Abstract:
This invention provides a capless retractable writing tool applicable to neutral and volatile writing fluids and capable of self sealing and substantially preventing vapor fluid from evaporating through the valve when the tip is in the retracted position. The valve includes a front end and a back end, where the front end is adapted to open to allow the writing tip to extend there through. The front end of the valve may have a concave shape profile with a slit. To assist in closure of the slit and to increase the amount of vapor pressure the slit can withstand, a tension device may be provided around the front end to substantially seal the slit when the tip is within the valve. The back end of the seal has a hole adapted to seal around a cartridge that the tip is attached to. When the writing tool is in the retracted position, the tip is between the front and back ends to substantially seal the tip from the outside air and prevent the release of vapor fluid from within the valve. The valve may be fabricated of a material that is impermeable to air and vapor fluid.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is in the field of retractable writing tools, and more particularly, to writing tools that employ volatile inks that evaporate when exposed to air. Still more particularly, the present invention relates to writing tools having a self sealing valve that seals the writing tip from outside air and prevents the release of vapor fluid from within the valve. The self sealing valve also allows the writing tip to be protracted through the valve, and retracted back into the valve.  
         [0002]     Existing writing tools that use volatile fluids include a cartridge that holds the fluid supply and secures the writing tip, and a cap that protects the fluids from evaporating. In use the cap is removed from the cartridge and stored on the back end of the writing tool. Hence, existing writing tools that use volatile fluids generally require two free hands to operate and tightly sealing caps to minimize the writing tips exposure to air. Failure to replace the cap tightly from this type of dispenser causes the fluid to evaporate, and dry up the fluid after a short time. To open and store the cap requires two free hands, one to remove the cap and the second to hold the body securely. The use of two free hands to remove the cap from the body may be undesirable to the user if they only have one free hand.  
         [0003]     Many writing tools fall into two categories: a retractable type and a non-retractable type. The distinction between these two types of writing tools usually depends on the type of fluid that is used. The fluid in the retractable type has a low evaporation rate so that even though the tip is exposed to the air, the writing tip will not dry out. In contrast, the fluid in the non-retracting type has a higher evaporation rate than the fluid in the retractable type so that the fluid can evaporate through the tip and into the air. This can cause the tip in the non-retractable type to dry out. Thus, a cap is needed to seal the tip of the non-retractable writing instrument from the air.  
         [0004]     A ballpoint pen is a good example of a retractable writing tool that includes an internal mechanisms to allow the tip to move back and forth inside the front cowling of the pen. Retractable writing tools are convenient to use because with one hand, a user can press and release the plunger back and forth to cause the tip to move back and forth. Once the tip is in the retracted position, the tip is protected from accidentally drop and cannot accidentally write onto a surface.  
         [0005]     A permanent marker is a good example of a non-retractable writing instrument that needs a cap to seal the tip from outside air. If the cap is left off the marker, lost or not secured properly, the tip would eventually dry out. This can shorten the life of the marker. As such, users have to remember to put the cap back on after each use. For users, however, remembering to put the cap back on after each use can be inconvenient and inefficient. Besides being inconvenient and inefficient, misplaced caps can be a choking hazard for small children.  
         [0006]     To eliminate the need for a cap, others have designed a writing tool with a retractable tip that is sealed from the outside air when in the retracted position. The tip is sealed by incorporating some type of a sealing cover around the tip that opens to allow the tip to move in and out of the sealing cover. These sealing covers however, are complex and fail to seal the tip from outside air. In addition, the sealing covers fail to eliminate the loss of vapor fluid that is built up within the sealing covers from escaping through the openings when the writing tip is retracted back into the sealing covers. The sealing covers are also made of materials that are permeable so that vapor fluid can escape through the walls of the sealing covers as well.  
         [0007]     In addition to the problem with the tip being exposed to air and vapor fluid escaping through the openings of the sealing cover, current retractable writing tool designs with sealing covers use permeable materials in the fabrication of the sealing covers. Accordingly, there is a need for a retractable writing tool that can seal the tip in the retracted position from outside air and the loss of vapor fluid that is built up within the sealing cover when the writing tool is in the retracted position.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008]     The present invention is intended to provide a capless writing tool applicable to neutral and volatile writing fluids and capable of self-sealing and substantially preventing vapor fluid from evaporating through the valve when the tip is in the retracted position. The present invention includes a front cowling with an opening to allow the tip to move in and out of the opening. Adjacent to the front opening and within the front cowling is a valve that substantially seals the tip from outside air, and prevents the release of vapor pressure from within the valve when the tip is in a retracted position. The writing instrument also includes a back body with a back opening. Disposed within the back opening is a plunger that is adapted to move back and forth axially. When the plunger is forced into the back body cavity, there is provided a mechanism for locking the tip against the urging force of a compression spring so as to hold the tip in the writing state, the mechanism unlocks the tip when the plunger is forced further into the back body cavity and the tip is retracted back into the valve for storage. The valve includes a front end and a back end, where the front end is adapted to open to allow the tip to extend there through. To open the front end may have a concave configuration or profile with a slit. The slit can be cut or formed into the valve. The front end of the valve may have a groove formed along the elongated axis. The groove may have a thin layer of material between the inner and outer wall of the front end of the valve, the groove is pierced and forms a slit when the tip of the writing tool is forced through it by pushing down on the plunger at the back of the barrel and protracting the tip of the writing tool. The front end may have a planner or convex configuration or profile with an elongated axis. To enhance proper closure of the slit and to increase the amount of vapor pressure the slit can withstand, a tension device may be provided around the front end to substantially seal the slit when the tip is in the retracted position. An array of ribs along the outer or inner circumference of the front end of the valve will also enhance proper closure of the slit. In addition, the inner circumference of the front cowling may be about the same or slightly less than the circumference around the front end of the valve to support the closure of the slit. The back end of the valve has a hole adapted to substantially seal around the cartridge that the tip is attached to. To increase the amount of vapor pressure the back end of the valve can withstand, the interference fit between the hole and cartridge can be increased. In the retracted position, the tip is between the front and back ends of the valve to substantially seal the tip from the outside air, and to prevent the release of vapor pressure from within the valve, thereby eliminating the need for a cap.  
         [0009]     With capped writing tools the vapor fluid from within the reservoir will evaporate through the writing tip and into the enclosure of the cap. Some of the molecules from the vapor fluid will be reabsorbed by the tip and feeder and return to a fluid state. Some of the molecules that make up the vapor fluid will condense within the enclosure of the cap until equilibrium is reached and the enclosure is saturated. The pressure within the enclosure when saturated in a capped writing tool can range from 0 to 4 pounds per square inch. If the capped writing tool is not sealed to withstand a pressure level of 0 to 4 pounds per square inch, the vapor fluid from within the reservoir will evaporate into the atmosphere. If the material used to fabricate the cap is permeable, the vapor fluid will pass through the material and into the atmosphere.  
         [0010]     To solve the above mentioned problem, a capless writing tool is provided comprising a valve having a front end and a back end that substantially seals the tip from outside air, and prevents the release of vapor pressure from within the valve when the tip is in a retracted position. The valve for the present invention may be made from a material that is impermeable to outside air and vapor fluid. The valve may be treated by a secondary process known as fluorination, whereby the valve is introduced to the element fluorine to further reduce or eliminate permeation of the vapor fluid. The valve may be made of a material that is durable so that the slit will not wear out after the tip is moved in and out many times.  
         [0011]     Other systems, methods, features, and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.  
         [0012]     The present invention disclosed herein provides a retractable writing tool and self-sealing valve that allows for one hand operation, by push button, to retract and protract a tip stored within the valve.  
         [0013]     This design is simple to manufacture and assemble enabling high volume low-cost manufacturing. These are requirements to be a competitive and saleable product in the market. In addition, the design has the enhanced feature and added value, to the end consumer, of being capless, child safe, self-sealing and relatively inexpensive to manufacture, and thus purchase. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The invention can be better understood with reference to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.  
         [0015]      FIG. 1  is a cross-sectional view of a retractable writing tool in the retracted state constructed in accordance with one embodiment of the present invention showing its component parts in operative assembled relationship.  
         [0016]      FIG. 2  is a cross-sectional view of a retractable writing tool in the protracted state constructed in accordance with one embodiment of the present invention showing its component parts in operative assembled relationship.  
         [0017]      FIG. 3  illustrates a writing tool that is disassembled.  
         [0018]      FIG. 4  illustrates a side view of the writing tool in a protracted state.  
         [0019]      FIG. 5  illustrates a side view of the writing tool in a retracted state.  
         [0020]      FIG. 6  is a front perspective view of a valve.  
         [0021]      FIG. 7  is a front perspective view of a valve with a tip extended past the front end and through a slit.  
         [0022]      FIG. 8  is a cross sectional view of a valve.  
         [0023]      FIG. 9  is a perspective view of a valve having a recess around the front end adapted to receive a tension device.  
         [0024]      FIG. 10  is a perspective view of a tension device.  
         [0025]      FIG. 11  is a perspective view of a valve having a planner face and a tension device around the front end.  
         [0026]      FIG. 12  is a cross sectional view of a valve having a convex face.  
         [0027]      FIG. 13  is a cross sectional view of a valve and a slit having lips thicker than the thickness of the rest of the first end.  
         [0028]      FIG. 14  is a cross sectional view of a valve having an array of ribs within and around the first end.  
         [0029]      FIG. 15  is a back perspective view of a valve.  
         [0030]      FIG. 16  is a cross sectional view of the front barrel having tabs.  
         [0031]      FIG. 17  is an enlarged cross-sectional view of a tip and a cartridge in relation to a valve in the retracted position.  
         [0032]      FIG. 18  is an enlarged cross-sectional view of a tip and a cartridge in relation to a valve in the protracted position.  
         [0033]      FIG. 19  illustrates a front view of the opening formed in the elongated portion of  FIG. 20 .  
         [0034]      FIG. 20  illustrates a side view of the cartridge. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]      FIG. 1  illustrates the cross-sectional view of the writing tool  100  in a retracted position. In the retracted position, the tip  101  is within the enclosure  102  with the front end  103  substantially forming a seal, and the back end  104  substantially forming a seal around the second leading section  1702 . The back tip  106  makes contact with the feeder  107  so that the fluid stored in the feeder  107  conveys through the tip  101 . In the retracted position, as the fluid evaporates from the tip  101 , the vapor is substantially sealed within the enclosure  102 .  
         [0036]      FIG. 2  illustrates the cross sectional view of the writing tool  100  in the protracted position. The writing tool  100  includes a gear  200  that works with the plunger  201  and the rear barrel  202  to lock the plunger  201  in the retracted position or the protracted position. To extend the tip  101  outside the opening  203 , the plunger  201  is activated or pushed towards the rear barrel  202 . This causes the cartridge  204 , cartridge plug  205 , feeder  107 , and the tip  101  to move forward towards the opening  203 . As the tip  101  is pushes against the front end  103  of valve  206 , the front end  103  opens to allow the tip  101  to pass through the opening  203  of the front barrel  207 . The compression spring  208  resist against the pushing force until the gear  200  engages and locks in the protracted position. The tip  101  is now ready for the user to apply the fluid to a surface.  
         [0037]      FIG. 3  illustrates the interior components of the writing tool  100 . The writing tool  100  includes a valve  206  adapted to fit within the front barrel  207  adjacent to the opening  203 . The valve  206  has a front end  103  and a back end  104  forming an enclosure  102  within the valve  206 . The enclosure  102  is adapted to receive the tip  101  to substantially seal tip from the outside air and prevent the release of vapor pressure from within the enclosure  102  when the tip  101  is in a retracted position. The tip  101  is coupled to a rod  300  along a longitudinal axis  301 . The tip  101  may be a separate component from the rod  300  or a unitary piece.  
         [0038]     The writing instrument  100  also includes a cartridge  204  adapted to couple to a cartridge plug  205 . The cartridge  204  and cartridge plug  205  are adapted to enclose a feeder  107 . The feeder  107  is adapted to store writing fluid that conveys through the tip  101 . The capillary relationship among the feeder  107  and tip  101  causes the writing fluid to convey from the feeder  107  to the tip  101 . The cartridge  204  has an elongated portion  105  with a first opening  302  adapted to receive the tip  101 . This allows the tip  101  to make contact with the feeder  107  to convey the writing fluid to the tip  101 . The cartridge  204  has a back flange  303  adapted to associate with a compression spring  208 . The elongated portion  105  of the cartridge  204  may be inserted through the compression spring  208  such that the compression spring  208  is positioned between the first opening  302  and the back flange  303 .  
         [0039]      FIG. 4  illustrates a writing tool  100  in a protracted position with a tip  101  extending from the front barrel  207 . The front barrel  207  has an opening  203  to allow the tip  101  to move between a protracted position and a retracted position. The writing tool  100  also has a rear barrel  202  with a rear opening  400  at the back end to allow a plunger  201  to extend between the protracted position and the retracted position. In the protracted position, the plunger  201  is pressed down relative to the rear barrel  202  that causes the tip  101  to extend through the opening  203  and extend from the front barrel  207 .  
         [0040]      FIG. 5  illustrates the writing tool  100  in a retracted position where the tip  101  is inside the front barrel  207 . In the retracted position, the plunger  201  further extends from the rear barrel  202  that causes the tip  101  to retract into the front barrel  207  by moving back into the opening  203 . As such, by activating the plunger  201  between the retracted and protracted positions, the tip  101  is moved correspondingly between the retracted and protracted positions as well.  
         [0041]      FIG. 6  illustrates a perspective view of the valve  206  with the front end  103  and the back end  104 . The front end  103  may have a concaved shape profile with a slit  600  that opens to allow the tip  101  to pass there through. The concave shape profile provides support around the slit  600  to enhance proper closure of the slit  600  when the tip  101  moves back into the valve  206 . The width of the slit  600  may extend from edge to edge of the circumference  601 . In this example, the circumference  601  of the front end  103  may be circular.  
         [0042]      FIG. 7  illustrates a perspective view of the valve  206  with the tip  101  extended past the front end  103  and through the slit  600 . The valve  206  may be made of a material that is durable and flexible so that the slit  600  will not wear out after many cycles of the tip  101  moving in and out of the slit  600 . The material should have low permeability to vapor and air to seal the tip  101 . The type of material used depends on the type of fluid that is used. For water-based fluids with a lower evaporation rate than an alcohol-based writing fluid, silicone may be used to form the valve  206 , but TPE (thermoplastic elastomer), natural rubber, synthetic rubber (e.g. isoprene), and TPV (thermoplastic vulcanizate) material including butyl rubber crossed linked with polypropylene are also preferred. A variety of methods may be used to form the valve  206  such as injection molding, blow molding, extrusion molding, and other methods known to one skilled in the art.  
         [0043]     For alcohol-based fluids with higher evaporation rate, butyl rubber and synthetic rubber (e.g. isoprene), may be compression molded or other methods known to one skilled in the art may be used to form the valve  206 . Alternatively, the valve  206  may be formed from thermoplastic elastomer with thermoplastic rubber that has low permeability to vapor. In addition, the valve  206  may be formed from thermoplastic elastomer and treated with fluorine to further reduce permeation.  
         [0044]      FIG. 8  illustrates a cross sectional view of the valve  206 . Most preferably, the radius of curvature of the front end  103  is between 0 millimeters and 4 millimeters. In addition, a further dimension that is most preferable is the thickness of the concaved shape profile of the front end  103 , may be between about 0.3 millimeters and about 2 millimeters. These dimensions have been found to be very important in providing flexion of the front end  103  and opening and closing of slit  600 . It is preferred that the valve  206  be formed from a single piece of elastomeric material to facilitate easy insertion into the front barrel  207 .  
         [0045]      FIG. 9  illustrates a valve  206  having a recess  900  around the front end  103  adapted to receive a tension device  1000  ( FIG. 10 ). As the tip  101  retracts into the valve  206 , the tension device  1000  applies compression force to the slit  600  to add additional pressure to close the slit  600 . A variety of tension devices may be used around the front end  103 , such as an elastic band and a ring.  FIG. 10  illustrates a tension device  1000  made of metal or plastic to apply compression force to the front end  103 .  
         [0046]     With the tension device  1000 , the front end  103  may have other configurations.  FIG. 11  illustrates the tension device  1000  around the front end  103  having a substantially planner face.  FIG. 12  illustrates the front end  103  having a convex configuration.  
         [0047]      FIG. 13  is a cross sectional view of the valve  206  and the slit  600  having lips  1300  and  1301 . The lips  1300  and  1301  may be thicker at the slit  600  than the thickness of the rest of the front end  103  to allow for greater surface area contact between the lips  1300  and  1301  for better sealing. Other lip configurations may be provided for better seal between the lips  1300  and  1301 .  
         [0048]      FIG. 14  is a cross sectional view of the front end  103  having an array of ribs  1400  around the front end  103  to provide addition support around the slit  600  to close the slit  600 , when the tip  101  moves back into the retracted position. The ribs may also be formed on the interior lips  1300  and  1301  to provide additional support around the slit  600  to close the slit  600 , when the tip  101  moves back into the retracted position. The ribs around the slit  600  may be positioned so that the ribs are off-axis to the longitudinal axis  301  of the slit  600  to provide added support to the closure of the slit  600 .  
         [0049]      FIG. 15  illustrates the back end  104  of the valve  206 . The back end  104  has a hole  1500  adapted to receive the elongated portion  105  with the tip  101  inside. As the tip  101  moves between the retracted and protracted positions, the elongated portion  105  correspondingly moves axially in and out of the hole  1500 . The edges  1501  around the hole  1500  may be beveled to minimize the friction between the back end  104  and the elongated portion  105 . As further illustration in  FIG. 14 , the hole  1500  around the back end  104  may have a concave edge  1402  to minimize the friction with the elongated portion  105 .  
         [0050]      FIG. 16  is a cross sectional view of the front barrel  207  having tabs  1600  and  1601  that are adapted to engage with the cavities  901  and  902  of the valve  206  ( FIG. 9 ). During assembly the valve  206  is inserted into the front barrel  207 , the tabs  1600  and  1601  guide the valve  206  to a predetermined position within the front barrel  207 . This in turn allows the slit  600  to be positioned at a predetermined position as well.  
         [0051]      FIG. 17  illustrates an enlarged cross-sectional view of the tip  101  in relation to the valve  206  in the retracted position. The leading section  1700  of the elongated portion  105  may have three sections, a first leading section  1701 , a second leading section  1702 , and a third leading section  1703 , where the second leading section  1702  is between the first and third leading sections  1701  and  1703 . In the retracted position, the first leading section  1701  is within the enclosure  102 , the second leading section  1702  substantially forms a seal with the back end  104 , and the third leading section  1703  is on the rear side of the back end  104 . The first leading section  1701  tapers downward towards the first opening  302  along the longitudinal axis  301  to make it easier for the first leading section  1701  to pass through the slit  600 . The second leading section  1702  forms a seal with the back end  104  in the retracted position. The circumference around the second leading section  1702  may be about the same or slightly greater than the hole  1500  in the back end  104  to form a seal.  
         [0052]      FIG. 17  illustrates another embodiment of the tip  101  that is adapted to engage within the first opening  302  of cartridge  204 . A variety of different types of tips known to one skilled in the art can be adapted to the first opening  302  of cartridge  204 . In addition, the cartridge  204  may be of a free fluid type adapted to receive a tip embracing a writing ball, similar to a cartridge and tip found in a ballpoint pen.  
         [0053]      FIG. 18  illustrates an enlarged cross-sectional view of the cartridge  204  in relation to the valve  206  in the protracted position. The third leading section  1703  has an array of cavities  1800  that extend back along the elongated portion  105  to minimize the surface area of the third leading section  1703  and collect fluid residue that is built up on the elongated portion  105  as the elongated portion  105  moves into the valve  206  and collects fluid condensation on the inner surfaces of lips  1300  and  1301 . The fluid condensation is forced into the cavities  1800  so that friction caused by fluid build up between the elongated portion  105  and the back end  104  is minimized as the second leading section  1702  moves into the hole  1500  in the back end  104  of valve  206 .  
         [0054]      FIG. 19  illustrates a front view of the first opening  302  formed along the first leading section  1701 . Within the first opening  302  there may be at least one tooth  1900  adapted to engage with the tip  101  to hold the tip  101  in a predetermined position.  FIG. 7  shows an enlarged view of the tip  101 , the tip  101  has an edge  700  with a pitch angle to allow the tip  101  to penetrate through the slit  600  more easily. The tooth  1900  inside the opening  302  may hold the tip  101  so that the edge  700  of the tip  101  may be aligned relative to the slit  600 . With the valve  206  and the edge  700  aligned and held in a predetermined position, the tip  101  may cycle in and out of the slit  600  without damaging the slit  600 .  
         [0055]      FIG. 20  illustrates a side view of the cartridge  204  having at least one flat  2000  adapted to engage within the rear barrel  202 , the rear barrel  202  adapted to receive the flat for guiding the cartridge  204  along an axially direction without rotating. This also ensures that the edge  700  of the tip  101  protracts consistently in relation to the front and rear barrels  207  and  202 . That is, the edge  700  of the tip  101  is substantially prevented from rotating in relation to the front and rear barrels  207  and  202 . In embodiments where the writing tool  100  has a side clip on the rear barrel  202  or an asymmetrically shaped outer configuration, having the tip  101  protracted consistently allows a user to hold the writing tool as intended as well.  
         [0056]     While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of this invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.