JP2007137012A - Printer and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To examine whether print image quality is identical among print engines or not conveniently in a printer equipped with a plurality of print engines. <P>SOLUTION: When an inspection mode is started, a sheet fed from a sheet feed unit 100 is delivered, at first, to the print engine 201 of a print unit 200 where an inspection chart is printed. That sheet is further delivered to the print engine 301 of a print unit 300 where an inspection chart is further printed on the same surface. Inspection charts of the print units 200 and 300 are patterned not to overlap. Consequently, such print results as the inspection charts of both print units 200 and 300 are printed on the same surface are obtained in a sheet discharge unit 400. When the print results are visually checked or read out at a reading section 451, a judgment can be made whether color reproducibility coincides between both print engines 201 and 301 or not. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing apparatus that includes a plurality of print engines and that prints one print job by distributing the print jobs to the plurality of print engines.

  As a printing apparatus including a plurality of print engines, there are those shown in Patent Document 1 and Patent Document 2. Further, Patent Document 3 discloses a configuration in which print engines are arranged in a tandem configuration in order to obtain high speed and various paper conveyance properties.

  As described above, in a printing apparatus including a plurality of print engines, one print job is often distributed to the plurality of print engines for printing. When such a printing apparatus is to be applied to a field that requires high print quality, such as commercial printing, it is necessary to match the print image quality of the print engines. In particular, matching of color reproducibility is very important.

  A similar problem occurs in a printing system in which a plurality of individual printers are connected, and is described in Patent Document 4. In the system of this document, each printer is printed with a colorimetric page, each patch of the colorimetric page is measured with a densitometer, and the results of the measurement are combined to calibrate each printer.

  Patent Document 5 discloses a technique for easily grasping the difference between the printed color reproduction and the reference color reproduction in order to match the output color of one print engine with a predetermined reference color. Has been. In this method, a test pattern is printed by a print engine on a reference chart in which a reference color pattern is printed in advance, so that the reference color pattern and the test pattern can be compared on one chart.

U.S. Pat. No. 4,427,285 JP-A-2-215623 JP-A-9-127739 JP 2002-254710 A JP 2000-351261 A

  The method of Patent Document 4 requires manpower to read each colorimetric page printed by a separate printer. Also, if it is attempted to automate, a colorimeter is provided for each printer, which increases costs.

  Moreover, although the method of patent document 5 is related to one print engine, application to a printing apparatus having a plurality of print engines is not conceivable. In other words, if each print engine is supplied to a reference chart and a test pattern is printed, and the characteristics of each print engine are adjusted to the reference based on the printing result, the consistency of image quality between the print engines is improved. Will be able to. However, this method has a problem that the work becomes complicated because it is necessary to prepare a reference chart in advance.

  A printing apparatus according to the present invention includes a plurality of print engines connected to a common paper transport unit extending from a paper feed unit to a paper discharge unit, and distributes and prints pages of an input print job to each print engine. An inspection mode control means for supplying the same paper to each of the print engines in order in the inspection mode, and causing each print engine to print a predetermined inspection chart on the same surface of the paper; Prepare.

  In a preferred aspect of the present invention, the inspection chart to be printed by each print engine is a color gamut inspection chart, and patches of each color to be inspected are arranged so that patches of the same color are adjacent to each other between the print engines. is there.

  In a further preferred aspect, an interval is provided between adjacent patches on the inspection chart, and the printing apparatus includes a stain detection unit that detects print stains from a reading result of at least a part of the intervals. Determination means for determining the reliability of the inspection based on the inspection chart based on the detection result of the dirt detection means.

  In another preferred aspect of the present invention, the inspection chart to be printed by each print engine is a chart for inspecting a printing misalignment between print engines, and includes a mark indicating the same position on the page, and the color of the mark is Different for each print engine.

  According to the present invention, since the inspection charts of a plurality of print engines are printed on the same surface of the same paper, it is easy to compare the print engines, and since they are on the same paper, it is not necessary to consider the difference in the ground color of the paper. Good.

  The best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of an example of a printing apparatus to which the present invention is applied.

  The printing apparatus includes one paper feeding unit 100, two printing units 200 and 300, and one paper discharge unit 400.

  The paper feed unit 100 includes a plurality of paper feed trays (three are illustrated in the figure) 101, 102, and 103. The paper fed from each of the paper feed trays 101 to 103 is supplied to the printing unit 200 connected to the subsequent stage of the paper feed unit 100 through the paper feed conveyance path 105. In this example, an original reading unit 150 for optically reading an original is attached to the upper part of the paper feeding unit 100.

  The two printing units 200 and 300 include electrophotographic print engines 201 and 301 for full-color printing, respectively.

  In this example, the print engines 201 and 301 have a configuration in which four color developing units 203 and 303 of Y (yellow), M (magenta), C (cyan), and K (black) are arranged in tandem (columns). Yes. Each of these four-color developing sections 203 and 303 forms a toner image of each color by electrophotography, and these four-color toner images are transferred onto the intermediate transfer belts 205 and 305, respectively. A full color toner image is formed. The full-color toner images on the intermediate transfer belts 205 and 305 are transferred to the paper by the transfer units 207 and 307. The sheet on which the toner image is transferred is sent to the fixing units 209 and 309, where the toner image is fixed on the sheet. In the case of performing double-sided printing, after fixing the front surface, the fixed paper is once sent to the switchback paths 214 and 314, and then conveyed in the reverse direction to carry the reverse conveying paths 216 and 316. The paper is reversed by introducing the paper to the transfer unit 207, 307 and the back side is printed.

  The two printing units 200 and 300 are connected in tandem. That is, the printing unit 200 receives paper from the paper supply unit 100, and the printing unit 300 receives paper discharged from the printing unit 200. Then, the paper discharged from the printing unit 300 is introduced into the paper discharge unit 400 and discharged to the paper discharge stacker 401 through the paper discharge transport path 405. Hereinafter, for identification, the upstream printing unit 200 in the tandem arrangement as viewed from the paper feeding unit side is referred to as A unit, and the downstream printing unit 300 is referred to as B unit.

  The configuration of both the A and B units (200 and 300) will be described in detail as follows.

  That is, the A unit accepts a sheet supplied from the sheet feeding conveyance path 105 of the sheet feeding unit 100, and when printing on the sheet by the A unit, the sheet 210 conveys the sheet conveyance path by the print engine 201. To the transport path 212 toward As a result, the sheet is introduced into the print engine 201, the toner image is transferred by the transfer unit 207, and the toner image is fixed by the fixing unit 209. When performing double-sided printing on the paper, the paper for double-sided printing is transported as described above, and the back side is printed. In this way, the paper on which printing has been completed is sent to the B unit through the paper discharge transport path 217. The above is the case where the A unit performs printing on the paper supplied from the paper feeding unit 100. However, when printing is not performed on the paper using the A unit, the paper passes by switching the gate 210. Is sent to the transport path 215, and further to the B unit through the transport path 217 for paper discharge.

  Although the operation of the A unit has been described above, the operation of the B unit is the same. That is, when printing is performed on the paper supplied from the A unit by the B unit, the paper is sent to the transport path 312 toward the print engine 301 by switching the gate 310, and after the image is printed, the paper discharge unit. It is discharged to 400. Further, when printing is not performed in the B unit, the sheet is similarly discharged by the switching of the gate 310 to the paper discharge unit 400 through the passing conveyance path 315.

  Depending on the configuration of the printing apparatus, a post-processing unit that performs post-processing such as stapling and punching may be provided. In such a case, the post-processing unit can be provided at the rear stage of the paper discharge unit 400. .

  The A unit control unit 220 and the B unit control unit 320 are responsible for the control of paper conveyance and printing in both the A and B units as described above. These control units 220 and 320, and control units (not shown) of the paper feed unit 100 and paper discharge unit 400, respectively, according to instructions from a system control unit 500 (see FIG. 2) that controls the entire printing apparatus. By controlling each of the components, integrated operation control is realized as a whole printing apparatus.

  The printing apparatus described above can be regarded as a configuration in which the print engines 201 and 301 are connected to a series of paper conveyance paths including the conveyance paths 105, 215, 315, and 405, that is, the conveyance paths 105 and 215. , 315, and 405 are a common sheet conveyance path for the two print engines 201 and 301.

  The printing apparatus of FIG. 1 has two printing units 200 (A unit) and 300 (B unit), so that a high-speed printing operation is possible.

  That is, in this printing apparatus, printing is performed by alternately supplying sheets supplied from the sheet feeding unit 100 to the A unit and the B unit for each sheet. That is, the individual sheets are printed only in one of the units A and B, and the other unit passes through the passing conveyance path 215 or 315 (that is, passes through that unit without printing). In the sheet conveyance paths 105 and 405 common to both units (all sheets pass through this path), the sheet conveyance paths 212, 214, 216, 312, 314, and 316 in the individual print engines 201 and 301 are doubled. Convey paper at a speed of. As a result, the entire printing apparatus can perform printing at twice the printing speed of the individual print engines 201 and 301. Similarly, the paper may be transported at the double speed (or higher speed) in the passing transport paths 215 and 315.

  In such a printing apparatus, each page of one print job is printed by being divided into the A unit and the B unit. Therefore, it is necessary to maintain the same print image quality between the two units. Therefore, in this embodiment, a special mode (called an inspection mode) for inspecting the print image quality of both the A and B units is introduced into the printing apparatus.

  In this inspection mode, the paper fed from one of the paper feed trays of the paper feeding unit 100 is first supplied to the print engine 201 of the A unit by switching the gate 210 to print a predetermined inspection chart. This sheet is further supplied to the print engine 301 of the B unit by switching the gate 310 to print a predetermined inspection chart. In this series of processing, the respective inspection charts are printed on the same surface of the same sheet in the A unit and the B unit.

  The inspection charts printed by the A and B units are the primary colors of YMCK, the secondary colors (R, G, B, etc.) that are two of the YMC colors, the tertiary colors and the higher colors. Each color patch (small area filled with a single color) selected in advance from the next color or the like is arranged. It is common to use a plurality of patches having different densities for each color. The inspection chart for the A unit and the inspection chart for the B unit are designed so that the patches do not overlap each other.

  An example of the patch arrangement on the inspection chart 600 output from the B unit in the inspection mode (that is, finally output as the inspection chart of the entire printing apparatus) is shown in FIG. In this figure, each rectangular area 610 represents a patch. Of the signs “An” and “Bn” (n is an integer from 01 to 48) shown in each patch, “A” and “B” are patches for the A unit and B unit, respectively. Show. The subsequent integer n is a serial number assigned to each color and density combination to be inspected. Therefore, patches having the same serial number n, such as “An” and “Bn”, are patches of the same color and density. That is, “An” and “Bn” are obtained by printing patches of the same color and density in the A unit and the B unit, respectively.

  As shown in FIG. 2, in this embodiment, the patches printed by the A unit and the patches printed by the B unit are arranged so that the same color and density (that is, the same serial number) are adjacent to each other. Has been. This makes it easy to check whether patches of the same color and density are output in the same color and density by both units by visual confirmation by a human. In many cases, the conventional inspection chart employs a regular patch arrangement in which patches of the same color are arranged in a line in the order of density, but in the example of FIG. 2, the same color patches are dispersedly arranged on the paper surface as much as possible. is doing. This reduces in-plane non-uniformity (print density unevenness, etc.) in printing with the print engine 201 or 301 and in-plane non-uniformity in reading with the reading unit 451 or the document reading unit 150. Yes.

  A control mechanism of the printing apparatus for printing such an inspection chart is shown in FIG. In FIG. 3, a system control unit 500 sends commands to the control units of the units 100 to 400 of the printing apparatus to control the operation of the entire printing apparatus. Although not shown in FIG. 1, the system control unit 500 may exist separately from the units 100 to 400, and any one of the control units of the units 100 to 400 serves as the system control unit 500. May function.

  The storage device 550 is a non-volatile storage device such as a hard disk or an EEPROM, for example, and stores data for the inspection chart 600A for the A unit and data for the inspection chart 600B for the B unit. In the figure, the patch arrangement pattern of the inspection chart 600A for the A unit is illustrated as a representative of both. As shown in the figure, on the inspection chart 600A, patches 610A for the A unit (indicated by a solid rectangle with a symbol “An” in the drawing) are arranged in a predetermined order. Between the adjacent patches 610A, there is a sufficient interval to print a patch of B unit (indicated by a broken-line rectangle in the figure), whereby the A and B units print. I try not to overlap each other. In addition, a gap 620 is also provided between the patches 610A adjacent to each other in the vertical direction printed by the A unit so that the adjacent patches do not overlap each other. Similar spacing 630 is also provided between adjacent patches in the lateral direction. In the inspection chart 600B for the B unit, patches are arranged in the blank area indicated by the broken line in the illustrated inspection chart 600A, and the portion of the patch 610A indicated by the solid line is blank.

  When entering the inspection mode, the system control unit 500 reads the data of the inspection charts 600A and 600B from the storage device 550, and supplies the data to the A unit control unit 220 and the B unit control unit 320 for printing. .

  FIG. 4 is a flowchart showing a processing procedure of the system control unit 500 in the inspection mode. The processing in the inspection mode is executed as part of the startup processing when the printing apparatus is turned on, for example. Further, in order to detect a change in image quality characteristics of the print engines 201 and 301 after printing in large quantities, the inspection mode process can be performed every time a predetermined number of sheets are printed. Of course, not only such automatic execution but also the operator can explicitly instruct the system control unit 500 to execute the inspection mode.

  When the inspection mode processing is started in this manner, the system control unit 500 sends an instruction to the paper feeding unit 100 to feed one sheet from a predetermined paper feeding tray (S10). Then, an instruction is sent to the A unit controller 220, and the gate 210 is controlled to convey the paper to the print engine 201 (S12). Then, the A unit inspection chart 600A is supplied to the A unit controller 220 (S14), and this is printed on the surface of the paper (S16). Then, the system control unit 500 controls the gate 310 of the B unit to convey the sheet on which the inspection chart 600A is printed to the print engine 301 (S18), and the inspection chart 600B for the B unit is transferred to the B unit. This is supplied to the controller 320 (S20), and this is printed on the surface of the paper (S22).

  By such processing, as shown in FIG. 2, an inspection chart 600 is created in which the patch groups printed by both the A and B units are shown on the same surface of one sheet. It is also possible for the operator to visually check the inspection chart 600 to determine whether the print image quality of both the A and B units is the same. In this inspection chart 600, patches of both A and B units are printed on the same surface of the same sheet, and patches of the same color and density are arranged adjacent to each other. It is easy for the operator to determine whether or not they match.

  Further, instead of visually judging the inspection chart 600 output in this way, or in addition to such inspection by a human, each patch of the inspection chart is read by the reading unit 451 (see FIGS. 1 and 3). It can also be inspected. In this case, the reading unit 451 is provided on the upstream side of the paper discharge tray 401 (and the branch point to the subsequent unit) on the paper discharge transport path 405 of the paper discharge unit 400. The reading unit 451 may be a colorimeter or a color image reading device such as a line sensor or a two-dimensional area sensor. The processing procedure of FIG. 4 shows the flow of automatic inspection using such a reading unit 451 after S22. That is, when performing automatic inspection using the reading unit 451, after printing the inspection chart in the B unit (S22), the system control unit 500 causes the sheet on which the inspection chart has been printed to pass below the reading unit 451. At that time, the reading unit 451 reads the chart (S24). When a colorimeter is used as the reading unit 451, the reading unit 451 outputs color measurement data of each patch 610, and when a color image reading device such as a line sensor is used, the reading unit 451 outputs color image data. It will be. In either case, the output of the reading unit 451 is passed to the system control unit 500. The system control unit 500 receives the output of the reading unit 451, processes it (S26), and outputs the processing result in the form of screen display or print output (S28). The process of S26 creates, for example, a table in which the colorimetric data values of each patch are arranged and arranged for each of the A and B units, and various graphs showing the print image quality of each unit. It is processing. When the reading unit 451 is a color image reading device such as a line sensor, in order to obtain such color measurement data, each patch is identified from the read image, and the color measurement data value of each patch is calculated. Pre-processing is required. The process of S26 described above is conventionally known. The operator determines whether the difference in color reproducibility between the printing units 200 and 300 is within an allowable range by referring to the processing result data. If the difference is unacceptable, the image quality parameters of either or both printing units are adjusted to match the color reproducibility of both.

  Further, in S26, a color mismatch between the A and B units is further detected, and when there is a mismatch exceeding the allowable range, the image quality parameter is automatically corrected so as to correct it in S28. Good.

  Instead of automatically reading the inspection chart 600 by the reading unit 451 provided on the paper discharge conveyance path 405, the operator sets the inspection chart 600 output to the paper discharge tray 401 on the original reading unit 150 and reads it. Semi-automatic processing is also possible.

  The preferred embodiments of the present invention have been described above. As described above, in the normal mode in which the document is printed, one sheet is not printed through the print engines 201 and 301 of both units. In the present embodiment, the one sheet is not printed. A new inspection mode that passes through both engines 201 and 301 and prints on the same side of the paper is provided. Thereby, the inspection charts of the two print engines 201 and 301 can be printed on the same side of the same sheet. As in the prior art (Patent Documents 4 and 5), when the inspection chart of each printer is printed on separate paper, if the ground color of the paper is different for each printer, the colors match or do not match each other. Judgment becomes very difficult. However, it is not always easy to supply the same type of paper to each print engine at the time of inspection. This is because a plurality of types of paper may be mixed on the same paper feed tray. On the other hand, in this embodiment, since patches of a plurality of print engines are printed on the same surface of the same sheet, such a complicated problem does not occur. Also, if different inspection papers are printed by supplying different papers with the same ground color to the print engines 201 and 301, the difference in paper ground color does not matter, but each chart is read by the reading unit 451. In addition, there may be a case where a change in reading characteristics with time during reading by the document reading unit 150 becomes a problem. In particular, when the document reading unit 150 is manually read, the time difference when both charts are read tends to be large, so that the possibility that the difference adversely affects the inspection result is increased. However, such a problem does not occur if the inspection chart of each printing unit is printed on the same surface of the same sheet as in this embodiment.

  When each print engine prints the inspection chart in order on the same surface of the paper as in the present embodiment, the “fogging” (in the portion that should be blank) is printed when printing with any of the print engines. (Phenomenon in which density increases due to toner adhering during development) When other stains occur, color reproduction of inspection charts printed by other print engines is also affected. If this is left unattended, incorrect colorimetric data is obtained, and incorrect color reproducibility adjustment may be performed based on the incorrect data. Therefore, as a modified example for eliminating such a situation, the reading unit 451 and the document reading unit 150 read not only patches but also intervals 620 and 630 (see FIG. 3) between the patches, and the like, such as fogging. It can also be configured to automatically determine whether or not dirt is generated. In this determination, for example, the entire region of the intervals 620 and 630 or some representative portions of them are read. Then, if the read colorimetric data values of the respective parts substantially coincide with each other, fog or the like does not occur. Otherwise, it may be determined that fog or the like has occurred. When it is determined that fog or the like has occurred, the system control unit 500 puts the printing apparatus into a print-prohibited state, and displays a message indicating that the fog or the like has occurred on the display device attached to the printing apparatus or a remote monitoring computer. indicate. In addition, since the inspection result of the inspection chart at this time has low reliability as described above, it is discarded, or information indicating that the reliability is low is added or presented to the user or stored. In addition, it is also suitable to perform control such as inspecting for dirt such as fog prior to calculation for inspection of each patch on the inspection chart (calculation of colorimetric value, etc.), and canceling calculation for inspection of the patch when contamination is detected. It is. By such processing, the operator can recognize that a serious failure such as fog has occurred, can take necessary measures, and is not confused by the unreliable inspection result. .

  In the above example, a printing apparatus including two printing units 200 and 300 is taken as an example. However, a similar inspection mode process can be performed in a printing apparatus having three or more printing units. However, when the number of printing units increases, the inspection charts of all units may not be printed on the same paper surface due to the limitation of the area of the paper surface. In such a case, for example, an inspection chart for some units may be printed, such as printing an inspection chart for the A unit and the B unit on one sheet and printing an inspection chart for the A unit and the C unit on another sheet. It is only necessary to print on a plurality of sheets by overlapping. Thereby, the consistency of color reproduction between the printing units can be inspected in a chained manner using the overlapping inspection charts as a medium. In this case, in the inspection mode process, a plurality of sheets are fed, but each sheet is printed by the print engine of the corresponding printing unit, and the other printing units are simply controlled to pass. The

  Also, depending on the system configuration of the printing apparatus, different types of print engines may be provided, such as two full-color print engines and two monochrome print engines. In such a case, in the inspection mode, the same paper is printed by the same type of print engine, and the other types of print engines are simply controlled to pass.

  In the above description, the case of detecting a difference in color reproducibility between print engines has been described as an example. However, the same processing can be applied to detection of a positional deviation of a print image between print engines.

  In this case, in the inspection mode, for example, an inspection chart for positional deviation inspection is printed on each of the A unit and the B unit. This inspection chart includes a mark for indicating a predetermined position on the page. That is, the marks printed by the printing units (A, B) indicate the same position when there is no positional deviation between them. In order to be able to identify which printing unit the printed mark belongs to, the color of the mark is different for each printing unit.

  FIG. 5A shows an example of such a misalignment inspection mark (chart). In this example, the A unit chart 702A to be printed on the A unit is formed by combining four L-shapes with different orientations to form a white cross, and the B unit chart 702B to be printed on the B unit is It is a cross-shaped figure. When the A unit chart 702A and the B unit chart 702B are not misaligned in printing between the A unit and the B unit, as shown in the printing result 704, the white chart of the A unit chart 702A Positioning is performed so that the cross of the B unit chart 702B is printed at the center of the extracted cross. That is, the intersection of the white cross of the A unit chart 702A and the cross of the B unit chart 702B are set at the same position. When a printing misalignment occurs between the A unit and the B unit, the positional relationship between the white cross shown by the A unit chart 702A and the cross of the B unit chart 702B is visually observed. Etc. can be easily confirmed. In order to easily distinguish the two, it is preferable that the A unit chart 702A and the B unit chart 702B have different colors.

  FIG. 5B shows another example of a misalignment inspection mark. In this example, the marks for inspecting the lateral deviation, that is, the A unit chart 706A and the B unit chart 706B are composed of line segments (two line segments in the illustrated example) extending in the vertical direction of the paper. When there is no printing misalignment between the A unit and the B unit, the lower end of the line segment of the A unit chart 706A and the upper end of the line segment of the B unit chart 706B are located at the same position. Is positioned. Therefore, when there is no lateral displacement between the two units, the line segment of the A unit chart 706A and the line segment of the B unit chart 706B are on a straight line. On the contrary, if there is a lateral displacement, the charts 706A and 706B will not be in a straight line, and this can be detected visually or automatically. In order to easily distinguish the two, it is preferable that the A unit chart 706A and the B unit chart 706B have different colors. As the mark color, it is preferable to use one of the primary colors of printing, that is, CMYK. This is because the inspection mark is printed only on the single photosensitive drum in the printing unit, and the influence of the positional deviation between the photosensitive drums in the single printing unit does not appear. is there. The positional deviation between the photosensitive drums in a single printing unit may be detected using a separate chart.

  Further, if the A unit chart 708A and the B unit chart 708B for vertical deviation inspection are used, the vertical printing deviation can be detected based on the same concept.

  FIG. 5C shows still another example of the misalignment inspection chart. This example is an inspection chart disclosed in Japanese Patent Laid-Open No. 2001-109218 by the present applicant.

  The illustrated chart is for detecting a positional deviation in the vertical direction. In the B unit chart 710B, line segments 711B extending in the horizontal direction are arranged in a matrix, and the line segments 711B in the same row ride on the same straight line. In the figure, an example of 5 rows and 5 columns is shown, but this is only an example. On the other hand, the A unit chart 710A is obtained by gradually shifting the vertical position of each line segment 711B in the same row in the B unit chart 710B. When there is no printing misalignment between the A unit and the B unit, as shown in the printing result 712, each line segment 711A in the center column in the matrix of the A unit chart 710A and the B unit chart 710B The positional relationship between the two charts is determined so that each line segment 711B of the center column in the matrix overlaps. On the other hand, when a vertical displacement occurs between the A unit and the B unit, the line segments 711A and 711B in other columns than the center column overlap. Then, the positional deviation amount in the vertical direction can be obtained depending on which line segment overlaps. Note that it is preferable for identification that the line segment 711A and the line segment 711B are different colors, in particular, one is a chromatic color and the other is black. As the colors of the line segments 711A and 711B, it is preferable to use the primary color of printing, that is, one of CMY on one side and K on the other side.

  The lateral displacement can be detected by using a chart obtained by rotating each chart 710A, 710B shown in FIG. 5C by 90 degrees.

  The chart shown in Japanese Patent Application Laid-Open No. 2001-109218 is for inspecting the positional deviation of the photosensitive drums of the respective colors included in a single print engine. It is used to detect misalignment between engines. The positional deviation between the colors in the single print engine may be detected by separately printing the same chart on the photosensitive drum of each color.

  In the above description, the electrophotographic printing apparatus has been described as an example. However, the control in the inspection mode of the present embodiment does not depend on the electrophotographic system. Is also applicable.

It is a figure which shows an example of the printing apparatus with which this invention is applied. It is a figure which illustrates the patch arrangement | sequence of the inspection chart for color reproduction inspection produced in embodiment. It is a figure for demonstrating the control mechanism for the process at the time of test | inspection mode. It is a figure which shows the process sequence of the system control part at the time of test | inspection mode. It is a figure which shows an example of the test | inspection chart for position shift inspection. It is a figure which shows another example of the inspection chart for position shift inspection. It is a figure which shows another example of the test | inspection chart for position shift inspection.

Explanation of symbols

  100 paper feed unit, 200, 300 printing unit, 201, 301 print engine, 400 paper discharge unit.

Claims (7)

A printing apparatus that includes a plurality of print engines connected to a common paper transport unit extending from a paper feed unit to a paper discharge unit, and distributes and prints pages of an input print job to each print engine,
Inspection mode control means for sequentially supplying the same paper to each of the print engines in the inspection mode and causing each print engine to print a predetermined inspection chart on the same surface of the paper;
A printing apparatus comprising:   A reading device is provided in front of the paper discharge unit on the paper transport unit, and in the inspection mode, further includes a reading device that generates a read image by reading a print surface of a sheet on which an inspection chart is printed by each print engine. The printing apparatus according to claim 1, wherein the state of the printing apparatus is determined based on the determination.   The printing apparatus according to claim 1, wherein the inspection mode control unit causes each print engine to print an inspection chart in a non-overlapping area assigned to each print engine on a sheet of paper.   The inspection chart to be printed by each print engine is a chart for color gamut inspection, and patches of each color to be inspected are arranged so that patches of the same color are adjacent to each other between the print engines. The printing apparatus according to 1 or 2. An interval is provided between adjacent patches on the inspection chart,
The printing apparatus includes:
A stain detection means for detecting print stains from at least a part of the reading results of the intervals;
Determination means for determining the reliability of the inspection based on the inspection chart based on the detection result of the dirt detection means;
A printing apparatus according to claim 4.   The inspection chart to be printed by each print engine is a chart for inspecting the printing position between the print engines, and includes a mark indicating the same position on the page, and the color of the mark is different for each print engine. The printing apparatus according to claim 1. A control method for a printing apparatus that includes a plurality of print engines connected to a common paper transport unit extending from a paper feed unit to a paper discharge unit, and distributes and prints pages of an input print job to each print engine. ,
In the inspection mode, the same paper is supplied to each print engine in turn,
Have each print engine print a predetermined inspection chart on the same side of the paper,
A control method for a printing apparatus.

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