FR2522863A1 - METHOD AND APPARATUS FOR RECOGNIZING TRACKING MARKS FOR POSITIONING A READING WINDOW - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS AND A DEVICE FOR RECOGNIZING LOCAL MARKS FOR POSITIONING A READING WINDOW IN A MACHINE FOR PROCESSING A BAND MATERIAL. THE DEVICE INCLUDES TWO READING HEADS 30 AND 31 CONNECTED BY AN AMPLIFIER 32 TO AN ANALYSIS DEVICE 33 INFORMATION READ ON BAND 2 PASSING ON A SERIOUS CYLINDER 38. AN ANGULAR ENCODER 37 TAKES THE ANGULAR POSITION OF THE CYLINDER 38 AND TRANSMITS IT TO THE ANALYSIS DEVICE 33 WHICH, FROM CASE IN CASE, ENTERS IT INTO A MEMORY 51. THE DEVICE 33 ALSO EMITS A SIGNAL 36 TO COMMAND A PLAYER 41 WHICH CAUSES A POSITIVE OR NEGATIVE ELONGATION OF THE BAND 2. FIELD D 'APPLICATION: POLYCHROME PRINTING ON STRIPS.

Description

The present invention relates to a method and a device for

  recognition of registration marks for positioning a reading window in a machine

  processing a strip material.

  The processing of a web material, for example, the printing of a color image on a web continues with the aid of printing units placed one on the other.

  after the others The superimposition of the images corres-

  each printer group leads to obtaining a color image, as they are known, for example in calendars, posters, flyers, etc. To achieve this result, all printed images

  each printing group must be exactly

  that is to say, to be in register with each other To do this, each shot mounted on a cylinder

  printer has one or more registration marks.

  This or these marking marks will refer to the paper to be printed and this in the color corresponding to the printing group that will ink the picture It will suffice, later, to match all the registration marks printed by the different printing groups for have the assurance that the superimposition of the images is correct The setting in registration thus requires a first operation, the detection of the mark of registration on the printed paper, and a second operation, the possible correction of the error of marking the correction of the tracking error is therefore related to the detection of the

  mark of identification The current devices that are con-

  is born to detect the registration marks use

  usually read heads placed so as to observe

  When the tape is scanned, the reading heads are triggered for a certain period of time, generally determined by means of an arrangement of electric or magnetic cams acting as phase selectors. To set such devices, the operator stops the printing press when the registration marks are at the desired location relative to the read heads and then he positions the electric cam, so that it produces, with each rotation of the cylinder, two pieces of information representing the beginning and end of a reading window, within which the registration mark will be located. Such an installation is described in Swiss Patent No. 548 933 of 29 January 1974. A second device based on the one that comes to be described operates as follows: when stopped or running slowly, the operator visually detects the registration marks, then, when the markers are in the desired position, it presses the control button of an electronic storage unit of the position of the registration mark The printing press is then restarted normal and at each turn of the printing cylinder, the memory will recall the position of the registration mark, which will allow its detection by the

reading.

  A third device, mounted on the read heads, allows the detection of the transverse length of the registration mark by means of several photodiodes placed linearly in the direction of the length of the registration mark, so that the photodiodes of each end of the series are placed so as not to detect it, but a free space Thus, if the photodiodes placed in the center of the mark detect

  an impression at the same time as the photodiodes of the

  mites detect a free space, we will be assured that it is a registration mark This in case o, before and after the detection of the printing, the photodiodes have detected a white space of a length determined Detection of white spaces before and after a registration mark can be likened to recognition of a registration mark When all these conditions are met, the place where the mark is located is stored in memory and a window is generated there. at each turn of the printing cylinder, and the reading head of the registration mark will be activated at the appearance of this window This system allows the detection of the mark

  when the printing press is in operation.

  Such a device is described in the French patent

No 1 470 054 of 9 May 1967.

  The devices described above have several

  Disadvantages The first device described requires that the press be stopped for adjustment Regardless of the loss of time thus imposed, it must be taken into account that it is exposed to a collage of the tape of

  paper against the printing cylinder which will probably be followed

  a rupture of the band at the time of delivery.

  machine, which will result in an additional stop

of production.

  The second device presents, meanwhile,

  the disadvantage of introducing the reflex factor of the opera-

  to press at the desired moment on the control of the registration unit of the registration mark, or

  if the solution "stopped press" is chosen, the disadvantages

  will be the same as those recorded for the first device. The third device eliminates the

  disadvantages presented by the two examples above.

  However, for this purpose, this provision uses in

  combination of a conventional reading head and a

  special positive containing additional photodiodes.

  This procedure makes the device more complicated and moreover difficult. Moreover, the device makes it possible to recognize an impression corresponding to a registration mark.

  but is unable to discern which print groups

  the origin of the detected registration marks.

  The object of the invention is to provide a recognition mark recognition device for positioning a reading window, which is simple and capable of suppressing

  the disadvantages mentioned above.

  The invention is defined by the claims

  1 and 2 The appended drawing shows, by way of example, an embodiment of the object of the invention, in which: FIG. 1 is a schematic side view of a multi-color printing press; Figures 2a, 2b and 2c show print reading cases;

  FIG. 3 is a schematic view of a device

  for the recognition of marking marks; and FIGS. 4 and 5 show the evolution of the images of the impressions detected during the period of

  recognition of registration marks.

  Figure 1 is a schematic side view of a printing press in several colors; in the

  In this case, it is a four-color print.

  The printing press 1 is working on a strip 2 of paper

  or cardboard from a reel 3 placed on a carrier

  Reel 4 The web 2 is fed to the printing unit 5 via an input group 6 The yellow color will be assigned to the first printing unit 5 The web 2 then passes through the printing units 7, 8 and 9 which will print respectively the red color for group 7, the blue color for group 8 and the black color for group 9 The strip 2 is then rewound or cut into sheets, or processed by another forming means, for example, cutting blanks folding boots, etc. Each printing group is combined with a dryer

  13 to prevent smudging when rewinding or

  The rewinding of the web 2 takes place on a reel 10 mounted on the bot- tle 11 In order to correct the misregistration error between the colors of the different printing units, each of them is equipped with a walkman 12

  controlled by the tracking control unit (not shown

  sent) mounted on the printing press.

  FIGS. 2a, 2b and 2c show print reading cases FIG. 2a shows the strip 2 of paper or cardboard to be printed This strip 2 moves in the direction of the arrow 14 and the read heads (not shown) are placed on the paths 15 and 16 dashed lines The impression of the image on the strip is represented by the flat plates 17 and 18, and the registration mark by the rectangle 19 FIG. the strip 2 on which are printed the dishes 20 and 21, and two strips 22 and 23 These two strips 22

  and 23 are located between the two dishes 20 and 21 and,

  that they present between them and between said dishes

  and white spaces, they could be

  Marked by the read heads on the runways 15 and 16, Figure 2c also shows the strip 2 carrying the impressions 24 and 25 between which marks 26, 27, 28 and 29 are arranged which are not visible. necessarily all marking marks which can be used on the printing group concerned, in

  In this case, the printing group 8 In the example selected

  if, only mark 29 is the mark of identification of the group and will be recognized as such, as will be seen

  further, by the device according to the present invention.

  It will define the location of the read window 61.

  In order to recognize the registration marks, it is necessary to analyze the strip 2 moving in the direction indicated by

  arrow 14, so as to determine the zones in the-

  which such marking marks may appear.

  For this purpose, two read heads 30 and 31 (see FIG. 3) connected to an amplifier 32 are used.

  output values of the amplifier 32 are then introduced

  The signal 34 will be used to order the angular encoder 37 connected to the engraved cylinder 38 of FIGS.

  detect the angular position of the latter, when the information

  The readings given by the read heads 30 and 31 will indicate that there is a possible zone for detecting registration marks. The angular encoder 37

  transmit a detection signal 39 which will be returned to the

  Analysis device 33 The analysis device will then produce a control signal 36 which will be transmitted to the motor 40 of the player 41, via the control circuit 42. The motor 40 is arranged so as to be able to turn in both directions. and it is coupled to a screw 43 which acts

  on a bearing 44 supporting the roller 45 of the player 41.

  _ ,; ,, i; u5 The bearing 44 is guided during its movement with the aid of the slides 46 For the simplification of the drawing, only the slides 46 located on the left side, with respect to the direction of travel of the strip 2 of the machine, have been shown and it is obvious that the other end of the roller 45 is also supported by a bearing in which engages the same screw as the screw 43 These two screws are interconnected by connecting members (not shown) which may include, for example, chain wheels and a chain allowing the same rotation

  of the two screws The player 41, having been moved vertically

  in one direction or the other, will create, between the two points 47 and 48 of the strip 2, a positive or negative elongation thereof. Thus, the registration mark having been printed by the engraved cylinder 38 will be offset compared to the marks previously printed on tape 2,

  for example by the engraved cylinder 49 or by another cylinder

  dre engraved from a previous printer group The read heads 30 and 31, at the same time they will transmit the information of a possible brand detection zone

  locating, will also transmit the indication of the pre-

  The reader will gather information from the read heads 30 and 31 and

  treat them in such a way as to control the position of

  If, during this operation, it appears that one of the marks is offset with respect to the other, the internal circuits of the analysis device 33 will emit a storage signal. detection signal 39, which will be transmitted to the

  memory 51 The detection signal 39 of the angular position

  1, the angular encoder 37 will transmit, at each rotation of the engraved cylinder 38, the detection signal 39 to the analysis device 33 which, by another internal circuit, will control the action of the mark detection zone having been memorized. of a register mark read head connected to a registration correction device (not shown) If, during the processing operation of the data supplied by the read heads 30 and 31, in

  the analysis device 33 no difference between the differences

  If the detected marks do not appear, the internal circuits of the analysis device 33 will not emit a storage signal 35, and therefore the detection signal 39 of the angular position of the mark detection zone will not be detected. The analyzer device 33 also includes a circuit which allows it, depending on the position of the recognized registration mark, to determine which engraved cylinder it relates, and another circuit to create around the mark.

  recognized recognition, a reading window 61.

  FIG. 4 represents the image of the impressions made on the strip 2 in a corresponding zone 50

  to an eventual zone of detection of registration marks.

  Area 50 presents the conditions required for the existence of registration marks, that is to say that there is observed a printed area 52 followed in the direction of the arrow 53 of a first white space 54, of a first impression 55

  of a width I which may correspond to a mark of repetition

  a second white space 56, a second impression of

  57 of a width 11 may also correspond to a registration mark, a third white space 58 and a new printed area 59 The read heads and 31 (see Figure 3) having communicated this information

  to the analysis device 33, the latter has commanded the

  If, during the next reading, the read heads 30 and 31 detect the same arrangement of the different prints, the analysis device 33 will not emit a storage signal 35, which will mean that the first and second impressions 55 and 57 only

are not marks of identification.

  Figure 5 also represents the image of

  impressions in an area 60 corresponding to a possible area

  This zone 60 had, in its passage in front of the read heads 30 and 31, the same configuration as that of the zone 50 described in FIG. 4. However, after the player 41 has been moved on the the order of the analysis device 33, it appears that one of the prints 55 has remained in a position 55 ', while the position of the other prints and 57 has been modified The information transmitted by the read heads 30 and 31 to analysis device 33 are therefore different from those previously transmitted,

  this will emit the storage signal 35 and the location

  the reading window, ie the read window 61, will be defined and stored, and then recalled automatically

  at each turn of the engraved cylinder 38 (see Figure 3).

Claims (5)

  A method of recognizing registration marks for positioning a reading window in a machine for processing a web material, characterized in that readings on a moving web are read after it has passed on an engraved cylinder (38) of a treatment group, that this reading is analyzed, that according to the printed and unprinted spaces of the strip (2) at least one zone (50) of presence is determined possible marking marks, that, this zone (50) of presence of the registration marks being fixed, causes a positive or negative elongation of the strip (2), which is controlled, after positive elongation of the strip (2), the relative position of the marks located in the zone (50) of presence of the possible registration marks, that, if the marks have an offset relative to each other, the angular position of a cylinder is memorized engraved (38) having printed the said marks so as to create a reading window (61) and then recall, at each revolution of the engraved cylinder (38), the angular position   stored in said engraved cylinder (38).   Process according to Claim 1, characterized in that a positive or negative elongation of the web (2) between two points (47, 48) thereof is obtained and in that the zone (50) is determined. ) of presence of the possible marks according to the presence of a first printed area (52) followed by a first area without printing, a second printed area (55), a second area without printing, a third printed area (57), a third unprinted area and a fourth area printed (59).   3 Apparatus for implementing the method according to claim 1, characterized in that it comprises means for observing the surface of the strip (2), means for amplifying the results of the observation of said strip (2), means for analyzing the results of said observation of the web (2), means for detecting the angular position of an engraved cylinder (38) acting on the web (2), means for storing cases in the case of the angular position said engraved cylinder (38),   means for causing a positive or negative elongation   tif of the strip (2) and means for controlling the latter. 4 Device according to claim 3, characterized in that the means for observing the surface of the strip (2) consist of two read heads (30 and 31) arranged opposite the strip (2) on two courses   (15 and 16) and that the means for amplifying   results of the observation of the said band (2) consist of by an amplifier (32).   Device according to Claim 3, characterized in that the means for analyzing the results of said observation consist of an analysis device (33) comprising circuits for processing the information coming from the read heads (30 and 31), circuits for controlling or not storing the information provided by an angle encoder (37), as well as circuits for generating a control signal (36) of a walkman (41).   6 Device according to claim 3, characterized in that the means for detecting the angular position of the engraved cylinder (38) consist of an angular encoder (37) connected to the analysis device (33) and in that   that the means for memorizing the angular position of the cy-   engraved liner (38) are constituted by a memory (51)   connected to the analysis device (33).   7 Device according to claim 3, characterized in that the means for causing a positive or negative elongation of the strip (2) consist of a walkman (41) actuated by a motor (40) controlled by a control circuit (42) driven by a control signal (36)   transmitted by the analysis device (33).