JP2014101228A - Image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recording device capable of preventing deterioration of jam mainly in a second path.SOLUTION: A multifunction machine 10 comprises: a first path comprising a carrying path 31; and a second path 33 reversed from the carrying path 31. The multifunction machine further comprises a first guide 68 for opening and closing the second path 33. The first guide 68 is suspended from a drive shaft 70, and turns by its own weight. The first guide 68 opens and closes by insertion and extraction of a paper feeding cassette 15. The multifunction machine comprises a detection arm 50 for detecting recording paper passing through the second path 33. The detection arm 50 is provided in a position apart by distance D1 from the drive shaft 70. Distance D2 to a reference face (a virtual plane 76) on which the paper feeding cassette 15 is placed from the drive shaft 70 is longer than the distance D1. When the detection arm 50 does not detect the recording paper, a control part stops carriage of the recording paper when carriage distance of the recording paper in the second path 33 reaches the distance D2.

Description

  The present invention relates to an image recording apparatus for recording an image on a sheet, and more particularly to an image recording apparatus capable of recording an image on both a first surface (front surface) and a second surface (back surface) of a sheet. Is.

  There is known an image recording apparatus capable of recording images on both front and back surfaces of a sheet (typically recording paper) (see, for example, Patent Document 1). In the image recording apparatus disclosed in Patent Document 1, a recording sheet pulled out from a paper feed tray is transported along a transport path, and an image is recorded on the surface. The recording sheet having the image recorded on the front side is sent to the reverse path and turned upside down, and then returned to the transport path to record the image on the back side. In the image recording apparatus disclosed in this document, a part of the reversing path can be opened and closed, and the reversing path is opened and closed in conjunction with the attachment and detachment of the paper feed tray.

JP 2008-213981 A

  By the way, an image recording apparatus capable of double-sided recording is required to stop the conveyance of the recording sheet before the recording sheet is damaged even if a jam occurs on the recording sheet having an image recorded on the surface. Is done. Because if the conveyance of the recording paper is stopped before it is damaged, there is no need to re-record the image on the new recording paper (recording on the front surface), and only the image recording on the back surface of the recording paper is performed again. This is because it only has to be done.

  The image recording apparatus does not include a sensor for detecting the attachment / detachment state of the paper feed tray or a sensor for detecting the open / close state of the reversing path. Therefore, even if the paper feed tray is detached after the recording paper is pulled out from the paper feed tray and before the recording paper is sent to the reverse route, it cannot be determined that the reverse route is open. is there. Therefore, if the recording paper is continuously conveyed even though the reversing path is opened, the jammed state may be further deteriorated and the recording paper may be damaged. Of course, such a problem can be solved by adding a sensor for detecting the attachment / detachment state of the paper feed tray or a sensor for detecting the open / close state of the reversing path, but this increases the manufacturing cost of the image recording apparatus.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image recording apparatus that does not deteriorate a jam in an inversion path with a simple and inexpensive structure.

(1) An image recording apparatus according to the present invention includes a sheet cassette that holds a sheet fed in a first direction along a first path starting from a first end, and the first path from the sheet cassette. An image is recorded on the first surface of the sheet sent to the sheet, and the sheet is returned from the first pass to the first pass again through the second pass starting from the second end opposite to the first end. A recording unit for recording an image on the second surface of the recording medium, and a downstream of the first pass to the second pass, the first direction downstream in the transport direction, and transports the sheet by normal rotation or reverse rotation. A first roller that is conveyed in the first direction or a second direction in the conveying direction, and a first arm that can be projected and retracted in the second path, and the first arm is in contact with the sheet conveyed along the second path. Conveyance detection that detects the sheet by Means, a first guide that extends obliquely downward from the branch port toward the downstream side of the second path and that is provided to be rotatable about a support shaft, and a sheet on which an image is recorded on the first surface When the conveyance detecting means does not detect the sheet even when a distance necessary to reach at least the first arm in the second direction of conveyance along the second path by reversing the conveyance roller, A controller that stops the conveying roller, and the first guide forms a lower wall surface in the vertical direction that defines the second path by mounting the sheet cassette, and the conveying direction is determined by the conveying roller. A first posture for guiding the sheet conveyed in the second direction along the second path, and the sheet cassette is rotated to rotate vertically downward about the support shaft when the sheet cassette is detached. So that the seat is separated from the second path and the posture of the second path is changed to a second position that opens upstream from the first arm of the second path so that contact between the seat and the first arm is avoided. It is configured.

  According to this configuration, when the sheet cassette holding the sheet is mounted, the sheet can be fed to the first path, and at the same time, the first guide is displaced to the first posture and the second path is partitioned. The When the conveying roller rotates forward, the sheet is conveyed in the first direction along the first path with the first end as the head, and an image is recorded on the first surface by the recording unit. When an image is also recorded on the second surface of the sheet, the conveyance roller reverses and the sheet is conveyed in the second direction of conveyance starting from the second end. When the sheet enters the second path, the sheet comes into contact with the first arm, and the first arm is pushed by the sheet and sunk from the second path. Thereby, the presence of the sheet is detected by the conveyance detection unit, and it can be determined that the sheet is normally conveyed along the second path. The sheet sent to the second path is conveyed again in the first direction in the conveying direction along the first path with the second end as the head, and an image is recorded on the second surface by the recording unit.

  When the sheet cassette is removed, the first guide changes to the second posture. As a result, the first guide that has formed the wall surface on the lower side in the vertical direction that divides the second path rotates downward in the vertical direction, and the second path is opened. Thus, when the first guide changes its posture, the user can easily perform so-called jam processing when a jam occurs in the second pass.

  By the way, the sheet cassette may be removed while the sheet is being conveyed, either intentionally or unintentionally by the user. In that case, the sheet sent to the second path leaves the second path downward in the vertical direction and moves to the outside of the second path, so that a jam occurs. If the sheet continues to be fed in the second direction in the conveying direction in this state, the jammed state may deteriorate and the sheet may be damaged. However, when the sheet moves to the outside of the second pass, the sheet moves to the outside of the second pass while avoiding contact with the first arm. Regardless, a state occurs in which the conveyance detection unit does not detect the presence of the sheet. The control unit stops the conveyance roller when the conveyance detection unit does not detect the presence of the sheet even if a predetermined time elapses after the conveyance roller is reversed. This prevents the jammed state of the sheet from getting worse.

  (2) The first arm is a gap formed between the front end of the first arm and the wall surface when the first guide is changed to the second posture, and the first arm is vertically downward. It is preferable that the sheet is allowed to pass and is arranged on the downstream side of the second path from the position of the gap different from the second path.

  In this configuration, when the first guide changes to the second posture, the sheet always leaves the second path. Therefore, even if the sheet cassette is removed and a jam occurs, the deterioration of the jam is surely prevented.

(3) The apparatus may further include a contact portion that is disposed vertically below the second path and contacts the bottom surface of the sheet cassette when the sheet cassette is mounted. The sheet cassette is mounted between the second path and the contact portion, and the first arm starts to reverse the conveying roller when the first guide is in the first posture. The distance from when the sheet is conveyed by the reverse rotation of the conveying roller until the sheet reaches the first arm along the second path is D1, and the first guide is in the second posture. The distance from when the reverse rotation of the conveyance roller is started until the sheet conveyed by the reverse rotation of the conveyance roller leaves the second path and reaches the virtual plane including the contact portion is defined as D2. In this case, it is preferable that the lens is disposed at a position where the relationship of D1 <D2 is established.

  In this configuration, when the sheet is sent by the distance D2 in the second direction of conveyance by the reverse rotation of the conveyance roller, the sheet is separated from the second path when the conveyance detection unit does not detect the sheet. Can be determined. Therefore, the control unit can stop the conveyance roller based on the rotation number of the conveyance roller, and the rotation control of the conveyance roller is simplified. In addition, since the first arm is disposed at a position where the relationship of D1 <D2 is established, if the first guide is in the second posture, the sheet moved to the outside of the second path is in contact with the second path. The transport roller is stopped before reaching the virtual plane including the portion. That is, the transport roller is stopped in a state where the leading edge of the sheet is in the mounting area of the sheet cassette. Therefore, when the first guide is in the second posture, the seat is prevented from buckling against the contact portion or the like.

  (4) It is preferable that a biasing member that biases the first arm so as to protrude with respect to the second path is further provided.

  If the sheet cassette is removed while the sheet is being conveyed as described above, the sheet sent to the second pass should move to the outside of the second pass. However, for example, the sheet may reach the first arm even though the second path is opened due to the rigidity of the sheet (so-called seat waist). In this case, if the first arm is easily submerged from the second pass, it is detected as normal sheet conveyance even though the second pass is released. Then, the sheet may move to the outside of the second path after being detected by the conveyance detection unit. In this case, if the sheet continues to be fed in the second direction of conveyance, the jammed state of the sheet deteriorates. Resulting in. However, in the present invention, since the first arm is biased so as to protrude with respect to the second path, such erroneous detection is suppressed.

  (5) Provided downstream of the recording unit in the first direction of conveyance, supports the second surface of the sheet on which the image is recorded on the first surface by the recording unit, and moves the sheet in the first direction of conveyance. A second guide having a guide support surface for guiding may be further provided. The conveyance detection means has a second arm that can protrude and retract from the guide support surface with respect to the first path on the downstream side in the first conveyance direction from the recording portion of the first path, and an outer peripheral surface. And a rotation center shaft on which the first arm and the second arm protrude from the outer peripheral surface, and the sheet conveyed along the first path or the second path is the first arm or It is preferable that the sheet conveyed along the first path or the second path is detected by rotating the rotation center axis in contact with the second arm.

  The sheet on which the image is recorded on the first surface is fed in the first direction of conveyance while being supported by the guide support surface of the second guide. When the sheet comes into contact with the second arm, the conveyance detection unit detects that the sheet is conveyed along the first path. Thereby, when the image is recorded on the second surface, the switchback of the sheet, that is, the reverse timing of the transport roller in the transport direction second direction can be accurately controlled.

The first arm and the second arm are operated simultaneously by the rotation of the rotation center axis. Therefore, when a sheet having an image recorded on the first surface is conveyed along the first path, the sheet comes into contact with the second arm, and the conveyance detection unit outputs a detection signal. When the sheet having an image recorded on the first surface is conveyed along the second path in the second direction of conveyance, the sheet comes into contact with the first arm, and the conveyance detection unit outputs a detection signal. . As described above, since it is detected by the single sensor that the sheet is conveyed in both the first pass and the second pass, the structure of the conveyance detection unit is extremely simplified.

(6) The image recording apparatus rotates between a state in which the second pass is partitioned by mounting the sheet cassette and a state in which the second path is opened by removing the sheet cassette. It is preferable to provide a moving third guide.

(7) It is preferable that the third guide is rotatably provided on the downstream side of the second path with respect to the first arm.

  According to the present invention, it is possible to detect the deterioration of the jam state in the second pass with a simple and inexpensive structure, and it is possible to prevent the sheet from being damaged.

FIG. 1 is an external perspective view of a multifunction machine 10 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the multifunction machine 10. FIG. 3 is an enlarged view of a main part in FIG. FIG. 4 is a perspective view of the second guide 44 provided in the multifunction machine 10. FIG. 5 is an enlarged view of a main part in FIG. FIG. 6 is a cross-sectional view of a main part of the multifunction machine 10 with the first guide 68 opened. FIG. 7 is a block diagram illustrating a configuration of the control unit 90 of the multifunction machine 10.

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

[Schematic configuration of MFP 10]

  FIG. 1 is an external perspective view of a multifunction machine 10 according to an embodiment of the present invention. As shown in the figure, the multifunction machine 10 is integrally provided with a printer unit 11 and a scanner unit 12, and has a print function, a scan function, a copy function, and a facsimile function. The printer unit 11 corresponds to the image recording apparatus according to the present invention. The multifunction machine 10 does not necessarily have the scanner unit 12, and the image recording apparatus according to the present invention may be implemented as a single-function printer that does not have a scanner function or a copy function. Therefore, description of the detailed configuration of the scanner unit 12 is omitted.

  A printer unit 11 is provided in the lower part of the multifunction machine 10. An opening 13 is formed on the front side of the printer unit 11. The paper feed cassette 14 and the paper feed cassette 15 are mounted on the printer unit 11 through the opening 13. The paper feed cassettes 14 and 15 can hold a regular rectangular recording paper 16 (corresponding to a “sheet” recited in the claims: see FIG. 3). The recording paper 16 is selectively supplied into the printer unit 11 from the paper feed cassette 14 or the paper feed cassette 15. The recording paper 16 supplied to the printer unit 11 is discharged onto the upper surface 18 of the paper feed cassette 15 after an image is recorded by the recording unit 17 (see FIG. 2). Therefore, the upper surface 18 of the paper feed cassette 15 functions as a paper discharge tray.

An operation panel 19 is provided in the upper front portion of the multifunction machine 10. The operation panel 19 includes a display that displays various types of information and an input key that receives input of information. MFP 1
0 operates based on instruction information input from the operation panel 19 or instruction information transmitted from an external information device through a printer driver, a scanner driver, or the like.

[Printer section]

  As shown in FIG. 2, the paper feed cassette 14 and the paper feed cassette 15 (corresponding to “sheet cassette” described in the claims) are arranged in two upper and lower stages with the paper feed cassette 15 as the upper side. Each of the paper feed cassettes 14 and 15 holds a recording paper 16 on which image recording is performed. By providing two independent paper feed cassettes 14 and 15, recording paper 16 having a different size and paper type can be held.

  The paper feed cassette 14 is formed in a box shape, and a part of the rear upper side (left side in FIG. 2) of the multifunction machine 10 is opened. The recording paper 16 is placed inside the paper feed cassette 14 in a stacked state. The paper feed cassette 14 can accommodate recording papers 16 of various sizes such as A4 size, B5 size, and postcard size, for example, A3 size or smaller. The paper feed cassette 15 is also a box-like shape in which a part on the upper rear side of the multifunction machine 10 is opened, and recording paper 16 of various sizes can be accommodated in the paper feed cassette 15. The upper surface 18 of the paper feed cassette 15 is provided on the front side (the right side in FIG. 2) of the multifunction machine 10.

  A curved conveyance path 21 is formed above the inclined plate 20 of the paper feed cassette 15. When the paper feed cassette 15 is attached to the printer unit 11, the inclined plate 20 is disposed below the conveyance path 21, and the paper feed roller 25, the arm 26, and the shaft 27 are disposed above the paper feed cassette 15. The paper feed roller 25 is rotatably provided on the tip side of the arm 26. The arm 26 is rotatably supported by a shaft 27, and the shaft 27 is supported by a housing 72 of the printer unit 11. The arm 26 is urged to rotate toward the sheet feeding cassette 15 by its own weight or by receiving an elastic force from a spring or the like.

  A curved conveyance path 23 is formed on the upper side of the inclined plate 22 of the paper feed cassette 14. When the paper feed cassette 14 is attached to the printer unit 11, the inclined plate 22 is disposed below the conveyance path 23, and the paper feed roller 28, the arm 29, and the shaft 30 are disposed above the paper feed cassette 14. The paper feed roller 28 is rotatably provided on the tip end side of the arm 29. The arm 29 is rotatably supported by the shaft 30, and the shaft 30 is supported by the casing 72 of the printer unit 11. The arm 29 is urged to rotate toward the sheet feeding cassette 14 by its own weight or by receiving an elastic force from a spring or the like.

[First pass / Second pass]

  FIG. 3 is an enlarged view of a main part in FIG. A conveyance path 31 that is continuous with the conveyance path 23 and the conveyance path 21 is formed inside the printer unit 11. In addition, the conveyance path 23, the conveyance path 21, and the conveyance path 31 correspond to the “first path” recited in the claims. The conveyance path 31 is a path for further conveying the recording paper 16 conveyed along the conveyance path 23 or the conveyance path 21 to the right side in FIG. The conveyance path 31 extends from the position where the conveyance path 23 and the conveyance path 21 merge toward the front side of the multifunction machine 10 and above the upper surface 18 of the sheet feeding cassette 15. The direction from the position where the conveyance path 23 and the conveyance path 21 merge to the front side of the multifunction machine 10 is the “first direction in the conveyance direction”.

A second path 33 is formed by branching from the downstream side of the conveyance path 31 (upstream side of a switchback roller 32 described later). As shown in the drawing, the second path 33 is connected to the upstream side of the first path (upstream side of the transport path 31). As a result, the multifunction device 10 can record the image on both the front and back sides of the recording paper 16 by turning the recording sheet 16 upside down. Specifically, the second path 33 forms a branch port 48 at an upstream position of the switchback roller 32 (corresponding to “carrying roller” recited in the claims), and the branch port 48 and the conveyance path 31. Is connected to the upstream side.

  The recording paper 16 pulled out from the paper feed trays 14 and 15 is transported along the transport path 23 (transport path 21) and the transport path 31 with the first end (for example, the front end) as the head, and is recorded on the first surface by the recording unit 17. An image is recorded (for example, on the surface). When an image is also recorded on the back side, the recording paper 16 is switched back from the transport path 31 to the second path 33 with the second end (rear end) as the head, and returned to the transport path 31 again. As a result, the recording paper 16 is turned upside down, and an image is recorded on the back side by the recording unit 17.

  A registration sensor 34 is disposed on the upstream side of the conveyance path 31. Specifically, a registration sensor 34 is provided on the upstream side in the first conveyance direction of a conveyance roller 35 described later. The registration sensor 30 detects the presence or absence of the recording paper 16 that passes through the conveyance path 31. Whether the leading edge or the trailing edge of the recording paper 16 has reached the position where the registration sensor 30 is provided is determined based on the ON / OFF signal change from the registration sensor 30.

[Platen / Recording section]

  As shown in FIGS. 2 and 3, a platen 36 is provided in the conveyance path 31. The platen 36 supports the recording paper 16 conveyed along the conveyance path 31 from below. The recording unit 17 is disposed above the platen 36. The upper surface of the platen 36 is colored so as to have a reflectance different from that of the recording paper 16. Since the recording paper 16 is usually white, the upper surface of the platen 36 is typically colored black.

  The recording unit 17 includes a carriage 24 disposed on the upper side of the conveyance path 31 and a platen 36 disposed on the lower side. The carriage 24 has an inkjet recording head 80 mounted thereon. The ink jet recording head 80 is disposed opposite to the platen 36, and minute ink is directed toward the platen 36 when the carriage 24 is reciprocated in a direction perpendicular to the first direction of conveyance (direction perpendicular to the paper surface). Drops are selectively ejected. The ejected ink droplets land on the recording paper 16 supported by the platen 36. In this way, a desired image is recorded on the recording paper 16 by alternately conveying the recording paper 16 and reciprocating the carriage 24.

[Feed roller pair]

  A feed roller pair 37 is arranged along the transport path 31 on the upstream side in the first transport direction with respect to the platen 36. The feed roller pair 37 includes a transport roller 35 and a pinch roller 38. The conveyance roller 35 is disposed on the upper side of the conveyance path 31 and rotates by the driving force transmitted from the LF motor 85 (see FIG. 7). The pinch roller 38 is rotatably disposed below the conveyance roller 35 with the conveyance path 31 interposed therebetween, and is urged toward the conveyance roller 35 by a spring. The holding force of the recording paper 16 by the conveying roller 35 and the pinch roller 38 is stronger than the holding force by the switchback roller 35 and the spur 41. Note that the holding force of the recording paper 16 by the conveying roller 35 and the pinch roller 38 is stronger than the holding force by the discharge roller 39 and the spur 40 described later, and the holding force by the discharge roller 39 and the spur 40 is the switchback roller. It is stronger than the clamping force by 35 and the spur 41.

[Discharge roller pair]

A discharge roller pair 42 is provided on the downstream side of the platen 36 in the first conveyance direction. The discharge roller pair 42 includes a discharge roller 39 and a spur 40. The paper discharge roller 39 is rotated by the driving force transmitted from the LF motor 85 (see FIG. 7). The spur 40 is rotatably disposed above the paper discharge roller 39 with the conveyance path 31 interposed therebetween, and is urged by a spring toward the paper discharge roller 39. Since the paper discharge roller 39 and the spur 40 sandwich the recording paper 16 after image recording, the clamping force is set to be weaker than the clamping force of the recording paper 16 by the transport roller 35 and the pinch roller 38.

[Switchback roller pair]

  A switchback roller pair 43 is provided downstream of the discharge roller pair 42 in the first direction of conveyance. The switchback roller pair 43 includes a switchback roller 32 and a spur 41. The switchback roller 32 is rotated by the driving force transmitted from the LF motor 85 (see FIG. 7). The spur 41 is rotatably disposed above the switchback roller 32 with the conveyance path 31 in between, and is urged by a spring toward the switchback roller 32. The switchback roller 32 can rotate forward and backward. As the switchback roller 32 rotates forward, the recording paper 16 is conveyed in the first direction of conveyance and is discharged to the upper surface 18 of the paper feed tray 15. As the switchback roller 32 rotates in the reverse direction, the recording paper 16 is conveyed in the second direction of conveyance opposite to the first direction of conveyance. That is, the recording paper 16 is switched back. The holding force of the switchback roller 32 and the spur 41 may be set to be smaller than the holding force of the feed roller pair 37 and the discharge roller pair 42 as long as it is sufficient to discharge or switch back the recording paper 16. ing.

[Second Guide / Sheet Detection Mechanism]

  A second guide 44 is disposed between the discharge roller pair 42 and the switchback roller pair 43. The second guide 44 extends substantially horizontally along the transport direction. The second guide 44 includes a guide support surface 45, and this guide support surface 45 defines a part of the transport path 31. The recording paper 16 is guided downstream while being supported by the guide support surface 45. The second guide 44 is provided with a recess 46. The recess 46 is a groove opened in the guide support surface 45 and extends in the transport direction. The function of this groove will be described later.

  FIG. 4 is a perspective view of the second guide 44. FIG. 5 is an enlarged view of a main part in FIG. The second guide 44 is provided with a sheet detection mechanism 47 (corresponding to “conveyance detection means” described in claims). The conveyance detection mechanism 47 detects the presence or absence of the recording paper 16 passing through the conveyance path 31 or the second path 33 (see FIG. 3). The sheet detection mechanism 47 includes a rotation center shaft 51, a detection arm 49 (corresponding to “second arm” recited in claims), a detection arm 50 (corresponding to “first arm” recited in claims), The optical sensor 56 (refer FIG. 7: photo interrupter, for example) and the rotation wheel 52 (equivalent to the "biasing means" described in the claim) are provided. When the recording paper 16 is transported along the transport path 31 and transported along the second path 33 (see FIG. 3), the detection arm 49 and the detection arm 50 fall down in the transport direction. The optical sensor 56 detects this and outputs an on / off signal. Thereby, it is determined whether the leading edge or the trailing edge of the recording paper 16 has reached the position where the detection arm 49 or the detection arm 50 is provided.

  As shown in FIG. 4, the rotation center shaft 51 is a rod-shaped member made of resin. The rotation center shaft 51 extends in a direction intersecting with the conveyance direction of the recording paper 16. The rotation center shaft 51 is supported by the guide member 44. As shown in the figure, a pair of support plates 53 project from the inner wall of the guide member 44. The support plate 53 is formed integrally with the guide member 44. Both ends of the rotation center shaft 51 are rotatably supported by the support plate 53.

  A detection arm 49 protrudes from one end side of the rotation center shaft 51. The detection arm 49 protrudes from the outer peripheral surface of the rotation center shaft 51 and extends in the radial direction. Accordingly, the detection arm 49 penetrates the second guide 44 upward and is exposed in a standing state at the center of the guide support surface 45. The detection arm 50 is also provided on the outer peripheral surface of the rotation center shaft 51. The detection arm 50 is disposed so as to substantially face the detection arm 49, and extends in the radial direction of the rotation center shaft 51. Accordingly, the detection arm 50 penetrates the lower surface 54 of the second guide 44 downward and protrudes downward from the center of the lower surface 54. A slit 55 is provided in the guide support surface 45 and the lower surface 54 of the second guide 44. The detection arm 49 and the detection arm 50 are inserted into the slit 55, and the detection arm 49 and the detection arm 50 can fall down along the slit 55 as the rotation center shaft 51 rotates.

  As shown in FIGS. 4 and 5, a notch 57 is provided in the lower portion of the second guide 44. The notch 57 is provided on the lower surface 54 of the second guide 44 and is cut from the downstream edge 62 of the second path 33 to the upstream side of the second path 33. The wall surface that defines the cutout 57 forms the cutout 57 in a rectangular shape. The dimension in the width direction 48 of the notch portion 57 is set to be larger than the dimension in the width direction 48 of the rotation wheel 52, and the rotation wheel 52 can be moved forward and backward with respect to the notch portion 57. When the rotating wheel 52 enters the notch portion 57, it comes into contact with the inner back wall 59 (corresponding to the “contact portion” described in the claims) that defines the notch portion 57. That is, the inner back wall 59 abuts on the turning wheel 52 and restricts the entry of the turning wheel 52.

  The rotation wheel 52 is provided at the other end of the rotation center shaft 51. That is, the rotation wheel 52 is arranged at a position different from the detection arm 49 and the detection arm 50 with respect to the axial direction of the rotation center shaft 51. The rotation wheel 52 may be formed integrally with the rotation center shaft 51 or may be fixed to the rotation center shaft 51 by a known fixing means. In the present embodiment, the rotation wheel 52 is made of a substantially fan-shaped plate member and protrudes in the radial direction of the rotation center shaft 51. Since the rotation wheel 52 protrudes in the radial direction of the rotation center shaft 51, the rotation center shaft 51 receives a moment due to the weight of the rotation wheel 52. The direction of this moment is the direction of the arrow 61 in FIG.

  Therefore, in FIG. 3, the rotation center shaft 51 is always urged to rotate counterclockwise, and the detection arm 49 is always raised from the guide support surface 45 (that is, rotated upstream in the first direction in the transport direction). Further, the detection arm 50 is biased so as to always protrude downward from the lower surface 54 of the guide member 44 (that is, to rotate upstream in the transport direction of the second path 33). However, as shown in FIG. 5, the rotation wheel 52 abuts on the inner back wall 59, so that the rotation center shaft 51 is rotated counterclockwise (in the direction of the arrow 61), but the inner back wall 59. Rotation is regulated by. That is, the detection arm 49 is restricted from falling from the posture shown in FIG. 3 to the upstream side in the first conveyance direction of the conveyance path 31, and the detection arm 50 is conveyed from the posture shown in FIG. 3 in the conveyance direction of the second path 33. It is restricted to fall to the upstream side.

As shown in FIG. 3, when the recording paper 16 is transported along the transport path 31 in the first transport direction, the recording paper 16 moves the detection arm 49 after passing the guide support surface 45 of the second guide 44. The rotation center shaft 51 is rotated by receiving a clockwise moment (in the direction of arrow 60 in FIG. 5) in FIG. Thereby, the rotation wheel 52 is retracted from the notch portion 57 in FIG. 5, and the detection arm 49 is laid down downstream in the first direction of conveyance. Since the detection arm 49 falls down, the recording paper 16 is smoothly fed along the transport path 31. When the recording paper 16 is switched back and conveyed along the second path 33, the detection arm 50 is pressed, and the rotation center axis 51 is rotated clockwise in FIG. 3 (indicated by the arrow 60 in FIG. 5). Direction) and rotate. Thereby, the rotation wheel 52 is retracted from the notch 57 in FIG. 5, and the detection arm 50 is laid down on the downstream side in the transport direction of the second path 33. Since the detection arm 50 is laid down, the recording paper 16 is smoothly fed along the second path 33 and enters the transport path 21 again.

  The optical sensor 56 is disposed inside the second guide 44, and the photo interrupter is fixed to the second guide 44. The photo interrupter is disposed at a position crossed by a rotation wheel 52 that rotates in conjunction with the rotation of the rotation center shaft 51. The optical sensor 56 is configured to be turned on or off when the rotating wheel 52 crosses the photo interrupter.

[flap]

  As shown in FIGS. 2 and 3, a flap 63 is provided between the discharge roller pair 42 and the switchback roller pair 43 along the first path 22. The flap 63 is rotatably supported on the shaft 64. The shaft 64 is arranged on the discharge roller pair 42 side (upstream side in the first conveyance direction) from the branch port 48. The flap 63 includes a frame 65 and a first auxiliary roller 66 and a second auxiliary roller 67 provided on the frame 65. A base end portion of the frame 65 is supported by the shaft 64, and the frame 65 extends along the transport path 31 in the first transport direction. The first auxiliary roller 66 is rotatably disposed at a substantially central portion of the frame 65, and is disposed downstream of the shaft 64 in the first conveyance direction. Further, the second auxiliary roller 67 is rotatably disposed at the distal end portion of the frame 65.

  As shown in FIG. 6, the first auxiliary roller 66 can be fitted into the recess 46 provided in the second guide 44 when the frame 65 rotates around the support shaft 66. That is, the flap 63 rotates clockwise about the shaft 64 in FIG. 3, and the first auxiliary roller 66 can enter the recess 46. The posture of the flap 63 at this time is defined as the approach posture. As shown in FIG. 3, the flap 63 rotates counterclockwise about the shaft 64, and the first auxiliary roller 66 can be retracted from the recess 46. The posture of the flap 63 at this time is defined as the exit posture.

  At all times, the flap 63 is in the approach posture due to its own weight. When the recording paper 16 is transported on the guide support surface 45 along the transport path 31 downstream in the first transport direction, the recording paper 16 and the first auxiliary roller 66 are pushed up. As a result, the flap 63 changes to the retracted posture, and the recording paper 16 is further sent downstream in the first direction of conveyance. As the recording paper 16 is transported, the recording paper 16 is sandwiched between the switchback roller pair 43 and further fed in the first transport direction. When the recording paper 16 passes through the first auxiliary roller 66, the first auxiliary roller 66 is fitted into the recess 46, so that the flap 63 changes to the approaching posture.

  When the flap 63 is in the approach posture, the second auxiliary roller 67 presses the second end side of the recording paper 16 downward, and the second end of the recording paper 16 is corrected in the direction of the second path 33. If double-sided recording is not performed, the switchback roller 32 continues normal rotation and the recording paper 16 is discharged. When image recording is also performed on the back surface of the recording paper 16, the switchback roller is used when the second end of the recording paper 16 reaches the stop position 90 between the first auxiliary roller 66 and the second auxiliary roller 67. The reversal of 32 is started, and the recording paper 16 is reliably sent to the second path 33 with the second end as the head. The stop position 90 is a position upstream of the second auxiliary roller 67 in the first direction of conveyance and in the vicinity of the second auxiliary roller 67.

[First Guide]

A first guide 68 that is rotatable about the drive shaft 70 is provided on the upstream side of the second path 33 in the second conveyance direction. As shown in FIG. 3, the second path 33 extends obliquely downward from the branch port 48. The first guide 68 changes its posture between a first posture and a second posture. When the first guide 68 is in the first posture, the first guide 68 extends obliquely downward along the second path 33 from the drive shaft 70. A bearing portion 69 is provided at the base end of the first guide 68, and the bearing portion 69 is engaged with the switchback roller pair 43. Specifically, the bearing portion 69 is engaged with a drive shaft 70 (corresponding to a “support shaft” recited in the claims) of the switchback roller 32 and is rotatably supported by the drive shaft 70. ing. The first guide 68 is formed in a flat plate shape. Concavities and convexities are formed along the width direction at the center portion in the width direction of the tip 73 of the first guide 68. The first guide 68 extends in a direction perpendicular to the paper surface in FIG. 3 and reliably supports the recording paper 16 conveyed along the second path 33. Further, as shown in the figure, the first guide 68 extends from the position where the switchback roller 32 is disposed to the downstream side of the second path 33, and the upper surface 71 of the first guide 68 has a second path 33. A part of the wall surface (part of the wall surface on the lower side in the vertical direction) is formed. The posture in which the first guide 68 divides the second path 33 and guides the recording paper 16 along the second path 33 in this way is defined as the “first posture”.

  When the first guide 68 is in the second posture, it extends vertically downward from the drive shaft 70. The first guide 68 can be suspended by its own weight. Accordingly, the first guide 68 can release the second path 33 by rotating counterclockwise around the drive shaft 70 in FIG. 3 (see FIG. 6). The posture in which the first guide 68 releases the second path 33 in this way is defined as the “second posture”.

  In the present embodiment, when the first guide 68 is in the first posture, the tip 73 of the first guide 68 extends to a position upstream of the detection arm 50 of the second path 33. For this reason, when the first guide 68 is in the second posture, the upstream side of the detection arm 50 in the vertically lower wall surface of the second path 33 is opened. Specifically, as shown in FIG. 6, a predetermined gap is formed between the tip 73 of the first guide 68 and the wall surface 74 of the second path 33. The predetermined gap is a space different from the second path 33 formed on the lower side in the vertical direction, and the recording paper 16 can leave the second path 33 and pass through the contact with the detection arm 50. It is a gap. The wall surface 74 is formed by a member fixed to the housing 72. Concavities and convexities are formed along the width direction at positions corresponding to the concavities and convexities formed at the tip 73 in the central portion of the wall surface 74 in the width direction so as to alternate with the concavities and convexities formed at the tip 73. In addition, the front end side including the concavo-convex portion of the wall surface 74 is inclined toward the side away from the second path toward the upstream side in the second conveyance direction. Thereby, the sheet conveyed along the second direction of conveyance can be stably conveyed.

  In addition, the 1st guide 68 can open | release the 2nd path | pass 33 largely by rotating counterclockwise further from the 2nd attitude | position shown in FIG. Moreover, the 1st guide 68 comprises a part of wall surface which closes the 2nd path | pass 33 and divides the said 2nd path | pass 33 by rotating clockwise from the hanging state. In the present embodiment, the rotation of the first guide 68 is performed by inserting and removing the paper feed cassette 15. That is, when the paper feed cassette 15 is inserted into the printer unit 11, the upper end 81 of the paper feed cassette 15 presses the lower surface 82 of the first guide 68, and the second path 33 rotates clockwise. Note that the upper end 81 of the paper feed cassette 15 and the lower surface 82 of the first guide 68 are respectively provided on one end side in the width direction. When the paper feed cassette 15 is pulled out from this state, the first guide 68 is rotated by its own weight, and the second path 33 is released. At this time, the tip 73 of the first guide 68 has irregularities alternately formed with the irregularities of the wall surface 74, and is not supported by the wall surface 74, so when the paper feed cassette 15 is pulled out, the first guide 68. Changes its posture to the second posture.

In the present embodiment, the first guide 68 rotates about the support shaft 53 by its own weight, but the first guide 68 may be biased to rotate counterclockwise about the drive shaft 70. Good. The specific structure of the urging means varies, but typically, a torsion coil spring is interposed between the rotating shaft 70 and the first guide 68. In this embodiment, the switchback roller 3
The two drive shafts 70 also serve as a support shaft that supports the first guide 68, but a support shaft that supports the first guide 68 may be provided separately from the drive shaft 70.

  FIG. 6 is a cross-sectional view of a main part of the multifunction machine 10 with the first guide 68 opened. As shown in the drawing, the paper feed cassette 15 is inserted inside the housing 72 and below the second path 33. The paper feed cassette 15 is mounted on a plurality of contact portions 75 (corresponding to “contact portions” recited in the claims) for supporting the bottom surface of the paper feed cassette 15 provided in the housing 72. Is done. The abutting portion 75 supports the paper feeding cassette 15 by abutting against the bottom surface of the paper feeding cassette 15 in a mounted state. A surface along the horizontal plane connecting the plurality of contact portions 75 is defined as a virtual plane 76 (corresponding to a “virtual plane” recited in the claims). The contact portion 75 is configured to contact a part of the bottom surface of the paper feed cassette 15, but may be configured to contact the entire bottom surface of the paper feed cassette 15. Although a plurality of contact portions 75 are provided, only one contact portion 75 may be provided.

  As shown in FIG. 3, when the first guide 68 is in the second posture, the recording paper 16 conveyed by the switchback roller pair 43 after the reverse rotation of the switchback roller 32 is started, the contact portion 75. The distance to reach the virtual plane 76 including is defined as the distance D2. Specifically, when the first guide 68 is in the second posture, the recording paper 16 whose second end is located at the stop position 90 is conveyed by the reverse rotation of the switchback roller 32 and reaches the virtual plane 76. Is the distance. When the first guide 68 is in the second posture, a part of the vertically lower wall surface of the second path 33 is opened, so that the recording paper 16 is conveyed toward the virtual plane 76 by its own weight. Further, as shown in FIG. 6, when the first guide 68 is in the first posture, the recording paper 16 conveyed by the switchback roller pair 43 after the reverse rotation of the switchback roller 32 is started in the second pass. The distance to reach the detection arm 50 along 33 is defined as the distance D1. Specifically, when the first guide 68 is in the first posture, the recording paper 16 whose second end is located at the stop position 90 is conveyed by the reverse rotation of the switchback roller 32, and along the second path 33. This is the distance to reach the detection arm 50. In this embodiment, the position of the detection arm 50, that is, the position of the rotation center axis 51 is determined so that the relationship D1 <D2 is established between the distance D1 and the distance D2.

  The multi-function device 10 according to the present embodiment is configured such that when the first guide 68 is in the first posture, the tip 73 of the first guide 68 is positioned upstream of the detection arm 50 in the second path. However, it is not limited to this. For example, when the first guide 68 is in the first posture, the tip 73 of the first guide 68 may be positioned downstream of the detection arm 50 in the second path. In that case, when the first guide 68 is in the second posture, the recording paper is located on the lower side in the vertical direction different from the second path 33 between the tip of the detection arm 50 and the upper surface 71 of the first guide 68. The position of the detection arm 50, that is, the position of the rotation center shaft 51 is determined so that a gap through which 16 can pass is formed. In other words, when the first guide 68 is in the second posture, the position where the gap through which the recording paper 16 can pass is formed between the tip of the detection arm 50 and the upper surface 71 of the first guide 68. The position of the detection arm 50 is determined as the most upstream side of the position of the detection arm 50 in the path 33. In other words, when the first guide 68 is in the second posture, the gap between the tip of the detection arm 50 and the upper surface 71 of the first guide 68 that allows the recording paper 16 to pass is formed. The position of the first arm 50 is determined so as to be downstream of the second path.

[Third guide]

A third guide 100 that is rotatable about the shaft 27 of the paper feed roller 25 is provided on the downstream side of the second path 33 in the second conveyance direction. The third guide 100 is disposed downstream of the detection arm 50 in the second direction of the second path 33 in the transport direction. The third guide 100 is formed in a flat plate shape. The third guide 100 is rotatable about the shaft 27. When the paper feed cassette 15 is mounted, the third guide 100 constitutes a part of the wall surface defining the second path 33 as shown in FIG. Yes. In a state in which the paper feed cassette 15 is detached, the second path 33 can be opened by rotating counterclockwise about the shaft 27 as shown in FIG.

[Control unit]

  FIG. 7 is a block diagram illustrating a configuration of the control unit 90 of the multifunction machine 10. The control unit 90 controls the overall operation of the multifunction machine 10, but detailed description of the control of the scanner unit 12 and the recording unit 24 is omitted. The control unit 90 includes a CPU 91 that performs arithmetic processing, a ROM 92 that stores a control program, a RAM 93 that is used as a data storage area or a work area, and an EEPROM 94 that stores setting information and the like. It is configured as a microcomputer. Each component is connected via a bus 95 so that data can be transferred.

  A drive circuit 96 is connected to the bus 95. The drive circuit 96 drives the LF motor 85 and the ASF motor 86. The LF motor 85 is connected to the transport roller 35, the paper discharge roller 39, the switchback roller 32, and the like, and drives them. The ASF motor 86 drives the paper feed rollers 25 and 28. The drive circuit 96 includes a driver for driving the LF motor 85 and the ASF motor 86, and the LF motor 85 and the ASF motor 86 are independently controlled by these drivers. The driving force of the LF motor 85 is transmitted to the transport roller 35, the paper discharge roller 39, and the switchback roller 32 via a known drive transmission mechanism. The rotational force of the ASF motor 86 is also transmitted to the paper feed rollers 25 and 28 via the drive transmission mechanism described above.

  In the multifunction machine 10 according to the present embodiment, the LF motor 85 is a drive source for the transport roller 35 and the paper discharge roller 39. Accordingly, the recording paper 16 is transported toward the platen 36, and the recording paper 16 positioned on the platen 36 and the recorded recording paper 16 are transported in the first transport direction. Further, the LF motor 85 also serves as a drive source for normal and reverse rotation of the switchback roller 32. When an image is recorded on the back surface of the recording paper 16, the LF motor 85 is reversed by the switchback roller pair 43. To the second path 33. Specifically, the recorded recording paper 16 is transported in the first transport direction by the forward rotation of the switchback roller 32. Then, when the second end of the recording paper 16 reaches the stop position 90, the reverse rotation of the switchback roller 32 is started.

  The rotary encoder 97, the optical sensor 56, and the registration sensor 34 are connected to the bus 95. The rotary encoder 97 detects the amount of rotation of the switchback roller 32 driven by the LF motor 85 and is attached to the casing 72 of the printer unit 11. Based on the level of the output signal of the optical sensor 56 and the encoder amount detected by the rotary encoder 97, the control unit 90 determines whether or not the recording paper 16 is present in the transport path 31 and the second path 33 and the leading or trailing edge of the recording paper 16. The position and the conveyance amount of the recording paper 16 are grasped. Note that encoder amounts corresponding to the distances D1 and D2 are recorded in the EEPROM 94. Therefore, the CPU 91 can determine whether the transport amount of the recording paper 16 that is switched back and sent to the second pass 3 exceeds the distances D1 and D2.

[Inserting and unloading paper cassettes and transporting recording paper]

As shown in FIGS. 2 and 3, the multifunction machine 10 is in a state in which the recording paper 16 can be fed to the conveyance path 31 when the paper feed cassette 15 holding the recording paper 16 is attached. At this time, the first guide 68 is displaced to the first posture, and the second path 33 is partitioned. When the LF motor 85 is driven and the switchback roller 32, the conveyance motor 35, and the paper discharge roller 39 are rotated forward, the recording paper 16 is conveyed in the first conveyance direction along the conveyance path 31 with the first end as the head. . The recording sheet 16 conveyed along the conveyance path 31 records an image on the first surface by the recording unit 17. When an image is also recorded on the second surface of the recording paper 16, the switchback roller 32 reverses and the recording paper 16 is sent to the second path 33 with the second end as the head. When the recording paper 16 enters the second path 33, the recording paper 16 comes into contact with the detection arm 50, and the detection arm 50 is pushed down by the recording paper 16 and falls down from the second path 33. Thus, the presence of the recording paper 16 is detected by the sheet detection mechanism 47, and it is determined that the recording paper 16 is normally conveyed along the second path 33. The recording paper 16 sent to the second path 33 is returned to the transport path 21 and the transport path 31 again starting from the second end, and an image is recorded on the second surface by the recording unit 17.

  When the paper feed cassette 15 is removed, the first guide 68 changes to the second posture as shown in FIG. That is, the first guide 68 is rotated downward in the vertical direction, and the wall surface on the lower side in the vertical direction that defines the second path 33 is rotated downward in the vertical direction to open the second path 33. Thus, when the first guide 68 changes its posture, the user can easily perform so-called jam processing when a jam occurs in the second pass 33.

  It is assumed that the paper feed cassette 15 is removed during the conveyance of the recording paper 16. In that case, the recording paper 16 sent to the second path 33 falls from the opened second path 33, and therefore jamming occurs. More specifically, the recording paper 16 passes through a gap between the tip 73 of the first guide 68 and the wall surface 74 of the second path 33 and falls downward in the vertical direction different from the second path 33. If the recording paper 16 continues to be fed by the switchback roller 32 in this state, the jammed state may deteriorate and the recording paper 16 may be damaged. However, in this embodiment, when the recording paper 16 moves outside the second path 33, the sheet detection mechanism 47 does not come into contact with the detection arm 50, so that the sheet detection mechanism 47 does not move even though the switchback roller 32 repeats reverse rotation. The recording paper 16 is not detected.

  Specifically, if the optical sensor 56 does not output an ON / OFF switching signal when the recording paper 16 is sent by the switchback roller 32 in the second direction of conveyance in the second direction, the recording paper 16 is in the second state. It can be determined that the vehicle has left the path 33. This is because the detection arm 50 is disposed at a position where the relationship of D1 <D2 is established with respect to the distances D1 and D2, and therefore, if the first guide 68 is in the second posture, the recording paper 16 is in the second path 33. This is because it is expected to have moved to the outside and reached the virtual plane 76. Note that the conveyance amount of the recording paper 16 is grasped by the encoder amount of the rotary encoder 97 (that is, corresponding to the rotation speed of the switchback roller 32) as described above.

  In such a case, the control unit 90 can stop the driving of the LF motor 85 based on the rotation speed of the switchback roller 32. If the conveyance is stopped when the recording paper 16 is sent by the distance D2, it is prevented that the jamming state of the recording paper 16 deteriorates and the recording paper 16 is damaged. In the present embodiment, the distances D1 and D2 are stored in advance, and the driving of the LF motor 85 is stopped based on the encoder amount corresponding to these distances. Therefore, the rotation control of the switchback roller 32 is very simple.

Note that the rotation control of the switchback roller 32 can also be performed by the driving time of the LF motor 85. That is, the control unit 90 stops the LF motor 85 when the detection arm 50 does not detect the presence of the recording paper 16 even if a predetermined time has elapsed after the switchback roller 32 is reversed. This prevents the recording paper 16 jam condition from deteriorating. The fixed time in this case is a time until the transport distance of the recording paper 16 switched back exceeds the distance D1 and is expected to reach the distance D2. This time is set in advance and stored in the EEPROM 94.

  In the present embodiment, since the drive shaft 70 that supports the first guide 68 is disposed at the above-described position, the recording paper 16 must always be in the second pass when the first guide 68 is changed to the second posture. Leave from 33. Therefore, it is possible to prevent the jam from occurring in the second path 33 when the paper feed cassette 15 is removed, and to reliably prevent the jam from deteriorating.

  In addition, as described above, when the paper feeding cassette 15 is removed while the recording paper 16 is being conveyed, the recording paper 16 sent to the second path 33 moves to the outside of the second path 33. It should be. However, for example, the recording paper 16 may reach or come into contact with the detection arm 50 even though the second path 33 is opened due to the rigidity of the recording paper 16 (so-called waist strength). In this case, if the detection arm 50 is easily submerged from the second path 33, it is erroneously detected as normal conveyance even though the second path 33 is opened. Then, the recording paper 16 may move to the outside of the second path 33 after being normally detected by the sheet detection mechanism 47, and the jam state of the recording paper 16 will be deteriorated. However, in the present embodiment, since the detection arm 50 is biased so as to protrude with respect to the second path 33, such erroneous detection is suppressed. Further, in a state where the paper feed cassette 15 is removed, the downstream side of the second path 33 in the second conveyance direction is opened by the third guide 100. Therefore, even if the recording paper 16 reaches the detection arm 50, the recording paper 16 is jammed because the second path 33 is opened by the third guide 100. However, in the present embodiment, the detection arm 50 is urged so as to protrude with respect to the second path 33. Therefore, when the paper feed cassette 15 is removed, a jam can be detected at an early stage. It becomes possible.

  Further, in the present embodiment, since the second guide 44 and the detection arm 49 are provided, the recording paper 16 on which the image is recorded on the first surface is supported by the guide support surface 45 of the second guide 44. It is sent in the first direction of conveyance. When the recording paper 16 comes into contact with the detection arm 49, it is detected that the recording paper 16 is conveyed along the conveyance path 31. Therefore, the switchback timing of the recording paper 16 can be accurately controlled.

  Further, since the detection arms 49 and 50 are provided on the rotation center shaft 51, the detection arms 49 and 50 operate simultaneously when the rotation center shaft 51 rotates. Accordingly, the sheet detection mechanism 47 outputs a detection signal when the recording paper 16 is transported along the transport path 31 and along the second path 33. That is, since it is detected by the single optical sensor 56 that the recording paper 16 has been transported along both the transport path 31 and the second path 33, the structure of the sheet detection mechanism 47 is simplified.

DESCRIPTION OF SYMBOLS 10 ... Multifunction machine 11 ... Printer part 16 ... Recording paper 17 ... Recording part 21 ... Conveyance path 23 ... Conveyance path 31 ... Conveyance path 32 ... Switchback roller 33 ... Second pass 43 ... Switchback roller pair 44 ... Second guide 45 ... Guide support surface 46 ... Recess 47 ... Sheet detection mechanism 48 ... Branch port 49 ... Detection arm 50... Detection arm 51... Rotation center axis 52... Rotation wheel 56... Optical sensor 63 ... Flap 64 ... Shaft 67 ... Second auxiliary roller 68. -1st guide 70 ... Drive shaft 72 ... Case 73 ... Tip 74 ... Wall surface 75 ... Upper surface 76 ... Virtual plane 90 ... Control part

  The present invention relates to an image recording apparatus for recording an image on a sheet, and more particularly to an image recording apparatus capable of recording an image on both a first surface (front surface) and a second surface (back surface) of a sheet. Is.

  There is known an image recording apparatus capable of recording images on both front and back surfaces of a sheet (typically recording paper) (see, for example, Patent Document 1). In the image recording apparatus disclosed in Patent Document 1, a recording sheet pulled out from a paper feed tray is transported along a transport path, and an image is recorded on the surface. The recording sheet having the image recorded on the front side is sent to the reverse path and turned upside down, and then returned to the transport path to record the image on the back side. In the image recording apparatus disclosed in this document, a part of the reversing path can be opened and closed, and the reversing path is opened and closed in conjunction with the attachment and detachment of the paper feed tray.

JP 2008-213981 A

An object of the present invention, when the jam had us to inversion path occurs is that the user provides an image recording apparatus capable of easily jam.

  (1) An image recording apparatus according to the present invention includes a sheet cassette that holds a sheet fed in a first direction along a first path starting from a first end, and the first path from the sheet cassette. An image is recorded on the first surface of the sheet sent to the sheet, and the sheet is returned from the first pass to the first pass again through the second pass starting from the second end opposite to the first end. A recording unit for recording an image on the second surface of the recording medium, and a downstream of the first pass to the second pass, the first direction downstream in the transport direction, and transports the sheet by normal rotation or reverse rotation. A first roller that is conveyed in the first direction or a second direction in the conveying direction, and a first arm that can be projected and retracted in the second path, and the first arm is in contact with the sheet conveyed along the second path. Conveyance detection that detects the sheet by Means, a first guide that extends obliquely downward from the branch port toward the downstream side of the second path and that is provided to be rotatable about a support shaft, and a sheet on which an image is recorded on the first surface When the conveyance detecting means does not detect the sheet even when a distance necessary to reach at least the first arm in the second direction of conveyance along the second path by reversing the conveyance roller, A controller that stops the conveying roller, and the first guide forms a lower wall surface in the vertical direction that defines the second path by mounting the sheet cassette, and the conveying direction is determined by the conveying roller. A first posture for guiding the sheet conveyed in the second direction along the second path, and the sheet cassette is rotated to rotate vertically downward about the support shaft when the sheet cassette is detached. So that the seat is separated from the second path and the posture of the second path is changed to a second position that opens upstream from the first arm of the second path so that contact between the seat and the first arm is avoided. It is configured.

  According to this configuration, when the sheet cassette holding the sheet is mounted, the sheet can be fed to the first path, and at the same time, the first guide is displaced to the first posture and the second path is partitioned. The When the conveying roller rotates forward, the sheet is conveyed in the first direction along the first path with the first end as the head, and an image is recorded on the first surface by the recording unit. When an image is also recorded on the second surface of the sheet, the conveyance roller reverses and the sheet is conveyed in the second direction of conveyance starting from the second end. When the sheet enters the second path, the sheet comes into contact with the first arm, and the first arm is pushed by the sheet and sunk from the second path. Thereby, the presence of the sheet is detected by the conveyance detection unit, and it can be determined that the sheet is normally conveyed along the second path. The sheet sent to the second path is conveyed again in the first direction in the conveying direction along the first path with the second end as the head, and an image is recorded on the second surface by the recording unit.

  When the sheet cassette is removed, the first guide changes to the second posture. As a result, the first guide that has formed the wall surface on the lower side in the vertical direction that divides the second path rotates downward in the vertical direction, and the second path is opened. Thus, when the first guide changes its posture, the user can easily perform so-called jam processing when a jam occurs in the second pass.

  By the way, the sheet cassette may be removed while the sheet is being conveyed, either intentionally or unintentionally by the user. In that case, the sheet sent to the second path leaves the second path downward in the vertical direction and moves to the outside of the second path, so that a jam occurs. If the sheet continues to be fed in the second direction in the conveying direction in this state, the jammed state may deteriorate and the sheet may be damaged. However, when the sheet moves to the outside of the second pass, the sheet moves to the outside of the second pass while avoiding contact with the first arm. Regardless, a state occurs in which the conveyance detection unit does not detect the presence of the sheet. The control unit stops the conveyance roller when the conveyance detection unit does not detect the presence of the sheet even if a predetermined time elapses after the conveyance roller is reversed. This prevents the jammed state of the sheet from getting worse.

  (2) The first arm is a gap formed between the front end of the first arm and the wall surface when the first guide is changed to the second posture, and the first arm is vertically downward. It is preferable that the sheet is allowed to pass and is arranged on the downstream side of the second path from the position of the gap different from the second path.

  In this configuration, when the first guide changes to the second posture, the sheet always leaves the second path. Therefore, even if the sheet cassette is removed and a jam occurs, the deterioration of the jam is surely prevented.

  (3) The apparatus may further include a contact portion that is disposed vertically below the second path and contacts the bottom surface of the sheet cassette when the sheet cassette is mounted. The sheet cassette is mounted between the second path and the contact portion, and the first arm starts to reverse the conveying roller when the first guide is in the first posture. The distance from when the sheet is conveyed by the reverse rotation of the conveying roller until the sheet reaches the first arm along the second path is D1, and the first guide is in the second posture. The distance from when the reverse rotation of the conveyance roller is started until the sheet conveyed by the reverse rotation of the conveyance roller leaves the second path and reaches the virtual plane including the contact portion is defined as D2. In this case, it is preferable that the lens is disposed at a position where the relationship of D1 <D2 is established.

  In this configuration, when the sheet is sent by the distance D2 in the second direction of conveyance by the reverse rotation of the conveyance roller, the sheet is separated from the second path when the conveyance detection unit does not detect the sheet. Can be determined. Therefore, the control unit can stop the conveyance roller based on the rotation number of the conveyance roller, and the rotation control of the conveyance roller is simplified. In addition, since the first arm is disposed at a position where the relationship of D1 <D2 is established, if the first guide is in the second posture, the sheet moved to the outside of the second path is in contact with the second path. The transport roller is stopped before reaching the virtual plane including the portion. That is, the transport roller is stopped in a state where the leading edge of the sheet is in the mounting area of the sheet cassette. Therefore, when the first guide is in the second posture, the seat is prevented from buckling against the contact portion or the like.

  (4) It is preferable that a biasing member that biases the first arm so as to protrude with respect to the second path is further provided.

  If the sheet cassette is removed while the sheet is being conveyed as described above, the sheet sent to the second pass should move to the outside of the second pass. However, for example, the sheet may reach the first arm even though the second path is opened due to the rigidity of the sheet (so-called seat waist). In this case, if the first arm is easily submerged from the second pass, it is detected as normal sheet conveyance even though the second pass is released. Then, the sheet may move to the outside of the second path after being detected by the conveyance detection unit. In this case, if the sheet continues to be fed in the second direction of conveyance, the jammed state of the sheet deteriorates. Resulting in. However, in the present invention, since the first arm is biased so as to protrude with respect to the second path, such erroneous detection is suppressed.

  (5) Provided downstream of the recording unit in the first direction of conveyance, supports the second surface of the sheet on which the image is recorded on the first surface by the recording unit, and moves the sheet in the first direction of conveyance. A second guide having a guide support surface for guiding may be further provided. The conveyance detection means has a second arm that can protrude and retract from the guide support surface with respect to the first path on the downstream side in the first conveyance direction from the recording portion of the first path, and an outer peripheral surface. And a rotation center shaft on which the first arm and the second arm protrude from the outer peripheral surface, and the sheet conveyed along the first path or the second path is the first arm or It is preferable that the sheet conveyed along the first path or the second path is detected by rotating the rotation center axis in contact with the second arm.

  The sheet on which the image is recorded on the first surface is fed in the first direction of conveyance while being supported by the guide support surface of the second guide. When the sheet comes into contact with the second arm, the conveyance detection unit detects that the sheet is conveyed along the first path. Thereby, when the image is recorded on the second surface, the switchback of the sheet, that is, the reverse timing of the transport roller in the transport direction second direction can be accurately controlled.

  The first arm and the second arm are operated simultaneously by the rotation of the rotation center axis. Therefore, when a sheet having an image recorded on the first surface is conveyed along the first path, the sheet comes into contact with the second arm, and the conveyance detection unit outputs a detection signal. When the sheet having an image recorded on the first surface is conveyed along the second path in the second direction of conveyance, the sheet comes into contact with the first arm, and the conveyance detection unit outputs a detection signal. . As described above, since it is detected by the single sensor that the sheet is conveyed in both the first pass and the second pass, the structure of the conveyance detection unit is extremely simplified.

  (6) The image recording apparatus rotates between a state in which the second pass is partitioned by mounting the sheet cassette and a state in which the second path is opened by removing the sheet cassette. It is preferable to provide a moving third guide.

(7) It is preferable that the third guide is rotatably provided on the downstream side of the second path with respect to the first arm.

  According to the present invention, it is possible to detect the deterioration of the jam state in the second pass with a simple and inexpensive structure, and it is possible to prevent the sheet from being damaged.

FIG. 1 is an external perspective view of a multifunction machine 10 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the multifunction machine 10. FIG. 3 is an enlarged view of a main part in FIG. FIG. 4 is a perspective view of the second guide 44 provided in the multifunction machine 10. FIG. 5 is an enlarged view of a main part in FIG. FIG. 6 is a cross-sectional view of a main part of the multifunction machine 10 with the first guide 68 opened. FIG. 7 is a block diagram illustrating a configuration of the control unit 90 of the multifunction machine 10.

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

[Schematic configuration of MFP 10]

  FIG. 1 is an external perspective view of a multifunction machine 10 according to an embodiment of the present invention. As shown in the figure, the multifunction machine 10 is integrally provided with a printer unit 11 and a scanner unit 12, and has a print function, a scan function, a copy function, and a facsimile function. The printer unit 11 corresponds to the image recording apparatus according to the present invention. The multifunction machine 10 does not necessarily have the scanner unit 12, and the image recording apparatus according to the present invention may be implemented as a single-function printer that does not have a scanner function or a copy function. Therefore, description of the detailed configuration of the scanner unit 12 is omitted.

A printer unit 11 is provided in the lower part of the multifunction machine 10. An opening 13 is formed on the front side of the printer unit 11. The paper feed cassette 14 and the paper feed cassette 15 are mounted on the printer unit 11 through the opening 13. The paper feed cassettes 14 and 15 can hold a regular rectangular recording paper 16 (corresponding to a “sheet” recited in the claims: see FIG. 3). The recording paper 16 is selectively supplied into the printer unit 11 from the paper feed cassette 14 or the paper feed cassette 15. The recording paper 16 supplied to the printer unit 11 is discharged onto the upper surface 18 of the paper feed cassette 15 after an image is recorded by the recording unit 17 (see FIG. 2). Therefore, the upper surface 18 of the paper feed cassette 15 functions as a paper discharge tray.

  An operation panel 19 is provided in the upper front portion of the multifunction machine 10. The operation panel 19 includes a display that displays various types of information and an input key that receives input of information. The multifunction device 10 operates based on instruction information input from the operation panel 19 or instruction information transmitted from an external information device through a printer driver, a scanner driver, or the like.

[Printer section]

  As shown in FIG. 2, the paper feed cassette 14 and the paper feed cassette 15 (corresponding to “sheet cassette” described in the claims) are arranged in two upper and lower stages with the paper feed cassette 15 as the upper side. Each of the paper feed cassettes 14 and 15 holds a recording paper 16 on which image recording is performed. By providing two independent paper feed cassettes 14 and 15, recording paper 16 having a different size and paper type can be held.

  The paper feed cassette 14 is formed in a box shape, and a part of the rear upper side (left side in FIG. 2) of the multifunction machine 10 is opened. The recording paper 16 is placed inside the paper feed cassette 14 in a stacked state. The paper feed cassette 14 can accommodate recording papers 16 of various sizes such as A4 size, B5 size, and postcard size, for example, A3 size or smaller. The paper feed cassette 15 is also a box-like shape in which a part on the upper rear side of the multifunction machine 10 is opened, and recording paper 16 of various sizes can be accommodated in the paper feed cassette 15. The upper surface 18 of the paper feed cassette 15 is provided on the front side (the right side in FIG. 2) of the multifunction machine 10.

  A curved conveyance path 21 is formed above the inclined plate 20 of the paper feed cassette 15. When the paper feed cassette 15 is attached to the printer unit 11, the inclined plate 20 is disposed below the conveyance path 21, and the paper feed roller 25, the arm 26, and the shaft 27 are disposed above the paper feed cassette 15. The paper feed roller 25 is rotatably provided on the tip side of the arm 26. The arm 26 is rotatably supported by a shaft 27, and the shaft 27 is supported by a housing 72 of the printer unit 11. The arm 26 is urged to rotate toward the sheet feeding cassette 15 by its own weight or by receiving an elastic force from a spring or the like.

  A curved conveyance path 23 is formed on the upper side of the inclined plate 22 of the paper feed cassette 14. When the paper feed cassette 14 is attached to the printer unit 11, the inclined plate 22 is disposed below the conveyance path 23, and the paper feed roller 28, the arm 29, and the shaft 30 are disposed above the paper feed cassette 14. The paper feed roller 28 is rotatably provided on the tip end side of the arm 29. The arm 29 is rotatably supported by the shaft 30, and the shaft 30 is supported by the casing 72 of the printer unit 11. The arm 29 is urged to rotate toward the sheet feeding cassette 14 by its own weight or by receiving an elastic force from a spring or the like.

[First pass / Second pass]

  FIG. 3 is an enlarged view of a main part in FIG. A conveyance path 31 that is continuous with the conveyance path 23 and the conveyance path 21 is formed inside the printer unit 11. In addition, the conveyance path 23, the conveyance path 21, and the conveyance path 31 correspond to the “first path” recited in the claims. The conveyance path 31 is a path for further conveying the recording paper 16 conveyed along the conveyance path 23 or the conveyance path 21 to the right side in FIG. The conveyance path 31 extends from the position where the conveyance path 23 and the conveyance path 21 merge toward the front side of the multifunction machine 10 and above the upper surface 18 of the sheet feeding cassette 15. The direction from the position where the conveyance path 23 and the conveyance path 21 merge to the front side of the multifunction machine 10 is the “first direction in the conveyance direction”.

  A second path 33 is formed by branching from the downstream side of the conveyance path 31 (upstream side of a switchback roller 32 described later). As shown in the drawing, the second path 33 is connected to the upstream side of the first path (upstream side of the transport path 31). As a result, the multifunction device 10 can record the image on both the front and back sides of the recording paper 16 by turning the recording sheet 16 upside down. Specifically, the second path 33 forms a branch port 48 at an upstream position of the switchback roller 32 (corresponding to “carrying roller” recited in the claims), and the branch port 48 and the conveyance path 31. Is connected to the upstream side.

  The recording paper 16 pulled out from the paper feed trays 14 and 15 is transported along the transport path 23 (transport path 21) and the transport path 31 with the first end (for example, the front end) as the head, and is recorded on the first surface by the recording unit 17. An image is recorded (for example, on the surface). When an image is also recorded on the back side, the recording paper 16 is switched back from the transport path 31 to the second path 33 with the second end (rear end) as the head, and returned to the transport path 31 again. As a result, the recording paper 16 is turned upside down, and an image is recorded on the back side by the recording unit 17.

  A registration sensor 34 is disposed on the upstream side of the conveyance path 31. Specifically, a registration sensor 34 is provided on the upstream side in the first conveyance direction of a conveyance roller 35 described later. The registration sensor 30 detects the presence or absence of the recording paper 16 that passes through the conveyance path 31. Whether the leading edge or the trailing edge of the recording paper 16 has reached the position where the registration sensor 30 is provided is determined based on the ON / OFF signal change from the registration sensor 30.

[Platen / Recording section]

  As shown in FIGS. 2 and 3, a platen 36 is provided in the conveyance path 31. The platen 36 supports the recording paper 16 conveyed along the conveyance path 31 from below. The recording unit 17 is disposed above the platen 36. The upper surface of the platen 36 is colored so as to have a reflectance different from that of the recording paper 16. Since the recording paper 16 is usually white, the upper surface of the platen 36 is typically colored black.

  The recording unit 17 includes a carriage 24 disposed on the upper side of the conveyance path 31 and a platen 36 disposed on the lower side. The carriage 24 has an inkjet recording head 80 mounted thereon. The ink jet recording head 80 is disposed opposite to the platen 36, and minute ink is directed toward the platen 36 when the carriage 24 is reciprocated in a direction perpendicular to the first direction of conveyance (direction perpendicular to the paper surface). Drops are selectively ejected. The ejected ink droplets land on the recording paper 16 supported by the platen 36. In this way, a desired image is recorded on the recording paper 16 by alternately conveying the recording paper 16 and reciprocating the carriage 24.

[Feed roller pair]

  A feed roller pair 37 is arranged along the transport path 31 on the upstream side in the first transport direction with respect to the platen 36. The feed roller pair 37 includes a transport roller 35 and a pinch roller 38. The conveyance roller 35 is disposed on the upper side of the conveyance path 31 and rotates by the driving force transmitted from the LF motor 85 (see FIG. 7). The pinch roller 38 is rotatably disposed below the conveyance roller 35 with the conveyance path 31 interposed therebetween, and is urged toward the conveyance roller 35 by a spring. The holding force of the recording paper 16 by the conveying roller 35 and the pinch roller 38 is stronger than the holding force by the switchback roller 35 and the spur 41. Note that the holding force of the recording paper 16 by the conveying roller 35 and the pinch roller 38 is stronger than the holding force by the discharge roller 39 and the spur 40 described later, and the holding force by the discharge roller 39 and the spur 40 is the switchback roller. It is stronger than the clamping force by 35 and the spur 41.

[Discharge roller pair]

  A discharge roller pair 42 is provided on the downstream side of the platen 36 in the first conveyance direction. The discharge roller pair 42 includes a discharge roller 39 and a spur 40. The paper discharge roller 39 is rotated by the driving force transmitted from the LF motor 85 (see FIG. 7). The spur 40 is rotatably disposed above the paper discharge roller 39 with the conveyance path 31 interposed therebetween, and is urged by a spring toward the paper discharge roller 39. Since the paper discharge roller 39 and the spur 40 sandwich the recording paper 16 after image recording, the clamping force is set to be weaker than the clamping force of the recording paper 16 by the transport roller 35 and the pinch roller 38.

[Switchback roller pair]

  A switchback roller pair 43 is provided downstream of the discharge roller pair 42 in the first direction of conveyance. The switchback roller pair 43 includes a switchback roller 32 and a spur 41. The switchback roller 32 is rotated by the driving force transmitted from the LF motor 85 (see FIG. 7). The spur 41 is rotatably disposed above the switchback roller 32 with the conveyance path 31 in between, and is urged by a spring toward the switchback roller 32. The switchback roller 32 can rotate forward and backward. As the switchback roller 32 rotates forward, the recording paper 16 is conveyed in the first direction of conveyance and is discharged to the upper surface 18 of the paper feed tray 15. As the switchback roller 32 rotates in the reverse direction, the recording paper 16 is conveyed in the second direction of conveyance opposite to the first direction of conveyance. That is, the recording paper 16 is switched back. The holding force of the switchback roller 32 and the spur 41 may be set to be smaller than the holding force of the feed roller pair 37 and the discharge roller pair 42 as long as it is sufficient to discharge or switch back the recording paper 16. ing.

[Second Guide / Sheet Detection Mechanism]

  A second guide 44 is disposed between the discharge roller pair 42 and the switchback roller pair 43. The second guide 44 extends substantially horizontally along the transport direction. The second guide 44 includes a guide support surface 45, and this guide support surface 45 defines a part of the transport path 31. The recording paper 16 is guided downstream while being supported by the guide support surface 45. The second guide 44 is provided with a recess 46. The recess 46 is a groove opened in the guide support surface 45 and extends in the transport direction. The function of this groove will be described later.

  FIG. 4 is a perspective view of the second guide 44. FIG. 5 is an enlarged view of a main part in FIG. The second guide 44 is provided with a sheet detection mechanism 47 (corresponding to “conveyance detection means” described in claims). The conveyance detection mechanism 47 detects the presence or absence of the recording paper 16 passing through the conveyance path 31 or the second path 33 (see FIG. 3). The sheet detection mechanism 47 includes a rotation center shaft 51, a detection arm 49 (corresponding to “second arm” recited in claims), a detection arm 50 (corresponding to “first arm” recited in claims), The optical sensor 56 (refer FIG. 7: photo interrupter, for example) and the rotation wheel 52 (equivalent to the "biasing means" described in the claim) are provided. When the recording paper 16 is transported along the transport path 31 and transported along the second path 33 (see FIG. 3), the detection arm 49 and the detection arm 50 fall down in the transport direction. The optical sensor 56 detects this and outputs an on / off signal. Thereby, it is determined whether the leading edge or the trailing edge of the recording paper 16 has reached the position where the detection arm 49 or the detection arm 50 is provided.

  As shown in FIG. 4, the rotation center shaft 51 is a rod-shaped member made of resin. The rotation center shaft 51 extends in a direction intersecting with the conveyance direction of the recording paper 16. The rotation center shaft 51 is supported by the guide member 44. As shown in the figure, a pair of support plates 53 project from the inner wall of the guide member 44. The support plate 53 is formed integrally with the guide member 44. Both ends of the rotation center shaft 51 are rotatably supported by the support plate 53.

  A detection arm 49 protrudes from one end side of the rotation center shaft 51. The detection arm 49 protrudes from the outer peripheral surface of the rotation center shaft 51 and extends in the radial direction. Accordingly, the detection arm 49 penetrates the second guide 44 upward and is exposed in a standing state at the center of the guide support surface 45. The detection arm 50 is also provided on the outer peripheral surface of the rotation center shaft 51. The detection arm 50 is disposed so as to substantially face the detection arm 49, and extends in the radial direction of the rotation center shaft 51. Accordingly, the detection arm 50 penetrates the lower surface 54 of the second guide 44 downward and protrudes downward from the center of the lower surface 54. A slit 55 is provided in the guide support surface 45 and the lower surface 54 of the second guide 44. The detection arm 49 and the detection arm 50 are inserted into the slit 55, and the detection arm 49 and the detection arm 50 can fall down along the slit 55 as the rotation center shaft 51 rotates.

  As shown in FIGS. 4 and 5, a notch 57 is provided in the lower portion of the second guide 44. The notch 57 is provided on the lower surface 54 of the second guide 44 and is cut from the downstream edge 62 of the second path 33 to the upstream side of the second path 33. The wall surface that defines the cutout 57 forms the cutout 57 in a rectangular shape. The dimension in the width direction 48 of the notch portion 57 is set to be larger than the dimension in the width direction 48 of the rotation wheel 52, and the rotation wheel 52 can be moved forward and backward with respect to the notch portion 57. When the rotating wheel 52 enters the notch portion 57, it comes into contact with the inner back wall 59 (corresponding to the “contact portion” described in the claims) that defines the notch portion 57. That is, the inner back wall 59 abuts on the turning wheel 52 and restricts the entry of the turning wheel 52.

  The rotation wheel 52 is provided at the other end of the rotation center shaft 51. That is, the rotation wheel 52 is arranged at a position different from the detection arm 49 and the detection arm 50 with respect to the axial direction of the rotation center shaft 51. The rotation wheel 52 may be formed integrally with the rotation center shaft 51 or may be fixed to the rotation center shaft 51 by a known fixing means. In the present embodiment, the rotation wheel 52 is made of a substantially fan-shaped plate member and protrudes in the radial direction of the rotation center shaft 51. Since the rotation wheel 52 protrudes in the radial direction of the rotation center shaft 51, the rotation center shaft 51 receives a moment due to the weight of the rotation wheel 52. The direction of this moment is the direction of the arrow 61 in FIG.

  Therefore, in FIG. 3, the rotation center shaft 51 is always urged to rotate counterclockwise, and the detection arm 49 is always raised from the guide support surface 45 (that is, rotated upstream in the first direction in the transport direction). Further, the detection arm 50 is biased so as to always protrude downward from the lower surface 54 of the guide member 44 (that is, to rotate upstream in the transport direction of the second path 33). However, as shown in FIG. 5, the rotation wheel 52 abuts on the inner back wall 59, so that the rotation center shaft 51 is rotated counterclockwise (in the direction of the arrow 61), but the inner back wall 59. Rotation is regulated by. That is, the detection arm 49 is restricted from falling from the posture shown in FIG. 3 to the upstream side in the first conveyance direction of the conveyance path 31, and the detection arm 50 is conveyed from the posture shown in FIG. 3 in the conveyance direction of the second path 33. It is restricted to fall to the upstream side.

  As shown in FIG. 3, when the recording paper 16 is transported along the transport path 31 in the first transport direction, the recording paper 16 moves the detection arm 49 after passing the guide support surface 45 of the second guide 44. The rotation center shaft 51 is rotated by receiving a clockwise moment (in the direction of arrow 60 in FIG. 5) in FIG. Thereby, the rotation wheel 52 is retracted from the notch portion 57 in FIG. 5, and the detection arm 49 is laid down downstream in the first direction of conveyance. Since the detection arm 49 falls down, the recording paper 16 is smoothly fed along the transport path 31. When the recording paper 16 is switched back and conveyed along the second path 33, the detection arm 50 is pressed, and the rotation center axis 51 is rotated clockwise in FIG. 3 (indicated by the arrow 60 in FIG. 5). Direction) and rotate. As a result, the rotation wheel 52 is retracted from the notch 57 in FIG. Since the detection arm 50 is laid down, the recording paper 16 is smoothly fed along the second path 33 and enters the transport path 21 again.

  The optical sensor 56 is disposed inside the second guide 44, and the photo interrupter is fixed to the second guide 44. The photo interrupter is disposed at a position crossed by a rotation wheel 52 that rotates in conjunction with the rotation of the rotation center shaft 51. The optical sensor 56 is configured to be turned on or off when the rotating wheel 52 crosses the photo interrupter.

[flap]

  As shown in FIGS. 2 and 3, a flap 63 is provided between the discharge roller pair 42 and the switchback roller pair 43 along the first path 22. The flap 63 is rotatably supported on the shaft 64. The shaft 64 is arranged on the discharge roller pair 42 side (upstream side in the first conveyance direction) from the branch port 48. The flap 63 includes a frame 65 and a first auxiliary roller 66 and a second auxiliary roller 67 provided on the frame 65. A base end portion of the frame 65 is supported by the shaft 64, and the frame 65 extends along the transport path 31 in the first transport direction. The first auxiliary roller 66 is rotatably disposed at a substantially central portion of the frame 65, and is disposed downstream of the shaft 64 in the first conveyance direction. Further, the second auxiliary roller 67 is rotatably disposed at the distal end portion of the frame 65.

  As shown in FIG. 6, the first auxiliary roller 66 can be fitted into the recess 46 provided in the second guide 44 when the frame 65 rotates around the support shaft 66. That is, the flap 63 rotates clockwise about the shaft 64 in FIG. 3, and the first auxiliary roller 66 can enter the recess 46. The posture of the flap 63 at this time is defined as the approach posture. As shown in FIG. 3, the flap 63 rotates counterclockwise about the shaft 64, and the first auxiliary roller 66 can be retracted from the recess 46. The posture of the flap 63 at this time is defined as the exit posture.

  At all times, the flap 63 is in the approach posture due to its own weight. When the recording paper 16 is transported on the guide support surface 45 along the transport path 31 downstream in the first transport direction, the recording paper 16 and the first auxiliary roller 66 are pushed up. As a result, the flap 63 changes to the retracted posture, and the recording paper 16 is further sent downstream in the first direction of conveyance. As the recording paper 16 is transported, the recording paper 16 is sandwiched between the switchback roller pair 43 and further fed in the first transport direction. When the recording paper 16 passes through the first auxiliary roller 66, the first auxiliary roller 66 is fitted into the recess 46, so that the flap 63 changes to the approaching posture.

  When the flap 63 is in the approach posture, the second auxiliary roller 67 presses the second end side of the recording paper 16 downward, and the second end of the recording paper 16 is corrected in the direction of the second path 33. If double-sided recording is not performed, the switchback roller 32 continues normal rotation and the recording paper 16 is discharged. When image recording is also performed on the back surface of the recording paper 16, the switchback roller is used when the second end of the recording paper 16 reaches the stop position 90 between the first auxiliary roller 66 and the second auxiliary roller 67. The reversal of 32 is started, and the recording paper 16 is reliably sent to the second path 33 with the second end as the head. The stop position 90 is a position upstream of the second auxiliary roller 67 in the first direction of conveyance and in the vicinity of the second auxiliary roller 67.

[First Guide]

  A first guide 68 that is rotatable about the drive shaft 70 is provided on the upstream side of the second path 33 in the second conveyance direction. As shown in FIG. 3, the second path 33 extends obliquely downward from the branch port 48. The first guide 68 changes its posture between a first posture and a second posture. When the first guide 68 is in the first posture, the first guide 68 extends obliquely downward along the second path 33 from the drive shaft 70. A bearing portion 69 is provided at the base end of the first guide 68, and the bearing portion 69 is engaged with the switchback roller pair 43. Specifically, the bearing portion 69 is engaged with a drive shaft 70 (corresponding to a “support shaft” recited in the claims) of the switchback roller 32 and is rotatably supported by the drive shaft 70. ing. The first guide 68 is formed in a flat plate shape. Concavities and convexities are formed along the width direction at the center portion in the width direction of the tip 73 of the first guide 68. The first guide 68 extends in a direction perpendicular to the paper surface in FIG. 3 and reliably supports the recording paper 16 conveyed along the second path 33. Further, as shown in the figure, the first guide 68 extends from the position where the switchback roller 32 is disposed to the downstream side of the second path 33, and the upper surface 71 of the first guide 68 has a second path 33. A part of the wall surface (part of the wall surface on the lower side in the vertical direction) is formed. The posture in which the first guide 68 divides the second path 33 and guides the recording paper 16 along the second path 33 in this way is defined as the “first posture”.

  When the first guide 68 is in the second posture, it extends vertically downward from the drive shaft 70. The first guide 68 can be suspended by its own weight. Accordingly, the first guide 68 can release the second path 33 by rotating counterclockwise around the drive shaft 70 in FIG. 3 (see FIG. 6). The posture in which the first guide 68 releases the second path 33 in this way is defined as the “second posture”.

  In the present embodiment, when the first guide 68 is in the first posture, the tip 73 of the first guide 68 extends to a position upstream of the detection arm 50 of the second path 33. For this reason, when the first guide 68 is in the second posture, the upstream side of the detection arm 50 in the vertically lower wall surface of the second path 33 is opened. Specifically, as shown in FIG. 6, a predetermined gap is formed between the tip 73 of the first guide 68 and the wall surface 74 of the second path 33. The predetermined gap is a space different from the second path 33 formed on the lower side in the vertical direction, and the recording paper 16 can leave the second path 33 and pass through the contact with the detection arm 50. It is a gap. The wall surface 74 is formed by a member fixed to the housing 72. Concavities and convexities are formed along the width direction at positions corresponding to the concavities and convexities formed at the tip 73 in the central portion of the wall surface 74 in the width direction so as to alternate with the concavities and convexities formed at the tip 73. In addition, the front end side including the concavo-convex portion of the wall surface 74 is inclined toward the side away from the second path toward the upstream side in the second conveyance direction. Thereby, the sheet conveyed along the second direction of conveyance can be stably conveyed.

  In addition, the 1st guide 68 can open | release the 2nd path | pass 33 largely by rotating counterclockwise further from the 2nd attitude | position shown in FIG. Moreover, the 1st guide 68 comprises a part of wall surface which closes the 2nd path | pass 33 and divides the said 2nd path | pass 33 by rotating clockwise from the hanging state. In the present embodiment, the rotation of the first guide 68 is performed by inserting and removing the paper feed cassette 15. That is, when the paper feed cassette 15 is inserted into the printer unit 11, the upper end 81 of the paper feed cassette 15 presses the lower surface 82 of the first guide 68, and the second path 33 rotates clockwise. Note that the upper end 81 of the paper feed cassette 15 and the lower surface 82 of the first guide 68 are respectively provided on one end side in the width direction. When the paper feed cassette 15 is pulled out from this state, the first guide 68 is rotated by its own weight, and the second path 33 is released. At this time, the tip 73 of the first guide 68 has irregularities alternately formed with the irregularities of the wall surface 74, and is not supported by the wall surface 74, so when the paper feed cassette 15 is pulled out, the first guide 68. Changes its posture to the second posture.

  In the present embodiment, the first guide 68 rotates about the support shaft 53 by its own weight, but the first guide 68 may be biased to rotate counterclockwise about the drive shaft 70. Good. The specific structure of the urging means varies, but typically, a torsion coil spring is interposed between the rotating shaft 70 and the first guide 68. In this embodiment, the drive shaft 70 of the switchback roller 32 also serves as a support shaft that supports the first guide 68, but a support shaft that supports the first guide 68 is provided separately from the drive shaft 70. May be.

  FIG. 6 is a cross-sectional view of a main part of the multifunction machine 10 with the first guide 68 opened. As shown in the drawing, the paper feed cassette 15 is inserted inside the housing 72 and below the second path 33. The paper feed cassette 15 is mounted on a plurality of contact portions 75 (corresponding to “contact portions” recited in the claims) for supporting the bottom surface of the paper feed cassette 15 provided in the housing 72. Is done. The abutting portion 75 supports the paper feeding cassette 15 by abutting against the bottom surface of the paper feeding cassette 15 in a mounted state. A surface along the horizontal plane connecting the plurality of contact portions 75 is defined as a virtual plane 76 (corresponding to a “virtual plane” recited in the claims). The contact portion 75 is configured to contact a part of the bottom surface of the paper feed cassette 15, but may be configured to contact the entire bottom surface of the paper feed cassette 15. Although a plurality of contact portions 75 are provided, only one contact portion 75 may be provided.

  As shown in FIG. 3, when the first guide 68 is in the second posture, the recording paper 16 conveyed by the switchback roller pair 43 after the reverse rotation of the switchback roller 32 is started, the contact portion 75. The distance to reach the virtual plane 76 including is defined as the distance D2. Specifically, when the first guide 68 is in the second posture, the recording paper 16 whose second end is located at the stop position 90 is conveyed by the reverse rotation of the switchback roller 32 and reaches the virtual plane 76. Is the distance. When the first guide 68 is in the second posture, a part of the vertically lower wall surface of the second path 33 is opened, so that the recording paper 16 is conveyed toward the virtual plane 76 by its own weight. Further, as shown in FIG. 6, when the first guide 68 is in the first posture, the recording paper 16 conveyed by the switchback roller pair 43 after the reverse rotation of the switchback roller 32 is started in the second pass. The distance to reach the detection arm 50 along 33 is defined as the distance D1. Specifically, when the first guide 68 is in the first posture, the recording paper 16 whose second end is located at the stop position 90 is conveyed by the reverse rotation of the switchback roller 32, and along the second path 33. This is the distance to reach the detection arm 50. In this embodiment, the position of the detection arm 50, that is, the position of the rotation center axis 51 is determined so that the relationship D1 <D2 is established between the distance D1 and the distance D2.

  The multi-function device 10 according to the present embodiment is configured such that when the first guide 68 is in the first posture, the tip 73 of the first guide 68 is positioned upstream of the detection arm 50 in the second path. However, it is not limited to this. For example, when the first guide 68 is in the first posture, the tip 73 of the first guide 68 may be positioned downstream of the detection arm 50 in the second path. In that case, when the first guide 68 is in the second posture, the recording paper is located on the lower side in the vertical direction different from the second path 33 between the tip of the detection arm 50 and the upper surface 71 of the first guide 68. The position of the detection arm 50, that is, the position of the rotation center shaft 51 is determined so that a gap through which 16 can pass is formed. In other words, when the first guide 68 is in the second posture, the position where the gap through which the recording paper 16 can pass is formed between the tip of the detection arm 50 and the upper surface 71 of the first guide 68. The position of the detection arm 50 is determined as the most upstream side of the position of the detection arm 50 in the path 33. In other words, when the first guide 68 is in the second posture, the gap between the tip of the detection arm 50 and the upper surface 71 of the first guide 68 that allows the recording paper 16 to pass is formed. The position of the first arm 50 is determined so as to be downstream of the second path.

[Third guide]

  A third guide 100 that is rotatable about the shaft 27 of the paper feed roller 25 is provided on the downstream side of the second path 33 in the second conveyance direction. The third guide 100 is disposed downstream of the detection arm 50 in the second direction of the second path 33 in the transport direction. The third guide 100 is formed in a flat plate shape. The third guide 100 is rotatable about the shaft 27. When the paper feed cassette 15 is mounted, the third guide 100 constitutes a part of the wall surface defining the second path 33 as shown in FIG. Yes. In a state in which the paper feed cassette 15 is detached, the second path 33 can be opened by rotating counterclockwise about the shaft 27 as shown in FIG.

[Control unit]

  FIG. 7 is a block diagram illustrating a configuration of the control unit 90 of the multifunction machine 10. The control unit 90 controls the overall operation of the multifunction machine 10, but detailed description of the control of the scanner unit 12 and the recording unit 24 is omitted. The control unit 90 includes a CPU 91 that performs arithmetic processing, a ROM 92 that stores a control program, a RAM 93 that is used as a data storage area or a work area, and an EEPROM 94 that stores setting information and the like. It is configured as a microcomputer. Each component is connected via a bus 95 so that data can be transferred.

  A drive circuit 96 is connected to the bus 95. The drive circuit 96 drives the LF motor 85 and the ASF motor 86. The LF motor 85 is connected to the transport roller 35, the paper discharge roller 39, the switchback roller 32, and the like, and drives them. The ASF motor 86 drives the paper feed rollers 25 and 28. The drive circuit 96 includes a driver for driving the LF motor 85 and the ASF motor 86, and the LF motor 85 and the ASF motor 86 are independently controlled by these drivers. The driving force of the LF motor 85 is transmitted to the transport roller 35, the paper discharge roller 39, and the switchback roller 32 via a known drive transmission mechanism. The rotational force of the ASF motor 86 is also transmitted to the paper feed rollers 25 and 28 via the drive transmission mechanism described above.

  In the multifunction machine 10 according to the present embodiment, the LF motor 85 is a drive source for the transport roller 35 and the paper discharge roller 39. Accordingly, the recording paper 16 is transported toward the platen 36, and the recording paper 16 positioned on the platen 36 and the recorded recording paper 16 are transported in the first transport direction. Further, the LF motor 85 also serves as a drive source for normal and reverse rotation of the switchback roller 32. When an image is recorded on the back surface of the recording paper 16, the LF motor 85 is reversed by the switchback roller pair 43. To the second path 33. Specifically, the recorded recording paper 16 is transported in the first transport direction by the forward rotation of the switchback roller 32. Then, when the second end of the recording paper 16 reaches the stop position 90, the reverse rotation of the switchback roller 32 is started.

  The rotary encoder 97, the optical sensor 56, and the registration sensor 34 are connected to the bus 95. The rotary encoder 97 detects the amount of rotation of the switchback roller 32 driven by the LF motor 85 and is attached to the casing 72 of the printer unit 11. Based on the level of the output signal of the optical sensor 56 and the encoder amount detected by the rotary encoder 97, the control unit 90 determines whether or not the recording paper 16 is present in the transport path 31 and the second path 33 and the leading or trailing edge of the recording paper 16. The position and the conveyance amount of the recording paper 16 are grasped. Note that encoder amounts corresponding to the distances D1 and D2 are recorded in the EEPROM 94. Therefore, the CPU 91 can determine whether the transport amount of the recording paper 16 that is switched back and sent to the second pass 3 exceeds the distances D1 and D2.

[Inserting and unloading paper cassettes and transporting recording paper]

  As shown in FIGS. 2 and 3, the multifunction machine 10 is in a state in which the recording paper 16 can be fed to the conveyance path 31 when the paper feed cassette 15 holding the recording paper 16 is attached. At this time, the first guide 68 is displaced to the first posture, and the second path 33 is partitioned. When the LF motor 85 is driven and the switchback roller 32, the conveyance motor 35, and the paper discharge roller 39 are rotated forward, the recording paper 16 is conveyed in the first conveyance direction along the conveyance path 31 with the first end as the head. . The recording sheet 16 conveyed along the conveyance path 31 records an image on the first surface by the recording unit 17. When an image is also recorded on the second surface of the recording paper 16, the switchback roller 32 reverses and the recording paper 16 is sent to the second path 33 with the second end as the head. When the recording paper 16 enters the second path 33, the recording paper 16 comes into contact with the detection arm 50, and the detection arm 50 is pushed down by the recording paper 16 and falls down from the second path 33. Thus, the presence of the recording paper 16 is detected by the sheet detection mechanism 47, and it is determined that the recording paper 16 is normally conveyed along the second path 33. The recording paper 16 sent to the second path 33 is returned to the transport path 21 and the transport path 31 again starting from the second end, and an image is recorded on the second surface by the recording unit 17.

  When the paper feed cassette 15 is removed, the first guide 68 changes to the second posture as shown in FIG. That is, the first guide 68 is rotated downward in the vertical direction, and the wall surface on the lower side in the vertical direction that defines the second path 33 is rotated downward in the vertical direction to open the second path 33. Thus, when the first guide 68 changes its posture, the user can easily perform so-called jam processing when a jam occurs in the second pass 33.

  It is assumed that the paper feed cassette 15 is removed during the conveyance of the recording paper 16. In that case, the recording paper 16 sent to the second path 33 falls from the opened second path 33, and therefore jamming occurs. More specifically, the recording paper 16 passes through a gap between the tip 73 of the first guide 68 and the wall surface 74 of the second path 33 and falls downward in the vertical direction different from the second path 33. If the recording paper 16 continues to be fed by the switchback roller 32 in this state, the jammed state may deteriorate and the recording paper 16 may be damaged. However, in this embodiment, when the recording paper 16 moves outside the second path 33, the sheet detection mechanism 47 does not come into contact with the detection arm 50, so that the sheet detection mechanism 47 does not move even though the switchback roller 32 repeats reverse rotation. The recording paper 16 is not detected.

  Specifically, if the optical sensor 56 does not output an ON / OFF switching signal when the recording paper 16 is sent by the switchback roller 32 in the second direction of conveyance in the second direction, the recording paper 16 is in the second state. It can be determined that the vehicle has left the path 33. This is because the detection arm 50 is disposed at a position where the relationship of D1 <D2 is established with respect to the distances D1 and D2, and therefore, if the first guide 68 is in the second posture, the recording paper 16 is in the second path 33. This is because it is expected to have moved to the outside and reached the virtual plane 76. Note that the conveyance amount of the recording paper 16 is grasped by the encoder amount of the rotary encoder 97 (that is, corresponding to the rotation speed of the switchback roller 32) as described above.

  In such a case, the control unit 90 can stop the driving of the LF motor 85 based on the rotation speed of the switchback roller 32. If the conveyance is stopped when the recording paper 16 is sent by the distance D2, it is prevented that the jamming state of the recording paper 16 deteriorates and the recording paper 16 is damaged. In the present embodiment, the distances D1 and D2 are stored in advance, and the driving of the LF motor 85 is stopped based on the encoder amount corresponding to these distances. Therefore, the rotation control of the switchback roller 32 is very simple.

  Note that the rotation control of the switchback roller 32 can also be performed by the driving time of the LF motor 85. That is, the control unit 90 stops the LF motor 85 when the detection arm 50 does not detect the presence of the recording paper 16 even if a predetermined time has elapsed after the switchback roller 32 is reversed. This prevents the recording paper 16 jam condition from deteriorating. The fixed time in this case is a time until the transport distance of the recording paper 16 switched back exceeds the distance D1 and is expected to reach the distance D2. This time is set in advance and stored in the EEPROM 94.

  In the present embodiment, since the drive shaft 70 that supports the first guide 68 is disposed at the above-described position, the recording paper 16 must always be in the second pass when the first guide 68 is changed to the second posture. Leave from 33. Therefore, it is possible to prevent the jam from occurring in the second path 33 when the paper feed cassette 15 is removed, and to reliably prevent the jam from deteriorating.

  In addition, as described above, when the paper feeding cassette 15 is removed while the recording paper 16 is being conveyed, the recording paper 16 sent to the second path 33 moves to the outside of the second path 33. It should be. However, for example, the recording paper 16 may reach or come into contact with the detection arm 50 even though the second path 33 is opened due to the rigidity of the recording paper 16 (so-called waist strength). In this case, if the detection arm 50 is easily submerged from the second path 33, it is erroneously detected as normal conveyance even though the second path 33 is opened. Then, the recording paper 16 may move to the outside of the second path 33 after being normally detected by the sheet detection mechanism 47, and the jam state of the recording paper 16 will be deteriorated. However, in the present embodiment, since the detection arm 50 is biased so as to protrude with respect to the second path 33, such erroneous detection is suppressed. Further, in a state where the paper feed cassette 15 is removed, the downstream side of the second path 33 in the second conveyance direction is opened by the third guide 100. Therefore, even if the recording paper 16 reaches the detection arm 50, the recording paper 16 is jammed because the second path 33 is opened by the third guide 100. However, in the present embodiment, the detection arm 50 is urged so as to protrude with respect to the second path 33. Therefore, when the paper feed cassette 15 is removed, a jam can be detected at an early stage. It becomes possible.

  Further, in the present embodiment, since the second guide 44 and the detection arm 49 are provided, the recording paper 16 on which the image is recorded on the first surface is supported by the guide support surface 45 of the second guide 44. It is sent in the first direction of conveyance. When the recording paper 16 comes into contact with the detection arm 49, it is detected that the recording paper 16 is conveyed along the conveyance path 31. Therefore, the switchback timing of the recording paper 16 can be accurately controlled.

  Further, since the detection arms 49 and 50 are provided on the rotation center shaft 51, the detection arms 49 and 50 operate simultaneously when the rotation center shaft 51 rotates. Accordingly, the sheet detection mechanism 47 outputs a detection signal when the recording paper 16 is transported along the transport path 31 and along the second path 33. That is, since it is detected by the single optical sensor 56 that the recording paper 16 has been transported along both the transport path 31 and the second path 33, the structure of the sheet detection mechanism 47 is simplified.

DESCRIPTION OF SYMBOLS 10 ... Multifunction machine 11 ... Printer part 16 ... Recording paper 17 ... Recording part 21 ... Conveyance path 23 ... Conveyance path 31 ... Conveyance path 32 ... Switchback roller 33 ... Second pass 43 ... Switchback roller pair 44 ... Second guide 45 ... Guide support surface 46 ... Recess 47 ... Sheet detection mechanism 48 ... Branch port 49 ... Detection arm 50... Detection arm 51... Rotation center axis 52... Rotation wheel 56... Optical sensor 63 ... Flap 64 ... Shaft 67 ... Second auxiliary roller 68. -1st guide 70 ... Drive shaft 72 ... Case 73 ... Tip 74 ... Wall surface 75 ... Upper surface 76 ... Virtual plane 90 ... Control part

Claims (7)

A sheet cassette for holding sheets fed in the first direction of conveyance along the first path starting from the first end;
An image is recorded on the first surface of the sheet sent from the sheet cassette to the first pass, and the second end opposite to the first end is used as a head, and the second pass from the first pass again. A recording unit for recording an image on the second surface of the sheet returned to one pass;
The sheet is disposed downstream in the first conveyance direction from the branch port that leads from the first path to the second path, and conveys the sheet in the first direction in the conveyance direction or the second direction in the conveyance direction by rotating forward or reverse. A transport roller;
A conveyance detecting means that has a first arm capable of appearing and retracting in the second path, and detects the sheet when the first arm comes into contact with the sheet conveyed along the second path;
A first guide that extends obliquely downward from the branch port toward the downstream side of the second path and that is pivotable about a support shaft;
Even if the sheet on which the image is recorded on the first surface is conveyed at least a distance necessary to reach the first arm in the second direction of conveyance along the second path by the reverse rotation of the conveyance roller, the conveyance is performed. A controller that stops the transport roller when the detection means does not detect the sheet,
The first guide is
When the sheet cassette is mounted, a vertically lower wall surface defining the second path is formed, and a sheet conveyed in the second direction of conveyance by the conveyance roller is guided along the second path. A first posture;
When the sheet cassette is detached, the sheet cassette is pivoted vertically downward about the support shaft so that the sheet is detached from the second path and contact between the sheet and the first arm is avoided. An image recording apparatus that changes posture to a second posture that opens the upstream side of the first arm in the second path. The first arm is
A gap formed between the front end of the first arm and the wall surface when the first guide changes to the second posture, and the sheet can pass through vertically downward and the second guide The image recording apparatus according to claim 1, wherein the image recording apparatus is disposed on the downstream side of the second path from the position of the gap different from the path. It further includes a contact portion that is disposed vertically below the second path and contacts the bottom surface of the sheet cassette in a state where the sheet cassette is mounted.
The above sheet cassette
Mounted between the second path and the contact portion;
The first arm is
When the first guide is in the first posture, the sheet conveyed by the reverse rotation of the conveying roller reaches the first arm along the second path after the reverse rotation of the conveying roller is started. Let D1 be the distance until
When the first guide is in the second posture, the reverse rotation of the conveyance roller is started, and then the sheet conveyed by the reverse rotation of the conveyance roller is detached from the second path and the contact portion is moved. When the distance to reach the containing virtual plane is D2,
The image recording apparatus according to claim 1, wherein the image recording apparatus is disposed at a position where a relationship of D1 <D2 is established.   The image recording apparatus according to claim 2, further comprising an urging member that urges the first arm so as to protrude with respect to the second path. A guide provided downstream of the recording unit in the first direction of conveyance and supporting the second surface of the sheet on which the image is recorded on the first surface by the recording unit and guiding the sheet in the first direction of conveyance. A second guide having a support surface;
The transport detection means is
A second arm capable of appearing and retracting from the guide support surface with respect to the first path on the downstream side in the first conveyance direction from the recording portion of the first path;
A rotation center shaft having an outer peripheral surface, the first arm and the second arm projecting from the outer peripheral surface;
The sheet conveyed along the first path or the second path abuts on the first arm or the second arm, and the rotation center axis rotates to move along the first path or the second path. The image recording apparatus according to claim 1, wherein the image recording apparatus is configured to detect a conveyed sheet.   A third guide that rotates between a state in which the second path is defined by the sheet cassette being mounted and a state in which the second path is opened by the separation of the sheet cassette is provided. The image recording apparatus according to any one of 1 to 5.   The image recording apparatus according to claim 6, wherein the third guide is rotatably provided on the downstream side of the second path with respect to the first arm.

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