Abstract:
In binoculars, a plastic cover contains therein substantially all of the portions of the binoculars except the openings of holding cylinders and the operating knob. The cover comprises left and right cover members rotatable about a central shaft integrally with the left and right holding cylinders, respectively.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to binoculars, and more particularly, to the outer shell portion of binoculars. 
     2. Description of the Prior Art 
     In conventional binoculars, the optical systems and the sliding mechanisms for the optical systems have been accommodated within a body formed of aluminum alloy diecast into a predetermined shape substantially complementary to the outer configuration of the binoculars. The external appearance of the binoculars has been determined by such processes as plating the body of aluminum alloy or applying material such as artificial leather to the holding portion. Therefore, physical blows or the like have been directly imparted to the body readily to damage the same, and once so damaged, the body has been difficult to repair. Moreover, the plating often eventually peeled off due to wear or friction and this too has been difficult to repair. 
     SUMMARY OF THE INVENTION 
     We have conceived and contribute by the present invention binoculars of a construction according to which we are able to overcome the above-noted difficulties and disadvantages peculiar to the conventional binoculars and to provide binoculars having a body which is not easily damaged, and an outer shell which readily permits repair. 
     There has thus been outlined rather broadly the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of the invention. It is important, therefore, that the claims be regarded as including such equivalent constructions as do not depart from the spirit and scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Specific embodiments of the invention have been chosen for purposes of illustration and description, and are shown in the accompanying drawings, forming a part of the specification wherein: 
     FIG. 1 is a cross-sectional view of an embodiment of the present invention; 
     FIG. 2 is a cross-sectional view taken along line A--A in FIG. 1; 
     FIG. 3 is a cross-sectional view taken along line B--B in FIG. 1; 
     FIG. 4 is a perspective view of the cover shown in FIG. 1; and 
     FIG. 5 is a perspective view showing another embodiment of the cover. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 to 3, there is shown an embodiment of the present invention wherein an optical system including an objective lens 1a and an eyepiece 1b and an optical sytem including an objective lens 1a&#39; and an eyepiece 1b&#39; are parallel to each other and are accommodated within holding cylinders 2 and 2&#39;, respectively. A central shaft 3 lies midway between the cyllinders 2 and 2&#39;, which cylinders are rotatably coupled to the central shaft 3 by coupling means 4 and 4&#39;. 
     A sliding mechanism 5 may be of the well-known type and has arms 5a and 5a&#39; linerally movable axially of the central shaft 3 upon rotation of an operating knob 6. The arms 5a and 5a&#39; are coupled to a portion of the objective lenses 1a and 1a&#39; by means (not shown) and distance adjustment may be accomplished by moving the arms 5a and 5a&#39; in the direction parallel to the optic axis. Each holding cylinder 2 or 2&#39; and each coupling means 4 or 4&#39;, respectively, may be formed integrally by diecasting aluminum alloy or like material. Members 7, 8, 9 and 10, appearing chiefly in FIG. 2, are covers formed of plastic and cover the outer surfaces of the holding cylinders 2, 2&#39;, the central shaft 3, the coupling means 4, 4&#39; and the sliding mechanism 5. These covers 7, 8, 9 and 10 are preformed into a predetermined outer shell shape. The lower covers 7 and 10 are provided with projections 7a and 10a formed with threaded holes and tabs 7b and 10b for fitting. The covers 9 and 8 opposed to the covers 7 and 10 have projections 9a, 8a and 9b, 8b formed at locations opposed to the projections 7a, 10a and the tabs 7b, 10b, the projections 9a and 8a being formed with holes. These covers 7, 8, 9 and 10 are applied over the holding cylinders 2, 2&#39;, the central shaft 3, the coupling means 4, 4&#39; and the sliding mechanism 5 by fitting together the tabs 8b, 10b and 7b, 9b and fitting the projections 7a, 10a of the covers 7, 10 into holes 4a, 4a&#39; formed in the coupling means 4, 4&#39; and fitting the projections 8a, 9a of the covers 8, 9 into holes 4b formed in the coupling means 4, and by threading screws 11 into the aforementioned threaded holes of the projections 7a, 10a. Designated by 12 is a false plate for covering the heads of the screws. 
     One end of each of the covers 7, 8, 9 and 10 are formed with a curved surface portion 7c, 8c, 9c, 10c (only 9c does not appear in the drawing). These curved surface portions 7c, 8c, 9c, 10c are intended to prevent the internal mechanism including the central shaft 3 from being exposed when the left and right holding cylinders 2, 2&#39; are rotated about the central shaft 3 of the binoculars to adjust the eye span of the binoculars. That is, in the position of FIG. 2, the curved surface portion 8c formed in the cover 8 is accommodated within and overlapped by the cover 9 lying on the same side and is not exposed, while the curved surface portion 7c formed in the cover 7 is exposed to cover the lower side of the coupling means 4 fitted to the central shaft 3. On the other hand, when the left and right holding cylinders 2, 2&#39; are rotated downwardly about the central shaft 3, the curved surface portion 8c  becomes exposed to prevent the internal mechanism including the central shaft 3 from being exposed. 
     The binoculars of the present invention is excellent in shock resistance because the internal mechanism thereof is always protected by plastic covers. Also, according to the present invention, only the necessary minimum portion supporting the optical systems and the sliding mechanism thereof may be formed by diecasting; and moreover, the plastic forming the covers is light in weight and the simple detachability of the covers leads to an advantage that the covers, if damaged, may be readily replaced by new ones. Further, if a cover such as cover 90 configured as shown in FIG. 5 which differs from the cover 9 of the present embodiment as shown in FIG. 4 or several types of covers differing in color from the cover of FIG. 4 are prepared, the user will be able selectively to use covers of his favorite color and shape while using the same main body. Additionally, as shown in the illustrated embodiment, the cover is formed of a plurality of pieces corresponding to the left and right holding cylinders and therefore, adjustment to the eye span can be accomplished without the unsightliness of the exposed internal mechanism. 
     I believe that my novel binocular construction will now be understood and that the several advantages thereof will be fully appreciated by those persons skilled in the art.