US3068787A

US3068787A - Device for checking longitudinal registration on machines for performing repetitive operations on a continuous band

Info

Publication number: US3068787A
Application number: US110847A
Authority: US
Inventors: Dall Oglio Giorgio; Viale E Caldara; Carnevali Giberto
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-05-18
Filing date: 1961-05-17
Publication date: 1962-12-18
Anticipated expiration: 1979-12-18

Description

18, 1962 e. DALLOGLIO ET AL 87 DEVICE FOR CHECKING LONGITUD L REGISTRATION ON MACHINE PERFORMING REPETITIVE OP TIONS ON A CONTINUOUS BAND Filed May 1961 2 Sheets-Sheet 1 1952 G. DALLOGLIO ET AL 3,

DEVICE FOR CHECKING LONGITUDINAL REGISTRATION ON MACHINES FOR PERFORMING REPETITIVE OPERATIONS ON A CONTINUOUS BAND Filed May 17, 1961 2 Sheets-Sheet 2 Sttes 3,068 787 DEVICE FOR CHECKINGIONGITUDINAL REGIS- TRATION ON MACHINES FOR PERFORMING REPE'IITIVE OPERATIONS ON A CONTINUOUS The present invention has for its subject a system for regulating the longitudinal positional setting or registration on machines used for performing repetitive operations on a continuous band, such as, for example machines used for printing by superimposing monochromatic images (of the rotogravure or similar type). The regulation of the longitudinal registration consists in this case in adjusting the position of the individual monochromatic images so as to obtain a very high degree of precision of superimposition between the several images--which must normally be correct to the tenth of a millimetre.

In the present art, the relative positions of two monochromatic images from two printing rollers are checked by measuring the time lapse between the reading of a reference mark forming part of one image printed by one roller, and the reading of a control mark forming part of the image printed by a subsequent roller or engraved directly thereon: if said second mark is printed on the paper, then the check is of the paper-to-paper type, and if it is engraved on the roller, the check is of the paperto-roller type.

In the present state of the art, said time lapse is measured and a system of any kind is used to determine the speed of the machine at the instant of measurement; given the time lapse and the machine speed, the space corresponding to the error can be deduced therefrom; this may be termed the analogue type of measurement inasmuch as it has all the characteristics of systems known by this name in the art of electronic computers.

An object of the present invention is to provide a system which can be defined as digital: this system, which comprises an impulse counter, is based on the counting of the number of impulses emitted in the interval of time which elapses between the two respective readings of a reference mark and a control mark, by means of two reading heads; a system is then provided which is designed to correct the error in accordance with the number of impulses counted.

Two embodiments of the present invention will now be described with reference to the accompanying drawing wherein:

FIG. 1 shows schematically an example of a machine for printing on a continuous band by means of rollers;

FIG. 2 shows schematically an example of the device according to the present invention;

FIG. 3 shows schematically a second example of a device according to the invention;

. FIG. 4 shows schematically a detail vice in said FIG. 3;

FIG. 1 shows a diagram of the printing machine wherein the various component parts of the machine are visible.

The band of paper to be printed, indicated by the numeral 2, unwinds from the reel indicated by the numeral 1, passes through a set of transporter members and is brought into contact with the printing rollers indicated by the symbols C to C Said rollers C to C are caused to rotate by means of a main motor 3 on whose shaft 4 are keyed the gears indicated by the symbols A to A these are respectively in mesh with the gears indicated by the symbols B to B relating to the de- Via Moscova 40/5; Alfonso de Mar- 3,058,787 Patented Dec. 18, 1962 2 The first roller C is driven directly from shaft 4; for each of the remaining rollers from C to C there is provided a differential unit coupled to a correcting motor, thereby per mitting the rollers to rotate independently from the others in order to correct their respective positions. Said differential units are indicated by the symbols S to S and the related correcting motors by the symbols M to M Errors occurring in the superimposition of the images can be corrected not only by means of said correcting action on the rollers, but also by varying the length of the section of paper band 2 between the two rollers which respectively print the two images with said error of superimposition. To this end, some of the transporting members relating to the sections of hand between the rollers, are made movable.

In the same FIG. 1 the reading heads L to L directed to the band of paper, and the reading heads N to N adapted to read from the rollers themselves, are also in dicated.

With the paper-to-paper type of check, that is where there are two reading heads checking the relative positions of two marks printed on the paper respectively by one roller and by a subsequent roller C to C in respect of which the check is being performed, the two reading heads corresponding to said roller C to C to be checked are both incorporated in the device L to L this device, as can be seen from said FIG. 1, is in fact placed after the related roller C to C With the paper-to-roller type of check, that is'where two reference marks are read, one printed on the'paper by a roller and the other engraved on a subsequent roller C to C to be checked, one reading head (not shown in the drawing for the sake of simplicity) is provided before said roller C to C and another reading head N to N is also provided for the purpose of reading said mark engraved on roller C to C Lastly in FIG. 1 there is shown an impulse or signal generator 5 which can be a transparent disc on'which radial marks have been traced. The marks are sensed or read by a photoelectric system while they are being rotated by the main shaft 4. A device of this kind is sold by Wel Gurley of Troy, New York, under Model 8603.

A magnetic device similar to the photoelectric system can also be used.

FIG. 2 shows a diagram of a device for correcting-the error occurring in the superimposition of two images one on the other.

In FIG. 2 there can be seen the impulse generator 5 which is directly connected to the driving shaft 4; the numeral 15 is a schematic representation of the mechanical connecting member between said shaft and said generator; in this example the frequency of the impulses depends on the speed of the machine.

Since for a given angular movement of the driving shaft 4 there is a corresponding given linear movement of the band, that is, for every revolution of the shaft a constant length of band is advanced, and since generator Sis connected directly to shaft 4,it follows that impulse generator 5 generates a constant number of impulses for unit'length of paper, irrespective of the'speed of advancement of' the paper itself. I j

In the present example, two

reading heads

6 and 7 are provided which are each capable of supplying an impulse whenever a mark (reference or control) passes there-.

under. One of the two heads, head 6 for example, serves as-a reference head, while the other, 7 serves as a control head. In this'example head 6 is deemed to be the one which readsthe position of the referencemark of the image printed on the paper band-2 before "the roller in respect whereto the check is to be performed; while head 7 is deemed to be the one which -readsthe position of the' control mark which can be on the roller itself with regenerator 5.

spect whereto the check is to be performed: we have thus the paper-to-roller type of check, the error being read before the roller being checked prints its monochromatic image. Said check mark may also, as mentioned hereinabove, be read on'the monochromatic image printed on band 2 of said paper by the roller to be checked, and

in this case we have the paper-to-paper type of check, the error being read after printing by the roller being checked.--

In both of the caseshereinabove referred to, that is paper-to-roller and paper-to-paper' checking, the positions viously printed by the other roller (the reference roller); similarly,

if the impulse coming from head 7 is behind that coming from head 6, then the error will be one of retardation.

Each of the two

reading heads

6 and 7 is connected to the starting circuit 8 shown on page 57 of the Handbook of'Electronic Control Circuits, McGraw-Hill Company,

Since the correction involves a movement which'is,

measurable in units of length, it is possible-to generate an impulse, by means of device 13, for each unit length of correction. 7

Besides this it follows from what has been stated that said counter also counts an impulse for each unit of error, said impulse being emitted by generator 5; thus, by inn posing the condition that the length corresponding to each a error impulse (emittd by generator 5) be equal to the length corresponding to each correction impulse (emitted by device 13), it will happen that if the counter has counted 12 impulses, corresponding to a given error e,

New York, 1959, of high-speed electronic counter 10 r such as that shown on pages 60 and 61 of the Handbook of Electronic Control Circuits, McGraw-Hill Company, New York, 1959, so that the first impulse which arrives from a head (6 or 7) switches in said starting circuit 8,

while the secondimpulse cuts it out. 7

During the time when starting or gate circuit 8 is in operation, that is in the interval between the two impulses,

counter 10 counts the impulses generated by the impulse It should be noted that the impulse generator continuallygenerates impulses for the solereason that shaft 4 of the machine is in motion, whether such impulses are counted or not. .However, the impulses emitted by the generator are counted during said interval, and the content of the counter at the end of the counting process, that is after the emission of the second impulse by the heads, determines theamount of the error., 7

Said counter 10 is also connected to two error correcting devices respectively for advancement 11) and retardation (12). The two

heads

6 and 7 are al-soconnected to a sign detectori9 whichis in turn connected to said devices 11 and12. 1 t

It follows that, when counter 10 has finished counting, the number of impulses corresponding to a' given error,

' the counter itself causes one or other of the two

devices

11 and 12 to come into action; to be precise, the

device which is selected by the sign detector) will comeinto action according as' to whethersaid sign detector receives'the. signal first from head 6 or from head 7."

If, for-example,'head 7 is the first to emit a signal, then ,there is an 'errortof advancement that is,;the roller being rotated too fast. J a a In this case, since the impulse emitted by head 7 precedes that emitted'by head 6, sign detectorz 9 will select correction device 12, whichmeans thatsaid device will t occur that the correction device will be halted before the when device 13 has emitted n impulses, a correction will have been made which istalso equal to e. Device 13, through the n impulses emitted, will have zeroized the contents of counter 10 and hence the latter will'cease to correct, that is it will halt device 11' or 12 which has carried out the correction.

In practice it may be. useful to cause the correction to stop before the contents of the counter are at zero, that is when device 13 has emitted a' number r of impulses fewer than said number n, which means that it can be arranged for counter 10 to cause the correcting device (11 or 12) to stop when the contents of the counter are equal to n-r. I

In this case, since said number r of impulses is smaller than the number n of error impulses and hence corre sponds to a lesser correction of the error itself, it will correction itself has been completed: in this manner any inertia inherent in the mechanical correction device is taken into account andsotthe correction itself, although it causes the correction device to be halted, will IJOllCthBr.

less be completed, that is it will reach the there is complete annulment of the erro point at which j In the example hereinabove described, said generator of impulses 5 should be assumed to be a the whole machine, whilst, on the other hand a device for error reading and correction is provided for each roller starting from roller C that'is, a device comprising the single one serving reading heads, the counter, the sign detector, the eorrec-'

tion devices

11 and 12 and the control device 13; is repeated for each of said rollers.

In the second embodiment of the device according to the invention, illustrated in FIG. 3, there are again as in; t the previous case, two reading heads 6' and 7', a sign ne tector 9",- an advancement correction device 11', a retar dation correction device 12' and a control device 13';

similarly also, a counter 10' with relatedffstarting circuit 7 8' is provided. The members indicated lar functions to those of the p As variants to the device of the previous eiiampleta constant frequencyimpulsegenerator 18 is provided, that I 3 is one whose impulses are independent of the speed of shaft 4 of the machine such as a'conventional multivi comejinto action after theemission of theimpulsefrom a head. 6, that is when counter" 10 has finished counting,

" If on the other hand, head-6 emits its impulsefirst',.the

at :the end of the count. ,A fcontrol device 13 Lsimilar1to vicewhen the correction has reached a'valuejfequal to a the value of the error 'or. dependent thereon; said device 13 is mechanically connected to devices 11 and12 through a connection representediby 14 and is actuated thereby;

counter 10.

' advancement correction device l l willcome' into action a .will more clearly brator; there are also provided as variants fromfthepre' j vious" device, a third reading head 16, a second counter 19similar to counter 10' with related starting circuit 17 similar to starting: circuit 8', andfa device 20 whichi is bygdashednumerals havesirnir, V evious example which are t 7 indicated by undashed numerals.

designed to find, the ratio between the numbers 0 nn-t pulses counted respectively by

counters

10 and 19,;as appear hereinafter. As inthejprevious example, the two heads 6' and 7" read respectively 'the 'reference'mark and the control markfthefirst reading impulse'generator 5 is also provided for the purpose of head (6' or Tysets 0E circuit -acting'on counter 10 in order to stop the correction-de-t counting bycounter 10'; the second thus starting offth' val between the two reading cuts 05 the: t j i counting. l The number-of impulses counted in the inter readings depends not only 56a 'the'j error e but also, in this case, on thespeedtof advance ment of the paper band 2, that is on the speed of'shaft 4,; V

and, to be'precise, it"is inversely proportionalto said.

speed: in'the present example in fact, the impulse gen a erator 13 is independent of said shaft and the frequency of the impulses is constant.

The third reading head 16 is situated after reading head 6 at a fixed distance therefrom, indicated by the arrow 1 in FIG. 4; the symbols s and .9 indicate respectively, for illustrative purposes, the reference mark and the control mark, both of which are on the band of paper 2, after printing by the two rollers; arrow F indicates the direction of advancement of the band itself.

The two marks s and S; are separated, in the direction of the length of the band, by a distance 6 which represents the printing error.

It follows from what has already been said in connection with the relative position of

heads

6 and 16, that said head 16 also reads the reference mark s after this mark, having already been read by head 6', has traversed the space 1. Besides the functions which have already been described, said head 6, as in the previous example, also has the function of controlling the starting circuit 17 of counter 19 by means of an impulse emitted when reference mark s passes under said head; thereafter, head 16, when reading mark s passing below it, emits an impulse for the purpose of stopping said starting circuit 17. In this manner counter 19 counts the number of impulses emitted by generator 18 in the interval between the two impulses emitted by heads 6 and 16' respectively. The number of impulses counted by counter 19 is also inversely proportional to the speed of shaft 4, that is to the speed v of advancement of the paper band 2.

There are thus two counters 1i) and 19 which count the two numbers n and n of impulses emitted respectively in the interval between the two impulses emitted by heads 6' and 7, and in the interval between the two impulses emitted by heads 6' and 16'.

Now each of said numbers, considered as variable, is directly proportional to the amount of advancement of the band in the interval under consideration, and inversely proportional to the speed v of this advancement, or to be more precise, the'two numbers n and n' are given by expressions of the type:

where K is a constant. Consequently the ratio n/n' is given by n/n=/l, that is, whilst the two number of impulses n and n depend on the speed and consequently on the respective time intervals during which the impulses are counted by counters 10' and 19, said ratio between the two numbers of impulses does not depend on the speed, nor therefore on the time, but simply on the error (1 being a constant).

The device 20 which is connected to counters 10' and 19 works outsaid ratio and is used to control the

correction circuits

11 and 12 as in the previous example; in particular, this device will act as a counter and behave in relation to the correction system in the same manner as counter 10 behaved in the previous example.

Rollers C to C can be checked by first comparing roller C with roller C then roller C with roller C and so on; each of rollers C to C can also be compared with the first roller, i.e. roller C In this second example also, illustrated in FIG. 3, there is a single impulse generator 13, whilst a device is provided with members for reading and correcting the error at each roller, starting from roller C We claim:

1. A control device for controlling the positional relationship when superimposing two monochromatic images printed one after the other on a paper band comprising means for moving said paper band past printing members, at least two reading heads, one reading head for reading a reference mark passing thereunder and the other reading head for reading a control mark passing thereunder and which is to be made coincident with said reference mark, a gate circuit operatively connected to and for receiving impulses from each reading head, main pulse generator means for generating pulses at a predetermined frequency, correction means opera tively connected to said moving means, a second pulse generator means operatively connected to said correction means for generating pulses in correspondence to the operation thereof, pulse counter means operatively connected to said gate circuit and pulse generators, said gate circuit controlling said pulse counter means for counting the pulses coming from said pulse generators only when there is a difference between the reference and control marks read by the reading heads, a sensing means, operatively connected between said reading heads and said correction means to select the proper correction to be applied to said moving means in accordance with the reference and control marks being read by said reading heads, and means connecting said pulse counter means to said correction means to stop operation thereof when the pulses from said second pulse generator means to said pulse counter means have reached the corrected valve.

2. A control device according to claim 1 in which said main pulse generator means is operatively connected to said moving means.

3. A control device for controlling the positional relationship when superimposing two mono-chromatic images printed one after the other on a paper band comprising means for moving said paper band past printing means, at least three reading heads, a first reading head for reading a reference mark passing thereunder, a second reading head for reading a control mark passing thereunder and a third reading head spaced from said first reading head and for reading said reference mark passing thereunder, said reference mark to be made coincident with said control mark, a first gate circuit operatively connected to and for receiving impulses from said first and second reading heads, a second gate circuit operatively connected to and for receiving impulses from said first and third reading heads, a first pulse generator means for generating pulses at a predetermined frequency, correction means operatively connected to said moving means, a second pulse generator means operatively connected to said correction means for generating pulses in correspondence to the operation thereof, first pulse counter means operatively connected to said first gate circuit and first pulse generator means, said first gate circuit controlling said first pulse counter means for counting the pulses coming from said first pulse generator means only when there is a difference between the reference and control marks read by said first and second reading heads, a second pulse counter means operatively connected to and for receiving pulses from said first pulse generator means and second gate circuit, said second gate circuit controlling said second pulse counter means for counting the pulses from said first pulse generator means, a third pulse counter means operatively connected to and for receiving pulses from said first and second counter means and said second pulse generator means, a sensing means operatively connected between said first and second reading heads and said correction means to select the proper correction to be applied to said moving means in accordance with the reference and control marks being read by said first and second reading heads, and means connecting said third pulse counter means to said correction means to stop operation thereof when the pulses from said second pulse generator means to said third pulse counter means have reached the corrected valve.

4. A control device for controlling the positional relationship when superimposing two images printed one after the other on a printing medium comprising means for moving said printing medium past printing means, at least two reading heads for reading reference and control marks respectively, gate means for receiving impulses read by said reading heads, selecting means for receivmeans connecting said counter means to said correcting means to stop same when the pulses from said generator means have reached the corrected valve represented by coincidence between the reference and control marks.

References Cited in the file of this patent UNITED STATES PATENTS Shoults et a1. Mar. 21, 1939 Cockrell Feb. 4, 1941