JP2006143355A - Contact/release mechanism for roll pair for image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact/release mechanism for a roll pair for an image forming device, capable of greatly reducing impact vibration noise at nipping time while composing the mechanism as a simple and low-cost one. <P>SOLUTION: This device is provided with a drive roll 2 driven to be normally and inversely rotatable, and a contact/release roll 3 to get in contact with the drive roll 2 in a prescribed case to form a contact part. When the contact/release roll 3 transfers from a release state to a contact state to the drive roll 2, contact surface between the drive roll 2 and the contact/release roll 3 for forming the contact part gradually get in contact with each other in the axial direction, with time difference. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a roll pair contacting / separating mechanism used when supplying, transporting, reversing, discharging, etc. a recording sheet in an image forming apparatus such as a copying apparatus, a printer, and a facsimile.

Japanese Patent Laid-Open No. 4-246055

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying apparatus, when a recording sheet on which an image is formed is supplied from a supply unit, conveyed on a conveyance path, or when the conveyance direction of a recording sheet is reversed, A roll pair contact / separation mechanism is employed that ensures a desired pressure contact force by bringing a pair of rolls into contact with each other in a predetermined case when discharging to the outside of the apparatus. That is, a roll pair contact / separation mechanism is used as one technical means in the case where it is necessary to form a pressure contact portion (nip portion) in a predetermined case.

  As an example of this, for example, in a sheet reversing apparatus, it is necessary to switch the recording sheet conveyance path in accordance with the image forming mode in a conveyance path having a branch path. A pairing / separating mechanism is used.

  Specifically, for example, in the double-sided image forming mode, a recording sheet is introduced by pressing (niping) a pair of rolls constituting a sheet reversing device provided in a predetermined conveyance path at a predetermined timing. Then, the roll is rotated in the reverse direction to reverse the conveyance direction of the recording sheet, and is conveyed into the branch conveyance path for double-sided image formation, and image formation is performed again on the recording sheet.

  And regarding the sheet reversing apparatus including such a roll pair contact / separation mechanism, proposals have been made to simplify and compact the apparatus (for example, see Patent Document 1).

  As shown in FIG. 9, the sheet reversing device disclosed in Patent Document 1 conveys the recording sheet P downward using its own weight in the vertical conveyance path 941, and is provided below the conveyance path. After feeding the recording sheet P between the return rolls 945 and 946 which are in a separated state rotating only in one direction to return the recording sheet P upward, the rolls 945 and 946 are brought into pressure contact with each other by an elastic force, and the position of the branch claw 951 is changed to the branch conveyance path. By switching to the 947 side, the recording sheet P is reversely conveyed upward, and the mechanism is simplified and the cost is reduced without swinging or rotating the return roll. is there.

  However, in the nip mechanism of the sheet reversing device disclosed in the above document, the rolls 945 and 946 collide suddenly at the time of the nip, thereby generating vibrations and causing noise. In particular, in recent years, there is a tendency to increase the nip pressure between rolls for transporting cardboard, and as the spring force that generates the nip pressure increases, the impact when the rolls 945 and 946 collide with each other increases. is there.

  This phenomenon is caused by the impact force when the rolls collide, and the vibration propagates to the structure through a path such as support shaft → bearing → frame / chute, etc. The structure becomes a speaker and generates radiated sound. When a solenoid that can be configured simply and inexpensively is used as a drive source for the roll contact / separation mechanism, speed control is difficult, and an impact force is inevitably applied when the mechanism is operated.

  In order to cope with the above-mentioned problem, a method of driving the link mechanism with a motor without using a solenoid can be considered. However, in this case, cost, space, and the like are greatly disadvantageous. In addition, there is a method of sticking a damping material to the chute or the surface of the frame against the radiated sound phenomenon of the structure, but there are also disadvantages such as an increase in cost. Such mechanisms are often used in image forming devices such as feeder nudger rolls, inverter nip release mechanisms, and finisher eject mechanisms, and their impulse noise and vibration are large, which is very problematic for hearing. However, no effective countermeasures have been found.

  Therefore, the present invention has been made in view of the above problems, and it is possible to provide a roll pair for an image forming apparatus that can greatly reduce the collision vibration noise at the time of nip while configuring the mechanism simply and at low cost. An object is to provide a contact / separation mechanism.

  In order to achieve the above object, a roll pair contact / separation mechanism for an image forming apparatus according to the present invention is driven in a forward / reverse rotation manner, and is moved in contact with / separate from the drive roll. And a contact / separation roll that abuts against the drive roll to form a pressure contact portion, and the drive that forms the pressure contact portion when the contact / separation roll shifts from the separated state to the contact state with respect to the drive roll. The contact surface between the roll and the contact / separation roll is formed so as to contact sequentially in the axial direction with a time difference.

  In the roll pair contact / separation mechanism for an image forming apparatus according to the present invention configured as described above, a drive roll that is driven to rotate forward and reverse, and a drive roll that can be moved toward and away from the drive roll. A contact roll that contacts the drive roll to form a pressure contact portion, and the drive roll forms the pressure contact portion when the contact / separation roll shifts from the separated state to the contact state with respect to the drive roll. The contact surface between the roll pair and the contacting / separating roll is formed so as to contact sequentially in the axial direction with a time difference. Therefore, compared to the case where the contact surfaces of the roll pair are contacted simultaneously, the contact between the roll pair (collision) Vibration and noise can be effectively reduced.

  Here, the time difference may be an odd multiple of a unique half period of the roll pair contact / separation mechanism.

  When configured in this way, the time difference when the contact surface between the drive roll and the contact / separation roll sequentially contacts in the axial direction is an odd multiple of the inherent half cycle of the contact / separation mechanism of the roll pair, The phase of the vibration waveform at the time of the contact impact of the roll pairs that sequentially contact each other is reversed and cancel each other, so that vibration and noise associated with the contact impact can be reduced more effectively.

  The contact / separation roll is formed to be rotatable around a support shaft, and is rotatably supported by a rotation shaft provided alongside the support shaft via a support member. In a state where the separating roll and the driving roll are separated from each other, the support shaft of the contacting / separating roll and the rotating shaft may be arranged to be in a twisted position.

  When configured in this manner, the contact / separation roll is formed so as to be rotatable around the support shaft, and is supported rotatably on a rotation shaft provided alongside the support shaft via a support member, In addition, in the state where the contact / separation roll and the drive roll are separated from each other, the support shaft and the rotation shaft of the contact / separation roll are arranged to be in a twisted position. A roll pair contacting / separating mechanism for sequentially contacting the contact surfaces with a time difference in the axial direction can be realized with a simple configuration at low cost.

  Further, a plurality of the contact / separation rolls are provided on a common support shaft, and the common support shaft is supported by the rotating shaft via a plurality of support members in the vicinity of the plurality of contact / separation rolls. Each of the support positions of the common support shaft by the plurality of support members may be different from each other around the rotation shaft.

  When configured in this manner, a plurality of contact / separation rolls are provided on a common support shaft, and the common support shaft is disposed in the vicinity of the plurality of contact / separation rolls via a plurality of support members. Since the support positions of the common support shaft supported by the rotation shaft are different from each other around the rotation shaft, a mechanism for arranging the support shaft and the rotation shaft at a twisted position is provided. This can be realized more easily, and this makes it possible to realize a simple and low-cost roll pair contact / separation mechanism that sequentially forms contact surfaces with a time difference in the axial direction.

  Further, the support shaft of the contact / separation roll may be cantilevered via a support member with respect to the rotation shaft.

  In such a configuration, although it is difficult to precisely control the timing of the collision, the contact surface formed by the drive roll and the contact / separation roll is formed in a time difference with respect to the roll pair that is sequentially formed in the axial direction. The contact / separation mechanism can be realized with a simpler configuration.

  According to the present invention, it is possible to provide a roll pair contact / separation mechanism for an image forming apparatus with a simple configuration at a low cost, which can significantly reduce vibration and noise associated with a collision during nip.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
<Embodiment 1>

  First, a schematic configuration of an image forming apparatus including a roll pair contacting / separating mechanism according to the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention.

  In FIG. 1, an image forming apparatus 10 capable of forming a color image is provided with an image reading unit 26 for reading a document and a document feeding device 27 for feeding the document to the image reading unit 26. The image forming module 21 is disposed inside the apparatus main body 10, the multi-stage sheet supply trays 31 to 34 are disposed below the image forming module 21, and the multi manual feed tray 35 is provided on the side of the apparatus main body 10. Are arranged to be openable and closable.

  The image forming module 21 used in the present embodiment employs, for example, an electrophotographic system, and includes a photosensitive drum 22 that forms and supports each color component toner image, and each color component on the photosensitive drum 22. The toner images are sequentially transferred to the intermediate transfer belt 23 in sequence, and the secondary transfer device 24 secondarily transfers the multi-color component toner image on the intermediate transfer belt 23 onto the recording sheet and guides it to the fixing device 25. Yes. The intermediate transfer belt 23 is circulated and conveyed by being stretched around a plurality of stretching rolls. The secondary transfer device 24 includes a backup roll 241 that stretches the intermediate transfer belt 23 and the backup roll 241. And a transfer roll 242 arranged to face each other. Reference numeral 231 denotes a cleaner for cleaning the intermediate transfer belt 23.

  Here, around the photosensitive drum 22, a charger 221 for charging the photosensitive drum 22, an exposure device 222 such as a laser scanning device for writing an electrostatic latent image on the photosensitive drum 22, and each color component toner are accommodated. A developing device 223 that visualizes the electrostatic latent image on the photosensitive drum 22, a primary transfer device 224 made of, for example, a transfer roll that transfers each color component toner image on the photosensitive drum 22 onto the intermediate transfer belt 23, and Electrophotographic devices such as a cleaner 225 for cleaning residual toner on the photosensitive drum 22 are sequentially disposed.

  Further, in the present embodiment, the image forming apparatus 10 includes a post-processing device 12 that performs predetermined post-processing on a recording sheet on which an image is formed, and a sheet conveyance path 40 from the sheet supply trays 31 to 34. Is a main conveyance path 41 that is directed upward from the opposite side of the post-processing device 12 and passes through the secondary transfer portion and the primary fixing portion of the image forming module 21 to the post-processing device 12 side. A reverse conveyance path 42 that is provided in a substantially Y shape near the exit and conveys the recording sheet by reversing the front and back of the recording sheet, and a recording sheet that is connected in communication with a part of the reverse conveyance path 42 and has the front and back reversed. A return conveyance path 43 that returns to the main conveyance path 41 in front of the image forming module 21 is provided. Here, a registration roll 44 that transports the recording sheet after positioning is provided upstream of the secondary transfer portion of the main transport path 41, and a transport belt 45 that transports to the fixing device 25 is provided downstream of the secondary transfer portion. Each sheet conveyance path 40 is provided with an appropriate number of conveyance rolls 46.

  In the image forming apparatus configured as described above, each color toner image is formed on the photosensitive drum 22 by the image forming module 21, and each color toner image is sequentially primary-transferred onto the intermediate transfer belt 23, and then the sheet supply tray 31. The recording sheet supplied at a predetermined timing from .about.35 is secondarily transferred at a secondary transfer site, and the toner is transferred while the recording sheet is passed between the heating roll and the pressure roll of the fixing device 25. The image is fixed on the recording sheet, and the image is fixedly formed on the recording sheet. Further, if necessary, the post-processing device 12 performs predetermined post-processing such as sorting and stapling of recording sheets on which images are formed.

  Next, an embodiment in which the roll pair contact / separation mechanism according to the present invention is applied to a sheet reversing device in an image forming apparatus will be described with reference to FIG. FIG. 2 is a schematic diagram illustrating a schematic configuration of the sheet inverting device.

  The sheet reversing device 100 according to the present embodiment is used in a double-sided image forming mode or a face-down mode in which the recording sheet is discharged with the front and back sides reversed, and the like. In the sheet conveying path 40 of the image forming apparatus 10, the reverse conveying path 42 is provided (see FIG. 1). Here, as shown in FIG. 2, the reverse conveyance path 42 includes an upstream branch conveyance path (incoming path) 421 that branches from the middle of the upstream conveyance path 411 (a part of the main conveyance path 41), and a downstream side. A downstream branch conveyance path (unloading path) 422 that joins in the middle of the conveyance path 412 (a part of the main conveyance path 41) is connected in a substantially Y shape via a switchback conveyance path 423. A return conveyance path 43 is connected in the middle of the switchback conveyance path 423. The upstream conveyance path 411 and the downstream conveyance path 412 are connected via a direct conveyance path 413 (a part of the main conveyance path 41).

  Further, in the present embodiment, a branch claw 105 for path switching is provided at a connection portion between the direct conveyance path 413 and the upstream branch conveyance path 421, and the connection between the upstream branch conveyance path 421 and the downstream branch conveyance path 422. Further, a branch claw 106 for path switching is provided in the part, and a branch claw 107 for path switching is provided in a connecting part between the switchback transport path 423 and the return transport path 43. Further, a sheet detection sensor (not shown) is provided immediately before the branching portion to the upstream side conveyance path 411, and detects the position of the leading edge or the trailing edge of the sheet. Based on this detection signal, for example, described later. The timing of forward / reverse rotation of the drive roll 2 of the contact / separation mechanism is set.

  The sheet reversing device 100 includes, for example, a pair of reversal inlet rolls 461 (one of the transport rolls 46) disposed in the upstream branch conveyance path 421 and a pair of reversals disposed in the downstream branch conveyance path 422. It is composed of an exit roll 463, a pair of return rolls 465 provided in the return transport path 43, a reverse roll pair composed of a drive roll 2 and a contact / separation roll 3 disposed below the switchback transport path 423, and the like. ing. Here, the reverse inlet roll 461, the reverse outlet roll 463, and the return roll 465 are composed of a drive roll and a driven roll that is in pressure contact with the drive roll, and is rotated in a fixed direction by a drive motor (not shown).

  On the other hand, the reverse roll pair positioned on the downstream side of the switchback conveyance path 423 constitutes a roll pair contact / separation mechanism according to the present invention, and is driven to be connected to a drive source (not shown) so as to be able to rotate forward and reverse. It is composed of a roll 2 and a contact / separation roll 3 which is a driven roll that moves so as to come into contact / separate with the drive roll 2 and abuts with the drive roll 2 in a predetermined case to form a pressure contact portion (nip portion). Has been.

  Here, the drive roll 2 has a support shaft 2s rotatably supported by a bracket (not shown), and the contact / separation roll 3 is rotatably supported by the support shaft 3s via a bearing 3e. . A spring S is disposed between the outer peripheral portion of the bearing 3e and the support fitting 4 provided on the side wall of the switchback conveying path 423 so as to wind the bearing 3e. 3 is urged to contact the drive roll 2.

  In the sheet reversing apparatus 100 configured as described above, for example, when executing the face-down mode or the double-sided image forming mode, the recording sheet is introduced to the reversing roll pairs 2 and 3 by the branching claws 105 and 106. The direction of the recording sheet is reversed by the reversing roll pairs 2 and 3 and is introduced into the downstream branch conveyance path 422 according to the switching direction of the branch claw 107 (when the branch claw 107 moves to the left side in the figure). The image surface is discharged downward (face-down mode) or introduced into the return conveyance path 43 (when the branching claw 107 moves to the right side in the drawing), and then image formation is also performed on the opposite surface of the recording sheet. Is performed (double-sided image forming mode).

  Next, details of the contact / separation mechanism of the roll pair according to the present invention will be further described with reference to FIG. Here, FIG. 3 is a perspective view showing a configuration of the contact / separation mechanism of the roll pair according to the present invention.

  As shown in FIG. 3 (a), a roll pair contact / separation mechanism 1 according to the present invention is connected to a drive source (not shown) and is configured to be rotatable forward and backward, Drive rolls 2a and 2b that are provided at both ends of the drive-side rotary shaft 2s and are formed so as to be rotatable forward and backward integrally with the rotary shaft 2s, and a support shaft that is disposed so as to face the drive-side rotary shaft 2s. It is rotatably provided at both ends of 3s, and includes drive rolls 2a and 2b and contact and separation rolls 3a and 3b that form nip portions.

  Then, as viewed from the support shaft 3s, a contact-side rotation shaft 5 is provided on the opposite side of the drive-side rotation shaft 2s, and the support shaft 3s is provided in the vicinity of the contact / separation rolls 3a and 3b. It is supported on the contact / separation side rotation shaft 5 via the support members 5a and 5b. A lever-shaped link member 7a is connected to one end of the contact / separation-side rotation shaft 5, and a V-shaped link member is formed via a link groove formed in the base end portion of the link member 7a. 7b is further connected. One end of the link member 7b is connected to a solenoid mechanism. By turning the solenoid mechanism ON / OFF, the support shaft 3s that supports the contact / separation rolls 3a, 3b is a predetermined around the contact / separation-side rotation shaft 5. The contact rolls 3a and 3b at both ends are moved so as to be able to contact and separate from the drive rolls 2a and 2b. Specifically, in the figure, when the solenoid SD is driven by electromagnetic force and moves linearly in the direction of the arrow A, for example, the link member 7b connected thereto rotates in the direction of the arrow B. By rotating in the direction of arrow C, the contact / separation side rotation shaft 5 and the support members 5a and 5b rotate in the direction of arrow D, and the support shaft 3s supported at the tips of the support members 5a and 5b is spring S (FIG. 2). The contact / separation rolls 3a and 3b provided at both ends of the support shaft 3s are moved relative to the drive rolls 2a and 2b by rotating in the direction of arrow E against a biasing force of Move away.

  Here, as shown in FIG. 3B, the support position where the claw portions 5u, 5w at the tips of the support members 5a, 5b support the contact / separation rolls 3a, 3b is the axis of the contact / separation side rotation shaft 5. Around the center 5o, they are set to be different (in the figure, the height with respect to the axis center 5o is different). That is, when the contact / separation rolls 3a, 3b are separated from the drive rolls 2a, 2b as described above, the support shaft 3s of the contact / separation rolls 3a, 3b is a predetermined track around the contact / separation-side rotation shaft 5. And the support shaft 3s of the contact / separation rolls 3a, 3b and the contact shafts 3s, 3b are in contact with the drive rolls 2a, 2b. The dislocation side rotation shaft 5 is not parallel but has a torsional position (the amount of twisting of the support shaft 3s with respect to the contact / separation side rotation shaft 5 is different at both ends in the axial direction). .

  Next, when the solenoid SD is turned off from such a separated state, the electromagnetic force separating the contact / separation rolls 3a, 3b from the drive rolls 2a, 2b is released, and the contact / separation rolls 3a, 3b Due to the elastic force of the spring S (see FIG. 2) urged to come into contact with 2b, the spring S suddenly moves along a predetermined trajectory around the contact / separation side rotation shaft 5 and collides with the drive rolls 2a and 2b. To do. That is, the contact / separation rolls 3a and 3b and the drive rolls 2a and 2b come into impact contact with each other by releasing the electromagnetic force of the solenoid SD.

  Conventionally, vibration and noise associated with such impact contact have been a problem. However, in the case of the contact / separation mechanism 1 of the roll pair according to the present invention, the support shaft 3s and the contact / separation side rotation in the separated state. Since the moving shaft 5 is disposed at the twisted position, the electromagnetic force of the solenoid SD is released from this state, and the contact / separation rolls 3a, 3b are brought into contact with the driving rolls 2a, 2b by the elastic force of the spring S. Even if it moves impactively so as to come into contact, the plurality of contact / separation rolls 3a, 3b do not collide simultaneously with the opposing drive rolls 2a, 2b, and the contact / separation rolls 3a, 3b form a plurality of pairs of nip portions. And the driving rolls 2a and 2b sequentially contact each other in the axial direction with a time difference.

  Specifically, in the case of this example, the contacting / separating roll 3a comes into contact with the driving roll 2a first, and then the contacting / separating roll 3b comes into contact with the driving roll 2b.

  The time difference between the contact timings is determined by the shape of the claw portions 5u and 5w at the tips of the support members 5a and 5b (the claw portions 5u and 5w of the support members 5a and 5b viewed from the rotation center 5o support the support shaft 3s. By appropriately changing the (supporting position), it is possible to sequentially contact at an arbitrary timing.

  In general, there are nonlinear components such as bearing play everywhere in the structure of an image forming apparatus, and the structure does not respond linearly to a certain excitation force (input), but responds in a higher order function. Will be. For this reason, it is possible to suppress the response by applying this force in a distributed manner, rather than applying a large excitation force at a time.

  Therefore, as described above, the drive rolls 2a and 2b forming the nip portion and the contact / separation rolls 3a and 3b are sequentially contacted in a distributed manner to reduce vibration and noise at the time of the collision between the roll pairs 2 and 3. Can do.

  In addition, the time difference of the collision can be set at an arbitrary timing, but the natural frequency of the structure including the contact / separation mechanism of the roll pair such as the roll, the shaft, the bearing, and the frame affected by the collision is grasped, It is preferable to cause the collision at an odd multiple of a specific half period (several tens of ms) obtained from the natural frequency.

  Next, using the roll pair contact / separation mechanism according to the present invention, the results of measurement of time-noise level at the time of collision between the contact / separation roll and the drive roll (when the nip portion is formed) compared with the conventional contact / separation mechanism Will be described with reference to FIGS. Here, FIG. 5 (a) is a diagram showing a time noise level waveform and a time noise sound pressure waveform when a conventional contact / separation mechanism is used, and FIG. 5 (b) shows a roll pair according to the present invention. It is a figure which shows the time noise level waveform and time noise sound pressure waveform at the time of using this contact / separation mechanism. FIG. 6 is a diagram schematically showing a temporal vibration waveform in the case of collision with a time difference that is an odd multiple of the natural half cycle.

  As shown in FIG. 5 (a), in the conventional contact / separation mechanism in which the pair of rolls forming the nip portion are simultaneously contacted in the axial direction, the impact sound at the time of collision is a high noise that significantly exceeds the steady noise. It reaches the level and generates annoying impact noise. Furthermore, the impact noise waveform is affected by the time constant of the structure, and its level does not drop suddenly even after a collision. Therefore, noise exceeding the steady noise level is sustained to some extent.

  On the other hand, when the contact / separation mechanism of the roll pair according to the present invention is used, as shown in FIG. 5B, first, the impact noise level at the first collision is reduced to the steady noise level. Further, it is understood that the impact noise level is reduced to a steady noise level or lower in the second collision. That is, only by shifting the timing of the collision in the axial direction, the noise level associated with the roll pair collision is suppressed to be substantially equal to the steady noise level. There will be almost no noise.

  Further, as shown in FIG. 6, when the second collision is performed after the first collision with a time difference that is an odd multiple of the inherent half cycle, the phase of the second shock vibration wave is reversed. In addition, the shock vibration wave caused by the first collision can be canceled out by the second shock vibration wave, and further noise and vibration suppression effects can be obtained.

  As a modification, the claw portions 5u and 5w of the support members 5a and 5b that support the support shaft 3s are formed of elastic members, and the materials of the claw portions 5u and 5w are changed so that the respective elastic amounts are different. The claw portions 5u and 5w in the separated state may be configured to have different deflection amounts (deformation amounts) when supporting the support shaft 3s.

  Even in such a configuration, when the contact / separation rolls 3a, 3b are separated from the drive rolls 2a, 2b, the support shaft 3s and the contact / separation-side rotation shaft 5 are arranged at the twisted position. The same actions and effects as in the embodiment can be obtained.

In the present embodiment, the case where both the drive roll 2 and the contact / separation roll 3 are installed at two positions on both ends of the support shaft has been described for the sake of simplicity. However, the number of installation is not limited to two. However, the present invention can be applied even when more roll pairs are installed or when one roll-shaped roll pair is installed. For example, when more roll pairs are installed, the corresponding roll pairs may be configured to contact each other sequentially with a time difference, and when one roll-shaped roll pair is installed. May be configured to contact from one end of the roll and to contact the other end at the next timing. As a result, as described above, the impact noise and vibration can be suppressed by dispersing the impact at the time of collision, and moreover, by making the predetermined time difference an odd multiple of the inherent half cycle, the impact noise and vibration can be further increased. Can be obtained.
<Embodiment 2>

  Next, a second embodiment of the roll pair contacting / separating mechanism according to the present invention will be described with reference to FIG.

  The roll pair contact / separation mechanism in the present embodiment is obtained by changing the support member of the support shaft 3 s in the roll pair contact / separation mechanism in the previous embodiment. Reference numerals are assigned and detailed description thereof is omitted.

  As shown in FIG. 4, the contact / separation mechanism 1A for the roll pair according to the present embodiment includes a connection support member 5e for connecting / supporting the contact / separation rolls 3a, 3b with respect to the contact / separation-side rotation shaft 5. The support shaft 3s is provided at the end of the contact / separation roll 3a side, and the support shaft 3s is cantilevered with respect to the contact / separation-side rotation shaft 5.

  Further, a predetermined play is formed between the connection portion 5c of the connection support member 5e and the support shaft 3s, and the support shaft 3s is rotated on the contact and separation side by the connection support member 5e having such play. By supporting the shaft 5 in a cantilever manner, as in the previous embodiment, when the drive rolls 2a, 2b and the contact / separation rolls 3a, 3b are separated from each other, the support shaft 3s is rotated on the contact / separation side. From this state, for example, the support shaft 3s released by the solenoid OFF operation rotates along a predetermined path around the contact / separation-side rotation shaft 5, and the support shaft 3s is moved to the twisted position. For example, the contact / separation rolls 3a and 3b provided at both ends of the contact / separation roll 3a provided on the connection support member 5e side first collide with the drive roll 2a, and then the contact / separation roll 3b on the opposite side The corresponding drive roll 2b with a time difference By collision, it is possible to obtain the same effect as the above embodiment.

  In such a configuration, precise control of the timing of the collision becomes difficult, but the contact / separation mechanism that sequentially contacts the contact surfaces when the roll pair contacts with each other with a time difference in the axial direction is simplified. Can be realized.

  In the above embodiment, the sheet reversing device has been described as an application example of the roll pair contact / separation mechanism according to the present invention. However, the present invention is limited to application to such a sheet reversing device. Instead, it is naturally possible to apply to other devices constituting the image forming apparatus.

An example in which the roll pair contacting / separating mechanism according to the present invention is applied to other components will be described below as third and fourth embodiments.
<Embodiment 3>

  In this embodiment, the roll pair contact / separation mechanism according to the present invention is applied to a post-processing apparatus (see FIG. 1) of an image forming apparatus.

  In FIG. 1, the post-processing apparatus 12 according to the present embodiment is provided with an upper discharge tray 51 and a lower discharge tray 52 in the vicinity of the upper part and the center of the side part, and a conveyance path that communicates with the sheet discharge port from the apparatus main body 20 side. 60, the transport path 60 includes a first transport path 61 that leads to the upper discharge tray 51, and a second transport path 62 that branches from the first transport path 61 and leads to the lower discharge tray 52, A post-processing unit 200 is provided between the second conveyance path 62 and the lower discharge tray 52. Reference numeral 63 is a transport roll, 64 is a discharge roll for discharging the sheet to the upper discharge tray 51, and 65 is a discharge roll for discharging the sheet from the second transport path 62 to the post-processing unit 200.

  In the present embodiment, the post-processing unit 200 includes a post-processing tray 201 that positions and accommodates a plurality of stacked sheet bundles, and a stapler that performs post-processing such as stapling on the sheet bundles in the post-processing tray 201. And a discharge roll 203 for discharging the sheet bundle to the lower discharge tray 52 is provided at the outlet of the post-processing tray 201. Here, the discharge roll 203 includes a drive roll 204 that can rotate in the forward and reverse directions, and a contact / separation roll 205 that is contactable / separable with the drive roll 204 and that rotates following contact.

  In such a post-processing unit 200, for example, in the process in which the recording sheet is accommodated in the post-processing tray 201, the contact / separation roll 205 of the discharge roll 203 is disposed away from the drive roll 204, and the discharge roll 65 The recording sheet discharged from is dropped when the rear end of the sheet is separated from the discharge roll 65 and is stored in the post-processing tray 201. Thereafter, when post-processing by the post-processing unit 202 is performed, the discharge roll 203 is set in a nip state, and the post-processed sheet bundle on the post-processing tray 201 is discharged to the lower discharge tray 52 side by the discharge roll 203. Is done.

  Therefore, by applying the roll pair contacting / separating mechanism 1 according to the present invention to the discharge roll 203 described above, the same effects as those of the previous embodiment can be obtained.

  Specifically, as shown in FIG. 7A, the contact / separation mechanism of the roll pair according to the present embodiment has an approach / separation roll 205 disposed so as to face the drive roll 204. By connecting 205 to a cam mechanism 208 driven by a drive shaft 210 via a link member 206, the contact / separation roll 205 is configured to move so as to be able to contact / separate with respect to the drive roll 204.

  As shown in FIG. 7B, the contact / separation roll 205 is rotatably attached to two locations (205a, 205b) in the vicinity of both ends of the support shaft 205s, and both ends of the support shaft 205s. The part is supported by the through holes 205d and 205f of the bracket. Further, as shown in FIG. 7 (c), the through hole 205d on the contact / separation roll 205a side is formed in a round hole, whereas on the contact / separation roll 205b side as shown in FIG. 7 (d). The through hole 205f is a long hole. In the vicinity of the contact / separation rolls 205a and 205b, compression springs S1 and S2 are attached to the support shaft 205s between the frame and the contact / separation rolls 205a and 205b are always in contact with the drive roll 204. It is so energized.

  In such a configuration, the contact / separation rolls 205a and 205b are separated from the drive roll 204 along with the predetermined rotation of the cam 208, and in this state, the support shaft 205s and the drive shaft 210 are held at the twisted position. The When the cam 208 further rotates, the holding force that holds the contact / separation roll in a predetermined position is released, and the contact / separation rolls 205a, 205b are connected to the drive roll 204 based on the urging force of the compression springs S1, S2. Move in the direction of contact. In the case of this example, after the contact / separation roll 205a contacts the drive roll 204 first, the contact / separation roll 205b contacts the drive roll 204, and the same effect as in the first embodiment can be obtained. Can do.

In the present embodiment, the roll pair contacting / separating mechanism according to the present invention is applied to the discharge roll 203 of the post-processing apparatus 12, but a similar mechanism may be applied to the sheet feeding roll of the sheet feeding apparatus. It is.
<Embodiment 4>

  In the present embodiment, the contact / separation mechanism of the roll pair according to the present invention is applied to the contact / separation mechanism of the transfer roll (see FIG. 1).

  For example, in the case of the image forming apparatus as shown in FIG. 1, while the toner images of the respective colors are primarily transferred to the intermediate transfer belt 23, the transfer roll 242 is separated from the intermediate transfer belt 23 and the intermediate transfer belt 23. After the predetermined primary transfer to the recording medium is completed, it is necessary to move the transfer roll 242 so as to come into contact with the backup roll 241 via the intermediate transfer belt 23 and perform the secondary transfer collectively on the recording sheet.

  Specifically, as shown in FIG. 8, a transfer roll 242 having a roll pair contact / separation mechanism according to the present invention has cams 247a and 247b connected to both ends of a rotating shaft 245, and this cam 247a. , 247b is provided with a cam lever 250 having a pressure receiving member 250p that contacts the peripheral surfaces of the cams 247a, 247b in a predetermined case. The lower end of the cam lever 250 is connected to the frame via a spring S3, and a transfer roll 242 provided at the tip of the cam lever 250 is interposed via the intermediate transfer belt 23 by the elastic force of the spring S3. It is urged to come into contact with the backup roll 241.

  The shapes of the cams 247a and 247b provided at both ends of the rotating shaft 245 are different from each other. When the transfer roll 242 moves away from the backup roll 241, as in the previous embodiment, The shapes of the cams 247a and 247b at both ends of the rotation shaft 245 are set so that the rotation shaft 245 and the support shaft 242s of the transfer roll 242 are in a twisted position.

  In this way, cams 247a and 247b having different shapes are provided at the end of the rotating shaft 245, and the transfer roll 242 is movably supported so as to come into contact with the backup roll 241 via the intermediate transfer belt 23. The contact surfaces of the roll 242 and the backup roll 241 can be configured to sequentially contact in the axial direction, thereby reducing vibration and noise associated with the impact contact of the roll pair via the intermediate transfer belt 23. be able to.

  In the present embodiment, cams 247a and 247b having different shapes are provided at both ends of the rotating shaft 245. However, as in the second embodiment, only one end of the rotating shaft 245 is provided. A cam may be provided so that the contact / separation roll 242 is cantilevered with respect to the rotation shaft.

  Further, since the contact of the roll pair via the intermediate transfer belt 23 can occur in the fixing device as well, a similar mechanism may be applied to the pressure roll of the fixing device.

1 is a diagram illustrating a schematic configuration of an image forming apparatus to which a roll pair contact / separation mechanism according to the present invention is applied. It is a schematic block diagram which shows the outline | summary of the sheet inversion apparatus to which the contact / separation mechanism of the roll pair which concerns on this invention is applied. It is a schematic block diagram which shows the contact / separation mechanism of the roll pair which concerns on Embodiment 1 of this invention. It is a schematic block diagram which shows the contacting / separating mechanism of the roll pair which concerns on Embodiment 2 of this invention. It is a figure which shows the measurement result of the noise level at the time of a roll collision in the conventional contact mechanism of a roll pair, and the contact mechanism of a roll pair which concerns on this invention. It is a figure which shows typically a vibration waveform when the timing of the collision of the roll pair in the contact / separation mechanism of the roll pair which concerns on this invention is made into the odd multiple of a specific half cycle. It is a figure which shows typically the example which applied the contact / separation mechanism of the roll pair which concerns on this invention to the discharge roll of a post-processing apparatus. It is a figure which shows typically the example which applied the contact / separation mechanism of the roll pair which concerns on this invention to the transfer roll. It is a figure explaining the contacting / separating mechanism of the roll pair in the conventional sheet reversing apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 1a: Roll pair contact / separation mechanism, 2a, 2b: Drive roll, 2s: Drive side rotation shaft, 3a, 3b: Contact / separation roll, 3s: Support shaft, 4: Support metal fitting, 5: Contact / separation side rotation Axis, 5a, 5b: support member, 5c: connection portion, 5e: connection support member, 5o: rotation center, 5u, 5w: claw portion, 7a, 7b: link member, 10: image forming device, 12: post-processing device , 21: image forming module, 22: photosensitive drum, 23: intermediate transfer belt, 24: secondary transfer device, 25: fixing device, 31-35: sheet supply tray, 40: sheet conveyance path, 41: main conveyance path 42: reverse conveying path, 100: sheet reversing device, 105, 106, 107: branch claw, 200: post-processing unit, 202: post-processing unit, 203: discharge roll, 204: drive roll, 205a, 205b: contact / separation Roll, 205d, 20 5f: Through hole, 205s: Support shaft, 206: Link member, 208: Cam, 210: Drive shaft, 221: Charger, 222: Exposure device, 223: Development device, 224: Primary transfer device, 225: Cleaner, 241 : Backup roll, 242: transfer roll, 242s: support shaft, 245: rotation shaft, 247: cam, 250: cam lever, 250p: pressure receiving member, 411: upstream side transport path, 412: downstream side transport path, 413: direct transport 421: upstream branch conveyance path, 422: downstream branch conveyance path, 423: switchback conveyance path, 461: reverse entry roll, 463: reverse exit roll, 465: return roll, 941: vertical conveyance path, 945, 946: Roll pair, 951: Branch claw, S: Spring, SD: Solenoid

Claims (5)

A drive roll that is driven to rotate forward and reverse, and a contact roll that moves in contact with and away from the drive roll and forms a pressure contact portion in contact with the drive roll in a predetermined case,
When the contact / separation roll moves from the separated state to the contact state with respect to the drive roll, the contact surfaces of the drive roll and the contact / separation roll forming the press contact portion sequentially contact in the axial direction with a time difference. A roll pair contact / separation mechanism for an image forming apparatus.   2. The roll pair contact / separation mechanism for an image forming apparatus according to claim 1, wherein the time difference is an odd multiple of a unique half cycle of the roll pair contact / separation mechanism.   The contact / separation roll is formed so as to be rotatable around a support shaft, and is rotatably supported by a rotation shaft provided alongside the support shaft via a support member, and the contact / separation roll The support shaft of the said contact / separation roll and the said rotating shaft are mutually arrange | positioned so that it may become a twist position in the state which is spaced apart from the drive roll. Roll pair contact / separation mechanism for image forming apparatus. A plurality of the contact / separation rolls are provided on a common support shaft, and the common support shaft is supported by the rotating shaft via a plurality of support members in the vicinity of the plurality of contact / separation rolls. And
4. The contact / separation mechanism for a roll pair for an image forming apparatus according to claim 3, wherein each of the support positions of the common support shaft by the plurality of support members is different around the rotation shaft.   4. The contact / separation mechanism for a roll pair for an image forming apparatus according to claim 3, wherein the support shaft of the contact / separation roll is cantilevered via a support member with respect to the rotation shaft. .

Images