Patent Document

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     The inventions described herein may be manufactured, used and licensed by or for the U.S. Government. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to tilt lock mechanisms. A need exists to improve locking mechanisms for optical devices based on new designs which correlate eye orientation with exterior objects. For example, virtual reality, head mounted heads up displays/visors or Night Vision Goggles (NVG) worn by airline pilots may be integrated with onboard system. Failure of the NVG to remain locked in a selected position may cause a system to fail to operate or interact with other systems which require a specific orientation, steadiness of the head mounted device or spatial relationship with exterior objects. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention may include at least one optical element and a coupling section adapted to control relative movement between the at least one optical element and the coupling section. The coupling section may include an engaging element and a detent mechanism adapted to adjustably lock the at least one optical element in a plurality of rotational positions. The rotational positions may include rotational positions around a first axis that is substantially perpendicular to a second axis of the at least one optical element, the second axis being a substantially longitudinal axis of the at least one optical element. 
     The engaging element and the detent mechanism are adapted to allow movement around the first axis when a force is applied to rotate the at least one optical element around the first axis, the force being sufficient to displace a first element of the engaging element and thus permit incremental rotational movement of the at least one optical element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       In the drawings, which are not necessarily to scale, like or corresponding parts are denoted by like or corresponding reference numerals. 
         FIG. 1  is a perspective view of a binocular night vision goggle. 
         FIG. 2  is a perspective view showing how the binocular night vision assembly is coupled to a housing. 
         FIG. 3  is a top perspective view of a housing for supporting a binocular night vision goggle. 
         FIG. 4  is a bottom perspective view of a housing for supporting a binocular night vision goggle. 
         FIG. 5  is an exploded perspective view of a housing, eccentric shaft, and o-ring. 
         FIG. 6  is a side view of a flange. 
         FIG. 7  is a side view of a plunger. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a perspective view of a binocular night vision goggle  10 . The binocular night vision goggle  10  may use a pair of monocular night vision scopes (optical elements)  12  that may be mounted and associated with one another in such a way as to provide the user of the device  10  with binocular vision. The night vision monoculars  12  may be suspended in front of a user&#39;s eyes by an elongated housing (shelf)  14 . Housing  14  may have a generally rectangular shape. Depending from the housing  14  may be a pair of spaced apart mounts  16  ( FIG. 2 ) for mounting the monoculars  12 . 
     The interpupillary distance (IPD) is defined as the distance between the user&#39;s pupils. To adjust the horizontal spacing between the monoculars  12  to match the IPD of a user, an IPD adjustment mechanism may move the monoculars  12  toward each other and away from each other. Part of the IPD mechanism may be located on the outside of housing  14  and part of it may be located between the walls of housing  14 . 
     Referring to  FIGS. 4 and 5 , the bottom of housing  14  may be divided into three sections  34 ,  36 ,  38  by four walls  18 ,  20 ,  22 , and  24 . A circular aperture may be located inside each of the walls  18 ,  20 ,  22 ,  24 . Aperture  18   a  may be located in wall  18 , aperture  20   a  may be located in wall  20 , aperture  22   a  may be located in wall  22 , and aperture  24   a  may be located in wall  24 . 
     Flanges  18   b ,  20   b ,  22   b , and  24   b  of an eccentric shaft  26  may be rotatably received in the apertures  18   a ,  20   a ,  22   a ,  24   a . Eccentric shaft  26  may be a thin elongate blade member. Inside each of the flanges  18   b ,  20   b ,  22   b ,  24   b  may be off-center apertures  18   c ,  20   c ,  22   c , and  24   c . A pivot lever  28  of the eccentric shaft  26  may be part of flange  18   b  and may extend outwardly of one end of the housing  14 . 
     Rotatably received in apertures  18   c  and  20   c  may be an IPD threaded shaft  30 . A monocular  12  ( FIGS. 1 and 2 ) may be mounted onto IPD threaded shaft  30 . One end of IPD threaded shaft  30  may extend through aperture  18   c  in flange  18   b , which may be in aperture  18   a  of wall  18 . Consequently, this end of IPD threaded shaft  30  may extend from the space in section  36  at the underside of housing  14  to the outside of wall  18 . The other end of IPD threaded shaft  30  may extend through aperture  20   c  in flange  20   b , which may be in aperture  20   a  of wall  20 . Consequently, this end of IPD threaded shaft  30  may extend from space  36  at the underside of housing  14  into the space in section  38  at the underside of housing  14 . 
     Rotatably received in apertures  22   c  and  24   c  may be an IPD threaded shaft  32 . Another monocular  12  ( FIGS. 1 and 2 ) may be mounted onto IPD threaded shaft  32 . One end of IPD threaded shaft  32  may extend through aperture  24   c  in flange  24   b , which may be in aperture  24   a  of wall  24 . Consequently, this end of IPD threaded shaft  32  may extend from the space in section  34  at the underside of housing  14  to the outside of wall  24 . The other end of IPD threaded shaft  32  may extend through aperture  22   c  in flange  22   b , which may be in aperture  22   a  of wall  22 . Consequently, this end of IPD shaft  32  may extend from space  34  at the underside of housing  14  into the space in section  38  at the underside of housing  14 . 
     The end of IPD threaded shaft  32  that may extend into space  38  from space  34  may be threaded and may carry a washer member  40  which may be secured axially on the IPD threaded shaft  32  by a threaded nut  42 . Consequently, IPD threaded shaft  32  may not move out of aperture  22   c  in flange  22   b . The end of IPD threaded shaft  30  that may extend into space  38  from space  36  may be threaded and may carry a washer member (not shown) which may be secured axially on the IPD threaded shaft  30  by a threaded nut (not shown). Consequently, IPD threaded shaft  30  may not move out of aperture  20   c  in flange  20   b.    
     The end of IPD threaded shaft  32  that may extend from space  34  to the outside of wall  24  may be attached to a control knob  44 . The end of IPD threaded shaft  30  that may extend from space  36  to the outside of wall  18  may be attached to a control knob  45 . Each of the monoculars  12  may be respectively coupled to the IPD shafts  30  and  32 . Control knobs  44  and  45  may be rotated independently of each other. When control knobs  44  and  45  are rotated, they may respectively cause IPD shafts  30  and  32  to rotate thereby moving the monoculars  12  toward and away from each other to adjust for varying eye separations. 
     As explained above, lever  28  may be part of flange  18   b . Each of the flanges  18   b ,  20   b,    22   b ,  24   b  may be connected together by the eccentric shaft  26 . Each of the flanges  18   b ,  20   b,    22   b ,  24   b  may have an off-center aperture. Off-center apertures  18   c  and  20   c  may receive IPD threaded shaft  30  and off-center apertures  22   c  and  24   c  may receive IPD threaded shaft  32 . Rotation of lever  28  may rotate eccentric shaft  26  and flanges  18   b ,  20   b ,  22   b ,  24   b , shaft  30  and shaft  32  relative to housing  14 . 
     Because the monoculars  12  may be coupled to shafts  30  and  32 , rotation of lever  28  may tilt each of the monoculars  12  relative to housing  14  and relative to a user&#39;s eyes. Thus, the eccentric shaft  26  and its associated flanges provide a means of tilting the line-of-sight (longitudinal axis) of the two monoculars  12  simultaneously. The lever  28  may be used to adjust the tilt of the monoculars  12  to align with the user&#39;s line-of-sight. That is, the lever  28  may be used to rotate the monoculars  12  about an axis that is substantially perpendicular to the longitudinal axis through the monoculars  12 . 
     As shown in  FIG. 5 , the eccentric shaft  26  may use an o-ring  46  to provide rotational friction between the eccentric shaft  26  and the housing  14 . The o-ring  46  may be placed in a groove  18   d  of flange  18   b , near adjustment lever  28 . After the eccentric shaft  26  is assembled to the housing assembly, the o-ring  46  may provide frictional resistance against the housing  14 . The rotational friction force may occur between o-ring  46  and aperture  18   a  of wall  18  when flange  18   b  is inserted into aperture  18   a . Thus, the o-ring  46  may act as a frictional resistor between the eccentric shaft  26  and the housing  14 . 
     The frictional interface between o-ring  46  and aperture  18   a  may be controlled by tight tolerances between flange  18   b  of the eccentric shaft  26 , the housing  14 , and the o-ring  46 . The o-ring  46  may provide some rotational friction for shaft  26 . Further rotational friction and a tilt adjustment lock may be provided by a plunger and detent mechanism. 
       FIG. 6  is an enlarged, side view of flange  22   b  shown in  FIG. 5 . Flange  22   b  may include a plurality of detents  48  formed on its circumference. Detents  48  may be in the form of, for example, dimples, grooves, etc. As shown in  FIG. 6 , detents  48  may comprise substantially V-shaped grooves that extend transversely across the width of the flange  22   b . The sides of the V-shaped grooves may form about a 45 degree angle. Each detent  48  may correspond to a locked position of the device  10 . The number of detents  48  may vary depending on the number of locked positions desired. The circumferential extent and spacing of the detents  48  may vary depending on the range and precision of tilt adjustment desired. In one embodiment, six detents  48  are circumferentially spaced about 10 degrees apart to produce six locked settings over a sixty degree range of tilt. 
       FIG. 7  is an exemplary enlarged, side view of a plunger  50  shown in  FIGS. 3-5 . Plunger  50  may include a first element comprising a tip  52  for engaging the detents  48 . Tip  52  may be spherical. Tip  52  is outwardly biased by an internal spring (not shown) in plunger  50 . Plunger  50  may include threads  54  for threading into housing  14 . The thickness of housing  14  in the vicinity of plunger  50  may be increased by mounting an exterior plate  56  ( FIGS. 3-5 ) to housing  14  using, for example, fasteners  58 , plastic welding, adhesives, etc. Plunger  50  may be mounted to housing  14  such that the tip  52  abuts a detent  48  in flange  22   b . As shown in  FIG. 5 , the tip  52  may be located at wall  22 . 
     As lever  28  ( FIGS. 4 and 5 ) is rotated, shaft  26  with flange  22   b  rotates. As flange  22   b  rotates, the tip  52  of plunger  50  moves in and out of the detents  48  due to the spring in the plunger  50 . When the desired tilt position is reached, the tip  52  seats in the chosen detent  48  and locks the device  10  in position. The force required to rotate lever  28  to change tilt positions may be altered by, for example, changing the spring force in the plunger  50 . In one embodiment, the plunger  50  is a 4 millimeter diameter plunger with a spring force in the range of about 2.5 Newtons minimum (uncompressed) to about 12.5 Newtons maximum (fully compressed). Of course, other spring forces may be used. The spring force may be small enough to allow one-handed adjustment by the user, yet large enough to prevent movement of the optical elements caused by, for example, vibration. 
     Another way to adjust the spring force is to move the entire plunger  50  toward or away from the detents  48 . If the plunger  50  is threaded into the housing  14 , the plunger may be adjusted by threading it into or out of the housing  14 . Of course, the tip and internal spring must have sufficient travel to bear against the detents  48  and also be retracted into the plunger  50  as the shaft  26  rotates. 
     The tilt adjustment and lock mechanism has been described with reference to a night vision goggle. However, the inventive mechanism may be incorporated into a variety of optical devices and may be used for adjustments other than tilt. 
     While the invention has been described with reference to certain preferred embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof.

Technology Category: f