Patent Grant
11795024
The present invention relates to a printing apparatus having a sheet stacker on which ejected sheets are to be stacked.
Normally, in large-format ink-jet printers, a roll sheet is used as a print medium. The roll sheet is ejected after printing is performed, and the ejected print product is contained in a basket arranged in the lower portion of the printer. However, there is a limit to the storage capacity of the basket, and also, the next print product is stacked on a print product that has curled due to the curl of the roll sheet. Accordingly, it was not suitable for large-volume stacking due to problems such as susceptibility to damage and folds and difficulty in retrieval. In recent years, large-format stackers that deal with the above problem have appeared due to an increased demand for large-volume stacking.
Apparatuses that comprise, as such a type of stacker, an eject unit for ejecting a print product and stack the print product ejected by the eject unit onto a stacking tray positioned on the downstream side of the direction of conveyance of the eject unit are known. The stacking tray on which print products are to be stacked is positioned so as to be one level lower than the eject unit on the upstream side with respect to the direction of conveyance in order to stack a plurality of print products and, from there, is angled upward toward the downstream side with respect to the direction of conveyance. A print product conveyed by the eject unit drops onto the tray and is stacked once the trailing edge of the print product leaves the nip of the eject unit.
In a case where print products are to be stacked, if a print product ejected onto the stacking tray is curled, there are cases where that curled print product is pushed out from the stacking tray by a newly ejected print product. In order to deal with this, Japanese Patent Laid-Open No. 2016-69137, for example, by pressing the trailing edge of a print product with a pressing member, makes it possible to prevent the stacked print product, even if it is curled, from being pushed in the conveyance direction at the time of ejection of the next print product and to stack the print products in alignment.
However, with the configuration disclosed in Japanese Patent Laid-Open No. 2016-69137, in a case where printing is performed onto a sheet with poor ink fixability and that sheet is stacked onto the stacking tray, there are cases where, by pressing the trailing edge of the print product ejected onto the stacking tray, ink is transferred between sheets or onto the stacking tray. As a countermeasure to this problem, in order to prevent transferring of ink, it is conceived to set aside time to dry the ink from when a sheet is ejected onto the stacking tray to when the trailing edge is pressed. However, when time for drying is set aside as described above, in a case where a print product is curled or the like, there are cases where the trailing edge of the print product contacts a sheet eject roller, whereby the sheet is pushed out or is damaged.
The present invention is made in light of the problems described above, and provides a printing apparatus capable of improving the quality of a stacked sheet in a case where a printed sheet is stacked onto a stacking tray.
According to an aspect of the present invention, there is provided a printing apparatus comprising: a sheet eject tray; a movable guide arranged on an upstream side of the sheet eject tray in a direction of conveyance of a sheet and configured to be able to move to a protruding position at which the movable guide is protruded to a side of the sheet eject tray and a retracted position in which the movable guide is retracted to the upstream side from the protruding position; and a driving mechanism configured to cause the movable guide to move to the protruding position when a leading edge of a sheet is conveyed along the movable guide and cause the movable guide to move to the retracted position when a trailing edge of a sheet is conveyed along the movable guide, wherein the protruding position includes a first position at which the movable guide presses a sheet to the sheet eject tray and a second position between the first position and the retracted position.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, embodiments will be described in detail with reference to the attached drawings. Note, the following embodiments are not intended to limit the scope of the claimed invention. Multiple features are described in the embodiments, but limitation is not made to an invention that requires all such features, and multiple such features may be combined as appropriate. Furthermore, in the attached drawings, the same reference numerals are given to the same or similar configurations, and redundant description thereof is omitted.
The sheet 1 guided to the printing unit 400 is conveyed by a conveyance roller 14 in a conveyance direction indicated by an arrow F1. A nip roller (driven roller) 15 facing the conveyance roller 14 can be driven to rotate following the rotation of the conveyance roller 14. A cutter 21 is positioned on the downstream side of the printhead 18 in the conveyance direction (direction of the arrow F1) and cuts the sheet 1 by operating at the time of end of printing. Further on the downstream side of the cutter 21 is positioned a sheet eject switching flap 22 that can rotate in a direction of arrows E1 and E2 in the figure, and the position thereof is switched based on control by a CPU 201 (refer to
Next, the detailed configuration and operation of the upper face sheet eject unit in the printing apparatus 100 will be described.
The printing apparatus 100 of the present embodiment has movable guides 510 for pressing the trailing edge of the stacked sheet 1a and presses the trailing edge of the stacked sheet 1a during the sheet eject operation. The movable guides 510 temporarily retract from the stacked sheet 1a after the sheet 1 has been ejected onto the tray 29 and, before the next sheet is ejected, is made to protrude in order to press the trailing edge of the sheet 1 (stacked sheet 1a) again. A protruded movable guide 510 and the stacked sheet 1a contact at a contact point 511, and at this point, the stacked sheet 1a is pressed to the tray 29 by pressure. This makes it possible to prevent the stacked sheet 1a stacked on the tray 29 from curling and secure a path for ejecting the next sheet 1 to be ejected from the sheet eject roller 25 and the sheet eject nip roller 26. Also, at the same time, it is possible to prevent the deterioration of alignment performance in the tray 29 caused by the stacked sheet 1a being misaligned in the direction of movement of the sheet 1 due to friction when the stacked sheet 1a on the tray 29 and the sheet 1 being ejected contact.
The movable guides 510 are switched between a protruding state and a retracted state by the CPU 201 driving a movable guide driving motor 513. The upper face sheet eject path 502 is formed by an upper face sheet eject outer guide 502a and an upper face sheet eject inner guide 502b, and the movable guides 510 are positioned so as to approximately fit within the upper face sheet eject inner guide 502b.
As illustrated in
Next, the detailed configuration of an air blowing mechanism 530 will be described with reference to
Here, the number and position of air blowing fans are not limited; for example, configuration may be taken so as to send the air of a plurality of air blowing fans to one air blowing duct and then eject it from air blowing ports. In the present embodiment, the wind speed from the air blowing ports 533 is approximately 6.0 m/s directly below the air blowing ports 533; however, the wind speed is also not limited. If the sheet 1 floats in a stable manner, the wind speed does not have to be this. Also, the blowing speed is not limited to a constant value; for example, by making the operational duty of an air blowing fan changeable, a mechanism for changing an amount of blown air in accordance with the sheet type of sheet 1 or printing content may be arranged.
A third direction 536, which is a direction of the air blown from the air blowing port 533, is at an angle between a first direction 534 in which the sheet 1 is to be ejected from the sheet eject roller 25 and a second direction 535 in which the sheet 1 is to be stacked onto the tray 29.
The third direction 536 is a direction that connects the point at which the sheet 1 and the tray 29 contact and the air blowing port 533. Regarding the first direction 534 and the second direction 535, their extended lines intersect at a roughly 45-degree angle. However, the angle between the tray 29 (second direction 535) and a direction in which the sheet eject roller 25 conveys (first direction 534) are not limited to 45° and may be greater or lesser than 45°. In such a case, arranging a mechanism for adjusting the angle of the air blowing mechanism 530 makes it possible to adjust the third direction, whereby it becomes possible to blow air in the optimal direction in accordance with the type and length of the ejected sheet 1.
Next, the detailed configuration of a movable guide 510 will be described with reference to
The movable guide 510 functions as follows due to the flap portion 510a being movable as described above. In other words, the movable guide 510, when pressing the sheet 1 and the stacked sheet 1a, functions so as to press the curl from the top side of the curl of the sheet 1 and the stacked sheet 1a. Meanwhile, the movable guide 510, when retracting, functions such that the flap portion 510a rotates in the direction indicated by the arrow F2 due to the weight of the sheet 1 and the flap portion 510a is pulled out from the sheet 1 and the stacked sheet 1a.
The slide portion 510b can be moved in an arced trajectory in a direction indicated by an arrow S1 and a direction indicated by an arrow S2 with respect to a drive coupling portion 510c and is biased in the direction indicated by the arrow S1 by a biasing spring (elastic member) 510f. In the state of
A first protruding state in which there is one stacked sheet 1a on the tray 29 and a movable guide 510 is protruding until it causes the stacked sheet 1a to be in close contact with the tray 29 (first protruding position) is illustrated in
In
In the first protruding state of
In the present embodiment, the maximum number of stacked sheets on the tray 29 is set to 100 sheets, and the stacked sheets 1a of a thickness of approximately 10 mm is stacked on the tray 29. Accordingly, by setting the dimension of Lt to greater than or equal to 10 mm, it is possible to cause a state in which the stacked sheets 1a, regardless of the number of stacked sheets 1a, are not gripped by the movable guide 510.
In the second protruding state of
The switching of the position of the movable guide 510 illustrated in
Thus, in the present embodiment, a torque limiter 512a and a one-way clutch 512b are arranged in the driving unit 512. The torque limiter 512a will slip if a torque that is greater than or equal to a predetermined torque is applied; however, that slip torque value Tl is set to less than or equal to a maximum torque value Tmax at the time of driving of the movable guide driving motor 513. Also, the one-way clutch 512b arranged to be coupled with the torque limiter 512a, when rotating the movable guide shaft 514 in the direction indicated by the arrow P1, disconnects the drive coupling between the torque limiter 512a, the movable guide driving motor 513, and the movable guide shaft 514. Also, the one-way clutch 512b, when rotating the movable guide shaft 514 in the direction of the arrow P2, maintains the drive coupling between the torque limiter 512a, the movable guide driving motor 513, and the movable guide shaft 514. This makes it so that the load of the slip torque value Tl of the torque limiter 512a is not applied to the movable guide driving motor 513 when pressing the stacked sheet 1a by the protrusion of the movable guides 510, whereby it is possible to set the driving torque to a value that is less than the maximum torque value Tmax by the slip torque value Tl.
Here, a mechanical load torque value Tm for when the movable guide shaft 514 rotates is defined as a driving load torque necessary for purely driving the driving unit 512 excluding the slip torque value Tl of the torque limiter 512a and without the movable guides 510 pressing the sheet 1. Also, the holding torque value that the movable guide driving motor 513 has is defined as Td.
When all the torque values are converted as the torque value on the movable guide shaft 514, relational expressions such as the following are established.
P1 rotational direction: Tmax>Tn+Tm (1)
Suspended in protruding state: Tl+Tm+Td>Tn (2)
P2 rotational direction: Tmax>Tl+Tm (3)
From Expressions (1) and (3), it is understood that it is possible to set the pressing torque Tn and the slip torque Tl to be approximately the same. Also, it is understood that the mechanical load torque Tm and the holding torque Td of the motor necessary for when the movable guides 510 are suspended in a protruding state need only be set to a value lower than the pressing torque Tn.
Meanwhile, in a case where the torque limiter 512a is not provided, the slip torque Tl will be eliminated from Expression (2); accordingly, the mechanical load torque Tm and the holding torque Td of the motor need to be set so as to exceed the pressing torque Tn. In other words, if the pressing torque Tn increases, the mechanical load torque Tm and the holding torque Td of the motor need to be increased. If the mechanical load torque Tm is increased, the necessary maximum torque Tmax of the movable guide driving motor 513 will also increase based on Expressions (1) and (3). If the holding torque Td of the motor is increased, configuration in which power consumption of the motor increases (e.g., the movable guide driving motor 513 is excited also during suspension) will be necessary. In contrast to this, in the present embodiment, such a configuration is unnecessary, and it is possible to select the movable guide driving motor 513 provided with the smallest maximum torque value Tmax required.
Next, a sequence of an upper face sheet eject operation will be described.
At the time of reception of a print JOB, the sheet type and ink discharge concentration used for printing are detected (step S201) and it is determined whether or not a condition is that in which transfer of ink onto another sheet 1, the tray 29, and the like to be contacted would occur (step S202). For example, in accordance with ink fixability and ink discharging mode with reference to a table illustrated in
Then, based on the determination result in step S202, a sheet eject sequence A (step S203) or a sheet eject sequence B (step S204) is selected. Detailed operations of the sheet eject sequence A and the sheet eject sequence B will be described later. In a case where the sheet eject sequence B is selected, a waiting period Tc of the movable guides 510 to be described later is also decided. A sheet eject operation is concurrently performed with the print operation based on the selected sheet eject sequence.
When the sheet eject operation is completed, preparation for ejecting the next sheet is performed. Since the ejection of the next sheet is started in a state in which the movable guides 510 are pressing the trailing edge of the sheet 1 stacked on the tray 29, it is determined whether or not the leading edge position of the next sheet exceeds the sheet eject roller 25 based on the length of conveyance of the next sheet (step S205).
It is detected whether the movable guides 510 are in the first protruding state (step S206) and in a case where the movable guides 510 are not in the first protruding state, the conveyance of the sheet is suspended until the movable guides 510 transition to the first protruding state (step S207).
After the movable guides 510 press the trailing edge of the sheet 1 in the first protruding state, the next sheet is conveyed to the next position, which is an ink discharge position, (step S208) and ink discharge is performed by the printhead 18 (step S209).
Print completion determination is performed (step S210) and if printing has not been completed, steps S205 to S210 will be repeated.
After printing has been completed in step S210, the sheet is conveyed to the cutting position and a sheet cut is performed (step S211). After the sheet has been cut, in a case where the waiting period Tc is necessary at the time of protrusion of the movable guides 510 in the sheet eject sequence decided in step S202, counting of the waiting period Tc is performed (step S212) before the post-sheet-cut conveyance is resumed, and then sheet conveyance is resumed (step S213).
After sheet ejection has been completed, it is confirmed whether or not there remains an uncompleted print JOB (step S214). In a case where there remains an uncompleted print JOB, the processing returns to step S201 and in a case where there remains no uncompleted print JOB, printing is ended.
Next, the sheet eject sequence A selected in step S203 will be described with reference to
The sheet eject sequence A will be described. At the time of start of the sheet eject operation, a movable guide 510, as in
After the movable guide 510 enters the first protruding state, driving of the sheet eject roller 25 is started (step S2) and a sheet eject operation is performed. At the time of the sheet eject operation, the air blowing fan 531 for supplying air for drying the printing surface toward the printing surface from the vicinity of the sheet eject roller 25 is turned ON (step S3). In this state, completion of a cut after printing has been completed is awaited (step S4).
After detection of the trailing edge of the sheet 1 by an ejecting sheet sensor 520 on the upstream side of the sheet eject roller 25 (step S5) as in
After the sheet 1 has been ejected onto the tray 29, the driving of the sheet eject roller 25 is stopped (step S7) and the movable guide 510 is retracted. At this time, the movable guide 510 that has burrowed under the sheet 1 that has been ejected onto the tray 29 as in
After the movable guide 510 has been moved to the retracted position, the excitation of the movable guide driving motor 513, which operates the movable guide 510, is turned off (step S8). The sequence from steps S6 to S8 is a sequence for preventing the sheet 1, even if the trailing edge of the sheet 1 is curled, from being pushed out in the conveyance direction or becoming damaged due to the trailing edge of the sheet 1 contacting the sheet eject roller 25 at the time of retraction of the movable guide 510.
In the retracted state of the movable guide 510, it is confirmed whether there remains an uncompleted print JOB (step S9). In a case where there remains an uncompleted print JOB, it is confirmed whether to select the sheet eject sequence A or the sheet eject sequence B in the next printing (step S10). In a case where the sheet eject sequence A is selected, the processing returns to step S1 again and in a case where the sheet eject sequence B is selected, the processing transitions to step S101 of the sheet eject sequence B.
When moving the movable guide 510 from the retracted position to the first pressing position, the curled trailing edge of the sheet 1 is pushed by the movable guide 510 as in
In the present embodiment, in the phase of
In a case where there remains no uncompleted printing JOB in step S9, the sheet eject sequence A ends. In the sheet eject sequence A, the movable guide 510 is moved to the first protruding state again immediately after the movable guide 510 has entered the retracted state; accordingly, the period of time in which the sheet 1 and the stacked sheet 1a are not gripped by the movable guide 510 is short. Accordingly, there is an advantage that there is less opportunity for the stacked sheet 1a to be moved by external disturbance (vibration of the printing apparatus 100, shaking due to the user removing the stacked sheet 1a, force of airflow of an air conditioner or the like), whereby the series of operations is completed in a short amount of time.
Next, the sheet eject sequence B will be described. Steps S101 and S108, which are from the start of a sheet eject sequence until the movable guide is moved to the retracted state, is the same as steps S1 to S8 of the sheet eject sequence A.
In the retracted state of the movable guide 510, it is confirmed whether there remains an uncompleted print JOB (step S109).
In a case where there remains an uncompleted print JOB, the movable guide 510 is rotated to the second pressing position, which is the second protruding state, as in
In order to eject the next sheet, the sheet eject roller 25 is driven while the movable guide 510 is in the second pressing position (step S111), and then printing is resumed (step S112).
The movable guide 510 is made to wait in the second pressing position in order to prevent ink transfer (step S113) and is returned to the first pressing position after the waiting period Tc has elapsed (after it stops for a predetermined period of time). Note that the condition of drying of the ink depends on the type of paper; accordingly, the waiting period Tc is set in accordance with the type of paper.
It is confirmed whether the next printing selects the sheet eject sequence A or the sheet eject sequence B (step S114), in a case where the sheet eject sequence A is selected, the processing returns to step S1 of the sheet eject sequence A, and in a case where the sheet eject sequence B is selected, the processing returns to step S101.
In a case where there remains no uncompleted printing JOB in step S109, the sheet eject sequence B ends.
In the sheet eject sequence B, by setting aside time in which the sheet 1 and the stacked sheet 1a are not gripped by the movable guide 510, it is possible to dry the sheet 1 ejected immediately after printing. This makes it possible to prevent ink transfer between the sheets or onto the stacking tray. Meanwhile, the sheet 1 and the stacked sheet 1a are not gripped by the movable guide 510 until ink drying progresses; accordingly, there is more opportunity for the sheet to be moved by external disturbance than in the sheet eject sequence A. Also, the next sheet 1 cannot be ejected onto the tray 29 until ink drying is completed and the movable guide 510 enters a first pressing state; accordingly, the amount of time of a series of operations becomes longer.
As described above, by virtue of the present embodiment, in the sheet eject sequence A, it is possible to perform stacking of printed sheets in a stable manner and at high speed for sheets with good ink fixability. Also, in the sheet eject sequence B, stopping the movable guide at the second pressing position makes it possible, even in the sheets with poor ink fixability, to prevent ink transfer between the sheet or onto the stacking tray and to perform a stable stacking of sheets without causing damage to the sheets.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2020-166112, filed Sep. 30, 2020, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
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| 2020-166112 | Sep 2020 | JP | national |
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| Number | Date | Country | |
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