JP3651993B2 - Refeed apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refeed apparatus and an image forming apparatus, and more specifically, a refeed apparatus that is detachably assembled to an image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, and a laser beam printer, and the like. The present invention relates to an image forming apparatus including
[0002]
[Prior art]
Conventionally, a refeed apparatus assembled in an image forming apparatus such as a laser beam printer switches back the sheet material so that recording can be performed on the other side of the sheet material recorded on one side. Refeeding is performed to the image forming unit of the image forming apparatus main body, and many products have already been commercialized and put into practical use.
[0003]
[Problems to be solved by the invention]
The present invention is a further development of the above-described conventional re-feeding device, and its object is to provide a re-feeding device that is easy to handle for the purpose of cost reduction and noise reduction. is there.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, a representative configuration of the present invention includes a sheet material conveyance path on the downstream side in the sheet material conveyance direction and a sheet on the upstream side in the sheet material conveyance direction of the image forming unit with respect to the image forming unit of the image forming apparatus main body. A refeed conveyance path that communicates with the material conveyance path, and a switch that is disposed in a part of the refeed conveyance path and that receives the sheet material from the carry-out means of the main body of the image forming apparatus and reverses the conveyance direction of the sheet material Back conveying means and refeed means for returning the sheet material to the upstream side in the sheet material conveying direction of the image forming means through a part of the refeed conveying path, and is detachably assembled to the image forming apparatus main body. The refeeding apparatus includes a switchback driving unit for driving the switchback conveying unit, and a refeeding driving unit for driving the refeeding unit, the switchback driving unit and The refeeding drive means, and having a respective separate forward and reverse rotatable drive source, and a switching means for switching the conveying speed of the sheet material by the rotation direction of the driving source.
[0005]
According to the above configuration, the sheet material can be transported at a transport speed faster than the transport speed in the refeed apparatus except when the sheet material is transferred between the image forming apparatus main body and the refeed apparatus. It becomes.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a refeed apparatus to which the present invention is applied and an image forming apparatus including the refeed apparatus will be specifically described with reference to the drawings.
[0007]
[First Embodiment]
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing a schematic configuration of an image forming apparatus provided with a refeed device according to the present embodiment. In this embodiment, a laser beam printer is illustrated as an example of the image forming apparatus. In the following description, first, the configuration of an image forming apparatus provided with a refeed device will be described, and then the operation thereof will be described.
[0008]
(Configuration of image forming apparatus provided with refeed device)
As shown in FIG. 1, the image forming apparatus main body 1 includes a feeding roller 2b that feeds the sheet material S in the sheet feeding cassette 2a one by one, a number of rollers 2c that convey the fed sheet material S, 2d, 2e, 2g, etc., conveying means 2, a scanner unit 3 for irradiating information light based on image information to the electrophotographic photosensitive member 4a of the image forming unit 4, and image formation for forming an image on the electrophotographic photosensitive member 4a A transfer unit 5 for transferring an image formed on the electrophotographic photosensitive member 4a to the sheet material S; a fixing unit 6 for fixing the transferred image to the sheet material S;
[0009]
Usually, the number of output sheets of the image forming apparatus is determined in advance. In the present embodiment, the sheet conveyed by the conveying unit 2 (each roller 2c, 2d, 2e, 2g, etc.), the transfer unit 5, and the fixing unit 6. The conveying speed of the material S is set to be substantially the same speed P.
[0010]
The image forming unit 4 includes an electrophotographic photosensitive member 4a and at least one process unit, and is unitized as a process cartridge that is detachable from the image forming apparatus main body 1. Here, as the process means, for example, a charging means for uniformly charging the surface of the electrophotographic photosensitive member 4a, a developing means for developing a latent image formed on the electrophotographic photosensitive member 4a, and the electrophotographic photosensitive member 4a. There are cleaning means for removing deposits such as waste toner remaining on the surface.
[0011]
In the image forming apparatus main body 1, the sheet material S is again applied to the image forming unit 4 in order to perform recording on the other surface of the sheet material that has already been recorded on one surface (to perform so-called double-sided printing). A re-feeding device 10 for feeding to is detachably attached. As shown in FIG. 16, the refeed device 10 has a portion (gripping portion) protruding from the image forming apparatus main body 1, and the image forming apparatus main body of the refeed device 10 is held by the user. 1 is configured to perform an attaching / detaching operation with respect to 1.
[0012]
The refeed apparatus 10 automatically switches the flapper 9 supported so as to be swingable, and automatically selects the sheet material unloading direction (face-down unloading path / refeed conveying path) on which recording has been performed. Switching means 11 is provided. The automatic switching means 11 includes a switching lever 11a that can swing around a support shaft 11a1, and a plunger (solenoid) 11b that swings the switching lever 11a. A cam follower 11a2 that contacts a cam member 9b fixed to the flapper 9 is formed at one end of the switching lever 11a, and the plunger 11b is coupled to the other end. Further, the flapper 9 is supported so as to be able to swing around a rotating shaft 9a, and is always urged clockwise by an elastic member (not shown).
[0013]
Further, a cover member 12 having a guide surface 12a for introducing the sheet material S carried out from the image forming apparatus main body 1 into the refeed device 10 is arranged near the sheet material carry-in entrance of the refeed device 10. It is installed. In the re-feed conveyance path of the re-feed device 10, the switch-back conveyance roller pair 13 capable of forward / reverse rotation for performing the switch-back conveyance of the sheet material S introduced from the sheet material carry-in port, and this switch A reverse flapper 18 for guiding the leading edge of the sheet material S switched back by the back conveying roller pair 13 is provided. A detection sensor 17 for detecting the position of the reverse flapper 18 is attached in the vicinity of the reverse flapper 18. The switchback conveying roller pair 13 includes a conveying roller 13a that is driven to rotate and a roller 13b that is driven to rotate while being in pressure contact with the conveying roller 13a.
[0014]
A large number of refeed conveyance paths A, B, C, and D are formed in the refeed apparatus 10 by guide members 12, 19a, 19b, 20, 23, and the like. The refeed conveyance path A is formed by the guide surface 12a of the cover member 12 and a curved guide member 19a. The refeed conveyance path B is formed by the guide member 20 and the guide surface 12b of the cover member 12, and guides and stores the sheet material S to be switched back. The refeed conveyance path C is formed by the curved guide member 19a and a guide member 19b which is similarly curved on the inner side. The refeed conveyance path D is formed by a guide member 23 that constitutes a position restricting means (lateral registration restricting means) 22 described later. The configuration of the position restricting means 22 will be described in detail later.
[0015]
Further, on the downstream side of the refeed conveyance path D, detection for detecting the presence or absence of the sheet material in the refeed conveyance path D and temporarily stopping the timing of the refeed sheet material A sensor 25 is arranged. Further, a refeed conveyance path E is formed in the vicinity of the sheet material inlet 2i of the image forming apparatus main body 1 by the guide members 21a and 21b. The refeed conveyance path E is connected to the refeed conveyance path D when the refeed apparatus 10 is assembled to the image forming apparatus main body 1. In FIG. 1, reference numeral 28 denotes a substrate on which a power source, a control circuit and the like are arranged.
[0016]
Here, the configuration of the position restricting means 22 will be described. As shown in FIG. 2, the position restricting means 22 includes a contact portion 23 a that abuts the side edge portion of the sheet material S to restrict the position of the side edge portion of the sheet material S. The member 23 and two sets of skew feeding roller pairs 24 that also serve as a refeeding means for conveying the sheet material S while bringing the side edge of the sheet material S into contact with the contact portion of the guide member 23 are provided. . The two pairs of skew feeding rollers 24 have substantially the same configuration, and are composed of a conveying roller 24c that is driven to rotate and a roller 24g that is driven to rotate while being obliquely pressed against the conveying roller 24c. More specifically, a conveying roller 24c made of a friction member is fixed to one end of a drive shaft 24b rotatably supported by a guide member 23 via a bearing 24a, and a belt pulley 24d is fixed to the other end. A belt 24e that transmits driving is stretched between the pulleys 24d and 24d, and a gear 24f that transmits driving force from the driving motor 27 is fixed to an end of one driving shaft 24b. . As a result, both transport rollers 24c are driven at the same rotational speed. In addition, a roller 24g is disposed at a position opposite to the conveying roller 24c so as to be inclined with respect to the rotation center of the drive shaft 24b. The roller 24g is pressed against the conveying roller 24c by an elastic member 24h and is driven to rotate. So that it is supported.
[0017]
Further, as shown in FIG. 3, the refeeding device 10 includes a switchback driving means 40 for driving a switchback conveying roller pair 13 as a switchback conveying means, and an oblique feeding roller pair 24 as a refeeding means. The refeed driving means 60 for driving is provided. The two drive means 40, 60 each have a drive motor 26, 27 which is a drive source capable of rotating in the forward and reverse directions, and the sheet material transport speed by the roller pair 13, 24 according to the rotation direction of the drive motors 26, 27. There are switching means comprising a pendulum arm 43 and a pendulum gear 44 for switching, and they are attached to both side plates 30a and 30b arranged outside the sheet width of the sheet material (two-dot chain line in FIG. 3).
[0018]
More specifically, the drive motors 26 and 27 that are the drive sources of the drive means 40 and 60 protrude outward from the image forming apparatus main body 1 when the refeed device 10 is assembled to the image forming apparatus main body 1. Are disposed at the positions (the gripping portions shown in FIG. 16), and at positions facing each other with respect to the center in the width direction of the sheet material (two-dot chain line in FIG. 3).
[0019]
Due to the above configuration, the driving means 40 and 60 having a heavy weight are disposed in the vicinity of the portion gripped by the user when the refeed device 10 is attached / detached, so that when the refeed device 10 is attached / detached, Balance is improved and handling becomes easy. Furthermore, since the refeed device 10 is provided with drive motors 26 and 27 that are heating elements at portions protruding from the main body of the image forming apparatus, the temperature rise in the apparatus can be suppressed.
[0020]
Next, the configuration of the switchback driving means 40 and the refeed driving means 60 will be described in detail. As shown in FIG. 4, the switchback drive means 40 includes a drive motor 26 as a drive source, a motor gear 41 fixed to the motor 26, an idler gear 42 meshing with the motor gear 41, and a rotation support of the idler gear 42. The pendulum arm 43 is pivotally supported on a shaft 42a, and the pendulum gear 44 is pivotally supported on an end 43a of the pendulum arm 43 and meshes with the idler gear 42. An elastic portion 43b is formed on a part of the pendulum arm 43, and a protrusion 43c at the tip thereof presses the idler gear 42 with a predetermined pressure. Adjacent to the pendulum gear 44, a step gear 45 and a step gear 46 are arranged at a predetermined interval. The step gear 45 and the step gear 46 are arranged so as to be engaged with the pendulum gear 44 and bite. Further, the step gear 45 and the step gear 46 are connected via an odd number (in this embodiment, one) idler gear 47. Further, the gear 50 fixed to one end of the transport roller 13 a of the switchback transport roller pair 13 and the step gear 46 are connected via an idler gear 51. In the figure, 52 is a retaining ring and 53 is a bearing.
[0021]
That is, as shown in FIGS. 5 and 6, the switchback drive means 40 has two types of drive transmission systems having different reduction ratios (a drive transmission system that is decelerated via the step gear 45 and a step gear 46). When the rotational direction of the drive motor 26 changes, the drive transmission system is switched by the switching means comprising the pendulum arm 43 and the pendulum gear 44, and the switchback conveying roller pair 13 The conveying speed of the sheet material S is changed. Specifically, when switching to a drive transmission system that is decelerated via the step gear 46, the switchback conveyance roller pair 13 is substantially equal to the conveyance speed P of the conveyance means 2 on the image forming apparatus main body 1 side. P ₁ When the sheet material S is transported and switched to a drive transmission system that is decelerated via the step gear 45, the switchback transport roller pair 13 is transported by the transport speed P. ₁ Faster transfer speed P ₂ Is configured to convey the sheet material S. Further, the switchback driving means 40 is configured such that when the rotation direction of the drive motor 26 changes, the rotation direction of the transport roller 13a also changes.
[0022]
As shown in FIG. 7, the refeed driving means 60 is configured in substantially the same manner as the switchback driving means 40. The difference from the switchback drive means 40 is that the step gear 45 and the step gear 46 are connected via an even number (two in this embodiment) of idler gears 61 and 62, and the skew feed roller pair 24 The gear 24f fixed to one end of the conveying roller 24c and the idler gear 62 are connected via idler gears 63 and 64.
[0023]
That is, as shown in FIGS. 8 and 9, the refeed driving means 60 is decelerated by two types of drive transmission systems (a drive transmission system decelerated by the step gear 45 and a step gear 46) having different reduction ratios. When the rotational direction of the drive motor 27 changes, the drive transmission system is switched by the switching means comprising the pendulum arm 43 and the pendulum gear 44, and the sheet material S by the skew feeding roller pair 24 is switched. The conveyance speed is changed. Specifically, when switching to a drive transmission system that is decelerated via the step gear 45, the skew feeding roller pair 24 is equal to the switchback conveying roller pair 13 at the conveying speed P. ₂ When the sheet material S is transported and switched to a drive transmission system that is decelerated via the step gear 46, the skew feeding roller pair 24 is transported substantially equal to the transport speed P of the transport means 2 of the image forming apparatus main body 1. Speed P _Three Is configured to convey the sheet material S. Further, the refeed driving means 60 is configured such that the rotation direction of the transport roller 24c is always the same regardless of the rotation direction of the drive motor 27.
[0024]
Therefore, according to the above configuration, the conveyance speed of the conveying unit 2 of the image forming apparatus main body 1 is other than when the sheet material S is transferred between the image forming apparatus main body 1 and the refeed apparatus 10 in the refeed apparatus 10. It is possible to transport the sheet material S at a faster transport speed, and it is possible to prevent a decrease in throughput during double-sided printing (the throughput here means the number of printed sheets in a predetermined time). The same shall apply hereinafter.)
[0025]
Further, since it is possible to change the speeds of the roller pairs 13 and 24 only by changing the rotation direction of the drive motors 26 and 27, there is no need to greatly change the rotation speed of the drive motors 26 and 27. It is possible to suppress the noise of 27 and to prevent a decrease in torque.
[0026]
(Operation of image forming apparatus equipped with refeed device)
Next, the operation of the image forming apparatus provided with the refeed apparatus having the above-described configuration will be described with reference to FIGS. The image forming apparatus shown in FIG. 1 irradiates information light based on image information from the scanner unit 3 to the electrophotographic photosensitive member 4a, forms a latent image on the electrophotographic photosensitive member 4a, and develops the latent image. Thus, a toner image is formed. In synchronization with the formation of the toner image, the sheet material S is conveyed from the cassette 2a to the image forming unit 4 by the pickup roller 2b, the feeding roller pair 2c, and the registration roller pair 2d, and the electronic material of the image forming unit 4 The toner image formed on the photographic photoreceptor 4 a is transferred to the sheet material S by the transfer means 5. The sheet material S after the image transfer is conveyed to the fixing unit 6 and the transferred toner image is fixed to the sheet material S.
[0027]
The fixed sheet material S is conveyed by a pair of carry-out rollers 2e. At this time, since the flapper 9 is at the solid line position in FIG. 1, the sheet material S is guided to the reverse conveyance path 2f by the flapper 9 (solid line position) and discharged onto the paper discharge tray 7 by the carry-out roller pair 2g.
[0028]
Next, in FIG. 10, when the plunger (solenoid) 11b is sucked in the arrow direction in the figure, the switching lever 11a rotates in the clockwise direction (arrow direction in the figure) about the support shaft 11a1. Then, the cam follower 11a2 at one end of the switching lever 11 presses the cam member 9b fixed to the flapper 9, and the flapper 9 counters the biasing force of an elastic member (not shown) around the rotation shaft 9a (in the counterclockwise direction ( The flapper 9 moves to the position of the broken line in FIG. That is, the conveyance direction of the sheet material S is switched by the operation of the plunger 11b.
[0029]
After the image fixing, the sheet material S conveyed by the pair of carry-out rollers 2e is switched in the conveyance direction by the flapper 9 as described above, and the sheet material S is returned to the refeed device 10 through the sheet material carry-out port 2h of the image forming apparatus main body 1. The sheet material S is carried into the feeding conveyance path A. Then, after passing through the reverse flapper 18 while being guided by the guide surface 12a and the guide member 19a, the sheet material S is nipped and conveyed by the switchback conveyance roller pair 13, and enters the refeed conveyance path B as shown in FIG. It is brought in. At this time, the conveying speed P of the sheet material S conveyed by the switchback conveying roller pair 13 ₁ Is set to be substantially equal to the conveying speed P of the sheet material S conveyed by the conveying means 2.
[0030]
The reversing flapper 18 is swingably supported by the support shaft 18a, and has a contact portion 18b that contacts the sheet material S conveyed by the unloading roller pair 2e, and a leading end of the sheet material S conveyed by switchback. A guide portion 18c for guiding and a flag portion 18d provided at one end of the support shaft 18a are provided.
[0031]
When there is no sheet material S in the refeed conveyance path A, a part of the reverse flapper 18 comes into contact with the contact portion 12c provided on the cover member 12, and the reverse flapper 18 is as shown in FIG. Maintaining posture. Here, when the sheet material S is guided by the contact portion 18b of the reverse flapper 18 and passes through, the reverse flapper 18 rotates counterclockwise about the support shaft 18a as shown in FIG. The 18 flag portions 18d are detached from the detection sensor 17. Thereby, the detection sensor 17 detects that the sheet material S is present in the refeed conveyance path A.
[0032]
Here, the switching operation of the drive transmission system of the switchback drive means 40 will be described with reference to FIGS. When the switchback conveying roller pair 13 sandwiches the sheet material S conveyed by the unloading roller pair 2e and further conveys it into the refeed conveying path C, the gear 41 of the drive motor 26 is shown in FIG. Thus, it rotates in the counterclockwise direction (arrow direction in the figure). At this time, the idler gear 42 rotates in the clockwise direction (arrow direction in the figure), and the friction is applied by the elastic portion 43b of the pendulum arm 43. Therefore, the pendulum arm 43 is also in the clockwise direction (arrow direction in the figure). To turn. Then, the sliding portion 44a of the pendulum gear 44 rotating in the counterclockwise direction comes into contact with the sliding portion 46a of the step gear 46, the distance between the shafts is maintained, and the two gears 44 and 46 are engaged with each other. The driving force is transmitted to the conveying roller 48 through the gear trains 51 and 50 as shown in FIG. Here, since the conveying roller 13a is via the step gear 46, the conveying roller 13a rotates in the clockwise direction (in the direction of the arrow in FIG. 4A) at a predetermined reduction ratio, and the sheet material S is conveyed with the conveying speed P of the conveying means 2. Substantially equal transport speed P ₁ It is conveyed by.
[0033]
Next, in FIG. 12, thereafter, the sheet material S is guided by the guide surface 12b while being conveyed. ₁ When the rear end portion of the reverse flapper 18 passes through the reverse flapper 18, the reverse flapper 18 rotates clockwise about the support shaft 18a, and the flag portion 18d of the reverse flapper 18 moves to the detection sensor 17. Enter again. Based on the detection signal of the detection sensor 17, the drive motor 26 is reversely rotated. At this time, the suction of the plunger (solenoid) 11b has already been released, and the flapper 9 is rotated clockwise (in the direction of the arrow in the figure) about the rotation shaft 9a by the biasing force of an elastic member (not shown). Thus, the sheet material has been moved to the original solid line position in FIG. 1 and is already in a state of guiding the sheet material on which images are formed on both sides to the conveyance path 2f.
[0034]
As shown in FIG. 4B, when the gear 41 of the drive motor 26 rotates in the counterclockwise direction (arrow direction in the figure), the pendulum arm 43 rotates in the counterclockwise direction (arrow direction in the figure). . Then, the pendulum gear 44 that rotates in the clockwise direction is easy to escape from the step gear 46, and the sliding portion 44 a of the pendulum gear 44 comes into contact with the sliding portion 45 a of the step gear 45 away from the step gear 46. The two gears 44 and 45 mesh with each other while maintaining a distance, and the driving force is applied to the conveying roller 13a via the gear trains 47, 46, 51 and 50 as shown in FIG. Communicated. Here, since the conveying roller 13a is via the stepped gear 45, it rotates counterclockwise (in the direction of the arrow in FIG. 4 (b)) at a predetermined reduction ratio, and the sheet material S is conveyed at the conveying speed P. ₁ Faster transfer speed P ₂ It is switched back and conveyed. Thereafter, the sheet material S is guided by the guide portion 18c of the reverse flapper 18 and is carried into the refeed conveyance path C.
[0035]
Here, the gear ratio of the step gear 46 (small gear / large gear) is N ₁ , The gear ratio of small gear 45 (small gear / large gear) is N ₂ If the rotation speed of the drive motor 26 is the same, the conveyance speed P ₁ And P ₂ The speed ratio is P ₁ : P ₂ = N ₁ : N ₂ It becomes. In the present embodiment, the gear ratio of the step gears 46 and 45 is N. ₁ <N ₂ It is set to become. That is, if the rotational speed of the drive motor 26 during forward and reverse rotation is the same, the relationship of the conveyance speed is P ₁ <P ₂ It becomes.
[0036]
Next, in FIG. 13, thereafter, the sheet material S that is switched back and conveyed by the switchback conveyance roller pair 13 is conveyed along the guide members 19a and 19b that constitute the refeed conveyance path C. Then, the leading edge of the sheet material S is carried into the refeed conveyance path D and carried into the position restricting means (lateral registration restricting means) 22 described above. At this time, the sheet material S has the same conveying speed P as the switchback conveying roller pair 13 while the position regulating means 22 regulates the position of the sheet material in the width direction (direction orthogonal to the conveying direction). ₂ It is conveyed by.
[0037]
Here, the switching operation of the drive transmission system of the refeed driving means 60 will be described with reference to FIGS. When the sheet material S conveyed by the switchback conveying roller pair 13 is nipped and conveyed by the skew feeding roller pair 24 having the role of a refeed means, the gear 41 of the drive motor 27 is opposite as shown in FIG. It rotates in the clockwise direction (arrow direction in the figure). At this time, the idler gear 42 rotates in the clockwise direction (arrow direction in the figure), and the pendulum arm 43 rotates in the clockwise direction (arrow direction in the figure) because the elastic part 43b is applied with friction. Then, the sliding portion 44a of the pendulum gear 44 that rotates in the counterclockwise direction comes into contact with the sliding portion 45a of the step gear 45, the distance between the shafts is maintained, and the two gears 44 and 45 are engaged with each other. As shown in FIG. 8, the driving force is transmitted to the conveying roller 24c via the gear trains 62, 63, 64, 24f and the belt 24e. Here, since the conveying roller 24c is via the stepped gear 45, the conveying roller 24c rotates clockwise (in the direction of the arrow in FIG. 7A) at a predetermined reduction ratio, and the sheet material S and the switchback conveying roller pair 13 are rotated. Same transport speed P ₂ It is conveyed by.
[0038]
Next, in FIG. 14, the sheet material S is detected by the rear end portion of the sheet material S being removed from the nip of the switchback conveying roller pair 13 and then the front end portion of the sheet material S reaching the detection sensor 25. Based on the detection signal of the detection sensor 25, the rotation of the drive motors 26 and 27 is temporarily stopped. Then, after a predetermined time has elapsed, the drive motor 27 rotates in the reverse direction, and the gear 41 of the drive motor 27 starts rotating in the direction opposite to the previous rotation direction. At the same time, driving of the drive motor 26 is stopped, and the switchback conveying roller pair 13 that conveys the sheet material S is driven to convey again in preparation for the case where the next sheet material is conveyed from the image forming apparatus main body 1. Waiting to do.
[0039]
As shown in FIG. 7B, when the gear 41 of the drive motor 27 rotates backward in the clockwise direction (arrow direction in the figure), the pendulum arm 43 rotates in the counterclockwise direction (arrow direction in the figure). Then, the pendulum gear 44 that rotates in the clockwise direction can easily escape from the step gear 45, and the sliding portion 44 a of the pendulum gear 44 comes into contact with the sliding portion 46 of the step gear 46 away from the step gear 45. The two gears 44 and 46 mesh with each other while maintaining a distance, and without being separated by the action of biting, the conveying roller 24c is connected via the gear train 61, 62, 63, 64, 24f and the belt 24e as shown in FIG. Drive is transmitted to. Here, since the conveying roller 24c is via the stepped gear 46, it rotates in the clockwise direction (in the direction of the arrow in FIG. 7B) at a predetermined reduction ratio, and the sheet material S is conveyed with the conveying speed P of the conveying means 2. Substantially equal transport speed P _Three It is conveyed by.
[0040]
Here, the gear ratio N of the step gear 46 ₁ And gear ratio N of gear 45 ₂ The relationship is N ₁ <N ₂ Therefore, if the rotation speed of the drive motor 27 during forward and reverse rotation is the same, the relationship of the conveyance speed is P ₂ <P _Three It becomes.
[0041]
Then, the conveying speed P of the pair of skew feeding rollers 24 serving as the refeeding means _Three And the conveying speed P of the conveying means 2 (rollers 2c, 2d, 2e, 2g), the transferring means 5 and the fixing means 6 located on the downstream side thereof are set to be substantially equal to each other. As shown in FIG. 15, the sheet material S conveyed while the position in the width direction is regulated is re-feeding the image forming apparatus main body 1 from the rear surface side opposite to the surface on which recording has already been performed. While being guided by the guide members 21a and 21b, it is transported into the transport path E to the image forming unit 4. Thereafter, the image forming operation described above is performed in the same manner on the sheet material S, an image is recorded and formed on the screen, and the sheet material S is discharged and stacked on the discharge tray 7 by the pair of carry-out rollers 2g.
[0042]
In the present embodiment, the outer diameters of the transport roller 13a and the transport roller 24c are made substantially equal, and the number of teeth of the gears 50, 24f fixed to the rollers 13a, 24c is set to be approximately equal, whereby the drive motor 26, 27 and a driver for driving it can be made common. As a result, the cost can be reduced.
[0043]
Further, after the rear end portion of the sheet material S has removed the carry-out roller pair 2e, the rotation speed of the drive motor 26 is increased to increase the conveyance speed P. ₁ If it is carried into the refeed conveyance path C at a faster conveyance speed, it becomes possible to further increase the throughput.
[0044]
[Other Embodiments]
In the above-described embodiments, the laser beam printer is exemplified as the image forming apparatus. However, the present invention is not limited to this. For example, the image forming apparatus may be another image forming apparatus such as an electrophotographic copying machine, a facsimile machine, or a word processor. Similar effects can be obtained.
[0045]
【The invention's effect】
As described above, according to the present invention, in the refeeding apparatus, except for the time when the sheet material is transferred between the image forming apparatus main body and the refeeding apparatus, it is faster than the conveying speed of the conveying unit of the image forming apparatus main body. The sheet material can be conveyed at a high conveyance speed, and a reduction in throughput during double-sided recording can be prevented.
[0046]
In addition, since it is possible to change the speed of each conveying means only by changing the rotation direction of the driving source of each driving means, it is not necessary to greatly change the number of rotations of the driving source, the noise of the driving source is kept low, and the torque is reduced. Can be prevented.
[0047]
In addition, since each heavy driving means is disposed in the vicinity of the portion gripped by the user when the refeeding device is attached / detached, the balance when the refeeding device is attached / detached is improved and handling is facilitated. It becomes easy. Furthermore, since the refeeding device is provided with a drive source that is a heating element at a portion protruding from the main body of the image forming apparatus, the temperature rise in the apparatus can be suppressed.
[0048]
Further, the respective means are driven by setting the outer diameters of the conveying roller of the switchback conveying means and the conveying roller of the refeed means to be substantially equal, and setting the number of gear teeth fixed to each of the rollers to be substantially equal. The driving source of the driving means and the driver for driving the driving means can be made common, thereby reducing the cost.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a schematic configuration of an image forming apparatus provided with a refeed device to which the present invention is applied.
FIG. 2 is a schematic top view showing a schematic configuration of a position regulating means of the refeed device.
FIG. 3 is a top view illustrating a schematic configuration of an image forming apparatus including the refeed device.
FIG. 4 is an enlarged side view of the main part for explaining the operation of the switchback drive means of the refeed device.
FIG. 5 is a main part enlarged top view for explaining the operation of the switchback driving means of the refeeding device.
FIG. 6 is an enlarged top view of the main part for explaining the operation of the switchback drive means of the refeed device.
FIG. 7 is an enlarged side view of the main part for explaining the operation of the refeed driving means of the refeed apparatus.
FIG. 8 is an enlarged top view of the main part for explaining the operation of the refeed driving means of the refeed apparatus.
FIG. 9 is an enlarged top view of the main part for explaining the operation of the refeed driving means of the refeed apparatus.
FIG. 10 is an enlarged cross-sectional side view of a main part for explaining a sheet material conveying operation of the image forming apparatus including the refeed device.
FIG. 11 is an enlarged side cross-sectional view of a main part for explaining a sheet material conveying operation of the image forming apparatus including the refeed device.
FIG. 12 is an enlarged cross-sectional side view of a main part for explaining a sheet material conveying operation of the image forming apparatus including the refeed device.
FIG. 13 is an enlarged cross-sectional side view of a main part for explaining a sheet material conveying operation of the image forming apparatus including the refeed device.
FIG. 14 is an enlarged cross-sectional side view of a main part for explaining a sheet material conveying operation of the image forming apparatus including the refeed device.
FIG. 15 is an enlarged side cross-sectional view for explaining a sheet material conveying operation of the image forming apparatus including the refeed device.
FIG. 16 is a side view illustrating a state in which the refeed device is mounted on the image forming apparatus main body.
[Explanation of symbols]
A, B, C, D, E ... Refeed conveyance path
1. Image forming apparatus main body
2 ... Conveying means
2a ... cassette
2b ... Pickup roller
2c: Feed roller pair
2d ... Registration roller pair
2e, 2g ... Unloading roller pair
2f ... Reverse transfer path
2h ... Sheet material exit
2i ... Sheet material entrance
3. Scanner unit
4. Image forming unit
4a ... Electrophotographic photosensitive member
5. Transfer means
6. Fixing means
7 ... Output tray
9 ... Flapper
9a ... Rotating shaft
9b ... Cam member
10 ... Refeeding device
11 ... Automatic switching means
11a ... Switching lever
11a1 ... support shaft
11a2… Cam follower
11b ... Plunger
12… Cover material
12a, 12b ... Guide surface
12c ... contact part
13… Switchback transport roller pair
13a ... Conveying roller
13b ... roller
17, 25 ... Detection sensor
18 ... Inverter flapper
18a ... support shaft
18b ... contact part
18c ... Guide part
18d ... Flag part
19a, 19b, 20, 21a, 21b, 23 ... guide members
22 ... Position control means
23 ... Guide material
23a: Abutting part
24 ... Skew roller pair
24a ... Bearing
24b ... Drive shaft
24c ... Conveying roller
24d ... belt pulley
24e ... Belt
24f ... gear
24g ...
24h ... elastic member
26, 27 ... Drive motor
28… Board
30a, 30b ... side plate
40 ... Switchback drive means
41 ... motor gear
42, 47, 51, 61, 62, 63, 64 ... idler gear
42a ... Rotating spindle
43 ... Pendulum arm
43a ... end
43b ... Elastic part
43c ... Projection
44 ... Pendulum gear
44a, 45a, 46a ... sliding parts
45, 46 ... Step gear
50 ... Gear
52 ... retaining ring
53… Bearings
60 ... Refeed driving means

Claims (5)

A refeed conveyance path that communicates the sheet material conveyance path on the downstream side in the sheet material conveyance direction with respect to the image forming means of the image forming apparatus main body and the sheet material conveyance path on the upstream side in the sheet material conveyance direction of the image forming means;
A switchback conveying means that is disposed in a part of the refeed conveying path, receives a sheet material from the conveying means of the image forming apparatus main body, and reverses the conveying direction of the sheet material;
Refeed means for returning the sheet material to the upstream side in the sheet material conveyance direction of the image forming means via a part of the refeed conveyance path;
In the refeeding device that is detachably assembled to the image forming apparatus main body,
A switchback driving means for driving the switchback conveying means;
Re-feed driving means for driving the re-feed means;
Have
The switchback driving means and the refeed driving means each have independent drive sources capable of rotating forward and reverse, and switching means for switching the sheet material conveyance speed according to the rotation direction of the drive source. Refeed device. The driving source of each of the driving means is disposed at a portion protruding from the image forming apparatus main body when the refeed device is assembled to the image forming apparatus main body, and is centered in the width direction orthogonal to the sheet material conveying direction. The refeeding device according to claim 1, wherein each of the refeeding devices is disposed at a substantially opposite position. The switchback conveying means conveys the sheet material at a conveying speed substantially equal to or faster than the conveying speed of the conveying means of the image forming apparatus main body by the switching means of the switchback driving means, and the refeeding means The sheet material is conveyed by the switching means of the refeed driving means at a conveyance speed substantially equal to the conveyance speed of the switchback conveyance means or a conveyance speed substantially equal to the conveyance speed of the conveyance means of the image forming apparatus main body. Item 2. The refeeding device according to Item 1. Each drive means has two types of drive transmission systems with different reduction ratios, and the drive transmission system is switched according to the rotation direction of the drive source by a switching means having a pendulum gear and a pendulum arm. The refeeding device according to claim 1, wherein Conveying means for conveying the sheet material;
Image forming means for recording an image on the sheet material;
The refeeding device according to any one of claims 1 to 4,
An image forming apparatus.

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