Error-correcting typewriter

Claim 1

AN ERROR CORRECTING TYPEWRITER COMPRISING CHARACTERPRINTING MECHANISM INCLUDING PRINTING CONTROL KEYS; A PAPER SUPPORT MECHANISM; SPACING MEANS FOR STEPWISE MOVING SAID MECHANISMS RELATIVE TO ONE ANOTHER IN A FORWARD DIRECTION IN RESPONSE TO OPERATION OF SAID KEYS TO ACCOMPLISH PRINTING OF A LINE OF CHARACTERS; RIBBON VIBRATOR MEANS ACTUATED BY THE PRINTING CONTROL KEYS TO BRING A RIBBON FIELD MOMENTARILY INTO OPERATIVE POSITION UPON ACTUATION OF EACH OF SAID PRINTING CONTROL KEYS; A PRINTING RIBBON AND A PRINT-OBLITERATING RIBBON CARRIED BY SAID VIBRATOR MEANS FOR SELECTIVE PRESENTATION IN IMPRESSING POSITION; RIBBON FIELD-SELECTING MEANS FOR CONTROLLING THE MOTION OF THE VIBRATOR MEANS TO SELECT THE PARTICULAR RIBBON THAT IS THUS BROUGHT INTO IMPRESSING POSITION; BACKSPACE DRIVE MEANS FOR STEPWISE MOVING SAID MECHANISMS RELATIVE TO ONE ANOTHER IN THE BACKWARD DIRECTION IN LETTERWIDTH INCREMENTS; A PAIR OF BACKSPACE KEYS BOTH CONNECTED TO OPERATE SAID BACKSPACE DRIVE MEANS; CONNECTIONS BETWEEN SAID BACKSPACE KEYS AND SAID FIELD-SELECTING MEANS; OPERABLE TO SHIFT THE FIELD-SELECTING MEANS BETWEEN POSITIONS RESPECTIVELY CORRESPONDING TO THAT BACKSPACE KEY WHICH WAS LAST OPERATED; MEANS FOR FEEDING SAID PRINTING RIBBON THROUGH SAID VIBRATOR MECHANISM UPON EACH OPERATION OF SAID PRINTING CONTROL KEYS; MEANS FOR FEEDING SAID PRINT-OBLITERATING RIBBON THROUGH SAID VIBRATOR MECHANISM UPON EACH OPERATION OF SAID PRINTING CONTROL KEYS; AND MEANS CONTROLLED BY SAID RIBBON FIELD-SELECTING MEANS FOR SELECTIVELY DISABLING THE FEEDING MEANS FOR ONE OF SAID RIBBONS.