Patent Publication Number: US-7707734-B2

Title: Hands free chalk line snapper

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority of U.S. Provisional Patent Application Ser. No. 60/962,389, filed Jul. 27, 2007 under 35 U.S.C. §119(e). 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a hands free device for marking a chalk line for use in construction, home improvement and the like. 
     Conventional chalk line marking devices employ a chalk line that is wound up around a spool within a case or dispenser. During use, the chalk line is extended and held taut near the workpiece surface to be marked. Typically, this requires two workers—one to hold the end of the chalk line and one to hold the dispenser. The chalk line is then grasped and released by one of the workers so that it snaps back toward the surface, thereby depositing a chalk line on the workpiece surface. Or, one worker may devise a way to secure one end of the line using a weight or the like. In any event, the procedure is inconvenient. A handle is attached to the dispenser to allow the line to be wound back into the case after use. 
     U.S. Pat. No. 6,944,962 discloses a chalk line marking device with an internal trigger mechanism for snapping a chalk line in combination with a chalk line positioning element. This marking device is quite complicated and costly in comparison to the within invention. Further, the &#39;962 patent device does not snap the chalk line at a position remote from the device, nor does it disclose a plunger mechanism or cone-shaped housing as in the within invention. 
     SUMMARY OF THE INVENTION 
     A principle object of the present invention is to provide a chalk line that is “hands free.” That is, a chalk line that can be operated and “snapped” by a single user, without requiring the assistance of a second worker. More particularly, it is a principle object of this invention to provide a chalk line that can be snapped by only one hand of the single user while the user&#39;s other hand is holding the chalk line in an extended position. 
     It is a further object of this invention to provide a chalk line dispensing device that includes a mechanism for lifting the chalk line away from the surface of the workpiece and then suddenly returning the chalk line to the surface, thus snapping the chalk line. The mechanism can be operated by one hand of the user, typically employing the user&#39;s thumb. 
     A chalk line marking device according to embodiments of this invention allows the user to easily mark a line in a desired location on a wall, floor or other surface without the need for another person. The invention provides a spring-loaded mechanism for snapping a linear chalk line against a surface to be marked, using only the hand holding the chalk line dispenser. The device is particularly useful for amateur and professional carpenters, kitchen cabinet installers, tile setters and so forth. 
     The chalk line marking device comprises a chalk line housing for storing, dispensing and retracting the chalk line around a spool or similar mechanism within the device. The housing is held in one hand of the user while the end of the chalk line is withdrawn by the other hand. The housing also has a handle, attached internally to the axis of the spool, which is used to re-wind or retract the chalk line into the dispenser after use. In the preferred embodiments, the marking device also includes a spring loaded mechanism connected to a gripper which can be actuated by the user. The gripper extends from the marking device and operates to lift the chalk line upward from the work surface at a position remote from the device. When the gripper is released, the spring causes the gripper to forcefully return to its original position, thereby snapping the chalk line and leaving a linear chalk mark on the workpiece surface. The gripper may comprise a handle for actuation by the user&#39;s thumb of the hand holding the housing, while the user&#39;s other hand holds the withdrawn end of the chalk line. 
     In a preferred embodiment, the chalk line marking device includes a spring loaded mechanism consisting of a coil spring affixed to the outer surface of the housing, located on the lower portion of the housing near an opening from where the chalk line is withdrawn. The coil spring could be permanently attached to the housing, or it could be removable. A gripper is connected at the lower end of the coil spring, at a point from which it pivots, and extends along the chalk line to a position remote from the housing. The end of the gripper comprises a hook which is placed under the chalk line. A handle may extend upward from the gripper at some point along its length, for access by the user&#39;s thumb to actuate the snap lever. By exerting lateral pressure on the handle, the user causes the gripper to pivot at its pivot point and therefore raise the chalk line, passing over the hook, from the surface of the workpiece remote from the housing. When the chalk line is raised to a sufficient degree, the handle is released and the spring causes the gripper and the hook to return forcefully to the workpiece surface, “snapping” the chalk line. In this embodiment, use of the device with one hand is facilitated. 
     In one embodiment of the chalk line marking device, the gripper is foldably attached to the housing without having a coil spring. When unfolded, the gripper extends away from the housing and has a hook for sliding under the chalk line, when the chalk line is extended. When stretched taut, the chalk line provides downward pressure on the hook and the gripper. Thus, when the gripper is raised from the workpiece surface by the user&#39;s thumb, tension in the chalk line causes the gripper to return suddenly to the workpiece surface when the gripper is released. 
     In another embodiment of the chalk line marking device, the gripper is located vertically and entirely within the dispenser. The lower end of the gripper comprises an eye through which the chalk line passes. The upper end of the gripper lever is configured to rest upon the upper surface of a ratchet or rotatable snap gear. When the snap gear rotates in a “tension cycle,” it exerts upward pressure on the gripper, creating upward movement and creating tension on the internal spring. The upward movement raises the gripper and the chalk line from the workpiece surface. Continuing to rotate, the snap gear enters a “release cycle” wherein the gripper is suddenly propelled downward by force of the coil spring to the surface of the workpiece, snapping the chalk line. The snap gear can be actuated by a thumb button or small electric motor. 
     In a further embodiment of the chalk line marking device, the housing is cone-shaped and has an opening at the bottom and on the side of the cone through which the chalk line passes when extended. The opening on the side is a vertical slot which allows the chalk line to raise from the surface of the workpiece when it is lifted by an internal gripper. The housing also comprises a plunger that is actuated by downward pressure from the user&#39;s palm. When pressure is applied, the upper portion of the housing moves downward toward the cone-shaped portion of the housing, which actuates the internal gripper. The gripper is comprised of a collar and a sleeve, which is spring loaded, and which has a central channel for the chalk line. As the plunger moves downward, the collar and sleeve move upward by actuation of gears at the side. When the collar and sleeve reach a pre-determined height, the collar and sleeve holding the chalk line are suddenly released, snapping the chalk line to the surface of the workpiece. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description of embodiments of the invention taken in connection with the accompanying drawings. 
         FIG. 1  is a perspective view of the chalk line marking device which includes an external coil spring-loaded gripper in accordance with an embodiment of the invention. 
         FIG. 2  is a side view of the embodiment of  FIG. 1 . 
         FIG. 3  illustrates a worker actuating the gripper of the embodiment of  FIG. 1 . 
         FIG. 4   a  is a front view of an embodiment of the invention having a foldable gripper. 
         FIG. 4   b  is a side view of the embodiment of  FIG. 4   a  having the gripper folded against the housing. 
         FIG. 4   c  is a perspective view of the embodiment of  FIG. 4   a  illustrating the gripper positions. 
         FIG. 5   a  is a view of a ratchet or snap gear of an embodiment of the invention during the tension cycle. 
         FIG. 5   b  is a further view the embodiment of  FIG. 5   a  during the release cycle. 
         FIG. 5   c  is a further view the embodiment of  FIG. 5   a  showing a method for actuating the snap gear. 
         FIG. 6   a  is a cross-sectional view of an embodiment of the invention having an internal gripper comprised of a sleeve and collar. 
         FIG. 6   b  is a close-up view of the embodiment of  FIG. 6   a.    
         FIG. 6   c  is an external close-up view of the embodiment of  FIG. 6   a.    
         FIG. 6   d  is a perspective view of the tip of the chalk line snapping device of  FIG. 6   a.    
         FIG. 6   e  are two plan views of the collar employed in the embodiment of  FIG. 6   a , showing rotation of a sleeve within a collar. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The preferred embodiments of the present invention will now be described with reference to  FIGS. 1-6  of the drawings. Identical elements in the various figures are designated with the same reference numerals. 
       FIGS. 1-3  illustrate a first preferred embodiment of the hands free chalk line snapper according to the present invention, generally designated by the reference number  10 . The chalk line snapping device comprises a housing  12  for dispensing, storing and retracting the chalk line  14 , which is wrapped around a spool  16  or similar mechanism contained within housing  12 . The housing  12  is held in one hand of the user (see  FIG. 3 ) while the end of the chalk line is withdrawn by the other hand. The device also has a handle  18  attached internally to the axis of the spool, which is used to re-wind or retract the chalk line  14  into the housing  12 . 
     The chalk line snapping device of this embodiment also includes a coil spring  20  connected to a gripper  22 , which extends from the coil spring  20  and operates to lift the chalk line  14  upward from the workpiece surface  24 . The coil spring could be permanently attached to the housing  12 , or it could be removable. Gripper  22  is connected at the lower end of the coil spring  20 , at a point from which it pivots  26 , and extends along the chalk line  14 . The end of the gripper  22  comprises a hook  28  which is placed under the chalk line  14 . Gripper  22  also comprises a thumb handle  30  extending vertically from the gripper  22  at a point along its length. The user actuates the gripper  22  by exerting upward pressure with the user&#39;s thumb on the thumb handle  30 . This causes the gripper  22  to pivot at its pivot point  26  from a resting position  32  on the workpiece surface  24 , and therefore raise the chalk line  14 , passing over the hook  28 , to a raised position (see  22 ) from the workpiece surface  24 . When the chalk line  14  is raised to a sufficient degree, the user releases the thumb handle  30  and the coil spring  20  causes the gripper  22  and the hook  28  to return forcefully to the workpiece surface  24 , “snapping” the chalk line  14  and leaving a linear chalk mark on the workpiece surface  24 . 
       FIGS. 4   a - 4   c  illustrate a second preferred embodiment of the present invention. In this embodiment of the chalk line snapping device  10 , the gripper  34  is externally attached to the housing  12  at a pivot point  36 , at a lower portion of the housing  12 . The attachment of the gripper  34  at the pivot point  36  allows the gripper  34  to be folded against the housing  12 , where it can be stored  31  and held in place by means of a snap fitting  35  on the side of the housing  12 , when the gripper is not in actual use. The configuration of the gripper  34  is such that its shape conforms to the outside shape of the housing. One end  38  of the gripper  34  is configured to attach to the housing  12  at the pivot point  36 , while the opposite end of the gripper  34  comprises a hook  39  over which the chalk line  14  passes when the gripper  34  is unfolded in an extended position  37 . See  FIGS. 4   a  &amp;  4   c . The gripper  34  further comprises a thumb lever  40  located at approximately the center of the length of the gripper  34 . As shown, thumb lever  40  can be simply an angle bend in the gripper  34 , or could be any other type of tab, extension or lever that could be configured to be engaged by the user&#39;s thumb when the gripper is in the unfolded position  37 . As seen in  FIG. 4   c , when the gripper  34  is in the unfolded position  37 , the chalk line  14  passes over the hook  39  when the chalk line  14  is extended along the workpiece surface. When the chalk line  14  is held taut, tension is provided on the gripper  34 , much like the tension a spring would provide in another embodiment. In operation, the user applies upward pressure at the thumb lever  40 , causing the chalk line  14  to be raised from the workpiece surface at position of the hook  39 , remote from the housing  12 . When the user releases the thumb lever  40 , the tension from the chalk line  14  on the hook  39  causes the gripper  34  to return forcefully to the workpiece surface  24  ( FIG. 4   c ), “snapping” the chalk line  14 . 
       FIG. 4   c  illustrates the deployment of the gripper  34  of this embodiment, from a folded or stored position  31  to an extended or unfolded position  37 . In so deploying, the gripper  34  rotates at the pivot point  36  as indicated by arc  41 . 
       FIGS. 5   a - 5   c  illustrate another embodiment of the chalk line snapping device where the snapping mechanism is contained within the housing. The gripper  42  is located vertically within the housing  12  ( FIG. 5   c ). The lower end of the gripper  42  comprises an eye  44  through which the chalk line  14  passes. The upper end  46  of the gripper  42  is configured to rest upon the upper surface of a rotatable ratchet gear  48 . When the ratchet gear  48  rotates during a “tension cycle” ( FIG. 5   a ), diagonally inclined teeth  50  exert upward pressure on the gripper  42 , creating upward movement and creating tension on the internal coil spring  52 . The upward movement raises the chalk line  14  from the workpiece surface. Continuing to rotate, when the ratchet gear  48  enters a “release cycle” ( FIG. 5   b ), i.e., when the upper end of the gripper  42  reaches the upper edge of teeth  50 , the gripper  42  is suddenly propelled downward by force of the coil spring  52 , to the surface of the workpiece, snapping the chalk line  14 . The ratchet gear  46  can be actuated by a thumb button  54  located on the side of the housing  12 , or by a small D.C. electric motor  56 . The electric motor  56  would have a drive gear  58  for engagement with corresponding gear teeth  60  on the ratchet gear  48 . 
       FIGS. 6   a - 6   e  illustrate another preferred embodiment of the chalk line snapping device where the internal snapping mechanism is actuated by downward pressure  62  on the top of the housing  12 . In this embodiment, the housing  12  is comprised of an upper plunger portion  74  that is slidably connected to a lower, cone-shaped portion  76 . Lower portion  76  has a vertical slot  78  which allows for egress of the chalk line when it is lifted from the workpiece surface by the gripper  64 . The plunger portion  74  is configured to move with respect to the lower portion  76  when downward pressure is applied, thus activating the gripper  64  as further explained herein below. Lower portion  76  also has an opening  80  at the bottom of the cone for exiting the chalk line. 
     Gripper  64  is comprised of a hollow sleeve  66 , through which the chalk line (not shown) passes, and having a collar  68  around the sleeve  66 . The sleeve  66  is rotatable within collar  68 , and also comprises a spring  79  for providing downward pressure on the sleeve  66 . The sleeve  66  also comprises an upper cylinder  72  configured to cause sleeve  66  to rotate when it is raised. The serrated gears on the cylinder  72  contact a fixed object (not shown) rotating the sleeve  66  causing nipples  67  to slide off the shoulder formed by the top of collar  68  into slide grooves  69  in collar  68  as shown in  FIG. 6   e . Collar  68  also has teeth  70  vertically arranged on both sides for interconnection with fixed gears  81 . Plunger  74  further comprises internal levers  82  also having teeth  84  for interconnection with the teeth on the fixed gears  81 . 
     In order to crease a chalk mark on the workpiece surface using this embodiment, the device is vertically placed on the workpiece surface with the lower cone-shaped portion  76  being in contact with the surface. The chalk line is drawn outward from the housing  12  by one hand of the user, passing through opening  80  and vertical slot  78  in the cone-shaped lower portion  76  of the housing, and held taught. The user then applies downward pressure on plunger  74  with the other hand, causing it to slide downward with respect to the lower cone-shaped portion  76 , which remains stationary. The downward motion of plunger  74  causes the internal levers  82  to also move downward, causing the fixed gears  81  to rotate against the teeth  70  of the gripper collar  68 . The rotation of the fixed gears  81  raises the gripper  64  and the chalk line from the workpiece surface, the chalk line extending through the vertical slot  78 . Spring  79  provides downward tension against the gripper  64  as it is being raised. As sleeve  66  is forced upward, it reaches a point of disengagement with the collar  68 . The sleeve  66  then rotates out of a locked position in the collar  68  into slide grooves of collar  68 , where the spring  79  then suddenly returns the gripper  64  to the workpiece surface, thus snapping the chalk line. This embodiment operates in a similar manner as a ballpoint pen up/down mechanism. 
     While the invention has been described and illustrated in connection with the preferred embodiments, many variations and modifications as will be evident to those of skilled in this art may be made without departing from the spirit and scope of the invention, and the invention is thus not limited to the precise details of methodology or construction set forth above as such variations and modifications are intended to be included within the scope of the invention.