JP6164338B2 - Image recording device - Google Patents

Description

  The present invention relates to an image recording apparatus that discharges a sheet by an appropriate method according to rigidity.

  2. Description of the Related Art Conventionally, there is known an image recording apparatus that includes a conveyance unit that conveys a sheet and a recording unit that records an image on a sheet that is intermittently conveyed by the conveyance unit. The transport unit includes a first transport unit and a second transport unit that transport paper in the transport direction. The recording unit is disposed between the first transport unit and the second transport unit in the transport direction. Patent Document 1 describes an image recording apparatus that improves the throughput of image recording by transporting the preceding sheet and the succeeding sheet with a small interval.

  Specifically, the image recording apparatus described in Japanese Patent Application Laid-Open No. 2005-228561 includes cueing and intermittent conveyance for the succeeding sheet when image recording on the preceding sheet is completed and the trailing edge of the preceding sheet has passed the first conveying unit. To start. The preceding sheet is discharged intermittently (hereinafter referred to as “intermittent discharge”) by the second transport unit that rotates in conjunction with the cueing and intermittent transport of the subsequent sheet.

JP 2001-191601 A

  In the image recording apparatus having the above-described configuration, if a preceding sheet having low rigidity is intermittently discharged, the preceding sheet may buckle on the sheet discharge tray, which may prevent the subsequent sheet from being discharged. However, on the other hand, if intermittent discharge is not performed on the preceding sheet with high rigidity (that is, when the leading sheet starts to be cued after the discharge of the preceding sheet is completed), the throughput of image recording on a plurality of sheets decreases. Resulting in.

  The present invention has been made in view of the above circumstances, and an object thereof is to suppress buckling of a preceding sheet and a decrease in throughput by selecting an appropriate sheet discharge method according to the rigidity of the sheet. An object is to provide an image recording apparatus.

(1) An image recording apparatus according to the present invention includes a paper feed tray that supports a plurality of sheets, a conveyance roller that rotates forward and conveys sheets in the conveyance direction, and a downstream side of the conveyance direction from the conveyance rollers. And a recording unit that records an image on a sheet and a downstream side in the transport direction from the recording unit, and rotates forward with the forward rotation of the transport roller to transport the sheet in the transport direction. A discharge roller that is disposed downstream of the discharge roller in the transport direction, supports a sheet discharged by the discharge roller, and a control unit that controls recording of an image on the sheet. Prepare. The control unit is configured to feed the paper in the transport direction by feeding the paper supported by the paper feed tray to the transport roller and rotating the transport roller and the discharge roller forward. An intermittent recording process for recording an image on the recording unit with respect to a sheet conveyed by a predetermined line feed width and conveyed by a predetermined line feed width, and a rigidity determination process for determining the rigidity of the sheet are performed on the preceding sheet. Run. Then, when it is determined in the rigidity determination process that the rigidity of the preceding sheet is equal to or greater than a threshold value, the control unit finishes image recording on the preceding sheet and the trailing edge of the preceding sheet moves the transport roller. When the paper feeding process and the intermittent recording process for the succeeding sheet next to the preceding sheet are executed on the condition that the sheet has passed, and it is determined in the rigidity determining process that the rigidity of the preceding sheet is less than the threshold value In addition, prior to the intermittent recording process for the succeeding sheet, the discharging process for discharging the preceding sheet, on which image recording has been completed by rotating the conveying roller and the discharging roller forward without stopping, is discharged to the discharge tray. Run.

  According to the above configuration, the preceding paper whose rigidity is greater than or equal to the threshold value is intermittently discharged by the discharging roller that rotates in synchronization with the intermittent recording processing of the subsequent paper. As a result, the throughput of image recording is improved by the time required for the discharge process for the preceding paper. On the other hand, the preceding sheet whose rigidity is less than the threshold value is discharged by the discharging process executed prior to the intermittent recording process of the succeeding sheet. Thereby, a significant decrease in throughput due to buckling of the preceding paper on the paper discharge tray is suppressed.

(2) For example, the image recording apparatus includes a paper feed roller capable of forward rotation that feeds paper supported by the paper feed tray to the transport roller, a motor capable of forward rotation and reverse rotation, The feed roller is rotated forward by the reverse rotation of the motor, the transport roller is rotated reversely, the drive transmission to the discharge roller is released, and the transfer roller and the discharge roller are moved forward by the forward rotation of the motor. And a drive transmission mechanism for rotating and releasing the drive transmission to the paper feed roller. The control unit reversely rotates the motor in the paper feeding process, rotates the motor forward in the intermittent recording process and the discharge process, and the rigidity of the preceding sheet is less than the threshold in the rigidity determination process. If it is determined that there is, the discharge process is executed prior to the paper feed process for the subsequent sheet.

(3) Preferably, the control unit makes the rotation speed of the motor in the discharge process slower than the rotation speed of the motor in the intermittent recording process.

  The slower the rotation speed of the motor, the more stable the contact between the sheet and the discharge roller, that is, the sheet conveyance force by the discharge roller becomes stable. Further, the posture of the discharged paper becomes more stable as the rotation speed of the motor is decreased. Therefore, according to the above configuration, buckling of the preceding sheet on the sheet discharge tray can be further effectively suppressed.

(4) Preferably, the recording unit records an image by ejecting ink onto a sheet. In the rigidity determination process, the control unit determines that the rigidity of the sheet is less than the threshold when the amount of ink ejected on the sheet in the intermittent recording process is larger than the threshold ink amount.

  The stiffness of the paper is reduced by absorbing ink. Therefore, it is desirable to determine the rigidity of the paper according to the amount of ink ejected by the recording unit as in the above configuration. However, the criterion for determining the rigidity is not limited to the above example, and may be determined based on, for example, the direction of the fibers of the paper.

(5) Preferably, the control unit sets a first value for the threshold ink amount when the fiber direction of the paper is along the transport direction, and the threshold value when the fiber direction intersects the transport direction. A second value smaller than the first value is set as the ink amount.

  A paper with a horizontal line (that is, the direction of the fibers intersects the conveying direction) is likely to buckle as compared with a sheet with a vertical line (that is, the direction of the fibers follows the conveying direction). Therefore, as described above, in the rigidity determination process for the horizontal paper, it is desirable to lower the threshold ink amount than for the vertical paper.

(6) Preferably, the control unit compares the threshold ink amount with the amount of ink ejected to the central region of the paper in the transport direction in the rigidity determination process.

  The rigidity of the paper is greatly affected by the amount of ink that has landed on the central area of the paper. This is because when the paper is moved on the paper discharge tray, the movement of the front edge of the paper affects the rigidity of the central area of the paper. That is, if the rigidity of the central area of the paper is sufficiently large, the leading edge of the paper is pushed and moved by the central area of the paper. On the other hand, if the rigidity of the central area of the paper is small, the central area of the paper may buckle before the leading edge of the paper moves. Therefore, in the rigidity determination process, it is desirable to compare the ink amount that has landed on the central region with the threshold ink amount.

(7) Preferably, the image recording apparatus is capable of recording images on the front and back surfaces of the paper. The control unit determines a predetermined standby time when it is determined in the rigidity determination process that the rigidity of the preceding sheet is less than the threshold value and an image is recorded on both the front and back surfaces of the preceding sheet. It waits for execution of the discharge process for a time.

  The stiffness of the paper is further reduced by absorbing ink on both sides. Therefore, as described above, it is desirable that the discharging process for the paper on which the images are recorded on both sides is executed after waiting for the landed ink to dry.

(8) Preferably, the control unit records the image only on the front surface of the paper when the image is recorded on the front surface and the back surface of the paper according to the rotation amounts of the transport roller and the discharge roller in the discharge processing. More than you would.

  The frictional force between the ink adhering surface of the paper and the paper discharge tray is larger than the frictional force between the surface where no ink adheres and the paper discharge tray. That is, there is a possibility that the paper with ink attached to both the front and back surfaces will stop on the paper discharge tray and the rear end will not pass through the discharge roller. However, according to the above configuration, since the trailing edge of the low-rigidity sheet can pass through the discharge roller, the low-rigidity sheet can be reliably discharged.

(9) For example, the support surface of the paper discharge tray on which the discharged paper is supported is positioned vertically below the conveying direction with respect to the contact position of the discharge roller with the paper.

  The present invention has a particularly advantageous effect when applied to an image recording apparatus configured such that the sheet discharged from the discharge roller descends toward the support surface of the discharge tray as described above.

  According to the present invention, the preceding sheet having high rigidity is discharged in conjunction with the intermittent recording process of the succeeding sheet, and the preceding sheet having low rigidity is discharged before the intermittent recording process of the succeeding sheet. As described above, by selecting an appropriate paper discharge method according to the rigidity of the paper, it is possible to obtain an image recording apparatus that suppresses the buckling of the preceding paper and a decrease in throughput.

FIG. 1 is an external perspective view of the multifunction machine 10. FIG. 2 is a longitudinal sectional view schematically showing the internal structure of the printer unit 11. FIG. 3 is a block diagram illustrating the configuration of the multifunction machine 10. FIG. 4 is a flowchart of the image recording process. FIG. 5 is a diagram showing a state in which the paper feed process (S12) for the preceding paper 12A is executed. FIG. 6 is a diagram illustrating a state in which the discharge process (S16 or S21) for the preceding sheet 12A is performed. FIG. 7 is a diagram illustrating a state in which the additional conveyance process (S21) is necessary. FIG. 8 is a diagram illustrating a state in which the paper feeding process (S12) for the succeeding paper 12B is performed before the preceding paper 12A is discharged. FIG. 9 is a diagram illustrating a state in which the intermittent recording process (S13) for the succeeding paper 12B is executed from the state of FIG. FIG. 10 is a flowchart of image recording processing according to a modification.

  Hereinafter, embodiments of the present invention will be described. The embodiment described below is merely an example of the present invention, and it is needless to say that the embodiment of the present invention can be changed as appropriate without departing from the gist of the present invention. In the following description, the vertical direction 7 is defined with reference to the state in which the multifunction machine 10 is installed (the state in FIG. 1), and the side on which the opening 13 is provided is the front side (front side). A front-rear direction 8 is defined, and a left-right direction 9 is defined when the multifunction machine 10 is viewed from the front side (front side).

[Overall configuration of MFP 10]
The multifunction machine 10 (an example of the image recording apparatus of the present invention) is generally formed in a rectangular parallelepiped as shown in FIG. The multifunction machine 10 includes a printer unit 11 that records an image on a sheet 12 (see FIG. 2) using an inkjet recording method at the bottom. The multifunction machine 10 has various functions such as a facsimile function and a print function.

  As shown in FIG. 2, the printer unit 11 includes a paper feed unit 15, a paper feed tray 20, a paper discharge tray 21, a transport roller unit 54, a recording unit 24, a discharge roller unit 55, and a platen 42. And. The paper feed unit 15 picks up the paper 12 from the paper feed tray 20 and feeds it to the transport path 65. The transport roller unit 54 transports the paper 12 fed to the transport path 65 by the paper feed unit 15 in the transport direction 16. The recording unit 24 records an image on the paper 12 conveyed by the conveyance roller unit 54. The discharge roller unit 55 discharges the paper 12 on which the image is recorded by the recording unit 24 to the paper discharge tray 21. The platen 42 supports the paper 12 at a position facing the recording unit 24.

[Paper feed tray 20, paper discharge tray 21]
The paper feed tray 20 is inserted and removed in the front-rear direction 8 through an opening 13 formed in the front of the printer unit 11. The sheet feed tray 20 can support a plurality of sheets 12. The paper discharge tray 21 is provided on the upper side of the paper feed tray 20. The paper discharge tray 21 has a support surface 21 </ b> A that supports the paper 12 discharged by the discharge roller unit 55. The support surface 21 </ b> A forms the upper surface of the paper discharge tray 21, and is positioned below the vertical direction (that is, the vertical direction 7) from the nipping position of the paper 12 by the discharge roller portion 55.

[Paper Feeder 15]
As shown in FIG. 2, the paper feeding unit 15 is provided on the upper side of the paper feeding tray 20 mounted in the opening 13 of the printer unit 11. The paper feed unit 15 includes a paper feed roller 25, a paper feed arm 26, and a shaft 27. The paper feed roller 25 is rotatably provided on the front end side of the paper feed arm 26. The feed roller 25 is applied with a driving force from the transport motor 102 (see FIG. 3) and rotates in a direction (that is, forward rotation) in which the paper 12 is transported in the transport direction 16. The paper feed arm 26 is rotatably provided on a shaft 27 supported by the frame of the printer unit 11. The paper feed arm 26 is urged to rotate toward the paper feed tray 20 by its own weight or an elastic force by a spring or the like.

[Conveyance path 65]
As shown in FIG. 2, the conveyance path 65 indicates a space formed by an outer guide member 18 and an inner guide member 19 that are partially opposed to each other at a predetermined interval inside the printer unit 11. The conveyance path 65 extends from the rear end of the paper feed tray 20 to the rear side of the printer unit 11, and makes a U-turn while extending upward from the lower side on the rear side of the printer unit 11. It is a passage to 21. More specifically, the conveyance path 65 communicates with the sheet discharge tray 21 through the nipping position of the conveyance roller unit 54, the upper side of the platen 42, and the nipping position of the discharge roller unit 55. Note that the conveyance direction 16 of the paper 12 in the conveyance path 65 is indicated by a one-dot chain line arrow in FIG.

[Conveying roller unit 54]
As shown in FIG. 2, the transport roller unit 54 is provided on the downstream side in the transport direction 16 with respect to the paper feed unit 15 in the transport path 65 and on the upstream side in the transport direction 16 with respect to the recording unit 24 in the transport path 65. It has been. The conveyance roller unit 54 includes a conveyance roller 60 driven by the conveyance motor 102 and a pinch roller 61 that rotates with the rotation of the conveyance roller 60. The transport roller 60 and the pinch roller 61 sandwich the paper 12 and transport it in the transport direction 16.

  The transport roller 60 can rotate in the forward rotation (counterclockwise in the example of FIG. 2) and the reverse rotation (clockwise in the example of FIG. 2) for transporting the paper 12 in the transport direction 16. Switching between forward rotation and reverse rotation can be realized, for example, by reversing the rotation direction of the transport motor 102. Further, the pinch roller 61 shown in FIG. 2 rotates clockwise along with the forward conveying roller 60 and rotates counterclockwise along with the reverse rotating conveying roller 60.

[Discharge roller section 55]
As shown in FIG. 2, the discharge roller unit 55 is provided on the downstream side of the transport direction 16 with respect to the recording unit 24 in the transport path 65. The discharge roller unit 55 includes a discharge roller 62 driven by the conveyance motor 102 and a spur 63 that rotates with the rotation of the discharge roller 62. The discharge roller 62 can rotate in the forward rotation (in the example of FIG. 2, clockwise) that transports the paper 12 in the transport direction 16. Further, the spur 63 shown in FIG. 2 rotates counterclockwise with the discharge roller 62 rotating in the forward direction. As a result, the discharge roller 62 and the spur 63 sandwich the paper 12 and transport it in the transport direction 16. The holding position of the paper 12 by the discharge roller 62 and the spur 63 (that is, the contact position of the discharge roller 62 with the paper 12) is located above the support surface 21A of the discharge tray 21 in the vertical direction.

[Drive transmission mechanism 104]
Further, as shown in FIG. 3, the driving force of the transport motor 102 is transmitted to the paper feed roller 25, the transport roller 60, and the discharge roller 62 by the drive transmission mechanism 104. The drive transmission mechanism 104 is configured by combining all or part of a gear, a pulley, an endless annular belt, a planetary gear mechanism (pendulum gear mechanism), a one-way clutch, and the like. The drive transmission mechanism 104 forwardly rotates the transport roller 60 and the discharge roller 62 by the forward rotation of the transport motor 102 and releases the drive transmission to the paper feed roller 25. Further, the drive transmission mechanism 104 rotates the paper feed roller 25 forward, reversely rotates the transport roller 60, and cancels the drive transmission to the discharge roller 62 by reverse rotation of the transport motor 102.

  “Release the drive transmission to the paper feed roller 25” means that the driving force of the transport motor 102 is not transmitted to the paper feed roller 25. Specifically, a one-way clutch is disposed on the transmission path of the driving force between the conveyance motor 102 and the paper feeding roller 25, and the driving force of the conveying motor 102 that rotates in the reverse direction is transmitted to the paper feeding roller 25 to rotate forward. What is necessary is just to prevent the driving force of the transport motor 102 from being transmitted to the paper feed roller 25. Moreover, said structure is realizable also by arrange | positioning a pendulum gear mechanism and an electromagnetic clutch mechanism instead of a one-way clutch. Accordingly, the paper feed roller 25 when the transport motor 102 is rotating forward is brought into contact with the paper 12 transported in the transport direction 16 by the transport roller unit 54.

  Similarly, “releasing drive transmission to the discharge roller 62” means that the driving force of the conveyance motor 102 is not transmitted to the discharge roller 62, and is a one-way clutch, pendulum gear mechanism, or electromagnetic clutch mechanism. Are arranged in the transmission path of the driving force. As a result, the discharge roller 62 when the transport motor 102 rotates in the forward direction rotates forward together with the transport roller portion 54, and the discharge roller 62 stops when the transport motor 102 rotates in the reverse direction.

[Platen 42]
As shown in FIG. 2, the platen 42 is provided between the transport roller unit 54 and the discharge roller unit 55 in the transport direction 16. The platen 42 is disposed on the lower side of the conveyance path 65 so as to face the recording unit 24, and supports the sheet 12 conveyed on the conveyance path 65 from the lower side.

[Recording unit 24]
As shown in FIG. 2, the recording unit 24 is provided between the conveyance roller unit 54 and the discharge roller unit 55 in the conveyance direction 16. Further, the recording unit 24 is disposed on the upper side of the conveyance path 65 so as to face the platen 42. The recording unit 24 includes a carriage 23 that can move in the left-right direction 9 along the guide rail, a recording head 39 mounted on the carriage 23, and a nozzle 40 formed on the lower surface of the recording head 39.

  The carriage 23 receives the driving force from the carriage motor 103 and moves in the left-right direction 9. Switching of the movement direction of the carriage 23 can be realized, for example, by reversing the rotation direction of the carriage motor 103 (see FIG. 3). The nozzle 40 discharges the ink supplied from the ink cartridge as fine ink droplets. That is, the recording unit 24 ejects ink droplets from the nozzles 40 toward the paper 12 supported by the platen 42 in the process in which the carriage 23 moves in the left-right direction 9. As a result, an image is recorded on the paper 12.

[Registration sensor 160]
As shown in FIG. 2, a known registration sensor 160 is provided on the upstream side of the conveyance direction 16 with respect to the conveyance roller portion 54 of the conveyance path 65. The registration sensor 160 is a sensor for detecting whether or not the sheet 12 is present at the installation position of the registration sensor 160 (hereinafter referred to as “detection position”). The registration sensor 160 outputs a low level signal that is a detection signal (that is, “signal whose signal level is less than the threshold”) to the control unit 130 described later on condition that the sheet 12 is present at the detection position. On the other hand, the registration sensor 160 outputs a high level signal that is a detection signal (that is, “signal having a signal level equal to or greater than the threshold”) to the control unit 130 on condition that the sheet 12 is not present at the detection position.

[Rotary encoder 170]
Further, as illustrated in FIG. 3, the multifunction machine 10 includes a known rotary encoder 170 that generates a pulse signal according to the rotation of the transport roller 60 (in other words, the rotation of the transport motor 102). The rotary encoder 170 includes an encoder disk and an optical sensor. The encoder disk rotates with the rotation of the transport roller 60. The optical sensor reads the rotating encoder disk to generate a pulse signal, and outputs the generated pulse signal to the control unit 130.

[Control unit 130]
As shown in FIG. 3, the control unit 130 includes a CPU 131, a ROM 132, a RAM 133, an EEPROM 134, and an ASIC 135, which are connected by an internal bus 137. The ROM 132 stores a program for the CPU 131 to control various operations. The RAM 133 is used as a storage area for temporarily recording data and signals used when the CPU 131 executes the program, or as a work area for data processing. The EEPROM 134 stores settings, flags, and the like that should be retained even after the power is turned off.

  A transport motor 102 and a carriage motor 103 are connected to the ASIC 135. The ASIC 135 acquires a drive signal for rotating each motor from the CPU 131, and outputs a drive current corresponding to the drive signal to each motor. Each motor rotates forward or backward by a drive current from the ASIC 135. For example, the control unit 130 controls driving of the transport motor 102 to rotate each roller. Further, the control unit 130 controls the drive of the carriage motor 103 to reciprocate the carriage 23. Further, the control unit 130 controls the recording head 39 to eject ink from the nozzles 40.

  In addition, a registration sensor 160 and a rotary encoder 170 are connected to the ASIC 135. The control unit 130 detects the position of the paper 12 based on the detection signal output from the registration sensor 160 and the pulse signal output from the rotary encoder 170. More specifically, the ASIC 135 counts the pulse signal acquired from the rotary encoder 170 from the time when the low level signal is acquired from the registration sensor 160 (or changed from the low level signal to the high level signal). The ASIC 135 detects the position of the front end (or the rear end) of the paper 12 based on the number of counted pulse signals.

[Image recording processing]
With reference to FIGS. 4 to 9, image recording processing by the multifunction machine 10 will be described. Hereinafter, an example in which an image is recorded on the preceding sheet 12A supported on the sheet feeding tray 20 and the succeeding sheet 12B next to the preceding sheet 12A will be described. This image recording process is executed by the CPU 131 of the control unit 130. The following processes may be executed by the CPU 131 reading out and executing a program stored in the ROM 132, or may be realized by a hardware circuit mounted on the control unit 130.

  The control unit 130 executes the image recording process shown in FIG. 4 on the condition that an image recording instruction has been acquired from the user. The acquisition destination of the image recording instruction is not particularly limited. For example, the image recording instruction may be acquired through an operation panel provided in the multifunction machine 10 or may be acquired from an external device through a communication network. The image recording instruction is an instruction for causing the controller 130 to control each roller, the carriage 23, and the recording head 39 to perform image recording on the preceding sheet 12A and the succeeding sheet 12B. Further, the image recording instruction includes the number of pages on which image recording is performed, image data recorded on each page, and the like. Further, the image recording instruction may include fiber information regarding the fiber direction of the paper 12 on which an image is to be recorded (that is, information specifying whether the paper 12 is a vertical eye or a horizontal eye).

  First, the control unit 130 executes a paper feed process for feeding the paper 12 supported by the paper feed tray 20 to the transport path 65 (S12). Specifically, the controller 130 reversely rotates the transport motor 102 to rotate the paper feed roller 25 in the forward direction and reversely rotate the transport roller 60 to release the transmission of the driving force to the discharge roller 62. As a result, the paper feed roller 25 sends the preceding paper 12 </ b> A positioned at the top of the plurality of papers 12 supported by the paper feed tray 20 to the transport path 65. Further, the control unit 130 starts a counting process for counting the pulse signals output from the rotary encoder 170. The count process is continued in parallel with each process shown in FIG. 4 until the image recording process shown in FIG. 4 is completed (RETURN).

  The control unit 130 continues the paper feeding process (S12) until the number of pulse signals from the time when the low level signal is acquired from the registration sensor 160 reaches a predetermined threshold value. The predetermined threshold value is the conveyance required for the leading edge of the preceding sheet 12A that has reached the position of the registration sensor 160 (referred to as “the downstream end of the conveyance direction 16”, the same applies hereinafter) to reach the conveyance roller unit 54. It is the number of pulse signals corresponding to the distance. That is, the predetermined threshold is the number of pulse signals corresponding to the rotation amount of the paper feed roller 25 (in other words, the rotation amount of the conveyance motor 102) necessary for conveying the paper 12 by the above-described conveyance distance. As a result, as shown in FIG. 5, the leading edge of the preceding paper 12 </ b> A reaches the transport roller portion 54. Further, the leading edge of the preceding paper 12A is corrected by the contact of the leading end of the preceding paper 12A with the transport roller portion 54 that is rotating in the reverse direction.

  Next, when the leading edge of the sheet 12 reaches the transport roller unit 54, the control unit 130 performs an intermittent recording process on the preceding sheet 12A (S13). The intermittent recording process is a process in which the preceding sheet 12A is conveyed in the conveying direction 16 by the conveying roller unit 54 and the discharge roller unit 55, and an image is recorded on the recording unit 24 with respect to the preceding sheet 12A that has been conveyed and is stationary. is there. The control unit 130 causes the transport roller unit 54 and the discharge roller unit 55 to transport the preceding paper 12A by rotating the transport motor 102 forward.

  Further, in the first intermittent recording process for the preceding paper 12A, the control unit 130 moves the transport roller unit 54 and the discharge roller unit 55 to a position where the area on the preceding paper 12A where the image is first recorded faces the recording head 39. Then, the preceding paper 12A is conveyed. On the other hand, in the second and subsequent intermittent recording processes for the preceding sheet 12A, the control unit 130 causes the conveying roller unit 54 and the discharge roller unit 55 to convey the preceding sheet 12A by a predetermined line feed width.

  The control unit 130 repeatedly executes the intermittent recording process (S13) until the image recording on the preceding sheet 12A is completed (S14: Yes). When the image recording on the preceding paper 12A is completed (S14: Yes), the control unit 130 determines whether or not there is the subsequent paper 12B (S15). For example, the control unit 130 counts the number of pages on which image recording has been performed since the image recording instruction is acquired, and when the counted number of pages reaches the number of pages included in the image recording instruction, It is determined that there is no subsequent sheet 12B (S15: No).

  If it is determined that the succeeding sheet 12B does not exist (S15: No), the control unit 130 executes a discharge process (S16) for discharging the preceding sheet 12A for which image recording has been completed to the discharge tray 21, and performs the image recording process. finish. Specifically, the control unit 130 rotates the transport motor 102 in the forward direction without stopping halfway until the preceding paper 12A is discharged to the paper discharge tray 21. As a result, the preceding paper 12A is transported to the paper discharge tray 21 by the transport roller portion 54 and the discharge roller portion 55, as shown in FIG. Note that the control unit 130 performs forward rotation of the transport motor 102 and the discharge roller 62 (that is, forward rotation of the transport motor 102) until the trailing edge of the preceding paper 12A passes the discharge roller unit 55 in the discharge process of step S16. ) Continue without stopping on the way.

  Here, when the discharge process (S16) is executed in a state where the leading end side of the preceding paper 12A is caught on the support surface 21A of the discharge tray 21, the center portion is raised as shown by a one-dot chain line in FIG. There is a possibility that the preceding paper 12A is curved (hereinafter, this state is expressed as “buckling”) and is not completely discharged. The buckling of the preceding paper 12A is caused by the rigidity of the preceding paper 12A with respect to the frictional force between the preceding paper 12A and the support surface 21A (or another paper 12 supported by the support surface 21A). This is likely to occur when the following is low. Therefore, it is desirable that the control unit 130 makes the rotation speed of the conveyance motor 102 in the discharge process (S16) slower than the rotation speed of the conveyance motor 102 in the intermittent recording process (S13).

  On the other hand, when the counted number of pages is less than the number of pages included in the image recording instruction, the control unit 130 determines that the subsequent sheet 12B exists (S15: Yes). When the succeeding sheet 12B exists (S15: Yes), the control unit 130 executes a rigidity determination process for determining the rigidity of the preceding sheet 12A (S17). Specifically, the control unit 130 calculates the amount of ink ejected to the preceding paper 12A in the intermittent recording process (S13) (hereinafter referred to as “ejection ink amount”) and a predetermined threshold ink amount. Compare. Then, the control unit 130 determines that the rigidity of the preceding paper 12A is less than the threshold (S18: No) when the amount of ejected ink is larger than the threshold ink amount, and determines that the preceding sheet 12A does not exceed the threshold ink amount when the ejected ink amount is equal to or less than the threshold ink amount. It is determined that the stiffness is equal to or greater than the threshold (S18: Yes).

  If the rigidity of the preceding sheet 12A is less than the threshold (S18: No), the control unit 130 executes a discharge process for the preceding sheet 12A (S19). Since the discharge process in step S19 is common to step S16, the description thereof will be omitted.

  On the other hand, when the rigidity of the preceding sheet 12A is equal to or greater than the threshold value (S18: Yes), the control unit 130 indicates the position of the rear end of the preceding sheet 12A (refers to the “upstream end of the conveying direction 16”, the same applies hereinafter). More specifically, it is determined whether or not the trailing edge of the preceding paper 12A has passed the transport roller unit 54 (S20). Specifically, the control unit 130 is based on the condition that the number of pulse signals counted from the time when the detection signal output from the registration sensor 160 changes from a low level signal to a high level signal exceeds a predetermined threshold. It is determined that the trailing edge of the preceding paper 12A has passed the transport roller unit 54 (S20: Yes).

  Then, as shown in FIG. 7, when the trailing edge of the preceding paper 12A has not yet passed the transport roller unit 54 (S20: No), the control unit 130 sets the trailing edge of the preceding paper 12A to the transport roller unit 54. An additional transport process for reaching the downstream side in the transport direction 16 is executed (S21). Specifically, the control unit 130 rotates the transport motor 102 in the forward direction until the trailing edge of the preceding paper 12 </ b> A passes through the transport roller unit 54. The position of the trailing edge of the preceding paper 12A is determined by a combination of a detection signal output from the registration sensor 160 and a pulse signal output from the rotary encoder 170. On the other hand, when the trailing edge of the preceding paper 12A has already passed the transport roller unit 54 (S20: Yes), the additional transport process (S21) is skipped.

  Next, the control unit 130 executes image recording on the subsequent sheet 12B (S12 to S16). Note that the image recording process for the succeeding sheet 12B in the case where the preceding sheet 12A has already been discharged to the sheet discharge tray 21 in step S19 is common to the image recording process for the preceding sheet 12A, and thus the description thereof will be omitted. On the other hand, the preceding paper 12A for which the discharge process has not been executed is not sandwiched between the transport roller portions 54 (that is, the rear end of the preceding paper 12A passes through the transport roller portion 54), and the discharge roller portion 55. It is in a state of being sandwiched between.

  First, the control unit 130 executes a paper feed process for the subsequent paper 12B (S12). As a result, as shown in FIG. 8, in the state where the preceding paper 12A is sandwiched between the discharge roller portions 55 (that is, the state where the preceding paper 12A is not completely discharged), the leading edge of the succeeding paper 12B is the conveyance roller portion. 54 is reached.

  Next, the control unit 130 executes an intermittent recording process for the subsequent sheet 12B (S13). When the first intermittent recording process is performed on the succeeding sheet 12B from the state of FIG. 8, as shown in FIG. 9, the succeeding sheet 12B has an area on the succeeding sheet 12B where an image is first recorded as a recording head. It is transported in the transport direction 16 until it reaches a position facing 39. Further, since the discharge roller 62 is also rotated forward by rotating the transport motor 102 forward, the preceding sheet 12A is transported in the transport direction 16 in the intermittent recording process. That is, the preceding sheet 12A is intermittently discharged in the process of performing the one or more intermittent recording processes (S13) and the discharging process (S16) on the subsequent sheet 12B.

[Operational effects of this embodiment]
According to the present embodiment, the preceding sheet 12A with a low risk of buckling (that is, the rigidity is equal to or greater than a threshold value) rotates forward in conjunction with the intermittent recording process (S13) and the discharge process (S16) of the subsequent sheet 12B. The paper is intermittently discharged by the discharge roller portion 55. Thereby, the throughput of the image recording process is improved by the time of the discharge process (S19) for the preceding paper 12A. On the other hand, the preceding sheet 12A having a high risk of buckling (that is, the rigidity is less than the threshold) is discharged by the discharging process (S19) executed prior to the intermittent recording process (S13) of the succeeding sheet 12B.

  When the preceding sheet 12A is intermittently discharged, the conveyance and the rest of the preceding sheet 12A are repeated on the support surface 21A of the sheet discharge tray 21. Here, when the transport of the preceding paper 12A in the stationary state is started, the discharge roller unit 55 causes the preceding paper 12A to be transported in the transport direction 16 with a force larger than the static friction force generated between the preceding paper 12A and the support surface 21A. It is necessary to press. On the other hand, when the preceding sheet 12A is continuously conveyed, the discharge roller unit 55 may push the preceding sheet 12A in the conveying direction 16 with a force larger than the dynamic friction force generated between the preceding sheet 12A and the support surface 21A. . The static friction force is generally larger than the dynamic friction force. In other words, the preceding paper 12A that is intermittently discharged may be buckled without being able to withstand the force exceeding the static friction force. On the other hand, the preceding paper 12A discharged without stopping in the middle only needs to be able to withstand the dynamic friction force smaller than the static friction force, so the possibility of buckling is reduced. Thereby, a significant decrease in throughput due to buckling of the preceding paper 12A on the paper discharge tray 21 is suppressed.

  Further, in the discharge process in the present embodiment, the rotation speed of the transport motor 102 is made slower than in the intermittent recording process. As the rotation speed of the transport motor 102 is decreased, the contact between the paper 12 and the discharge roller 62 is stabilized, that is, the transport force of the paper 12 by the discharge roller 62 is stabilized. Further, as the rotation speed of the transport motor 102 is decreased, the posture of the discharged paper 12 is stabilized. As a result, the buckling of the preceding paper 12A on the paper discharge tray 21 can be more effectively suppressed.

  Note that the rigidity of the paper 12 is reduced by the ink being absorbed by the paper 12. Therefore, it is desirable to determine the rigidity of the paper 12 according to the amount of ink ejected in the intermittent recording process (S13). Further, the threshold ink amount used in the stiffness determination process (S17) may be determined, for example, in relation to the probability of occurrence of buckling of the paper 12. That is, the probability of occurrence of buckling of the paper 12 discharged to the paper discharge tray 21 is calculated for each ink discharge amount through experiments, simulations, and the like, and the largest ink discharge amount is within a range where the risk of buckling is small. The amount of ink may be used. As an example, the threshold ink amount can be 0.64 ml (40 pl of 16 pl ink droplets).

  Further, the probability of occurrence of buckling varies depending on whether the paper 12 is vertical or horizontal. Therefore, the threshold ink amount can be changed depending on the direction of the fibers constituting the paper 12. For example, a first value is set for the threshold ink amount when the fiber direction of the paper 12 is along the transport direction 16 (that is, a vertical eye), and the threshold value is set when the fiber direction intersects the transport direction 16 (that is, a horizontal eye). A second value smaller than the first value may be set as the ink amount. As an example, the first value may be 0.64 ml as described above, and the second value may be half of the first value (ie, 0.32 ml). Note that the control unit 130 may set the threshold ink amount as described above from the fiber information included in the image recording instruction. The control unit 130 may uniquely set the threshold ink amount to either the first value or the second value based on the size of the paper 12 on which the image is to be recorded.

  Further, the rigidity of the paper 12 is particularly greatly affected by the amount of ink that has landed on the central region of the paper 12. This is because the leading edge of the paper 12 moving on the paper discharge tray 21 is pushed in the transport direction 16 by the rigidity of the central region of the paper 12. That is, if the amount of ink in the central region increases (larger than the threshold ink amount), the rigidity of the central region decreases due to ink permeation, and the central region may buckle before the leading edge of the paper 12 moves. There is. Therefore, the amount of ink to be compared in the rigidity determination process (S17) may be limited to the amount of ink ejected to the central region in the transport direction 16 on the recording surface of the preceding paper 12A. Alternatively, the recording surface of the preceding paper 12A is divided into a leading edge region near the leading edge of the preceding paper 12A, the above-described central region, and a trailing edge region near the trailing edge of the preceding paper 12A, and the amount of ink ejected on each is weighted. The amount of ejected ink may be calculated by addition. In other words, the weighting coefficient in the central area may be made larger than that in the front end area and the rear end area. However, the method of calculating the ejection ink amount is not limited to the above example, and all the ink amounts ejected onto the preceding paper 12A may be simply added.

  As an example, in the conveyance direction 16, a range of 60 mm from the front end of the paper 12 can be a front end region, a range of 60 mm from the rear end can be a rear end region, and a region between the front end region and the rear end region can be a central region. . That is, the central area when A4 paper (210 × 297 mm) is transported horizontally is 90 mm, the central area when A4 paper is transported vertically is 177 mm, and A3 paper (297 × 420 mm) is transported vertically. The central area is 300 mm. Note that the length of 60 mm, which is the length of the leading end region and the trailing end region, corresponds to the interval between the nipping positions of the paper 12 in the transport roller portion 54 and the discharge roller portion 55, respectively.

  However, the criterion for determining the rigidity is not limited to the above example. For example, the determination may be made only by the fiber orientation of the paper 12. That is, the rigidity of the vertical paper 12 may be determined to be equal to or greater than the threshold, and the rigidity of the horizontal paper 12 may be determined to be less than the threshold. The fiber direction of the paper 12 may be included in the image recording instruction. Alternatively, the rigidity of the paper 12 on which the image is recorded only on the front surface may be determined to be equal to or greater than the threshold value, and the rigidity of the paper 12 on which the image is recorded on both the front surface and the back surface may be determined to be less than the threshold value. A configuration for recording images on both sides of the paper 12 will be described later.

  The image recording process according to the present embodiment is particularly advantageous when applied to the multifunction machine 10 configured such that the paper 12 discharged from the discharge roller unit 55 descends toward the support surface 21A of the paper discharge tray 21, for example. Has an effect. However, the present invention is not limited to the above shape. For example, the present invention is also effective when the support surface 21A of the paper discharge tray 21 is inclined upward from the upstream side to the downstream side in the transport direction 16. Furthermore, the present invention is particularly effective for the multi-function peripheral 10 that records an image on a large-size sheet 12 (that is, a sheet 12 that takes time to discharge).

  In the above embodiment, the example in which the paper feed roller 25, the transport roller 60, and the discharge roller 62 are driven by the common transport motor 102 has been described, but the present invention is not limited to this. That is, a motor for driving the paper feed roller 25 and a motor for driving the transport roller 60 and the discharge roller 62 (transport motor 102) may be prepared. In this case, while the control unit 130 is executing the discharge process (S19) of the preceding paper 12A, the control unit 130 drives the paper feed motor to feed the subsequent paper 12B to the paper feed roller 25. The process (S12) may be executed. That is, the control unit 130 may execute the discharge process (S19) of the preceding sheet 12A and the sheet feeding process (S12) of the succeeding sheet in parallel. The control unit 130 also feeds the succeeding sheet 12B (S12) on the condition that the image recording of the preceding sheet 12A has been completed (S14) and the rear end of the preceding sheet 12A has passed the transport roller unit 54. May start.

  In the above embodiment, the image recording process for the preceding paper 12A and the succeeding paper 12B supported by the paper feed tray 20 has been described. However, the present invention is not limited to this. For example, the present invention relates to the preceding sheet 12A and the succeeding sheet 12B supported by the manual feed tray (another example of the sheet feeding tray according to the present invention) located on the upstream side in the conveying direction 16 with respect to the conveying roller unit 54 and the registration sensor 160. It can also be applied to image recording processing. Note that the paper feed process (S12) in this case corresponds to a process of pushing up the leading end of the paper 12 in order to cause the paper 12 supported by the manual feed tray to reach the transport roller unit 54.

  Furthermore, in the above-described embodiment, the example of the multifunction machine 10 including the inkjet recording type printer unit 11 has been described as an example of the image recording apparatus, but the present invention is not limited to this. For example, the present invention may be applied to a laser recording type printer.

[Other Embodiments]
In the above embodiment, the example of the multifunction machine 10 that records an image only on one side of the paper 12 (hereinafter referred to as “front surface”) has been described, but the present invention is not limited to this and the paper is not limited thereto. The present invention can also be applied to an image recording apparatus having a double-sided printing function for recording an image on the other surface (hereinafter referred to as “back surface”). The image recording apparatus having a duplex printing function further includes a reverse conveyance path, a reverse roller unit, and a re-conveyance roller unit in addition to the configuration of FIG.

  The reverse conveyance path branches from the conveyance path 65 at a branch position downstream in the conveyance direction 16 from the discharge roller portion 55 and merges with the conveyance path 65 at a merge position upstream from the registration sensor 160 in the conveyance direction 16. It is. That is, the paper 12 on which the image is recorded on the back surface is conveyed in the direction from the branch position to the merge position on the reverse conveyance path.

  The reverse roller portion is disposed on the downstream side in the transport direction 16 from the discharge roller portion 55 and the branch position in the transport path 65. The reversing roller unit can perform forward rotation for transporting the paper 12 in the transport direction 16 and discharging it to the paper discharge tray 21 and reverse rotation for transporting the paper 12 to the reverse transport path through the branch position. Specifically, the reversing roller unit is rotated forward by applying a driving force from the transport motor 102 that rotates in the forward direction, and rotates reversely by receiving driving force from the transport motor 102 that rotates in the reverse direction.

  The re-conveying roller unit is provided in the reverse conveying path. The re-conveying roller unit is capable of normal rotation for conveying the paper 12 on the reverse conveying path toward the merging position. Specifically, the re-conveying roller unit is rotated forward by being applied with a driving force from the conveying motor 102 that rotates forward and backward.

  In the image recording apparatus having the above configuration, for example, it is desirable to execute an image recording process as shown in FIG. The steps common to the image recording process shown in FIG. 4 are denoted by the same reference numerals, detailed description thereof is omitted, and differences will be mainly described.

  In the image recording process shown in FIG. 10, after the image recording on the front surface of the paper 12 is completed (S14: Yes), the control unit 130 determines whether image recording on the back surface of the paper 12 is necessary (S22). ). When image recording on the back surface is necessary (S22: Yes), the control unit 130 performs a reversing process in which the paper 12 is reversed and conveyed to the position of the recording unit 24 again (S23). Note that the control unit 130 determines that image recording on the back surface is necessary in step S22, for example, when the image recording instruction includes information indicating that the back surface printing is to be performed.

  Specifically, the control unit 130 rotates the transport motor 102 forward until the rear end of the paper 12 passes through the branch position. Next, the control unit 130 reversely rotates the transport motor 102 on the condition that the rear end of the paper 12 has passed the branch position, thereby transporting the paper 12 to the reverse roller unit and the re-transport roller unit through the reverse transport path. The roller part 54 is conveyed. Then, the control unit 130 performs an intermittent recording process (S13) on the back surface of the paper 12 on the condition that the tip of the reversed paper 12 has reached the transport roller unit 54. Note that the position of the leading or trailing edge of the paper 12 is determined by a combination of a detection signal output from the registration sensor 160 and a pulse signal output from the rotary encoder 170.

  Further, when it is determined that the rigidity of the sheet 12 is less than the threshold (S18: No), the control unit 130 determines whether an image is recorded on the back surface of the sheet 12 (S24). When an image is recorded on the back surface of the paper 12 (S24: Yes), the control unit 130 executes a standby process for delaying the execution of the discharge process (S19) (S25). Specifically, the control unit 130 stops the conveyance motor 102 for a predetermined time. The stop time of the conveyance motor 102 may be a fixed value or may be increased according to the ink discharge amount. On the other hand, when no image is recorded on the back surface of the paper 12 (S24: No), the standby process (S25) is skipped.

  The rigidity of the paper 12 is further reduced by absorbing ink on both sides. Therefore, as described above, it is desirable that the discharge process (S19) for the paper 12 on which the images are recorded on both sides is executed after waiting for the landed ink to dry. Note that the processes of steps S24 and S25 may be executed before the discharge process of step S16.

  Furthermore, the control unit 130 determines the rotation amount of the transport motor 102 (that is, the rotation amount of the transport roller 60 and the discharge roller 62) in the discharge process (S19) for the paper 12 on which images are recorded on both the front surface and the back surface. It may be increased compared to the discharge process (S19) for the paper 12 on which the image is recorded only. This control can also be applied to the discharge process in step S16. Note that the amount of rotation of the transport motor 102 in the discharge process (S19) varies depending on the position on the paper 12 where the image is recorded last. That is, the comparison of the rotation amounts is based on the premise that the image recording is completed at the same position on the paper 12 on which images are recorded on both sides and the paper 12 on which images are recorded only on one side.

  The frictional force between the ink adhering surface of the paper 12 and the paper discharge tray 21 is larger than the frictional force between the surface not adhering to the ink and the paper discharge tray 21. That is, the paper 12 with ink attached to both the front and back surfaces does not move smoothly on the paper discharge tray 21 due to this frictional force, and the rear end of the paper 12 may not pass through the discharge roller portion 55. . However, according to the above configuration, the rear end of the low-rigidity paper 12 can surely pass through the discharge roller portion 55, so that the low-rigidity paper 12 can be reliably discharged.

DESCRIPTION OF SYMBOLS 10 ... MFP 12A ... preceding paper 12B ... succeeding paper 20 ... paper feed tray 21 ... paper discharge tray 21A ... support surface 25 ... paper feed roller 60 ... transport Roller 62 ... discharge roller 102 ... transport motor 104 ... drive transmission mechanism 130 ... control unit

Claims (6)

A paper feed unit for feeding the paper supported by the paper feed tray;
A transport roller for transporting the fed paper in the transport direction;
A recording unit that is disposed downstream of the transport roller in the transport direction, and that records an image on paper;
A discharge roller that is disposed on the downstream side of the recording unit and conveys the paper in the conveyance direction;
A motor,
When the motor rotates in one direction, a driving mechanism that rotates the transport roller and the discharge roller in a direction in which the paper is transported along the transport direction;
A paper discharge tray that supports the paper transported in the transport direction by the discharge rollers;
Control is provided with a control unit, the,
The control unit
In the paper feed unit, the paper which is supported on the paper feed tray by the sheet feeding, the sheet feeding process the sheet that has paper feed Ru to reach the conveying roller,
The motor is rotated in the one direction, to the conveying roller and the discharge roller, the sheet is conveyed by a predetermined linefeed width in the conveying direction, and in the recording unit, the conveyed sheet by a predetermined linefeed width Intermittent recording processing for recording images;
The paper on which an image is recorded on the discharge roller by the intermittent recording process by continuously rotating the motor in the one direction until at least the upstream end of the sheet in the transport direction passes through the discharge roller. A discharge process for transporting in the transport direction;
A rigidity determination process for determining the rigidity of the paper,
When it is determined in the rigidity determination process that the sheet rigidity is equal to or greater than a threshold value, the intermittent recording process for the preceding sheet is performed, the discharge process for the preceding sheet is not performed, and the upstream of the preceding sheet is performed. The paper feeding process for the succeeding paper next to the preceding paper is performed in a state where the end on the side is located upstream of the discharge roller, and the intermittent recording process for the succeeding paper is performed after the paper feeding process. And
When it is determined in the rigidity determination process that the sheet rigidity is less than the threshold value, the intermittent recording process is performed on the preceding sheet and the image recording is completed, and then the discharging process on the preceding sheet is performed. An image recording apparatus that executes the paper feeding process and the intermittent recording process for the succeeding paper after execution . The image recording apparatus according to claim 1, wherein the control unit continues the rotation without stopping the motor during the discharge process in the discharge process. 3. The image according to claim 2, wherein the control unit executes the discharge process when it is determined in the rigidity determination process that the rigidity of the sheet is equal to or greater than a threshold, and when it is determined that the subsequent sheet does not exist. Recording device. When the rigidity of the sheet is determined to be greater than or equal to the threshold in the rigidity determination process, and when the upstream end of the preceding sheet is positioned on the downstream side of the transport roller, the control unit The image recording apparatus according to claim 1, wherein a sheet feeding process is executed. The control unit
When it is determined in the rigidity determination process that the sheet rigidity is equal to or greater than a threshold value, and the upstream recording end of the preceding sheet after the intermittent recording process is performed and the image recording is completed is more than the transport roller. If it is located on the upstream side, an additional conveyance process for rotating the motor in the one direction so as to position the upstream end of the preceding sheet on the downstream side with respect to the conveyance roller,
The image recording apparatus according to claim 1, wherein the sheet feeding process is performed after the additional conveyance process. The image recording apparatus according to claim 1, wherein a support surface of the paper discharge tray on which the discharged paper is supported is located immediately below a contact position of the discharge roller with the paper.

Images