Abstract:
A retractable writing device is provided that contains a nib airtight unit with a lid. The nib airtight unit with a lid includes an airtight body, an airtight lid, and/or an elastic loop. The nib airtight unit with a lid is capable of providing effective and durable airtight function for various shapes of nibs.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to a writing device and, more particularly, to a writing device containing volatile writing material.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is known for a pen to adopt a pushing structure that enables the nib of the pen to be retracted. When such a pen is in use, the nib extends outside the shaft of the pen. When not in use, the nib is retracted back into the shaft of the pen. Such a pushing and retractable design enables convenient and portable use of a pen and hence is very popular. However, when the writing material used in a pen, such as a fluorescent pen or marker, is volatile, even a retractable approach does not prevent the writing material from drying. To solve the problem of volatility, an airtight unit can be added to a retractable nib design to ensure that the nib of a volatile pen not only can stretch out and draw back freely, but also is protected against drying when drawn back into the shaft of the pen.  
         [0003]     U.S. Pat. Nos. 6,135,660 and 6,231,257 disclose a pen with an airtight unit for the nib of the pen. The nib airtight unit disclosed in these two patents uses a couple of airtight balls made of elastic and soft materials such as rubber to make up a sealing arrangement to protect the nib of a pen. When not in use, the nib draws back and is isolated in a compartment sealed by both balls. While in use, the nib passes through the two balls. At the same time, the balls change shape and roll until the nib stretches out for writing. Such an airtight unit design has severe shortcomings. For example, the airtight balls can easily become wearied and torn because of the friction that results from pressing and rolling. The airtight balls may thus quickly fail to protect the nib of the pen. In addition, the shape of balls may limit the possible shapes of the nib of a pen.  
         [0004]     Therefore, there exists a need for an airtight unit for a writing device such as a pen that effectively encloses a retracted nib, that is durable, and that is able to accommodate a variety of nib shapes.  
       BRIEF SUMMARY  
       [0005]     Embodiments of the invention address the above-identified needs by providing a retractable writing device that includes a nib airtight unit with a lid. The nib airtight unit is capable of providing effective, stable, and durable protection of various shapes of nibs.  
         [0006]     In one aspect, an airtight retractable writing device includes a shaft, an ink-box in the shaft, a nib connected with the ink-box, and a retractable unit controlling movement of the nib. The writing device further includes a nib airtight unit with a lid for enclosing the nib when the nib is retracted inside the shaft.  
         [0007]     In accordance with another aspect, the nib airtight unit comprises an airtight body and an airtight lid located at the lower part of the airtight body. Each end of the nib airtight unit has a hole that allows the nib or its holding structure to pass through. In one embodiment, when the writing device is in use, the nib passes through the airtight body and pushes open the airtight lid, and becomes exposed outside of the shaft. When the writing device is not in use, the nib is retracted inside the airtight body and the airtight lid closes automatically. The nib airtight unit may further include an elastic structure, such as an elastic loop. One end of the elastic loop ties to the airtight body while the other end of the elastic loop ties to the airtight lid.  
         [0008]     In accordance with yet another aspect, the airtight body comprises an upper body, a lower body, and a circular airtight seal placed between the upper and lower bodies. The airtight seal may be made of soft, elastic materials, and shaped to match with the cross section of the nib or its holding structure. The airtight seal has a hole in the center, whose diameter is smaller than the outer diameter of the nib or its holding structure. The hole allows the nib or its holding structure to pass through by force. Consequently, the airtight seal holds the nib or its holding structure tightly, thus strengthening the airtight effect.  
         [0009]     In accordance with a further aspect, to further strengthen the airtight effect of the lower end of the airtight body, the lower end of the airtight body opposite the lid may include a circular groove, which is embedded with a sealing ring made of soft, elastic materials. The sealing ring may protrude partly over the surface of the lower part of the airtight body. Alternatively, the sealing ring may be attached to the corresponding surface of the airtight lid.  
         [0010]     In summary, embodiments of the invention provide a retractable writing device that contains a nib airtight unit with a lid. The airtight unit and lid provide an effective, stable, and durable structure for protecting various shapes of nibs when the nibs are retracted. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0012]      FIG. 1  is a rear right perspective view of a pushing and retractable fluorescent marker according to one embodiment of the invention, wherein the nib of the marker extends outside the shaft of the marker;  
         [0013]      FIG. 2  is a left side sectional view of the marker illustrated in  FIG. 1 , wherein the nib of the marker is retracted and hidden in the shaft of the marker;  
         [0014]      FIG. 3  is a front right exploded view of the marker illustrated in  FIG. 1 ;  
         [0015]      FIG. 4A  is an upper perspective view of a nib airtight unit suitable for use in the marker illustrated in  FIG. 1 , wherein the lid of the nib airtight unit is closed;  
         [0016]      FIG. 4B  is an upper perspective view of a nib airtight unit suitable for use in the marker illustrated in  FIG. 1 , wherein the lid of the nib airtight unit is pushed open;  
         [0017]      FIG. 5  is a lower perspective and exploded view of the nib airtight unit illustrated in  FIGS. 4A-4B ;  
         [0018]      FIG. 6  is a perspective view of the lower shaft of the marker illustrated in  FIG. 1 ; and  
         [0019]      FIG. 7  is an exploded perspective view of the ink-box and retractable unit for the marker illustrated in  FIG. 3 . 
     
    
     DETAILED DESCRIPTION  
       [0020]     The following description provides an overview and detailed description of one example of an airtight retractable writing device constructed in accordance with the present invention. Further provided is an applied example for operating such a writing device. While illustrative examples are described herein and parts for assembling embodiments of the invention are shown, these specific examples and parts are not intended to be exhaustive or to limit the invention to the precise forms disclosed. For example, the preferred embodiment described in detail below illustrates a fluorescent marker. However, the invention is applicable to any retractable writing device, especially when the writing material in the writing device is volatile. Moreover, the particular number, shape, and size of parts described herein are not limiting to the invention, as parts may be combined or divided out in manufacturing (thus reducing or increasing the number of parts). The shape or size of parts may also be modified or parts may be eliminated or added without departing from the scope of the invention as defined by the claims. Such alternative designs can be assembled and achieve the benefits and advantages of the present invention.  
         [0000]     Structure and Assembly of an Embodiment  
         [0021]      FIGS. 1-7  illustrate a structure and assembly of one exemplary embodiment of an airtight pushing and retractable fluorescent marker (hereinafter “marker”) constructed in accordance with the present invention. As shown in  FIGS. 1-3 , this embodiment of the marker comprises a shaft  1 , an ink-box  2 , a nib  3 , a retractable unit  4 , and a nib airtight unit  5 . The discussion below describes in detail an exemplary embodiment for each of these components of the marker.  
         [0022]     As shown in  FIG. 3 , the shaft  1  comprises an upper shaft  1 A and a lower shaft  1 B. The lower end of the upper shaft  1 A contains a thin interface  1 A 1  and a couple of symmetric holes  1 A 2 . Correspondingly, the upper end of the lower shaft  1 B contains a thin interface  1 B 1  and a couple of symmetric flanges  1 B 2 . As shown in  FIG. 6 , this exemplary embodiment includes straight grooves  1 B 4  on the inner wall of the lower shaft  1 B. The grooves  1 B 4  are configured to receive flanges  5 A 4  ( FIG. 4A ) as will be discussed later herein. The interface  1 B 1  of the lower shaft  1 B is inserted into the interface  1 A 1  of the upper shaft  1 A. The symmetric flanges  1 B 2  are embedded in the symmetric holes  1 A 2 . In such a way, the upper shaft  1 A and the lower shaft  1 B are joined together.  
         [0023]     As shown in  FIGS. 2, 3 , and  7 , the ink-box  2  comprises a packed wick  2 A, an inner shaft  2 B, and a middle shaft  2 C. The packed wick  2 A is inserted inside the inner shaft  2 B, which is fixed together with the middle shaft  2 C. The upper section  3 A of the nib  3  is inserted tightly into the lower end of the middle shaft  2 C and connected to the packed wick  2 A. The lower end of the middle shaft  2 C includes a nib clip.  
         [0024]     As shown in  FIG. 3 , the retractable unit  4  comprises a push-button  4 A, a roller  4 B, a return spring  4 C, and a straight flange (not shown) inside the shaft. The straight flange refers to the characteristic of a long straight groove (not shown in the drawings). The return spring  4 C is slipped over the middle shaft  2 C. Because pushing structures suitable for controlling the retractable unit  4  are well known in the industry, further details herein are not necessary to implement the pushing structure.  
         [0025]     As shown in  FIGS. 3-5 , the nib airtight unit  5  comprises an airtight body  5 A, an airtight lid  5 B, and an elastic loop  5 C, which can be a rubber band or spring, for example. In an exemplary embodiment of the invention, the airtight body  5 A includes an upper body  5 A 1 , a lower body  5 A 2 , and an airtight seal  5 A 3 . The lower body  5 A 2  is tightly fitted to the upper body  5 A 1 . The airtight lid  5 B and the lower body  5 A 2  may be constructed as one unit, which may be cast with a flexible organic plastic. The airtight lid  5 B and the lower body  5 A 2  connect at a uniting section  5 B  1 .  
         [0026]     The airtight seal  5 A 3  is pressed between the lower body  5 A 2  and the upper body  5 A 1 . The center of the airtight seal  5 A 3  has a hole, whose diameter preferably is less than that of the upper section  3 A of the nib  3 . Made of elastic or soft materials, the airtight seal  5 A 3  not only allows the upper section  3 A of the nib  3  to be inserted there through and to move up and down, but also continuously seals against the upper section  3 A of the nib  3 .  
         [0027]     As shown in  FIGS. 4A and 4B , to ensure the airtight function of the lid  5 B, the airtight unit  5  may further include an elastic loop  5 C. The elastic loop  5 C may be made of organic material with high elasticity or may be a metallic or plastic spring. The airtight lid  5 B may include lower agraffes  5 B 2 , which are used to secure one end of the elastic loop  5 C. The other end of the elastic loop  5 C may be secured to an upper agraffe  5 A 5  on the upper body  5 A 1 . When the nib  3  is retracted within the airtight unit  5 , the elastic loop  5 C forces the lid  5 B to shut against the lower body  5 A 2 , as shown in  FIG. 4A . When the nib  3  is extended outward from the airtight unit, the nib  3  forces the lid  5 B to go open, for example as shown in  FIG. 4B .  
         [0028]     Optionally, to further enhance the airtight function of the lid  5 B, a sealing ring  5 A 7  made of soft materials may be provided. The sealing ring  5 A 7  may be secured to the surface of the lower part of the lower body  5 A 2  or the corresponding surface of the airtight lid  5 B. As shown in  FIG. 5 , the lower part of the lower body  5 A 2  includes a circular groove  5 A 6  into which the sealing ring  5 A 7  may be tightly fitted. As shown in  FIG. 3 , the sealing ring  5 A 7  protrudes partly over the surface of the lower part of the airtight body  5 A. In addition, as shown in  FIG. 2 , the surface of the lower part of the airtight body that is opposite the airtight lid may be configured at an incline relative to a longitudinal axis that extends through the airtight body.  
         [0029]     As shown in  FIGS. 4A and 4B  and in  FIG. 6 , the upper body  5 A 1  of the airtight body  5 A includes flanges  5 A 4 , which fit to the straight grooves  1 B 4  on the inner wall of the lower shaft  1 B. The flanges  5 A 4  and the straight grooves  1 B 4  thus secure the nib airtight unit  5  within the lower shaft  1 B.  
         [0000]     Operation of the Disclosed Embodiment  
         [0030]     Once the marker is assembled, for example, according to the embodiment described above, the nib  3  of the marker can extend or retract upon the pushing of the push-button  4 A. When the marker is not in use, as shown in  FIG. 2 , the push-button  4 A returns to the top of the marker by the force of the return spring  4 C. The nib  3  retracts inside the airtight body  5 A while the airtight lid  5 B is closed against the airtight unit  5  by the force of the elastic loop  5 C. When the marker is to be used, as shown in  FIG. 1 , the push-button  4 A is pushed down, which compresses the return spring  4 C. In turn, the nib  3  moves down the shaft  1  along with the ink-box  2  and the middle shaft  2 C until the nib  3  extends outside the lower shaft  1 B and is ready for writing. The downward movement of the nib  3  forces the lid  5 B to open and allow the nib  3  to extend outside the shaft  1 . When the push-button  4 A is pushed again, the nib returns to the retracted state shown in  FIG. 2 . When the nib is retracted, the elastic loop  5 C pulls the lid  5 B shut, thus returning the unit  5  to an airtight state.  
         [0031]     In exemplary embodiments of the invention, if the packed wick  2 A of the ink-box  2  is saturated with florescent ink, the marker may be considered a pushing and retractable fluorescent pen. If the packed wick  2 A is saturated with marker ink, the marker may be considered a pushing and retractable marker.  
         [0032]     While an exemplary embodiment of the marker has been illustrated and described above, along with alternative embodiments and an exemplary implementation of the marker, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention. The scope of the invention should be determined from the following claims and equivalents thereto.