Page: 31Service Guide ML390/391Chapter 2 Principles of Operation2.4.03 Ribbon Drive Mechanism / OperationNOTE:The ribbon drive gear assembly is secured to the top of the spacing motor assembly by the four claw tabs.The ribbon drive mechanism drives the ribbon in sync with the spacing operation. The mechanism isdriven by the spacing motor.The ribbon drive mechanism consists of the following items.· Ribbon Drive Gear Assembly· Ribbon GearThe gear is attached to the spacing motor.· Ribbon CartridgeRibbon CartridgeA uni-directional feed, continuous ribbon is used. The ribbon is replenished by a built-in ink tank in theribbon cartridge.Ribbon Feed OperationAs the spacing motor rotates, the ribbon gear (on the spacing motor shaft) turns the drive gear in theribbon cartridge via the ribbon drive gear assembly. As a result, the ribbon is moved.In bi-directional printing, the ribbon gear rotational direction reverses each time the direction of thecarriage movement reverses. In this case, the gears in the ribbon drive gear assembly move the positionof an intermediate idler gear, causing the ribbon to feed in one direction.
