Paper feeder

Abstract

To provide a paper feeder capable of performing paper feeding control in consideration of post-processing time without causing a decrease in productivity.SOLUTION: There is provided a paper feeder, including a paper feed unit 23 that sequentially feeds a plurality of print media, and a control unit 28 that controls the paper feed unit 23, in which when it is necessary to secure a preset post-processing paper feed interval Ts longer than a paper feed interval Tb in a process in which the control unit 28 sequentially feeds a plurality of print media at the paper feed interval Tb, a reference paper feed interval Tr based on the time when the paper feed interval Tb is multiplied by a natural number is compared with the post-processing paper feed interval Ts, and when the post-processing paper feed interval Ts is different from the reference paper feed interval tr, paper feeding is performed at the post-processing paper feed interval Ts.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a paper feeder that sequentially feeds a plurality of print media. [Background technology]

[0002] Conventionally, a printing system has been proposed in which a post-processing device is connected downstream of a printing device and performs various post-processing operations on printed sheets that have been printed in the printing device. Examples of post-processing operations performed in the post-processing device include stapling and punching.

[0003] In such a printing system, when post-processing is performed on printed paper, the post-processing device requires time depending on the processing content. Therefore, when transferring printed paper from the printing device to the post-processing device, it is necessary to ensure a time corresponding to the processing content. However, if the time until transferring printed paper from the printing device to the post-processing device is too long, productivity may decrease.

[0004] On the other hand, printing devices that perform double-sided printing are also used as printing devices connected to the above-mentioned post-processing devices. For example, a printing device that performs double-sided printing is proposed, which performs a printing process on one side of a print sheet fed from a paper feed unit of the printing device, turns the single-sided printed sheet over using a turnover unit, and then performs a printing process on the other side of the inverted single-sided printed sheet.

[0005] In order to improve productivity in such printing devices that perform double-sided printing, a method has been proposed in which single-sided printed sheets that have been inverted in a reversing unit are inserted between print sheets fed from a paper feed unit. That is, when double-sided printing is performed, as shown in Figure 4, a paper feed time Tp and a paper interval Tg for one print sheet are ensured between the first and second print sheets fed from the paper feed unit, and single-sided printed sheets that have been inverted in a reversing unit are inserted during this paper feed time Tp. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-73630 Summary of the Invention [Problem to be solved by the invention]

[0007] Even in the printing apparatus that performs double-sided printing described above, when a post-processing device is connected to perform post-processing, it is necessary to perform paper feed control taking the post-processing time into consideration.

[0008] For example, Patent Document 1 proposes a method of adjusting the paper interval Tg in accordance with the time required for post-processing performed for each print sheet when post-processing is performed for each print sheet.

[0009] However, post-processing may be performed not only for each printed sheet as described in Patent Document 1, but also for each set of multiple printed sheets. For example, there are cases where post-processing involves sheet alignment processing for each printed sheet, followed by stapling between sets.

[0010] In such a case, it is necessary to secure post-processing time for stapling between sets. Patent Document 1 proposes a method of securing post-processing time by adjusting the paper interval Tg in accordance with the post-processing time for paper alignment performed for each printed sheet, and multiplying (paper feed time Tp + paper interval Tg) × 2 = Tb by a natural number, as shown in Figure 12, for example.

[0011] However, when the timing for feeding the first printed sheet of the next set is determined by multiplying Tb by a natural number as described above, there may be a discrepancy between the feeding interval (Ts) from the feeding timing t0 of the printed sheet of the last page of the first set to the time t1 when stapling actually ends and the feeding interval obtained by multiplying Tb by a natural number, as shown in Fig. 12. In this case, productivity will decrease by the amount of the lost time (Tloss) shown in Fig. 12. Note that the example shown in Fig. 12 is an example in which the first set is made up of two printed sheets of paper.

[0012] SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a paper feeder that can perform paper feed control taking post-processing time into consideration without causing a decrease in productivity. [Means for solving the problem]

[0013] The paper feeding device of the present invention includes a paper feeding unit that sequentially feeds multiple printing media, and a control unit that controls the paper feeding unit. When the control unit needs to ensure a predetermined second paper feeding interval that is longer than the first paper feeding interval during the process of sequentially feeding multiple printing media at a first paper feeding interval, the control unit compares a third paper feeding interval based on the point in time when the first paper feeding interval is multiplied by a natural number with the second paper feeding interval, and if the second paper feeding interval differs from the third paper feeding interval, the control unit feeds at the second paper feeding interval. [Effects of the Invention]

[0014] According to the paper feeding device of the present invention, in the process of sequentially feeding a plurality of printing media at a first paper feeding interval, if it is necessary to ensure a preset second paper feeding interval longer than the first paper feeding interval (for example, the paper feeding interval until post-processing is completed), a third paper feeding interval based on the point in time when the first paper feeding interval is multiplied by a natural number is compared with the second paper feeding interval, and if the second paper feeding interval differs from the third paper feeding interval, paper is fed at the second paper feeding interval.Therefore, when performing double-sided printing and post-processing as shown in Figure 12, for example, by starting feeding of the first sheet of printing paper of the second copy at point t1 when stapling is completed, it is possible to prevent the occurrence of lost time Tloss, and paper feeding control can be performed that takes post-processing time into consideration without reducing productivity. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a printing system using an embodiment of a paper feeder of the present invention; [Figure 2] A block diagram showing the schematic configuration of the control system of the printing system shown in Figure 1. [Figure 3] FIG. 10 is a diagram showing an example of paper feed control in the case of printing conditions of "single-sided printing, no post-processing" [Figure 4] FIG. 10 is a diagram showing an example of paper feed control in the case of printing conditions of "double-sided printing, no post-processing" [Figure 5] FIG. 10 is a diagram showing an example of the transport state of print paper on the circulating transport path during double-sided transport. [Figure 6] FIG. 10 is a diagram showing an example of paper feed control in the case of printing conditions of "double-sided printing, with post-processing" [Figure 7] Flowchart for explaining how to determine the timing of feeding the first sheet of the second set [Figure 8] FIG. 10 is a diagram showing another example of paper feed control for the printing conditions "double-sided printing, with post-processing" [Figure 9] A flowchart for explaining a modified method for determining the timing of feeding the first sheet of the second set. [Figure 10] FIG. 10 is a diagram illustrating an example of a method for determining the timing of feeding the first sheet of the second set based on the detection result of the registration sensor. [Figure 11] FIG. 10 is a diagram for explaining another example of a method for determining the timing of feeding the first sheet of the second set based on the detection result of the registration sensor. [Figure 12] FIG. 1 is a diagram illustrating conventional paper feed control. DETAILED DESCRIPTION OF THE INVENTION

[0016] A printing system using an embodiment of a paper feeder of the present invention will be described in detail below with reference to the drawings. The printing system of this embodiment is characterized by a method for controlling the paper feed timing of the paper feeder, but first, the configuration of the entire system will be described. Figure 1 is a schematic diagram of the overall configuration of a printing system 1 of this embodiment.

[0017] As shown in FIG. 1, the printing system 1 of this embodiment includes a computer 10, a printing device 20, and a post-processing device 30.

[0018] The computer 10 and the printing device 20 are connected via a communication line. The communication line may be an internet line, a LAN (Local Area Network), or a telephone line. The communication line may be wired or wireless.

[0019] The computer 10 is configured to be able to edit image data to be printed on printing paper. A printer driver for the printing device 20 is installed on the computer 10, which generates print job data including image data and outputs the generated print job data to the printing device 20. In addition to the image data described above, the print job data also includes information indicating double-sided or single-sided printing, information indicating paper size, and information indicating post-processing details.

[0020] The printing device 20 performs a printing process on printing paper based on the print job data output from the computer 10. The printing device 20 is equipped with an ink head unit 21 that ejects ink onto printing paper. The ink head unit 21 performs a printing process by ejecting ink onto printing paper based on image data included in the print job data output from the computer 10. The ink head unit 21 of this embodiment is equipped with multiple line-type ink heads that eject ink of each color: black (K), cyan (C), magenta (M), and yellow (Y).

[0021] The printing device 20 also includes a paper feed tray 22 on which printing paper is placed, and a paper feed unit 23 that removes and feeds printing paper placed in the paper feed tray 22. Printing paper of various paper types and sizes is placed in the paper feed tray 22. When printing processing is performed in the printing device 20, printing paper placed in the paper feed tray 22 is picked up by the paper feed unit 23, which is equipped with a pick roller and the like, and fed to a circulating conveyance path 24, which will be described later.

[0022] The printing device 20 also has a circulating conveyance path 24 that conveys the printing paper fed by the paper feed unit 23. The circulating conveyance path 24 is made up of conveyance rollers and conveyance belts, and conveys the printing paper fed from the paper feed tray 22 from the upstream side to the downstream side of the ink head unit 21.

[0023] In the case of single-sided printing, the circulating conveying path 24 passes the print paper, one side of which has been printed by the ink head unit 21, directly to the post-processing device 30 via the connecting path 25. In the case of double-sided printing, the circulating conveying path 24 conveys the print paper, one side of which has been printed, to the reversing unit 26, and then conveys the single-sided printed paper, which has been turned over in the reversing unit 26, from the upstream side to the downstream side of the ink head unit 21 again, and then passes the double-sided printed paper, which has been printed again by the ink head unit 21, to the post-processing device 30 via the connecting path 25.

[0024] A registration sensor 27 is provided near the junction of the circulating transport path 24 and the paper feed transport path 23a, which transports printing paper fed from the paper feed unit 23 to the circulating transport path 24. The registration sensor 27 is an optical paper detection sensor that detects whether the printing medium has passed the position of the registration sensor 27. In this embodiment, the registration sensor 27 corresponds to the detection unit of the present invention.

[0025] The detection signal from the registration sensor 27 is output to a control unit 28 (described later), which controls the paper feed unit 23 to control the paper feed timing based on the input detection signal. The control of the paper feed timing based on the detection signal from the registration sensor 27 will be described in detail later, but the control of the paper feed interval by the control unit 28 (described later) is based on the detection signal from the registration sensor 27. That is, in this embodiment, the point in time when the front or back surface of the print medium in the present invention passes a predetermined position is the point in time when it passes the registration sensor 27, and the paper feed interval is the interval between the points of time when it passes the registration sensor 27.

[0026] The post-processing device 30 performs predetermined post-processing on printed sheets handed over from the printing device 20. Examples of post-processing performed by the post-processing device 30 include stapling, which staples multiple printed sheets together; offsetting, which offsets each set and discharges them to a paper output tray; punching, which punches holes in printed sheets; folding, which folds printed sheets in thirds or in half; and bookbinding, which binds printed sheets together. In addition to the post-processing performed for each set as described above, there is also post-processing performed for each printed sheet within a set, such as sheet alignment. The specific mechanisms for performing these post-processing operations can be well-known, and detailed descriptions thereof will be omitted here.

[0027] Next, the control system in the printing system 1 of this embodiment will be described with reference to FIG.

[0028] 2, the printing device 20 is equipped with a control unit 28 that controls the entire printing device 20. The control unit 28 controls the timing of feeding printing paper by the paper feed unit 23, the transport of printing paper by the circulating transport path 24, the ejection of ink from the ink head unit 21, and the like.

[0029] Furthermore, control unit 28 is provided with post-processing paper feed interval storage unit 28a that stores a post-processing paper feed interval calculated in advance based on the post-processing time in post-processing device 30. When post-processing is performed in post-processing device 30, control unit 28 reads out the post-processing paper feed interval stored in post-processing paper feed interval storage unit 28a and controls the paper feed timing, and the method for controlling the paper feed timing will be described in detail later.

[0030] Next, we will explain the operation of the printing system 1 of this embodiment. Note that the printing system 1 of this embodiment is characterized by a method for controlling the timing of feeding print paper in the printing device 20, so the following explanation will focus on this point.

[0031] The printing system 1 of this embodiment is capable of single-sided printing and double-sided printing, and can perform post-processing on printed paper after either printing. That is, the printing system 1 of this embodiment has four printing conditions: "single-sided printing, no post-processing," "double-sided printing, no post-processing," "single-sided printing, with post-processing," and "double-sided printing, with post-processing." The printing system 1 of this embodiment is characterized by the paper feed timing for the printing condition "double-sided printing, with post-processing," but for ease of understanding, the paper feed control of the printing device 20 for each of the four printing conditions will be described below.

[0032] First, in the case of the printing conditions of "single-sided printing, no post-processing," control is performed so that each print sheet is fed from paper feed unit 23 at a paper feed interval Ta, as shown in Figure 3. Paper feed interval Ta is the sum of paper feed time Tp and paper interval Tg. Paper feed time Tp is the value obtained by dividing the length of one print sheet in the transport direction by the transport speed of circulating transport path 24. This time is set based on paper size information included in the print job data.

[0033] Furthermore, the paper spacing Tg is a preset paper spacing, and in this embodiment, in the case of the printing conditions of "single-sided printing, no post-processing", it is set to the shortest spacing at which printing papers do not collide with each other.

[0034] Next, in the case of the printing conditions of "double-sided printing, no post-processing," as shown in FIG. 4, control is performed so that each print sheet is fed from the paper feed unit 23 at a paper feed interval Tb. The paper feed interval Tb is twice the paper feed interval Ta under the printing conditions of "single-sided printing, no post-processing" described above. Between print sheets fed from the paper feed unit 23, a paper feed time Tp for one print sheet and a paper interval Tg before and after it are ensured. During this paper feed time Tp, a single-sided printed sheet that has been inverted in the reversing unit 26 of the circulating conveyance path 24 is inserted and conveyed. That is, in this embodiment, during double-sided printing, the feeding of unprinted print sheets from the paper feed unit 23 and the feeding of single-sided printed sheets from the reversing unit 26 of the circulating conveyance path 24 are alternately performed.

[0035] In this embodiment, as shown in FIG. 5, in addition to the print paper (third print paper) directly below the ink head unit 21, two print papers (first print paper and second print paper) are transported on the upper circulating transport path 24. That is, a total of three print papers can be transported simultaneously on the circulating transport path 24. Therefore, as shown in FIGS. 4 and 5, immediately after the third unprinted print paper (third print paper front) is fed from the paper feed unit 23, the first single-sided printed paper (first print paper back) is inserted, and immediately after the fourth unprinted print paper (fourth print paper front) is fed from the paper feed unit 23, the second single-sided printed paper (second print paper back) is inserted. That is, immediately after the nth print paper is fed from the paper feed unit 23, the n-2th single-sided printed paper is inserted. The dotted square in FIG. 4 indicates a time period in which the paper feed time Tp plus the paper interval Tg before and after it is secured, but in reality the print paper is not transported.

[0036] Next, we will explain paper feed control for the printing conditions of "double-sided printing with post-processing." Here, we will explain paper feed control when one set is made up of 10 double-sided printed sheets, and as post-processing, paper alignment processing is performed for each printed sheet and stapling processing is performed for each set. In other words, we will explain paper feed control when paper alignment processing is performed between printed sheets and stapling processing is performed between sets.

[0037] As shown in Fig. 6, for the first copy, from the feeding of the front side of the first print sheet to the feeding of the front side of the tenth print sheet, control unit 28 controls so that each print sheet is fed from paper feed unit 23 at paper feed intervals Tb, similar to the case of the printing conditions of "double-sided printing, no post-processing" shown in Fig. 4. Note that paper intervals Tg are adjusted to match the time for paper alignment processing, which is post-processing for each print sheet.

[0038] Here, when stapling is performed between copies, if the paper feed timing for the first printed sheet of the second copy is simply set to a natural number multiple of (Tp+Tg)×2=Tb, this will result in the "conventional first sheet, front side" paper feed timing shown in Fig. 6. However, if the stapling of the first copy ends at time t1 shown in Fig. 6, for example, a loss of time equal to the Tloss shown in Fig. 6 will occur, resulting in a decrease in productivity. Therefore, in this embodiment, the paper feed timing is controlled so that the loss of time Tloss described above does not occur.

[0039] Specifically, the control unit 28 determines the timing for feeding the first printing sheet of the second copy in accordance with the flowchart shown in FIG.

[0040] First, the control unit 28 reads out the post-processing paper feed interval Ts from the post-processing paper feed interval storage unit 28a. The post-processing paper feed interval Ts is the time from the time when the feeding of the print paper for the last page of the first set (the front side of the tenth sheet) is completed (t0 shown in FIG. 6) to the time when the stapling process for the first set is completed (t1 shown in FIG. 6), and is stored in advance in the post-processing paper feed interval storage unit 28a.

[0041] The post-processing paper feed interval Ts is a paper feed interval that is set based on the post-processing time that starts after the last page of the first set is ejected and ends when post-processing is completed, and is a paper feed interval that is set so that the next set of printed paper is not handed over to the post-processing device 30 while the post-processing device 30 is performing post-processing. The post-processing paper feed interval Ts in this embodiment corresponds to the paper feed interval that corresponds to the post-processing time of the present invention.

[0042] The control unit 28 then calculates a reference paper feed interval Tr by adding the paper interval Tg to the time from the time (t0) when feeding of the print paper for the last page of the first set (the front side of the tenth sheet) is completed to the time (t2) when feeding of the print paper for the back side of that last page (the back side of the tenth sheet) is completed, and compares the magnitude of the post-processing paper feed interval Ts with the reference paper feed interval Tr (S10). Note that the comparison of the reference paper feed interval Tr with the post-processing paper feed interval Ts essentially determines whether print paper is present on the circulating conveyance path 24 when stapling of the first set is completed. In this embodiment, the paper feed interval Tb corresponds to the first paper feed interval of the present invention, the post-processing paper feed interval Ts corresponds to the second paper feed interval of the present invention, and the reference paper feed interval Tr corresponds to the third paper feed interval of the present invention.

[0043] If the post-processing paper feed interval Ts is longer than the standard paper feed interval Tr (S10, YES), that is, if there is no printing paper on the circulating conveying path 24 at the time t1 when the stapling process for the first copy is completed, there is no problem in starting to feed the first printing paper of the second copy when the stapling process for the first copy is completed, and therefore, as shown in Figure 6, the control unit 28 sets the paper feed interval Tg' for the first printing paper of the second copy to the post-processing paper feed interval Ts (S12).

[0044] On the other hand, as shown in Fig. 8, if the post-processing paper feed interval Ts is shorter than the reference paper feed interval Tr (S10, NO), that is, if there is still print paper on the circulating conveyance path 24 when stapling of the first copy is completed, the control unit 28 sets the paper feed interval Tg' for the first print paper of the second copy to {Tg + (Tp + Tg) × N} (S14), as shown in Fig. 8, to prevent that print paper from colliding with the first print paper of the second copy, where N is the smallest odd number that makes Tg' longer than Ts.

[0045] Then, control unit 28 starts feeding the first printing paper of the second copy from paper feed unit 23 using the paper feed interval Tg' set in S12 or S14. Then, the second and subsequent printing papers of the second copy are fed at paper feed interval Tb.

[0046] According to the printing system 1 of the above embodiment, the standard paper feed interval Tr is compared with the post-processing paper feed interval Ts, and if the post-processing paper feed interval Ts is equal to or greater than the standard paper feed interval Tr, as shown in FIG. 6, the first sheet of printing paper for the second copy is fed at the post-processing paper feed interval Ts. This prevents the occurrence of lost time Tloss, and enables paper feed control that takes post-processing time into consideration without reducing productivity.

[0047] Furthermore, in the printing system 1 of the above embodiment, when the post-processing paper feed interval Ts is shorter than the standard paper feed interval Tr, as shown in FIG. 8, the paper is fed at the standard paper feed interval Tr, so that the first printing paper of the second copy can be fed without the printing paper of the last page of the first copy (the back of the 10th sheet) colliding with the first printing paper of the second copy.

[0048] In the case of printing conditions of "single-sided printing with post-processing," for example, the paper interval Tg shown in FIG. 3 is adjusted to match the post-processing time for each print sheet, and each print sheet is fed from the paper feed unit 23. The present invention is also applicable to the case of "single-sided printing with post-processing." For example, when paper is fed from the paper feed unit 23 at a paper feed interval Ta as shown in FIG. 3, after the last page of the first copy is fed, the feed time of the first sheet of the second copy, which is a natural number multiple of the paper feed interval Ta (third paper feed interval), may be later than the end of post-processing. In other words, the post-processing paper feed period (second paper feed period) corresponding to the post-processing time may be shorter than the paper feed period (third paper feed period) corresponding to a natural number multiple of the paper feed interval Ta. Even in this case, by adjusting the feed timing of the first print sheet of the second copy to coincide with the end of post-processing, lost time can be prevented and productivity can be improved.

[0049] Next, a modified example of the paper feed timing for the printing conditions of "double-sided printing, with post-processing" in the above embodiment will be described. In the above embodiment, for example, in the example shown in Fig. 6, the paper feed interval Tg' for the first printed sheet of the second copy is set to the post-processing paper feed interval Ts, assuming that the printed sheet of the last page of the first copy (the back of the tenth sheet) has already passed through the circulating conveyance path 24. However, if the printed sheet of the last page of the first copy is not conveyed as scheduled and a conveyance delay occurs, a collision will occur between the printed sheet of the last page of the first copy (the back of the tenth sheet) and the first printed sheet of the second copy.

[0050] Therefore, the control unit 28 sets the paper feed interval Tg' as shown in the flowchart of FIG. 9, and then determines whether the printing paper of the last page of the first set (the back of the 10th sheet) has passed the position of the registration sensor 27 based on the detection signal detected by the registration sensor 27 shown in FIG. 1 (S16).

[0051] In the example shown in FIG. 6, if the printing paper of the last page of the first set (the back of the 10th sheet) has not passed the position of the registration sensor 27 when the paper feed interval Tg' has elapsed, the process waits until it passes (S16, NO).

[0052] Then, as shown in FIG. 10, at time t3 when the printing paper of the last page of the first copy (the back of the 10th sheet) passes the position of the registration sensor 27 (S16, YES), the control unit 28 starts feeding the first printing paper of the second copy from the paper feed unit 23.

[0053] On the other hand, if the printing paper of the last page of the first copy (the back of the 10th sheet) has passed the position of the registration sensor 27 when the paper feed interval Tg' has elapsed, the control unit 28 starts feeding the first printing paper of the second copy from the paper feed unit 23 in accordance with the paper feed interval Tg' set in S12 or S14.

[0054] Note that Figure 10 shows an example where the paper feed interval Tg' is set to the post-processing paper feed interval Ts (in the case of S12), but even when the paper feed interval Tg' is set to {Tg + (Tp + Tg) × N} (in the case of S14), the control unit 28 starts feeding the first printing paper of the second copy from the paper feed unit 23 at time t4 when the printing paper of the last page of the first copy (the back of the 10th sheet) passes the position of the registration sensor 27 (S16, YES), as shown in Figure 11.

[0055] As described above, if the passage of the printing medium of the last page of the first copy has not been detected by the registration sensor 27 when the paper feed interval Tg' has elapsed, the feeding of the first sheet of printing medium of the second copy is started after the passage of the printing medium of the last page is detected, thereby more reliably avoiding a collision between the printing paper of the last page of the first copy and the first sheet of printing paper of the second copy.

[0056] The above embodiment is an example in which the double-sided printing device of the present invention is applied to an inkjet printing device, but the printing method is not limited to the inkjet method, and the double-sided printing device of the present invention may also be applied to a laser method or a stencil printing method printing device.

[0057] The following additional notes are also disclosed regarding the paper feeding device of the present invention. (Addendum)

[0058] In the paper feeding device of the present invention, the first paper feed interval can be the paper feed interval of the paper feed unit when double-sided transport is performed, alternating between feeding printing media from the paper feed unit and feeding inverted printing media; the second paper feed interval can be the paper feed interval corresponding to the time for post-processing when post-processing is performed on the printed printing media of the first copy between the first copy and the second copy printed after the first copy; and the third paper feed interval can be the paper feed interval from the time when the front side of the printing media of the last page of the first copy passes a predetermined position to the time when the back side of the inverted printing media of the last page of the first copy passes a predetermined position, which is a natural number multiple of the first paper feed interval.

[0059] In addition, in the paper feeding device of the present invention, the first paper feed interval can be the paper feed interval of the paper feed unit when double-sided transport is performed, in which the feeding of printing media from the paper feed unit and the feeding of inverted printing media are alternately performed; the second paper feed interval can be the paper feed interval corresponding to the time for post-processing when post-processing is performed on the printed printing media of the first copy between the first copy and the second copy printed after the first copy; the third paper feed interval can be the paper feed interval from the time when the front side of the printing media of the last page of the first copy passes a predetermined position to the time when the back side of the inverted printing media of the last page of the first copy passes a predetermined position, which is a natural number multiple of the first paper feed interval; and the control unit can feed paper at the third paper feed interval if the second paper feed interval is shorter than the third paper feed interval.

[0060] In addition, the paper feeding device of the present invention can be provided with a detection unit that detects whether the printing medium has passed a predetermined position, and when printing a second copy after printing a first copy, and feeding the first sheet of printing medium of the second copy at a second paper feeding interval, if the printing medium of the final page of the first copy has not been detected by the detection unit when the second paper feeding interval has elapsed, the control unit can start feeding the first sheet of printing medium of the second copy after waiting for the detection of the printing medium of the final page. [Explanation of symbols]

[0061] 1 Printing System 10. Computers 20 Printing device 21 Ink head unit 22 Paper tray 23 Paper feed section 23a Paper feed path 24 Circulation conveying path 25 Access Road 26 Reversal section 27 Resist Sensor 28 Control Unit 28a Post-processing paper feed interval memory unit 30 Aftertreatment device

Claims

1. a paper feed unit that sequentially feeds a plurality of print media; a control unit that controls the paper feed unit to alternately feed print media from the paper feed unit and feed print media obtained by inverting the fed print media in a reversing unit at a first paper feed interval; a control unit that sequentially feeds the printing media in units of a set consisting of a plurality of the printing media using the first paper feed interval, and when it is necessary to ensure a second paper feed interval corresponding to a predetermined post-processing time longer than the first paper feed interval during the process of performing post-processing between the first and second sets, compares the second paper feed interval with a third paper feed interval obtained by adding the paper interval to the time from when paper feed of the front side of the printing media of the last page of the first set is completed to when paper feed of the back side of the printing media of the last page is completed after the printing media is turned over, and when the second paper feed interval is equal to or greater than the third paper feed interval, feeds the printing media of the first page of the second set at the second paper feed interval, and when the second paper feed interval is less than the third paper feed interval, feeds the printing media of the first page of the second set at the third paper feed interval.

2. a detection unit that detects whether the print medium has passed a predetermined position; A paper feeding device as described in claim 1, wherein when the control unit feeds the first sheet of printing media of the second copy at the second paper feed interval, if the printing media of the last page of the first copy has not been detected by the detection unit when the second paper feed interval has elapsed, the control unit starts feeding the first sheet of printing media of the second copy after waiting for the detection of the printing media of the last page.

3. a paper feed unit that sequentially feeds a plurality of print media; a control unit that controls the paper feed unit to feed the print medium from the paper feed unit at a first paper feed interval; When the control unit sequentially feeds the printing media in units of a set consisting of a plurality of the printing media using the first paper feed interval and performs post-processing between the first set and the second set, it is necessary to ensure a second paper feed interval that corresponds to a predetermined post-processing time that is longer than the first paper feed interval, A paper feeding device that compares the second paper feed interval with a third paper feed interval, which is the first paper feed interval multiplied by a natural number equal to the number of sheets of printing media in the first copy, and if the second paper feed interval is shorter than the third paper feed interval, feeds the printing media of the first page of the second copy at the second paper feed interval.

Images