JP2017178618A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a friction load which a recording paper receives and effectively reduce a rubbing sound and paper dust of the recording paper which passes a transportation path.SOLUTION: In an image formation device 1, an actuator 50 is energized in one rotational direction with a rotation support shaft 53 as a center, and a first arm 51 enters a transportation path 190, while a second arm 52 and a guide roller 54 recede from the transportation path 190, and when the first arm 51 is shifted along a direction receding from the transportation path 190, the actuator 50 rotates in the opposite direction with the rotation support shaft 53 as a center, so that the second arm 52 approaches the transportation path 190 and the guide roller 54 enters the transportation path 190.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus that forms an image on a recording sheet, and more particularly to a technique for conveying the recording sheet.

  In recent years, there has been an increasing demand for noise reduction in office equipment, and image forming apparatuses such as copiers, printers, and multifunction machines are no exception. As the noise of the image forming apparatus, there are mainly driving sound emitted from a motor, a gear, and the like, and conveyance sound accompanying conveyance of recording paper. While the driving sound is a steady noise, the conveying sound is an unsteady noise that is generated when the recording paper is conveyed.

  This transport sound also includes a collision sound that occurs when the recording paper collides with some member and a rubbing sound that occurs when the recording paper rubs against the guide wall of the transport path, but the rubbing sound has greater acoustic power, Reduction of rubbing noise is regarded as important. In particular, when pulling up the recording paper sent out from the paper feed cassette in the horizontal direction, the recording paper is conveyed through a curved conveyance path upward, so that the recording paper moves while making strong contact with the guide wall of the conveyance path. And a loud rubbing sound is generated. At the same time, paper dust generated from the recording paper increases. Further, the contact may cause slippage of the transport roller for transporting the recording paper.

  For this reason, for example, in Patent Document 1, a plurality of driven rotating bodies are provided on the outer peripheral guide wall that forms the curved portion of the conveyance path, and the recording paper is guided by the driven rotating bodies, so that the recording paper and the outer peripheral guide are provided. It reduces friction between walls and reduces rubbing noise and paper dust.

  Also, in Patent Document 2, a roller is provided on the inner peripheral guide wall that forms the curved portion of the conveyance path, and the recording paper is guided by the roller to reduce friction between the recording paper and the inner peripheral guide wall. This reduces rubbing noise and paper dust.

JP-A-2005-350202 JP 2004-239937 A

  However, in Patent Document 1, since the plurality of driven rotating bodies are always fixedly provided on the guide wall of the conveyance path, the conveyance path becomes narrow. Similarly, in Patent Document 2, since the rollers are fixedly provided on the guide wall of the conveyance path, the conveyance path becomes narrow. When passing through a narrow portion of the transport path, the recording paper is easily subjected to a large frictional load, which causes paper jams and paper dust. Further, since the driven rotating body or the roller has a level difference with respect to the guide wall of the conveyance path, the recording paper may be caught at the level difference and a paper jam may occur. Further, as the number of driven rotors and rollers increases, the risk of the recording paper getting caught increases and the cost increases. In addition, when a plurality of driven rotating bodies and rollers are provided in the width direction of the recording paper, the recording paper undulates in the width direction of the recording paper, and in this state the recording paper is sandwiched between a pair of conveying rollers, Wrinkles appear on the paper.

  Alternatively, if the conveyance path is widened, the friction load applied to the recording paper can be reduced, or the risk of the recording paper being caught on the step is reduced, but the space for securing the conveyance path is widened. It is difficult to reduce the size of the image forming apparatus.

  The present invention has been made in view of the above circumstances, and reduces the frictional load applied to the recording paper without increasing the size of the apparatus and effectively eliminates the rubbing noise and paper dust of the recording paper passing through the conveyance path. It is an object to make it possible to reduce it to a low level.

An image forming apparatus according to an aspect of the present invention has a curved portion, a conveyance path through which a sheet is conveyed, a first conveyance roller that is provided in the conveyance path and conveys the sheet,
A second conveying roller that is disposed downstream of the first conveying roller and conveys the sheet; and a detecting unit that detects the sheet passing through the conveying unit, and the detecting unit contacts the sheet. An actuator that contacts and can rotate about a rotation axis; and a sensor that detects rotation of the actuator; the actuator extends outward from the rotation axis and can contact the seat A lever, a guide roller rotatably supported at the tip of a pair of support arms extending in a direction different from the lever from the rotating shaft, and a cover projecting from the rotating shaft and detectable by the sensor. The actuator includes a detection piece, and the actuator protrudes into the conveyance path on the downstream side in the conveyance direction of the curved portion, and the leading edge of the sheet can contact the actuator. A standby position, and the leading end passes through the lever portion and is pressed by the sheet stretched between the first conveying roller and the second conveying roller, and the lever portion is retracted from the conveying path. The position of the guide roller can be changed to a guide position where the guide roller protrudes from the curved portion into the conveyance path and rotates in contact with the sheet.

  According to the present invention, when the recording paper is transported through the transport path, when the first arm is pushed by the recording paper and moves in a direction away from the transport path, the actuator rotates in the reverse direction around the rotation support shaft. The second arm approaches the conveyance path, and the guide roller enters the conveyance path and contacts the recording paper. For this reason, it is possible to reduce the friction load applied to the recording paper and to effectively reduce the rubbing sound and paper dust of the recording paper passing through the conveyance path. In addition, since the above-described effect can be obtained by disposing the actuator in the conveyance path of the recording paper, the apparatus is not enlarged.

1 is a front sectional view showing the structure of an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing the vicinity of a curved portion of a conveyance path through which a recording sheet fed from a sheet feeding cassette passes, viewed from the side. It is a perspective view which shows the actuator provided in the curved part of a conveyance path. FIG. 6 is a cross-sectional view showing an operating state of an actuator at the start of feeding of recording paper from a paper feed cassette. It is sectional drawing which shows the operation state of an actuator when the front-end | tip of a 1st arm is pushed up with the recording paper. FIG. 6 is a cross-sectional view illustrating an operating state of an actuator when a leading end of a recording sheet is sandwiched and pulled up by a pair of conveying rollers.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a front sectional view showing the structure of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 according to the present embodiment is configured by providing an image reading device (ISU) 5, an operation unit 47, an image forming unit 120, a fixing device 13, a paper feeding unit 14, and the like in the apparatus main body 2. Is done.

  The operation unit 47 is operated by a user and accepts execution instructions such as an image forming operation and an image reading operation.

  When performing an image reading operation, the image reading device 5 optically reads an image of a document and generates image data. Image data generated by the image reading device 5 is stored in a built-in HDD or a computer connected to a network.

  When performing an image forming operation, the image data generated by the image reading operation described above, image data received from a user terminal device such as a computer or smartphone connected to a network, or image data stored in a built-in HDD Based on this, the image forming unit 120 forms a toner image on a recording paper (an example of a sheet) P as a recording medium supplied from the paper supply unit 14.

  The image forming unit 120 includes a magenta image forming unit 12M, a cyan image forming unit 12C, a yellow image forming unit 12Y, and a black image forming unit 12Bk. Each of the image forming units 12M, 12C, 12Y, and 12Bk exposes the surface of the photosensitive drum 122, the charging device that uniformly charges the surface of the photosensitive drum 122, and the surface of the photosensitive drum 122 to the surface. An exposure device (LSU) 123 that forms an electrostatic latent image, a developing device 124 that develops the electrostatic latent image on the surface of the photosensitive drum 122 into a toner image using toner, and a primary transfer roller 126 And each.

  When performing color printing, in each of the image forming units 12M, 12C, 12Y, and 12Bk, the surface of the photosensitive drum 122 is uniformly charged and then exposed, and the surface corresponds to an image of a color component of color. An electrostatic latent image is formed, the electrostatic latent image on the surface of the photosensitive drum 122 is developed, a toner image of the color component is formed on the photosensitive drum 122, and the toner image is driven by the primary transfer roller 126. Primary transfer is performed on the intermediate transfer belt 125 stretched between the roller 125A and the driven roller 125B.

  The intermediate transfer belt 125 has an image bearing surface on which the toner image is transferred on the outer circumferential surface thereof, and is driven by the driving roller 125 </ b> A while being in contact with the circumferential surface of the photosensitive drum 122. The intermediate transfer belt 125 runs endlessly between the driving roller 125A and the driven roller 125B while being synchronized with each photosensitive drum 122.

  The toner images of the respective color components transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 with the transfer timing adjusted to become a color toner image. The secondary transfer roller 210 transfers the color toner image formed on the surface of the intermediate transfer belt 125 from the paper supply unit 14 to the conveyance path 190 in the nip portion N between the secondary transfer roller 210 and the intermediate transfer belt 125. Secondary transfer is performed on the recording paper P that has been conveyed through.

  Thereafter, the recording paper P is heated and pressurized by the fixing device 13, the toner image on the recording paper P is fixed by thermocompression bonding, and the recording paper P is discharged to the discharge tray 151 through the discharge roller pair 159.

  The paper feeding unit 14 includes a paper feeding cassette 141 that stores a plurality of recording papers P. The recording paper P is pulled out from the paper feeding cassette 141 by a pickup roller 142, and a pair of paper feeding rollers (an example of a first transporting roller). ) 143 sends out the recording paper P to a pair of conveyance rollers (an example of a second conveyance roller) 144 in the conveyance path 190.

  By the way, the rubbing sound generated when the recording paper P slides on the guide wall of the conveyance path 190 is unsteady noise and is easily noticeable, and has high acoustic power. For this reason, it is desirable to reduce the rubbing sound. In particular, when the recording paper P sent out from the paper feed cassette 141 in the horizontal direction is pulled upward through the curved portion of the transport path 190 and transported, the recording paper P is against the curved guide wall of the transport path 190. When the contact is strong, the frictional load of the recording paper P against the guide wall increases, and a large rubbing sound is generated. At the same time, paper dust generated from the recording paper P increases.

  Further, when a roller that contacts the recording paper P is fixedly provided on the curved guide wall of the conveyance path 190, although the rubbing sound and paper dust can be reduced, the leading edge of the recording paper P is caught by the roller. Problems arise.

  Therefore, in the present embodiment, a guide roller is provided so as to be freely inserted into and removed from the curved portion of the conveyance path 190 through which the recording paper P delivered from the paper feed cassette 141 passes, and when the leading edge of the recording paper P passes through the curved portion. After the guide roller is retracted from the transport path 190 and the leading edge of the recording paper P passes through the curved portion, the guide roller is projected from the curved guide wall of the transport path 190 to the transport path 190, and the guide roller is moved to the recording paper. The frictional load on the recording paper P is reduced by contacting the recording paper P. For this reason, rubbing sound and paper dust are reduced, and the problem that the leading edge of the recording paper P is caught by the guide roller does not occur.

  Next, the guide roller of this embodiment will be described. FIG. 2 is a cross-sectional view schematically showing the vicinity of the curved portion of the transport path 190 through which the recording paper P delivered from the paper feed cassette 141 passes is seen from the side.

  As shown in FIG. 2, the recording paper P sent out from the paper feed roller pair 143 of the paper feed cassette 141 is transported to the transport roller pair 144 through a transport path 190 that curves upward from the vicinity of the paper feed roller pair 143. Then, it is pulled up by the conveyance roller pair 144 and conveyed to the nip portion N (shown in FIG. 1) between the secondary transfer roller 210 and the intermediate transfer belt 125.

  The conveyance path 190 is formed by an inner guide wall 191 and an outer guide wall 192. Both the inner guide wall 191 and the outer guide wall 192 face in a substantially horizontal direction on the paper feed roller pair 143 side and rise in a substantially vertical direction on the transport roller pair 144 side to form a curved portion 190a of the transport path 190. Yes. The inner guide wall 191 is an example of an inner conveyance guide in the claims. The outer guide wall 192 is an example of an outer conveyance guide in the claims.

  An actuator 50 and a recording sheet presence / absence detection sensor (an example of a sensor in the claims) 60 are provided as detection units in the vicinity of the curved portion 190a of the conveyance path 190. The actuator 50 is provided between the first arm 51, the second arm 52, the first arm 51, the second arm 52, a rotation support shaft 53 that connects the arms 51, 52, and the tip of the second arm 52. A provided guide roller 54 and a detected body 55 projecting from the rotation support shaft 53 are provided. The first arm 51 and the second arm 52 form an L shape that is curved at the position of the rotation support shaft 53. That is, the rotation support shaft 53 is provided at the coupling portion between the first arm 51 and the second arm 52. In addition, the 1st arm 51 is an example of the lever part in a claim. The detected object 55 is an example of a detected piece in the claims.

  In the transport path 190, the recording paper P is transported in the transport direction A. The actuator 50 is a rotating support shaft disposed on the main part 2 of the apparatus that is out of the transport path 190 with the first arm 51 and the second arm 52 disposed on the downstream side and the upstream side in the transport direction A of the recording paper P, respectively. 53 is supported so as to be rotatable about the center.

  The actuator 50 is urged in a predetermined rotation direction around the rotation support shaft 53, for example, in a clockwise direction in FIG. The urging force in the clockwise direction with respect to the actuator 50 may be applied by a weight balance of the actuator 50 around the rotation support shaft 53, or may be applied by a spring or the like. When the urging force causes the actuator 50 to rotate in the clockwise direction in FIG. 2 about the rotation support shaft 53, the first arm 51 enters the crossing path 190 and intersects, and the guide roller at the tip of the second arm 52. 54 comes off (retreats) from the transport path 190.

  Further, as shown by a broken line, when the actuator 50 rotates counterclockwise around the rotation support shaft 53 against the urging force, the first arm 51 rotates in a direction away from the conveyance path 190. At the same time, the second arm 52 rotates and the guide roller 54 at the tip of the second arm 52 enters the transport path 190 and protrudes inside the transport path 190 from the inner guide wall 191.

  That is, the actuator 50 can be changed in posture between the standby posture and the guide position. The standby posture is a posture in which the first arm 51 protrudes into the conveyance path 190 on the downstream side in the conveyance direction of the recording paper P with respect to the bending portion 190 a and the leading edge of the recording paper P can contact the first arm 51. . Further, the guide position is pressed by the recording paper P in a state where the leading end passes through the first arm 51 and is stretched between the paper feed roller pair 143 and the transport roller pair 144, so that the first arm 51 is transported. In addition to rotating in the direction of retreating from 190, the guide roller 54 protrudes from the curved portion 190a into the conveyance path 190 and rotates in contact with the recording paper P.

  Further, the guide roller 54 protrudes from the inner guide wall 191 into the conveyance path 190. When the actuator 50 is in the guide position, the recording paper P is separated from the inner guide wall 191. In the standby position, the first arm 51 is disposed outside the conveyance path 190 with a tip portion passing through the outer guide wall 192.

  In the inner guide wall 191 and the outer guide wall 192 of the transport path 190, an opening 191A that allows the first arm 51 to enter and exit the transport path 190 is formed in a partial region in the recording paper width direction orthogonal to the transport direction A. In addition, another opening 191 </ b> B is formed in the inner guide wall 191 so that the guide roller 54 at the tip of the second arm 52 can enter and leave the conveyance path 190.

  One actuator 50 and one guide roller 54 are provided at the center of the transport path 190 in the direction orthogonal to the transport direction A of the recording paper P (the width direction of the recording paper P).

  The recording paper presence / absence detection sensor 60 is, for example, a transmissive optical sensor including a light emitting element and a light receiving element, and whether the detected object 55 that rotates together with the rotation support shaft 53 of the actuator 50 is at the position of the recording paper presence / absence detection sensor 60. Detect whether or not. As described later, based on the detection output of the recording paper presence / absence detection sensor 60, the presence / absence of the recording paper P passing through the curved portion 190a of the conveyance path 190 can be determined.

  FIG. 3 is a perspective view showing the actuator 50. As shown in FIG. 3, a first arm 51 and a detection object 55 project from the center of the rotation support shaft 53 in the length direction, and a pair of second arms are provided at positions near both ends of the rotation support shaft 53. 52 is protrudingly provided. The guide roller 54 has a cylindrical shape, and a shaft of the guide roller 54 is rotatably supported by a pair of second arms 52. Both ends of the rotation spindle 53 are disposed outside the conveyance path 190 with respect to the inner guide wall 191 and are rotatably supported. The first arm 51 and the second arm 52 are rotationally supported so that the angle θ of the second arm 52 with respect to the first arm 51 and the angle θ (FIG. 4) on the side toward the conveyance path 190 becomes an obtuse angle. The shaft 53 is connected.

  In such a configuration, as shown in FIG. 4, at the start of feeding of the recording paper P from the paper feed cassette 141, the actuator 50 is urged and rotated clockwise around the rotation support shaft 53, and the first As the arm 51 enters and intersects the transport path 190, the guide roller 54 at the tip of the second arm 52 is retracted from the transport path 190.

  Therefore, the inner portion of the curved portion 190a of the conveyance path 190, that is, the corner portion of the conveyance path 190 shown in FIG. 4 is opened, and the leading edge of the recording paper P is curved without being interfered by the guide roller 54. Passing through the portion 190a, the direction is changed from the horizontal direction to the vertical direction while being in sliding contact with the outer guide wall 192 and guided to the transport roller pair 144.

  Further, when the actuator 50 is rotated by being urged clockwise about the rotation support shaft 53 in this way, the detection target 55 of the actuator 50 is the light receiving element and the light emitting element of the recording paper presence / absence detection sensor 60. , The light of the light emitting element is blocked by the detected body 55, and the output of the light receiving element is at a low level. Based on the low level output of the light receiving element of the recording paper presence / absence detection sensor 60, it is determined that there is no recording paper P passing through the curved portion 190a of the transport path 190.

  As shown in FIG. 5, when the leading edge of the recording paper P conveyed in the conveying path 190 reaches the leading edge of the first arm 51 of the actuator 50, the leading edge of the recording paper P presses the first arm 51 to record. The leading end of the first arm 51 is pushed up by the paper P. At this time, the actuator 50 rotates counterclockwise in the counterclockwise direction E (FIG. 5) against the urging force 53 toward the position where the first arm 51 deviates from the conveyance path 190. While rotating, the second arm 52 moves in a direction approaching the transport path 190, and the guide roller 54 at the tip of the second arm 52 enters the transport path 190.

  At this time, as shown in FIG. 5, the detection target 55 of the actuator 50 moves to be detached from the recording paper presence / absence detection sensor 60, and the light from the light emitting element of the recording paper presence / absence detection sensor 60 is received by the light receiving element. The output of the light receiving element of the paper presence / absence detection sensor 60 becomes high level. Based on the high level output of the light receiving element of the recording paper presence / absence detection sensor 60, it is determined that there is recording paper P passing through the curved portion 190a of the conveyance path 190.

  When the leading edge of the recording paper P passes between the leading edge of the first arm 51 and the outer guide wall 192 and reaches the nip region of the conveying roller pair 144, as shown in FIG. The leading edge of P is sandwiched, and conveyance to the recording paper P by the conveyance roller pair 144 is started. After the conveyance of the recording paper P by the conveyance roller pair 144 is started, the driving of the paper feed roller pair 143 is stopped, and the paper feed roller pair 143 shifts to driven rotation. As a result, the recording paper P is tensioned, and the recording paper P may approach the inner guide wall 191 of the transport path 190 in some cases. As the recording paper P approaches the inner guide wall 191, the leading end of the first arm 51 is further pressed by the recording paper P, and the first arm 51 is further removed from the transport path 190 (on the inner guide wall 191 side). The actuator 50 further rotates in the counterclockwise direction E against the biasing force, and the second arm 52 further rotates and moves toward the inside of the conveyance path 190, and the tip of the second arm 52 is moved. The guide roller 54 further enters the conveyance path 190 and protrudes more inside the conveyance path 190 than the inner guide wall 191. In this state, while the actuator 50 is urged clockwise around the rotation support shaft 53, a moment in the counterclockwise direction E acts on the tip of the first arm 51 due to the force received from the recording paper P. To do. Further, when the guide roller 54 at the tip of the second arm 52 abuts on the recording paper P, the rotational movement is suppressed. As a result, the biasing force and the moment of both are balanced, the position of the guide roller 54 is substantially maintained, the recording paper P is conveyed while being in contact with the guide roller 54, and the guide roller 54 rotates.

  Thus, in a state where the guide roller 54 at the tip of the second arm 52 has entered the transport path 190, a tangent line C that contacts the peripheral surface of the guide roller 54 and the outer periphery of the tip of the first arm 51 extends from the inner guide wall 191 of the transport path 190. Separate. Further, a straight line D connecting the nip region of the paper feed roller pair 143 and the circumferential surface of the guide roller 54 is separated from the inner guide wall 191 of the transport path 190. The recording paper P is curved in contact with the circumferential surface of the guide roller 54, extends substantially along the tangent line C on the downstream side in the transport direction A of the recording paper P from the guide roller 54, and more than the guide roller 54. Since the recording paper P extends substantially along the straight line D on the upstream side in the conveyance direction A of the recording paper P, the recording paper P does not contact only the guide roller 54 and contact the inner guide wall 191. Therefore, the frictional load that the recording paper P receives is only that received from the rolling resistance of the guide roller 54.

  Subsequently, when the recording paper P is further transported by the transport roller pair 144 and the rear end of the recording paper P passes the front end of the first arm 51, the actuator 50 is attached in the clockwise direction around the rotation support shaft 53. Rotated to return to the original state shown in FIG.

  As described above, in this embodiment, the guide roller 54 at the tip of the second arm 52 retreats from the transport path 190 and is out of the transport path 190 at the start of feeding of the recording paper P by the paper feed roller pair 143. The inside of the curved portion 190a of the conveyance path 190 is opened, the leading edge of the recording paper P is not caught by the guide roller 54, and the leading edge of the recording paper P smoothly passes through the curved portion 190a and the conveying roller pair 144. For this reason, a paper jam does not occur.

  When the leading edge of the recording paper P reaches the transport roller pair 144 and is pulled up, the recording paper P is tensioned, and the leading edge of the first arm 51 is reliably pushed up by the recording paper P, so that the first arm 51 moves away from the conveyance path 190, the second arm 52 approaches the conveyance path 190, and the guide roller 54 at the tip of the second arm 52 protrudes more inside the conveyance path 190 than the inner guide wall 191. To do. For this reason, the recording paper P does not come into contact with only the guide roller 54 and comes into contact with the inner guide wall 191, the frictional load of the recording paper P is effectively reduced, and the recording paper P comes into sliding contact with the inner guide wall 191. In this case, the rubbing sound and paper dust generated in the recording paper P are reduced, and further, the conveyance roller pair 144 does not slip with respect to the recording paper P.

  Further, since one guide roller 54 of the actuator 50 is provided at the center of the conveyance path 190 in the direction orthogonal to the conveyance direction A of the recording paper P (width direction of the recording paper P), the structure becomes complicated and the cost is reduced. There will be no increase. Further, as compared with the case where a plurality of rollers are arranged in parallel in the direction orthogonal to the conveyance direction A of the recording paper P, the recording paper P becomes difficult to wave in the width direction of the recording paper P and is sandwiched between the conveyance roller pair 144. It is possible to prevent the phenomenon that wrinkles are sometimes generated on the recording paper P.

  Further, when the guide roller 54 is retracted from the transport path 190, the transport path 190 becomes wider and the leading edge of the recording paper P smoothly passes through the transport path 190, so there is no need to make the transport path 190 particularly wide. Therefore, it is possible to reduce the size of the image forming apparatus 1.

  Further, based on the detection output of the recording paper presence / absence detection sensor 60, the presence / absence of the recording paper P passing through the curved portion 190a of the transport path 190 is determined. Therefore, the actuator 50 is used both for reducing the rubbing sound and paper dust and for determining the presence or absence of the recording paper P, so that the number of parts can be reduced.

  In the above-described embodiment, the actuator 50 is provided in the vicinity of the curved portion 190a of the transport path 190 through which the recording paper P sent out from the paper feed cassette 141 passes. Even if it is provided in the curved portion), the same effect is obtained.

  The image forming apparatus according to the present invention is not limited to the one described in the above embodiment, and may be another type of image forming apparatus such as a copying machine, a printer, or a facsimile machine.

  The configuration described with reference to FIGS. 1 to 6 is only one embodiment of the present invention, and is not intended to limit the present invention to the configuration and processing.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 5 Image reading apparatus 13 Fixing apparatus 14 Paper feed part 47 Operation part 50 Actuator 51 1st arm 52 2nd arm 53 Support shaft 54 Guide roller 55 Detected object 60 Paper sensor 120 Image formation part 141 Supply Paper cassette 142 Pickup roller 143 Paper feed roller pair 144 Transport roller pair

Claims (4)

A conveyance path having a curved portion and conveying a sheet;
A first conveying roller that is provided in the conveying path and conveys the sheet;
A second transport roller disposed downstream of the first transport roller to transport the sheet;
A detection unit that detects the sheet passing through the conveyance unit,
The detector is
An actuator that abuts the seat and is rotatable about a rotation axis;
A sensor for detecting the rotation of the actuator,
The actuator is
A lever portion extending outward from the rotating shaft and capable of contacting the seat;
A guide roller rotatably supported at the tip of a pair of support arms extending in a direction different from the lever portion from the rotation shaft;
And a detected piece that protrudes from the rotating shaft and can be detected by the sensor,
The actuator is
A standby posture in which the lever portion protrudes into the conveyance path on the downstream side in the conveyance direction of the bending portion, and the leading edge of the sheet can contact;
The leading end passes through the lever portion and is pressed by the sheet stretched between the first conveying roller and the second conveying roller, and the lever portion rotates in a direction to retract from the conveying path. In addition, the image forming apparatus is capable of changing a posture to a guide position where the guide roller protrudes from the curved portion into the conveyance path and rotates in contact with the sheet. The transport path has an inner transport guide and an outer transport guide,
The guide roller protrudes from the inner conveyance guide into the conveyance path,
The image forming apparatus according to claim 1, wherein the sheet is separated from the inner conveyance guide in a state where the actuator is disposed at the guide position.   The image forming apparatus according to claim 1, wherein one guide roller is provided at a center of the conveyance path in the width direction of the sheet, which is a direction orthogonal to the conveyance direction of the sheet.   4. The image forming apparatus according to claim 1, wherein a tip end portion of the lever portion is disposed outside the conveyance path at the standby position so as to penetrate the outer conveyance guide. 5.

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