JP7655741B2 - Printing device - Google Patents

Description

The present invention relates to a printing device.

Printing devices are known that print on print media and inspect the printed image.

There is also a known discharge device that switches the destination of the print medium among multiple discharge sections based on the results of inspection of the image printed on the print medium (see Patent Document 1).

Japanese Patent Application Publication No. 11-263001

However, 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.

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

In response to this, if an existing path, such as a path for flipping the print medium that is 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 transport of the print medium 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 device from becoming larger.

However, in this case, it is necessary to drive rollers to transport the print medium along the time-wasting path, which results in increased power consumption.

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 in which time cannot be secured for image inspection to switch the destination of the print media, while suppressing increases in the size of the device and power consumption.

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 media 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-reading unit that reads the test image on the printing medium transported by the transport unit based on the 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 print medium between the multiple stacking units, and when a post-reading switching arrival time, which is the 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 the time from when the reading unit reads the test image until the reading unit 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.

According to another aspect of the present invention, the apparatus 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 media printed by the printing unit are respectively stacked, and a transport unit that has a switching unit that switches the destination of the printing media between the plurality of stacking units and transports the printing media 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 media between the plurality of stacking units based on the inspection results of the read data generated by the reading unit reading the test image, The control unit controls the printing unit to rotate the image to be printed from its original orientation and print it on the print medium so that the post-reading switching arrival time is equal to or greater than the inspection time when the post-reading switching arrival time, which is the 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, is less than the inspection time, which is the time from when the reading unit reads the test image until the switching unit controls the switching unit based on the inspection result, and the post-reading switching arrival time can be set to equal to or greater than the inspection time by rotating the image to be printed from its original orientation and printing it on the print medium.

The printing device of the present invention can reduce the occurrence of situations where time cannot be secured for image inspection in order to switch the destination of the print medium, while suppressing the increase in size of the device and the increase in power consumption.

1 is a schematic configuration diagram of a printing device according to a first embodiment. 10 is a flowchart for explaining the operation of the printing device when printing an image to be printed, including an image for inspection. 11 is a diagram for explaining a method for calculating a post-reading switching arrival time. 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. 4 is an explanatory diagram showing the positional relationship between two reading units of the image inspection unit and two switching units of the paper discharge unit. FIG. 13 is a flowchart for explaining the operation of the printing device when the printing device according to the second and third embodiments prints a print target image including a test image. 11 is a diagram for explaining a method for calculating a post-reading switching arrival time. FIG. 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. 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. 10 is a flowchart for explaining the operation of the printing device when printing an image to be printed, including an image for inspection. 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.

The following describes an embodiment of the present invention with reference to the drawings. The same or equivalent parts and components are denoted by the same or equivalent reference numerals throughout the drawings.

The embodiments shown below are examples of devices that embody the technical ideas of this invention, and the technical ideas of this invention do not specify the materials, shapes, structures, arrangements, etc. of each component part as described below. The technical ideas of this invention can be modified in various ways within the scope of the claims.

Figure 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 paper surface in Figure 1 are defined as the top, bottom, left, and right directions.

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

The paper feed unit 2 has multiple paper feed trays 11 on which paper (corresponding to print media) P is stacked, and the paper P is fed from the paper feed trays 11 to the printing unit 3.

The printing unit 3 prints on the paper P fed from the paper feed unit 2. The printing unit 3 includes multiple inkjet heads 16, a circulating transport unit 17, and a connecting transport unit 18.

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

The circulating transport unit 17 transports the paper P fed from the paper feed unit 2. The circulating transport unit 17 has an inversion unit 19 for inverting the paper P.

When printing on one side of the paper with face-up ejection, the circulating transport unit 17 transports the paper P printed on one side by the inkjet head 16 directly to the connecting transport unit 18.

During double-sided printing, the circulating transport unit 17 transports the paper P, which has been printed on its front side by the inkjet head 16, to the inverting unit 19, where it is inverted and re-fed to the inkjet head 16. The circulating transport unit 17 then transports the paper P, which has been printed on its back side by the inkjet head 16, to the connecting transport unit 18. During face-down discharge, the circulating transport unit 17 transports the paper P, which has been printed on its front side by the inkjet head 16, to the inverting unit 19, where it is inverted and re-fed to the inkjet head 16. The circulating transport unit 17 then transports the printed ... passed through the inkjet head 16 without being printed on its back side, to the connecting transport unit 18.

The communication transport unit 18 transports the printed paper P from the circulating transport unit 17 to the image inspection unit 4.

The image inspection unit 4 reads the 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.

The reading and conveying unit 21 conveys the paper P conveyed by the communication conveying unit 18 to the paper discharge unit 5.

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 composed of 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.

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

When the paper P transported by the reading and transporting unit 21 is double-sided printing or single-sided printing 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 side and the front surface Pa is placed on the lower 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).

The paper discharge unit 5 discharges (ejects) the paper P printed by the printing unit 3. The paper discharge unit 5 includes a paper discharge transport unit 31 and stacking units 32A and 32B.

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 together constitute a conveying unit that conveys the paper P printed by the printing unit 3 to either the stacking units 32A or 32B.

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, a lead-in roller pair 45, a lift roller pair 46, an upstream discharge conveying roller pair 47, a plurality of downstream discharge conveying roller pairs 48, a reversing roller pair 49, and switching sections 50 and 51.

The common discharge path 41 is a transport path common to paper P transported to stacking section 32A and paper P transported to stacking section 32B.

The upstream discharge path 42 is connected to the downstream end of the common discharge path 41 in the transport direction of the paper P, and is a transport path for transporting and discharging the paper P to the stacking section 32A.

The downstream discharge path 43 is connected to the downstream end of the common discharge path 41 and is a transport path for transporting and discharging the paper P to the stacking section 32B.

The inversion path 44 is a transport path for switching back the paper P and inverting it. The inversion path 44 is connected to the common discharge path 41. The inversion 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 downstream of this branch point near the upstream side of the lift roller pair 46.

The lead-in roller pair 45 leads the paper P transported by the reading transport 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.

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.

The upstream discharge conveying roller pair 47 conveys the paper P conveyed by the lift roller pair 46 to the stacking section 32A and discharges it. The upstream discharge conveying roller pair 47 is disposed at the downstream end of the upstream discharge path 42.

The downstream discharge conveying roller pair 48 conveys the paper P conveyed by the lifting roller pair 46 to the stacking section 32B and discharges it. The downstream discharge conveying roller pair 48 is arranged along the downstream discharge path 43.

The pair of reversing rollers 49 switches back the paper P conveyed by the pair of lead-in rollers 45 and conveys it to the pair of lifting rollers 46. The pair of reversing rollers 49 is arranged along the reversing path 44.

The switching unit 50 switches the transport path of the paper P between the common discharge path 41 and the inversion path 44 near the downstream side of the lead-in roller pair 45.

The switching unit 51 switches the transport path of the paper P downstream 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 stacking units 32A and 32B.

The stacking sections 32A and 32B are used to stack 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.

The control unit 6 controls the operation of each part of the printing device 1. The control unit 6 is configured with a CPU, RAM, ROM, hard disk, etc.

When the image to be printed, including the test image 61, is printed on the paper P, the control unit 6 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.

In addition, when printing the image to be printed including the test image 61, if the post-reading switchover arrival time described below when the image to be printed is printed on the paper P in its original orientation is less than the test time Tk described below, and if it is possible to make the post-reading switchover arrival time equal to or greater than the test 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 switchover arrival time is equal to or greater than the test time Tk.

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.

The post-reading switching arrival time described above 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 when the paper P does not pass through the inversion path 44. When 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 switching back.

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 results of the read data of the inspection image 61. The inspection time Tk includes the time required to inspect the read data of the inspection image 61 (image inspection). The inspection time Tk is a fixed time that is known in advance by the control unit 6.

The test image 61 consists of a barcode, etc. The test image 61 includes test information, such as information indicating the page order.

Next, we will explain the operation of the printing device 1 when printing the image to be printed, including the test image 61.

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

In step S1 of FIG. 2, 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 is equal to or greater than the inspection time Tk.

Here, the post-read switching arrival time T1 is expressed by the following formula (1).

T1=L1/V...(1)
Here, V is the transport speed of the paper P on 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.

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 units 22a and 22b finish reading the test image 61 when the image to be printed is printed on the paper P in the original orientation (without rotation). Note that in FIG. 3, the parts of the image to be printed other than the test image 61 are not shown.

Distance L1 is expressed by the following formula (2):

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.

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 its original orientation (not rotated).

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

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 eject the paper without passing through the inversion path 44.

Specifically, the control unit 6 sequentially feeds paper P 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.

The paper P printed by the printing unit 3 passes through the image inspection unit 4 and is transported sequentially to the paper discharge unit 5. In the image inspection unit 4, the reading unit 22a reads the test image 61 on the top surface of each paper P that passes sequentially, and the reading unit 22b reads the test image 61 on the bottom surface of each paper P to generate respective read data.

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

The control unit 6 then controls the switching unit 51 so that normal paper is discharged to the stacking unit 32A and abnormal paper is discharged to the stacking unit 32B. Here, the control unit 6 sets the orientation of the switching unit 50 so that the paper P is transported from the lead-in roller pair 45 to the switching unit 51 along the common paper discharge path 41 without passing through the reversing path 44.

Here, because T1≧Tk, it is possible to control the switching of the switching unit 51 based on the inspection results of the read data of the test image 61 of the paper P before the leading edge of the paper P reaches the switching unit 51. In other words, it is possible to secure time for inspecting the read data of the test image 61 (image inspection).

When the test image 61 is printed on both sides of the paper P, it is printed so that the distance Lt1 on the front side Pa is equal to the distance Lt1 on the back side Pb. Therefore, the test image 61 on the front side Pa and the test image 61 on the back side Pb are read by the corresponding reading units 22b, 22a at the same time. If the inspection result of at least one of the read data of the test image 61 on the front side Pa and the test image 61 on the back side Pb of the paper P is abnormal, the paper P is determined to be abnormal paper.

When the number of sheets of paper P required for the print job has been printed by the printing unit 3 and ejected by the paper ejection unit 5, the series of operations is completed.

If it is determined in step S1 that T1<Tk (step S1: NO), in step S3, the control unit 6 determines whether the post-reading switchover arrival time T2 when the image to be printed is rotated 180° from the original orientation and printed on the paper P is equal to or greater than the inspection time Tk.

Here, the post-read switching arrival time T2 is expressed by the following formula (3).

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).

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

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

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

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.

Here, because T1<Tk, it is not possible to perform switching control of the switching unit 51 based on the inspection results of the read data of the test image 61 of the paper P before the leading edge of the paper P reaches the switching unit 51. However, because T2≧Tk, by rotating the image to be printed 180° from its original orientation and printing it, it is possible to perform switching control of the switching unit 51 based on the inspection results of the read data of the test image 61 of the paper P before the leading edge of the paper P reaches the switching unit 51, even if the paper P does not go through the inversion path 44. In other words, by rotating the image to be printed 180° from its original orientation and printing it, it is possible to ensure time for inspection of the read data of the test image 61 (image inspection).

If it is determined in step S3 that T2<Tk (step S3: NO), in step S5, the control unit 6 executes a printing operation to print the image to be printed without rotation and eject the paper via the inversion path 44.

In the printing operation of step S5, the control unit 6 sets the orientation of the switching unit 50 so that the paper P is guided from the lead-in roller pair 45 to the inversion path 44. As a result, the paper P is transported to the switching unit 51 via the inversion path 44 in the paper discharge transport unit 31.

Here, since T1<Tk and T2<Tk, even if the image to be printed is printed in the original orientation or rotated 180° from the original orientation, if the paper P does not pass through the inversion path 44, it is not possible to perform switching control of the switching unit 51 based on the inspection results of the read data of the test image 61 of the paper P before the leading edge of the paper P reaches the switching unit 51. In other words, even if the image to be printed is printed rotated 180° from the original orientation, if the paper P does not pass through the inversion path 44, it is not possible to secure time for inspection of the read data of the test image 61 (image inspection).

When the paper P passes through the inversion path 44, the distance that the paper P is transported is 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 switchover arrival time is longer than the inspection time Tk, regardless of the position of the test image 61 on the paper P.

Therefore, in the printing operation of step S5, the control unit 6 controls the discharge transport unit 31 to transport the paper P to the switching unit 51 via the reversing path 44 as described above. In other words, the existing reversing path 44 is used as a path to buy 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 results of the read data of the inspection image 61 of the paper P.

Note that in the printing operation of step S5, the image to be printed may be rotated 180° from its original orientation before being printed.

As described above, in the printing device 1, when printing the image to be printed including the test image 61, if the post-reading switchover arrival time when the image to be printed is printed on the paper P in its original orientation is less than the test time Tk, and if it is possible to make the post-reading switchover arrival time equal to or greater than the test 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 switchover arrival time is equal to or greater than the test time Tk.

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

In addition, in the printing device 1, if the post-reading switchover 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 if the post-reading switchover 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 the paper P, the control unit 6 controls the paper discharge transport unit 31 to transport the paper P to the switching unit 51 via the inversion path 44, thereby controlling the post-reading switchover arrival time to be equal to or greater than the inspection time Tk.

As a result, even if the image to be printed is rotated 180 degrees from its original orientation and printed on the paper P, and the post-reading switchover arrival time cannot be made equal to or longer than the inspection time Tk, time can be gained on the reversal path 44, ensuring time for image inspection. As a result, it is possible to avoid stopping the transport of the paper P due to an inability to ensure time for image inspection.

In the case where the post-reading switchover 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 switchover 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 switchover 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 conveying section 31 to be adjusted. In this case, the paper P may or may not pass through the inversion path 44 in the paper discharge conveying section 31.

In addition, if the post-reading switchover time is less than the inspection time Tk when the image to be printed is printed on paper P in its original orientation, and if the post-reading switchover 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 post-reading switchover time may be made equal to or greater than the inspection time Tk by controlling the printing unit 3 to adjust and print the position of the inspection image 61 within the image to be printed.

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 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 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 it is not possible to make the post-reading switching arrival time 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.

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 conveying unit 31, control of adjusting the conveying speed of the paper P in the paper discharge conveying unit 31, and control of adjusting and printing the position of the test image 61 in the image to be printed may be combined. In other words, if the post-reading switch 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 the post-reading switch 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 its original orientation and printed on the paper P, the post-reading switch arrival time may be controlled to be equal to or greater 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 conveying unit 31, control of adjusting the conveying speed of the paper P in the paper discharge conveying unit 31, and control of adjusting and printing the position of the test image 61 in the image to be printed.

Next, a printing device 1 according to a second embodiment of the present invention will be described. As shown in Figs. 4(a) and (b), the printing device 1 according to this embodiment has a different configuration of the image inspection unit 4 and the paper discharge unit 5 from the printing device 1 according to the first embodiment shown in Fig. 1.

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 in 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 in 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.

The discharge transport section 31 of the discharge section 5 shown in FIG. 4(b) further includes a purge discharge path 52 and a switching section 53. The purge discharge path 52 branches off from the downstream discharge path 43 and extends above the discharge section 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 section 5 for discharge.

The switching unit 53 switches the transport path of the paper P between the further downstream discharge path 43 continuing to the stacking unit 32B and the purge discharge path 52 midway along the downstream discharge path 43.

The paper P printed by the printing unit 3 passes through the image inspection unit 4 and is transported sequentially to the paper discharge unit 5. In the image inspection unit 4, the reading unit 22a reads the test image 61 on the top surface of each paper P that passes sequentially, and the reading unit 22b reads the test image 61 on the bottom surface of each paper P to generate respective read data.

The control unit 6 inspects the read data of the test image 61 of each sheet P, and determines 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 reading units 22a and 22b that read the test image 61, and obtains the information indicated by the test image 61.

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

If the test image 61 is read by both reading units 22a and 22b, and the information acquired by both reading units 22a and 22b is normal, the paper P on which the test image 61 is printed is determined to be 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.

The control unit 6 then controls the switching unit 51 or the switching unit 53 so that normal paper is discharged to the stacking unit 32A or the stacking unit 32B, and abnormal paper is 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, for example, normal paper is discharged to the stacking unit 32A until the number of discharged sheets reaches a specified number, and normal paper after the number of discharged sheets exceeds the specified number is discharged to the stacking unit 32B.

The specified number can be, for example, the maximum number of sheets that can be loaded in the stacking section 32A (e.g., 4,000 sheets). The specified number can also be, for example, the number of sheets to be discharged from the stacking section 32A specified by the user. The number of sheets to be discharged can be specified 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 discharge path 41 without passing through the reversal path 44.

In this embodiment, the printed paper P that has finished printing in the printing unit 3 in FIG. 1 is transported to the common paper discharge path 41 of the paper discharge unit 5 via the reading and transport unit 21 of the image inspection unit 4. If the paper P does not need to be turned over, the switching unit 50 transports the paper P from the common paper discharge path 41 to the upstream paper discharge path 42 via the shortest route that does not pass through the reversal path 44, and then transports the paper P to the switching unit 51.

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

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

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 that does not pass through the reversal 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.

When the paper P transported from the printing unit 3 to the switching unit 51 or the switching unit 53 via the shortest route is one that has been printed on one side with face-up paper 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.

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

When the image to be printed, including the test image 61, is printed on the paper P, the control unit 6 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.

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 test 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 test 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 switchover arrival time T2 equal to or greater than the test 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 switchover arrival time T2 is equal to or greater than the test time Tk.

The 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 or the switching unit 53 based on the inspection results of the read data of the inspection image 61.

Next, the operation of the printing device 1 when printing an image to be printed that includes 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 that includes 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 that includes the test image 61 in the printing device 1 according to the third embodiment described below. 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 begins when a print job for printing an image to be printed that includes the test image 61 is input to the printing device 1.

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 S11 of FIG. 6. In the next step S12, the control unit 6 calculates the post-reading switchover arrival time (transport time) T1 when the image to be printed is printed on the paper P in the original orientation.

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

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.

As shown in FIG. 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 the original orientation (without rotation).

Distance L21 is expressed by the following formula (6).

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 the switching unit 53 that is controlled by the control unit 6, without passing through the reversal 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).

The control unit 6 calculates the distance Lt1 based on information contained in the print job indicating the position of the test image 61 in the image to be printed and information indicating the paper size (paper length in the transport direction).

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.

In the next step S13, the control unit 6 calculates the post-reading switchover arrival time (transport time) T2 when the image to be printed is rotated 180° from the original orientation and printed on the paper P.

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

T2=L22/V...(7)
As shown in Figure 7, L22 is the distance between the tip (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.

Distance L22 is expressed by the following formula (8).

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

The control unit 6 calculates the distance Lt2 based on information contained in the print job indicating the position of the test image 61 in the image to be printed and information indicating the paper size (paper length in the transport direction).

Next, in step S14, the control unit 6 determines whether the post-reading switching 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.

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 its original orientation) and is discharged without passing through the inversion 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 its original orientation in the printing unit 3.

The paper P printed by the printing unit 3 passes through the image inspection unit 4 and is transported sequentially to the paper discharge unit 5. In the image inspection unit 4, the reading unit 22a reads the test image 61 on the top surface of each paper P that passes sequentially, and the reading unit 22b reads the test image 61 on the bottom surface of each paper P to generate respective read data.

The control unit 6 inspects the scan data of the test image 61 of each sheet P, and determines for each sheet P whether the sheet P is a normal print (normal sheet). The control unit 6 then 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.

Here, because T1≧Tk, it is possible to control switching of switching unit 51 or switching unit 53 based on the inspection results of the read data of test image 61 of paper P before the leading edge of paper P reaches switching unit 51 or switching unit 53 to be controlled. In other words, it is possible to secure time for inspection of the read data of test image 61 (image inspection).

When the test image 61 is printed on both sides of the paper P, it is printed so that the distance Lt1 on the front side Pa is equal to the distance Lt1 on the back side Pb. Therefore, the test image 61 on the front side Pa and the test image 61 on the back side Pb are read by the corresponding reading units 22b, 22a at different times. If the inspection result of at least one of the read data of the test image 61 on the front side Pa and the test image 61 on the back side Pb of the paper P is abnormal, the paper P is determined to be abnormal paper.

If it is determined in step S14 that T1<Tk (step S14: NO), in step S16, the control unit 6 determines whether the post-reading switchover arrival time T2 when the image to be printed is rotated 180° from the original orientation and printed on the paper P is equal to or greater than the inspection time Tk.

If 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 that the image to be printed is rotated 180° from the original orientation and printed, and the paper is discharged without passing through the inversion path 44. The printing operation based on the control content of step S17 is the same as the printing operation of step S15 described above, except that the image to be printed is rotated 180° from the original orientation and printed. The description of "or invert front and back" in step S17 relates to the procedure of the operation performed by the printing device 1 of the third embodiment, so it will not be explained here.

Here, since T1<Tk, it is not possible to perform switching control 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 before the leading edge of the paper P reaches the switching unit 51 or the switching unit 53 controlled by the control unit 6. However, since T2≧Tk, by rotating the image to be printed 180° from the original orientation and printing it, it is possible to perform switching control 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 before the leading edge of the paper P reaches the switching unit 51 or the switching unit 53 controlled by the control unit 6, even if the paper P does not go through the inversion path 44. In other words, by rotating the image to be printed 180° from the original orientation and printing it, it is possible to secure time for inspection (image inspection) of the read data of the test image 61.

If it is determined in step S16 that T2<Tk (step S16: NO), in step S18, the control unit 6 determines the control content of the printing operation to print the image to be printed without rotation and to change at least one of the transport path and transport speed of the paper P before discharging it. The transport path can be changed, for example, to increase the transport distance of the paper P by transporting the paper P from the common discharge path 41 of the paper discharge unit 5 to the upstream discharge path 42 via the reversal path 44. The transport speed can be changed, for example, to decrease the transport speed of the paper P in the discharge conveying unit 31 by decreasing the transport speed in each path 41 to 44, 52 of the discharge conveying unit 31 of the paper discharge unit 5.

When the conveying distance of the paper P is increased in step S18, the control unit 6 sets the orientation of the switching unit 50 so that the paper P is guided from the lead-in roller pair 45 to the inversion path 44. As a result, the paper P is conveyed to the switching unit 51 or the switching unit 53 via the inversion path 44 in the paper discharge conveying unit 31.

When the conveying speed of the paper P in the paper discharge conveying section 31 is reduced in step S18, the control section 6 reduces the rotation speed of the roller pairs 45 to 49. This causes the paper P to be conveyed in the paper discharge conveying section 31 at a slower speed than normal.

Here, because T1<Tk and T2<Tk, even if the image to be printed is printed in the original orientation or rotated 180° from the original orientation, it is not possible to perform switching control of switching unit 51 or switching unit 53 based on the inspection results of the read data of test image 61 of paper P before the leading edge of the paper P reaches switching unit 51. In other words, even if the image to be printed is printed rotated 180° from the original orientation, it is not possible to secure time for inspection of the read data of test image 61 (image inspection).

When the paper P passes through the inversion path 44, the distance that the paper P is transported is 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 switchover arrival time is longer than the inspection time Tk, regardless of the position of the test image 61 on the paper P.

When the rotational speed of the roller pairs 45 to 49 is reduced, the time required to transport the paper P in the paper discharge transport section 31 is longer than when the rotational speed of the roller pairs 45 to 49 is not reduced. Therefore, when the rotational speed of the roller pairs 45 to 49 is reduced, the post-reading switchover arrival time is longer than the inspection time Tk, regardless of the position of the test image 61 on the paper P.

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

That is, the existing reversal path 44 is used as a path to buy time, or the transport speed of the paper P in the paper discharge transport section 31 is reduced to buy time. This makes the post-read 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 section 51 or the switching section 53, it becomes possible to control the switching of the switching section 51 or the switching section 53 based on the inspection results of the read data of the inspection image 61 of the paper P.

In step S18, the control unit 6 may control the image to be printed to be rotated 180° from its original orientation before printing.

In step S19, which follows steps S15, S17, and S18, the control unit 6 determines whether or not a switch will occur between stacking unit 32A, which is the destination for normal paper, and stacking unit 32B. The description of "or switching of the reading unit" in step S19 relates to the procedure of the operation performed by the printing device 1 of the third embodiment, and will not be explained here.

When the discharge destination of normal paper 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 paper is switched from stacking section 32A to stacking section 32B, so the control section 6 can determine whether the discharge destination of normal paper will be switched depending on whether the number of sheets discharged to stacking section 32A has reached a specified number.

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., stacking unit 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 continues to execute the printing operation according to the control contents of steps S15, S17, and S18.

When the number of sheets of paper P required for the print job has been printed by the printing unit 3 and ejected by the paper ejection unit 5, the series of operations is completed.

In the printing device 1 of the second embodiment described above, when printing the image to be printed including the test image 61, if the post-reading switchover arrival time when the image to be printed is printed on the paper P in its original orientation is less than the test time Tk, the control unit 6 determines whether it is possible to make the post-reading switchover arrival time equal to or greater than the test 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 switchover arrival time equal to or greater than the test 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 switchover arrival time is equal to or greater than the test time Tk.

This makes it possible to reduce the occurrence of situations in which time cannot be secured for image inspection without making the transport path from the reading units 22a and 22b to the switching unit 51 or the switching unit 53 excessively long. In addition, it is possible to reduce the occurrence of situations in which time cannot be secured for image inspection without using the reversing path 44 as a path for buying time.

Also, in the printing device 1 of this embodiment, if the post-reading switchover 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 switchover 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 transported to the switching unit 51 or the switching unit 53 via the reversal path 44 in the paper discharge transport unit 31, or to transport the paper P by reducing the transport speed in the paper discharge transport unit 31, or to transport the paper P by performing both of these, thereby controlling the paper P to be transported, so that the post-reading switchover arrival time is equal to or greater than the inspection time Tk.

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 degrees from its original orientation and printed on the paper P, time can be gained on the reversal 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 conveying of the paper P because it is not possible to ensure time for image inspection.

In addition, if the post-reading switchover 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 switchover arrival time cannot be made equal to or greater than the inspection time Tk even if the image to be printed is rotated 180 degrees 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 inspection image 61 in the image to be printed, so that the post-reading switchover arrival time is equal to or greater than the inspection time Tk.

Two or three of the above-mentioned controls may be combined: control in the discharge conveying section 31 to convey the paper P to the switching section 51 or the switching section 53 via the reversal path 44; control to adjust the conveying speed of the paper P in the discharge conveying section 31; and control to adjust and print the position of the test image 61 within the image to be printed.

The printing device 1 of the second embodiment can achieve the same effect as the printing device 1 of the first embodiment. That is, it is possible to reduce the occurrence of situations in which time cannot be secured for image inspection while suppressing the increase in size of the device and the increase in power consumption that occurs when the reversal path 44 is used as a path to buy time.

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, all of which have the same structure 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, some of the processing contents performed by the control unit 6 differ from those of the control unit 6 of the printing device 1 of the second embodiment.

When printing the image to be printed, including the test image 61, if the post-reading switchover arrival time when the image to be printed is printed on the paper P in its original orientation is less than the test time Tk, and if the post-reading switchover arrival time can be made equal to or greater than the test time Tk by printing the image to be printed on the paper P with the image to be printed reversed, the control unit 6 of this embodiment controls the printing unit 3 to print the image to be printed on the paper P with the image to be printed reversed so that the post-reading switchover arrival time is equal to or greater than the test time Tk.

Here, printing the image to be printed on the 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.

As shown in FIG. 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 transport unit 21. The position of the paper P when the upper reading unit 22a of the reading and transport unit 21 reads the test image 61 on the top surface of the paper P is a position closer (upstream) in the transport direction than the position of the paper P when the lower reading unit 22b of the reading and transport unit 21 reads the test image 61 on the bottom 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.

When the control unit 6 is controlling the switching unit 51, as shown in FIG. 8, 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 is L31. 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.

T1=L31/V...(9)
In the case where the control target of the control unit 6 is the switching unit 51, when the upper reading unit 22a reads the test image 61, the distance between the leading edge (downstream edge) of the paper P and the switching unit 51 is the distance L32. 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 end (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.

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

For example, a sheet of paper P on which an image to be printed has been printed on its front side Pa by single-sided printing with face-up paper ejection is transported with its front side Pa facing up by the reading and transporting unit 21, 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 (the front side 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.

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, as necessary, 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, so that the post-reading switching arrival time is equal to or longer than the test time Tk.

When the control unit 6 controls 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 distance L31, 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, T2 can be obtained. The leading edge (downstream end) of the paper P on which the 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 equal to the sum of the distance L31, L32 and the distance L13 from the time when the test image 61 was read.

The procedure of operation 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 procedure of operation 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 begins when a print job is input to the printing device 1 to print 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.

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 switchover 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, in step S13, the post-reading switchover 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).

Next, in step S14, the control unit 6 determines whether the post-reading switching 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.

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 its original orientation) and is discharged without passing through the inversion path 44.

Here, because T1≧Tk, it is possible to control switching of switching unit 51 or switching unit 53 based on the inspection results of the read data of test image 61 of paper P before the leading edge of paper P reaches switching unit 51 or switching unit 53 to be controlled. In other words, it is possible to secure time for inspection of the read data of test image 61 (image inspection).

If it is determined in step S14 that T1<Tk (step S14: NO), in step S16, the control unit 6 determines whether the post-reading switchover arrival time T2 when the image to be printed is printed on the paper P with the image reversed is equal to or greater than the inspection time Tk.

If 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 that the image to be printed is printed inverted and then discharged without passing through the inversion path 44. The printing operation according to the control content of step S17 is the same as the printing operation of step S15 described above, except that the image to be printed is printed inverted and then discharged.

Here, since T1<Tk, it is not possible to perform switching control of the switching unit 51 or the switching unit 53 based on the inspection results of the read data of the test image 61 of the paper P before the leading edge of the paper P reaches the switching unit 51 or the switching unit 53 controlled by the control unit 6. However, since T2≧Tk, by printing the image to be printed inverted, it is possible to perform switching control of the switching unit 51 or the switching unit 53 based on the inspection results of the read data of the test image 61 of the paper P before the leading edge of the paper P reaches the switching unit 51 or the switching unit 53 controlled by the control unit 6, even if the paper P does not go through the inversion path 44. In other words, by printing the image to be printed inverted, it is possible to secure time for inspection (image inspection) of the read data of the test image 61.

If it is determined in step S16 that T2<Tk (step S16: NO), in step S18, the control unit 6 determines the control content of the printing operation so that the image to be printed is printed without being turned over, and the paper is discharged by changing at least one of the transport path and the transport speed.

Here, because T1<Tk and T2<Tk, whether the image to be printed is printed in its original orientation or printed back-to-back, it is not possible to perform switching control of switching unit 51 or switching unit 53 based on the inspection results of the read data of test image 61 of paper P before the leading edge of paper P reaches switching unit 51 or switching unit 53. In other words, even if the image to be printed is printed back-to-back, it is not possible to secure time for inspection of the read data of test image 61 (image inspection).

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

In step S18, the control unit 6 may also control the printing of the image to be printed inverted.

In step S19, the control unit 6 determines whether switching between the reading units 22a and 22b that read the test image 61 will occur.

For example, when the image to be printed is printed on only one side of the paper P being 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 have been printed on the front side Pa of the paper P is printed on the back side Pb, and the test image 61 that should have been printed on the back side Pb is printed on the front side Pa. As a result, the front side reading unit that reads the test image 61 on the paper P being transported by the reading and transporting unit 21 switches from reading unit 22a to reading unit 22b, or from reading unit 22b to reading unit 22a. That is, a switch occurs in the surface to be read for reading the test image 61.

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 switchover 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 the image turned over, the reading units 22a, 22b that read the test image 61 are switched. Therefore, the control unit 6 can determine whether or not the reading units 22a, 22b that read the test image 61 will be switched 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 on the paper P with the image turned over.

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 switchover 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 is.

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 test 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 test 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 test 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 inverted.

This makes it possible to reduce the occurrence of situations in which time cannot be secured for image inspection without making the transport path from the reading units 22a and 22b to the switching unit 51 or the switching unit 53 excessively long. In addition, it is possible to reduce the occurrence of situations in which time cannot be secured for image inspection without using the reversing path 44 as a path for buying time.

In addition, in the printing device 1 of this embodiment, if the post-reading switchover 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 switchover 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 transported to the switching unit 51 or the switching unit 53 via the reversal path 44 in the paper discharge transport unit 31, or to transport the paper P by reducing the transport speed in the paper discharge transport unit 31, or to transport the paper P by performing both of these, thereby controlling the paper P to be transported, so that the post-reading switchover arrival time T1 is equal to or greater than the inspection time Tk.

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

In addition, if the post-reading switchover 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 switchover 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 to be printed inverted, 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 inspection image 61 within the image to be printed, so that the post-reading switchover arrival time T1 is equal to or greater than the inspection time Tk.

Two or three of the above-mentioned controls may be combined: control in the discharge conveying section 31 to convey the paper P to the switching section 51 or the switching section 53 via the reversal path 44; control to adjust the conveying speed of the paper P in the discharge conveying section 31; and control to adjust and print the position of the test image 61 within the image to be printed.

The printing device 1 of the third embodiment can achieve the same effects as the printing device 1 of the first and second embodiments. That is, it is possible to reduce the occurrence of situations in which time cannot be secured for image inspection, while suppressing the increase in size of the device and the increase in power consumption that occurs when the reversal path 44 is used as a path to buy time.

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 unit 2, a printing unit 3, and a paper discharge unit 5, which have the same structures as the printing device 1 of the second and third embodiments shown in Figures 1 and 4 (a) and (b). The printing device 1 of this embodiment differs from the control unit 6 of the printing device 1 of the second and third embodiments in the configuration of the reading units 22a and 22b of the image inspection unit 4, and in part of the content of the processing performed by the control unit 6.

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 multiple types of sensors that are used depending on the content of the inspection image 61 to be read. The reading units 221a and 222a are arranged with their positions shifted in the transport direction of the paper P in the reading and transporting unit 21. Like the reading unit 22a, the reading unit 22b also has two reading units 221b and 222b as multiple types of sensors that are used depending on the content of the inspection image 61 to be read. The reading units 221a and 222a are arranged with their positions shifted 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.

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

The reading units 221a and 221b arranged on the printing unit 3 side of each reading unit 22a and 22b are image sensors for full-surface inspection that read image images. 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 reading unit 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 capable of reading both one-dimensional 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.

The control unit 6 must 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.

As shown in FIG. 9, the time that the control unit 6 takes to perform a full-surface inspection using the read data from each reading unit 221a, 221b is proportional to the distance between each reading unit 221a, 221b and the switching unit 51. The time that the control unit 6 takes to perform a code inspection using the read data from each reading unit 222a, 222b is proportional to the distance between each reading unit 222a, 222b and the switching unit 51.

In the printing device 1 of this embodiment, double-sided printing of paper P is performed by the printing unit 3. On one of the front surface Pa and back surface Pb of 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 a smaller area than the image image for full-surface inspection is printed.

Therefore, if the test image 61 of the image is read by the reading unit 221a of the upper reading unit 22a, which is far from the switching unit 51 and therefore takes a long time to inspect, and the test image 61 of the code pattern is read by the reading unit 222b of the lower reading unit 22b, which is closer to the switching unit 51 and therefore takes a short time to inspect, then a long time can be ensured for inspecting the read data of the image.

In this 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 a longer test time Tk2 and the test image 61 read by the reading unit 22b has a shorter test time Tk1. Then, if it is possible to read the test image 61 with the long test time Tk2 by the reading unit 22a and the test image 61 with the short 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.

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.

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 the 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 the original orientation.

The control unit 6 can calculate the inspection times Tk1 and Tk2 corresponding to each of the reading units 22a and 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 and Tk2 based on information included in the print job indicating the size of the area of the test image 61 that is read by the reading units 22a and 22b, respectively, instead of the content of the test image 61.

In the next step S34, the control unit 6 determines whether the inspection time Tk1 corresponding to the reading unit 22a is longer than the inspection time Tk2 corresponding to the reading unit 22b.

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 its original orientation) and is discharged without passing through the inversion 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 its original orientation on each of the front surface Pa and back surface Pb of the paper P in the printing unit 3.

The paper P printed by the printing unit 3 passes through the image inspection unit 4 and is transported sequentially to the paper discharge unit 5. In the image inspection unit 4, the reading unit 22a reads the test image 61 on the top surface of each paper P that passes sequentially, and the reading unit 22b reads the test image 61 on the bottom surface of each paper P to generate respective read data.

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). The control unit 6 then 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.

Here, because Tk1>Tk2, it is possible to control the switching of the switching unit 51 based on the inspection results of the read data of each test image 61 on the front side Pa and back side Pb of the paper P before the leading edge of the paper P reaches the switching unit 51 to be controlled. In other words, it is possible to secure time for inspecting the read data of the test image 61 (image inspection).

If it is determined in step S34 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 so that the image to be printed is printed on the front surface Pa and the back surface Pb of the paper P so that the inspection time required to inspect the read data of the test image 61 read by the reading unit 22a is the inspection time Tk2 corresponding to the reading unit 22b calculated in step S33, and the inspection time required to inspect the read data of the test image 61 read by the reading unit 22b is 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 image to be printed is printed in a reversed state and discharged without passing through the reversal path 44. The printing operation according to the control content of step S36 is the same as the printing operation of step S35 described above, except that the image to be printed is printed in a reversed state.

In step S37 following steps S35 and 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 sheet). 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 the 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 sheet. If the information obtained by analyzing the read data of the test image 61 is abnormal for only one of 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 abnormal sheet.

The control unit 6 controls the switching unit 51 so that normal paper is discharged to the stacking unit 32A and abnormal paper is discharged to the purge discharge unit. Here, the control unit 6 sets the orientation of the switching unit 50 so that the paper 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 paper P that has reached the switching unit 53 is transported from the downstream discharge path 43 to the purge discharge path 52.

In the printing device 1 of the fourth embodiment described above, the control unit 6 makes the following judgment when printing the image to be printed including the inspection image 61 based on an image image for full-surface inspection on one of the front surface Pa and back surface Pb of the paper P, and printing the image to be printed 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 image to be printed is printed on the front surface Pa and back surface Pb of the paper P in the original orientation, the control unit 6 judges whether 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 image to be printed 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 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.

This makes it possible to reduce the occurrence of situations in which time cannot be secured for image inspection without making the transport path from the reading units 22a and 22b to the switching unit 51 excessively long. In addition, it is possible to reduce the occurrence of situations in which time cannot be secured for image inspection without using the reversing path 44 as a path to buy time.

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

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 have the same structure as the printing device 1 of the second and third embodiments shown in Figures 1 and 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 Figure 10.

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 side Pa and back side Pb of the paper P. On one of the front side Pa and back side Pb, a test image 61 of a two-dimensional code that requires a relatively long inspection time is printed, and on the other side, a test image 61 of a one-dimensional code that requires a relatively short inspection time is printed.

Therefore, if the upper reading unit 22a, which is far from the switching unit 51 and therefore has a long inspection time, reads the two-dimensional code inspection image 61, and the lower reading unit 22b, which is closer to the switching unit 51 and therefore has a short inspection time, reads the one-dimensional code inspection image 61 with 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.

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. 10.

In the printing device 1 of the fifth embodiment described above, the control unit 6 performs the following judgment when printing the image to be printed including the inspection image 61 of the two-dimensional code on one of the front surface Pa and the back surface Pb of the paper P and printing the image to be printed including the inspection image 61 of the one-dimensional code 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 image to be printed 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 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 image to be printed 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 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.

The printing device 1 of the fifth embodiment can achieve the same effects as the printing device 1 of the fourth embodiment.

In the above embodiment, the case where the reversing path 44 is used as a path for buying time has been described, but the path for buying time may not involve reversing the paper P. It is sufficient that the path for buying time is changed in part to 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.

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

Note that in a multi-page print job, if there is a page that satisfies the condition that the post-reading switchover 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 its original orientation and printed only for that page. Alternatively, in addition to the page that has a test image 61 that satisfies the condition, the image to be printed may also be rotated from its original orientation and printed for pages that do not have a test image 61 that satisfies the condition.

In the latter case, for example, if all pages of a print job are rotated from their original orientation before printing, it becomes unnecessary to change the source or destination of paper P depending on the print orientation, and the time required to feed or eject paper P can be reduced, improving the speed of the printing process.

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

In the above 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 be performed by an external device, and the control unit 6 may acquire the inspection results.

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

[Additional Notes]
This application discloses the following inventions.

(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.

(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.

(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 switching arrival time is changed according to the change in the reading target surface;
The printing device described in Appendix 1 or Appendix 2 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.

(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.

(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 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 portion 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.

(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.

(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.

REFERENCE SIGNS LIST 1 Printing device 2 Paper feed section 3 Printing section 4 Image inspection section 5 Paper discharge section 6 Control section 21 Reading and conveying section 22, 22a, 22b, 221a, 221b, 222a, 222b Reading section 31 Paper discharge conveying section 32A, 32B Stacking section 41 Common paper discharge path 42 Upstream paper discharge path 43 Downstream paper discharge path 44 Reversing path 45 Lead-in roller pair 46 Lifting roller pair 47 Upstream paper discharge conveying roller pair 48 Downstream paper discharge conveying roller pair 49 Reversing roller pair 50, 51, 53 Switching section 52 Purge paper discharge path 61 Inspection image P Paper Pa Paper surface Pb Paper back surface

Claims (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 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. 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. 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 switching 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. 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. 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. 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 reading unit 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;
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. 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 reading unit 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;
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.

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