JP2003192180A - Sheet conveyance device, sheet feeding device, image formation device, and image reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveyance device and a sheet feeding device capable of reducing noise caused by springing up of a rear end and feeding paper sheets including a sheet having weak stiffness and a sheet having strong stiffness and to provide an image formation device and an image reading device provided with the same. <P>SOLUTION: A curved guide 33 is provided with an auxiliary guide 34 which moves to the vicinity of a nip part of a feed roller 31 and a retard roller 32 after a tip part of the sheet conveyed by the feed roller 31 passes to guide the sheet so as to swing freely against the curved guide 33. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus or an image forming apparatus, such as a scanner, a copying machine, a printer, or a facsimile apparatus, for reading an image of an original or forming an image on a sheet. In particular, the present invention relates to a sheet conveying device and a sheet feeding device for conveying a sheet, which are provided in these devices.

[0002]

2. Description of the Related Art A conventional sheet feeding apparatus of this type will be described with reference to FIG.

First, a sheet S is loaded on an intermediate plate 142 which is rotatably fixed in a paper feed cassette 141.

A lifter plate 143, which is rotatably fixed to the lower portion of the middle plate 141, rotates in the direction of the arrow in the figure based on information from a paper surface height detection device (not shown), and the inside of the paper feed cassette 141 Adjust the seat height constantly.

In response to a drive signal from the main body, the pickup roller 130 descends by the action of a solenoid (not shown), and the pickup roller 130 is driven by a drive means (not shown).
Rotates in the direction of the arrow in the figure. Further, the feed roller 131 and the retard roller 132 which are being driven together also rotate in the direction of the arrow in the figure.

However, a torque limiter (not shown) is provided on the axis of the retard roller 132, and a drive reverse to the sheet conveying direction is input.

As a result, even if two or more sheets S are fed, they can be separated and conveyed one by one to the image forming section.

Further, the feed roller 13 is provided on the downstream side.
A curved guide 133 that swings around 133a in accordance with the operations of a guide plate 144 for guiding the sheet S conveyed by 1 to the vertical pass roller 136 and the opening / closing door 140.
Is provided. Further, a guide plate 138 is provided for the opening / closing door 140.

[0009]

However, in the case of the above-mentioned prior art, the following problems have occurred.

Usually, the retard roller 132 and the curved guide 133 which is a guide for the sheet are fixed in order to prevent the leading end of the sheet S from being caught by the curved guide 133 in consideration of curl and the like generated by moisture absorption and drying of the sheet S. The step d is provided, but due to the step d, the rear end of the sheet S bounces on the curved guide 133 due to the elasticity of the sheet S at the moment when the sheet S passes through the retard roller 132 (hereinafter, the rear end It was happening).

The energy generated thereby propagates as sound.

Further, since it occurs at regular intervals during continuous sheet feeding, it is uncomfortable for the user.

Conventionally, the curvature of the sheet passing portion has been made small in order to reduce these trailing edge flickering noises.
This has led to an increase in the size of the device and has been a barrier to downsizing of the device.

To solve these problems, it has been proposed to provide an auxiliary guide that swings as the sheet passes and that holds the rear end of the sheet so as to project from the curved guide.

However, since the auxiliary guide is provided so as to project from the curved guide at the home position, when a weak sheet such as thin paper is conveyed, the auxiliary guide cannot be swung, and the reverse guide is not provided. There is a concern that it may get caught in the auxiliary guide and cause a paper jam.

The present invention has been made in order to solve the above-mentioned problems of the prior art. The object of the present invention is to eliminate the noise caused by the trailing edge and to feed sheets from a weak to a strong sheet. An object of the present invention is to provide a sheet conveying device capable of forming paper, a sheet feeding device, and an image forming apparatus and an image reading apparatus including these.

[0017]

In order to achieve the above object, according to the present invention, a sheet conveying means for conveying a sheet along a sheet conveying path, and a swingable downstream side of the sheet conveying means. A first guide member that is provided and that changes the transport direction of the sheet that is transported by the sheet transport means; and a second guide member that is swingably provided on the first guide member and that is disposed outside the sheet transport path. And a second guide member, the second guide member being moved to the vicinity of the sheet conveying means as the sheet conveyed by the sheet conveying means passes through the sheet conveying device. It is characterized by guiding the rear end side.

When the first guide member swings with respect to the second guide member, the downstream end or the upstream end of the second guide member is positioned in the sheet conveying path. When the sheet is not conveyed, the second guide member presses the first state located outside the sheet conveying path and the leading end portion of the sheet conveyed by the sheet conveying means. A second state in which the removed first guide member swings, the second guide member projects from the first guide member and is located in the sheet conveyance path, and the second state. When the sheet is conveyed, the leading end portion of the sheet presses the downstream end portion protruding from the first guide member, the second guide member swings, and the second guide member swings. The upstream end of the guide member of the sheet Located feed path, it is also suitable to have a third state for guiding the rear end of the sheet.

In the first state, it is also preferable that at least the downstream end portion of the second guide member is held inside the first guide member.

It is also preferable to include holding means for holding the first guide member and the second guide member in the first state.

It is also preferable that the holding means includes a biasing means for biasing the second guide member to a position to be taken in the first state.

It is also preferable that the biasing means is a tension spring or a torsion spring.

When the sheet is detected by the sheet detecting means and the sheet detecting means for detecting the sheet conveyed on the sheet conveying path, at least the second guide member is swung at a predetermined timing to move the sheet. It is also preferable to include a control unit that moves the sheet conveyance unit to the vicinity thereof.

When the sheet is not conveyed, the second guide member is located outside the sheet conveying path, and when the sheet conveyed by the sheet conveying means is detected by the sheet detecting means. In addition, it is preferable to have a state of being swung by the control means and positioned in the sheet conveying path and guiding the rear end side of the sheet.

It is also preferable that the control means includes a solenoid or an actuator, and the solenoid or actuator moves the second guide member.

In the sheet feeding device, the sheet stacking means for stacking the sheets, the sheet separating and feeding means for separating the sheets stacked by the sheet stacking means one by one, and feeding the sheets, the sheet conveying means described above. An apparatus, and the sheet fed by the sheet separating / feeding unit is conveyed by the sheet conveying apparatus along the sheet conveying path.

An image forming apparatus is provided with at least one of the above-described sheet conveying device and the above-mentioned sheet feeding device, and an image forming means for forming an image on a sheet. Characterize.

An image reading apparatus is provided with at least one of the above-described sheet conveying apparatus and the above-mentioned sheet feeding apparatus, and an image reading means for reading image information of a sheet. Characterize.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
The material, the shape, and the relative arrangement of them should be appropriately changed depending on the configuration of the device to which the invention is applied and various conditions, and the scope of the invention is not limited to the following embodiments.

FIG. 1 is a schematic sectional view of an image forming apparatus having a sheet conveying device according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a copying machine main body as an image forming apparatus, and an original table 2 made of a transparent glass plate fixedly provided on the copying machine main body 1.

Reference numeral 3 denotes an original pressing plate which presses and fixes an original O placed at a predetermined position on the original table 2 with the image surface facing downward. A lamp 4 for illuminating the document O is provided below the document table 2.
And an optical system composed of reflecting mirrors 5, 6, 7, 8, 9, 10 for guiding the illuminated optical image of the original O to the photosensitive drum 12 and an image forming lens 11. The lamp 4 and the reflection mirrors 4, 5, 6, 7 move in the direction of arrow a at a predetermined speed to scan the original O.

The image forming unit including the image forming means includes the photosensitive drum 12, the charger 13 for uniformly charging the surface of the photosensitive drum 12, and the surface of the photosensitive drum 12 charged by the charger 13 as described above. The developing device 14 for developing the electrostatic latent image formed by the optical image emitted from the optical system to form the toner image to be transferred to the sheet S, and the toner image developed on the surface of the photosensitive drum 12. A transfer charger 19 for transferring to the sheet S, and a separation charger 20 for separating the sheet S on which the toner image is transferred from the photosensitive drum 12
And a cleaner 26 for removing the toner remaining on the photosensitive drum 12 after the toner image is transferred.

On the downstream side of the image forming section, a conveying section 21 for conveying the sheet S having the toner image transferred thereon, and a conveying section 2
A fixing device 22 for fixing the image on the sheet S conveyed by 1 as a permanent image is provided.

Further, a discharge roller 24 for discharging the sheet S having the image fixed by the fixing device 22 from the copying machine main body 1 is provided. Further, the discharging roller 24 is discharged outside the copying machine main body 1. A discharge tray 25 for receiving the stacked sheets S is provided.

Next, a detailed description will be given with reference to FIG. 2 showing a schematic cross section of the sheet feeding devices 50 and 51 according to the present embodiment shown in FIG.

First, the sheets S are stacked on the intermediate plate 42 which is rotatably fixed in the sheet feeding cassette 41 as the sheet stacking means. Then, the lifter plate 43, which is rotatably fixed to the lower portion of the middle plate 42, rotates in the direction of the arrow in the figure based on the information of the sheet height detection device (not shown), and the paper feed cassette 4
Adjust the paper height in 1 to a constant value.

In response to a drive signal from the main body, the pickup roller 30 is lowered by the action of a solenoid (not shown), and the pickup roller 30 is rotated in the direction of the arrow by a drive means (not shown). Further, the feed roller 31 and the retard roller 32, which are both driven, also rotate in the direction of the arrow in the figure at the same time.

However, a torque limiter (not shown) is provided on the axis of the retard roller 32, and a drive reverse to the sheet conveying direction is input. As a result, even if two or more sheets S are fed, they can be separated and conveyed one by one to the image forming unit. Here, the sheet separating / feeding means includes a pickup roller 30, a feed roller 31, and a retard roller 32. Further, the sheet conveying means is at least the feed roller 31.
It is composed of.

A feed roller 31 is provided on the downstream side.
Of the guide plate 44 and the opening / closing door 40 for guiding the sheet S conveyed by the vertical path roller 36, and a curved guide as a first guide member that swings around the shaft 33a in accordance with the passage of the sheet. 33 are provided. 38 and 39 are also provided as guide plates for the opening / closing door 40.

Further, an auxiliary guide 34 as a second guide member, which operates in response to the passage of the sheet, is swingably supported by the bending guide 33.

Here, in the sheet conveying apparatus according to the present embodiment, at least the feed roller 31 and the bending guide 3 are provided.
The sheet feeding device is constituted by the sheet conveying device, the sheet feeding cassette 41, and the sheet separating and feeding means (pickup roller 30, feed roller 31, retard roller 32). .

Next, the structure of the bending guide 33 and the auxiliary guide 34 will be described with reference to FIGS.

FIG. 3 shows a perspective view in which the auxiliary guide 34 is attached to the bending guide 33, FIG. 4 shows each function of the auxiliary guide 34, and FIG. 5A shows details of the attaching portion of the auxiliary guide 34 in the bending guide 33. FIG. 3B is a sectional view taken along the line AA of FIG.

The auxiliary guide 34 includes a sheet detecting portion 34a as a downstream end portion for detecting the passage of the sheet S, and a sheet guide portion 34 as an upstream end portion for guiding the sheet rear end side.
b, a snap-fit portion 34c which is coupled to the bending guide 33 and serves as a rotation center of the auxiliary guide 34, and a groove 34d in which the return spring 35 is attached.

In this auxiliary guide 34, a snap-fit portion 34c is so-called patching-fixed by a snap action on a shaft portion 33b formed on the curved guide 33, and is swingably supported with respect to the curved guide 33. The return spring 35 can be hooked on a spring chip portion (not shown) formed on the unit.

Here, the bending guide 33 and the auxiliary guide 3
4, the return spring 35 (biasing means, holding means) biases the auxiliary guide 34, thereby providing a step to the nip portion between the feed roller 31 and the retard roller 32 as described in the related art. Position (first described later)
State).

The return spring 35 is preferably a tension spring or a torsion spring, and may be held at this position (first state) by providing, for example, a restricting portion as a holding means.

Such an auxiliary guide 34 is used as the bending guide 3.
A plurality of them are attached on top of 3.

Next, the auxiliary guide 3 accompanying the passage of the sheet S
The operation of No. 4 will be described with reference to FIG.

FIG. 6 shows the auxiliary guide 34 on standby. At this point, the auxiliary guide 34 has the curved guide 33.
However, the auxiliary guide 34 is not exposed on the sheet conveying path formed by the curved guide 33 (first state).

That is, the bending guide 33 and the auxiliary guide 34 are held at the position where a step is provided with respect to the nip portion between the feed roller 31 and the retard roller 32, and the conveyed sheet is prevented from being caught by the guide. It is preventing.

When the sheet S is sent out by the feed roller 31, the bending of the sheet causes the bending guide 33 to swing in the direction A in the figure as shown in FIG. By this action, the sheet detecting portion 34a of the auxiliary guide 34
Protrudes with respect to the curved guide 33, and the auxiliary guide 34 is exposed on the sheet conveying path (second state).

Next, as shown in FIG. 8, the auxiliary guide 34
Swings due to the stiffness of the seat and snap-fit part 3
The sheet guide portion 3 rotates around the portion 4c in the direction A in the drawing.
4b approaches the vicinity of the retard roller 32 (third state).

The third state shown in FIG. 8 is maintained until the sheet S passes through the auxiliary guide 34, and the auxiliary guide 34 guides the area on the rear end side of the front end of the sheet S.

As a result, the step between the nip portion between the feed roller 31 and the retard roller 32 and the curved guide 33 can be eliminated, so that the sheet is generated when the sheet passes through the pair of the feed roller 31 and the retard roller 32. The trailing edge of the sheet S can be prevented.
In addition, the auxiliary guide 34 that swings with respect to the bending guide 33
Since the area on the rear end side of the sheet S is guided by the sheet, the amount of swing of the bending guide 33 can be reduced, and the apparatus can be downsized.

When the sheet S passes through the auxiliary guide 34, the bending spring 33 and the auxiliary guide 34 return to the home position (first state) shown in FIG. 6 by the action of the return spring 35.

When the sheet S sent out by the feed roller 31 is a weak sheet, the curved guide 33 does not swing on the weak sheet, and the auxiliary guide 34 is exposed on the sheet conveying path. There is no.
That is, since the auxiliary guide 34 maintains the state (first state) held inside the bending guide 33, the sheet having a weak stiffness is guided by the bending guide 33 and conveyed to the downstream side. When the sheet having a weak stiffness passes through the roller pair of the feed roller 31 and the retard roller 32, the trailing edge fuzz which causes unpleasant noise does not occur.

As described above, by providing the curved guide 33 and the auxiliary guide 34, the nip portion between the feed roller 31 and the retard roller 32 and the curved guide 33.
It is possible to eliminate the step between the sheet and the sheet, and it is possible to prevent the trailing edge of the sheet S that occurs when the sheet passes through the roller pair of the feed roller 31 and the retard roller 32, and it is possible to prevent unpleasantness during sheet feeding. The noise can be reduced or eliminated.

Therefore, the silencing effect can be brought about without increasing the curvature of the bending guide portion 33, and the miniaturization of the device can be realized.

Further, the auxiliary guide 34 is the bending guide 3
3, the auxiliary guide 34 is operated according to the response of the bending guide 33, so that the weak guide sheet such as thin paper is guided by the bending guide 33, and there is the stiffness of thick paper. For the sheet, since the auxiliary guide 34 can be operated to guide the rear end of the sheet, a sheet with a weak stiffness does not get caught in the auxiliary guide 34, and a wide range of sheets from thin paper to thick paper can be supported. Is possible. In addition, since the auxiliary guide 34 that swings with respect to the bending guide 33 guides the region on the rear end side of the sheet S, the amount of swinging of the bending guide 33 can be reduced, and the device can be downsized. Becomes

Further, since the trailing edge can be suppressed, the trailing edge prevents the sheet from colliding with the guide plate, the edge of the sheet can be prevented, and a high quality image can be formed. .

In the present embodiment, the return spring 35 causes the auxiliary guide 34 to move to the home position (first state).
I was returning to, but changed the shape of the auxiliary guide 34,
By setting the center of gravity of the auxiliary guide 34 below the snap fit portion 34c and the center of gravity of the bending guide 33 below the shaft 33a of the bending guide 33, the home position (first state) is returned by its own weight. Since the return spring can be omitted, the cost can be reduced.

Further, in the present embodiment, the auxiliary guide 34 is operated by the stiffness of the sheet. However, the solenoid or the clutch and the cam are used by using the sensor signal of the sheet detecting means for detecting the sheet conveyed on the sheet conveying path. A control means 40 for controlling at least the operation of the auxiliary guide 34 in accordance with the sensor signal by using an actuator such as
By providing, it becomes possible to perform more precise control. In this case, the auxiliary guide 34 only needs to have the sheet guide portion 34b that is provided so as to be swingable with respect to the bending guide 33, and is controlled by the control means in the first state or the third state described above at a predetermined timing. The effect described above is obtained by controlling to the state of.

In the present embodiment, the paper feeding unit of the image forming apparatus has been described, but the present invention is not limited to this, and the present invention is also applicable to a conveyance guide unit (sheet conveying device) having a small curvature or an image reading apparatus. It is possible.

[0066]

As described above, according to the present invention,
By providing the first guide member and the second guide member, it is possible to prevent the trailing edge flapping of the sheet that occurs when the sheet passes through the sheet conveying unit, and thus unpleasant noise that occurs during sheet feeding. It is possible to provide a muffling effect that reduces or eliminates. Therefore, it is possible to reduce the size of the device without increasing the curvature of the bending guide as in the conventional case.

Further, by moving the second guide member disposed outside the sheet conveying path to the vicinity of the sheet conveying means as the sheet passes, the sheet with weak stiffness becomes the second guide member. Since it is guided by the first guide member without being caught, it is possible to handle a wide range of sheets from thin paper to thick paper.

[Brief description of drawings]

FIG. 1 is a main cross-sectional view of an image forming apparatus according to this embodiment.

FIG. 2 is a main cross-sectional view of the sheet feeding device according to the present embodiment.

FIG. 3 is a schematic perspective view of a bending guide 33 according to the present embodiment.

FIG. 4 is a schematic perspective view of an auxiliary guide 34 according to the present embodiment.

FIG. 5 shows a bending guide 33 according to the present embodiment,
(A) is a detailed view of an attachment portion of the auxiliary guide 34, and (b) is a sectional view taken along line AA of (a).

FIG. 6 is an operation diagram of the auxiliary guide 34 according to the present embodiment.

FIG. 7 is an operation diagram of the auxiliary guide 34 according to the present embodiment.

FIG. 8 is an operation diagram of the auxiliary guide 34 according to the present embodiment.

FIG. 9 is a schematic cross-sectional view of a sheet feeding unit showing a conventional technique.

[Explanation of symbols]

30 pickup roller 31 Feed roller 32 retard roller 33 Curved guide 33a axis 33b Shaft 34 Auxiliary guide 34a Sheet detection unit 34b Guide part 34c Snap fit part 34d groove 35 Return spring 36 Vertical path roller 41 paper feed cassette 42 Middle plate 43 Lifter plate 44 Guide plate

Claims (12)

[Claims] 1. A sheet transporting means for transporting a sheet along a sheet transporting path, and a swingable downstream side of the sheet transporting means for changing the transporting direction of the sheet transported by the sheet transporting means. A sheet conveying device comprising: a first guide member; and a second guide member swingably provided on the first guide member and arranged outside the sheet conveying path, the second guide member comprising: The sheet guide device according to claim 1, wherein the guide member moves to the vicinity of the sheet conveyer as the sheet conveyed by the sheet conveyer passes and guides the rear end side of the sheet. 2. When the first guide member swings with respect to the second guide member, the downstream end portion or the upstream end portion of the second guide member is in the sheet conveying path. The second guide member has a first state in which the second guide member is located outside the sheet conveying path when the sheet is not conveyed, and a leading end portion of the sheet conveyed by the sheet conveying unit. The first guide member, which is pressed by
A second state in which the guide member of is protruded from the first guide member and is positioned in the sheet conveying path; and when the sheet is conveyed more than in the second state,
The leading end of the sheet presses the downstream end protruding from the first guide member, the second guide member swings, and the upstream end of the second guide member moves. The sheet conveying apparatus according to claim 1, further comprising: a third state which is located in the sheet conveying path and guides a rear end side of the sheet. 3. In the first state, at least the downstream end of the second guide member is held inside the first guide member. The sheet conveying device described. 4. The sheet conveying apparatus according to claim 1, further comprising holding means for holding the first guide member and the second guide member in the first state. 5. The sheet conveying apparatus according to claim 4, wherein the holding unit includes a biasing unit that biases the second guide member at a position to be set in the first state. 6. The sheet conveying apparatus according to claim 5, wherein the urging means is a tension spring or a torsion spring. 7. A sheet detecting means for detecting a sheet conveyed on the sheet conveying path, and a case where the sheet is detected by the sheet detecting means,
The sheet conveying apparatus according to claim 1, further comprising: a control unit that swings at least the second guide member at a predetermined timing to move the second guide member to a position near the sheet conveying unit. 8. A state in which the second guide member is positioned outside the sheet transport path when the sheet is not transported, and a sheet transported by the sheet transport means is detected by the sheet detection means. The sheet conveying apparatus according to claim 7, further comprising: a state in which the sheet is swung by the control unit to be positioned in the sheet conveying path and guides a rear end side of the sheet. 9. The sheet conveying apparatus according to claim 8, wherein the control means includes a solenoid or an actuator, and the solenoid or the actuator moves the second guide member. 10. The sheet stacking means for stacking sheets, and the sheet separating / feeding means for separating and stacking the sheets stacked by the sheet stacking means one by one, according to any one of claims 1 to 9. The sheet feeding apparatus according to claim 1, wherein the sheet fed by the sheet separating / feeding unit is fed along the sheet feeding path by the sheet feeding apparatus. 11. An image forming apparatus for forming an image on a sheet, and at least one of the sheet conveying apparatus according to claim 1 and the sheet feeding apparatus according to claim 10. An image forming apparatus comprising: 12. An image reading device for reading image information of a sheet, and at least one of the sheet conveying device according to any one of claims 1 to 9 and the sheet feeding device according to claim 10. An image reading apparatus comprising: