Abstract:
A golf club incorporates a slope indicator on its shaft. to enable a golfer to estimate the slope of a putting green. When the golf club is placed on the ground, the slope indicator indicates a degree of slope. The golfer may engage a lock for the slope indicator. Engagement of the lock allows the golfer to lift the club off the ground to inspect the slope indicator.

Description:
FIELD OF INVENTION 
     The present invention relates to golf clubs and in particular golf putters. 
     BACKGROUND 
     Many golfers have difficulty ‘reading’ a green so as to putt the golf ball to the pin with the correct speed and direction. In particular it may be difficult to assess the slope of the green, especially if the slope is slight or changes direction. 
     What is required is a simple means of determining green slope (if any) so as to allow a novice golfer to improve his game, and to learn to ‘read’ a green. Such a device would be particularly useful as a training aid. 
     There have been other attempts to provide a device for measuring the slope, such as a spirit level. Examples of golf clubs that use a spirit level are found in U.S. Pat. Nos. 5,755,623, 4,179,125, 5,209,470, 5,820,476, 2,919,491, and Great Britain Pat. No. 2318980, each of which are hereby incorporated by reference in their entirety for all purposes. 
     SUMMARY OF THE INVENTION 
     According to the invention there is a golf club that includes a scale for indicating the slope of a putting surface. The scale is preferably located on the shaft envelope, although it could be located along other areas of the golf club, such as a putter. The scale includes a weight balanced arm and a reference line. When the putter is placed on the putting surface, the arm moves relative to the reference line if there is a slope, i.e., inclination, to the putting surface. If there is no slope to the putting surface, then the arm does not move relative to the reference line. 
     The scale may include a cover, for example a slidable door or sleeve, to protect the face thereof from weather and dirt. A cover or sleeve may also be incorporated so that the club may be converted from training mode (scale exposed for use) and competition (sleeve slid over scale so that it cannot be used). 
     The scale may conveniently be incorporated within one component of the golf club, for example the handle, shaft or head, so as to facilitate manufacture and assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features of the invention will be apparent from the following description of a preferred embodiment shown by way of example only in the accompanying drawings in which: 
         FIG. 1  is a perspective view of a putter having a scale disposed on its shaft. 
         FIG. 2  is a side view showing a portion of the putter shaft and a close-up view of the scale of  FIG. 1 . 
         FIG. 3A  is a side view close-up of the scale of  FIG. 1 .  FIG. 3B  is a top, cross-sectional view of the scale as taken from section IV-IV in  FIG. 3B . The scale includes an arm balanced about a rotation axis and a reference line to indicate the degree of rotation of the arm about the rotation axis. 
         FIGS. 4A-4B  are two top views of the scale as taken from section IV-IV in  FIG. 3B .  FIG. 4A  depicts a first, unlocked or free rotation position for the arm and  FIG. 4B  depicts a second, locked position for the arm. 
         FIG. 5  shows a scale with hash marks. 
         FIGS. 6A-6B  shows an alternative embodiment of the scale. According to these embodiments, different colors are used to indicate whether there is a slope to the putting surface. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIG. 1 , there is shown in perspective view a putter  1  with a scale  10  mounted to the putter shaft  2 . The shaft  2  includes a lower end  2   a  that is connected to the putting head  4 , e.g. via a hose  1 . The upper end  2   b  of the shaft  2  receives a grip  7 . 
     Referring to  FIGS. 2-3 , the scale  10  indicates the degree of slope to a green by utilizing a pair of weighted ends  15   a ,  15   b  of a balance arm  14  configured to freely rotated about a shaft assembly  30 . The degree of movement of the arm  14  is appreciated by inspecting the deviation of the arm  14  relative to a fixed reference line  18  formed on the front surface of a backboard or reference surface  30 . the scale  10  may be enclosed in a glass or plastic case  11 . The case  11  may be formed as a diverging convex lens, which magnifies the relative positioning between the arm and reference line  18  for ease of viewing by the golfer. 
     When the putter  1  is placed on the putting surface in the manner shown in  FIG. 2 , i.e., with the reference line  18  extending parallel to the slope of the green and the rotation axis A (see  FIG. 3B ) orientated substantially perpendicular to the vertical, the arm  14  will rotate clockwise or counter clockwise if the slope of the putting surface is at an angle to the horizontal. The degree of slope may then be understood by the angle θ between the reference line  18  and the arm  14 . 
     Regardless of the tilt or slope of the putter, the arm  14  will extend parallel to the horizontal when the arm  14  is balanced about its support point  20 . Thus, in  FIG. 2  the scale  10  indicates the degree of slope of the putting surface based on the difference between the horizontal (arm  14  orientation) and the slope of the green (reference line  18 ). The difference in degree of slope being indicated by the angle θ between line  14  and line  18 . In some embodiments, this perturbation or rotation may be expressed visually to the golfer by simply inspecting the relative locations of the lines  14 ,  18 , by using reference hash marks or reference lines displayed across the surface  30  or placed on the glass/plastic cover  11 , or by using distinguishing colors or patterns (see  FIGS. 6A-6B ). 
     According to another aspect of the disclosure, the scale  10  includes a locking feature that enables a golfer to pick up the putter to inspect the slope depicted on the scale  10 . Referring to  FIGS. 4A-4B , which shows a cross-sectional view of the scale  10  as in  FIG. 3B , the scale includes a shaft  20  about which the arm  14  pivots. The shaft includes a head  21 , a lower end having a knob  24  and a fitting  2   e  that allows shaft to be pulled and pushed up or down, as indicated in  FIGS. 4A-4B . When the knob  24  is pushed upwards as shown in  FIG. 4A , the head  21  is separated from the surface  30  and does not obstruct the rotation of the arm  14 , so that the arm  14  can freely rotate about the shaft  20 . When the head  21  is brought down to abut the surface  30 , as indicated by reference  23  in  FIG. 4B , the head  21  is pulled into abutment with the surface  30  and arm  14 , thereby retraining free rotation of the arm  14 . The knob  24  may be easily pressed towards the shaft opening  2   e , or pulled away from the shaft opening  2   e  to selectively engage/disengage the head  21  from the arm  14  by known methods in the art, e.g., by having a resilient, plastic ledge that engages with a ridge formed on the shaft  26  that selectively positions the head  21  in the locked ( FIG. 4B ) or unlocked position ( FIG. 4A ). This locking feature enables a golfer to pick up the putter to inspect the slope indicated on the scale  10  without disrupting the relative position between the arm  14  and reference line  18 . 
     In use, the golfer would first place the putter  1  on the ground in the manner shown in  FIG. 2  (so that the rotation axis A is about perpendicular to the vertical) and allow the arm  14  to come to rest. Next, the golfer would pull the knob  24  out ( FIG. 4B ) so as to fix the arm  14  in its balance position relative to the reference line  18 . The golfer may then pick up the putter to visually inspect the position of the arm  14  relative to the line  18 . This locking feature can obviate the need for a golfer to have to bend down to an uncomfortable position in order to inspect the scale  10 . 
     Referring to  FIGS. 6A-6B , According to some embodiments, the scale  10  may include hash marks  40  that can be used to inspect the degree of slope, i.e., the amount that the arm  14  has rotated relative to the reference line  18 . According to other embodiments, a scale  50  includes arms  14  which have a first color  52  and are shaped to cover a second color  54  when the putting surface is flat ( FIG. 6A ). When the putter  1  is placed on a sloped surface ( FIG. 6B ), the arm  14  having a first color  52  surface rotates to expose the second color  54 . The first color  52  may be, for example, green and the second color  54  red. 
     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications can be made without departing from this invention in its broader aspects. Therefore, the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit and scope of this invention.