Abstract:
A liquid marker system utilizes three primary components to permit marking of lines of various widths from a single nib. The three components are a porous nib, a transfer wick and a squeezable container. Operation relies on different squeeze pressures applied to the housing to produce different line widths from the single nib as the nib is moved across a marked surface. The porous wick provides a resistance to flow until the bottle is squeezed and then supplies a minimum of capillary flow to the nib. The user squeezes the container to overcome the resistance of the wick. No venting of the container interior is required because the wick and nib system allows the passage of air into the container when the container is returned to its unstressed (i.e., un-squeezed) condition.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 09/951,526, filed Sep. 14, 2001 and entitled “Pressure Modulated Free Ink Marker For Producing Variable Line Width” which application claims priority from U.S. Provisional Patent Application Ser. No. 60/185,159, entitled “Pressure Modulated Free Ink Marker For Producing Variable Line Width” and filed Feb. 9, 2000. The disclosures of both applications are incorporated herein by reference in their entireties. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Technical Field  
           [0003]    The present invention pertains to improvements in liquid markers and more particularly, to free ink marker systems and methods utilizing pigments, paints, dyes, liquid chalk, etc.  
           [0004]    2. Discussion of the Art  
           [0005]    Various prior art markers permit marking fluids to be squeezed from a container through a porous nib; however, such markers have lacked the ability to control or modulate the delivery rate as required for detailed drawing, calligraphy, and other detail oriented applications. Moreover, squeeze containers are typically subject to leakage due to pressure variations and temperature changes. Other prior art marker designs utilize ink housed in absorbent fibers and transferred by capillary action to a porous nib.  
           [0006]    Conventional liquid markers can only effect differing line widths by using a differently sized and/or configured nibs for each desired line.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0007]    It is an object of the invention to provide a liquid marker delivery method and apparatus in which the marker liquid can be squeezed from a container in a manner that permits close control over the delivery rate of the liquid.  
           [0008]    It is another object of the invention to provide a liquid marker delivery method and apparatus capable of producing different line widths and effects with a single nib.  
           [0009]    The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.  
           [0010]    In accordance with the present invention, a marker system utilizes three primary components to permit the marker to produce lines of various widths from a single nib. The three primary components are a porous nib, a transfer wick and a squeezable container or housing in which the wick and nib are disposed with the nib protruding from one end thereof. Stated otherwise, the present invention combines a porous wick utilized in conjunction with a squeezable plastic tube or bottle and a porous plastic or felt nib. System operation relies on different squeeze pressures applied to the housing to produce different line widths from the single nib. Squeeze bottles without a wick are subject to leakage due to pressure variations and temperature changes. The porous wick of the present invention provides a resistance to flow until the bottle is squeezed and then supplies a minimum of capillary flow to the nib. The user squeezes the container to overcome the resistance of the wick, and can supply marker fluid to the nib at volumes directly related to the squeeze pressure. As used herein the terms “wick” and “wick member” refer to a device capable of drawing liquid along surfaces thereof (i.e., by virtue of the very nature of its material and the nature of the liquid), or through one or more capillary orifices defined through the member, to provide the liquid delivery requirements described herein.  
           [0011]    The simple device of the present invention requires no venting to atmosphere of the container interior because the wick and nib system allows the passage of air into the container. Specifically, when the container is returned to its unstressed (i.e., unsqueezed) condition, ambient air is aspirated back into the container through the nibwick system.  
           [0012]    The squeeze pressure required to emit marker fluid from the container interior is set to be greater than any atmospheric differential pressure that would normally be experienced in the use of the marker system. In this manner, the marker system operates properly in airplanes, at different ground elevations, etc., without leaking due to pressure differentials.  
           [0013]    The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following definitions, descriptions and descriptive figures of specific embodiments thereof wherein like reference numerals in the various figures are utilized to designate like components. While these descriptions go into specific details of the invention, it should be understood that variations may and do exist and would be apparent to those skilled in the art based on the descriptions herein.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is an exploded view in perspective of a preferred embodiment of the marker system of the present invention.  
         [0015]    [0015]FIG. 2 is a view in longitudinal section of the embodiment of FIG. 1.  
         [0016]    [0016]FIG. 3 is a view in longitudinal section of a modified version of the embodiment of FIG. 1.  
         [0017]    [0017]FIG. 4 is a view in perspective and longitudinal section of the embodiment of FIG. 1 shown during the delivery of marker fluid.  
         [0018]    [0018]FIG. 5 is a view in perspective and longitudinal section of the embodiment of FIG. 1 shown immediately following the delivery of marker fluid.  
         [0019]    [0019]FIG. 6 is an exploded view in perspective of the distal end portion of another marker of the present invention incorporating a modified nib with a channel defined therein.  
         [0020]    [0020]FIG. 7 a  is a view in transverse section of the nib employed in the embodiment of FIG. 7.  
         [0021]    [0021]FIG. 7 b  is a view in transverse section of a nib having plural channels defined therein.  
         [0022]    [0022]FIG. 8 is a view in perspective of the distal end portion of another marker of the present invention incorporating a channel in the housing portion surrounding the nib.  
         [0023]    [0023]FIG. 9 is a side view in elevation of another marker embodiment of the present invention in which the housing is widened to facilitate control of fluid outflow.  
         [0024]    [0024]FIG. 10 is a side view in elevation of another marker embodiment of the present invention in which the housing is a squeeze bottle.  
         [0025]    [0025]FIG. 11 is a side view in elevation of another marker embodiment of the present invention in which the housing is a squeeze bottle having flattened sides.  
         [0026]    [0026]FIG. 12 is a side view in elevation of another marker embodiment of the present invention in which the housing is in the form of a pocket pen having a squeeze button actuator to control marker fluid outflow.  
         [0027]    [0027]FIG. 13 is an exploded side view of another marker embodiment of the present invention in which the wicking function is provided by a capillary orifice extending through the wick member.  
         [0028]    [0028]FIG. 14 is a side view in longitudinal section of the wick member used in the embodiment of FIG. 13.  
         [0029]    [0029]FIG. 15 is a top view in plan of the wick member of FIG. 14.  
         [0030]    [0030]FIG. 16 is a top view in plan of a modified wick member having plural capillary orifices.  
         [0031]    [0031]FIG. 17 is a side view in elevation of a modified end piece according to another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]    Referring to FIGS. 1 and 2, a marker system constructed in accordance with the present invention includes a housing comprising a hollow barrel  10  having an externally threaded distal end  20  to which an internally threaded end piece  11  is threadedly engaged. The interior of end piece  11  is hollow and communicates with the hollow interior of barrel  10 . Projecting from the forward end of end piece  11  is a porous nib  15 , the rearward portion of which extends into the hollow interior of end piece  11 . Nib  15  is made of conventional porous material of the type typically used in marker devices and is configured as a solid cylinder with a tapered distal tip. The taper is preferably gradual such that the tip appears more parabolic than conical.  
         [0033]    A generally cylindrical fibrous filler member or transfer wick  12  is disposed within the housing with its leading end preferably in contact with the rearward end of nib  15 . A mixing slug or agitator  14  may optionally be disposed within the housing to facilitate mixing of marker fluid disposed in the reservoir formed by the housing. Specifically, shaking the housing causes slug  14  to mix the fluid in the reservoir.  
         [0034]    A removable cap  13  can be secured by friction fit over the end piece  11  to cover nib  15  when the unit is not in use. Removal of cap  13  exposes the nib  15 . As illustrated in FIG. 3, a helical spring may be disposed between the rearward end of transfer wick  12  and the interior surface of the proximal end wall of barrel  10  to urge the wick into biased longitudinal engagement with the rearward end of nib  15 .  
         [0035]    As best illustrated in FIG. 4, with cap  13  removed, marker liquid may be forced out of the housing by squeezing the resilient sidewall of barrel  10  radially inward until the pressure created in the internal reservoir exceeds ambient atmospheric pressure at the exposed forward end of nib  15 . Liquid disposed in and about wick  12  is forced through the porous nib and out through the forward end of end piece  11  onto a surface, such as a sheet of paper, at a flow rate dependent upon the applied pressure. This applied pressure, and hence the resulting flow rate of the marker liquid, determines the width of the line made by the nib as it traverses the marked surface. That is, the amount of liquid deposited at any point on the marked surface depends upon the speed of movement of the nib across the marked surface and the squeeze pressure induced flow rate of the liquid. The applied finger pressure on barrel  10  distorts the transfer wick  12  to the degree necessary to force liquid therefrom into and through the porous nib  15 .  
         [0036]    The porous transfer wick  12  provides resistance to flow until the barrel  10  is squeezed and then supplies a minimum of capillary flow to the nib. The user squeezes the barrel to overcome the resistance of the wick, permitting supply of marker fluid to the nib at volumes and flow rates directly related to the squeeze pressure.  
         [0037]    As illustrated in FIG. 5, upon release of the finger pressure on barrel  10 , a negative pressure (relative to the ambient atmosphere) is created within the reservoir as the barrel wall resiliently returns to its unstressed state. This negative pressure draws ambient air into the reservoir along with liquid disposed on and in the porous nib  15 . Accordingly, marker fluid on or in the nib is drawn by suction back into the reservoir, thereby preventing leakage of the marker fluid after the finger pressure is removed from the barrel.  
         [0038]    In order to aid in aspiration of ambient air upon release of finger pressure, it is desirable in some embodiments of the invention to provide a channel defined longitudinally along the nib periphery. One such embodiment is illustrated in FIGS. 6, 7 a  and  7   b.  Nib  25  is seen to have a shallow channel  26  extending longitudinally along the cylindrical portion of the nib, stopping short of the tapered distal tip. Channel  26  conducts ambient air into the reservoir when a negative pressure (relative to ambient) is created therein when the squeezing force is removed from the barrel. If desired, a plurality of longitudinal channels  26  may be defined in the nib periphery as illustrated in FIG. 7 b.    
         [0039]    It is also possible to provide the aspiration-assisting channels in the housing portion engaging the nib rather than in the nib itself. An example of this may be seen in the embodiment of FIG. 8 wherein a longitudinally extending channel  27  is defined in the interior surface of end piece  11 .  
         [0040]    Referring to FIG. 9, the squeezable barrel  10  may be configured with an outwardly convex bulge  30  to provide a greater range of squeeze distance and more control over the delivery of marker liquid. The “barrel” may also take the form of a smaller cylindrical or slightly frusto-conical squeeze bottle (FIG. 10), or a generally circular or elliptical squeeze bottle having flat sides (FIG. 11). Alternatively, the barrel may have only a localized squeezable area, or squeezable button to pressurize the barrel interior as shown in FIG. 12.  
         [0041]    The wick member  12  in the embodiment of FIG. 1 is made from materials commonly used for this purpose, such as felt, porous thermoplastic material, fibrous material, etc. The material, by its nature, “wicks” or draws the marker liquid by capillary action along the material surface to the nib. The wicking function is well known and is described, for example, in U.S. Pat. No. 3,972,629 (Whalen), the entire disclosure of which is incorporated herein by reference. For purposes of the present invention, and as illustrated in FIGS. 13 through 16, the wicking function may also be effected by providing one or more narrow orifices or capillaries extending longitudinally through a “wicking” member. The orifices serve the wicking function due to the surface tension on the liquid created in the narrow orifice. The wicking member  32  shown in FIGS.  13 - 15  is made of any suitable material that is not itself “wicking” and is provided with a narrow capillary orifice  33  defined longitudinally therethrough. Member  32  is substantially shorter than wick  12 , and functions in response to pressurization of the interior of barrel  10  by conducting liquid to the nib  15 . Member  32  is retained in end piece  11  proximally (i.e., immediately rearward) of nib. The distal end of member  32  abuts the proximal end of nib  15  at the egress end of orifice  33 , whereby the “wicked” liquid is directed into the porous nib. As shown in FIG. 16, wicking member may be provided with a plurality of capillary orifices.  
         [0042]    A further possible modification of the present invention is to provide a slightly enlarged diameter section in the forward or downstream end of the nib-retaining bore defined in the end piece or nib holder  11  as, for example, illustrated in FIG. 17. The resulting narrow annular space  40  surrounding the forward end of the nib  15  serves a number of functions. First, instead of or in conjunction with the channels  26 ,  27  described above, the annular space  40  aids in aspiration of air into the marker fluid reservoir if a lower than ambient pressure is created in the barrel after the squeezing force is removed. In addition, if a lower than ambient pressure is created immediately surrounding the forward end of the nib (as, for example, when the cap is quickly removed), the annular space  40  functions as a mini-reservoir to receive marker fluid from the nib to prevent the fluid from exploding outwardly. The annular space is sufficiently small to permit marker fluid to be retained therein by surface tension rather than dripping along the nib. The annular space typically occupies one-third to one-half of the length of the nib-retaining bore, but may be longer or shorter to meet the requirements of different applications. The diameter of the annular space depends partly on the diameter of the nib and is typically five to twenty-five percent of the nib diameter.  
         [0043]    The marker system described is applicable to all sorts of liquid pigments, paints, dyes, liquid chalks, etc., so that it can be used for a variety of applications, including lettering, painting, drawing, calligraphy, etc. The invention is the utmost in simplicity in requiring only three basic elements, namely the porous nib, the transfer wick and the squeezable reservoir. The reservoir may be in the form of a marker device as shown, a bottle, or any other form and shape consistent with the end use of the device.  
         [0044]    The invention is highly advantageous in that it operates in an on/off manner with regard to liquid flow so that there is no dripping or spillage, no matter the orientation of the marker.  
         [0045]    It should be understood that the principles of the present invention are adaptable for use with selective pressurization means other than a squeezable barrel. For example, selective pressurization of the marker fluid reservoir can be effected by the user blowing through a suitable mouthpiece provided in the manner described and illustrated in U.S. Pat. No. 5,687,886 (Bolton) the entire disclosure of which is incorporated herein by reference. Specifically, according to the disclosure in the Bolton patent a hollow tubular housing contains a fluid reservoir a projecting nib. The apparatus has at its end remote from the nib a mouth piece through which air can be blown into the housing. The mouthpiece may be releasably secured to the housing and its position on the housing may be varied to accommodate markers of different length. Alternatively, the mouthpiece may be formed integrally with the housing.  
         [0046]    Having described preferred embodiments of new and improved liquid marker delivery method and apparatus, it is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the teachings set forth herein. It is therefore to be understood that all such variations, modifications and changes are believed to fall within the scope of the present invention as defined by the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.