Printing apparatus having print line visibility control

A printing apparatus for printing characters along a print line on one face of a printing paper, comprising a type carrier which has a plurality of type characters carried thereon and which is operative to travel along a predetermined path having a portion extending in proximity to and substantially parallel with said print line on the printing paper located on one side of said portion, carrier driving and guiding means for driving and guiding said type carrier to travel along said predetermined path thereof, an inking ribbon to travel along a predetermined path having a portion located between said print line and said portion of the travelling path of the type carrier and extending in proximity to and substantially in parallel with said print line, ribbon drive means for driving the inking ribbon to travel along the predetermined path thereof, ribbon guide means for guiding the inking ribbon to move along the predetermined path thereof, a ribbon casing for feeding the inking ribbon therefrom toward said portion of the travelling path of the inking ribbon and taking up therein the inking ribbon which has been moved past said portion of the travelling path thereof, a plurality of printing hammers located on said one side of said portion of the travelling path of the type carrier and juxtaposed in a row spaced apart substantially in parallel from said portion of the travelling path of the type carrier, and a platen positioned on the other side of and extending along said portion of the travelling path of the carrier, wherein the improvement comprises a support member having mounted thereon members including said type carrier, said carrier driving and guiding means, said inking ribbon, said ribbon drive means, said ribbon guide means and said platen and rotatable about an axis substantially parallel with said print line between a first angular position holding said members in operative positions capable of performing printing operation but intercepting a line of sight between said print line and operator's eyes and a second angular position holding said members out of said operative positions thereof and providing an unobstructed line of sight between said print line and the operator's eyes, cam rollers axially aligned with each other and rotatable about an axis substantially parallel with the axis about which said support member is rotatable, rigid members having fixed positions relative to said support member, said cam rollers being in rollable engagement with said rigid members, respectively, the support member being rotatable between said first and second angular positions depending upon the rotational positions of said cam rollers relative to said rigid members, said cam rollers being in weight bearing relationship to said platen, type carrier, carrier driving and guiding means, ribbon guide means and ribbon drive means through said support member and said rigid members irrespective of the angular position of the support member about said axis thereof, a pulse motor drivingly connected to said cam rollers, and a circular disc rotatable with said cam rollers and formed with a notch in radial direction and electric switch means connected to said pulse motor and including an actuating element engageable with said disc, said notch being located in the disc so that the actuating element of said switch means is in engagement with the disc through said notch when said cam rollers are in angular positions having said support member in said first angular position thereof, said switch means being operative to de-energize said pulse motor when said actuating element is brought into engagement with said disc through said notch.