Printing device

Abstract

To provide a printer capable of reducing occurrence of situations in which time for the image inspection to switch a conveyance destination of printing media cannot be guaranteed while restricting enlargement of the device and increase of consumption power.SOLUTION: When an after-reading switch arrival time which is the time from when a reading part 22 reads the image for inspection to when a tip of the sheet P arrives at a switch part 51 in the case that a printing object image is printed on the sheet P in original orientation is less than an inspection time needed from when the reading part 22 reads the image for inspection to when it controls the switch part 51 based on an inspection result of the reading data, a control part 6 controls a printing part 3 so that the after-reading switch arrival time is equal to or longer than the inspection time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a printing device. [Background technology]

[0002] 2. Description of the Related Art Printing devices that print on a print medium and inspect the printed image are known.

[0003] Also, a discharge device is known that switches the destination of the print medium among a plurality of discharge units based on the inspection result of the image printed on the print medium (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-263001 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when the destination of the transported print medium is switched by the switching unit based on the image inspection results, it is necessary to obtain the image inspection results and control the switching unit to switch before the print medium reaches the switching unit.

[0006] Therefore, if the transport path to the switching section is configured to be sufficiently long in order to avoid a situation in which there is not enough time for image inspection before the print medium reaches the switching section, this will result in an increase in the size of the device.

[0007] In contrast, if an existing path, such as a path for turning over the print medium, connected to the transport path of the print medium toward the switching unit is used as a path for buying time, the size of the device can be reduced. In other words, by controlling the print medium to be transported to the switching unit via a path for buying time that is connected to the transport path toward the switching unit, it is possible to ensure time for image inspection while preventing the size of the device from increasing.

[0008] In this case, however, it is necessary to drive rollers for transporting the print medium along the time-buying path, which leads to an increase in power consumption.

[0009] The present invention has been made in consideration of the above, and aims to provide a printing device that can reduce the occurrence of situations where time cannot be secured for image inspection to switch the destination of the printing medium, while suppressing the increase in size of the device and the increase in power consumption. [Means for solving the problem]

[0010] According to one aspect of the present invention, a printing unit that prints an image to be printed, including a test image, on a printing medium, a plurality of stacking units on which the printing media printed by the printing unit are respectively stacked, and a switching unit that switches the destination of the printing media between the plurality of stacking units and transports the printing medium printed by the printing unit to one of the plurality of stacking units, a reading unit that is disposed between the printing unit and the switching unit in the transport direction of the printing medium by the transport unit and reads the test image on the printing medium transported by the transport unit, and a pre-processing unit that performs a pre-processing based on an inspection result of the read data generated by the reading unit reading the test image. and a control unit that controls the switching unit to switch the destination of the printing medium between the multiple loading units, wherein when the image to be printed is printed on the printing medium in its original orientation, a post-reading switching arrival time, which is the time from when the reading unit reads the test image on the printing medium to when the leading edge of the printing medium reaches the switching unit, is less than an inspection time, which is the time required from when the reading unit reads the test image to when it controls the switching unit based on the inspection result, the control unit controls the printing unit so that the post-reading switching arrival time is equal to or greater than the inspection time.

[0011] According to another aspect of the present invention, the present invention includes a printing unit that prints an image to be printed, including a test image, on a printing medium, a plurality of stacking units on which the printing medium printed by the printing unit is respectively stacked, and a transport unit having a switching unit that switches the destination of the printing medium between the plurality of stacking units and transports the printing medium printed by the printing unit to one of the plurality of stacking units, a reading unit that is disposed between the printing unit and the switching unit in the transport direction of the printing medium by the transport unit and reads the test image on the printing medium transported by the transport unit, and a control unit that controls the switching unit to switch the destination of the printing medium between the plurality of stacking units based on an inspection result of the read data generated by the reading unit reading the test image, A printing device is provided in which, when the image to be printed is printed on the printing medium in its original orientation, the control unit controls the printing unit to rotate the image to be printed from its original orientation and print it on the printing medium so that the post-reading switching arrival time is equal to or greater than the inspection time, if the post-reading switching arrival time, which is the time from when the reading unit reads the test image on the printing medium to when the leading edge of the printing medium reaches the switching unit, is less than the inspection time, which is the time from when the reading unit reads the test image to when the reading unit controls the switching unit based on the inspection results, and it is possible to make the post-reading switching arrival time equal to or greater than the inspection time by rotating the image to be printed from its original orientation and printing it on the printing medium. Effect of the Invention

[0012] According to the printing device of the present invention, it is possible to reduce the occurrence of a situation in which time cannot be secured for image inspection in order to switch the transport destination of the print medium, while suppressing an increase in the size of the device and an increase in power consumption. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a printing device according to a first embodiment. [Diagram 2] 10 is a flowchart for explaining the operation of the printing device when printing an image to be printed, including an image for inspection. [Diagram 3]11 is a diagram for explaining a method for calculating a post-reading switching arrival time. FIG. [Figure 4] FIG. 1A is a schematic diagram of an image inspection unit of a printing device according to second and third embodiments, and FIG. 1B is a schematic diagram of a part of a paper discharge unit of the same. [Diagram 5] 4 is an explanatory diagram showing the positional relationship between two reading units of an image inspection unit and two switching units of a paper discharge unit. FIG. [Figure 6] 13 is a flowchart for explaining the operation of the printing device according to the second and third embodiments when the printing device prints a print target image including a test image. [Figure 7] 11 is a diagram for explaining a method for calculating a post-reading switching arrival time. FIG. [Figure 8] 13 is an explanatory diagram showing the positional relationship between two reading units of an image inspection unit and two switching units of a paper discharge unit of a printing device according to a third embodiment. FIG. [Figure 9] 13 is a diagram for explaining a method for calculating a post-scanning switching arrival time in a printing device according to a fourth embodiment. FIG. [Figure 10] 10 is a flowchart for explaining the operation of the printing device when printing an image to be printed, including an image for inspection. [Figure 11] 13 is an explanatory diagram showing the positional relationship between two reading units of an image inspection unit and two switching units of a paper discharge unit of a printing device according to a fifth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same or equivalent parts and components are denoted by the same or equivalent reference numerals throughout the drawings.

[0015] The following embodiments are examples of devices for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the material, shape, structure, arrangement, etc. of each component to those described below. The technical idea of ​​the present invention can be modified in various ways within the scope of the claims.

[0016] 1 is a schematic diagram of a printing device according to a first embodiment of the present invention. In the following description, the top, bottom, left, and right directions on the plane of FIG.

[0017] As shown in FIG. 1, a printing device 1 according to this embodiment includes a paper feed section 2, a printing section 3, an image inspection section 4, a paper discharge section 5, and a control section 6.

[0018] The paper feed section 2 includes a plurality of paper feed trays 11 on which paper sheets (corresponding to print media) P are stacked, and the paper sheets P are fed from the paper feed trays 11 to the printing section 3.

[0019] The printing unit 3 performs printing on the paper P fed from the paper feed unit 2. The printing unit 3 includes a plurality of inkjet heads 16, a circulating conveyance unit 17, and a connecting conveyance unit .

[0020] The inkjet head 16 ejects ink onto the paper P transported by the circulating transport unit 17 to print an image.

[0021] The circulating conveyance section 17 conveys the paper P fed from the paper feed section 2. The circulating conveyance section 17 has an inverting section 19 for inverting the paper P from front to back.

[0022] In the case of face-up ejection single-sided printing, the circulating conveyance section 17 conveys the paper P, one side of which has been printed by the inkjet head 16, to the connecting conveyance section 18 as is.

[0023] In double-sided printing, the circulating transport section 17 transports the paper P, whose front side has been printed by the inkjet head 16, to the inverting section 19, which then inverts the paper and re-feeds it to the inkjet head 16. The circulating transport section 17 then transports the paper P, whose back side has been printed by the inkjet head 16, to the connecting transport section 18. In addition, in face-down discharge, the circulating transport section 17 transports the paper P, whose front side has been printed by the inkjet head 16, to the inverting section 19, which then inverts the paper and re-feeds it to the inkjet head 16. The circulating transport section 17 then transports the printed paper P, whose back side has not been printed and which has passed through the inkjet head 16, to the connecting transport section 18.

[0024] The communication transport section 18 transports the printed paper P from the circulating transport section 17 to the image inspection section 4.

[0025] The image inspection unit 4 reads an inspection image 61 (see FIG. 3) on the paper P printed by the printing unit 3. The image inspection unit 4 includes a reading and conveying unit 21 and two reading units 22a and 22b.

[0026] The reading conveying section 21 conveys the paper P conveyed by the communication conveying section 18 to the paper ejection section 5.

[0027] The reading units 22a and 22b read the test image 61 printed on the paper P transported by the reading and transporting unit 21. The reading units 22a and 22b are configured with a CIS (Contact Image Sensor) or the like. One of the two reading units 22a and 22b, the reading unit 22a, is disposed above the reading and transporting unit 21 and reads the test image 61 on the upper surface of the paper P transported by the reading and transporting unit 21. The other reading unit 22b is disposed below the reading and transporting unit 21 and reads the test image 61 on the lower surface of the paper P transported by the reading and transporting unit 21. The two reading units 22a and 22b are disposed at the same position between the printing unit 3 and the paper discharge unit 5 in the transport direction (left-right direction) of the paper P.

[0028] When the paper P transported by the reading and transporting unit 21 is printed on one side and discharged face up, the paper P is transported from the printing unit 3 to the image inspection unit 4 with the front side Pa, which is the printed side, facing upward. Therefore, in the image inspection unit 4, the front side Pa (see FIG. 3) of the paper P is placed on the upper side, and the back side Pb (see FIG. 3) is placed on the lower side. Therefore, the test image 61 printed on the front side Pa is read by the reading unit 22a (front side reading unit in this case) above.

[0029] When the paper P transported by the reading and transporting unit 21 is double-sided printed or single-sided printed with face-down paper ejection, the paper P is transported from the printing unit 3 to the image inspection unit 4 with the front surface Pa facing downward. Therefore, in the image inspection unit 4, the back surface Pb of the paper P is placed on the upper surface side, and the front surface Pa is placed on the lower surface side. Therefore, the test image 61 printed on the front surface Pa is read by the lower reading unit 22b (the front surface reading unit in this case), and the test image 61 printed on the back surface Pb is read by the upper reading unit 22a (the back surface reading unit in this case).

[0030] The paper discharge section 5 discharges (ejects) the paper P printed by the printing section 3. The paper discharge section 5 includes a paper discharge transport section 31 and stacking sections 32A and 32B.

[0031] The paper discharge conveying unit 31 receives and conveys the paper P conveyed by the reading conveying unit 21, and selectively discharges the paper to the stacking units 32A and 32B. The reading conveying unit 21 and the paper discharge conveying unit 31 constitute a conveying unit that conveys the paper P printed by the printing unit 3 to either the stacking units 32A or 32B.

[0032] The discharge conveying section 31 includes a common discharge path 41, an upstream discharge path 42, a downstream discharge path 43, a reversing path 44, an introduction roller pair 45, a lifting roller pair 46, an upstream discharge conveying roller pair 47, multiple downstream discharge conveying roller pairs 48, a reversing roller pair 49, and switching sections 50 and 51.

[0033] The common sheet discharge path 41 is a transport path common to the sheets P transported to the stacker 32A and the sheets P transported to the stacker 32B.

[0034] The upstream discharge path 42 is connected to the downstream end of the common discharge path 41 in the conveyance direction of the paper P, and is a conveyance path for conveying the paper P to the stacking unit 32A and discharging it.

[0035] The downstream discharge path 43 is connected to the downstream end of the common discharge path 41, and is a transport path for transporting the paper P to the stacking unit 32B and discharging the paper P therefrom.

[0036] The reversing path 44 is a conveying path for switching back the sheet P to reverse it. The reversing path 44 is connected to the common discharge path 41. The reversing path 44 branches off from the common discharge path 41 near the downstream side of the lead-in roller pair 45, and merges with the common discharge path 41 near the upstream side of the lift roller pair 46 on the downstream side of the branching point.

[0037] The lead-in roller pair 45 leads the paper P conveyed by the reading and conveying unit 21 to the paper discharge unit 5. The lead-in roller pair 45 is disposed at the upstream end of the common paper discharge path 41.

[0038] The lifting roller pair 46 transports the paper P transported by the introduction roller pair 45 or the reversing roller pair 49 to the upstream paper discharge transport roller pair 47 or the downstream paper discharge transport roller pair 48. The lifting roller pair 46 is disposed downstream of the introduction roller pair 45 along the common paper discharge path 41.

[0039] The upstream discharge conveying roller pair 47 conveys the paper P conveyed by the lifting roller pair 46 to the stacking unit 32A and discharges the paper P. The upstream discharge conveying roller pair 47 is disposed at the downstream end of the upstream discharge path 42.

[0040] The downstream discharge conveying roller pair 48 conveys the sheet P conveyed by the lifting roller pair 46 to the stacking unit 32B and discharges the sheet P. The downstream discharge conveying roller pair 48 is disposed along the downstream discharge path 43.

[0041] The pair of reversing rollers 49 switches back the sheet P conveyed by the pair of introducing rollers 45 and conveys it to the pair of lifting rollers 46. The pair of reversing rollers 49 is disposed along the reversing path 44.

[0042] The switching unit 50 switches the transport path of the paper P between the common paper discharge path 41 and the reversing path 44 in the vicinity of the downstream side of the pair of introduction rollers 45.

[0043] The switching unit 51 switches the transport path of the paper P on the downstream side of the common paper discharge path 41 between the upstream paper discharge path 42 and the downstream paper discharge path 43. In other words, the switching unit 51 switches the transport destination (discharge destination) of the paper P between the stackers 32A and 32B.

[0044] The stacking sections 32A and 32B are for stacking the printed paper P discharged by the paper discharge conveying section 31. The upstream stacking section 32A stacks and holds the paper P discharged by the upstream paper discharge conveying roller pair 47. The downstream stacking section 32B stacks and holds the paper P discharged by the downstream paper discharge conveying roller pair 48.

[0045] The control unit 6 controls the operation of each unit of the printing device 1. The control unit 6 includes a CPU, a RAM, a ROM, a hard disk, and the like.

[0046] When the control unit 6 prints the image to be printed, including the test image 61, on the paper P, it controls the switching unit 51 to switch the destination of the paper P between the stacking units 32A and 32B based on the inspection results of the read data generated by the reading units 22a and 22b reading the test image 61.

[0047] In addition, when printing the image to be printed including the test image 61, if the post-reading switching arrival time described below when the image to be printed is printed on paper P in its original orientation is less than the inspection time Tk described below, and it is possible to make the post-reading switching arrival time greater than or equal to the inspection time Tk by rotating the image to be printed 180° from its original orientation and printing it on paper P, the control unit 6 controls the printing unit 3 to rotate the image to be printed 180° from its original orientation and print it on paper P so that the post-reading switching arrival time is greater than or equal to the inspection time Tk.

[0048] Here, the original orientation of the image to be printed is the orientation of the image to be printed that is initially set in the print job for printing the image to be printed.

[0049] The post-reading switching arrival time is the time from when the reading units 22a and 22b read the test image 61 of the paper P until the leading edge (downstream end) of the paper P reaches the switching unit 51. Here, the post-reading switching arrival time is basically the time from when the reading units 22a and 22b read the test image 61 of the paper P until the leading edge (downstream end) of the paper P reaches the switching unit 51 in a case where the paper P does not pass through the inversion path 44. In a case where the paper P passes through the inversion path 44, the post-reading switching arrival time is the time from when the reading units 22a and 22b read the test image 61 of the paper P until the leading edge (downstream end) of the paper P reaches the switching unit 51 after passing through the inversion path 44 and being switched back.

[0050] The above-mentioned inspection time Tk is the time required from when the reading units 22a and 22b read the inspection image 61 until the control unit 6 controls the switching unit 51 based on the inspection result of the read data of the inspection image 61. The inspection time Tk includes the time required to inspect (image inspection) the read data of the inspection image 61. The inspection time Tk is a fixed time that is known in advance by the control unit 6.

[0051] The test image 61 is composed of a barcode, etc. The test image 61 includes test information such as information indicating the page order.

[0052] Next, the operation of the printing device 1 when printing an image to be printed, including the test image 61, will be described.

[0053] 2 is a flowchart for explaining the operation of the printing device 1 when printing an image to be printed, including the test image 61. The procedure of the flowchart in FIG. 2 starts when a print job for printing the image to be printed, including the test image 61, is input to the printing device 1.

[0054] In step S1 of FIG. 2, the control unit 6 determines whether or not the post-reading switchover arrival time T1 when the image to be printed is printed on the paper P in the original orientation is equal to or longer than the inspection time Tk.

[0055] Here, the post-reading switching arrival time T1 is expressed by the following formula (1).

[0056] T1=L1 / V …(1) Here, V is the transport speed of the paper P in the common paper discharge path 41 of the reading transport section 21 and the paper discharge transport section 31. The transport speed V is a preset speed.

[0057] As shown in Fig. 3, L1 is the distance between the leading edge (downstream end) of the paper P and the switching unit 51 at the time when the reading of the test image 61 by the reading units 22a and 22b is completed when the image to be printed is printed on the paper P in the original orientation (without rotation). Note that in Fig. 3, portions of the image to be printed other than the test image 61 are omitted from the illustration.

[0058] The distance L1 is expressed by the following formula (2).

[0059] L1 = Lr - Lt1 ... (2) Here, Lr is the distance on the transport path of the paper P between the reading target positions of the reading units 22a and 22b and the switching unit 51, without passing through the reversing path 44. The distance Lr is a fixed value.

[0060] Lt1 is the distance between the leading edge (downstream edge) of the paper P and the trailing edge (upstream edge) of the test image 61 when the image to be printed is printed on the paper P in the original orientation (without rotation).

[0061] The control unit 6 calculates the distance Lt1 based on information included in the print job that indicates the position of the test image 61 in the image to be printed and information that indicates the paper size (paper length in the transport direction). Next, the control unit 6 calculates the post-reading switching arrival time T1 using equations (1) and (2). Then, the control unit 6 determines whether the calculated post-reading switching arrival time T1 is equal to or longer than the inspection time Tk.

[0062] If it is determined that T1≧Tk (step S1: YES), in step S2, the control unit 6 executes a printing operation to print the image to be printed without rotation (in the original orientation) and discharge the paper without passing through the inversion path 44.

[0063] Specifically, the control unit 6 controls the paper P to be sequentially fed from the paper feed unit 2 to the printing unit 3, and controls the printing unit 3 to print the image to be printed, including the test image 61, on the paper P in the original orientation.

[0064] The paper sheets P printed by the printing unit 3 pass through the image inspection unit 4 and are sequentially transported to the paper discharge unit 5. In the image inspection unit 4, the reading unit 22a reads the test image 61 on the upper surface of each paper sheet P that passes sequentially, and the reading unit 22b reads the test image 61 on the lower surface of each paper sheet P to generate respective read data.

[0065] The control unit 6 inspects the read data of the test image 61 of each sheet P, and judges for each sheet P whether the sheet P is a normal print (normal sheet). For example, the control unit 6 analyzes the read data of the test image 61 to obtain information indicated by the test image 61, and if the obtained information is normal, the control unit 6 judges that the sheet P on which the test image 61 is printed is normal sheet. If the information obtained by analyzing the read data of the test image 61 is abnormal, the control unit 6 judges that the sheet P on which the test image 61 is printed is abnormal sheet.

[0066] Then, the control unit 6 controls the switching unit 51 so that normal sheets are discharged to the stacking unit 32A and abnormal sheets are discharged to the stacking unit 32B. Here, the control unit 6 sets the orientation of the switching unit 50 so that the sheet P is conveyed to the switching unit 51 along the common discharge path 41 without passing through the reverse path 44 from the pair of introduction rollers 45.

[0067] Here, since T1≧Tk, before the leading edge of the sheet P reaches the switching unit 51, switching control of the switching unit 51 based on the inspection result of the read data of the inspection image 61 of the sheet P can be performed. That is, it is possible to secure the time for inspecting (image inspection) the read data of the inspection image 61.

[0068] Here, when the inspection image 61 is printed on both sides of the sheet P, it is printed so that the distance Lt1 on the front surface Pa is equal to the distance Lt1 on the back surface Pb. For this reason, the inspection image 61 on the front surface Pa and the inspection image 61 on the back surface Pb of the sheet P are read by the corresponding reading units 22b and 22a at the same timing. If the inspection result of the read data of at least either the inspection image 61 on the front surface Pa or the inspection image 61 on the back surface Pb of the sheet P is abnormal, the sheet P is determined to be an abnormal sheet.

[0069] When the number of sheets P corresponding to the number of prints in the print job is printed by the printing unit 3 and discharged by the discharging unit 5, a series of operations ends.

[0070] In step S1, if it is determined that T1<Tk (step S1: NO), in step S3, the control unit 6 determines whether or not the post-reading switching arrival time T2 when the print target image is printed on the sheet P after being rotated 180° from the original orientation is equal to or longer than the inspection time Tk.

[0071] Here, the post-reading switching arrival time T2 is represented by the following formula (3).

[0072] T2 = L2 / V …(3) 3, L2 is the distance between the leading edge (downstream edge) of the paper P and the switching unit 51 at the time when the reading units 22a and 22b finish reading the test image 61 when the image to be printed is rotated 180° from the original orientation and printed on the paper P. The distance L2 is expressed by the following formula (4).

[0073] L2 = Lr - Lt2 ... (4) Lt2 is the distance between the leading edge (downstream edge) of the paper P and the trailing edge (upstream edge) of the test image 61 when the image to be printed is printed on the paper P rotated 180 degrees from the original orientation.

[0074] The control unit 6 calculates the distance Lt2 based on information indicating the position of the test image 61 in the image to be printed, which is included in the print job, and information indicating the paper size (paper length in the transport direction). Next, the control unit 6 calculates the post-reading switching arrival time T2 using equations (3) and (4). Then, the control unit 6 determines whether the calculated post-reading switching arrival time T2 is equal to or longer than the inspection time Tk.

[0075] If it is determined that T2≧Tk (step S3: YES), in step S4, the control unit 6 executes a printing operation to rotate the image to be printed 180° from the original orientation, print it, and eject it without passing through the inversion path 44.

[0076] The printing operation in step S4 is the same as the printing operation in step S2 described above, except that the image to be printed is rotated 180 degrees from its original orientation and printed.

[0077] Here, since T1 < Tk, it is not possible to perform the switching control of the switching unit 51 based on the inspection result of the read data of the inspection image 61 of the sheet P until the leading edge of the sheet P reaches the switching unit 51. However, since T2 ≥ Tk, by rotating the print target image by 180° from the original orientation and printing, it is possible to perform the switching control of the switching unit 51 based on the inspection result of the read data of the inspection image 61 of the sheet P before the leading edge of the sheet P reaches the switching unit 51 without the sheet P passing through the inversion path 44. That is, by rotating the print target image by 180° from the original orientation and printing, it is possible to secure the time for inspecting the read data of the inspection image 61 (image inspection).

[0078] In step S3, when it is determined that T2 < Tk (step S3: NO), in step S5, the control unit 6 prints the print target image without rotation and executes the printing operation so as to discharge the paper via the inversion path 44.

[0079] In the printing operation of step S5, the control unit 6 sets the orientation of the switching unit 50 so that the sheet P is guided from the introduction roller pair 45 to the inversion path 44. Thereby, the sheet P is conveyed to the switching unit 51 via the inversion path 44 in the discharge conveyance unit 31.

[0080] Here, since T1 < Tk and T2 < Tk, whether the print target image is printed in the original orientation or rotated by 180° from the original orientation, when the sheet P does not pass through the inversion path 44, it is not possible to perform the switching control of the switching unit 51 based on the inspection result of the read data of the inspection image 61 of the sheet P until the leading edge of the sheet P reaches the switching unit 51. That is, even if the print target image is rotated by 180° from the original orientation and printed, when the sheet P does not pass through the inversion path 44, it is not possible to secure the time for inspecting the read data of the inspection image 61 (image inspection).

[0081] When the paper P passes through the inversion path 44, the distance that the paper P is transported becomes longer and a switchback operation is performed, compared to when the paper P does not pass through the inversion path 44. Therefore, when the paper P passes through the inversion path 44, the post-reading switch arrival time becomes longer than the inspection time Tk, regardless of the position of the test image 61 on the paper P.

[0082] Therefore, in the printing operation of step S5, the control unit 6 controls the discharge conveying unit 31 to convey the paper P to the switching unit 51 via the inversion path 44 as described above. In other words, the existing inversion path 44 is used as a path for buying time. This makes the post-reading switching arrival time equal to or longer than the inspection time Tk. As a result, by the time the leading edge of the paper P reaches the switching unit 51, it becomes possible to control the switching of the switching unit 51 based on the inspection result of the read data of the test image 61 of the paper P.

[0083] In the printing operation in step S5, the image to be printed may be rotated 180 degrees from its original orientation and printed.

[0084] As described above, in the printing device 1, when printing the image to be printed including the test image 61, if the post-reading switching arrival time when the image to be printed is printed on the paper P in its original orientation is less than the inspection time Tk and it is possible to make the post-reading switching arrival time equal to or greater than the inspection time Tk by rotating the image to be printed 180° from its original orientation and printing it on the paper P, the control unit 6 controls the printing unit 3 to rotate the image to be printed 180° from its original orientation and print it on the paper P so that the post-reading switching arrival time is equal to or greater than the inspection time Tk.

[0085] This makes it possible to reduce the occurrence of a situation in which time for image inspection cannot be secured without configuring an excessively long transport path from the reading units 22a and 22b to the switching unit 51. Also, it is possible to reduce the occurrence of a situation in which time for image inspection cannot be secured without using the reversing path 44 as a path for buying time. Therefore, it is possible to reduce the occurrence of a situation in which time for image inspection cannot be secured while suppressing an increase in the size of the device and an increase in power consumption that occurs when the reversing path 44 is used as a path for buying time.

[0086] Furthermore, in the printing device 1, if the post-reading switching arrival time when the image to be printed is printed on paper P in its original orientation is less than the inspection time Tk, and if the post-reading switching arrival time cannot be made greater than or equal to the inspection time Tk even when the image to be printed is rotated 180 degrees from its original orientation and printed on paper P, the control unit 6 controls the paper discharge conveying unit 31 to convey the paper P to the switching unit 51 via the inversion path 44, thereby controlling the post-reading switching arrival time to be greater than or equal to the inspection time Tk.

[0087] As a result, even if the post-reading switchover arrival time cannot be made equal to or longer than the inspection time Tk even if the image to be printed is rotated 180° from the original orientation and printed on the paper P, it is possible to secure time for image inspection by gaining time on the reversing path 44. As a result, it is possible to avoid stopping the transport of the paper P because it is not possible to secure time for image inspection.

[0088] In addition, if the post-reading switching arrival time when the image to be printed is printed on the paper P in the original orientation is less than the inspection time Tk, and if the post-reading switching arrival time cannot be made equal to or greater than the inspection time Tk even when the image to be printed is rotated 180° from the original orientation and printed on the paper P, the post-reading switching arrival time may be made equal to or greater than the inspection time Tk by controlling the conveying speed of the paper P in the paper discharge conveyance section 31 to be adjusted. In this case, the paper P may or may not pass through the reversal path 44 in the paper discharge conveyance section 31.

[0089] In addition, if the post-reading switching arrival time when the image to be printed is printed on paper P in its original orientation is less than the inspection time Tk, and if the post-reading switching arrival time cannot be made equal to or greater than the inspection time Tk even when the image to be printed is rotated 180 degrees from its original orientation and printed on paper P, the post-reading switching arrival time may be made equal to or greater than the inspection time Tk by controlling the printing unit 3 to adjust the position of the inspection image 61 in the image to be printed and print it.

[0090] That is, when the post-reading switching arrival time when the image to be printed is printed on the paper P in the original orientation is less than the inspection time Tk, the control unit 6 may control the printing unit 3 so that the post-reading switching arrival time is equal to or greater than the inspection time Tk. Specifically, when the post-reading switching arrival time when the image to be printed is printed on the paper P in the original orientation is less than the inspection time Tk, if the post-reading switching arrival time can be made equal to or greater than the inspection time Tk by rotating the image to be printed 180° from the original orientation and printing it on the paper P, the control unit 6 may control the printing unit 3 to rotate the image to be printed 180° from the original orientation and print it on the paper P so that the post-reading switching arrival time is equal to or greater than the inspection time Tk, and when the post-reading switching arrival time cannot be made equal to or greater than the inspection time Tk even if the image to be printed is rotated 180° from the original orientation and printed on the paper P, the control unit 6 may control the printing unit 3 to adjust the position of the test image 61 in the image to be printed and print it.

[0091] Two or three of the above-mentioned control of conveying the paper P to the switching unit 51 via the inversion path 44 in the paper discharge conveyance unit 31, control of adjusting the conveyance speed of the paper P in the paper discharge conveyance unit 31, and control of adjusting and printing the position of the test image 61 in the image to be printed may be combined. That is, if the post-reading switch arrival time when the image to be printed is printed on the paper P in the original orientation is less than the inspection time Tk, and the post-reading switch arrival time cannot be made equal to or longer than the inspection time Tk even if the image to be printed is rotated 180° from the original orientation and printed on the paper P, the post-reading switch arrival time may be controlled to be equal to or longer than the inspection time Tk by at least one of the control of conveying the paper P to the switching unit 51 via the inversion path 44 in the paper discharge conveyance unit 31, control of adjusting the conveyance speed of the paper P in the paper discharge conveyance unit 31, and control of adjusting and printing the position of the test image 61 in the image to be printed.

[0092] Next, a printer 1 according to a second embodiment of the present invention will be described. As shown in Fig. 4(a) and (b), the printer 1 according to this embodiment has an image inspection unit 4 and a paper discharge unit 5 configured differently from the printer 1 according to the first embodiment shown in Fig. 1.

[0093] In the image inspection unit 4 of this embodiment shown in FIG. 4(a), the positions of the reading units 22a and 22b are different in the conveying direction (left-right direction) of the paper P by the reading and conveying unit 21. The reading unit 22a above the reading and conveying unit 21 is disposed at a position closer to the printing unit 3 in the image inspection unit 4. The reading unit 22b below the reading and conveying unit 21 is disposed at a position closer to the paper discharge unit 5 in the image inspection unit 4. The paper P conveyed from the printing unit 3 to the image inspection unit 4 is conveyed by the reading and conveying unit 21 and passes below the reading unit 22a, and then passes above the reading unit 22b. The timing at which the reading units 22a and 22b read the test image 61 of the paper P is after the paper P has been conveyed to the paper discharge unit 5 side by the lower reading unit 22b, compared to the upper reading unit 22a.

[0094] 4(b) further includes a purge discharge path 52 and a switching unit 53. The purge discharge path 52 branches off from the downstream discharge path 43 and extends above the discharge unit 5. The purge discharge path 52 is a transport path for transporting the paper P from the downstream discharge path 43 to a purge discharge section (not shown) above the discharge unit 5 for discharge.

[0095] The switching unit 53 switches the transport path of the paper P between the further part of the downstream paper discharge path 43 continuing to the stacking unit 32B and the purge paper discharge path 52 in the middle of the downstream paper discharge path 43.

[0096] The paper sheets P printed by the printing unit 3 pass through the image inspection unit 4 and are sequentially transported to the paper discharge unit 5. In the image inspection unit 4, the reading unit 22a reads the test image 61 on the upper surface of each paper sheet P that passes sequentially, and the reading unit 22b reads the test image 61 on the lower surface of each paper sheet P to generate respective read data.

[0097] The control unit 6 inspects the read data of the test image 61 of each sheet P, and judges whether or not the sheet P is a normal printed matter (normal paper) for each sheet P. For example, the control unit 6 analyzes the read data of the reading units 22a and 22b that read the test image 61, and acquires information indicated by the test image 61.

[0098] When the test image 61 is read by either one of the reading units 22a, 22b, if the information acquired by the other reading unit 22a, 22b is normal, the control unit 6 determines that the paper P on which the test image 61 is printed is normal paper. If the information acquired by the other reading unit 22a, 22b is abnormal, the control unit 6 determines that the paper P on which the test image 61 is printed is abnormal paper.

[0099] When the test image 61 is read by both the reading units 22a and 22b, if the information acquired by both the reading units 22a and 22b is normal, the control unit 6 determines that the paper P on which the test image 61 is printed is normal paper. If the information acquired by only one of the reading units 22a and 22b is abnormal, the control unit 6 determines that the paper P on which the test image 61 is printed is abnormal paper.

[0100] Then, the control unit 6 controls the switching unit 51 or the switching unit 53 so that normal sheets are discharged to the stacking unit 32A or the stacking unit 32B, and abnormal sheets are discharged to a purge discharge unit (not shown). Here, the control unit 6 can control the switching unit 51 or the switching unit 53 so that normal sheets are discharged to the stacking unit 32A until the number of discharged sheets reaches a specified number, and normal sheets after the number of discharged sheets exceeds the specified number are discharged to the stacking unit 32B.

[0101] The specified number may be, for example, the maximum number of sheets that can be loaded on the stacking section 32A (e.g., 4000 sheets). The specified number may also be, for example, the number of sheets to be discharged from the stacking section 32A designated by the user. The number of sheets to be discharged may be designated in advance, for example, in the print settings of the print job. The control section 6 sets the orientation of the switching section 50 so that the paper P is transported from the lead-in roller pair 45 to the switching section 51 along the common paper discharge path 41 without passing through the reversing path 44.

[0102] 1 is conveyed to the common discharge path 41 of the discharge unit 5 via the reading conveyance unit 21 of the image inspection unit 4. If the paper P does not need to be turned over, the paper P is conveyed by the switching unit 50 from the common discharge path 41 to the upstream discharge path 42 via the shortest route that does not pass through the reversal path 44, and then conveyed to the switching unit 51.

[0103] As shown in FIG. 5, the paper P being transported through the shortest path is transported in the order of the reading unit 22a above the reading transport unit 21, the reading unit 22b below the reading transport unit 21, and the switching unit 51. The control unit 6 controls the switching unit 51, for example, until the number of normal sheets discharged to the stacking unit 32A reaches a specified number. The switching unit 51 transports normal sheets to the upstream paper discharge path 42 and discharges them to the stacking unit 32A, and transports abnormal sheets to the downstream paper discharge path 43 and discharges them to a purge paper discharge unit (not shown) via the purge paper discharge path 52. Here, the control unit 6 sets the direction of the switching unit 53 so that the abnormal sheets transported to the downstream paper discharge path 43 are transported to the purge paper discharge unit (not shown) to be transported to the purge paper discharge path 52.

[0104] Furthermore, for example, after the number of normal sheets discharged to stacker 32A exceeds a specified number, controller 6 controls switching unit 53. Here, controller 6 sets the orientation of switching unit 51 so that sheet P transported to common discharge path 41 is transported to downstream discharge path 43. Switching unit 53 transports normal sheets to the end of downstream discharge path 43 and discharges them to stacker 32B, and transports abnormal sheets to purge discharge path 52 and discharges them to a purge discharge unit (not shown).

[0105] On the transport path of the paper P, which is transported from the printing unit 3 through the image inspection unit 4 to the discharge path after the common discharge path 41 via the shortest route without passing through the inversion path 44, the reading unit 22a and the reading unit 22b are separated by a distance L11, the reading unit 22b and the switching unit 51 are separated by a distance L12, and the switching unit 51 and the switching unit 53 are separated by a distance L13.

[0106] When the paper P transported from the printing unit 3 to the switching unit 51 or switching unit 53 via the shortest route has been printed on one side with face-up ejection, the reading unit 22a (the surface reading unit in this case) of the image inspection unit 4 reads the test image 61 printed on the surface Pa that is placed on the upper side of the paper P.

[0107] When the paper P conveyed to the switching unit 51 or the switching unit 53 is double-sided printed or single-sided printed with face-down paper ejection, in the image inspection unit 4, the reading unit 22b (the front reading unit in this case) of the image inspection unit 4 reads the test image 61 printed on the front surface Pa arranged on the lower surface side of the paper P. Also, the reading unit 22a (the back surface reading unit in this case) reads the test image 61 printed on the back surface Pb arranged on the upper surface side of the paper P.

[0108] When the control unit 6 prints the image to be printed, including the test image 61, on the paper P, it controls the switching unit 51 or the switching unit 53 to switch the destination of the paper P based on the inspection results of the read data generated by at least one of the reading units 22a and 22b reading the test image 61.

[0109] Furthermore, when printing the image to be printed including the test image 61, if the post-reading switching arrival time T1 when the image to be printed is printed on the paper P in its original orientation is less than the inspection time Tk, the control unit 6 determines whether it is possible to make the post-reading switching arrival time T2 equal to or greater than the inspection time Tk by rotating the image to be printed 180° from its original orientation and printing it on the paper P. Then, if it is possible to make the post-reading switching arrival time T2 equal to or greater than the inspection time Tk by rotating the image to be printed 180°, the control unit 6 controls the printing unit 3 to rotate the image to be printed 180° from its original orientation and print it on the paper P so that the post-reading switching arrival time T2 is equal to or greater than the inspection time Tk.

[0110] The inspection time Tk is the time required from when the reading units 22a and 22b read the test image 61 until the control unit 6 controls the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the test image 61.

[0111] Next, the operation of the printing device 1 when printing an image to be printed including the test image 61 will be described. FIG. 6 is a flowchart for explaining the operation of the printing device 1 when printing an image to be printed including the test image 61. The flowchart in FIG. 6 also serves as a flowchart for explaining the operation of the printing device 1 when printing an image to be printed including the test image 61 in the printing device 1 according to a third embodiment described later. For this reason, some steps in the flowchart in FIG. 6 include both the operation performed by the printing device 1 of the second embodiment and the operation performed by the printing device 1 of the third embodiment. The operation according to the procedure in the flowchart in FIG. 6 is started when a print job for printing an image to be printed including the test image 61 is input to the printing device 1.

[0112] 6, when a print job for printing the image to be printed including the test image 61 is input to the printing device 1, the control unit 6 starts printing the image to be printed including the test image 61. In the next step S12, the control unit 6 calculates the post-reading switching arrival time (transport time) T1 when the image to be printed is printed on the paper P in the original orientation.

[0113] When the image to be printed is printed on the paper P in the original orientation (without rotation), the post-reading switching arrival time T1 is expressed by the following formula (5).

[0114] T1=L21 / V …(5) V is the transport speed of the paper P transported from the printing unit 3 to the switching unit 51 or 53 via the shortest route.

[0115] As shown in Figure 7, L21 is the distance between the leading edge (downstream end) of the paper P and the switching unit 51 or switching unit 53 controlled by the control unit 6 at the time when the reading of the test image 61 by the reading units 22a and 22b is completed when the image to be printed is printed on the paper P in its original orientation (not rotated).

[0116] The distance L21 is expressed by the following formula (6).

[0117] L21 = L - Lt1 … (6) Here, L is the distance on the transport path of the paper P between the reading position of the reading units 22a and 22b that read the test image 61 and the switching unit 51 or switching unit 53 that is controlled by the control unit 6, without passing through the reversing path 44. Lt1 is the distance between the leading edge (downstream edge) of the paper P and the trailing edge (upstream edge) of the test image 61 when the image to be printed is printed on the paper P in the original orientation (without rotation).

[0118] The control unit 6 calculates the distance Lt1 based on information included in the print job that indicates the position of the test image 61 in the image to be printed and information that indicates the paper size (paper length in the transport direction).

[0119] When the test image 61 is printed on both sides of the paper P, the control unit 6 calculates the post-reading switching arrival time T1 for both sides of the paper P, respectively.

[0120] In the next step S13, the control unit 6 calculates the post-reading switch arrival time (transport time) T2 in the case where the image to be printed is printed on the paper P while being rotated 180 degrees from the original orientation.

[0121] When an image to be printed is rotated 180 degrees from its original orientation and printed on paper P, the post-reading switching arrival time T2 is expressed by the following formula (7).

[0122] T2=L22 / V …(7) As shown in Figure 7, L22 is the distance between the leading edge (downstream end) of the paper P and the switching unit 51 or switching unit 53 controlled by the control unit 6 at the time when the reading of the test image 61 by the reading units 22a and 22b is completed when the image to be printed is rotated 180° from its original orientation and printed on the paper P.

[0123] The distance L22 is expressed by the following formula (8).

[0124] L22 = L - Lt2 ... (8) Lt2 is the distance between the leading edge (downstream edge) of the paper P and the trailing edge (upstream edge) of the test image 61 when the image to be printed is printed on the paper P rotated 180 degrees from the original orientation.

[0125] The control unit 6 calculates the distance Lt2 based on information included in the print job that indicates the position of the test image 61 in the image to be printed and information that indicates the paper size (paper length in the transport direction).

[0126] Next, in step S14, the control unit 6 determines whether the post-reading switchover arrival time T1 when the image to be printed is printed on the paper P in the original orientation (without rotation) is equal to or greater than the inspection time Tk.

[0127] If it is determined that T1≧Tk (step S14: YES), in step S15, the control unit 6 determines the control content of the printing operation so that the image to be printed is printed without rotation (in the original orientation) and is discharged without passing through the reversal path 44. Specifically, the control unit 6 determines the control content so that the paper P is sequentially fed from the paper feed unit 2 to the printing unit 3, and the image to be printed, including the test image 61, is printed on the paper P in the original orientation in the printing unit 3.

[0128] The paper sheets P printed by the printing unit 3 pass through the image inspection unit 4 and are sequentially transported to the paper discharge unit 5. In the image inspection unit 4, the reading unit 22a reads the test image 61 on the upper surface of each paper sheet P that passes sequentially, and the reading unit 22b reads the test image 61 on the lower surface of each paper sheet P to generate respective read data.

[0129] The control unit 6 inspects the read data of the test image 61 of each sheet P, and judges whether or not each sheet P is a normal printed matter (normal sheet). Then, the control unit 6 controls the switching unit 51 or the switching unit 53 so that normal sheets are discharged to the stacking unit 32A or the stacking unit 32B, and abnormal sheets are discharged to the purge sheet discharge unit.

[0130] Here, since T1≧Tk, before the leading edge of the sheet P reaches the switching unit 51 or the switching unit 53 to be controlled, switching control of the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the inspection image 61 of the sheet P can be performed. That is, the time for inspecting (image inspection) the read data of the inspection image 61 can be ensured.

[0131] Here, when the inspection images 61 are printed on both sides of the sheet P, they are printed so that the distance Lt1 on the front surface Pa is equal to the distance Lt1 on the back surface Pb. For this reason, the inspection image 61 on the front surface Pa and the inspection image 61 on the back surface Pb of the sheet P are read by the corresponding reading units 22b and 22a at different timings. If the inspection result of the read data of at least any one of the inspection image 61 on the front surface Pa and the inspection image 61 on the back surface Pb of the sheet P is abnormal, the sheet P is determined to be an abnormal sheet.

[0132] In step S14, when it is determined that T1<Tk (step S14: NO), in step S16, the control unit 6 determines whether the post-reading switching arrival time T2 when the print target image is printed on the sheet P after being rotated 180° from the original orientation is equal to or greater than the inspection time Tk.

[0133] When it is determined that T2≧Tk (step S16: YES), in step S17, the control unit 6 determines the control content of the printing operation so as to print the print target image after rotating it 180° from the original orientation and discharge the paper without passing through the inversion path 44. The printing operation according to the control content in step S17 is the same as the printing operation in step S15 described above, except that the print target image is printed after being rotated 180° from the original orientation. The description of "or front-back inversion" in step S17 relates to the procedure of the operation performed by the printing apparatus 1 of the third embodiment, and thus will not be described here.

[0134] Here, since T1 < Tk, before the leading edge of the sheet P reaches the switching unit 51 or the switching unit 53 that is the control target of the control unit 6, switching control of the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the inspection image 61 of the sheet P cannot be performed. However, since T2 ≥ Tk, by rotating the print target image by 180° from its original orientation and printing, even if the sheet P does not pass through the reverse path 44, before the leading edge of the sheet P reaches the switching unit 51 or the switching unit 53 that is the control target, switching control of the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the inspection image 61 of the sheet P is possible. That is, by rotating the print target image by 180° from its original orientation and printing, it is possible to secure the time for inspecting (image inspection) the read data of the inspection image 61.

[0135] In step S16, when it is determined that T2 < Tk (step S16: NO), in step S18, the control unit 6 determines the control content of the printing operation to print the print target image without rotation and discharge the paper P by changing at least one of the conveyance path and the conveyance speed of the paper P. The change in the conveyance path can be, for example, a change that increases the conveyance distance of the paper P by conveying the paper P from the common discharge path 41 of the discharge unit 5 via the reverse path 44 to the upstream discharge path 42. The change in the conveyance speed can be, for example, a change that decreases the conveyance speed of the paper P in the discharge conveyance unit 31 by decreasing the conveyance speed in each of the paths 41 to 44 and 52 of the discharge conveyance unit 31 of the discharge unit 5.

[0136] When increasing the conveyance distance of the paper P in step S18, the control unit 6 sets the orientation of the switching unit 50 so that the paper P is guided from the roller pair 45 to the reverse path 44. Thereby, in the discharge conveyance unit 31, the paper P is conveyed to the switching unit 51 or the switching unit 53 via the reverse path 44.

[0137] When decreasing the conveyance speed of the paper P in the discharge conveyance unit 31 in step S18, the control unit 6 decreases the rotation speed of the roller pairs 45 to 49. Thereby, in the discharge conveyance unit 31, the paper P is conveyed at a speed slower than normal.

[0138] Here, since T1 < Tk and T2 < Tk, even if the print target image is printed in its original orientation or rotated 180° from its original orientation, until the leading edge of the paper P reaches the switching unit 51, switching control of the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the inspection image 61 of the paper P cannot be performed. That is, even if the print target image is printed after being rotated 180° from its original orientation, the time for inspecting (image inspection) the read data of the inspection image 61 cannot be ensured.

[0139] When the paper P passes through the reversing path 44, the distance that the paper P is conveyed becomes longer compared to the case where it does not pass through the reversing path 44, and a switchback operation is performed. For this reason, when the paper P passes through the reversing path 44, regardless of the position of the inspection image 61 on the paper P, the post-reading switching arrival time becomes longer than the inspection time Tk.

[0140] When reducing the rotation speed of the roller pairs 45 to 49, the time required to convey the paper P in the paper discharge conveyance unit 31 becomes longer compared to the case where the rotation speed of the roller pairs 45 to 49 is not reduced. For this reason, when reducing the rotation speed of the roller pairs 45 to 49, regardless of the position of the inspection image 61 on the paper P, the post-reading switching arrival time becomes longer than the inspection time Tk.

[0141] Therefore, in step S18, as described above, the control unit 6 controls the paper discharge conveyance unit 31 to convey the paper P to the switching unit 51 via the reversing path 44. Alternatively, the control unit 6 controls the paper discharge conveyance unit 31 to convey the paper P at a speed slower than normal. Or, the control unit 6 controls the paper discharge conveyance unit 31 to convey the paper P to the switching unit 51 or the switching unit 53 via the reversing path 44 at a speed slower than normal.

[0142] That is, the existing reversing path 44 is used as a path for buying time, or the conveying speed of the paper P in the paper discharge conveying unit 31 is reduced to buy time. This makes the post-reading switch arrival time equal to or longer than the inspection time Tk. As a result, by the time the leading edge of the paper P reaches the switching unit 51 or the switching unit 53, it becomes possible to control the switching of the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the test image 61 of the paper P.

[0143] In step S18, the control unit 6 may perform control so as to rotate the image to be printed 180 degrees from its original orientation before printing.

[0144] In step S19 following steps S15, S17, and S18, the control unit 6 determines whether or not the discharge destination of normal paper is to be switched from stacking unit 32A to stacking unit 32B. The description of "or switching of reading unit" in step S19 relates to the procedure of the operation performed by the printing device 1 of the third embodiment, and therefore will not be described here.

[0145] When the discharge destination of normal sheets is switched from stacking section 32A to stacking section 32B, the distance L (see FIG. 7) used to calculate distances L11 and L12 in equations (5) and (7) changes. In this embodiment, when the number of sheets discharged to stacking section 32A reaches a specified number, the discharge destination of normal sheets is switched from stacking section 32A to stacking section 32B, so that control section 6 can determine whether or not the discharge destination of normal sheets will be switched depending on whether the number of sheets discharged to stacking section 32A has reached the specified number.

[0146] If the discharge destination of normal paper is to be switched (step S19: YES), in step S20, the control unit 6 changes the distance L used to calculate the distances L11 and L12 in formulas (5) and (7) to match the discharge destination after the switch (e.g., stacker 32B), and returns to step S12. If the discharge destination of normal paper is not to be switched (step S19: NO), in step S21, the control unit 6 executes the printing operation according to the control contents of steps S15, S17, and S18 as is.

[0147] When the number of sheets P corresponding to the number of sheets to be printed in the print job is printed by the printing unit 3 and discharged by the paper discharge unit 5, a series of operations is completed.

[0148] In the printing device 1 of the second embodiment described above, when printing an image to be printed including a test image 61, if the post-reading switching arrival time when the image to be printed is printed on paper P in its original orientation is less than the inspection time Tk, the control unit 6 determines whether it is possible to make the post-reading switching arrival time equal to or greater than the inspection time Tk by rotating the image to be printed 180° from its original orientation and printing it on paper P. Then, if it is possible to make the post-reading switching arrival time equal to or greater than the inspection time Tk by rotating the image to be printed 180°, the control unit 6 controls the printing unit 3 to rotate the image to be printed 180° from its original orientation and print it on paper P so that the post-reading switching arrival time is equal to or greater than the inspection time Tk.

[0149] This makes it possible to reduce the occurrence of a situation in which time for image inspection cannot be secured without configuring an excessively long transport path from the reading units 22a and 22b to the switching unit 51 or the switching unit 53. Also, even if the reversing path 44 is not used as a path for buying time, it is possible to reduce the occurrence of a situation in which time for image inspection cannot be secured.

[0150] Also, in the printing device 1 of this embodiment, if the post-reading switching arrival time is less than the inspection time Tk when the image to be printed is printed on the paper P in the original orientation and the post-reading switching arrival time cannot be made equal to or greater than the inspection time Tk even when the image to be printed is rotated 180° from the original orientation and printed on the paper P, the control unit 6 performs the following control. That is, the control unit 6 controls the paper P to be conveyed to the switching unit 51 or the switching unit 53 via the reversing path 44 in the paper discharge conveying unit 31, or to convey the paper P by reducing the conveying speed in the paper discharge conveying unit 31, or to convey the paper P by performing both of these, thereby controlling the paper P to be conveyed, so that the post-reading switching arrival time is equal to or greater than the inspection time Tk.

[0151] As a result, even if the post-reading switchover arrival time cannot be made equal to or longer than the inspection time Tk even if the image to be printed is rotated 180° from the original orientation and printed on the paper P, time can be gained on the reversing path 44 or by slowing down the conveying speed, thereby ensuring time for image inspection. As a result, it is possible to avoid stopping the conveyance of the paper P because it is not possible to ensure time for image inspection.

[0152] If the post-reading switching arrival time when the image to be printed is printed on paper P in its original orientation is less than the inspection time Tk, and if the post-reading switching arrival time cannot be made equal to or greater than the inspection time Tk even when the image to be printed is rotated 180° from its original orientation and printed on paper P, the control unit 6 may perform the following control. That is, the control unit 6 may control the printing unit 3 to adjust and print the position of the test image 61 in the image to be printed, thereby making the post-reading switching arrival time equal to or greater than the inspection time Tk.

[0153] It is also possible to combine two or three of the following controls: control to transport paper P to switching unit 51 or switching unit 53 via inversion path 44 in the above-mentioned paper discharge transport unit 31; control to adjust the transport speed of paper P in the paper discharge transport unit 31; and control to adjust the position of the test image 61 in the image to be printed and print it.

[0154] The printer 1 of the second embodiment can also obtain the same effect as the printer 1 of the first embodiment. That is, it is possible to reduce the occurrence of a situation in which time for image inspection cannot be secured while suppressing an increase in the size of the device and an increase in power consumption that occurs when the reversing path 44 is used as a path for buying time.

[0155] Next, a printing device 1 according to a third embodiment of the present invention will be described. The printing device 1 of this embodiment includes a paper feed unit 2, a printing unit 3, an image inspection unit 4, and a paper discharge unit 5, which have the same structures as the printing device 1 of the second embodiment shown in Figures 1 and 4(a) and (b). In the printing device 1 of this embodiment, part of the content of the process performed by the control unit 6 is different from that of the control unit 6 of the printing device 1 of the second embodiment.

[0156] In this embodiment, when printing an image to be printed including a test image 61, if the post-reading switching arrival time when the image to be printed is printed on paper P in its original orientation is less than the inspection time Tk, and if the post-reading switching arrival time can be made greater than or equal to the inspection time Tk by printing the image to be printed front to back on paper P, the control unit 6 controls the printing unit 3 to print the image to be printed back to back on paper P so that the post-reading switching arrival time is greater than or equal to the inspection time Tk.

[0157] Here, printing the image to be printed on paper P by reversing the front and back of the paper P means printing the image to be printed that is originally printed on the front surface Pa of the paper P on the back surface Pb, and printing the image to be printed that is originally printed on the back surface Pb on the front surface Pa.

[0158] 4(a), in the image inspection unit 4 of this embodiment, the positions of the reading units 22a and 22b are different in the transport direction (left-right direction) of the paper P by the reading and conveying unit 21. The position of the paper P when the upper reading unit 22a of the reading and conveying unit 21 reads the test image 61 on the upper surface of the paper P is a position closer to the paper P (upstream) in the transport direction than the position of the paper P when the lower reading unit 22b of the reading and conveying unit 21 reads the test image 61 on the lower surface of the paper P. The timing at which the lower reading unit 22b reads the test image 61 on the paper P is delayed from the timing at which the upper reading unit 22a reads the test image 61 on the paper P.

[0159] When the control target of the control unit 6 is the switching unit 51, at the point in time when the lower reading unit 22b reads the test image 61, the distance between the leading edge (downstream edge) of the paper P and the switching unit 51 becomes a distance L31 as shown in Fig. 8. The distance L31 is the total distance L12 between the reading unit 22b and the switching unit 51 minus the distance Lt11 between the leading edge (downstream edge) of the paper P and the trailing edge (upstream edge) of the test image 61. In this case, the post-reading switching arrival time T1 is expressed by the following formula (9) using the transport speed V of the paper P transported from the printing unit 3 to the switching unit 51 via the shortest route.

[0160] T1=L31 / V …(9) When the control target of the control unit 6 is the switching unit 51, the distance between the leading edge (downstream edge) of the paper P and the switching unit 51 is the distance L32 at the time when the upper reading unit 22a reads the test image 61. The distance L32 is the sum of the distance L11 between the reading unit 22a and the reading unit 22b and the distance L12 between the reading unit 22a and the switching unit 51, minus the distance Lt11 between the leading edge (downstream edge) of the paper P and the rear edge (upstream edge) of the test image 61. This distance L32 is longer than the distance L31 when the reading unit 22b reads the test image 61 by the distance L11 between the reading unit 22a and the reading unit 22b. In this case, the post-reading switching arrival time T2 is expressed by the following formula (10) using the transport speed V of the paper P transported from the printing unit 3 to the switching unit 51 via the shortest route.

[0161] T2=L32 / V …(10) For example, paper P with a print target image printed on its front surface Pa by double-sided printing or single-sided printing with face-down paper ejection is transported with front surface Pa facing down by reading and transporting unit 21, as shown in the upper part of Fig. 8. A test image 61 on this paper P is read by reading unit 22b (front surface reading unit in this case) below. When the leading edge (downstream end) of this paper P is transported a further distance L31 from the point where test image 61 is read, it reaches switching unit 51.

[0162] Also, for example, a sheet of paper P on which a print target image is printed on its front surface Pa by single-sided printing with face-up paper ejection is transported by the reading and transporting unit 21 with the front surface Pa facing up, as shown in the lower part of Fig. 8. A test image 61 on this sheet of paper P is read by the upper reading unit 22a (front surface reading unit in this case). The leading edge (downstream end) of this sheet of paper P reaches the switching unit 51 when it is transported a distance L32, which is longer than the distance L31, from the point at which the test image 61 is read.

[0163] In this way, when the image to be printed including the test image 61 is present on only one side of the paper P, the side on which the test image 61 is printed can be either the front side Pa or the back side Pb. Therefore, in the printing device 1 of this embodiment, the side on which the image to be printed of the paper P is printed is printed on the side opposite to the original side as necessary, so that the post-reading switching arrival time is equal to or longer than the test time Tk.

[0164] In the case where the control target of the control unit 6 is the switching unit 53, the distance between the leading edge (downstream end) of the paper P and the switching unit 53 at the time when the reading units 22a and 22b read the test image 61, respectively, is the above-mentioned distances L31 and L32 plus the distance L13 between the switching units 51 and 53. Furthermore, by dividing this distance by the transport speed V of the paper P, the post-reading switch arrival times T1 and T2 can be obtained. The leading edge (downstream end) of the paper P, whose test image 61 has been read by the reading units 22a and 22b, respectively, reaches the switching unit 53 when it is transported a distance that is the sum of the distance L31 and L32 plus the distance L13 from the time when the test image 61 was read.

[0165] The operational procedure performed by the printing device 1 of this embodiment is shown in the flowchart of Fig. 6. However, the specific content of some procedures differs slightly from that of the printing device 1 of the second embodiment. Below, the operational procedure performed by the printing device 1 of this embodiment will be explained, focusing on the procedures that differ from the second embodiment. Note that in the following explanation, it is assumed that the operation according to the procedure of the flowchart of Fig. 6 starts when a print job is input to the printing device 1 for printing the image to be printed, including the test image 61, on the front surface Pa by double-sided printing or single-sided printing with face-down paper output.

[0166] After starting printing of the image to be printed including the test image 61 in step S11, the control unit 6 calculates in step S12 the post-reading switching arrival time T1 when the image to be printed is printed on the paper P in its original orientation (without rotation) using the above-mentioned formula (9). In addition, in step S13, the control unit 6 calculates the post-reading switching arrival time T2 when the image to be printed is printed on the paper P with the front and back reversed using the above-mentioned formula (10).

[0167] Next, in step S14, the control unit 6 determines whether or not the post-reading switching arrival time T1 when the print target image is printed on the sheet P in the original orientation (without rotation) is equal to or greater than the inspection time Tk.

[0168] When it is determined that T1≥Tk (step S14: YES), in step S15, the control unit 6 determines the control content of the printing operation so as to print the print target image without rotation (in the original orientation) and discharge the paper without passing through the inversion path 44.

[0169] Here, since T1≥Tk, before the leading edge of the sheet P reaches the switching unit 51 or 53 to be controlled, the switching control of the switching unit 51 or 53 based on the inspection result of the read data of the inspection image 61 of the sheet P can be performed. That is, the time for inspecting (image inspection) the read data of the inspection image 61 can be secured.

[0170] In step S14, when it is determined that T1<Tk (step S14: NO), in step S16, the control unit 6 determines whether or not the post-reading switching arrival time T2 when the print target image is printed on the sheet P with front and back inversion is equal to or greater than the inspection time Tk.

[0171] When it is determined that T2≥Tk (step S16: YES), in step S17, the control unit 6 determines the control content of the printing operation so as to print the print target image with front and back inversion and discharge the paper without passing through the inversion path 44. The printing operation according to the control content in step S17 is the same as the printing operation in step S15 described above, except that the print target image is printed with front and back inversion.

[0172] Here, since T1 < Tk, until the leading edge of the sheet P reaches the switching unit 51 or the switching unit 53 that is the control target of the control unit 6, switching control of the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the inspection image 61 of the sheet P cannot be performed. However, since T2 ≥ Tk, by printing the print target image with front and back reversed, even if the sheet P does not pass through the reversing path 44, until the leading edge of the sheet P reaches the switching unit 51 or the switching unit 53 that is the control target, switching control of the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the inspection image 61 of the sheet P is possible. That is, by printing the print target image with front and back reversed, time for inspecting the read data of the inspection image 61 (image inspection) can be secured.

[0173] In step S16, when it is determined that T2 < Tk (step S16: NO), in step S18, the control unit 6 determines the control content of the printing operation so as to print the print target image without front and back reversal and discharge the paper by changing at least one of the conveyance path and the conveyance speed.

[0174] Here, since T1 < Tk and T2 < Tk, whether the print target image is printed in the original orientation or printed with front and back reversed, until the leading edge of the sheet P reaches the switching unit 51 or the switching unit 53, switching control of the switching unit 51 or the switching unit 53 based on the inspection result of the read data of the inspection image 61 of the sheet P cannot be performed. That is, even if the print target image is printed with front and back reversed, time for inspecting the read data of the inspection image 61 (image inspection) cannot be secured.

[0175] Therefore, in step S18, the control unit 6 controls to convey the sheet P to the switching unit 51 via the reversing path 44 in the paper discharge conveyance unit 31 as described above. Alternatively, the control unit 6 controls to convey the sheet P at a speed slower than normal in the paper discharge conveyance unit 31. Or, the control unit 6 controls to convey the sheet P to the switching unit 51 or the switching unit 53 via the reversing path 44 at a speed slower than normal in the paper discharge conveyance unit 31.

[0176] In step S18, the control unit 6 may perform control so as to print the image to be printed in a reversed state.

[0177] In step S19, the control unit 6 determines whether or not switching between the reading units 22a and 22b that read the test image 61 occurs.

[0178] For example, when the image to be printed is printed only on one side of the paper P transported by the reading and transporting unit 21, if the image to be printed is printed on the paper P with the front and back reversed, the test image 61 that should originally be printed on the front surface Pa of the paper P is printed on the back surface Pb, and the test image 61 that should originally be printed on the back surface Pb is printed on the front surface Pa. Therefore, the front surface reading unit that reads the test image 61 on the paper P transported by the reading and transporting unit 21 switches from the reading unit 22a to the reading unit 22b, or from the reading unit 22b to the reading unit 22a. That is, a switch occurs in the read surface from which the test image 61 is read.

[0179] When the reading units 22a, 22b that read the test image 61 on the paper P are switched, the distance L (specifically, the distance L31 or the distance L32) used to calculate the post-reading switching arrival times T1, T2 in equations (9) and (10) changes. In this embodiment, when the image to be printed is printed on the paper P with its front and back reversed, the reading units 22a, 22b that read the test image 61 are switched, so the control unit 6 can determine whether or not switching of the reading units 22a, 22b that read the test image 61 will occur depending on whether or not the control content of the printing operation has been determined in step S17 so that the image to be printed is printed on the paper P with its front and back reversed.

[0180] If switching between the reading units 22a and 22b that read the test image 61 occurs (step S19: YES), in step S20, the control unit 6 changes the distance L (distance L31 or distance L32) used to calculate the post-reading switch arrival times T1 and T2 in equations (9) and (10) to match the position of the reading unit 22a or reading unit 22b that reads the test image 61 after switching, and returns to step S12. If switching between the reading units 22a and 22b that read the test image 61 does not occur (step S19: NO), in step S21, the control unit 6 executes the printing operation according to the control content of step S15 or step S18 as it is.

[0181] In the printing device 1 of the third embodiment described above, when printing the image to be printed including the test image 61, if the post-reading switchover arrival time T1 when the image to be printed is printed on the paper P in its original orientation is less than the inspection time Tk, the control unit 6 determines whether it is possible to make the post-reading switchover arrival time T2 equal to or greater than the inspection time Tk by inverting the image to be printed and printing it on the paper P. Then, if it is possible to make the post-reading switchover arrival time T2 equal to or greater than the inspection time Tk by inverting the image to be printed, the control unit 6 controls the printing unit 3 to print the image to be printed on the paper P with the image to be printed inverted.

[0182] This makes it possible to reduce the occurrence of a situation in which time for image inspection cannot be secured without configuring an excessively long transport path from the reading units 22a and 22b to the switching unit 51 or the switching unit 53. Also, even if the reversing path 44 is not used as a path for buying time, it is possible to reduce the occurrence of a situation in which time for image inspection cannot be secured.

[0183] Furthermore, in the printing device 1 of this embodiment, if the post-reading switching arrival time T1 when the image to be printed is printed on the paper P in the original orientation is less than the inspection time Tk, and if the post-reading switching arrival time T2 cannot be made equal to or greater than the inspection time Tk even if the image to be printed is printed on the paper P with the front and back reversed, the control unit 6 performs the following control. That is, the control unit 6 controls the paper P to be conveyed to the switching unit 51 or the switching unit 53 via the reversing path 44 in the paper discharge conveying unit 31, or to convey the paper P by reducing the conveying speed in the paper discharge conveying unit 31, or to convey the paper P by performing both of these, thereby controlling the paper P to be conveyed, so that the post-reading switching arrival time T1 is equal to or greater than the inspection time Tk.

[0184] As a result, even if the post-reading switchover arrival time T2 cannot be made equal to or longer than the inspection time Tk even if the image to be printed is printed on the paper P with the image reversed, time can be gained on the reversing path 44 or by slowing down the conveying speed, thereby ensuring time for image inspection. As a result, it is possible to avoid stopping the conveyance of the paper P because it is not possible to ensure time for image inspection.

[0185] If the post-reading switching arrival time T1 when the image to be printed is printed on paper P in its original orientation is less than the inspection time Tk, and if the post-reading switching arrival time T2 cannot be made equal to or greater than the inspection time Tk even when the image to be printed is printed on paper P with the image reversed, the control unit 6 may perform the following control. That is, the control unit 6 may control the printing unit 3 to adjust and print the position of the test image 61 in the image to be printed, so that the post-reading switching arrival time T1 is equal to or greater than the inspection time Tk.

[0186] It is also possible to combine two or three of the following controls: control to transport paper P to switching unit 51 or switching unit 53 via inversion path 44 in the above-mentioned paper discharge transport unit 31; control to adjust the transport speed of paper P in the paper discharge transport unit 31; and control to adjust the position of the test image 61 in the image to be printed and print it.

[0187] The printing device 1 of the third embodiment can also obtain the same effects as the printing devices 1 of the first and second embodiments. That is, it is possible to reduce the occurrence of a situation in which time for image inspection cannot be secured while suppressing an increase in the size of the device and an increase in power consumption that occurs when the reversing path 44 is used as a path for buying time.

[0188] Next, a printing device 1 according to a fourth embodiment of the present invention will be described. The printing device 1 of this embodiment includes a paper feed section 2, a printing section 3, and a paper discharge section 5, which have the same structures as the printing device 1 of the second and third embodiments shown in Fig. 1 and Figs. 4(a) and (b). The printing device 1 of this embodiment differs from the control section 6 of the printing device 1 of the second and third embodiments in the configuration of the reading sections 22a and 22b of the image inspection section 4 and in part of the content of the processing performed by the control section 6.

[0189] As shown in Fig. 9, the reading unit 22a of the image inspection unit 4 of this embodiment has two reading units 221a and 222a as a plurality of types of sensors that are used depending on the contents of the inspection image 61 to be read. The reading units 221a and 222a are arranged with a shift in position in the transport direction of the paper P in the reading and transporting unit 21. The reading unit 22b, like the reading unit 22a, also has two reading units 221b and 222b as a plurality of types of sensors that are used depending on the contents of the inspection image 61 to be read. The reading units 221a and 222a are arranged with a shift in position in the transport direction of the paper P in the reading and transporting unit 21. Fig. 9 shows a case where the control target of the control unit 6 is the switching unit 51.

[0190] In each of the reading units 22a and 22b, the number of reading units serving as sensors that are used depending on the contents of the test image 61 to be read is not limited to two types as in the present embodiment, and may be three or more types.

[0191] The reading units 221a and 221b arranged on the printing unit 3 side of each of the reading units 22a and 22b are image sensors for full-surface inspection that read an image. The reading units 221a and 221b can be configured, for example, as a CIS (Contact Image Sensor). The reading units 222a and 222b arranged on the paper discharge unit 5 side of each of the reading units 22a and 22b are scanners for code inspection that read code patterns. The reading units 222a and 222b can be configured, for example, as a scanner that supports reading both one-dimensional codes and two-dimensional codes. The inspection time Tk required for the reading units 221a and 221b for full-surface inspection to inspect the read data of the inspection image 61 is longer than the inspection time Tk required for the reading units 222a and 222b for code inspection to inspect the read data of the inspection image 61.

[0192] The control unit 6 needs to finish inspecting the read data and control the switching unit 51 between the time when each reading unit 221a, 222a, 221b, 222b reads the test image 61 and the time when the leading edge (downstream end) of the paper P from which the test image 61 has been read reaches the switching unit 51 to be controlled.

[0193] 9, the time that the control unit 6 takes to perform the full surface inspection using the read data from each of the reading units 221a, 221b is proportional to the distance between each of the reading units 221a, 221b and the switching unit 51. The time that the control unit 6 takes to perform the code inspection using the read data from each of the reading units 222a, 222b is proportional to the distance between each of the reading units 222a, 222b and the switching unit 51.

[0194] In the printing device 1 of this embodiment, double-sided printing of the paper P is performed by the printing unit 3. On one of the front surface Pa and back surface Pb of the paper P, a test image 61 of an image image for full-surface inspection is printed, and on the other surface, a test image 61 of a code pattern having an area smaller than that of the image image for full-surface inspection is printed.

[0195] Therefore, by reading the test image 61 of the image image using the reading unit 221a of the upper reading unit 22a, which is far away from the switching unit 51 and therefore has a long inspection time, and reading the test image 61 of the code pattern using the reading unit 222b of the lower reading unit 22b, which is closer to the switching unit 51 and therefore has a short inspection time, it is possible to ensure a long time for inspecting the read data of the image image.

[0196] In the present embodiment, when printing the image to be printed including the test image 61 on the front surface Pa and back surface Pb of the paper P, if the test time Tk2 of the test image 61 read by the lower reading unit 22b is longer than the test time Tk1 of the test image 61 read by the upper reading unit 22a, the control unit 6 determines whether it is possible to invert the image to be printed and print it on the paper P so that the test image 61 read by the reading unit 22a has the longer test time Tk2 and the test image 61 read by the reading unit 22b has the shorter test time Tk1. If it is possible to read the test image 61 with the longer test time Tk2 by the reading unit 22a and the test image 61 with the shorter test time Tk1 by the reading unit 22b by inverting the image to be printed, the control unit 6 controls the printing unit 3 to invert the image to be printed and print it on the paper P.

[0197] The procedure of the operation performed by the printing device 1 of this embodiment is shown in the flowchart of Fig. 10. In this embodiment, the operation according to the procedure of the flowchart of Fig. 10 is started when a print job for printing the image to be printed, including the test image 61, on the front side Pa by double-sided printing is input to the printing device 1.

[0198] When a print job for printing the image to be printed including the test image 61 is input to the printing device 1, the control unit 6 starts printing the image to be printed including the test image 61 in step S31 of Fig. 10. In the next steps S32 and S33, the control unit 6 calculates inspection times Tk1 and Tk2 required to inspect the read data by the reading unit 22a (reading unit 1 in Fig. 10) and the reading unit 22b (reading unit 2 in Fig. 10), respectively, when the image to be printed is printed on the paper P in its original orientation.

[0199] The control unit 6 can calculate the inspection times Tk1, Tk2 corresponding to each of the reading units 22a, 22b based on information included in the print job indicating the content and position of the test image 61 in the image to be printed and information indicating the paper size (paper length in the transport direction). The content of the test image 61 may be information that can identify whether it is an image or a code pattern, for example. The control unit 6 may calculate the inspection times Tk1, Tk2 based on information included in the print job indicating the size of the area of ​​the test image 61 that is read by each of the reading units 22a, 22b, instead of the content of the test image 61.

[0200] In the next step S34, the control unit 6 determines whether or not the inspection time Tk1 corresponding to the reading unit 22a is longer than the inspection time Tk2 corresponding to the reading unit 22b.

[0201] If it is determined that Tk1>Tk2 (step S34: YES), in step S35, the control unit 6 determines the control content of the printing operation so that the image to be printed is printed without rotation (in the original orientation) and is discharged without passing through the reversal path 44. Specifically, the control unit 6 determines the control content so that the paper P is sequentially fed from the paper feed unit 2 to the printing unit 3, and the image to be printed, including the test image 61, is printed in the original orientation on each of the front surface Pa and back surface Pb of the paper P in the printing unit 3.

[0202] The paper sheets P printed by the printing unit 3 pass through the image inspection unit 4 and are sequentially transported to the paper discharge unit 5. In the image inspection unit 4, the reading unit 22a reads the test image 61 on the upper surface of each paper sheet P that passes sequentially, and the reading unit 22b reads the test image 61 on the lower surface of each paper sheet P to generate respective read data.

[0203] The control unit 6 inspects the read data of the inspection image 61 of each sheet P, and determines for each sheet P whether the sheet P is a normal printed matter (normal sheet). Then, the control unit 6 controls the switching unit 51 so that the normal sheets are discharged to the stacking unit 32A and the abnormal sheets are discharged to the purge discharge unit. Here, the control unit 6 sets the orientation of the switching unit 50 so that the sheet P is conveyed to the switching unit 51 along the common discharge path 41 without passing through the reverse path 44 from the introduction roller pair 45. Further, the control unit 6 sets the orientation of the switching unit 50 so that the sheet P that has reached the switching unit 53 is conveyed from the downstream discharge path 43 to the purge discharge path 52.

[0204] Here, since Tk1 > Tk2, before the leading edge of the sheet P reaches the switching unit 51 to be controlled, switching control of the switching unit 51 based on the inspection results of the read data of the inspection images 61 on the front surface Pa and the back surface Pb of the sheet P is possible. That is, it is possible to secure the time for inspecting the read data of the inspection image 61 (image inspection).

[0205] In step S34, when it is determined that Tk1 > Tk2 is not satisfied (Tk1 < Tk2) (step S34: NO), in step S36, the control unit 6 determines the following control content. That is, the control unit 6 determines the control content such that the inspection time required for inspecting the read data of the inspection image 61 read by the reading unit 22a becomes the inspection time Tk2 corresponding to the reading unit 22b calculated in step S33, and the inspection time required for inspecting the read data of the inspection image 61 read by the reading unit 22b becomes the inspection time Tk1 corresponding to the reading unit 22a calculated in step S32. Specifically, the control unit 6 determines the control content of the printing operation so that the printing target image is printed on the front surface Pa and the back surface Pb of the sheet P respectively, with the printing target image being reversed front and back and discharged without passing through the reverse path 44. The printing operation according to the control content in step S36 is the same as the printing operation in step S35 described above, except that the printing target image is printed with the front and back reversed.

[0206] In step S37 following step S35 and step S36, the control unit 6 inspects the read data of the front side Pa and back side Pb of the test image 61 of each sheet P, and judges for each sheet P whether the sheet P is a normal print (normal paper). For example, the control unit 6 analyzes the read data of the test image 61 of the front side Pa and back side Pb to obtain information indicated by the test image 61, and if the obtained information is normal for both the front side Pa and back side Pb, the control unit 6 judges that the sheet P on which the test image 61 is printed is normal paper. If the information obtained by analyzing the read data of the test image 61 is abnormal for only one of the front side Pa or back side Pb, the control unit 6 judges that the sheet P on which the test image 61 is printed is abnormal paper.

[0207] The control unit 6 controls the switching unit 51 so that normal sheets are discharged to the stacking unit 32A and abnormal sheets are discharged to the purge discharge unit. Here, the control unit 6 sets the orientation of the switching unit 50 so that the sheet P is transported from the lead-in roller pair 45 to the switching unit 51 along the common discharge path 41 without passing through the reversal path 44. The control unit 6 also sets the orientation of the switching unit 50 so that the sheet P that has reached the switching unit 53 is transported from the downstream discharge path 43 to the purge discharge path 52.

[0208] In the printer 1 of the fourth embodiment described above, the control unit 6 performs the following judgment when printing the print target image including the inspection image 61 based on an image image for full-surface inspection on one of the front surface Pa and the back surface Pb of the paper P and printing the print target image including the inspection image 61 based on a code pattern on the other surface. That is, when the inspection time Tk2 corresponding to the reading unit 22b is longer than the inspection time Tk1 corresponding to the reading unit 22a when each print target image is printed on the front surface Pa and the back surface Pb of the paper P in the original orientation, the control unit 6 judges whether or not it is possible to make the inspection time Tk1 corresponding to the reading unit 22b shorter than the inspection time Tk2 corresponding to the reading unit 22a by inverting the print target image and printing it on the paper P. Then, when it is possible to make the inspection time Tk1 corresponding to the reading unit 22b shorter than the inspection time Tk2 corresponding to the reading unit 22a by inverting the print target image, the control unit 6 controls the printing unit 3 to invert the print target image and print it on the paper P.

[0209] This makes it possible to reduce the occurrence of a situation in which the time for image inspection cannot be secured without configuring an excessively long transport path from the reading units 22a and 22b to the switching unit 51. In addition, even if the reversing path 44 is not used as a path for buying time, it is possible to reduce the occurrence of a situation in which the time for image inspection cannot be secured.

[0210] Therefore, the printing device 1 of the fourth embodiment can obtain the same effects as the printing devices 1 of the first to third embodiments. That is, it is possible to reduce the occurrence of a situation in which time for image inspection cannot be secured while suppressing an increase in the size of the device and an increase in power consumption that occurs when the reversing path 44 is used as a path for buying time.

[0211] Next, a printing device 1 according to a fifth embodiment of the present invention will be described. The printing device 1 of this embodiment includes a paper feed unit 2, a printing unit 3, an image inspection unit 4, and a paper discharge unit 5, which are the same in structure as the printing device 1 of the second and third embodiments shown in FIG. 1 and FIG. 4(a) and (b). The reading units 22a and 22b of the image inspection unit 4 of this embodiment can be configured with a scanner capable of reading both one-dimensional and two-dimensional codes, like the reading units 222a and 222b of the fourth embodiment. In the printing device 1 of this embodiment, the control unit 6 performs processing to perform operations in the same procedure as the printing device 1 of the fourth embodiment shown in FIG. 10.

[0212] In the printing device 1 of this embodiment, double-sided printing of paper P is performed in the printing unit 3. Test images 61 of a code pattern are printed on the front surface Pa and back surface Pb of the paper P. Test image 61 of a two-dimensional code that requires a relatively long inspection time is printed on one of the front surface Pa and back surface Pb, and test image 61 of a one-dimensional code that requires a relatively short inspection time is printed on the other surface.

[0213] Therefore, by reading the two-dimensional code test image 61 using the upper reading unit 22a, which is far away from the switching unit 51 and therefore has a long inspection time, and reading the one-dimensional code test image 61 using the reading unit 222b of the lower reading unit 22b, which is closer to the switching unit 51 and therefore has a short inspection time, it is possible to ensure a long time for inspecting the read data of the two-dimensional code.

[0214] The procedure of the operation performed by the printing device 1 of this embodiment is the same as the procedure performed by the printing device 1 of the fourth embodiment, and is shown in the flowchart of FIG.

[0215] In the printer 1 of the fifth embodiment described above, the control unit 6 performs the following judgment when printing a print target image including a two-dimensional code inspection image 61 on one of the front surface Pa and the back surface Pb of the paper P and printing a print target image including a one-dimensional code inspection image 61 on the other surface. That is, when the inspection time Tk2 corresponding to the reading unit 22b is longer than the inspection time Tk1 corresponding to the reading unit 22a when each print target image is printed on the front surface Pa and the back surface Pb of the paper P in the original orientation, the control unit 6 judges whether or not it is possible to make the inspection time Tk1 corresponding to the reading unit 22b shorter than the inspection time Tk2 corresponding to the reading unit 22a by inverting the print target image and printing it on the paper P. Then, when it is possible to make the inspection time Tk1 corresponding to the reading unit 22b shorter than the inspection time Tk2 corresponding to the reading unit 22a by inverting the print target image, the control unit 6 controls the printing unit 3 to invert the print target image and print it on the paper P.

[0216] The printing device 1 of the fifth embodiment can also achieve the same effects as the printing device 1 of the fourth embodiment.

[0217] In the above embodiment, the case where the reversing path 44 is used as the path for buying time has been described, but the path for buying time may not involve the reversing of the paper P. It is sufficient that the path for buying time is changed in part of the path of the paper P from the reading unit to the switching unit, and that the post-reading switching arrival time is controlled to be equal to or longer than the inspection time.

[0218] In the above embodiment, the image to be printed is rotated 180° from its original orientation, but this is not limited to this. For example, the rotation angle may be 90°. When the image to be printed is rotated 90°, the orientation of the paper P may also be rotated 90°.

[0219] In a multi-page print job, if there is a page that satisfies the condition that the post-reading switching arrival times T1, T2 of the test image 61 of the image to be printed are less than the test time Tk, the image to be printed may be rotated from the original orientation and printed only for that page. Alternatively, in addition to the page that has the test image 61 that satisfies the condition, the image to be printed may also be rotated from the original orientation and printed for pages that do not have the test image 61 that satisfies the condition.

[0220] In the latter case, for example, if all pages of a print job are rotated from their original orientation and printed, there is no need to separate the paper P feed source or paper discharge destination according to the print orientation, and the time required to feed or discharge the paper P can be reduced, thereby improving the speed of the print process.

[0221] In the above-described embodiment, the printing device 1 has been described as having two stacking units, 32A and 32B, but the printing device 1 may have three or more stacking units. It is sufficient that the destination of the paper P is switched between multiple stacking units based on the inspection result of the read data of the test image 61.

[0222] In the above-described embodiment, the control unit 6 is described as inspecting the read data of the test image 61, but the inspection of the read data of the test image 61 may also be performed by an external device, and the control unit 6 may acquire the inspection results.

[0223] The present invention is not limited to the above-described embodiment, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment.

[0224] [Note] This application discloses the following inventions.

[0225] (Appendix 1) a printing unit that prints a print target image including a test image on a printing medium; a plurality of stacking units on which the print media printed by the printing unit are stacked; a transport unit having a switching unit that switches a transport destination of the print medium among the plurality of stacking units, and transports the print medium printed by the printing unit to one of the plurality of stacking units; a reading unit that is disposed between the printing unit and the switching unit in a conveying direction of the print medium by the conveying unit and that reads the test image on the print medium conveyed by the conveying unit; a control unit that controls the switching unit to switch the destination of the print medium among the plurality of stacking units based on an inspection result of read data generated by the reading unit reading the test image, A printing device characterized in that, when the image to be printed is printed on the printing medium in its original orientation, the control unit controls the printing unit so that the post-reading switching arrival time, which is the time from when the reading unit reads the test image on the printing medium to when the leading edge of the printing medium reaches the switching unit, is less than the inspection time, which is the time required from when the reading unit reads the test image to when it controls the switching unit based on the inspection result.

[0226] (Appendix 2) The control unit is When a change in a destination of the print medium occurs based on a print job of the image to be printed, the post-reading switch arrival time is changed according to the change in the destination of the print medium; The printing device described in Appendix 1 is characterized in that, when the post-reading switching arrival time is less than the inspection time and it is possible to make the post-reading switching arrival time equal to or greater than the inspection time by rotating the image to be printed from its original orientation and printing it on a printing medium, the printing unit is controlled to rotate the image to be printed from its original orientation and print it on a printing medium so that the post-reading switching arrival time is equal to or greater than the inspection time.

[0227] (Appendix 3) the reading unit includes a front-side reading unit and a back-side reading unit that read the test image on the front side of the print medium and the test image on the back side of the print medium at different positions in the transport direction, The control unit is When a change in a reading target surface for reading the test image of the print medium occurs based on a print job of the print target image, the post-reading switch arrival time is changed according to the change in the reading target surface; The printing device described in Appendix 1 or Appendix 2, characterized in that when the post-reading switching arrival time is less than the inspection time and it is possible to make the post-reading switching arrival time equal to or greater than the inspection time by rotating the image to be printed from its original orientation and printing it on a printing medium, the printing unit is controlled to rotate the image to be printed from its original orientation and print it on a printing medium so that the post-reading switching arrival time is equal to or greater than the inspection time.

[0228] (Appendix 4) a printing unit that prints a print target image including a test image on a printing medium; a plurality of stacking units on which the print media printed by the printing unit are stacked; a transport unit having a switching unit that switches a transport destination of the print medium among the plurality of stacking units, and transports the print medium printed by the printing unit to one of the plurality of stacking units; a reading unit that is disposed between the printing unit and the switching unit in a conveying direction of the print medium by the conveying unit and that reads the test image on the print medium conveyed by the conveying unit; a control unit that controls the switching unit to switch the destination of the print medium among the plurality of stacking units based on an inspection result of read data generated by the reading unit reading the test image, The control unit is when the image to be printed is printed on the printing medium in its original orientation, a post-reading switching arrival time, which is the time from when the reading unit reads the test image on the printing medium to when the leading edge of the printing medium reaches the switching unit, is less than an inspection time, which is the time from when the reading unit reads the test image to when the reading unit controls the switching unit based on the inspection result; A printing device characterized by controlling the printing unit to rotate the image to be printed from its original orientation and print it on the printing medium so that the post-reading switching arrival time is equal to or longer than the inspection time, when it is possible to make the post-reading switching arrival time equal to or longer than the inspection time by rotating the image to be printed from its original orientation and printing it on the printing medium.

[0229] (Appendix 5) The control unit is If the post-reading switching arrival time when the image to be printed is printed on a printing medium in its original orientation is less than the inspection time, and if the image to be printed is rotated from its original orientation and printed on a printing medium, the post-reading switching arrival time cannot be made to be equal to or greater than the inspection time, A printing device as described in any one of Supplementary Notes 2 to 4, characterized in that the post-reading switching arrival time is controlled to be equal to or longer than the inspection time by at least one of the following controls: control for changing a part of the path along which the printing medium is transported in the transport section; control for adjusting the transport speed of the printing medium in the transport section; and control for adjusting and printing the position of the test image within the image to be printed.

[0230] (Appendix 6) The printing device described in Appendix 5, characterized in that the control unit determines the inspection time based on the size of the area for reading the inspection image of the printing medium obtained from the print job of the image to be printed.

[0231] (Appendix 7) The printing device described in Appendix 5, characterized in that the control unit specifies the inspection time based on the contents of the inspection image obtained from the print job of the image to be printed. [Explanation of symbols]

[0232] 1 Printing device 2 Paper feed section 3 Printing Department 4. Imaging Inspection Department 5. Paper output section 6. Control Unit 21 Reading and conveying section 22, 22a, 22b, 221a, 221b, 222a, 222b Reading unit 31 Paper ejection transport section 32A, 32B Loading section 41 Common paper exit path 42 Upstream paper ejection path 43 Downstream paper ejection path 44 Reversal Route 45 Introduction Roller Pair 46 Rising Roller Pair 47 Upstream paper discharge conveying roller pair 48 downstream discharge conveying roller pair 49 Reversing roller pair 50, 51, 53 Switching section 52 Purge paper ejection path 61 Test Images P paper Pa Paper surface Pb paper back

Claims

1. a printing unit that prints a print target image including a test image on a printing medium; a plurality of stacking units on which the print media printed by the printing unit are stacked; a transport unit having a switching unit that switches a transport destination of the print medium among the plurality of stacking units, and transports the print medium printed by the printing unit to one of the plurality of stacking units; a reading unit that is disposed between the printing unit and the switching unit in a conveying direction of the print medium by the conveying unit and that reads the test image on the print medium conveyed by the conveying unit; a control unit that controls the switching unit to switch the destination of the print medium among the plurality of stacking units based on an inspection result of read data generated by the reading unit reading the test image, The control unit controls the printing unit to change the content of the print job for the image to be printed so that the post-reading switching arrival time, which is the time from when the reading unit reads the test image on the printing medium to when the leading edge of the printing medium reaches the switching unit, is less than the inspection time, which is the time from when the reading unit reads the test image to when the reading unit controls the switching unit based on the inspection result, when the image to be printed is printed on the printing medium in its original orientation.

2. A printing unit that prints a print target image including a test image on a printing medium; a plurality of stacking units on which the print media printed by the printing unit are stacked; a transport unit having a switching unit that switches a transport destination of the print medium among the plurality of stacking units, and transports the print medium printed by the printing unit to one of the plurality of stacking units; a reading unit that is disposed between the printing unit and the switching unit in a conveying direction of the print medium by the conveying unit and that reads the test image on the print medium conveyed by the conveying unit; a control unit that controls the switching unit to switch the destination of the print medium among the plurality of stacking units based on an inspection result of read data generated by the reading unit reading the test image, The control unit is when the image to be printed is printed on the printing medium in its original orientation, if a post-reading switching arrival time, which is the time from when the reading unit reads the test image on the printing medium until the leading edge of the printing medium reaches the switching unit, is less than an inspection time, which is the time from when the reading unit reads the test image until it controls the switching unit based on the inspection result, controlling the printing unit so that the post-reading switching arrival time is equal to or greater than the inspection time; When a change in a destination of the print medium occurs based on a print job of the image to be printed, the post-reading switch arrival time is changed according to the change in the destination of the print medium; A printing device characterized in that, when the post-reading switching arrival time is less than the inspection time and it is possible to make the post-reading switching arrival time equal to or greater than the inspection time by rotating the image to be printed from its original orientation and printing it on a printing medium, the printing unit is controlled to rotate the image to be printed from its original orientation and print it on a printing medium so that the post-reading switching arrival time is equal to or greater than the inspection time.

3. A printing unit that prints a print target image including a test image on a printing medium; a plurality of stacking units on which the print media printed by the printing unit are stacked; a transport unit having a switching unit that switches a transport destination of the print medium among the plurality of stacking units, and transports the print medium printed by the printing unit to one of the plurality of stacking units; a reading unit that is disposed between the printing unit and the switching unit in a conveying direction of the print medium by the conveying unit and that reads the test image on the print medium conveyed by the conveying unit; a control unit that controls the switching unit to switch the destination of the print medium among the plurality of stacking units based on an inspection result of read data generated by the reading unit reading the test image, the reading unit includes a front-side reading unit and a back-side reading unit that read the test image on the front side of the print medium and the test image on the back side of the print medium at different positions in the transport direction, The control unit is when the image to be printed is printed on the printing medium in its original orientation, if a post-reading switching arrival time, which is the time from when the reading unit reads the test image on the printing medium until the leading edge of the printing medium reaches the switching unit, is less than an inspection time, which is the time from when the reading unit reads the test image until it controls the switching unit based on the inspection result, controlling the printing unit so that the post-reading switching arrival time is equal to or greater than the inspection time; When a change in a reading target surface for reading the test image of the print medium occurs based on a print job of the print target image, the post-reading switch arrival time is changed according to the change in the reading target surface; A printing device characterized in that, when the post-reading switching arrival time is less than the inspection time and it is possible to make the post-reading switching arrival time equal to or greater than the inspection time by rotating the image to be printed from its original orientation and printing it on a printing medium, the printing unit is controlled to rotate the image to be printed from its original orientation and print it on a printing medium so that the post-reading switching arrival time is equal to or greater than the inspection time.

4. a printing unit that prints a print target image including a test image on a printing medium; a plurality of stacking units on which the print media printed by the printing unit are stacked; a transport unit having a switching unit that switches a transport destination of the print medium among the plurality of stacking units, and transports the print medium printed by the printing unit to one of the plurality of stacking units; a reading unit that is disposed between the printing unit and the switching unit in a conveying direction of the print medium by the conveying unit and that reads the test image on the print medium conveyed by the conveying unit; a control unit that controls the switching unit to switch the destination of the print medium among the plurality of stacking units based on an inspection result of read data generated by the reading unit reading the test image, The control unit is when the image to be printed is printed on the printing medium in its original orientation, a post-reading switching arrival time, which is the time from when the reading unit reads the test image on the printing medium to when the leading edge of the printing medium reaches the switching unit, is less than an inspection time, which is the time from when the reading unit reads the test image to when the reading unit controls the switching unit based on the inspection result; A printing device characterized by controlling the printing unit to rotate the image to be printed from its original orientation and print it on the printing medium so that the post-reading switching arrival time is equal to or longer than the inspection time, when it is possible to make the post-reading switching arrival time equal to or longer than the inspection time by rotating the image to be printed from its original orientation and printing it on the printing medium.

5. The control unit is If the post-reading switching arrival time when the image to be printed is printed on a printing medium in its original orientation is less than the inspection time, and if the image to be printed is rotated from its original orientation and printed on a printing medium, the post-reading switching arrival time cannot be made to be equal to or greater than the inspection time, A printing device as described in any one of claims 2 to 4, characterized in that the post-reading switching arrival time is controlled to be equal to or longer than the inspection time by at least one of the following controls: control to change a portion of the path along which the printing medium is transported in the transport section; control to adjust the transport speed of the printing medium in the transport section; and control to adjust and print the position of the test image in the image to be printed.

6. A printing unit that prints a print target image including a test image on a printing medium; a plurality of stacking units on which the print media printed by the printing unit are stacked; a transport unit having a switching unit that switches a transport destination of the print medium among the plurality of stacking units, and transports the print medium printed by the printing unit to one of the plurality of stacking units; a reading unit that is disposed between the printing unit and the switching unit in a conveying direction of the print medium by the conveying unit and that reads the test image on the print medium conveyed by the conveying unit; a control unit that controls the switching unit to switch the destination of the print medium among the plurality of stacking units based on an inspection result of read data generated by the reading unit reading the test image, the reading unit includes a front-side reading unit and a back-side reading unit that read the test image on the front side of the print medium and the test image on the back side of the print medium at different positions in the transport direction, when a post-reading switching arrival time, which is a time from when the reading unit reads the test image on the print medium until the leading edge of the print medium reaches the switching unit when the image to be printed is printed on the print medium in its original orientation, is less than an inspection time, which is a time from when the reading unit reads the test image until the switching unit is controlled based on the inspection result, the control unit controls the printing unit so that the post-reading switching arrival time is equal to or greater than the inspection time; A printing device characterized in that, when the test image is present on only one side of the printing medium, the control unit controls the printing unit to print the image to be printed on the side opposite to the original side of the printing medium if the post-reading switching arrival time is less than the inspection time and it is possible to make the post-reading switching arrival time greater than or equal to the inspection time by printing the image to be printed on the side opposite to the original side of the printing medium.

7. A printing unit that prints a print target image including a test image on a printing medium; a plurality of stacking units on which the print media printed by the printing unit are stacked; a transport unit having a switching unit that switches a transport destination of the print medium among the plurality of stacking units, and transports the print medium printed by the printing unit to one of the plurality of stacking units; a reading unit that is disposed between the printing unit and the switching unit in a conveying direction of the print medium by the conveying unit and that reads the test image on the print medium conveyed by the conveying unit; a control unit that controls the switching unit to switch the destination of the print medium among the plurality of stacking units based on an inspection result of read data generated by the reading unit reading the test image, the reading unit includes a front-side reading unit and a back-side reading unit that read the test image on the front side of the print medium and the test image on the back side of the print medium at different positions in the transport direction, the front side reading unit and the back side reading unit each have a plurality of types of sensors that are used depending on the content of the test image to be read, when a post-reading switching arrival time, which is a time from when the reading unit reads the test image on the print medium until the leading edge of the print medium reaches the switching unit when the image to be printed is printed on the print medium in its original orientation, is less than an inspection time, which is a time from when the reading unit reads the test image until the switching unit is controlled based on the inspection result, the control unit controls the printing unit so that the post-reading switching arrival time is equal to or greater than the inspection time; A printing device characterized in that, when the test images, each of which has a different type of sensor used for reading, are present on each side of the printing medium, the control unit controls the printing unit to print the image to be printed on the side opposite to the original side of the printing medium if the post-reading switching arrival time on at least one side of the printing medium is less than the inspection time and it is possible to make the post-reading switching arrival time greater than or equal to the inspection time on both sides of the printing medium by printing the image to be printed on the side opposite to the original side of the printing medium.

Images