JP2021088107A - Printer - Google Patents

Abstract

To provide a printer that can prevent a density value measured after trial printing is transferred to main printing from coming out of an allowable range, while suppressing wasted paper from increasing during the trial-printing.SOLUTION: The printer comprises: density value measuring means 14 that measures a density value of a trial-printed matter being conveyed; acceptance/rejection determining means 16 that determines whether the trial-printed matter is acceptable or rejectable based on the density value measured by the density value measuring means 14; and main-printing transferring means 17 that determines whether transfer of trial-printing to main-printing is acceptable or not on the basis of a determined result of acceptance and rejection by the acceptance/rejection determining means 16. The main-printing transferring means 17 is configured to be able to select plural repeating times of the determination of acceptance by the acceptance/rejection determining means 16 as a condition for determining that the transfer to the main-printing is acceptable.SELECTED DRAWING: Figure 2

Description

The present invention relates to a printing machine that performs a test print before the main print.

In such a printing machine, a predetermined number of sheets are printed as a test print and the density is confirmed (density matching) before the main printing is performed. Specifically, a predetermined number of sheets are printed as a test print, the density of the test-printed printed matter is measured, and it is determined whether or not the measured density value is within an allowable range with respect to the target density value. If it is determined that the ink is within the allowable range, the printing shifts to the main printing without stopping the printing, and if it is determined that the printing is out of the allowable range, the ink supply amount is adjusted so that the measured density value is within the allowable range. (For example, Patent Document 1), the density is confirmed (density adjustment) by further performing a test print while correcting the above. The printed matter of the test print is a waste paper.

As described above, when the measured density value is within the permissible range, the printing is immediately started. Even after shifting to the main printing, the density status of the printed matter is monitored and feedback is provided as necessary, but the measured density value may be out of the allowable range. Printed matter during main printing whose density value is out of the permissible range becomes waste paper.

Japanese Unexamined Patent Publication No. 2013-75518

One of the reasons why the measured density value is out of the permissible range is the density measurement of the printed matter (including the printed matter in the process of hunting (overshooting or undershooting) the density) before the density converges (stable). This is because the transition to the main printing is judged based on the result of the printing. This is also likely to occur when the number of test prints is relatively small. Therefore, this problem can be solved by measuring the density of the printed matter after the density has converged (stable density), but the density has converged (stable) depending on the area ratio of the pattern and the amount of ink supplied. By the time, a large number of test-printed sheets are required, and all of the test-printed printed matter is treated as waste paper, so that a large amount of waste paper is generated, and early improvement is required.

The present invention has been made to solve such a problem, and provides a printing machine that suppresses an increase in waste paper during test printing and prevents the density value measured after the transition to main printing from becoming out of the permissible range. To provide.

In order to achieve the above object, the printing machine according to the present invention has a density value measuring means for measuring the density value of the test printed matter during transportation and a test printed matter based on the density value measured by the density value measuring means. Is provided with a pass / fail determination means for determining whether or not the print is passed or a pass / fail determination, and a main print transition means for determining whether or not the transition from the test print to the main print is possible based on the pass / fail determination by the pass / fail determination means. The means is characterized in that it is configured as a condition for determining that the transition to the main printing is possible by a plurality of consecutive pass determinations by the pass / fail determination means.

According to the above configuration, when the pass determination by the pass / fail determination means is repeated a plurality of times, it can be determined that there is a high possibility that the concentration has converged (stable) to the extent that there is no problem. Therefore, if the pass judgment is shifted to the main printing on the condition that the pass judgment is repeated multiple times, the density value measured after the main printing shift is out of the permissible range while suppressing the required minimum waste paper at the time of the trial printing. Can be prevented.

Further, in the printing machine according to the present invention, the density value measuring means measures the density value of each of the plurality of solid patches printed in the range corresponding to each ink pot key of the test printed matter, and the density value of the plurality of solid patches is measured. Among them, a concentration-related index deriving means for deriving the number of solid patches whose measured concentration value is within the target concentration value as a concentration-related index is provided, and the pass / fail determination means is derived by the concentration-related index deriving means. When the density-related index is equal to or greater than the target number, which is the target index, it is determined that the test-printed matter has passed, and the density-related index derived by the density-related index deriving means is less than the target number. In addition, it may be a means for determining that the test print is unacceptable.

As described above, when the number of solid patches derived by the density-related index derivation means is equal to or greater than the target number, the pass / fail determination means determines that the test-printed printed matter is acceptable, and the density-related index derivation means is used. If the number of derived solid patches is less than the target number, it is determined that the test-printed printed matter has failed.

Further, in the printing machine according to the present invention, the density value measuring means measures the density value of each of the plurality of solid patches printed in the range corresponding to each ink pot key of the test print printed matter, and the plurality of the measured density values are measured. It is provided with a concentration-related index derivation means for deriving the average concentration value obtained by dividing the total concentration value of the solid patch concentration values by the number of solid patches as a concentration-related index, and the pass / fail determination means is the concentration-related index derivation means. When the difference between the derived average density value and the target density value, which is the target index, is within the set range, it is determined that the test print is acceptable, and the average density value derived by the density-related index derivation means is determined. When the difference between the density value and the target density value is out of the set range, it may be a means for determining that the test-printed printed matter has failed. In the derivation of the average density value, if there is a range corresponding to the ink pot key for which there is no image other than the solid patch, the solid patch in that range can be excluded from the derivation target of the average density value.

As described above, the pass / fail determination means determines that the test-printed printed matter is acceptable when the difference between the average density value derived by the density-related index deriving means and the target density value is within the set range. If the difference between the average density value derived by the density-related index derivation means and the target density value is out of the set range, it is determined that the test-printed printed matter has failed.

According to the present invention, by providing the main printing transition means for shifting to the main printing when the acceptance determination is made a plurality of times in succession, the density value measured after the transition to the main printing is suppressed while suppressing the increase in the waste paper at the time of the test printing. Can be provided to prevent the printing machine from being out of the permissible range.

It is a side view of a printing machine. It is a block diagram which shows the control structure of a printing machine. It is a flowchart for performing the test printing OK determination process of a printing machine, and shows the first process. It is a flowchart for performing the test printing OK determination processing of a printing machine, and the continuation processing is shown from FIG. It is a flowchart for performing the test printing OK determination process of a printing machine, and the process which continues from FIG. 4 is shown.

Hereinafter, a printing machine according to an embodiment of the present invention will be described with reference to the drawings.

The printing machine 1 has a paper stacking table 2, a paper feeding unit 4 for feeding out printing paper one by one from the paper stacking table 2 by the feeder device 3, and five colors (5 colors) on the printing paper sent out from the paper feeding unit 4. A range corresponding to the printing unit 5 for printing (a color including at least one special color) and each ink pot key (sometimes simply referred to as a key) of the printing paper (printed matter) printed by the printing unit 5. It is provided with an RGB camera 6 which is an RGB type imaging means for capturing a plurality of solid patches (not shown) printed on the paper, and a paper ejection unit 7 for transporting and ejecting the printing paper after imaging. There is. In FIG. 1, the paper stacking table 2 side is the front side, the paper ejection portion 7 side is the rear side, and the direction of penetrating the paper surface is the left-right direction (or width direction), which will be described below.

The printing unit 5 has four printing units 5A, 5B, 5C, 5D for printing the four process colors C (cyan), M (magenta) Y (yellow), and K (black), and other than the four process colors. It is equipped with a printing unit 5E for printing a special color which is a color. In this embodiment, the printing unit 5E for printing the spot color is arranged at the rear end, but it may be arranged at any position. The printing unit 5A corresponds to the unit 1 appearing in the flowchart described later, the printing unit 5B corresponds to the unit 2 appearing in the flowchart described later, and the printing unit 5C corresponds to the unit 3 appearing in the flowchart described later. The print unit 5D corresponds to the unit 4 appearing in the flowchart described later, and the print unit 5E corresponds to the unit n appearing in the flowchart described later.

The RGB camera 6 is housed in a box 9 arranged at the upper part on the front end side of the paper ejection unit 7, and is arranged in step 10 between the printing unit 5E located at the rearmost portion and the paper ejection unit 7. Multiple solid patches of printing paper conveyed through the formed openings (not shown) are imaged. The opening can be switched between an open state and a closed state by a lid (not shown) that can be opened and closed. Further, when it is desired to cross step 10 for the purpose of inspection or trouble solving on each of the pair of side wall portions 11 and 11 (only one side is shown in FIG. 1) provided in the left-right direction of the paper ejection portion 7, an RGB camera is used. A push button 12 for suspending and resuming the imaging by 6 is provided. By pressing the push button 12, the imaging by the RGB camera 6 is interrupted, and by pressing the push button 12 again, the imaging by the RGB camera 6 is restarted. The push button 12 can also be provided on the rear wall portion of the paper ejection portion 7. Further, when the vehicle is interrupted, the push button 12 blinks to notify the operator of the interruption. Examples of the RGB camera 6 as the imaging means include a line sensor camera, a CMOS camera, and a CCD camera. The imaging data of each solid patch imaged by the RGB camera 6 is input to the density value calculation means 13 provided in the control unit S shown in FIG. 2, and the density value calculation means 13 calculates the density value of each solid patch. The RGB camera 6 and the density value calculating means 13 constitute a density value measuring means 14 (see FIG. 2) for measuring the density values of a plurality of solid patches. When the printing machine 1 is configured as a reversing machine having a reversing device between the printing units, the RGB camera 6 is also provided at the arrangement position of the reversing device so that the preprinted surface (the surface to be printed before the reversing) is provided. ) Can be configured to capture multiple solid patches.

FIG. 2 shows a block diagram for performing a test print OK determination process of the printing machine of the present invention. That is, the printing machine includes a control unit S into which the imaging data from the RGB camera 6 is input, and the control unit S is associated with the density value calculating means 13 for calculating the imaging data from the RGB camera 6 as a density value. The index derivation means 15, the pass / fail determination means 16, and the final printing transfer means 17 are provided.

As described above, the density value calculation means 13 is a means for calculating the density value of each solid patch based on the imaging data of each solid patch imaged by the RGB camera 6. In addition, you may use the density value which converted the calculated solid density value of RGB into the solid density value of CMYK.

The concentration-related index derivation means 15 is a means for deriving the number of solid patches within the target concentration value among the concentration values of the plurality of solid patches as the concentration-related index. For example, if the target concentration value is set to a concentration value having a predetermined range set in advance and the concentration value is set to, for example, 1.4 to 1.6, the measured concentration value is the target concentration value 1.4 to 1. The number of solid patches contained in 1.6 will be derived. The setting of the target density value can be freely changed, for example, it can be changed for each color or according to the work target to be printed.

The pass / fail determination means 16 is a means for determining whether or not the printed matter that has been test-printed passes or fails based on the density-related index derived by the density-related index deriving means 15 and the target index. Specifically, when the number of solid patches derived by the density-related index deriving means 15 is equal to or greater than the target number, which is the target index, it is determined that the test-printed printed matter is acceptable, and the density-related index is determined. When the number of solid patches derived by the extraction means 15 is less than the target number, it is determined that the test-printed printed matter has failed. For example, when the total number of solid patches is 21 (when there are 21 ink pot keys), the total number of 21 may be the target number, or any number of 20 or less may be set. The number of targets can be changed for each color and the work target to be printed. In addition, if there is a range corresponding to the ink pot key that has no image other than the solid patch, the number of solid patches in that range may not be added to the total number of solid patches or the number of solid patches included in the target density value. When not added in this way, the number of targets, which is an index of the target for which the pass / fail determination means 16 determines the pass / fail, is a number calculated from the set pass ratio (corresponding to the final printing transition OK% described later). ..

The main printing transition means 17 can select one or a plurality of consecutive pass determinations by the pass / fail determination means 16 as a condition for shifting from the trial printing to the main printing. Further, the number of times of the plurality of times can be set to any number of 2 or more.

When the pass determination by the pass / fail determination means 16 is repeated a plurality of times (twice or more), it can be determined that there is a high possibility that the concentration has converged (stable) to the extent that there is no problem. Therefore, if the pass judgment is made multiple times (twice or more) in succession, and the final printing is performed, the density value measured after the main printing is reduced while suppressing the minimum required paper loss during the trial printing. It is possible to prevent the product from being out of the permissible range.

Further, the main printing transition means 17 can select one pass determination by the pass / fail determination means as a condition for shifting from the trial printing to the main printing.

As described above, since the main print transfer means 17 is configured to be able to select and set the conditions for shifting from various test prints to the main print, suitable conditions can be accurately set according to the required quality level of the printed matter to be printed. it can. That is, in the case of a printed matter having a high required quality level regarding density, a plurality of (two or more) consecutive pass judgments are selected as the above condition, and in the case of a printed matter having a low required quality level regarding density, the condition is passed. By selecting one determination, the waste paper can be further reduced and printing can be performed efficiently. The condition may be manually operated by the operator to be set to an arbitrary value, or may be automatically selected and set by the control unit S from the job (JOB) information.

Next, a test print OK determination process, which is a process of shifting from the test print to the main print, will be described based on the flowcharts shown in FIGS. 3 to 5. 3 to 5 are a series of flowcharts for performing the test printing OK determination process, but since they cannot be described in one figure, they are divided into three sheets.

First, make various settings. Specifically, the target density, the main print transition OK%, and the main print transition determination number are set (step S1). The target density is the density value of the solid patch of each target color, and the upper limit value and the lower limit value of the permissible range are set, or the permissible deviation amount with respect to the target value and the target value is set. The main printing transition OK% is the ratio (%) of the number of solid patches in the target density that can be judged to be able to be transferred to the main printing, and is set for each unit (for each color). This final printing transition OK% is a condition for the pass / fail determination means 16 to determine pass / fail. The number of determinations for main printing transition is a condition for determining that the transition from trial printing to main printing is possible, and the number of trial printings determined to be OK% or more for main printing transition is set for each unit (for each color). This number of times is configured to select any of 1 time, 2 times in a row, and 3 times in a row. The number of times of the main printing transition determination is a condition for the main printing transition means 17 to determine that the trial printing can be shifted to the main printing.

Next, the number of test print density determination sheets is set (step S2). The number of test print density determinations is the number of prints per test print. In this embodiment, the default value is 30 sheets. The number of test print density determinations can be set for each number of test prints. For example, the number of prints of the third test print can be set smaller than the number of prints of the second test print. The density value of the solid patch at each position in the test-printed printed matter is the remaining density value of the last 10 sheets of the test-printed printed matter for which the test-print density is determined, excluding the minimum value and the maximum value. It is the average value of eight concentration values. However, the density value of the solid patch at each position in the test printed matter is not limited to this. For example, it can be the average value of the remaining three density values excluding the two minimum and maximum values from the last five density values. Alternatively, it may be the density value of the last one printed matter in the test printed matter of the number of test print density determination sheets. It is also possible to use the average value of the density values of the last three printed matter in the test printed matter of the number of test print density determination sheets. When the above settings are completed, the mth test printing (for example, the first time) is started (step S3).

It is determined whether or not the number of prints of the m-th (first) trial print has reached the set number of trial print density determinations (trial print m density determination number) of the set m-th trial print (step S4). When it is determined that the number of prints has reached the set mth (first) density determination number, the number of keys in which the density value measured for the color printed by the unit 1 is within the target density is calculated (unit 1). Calculate the number of OK keys for the m-th (first) trial printing) (step S5). The number of keys is synonymous with the number of solid patches. Next, whether or not the calculated value of (the number of keys of unit 1 that has entered the target density) ÷ (the number of all keys of unit 1) × 100% is equal to or greater than the set value of the set final printing transition OK%. Determine (step S6). If the calculated value is equal to or greater than the set value of the final printing transition OK%, a pass judgment is made. It is determined whether or not the number of pass determinations has reached the set number of final printing transition determinations (one, two consecutive times, or three consecutive times) (step S7). If it is determined that the result has been reached, the main printing transition OK flag of the unit 1 is set (step S8), and the determination of the unit 2 is performed (step S9). If it is determined that the value has not been reached, the process proceeds to the determination of unit 2 (step S9). Further, if it is determined in step S6 that the value is less than the set value of the final printing transition OK%, the determination is performed on the unit 2 (step S9).

When the process proceeds to step S9, the number of keys in which the density value measured for the color printed by the unit 2 enters the target density is calculated (the number of OK keys for the mth (first) test printing of the unit 2 is calculated. ). Next, whether or not the calculated value of (the number of keys of the unit 2 that has entered the target density) ÷ (the number of all keys of the unit 2) × 100% is equal to or greater than the set value of the set final printing transition OK%. Determine (step S10). If the calculated value is equal to or greater than the set value of the final printing transition OK%, a pass judgment is made. It is determined whether or not the number of pass determinations has reached the set number of final printing transition determinations (one, two consecutive times, or three consecutive times) (step S11). If it is determined that the result has been reached, the main printing transition OK flag of the unit 2 is set (step S12), and the determination of the unit 3 is performed (step S13). If it is determined that the value has not been reached, the process proceeds to the determination of the unit 3 (step S13). Further, if it is determined in step S10 that the value is less than the set value of the main printing transition OK%, the determination is performed on the unit 3 (step S13). In step S13, the number of keys in which the density value measured for the color printed by the unit 3 enters the target density is calculated (the number of OK keys for the m-th (first) test printing of the unit 3 is calculated).

Next, whether or not the calculated value of (the number of keys of the unit 3 that has entered the target density) ÷ (the number of all keys of the unit 3) × 100% is equal to or greater than the set value of the set final printing transition OK%. Determine (step S14). If the calculated value is equal to or greater than the set value of the final printing transition OK%, a pass judgment is made. It is determined whether or not the number of pass determinations has reached the set number of final printing transition determinations (one, two consecutive times, or three consecutive times) (step S15). If it is determined that the result has been reached, the main printing transition OK flag of the unit 3 is set (step S16), and the determination of the unit 4 is performed (step S17). If it is determined that the value has not been reached, the process proceeds to the determination of the unit 4 (step S17). Further, if it is determined in step S14 that the value is less than the set value of the main printing transition OK%, the determination of the unit 4 is performed (step S17). When the process proceeds to step S17, the number of keys in which the density value measured for the color printed by the unit 4 enters the target density is calculated (the number of OK keys for the mth (first) test printing of the unit 4 is calculated. ).

Next, whether or not the calculated value of (the number of keys of the unit 4 that has entered the target density) ÷ (the number of all keys of the unit 4) × 100% is equal to or greater than the set value of the set final printing transition OK%. Determine (step S18). If the calculated value is equal to or greater than the set value of the final printing transition OK%, a pass judgment is made. It is determined whether or not the number of pass determinations has reached the set number of final printing transition determinations (one, two consecutive times, or three consecutive times) (step S19). If it is determined that the result has been reached, the main printing transition OK flag of the unit 4 is set (step S20), and the determination of the unit n is performed (step S21). If it is determined that the value has not been reached, the process proceeds to the determination of the unit n (step S21). Further, if it is determined in step S18 that the value is less than the set value of the main printing transition OK%, the determination of the unit n proceeds (step S21). When the process proceeds to step S21, the number of keys whose density value measured for the color printed by the unit n is within the target density is calculated (the number of OK keys for the mth (first) trial printing of the unit n is calculated. ).

Next, whether or not the calculated value of (the number of keys of the unit n that has entered the target density) ÷ (the number of all keys of the unit n) × 100% is equal to or greater than the set value of the set final printing transition OK%. Determine (step S22). If the calculated value is equal to or greater than the set value of the final printing transition OK%, a pass judgment is made. It is determined whether or not the number of pass determinations has reached the set number of final printing transition determinations (one, two consecutive times, or three consecutive times) (step S23). If it is determined that the result has been reached, the main printing transition OK flag of the unit n is set (step S24), and the process proceeds to step S25. If it is determined that the value has not been reached, the process proceeds to step S25. If it is determined in step S22 that the value is less than the set value of the main printing transition OK%, the process proceeds to step S25. In step S25, it is determined whether or not the main printing transition OK flag of all the units is set. When it is determined that the main printing transition OK flag of all the units is set, the main printing is performed (step S26). When it is determined that the main printing transition OK flag of all the units is not set, the process returns to step S3 and the m-th test printing (if the previous time is the first time, the second time) is started.

When printing only the front surface (or only the back surface) of the printing paper using the printing machine 1, the number of pass determinations of all the color densities printed on the front surface (or the back surface) is set as the final printing transition determination. When the number of times is reached, the test printing will be shifted to the main printing. Further, when printing on both the front and back surfaces of the printing paper using the printing machine 1, the number of pass judgments of all the color densities printed on both the front and back surfaces is set to the set number of times of pass determination. When the number of judgments is reached, the test printing is shifted to the main printing. In this embodiment, from the start of test printing to the transition to main printing, printing is continued in a state where printing is continued unless a problem such as poor paper feeding occurs.

For example, when the number of main printing transition determinations is set to 2 times in a row and printing is performed only by the unit 1 and the unit 2, the unit 1 is judged to pass the test printing in the first and second times in a row. If the second and third trial prints are rejected after the first trial print is rejected, the unit 1 and the unit 2 are judged to be rejected in the second and third trial prints. Since the flags are set in all of the units 2, the printing will be started. In short, if the flags of all units (all colors) are set, the process shifts to main printing. In this embodiment, regardless of the number of trial printings, the trial printing is performed until the set number of final printing transition determinations (one, two consecutive times, or three consecutive times) is reached. If the number of printings increases, control may be performed so as to automatically reduce the set number of main printing transition determinations. For example, when the number of main printing transition determinations is set to 3 times in a row and the main printing transition OK flag of all units (all colors) is not set by the trial printing (that is, when the main printing does not shift), After the sixth trial printing, the number of main printing transition determinations may be automatically reduced (for example, the setting may be changed to two consecutive times).

The concentration-related index deriving means 15 and the final printing transition means 17 described in the above embodiment can also be configured as follows. That is, the density-related index derivation means 15 is composed of means for deriving the average density value obtained by dividing the total density value of the sum of the density values of the plurality of solid patches by the number of solid patches as the density-related index, and the final printing transition means 17 However, when the difference between the average density value derived by the density-related index deriving means 15 and the target density value, which is the target index, is within the set range, it is determined that the test-printed printed matter is acceptable. When the difference between the average density value derived by the density-related index deriving means 15 and the target density value is outside the set range, it may be a means for determining that the test-printed printed matter has failed.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

In the above embodiment, the printing machine including five units is shown, but it may be a printing machine including one unit or two or more arbitrary number of units. Further, a printing machine including a plurality of units may print with a smaller number of units (at least one unit or more) than the total number of units.

Further, although the RGB camera 6 is used in the above embodiment, a spectrophotometer may be used. In this case, the spectrocolorimeter constitutes a density value measuring means 14 for measuring the density values of a plurality of solid patches.

Further, in the above-described embodiment, the density of all solid patches has been confirmed, but only the density of solid patches corresponding to the areas important in terms of print quality may be confirmed.

1 ... Printing machine, 2 ... Paper stacking table, 3 ... Feeder device, 4 ... Feeding unit, 5 ... Printing unit, 5A, 5B, 5C, 5D, 5E ... Printing unit, 6 ... RGB camera, 7 ... Paper ejection unit , 9 ... Box, 10 ... Step, 11 ... Side wall, 12 ... Button, 13 ... Density value calculation means, 14 ... Concentration value measurement means, 15 ... Concentration-related index calculation means, 16 ... Pass / fail judgment means, 17 ... Main printing Transition means, S ... Control unit

Claims (3)

A density value measuring means for measuring the density value of the test print printed matter during transportation, a pass / fail judgment means for determining whether the test print printed matter passes or fails based on the density value measured by the density value measuring means, and the like. It is provided with a main print transition means for determining whether or not the transition from the test print to the main print is possible based on the pass / fail judgment by the pass / fail judgment means.
The printing press is characterized in that the main printing transfer means is configured as a condition for determining that the transfer to the main printing is possible by a plurality of consecutive pass determinations by the pass / fail determination means. The density value measuring means measures the density value of each of a plurality of solid patches printed in a range corresponding to each ink pot key of a test-printed printed matter, and among the plurality of solid patches, the measured density value is the target density. It is equipped with a concentration-related index derivation means that derives the number of solid patches included in the value as a concentration-related index.
When the density-related index derived by the density-related index deriving means is equal to or greater than the number of targets, which is the target index, the pass / fail determination means determines that the test-printed matter has passed, and the density-related index deriving means. The printing machine according to claim 1, wherein the density-related index derived in 1 is a means for determining that the test-printed matter has failed when the number is less than the target number. The density value measuring means measures the density value of each of a plurality of solid patches printed in a range corresponding to each ink pot key of the test printed matter.
It is equipped with a concentration-related index derivation means for deriving an average concentration value obtained by dividing the total concentration value obtained by totaling the measured concentration values of the plurality of solid patches by the number of solid patches as a concentration-related index.
The pass / fail determination means determines that the test print is acceptable when the difference between the average density value derived by the density-related index deriving means and the target density value, which is the target index, is within the set range. When the difference between the average density value derived by the density-related index deriving means and the target density value is out of the set range, the test-printed matter is determined to be unacceptable. The printing machine according to claim 1.

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