US3765328A

US3765328A - Inker cam drive system

Info

Publication number: US3765328A
Application number: US00281103A
Authority: US
Inventors: E Treff; J Crum
Original assignee: Harris Intertype Corp
Current assignee: Harris Graphics Corp
Priority date: 1972-08-16
Filing date: 1972-08-16
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16
Also published as: CA1006048A; JPS4957906A; FR2196251A1; DE2341510A1; FR2196251B1; GB1427834A

Abstract

A printing press having one or more printing units has a separate motor for driving each inker cam mechanism. Each inker cam mechanism tracks the speed and phase of a selected gear driven by the main drive shaft of the press, with zero long-term position error. The speed ratio between each inker and the main drive shaft is individually controllable and the phase position of each inker with respect to the main drive shaft gear being tracked is also individually controllable. A primary tracking signal is derived from a tachometer on the main drive shaft of the press, and angular position errors are corrected by a feedback circuit. Error signals are generated by counting the pulses of an oscillator which occur between the time that the main drive gear reaches a predetermined angular position and the time that an inker cam mechanism reaches a predetermined angular position. The frequency of the oscillator whose pulses are being counted is made proportional to the square of press speed in order to make the error signal a constant percentage of a primary tracking signal.

Description

United States Patent [191 Treff et a1.

INKER CAM DRIVE SYSTEM Inventors: Ernest H. Treff, Groton; James N.

Crum, Stonington, both of Conn.

[73] Assignee: Harris Intertype Corporation,

Cleveland, Ohio Filed: Aug. 16, 1972 App]. No.: 281,103

U.S. C1 101/349, l0l/D1G.6, l0l/D1G. l4

[51] Int. Cl 1341f 31/14 [58] Field of Search ..l01/349352, 357, 361, 363, 148, 206209 [56] References Cited UNITED STATES PATENTS 3,274,932 9/1966 Caza 101/357 3,412,677 11/1968 Kanton 101/349X 3 608,486 9/1971 McDonald 101/365 3,688,696 9/1972 Treff 101/350 Primary ExaminerJ. Reed Fisher Attorney-Charles H. Grace et a1.

[111 3,765,328 Oct. 116, 1973 [57] ABSTRACT A printing press having one or more printing units has a separate motor for driving each inker cam mechanism. Each inker cam mechanism tracks the speed and phase of a selected gear driven by the main drive shaft of the press, with zero long-term position error. The speed ratio between each inker and the main drive shaft is individually controllable and the phase position of each inker with respect to the main drive shaft gear being tracked is also individually controllable.

18 Claims, 6 Drawing Figures mnjmmnm 16 ms 3.765.328

SHCU 10F 2 f i I 7 FIG! V FlGZm,

H 1 E V2 1 H636 i H 1 WA 1 I 1 l F1650 1 1 5 Ma l l Flesd l l nnnnnnnnn 1 INKER CAM DRIVE SYSTEM BACKGROUND OF THE INVENTION Lithographic offset priming presses often have several printing units driven by a single main drive motor from a main drive shaft, each printing unit printing a different color. Each printing unit has an inker mecha nism whose function is to distribute ink on a plate cylinder whose surface bears the image to be printed. The inker mechanism typically utilizes an ink fountain roll, an ink ductor roll and vibrator rolls which move axially for distributing the ink. Some of these rolls and their associated mechanisms are actuated by cams which take power irregularly and cyclically from the inker mechanism s driving source. Because of the nonuniform nature of the power taken by various parts of the inker mechanisms a separate motor has been used to drive each inker mechanism so that torque variations of the inker mechanism will not be reflected into the main drive of the press where they could have an adverse effect on print quality. The motor which drives the inker cam mechanism of each printing unit must track the speed of the main drive of the press or a speed proportional to it for high quality color printing. It is desirable for an inker cam drive system to track the main drive with zero long-term error and with control lable phase angle to prevent any change in the phase of inker operation between printing units. These requirements have exceeded the capability of inker cam drive systems of the prior art, especially in multiple unit printing presses.

SUMMARY OF THE INVENTION derived from a press tachometer which measures the speed of the main drive apparatus. This signal is attenuated by a selectable amount to cause the inker to track the press at a selected speed ratio.

A second signal controlling the inker cam motor is a feedback signal whose sign and magnitude depend upon the relative angular position of the inker cam mechanism and a selected gear driven from the main drive shaft. The second signal prevents a small speed error from accumulating to a significant position error after a time.

The second control signal is obtained by comparing the times of occurrence of two pulses. One pulse comes from an inker cam pulse generator and the other pulse comes from a pulse generator on a gear driven by the main drive shaft which is being tracked. Each pulse generator produces a pulse once for each revolution of the mechanism upon which it is mounted. The pulse from the inker cam pulse generator starts a window time interval and the pulse from the press pulse generator stops the time interval, or vice versa depending on which occurs first in a measurement cycle. The window time interval, which represents a position error, is measured digitally by counting relatively high frequency pulses which occur during the time interval, the pulses being generated by a voltage-to-frequency converter. The number of pulses from the voltage-to-frequency converter which occur within the window interval is counted and converted to an error signal by a digitalto-analog converter. The sign of the error signal has one polarity of the pulses from the inker cam pulse generator occurs after the pulse from the press pulse generator, and has another polarity if these windowdefining pulses occur in the reverse order. The magnitude and polarity of the error signal control a correction signal which is the second of the three signals controlling the inker cam drive motor. The second error signal operates to reduce the error in angular position between the inker cam mechanism and a gear on the main drive which is being tracked. The voltage-tofrequency converter is arranged to have an output frequency proportional to the square of the main press speed. Thus, the number of pulses in the window interval depends upon the press speed so that the error signal which drive the DC motor is proportioned to the speed of the press.

A third controlling signal is a time integral of the second signal. The second signal is integrated and the result is utilized as a contributing feedback signal to reduce the long-term angular position error to a negligible amount. The integrated error signal permits the inker cam mechanism to operate in steady state with essentially zero phase offset; a phase offset could exist as a result of voltage offsets in the control system if the integrator signal were not provided.

The inker cam mechanisms for individual printing units can be individually controlled as to speed by selecting one of several gears driven by the main drive shaft as the gear which is to be tracked by each inker cam drive mechanism. The relative phase of each of the inker cam drive mechanisms can be individually adjusted by adjusting the phase of each inker cam pulse generator.

One object of the present invention is to provide a printing press whose printing unit or units have separate inker cam drive systems which are individually adjustable in speed and which track the main drive apparatus. 7

Another object is to provide a printing press whose inker cam mechanism track the main drive with essentially zero long-term error.

Still another object is to provide a printing press having individual phase adjustments for its inker cam mechanism.

Yet another object is to provide a printing press with a particular, partly digital, control concept for its individual inker cam drive system.

Other objects and features of the invention will become more apparent upon a consideration of the following description taken in conjunction with accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a printing press driven by a single motor and having three printing units each with an inker cam mechanism;

FIG. 2 is an electrical schematic block diagram of the inker cam drive system showing pulse generators for detecting angular positions of parts of the system, a control circuit for processing the signals, and one inker cam drive motor;

FIG. 3A is a time graph showing a pulse from a pulse generator indicating the position of a gear connected to the main drive shaft;

FIG. 3B is a time graph showing a pulse from a pulse generator mounted on an inker cam mechanism;

FIG. 3C is a time graph of an electrical window signal whose duration represents a discrepancy in position which is to be corrected; and,

FIG. 3D is a time graph ofa group of pulses which are encompassed in the window of FIG. 3C and which appears at a terminal in the control circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT In a preferred embodiment of the invention, a printing press has several printing units 10, 12, 14, all of which are driven by a single electric motor 16, as shown in FIG. 1. A main drive shaft 18 extends from the motor 16 to all three printing units 10, 12, 14, each of which receives power from the drive shaft 18 through gearing 20, 22, 24, respectively. Each printing unit 10, 12, 14 has an inker comprising inker cam equipment 26, 28, 30 which typically includes ratchetactuated fountain rolls, ink ductor rolls, and ink distribution vibrator rolls having oscillatory motion, some or all of which are operated by cams. The inker equipment for each printing unit 10, 12, 14 is driven by an additional inker

cam drive motor

32, 34, 36 respectively. Torque loads imposed upon the

motors

32, 34, 36 by the inker cam equipment are time varying, changing in cyclically repeating patterns.

The time at which each inker cam mechanism 26, 28, 30 arrives at a particular angular position in its operating cycle is indicated electrically by an ink

cam pulse generator

38, 40, 42, which is connected to the inker mechanisms 26, 28, 30, respectively, and which will be described in more detail below. Three

more pulse generators

44, 46, 48 are connected to the main drive shaft 18 through sets of gears, each of which has a different gear ratio, so that the

press pulse generators

44, 46, 48 all track the main drive shaft 18 but with different speeds of rotation. Each press pulse generator produces an electrical pulse when it passes through a particular predetermined position in the course of its rotation. It will be shown below that each inker can selectively track any of the press pulse generators.

A DC tachometer 50 is mounted on the main drive shaft 18 to produce a DC voltage proportional to the speed of the shaft 18 for control purposes.

The inker

cam drive motors

32, 34, 36 are controlled by an electronic control unit 52 mounted on the press and having some manual controls 54 for use by an operator. The control equipment 52 utilizes signals from tachometer 50 and from the inker

cam pulse generators

38, 40, 42 and from the

press pulse generators

44, 46, 48 to control and regulate the inker

cam drive motors

32, 34, 36 in accordance with instructions entered at manual controls 54 by the operator. Also, the operator can enter inker phase settings at each inker

cam pulse generator

38, 40, 42 by mechanically adjusting those pulse generators. The operator therefore can predetermine the speed and the absolute phase angle of each inker cam equipment 26, 28, 30 relative to the main drive of the press.

A portion of control equipment 52 utilized for controlling the inker cam equipment 26 on one printing unit is shown in the block diagram FIG. 2. The control scheme involves a primary tracking signal and feedback signals.

For producing the primary tracking signal, press tachometer 50 generates a DC voltage which is proportional to the speed of main drive shaft 18. The DC voltage is connected through a conductor 56 to one pole 58 of a manual two-pole selector switch 54a. The position of selector switch 54a determines which of three

resistive attenuators

60a, 60b, 600 is selected by switch pole 58 for use in the circuit. Switch 54a selects the speed ratio between the press main drive shaft 18 and the inker cam mechanism 26. Each

attenuator

60a, 60b, 600 is preadjusted to attenuate the signal from tachometer 50 by a different amount. The attenuated signal at a junction 62 of the selectable attenuators 60a, 60b, 60c determines the nominal speed ratio between inker cam mechanism 26 and main drive shaft 18 of the press.

The signal at junction 62 is a primary tracking signal which provides more than 95 percent of the control signal required for operating inker cam drive motor 32.

The signal at terminal 62 is connected to a summing amplifier 64 whose output is connected to drive a conventional motor controller, such as SCR controller 66. SCR controller 66 serves as a power amplifier for providing DC control power to motor 32 which drives the inker cam mechanism 26.

The primary tracking signal at junction 62 acting alone would not provide sufficiently precise control of the inker cam mechanism 26. A feedback circuit is provided to control the system more precisely. The feedback circuit produces a correction signal on a circuit 68 and the time integral of the correction signal on another circuit 70, both of which add to the primary tracking signal at the input of summing amplifier 64. The correction signal and its integral signal are produced by feedback components including the ink cam pulse generator 38, one of the

press pulse generators

44, 46, 48 and other subcircuits to be described. The feedback circuit compares the time of occurrence of a pulse received from the ink cam pulse generator, with the time of occurrence of a pulse generated by a se' lected one of the press pulse generators, and produces signals which operate to control the inker cam mechanism 26 so that the pulses occur at the same time. Inker cam pulse generator 38 consists of a rotating gear or disc 71 having a ferrous discontinuity such as a magnetic stud 72 which passes a magnetic pickup coil 74 once per revolution of the disc 71. Upon each revolution an electrical pulse is induced in the magnetic pickup coil 74. Other types of pulse generators, for example photoelectric encoders, brush-type encoders, or cam actuated switches could be used to perform the same function. The magnetic pickup coil 74 is mounted so that its location is angularly adjustable to any. position around the disc 71. Its angular setting serves an absolute phase adjustment on the inker cam drive system 26.

Each of the

press pulse generators

44, 46, 48 has a disc 73, 75, 77, all of which are driven at different speeds from the main drive shaft 18. Each press pulse generator has a magnetic pickup coil 76, 78, for producing a pulse when a magnetic discontinuity on the associated disc passes the pickup coil. Each of the discs 73, 75, 77 represents a different possible reference whose speed the inker cam drive can be selected to track. Switch 54a has a transfer arm 82 which selects the electric ouput of one of the magnetic pickup coils 76, 78, 80 to select a speed at which the inker is to operate.

Pulses from coil 74 and from a selectedpress coil are connected to a gate circuit 84. Assuming that press coil 76 has been selected by switch 540, the pulse from coil 76 will be compared with the pulse from coil 74 as to time of occurrence. The first-occurring pulse starts a voltage signal herein called a window signal at output terminal 86 of the gate circuit 84; the second-occurring of the two coil pulses terminates the window signal at terminal 86. The duration of the voltage signal at terminal'86 is the time between occurrence of pulses from coils 74 and 76, irrespective of which pulse occurred first. FIGS. 3a, 3b, 30 show, respectively, the pulse signal from coil 76, the pulse signal from coil 74, and the window signal at terminal 86,-for a situation in which the inker cam mechanism lags the disc 73 which it is tracking.

A second output terminal 88 of the gate circuit 84 has a logic 1 signal if the pulse from coil 74 lags the pulse from coil 76 and has a logic zero signal if the pulse from coil 74 leads the pulse from coil 76. Thus, the signals at terminals 86 and 88 taken together are representative of the duration and sign of any discrepancy in timing between the inker 26 and the press pulse generator 44 which it is tracking. This information is subsequently converted to error signals for correcting the discrepancy.

The gate circuit 84 is arranged in the following way for producing its output signals. A'pulse from press coil 76 can set a flip-flop 90; a pulse from inker coil 74 can set a different flip-flop 92. The flip-flops shown are actuated by logic 0 signals. The gate circuit 84 is entirely symmetrical with respect to its'two coil inputs. A set condition in flip-flop 92 together with a reset condition in flip-flop 90' causes a zero logic signal from a'NAND gate 94. Similarly, simultaneous existence of a set condition of flip-flop 90 and a reset status of flip-flop 92 creates a zero output signal from a NAND gate 96. The outputs of NAND gates 94 and 96 are both connected to a NAND gate 98which, as used here, performs an OR function. The output ofNANDgate 98, which is at terminal 86, is a logic 1 whenever either one but not both of the flip-

flops

90, 92 is in a set condition. NAND gates 94, 96 and 98 function as an exclusive OR logic circuit with respect to the status of flip-

flops

90, and 92, and generate a window output signal at terminal 86. At the end of the window signal at terminal 86 flip-

flops

90 and 92 are both reset by a zero pulse froma oneshot multivibrator 102.

Another flip-flop 100 has its set and reset input terminals connected to outputs of NAND gates 96, 94, respectively. If the pulse from coil 76 occurs before the pulse from coil 74 NAND gate 96 sets flip-flop 100 and a logic 1 appears at the lag output terminal 88. If instead pulse 74 occurs first, NAND gate 94puts flip-flop 100 in a reset condition and the asserted output terminal 88 has a logic 0 signal. Flip-flop 100 is controlled only by the first-occurring pulse of the two pulses of each cycle because the second pulse is prevented from affecting flip-flop 100 by NAND gate 94'or NAND gate 96, depending upon whether the pulse from coil 76 or coil 74, respectively, occurred first.

A time sequence of operation of the gate circuit 84 is as follows. Flip-

flops

90 and 92 are both initially in a reset condition. Letting the pulse from coil 76 occur before the pulse from coil 74, the positive pulse from coil 76 is inverted in inverter 104, and flip-flop is set. Flip-flop 90 applies a logic 1 signal to one input of NAND gate 96 whose other input has a logic 1 from the negated output of flip-flop 92. NAND gate 96 has a zero output signal which sets flip-flop and produces a logic 1 signal at its asserted output terminal 88. The logic 0 signal from the output of NAND gate 96 causes NAND gate 98 to produce a logic 1 at its output terminal 86. This is the beginning of a window signal.

Coil 74 then produces a positive pulse which is in- 1 verted in inverter 106 causing flip-flop 92 to be set. The negated output terminal 108 of flip-flop 92 assumes a logic 0 signal which disables NAND gate 96 and causes NAND gate 96 to produce a logic 1 output. This causes NAND gate 98 to terminate the positive window signal at its terminal 86.

The window signal cannot be maintained by action of NAND gate 94 at this time because an input to NAND gate 94 from the negated output of flip-flop 90 causes NAND gate 94 to have a logic 1 signal. When the window signal at terminal 86 drops from a logic 1 to a logic 0, the one-shot multivibrator 102, which is responsive to down-going changes in its input signal, produces a short output pulse on a reset conductor 110 which resets flip-

fiops

90 and 92, thereby initializing the gate circuit 84 for the next cycle.

Gate circuit 84 includes also a NAND gate 112, one of whose inputs is enabled with a logic 1 signal only during thewindow signal interval at terminal 86. The other input of NAND gate 112 is energized by a relatively high frequency oscillating logic signal obtained from a voltage-to-frequency converter 114. The output of NAND gate 1 12 is inverted by an inverter 116 whose output terminal 124 has a burst of positive-going pulses, as in FIG. 3d. The duration T of the burst equals the duration of the window signal at terminal 86. The frequency of the pulses within the window is determined by the voltage-to-frequency converter 114. The number of pulses in a burst is therefore dependent upon both the time lag between the pulses from coils 76 and 74, and the frequency of pulses generated by voltage-to-frequency converter 114. The number of pulses in a burst is converted into an error signal by circuits to be described hereinbelow.

The voltage-to-frequency converter 1.14 operates continuously to produce at its output terminal 118 an oscillating logic signal whose frequency is proportional to an'analog voltage at its input terminal 120. The voltage at terminal l20 is proportional to the square of the voltage from press tachometer 50; a resistor and diode squaring circuit 122 operates as a nonlinear attenuator upon the signal from press tachometer 50 to produce the voltage proportional to the square of press speed. Circuit 122 has series-connected resistorsvin parallel individually with Zener diodes which are selected to conduct at progressively increasing levels of current flow through the series resistors. The frequency of pulses within the burst of pulses appearing at terminal 124 is in this way made proportional to the square of the speed of the printing press. The square function is employed so that for a given discrepancy in angular position of the inker mechanism 26, the error signals produced by the feedback circuit will be a fixed percentage of the primary tracking signal irrespective of press speed.

The burst of pulses at terminal 124 of gate circuit 84 is converted to error signals by first passing the pulses through a NAND gate 126 to the pulse input of a counter 128. The counter 128 is reset at the leading edge of the window signal by a pulse from a one-shot multivibrator 130. Multivibrator 130 is triggered by a signal output from an inverter 132 which inverts the window signal experienced at terminal 86. Upon each cycle of the ink cam pulse generator 38 the counter 128 counts the pulses in a burst of pulses, starting from the reset condition.

An asserted output of each stage of binary counter 128 is connected to one of a group of binary-weighted resistors 134 whose outputs are all combined into the input of an amplifier 136. Counter 128, resistors 134 and amplifier 136 collectively serve as a digital-toanalog converter to produce an analog voltage signal at the output of amplifier 136 which is proportional to the count in counter 128 and therefore proportional at the end of the window signal, to the number of pulses occurring in the window interval. On cycles in which the counter reaches its maximum counting capacity, a zero logic signal is produced at the output of a decoder 138 to disable NAND gate 126 and prevent any further pulses from entering counter 128.

The analog voltage output of amplifier 136 is applied to a conventional sample-and-hold circuit 140 and is accepted into that circuit upon occurrence of a latch pulse at a latch terminal 141. A latch pulse is produced at terminal 141 upon the trailing edge of the window signal at terminal 86 because of the operation ofa oneshot multivibrator 142. The trailing edge of the window signal at terminal 86 is a down-going voltage. It is transmitted through a NAND gate 144 and an inverter 145, and triggers the one-shot multivibrator 142 to produce the latch pulse. Thus, when the counter 128 has finished counting, the sample-and-hold circuit 140 accepts an analog representation of the final count and holds that value for an entire cycle. The latch pulse at terminal 141 of sample-and-hold circuit 140 can be produced also by the counts reaching the maximum counting capacity of counter 128, if that should occur before the end of the window signal at terminal 86. In that event, decoder 138 places a down-going logic signal on the input of NAND gate 144 which causes oneshot multivibrator 142 to produce a latch pulse.

The voltage sampled and held by circuit 140 is proportional only to the magnitude and not the sign of the desired correction signal. The sign of the correction signal is controlled by a realy 146 whose coil is driven by a transistor 148 under control of the signal at terminal 88 of gate circuit 84. If the pulse from inker coil 74 lags the pulse from the press coil 76, transistor 148 receies a positive base voltage and its collector circuit conducts current through the coil of relay 146, energizing the relay. Contacts 146a of the relay then open and contacts 146b close. In an energized condition of relay 146 an output signal from sample and hold circuit 140 is inverted by an inverting amplifier 150 and connected through contacts l46b to a terminal 152. If instead the pulse from coil 74 leads the pulse from coil 76, transistor 148 de-energizes relay 146 causing the output of sample-and-hold circuit 140 to be connected to terminal 152 through contacts 146a without a reversal of its sign.

The correction signal at terminal 152 passes through a resistive circuit 68 to the input of summing amplifier 64 where it combines with the primary tracking signal.

The signal at terminal 152 is connected also to the input of an integrator 154 of conventinal design. Integrator 154 integrates its input signal 152 with respect to time and applies the integrated result to a circuit through which it too is combined with the primary tracking signal at the input of summing amplifier 64. The integrator permits the inker to operate with essentially zero steady state phase error. If the integrator were omitted the unintegrated correction signal circuit 68 would have to supply sufficient signal to compensate the steady state deficiencies of the primary tracking signal circuit 62. Integrator 154 integrates the phase error signals of terminal 152 to that, after a short time, the integrator compensates for the steady state deficiencies of the primary tracking signal and the inker can operate with substantially zero phase error. Integrator 154 is reset to zero upon any cycle in which the counter 128 reaches its maximum count because decoder 138 thereupon supplies a logic 0 signal to a reset terminal of integrator 154.

In a typical steady state situation in which the inker 26 is being controlled by controller 52 the primary tracking signal at circuit 62 may provide 101 percent of the net signal present at the input to summing amplifier 64, and the integrator 154 may provide negative 1 percent of the net signal. The correction signal on circuit 68 may provide none of the steady state correction signal, but be standing ready to respond rapidly to correct transient distrubances in the relative phase of inker 26 with respect to the press drive. In a preferred form of the circuit of FIG. 2 the correction signal at terminal 152 never exceeds 5 percent of the primary tracking signal at conductor 56. The correction signal has been made proportional to the primary tracking signal at conductor 56 by making the frequency of pulses within the window proportional to the square of the press speed. The time duration T of the positive window signal at terminal 86 of gate circuit 84 is directly proportional to the phase error P existing between the inker cam pulse generator 38 and the selected press pulse generator, and is inversely proportional to press speed S. In equation form, T=bP/S, where b is a constant of proportionality. The number N of pulses in a pulse burst at terminal 124 is equal to the time duration T of the window signal multiplied by the frequencyfof the pulses contained within it; N=Tf. The frequency f of pulses produced by the voltage-to-frequency converter 114 is proportional to the square of press speed, that is, f=kS where k is a constant. Consequently, the number N of pulses in a pulse burst equals (bP/S) (kS or N=bkPS. The number of pulses contained in a pulse burst, which determines the magnitude of the error signal, is therefore proportional to the phase error P and to the press speed S, and consequently is porportional to the prmay tracking signal on conductor 56, a desirable feature. If it is desired instead to make the error signal proportional to the post-attenuation primary tracking sinal at t erminal 62 the circuit can easily be rearranged by those ordinary skill in the art to do so.

Other forms of the preferred embodiment can be made in which the frequency entering gate 112 is not proportional to the square of the press speed. One such form has the frequency proportional to the first power of the press speed instead of to the square; this is accomplished by omitting the squaring circuit 122 and connecting the press tachometer 50 directly to the 9. voltage-to-frequency converter114. Another form has the frequency independent of press speed; a constantfrequency oscillator instead of a voltage-to-frequency converter is employed.

The speed change gearing 73, 75, 77 could act upon the ink cam pulse generator instead of upon the press pulse generator to produce relative speeddifferences.

Control circuits for other printing units 12 and 14 of the printing press are also included in controller 52 and are identical to certain portions of the circuits shown in F IG. 2. Connections to circuits for these other printing units are shown at

terminals

156, 158, 160 and 162 of FIG. 2. Each printing unit l0, 12, 14 has its own ratio selector switch, such as switch 54a. Consequently, the inkers of the various printing units can be operated not only at equal speeds, but at different speeds if desired, and still be phase-synchronized among themselves to the extent that their ratio of frequencies permits phase coherence.

What is claimed is:

1. A printing press having a main drive apparatus for rotationally driving a plurality of printing units each of which includes an inker cam mechanism for cyclically inking the corresponding printing unit, comprising an individual motive source connected to each inker cam mechanism for rotationally powering the mechanism, means for providing a first control signal in dependence upon the speed of the main drive apparatus, means communicating with the main drive apparatus and with each inker cam mechanism for sensing relative travel of the main drive apparatus and each inker cam mecha? nism and producing error signals accordingly, and a control circuit receiving said first control signal and said error signals and having outputs connected to said individual motive sources for controlling each of said inker cam mechanisms to track the main drive apparatus in dependence upon the control sinal and upon the error signal that corresponds respectively to each inker cam mechanism.

2. A printing press as defined in claim 1, wherein said means for sensing comprises adjustment meas for individually affecting the error signals corresponding to the inker cam mechanism to individually adjust the relative travel and therefore the angular tracking positions of the inker cam mechanisms.

3. A printing press as defined in claim 1 wherein said means for sensing relative travel comprises means for providing at least one cyclically repetitive signal of a frequency proportional by a proportionality ratio to main drive apparatus speed, and means for producing cyclically repetitive signals each of a frequency proportional by a proportionality ratio to an inker cam mechanism speed, and means for altering at least one of said proportionality ratios of said main drive apparatus speed and said inker cam mechanism speed, whereby at least one inker cam mechanism speed'is altered relative to said main drive apparatus speed.

4. A printing press as defined in claim 1 wherein said means for sensing relative travel comprises at least one press position indicator pulse generator for generating a position signal upon each completion of a predetermined amount of travel of said main drive apparatus, at least one inker cam position indicator for generating a position signal upon each completion of another predetermined amount of travel of a corresponding inker cam mechanism, and error measurement means receiving the position signals from said press position indicator and from said inker cam position indicator for producing said error signals in dependence upon the relative times of occurrence of the position signal from the press position indicator and the position signal from the inker cam position indicator.

5. A printing press as defined in claim 4 wherein said error measurement means comprises a gate circuit connected to be enabled by position signals from one of said press position indicator and said inker cam position indicator, and to be disabled by the other of said press position indicator and said inker cam position indicator, oscillator means connected to said gate circuit for producing cyclic signals, said cyclic signals being transmitted and blocked by said gate circuit according to whether said gate circuit is currently enabled or disabled, and signal accumulation means connected to receive and accumulate a number of signals in a transmitted group of signals from said gate circuit when said gate circuit is enabled for determining the magnitude of said error signal in dependence upon the number of signals in the transmitted group.

6. A printing press as defined in claim 5 wherein said oscillator meanscomprises a device for measuring the speed of the main drive apparatus and means for controlling the frequency of the cyclic output signals in dependence upon the speed of the main drive apparatus.

7. Aprinting press as defined in claim 5 wherein said signal accumulation means comprises a digital counter and a digital-to-analog converter.

8. A printing press as defined in claim 4 wherein said error measurement means comprises a logic circuit for producing an error sign signal, said error sign signal indicating a first polarity of error when said position signal from said press position indicator precedes said position signal from said inker cam position signal in an error measurement, and indicating a second polarity of error when said position signal from said inker cam poistion indicator precedes said position signal from said press position indicator.

9. A printing press as defined in claim 1 wherein said control circuit comprises an integrator for integrating each of said error signals and a circuit responsive to a plurality of input signals including a signal proportioned to said first control signal, including a second signal proportioned to said relative travel, and including a third signal proportioned to a time integral of said relative travel.

10. A printing press having a main drive apparatus for rotationally driving a plurality of printing units each of which includes an individual inker cam mechanism for cyclically inking the corresponding printing unit, comprising an individual drive source connected to each inker cam mechanism for powering it, press phase means communicating with said main power apparatus for sensingrotational phases related to said main drive apparatus and producing at least one periodic signal in dependence upon said phases, inker phase means communicating with each of said inker cam mechanisms for sensing a phase related to each inker cam mechanism and producing a periodic signal in dependence thereon corresponding to each mechanism, comparator means for comparing at least one of said signal from said press phase means and said signal from each of said inker phase means and producing an error signal corresponding to a position error of each inker cam mechanism, and a control circuit for controlling each of said individual drive sources in response to the corresponding error signal of each inker cam mechanism to reduce each of said error signals, whereby the inker cam mechanism track the main drive apparatus phase coherently.

11. A printing press as defined in claim and further comprising phase adjustment means connected to at least one of said press phase means and said inker phase means for altering by a predetermined amount the phase of at least one of said signals produced by said press phase means and by said inker phase means.

12. A printing press as defined in claim 10 wherein at least one of said press phase means and said inker phase means comprises speed selection means for predetermining a ratio of frequency of at least one of the periodic signals which they respectively produce to the speed of said main drive apparatus said inker cam mechanism respectively.

13. A printing press as defined in claim 10 wherein said press phase comprises compriss signal production means for producing at least one signal, and wherein said speed selection means comprises gear selection means having a plurality of selectable gear ratios for connecting said main drive apparatus to said signal production means with different speed ratios between said main drive apparatus and said signal production means.

14. A printing press having a main drive apparatus for rotationally driving a printing unit which includes an inker cam mechanism for cyclically inking the printing unit, comprising an individual motive source connected to the inker cam mechanism for rotationally powering the mechanism, means for providing a first control signal in dependence upon the speed of the main drive apparatus, means communicating with the main drive apparatus and wth the inker cam mechanism for sensing relative travel of the main drive apparatus and the inker cam mechanism and producing error signals accordingly, and a control circuit receiving said first control signal and said error signals and having an output connected to said motive source for controlling said inker cam mechanism to track the main drive apparatus in dependence upon the control signal and upon the error signals, said means for sensing comprising adjustment means for affecting the error signals to adjust the relative travel and therefore the angular tracking position of the inker cam mechanism.

15. A printing press as defined in claim 14 wherein said means for sensing relative travel comprises at least one press position indicator pulse generator for generating a position signal upon each completion of a predetermined amount of travel of said main drive apparatus, at least one inker cam position for generating a position signal upon each completion of another predetermined amount of travel of the inker cam mechanism, and error measurement means receiving the position signals from said press position indicator and from said inker cam position indicator for producing said error signals in dependence upon the relative times of occurrence of the position signal from the press position indicator and the position signal from the inker cam position indicator.

16. A printing press as defined in claim 15 wherein said error measurement means comprises a gate circuit connected to be enabled by position signals from one of said press position indicator and said inker cam position indicator, and to be disabled by the other of said press position indicator and said inker cam position indicator, oscillator means connected to said gate circuit for producing cyclic signals, aid cyclic signals being transmitted and blocked by said gate circuit according to whether said gate circuit is currently enabled or disabled, and signal accumulation means connected to receive and accumulate a number of signals in a transmitted group of signals from said gate circuit when said gate circuit is enabled for determining the magnitude of said error signal in dependence upon the number of signals in the transmitted group.

17. A printing press as defined in claim 16 wherein said oscillator means comprises a device for measuring the speed of the main drive apparatus and means for controlling the frequency of the cyclic output signals in dependence upon the speed of the main drive apparatus.

18. A printing press as defined in claim 14 wherein said control circuit comprises an integrator for integrating each of said error signals and a circuit responsive to a plurality of input signals including a signal proportioned to said first control signal, including a second signal proportioned to said relative signal, and including a third signal proportioned to a time integral of said relative travel.

UNITED STATES PATENT oFMcE CERTIFICATE OF CGRRQHN Patent No. 3,7 5,3 Dated October 16, 1973 Inventor(S)EIneS'b H. Treff et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 12, line 5, after "position" insert --indicat or Column line change gnal" second occurrence w m travel Signed and sealed this 26th day of March 19711..

(SEAL) Attest:

EDWARD MJLETCHER, J'R C MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-10SO (10-69) USCOMM-DC 6O376-P69 A U.S. GOVERNMENT PRINTING OFFICE: I969 O-366-334, a

Claims

1. A printing press having a main drive apparatus for rotationally driving a plurality of printing units each of which includes an inker cam mechanism for cyclically inking the corresponding printing unit, comprising an individual motive source connected to each inker cam mechanism for rotationally powering the mechanism, means for providing a first control signal in dependence upon the speed of the main drive apparatus, means communicating with the main drive apparatus and with each inker cam mechanism for sensing relative travel of the main drive apparatus and each inker cam mechanism and producing error signals accordingly, and a control circuit receiving said first control signal and said error signals and having outputs connected to said individual motive sources for controlling each of said inker cam mechanisms to track the main drive apparatus in dependence upon the control signal and upon the error signal that corresponds respectively to each inker cam mechanism.

2. A printing press as defined in claim 1, wherein said means for sensing comprises adjustment means for individually affecting the error signals corresponding to the inker cam mechanism to individually adjust the relative travel and therefore the angular tracking positions of the inker cam mechanisms.

3. A printing press as defined in claim 1 wherein said means for sensing relative travel comprises means for providing at least one cyclically repetitive signal of a frequency proportional by a proPortionality ratio to main drive apparatus speed, and means for producing cyclically repetitive signals each of a frequency proportional by a proportionality ratio to an inker cam mechanism speed, and means for altering at least one of said proportionality ratios of said main drive apparatus speed and said inker cam mechanism speed, whereby at least one inker cam mechanism speed is altered relative to said main drive apparatus speed.

6. A printing press as defined in claim 5 wherein said oscillator means comprises a device for measuring the speed of the main drive apparatus and means for controlling the frequency of the cyclic output signals in dependence upon the speed of the main drive apparatus.

7. A printing press as defined in claim 5 wherein said signal accumulation means comprises a digital counter and a digital-to-analog converter.

10. A printing press having a main drive apparatus for rotationally driving a plurality of printing units each of which includes an individual inker cam mechanism for cyclically inking the corresponding printing unit, comprising an individual drive source connected to each inker cam mechanism for powering it, press phase means communicating with said main power apparatus for sensing rotational phases related to said main drive apparatus and producing at least one periodic signal in dependence upon said phases, inker phase means communicating with each of said inker cam mechanisms for sensing a phase related to each inker cam mechanism and producing a periodic signal in dependence thereon corresponding to each mechanism, comparator means for comparing at least one of said signal from said press phase means and said signal from each of said inker phase means and producing an error signal corresponding to a position error of each inker cam mechanism, and a control circuit for controlling each of said individual drive sources in response to the corresponding error signal of each inker cam mechanism to reduce each of said error signals, whereby the inker cam mechanism track the main drive apparatus phase coherently.

11. A printing press as defined in claim 10 and further comprising phase adjustment means connected to at least one of said press phase means and said inker phase means for altering by a predetermined amount the phase of at least one of said signals produced by said press phase means and by said inker phase means.

13. A printing press as defined in claim 10 wherein said press phase means comprises signal production means for producing at least one signal, and wherein said speed selection means comprises gear selection means having a plurality of selectable gear ratios for connecting said main drive apparatus to said signal production means with different speed ratios between said main drive apparatus and said signal production means.

16. A printing press as defined in claim 15 wherein said error measurement means comprises a gate circuit connected to be enabled by position signals from one of said press position indicator and said inker cam position indicator, and to be disabled by the other of said press position indicator and said inker cam position indicator, oscillator means connected to said gate circuit for producing cyclic signals, said cyclic signals being transmitted and blocked by said gate circuit According to whether said gate circuit is currently enabled or disabled, and signal accumulation means connected to receive and accumulate a number of signals in a transmitted group of signals from said gate circuit when said gate circuit is enabled for determining the magnitude of said error signal in dependence upon the number of signals in the transmitted group.

18. A printing press as defined in claim 14 wherein said control circuit comprises an integrator for integrating each of said error signals and a circuit responsive to a plurality of input signals including a signal proportioned to said first control signal, including a second signal proportioned to said relative travel, and including a third signal proportioned to a time integral of said relative travel.