Abstract:
An applicator ( 1 ) is provided, such that an end closure or a proximal plug ( 3 ) fitted in a cylindrical body ( 2 ) of the applicator can be removed easily without use of a coin or the like tool. Repeated easy operations for attaching and detaching the plug will not impair firm engagement of the plug with the body, protecting the plug from inadvertently slipping off.  
     The plug ( 3 ) is a double-cylinder composed of an outer tube ( 15 ) combined with an inner tube ( 16 ), and two slots ( 30,31 ) are formed in the outer tube so as to extend from its rear end to, and desirably across, a flange ( 25 ). Fore ends of the slots continue to a cutout ( 35 ). An exposed part of the plug can be pinched in part to reduce its apparent diameter, thus making the outer tube sections ( 40,41 ) distort themselves elastically towards each other, thus facilitating removal of the plug.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an applicator including writing and marking instruments such as line markers, felt pens, fountain pens and ballpoint pens, and more particularly relates to an applicator that comprises a cylindrical body whose open end is closed with a plug such as an end closure.  
           [0003]    2. Description of Related Art  
           [0004]    Most of the line markers and the like applicators have been of the disposable type to be discarded when their ink was consumed almost completely, regardless of their bodies reusable enough. Therefore, some users have wanted or tried to refill such line markers or the like with a fresh amount of ink so as to use them again. Certain proposals made in view of this demand relate to applicators of an improved structure such that an end closure (also called “a proximal plug”) is capable of disengagement from the cylindrical body when refilling the applicator with the ink.  
           [0005]    The Japanese Patent Laying-Open Gazette No. 2001-105781 discloses an example of such an improved structure, wherein a deep groove is formed between an end of a cylindrical body and a penpoint holder or a proximal plug. A coin or the like hand tool can be inserted easily into this groove when the plug is to be taken off.  
           [0006]    Thus, the above-described art applicators have necessitated coins or the like tools in removing their plugs from cylindrical bodies. Further, a lever action generated by such an operation has caused a strong stress to permanently deform the plug or an end portion of the cylindrical body adjacent to the groove. Repeated detachment of a plug will deteriorate such end portions more and more, until making it impossible to mount again the plug on the cylindrical body or making its reattached plug very prone to slip off.  
         SUMMARY OF THE INVENTION  
         [0007]    An object of the present invention is therefore to provide such an applicator that its plug can readily be taken off its cylindrical body, without need of any handy tool such as a coin. The improvement has to be designed herein such that the plug is capable of repeated detachment and reattachment operations, while being protected from any serious permanent deformation and any inadvertent slipping off. In this specification, a plug can be a unitary member or can be made up of a plurality of parts.  
           [0008]    In a first mode of the invention made to achieve this object, the applicator may comprise a cylindrical body to be filled with a liquid for application, and a plug that may be either or both of distal and proximal plugs. The plug, that may be exemplified herein as the proximal plug, is detachably attached to an open end of the applicator&#39;s cylindrical body and exposed in part to the outside. Characteristically to the present applicator, its plug may have at least one slot formed therein and extending axially of its cylindrical body such that the exposed part of the plug can be pinched centripetally to cause its elastic and temporary deformation. Owing to this feature, an inner region of the plug in a pressed contact with the cylindrical body will be forced to reduce its overall radius of curvature to thereby enable and facilitate removal of the plug.  
           [0009]    Such a longitudinal slot or slots will render the applicator&#39;s plug ready to distortion. If the exposed portion of the plug is pinched in a centripetal direction, then the slot or slots will permit this portion to distort itself by a distance corresponding to width of each slot. An elastic decrease in overall diameter of the plug is thus caused in the centripetal direction, thereby producing a sufficient annular gap between the cylindrical body and the plug fitted therein, or at least weakening a contact pressure between them to such an extent as making it easy to detach the plug.  
           [0010]    In this mode of carrying out the present invention, users of this applicator need not to use any tool or coin when they repeat to attach and detach the plug, and what is more surprising, it will never slip off inadvertently during usage or storage of this applicator. The slots may not necessarily have a uniform width between their longitudinal ends, but may each be of a varying width (as in V-shaped slots).  
           [0011]    In a second mode of the present invention, the applicator may comprise a cylindrical body to be filled with a liquid for application, and a plug selected from the group consisting of distal and proximal plugs. The plug is detachably attached to an open end or ends of said body and exposed in part to the outside. Characteristically to this applicator, its plug may have at least one flexible portion extending axially of its cylindrical body such that the exposed part of the plug can be pinched centripetally to cause elastic and temporary deformation thereof Owing to this feature, an inner region of the plug in a pressed contact with the cylindrical body will also reduce its overall radius of curvature to facilitate removal of the plug from this body.  
           [0012]    The term ‘flexible portion or portions’ used herein means portions that are more ready to elastic distortion than other areas adjoining to or surrounding them, due to a decreased thickness of said portion or portions, or due to a softer material forming same.  
           [0013]    Such longitudinal flexible portions will render the applicator&#39;s plug ready to distortion, similarly to the applicator in the first mode of the invention. If the exposed portion of the plug is pinched in a centripetal direction, then the flexible portion or portions will permit the exposed portion to distort itself by a distance corresponding to width of each flexible portion. An elastic decrease in overall diameter of the plug is thus caused in the centripetal direction, thereby producing a sufficient annular gap between the cylindrical body and the plug fitted therein, or at least weakening a contact pressure between them to such an extent as making it easy to detach the plug.  
           [0014]    Preferably, the plug may be a proximal plug, and one of this plug and the cylindrical body has a protrusion formed integral therewith and at a portion contacting the mating body or plug. Correspondingly, the other of the cylindrical body and the proximal plug has an engageable portion that is a lug or a recess facing such a protrusion. Each longitudinal slot or flexible portion extends over and beyond the protrusion or engageable portion.  
           [0015]    With the plug being fitted in the cylindrical body, the protrusion will be kept in engagement with the recess or lug, that is the engageable portion, so as to inhibit the plug from slipping off said body during normal use of the applicator. Since the plug has longitudinal slots formed therein and extending beyond the protrusion or engageable portion, the region where such a protrusion or portion is located will also show a significant decrease in overall diameter when the exposed region of plug is pinched centripetally. Thus, disengagement of said protrusion from said engageable portion is facilitated to enable smooth detachment of the plug from the applicator body.  
           [0016]    Also preferably, each slot has an end opened in the exposed end face of the plug. This exposed end is a rear end of the plug if it is a proximal plug, or a fore end of the plug if it is a distal plug, and in any case, being its outer end remote from a middle region of this applicator.  
           [0017]    By virtue of the slot or slots having their end or ends opened in the exposed end face of the plug in the described example, the plug will stand in part in a cantilevered state easy to show distortion and consequently ready to removal from the cylindrical body.  
           [0018]    Alternatively, the longitudinal slot or slots may be disposed in a middle region of the plug so that it has or they have opposite closed ends.  
           [0019]    Even in this case, the plug&#39;s middle region is flexible enough, as compared with a middle region devoid of such slots.  
           [0020]    Preferably, the slot or slots may be formed in a peripheral wall of the plug and this wall defines therein a central cavity.  
           [0021]    The central cavity will permit centripetal displacement of portions of the peripheral wall when it elastically deforms itself, thus further rendering the plug easy to distortion and removal.  
           [0022]    Also preferably, two or more such longitudinal slots are formed in the plug, and at least one tying slot bridges the two adjacent longitudinal slots.  
           [0023]    In this case, peripheral wall regions of the plug, that are almost surrounded each by such longitudinal and tying slots, are in a cantilevered state to be much easier to distortion.  
           [0024]    It may be more preferable that the two or more longitudinal slots are connected one to another by at least one tying slot continuing from one ends of the two adjacent longitudinal slots.  
           [0025]    Also in this case, the longitudinal slots having one ends connected to each other by the tying slot will elongate in axial direction the cantilevered peripheral wall regions, thus making flexible deformation (viz., distortion) thereof more easier.  
           [0026]    It also is preferable that two or more longitudinal slots are formed and at least two of them have inner ends and closed outer ends, with the ‘inner ends’ being connected one to another by a tying slot. This inner end is a fore end of the plug if it is a proximal plug, or a rear end of the plug if it is a distal. plug. In other words, the inner end is located nearer or close to the applicator&#39;s middle height in the drawings than an ‘outer end’ is.  
           [0027]    In this case, the at least two longitudinal slots having the closed ends in addition to the inner ends connected to each other by the tying slot will provide a tongue-like cantilevered wall region. Outer end face portions of the peripheral wall close the slots&#39; outer ends so as to serve as fulcrum-like supports for each tongue-like region, thereby rendering flexible deformation (viz., distortion) thereof much easier and smoother.  
           [0028]    The plug in this applicator may further have one cutout or more cutouts each in communication with the one or more of the slots.  
           [0029]    Such a cutout or cutouts noticeably shortens or shorten the boundary between the remainder of peripheral wall and each tongue-like region surrounded thereby. These cutouts, that may preferably be slots convenient to manufacture, will also enhance capability of flexible deformation (viz., distortion) of surrounded cantilevered regions.  
           [0030]    It also is preferred herein that the plug of the applicator is a double-cylinder composed of an inner tube coaxially enclosed with an outer tube, wherein the slots or the flexible portions are formed in the outer tube.  
           [0031]    The plug in this case is designed such that only the outer tube is subjected to radial shrinkage. This structure will be advantageous in that the plug can be taken off the cylindrical body more lightly.  
           [0032]    Preferably, the plug may have on its outer periphery an airtight region, which will be kept in close contact with the inner periphery of the cylindrical body.  
           [0033]    Such an airtight region will prevent the ink or the like application liquid from leaking out through the plug, and thus protect the ink from drying up.  
           [0034]    The outer tube of the plug may have a further region formed at least in part integral with a plurality of annular ribs. This region is located on an outside of the airtight region.  
           [0035]    These ribs overlying one another and surrounding the outer tube are intended to protect the user&#39;s fingers from sliding over the outer periphery of plug.  
           [0036]    In an embodiment of the present invention, the applicator comprises a cylindrical body to be filled with a liquid for application, and a plug consisting of at least one of distal and proximal plugs, the plug detachably attached to an open end or ends of said body and exposed in part to the outside. Characteristically to this embodiment, the plug is composed of an outer tube and an inner tube disposed therein and has at least one longitudinal slot formed in the outer tube and extending axially of the cylindrical body, each slot being opened in the outer exposed face of the plug. Either the plug or the cylindrical body has a protrusion formed integral therewith and at a portion contacting the mating body or plug, and correspondingly, the cylindrical body or the plug has an engageable portion that is a lug or a recess facing such a protrusion. Each longitudinal slot extends over and beyond the protrusion or engageable portion such that the exposed part of the plug can be pinched centripetally to thereby cause elastic and temporary deformation of the plug so that an inner region of the plug in a pressed contact with the cylindrical body will be forced to reduce its overall radius of curvature to thereby enable and facilitate removal of the plug from this body. The plug in this embodiment has on its outer periphery an airtight region to be brought into a close contact with the inner periphery of the cylindrical body, when fitted therein.  
           [0037]    It is preferable in this embodiment that the number of the slots is at least two and each slot has an inner end continuing to an extension lying along the peripheral circumference of the outer tube.  
           [0038]    In this type of the applicator, each portion almost surrounded by the slots and extension is adjoined by a shortened boundary to the neighboring portion and is therefore easier to distort.  
           [0039]    Also preferably, each slot has an inner end continuing to extensions formed along the peripheral circumference of the outer tube, thereby assuming a T-shape as a whole.  
           [0040]    In another embodiment, the applicator comprises a cylindrical body to be filled with a liquid for application, and a plug consisting of at least one of distal and proximal plugs, the plug detachably attached to an open end or ends of said body and exposed in part to the outside. Characteristically to this embodiment, the plug is composed of an outer tube and an inner tube disposed therein and has at least two longitudinal slots formed in the outer tube and extending axially of the cylindrical body, wherein the at least two of the slots have outer ends closed and inner ends connected one to another by a tying slot. Either such a plug or the cylindrical body has a protrusion formed integral therewith and at a portion contacting the mating body or plug, and correspondingly, the cylindrical body or the plug has an engageable portion that is a lug or a recess facing such a protrusion. Each longitudinal slot extends over and beyond the protrusion or engageable portion such that the exposed part of the plug can be pinched centripetally to thereby cause elastic and temporary deformation of the plug so that an inner region of the plug in a pressed contact with the cylindrical body will be forced to reduce its overall radius of curvature to thereby enable and facilitate removal of the plug from this body. The plug in this embodiment also has on its outer periphery an airtight region to be brought into a close contact with the inner periphery of the cylindrical body, when fitted therein.  
           [0041]    It is desirable that the number of such longitudinal slots is an even number so that one or more pairs of them are provided, and the two slots forming one pair have the inner ends communicating one with another through the tying slot. These three slots constitute as a whole a generally U-shaped composite slot, which defines therein a tongue-shaped region.  
           [0042]    A basal outer end of such a tongue-shaped region will serve as a fulcrum-like support rendering this region more easy to elastically deform (viz., distort) itself.  
           [0043]    More preferably, the number of such longitudinal slots is four so that there are provided a first slot, a second slot, a third slot and a fourth slot. The first and second slots form a first pair, with the third and fourth slots forming a second pair. The two slots forming each pair have their inner ends communicating one with another through the tying slot. These three slots constitute as a whole a generally U-shaped composite slot, which defines therein a tongue-shaped region.  
           [0044]    The user will be able to lightly and readily disengage the plug from the cylindrical body of applicator, because he or she need to just pinch the plug at its two tongue-shaped regions that preferably face one another in a diametric direction. Although two pairs of such tongue-shaped regions facing one another may be provided (by forming eight slots), one pair of them suffice well for the plug to be manufactured as simply as possible. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0045]    [0045]FIG. 1 is an exploded perspective view of an applicator provided in a first embodiment of the present invention and shown partly in cross section, with an end closure (a proximal plug) having been separated from or not yet been fitted in a cylindrical body of the applicator;  
         [0046]    [0046]FIG. 2A is a front elevation of the applicator shown in FIG. 1;  
         [0047]    [0047]FIG. 2B is a plan view of the applicator shown in FIG. 1;  
         [0048]    [0048]FIG. 3A is a vertical cross section of the applicator shown in FIG. 1;  
         [0049]    [0049]FIG. 3B is a plan view of the applicator shown in FIG. 1;  
         [0050]    [0050]FIG. 4A is a front elevation of the end closure employed in the first embodiment shown in FIG. 1;  
         [0051]    [0051]FIG. 4B is a left-side elevation of the end closure;  
         [0052]    [0052]FIG. 4C is a top plan view of the end closure;  
         [0053]    [0053]FIG. 4D is a bottom plan view of the end closure;  
         [0054]    [0054]FIG. 4E is a cross section taken along the line A-A in FIG. 4C;  
         [0055]    [0055]FIG. 4F is a cross section taken along the line B-B in FIG. 4A;  
         [0056]    [0056]FIG. 5 is an enlarged cross section of a region around the end closure shown in use;  
         [0057]    [0057]FIG. 6 is a front elevation of the end closure employed in a second embodiment;  
         [0058]    [0058]FIG. 7 is a cross section of the end closure employed in a third embodiment, taken similarly to FIG. 4E;  
         [0059]    [0059]FIG. 8 is an exploded perspective view of the applicator in a fourth embodiment, with an end closure detached from a cylindrical body of the applicator;  
         [0060]    [0060]FIG. 9 is a perspective view of the end closure shown in FIG. 8 and seen at a different angle of view;  
         [0061]    [0061]FIG. 10 is a perspective view of the end closure shown in FIG. 8 and partly in cross section;  
         [0062]    [0062]FIG. 11A is a front elevation of the end closure employed in the fourth embodiment;  
         [0063]    [0063]FIG. 11B is a left-side elevation of the end closure shown in FIG. 11A;  
         [0064]    [0064]FIG. 11C is a top plan view of the end closure shown in FIG. 11A;  
         [0065]    [0065]FIG. 11D is a bottom plan view of the end closure shown in FIG. 11A;  
         [0066]    [0066]FIG. 1E is a cross section taken along the line A-A in FIG. 11D;  
         [0067]    [0067]FIG. 1F is a cross section taken along the line B-B in FIG. 11B;  
         [0068]    [0068]FIG. 12 is an exploded perspective view of the applicator in a fifth embodiment, with an end closure detached from a cylindrical body of the applicator;  
         [0069]    [0069]FIG. 13 is a perspective view of the end closure shown in FIG. 12 and seen at a different angle of view;  
         [0070]    [0070]FIG. 14 is a perspective view of the end closure shown in FIG. 12 and partly in cross section;  
         [0071]    [0071]FIG. 15A is a front elevation of the end closure in the fifth embodiment;  
         [0072]    [0072]FIG. 15B is a left-side elevation of the end closure of FIG. 15A;  
         [0073]    [0073]FIG. 15C is a top plan view of the end closure of FIG. 15A;  
         [0074]    [0074]FIG. 15D is a bottom plan view of the end closure of FIG. 15A;  
         [0075]    [0075]FIG. 15E is a cross section taken along the line A-A in FIG. 15D; and  
         [0076]    [0076]FIG. 15F is a cross section taken along the line B-B in FIG. 15A.  
         [0077]    [0077]FIG. 16 is a perspective view of an applicator provided in a sixth embodiment of the present invention and shown partly in cross section, with a distal plug having been separated from or not yet been fitted in a cylindrical body of the applicator;  
         [0078]    [0078]FIG. 17A is a front elevation of the distal plug employed in the sixth embodiment shown in FIG. 1;  
         [0079]    [0079]FIG. 17B is a left-side elevation of the distal plug;  
         [0080]    [0080]FIG. 17C is a top plan view of the distal plug;  
         [0081]    [0081]FIG. 17D is a cross section taken along the line A-A in FIG. 17C;  
         [0082]    [0082]FIG. 18 is an exploded perspective view of the applicator in a seventh embodiment, with an distal plug detached from a cylindrical body of the applicator;  
         [0083]    [0083]FIG. 19 is a perspective view of the distal plug shown in FIG. 18 and seen at a different angle of view;  
         [0084]    [0084]FIG. 20 is a perspective view of the distal plug shown in FIG. 18 and partly in cross section; and  
         [0085]    [0085]FIG. 21 is an exploded perspective fragmentary view of the applicator in a eighth embodiment, with a distal plug detached from a cylindrical body of the applicator. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0086]    Now some embodiments of the invention will be described, wherein the wordings ‘fore’ and ‘rear’ are meant to denote ends or portions of an applicator as to its posture in use. The end and region or portion including, facing or located adjacent to a penpoint are referred to as a fore end and a fore region or portion, respectively. The other end and region or portion on the side of the plug are likewise referred to as a rear end and a rear region or portion. The outer end of the end closure is thus a rear end thereof, and the inner end of the end closure is a fore end thereof.  
         [0087]    FIGS.  1  to  7  show an applicator  1  provided herein, in which its end closure  3  has slots  30 ,  31  or  50  whose open ends are located at the proximal end of said end closure. FIGS.  1  to  5  illustrate a first embodiment, and FIG. 6 is a scheme of a second embodiment, with FIG. 7 being a scheme of a third embodiment.  
         [0088]    The applicator  1  in these embodiments is a felt pen composed of a cylindrical body  2 , the end closure  3 , a penpoint tip  5  and an ink-occlusion column  6 . The cylindrical body  2  is an article molded of a polypropylene resin or the like to have opposite open ends. As seen best in FIG. 3A, the fore end portion of this body  2  gradually reduces its diameter, so as to provide a fore end opening  10 . The penpoint tip  5  that is fixed in a penpoint holder  11  retained in this end opening is formed of a material such as a cluster of bonded acrylic fiber bundles or the like. The ink as a liquid for application will migrate and transfer into this penpoint tip  5 , due to its capillary action.  
         [0089]    A rear end opening  12  of the cylindrical body  2  has the end closure  3  fitted therein. An annular groove  13  formed in the inner peripheryof said body  2  is located close to the rear end face thereof. As will be detailed below, a rib-shaped protrusion  36  of the end closure will engage with this annular groove  13 , which may be replaced with an annular rib-shaped lug or with a proper uncontinuous ridge or the like.  
         [0090]    The end closure  3  is a characteristic part in this embodiment, and will be described in detail. It is a double-cylinder composed of an outer tube  15  as the outer periphery of this closure  3  and an inner tube  16  formed to be coaxial with the outer tube. Inner diameter of said outer tube  15  is significantly larger than outer diameter of the inner tube  16 , such that an annular cavity is defined between them. A transverse and annular tying wall  20  (serving as an airtight region) is formed integral with fore portions of those tubes  15  and  16 , to be located near their fore ends. Thus, the outer and inner tubes are tightly adjoined one to another by such a thin annular transverse wall  20  that is merely about 1 mm thick in the longitudinal direction of this end closure.  
         [0091]    The inner tube  16  of the same length as the outer tube  15  has its fore end opened and its rear end  22  closed.  
         [0092]    On the other hand, both the fore and rear ends of the outer tube  15  are open. Such open ends of this tube are however not in a fluid communication with each other, because the annular transverse wall  20  intervenes between them.  
         [0093]    A flange  25  formed on and integral with the outer periphery of outer tube  15  is spaced about a third of its length from its rear end and is thus located rearwardly (upwardly in the drawings) of the annular tying wall  20 .  
         [0094]    Annular ribs formed also on the outer periphery and rearwardly of the flange  25  overlie one another in a stepped fashion. The inner (fore) region of said outer periphery of outer tube is located ahead the flange  25  and generally has a smooth surface, whose diameter is equal to the inner diameter of cylindrical body  2 .  
         [0095]    Two slots  30  and  31  are formed in the outer tube  15  to extend from its rear end and forwards across the flange  25 . The two longitudinal slots  30  and  31  having their rear ends opened are opposed diametrically to each other. Those slots are located symmetrical about the axis of outer tube  15 , so that they are spaced one from another an angle of 180 degrees.  
         [0096]    As will be seen in FIGS. 1 and 4A, the fore end (viz., inner end) of each of longitudinal slots  30  and  31  continues to a transverse cutout  35  of the same width as them. In detail, the fore end of each longitudinal slot joins the transverse cutout  35  at the middle point of the cutout  35 . This cutout formed also as a slot extends sideways in opposite directions from its middle point, such that it assumes a reversed T-shape together with the longitudinal slot.  
         [0097]    Two latching protrusions  36  each rib-shaped are formed on the outer periphery of outer tube  15 , at a position thereof slightly forwardly (downwardly in the drawings) of the flange  25 . Each latching protrusion  36  is an arc in plan view and extends an angle of about 90 degrees in the present embodiment. Also in this plan view, a line including both the centers of those protrusions  36  intersects a plane including both the longitudinal slots  30  and  31 . Therefore, in plan view of the outer tube  15 , those latching protrusions  36  are located at respective middle regions of two complementary sections  40  and  41  of said outer tube divided by the longitudinal slots.  
         [0098]    If the end closure  3  is viewed in a fore-and-aft direction, then it will be observed that those slots  30  and  31  extend from its rear end and beyond the latching ribs  36 .  
         [0099]    Cutouts  45  are formed in the fore end (lower end in the drawings) of the outer tube  15 , so as to avoid a negative pressure occurring in the ink-occlusion column  6 .  
         [0100]    As noted above, the end closure  3  fits in the rear end opening  12  of cylindrical body  2 , as shown in FIGS. 2A, 2B,  3 A and  3 B. In more detail, the closure&#39;s forward fixed portion  46  located ahead the flange  25  is inserted in the rear end opening  12  of the cylindrical body  2  so that the inner periphery thereof is kept in a pressed contact with the outer periphery of the outer tube of said portion. Thus, such a forward portion  46  serves in this embodiment as a fixed basal region in the closure, with this portions latching ribs  36  firmly engaging the cylindrical body&#39;s annular groove  13  to prevent the slipping off of said closure.  
         [0101]    A part of the closure&#39;s forward portion  46  will function also as an airtight region  47  in this embodiment. This is because the forward portion  46  has a substantially smooth periphery and its peripheral zone or region  47  interposed between the fore ends of slots  30  and  31  and the cutouts  45  has no indent or the like irregularity. The airtight region  47  thus kept in a close contact with the inner periphery of cylindrical body  2  over its full circumference will inhibit the ink to leak through this end closure  3 .  
         [0102]    As the applicator  1  is used many times, its ink will be consumed gradually. If and when the user feels the applicator scratchy to make his or her writing blurred, then he or she can detach the end closure  3  so as to refill the applicator with the ink.  
         [0103]    In the applicator  1  of this embodiment, its end closure  3  will be pinched at its exposed portion with his or her fingers to easily dismount it. The annular cavity  17  intervenes between the outer and inner tubes  15  and  16 , so that such a pinching of the exposed portion will cause the outer tube  15  to distort itself towards the cavity  17 . It is to be noted in this connection that the longitudinal slots 30  and  31  formed in the outer tube  15  divide it into the sections  40  and  41 , both being supported in a cantilevered fashion. Therefore, these sections are ready to make elastic deformation inwardly towards each other. In particular, the cutouts  35  extending transversely from the fore end of each longitudinal slot  30  and  31  are effective to lower secondary bending moment in cross section of the basal region of each section  40  and  41 . By virtue of this feature of the present embodiment, the sections will bend themselves at their basal ends to decrease the apparent overall diameter of the outer tube  15 .  
         [0104]    Also particularly in this embodiment, the slots  30  and  31  extend forwards beyond the rib-shaped protrusions  36 , so that the complementary sections  40  and  41  will bend themselves at their portions adjacent to the fore ends of slots. Distortion of these sections will cause inward and centripetal displacement of the rib-shaped protrusions  36 , thereby disengaging them from the annular groove  13  as indicated at the phantom lines in FIG. 5 and simultaneously weakening the pressure between the closure&#39;s forward fixed portion  46  and the cylindrical body  2 . Thus, the user can pull lightly the end closure  3  in its axial direction out of the cylinder to easily refill it with the ink.  
         [0105]    Although two longitudinal slots  30  and  31  are formed in the embodiment described above, the number of them may be changed if so desired. Those slots each having a constant width over their full length in this embodiment may be replaced with any other slot or slots whose width changes in axial direction of the end closure. FIG. 6 shows such an alternative example, viz., the second embodiment wherein a V-shaped slot  50  gradually decreases its width from its rear end. Other structural elements are the same as or similar to those in the first embodiment, and therefore description thereof will not be repeated. They will be indicated here simply with the same reference numerals as those in the preceding embodiment.  
         [0106]    The V-shaped slot  50  is advantageous in that the cantilevered sections  40  and  41  of the outer tube can be distorted in more distance at their rear end portions (upper portions in the drawings) than at their fore end portions. This means that the outer tube with such a V-shaped slot  50  in the end closure is much easier to reduce its temporary diameter.  
         [0107]    The slots  30  and  31  can be dispensed with, if the regions corresponding thereto in the outer tube are considerably thinned, or are formed with a softer material of a lesser modulus of elasticity, as compared with the remainder regions. Also in such a case, the outer tube will be ready to distortion to easily detach the end closure.  
         [0108]    In the preceding preferred embodiments, each longitudinal slot  30  and  31  continues to the transverse cutout  35  to facilitate elastic deformation of the outer tube sections  40  and  41 . The described advantages of the present invention will however be ensured well without aid of such cutouts, but requiring just a little stronger finger forceto deform the outer tube.  
         [0109]    The cutouts may preferably be deformed at the fore end of each longitudinal slot  30  and  31 . However they can be located intermediate between the fore and rear ends of slot, but desirably ahead the latching rib-shaped protrusions  36 .  
         [0110]    The end closure in the preceding embodiments is a double-cylinder composed of outer and inner tubes  15  and  16  of the same length. In a modification as the third embodiment of the invention shown in FIG. 7, these hollow tubes are of different lengths. It also is possible to make the inner tube not hollow but solid.  
         [0111]    The annular and transverse tying wall  20  connecting the outer tube  15  to the inner tube  16  is located near their fore ends in the foregoing embodiments. The wall  20  may however connect the rear ends of said tubes to each other.  
         [0112]    The embodiments described above employ the latching rib-shaped protrusions  36  formed on the end closure (proximal plug)  3  to fit in the recess formed in the cylindrical body  2 . This is for the purpose of more surely retaining the end closure in said body, but the invention will work well even if the closure or body were devoid of any such protrusions  36 .  
         [0113]    All the slots  30 ,  31  and  50  have open rear ends, though they may have no open ends in a case wherein the end closure has elongate and narrow holes as the slots located intermediate between its opposite ends.  
         [0114]    Next, a fourth embodiment will be described referring to FIGS.  8  to  11 F showing an end closure that has slots at its intermediate portions, peculiar to this case. Other structural elements are the same as or similar to those in the first to third embodiments. Therefore, they will not be so detailed but be simply indicated here at the same reference numerals as in the foregoing embodiments.  
         [0115]    An applicator  60  in the fourth embodiment is also a felt pen comprising the cylindrical body  2 , an end closure  61 , the penpoint tip  5  and the ink-occlusion column  6 . Three of these parts  2 ,  5  and  6  are of the same structure as those in the preceding embodiments.  
         [0116]    The end closure  61  is almost of the same structure as that in the first embodiments, except for its slots. This closure  61  is also a double cylinder composed of the outer and inner tubes  15  and  16  that are formed coaxial with each other and have between them an annular cavity  17 . The annular tying wall  20  having a thickness of about 1 mm connects the fore end portion of outer tube  15  to that of inner tube  16 .  
         [0117]    The inner tube  16  of the same length as the outer tube  15  is open at its fore end and closed at its rear end  22 , as is the case with the first embodiment. Both the fore and rear ends of the outer tube  15  are open ends, but are not in fluid communication with each other due to the presence of annular tying wall  20 .  
         [0118]    The outer configuration of the outer tube  15  resembles that in the preceding embodiments, since it has the flange  25  located at a third of length from its rear end and rearwardly (upwardly in the drawings) of the tying wall  20 .  
         [0119]    Also in this case, annular ribs are formed on the outer tube and behind (above in the drawings) the flange  25 , one above another. Fore region located ahead the flange is substantially smooth and has an outer diameter equal to inner diameter of the cylindrical body  2 .  
         [0120]    Thus, the end closure  61  shown in FIGS.  8  to  11 F is almost the same as that shown in FIGS.  1  to  5 , but significantly differs from it with respect to the shape of slots. The outer tube  15  of this closure  61  has four slots  62 ,  63 ,  64  and  65  formed intermediate between the fore and rear end faces of the closure  61  so as not to have any end exposed to the outside. Each slot  62  to  65  has a rear end located ahead the rear face of said closure, and extends forwards ahead the flange  25 .  
         [0121]    Two neighboring ones  63  and  64  of these slots are coupled to have their fore ends tied with a connection slot  66 , generally assuming as a whole a U-shape on the outer tube  15 . A generally U-shaped tongue-like region  67  thus formed in the outer tube  15  has three sides defined by the slots, with a basal end of this region integral with the body of this end closure. Another pair of slots  65  and  62  have also their fore ends tied with a further connection slot (as seen in FIG. 8) so as to define a similar tongue-like region  68 .  
         [0122]    The connection slots  66  extend along circumference of the outer tube, and thus perpendicularly to the longitudinal slots  62  to  66 .  
         [0123]    Two rib-shaped latching protrusions  36 , that are arc-shaped portions of the outer tube periphery, are located each ahead (below in the drawings) the flange  25 . One of the protrusions  36  is disposed in the tongue-shaped region  67  between the longitudinal slots  63  and  64  and close to the tying slot  66 . The other protrusion  36  is located in the other tongue-shaped region  68  between the further longitudinal slots  65  and  62  and likewise close to the other tying slot (as seen in FIG. 8). Similarly to the foregoing embodiments, cutouts or notches  45  are formed additionally in the fore end of the outer tube  15 .  
         [0124]    Also in the present embodiment, the end closure  61  fits in the rear end opening  12  of cylindrical body  2 . The latching ribs  36  formed in the closure&#39;s fixed basal region  46  firmly engages with the cylindrical body&#39;s annular groove  13  to prevent the slipping off of said closure  61 .  
         [0125]    When removing the end closure  61  from the applicator  60  of this embodiment, its exposed portion will be pinched for example with the user&#39;s fingers, similarly to the foregoing embodiments. Particularly in the present embodiment, the tongue-shaped regions  67  and  68  will be pressed inwards in radial direction. Since these regions are cantilevered and the annular cavity  17  is present between the outer and inner tubes  15  and  16 , each tongue-shaped region  67  and  68  will be lightly caused to make an inward elastic deformation as the outer tube  15  is deformed toward the cavity  17  when the exposed portion is pinched, i.e., the regions  67  and  68  are pressed inwards. It is a feature peculiar to and inherent in this embodiment that latching protrusions  36  are formed in the respective cantilevered tongue-shaped regions  67  and  68  and close to their free ends. Inward displacement of those protrusions  36  will thus take place an increased distance as compared with the foregoing embodiments, when the outer tube  15  is forced towards and into the annular cavity  17 . The latching protrusions  36  formed on the closure&#39;s forward fixed portion  46  will readily disengage from the annular groove  13 , so that the user can pull the end closure  61  off the cylindrical body very easily for the purpose of refilling it with the ink.  
         [0126]    The end closure in each embodiment described above has the flange  25  to apparently define three areas arranged in series on the outer periphery of lug, although such a flange can be dispensed with in the present invention.  
         [0127]    FIGS.  12  to  15 F illustrate the fifth embodiment wherein an end closure  70  has no such a flange.  
         [0128]    This end closure  70  lacks the flange, but is almost similar to the closure of the fourth embodiment shown in FIGS. 11A to  11 F. The end closure  70  in the fifth embodiment is composed of a larger-diameter region  71  and a smaller-diameter region  72 . A stepped portion or shoulder  73  interposed between these regions  71  and  72  serves as a flange, because it will bear against the face of open end of the cylindrical body  2  when the closure is inserted therein. The smaller-diameter region  72  located ahead the shoulder  73  fits in the rear opening  12  of the cylindrical body  2 , such that the outer periphery of this region  72  will function as the forward fixed portion  46  kept in a tight contact with the inner periphery of said body.  
         [0129]    Also in this end closure  70  of the fifth embodiment, its outer tube  15  has four slots  62 ,  63 ,  64  and  65 . Similarly to the fourth embodiment, these slots are formed intermediate between the fore and rear end faces of the outer tube  15  so as not to have any end exposed to the outside. Two neighboring ones  63  and  64  of these slots are coupled to have their fore ends tied with a connection slot  66 . One of the rib-shaped protrusions  36  is disposed in a generally U-shaped tongue-like region  67  having three sides defined by the slots  63 ,  64  and  66 . This protrusion  36  is positioned near the connection slot  66 . Another pair of slots  65  and  62  have also their fore ends tied with a further connection slot (as seen in FIG. 15A) so as to define a similar tongue-like region  68 . The other protrusion  36  is also positioned near the further connection slot  66 .  
         [0130]    The tongue-shaped regions  67  and  68  will be pressed inwardly and radially, when removing the end closure  70 . Elastic and smooth deformation of these regions will displace the rib-shaped protrusions  36  to disengage from the annular groove  13 .  
         [0131]    Although all the embodiments described above are directed to the end closure (proximal plug), the present invention can of course apply to a distal plug holding a penpoint tip.  
         [0132]    Exemplary distal plugs  75 ,  76 , and  77  are shown in FIGS. 16 through 17D,  18  through  20 , and  21 , respectively. The distal plug  75  is substantially similar to the end closure (proximal plug)  3  in the first embodiment shown in FIG. 1, except that the plug  75  has a penpoint tip holder  80  on its outer end remote from the cylindrical body  2 . Similarly, the distal plug  76  is substantially similar to the end closure 60  in the fourth embodiment shown in FIG. 8, except that the plug  76  has a penpoint tip holder  80  on its outer end remote from the cylindrical body  2 . As to the distal plugs  75  and  76 , other structural elements thereof that are the same as or similar to those of the end closures  3 ,  60  in the preceding embodiments will be indicated here simply with the same reference numerals as those in the preceding embodiment and description thereof will not be repeated.  
         [0133]    The distal plug  75  in the sixth embodiment, as shown in FIGS. 16 through 17D, has a penpoint tip holder  80 , which is on the outer end of the plug  75  remote from the cylindrical body  2 . As shown in FIG. 17D, the penpoint tip holder  80  has a cavity  83  in its inside. The holder  80  has an opening  81  on its distal end and an opening  85  on its proximal end. These openings  81  and  85  are in communication with each other through the cavity  83 . In other words, the distal plug  75  is generally cylindrical and has a throughhole on its central axis.  
         [0134]    A penpoint tip  82  is held by the penpoint tip holder  80 . The penpoint tip  82  is made of the same material that is described above with the penpoint tip  5 . The penpoint tip  82  is coaxial with the distal plug  75  and extends from the opening  81  through the cavity  83  to the opening  85 , protruding out of the plug  75  on both of the openings  81 ,  85 . As the distal plug  75  is attached to the cylindrical body  2 , the protrusion  86  of the tip  82  on the side of the opening  85  is in contact with an ink-occlusion column  6  within the cylindrical body  2  so as to allow ink to permeate from the ink-occlusion column  6  into the tip  82 .  
         [0135]    The distal plug  76  in the seventh embodiment, as shown in FIGS. 18 through 20, has a penpoint tip holder  80  that holds a penpoint tip  82 , similar to the distal plug  75  in the sixth embodiment.  
         [0136]    The distal plug  77  in the eighth embodiment, as shown in FIG. 21, is of a hollow cylindrical shape having openings on both of its ends and having a flange  87  near the middle of its axial length. The plug  77  also has a connecting portion  90  on its body adjacent to the flange  87 . The outer diameter of the connecting portion  90  is smaller than the outer diameter of the flange  87  and substantially equal to, or slightly smaller than, the inner diameter of the cylindrical body  2   a  at and in the vicinity of an opening  12  of the body  2   a . The connecting portion  90  has two annular ribs  88  formed on its outside, which protrude radially and extend circumferentially around the portion  90 .  
         [0137]    The distal plug  77  has slots  89 . The slots extend axially through the connecting portion  90  and across the flange  87 . The slots  89  extend radially through the distal plug  77  so that the inner space of the hollow plug  77  is in communication with the outer space of the plug  77  through the slots  89 .  
         [0138]    If the distal plug  77  is pinched centripetally so that the width of each slot decreases, the overall diameter of curvature of the plug  77  decreases. If the flange  87  of the plug  77  is pinched centripetally so that the width of each slot decreases, the overall diameter of curvature of the flange  87  decreases, resulting in the decrease of the overall diameter of the connecting portion  90  adjacent to the flange, thus facilitating removal of the distal plug  77 .  
         [0139]    To make up an applicator, the distal plug  77  holding the penpoint tip  82  therein is fitted in the cylindrical body  2   a . As the outer diameter of the portion  90  is substantially equal to, or slightly smaller than, the inner diameter of the cylindrical body  2   a  at and in the vicinity of an opening  12  of the body, and as the ribs  88  facilitate close contact of the plug with the inner surface of the opening  12 , the plug  77  is fastened to the cylindrical body  2   a . It is to be noted that the cylindrical body  2   a  in this embodiment has no annular groove  13 , which is formed in the cylindrical body  2  employed in each of the first to seventh embodiments.  
         [0140]    The applicator in each of the sixth to eighth embodiments also facilitates refill of ink. It is to be noted that the invention is applicable to a so-called “twin-type” applicator that has two penpoints on both end of the cylindrical body and has no proximal plug. Two detachable distal plugs may be provided on the “twin-type” applicator.  
         [0141]    Applicators that enables refill of ink by detaching either of the distal and proximal plugs at user&#39;s discretion can also be manufactured.  
         [0142]    It will now be apparent that the plug exemplified as the proximal or distal plug is ready to elastic distortion to reduce its temporary diameter, enabling an easy detachment thereof from the cylindrical body of applicator.  
         [0143]    The foregoing disclosure of specific embodiments is intended to be illustrative of the broad concepts comprehended by the invention. It is to be understood that the invention is not limited to the specific embodiments except as defined in the claims.