Abstract:
The present invention provides a stable tripod stand for sensitive optical devices such as telescopes and the like. The tripod may be moved around on wheels which are coupled to casters and when positioned may be secured to the ground to provide an adjustable and highly stable support that significantly reduces the incidence of jitter. The tripod includes a stabilizer member that extends through the casters to selectively engage the ground. The leg members of the tripod have a triangular shape and support links between the platform and the leg members form interlocking triangular supports which reinforce the leg members.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable.  
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX  
       [0003]     Not applicable.  
       BACKGROUND OF THE INVENTION  
       [0004]     The following invention relates to a tripod stand and more particularly to a tripod stand for supporting a device above a horizontal surface such as the ground.  
         [0005]     Precision instruments, such as cameras and telescopes, require stable support structures that are moveable and provide a degree of adjustability, yet which can provide stability free of jitter. In the past, tripods have been used for this purpose including tripods having legs with wheeled caster elements. Wheeled casters permit the telescope or camera to be moved about and pointed in different directions as desired by the user. However, such arrangements are inherently unstable. This is especially critical for telescopes. Once proper aim at a target is achieved with a telescope, it becomes very important that the support provided by the tripod become very stable. In the past, tripods with casters have included locking features which lock the wheels and keep them from rotating. Such structures, however, are inherently prone to wobble because wheels do not provide a stable and firm contact with the ground and the parts involved in mounting the wheels generally allow the wheels and/or casters to slip or rotate causing the base supporting the telescope to move thereby disturbing the alignment of the telescope with its target. In addition, as designed most tripods are not structurally rigid. They are not braced properly and tend to wobble. This is unacceptable for precision instruments such as telescopes.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     The present invention provides a stable tripod stand for sensitive optical devices such as telescopes and the like. The tripod may be moved around on wheels which are coupled to casters and when positioned may be secured to the ground to provide an adjustable and highly stable support that significantly reduces the incidence of jitter. The tripod includes a stabilizer member that extends through the casters to selectively engage the ground. The leg members of the tripod have a triangular shape and support links between the platform and the leg members form interlocking triangular supports which reinforce the leg members.  
         [0007]     The foregoing and other objectives, features and advantages of the invention will be more readily understood upon consideration of the following detailed description, taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL DRAWINGS  
       [0008]      FIG. 1  is a front view of the tripod stand of the present invention.  
         [0009]      FIG. 2  is a top view of the tripod stand of  FIG. 1  taken along line  2 - 2 .  
         [0010]      FIG. 3  is a partial bottom view of the tripod stand of  FIG. 1  taken along line  3 - 3 .  
         [0011]      FIG. 4  is a front elevation view of one of the feet of the tripod stand of the  FIG. 1  and its associated caster assembly.  
         [0012]      FIG. 5  is a side view of one of the feet of the tripod stand of  FIG. 4 .  
         [0013]      FIG. 6  is a front view of the tripod stand of  FIG. 4  illustrating the operation of the stabilizer bolt.  
         [0014]      FIG. 7  is a side view of an alternative embodiment of a tripod foot.  
         [0015]      FIG. 8  is a partial top cutaway view of an alternative support platform structure. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     A tripod  10  as shown in  FIG. 1  includes a support platform  12  supported above a ground surface  14  by three leg assemblies  16 ,  18  and  20 . All three of the leg assemblies  16 ,  18  and  20  are identical so reference will be made to only one of the assemblies for illustration purposes.  
         [0017]     Referring to leg assembly  16 , the leg assembly includes a pair of leg members  16   a  and  16   b  coupled to the support platform  12  a predetermined distance apart by pins  22   a  and  22   b  (refer to  FIG. 2 ). The leg members  16   a  and  16   b  are inclined inwardly toward each other and join together at the foot  24  of the leg assembly  16  thereby forming a narrow triangle. In the case of the leg assembly shown in the preferred embodiment, the leg members such as  16   a  and  16   b  are welded to the foot  24 . It is not necessary that this be the case, however, and each of these elements may be separate pieces joined by fastening devices.  
         [0018]     Referring to  FIGS. 4, 5 , and  6 , at the bottom of the foot  24 , there is a caster  26  which includes a pair of wheels  28   a  and  28   b . The foot  24  has a tube  30  which is hollow and is threaded to receive a stabilizer bolt  32 . The stabilizer bolt  32  is hand-turned by a knob  34  and extends through the caster  26 , between the wheels  28   a  and  28   b  and engages the ground  14 . The bolt  32  can be turned until the wheels are lifted clear of the ground  14  if desired. A locking sleeve or nut  36  may be used to tighten the stabilizer bolt after the desired adjustment has been made. The caster  26  includes a body having a threaded core  27  to receive the adjustment bolt  32 . The bolt  32  has a pointed end  32   a  for penetrating the ground surface  14  so as to anchor the tripod  10 .  
         [0019]     Referring to  FIG. 2 , the platform base  12  is roughly hexagonal which permits pairs of leg members, such as leg members  16   a  and  16   b , to be coupled to it a predetermined distance apart. Thus, the pair of leg members  16   a  and  16   b , the foot  24  and the coupling to the platform base  12  form a triangle. The triangular structure of each of the leg assemblies  16 ,  18 ,  20  provides stability in the respective plane formed by each leg assembly triangle.  
         [0020]     To make the legs even more stable, each leg assembly has a complementary pair of support link assemblies,  38 ,  40  and  42  (see  FIG. 3 ). Each assembly is identical so reference will be made to leg assembly  38  for purposes of illustration. Pairs of vertical struts  44   a  and  44   b , which are coupled to the leg members  16   a  and  16   b  by pins  22   a  and  22   b , extend substantially vertically downwardly from the support platform base to a central point  48  directly below the platform base. The central point  48  is a spider connector to which stabilizer link assembles  50 ,  52  and  54  are joined to leg assemblies  16 ,  18  and  20  at their respective feet. From the central point  48 , three stabilizer link assemblies  50 ,  52 , and  54  extend toward each of the feet of the respective leg assemblies  16 ,  18 ,  20  thus forming a pair of stabilizing triangular structures for each of the leg assemblies. Thus, three different triangular structures join each foot of the tripod to the support platform. One triangle is formed by the two leg members  16   a ,  16   b , the foot  24  and the platform  12 . A second triangle is formed by leg  16   a , stabilizer links  50  and the vertical strut  44   a . The third triangle is formed by leg member  16   b , vertical strut  44   b  and stabilizer links  50 . The three interlocking triangles connecting the platform  12  to each of the feet  20 ,  21  and  23  form a very stable, jitter-resistant frame. These triangular structures resist movement in three different directions and thus provide for a very stable platform upon which to place the telescope.  
         [0021]     When the scope is being positioned, the stabilizer bolts are withdrawn as shown in  FIGS. 4 and 5  and the tripod can be moved around on its wheeled casters. When the desired position for the tripod is reached, the stabilizer bolts may be advanced securing the tripod legs to the ground surface as shown in  FIG. 6 .  
         [0022]     Referring to  FIGS. 5 and 6 , the foot  24  has a tube  30  which is internally threaded so as to allow the stabilizer bolt  32  to be screwed into and through the end of the foot  24  into the caster  26 . The locking knob  36  is tapered and has an internal sleeve portion  37  which screws into the receiving tube  30 . When the bolt  32  has been advanced so as to engage the ground surface  14 , the wheels  28   a  and  28   b  are lifted, thus preventing the tripod from any further movement. In order to secure the desired adjustment, the locking knob  36  is tightened until its forward beveled portion engages the similarly beveled upper end of the tube  30 . This locks the stabilizer screw in place.  
         [0023]     An alternative foot member  60  is shown in  FIG. 7 . The foot  60  is joined to each of the legs of the tripod, in this case leg member  49 . The foot member includes a jack screw comprising a hollow sleeve  62  which is internally threaded to receive a threaded stabilizer member  64 . A hand crank  66  turns the threaded stabilizer member  64  through the sleeve  62  until a pointed end  68  engages a ground surface  47  to the satisfaction of the user. A locking nut  61  is then tightened thereby locking the stabilizer member  64  in place.  
         [0024]     The sleeve  62  includes an annular groove  63 . This groove is provided to accept a spring-loaded detent mechanism  65 . The detent mechanism  65  is included as a locking mechanism on a selectively removable caster assembly  67 . The caster assembly  67  includes a pair of wheels  69  (forward wheel not shown). The caster  67  is selectively coupled to the foot by sliding it onto the sleeve  62  until the spring-loaded detent mechanism  65  locks into the annular groove  63 .  
         [0025]      FIG. 8  shows an alternative construction for the tripod support platform which provides additional structural strength and rigidity. A support platform  70  is shaped to have three sides  70   a ,  70   b  and  70   c  arranged at angles of sixty degrees with respect to one another forming an unconnected equilateral triangle. Three cylinders  72   a ,  72   b  and  72   c  are bolted to the edges of sides  70   a ,  70   b  and  70   c  from underneath the platform  70  (bolts not shown). The cylinders each have axles  74   a ,  74   b  and  74   c  thus forming hinges for their respective leg members. The advantage of the structure in  FIG. 8  is that the cylindrical hinges, with their respective axles, form a straight piece of metal joining the ends of the respective leg members. This is structurally more rigid than in the embodiment of  FIG. 2 , which is lighter and requires less metal.  
         [0026]     Several variations of the preferred embodiment may be employed without departing from the spirit of the invention. For example, the casters need not employ a pair of wheels since a single wheel may suffice. Similarly, the platform may have any desired shape. A hexagonal shape is useful for creating the triangles formed by the leg members but other constructions with appropriate pins or rods for forming the narrow ends of the leg member triangles may yield the same result. Also, a single link member may be used to connect the central point to each foot. Fastening devices and methods of attachment of the various links and struts other than those shown may be used if desired.  
         [0027]     The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.