Abstract:
An optical axis adjusting mechanism disposed on a laser ruler for adjusting an optical axis of the laser ruler is provided. The laser ruler includes a main bracket. The optical axis adjusting mechanism includes a main body rotatably assembled to the main bracket of the laser ruler with a shaft, and one or more adjusting elements for selectively rotating the main body about the shaft to adjust an optical axis of the laser ruler.

Description:
BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical axis adjustment device. More specifically, the present invention relates to an optical axis adjustment device that can properly determine a distance between the viewer and a target object. 
   2. Description of the Prior Art 
   A laser ruler is a laser based distance-measuring device, which is an important tool for measuring a distance in the modern industry. The laser ruler operates by measuring a time period in which a laser pulse or laser pulse sequence travels from a laser transmitter to a target object and travels back from the target object to a laser receiver. The distance between the laser ruler and the target object can be obtained by multiplying half of the time period by light speed. An example of the conventional laser based distance-measuring equipment, such as the laser ruler, is disclosed in Taiwan Patent No. 417783, comprising a laser transmitter, a laser receiver perpendicular to the laser transmitter, a prism (or a reflective lens) disposed in front of the laser transmitter on the progressing path of a laser beam transmitted from the transmitter, for reflecting the transmitted laser beam toward the target object. Theoretically, laser beam reflected from the target object is parallel to the optical axis and is received by the laser receiver. By calculating the time period of traveling, a precise distance value is obtained. However, in fact, because the distance between the target object and the laser distance-measuring equipment is finite, a certain included angle between the optical axis of the transmitted laser beam toward the target object and that of reflected laser beam from the target object exists, resulting in an error in distance calculation. In order to avoid the error, position or angle calibration for the prism or the laser transmitter to make the reflected laser beam exactly aiming the center of the laser receiver is required. This indicates that the optical axis of transmitted laser beam reflected by the prism and that of laser beam reflected from the target object exactly intercrosses at the point of target object. Meanwhile, keeping the axis of the transmitted laser beam and that of received laser beam in the same spatial plane is essential. 
   A conventional adjustment mechanism for use in laser distance-measuring equipment, disclosed in Taiwan Patent No. 417783, comprises a first connecting portion disposed on the main body of the laser distance-measuring equipment, a second connecting portion disposed on the laser transmitter, a pair of bolts disposed between the first connecting portion and the second connecting portion. The second connecting portion is movably engaged with the first connecting portion by using a bolt. In doing so, depending on actual measurement condition and environment, a vertical and horizontal position of the second connecting portion relative to the first connecting position is adjusted by using the bolt, achieving the goal of adjusting the laser distance-measuring equipment. However, it is necessary to install a bolt at the both sides of the laser distance-measuring equipment (as shown in FIG. 5 in Taiwan Patent No. 417783), leading to a larger size of the laser distance-measuring equipment, especially in width, and inconvenience for carrying. Furthermore, the adjustment mechanism can simply calibrate one direction, not meeting the reality requirement for precision measurement in various condition and environment. Therefore, it is necessary to provide an adjustment mechanism for calibrating 3-dimension direction of the laser distance-measuring equipment and capable of reducing the size of the laser distance-measuring equipment, to meet a tendency of size-miniaturizing and high precision for such equipment. 
   SUMMARY OF INVENTION 
   It is therefore an object of the present invention to provide an optical axis adjustment mechanism for use in a laser ruler, to miniature the size of the laser ruler. 
   Briefly described, the present invention discloses an optical axis adjusting mechanism disposed on a laser ruler for adjusting an optical axis of the laser ruler. The laser ruler comprises a main bracket. The optical axis adjusting mechanism comprises a main body rotatably assembled to the main bracket of the laser ruler with a shaft, and one or more adjusting elements for affixing the main body to make the main body rotating around the shaft to adjust the optical axis. 
   According to the claimed invention, an optical axis adjusting mechanism installed on a laser ruler is disclosed. The laser ruler comprises a secondary bracket with a sink. The optical axis adjusting mechanism comprises a first body accommodated within the sink, comprising a reflection element for conducting the laser beam toward the laser transmitter, a second body rotatably assembled on the secondary bracket of the laser ruler, the second body being rotatably and movably assembled with the first body, a first adjusting element for applying a torque on the second body along a direction of the optical axis of the received light beam, thereby the second body rotating with respect to the secondary bracket, a second adjusting element for applying a torque on the first body along the direction of the optical axis of the received light beam, thereby the first body rotating with respect to the second body, and a third adjusting element disposed between the first body and the second body, for adjusting a distance between the first body and the second body by moving the first body. 
   According to the claimed invention, an optical axis adjusting mechanism disposed on a laser ruler for adjusting an optical axis of a laser beam from the laser ruler comprises a secondary bracket, disposed on the laser ruler having a supporting plane, a main body, rotatably assembled to the supporting plane with a shaft and through an opening thereon, the main body comprising a laser transmitter, and an adjusting element, for generating a torque applied on the main body to drive the main body rotate with respect to the secondary bracket. 
   These and other objects of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  shows a perspective view of a laser ruler according to the present invention. 
       FIG. 2  is an exploded view of a first optical axis adjusting mechanism of the laser ruler according to the present invention. 
       FIG. 3  shows an assembled view of the first optical axis adjusting mechanism shown in  FIG. 2 . 
       FIG. 4  illustrates an exploded view of a second optical axis adjusting mechanism of the laser ruler according to the present invention. 
       FIG. 5  shows an assembled view of the second optical axis adjusting mechanism shown in  FIG. 4 . 
       FIG. 6  shows a cross-sectional view of the laser ruler taken along line VI—VI of  FIG. 1 . 
   

   DETAILED DESCRIPTION 
   With reference to  FIGS. 1 and 6 , a laser ruler according to the present invention comprises a main body  1 , a first optical axis adjusting mechanism  2  for adjusting the optical axis of a transmitted laser beam and a second optical axis adjusting mechanism  3  for adjusting the optical axis of a received laser beam, an optical shutter  4 , a reflection element  5 , and a laser receiver  6 . The main body  1 , which is substantially rectangular, comprises a secondary bracket  10 , a second portion  11  and a third portion  12 , both being larger in volume than the secondary bracket  10 . The secondary bracket  10  has a sink  101  for accommodating the first optical axis adjusting mechanism  2 . A notch  103  is defined in first and second side walls  102 ,  104  of the sink  101 . Two shaft holes  105  are respectively formed in the first sidewall  102  on opposite sides of the notch  103 . 
   Referring to  FIG. 2 , the first optical axis adjusting mechanism  2  comprises a first body  20 , which is substantially a trapezoid block having an inclined side and a vertical side substantially perpendicular to long and short edges of the trapezoid, and a second body  21 . A reflection element  5  (shown in  FIG. 6 ) an inclined surface  201  defined by the inclined side of the first body  20 . A groove  202  is defined in and co-extends with the long edge of the first body  20 . Two shaft holes  204  are defined in the middle of two side walls  203  of the groove  202 . The second body  21  comprises a main beam  211  in which an inner-threaded hole  2110  is defined, a sub-beam  212  located at an outer end of the main beam  211  and perpendicular to the main beam  211 , and a first positioning block  213  integrally formed with an inner end of the main beam  211 . The sub-beam  212  comprises a first end portion  2121 , which is substantially rectangular, and an opposite second end portion  2122 . A shaft hole  2123  extends through the first end portion  2121  in a direction substantially parallel to the extended direction of the main beam  211 . The second end portion  2122  defines a through, inner-threaded hole  2124 . A second positioning block  214  is extended out of a recess  2125  that is formed in the middle of the sub-beam  212 . An inner-threaded hole  2140  is set through the second positioning block  214 . In addition, a space  215  is delimited between the first positioning block  216 , the sub-beam  212 , and the second positioning block  214  for accommodating a connecting member  22 , which has constructed as a column. The connecting member  22  defines an inner-threaded hole  221 , which corresponds in position to the inner-threaded hole  2110  of the main beam  211 , and a shaft hole  222 . 
   Referring to  FIGS. 2 and 3 , a bolt  23  engages and extends through the inner-threaded hole  2110  and into the corresponding inner-threaded hole  221  of the connecting member  22 , so as to couple the connecting member  22  to the second body  21 . The connecting member  22  is received in the groove  202  with the shaft hole  222  aligning with the shaft holes  204  of the first body  20 . A shaft  29  extends through and engages with both the shaft hole  222  and the shaft hole  204  of the first body  20  to affix the first body  20  to the connecting member  22 . In this way, the distance between the first body  20  and the second body  21  can be adjusted by means of the bolt  23 . Furthermore, a bolt  25  engages with and extends through the inner-threaded hole  2140  of the second positioning block  214  and a lower end of the bolt  25  engages the bottom surface  205  of the groove  202 , whereby by adjusting a length of the bolt  25  protruding out of the second positioning block  214 , the first body  20  is rotated around the shaft  29 , which leads to movement of certain portions of the first body along y-axis, as shown in  FIG. 3 . Moreover, the first positioning block  213  extends into the groove  202  and engages side walls  203  to prevent movement of the first body  20  relative to the second body  21  along x-axis. A spring  26  is disposed at the bottom of the first positioning block  213 , and has one end connected to the first positioning block  213  and the other end connected to the bottom surface  205  of the groove  202 , for providing resiliency.  FIG. 3  shows first optical axis adjusting mechanism  2  in a completely assembled condition. 
   The first end portion  2121  and the second end portion  2122  of the first optical axis adjusting mechanism  2  shown in  FIG. 3  are respectively assembled with the first side walls  102 ,  104  of the secondary bracket  10  shown in  FIG. 1 . The first end portion  2121  and the second end portion  2122  of the first optical axis adjusting mechanism  2  are respectively received in the notches  103  defined in the first and second sidewalls  102 ,  104 , and a shaft  28  extends through the shaft holes  105  and the shaft hole  2123  on the sub-beam  212 . Thus, the second body  21  is rotatably assembled with the main body  1 . As illustrated in  FIGS. 1 and 6 , a bolt  24  engages with and extends through the inner-threaded hole  2124  of the second body  21  and further engages with the first side wall  104  of the main body  1 . In addition, a spring washer  27  located between the second end portion  2122  of the second body  21  and the second wall  104  serves as a buffer. It is noted that, in the preferred embodiment, the bolt  24  and the shaft  28  are perpendicular to each other but are located in different spatial planes. In this way, by using the bolt  24 , a torque is applied on the second body  21  so that the second body  21  and the first body  20  can be rotated around the shaft  28 , to adjust the movement of the first body  20  along x-axis. 
   Referring to  FIG. 4 , the second optical axis adjusting mechanism  3  comprises a transmitting element body  30 , a body main bracket  31 , a connecting body  32 , and bolts  34 ,  35 ,  36 , and  37 . The transmitting element body  30  shaped as a cylinder in which a laser light resource, such as laser diode (not shown in  FIG. 4 ), is fixed. The cylindrical transmitting element body  30  is coupled to the body main bracket  31  by means of the connecting body  32 . The body main bracket  31  comprises a first bottom bar  311  with inner-threaded holes  3111 ,  3112 , a second bottom bar  312  with inner-threaded holes  3121  (only one visible in  FIG. 4 ), and a supporting board  310  which is perpendicular to and fixed between the first bottom bar  311  and second bottom bar  312 . The supporting board  310  forms an opening  3101  corresponding in size and shape to the transmitting element body  30 . A protrusion  3102  projects from the supporting board  310  and forms a shaft hole  3103 . The connecting body  32  comprises a base  320  in which a shaft hole  324  extends and a ring  321  integrally formed with the base  320 . The ring  321  has an inner radius identical to outer radius of the cylindrical transmitting element body  30  and also corresponds to an inner radius of the opening  3101 . The transmitting element body  30  extends through the ring  321  and the opening  3101  of the body main bracket  31 . A connecting end  322  that defines a U-shaped retaining slot  323  is extended out of the base  320 . 
   As shown in  FIG. 4 , the transmitting element body  30  extends through the ring  321  and the opening  3101  of the supporting board  3101 , and the shaft  33  extends through the shaft hole  324  and the shaft hole  3103  of the supporting board  310 , to attach the transmitting element body  30  to the body main bracket  31 . In addition, a bolt  34  encompassed with a spring  38  is received in the retaining slot  323  and engages with the inner-threaded hole  3111  of the first bottom bar  311 , and the bolts  35 ,  36 ,  37  engage with corresponding inner-threaded holes  3121 ,  3112 , the second optical axis adjusting mechanism  3  is assembled as shown in  FIG. 5 . 
   The second optical axis adjusting mechanism  3  as shown in  FIG. 5  is received in the second portion  11  and a spring washer  39  is arranged to provide buffering between the second optical axis adjusting mechanism  3  and the second portion  11 . It is noted that the bolt  34  and the shaft  33  are arranged on different spatial planes, and in the preferred embodiment, the bolt  34  and the shaft  33  are perpendicular to each other but are located on different spatial planes. In this way, the bolt  34  in cooperation with the spring  38  can rotate the connecting body  32  and thus the transmitting element body  30  about the shaft  33 . Thus, with the aid of bolt  35 , an adjustment of the optical axis of the second optical axis adjusting mechanism  3  can be done by using the bolt  34 . An initial position of the transmitting element body  30  can be adjusted by using the bolts  36 ,  37 . 
   As illustrated above, the present invention provides a first optical axis adjusting mechanism  2  for adjusting the optical axis of transmitted laser beam and a second optical axis adjusting mechanism  3  for adjusting the optical axis of the received laser beam. The main body  1  of the laser ruler comprises a secondary bracket  10 , a body main bracket  31 , a first optical axis adjusting mechanism  2 , and a second optical axis adjusting mechanism  3  (having a second body  21 , a connecting body  32 , and a transmitting element body  30 ) rotatably assembled with the secondary bracket  10  and the body main bracket  31 . By using the bolts, the optical axis adjusting mechanism can be rotated with respect to the laser ruler, achieving the goal of adjusting the optical axis. 
   In detail, referring back to  FIGS. 1 and 3 , position (in the z-axis) of the first body  20  of the first optical axis adjusting mechanism  2  relative to the second body  21  can be adjusted based on an adjustment of the bolt  23 . In another aspect, an angular displacement of the second body  21  together with the first body  20  around the shaft  28  can be adjusted based on movement of the bolt  24 , to achieve an angle calibration with respect to the x-axis for optical axis adjusting mechanism  2 . In addition, an angular displacement of the first body  20  around the shaft  29  can be adjusted based on movement of the bolt  25  and the resilience of the spring  26 , to achieve an angle calibration with respect to the y-axis for the optical axis adjusting mechanism  2 . 
   As illustrated in  FIG. 6 , using such adjustment mechanism, the position and the angle of the reflection element  5  can be calibrated to exactly reflect the incident laser into the laser receiver  6 , depending on different condition and environment. It is noted that the preferred embodiment of the present invention utilizes the bolts  24 ,  25  in cooperation with the shafts  28 ,  29  to rotatably adjust the direction of the optical axis, in contrast to the prior art, a size reduction of the laser ruler due to a less amount of bolts requirement, facilitating the design of size reduction. Besides, because the bolts  23 ,  24 ,  25  are positioned from the direction of incident laser beam (i.e. z-axis). That is, the bolts are all located at the same side of the laser ruler, which reduces the amount of space required by the optical axis adjusting mechanism and thus reducing the size of the laser ruler. 
   In contrast to the prior art, the laser ruler of the present invention requires less number of elements, which facilitates reducing the size of the laser ruler. In addition, by using the adjusting elements, relative positions of the optical axis adjusting mechanism along x-axis, y-axis and z-axis are adjusted. 
   The present invention has been described with reference to certain preferred and alternative embodiments which are intended to be exemplary only and not limiting to the full scope of the present invention as set forth in the appended claims.