Note: Descriptions are shown in the official language in which they were submitted.
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INK JET SYSTEM WITH SERIAL DATA PRINTHEADS
Background of the Invention
This invention relates to ink jet printing
systems, and in particular, such systems which employ a
controller for controlling multiple printheads which are
spaced for printing on moving surfaces such as on cartons or
boxes being fed forward by a conveyor.
Ink jet printing systems include a plurality of
ink jet printheads, each having a matrix of ink jets. Each
ink jet has a nozzle constituting a valve seat at its outlet
end, the seat having an orifice for injection of drops of
ink. A solenoid actuated valve member engages and
disengages from the seat to close and open the orifice. A
controller for each printhead including a microprocessor,
processes data for actuating the solenoids to print messages
and to store data. In the past, such controllers
communicated with each printhead via a separate cable for
each printhead which directly connected the controller to
each printhead. In addition, such controllers employed a
ASCII data format in which parallel data was provided to
each of the printheads. This required a large amount of
cabling and required each printhead to print a separate line
of text information. There is a need for an ink jet
printing system which reduces the amount of cabling between
the controller and the printheads and which communicates
with the printheads via a serial data format. There is also
a need for the ability for such a system to allow one
printhead to print more than one line of text or to
configure the system such that a text line can span across
more than one printhead.
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Summary of the Invention
In one aspect of the invention, there is provided a
system for ink jet printing of messages on articles being fed
forward one after another in a path, said system comprising: a
terminal including a keyboard for entering message data
representative of the messages; a controller interconnected
with the terminal for processing the message data received
from the terminal and storing the message data for the
messages, said controller having a serial output port for
providing serial output data representative of the messages;
first and second serially connected ink jet printheads
positioned adjacent said path to serially print the messages
on the articles in response to the serial output data; first
interconnecting means including a first cable connecting the
serial output port of the controller to the first printhead
for providing the serial output data to the first printhead;
second interconnecting means including a second cable
connecting the first printhead to the second printhead for
providing to the second printhead via the serial output port
and the first cable at least some of the serial output data
provided to the first printhead such that no cable directly
connects the controller to the second printhead; and means for
supplying ink to the ink jet printheads.
In a second aspect, there is provided a system for
ink jet printing of messages on articles being fed forward one
after another in a predetermined path, said system comprising:
a terminal including a keyboard for entering message data
representative of the messages; a bit map memory; a controller
interconnected with the terminal for processing the message
data received from the terminal and storing the message data
for the messages in the bit map memory, said controller having
a output port for providing serial output data in a bit map
format representative of the messages; first and second ink
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jet printheads positioned adjacent said path to print the
messages on the articles in response to the serial output
data, first interconnecting means connecting the serial output
port of the controller to the first printhead for providing to
the first printhead a respective portion of the serial output
data in the bit map format to be printed; second
interconnecting means connecting the serial output port of the
controller to the second printhead for providing to the second
printhead a respective portion of the output data in the bit
map format to be printed, said serial output data being
provided to the second printhead via the first printhead and
the second interconnecting means such that no serial output
data is directly provided from the controller to the second
printhead: and means for supplying ink to the ink jet
printheads.
In a third aspect, there is provided an ink jet
printhead controller providing serial output data for a system
for ink jet printing of one message, said system having a
terminal including a keyboard for entering ASCII message data
representative of the message and a plurality of printheads
responsive to the serial output data to print the message on
one article, said controller comprising: a bit map memory; a
processing circuit interconnected with the terminal for
converting the ASCII message data received from the terminal
into a bit map format and storing the converted bit map format
message data in the bit map memory, said processing circuit
having a serial output port for providing serial output data
in a bit map format representative of the one message; and
interconnecting means connecting the serial output port of the
processing circuit to each of the printheads for providing to
each printhead a respective portion of the serial output data
in the bit map format to be printed whereby the plurality of
printheads each receive and print on the one article their
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respective portion of the one message so that the one message
printed on the one article by the plurality of printheads.
In a fourth aspect, there is provided an ink jet
printhead for use with a system for ink jet printing of
messages, said system having a terminal including a keyboard
for entering message data representative of the messages, a
controller interconnected with the terminal for processing the
message data received from the terminal and storing the
message data for the messages in a memory, said controller
having a serial output port for providing serial output data
in a bit map format representative of the messages, said ink
jet printhead comprising: a serial input port adapted for
connection to the serial output port of the controller, a
driver circuit connected to the serial input port and
responsive to a respective portion of the serial output data
provided to the serial input port, a serial output port
connected to the serial input port and adapted to provide to a
serial input port of another printhead a respective portion of
the serial output data provided to the serial input port, a
plurality of ink jets arranged in a matrix and adapted for
ejection of drops of ink across a gap to a surface of the
articles travelling by the printhead to print dots on said
surface in patterns selected from characters for said
messages, and a plurality of electrically actuated valve
means, one for each jet, connected to the driver circuit, each
valve means adapted for electrical operation in response to
the serial output data provided to the driver circuit for
ejecting a drop of ink from its respective ink jet.
In a fifth aspect, there is provided a system for
printing of messages on articles being fed forward one after
another in a predetermined path, said system comprising: an
input for entering message data representative of the
messages; a controller interconnected with the terminal for
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processing the message data received from the terminal and
storing the message data for the messages, said controller
having a output port for providing output data representative
of the messages; first and second serially connected
printheads positioned adjacent said path to print the messages
on the articles in response to the output data: an
interconnect connecting the output port of the controller to
the first printhead for providing the output data to the first
printhead and connecting the first printhead to the second
printhead for providing to the second printhead at least some
of the output data provided to the first printhead: and an ink
supply line for supplying ink to the printheads.
In a sixth aspect, there is provided a system for
printing of messages on articles being fed forward one after
another in predetermined path, said system comprising: an
input for entering message data representative of the
messages; a controller interconnected with the terminal for
processing the message data received from the terminal and
storing the message data for the messages, said controller
having a output port for providing output data representative
of the messages: first and second serially connected
printheads positioned adjacent said path to print the messages
on the articles in response to the output data: an
interconnect connecting the output port of the controller to
the first printhead for providing the output data to the first
printhead and connecting the output port to the second
printhead for providing to the output data to the second
printhead; and an ink supply line for supplying ink to the
first printhead and for supplying ink from the first printhead
to the second printhead whereby ink for the second printhead
is supplied via the first printhead.
It is an object of this invention to provide an
ink jet printer system which is low cost and flexible.
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It is another--object of this invention to provide an ink
jet printer system which employs only a single cable
between the controller and the printheads so that the '
printheada may be serially connected. It is another
object of this invention to provide an ink jet printer '
system which distributes power ae well as data in a
serial manner reducing the number of power cables which
are necessary. It is another object of this invention to
provide an ink jet printer system which employs -
printheads that can print more than one text line at a
time or which allows a text line to span across more than
one printhead without employing custom fonts. It is
another object of this invention to provide an ink jet
printer system having a controller which provides data in
a bit map format to its printheads. -
In one form, the invention comprises a system
for ink jet printing of-messages on articles being fed
forward one after another in a predetermined path. A
terminal including a keyboard is used for entering -
message data representative of- the messages. A
controller interconnected with the terminal processes the
'
message data received from the terminal and stores-the
message data for the messages. The controller has an
output port for providing output data representative of..
the messages. First and-second serially connected ink
jet printheads are positioned adjacent the path to print
the messages on the articles in response to the output -
data. A first interconnecting cable connects the output
port of the controller to the first printhead for-
providing the output data to the first printhead. .A
second interconnecting cable connects the first pririthead
to the second printhead for providing to the second '
printhead at-least some of-the output data provided to
the first printhead_ '
Other objects and features will be in part
apparent and in part pointed out hereinafter.
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Brief Descri~tioa of the Drawiaas
Figure I is a schematic diagram illustrating
' the ink jet system with serial data printheads according
to the invention.
Figure 2 is a block diagram illustrating the
controller of Figure 1 according to the invention.
Figure 3 is block diagram illustrating one of
the printheads of Figure I according to the invention for
use with the controller of Figure 2.
Corresponding reference characters indicate
corresponding parts throughout the drawings.
Detailed Deacriptioa of the Preferred Embodiments
Figure 1 illustrates an ink jet system 100 with
serially connected printheads 102 according to the
invention. The conventional aspects of the system 100
are disclosed in the prior art, such as U.S. Patent Nos.
4,723,131, 4,792,817, and 4,924,241, each of these
patents being incorporated herein in their entirety by
reference. The purpose of ink jet system 100 is to print
messages on articles such as boxes 104 being fed forward
one after another in a predetermined path such as by a
conveyor 106.
System 100 includes a controller 108 for
controlling the operation of the system and particularly
for controlling printheads 102. Initially, the location
or position of each box is detected by a photocell-110
which precedes by a known offset 112 the last printhead
102C. Photocell I10 is connected to controller 108 to
provide such location or position information. In
' 30 addition, a speed encoder 114 is associated with the
conveyor 106 to indicate to controller I08 the speed at
' which the conveyor is travelling. As a result,
controller 108 knows the position of each box 104 on
conveyor 106 at any point in tine.
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Controller 108 controls the printheada 102 in
order to print specific messages on each of the boxes
104. The message may be the same on each box or it may '
be specific to the particular box. For example,
controller 108 may be connected to a scale (not shown)
for weighing each box and-controller 1D8 would control
printheads 102 to print the weight of each box on the box
104. Alternatively, controller 108 may be connected to a
bar code scanner (not shown) which reads the bar code on
each box 104 and prints information relating thereto,
such as aerial number or manufacturing date. The
messages which-are to be printed result from instructions
provided to the controller 108 by some type-of input
device such as an LC100 hand-held terminal 116 or a
personal computer 118 having a keyboard for permitting an
operator to enter messages. Computer 118 may be
networked to the controller_108 via a local area network
(LAN) line 120 such as an ARCNETby Datapoint
Corporation which interconnects LAN terminal boards 122
and 124 respectively located in the computer and the
controller.
Furthermore, controller 1D8 may have one or
more slots f-or receiving memory cards 126 for expanding
the memory of controller 108 or for providing
predetermined information-to-controller-108.
Each printhead 102 requires both a signal line
128 and a power line 130 for providing both data and
power to each printhead 102 for controlling the
printhead. Preferably, the printheads are serially
connected as illustrated in Figure 1. This connection is
sometimes referred to as a "daisy chain" connection in
that signal line 128 is connected to only the first '
printhead 102A. A separate-signsl Line 128AB
interconnects-printheads 102A and 102B and another '
separate signal line 128BC interconnects printheads 102B
and 102C. As a result, signal line 128 is connected only
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to the first printhead 102A and is not connected directly,
but is connected indirectly as will be described below, to
printheads 102B and 102C. Similarly, power line 130 is
connected only to the first printhead 102A. A separate
5 power line 130AB interconnects printheads 102A and 102B to
provide power to printhead 102B. Additionally, a separate
power line 130BC is connected between printheads 102B and
102C to provide power to printhead 102C.
Power line 130 receives its power from power
supply 132. In general, power supply 132 may be also used
to energize a pump 134 which supplies pressurized ink from a
reservoir 136 through an accumulator 138 to an ink supply
line 140 which is connected to each of the printheads 102.
A quick disconnect 142 may be provided in line with each of
the printheads 102 to allow the printhead 102 to be quickly
separated from the ink supply. In addition, an ink
regulator 144 may be placed in series with the pressurized
ink line 140 connected to each printhead 102 to regulate the
volume or pressure of ink being applied to each printhead by
accumulator 138. An example of such an ink delivery system
with accumulator is disclosed in U.S. Patent No. 5,767,883.
In general, controller 108 and power supply 132
are remotely located from the printheads 102. In some
cases, the remote location may be several hundred meters
from the location of the printheads 102. Therefore, the
invention provides a significant advantage over the prior
art in that a single signal line 128 is used to interconnect
the controller 108 and the first printhead 102A and a single
power line 130 is used to interconnect the power supply 132
and the first printhead 102A. Signal lines 128AB and 128AC
are relatively short since the printheads are located
contiguous to each other.
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Similarly, powerlines 130AB and i30BC are also short
because of the close location of all the printheads. in
contrast, the prior art generally-suggests that a '
separate signal line interconnecting each printhead with
the controllerand the power supply resulting in a
significant amount of cabling being necessary to
interconnect these devices.
Although Figure l is illustrated with only
three-printheads 102A, 1028 and 102C, it is contemplated
that the invention may have any number of serially
connected printheads, such as 24 printheads in series.
In general, controller 108 provides serial data to the
first printhead 102A which is clocked through the
printhead and continues via signal line 128AB to the
second printhead 102B and continues via signal line 128AC
to the third printhead 102C. For example, suppose
printhead i02A will be printing a character "X,"
printhead 102B will be printing a character !'Y," and
printhead 102C will be printing a character-"Z" so that
the combined printheads would be printing "XYZ."
Controller 108 would provide the serial data such that
character Z would be clocked into printhead 102A. Next,
controller 108 would clock character Y into printhead
102A causing character Z which had been previously
clocked into printhead 102A to be clocked into printhead
102B. Finally, controller 108 would clock character X
into printhead 102A causing character Y to be clocked
into printhead 102B and, in turn, causing character Z to
be clocked into-printhead 102C. Each printhead would
then have the appropriate data for executing the print
operation.
Accordingly, system 100 constitutes a system '
for ink-jet printing of- messages on articles such as
boxes 104 being fed forward one after another along a
predetermined path--suchas the path defined by conveyor
106. System 100 includes--terminal 116 and/or personal
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computer 118, either of which constitutes a terminal
including a keyboard for entering message data
' representative of the messages. Controller 108
constitutes a controller interconnected with the terminal
' 5 for processing the message data received from the
terminal and storing the message data for the messages.
Controller 108 has an output port to which signal line
128 is connected for providing output data representative
of the messages. Printheada 102A and 102B constitute
first and second serially connected ink jet printheads
positioned adjacent the path defined by conveyor 106 to
print the messages on the boxes 104 in response to the
output data. Signal line 128 constitutes first
interconnecting means connecting the output port of the
controller 108 to the first printhead 102A for providing
the output data to the first printhead. Signal line
128AB constitutes second interconnecting means connecting
the first printhead 102A to the second printhead 102B for
providing to the second printhead at least some of the
output data provided to the first printhead. Reservoir-
134, pump 136, and accumulator 138 constitute means for
supplying ink to the jets of the printheads 102.
Figure 2 illustrates in block diagram form one
preferred embodiment of the controller 108. Controller
108 is built around a central processing unit 200 such a
Motorola 68332 microprocessor.- CPU 200 receives various
information as generally indicated above with regard to
Figure 1.- Inparticular, a terminal with keyboard 116
may be connected to CPU 100 to define the messages.
Alternatively, or in addition, CPU 200 may be part of a
network including an LAN interface board 124
communicating with the CPU 200 either directly or via a
bidirectional parallel port (not shown). Controller 108
' also includes an encoder interface 204 for communicating
with and receiving signals from the speed encoder 114
which monitors the velocity of conveyor 106.
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Additionally, controller 1D8 includes a photocell
interface 206-which communicates with and receives
signals from photocell 110 to monitor the position--of the
boxes 104 as they enter the print area.
Information provided to CPU 200 ie stored in a '
CPU memory 208 such as a random access memory which
stores information in a ASCII format.- Additionally, a
buffer 210 may be provided to accommodate the additional
memory cards 126 which may be added to controller 108.
In order to convert the ASCII format
information stored in CPU memory 208, controller 108 also
includes a graphics co-processor 220 such as an-RPX chip
manufactured by Cirrus Logic (CL-GP4150-Raster Printer
Accelerator). CPU 200 feeds the information in CPU
memory 208 via line 222 to co-processor 220, which-
converts the ASCII format information stored within CPU
memory 208 into a bit map form. This bit map information
is stored by co-processor 220 in a dynamic random access
memory 224. CPU 200 controls a timer circuit 230 which
in turn controls a flip-flop circuit 232 which generates
a clock signal via line 234. Co-processor 220 may also
be associated with a reference oscillator 222. Timer 230
also generates a latch signal-synchronized with the clock
signal, the latch signal being provided via line 236.
The clock signal via line 234 is used by co-processor 220
to clock the bit map data out of DRAM 224 and to provide
such data via-data line 238. A serial transmitter such
as an RS-422 chip (SN75ALS197) manufactured by Texas
Instruments is connected to data line 238 as well as
being connected to clock line 234 and latch line 236 to
transmit the data, clock, and latch signals-to the first
printhead 102A via signal line 128. The text and -
graphics to be printed by the printheads 102 is bit
mapped inmemory 224 and shifted out serially by the co- '
processor 220. The printheads 102 are treated as if they
are or_e combined printheadstacked one on the other,
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although they can be vertically spaced from one another.
The serial bits provided via signal line 128 are shifted
' through each printhead and onto the next printhead. The
number of times that the serial bits are shifted is the
sum of all the orifices in the printhead chain so that
when the shifting stops, each printhead has the proper
bits for that printhead. As a result, printheads having
different numbers of ink jets or different orifices may
be combined together. A text line can span across more
than one printhead and one printhead can print more than
one text line. In addition, text can be rotated or
inverted. Thia is in contrast to the prior art where a
custom font was needed if each printhead was not limited
to only one text line. According to the invention, any
size and number of printheads can be connected to the
controller unit and daisy chained together, such as a
seven dot head, a nine dot head, an eighteen dot head, a
twenty-four dot head, or a thirty-two dot head, or any
other size.
Figure 3 illustrates in block diagram form one
preferred embodiment of the printhead 102. Preferably,
each printhead has the same configuration so that the
printheads are interchangeable. Each printhead 102
includes a aerial receiver 300 which is connected to a
signal line connected to a previous printhead or to
controller 108. For example, the serial receiver (300)
of printhead 102A is connected to the serial transmitter
240 of controller 108 via signal line 128. The serial
receiver (300) of printhead 102B is connected to the
serial transmitter (316) of printhead 102A via signal
line 128AB. Similarly, the aerial receiver (300) of
Y
printhead 102C is connected to the serial transmitter
(316) of printhead 102B via signal line 128BC. As a
result of these connections, each serial receiver 300
receives a data signal which is provided via a data line
302, a clock signal which is provided via a clock line
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304 and a-latch signal which is provided via a latch line
306. Printhead 102 includes an array of aerial to
parallel-registers 308 which are serially connected. The '
number of registers depends on the number of ink jets of
5 the printhead. In the embodiment illustrated in Figure '
3, an eighteen-ink jet printhead is shown. Therefore,
two registers-308, each having nine outputs, are
employed. Initially, register-30BA receives the data via
line 302 and converts the serial data to parallel-
10 information for-selectively energizing nine drivers 310A.
Drivers 310A selectively actuate nine solenoids 312 to
drive nine ink jets 314 which are arranged in a matrix
and supplied with ink via pressurized ink supply line 140
connected to accumulator-138. The solenoids 3i2 and
their respective controlled ink jets 314 constitute a
plurality of electrically actuated valve means, one for
each--jet, adapted for electrical operation in response to
the data bits for ejecting a drop of ink from its
respective nozzle.
Register 308A also receives both clock and
latch signals via clock line 304 and latch line 306,
respectively, so that data can be clocked through
register 3DSA and provided-at its data-out line to the -
next serial to parallel register 308B. Once again,
register 3D8B converts the-serial data to parallel
signals which are latched to energize nine drivers 310B
for actuating nine solenoids 312B which control nine ink
jets 314B. The data out line ofregister 308B is-then
connected to a serial transmitter 316 which is also
connected to the clock line 304 and they latch line 306.
Transmitter 316 transmits the data, clock, and latch
signals along with a 15 volt do signal provided from the
power supply 132 and used to drive the solenoids 312, to
the next printhead in the daisy chain aeries. Printhead
102 also includes a voltage regulator 318 which reduces
and controls-the 15 volt do power line to provide a 5
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volt logic signal which is employed by the components of
printhead 302 such ae receiver 300, and registers 308.
Printhead,102 also includes a timer 320 responsive to the
latch signal provided by latch line 306 to generate an
' S enable signal which enables the registers 308. Timer 320
is variable and determines size of the dots printed by
the ink jets as the jets eject drops of ink onto the
surface of the box. As a result, the dots are in
patterns selected from characters for the messages being
printed.
In general, printhead 102 of Figure 3 operates
as follows. Each serial receiver 300 and serial
transmitter 316 has a data line 302, a clock line 304,
and a latch line 306. The aerial print data bit stream
is clocked synchronously into the first register 308A and
back out through to the next register 308B and finally to
the next printhead via transmitter 316. When controller
108 has completed clocking out all of the print data, it
sends a latch pulse via the latch line 306. The print
- data is then latched into the registers 308 in the
printheads with the rising edge of the latch pulse. The
trailing edge of the latch pulse triggers timer 320 which
enables the parallel output of the- registers 308 and
allows print data to go to the solenoid drivers 310. A
- logic one turns on a solenoid driver to actuate its
solenoid 312 and a logic zero does not. When a solenoid
312 is energized, a valve is opened and ink, under
pressure as provided via ink supply line 140, passes
through an orifice-. The adjustable timer 320 sets the
size of the dots by the amount of time that the ink valve
stays open.
More particularly, the printhead operation is
as follows. Receiver 300 converts differential signals
which are provided via the signal line 128 to standard
logic signal levels. The differential signals consist of
two inputs for each signal line . When one of the signal
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line inputs goes to 5 volts, the other input goes to 0.
A resistor (not shown) ie connected across each -_
differential pair to match the characteristic impedance
of the cable 128. Data line 302, clock line 304, and
latch line 306 are logic level signal outputs which may '
be pulled-up to 5 volts in order to interface these TTL
outputs to the CMOS inputs of the registers 308. The
data is shifted one bit-with-each clock pulse and shifted
out the data out port of register 308A to the data in
port of register 308B. In the same way, data is shifted
out of register 308B via its data out port to the serial
transmitter-316.
When the controller 108 is finished shifting
out the data to all the printheads, it sends the latch
pulse via latch line 306 which is a positive going pulse.
The rising edge of the latch pulse latches the data into
the registers 308 of each-printhead. The pulse width of
the latch signal allows time for the propagation delay.
The falling edge of the latch pulse triggers timer-chip
320 which is a 74HC221 manufactured by Texas Instruments.
When timer 320 is triggered, it provides an enable-output
which goes low for a time period preset by a resistor
capacitor (RC) combination (not shown) which has a-range
between 6D and 45D_microaeconds. The enable output of
timer 320 is connected to the enable ports of the-
registers 308. Each register 308 has 9 parallel output
pins, totalling 18, which control the 18-solenoid driver
circuits. A low signal to the output enable pins of the
registers 308 causes the data in the registers to be
connected to their output pins and a logic one enables
the solenoid -driver .circuits 310 or a logic zero disables
the driver.circuita 310. After the timer 320 times out,
the output enable pins of the registers 308 are brought
high and the outputs go into a high impedance state so
that-the solenoid driver circuits 31D-are disabled by a
pull-down resistor (not shown).
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One significant advantage of the circuit of
printhead 102 over the prior art is that is minimizes the
amount of cabling from the controller 108 to a group of
printheada. For example, 24 printheads would require 24
cables connected to controller 108, on going to each
printhead. Since controller 108 is remote from the
printheads and sometimes several hundred feet from the
printheada, this requires a significant amount of
cabling. In contrast, the circuit of printhead 102
requires only one cable which connects controller 108 to
the first printhead 102A and then cables 128AB and 128BC
connect the first printhead 128A to the second printhead
128B and the second printhead 128B to the third printhead
128C_ This also reduces the amount of circuitry required
in the controller 108 and reduces the number of wires in
the cable. A twenty-four dot printhead would normally
require a cable of 25 wires or more. The invention
reduces the cable connected to the controller 108 to only
the six wires needed for carrying the differential data
clock and latch signals.
In view of the above, it will be seen that the
several objects of-the invention are achieved and other
advantageous results attained.-
Aa various changes could be made in the above
products without departing from the scope of the
invention, it is intended that all matter contained in
the above description and shown in the accompanying
drawings shall be interpreted as illustrative and not in
a limiting sense.
