3-17
3.4 THERMAL HEAD
The thermal head consists of heat elements and a thermal head driver that drives and controls the heat
elements.
The data from the DI terminal is transferred to the shift register at the rising edge of the CLK signal.
The data is stored into the latch register by making
LAT
signal "Low" after one line data is transferred. The
heat elements are activated by making DST signal "High" in accordance with the stored print data.
In the LTPD245D, a division printing by 6 blocks is available. Each block has 64 dots heat elements.
In the LTPD345D at 7.9V or lower, a division printing by 64 dots in 1 block and 128 dots in 4 blocks each are
available. The divided printing is effective for a high print ratio printing because the peak current can be cut
down with the reduction of the average print speed.
3.4.1 Structure of the Thermal Head
The following describes the thermal head block diagram as an example of the LTPD245D.
Figure 3-8 shows the thermal head block diagram when driving the LTPD245D.
Table 3-8 and Table 3-9 show the relationship between DST blocks and activated heating elements.
D I
C L K
L A T
D ST 6
D ST 5
D ST 2
DST 1
V
d d
G ND
V
P
Shift Register
LAT Register
Output Driver
Heating Element
D
O
T
3 8 4
D
O
T
3 2 1
D
O
T
3 2 0
D
O
T
2 5 7
D
O
T
2 5 6
D
O
T
1 2 9
D
O
T
1 2 8
D
O
T
6 5
D
O
T
6 4
D
O
T
1
Block6
Block5
Blcok2
Block1
TH
Thermistor
TH
Figure 3-8 Thermal Head Block Diagram (LTPD245D)
