Computer controlled ink jet printing

Abstract

Variable alpha/numeric data is printed by a non-impact printing system in registered and aligned relationship with fixed data printed by a master plate cylinder on a moving web at press speeds. A programmed computer provides coded data representative of the variable data in a selected multiple line message format. Character timing signals are generated in response to the coded data and command signals from the computer represent the sequential position of the alpha/numeric data in the multiple line message format. The timing signals are automatically adjusted to accommodate different web speeds and variable form depths by an electrical top of form pulse occurring prior to the mechanical top of form of the master cylinder for each revolution thereof corrected by pulses, the rate of which is dependent on the speed of the web. The variable alpha/numeric data is printed by using the character timing signals to independently control the projection of ink droplet streams from a plurality of ink jet nozzles onto the moving web.

Description

This invention relates to both apparatus and methods for computer controlled printing presses and more specifically to such apparatus using the principle of non-impact ink jet printing whereby the variable message data can be imprinted on paper along with the printing of fixed data at press speeds. The COMPURITE printing system disclosed herein represents a combining of business forms printing press equipment and computer outputs for the simultaneous printing of a form (or direct mail advertising piece) and the imprinting of variable data. The variable data may be an address or other variable information available on the magnetic tape.

The COMPURITE system disclosed herein represents apparatus and method introducing a capability of printing at a maximum speed of 1,375 characters per second. At such speed variable information composed of 5 .times. 7 dot matrix characters may be printed on a web of paper moving at maximum press speeds. The COMPURITE apparatus disclosed herein is capable of being installed on printing presses without significantly reducing the efficiency of the existing production equipment. For example, the COMPURITE system provides significant advantages because of its modular characteristics which enhances its portability. It may be installed on multiprinter flexographic printing presses for producing a wide variety of products and sizes.

Flexography is a rotary, relief printing process employing fast drying, evaporating, solvent inks and usually flexible rubber printing plates. It is this ink distribution and transfer system made mandatory by such inks, the comparatively inexpensive printing plates, and the great advantage of quick and simple roller cleanup and press setup in changing from one job to the next, which sets flexography apart from the run-of-the-mill letterpress printing and makes it especially adaptable to high speed, low cost, in-line printing with converting machinery. Within reasonable limits, changes in size of the printing repeat can be accomplished economically and with insignificant waste. By mounting plates on printing cylinders of different circumferences and changing the spacing across the cylinders, size variations can be made in both the length and width. This interchangeability of plate cylinders (as well as their size) is the basic difference between flexography and conventional rotary letterpress. It allows the printer to make-ready off press while running other work; downtime is minimized.

SUMMARY OF THE INVENTION

FIG. 1 illustrates in block diagram form the basic components of the COMPURITE I ink jet printing system. Variable data information to be printed by the ink jet nozzles in registration with fixed form data printed by a plate cylinder are stored in magnetic tape unit 30 on two magnetic tapes identified as unit 0 and unit 1. The variable data is formatted so that the data therein can be read into, and under the control of, computer 31. Computer 31 assembles the variable data into an alpha/numeric character message format for distribution to computer interface 33. Computer 31 has the capability of reading the magnetic tapes, storing the data thereon and providing the basic data control and program sequencing functions for formulating the variable data input to computer interface 33. Computer 31 includes the necessary input/output system and data bus lines for communication between computer interface 33 and CRT operator control and display 32.

CRT operator control and display 32 comprise at least a CRT display unit for visually displaying information to a system operator and an associated keyboard by which the operator may establish a dialog with the computer for the insertion of necessary data and information to establish various system parameters necessary for the operation of the COMPURITE I system. The CRT display also provides the operator with information generated by the computer concerning the operation of the system.

Forms position and web speed 34 includes the necessary transducers, such as optical encoders, for providing data relating to the desired form depth, web speed, and rate of rotation of a master printing cylinder. The web speed and rate of revolution of the master cylinder provide necessary timing pulse inputs to computer interface 33 so that the interface can provide the necessary timing and control signals for coordinating the operation of computer 31 and nozzle electronics 35 for printing the alpha/numeric characters in aligned and registered relationship on the moving web.

Computer interface 33 includes the necessary circuitry for receiving transducer signals from forms position and web speed 34, data control and sequencing information from computer 31, and status signals from nozzle electronics 35 and nozzles 36 to synchronize and aid in controlling the operation of the entire COMPURITE I system. Computer interface 33 essentially comprises five basic sub-components which respectively generate various control and synchronization signals for internal utilization within the interface itself and for the operation of the nozzle electronics. For reasons which will become more apparent with the subsequent discussion of the ink droplet formation and projection of the ink droplets in registered position on a moving web, the speed of which is variable as desired, it is necessary to control the time of ink droplet release as a function of web speed. Computer interface 33 includes Top of Form Controller circuitry for precisely controlling the ink droplet release as a function of the web speed and the top of form of the master plate cylinder. Its output, a corrected top of form pulse (CTOF) represents a basic control signal within the interface which is used as a reference from which all the character strobe and timing signals within the Interface are generated for the subsequent control of the nozzles within a print unit or print units. The CTOF is also adjusted in accordance with a desired form depth which is selectable by the operator whereby the variable information printed by the ink jet nozzles can be displaced or registered with respect to various form depths on the master cylinder.

Computer interface 33 includes a Master Head Controller for each print unit. The Master Head Controller receives heading distance information from the computer and generates the necessary timing signals to control the ink droplet release from the first nozzle in each print unit with which the Master Head Controller is associated. These timing signals are generated by counting clock pulses having a rate which is variable in direct proportion to the web speed. The operation of the Master Head Controller is controlled by the CTOF pulse. The timing signals comprise character strobe pulses (STRI pulses) for providing a reference frame within which are formed five spaced character stroke strobe pulses (STR2 pulses) in which each of the STR2 pulses "times" the release of a respective column of the 5 .times. 7 matrix from which all of the alpha/numeric characters in the COMPURITE I system are generted. The Master Head Controller also generates additional timing signals which provide control functions to Head Controllers 2, 3, 4 and 5 of its associated print unit. The Master Head Controller also generates a print request signal, prior to the actual time of droplet release, for the nozzle electronics so that the No. 1 nozzle of that printing unit can be primed for printing.

Computer interface 33 further includes common Head Controller circuitry for receiving a device address signal and control functions for operating the Master Head and Head Controllers 2, 3, 4 and 5 of a print unit. These control functions comprise DISABLE, ENABLE, STOP PHASING, and START PHASING signals as well as a start signal from the computer which synchronizes the operation of the Master Head Controllers of each print unit as well as the operation of the remaining four Head Controllers for each print unit.

The computer interface 33 further comprises identical circuitry for each of the second, third, fourth and fifth Head Controllers of each print unit to generate timing signals for controlling the respective droplet release from each of the associated nozzles 2, 3, 4 and 5 of that print unit. These timing signals also comprise character strobe pulses (STR1 pulses) and character strobe pulses (STR2 pulses) which perform the same function as the same named pulses generated by the Master Head Controller. However, the character strobe and stroke strobe pulses from the respective Head Controllers 2, 3, 4 and 5 are generated to account for the displacement along the axis of web movement of the nozzle within a print unit. That displacement is fixed during any given printing operation, but may be varied within the mechanical limitations of the nozzle structure and the format which is desired to be printed. In other words, the spacing between the nozzles along the axis of the moving web may be varied as well as the respective spacing of the nozzles along an axis transverse to the axis of web movement. Each of Head Controllers 2, 3, 4 and 5 includes suitable circuitry for timing the generation of the character strobe and stroke strobe pulses to account for the spacing between the nozzles in the direction of web movement. Each of the head controllers includes circuitry for generating a print request signal which is delivered to its associated nozzle to "prime" the associated nozzle for printing.

Head controller circuitry identical to all the head units is provided within computer interface 33 to count the number of characters printed by each nozzle so that end of message control signals can be generated to terminate the generation of the character strobe and stroke strobe pulses within the Master Head Controller and Head Controllers 2, 3, 4 and 5 of each of the print units as well as to signal the computer that the printing of a particular variable set of data has been completed. This circuitry also generates register strobe signals for controlling the output of coded alpha/numeric character data to the nozzle electronics.

The nozzles of each print unit are associated with a set of storage and print buffers which are responsive to respective register strobe signals from the Common Head Controller Circuitry for strobing the character data from the computer data bus to a seven line output representing a given character by a seven bit ASCII code. Each of the nozzle controllers includes addressing, sense line, and data control circuitry for controlling the receipt of information from the computer and for providing a means of communicating with each of the nozzles whereby the computer can determine their respective status for printing.

The printing format of the embodiment disclosed herein includes a length of thirty-eight characters in each of the lines of printing. The embodiment also utilizes a displacement of ten characters per inch of web movement. The spacing of the lines between the printing nozzles of a given print unit and between the print units themselves, is variable and limited only by the mechanical configuration of the press, the mounting of the mechanical structure of the print units, etc.

Nozzle electronics 35 receives the coded alpha/numeric character data output as well as the character STR1 and STR2 pulses of computer interface 33, whereby the printing of the alpha/numeric characters from each of the nozzles within a print unit is controlled. A matrix generator for each of the nozzles provides a stream of pulses synchronized with respect to the generation of ink droplets in the nozzles themselves. The pulse stream is timed by the character strobe pulses from the computer interface so that each column of the 5 .times. 7 matrix is timed to release the droplets in registered and aligned relationship on the moving web regardless of its speed.

The pulse stream output from each matrix generator is converted by digital-to-analog conversion circuitry, a separate circuit being responsive to each of the matrix generators, whereby a low level video ramp signal representing seven different voltage levels for each column of the matrix is produced. The low level video signals are amplified and provided as control voltages to a charging tunnel whereby each of the successive drops in the droplet stream projected from each nozzle is charged in accordance with its desired displacement along an axis transverse to the movement of the web. The video amplifier is synchronized with the excitation of a piezoelectric crystal which forms the droplets in each of the nozzles so that the droplet charging is properly phased with the generation of droplets.

Nozzle electronics 35 also includes high voltage deflection circuitry for placing a static charge on the charging plates of a deflection tunnel through which each of the charged droplets passes, thereby deflecting each droplet a distance directly proportional to the charge placed on each respective droplet during its passage through the charging tunnel. Uncharged droplets are not deflected and are intercepted by a collector prior to their impingement on the web so that they play no part in the printing of the alpha/numeric characters.

The nozzle electronics 35 also includes well-known phasing and droplet sensor circuitry for sensing the phasing of the ink droplets and to correct that phasing should it require correction.

Finally, the COMPURITE system includes means for controlling the ink supply and flow of ink to each of the respective nozzles and that system is designated by numeral 37 in FIG. 1. The print units each include an ink supply manifold whereby each of the five nozzles in a print unit are parallelly supplied with ink from ink reservoirs. The uncharged ink droplets which are intercepted by each of the respective collectors associated with each of the nozzles are withdrawn by a manifold vacuum return connected to each of the collectors. The ink system 37 also includes appropriate filters and pressure regulators to assure a proper supply of ink to each of the ink jet nozzles.

OBJECTS OF THE INVENTION

The primary object of the invention is to provide a computer controlled printing system using ink jet technology whereby variable data messages may be printed in registered and aligned relationship with respect to fixed data information printed on the moving web by a master press cylinder.

A second object of the invention is to provide such a computerized printing system wherein the variable data is printed using ink jet printing technology wherein all of the alpha/numeric characters of the variable data are generated from a 5 .times. 7 character matrix.

It is a third object of the present invention to provide computer interface circuitry between the computer and ink jet print nozzles for controlling the timing of the ink droplets in accordance with variable web speed.

It is a fourth object of the present invention to provide computer interface circuitry for controlling the transmission of coded character data information from the computer to the nozzle electronics in accordance with variable web speed and heading distance information from the computer.

It is a fifth object of the present invention to provide the necessary alpha/character timing signals to the nozzle electronics whereby the electrical signals for defining the character matrix for each alpha/numeric character are determined so that the alpha/numeric characters are printed in aligned and registered relationship on the moving web.

It is a sixth object of the invention to provide computer interface circuitry wherein the registration and alignment of the printing of the alpha/numeric characters from each of a number of ink jet nozzles is selectively varied in accordance with the form depth of the master printing cylinder.

It is a seventh object of the invention to provide computer interface circuitry of the type specified herein which is capable of simultaneously controlling a plurality of ink jet nozzles whereby alpha/numeric data is printed from the nozzles in aligned and registered relationship with the form depth on a master cylinder.

It is an eighth object of the present invention to provide computer interface circuitry of the type specified herein for the generation of character strobe signals which are automatically adjusted in accordance with the variable speed of a moving web, the selected form depth, heading distance data provided by the computer, and to compensate or account for the spacing of the individual printing nozzles with respect to one another along the axis of movement of the web.

It is a ninth object of the present invention to provide computer interface circuitry of the type specified herein which is responsive to address, control commands and data information from a computer which assembles the variable data in accordance with a given message format, for generating character printing timing signals to time the release of ink droplets from a plurality of ink jet nozzles whereby alpha/numeric characters may be printed in aligned and registered relationship with a master printing cylinder over a wide range of press speeds.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 illustrates in block diagram form the components of the COMPURITE I system;

FIG. 2 illustrates the configuration of a print unit illustrating the relationship of the five printing heads thereof and a five-line print output with each line being printed by a respective head or nozzle;

FIG. 3 shows an exemplary embodiment of three print units each consisting of five staggered heads for respectively printing different variable information on different portions of a moving web and also figuratively shows the relationship of the print units to a print cylinder for printing a form wherein the variable data are in registered position with respect to the plate cylinder;

FIG. 4 shows a representative matrix font consisting of 64 alpha/numeric characters each of which is configured within a 5 by 7 matrix;

FIGS. 5A and 5B are circuit schematics of the interface top of form controller;

FIG. 6 is a schematic representing the interface head controllers common computer address circuitry;

FIG. 7 is a schematic of an interface master head controller;

FIG. 8 illustrates a schematic of interface head controllers 2, 3, 4 and 5;

FIG. 9 is a schematic representative of the interface head controllers common end of message circuitry;

FIG. 10 represents the circuit schematic for common interface nozzle controller circuitry;

FIGS. 11A and 11B respectively show gating circuitry used in the computer interface;

FIG. 12 shows the operative relationship between the interface schematics represented by FIGS. 5A, 5B and 6 to 10;

FIG. 13 is a side view of the plate cylinder showing the form depths and the encoder slits used in timing the print nozzles;

FIG. 14 illustrates the relationship of various control signals of the computer interface as a function of a given press speed;

FIG. 15 is a combined block diagram and functional representation respectively of the nozzle electronics and an ink jet nozzle showing the interrelationships between the electrical signals for operating the nozzle and the relationship of the ink droplet stream with respect to the elements of the nozzle and the moving web;

FIGS. 16A through 16G illustrate the principle of operation of the nozzle electronics;

FIG. 17 shows the ink supply manifold and vacuum manifold assembly for a five-nozzle print unit which forms part of the ink system; and

FIG. 18 is an illustrative embodiment of the ink supply regulator forming part of the ink system.

DETAILED DESCRIPTION

FIG. 2 illustrates a typical print unit 38 of the COMPURITE I system in operative association with a moving web 39. Each of the five ink jet nozzles 38a, 38b, 38c, 38d and 38e of print unit 38 is mounted to print a respective line of print 40a, 40b, 40c, 40d, and 40e. As illustrated in FIG. 2, each of the print lines 40a to 40e are equally spaced from one another; however, the interline spacing may be varied by suitably adjusting the mounting of a desired one or all of ink nozzles 38a to 38e in a direction transverse to the movement of web 39. In the COMPURITE system described herein, each of nozzles 38a to 38e is spaced a distance D from an adjacent nozzle in a print unit 38. The distance D is two and one-half inches for the system as described herein. However, such a mounting relationship of the respective nozzles within a print unit is only exemplary, and it is understood that the spacing D between each nozzle may be varied if desired by a suitable modification of the interface circuitry as will be apparent from the desription herein of its structure and operation.

In an operative embodiment and in actual use, the ink jet nozzles of the COMPURITE I system lie in a horizontal plane with the moving web 39 moving in a vertical plane. However, the positions of the print unit and the moving web in the horizontal and vertical planes may be interchanged, if it is recognized that poor results are obtained when the ink jet nozzles are required to emit their droplets against the force of gravity. Each of the ink jet nozzles 38a to 38e lies in a plane normal to the plane of moving web 39.

FIG. 3 illustrates a three-print unit ink jet printing system comprising print units 38, 38' and 38". Each of the print units 38, 38' and 38" includes five ink jet nozzles respectively designated as 38a to 38e, 38' to 38e' and 38a" to 38e". Moving web 39 is illustratively driven by drive rollers 41a, 41b in the vertical direction indicated in FIG. 3. The mounting structure for each of print units 38, 38' and 38" is not shown in FIG. 3 to avoid cluttering the drawing. The print units may be mounted by any suitable mounting structure so that they are in proper spaced relationship to moving web 39.

Continuing with FIG. 3, master print cylinder 40 is illustratively shown in operative relationship with print and drive roller 41a. However, the relationship of print cylinder 40 to print roller 41a and print units 38, 38', 38" is only exemplary. Master print cylinder 40 may be located further downstream from the moving web 39 than is depicted in FIG. 3. It is also understood that master print cylinder 40 may be located upstream of print units 38, 38', 38". The mechanical top of form of master print cylinder 40 is illustrated in FIG. 3. Displaced from the mechanical top of form is a slit 41 from which electrical top of form pulses may be produced by suitable optical encoder circuitry which is well known to those skilled in the art. A number of slits 42 are provided around the periphery of master print cylinder 40 to generate a fixed number of timing pulses for each revolution of the master cylinder. In the embodiment described herein there are 2500 slits 42. Suitable electrical pulses are generated by optical encoder mechanism associated with slits 42. The electrical top of form pulse as well as the 2500 pulses per revolution of print cylinder 40 are inputs to the interface circuitry to provide the necessary timing functions for the operation of that circuitry. Additionally, a transducer is provided to generate clock pulses for the Interface at a fixed number of pulses/inch of web travel. Such a transducer is not shown in FIG. 3, but may comprise any well-known speed transducer such as is normally used with the drive and gear train mechanism of printing presses to indicate its speed.

The spacing between print units 38, 38' and 38" can be varied to provide any desired variable data printing format on the forms printed by the master cylinder. It is also understood that the lateral spacing of print units 38, 38' and 38" can also be adjusted as desired in a direction transverse to the movement of web 39, whereby the printing from each of the respective print units in relationship to the form or forms on master plate cylinder can be adjusted as desired.

With each of print units 38, 38' and 38" mounted in a fixed spatial relationship with the master print cylinder 40, the COMPURITE I system includes form depth selection by the operator and the COMPURITE interface circuitry automatically adjusts the generation of the character strobe pulses to cause the ink jet printing to be registered and aligned in accordance with the form depth selected.

FIG. 4 illustrates an exemplary alpha/numeric matrix font comprising a total of sixty-four alpha/numeric characters. As is evident from FIG. 4, each of the alpha/numeric characters is generated by a 5 .times. 7 matrix as will be more clearly understood from the description which follows. Each ink jet nozzle is capable of producing each of the sixty-four alpha/numeric characters illustrated in FIG. 4. It is understood that the character font in FIG. 4 is only exemplary and that other type fonts may also be used with the COMPURITE I system described herein.

THE COMPUTER HARDWARE, SOFTWARE, FUNCTIONS AND OPERATIONS

As the COMPURITE I system is described herein, the variable information (e.g., mailing addresses) to be printed on a form must be recorded on an input device such as a magnetic tape, paper tape, card, etc. It is understood that if the input, for example the information stored on magnetic tape, is not compatible with the COMPURITE requirements as described herein, the data may be converted from the customer's tape format to the COMPURITE format by any of the well-known conversion techniques. In order to make such a conversion it is necessary to know the record layout of the magnetic tape to be converted. It is also imperative to know precisely what information is required to be printed, where it is located on the tape, and the required format of the COMPURITE printing.

For the purposes of the present description the alpha/numeric characters are set in ASCII (American Standard Code for Information Interchange). Table I defines the ASCII character set for the 64 character font described herein.

TABLE I ______________________________________ ASCII Character Set 8 ------------- 1 1 1 1 7 ------------- 0 0 1 1 BITS 6 ------------- 1 1 0 0 5-------------0 1 0 1 4 3 2 1 ______________________________________ 0 0 0 0 Space .phi. P 0 0 0 1 ! 1 A Q 0 0 1 0 " 2 B R 0 0 1 1 # 3 C S 0 1 0 0 $ 4 D T 0 1 0 1 % 5 E U 0 1 1 0 & 6 F V 0 1 1 1 ' 7 G W 1 0 0 0 ( 8 H X 1 0 0 1 ) 9 I Y 1 0 1 0 * : J Z 1 0 1 1 + ; K [ 1 1 0 0 , < L 1 1 0 1 - = M ] 1 1 1 0 . > N 1 1 1 1 / ? O -- ______________________________________

The following are exemplary specifications for magnetic data tapes for the COMPURITE requirements as defined by the exemplary embodiment herein described: 9 level (9 track), ASCII (American Standard Code for Information Interchange), packing density -- 800 bpi, odd parity, standard reel = up to 2400'. Approximately 90,000 (190 character) messages per reel.

Exemplary of other data formats are a seven level BCDIC (Binary Coded Decimal Interchange Code) having even parity, and a packing density of 800 BPI (bits/inch); or a nine level, EBCDIC (Extended Binary Coded Decimal Interchange Code) with a packing density of 1600 BPI. The aforementioned data formats, or any other data formats, may be converted to the above described data format used in the embodiment herein by conversion techniques and apparatus which are presently available.

A. the first block after the load point on each tape is a twenty character header shown as follows:

0-1 ID -- The letters "ID" are the first two characters on the magnetic tape.

2-5 XXXX -- A 4 digit tape sequence number (0001-9999).

6-19 Blanks -- Minimum total header area should be 20 print positions.

B. all magnetic tape data blocks are 2280 ASCII characters long except for the header.

C. end of tape reflectors result in switching to the other magnetic tape drive. Any block written over the end of tape reflector is processed. No new data blocks are read beyond this point.

TABLE II __________________________________________________________________________ BASIC MAGNETIC TAPE FORMAT __________________________________________________________________________ Load 20 Character L I 2280 L I 2280 L I 2280 End of Tape Point Header R R Character R R Character R R Character Reflector (A) C G Block (B) C G Block (B) C G Block (B) (C) __________________________________________________________________________ LRC-Longitudinal Redundancy Check? IRG-Inter-record Gap (1/2 - 3/4 inches)

D. the last tape of the run must have a file mark occurring after the last data block. This designates the end of the file.

TABLE III ______________________________________ LAST TAPE FILE MARK ______________________________________ L I 2280 Character File R R Block Mark C G (B) (D) ______________________________________

TABLE IV __________________________________________________________________________ FORMAT OF THE 2280 CHARACTER BLOCK __________________________________________________________________________ 190 Character 190 Character 190 Character 190 Character 190 Character Message Record Message Record Message Record Message Record Message Record (1) (2) (3) (11) (12) 190 380 570 2090 2280 __________________________________________________________________________

TABLE V ______________________________________ FORMAT OF EACH 190 CHARACTER MESSAGE RECORD ______________________________________ Line Line Line Line Line 1 2 3 4 5 38 76 114 152 190 ______________________________________

E. table VI shows an example of a single 190 character message format as it would appear on the tape.

TABLE VI ______________________________________ 190 CHARACTER MESSAGE - AS APPEARING ON TAPE ______________________________________ Line 1 .alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alp ha..alpha..alpha.OMEGA.alpha.TOWNSHIP.alpha..alpha..alpha..alpha..alpha..a lpha..alpha..alpha..alpha..alpha..alpha..alpha. Line 2 JAN.alpha.1,.alpha.1973.alpha..alpha..alpha..alpha..alpha..alpha..a lpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha.June.alpha.3.phi.,.a lpha.1973 Line 3 .alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alp ha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha.. alpha..alpha.$.alpha..alpha..alpha..alpha..alpha..alpha..phi.,.phi..phi..p hi..alpha..alpha..alpha..alpha. Line 4 .alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alp ha..alpha..alpha..alpha.14.alpha.3.alpha..phi.61.alpha..phi.1.phi..alpha.. alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alph a..alpha. Line 5 OMEGA.alpha.TOWNSHIP.alpha..alpha..alpha..alpha..alpha..alpha..alph a..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..alpha..a lpha..alpha..alpha..alpha..alpha..alpha..alpha. ______________________________________

It is noted that the symbol .alpha. is the ASCII space code. Additionally, the character message is thirty-eight characters per line. All 190 print positions must be represented by either a space or a character.

The COMPURITE I system in existence at the time this application was filed utilizes a Varian 620 100 Minicomputer, the structure and operation of which is known to those skilled in the art. The Varian 620 100's Computer Handbook distributed by Varian Data Machines, a subsidiary of Varian, fully describes the structure and operation of such machines including the software and input/output controls and functions. However, it is understood that any computer, whether general purpose, special purpose, hard wired, etc., could be used to assemble the printing program and to provide the necessary control functions defined hereinafter. Furthermore, it is understood that the software, including the program necessary to operate the computer, while not in and of itself forming a part of this invention, would be apparent to one having ordinary skill in the computer art from the functions and operations described herein which are performed by the COMPURITE I system.

In general, the computer must have a central processing unit (CPU) including a memory, the equivalent of read and write registers, a magnetic tape unit (MTU) controller, and an input/output (I/O) system which is capable of addressing, controlling, delivering, and receiving peripheral device information. For example, the I/O system would include hardware enabling interrupt of the CPU operations by the peripheral controller to initiate servicing of interrupt routines.

Additionally, the COMPURITE I system as described herein uses a CRT (cathode ray tube) keyboard input/output device to provide operator control of the system and as a means for inserting the necessary data requested by the computer and displayed on the CRT for program operation. Dialog with the computer is typed into the CRT via a question/answer format utilizing the CRT and the keyboard. A teletype may also be used as a back-up for the CRT and also as accessory which provides the means to use a paper tape with the computer. A paper tape, for example, may be used occasionally during trouble-shooting procedures.

The tape drives may comprise two 25 inch per second (IPS), 800 bits per inch (BPI), nine track units. Two tape units are used to enable automatic switching from one tape to another when the first tape is depleted without losing continuity. The operator then replaces the depleted tape to be ready for switching from the second tape to the new tape when the second tape is depleted.

When a magnetic tape has been completely processed and a switch to the other magnetic tape unit has been completed, the following message is output:

MT u MNT NEW TAPE

where u is the magnetic tape unit, either 0 or 1. The operator unloads the old tape and loads a new tape on the unit (brings it to the load point and puts it ON LINE) and types the following message:

;NEW TAPE MNTD MT u.

The computer verifies that the magnetic tape is ON LINE and that it is actually a new tape. If not, the following message is output:

NEW MT NOT MNTD

If this message is output, either the new magnetic tape mounted message was typed prematurely, a new tape has not been mounted or a hardware problem exists because the unit has not come ready at the load point. The mount new magnetic tape message is output again and the operator should take the appropriate action.

If the operator desires to switch to a new magnetic tape unit before a complete magnetic tape has been processed, because of magnetic errors, the following request should be typed:

;SWITCH TO MT u

where u is 0 or 1.

INITIALIZE AND START-UP PROCEDURES

1. NO. OF PRT UNITS

Input the number of 5-Nozzle print units. Acceptable inputs 1, 2 or 3.

2. LINES PER MSG.

Input the number of lines per message. Acceptable inputs 1 through 15. Inputs 1 through 5 result in lines/message equal to 5; inputs 6 through 10 result in lines/message equal to 10; and inputs 11 through 15 result in lines/message equal to 15. Thus, the lines/message on the magnetic tape must be a multiple of 5. Any non-used lines on the magnetic tape must be blank filled. NOTE: 5 lines/message and number of PU = 1, 2 or 3 acceptable; 10 lines/message and number of PU = 2 or 3 acceptable; 15 lines/message and number of PU = 3 acceptable.

3. ENT FRM LAG 1-2

This request is output only if the number of Print Units is 2 or greater. This is the number of forms between Print Unit 1 and Print Unit 2. Acceptable inputs 0 through 23. Input of 0 through 23 acceptable if lines/message equal 5. Input of 0 through 11 acceptable if lines/message equal 10. Input of 0 through 7 acceptable if lines/message equal 15.

4. ENT FROM LAG 2-3

This request is output only if the number of Print Units is 3. This is the number of forms between Print Unit 2 and Print Unit 3. The Form Lag between Print Units 1 and 2 is added to the Form Lag between Print Units 2 and 3. This total Form Lag is evaluated. A total Form Lag of 0 through 23 acceptable if lines/message equal 5. A total Form Lag acceptable 0 through 11 if lines/message equal 10. A total Form Lag acceptable 0 through 7 if lines/message equal 15.

5. ENT TOF DIST Hx

Input the distance in pulses/inch. There are 120 pulses/inch; thus, 1 inch equals 120 pulses. The input of 240 pulses/inch or 2 inches is the minimum input and the input of 2220 pulses/inch or 18.5 inches is the maximum input. A request for each Head (set of the same Nozzles number from each Print Unit) is made and must be answered.

6. SWITCH CODE POS

The Switch Code -- any two adjacent characters (word) within a message -- used to effect a Suspend if the code changes from one block of data to the next.

Input of "0" -- don't check Switch Code

Input of "+" and number -- Check the Switch Code and always print it.

Input of "-" and a number -- Check the Switch Code, but never print it.

Input of a number only causes an error.

The number input is the positional location within the message of the two characters. These two characters must be within a computer word, i.e., the two characters must not cross a computer word boundary or if starting to count the characters, the first character must be an odd count like 1, 3, 5 . . . thus, the number input is either one of the two characters when counting starts with 1. Example -- If the Switch Code is in the first two characters of the message, then 1 or 2 should be input. If the length of one message is 5 lines and the Switch Code is in the last two characters of the message, then 189 or 190 should be input.

7. MSG PRINT CNT

Input the number of times each message is to be printed. Valid inputs are 1 through 32768. If each message is to be printed only once, input 1; if each message is to be printed twice, input 2 and so on. Once this input is complete, phasing of each Nozzle is checked. If the Nozzle is not phasing properly, the message "NOZ x-y PHSE ERR" is output, but processing continues. NOTE: "x" is the Print Unit 1 to 3 and "y" is the Nozzle 1 to 5.

8. ENT ACTV MT

Input the active magnetic tape unit number. The input must be "0" or "1" depending on which magnetic tape unit the data is to be input from. When the input is made, the unit must be ready; i.e., the data tape must be mounted and ready. If the unit is not ready, the message "MT .times. NOT RDY" is output and the request reissued.

9. ENT MT SEQ NO

Input the sequence number to which the data tape is to be positioned.

a. An input of "0" leaves the tape positioned where it is.

b. An input of "-" and a number backspaces the data tape the number of blocks specified.

c. An input of "+" and a number skips forward the data tape the number of blocks specified.

d. An input of a number only rewinds the data tape, inputs the ID block and skips forward the number of blocks specified.

10. SS1 UP-TEST/DOWN-PROD SELECT FORM DEPTH

The CPU halts after this message is output. The operator should set sense switch 1 up to Test or down for Production. He should also select the appropriate Form Depth. Once these have been selected, the COMPURITE System is ready for operation. Depression of a "Run" switch will then start the COMPURITE operation.

OPERATOR REQUESTS

The following operator/computer dialogs may be activated randomly in time whenever printing is being executed. For these requests, a semicolon (;) is input first. This input informs the system that an operator initiated request is to follow. A period (.) is required to terminate the request.

1. Operator Request Formats

In order for any requests to be accepted by the computer, all the characters, except for spaces, must be typed in the correct order. For example, the following request is acceptable:

; N E W M T M N T D.

However, the following request is invalid and results in the computer outputting an error message:

;STP.

WHAT??

;STOP.

When the error message is output, the input has not been accepted by the computer and the operator must type the request again in the correct form.

2. Operator Requested Suspend and Shutdown

The operator is permitted to suspend the printing operation for an indefinite period of time. Upon receipt of this request the computer discontinues reading data from the active magnetic tape unit, but continues the printing operation by outputting blanks. The Suspend is used to discontinue the printing of data for roll changes. The suspend MUST be effected before the press stops for the roll change. To effect the suspend, the operator types:

;SUSP.

The operator may resume the printing of data from the tape by typing the following:

;CONT.

The operator is permitted to request a shutdown, that is, terminate reading of the magnetic tapes and disable the printer system. To do this, the operator types:

;STOP. ;STOP.

Upon receipt of this request the computer terminates reading of the magnetic tape, outputs all messages currently stored in the computer, disables the printer system and outputs the following:

MT u ID aaa SEQ NO yyyyy SHTDWN CMPLT

where u is the magnetic tape unit, either 0 or 1, aaaa is the ID number and yyyyy is the sequence number of the last data block processed. A shutdown is used at the end of a job, or at the end of a shift. Again, the shutdown must be effected before the press is stopped.

3. Operator Requested Display

The operator may display the first message of the next data block that is input from the active data tape by typing the following request on the operator communication device:

;DISP.

This request has no effect on the output of the data to the Print Units; it is simply a means of displaying a message.

The previously described tape unit messages are also part of the operator request messages.

OPERATOR ALERT MESSAGES

The following operator alert messages are output to the operator communication device (the TTY or CRT).

1. mt u NOT RDY, where u is either 0 or 1.

1. Not READY status on the current unit. At least one record has been read successfully from this tape unit since the last unit switch but now the unit is not ready.

2. When a magnetic tape unit switch is required and the unit being switched does not have a load point and a ready or ON LINE status.

2. PHSE ERRS

H1 h2 h3 h4 h5

zz zz zz zz zz where zz is the number of errors. A phasing error occurs when it is time to begin printing a new line at a nozzle but the nozzle status is not ready. When this error occurs, the data is processed as though the error did not occur, thus, poor character information may occur. There are five HEAD PHASE ERROR Interrupts in this subsystem. This type of interrupt occurs when printing of a new line is to start but phasing has not stopped. When one of the errors occurs, an error count for the interrupting head is incremented by one. When this count reaches ten for any one head or a total of 20 for all heads, an operator alert message is output. Once this message has been output, all five counts are reset to zero. In addition, the printer Data Ready Interrupt still occurs and data is output although phasing has stopped.

3. MT u BAD DATA ccc

where u is either 0 or 1 and ccc is the number of bad data blocks. A magnetic tape error occurs when a data block cannot be read correctly from the tape. When a data block cannot be read, an error count is incremented. This count and the unit number are output to the operator communication device to inform the operator of a potentially bad magnetic tape. When this error occurs, the data is processed as though the data were read correctly. Thus, erroneous data may be output to the printer system. This may be eliminated by an appropriate control function performed by the software.

4. MT u TIMEOUT

where u is either 0 or 1. A special program is responsible for recognizing when the peripheral devices are not responding to input/output request calls. When an error occurs the message is output to inform the operator of a potential problem.

5. PWR FAIL RECOVERY MT u ID aaaa SEQ NO yyyyy

When power is restored after a power failure, an alert message is output to inform the operator of the occurrence. After the message is output, Start-up is automatically entered. The magnetic tape unit, ID number and sequence number of the last data block processed are given for use in the Start-up procedure.

6. New Switch Code

If the following message is output, a new Switch Code has been detected and a Suspend has been effected.

NEW SWITCH CODE xx

"xx" represents the new Switch Code.

COMPUTER CONTROL FUNCTIONS AND INPUT/OUTPUT SYSTEM

The computer hardware includes a priority interrupt module (PIM) which enables peripheral controllers in the system to interrupt the central processing unit (CPU) operations for initiation of the servicing of interrupt sub-routines. A buffer interlace controller (BIC) permits the peripheral equipment to transfer data directly to or from the computer memory. In the embodiment described herein the BIC is associated with the Magnetic Tape Subsystem whereby the Magnetic Tape Interrupt Response routine may be entered.

The input/output system (I/O) utilizes a bi-directional I/O bus, thereby enabling one set of data and control lines to communicate with all the system peripherals. All the peripheral controllers and I/O options are connected to the I/O bus.

The computer communicates directly with the peripheral equipment by the transmission of an external control instruction and a peripheral device address to the selected controller via the I/O bus. A sense line associated with a given peripheral indicates whether that peripheral is ready to send or receive information, whereby the computer requests the peripheral device to place a word of data, or to accept a word of data placed by the computer, on the I/O bus. The following is a description of the I/O bus line.

E bus

The E bus comprises a sixteen-bit, parallel, bi-directional I/O channel (EB00 through EB15) and is used for the transmission of external control instructions, device addresses, and data from the computer to the peripherals. The peripherals utilize the E bus to transmit data to the computer and E bus signal is true when it is at 0 Vdc and false at + 3 Vdc.

CONTROL LINES

FRYX: This is a computer generated signal for indicating that an external control instruction and a device address have been placed on the E bus. Each peripheral controller examines the device address, and upon the true-to-false transition of FRYX, the addressed peripheral responds to the external control instruction. FRYX is true at 0 Vdc and false at +3 Vdc.

DRYX: This signal indicates that the computer has placed data on the E bus, or that it has accepted the data placed on the E bus by the peripheral. The transfer occurs upon the true-to-false transition of DRYX. DRYX is true at 0 Vdc and false at + 3 Vdc.

IUAX: A computer generated signal to acknowledge the receipt of an interrupt function. The interrupting peripheral controller can communicate an address to the computer and can receive data from, or send data to, the computer when IUAX is true. IUAX also inhibits the device address decoding in all controllers during the address phase of an interrupt operation thereby preventing the controllers from interpreting any part of the memory address as a device address.

SYRT: This signal initializes all of the peripheral controllers connected to the I/O bus. SYRT is true when the computer resets. SYRT is true at 0 Vdc and false a + 3 Vdc.

SERX: This signal is a controller response to a program sense instruction, during the execution of which the computer places a function code and a device address on the E bus. The address controller is instructed to indicate the status of a peripheral device action and if that action can be performed, the controller responds by setting SERX true.

I/O OPERATIONS

In the computer system, information transfers occur under the control of a stored program or they may be interrupt-initiated.

The I/O system provides four types of I/O operations under program control. These operations are:

a. external control. An external control code which specifies a specific peripheral function and a device address is transmitted from the computer to a peripheral controller.

b. program sense. The status of a selected peripheral controller sense line is interrogated by the computer.

c. input data transfer. One word of data is transferred from a peripheral controller to one of a number of registers or a location in memory.

d. output data transfer. One word of data is transferred to a peripheral controller from one of a number of the computer registers or a location in memory.

Under program control, the I/O system communicates directly with all of the peripherals. The transmission of an external control function code and a proper device address to the selected controller via the I/O bus initiates peripheral operation. The computer determines when a peripheral is ready to send or receive information by interrogation of its associated sense line. A peripheral may be requested to place a word of data on the I/O bus during a computer input transfer, or to accept a word of data placed on a bus by the computer during an output transfer.

TABLE VII __________________________________________________________________________ E BUS AND I/O CONTROL SIGNAL __________________________________________________________________________ External Interrupt OPERATION> Control Sense Data Transfer Trapping Sequence Sequence __________________________________________________________________________ TPOX-I or TPIX-I FRYX-I* IUAX-I, IUAX-I, IURX-I CONTROL FRYX-I* SERX-I* FRYX-I* DRYX-I FRYX-I DRYX-I IUAX-I Line > (Phase 1) (Phase 1) (Phase 1) (Phase 2) (Phase 1) (Phase 2) (Phase __________________________________________________________________________ 1) EBOO-I EBO1-I EBO2-I Device Device Device address address address EBO3-I EBO4-I Pairs of signals EBO5-I Data Address Data used for specific EBO6-I interrupts Function Function EBO7-I code code Not EBO8-I used EBO9-I Not Not used used EB10-I External EB11-I control Zero command Zeros EB12-I Sense Pairs of command signals EB13-I Zeros Data Data Address Data used for in specific EB14-I Data interrupts Zeros out EB15-I See note 3 Zero __________________________________________________________________________ NOTES: 1. Phase 1 is device or memory selection. 2. Phase 2 is the data transmission. 3. For extended external control, control and data lines are the same as external control except EB11-I is zero and EB15-I is one. *IUAX interlock; used in address decoding.

Table VII summarizes the previously discussed E bus and I/O control signals.

An I/O instruction is not transmitted intact over the E bus. The function code (bits zero to 8) of the instruction are transmitted unchanged. Bits 9 to 15 are decoded in the CPU to generate the configuration of EB11 through EB15 required by the specified operation onto the bus.

INTERRUPT-INITIATED I/O

The computer system includes an interrupt capability whereby the device, on a priority basis, may request execution of an instruction (or a series of instructions) independent of the program in progress. During an interrupt, the computer is directed to a memory address specified by the interrupting device and executes the instruction at that address. Normally, the instruction at the interrupt address results in the processing of an I/O service subroutine. The computer then returns to the original program through an appropriate instruction at the conclusion of the interrupt subroutine. The PIM supplies an addressing capability for those peripheral controllers which do not have the capability of generating an interrupt because of their incapability of providing the necessary memory address. This implements an external interrupt system within the computer interrupt system. A peripheral controller connected to a PIM directs and interrupts requests to the PIM which places the appropriate interrupt address on the I/O bus.

CYCLE-STEALING I/O

Direct-memory-access (DMA), cycle-stealing I/O operations are implemented by the BIC's. Cycle-stealing I/O combines the features of program-controlled and interrupt-initiated I/O. This mode of operation enables the peripherals on the I/O bus to transfer data to or from the computer memory while the processing of the stored program is temporary halted. The DMA requests differ from interrupt requests in the following ways:

a. Interrupt requests direct the computer to the address of a subroutine, whereas the DMA requests require the computer to transfer data to or from memory. The data to be transferred is placed on the E bus after the memory address has been transmitted.

b. The subroutine specified by an interrupt request returns the computer to the main program, whereas DMA request operations repeatedly halt the program while one word of data is transferred, then automatically returns control to the stored program. DMA requests do not disturb the contents of the computer operation registers thereby enabling the CPU to perform other operations during data transfers. DMA operations are initiated by the stored program or by such DMA requests from a peripheral controller under the control of the BIC. A BIC service subroutine establishes the initial and final addresses for the transfer, identifies the peripheral controller, and initializes both the selected controller and the BIC.

When the BIC senses that the peripheral controller is ready to transmit or accept data, it requests a DMA, and after receiving an acknowledgment from the computer, places the initial memory address on the E bus and increments the initial address buffer by one. During the transfer of the data word, the BIC senses the state of the peripheral controller. When more data are ready for transfer, the sequence is repeated until the initial address buffer contents equal the final address. The BIC then directs the computer back to the stored program.

COMPUTER INTERFACE

TOP OF FORM CONTROLLER

The COMPURITE I printing system has the capability of registering printing from the ink jet nozzles in accordance with different speeds of the web ranging from a seven hundred ft/min. to substantially zero ft/min. It is necessary to vary the time of release of the ink droplets so that they will be properly registered on the web at different web speeds.

In printing using ink jet nozzles, a fixed period of time elapses between the emission of the ink drops from the nozzle jets and contact of the drops with the web. It may be assumed that the spacing between the nozzle and the web and the velocity of the ink droplets emitted from the ink jet nozzles are substantially constant. The spacing between an ink jet nozzle and the web is illustrated in FIG. 15. The period of time for transition of the ink droplets from the nozzles to the moving web is short, something in the order of a few milliseconds. At high press speeds the web movement during droplet transition time is substantial and may be as much as perhaps an inch; while at low press speeds the actual movement is negligible. It is therefore quite apparent that the initiation of ink drop emission from the jet nozzles is a critical factor in ensuring contact at the proper position on the web regardless of its speed so as to obtain precise registration of the ink-jet printing at all web speeds.

The theory underlying the determination of ink droplet release may be briefly explained as follows prior to the detailed explanation of the circuitry for correcting the top form pulse in accordance with the web speed as is illustrated in FIGS. 5A, 5B. First, a convenient known number of pulses per inch of web travel is selected; in the embodiment described herein 120 pulses per inch is used. These web speed variable clock pulses are provided to a first counter which continuously counts pulses at a rate directly proportional to web speed. A second counter, driven by a free-running stable oscillator, operates as a control for the first counter to determine a fixed counting period for the first counter. The first counter is then reset to zero and initiates counting in a cyclic manner for successive fixed counting periods. Thus, the number of pulses counted by the first counter will be directly representative of the speed of the moving web and is continuously updated for every cycle of the counter operation. The counting period is determined to be short enough so that the interval thereof is shorter than the time in which the moving web can appreciably change its speed. One of the factors in considering the change in web speed is the inertia of the press which is considerable and thus the web speed cannot change radically in a short period of time. Another factor is the accuracy of the press drive mechanism and the circuitry described herein will also correct for errors in the speed of the press drive mechanism.

The data per count determined by the first two counters is then translated into a proper line control signal for discharging the ink droplet toward the web to ensure their proper contact at the desired points on the web. This translation is accomplished by a third counter, the output of which is provided to digital decoding logic circuitry which recognized a given number of pulses only, for example, the calculated maximum number of inches the web travels during drop flight multiplied by the number of pulses per inch of web travel counted by the first counter. Such a calculation results in a maximum number of pulses that can occur during droplet flight.

Circuitry is also provided to modify the time of droplet release in accordance with the desired form depth thereby adjusting the droplet release to register with the printing cylinder. This top of form circuitry will also be described in detail hereinafter. However, the top of form circuitry provides a pulse to initialize the counting of the third counter up to a preset maximum count. The web speed data obtained from the first two counters is used to preset the third counter at an initial value directly proportional to the speed of the web. The third counter then counts beginning with the initialization pulse, from the initial value, and counts the web speed dependent clock pulses until it reaches the reset maximum count and at that time initiates a control signal used for determining the actuation of ink droplets from the ink jet nozzles.

Assuming that the first counter is allowed to count for 12.5 milliseconds and further assuming that there are 120 pulses per inch of web travel and that the web speed is 700 feet per minute; then the first counter will count a number of pulses determined by the following formula during the aforesaid counting period:

700 ft./min. = 140 inches/sec. 140 inches/sec. .times. 120 pulses/inch .times. 12.5 ms. .times. 1 sec./1000 ms. = 2,100 pulses

From a knowledge of the ink droplet velocity and the spacing between the ink nozzle and the web, it can be calculated that at the maximum web speed of, for example, 700 feet per minute, it is necessary to release the ink droplets 7/12 inches before the desired printing point on the web is actually aligned with the nozzle jet. This calculation can be confirmed by an empirical determination by actually measuring the displacement of the ink droplets at a web speed of 700 feet per minute under the assumed fixed parameters mentioned previously. It is therefore possible to determine from the aforesaid information, namely the 120 pulses per inch of web travel and the seven-twelfths of an inch displacement of the ink droplets, the number of pulses to which the aforesaid third counter must count to release the ink droplets at the proper time with a web speed of 700 feet per minute. The calculation is made as follows:

Number of pulses = 7/12 inch .times. 120 pulses/inch = 70 pulses

In the embodiment of the system described herein, an optical encoder is so positioned with respect to the plate cylinder that it emits top of form pulses seven-twelfths of an inch prior to the actual mechanical top of form position. This is illustrated in FIGS. 3 and 15. From the previous description it is known that when the web is travelling at 700 feet per minute the ink droplet from a nozzle must be released seven-twelfths of an inch before the desired point on the web actually is aligned with the nozzle. Thus, for maximum web speed the third counter is initially preset with that pulse count which corresponds to the maximum web speed (namely, 70 pulses in the above example) thereby providing no delay in the release of the ink droplet. From the foregoing description it is apparent that by appropriately presetting the third counter, the time of droplet release can be determined for any web speed. With reference to FIG. 13 the distance Y from the encoder top of form position for web speeds less than 700 ft./min. is determined as follows: ##EQU1##

Further from the above discussion the number of Y pulses that must be initially preset into the third counter is detemined as follows: ##EQU2##

U.S. patent application Ser. No. 322,534, filed Jan. 10, 1973 by the same inventor, is directed to the aforedescribed counter circuitry for generating correction pulses in accordance with different web speed movement and is incorporated herein for the purpose of explaining the operation of such speed correction circuitry.

The COMPURITE I system also enables the ink jet printing to be registered in accordance with the form depth (i.e., the size of the form on the print cylinder). The printing plate cylinder is illustrated in FIGS. 3 and 13. Plate cylinders are of different sizes and have different circumferences. For the purposes of the present description, it is assumed that the press cylinder is seventeen inches in circumference. A common size form is, for example, an eight and one-half inch form (full development) and represents a form depth of one. A form depth of two may be represented by an eight and one-half inch form placed on separate halves of the plate cylinder, thereby every revolution of the plate cylinder would print two forms. A form depth of three would represent a division of the plate cylinder into thirds; a form depth of four would represent a division of the plate cylinder into fourths, etc. The form depths are illustrated in FIG. 15. As previously mentioned, the Top of Form Controller provides a pulse to initialize the counting of the aforesaid third counter to take into account the different form depths so that the ink jet printing may be registered on different sized forms.

The Top of Form Controller requires timing data to perform the aforedescribed functions. With reference to FIGS. 3 and 13, an electrical top of form (ETOF) pulse which is displaced from the mechanical top of form on plate cylinder 40, is provided for every revolution of the plate cylinder by a suitable transducer, such as slit 41 forming part of an optical encoder. Additional timing pulses are provided by other transducer means, such as slits 42 forming part of another optical encoder. For the purpose of the embodiment described herein, plate cylinder 40 includes 2500 equally spaced slits 42 around the periphery of plate cylinder 40, thereby generating 2500 pulses for every revolution of the plate cylinder. Finally, clock pulses are generated in dependence upon the speed of the moving web. For the purposes of the following description, the web speed dependent clock rate is set at 120 pulses per inch of web movement. Such pulses can be generated in any of a number of ways known to those skilled in the art. For example, the web speed may be taken directly from a gear train on the printing press drive mechanism and formed into pulses by a suitable electrical transducer. The structure for generating the aforementioned electrical top of form pulse, the 2500 pulses per revolution of the print cylinder as well as the 120 pulses per inch of web movement are well known to those skilled in the art so that further elaboration on their respective structures is considered to be unnecessary for the purposes of the present description.

DETAILED DESCRIPTION TOP OF FORM CONTROLLER

The following is a description of the top of form controller which is illustrated in FIGS. 5A and 5B. The ETOF pulse from the optical encoder associated with plate cylinder 40 is provided at terminal 60. The ETOF pulses are used as an initialized pulse for the speed correction counters and as a clear pulse for the form depth counters. It is passed through OR gate 62 (4 common input AND gate), OR gate 64 (2 common input NAND), and inverters 66, 68 comprising a Schmitt trigger. The initialization pulses, generated by circuitry to be described hereinafter, to initiate operation of the Top of Form Controller circuitry are provided by computer command SYRT through NOR gate 70. ETOF pulses at terminal 60 along with the selected outputs of number decoding circuitry (to be described hereinafter) are controlled via the top of form (TOF) switches 1, 2, 3, 4 illustrated at the bottom of FIG. 5A and which are operator selectable. The ETOF is passed to a contact of TOF switch 1 through NAND gate 72; to TOF switch 2 via inverter 74, NOR gate 76 and NAND gate 78; to TOF switch 3 through inverter 74, four-input NOR gate 70 and NAND gate 82; and finally to TOF switch 4 via inverter 74, four-input NOR gate 84 and NAND gate 86.

The plate cylinder revolution (PCR) pulses are input through terminal 88 to provide counter clock pulses via OR gate 90 (4 common input NAND), NOR gate 92 (2 common input NAND) comprising a Schmitt trigger, and inverters 94, 96 to the clock pulse inputs of serially connected binary counters 98, 100, 102. The outputs of counters 98, 100, 102 are decoded by number decoding circuitry which comprises the following components and operates in the following manner.

Selected outputs from binary counters 98, 100, 102 are inverted by inverters 104 and those outputs, along with other selected outputs from binary counters 98, 100, 102 are provided as inputs to number decoding circuits 106, 108, 110, 112 and 114. The inputs to number decoder circuit 106 are such that it decodes the number 1250; the input to number decoder circuit 108 is selected so that it decodes the number 833; and the inputs to number decoder circuits 110, 112 and 114 are also suitably selected to respectively decode the numbers 1666, 625 and 1875. Because the print cylinder is divided into 2500 pulses, it is readily apparent that decoders 106 to 114 respectively decode pulses representing 1/2, 7/8, 2/3, 1/4and 3/4 of the circumference of the print cylinder. The outputs of number decoders 106, 108, 110, 112 and 114 are respectively input to NOR gates 115, 116, 117, 118 and 119. The output of NOR gate 115 (representing 1250 pulses) is fed as an input to NOR gates 76 and 84. The output of NOR gate 116 (representing a pulse count of 833) is fed as an input to NOR gate 80. The output of NOR gate 117 (representing a count of 1666) is fed as an input to NOR gate 80. The output of NOR gate 118 (representing a pulse count of 625) is fed as an input to NOR gate 84. Finally, the output of NOR gate 119 (representing the pulse count of 1875) is fed as an input to NOR gate 84.

From the foregoing description, it is readily apparent that the outputs of NOR gates 72, 78, 82 and 86 represent pulse trains respectively representing form depths of 1, 2, 3 and 4. The respective pulse train outputs from TOF switches 1, 2, 3 and 4 are inverted by inverter 116 and used for control functions which will be described more fully hereinafter.

The circuitry comprising the aforementioned number decoding circuitry including inverters 104 and the connection of the binary outputs of binary counters 98, 100 and 102 to perform the necessary number decoding is so well known to the art that a detailed circuit schematic is not considered necessary for the purposes of the present invention as one having skill in the art will be able to provide suitable number decoding circuitry to perform the known decoding functions specifically set forth above.

In order to properly set counters 98, 100 and 102 so as to establish the correct phasing when a form depth of two is selected, it is necessary to provide the computer SYRT pulse from NOR gate 70 to phase control flip-flop 118, thereby eliminating the possibility of initiating printing on the second half of the plate cylinder. The SYRT Command Pulse clears flip-flop 118 and the ETOF pulse switches flip-flop 118 which then clears counters 98, 100, 102 by the output of AND gate 120. The other input to AND gate 120 is the SYRT pulse or the ETOF pulse which are respectively input via inverters 122 and 74 to respective inputs of NOR gate 124.

The SYRT computer command as well as other data and control signals are input to initialization circuit 130 from the computer in the following manner. The Top of Form Controller is addressed by the computer using the IUAX control signal and the first six bits, namely bits E0 to E5 of the computer E bus. The aforementioned address bits are respectively provided to NOR gates 132, 134, the respective outputs of which are fed, along with control signal IAUX to three-input NAND gate 136. The output of NAND gate 136 is inverted by inverter 138 and provides one input to four-input NAND gate 140. The other three inputs to NAND gate 140 are (external control commands) (EXC) fed from the computer on the computer data bus via bits EB6, EB7 and EB8. The output of NAND gate 140, along with bit EB11 and control signal FRYX from the computer are fed as inputs to NOR gate 142, the output of which is input to NOR gate 70, along with computer control signal, SYRT to provide initialization of the form depth circuitry and the circuitry for correcting the ETOF pulse (modified by the form depth circuitry) to be described hereinbelow.

The Interface clock pulses CP are generated by clock generator 150. A transducer input of 120 pulses/inch is provided at terminal 152 and fed to OR gate 154 (four commmonly connected input AND), NAND gate 156 comprising a Schmitt trigger and inverters 158, 160. In order to avoid confusion in the Figures representing the logic circuitry of the Interface, the clock pulses have been designated as CP throughout the interface schematics.

The following is a detailed description of the aforementioned counter circuitry for generating corrected top of form (CTOF) pulses taken in conjunction with FIGS. 5A, 5B. The CP pulses are fed to the clock pulse inputs of flip-flops 162, 164, 166 in divide-by-five circuit 160. The Q outputs of flip-flops 162, 164 are respectively input to OR gates 166, 168 and the outputs of flip-flop 166. The Q output of flip-flop 162 controls flip-flop 164. The Q output of flip-flop 166 is connected to the J input of flip-flop 162. The Q output of flip-flop 166 represents one-fifth of the CP input to divide-by-five circuit 160. Flip-flops 162, 164 and 166 are re-set by the SYRT Command.

The output of flip-flop 166 is input to the CP input of binary counter 168 which is part of the previously mentioned first counter 169 illustrated in FIG. 3B. The previously mentioned second counter 171 comprises binary counters 170, 172, which cyclically count pulses from ten KHz oscillator 174. This provides a 12.5 millisecond period for gating the divided pulses from flip-flop 166 to first counter 169 in the following manner. Every 12.5 milliseconds, the output of binary counters 170, 172, inverter 176, NAND gate 178, inverter 180, NAND gate 182, and inverter 184 produces a pulse output to gate 182. NAND gate 182 is also controlled by the form depth modified ETOF pulse from the TOF switches previously described. First counter 169 is re-set by a pulse output generated by NAND gate 186 and NAND gate 188. The other input to NAND gate 188 is the command SYRT. The inputs to NAND gates 178 and 186 are properly selected from inverter 176 and the binary outputs of Binary Counters 170, 172 so NAND gates 178 and 186 provide a pulse output every 12.5 and 12.7 ms., respectively. As previously stated, such number decoding circuitry is well known to those skilled in the art. 12.7 milliseconds is convenient because binary counters 170, 172 count to 128 and then are recycled. This enables the necessary time delay for resetting first counter 169 and second counter 171.

The final counter stage of counter 168 is coupled to the CP input of counter 188. The binary counts stored in binary counters 168, 188 of first counter 169 are strobed into quad latches 190, 192 by the pulse output of inverter 184 every 12.5 ms. The web speed information stored in quad latches 190, 192 is loaded into binary counters 194, 196 of third counter 197 through the same pulse every 12.5 ms. Thus, binary counters 194, 196 are preset with the web speed data every 12.5 milliseconds.

The web speed CP are gated to increment binary counters 194, 196 by means of NAND gate 198 (FIG. 5A) which is controlled by the Q output of flip-flop 200 which receives form depth modified ETOF pulses on line 201 from the previously described TOF switches. When binary counters 194, 196 have attained a maximum preset count value, a pulse is emitted from NAND gate 202. The maximum preset value is that number of pulses to provide proper ink droplet release at maximum web speed. In the previously described example, that pulse count is 70 pulses. That maximum preset count is determined by number decoding circuitry comprising Inverter 204, which receives selected inputs from binary counters 194, 196 and NAND gate 202 which receives the necessary inputs from inverter 204 and binary counters 194, 196. The pulse output from NAND gate 202 represents a speed corrected top of form pulse (CTOF) which is used in the Interface as a basic timing pulse to generate STR1 and STR2 character printing control signals as well as other control signals to be described more fully hereinafter. The binary output 64 from counter 196 is used to switch flip-flop 200 (FIG. 5A) to stop the CP input to third counter 197.

HEAD CONTROLLERS -- COMMON ADDRESS CONTROL CIRCUITRY

The Compurite I system requires external control commands from the computer to disable or enable the Head Controllers as well as to stop or start the phasing of the ink jet nozzles. The external control commands DISABLE, ENABLE, STOP PHASING and START PHASING, are provided to the Interface in the following manner with the circuitry illustrated in FIG. 6. The head controller device address is decoded by NOR gates 202, 204 and NAND gate 206. Each of the commands DISABLE, ENABLE, STOP PHASING and START PHASING, is represented by a specific code 0, 1, 2 and 3. The device address (D/A) at the output of NAND gate 206 enables binary-to-decimal decoder 208 thereby allowing the EXC command bits from the computer bus to place a code 0, 1, 2 or 3 into decoder 208. The respective codes 0, 1, 2, 3 are respectively fed to inverters 210, 212, 214 and 216 and the outputs thereof are in turn respectively fed to NAND gates 218, 220, 222 and 224. NAND gates 218 to 224 are enabled by a pulse from NAND gate 226 via inverter 228. The input to NAND gate 226 comprises computer control signal FRYX and data from data bus EB11. Thus, the respective external computer commands DISABLE, ENABLE, STOP PHASING and START PHASING appear as respective outputs from NAND gates 218, 220, 222 and 224 when the computer address signal IAUX is received from the computer along with control signal FRYX. The symbols D and E respectively represent the DISABLE and ENABLE signals previously described and the symbols in FIG. 6 are consistent with their use throughout the Interface.

The Head Controllers (to be described more fully hereinafter) are initialized by the ENABLE signal E which is connected to the clock pulse input of enable control flip-flop 236. Flip-flop 236 is set by the output of AND gate 230 which is responsive to the computer control signal SYRT and DISABLE signal D. The Q output of flip-flop 236 is ENABLE signal E1 which is used to enable specific circuitry within the Interface as will be more fully described hereinafter.

The device address signal (D/A) is provided as an output via inverter 234 to provide a control function for the Master Head Controller which is described more fully hereinafter.

The STOP PHASING and START PHASING signals are provided to the Master Head Controller (FIG. 7) and Head Controllers (2, 3, 4 and 5) (FIG. 8) and their respective functions will be described more fully hereinafter.

The requirements for the STOP PHASING and START PHASING commands will become more clear following the description of the nozzle electronics. However, briefly, prior to actual printing the operator determines that the program is running properly and goes through a check list of questions presented by the computer via the CRT display and operator control as previously described in the description of the Computer. The operator responds to the computer inquiries to provide the necessary information to the computer to complete its program. During this process of establishing the computer program, the software automatically cycles the nozzles through a start phasing and stop phasing operation. That control function and the structure for carrying out that control function will be described more fully hereinafter. The STOP and START PHASING commands comprise a test of the nozzles to make sure that they are operating properly. The computer interrogates the nozzle electronics to actuate a sensor device in the collector of each of the nozzles and if the phasing in each of the nozzles is correct, the nozzle electronics provides the computer with an indication thereof to let the computer know that the nozzles are ready for printing.

NOZZLE SENSING -- SERX RESPONSE

The nozzle sensing is carried out through the Interface in the following manner with reference to FIG. 10. The print ready signal (PRT-RDY) is provided from the nozzle electronics through inverter 240 as an input to NAND gate 242. Because there are 15 nozzles in the system described herein, there are 15 PRT-RDY lines provided to each of the respective nozzles. However, for the purposes of the following description only one of the lines is illustrated and described. A computer code is provided on computer buses EB6, EB7 and EB8 as inputs to NOR gate 244. The remaining input to NAND gate 242 comprises an appropriate code identifying each one of the 15 nozzle controllers. That code is provided by the computer data bus EB3, EB4, EB5 and EB0, EB1, and EB2, the aforementioned signals being respectively input to NOR gates 246, 248.

The address decoder further comprises NAND gate 250 which receives the respective outputs of NOR gates 246, 248 and computer interrupt signal IAUX. The output of NAND gate 250 is inverted by inverter 252 and provided as an input to NAND gate 242 for the respective nozzle to which the sense line is to be directed. This enables the computer to sense the condition of the nozzle to determine if its phasing is correct. If the phasing signal is proper the computer will execute a command to the nozzle electronics stop-phasing of the nozzle. This command is necessary as it is impossible to use the ink jet nozzles for printing while they are being phased. If a phase error is detected in any one of the fifteen nozzles, the computer will identify it via the aforementioned sense line. If such a phase error is detected on one or more of the nozzles the computer will provide an OPERATOR ALERT MESSAGE as described in THE COMPUTER HARDWARE, SOFTWARE, FUNCTIONS AND OPERATIONS above. The operator is thereby made aware of the error and may shutdown or suspend the COMPURITE I system to check the nozzles.

MASTER HEAD CONTROLLER

The previously described enable/disable external computer command may be used to enable and disable the Interface during those times when, for example, the press may be running but is not desired to print anything as the press operator is setting up or other operations are being performed. In such instances the computer will disable the print Head Controllers. The last thing that the computer does before printing is initiated is to enable all of the controllers. The Interface includes a Master Head Controller, which controls the first nozzle head in a print unit, one of such controller circuits being illustrated in FIG. 7 for the purpose of this description. The Master Head Controllers for print units 2 and 3 are similar to that which is illustrated in FIG. 7.

The device address (D/A), previously described with respect to FIG. 6, is inverted by inverter 234 (FIG. 6) and provided as one of the inputs to four-input NAND gate 260. The computer sets NAND gate 260 with control signal FRYX, and data line EB14. The outputs from NAND gate 260 set flip-flop 262 and that flip-flop is switched by the computer signal DRYX to condition 12 bit counter 264 (comprising three four-bit serially connected counters 266, 268 and 270) via a LOAD pulse from NAND gate 272 which is conditioned by the Q output of flip-flop 262 and the computer signal DRYX. A Heading Distance count from the computer is then loaded into counter 264 via computer data bus lines EB0 to EB11. The previously described CTOF pulse is gated by AND gate 274 (the other input of which is appropriately set by the output of Zero Decoder 306, to be described hereinafter) through inverter 276 to toggle flip-flop 278. The Q output of flip-flop 278, along with the web movement CP is input to NAND gate 280 to begin decrementing counter 264 from the Heading Distance count stored therein from the computer.

It is necessary to provide the nozzle electronics with a print request signal sometime prior to the actual initiation of printing to enable the high voltages for droplet charging to be brought up, for example. This print request signal is provided to the nozzle electronics 240 pulses, or two inches before the desired point of printing on the web has reached the nozzles. Decoder 282 decodes the octal number 360, which is equivalent to 240 decimal, by means of octal-to-decimal decoding logic comprising NOR gates 284, 286 and 288. The inputs to NOR gate 284 are taken from counter 266 as illustrated in FIG. 10. The inputs to NOR gates 286 and 288 are taken from the output of counter 268 as indicated in FIG. 7. Inverters 290, 292, 294 and 296 provide the proper signal inversion for the inputs to NOR gates 286 and 288 as indicated in the Figure. The output of NOR gate 284 along with the outputs of NOR gates 286 and 288 are input to decoder 282. The output of decoder 282 along with the computer command STOP PHASING are input to AND gate 298. An end of message signal (EOMS), the generation of which will be described hereinafter, along with the computer command START PHASING are input to AND gate 300 and the output thereof is fed as an input to AND gate 302 along with enable pulse E1. The output of AND gate 302 sets flip-flop 304 and the output of AND gate 298 switches flip-flop 304 to provide the print request signal to the nozzle electronics two inches, or 240 pulses of web movement before the point of desired printing from the first nozzle is to be initiated on the web. The print request signal to the nozzle electronics is a command to get ready to print to stop the phasing mode and enter the printing mode. Two inches is selected as it provides the necessary time for the nozzle electronics to bring up the high voltage levels and to discontinue phasing taking into consideration a maximum web speed of 700 feet per minute.

Simultaneously with the previously described decoding operation, counter 264 continues to decrement by means of web speed CP provided through NAND gate 280. Zero decoder 306 determines the zero count in counter 264 through decoding logic comprising NOR gates 308, 310 and 312 which are connected to the respective outputs of counters 266, 268 and 270 as illustrated in FIG. 7. The output from zero decoder 306 represents an artificial strobe one pulse (ASTR1) which initiates the Head Controllers 2, 3, 4 and 5 of that print unit associated with the Master Head Controller of that print unit. ASTR1 is input to NAND gate 314. ASTR1 is also input to flip-flop 316 and to divide-by-twelve circuit 318 through inverter 320. Flip-flop 316 is set by AND gate 444 (described hereinafter) and is toggled by ASTR1 and the Q output thereof along with web speed CP are provided to AND gate 322 thereby allowing the CP to enter divide-by-twelve counter 318. The output of counter 318 is decoded by NAND gates 324, 326 and 328. There are ten characters per inch in each line of print and with the 120 clock pulses per inch of web movement there are twelve pulses per character. Reference to FIG. 14 illustrates the relationship of the character strobe 1 (STR1) and stroke strobe 2 (STR2) pulses. For every strobe 1 pulse there are five strobe two pulses. There are therefore a total of six strobe 1 and strobe 5 pulses for each character. The output of NAND gate 328 is inverted by inverter 330 and input to NAND gate 332 along with the signal .DELTA. (the generation of which will be described more fully hereinafter. The output of NAND gate 332 along with ASTR1 provides the necessary STR1 pulses at the output of NAND gate 314 to generate each character from nozzle 1 controlled by the Master Head Controller in a print unit. The STR2 pulses are generated at the output of NAND gate 326 and consist of five pulses each respectively representing controls to determine the X1, X2, X3, X4 and X5 columns in the 5 .times. 7 Character matrix of the nozzle electronics.

The aforementioned operations of the Master Head Controller for each print unit cyclically operates in the aforementioned manner. The computer will provide the necessary Heading Distance to counters 264 should there be a change in that information, as would be required to print at different locations of a form on print cylinder 40.

HEAD CONTROLLERS (2, 3, 4, 5)

The following is a description of the head controllers for print heads 2, 3, 4 and 5 of each print unit. For the purposes of this description only one such Head Controller is described with reference to FIG. 8. There are four such Head Controllers in each print unit and twelve of these Head Controllers in the three printing unit COMPURITE I system. Each of head controllers 2, 3, 4 and 5 of each print unit generates ASTR1, STR1 and STR2 pulses. Some of the circuitry in head controllers 2, 3, 4 and 5 is similar to the Master Head Controller (FIG. 7) and therefore is denoted by the same numeral designation. In this regard, the web movement CP are input to AND gate 340 which is set by an input from the Q output of flip-flop 342 which is in turn set by the output of AND gate 344 and switched by the CP input. AND gate 344 receives an Enable E.sub.1 input along with an EOM signal (the generation of which will be described hereinafter). The setting of AND gate 340 enables divide-by-twelve counter 318 to divide CP. Decoding logic comprising NAND gates 324, 326, 328, inverter 338, NAND gate 332, and NAND gate 314 generator the STR1 and STR2 strobe pulses in a similar manner to that previously described with respect to the generation of those respective print control pulses generated by the Master Head Controller. The previously mentioned .DELTA. signal generated in association with the end of message circuitry for the Master Head Controller is fed as one input to NAND gate 314 to stop the STR1 pulse generation. The STR2 pulses are provided from the output of NAND gate 326 in a manner similar to that previously described for the generation of the STR2 pulses from the Master Head Controller.

The primary difference between Head Controllers 2, 3, 4 and 5 and the Master Head Controller for a given print unit is the counter circuitry. Head Controllers 2, 3, 4 and 5 each include a counter 350 comprising serially connected binary counters 352, 354 and 356. There is a fixed spatial relationship between each of the nozzles in each print unit. For the purposes of this description the spacing between each of the nozzles is 21/2 inches. (see FIG. 2). 21/2 inches times 120 pulses per inch of web travel results in 300 pulses which is the pulse nozzle lag between respective adjacent nozzles in a print unit. Thus, the STR1 and STR2 pulses of each respective Head Controller 2, 3, 4 and 5 for a given print unit can be generated by counting to 300 and initiating that counting with the ASTR1 of the immediately adjacent previous head. Thus, for Head Controller 2, the ASTR1 of the Master Head Controller of that particular print unit is input to AND gate 358. The other input to AND gate 358 is set positive because NAND gate 274 has not yet been gated and thereby flip-flop 360 is toggled by the output of AND gate 358 through inverter 362. The Q output of flip-flop 360 clears and initiates the counting of CP by counters 352, 354, 356. Counters 352, 354 and 356 increment to a binary octal count of 454, which is a decimal count of 300. The output of counters 352, 354 and 356 is converted from binary octal to decimal by well-known octal-to-decimal converting circuitry represented illustratively by NAND gates 358, 360 and 362, inverters 364, 366 and 368, and inverter 370. The actual connections of the decoding circuitry are not shown to simplify the drawing as such number decoding circuitry is well known to those skilled in the art as has been previously stated. The output of NAND gate 274 represents the ASTR1 pulse of the particular Head Controller 2, 3, 4 or 5 and is inverted by inverter 374 to reset divide-by-twelve counter 318. The ASTR1 pulse from each of Head Controllers 2, 3, 4 and 5 is output from a NOR gate 376. The ASTR1 pulse of Head Controller 2 is fed as an input to Head Controller 3 whereupon the same operation as previously described takes place. In similar fashion, the ASTR1, STR1 and STR2 pulses of Head Controllers 3, 4 and 5 are generated.

The print request from head controllers 2, 3, 4 and 5 of a given print unit must also be generated in advance of the STR1 and STR2 pulses in a manner similar to that previously described with respect to the Master Head Controller. In this instance the binary octal-to-decimal conversion is provided by NAND gates 378, 380, 382, inverter 372 and inverters 384, 386 and 388. This number decoding circuitry decodes the octal number 74 which is equivalent to 60 decimal. The output of NAND gate 390 is fed as an input to AND gate 292 along with the STOP PHASING command to control flip-flop 294 in the same manner as flip-flop 304 in the Master Head Controller to generate the print request output from each respective one of Head Controllers 2, 3, 4 and 5. Flip-flop 294 is set by the output of AND gate 296 which is conditioned by the command START PHASING and an EOM signal (to be described below).

HEAD CONTROLLERS COMMON -- END OF MESSAGE

As has been previously stated, each nozzle prints a line consisting of thirty-eight characters (including spaces) and in order to terminate the printing from each nozzle it is necessary to keep track of the number of characters that have been printed by each nozzle. The circuit illustrated in FIG. 9 provides this function for each of the nozzle heads. Because the circuitry is similar, only one such circuit will be described for the purpose of illustrating the manner in which the characters are counted.

The previously described STR2 pulses are fed to the clock pulse input of flip-flop 400. The K input is grounded and the J input is connected to + five volts. The enable E pulse along with the Q output of flip-flop 400 are input to NAND gate 401, the output of which is connected to the clock pulse input of flip-flop 402. The J input and the K input of flip-flop 402 are each connected to + five volts. The clock pulses to flip-flop 402 cause it to toggle providing outputs at its Q and Q terminals. The Q output of flip-flop 402 along with the Q output of flip-flop 400 and the STR2 pulses from the associated Head Controller are input to NAND gate 404. The output of NAND gate 404 and the CTOF pulse from the Top of Form Controller are input to NAND gate 406 to provide a register strobe shift pulse the purpose of which will be described hereinafter with the description of the Nozzle Controller circuitry of FIG. 10. Additionally, the Q and Q outputs of flip-flop 402 are also provided to terminals 409 and 411, respectively, to serve as additional register strobe pulses, the purpose of which will also be described with the circuitry of FIG. 10.

Binary counters 408, 410 count the number of characters printed by each nozzle in the following manner. Prior to a detailed discussion of the counting operation, it is necessary to note that two characters are stored in each storage buffer of the Nozzle Controller for each nozzle with the computer initialization of the system. The data for two additional characters are transmitted from the computer to the storage buffers of each Nozzle Controller with the previously described ETOF pulse. ETOF also shifts the two previously stored characters from the storage buffers of each Nozzle Controller to the Print Buffers of each Nozzle Controller. Thus, prior to an actual print operation of each nozzle, there are four characters stored in each of the Nozzle Controllers. To terminate the character printing from each nozzle it is therefore necessary to count the aforementioned two character shift operations seventeen times. In the case of the head controller for Head Controller 1 of each print unit, the CTOF pulse is transmitted to one input of AND gate 412. The other input of AND gate 412 is the enable E1 pulse. The output of AND gate 412 is input to the clear input of flip-flop 414. The Q output of flip-flop 414 is connected as one input to NAND gate 416. The other input of NAND gate 416 comprises the toggled output Q of flip-flop 402 which is inverted by inverter 418. The output of NAND gate 416 is connected to the clock pulse inputs of counters 408, 410. The counters 408, 410 are binary counters with the respective outputs of counter 408 being 1, 2, 4 and 8; and the respective outputs of counter 410 being 16, 32, 64 and 128. Number decoder 420 is set to decode seventeen STR1 pulses. As has been previously described, there are five STR2 pulses for every STR1 pulse. Therefore, number decoder 420, in order to count the number of characters, is set to decode thirty-four STR1 pulses. The necessary inverter circuitry is represented in FIG. 9 by Inverter 422. Again, the actual connection from the respective outputs of binary counters 408, 410 has not been shown in order to avoid confusion in the drawings. The decoding circuitry and the connections thereto are well known in the art. After number decoder 420 has detected the thirty-fourth STR1 pulse (the seventeenth character shift), its output triggers the clock pulse input of flip-flop 414. This causes the Q and Q outputs of flip-flop 414 to switch. The Q output then closes NAND gate 416 thereby terminating the clock pulse inputs (divided STR2 pulses from Q output of flip-flop 402) to binary counters 408, 410. Additionally, the closing of NAND gate 416 also terminates the generation of Print Data Request Instructions (PDRI) to the PIM of the computer through the chain of NOR gates 424, 426, 428 (two-input common coupled NAND gates) as is indicated in FIG. 9.

Binary counter 430 and its associated circuitry provide two end of message signals which are generated and function in the following manner. In the case of each of the Master Head Controllers, the clock pulse input of counter 430 receives the pulse output from inverter 330 (FIG. 7) which is in the chain of logic circuits generating the STR1 pulses for the Master Head Controller. In the case of Head Controllers 2, 3, 4 and 5, the clock pulse input of counter 430 is the respective outputs of inverter 338 in each of Head Controllers 2, 3, 4 and 5, which were described with respect to FIG. 8. The previously mentioned output of number decoder 420 shifts the Q output of flip-flop 414 which is provided to the clear input of binary counter 430. This enables a respective counter 430 to receive STR1 pulses from each of the respective Master Head Controller and Head Controllers 2, 3, 4 and 5. Inasmuch as there are four characters remaining in each of the storage and print buffers for each of the respective Nozzle Controllers (after 17 character shifts), it is necessary to count four STR1 pulses to terminate the generation of STR1 and STR2 pulses to terminate a line of printing from each nozzle. End of message number decoder 432 detects the count of four in binary counter 430 and number decoding circuitry 434 illustrated in block diagram form provides the necessary inputs to end of message number decoder 432 from the binary outputs 1, 2, 4 and 8 of binary counter 430 to perform this function. Numeral 434 represents the inverter circuitry used in this number decoding operation. The output of end of message number decoder 432 is connencted to the input of NOR gate 436 (a NAND gate with commonly connected inputs) through inverter 438. The output of NOR gate 436 represents an end of message (EOM) signal which is transmitted to the PIM of the computer.

End of message number decoder 440 provides an additional control function which is described hereinafter. Number decoder 440 is connected to the appropriate outputs of binary counter 430 (using inverters 434) to be gated with the third STR1 pulse counted by counter 430. The output of end of message number decoder 440 is connected to the clock pulse input of flip-flop 442. Flip-flop 442 has been reset by an input at its clear input from the ASTR1 signal from its associated respective Master Head Controller or Head Controllers 2, 3, 4, 5 as the case may be. The input to flip-flop 442 through its clock pulse input from end of message number decoder 440 causes the Q output of flip-flop 442 to switch and generate the previously mentioned signal .DELTA. . Signal .DELTA., from each of the fifteen respective Head Controllers common -- End of Message circuitry, is transmitted to the three respective Master Head Controllers and the 12 Head Controllerse 2, 3, 4, 5 in the following manner. In the case of the Master Head Controller, signal .DELTA. is connected as an input to NAND gate 332 in FIG. 7, which then closes that NAND gate to terminate the generation of STR1 pulses. In a similar manner the signal .DELTA. is connected to the input of NAND gate 332 in the respective Head Controllers 2, 3, 4 and 5, previously described with respect to FIG. 8, thereby terminating the STR1 pulses from each of Head Controllers 2, Controllers 4 and 5.

The EOM output from an associated end of message number decoder 432, in the case of the Master Head Controller for each print unit, is connected to the input of AND gate 444 in that Master Head Controller (FIG. 7). The other input of AND gate 444 is enable signal E1. The pulse output from AND gate 444 is connected to the clear input of flip-flop 316 to terminate the operation of divider 318 and the subsequent decoding circuitry, thereby terminating the generation of STR2 pulses (FIG. 7).

In the case of each Head Controller 2, 3, 4 and 5 (FIG. 8), the EOM output of a respective end of message number decoder 432 is fed to the input of AND gate 344, along with the enable E1 signal. The pulse output from AND gate 344 is fed to the clear input of flip-flop 342, thereby terminating the operation of divider 318 and the subsequent logic circuitry illustrated in FIG. 8, to end the generation of STR2 pulses from each Head Controller 2, 3, 4 and 5 of each print unit.

NOZZLE CONTROLLERS -- CODED ALPHA/NUMERIC DATA TO NOZZLE ELECTRONICS

In the COMPURITE I system there are five nozzles per print head and in the embodiment described herein there are three print heads in the system. The nozzle controller circuitry performs the function of receiving the data to be printed from the computer and the transmission of that data to each of the respective nozzles in each of the print heads so that each line of the desired variable information is printed in registered alignment with respect to the form on print cylinder 40. Thus, there are 15 nozzle controllers in the COMPURITE I system as described herein. A typical nozzle controller circuit is illustrated in FIG. 10.

The manner in which the computer addresses each nozzle controller and sets up the sense line to instruct each nozzle to enter its phasing mode and to instruct each nozzle to discontinue its phasing mode has been previously described. Each alpha/numeric character is represented by a seven bit code in the ASCII code format (see Table I, supra). Two characters are entered simultaneously in each nozzle controller. One character is transmitted on the computer bus lines EB0 to EB6 and another character is represented by data on computer E bus line EB8 to EB15. Character data on E bus lines EB0 to EB6 are entered into storage buffers 450, 452. Another character is stored in storage buffers 454, 456. The character information is strobed into storage buffers 450 to 456 by flip-flop 458 which is cleared by the output of NAND gate 460 with the computer signal FRYX, E bus EB14 and the output of the previously described address registers. The computer signal DRYX is supplied to the clock pulse input of flip-flop 458 and the Q output thereof gates the data from data buses EB0 to EB15 into storage buffers 450 to 456. The shift pulse at terminal 407, which is generated by the CTOF pulse from NAND gate 406 (as previously described with respect to FIG. 9) strobes the character information two characters at a time from storage buffers 450 to 456 into respective print buffers 462, 464, 466 and 468 through gate 470, inverter 472 and gate 474.

The character data in print buffers 462 to 468 is alternately strobed out of those buffers in the following manner. The register strobe pulses previously described which appear at terminals 409, 411 of FIG. 9 are applied as respective inputs to gates 476, 478. As previously described, the pulses at terminals 409, 411 represent alternate STR2 pulses from an associated Master Head or Head Controller. Additionally, as previously described with respect to FIG. 9, a PDRI pulse is transmitted to the PIM of the computer to request new character data. This occurs each time the character data is shifted between the storage and the print buffers.

The pulses at terminals 409, 411 from the respective Q and Q outputs of flip-flop 402 in FIG. 9, alternately control a series of AND gates 480, 482, 484, . . . 486, etc. to alternately gate the output character data from print buffers 462, 464 and print buffers 466, 468 through additional AND gates 488, 490, etc.; OR gates 492, 494, 496, etc.; and line drivers 498, 500, 502, 504, 506, 508 and 510 to provide seven bits of information representing each character on data lines L1 to L7. That information on lines L1 to L7 is then provided as an input to the nozzle electronics for generating the necessary control voltages in the charging tunnel of the associated nozzle for each character. It is recognized that not all of the logic from the output of print buffers 462 to 468 and the lines L1 to L7 has been illustrated in the drawings. Only an illustrative number of gates and connections between the outputs of print buffers 462 to 468 and lines L1 to L7 have been shown in order to avoid confusing the schematic. It is understood that one having ordinary skill in the art will recognize the connection of the additional necessary logic gates to the respective outputs of print buffers 462 to 468 to provide the necessary character data on lines L1 to L7. The character data output from each nozzle controller is in ASCII.

In the head controller circuitry described in FIG. 9, the logic circuit 309, the output of which clears flip-flop 400 and which receives the DISABLE D and the output of inverter 330 in the respective Master Head Controller circuit and Head Controller 2, 3, 4, 5 circuits (FIGS. 7 and 8, respectively) ensures the proper status of flip-flop 400. Logic circuit 309 differs for the Master Head Controller and the Head Controllers 2, 3, 4 and 5. Logic circuit 309 for the Master Head Controller is illustrated in FIG. 11A and logic circuit 409 for the Head Controllers 2, 3, 4 and 5 is illustrated in FIG. 11B.

FIG. 14 illustrates the relative appearance of the PRINT REQUEST signal, the PRINT READY signal, the STR1 and STR2 pulses, the status of data lines L1 to L7 and the web movement CP pulses. Inasmuch as the CP is variable with web movement, the aforementioned signals illustrated in FIG. 14 will shift with respect to time; however, the order in which they are generated relative to each other is as illustrated in FIG. 14 for all web or press speeds.

The relationship and the interconnections between the Figures of the above described interface circuitry are illustrated in FIG. 12.

NOZZLE ELECTRONICS

FIG. 15 illustrates, in block diagram format, the essential components of the nozzle electronics and the application of the signal generated by the nozzle electronic circuitry to the various elements of a nozzle which are illustrated at the bottom of FIG. 15. Matrix generator 550 receives the character set in ASCII on data lines L1 to L7 from FIG. 10 of the interface which has been previously described. Matrix generator 550 also receives character generating timing pulses STR1 and STR2 from each of the Master Head Controller and Head Controller 2, 3, 4 and 5 circuits of the Interface. In the COMPURITE I system described herein, because there are 15 nozzles each of which is printing a separate line of alpha/numeric characters, it is necessary to have fifteen matrix generators 550 each respectively receiving individual character data on separate data lines L1 to L7 and character signal timing data STR1 and STR2 from Head Controllers associated with the specific nozzle.

Each matrix generator 550 generates a digital pulse stream wherein each pulse represents one ink droplet. Matrix generator 550 also produces timing pulses, and the aforementioned digital pulse stream and the timing pulses are received by D/A conversion circuit 552 (video generator) which converts the digital pulse stream utilizing the timing pulses into an analog video signal. The output of video generator 552 represents a low level video representation of each of the characters received by the matrix generator 550.

The low level video character data from video generator 552 is input to final amplification circuitry 554 which comprises the following basic components: nozzle driver circuitry, video amplifier circuitry and high voltage deflection circuitry. The nozzle driver circuitry provides the 66 KHz sine wave excitation for exciting a piezoelectric crystal in nozzle 556, the purpose of which will be more fully explained hereinafter. The 66 KHz sine wave sync signal is provided from video generator 552 to the nozzle driver circuitry in final amplification circuitry 554. Video generator 552 transmits the previously described PRT RDY signals and receives the PRT REQ signals described with respect to the Interface.

The video amplifier section of final amplification circuitry 554 amplifies the low level video character data from video generator 552 and its output is provided to charging tunnel 558 whereby the selected ink droplets are given one of seven voltage charges (or no voltage charge) in accordance with the low level video character information generated by video generator 552 from matrix generator 550. The charging of the droplets to produce alpha/numeric characters will be more fully explained with respect to FIG. 16.

The 66 KHz excitation of nozzle 556, along with the pressure of the ink supplied to the nozzle via port 557 from an ink supply (which will be more fully described hereinafter) causes the ink to break up into discrete droplets at a rate of 66,000 per second.

High voltage deflection circuit output of final amplification circuitry 554 is applied to deflection tunnel 560 (which is rotated 90.degree. in FIG. 15 from its actual position with respect to the ink droplets) whereupon each of the ink droplets is deflected a distance directly proportional to the charge received by the ink droplet as it is passed through charging tunnel 558. In the actual nozzle embodiment, the ink droplets are deflected out of the plane of FIG. 15 onto moving web 39. Those ink droplets 559 which did not receive a charge while passing through charging tunnel 558 are not deflected in deflection tunnel 560 and are received by collector 564 where they are returned to the ink system via a vacuum return line 566.

A sensor 568 is mounted within collector 564 to provide detection of the ink droplets during the phase mode of the nozzle. Broadly speaking, it is necessary to sense whether or not the ink drops are occurring with the proper phase so that they assume the proper charge. And if the proper charge it not being applied to the ink droplets, then the phasing of the ink droplets is adjusted by correcting the phase of the 66 KHz vibration signal to the nozzle. The phasing of ink droplets, and the circuitry for performing such phasing and sensing operations, is disclosed, for example, in U.S. Pat. Nos. 3,465,350, 3,465,351 (both issued Sept. 2, 1969) in the name of I. R. Keur et al, and U.S. Pat. No. 3,562,761, issued Feb. 9, 1971 to J. J. Stone et al. The ink droplet phasing techniques and apparatus disclosed in the above U.S. patents are incorporated herein by reference solely for the purpose of providing an understanding of the function and operating of ink droplet phasing as it applies to the COMPURITE I system. However, it is understood that the circuitry for performing ink droplet sensing and phasing does not, in and of itself, form a part of the present invention. The droplet sensing and phasing is performed by a phasing and droplet sensor circuit 570 in FIG. 15, which transmits a phasing signal to video generator 552 whereby the PRT RDY signals can be generated.

It is noted that the jet nozzle orifice has a diameter of 2,000ths of an inch and that the distance between collector 564 and the moving web 39, in the COMPURITE I system described herein is substantially 1/2 inch.

PRINCIPLE OF CHARACTER GENERATION BY INK DROPLET CHARGING

FIGS. 16A to 16G illustrate the principle or theory of operation for generating video signals whereby the 64 alpha/numeric characters of the COMPURITE matrix font (illustrated in FIG. 4) are generated by the nozzle electronics. As previously described with respect to FIG. 15, the amplified video signals representing the charging of voltages defining a particular character are applied to the charging tunnel 558. FIG. 16B shows the relationship of the 35 pulses that are available to produce a given alpha/numeric character within a 5 .times. 7 character matrix. As previously described with respect to the computer COMPURITE Interface, the STR1 pulses are used by the nozzle electronics to indicate each alpha/numeric character in a line of print from each of the 15 nozzles. The STR2 pulses, produced by the respective Master Head Controllers and the respective Head Controllers 2, 3, 4 and 5, are respectively associated with a given column X1, X2, X3, X4, X5 of the 5 .times. 7 character matrix. The rows are respectively identified as Y1, Y2, Y3, Y4, Y6, and Y7 as illustrated in FIG. 16G. Within the time interval of each of the STR2 pulses which define the intervals X1 to X5, there are generated respective voltage levels each representing the row of the matrix Y1 to Y7 as illustrated in FIG. 16A. Thus, if 35 pulses were generated by matrix generator 550 (FIG. 15) there would result in the nozzle printing a complete square inasmuch as there would be charging voltage applied to the charging tunnel 558 for each droplet in the drop stream (as illustrated in FIG. 16C) for each column X1 to X5 of the matrix.

FIGS. 16D, E, F and G illustrate the manner in which the letter E is generated. The matrix generator in the nozzle electronics, in accordance with the STR1 and STR2 pulses and the character data on lines 1 to 7 from the Interface, produces a stream of pulses during the X1 interval to generate successive step voltages corresponding to Y1 to Y7, which voltages are provided by the video amplifier to the charging tunnel. Inasmuch as the droplets passing through the charging tunnel are phased or in synchronism with the pulses, a respective higher charge is placed on each of the seven successive droplets passing through the charging tunnel during the interval X1. Thus, for the column X1, there is printed on the moving web a line of dots where the charge droplets are respectively displaced different distances along an axis transverse to the axis of movement of the web as the droplets pass through the deflection tunnel. In the interval X2, only the first, fourth and seventh pulses in that interval are produced by the matrix generator and results in excitation levels of the video amplifier corresponding to Y1, Y4 and Y7. This pulse generation from the matrix generator is repeated again for the intercals X3 and X4. In the interval X5 only the voltage levels corresponding to Y1 and Y7 are generated by the pulse stream illustrated in FIG. 16E, thereby resulting in only the first and seventh droplets passing through the charging tunnel during that interval being given a charge. The remaining droplets, namely droplets 2 through 6, are not charged and therefore are not deflected as they pass through the deflection tunnel. Consequently, uncharged droplets, regardless in what interval X1 to X5 they occur, are not deflected and pass into collector 564 illustrated in FIG. 15.

INK SYSTEM

FIG. 17 illustrates a side view of print unit 38 illustrating the mechanical structure and relationship of the ink supply and ink vacuum return for a typical print unit. Ink is forced under pressure into ink supply manifold 600 through supply and bleed solenoid assembly 602 which receives ink at ink input 604 from an ink supply (which will be described hereinafter). For purposes of the following description, only one of the ink systems is illustrated and described inasmuch as the ink systems for each of the ink jet nozzles are identical. The ink for jet nozzle 38c enters through a connection 606 to ink supply manifold 600 and passes through manual shutoff valve 608. Before entering nozzle head 610, the pressurized ink is filtered by filter 612 and passes through pipe 614 to nozzle head 610, via connector assembly 616. The ink droplets produced by the vibratory transducer pass through a charging tunnel (not illustrated in FIG. 17) and then past deflection plate 612 and onto moving web 39 or collector 614 in accordance with the droplet charge deflection. As mentioned previously, the uncharged drops are collected by collector 614 and the ink in collector 614 is returned through internal passages through vacuum outlet pipe 616 which is connected to vacuum return manifold 618. The ink collected from each of the collectors in each of the ink jet nozzles is drawn out vacuum return 620.

The ink supply regulator system consists essentially of a dual head pump, two ink reservoirs, two adder solution reservoirs, a vacuum pump, various gauges, tubing, and associated electrical controls. The pump feeds ink to the print heads at approximately 42 PSI, plus or minus one-quarter PSI. The pump draws ink from either or both of the two ink reservoirs using either one or both pump heads. The air in the ink reservoir is evacuated by the vacuum pump. The resulting vacuum is used to draw the return ink away from the print heads into the reservoir. The ink reservoirs are replenished automatically from the adder solution reservoir. The ink system may be provided with suitable low pressure and low vacuum interlocks to avoid ink spillage.

An exemplary embodiment of the ink supply system is illustrated in FIG. 18. Ink reservoir 622 is in a vacuum created by pump 624 through filter 626, ink trap 628, and vacuum line 630 which has port 632 within ink reservoir 622 as illustrated in the Figure. Adder reservoir 634 is at atmospheric pressure and ink from adder reservoir 634 is automatically added to ink reservoir 622 via pipe 636, control solenoid 638 and pipe 640. Solenoid 638 is controlled by a level sensing device (not illustrated) in ink reservoir 622. Ink pump 642 pumps ink out of ink reservoir 622 through valve 644 and filter 646. 625 represents a high vacuum switch which is set at approximately 25 inches HG and 629 represents a minimum vacuum switch set at 5 inches HG. Vacuum gauge 631 is provided to read the vacuum in vacuum line 633.

Ink is pumped from pump 642 through line 648 to pressure regulator 650, which is variable from zero to 60 PSI. Pressure regulator 652 is set at approximately 35 PSI so as only to release ink to the respective nozzles 38a to 38e when the ink in line 648 exceeds 35 PSI. Bypass regulator 654 is provided as an additional means of controlling the ink pressure in line 648. Pressure gauges 656 and 658 are provided at appropriate points in line 648 to read the pressure therein. Pressure gauge 656, for example, will read zero to 100 PSI, and pressure gauge 658 is capable of reading zero to 60 PSI. The ink under regulated pressure of approximately 42 PSI is fed to ink manifold 600, through the previously described supply and bleed solenoid assembly 602 (FIG. 17) and then through manual shutoff valves 608a to 608e.

The ink from collectors 614a to 614 e is respectively returned to vacuum manifold 618 as illustrated in FIG. 18, and the ink at vacuum return 620 is drawn through filter 600 and returned to ink reservoir 622. FIG. 21 represents only one-half of the ink supply system, there is a back-up system which is descriptively indicated at the lower right of FIG. 18 and which is similar to the previously described ink feed regulator system.

The ink used in the COMPURITE I system is a water base, dry-type ink. Its critical characteristic is its viscosity which is normally 1.8 centipoise. The ink must be electrically conductive in order to accept a charge as the ink droplets are passed through the previously described charging tunnel. The electrical conductivity of the ink is not critical as its conductivity can be compensated by varying the charging voltages at the charging tunnel. The ink dries by absorption and not evaporation so as to prevent ink drying the nozzles.

Claims

What is claimed is:

1. A printing system wherein variable alpha/numeric data is printed in registered and aligned relationship with fixed data printed by a master plate cylinder on a moving web at press speeds, comprising:

means for providing coded data representative of said variable data in a selected multiple line message format and for providing command signals;

control means for receiving said coded data and responsive to said command signals for generating character timing signals representing the sequential position of said alpha/numeric data in said multiple line message format, and including means for automatically adjusting said character timing signals to account for different web speeds and variable form depth data, said means for automatically adjusting said character timing signals includes means for generating a top of form pulse for each revolution of said master cylinder, said top of form pulse occurring prior to the mechanical top of form of said master cylinder, means for generating first pulses having a pulse rate dependent on the speed of the web, and means for correcting said top of form pulse in accordance with said first pulses, said means for automatically adjusting said character timing signals being responsive to said corrected top of form pulse; and

means for printing said variable data in response to said character timing signals by the projection of independently controlled ink droplet streams onto said moving web.

2. A printing system as in claim 1 wherein said control means includes means for establishing a number of different master cylinder form depths and said means for automatically adjusting said character timing signals includes switching means for correcting said top of form pulse in accordance with a desired one of said form depths.

3. A printing system as in claim 2 wherein said means for automatically adjusting said character timing signals further includes means for counting pulses including a first counter for counting said first pulses, means for controlling said first counter to count for a fixed period of time and said means for correcting said top of form pulse includes a counter for storing the count in said first counter and counting said first pulses until a predetermined count is reached and generating a signal representing said corrected top of form pulse.

4. A printing system as in claim 3 wherein said means for controlling said first counter comprises a third counter and means for generating second pulses at a fixed rate, said third counter establishing a periodic sampling for the operation of said first counter.

5. A printing system as in claim 3 wherein said control means further includes pulse generating means for generating second pulses having a fixed number of pulses per revolution of said master cylinder and said means for automatically adjusting said character timing signals further includes second counter means for counting said second pulses, number decoding means for determining the number of pulses corresponding to said number of form depths and gate means for gating the number of decoded pulses to said switching means in response to said top of form pulse, said switching means delaying the initiation of said second counter means in accordance with a desired form depth.

6. A printing system as in claim 5 wherein said means for establishing a number of different master cylinder form depths further includes means for inhibiting to establish a correct phasing when a form depth of two is selected.

7. A printing system as in claim 1 wherein said means for printing includes at least one printing unit including a number of ink-jet nozzles mounted in staggered relationship along an axis parallel to the movement of said web and each independently controlling the release of an ink droplet stream, and said control means further includes a master controller and a number of slave controllers for controlling said at least one printing unit, said master controller controls that ink-jet nozzle first confronting selective printing areas on said moving web and said slave controllers each control a selected one of said remaining ink-jet nozzles, said master controller is responsive to said corrected top of form pulse for generating signals controlling the release of ink droplets from the associated ink-jet nozzle and secondary timing signals, one of said slave controllers generating tertiary timing signals controlling the release of ink-droplets from the associated ink-jet nozzles and for controlling another of said slave controllers, whereby said slave controllers generate signals for controlling the release of ink droplets from an associated ink-jet nozzle and additional timing signals for controlling that slave controller associated with a successively displaced one of said ink jet nozzles.

8. A printing system as in claim 7 wherein said means for providing coded data includes buffer and print storage means for storing successive alpha/numeric characters within said multiple line message format and means for generating shift pulses from said corrected top of form pulse to shift data from said buffer register to said print register and to store new data in said buffer register, and said means for printing being responsive to the output from said print register.

9. A printing system as in claim 7 wherein said signals from said master and slave controllers for controlling the release of ink droplets each include primary pulses having a pulse rate determined at least partially by the speed of said moving web and secondary pulses spaced between said primary pulses, said primary pulses denoting successive alpha/numeric characters and said secondary pulses controlling an ink-droplet stream from the associated ink-jet nozzle.

10. A printing system as in claim 9 wherein said master controller includes counting means for receiving heading distance information from said means for providing coded data, means for gating said first pulses to said counting means for decrementing said counting means, and means responsive to the decrementing of said counting means to zero to produce an artificial strobe pulse for initiating the generation of said secondary timing signals.

11. A printing system as in claim 10 wherein said master controller further includes means for dividing said first pulses and first gating means responsive to the output of said dividing means to generate said primary pulses and second gating means responsive to the output of said dividing means for generating said secondary pulses.

12. A printing system as in claim 9 wherein said slave controllers each includes counting means, and means for gating said first pulses to said counting means and means responsive to said counting means attaining a predetermined count representative of said staggered relationship between said ink-jet nozzles for generating an artificial strobe pulse for initiating the generation of said additional timing signals.

13. A printing system as in claim 12 wherein each of said slave controllers further includes means for dividing said first pulses and first gating means responsive to the output of said dividing means to generate said primary pulses and second gating means responsive to the output of said dividing means for generating said seconary pulses.

14. A printing system as in claim 9 wherein said control means further includes means for determining the number of characters printed by each of said ink jet nozzles and being responsive to said primary and secondary pulses from each of said master and slave controllers and wherein said means for providing coded data further includes means for temporarily storing coded data representative of said variable data and responsive to said means for determining the number of characters printed to transmit said coded data to said means for printing.

15. A printing system as in claim 14 wherein said means for temporarily storing said coded data comprises paired sets of storage and print buffer circuitry each respectively storing two characters whereby the coded data representative of said two stored characters is successively gated from said storage buffer to said print buffer and to said means for printing by said means for determining said number of characters printed.

16. A printing system as in claim 9 wherein said control means further includes means responsive to said primary and secondary pulses from each of said master and slave controllers for determining the end of said selected multiple line message format and wherein said master and slave controllers are each responsive to an associated one of said end of message signals for terminating the generation of said primary and secondary pulses.

17. A method for printing variable alpha/numeric data in registered and aligned relationship with fixed data printed by a master plate cylinder on a moving web at press speeds, comprising the steps of:

providing coded data representative of the variable data in a selected multiple line message format and providing command signals;

generating character timing signals in response to said command signals representing the sequential position of said alpha/numeric data in said multiple line message format;

generating a top of form pulse for each revolution of said master cylinder prior to the mechanical top of form of said master cylinder;

generating first pulses having a pulse rate dependent on the speed of the web;

correcting said top of form pulse in accordance with said first pulses;

automatically adjusting said character timing signals to account for different web speeds and variable form depth data in accordance with said corrected top of form pulse; and

printing said variable data in response to said character timing signals by projecting independently controlled ink droplet streams onto said moving web.

18. A method as in claim 17 further including the step of establishing a number of different master cylinder form depths and said step of automatically adjusting the character timing signals includes correcting the top of form pulse in accordance with a desired one of said form depths.

19. A method as in claim 17 further comprising the step of generating a plurality of primary pulse trains, each train having a pulse rate determined at least partially by the speed of the moving web and a plurality of secondary pulse trains, each train spaced between a respective different one of said primary pulse trains, said primary pulse trains each denoting successive alpha/numeric characters and said secondary pulse trains each controlling a respective ink droplet stream.