Patent Document

BACKGROUND 
     The present invention relates to a hand held weed trimmer and, more particularly, to a weed trimmer having an accuracy shield affixed thereto that protects and stabilizes the rotating line. 
     In general, weed trimmers or weed wackers are quite common and they normally comprise a motor located at either the proximal end or the distal end of an elongated shaft and a rotating spindle at the distal end, with the rotational movement of the motor being transmitted to the spindle. There is also normally an intermediate handle along the elongated shaft to provide stability and to facilitate the handling of the weed trimmer by the user. 
     A plastic line extends radially outwardly from the rotating spindle such that the line spins rapidly along with the rotating spindle to cut the vegetation such as weeds or grass, that come in contact with the line. There is also a conventional line extending system that allows the line to be played out incrementally by hitting the bottom of the rotating spindle on the ground (bump) which then releases the line to extend further outwardly from the spindle. The actual outward movement of the plastic line is accomplished by centrifugal force created in the line by the rotating spindle and the line plays out by that force and the outer end is cut to a predetermined length by a line cutter that is provided on the housing to cut the line to a specific length. 
     One of the difficulties with current weed trimmers is in the control of the device, even with the elongated handle and the intermediate handle and the location of the end of the line is somewhat uncertain and not stable, particularly when using the weed trimmer as an edger to neaten the edge of a lawn. In edging, the line spins in a generally vertical plane and the depth and uniformity of the cut edge is difficult to maintain over the length, for example, of a driveway. 
     Another difficulty with the present weed trimmers is with the line extending system that plays out the line when the line is released, that is, it is played out by centrifugal force however, if the line is inadvertent cut too short by encountering some obstacle, the line may not be sufficiently long to create the needed centrifugal force to cause the line to play out from the rotating spindle, such that the line must be manually pulled out, thereby negating the usefulness and convenience of the automatic line extending system. 
     As a further difficulty, the present lawn trimmers, when used as an edger by turning the trimmer to an orientation where the plane of the rotating line is about vertical, the user has little stability at the distal end and therefore the trimming is not consistent and neat. Instead, the distal end wavers as the person walks and the trimmed edge lacks the appearance of a straight, neat line formed in the edge of the grass. 
     It would therefore be advantageous to have a weed trimmer that had better control of the length of the line to avoid it being cut or broken off too short as well as additional control of the end of the line to better cut the weeds or grass in a uniform manner, whether during the process of normal grass trimming or edging. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention overcomes the aforesaid difficulties by providing a weed trimmer that is adapted to cut vegetation and includes an elongated support with a proximal end that can be held by a user and a distal end having a housing within which is a rotating spindle having a flexible line extending radially therefrom. The rotation of the spindle and line is provided by a motor that can be electric or internal combustion and may be physically located at the proximal end or the distal end of the weed trimmer. 
     There is an accuracy shield that is provided and which is generally planar, having a thickness of about 0.25 inches and which is affixed at a location between the rotating line and the housing. The accuracy shield may be constructed of a plastic material and is affixed to the housing oriented in a plane that is generally parallel to the plane of rotation of the rotating line. 
     With the accuracy shield, the rotation of the line is stabilized and the line is prevented from being inadvertently cut too short such that there is insufficient centrifugal force generated to allow the line to play out when released by hitting the bottom of the spindle. 
     The presence of the accuracy shield is also advantageous to act as a guide when using the weed trimmer as an edger where the weed trimmer is oriented such that the line rotates in a generally vertical plane. The accuracy shield, in such case, is also generally vertically aligned and can be used to contact a solid structure edge, such as the edge of a concrete or blacktop surface, and be guided by the surface so that the edge of the grass bordering on that concrete of blacktop surface is cut in a straight, unwavering line. 
     These and other features and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a conventional weed trimmer with which the present invention can be used; 
         FIG. 2  is a top, plan view of an accuracy shield constructed in accordance with the present invention; 
         FIG. 3  is a side view of the accuracy shield of  FIG. 2  installed on a weed trimmer; 
         FIG. 4  is a bottom view of a debris shield of a weed trimmer; 
         FIG. 5  is a bottom view of the accuracy shield of the present invention installed to a weed trimmer; and 
         FIG. 6  is a side schematic view illustrating the trimmer of the present invention being used as an edger. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , there is shown a conventional weed trimmer  10  for which the present invention is applicable. As can be seen the weed trimmer  10  includes a motor  12  that provides a powered rotational element of the weed trimmer  10 . As such, the motor  12  can be an electric motor powered by a conventional source of electricity made accessible by a power cord, not shown, or the motor  12  can be an internal combustion engine including a supply of fuel so as to be self sufficient. 
     Accordingly, in either event, the motor  12  is shown affixed to a proximal end of an elongated shaft  14  that is hollow and has an element, such as a flexible shaft within the elongated shaft  14  that extends from the motor  12  to provide the rotational movement to a rotating spindle  16  located at the distal end  18  of the weed trimmer  10 . It is noted, that, as previously explained, the motor  12  can also be located at the distal end  18  of the weed trimmer  10 . As other conventional elements, there is normally an on/off switch  20  or other device that allows the starting of the motor  12  by the user. In addition, there may be an intermediate handle  22  to be grasped by the hand of the user to aid in the manipulation of the distal end  18  of the weed trimmer  10 . 
     Also, at the distal end  18  of the weed trimmer  10  is a housing  24  that partially surrounds the rotating spindle  16  and a portion of the housing may have a downwardly extending debris shield  26  to protect the user from being struck and potentially injured by cuttings, stones or other debris from being projected toward the user during the cutting operation. 
     A line  28  extends outwardly from the rotating spindle  16  and which rotates along with the rotating spindle  16  to actually carry out the cutting process. In addition, there is a line cutter  30  that is affixed to the housing  24  and which cuts off any portion of the radius of the line  28  that would extend beyond the line cutter  30 . As such, when the user strikes or bumps the rotating spindle  16  on the ground to release additional line, the line extends outwardly a finite length and any excess extending outwardly beyond the line cutter  30  is trimmed off by the line cutter  30 . 
     Turning now to  FIG. 2 , taken along with  FIG. 1 , there is shown a top, planar view of the accuracy shield  32  constructed in accordance with the present invention. The accuracy shield  32  can be formed of a plastic, such as acrylics plastic, Lucite or other relatively rigid plastic material. In an exemplary embodiment, the accuracy shield  32  can be transparent and have a thickness of about ¼ inch, however, other thicknesses can be used. 
     Geometrically the accuracy shield  32  has a large, generally circular section  34  that is dimensioned to have a radius just shorter than the length of the line  28  that rotates with the rotating spindle  16 , that is, the tip of the rotating line  28  extends beyond the radius of the large, generally circular section  34 . There is a further larger radius section  36  where the radius is larger than the radius of the large, generally circular section  34 . There is also at least one tab  38  that extends outwardly from the larger radius section  36  for a purpose that will be later described. A notch  39  is also formed in the accuracy shield  32  in order for a line cutter  30  to pass through the accuracy shield  32  and to cut the line  28  as will be later explained. 
     The accuracy shield  32  has a center opening  42  with a center point  40  as its center, and which surrounds and is slightly larger than the outer diameter of the rotating spindle  16  so as to, when installed, surround the rotating spindle  16 . 
     To explain the particular geometry of the accuracy shield, the larger radius section  36  has a diameter A that is basically the amount of line released at one line release (bump) subtracted from the distance from the center point  40  to the position of the line cutter, that is, if the distance from the centerline of the line head to the line cutter is 10 inches and the rotating spindle releases 2 inches per bump, the A dimension would be 16 inches or a radius of 8 inches. The dimension B is the size or diameter of the rotating spindle  16  plus ¼ inch for clearance around the rotating spindle  16 . The C dimension is about ⅝ inch for the tab  38  used to retain the accuracy shield  32  in position affixed to the debris shield  26 . Finally, the dimension D is about 2 inches larger on both sides of the actual debris shield provided with the weed trimmer  10 . 
     Turning now to  FIG. 3 , taken along with  FIGS. 1 and 2 , there is shown a side view of the accuracy shield  32  affixed in place to the weed trimmer  10 . In  FIG. 3 , the debris shield  26  is to the left and, as can be seen, the tab  38  of the larger radius section  36  fits through a slot  44  formed in the debris shield  26  so that the interfitting of the tab  38  into the slot  44  forms a support for affixing the accuracy shield  32  to the housing  24 . Other devices to secure the accuracy shield  32  can be L-shaped brackets  46 , only one of which is shown are shown in  FIG. 3 . 
     Thus, the line  28  rotates along with the rotating spindle  16  and the accuracy shield  32  is located between the rotating line  28  and the housing  24 . In an exemplary embodiment, the line  28  rotates in a plane that is parallel to the plane of the accuracy shield and displaced about ⅜ inch away from that accuracy shield  32 . 
     Turning briefly to  FIG. 4 , there is shown a bottom view of a debris shield  26  having the slot  44  formed therein. 
     Turning next to  FIG. 5 , there is shown a bottom view of the lawn trimmer  10  of the present invention and wherein the L-shaped brackets  46  can be seen to be secured both to the accuracy shield  32  as well as the debris shield  26  so as to secure the accuracy shield  32  thereto. In addition, the tab  38  can be see passing though the slot  44  formed in the downwardly portion of the debris shield  26  so that the accuracy shield  32  can be affixed to the debris shield  26  by the combination of the tab  38  interfitting through a slot  44  in the debris shield  26  as well as by the use of L-shaped brackets  46 . 
     Turning finally to  FIG. 6 , there is a side schematic view illustrating one of the uses of the lawn trimmer  10  of the present invention. As can be seen in  FIG. 5 , the weed trimmer  10  has been oriented such that the plane of rotation of the line  28  as well as the plane of the accuracy shield  32  is generally vertical such that the weed trimmer  10  can be used as a edger to trim the edge of a grass area  48  as it abuts against another area, such as concrete area  50 . As can be seen, the weed trimmer  10  has been oriented such that the plane of the rotation of the line  28  as well as the plane of the accuracy shield  32  are generally vertical. 
     As such, the line  28  can be used to trim the grass area  48  to provide a neat appearance alongside a proximate area, such as the concrete area  50 . In this mode, the accuracy shield  32  provides stability by contacting the side of the concrete area  50  such that the contact between the accuracy guide  32  and the concrete area  50  stabilizes the movement of the line  28  and the ensuing edge has a clean and even appearance. 
     Those skilled in the art will readily recognize numerous adaptations and modifications which can be made to the weed trimmer of the present invention which will result in an improved weed trimmer and method of making and using the same, yet all of which will fall within the scope and spirit of the present invention as defined in the following claims. Accordingly, the invention is to be limited only by the following claims and their equivalents.

Technology Category: 4