Seiko Instruments Inc.
1
Rev.1.0
64-BIT THERMAL PRINTHEAD DRIVER WITH HEAT HISTORY-
BASED PRINTHEAD MANAGEMENT AND 2-BIT PARALLEL INPUT
S-4680A
The S-4680A is a CMOS thermal printhead driver containing two 64-bit shift
registers and six latches (3 x 2). Two-bit parallel data can be input to the
driver. Since the driver print time can be controlled in accordance with heat
history-based data using the gate pins, this driver is suitable for printheads
that perform heat history-based management. Due to its large driver output
current of 50 mA, the S-4680A is ideal for bar-code printers and high-speed
thermal printers.
Features
Low current consumption: 0.8 mA typ.
Driver output current: 50 mA max.
(f
CLK
=5 MHz, SI1 and SI2: Fixed)
Two 64-bit shift registers and six
Driver output voltage:
30 V max.
latches (3 x 2) are built in.
High speed operation:
8 MHz (cascade connection)
Driver-off function when supply voltage falls
Block Diagram
STBX1
V
SS
STBX2
GATEXA1
LOUT
GATEXA2
RIN
GATEXB1
GATEXB2
GATEXC1
V
DD
GATEXC2
GATEXC3
V
SS
SO1
LIN
SO2
ROUT
LATX
SI2
V
DD
SI1
CLK
V
DD
D-FF
D-FF
LA
LA
LA
LA
D-FF
D-FF
D-FF
D-FF
LA
LA
DO
1
DO
64
DO
2
Gate control
circuit
Gate control
circuit
Gate control
circuit
Figure 1 Block Diagram
64-BIT THERMAL PRINTHEAD DRIVER
S-4680A
Rev 1.0
Seiko Instruments Inc.
2
Operation
(1) Basic operation
The shift registers read the data input to the SI1 and SI2 pins at the rising edge of the CLOCK input.
The latch operates depending on the level of the LATX pin. It reads the data of the shift register when
the LATX pin is low and it holds the data of the shift register when it is high. A total of six data items
(current, preceding and previous,) of SI1 and SI2 is held.
The driver output time can be controlled by combining current, preceding, previous, adjacent right and
left preceding data items input from SI1 with gate pulses input from GATEXA1, GATEXA2,
GATEXB1, and GATEXB2. The driver output time can be controlled by combining the current,
preceding, previous, SI1 adjacent right and left preceding and SI1 previous data items input from SI2
with gate pulses input from GATEXC1, GATEXC2, and GATEXC3.
The latch data is output to the driver when the STBX pin is low. The STBX1 pin controls the driver
output of the data input from SI1. The STBX2 pin controls the driver output of the data input from SI2.
When the supply voltage changes from 0 to 5 V or 5 V to 0, the driver output transistor goes off.
(2) Generation of heat history-based printhead management print pulse
SI1 heat history -based printhead management operation:
The pulses input from STBX1 are controlled in accordance with the preceding data item, adjacent
left preceding data item, adjacent right preceding data item, and previous data item, then they are
changed to the respective print pulses. The print pulses determine the time to turn the output
transistor on, and the on time can control print energy. When driver DOn is printed, driver DOn-1
which is one bit earlier is the adjacent left, and driver DOn+1 which is one bit later is the adjacent
right, the data items preceding each of them are the adjacent left preceding data item and
adjacent right preceding data item.
The heat history-based print pulse is generated as follows.
Input pulse
STBX1
STBX1
Corresponding to the shortened
pulse of adjacent left preceding data
Corresponding to the
shortened pulse of previous
data
Corresponding to the shortened pulse
of adjacent right preceding data
Corresponding to the shortened
pulse of preceding data
Figure 2 Heat History-Based Printhead Management Operation
If there is preceding data when a pulse is input from STBX1 as shown in Figure 2, the print pulse
is reduced by the shortened pulse of the preceding data, allowing for printing with less energy.
Similarly, if there is an adjacent right preceding data item, an adjacent left preceding data item or
a previous data item, the input pulse is reduced, allowing for printing with less energy.
64-BIT THERMAL PRINTHEAD DRIVER
Rev 1.0
S-4680A
Seiko Instruments Inc.
3
A print example is given below.
I.
Heat history-based printhead management print pulse when there is preceding data:
STBX1
Print pulse
After history-based printhead management inside the IC
Corresponding to the shortened pulse
of adjacent left preceding data
Corresponding to the
shortened pulse of previous
data
Corresponding to the shortened pulse
of adjacent right preceding data
Corresponding to the shortened pulse of
preceding data
Print pulse
Input pulse
Figure 3 Print Pulse Heat History Management
Print bit (SI1)
Adjacent left
Adjacent right
Previous data
Preceding data
Current data
SI2 heat history-based printhead management operation:
The pulses input from STBX2 are controlled in accordance with the preceding data item, previous
data item, preceding SI1 data item, and adjacent right/left preceding SI1 data items, and they are
changed to the respective print pulses. The print pulses determine the time to turn the output
transistor on, and the on time can control print energy. When driver DOn is printed, driver DOn-1
which is one bit earlier is the adjacent left, and driver DOn+1 which is one bit later is the adjacent
right, the data items preceding each of them are the adjacent left preceding data item and
adjacent right preceding data item.
A heat history-based printhead management print pulse is generated as follows.
Print pulse
STBX2
STBX2
Corresponding to the shortened pulse of adjacent right/left preceding
SI1 data
Corresponding to the shortened pulse of previous data/previous SI1 data
Corresponding to the shortened pulse of preceding data/preceding SI1 data
Figure 4 Generation of Heat History-Based Printhead Management Pulse
If there is preceding data when a pulse is input from STBX2 as shown in Figure 4, the print pulse
is reduced by the shortened pulse of the preceding data, allowing for printing with less print
energy. Similarly, if there is a previous data item, preceding SI1 data item, previous SI1 data, and
adjacent right/left preceding SI1 data item, the input pulse is reduced, allowing for printing with
less print energy.
*
: Data is present
: No data
64-BIT THERMAL PRINTHEAD DRIVER
S-4680A
Rev 1.0
Seiko Instruments Inc.
4
A print example is given below.
I.
Heat history-based printhead management print pulse when there is a preceding data item:
STBX2
Print pulse
Input pulse
Print pulse
After heat history-based printhead management
inside the IC
Corresponding to the shortened pulse of adjacent right/left preceding
SI1 data
Corresponding to the shortened pulse of previous data/previous SI1 data
Corresponding to the shortened pulse of preceding data/preceding SI1 data
Figure 5 Heat History-Based Printhead Management Print Pulse
Print
Print bit (SI1)
bit (SI2)
Adjacent left
Adjacent right
Previous data
Preceding data
Current data
II.
Heat history-based printhead management print pulse when there are a preceding data item, a
preceding SI1 data, and an adjacent left preceding SI1 data item:
STBX2
Print pulse
Input pulse
Print pulse
After heat history-based printhead management
inside the IC
Corresponding to the shortened pulse of adjacent right/left preceding
SI1 data
Corresponding to the shortened pulse of previous data/previous SI1 data
Corresponding to the shortened pulse of preceding data/preceding SI1 data
Figure 6 Heat History-Based Printhead Management Print Pulse
Print
Print bit (SI1)
bit (SI2)
Adjacent left
Adjacent right
Previous data
Preceding data
Current data
*
: Data is present
: No data
*
: Data is present
: No data
64-BIT THERMAL PRINTHEAD DRIVER
Rev 1.0
S-4680A
Seiko Instruments Inc.
5
SI1/SI2 Heat History-Based Printhead Management Print Pulse
The SI1 print pulses are controlled by input pulse at STBX1 and the following signals a, b, c, and
d.
a: Corresponding to the shortened pulse of preceding data:
Pulse width input from GATEXA1
b: Corresponding to the shortened pulse of adjacent left preceding data:
Difference between the pulse width input from GATEXA2 and pulse width input
from GATEXA1
c: Corresponding to the shortened pulse of previous data:
Pulse width input from GATEXB1
d: Corresponding to the shortened pulse of adjacent right preceding data:
Difference between the pulse width input from GATEXB2 and pulse width input
from GATEXB1
STBX1
Corresponding to the shortened pulse of
adjacent left preceding data
Corresponding to the shortened pulse of
adjacent right preceding data
Corresponding to the shortened
pulse of previous data
Corresponding to the shortened pulse of
preceding data
GATEXA1
Corresponding to the shortened pulse of
preceding data
GATEXA2
Corresponding to the shortened pulse of
adjacent left preceding data
GATEXB1
Corresponding to the shortened pulse
of adjacent right preceding data
GATEXB2
Corresponding to the shortened
pulse of previous data
Figure 7 SI1 Heat History-Based Printhead Management Print Pulse
d
c
b
a
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