Paper Feed Mechanism

The paper feed mechanism is composed of a paper feed motor, tractor, paper-end sensor mechanism, pull tractor sensor, plunger mechanism, and paper selection mechanism. Figures 2-6 to 2-8 shows the paper feed mechanism.

After the paper is loaded, it is fed by the tension roller, platen roller, and front/rear tractor. The rotation of the paper feed motor is always transmitted to the tension roller and platen roller (Figure 2-48), but it is transmitted alternately to the front and rear tractors.

The rotation of the paper feed transmission gear is transmitted through the paper feed select gear which is designed to always engage with one of the tractor trains. Which tractor train the tractor select gear engages is selected by the tractor select mechanism.

The paper end sensors always detects whether the paper is loaded or not. In this printer, a total of three paper-end sensors are installed at the front and rear tractors and paper bail.

The front and rear paper-end sensors are incorporated in the sprocket unit. When paper is loaded, the paper pushes the leaf spring so as to block the photo-interrupter. When no paper is loaded, the photo-interrupter is not blocked.

The upper paper-end sensor is attached to the upper paper guide and is used together with the reflection plate on the paper bail. When the paper is loaded, the paper blocks the beam between the photo-interrupter and reflection plate. When no paper is loaded, the beam is not blocked.

The pull tractor sensor monitors whether the optional pull tractor is mounted or not. When the pull tractor is mounted, the tear off function is disabled to prevent paper jams.

Pull Tractor Sensor k gate array in units of f

Bail

E05A38NA

Tension Roller

Upper Paper End Sensor

Platen Gear DAT/1 , Tension

Tractor Select Gear

Platen Gear DAT/1 , Tension

Tractor Select Gear

Figure 2-6. Tension Roller and Platen Roller Operation
Figure 2-7. Front Tractor Operation
Figure 2-8. Rear Tractor Operation
Table 2-6. Paper Feed MotorSpecifications

Type

4-phase 200-pole HB-type stepping motor

Supply voltage

36.5 ±1 VDC

Winding resistance

2.85 ±0.3 ohms

Drive frequency

2610 pps (medium speed mode) 4274 pps (high speed mode)

Excitation system

1-2 phase excitation

Table 2-7. Pull Tractor Sensor Specifications

Type

Micro switch

Supply voltage

5 VDC ±5%

Switch mode

Unmounted -Open (OFF) Mounted -Closed (ON)

Table 2-8. Paper End Sensor Specifications

Sensors at the Front/Rear Tractor

Sensor at the Paper Bail

Detector

Photo-interrupter

Detector

Photo reflector

Output type

Open collector

Output type

Open collector

Supply voltage

5 VDC ±5%

Supply voltage

5 VDC &5%

Signal mode

With paper - HIGH Without paper - LOW

Signal mode

With paper - HIGH Without paper - LOW

There are grooves at both ends of the platen, which are to prevent paper jams caused by paper chips from the sprocket holes in continuous paper or fringes produced when pressing copy paper so that it will not be separated. Since the continuous paper is fed at high speed, the paper chips or fringes could get caught between the ribbon mask and platen and cause a paper jam. The grooves work as margins for the paper thickness.

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