PRINTING APPARATUS, CONTROL METHOD THEREFOR, AND STORAGE MEDIUM

A printing apparatus, comprising a printing unit, a first conveying unit, a second conveying unit at downstream side in a conveying direction of the first conveying unit, and a control unit for executing a first control such that a leading end portion of a second print medium succeeding a first print medium overlaps a trailing end portion of the first print medium and a second control such that the first and second print mediums are separated, wherein, in the second control, conveyance of the second print medium is suppressed while the printing unit is located in a region other than the to-be-printed region.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a printing apparatus.

Description of the Related Art

Some of the printing apparatuses such as inkjet printers are configured to consecutively feed two or more sheet-like media, sequentially perform printing on the media, and convey the media in an overlap state during the printing (Japanese Patent Laid-Open No. 6-56299). Such a conveyance mode is also expressed as successive overlapped conveyance. This conveyance mode can improve the efficiency of printing processing.

In the above printing apparatus, two or more printed media are separated (the overlap state of the media is canceled) and then discharged. This operation is performed by inhibiting the conveyance of a succeeding medium with respect to a preceding medium. Accordingly, this can affect the quality of printing on the succeeding medium.

SUMMARY OF THE INVENTION

The present invention provides a technique advantageous in suppressing or reducing the deterioration in the print quality.

One of the aspects of the present invention provides a printing apparatus, comprising a printing unit configured to perform printing on a print medium, a first conveying unit configured to convey the print medium in a conveying direction, a second conveying unit configured to convey the print medium conveyed by the first conveying unit, and a control unit configured to execute first control to control the first conveying unit and the second conveying unit so as to make a leading end portion of a second print medium succeeding a first print medium overlap a trailing end portion of the first print medium, wherein in a case where a region on the second print medium on which printing is performed by the printing unit is a to-be-printed region, the control unit executes second control to control the first conveying unit and the second conveying unit so as to separate the first print medium and the second print medium made to overlap each other by the first control, and in the second control, conveyance of the second print medium is suppressed while the printing unit is located in a region other than the to-be-printed region.

DESCRIPTION OF THE EMBODIMENTS

FIG.1is a schematic view for explaining an example of the arrangement of a printing apparatus9according to an embodiment.FIG.1exemplarily shows operation states ST1 to ST3 in the printing apparatus9. The printing apparatus9includes a carriage1, a printhead7, a platen8, a sheet stacking unit11, a detection sensor16, a paper discharge unit25, and rollers2to6,10,12, and20to23.

In the state ST1, sheet-like print media P such as cut sheets are stacked on the sheet stacking unit11. The roller2is a pickup roller that picks up the one print medium P by rotating in contact with the uppermost one of the plurality of print media P stacked on the sheet stacking unit11. The roller3is a feed roller that feeds the picked-up print medium P to the downstream side in the conveying direction along the inside of a conveyance path100. The roller4is a driven roller that is biased against the feed roller3to feed the print medium P while holding the print medium P together with the feed roller3.

Note that the conveying direction in this case indicates the conveying direction of the print medium P. The downstream side indicates the side in the same direction as the conveying direction of the print medium P, and the side opposite to the conveying direction is expressed as the upstream side. In addition, an end of the print medium P on the downstream side is expressed as a leading end, and an end of the print medium P on the upstream side is expressed as a trailing end.

A one-way roller is used as the pickup roller2. When the picked-up print medium P reaches the position of the rollers3and4, and the rollers3and4start to feed the print medium P, the driving of the pickup roller2may be stopped. In this case, the pickup roller2idles until the trailing end of the print medium P passes and can be inhibited from picking up the next print medium P.

The roller5is a conveyance roller that conveys the print medium P fed by the rollers3and4to a position facing the printhead7. The roller6is a driven roller that is biased against the conveyance roller5to convey the print medium P while holding the print medium P together with the conveyance roller5.

The rollers3and4described above form a feed nip portion. The rollers5and6form a conveyance nip portion. The print medium P is properly guided along a predetermined path in the conveyance path100between these nip portions. The detection sensor16is provided on the downstream side of the rollers3and4and can detect the conveyed print medium P (its leading end and trailing end).

In the state ST2, the printhead7performs printing on the print medium P conveyed by the rollers5and6. In this embodiment, the printhead7is an inkjet head that can execute printing on the print medium P by causing a nozzle71(seeFIG.7and the like) (to be described later) to discharge ink. The platen8is arranged to face the printhead7and supports the print medium P from the reverse surface of the print medium P (the surface on the opposite side to the printing surface).

The carriage1is equipped with the printhead7and causes the printhead7to scan in a direction crossing the conveying direction (the crossing direction will be referred to as a scanning direction). In such an arrangement, the printhead7is also expressed as a serial head, and the printing apparatus9can also be expressed as a serial printer.

The roller10is a conveyance roller that conveys, toward the roller20, the print medium P on which printing has been performed by the printhead7. The roller12is a driven roller that is biased against the conveyance roller10to convey the printed print medium P while holding the print medium P together with the conveyance roller10.

In the state ST3, the printed print medium P is discharged to the paper discharge unit25. The roller20is a conveyance roller that conveys the printed print medium P which is conveyed by the rollers10and12. The roller21is a driven roller that is biased against the conveyance roller20to convey the printed print medium P while holding the print medium P together with the conveyance roller21.

The roller22is a paper discharge roller that is arranged upstream of the paper discharge unit25and discharges, to the paper discharge unit25, the printed print medium P which is conveyed from the conveyance roller20to a conveyance path (paper discharge path)104. The roller23is a driven roller that is biased against the paper discharge roller22to discharge, to the paper discharge unit25, the printed print medium P while holding the print medium P together with the paper discharge roller22.

FIG.2is a block diagram showing an example of the system arrangement of the printing apparatus9. The printing apparatus9further includes a CPU201, a ROM202, a RAM203, and an interface (I/F) unit213.

The central processing unit (CPU)201controls the operation of each element and performs arithmetic processing required for the control. Although described in detail later, the CPU201can control each roller described above to convey the two print media to be conveyed consecutively such that the trailing end portion of one preceding print medium overlaps the leading end portion of one succeeding print medium.

The read only memory (ROM)202holds information such as programs to be executed by the CPU201and data. The random access memory (RAM)203temporarily holds input data received from a host computer214via the I/F unit213and also temporarily holds the processed data obtained by arithmetic processing by the CPU201.

The printing apparatus9further includes a printhead driver217, a motor driver218, and motors204,205,206,207, and215. The motor driver218individually controls the motors204,205,206,207, and215.

For example, the motor driver218drives the pickup roller2by performing drive control of the feed motor206, and drives the feed roller3by performing drive control of the feed motor207, thereby conveying the print medium P from the sheet stacking unit11to the printing position where the printhead7performs printing.

In response to the detection of the passage of the print medium P by the detection sensor16, the motor driver218drives the conveyance rollers5and10by performing drive control of the conveyance motor205to move the print medium P relative to the printhead7. During this movement, the motor driver218drives the carriage1by performing drive control of the carriage motor204, thereby scanning the printhead7. Together with this operation, the printhead driver217implements printing on the print medium P by performing drive control of the printhead7.

Subsequently, the motor driver218drives the conveyance roller20and the paper discharge roller22by performing drive control of the paper discharge motor215, thereby discharging the printed print medium P to the paper discharge unit25.

This embodiment, in which the printhead7is a serial head, is configured to alternately repeat the operation (intermittent conveying operation) of intermittently conveying the print medium P with the conveyance roller5by a predetermined amount at a time and the operation (scanning operation) of discharging ink from the printhead7while scanning the printhead7with the carriage1between intermittent conveyances (that is, during the inhibition of the conveyance of the print medium P). With this operation, printing is performed on the print medium P.

In this case, other rollers (not shown) can be driven in the same manner by the motor driver218and the corresponding motors.

The host computer214includes a printer driver2141for communicating with the printing apparatus9. Upon receiving an operation input for instructing the execution of printing from the user, the host computer214outputs data indicating a print image as a printing job together with print information indicating its quality or the like. In the printing apparatus9, the CPU201performs arithmetic processing upon receiving a print job via the I/F unit213and controls the drivers217and218based on the processing result.

The following case will exemplify a printing operation with reference toFIGS.4to6likeFIG.1when one print job includes two-page print data respectively corresponding to the two sheets of the print media P.

FIG.3shows a mode of a printing order, that is, the operation of performing printing based on the first-page print data on the first print medium P and then performing printing based on the second-page print data on the second print medium P. Note that the printing order in this case is set according to a scheme of discharging the print medium P in a posture in which the obverse surface (printing surface) faces down, that is, the so-called face down scheme, and is not limited to this case.

As shown inFIG.4, first of all, the feed motor206is driven at a relatively low speed to rotate the pickup roller2at 7.6 inches/sec (state ST11). The pickup roller2is rotated to pick up one uppermost sheet of the plurality of print media P (to be referred to as a first print medium P1) stacked on the sheet stacking unit11. The feed roller3is driven by the feed motor207to rotate at substantially the same speed as that of the pickup roller2in the same direction, and the picked-up print medium P1 is then conveyed by the feed roller3.

For the sake of easy description, the driving mode or the conveyance mode (driving at 7.6 inches/sec) at this time is expressed as low-speed driving or low-speed conveyance.

As described above, a one-way roller is used as the pickup roller2. After the pickup roller2rotates until the print medium P1 passes through the feed roller3, the pickup roller2idles by inhibition of the driving. Thereafter, the print medium P1 is continuously conveyed by the feed roller3.

The detection sensor16detects the print medium P1 conveyed in this manner. When the detection sensor16detects the leading end of the print medium P1, the driving mode of the feed motor207is switched to drive the feed motor207at a relatively high speed, thereby rotating the feed roller3at 20 inches/sec.

For the sake of easy description, the driving mode or the conveyance mode (driving at 20 inches/sec) will be expressed as high-speed driving or high-speed conveyance hereinafter.

Subsequently, the feed roller3continues to rotate, and the leading end of the print medium P1 abuts against the conveyance nip formed by the rollers5and6(state ST12). At this time, the conveyance roller5is set in a halt state/non-driven state. After the leading end of the print medium P1 abuts against the conveyance nip portion formed by the rollers5and6, the feed roller3rotates by a predetermined amount to align the print medium P1 while its leading end abuts against the conveyance nip portion, thereby correcting the skew of the print medium (skew correcting operation).

After the skew correcting operation for the print medium P1 is completed, the conveyance motor205is driven to start rotating the conveyance roller5. This causes the conveyance roller5to convey the print medium P1 at 15 inches/sec (state ST13). After the print medium P1 reaches a printing operation start position at which the print medium P1 faces the printhead7, the printhead7starts printing based on print data on the print medium P1.

Note that the operation of adjusting the print medium P1 at the printing operation start position is performed by positioning the print medium P1 by causing the leading end of the print medium P1 to abut against the conveyance nip portion (the rollers5and6) using the conveyance roller5and then rotating the conveyance roller5by a predetermined amount with reference to the position of the print medium P1.

When the print medium P1 is adjusted to the printing operation start position, the feed motor207is switched to low-speed driving, thereby rotating the feed roller3at 7.6 inches/sec. During the execution of the printing operation, the print medium P1 is intermittently conveyed. During this period, the conveyance roller5is intermittently driven. The feed motor207intermittently drives the feed roller3in synchronism with this driving. At this time, the driving forces of the rollers3and5are adjusted to set the print medium P1 in a pulled state between the rollers3and5. With this adjustment, the rotational speed (rotation amount) of the feed roller3in the absence of the print medium P1 is lower than that of the conveyance roller5. Accordingly, the feed roller3is rotated by the conveyance roller5through the print medium P1. That is, the feed roller3rotates at the same rotational speed as that of the conveyance roller5.

Note that while the print medium P1 is intermittently conveyed, the paper discharge motor215intermittently drives the conveyance roller20like the conveyance roller5.

As shown inFIG.5, subsequently, like the print medium P1, the succeeding print medium P (a second print medium P2) is picked up by the pickup roller2and then conveyed by the feed roller3(state ST14). In this state, the printhead7is performing printing on the print medium P1. When the detection sensor16detects the leading end of the print medium P2, the feed motor207is switched to high-speed driving to rotate the feed roller3at 20 inches/sec.

In this case, in order to allow the detection sensor16to properly detect an end portion of each print medium P, in consideration of the responsiveness and the like of the detection sensor16, a predetermined interval is required between the two print media P conveyed consecutively. Accordingly, in order to allow the detection sensor16to detect the leading end of the succeeding print medium P2 after detecting the trailing end of the print medium P1, an interval corresponding to the time responsiveness of the detection sensor16needs to be provided between the trailing end of the print medium P1 and the leading end of the succeeding print medium P2.

In this embodiment, the print medium P2 is picked up in response to the detection of the passage of the trailing end of the print medium P1 through the detection sensor16. The pickup roller2is controlled to form an interval equal to or larger than a predetermined distance between the trailing end of the print medium P1 and the leading end of the print medium P2.

After state ST14, the print medium P2 is conveyed at a speed higher than that of the printed print medium P1 by the printhead7conveyed downstream (the speed of the print medium P1 currently conveyed; the same applies below) (state ST15). This causes the leading end of the print medium P2 to overlap above the trailing end of the print medium P1. Continuously driving the feed roller3at a rotational speed of 20 inches/sec in response to the detection of the leading end of the print medium P2 by the detection sensor16will cause the leading end of the print medium P2 to catch up to the trailing end of the print medium P1. The print medium P2 is conveyed by the feed roller3until the leading end of the print medium P2 reaches a predetermined position on the upstream side of the conveyance nip portion (the rollers5and6). The position of the leading end of the print medium P2 can be calculated from the rotation amount of the feed roller3from the time when the leading end of the print medium P2 is detected by the detection sensor16. The feed roller3is controlled based on the calculation result.

Subsequently, while the conveyance roller5is stopped to perform the last scanning of the printhead7on the print medium P1 (which can be expressed as the printing of the last line, the image formation of the last line, or the like), the feed roller3is driven to cause the leading end of the print medium P2 to abut against the conveyance nip portion, thereby correcting the skew of the print medium P2 (state ST16).

As shown inFIG.6, in response to the completion of the last scanning of the printhead7on the print medium P1, the conveyance roller5is rotated by a predetermined amount (state ST17). This will adjust the print medium P2 at the printing operation start position while maintaining the state in which the print medium P2 overlaps the print medium P1.

When the print medium P2 is adjusted at the printing operation start position, the feed motor207is switched to low-speed driving as in a printing operation for the print medium P1, thereby rotating the feed roller3at 7.6 inches/sec. During the execution of a printing operation, the print medium P2 is intermittently conveyed, and the printhead7starts the next printing based on print data on the print medium P2. When the print medium P2 is intermittently conveyed, the print medium P1 is also intermittently conveyed.

In this manner, while the succeeding print medium P2 overlaps the preceding print medium P1, a conveying operation is performed (to be referred to as successive overlapped conveyance hereinafter).

In the above successive overlapped conveyance, it is conceivable that when paper discharging is performed in a face-down manner in this state, the order of sheets is interchanged. This can cause a deterioration in paper discharging performance.

Although described in detail later in this embodiment, the operation of separating (to be referred to as a separating operation hereinafter) the print medium P1 and the print medium P2 is performed to prevent a deterioration in paper discharging performance by performing paper discharging while the print media do not overlap each other.

At least two rollers are used to implement a separating operation. In this embodiment, one of these rollers which is located on the upstream side is the conveyance roller10, and the other roller on the downstream side is the conveyance roller20. Whether the trailing end of the print medium P1 has passed through the conveyance roller10(state ST18A) is determined based on the rotation amount of the conveyance roller5from the start of a printing operation on the print medium P and the length of the print medium (sheet length).

FIG.7Ais a schematic top view showing the state ST18A. In this state, the paper discharge motor215continuously rotates the conveyance roller20and the paper discharge roller22independently of the conveyance rollers5and10, thereby implementing a separating operation.

Note that in this embodiment in which the printing apparatus9is a serial printer, during the execution of a separating operation, an intermittent conveying operation for the print medium P and the scanning operation of the printhead7between the intermittent conveyances are alternately repeated.

In this case, as shown inFIG.7A, V1 represents the conveying speed of the conveyance rollers5and10, and V2 represents the conveying speed of the conveyance roller20and the paper discharge roller22. In addition, W represents the overlap amount between the print media P1 and P2, Dr represents the distance from the separation start position to the most downstream position of the nozzle71. A most downstream position Hs of the nozzle71is calculated as W+Dr from the leading end of the print medium P2.

Note that the conveying speed of the conveyance roller20and the paper discharge roller22is provided with an upper limit V2max (V2max≥V2) for the prevention of noise, low power consumption, or the like as a purpose. Although described in detail later, a wait operation of stopping the conveyance rollers5and10can be performed.

After the separating operation is started, the conveyance roller20conveys the print medium P1, and the trailing end passes through the conveyance roller20(state ST18B).

FIG.7Bis a schematic top view showing the state ST18B. In this state, although described in detail later, the speed of the conveyance roller20and the time and timing of a wait operation are controlled so as to complete the separating operation when the interval between the trailing end of the print medium P1 and the leading end of the print medium P2 becomes a distance Dp (Dp≥0 (preferably Dp>o)). This will properly separate the print media P1 and P2 from each other and cancel the state in which the trailing end of the print medium P1 overlaps the leading end of the print medium P2.

In this case, as shown inFIG.7B, L represents the distance from a separation start position to a separation end position. A most downstream position He of a nozzle71is calculated as L−Dp+Dr from the leading end of the print medium P2.

FIG.7Cis a schematic view for comparison between the positions Hs and He described above. The region between the positions Hs and He corresponds to a region on a sheet at which a separating operation is executed with reference to the most downstream position of the nozzle71and will be referred to as a separation region Rh. A distance (length or width) Lh of the separation region Rh is calculated as

and the separation region Rh corresponds to a region where the print medium P2 passes through the conveyance roller10in the interval between the instant when the trailing end of the print medium P1 passes through the conveyance roller10and the instant when the trailing end passes through the conveyance roller20.

The driving mode for implementing a separating operation may be partially changed without departing the gist of the driving mode. For example, the positions Hs and He may be located at the most downstream position of the nozzle71used in each printing operation and may be changed for each printing operation.

The timing when a separating operation is started may be after the timing when the trailing end of the print medium P1 passes through the conveyance roller10. In addition, the timing when the separating operation is ended may be controlled such that the interval between the trailing end of the print medium P1 and the leading end of the print medium P2 becomes equal to or more than the distance Dp.

In this example, a separating operation is ended at the timing when the trailing end of the print medium P1 passes through the conveyance roller20. In another example, the separating operation may be ended until the trailing end of the print medium P1 passes through an arbitrary point set in advance.

In this example, the rollers10and20are mainly used for a separating operation. However, in another example, when the conveyance roller10is a one-way roller, the rollers5and10may be mainly used for a separating operation. That is, of the two rollers mainly used for a separating operation, one roller on the upstream side may be positioned upstream or downstream of the printhead7.

As described above, the conveying speed of the conveyance roller20and the paper discharge roller22is provided with an upper limit V2max. The conveying speed required for the execution of a separating operation may exceed the upper limit speed depending on the contents of print data.

Accordingly, in this embodiment, a wait operation can be executed during the execution of a separating operation. In a wait operation, while an intermittent conveying operation for the print medium P and the scanning operation of the printhead7between the conveyances are alternately repeated, the conveyance rollers5and10are stopped. A printing operation performed by alternately repeating an intermittent conveying operation and a scanning operation is interrupted by a wait operation.

A description will be made with reference toFIGS.8A and8Bin a case where a wait operation is executed during the execution of a separating operation, which is also a case where a printing operation to be continued is interrupted by a wait operation.FIG.8Ais a schematic top view showing the timing when a separating operation is started.FIG.8Bis a schematic top view showing the timing when the separating operation is ended during the execution of a wait operation.

In this state, the conveyance rollers5and10are stopped, and the region immediately below the nozzle71is ready for printing. A region Kd1 inFIG.8Bindicates a printed region on the preceding print medium P1. A region Kd2 inFIG.8Bindicates a printed region on the succeeding print medium P2. A region Ky2 inFIG.8Bindicates a to-be-printed (non-printed) region on the succeeding print medium P2.

In this case, when a wait operation is performed in the state inFIG.8B, the time difference since ink is discharged is relatively large between the printed region Kd2 on which printing has been performed before a wait operation and the to-be-printed region Ky2 on which printing is to be performed after the wait operation. This can be a cause for color unevenness between the regions Kd2 and Ky2 on the same print medium P2 due to the time difference until ink is dried and eventually can be a cause for a deterioration in print quality.

Accordingly, a wait operation is preferably performed on the to-be-printed region Ky2 which is not continuous with the printed region Kd2. A region where such a wait operation can be executed will be described as a wait enable region.

As exemplarily shown inFIG.9A, the region between the two to-be-printed regions Ky2 spaced away from each other is defined as a wait enable region Rw, and the distance (length or width) between the two to-be-printed regions is represented by Lw. In this case, the to-be-printed region Ky2 changes to the printed region Kd2 after printing is performed. Accordingly, the wait enable region Rw can also be a region other than the to-be-printed region Ky2 in the state before a printing operation, and in short can be a region other than a print target or a region on which no scanning operation is performed.

A wait operation is performed at the timing when the region common to the separation region Rh and the wait enable region Rw includes the most downstream position of the nozzle71(a calculation method for the timing will be described in detail later). This makes it possible to suppress or reduce the deterioration in print quality described above. As an example, a wait operation is preferably performed when the most downstream position of the nozzle71is located on the upstream end of the region common to the separation region Rh and the wait enable region Rw.

FIG.9Bshows a mode in which a wait operation according to this embodiment can be properly executed during the execution of a separating operation. Note that a distance Dp′ between the trailing end of the print medium P1 and the leading end of the print medium P2 in this case is smaller than the distance Dp described above (Dp′<Dp). During the execution of a wait operation, the driving of the conveyance rollers5and10and a printing operation for the region immediately below the nozzle71are suppressed.

FIG.9Cshows a state in which the distance between the trailing end of the print medium P1 and the leading end of the print medium P2 becomes the distance Dp, and the separating operation is ended. In accompanying with this operation, the intermittent conveyance by the conveyance rollers5and10is resumed (the conveying speed V1), that is, the wait operation is ended.

As shown inFIG.10, the printed print medium P1 is discharged in this manner onto the paper discharge unit25by the conveyance roller20and the paper discharge roller22(state ST19). With a similar procedure, the print medium P2 having undergone printing is discharged onto the paper discharge unit25by the conveyance roller20and the paper discharge roller22(state ST20).

In this manner, successive overlapped conveyance, a separating operation, and a wait operation are performed to perform a printing operation for the plurality of print media P. Although each operation has been described by exemplifying the case of one-side printing, the contents described above can also be applied to the case of two-sided printing.

<Contents of Control for Execution of Successive Overlapped Conveyance>

The contents of control for implementing a printing operation accompanying successive overlapped conveyance according to this embodiment will be described with reference toFIGS.11A to15. Generalized control contents will be described by using, as parameters, a printing order N, a page K in print data, and a page count M of print media (N is an arbitrary integer from 1 to Nmax) as exemplified inFIG.3.

Assume that N, K, and M correspond to each other, that is, N is an integer from 1 to Nmax, and printing is performed on the N(K)th page of the N(M)th print medium at the Nth turn.

FIGS.11A and11Bshow flowchart S30indicating overall control contents at the time of the execution of a printing operation. Flowchart S30can be executed mainly by the CPU201.

In step S301(to be simply referred to as “S301” hereinafter; the same applies to the other steps to be described later), the parameter N is initialized as N=1. In S302, the parameter Nmax is obtained based on print data. In S304, the Nth print medium is started to be fed by low-speed driving (conveying speed of 7.6 inches/sec).

In S305, it is determined whether the leading end of the Nth print medium has passed through the sensor16. If the leading end of the Nth print medium has passed through the sensor16(YES in the determination), the process advances to S306; otherwise (NO in the determination), the process returns to S305.

In S306, the conveyance mode of the Nth print medium is switched to high-speed driving (conveying speed of 20 inches/sec). With this operation, the leading end of the Nth print medium catches up the trailing end of the (N−1)th print medium.

In S307, it is determined whether N=1. If N=1 (YES in the determination), that is, there is no preceding print medium P that should be overlapped, the process advances to S308. In contrast to this, if N≠1 (NO in the determination), that is, there is a possibility that successive overlapped conveyance may be performed, wait calculation processing (to be described later) is executed in S70. Based on the processing result, overlap preparation operation (to be described later) is executed in S40.

FIG.12is a flowchart showing the control contents in overlap preparation operation S40. In S401, the Nth print medium is stopped at a predetermined position in front of the conveyance roller5based on the detection result obtained by the detection sensor16and the rotation amount of the feed roller3.

In S402, it is determined whether exception processing flag Fr=0, which indicates whether exception processing (to be described later) is performed (Fr=0 indicates that exception processing is not performed, and Fr=1 indicates that exception processing is performed). If Fr=0 (YES in the determination), the process advances to S403; otherwise (NO in the determination), the process advances to S404.

Although described in detail later, the exception processing flag Fr can be calculated in wait calculation processing (S70) before the formation of an overlap state between the (N−1)th print medium and the Nth print medium by successive overlapped conveyance.

In S403, it is determined whether the last scanning of the printhead7with respect to the (N−1)th print medium is completed. If the last scanning is completed (YES in the determination), flowchart S40is terminated, and the process advances to S308inFIG.11A; otherwise (NO in the determination), the process returns to S403.

In S404, exception processing is performed. In this embodiment, as an example, processing for canceling the overlap state between the (N−1)th print medium and the Nth print medium, more specifically, the conveyance of the succeeding Nth print medium is set standby until the preceding (N−1)th print medium passes through the conveyance roller5. This prevents a wait operation from being needlessly performed during the execution of a separating operation, thereby suppressing or reducing a deterioration in print quality. As another example, a similar effect can also be obtained by adjusting the overlap amount W. For example, in order to reduce the overlap amount W, the (N−1)th print medium may be conveyed by a predetermined amount.

Referring toFIGS.11A and11Bagain, in S308, the skew of the Nth print medium is corrected. In this case, if it is determined in S307that N=1 (YES in the determination in S307), the skew of the Nth print medium is independently corrected. If it is determined in S402that Fr=0 (YES in the determination in S402), the skew of the Nth print medium is corrected in an overlap state with the (N−1)th print medium. In contrast to this, if it is determined in S402that Fr=1 (NO in the determination in S402), the skew of the Nth print medium is independently corrected.

In S309, the Nth print medium is adjusted at a printing operation start position. If the skew of the Nth print medium is corrected in S308in an overlap state with the (N−1)th print medium, the adjustment is performed in this state. In S310, the conveyance mode of the Nth print medium is switched to low-speed driving (a conveying speed of 7.6 inches/sec). In S311, a printing operation for the Nth page of the Nth print medium is started.

In S312, it is determined whether N=1. If N=1 (YES in the determination), the process advances to S313; otherwise (NO in the determination), the process advances to S316.

In S316, it is determined whether successive overlapped conveyance is executed. If successive overlapped conveyance is executed (YES in the determination), a separating operation is executed in S50, although described in detail later, and the process advances to S318; otherwise (NO in the determination), the process skips S50and advances to S318. In S318, the (N−1)th print medium is discharged onto the paper discharge unit25.

In S313, the parameter N is incremented (N=N+1).

In S314, it is determined whether N≤Nmax (YES in the determination), the process advances to S315; otherwise (NO in the determination), the process advances to S317.

In S315, it is determined whether the trailing end of the (N−1)th print medium has passed through the sensor16. If the trailing end of the (N−1)th print medium has passed though the sensor16(YES in the determination), the process returns to S304; otherwise (NO in the determination), the process returns to S315.

In S317, the (N−1)th print medium is discharged. With this operation, printing on all the print media P is completed, and flowchart S30is terminated.

FIG.13is a flowchart showing the contents of wait calculation processing S70. Wait calculation processing is performed based on print data about the preceding print medium P and the succeeding print medium P.

The contents of wait calculation processing based on print data corresponding to the examples shown inFIGS.8A to9Cwill be described. A separating operation is started in the state inFIG.8A. A wait operation is executed in the state inFIG.9B. The separating operation in the state inFIG.9Cis ended. Assume that the relative positional relationship between the respective units at the start and end of a separating operation corresponds to the state shown in each ofFIGS.7A to7C.

In S701, a wait execution flag Fw and an exception processing flag Fr are initialized, and Fw=0 and Fr=0 (Fw=0 indicates that no wait operation is executed, and Fw=1 indicates that a wait operation is executed. Note that the exception processing flag Fr is the same as that described above).

In S702, a wait time Tw is calculated. This calculation is performed on the premise that the conveying speed V2 of the preceding print medium P has an upper limit V2max. First of all, a separation enable time Tmax is calculated. As described above,FIG.8Ashows the timing when a separating operation is started, more specifically, the timing when the trailing end of the preceding print medium P (the print medium P1 described above) passes through the conveyance roller10upon conveyance of the print medium P by the conveyance roller20. In this state, assume that the overlap amount between the preceding and succeeding print media P is W (seeFIG.7A), and the number of times of scanning that can be performed while the most downstream position of the nozzle71intermittently passes through the separation region Rh (the distance Lh of the separation region Rh) is a scan count Sc. Assume also that the required time per scan is a scan time Ts.

The separation enable time Tmax is calculated based on the overlap amount W, the scan count Sc, the scan time Ts, the distance Lh of the separation region Rh, and the conveying speed V1 of the succeeding print medium P.

Note that the conveying speed V1 of the succeeding print medium P is the conveying speed of the conveyance roller10in this embodiment.

FIG.14is a timing chart showing the contents of drive control on each mechanism at the time of the execution of a separating operation.FIG.14indicates that the conveyance rollers5and10are intermittently driven (conveying speed V1), and the carriage1is driven at a scanning speed Vc between the intermittent driving operations. Note that the driving of the carriage1is represented by a rectangular signal waveform inFIG.14, but the scan time Ts can include acceleration and deceleration times before and after each scanning operation.

The conveyance roller20is driven at the conveying speed V1 or V2 and is driven at the conveying speed V2 when executing a separating operation.

In addition, if YES is obtained in determining whether the most downstream position of the nozzle71is located in the separation region Rh, the corresponding signal is set at high level, whereas if NO is obtained in the determination, the corresponding signal set at low level. Likewise, if YES is obtained in determining whether the most downstream position of the nozzle71is located in the wait enable region Rw, the corresponding signal is set at high level, whereas if NO is obtained in the determination, the corresponding signal is set at low level.

Assuming that conveying speed V2 (of preceding print medium P)=V2max, the wait time Tw can be calculated based on the separation enable time Tmax as

Referring toFIG.13again, it is determined in S703whether wait time Tw>0. If Tw>0 (YES in the determination), the process advances to S704upon determining that a wait operation is required; otherwise (NO in the determination), it is determined that a wait operation is not required, and flowchart S70is terminated. The process then advances to S40inFIG.11A. In this state, wait execution flag Fw=0 (no wait operation is executed), and exception processing flag Fr=0 (no exception processing is executed).

In S704, the wait enable region Rw is calculated or specified based on the print data of the succeeding print medium P. As described above, a wait operation is performed in the wait enable region Rw that is a to-be-printed region (the above region Ky2 or the like) that is not continuous with a printed region (the above region Kd2) and is not the to-be-printed region Ky2 in a state before a printing operation (seeFIG.9A).

In S705, it is determined whether there is a region common to the wait enable region Rw and the separation region Rh. If there is a common region (YES in the determination), the process advances to S706upon determining that a wait operation can be executed. If there is no common region (NO in the determination), the process advances to S707upon determining that, although a wait operation is necessary, the wait operation is not executed to suppress or reduce a deterioration in printing quality.

In S706, wait execution flag Fw=1 (a wait operation is executed) is set. In S707, exception processing flag Fr=1 (exception processing is executed) is set. Thereafter, flowchart S70is terminated, and the process advances to S40inFIG.11A.

FIG.15is a flowchart showing control contents at the time of the execution of separating operation S50. In S501, it is determined whether wait execution flag Fw=1. If Fw=1 (a wait operation is executed) (YES in the determination), the process advances to S502; otherwise (NO in the determination), the process advances to S506.

In S502, it is determined whether the trailing end of the preceding print medium P has passed through the conveyance roller10(the upstream roller used in a separating operation). If the trailing end of the preceding print medium P has passed through the conveyance roller10(YES in the determination; for example, the state inFIG.8A), the process advances to S503; otherwise (NO in the determination), the process returns to S502.

In S503, the conveyance roller20(the downstream roller used in a separating operation) is driven at the conveying speed V2max to convey the preceding print medium P.

In S504, the driving of the conveyance roller10is suppressed or stopped during the wait time Tw calculated in S702at the timing when the most downstream position of the nozzle71is located in the region common to the regions Rw and Rh specified in S705(seeFIG.9B). This will separate the preceding print medium P from the succeeding print medium P at conveying speed V2=V2max, thereby reducing the overlap amount W and increasing the distance Dp′ (<Dp).

In S505, it is determined whether the distance Dp′ between the trailing end of the preceding print medium P and the leading end of the succeeding print medium P has reached the distance Dp (Dp′≥Dp). If Dp′≥Dp (YES in the determination or, for example, the state inFIG.9C), flowchart S50is terminated, and the process advances to S318inFIG.11B; otherwise (NO in the determination), the process returns to S505.

In S506(if Fw≠1/a wait operation is not executed, NO is determined in S501), the conveying speed V2 (≤V2max) of the preceding print medium P is calculated as

In S507, it is determined whether the trailing end of the preceding print medium P has passed through the conveyance roller10(the upstream roller used in a separating operation). If the trailing end of the preceding print medium P has passed through the conveyance roller10(YES in the determination), the process advances to S508; otherwise (NO in the determination), the process returns to S507.

In S508, the conveyance roller20(the downstream roller used in a separating operation) is driven at the conveying speed V2 (≤V2max) to convey the preceding print medium P. Thereafter, the process advances to S505.

<Example of Planned Printing Area)

Although the above embodiment has exemplified the to-be-printed region Ky2 shown inFIG.9A, it is possible to specify the regions Rw and Rh by another example following a similar procedure.FIGS.6A to16Dshow another example of the to-be-printed region Ky2 on the succeeding print medium P21. Assume that it is determined in S703that wait time Tw>0 (a wait operation is required).

In the example inFIG.16A, the region between the to-be-printed region Ky2 and an end of the print medium P2 is the wait enable region Rw, and its part is common to the separation region Rh. In such a case, a wait operation can be properly executed in the region common to the regions Rw and Rh.

The example inFIG.16Bdiffers from the example inFIG.16Ain that the separation region Rh is included in the wait enable region Rw. In such a case as well, a wait operation can be properly executed in the region common to the regions Rw and Rh.

In the example inFIG.16C, there are two wait enable regions Rw, which are included in the separation region Rh. In such a case as well, a wait operation can be properly executed in the region common to the regions Rw and Rh. That is, even if there are a plurality of wait enable regions Rw, a wait operation can be properly executed in the region common to the regions Rw and Rh.

In the above example, it is determined in S705that there is a region common to the wait enable region Rw and the separation region Rh, wait execution flag Fw=1 in S706, and a wait operation is executed in the separating operation in S50.

In the example inFIG.16D, almost the entire region of the print medium P2 is the to-be-printed region Ky2, and there is no wait enable region Rw. In such a case, it is determined in S705that there is no region common to the regions Rw and Rh, exception processing flag Fr=1 in S707. Accordingly, exception processing is executed in the overlap preparation operation in S40, and the above successive overlapped conveyance is not executed.

As described above, according to this embodiment, when a separating operation is performed to separate the preceding print medium P from the succeeding print medium P and cancel the overlap state, a wait operation is executed in the wait enable region Rw that is not the to-be-printed region Ky2 in a state before a printing operation. This substantially prevents the occurrence of a time difference until ink is dried between a given scanning operation and the next scanning operation by the printhead7in the same to-be-printed region Ky2. According to this embodiment, therefore, a wait operation during the execution of a separating operation is executed at the timing when the influence on the print quality is suppressed or reduced.

Note that in this embodiment, the conveyance of the succeeding print medium P is interrupted, and a scanning operation is also interrupted accordingly. However, another approximate operation may be performed as long as the succeeding print medium P is separated from the preceding print medium P.

For example, the conveying speed of the succeeding print medium P may be suppressed/reduced. In this case, the scanning operation interval of the printhead7with respect to the succeeding print medium P increases, and hence the print quality can be said to vary as in this embodiment. Therefore, the contents of the embodiment can also be applied to such a case.

The present invention may be implemented by supplying a program for implementing one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium and causing one or more processors in the computer of the system or apparatus to read out and execute the program. For example, the present invention may be implemented by a circuit (for example, an ASIC) which implements one or more functions.

In the above description, the printing apparatus9using the inkjet printing method has been described as an example. However, the printing method is not limited to this. Furthermore, the printing apparatus9may be a single function printer having only a printing function or may be a multi-function printer having a plurality of functions such as a printing function, a FAX function, and a scanner function. In addition, the printing apparatus9may be a manufacturing apparatus configured to manufacture, for example, a color filter, an electronic device, an optical device, a microstructure, or the like by a predetermined printing method.

Furthermore, “print” in this specification should be interpreted in a broader sense. Hence, the mode of “print” is irrespective of whether or not the target to be formed on a print medium is significant information such as a character or graphic pattern, and is also irrespective of whether the target is manifested in a way that can be perceived visually by humans.

“Print medium” should also be interpreted in a broader sense, like “print”. Hence, the concept of “print medium” can include not only paper used in general but also any materials capable of receiving ink, including fabrics, plastic films, metals, metal plates, glass, ceramics, resins, wood, and leathers.

“Ink” should also be interpreted in a broader sense, like “print”. Hence, the concept of “ink” can include not only a liquid that is applied to a print medium to form an image, a design, a pattern, or the like but also an incidental liquid that can be provided to process a print medium or process ink (for example, coagulate or insolubilize color materials in ink applied to a print medium).

In the above aspect, printing may be expressed as liquid discharging. Likewise, the printing apparatus9can also be expressed as the liquid discharging apparatus9. In addition, the printhead7can also be expressed as the liquid discharging head7. Furthermore, the print medium P may be reworded as a liquid discharging target, a medium, or the like.

In the embodiments, individual elements are named by expressions based on their main functions. However, the functions described in the embodiments may be sub-functions, and the expressions are not strictly limited. Furthermore, the expressions can be replaced with similar expressions. In the same vein, an expression “unit (portion)” can be replaced with an expression “tool”, “component”, “member”, “structure”, “assembly”, or the like. Alternatively, these may be omitted or added.

This application claims the benefit of Japanese Patent Application No. 2023-068019, filed on Apr. 18, 2023, which is hereby incorporated by reference herein in its entirety.