JP2001158549A - Paper sheet conveying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper sheet conveying device capable of preventing folding of a paper sheet at an edge and failure in conveying the paper sheet caused by abutting on a jaw part of a ratchet wheel at an end part of the paper sheet and being caught, especially failure in conveying the paper sheet caused by drift of the end part of the paper sheet followed by abutting on the jaw part of the ratchet wheel when the paper sheet is vertically upward conveyed in a paper sheet conveying passage. SOLUTION: In this paper sheet conveying device for guiding and conveying the paper sheet S by a paper sheet conveying guide plate 31 and the ratchet wheel 33 rotatably supported thereon, a projecting part 31C comprising an inclined plain from an upstream side of a paper sheet conveying direction to near an outer diameter part of the ratchet wheel 33 is provided on a paper sheet guide plain of the paper sheet guide plate 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper conveying apparatus, and more particularly to an electrophotographic copying machine, a printer, a facsimile,
The present invention relates to a sheet transport device provided in an image forming apparatus such as a multifunction peripheral or a printing machine having a plurality of functions.

[0002]

2. Description of the Related Art Generally, in order to convey a sheet in a predetermined direction by a sheet conveying device, a sheet conveying guide plate and a flexible thin plate which is supported by a part of the sheet conveying guide plate and which can be elastically deformed are used. ing.

[0003] Further, in a paper transporting device that transports and transports powder such as unfixed toner on the paper surface, a sliding contact between the paper guide surface of the paper transport guide plate and the paper surface is minimized. A ratchet wheel rotatably supported is used.

However, due to paper deformation such as curling of the leading end of the paper, the leading end of the paper hits the pawl of the ratchet wheel,
Paper conveyance failure may occur.

[0005] In particular, in a sheet conveying device that forms a vertical conveying path that conveys a sheet substantially vertically upward, the position of the leading end of the sheet passing between a pair of sheet conveying guide plates that form the vertical conveying path is determined. The sheet is unstable and hits the claw portion of the ratchet wheel, so that a sheet conveyance failure is likely to occur.

FIG. 7 is a cross-sectional view of a conventional sheet conveying device in an image forming apparatus. The image forming apparatus includes an image carrier 1
The toner image formed on the sheet 0 is transferred to a sheet S by a transfer unit (not shown), the sheet S is separated from the image carrier 10 by a separation claw 18, and the sheet S is conveyed to a fixing unit by a sheet conveying device.

[0007] The paper transport device includes paper transport guide plates 41 and 4.
2 and ratchet wheels 43 and 44 rotatably supported by the sheet transport guide plate 41. The leading end of the sheet S separated from the image carrier 10 by the separation claw 18 is connected to the sheet transport guide plate 41,
42, and further comes into contact with the claw portion of the first ratchet wheel 43, enters the gap a between the outer peripheral portion of the first ratchet wheel 43 and the paper transport guide plate 41, and Paper conveyance failure may occur.

Similarly, the leading end of the sheet S having passed through the first ratchet wheel 43 passes through the paper transport path between the paper transport guide plates 41 and 42 and hits the pawl portion of the second ratchet wheel 44. Contact, second
Gap b between the outer peripheral portion of the ratchet wheel 44 and the paper transport guide plate 41
And paper feeding failure may occur.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the paper transport apparatus and the image forming apparatus, and achieves a stable paper transport, and in particular, moves the paper upward in a substantially vertical direction. It is an object of the present invention to provide a paper transport device that achieves stable paper transport in a vertical transport path for transport, and a highly reliable image forming apparatus.

[0010]

According to a first aspect of the present invention, there is provided a sheet transport apparatus for guiding a sheet by a sheet transport guide plate and a ratchet wheel rotatably supported by the sheet transport guide plate. A sheet conveying device that conveys a sheet with a sloping surface provided on a sheet guide surface of the sheet conveying guide plate from an upstream side in a sheet conveying direction to an outer diameter portion of the ratchet wheel. (Claim 1).

In the image forming apparatus of the present invention, the toner image formed on the image carrier is transferred to a sheet by a transfer unit, and the sheet is separated from the image carrier by a separation unit. In the image forming apparatus that transports the paper to the fixing unit, the paper transport device has a paper transport guide plate, and a ratchet rotatably supported by the paper transport guide plate, and the paper transport guide plate The paper guide surface is provided with a projection having an inclined surface approaching the outer diameter portion of the ratchet from the upstream side in the paper transport direction (claim 2).

[0012]

Next, an embodiment of the image forming apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram of an image forming apparatus equipped with an automatic document feeder DF and an image reading device (scanner) SC.

The illustrated image forming apparatus main body A includes an image forming section 1, an image processing section 2, an image writing section 3, a high voltage power supply section 4,
The printer 1 includes a paper feeder 5, a fixing device 6, a paper discharger 7, and an ADU 8 for automatic double-sided copying.

An image reading device SC and an automatic document feeder DF are mounted on the upper part of the image forming apparatus main body A. A paper discharge tray 9 or a paper post-processing device (not shown) can be connected to the paper discharge unit 7 on the upper left side of the image forming apparatus main body A in the figure.

The original d placed on the original table of the automatic document feeder DF with the first side facing upward is conveyed in the direction of the arrow and the image of one or both sides of the original is read by the optical system of the image reading device SC. And read into the CCD image sensor.

The analog signal photoelectrically converted by the CCD image sensor is subjected to analog processing, A / D conversion, shading correction, image compression processing and the like in the image processing section 2 and then sent to the image writing section 3.

In the image writing section 3, the output light from the semiconductor laser is applied to the image carrier 10 of the image forming section 1 to form a latent image. In the image forming section 1, charging,
Processes such as exposure, development, transfer, separation, and cleaning are performed, and an image is transferred to the sheet S transported from the paper transport unit 5. The paper S carrying the image is fixed by the fixing device 6 and discharged from the paper discharge unit 7 to the paper discharge tray 9. Alternatively, the single-sided image-processed sheet S sent to the re-conveying means 8 by the sheet discharge path switching plate 7A is subjected to double-sided image processing again in the image forming section 1 and then to the sheet discharge rollers 7B of the sheet discharge section 7
Is discharged to the discharge tray 9.

In FIG. 1, on the right side of the image forming apparatus main body A, a sheet feeding cassette 5 of a sheet feeding / transporting section 5 is provided below the image forming apparatus main body A in the height direction around the image forming section 1.
A has a fixing device 6 and a paper discharge unit 7 provided above.
With this vertical arrangement, a paper transport path in a substantially vertical direction is formed. The sheet S sent out from the sheet feeding cassette 5A is conveyed along the vertically upper sheet conveying path and discharged out of the image forming apparatus main body A.

A paper transport path by the re-transporting means 8 is formed substantially parallel to the vertical paper transport path. By forming the above-described paper transport path in the vertical direction, a paper transport path of the shortest distance from the paper feed cassette 5A to the paper discharge unit 7 is configured.

FIG. 2 is a sectional view of a main part of an image forming apparatus main body A to which the embodiment of the present invention is applied.

In FIG. 1, reference numeral 10 denotes an image carrier,
This is a photosensitive drum having a photoconductive layer such as Se. The image carrier 10 is driven and rotated in the direction of the arrow. Numeral 11 denotes a pre-charging charge removing means for removing charges remaining on the image carrier 10 before the charging process. A corona charger 12 charges the surface of the image carrier 10 uniformly. Reference numeral 13 denotes an image exposure unit that irradiates a light image onto the image carrier 10 to form an electrostatic latent image. A developing unit 14 develops the electrostatic latent image formed on the image carrier 10 to form a toner image.

Reference numeral 5B denotes a registration roller.
The sheet S fed from A is sent to the transfer position in synchronization with the formation of the electrostatic latent image on the image carrier 10. Reference numeral 15 denotes a transfer unit including a corona discharger for transfer, and transfers the toner image on the image carrier 10 to the sheet S. Reference numeral 16 denotes a simultaneous transfer exposure unit.

Reference numeral 17 denotes a separating means comprising a separating corona discharger, which peels the transferred paper S from the surface of the image carrier 10. Reference numeral 18 denotes a separation claw that is in pressure contact with the surface of the image carrier 10 and peels off the sheet S attached to the image carrier 10. Reference numeral 20 denotes a cleaning device including a cleaning blade 21, a rotary blade member 22, a toner conveying screw 23, and the like.

The sheet S peeled off from the outer peripheral surface of the image carrier 10 by the separating means 17 passes through the sheet conveying device 30 and is conveyed to the fixing device 6.

FIG. 3 is a side view showing the image carrier 10 and the sheet conveying device 30. The paper transport device 30 includes paper transport guide plates 31 and 32 that are opposed to each other, and a plurality of ratchet wheels 43 and 44 rotatably supported by the paper transport guide plate 31. A plurality (2 in FIG.
), And a plurality of (five in the drawing) second ratchets 34 are arranged on the downstream side in the sheet transport direction.

FIG. 4A is a cross-sectional view taken along the line AA of the sheet conveying device 30, and FIG. 4B is a perspective view of the first ratchet wheel 33 and the projection. FIG. 5 is a cross-sectional view taken along the line BB of the sheet transport device 30.

A first ratchet wheel 33 on the upstream side in the sheet transport direction;
Each of the second ratchet wheels 34 on the downstream side in the sheet conveyance direction has a spur shape including a plurality of (twelve illustrated) pawl portions having acute angles. The rotation shaft portion 33A of the first ratchet wheel 33 is rotatably loosely fitted to a bearing portion 31A of the sheet conveyance guide plate 31 on the upstream side in the sheet conveyance direction. The rotation shaft portion 34A of the second ratchet wheel 34 is rotatably fitted to the bearing portion 31B of the sheet transport guide plate 31 so as to be able to roll (see FIG. 5).

On the paper guide surface of the paper transport guide plate 31, a projection 31C having an inclined surface close to the outer diameter portion of the first ratchet wheel 33 is formed from the upstream side in the paper transport direction. The cross section of the top of the projection 31C has an arc shape, and the first ratchet wheel 3
The height h1 from the center of the rotation shaft portion to the top portion is the first height.
Is set smaller than the radius R1 of the outer diameter portion of the ratchet wheel 33 and larger than the radius r1 of the valley portion (R1>h1> r1).

Similarly, a projection 31D having an inclined surface close to the outer diameter of the second ratchet wheel 34 is formed.
The cross section of the top of the projection 31D has an arc shape, and the height h2 from the center of the rotation shaft of the second ratchet wheel 34 to the top is:
The radius R2 of the outer diameter portion of the first ratchet wheel 33 is set to be larger than the radius r2 of the valley portion (R2>h2> r).
2).

The bearings 31A, 31B, the projections 31C,
31D is formed integrally with the sheet transport guide plate 31.

The sheet S separated from the outer peripheral surface of the image carrier 10 by the separating means 17 is sent to a substantially vertical sheet conveying path between the sheet conveying guide plates 31 and 32 of the sheet conveying device 30. When the leading end of the paper S passes through the paper transport path and is in the traveling direction approaching the outer diameter portion of the first ratchet wheel 33, the leading end of the paper S is a protrusion having an inclined surface. 31C
, And is deflected by sliding contact with the claw portion of the first ratchet wheel 33. Since the distance Δ1 between the outer diameter of the claw portion of the first ratchet wheel 33 and the top of the projection 31C is set smaller than the height of the claw portion of the first ratchet wheel 33, the leading end of the sheet is the first After abutting on the claw portion of the ratchet wheel 33, the first ratchet wheel 33 is lightly brought into contact with the outer periphery of the first ratchet wheel 33 to be driven to rotate, and is smoothly transported to the downstream side.

When the leading end of the paper S further advances and comes in the advancing direction approaching the outer diameter of the second ratchet wheel 34,
The leading end of the sheet S is deflected by sliding contact with the projection 31D having an inclined surface, and comes into contact with the claw portion of the second ratchet wheel 34. Second
The distance Δ2 between the outer diameter of the claw portion of the ratchet wheel 34 and the top of the projection 31D is set to be smaller than the height of the claw portion of the second ratchet wheel 34. After the contact with the claw portion 34, the second claw wheel 34 is slightly contacted on the outer periphery thereof, is driven to rotate, and is smoothly transported to the downstream side.

It should be noted that the upstream projection 31C shown in FIG.
Are disposed on both side surfaces of the first ratchet wheel 33, but the present invention is not limited to this, and may be disposed only on any one side surface of the first ratchet wheel 33. Further, the protrusion 31D may be disposed on any one side surface of the second second ratchet wheel 34 on the downstream side.

FIG. 6 is a cross-sectional view of a sheet conveying device provided with a ratchet of another embodiment. In addition, about the code | symbol used for drawing, the part which has the same function as FIG. 4, FIG. 5 is attached | subjected. Further, points different from the above embodiment will be described.

The claw mountain shape of the first ratchet wheel 33 is a trapezoidal triangular shape, and the inclination angle θ1 on the upstream side in the sheet conveying direction is set to a gentle slope larger than the inclination angle θ2 on the downstream side (θ1>).
θ2).

By setting the claw ridge shape of the first ratchet wheel 33 in this manner, the leading end of the conveyed sheet S abuts the gentle slope forming the inclination angle θ1 of the first ratchet wheel 33. Because of the contact, it is possible to prevent the occurrence of paper conveyance failure that is caught by the claw portion of the first ratchet wheel 33. The claw mountain shape of the second ratchet wheel 34 also
A shape similar to that of the first ratchet wheel 33 is set.

In the image forming apparatus of the present invention, the sheet feeding / conveying section 5, image carrier 10, transfer means 15, separating means 17, and sheet conveying apparatus 30 as shown in FIGS. The present invention is not limited to the arranged vertical transport system, but can be applied to an image forming apparatus of a horizontal transport system or the like.

[0039]

According to the paper transport apparatus of the present invention, it is possible to prevent a paper sheet having a large curl at the leading end portion from hitting and catching on the claw portion of a ratchet wheel and to prevent the paper from being bent or a paper transport failure. In particular, when a sheet is conveyed vertically upward in the sheet conveyance path, it is effective to prevent a sheet conveyance failure which occurs when the sheet tip sways and hits the claw portion of the ratchet wheel.

In the image forming apparatus of the present invention, the toner image formed on the image carrier is transferred to the paper by the transfer means, the paper is separated from the image carrier by the separation means, and the paper is fixed by the paper transport device. When the sheet is conveyed to the means, a pawl wheel rotatably supported by a sheet conveying guide plate of the sheet conveying apparatus and a projection having an inclined surface are provided, so that the paper slightly wrapped around the surface of the image carrier can be separated by a separating claw. Light contact with the protruding portion having the inclined surface disposed in the vicinity and the rotatably supported ratchet wheel passes through the paper transport path and is transported to the fixing device. Is reliably prevented,
Stable image formation is achieved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus.

FIG. 2 is a sectional view of a main part of an image forming apparatus main body to which the embodiment of the present invention is applied;

FIG. 3 is a side view illustrating an image carrier and a sheet conveying device.

FIG. 4 is a cross-sectional view taken along line AA of the paper transport device, and a perspective view of a ratchet and a protrusion.

FIG. 5 is a sectional view taken along line BB of the sheet conveying device.

FIG. 6 is a cross-sectional view of a sheet conveying device provided with a ratchet according to another embodiment.

FIG. 7 is a cross-sectional view of a conventional sheet conveying device in the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming part 10 Image carrier 15 Transfer means 16 Simultaneous transfer exposure means 17 Separation means 18 Separation claw 20 Cleaning device 30 Paper transport device 31, 32 Paper transport guide plate 31A, 31B Bearings 31C, 31D Projection 33, 35 No. 1 ratchet wheel 33A, 34A Rotating shaft portion 34, 36 Second ratchet wheel 41, 42 Paper transport guide plate 43, 44 Ratchet wheel A Image forming apparatus main body R1, R2, r1, r2 Radius S Paper a, b Gap h1 , H2 height θ1, θ2 inclination angle Δ1, Δ2 interval

Continuation of the front page (72) Inventor Atsushi Ogane 2970, Ishikawacho, Hachioji-shi, Tokyo Konica Corporation F term in the company (reference) 2H032 AA02 BA19 BA21 DA03 DA12 DA14 3F101 FA01 FB05 FC05 LA02 LA05 LA06 LA07 LB03

Claims (4)

[Claims] 1. A sheet conveying device which guides and conveys a sheet by means of a sheet conveying guide plate and a ratchet wheel rotatably supported by the sheet conveying guide plate. And a protrusion having an inclined surface approaching the outer diameter portion of the ratchet from the upstream side in the paper transport direction. 2. The method according to claim 1, wherein the toner image formed on the image carrier is transferred to a sheet by a transfer unit, the sheet is separated from the image carrier by a separation unit, and the sheet is conveyed to a fixing unit by a sheet conveying device. In the image forming apparatus, the paper transport device includes a paper transport guide plate, and a ratchet rotatably supported by the paper transport guide plate, and a paper guide surface of the paper transport guide plate has a paper transport direction. An image forming apparatus comprising: a projection having an inclined surface approaching an outer diameter portion of the ratchet from an upstream side. 3. A sheet conveying guide plate, wherein a bearing for rotatably supporting a rotating shaft of the ratchet wheel and a projection having the inclined surface are formed integrally with the sheet transport guide plate. Item 3. The image forming apparatus according to Item 2. 4. The apparatus according to claim 2, wherein the paper transporting device forms a vertical transport path for transporting the paper separated from the image carrier by the separating means substantially vertically upward. Image forming device.