Patent Publication Number: US-7222432-B2

Title: Method of assembling reticle module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the priority benefit of Taiwan application serial no. 93124511, filed Aug. 16, 2004. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method of assembling an alignment module. More particularly, the present invention relates to a method of assembling a reticle module. 
   2. Description of the Related Art 
   A conventional finder module uses a single reticle to align with a target. However, the alignment accuracy of a single reticle finder is quite limited to achieve a higher level of alignment. For example, the finder of a rifle is normally disposed on a plane surface perpendicular to the gun barrel. In other words, the axis of the reticle module is in parallel to the gun barrel. Since the finder and the target may not lie on mutually parallel planes, there is no guarantee that the shooter can hit the target. Moreover, the amount of errors involved may not be perceptible to the human eye. 
   To increase the accuracy of aiming, a finder having two reticles has been developed. When the plane surface of the finder rests and the plane surface of the target form an angle, the user can easily spot this through the finder because the reticles inside the finder will not overlap. Hence, any spatial misalignment between the target and the finder can be easily recognized through the human eye. 
   When a finder with dual reticle elements aligns with a target, the reticles must overlap each other completely. Therefore, in the process of assembling this type of finder, the degree of alignment between the two reticles is very important. 
   SUMMARY OF THE INVENTION 
   Accordingly, at least one objective of the present invention is to provide a method of assembling a reticle module having higher alignment accuracy. 
   To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a method of assembling a dual reticle module. The dual reticle module mainly comprises a first element and a second element. The first element has a first reticle and the second element has a second reticle. The method of assembling the dual reticle module includes providing a screen and a collimated light beam and setting the screen along the path of the collimated light beam. Thereafter, the first element and the second element are disposed between the screen and the collimated light beam. The first reticle and the second reticle are set in a direction perpendicular to the collimated light beam so that the first reticle of the first element and the second reticle of the second element are projected on the screen. The position of the first element and the second element are adjusted until the projected image of the first reticle and the second reticle coincides with each other on the screen. Finally, the relative position between the first element and the second element is fixed. 
   According to one embodiment of the present invention, the screen has a calibration chart. In addition, the process of adjusting the position of the first element and the second element further comprises overlapping the projected image of the first reticle and the second reticle with the calibration chart on the screen. 
   The present invention also provides a method of assembling a dual reticle module. The dual reticle module mainly comprises a first element and a second element. The first element has a first reticle and the second element has a second reticle. The method of assembling the dual reticle module includes providing a screen and a collimated light beam and setting the screen along the path of the collimated light beam such that the collimated light beam impinges the screen perpendicularly. Furthermore, the screen has a calibration chart thereon. Thereafter, the first element is disposed between the screen and the collimated light beam so that the first reticle is perpendicular to the collimated light beam. The position of the first element is adjusted until the first reticle overlaps with the calibration chart on the screen. After that, the second element is disposed between the screen and the collimated light beam so that the second reticle is perpendicular to the collimated light beam. Similarly, the position of the second element is adjusted until the second reticle overlaps with the calibration chart on the screen. Finally, the relative position between the first element and the second element is fixed. 
   According to one embodiment of the present invention, the collimated light beam is provided by a projector or a collimator. 
   According to one embodiment of the present invention, the method of fixing the relative position between the first element and the second element includes fastening the two together. In one embodiment, the first element and the second element are fastened together using screws, adhesive glue, pressure latches or rivets. 
   The present invention also provides a method of assembling a reticle module. The reticle module comprises a plurality of elements with each element having a reticle. The method of assembling the reticle module includes providing a screen and a collimated light beam and setting the screen along the path of the collimated light beam. Thereafter, the elements are disposed between the screen and the collimated light beam such that projected images of the reticles is formed on the screen. The reticles of the elements are set in a direction perpendicular to the collimated light beam. The positions of these elements are adjusted until the projected images of the reticles overlap on the screen. Finally, the relative positions between various elements are fixed. 
   According to the embodiment of the present invention, the screen may have a calibrating chart thereon. Furthermore, the step of adjusting the elements may further include adjusting the positions of the elements so that the projected images of the reticles overlap with the calibrating chart on the screen. 
   The present invention also provides a method of assembling a reticle module. The reticle module comprises a plurality of elements with each element having a reticle. The method of assembling the reticle module includes providing a screen and a collimated light beam and setting the screen along the path of the collimated light beam such that the collimated light beam impinges the screen perpendicularly. Furthermore, the screen has a calibration chart thereon. Thereafter, each element is sequentially disposed between the screen and the collimated light beam. The reticle of each element is set in a direction perpendicular to the collimated light beam. The position of each element is sequentially adjusted so that the reticle of each element overlaps with the calibrating chart on the screen. Finally, the relative positions of between these elements are fixed. 
   According to the embodiment of the present invention, the collimated light beam is provided by a projector or a collimator. 
   According to one embodiment of the present invention, the method of fixing the relative positions between the elements includes fastening the elements together. In one embodiment, the elements are fastened together using screws, adhesive glue, pressure latches or rivets. 
   The present invention utilizes a collimated light beam to project an image of two or more reticles onto a screen and then adjusts the projected images of the reticles so that the reticles overlap in a direction of extension of the collimated light beam. Ultimately, a reticle module with precise alignment is assembled. 
   It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       FIGS. 1A through 1C  are perspective views showing the method of assembling a dual reticle module according to one preferred embodiment of the present invention. 
       FIG. 2  is a perspective view of a dual reticle module according to another preferred embodiment of the present invention. 
       FIGS. 3A and 3B  are perspective views showing some of the steps for assembling a dual reticle module according to another preferred embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
   The process of assembling a reticle module in the present invention utilizes a collimated light beam to ensure a precise overlapping of the reticles. In the following, embodiments are used to explain the method. It should be noted that a dual reticle module is used to illustrate the concept of the present invention. However, the method of the present invention is not limited to the fabrication of a dual reticle module but can be applied to other module having three or more reticles therein. 
     FIGS. 1A through 1C  are perspective views showing the method of assembling a dual reticle module according to one preferred embodiment of the present invention. As shown in  FIG. 1A , a screen  100  and a collimated light beam  102  are provided. The screen  100  is positioned along the path of the collimated light beam  102  such that the collimated light beam  102  impinges the screen  100  perpendicularly. In the embodiment of the present invention, a projector or a collimator provides the collimated light beam  102 . 
   As shown in  FIG. 1B , a first element  110  with a first reticle  112  and a second element  120  with a second reticle  122  are positioned between the collimated light beam  102  and the screen  100 . The first reticle  112  and the second reticle  122  are set in a direction perpendicular to the collimated light beam  102 . In other words, the direction of travel of the collimated light beam  102  is parallel to the axes  130  of the first element  110  and the second element  120  so that a projected image of the first reticle  112  and the second reticle  122  are formed on the screen  100 . The first reticle  112  on the first element  110  and the second reticle  122  on the second element  120  are located in the same relative position. In fact, the first element  110  and the second element  120  are frames for holding the first reticle  112  and the second reticle  122 . Thereafter, the relative position between the first element  110  and the second element  120  are adjusted so that the projected image of the first reticle  112  on the screen  100  overlaps with the projected image of the second reticle  122  on the screen  100 . 
   As shown in  FIG. 1C , the relative position between the first element  110  and the second element  120  is fixed to ensure the first reticle  112  and the second reticle  122  in the axial direction  130  of the first element  110  and the second element  120  coincide. Hence, the process of assembling the dual reticle module  108  is complete. The method of fixing the relative position between the first element  110  and the second element  120  includes fastening the first element  110  and the second element  120  together. For example, the first element  110  and the second element  120  can be fastened together using screws, adhesive glue, pressure latches, rivets or other means. In addition, the first element  110  and the second element  120  may be separately fastened to a carrier  106  (as shown in  FIG. 2 ). The carrier  106  is, for example, a fixture capable of fastening the first element  110  and the second element  120  at a fixed separation. Thus, there is no fixed design in the present invention to set the first element and the second element at a fixed relative position. Anyone familiar with mounting elements together may select a method appropriate to a particular situation and still be considered as within the scope of the present invention. 
   In another embodiment of the present invention, a calibrating chart  104  is also disposed on the screen  100 . In the process of assembling a dual reticle module, the collimated light beam  102  is set to impinge the screen  100  perpendicularly. Thereafter, a first element  110  is disposed between the screen  100  and the collimated light beam  102  so that a projected image of the first reticle  112  appears on the screen  100 . The position of the first element  110  is adjusted until the projected image of the first reticle  112  on the screen overlaps with the calibrating chart  104  as shown in  FIG. 3A . 
   As shown in  FIG. 3B , the second element  120  is disposed between the screen  100  and the collimated light beam  102  so that a projected image of the second reticle  122  appears on the screen  100 . The second element  120  may be disposed between the screen  100  and the first element  100  or disposed between the first element  110  and the collimated light beam  102 . In the present invention, there is no particular constraint on the positioning of the first element  110  and the second element  120  between the screen  100  and the collimated light beam  102 . Thereafter, the second element is adjusted so that the projected image of the second reticle  122  overlaps with the calibrating chart  104  on the screen  100 . In other words, the projected image of the first reticle  112  and the projected image of the second reticle  122  coincide on the screen  100 . Finally, as shown in  FIG. 1C , the relative position between the first element  112  and the second element  122  is fixed to complete the process of assembling a dual reticle module. 
   It should be noted that the present embodiment also permits the simultaneous disposition of the first element  110  and the second element  120  between the screen  100  and the collimated light beam  102 . Thereafter, the first element  110  and the second element  120  are simultaneously adjusted so that the projected image of the first reticle  112  and the second reticle  122  overlap with the calibrating chart  104  on the screen  100 . In other words, the present invention has no particular constraint on the order of adjustment between the first element  110  and the second element  120 . 
   In summary, the present invention utilizes a collimated light beam to produce a projected image of a first reticle and a second reticle on a screen. By adjusting the projected image of the first reticle and the second reticle, the first reticle and the second reticle in the axial direction of the first element and the second element are made to coincide. It should be noted that a set of lenses could be used to magnify the projected image of the first reticle and the second reticle on the screen. Hence, the projected image of the first reticle and the second reticle on the screen can be used to micro-adjust the relative position between the first reticle and the second reticle and increase their overlapping precision. 
   It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.