Abstract:
A Prism Tripod includes a planar base including a supported portion and a cantilever portion. Preferably the base includes a cantilever axis, and a point axis, wherein the cantilever axis within the cantilever portion and the point axis within the supported portion. The prism tripod including at least three legs supporting the base and a laser holder for supporting a locating device and a laser. The base is adapted to demountably receive the laser holder along the cantilever axis, wherein the laser and locating device mounted along the cantilever axis.

Description:
[0001]    This application claims priority from previously filed U.S. provisional application 61/328,377 filed on Apr. 27, 2010 by Gerry Clarke under the title Prism Tripod. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present device relates to surveying equipment in particular relates to a device and method for finding points and also for marking points namely a prism tripod and method of use therefore. 
       SUMMARY OF THE INVENTION 
       [0003]    Modern day surveying methods use a robotic total station system in order to determine the location of existing points and also to demark the location of new points to be laid out and marked in the field. 
         [0004]    Presently a prism is generally attached to a handheld post and/or pole, which generally has a pointed end for placement onto the desired location. A robotic total station surveying equipment will generally communicate via the prism to indicate to the user the location of the prism attached to a handheld post or a pole. 
         [0005]    To a certain extent the steadiness of the hand in holding the post or pole on which the prism is mounted can determine the accuracy to which one is able to locate a given point. The users hand will never be totally steady and there will always be some motion and/or swaying of the post or pole on which the prism is located thereby creating a certain margin of error in the location of a specific point which the post or pole is touching. 
         [0006]    In some instances the accuracy required by the engineering and/or architectural specifications is such that the surveyors find it difficult to obtain a quick and accurate location of particular points, which they need to lay out and determine the location of in the field. 
         [0007]    In addition once that point or position is found using the handheld post or pole the surveyor then must in some manner mark or demark the location for future reference by construction personnel. 
         [0008]    In practice often the surveyor will simply scribe or scratch the location of the point by forcibly scratching or scribing the end of the point of the post or pole into the ground, concrete, steel, or other material on which the post or pole is placed. 
         [0009]    The combination of these factors creates a certain amount of uncertainty and error in locating and demarking points to be laid out by the surveyor and at times the accuracy that one is able to obtain using a handheld post or pole onto which a prism is mounted is insufficient in providing the accuracy required by the architectural or engineering specifications. 
         [0010]    Therefore there is a need for a device and method for quickly and accurately locating points, which are already in existence or must be determined. There is a need for a device, which eliminates the variations introduced by the handheld post or pole which is currently used and also provides for a quick and accurate method of locating or demarking a point in the field. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    With the intention of providing demonstration of the characteristics of the device or method, an example is given below, without any restrictive character whatsoever, with reference to the corresponding figures, of a preferred embodiment of the device and method as follows; 
           [0012]      FIG. 1  is a top schematic plan view of a geometrical layout of the elements of the base. 
           [0013]      FIG. 2  is a top schematic plan view of the top surface of the base. 
           [0014]      FIG. 3  is a side perspective schematic elevational view of the prism tripod shown together with a transponder mounted thereon. 
           [0015]      FIG. 4  is a side perspective schematic view of the prism tripod without the transponder mounted thereon. 
           [0016]      FIG. 5  is a side perspective schematic view of the prism tripod together with two prisms mounted on both the prism extension as well as the laser holder. 
           [0017]      FIG. 6  is a schematic bottom plan view of the bottom surface of the base. 
           [0018]      FIG. 7  is a side elevational schematic view of the prism tripod without the transponder attached. 
           [0019]      FIG. 8  is a side perspective view of the laser holder showing the opening  132 . 
           [0020]      FIG. 9  is a side perspective view of the laser together with the wire and switch 
           [0021]      FIG. 10  is a side perspective view of the laser holder together with the laser installed in the opening defined within the laser holder showing the laser in the installed position. 
           [0022]      FIG. 11  is a side perspective schematic elevational view of the prism tripod shown together with a laser holder and a prism mounted thereon along the cantilever axis and adjustable legs with ball ends. 
           [0023]      FIG. 12  is a side perspective schematic elevational view of the prism tripod shown together with a laser holder and a prism mounted thereon along a central axis and adjustable legs with ball ends. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Referring first of all to  FIG. 3 , which shows the prism tripod generally as  100  together with a transponder  118  mounted thereon. Prism tripod  100  includes the following major components namely base  102  having a stationary leg  104 , two adjustable legs  106  each having a thumb screw head  108  for the purpose of manually turning adjustable legs  106 . Stationary leg  104  preferable terminates in a point  124  and also includes a prism extension  110  having a threaded end  140  all extending along point axis  190 . 
         [0025]    Extending along cantilever axis  196  is a laser holder  112  having a threaded end  140  and an opening  132  for receiving a laser  126  therein. Laser  126  also includes a switch  128  in electrical communication with laser  126  with a wire  130 . A laser  126  projects a laser beam  134  terminating at laser point  136  when it impinges upon the desired surface. 
         [0026]    Base  102  further includes a top surface  120 , a bottom surface  122 . Mounted on top surface  120  of base  102  is a set of bubble levels shown as  160  and  162  in  FIG. 2 . 
         [0027]    Base  102  has attached thereto a central post  114  extending along central axis  180  which has a handle  116  and a knob  146  at it&#39;s distal end. 
         [0028]    Shown in  FIG. 3  is a transponder  118  attached to central post  114  with a bracket  150 , which includes a thumbscrew  152 . 
         [0029]    Laser  126  is shown in the installed position  210  housed within an opening  132  of laser holder  112 . 
         [0030]    Additionally adjustable legs  106  are mounted and extend along adjustable leg axis  192  and  194  as shown in  FIG. 1 . 
         [0031]      FIG. 4  shows prism tripod  100  without transponder  118  mounted thereon and without bracket  150  mounted onto central post  114 . 
         [0032]      FIG. 5  shows prisms  142  mounted onto threaded end of prism extension  110  and prism  144  mounted onto threaded end  140  of laser holder  112 . 
         [0033]    In practice a prism would be mounted onto one or the other of threaded ends  140  but usually not two prisms on each end simultaneously.  FIG. 6  is a bottom plan view of the bottom surface  122  of base  102  in particular  FIG. 6  shows laser aperture  220  which is a fine hole through which laser beam  134  is projected in order to display a laser point  136  onto the surface on which it is pointed. 
         [0034]    Referring now to  FIGS. 8 ,  9  and  10 , which show some of the details of laser holder  112  and laser  126 .  FIG. 8  for example shows the laser holder  112  having a housing, which includes an opening  132 . 
         [0035]    Opening  132  is sized to permit placement of laser  126  therein and into the installed position  210  shown in  FIG. 10 . 
         [0036]    Laser  126  includes a wire  130  and a switch  128  for manually turning laser  126  on and off. 
         [0037]      FIG. 1  shows the geometrical relationships between a central axis  180  and point axis  190  adjustable leg axis  192  and adjustable leg axis  194 . 
         [0038]    The circle  122  drawn about central axis  180  will meet tangentially at each of the triangle sides  178  triangle base  176 . Triangle  170  is an isosceles triangle having equi-length triangle sides  178  and triangle base  176 . 
         [0039]    Perpendiculars  174  shown schematically in dashed lines which pass through central access  180  and meet the outer diameter circle  222  at the tangential intersection between circle  222  and the sides of triangle  170  as depicted in  FIG. 1 . 
         [0040]    The reader will note that perpendiculars  174  are in fact normal to each of the triangle sides  178  and triangle base  176  as depicted. 
         [0041]    Referring now to  FIGS. 11 and 12  an alternate embodiment showing prism tripod  300  which includes the following major components namely: base  302  having a top surface  320  and a bottom surface  322 . Base  302  being supported by edge adjustable legs  304  and a corner adjustable leg  305 . Each adjustable leg including thumb screws  317  and lock collars  319  for locking the adjustable legs into position. 
         [0042]    Prism tripod  300  further including the bubble level  356  attached to the top surface  320  for levelling base  302 . Prism tripod  300  also including a central post  314  oriented along central axis  352  and a handle  316  attached to the central post for carrying prism tripod  300 . 
         [0043]    Shown in  FIG. 11  laser holder  312  having mounted thereon prism  344  is shown oriented along cantilever access  350 . Laser holder  312  is almost identical to laser holder  112  as described previously and houses laser  126  therein for creating a laser beam  134  and projecting a laser point  136  along cantilever access  350 . 
         [0044]    As shown in  FIG. 12  laser holder  312  can be positioned in three discreet positions namely along cantilever access  350  as shown in  FIG. 11  along central access  352  as shown in  FIG. 12  and along point access  354  not shown in  FIG. 11  or  12  however shown in  FIG. 5 . 
         [0045]    Normally when laser holder  312  together with prism  344  is mounted along point access  354  corner adjustable leg  305  is replaced with a stationery leg  104  having a point  124  as shown in  FIG. 3 . 
         [0046]    In  FIGS. 11 and 12  the adjustable legs  304  and corner adjustable legs  305  are shown with ball ends  306 . It is possible to use any combination of leg end including pointed ends as shown in  FIG. 3  for example and/or a combination of ball ends  306  together with a pointed end  124 . 
         [0047]    For example edge adjustable legs  304  could be fitted with ball ends  306  and corner adjustable leg  305  could be fitted with point  124  or corner adjustable leg  305  could be completely replaced with a stationary leg  104  having a point  124  as shown in  FIG. 3 . 
       In Use 
       [0048]    Referring to the prism tripod  300  shown in  FIGS. 11 and 12  it is apparent to a person skilled in the art that laser holder  312  together with prism  344  can be placed in three discreet positions including along cantilever access  350  along central access  352  and also along point access  354 . 
         [0049]    Base  302  includes a cantilever corner  360  which allows one to position base  302  over a point which one is wanting to lay out. 
         [0050]    In other words should a surveyor wish to lay out a new point one would normally place laser holder  312  together with a prism  344  along cantilever access  350  such that the laser  126  can project a laser beam  134  and mark a laser point  136  in the desired location. 
         [0051]    On the other hand if one is looking to determine the location of a pre-existing point one would rather place laser holder  312  along point access  354  and one would likely replace corner adjustable leg  305  with a stationary leg  104  having a point  124 . In this manner one could place point  124  onto the pre-existing point and determine it&#39;s location. 
         [0052]    There is the other third configuration for prism tripod  300  namely laser holder  312  together with prism  344  could be installed along central access  352 . In this configuration one could lay out a point which falls in between the adjustable legs such as laying out points within circular tubes and other geometrical configurations which are much easier completed by placing laser holder  312  and prism  344  along central access  352 . 
         [0053]    The reader will note that base  302  includes an unsupported cantilever portion  360  and a supported portion  361 . Supported portion  361  is defined by the area within triangle  170 . The unsupported portion is defined by the area outside triangle  170  and includes the cantilever portion  360  shown in  FIG. 12  and also in  FIG. 1 . Base  302  also includes other cantilever portions which are the portions outside of triangle  170  as shown in  FIG. 1 . These other cantilever portions are not used in the presently preferred embodiment however could be used for other locations of laser holder  312  and prism  344 . 
         [0054]    The reader will note that prism  344  which is alocating device could also include a GPS unit and/or a back sight or any other surveying type of locating device for demarcation layout and/or location of points. In this specification locating device refers to surveying instruments such as prisms, GPS&#39;s, back sights and the like. 
         [0055]    Laser  126  is adapted to project a laser beam  134  downwardly shown as lower beam  393  and also upwardly shown as upper beam  391 . This beam can be projected upwardly and downwardly simultaneously or independently. 
         [0056]    A surveyor using the prism tripod  100  or  300  as described above and depicted above will note immediately that it eliminates the need for hand holding of a prism pole and/or post. Tripod  100  and  300  operate in analogous fashion with some small differences which are discussed. 
         [0057]    The prior art device is very similar to the stationery leg  104  together with the prism extension  110  and a prism  142  mounted thereon. The present device the prism tripod  100  rigidly attaches the components of a typical prism holding rod and/or post onto base  102  as shown in the figures in particular  FIGS. 3 and 5 . By ensuring that prism extension  110 , stationery leg  104  having point  124  and prism  142  are carefully aligned along point axis  180  always ensures that prism  142  is aligned above point  124 . For example should the surveyor wish to determine the location of a particular point which has already been demarked in the field the surveyor could simply place point  124  of prism tripod  100  onto the demarked point and level base  102  using thumbscrew heads  108  which screwably right raise and lower adjustable legs  106  until such time as the user can visually see that base  102  is level according to bubble level  162  and bubble level  160 . Once point  124  is placed onto the demarked point and adjustable legs  106  are adjusted such that base  102  is level the user can then use the robotic total station to determine the location of prism  142  which in turn will tell the surveyor the exact location upon which point  124  is resting. Movement due to hand holding of a prism post and/or pole has been totally eliminated and errors in the location of a demarked point has been minimized. 
         [0058]    On the other hand if a surveyor is seeking to lay out a particular point and mark the position of the point, the surveyor will place prism  144  on to the top of laser holder  112  namely onto threaded end  140 . Laser holder  112  and prism  144  will be aligned along cantilever axis  196  therefore ensuring that wherever the laser beam  134  projects a laser point  136  it is in alignment with the prism  144 . 
         [0059]    In this manner the surveyor can manipulate prism tripod  100  until such time as a robotic total station will tell the user that prism  144  is directly above the desired location. The surveyor can then turn on laser point  136  by depressing switch  128  and thereby laser beam  134  will exactly impinge upon and mark with a laser point  136  the location of the point, which the surveyor wishes to demark. 
         [0060]    The surveyor can then either use a stamp, ink, line, and/or any other marking tool to very accurately mark the location of laser point  136  which is the point that has been laid out by the surveyor. 
         [0061]    In this process of course the user of prism tripod  100  will have levelled base  102  ming thumbscrew heads  108  thereby screwably raising and lowering adjustable legs  106  until such time as base  102  is level as indicated by bubble levels  160  and  162 . 
         [0062]    It will be apparent to the reader that it is very simple and easy to demark a point in that even when a demarking tool such as a stamp or a pen or an ink line or a scribe is placed on the point one can visually determine very accurately that the mark being made is exactly at the point that has been surveyed. Additionally one is able to visually detect the location of the demarcation that has been made as either a scratch or an ink mark, after the mark has been made by ensuring that the laser point is directly on top and shines onto the mark that has been placed by the surveyor. 
         [0063]    It should be apparent to persons skilled in the art of various modification and adaptations of the structure described above are possible without departure from the spirit of the invention the scope of which is defined in the appended claims.