Abstract:
A pen or other writing instrument has a cap with a bulb that is relatively heavy compared to the barrel of the pen and has a larger diameter. The bulb has an approximately oval outer shape and may include a tube for receiving the pen or an outer ring. When placed or tossed onto a desk or table, the cap causes the pen to remain standing, where it is easily located. The cap can be formed as a single piece.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part of U.S. patent application Ser. No. 09/080,337, filed May 15, 1998, now abandon. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to writing instruments and, more particularly, to caps for pens and other writing instruments. 
     BACKGROUND OF THE INVENTION 
     A typical pen has a barrel that surrounds an ink cartridge and a cap that covers the point of the pen. When closed, the pen has an approximately cylindrical shape. 
     When a user finishes with the pen, it may be placed in a desk drawer or, commonly, tossed onto the top of a desk. While various stands and holders exist for pens, those tend to be large and to be pre-positioned on one part of a desk. Although movable, they are not always conveniently located when a user is finished using the pen. 
     When placed on a desk, a pen has little height and is easily lost among the papers and files already on the desk. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a pen or other writing instrument is provided with a cap with a bulb at the end that is relatively heavy compared to the barrel of the pen. When placed or tossed onto a desk or table, the bulb causes the pen to remain standing, where it is easily located. 
     The bulb may be formed integrally with the cap or as a separate piece. The cap can be sold with the pen, in place of a conventional cap, or as a replacement cap for a pen. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective side view of a pen according to a first embodiment of the present invention. 
     FIG. 2 is a side elevational view of a pen according to the first embodiment of the present invention. 
     FIG. 3 is a perspective side view of a pen according to the first embodiment of the present invention with the cap separated from the pen. 
     FIG. 4 is a partially cut-away, partially exploded side elevational view of a pen according to the first embodiment of the present invention. 
     FIG. 5 is a perspective side view of a pen according to a second embodiment of the present invention. 
     FIG. 6 is a side elevational view of a pen according to the second embodiment of the present invention. 
     FIG. 7 is a perspective side view of a pen according to the second embodiment of the present invention with the cap separated from the pen. 
     FIG. 8 is a partially cross-sectional side elevational view of a pen according to the second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIGS. 1-4, which show a first embodiment of the present invention, pen  10  includes barrel  12 , cartridge  16 , and cap  20 . When closed, pen  10  is approximately 5 inches long. However, the size of the pen can be modified for appearance and as appropriate for the materials used to make the pen. 
     Barrel  12  is formed from a styrene-based resin or plastic, and is a hollow tube that is closed at back end  30  and open at front end  34 . Preferably, barrel  12  is widest at front end  34  and tapers toward back end  30 . In a preferred embodiment, barrel  12  is approximately 9 millimeters wide at front end  34  and approximately 8.2 millimeters wide at back end  30 . Other shapes for barrel  12  may also be used. 
     Front end  34  of barrel  12  is threaded internally to receive cartridge  16 . Alternatively, barrel  12  can include a separate ring that is inserted into front end  34  of barrel  12 , with the ring having internal threads to receive cartridge  16 . 
     Cartridge  16  includes a reservoir holder  42 , which holds an ink reservoir (not shown) and a writing portion, which includes point or nib  46 . Preferably, reservoir holder  42  is made from plated brass and cartridge  16  is for a ballpoint or rollerball type pen. Alternatively, a fountain pen can be used. Reservoir holder  42  is threaded on its outside to permit it to be screwed into front end  34  of barrel  12 . In a preferred embodiment, reservoir holder  42  is approximately 17 millimeters long and approximately 9 millimeters in diameter. 
     Cap  20  has a back (frist) end an a front (second) end, and includes hollow tube  50  and solid bulb  52 . Tube  50  has an opening at the back (first) end  60  with a first diameter and is connected to bulb  52  at the front (second) end, opposite the back (first) end. Bulb  52 , having a second diameter, is connected to the front (second) end of the tube  50  at an instrument (third) end and has an approximately oval front side at a bottom (fourth) end, opposite the instrument (third) end. In one embodiment, tube  50  and bulb  52  are formed from a single piece of brass or lead-based brass. Alternatively, tube  50  and bulb  52  are formed from separate materials, such as lead-based brass for bulb  52  and aluminum or an aluminum or other metal-lined plastic for tube  50 . Where, for example, tube  50  is made from metal, the inner portion of tube  50  may be threaded to fit threads at the end of a cylindrical sheath, which is formed from plastic and fits within tube  50 . Tube  50  is tapered at its front, toward bulb  52 . Where tube  50  and bulb  52  are formed from separate materials, the plastic inner portion  18  of tube  50  (or its internal sheath) extends beyond the metal outer portion  56  and is threaded for insertion of tube  50  into bulb  52 . Cartridge  16  fits against the plastic inner portion  18  of tube  50  to close pen  10 . When closed, cartridge  16  is held firmly by plastic inner portion  18 , but cartridge  16  can be pulled from tube  50  to open pen  10 . Alternatively, cartridge  16  can be screwed to tube  50 . In a preferred embodiment, cap  20  is approximately 35-40 millimeters long, and tube  50  is approximately 27 millimeters long and 9 millimeters in diameter before the tapering. Bulb  52  is approximately 24 millimeters in diameter at its widest point. Alternatively, bulb  52  can have a larger or smaller diameter relative to the diameter of tube  50 , and typically will be at least twice the diameter of tube  50 . Generally, a larger diameter for bulb  52  will increase the angle for which pen  10  will remain standing. 
     When pen  10  is closed, the open end  60  of tube  50  meets the front end  34  of barrel  12 . 
     Bulb  52  is sufficiently large that most of the weight of pen  10  is in bulb  52 . 
     When pen  10  is placed on a flat surface at close to a vertical position, such as small angles of up to at least 10-15 degrees from vertical, the weight of bulb  52  forces pen  10  into a standing (vertical) position. Preferably, when cap  20  is placed on a flat surface at any angle it will stand, even if initially placed horizontally. Similarly, it is preferred that pen  10  will remain standing if placed on a flat surface at any angle. From the front, as can be seen in FIG. 1, bulb  52  has an approximately round shape. From the side, as shown in FIGS. 2 and 4, the outer side  62  of bulb  52  has an approximately oval shape. 
     FIGS. 5-8 show a second embodiment of the invention described above. Characteristics that are the same as with the above embodiment generally are not repeated. Pen  110  includes barrel  112 , cartridge  116 , and cap  120 . Extending from barrel  112  is tip  146 . In a preferred embodiment, barrel  112  is approximately 102 mm long, and tip  146  extends approximately 15 mm from the open end  134  of barrel  112 . Otherwise, barrel  112 , cartridge  116 , and tip  146  are similar to the barrel, cartridge, and tip described above. Like the above embodiment, the size can be modified for appearance and as appropriate for the materials used to make the pen. 
     Cap  120  includes bulb  152 , which is encircled by outer ring  160 . Preferably bulb  152  and outer ring  160  are formed from a single piece of brass or lead-based brass. Outer ring  160  adds additional mass to cap  120 , to improve the ability of pen  110  to remain standing when placed on a flat surface at close to a vertical position. Alternatively, bulb  152  and outer ring  160  could be formed from two pieces or from separate materials. Bulb  152  preferably has a height of approximately 24 mm. 
     In a preferred embodiment, outer ring  160  has a diameter of approximately 38 mm at its widest, and angles inward to bulb  152 . Although shown ending approximately in a point, outer ring  160  could end in a curve, and the straight angles inward also could be replaced with curves. 
     Above outer ring  160 , bulb  152  has a diameter at upper junction  162  of approximately 27.5 mm and curves up to top  164  with a generally bulbous shape. The distance from upper junction  162  to the top  164  of bulb  152  is preferably approximately 9 mm. Although top  164  preferably is flat, the portion of bulb  152  above outer ring  160  could define a continuous curve. 
     Below outer ring  160 , bulb  152  has a diameter at lower junction  166  of approximately 30 mm and curves down to bottom  168 , in a generally oval shape. The distance from lower junction  166  to the bottom  168  of bulb  152  is approximately 8.5 mm. 
     At the top  164  of bulb  152  is drilled a chamber  170 , for receiving tip  146 . Although chamber  170  preferably is drilled vertically into bulb  152 , chamber  170  could, alternatively, extend at an angle into bulb  152 . Approximately 1.5 mm from the top of chamber  170  is a recess  174 , into which is inserted and affixed a rubber O-ring  178 . In a preferred embodiment, O-ring  178  has an outer diameter of 9.5 mm and an inner diameter of 6 mm. O-ring  178  holds tip  146  snugly in cap  120  at crevice  114 , from which tip  146  can be removed when pen  110  is to be used. When pen  110  is closed, front end  134  of barrel  112  contacts top  164  of bulb  152 . 
     As with the prior embodiment, when pen  110  is placed on a flat surface at close to a vertical position, such as small angles up to at least 10-15 degrees from vertical, the weights and positions of bulb  152  and outer ring  160  force pen  110  into a standing (vertical) position. Preferably, when cap  120  is placed on a flat surface at any angle it will stand, even if initially placed nearly horizontally. Similarly, it is preferred that pen  110  will remain standing if placed on a flat surface at any angle. 
     Although the preferred embodiments have been described in terms of a pen, the cap can be used with other writing instruments. Also, the cap can be used with other objects that would otherwise lie relatively flat. The internal plastic lining  18  of tube  50  from the first embodiment can have any appropriate inside shape. Alternatively, lining  18  can be omitted, and the inside of tube  50  shaped to fit a cylindrical or other long and thin object to be inserted into cap  20 . 
     While there have been shown and described examples of the present invention, it will be readily apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims. Accordingly, the invention is limited only by the following claims and equivalents thereto.