Abstract:
A disc-based altitude-azimuth telescope mount for mounting and adjusting a telescope along altitude and azimuth axes. The telescope mount includes an azimuth disc assembly for facilitating adjustment of the telescope along the azimuth axis and an altitude disc assembly for facilitating adjustment of the telescope along the altitude axis. A friction adjusting mechanism operably engages the azimuth disc assembly and the altitude disc assembly to prevent inadvertent movement of the telescope along both axes. A digital setting circle may be operably connected to the disc assemblies to facilitate automatic adjustment of the telescope, as desired.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Patent Application No. 60/445,991, filed Feb. 6, 2003, and U.S. Non-Provisional patent application Ser. No. 10/772,986, filed Feb. 5, 2004, both of which are incorporated by reference herein in their entireties. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to telescope mounts, and more particularly, to a disc-based alt-azimuth mount for telescopes. 
   2. Description of the Prior Art 
   A wide variety of telescope mounts are available for both astronomical and non-astronomical telescopes. These generally fall under two broad categories, namely equatorial and altitude-azimuth mounts. Equatorial mounts are designed to follow the celestial sphere by moving the telescope in one axis only. An alt-azimuth mount, on the other hand, is designed to move in two axes to follow both the celestial sphere and the vertical altitude dimension. 
   Because of its simplicity, the alt-azimuth mount has gained popularity in recent years as a multi-purpose astronomical and non-astronomical mount. The new professional telescopes are now being built with alt-azimuth mounts and computer driven motors moving in both axes to track celestial objects. The mount has also gained popularity with the advent of new precision-built and optically-correct wide field refractor (lens in front) telescopes being used for astronomical and terrestrial objects. 
   Unfortunately, existing alt-azimuth telescope mounts have proven to be quite amendable to vibrations and do not remain rigid to outside forces such as wind or touch. Such vibrations are most evident in single arm mounts and intensify as the length of the arms is increased. Although adding a second arm has reduced this problem somewhat, it has lead to a host of other design deficiencies, such as not being able to carry telescopes of varying widths. One notable drawback found in existing alt-azimuth telescope mounts is that they are not able to handle telescopes of varying sizes without the addition of counter-balance devices and do not permit the mount to swing freely without interference from the telescope hitting the base of the mount. 
   A further problem encountered with existing alt-azimuth telescope mounts is that they are not able to handle various size loads such as cameras, eyepieces and the like without unwanted movement caused by imbalance. Many telescopes allow the observer to interchange eyepieces, allowing an increase or decrease in magnification. Cameras may also be used in place of eyepieces in order to take pictures. Modern eyepieces weight can range from as little as two ounces for high magnification, to over two and a half pounds for a wide field low magnification. If the telescope is balanced for a heavy eyepiece and the eyepiece is removed, the telescope will rotate forward. Likewise, if the telescope is balanced for a light weight (or no eyepiece), then the telescope will drop in the rear. To overcome this problem, some mounts have locks to prevent the axis from moving. The observer moves the telescope to the object and locks the axis. However, the object seldom remains stationary (a sighted dear runs or the earth rotates, for example). In order to address this problem, designers have added slow motion mechanisms. These mechanisms, however, have generally proven cumbersome and inadequate in practice because the mount axis must be locked during use. Similarly, friction locks have not adequately addressed this issue. 
   Additionally, existing mounts often do not maintain all axes and planes perfectly orthogonal with each other as required for accuracy when electronic shaft encoders are utilized with computerized locaters, commonly known in the art as setting circles. Significant errors are introduced where the axes of the telescope mount are not perfectly orthogonal. 
   Accordingly, there is an established need for a disc based alt-azimuth telescope mount for use with any of a variety of existing telescopes that addresses and overcomes the aforementioned problems and disadvantages found in existing telescope mounting systems. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a disc based alt-azimuth telescope mount for use with any of a variety of existing telescopes. 
   An object of the present invention is to provide a disc based alt-azimuth telescope mount that permits the magnitude of friction to be easily adjusted between discs. 
   A further object of the present invention is to provide a disc based alt-azimuth telescope mount wherein ball bearings rather than the disc surface are utilized to permit a disc-tightening nut to turn with the shaft of the telescope mount. 
   It is also an object of the present invention to provide a disc-based alt-aximuth telescope mount that does not require constant friction adjustment. 
   Another object of the present invention is to provide a disc based alt-azimuth telescope mount that eliminates the need to utilize set screws, pins, and other mechanisms that permit friction adjusting nut loosening over time. 
   An additional object of the present invention is to provide a disc based alt-azimuth telescope mount that is configured to accept any of a wide variety of loads such as eyepieces, cameras, and the like, without rebalance. 
   Yet another object of the present invention is to provide a disc based alt-azimuth telescope mount wherein the axes are orthogonal such that the shafts within each axis are positioned at right angles. 
   A further object of the present invention is to provide a disc based alt-azimuth telescope mount configured to permit electronic shaft encoders to be mounted directly to the axis shafts. 
   Another object of the present invention is to provide a disc based alt-azimuth telescope mount optionally fitted with electronic shaft encoders which, when used, are located on the same plane of the corresponding azimuth or altitude axis so that battery-powered astronomical setting circles and other equipment can be utilized without cables interfering with the telescope mount operation. 
   An additional object of the present invention is to provide a disc based alt-azimuth telescope mount that is compact in size and easy to store and transport. 
   Yet another object of the present invention is to provide a disc based alt-azimuth telescope mount wherein the telescope is mounted to the side and hangs over the side of the mount such that it is capable of aiming through a wide range from below the horizon to overhead. 
   A further object of the present invention is to provide a disc based alt-azimuth telescope mount wherein rigidity due to the close coupling (short arms) is inherent to the design. 
   Another object of the present invention is to provide a disc based alt-azimuth telescope mount designed for use with both astronomical and terrestrial telescopes and lenses. 
   An additional object of the present invention is to provide a disc based alt-azimuth telescope mount that does not require locks during the use of slow motion controls. 
   These and other objects, features, and advantages of the present invention will become more readily apparent from the attached drawings and the detailed description of the preferred embodiments, which follow. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of the invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the invention, where like designations denote like elements, and in which: 
       FIG. 1  is a front view of the disc based alt-azimuth telescope mount shown with a telescope in place in accordance with a preferred embodiment of the present invention; 
       FIG. 2  is a rear, perspective view of the telescope mount provided on a telescope tripod; 
       FIG. 3  is a front view of the disc based alt-azimuth telescope mount shown with a telescope in place in accordance with a preferred embodiment of the present invention, with the front, rear, side and top support plates of a mount housing removed from the telescope mount for clarity; 
       FIG. 4  is a top, partial cross-sectional view of the disc based alt-azimuth telescope mount in accordance with a preferred embodiment of the present invention showing optional electronic shaft encoders and digital setting circles, with a top support plate of the mount housing removed from the mount; 
       FIG. 5  is a front cross-sectional view of the disc-based alt-azimuth telescope mount showing optional electronic shaft encoders and digital setting circles in accordance with a preferred embodiment of the present invention, with the front support plate of the mount housing removed for clarity; 
       FIG. 6  is a partial front view of the disc based alt-azimuth telescope mount utilized with a typical slow motion control mechanism in accordance with a preferred embodiment of the present invention; 
       FIG. 7  is a front, perspective view of the disc based alt-azimuth telescope mount of the present invention, with the mount housing removed from the mount, more particularly illustrating rotation of an azimuth axis rotating disc to facilitate adjustment of a telescope along an azimuth axis and rotation of an altitude axis rotating disc to facilitate adjustment of the telescope along an altitude axis; 
       FIG. 8  is a side view of the disc-based alt-azimuth telescope mount, with the side support plate of the mount housing removed to illustrate an altitude axis fixed disc of the mount; 
       FIG. 9  is a cross-section taken along section lines  9 - 9  in  FIG. 8 , illustrating a ball bearing mechanism for each friction adjusting nut, which allows the adjusting mechanism to turn freely with the shaft and having no contact with the disc wall; 
       FIG. 10  is a side view of a prior art equatorial telescope mount; 
       FIG. 11  is a side view of a prior art alt-azimuth telescope mount; 
       FIG. 12  is a front view of a prior art two arm alt-azimuth telescope mount; and 
       FIG. 13  is a side view showing the center of gravity on a typical prior art telescope mount; and 
       FIG. 14  is an exploded view illustrating slidable engagement of a side support plate with a front support plate and a rear support plate of the mount housing. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Shown throughout the figures, the present invention is generally directed towards a disc based alt-azimuth telescope mount for use with any of a variety of existing telescopes. 
   Referring initially to  FIG. 10 , a prior art equatorial telescope mount  70 , provided on a tripod  75 , is shown. As shown in the Figure, the telescope mount  70  of the prior art includes a lower or right ascension axis  71  disposed at an angle to the observer&#39;s latitude  72  and pointed north (northern hemisphere) or south (southern hemisphere). This places the telescope  73  at the same plane as the earth, which allows the telescope  73  to follow a curve equal to the celestial curve at the observer&#39;s location, making it possible for the telescope  73  to track celestial objects as the earth spins with a single movement of the right ascension axis  71  (east-west movement) while the declination axis  74  (north-south movement) remains stationary while the object is being observed. 
   A prior art altitude-azimuth (also called alt-azimuth or azimuth) telescope mount  78  is shown in  FIGS. 11 and 12 . This type of telescope mount typically must be adjusted in two distinct movements. A horizontal movement relative to the observer&#39;s position (azimuth) is accomplished by adjusting the telescope  79  along an azimuth axis  80 . Vertical adjustment (altitude) of the telescope  79  is accomplished by adjusting the telescope  79  along an altitude axis  81 . It will be appreciated by those skilled in the art that the alt-azimuth telescope mount  78  must be moved along both axes  80 ,  81  to track the celestial sphere. Typical prior art alt-azimuth telescope mounts  78  can be mounted on a standard camera tripod  82 . Such telescope mounts are either constructed with one or two arms  83  with each arm  83  mounted at a right angle to the azimuth axis  80 . Alt-azimuth telescope mounts  78  utilize straight vertical and horizontal movements for adjustment, rather than following a curve, such as is required on equatorial-type mounts. 
     FIG. 13  shows a center of gravity on a typical prior art telescope mount  86 . As shown, the telescope  87  is balanced in a saddle near the center of gravity  88  generally at the center of the altitude axis of the telescope mount  86 . 
   Referring to  FIGS. 1-8 , the disc based alt-azimuth telescope mount, hereinafter referred to as the telescope mount, of the present invention is generally indicated by reference numeral  1 . The telescope mount  1  can be used with any of a wide variety of known support structures such as, for example, a standard or conventional telescope tripod  2 . The tripod  2  typically includes multiple tripod legs  3  which extend downwardly from a mount base  4 . 
   Briefly, and as hereinafter further described, the telescope mount  1  includes an azimuth disc assembly  8 , which is mounted on the tripod  2 ; a mount housing  23 , which is mounted on the azimuth disc assembly  8 ; and an altitude disc assembly  13 , which is mounted on the mount housing  23 . As illustrated in  FIGS. 1 and 2 , a telescope mount bracket  36  is mounted on the altitude disc assembly  13 . A conventional telescope  37  is typically removably mounted on the telescope bracket  36 . Accordingly, as illustrated in  FIG. 1 , the azimuth disc assembly  8  is used to adjust the telescope  37  along an azimuth axis  40  (i.e., right or left), whereas the altitude disc assembly  13  is used to adjust the telescope  37  along an altitude axis  41  (i.e., up or down), in order to properly position the telescope  37  for sighting a celestial or non-celestial object. Likewise, once the object has been sighted, the azimuth disc assembly  8  and the altitude disc assembly  13  are used to prevent inadvertent movement of the telescope  37  along the azimuth axis  40  and the altitude axis  41 , respectively. 
   As shown in  FIG. 5 , the azimuth disc assembly  8  includes an azimuth axis rotating disc  10  which is mounted on a shaft  14 , typically through a mechanical press-fit. A mount-securing knob  5 , from which extends a mount screw  6 , threadibly engages the shaft  14  to further secure the telescope mount  1  to the tripod  2 . Accordingly, the azimuth axis rotating disc  10  is capable of rotating on the shaft  14 , as hereinafter further described. An azimuth axis fixed disc  9  is further mounted on the shaft  14 , typically on a shaft bearing  15 , such that the shaft  14  passes freely through the bearing  15  and through a central opening (not shown) in the azimuth axis fixed disc  9 . A friction disc spacer  11 , which may be plastic, is interposed between the azimuth axis rotating disc  10  and the azimuth axis fixed disc  9 . Accordingly, while the azimuth axis rotating disc  10  will turn on the shaft  14 , the azimuth axis fixed disc  9  will turn with the rotating disc  10  only if there is enough friction between the two. A friction adjusting nut  17  threadibly engages the shaft  14  and impinges against an adjusting nut bearing  16  recessed in the upper face of the rotating disc  10 . By threading the friction adjusting nut  17  against the adjusting nut bearing  16 , the discs  9 ,  10  can be squeezed together against the friction disc spacer  11  to vary the amount of friction between the discs  9 ,  10 . It will be appreciated by those skilled in the art that the amount of friction can also vary depending upon the diameter of the discs  9 ,  10  and spacer  11  of the azimuth disc assembly, as well as the type of material used for the friction disc spacer  11 . 
   As illustrated in  FIGS. 1 ,  2 , and  5 , the telescope mount  1  typically further includes the mount housing  23 . The mount housing  23  includes a front support plate  24  and a rear support plate  27 , each of which extends upwardly from the upper surface of the azimuth axis rotating disc  10 . As illustrated in  FIG. 5 , disc mount bolts  18  may be used to mount the front support plate  24  and the rear support plate  27  to the azimuth axis rotating disc  10 . 
   A side support plate  25  typically slidably and removably engages the front support plate  24  and the rear support plate  27 , as illustrated in  FIG. 14 . A top support plate  26  typically removably engages the front support plate  24  and the rear support plate  27 . Accordingly, the side support plate  25  may be provided with flanges (not shown) which slidably interlock with companion grooves (not shown) provided in the front support plate  24  and the rear support plate  27 . Likewise, the top support plate  26  may be provided with flanges (not shown) which slidably interlock with companion grooves (not shown) provided in the front support plate  24  and the rear support plate  27 . Alternatively, screws (not shown) can be utilized and put on with screws instead of being slid on. 
   As further illustrated in  FIG. 5 , the altitude disc assembly  13  includes an altitude axis fixed disc  20  which is mounted to the front support plate  24  and the rear support plate  27 , typically using disc mount bolts  18 . A shaft  14  extends freely through an adjusting nut bearing  16 , which is recessed in the altitude axis fixed disc  20 , and a shaft bearing  15 , which is provided in the center of the altitude axis fixed disc  20 . An altitude axis rotating disc  19  is mounted on the shaft  14 , typically through a mechanical press-fit. Accordingly, the altitude axis rotating disc  19  rotates with the shaft  14 , whereas the shaft  14  rotates freely with respect to the altitude axis fixed disc  20 . A friction disc spacer  21 , which may be plastic, for example, typically has the same diameter as that of the discs  19 ,  20  and is interposed between the discs  19 ,  20 . A friction adjusting mechanism  17 , such as a nut or knob, for example, threadibly engages the shaft  14  and can be rotated against the adjusting nut bearing  16  to press the discs  19 ,  20  against the friction disc spacer  21  and increase the friction between the discs  19 ,  20 , as hereinafter described. 
   As illustrated in  FIG. 9 , the adjusting nut bearing  16  of the altitude axis fixed disc  20  preferably includes an annular ball bearing cavity  32  having multiple ball bearings  33 . Accordingly, it will be appreciated that the adjusting nut bearing  16  allows the friction adjusting nut  17  to turn freely with shaft  14  so that the friction adjusting nut  17  does not inadvertently loosen during adjustment. In a most preferred embodiment, the azimuth axis rotating disc  10  will be similarly configured. In order to vary the amount of frictional support, the friction adjusting nut  17  can be loosened or tightened as desired using a standard tool, such as a wrench, as described in more detail below. 
   As illustrated in  FIG. 8 , a wrench access space  31  is typically defined between the azimuth axis rotating disc  10  and the altitude axis fixed disc  20 . Accordingly, a tool, such as a wrench (not shown), can be inserted through the wrench access space  31  to loosen or tighten the friction adjusting nut  17  on the azimuth disc assembly  8 . Furthermore, side support plate  25 , the top support plate  26 , or both the side support plate  25  and the top support plate  26  can be removed from the mount housing  23 , as illustrated in  FIG. 8 , to provide access to the friction adjusting nut  17  of the azimuth disc assembly  8  and/or the altitude disc assembly  13 . 
   As illustrated in  FIGS. 4 and 5 , optional digital setting circles  28 , which may be conventional, can be provided on the mount housing  23 , in which case electronic shaft encoders  30  are provided on the shaft  14  of the azimuth disc assembly  8 , as well as the shaft  14  of the altitude disc assembly  13 . Cables  29  connect the digital setting circles  28  to the respective electronic shaft encoders  30 . Accordingly, digital setting circles  28  may be used to indicate the position of the azimuth axis rotating disc  10  so that the telescope  37  can be moved along the azimuth axis. Likewise, digital setting circles  28  may be used to indicate the position of the altitude axis rotating disc  19  so that the telescope  37  can be moved along the altitude axis  41 , during operation of the telescope mount  1  as hereinafter further described. 
   Referring next to  FIGS. 1 ,  3  and  7 , in typical operation of the telescope mount  1 , a conventional telescope  37 , typically having an eyepiece holder  38  and a focusing knob or knobs  39 , is attached to the telescope mount bracket  36  ( FIG. 2 ) of the telescope mount  1 . The position of the telescope  37  is adjusted along the azimuth axis  40  (i.e., right or left) and along the altitude axis  41  (i.e., up or down), typically in conjunction with the operation of the digital setting circles  28 . Accordingly, coordinate information which corresponds to the location of an object to be sighted through the telescope  37  is initially programmed into the digital setting circles  28 . Next, using position information obtained from the digital setting circles  28 , through the electronic shaft encoders  30 , the shaft  14  of the azimuth disc assembly  8  and the shaft  14  of the altitude disc assembly  13  are turned, as desired, to position of the telescope  37  appropriately along both axes. 
   As illustrated in  FIG. 7 , the digital setting circles  28  indicate the position of the azimuth axis rotating disc  10  along a rotational axis  10   a . Once the position of the azimuth axis rotating disc  10  is known, the mount housing  23 , altitude axis disc assembly  13 , and attached telescope  37  are positioned along the azimuth axis  40  until the position of the telescope  37  corresponds to the azimuth position of the object to be sighted. 
   As further illustrated in  FIG. 7 , the digital setting circles  28  also indicate the position of the altitude axis rotating disc  19  along a rotational axis  19   a . Once the position of the altitude axis rotating disc  19  is known, the attached telescope  37  can be adjusted along the altitude axis  41  until the sighting position of the telescope  37  corresponds to the altitude position of the object to be sighted. Accordingly, the telescope  37  is positioned at both the azimuth position and the altitude position programmed into the digital setting circles  28 , so that the object can be sighted through the eyepiece (not shown) of the telescope  37 . 
   It will be appreciated by those skilled in the art that the azimuth disc assembly  8  and the altitude disc assembly  13  must be frictionally adjusted so as to prevent inadvertent drifting or movement of the telescope  37  from a sighted position during use. This adjustment is typically only required during the initial setting up of a new telescope on the mount or substantial changes in auxiliary equipment, such as, for example, during changing of a heavy eyepiece for a lighter eyepiece. This is accomplished by using a tool, such as a wrench (not shown), to tighten the friction adjusting nuts  17  against the adjusting nut bearings  16  of the respective azimuth disc assembly  8  and altitude disc assembly  13 . Accordingly, as best illustrated in  FIGS. 3 and 7 , upon tightening of the nut  17  of the azimuth disc assembly  8 , the azimuth axis fixed disc  9  and the altitude axis rotating disc  10  are pressed against the intervening friction disc spacer  11 . This prevents the azimuth axis rotating disc  10  from rotating with respect to the azimuth axis fixed disc  9  and inadvertently moving the telescope  37  from the sighted position along the azimuth axis  40 . Similarly, upon tightening of the nut  17  of the altitude disc assembly  13 , the altitude axis fixed disc  20  and the altitude axis rotating disc  19  are pressed against the intervening friction disc spacer  21 . This prevents the altitude axis rotating disc  19  from rotating with respect to the altitude axis fixed disc  20  and inadvertently moving the telescope  37  from the sighted position along the altitude axis  41 . It should be noted that the frictional adjustment described need only be performed at the initial set up of the telescope mount  1  and will generally not be required again unless substantial changes in weight distribution are initiated, such as, for example, during the changing of a lighter eyepiece for a much heavier one or the replacement of one telescope for another of substantially differing weight. Frictional adjustment is not anticipated, however, for typical eyepiece changes, and it is seen that the telescope mount  1  is always in a sight-ready mode and available for immediate use as desired. 
   After a period of time has elapsed since initial sighting of the celestial object through the telescope  37 , it frequently becomes necessary to re-adjust the position of the telescope  37  along the azimuth axis  40  to compensate for the rotation of the earth. Accordingly, it is seen that the telescope can be manually moved by the observer by overcoming the friction between the disc  19  and the friction disc spacer  21  by applying sufficient force to permit the telescope  37  to move freely. Upon coming to rest, however, the friction between the disc  19  and the friction disc spacer  21  will preferably be sufficient to maintain the current position in a secure manner until movement to a new position is desired. 
   In the present invention, the disc based alt-azimuth telescope mount  1  is configured with the altitude axis disc assembly  13  mounted to the side of the azimuth axis disc assembly  9 . The telescope  37  can be mounted in the center of gravity of the altitude axis  41 . As such, no counter balance will be required and the telescope  37  will not hit the azimuth axis  40 . Because no counter balance is needed, the shafts  14  can be kept short and smaller in diameter. This will allow the shafts  14  to terminate on the same plane. The electronic shaft encoders  30  may be mounted directly to the ends of the shafts  14 . This is a major advantage because battery-powered digital setting circles  28  may be mounted without external cables  29  passing through the shafts  14  or wrapping around the mount  1  as it is turned on its axis. 
   In a most preferred embodiment, the disc based telescope mount will include a shaft threaded on one end such that a nut can be used to allow the disc to be pulled together. This permits the tension or friction between the disc to be easily adjustable. In the disc based telescope mount of the present invention, a ball bearing assembly will be added between the nut and the disc. This permits the nut to turn freely with the shaft and still be easily adjustable. 
   As shown in  FIG. 6 , the plastic friction disc spacer  21  may be formed with a tab  50  added to it so that the tab  50  protrudes past the altitude axis rotating disc  19 . Further, a slow motion threaded rod or screw  46  with a knob  44  (or alternatively, a motor) and slow motion threaded block  45  can be secured to the altitude axis rotating disc  19  in such a manner to allow the screw  46  to push on the tab  50 . A spring  48  and spring block assembly  49  pushing in the opposite direction will keep tension on the tab  50 . As the knob  44  is turned, disc  19  will move with friction disc spacer  21 , which in turn will move the telescope  37  along the altitude axis  41 . Since friction will always exist between the disc, no locks will be needed. If however, the telescope (axis) is manually moved by the observer, the friction between the disc  19  and the friction disc spacer  21  will be overcome and the telescope  37  will move freely. A similar slow motion control mechanism can be added to the azimuth disc assembly  8  to provide slow motion control of the telescope  37  along the azimuth axis  40 , as well. 
   Since many modifications, variations, and changes in detail can be made to the described preferred embodiments of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Thus, the scope of the invention should be determined by the appended claims and their legal equivalence.