Vernier carriage control

An ultrafiche reader apparatus of the type which includes a light system and a projection system for projecting a magnified image of a selected one of a plurality of ultrafiche film frames therebetween onto a reference surface, an improved ultrafiche carriage assembly for positioning a desired one of said film frames between the light system and the projection system comprising:

• a pair of spaced apart and substantially parallel glide members;
• first and second spaced apart and substantially parallel glide bars extending across said pair of glide members and transverse to said glide members, said second glide bar including a rack on a portion of at least one side thereof;
• a friction surface extending alongside of each of said glide members;
• first and second side supports for coupling said first and second glide bars together in fixed spaced apart relation, one of said side supports including guide openings for receiving one of said glide members, the other of said side supports including a portion resting upon the other of said glide members, and each side support including a rotatable wheel communicating with one of said friction surfaces;
• an ultrafiche holder adapted for receiving an ultrafiche and extending across said first and second glide bars and including a rotatable pinion coupled to said rack of said second glide bar;
• an index grid having a location indicia for each film frame on the ultrafiche;
• a location indicator coupled to each said side support in spaced relation to said grid, said ultrafiche and the light and projection systems to indicate on said grid the accurate position of said film frames in a first direction;
• and
• an indicator coupled to said ultrafiche holder in spaced relation to said grid, said ultrafiche and the light and projection systems to indicate on said grid the accurate position of said film frames in a second direction;
• whereby as said friction wheels are rotated said ultrafiche holder is caused to glide in guided movement along said first and second members in a first direction and as said pinion is rotated said ultrafiche holder is caused to glide upon said glide bars in said second direction transverse to said first direction while said side support indicators indicate the accurate position of said film frames for said first direction of movement and said holder indicator indicates on said grid the accurate position of said film frames for said second direction of movement.