US3152542A

US3152542A - Devices for automatically preadjusting the different elements of a printing machine

Info

Publication number: US3152542A
Application number: US194782A
Authority: US
Inventors: Chambon Louis Jean
Original assignee: Machines Speciales Sa Soc Et
Current assignee: Societe dEtudes de Machines Speciales SA
Priority date: 1961-05-19
Filing date: 1962-05-15
Publication date: 1964-10-13
Anticipated expiration: 1981-10-13
Also published as: FR1297289A

Description

Oct. 13, 1964 L. J. CHAMBON 3,152,542

DEVICES FOR AUTOMATICALLY PREADJUSTI-NG was DIFFERENT ELEMENTS OF A PRINTING MACHINE Filed Ilay 15. 1962 3 Sheets-Sheet 1 C an m A 09 G O A '1 i OD H E 00 Oct. 13, 1964 J. CHAMBON 3,152,542

, DEVICES FOR AUTOMATICALLY PREADJUSTING THE DIFFERENT ELEMENTS OF A PRINTING MACHINE 5 Sheets-Sheet 2 Filed May 15, 1962 D on N. fimw an. 0 E mm mm mm flmn w? W S 1 KS 8 u n T l a 17 & h ml u & Y h P i .r .i U m 1 1964 L. J. CHAMBON 3,152,542

DEVICES FOR AUTOMATICALLY PREADJUSTING THE; DIFFERENT ELEMENTS OF A PRINTING MACHINE Filed May 15, 1962 5 Sheets-Sheet 3 United States Patent 3,152,542 DEVICES FOR AUTOMATICALLY PREADJUSTING THE DIFFERENT ELEMENTS OF A PRINTING MACHlNE Louis Jean Chambon, Paris, France, assignor to Socicte dEtudes de Machines Speciales, Socit Anonyme, Paris, France Filed May 15, 1962, Ser. No. 194,782 Claims priority, application France, May 19, 1961, 862,281, Patent 1,297,289; Apr. 6, 1962, 893,585, Patent 1,297,289

6 Claims. (Cl. 101-181) The present invention relates to a device for automatically preadjusting the different elements of a printing machine, notably multi-color printing machines.

Various devices have already been proposed up to now for adjusting the printing cylinders of a machine of this character. These devices are based on feelers or detectors responsive on the one hand to the passage of a reference mark carried by the web of paper or similar material on which the printing is to be effected and, on the other hand, to the passage of a reference mark carried by the printing cylinder of another member driven in synchronism therewith. In all known devices of this character the reference mark carried by the paper web or the like is applied thereto by the printing cylinder proper. The signals deriving from the reading of the reference mark carried by the paper web and of the reference mark carried by the printing cylinder are transmitted to a comparator device of which the output signal is adapted, through a servomotor and a differential, to accelerate or retard the printing cylinder according to the plus or minus sign characterizing the difference between the two signals resulting from this detection.

The present invention aims at improving this adjusting device whereby the preadjustment of the complete printing machine is rendered completely automatic, when the machine operation is started for a printing run, without requiring any manual intervention. To this end the automatic device for preadjusting different elements of a printing machine, wherein the paper web or like band travels through successive printing apparatus comprising, for each printing apparatus, a first detector disposed on the path of the Web and emitting a first signal when a reference mark carried by the web moves past said first detector, and a second detector emitting a second signal when a reference mark carried by the printing cylinder of the apparatus moves past said second detector, 21 com parator receiving said first and second signals at its input end and delivering at its output end a pulse of which the duration is a function of the phase shift, if any, existing between said first and second signals, the sign of said pulse depending on the order in which said first and second signals occur at the inlet end of said comparator, and a servomotor connected to the output end of said comparator and controlling the deceleration or acceleration of said printing cylinder, is characterized in that it comprises a pro-marking device adapted, before the passage of the paper or like web through the first printing apparatus, to apply on said web the mark disposed at regular intervals corresponding to the printed size, whereby the adjustment of each printing apparatus takes place automatically, when the paper web is inserted into the printing machine, by virtue only of the comparison of the successive reference marks carried by the paper web and by the printing cylinder.

The preadjustment device according to the invention is advantageous in that each printing apparatus is set automatically in relation to the mark carried by the paper web. Therefore, any preliminary adjustment of the printing apparatus with respect to one another and any adjustment of the printing in relation to the subsequent operations, if

i'icc any, such as cutting to size, cutting out, etc., can be dispensed with.

The preadjusting device according to this invention is also advantageous in that it is not necessary, when the printing size is modified, to change the position of the detector responsive to the passage of the reference marks carried by the paper web. On the other hand, in the known devices wherein the reference marks are applied to the paper web by the printing cylinders themselves, the detector reading these marks must necessarily be placed in the vicinity of these paper webs, at a distance relative to the printing cylinder which varies with the size.

The reference mark carried by the paper web may be applied thereto through any suitable means. This mark may be printed or formed by means of a magnetic ink permitting its detection through adequate apparatus when the paper web travels through the printing apparatus.

The printing cylinder reference marks of the different printing cylinders are applied simultaneously with the engraving of these cylinders, along the marginal portion thereof, whereby this mark is not printed on the paper web and is thus properly positioned in relation to the engraving of each cylinder.

A typical embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic illustration of the basic principles of the invention;

FIGURE 2 is another diagram illustrating the basic principles of the comparator means utilized in the inven- FIGURES 3A to 3C are diagrams showing the shape of the different signals occurring in the device of the invention; and

FIGURE 4 is a wiring diagram of the control means of the device.

In FIG. 1, the printing machine illustrated in diagrammatic form only comprises a plurality of printing apparatus, A, B through which a paper web or like band 1 is caused to travel. In the successive apparatus A, B this web receives printings of different colors. Reference -marks m are applied to the web at regular longitudinal intervals. These marks are applied to the paper web 1 by a preliminary marking device I, for example on the nonprinted face. The interval between two consecutive marks In corresponds to the pitch of the printing cylinders, that is, to the size length. These marks m may be either printed or applied by using magnetic ink, and they are adapted to be read as the paper web travels through the different printing apparatus, A, B

A

device comprising detectors

11, 13 and a comparator 14- is associated with each printing apparatus. The first detector 11-which may be of the photoelectric, electromagnetic or other type according to the nature of the reference mark mis disposed along the path of the paper web 1 and placed in each printing apparatus at the same distance from the line of contact between the printing cylinder 2 and its counterpart. This detector 11 is responsive to the passage of the marks in of the different sizes.

The other detector 13 is located in close proximity of the printing cylinder 2, at any point along its periphery. However, the position of detector 13 in relation to the periphery of the printing cylinder 2 is the same in all printing apparatus. The engraving on this cylinder 2 comprises a mark m the passage of which is detected during each revolution of the cylinder by the detector 13.

The printing cylinders 2 of the successive printing apparatus A, B are rotatably driven from a common driving shaft 3 through gears 4, S and a differential 6 the output shaft 7 of which drives the corresponding printing cylinder.

The

detectors

11 and 13 are connected to the

inputs

14a and 14b respectively of comparator 14, the output a of this comparator being connected in turn to a servomotor 8 controlling the differential 6.

Reference will now be made to FIG. 2 to describe a preferred embodiment of the comparator device 14 associated with each printing apparatus.

The detectors l2 and 13 are connected to the control inputs 21c and 226 respectively of

multivibrators

21 and 22. The first multivibrator 21 is of the monostable type in that it is reset automatically a certain time after its actuation. On the other hand, the other multivibrator 22 is of the bistable type. Besides, the functions of these multivibrators could be inverted, that is, multivibrator 21 could be a bistable multivibrator and multivibrator 22 a monostable one, without any inconvenience.

Multivibrators

21 and 22 may be constructed according to diagrams well known in the field and by using elements such as valves, tubes, transistors, cold cathode tubes, etc. In their inoperative condition, that is, when they are reset, these

multivibrators

21 and 22 deliver from their

output terminals

21a, 21b, and 22a, 22b, respectively, signals of the type illustrated in the diagrams of FIG. 3 wherein the time (abscissa) is plotted against the voltage (ordinates). In the inoperative condition the electronic elements (tubes, transistors, etc.) of the left-hand half of

inultivibrators

21 and 22 are assumed to be conducting whereas the elements in the right-hand half are nonconducting. This causes signals having low-voltage values to be produced at

terminals

21b and 22b. On the other hand the output 210 of the monostable multivibrator 211i is connected to the reset input 22r of the bistable multia vibrator 22.

The back output 21a and front output 221) of multivibrators 2i and 22 respectively are connected to the

inputs

23a and 23b respectively of an AND gate 23 delivering a signal from its output 23c only when higl1-voltage signals are applied concurrently to its

inputs

23a and 23b. Similarly, the front output 21b and back output 22a of

multivibrators

21 and 22 respectively are connected to the inputs 24a and 24b of another AND gate 24 respectively having its output 240 adapted to deliver a signal only when high-voltage signals are applied concurrently to its inputs 24a and 24b.

The outputs 23c and 240 of

AND gates

23 and 24 are connected to a device 29 illustrated in block form in the figure and controlling the energization, in one or the other direction, of a servomotor 8 for accelerating or decelerating the printing cylinder 2.

Now the operation of the comparator device of this invention will be described in a simplified manner with reference to the diagram of FIGS. 2 and 3. The

multivibrators

21 and 22 being in their inoperative condition, that is, when the elements disposed in the left-hand portion of these multivibrators are conducting, the signals present at the

output terminals

21a and 22a are at a low level, while the signals present (before the time t in FIG. 3A) at the output terminals 21b and 2217 are at a high level. As a result, none of the

AND gates

23 or 24 is conditioned completely and no signal appears at the

outputs

23c and 24c of these gates.

It will firstly be assumed that the reference mark m carried by the paper web 1 and the reference mark m carried by the printing cylinder 2 move simultaneously past their

corresponding detectors

12 and 13. Therefore, these detectors apply simultaneously (at the time t of FIG. 3A) release signals to terminals 2lle and 222 of

multivibrators

21 and 22. These multivibrators will then move to their operative or front position in which the voltage levels of the output signals are inverted. As a result, the input 23a of gate 23 receives a high-voltage signal and the other input 23b receives a low-voltage signal. The same applies to gate 24 receiving at its input 24a a low-voltage signal and a high-voltage signal at its input 24b. In this case too none of these gates is fully conditioned and therefore no signal is produced at the outputs 23c and 240.

After a time period T following its actuation, the monostable multivibrator 21 resumes automatically its inoperative position and the consequent voltage drop at the output terminal 21a is transmitted to the reset terminal 22r of bistable multivibrator 22 in order to restore the inoperative condition thereof.

Now it will be assumed that the printing cylinder 2 is leading in relation to the paper web 1, due to the fact that the passage of the reference mark m is detected first by the photoelectric cell or like detector 13. Thus, the latter emits alone at time t (FIG. 38) a release signal applied to the input 22e, thus causing the multivibrator 22 to become operative. Thus, this multivibrator produces a high-voltage signal at its output terminal 22a and a lowvoltage signal at its output terminal 22b. In FIG. 3B it will be seen that the high-voltage signals are produced simultaneously at the output terminals 22a and 2112, these signals being transmitted to the inputs of gate 24 which is fully conditioned. This gate will thus deliver an output signal at 240 which lasts until the multivibrator 21 becomes also operative, that is, at time 1 when the passage of reference mark in is detected by the photoelectric cell or like detector 12. Therefore, at the output of gate 24 there is obtained a signal of which the duration I 4 corresponds to the time period elapsing between the passages of marks in; and In past their corresponding detectors, that is, the de-synchronization difference to be compensated. This signal is applied to device 20 controlling the energization of servomotor 8 which will be described presently in detail with reference to FIG. 4.

The

multivibrators

21 and 22 are reset as before after a time period T following time t In case the paper web 1 were leading the printing cylinder 2, the photocell or like detector 12, at time i (FIG. 3C) will switch the monostable multivibrator 21 to its operative condition, the bistable multivibrator 22 being still inoperative. Under these conditions it will be seen that gate 23 is fully conditioned (FIG. 3C) since the input signals applied to its

terminals

23a and 23b are both of the high-voltage type. This gate 23 delivers a signal at its output 230 which lasts until the bistable multivibrator 22 is caused to assume its operative condition by the photocell or like detector 13 when the latter detects the passage of reference mark in (at time 12;). In this case too, the gate 23 delivers at its output end a signal of which the duration t -t equals the time period elapsing between the passages of marks in and m past their relevant detectors.

The multivibrator 21 is reset as in the preceding case after a time period T and after the latter has commenced at time i this resetting involving at the same time the resetting of the bistable multivibrator 22.

According to a modified embodiment of the invention both

multivibrators

21 and 22 could be of the bistable type and adapted to be reset at a predetermined point of the cycle by a reset pulse generator driven in synchronism with the printing cylinder 2.

On the other hand, the output signals from the

ET gates

23 and 24 may be used for controlling the pressure exerted by the counterpart 19 on the printing cylinder 2. To this end, the winding of an electromagnet 18 con trolling the holding of counterpart 19 away from the printing cylinder 2 may be connected to an amplifier 17 adapted to integrate the output signal from one or the

other gate

23 or 24. As long as the integrated current delivered by the amplifier 17 exceeds a predetermined threshold, that is, as long as either of the AND

gates

23 or 24 delivers an output signal of non-negligible duration, the electromagnet 18 remains energized and prevents the counterpart 19 from exerting a pressure on cylinder 2. When the output signal of the AND gates becomes negligible, the electromagnet 13 is de-energized and the counterpart 19 is applied automatically with pressure on the cylinder 2 when the proper synchronization is established between the paper web l and this cylinder 2.

Now reference will be made to FIG. 4 to describe a specific form of embodiment of the invention. The monostable multivibrator 21 comprises two triodes 25 and 26 and the bistable multivibrator 22 comprises two

triodes

27 and 28. The anodes of

triodes

25, 26, 27 and 28 are connected respectively to the

output terminals

21a, 21b, 22a and 22b of the two multivibrators. The anode of triode 25 is connected through a resistance 29 and a diode 30 in parallel and through a series-connected capacitor 31 to the grid of triode 26. This grid is connected on the other hand through a resistance 32 and a parallel-connected diode 33 to the junction point 34 between

resistances

35 and 36. These

resistances

35 and 36 are shunt-connected to the anode-cathode circuit of a triode 37 having its grid connected on the one hand to capacitor 38 and resistance 39 in parallel, and on the other hand through a resistance 41 to the anode of triode25.

On the other hand, the anode of triode 25, that is, the output terminal 21a is connected through a resistance 42 and through capacitors 43, 44 to the grid of triode 28 in the bistable multivibrator 22. The junction point between capacitors 43 and 44 is earthed through a diode 45.

The photocell 12 is connected through a capacitor 46 to the grid of a triode 47 having its anode connected through a capacitor 48 to the grid of triode 25 in the monostable multivibrator 21. Similarly, the photocell 13 is connected through a capacitor 49 to the grid of a triode 51 having its anode connected through a capacitor 52 to the grid of triode 27 in the bistable multivibrator 22 The different component elements of the comparison device are energized through a center-tap transformer 53, a pair of rectifiers 54 and a filter 55.

The AND

gates

23 and 24 comprise respectively triodes 56 and 57 having their cathodes connected to the output terminals 230 and 240. The grid of triode 56 is connected on the one hand through a resistor 58 to the output terminal 22b (i.e. the anode of triode 28) and, on the other hand, through a resistance 59, to the output terminal 21a (i.e. the anode of triode 25). Besides, the grid of triode 57 is connected on the one hand through a resistance 61 to the output terminal 21b (i.e. the anode of triode 26) and, on the other hand through a resistance 62 to the output terminal 22a (i.e. the anode of triode 27).

The output terminals 230 and 24c of AND

gates

23 and 24 are connected to the positive terminals of the biasing voltage sources 63 and 64 respectively, the negative terminals of these sources being connected to the grids of pairs of

thyratrons

65, 66 on the one hand, and 67, 68 on the other hand. The anodes of thyratrons 65 to 68 are connected to a feed transformer 69 having a grounded center tap. The cathodes of

thyratrons

65 and 66 are connected in common on the one hand to one terminal 8a of the armature of servomotor 8 and on the other hand to a parallel-resistance 71. Similarly, the cathodes of thyratrons 67 and 68 are connected in common on the one hand to the other terminal 8a of the servomotor armature and on the other hand to the parallel resistance 72.

The operation of the device illustrated in FIG. 4 is the same as that described hereabove in connection with FIG. 2 regarding the functions of

multivibrators

21 and 22 and

gates

23 and 24. Thus, when the photocell is energized, it transmits a positive release signal through capacitor 46 to the grid of triode 47 which becomes conducting. Therefore, the voltage drop occurring at the anode of triode 47 will block the triode 25, thus producing a high-voltage signal at the anode of this triode and therefore at the output terminal 21a. This positive signal is transmitted through capacitor 31 to the grid of triode 26 which becomes conducting. The time interval during which the monostable multivibrator 21 is operative is subordinate to the value of

elements

29, 31 and 32 and also to the biasing of the junction point 34. The triode 37 being rendered conducting by the integration of the signal appearing at the anode of triode 25, the biasing of junction pleting one cycle, that is, in fact the linear velocity of the paper web. The value of resistances 29 and 32 is so selected that the time-lag occurring before resetting is as close as possible to half a cycle.

From the wiring diagram of FIG. 4 it will be seen that when the multivibrator 21 is reset, that is, when the triode 26 is again non-conducting, the positive pulse appearing at the anode of this triode is fed to the grid of triode 25 in order to render the latter conducting. The negative pulse thus obtained at the anode of triode 25, that is, the output terminal 21a, is transmitted through resistance 42 and capacitors 43 and 44 to the grid of triode 28 in multivibrator ,22 in order to restore the latter to its inoperative condition. The diode 45 is provided in order to suppress the action of positive pulses.

The operation of AND

gates

23 and 24 is clearly apparent from the above description of the diagram; in fact, the voltage obtaining at

the'two input terminals

23a and 23b must be relatively high, i.e., the

triodes

25 and 28 must be blocked, to make the triode 56 conducting and to produce a high-voltage signal at the output terminal 230. The gate 57 operates in a similar manner except that it is only when the triodes 26 and 27 are blocked that triode 57 is conducting and a high-voltage signal appears at the output terminal 240.

When the printing cylinder is leading in relation to the paper web, the gate 24, as already explained, emits from its output terminal 24c a high-voltage signal the duration of which is proportional to the de-synchronization gap between the paper web and the printing cylinder. This positive signal is transmitted through the source 64 of biasing voltage to the grids of thyratrons 67 and 68 which are thus fired. A +1 current flows then through the armature of servomotor 8 and retards the motion of printing cylinder 2.

On the other hand, if the printing cylinder 2 is lagging in relation to the paper web 1 the gate 23 delivers from its output 23c a positive signal transmitted through the biasing voltage source 63 to the grids of

thyratrons

65 and 66 which are thus fired in turn. Then a -I current is allowed to pass therethrough to energize the armature of servomotor 8, thereby accelerating the printing cylinder 2.

The negative biasing of the grids of thyratrons 65 to 68, which is due to the voltage sources 63 and 64, should be sufiicient to counterbalance amply the negative biasing at terminals 8a and 8b of servomotor 8 when the current returns through the resistances 71 and 72. This occurs when the servomotor 8 operates as a generator after the energizing pulse has been suppressed.

What I claim is:

1. A device for automatically preadjusting different elements of a printing machine, wherein a web of paper or similar material travels through consecutive printing apparatus, which comprises a preliminary marking device for applying on said paper web, prior to its passage through the first printing apparatus, first reference marks disposed at regular intervals corresponding to the printed size, each printing apparatus comprising a first detector disposed in the path of said web and adapted to emit a first signal when said first detector reads the passage of a first reference mark carried by said web, and a second detector emitting another signal when said second detector reads the passage of a second reference mark carried by the printing cylinder of the apparatus, said second reference mark being formed in the marginal portion of said printing cylinder, simultaneously with the cylinder engraving, said first and second detectors being disposed at the same relative positions in the different successive printing apparatus, a comparator comprising a first multivibrator and a second multivibrator having each an input, a back output and a front output, said first and second signals emitted from said first and second detectors being respectively applied to the inputs of said first and second multivibrators, means for resetting both multivibrators during each cycle, a logical circuit connected to the outputs of said first and second multivibrators and delivering at its output a pulse the duration of which is a function of the possible phase shift existing between said first and second signals and the sign of which depends on the order in which said first and second signals occur at the input of said comparator, and a servomotor connected to the output of said comparator and adapted to control the deceleration or the acceleration of said printing cylinder, whereby the adjustment of each printing apparatus takes place automatically when a paper web is introduced into the printing machine due only to the comparison of the consecutive reference marks carried by the web and of the mark carried by the printing cylinder.

2. A device as set forth in claim 1, in which said logical circuit comprises first and second AND gates having each two inputs and two outputs, the two inputs of the first AND gate being connected to the front output of the first multivibrator and to the back output of the second multivibrator, respectively, the two inputs of the second AND gate being connected to the back output of the first multivibi'ator and to the front output of the second multivibrator, respectively, whereby the signals occurring at the outputs of both AND gates have a duration equal to the time interval elapsing between two signals emitted by said first and second detectors, means to which the output signals of said AND gates are applied, said means being adapted to control the energization of a servomotor in one or the other direction according to which output signal from the AND gates is present.

3. A device as set forth in claim 2, wherein one of the multivibrators is monostable and the other is bistable,

8 the bistable multivibrator comprising a resetting input, the back output of said monostable multivibrator being connected to the resetting input of said bistable multivibrator.

4. A device as set forth in claim 3, wherein means are provided for varying the resetting time-lag of said monostable multivibrator as a function of the duration of the cycle, that is, of the linear velocity of a printed size.

5. A device as set forth in claim 4, wherein said means for varying the resetting time-lag of said monostable multivibrator comprises a time-constant circuit and a point subjected to a biasing voltage subordinate to the cycle duration and to which said time-constant circuit is connected.

6. A device as set forth in claim 2, comprising an integrating amplifier to which the outputs of said two AND gates are connected, and an electromagnet controlling the application of pressure to the printing cylinder, said electromagnet being connected to the output of said integrating amplifier.

References Cited in the file of this patent UNITED STATES PATENTS 2,230,715 Cockrell Feb. 4, 1941 2,289,737 Sorkin July 14, 1942 2,448,292 Barber Aug. 31, 1948 2,549,605 Huck Apr. 17, 1951 2,583,580 Ludwig Jan. 29, 1952 2,866,407 Hackel et al Dec. 30, 1958 2,881,377 Apa et a1 Apr. 7, 1959 2,890,329 Lebenbaum June 9, 1959 2,897,363 Gorgas July 28, 1959

Claims

1. A DEVICE FOR AUTOMATICALLY PRAADJUSTING DIFFERENT ELEMENTS OF A PRINTING MACHINE, WHEREIN A WEB OF PAPER OR SIMILAR MATERIAL TRAVELS THROUGH CONSECUTIVE PRINTING APPARATUS, WHICH COMPRISES A PRELIMINARY MARKING DEVICE FOR APPLYING ON SAID PAPER WEB, PRIOR TO ITS PASSAGE THROUGH THE FIRST PRINTING APPARATUS, FIRST REFERENCE MARKS DISPOSED AT REGULAR INTERVALS CORRESPONDING TO THE PRINTED SIZE, EACH PRINTING APPARATUS COMPRISING A FIRST DETECTOR DISPOSED IN THE PATH OF SAID WEB AND ADAPTED TO EMIT A FIRST SIGNAL WHEN SAID FIRST DETECTOR READS THE PASSAGE OF A FIRST REFERENCE MARK CARRIED BY SAID WEB, AND A SECOND DETECTOR EMITTING ANOTHER SIGNAL WHEN SAID SECOND DETECTOR READS THE PASSAGE OF A SECOND REFERENCE MARK CARRIED BY THE PRINTING CYLINDER OF THE APPARATUS, SAID SECOND REFERENCE MARK BEING FORMED IN THE MARGINAL PORTION OF SAID PRINTING CYLINDER, SIMULTANEOUSLY WITH THE CYLINDER ENGRAVING, SAID FIRST AND SECOND DETECTORS BEING DISPOSED AT THE SAME RELATIVE POSITIONS IN THE DIFFERENT SUCCESSIVE PRINTING APPARATUS, A COMPARATOR COMPRISING A FIRST MULTIVIBRATOR AND A SECOND MULTIVIBRATOR HAVING EACH AN INPUT, A BACK OUTPUT AND A FRONT OUTPUT, SAID FIRST AND SECOND SIGNALS EMITTED FROM SAID FIRST AND SECOND DETECTORS BEING RESPECTIVELY APPLIED TO THE INPUTS OF SAID FIRST AND SECOND MULTIVIBRATORS, MEANS FOR RESETTING BOTH MULTIVIBRATORS DURING EACH CYCLE, A LOGICAL CIRCUIT CONNECTED TO THE OUTPUTS OF SAID FIRST AND SECOND MULTIVIBRATORS AND DELIVERING AT ITS OUTPUT A PULSE THE DURATION OF WHICH IS A FUNCTION OF THE POSSIBLE PHASE SHIFT EXISTING BETWEEN SAID FIRST AND SECOND SIGNALS AND THE SIGN OF WHICH DEPENDS ON THE ORDER IN WHICH SAID FIRST AND SECOND SIGNALS OCCUR AT THE INPUT OF SAID COMPARATOR, AND A SERVOMOTOR CONNECTED TO THE OUTPUT OF SAID COMPARATOR AND ADAPTED TO CONTROL THE DECELARATION OR THE ACCELERATION OF SAID PRINTING CYLINDER, WHEREBY THE ADJUSTMENT OF EACH PRINTING APPARATUS TAKES PLACE AUTOMATICALLY WHEN A PAPER WEB IS INTRODUCED INTO THE PRINTING MACHINE DUE ONLY TO THE COMPARISON OF THE CONSECUTIVE REFERENCE MARKS CARRIED BY THE WEB AND OF THE MARK CARRIED BY THE PRINTING CYLINDER.