Abstract: A dot matrix printhead is adjusted automatically or manually with respect to a platen in accordance with the thickness of a recording medium on which printing is to occur. When a host data processor sends a control signal to a printer microprocessor to indicate that a recording medium of a different thickness is to be printed, a carrier, which has a first portion supporting the printhead and pivotally and slidably mounted on a front guide rail, is moved so that a shift arm on the carrier engages a right side plate of the frame. This disconnects a ribbon drive motor gear from a ribbon drive gear and moves the ribbon drive motor gear into engagement with a gear train. Rotation of the gear train rotates a gear, which has a threaded shaft and is rotatably supported by a second portion of the carrier slidably mounted on a rear guide rail, to cause pivoting of the first portion of the carrier about the front guide rail to change the gap of the printhead from the platen.

Abstract: In a printing machine having a removable ribbon cartridge, means are provided for conveniently loading and unloading said ribbon cartridge on a support plate. Said means include guide means within the cartridge which cooperate with complementary guide means within the support plate for guiding the cartridge while it is being dropped-in onto the support plate; and lever operated cam/cam-follower means for then shifting the cartridge on the support plate to its final locked position. The cartridge unloading is performed through a reverse lever operation followed by a cartridge pick-up.

Abstract: In a printwheel type of printer using a selection stepper motor for driving the printwheel, means are provided for performing printwheel homing operation upon occurrence of predetermined events. Such an event, is detected and reported to microprocessor means which drive motion means for bringing the printer carriage assembly to a first extreme left position where a stop element fixed relative to the printwheel rotation is made to enter the path of another stop element attached to rotate with the printwheel. Subsequently, the selection stepper motor driving the printwheel is driven for a number of steps at least equal to one motor revolution to ensure reaching inhibition of the printwheel rotation by bringing the rotating stop element into contact with the relatively fixed stop element.

Abstract: In a daisy wheel or rotary print wheel typewriter, a single motor is employed to accomplish both ribbon lift and feed for typewriter ribbon and correction ribbon loaded in a cartridge assembly. A single motor drive moves the cartridge assembly support about an axis to present the typewriter ribbon or the correction ribbon to the print point at the print line. When the elevation of the cartridge assembly about the axis is such to permit normal typing upon the typewriter ribbon, only the feed ratchet for the ribbon is engaged. Alternatively, when the rotation is greater, for example, for typing on the correction ribbon, the added elevation of the cartridge assembly effects disengagement of the normal ratchet feed for the typewriter ribbon while allowing advancement of the correction ribbon.