JP5621617B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an inkjet recording apparatus that records an image on a sheet, and more particularly, to an inkjet recording apparatus that can record an image on both sides of a sheet.

  Conventionally, an image recording apparatus capable of recording an image on both surfaces of a sheet such as a recording sheet is known (see Patent Document 1). In this type of image recording apparatus, a sheet fed from a paper feed tray is conveyed to a recording unit, and an image is recorded on the surface of the sheet by the recording unit. A branch port is provided downstream of the recording unit in the transport direction, and a reverse transport path is formed starting from the branch port. During double-sided recording, the sheet on which the image is recorded on the surface by the recording unit is switched back and conveyed by a switchback conveying roller provided downstream in the conveying direction from the branch port. The switched-back sheet is changed in the traveling direction to the reverse direction, branched from the branch port, and conveyed to the reverse conveyance path passing below the recording unit. The sheet is conveyed again to the recording unit through the reverse conveyance path. In the same manner as when an image is formed on the front surface of the sheet that has reached the recording unit, an image is recorded on the back surface by the recording unit. Thereafter, the sheet on which images are recorded on both sides is discharged to a discharge tray.

  A flap that is rotatably supported is provided on the upper side of the branch port. The flap is normally biased downward (branch port side) by its own weight or an elastic force such as a spring. When the sheet conveyed from the recording unit comes into contact with the flap, the flap is pushed up by the sheet and passes through the sheet. When the trailing edge of the sheet passes through the flap and reaches the branch port, the trailing edge of the sheet is pushed down by the downward biasing force of the flap. As a result, the rear end of the sheet is pressed against the guide surface of the reverse conveyance path, and the rear end of the sheet is directed to the reverse conveyance path.

  There is also known an image recording apparatus having a function of recording an image record on the surface of a thick paper or a label surface (label surface) of a disk medium such as a CD or DVD (see Patent Document 2). This type of image recording apparatus has a straight path formed linearly from a sheet discharge port for discharging a recorded sheet to an upstream side in the discharge direction of the recording unit. For example, when recording an image on the label surface of a disk medium, the disk tray is inserted from the discharge port toward the straight path, and the disk medium on the disk tray is set on the upstream side of the recording unit. At this time, in order to allow the disc tray to enter the upstream side of the recording unit, the rollers, the platen, and the like of the transport roller pair provided in the linear path are separated downward. This ensures a gap through which the disc tray can pass through the straight path.

  Patent Document 3 discloses an ink jet image forming apparatus in which a paper conveyance path connecting two print heads provided in a conveyance path is formed with a path length shorter than the length of the paper to be printed. .

JP 2010-208718 A JP 2010-76421 A JP 2001-341292 A

  By the way, in a conventional image recording apparatus capable of double-sided recording, a sheet during image recording is conveyed by a pair of conveyance rollers on the upstream side of the recording unit and a pair of paper discharge rollers on the downstream side of the recording unit. However, in the case of an ink jet recording apparatus, the ink attached to the recording surface is not dried immediately after image recording. For this reason, the upper roller (the roller that contacts the recording surface) of the pair of paper discharge rollers is formed in a spur shape to prevent ink adhesion, and the nip pressure (pressure contact force) with the opposing drive roller Is set to be extremely smaller than the upstream conveying roller pair. Therefore, when the recording paper whose rear end has passed the pair of transport rollers is transported only by the pair of paper discharge rollers, the drive roller slips, the recording paper skews, or in some cases the recording paper is in the transport path. There is a risk of clogging. In order to detect such a conveyance failure, in the image recording apparatus of Patent Document 1, a sheet sensor is provided between the discharge roller pair and the switchback conveyance roller so as to detect a sheet conveyance failure. .

  However, if a sheet sensor is provided between the pair of paper discharge rollers and the switchback conveying roller, not only the peripheral mechanism is complicated, but also the handling of the lead wires of the sensor becomes complicated and the assemblability deteriorates. Further, since a sheet sensor must be provided, the cost increases. In addition, a space for mounting the sheet sensor must be secured, which hinders downsizing of the apparatus.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a mechanism capable of reducing the number of parts and making the apparatus compact.

(1) The present invention provides a first conveyance path, a recording unit, a first conveyance roller pair, a second conveyance roller pair, a second conveyance path, a sheet sensor, a flap, and a third conveyance roller pair. The inkjet recording apparatus includes an interlocking mechanism and a rotary encoder.
The first conveyance path includes a curved curved path that guides the sheet in the first conveyance direction from a tray that accommodates the sheet, and a horizontal straight path that extends from the curved path to the sheet discharge port on the downstream side in the first conveyance direction. Have. The recording unit records an image on the sheet on the straight path. The first conveyance roller pair is provided upstream of the recording unit in the first conveyance direction, and conveys the sheet in the first conveyance path in the first conveyance direction. The second conveying roller pair is provided downstream of the recording unit in the first conveying direction, and includes a spur and a driving roller that further conveys the sheet in the first conveying direction. The second transport path is branched from the first transport path at a branch port provided downstream of the second transport roller pair in the first transport direction, and upstream of the first transport roller pair in the first transport direction. The sheet is extended so as to merge with the first conveyance path at the junction provided in the sheet, and guides the sheet from the branch port to the second conveyance direction toward the junction through the lower side of the recording unit. The sheet sensor is provided between the junction and the first conveyance roller pair in the first conveyance path, and detects the presence or absence of a sheet passing through the first conveyance path. The flap extends from a support shaft provided on the upstream side in the first conveyance direction from the branch port to the downstream side in the first conveyance direction, and has a first posture and at least an extension end positioned above the branch port. It is supported so as to be rotatable around the support shaft between the branch port and a second posture that enters the second transport path. The third conveying roller pair is provided on the downstream side in the first conveying direction from the branching port, conveys the sheet in the first conveying direction during single-sided recording, switches the sheet back to the double-sided recording unit, and then from the branching port. It conveys to the said 2nd conveyance direction through the said 2nd conveyance path. The interlocking mechanism transmits the driving force of the driving source to each of the first to third transport roller pairs to interlock the first to third transport roller pairs. The rotary encoder is provided in any one of the first conveyance roller pair, the second conveyance roller pair, the third conveyance roller pair, and the drive source, and the sheet in the first conveyance path and the second conveyance path. This is for measuring the transport amount. The first transport roller pair and the third transport roller pair have a first path length from a nip point of the first transport roller pair to a nip point of the third transport roller pair that can be fed from the tray. It is arranged to be shorter than the sheet length.

  In this configuration, no sensor is provided near the branch port. For this reason, since the sensor mounting space that has been secured in the past is reduced, the nip distance from the nip point of the first transport roller pair to the nip point of the third transport roller pair is shortened. Specifically, the first conveyance roller pair and the third conveyance roller pair are arranged so that the distance between the nips is shorter than the minimum sheet length that can be fed from the tray. Therefore, before the trailing edge of the sheet being conveyed by the first conveying roller pair leaves the nip point of the first conveying roller pair, the leading edge of the sheet reaches the nip point of the third conveying roller pair, and the third It is pinched by a pair of transport rollers. Therefore, in the section from the first conveying roller pair to the third conveying roller pair, the sheet is surely nipped and conveyed by both or either of the first conveying roller pair and the third conveying roller pair. Further, after the trailing edge of the sheet has passed through the first conveying roller pair, the sheet is conveyed by the second conveying roller pair and the third conveying roller pair. This prevents sheet clogging or conveyance failure between the first conveyance roller pair and the third conveyance roller pair.

(2) In the sheet sensor, the second path length from the sheet detectable position by the sheet sensor to the nip point of the third conveyance roller pair is shorter than the minimum sheet length that can be conveyed from the tray. Is arranged.

  If configured in this way, even if a malfunction occurs in the third pair of conveyance rollers and a conveyance failure such as slip occurs, the sheet sensor can detect the trailing edge of the sheet. Based on this, it can be determined whether the sheet is jammed or has a conveyance failure.

(3) The ink jet recording apparatus of the present invention further includes a support member that supports the lower guide member of the straight path so as to be movable between a third posture and a fourth posture spaced downward from the third posture. . The support member holds the lower guide member in the third posture during recording on the sheet fed from the tray, and is placed on a disc tray inserted into the straight path from the sheet discharge port. At the time of recording on the disc medium, the lower guide member is held in the fourth posture.

  When such a support member is employed, each component of the support member is concentrated in the vicinity of the branch port, so that a space for mounting a sensor for detecting a sheet in the vicinity of the branch port cannot be secured. For this reason, in the said structure, this invention which employ | adopts the structure which does not arrange | position a sensor near a branch port is suitable.

(4) The curved path is formed in an arc shape so that the direction when the sheet is conveyed on the straight path is reversed with respect to the direction when the sheet is fed from the tray. The present invention is suitable for such a configuration.

(5) The ink jet recording apparatus of the present invention includes an arm that is rotatable about a fulcrum defined between the tray and the second transport path, and a feed that is rotatably supported on the tip side of the arm. And a feeding mechanism that feeds the sheet from the tray to the first conveyance path by being rotated while being in contact with the sheet held on the tray. In this case, the first path length is equal to or shorter than the third path length from the contact point of the feeding roller to the sheet to the nip point of the first conveying roller pair.

  In the ink jet recording apparatus configured as described above, the length (sheet length) of the minimum size sheet that can be fed from the tray in the conveyance path direction is set to the third path length so that the first conveyance roller pair is nipped. The necessary amount will be added. In this case, if the first path length is equal to or shorter than the third path length, the minimum size sheet can be fed from the tray, and the minimum size sheet can be fed to the first conveying roller even on a straight path. It becomes possible to convey at least one of the pair or the third conveyance roller pair.

  According to the present invention, it is possible to reduce the number of parts in the portion from the straight road to the branch port, and to make the device compact.

FIG. 1 is a perspective view of a multifunction machine 10 as an example of an embodiment of the present invention. FIG. 2 is a longitudinal sectional view schematically showing the internal structure of the printer unit 11. FIG. 3 is a schematic diagram schematically showing the configuration of the cam drive mechanism 134. FIG. 4 is a block diagram for explaining the outline of the drive system of the transport motor 110. FIG. 5 is a schematic diagram for explaining the arrangement relationship of each pair of conveyance rollers.

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

[Outline of MFP 10]
As shown in FIG. 1, the multifunction machine 10 is generally formed in a thin rectangular parallelepiped, and a printer unit 11 of an ink jet recording system is provided at the lower part. The multifunction machine 10 has various functions such as a facsimile function and a print function. The presence or absence of functions other than the print function is arbitrary. Therefore, in this embodiment, descriptions of functions other than the print function and components that realize the functions are omitted.

[Configuration of Printer Unit 11]
As shown in FIG. 2, the printer unit 11 mainly includes a tray 20 (an example of the tray of the present invention) capable of holding recording papers of various sizes (an example of the sheet of the present invention), and a recording sheet from the tray 20. A feeding unit 15 (an example of the feeding mechanism of the present invention) that picks up and feeds, and an inkjet recording type recording unit 24 (an example of the recording unit of the present invention) that performs image recording using ink. ing.

  The printer unit 11 has a casing 14 (see FIG. 1) in which an opening 13 (see FIG. 1) is formed in the front, and the tray 20 is provided so as to be able to be inserted and removed from the opening 13 in the front-rear direction 8. That is, the tray 20 can be attached to and removed from the casing 14.

  A tray guide 51 is provided above the tray 20. The tray guide 51 is slidably supported by the casing 14, and is in a state of protruding from the front as shown in FIG. 1B from a state where it is housed inside as shown in FIG. It is possible to pull forward. A disk tray 53 (see FIG. 1B, an example of the disk tray of the present invention) is supported on the upper surface of the tray guide 51 so that it can be inserted and removed in the front-rear direction 8. The disk tray 53 is a flat plate member having a thickness of about 3 mm that can hold a disk medium such as a CD or a DVD. When the disc tray 53 is inserted into the tray guide 51 while the disc medium is held on the disc tray 53, the disc medium is set at a position where recording can be performed by the recording unit 20. In addition, when the tray guide 51 is pulled out, a cam drive mechanism 134, which will be described later, operates, and a straight path 65B (corresponding to the straight path of the present invention), which will be described later, is expanded downward. Thus, the disc tray 53 can be inserted into the straight path 65B.

  Control of the printer unit 11 is performed by the control unit 100 (see FIG. 4). The control unit 100 drives the printer unit 11 based on signals and data input from an external device, and records an image on a recording medium. In the present embodiment, the control unit 100 places the recording paper stored in the tray 20 on the recording unit 24 and records the image on the recording paper, and places the recording paper on the disc tray 53 inserted from the opening 13. A label recording mode for recording an image on the label surface of the disc medium, and performs recording control according to one of the recording modes.

[Feeding unit 15]
As shown in FIG. 2, the feeding unit 15 is provided above the tray 20 and below the recording unit 24. The feeding unit 15 includes a paper feeding roller 25 (an example of the feeding roller of the present invention), a paper feeding arm 26 (an example of the arm of the present invention), and a drive transmission mechanism 27 in which a plurality of gears are engaged. I have. A support shaft 28 is provided between the tray 20 and a reverse conveyance path 67 (an example of a second conveyance path of the present invention) described later. One end of the paper feed arm 26 is pivotally supported by a support shaft 28, and thus the paper feed arm 26 is rotatable about the support shaft 28 in the direction of an arrow 29. The paper feed arm 26 extends rearward and obliquely downward from the support shaft 28, and a paper feed roller 25 is rotatably supported at the tip of the paper feed arm 26. As a result, the paper feed roller 25 can come into contact with the recording paper placed on the tray 20 and can be separated from the tray 20. The paper feeding roller 25 is rotated by a driving force of a paper feeding motor (not shown) transmitted by the drive transmission mechanism 27. The paper feed roller 25 rotates while being in contact with the uppermost recording paper among the recording papers stacked on the tray 20, thereby removing the recording paper from the other recording paper on the lower side. It separates and it feeds to the below-mentioned curved path 65A (an example of the curved path of this invention).

[Conveyance path 65]
Inside the printer unit 11, a conveyance path 65 (an example of a first conveyance path according to the present invention) is formed from the front end (rear end) of the tray 20 to the discharge holding unit 79 via the recording unit 24. Yes. The conveyance path 65 is divided into a curved path 65 </ b> A formed between the leading end of the tray 20 and the recording unit 24, and a straight path 65 </ b> B formed between the recording unit 24 and the paper discharge holding unit 79.

  The curved path 65 </ b> A is a curved path extending from the vicinity of the upper end of the separation inclined plate 22 provided in the tray 20 to the recording unit 24. The curved path 65 </ b> A is generally formed in an arc shape centering on the inside of the printer unit 11. The recording paper fed from the tray 20 travels along the curved path 65A along the conveyance direction (the direction indicated by the one-dot chain line in FIG. 2) in the first conveyance direction (the direction of the arrow attached to the one-dot chain line in FIG. (Corresponding to the first transport direction of the invention) and is guided directly below the recording unit 24. That is, the curved path 65 </ b> A is curved so that the direction when the recording paper is conveyed directly below the recording unit 24 is reversed with respect to the direction when the recording paper is fed from the tray 20. The curved path 65A is defined by an outer guide member 18 and an inner guide member 19 that face each other with a predetermined interval. Note that the outer guide member 18 and the inner guide member 19 and guide members 83, 31, and 32, which will be described later, all extend in the direction perpendicular to the plane of FIG. 2 (the left-right direction 9 in FIG. 1).

  The straight path 65 </ b> B is a straight, generally horizontal path that extends from directly below the recording unit 24 to the discharge holding unit 79. This straight path 65B passes not only the recording paper from the tray 20, but also the disc tray 53 (see FIG. 1) inserted from the opening 13. The recording paper and the disc tray 53 are guided along the straight path 65B. The straight path 65B is formed by the recording unit 24 and the platen 42 facing each other with a predetermined interval at a location where the recording unit 24 is provided, and at a location where the recording unit 24 is not provided. The guide members are separated from each other with a gap therebetween.

  In the present embodiment, the spur 61, the platen 42, the second drive roller 62, the linear guide member 83, and the third drive roller 45 are arranged in that order in the first transport direction as members that bear the lower guide of the straight path 65B. Has been. These members are examples of the lower guide member of the present invention, and the lower guides of the straight path 65B are defined by these members. The linear guide member 83 is a plate-shaped resin member disposed between the second drive roller 62 and a branch port 36 described later. The linear guide member 83 has a recess 84. The recess 84 opens to the upper surface of the straight guide member 83, that is, the lower guide surface of the straight path 65B. The recess 84 is a groove extending along the front-rear direction 8. The recess 84 may be formed so as to extend downstream in the first transport direction and reach the downstream end of the linear guide member 83. In this case, the downstream side of the recess 84 communicates with the branch port 36. The size and position of the recess 84 are designed so that a first auxiliary roller 47 described later can be advanced and retracted into the recess 84. The recess 84 is not a single groove, but a plurality of grooves are provided side by side in the left-right direction 9 according to the number of the first auxiliary rollers 47, and is formed in a comb shape. The other members that bear the lower guide will be described later.

  Moreover, in this embodiment, the 1st drive roller 60, the recording part 24, the spur 63, the flap 49, and the spur 46 are arrange | positioned in the order in the 1st conveyance direction as a member which bears the upper side guide of the straight path 65B. The upper guides of the straight path 65B are defined by these members. The other members that bear the upper guide will be described later.

  A branch port 36 (an example of the branch port of the present invention) is provided in the straight path 65B. During double-sided image recording, the recording sheet conveyed along the straight path 65B is switched back downstream of the branch port 36 in the first conveyance direction, and conveyed toward a reverse conveyance path 67 described later.

[Recording unit 24]
The recording unit 24 performs image recording on the recording paper fed from the tray 20 or the disk medium on the disk tray 48 inserted in the straight path 65B by the ink jet recording method. The recording unit 24 is disposed above the tray 20. The recording unit 24 reciprocates in the left-right direction 9 (direction perpendicular to the paper surface in FIG. 2). A platen 42 for holding the recording paper horizontally is provided below the recording unit 24. In the process of reciprocating in the left-right direction 9, the recording unit 24 discharges ink supplied from an ink cartridge (not shown) from a nozzle 39 onto a recording sheet conveyed on the platen 42. As a result, an image is recorded on the recording paper in the conveyance path 65.

[Feed roller pair 59, discharge roller pair 64, switchback roller pair 44]
As shown in FIG. 2, the upstream side in the first conveyance direction from the recording unit 24, specifically, between the downstream end of the outer guide member 18 and the inner guide member 19 in the first conveyance direction and the recording unit 24. A feed roller pair 59 (an example of the first transport roller pair of the present invention) including a first drive roller 60 and a pinch roller 61 is provided. The pinch roller 61 is disposed below the first drive roller 60 and is pressed against the roller surface of the first drive roller 60 by an elastic member such as a spring (not shown). The pair of feed rollers 59 pinches the recording paper conveyed through the curved path 65A and feeds it onto the platen 42.

  As shown in FIG. 5, the feed roller pair 59 is disposed at a position P2 that is separated from the contact point P1 between the paper feed roller 25 and the recording paper by a predetermined distance along the conveyance path. More specifically, the nip point of the feed roller pair 59 is disposed so as to coincide with the position P2. No means for conveying the recording paper is provided between the paper feed roller 25 and the feed roller pair 59. For this reason, the recording paper that can be fed from the tray 20 in the printer 11 has a length in the transport path direction (length in the longitudinal direction) along the transport path from the position P1 to the position P2 (the present invention). In the third path length). In the present embodiment, the minimum size recording paper that can be fed from the tray 20 in the printer 11 is the photo L size (89 mm × 127 mm). In this case, the path length L1 is designed to be shorter than 127 mm so that the photo L size recording paper can be fed from the tray 20. If the holding allowance necessary for the feed roller pair 59 to hold the recording sheet is α, the path length L1 is designed to be (127−α) mm.

  As shown in FIG. 4, a rotary encoder 97 (an example of the rotary encoder of the present invention) is attached to the rotation shaft of the first drive roller 60. The rotary encoder 97 outputs a pulse signal in accordance with the rotational displacement amount of the shaft, and is an integral type in which an encoder disk and an optical sensor are incorporated. The control unit 100 can detect the rotation amount of the first drive roller 60 by counting the number of pulses of the pulse signal from the rotary encoder 97, and calculates the conveyance amount of the recording paper based on the rotation amount. For example, the control unit 100 determines the transport position of the recording paper in each of the transport paths 65 and 67 based on the transport amount after the leading edge of the recording paper is detected by the detection mechanism 72 described later and the path length from the rotor 74. Can be determined accurately. In the present embodiment, the rotary encoder 97 is attached to the rotation shaft of the first drive roller 60, but it may be attached to the second drive roller 62 or the third drive roller 45, or the conveyance motor 110. (Refer to FIG. 4).

  A downstream side of the recording unit 24 in the first conveyance direction, specifically, between the recording unit 24 and the linear guide member 83, a discharge roller pair 64 including a second driving roller 62 and a spur 63 (second conveyance of the present invention). An example of a roller pair) is provided. A spur 63 is provided above the second drive roller 62. The spur 63 is pressed against the roller surface of the second drive roller 62 by an elastic member such as a spring (not shown). The discharge roller pair 64 sandwiches the recording sheet on which the image is recorded by the recording unit 24 and further conveys the recording sheet to the downstream side in the first conveying direction. Therefore, the pressure contact force (nip force) of the discharge roller pair 64 is set to be extremely smaller than the pressure contact force of the feed roller pair 59.

  Each of the driving rollers 60 and 62 is rotated by a rotational driving force transmitted from the conveying motor 110 (see FIG. 4) via the driving transmission mechanism 112 (an example of the interlocking mechanism of the present invention). The drive transmission mechanism 112 is composed of a planetary gear or the like, and the rotational driving force of the transport motor 110 is applied to any of the drive rollers 60 and 62 regardless of whether the transport motor 110 is rotated in the forward rotation direction or the reverse rotation direction. Also, the drive rollers 60 and 62 are rotated in one rotation direction. Thereby, the recording sheet is conveyed in the first conveying direction.

  A switchback roller pair 44 composed of a third drive roller 45 and a spur 46 on the downstream side of the branch port 36 in the first conveyance direction (an example of the third conveyance roller pair of the present invention, hereinafter referred to as “SB roller pair 44”). .) Is provided. The spur 46 is disposed above the third drive roller 45 and is pressed against the roller surface of the third drive roller 45 by an elastic member such as a spring (not shown).

  As shown in FIG. 5, the SB roller pair 44 is disposed at a position P3 that is separated from the position P2 of the feed roller pair 59 along the conveyance path by a predetermined distance. Specifically, the nip point of the SB roller pair 44 is arranged so as to coincide with the position P3. Between the feed roller pair 59 and the SB roller pair 44, a discharge roller pair 64 is provided as means for transporting the recording paper. However, the pressure contact force of the discharge roller pair 64 is extremely small. Therefore, in the present embodiment, the SB roller pair 44 is disposed at a position P3 where only the feed roller pair 59 can reach the leading edge of the photographic L size recording paper to the SB roller pair 44. Specifically, the path length L2 along the transport path from the position P2 to the position P3 (corresponding to the first path length of the present invention) is the length (127 mm) in the transport path direction of the photographic L size recording paper. The SB conveyance roller pair 44 is disposed so as to be shorter than the above. In the present embodiment, the path length L2 is designed to be the same as or shorter than the path length L1 (= 127−α). In the case of the roller arrangement configuration of the conventional apparatus, the optical sensor, the rotor, and the like are provided in the section from the discharge roller pair 64 to the SB roller pair 44. Although it could not be shorter than the length in the path direction (127 mm), in this embodiment, since the optical sensor and the rotor in the section are not provided, the arrangement position of the SB roller pair is fed by the amount of the mounting space. It became possible to pack the roller pair 59 side.

  The third driving roller 45 is driven to rotate in the forward or reverse direction by receiving a rotational driving force in the forward or reverse rotational direction from the conveying motor 100 via the drive transmission mechanism 112. For example, when single-sided recording is performed, the third drive roller 45 is rotated in the forward rotation direction. As a result, the recording sheet is nipped by the SB roller pair 44 and discharged from the downstream discharge port 78 (an example of the sheet discharge port of the present invention) to the discharge holding unit 79. On the other hand, when double-sided recording is performed, the rotation direction of the third drive roller 45 is switched from the normal rotation direction to the reverse rotation direction with the SB roller pair 44 sandwiching the trailing edge of the recording paper. When the rotation direction of the third drive roller 45 is switched to the reverse rotation direction after the trailing edge of the recording sheet is directed to the reverse conveyance path 67 described later by the path switching unit 41 described below, the recording sheet is transferred to the reverse conveyance path. It is conveyed toward 67.

[Detection mechanism 72]
The upstream side of the feed roller pair 59 in the first conveyance direction, specifically, the junction 37 (an example of the junction port of the present invention) on the upstream side of the feed roller pair 59 in the first conveyance direction and the feed roller pair 59. Is provided with a detection mechanism 72 (an example of the sheet sensor of the present invention). The detection mechanism 72 detects the presence or absence of a recording sheet in the conveyance path 65 conveyed toward the recording unit 20, and detects the leading edge position and the trailing edge position of the recording sheet in the conveyance path 65. As shown in FIG. 2, the detection mechanism 72 includes a transmissive optical sensor 73 including a light emitting element and a light receiving element, and an arm-shaped rotor 74 that protrudes so as to cross the conveyance path 65. The rotor 74 is supported so as to be swingable about the rotation shaft 75, and is held by a torsion coil spring or the like in a posture crossing the conveyance path 65 when no recording sheet is present in the conveyance path 65. The rotor 74 is provided with a detector 76 that advances and retreats to the detection unit of the optical sensor 73. When the recording paper is conveyed to the conveyance path 65 and the rotor 74 rotates, the detector 76 moves out of the detection unit, and when the recording paper passes through the rotor 74, the detector 76 enters the detection unit again. Based on the change in the signal from the optical sensor 73 at this time, the control unit 100 detects the position of the recording sheet in the conveyance path 65.

[Route switching unit 41]
As shown in FIG. 2, the path switching unit 41 is disposed downstream of the discharge roller pair 64 in the first transport direction and upstream of the SB roller pair 44 in the first transport direction. The path switching unit 41 includes a first auxiliary roller 47, a second auxiliary roller 48, a flap 49 (an example of the flap of the present invention), and a support shaft 87.

  A support shaft 87 extending in the direction perpendicular to the plane of FIG. 2 (left and right direction 9 in FIG. 1) is provided on the frame of the printer unit 11 and the like. The flap 49 extends substantially downstream from the support shaft 87 in the first conveying direction, and is rotatably supported by the support shaft 87. A first auxiliary roller 47 and a second auxiliary roller 48 are pivotally supported on the flap 49. Since the roller surfaces of the auxiliary rollers 47 and 48 are in contact with the recording surface of the recording paper, they are formed in a spur shape like the spur 63 and the spur 46. The first auxiliary roller 47 is provided on the base end side (rear side) of the flap 49, and the second auxiliary roller 48 is provided on the extension end side (front side) of the flap 49.

  The flap 49 is configured to be able to change its posture, and a discharge posture (a posture shown by a broken line in FIG. 2, which corresponds to the first posture of the present invention) positioned above the straight guide member 83 and the branch port 36, and The second auxiliary roller 48 on the extended end side rotates between a reverse posture (a posture shown by a solid line in FIG. 2, which corresponds to the second posture of the present invention) entering below the branch port 36. When the external force is not applied to the flap 49, the extension end side hangs down by its own weight. Therefore, the flap 49 always maintains the inverted posture. When the flap 49 is in the reverse posture, the first auxiliary roller 47 enters the recess 84. On the other hand, when the flap 49 is in the discharging posture, the first auxiliary roller 47 is retracted from the recess 84. Note that the flap 49 may be elastically biased so as to be reversed by an elastic member such as a spring.

[Reverse conveying path 67]
As shown in FIG. 2, a reverse conveyance path 67 is formed between the recording unit 24 and the tray 20. The reverse conveyance path 67 is branched from the straight path 65 </ b> B at the branch port 36, passes through the lower side of the recording unit 24 and the upper side of the paper feed arm 27, and the upstream junction in the first conveyance direction with respect to the feed roller pair 59. 37 joins the curved path 65A. The recording sheet is conveyed in the second conveyance direction along the reverse conveyance path 67. Here, the second transport direction refers to a direction indicated by a two-dot chain line with an arrow in FIG. 2 in a direction from the branch port 36 toward the merging direction 37 through the reverse transport path 67.

  The upper side of the reverse conveyance path 67 is partitioned by the second guide member 32 formed in a generally thin flat plate rectangular shape. In addition, the lower side of the reverse conveyance path 67 is partitioned by a first guide member 31 formed in a generally thin flat plate rectangular shape. Specifically, the reverse conveyance path 67 is defined by the lower surface of the second guide member 32 and the upper surface of the first guide member 31. That is, the second guide member 32 and the first guide member 31 are arranged to face each other with a predetermined interval through which the recording paper can pass. Both ends of the second guide member 32 and the first guide member 31 are supported by the frame of the printer unit 11 and the like.

[Conveying roller pair 70]
As shown in FIG. 2, the reverse conveyance path 67 is provided with a conveyance roller pair 70 including a fourth drive roller 68 and a driven roller 69. The driven roller 69 is disposed below the recording unit 24 and above the fourth drive roller 68. The fourth drive roller 68 is pressed against the roller surface of the driven roller 69 by a coil spring (not shown). The fourth driving roller 68 is driven to rotate in the forward rotation direction or the reverse rotation direction by receiving a driving force in the forward / reverse rotation direction from the conveying motor 110. In the present embodiment, the conveyance roller pair 70 has a reverse conveyance path by sandwiching a recording sheet between the fourth drive roller 68 and the driven roller 69 when the conveyance motor is rotated in the reverse direction. The recording sheet conveyed to 67 is conveyed in the second conveyance direction.

[Cam drive mechanism 134]
As shown in FIG. 3, the printer unit 11 is provided with a cam drive mechanism 134 (an example of a support member of the present invention). The cam drive mechanism 134 is a member of the spur 61, the platen 42, the second drive roller 62, the linear guide member 83, and the third drive roller 45 (hereinafter referred to as “lower guide member”) that bears the lower guide of the straight path 65B. 3) (the posture shown by a solid line in FIG. 2, the posture shown in FIG. 3A) and the fourth posture (the posture shown by a wavy line in FIG. 2) spaced downward from the third posture, FIG. (B) posture). In the present embodiment, when the lower guide member is in the fourth posture, the straight path 65B is expanded to a width capable of transporting the disc tray 53 inserted along the insertion direction 98 from the opening 13.

  The cam drive mechanism 124 has a link plate 136 connected to the tray guide 51 (see FIG. 1). Two link plates 136 are provided so as to form a pair in the left-right direction 9 with a space therebetween. A spur 61, a platen 42, a second drive roller 62, a linear guide member 83, and a third drive roller 45 are arranged between the link plates 136, and both end portions in the left-right direction 9 of each of the lower guide members are linked. It is supported by a groove-like slide cam 137 formed on the plate 136. 3 shows a slide cam 137A for supporting the spur 61, a slide cam 137B for supporting the second drive roller 62, and a slide cam 137C for supporting the third drive roller 45. 42 and the slide cam which supports the linear guide member 83 are omitted. Since it is configured in this way, when the tray guide 51 is pulled forward in the third posture shown in FIG. 3A, the link plate 136 is moved forward (right side in FIG. 3). Thereby, the support position of the supported portion of each lower guide member moves from the upper position to the lower position of the slide cam, and the lower guide member assumes the fourth posture (see FIG. 3B). As a result, the straight path 65B is expanded downward. Needless to say, the straight path 65 </ b> B may be expanded using a mechanism other than the cam drive mechanism 124.

[Operations and effects of the embodiment]
As described above, in this embodiment, the path length L2 along the transport path from the position P2 to the position P3 is shorter than the length (127 mm) in the transport path direction of the recording sheet of the L size photo. The feed roller pair 59 and the SB roller pair 44 are disposed. Therefore, the leading edge of the recording paper reaches the nip point of the SB roller pair 44 before the trailing edge of the minimum size recording paper conveyed by the feed roller pair 59 leaves the nip point of the feed roller pair 59. It is clamped by the SB roller pair 44. As a result, in the section from the feed roller pair 59 to the SB roller pair 44, the recording paper is reliably nipped and conveyed by both or one of the feed roller pair 59 and the SB roller pair 44. In addition, after the trailing edge of the recording sheet passes through the feed roller pair 59, the recording sheet is conveyed by both the discharge roller pair 64 and the SB roller pair 44. It is reliably transported in the first transport direction. This prevents the recording paper from being jammed or poorly conveyed between the feed roller pair 59 and the SB roller pair 44.

[Modification]
In the above-described embodiment, a configuration is described in which the feed roller pair 59 and the SB roller pair 44 are arranged so that the path length L2 is shorter than the length (127 mm) in the conveyance path direction of the recording sheet of L size photographic paper. However, the path length L3 (corresponding to the second path length of the present invention) along the transport path from the rotor 74 to the SB roller pair 44 is the length in the transport path direction of the recording sheet of the photographic L size size (127 mm). May be shorter. In other words, the path length L3 from the detection position of the recording paper (that is, the position where the rotor 74 is provided) by the detection mechanism 74 to the SB roller pair 44 is the length (127 mm) in the conveyance path direction of the L-size recording paper. The detection mechanism 74 and the rotor 74 may be arranged at a position shorter than (). If configured in this way, even if a malfunction occurs in the SB roller pair 44 and a conveyance failure such as slip occurs, the detection mechanism 72 is in a position where it can detect the trailing edge of the minimum size recording sheet. Based on the detection time or the like by the detection mechanism 72, the control unit 100 can reliably determine that a recording paper jam or conveyance failure has occurred.

10: MFP 11: printer unit 15: feeding unit 20: tray 24: recording unit 25: paper feed roller 26: paper feed arm 44: switchback roller pair 45: third drive roller 49: flap 53: disc tray 59 : Feed roller pair 60: first drive roller 62: second drive roller 64: discharge roller pair 65: transport path 67: reverse transport path 112: drive transmission mechanism 134: cam drive mechanism

Claims (5)

A first conveying path having a curved curved path that guides the sheet from the tray that accommodates the sheet in the first conveying direction, and a horizontal straight path extending from the curved path to the downstream sheet discharge port in the first conveying direction; ,
A recording unit for recording an image on a sheet in the straight path;
A first conveying roller pair provided upstream from the recording unit in the first conveying direction and conveying the sheet in the first conveying path in the first conveying direction;
A second conveying roller pair provided on the downstream side in the first conveying direction from the recording unit, and further comprising a spur and a driving roller for conveying the sheet further in the first conveying direction;
A branch port provided on the downstream side in the first conveyance direction from the second conveyance roller pair is branched from the first conveyance path, and a junction port provided on the upstream side in the first conveyance direction from the first conveyance roller pair. A second conveyance path that guides the sheet from the branch port to the second conveyance direction toward the merge port through the lower side of the recording unit;
A sheet sensor that is provided between the junction and the first conveying roller pair in the first conveying path and detects the presence or absence of a sheet passing through the first conveying path;
A first posture located at the upper side of the branch port and at least an extended end are extended from a support shaft provided upstream from the branch port toward the first transport direction toward the first transport direction. A flap supported so as to be rotatable about the support shaft between a second posture entering the second transport path from the second posture,
Provided downstream from the branch port in the first conveyance direction, conveys the sheet in the first conveyance direction during single-sided recording, switches back the sheet to the double-sided recording unit, and passes through the second conveyance path from the branch port. A third transport roller pair transported in the second transport direction;
An interlocking mechanism for transmitting a driving force of a driving source to each of the first to third transport roller pairs to interlock the first to third transport roller pairs;
Measures the sheet conveyance amount in the first conveyance path and the second conveyance path provided in any of the first conveyance roller pair, the second conveyance roller pair, the third conveyance roller pair, and the drive source. A rotary encoder for
The first transport roller pair and the third transport roller pair have a first path length along the first transport path from the nip point of the first transport roller pair to the nip point of the third transport roller pair. Inkjet recording apparatus arranged so as to be shorter than the minimum sheet length that can be fed from. The sheet sensor is configured such that the second path length along the first transport path from the sheet detectable position by the sheet sensor to the nip point of the third transport roller pair is the minimum sheet length that can be fed from the tray. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is arranged to be shorter. A support member for supporting the lower guide member of the straight path so as to be movable between a third posture and a fourth posture spaced downward from the third posture;
The support member holds the lower guide member in the third posture during recording on the sheet fed from the tray, and is placed on a disc tray inserted into the straight path from the sheet discharge port. The inkjet recording apparatus according to claim 1 or 2, wherein the lower guide member is held in the fourth posture during recording on the disc medium.   The curved path is formed in an arc shape so that a direction when the sheet is conveyed on the straight path is reversed with respect to a direction when the sheet is fed from the tray. An ink jet recording apparatus according to any one of the above. An arm rotatable around a fulcrum defined between the tray and the second transport path, and a feed roller rotatably supported on the tip side of the arm, the feed roller comprising: A feeding mechanism that feeds the sheet from the tray to the first conveyance path by being rotated in contact with the sheet held on the tray;
The first path length is equal to or shorter than a third path length along the first path from a contact point of the feeding roller to the sheet to a nip point of the first conveying roller pair. 4. The ink jet recording apparatus according to any one of 4 above.

Images