Abstract:
A system is provided for inspecting a printed image. The system is provided with at least one evaluation unit, a display device and an image scanner. That scanner takes an image that represents, at least partially, a printed image. The copied printed image belongs to a sequence of images printed on a print carrier by a printing machine. The evaluation unit receives data that is correlated to an image which has been taken, and evaluates that data by comparing it with recorded data of at least one preceding image, or with a reference image. The display device is provided with a graphic display surface that is comprised of several areas which are controlled, in a different manner, by the evaluation unit, and which are preferably simultaneously displayed. A first area displays several images, such as the just taken image, the preceding image and the reference image. The second area includes an input field or a control point for adjusting or controlling the evaluation unit or for adjusting or controlling the printing machine.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is the U.S. national phase, under 35 USC 371, of PCT/EP2004/050662, filed Apr. 30, 2004; published as WO 2004/096547 A2 and A3 on Nov. 11, 2004, and claiming priority to DE 103 19 771.0 filed May 2, 2003, the disclosures of which are expressly incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention is directed to systems for inspecting a printed image. The printed image is captured by an image sensor, and is displayed on a display device. The display device forms a multiple part display, some part of which can be used to control a printing press. 
   BACKGROUND OF THE INVENTION 
   A device for detecting printing errors or other errors in a printing press is known from EP 0 554 811 A1. At least two cameras, with different image definitions, are arranged one behind the other at the end of the printing process in the production direction of a web or a sheet and forward their respective output signals to a computer. A monitor and a keyboard are connected to the computer. The camera which is first in the production direction, and which preferably is a line camera, whose image taking is synchronized with the production speed of the printing press, has a coarser definition than the following second camera, which preferably is a CCD area camera. Images of zones of the web or the sheet, which are not imprinted, or which are imprinted in a uniform color, and which are recorded by the camera which is first in the production direction, control the camera which is second in the production direction, shifting it transversely to the production direction. The second camera then no longer systematically detects these zones, but records images of high resolution, of zones in which the camera which is first in the production direction has already detected errors. An image recorded by the first camera or by the second camera can be represented on the monitor and can be compared with a previously entered reference image by operating a keyboard. 
   A system for operating a printing press is known from EP 1 291 767 A2. Two different applications are simultaneously displayed in two differently sized windows of a monitor which is assigned to the printing press. An original of the printer&#39;s copy is represented in one window, and in the other window functions for operating the printing press are displayed. 
   A device for controlling a printing press is known from US2002/0029703 A1. Various types of information regarding the printing process and status information are represented on the monitor of a PC. The control information regarding the printed pages is represented in the form of symbols. 
   A method and a device for controlling or for regulating operational processes of a machine in connection with print technology are known from DE 43 21 179 A1. At least one image-taking device is directed onto the surface of a printed product. The image-taking device sends its information, representing the surface of the printed product, to a control and regulating circuit. A reference image, an actual image and a reference image can be selectively represented either individually, or in partial images on a display screen which is connected with the control and regulating circuit. In the case of an impermissible deviation of the actual image from the reference image detected by the comparison device of the control and regulating circuit, an error signal can be issued. 
   In the technical manual “Offsetdrucktechnik” by Helmut Teschner, 10th ed. 1997, and published by Fachschriftenverlag, Fellbach, ISBN 3-921217-14-8, embodiments of a control console “Heidelberg CPC” are described on pages 10/108 to 10/117. The control console is a part of a computer-supported system for quality monitoring, and for quality control of printed products produced by a printing press. The control console has, inter alia, a plurality of different operating elements in a console or in a keyboard, which keyboard is part of the control console, and is usable for controlling an ink metering system which is arranged in the printing press. The quality control is performed by the use of densitometry or of spectral photometry. The control console provides an option to a pressman for checking print samples which are taken from the running production and to then perform corrections, which are considered to be required, by actuating operating elements of the printing press. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is directed to producing systems for inspecting a printed image. 
   In accordance with the present invention, this object is attained by providing a system for inspecting a printed image. The system has at least one evaluating unit, a display device, and an image sensor. The image sensor records an image. The evaluating unit receives data, which is correlated to the recorded image, and evaluates the data by comparing it to prior images or to a reference image. The display device includes a graphics-capable display area with several window-like sections that can be controlled individually by the evaluating unit. One of the sections shows an image. Another of the sections of the display device has an input field or an operating field for setting and operating the evaluating unit or the press. 
   The advantages which can be achieved by the present invention consist, in particular, in that a system is made available for inspecting a printed image, which system operates during the running production of the printing press, and without the removal of a sample. The parametrization and operating area of the system can be set flexibly and use-relevant, preferably by the use of input aids integrated in the display face, and is comfortable to use. The entire information, that is required by a respective group of users, is displayed clearly structured and openly on the same display face. The system can be easily expanded for performing control and regulation tasks. Shortcomings in quality of the printed images produced by the printing press, and detected by the system during the inspection, are displayed and preferably are logged in. When these images are used, they automatically lead to the identification or to the removal of unsatisfactory print images by the system. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     A preferred embodiment of the present invention is represented in the sole drawing and will be described in greater detail in what follows. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In a greatly simplified representation, the sole drawing shows a display device  01 , an evaluating unit  02 , an image sensor  03  and several printed images  04 , which have been applied by a printing press  06  to an imprint substrate  07 . The printing press  06  is embodied, for example, as a rotary printing press with at least one printing unit. The printing unit has at least one forme cylinder, which is not specifically represented, and which supports at least one printing forme, and a transfer cylinder  21 , which is working together with the forme cylinder. The transfer cylinder  21  is placed against a counter-pressure cylinder  22 , which extends parallel with the axis A of the transfer cylinder. The counter-pressure cylinder  22  can be embodied as a second transfer cylinder, which itself works together with at least one further forme cylinder, which is also not specifically represented assigned to it. In the embodiment represented in the sole drawing figure, the transfer cylinder  21  transfers two printed images  04 , located one behind the other, in the direction of its circumference U, for each revolution. Three printed images  04  are arranged side-by-side, in the axial direction of the transfer cylinder, so that a total of six printed images  04 , for each revolution of the transfer cylinder  21  in its production direction P are applied to the imprint substrate  07 , which substrate  07  is being passed between the transfer cylinder  21  and the counter-pressure cylinder  22  in the transport direction T. 
   The imprint substrate  07  may be, for example, a printed sheet  07  or a printed web  07  of material, and preferably is a paper web  07 . In the course of the printing process, the printing press  06  either prints a sequence of printed images  04 , following each other in the transport direction T, on a continuous web  07  of material, or it prints a sequence of printed sheets  07 , each with at least one printed image  04 , wherein the printed sheets  07  are being transported in the transport direction T. 
   An image-taking area  23  of the image sensor  03  such as, for example, a color camera  03 , and preferably a digital semiconductor camera  03  with at least one CCD chip, is directed onto the imprint substrate  07 . The image-taking area  23  of the image sensor  03  records at least a partial picture of a printed image  04  which is applied to the imprint substrate  07 . For example, the image sensor  03  is arranged at the outlet of the last printing group of the printing press  06 , which last printing group is last in the transport direction T of the imprint substrate  07 . The image sensor  03  detects, for example, the entire width B of the imprint substrate  07 , wherein the width B of the imprint substrate  07  extends transversely to the transport direction T. The image sensor  03  delivers an image, which image can be electronically evaluated, of at least an area of a printed image  04 , but preferably delivers an image of the entire width B of the imprinted imprint substrate  07 , on which at least one printed image  04  has been applied to the imprint substrate  07  along the width B of the imprint substrate  07 . The image sensor  03  is configured as an area camera  03  or as a line camera  03 , which has one optical arrangement  33 , and in particular has a lens  33 , which is suitable for detecting the desired image-taking area  23 . An alternative arrangement of the image sensor  03  is one in which it is not arranged directly at the printing group, but is located at a device or machine, which is not specifically represented, which is located downstream of the printing press  06  and which conveys and/or processes the printed images  04  that are produced by the printing press  06 . 
   The evaluating unit  02 , which, in particular, is embodied as a program-controlled electronic computer installation  02 , and which is arranged, for example, in a control console that is part of the printing press  06 , receives data correlated with the recorded image via a data transfer path  24 , such as, for example, a data line  24 . The image sensor  03  transmits these data to the evaluating unit  02  or at least keeps them ready for call-up. The data, which is correlated with the recorded image, is edited in the evaluating unit  02  in such a way that the image can be represented on a display area  08  of the display device  01 . The display device  01  and the evaluating unit  02  are preferably connected with each other via a bi-directional data transfer path  31  or data line  31 . The image sensor  03 , the evaluating unit  02  and the display device  01  together constitute a system for inspecting at least a portion of a printed image  04  applied to an imprint substrate  07 . However, the functions of this system can also be expanded to include control and regulating tasks, as will be explained subsequently. 
   A memory device  26  is assigned to the evaluating unit  02 , in which memory device  26  data of at least a portion of the images being recorded and/or data regarding a portion of an image previously recorded can be stored. The stored data, at least the data of a specific image, is used as a reference for comparison with data of continuously, actually recorded images. The connection between the evaluating unit  02  and the memory device  26  consists of a bi-directional data transfer path  27 , or data line  27 . 
   It is possible, by the use of a comparison, that is performed in the evaluating unit  02 , of the data of an actually recorded image with the data of a previously recorded image, or with the data of a stored reference image, to determine, in the running printing process, a value, such as, for example, an increase in shading value in successively recorded printed images  04 . It is also possible, for example, to detect, by the use of a comparison, to what extent the registration in successive images exists, in other words to determine to what extent there exists a congruent agreement of the position of the printed image or printing area between recto and perfecting printing, or also between the top and underside, when producing products which are imprinted on both sides. A register can be checked, in the same way, by use of the comparison, to determine the intended exactitude of the individual partial colors when being printed on top of each other during multi-color printing. The increase in shading value, the registration accuracy, as well as the register accuracy, play important roles in multi-colored printing. 
   The printed image  04  can also be judged qualitatively by the use of a recognition characteristic which distinguishes the printed image  04 . Either the recognition characteristic alone, or the printed image  04 , together with the recognition characteristic, are checked by a comparison with a reference image to determine whether the recognition characteristic, or the printed image  04  with the recognition characteristic, belong to a specific class of recognition characteristics or of printed images  04 , and to determine whether the recognition characteristic has a defined geometric contour and/or a specific relative arrangement with respect to at least one further recognition characteristic. These checks are preferably performed with a tolerance for errors, so that the judgment takes place while taking permissible tolerance limits into consideration. 
   It is advantageous if the checks to be made on the printed images  04  are performed in the evaluating unit  02  in parallel routines and therefore, for all practical purposes, are performed simultaneously. The result of a check can be used to trigger an actuating command for use in correcting a deviation which is detected in an actually recorded and checked image from a reference value which is decisive for the check. The evaluating unit  02  can therefore be equipped with at least one output, from which at least one output an actuating command is conducted, via a data transmission path  28 , to an actuating drive  29 , which actuating drive  29  affects the printing operation in the printing press  06 . Such an actuating drive  29  may be provided, for example, in connection with an inking system or with a dampening system, which systems are part of the printing group, a circumferential registration device, a lateral registration device, or to accomplish a diagonal shifting of at least one of the forme cylinders with respect to its assigned transfer cylinder  21 . The output of the evaluating unit  02  can also be used for activating, for triggering or for shutting off an illumination arrangement, which is not specifically represented for the image sensor  03 , such as, for example, a flash lamp. 
   The display device  01  has a graphics-capable display area  08 , which is provided with several window-like sections  09 ,  11 ,  12 ,  13 ,  14 , which can each be differently controlled by the evaluating unit  02 . A first such section  09  selectively shows an actually recorded image, a previously recorded image or a reference image. A second such section  11  has at least one input field  16 ,  17  and/or at least one operating field  18 ,  19  for use in setting and/or for operating the evaluating unit  02  and/or for use in setting and/or for operating the printing press  06 . The system can be set with regard to at least one parameter. A function to be executed by the system can be called up and/or triggered, and/or an actuating command to be issued by the evaluating unit  02  can be entered into the system or can be selected from a plurality of preset actuating commands by use of the input field or fields  16 ,  17  and/or by use of the operating field or fields  18 ,  19 . 
   Because of the display area  08  being structured in sections  09 ,  11 ,  12 ,  13 ,  14 , which can each be operated independently of each other, or which can simultaneously be controlled by the use of different information contents by the evaluating unit  02 , the display area  08  which, may be, for example, a part of a control console which is part of the printing press  06 , is provided with a clear and easily usable operating area, on which operating area it is possible to display at least information relevant to the inspection of a printed image  04 . On the same display area  08 , at least one operating element may be simultaneously provided, at least in one of the sections  09 ,  11 ,  12 ,  13 ,  14 , in order to react to the actually displayed information by the use of at least one command to the system. The command affects the process performed by the printing press  06  in such a way that it counteracts a detected deviation in the inspected image from at least one reference value. For the representation of information on the display area  08 , it is advantageous to employ colors, and in particular to employ different colors for presenting different information. 
   The display device  01  and the evaluating unit  02  can be configured in such a way that actually recorded images are continuously displayed in the first or image display section  09 . As soon as a recorded image indicates that the printed image  04  shown exceeds at least one previously set permissible tolerance limit, with respect to its quality to be checked, the display of this image is frozen, so to speak, in that the display of the continuously recorded images is stopped. In a variation of this embodiment, the display device stops at an image which exceeds at least one of the previously set permissible tolerance limits for at least a length of time, which is preferably adjustable, before the display of the continuously recorded images is again continued with the actually recorded image. The length of time for stopping the display can be 5 to 15 seconds, for example, and preferably is 10 seconds. 
   A printed image  04 , whose evaluated image shows that it exceeds at least one previously set permissible tolerance limit, with respect to its quality to be checked, can be marked by the use of a marking arrangement, which is not specifically represented, which marking unit is connected with the system, and/or the defective printed image  04  can be removed by a conveying arrangement, which is also not specifically represented. The system can be set in such a way that, when it is determined that a permissible tolerance limit has been exceeded, the evaluating unit  02  will automatically trigger the marking of the printed image  04  by the marking arrangement and/or the removal of the printed image  04  by the conveying arrangement. To accomplish this, the evaluating unit  02  issues an appropriate actuating command at its output, for example. The conditions, which are required for triggering this actuating command, can preferably be selected and can be set at the display area  08 . 
   A third section  12  is preferably also provided on the display area  08 . This third section  12  displays at least a designation of the evaluating unit  02  and/or of a job actually being processed in the printing press  06 . It is also possible to show, in this third section  12  of the display area  08 , for example, whether the actual job has undergone a change of its parameters which are relevant to the printing process. 
   The display area  08  can also have a fourth section  13 . This fourth section  13  has at least one menu with a menu structure, which opens, when selected, and which contains at least one function for operating and/or for setting the evaluating unit  02 , and/or for operating and/or for setting the printing press  06 . Thus, the function which can be selected in the fourth section  13  of the display area  08  relates, for example, to the setting up of a new job to be processed by the printing press  06 , or to the processing or to the changing of an existing job. As a function of the selection made from the menu, the second section  11  of the display area  08  sets a fixed sequence of input fields  16 ,  17  and/or of operating fields  18 ,  19  for setting and/or for operating the evaluating unit  02  and/or for setting and/or for operating the printing press  06 . In this way, a user is guided with respect to a function to be set in the system and/or in the printing press  06  in such a way that all of the settings which are required for the desired functions are consistently sequentially interrogated, and wherein a following interrogation requires that the previous interrogation has been answered. 
   In the same way, an image, which was stored in the memory device  26 , can be selected from the menu which can be displayed in the fourth section  13  of the display area  08 . The selected image can be displayed in the first section  09  of the display area  08 . 
   A further function which can be selected in the fourth section  13  of the display area  08  from the menu can, for example, consist of fixing one or several tolerance limits for evaluating the quality of the printed images  04  generated by the printing press  06 , or of taking the system out of operation by use of an orderly switch-off of its functions. The latter preferably can only be performed when the printing press  06  is stopped and after its execution is announced by an appropriate report. In connection with the evaluation of a quality characteristic, for which a permissible tolerance limit is to be fixed, it is advantageous to store a plurality of different sensitivity levels in the evaluating unit  02 , such as, for example, between five and twenty such sensitivity levels, and preferably ten such sensitivity levels. A suitable sensitivity level can be selected and set for the system by use of the menu displayed in the fourth section  13  and/or in the input fields  16 ,  17  and/or in the operating fields  18 ,  19  in the second section  11 . 
   A fifth section  14  can also be provided on the display area  08 . The fifth section  14  shows at least a status of the evaluating unit  02  and/or the printing press  06 . Status indications in this fifth section  14  can, for example, be provided in the form of a pictograph. 
   It is of advantage, in accordance with the present invention, if the display area  08  shows the first section  09  and the second section  11  arranged side-by-side, and at least two of the five sections  09 ,  11 ,  12 ,  13 ,  14 , and preferably all five sections  09 ,  11 ,  12 ,  13 ,  14 , simultaneously. The display area  08  can show the third section  12  at its upper edge, the fourth section  13  below the third section  12 , the fifth section  14  at its lower edge and the first section  09  and the second section  11  between the fourth section  13  and the fifth section  14 , as depicted in the sole drawing FIGURE. Preferably the third, fourth and fifth sections  12 ,  13 ,  14  are each configured in a linear shape. The display area  08  typically permanently displays at least the fourth section  13  and the fifth section  14 . 
   Advantageously, at least the first section  09  of the display area  08  is embodied to be video-capable and in a position in which it is capable of displaying a sequence of several images which follow each other rapidly. Therefore, the first section  09  of the display area  08  is capable of sequentially displaying images of printed images  04  printed on the imprint substrate  07 , or of images of at least portions of the printed images  04  printed on the imprint substrate  07 , which images or portions of images were sequentially recorded by the image sensor  03 . These images or portions of images are displayed in the way in which the printed images  04 , which had been recorded completely, or at least partially, by the image sensor  03 , which is stationary with respect to the printing press, pass the image-taking area  23  of the image sensor  03  at the transport speed of the imprint substrate  07 . An image reproduction frequency of the first section  09  of the display area  08  is therefore at least as fast as an image recording frequency of the image sensor  03 . Thus, in a manner corresponding to the transport speed of the imprint substrate  07 , it is possible to display, for example, five or more printed images  04  per second in the first section  09  of the display area  08 . This movie-like display of the printed images  04  in the first section  09  of the display area  08  has the advantage that, for example, a tendency of the sequentially displayed images to color deviations can be detected very rapidly, even though at a display speed of several images per second, the individual printed image  04  can no longer be discretely inspected by the operators of the printing press. By such a display of a sequence of printed images  04 , it is also detectable in which areas of the sequentially imprinted printed images  04  such color deviations occur, so that the application of color by the inking system can be zonally updated. In turn, a shifting of the zone screws of the inking system, as initiated in this way, can then be detected by the operators of the printing press within a short period of time by a review of the movie of the printed images  04  running in the first section  09  of the display area  08  by the noting of a reversal of the prior tendency toward a color deviation. For video capability, the electronic control of the display area  08 , in particular, should be configured in such a way that video signals can be processed and displayed by it. For this purpose, the control device must be able, for example, to process a sufficiently large signal bandwidth at high speed. 
   The display area  08  has at least one touch-sensitive field for operating and/or for setting the evaluating unit  02  and/or the printing press  06 . In the second section  11 , in particular, the input field  16 ,  17  and/or the operating field  18 ,  19  are embodied as touch-sensitive fields which are usable for setting and/or for operating the evaluating unit  02  and/or for setting and/or for operating the printing press  06 . Thus, the display area  08  is preferably configured as a touch screen. 
   In their preferred embodiments, the display device  01  and/or the evaluating unit  02  have at least two modes of operation. These at least two modes of operation differ in a different design of the display area  08  and/or in the amount, and in particular the number, of the displays which are presented on the display area  08  and/or in the amount of operations and/or the settings of the evaluating unit  02  and/or the printing press  06 . A change from an actually set mode of operation, to a mode of operation of a larger size in regard to the displays and/or to the operations and/or to the settings of the evaluating unit  02  and/or to the printing press  06  preferably is a function of a proof of authorization. This proof of authorization consists, for example, of a password or of an identifying characteristic of the user, of which the system is to be advised by an input for verification. Also, a sequence of the input fields  16 ,  17  and/or of the operating fields  18 ,  19  displayed on the display area  08  can depend on the mode of operation per se. For example, in a defined mode of operation, non-released input fields  16 ,  17  and/or the operating fields  18 ,  19  are not even displayed or are locked out, so that the function otherwise connected with the now locked out or not displayed input fields  16 ,  17  and/or the operating fields  18 ,  19  cannot be performed. For example, the modes of operation may differ in that, in one mode of operation, only functions required for executing a printing order are displayed, while in another mode of operation, for example, all of the settings of the system, up to the settings of the image sensor  03  and those of the printing press  06 , can be changed. 
   The evaluating unit  02  preferably also has a learning mode for use in determining and/or for defining at least one reference image, and a work mode for comparing an actually recorded image with the reference image. The display device  01  indicates, in its first section  09 , a deviation of the actually recorded image from the reference image detected in the test performed by the evaluating unit  02 . The number of printed images  04  to be evaluated in the learning mode can be input at the display area  08  and can be variably adjusted. At the termination of the learning mode, the system can change, preferably automatically, into the work mode. 
   It is of advantage if the system in accordance with the present invention, and in particular the display area  08 , has a function for taking back or for cancelling an accidentally or an erroneously performed input occurring at an input field  16 ,  17  and/or at an operating field  18 ,  19  and/or an erroneous selection from the menu displayed in the fourth section  13  of the display area  08 . Also, data stored in the memory device  26 , which data is no longer needed, can be completely or partially cancelled, such as, for example, by actuating a specific operating field  18 ,  19 . 
   The display area  08  can, for example, indicate, in particular in its fifth section  14 , how many printed images  04  as a whole and/or how many printed images  04 , which are considered to be satisfactory, have already been produced by the printing press  06  in the course of an actual job. A statistical function, which can be called up from the menu that can be displayed in the fourth section  13  of the display area  08 , can display information regarding an individual image and/or several images. This information can be stored in the memory device  26 , preferably limited over time. As the result of a command which can be input into the system, this information can be conducted to a printer, which is not specifically represented, which printer is connected with the evaluating unit  02 , and such information can be printed out there. 
   To perform the above-described functions, and in particular to perform the functions in connection with the display area  08 , the evaluating unit  02  advantageously has an operating system which supports a method for inter-process communication, which is designed for exchanging complex data structures. For example, it is possible to provide Windows NT4.0® (or higher) or Windows 2000® (or higher) as the operating system. Communications can take place in accordance with the COM (Common Object Model)/DCOM (Distributed Component Object Model) standard. 
   While a preferred embodiment of a system for inspecting a printed image, in accordance with the present invention, has been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that changes in, for example, the specific structure of the cylinders in the printing press, the drive for the imprint substrate and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the appended claims.