Star Micronics TSP400 technical manual Printer Mechanism, Thermal Head, Paper-Feed Mechanism

THEORY OF OPERATION

3.Printer Mechanism

3-1. Thermal Head

The TSP400 printers employ thermal line printing. The thermal head consists of a horizontal line of 640 heat elements. These elements print one line of dots at a time as the paper passes over the head. The head is fixed in position; only the paper moves.

The printer prints a dot by heating the corresponding heat element. The heated element causes a chemical reaction in the coloring layer of the thermal paper, resulting in the formation of a visible dot.

Thermal head

Heat element

Coloring layer

Thermal paper

Printed point

Platen

Fig. 2-13 Principle of Thermal Printing

3-2. Paper-Feed Mechanism

The paper-feed mechanism is comprised of the paper-feed motor, gear train, platen, and thermal head. The paper-feed motor drives the gear train, which in turn rotates the platen. The platen carries the thermal paper past the thermal head.

The paper-feed motor is a PM (permanent magnet) type, 4-phase 48-pole step motor. A single step feeds the paper approximately 0.125mm.

Thermal head

Thermal paper

Platen Gear train

Paper-feed motor

Fig. 2-14 Paper-Feed Mechanism

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