JP2011143555A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer which can reduce damage caused by a jam while shortening a time to complete printing. <P>SOLUTION: A perfecting printer 1 includes a paper feeding unit 2 which feeds printing paper PA, a plurality of paper sensors 26, 27, 34, 44 and 52 arranged on the transport path of the printing paper PA and outputting a detection signal by detecting the printing paper PA, and a control unit 9 which controls the paper feeding unit 2 and determines the jam of the printing paper PA based on detection signals inputed from the paper sensor 26, 27, 34, 44 or 52, where the control unit 9 stores a jam table on which jam levels Lvn of the paper sensors 26, 27, 34, 44 and 52 are set based on the occurrence of jam, and has an interval mode for feeding the next printing paper PA by controlling the paper feeding unit 2 when it is determined that the printing paper PA is detected by the paper sensor 26, 27, 34, 44 or 52 having the highest jam level Lvn. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing apparatus provided with medium detection means such as a paper sensor for detecting clogging of a print medium.

  A printing apparatus that prints an image while conveying a print medium is known. In such a printing apparatus, clogging of the printing medium being conveyed (hereinafter referred to as jam) is a problem.

  Patent Document 1 discloses a printing apparatus for reducing damage when a jam occurs. Specifically, the printing apparatus described in Patent Document 1 is configured to start conveyance of the next print sheet when the discharge of the print sheet is detected by a discharge detection unit provided in the discharge unit. Has been. As a result, the printing apparatus of Patent Document 1 further suppresses an increase in jam damage by further transporting printing paper in a state where a jam has occurred.

JP 2004-326262 A

  However, the technique disclosed in Patent Document 1 has a problem that after the previous print sheet is discharged, the time until the printing of all pages is completed increases in order to start transporting the next print sheet.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a printing apparatus capable of reducing jam damage while shortening the time until printing is completed.

  In order to achieve the above object, a first feature of a printing apparatus according to the present invention is a plurality of paper feed units that feed a print medium, and a plurality of detection signals that are output by detecting the print medium that is transported through the transport path. And a control unit for controlling the paper feeding unit to feed the print medium and detecting a jam of the print medium based on a detection signal input from the medium detection unit, The control unit stores a jam table in which the jam level of the medium detection unit is set based on the number of jam occurrences, and determines that the print medium has been detected by the medium detection unit having the highest jam level. The next print medium is fed by controlling the paper section.

  The medium detection means includes a light-emitting / receiving (shielding) sensor that turns off the detection signal when the print medium passes, and a reflection that turns on the detection signal when the print medium passes. A type sensor or the like can be applied. Further, as a jam detection method, a method for determining whether the jam is normal or jammed based on the length of the print medium calculated from the leading edge and the trailing edge of one print medium detected by the medium detection means, or a detection by the medium detection means. It is possible to apply a method for determining whether the print medium is normal or jammed based on the interval between the two print media calculated from the rear end of the previous print medium and the front end of the subsequent print medium. Furthermore, as another jam detection method, the length of the print medium and the interval between the print media, that is, the time when the leading edge of the previous print medium is detected by the upstream medium detection means within a predetermined time from the downstream side. A method of determining whether the jam is normal or jammed by detecting the leading edge of the next print medium by the medium detecting means can be applied.

  The second feature of the printing apparatus according to the present invention is further provided with input means for inputting a change in jam level, and the control unit rewrites the jam table with the jam level changed by the input means.

  Further, a third feature of the printing apparatus according to the present invention is that the control unit has the highest jam level among the medium detection means arranged on the upstream side of the transport path from the medium detection means with the highest jam level. When the print medium is detected by the medium detection means, the paper feed unit is controlled to feed the next print medium.

  According to a fourth aspect of the printing apparatus of the present invention, when the control unit determines that the print medium has been detected a predetermined number of times by the medium detection unit having the highest jam level when performing duplex printing, The paper feeding unit is controlled to feed the next print medium.

  According to the first feature of the present invention, the control unit feeds the next print medium when the print medium is detected by the medium detection unit having the highest jam level. As a result, the first feature can shorten the time until the printing is completed while reducing the damage caused by the jam.

  According to the second feature of the present invention, since the input means for inputting the change of the jam level is provided, it is possible to flexibly cope with the user's desire to change the paper feed timing.

  According to the third aspect of the present invention, when the print medium is detected by the medium detection means upstream of the medium detection means having the highest jam level, the control section feeds the next print medium. As a result, the third feature can also be applied to a user who desires to shorten the printing completion time.

  According to the fourth aspect of the present invention, in double-sided printing, when the print medium is detected a predetermined number of times by the medium detection unit having the highest jam level, the next print medium is fed. Damage can be further reduced.

1 is an overall schematic diagram of a duplex printing apparatus according to a first embodiment. It is a block diagram for demonstrating the control system of a duplex printing apparatus. It is a figure for demonstrating a jam table. 5 is a flowchart of printing paper feeding processing. It is a flowchart of single-sided paper feed processing in a normal mode. It is a flowchart of double-sided paper feed processing in a normal mode. It is a flowchart of the single-sided paper feed processing in the interval mode. It is a flowchart of double-sided paper feed processing in interval mode. 10 is a flowchart of single-sided paper feed processing in a high-speed interval mode. 6 is a flowchart of double-sided paper feed processing in a high-speed interval mode. It is a flowchart of a jam level change process.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a double-sided printing apparatus will be described with reference to the drawings. FIG. 1 is an overall schematic diagram of a duplex printing apparatus according to a first embodiment. FIG. 2 is a block diagram for explaining a control system of the duplex printing apparatus. FIG. 3 is a diagram for explaining a jam table. In the following description, the paper surface direction of FIG. Moreover, as shown in FIG. 1, when viewed from the user, the top, bottom, left, and right are defined as the top, bottom, left and right directions.

  Note that a path indicated by a thick line in FIG. 1 is a transport path through which the printing paper is transported. A route indicated by a solid line among the transport routes is a normal route RC. The route indicated by the alternate long and short dash line in the transport route is the reverse route RR. A path indicated by a dotted line in the transport path is a paper discharge path RD. A path indicated by a two-dot chain line in the transport path is a paper feed path RS. In the following description, upstream and downstream mean upstream and downstream in the transport path.

  Here, in the case of single-sided printing, the printing paper (corresponding to the print medium in the claims) PA is conveyed in the order of the paper feed path RS, the normal path RC, and the paper discharge path RD. In duplex printing, the printing paper PA is conveyed in the order of the paper feed route RS, the normal route RC, the reverse route RR, the normal route RC, and the paper discharge route RD.

  As shown in FIGS. 1 and 2, the duplex printing apparatus 1 according to the first embodiment includes a paper feeding unit 2, a conveyance printing unit 3, a rising conveyance unit 4, a horizontal conveyance unit 5, and a paper discharge unit 6. , A reversing unit 7, an input display unit 8, a control unit 9, and a housing 10 for housing each unit.

  The paper feed unit 2 transports and feeds the printing paper PA. The paper feed unit 2 is arranged on the most upstream side of the transport path. The paper feed unit 2 includes a side paper feed tray 11, three internal paper feed trays 12, a side paper feed roller 13, a side paper feed motor 14, a plurality of pairs of internal paper feed rollers 15, and an internal paper feed. A motor 16, a merging paper feeding roller 17, and a merging paper feeding motor 18 are provided.

  The paper feed trays 11 and 12 are used to load print paper PA for paper feed.

  The side paper feed roller 13 feeds the printing paper PA stacked on the side paper feed tray 11 to the transport printing unit 3. The side paper feed roller 13 is disposed along a paper feed path RS between the downstream end of the side paper feed tray 11 and the registration roller 21 of the transport printing unit 3. The side paper feed roller 13 is rotationally driven by a side paper feed motor 14.

  The internal paper feed roller 15 conveys the printing paper PA stacked on any of the internal paper feed trays 12 to the merging paper feed roller 17. The internal paper feed roller 15 is disposed along any one of the multiple paper feed paths RS between the downstream ends of the multiple internal paper feed trays 12 and the merge paper feed roller 17. The internal paper feed roller 15 is rotationally driven by an internal paper feed motor 16.

  The merge paper feeding roller 17 feeds the printing paper PA conveyed from the internal paper feeding roller 15 to the conveyance printing unit 3. The merge paper feed roller 17 is disposed on a paper feed path RS between the internal paper feed roller 15 and the registration roller 21 of the transport printing unit 3. The merge paper feed roller 17 is rotationally driven by a merge paper feed motor 18.

  The transport printing unit 3 prints an image while transporting the printing paper PA. The transport printing unit 3 is disposed on the downstream side of the paper feeding unit 2. The conveyance printing unit 3 includes a registration roller 21, a registration motor 22, a belt conveyance unit 23, a belt motor 24, an inkjet head unit 25, and paper sensors (corresponding to the medium detection means in claims) 26 and 27. I have.

  The registration roller 21 supplies the printing paper PA fed from the paper feeding unit 2 to the belt conveyance unit 23. The registration roller 21 refeeds the printing paper PA conveyed from the reversing unit 7 to the belt conveyance unit 23. The registration roller 21 is disposed on the normal route RC upstream of the transport printing unit 3. In other words, the registration roller 21 is disposed in the vicinity of the junction point between the sheet feeding path RS and the reversing path RR. The registration roller 21 is rotationally driven by a registration motor 22.

  The belt conveyance unit 23 conveys the printing paper PA to the ascending conveyance unit 4 while sucking the lower surface of the printing paper PA conveyed from the registration roller 21 by the endless belt. The belt conveyance unit 23 is disposed on the downstream side of the normal path RC from the registration rollers 21. The belt conveyance unit 23 is disposed below the normal route RC. The belt conveying unit 23 is driven by a belt motor 24 that conveys the printing paper PA.

  The inkjet head unit 25 includes a plurality of line-type inkjet heads (not shown). The inkjet head unit 25 is disposed on the side opposite to the belt conveyance unit 23 with the normal route RC interposed therebetween. The region where the inkjet head unit 25 is disposed is a region smaller than the upper surface of the belt conveyance unit 23. The plurality of inkjet heads eject inks of different colors. As a result, an image is printed on the printing paper PA conveyed by the belt conveyance unit 23.

  The paper sensor 26 detects the printing paper PA conveyed from the registration roller 21 along the normal route RC, and outputs a detection signal to the control unit 9. The control unit 9 determines the feeding timing of the printing paper PA and the jamming of the printing paper PA based on the detection signal from the paper sensor 26. The sheet sensor 26 is disposed downstream of the registration roller 21 in the normal path RC. The paper sensor 26 can be an optical sensor having a light emitting element and a light receiving element.

  The paper sensor 27 detects the printing paper PA conveyed from the belt conveyance unit 23 along the normal route RC, and outputs a detection signal to the control unit 9. Based on the detection signal from the paper sensor 27, the control unit 9 determines the feeding timing of the printing paper PA and the jamming of the printing paper PA. The paper sensor 27 is disposed on the downstream side of the normal route RC from the belt conveyance unit 23. The paper sensor 27 can be an optical sensor having a light emitting element and a light receiving element.

  The ascending conveyance unit 4 conveys the printing paper PA printed by the lower conveyance printing unit 3 to the upper horizontal conveyance unit 5. The ascending conveyance unit 4 includes a plurality of pairs (for example, two pairs) of ascending conveyance rollers 28 and an ascending motor 29.

  The plurality of pairs of ascending conveyance rollers 28 are arranged at a predetermined interval along the normal path RC between the conveyance printing unit 3 and the horizontal conveyance unit 5. The normal route RC in the region where the ascending conveyance roller 28 is arranged is configured in a semicircular shape with an opening on the left side. All the ascending conveyance rollers 28 are rotationally driven by one ascending motor 29.

  The horizontal transport unit 5 transports the printing paper PA transported from the ascending transport unit 4 to the paper discharge unit 6 or the reversing unit 7. The horizontal conveyance unit 5 includes a plurality of pairs (for example, four pairs) of horizontal conveyance rollers 31, a horizontal motor 32, a switching unit 33, and a paper sensor (corresponding to a medium detection unit in claims) 34.

  The plurality of pairs of horizontal transport rollers 31 are arranged at a predetermined interval along the normal path RC between the ascending transport unit 4 and the paper discharge unit 6. The pair of horizontal transport rollers 31 are disposed in the upstream portion of the reversing path RR. All the horizontal conveyance rollers 31 are rotationally driven by one horizontal motor 32.

  The switching unit 33 switches the transport path of the printing paper PA between a paper discharge path RD connected to the paper discharge unit 6 and a reversing path RR connected to the reversing unit 7. The switching unit 33 is disposed at a branch point between the paper discharge route RD and the reversal route RR.

  The paper sensor 34 detects the printing paper PA conveyed to the switching unit 33 along the normal route RC and outputs a detection signal to the control unit 9. The control unit 9 determines the feeding timing of the printing paper PA and the jamming of the printing paper PA based on the detection signal from the paper sensor 34. The paper sensor 34 is disposed in the vicinity of the upstream side of the switching unit 33. The paper sensor 34 can be an optical sensor having a light emitting element and a light receiving element.

  The paper discharge unit 6 discharges and stacks printed printing paper PA. The paper discharge unit 6 includes a plurality of pairs of paper discharge rollers 41, a paper discharge motor 42, a paper discharge tray 43, and a paper sensor (corresponding to a medium detection unit in claims) 44.

  The paper discharge roller 41 discharges the printed printing paper PA conveyed from the horizontal conveyance unit 5 to the paper discharge tray 43. The plurality of pairs of paper discharge rollers 41 are disposed between the switching unit 33 and the paper discharge tray 43 along the paper discharge path RD. The paper discharge roller 41 is rotationally driven by a paper discharge motor 42.

  The paper discharge tray 43 is for stacking printed print paper PA discharged by the paper discharge roller. The paper discharge tray 43 is disposed at the downstream end of the paper discharge path RD. A part of the paper discharge tray 43 is exposed from the housing 10.

  The paper sensor 44 detects the printing paper PA discharged to the paper discharge tray 43 along the paper discharge path RD, and outputs a detection signal to the control unit 9. The control unit 9 determines the feeding timing of the printing paper PA and the jamming of the printing paper PA based on the detection signal from the paper sensor 44. The paper sensor 44 is disposed on the paper discharge path RD in the vicinity of the paper discharge tray 43. The paper sensor 44 can be an optical sensor having a light emitting element and a light receiving element.

  The reversing unit 7 reverses the printing paper PA that has been printed on one side during double-sided printing and re-feeds it to the transport printing unit 3. The reversing unit 7 includes a reversing roller 46, a reversing motor 47, a switchback unit 48, a refeed roller 49, a refeed motor 50, a flipper 51, and a paper sensor (corresponding to the medium detecting means in the claims). ) 52.

  The reversing roller 46 temporarily transports the print paper PA transported from the horizontal transport unit 5 to the switchback unit 48 and then transports it to the refeed roller 49. The reverse roller 46 is disposed between the most downstream horizontal transport roller 31 and the carry-in port of the switchback unit 48 on the reverse path RR. The reversing roller 46 is rotationally driven by a reversing motor 47 in the normal rotation direction (when carrying in) and the reverse direction (when carrying out).

  The switchback unit 48 is a space for the reversing roller 46 to temporarily carry the printing paper PA. The switchback unit 48 includes a space formed in the lower part of the paper discharge tray 43. The switchback portion 48 is opened in the vicinity of the reversing roller 46 for carrying the printing paper PA.

  The refeed roller 49 transports the printing paper PA transported from the reversing roller 46 to the registration roller 21 of the transport printing unit 3. The refeed roller 49 is disposed on the reverse path RR between the reverse roller 46 and the registration roller 21. The refeed roller 49 is rotated by a refeed motor 50.

  The flipper 51 guides the printing paper PA conveyed by the horizontal conveyance roller 31 to the reverse roller 46. Further, the flipper 51 guides the printing paper PA conveyed by the reversing roller 46 to the refeed roller 49. The flipper 51 is arranged in the vicinity of the center of gravity at three locations of the horizontal conveying roller 31, the reverse roller 46, and the refeed roller 49 on the most downstream side.

  The paper sensor 52 detects the printing paper PA conveyed while being guided by the flipper 51 along the reverse path RR, and outputs a detection signal to the control unit 9. Based on the detection signal from the paper sensor 52, the control unit 9 determines the feeding timing of the printing paper PA and the jamming of the printing paper PA. The sheet sensor 52 is disposed between the flipper 51 and the reverse roller 46. The paper sensor 52 can be an optical sensor having a light emitting element and a light receiving element.

  The input display unit 8 displays various images and information, and is used by the user to input information and instructions. The input display unit 8 is provided on the top of the housing 10. The input display unit 8 includes a touch panel and operation keys. The input display unit 8 is configured to allow a user to input a jam level Lvn (n = 1, 2,...) To be described later.

  Next, the control system of the duplex printing apparatus 1 will be described with reference to FIG.

  The control unit 9 is responsible for overall control of the duplex printing apparatus 1. That is, the control unit 9 controls the paper feeding unit 2, the conveyance printing unit 3, the ascending conveyance unit 4, the horizontal conveyance unit 5, the paper discharge unit 6, the reversing unit 7, and the input display unit 8. . As shown in FIG. 2, the control unit 9 stores a CPU (Central Processing Unit) 55 for executing various programs, a RAM (Random Access Memory) 56 for temporarily storing each information, a basic program, and the like. ROM (Read Only Memory) 57, a HDD (Hard Disk Drive) 58 in which a printing program, a paper feeding program, and the like are stored, and a connection unit 59 for input / output are provided. Yes.

  The HDD 58 stores a jam table shown in FIG. 3 in which the jam level Lvn and the paper sensors 26, 27, 34, 44, and 52 are associated with each other. In the initial value, it is assumed that the jam level Lv3 of the paper sensor 34 is the highest. The jam table also stores the number of jams Cntm (m = 1, 2,...) Of the paper sensors 26, 27, 34, 44, 52. Here, the jam occurrence number Cntm is incremented by “+1” every time a jam occurs. Then, the order of the jam level Lvn is set and changed in the order of the size of the jam occurrence number Cntm. Furthermore, the jam table is preferably created including elements such as paper size, paper thickness, and paper type.

  The HDD 58 stores a program for feeding printing paper when executing the normal mode, the interval mode, and the high-speed interval mode.

  The normal mode is a mode in which printing is performed while simultaneously transporting a plurality of print sheets PA on the transport path.

  In the interval mode, the control unit 9 uses the paper sensors 26, 27, 34, 44, and 52 with the highest jam level extracted from the jam table as paper feed determination sensors. In the single-sided printing in the interval mode, when the previous print paper PA is detected by the paper feed determination sensor, the control unit 9 controls the paper feed unit 2 to feed the next print paper PA. In the duplex printing in the interval mode, when the previous print paper PA is detected twice by the paper feed determination sensor, the control unit 9 controls the paper feed unit 2 to feed the next print paper PA.

  In the high-speed interval mode, the control unit 9 is the highest of the paper sensors 26, 27, 34, 44, 52 arranged upstream of the paper sensors 26, 27, 34, 44, 52 having the highest jam level Lvn. The paper sensors 26, 27, 34, 44, and 52 having a high jam level Lvn are set as paper feed determination sensors. In the single-sided printing in the high-speed interval mode, when the previous print paper PA is detected by the paper feed determination sensor, the control unit 9 controls the paper feed unit 2 to feed the next print paper PA. In double-sided printing in the high-speed interval mode, when the previous print paper PA is detected twice by the paper feed determination sensor, the control unit 9 controls the paper feed unit 2 to feed the next print paper PA.

  The HDD 58 stores an interval (hereinafter referred to as a sheet interval) between print sheets PA to be fed during single-sided printing in the normal mode. When performing single-sided printing, the control unit 9 feeds the printing paper PA based on the gap between the papers.

  The HDD 58 stores a paper spacing table for duplex printing in a normal mode in which paper spacing and paper length are associated with each other. The paper length is the length of the printing paper PA in the transport direction. When performing double-sided printing, the control unit 9 feeds the printing paper PA so that there is a paper gap based on the paper length. Note that the paper interval in double-sided printing is larger than the paper length.

  The HDD 58 stores a jam threshold that is a threshold of error between the detection signal input from each of the paper sensors 26, 27, 34, and 44 and the predicted time. The control unit 9 determines that a jam has occurred if the error is greater than or equal to the jam threshold. Further, the HDD 58 stores a jam threshold value for the normal mode and a jam threshold value for the interval mode and the high-speed interval mode. Here, the jam threshold value in the normal mode is smaller than the jam threshold value in the interval mode and the high-speed interval mode.

  The connection unit 59 is connected to the sheet feeding motors 14, 16, and 18 of the sheet feeding unit 2 so as to receive signals. Accordingly, the control unit 9 controls the paper feed motors 14, 16, and 18 to feed the printing paper PA from any one of the paper feed trays 11 and 12.

  The connection unit 59 is connected to the motors 22 and 24 of the transport printing unit 3 and the inkjet head unit 25 so as to be able to receive signals. Accordingly, the control unit 9 controls the motors 22 and 24 and the inkjet head unit 25 to print an image on the printing paper PA while conveying the printing paper PA. Further, the paper sensor 26, 27 of the transport printing unit 3 is connected to the connection unit 59 so that a detection signal can be transmitted. Thereby, the control unit 9 detects a jam of the printing paper PA in the vicinity of the belt conveyance unit 23 based on the detection signals from the paper sensors 26 and 27. Further, the control unit 9 controls the paper feed timing based on the detection signals from the paper sensors 26 and 27.

  The ascending motor 29 of the ascending conveyance unit 4 is connected to the connection unit 59 so as to receive a signal. Thereby, the control unit 9 conveys the printing paper PA to the horizontal conveyance unit 5 by controlling the raising motor 29.

  The horizontal motor 32 and the switching unit 33 of the horizontal conveyance unit 5 are connected to the connection unit 59 so as to be able to receive signals. Thus, the control unit 9 controls the horizontal motor 32 to convey the printing paper PA to the paper discharge unit 6 or the reversing unit 7. The paper sensor 34 of the horizontal conveyance unit 5 is connected to the connection unit 59 so that a detection signal can be transmitted. Thereby, the control unit 9 detects a jam of the printing paper PA near the switching unit 33 based on the detection signal from the paper sensor 34. Further, the control unit 9 controls the paper feed timing based on the detection signal from the paper sensor 34.

  A paper discharge motor 42 of the paper discharge unit 6 is connected to the connection unit 59 so as to receive a signal. As a result, the control unit 9 controls the paper discharge motor 42 to discharge the printed printing paper PA onto the paper discharge tray 43. A paper sensor 44 of the paper discharge unit 6 is connected to the connection unit 59 so that a signal can be transmitted. As a result, the control unit 9 counts the discharged print paper PA based on the detection signal transmitted from the paper sensor 44, and determines the completion of conveyance of the print paper PA and the completion of printing. Further, the control unit 9 detects a jam of the printing paper PA near the paper discharge tray 43 based on the detection signal transmitted from the paper sensor 44. Further, the control unit 9 controls the paper feed timing based on the detection signal from the paper sensor 43.

  Motors 47 and 50 of reversing unit 7 are connected to connecting unit 59 so as to be able to receive signals. The control unit 9 controls the motors 47 and 50 to invert the printing paper PA transported from the horizontal transport unit 5 and re-feeds it to the transport printing unit 3. The paper sensor 52 of the reversing unit 7 is connected to the connection unit 59 so that a detection signal can be transmitted. Accordingly, the control unit 9 detects a jam of the printing paper PA near the flipper 51 based on the detection signal from the paper sensor 52.

  The input display unit 8 is connected to the connection unit 59 so that signals can be transmitted and received. The control unit 9 can display various information on the input display unit 8. The control unit 9 receives various information input from the user via the input display unit 8. Information input by the user is change information of the jam level Lvn. Thereby, the control unit 9 rewrites the jam table of the HDD 58 by associating each paper sensor 26, 27, 34, 44, 52 with the changed jam level Lvn.

(Printing operation)
Next, the printing operation of the duplex printing apparatus 1 according to the first embodiment described above will be described. The printing operation will be described in parallel with the printing paper feed process executed by the control unit 9. FIG. 4 is a flowchart of the printing paper feeding process. FIG. 5 is a flowchart of single-sided paper feed processing in the normal mode. FIG. 6 is a flowchart of the duplex feeding process in the normal mode. FIG. 7 is a flowchart of single-sided paper feed processing in the interval mode. FIG. 8 is a flowchart of double-sided paper feed processing in the interval mode. FIG. 9 is a flowchart of single-sided paper feed processing in the high-speed interval mode. FIG. 10 is a flowchart of the duplex feeding process in the high-speed interval mode. The numbers after “S” shown in each flowchart indicate step numbers.

(Print paper feed processing)
First, when an instruction to start printing is input by the user, the control unit 9 determines the paper feed process selected by the user, as shown in FIG. Specifically, the control unit 9 determines whether or not the normal mode is set (S1).

  When determining that the normal mode is selected (S1: Yes), the control unit 9 determines whether or not the user has selected single-sided printing (S2).

  When the control unit 9 determines that the user's selection is single-sided printing (S2: Yes), the control unit 9 executes single-sided paper feeding processing and single-sided printing in the normal mode shown in FIG. 5 (S3). On the other hand, when the control unit 9 determines that the user's selection is not single-sided printing, that is, double-sided printing (S2: No), the control unit 9 executes the normal-mode double-sided paper feed processing and double-sided printing shown in FIG. 6 (S4). .

  When the control unit 9 determines in step S1 that the user's selection is not in the normal mode (S1: No), it determines whether or not the user's selection is in the interval mode (S5).

  If it determines with the interval mode (S5: Yes), the control part 9 will determine whether the user selected single-sided printing (S6).

  When determining that the user's selection is single-sided printing (S6: Yes), the control unit 9 executes single-sided paper feed processing and single-sided printing in the interval mode shown in FIG. 7 (S7). On the other hand, when the control unit 9 determines that the user's selection is not single-sided printing, that is, double-sided printing (S6: No), the control unit 9 executes the interval mode double-sided paper feed processing and double-sided printing shown in FIG. 8 (S8). .

  If the controller 9 determines that it is not the interval mode (S5: Yes), it executes the process of step S9. Here, neither the normal mode nor the interval mode means that the user's selection is the high-speed interval mode.

  Next, the control unit 9 determines whether or not the user has selected single-sided printing (S9).

  When determining that the user's selection is single-sided printing (S9: Yes), the control unit 9 executes single-sided paper feed processing and single-sided printing in the high-speed interval mode shown in FIG. 9 (S10). On the other hand, when the control unit 9 determines that the user's selection is not single-sided printing, that is, double-sided printing (S9: No), the control unit 9 executes double-sided paper feed processing and double-sided printing in the high-speed interval mode shown in FIG. 10 (S11). ).

  Thereafter, when any of the paper feed processes (S3, S4, S7, S8, S10, S11) is finished, the print paper feed process is finished.

(Single-sided printing in normal mode)
Next, single-sided printing and single-sided paper feed processing in the normal mode will be described with reference to FIG.

  First, in the single-sided paper feed process in the normal mode, as shown in FIG. 5, the control unit 9 sets a paper interval based on information stored in the HDD 58 (S21).

  Next, the control unit 9 controls any of the paper feed rollers 13, 15, and 17 of the paper feed unit 2 to transfer the printing paper PA from any of the paper feed bases 11 and 12 to the transport printing unit 3. Paper is fed along the paper feed path RS (S22).

  Next, the control unit 9 determines whether or not a jam has occurred based on information from each of the paper sensors 26, 27, 34, and 44 (S23). The control unit 9 determines the occurrence of a jam based on whether or not an error between the time when the detection signal is input from each of the paper sensors 26, 27, 34, and 44 and the predicted time exceeds a jam threshold. If the control unit 9 determines that a jam has not occurred (S23: Yes), the control unit 9 executes the process of S24.

  Based on the detection signal from the paper sensor 26, the control unit 9 sets the interval between the trailing edge of the previously fed printing paper PA and the leading edge of the printing paper PA to be fed from now on. It is determined whether or not it is the paper feed timing (S24). The controller 9 repeats steps S23 and S24 until it is determined that the paper feed timing has come (S24: No).

  Next, when it is determined that the paper feeding timing has come (S24: Yes), the control unit 9 determines whether or not a predetermined number of printing papers PA have been fed (S25).

  When the control unit 9 determines that the predetermined number of print sheets PA has not been fed (S25: No), the control unit 9 returns to step S22 and feeds the next print sheet PA. Thereafter, the control unit 9 repeats steps S22 to S25 until a predetermined number of sheets of printing paper PA are fed (S25: Yes). Thereby, in the normal mode, the printing paper PA is sequentially fed between the set papers. That is, a plurality of print sheets PA are simultaneously transported on the transport path.

  On the other hand, the fed printing paper PA is conveyed by the registration roller 21 to the belt conveyance unit 23 in the conveyance printing unit 3. Next, an image is printed on the printing paper PA by the ink ejected from the inkjet head of the inkjet head unit 25 while being conveyed by the belt conveyance unit 23. After printing, the printing paper PA is conveyed by the belt conveyance unit 23 to the ascending conveyance unit 4 along the normal route RC in the right direction. In the ascending conveyance unit 4, the printing paper PA is conveyed to the upper horizontal conveyance unit 5 by the ascending conveyance roller 28 along the semicircular normal path RC. In the horizontal conveyance unit 5, the printing paper PA is conveyed leftward by the horizontal conveyance roller 31.

  Next, the printing paper PA is guided by the switching unit 33 and conveyed to the paper discharge unit 6. In the paper discharge unit 6, the print paper PA is transported along the paper discharge path RD by the paper discharge roller 41 and discharged onto the paper discharge tray 43.

  Thereafter, when the control unit 9 determines that a predetermined number of printing sheets PA have been fed (S25: Yes), the single-sided feeding process in the normal mode is terminated.

  On the other hand, if the control unit 9 determines that a jam has occurred before the feeding and printing of the predetermined number of print sheets PA are completed (S23: Yes), the jam count process is executed (S26). In the jam count process, the control unit 9 increments the jam occurrence number Cntm of the paper sensors 26, 27, 34, and 44 where the jam occurs by “+1”. Thereafter, the control unit 9 ends the single-sided paper feeding process in the normal mode.

(Double-sided printing in normal mode)
Next, double-sided printing and double-sided paper feed processing in the normal mode will be described with reference to FIG. A process similar to the above-described paper feed process will be described in a simplified manner.

  First, in the duplex feeding process in the normal mode, as shown in FIG. 6, the control unit 9 extracts the sheet interval corresponding to the sheet length of the image data from the sheet interval table stored in the HDD 58 (S 31). .

  Next, the control unit 9 controls the paper feeding unit 2 to feed the printing paper PA (S32). Thereafter, the control unit 9 repeats the determination of the occurrence of a jam (S33: No) and the determination of the paper feed timing (S34) until the paper feed timing corresponding to the interval between sheets is reached. When the control unit 9 determines that it is the paper feed timing (S34: Yes), it determines whether or not a predetermined number of printing papers PA have been fed (S35). If the control unit 9 determines that the predetermined number of printing papers PA is not fed (S35: No), the control unit 9 returns to step S32 and feeds the next printing paper PA (S32). Thereafter, the control unit 9 repeats steps S32 to S35 until a predetermined number of sheets of printing paper PA are fed (S35: Yes). Thereby, in the normal mode, the printing paper PA is sequentially fed between the set papers. That is, a plurality of print sheets PA are simultaneously transported on the transport path.

  On the other hand, the fed printing paper PA is conveyed to the ascending conveyance unit 4 while being printed by the conveyance printing unit 3. Thereafter, the printing paper PA is conveyed by the ascending conveyance unit 4 and the horizontal conveyance unit 5 and then guided to the reversing unit 7 by the switching unit 33. In the reversing unit 7, the printing paper PA is temporarily carried into the switchback unit 48 by the reversing roller 46, and then conveyed to the refeed roller 49 by the reversing roller 46. Thereafter, the printing paper PA is fed again by the refeed roller 49 to the registration roller 21 of the transport printing unit 3. Here, the gap between the fed printing paper PA and the printing paper PA is longer than the paper length of the printing paper PA. The re-printed printing paper PA is disposed between the fed printing paper PA and the printing paper PA. As a result, the re-fed printing paper PA that has been printed on one side and the fed printing paper PA that has not been printed are alternately conveyed from the registration roller 21 to the belt conveyance unit 23. Thereafter, an image is printed on the non-printed surface of the re-fed printing paper PA by the inkjet head unit 25. The printing paper PA that has been printed on both sides is conveyed by the ascending conveyance unit 4 and the horizontal conveyance unit 5 and then discharged by the paper discharge unit 6 onto the paper discharge tray 43.

  On the other hand, when the control unit 9 determines that a predetermined number of printing sheets PA have been fed (S35: Yes), the duplex feeding process in the normal mode is terminated.

  If the control unit 9 determines that a jam has occurred according to the detection signals from the paper sensors 26, 27, 34, 44, and 52 before feeding the predetermined number of printing papers PA (S33: Yes), the step After executing the same jam count process as S26 (S36), the double-sided paper feed process in the normal mode is terminated.

(Single-sided printing in interval mode)
Next, single-sided printing and single-sided paper feed processing in the interval mode will be described with reference to FIG. A process similar to the above-described paper feed process will be described in a simplified manner.

  First, in the single-sided paper feed process in the interval mode, as shown in FIG. 7, the control unit 9 selects a paper feed determination sensor based on the jam table shown in FIG. 3 (S41). Here, the paper sensor 26, 27, 34, 44 having the highest jam occurrence number Cntm and the highest jam level Lvn is selected as the paper feed determination sensor. In the following description, it is assumed that the control unit 9 selects the paper sensor 34 as the paper feed determination sensor.

  Next, the control unit 9 feeds the printing paper PA (S42). Thereafter, the fed printing paper PA is conveyed to the ascending conveyance unit 4 while being printed by the conveyance printing unit 3. Thereafter, the printing paper PA is conveyed by the ascending conveyance unit 4 and the horizontal conveyance unit 5.

  During the conveyance, the controller 9 determines whether or not a jam has occurred based on the detection signals from the respective paper sensors 26, 27, 34, and 44 (S43). The control unit 9 determines that a jam has occurred when the error between the detection signal input from each of the paper sensors 26, 27, 34, and 44 and the predicted time exceeds the jam threshold. Here, the jam threshold in the interval mode is larger than the jam threshold in the normal mode. That is, the criterion for determining the jam in the interval mode is lower than the criterion for determining the jam in the normal mode. If it is determined that a jam has not occurred (S43: No), the controller 9 determines whether or not the print paper PA has been detected by the paper sensor 34, which is a paper feed determination sensor (S44).

  When the detection signal from the paper sensor 34 which is a paper feed determination sensor is not input to the control unit 9, the control unit 9 determines that the print paper PA is not detected by the paper sensor 34 (S44: No). Return to step S43. Thereafter, the control unit 9 repeats steps S43 and S44 until the printing paper PA is detected by the paper sensor 34.

  On the other hand, when the printing paper PA reaches the vicinity of the switching unit 33 of the horizontal conveyance unit 5 and is detected by the paper sensor 34, the paper sensor 34 outputs a detection signal to the control unit 9. Accordingly, the control unit 9 determines that the printing paper PA has been detected by the paper sensor 34 (S44: Yes), and determines whether or not a predetermined number of printing papers PA has been fed (S45).

  When the control unit 9 determines that the predetermined number of printing papers PA is not fed (S45: No), the control unit 9 controls the paper feeding unit 2 to feed the next printing paper PA ( S42).

  Thereafter, the previously fed printing paper PA is discharged to the paper discharge tray 43 of the paper discharge unit 6.

  On the other hand, if the control unit 9 determines that a predetermined number of printing sheets PA have been fed after repeating Steps S42 to S45 (S45: Yes), the single-sided feeding process in the interval mode is terminated.

  If the control unit 9 determines that a jam has occurred before feeding the predetermined number of print sheets PA (S43: Yes), the control unit 9 executes a jam count process similar to step S26 (S46), and then performs an interval. The single-sided paper feed processing in the mode is finished.

(Double-sided printing in interval mode)
Next, double-sided printing and double-sided paper feed processing in the interval mode will be described with reference to FIG. A process similar to the above-described paper feed process will be described in a simplified manner.

  First, in the double-side paper feed process in the interval mode, as shown in FIG. 8, the control unit 9 selects a paper feed determination sensor based on the jam table shown in FIG. 3 (S51). Here, the paper sensor 26, 27, 34, 44, 52 having the highest jam level Lvn is selected as the paper feed determination sensor. In the following description, it is assumed that the control unit 9 selects the paper sensor 34 as the paper feed determination sensor.

  Next, the control unit 9 feeds the printing paper PA (S52). Thereafter, the fed printing paper PA is conveyed to the ascending conveyance unit 4 while being printed by the conveyance printing unit 3. Thereafter, the printing paper PA is conveyed by the ascending conveyance unit 4 and the horizontal conveyance unit 5. Here, when the printing paper PA is detected by the paper sensor 34, the paper sensor 34 outputs a detection signal to the control unit 9. Thereby, the control unit 9 stores the printing paper PA detected once by the paper sensor 34. Thereafter, the printing paper PA is fed again from the horizontal conveyance unit 5 to the conveyance printing unit 3 via the reversing unit 7. Next, the printing paper PA is transported by the ascending transport unit 4 and the horizontal transport unit 5 after an image is printed on the unprinted surface by the transport printing unit 3.

  During the conveyance, the control unit 9 determines whether or not a jam has occurred based on the detection signals from the respective paper sensors 26, 27, 34, 44, and 52 (S53). If it is determined that a jam has not occurred (S53: No), the controller 9 determines whether or not the print paper PA has been detected twice by the paper sensor 34, which is a paper feed determination sensor (S54). Thereafter, the control unit 9 repeats steps S53 and S54 until the printing paper PA is detected twice by the paper sensor 34 (S54: No). The number of detections (= 2 times) described above is an example, and the number of detections can be changed as appropriate depending on the installation position of the paper sensor. For example, when the paper sensor 44 is a paper feed determination sensor, the number of detections is one.

  On the other hand, after the printing paper PA is printed on both sides, when the paper sensor 34 detects the printing paper PA twice, the paper sensor 34 serving as a paper feed determination sensor outputs a second detection signal to the control unit 9. Accordingly, the control unit 9 determines that the printing paper PA has been detected twice by the paper sensor 34 (S54: Yes), and determines whether or not a predetermined number of printing papers PA has been fed (S55).

  When the control unit 9 determines that the predetermined number of printing papers PA is not fed (S55: No), the control unit 9 controls the paper feeding unit 2 to feed the next printing paper PA ( S52).

  Thereafter, the printing paper PA that has been fed first and on which images have already been printed on both sides is ejected to the paper ejection tray 43 of the paper ejection unit 6.

  On the other hand, if the control unit 9 repeats steps S52 to S55 and determines that a predetermined number of print sheets PA have been fed (S55: Yes), the duplex feeding process in the interval mode is terminated.

  If the control unit 9 determines that a jam has occurred before feeding the predetermined number of print sheets PA (S53: Yes), the control unit 9 executes the jam count process similar to step S26 (S56), and then performs an interval. The duplex paper feed process in the mode is terminated.

(Single-sided printing in high-speed interval mode)
Next, single-sided printing and single-sided paper feed processing in the high-speed interval mode will be described with reference to FIG. A process similar to the above-described paper feed process will be described in a simplified manner.

  First, in the single-sided paper feed process in the high-speed interval mode, as shown in FIG. 9, the control unit 9 selects a paper feed determination sensor based on the jam table shown in FIG. 3 (S61). Here, the paper feed determination sensor is the paper sensor 26 having the highest jam level Lvn among the paper sensors 26, 27, 34, 44 on the upstream side of the paper sensors 26, 27, 34, 44 having the highest jam level Lvn. 27, 34, 44 are selected. In the following description, it is assumed that the control unit 9 selects the paper sensor 27 as the paper feed determination sensor.

  Next, the control unit 9 feeds the printing paper PA (S62). Thereafter, the fed printing paper PA is conveyed to the ascending conveyance unit 4 while being printed by the conveyance printing unit 3.

  During the conveyance, the controller 9 determines whether or not a jam has occurred based on the detection signals from the paper sensors 26, 27, 34, and 44 (S63). If it is determined that a jam has not occurred (S63: No), the controller 9 determines whether or not the print paper PA has been detected by the paper sensor 27, which is a paper feed determination sensor (S64).

  When the detection signal from the paper sensor 27 which is a paper feed determination sensor is not input to the control unit 9, the control unit 9 determines that the print paper PA is not detected by the paper sensor 27 (S64: No). Returning to step S63, steps S63 and S64 are repeated.

  On the other hand, when the printing paper PA reaches the vicinity of the ascending conveyance unit 4 and is detected by the paper sensor 27, the paper sensor 27 outputs a detection signal to the control unit 9. Accordingly, the control unit 9 determines that the print sheet PA has been detected by the sheet sensor 27 (S64: Yes), and determines whether or not a predetermined number of print sheets PA have been fed (S65).

  When the control unit 9 determines that the predetermined number of print sheets PA has not been fed (S65: No), the control unit 9 controls the paper feed unit 2 to feed the next print sheet PA (S62). ). In other words, when the printing paper PA is detected by the paper sensor 27 upstream of the paper sensor 34, the control unit 9 feeds the next printing paper PA. Thereby, in the high-speed interval mode, the paper feed interval of the printing paper PA becomes shorter than in the interval mode, and the number of printed sheets per unit time increases. As a result, productivity is improved.

  Thereafter, the previously fed printing paper PA is transported by the ascending transport unit 4 and the horizontal transport unit 5, and then discharged onto the paper discharge tray 43 of the paper discharge unit 6.

  On the other hand, when the control unit 9 repeats steps S62 to S65 and determines that a predetermined number of printing sheets PA have been fed (S65: Yes), the single-sided feeding process in the high-speed interval mode is terminated.

  If the control unit 9 determines that a jam has occurred before feeding the predetermined number of print sheets PA (S63: Yes), the control unit 9 executes a jam count process similar to step S26 (S66), and then End the single-sided paper feed processing in the interval mode.

(Double-sided printing in high-speed interval mode)
Next, double-sided printing and double-sided paper feed processing in the high-speed interval mode will be described with reference to FIG. A process similar to the above-described paper feed process will be described in a simplified manner.

  First, in double-sided paper feed processing in the high-speed interval mode, as shown in FIG. 10, the control unit 9 selects a paper feed determination sensor based on the jam table shown in FIG. 3 (S71). Here, the paper feed determination sensor has the highest jam level Lvn among the paper sensors 26, 27, 34, 44, 52 upstream of the paper sensors 26, 27, 34, 44, 52 with the highest jam level Lvn. Paper sensors 26, 27, 34, 44, and 52 are selected. In the following description, it is assumed that the control unit 9 selects the paper sensor 27 as the paper feed determination sensor.

  Next, the control unit 9 feeds the printing paper PA (S72). Thereafter, the fed printing paper PA is conveyed to the ascending conveyance unit 4 while being printed by the conveyance printing unit 3. Here, when the printing paper PA is detected by the paper sensor 27, the paper sensor 27 outputs a detection signal to the control unit 9. Thereby, the control unit 9 stores the printing paper PA detected once by the paper sensor 27. Thereafter, the printing paper PA is conveyed from the ascending conveyance unit 4 and the horizontal conveyance unit 5 to the conveyance printing unit 3 via the reversing unit 7. Next, the printing paper PA is conveyed to the ascending conveyance unit 4 after an image is printed on the unprinted surface by the conveyance printing unit 3.

  During the conveyance, the control unit 9 determines whether or not a jam has occurred based on the detection signals from the respective paper sensors 26, 27, 34, 44, and 52 (S73). If the control unit 9 determines that a jam has not occurred (S73: No), the control unit 9 determines whether the print paper PA has been detected twice by the paper sensor 27, which is a paper feed determination sensor (S74).

  Thereafter, the control unit 9 repeats steps S73 and S74 until the printing paper PA is detected twice by the paper sensor 27 (S74: No).

  On the other hand, the print paper PA is detected twice by the paper sensor 27, and the paper sensor 27, which is a paper feed determination sensor, outputs a second detection signal to the control unit 9. Accordingly, the control unit 9 determines that the printing paper PA has been detected twice by the paper sensor 27 (S74: Yes), and determines whether or not a predetermined number of printing papers PA has been fed (S75).

  When the control unit 9 determines that the predetermined number of printing papers PA is not fed (S75: No), the control unit 9 controls the paper feeding unit 2 to feed the next printing paper PA ( S72). In other words, when the printing paper PA is detected by the paper sensor 27 upstream of the paper sensor 34, the control unit 9 feeds the next printing paper PA. This shortens the paper feed interval of the print paper PA and increases the number of printed sheets per unit time.

  Thereafter, the printing paper PA that has been fed first and on which images have already been printed on both sides is ejected to the paper ejection tray 43 of the paper ejection unit 6.

  On the other hand, when the control unit 9 repeats steps S72 to S75 and determines that a predetermined number of printing sheets PA have been fed (S75: Yes), the duplex feeding process in the high-speed interval mode is terminated.

  If the control unit 9 determines that a jam has occurred before feeding the predetermined number of print sheets PA (S73: Yes), the control unit 9 executes a jam count process similar to step S26 (S76), and then performs a high-speed operation. The double-sided paper feed process in the interval mode is terminated.

(Jam level change processing)
Next, a jam level changing process for the user to change the jam level using the input display unit 8 will be described with reference to the drawings. FIG. 11 is a flowchart of the jam level changing process.

  As shown in FIG. 11, in the jam level changing process, first, the control unit 9 displays a jam level changing screen on the input display unit 8 (S81). The jam level change screen here is a screen in which the jam level Lvn and the arrangement positions of the paper sensors 26, 27, 34, 44, 52 are associated with each other.

  Next, the control unit 9 determines whether or not the user has selected the placement location of the paper sensors 26, 27, 34, 44, and 52 (S82). The control unit 9 repeats step S82 until the user inputs an arrangement location.

  If the control unit 9 determines that the user has selected and input the placement location (S82: Yes), the jam level Lvn of the paper sensors 26, 27, 34, 44, 52 corresponding to the placement location is changed to the maximum value. (S83). As an example, when the user wants to perform printing while confirming the alignment of the printed printing paper PA discharged to the paper discharge tray 43, the user selects an arrangement location near the paper discharge tray 43. . Thereby, the control unit 9 sets the jam level Lv4 of the paper sensor 44 to the maximum value.

  Thereafter, the control unit 9 rewrites the jam table of the HDD 58 based on the changed jam level Lvn (S84).

  Thereby, the jam level changing process is completed.

  Thereafter, when the user selects the interval mode and executes printing, the paper sensors 26, 27, 34, 44, and 52 whose jam level Lvn has been changed to the maximum value by the user function as a paper feed determination sensor.

(Effect of 1st Embodiment)
Next, effects of the double-sided printing apparatus 1 according to the first embodiment described above will be described.

  As described above, in the double-sided printing device 1 according to the first embodiment, the control unit 9 uses the paper sensors 26, 27, 34, 44, and 52 having the highest jam level Lvn set based on the jam occurrence number Cntm. When the printing paper PA is detected, an interval mode for feeding the next printing paper PA is provided. As a result, it is possible to shorten the time until the printing is completed by increasing the number of printed sheets per unit time while reducing the damage when the jam occurs. In particular, this embodiment is effective when printing is performed using high-quality paper or the like. Furthermore, this embodiment is particularly effective when the conveyance path is long.

  Further, the duplex printing apparatus 1 is configured such that the user can change the jam level Lvn by the input display unit 8. Thereby, the duplex printing apparatus 1 can flexibly cope with a user's desire to change the paper feed timing. For example, when the user wants to execute printing while confirming the alignment of the printed printing paper PA discharged to the paper discharge tray 43, the user realizes it by maximizing the jam level Lv4 of the paper sensor 44. it can.

  Further, in the duplex printing apparatus 1, the control unit 9 has a high-speed interval mode in which the paper sensors 26, 27, 34, 44, and 52 upstream of the interval mode are selected as the paper feed determination sensor. Thereby, the double-sided printing apparatus 1 can cope with the case where the user prioritizes the increase in the printing speed over the jam damage.

  Further, in the duplex printing apparatus 1, the controller 9 is configured to feed the next printing paper PA when the previous printing paper PA is detected twice by the paper feed determination sensor in the interval mode duplex printing. Has been. Thereby, the duplex printing apparatus 1 can further reduce jam damage by duplex printing.

  As mentioned above, although this invention was demonstrated in detail using embodiment, this invention is not limited to embodiment described in this specification. The scope of the present invention is determined by the description of the claims and the scope equivalent to the description of the claims. Hereinafter, modified embodiments in which the above-described embodiment is partially modified will be described.

  The arrangement, shape, numerical value, and the like of the configuration of the above-described embodiment can be changed as appropriate. Moreover, each process of embodiment mentioned above can be changed suitably.

  The medium detection means (paper sensor) has a light receiving / shielding sensor that turns off the detection signal when the print medium passes, or the detection signal turns on when the print medium passes. A reflective sensor or the like can be applied.

  As a jam detection method, it is determined whether the print medium is normal or jammed depending on the length in the conveyance direction of the print medium calculated from the leading edge and the trailing edge of one printing medium (printing paper) detected by the medium detecting means (paper sensor). A determination method can be applied. As another jam detection method, there is a method for determining whether the jam is normal or jammed based on the interval between two print media calculated from the rear end of the previous print medium and the front end of the next print medium detected by the medium detection means. Applicable. Furthermore, as another jam detection method, the length of the print medium and the interval between the print media, that is, the time when the leading edge of the previous print medium is detected by the upstream medium detection means within a predetermined time from the downstream side. A method of determining whether the jam is normal or jammed by detecting the leading edge of the next print medium by the medium detecting means can be applied.

  Further, as a jam detection method, a jam that the medium detection unit changes from a state in which no print medium is detected to a state in which a print medium is detected by conveying the print medium within a predetermined time. By detecting the detection method (unreached jam detection) or transporting the print medium, the medium detection means changes from a state in which the print medium is detected to a state in which the print medium is not detected within a predetermined time. It is possible to apply a method such as a jam detection method (residual jam detection).

  In the detection method of the print medium (printing paper) by the medium detection means (paper sensor), the threshold value is set for the ON state duration in consideration of the case where the detection signal from the medium detection means results in an error that does not change from the ON state to the OFF state. An error may be determined by providing

  In the above-described embodiment, the user can select any one of the normal mode, the interval mode, and the high-speed interval mode. However, the present invention is not limited to this. For example, the present invention may be applied to a self-learning type printing apparatus having no mode. Specifically, the paper feed process may be configured only by the above-described interval mode, and the control unit may be configured to select the paper feed determination sensor according to the number of jam detections.

DESCRIPTION OF SYMBOLS 1 Duplex printing apparatus 2 Paper feed part 3 Conveyance printing part 4 Ascending conveyance part 5 Horizontal conveyance part 6 Paper discharge part 7 Inversion part 8 Input display part 9 Control part 10 Case 11 Side paper feed tray 12 Internal paper feed stand 13 Side feed Paper roller 14 Side paper feed motor 15 Internal paper feed roller 16 Internal paper feed motor 17 Merge paper feed roller 18 Merge paper feed motor 21 Registration roller 22 Registration motor 23 Belt transport unit 24 Belt motor 25 Inkjet head units 26 and 27 Paper sensor 33 Switching unit 34, 44, 52 Paper sensor Lvn Jam level Cntm Number of jams PA Printing paper RC Normal path RD Paper discharge path RR Reverse path RS Paper feed path

Claims (4)

A paper feeder for feeding print media;
A plurality of medium detection means for detecting a print medium conveyed along the conveyance path and outputting a detection signal;
A control unit for controlling the paper feeding unit to feed the print medium and detecting a jam of the print medium based on a detection signal input from the medium detection unit;
The control unit stores a jam table in which a jam level of the medium detection unit is set based on the number of jam occurrences, and determines that a print medium is detected by the medium detection unit having the highest jam level. A printing apparatus that controls a paper feed unit to feed a next print medium. It further comprises an input means for inputting a jam level change,
The printing apparatus according to claim 1, wherein the control unit rewrites a jam table according to a jam level changed by the input unit.   When the print medium is detected by the medium detection unit having the highest jam level among the medium detection units arranged upstream of the medium detection unit having the highest jam level, the control unit performs the paper feeding. The printing apparatus according to claim 1, wherein the next printing medium is fed by controlling the printing unit.   When the control unit determines that the print medium has been detected a predetermined number of times by the medium detection unit having the highest jam level when performing double-sided printing, the control unit controls the paper supply unit to feed the next print medium. The printing apparatus according to claim 1, wherein the printing apparatus is a printing apparatus.