Printer Mechanism

This printer mechanism consists of Printhead, Paper feed mechanism, Carriage movement mechanism, Tractor feed mechanism, Platen gap adjustment mechanism, Ribbon feed mechanism, PF motor, CR motor, detectors, and so on.

2.2.1 Printhead

The printhead prints data from the control board on paper using the ink ribbon. The printhead is mounted on the carriage unit.

2.2.2 Paper Feed Mechanism

The paper feed mechanism picks up paper and transports it to the printhead, then ejects the paper step by step or continuously driven by the PF motor. PF motor drives the paper feed mechanism gears and the platen roller. The top of form and paper out condition are detected by the front and rear PE detector, respectively.

2.2.3 Carriage Movement Mechanism

The carriage movement mechanism carries the carriage unit left and right along the CR guide shaft and mechanism frame, and stops it at any position for printing. It is driven by torque sent from the CR motor via the timing belt. Home position is detected by the HP (home position) detector at power on and CR motor phase changing timing.

2.2.4 Tractor Feed Mechanism

The tractor feed mechanism feeds continuous paper to the printhead and ejects it. Torque from the PF motor is transferred to the tractor unit via the release mechanism in the paper feed mechanism. The release lever in the release mechanism switches torque from the PF motor between cut sheet feeding and continuous paper feeding. This printer is equipped with several tractor feeding methods (front / rear push tractor feeding, front / rear push & pull tractor feeding and front / rear pull tractor feeding), which is selected according to the tractor unit setting positions and the lever positions. The tractor detector detects the release lever setting position, for cut sheet feeding or continuous paper feeding.

2.2.5 Platen Gap Adjustment Mechanism

The platen gap (the gap between the platen and the printhead) adjustment mechanism consists of CR guide shaft, parallelism adjustment bushing, PG adjust lever and PG detector. PG adjust lever is attached to the left side of the CR guide shaft. The bushings are attached to the both sides of the frame. As the both sides of CR guide shaft are eccentric toward external form of them, printhead approaches or recedes from the platen roller as the PG lever turns forward or backward. PG detector detects PG lever position. If the lever is set to a position between "2" and "6", the printer is in the copy mode.

2.2.6 Ribbon Feed Mechanism

The CR motor drives the ribbon feed mechanism via the timing belt. The ribbon feed mechanism has the sun and planetary gear system. No matter the carriage unit is driven left and right, the ink ribbon is driven in one direction.

Figure 2-3. Printer Mechanis Outline

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