JP5906646B2 - Transport device - Google Patents

Description

  The present invention relates to a transport apparatus capable of transporting a recording medium along a transport path.

  Many conveyance devices that convey a recording medium along a conveyance path include a plurality of roller pairs. The recording medium is conveyed by being sandwiched between these roller pairs. The two rollers constituting each roller pair are in contact with each other with a strong force in order to secure a force for conveying the recording medium.

  In a state where the recording medium is sandwiched between a plurality of roller pairs, when the recording medium is transported in the transport direction, the rear end of the recording medium is placed on the roller pair disposed on the most downstream side in the transport direction. There is a moment to escape. At the moment when the trailing edge of the recording medium passes through the roller pair, the force applied by the roller pair that has been applied to the trailing edge of the recording medium is not suddenly applied to the trailing edge of the recording medium. Here, the force by the roller pair is a force for maintaining the rear end of the recording medium in the nipping position by the roller pair. When the force by the roller pair is suddenly stopped, a force in the conveying direction acts on the recording medium. As a result, a phenomenon occurs in which the recording medium is transported in the transport direction more than originally assumed at the moment.

  In order to prevent the above phenomenon from occurring, in the recording apparatus disclosed in Patent Document 1, the rear end of the recording medium sandwiched between the driven roller (pinch roller 5) and the driving roller (conveying roller 4) is Before leaving the sandwiched position, the driven roller is moved upward to be separated from the driving roller.

Japanese Patent Laid-Open No. 10-26851

  However, the recording apparatus disclosed in Patent Document 1 may cause the following problems. As described above, the driving roller and the driven roller are in contact with each other with a strong force. Therefore, at the moment when the driven roller is moved upward, the pressing force that has been applied from the driven roller until then is not applied to the drive roller.

  Here, both ends of the driving roller are supported by bearings, but a gap is provided between the outer diameter of the driving roller and the inner diameter of the bearing in order to easily rotate the driving roller. For this reason, there is a possibility that the position of the driving roller that is no longer subjected to the pressing force is shifted by the gap.

  The positional deviation of the driving roller is accompanied by the positional deviation of the recording medium in contact with the driving roller. As a result, an error occurs between the movement amount of the recording medium detected by the encoder or the like from the rotation amount of the driving roller and the actual movement amount of the recording medium.

  Further, when the rotational force of the driving roller is transmitted to other rollers provided in the conveyance path by connection via a belt or gear, the positional deviation of the driving roller is affected by the belt or gear. There is a risk of transmission to other rollers. Specifically, when the position of the driving roller is shifted, the position of the belt is shifted or the gear rotates. This causes the other roller to rotate. As a result, the recording medium is slightly conveyed at the position where it contacts the other roller.

  The present invention has been made in view of the above problems, and an object of the present invention is to maintain the pressure contact force against the drive roller even if the pressure contact force of the driven roller pressed against the drive roller is weakened. An object of the present invention is to provide a transport apparatus that can prevent the positional deviation of the first position.

  (1) A conveying device of the present invention is provided in a conveying path for guiding a recording medium, a driving roller that is provided with a driving force from a driving source and rotates, and is opposed to the driving roller. A driven roller that sandwiches a recording medium with the driving roller and conveys the recording medium along the conveying path, and an urging member that urges the driven roller against the driving roller, An adjustment mechanism that adjusts an urging force of the driven roller against the driving roller by the urging member; and an abutting mechanism having an abutting member that can abut against the driving roller. The contact mechanism presses the contact member against the drive roller when the biasing force of the driven roller to the drive roller by the biasing member is weakened by the adjustment mechanism.

  The driven roller urges the drive roller by an urging member. If the biasing force of the driven roller against the driving roller is weakened by the adjustment mechanism, the position of the driving roller may be shifted. However, according to this structure, even if the urging | biasing force with respect to a drive roller is weakened, a contact mechanism presses a contact member to a drive roller. That is, the driving roller is biased from the contact member instead of being biased from the driven roller.

  (2) The driven roller can be changed in posture between a first posture in contact with the driving roller and a second posture separated from the driving roller, and the adjustment mechanism biases the driven roller in the urging state. The biasing force is adjusted by changing the posture from the first posture to the second posture against the biasing force of the member.

  According to this configuration, the urging force can be weakened only by separating the driven roller from the drive roller.

  (3) In the contact mechanism, the contact member is passed through the shaft of the drive roller, extends in the same direction as the shaft of the driven roller, and has a first position that contacts the adjustment mechanism, and A rotary shaft that can be moved to a second position spaced apart from the adjustment mechanism, and is provided on the rotary shaft, and has a first circumferential surface having a first distance from the rotary shaft to the circumferential surface, and a circumference from the rotary shaft. A rotating cam having a second peripheral surface having a diameter up to the surface longer than the first distance, and the second peripheral surface contacting and separating from the contact member by rotation of the rotating shaft. The rotating shaft moves to the first position when the second peripheral surface comes into contact with the contact member, contacts the adjustment mechanism, and the second peripheral surface moves away from the contact member. To move to the second position and move away from the adjustment mechanism. The adjustment mechanism abuts on the rotation shaft to change the posture of the driven roller from the first posture to the second posture against the urging force of the urging member, and from the rotation shaft. By being separated, the driven roller is changed in posture from the second posture to the first posture by the urging force of the urging member.

  According to this configuration, the driven roller can be separated from the drive roller while maintaining the state where the drive roller is biased.

  Further, according to this configuration, when the driven roller is separated from the driving roller against the biasing force of the biasing member, the biasing force of the biasing member is applied to the driven roller, the adjustment mechanism, the rotating shaft, and the contact. It is transmitted to the drive roller via the member. That is, according to this configuration, the urging member can be used in order to realize the pressing to the driving roller by the contact member.

  (4) The adjustment mechanism adjusts the urging force of the driven roller against the drive roller by the urging member after the contact mechanism presses the contact member against the drive roller.

  According to this configuration, the driven roller can be separated from the drive roller while maintaining the state where the drive roller is biased.

  (5) The adjustment mechanism adjusts the urging force of the driven roller to the drive roller by the urging member on the condition that the rotation of the drive roller is stopped. The contact mechanism presses the contact member against the drive roller on the condition that the rotation of the drive roller is stopped.

  If at least one of the driven roller or the contact member moves while the drive roller is rotating, the position of the recording medium in contact with the drive roller may be shifted. According to this configuration, the adjustment of the urging force that may be accompanied by the movement of the driven roller and the contact member and the pressing of the contact member against the drive roller are executed when the rotation of the drive roller is stopped. The positional deviation of the recording medium as described above can be prevented.

  (6) The transport device of the present invention rotates integrally with the drive roller, and includes a rotating body provided with a plurality of detection portions along a circumferential direction concentric with the rotation center, and the rotation target. The rotation amount of the drive roller is calculated based on the first detection unit that is provided at a position that can face the detection unit and detects the detection unit, and the number of detections of the detection unit by the first detection unit. And a calculating unit.

  When the position of the drive roller is deviated, the amount of movement of the recording medium calculated by the control unit that controls the operation of the apparatus based on the amount of rotation of the driving roller calculated by the calculation unit, and the actual movement of the recording medium There will be an error between the quantity. However, according to the configurations (1) to (5), it is possible to prevent the displacement of the driving roller. Therefore, it is possible to prevent the movement amount from being generated.

  (7) The conveying device of the present invention is provided with a first roller provided at a position different from the driving roller and the driven roller in the conveying path, and opposed to the first roller. A recording medium is sandwiched between the second roller and the second roller that can be transported along the transport path, and is connected to the driving roller and the first roller, and the rotational force of the driving roller is coupled to the first roller. And a drive transmission mechanism for transmitting to the roller.

  If the position of the drive roller is shifted, the position of the first roller connected to the drive roller via the drive transmission mechanism may be shifted. If the position of the first roller is deviated, the position of the recording medium that is nipped and conveyed by the first roller and the second roller may be shifted. However, according to the configurations (1) to (6), it is possible to prevent the displacement of the driving roller. Therefore, it is possible to prevent the displacement of the recording medium being nipped and conveyed by the first roller and the second roller.

  (8) The transport device according to the present invention is configured to detect that the rear end of the recording medium in the transport direction is transported to a predetermined position upstream of the nip position of the drive roller and the driven roller in the transport direction. A section. The adjustment mechanism weakens the urging force of the driven roller against the drive roller by the urging member based on the detection result of the second detection unit.

  As a result, the phenomenon described above, that is, the nip force is not applied to the recording medium nipped by the driving roller and the driven roller, whereby a force in the conveying direction acts on the recording medium, and the recording medium is It is possible to avoid a phenomenon that the sheet is transported in the transport direction more than the assumed amount. In addition, as described in the above (1), the drive roller is biased from the abutting member instead of being biased from the driven roller, so that it is possible to prevent displacement of the drive roller. In other words, according to this configuration, the above phenomenon can be avoided without causing the displacement of the driving roller.

  (9) The contact member can change its posture to a third posture in contact with the drive roller and a fourth posture separated from the drive roller. The contact mechanism changes the posture of the contact member from the fourth posture to the third posture when the biasing force of the driven roller to the drive roller by the biasing member is weakened by the adjustment mechanism. Thus, the contact member is pressed against the driving roller.

  According to this configuration, the pressing of the contact member against the drive roller can be realized only by bringing the contact member separated from the drive roller into contact with the drive roller.

  (10) The contact direction of the contact member with the drive roller is the same as the contact direction of the driven roller with respect to the drive roller.

  According to this configuration, the contact member and the driven roller are in contact with the drive roller from the same direction, so that the possibility that the position of the drive roller is shifted can be reduced.

  According to the present invention, even if the pressure contact force of the driven roller pressed against the drive roller is weakened, the drive roller is pressed by the contact member. Thereby, since the press-contact force with respect to a drive roller is maintained, position shift of a drive roller can be prevented.

FIG. 1A shows an external perspective view of the multifunction machine 10, and FIG. 1B shows a plan view around the first transport roller 60 and the second transport roller 62 in the printer 11. Yes. FIG. 2 is a longitudinal sectional view schematically showing the internal structure of the printer unit 11. FIG. 3 is a rear view schematically showing the first conveying roller 60, the pinch roller 61, the contact mechanism 90, and the convex portion 162. FIG. 3A shows a state where the pinch roller 61 is in the first posture. (B) shows a state in which the pinch roller 61 is in the second posture. FIG. 4 is a view for explaining the operation of the planet gear 157. FIG. 4A is a left side view schematically showing the planet gear 157 and the sun gear 155 when the pinch roller 61 is in the first posture. FIG. 4B is a left side view schematically showing the planet gear 157 and the sun gear 155 when the pinch roller 61 is in the second posture. FIG. 5 is a view for explaining the operation of the contact mechanism 90, and FIG. 5A shows a cross-sectional view taken along line AA of FIG. 1B when the pinch roller 61 is in the first posture. 1B is a cross-sectional view taken along the line BB in FIG. 1B when the pinch roller 61 is in the first posture, and FIG. 1C is a diagram when FIG. 1 is the case where the pinch roller 61 is in the second posture. An AA sectional view of (B) is shown, and (D) shows a BB sectional view of FIG. 1 (B) when the pinch roller 61 is in the second posture. FIG. 6 is a perspective view of the vicinity of the first conveyance roller 60 and the second conveyance roller 62 in the printer 11 as viewed obliquely from the upper front right. FIG. 7 is a perspective view of the vicinity of the first conveyance roller 60 and the second conveyance roller 62 in the printer 11 as viewed obliquely from the upper left front. FIG. 6 is a perspective view of the vicinity of the first conveyance roller 60 and the second conveyance roller 62 in the printer 11 as viewed obliquely from the upper front right. FIG. 9 is a characteristic diagram showing the pressure contact force to the first conveying roller 60 with respect to the diameter of the eccentric cam 160 on the contact member 161 side. FIG. 10 is a block diagram showing the configuration of the microcomputer 130.

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

[Multifunction machine 10]
As shown in FIG. 1, the multifunction machine 10 is formed in a generally thin rectangular parallelepiped, and records an image on a recording paper 12 (an example of a recording medium of the present invention, see FIG. 2) using an inkjet recording method at the bottom. A printer unit 11 is provided. The multifunction machine 10 has various functions such as a facsimile function and a print function. The multifunction machine 10 has a conveyance path 65 to be described later, and can convey the recording paper 12. That is, the multifunction machine 10 is an example of a transport apparatus according to the present invention.

  In the present embodiment, the multifunction machine 10 has only a single-sided image recording function, but may have a double-sided image recording function. The recording method in the printer unit 11 is not limited to the ink jet recording method, and may be an electrophotographic method, for example.

  The printer unit 11 has a housing 14 having an opening 13 formed in the front. In addition, a paper feed tray 20 and a paper discharge tray 21 (see FIG. 2) on which recording paper 12 of various sizes can be placed can be inserted and removed in the front-rear direction 8 from the opening 13.

  As shown in FIG. 2, the printer unit 11 is provided above the paper feed tray 20 and the paper feed unit 15 that picks up and feeds the recording paper 12 from the paper feed tray 20. An ink jet recording type recording unit 24 that discharges ink droplets onto the fed recording sheet 12 to record an image on the recording sheet 12, a first conveyance roller 60, a second conveyance roller 62, and the like are provided.

[Paper Feeder 15]
As shown in FIG. 2, the paper feed unit 15 is provided above the paper feed tray 20 and below the recording unit 24. The paper feed unit 15 includes a feed roller 25, a paper feed arm 26, and a drive transmission mechanism 27. The feed roller 25 is pivotally supported at the tip of the paper feed arm 26. The paper feed arm 26 rotates in the direction of an arrow 29 about a shaft 28 provided at the base end. As a result, the feed roller 25 can be brought into contact with and separated from the paper feed tray 20. That is, the feeding roller 25 can contact the recording paper 12 placed on the paper feed tray 20.

  The feeding roller 25 is rotated by the driving force of the paper feeding motor 70 (see FIG. 10) being transmitted. The feeding roller 25 separates the recording sheet 12 from the other recording sheets 12 while being in contact with the uppermost recording sheet 12 among the recording sheets 12 stacked on the sheet feeding tray 20. It sends out to the curved path 65A described below.

[Conveyance path 65]
As shown in FIG. 2, inside the printer unit 11, there is a conveyance path 65 (conveyance path of the present invention) from the front end (rear end) of the paper feed tray 20 to the paper discharge tray 21 through the recording unit 24. Example) is formed. The conveyance path 65 includes a curved path 65A formed between the leading end of the paper feed tray 20 and the first conveyance roller 60, and a discharge path 65B formed between the first conveyance roller 60 and the discharge tray 21. It is divided into and.

  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 paper feed 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 12 fed from the paper feed tray 20 by the feed roller 25 is attached along the curved path 65A along the conveyance direction (the direction indicated by the one-dot chain line in FIG. 2) in the conveyance direction (the one-dot chain line in FIG. 2). And is guided to the nipping position of the recording paper 12 by the first conveying roller 60 (an example of the driving roller of the present invention) and the pinch roller 61 (an example of the driven roller of the present invention). 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.

  The paper discharge path 65 </ b> B is a linear path that extends from the position where the recording paper 12 is held by the first transport roller 60 and the pinch roller 61 to the paper discharge tray 21. The recording paper 12 is guided along the paper discharge path 65B in the conveying direction. The paper discharge path 65B is defined by a platen 42 that is a plate-like member capable of supporting the recording unit 24 and the recording paper 12 that are opposed to each other at a predetermined interval at a location where the recording unit 24 is provided. In addition, the paper discharge path 65B is partitioned by an upper guide member 82 and a lower guide member 83 that face each other at a predetermined interval at a location where the recording unit 24 is not provided.

[Recording unit 24]
As shown in FIG. 2, the recording unit 24 is provided on the downstream side in the transport direction with respect to the first transport roller 60 in the paper discharge path 65B. The recording unit 24 is provided on the upper side of the paper discharge path 65B. The recording unit 24 includes a carriage 40 that is mounted with a recording head 38 and can reciprocate in the left-right direction 9.

  Ink is supplied to the recording head 38 from an ink cartridge (not shown). The recording head 38 ejects ink from the nozzle 39 as fine ink droplets. When the carriage 40 reciprocates in the left-right direction 9, ink droplets are ejected from the nozzles 39 to the recording paper 12 supported on the platen 42. As a result, an image is recorded on the recording paper 12.

[Conveying rollers 60, 62]
As shown in FIG. 2, the first conveyance roller 60 and the pinch roller 61 are provided in the conveyance path 65 on the upstream side in the conveyance direction with respect to the recording unit 24. The pinch roller 61 is disposed below the first conveyance roller 60 so as to face the first conveyance roller 60. The pinch roller 61 is biased by a coil spring 91 (an example of a biasing member of the present invention) shown in FIGS. 5A and 5C and FIGS. Is pressed against the roller surface. In other words, the coil spring 91 biases the pinch roller 61 toward the first transport roller 60. The lower end of the coil spring 91 is supported by the frame 43 (see FIGS. 5A and 5C) of the multifunction machine 10, and the upper end is attached to the holder 36 (see FIGS. 6 to 8) that supports the pinch roller 61. It has been. The first conveying roller 60 and the pinch roller 61 pinch the recording paper 12 that has been conveyed along the curved path 65A by the feeding roller 25 and convey it in the conveying direction along the paper discharge path 65B. As a result, the recording paper 12 is sent onto the platen 42.

  The pinch roller 61 is moved in the vertical direction 7 by a contact mechanism 90 described later. As a result, the pinch roller 61 is separated from the first posture in contact with the first transport roller 60 (see an example of the first posture of the present invention, FIG. 3A), and downward from the first transport roller 60. The posture changes to the second posture (an example of the second posture of the present invention, see FIG. 3B). The posture change of the pinch roller 61 by the contact mechanism 90 will be described later.

  A second conveyance roller 62 (an example of the first roller of the present invention) and a spur 63 (an example of the second roller of the present invention) are provided on the discharge path 65B on the downstream side of the recording unit 24 in the conveyance direction. Yes. The spur 63 is disposed above the second conveyance roller 62 so as to face the second conveyance roller 62. The spur 63 is pressed against the roller surface of the second conveying roller 62 by an elastic member such as a spring (not shown). The second conveyance roller 62 and the spur 63 pinch the recording paper 12 on which an image is recorded by the recording unit 24 and convey it along the paper discharge path 65B to the downstream side in the conveyance direction.

[Belt mechanism 120]
As shown in FIG. 7, the printer unit 11 is provided with a belt mechanism 120 (an example of a drive transmission mechanism of the present invention). The belt mechanism 120 includes a first gear 118, a second gear 119, a first pulley 121, a second pulley 122, and a belt 123. The belt mechanism 120 is connected to the first transport roller 60 and the second transport roller 62 as described below.

  The first gear 118 is attached to the shaft 34 of the first transport roller 60 on the left side of the paper discharge path 65B. The second gear 119 is attached to the shaft of the transport motor 71 on the left side of the paper discharge path 65B. The second gear 119 is provided to face the first gear 118 and meshes with the first gear 118. As a result, the first transport roller 60 receives the rotational driving force from the transport motor 71 (an example of the drive source of the present invention) via the second gear 119 and the first gear 118 that are part of the belt mechanism 120. To be rotated.

  The first pulley 121 is mounted on the left side of the transport path 65 adjacent to the second gear 119 on the shaft of the transport motor 71, that is, the shaft on which the second gear 119 is mounted. A belt 123, which will be described later, is laid along the peripheral surface of the first pulley 121. The first pulley 121 is driven by the conveyance motor 71 to rotate.

  The second pulley 122 is attached to the shaft 56 of the second transport roller 62 on the left side of the transport path 65. The second pulley 122 rotates integrally with the second transport roller 62 around the shaft 56. A belt 123, which will be described later, is laid along the peripheral surface of the second pulley 122.

  The belt 123 has an endless annular shape and is stretched around the first pulley 121 and the second pulley 122. One of the belts 123 is wound around the peripheral surface of the first pulley 121 and the other is wound around the peripheral surface of the second pulley 122. The belt 123 moves circumferentially when the first pulley 121 rotates. The second pulley 122 rotates as the belt 123 moves circumferentially. Thereby, the rotational driving force of the first pulley 121 is transmitted to the second pulley 122 via the belt 123. The belt 123 is given tension by a tensioner 126. As described above, the second transport roller 62 rotates from the transport motor 71 through the first pulley 121, the belt 123, and the second pulley 122, which are part of the belt mechanism 120, in the same manner as the first transport roller 60. The driving force, that is, the rotational force of the first conveying roller 60 is transmitted and rotated.

[Abutting mechanism 90]
The printer unit 11 is provided with a contact mechanism 90 (an example of a contact mechanism of the present invention). 3 and 6 to 8, the contact mechanism 90 includes a planet gear 156 having a shaft 157 extending in the left-right direction 9 which is the same direction as the shaft 35 of the pinch roller 61, and the planet gear 156. An eccentric cam 160 (an example of the rotating cam of the present invention) provided on the shaft 157 (an example of the rotating shaft of the present invention), and a shaft 34 (the present invention) at a position facing the eccentric cam 160 on the upper side. And an abutting member 161 (an example of the abutting member of the present invention) that can abut against the eccentric cam 160.

  As shown in FIGS. 3, 5 </ b> B, and 5 </ b> D, the eccentric cam 160 is a disk whose diameter periodically changes from the shaft 157. Specifically, the eccentric cam 160 has a first peripheral surface 92 (the first peripheral surface of the present invention) whose diameter from the shaft 157 to the peripheral surface of the planet gear 156 is the first distance R1 (an example of the first distance of the present invention). And a second peripheral surface 93 (an example of the second peripheral surface of the present invention) having a second distance R2 whose diameter from the shaft 157 to the peripheral surface of the planet gear 156 is longer than the first distance R1. ing. Further, as will be described later, the eccentric cam 160 is brought into contact with and separated from the lower surface 164 of the contact member 161 by the rotation of the shaft 157 of the planet gear 156.

  As shown in FIGS. 3 and 5, the abutting member 161 is a member having a lower surface 164 formed in a plane composed of a front-rear direction 8 and a left-right direction 9. An opening is provided near the upper surface of the contact member 161. A shaft 34 that is a part of the first conveying roller 60 is inserted into the opening. Thereby, the inner surface of the opening of the contact member 161 can contact the shaft 34 of the first conveying roller 60. That is, the contact member 161 can contact the first transport roller 60.

  As shown in FIGS. 3, 5 (A), (C), and FIGS. 6 to 8, the printer unit 11 protrudes from the shaft 35 of the pinch roller 61 toward the shaft 157 of the planet gear 156. The convex part 162 (an example of the adjusting mechanism of the present invention) is disposed. The convex part 162 adjusts the urging force of the pinch roller 61 against the first conveying roller 60 by the coil spring 91. In the present embodiment, the convex portion 162 adjusts the biasing force by changing the posture of the pinch roller 61 from the first posture to the second posture against the biasing force of the coil spring 91, as will be described later. Here, the pinch roller 61 in the first posture is shown in FIG. 3 (A), and the pinch roller 61 in the second posture is shown in FIG. 3 (B).

  As shown in FIG. 3, a plurality of pinch rollers 61 are provided along the shaft 35 at a predetermined interval. The convex portion 162 is formed at a position where the pinch roller 61 is not provided on the shaft 35. Further, as shown in FIGS. 3, 5 </ b> A, 5 </ b> C, and FIGS. 6 to 8, the convex portion 162 is formed with a hole 163 along the left-right direction 9. The shaft 157 of the planet gear 156 is inserted through the hole 163.

  As shown in FIGS. 3, 6, and 8, the planetary gear 156 in the contact mechanism 90 receives the driving force of the contact mechanism drive motor 72 from the first intermediate gear 51 to the seventh intermediate gear 57 and the transmission. Is transmitted via the unit 58.

  As shown in FIGS. 3 and 4, the shaft 157 of the planet gear 156 is inserted through a long hole 159 formed in a fixing plate 158 disposed on the right side of the sun gear 155. Thereby, the shaft 157 of the planet gear 156 can slide along the long hole 159. As will be described later, the shaft 157 of the planet gear 156 slides along the long hole 159 to be in contact with the bottom surface of the hole 163 formed in the convex portion 162 (the first position of the present invention). 3B and 5C), and a second position spaced from the convex portion 162 (an example of the second position of the present invention, see FIGS. 3A and 5A). It is movable. The long hole 159 has an arc shape so that the planet gear 153 can maintain meshing with the sun gear 155 even when the shaft 157 of the planet gear 156 slides along the long hole 159.

  As described above, the sun gear 155 is rotated by the rotation of the seventh intermediate gear 57 due to the rotation of the contact mechanism drive motor 72. The planet gear 156 is rotated by the rotation of the sun gear 155.

[Adjustment of Energizing Force to First Conveying Roller 60]
Hereinafter, adjustment of the urging force of the pinch roller 61 with respect to the first conveyance roller 60 by the convex portion 162 and the contact and separation between the eccentric cam 160 and the contact member 161 will be described in detail.

  First, the operation in the case of changing from the state shown in FIG. 3A to the state shown in FIG. 3B will be described. In the state shown in FIG. 3A, the pinch roller 61 and the first transport roller 60 are in contact with each other. That is, the pinch roller 61 is in the first posture. In the state shown in FIG. 3A, the shaft 157 of the planet gear 156 inserted through the hole 163 formed in the convex portion 162 is not in contact with the hole 163 (see FIG. 5A). ). That is, the shaft 157 of the planet gear 156 is located at the second position. Further, in the state shown in FIG. 3A, the second peripheral surface 93 (the diameter is the second distance R2) of the eccentric cam 160 is located below the shaft 157 of the planet gear 156, The first peripheral surface 92 (the diameter is the first distance R1) of the eccentric cam 160 is positioned above the shaft 157 of the planet gear 156 (see FIG. 5B). Thereby, the second peripheral surface 93 of the eccentric cam 160 is separated from the lower surface 164 of the contact member 161 located above the shaft 157 of the planet gear 156. Further, in the state shown in FIG. 3A, as shown in FIG. 9A, the pinch roller 61 presses the first conveying roller 60 with a predetermined pressing force, whereas The pressing force of the contact member 161 to the first transport roller 60 is zero.

  In the state shown in FIG. 3A, when the planet gear 156 is rotated by the drive transmission from the contact mechanism drive motor 72, the eccentric cam 160 is rotated. As the eccentric cam 160 is rotated, the diameter of the eccentric cam 160 on the contact member 161 side becomes longer from the first distance R1, and the peripheral surface of the eccentric cam 160 and the lower surface 164 of the contact member 161 contact each other (FIG. 9). (A) A point). When the eccentric cam 160 is further rotated, the peripheral surface of the eccentric cam 160 pushes the lower surface 164 of the contact member 161 from the lower side. Thereby, the contact member 161 pushed by the eccentric cam 160 pushes the first drive roller 60 from below. As a result, as shown by a broken line in FIG. 9A, the pressure contact force of the contact member 161 to the first conveying roller 60 increases.

  Here, both ends of the shaft 45 of the first transport roller 60 are rotatably supported by the frame 44 (see FIGS. 6 to 8) of the multifunction machine 10, except for the backlash with the frame 44. It is not movable. Therefore, a repulsive force from the contact member 161 inserted through the shaft 34 of the first conveying roller 60 acts on the eccentric cam 160. Thereby, the shaft 157 of the planet gear 156 provided with the eccentric cam 160 moves downward. Thereby, as shown in FIG. 5C, the shaft 157 of the planet gear 156 contacts the bottom surface of the hole 163 formed in the convex portion 162 (point B in FIG. 9A). That is, the shaft 157 of the planet gear 156 moves from the second position to the first position. The shaft 157 of the planet gear 156 pushes the convex portion 162 downward by the further rotation of the eccentric cam 160.

  The convex portion 162 is brought into contact with the shaft 157 of the planet gear 156 moved to the first position from the upper side and is pressed downward. Thereby, the convex part 162 and the pinch roller 61 integrated with the convex part 162 and the shaft 35 are moved downward against the urging force of the coil spring 91. As a result, as shown by the solid line in FIG. 9A, the pressure contact force of the pinch roller 61 to the first conveying roller 60 decreases. When the pinch roller 61 is completely separated from the first conveying roller 60, the pressure contact force becomes zero (point C in FIG. 9A). That is, the convex portion 162 is brought into contact with the shaft 157 of the planet gear 156, whereby the pinch roller 61 is moved from the first posture (see FIG. 3A) in contact with the first conveying roller 60 to the first position. The posture is changed to the second posture (see FIG. 3B) that is separated from the one transport roller 60.

  In the present embodiment, thereafter, the eccentric cam 160 continues to rotate until the diameter of the eccentric cam 160 on the contact member 161 side reaches the second distance R2.

  In this embodiment, the complete separation of the pinch roller 61 from the first conveying roller 60 (point C in FIG. 9A) indicates that the diameter of the rotating eccentric cam 160 on the contact member 161 side is the second distance. Although it was before reaching R2, as shown in FIG. 9B, the separation may be simultaneous with the arrival.

  In this embodiment, the maximum pressure contact force of the contact member 161 to the first transport roller 60 is the same as the maximum pressure contact force of the pinch roller 61 to the first transport roller 60. However, as shown in FIG. 9C, the maximum pressure contact force of the contact member 161 to the first transport roller 60 may be larger than the maximum pressure contact force of the pinch roller 61 to the first transport roller 60. . Further, the maximum pressure contact force of the contact member 161 to the first transport roller 60 may be smaller than the maximum pressure contact force of the pinch roller 61 to the first transport roller 60.

  In the operation described above, the convex portion 162 weakens the urging force of the pinch roller 61 against the first transport roller 60 by the coil spring 91 by separating the pinch roller 61 from the first transport roller 60. At this time, the second peripheral surface 93 of the eccentric cam 160 presses the contact member 161 upward. The contact member 161 pressed upward presses the shaft 34 of the first transport roller 60 inserted through the opening of the contact member 161 upward. That is, the contact mechanism 90 presses the contact member 161 against the first transport roller 60 when the urging force of the pinch roller 61 against the first transport roller 60 by the coil spring 91 is weakened by the convex portion 162.

  As described above, the contact member 161 presses the first transport roller 60 from the lower side. On the other hand, as described above, the pinch roller 61 is in contact with the first conveying roller 60 from below. That is, the contact direction of the contact member 161 with respect to the first transport roller 60 is the same as the contact direction of the pinch roller 61 with respect to the first transport roller 60.

  In the operation described above, the contact member 161 pressed by the eccentric cam 160 presses the first transport roller 60. The shaft 157 of the planet gear 156 moves downward by the repulsive force from the contact member 161 at this time. As a result of the convex portion 162 being pushed downward by the shaft 157 moved downward, the pinch roller 61 integrated with the convex portion 162 is separated from the first transport roller 60. That is, the convex portion 162 adjusts the urging force of the pinch roller 61 against the first transport roller 60 by the coil spring 91 after the contact mechanism 90 presses the contact member 161 against the first transport roller 60.

  Next, an operation in the case of changing from the state shown in FIG. 3B to the state shown in FIG. In the state shown in FIG. 3B, the pinch roller 61 and the first conveying roller 60 are separated from each other. That is, the pinch roller 61 is in the second posture. In the state shown in FIG. 3B, the shaft 157 of the planet gear 156 inserted through the hole 163 formed in the convex portion 162 is in contact with the bottom surface of the hole 163. That is, the shaft 157 of the planet gear 156 is located at the first position. Further, in the state shown in FIG. 3B, the second peripheral surface 93 (the diameter is the second distance R2) of the eccentric cam 160 is located above the shaft 157 of the planet gear 156, and the eccentric cam 160 is eccentric. The first peripheral surface 92 (the diameter is the first distance R1) of the cam 160 is located below the shaft 157 of the planet gear 156 (see FIG. 5D). As a result, the second peripheral surface 93 of the eccentric cam 160 is in contact with the lower surface 164 of the contact member 161 located above the shaft 157 of the planet gear 156.

  In the state shown in FIG. 3B, when the planet gear 156 is rotated by the drive transmission from the contact mechanism drive motor 72, the eccentric cam 160 is rotated. As the eccentric cam 160 is rotated, the diameter of the eccentric cam 160 on the contact member 161 side is shortened from the second distance R2, and the circumferential surface of the eccentric cam 160 and the lower surface 164 of the contact member 161 are separated (FIG. 5). (See (B)). Thereby, the repulsive force from the contact member 161 to the eccentric cam 160 does not act. As a result, the shaft 157 of the planet gear 156 provided with the eccentric cam 160 moves upward. For this reason, the shaft 157 of the planet gear 156 is separated from the bottom surface of the hole 163 formed in the convex portion 162 (see FIG. 5A). That is, the shaft 157 of the planet gear 156 moves from the first position to the second position.

  The convex portion 162 that is no longer pushed downward by the shaft 157 of the planet gear 156 is moved upward by the urging force of the coil spring 91. In other words, the convex portion 162 is separated from the shaft 157 of the planet gear 156, whereby the pinch roller 61 is moved from the second posture (see FIG. 3B) separated from the first conveyance roller 60 to the first conveyance. The posture is changed to the first posture (see FIG. 3A) in contact with the roller 60.

[Rotary encoder 73]
As shown in FIG. 1B and FIGS. 6 to 8, the multi function device 10 includes a rotary encoder 73. The rotary encoder 73 is attached to the shaft 34 of the first transport roller 60, and an encoder disk 74 (an example of the rotating body of the present invention) that rotates integrally with the shaft 34, and an optical sensor 75 (of the detecting unit of the present invention). Example). The encoder disk 74 has a pattern in which a plurality of transmission parts that transmit light at regular intervals and non-transmission parts that do not transmit light are alternately arranged at equal intervals in a circumferential direction concentric with the rotation center (not shown). An example of the detected part of the present invention) is provided. The optical sensor 75 is provided at a position on the encoder disk 74 that can face the position where the pattern is formed. In other words, the optical sensor 75 is provided at a position that can face the pattern by the rotation of the encoder disk 74. When the encoder disk 74 rotates with the shaft 34 of the first conveying roller 60, the pattern arranged on the encoder disk 74 is detected by the optical sensor 75. Each time the detection is performed, a pulse signal is generated by the optical sensor 75. That is, the pulse signal is generated based on the number of times the optical sensor 75 detects the pattern. The generated pulse signal is output from the optical sensor 75 to a microcomputer 130 (see FIG. 10) described later.

[Sheet Detection Unit 140]
As shown in FIG. 2, the printer unit 11 includes a sheet detection unit 140 that detects the leading edge and the trailing edge of the recording paper 12 that is fed from the paper feed tray 20 and conveyed along the curved path 65 </ b> A in the conveyance direction. . The sheet detector 140 is provided on the upstream side of the first conveying roller 60 in the curved path 65A.

  The sheet detector 140 includes, for example, a photo interrupter having a rotating member 141 having detectors 141A and 141B, a light emitting element (for example, a light emitting diode), and a light receiving element (for example, a phototransistor) that receives light emitted from the light emitting element. And the like optical sensor 142. The rotating member 141 is provided to be rotatable about a shaft 143. The detector 141A protrudes from the shaft 143 to the curved path 65A. When the leading end of the recording paper 12 being conveyed comes into contact with the rotating member 141 and pushes the rotating member 141, the detector 141B of the rotating member 141 is removed from the optical path between the light emitting element and the light receiving element. Therefore, light passes through the optical path. On the other hand, when the conveyed recording paper 12 passes through the rotating member 141, the rotating member 141 returns to the state shown in FIG. At this time, the detector 141B of the rotating member 141 enters the optical path and blocks light passing through the optical path.

  The optical sensor 142 outputs an analog electrical signal (voltage signal or current signal, an example of the detection signal of the present invention) corresponding to the intensity of light received by the light receiving element to a microcomputer 130 (see FIG. 10) described later.

[Microcomputer 130]
As shown in FIG. 10, the microcomputer 130 controls the overall operation of the multifunction machine 10. The microcomputer 130 includes a CPU 131, ROM 132, RAM 133, EEPROM 134, and ASIC 135. These are connected by an internal bus 137.

  The ROM 132 stores a program for the CPU 131 to control various operations. The RAM 133 is used as a storage area for temporarily recording data and signals used when the CPU 131 executes the program, or as a work area for data processing. The EEPROM 134 stores settings, flags, and the like that should be retained even after the power is turned off.

  Connected to the ASIC 135 are a paper feed motor 70, a transport motor 71, and a contact mechanism drive motor 72. When a drive signal for rotating each motor is input from the CPU 131 to a drive circuit corresponding to a predetermined motor, a drive current corresponding to the drive signal is output from the drive circuit to the corresponding motor, thereby corresponding The motor rotates forward or reverse at a predetermined rotational speed.

  Here, the microcomputer 130 does not output the drive current to the contact mechanism drive motor 72 in a state where the drive current is output to the transport motor 71. In other words, the microcomputer 130 outputs a drive current to the contact mechanism drive motor 72 in a state where the drive current is not output to the transport motor 71. Thereby, when the 1st conveyance roller 60 is rotating, the contact mechanism 90 does not operate | move. Further, the biasing force of the coil spring 91 is not adjusted when the first transport roller 60 is rotating. As described above, the convex portion 162 adjusts the urging force of the pinch roller 61 against the first conveyance roller 60 by the coil spring 91 on the condition that the rotation of the first conveyance roller 60 is stopped. Further, the contact mechanism 90 presses the contact member 161 against the first transport roller 60 on condition that the rotation of the first transport roller 60 is stopped.

  In the present embodiment, each motor 70, 71, 72 is an independent motor, but all or a part of each motor 70, 71, 72 may be shared. In that case, the drive transmission from the shared motor can be switched by a known drive transmission mechanism including a planetary gear or the like.

  The ASIC 135 receives a pulse signal output from the optical sensor 142 of the rotary encoder 73. The microcomputer 130 calculates the amount of rotation of the first transport roller 60 based on the pulse signal from the optical sensor 142. That is, the microcomputer 130 is an example of the calculation unit of the present invention.

  Further, the optical sensor 142 of the sheet detection unit 140 is connected to the ASIC 135. For example, when light passes through the optical path, that is, when the recording paper 12 presses the rotating member 141, the optical sensor 142 outputs a high level signal to the microcomputer 130. When the optical path is blocked by the rotating member 141, that is, when the recording paper 12 is not pushing the rotating member 141, the optical sensor 142 outputs a low level signal to the microcomputer 130. The microcomputer 130 detects the leading edge of the conveyed recording paper 12 based on the signal input from the optical sensor 142.

  The microcomputer 130 outputs a drive current to the contact mechanism drive motor 72 on condition that the rear end of the recording paper 12 in the conveyance direction is conveyed to a predetermined position 76 (an example of the predetermined position of the present invention). . As a result, the contact mechanism 90 is activated, and the urging force of the pinch roller 61 against the first conveying roller 60 by the coil spring 91 is weakened. That is, the microcomputer 130 causes the convex portion 162 to weaken the urging force of the pinch roller 61 against the first conveying roller 60 by the coil spring 91 based on the detection result of the sheet detection unit 140.

  Here, the predetermined position 76 is a position where the rear end of the recording paper 12 in the conveyance direction is the holding position of the recording paper 12 by the first conveyance roller 60 and the pinch roller 61, that is, a position upstream of the nip position in the conveyance direction. As a specific example, the predetermined position 76 is a position where the sheet detection unit 140 is disposed on the curved path 65A (see FIG. 2).

  For example, when the predetermined position 76 is the position of the specific example, the microcomputer 130 detects the timing when the input from the optical sensor 142 is switched from the high level to the low level. The timing is a timing at which the recording paper 12 switches from a state where the rotating member 141 is pressed (high level) to a state where the recording paper 12 does not press the rotating member 141 (low level). That is, the timing is the timing at which the trailing edge of the recording paper 12 passes through the sheet detection unit 140. When the microcomputer 130 detects the above timing, it outputs a drive current to the contact mechanism drive motor 72.

As described above, the microcomputer 130 and the sheet detection unit 140 are examples of the medium position detection unit of the present invention.

[Effect of the embodiment]
In the present embodiment, the pinch roller 61 biases the first transport roller 60 by the coil spring 91. If the urging force of the pinch roller 61 against the first conveyance roller 60 is weakened by the convex portion 162, the position of the first conveyance roller 60 may be shifted. However, according to the present embodiment, the contact mechanism 90 presses the contact member 161 against the first transport roller 60 even if the biasing force on the first transport roller 60 is weakened. That is, the first conveying roller 60 is urged from the contact member 161 instead of being urged from the pinch roller 61. Thereby, since the press-contact force with respect to the 1st conveyance roller 60 is maintained, the position shift of the 1st conveyance roller 60 can be prevented.

  Further, according to the present embodiment, the urging force can be weakened only by separating the pinch roller 61 from the first conveying roller 60.

  Further, according to the present embodiment, the pinch roller 61 can be separated from the first transport roller 60 while maintaining the state where the first transport roller 60 is biased.

  Further, according to the present embodiment, when the pinch roller 61 is separated from the first conveying roller 60 against the biasing force of the coil spring 91, the biasing force of the coil spring 91 is changed from the pinch roller 61 to the convex portion 162, This is transmitted to the first conveying roller 60 via the shaft 157, the eccentric cam 160, and the contact member 161. That is, according to the present embodiment, the coil spring 91 can be used in order to realize the pressing of the first conveying roller 60 by the contact member 161.

  Further, if at least one of the pinch roller 61 or the contact member 161 moves while the first transport roller 60 is rotating, the position of the recording paper 12 in contact with the first transport roller 60 may be shifted. is there. According to this embodiment, the adjustment of the urging force that may be accompanied by the movement of the pinch roller 61 and the contact member 161 and the pressing of the contact member 161 against the first transport roller 60 stop the rotation of the first transport roller 60. Since it is executed when the recording paper 12 is being used, it is possible to prevent the positional deviation of the recording paper 12 as described above.

  In addition, when the position of the first transport roller 60 is shifted, the distance between the movement amount of the recording paper 12 calculated by the microcomputer 130 based on the rotation amount of the first transport roller 60 and the actual movement amount of the recording paper 12. In addition, an error occurs. However, according to the present embodiment, it is possible to prevent the first transport roller 60 from being displaced. Therefore, it is possible to prevent the movement amount from being generated.

  Further, if the position of the first transport roller 60 is shifted, the position of the second transport roller 62 connected to the first transport roller 60 via the belt mechanism 120 may be shifted. If the position of the second conveying roller 62 is shifted, the position of the recording paper 12 being nipped and conveyed by the second conveying roller 62 and the spur 63 may be shifted. However, according to the present embodiment, it is possible to prevent the first transport roller 60 from being displaced. Therefore, it is possible to prevent the positional deviation of the recording paper 12 being nipped and conveyed by the second conveyance roller 62 and the spur 63.

  Further, according to the present embodiment, since the nip force is not applied to the recording paper 12 that has been nipped by the first conveyance roller 60 and the pinch roller 61, a force in the conveyance direction acts on the recording paper 12, It is possible to avoid the phenomenon that the recording paper 12 is transported in the transport direction more than originally assumed. In addition, as described above, the first conveying roller 60 is urged from the abutting member 161 instead of being urged from the pinch roller 61, so that the displacement of the first conveying roller 60 can be prevented. That is, according to the present embodiment, the above phenomenon can be avoided without causing the positional deviation of the first conveying roller 60.

  Further, according to the present embodiment, the pressing of the contact member 161 against the first transport roller 60 is realized simply by bringing the contact member 161 separated from the first transport roller 60 into contact with the first transport roller 60. be able to.

  Further, according to the present embodiment, the contact member 161 and the pinch roller 61 are in contact with the first transport roller 60 from the same direction, so that the possibility that the position of the first transport roller 60 is shifted can be reduced.

[Modification 1 of Embodiment]
In the above-described embodiment, the convex portion 162 adjusts the urging force of the pinch roller 61 against the first conveying roller 60 by the coil spring 91 by moving the eccentric cam 160 toward and away from the contact member 161. However, the convex portion 162 may adjust the biasing force without separating the eccentric cam 160 from the contact member 161. That is, in the above-described embodiment, the convex portion 162 adjusts the urging force between a predetermined value and zero. However, in Modification 1, the convex portion 162 adjusts the urging force to the first predetermined force. The adjustment is made between the value and a second predetermined value that is smaller than the first predetermined value and larger than zero.

  For example, in the above-described embodiment, the eccentric cam 160 and the contact member 161 are separated from each other in FIG. 5B, but in the first modification, the first cam of the eccentric cam 160 in FIG. The distance R1 may be increased and brought into contact with the contact member 161. However, the increased first distance R1 is shorter than the second distance R2. Accordingly, even if the eccentric cam 160 is in contact with the contact member 161 in FIG. 5B, the first distance R1 is shorter than the second distance R2, and thus the state shown in FIG. The biasing force can be reduced.

[Modification 2 of the embodiment]
In the above-described embodiment, the contact member 161 is passed through the shaft 34 of the first conveying roller 60, and the eccentric cam 160 is in contact with and away from the contact member 161. However, the third posture (an example of the third posture of the present invention) in which the contact member of the present invention is in contact with the first transport roller 60 and the fourth posture (the first posture of the present invention) separated from the first transport roller 60. The posture may be changed to (an example of four postures).

  As a configuration for realizing the second modification, for example, in the above-described embodiment, the eccentric cam 160 may be an example of the contact member of the present invention without providing the contact member 161. The eccentric cam 160 may be configured to be large enough to contact the first conveying roller 60. Then, the eccentric cam 160 can change its posture between a third posture in contact with the first conveying roller 60 and a fourth posture separated from the first conveying roller 60.

  Even in the configuration as described above, as in the above-described embodiment, the abutment mechanism 90 is configured such that when the urging force of the pinch roller 61 against the first transport roller 60 by the coil spring 91 is weakened by the convex portion 162, By changing the posture of the eccentric cam 160 from the fourth posture to the third posture, the eccentric cam 160 can be pressed against the first conveying roller 60.

[Modification 3 of the embodiment]
In the above-described embodiment, the shaft 157 of the planet gear 156 provided in the contact mechanism 90 which is an example of the contact mechanism of the present invention and the convex portion 162 which is an example of the adjustment mechanism of the present invention are in contact with each other. It was possible. That is, the contact mechanism of the present invention and the adjustment mechanism of the present invention are interlocked with each other with a mechanical relationship. However, the contact mechanism of the present invention and the adjustment mechanism of the present invention may be driven independently without having a mechanical relationship.

  For example, a contact member 161 that urges the first drive roller 60 upward can be moved in the vertical direction 7 by the first motor, and the shaft 157 of the planet gear 156 is different from the first motor. It may be movable in the vertical direction 7 by the motor. That is, the contact member 161 and the shaft 157 of the planet gear 156 may be driven independently.

  In this case, the drive timing of the contact member 161 and the shaft 157 of the planet gear 156 is such that the pressure contact force to the first transport roller 60 is always applied from either the pinch roller 61 or the contact member 161. Controlled by the microcomputer 130.

[Modification 4 of the embodiment]
In the above-described embodiment, the urging force of the pinch roller 61 against the first transport roller 60 by the coil spring 91 is adjusted by separating the pinch roller 61 from the first transport roller 60. However, the urging force may be adjusted without separating the pinch roller 61 from the first conveying roller 60.

  For example, in the above-described embodiment, even when the eccentric cam 160 rotates until the diameter of the eccentric cam 160 on the contact member 161 side reaches the second distance R2, the pinch roller 61 is completely removed from the first conveying roller 60. The second distance R2 may be adjusted so as not to leave the distance. In other words, in FIG. 9A, the diameter of the eccentric cam 160 may be adjusted so that the pressure contact force of the pinch roller 61 indicated by the solid line to the first conveying roller 60 does not become zero.

DESCRIPTION OF SYMBOLS 10 ... MFP 60 ... 1st conveyance roller 61 ... Pinch roller 62 ... 2nd conveyance roller 63 ... Spur 65 ... Conveyance path 74 ... Encoder disk 75 ... Light Sensor 90 ... Contact mechanism 91 ... Coil spring 130 ... Microcomputer 140 ... Sheet detection unit 157 ... Shaft 160 ... Eccentric cam 161 ... Contact member 162 ... Projection

Claims (9)

A conveyance path for guiding a recording medium;
A driving roller which is provided in the conveying path and rotates by being applied with a driving force from a driving source;
A driven roller that is provided opposite to the driving roller and that conveys the recording medium between the driving roller and conveys the recording medium along the conveying path;
A biasing member that biases the driven roller against the driving roller;
An adjustment mechanism for adjusting the urging force of the driven roller against the drive roller by the urging member;
A contact mechanism having a contact member capable of contacting the drive roller;
A medium position detection unit that detects that the rear end of the recording medium in the conveyance direction is conveyed to a predetermined position upstream of the nip position of the drive roller and the driven roller in the conveyance direction ;
The adjustment mechanism weakens the urging force of the driven roller against the drive roller by the urging member based on the detection result of the medium position detection unit,
The conveying mechanism presses the abutting member against the driving roller when the urging force of the driven roller against the driving roller by the urging member is weakened by the adjusting mechanism. The driven roller is capable of changing its posture into a first posture in contact with the driving roller and a second posture separated from the driving roller,
2. The conveyance according to claim 1, wherein the adjustment mechanism adjusts the biasing force by changing the posture of the driven roller from the first posture to the second posture against the biasing force of the biasing member. apparatus. The contact mechanism is
The contact member is passed through the shaft of the drive roller;
A rotating shaft extending in the same direction as the shaft of the driven roller and movable to a first position contacting the adjusting mechanism and a second position spaced from the adjusting mechanism;
A first peripheral surface provided on the rotary shaft, the first peripheral surface having a first distance from the rotary shaft to the peripheral surface, and a second peripheral surface having a diameter from the rotary shaft to the peripheral surface being longer than the first distance. A rotating cam in which the second peripheral surface is brought into contact with and separated from the abutting member by rotation of the rotating shaft,
The rotating shaft moves to the first position when the second peripheral surface comes into contact with the contact member, contacts the adjustment mechanism, and the second peripheral surface moves away from the contact member. To move to the second position and away from the adjustment mechanism,
The adjustment mechanism abuts on the rotation shaft to change the posture of the driven roller from the first posture to the second posture against the urging force of the urging member, and from the rotation shaft. The conveying device according to claim 2, wherein the driven roller is changed in posture from the second posture to the first posture by the urging force of the urging member by being separated.   4. The adjusting mechanism according to claim 1, wherein after the abutting mechanism presses the abutting member against the driving roller, the urging force of the driven roller against the driving roller by the urging member is adjusted. 5. The conveying apparatus as described. The adjustment mechanism adjusts the urging force of the driven roller to the drive roller by the urging member on the condition that the rotation of the drive roller is stopped,
5. The transport device according to claim 1, wherein the contact mechanism presses the contact member against the drive roller on condition that rotation of the drive roller is stopped. A rotating body that rotates integrally with the drive roller and is provided with a plurality of detected portions along a circumferential direction concentric with the rotation center;
A detection unit that is provided at a position that can be opposed to the detected unit by rotation of the rotating body, and that detects the detected unit ;
Conveying apparatus according to any one of claims 1-5, further comprising a calculation unit for calculating the amount of rotation of the drive roller based on the detection frequency of the detected part by the detection unit. A first roller provided at a position different from the driving roller and the driven roller in the conveying path;
A second roller that is provided facing the first roller, and is capable of being conveyed along the conveyance path with a recording medium sandwiched between the first roller and the first roller;
The transport apparatus according to claim 1, further comprising: a drive transmission mechanism that is connected to the drive roller and the first roller and transmits a rotational force of the drive roller to the first roller. The contact member can change its posture to a third posture in contact with the drive roller and a fourth posture separated from the drive roller,
The contact mechanism changes the posture of the contact member from the fourth posture to the third posture when the biasing force of the driven roller to the drive roller by the biasing member is weakened by the adjustment mechanism. The conveying device according to claim 1, wherein the contact member is pressed against the driving roller. Abutting direction against the drive roller of said abutment member, the conveying device according to any one of claims 1 to 8 in the same direction as the contact facing for the drive roller of the driven roller.

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