Two piece expandable loose leaf binder
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to loose leaf binders and more particularly, to an expandable loose leaf binder having a two piece configuration. 
     2. Summary of the Prior Art 
     As has been long known, it is more convenient and efficient to secure the plurality of loose sheets of paper and the like in a binder. The sheets being bound in a loose leaf type arrangement can constitute paper, plastic, and the like of many forms, such as, for example, the sheets of a computer printout. In the past binders for securing loose leaf sheets have constituted a multitude of designs which suffer from several shortcomings. For example, several binder configurations employ a fixed width such that its thickness is virtually the same whether a few sheets are present or a large number are being bound. In addition, known designs of binders are cumbersome to be expanded as traditional sheets are added. Attempts have been made to improve binders so that they are expandable to accommodate various numbers of sheets or to permit the addition of removal of sheets as needed. Known variable thickness binders are inconvenient to use and have not provided a finished look in any sheet capacity. Accordingly, it is desirable to provide an improved variable capacity binder that is easy to use and can accommodate a large number of sheets in an attractive manner. 
     SUMMARY OF THE INVENTION 
     It is therefore an objective of the invention to provide a two piece adjustable binder providing ease of attachment with an economical design. The expandable binder herein disclosed includes a back cover having a flap provided with a plurality of apertures to accommodate variable thicknesses of sheets being secured and providing an attractive covered edge. One embodiment of the binder of the invention can secure up to fifteen hundred sheets and is expandable from one inch to six inches. In all thicknesses of the binder, it has a finished look covering the back edges of all the sheets being secured. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a back perspective view of the expandable loose leaf binder of the invention; 
     FIG. 2 is a perspective view of the inside surface of the back cover of the loose leaf binder of FIG. 1 in a flat configuration; 
     FIG. 3 is a top perspective illustration of the back cover having splines for retention of sheets being retained; 
     FIG. 4 is a top perspective view of the inside of the back cover of the loose leaf binder of FIG. 3 having a plurality of loose leaf sheets affixed to the spline of FIG. 3; 
     FIG. 5 is a top perspective view of the back cover of FIG. 5 in which the flap of the back cover is folded over in an adjusted position of the loose leaf sheets shown in FIG. 4; and 
     FIG. 6 is a top perspective view of the front cover being retained to the back cover as shown in the configuration of FIG. 5. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1 to 6 there is illustrated the expandable loose leaf binder of the invention, generally designated by reference numeral 2. The expandable binder 2 includes a back cover member 4 having a flexible flap 4a and a front cover member 6. As seen in FIG. 1, the loose leaf binder 2 secures a plurality of sheets or leaves 8 with the back edge 8a being covered in all thicknesses by a flexible or pliant flap 4a of a plastic material forming the edge section. The back cover portion 4b is rigid in construction and may be covered with a plastic material in a conventional manner. The flexible flap 4a is provided with a plurality of apertures 10, such as eleven or similar number, disposed in two parallel rows extending along an axis perpendicular to the free end edge 10a of flap 4a. The flap 4a is integrally retained to the back cover 4b by a flexible section 14 folded in superimposed relationship in two portions 14a and 14b as best shown in FIG. 2. A metal strip 16 extending substantially the height of the cover is affixed to intermediate section 14a. The metal strip 16 includes a pair of raised edge portions 18 and is retained by three fastener elements 20 securing metal strip 16 and intermediate sections 14a and 14b in unitary superimposed configuration. The metal strip 16 and intermediate section 14 include a pair of insertion holes 22 being in alignment with the axis of the rows of apertures 10. 
     As shown in FIGS. 1 and 6, the front cover 6 includes a rigid cover portion 6a and a flexible inner edge flap 24 extending the height of the cover portion 6a. A metal strip 26 is retained by three fasteners (not shown) to retain the metal strip 26 to the flexible flap 24 as seen in FIG. 6. The metal strip includes rail like elements 26a which mount a pair of clips 28 in retained relationship for sliding movement along the spine 26. The clips 28 act to retain the exposed end portion 30a of plastic retainer elements 30 in a secured downward position beneath the clips (secured position not shown) in a conventional manner. 
     The technique for binding the loose leaf sheets in the variable width binder 2 is shown in FIGS. 2 to 6. As seen in FIG. 2, the retainer elements 30 are inserted through three punched holes 22 and are pulled up to a vertical position as depicted in FIG. 3. Sheets of prepunched paper 8 and the like are placed on posts 30 on the inside of back 4 as seen in FIG. 4. The flap 4a is then folded over, such that the posts 30 will pass through a pair of the apertures 10 that matches the width of the sheets 8 being retained. The cover 6 is then placed on the sheets through holes 32 within the metal strip 26 and flap 24. The exposed ends 30a of the posts 30 are bent inward and the tabs 28 are moved over the exposed ends 30a to secure the front cover 6 to the back cover 4a. When loading the sheets with leaves 30 being retained by posts 30 and it is anticipated that front pages will be added later, then page 1 is initially the top sheet of the sheets 8 as seen in FIG. 6. Alternatively, if back pages will be added later, the first sheet at the top of FIG. 6 would be the back pages so that additional back pages could be easily accommodated and realignment of a particular aperture 10 with the posts 30 is possible as additional thickness are added.