Note: Descriptions are shown in the official language in which they were submitted.
~ 202:~5~
BACKGROUND OF THE INVENTION
The present invention relates to offset printing presses
and, particularly, to the eIectronic control of such presses.
Web offset printing presses have gained widespread
acceptance by metropolitan daily as well as weekly newspapers.
Such presses produce a quality black and white or color
product at very high speeds. To maintain image quality, a
number of printing functions must be controlled very precisely
as the press is operating. These include the control of press
speed, the control of color register, the control of ink flow
and the control of dampening water.
In all printing processes there must be some way to
separate the image area from the non-image area. This is done
in letterpress printing by raising the image area above the
non-image area and is termed "relief printing". The ink
roller only touches the high part of the plate, which in turn,
touches the paper to transfer the ink. In offset lithography,
however, the ~eparation is achieved chemically. The
lithographic plate has a flat surface and the image area is
made grease-receptive so that it will accept ink, and the non-
image area is made water-receptive so it will repel ink when
wet.
2022~59
In a web offset printing press the lithographic plate is
mounted to a rotating plate cylinder. The ink is injected
onto an ink pickup roller and from there it is conveyed
through a series of transfer rollers which spread the ink
uniformly along their length and transfer the ink to the image
areas of the rotating plate. Similarly, dampening water is
applied to a fountain roller and is conveyed through one or
more transfer rollers to the non-image areas of the rotating
plate cylinder. The plate cylinder rotates in contact with
a blanket cylinder which transfers the ink image from the
plate cylinder to the moving paper web.
It is readily apparent that the amount of ink and
dampening water supplied to the plate cylinder is directly
proportional to the press speed. At higher press speeds the
plate cylinder and blanket cylinder transfer ink and water to
the paper web at a higher rate, and the inking and dampening
systems must, therefore, supply more ink and water. It is
also well known that this relationship is not linear and that
the rate at which ink and dampening water is applied follows
a complex rate curve which is unique to each press and may be
unique to each run on a press. Not so apparent is the fact
that the ink and water may be applied non-uniformly across the
width of the ink pickup roller and the fountain roller in
2022~9
order to achieve uniform printing guality along the width of
the web. If this is not done, there may be significant
changes in the guality of the printed images across the width
of the moving web.
Prior press control systems have provided limited control
over the rate at which dampening water and ink has been
applied as a function of press speed. For example, in the
case of damping wat.er, these systems pulse the nozzles on the
spray bar on and off at one of a plurality of selectable pulse
rates. The particular pulse rate selected is determined by
the press speed. The particular pulse rates and selection
points between pulse rates is preset to follow the dampening
rate curve of the press as closely as possible. There is no
means for easily changing these values or for providing a
continuous range of pulse rates which closely follow the rate
curve. In addition, whi~e the amount of dampening water
applied by the spray bar can be adjusted over the width
thereof, this is a manual adjustment which may only be made
locally at a spray bar controller. Thus, if inconsistencies
in print guality are observed over the width of the image,
manual adjustments to the circuitry must be made at a local
control panel.
2û2~05~
SUMMARY OF THE INVENTION
The present invention relates to a control method
for an offset printing press and, particularly, to
providing ink zero calibration for the printing press.
In a first ~ nt, the invention comprises a
method of providing a software zero state for a plurality
of ink adjusting modules in at least one page pack of a
printing couple in a printing press, each of the ink
adjusting modules being provided for adjusting an
associated plunger assembly for dispensing ink to an ink
rail in the printing press, each ink adjusting module
having an ink control level which contacts the plunger
assembly to change the ink volume being pumped by the
associated plunger assembly to the ink rail, having a
mechanical stop for the ink control lever and having an
adjustable ink control lever and having an adjustable ink
control rod contacting the ink control lever, the method
comprising the steps of: placing the printing couple in a
zero mode; positioning an ink control stopscrew of each ink
page pack at the associated mechanical stop; operating a
bidirectional motor in each ink adjustable module to move
the ink control lever to a position corr-ospsn~l;nlJ to a
desired printing via the ink module control rod which is
connected to the motor and which contacts the control
lever; and measuring the position of the motor with a
potentiometer; storing the position of each motor, from a
position value output by the associated potentiometer, in
-- 5 --
~n7~ns~
a memory thereby providing the software zeroes for the
printing press.
In a second r-' QAir- t, a method of providing a
software zero state for a plurality of ink adjusting
s modules in a printing press, each of the ink adjusting
modules being provided for adjusting an associated plunger
assembly for dispensing ink to an ink rail in the printing
press, each ink adjusting module having an ink control
lever which contacts the plunger assembly to change the ink
lo volume being pumped by the associated plunger assembly to
the ink rail, having a mechanical stop for the ink control
lever and having an adjustable ink control rod contacting
the ink control lever, the method comprising the steps of:
placing the printing press in a manual mode; positioning
15 the ink control lever of each ink adjustment module at the
associated mechanical stop; operating a bidirectional motor
in each ink adjustment module to move the ink control lever
to a position corresponding to a desired black printing via
the ink module control rod which is connected to the motor
20 and which contacts the control lever; measuring the
position of the motor with a potentiometer; and storing the
position of each motor, from a position value output by the
associated potentiometer, in a memory as a function of
paper type, ink type and damping solution used in the
25 printing press thereby storing a plurality of sets of
software zeroes for different paper types, ink types and
damping solutions.
In a third embodiment, a method of providing a
software zero state for a plurality of ink adjusting
-- 6 --
n 5 ~
modules in a printing press, each of the ink adjusting
modules being provided for adjusting an associated plunger
assembly for dispensing ink to an ink rail in the printing
press, each ink adjusting module having an ink control
5 lever which contacts the plunger assembly to change the ink
volume being pumped by the associated plunger assembly to
the ink rail, having a mechanical stop for the ink control
lever and having an adjustable ink control rod contacting
the ink control lever, the method comprising the steps of:
10 placing the printing press in a manual mode; positioning
the ink control lever of each ink adjustment module at the
associated mechanical stop; operating a bidirectional motor
in each ink adjustment module to move the ink control lever
to a position CUL~ r1;nq to a desired black printing via
15 the ink module control rod which is connected to the motor
and which contacts the control lever; measuring the
position of the motor with a potentiometer; storing the
position of each motor from a position value output by the
potentiometer in a memory as a function of paper type, ink
20 type and damping solution used in the printing press, and
storing a plurality of sets of software zeroes for
different paper types, ink types and damping solutions;
placing the printing press in an automatic mode; retrieving
the software zeroes from the memory for the paper type, ink
25 type and damping solution being used in a printing press;
and positioning each of the motors according to their
respective software zero before operating the printing
press .
- 6a -
~n ~ ~Q 5 ~
The software zeroes can be stored in buffers in
each associated coupling of the printing press, the
printing press having at least one couple and the memory
being the buffers.
S Alternatively the method can store the software
zeroes in a memory in the printing press, the printing
press having at least one couple and the memory being the
buf f ers .
Alternatively the method can store the software
lo zeroes in a memory in the printing press or the software
zeroes can be stored in a memory of a master work station
which is connected to the printing press.
When at least the ink type is changed to a new
combination in the printing press, the method further has
the step of providing the printing press with a set of
software zeroes previously stored in the plurality of sets
of software zeroes which cu,, e:,,uond to the new combination
of at least ink type.
- 6b -
- ~ 20220~i9
..
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed
to be novel, are set forth with particularity in the appended
claims. The invention, toget~er with further objects and
advantages, may best be understood by reference to the
following description taken in coniunction with the
accompanying drawings, in the several Figures in which like
reference numerals identify like elements, and in which:
FIG. 1 is a sche~at~c representation of a web offset
printing press and its control system;
FIG. 2 is a schematic representation of two printing
units in the press of FIG. 1:
FIG. 3 is a pictorial view of a dampening water spray bar
which is employed in the printing units of FIG. 2;
FIG. 4 is an electrical block diagram of a unit
controller which forms part of the press control system of
FIG. l;
PI~. 5 is an electrical schematic diagram of a dampener,
register, ink (ndrink") processor which forms part of the unit
controller of FIG. 4;
FIG. 6 is an electrical schematic diagram of a solenoid
interface circuit which forms part of the drink processor of
FIG. S;
' ~ 2022Q59
.
FIG. 7 is an electrical schematic diagram of a speed
interface circuit which forms part of the drink processor of
FIG. 5;
FIG. 8 is a schematic representation of important data
structures which are stored in the RAM of FIG. 5;
FIGS. 9A-9C are ~chematic representations of specific
data structures which are ~hown as blocks in FIG. 8;
FIG. 10 is a diagram of the ink injector system used in
the present invention;
FIG. ll is a perspective view partially cut away of a
portion of the FIG. 10 ink injector system;
FIG. 12 is a graphic representation of a damp rate curve
defined by damp rate curve data stored in the drink processor
of FIG. 5; and
FIG. 13 is a graphic representation of an ink rate curve
defined ~y ink rate curve data stored in the drink processor
of FIG. 5.
20220 59
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring particularly to FIG. 1, a printing press
is comprised of one or more printing units 10 which are
controlled from a master work station 11. Each printing unit
is linked to the master work station by a unit controller 12
which communicates through a local area network 13. As
described in U.S. Patent No. 4,667,323, the master work
station 11 and the unit controllers 12 may send messages to
each other through the network 13 to both control the
operation of the press and to gather production information.
Referring particularly to FIGS. 1 and 2, each
printing unit 10 is comprised of four units which are referred
to as levels A, B, C and D and which are designated herein as
units 10A, 10B, 10C and 10D. The units 10A-D are stacked one
on top of the other and a web 15 passes upward through them
for printing on one or both sides. In the preferred
embodiment shown, the printing units 10 are configured for
full color printing on both sides of the web, where the
separate units 10A-D print the respective colors blue, red,
yellow and black.
As shown in FIG. 2, each unit 10A-D includes two
printing couples comprised of a blanket cylinder 20 and a
plate cylinder 21. The web 15 passes between the blanket
2022Q~9
cylinders 20 in each unit for printing on both sides. Ink is
applied to each plate cylinder 21 by a series of ink transfer
rollers 22 which receive ink from an ink pickup roller 23.
As is well known in the art, the ink transfer rollers 22
insure that the ink is distributed uniformly along their
length and is applied uniformly to the rotating plate cylinder
21. An ink rail 400 applies ink to a distribution ink drum
402 which in turn transfers the ink to the ink pickup roller
23. Similarly, each plate cylinder 21 is supplied with
dampening water by a pair of dampener transfer rollers 24 and
a dampener rider roller 25. A spray bar assembly 26 applies
dampening water to each of the dampener rider rollers 25.
Referring particularly to FIG. 3, each spray bar assembly
26 receives a supply of pressurized water from a water supply
tank 27 through a pump 28 and solenoid valve 29. The spray
bar assembly 26 includes eight nozzles 30 which each produce
a flat, fan-shaped spray pattern of water when an associated
solenoid valve 31 is energized. When all eight solenoid
valves 31 are energized, a thin line of water is sprayed along
the entire length of the associated dampener rider roller 25.
As is well known in the art, the solenoid valves 31 are pulsed
on and off at a rate which is proportional to press speed so
that the proper amount of dampening water is applied and
2022~
transferred to the plate cylinder 21. It is also well known
that means must be provided for separately adjusting the
amount of water sprayed by each nozzle 30 to account for
variations in the distribution of dampening water over the
length of the plate cylinder 21.
The injector i~k system delivers a controlled amount of
ink to the distribution drum 402. Referring now to Figures
lO and 11. Each printing couple has four page packs 404.
The page pack 404 is the part of the injector ink system which
provides ink to one page position. Page pack gearboxes 406
are located along a drive shaft in the arch of the unit. Each
gearbox 406 has a clutch arrangement to engage or silence each
page pack 404.
The page pack 404 provides ink to one page which consists
of eight columns. Each page pack 404 has eight variable
stroXe plungers 408 which pump a preset amount of ink to each
page column. The stroke of each plunger 408 is set by the ink
adjustment modules 410 which are located beneath the page pack
404.
The amount of ink fed to the ink train rollers is
determined by:
1. The length of the plunger stroke at each column.
20220~9
2. The operating speed of the ink motor which operates
the page packs 404 and distribution ink drum 402.
During unit operation, the ink motor is controlled by the
proportional ink circuit in the operator's console. This
circuit will automatically vary ink motor speed with press
speed.
Located below each page pack 404 are a series of ink
adjustment modules 410. There are 8 ink adjustment modules
410 to a page pack 404 for a total of 32 per printing couple.
The ink adjustment module 410 adjusts an ink column by
adjusting the stroke of the page pack plunger 408 which
increases or decreases the volume of ink fed to the ink rail
410. Ink modules 410 are activated by the controls on a Unit
Control Panel, or from the operator's console.
When the ink motor is activated, an ink control rod 414
moves against a spring loaded control lever 416. The control
lever 416 and plunger assembly 408 are connected to a common
shaft. When the control rod 414 moves, it changes the
position of the control lever 416 which changes the length of
the pump stroke, thereby changing the ink volume being pumped
to the ink rail 400. A mechanical stop 418 contacts the
control lever 416 as shown.
~ 2022~59
A bidirectional motor 420 connected to the ink control
rod 414 is provided for establishing a "zero" position of the
ink control rod which corresponds to a desired "black" printing
qual~ty or other quality of a type or color of ink being used.
The position of the bidirectional motor 420 is sensed by
potentiometer 422 which outputs a signal which is stored in a
memory either in the printing press or a master work station.
These stored values are "software zeroes" which are particular
to at least a type of ink used in the printing press. When one
or all of these elements are changed in the printing press, the
previously stored "software zeroes" for this combination is
downloaded to reset the ink ad~ustment modules 410 to the
correct zero ~etting.
The purpose of the ink rail 400 is to supply a
predetermined amount of ink to the distribution ink drum 402.
The ink rail 400 is located in the aisle side of the unit and
extends across the full width of the unit. The rail is hinged
so it can be pivoted for cleaning and maintenance.
Ink from the four page packs 404 is pumped through
connecting hoses 412 to openings in the ink rail body. It
then moves through the slots of the orifice plate which is
located in the center of the ink rail 400. The rail 400 is
contoured and precisely located near the surface of the
distribution ink drum 402.
- !! 2~22059
Referring to FIGS. 1 and 4, the spray bars 26 and ink
rails 410 are operated by the unit controllers 12. Each unit
controller includes a communications processor 30 of the type
disclosed in the above-cited U.S. Patent No. 4,667,323 which
interfaces with the local area network 13. The communications
processor 30 provides six serial communications channels 31
through which it can receive input messages for transmission
on the network 13. Messages which are received through the
network 13 by the communications processor 30 are distributed
to the appropriate serial channel 30. The serial
communications channels 30 employ a standard RS 422 protocol.
Four of the serial channels 30 connect to respective
drink processors 35A, 35B, 35C and 35D. Each drink processor
35 is coupled to sensing devices and operating devices on a
respective one of the levels A-D of the printing unit 10. In
addition to receiving a press speed feedback signal through
a pair of lines 37 and press monitor and control 38 from a
speed sensor 3~ mDunted on the units ~OA, each drinX processor
35A-D ~r~d~ces output signals which control the solenoid
val~es 31 on the spray bars 26 and the page packs 404 for the
ink rail 400. The drink processors 35A-D also control color
register.
14
J 20220~9
Referring particularly to FIG. 5, each drink processor
35 is structured about a 23-bit address bus 40 and a 16-bit
data bus 41 which are controlled by a 16-bit microprocessor
42. The microprocessor 42 is a model 68000 sold commercially
by Motorola, Inc. which is operated by a 10 mHz clock 43. In
response to pro~ram instructions which are stored in a read-
only memory (ROM) 44, the microprocessor 42 addresses elements
of the drink processor 35 through the address bus 40 and
exchanges data with the addressed element through the data
bus 41. The state of a read/write (R/W) control line 45
determines if data is read from the addressed element or is
written to it. Those skilled in the art will recognize that
the addressable elements are integrated circuits which occupy
a considerable address space. They are enabled by a chip
enable circuit 46 when an address within their range is
produced on the address bus 40. The chip enable circuit 46
is comprised of logic gates and three PAL16L8 programmable
logic arrays sold commercially by Advanced Micro Devices, Inc.
As is well known in the art, the chip enable circuit 46 is
responsive to the address on the bus 40 and a control signal
on a line 47 from the microprocessor 42 to produce a chip
select signal for the addressed element. For example, the ROM
44 is enabled through a line 48 when a read cycle is executed
20220~!~
in the address range $Foo000 through SF7FFFF. The address
space oc~upied by each of the addressable elements in the
drink processor 35 is given in Table A.
Table A
ROM 44 SF00000 to SF7FFFF
RAM 50 $000000 to $06FFFF
Programmable Interface
Timer 60 ~300340 to $30037F
Timer 100 ~300360
PCO 300358
PC1 ~300358
Programmable Interface
Controller 70 ~300380 to $3003BF
Timer 85 '3003A0
Port PA ~300390
Port PB ~300392
PC3 ~300398
Programmable Interface
Controller 72 $3003C0 to $3003FF
DUART S5 $200000 to $20003F
Referring still to FIG. 5, whereas the ROM 44 stores the
programs or "firmware" which operates the microprocessor 42
to carry out the functions of the drink processor 35, a
read/write random access memory (RAM) 50 stores the data
structures which are employed to carry out these functions.
As will be described in more detail below, these data
structures include elements which are collectively referred
2022~9
to herein as a switch database 51, a control database 52,
receive message buffers 49, and send message buffers 66. For
example, the switch database 51 indicates the status of
various switches on the local control panels 53, whereas the
control database 52 stores data indicative of press speed,
nozzle pulse rate, and nozzle pulse width and parameters for
the ink injector system. The RAM 50 is enabled for a read or
write cycle with the microprocessor 42 through a control line
54.
The drink processor 35 is coupled to one of the serial
channels 31 of the communications processor 30 by a dual
universal async~ronous receiver/transmitter (DUART) 55. The
DUART 55 is commercially available as an integrated circuit
model 68681 from ~otorola, Inc. It operates to convert
message data written to the DUART 55 by the microprocessor 42
into a serial bit stream which is applied to the serial
channel 31 by a line drive circuit 56 that is compatible with
the RS 42~ standard. Similarly, the DUART 55 will receive a
serial bit stream through a line receiver 57 and convert it
to a message that may be read by the microprocessor 42. The
DUART 55 is driven by a 3.6864 mHz clock produced by a crystal
58 and is enabled for either a read or write cycle through
control line 59.
2~220~
The press speed feedback signal as well as signals from
the local control panel 53 are ir.put to the drink processor
3S through a programmable interface timer (PIT) 60. The PIT
60 is commercially available in integrated circuit form as the
model 68230 from Motorola, I~c~ It provides two 8-bit
parallel ports which can be configured as either inputs or
outputs and a number of separate input and output points. In
the preferred embodiment, one of the ports is used to input
switch signals from the control panel 53 through lines 60, and
the second port is used to output indicator light signals to
the control panel 53 through lines 61. The PIT 60 is enabled
through control line 62 and its internal registers are
selected by leads A0-A4 in the address bus 40.
In addition to the parallel I/0 ports, the PIT 60
includes a programmable timer/counter. This timer may be
started and stopped when written to by the microprocessor 42
and it is incremented at a rate of 312.5 kHz by an internal
clock driven by the 10 mHz clock 43. When the timer is
started, a logic high pulse is also produced at an output 63
to a speed interface circuit 64. When the interface circuit
64 subsequently produces a pulse on input line 65, as will be
described in detail below, the timer stops incrementing and
a flag bit is set in the PIT 60 which indicates the timer has
18
J 2~ g
stopped. This flag bit is periodically read and checked by
the microprocessor 42, and when set, the microprocessor 42
reads the timer value from the PIT 60 and uses it to calculate
current press speed.
Referring still to FIG. 5, the solenoid valves 31 on each
spray bar assembly 26 are operated through a programmable
interface controller (PIC) 70 or 72 and an associated solenoid
interface circuit 71 or 73. The PICs 70 and 72 are
commercially available integrated circuits sold by Motorola,
Inc. as the model 68230. Each includes a pair of 8-bit output
registers as well as a single bit output indicated at 75 and
76. Each output register can be separately addressed and an
8-bit byte of data can be written thereto by the
microprocessor 42. The two 8-bit bytes of output data are
applied to the respective solenoid interface circuits 71 and
73. As will be explained in more detail below, the solenoid
valves 31 are turned on for a short time period each time a
pulse is produced at the single bit output of the PICs 70 and
72. This output pulse is produced each time an internal timer
expires, and the rate at which the timer expires can be set
to a range of values by the microprocessor 42. The time
period which each solenoid valve 31 remains energized is
determined by the operation of the solenoid interface circuits
19
2~322~9
,
71 and 73, which in turn can be separately configured by
writing values to the registers in the PICs 70 and 72. As a
result, the rate at which the spray bars 26 are pulsed on is
under control of the programs executed by the microprocessor
42, and the duration of the spray pulses from each nozzle 30
of the spray bars 26 can be separately controlled. Similarly,
the ink injector system 424 having the page packs 404, the ink
adjustment modules 410 and the ink rail 400 is connected via
interface 426 to the address bus 40 and the data bus 41.
Operation is substantially equivalent to operation of the
spray bars 26.
The solenoid interface circuit 71 is shown in FIG. 6 and
it should be understood that the interface circuits 73 and 426
are virtually identical. Each includes a set of eight 8-bit
binary counters 80 and a set of eight R/S flip-flops 81 ~nd
82. The counters 80 are available in integrated circuit form
as the 74LS592 from Texas Instruments, Inc. and they each
include an internal 8-bit input register. This input register
is loaded wit~ an 8-bit binary number on output bus 83 when
a pulse is applied to an RCK input of the counter 80. The RCK
inputs of the eight counters 80 are connected to respective
ones of the output terminals PB0-PB7 of the PIC 70, and the
eight leads in the output bus 83 are driven by the output
- ~ 20~2(~9
terminals PA0-PA7 of the PIC 70 through a buffer 84. Thus,
any or all of the registers in the counters 80 can be loaded
with a binary number on the PA output port of the PIC 70 by
enabling the counter's RCK input with a "1" on the
corresponding lead of the PB output port. As will be
described in more detail below, this circuitry is used to
separately preset each 8-bit counter 80 so that the time
interval which each of the solenoid valves 30 remains on can
be separately controlled.
Re~erring still to FIG. 6, an output pulse is produced
at the PC3 output pin of the PIC 70 each time an internal
timer 85 expires. The timer 85 is preset with a calculated
current pulse rate value by the microprocessor 42. Each time
the timer 85 expires, two phase displaced pulses are produced
by a ~et of four D-type flip-flops 86-89. The Q output of
flip-flop 87 sets the ~S flip-flops 81 on the leading edge of
one pulse and it presets four of the counters 80 with the
values stored in their respective input registers. On the
trai~ing edge of this first pulse, the Q output of the flip-
flop 87 returns to a logic low which enables the same four
counters to begin counting. The remaining four counters 80
and the R/S flip-flops 82 are operated in the same manner by
the Q and Q outputs of the flip-flop 89. The only difference
- 1 2~2~Q~9
is that the operation of the flip-flop 89 i8 delayed one-half
the time period between successive pulses from the flip-flop
87.
The eight counters 80 are incremented by 2 kHz clock
pulses until they reach the all ones condition. At this point
the output of the counter 80 goes to a logic low voltage and
it resets the R/S flip-flop 81 or 82 to which it connects.
The output of each R/S flip-flop 81 or 82 controls the
operation of one of the solenoid valves 31 through power
drivers 90 and 91 and, thus, each valve 31 is turned on when
the flip-flops 81 and 82 are set, and they are each turned off
as their associated counter 80 overflows and resets its R/S
flip-flop. The outputs of the drivers 90 are connected to the
first, third, fifth and seventh nozzle solenoids and the
outputs of the drivers 91 are connected to the second, fourth,
sixth and eighth nozzle solenoids. As a result, nozzles 1,
3, 5 and 7 are turned on each time a pulse is produced at PIC
output terminal PC3 and nozzles 2, 4, 6 and 8 are turned on
a short time interval later (i.e. greater than 5 milliseconds
later). Each nozzle 30 is then turned off separately as their
corresponding counters 80 overflow. It should be apparent,
therefore, that the spray bar solenoids are pulsed on at the
same rate, but the duration of each is left on, and hence the
22
~ 2022~9
amount of dampening water delivered to the fountain roller 25,
is separately controllable by the value of the 8-bit binary
numbers loaded into the respective counter input registers.
Referring particularly to FIGS. 5 and 7, the speed
interface circuit 64 couples the digital incremented speed
feedback signal received from the speed sensor 36 to the PIT
60. The speed sensor 36 produces a logic high voltage pulse
for each incremental movement of the web through the printing
unit. In the preferred embodiment, a magnetic sensor model
1-0001 available from Airpax Corporation is employed for this
purpose, although any number of position feedback devices will
suffice. The speed sensor's signal is applied to a line
receiver 95 which produces a clean logic level signal that is
applied to the input of a 4-bit binary counter 96. The
counter 96 produces an output pulse each time sixteen feedback
pulses are produced by the speed sensor 36. This overflow is
applied to the clock terminal of a D-type flip-flop 97 which
switches to a logic state determined by the logic state
applied to its D input. The D input is in turn driven by a
second flip-flop 98 which is controlled by the PCO output of
the PIT 60 and the Q output of flip-flop 97.
When the press speed is to be sampled, a "1" is written
to the PC0 output of the PIT 60. This transition clocks the
20220~
flip-flop 98 to set its Q output high and to thereby "arm" the
circuit. As a result, when the next overflow of the 4-bit
counter 96 occurs, the flip-flop 97 is set and a logic high
voltage is applied to the PC2TIN and PCl inputs of the PIT 60.
The Q output of flip-flop 97 also goes low to reset flip-flop
98 and to thereby disarm the circuit. As long as input PC2TIN
is high, an internal timer 100 in the PIT 60 is operable to
measure the time interval. The input PCl may be read by the
microprocessor 42 to determine when a complete sample has been
acquired. After sixteen feedback pulses have been received,
the counter 96 again overflows to reset the flip-flop 97 and
to thereby stop the timer 100 in the PIT 60. Input PC1 also
goes low, and when read next by the microprocessor 42, it
signals that a complete sample has been acquired and can be
read from the PIT 60. The entire cycle may then be repeated
by again writing a "1" to the PC0 output of the PIT 60.
While many means are available for inputting an
indicati~n of press speed, the speed feedback circuit of the
present ~nvention offers a number of advantages. First, the
effects of electronic noise on the measured speed are reduced
by the use of the counter 96. The e~ror caused by a noise
voltage spike on the input lines is effectively reduced to
about one sixteenth the error that would result if speed were
24
20~2~59
measured by sensing the feedback pulse rate directly. In
addition, by using the timer in the PIT 60 to record the time
interval and save the result, the microprocessor 42 is not
burdened with a continuous monitoring of the speed feedback
signal. Instead, when the system reguires an updated sample
of press speed, the microprocessor checks the PIT 60 and reads
the latest value stored therein. It then initiates the taking
of another ~ample and continues on with its many other tasks.
Referring to FIG. 8, the data structures which are
employed by the preferred embodiment of the present invention
to contr~l the spray bars 26 are stored in the RAM 50. An
equivalent data structure is provided for the ink injector
system and only the data structure for the spray bars will be
described in detail. As indicated above, these data
structures are collectively referred to as the switch database
51 and the control database 52. The structure of these two
databases 51 and 52 are illustrated in FIG. 8 for one printing
couple. Similar data is stored in the databases 51 and 53 for
the other printing couple in the unit 10.
~ he swit~h ~a~t~base 51 ~ncludes an image of the switch
states on ~he ~oc~ control panel 53 (FIG. 5). The operator
depresses a "FL03~" switch when extra dampening water is to
be applied during startup. As will be described below, when
2022~9
this occurs, the dampening water flow rate is increased 25%
for a preset time interval. To support these functions, a
flood switch status word 120, a flood switch examine flag 121
and a flood timer value 122 are stored in the RAM 50. Flood
switch status 120 is updated every 100 milliseconds as will
be described below to reflect the current state of the control
panel switch. T~e other two data structures are employed to
recognize the flood request and implement the request for a
preset time interval.
When an autoflood signal is received from the press
monitor and control 38 during automatic sequencing at the
beginning of a press run, dampening water is also increased.
The status of this signal is stored at an autoflood switch
status word 123, and as long as it is present, increased
dampening water will be ~roduced. And finally, the dampening
system can be disabled by the operator and this event is
stored at 124.
A nu~ber ~f other data structures are contained in the
switch database 51 at least one of which per~ains to the
inkrate control system for the prin~ing unit 10.
T~e da~a struc~ures ~n the ~ontro~ database 52 which are
required by the da~pe~ing system are illustrated in FIG. 8.
These i~clude a control status 125 which indicates if the
202~0S9
control is in the process of making a requested change
("change in progress") or if no changes have been requested
("idle"). Control status 125 also includes a "changes not
complete counter" which indicates at any time the number of
controllable nozzles which are undergoing changes. A dampener
mode word 126 indicates if the dampening system is in either
manual or automatic mode. In the manual mode the dampening
flow rate is set to a value indicated as unit trim 127, which
can be manually altered from the master work station 11 or a
local panel 53 (FIG. 1). In the automatic mode, the dampening
water flow rate is calculated as a function of press speed in
accordance with stored rate curve data 128 as will be
described in more detail below.
A flood request flag 129 is set when the flood function
is being performed and an update flag 130 is set when a
significant change in press speed has occurred or new rate
curve data 128 has been down loaded from the master work
station 11. As will be explained in detail below, the press
speed is measured every 100 milliseconds and stored as the
instantaneous press speed 131. If the instantaneous press
speed 131 differs by more than +.5% from a processed press
speed stored at 132, then the processed press speed 132 is
updated with the newly measured value and the update flag 130
2~32~0~9
is set. The processed press speed 132 is used in combination
with the rate curve data 128 to c~lculate a new dampening
water flow rate when the dampening ~-ystem i~ in the "AUT0"
mode. This is converted to a pulse rate and is modified by
a stored couple tri~ value 133 and increased further if the
flood request flag 130 is set. The resulting current pulse
rate value is stored at 134 and is output to the timer 85 in
the PIC 70 (FIG. 6). The couple trim value 133 may be changed
from the local control panel 53 to provide a means for
manually adjusting the dampening water flow rate while in the
AUTO mode. A current % flow value stored at 137 is a nur~er
which may be read out and displayed. It expresses the current
pulse rate value 134 as a percentage of the maximum pulse rate
value and, hence, it indicates the percentage of maximum
dampening water flow rate which is currently beirg applied.
Not only is the pulse rate applied to the spray bar
nozzles 30 controlled, but also, the width of each pulse is
separately controlled. This function is supported by a nozzle
data block 135. The data block 135 stores information on each
of the eight controllable nozzles 30 which will be described
in more detail below with respect to FIG. 9C.
The rate curve data 128 is illustrated in detail in FIG.
9A. It may include one or more rate curve data blocks 140
28
~0220~9
that may be used with one or both printing couples. Each data
block 140 includes a rate curve ID 141 whi-h uniquely
identifies it. Each printing couple is associated with a
particular rate curve data block by this rate curve ID number.
As illustrated in FIG. 9B, a configuration database stored in
the RAM 50 includes configuration records 142 for each
printing couple. These configuration records 142 include a
rate curve ID number which link each printing couple to one
of the stored rate curve data blocks 140. These configuration
records 142 can be altered by messages from the master work
station 11 and, hence, the rate curve data block 140
associated with a particular printing couple can be altered
at any time.
Each rate curve data block 140 also stores a rate curve
value 143 which indicates the current dampening water flow
rate as calculated from the data in this rate curve data block
140 and the processed press speed 132. A third entry in the
block 140 is the number of rate curve points which are stored
in this data block 140 and the remainder of the data block 140
is comprised of the data which defines each of these points.
Each point is defined by a press speed number 144 and a flow
percent number 145. Anywhere from two to ten points may be
stored which indicate the desired dampening water flow rates
~ 2022Q~3
across a range of press speeds. As will be described in more
detail below, the rate curve value 143 is calculated by
linearly interpolating between the flow percent numbers 145
for the points which have press speed numbers 144 to each side
of the processed press speed 131. An example of the curves
for the control of the spray bars 26 is depicted in FIG. 12
and the curves for the control of the ink injector system is
depicted in FIG. 13.
Referrinq particularly to FIGS. 9B and 9C, each printing
couple may have up to eight separately controllable nozzles
30 on its spray bar 26. The number is indicated in the
configuration record 142 for each couple. The nozzle data
block 135 in the control database 52 stores data on each
controllable nozzle 30. More specifically, the status 150 of
each nozzle is stored (idle/change requested/change in
process). Also, stored in this block 135 is the current pulse
width value 151 which indicates the value actually being
output to the PIC 70 or 72 (FIG. 5), the desired pulse width
value 152 which indicates the pulse width which has been
commanded, and the normalized pulse width value 153 which
indicates the current value unmodified by any flood reguest
or the like. The nozzle data block 135 is employed to control
each nozzle 30 and to implement a change in the pulse width
~ ~ 2 ~ 0 5 Y
produced by each nozzle 30 in response to messages received
over the serial link 31 from the communications processor 30
(FIG. 4).
The programs which direct the operation of the
microprocessor 42 and, hence, control the operation of the
drink processor 35 are stored in the ROM 44. These programs
include a set of programs which carry out specific tasks or
processes as well as a real time clock interrupt service
routine and an operating system program.
The development of software for the microprocessor
42 can be performed in numerous different ways by one skilled
in the art. One software embodiment for controlling the spray
bar assembly 26 is disclosed in U.S. Patent 4,899,653. The
control of inking can be accomplished with a similar software
program.
The invention is not limited to the particular
details of the apparatus depicted and other modifications and
applications are contemplated. Certain other changes may be
made in the above described apparatus without departing from
the true spirit and scope of the invention herein involved.
It is intended, therefore, that the subject matter in the
above depiction shall be interpreted as illustrative and not
in a limiting sense.
