Abstract:
A movable index mounted on a base sheet for reciprocal movement which movement is controlled, guided and limited by track means and track-follower means.

Description:
BACKGROUND OF THE INVENTION 
     Movable information sheet display arrangements are old (U.S. Pat. Nos. 694,001, 854,069, 2,291,573 and 2,452,231). ln addition, information displays movable from a concealed position to a display position are old (see U.S. Pat. No. 694,001). Prior housing arrangements for containing index means and the track arrangements for controlling and limiting such index movement have not been found to be satisfactory. 
     SUMMARY OF THE INVENTION 
     Broadly, the present invention comprises a stationary base sheet having spaced-apart deflectable projections and a reciprocating index sheet positionable on the base sheet for movement back and forth thereon such index sheet having spaced-apart slots for receiving the base sheet projections so that the projections guide the reciprocal index sheet and function as stops to limit such reciprocation. 
     It is a feature that the base sheet is covered with a cover sheet which cover sheet together with the base sheet act as opposing guide sheets to house, guide and control the interleaved index sheet. The cover sheet also deflects and holds deflectable projections in their deflected positions. 
     It is also a feature that projections are formed as partial cutouts of the base sheet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the movable index unit with the cover raised position ready for assembly; and 
     FIG. 2 an exploded perspective view of the unit with the base sheet and cover in an open position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIGS. 1 and 2, movable index unit 10 includes stationary base sheet 11 having top or inside planar surface 11a and bottom or outside planar surface 11b (not shown) and cover sheet 12 attached along fold line 13 and separate movable index sheet 14. Sheet 11 also has forward edge 11f and rearward edge 11r. Cover sheet 12 includes flap 16 folded along fold line 17 when assembled and tucked into base sheet slot 18 entering from a direction toward surface 11b (a portion of flap 16 appearing as dotted line 21; FIG. 2). Base sheet 11 and cover sheet 12 carry punch holes 22 for use with ring binders or other punched sheet holders. All portions of unit 10 are preferably made from paper, cardboard or plastic sheet stock. 
     Base sheet 11 has cutout flexible projection tabs 24, 26 which are insertable into index elongated slots 15, 20 of index sheet 14. Track slots 15, 20 which are cut all the way through sheet 14 have slot ends 15a, 15b and 20a, 20b. Base sheet 11 is rectangular with forward edge 11f and rearward edge 11r and index sheet has forward edge 14f and rearward edge 14r. Projections 24, 26 are bent over to lie flat as illustrated by dotted line 27 of FIG. 1 or partially deflected in response to the positioning of cover 12 as further explained. Index sheet 14 has index portion 31 with index information printed or written on it such as &#34;index&#34;, &#34;1&#34;, &#34;2&#34; and &#34;3&#34;. 
     In assembly and operation of unit 10, index sheet 14 is placed on surface 11a of base sheet 11 with tabs 24, 26 threaded through elongated slots 15 and 20. Cover sheet 12 is then flded down and flap 16 wrapped around base sheet 11 and finally flap 16 is threaded through slot 18 from a direction toward surface 11b to complete assembly. Projection tabs 24, 26 are caused to deflect and fold down to a horizontal position as shown by dotted lines 27 or some lesser deflected position. As so assembled, index sheet 14 is ready for reciprocation by sliding sheet 14 in direction of arrow A (FIG. 1). Parallel slots 15, 20 with slot ends 15a, 15b, 20a, 20b are of selected length and position so that index sheet 14 is limited in movement by slot ends 15a, 15b, 20a, 20b engaging respective track-follower tabs 24, 26. Preferably, index sheet 14 reaches one limit to its motion when nested fully within and between base sheet 11 and cover sheet 12 wherein forward edges 11f  and 14f are adjacent. The other limit occurs when index portion 31 is extended sufficiently beyond base sheet 11 and cover sheet 12 for complete index viewing. Tabs 24 and 26 in their track slots 15, 20 prevent complete removal of index sheet 14 from unit 10.