JP2006189569A - Paper output mechanism, fixing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper output mechanism capable of enhancing storage performance by preventing the trailing end of a paper from being left on an output roller, and to provide an image forming apparatus equipped with the paper output mechanism. <P>SOLUTION: The paper output mechanism is provided with a paper output means 34, a detecting means 100 for detecting the paper in transport, and a paper depressing means 102 which deviates from a paper output path at least in a period when the paper is output by the paper output means 34, and which works so that the paper detected by the detecting means 100 may depress the trailing end of the paper just output by the paper output means 34. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a paper discharge mechanism of an image forming apparatus such as a printer, a copier, or a facsimile, a fixing device having the same, and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a copying machine, or a facsimile, a sheet discharged by two discharge rolls having a nip is stored in a discharge tray. However, if the trailing edge of the paper passes through the nip between the two discharge rolls, the paper conveying force is lost, the trailing edge of the paper remains on the discharge roll, and is pushed out to the paper discharge tray at the leading edge of the next paper. The property was poor. In particular, when the amount of toner on the paper increases as in a color printer, roll marks are likely to occur due to the nip of the discharge roll, so the nip pressure cannot be increased to increase the conveying force, and the trailing edge of the paper tends to remain. It was. Further, even when the rear end portion of the sheet is curled to the side opposite to the image forming side, the remaining rear end cannot be prevented by a conventional kick roll or the like.

  So far, a paper discharge mechanism (Patent Document 1) has been disclosed in which a flapper that is rotated downward by its own weight after being discharged by the discharge roll has been arranged to improve the capacity of paper discharged by the discharge roll. Yes. Further, after discharging by the discharge roll, a sheet discharge mechanism (Patent Document 2) in which a pressing member having an inclined portion whose lower end portion is inclined downward in the sheet discharge direction, or a sheet is directed toward the sheet receiving surface of the tray. Disclosed is a paper discharge mechanism (Patent Document 3) in which a seating member formed by an arm or the like is arranged, and discloses a paper discharge mechanism that improves the paper storage property after paper discharge by a discharge roll. .

JP 2001-348155 A JP 2002-249270 A JP 2003-40506 A

  However, in the methods of Patent Documents 1 to 3 described above, the leading edge of the paper after being discharged by the discharging roll is also pressed, so that the leading edge of the paper discharged from the discharging roll on the upper surface of the paper stacked on the paper discharge tray. As a result, the stacked sheets on the paper discharge tray are pushed out, and the capacity of the paper discharge tray is poor.

  In order to solve the above-described problems, the present invention is characterized by a paper discharge means, a detection means for detecting the paper being conveyed, and at least during paper discharge by the paper discharge means, deviating from the paper discharge trajectory, The paper discharge mechanism includes: a paper push-down means that acts to push down a rear portion of the paper immediately after the paper detected by the detection means is discharged by the paper discharge means. As a result, the rear portion of the paper does not remain on the discharge roll, and the leading edge of the paper is not pushed down by the paper pressing means. Therefore, the leading edge of the paper discharged by the paper discharging means is already stacked on the paper discharge tray. It is possible to prevent the discharged paper from being pushed out and the storage capacity of the paper discharge tray to deteriorate.

  Preferably, the paper discharge means is a paper discharge mechanism composed of discharge rolls arranged on both upper and lower sides with a nip interposed therebetween. Accordingly, it is possible to prevent the rear portion of the paper from remaining on the discharge roll by pushing down the rear portion of the paper by the paper pressing means after the rear end of the paper passes through the nip.

  Preferably, the sheet pressing means is a sheet discharge mechanism configured to act until the sheet rear end passes through the nip and contact with the discharge roll positioned below is released. . As a result, the rear portion of the paper does not remain on the discharge roll, and the leading edge of the paper is not pushed down by the paper pressing means. Therefore, the leading edge of the paper discharged by the paper discharging means is already stacked on the paper discharge tray. It is possible to prevent the discharged paper from being pushed out and the storage capacity of the paper discharge tray to deteriorate.

  Preferably, the detection means is constituted by a detection lever, the paper pressing means is constituted by a paper pressing lever, and the detection lever and the paper pressing lever are connected via a single pivot. The paper discharge mechanism. As a result, the paper pressing lever can be rotated in conjunction with the detection lever, the rear portion of the paper is not left on the discharge roll, and the leading edge of the paper is not pressed down by the paper pressing means. It is possible to prevent the paper already stacked on the paper discharge tray from being pushed out by the leading edge of the paper discharged by the paper discharge means and the storage capacity of the paper discharge tray being deteriorated.

  Preferably, the detection lever and the paper pressing lever are a paper discharge mechanism that rotates downward by its own weight. Accordingly, it is not necessary to separately provide a rotation mechanism for the paper pressing lever, and the force for pressing the rear portion of the paper can be changed by changing the weight of the paper pressing lever.

  Preferably, a spring is attached to the paper pressing lever, and the paper pressing lever is a paper discharge mechanism that rotates downward by the biasing force of the spring. This eliminates the need to worry about the pivot point of the paper pressing lever and the position of the center of gravity as in the case of rotating by its own weight.

  Preferably, the paper pressing lever and the detection lever are formed as an integrated paper discharge mechanism. Thereby, the number of parts in the paper discharge mechanism can be reduced, and the production cost can be kept low.

  Preferably, the paper pressing lever and the detection lever are a paper discharge mechanism that is linked via a link mechanism. As a result, the relative position between the paper pressing lever and the detection lever can be adjusted. Can be changed.

  Preferably, the paper discharge mechanism is provided with a paper discharge sensor that operates in conjunction with the rotation of the detection lever and the paper pressing lever. Accordingly, the paper discharge sensor can be operated by the rotation of the detection lever and the paper pressing lever to control the paper discharge.

  Preferably, the detection unit includes a detection sensor that detects whether or not a rear end of the sheet has passed through the nip of the discharge roll, and the sheet pressing unit includes a solenoid and a sheet driven by the solenoid. A paper discharge mechanism having a pressing lever is provided. As a result, the rear portion of the paper does not remain on the discharge roll, and the front end of the paper is not pushed down by the paper pressing means, so that the paper already loaded on the paper discharge tray is pushed out at the front end of the paper. Therefore, it is possible to prevent the capacity from being deteriorated.

  Preferably, the paper discharge mechanism further includes control means for controlling the solenoid to be driven after a predetermined time has elapsed after the paper is detected by the detection sensor. Accordingly, the operation timing and the number of operations of the rotation lever and the paper pressing lever can be optimized depending on the type of paper, so that the accommodation property can be improved for a wide range of paper.

  Preferably, the paper pressing mechanism is a paper discharge mechanism provided at one or a plurality of locations in the axial direction of the discharge roll. As a result, the capacity can be improved for more types of paper.

  The present invention includes a fixing device that includes the paper discharge mechanism and is detachable from the image forming apparatus main body, and an image forming apparatus that includes the paper discharge mechanism.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention.
The image forming apparatus 10 includes an image forming apparatus main body 12, and an opening / closing door 16 that is rotatable about a rotation fulcrum 14 is provided on the upper portion of the image forming apparatus main body 12.

  For example, a one-stage recording medium supply unit 22 is disposed below the image forming apparatus main body 12. The recording medium supply unit 22 includes a recording medium supply unit main body 23 and a recording medium supply cassette 24 that stores the recording medium. A feed roll 25 for supplying the recording medium from the recording medium supply cassette 24 and a retard roll 26 for scooping the supplied recording medium one by one are arranged in the upper part near the rear end of the recording medium supply cassette 24. In the vicinity of the retard roll 26, a movable member 27 for guiding the recording medium is rotatably provided.

  The conveyance path 28 is a recording medium path from the feed roll 25 to the discharge port 30 formed from the back side of the image forming apparatus main body 12 toward the inside of the image forming apparatus main body 12. The conveyance path 28 is formed substantially vertically from the recording medium supply cassette 22 to a fixing device 90 described later. A secondary transfer roll 80 and a secondary transfer backup roll 72, which will be described later, are arranged on the upstream side of the fixing device 90 in the conveyance path 28, and the resist roll 31 is located on the upstream side of the secondary transfer roll 80 and the secondary transfer backup roll 72. Has been placed. A conveyance roll 32 is provided between the registration roll 31 and the feed roll 25 and the retard roll 26. In addition, a discharge roll 34 composed of an upper roll 34A and a lower roll 34B arranged above and below the discharge port 30 and in the vicinity of the discharge port 30 with a nip 35 interposed therebetween is disposed in the paper discharge unit 33 of the conveyance path 28. Has been. In the vicinity of the discharge roll 34, a detection lever 100 and a sheet pressing lever 102, which will be described later, are arranged around a rotation fulcrum 104.

  Accordingly, the recording medium sent out from the recording medium supply cassette 24 of the recording medium supply unit 22 by the feed roll 25 is wound by the retard roll 26 and only the uppermost recording medium is guided to the conveyance path 28, and between the conveyance rolls 32. The developer image is temporarily stopped by the resist roll 31 and then passed between a secondary transfer roll 80 and a secondary transfer backup roll 72, which will be described later, and the developer image transferred is transferred. The image is fixed by the fixing device 90 and is discharged from the discharge port 30 to the discharge tray 36 provided on the upper portion of the opening / closing door 16 by the discharge roll 34. The discharge tray 36 has a low discharge port 30 and is inclined so as to gradually become higher in the front direction (left direction in FIG. 1).

  In the image forming apparatus main body 12, for example, a rotary developing unit 38 is disposed at a substantially central portion. The rotary developing unit 38 includes developing units 42a to 42d that form developer images of four colors of yellow, yellow, magenta, cyan, and black in the developing unit main body 40, respectively. Rotate counterclockwise about the rotary developer center 44 (counterclockwise in FIG. 1). Each of the developing units 42a to 42d has developing rolls 46a to 46d, and is pressed in the normal direction of the developing unit main body 40 by elastic bodies 48a to 48d such as coil springs. That is, the developing rolls 46a to 46d of the developing units 42a to 42d are arranged on the outer periphery of the developing unit main body 40 at intervals of 90 ° with the rotary developing unit center 44 as the center, and come into contact with an image carrier 50 described later. The electrostatic latent image on the image carrier 50 is visualized with each color developer.

  The image bearing member 50 is disposed in contact with the rotary developing device 38. The image carrier 50 is made of, for example, a tubular aluminum pipe, and a photoconductive layer is formed on the surface thereof. By this photoconductive layer, the image carrier 50 carries an electrostatic latent image formed by a light beam such as a laser beam and a developer image visualized by a developer.

Below the image carrier 50, a charging device 52 made of, for example, a charging roll for uniformly charging the image carrier 50 is provided. Further, an image carrier cleaner 54 is in contact with the image carrier 50 on the upstream side of the charging device 52 in the rotation direction of the image carrier 50. The image carrier cleaner 54 includes, for example, a cleaning blade 56 that scrapes off the developer remaining on the image carrier 50 after primary transfer, and a developer recovery bottle 58 that recovers the developer scraped off by the cleaning blade 56. The
Note that, for example, a rib or the like is formed on the back side (right side in FIG. 1) of the developer recovery bottle 58 and is curved to form a part of the conveyance path 28 so that the recording medium is smoothly conveyed. .

  Below the rotary developing device 38, an exposure device 60 for writing a latent image on the image carrier 50 charged by the charging device 52 by a light beam such as a laser beam is disposed. Further, an intermediate transfer device 62 is provided above the rotary developing device 38. The intermediate transfer device 62 first transfers the developer image visualized by the rotary developing device 38 at the primary transfer position and conveys it to the secondary transfer position.

The intermediate transfer device 62 includes, for example, an intermediate transfer member 64 such as an intermediate transfer belt, a primary transfer roll 66, a wrap-in roll 68, a wrap-out roll 70, a secondary transfer backup roll 72, a scraper backup roll 74, and a brush backup roll 76. Is done. The intermediate transfer body 64 has elasticity, for example, and is stretched substantially flat so as to have a long side and a short side above the rotary developing device 38. The long side on the upper surface side of the intermediate transfer body 64 is stretched so as to be substantially parallel to, for example, the discharge unit 36 provided on the upper portion of the image forming apparatus main body 12. The intermediate transfer member 64 includes a wrap-in roll 68 disposed upstream of the primary transfer roll 66 below the long side of the intermediate transfer member 64, and a wrap-out roll 70 disposed downstream of the primary transfer roll 66. A primary transfer portion (having an image carrier wrap region, is wound around the image carrier 50 by a predetermined range, and is driven by the rotation of the image carrier 50 in this manner. The intermediate transfer body 64 is primarily transferred by the primary transfer roll 66 with the developer image on the image carrier 50 superimposed in the order of, for example, yellow, magenta, cyan, and black, and the primary transferred developer image is subjected to secondary transfer. It is conveyed toward the roll 80.
Note that the wrap-in roll 68 and the wrap-out roll 70 are separated from the image carrier 50.

Further, a flat surface portion (short side) is formed on the back side (right side surface in FIG. 1) of the intermediate transfer body 64 by a wrap-out roll 70 and a secondary transfer backup roll 72, and this flat surface portion is subjected to secondary transfer. It faces the conveyance path 28 as a part.
In the secondary transfer portion, the wrap-out roll 70 is arranged so that the intermediate transfer body 64 and the conveyance path 28 are at an angle of 12 °, for example.

  The scraper backup roll 74 assists the scraper 84 described later to scrape off the developer remaining on the intermediate transfer body 64 after the secondary transfer, and the brush backup roll 76 develops remaining on the intermediate transfer body 64 after the secondary transfer. A brush roll 86 described later assists in scraping off the agent.

  Above the long side of the intermediate transfer body 64, for example, a sensor 78 such as a reflective photosensor is provided by being fixed to the back surface (inside) of the open / close door 16. The sensor 78 reads the developer patch formed on the intermediate transfer body 64, detects the position of the intermediate transfer body 64 in the rotation direction, and detects the developer density.

  A secondary transfer roll 80 is opposed to the secondary transfer backup roll 72 of the intermediate transfer device 62 with the conveyance path 28 interposed therebetween. That is, the secondary transfer position in the secondary transfer portion is between the secondary transfer roll 80 and the secondary transfer backup roll 72, and the secondary transfer roll 80 is intermediate with the assistance of the secondary transfer backup roll 72. The developer image primarily transferred to the transfer body 64 is secondarily transferred to the recording medium at the secondary transfer position. Here, the secondary transfer roll 80 is separated from the intermediate transfer body 64 while the intermediate transfer body 64 rotates three times, that is, while the developer images of three colors of yellow, magenta, and cyan are conveyed. When the developer image is transferred, it is brought into contact with the intermediate transfer member 64.

  In addition, a predetermined potential difference is generated between the secondary transfer roll 80 and the secondary transfer backup roll 72. For example, when the secondary transfer roll 80 is set to a high voltage, the secondary transfer backup 80 The roll 72 is connected to a ground (GND) or the like. That is, the intermediate transfer member 64 is set to a predetermined potential between the secondary transfer roll 80 and the secondary transfer backup roll 72.

  An intermediate transfer member cleaner 82 is provided in contact with the opposite end of the intermediate transfer member 64 on the side opposite to the image carrier. The intermediate transfer member cleaner 82 is, for example, a scraper 84 that scrapes and cleans the developer remaining on the intermediate transfer member 64 after the secondary transfer, a brush roll 86 that scrapes off the developer remaining after cleaning by the scraper 84, and a scraper 84. And a developer recovery bottle 88 that recovers the developer scraped off by the brush roll 86. The scraper 84 is made of, for example, a stainless steel thin plate, and is applied with a voltage having a polarity opposite to that of the developer. The brush roll 86 is made of, for example, an acrylic brush that has been subjected to a conductive treatment. Further, while the intermediate transfer body 64 conveys the developer image, the scraper 84 and the brush roll 86 are separated from the intermediate transfer body 64, and they are integrated with the intermediate transfer body 64 at a predetermined timing. It is supposed to touch.

  A fixing device 90 is disposed above the secondary transfer position. The fixing device 90 includes a heating roll 92 and a pressure roll 94, and fixes the developer image secondarily transferred to the recording medium by the secondary transfer roll 80 and the secondary transfer backup roll 72, and discharges the developer image. Transport toward the roll 34.

  The image forming unit 96 is obtained by integrating the intermediate transfer device 62, the image carrier 50, the charging device 52, the image carrier cleaner 54, and the intermediate transfer member cleaner 82. The image forming unit 96 is disposed immediately below the discharge portion 36 of the opening / closing door 16 and is detachable from the image forming apparatus main body 12, and is attached / detached by opening the opening / closing door 16.

Next, details of the configuration in the vicinity of the discharge roll 34 of the discharge port 30 of the discharge unit 33 according to the first embodiment of the present invention will be described based on the drawings.
FIG. 2 is a cross-sectional view showing the vicinity of the discharge roll 34 of the discharge unit 33 of the first embodiment, and FIG. 3 is a side view seen from the direction of arrow A in FIG.
In the paper discharge unit 33, for example, two discharge rolls (paper discharge means) 34, that is, an upper roll 34 </ b> A and a lower roll 34 </ b> B are arranged on both upper and lower sides across the nip 35, and the paper conveyed to the discharge roll 34. A detection lever (detection means) 100 that rotates by contact and non-contact, and a paper pressing lever (paper pressing means) 102 that rotates in conjunction with the detection lever 100 are connected via a single rotation fulcrum 104. It is connected and provided. In this embodiment, a rear end rotation unit 106 is provided on the opposite side of the rotation lever 104 of the paper pressing lever 102, and the rear end rotation unit 106 is the paper pressing lever 102. As the lens rotates, it rotates up and down. A photo interpreter (sheet discharge sensor) 112 having a light emitting element and a light receiving element is disposed so as to sandwich the rear end rotation portion 106. In the photo interpreter 112, light is emitted from the light emitting element toward the light receiving element, but the optical path is blocked and opened by the rotation of the rear end rotation unit 106, thereby serving as a switch. The control unit 115 controls paper discharge by / OFF.

  The detection lever 100 is disposed on the upstream side of the discharge roll 34 so as to be rotatable around a rotation fulcrum 104 so as to come into contact with the sheet to the position of the nip 35 in the sheet conveyance direction. On the other hand, the sheet pressing lever 102 is out of the sheet discharge locus and is retracted upward with respect to the sheet while the sheet is being discharged by the discharge roll 34 and the sheet is in contact with the detection lever 100. Then, until the rear end of the sheet passes through the nip 35 and the contact with the lower roll 34B is released, that is, immediately after the rear end of the sheet is separated from the detection lever 100, it rotates downward in conjunction with the detection lever 100. The rear portion of the sheet immediately after being discharged from the discharge roll 34 is hit and pushed down. In this embodiment, the detection lever 100 and the paper pressing lever 102 are integrally formed. However, a paper discharge mechanism in which the detection lever 100 and the paper pressing lever 102 are interlocked via a link mechanism. You can also. When a link mechanism is interposed between the detection lever 100 and the paper pressing lever 102, the positions of the detection lever 100 and the paper pressing lever 102 can be adjusted as appropriate.

  Note that the paper pressing lever 102 has a downward-pointing character shape, the center of gravity is provided on the discharge tray 36 side with respect to the rotation fulcrum 104, and the front end 103 is positioned immediately after the discharge roll 34. Is provided. In this way, the detection lever 100 and the paper pressing lever 102 can be rotated by their own weights, and they are provided without separately providing a device for rotating the detection lever 100 and the paper pressing lever 102. It can be rotated. Further, since the paper pressing lever 102 rotates by its own weight, the force for pressing down the rear portion of the paper can be changed by changing the weight of the paper pressing lever 102.

  In this embodiment, the detection lever 100 and the paper pressing lever 102 are rotated by their own weight. For example, a spring is attached to the paper pressing lever 102 so that the paper pressing lever 102 and the detection lever 100 are You may make it rotate with the urging | biasing force of a spring immediately after a rear end leaves | separates from the detection lever 100. FIG. By rotating the paper pressing lever 102 and the detection lever 100 using springs in this way, the position of the fulcrum and the center of gravity for rotating the paper pressing lever 102 is taken care of as it rotates by its own weight. The paper pressing lever 102 can be arranged without the need to do so.

  In this embodiment, the lower roll 34B of the discharge roll 34 is formed of a rubber roll. Thereby, the load from the top with respect to the lower side roll 34B goes up, and the conveyance force of the discharge roll 34 can be improved more.

  In this embodiment, as shown in FIG. 3, the discharge rolls 34 are provided at two positions on the left and right in the axial direction of the rotary shaft 37, and a paper pressing lever 102 as a paper pressing means is provided at one central portion. However, a plurality of paper pressing levers 102 may be provided along the axial direction of the discharge roll 34. As a result, the capacity can be improved for more types of paper.

Next, the operation of the paper discharge unit 33 according to the first embodiment of the present invention will be described with reference to the drawings.
For example, as shown in FIGS. 4A to 4D, the paper is transported in the direction of arrow B, and the detection lever 100 first starts the front end of FIG. 4A due to the friction of the paper as the front end of the paper moves. It rotates in the direction of arrow C from the position where it contacts the detection lever 100, and reaches the same position as the nip 35 of the discharge roll 34 in the sheet discharge direction as shown in FIG. 4B. Thereafter, the sheet passes through the nip 35 of the discharge roll 34, and as shown in FIG. 4C, immediately after the trailing end of the sheet is separated from the detection lever 100, the sheet rotates in the direction of arrow D due to its own weight. 4 (a), the leading edge of the sheet returns to the position where it contacts the detection lever 100 for the first time.

  The paper pressing lever 102 is moved from the position where the paper shown in FIG. 4A is pressed to the arrow C in conjunction with the contact of the paper conveyed to the discharge roll 34 and the rotation of the detection lever 100 in the arrow C direction. It rotates in the direction, that is, upward, and reaches the position deviated from the sheet discharge locus in FIG. Then, while the sheet being discharged by the discharge roll 34 is in contact with the detection lever 100, the sheet is stopped at that position. Thereafter, as shown in FIG. 4C, immediately after the trailing edge of the paper is separated from the detection lever 100 by the discharge roll 34, the paper roll is rotated in the direction of arrow D, that is, downward. Then, as shown in FIG. 4D, the paper pressing lever 102 rotated downward strikes and pushes down the rear part of the paper discharged from the discharge roll 34, thereby storing the paper in the discharge tray 36.

  By doing so, the rear end of the paper does not remain on the lower roll 34B of the discharge roll 34, and the front end of the paper passes under the front end 103 of the paper pressing lever 102 located immediately after the discharge roll 34. At that time, since the sheet is being discharged by the discharge roll 34 and is in contact with the detection lever 100, the sheet pressing lever 102 is removed from the sheet discharge locus and retracted upward. Therefore, it is possible to prevent the paper already loaded on the discharge tray 36 from being pushed out at the front end of the paper discharged from the discharge roll 34 and the storage performance is deteriorated.

Next, details of the configuration of the paper discharge unit 33 according to the second embodiment of the present invention will be described with reference to the drawings.
FIG. 5 is a cross-sectional view showing a state in the vicinity of the discharge roll 34 of the paper discharge unit 33 of the second embodiment.
In the paper discharge unit 33 of this embodiment, a detection sensor 114 is provided on the upstream side of the discharge roll 34 to detect whether or not the rear end of the paper has passed through the nip 35 of the discharge roll 34. A solenoid 116 is provided in which a signal from the detection sensor 114 is sent to the control unit 115 and controlled by the control unit 115. A rotating lever 118 that rotates by driving of the solenoid 116 and the urging force of the spring 120 and a sheet pressing lever 102 having a tip 103 immediately downstream of the discharge roll 34 rotate around the rotating fulcrum 104. It is provided integrally in a movable manner. Specifically, the solenoid 116 has an iron core 117 that slides in the direction away from the discharge roll 34 in FIG. 5, that is, the E direction by driving, and the solenoid 116 is driven to slide the iron core 117 in the E direction. Thus, the turning lever 118 and the paper pressing lever 102 are turned by the biasing force of the spring.

Next, the operation of the paper discharge unit 33 according to the second embodiment of the present invention will be described with reference to the drawings. Normally, as shown in FIG. 6A, the rotating lever 118 is pushed by the iron core 117 of the solenoid 116. In this state, the paper pressing lever 102 is out of the paper discharge path and is in a position retracted from the paper. On the other hand, the detection sensor 114 detects whether the trailing edge of the sheet has passed through the nip 35 of the discharge roll 34, and sends the signal to the control unit 115.

As shown in the flowchart of FIG. 7, the control unit 115 performs initial setting such as resetting a timer, which will be described later, in step 10 (S10). In step 12 (S12), the control unit 115 determines whether the detection sensor detects whether the trailing edge of the sheet has passed through the nip. If the detection sensor detects that the trailing edge of the sheet has passed through the nip, the process proceeds to the next step 14 (S14). If the trailing edge of the sheet does not pass through the nip, the process waits. .
In step 14 (S14), a timer is set. The set time of this timer is the time until the trailing edge of the sheet passes through the nip and the contact with the lower roll 34B is released, and is the optimal time for the sheet pressing lever 102 to depress the rear portion of the sheet. And Next, in step 16 (S16), it is determined whether or not the predetermined time has elapsed. When the predetermined time has elapsed, the process proceeds to step 18 (S18), and when the predetermined time has not elapsed, the apparatus enters a standby state. In step 18 (S18), the solenoid 116 is operated as shown in FIGS. 6B and 6C, and the iron core 117 is slid in the E direction. By rotating the push lever 102, the rear portion of the paper is pushed down and accommodated in the discharge tray 36. Then, after the solenoid 116 is activated in step 20 (S20), the timer is reset, and the process returns to step 12.
As described above, when the control unit 115 performs the above-described processing and the solenoid is driven, the iron core 117 slides in the E direction, and accordingly, the rotation lever 118 and the paper pressing lever 102 move in the direction of the solenoid 116. The rear part of the paper is pushed down by turning.

  As described above, the position of the trailing edge of the sheet is detected by the detection sensor 114, and the control unit 115 sets a time that is optimal for the sheet pressing lever 102 to push down the rear of the sheet. Since the solenoid 116 is driven, the rear part of the paper can be pushed down by the paper pushing lever 102 at an optimal timing. Therefore, the operation timing and the number of operations of the rotation lever 74 and the paper pressing lever 102 can be optimized depending on the type of paper, so that the accommodating property can be improved for a wide range of paper.

  In this embodiment, a spring 120 is attached to the paper pressing lever 102, and the paper pressing lever 102 is rotated by the biasing force of the spring 120 when the solenoid 116 is driven. In this way, the paper pressing lever 102 is rotated by the biasing force of the spring 120, and the driving of the solenoid 116 is stopped and the paper pressing lever 102 returns to the original position. There is no need to install. Also in this embodiment, a plurality of paper pressing levers 102, a rotating lever 118, and a solenoid 116 may be provided along the axial direction of the discharge roll 34, which allows more paper types. The capacity of the paper discharge tray 36 can be improved.

  In this embodiment, the paper pressing lever 102 and the rotation lever 118 are integrally formed, but they may be linked via a link mechanism. In this way, the positions of the paper pressing lever 102 and the rotating lever 118 can be adjusted. In particular, when the paper pressing lever 102 is rotated by its own weight, a force for pressing the rear part of the paper is used. It can be changed.

  As described above, the present invention can be used for a paper discharge mechanism capable of improving the accommodation property without the rear end of the paper remaining on the discharge roll and the image forming apparatus having the paper discharge mechanism.

1 is a cross-sectional view of an image forming apparatus according to a first embodiment of the present invention. It is sectional drawing which shows the outline | summary of the paper discharge mechanism which concerns on the 1st Embodiment of this invention. It is a side view which shows the outline | summary of the paper discharge mechanism which concerns on the 1st Embodiment of this invention. FIG. 6 is a process diagram illustrating a paper discharge process of the paper discharge mechanism according to the first embodiment of the present invention. It is sectional drawing which shows the outline | summary of the paper discharge mechanism which concerns on the 2nd Embodiment of this invention. FIG. 10 is a process diagram illustrating a paper discharge process of a paper discharge mechanism according to a second embodiment of the present invention. 10 is a flowchart of a control unit of a paper discharge mechanism according to a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 33 Paper discharge part 34 Paper discharge roll 34A Upper roll 34B Lower roll 35 Nip 36 Paper discharge tray 37 Rotating shaft 100 Detection lever 102 Paper push lever 103 Tip 104 (paper push lever) Tip 104 Rotation fulcrum 106 Rear End rotating part 112 Photo interpreter 114 Detection sensor 115 Control part 116 Solenoid 118 Turning lever 120 Spring

Claims (14)

  A paper discharge means, a detection means for detecting the paper being transported, and at least during paper discharge by the paper discharge means, the paper is deviated from the paper discharge locus, and the paper detected by the detection means is discharged by the paper discharge means. And a sheet pressing unit that operates to depress the rear portion of the sheet immediately after being discharged.   The paper discharge mechanism according to claim 1, wherein the paper discharge means includes discharge rolls arranged on both upper and lower sides with a nip interposed therebetween.   The paper discharge mechanism according to claim 2, wherein the paper pressing means is configured to act until a rear end of the paper passes through the nip and contact with a discharge roll positioned below is released. .   The detection means is constituted by a detection lever, the paper pressing means is constituted by a paper pressing lever, and the detection lever and the paper pressing lever are connected via a single pivot. Item 4. The paper discharge mechanism according to any one of Items 1 to 3.   The paper discharge mechanism according to claim 4, wherein the detection lever and the paper pressing lever rotate downward by their own weight.   The paper discharge mechanism according to claim 4, wherein a spring is attached to the paper pressing lever, and the paper pressing lever is rotated downward by a biasing force of the spring.   The paper discharge mechanism according to claim 4, wherein the paper pressing lever and the detection lever are integrally formed.   The paper discharge mechanism according to claim 4, wherein the paper pressing lever and the detection lever are linked via a link mechanism.   9. The paper discharge mechanism according to claim 4, further comprising a paper discharge sensor that operates in conjunction with the rotation of the detection lever and the paper pressing lever.   The detection means includes a detection sensor that detects whether or not a rear end of the paper has passed through the nip of the discharge roll, and the paper pressing means includes a solenoid and a paper pressing lever driven by the solenoid. 4. The paper discharge mechanism according to claim 1, further comprising:   11. The paper discharge mechanism according to claim 10, further comprising control means for controlling the solenoid to be driven after a predetermined time has elapsed after detecting the paper by the detection sensor.   The paper discharge mechanism according to any one of claims 1 to 11, wherein the paper pressing means is provided at one or a plurality of locations in the axial direction of the discharge roll.   13. A fixing device comprising the paper discharge mechanism according to claim 1 and detachable from an image forming apparatus main body.   An image forming apparatus comprising the paper discharge mechanism according to claim 1.

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