JP3844184B2 - Paper transport device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus that has a function of conveying a sheet of recording paper, a document, and the like and adjusting the disturbance of the sheet, and an image forming apparatus such as a copying machine, a printer, and a facsimile machine having the sheet conveying apparatus.
[0002]
[Prior art]
For example, in an image forming apparatus such as a copying machine, a printer, or a facsimile machine, a paper conveying device aligns misalignment during paper conveyance, and after alignment, conveys the paper to a transfer nip portion between a photoconductor and a transfer roller at a predetermined timing. It is like that. In other words, the position deviation of the paper is corrected near the image transfer area to prevent the transfer position deviation.
The sheet conveying device includes a sheet feeding unit that feeds sheets stacked on a sheet feeding tray or sheet feeding table one by one, a pair of conveying rollers provided on the downstream side of the sheet feeding direction in the sheet conveying direction, and the pair of conveying rollers. of having a provided we resist roller pair in the paper conveying direction downstream side, the nip portion of the registration roller pair in a state of abutting the leading edge of the sheet to form a deflection at the tip portion of the sheet, the posture shift of the paper After the alignment, the pair of registration rollers are conveyed to a transfer nip portion as the next section at a predetermined timing.
[0003]
Even after the leading edge of the sheet passes through the pair of conveying rollers and reaches the pair of registration rollers, the pair of conveying rollers is driven for a predetermined time, and due to this overfeed, the sheet is bent between the pair of registration rollers and the pair of conveying rollers. . The leading edge of the paper is abutted against the nip portion of the registration roller pair by the elastic force (flexing force) caused by the bending, and the deviation of the posture of the paper is corrected by the leading edge of the paper along the nip line.
The conveyance roller pair is stopped after being driven for a predetermined time, and after forming the deflection, the registration roller pair is re-driven and the conveyance of the sheet is restarted.
The conveyance roller pair is driven / stopped via a clutch, and no load is applied to the conveyance roller pair when stopped. Accordingly, the conveyance roller pair at the time of stopping can be rotated either forward or reverse, and even if a paper jam occurs in the vicinity of the conveyance roller pair, no load is applied to the paper. It can be taken out in either the upstream or downstream direction.
In other words, the paper jam handling performance near the pair of conveyance rollers is emphasized.
[0004]
[Problems to be solved by the invention]
However, since the conveyance roller pair can be rotated forward / reversely, at the moment when the sheet is bent between the registration roller pair and the conveyance roller pair, the conveyance roller pair is rotated in reverse by the bending force. The paper flowed back to the upstream side in the conveyance direction, and bending occurred between the conveyance roller pair and the paper feeding means.
In this state, when the registration roller pair is driven again to transport the paper to the next section, the flexure formed between the transport roller pair and the paper feeding means is urged and the squealing sound (the loose paper is suddenly stretched). Noise caused by noise) was a problem.
[0005]
Accordingly, the present invention provides a sheet conveying apparatus that can reduce noise caused by a squeezing noise while maintaining the paper jam handling performance in the vicinity of the pair of conveying rollers, and can contribute to noise reduction in an office or the like, and an image forming apparatus having the sheet conveying apparatus. Is its main purpose.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a sheet feeding unit that feeds stacked sheets one by one, a pair of conveyance rollers provided on the downstream side of the sheet conveyance direction of the sheet feeding unit, It has provided we resist roller pair in the paper conveying direction downstream side of the transport roller pair, to form a deflection at the tip portion of the sheet in a state of abutting the leading edge of the sheet to the nip portion of the registration roller pair, the sheet A one-way clutch that allows only the forward rotation of the pair of conveying rollers to convey the sheet in the sheet conveying direction in the sheet conveying apparatus that conveys the sheet to the next section at a predetermined timing by the registration roller pair after aligning the posture deviation. together have, have a declutching means allowing forward / reverse rotation of the conveying roller pair, said declutching means, the one-way clutch is rotatably supported A rotating member for holding the clutch pawls has an operating member for turning the the pivoting member, and employs a configuration that.
[0007]
According to the invention of claim 2, a sheet feeding unit that feeds the stacked sheets one by one, a pair of conveying rollers provided on the downstream side of the sheet conveying direction of the sheet feeding unit, and a downstream of the conveying roller pair in the sheet conveying direction. The registration roller is provided with a pair of registration rollers provided on the side, and forming a deflection at the leading end of the sheet in a state where the leading end of the sheet is abutted against the nip portion of the registration roller pair, and aligning the positional deviation of the sheet. In the sheet conveying apparatus that conveys the sheet to the next section at a predetermined timing by the pair , the conveyance roller pair includes a one-way clutch that allows only forward rotation of the sheet in the sheet conveying direction and that conveys the sheet. A cover member having clutch release means for enabling forward / reverse rotation of the roller pair and capable of opening at least a part of the transport path on the upstream side of the transport roller pair in the paper transport direction; And adopts a configuration that operates the above declutching means in association with the opening operation of the cover member.
[0008]
According to a third aspect of the present invention, in the paper conveying apparatus according to the second aspect , the clutch release means is a pivot member that is pivotally supported to hold the clutch pawl of the one-way clutch, and the pivot member. In a state where the operation member is provided integrally, and the cover member is closed, the operation member contacts the cover member, the clutch pawl engages with the clutch gear of the one-way clutch, and the cover member In the opened state, the clutch pawl, the rotating member, and the operation member are rotated by their own weights to remove the clutch pawl from the clutch gear .
[0009]
According to a fourth aspect of the present invention, in the paper conveying apparatus according to the third aspect, the clutch pawl, at least a part of the rotating member, and the operation member are integrally formed by a single leaf spring. Yes.
[0010]
According to a fifth aspect of the present invention, in the image forming apparatus for conveying a sheet to a transfer portion by a sheet conveying device so as to synchronize with an image formed on the image carrier, and transferring the image onto the sheet , the sheet conveying device. Is a paper transport device according to one of claims 1 to 4 .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a printer 2 as an image forming apparatus in this embodiment includes a paper transport device 4, a photoconductor 6 as an image carrier positioned above the paper transport device 4, a transfer belt 8, A fixing unit 10 is provided above the photosensitive member 6 and fixes the transferred image (toner image) on the paper P. The paper discharge roller pair 12 is provided. That is, the printer 2 is configured to convey the paper substantially vertically.
[0013]
The paper transport device 4 includes a paper feed unit 14 , a transport roller pair 16 provided downstream of the paper feed unit 14 in the paper transport direction, and a registration roller pair 18 provided downstream of the transport roller pair 16 in the paper transport direction. Have.
The paper feed means 14 is in contact with the upper surface of the paper feed tray 20 and a plurality of papers P stacked on the paper feed tray 20 and feeds the uppermost paper P to the transport roller pair 16 side which is the paper transport direction. A paper roller 22, a separation pad 24 provided to face the paper supply roller 22, a pressure spring 26 that presses the separation pad 24 against the paper supply roller 22, and the like. The paper P is pressed against the paper feed roller 22 by lifting means (not shown).
[0014]
When the paper feed roller 22 is rotated by a paper feed signal from a control means (not shown), only the uppermost paper P is separated and sent to the transport roller pair 16. The conveying roller pair 16 has a driving roller 16a and a driven roller 16b. The transport roller pair 16 is positioned substantially vertically above the paper feed roller 22, and the paper P is transported along the guide plate 28. A cover member 30 that can open at least a part of the conveyance path on the upstream side in the sheet conveyance direction of the conveyance roller pair 16 is provided below the conveyance roller pair 16.
The registration roller pair 18 includes a driving roller 18a and a driven roller 18b.
[0015]
Although not shown, a charging unit that uniformly charges the surface of the photosensitive member 6 and a developing unit that visualizes an electrostatic latent image formed by exposure light, as is well known, around the photosensitive member 6. In addition, a cleaning unit that cleans residual toner on the photoconductor 6 after transfer, a static elimination unit that removes residual charges on the photoconductor 6, and the like are provided.
The paper P on which the image on the photoconductor 6 is transferred by the transfer belt 8 enters the fixing unit 10. The fixing unit 10 includes a fixing roller 10a having a halogen heater therein and a pressure roller 10b pressed against the fixing roller 10a. The toner is melted and fixed on the paper P by heat and pressure. . The fixed paper P is stacked on a paper discharge tray (not shown) by a paper discharge roller pair 12.
[0016]
As shown in FIGS. 2 and 3, only the forward rotation of the pair of transport rollers 16 to transport the paper P in the paper transport direction is performed in the non-sheet passing region of the drive shaft 16 c of the drive roller 16 a of the transport roller pair 16. A permissible one-way clutch 32 is provided, and a clutch release means 34 that enables forward / reverse rotation of the conveying roller pair 16 is provided.
The one-way clutch 32 has a clutch gear 36 and a substantially V-shaped clutch pawl 38 that engages with a tooth groove 36 a of the clutch gear 36. The clutch release means 34 includes a rotating member 40 that integrally holds the clutch pawl 38 and an operation member 42 that is provided integrally with the rotating member 40. The rotating member 40 has a shape bent in a U-shape, and is rotatably supported by a shaft 44 provided below the drive shaft 16c.
[0017]
The lower end portion of the cover member 30 is supported by a shaft 46 so as to be opened and closed, and magnets 48 for obtaining a catching force when the cover member 30 is closed are provided on both inner sides thereof. Corresponding to the position of the magnet 48, ferromagnetic brackets 50 are provided on both sides of the guide plate 28 (not shown in FIG. 1 and the like).
The clutch pawl 38, the rotation member 40, and the operation member 42 are integrally formed by bending one leaf spring. In addition, these integrated configurations are balanced so that the shaft 44 rotates in the direction of arrow C when no external force is applied.
[0018]
As shown in FIG. 3, when the cover member 30 is closed, the free end of the operation member 42 is pressed against the inner surface of the cover member 30 by the elastic force of the leaf spring, and the clutch pawl 38 is engaged with the tooth groove 36 a of the clutch gear 36. Engage without rattling. In this state, the drive roller 16a of the transport roller pair 16 is allowed to rotate only in the direction of arrow A and only forward rotation to transport the paper P in the paper transport direction. In this forward rotation, the inclined surface of the tooth gap 36a is formed so that there is almost no rotational load due to contact of the clutch pawl 38.
As shown in FIG. 2, the magnet 48, the ferromagnetic bracket 50, the one-way clutch 32, the clutch release means 34, etc. are provided in the non-sheet passing area so as not to hinder the conveyance of the paper P.
[0019]
When it is detected by a paper sensor (not shown) that the leading edge of the paper P sent out by the paper supply means 14 has passed through the transport roller pair 16 and has reached the registration roller pair 18, the transport roller pair 16 is driven for a predetermined time, Overfeed is performed. As a result, a deflection Pa is formed at the leading end of the paper P as shown in FIG. Due to the elastic force of the deflection Pa, the leading edge of the paper P follows the nip line of the nip portion of the registration roller pair 18, so that the posture deviation of the paper P is corrected.
When the registration roller pair 18 is driven at a predetermined timing, that is, at a timing at which a predetermined position of the leading end portion of the paper P is synchronized with an image formed on the photoreceptor 6, the paper P is in a state in which the posture deviation is corrected. And is sent to a transfer nip portion between the photosensitive member 6 and the transfer belt 8. In FIG. 1, an alternate long and two short dashes line Pb indicates a conventional deflection.
[0020]
Although the transport roller pair 16 is stopped when the excessive feeding is finished, the reverse rotation is not allowed by the function of the one-way clutch 32, so that the paper P is prevented from flowing back by the elastic force when the flexure Pa is formed. Is done. Therefore, no sheet deflection is formed between the conveying roller pair 16 and the sheet feeding means 14, and the occurrence of a tensing noise due to this is prevented.
Further, since the magnitude of the deflection Pa does not flow backward and does not become small, there is an advantage that the initial deflection force is maintained and the correction function by the abutment of the registration roller pair 18 against the nip portion is not reduced.
[0021]
When the paper P is jammed in the vicinity of the conveyance roller pair 16, the cover member 30 is opened as shown in FIG. When the cover member 30 is opened, the restraint of the cover member 30 with respect to the operation member 42 is released, so that the integral structure of the rotation member 40 and the like rotates in the direction of the arrow C by its own weight. The clutch pawl 38 is released from 36a. That is, the clutch gear 36 and the clutch pawl 38 in the one-way clutch 32 are disengaged. Accordingly, the driving roller 16a of the conveying roller pair 16 can rotate in the directions of arrows A and B, that is, forward / reverse.
As a result, as shown in FIG. 5, the sheet P can be arbitrarily taken out in the upward (arrow U direction) or downward (arrow D) direction of the conveying roller pair 16 with the cover member 30 opened to a predetermined position. .
[0022]
In the above embodiment, the clutch release means 34 is operated in accordance with the opening operation of the cover member 30, but the operation member 42 is replaced with an actuator such as a solenoid, and the clutch pawl 38 is removed by turning on and off the switch. Also good. In this case, the switch may be turned on / off by opening / closing the cover member 30.
[0023]
In the above embodiment, the paper conveying device 4 in the image forming apparatus has been described. However, the same can be applied to an auto document feeder (ADF).
[0024]
【The invention's effect】
According to claim 1 or 5 invention described, without reducing the sheet jam processing of the conveyance roller pair near, the noise can be reduced by bracing sound.
[0025]
According to the second or fifth aspect of the present invention, an operation for operating the clutch release means becomes unnecessary, and the operability can be improved .
[0026]
According to the invention of claim 3 or 5, wherein the operation for operating the clutches releasing means is not required, it is possible to improve the operability.
[0027]
According to the invention of claim 4 or 5 , the number of parts can be reduced and the manufacture can be facilitated, and the backlash of the one-way clutch can be prevented by the elastic force .
[Brief description of the drawings]
FIG. 1 is a schematic front view of a printer as an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view of a one-way clutch and clutch release means.
FIG. 3 is a view showing a relationship between a one-way clutch and a clutch release means in a state where a cover member is closed.
FIG. 4 is a view showing a relationship between a one-way clutch and a clutch release means in a state where a cover member is opened.
FIG. 5 is a diagram illustrating a state in which a cover member is opened and a sheet is taken out.
[Explanation of symbols]
P paper 14 paper feed means 16 transport roller pair 18 registration roller pair 30 cover member 32 one-way clutch 34 clutch release means 38 clutch pawl 36 clutch gear 40 rotating member 42 operation member

Claims (5)

A sheet feeding means for feeding the stacked paper sheet by sheet, and a pair of conveying rollers provided in the paper conveying direction downstream side of the paper feed unit, the conveying roller pair downstream in the sheet conveying direction in provided we resist rollers The pair of registration rollers forms a bend at the leading edge of the sheet with the leading edge of the sheet abutting against the nip of the registration roller pair, and after the alignment of the sheet is aligned, the registration roller pair performs the following at a predetermined timing. In a paper transport device that transports paper to the section of
A one-way clutch that permits only forward rotation of the pair of transport rollers in the sheet transport direction, and clutch release means that enables forward / reverse rotation of the pair of transport rollers ; A sheet conveying apparatus , wherein the clutch releasing means includes a rotating member that is pivotally supported to hold the clutch pawl of the one-way clutch, and an operation member that rotates the rotating member . A sheet feeding unit that feeds the stacked sheets one by one, a pair of conveyance rollers provided on the downstream side of the sheet conveyance direction of the sheet feeding unit, and a pair of registration rollers provided on the downstream side of the conveyance roller pair in the sheet conveyance direction And forming a deflection at the leading edge of the sheet with the leading edge of the sheet abutting on the nip portion of the registration roller pair, and aligning the positional deviation of the sheet, and then at the predetermined timing by the registration roller pair. In a paper transport device that transports paper to a section ,
A one-way clutch that permits only forward rotation of the pair of transport rollers in the sheet transport direction, and clutch release means that enables forward / reverse rotation of the pair of transport rollers; A sheet conveying apparatus having a cover member capable of opening at least a part of a conveying path on the upstream side in the sheet conveying direction of a pair of conveying rollers, wherein the clutch release means operates in accordance with the opening operation of the cover member. . In the paper conveying apparatus according to claim 2 ,
The clutch release means includes a rotary member that is pivotally supported to hold the clutch pawl of the one-way clutch, and an operation member provided integrally with the rotary member, and the cover member is closed. In the state, the operation member abuts on the cover member and the clutch pawl is engaged with the clutch gear of the one-way clutch. In the state where the cover member is opened, the clutch pawl, the rotation member and the entire operation member are A paper transporting device that rotates by its own weight and removes the clutch pawl from the clutch gear . In the paper conveying apparatus of Claim 3,
The paper conveying apparatus , wherein the clutch pawl, at least a part of the rotating member, and the operation member are integrally formed by one leaf spring . In an image forming apparatus that conveys a sheet to a transfer portion by a sheet conveying device so as to synchronize with an image formed on an image carrier, and transfers the image onto the sheet .
An image forming apparatus , wherein the sheet conveying apparatus is the sheet conveying apparatus according to claim 1 .

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