Inked ribbon advance and reverse mechanism

An improved inked ribbon advance and reverse mechanism for use in a multiple print station printing apparatus, which includes a frame having a base, a first side plate and a second side plate, which are parallelly and oppositely disposed, a drive shaft horizontally disposed between said first and second side plates and rotatably journaled in said sides plates, a movable carrier mechanically coupled to said drive shaft, a print head pivotally coupled to said movable carrier and a pair of platens which are disposed parallel to said drive shaft and each having a print surface of which is in a plane which is substantially orthogonal to the other plane, comprising:

• a. a first ribbon spool onto which an inked ribbon is wound;
• b. a first ratchet wheel the axis of which is orthogonally disposed to said base of said frame and which is axially aligned and fixedly coupled to said first ribbon spool so that said first ribbon spool and said first ratchet wheel rotate together, said first ratchet wheel being rotatably journaled in said frame adjacent to said first side plate;
• c. a second ribbon spool from which an inked ribbon is unwound;
• d. a second ratchet wheel the axis of which is parallelly disposed to said base of said frame and which is axially aligned and fixedly coupled to said second ribbon spool so that said second ribbon spool and said second ratchet wheel rotate together, said second ratchet wheel being rotatably journaled in said frame adjacent to said first side plate and being disposed orthogonally adjacent, but spaced, to said first ratchet wheel;
• e. a sliding member which is a first elongated member having a first flange and a second flange and which is slidably coupled to said frame so that said sliding member slides bi-directionally toward said first and second side plates along said base of said frame;
• f. an elongated pawl member having a first end and a second end and which is fixedly coupled at said first end to said second flange with said pawl member and said sliding member being disposed parallel to each other, a pawl element at said second end and having a first tooth which may engage one of said teeth of said first ratchet wheel and a second tooth being disposed orthogonally adjacent, but contiguous to said first tooth which may engage one of said teeth of said second ratchet wheel;
• g. a mounting member which is fixedly coupled to said movable carrier;
• h. a pivot pin which is fixedly coupled to said mounting member;
• i. a lever arm, which is an elongated member having a first end and a second end and a first groove and a second groove which are spaced apart from the center of said elongated member so that one of said first and second grooves may be pivotally coupled to said pivot pin in order that one of said first and second ends of said lever arm may push against one or the other of said first and second flanges of said sliding member, respectively causing said first and second ratchet wheels to rotate, respectively;
• j. resiliently coupling means for resiliently coupling said lever arm to said mounting member;
• and
• k. a spring which resiliently couples said first side plate to said pawl member in order to resiliently bias said sliding member so that said sliding member is biased toward a substantially mid position of its entire movable distance.