Head Current Control - Star Micronics TSP400 Series Technical Manual

CLOCK
SI
LATCH
STROBE1
STROBE2
STROBE3
STROBE4
STROBE5
COMMON

2-2-3. Head current control

Heat buildup in the head during operation can cause print quality to degrade. To maintain uniform quality, the printer
varies the energizing time (time that STROBE remains LOW) in accordance with the head temperature.
The thermal head's surface temperature is calculated based on the resistance value of an attached thermistor. Energizing
time is reduced at higher temperatures, as indicated in the figure 2-6.
STROBE1, STROBE2, STROBE3
STROBE4, STROBE5,
t
Fig.2-6 Timing Chart
t
600
500
400
300
10 20 30
Thermistor Temp. ( C)
Fig. 2-7 Head Energizing Control
– 25 –
THEORY OF OPERATION
24V
t
40 50