JP2011057352A - Image recording device having double feed determination function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording device capable of eliminating the waste of recording media since, when an image on a front surface is recorded in one of a plurality of double fed recording media, an image can be recorded on the rear surface of the one recording medium. <P>SOLUTION: When recording paper sheets are double fed, a printer part 14 coveys one sheet of recording paper sheet, on the front surface of which a first image is recorded, among the plurality of recording paper sheets to a re-conveying part 28 for recording a second image on the rear surface thereof, and discharges the other recording paper sheets to a paper discharging part 23 utilizing the value of the displaced length of the plurality of double-fed recording paper sheets and the switching of a switch-back roller 76, which rotates in the forward/reverse directions, from the forward rotation to the reverse rotation. The second image is recorded on the rear surface of the recording paper sheet conveyed to the re-conveying part 28. Therefore, images are recorded on both surfaces of the recording paper sheet conveyed to the re-conveying part 28, respectively. On the other hand, the recording paper sheet discharged to the discharging part 23 is recycled since the recording paper sheet is left vacant. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image recording apparatus having a recording medium double feed determination function, and more particularly to an image recording apparatus capable of recording images on both sides of a double fed recording medium. is there.

  The facsimile apparatus described in Patent Document 1 includes a paper feed cassette on which recording media are stacked, a paper feed roller that feeds the loaded recording media, and a transfer unit that records an image on the fed recording medium. A recording unit, a size detection plate and a pre-registration sensor for detecting whether or not the recording medium is double fed are provided. The size detection plate detects the size of the paper feed cassette, and the size of the paper feed cassette is determined according to the size of the recording medium to be loaded. That is, the size detection plate can detect the value of the length in the conveyance direction of one recording medium. Further, the pre-registration sensor is disposed upstream of the recording unit in the recording medium conveyance direction. The control unit of the facsimile apparatus detects a length value from the front end to the rear end of one or a plurality of recording media conveyed by a signal from the pre-registration sensor. Therefore, the control unit of the facsimile apparatus compares the length value detected by the size detection plate with the length value detected by the signal of the pre-registration sensor to determine whether or not the recording medium has been double fed. Judging.

  When the recording medium is double-fed, the control unit of the facsimile apparatus further uses the position of the image appearing on the recording medium (the value of the margin length on the leading end side of the conveyed recording medium) to double-feed. The recording position of the image on the plurality of recording media is determined. When the image is stored on one of the multiple fed recording media, the control unit performs a reception end process. However, if an image is recorded across multiple recording media that have been fed multiple times, the control unit performs control to record the image again on the newly fed recording medium, and then performs a reception end process. To do.

Japanese Patent Laid-Open No. 7-41207

  In the facsimile apparatus described in Patent Literature 1, no consideration is given to recording images on both sides of a recording medium. Even if this facsimile apparatus has a configuration for recording images on both sides of the recording medium, if the recording medium is double-fed, the image is recorded on the back side of the recording medium that has been double-fed. The In other words, even if the image on the front side is recorded on one of the multiple fed recording media, the image on the back side is recorded on the other side of the other fed back side. The For this reason, even if the image on the front side fits on one recording medium, there is a problem that all of the multiple recording media that are multi-fed are wasted.

  The present invention has been made in order to solve the above-mentioned problems, and its purpose is that when an image on the front surface is recorded on one of a plurality of multi-fed recording media. Another object of the present invention is to provide an image recording apparatus capable of recording an image on the back surface of the single recording medium and eliminating the waste of the recording medium.

  In an image recording apparatus that records a first image on a front surface and a second image on a back surface of a recording medium, a recording unit that records the image, a feeding mechanism that includes a feeding roller that feeds the recording medium, and recording Conveying the recording medium from the feeding mechanism toward the recording unit in a predetermined conveying direction so that the surface of the medium opposite to the surface where the feeding roller contacts is opposed to the recording unit A recording medium is sandwiched between a mechanism, a first roller that rotates in the forward and reverse directions, and the first roller, and the recording medium is moved in cooperation with the first roller by the forward rotation of the first roller. A second roller that conveys the recording medium in a direction opposite to the predetermined conveying direction in cooperation with the first roller by reversing the first roller, and forward and reverse rotation of the first roller. A switchback mechanism having a drive unit for driving in the direction; A reversing mechanism for reversing the front and back of the recording medium conveyed by the reverse rotation of one roller and conveying the recording medium toward the recording unit; a double feeding determining unit for determining that the recording medium has been double-fed from the feeding mechanism; An image for determining whether or not the first image is recorded on the most subsequent recording medium among a plurality of the multi-recorded recording media when the multi-feed determining unit determines that the multi-feed is performed. When the rear end of the determination medium and the recording medium that is most rearward in the predetermined transport direction among the plurality of multi-recorded recording media is positioned at a position between the first roller and the second roller A position determination unit that determines whether or not a rear end of the other recording medium is positioned on the downstream side of the first predetermined value or more with respect to the sandwiching position; and among the plurality of multi-fed recording media, the predetermined recording medium The leading edge of the recording medium that precedes most in the transport direction is After reaching the holding position, the trailing edge of the most subsequent recording medium reaches the clamping position, and the trailing edges of the other recording media are transported more downstream than the clamping position by the first predetermined value or more. A predetermined amount determining unit that determines the amount of forward rotation of the first roller until the predetermined amount is determined as a predetermined amount, and the multi-feed determining unit determines that the multi-feed is performed, and the image determining unit determines that the first image is the most When it is determined that the recording medium is recorded in a subsequent recording medium and the rear end of the recording medium that is most subsequent is positioned at the clamping position, the rear end of the other recording medium is When it is determined that the first roller is positioned on the downstream side by a first predetermined value or more than the sandwiching position, the first roller reaches the sandwiching position after the leading edge of the most preceding recording medium reaches the sandwiching position. Control the drive of the drive unit so that it rotates backward after a predetermined amount of forward rotation And a control unit that controls the operation of the recording unit so as to record the second image on the recording medium conveyed by being reversed upside down by the reversing mechanism.

  According to this configuration, when the recording medium is double-fed and the first image is stored in the recording medium that is most downstream, the one recording medium is transported to the reversing mechanism and the back surface thereof. A second image is recorded in On the other hand, other recording media are not conveyed to the reversing mechanism. Therefore, one or a plurality of recording media that are not conveyed to the reversing mechanism remain blank without the second image being recorded. Therefore, even if the recording medium is double-fed, if the first image is recorded on one recording medium, the second image is recorded on the back side of the one recording medium. Can be eliminated.

  The image recording apparatus according to claim 2, wherein the control unit determines that the double feed determination unit has been double-fed, and the image determination unit fits in a recording medium on which the first image is most succeeding. When it is determined that recording is not performed, or when the rear end of the recording medium that is most succeeded by the position determination unit is positioned at the holding position, the rear end of the other recording medium is set to a first predetermined value from the holding position. When it is determined that it is not positioned on the downstream side, all the rear ends of the multiple fed recording media in the predetermined transport direction are transported more downstream than the nipping position by the first predetermined value or more. Until then, the drive of the drive unit is controlled so that the first roller rotates normally.

  According to this configuration, when the recording medium is double-fed and the first image is not recorded by being recorded in the most subsequent recording medium, or the trailing edge of the most subsequent recording medium is the clamping position. When the rear end of the other recording medium is not positioned more than the first predetermined value or more downstream from the sandwiching position when the recording medium is positioned, the plurality of multi-recorded recording media are not conveyed to the reversing mechanism. Therefore, the second image is not recorded on these recording media. Here, when the first image fits in the recording medium that follows most and is not recorded, a part of the first image is recorded on each of the multiple fed recording media. In addition, when the trailing edge of the most subsequent recording medium is positioned at the clamping position, the trailing edge of the other recording medium is not positioned downstream of the clamping position by a first predetermined value or more. Only the recording medium to be performed cannot be conveyed to the reversing mechanism. Therefore, in these cases, even if one or a plurality of recording media are conveyed to the reversing mechanism and the second image is recorded by the image recording unit, the first image and the second image only on both sides of the one recording medium. Images are not recorded. Accordingly, when the first image is recorded across a plurality of recording media, or when only the recording medium that follows most cannot be transported to the reversing mechanism, these recording media are not transported to the reversing mechanism. Thus, useless recording operations can be prevented.

  The image recording apparatus according to claim 3, wherein the recording medium is conveyed in the predetermined conveyance direction by forward rotation of the first roller, and a rear end is conveyed more downstream than the clamping position by the first predetermined value or more. Is further provided with a discharge part.

  According to this configuration, the recording medium whose rear end is conveyed to the downstream side by the first predetermined value or more with respect to the clamping position due to the forward rotation of the first roller is discharged to the discharge unit. On the other hand, the recording medium whose rear end has reached the clamping position due to normal rotation of the first roller is conveyed to the reversing mechanism due to reverse rotation of the first roller. Accordingly, the recording medium is discharged to the discharge portion or transferred to the reversing mechanism depending on whether the rear end of the recording medium is transported to the downstream side by the first predetermined value or more from the sandwiching position or to the sandwiching position. Can be switched.

  5. The image recording apparatus according to claim 4, wherein the predetermined amount determination unit is configured to detect a recording medium that follows most after a leading edge of a recording medium that precedes the plurality of multi-fed sheets reaches the clamping position. The trailing edge reaches the clamping position, and the trailing edge of the other recording medium is conveyed further downstream than the clamping position by a length corresponding to the radius of the first roller or the second roller. The normal rotation amount of the first roller up to is determined as the predetermined amount.

  According to this configuration, when the first roller rotates forward by a predetermined amount, the rearmost recording medium is sandwiched between the first roller and the second roller at the rear end. On the other hand, the rear end of the other recording medium is conveyed downstream from the clamping position by a length corresponding to the radius of the first roller or the second roller. At this time, the other recording medium is more reliably separated from the most subsequent recording medium by its own weight. Therefore, other recording media are not conveyed to the reversing mechanism even if the first roller is reversed. Therefore, by transporting the rear end of the other recording medium to the downstream side by a length corresponding to the radius of the first roller or the second roller from the sandwiching position, the most out of the plurality of recording media that are multi-fed. Only the subsequent recording medium can be more reliably transported to the reversing mechanism.

  The image recording apparatus according to claim 5, a recording medium length storage unit that stores a length value of one recording medium, and a leading end of the conveyed recording medium or recording sheets in the predetermined conveying direction A leading end length calculating unit that calculates a length value from the leading end to the trailing end, and a deviation length based on a value obtained by subtracting a value stored in the recording medium length storage unit from a value calculated by the leading end length calculating unit. A deviation length calculation unit that calculates a value, and the image determination unit calculates a margin length value until the first image appears from a leading edge of a conveyed recording medium. If it is larger than the value of the deviation length, it is determined that the first image is recorded on the recording medium that is the most succeeding.

  According to this configuration, whether the first image is recorded on the most subsequent recording medium among the plurality of recording media on which the first image is double-fed depending on whether the margin length value is larger than the deviation length value. It is determined whether or not. Therefore, it is possible to reliably determine that the first image is stored in the recording medium that is the most subsequent one among the plurality of recording media that have been multi-fed.

  The image recording apparatus according to claim 6, wherein the double feed determination unit determines that the recording medium has been double fed when the value of the deviation length is larger than a second predetermined value.

  According to this configuration, it can be easily determined that double feeding has been performed.

  The image recording apparatus according to claim 7, wherein the position determination unit is configured to perform the predetermined conveyance among a plurality of multi-feed recording media when the deviation length value is larger than the first predetermined amount. When the rear end of the recording medium that is the most rearward in the direction is located at the clamping position, it is determined that the rear ends of the other recording media are located downstream of the clamping position by the first predetermined value or more.

  According to this configuration, it is possible to easily determine whether only the most subsequent recording medium among the plurality of recording media that have been multi-fed is conveyed to the reversing mechanism.

  The image recording apparatus according to claim 8, wherein the predetermined amount determination unit determines the predetermined amount based on a value calculated by the leading and trailing end length calculation unit.

  According to this configuration, the predetermined amount can be easily determined.

  According to the image recording apparatus of the present invention, when an image on the front side is recorded on one of a plurality of recording media that have been multi-fed, the image is recorded on the back side of the single recording medium. Since the image is recorded, the waste of the recording medium can be eliminated.

1 is an external perspective view of a multifunction machine 10 according to an embodiment of the present invention. 1 is a schematic sectional view of a printer unit 14 according to an embodiment of the present invention. Explanatory drawing which shows the state which the switching flapper 74 of the switching part 26 concerning embodiment of this invention is located in a discharge position in order to guide a recording paper to the paper discharge part 23 In the state where the switching flapper 74 of the switching unit 26 according to the embodiment of the present invention is located at the discharge position, the trailing edge of the recording paper P2 that follows and the trailing edge of the preceding recording paper P1, and the switchback roller pair Explanatory drawing which shows the positional relationship with 56 clamping positions. Explanatory drawing which shows the state which the switching flapper 74 of the switching part 26 based on embodiment of this invention is located in a re-conveying position in order to guide a recording paper to the re-conveying part 28. 1 is a block diagram showing a control system of a multifunction machine 10 according to an embodiment of the present invention. The flowchart which shows the double-sided recording operation performed by the control part 96 which concerns on embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate.

Embodiment

  FIG. 1 is an external perspective view of a multifunction machine 10 according to an embodiment of the present invention. In the following description, the vertical direction 1 is defined with reference to the state of FIG. 1 in which the multifunction machine 10 is installed, and the front-rear direction 2 is defined with the side on which the operation panel 12 is provided as the front side. The horizontal direction 3 is defined when the multifunction machine 10 is viewed from the front side.

  The multifunction machine 10 is a substantially rectangular parallelepiped that is longer in the left-right direction and the front-rear direction than in the up-down direction. The multifunction machine 10 includes a printer unit 14 at the bottom, a scanner unit 16 at the top, and an operation panel 12 at the front top. Details of the printer unit 14 will be described below. The details of the scanner unit 16 and the operation panel 12 are not described here.

[Configuration of Printer Unit 14]
As shown in FIG. 2, the printer unit 14 includes an image recording unit 18, a paper feed unit 20, a paper discharge unit 23, a main transport unit 24, a switching unit 26, a re-transport unit 28, and a detection unit 29. And have. The main transport unit 24 transports the recording paper from the paper supply unit 20 to the switching unit 26 via the image recording unit 18. The switching unit 26 switches the conveyance direction of the recording paper in order to record an image on the back surface of the recording paper. The re-conveying unit 28 conveys the recording paper whose conveying direction has been switched to the main conveying unit 24 again. Each configuration will be described below.

[Image Recording Unit 18]
The image recording unit 18 is disposed at the upper part of the printer unit 14 and records an image on a recording sheet. The image recording unit 18 includes a recording head 30, a carriage 32 that supports the recording head 30, and a platen 60 that supports the recording paper so as to face the recording head 30.

  The recording head 30 can eject ink droplets, and ink is supplied from an ink cartridge (not shown).

  The carriage 32 on which the recording head 30 is supported can reciprocate in the left-right direction. The carriage 32 is connected to a CR motor 34 (see FIG. 6) that is a drive source. The carriage 32 reciprocates in the left-right direction when the rotation of the CR motor 34 is transmitted through a first transmission mechanism (not shown) including a plurality of gears. As the carriage 32 reciprocates, the recording head 30 ejects ink droplets. As a result, an image is recorded on the recording paper facing the recording head 30.

  The platen 60 is a member that is disposed below the recording head 30 and extends across the front and rear and the left and right. The platen 60 supports the recording paper being recorded on the upper surface of the platen 60 substantially horizontally.

[Paper Feeder 20]
The paper feed unit 20 includes a paper feed cassette 22 on which recording paper can be stacked, and a paper feed mechanism 36. The recording paper fed by the paper feeding mechanism 36 is guided by a main transport unit 24 described later, and an image is recorded by the image recording unit 18.

  The paper feed cassette 22 is a box-like member that is disposed at the bottom of the printer unit 14 and has an open upper surface. Various sizes of recording paper can be loaded on the paper feed cassette 22. The paper feed cassette 22 can be inserted and removed in the front-rear direction from an opening 37 (see FIG. 1) formed on the front surface of the printer unit 14.

  The paper feed mechanism 36 is disposed above the paper feed cassette 22. The basic configuration of the paper feed mechanism 36 is known, and the configuration is disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-247542. Hereinafter, the configuration of the paper feed mechanism 36 will be briefly described. The paper feed mechanism 36 includes a paper feed roller 38 that feeds the stacked recording paper and a support arm 40 that supports the paper feed roller 38.

  The paper feed roller 38 is rotatably provided, and is provided so as to be able to contact and separate from the recording paper loaded in the paper feed cassette 22. The paper feed roller 38 is connected to an LF motor 42 (see FIG. 6) that is a drive source. The sheet feed roller 38 is rotated by the rotation of the LF motor 42 transmitted through a second transmission mechanism (not shown) including a plurality of gears. The paper feed roller 38 rotates forward by the rotation of the LF 42 motor in the forward direction, and transports the recording paper toward the main transport unit 24. The paper feed roller 38 is configured not to rotate when the LF motor 42 rotates in the reverse direction.

  The support arm 40 is a rod-shaped member that supports the paper feed roller 38 on one end side and is supported by the shaft 41 on the other end side. The support arm 40 is provided so as to be rotatable about a shaft 41. The shaft 41 is fixed to a frame (not shown) of the printer unit 14.

  Further, the support arm 40 is urged so that the paper feed roller 38 moves downward by its own weight or a spring (not shown). As a result, the paper feed roller 38 contacts the upper surface of the recording paper loaded in the paper feed cassette 22. When the paper feed cassette 22 is inserted and removed, the support arm 40 rotates about the shaft 41 so that the paper feed roller 38 moves upward. As a result, the paper feed roller 38 moves upward and retreats from the insertion / extraction area of the paper feed cassette 22.

[Paper Discharge Unit 23]
As shown in FIG. 1, the paper discharge unit 23 is disposed above the front side of the paper feed cassette 22, and supports the recorded recording paper that has been discharged on the upper surface of the paper discharge unit 23. The paper discharge unit 23 is configured integrally with the paper feed cassette 22 and can be inserted into and removed from the printer unit 14 together with the paper feed cassette 22.

[Main transport section 24]
As shown in FIG. 2, the main transport unit 24 is arranged from the vicinity of the upper end of the paper feed cassette 22 through the image recording unit 18 to the rear of the switching unit 26 described later. The main transport unit 24 transports the recording paper so that the recording paper reaches the switching unit 26 after passing through the image recording unit 18. The main transport unit 24 includes a curved guide 58 and a discharge guide 62 that guide the recording paper, and a transport roller pair 52 and a discharge roller pair 54 that transport the recording paper. The recording paper conveyed by the main conveyance unit 24 is conveyed on the main conveyance path 50.

  The curved guide 58 is a generally arcuate member that extends from the downstream side of the paper supply unit 20 to the upstream side of the image recording unit 18 and has an inner side of the printer unit 14 as a center. Here, the upstream side and the downstream side refer to the upstream side and the downstream side in the transport direction 55 when the recording paper is transported on the main transport path 50 in the transport direction 55 indicated by the two-dot chain arrow in FIG. It is. Hereinafter, they are simply referred to as “upstream side” and “downstream side”. The recording paper conveyed by the paper supply roller 38 is conveyed so as to make a U-turn from below to above along the inner surface of the curved guide 58. For this reason, the recording paper is conveyed such that the lower surface opposite to the upper surface with which the paper feed roller 38 is in contact is opposed to the recording head 30. When the recording paper is transported by the paper feed roller 38 toward the main transport unit 24, another recording paper is put on one recording paper transported by the paper feeding roller 38, and two recording papers In some cases, so-called double feeding occurs. When the recording paper is double-fed, the recording paper abutted by the paper feed roller 38 is often transported prior to the recording paper being carried. Therefore, after the two recording sheets are fed in a state where they are shifted and overlapped, when the paper is turned upside down by the curved guide 58, the subsequent recording sheet P2 is placed on the preceding recording sheet P1 so as to partially overlap. State (see FIG. 3).

  The discharge guide 62 is a member that extends from the downstream side of the image recording unit 18 to the upstream side of the switching unit 26 described later. The discharge guide 62 supports the recorded recording paper substantially horizontally on the upper surface of the discharge guide 62.

  The conveyance roller pair 52 is disposed in front of the curved guide 58 and behind the image recording unit 18. The conveyance roller pair 52 includes a conveyance roller 64 that is driven, and a first pinch roller 66 that is pressed against the conveyance roller 64 and rotates following the conveyance roller 64. The transport roller pair 52 transports the recording paper transported along the curved guide 58 toward the image recording unit 18. The first pinch roller 66 is disposed below the conveying roller 64.

  The discharge roller pair 54 is disposed in front of the image recording unit 18 and behind the discharge guide 62. The discharge roller pair 54 includes a driven discharge roller 68 and a second pinch roller 70 that is in pressure contact with the discharge roller 68 and rotates following the discharge roller 68. The discharge roller pair 54 conveys the recording paper on which the image is recorded by the image recording unit 18 toward the discharge guide 62. The second pinch roller 70 is disposed above the discharge roller 68.

  The conveyance roller 64 and the discharge roller 68 are connected to a PF motor 72 (see FIG. 6) that is a drive source. The conveyance roller 64 and the discharge roller 68 are rotated by the rotation of the PF motor 72 transmitted through a third transmission mechanism (not shown) including a plurality of gears. The conveyance roller 64 and the discharge roller 68 are configured to rotate only in the direction in which the recording paper is conveyed further downstream from the arrangement position of each roller.

[Switching unit 26]
The switching unit 26 is disposed in front of the discharge guide 62. The switching unit 26 switches the transport direction to whether the recording paper transported from the main transport unit 24 is discharged to the paper discharge unit 23 or guided to a re-transport unit 28 described later. The switching unit 26 includes a switchback roller pair 56 that rotates in the forward and reverse directions to switch the recording paper conveyance direction, and a switching flapper 74 that switches the recording paper guide direction.

  The switchback roller pair 56 is disposed downstream of the discharge guide 62 and upstream of the paper discharge unit 23. The switchback roller pair 56 includes a switchback roller 76 that is driven, and a third pinch roller 78 that is in pressure contact with the switchback roller 76 and rotates following the switchback roller 76. The switchback roller 76 can rotate in forward and reverse directions. The recording paper conveyed on the conveyance guide 62 is conveyed toward the paper discharge unit 23 by the normal rotation of the switchback roller 76. On the other hand, the recording paper is conveyed in the reverse direction by the reverse rotation of the switchback roller 76. The third pinch roller 78 is disposed above the switchback roller 76.

  The switchback roller 76 is connected to the LF motor 42 that is a drive source. The switchback roller 76 is rotated by the rotation of the LF motor 42 transmitted through a fourth transmission mechanism (not shown) including a plurality of gears. The LF motor 42 can be driven in forward and reverse directions, and the switchback roller 76 rotates in the forward and reverse directions as the LF motor 42 rotates.

  The switching flapper 74 is disposed behind the third pinch roller 78 and switches the recording paper guide direction. The switching flapper 74 includes a first auxiliary roller 80, a flapper portion 81, and a second auxiliary roller 82. The first auxiliary roller 80 is rotatably supported by the frame of the printer unit 14. The flapper portion 81 extends rearward from the first auxiliary roller 80 and is provided so as to be rotatable about the first auxiliary roller 80. The second auxiliary roller 82 is disposed at the extended end of the flapper portion 81 and moves up and down as the flapper portion 81 rotates.

  The switching flapper 74 has a “discharge position” shown in FIG. 3 and a “re-transfer position” shown in FIG. 5 by its rotation.

  As shown in FIG. 3, at the discharge position of the switching flapper 74, the second auxiliary roller 82 is positioned at substantially the same height as the first auxiliary roller 80. At this time, the switching flapper 74 guides the recording paper conveyed on the discharge guide 62 to be conveyed toward the paper discharge unit 23.

  As shown in FIG. 5, at the re-conveying position of the switching flapper 74, the second auxiliary roller 82 is positioned obliquely below and behind the first auxiliary roller 78. At this time, the switching flapper 74 guides the recording paper conveyed by the reverse rotation of the switchback roller pair 56 to be conveyed toward the re-conveying unit 28.

  The switching flapper 74 is connected to the LF motor 42 that is a drive source. The switching flapper 74 rotates when the rotation of the LF motor 42 is transmitted via a fifth transmission mechanism (not shown) including a plurality of gears.

  The switching flapper 74 is rotated to the discharge position by the rotation of the LF motor 42 in the forward direction, and is rotated to the re-transport position by the rotation in the reverse direction. When the switching flapper 74 is located at the discharge position, the recording paper conveyed on the discharge guide 62 reaches the switchback roller pair 56 via the lower side of the switching flapper 74. At this time, since the LF motor 42 is rotating in the forward direction, the recording paper is further conveyed downstream by the forward rotation of the switchback roller 76.

  Thereafter, when the switchback roller 76 is reversely rotated, the switching flapper 74 is rotated to the re-conveying position in synchronization with the reverse rotation. When the switchback roller 76 starts reverse rotation, the trailing edge of the recording paper in the conveyance direction 55 is sandwiched by the switchback roller pair 56. Therefore, when the switchback roller 76 rotates in the reverse direction and the switching flapper 74 rotates to the reconveying position, the recording paper sandwiched by the switchback roller pair 56 is guided to the reconveying unit 28 described later by the switching flapper 74.

[Reconveying unit 28]
As shown in FIG. 2, the re-conveying unit 28 passes from the obliquely lower rear side of the switchback roller pair 56 to the front of the curved guide 58 constituting the main conveying unit 24 through the platen 60 and the paper feeding unit 20. It is arranged across. The re-conveying unit 28 conveys the recording paper conveyed from the switching unit 26 toward the curved guide 58. The re-conveying unit 28 includes a re-conveying guide 84 that guides the recording paper, and a re-conveying roller pair 86 that conveys the recording paper.

  The re-conveying guide 84 is a member that extends from obliquely below the switchback roller pair 56 to the front of the curved guide 58. The re-transport guide 84 supports the recording paper transported from the switching unit 26 on the upper surface of the re-transport guide 84. The recording paper conveyed on the re-conveying guide 84 is guided by the curved guide 58 and conveyed toward the image recording unit 18 so as to make a U-turn again from below to above.

  The re-conveying roller pair 86 is disposed near the center of the re-conveying guide 84 in the front-rear direction. The re-conveying roller pair 86 includes a re-conveying roller 88 that is driven, and a fourth pinch roller 90 that is pressed against the re-conveying roller 88 and rotates following the re-conveying roller 88. The re-conveying roller 88 conveys the recording paper conveyed on the re-conveying guide 84 toward the curved guide 58. The fourth pinch roller 90 is disposed above the re-transport roller 88.

  The re-conveying roller 88 is connected to a PF motor 72 (see FIG. 6) that is a driving source. The re-conveying roller 88 is rotated by the rotation of the PF motor 72 transmitted through a sixth transmission mechanism (not shown) including a plurality of gears. The re-conveying roller 88 is configured to rotate only in the direction of conveying the recording paper further downstream.

[Detection unit 29]
The detection unit 29 includes a registration sensor 51 that detects the presence or absence of recording paper, and a sheet sensor 53. The registration sensor 51 is disposed on the upstream side of the image recording unit 18, the sheet sensor 53 is disposed on the downstream side of the image recording unit 18, and both sensors detect the presence or absence of recording paper in the main conveyance path 50. The registration sensor 51 and the sheet sensor 53 each include a detector (not shown) and an optical sensor (not shown). The detector is arranged so as to cross the main transport path 50 and is configured to be able to protrude or retract from the main transport path 50. The optical sensor is turned on or off by the protrusion or withdrawal of the detector. Accordingly, the position of the leading or trailing edge of the recording paper in the main transport path 50 is detected by changing the recording paper to a state where the detector protrudes or retracts. Here, the leading edge and the trailing edge of the recording paper are the leading edge and the trailing edge of the conveyed recording paper.

[Configuration of Control System of Embodiment]
Next, a control system of the multifunction machine 10 shown in FIG. 6 will be described. The control system controls the overall operation of the multifunction machine 10 including the scanner unit 16, but only control of the operation of the printer unit 14 will be described here.

  The control system determines a predetermined amount for forward rotation of the switchback roller 76, a first storage unit 92 for storing each value to be described later, a calculation unit 94 for performing each calculation to be described later based on a detection result of the detection unit 29. A quantitative determination unit, and an image recording unit 18 and a control unit 96 that controls driving of each drive source by outputs of the calculation unit 94 and the predetermined amount determination unit are provided. Each drive source includes a CR motor 34, an LF motor 42, a PF motor 30, and the like. The predetermined amount determination unit includes a sheet sensor 53, a second storage unit 97, which will be described later, and a calculation unit 94.

  The first storage unit 92 stores recording information for recording an image on recording paper. The recording information includes first image data including a first image and a margin length value to be recorded on the front surface of the recording paper, second image data including a second image to be recorded on the back surface, and one sheet of data. Recording paper data including a value of a length in the conveyance direction of the recording paper (hereinafter simply referred to as “recording paper length”). The recording sheet length is input from the operation panel 12 of the multifunction machine 10 or an external input device such as a PC.

  The calculation unit 94 calculates the length of the leading and trailing edges, which is the length from the leading edge to the trailing edge of one or two sheets of recording paper being conveyed, and the length of the misalignment between the two sheets of recording paper that have been double fed. A value (hereinafter simply abbreviated as “deviation length”) is calculated. In addition, the calculation unit 94 determines whether the deviation length is larger or smaller than each value described later. The calculation unit 94 outputs each calculated value and each comparison result to the control unit 96.

  The front / rear end length is calculated based on the detection result of the registration sensor 51. The calculation unit 94 calculates the leading and trailing edge length, which is the value of the length from the leading edge to the trailing edge, from the leading edge and trailing edge positions of the recording paper detected by the registration sensor 51. That is, the front / rear end length is a value of the length from the front end to the rear end of one or two recording sheets to be transported regardless of whether or not they are double-fed.

  The misalignment length is calculated based on the leading and trailing end lengths and the recording sheet length stored in the first storage unit 92. The calculation unit 94 calculates a value obtained by subtracting the recording paper length and the set value “α” from the leading and trailing edge lengths as the deviation length. In this embodiment, “α” is set to “2 mm” in consideration of the conveyance error of the recording paper and the detection error of the registration sensor 51. The predetermined value “α” is a value stored in the second storage unit 97.

  Further, the arithmetic unit 94 determines whether or not the deviation length is larger than “0”. When the misalignment length is greater than “0”, the control unit 96 determines that the two recording media are fed in a state where they are shifted in the transport direction 55 and overlapped, that is, they are double fed.

  The calculation unit 94 has a deviation length from the length of the margin included in the first image data from the leading edge of the conveyed recording paper (hereinafter simply referred to as “leading margin length”). Judge whether it is large or not. As a result, it can be determined whether or not the first image is stored on one of the two sheets of recording paper that have been double fed. Note that this determination is necessary only when the recording paper is double-fed, and is therefore performed only when it is determined that the misalignment length is greater than “0”.

  Here, when the misalignment length is smaller than the leading edge margin length, the first image is recorded on one of the two sheets of double-fed recording paper. On the other hand, when the misalignment length is larger than the leading edge margin length, the first image is recorded across the two sheets of double-fed recording paper.

  The calculation unit 94 determines whether or not the deviation length is greater than a value R (see FIG. 4) corresponding to the radius of the switchback roller 76 (hereinafter simply referred to as “roller radius length”). As a result, it can be determined whether or not only the recording paper P2 that follows the two of the two recording papers that have been multi-fed can be reliably conveyed to the re-conveying unit 28. Note that this determination is necessary only when the recording paper is double-fed and the first image is recorded on a single sheet. Therefore, the determination is performed only when it is determined that the shift length is smaller than the leading margin length.

  The case where the misalignment length is larger than the roller radius length R (see FIG. 4) is a case where only the following recording sheet P2 out of the two sheets of recording paper that have been multi-fed can be reliably conveyed to the reconveying unit 28. At this time, the preceding recording sheet P1 out of the two recording sheets that have been multi-fed is separated from the following recording sheet P2 and discharged to the sheet discharge section 23 (see FIG. 5). On the other hand, when the deviation length is smaller than the roller radius length R, it is a case where it is not certain that only the recording paper P2 that follows the two of the double-fed recording papers is conveyed to the re-conveying unit 28.

  Of the two sheets of double-fed recording paper, the separation of transporting the subsequent recording paper P2 to the re-conveying unit 28 and discharging the preceding recording paper P1 to the paper discharging unit 23 is performed by a switchback roller. This is performed by switching from forward rotation of 76 to reverse rotation. Details of the separation of the two fed recording sheets will be described later.

  The predetermined amount determination unit includes a second storage unit 97 and a calculation unit 94. The predetermined amount determination unit uses the predetermined value “α” stored in the second storage unit 97 and the leading and trailing end length calculated by the calculation unit 94 to set the value calculated by the calculation unit 94 to the correct value by the switchback roller 76. It is determined as a predetermined amount to roll. The predetermined amount of forward rotation of the switchback roller 76 means that the leading edge of one sheet of recording paper being conveyed or the leading edge of the preceding recording sheet P1 among the two sheets of recording paper being fed is nipped by the switchback roller pair 56. After reaching the position, until the trailing edge of one sheet of conveyed recording paper or the trailing edge of recording paper P2 of two sheets fed double is sandwiched between the switchback roller pair 56 This is the forward rotation amount of the switchback roller 76 that conveys the recording paper. The predetermined amount corresponds to an amount of the recording paper that is transported by the length of the front and rear ends. Therefore, the predetermined amount is determined based on a value obtained by subtracting the set value “α” from the front and rear end lengths in consideration of the conveyance error and the length of the recording paper necessary to be held between the switchback roller pair 56. The At this time, the control unit 96 determines whether or not the leading edge of the conveyed recording paper has reached the holding position of the switchback roller pair 56 based on the detection result of the sheet sensor 53.

  When the recording paper is double-fed when the switchback roller 76 is rotated forward by the predetermined amount, as shown in FIG. 4, the recording paper P2 that follows the two of the double-fed recording papers is shown. The rear end is located upstream from the clamping position of the switchback roller pair 56 and downstream from the discharge guide 62. The trailing edge of the preceding recording paper P1 is from the clamping position of the switchback roller pair 56. Since the roller is conveyed further downstream than the length of the roller radius, it is discharged to the paper discharge unit 23 as shown in FIG. When the trailing edge of the preceding recording paper P1 is transported more downstream than the clamping position of the switchback roller pair 56 by the length of the roller radius, the recording paper P1 is separated from the recording paper P2 that follows by its own weight, The paper is discharged to the paper discharge unit 23. On the other hand, the subsequent recording paper P2 is conveyed in the reverse direction when the switchback roller 76 is reversed, and is guided to the re-conveying unit 28.

[Double-sided recording operation]
Next, a double-sided recording operation executed by the control unit 96 of the multifunction machine 10 will be described with reference to FIG. Each step shown in FIG. 7 is a process executed by the control unit 96. A control program for executing each process of the flowchart shown in FIG. 7 is stored in the internal fixed memory of the control unit 96.

  When a recording operation execution instruction is input from the operation panel 12 of the multifunction machine 10 or an external input device such as a PC, the control unit 96 determines whether or not the input instruction is a double-sided recording operation (S1). When the input instruction is a single-sided recording operation (S1: NO), the control unit 96 executes a normal single-sided recording operation (S2). A detailed description of the single-sided recording operation is omitted.

  On the other hand, when the input instruction is a double-sided recording operation (S1: YES), the control unit 96 checks the recording paper length stored in the first storage unit 92 (S3).

  The controller 96 drives the LF motor 42 so that the paper feed roller 38 rotates (S4). The paper feed roller 38 rotates in contact with the upper surface of the recording paper loaded on the paper feed cassette 22. By this rotation, the recording paper is fed from the paper feed cassette 22 and is conveyed along the curved guide 58 so as to make a U-turn from below to above.

  The controller 96 checks whether the registration sensor 51 has detected the leading edge of the recording paper (S5). When the registrar 51 has not detected the leading edge of the recording paper (S5: NO), the control unit 96 executes the process of step S4 so that the recording paper is further conveyed.

  When the registrar 51 detects the leading edge of the recording paper (S5: YES), the controller 96 drives the PF motor 30 so that the transport roller 64 and the discharge roller 68 are rotated (S6). The leading edge of the recording paper that has passed through the registration sensor 51 reaches the conveyance roller pair 52, and the recording paper is conveyed onto the platen 60 by the conveyance roller pair 52.

  Based on the first image data stored in the first storage unit 92, the control unit 96 records the first image on the front surface of the recording paper conveyed to the platen 60. Is controlled (S7). In the present embodiment, the front surface of the recording paper on which the first image is recorded is the surface opposite to the upper surface of the recording paper with which the paper feed roller 38 is in contact. The leading edge of the recording paper that has passed under the image recording unit 18 is conveyed onto the discharge guide 62 by the discharge roller pair 54. The recording medium conveyed on the discharge guide 62 is detected by the sheet sensor 53.

  The controller 96 checks whether the registration sensor 51 has detected the trailing edge of the recording paper (S8). If the registration sensor 51 has not detected the trailing edge of the recording sheet (S8: NO), the control unit 96 executes the process of step S6 so that the recording sheet is further conveyed. On the other hand, when the registration sensor 51 detects the trailing edge of the recording paper (S8: NO), the control unit 96 executes the process of step S9. Note that when the registration sensor 51 detects the trailing edge of the recording paper, the image recording unit 18 is recording the first image on the recording paper or after the first image is recorded on the recording paper.

  The control unit 96 controls the calculation unit 94 so as to calculate the misalignment length after the trailing edge of the conveyed recording paper passes through the registration sensor 51 (S9).

  The control unit 96 controls the calculation unit 94 so as to calculate the leading edge margin length (S10).

  The control unit 96 controls the calculation unit 94 so as to calculate the predetermined amount (S11).

  The control unit 96 confirms the comparison result between the deviation length in the calculation unit 94 and the value “0” (S12).

  When the arithmetic unit 94 determines that the deviation length is smaller than or equal to “0” (S12: NO), the control unit 96 executes the process of step S14.

  On the other hand, when the arithmetic unit 94 determines that the deviation length is greater than “0” (S12: YES), the control unit 96 executes the process of step S13. If it is determined YES in step S12, the control unit 96 determines that two sheets of recording paper have been fed.

  The control unit 96 checks the comparison result between the deviation length in the calculation unit 94, the leading edge margin length, and the roller radius length R (S13).

  When the calculation unit 94 determines that the misalignment length is greater than or equal to the leading edge margin length, or smaller than or equal to the roller radius length R (S13: NO), the control unit 96 causes the double-feed to be performed. After the recording paper is discharged to the paper discharge unit 23 (S20), the LF motor 42 is driven so that the paper supply roller 38 rotates (S4), and the recording paper is fed again. If NO is determined in step S13, the first image is recorded across the two fed sheets of recording paper, or only one recording sheet on which the first image is stored is recorded. This is a case where it is not certain that the sheet is conveyed to the re-conveying unit 28. Accordingly, it is possible to prevent a wasteful recording operation by discharging the two recording papers that have been double fed and starting over from the paper supply. When the arithmetic unit 94 determines that the misalignment length is larger or smaller than the leading edge margin length, if the first image is being recorded on the recording paper by the image recording unit 18, control is performed. The unit 96 stops the operation of the image recording unit 18 and discharges the recording paper. This can prevent useless recording operations.

  On the other hand, when the calculation unit 94 determines that the deviation length is smaller than the leading edge margin length and larger than the roller radius length R (S13: YES), the control unit 96 executes the process of step S14. If YES is determined in step S13, the first image is recorded and recorded on the subsequent recording paper P2 out of the two sheets of the double-fed recording paper, and only the subsequent recording paper P2 is surely received. This is a case where it can be transported to the re-transport unit 28. In this case, if the second image is recorded on the back surface of the recording paper P2, the first image and the second image can be recorded only on both surfaces of the single recording paper.

  The control unit 96 drives the LF motor 42 so that the switchback roller 76 rotates forward by a predetermined amount (S14). As a result, the two fed sheets of recording paper are separated. When the switchback roller 76 rotates forward by a predetermined amount, the trailing edge of the recording paper P2 that follows the two of the double-fed recording papers is located between the switchback roller pair 56. The rear end of the paper P1 is positioned on the downstream side of the roller radius length R or more from the holding position of the switchback roller pair 56 (see FIG. 4). At this time, since the preceding recording sheet P1 is not sandwiched between the switchback roller pair 56, it is separated from the subsequent sheet by its own weight and discharged to the sheet discharge section 23 (see FIG. 5). As a result, the preceding recording paper P1 is discharged to the paper discharge unit 23 as a blank sheet, so that the waste of the recording sheet can be eliminated by reuse.

  The control unit 96 drives the LF motor 42 in the reverse direction so that the switchback roller 76 reversely rotates (S15). As a result, the recording paper whose rear end is sandwiched between the switchback roller pair 56 is conveyed in the reverse direction.

  Note that the switching flapper 74 is rotated to the re-transport position (see FIG. 5) by driving the LF motor 42 in the reverse direction in step S15. When the switchback roller 76 starts reverse rotation, the trailing edge of the recording paper in the conveyance direction 55 is sandwiched by the switchback roller pair 56. Therefore, when the switchback roller 76 reverses and the switching flapper 74 rotates to the re-conveying position, the recording paper sandwiched by the switchback roller pair 56 is guided to the switching flapper 74 and directed to the re-conveying unit 28 described later. Are transported.

  The control unit 96 drives the PF motor 30 so that the re-conveying roller 88 rotates (S16). Accordingly, the recording paper conveyed on the re-conveyance guide 84 is conveyed toward the curved guide 58. The recording paper conveyed to the curved guide 58 is conveyed so as to make a U-turn from below to above, and conveyed so that the back surface opposite to the front surface on which the first image is recorded faces the recording head 30. .

  The controller 96 checks whether the registration sensor 51 has detected the leading edge of the recording paper (S17). When the registration sensor 51 has not detected the leading edge of the recording paper (S17: NO), the control unit 96 executes the process of step S16 so that the recording paper is further conveyed. On the other hand, when the registration sensor 51 detects the leading edge of the recording paper (S17: YES), the control unit 96 executes the process of step S18.

  Based on the second image data stored in the first storage unit 92, the control unit 96 operates the image recording unit 18 so that the second image is recorded on the back surface of the recording paper conveyed on the platen 60. Is controlled (S18).

  The control unit 96 drives the PF motor 30 and the LF motor 42 so that the recording paper on which the second image is recorded is discharged to the paper discharge unit 23 by the discharge roller pair 54 and the switchback roller pair 56 ( S19).

  According to the MFP 10 according to the embodiment of the present invention, when an image on the front surface is recorded and recorded on one of a plurality of recording media that are multi-fed, that one sheet is recorded. Since the image is recorded on the back surface of the recording medium, it is possible to eliminate the waste of the recording medium.

  Note that the combination of the control unit 96 and the process of step S12 in the present embodiment is an example of the double feed determination unit of the present invention. The combination of the control unit 96 and the process of step S13 is an example of the image determination unit and the position determination unit of the present invention. A combination of the second storage unit 97 and the calculation unit 94 is an example of the predetermined amount determination unit of the present invention. Further, the calculation unit 94 serves as both the front and rear end length calculation unit and the deviation length calculation unit of the present invention.

[Modification]
The multifunction machine 10 only needs to include the printer unit 14. For example, a multifunction machine corresponding to the image recording apparatus of the present invention may not include a scanner unit.

  The printer unit 14 is an inkjet printer having an image recording unit 18 that records an image with ink, but may be any printer that can record an image. For example, the printer unit may be a laser printer having an image recording unit that records an image with toner.

  The recording head 30 of the image recording apparatus 18 is arranged above the conveyance path of the recording paper. However, the present invention is not limited to this, and the recording head 30 may be arranged below the conveyance path.

  The paper feeding unit 20 feeds the recording paper by the paper feeding roller 38 supported by the support arm 40, but may be configured so that the recording paper can be fed. For example, the recording paper is fed by a paper feeding roller fixed to the frame of the printer unit and a paper feeding cassette 22 configured to lift up the recording paper loaded so that the recording paper contacts the paper feeding roller. It may be a paper configuration.

  The paper feed roller 38 is in contact with the upper surface of the stacked recording paper, but may be in contact with the lower surface of the recording paper. In this embodiment, the case where two sheets of recording paper are double-fed is described as an example where the recording paper is double-fed by the paper feed roller 38. However, three or more recording sheets are double-fed. It may be the case.

  The support arm 40 is rotated by its own weight or a spring and insertion / extraction of the paper feed cassette 22, but may be connected to a driving source such as a motor and rotated by transmitting a driving force of the driving source.

  The main transport unit 24 may further include a guide member for guiding the recording paper in addition to the curved guide 58 and the discharge guide 62. The main transport unit 24 guides the recording paper so as to make a U-turn from the lower side to the upper side by the curved guide 58, but the image is recorded on the surface opposite to the surface of the recording paper that the paper feed roller contacts. Any structure may be used as long as it is conveyed.

  The switching unit 26 includes the switchback roller pair 56 and the switching flapper 74. However, the switching unit 26 switches the direction in which the recording paper is conveyed to the direction in which the recording paper is guided to the paper discharge unit or the direction in which the recording paper is guided to the re-conveying unit. If it is. For example, the switching unit may not have the switching flapper 74. The switching unit may have a switching flapper 74 on the downstream side of the switchback roller pair 56 in the transport direction 55.

  The switchback roller pair 56 has a third pinch roller 78 that rotates following the switchback roller 76 to which the driving force is transmitted, but has a third pinch roller 78 below the switchback roller 76. You may do it.

  The paper discharge unit 23 is disposed immediately before the switchback roller pair 56, but may be disposed anywhere as long as the recorded recording paper can be discharged. For example, a guide member for guiding the recording paper to the paper discharge unit may be further provided between the switchback roller pair 56 and the paper discharge unit 23. Further, an intermediate tray that temporarily supports recording paper may be further provided between the switchback roller pair 56 and the paper discharge unit 23.

  The re-conveying unit 28 is arranged over the front side of the curved guide 58 from the diagonally lower rear side of the switchback roller pair 56, but the reverse side of the recording paper on which the image is recorded on the front surface is reversed, and again, Any configuration that can be conveyed to the image recording unit 18 is acceptable. For example, a guide member may be provided that guides the recording paper conveyed by the reverse rotation of the switchback roller 76 so that the front and back of the recording paper are reversed after passing between the recording head 30 and the platen 60.

  The detection unit 29 includes the registration sensor 51 and the sheet sensor 53, but may include only one of the sensors. Further, another sensor may be further provided. The registration sensor 51 and the sheet sensor 53 can detect the presence or absence of recording paper by detecting the thickness of the recording paper or a non-contact sensor such as an ultrasonic sensor, as long as the position of the leading or trailing edge of the recording paper can be detected. It may be a sensor to detect.

  The recording sheet length is a value input from the operation panel 12 or an external input device such as a PC. However, when a plurality of recording sheets are continuously conveyed and an image is recorded, the recording medium conveyed immediately before The front and rear end lengths may be used.

  The front and rear end lengths are calculated based on the detection results of the registration sensor 51, but may be calculated based on the detection results of the sheet sensor 53 as long as they can be used for calculation of the deviation length and comparison with each value. In addition, when the detection unit 29 further includes other sensors, the front and rear end lengths may be calculated based on the detection result of any sensor.

  The set value “α” used for calculating the deviation length and determining the predetermined amount is set to “2 mm”, but is not limited thereto. The set value “α” is a value that is set in consideration of the conveyance error of the recording paper and the detection error of the sensor. Therefore, the setting value “α” is a value that can reliably detect double feeding, and one of a plurality of multi-feed recording papers. “0” if it is a value that can reliably determine whether or not the first image fits on a sheet and is recorded, or a value that can convey only one of a plurality of multi-fed recording sheets to the re-conveyance unit. Any value including can be used.

  The second storage unit 97 stores one set value “α”, but stores the set value used for calculating the deviation length and the set value used for determining the predetermined amount as different arbitrary values. You may do it. Moreover, although the 1st memory | storage part 92 and the 2nd memory | storage part 97 are provided separately, you may provide in one memory.

  The leading edge margin length is defined as the margin length from the leading edge of the recording paper to be conveyed among the margin lengths included in the first image data, but is not limited thereto. The leading edge margin length only needs to be able to determine whether or not the first image is recorded on one of a plurality of sheets of recording paper that have been multi-fed. For example, a sensor for detecting the position of the first image recorded on the recording paper may be further provided, and a margin length value calculated based on the detection result of the sensor may be used.

  The roller radius length R is defined as a value corresponding to the radius of the switchback roller 76, but may be a radius length of a roller disposed below the switchback roller pair 56. If the third pinch roller is disposed below the switchback roller, the roller radius length R is defined as the radius length of the third pinch roller.

  Further, the arithmetic unit 94 uses the roller radius length R for comparison with the deviation length, but any value can be used as long as the two recording sheets can be reliably separated by switching from the forward rotation to the reverse rotation of the switchback roller 76. Instead of the roller radius length R, an arbitrary value may be used.

  The predetermined amount determining unit determines the predetermined amount based on the leading and trailing end lengths and the set value “α”, but may be determined using an arbitrary value set in advance.

  Although the control unit performs a normal single-sided recording operation in step S2, in the normal single-sided recording operation, the control unit 96 performs at least step S3, step S4, step S5, step S6, and step S7. Step S19 is executed. In the normal single-sided recording operation, the control unit 96 calculates a misalignment length in step S9, which will be described later. If the misalignment length is larger than “0” in step S12, the control unit 96 controls to discharge the recording paper. May be. Further, in a normal single-sided recording operation, the control unit 96 calculates the leading edge margin length in step S10 to be described later, and controls to discharge the recording paper when the misalignment length is larger than the leading edge margin length in step S13. May be.

  The control unit 96 confirms the recording paper length in step S3, but is not limited to step S3, and may be confirmed in a step before the deviation length is calculated by the calculation unit 94. The control unit 96 calculates the misalignment length in step S9. However, the present invention is not limited to step S9, and the control unit 96 detects the misalignment length in the arithmetic unit 94 after the registration sensor 51 detects the trailing edge of the recording paper. It is only necessary to calculate in the step before confirming the comparison result with “0”. Further, the control unit 96 calculates the leading edge margin length in step S10. However, the control unit 96 is not limited to step S10, and rather than the control unit 96 confirming the comparison result between the deviation length and the leading edge margin length in the calculation unit 94. What is necessary is just to calculate in the previous step. The control unit 96 calculates the predetermined amount in step S11. However, the control unit 96 is not limited to step S11, and rather than the control unit 96 drives the LF motor 42 so that the switchback roller 76 rotates forward by a predetermined amount. What is necessary is just to calculate in the previous step.

  In step S12, the control unit 96 determines NO when the deviation length is equal to “0”, but may determine YES. Further, the controller 96 determines NO in step S13 when the deviation length is equal to the leading edge margin length, when the deviation length is equal to the roller radius length, or when the deviation length is equal to the leading edge margin length and the roller radius amount. However, it may be determined as YES.

  Further, in step S12 and step S13, the control unit 96 determines whether or not double feeding is performed based on a comparison result between a deviation length, which is a value obtained by subtracting the recording paper length from the leading and trailing edge lengths, and “0”. Whether or not the first image is recorded on one sheet of recording paper is determined based on the comparison result between the length and the leading edge margin length, but the determination is not limited to this. For example, the control unit 96 may compare the value obtained by subtracting the leading edge margin length from the leading and trailing edge length with the recording paper length. In this case, when the value obtained by subtracting the leading margin length from the leading and trailing edge length is larger than the recording paper length, the control unit 96 double feeds the recording paper, and the first image has two sheets. It is determined that the recording is performed across the recording paper. On the other hand, when the value obtained by subtracting the leading margin length from the leading and trailing edge lengths is smaller than the recording sheet length, the control unit 96 does not feed the recording sheets or the first image fits on one recording sheet. It is determined that it will be recorded.

10. Multifunction machine (image recording device)
14: Printer unit 18: Image recording unit (recording unit)
20: Paper feed unit (paper feed mechanism)
23 ... Paper discharge unit (discharge unit)
24 ... Main transport section (part of transport mechanism and reversing mechanism)
26 ... switching part (switchback mechanism)
28 ... Re-conveying part (part of reversing mechanism)
30 ... Recording head 32 ... Carriage 34 ... CR motor 38 ... Paper feed roller (feed roller)
40 ... support arm 42 ... LF motor (drive unit)
50 ... main transport path 51 ... registration sensor 53 ... sheet sensor 56 ... pair of switchback rollers 72 ... PF motor 74 ... switching flapper 76 ... switchback roller (first roller)
78 ... Third pinch roller (second roller)
83: Re-conveying path 92: First storage unit (recording medium length storage unit)
94: Calculation unit 96: Control unit (control unit)

Claims (8)

In an image recording apparatus for recording a first image on the front surface of a recording medium and a second image on the back surface,
A recording unit for recording images;
A feeding mechanism having a feeding roller for feeding the recording medium;
The recording medium is conveyed from the feeding mechanism toward the recording unit in a predetermined conveying direction so that the surface opposite to the surface on which the feeding roller contacts is opposed to the recording unit. A transport mechanism;
The recording medium is sandwiched between a first roller that rotates in the forward and reverse directions and the first roller, and the recording medium is cooperated with the first roller by the forward rotation of the first roller in the predetermined conveying direction. And a second roller for conveying the recording medium in a direction opposite to the predetermined conveying direction in cooperation with the first roller by the reverse rotation of the first roller, and driving the first roller in the forward / reverse rotating direction. A switchback mechanism having a drive unit to
A reversing mechanism for reversing the front and back of the recording medium conveyed by the reverse rotation of the first roller and conveying the recording medium toward the recording unit;
A double feed determining unit for determining that the recording medium is double fed from the feeding mechanism;
An image for determining whether or not the first image is recorded on the most subsequent recording medium among a plurality of the multi-recorded recording media when the multi-feed determining unit determines that the multi-feed is performed. A determination unit;
When the trailing edge of the recording medium that is the most rearward in the predetermined transport direction is located at the nipping position between the first roller and the second roller, the other recording medium A position determination unit that determines whether or not a rear end of the medium is positioned on the downstream side of the clamping position by a first predetermined value or more;
Among the plurality of double-fed recording media, the leading edge of the recording medium that is the most preceding in the predetermined transport direction reaches the clamping position, and then the trailing edge of the recording medium that is the most subsequent reaches the clamping position. And a predetermined amount determining unit that determines the normal rotation amount of the first roller until the rear end of the other recording medium is conveyed to the downstream side of the first predetermined value or more from the clamping position as a predetermined amount; ,
The multi-feed determining unit determines that the multi-feed has been performed, the image determining unit determines that the first image is recorded on the recording medium that is the most subsequent, and the position determining unit is the latest. When it is determined that when the rear end of the recording medium to be moved is located at the sandwiching position, the rear end of the other recording medium is located downstream of the sandwiching position by a first predetermined value or more, the first roller The drive of the drive unit is controlled so as to reverse after the predetermined amount of normal rotation after the leading edge of the recording medium that is the most preceding of the plurality of multi-feeds reaches the clamping position, and the reverse mechanism An image recording apparatus comprising: a control unit that controls an operation of the recording unit so as to record the second image on a recording medium conveyed in an inverted manner.   The control unit determines that the multifeed determination unit determines that the multifeed has been performed, and the image determination unit determines that the first image is not recorded on the most subsequent recording medium, or the position When the determination unit determines that the trailing edge of the most subsequent recording medium is positioned at the clamping position, the trailing edge of the other recording medium is not positioned downstream of the clamping position by a first predetermined value or more. In the predetermined transport direction, the first roller rotates in the forward direction until all rear ends of the plurality of multi-feed recording media are transported to the downstream side by the first predetermined value or more from the sandwiching position. The image recording apparatus according to claim 1, wherein the driving of the driving unit is controlled as described above.   The apparatus further comprises a discharge unit that discharges the recording medium that is transported in the predetermined transport direction by forward rotation of the first roller and whose rear end is transported more than the first predetermined value downstream from the clamping position. 3. The image recording apparatus according to 1 or 2.   The predetermined amount determining unit is configured such that the leading edge of the most preceding recording medium among the plurality of multi-fed sheets reaches the clamping position, and then the trailing edge of the recording medium that follows most reaches the clamping position; and The normal rotation amount of the first roller until the trailing edge of the other recording medium is conveyed downstream from the clamping position by a length corresponding to the radius of the first roller or the second roller. The image recording apparatus according to claim 1, wherein the image recording apparatus is determined as the predetermined amount. A recording medium length storage unit for storing a length value of one recording medium;
A leading and trailing edge length calculating unit that calculates a length value from the leading edge to the trailing edge in the predetermined conveying direction of one or a plurality of conveyed recording media;
A deviation length calculation unit that calculates a deviation length value based on a value obtained by subtracting a value stored in the recording medium length storage unit from a value calculated by the leading and trailing end length calculation unit;
The image determination unit is configured such that when a margin length value from the leading end of the recording medium to be conveyed to the appearance of the first image is larger than a deviation length value calculated by the deviation length calculation unit, The image recording apparatus according to any one of claims 1 to 4, wherein the image recording apparatus determines that the image is recorded on a recording medium that is most downstream.   The image recording apparatus according to claim 5, wherein the double feed determination unit determines that the recording medium is double fed when the value of the deviation length is larger than a second predetermined value.   The position determination unit, when the displacement length value is larger than the first predetermined amount, out of the plurality of multi-fed recording media, the trailing edge of the recording medium that is the most trailing in the predetermined transport direction 7. The image recording apparatus according to claim 5, wherein when the image recording medium is positioned at the clamping position, it is determined that the rear end of the other recording medium is positioned more downstream than the clamping position by the first predetermined value or more.   The image recording apparatus according to claim 5, wherein the predetermined amount determining unit determines the predetermined amount based on a value calculated by the leading and trailing end length calculating unit.

Images