the front end sides of said elastic opening and closing piece portions 83 and 84. More specifically, said slit 83 separates the half lead conducting holes 86 and 87 one another on the front end sides of said elastic opening and closing piece portions 84 and 85 with keeping away from said outward engaging piece portions 88 and 89, respectively, as shown in Figs. 6 and 7. Slits 83a and 83b which stand on different levels each other and are connected with the opposite ends of said slit 83 along the inside surfaces of the outward engaging piece portions 88 and 89 are defined on said elastic opening and closing piece portions 84 and 85 at the front end sides thereof. Accordingly, portions for shaping the outward engaging piece portions 88 and 89 on the front end sides of the elastic opening and closing piece portions 84 and 85 are separated by said slits 83, 83a, and 83b in different levels with each other. As a result, the outward engaging piece portion 88 of one of the elastic opening and closing piece portions, i.e. the portion 84 projects outwardly from the outer circumferential surface of the other elastic opening and closing piece portion 85, while the outward engaging piece portion 89 of the elastic opening and closing piece portion 85 projects outwardly from the outer circumferential surface of the other elastic opening and closing piece portion 84. In this case, said outward engaging piece portions 88 and 89 are formed in such that each length (a) or (b) defined between the extreme end of either portions 88 and 89 and each of their shaft center portions is longer than a radius (c) of the chuck containing hole 62 as shown in Figs. 4 and 7. Forward circular arcuate surface 88a and 89a are formed on the front of the respective outward engaging piece portions 88 and 89 as shown in Figs. 4, 5 and 8, whereby said outward engaging piece portions 88 and 89 can easily by forcibly put in the chuck containing hole 62 of said lead cartridge 7 by means of these forward circular arcuate surfaces 88a and 89a. Namely, the respective outward engaging piece portions 88 and 89 are forcibly inserted into the chuck containing hole 62 through the rear fitting hole 63 of the lead guide 6 in a usual condition where said elastic opening and closing piece portions 84 and 85 are deformed elastically by their respective inward elastic force along the direction of reducing the diameter to close both the half lead conducting holes 86 and 87 as shown in Figs. 4, 6, 8 and 9. As a result of the above forcible insertion, each of said outward engaging piece portions 88 and 89 moves along the direction in passing each other as shown in Figs. 4 and 7, and both of the elastic opening and closing piece portions 84 and 85 are elastically deformed integrally with their outward engaging piece portions 88 and 89 along the direction of expanding the diameter, so that the half lead conducting holes 86 and 87 are opened. In this case, said outward engaging piece portions 88 and 89 are resiliently fitted to and engaged with the chuck containing hole 62 of the lead guide 6, whereby the lead cartridge 7 is slipped in and set to the lead guide 6 through the opening and closing mechanism 8. Furthermore, gouged portions 84a and 85a each having a semicircular arcuate profile in its section are defined on the outer circumferential surfaces of said elastic opening and closing piece portions 84 and 85 extending over both the portions thereof as shown in Figs. 8, 9 and 11. As a result of the provision of these gouged portions 84a and 85a, the elastic opening and closing piece portions 84 and 85 become thinner in their diametrical directions, respectively, whereby they are easily deformed elastically so that resilient fitting and engagement as well as the release therefor of both the opening and closing piece portions 84 and 85 are carried out smoothly and positively with respect to the chuck containing hole 62 of the lead guide 6. It is to be noted that said gouged portions 84a and 85a are not indispensable elements. In operation, the lead cartridge 7 meshed with the lead guide 6 is drawn out together with the opening and closing mechanism 8 in case of exchanging lead members or confirming the presence of lead members during the use of a mechanical pencil. In this case, the resilient fitting and engagement of the outward engaging piece portions 88 and 89 of said opening and closing mechanism 8 are released with respect to the chuck containing hole 62, whereby each of the elastic opening and closing piece portions 84 and 85 is deformed elastically by means of its own inward elastic force in the direction of reducing the diameter. As a result, both the half lead conducting holes 86 and 87 are automatically closed until the closing diameter reaches that through which a lead member 4 cannot be conducted, in other words, when a lead member 4 having a diameter of 0.5 mm or more is used, both the holes are closed so as to have a closing diameter of 0.5 mm or less. Thus, there is no fear that either the lead members 4 in the lead cartridge 7 can slip out from the end opening thereof to leave them in the outer cylinder 1 or the lead members 4 drop outside the outer cylinder 1. Moreover, since there is no fear of leaving lead members, it is not required to provide a beveled portion such as a tapered portion or the like on the extreme end inner surface of the lead cartridge 7. As a consequence, there is not such problem that flow of a resin becomes insufficient due to a thin thickness of the extreme end inner surface in case of molding the lead cartridge 7 from manufacturing point of view. In addition, there is no need of provision of an inside protuberant portion in the outer cylinder 1 unlike a conventional mechanical pencil, and therefore the outer cylinder 1 may be obtained in accordance with inexpensive extrusion molding, besides a diameter of the lead cartridge 7 can be made larger so that a lead containing capacity can be significantly increased. Furthermore, if a lead member 4 remains in an area extending over the lead feeding hole 61 of the lead guide 6 and the half lead conducting holes 86 and 87 of the opening and closing mechanism 8, this remaining lead member 4 is chucked with the elastic opening and closing piece portions 84 and 85 to be drawn out, and such chucking operation being due to elastic deformation of the elastic opening and closing piece portions 84 and 85 in the direction of reducing the diameter by means of release for resilient fitting and engagement of the outward engaging piece portions 84 and 85 in the case of removal of said opening and closing mechanism 8. In these circumstances, when either the lead member 4 is taken out from the half lead conducting holes 86 and 87 after the lead cartridge 7 is drawn out or the lead member 4 is pushed into the lead cartridge 7, there is no fear of breaking said remaining lead member 4 at the time of exchanging the lead cartridge 7, or occurring clogging of the lead guide 6 with the broken lead member 4. In this connection, when a fresh lead cartridge 7 is pushed into the rear end of the outer cylinder 1, the outward engaging piece portions 88 and 89 of the opening and closing mechanism 8 are forcibly fitted in the rear side cylindrical portion 61 to be resiliently fitted and engaged, whereby the half lead conducting holes 86 and 87 of the opening and closing mechanism 8 are opened as mentioned above, so that supply of the lead members 4 becomes possible. As described above, in case of exchanging the lead cartridge 7, the half lead conducting holes 86 and 87 are closed before the outward engaging piece portions 88 and 89 are inserted into the chuck containing hole 62. Hence, there is no fear of springing out the lead members 4 from the lead cartridge 7 unlike a conventional lead cartridge. Moreover, there is not necessary to invert a mechanical pencil and conducting lead-exchanging operation under such inverted state while maintaining the lead cartridge 7 upwards. Thus, operation for exchanging the lead cartridge 7 can be very simply and easily carried out in a neat manner irrespective of an orientation of the mechanical pencil. Particularly, in the opening and closing mechanism 8, since the elastic opening and closing piece portions 84 and 85 which are divided into plural sections, respectively, are provided with the outward engaging piece portions 88 and 89 and are openable and closable in the diametrical direction thereof through these outward engaging piece portions 88 and 89, a fresh lead cartridge 7 containing either lead members 4 each having only the identical diameter with each other or lead members 4 having different diameters from one another, is attached to the lead guide 6 in accordance with the procedure as mentioned above, whereby these lead members 4 can be supplied. In other words, in said opening and closing mechanism 8, when the elastic opening and closing piece portions 84 and 85 are opened and closed through the outward engaging piece portions 88 and 89, a degree of opening and closing is adjusted, so that this opening and closing mechanism 8 can be used both for the lead members 4 each having only the identical diameter with each other and lead members 4 having different diameters from one another. An opening and closing mechanism 8 according to the second example of the present invention is shown in Figs. 12 - 22. This opening and closing mechanism 8 according to the second example has a construction the whole of which is divided into two sections in the diametrical direction along the axis thereof. More specifically, a rear side cylindrical portion 80 consists of half cylindrical portions 801 and 802 which are obtained by dividing the former into two sections along the axis thereof. In the case when these half cylindrical portions 801 and 802 are forcibly put in an extreme end larger diameter hole portion 7a in a lead cartridge 7 shown in Figs. 3 - 5, these half cylindrical portions 801 and 802 are concentrically assembled and incorporated, and in this case both of the portions are constructed in such that they are positively engaged with and fitted to each other at the time of their assemblage and incorporation. As the engaging means for assembling and incorporating said half cylindrical portions 801 and 802, an engaging convex portion 803 and an engaging concave portion 804 are integrally formed on either surface of the mating face composed of said half cylindrical portions 801 and 802, whilst an engaging concave portion 805 corresponding to said engaging convex portion 803 and an engaging convex portion 806 corresponding to said engaging concave portion 804 are integrally formed on the other surface of said mating face as shown in Figs. 12, 14, 15 and 17. Accordingly, when the engaging convex portion 803 as well as the engaging concave portion 804 of either half cylindrical portion 801 is fitted to and engaged with the engaging concave portion 805 as well as the engaging convex portion 806 of the other half cylindrical portion 802, respectively, both said half cylindrical portions 801 and 802 are exactly assembled and incorporated without any dislocation of them along the axial direction thereof. Thus, according to the second example of the present invention, assemblage of the opening and closing mechanism 8 as well as fitting and setting thereof can be simply carried out with respect to the lead cartridge 7. Furthermore, a plurality of engaging ribs 803a and 806a are integrally formed on the respective outer circumferential surfaces of said engaging convex portions 803 and 806 as shown in Figs. 15, 17 and 18. When said engaging convex portions 803 and 806 are fitted in and engaged with said engaging concave portions 804 and 805, these engaging ribs 803a and 806a are forced against and engaged with the inner circumferential surfaces of these engaging convex portions 803 and 806. For the above reason, slippage of said engaging convex portions 803 and 806 from said engaging concave portions 804 and 805 is prevented, so that said half cylindrical portions 801 and 802 can be more firmly combined integrally in case of assembling and incorporating both of them, whereby accuracy in assemblage of said opening closing mechanism 8 is much more improved, and the mechanism 8 can be simply and positively fitted and set to the lead cartridge 7. Besides the undermentioned elastic opening and closing piece portions 84 and 85 can also be smoothly and positively opened and closed. The elastic opening and closing piece portions 84 and 85 are integrally aligned on the extreme ends of such half cylindrical portions 801 and 802, respectively, through outer semicircular protuberant portions 81A and 81B each having a stepped larger diameter which are split into two pieces integrally with said half cylindrical portions 801 and 802. These elastic opening and closing piece portions 84 and 85 have been previously deformed plastically (elastically) by each angle ϑ towards the inside along the diametrical direction thereof as in Fig. 15 wherein either of said elastic opening and closing piece portions 84 and 85 is shown. In these circumstances, when said elastic opening and closing piece portions 84 and 85 are strongly pressed into contact with each other in case of assembling and incorporating them, both said elastic opening and closing piece portions 84 and 85 can be tightly assembled and incorporated. In this connection, when outward engaging piece portions 88 and 89 formed integrally on the front end sides of said elastic opening and closing piece portions 84 and 85 and which extend to the opposite sides in the diametrical directions, respectively, as shown in Figs. 12 and 13 are forcibly put in the lead guide 6 as shown in Figs. 3 - 5, these outward engaging piece portions 88 and 89 move in relative directions (the inside along the diametrical directions), and said elastic opening and closing piece portions 84 and 85 move to the outside along the diametrical directions thereof together with said outward engaging piece portions 88 and 89, so that the half lead conducting holes 86 and 87 are opened. Under such condition, when said outward engaging piece portions 88 and 89 are drawn out from said lead guide 6, said elastic opening and closing piece portions 84 and 85 are returned flexibly to the inside along the diametrical directions thereof, so that said half lead conducting holes 86 and 87 are closed. As described above, said elastic opening and closing piece portions 84 and 85 open and close said half lead conducting holes 86 and 87 by means of forcible insertion of said outward engaging piece portions 88 and 89 into said lead guide 6 as well as drawing them out from said lead guide 6. In this case, since the whole of the opening and closing mechanism 8 is split into two pieces as mentioned above, each radius of opening and closing motions in said elastic opening and closing piece portions 84 and 85 becomes larger so that these elastic opening and closing piece portions 84 and 85 are easily subjected to elastic deformation. In addition, since said elastic opening and closing piece portions 84 and 85 has sufficient flexible returning force due to plastic deformation which has been previously applied to said elastic opening and closing piece portions 84 and 85 inside along the respective diametrical directions as mentioned above, they are smoothly operated and as a result, the fatigue due to repetition of said opening and closing motions decreases. Moreover, since the whole opening and closing mechanism 8 has been split into two pieces, said outer engaging piece portions 88 and 89 as well as the defined portions of the half lead conducting holes 86 and 87 on the front end sides of said elastic opening and closing piece portions 84 and 85 may be separately formed with standing on different levels at a right angle as shown in Fig. 13. Thus, the half opening and closing mechanism 8 can simply be molded, besides the mating face of said half lead conducting holes 86 and 87 can also be tightly and positively joined to each other due to sufficient returning force of said elastic opening and closing piece portions 84 and 85, so that there is no fear that the lead members 4 in said elastic opening and closing piece portions 84 and 85 as well as the lead cartridge 7 slip off and drop therefrom. Figs. 23 - 25 illustrate the third example according to the present invention wherein the engaging convex portions 803 and 806 as well as the engaging concave portions 804 and 805 in the above second example are omitted. Therefore, a mechanical pencil according to the present third example can be served for use by only assembling and incorporating both of rear side semicircular cylindrical portions 801 and 802 in a concentrical manner, and forcibly putting them in the extreme end hole portion of a lead cartridge 7. According to the third example, a half opening and closing mechanism 8 can more simply be molded than in the case of the second example, besides the same functions and advantages can be obtained in respect of opening and closing functions of the elastic opening and closing piece portions 84 and 85 as in the case of the second example. It is to be noted that the constructions of said second and third examples other than those described above are the same with those of the first example, so that like reference numerals designate like or corresponding parts throughout these examples and the explanation has been omitted. Referring to Figs. 34 - 38, the fourth example according to the present invention will be described hereinbelow. In the fourth example, engaging convex portions 803′ and 806′ as well as engaging concave portions 804′ and 805′ are extensively formed along the axial directions, respectively, in the mating face of half cylindrical portions 801 and 802 as shown in Figs. 34, 36 and 37. Engaging ribs 804′a and 805′a are integrally extended from the inner circumferential surfaces of said engaging concave portions 804′ and 805′, whilst engaging grooves 803′a and 806′a for fitting and engaging said engaging ribs 804′a and 805′a therein and therewith are defined on the outside surfaces of said engaging convex portions 803′ and 806′. Hence, when the engaging convex portions 803′ and the engaging concave portion 804′ on either half cylindrical portion 801′ are fitted in the engaging concave portion 805′ and the engaging convex portion 806′ on the other half cylindrical portion 802′, respectively, their engaging ribs 804′a and 805′a are engaged with the engaging grooves 803′a and 806′a, so that both said half cylindrical portions 801′ and 802′ are exactly assembled and incorporated without any dislocation of them in the axial direction thereof. For the above reason, there is not such case where said engaging convex portions 803′ and 806′ are slipped off from said engaging concave portions 804′ and 805′, both said half cylindrical portions 801′ and 802′ can be more firmly combined integrally with each other in case of assembling and incorporating both of them, and accuracy in assemblage for an opening and closing mechanism 208 is much more improved to bring about simple and positive fitting and setting of said mechanism with respect to a lead cartridge 207, besides the undermentioned elastic opening and closing piece portions 284 and 285 can be smoothly and positively opened and closed. Furthermore, a wide width engaging projection 807′ having a semicircular arc in its profile and a sharpened engaging rib 808′ are alternately and integrally extended. Under such condition that said half cylindrical portion 801′ has been combined and incorporated with said half cylindrical portion 802′ and they have been fitted in the lead cartridge 207, said wide width engaging projection 807′ and said engaging rib 808′ are pressed against and engaged with the inner circumferential surface of said lead cartridge 207, and in this engagement state, a sufficient fitting pressure is obtained particularly by means of said wide width engaging projection 807′ between the inner circumferential surface of said lead cartridge 207 and this engaging projection 807′. As a result, said chuck type opening and closing mechanism 208 can be stably fitted and connected by means of such sufficient fitting pressure as described above. Elastic opening and closing piece portions 284 and 285 are integrally aligned on the extreme ends of said half cylindrical portions 801′ and 802′, respectively. These elastic opening and closing piece portions 284 and 285 have been previously deformed plastically (elastically) by each angle ϑ towards the inside along the diametrical direction thereof as in Fig. 36 wherein either of said elastic opening and closing piece portions 284 and 285 is shown. In these circumstances, when said elastic opening and closing piece portions 284 and 285 are strongly pressed into contact with each other in case of assembling and incorporating them, both said elastic opening and closing piece portions 284 and 285 can be tightly assembled and incorporated. In this connection, when outward engaging piece portions 288 and 289 formed integrally on the front end sides of said elastic opening and closing piece portions 284 and 285 and which extend to the opposite sides in the diametrical directions, respectively, as shown in Figs. 34 and 35 are forcibly put in the lead guide 206 as shown in Figs. 26 - 27, these outward engaging piece portions 288 and 289 move in relative directions (the inside along the diametrical directions), and said elastic opening and closing piece portions 284 and 285 move to the outside along the diametrical directions thereof together with said outward engaging piece portions 288 and 289, so that half lead conducting holes 286 and 287 are opened. Under such condition, when said outward engaging piece portions 288 and 289 are drawn out from said lead guide 206, said elastic opening and closing piece portions 284 and 285 are returned flexibly to the inside along the diametrical directions thereof, so that said half lead conducting holes 286 and 287 are closed. As described above, said elastic opening and closing piece portions 284 and 285 open and close said half lead conducting holes 286 and 287 by means of forcibly insertion of said outward engaging piece portions 288 and 289 into said lead guide 206 as well as drawing them out from said lead guide 206. In this case, since the whole of the opening and closing mechanism 208 is split into two pieces as mentioned above, each radius of opening and closing motions in said elastic opening and closing piece portions 284 and 285 becomes larger so that these elastic opening and closing piece portions 284 and 285 are easily subjected to elastic deformation. In addition, since said elastic opening and closing piece portions 284 and 285 has sufficient flexible returning force due to plastic deformation which has been previously applied to said elastic opening and closing piece portions 284 and 285 inside along the respective diametrical directions as mentioned above, they are smoothly operated and as a result, the fatigue due to repetition of said opening and closing motions decreases. Moreover, since the whole opening and closing mechanism 208 has been split into two pieces, said outer engaging piece portions 288 and 289 as well as the defined portions of the half lead conducting holes 286 and 287 on the front end sides of said elastic opening and closing piece portions 284 and 285 may be separately formed with standing on different levels at a right angle as shown in Fig. 35. Thus, the half opening and closing mechanism 208 can simply be molded, besides the mating face of said half lead conducting holes 286 and 287 can also be tightly and positively joined to each other due to sufficient returning force of said elastic opening and closing piece portions 284 and 285, so that there is no fear that the lead members 204 and in said elastic opening and closing piece portions 284 and 285 as well as the lead cartridge 207 slip off and drop therefrom. Next, the fifth example according to the present invention will be described hereinbelow by referring to Figs. 39 - 47 wherein a chuck type opening and closing mechanism 308 is provided with a lead conducting hole 380 and composed of symmetrical chuck opening and closing members 381 and 382 the whole of which is divided into two pieces in the diametrical direction thereof along the shaft center of the lead conducting hole 380 as shown in Figs. 39 - 47. It is, however, to be noted that although two-piece chuck opening and closing members 381 and 382 have been used in the present fifth example, of course, other members split into more pieces may also be employed. Rear side fitting portions 383 and 384 each of which is in the form of a stepped larger diameter half cylinder are integrally formed on the respective rear end sides of said chuck opening and closing members 381 and 382. Both of such chuck opening and closing members 381 and 382 as described above are combined and incorporated with each other, and the rear side fitting portions 383 and 384 thereof are fitted in and engaged with the lead cartridge 307 as shown in Fig. 1 . In this case, both of the rear side fitting portions 383 and 384 are constructed in such that they are positively engaged with and secured to each other in case of assembling and incorporating said chuck opening and closing members 381 and 382. As the engaging means, an engaging convex portion 385 and an engaging concave portion 386 are integrally formed on either surface of the mating face composed of said rear side fitting portions 383 and 384, whilst an engaging concave portion 387 corresponding to said engaging convex portion 385 and an engaging convex portion 388 corresponding to said engaging concave portion 386 are integrally formed on the other surface of said mating face as shown in Figs. 42 - 46. Engaging ribs 386a and 387a are integrally extended from the inner wall surfaces of said engaging concave portions 386 and 387, whilst engaging grooves 385a and 388a for engaging said engaging ribs 386a and 387a therewith are defined on the side wall surfaces of said engaging convex portions 385 and 388. Hence, when the engaging convex portion 385 and the engaging concave portion 386 on either rear side fitting portion 383 are fitted in the engaging concave portion 387 and the engaging convex portion 388 on the other rear side fitting portion 384, respectively, their engaging ribs 386a and 387a are engaged with the engaging grooves 385a and 388a, so that both said rear side fitting portions 383 and 384 are positively and securely engaged with and fixed to each other. Thus, both of said rear side fitting portions 383 and 384 are exactly assembled and incorporated without any dislocation of them in the axial direction thereof, so that assemblage of the chuck type opening and closing mechanism 308 as well as fitting and setting thereof can be simply carried out with respect to the lead cartridge 307. Furthermore, said rear side fitting portions 383 and 384 are constructed in such that they are positively fitted in and engaged with said lead cartridge 307. As that engaging means, wide width engaging projections 383a and 384a each having a semicircular arc in its profile and engaging ribs 383b and 384b are alternately and integrally extended from the outer circumferential surfaces of said rear side fitting portions 383 and 384 as shown in Figs. 42 and 45. Under such condition that said rear side fitting portions 383 and 384 are fitted in the lead cartridge 307, said wide width engaging projections 383a and 384a as well as said engaging ribs 383b and 384b are pressed against and engaged with the inner circumferential surface of said lead cartridge 307, and in this engagement state, a sufficient fitting pressure is obtained particularly by means of said wide width engaging projections 383a and 384a between the inner circumferential surface of said lead cartridge 307 and this engaging projections 383a and 384a. As a result, said chuck type opening and closing members 381 and 382 can be stably fitted in and connected to said lead cartridge 307 under such assembled and incorporated state as mentioned above. Inwardly projecting opening and closing portions 381a and 382a are integrally formed on the inner circumferential surfaces of said chuck opening and closing members 381 and 382 at the front side thereof. Tapered portions 381b and 382b are formed on the forward portions of said inwardly projecting opening and closing portions 381a and 382a, and each front end side of these tapered portions 381b and 382b being expanded so as to become gradually larger diameter and being fitted in and adjusted to a tapered portion 362a of a rear side inner cylindrical portion 362. Moreover, said chuck opening and closing members 381 and 382 have inward elastic force along a direction in which said inwardly projecting opening and closing portions 381a and 382a are closed, so that the former members are expandible and reducible. Since the chuck type opening and closing mechanism 308 consists of two-piece chuck opening and closing members 381 and 382, a lead conducting hole 380 is composed of half lead conducting holes 380a and 380b. These half lead conducting holes 380a and 380b are constructed so as to possess such inner diameter through which lead members 304 including those having different diameters can be conducted in the case where said chuck opening and closing members 381 and 382 are elastically deformed towards the expanding direction. On the other hand, said inner diameter is also arranged in such that a lead member 304 having the minimum diameter cannot be conducted by means of said inwardly projecting opening and closing portions 381a and 382a in the case where said chuck opening and closing members 381 and 382 are elastically deformed towards the reducing direction. In order that both of said chuck opening and closing members 381 and 382 are tightly pressed into contact with each other by means of the inward elastic force thereof in case of the assemblage and incorporation of them, besides said chuck opening and closing members 381 and 382 are allowed to be elastically deformable in the expanding or reducing direction, gouged portions 381c and 382c each having a substantially semicircular arc in its profile and defined on the outer circumferential surfaces in a mutual joint portion of said chuck opening and closing members 381 and 382 extending over these both members as shown in Figs. 41, 44, 46 and 47. Furthermore, the outer circumferential surfaces of said chuck opening and closing members 381 and 382 are formed into curved portions 381d and 382d expanding outwardly between both the gouged portions 381c and 382c. The jointed portion of said chuck opening and closing members 381 and 382 is thinned by means of said gouged portions 381c and 382c, and the outer circumferential surfaces 381d and 382d of said chuck opening and closing members 381 and 382 are formed into expanded and curved surfaces 381d and 382d. Moreover, said chuck opening and closing members 381 and 382 have been previously deformed elastically by each angle ϑ towards the inside along the diametrical direction thereof as shown in Fig. 44. In these circumstances, when said chuck opening and closing members 391 and 382 are strongly pressed into contact with each other by means of their inward elastic force in case of assembling and incorporating them, both said chuck opening and closing members 391 and 382 can be tightly assembled and incorporated. In addition, both of the elastic deformation of the chuck opening and closing members 381 and 382 towards the direction of expanding the diameter in case of fitting them in the rear side inner cylindrical portion 362 of said lead guide 306 as well as the elastic deformation of the chuck opening and closing members 381 and 382 towards the direction of reducing the diameter in case of drawing them from said rear side inner cylindrical portion 362 are smoothly and positively performed. It is, however, to be noted that said gouged portions 381c and 382c are not indispensable elements for the present invention. In normal condition, said chuck opening and closing members 381 and 382 are closed by means of inward elastic force in such that both of the half lead conducting holes 380a and 380b define the minimum diameter under a state of reducing the diameter. More specifically, two types of the opening and closing mechanism according to the present example is constructed dependent upon a diameter or diameters of lead members 304 to be used. (1) Use of the lead members 304 having only the same diameter one another: The half lead conducting holes 380a and 380b are opened in such that a single type of lead member 304 having each one diameter of, for example, 0.5 mm, 0.7 mm, 0.9 mm or the like can only be conducted through the resulting opening in the case when the tapered portions 381b and 382b on the extreme end of the chuck opening and closing members 381 and 382 are forcibly put in and engaged with the rear side inner cylindrical portion 362 of the lead guide 306. (2) Use for both of lead members having different diameters (for example, 0.5 mm and 0.7 mm): The half lead conducting holes 380a and 380b are formed changeably in such that they occupy a space through which either of the lead members 304 can be conducted in case of said forcible insertion and engagement, whilst the half lead conducting holes 380a and 380b takes a space through which both the lead members having different diameters cannot be conducted in case of releasing said forcible insertion and engagement. In operation, the lead cartridge 307 meshed with the lead guide 306 is drawn out together with the chuck type opening and closing mechanism 308 in case of exchanging lead members or confirming the presence of lead members during the use of a mechanical pencil. In this case, when each of the chuck opening and closing members 391 and 392 is deformed elastically by means of its own inward elastic force in the direction of reducing the diameter, both the half lead conducting holes 380a and 380b are automatically closed until the closing diameter reaches that through which a lead member 304 cannot be conducted, in other words, when a lead member 304 having a diameter of 0.5 mm or more is used, both the holes are closed so as to have a closing diameter of 0.5 mm or less. Thus, there is no fear that either the lead members 304 in the lead cartridge 307 are slipped off from the end opening thereof to leave them in the outer cylinder 301 or the lead members 304 drop outside the outer cylinder 301. Moreover, since there is no fear of leaving lead members, it is not required to provide a beveled portion such as a tapered portion or the like on the extreme end inner surface of the lead cartridge 307. As a consequence, there is not such problem that flow of a resin becomes insufficient due to a thin thickness of the extreme end inner surface in case of molding the lead cartridge 307 from manufacturing point of view. In addition, there is no need of provision of an inside protuberant portion in the outer cylinder 301 unlike a conventional mechanical pencil, and therefore the outer cylinder 301 may be obtained in accordance with inexpensive extrusion molding, besides a diameter of the lead cartridge 307 can make larger so that a lead containing capacity can be significantly increased. Furthermore, if a lead member 304 remains in an area extending over a lead feeding hole 364 of the lead guide 396 and the half lead conducting holes 380a and 380b of the chuck type opening and closing mechanism 308, this remaining lead member 304 is chucked with the inwardly projecting opening and closing members 381a and 382a of said chuck opening and closing members 381 and 382 to be drawn out, and such chucking operation being due to elastic deformation of the chuck opening and closing members 381 and 382 in the direction of reducing the diameter by means of removal of said opening and closing mechanism 308. In these circumstances, when either the lead member 304 is taken out from the half lead conducting holes 380a and 380b after the lead cartridge 307 is drawn out or the lead member 304 is pushed into the lead cartridge 307, there is no fear of breaking said remaining lead member 304 at the time of exchanging the lead cartridge 307, or occurring clogging of the lead guide 306 with the broken lead member 304. In this connection, when a fresh lead cartridge 307 is pushed into the rear end of the outer cylinder 301, the tapered portions 381b and 382b on the extreme ends of the chuck opening and closing members 381 and 382 are forcibly fitted in the rear side inner cylindrical portion 362 of the lead guide 306 to be resiliently fitted and engaged, whereby the half lead conducting holes 380a and 380b of the chuck opening and closing members 381 and 382 are opened as mentioned above, so that supply of the lead members 304 becomes possible. As described above, in case of exchanging the lead cartridge 307, the half lead conducting holes 380a and 380b are closed before the chuck opening and closing members 381 and 382 are inserted into the rear side inner cylindrical portion 362. Hence, there is no fear of springing out the lead members 304 from the lead cartridge 307 unlike a conventional lead cartridge. Moreover, there is not necessary for inverting a mechanical pencil and conducting lead-exchanging operation under such inverted state while maintaining upwardly the lead cartridge 307. Thus, operation for exchanging the lead cartridge 307 can be very simply and easily carried out in a neat manner irrespective of an orientation of the mechanical pencil. Particularly, in said chuck type opening and closing mechanism 308, since a plurality of the chuck opening and closing members 381 and 382 are assembled and incorporated, and these chuck opening and closing members 381 and 382 have inwardly directed elastic force thereby being opened and closed in the diametrical direction thereof. Thus, a fresh lead cartridge 307 containing either lead members 304 each having only the identical diameter with each other, as a matter of course, or lead members 304 having different diameters one another is attached to the lead guide 306 in accordance with the procedure as mentioned above, whereby these lead members 304 can be supplied. In other words, in said chuck type opening and closing mechanism 308, a degree of opening and closing for the chuck type opening and closing members 381 and 382 as well as the half lead conducting holes 380a and 380b is adjusted by means of its own elastic force, so that this opening and closing mechanism 308 can be used both for the lead members 304 each having only the identical diameter with each other and lead members 304 having different diameters from one another. As mentioned above, according to the present invention, outward engaging piece portions are provided on a chuck type opening and closing mechanism which is divided into plural sections in the diametrical direction and has inward elastic force and which is disposed on said lead cartridge, and said outward engaging piece portions moving inwardly along the diametrical direction thereof thereby to open lead conducting holes in case of forcible insertion into and engagement with a lead guide, whilst said outward engaging piece portions returning elastically to move outwardly along the diametrical direction thereof thereby to close said lead conducting holes in case of release for said forcible insertion and engagement. As a result, the lead conducting holes are opened in the case when these outward engaging piece portions are resiliently fitted to and engaged with the lead guide, and on the other hand said lead conducting holes are closed in the case when the outward engaging piece portions are not engaged with said lead guide. Thus, there is no fear of springing a lead member out from the lead cartridge in case of exchanging therefor or the like event, besides since a chuck type opening and closing mechanism is closed in case of exchanging the lead cartridge, such lead members remaining in a writing utensil can be drawn out. In these circumstances, there is no fear of breaking said remaining lead members, or occurring clogging of the writing utensil with such broken lead members, so that the lead cartridge can be very simply and easily exchanged. Moreover, a lead cartridge may contain either lead members having, of course, only the same diameter with each other, or lead members having different diameters from one another, because of the provision, particularly, of said opening and closing mechanism according to the present invention. In addition, there is no parts to be thrown away such as a cap for conventional lead cartridge and the like parts, besides it is not required to provide a thick protuberant wall portion on its outer cylinder in the writing utensil according to the present invention. Hence, in the present invention, many excellent advantages such that the outer cylinder of a writing utensil may be subjected to extrusion molding, and that an amount for containing lead member in the lead cartridge can be increased. Furthermore, according to the present invention, since a chuck type opening and closing mechanism is inserted and contained in its lead cartridge extending over substantially the whole length thereof, the appearance of said lead cartridge is improved, besides there is not such case where the lead cartridge becomes lengthy because of the presence of said chuck type opening and closing mechanism, so that a shaft length of the mechanical pencil to which is applied the lead cartridge of the invention can also be shortened. Yet further, in accordance with the present invention, a chuck type opening and closing mechanism mounted on its lead cartridge is composed of chuck opening and closing members each having inward elastic force, and said chuck opening and closing members being obtained by dividing said chuck type opening and closing mechanism along the axis of its lead conducting holes in the diametrical direction thereof, so that said chuck opening and closing members can easily be molded and a construction of the molding die to be used may be simplified, and as a consequence the manufacturing cost for such writing utensils can significantly be reduced. Another example of the invention is illustrated in Figures 26 to 33. The opening and closing mechanism 208 according to this example of the present invention has a rear side cylindrical portion 280 the rear side of which is fitted into a recessed hole portion 207a at the lower end of the lead cartridge 207. A plurality of axially disposed ribs 280a which protrude from the surface of rear side cylindrical portion 280 are forced against and engaged with the inner circumferential surface of the recessed hole portion 207a as shown in Figures 26 and 27. Also axially protuberant portions 281 are formed on the outside surface of the rear side cylindrical portion 280. A front side cylindrical portion 282 extends from the rear side cylindrical portion 280, and is divided in to elastic opening and closing piece portions 284 and 285 by a slit 283 extending from a substantially intermediate portion to the front end of the front side cylindrical portion 282. These elastic opening and closing piece portions 84 and 85 have inward elastic force and are expandible and reducible in the diametrical direction, and on a shaft center portion have half lead conducting holes 286 and 287, each having an arcuate shape. The half lead conducting holes 286 and 287 are arranged to form such inner diameter that lead members 4 having different diameters become conductible in case of elastic deformation of the elastic opening and closing piece portions 84 and 85 outwards, whilst such a lead member 4 having the minimum diameter becomes unconductible in case of elastic deformation of the elastic opening and closing piece portions 284 and 285 inwards to the closed portion. In normal conditions the elastic opening and closing piece portions 284 and 285 are closed by means of inward elastic force so as to mutually define the minimum diameter under a state of reducing the diameter. Tapered holes 286a and 287a are defined on the forward ends of the half lead conducting holes 286 and 287. Also tapered holes 286b and 287b are defined on the rear ends of the half lead conducting holes 286 and 287. Outward engaging piece portions 288 and 289 which extend oppositely to each other are integrally formed on the front end sides of said elastic opening and closing piece portions 284 and 285. More specifically, the slit 283 separates the half lead conducting holes 286 and 287 from one another on the front end sides of the elastic opening and closing piece portions 284 and 285 with keeping away from said outward engaging piece portions 288 and 289, respectively, as shown in Figures 28 and 29. Side slites 283a and 283b offset from one another are connected with the opposite ends of the slit 283 on the inside surfaces of the outward engaging piece portions 288 and 289. The outward engaging piece portion 288 of the elastic opening and closing piece portion 284 projects beyond the outer surface of the portion 285, while the outward engaging piece portion 289 of the elastic opening and closing piece portion 285 projects outwards beyond the surface of the portion 284. The outward engaging piece portions 288 and 289 are formed in such that each length (a) or (b) defined between the end of the portions 88 or 89 and each of their shaft center portions is longer than a radius (c) of the chuck receiving hole 262 as shown in Figures 26 and 29. Forward circular arcuate surfaces 288a and 289a are formed on the front of the respective outward engaging piece portions 288 and 289 as shown in Figure 26, whereby the outward engaging piece portions 288 and 289 can easily be put in the chuck containing hole 262 of the lead cartridge 207. Furthermore, the open and closing portions 284, 285 have gouged portions 284a and 285a each having a semicircular arcuate profile in section and also outwardly curved sections 284b, 285b. The major part of the opening and closing mechanism 208 is contained with the lead cartridge 207, with the tip of the opening and closing portions 284, 285 projecting beyond the end of the lead cartridge 207. The outward engaging portions project beyond the end of the lead cartridge 207 so that they can engage in the chuck receiving section 262 of the lead guide 206.

Claims: A lead cartridge to supply leads in a mechanical pencil comprising a cartridge body (7, 207, 307) wherein a plurality of lead members (4, 204, 304) can be stored and having a capping structure (8, 208, 308) which provides an axial passage for the transfer of the lead members (4, 204, 304) between the cartridge body (7, 207, 307) and the mechanism of the pencil; said capping structure (8, 208, 308) having closure means to obstruct the passage of the lead members through the axial passage when the cartridge is separated from the pencil, the closure means being elastically deformed to open the axial passage by engagement with a lead guide (6, 206, 306), on insertion of the cartridge into the pencil, characterised in that the capping structure (8, 208, 308) is assembled from two axially opposed components secured to the cartridge body (7, 207, 307), each of the components comprising a closing portion (84, 85; 284, 285; 381, 382) adapted to be resiliently biased into engagement with the other of the closing portions on assembly of the capping structure, whereby the closing portions (84, 85; 284, 285; 381, 382) cooperate to form the closure means, each closing portion (84, 85; 284, 285; 381, 382) being arranged to engage the lead guide (6, 206, 306) in the pencil whereby the closing portions are displaced in opposition to the bias to open the axial passage, each component of the capping structure (8, 208, 308) being formed with an upper semi-cylindrical portion (383, 384; 801, 802) to form a cylindrical end to the capping structure (8, 208, 308), on assembly, whereby it is adapted to press fit into the cartridge body (7, 207, 307) to secure the capping structure (8, 208, 308), and each of the semi-cylindrical portions (383, 384; 801, 802) being provided with a projection (385, 388; 803, 806) which locates in a complementary recess (386, 387; 804, 805) in the other of the semi-cylindrical portions. A lead cartridge according to claim 1, wherein the components are identical to each other. A lead cartridge according to claim 1 or claim 2, wherein at least a part of the closing portions (284, 285; 381, 382) are surrounded by part of the cartridge body (207, 307). A lead cartridge according to any one of claims 1 to 3, wherein each projection (385, 388; 803, 806) is formed with grooves (385a, 388a; 803'a) which are adapted to engage with ribs (386a, 387a; 804'a) in the complementary recess (386, 387; 804, 805). A lead cartridge according to any preceding claim, wherein each closing portion (84, 85; 284, 285) has an engaging portion (88, 89; 288, 289) extending outwardly to engage with an axially facing surface of the lead guide (6, 206) of the pencil in wedging action whereby the closing portion is displaced diametrically away from the axis to open the lead passage. A lead cartridge according to any preceding claim, wherein each closing portion (84, 85; 284, 285; 381, 382) is adapted to provide the bias by being prebent to make an angle (ϑ) with respect to the axis. A lead cartridge according to any preceding claim, wherein each of the closing portions (84, 85; 284, 285; 381, 382) is formed with gauged portions (84a, 85a; 284a, 285a; 38lc, 382c) having an arcuate profile, in section, on the outer surface. Claims for the following contracting state: ES A lead cartridge to supply leads in a mechanical pencil comprising: a cartridge body (7, 207, 307) wherein a plurality of lead members (4, 204, 304) can be stored and having a capping structure (8, 208, 308) which provides an axial passage for the transfer of the lead members (4, 204, 304) between the cartridge body (7, 207, 307) and the mechanism of the pencil; said capping structure (8, 208, 308) having closure means to obstruct the passage of the lead members through the axial passage when the cartridge is separated from the pencil, the closure means being elastically deformed to open the axial passage by engagement with a lead guide (6, 206, 306), on insertion of the cartridge into the pencil, characterised in that; the capping structure (8, 208, 308) is assembled from two axially opposed components secured to the cartridge body (7, 207, 307), each of the components comprising a closing portion (84 & 85, 284 & 285, 381 & 382) adapted to be resiliently biased into engagement with the other of the closing portions on assembly of the capping structure, whereby the closing portions (84 & 85, 284 & 285, 381 & 382) cooperate to form the closure means, each closing portion (84 & 85, 284 & 285, 381 & 382) being arranged to engage the lead guide (6, 206, 306) in the pencil whereby the closing portions are displaced in opposition to the bias to open the axial passage. A lead cartridge according to claim 1 wherein the components are identical to each other. A lead cartridge according to claim 1 or claim 2 wherein at least a part of the closing portions (284 & 285, 381 & 382) are surrounded by part of the cartridge body (207, 307). A lead cartridge according to any one of claims 1 to 3 wherein each component of the capping structure (8, 208, 308) is formed with an upper semi-cylindrical portion (383 & 384, 801 & 802) to form a cylindrical end to the capping structure (8, 208, 308), on assembly, adapted to press fit into the cartridge body (7, 207, 307) to secure the capping structure (8, 208, 308). A lead cartridge according to claim 4 wherein each of the semi-cylindrical portions (383& 384, 801 & 802) are provided with a projection (385 & 388, 803 & 806) which locates in a complementary recess (386 & 387, 804 & 805) in the other of the semi-cylindrical portions. A lead cartridge according to claim 5 wherein each projection (385 & 388, 803 & 806) is formed with grooves (386a & 388a, 803'a) which are adapted to engage with ribs (386a & 387a, 804'a) in the complementary recess (386 & 387, 804 & 805). A lead cartridge according to any preceding claim wherein each closing portion (84 & 85, 284 & 285) has an engaging portion (88 & 89, 288 & 289) extending outwardly to engage with an axially facing surface of the lead guide (6, 206), of the pencil, in wedging action whereby the closing portion is displaced diametrically away from the axis to open the lead passage. A lead cartridge according to any preceding claims wherein each closing portion (84 & 85, 284 & 285, 381 & 382) is adapted to provide the bias by being pre-bent to make an angle (ϑ) with respect to the axis. A lead cartridge according to any preceding claim wherein each of the closing portions (284, 285) is formed with gauged portions (84a & 85a, 284a & 285a, 38lc & 382c) having an arcuate profile, in section, on the outer surface.

Inventors: KAGEYAMA, HIDEHEI C/O KOTOBUKI & CO., LTD., KOBAYASHI, SABURO C/O KOTOBUKI & CO., LTD., MITSUYA, YOSHIHIDE C/O KOTOBUKI & CO., LTD., Kageyama, Hidehei c/o Kotobuki &amp; Co., Ltd., Kobayashi, Saburo c/o Kotobuki &amp; Co., Ltd., Mitsuya, Yoshihide c/o Kotobuki &amp; Co., Ltd.
Applicants: KOTOBUKI & CO., LTD.
Application year: 1987
Main classification: B43K21
IPC codes: B43K21