Print Head Circuit - Toshiba B-SV4T SERIES Manual

2.7 Print Head Circuit

Fig. 9 Print Head Circuit Diagram
CLK and LAT connect to thermal head control clock and data latch respectively.
TPH_EN signal controls the DC24V voltage of the thermal head. When TPH_EN is
high, the thermal head will be separated from 24V (V ). U21 controls protecting print
DD
head. It is used to make sure the power of print head is off when switch off the printer.
Q1 and Q2 are used to limit current of print head.
Both /STB1 and /STB2 determine whether to heat the thermal head or not. The RC
charging time of U15 and 74HC123 limit the heating time of print head to avoid burning
the print head.
DI signal sends printer data to the print head.
TM signal is the temperature/voltage sensor for thermal head.
The Vdet feeds back the voltage and compensates the heat time for voltage accuracy
when printing.
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