Seiko LTPH245, Техническое описание

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1.2 DESIGN AND HANDLING PRECAUTIONS
To maintain the initial level of performance of the printer and to prevent future problems from occurring,
observe the following precautions.
1.2.1 Design Precautions

If too much energy is applied to the thermal head, it may overheat and become damaged.
Always use the printer with the specified amount of energy.
Do not apply a pulse of 2V and 20 nsec or higher to each signal terminal of the thermal head.

Use C-MOS IC chips (74HC240 or equivalent) for interfacing the CLK, LATCH, DAT and DST
signals of the thermal head.

When turning the power on or off, always DISABLE (put in “Low” state) the DST terminals.

To prevent the thermal head from being damaged by static electricity:

Fix the printer to the Frame Ground (FG) with the FG connector as shown in Figure 7-2 .

Connect the GND terminal (SG) to FG through 1 M

resistor so that the electric potential
of the SG of the thermal head and the FG of the printer are equal.

Keep the Vp power off when not printing to prevent the thermal head from becoming
electrically corroded. In addition, design the printer so that the signal GND of the thermal head
and the frame GND of the printer mechanism become the same electric potential.

Wire resistance should be 50 m

or less (however the less the better) between the power
supply and the Vp, and the GND terminals on the thermal head controller. Maintain a
considerable distance from signal lines to reduce electrical interference.

The surge voltage between Vp and GND should not exceed 10 V.

As a noise countermeasure, connect the capacitor noted below between the Vdd and GND
terminals near the thermal head control connector.
Vp

GND: approximately 10

F
Vdd

GND: approximately 1

F

When turning the power on or off, perform the Vp and Vdd simultaneously or in the order of 1)
and 2) as follows:
At power ON:
1) Vdd (5 V)

2) Vp
At power OFF: 1) Vp

2) Vdd (5 V)

Always monitor the output of the platen position sensor and out-of-paper sensor. Incorrect
activation of the thermal head may damage and reduce the longevity of the thermal head and
the platen.
Design the outer case so that the out-of-paper sensor is not affected by light from outside.
Since a reflection type photo interrupter is used in the out-of-paper sensor, the sensor may be
affected by light from outside.