Cover for architectural openings

A covering for an architectural opening, comprising:

• an extendable material movable from an extended position for covering the opening to a retracted position for uncovering the opening;
• a drive spool mounted for rotation and operatively connected to a lift spool, with said lift spool being operatively connected to said extendable material, said drive spool configured to rotate in a first direction about a fixed axis of rotation to rotate said lift spool and extend said extendable material, said drive spool configured to rotate in a second direction about said fixed axis of rotation to rotate said lift spool and retract said extendable material, said drive spool and said lift spool being housed in a fixed rail;
• a drive cord having first and second ends, said first end of said drive cord being coupled to said drive spool, said drive cord extending from said drive spool, through a fixed cord emanation point, and then to said second end at a location outside of said fixed rail;
• and
• a compound arcuate guide surface which guides said drive cord between said drive spool and said cord emanation point;
• wherein:
• said guide surface projects radially outwardly away a greater distance from said drive spool where said guide surface is axially aligned with said cord emanation point and tapers to be a smaller radial distance away from said drive spool as an axial distance from said cord emanation point increases;
• pulling on said second end of said drive cord operates said drive spool;
• and
• said drive spool has a tapered cord-receiving surface having a larger diameter at a first axial position than at a second axial position.