Abstract:
Two telescopic bodies are held together by a collapsible bridge which is hinged centrally and along the side connections between the bridge and the telescopic bodies. The three hinge axes are parallel to the optical axes of the bodies. Three or more interlocking hole elements on each hinge assure body alignment, and the side hinge pins are retained by knots in the carrying cord. The folded thickness of the telescope substantially equals the diameter of a single telescopic body.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to a binocular telescope of the type used at, for examples, the theatre, sporting events, bird watching and the like, and more particularly to a binocular telescope having a hinged and collapsible bridge whereby the binocular telescope is folded to a reduced size which is easily inserted into a clothing pocket. It is desirable that binocular telescopes should occupy a minimum amount of space when not in use. Therefore, several solutions have been propounded in the prior art in which the two telescopic bodies or monoculars can slide together to facilitate storage in a pocket. 
     It is known in the prior art to form a bridge linking the two telescopic bodies so that the middle planes through the bridge form a &#34;Z&#34; with the planes passing through the telescopic bodies and the swivel axis when the instrument is in its closed or collapsed condition. In this prior art solution to the problem of binocular size, the collapsed binocular telescope is substantially thicker than any individual telescope. As a consequence this binocular telescope when collapsed can only be stored in a pocket with difficulty. Such a binocular telescope is shown in the German Pat. DT-GM No. 7536 330. 
     In another binocular telescope of the prior art disclosed in German Pat. DT-OS No. 2424 792, a metal bridge is provided, against which the two telescopic bodies hinge on the same side but in the opposite directions. In this instance, the thickness of the folded telescopic unit, which determines the size of pocket in which it will be accommodated, is approximately the total of the thickness of the metal bridge plus the diameter of the telescope. 
     In another known design of the prior art, there is provided only one bending point on the bridge, and the telescope is folded in proportion to the strength of the bridge so that when folded, the strength of the telescopic bodies themselves is not exceeded. This solution, however, constitutes only apparent progress since it makes little sense to produce the telescopic bodies stronger than is required by the stresses normally passing through them. The flattening of a telescopic body causes the corresponding wall to draw closer to the stress path, thereby producing reflected stresses unless the telescopic bodies are enlarged to correspond to the flattening, which otherwise would not be required by the stress path per se. 
     What is needed is a binocular telescope which, when not in use, is folded into a small configuration without inducing undesirable stress loads in the telescopic bodies. 
     SUMMARY OF THE INVENTION 
     Generally speaking, in accordance with the invention, a foldable binocular telescope especially suited for placement in a pocket, is provided. The binocular telescope of this invention, when in the closed or folded state is not thicker, or is only slightly thicker, than the telescopic bodies. In the binocular telescope of this invention two telescopic bodies are held together by a collapsible bridge which is hinged centrally and along the side connections between the bridge and the telescopic bodies. The three hinge axes are parallel to the optical axes of the bodies. Three or more interlocking hole elements on each hinge assure body alignment, and the side hinge pins are retained by knots in the carrying cord or sling. The folded thickness of the binocular telescope of this invention substantially equals the diameter of a single telescopic body. 
     Accordingly, it is an object of this invention to provide a binocular telescope which is foldable when not in use. 
     Another object of this invention is to provide a binocular telescope which is foldable and has a folded thickness substantially equal to the diameter of the telescopic body. 
     A further object of this invention is to provide a binocular telescope which provides excellent alignment between the two telescopic bodies. 
     Still another object of this invention is to provide a binocular telescope which folds easily yet provides friction in the hinges whereby the unfolded condition is easily maintained. 
     Still other objects and advantages of the invention will in part be obvious and in part be apparent from the specifications. 
     The invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a perspective view of the binocular telescope of this invention in the open or unfolded condition; 
     FIG. 2 is a back elevational view of the binocular telescope of FIG. 1 in the folded or closed condition. 
     FIG. 3 is an exploded, partial perspective view to an enlarged scale of the binocular telescope of FIG. 1; and 
     FIG. 4 is a sectional view of the components of FIG. 3 shown in an assembled condition. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the Figures, the binocular telescope of this invention has two telescopic bodies 5, 6 which are joined together by the bridge 1. The left telescopic body 5 is connected to the bridge 1 at the hinge 21 and the right telescopic body 6 is connected to the bridge 1 at the right side hinge 20. The bridge 1 is comprised of the left bridge segment 17 and the right bridge segment 18 joined by the middle hinge 19. The folding axis 4 for the bridge runs parallel to the optical axes 2, 3 of the telescope bodies 5, 6 respectively. The breaking axis 4 is at the midpoint of the bridge 1 between the side hinges 20, 21 and the bridge segments 17, 18 oscillate or pivot about the central breaking axis 4 when torque is applied. The hinge pin 16 connects the left and right bridge segments 17, 18 along the central breaking axis 4 by passing through holes in generally circular tabs 7, 8, 9, and 10 in the right bridge segment 18 and through similar holes in tabs 11, 12, 13, 14, on the left bridge segment 17. The tabs 7 and 8 on the right bridge segment 18 alternate and interlock with the tabs 11 and 12 on the left bridge segment 17, and the tabs 9 and 10 on the right bridge segment 18 alternate and interlock with the tabs 13 and 14 on the left bridge segment 17. Thus a precision fit is provided for rotation of the bridge segments 17, 18 about the axis 4. To collapse or fold the binocular telescope of this invention the central hinge 19 is depressed into the space between the telescope bodies 5, 6, and as best seen in FIG. 2, the telescope bodies 5, 6 are rotated inwardly toward the folded bridge 1. The distance between the middle hinge 19 and the side hinges 20, 21 allows for the binocular telescope to fold without any, or very little, extension of the hinge 19 below (FIG. 2) the lower edges of the telescopic bodies 5, 6. In other words, the thickness of the folded binocular telescope of this invention substantially equals the diameter d of the bodies 5, 6. 
     By providing the numerous interlocking tabs in the middle hinge 19, a friction free condition is created which insures that even after long usage the hinge does not become loose or wobbly. A highly aesthetic appearance design is provided by having the central hinge 19 at an equal distance from both side hinges 20, 21. 
     Because all of the bending or folding of the telescope of this invention is done along hinge lines, no bending stresses are induced in the components and accordingly the telescopic bodies 5, 6 and the bridge segments 17, 18 are made predominantly from synthetic materials, e.g. plastic. However, it must be recognized that in a high quality binocular telescope, the two telescope axes 2, 3 must run parallel to each other with a high degree of tolerance which is measured in minutes of an angle. Thus the requirements for the stability of the bridge 1 and the degree of parallelism of the axes 2, 3, 4 are very high. For this reason those parts of the bridge 1 which are made from synthetic materials are coated with metal reinforcements (not shown) by extrusion techniques. To further the stability of the hinges at least one of the parts in the hinge has at least three hinge holes. In the description above, the left and right bridge segments 17, 18 each have four tabs with holes in order to make a stable hinge connection. The outermost tabs and holes on the bridge elements 17, 18 function as guiding and aligning elements. Thus tabs 7 and 10 on bridge element 18 provide for alignment of the axes and the inner tabs 8 and 9 are fitted for the production of the required friction which makes for smooth rotation of the hinge and allows the telescope to be static in any folded position. The outer tabs on the left bridge segment 17 also serve for alignment of the axes and the inner tabs for the production of the required friction forces. The outer tabs and holes are spaced as far apart on the bridge elements as is physically feasible. 
     FIGS. 3 and 4 illustrate the left hinge 21. The right hinge 20 is of similar construction. The telescopic body 5 includes the integral tab or hinge eye 22. The hinge eye 22 is the most forward, that is, most remote from the eyepiece 35, and has a blind hole 22a therein. The telescopic body 5 further includes two additional tabs 23, 24 having holes passing therethrough. 
     Barrel elements 25, 27 having aligned holes passing therethrough are integral with the left bridge element 17. When assembled (FIG. 4) the barrel element 25 fits between the two tabs 23, 24, and the barrel element 27 fits between the tabs 22, 23 with the holes in the tabs and in the barrel elements in alignment. The single hinge pin 28 passes through the entire length of the hinge and seats at one end in the blind hole 22a. There is a tight but rotatable fit between the barrel elements on the bridge element and the tabs on the telescopic body. Nevertheless, it should be noted that the disk 26 is positioned between one surface of the tab 23 and a surface of the barrel element 25. The compression spring 29 is located in an enlargement of the through hole in the tab 23. The spring 29 urges the disk 26 against the barrel element 25 and produces the necessary friction between the hinge parts connected to each other so that the binocular telescope will remain in any position of folding set by the user. 
     Access to the hinge pin hole in the tab 24 is provided through the side opening 33 in the tab 24. The knotted end 31 of the carrying sling or cord 32 rests within the opening 33 and the cord 32 is threaded through the lower portion of the through hole in tab 24. Thus an aesthetically pleasing point of attachment is provided for the carrying sling or cord 32 and the knot 31 of the carrying cord 32 provides a stop which prevents the hinge pin 28 from sliding out of engagement with the tab 22. 
     In assembling the hinge joint between the bridge elements and the telescopic bodies, the barrel elements on each bridge segment are inserted between the tabs on the telescopic bodies. Then the hinge pins 28 are slid in through the aligned hole openings starting from the back near the eyepiece 35 until the end of the hingepin 28 is seated in the blind hole 22a.  Finally, the carrying sling or cord 32 is threaded through the opening in the tab 24 wherefrom it exits to the side opening 33. The knot 31 is then made at the end of the sling or cord 32 and the knot is pulled into the opening 33 to the position as best seen in FIG. 4. 
     It will thus be seen that the objects set forth above among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.