Abstract:
A chalk box for producing a chalk line without leakage of chalk dust from within. The chalk box has a chalk-filled chamber that houses a spool and a flexible chalk line. The chalk line extends outwardly around a guidepost and through a fibrous tube. The fibrous tube snugly hugs the flexible line, preventing chalk dust from leaking through the tube. The chalk dust impregnating the flexible line provides lubrication for its passage through the fibrous tube. The present invention also includes a built-in pencil sharpener isolated from the chalk dust, for the convenience of the user.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to the field of measurement tools, and more specifically to a device for producing a chalk line on a rough surface, such as at a construction site. The chalk box contains a loose chalk dust and a retractable line capable of being extended while chalked and marking a chalk line when snapped. 
     BACKGROUND OF THE INVENTION 
     Chalk boxes are well known in the construction field and have long been used to mark construction lines. The chalk preferred for use as the marking medium is brightly colored and indelible, leaving a readily visible and enduring chalk line not easily obscured by the heavy foot traffic inherent at a construction site. One persisting problem with known chalk boxes is their tendency to leak chalk dust, both when the line is extended during use and also during carrying between uses. Chalk dust leakage is a problem for several reasons. One such reason is that indelible chalk dust produces a brightly colored stain that is difficult to remove from clothing and/or other surfaces that are not desired to be marked. Finely powdered chalk dust tends to have almost-liquid flow characteristics, and thus even if the chalk box is carried in a pocket, the leaked chalk dust does not long remain confined. Further, as construction technology progresses, increasingly complex and delicate electronic tools, equipment, and measurement devices are becoming commonplace at the work site. These tools, such as computers, laser measurement devices, ultrasonic probes, and the like are all susceptible to damage from dust contamination. While care is taken to protect them from airborne dust intrusion, accidental direct introduction of chalk dust from the clothing or hands of an operator could cause expensive and time-consuming equipment damage. Moreover, leaked chalk dust staining the work site can obscure or confuse the intentionally laid chalk lines, again resulting in the need for repeated measurements and other costly delays, decreasing productivity at the work site. Finally, chalk dust leakage necessitates more frequent replacement of the chalk dust in the chalk box, again decreasing efficiency and productivity. 
     Typically, the worker using the chalk box also makes other measurement markings at the construction site. Some of these markings involve using regular or colored pencils. When these pencils become dull, the worker typically uses a knife or utility blade to crudely sharpen them, a process that is inefficient and wasteful in that useful pencil is typically shaved off along with the wood. Since workers must carry their equipment with them, most find it inconvenient to carry a small, loose pencil sharpener when they already have a knife. Providing a pencil sharpener that does not add to the number of tools the worker must carry would therefore increase efficiency and enhance productivity. 
     At the work site, productivity is one of the keys to remaining competitive and making a profit. Tools that decrease work site delays and increase efficiency and productivity therefore help to increase profit. Therefore, a need arises for a chalk box that minimizes chalk dust leakage. There is a further need for providing a pencil sharpener that does not further encumber the worker. The present invention satisfies these needs. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a chalk box for producing a chalk line that decreases the amount of chalk dust leakage common to known chalk boxes. In one embodiment, a narrow exit tube is formed through which the chalk line exits the chalk box. The tube is surrounded by a fibrous material and is formed just wide enough for the line to pass through. The passage of the line through the tube is facilitated by the lubrication effect of the chalk powder impregnating the line. A built-in pencil sharpener is also provided for the convenience of the user. 
     One object of the present invention is to provide an improved chalk box. Related objects and advantages of the present invention will be apparent from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top exploded partial perspective view of the interior of the preferred embodiment of the present invention. 
     FIG. 2 is bottom exploded partial perspective view of the embodiment of FIG. 1, showing the empty gear chamber within the housing. 
     FIG. 3 a  is another bottom partial perspective view of FIG. 2, showing the gears in the gear chamber. 
     FIG. 3 b  is yet another bottom partial perspective view of FIG. 2, showing the spool connected to the enclosed gear chamber. 
     FIG. 4 a  is a top perspective view of the embodiment of FIG.  1 . 
     FIG. 4 b  is a bottom perspective view of the embodiment of FIG.  1 . 
     FIG. 4 c  is a top plan view of the embodiment of FIG.  1 . 
     FIG. 4 d  is a side elevational view of the embodiment of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. FIGS. 1-4 illustrate one preferred embodiment of the present invention, a chalk box  10 , having a housing  12  having an anterior end  13  and an anterior portion  14  and a posterior end  15  and a posterior portion  16 . The anterior portion  14  further includes an anterior aperture  18  formed therein, and the posterior portion  16  includes a posterior aperture  19  formed therein. The housing  12  may be characterized in greater detail as defining a gear chamber  20 , a chalk chamber  22 , an anterior chamber  24 , and a posterior chamber  26 . 
     The gear chamber  20  houses a winding gear  30  and a spool-engaging gear  32 . Winding gear  30  is fixedly mounted on winding shaft  34 . Winding shaft  34  is rotationally mounted in gear chamber  20  and extends through the housing  12  to connect to winder  36 . Winder  36  is preferably pivotally connected to winding shaft  34 , such that winder  36  may be pivoted to lie flush with housing  12  when not in use and be pivoted upwardly from housing  12  for easy gripping when in use. The gear chamber  20  further includes an interior cover portion  29  adapted to isolate the gears  30 ,  32  from the remainder of the interior of the chalk box  10 , so as to prevent chalk dust from contaminating and damaging the gears  30 ,  32 . 
     Spool engaging gear  32  is fixedly mounted on spool shaft  38 . Spool shaft  38  is rotationally mounted in chalk chamber  22  with a gear-engaging portion  40  extending into gear chamber  20 . Spool  42  is positioned in chalk chamber  22  and is fixedly coupled to spool shaft  38 . Spool  42  further includes a top disc  43  and a bottom disc  44  fixedly mounted to spool shaft  38  and spaced apart. 
     Chalk chamber  22  is adapted to contain a quantity of chalk dust. Gear chamber  20  is adapted to isolate gears  30 ,  32  from the chalk dust in chalk chamber  22 . Anterior chamber  24  is in communication with chalk chamber  22  through a throat  45  defined by their junction, allowing the passage of chalk dust back and forth between the chambers  22 ,  24 . Preferentially, anterior chamber  24  also contains a guide post  46  positioned near the throat  45 , although the guidepost  46  could be positioned in the chalk chamber  22 . Posterior chamber  26  is adapted to contain a pencil sharpener  48  in isolation from any chalk dust in chalk chamber  22 . Anterior chamber  24  is also adapted to contain a plurality of baffles  52  formed therein between the guidepost  46  and the anterior aperture  18 . The baffles  52  are substantially collinear with the guidepost  46  and the anterior aperture  18  and are provided to support a line guide tube  54 . Guide tube  54  is positioned such that it extends substantially collinearly with aperture  18  and guidepost  46 . It is preferred that fibrous wadding or packing  56  at least partially fill around baffles  52 , supporting tube  54  and providing an additional dust seal. 
     A flexible line  60  is windingly coupled to spool  42  between top and bottom discs  43 ,  44  such that rotation of spool  42  winds flexible line  48  therearound. Flexible line  60  extends through chalk chamber  22 , through throat  45 , around guidepost  46  and through tube  54  to pass through anterior aperture  18 . Flexible line  60  is adapted to easily pick up and deposit chalk dust. Tube  54  and the fibrous packing  56  are adapted to remove excess chalk dust from flexible line  60  as it passes therethrough, substantially preventing loose chalk dust from exiting tube  54  and allowing only that chalk dust adhering to flexible line  60  to pass through the tube  54 . Preferably, tube  54  is sized to snugly hug flexible line  60  as it passes therethrough. The loose, excess chalk dust removed from flexible line  60  as it enters the tube  54  is returned to the chalk chamber  22 , while the quasi-interference fit of flexible line  60  in tube  54  further discourages chalk dust leakage from chalk box  10 . 
     Winding gear  30  is meshingly engaged with spool engaging gear  32 , such that rotation of winding gear  30  actuates rotation of spool-engaging gear  32 . Likewise, rotation of spool-engaging gear  32  causes rotation of the fixedly connected spool shaft  38  and spool  42 . Rotation of spool  42  causes flexible line  60  to wind around the spool  42 , thereby retracting flexible line  60  into chalk chamber  22 . Spool shaft  38  is adapted to freely rotate, such that a worker may easily extend flexible line  60  from housing  12  by holding chalk box  10  steady and pulling on flexible line  60 . Preferably, the gear ratio (the ratio of the number of teeth of one gear to the number of teeth of another gear) of the winding gear  30  to the spool-engaging gear  32  is substantially large. More preferably, the gear ratio of the winding gear  30  to the spool-engaging gear  32  is at least about 4:1. 
     Chalk chamber  22  also features a port  70  formed thereinto, through which chalk chamber  22  may be filled with and/or emptied of chalk dust. Flexible or rigid seal  72  may be employed to plug port  70 . Preferably, seal  72  is a sliding door, although seal may be of any convenient type for preventing undesired communication of chalk dust from chalk box  10 . 
     Posterior chamber  26  includes a pencil sharpener  48  mounted therein. Pencil sharpener  48  is adapted to be accessed by pencils through posterior aperture or orifice  19 . Posterior aperture  19  is operationally aligned with pencil sharpener  48 . Posterior aperture  19  is preferably partially plugged with cross-slotted flexible plug  76 , which is adapted to allow the passage of a pencil therethrough while at least partially blocking the inadvertent passage of foreign objects thereinto and/or pencil shavings therefrom. Posterior chamber  26  further includes a cleanout port  80  through which accumulated pencil and/or wood shavings may be emptied. Cleanout port  80  is plugged by flexible plug  82 , adapted to snugly fit therein. 
     Preferably, chalk box  10  is constructed from an inexpensive, lightweight structural material such as plastic (preferred), aluminum, or wood, although any convenient material may be chosen. Further, the flexible plugs are preferably formed from rubber or flexible plastic, although any convenient flexible or pliable material may be selected. Still further, the gears are preferably formed from plastic, although any convenient structural material may be chosen. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.