Abstract:
A laser calibration device includes a housing and a pendulum pivotally coupled to the housing and suspending downwards therefrom. A laser deck is mounted to the pendulum. At least one laser for emitting a laser line is mounted to the laser deck. The laser includes a laser barrel rotatable within a barrel holder and a laser lens pivotally coupled to the laser barrel. A first adjustment mechanism is mounted between the laser deck and the laser for adjusting pitch. A second adjustment mechanism is mounted between the barrel holder and the laser barrel for adjusting roll. A third adjustment mechanism is mounted between the laser barrel and the laser lens for adjusting crowning. A fourth adjustment mechanism mounted to the pendulum for adjusting a center of gravity of the pendulum.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/544,977, filed on Feb. 13, 2004. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a laser calibration apparatus and method, and more particularly to a laser calibration apparatus and method for a tripod and laser head assembly.  
       BACKGROUND OF THE INVENTION  
       [0003]     A tripod and laser head assembly provides a stable platform for an arrangement of laser diodes to project a number of laser lines therefrom. The lasers can have numerous uses, from surveying to leveling. In the case of leveling, the laser light beam is projected onto the surface of an object in order to provide a perfectly horizontal line thereon. For example, a laser leveler may be employed to hang pictures on a wall evenly, level a joist or beam during construction, or for marking a line.  
         [0004]     Typically, a laser leveler has but a single laser source that projects a single horizontal light beam outwards. Depending on the distance from the laser source to the surface of the object that the light beam is being projected onto, a single laser source can only provide an arc of laser light less than 180°. In practice, this results in a horizontal line projected on the surface of the object that is limited in length. In order to project a visible light line on a surface of an object without a limitation as to line length, for example projecting a continuous light beam on four walls in a square room, more than one laser source must be employed.  
         [0005]     However, calibrating more than one laser source in a single device can be difficult. When leveling or calibrating a laser light beam, in order to provide a truly horizontal line, six adjustment factors must be considered. The first three adjustment factors include an X axis, a Y axis and a Z axis (corresponding to the three movement directions in space). The X, Y and Z directions may be calibrated by adjusting the height of the laser sources for the Z axis, and by using a pendulum to calibrate the X and Y axes. The next three factors of calibration include rotation about the X axis, i.e. roll, rotation about the Y axis, i.e. pitch, and rotation about the Z axis, i.e. yaw. When using a single light source, roll, pitch and yaw may be adjusted by simply adjusting various parts of the laser light source. However, when utilizing a plurality of light sources, adjusting the roll, pitch and yaw is more difficult.  
         [0006]     Accordingly, the present invention seeks to provide a laser calibration apparatus useful for a plurality of laser light sources and a method of calibrating the plurality of laser light sources.  
       SUMMARY OF THE INVENTION  
       [0007]     A laser calibration device includes a housing and a pendulum pivotally coupled to the housing and suspending downwards therefrom. A laser deck is mounted to the pendulum. At least one laser for emitting a laser line is mounted to the laser deck. The laser includes a laser barrel rotatable within a barrel holder and a laser lens pivotally coupled to the laser barrel. A first adjustment mechanism is mounted between the laser deck and the laser for pivoting the laser with respect to the laser deck to adjust a pitch of the laser line. A second adjustment mechanism is mounted between the barrel holder and the laser barrel to rotate the laser barrel with respect to the barrel holder to adjust a roll of the laser line. A third adjustment mechanism is mounted between the laser barrel and the laser lens to pivot the laser lens with respect to the laser barrel to adjust a crowning of the laser line. A fourth adjustment mechanism mounted to the pendulum for adjusting a center of gravity of the pendulum. The first, second, third, and fourth adjustment mechanisms are used to make horizontal the laser line emitted from the laser.  
         [0008]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0010]      FIG. 1  is an isometric view of an exemplary laser tripod assembly having a laser calibration apparatus constructed according to the principles of the present invention;  
         [0011]      FIG. 2  is an isometric view of the housing of the laser calibration apparatus of the present invention;  
         [0012]      FIG. 3  is a cross-sectional view of the housing in  FIG. 2  taken in the direction of arrow  3 - 3 , illustrating the laser calibration apparatus of the present invention located therein;  
         [0013]      FIG. 4  is an isometric view of the laser calibration apparatus of the present invention;  
         [0014]      FIG. 5  is an isometric view of a single laser light source used in combination with the laser calibration apparatus of the present invention; and  
         [0015]      FIG. 6  is an isometric view of the single laser light source of  FIG. 5  in a disassembled configuration. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0017]     With reference to  FIG. 1 , a laser calibration apparatus  10  is illustrated in association with an exemplary laser tripod assembly  12 . The laser calibration apparatus  10  and the associated method is used to calibrate a plurality of laser sources, as will be described in greater detail below, such that the laser tripod assembly  12  may be used to project a horizontal continuous laser line onto a given surface. The laser tripod assembly  12  generally includes a laser head  14  removably attached to an expandable neck  16  extending from a tripod base  18 . The tripod base  18  includes a plurality of legs  20 . A detailed description of this exemplary laser tripod assembly  12  may be found in commonly assigned co-pending application Ser. No. 10/979,953.  
         [0018]     Turning now to  FIG. 2 , the laser head  14  includes a housing  22  used to protect the laser calibration apparatus  10  ( FIG. 1 ) located therein. A plurality of windows  24  are formed in a top portion of the housing  22  to allow the laser sources located therein to emit laser beams from the laser head  14 .  
         [0019]     With reference to  FIG. 3 , the laser calibration apparatus  10  is illustrated in operative association with the laser head  14 . The laser calibration apparatus  10  generally includes a pendulum  26 , a laser deck  28  mounted to the pendulum  26  and a plurality of laser sources  30  mounted to the laser deck  28 .  
         [0020]     The pendulum  26  includes a long shaft  32  extending between a pivot point  34  located at an end thereof and a weighted magnet  36 , located at an opposite end of the shaft  32 . The pivot point  34  is rotatably connected to a top portion  38  of the housing  22  in the laser head  14 . The pivot point  34  allows the pendulum  26  to move in the X and Y directions (as indicated in  FIG. 4 ). The weighted magnet  36  acts to keep the shaft  32  perpendicular to a perfectly horizontal line. The weighted magnet  36  engages a metal contact  40  mounted to the housing  22 . The metal contact  40  may be moved by engaging a switch (not shown) such that the end of the pendulum  26  with the weighted magnet  36  may move freely. When the metal contact  40  is moved back into its engaged position (as shown in  FIG. 3 ), the weighted magnet  36  engages the metal contact  40 , thereby keeping the pendulum  26  from rotating about the pivot point  34 . The metal contact  40  is used to keep the pendulum  26  from moving when the laser tripod assembly  12  is being transported, thereby preventing the laser calibration apparatus  10  from moving during transport.  
         [0021]     With reference to  FIG. 4 , the laser deck  28  is mounted to the shaft  32  of the pendulum  26  near the pivot point  34 . There is one laser deck  28  for each of the laser sources  30 . In a particular example provided, there are three laser sources  30  and, accordingly, three laser decks  28  (only two of which are visible). However, fewer or more than three laser sources  30  and three laser decks  28  may be employed with the present invention. Each laser source  30  has a calibration position that is defined by six degrees of movement including an X axis, a Y axis, a Z axis, rotation about the X axis (roll), rotation about the Y axis (pitch), and rotation about the Z axis (yaw).  
         [0022]     The laser deck  28  extends perpendicularly outward from the shaft  32 . The laser deck  28  has a lower surface  42  with a groove  44  formed therein. As will be described in greater detail below, the groove  44  is used to allow a laser source  30  to pivot at that point, thereby adjusting pitch.  
         [0023]     The laser deck  28  further includes a top surface  46  located above the laser source  30 . The top surface  46  extends the length of the laser source  30  and is mounted to the pendulum  26 . There is a top surface  46  for every laser source.  30 . The top surface  46  includes a pitch screw  48  extending therethrough at one end of the top surface  46  and a biasing member  50  extending from the top surface  46  towards the laser source  30  at the opposite end of the top surface  46  from the pitch screw  48 . As will described in greater detail below, the pitch screw  48  and the biasing member  50  act to adjust the pitch of the laser source  30 .  
         [0024]     Turning now to  FIGS. 5 and 6 , one of the laser sources  30  will now be described in greater detail. The laser source  30  includes a barrel holder  50 , a laser barrel  52  and a lens holder  54 . The barrel holder  50  includes an opening  56  sized to receive the laser barrel  52  therein. The opening  56  is formed on a front face  58  of the barrel holder  50 . A slot  60  extends from the opening  56  onto a top surface  62  of the barrel holder  50 . The slot  60  is sized to receive a portion  70  of the laser barrel  52 , as will be described below. The barrel holder  50  also includes a rib  64  formed on a bottom surface  66  thereof. The rib  64  is sized to fit within the groove  44  ( FIG. 4 ) of the laser deck  28 .  
         [0025]     The laser barrel  52  houses a laser diode (not shown) that generates the laser beam used in the invention. A vertical fin  70  extends up from the laser barrel  52 . The vertical fin  70  is sized to fit within the slot  60  of the barrel holder  50  when the laser barrel  52  is inserted into the opening  56 . The laser barrel  52  further includes a pair of grooves  72  and a screw mount  74  formed on an end of the laser barrel  52  for receiving portions of the lens holder  54 .  
         [0026]     Lens holder  54  includes a lens  76  mounted therein used to focus the laser beam generated from the laser diode (not shown) in the laser barrel  52 . The lens holder  54  includes a pair of tabs  78  sized to fit within the groove  72  of the laser barrel  52 . The tabs  78  secure the lens holder  54  onto the laser barrel  52 .  
         [0027]     The laser source  30  includes two adjustment devices used to calibrate the laser source  30  including a roll screw  80  and a crown screw  82 . The roll screw  80  fits within screw holes formed in the barrel holder  50  and the vertical fin  70  of the laser barrel  52 . As will be described below, adjusting the roll screw  80  in turn moves the fin  70  thereby adjusting the laser barrel  52  relative to the barrel holder  50 . The crown screw  82  fits within screw holes in the lens holder  54  and the screw mount  74  of the laser barrel  52 . As will be described below, adjusting the crown screw  82  adjusts the crowning effect of the laser emitted through the lens  76  of the lens holder  54 .  
         [0028]     With general reference to  FIGS. 4, 5 , and  6 , the calibration of the laser calibration apparatus  10  will now be described. First, one of the laser sources  30  is selected and activated such that a laser beam is being emitted from the selected laser source  30  onto an object thereby creating a laser line. Then, the crown screw  82  of the selected laser source  30  is adjusted to eliminate any crowning in the laser line (e.g., removing any arc in the laser line such that it is straight). Adjustment of the crown screw  82  moves the lens holder  54  relative to the laser barrel  52  since the tabs  78  keep the lens holder  54  secured at a top of the lens holder  54 .  
         [0029]     Next, the roll screw  80  of the selected laser source  30  is used to adjust the laser line to a horizontal plane. Adjusting the roll screw  80  moves the vertical fin  70  and in turn the laser barrel  52  relative to the barrel holder  50 . Once the selected laser source  30  has been adjusted using the crown screw  82  and the roll screw  80  to create a straight horizontal line, each of the other plurality of laser sources  30  are then similarly adjusted using the crown screw  82  and the roll screw  80 . At this point the laser lines emitted from all of the laser sources  30  are straight and horizontal. However, each laser line may not be in alignment, or in the same plane, as the next.  
         [0030]     Next, the pitch screws  48  for each laser source  30  are adjusted such that each of the laser lines emitted from the laser sources  30  are all on the same plane (e.g., each laser line is in alignment with one another) thereby forming a “laser plane”. The laser plane should be straight and continuous, although not necessarily horizontal. Since the biasing members  50  bias an end of the laser sources  30  away from the top surfaces  46  of the laser decks  28 , by adjusting the pitch screws  48  the laser sources  30  are forced to pivot about the ribs  64  and grooves  44  until such time that the laser sources  30  are planar with one another.  
         [0031]     In order to bring the laser plane to a horizontal plane, the pendulum  26  is allowed to swing freely such that the shaft  32  of the pendulum  26  is completely vertical. The laser lines of the laser sources  30  are straight and in alignment with one another in the laser plane. However, the laser plane may not be horizontal. Balance screws  84 , located on an end of the shaft  32 , are adjusted to bring the laser plane to a horizontal plane. The balance screws  84  adjust the center of gravity of the pendulum  26  by moving the center of mass of the balance screws  84  closer or farther away from the shaft  32 .  
         [0032]     By using the above method, each of the plurality of laser sources  30  are brought into the same plane and then brought into the horizontal plane. At any point thereafter, the calibration method may be repeated in order to recalibrate the laser sources  30 .  
         [0033]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.