Abstract:
A laser level includes a level-adjusting device and a laser transmitter device mounted on the level-adjusting device. The level-adjusting device includes a horizontal flat board movable by a plurality of motor modules to a desired condition, a cross rotatable circle including an outer circle rotatable about a first rotation axis and a concentric inner circle rotatable about a second rotation axis perpendicular to the first rotation axis, and a connecting post connecting the horizontal flat board to the cross rotatable circle and supporting the laser transmitter thereon.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a laser level, and more particularly to a laser level with improved leveling adjustability.  
         [0003]     2. Description of the Prior Art  
         [0004]     Because of excellent linearity, a laser level is commonly used to measure or verify the horizontality or perpendicularity of an object by emitting and receiving a laser beam. As the cost of laser transmitter decreases ceaselessly, the laser level is getting more and more common in architecture/construction projects or installation of large machines.  
         [0005]     A conventional laser level generally comprises a level-adjusting device and a laser transmitter mounted on the level-adjusting device. The level-adjusting device adjusts the leveling of the laser transmitter whereby the laser transmitter can project a laser beam in a correct direction.  
         [0006]     The level-adjusting device can do direction adjustment in either an active manner or a passive manner. In passive adjustment, leveling adjustment is done by means of gravitation or buoyancy of liquid, while in active adjustment, adjustment of leveling is performed through mechanical driving.  
         [0007]      FIGS. 1-3  of the attached drawings illustrate a conventional level-adjusting device  110  for adjusting leveling of an object  116 , such as a laser transmitter, mounted thereon. The level-adjusting device  110  comprises a base  113 , a plurality of posts  111  extending upright from the base  113 , a mounting plate  112  supported by the posts  111 , a rotatable spherical body  114  mounted in an opening defined in the mounting plate  112 , and a shaft  115  extending through the spherical body  114 , connected to the object  116 , and driven by a motor  118  so as to permit rotation of the object  116  upon actuation of the motor  118 . The shaft  115 , together with the object  116 , is slightly moved relative to a horizontal plane, i.e. the sea level, upon rotation of the spherical body  114  during level adjustment of the object  116 .  
         [0008]     The spherical body  114  is rotated by a transmission unit  200  that comprises a mounting seat  117  connected to the spherical body  114 , a connecting member  201  connected to the mounting seat  117  and having two opposite legs  211 , a first operating rod  208  engageable with one of the legs  211  for driving the connecting member  201  to move in a first horizontal direction and engageable with the other of the legs  211  for driving the connecting member  201  to move in a first opposite direction opposite to the first horizontal direction, and a second operating rod  209  engageable with one of the legs  211  for driving the connecting member  201  to move in a second horizontal direction and engageable with the other of the legs  211  for driving the connecting member  201  to move in a second opposite direction opposite to the second horizontal direction.  
         [0009]     The first and second operating rods  208 ,  209  are mounted slidably on a support  203  through first and second threaded blocks  207 ,  205  and first and second screw rods  206 ,  204 , which engage, threadedly and respectively, the first and second threaded blocks  207 ,  205 . In operation, movement of the first or second operating rod  208 ,  209  or both the first and second operating rods  208 ,  209  results in rotation of the spherical body  114 , which, in turn, results in co-movement of the object  116  and the shaft  115  to the sea level.  
         [0010]     The aforesaid conventional level-adjusting device  110  is disadvantageous in that leveling adjustment of the object  116  is time-consuming. For instance, since the spherical body  114  can only rotate about its center, movement of the first operating rod  208  not only results in movement of the connecting member  201  in the first horizontal direction, but also results in an undesired movement of the transmission member  201  in the second horizontal direction due to rotation of the spherical body  114 , which requires further operation of the second operating rod  209  to adjust leveling of the object  116 , which, in turn, requires further operation of the first operating rod  208 , and so on. As a consequence, the operation is quite time-consuming.  
         [0011]     Hence, an adjusting device is required to overcome the above-mentioned disadvantages of the prior art.  
       SUMMARY OF THE INVENTION  
       [0012]     Therefore, an object of the present invention is to provide a laser level with improved leveling adjustability in order to overcome the aforesaid drawbacks associated with the prior art.  
         [0013]     According to the present invention, there is provided a laser level comprising a level-adjusting device and a laser transmitter device mounted on the level-adjusting device. The level-adjusting device comprises a plurality of motor modules, each selectively driving a block in a vertical direction, and a horizontal flat board supported by the blocks to be set to a desired condition by the movements of the blocks. A cross rotatable circle is arranged above the horizontal flat board, and comprises an outer circle rotatable about a first rotation axis and a concentric inner circle rotatable about a second rotation axis substantially perpendicular to the first rotation axis. Thus, the inner circle is rotatable in two directions with respect to the level-adjusting device. A connecting post couples the cross rotatable circle to the horizontal flat board. The connecting post has an end fixed to the horizontal flat board and an opposite end closely fit in the inner circle and carrying an adjusting flat board that is turn supports the laser transmitter thereon. The rotation of the inner circle in the two directions is independent of each other, whereby adjusting the horizontal flat board by the motor modules results in independent adjustment of the adjusting flat board and thus the laser transmitter in the two directions. A time efficient adjustment can be realized.  
         [0014]     The advantages and novel features of the invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The present invention may best be understood through the following description with reference to the accompanying drawings, in which:  
         [0016]      FIG. 1  is a cutaway view of a conventional level-adjusting device with an object mounted thereon;  
         [0017]      FIG. 2  is a perspective view of a transmission unit of the level-adjusting device of  FIG. 1 ;  
         [0018]      FIG. 3  is a cutaway top view of the transmission unit of the level-adjusting device of  FIG. 1 ;  
         [0019]      FIG. 4  is an exploded perspective view showing of a laser level in accordance with a preferred embodiment of the present invention;  
         [0020]      FIG. 5  is a perspective view of the laser level in accordance with the present invention;  
         [0021]      FIG. 6  is a perspective view of a motor module of the laser level of the present invention; and  
         [0022]      FIG. 7  is a perspective view of a cross rotatable circle of the laser level of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]     Reference will now be made in detail to a preferred embodiment of the present invention.  
         [0024]     Referring to  FIGS. 4 and 5 , a laser level constructed in accordance with the present invention comprises a level-adjusting device  101  and a laser transmitter device  102  mounted on the level-adjusting device  101 .  
         [0025]     The level-adjusting device  101  comprises a support base  1 , two motor modules  2 , two spring  8 , a support post  9 , a horizontal flat board  3 , two level detecting sensors  7 , a plank  4 , a cross rotatable circle  5 , and a connecting post  6 .  
         [0026]     The connect post  6  comprises a cylinder  62 , a circular flat board  61  perpendicularly mounted to one end of the cylinder  62 , and an extension post  63  coaxially extending from an opposite end of the cylinder  62 .  
         [0027]     Also referring to  FIG. 6 , each motor module  2  comprises an upright post  21  in an inside face of which a trough (not labeled) co-extensive therewith is defined. A screw rod  22  is arranged inside the trough and extends in parallel to the post  21 . A motor  23  is coupled to an end of the screw rod  22  for selectively rotating the screw rod  22 . An L-shaped block  25  is movably coupled to the post  21 . The block  25  comprises a mounting portion  251  that is in driving engagement with the screw rod  22  and a support portion  252  extending from the mounting portion  251 . A spherical member, such as a steel ball  24 , is rotatably mounted on an upper surface of the support portion  252 . The rotation of the screw rod  22  caused by the motor  23  selectively moves the block  25  up and down along the screw rod  22 .  
         [0028]     Referring to  FIG. 7 , the cross rotatable circle  5  comprises an annular outer cover  51 , an outer circle  52 , and an inner circle  53  concentric with each other. Extending along a first direction from an inner surface of the outer cover  51  is a pair of diametrically aligned rotary pivots  55 , which will be referred to as “first pivots” hereinafter. The outer circle  52  is rotatably mounted in the outer cover  51  through two bearings  54  that receivingly engage the first pivots  55  to allow the outer circle  52  to rotate about the first pivots  55  inside the outer cover  51 . Extending in a second direction from an inner surface of the outer circle  52  is a pair of diametrically aligned rotary pivots  56 , which will be referred to as “second pivots” hereinafter. The inner circle  53  is rotatably mounted in the outer circle  52  through two bearings  54  receivingly engaging the second pivots  56  to allow the inner circle  53  to rotate about the second pivots  56  inside the outer circle  52 . Thus, the inner circle  53  is rotatable with respect to the outer circle  52  about an axis extending in the second direction defined by the second pivots  56 , and the outer circle  52  is rotatable with respect to the outer cover  51  about an axis extending in the first direction defined by the first pivots  55 . The rotations of the inner circle  53  and the outer circle  52  are independent of each other, whereby the inner circle  53  is rotatable with respect to the outer cover  51  at any desired angular position along both the first and second axes. Preferably, the first axis and the second axis are perpendicular to each other.  
         [0029]     Referring to  FIG. 5 , the two motor modules  2  are mounted on the support base  1  with the upright posts  21  substantially perpendicular to the base  1 . The motor modules  2  are arranged in such a way that the extending directions of the support portions  252  of the blocks  25  are substantially normal to each other. In other words, the motor modules  2  are angularly spaced by about 90 degrees with the troughs thereof facing diametrically inwards. The horizontal flat board  3  is positioned on the support portions  252  of the blocks  25  by contacting the steel balls  24 .  
         [0030]     The level detecting sensors  7  are placed on an upper surface of the horizontal flat board  3  opposite to the two motor modules  2  respectively. The springs  8  are positioned between a bottom surface of the horizontal flat board  3  and the support base  1 . The support post  9  is arranged on the support base  1  at a position that forms a triangle with the two motor modules  2 . That means the support post  9  and the motor modules  2  are apexes of the triangle. The support post  9  and the two motor modules  2  support the plank  4  together. The cross rotatable circle  5  is mounted on the plank  4 .  
         [0031]     The cylinder  62  of the connecting post  6  has an outside diameter substantially corresponding to an inner diameter of the inner circle  53  and is fit into the inner circle  53  with the flat board  63  resting on the cross rotatable circle  5  and a free end of the extension post  63  mounted to the horizontal flat board  3 .  
         [0032]     In operation, the sensors  7  detect the level of the horizontal flat board  3  in the first and second directions. Based on the result of detection by the sensors  7 , the motor  2  drives the blocks  25  to move up and down to adjust the horizontal flat board  3  until the horizontal flat board  3  becomes horizontal. Because of the spring forces induced by the springs  8 , the horizontal flat board  3  is maintained constantly in contact with the steel balls  24  on the blocks  25  and moves up and down in unison with the blocks  25 . The springs  8  also ensure that the blocks  25  are in mating engagement with the screw rods  22 .  
         [0033]     During the adjustment of the horizontal flat board  3 , the connecting post  6  swings with the movement of the flat board  3 . Because the cylinder  62  is closely fit in the inner circle  53  of the cross rotatable circle  5 , the inner circle  53  and outer circle  52  move with the cylinder  62  until the flat board  61  becomes horizontal. Since the inner circle  53  can only rotate about the second pivots  56  and the outer circle  52  can only rotate about the first pivots  55 , the level adjusting is independently in the first and second directions, which can be at any angle with respect to each other and preferably perpendicular to each other. This arrangement helps reducing mutual interference between the two directions and saves adjusting time.  
         [0034]     As the level-adjusting device  101  is adjusted to the horizontal, the laser transmitter device  102  mounted on the level-adjusting device  101  can work horizontally.  
         [0035]     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.