Printer Mechanism Operation

This section describes the Model 3I60 printer mechanism and explains how the printer works. The Model 3I60 printer mechanism features a 18-pin, impact dot printhead for serial printing. The printer mechanism is the main component of the printer and is supported by the other components (the power supply and control circuits). Figure 2-1 shows the Model 3I60 printer mechanism.

Printhead

Paper Bail Assembly

Plunger

TIMING BELT, PF

Connector

Junction

Board

Printhead

Paper Bail Assembly

Plunger

TIMING BELT, PF

Connector

Junction

Board

Motor Epson R220

Tractor Assembly (Front)

PG Motor'

Figure 2-1. M-3I60 Printer Mechanism

Tractor Assembly (Front)

PG Motor'

Figure 2-1. M-3I60 Printer Mechanism

The printer mechanism consists of the following main components:

The printhead is the component that actually prints characters (dot matrix patterns). Printing is performed by striking the pins (arranged in a vertical line) against the surface of the paper and the ribbon. A character is printed by repeating this printing operation in the horizontal direction (as the printhead moves). The printhead includes a head fan and temperature sensor. The head fan also has a thermistor. When the printhead or fan is too hot, the printer stops printing until it cools. (Refer to Section 2.3.9 Printhead Drive Circuit.)

During printing, the paper bail assembly holds the paper under tension so that it is fed smoothly. When paper is loaded or ejected or when the tear off function is executed, the paper bail assembly needs to move up to prevent a paper jam. The plunger moves the paper bail assembly up.

□ Carriage mechanism :

The carriage mechanism moves the printhead in the horizontal direction. The CR motor drives the carriage, with the printhead on it. The CR encoder sensor detects the CR motor speed and carriage position. The CR motor is closed-loop controlled. Because the CR motor is driven at a very high speed, it includes an isolation resistance sensor to detect abnormal resistance. The sensor detects an error if the resistance is less than 2.2 K ohms. (Refer to Section 2.3.4 CR Motor Drive Circuit.)

Because the carriage moves at a very high speed, it would be dangerous if a hand or finger were inserted inside the printer mechanism during printing. Therefore, as a safety measure, when the top cover is opened, the interlock switch cuts the drive voltage to the CR motor to slow down the carriage speed and prevent accidents. A control circuit controls CR motor driver deceleration. (Refer to Section 2.3.4 CR Motor Drive Circuit.) Printing resumes when the top cover is closed.

□ Auto platen gap adjustment mechanism :

The printer mechanism has an automatic platen gap adjustment function that measures the thickness of the paper and provides the appropriate gap between the platen and printhead. The platen gap is adjusted by moving the carriage (and printhead) either forward or backward. Because the front and rear carriage guide shafts which hold the carriage are purposely mounted off-center, the carriage moves as the PG motor rotates the shafts. The PG sensor transmits the amount of movement (= gap) to the control circuit.

□ Ribbon feed mechanism :

The printer's ribbon cartridge contains an endless ribbon. The ribbon feed mechanism takes up the ribbon so that the portion hit by the pins is constantly changing. The RF motor drives the ribbon feed mechanism.

Top View Printer Carriage Mechanism

Figure 2-2. Printer Mechanism Operation 1

Position Sensor

Figure 2-2. Printer Mechanism Operation 1

The CR motor controls printing in the horizontal direction, and the paper feed mechanism controls movement in the vertical direction (line feeding and form feeding). The paper feed mechanism feeds paper vertically. The PF motor drives the paper feed mechanism.

The front, rear, and top PE sensors detect whether paper is present in the paper path, and stop the printer from printing when there is no paper. The printer is equipped with three PE sensors: the front PE sensor at the front tractor, the rear PE sensor at the rear tractor, and the top PE sensor at the paper bail. The pull tractor sensor detects whether the optional pull tractor unit is installed.

The printer is also equipped with a paper jam sensor. The control circuit reads the signals from the sensors and indicates when an error occurs.

□ Tractor select mechanism :

The printer mechanism has two paper entrances: one at the front tractor and one at the rear tractor. By controlling the RF motor, the tractor select mechanism chooses which tractor to use, and power from the PF motor is conveyed via a series of gears. The tractor select sensor detects the selected tractor and signals that information to the control circuit.

Paper

Shaft Guide Front Dfx8500
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Responses

  • Elena
    Where is the paper thickness sensor in a Epson DFX 8500?
    8 years ago

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