JP2012091361A - Printing apparatus and its control method - Google Patents

Abstract

In a printing apparatus that prints an image by scanning a carriage with respect to a recording medium to be conveyed, a technique capable of more accurately detecting a jam at the time of conveyance is provided.
Before executing printing on a sheet, the sheet is conveyed to a predetermined jam detection position (step S301), and during this time, whether or not there is a load variation of a load variation with respect to a motor that drives a conveyance roller that conveys the sheet. Then, a jam caused by contact between the carriage and the sheet is detected (step S302). When a load change is detected, the sheet is discharged to the rear side (feed tray side) (S311). If no load change is detected, the sheet is returned to the print start position (step S303), and a normal printing operation is performed. Do.
[Selection] Figure 6

Description

  The present invention relates to a printing apparatus that prints an image by applying a recording agent from a carriage that scans and moves on a recording medium that is transported along a predetermined transport path, and a control method therefor.

  In a printing apparatus that prints an image on a recording medium transported along a transport path, a so-called jam in which the recording medium leaves the transport path and becomes jammed due to, for example, warping or bending of the recording medium. Various techniques have been proposed for detecting jams at an early stage. For example, in the technique described in Patent Document 1, a change in carriage load is detected to detect a jam caused by contact between a carriage having a recording head that reciprocates in a main scanning direction orthogonal to the conveyance direction of the recording medium and the recording medium. We are using. Specifically, the carriage drive current value is monitored, and if the value exceeds a predetermined threshold, it is determined that a jam has occurred.

Japanese Patent Laying-Open No. 2005-178268 (for example, FIG. 5)

  In this type of printing device, the size and thickness of the recording medium to be used are specified. However, a recording medium that is not suitable for the printing device may be used by mistake, and jams caused by this may be a problem. It has become. For example, in a device that is particularly downsized, it may be difficult to have a structure that can easily expose the conveyance path of the recording medium, and when a jam occurs, it takes time to take out the recording medium jammed inside the apparatus. May take. From this point of view, the necessity of early and accurate detection of jam is increasing.

  However, in the above-described conventional jam detection technology, jam detection is performed by detecting a load fluctuation in the scanning movement of the carriage for printing an image on a recording medium. Therefore, jam detection is performed until actual printing is performed. Could not do. As a result, when the jam is detected, contact between the recording medium and the carriage has already occurred, and there are cases where it is impossible to avoid problems such as damage to the recording medium or damage to the carriage. Further, there is a problem that the recording material consumed in the printing operation until the jam is detected is wasted.

  According to some aspects of the present invention, in a printing apparatus that prints an image by scanning and moving a carriage with respect to a recording medium to be conveyed, the above-described problem can be solved and a jam at the time of conveyance can be detected more accurately. The technology that can be provided.

  In order to solve the above-described problems, a printing apparatus according to the present invention includes a conveyance mechanism that feeds a recording medium toward a printing position along a predetermined conveyance path, and a carriage that is disposed to face the recording medium that is fed to the printing position. And a drive unit that scans and moves the carriage in a main scanning direction different from the conveyance direction of the recording medium along the conveyance path, and applies a recording agent from the carriage to the recording medium to the recording medium. A printing unit that prints an image, and before the printing by the printing unit, the conveyance mechanism conveys the recording medium so that the leading end portion of the recording medium in the conveyance direction exceeds the printing position. And a control means for performing a pre-printing jam detection operation for detecting a jam of the recording medium in the conveyance path in between.

  Also, the control method of the printing apparatus according to the present invention is such that a recording medium is fed toward a printing position along a predetermined conveyance path by a conveyance mechanism, and the recording medium is sent to the recording medium fed to the printing position. A printing apparatus control method for printing an image on the recording medium by applying a recording agent from a carriage that scans and moves in a main scanning direction that is different from the conveyance direction of the recording medium. Pre-print jam detection operation for transporting the recording medium by a transport mechanism, causing the leading end of the recording medium in the transport direction to pass the print position, and detecting a jam of the recording medium in the transport path during the transport It is characterized by performing.

  In these inventions, the recording medium is once sent to the conveyance path before the start of printing accompanied by the scanning movement of the carriage, and the leading end in the conveyance direction passes through the printing position. If the recording medium has a cause of jam such as curling, bending, thickness difference, etc., jam occurs at a high probability at this point, while if jam does not occur at this time, it is also conveyed in the subsequent printing operation. There is a high probability of being able to do it properly. Therefore, it is possible to detect in advance a jam that may occur in subsequent printing by conveying the recording medium beyond the printing position and detecting whether or not a jam has occurred during this time. Thereby, it is possible to avoid problems such as damage to the recording medium and apparatus due to the occurrence of jam during printing, wasteful consumption of the recording agent, and the like.

  In the present invention, when a jam is not detected in the pre-printing jam detection operation, it is desirable to move the recording medium to a position where printing is started on the recording medium and print an image on the recording medium. . As a result, printing is performed on a recording medium that has been actually transported and does not cause jamming until the printing position is once exceeded, so that the probability of jamming during printing can be greatly reduced.

  Further, when the printing apparatus includes a discharge mechanism that discharges the recording medium that has passed the printing position along the conveyance path, in the pre-printing jam detection operation, the conveyance distance of the leading end of the recording medium from the printing position is set. You may make it be more than the length of the conveyance path | route from a printing position to a discharge mechanism. In this case, if the recording medium is properly transported along the transport path, the leading end portion should reach the discharge mechanism. Therefore, if no jam occurs during this time, the recording medium can be discharged out of the apparatus by the discharge mechanism. It is possible to predict whether or not the recording medium can be properly discharged in the printing operation by conveying the recording medium in advance to a position where it can be discharged to the outside of the apparatus in this way in the jam detection operation before printing, In particular, it is possible to prevent the recording medium from being jammed inside the apparatus and being unable to be taken out.

  In order to obtain the above effect, in principle, the conveyance distance of the leading end of the recording medium from the printing position in the pre-printing jam detection operation should be equal to the length of the conveyance path from the printing position to the discharge mechanism. However, in an actual apparatus, it is preferable that some warping of the recording medium on the transport path is allowed to be warped. To cope with such a case, the transport distance of the recording medium is set to the printing position. It is desirable that the length is slightly longer than the length of the transport path from the to the discharge mechanism.

  In the jam detection operation, for example, a jam of the recording medium can be detected based on the magnitude of a load applied to the transport mechanism as the recording medium is transported. If a jam of the recording medium occurs in the transport path, it is considered that the load applied to the transport mechanism is greatly changed compared to the normal time. Therefore, it is possible to detect the presence or absence of a jam from the magnitude of the load applied to the transport mechanism. With such a jam detection technique, it is possible to perform a pre-print jam detection operation without damaging the transported recording medium.

  In the jam detection operation, it is also possible to detect a jam of the recording medium based on a physical quantity that changes due to, for example, driving of the carriage by the drive unit. If the recording medium has a jam generation factor such as warping or bending, the carriage comes into contact with the carriage during the scanning movement, and this can be detected as a change in physical quantity accompanying the movement of the carriage.

  For example, it is possible to detect the presence or absence of a jam based on the detection result by using at least one of the driving torque of the carriage by the driving unit, the energy amount consumed by the driving unit, and the moving speed of the carriage as the physical quantity described above. Each of these physical quantities is a physical quantity that can take values that differ greatly when the carriage moves without contacting the recording medium and when the movement of the carriage is inhibited by contact with the recording medium. Therefore, these physical quantities can be suitably used for jam detection in the present invention.

  In addition, for example, when a continuous print job for printing an image on a plurality of recording media is executed, the continuous printing job is performed before printing on a part of the recording media including the first one of the plurality of recording media. A pre-printing jam detection operation may be executed. In a normal use mode, since a plurality of recording media prepared for printing are the same type, it is difficult to think that the probability of occurrence of jam varies greatly from one sheet to another. Therefore, it is considered that it is not always necessary to perform the pre-print jam detection operation for all the recording media. Further, when a plurality of recording media prepared have a jam generation factor such as a difference in size, the jam should occur from the first sheet. In this sense, if the pre-printing jam detection operation is performed for only a part of the plurality of recording media including at least the first one, jamming in the subsequent recording media is prevented and each recording medium is prevented. The printing throughput can be improved as compared with the case where the pre-printing jam detection operation is performed.

  When executing a single-leaf print job for printing an image on a single recording medium, the single-leaf print job selects printing with a jam detection operation before printing and printing without a jam detection operation before printing. It may be possible to execute automatically. As a case where printing is performed on only one recording medium, test printing for confirming the finish, layout, and the like before performing regular printing can be considered. In such a case, a different type of recording medium from the regular recording medium may be used, so it is desirable to perform a pre-printing jam detection operation. On the other hand, only one sheet may be printed on a regular recording medium. By making it possible to select printing with a pre-printing jam detection operation and printing without a pre-printing jam detection operation, both of these cases can be handled.

1 is a diagram showing a main part of a photo printer as one embodiment of the present invention. FIG. 2 is a block diagram showing an electrical configuration of the photo printer of FIG. 1. 2 is a flowchart showing a printing operation in the photo printer of FIG. 1. The figure which shows typically the mode of the paper conveyance in printing operation. 6 is a flowchart showing a paper jam discharging operation. 5 is a flowchart illustrating a first embodiment of a pre-printing jam detection operation. FIG. 6 is a diagram illustrating a paper position on a conveyance path in a pre-printing jam detection operation. FIG. 4 is a diagram illustrating an example of the posture of a sheet on a conveyance path. 9 is a flowchart illustrating a second embodiment of a pre-printing jam detection operation. 6 is a flowchart showing start-up processing in this photo printer.

  FIG. 1 is a diagram showing a main part of a photo printer as an embodiment of a printing apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the photo printer of FIG. For convenience of the following description, the X, Y and Z coordinate axis directions are defined as shown in FIG.

  The photo printer 1 conveys sheet-like paper P as a recording medium set on the paper feed tray 90 one by one along a predetermined conveyance path F. Then, ink as a recording agent is ejected onto the paper P from the print head 11 provided at the center of the lower surface of the carriage 10 that scans and moves in the main scanning direction orthogonal to the paper transport direction Dp corresponding to the print data. Then, an image corresponding to the print data is formed on the paper P. Hereinafter, the configuration of each unit will be described in more detail.

  A paper feed roller 21, a transport roller 31, and a paper discharge roller 43 are provided in order from the upstream side in the paper transport direction Dp along the transport path F, and these operate according to a control command from the control unit 80. As a result, the paper P is transported along the transport path F. Specifically, the paper feed roller 21 has an outer shape in which a part of the outer peripheral surface of the disk is cut out, and is rotated by a paper feed motor 25. When the paper feed motor 25 rotates in response to a control command from the control unit 80, the paper feed roller 21 rotates and comes into contact with the top surface of the paper P set on the paper feed tray 90, As a result, one sheet P is fed into the transport path F.

  The paper P sent to the transport path F by the paper feed roller 21 is sent to the print position PP immediately below the print head 11 by the transport mechanism 30 provided on the downstream side of the paper feed roller 21 in the paper transport direction Dp. In the transport mechanism 30, the transport roller 31 and the driven roller 32 are disposed to face each other with the transport path F interposed therebetween, and the transport roller 31 is rotationally driven by the transport motor 35. When the transport motor 35 rotates in accordance with a control command from the control unit 80, the paper P is sent from the transport nip formed by the contact between the transport roller 31 and the driven roller 32 toward the printing position PP.

  Further, a paper trailing edge sensor 51 that detects the presence or absence of the paper P on the transport path F is provided at a position downstream of the paper feed roller 21 and upstream of the transport mechanism 30. As will be described in detail later, the paper trailing edge sensor 51 is mainly used in this embodiment to determine whether or not the trailing edge of the paper P in the transport direction Dp has passed the position. As the paper trailing edge sensor 51, for example, a sensor using an optical detection method such as a reflective photosensor or a photo interrupter, a sensor using a mechanical detection method such as a microswitch, or the like can be used.

  At the printing position PP, the carriage 10 and the paper guide 91 are opposed to each other with a predetermined gap across the conveyance path F. The carriage 10 is reciprocally scanned in the main scanning direction (Y direction perpendicular to the paper surface in FIG. 1) by the carriage drive mechanism 15 controlled by the control unit 80. At this time, ink is ejected from the print head 11 corresponding to the print data, and the ink adheres to the paper P passing through the print position PP, whereby an image corresponding to the print data is formed. At the printing position PP, a portion corresponding to the position facing the print head 11 on the upper surface of the paper guide 91 slightly rises toward the carriage 10 from the surroundings, and becomes a backup portion 92 that backs up the paper P on which ink is deposited. Yes. Printing can be performed by a known inkjet method, but is not limited thereto. In FIG. 1, a part that is integrally scanned and moved as the carriage 10 is shown separately from other parts by adding a dot pattern hatching.

  A band-like image having a width corresponding to the length of the print head 11 in the X direction is formed on the paper P by one scanning movement of the carriage 10. Accordingly, a two-dimensional image can be formed on the paper P by alternately executing the feeding of the paper P to the printing position PP by the transport mechanism 30 and the scanning movement of the carriage 10.

  In this embodiment, as shown in FIG. 2, an encoder 14 for detecting the position of the carriage 10 in the main scanning direction is provided. For example, the encoder 14 indirectly indicates the position of the carriage 10 by outputting the rotation phase of a linear encoder that outputs position information of the carriage 10 in the apparatus or a motor (not shown) provided in the carriage drive mechanism 15. A rotary encoder or the like can be used. The control unit 80 can grasp the position of the carriage 10 from the output of the encoder 14 and grasp the moving speed of the carriage 10 from the pulse output interval synchronized with the movement of the carriage 10 outputted from the encoder 14, for example. Can do.

  The paper P that has passed the printing position PP is further transported by the transport roller 31 and is sent to a discharge mechanism 40 provided on the downstream side of the printing position PP in the paper transport direction Dp. The discharge mechanism 40 is disposed along the transport path F and is disposed opposite to the first and second serration rollers 41 and 42 that are rotatable about a rotation axis parallel to the Y direction, and the second serration roller 42 across the transport path F. And a paper discharge roller 43. The paper discharge roller 43 is rotationally driven by the transport motor 35. Accordingly, the transport roller 31 and the paper discharge roller 43 rotate in conjunction with each other. A large number of protrusions are provided on the surfaces of the first and second serrated rollers, thereby reducing the contact area with the surface (printing surface) of the sheet P immediately after printing, thereby preventing image smearing. By the discharge mechanism 40 configured in this manner, the paper P that has passed the printing position PP is discharged to a paper discharge tray (not shown).

  In addition to the above, the photo printer 1 includes an interface unit 70 having an input unit 71 and a display unit 72 as shown in FIG. The input unit 71 includes an input interface that receives data from a storage medium that stores images, an external device, and the like, and a keyboard and operation buttons that receive operation input by the user. The input unit 71 transmits the input information to the control unit 80. . In addition, the display unit 72 includes a display made up of a liquid crystal panel, for example, and in response to a control command from the control unit 80, a preview image corresponding to an image to be printed, an operation description, an error message, and the like to be provided to the user. Is displayed on the display.

  In FIG. 1, the end face on the right side, that is, the (+ X) direction side corresponds to the front face (front face) of the photo printer 1, and the end face on the left side, that is, the (−X) direction side is the back face ( It corresponds to the rear surface. In other words, in the photo printer 1, the paper P is taken into the apparatus from the paper feed tray 90 provided at the upper rear side of the apparatus, the image is printed, and the printed paper P is discharged to the paper output tray on the front side of the apparatus. Is done.

  Next, a printing operation in the photo printer 1 configured as described above will be described. In this photo printer 1, when execution of a printing operation is instructed from a user or an external host computer, the control unit 80 generates print job data corresponding to the instruction content and controls each part of the apparatus to perform printing shown below. The designated image is printed on the paper P by executing the operation.

  FIG. 3 is a flowchart showing a printing operation in the photo printer of FIG. FIG. 4 is a diagram schematically showing how the paper is conveyed in the printing operation. In FIG. 4, in order to facilitate understanding, the conveyance path F represented by a curve is actually developed in a straight line and the shape of each part is simplified.

  In this printing operation, first, a paper feed process for feeding one sheet P set in the paper feed tray 90 to the print start position is performed (step S101). More specifically, the sheet feeding roller 21 is rotated to pick up one sheet P from the sheet feeding tray 90, and the sheet P is conveyed to the printing start position by the conveying mechanism 30. This print start position is a position where the leading end portion Pa of the paper P in the transport direction Dp slightly approaches the carriage 10.

  As shown in FIG. 4, at time T 1, the paper feed roller 21 and the transport roller 31 are driven to rotate, and the output of the paper trailing edge sensor 51 at time T 2 when the paper leading edge Pa reaches the detection position immediately below the paper trailing edge sensor 51. Becomes H level indicating the presence of paper. Then, after time T3 when the paper leading end portion Pa reaches the transport nip Nt formed by the transport roller 31 and the driven roller 32, the paper P is transported by the rotation of the transport roller 31, and the front end portion Pa is located below the carriage 10. At time T4 when reaching the printing start position, the rotational driving of the roller is temporarily stopped.

  Subsequently, before executing printing on the paper P, it is determined whether or not a jam detection operation to be described later needs to be performed based on a predetermined determination criterion (step S102). While the previous jam detection operation is executed (step S103), this is skipped if not necessary. As will be described later, this determination is made for each sheet even when images are printed on a plurality of sheets. The criteria for determining whether or not to perform a pre-printing jam detection operation and the contents of the pre-printing jam detection operation will be described in detail later. First, the operation for printing an image on the paper P will be described.

  After the leading edge Pa of the paper P reaches the printing start position, the paper feed roller 21 is not operated, and the paper P is moved along the transport path F by the rotation of the transport roller 31 and the paper discharge roller 43 by the rotation of the transport motor 35. Printing is performed by operating the carriage 10 each time. At this time, the paper transport amount (paper feed amount) at one time by the transport roller 31 is not constant and is dynamically set according to the position of the image to be printed. Specifically, the control unit 80 calculates the distance from the current position on the transport path F to the position where printing is required next, based on the print data corresponding to the content of the image to be formed. Then, a paper feed amount necessary for that is set (step S104). The paper feed amount, that is, the transport distance of the paper P along the transport direction F can be obtained based on, for example, the rotation amount of the transport roller 31 or the number of drive pulses applied to the transport motor 35.

  When printing an image having a continuous spread along the transport direction Dp like a photographic image, the paper P may be transported at a constant pitch corresponding to the length of the print head 11 in the X direction. On the other hand, for an image that is intermittent in the transport direction Dp, such as a wide text image between characters or lines, for example, the paper feed amount is dynamically set and the paper P is advanced at a stroke for areas that do not require printing. The time required for printing can be shortened.

  Subsequently, a paper feed process for advancing the paper P by the previously set paper feed amount along the transport direction Dp is performed (step S105). As a result, an area on the sheet P where a new image is to be printed moves to a position directly below the print head 11. In this state, a printing process is performed in which ink is ejected from the print head 11 according to the print data while the carriage 10 is scanned and moved in the main scanning direction (step S106). As a result, a new belt-like image is printed on the paper P.

  At this time, jam detection is performed based on the load fluctuation in the carriage drive mechanism 15 (step S107). Specifically, it is determined that the load has changed when the generation interval of pulses output from the encoder 14 in synchronization with the movement of the carriage 10 exceeds a predetermined threshold. If a paper jam occurs between the carriage 10 and the paper guide 91, the load viewed from the carriage drive mechanism 15 increases due to the contact between the carriage 10 and the paper P. That is, it can be determined that a jam has occurred between the carriage 10 and the paper guide 91 due to an increase in the load viewed from the carriage drive mechanism 15. In this embodiment, the carriage drive mechanism 15 is driven to scan and move the carriage 10 at a constant speed. However, in view of the fact that the movement speed of the carriage 10 decreases when the load increases due to a jam, the movement speed of the carriage 10 decreases. Jam detection is performed using the output pulse interval of the encoder 14. In this specification, in order to distinguish from “pre-printing jam detection operation” described later, jam detection using carriage load fluctuation during printing processing may be referred to as “printing jam detection”.

  As a jam detection method in this case, in addition to the above, for example, the technique described in Japanese Patent Laid-Open No. 2005-178268 previously disclosed by the applicant of the present application can be applied. That is, in this embodiment, jam detection during the printing process is performed based on the output pulse interval of the encoder 14 indicating the moving speed of the carriage 10 among the physical quantities that change by driving the carriage 10, but other physical quantities such as Jam detection may be performed based on energy consumed by the carriage drive mechanism 15 (more specifically, current consumption or power consumption) or a change in drive torque applied to the carriage 10.

  In addition, the jam detection may be performed not only from the load variation seen from the carriage drive mechanism 15 but also from the load variation seen from the transport motor 35, for example. In short, when the paper P contacts the carriage 10 and the movement of the carriage 10 or the paper P is hindered compared to the case where the paper P is normally transported along the transport path F without contacting the carriage 10. Select a physical quantity that greatly increases and set a threshold value that is larger than the numerical value range that the physical quantity can take during normal conveyance, and determine that there is a jam when the physical quantity exceeds this threshold value. Can do. Conversely, a threshold value lower than the normal numerical range may be set for a physical quantity that greatly decreases when a jam occurs, and it may be determined that a jam has occurred when the physical quantity falls below the threshold value.

  The paper jam discharge operation (step S111) executed when a jam is detected will be described later. If a jam is not detected, it is determined whether there is a remaining print data corresponding to the paper P (step S108), and if there is a remaining print data, the processes in steps S104 to S107 are repeated. During this time, as shown in FIG. 4, the paper feed process by the operation of the transport roller 31 and the paper discharge roller 43 and the printing process by the operation of the carriage 10 are executed alternately. If there is no remaining print data, printing on the paper P has been completed without any problem. Therefore, a front-side discharge process for rotating the paper discharge roller 43 to discharge the printed paper P to a paper discharge tray provided on the front side of the apparatus is performed. This is performed (step S109).

  When printing on one sheet P is thus completed, it is determined whether there is an image to be printed on the next sheet (step S110). If there is a next image, the process returns to step S101, and the image is printed on the next paper P set in the paper feed tray 90 in the same manner as described above. Also at this time, it is determined whether or not a jam detection operation is necessary before printing is performed (step S102), and a pre-print jam detection operation is performed as necessary (step S103). When all the images are printed on the paper P, the printing operation ends normally.

  Here, the positional relationship of each part of the apparatus is determined so as to satisfy the following conditions. Unlike a large-sized printer, this type of photo printer 1 has a strong demand for downsizing and weight reduction of the apparatus, and it is difficult to have a structure that can expose the conveyance path for jamming. Therefore, in this embodiment, firstly, a jam that prevents the paper from being jammed and taken out from the inside of the apparatus is prevented from occurring as much as possible. Second, when a jam occurs, the paper is discharged out of the apparatus as much as possible. The structure and operation sequence of each part is configured so that it can be performed.

  First, the time T7 when the paper trailing edge Pb passes through the conveyance nip Nt is more than the time T5 when the paper leading edge Pa reaches the paper discharge nip Ne formed by the contact between the paper discharge roller 43 and the second knurled roller 42. At a later time, that is, when the paper leading end Pa reaches the paper discharge nip Ne, at least a part of the paper P remains in the transport nip Nt. In other words, the length L1 of the transport path F from the transport nip Nt to the paper discharge nip Ne is set to be shorter than the paper length Lp along the transport direction Dp. If the trailing edge Pb passes through the conveyance nip Nt before the paper leading edge Pa reaches the paper discharge nip Ne, a conveyance force for feeding the paper P to the paper discharge nip Ne may be applied to the paper P thereafter. It is not possible. By satisfying the above conditions, there is a timing (from time T5 to T7) when the paper P is nipped in both the transport nip Nt and the paper discharge nip Ne in normal paper transport. Can be reliably conveyed.

  More preferably, the length L2 of the transport path F from the detection position to the paper discharge nip Ne so that the time T6 when the paper rear end portion Pb passes the detection position by the paper rear end sensor 51 is slightly after the time T5. Is shorter than the paper length Lp along the transport direction Dp. In this way, in normal paper conveyance, the paper leading edge Pa has already reached the paper discharge nip Ne at time T6 when the output of the paper trailing edge sensor 51 changes from H level to L level.

  Therefore, if a jam does not occur until the output of the paper trailing edge sensor 51 changes to the L level, it is considered that at least the paper leading edge Pa has reached the paper discharge nip Ne, and a jam has occurred thereafter. However, it is unlikely that this is caused by an abnormal conveyance of the paper front end portion Pa. For example, such a jam can occur when the rear end Pb of the sheet is warped or bent. On the other hand, if a jam occurs before time T6, it can be said that there is a high possibility that the paper leading edge Pa does not correctly reach the paper discharge nip Ne.

  In this way, by reducing the length L2 of the transport path F from the detection position of the paper trailing edge sensor 51 to the paper discharge nip Ne to be shorter than the paper length Lp along the transport direction Dp, the occurrence of a jam occurs to some extent. Can be estimated. In view of this point, in this embodiment, the contents of the paper jam discharge operation (step S111) executed when a jam is detected during the printing process are as follows.

  FIG. 5 is a flowchart showing the paper jam discharging operation. When the occurrence of a jam is detected from the load variation of the carriage 10, the carriage 10 is first retracted (step S201). In the evacuation process, the scanning movement of the carriage 10 is stopped and the carriage 10 is moved in the direction opposite to the moving direction up to that time, so that the carriage 10 above the sheet P interferes with the sheet P. Evacuate to the home position not on the side. Thereby, it is possible to prevent the paper P and the apparatus from being damaged by the jam.

  At this time, the output of the paper trailing edge sensor 51 is checked (step S202). Since the paper trailing edge sensor 51 is arranged upstream of the conveyance nip Nt in the conveyance direction Dp (left side in FIG. 1), as long as the paper trailing edge sensor 51 detects the presence of paper, the conveyance nip Nt Paper P is present. From this, it can be said that the paper P can be transported at least by the transport mechanism 30. Accordingly, when the output of the paper trailing edge sensor 51 is paper present (H level), the paper P is discharged by the transport roller mechanism 30 toward the rear paper feed tray 90 opposite to the original transport direction Dp. The rear side discharge process is executed (step S203). Specifically, the paper transport direction by the transport roller 31 is reversed by reversing the rotation direction of the transport motor 35.

  Subsequently, a message (paper removal message) prompting the user to remove the paper discharged to the rear paper feed tray 90 and press a confirmation button (not shown) provided on the input unit 71 is displayed on the display unit 72. Display (step S204) and wait for the confirmation button to be pressed (step S205). If it is confirmed that the confirmation button has been pressed, it is assumed that the paper that caused the jam has already been removed, the display of the paper rejection message is canceled (step S206), and the process is terminated. This is an error end different from the case where the operation ends normally (FIG. 3). In the case of an error end, a startup process described later is executed before returning to the normal operation.

  On the other hand, if the output of the paper trailing edge sensor 51 is out of paper (L level) in step S202, the jam does not occur until at least the paper trailing edge portion Pb passes the detection position by the paper trailing edge sensor 51. I can say. Therefore, there is a high possibility that the front end Pa of the paper has reached the paper discharge nip Ne before the jam occurs. On the other hand, whether or not the sheet P remains in the transport nip Nt at this time cannot be uniquely determined. Therefore, in this case, a front-side discharge process is performed in which the paper P is discharged to the front discharge tray along the original transport direction Dp by the discharge mechanism 40 (step S211).

  Then, a sheet rejection message prompting the user to press the confirmation button provided in the input unit 71 after removing the sheet discharged to the front side is displayed on the display unit 72 and waits for the confirmation button to be pressed (step S212). . The operation after the confirmation button is pressed is the same as when the paper is discharged to the rear side.

  As described above, in the printing operation in this embodiment, the jam detection is performed by detecting the speed fluctuation of the carriage 10, and when the jam occurs, the output of the paper trailing edge sensor 51 provided on the upstream side of the transport mechanism 30 is detected. Accordingly, the discharge direction of the paper P is determined. In other words, when the paper trailing edge sensor 51 detects the presence of paper at the time of the occurrence of the jam, the original transport direction Dp is directed toward the paper feed tray 90 by reversing the transport roller 31. Drain in the opposite direction. On the other hand, if the paper trailing edge sensor 51 detects that there is no paper at the time of jam occurrence, the paper discharge roller 43 is rotated forward to discharge the paper P to the paper discharge tray side along the original transport direction Dp. To do.

  For example, in the technique described in Japanese Patent Application Laid-Open No. 2002-068527, the paper discharge direction when a jam occurs is determined by the combination of the outputs of three sensors provided on the conveyance path. A similar function can be achieved by the output of the end sensor 51.

  Returning to FIG. 3, the pre-printing jam detection operation (step S103) will be described. In the printing operation of this embodiment, jam detection is performed based on a change in the speed of the carriage 10, and therefore the carriage 10 needs to be scanned and moved in order to perform jam detection. However, when the printing operation is canceled in the middle, or depending on the content of the image to be printed, the paper P may be advanced greatly without the carriage 10 moving. In such a case, for example, if a jam caused by warping or bending of the paper P occurs, it cannot be detected immediately, and the paper P or the apparatus may be seriously damaged.

  Further, in this photo printer 1, a relatively thick standard size such as a photographic paper or a postcard is assumed as the paper P. However, like a thin paper (having a small basis weight) or a paper having a different size. It is possible that paper that is not originally adapted to this apparatus is set in the paper feed tray 90. Even regular paper may be incompatible due to creases or strong curls. If such a non-conforming paper is used, there is a possibility that the paper cannot be properly conveyed and jammed. When non-conforming paper is used, the paper may be jammed in the apparatus due to a jam and cannot be taken out, and ink may be wasted.

  Therefore, in the photo printer 1, a “pre-print jam detection operation” is performed in which the paper P is sent to the transport path F in advance before printing is started to detect the occurrence of a jam, and a jam that may occur in a subsequent print operation. Can be detected early and accurately. In the printing operation shown in FIG. 3, whether or not a pre-print jam detection operation is necessary is determined in step S102, and if it is determined that it is necessary, a pre-print jam detection operation described later is executed. Two embodiments of the pre-printing jam detection operation according to the present invention will be described below.

First, the criteria for determining whether or not to perform a pre-print jam detection operation in step S102 are as follows, for example.
(1) The content of the instructed printing operation corresponds to a continuous print job for continuously printing images on a plurality of sheets P, and printing is performed when images are printed on the first sheet. Pre-jam detection operation is required. The second and subsequent sheets are unnecessary.
(2) Regardless of the above, a pre-print jam detection operation is performed before the first printing when a continuous print job is interrupted when the paper P does not exist in the paper feed tray 90 and is resumed by paper replenishment. is required.
(3) The content of the instructed printing operation corresponds to a single-leaf print job for printing an image on only one sheet P, and printing is performed on a trial basis before printing on the original sheet P. Therefore, a pre-printing jam detection operation is required if it corresponds to the “test printing mode”.
(4) When the content of the instructed printing operation corresponds to a single-sheet print job that prints an image on only one sheet P and is not in the above-described “test print mode”, jam detection before printing is detected. No action is necessary.

  The standard (1) is based on the assumption that when a plurality of sheets are set on the sheet feed tray 90 for a continuous print job, they are usually of the same type and the same size. That is, it is possible that all of a plurality of set sheets are not compatible with the apparatus, but it is difficult to imagine a situation in which only a part of them is non-compliant. Therefore, by performing a jam detection operation for the first sheet in advance, it is possible to prevent incompatible paper from being used for printing. On the other hand, when the pre-printing jam detection operation is performed for each sheet of paper, the printing throughput decreases. However, by omitting this for the second and subsequent sheets, a decrease in throughput can be suppressed.

  Here, if the number of sheets P set in the sheet feed tray 90 is less than the number of sheets set in the continuous print job, the print job is interrupted when the sheets run out. At this time, for example, a predetermined message can be displayed on the display unit 72 to prompt the user to replenish paper. When the paper is replenished, the print job is resumed. At this time, there is a possibility that a paper that is not suitable for the apparatus is set by mistake. Therefore, by providing the standard (2), it is possible to cope with such a mistake in paper replenishment.

  The standard (3) corresponds to a high possibility that a non-regular paper is used in the test print mode. For example, even when a photo is printed on a thick photo paper, a thinner copy paper may be used in a test print mode for confirming the layout and finish. In this case, the size may be different from the normal one. Therefore, when a single-sheet print job with one printed sheet corresponds to the test print mode, a pre-printing jam detection operation is executed in advance to prevent jamming at the time of printing, and wasteful ink Consumption can be reduced.

  On the other hand, there is naturally a single-leaf print job in which only one sheet is printed, which is performed on regular paper. In such a case, whether or not to perform the pre-printing jam detection operation is arbitrary. However, in the above standard (4), since a mode other than the test print mode is positively selected, regular paper is used. As a result, the pre-print jam detection operation is omitted. Thereby, the first print time can be shortened. Note that it is possible to allow the user to make a setting input as to whether or not to perform a pre-print jam detection operation, and determine whether or not the pre-print jam detection operation is necessary according to the setting state.

  FIG. 6 is a flowchart showing the first embodiment of the pre-printing jam detection operation. FIG. 7 is a diagram showing the paper position on the transport path in the pre-printing jam detection operation. FIG. 8 is a diagram illustrating an example of the posture of the paper P on the transport path F. In the pre-print jam detection operation, a paper feed process for transporting the paper P to a predetermined jam detection position by the rotation of the transport roller 31 is performed (step S301).

  As indicated by the number (1) in FIG. 7, the position where the leading end Pa of the paper P reaches the transport nip Nt and the transport by the transport roller 31 is defined as a “transport start position” for convenience. The “cumulative paper feed amount” used below represents the integrated value of the paper feed amount of the paper P when this position is the starting point. At the start of the pre-print jam detection operation, the leading edge Pa of the paper P is conveyed to the printing start position. At this time, the leading edge Pa of the paper P corresponds to the carriage 10 as shown by the number (2) in FIG. It exists in the position corresponding to the upstream edge part in the conveyance direction Dp among lower surfaces. The accumulated paper feed amount up to this time, that is, the paper feed amount required to move the paper P from the transport start position to the print start position is represented by a symbol Xp.

  The transport amount of the paper P during the pre-printing jam detection operation, that is, the position on the transport path F to which the paper P should be sent during the pre-printing jam detection operation is examined. In order to reliably feed the paper P to the printing position PP without causing a jam, it is desirable that the leading edge Pa of the paper P exceeds at least the printing position PP in the pre-printing jam detection operation. Therefore, the minimum condition in the pre-printing jam detection operation is to convey the paper P along the conveyance path F until the leading end Pa of the paper P exceeds the printing position PP, and to detect whether or not a jam has occurred during this time.

  On the other hand, it is desirable that at least the front end portion Pa of the paper P reaches the discharge mechanism 40 from the viewpoint of preventing the occurrence of a jam until the paper P is discharged out of the apparatus. More specifically, it is desirable that the paper P can be transported by the discharge mechanism 40 by reaching the position where the paper front end portion Pa contacts the discharge mechanism 40. The jam detection position in the photo printer 1 is set based on this viewpoint.

  As shown in FIG. 7 by number (3), the theoretical jam detection position is such that the leading end Pa of the paper P is located on the most upstream side in the transport direction Dp of the discharge mechanism 40, more specifically, in the discharge mechanism 40. It is a position which comes to a contact position with the 1st serration roller 41 to do. This position is referred to as a “discharge mechanism position”, and the accumulated paper feed amount at this time is represented by the symbol Xe. In normal conveyance, as shown in FIGS. 8A and 8B, when the paper leading end Pa reaches the discharge mechanism 40, the paper P is directed toward the discharge tray by the discharge mechanism 40 in the subsequent paper feed. Discharged.

  On the other hand, when the paper P is warped or bent as illustrated in FIG. 8C, a sufficient amount of paper is fed so that the paper front end Pa reaches the discharge mechanism 40. In fact, the paper leading end Pa may not reach the discharge mechanism 40. In such a case, if the paper feeding is continued as it is, there is a possibility that the paper P will leave the transport path F and cause a jam as shown in FIG. In particular, since a guide or the like cannot be brought into contact with the surface of the sheet P immediately after printing, a relatively wide space SP is provided on the downstream side of the carriage 10 in the transport direction Dp. There is a possibility of jamming.

  In the actual transport path F, slight warping or bending of the paper P is allowed to transport the paper P without causing a jam. That is, when the paper feed amount of the paper P is calculated from the transport start position, even if there is a paper transport failure, the paper feed amount exceeds the length L3 of the transport path F from the transport start position to the discharge mechanism 40. It will not always be a jam immediately. However, when the warp or deflection of the sheet due to the conveyance failure exceeds the allowable amount, the sheet P comes into contact with the carriage 10 to cause a jam. Therefore, more realistically, the paper feed amount that determines the start timing of the jam detection operation is preferably slightly longer than the paper feed amount Xe that corresponds to the position from the conveyance start position to the discharge mechanism position.

  Therefore, as indicated by the number (4) in FIG. 7, a predetermined margin amount Xm is added to the accumulated paper feed amount Xe necessary for transporting the paper P from the transport start position to the discharge mechanism 40. The position of the paper P when the paper is fed by the value Xth is set as the actual jam detection position. However, the margin amount Xm is set such that the trailing edge Pb of the sheet does not reach the transport nip Nt when the cumulative sheet feed amount of the sheet P reaches the value Xth. That is, a value L4 obtained by adding the margin amount Xm to the length L3 of the transport path F from the transport nip Nt to the discharge mechanism position is set to be shorter than the length Lp of the paper P along the transport direction Dp. In this way, at least a part of the paper P positioned at the jam detection position is nipped in the transport nip Nt, and a state where the transport by the transport roller 31 is possible is maintained. A specific method of determining the margin amount Xm will be described later. Here, the processing contents of the pre-print jam detection operation will be described with reference to FIG.

  In the pre-printing jam detection operation of this embodiment, the paper P is fed in advance to a position where the leading end Pa of the paper P will surely reach the discharge mechanism 40, and whether or not the paper P is jammed during this conveyance. Is detected. By doing so, it is possible to avoid a jam in a printing operation involving a subsequent carriage movement. Thereby, it is possible to minimize damage to the paper P and the apparatus due to the jam. Also, wasteful consumption of ink due to jam during printing can be suppressed. In addition, if the used paper P is not suitable for the apparatus, it can be detected at this point, so that appropriate measures such as prompting the user to use paper confirmation are taken. be able to.

  Specifically, the jam detection during the sheet conveyance is performed based on the magnitude of the load viewed from the conveyance motor 35 that drives the conveyance roller 31 that conveys the sheet P along the conveyance path F. That is, the interval between output pulses from a rotary encoder (not shown) output in synchronization with the rotation of the transport motor 35, the magnitude of the current supplied to the transport motor 35, and the like are monitored, and the values are within an appropriate range. When it deviates from this, it can be considered that a load fluctuation has occurred on the transport motor 35, and it can be determined that a jam has occurred (step S302 in FIG. 3).

  The jam detection based on the load fluctuation of the transport motor 35 is not performed after the paper P is sent to the jam detection position, but is continuously performed in the entire transport process up to the jam detection position. When a load change is detected, the conveyance of the paper P is immediately stopped at that time.

  If a load change of the transport motor 35 is detected in this process, it is determined that a jam has occurred. This is because the load fluctuation is considered to be caused by the paper leading edge Pa not reaching the discharge mechanism 40 and the paper P staying on the transport path F. In this case, similarly to the case where a jam is detected during the printing process, the discharge process to the rear side (paper feed tray side) and the display of the paper rejection message are performed (steps S311 and S312). Here, the paper discharge direction is fixed to the rear side, as described above, when the accumulated paper feed amount of the paper P is the value Xth, it is guaranteed that the paper P is nipped in the transport nip Nt. This is because the paper P can be reliably discharged in the rear direction.

  If a jam is not detected at this stage, an appropriate sheet P is used, and it can be said that the risk of occurrence of a jam is low in the subsequent paper feeding. Therefore, in this case, in order to return to the normal printing operation, a paper returning process for returning the paper P to the printing start position by the transport roller 31 is executed (step S303). Accordingly, in the subsequent printing operation (after step S104 in FIG. 3), printing can be started from the printing start position as in the case where the pre-printing jam detection operation is not performed.

  Next, how to determine the margin amount Xm will be described. Although it is not impossible to calculate the margin amount Xm based on the length of the transport path F, the hardness of the paper P, the gap between the carriage 10 and the paper guide 91, etc., the situation of the warp or the deflection of the paper is not possible. Since the variation is large, it can be obtained by experiments more realistically.

  The inventor of the present application conducted an experiment to actually perform a jam detection operation by variously changing and setting the margin amount Xm given to the cumulative paper feed amount value Xth corresponding to the jam detection position. As a result, in the area where the margin amount is small, the number of jam detections (the number of times the occurrence of the jam is detected) is small, and the number of jam detections increases as the margin amount increases. Therefore, it is preferable to increase the margin amount in order to detect the jam reliably. However, when the margin amount is increased to some extent, the number of jam detections does not increase any more and becomes substantially constant. Therefore, it is meaningless to increase the margin amount further.

  Further, when the paper P is sent to the jam detection position, the rear end portion Pb of the paper P in the transport direction Dp does not pass through the transport nip Nt, that is, the paper P is still nipped in the transport nip Nt. It is also necessary. This is because if the paper P passes through the conveyance nip Nt, the paper P cannot be returned to the printing start position after the pre-printing jam detection operation is performed. This condition is also necessary in order to prevent the occurrence of a jam after the sheet trailing edge Pb passes through the conveyance nip Nt and the sheet cannot be taken out.

  According to the results of experiments conducted by the inventor of the present application, when the distance from the downstream end of the carriage 10 in the transport direction Dp to the discharge mechanism 40 (first knurled roller 41) is represented by the symbol Xs, the margin amount Xm is the distance. 0.5 times or more of Xs is appropriate. If the margin amount Xm is smaller than this, the probability of detecting in advance a jam that may occur in a subsequent paper feed is reduced. However, if the margin amount Xm is too large, the amount of paper feed at the start of the jam detection operation increases, which takes time for the processing, and jamming due to excessive advancement of the paper leading edge portion Pa toward the discharge mechanism 40. There is a risk of new problems such as In order to prevent this problem, it is preferable to keep the margin amount Xm to be not more than twice the distance Xs. Therefore, the margin amount Xm is preferably about 0.5 to 2 times the distance Xs, and most preferably about the same as the distance Xs. In other words, the sheet conveyance distance from when the sheet leading end Pa reaches the downstream end of the carriage 10 to when the specified jam detection operation starts is reached from the downstream end of the carriage 10 to the discharge mechanism 40. The accumulated paper feed amount threshold value Xth may be set to be 1.5 to 3 times, more preferably about 2 times the transport distance Xs of the paper P.

  In addition to this, as described above, when the cumulative paper feed amount of the paper P reaches the value Xth, the state in which the paper P can be discharged to the paper feed tray 90 side by the transport roller 31 is maintained. Therefore, it is also a necessary condition that at least a part of the paper P remains in the conveyance nip.

  FIG. 9 is a flowchart showing a second embodiment of the pre-print jam detection operation. In the first embodiment (FIG. 6) of the pre-printing jam detection operation, the jam detection is performed by detecting the load fluctuation of the transport motor 35. On the other hand, in the present embodiment, similar to the jam detection in the printing operation, the jam detection during the sheet conveyance is performed based on the load fluctuation of the carriage driving mechanism 15 caused by the scanning movement of the carriage 10.

  Specifically, in the same manner as in the first embodiment, the paper P is transported to the jam detection position (step S401), and in this state, the carriage 10 is scanned and moved from the current position toward one end in the Y direction. (Step S402). Then, jam detection based on the load fluctuation of the carriage drive mechanism 15 is performed (step S403). In this case, when the current carriage position in the Y direction is not the center of the reciprocating range, it is desirable to move the carriage 10 toward the end portion far from the current position. By moving the carriage 10 greatly in this way, it is possible to quickly detect a jam. When a load change is detected in this process, it is determined that a jam has occurred. The processing when a jam occurs is the same as in the first embodiment, and the discharge processing to the rear side (paper feed tray side) and the paper exclusion message are displayed (steps S411 and S412).

  If a jam is not detected at this stage, the carriage 10 is moved to the opposite end to detect the presence or absence of a load change again (steps S404 and S405). Even when a load fluctuation is detected, it is determined that a jam has occurred, and a discharge process to the rear side (paper feed tray side) and a paper rejection message are displayed (steps S411 and S412). On the other hand, if no jam is detected at this time, the risk of jam occurrence is low in subsequent paper feeds. Therefore, in this case, as in the first embodiment, a paper return process for returning the paper P to the print start position is executed (step S406), and the process returns to the printing operation.

  As described above, as the pre-printing jam detection operation, any one that does not accompany the movement of the carriage 10 (first embodiment) and one that accompanies the movement (second embodiment) can be considered. In the pre-printing jam detection operation that does not involve the movement of the carriage 10, contact between the paper P sent to the transport path F and the carriage 10 does not occur. Therefore, even the paper P having a jam generation factor is damaged. It is possible to take out without. Moreover, damage to the carriage 10 can be avoided reliably. On the other hand, in the pre-printing jam detection operation involving the movement of the carriage 10, there is a possibility of contact between the paper P and the carriage 10, but it occurs in the subsequent printing operation by performing the same carriage movement as in the printing operation in advance. It is possible to detect a possible jam more accurately. In any case, since no ink is used, it is possible to avoid waste of ink due to the occurrence of a jam.

  By the way, in the actual use situation of this type of photo printer, after the occurrence of a jam, the apparatus is often restarted without correctly removing the paper causing the jam. Here, since the paper discharged to the paper discharge tray side is already out of the transport path F, there is relatively little problem, but the paper discharged to the paper feed tray 90 side is completely excluded from the transport path F. Therefore, if the apparatus is restarted without being removed, the following problems occur.

  When the apparatus is activated, an initialization operation is generally performed including an operation in which rollers such as the transport roller 31 are idly rotated while also confirming the operation thereof. At this time, if the paper P remains on the transport path F from the paper feed roller 21 to the transport roller 31, the paper is again taken into the apparatus by the rotation of the transport roller 31. In particular, paper discharged due to the occurrence of jam often suffers damage such as bending or breakage, and when such paper is taken into the apparatus, there is a risk of further damage to the paper or the apparatus. Therefore, in this photo printer 1, the processing at the time of starting the apparatus is as follows.

  FIG. 10 is a flowchart showing the activation process in the photo printer of FIG. This activation process is executed, for example, immediately after the apparatus is turned on, and also when the printing operation ends in error (FIGS. 3, 6, and 9). In this activation process, first, the output state of the paper trailing edge sensor 51 is checked (step S501), and when the paper trailing edge sensor 51 detects the absence of paper, the normal initialization operation (step S510) is performed as it is.

  On the other hand, when the paper trailing edge sensor 51 detects the presence of paper at this time, it is considered that the jammed paper discharged to the paper feed tray 90 side remains on the transport path F. This is because the discharging operation by the transport roller 31 does not discharge the paper leading edge Pa in the transport direction Dp to the upstream side of the detection position by the paper trailing edge sensor 51. Further, if the initialization operation is executed in a state where the presence of a sheet (or similar sheet-like foreign matter) is detected on the conveyance path F regardless of the cause, there is a high possibility that a defect such as a jam will occur.

  Therefore, when the paper trailing edge sensor 51 detects the presence of paper at the time of start-up, a paper exclusion message notifying that the paper remains on the rear (paper feed tray 90) side is issued in the same manner as when a jam is detected. The image is displayed on the display unit 72 (step S502), and the user is prompted to remove the paper. Then, it waits for the confirmation button to be pressed (step S503). When the pressing is confirmed, if the paper trailing edge sensor 51 is in a paper-out state at that time, the process proceeds to the initialization operation (step S504), but still the paper. If it is present, it waits for the confirmation button to be pressed until the paper is removed. As a result, the initialization operation is executed in a state where the sheet or sheet-like foreign material is reliably removed from the transport path F, and the above-described problems do not occur.

  As described above, in each of the above-described embodiments, the carriage 10 and the carriage driving mechanism 15 function as the “carriage” and the “driving unit” of the present invention, respectively, and these together form the “printing unit” of the present invention. Is functioning as In the present embodiment, the control unit 80 functions as the “control unit” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described one without departing from the spirit of the present invention. For example, in the above embodiment, the accumulated paper feed amount is integrated with the position where the paper leading edge Pa is in the transport nip Nt as the transport start position, but the starting point of the paper feed amount, that is, the transport distance of the paper P is limited to this. It is not optional. For example, the transport distance may be obtained based on the detection position of the paper trailing edge sensor 51, the print start position, or the like.

  Further, for example, in the above-described embodiment, the jam detection is performed by reciprocating the carriage 10 during the pre-printing jam detection operation to detect the presence or absence of load variation. However, for example, the jam is detected by moving the carriage 10 only in one direction. Detection may be performed. In the second embodiment of the pre-printing jam detection operation, the moving speed of the carriage 10 at the time of jam detection is not particularly limited, but can be set to the same speed as that at the time of print processing, for example. Further, if the speed is faster than that during the printing process, the time required for the pre-printing jam detection operation can be shortened. On the other hand, if the speed is slower than that during the printing process, damage to the paper P before the carriage 10 stops when a jam occurs can be minimized.

  In the above-described embodiment, the pre-print jam detection operation is executed only before the first printing in the continuous print job. In addition, for example, every time the number of printed sheets reaches a predetermined number, A pre-printing jam detection operation may be executed prior to the next printing.

  In the second embodiment, jam detection based on carriage load variation is performed both during the printing process and during pre-print jam detection operation. Specifically, the output of the encoder 14 indicating the moving speed of the carriage 10 is performed. A jam is determined when the pulse interval exceeds a predetermined threshold (that is, the carriage moving speed is lower than a predetermined value). The threshold value in this case is not particularly limited, and each threshold value may be a common value or an individual threshold value may be set. For example, if the threshold value at the time of jam detection operation is set lower than that at the time of print processing, the paper P is transported under conditions that are stricter than those at the time of print processing. Can be detected.

  Further, since the degree of decrease in the movement speed of the carriage 10 due to the contact with the paper P also depends on the original movement speed, for example, when the movement speed of the carriage 10 can be changed in a plurality of stages, for each movement speed. A threshold value for jam detection may be set.

  Further, for example, in the above embodiment, the present invention is applied to an ink jet photo printer which is a kind of printing apparatus, but the application target of the present invention is not limited to this, and a printing apparatus other than the photo printer is used. The present invention can be applied to various printing apparatuses that perform printing by scanning and moving a carriage with respect to a recording medium to be transported even if the printing apparatus is not based on an inkjet system (for example, a thermal system). It is.

  DESCRIPTION OF SYMBOLS 10 ... Carriage (printing means), 11 ... Print head, 15 ... Carriage drive mechanism (drive part, printing means), 21 ... Paper feed roller, 30 ... Conveyance mechanism, 31 ... Conveyance roller, 35 ... Conveyance motor, 40 ... Discharge Mechanism: 41 ... first jagged roller, 42 ... second jagged roller, 43 ... discharge roller, 80 ... control unit (control means), Dp ... paper conveying direction, F ... conveying path, P ... paper (recording medium), PP ... Print position

Claims (8)

A transport mechanism that feeds a recording medium toward a printing position along a predetermined transport path;
A carriage disposed opposite to the recording medium fed to the printing position; and a drive unit that scans and moves the carriage in a main scanning direction different from the conveyance direction of the recording medium along the conveyance path. Printing means for applying a recording agent to the recording medium and printing an image on the recording medium;
Prior to execution of printing by the printing means, the recording medium is transported by the transport mechanism so that the leading end of the recording medium in the transport direction exceeds the print position, and the recording in the transport path during the transport is performed. A printing apparatus comprising: control means for executing a pre-printing jam detection operation for detecting a jam of a medium.   When a jam is not detected in the pre-printing jam detection operation, the transport mechanism moves the recording medium to a position at which printing starts on the recording medium, and the printing unit moves the recording medium relative to the recording medium. The printing apparatus according to claim 1, which prints an image. A discharge mechanism for discharging the recording medium that has passed through the printing position along the transport path;
3. The pre-printing jam detection operation according to claim 1, wherein a transport distance of the leading end portion of the recording medium from the print position is equal to or longer than a length of the transport path from the print position to the discharge mechanism. Printing device.   4. The jam detection operation according to claim 1, wherein in the jam detection operation, the control unit detects a jam of the recording medium based on a magnitude of a load applied to the transport mechanism as the recording medium is transported. 5. Printing device.   4. The printing apparatus according to claim 1, wherein in the jam detection operation, the control unit detects a jam of the recording medium based on a physical quantity that changes due to driving of the carriage by the driving unit. 5. .   A continuous print job for printing an image on a plurality of recording media is executed, and in the continuous print job, before printing on a part of the recording media including the first one of the plurality of recording media, before the printing The printing apparatus according to claim 1, wherein a jam detection operation is executed.   A single-leaf print job for printing an image on one sheet of the recording medium is executed. In the single-leaf print job, printing with the pre-printing jam detection operation and printing without the pre-printing jam detection operation are selectively performed. The printing apparatus according to claim 1, wherein the printing apparatus is executed. A carriage that feeds a recording medium toward a printing position along a predetermined conveyance path by a conveyance mechanism, and that scans and moves in a main scanning direction different from the conveyance direction of the recording medium with respect to the recording medium sent to the printing position. In a control method for a printing apparatus for printing an image on the recording medium by applying a recording agent from
Prior to execution of printing, the recording medium is conveyed by the conveyance mechanism so that the leading end portion of the recording medium in the conveyance direction exceeds the printing position, and a jam of the recording medium in the conveyance path during the conveyance is detected. A printing apparatus control method, comprising: performing a pre-printing jam detection operation.

Images