JP2000095383A - Sheet feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of an abnormal noise caused by the vibration of a sheet due to the slip phenomenon in continuing the drive of a feed roller in a condition where the sheet is stopped. SOLUTION: This sheet feeder exclusive for manual feed is provided with a paper feed base 32 to guide a sheet to be inserted from a paper feed port 30 to a feed roller 31, and the guide sheet P is fed to a resist roller 20 to stop and arrange a tip of the sheet by the paper feed roller 31. The sheet P is fed by the feed roller 31, and guided along a guide 34 to guide the sheet to the resist roller 20. A second guide 35 is provided along the guide surface of the guide 34 in order to bridge a sheet carrying path between the guide and the feed roller 31. When the feed roller 31 is continuously operated in a condition where the sheet P is stopped by the resist roller 20, the sheet P is vibrated through the slip phenomenon with the sheet P, but the vibration is suppressed by increasing the contact area with the second guide, and thus, the vibration noise is reduced to prevent generation of an abnormal noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus used in an image forming apparatus and the like, and more particularly to a method for stably feeding and guiding fed sheets and simultaneously reducing noise caused by the fed sheets. The present invention relates to a sheet feeding apparatus which prevents the sheet feeding.

[0002]

2. Description of the Related Art In an image forming apparatus, for example, an image forming apparatus using an electrophotographic system, a toner image is formed on a photosensitive member as a recording medium, and the toner image is transferred onto a sheet such as plain paper. In order to hold the upper toner image on the sheet as a permanent image, the toner is fixed by, for example, passing through a heat fixing device, and then discharged outside the apparatus main body.

According to such an image forming apparatus, it is necessary to convey a sheet to an image forming position in order to form a desired image on the sheet. For example, a large number of sheets are stored in a sheet feeding cassette or a tray or the like, and the sheets are sent out one by one from the cassette or the tray to a transport path leading to an image forming unit, particularly, a transfer position where a toner image formed on a photoconductor is transferred. The sheet feeding device configured as described above is provided.

FIG. 8 shows an example of the configuration of the sheet feeding apparatus. Such a sheet feeding device includes a manual sheet feeding port 50.
One more sheet P is inserted, and the sheet P is guided along a sheet feeding table 51 provided so as to be fed from a sheet feeding port 50 to a transfer position of the image forming apparatus. A feed roller 52 for feeding a sheet to a registration roller 56 disposed in front of a transfer position of the image forming apparatus is provided at a leading end of the paper feed table 51. The feeding roller 52 is configured such that, for example, an upper portion is a driving roller 52a, and a lower pressing roller 52b is pressed against the driving roller. The shaft portion of the lower pressure roller 52b is urged by a spring 53 or the like, and is pressed against the drive roller 52a side with an appropriate pressure.

For this reason, the sheet P is inserted along the sheet feeding table 51 through the sheet feeding port 50, and
Is detected by detecting means (not shown). In response to this detection, the feed roller 52 is driven to rotate. The sheet P inserted along the sheet feeding table 51 by this rotation is gripped at the leading end between the feeding rollers 52, and guided and guided toward the registration rollers 55 by the guide 54.

The registration roller 55 starts conveying the sheet P to the transfer position in synchronization with the image forming operation. Therefore, the sheet P is temporarily stopped at the leading end of the sheet P fed through the feed roller 52 and is in a non-driving state. Therefore, the leading edge of the fed sheet P abuts on the nip portion of the registration roller 55 and is aligned.

After that, the sheet P fed through the feed roller 52 is guided along a guide 54, and is fed into a registration roller 55.
Is conveyed to the transfer position by the start of the conveyance. Then, when the conveyance is performed, the rear end of the sheet P is
Pass through. At this time, since the sheet P is guided by the guide 54 so as to change its direction toward the registration roller 55, the sheet rear end collides against the guide 54 with a considerable force due to the return force due to the strength of the sheet's waist. This is usually referred to as sheet jumping or bouncing, and a considerable loud noise is generated when the rear end of the sheet collides with the guide 54 due to the action.

[0008] This collision noise is caused by the sheet P
Each time the vehicle passes through, the noise is very harsh. In order to eliminate this noise, for example, the feeding roller 52
A flexible film-like elastic sheet 56 is provided on the outlet side of the, that is, on the downstream side.
The rebound of the rear end of the seat is absorbed to prevent collision noise. The elastic sheet 56 has a guide 54 at one end.
And the free end side is positioned so as to correspond to the sheet feeding direction by the feeding roller 52.

Therefore, when the sheet P is fed, the sheet P
Deflected in contact with a part of. Then, the rebound at the time of passing the rear end of the sheet can be absorbed by bending as shown by the broken line. Therefore, noise when the rear end of the sheet collides with the guide 54 can be effectively prevented. A technique for preventing such noise is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-150981, and prevents noise due to the rebound of the rear end of the sheet.

[0010]

As described above, according to the sheet feeding apparatus having the structure shown in FIG. 8 provided in the conventional image forming apparatus, the noise caused by the rebound of the sheet is reduced or prevented. It has a great effect.

However, there is a space 56 surrounded by a guide 54 provided between the feeding roller 52 and the registration roller 55 and other guides. The space 56 is formed by a space surrounded by the back surface of the sheet P, the guide 54, and the feeding roller 52. Therefore, space 5
In the air layer of No. 6, the contact sound of the vibration by the feed roller 52 is generated as an abnormal sound.

That is, the feeding roller 52 feeds the sheet P to the registration roller 55, and continues to feed the sheet P even if the leading end of the sheet P is stopped by the registration roller 55. This is because the leading edge of the sheet P is aligned at the nip portion of the registration roller 55, and at the same time, the leading edge of the sheet is securely pinched by the nip portion of the registration roller 55 in a curved state. This is to ensure that P is transported. for that reason,
Since the sheet P continues to rotate even after the sheet P is stopped by the registration roller 55, the feeding roller 52 continues to rotate with the sheet P slipping.

As a result, the sheet P vibrates due to the slip phenomenon of the feed roller 52. The sheet P is a guide 5
Since the sheet P is in contact with the front end area of the sheet 4, the sheet P comes into contact with the vibrating sheet P, and a sound is generated. This sound resonates with the above-described guide 54, the feeding roller 52, and the air layer in the space 56 surrounded by the back surface of the sheet P, and an abnormal sound is generated.
At this point, although the sheet P vibrates on the sheet feeding port 50 side of the feeding roller 52, the sheet feeding port 50 is open, so that even if the sheet P touches the sheet feeding table 51 due to the vibration, a loud noise is generated. Does not occur.

Therefore, by providing the elastic sheet 56,
Although the collision sound caused by the rebound of the trailing edge caused by the passage of the sheet P can be effectively eliminated, the sheet P stopped by the registration roller 55 in the state before the collision is caused by the continuation of the feeding operation of the feeding roller 52. Vibrates due to slip phenomenon. Then, the vibration of the sheet P generates a vibration sound at the fixed guide 54 that comes into contact with the sheet P,
The generation of abnormal noise that resonates with the air layer cannot be eliminated.

Therefore, the rotation of the feed roller 52 may be stopped so as not to slip.
5, the leading edge of the sheet becomes unstable, and a cause of oblique feeding is created. Further, if the conveyance is started in a state where the leading end of the sheet P is not securely held by the nip portion of the registration roller 55, there is a fear that the conveyance timing is delayed or a conveyance failure (mis-conveyance) occurs.

Therefore, in the feeding roller 52, the sheet cannot be stopped until the leading end of the sheet comes into contact with the registration roller 55 and the sheet P is bent as desired, and as a result, an abnormal sound is generated due to resonance as described above. The method for solving the problem is not disclosed in the above-described publication in the sheet feeding technique.

The present invention has been made in view of the above-described problems, and it is possible to eliminate the above-described abnormal sound caused by the continuous feeding of the feed roller and the occurrence of a slip phenomenon with a sheet. It is an object of the present invention to provide a sheet feeding device that can perform the above-described operations.

It is another object of the present invention to provide a sheet feeding apparatus which eliminates the above-mentioned points and also eliminates noise due to bouncing of the sheet rear end. .

[0019]

According to the first aspect of the present invention, there is provided a sheet feeding apparatus according to the present invention.
A feeding roller is provided, and a feeding unit is provided that continuously drives and controls the feeding roller in a state where the leading edge of the fed sheet is stopped, and starts feeding the temporarily stopped sheet to a target position. In the sheet feeding apparatus, a guide for guiding a sheet fed through the feeding roller to the conveying unit is provided, and the sheet is guided so as to bridge between the guide and the feeding roller. A second guide is further provided.

According to the sheet feeding apparatus having such a configuration, the sheet is temporarily stopped by the conveying means for conveying the sheet to the target position via the feeding roller, but is further stopped by the feeding roller. The sending operation is continued. For this reason, the leading end of the sheet is reliably brought into contact with the conveying means and aligned, so that the conveyance by the conveying means can be reliably started. Further, since the conveying means stops the oblique feeding or the like, the leading ends of the sheets are securely aligned, and the conveying failure such as the oblique feeding can be eliminated. At this time, the feeding roller slips with respect to the sheet, and the vibration at that time is transmitted to the sheet by the slip phenomenon. However, the sheet is guided by the second guide after being fed by the feeding roller and before being guided by the conveying means via the guide, and the area in contact with the guide increases.
Thereby, sheet vibration is suppressed. Therefore, the vibration noise generated when the sheet vibrates and comes into contact with the guide end that guides the sheet to the conveying means can be significantly reduced or eliminated. Thus, even if some space or the like is formed on the back surface of the seat, the occurrence of abnormal noise can be effectively prevented without causing resonance due to the air layer in the space.

According to a second aspect of the present invention, there is provided a sheet feeding apparatus having the above-mentioned configuration, wherein a portion for guiding a sheet of the second guide is provided. Are provided so as to be close to the above-mentioned guides, so that the lower portions of both guide surfaces are not formed in the space.

According to another aspect of the present invention, the second guide is formed in a shape along the guide surface of the guide. I do. With this configuration, when the sheet rear end passes through the feeding roller, the sheet is guided by the second guide, so that the sheet does not immediately come into contact with the guide, and the sound such as a collision sound due to the rebound of the sheet rear end. Occurrence can be prevented. And
When the guide surface of the second guide is provided along the guide surface of the guide when the sheet passes through the second guide and reaches the guide that guides the sheet to the conveying means, the collision by the trailing edge of the sheet at that time Sound can be greatly reduced, and it does not cause harsh noise.

On the other hand, a sheet feeding apparatus according to a fourth aspect of the present invention for achieving the above-mentioned object is provided with a feeding roller to temporarily stop a fed sheet and to start feeding when necessary. In a sheet feeding device provided between the feeding roller and the feeding means, a guide for guiding the sheet fed to the feeding means is provided for guiding the sheet to a nip portion of the feeding roller. A convex rib is provided between the elastic sheet or the feeding roller to prevent vibration transmitted to the sheet when the rotation of the feeding roller is continued while the sheet is stopped. And

According to the sheet feeding apparatus having such a configuration, the sheet fed by the feeding roller is stopped with its leading end aligned with the position of the conveying means. Then, when the feeding roller is continuously driven, a slip state occurs with respect to the stopped sheet, and the vibration at that time is transmitted to the stopped sheet. At this time, the vibration transmitted to the sheet from the nip portion of the feeding roller is suppressed by the convex rib contacting the sheet. Alternatively, the vibration of the sheet is absorbed by the deformation of the elastic sheet, and the vibration sound is eliminated without being transmitted to the sheet in contact with the guide tip.

In the sheet feeding apparatus having the above-mentioned configuration, according to the invention described in claim 5, the leading end of the elastic sheet or the sheet guide surface of the convex rib is provided.
It is characterized by being provided near the nip portion of the feed roller. With such a configuration, a large undulating state of the seat can be eliminated, vibration transmitted to the seat can be more effectively absorbed, and the effect of preventing generation of vibration noise can be enhanced.

Further, in the sheet feeding apparatus having the above-mentioned configuration, according to the invention, the second guide for guiding the sheet so as to bridge between the guide and the feeding roller. Is further provided. As described above, by providing the respective guides, it is possible to reliably guide the sheet to the conveying means, and at the same time, to reduce or eliminate the collision sound due to the rebound when the rear end of the sheet passes through the feeding roller. It becomes possible.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment suitable for a sheet feeding apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view for explaining the overall configuration of a sheet feeding apparatus according to the present invention, and is a view showing a first embodiment for eliminating abnormal noise. FIG. 2 is a configuration diagram showing the entire internal structure of an image forming apparatus including the sheet feeding apparatus shown in FIG. 1, particularly, a digital copying machine.

First, referring to FIG. 2, an image forming apparatus according to the present invention will be described. This image forming apparatus 1
This is a digital copier equipped with a laser printer. However, the present invention is not limited to a sheet feeding device in a digital copying machine, but can be generally applied to all feeding devices that feed a sheet to a required position. Examples of the image forming apparatus include an electrophotographic printer using a normal electrophotographic system, an inkjet printer that forms an image by ink jetting, a thermal printer that forms an image by thermal transfer, and the like, and a facsimile apparatus including these printers. There is. In these apparatuses, a sheet feeding apparatus of the present invention described below can be applied to a sheet feeding apparatus for feeding a sheet to a required position.

The main body of the digital copying machine 1 shown in FIG. 2 has a photoconductor 2 formed in a drum shape which is a recording medium having a photoconductive layer formed on the surface rotating in the direction of the arrow as shown in FIG. A charger 3 for uniformly charging the surface along the rotation direction, an exposure unit 4 for imagewise exposing the charged surface, a developing device 5 for developing an electrostatic latent image formed by exposure, and a sheet for developing the toner image And a cleaning device 7 for removing the residual toner after the transfer are arranged to face each other in this order.

The exposing section 4 for exposing the surface of the photosensitive member 2 to image exposure irradiates a laser beam 9 to the surface of the photosensitive member 2 by a laser irradiation device 8. The laser irradiation device 8 drives the semiconductor laser ON / OFF in accordance with input image data, and the laser beam 9 is applied to another mirror and lens by the polygon mirror 10 as a polarizer in the rotation axis direction of the photoconductor 2. And so on. As a result, the laser beam 9 is applied to the surface of the photoconductor 2 uniformly charged by the charger 3.
Is irradiated, and an electrostatic latent image corresponding to the image is formed.

The electrostatic latent image formed on the photoreceptor 2 is visualized by a developing device 5 with toner, and the visualized toner image is transmitted through a sheet feeding system according to the present invention. The sheet is conveyed by a transfer device (or a transfer roller) 6 to transfer the sheet.

In order to irradiate the photoreceptor 2 with a light image by the laser beam 9 corresponding to the image data, a scanner 11 for optically reading the image of the original is provided at the upper part of the image forming apparatus 1. ing. The scanner 11 has a well-known structure, and includes a transparent platen 12 for placing the original with the image side down, a document cover 13 for pressing the original placed on the transparent platen 12 from above, a transparent cover An exposure lamp 14 for irradiating the image surface of the document from below the platen 12, a first reflecting mirror 15 for reflecting the reflected light from the document to a desired position, and a reflecting light from the reflecting mirror 15 to an image forming lens side. A pair of second and third reflecting mirrors 16 and 17 for reflecting light, an image forming lens 18 for forming an image on a light receiving surface of a CCD which is a reading element for converting an image of light by reflected light into an electric signal, and a reading element. And a CCD 19.

The first reflecting mirror 15 and the exposure lamp 1
4 are provided on the same scanning means, and the transparent platen 1
2 is driven in the direction of the arrow. In contrast to this scanning means, the second scanning means supporting the second and third reflection mirrors 16 and 17 is moved at a traveling speed of 1 by the scanning means.
The vehicle is driven at a speed of / 2. As a result, the image of the original is sequentially formed on the light receiving surface of the CCD 19. Accordingly, electric signals corresponding to the image of the original are sequentially output from the CCD 19 as image data.

The image data is sent to an image processing circuit (not shown), and the image forming apparatus 1 described above irradiates the surface of the photosensitive member 2 with a laser beam 9 to obtain a corresponding image. Is processed as data. The data after this processing is finally sent to the laser irradiation device 8 as image data.

According to the above description, the image forming apparatus functions as the digital copying machine 1, but it can also function as a printer. That is, the digital copying machine 1 receives image data from another image input device (a facsimile device, a personal computer, another scanner, etc.) via a communication line, and transmits the image data to the digital copying machine 11 having the above-described configuration. A desired image can be arbitrarily obtained by being processed as image data that can be formed and sent to the laser irradiation device 8.

Next, in the above-described digital copying machine 1,
A sheet conveying system for transferring an image formed on the surface of the photoconductor 2, that is, a toner image, to a sheet and finally outputting the image to the outside of the image forming apparatus 1 will be described. The sheet transport system feeds the sheet to a transfer position, which is a target position facing the transfer device 6 as described above, and after transfer, is separated from the photoreceptor 2 and is connected to the upper portion of the image forming apparatus 1 via a heat fixing device. This is for transporting and discharging sheets one by one to a discharge tray provided in the printer.

Therefore, a sheet feeding system according to the present invention for feeding a sheet to a transfer position will be described. For this purpose, the sheet feeding system is provided with a registration roller 20 for feeding in synchronization with the rotation of the photoconductor 2. The sheet feeding device according to the present invention for feeding a sheet to the registration rollers 20 is provided further upstream (upstream side) of the transfer position.

The sheet feeding device includes an automatic feeding device 21 provided at a lower portion of the main body of the image forming apparatus 1, that is, an upstream side of the registration roller 20, and a manual feeder provided at a right side of the main body of the image forming device 1. And a sheet feeding device 22 of the present invention.

The automatic feeding device 2 which is the above-mentioned sheet feeding device
1 has, for example, a paper feed cassette or a tray 21a that can be pulled out to the near side in the drawing, and is configured to store sheets of a predetermined size. For this reason, a loading plate 21b for loading sheets to be accommodated in the cassette is provided. The mounting plate 21b is rotatably supported on a side opposite to a position facing the paper feed roller 21c, and is rotated so as to be constantly urged upward by urging means such as a spring (not shown). Have been moved.
Separating claws are provided at both corners of the leading edge of the mounting plate 21b on the sheet feeding side. The separating claws regulate the floating of the sheet on the mounting plate 21b, and the uppermost position of the sheet is always constant. Is held at the height.

In the non-sheet feeding state, the sheet feeding roller 21c
As shown in FIG. 2, the string portion faces the mounting plate 21b, and the sheet cassette 21a can be pulled out in this state. When the paper feed state is reached, the arc portion of the paper feed roller 21c comes into contact with the uppermost sheet on the mounting plate 21b, the mounting plate 21b is pressed down, and the uppermost sheet is moved by the arc of the paper feed roller 21c. The sheet is gradually fed at the portion, and one sheet is fed with both corners of the uppermost sheet over the separation claw.

Further, in order to feed a sheet fed by means other than the paper feed roller 21c to the position of the registration roller 20, the sheet feeding device 22 for manual feeding, which is a sheet feeding device according to the present invention, is provided. Automatic paper feed unit 21
And are provided so as to face. The manual sheet feeding device 22 is provided with a guide path, which will be described later, so that the sheet fed from the sheet feeding unit 21 and the registration roller 20 merge.

A sheet detector 23 is disposed in front of the registration roller 20, that is, upstream of the registration roller 20, and the registration roller 20 is provided in accordance with the detection result of the sheet detector 23.
Is temporarily stopped. That is, when the sheet P is detected by the sheet detector 23, the registration roller 20 is controlled to stop while holding the leading end of the sheet P. Then, control is performed so that feeding of the sheet to the transfer position is restarted at a timing when the leading edge of the toner image formed on the photoconductor 2 matches the leading edge of the sheet.

As described above, the sheet feeding and the feeding control to the transfer position facing the photosensitive member 2 are performed.
The toner image formed on the photoconductor 2 is transferred onto the sheet P by the operation of the transfer device 6. After this transfer,
The sheet P is separated from the photoreceptor 2, and a heat fixing roller 24 constituting a fixing device disposed at an upper portion in FIG.
Transported to The heat-fixing roller 24 also has a conventionally well-known configuration, in which the roller facing the toner image surface of the sheet is a heat roller that is maintained at a fixing temperature, and pressure is applied to press the sheet against the heat roller. And a roller.

The toner image carried on the sheet passing through the heat fixing roller 24 is melted and fixed. Then, finally, the sheet is guided along a discharge path on a discharge tray 26 disposed outside the image forming apparatus 1 and is discharged through a discharge roller 25 positioned at a discharge port. Further, sheet detectors 27 and 28 for detecting the feeding state of the conveyed sheet are provided corresponding to the positions of the heat fixing roller 24 and the discharge roller 25, respectively.

The automatic feeding device 21 constituting the above-described sheet feeding device is as described above, and the other sheet feeding device 22 for manual feeding will be described below. The manual feeding dedicated feeding device 22 includes a sheet feeding port 30 provided on the right side of the main body of the image forming apparatus 1 in FIG. Feeding table 3 for guiding the sheet to a feeding roller 31 for feeding the sheet to
Two.

The manually inserted sheet is guided to the feed roller 31 along the feed table 32, and the feed roller 31
The sheet is guided to the merging section 29 and sent to the registration roller 20 in the same manner as the sheet fed from the sheet feeding cassette 21a through the sheet feeding roller 21a.

The guide path 29a provided so as to communicate with the lower part of the main body of the image forming apparatus 1, particularly the position of the registration roller 20, is fed from the above-mentioned sheet feeding cassette 21a or the sheet feeding device 22 for manual feeding. This is a path that communicates with a merging section 29 that merges the sheets that are received. The guide path 29a is configured such that a unitized feeding device having the same configuration as the automatic sheet feeding device 21 is provided at a lower portion of the main body of the image forming apparatus 1 so that it can be appropriately mounted. As a result, sheet feeding can be performed in the same manner from another sheet feeding device mounted at the lower portion. Therefore, a communication guide path 29 a is provided below the image forming apparatus 1.

(First Embodiment) In the configuration of the digital copying machine 1 provided with the sheet feeding apparatus as described above, the abnormal sound due to the vibration of the sheet according to the present invention is eliminated according to the drawing shown in FIG. An optimal configuration of the first embodiment of the sheet feeding apparatus will be described.

FIG. 1 shows the details of the above-described sheet feeding device 22 dedicated to manual feeding. Sheet feeding device 22
Is transferred to a merging section 29 which leads to the registration roller 20.
The sheets P inserted one by one are fed. The registration roller 20 is provided with the above-described merging section 29 where the above-described guide path from the automatic feeding device 21 and the sheet guide path from the sheet feeding device 22 dedicated to manual feeding merge. A guide 33 forming a sheet guide path from the automatic feeding device 21, a guide 34 forming a sheet guide path from the sheet feeding device 22, and a sheet from a lower portion (not shown) A guide 33a using the opposite surface of the guide 33 constituting the guide path 29a is provided.

In particular, the guide 34 is provided to guide the sheet P fed via the feed roller 32 constituting the sheet feeder 22 to the junction 29. It is necessary to guide the sheet so as to be in the direction of conveyance by the registration rollers 20, that is, in the vertical direction here. For this reason, the guide 34 is provided in a state where the guide surface (the surface with which the sheet P contacts) at the front end approaches in the vertical direction.
Guide 33a of merging section 29 due to rebound of the sheet rear end
The noise at the time of collision is reduced or eliminated.

On the other hand, when the sheet is fed by the sheet feeding device 22 dedicated to manual feeding, the sheet is fed in a substantially horizontal state as shown in FIG. After the sheet P has passed the feed roller 31, the sheet P attempts to return to the posture such that the rear end thereof matches the guide direction of the front end that has been previously fed vertically. Due to the restoring force when returning to that posture, the rear end of the sheet collides with the guide 34 provided with the guide surface in the direction of guiding to the registration roller 20. Loud noise, that is, noise is generated by the collision.

This is because the guide 34 is
, The sheet guide surface is formed in a direction along the conveying direction, and a large noise is generated due to a collision caused by the rebound of the sheet rear end when the sheet is fed from a direction substantially perpendicular to the sheet guide surface.

In order to solve this problem, a second guide 35 for guiding the sheet to a guide 34 via a feed roller 31 is provided so as to extend further than the feed table 32. The upper surface of the second guide is a guide surface that supports and guides the sheet, and is located slightly below the nip portion of the feeding roller 31 (the pressure contact portion between the rollers).

The second guide bridges between the feeding table 32 and the guide 34 for guiding the sheet to the registration rollers 20. The second guide is guided to the guide 34 while supporting the rear surface of the sheet P. I do. The guide surface of the guide 34 is provided in an upwardly inclined state so as to communicate with the guide surface of the feeding table 32. Therefore, even when the rear end of the sheet P passes through the feeding roller 31, the rear end of the sheet P is guided upward by the second guide 35 as it is, and is guided along the guide 34 approaching the vertical direction. Thereby, the guide 34 is rebounded by the rear end of the sheet P.
The collision sound when colliding with the guide surface is reduced or eliminated.

The feeding roller 31 constituting the sheet feeding device 22 is as described in the prior art, and comprises a pair of rollers, the upper portion being a driving roller 31a and the lower portion being a pressing roller 31b pressed against the roller 31b. And a pair of rollers. And the pressure roller 31b is
It is urged toward the upper drive roller 31a by a spring 36, which is an urging means, and is pressed against it. Then, the manually inserted sheet P is nipped and fed between the rollers 31a and 31b.

Hereinafter, the operation and effect of the second guide 35 unique to the present invention, which is different from the above-described second guide 35, which is different from the noise reduction due to the collision due to the rebound of the sheet, will be described.

One sheet P inserted through the paper feed port 30 is supported by the guide surface of the feed table 32, and is guided to the feed roller 31 along the sheet. At this time, the sheet P to be inserted is detected by a sheet detector (not shown) (not shown) just before the feed roller 31, and the rotation of the feed roller 31 is started. Due to this rotation, the inserted sheet P is nipped at its leading end and guided and sent to the registration roller 20 by the guide 34 and the like.

When the sheet P is fed by the feed roller 31, the leading end thereof is guided to the junction 29 via the guide 34 and is sent to the registration roller 22. Then, just before the leading end is sent to the registration roller 20, the sheet is detected by a sheet detector 23 as shown in FIG. The registration roller 20 starts the conveyance of the sheet P to the transfer position of the sheet P in accordance with the rotation of the photoconductor 2, and temporarily stops the fed sheet P.
In a non-driving state.

For this reason, the leading end of the sheet P is fed into the nip portion (the pressure contact portion between the pair of rollers) of the registration roller 20 and stopped in that position. At this time, the feeding roller 31 continues to rotate, and the sheet P has its leading edge aligned at the nip portion of the registration roller 20. Therefore, the leading edge of the sheet P is aligned at the nip so that the oblique feeding state of the sheet P is eliminated, and the registration rollers 2
The oblique feed after 0 is also eliminated.

Further, the feeding roller 31 is connected to the sheet detector 2.
Even if the leading edge of the sheet P is detected at 3, the leading edge of the sheet P is aligned with the registration roller 20 and stopped when sufficient bending (curving) of the sheet P is formed. Therefore, the rotation of the feed roller 31 is stopped a predetermined time after the sheet detector 23 detects the leading edge of the sheet. Alternatively, since the sheet is rotated again in accordance with the rotation of the registration roller 20, the rotation of the feed roller 31 may be continued and driven.

When the leading end of the sheet P is stopped by the registration roller 20 and the feeding roller 31 is continuously rotated, the feeding of the stopped sheet P by the feeding roller 31 is in a slip state. Therefore, the sheet P vibrates due to a phenomenon caused by slip. In this case, the sheet P is nipped and maintained between the registration roller 20 and the feed roller 31, and is in contact with the guide 34, so that a sound is generated by vibration.

However, according to the sheet feeding device 22 according to the first embodiment of the present invention, the sheet P is
And a second guide for supporting and guiding the sheet P between the
Guide 35 is provided. Therefore, the back surface of the sheet P further contacts and is supported by the second guide 35. Thereby, the contact area between the guide 34 and the second guide 35 that come into contact with each other due to the vibration of the sheet P due to the slip phenomenon increases, and the vibration of the sheet is suppressed. Therefore, the vibration noise generated when the vibrating sheet P comes into contact with the guide 34, particularly at the tip, is greatly reduced or eliminated.

Further, even if a space 37 is formed between the feeding roller 31 and the guide 34, the vibration sound is not generated as described above, so that resonance occurs in the air layer of the space 37. Disappears. Therefore, the result is that abnormal noise caused by resonance can be eliminated.

In other words, by providing the second guide 35, the sheet guide path is bridged between the feed roller 31 and the guide 34, and the contact area with the sheet P is increased. Vibration caused by the slip phenomenon can be suppressed, so that vibration noise when contacting the guide 34 can be eliminated. That is, the vibration of the sheet P is absorbed by the contacted second guide, and the vibration noise generated when the sheet P comes into contact with the distal end of the guide 34 due to the vibration can be eliminated.

When the conveyance of the sheet P is started by the registration roller 20 at the time when the toner image is transferred to the sheet P, the rear end of the sheet P
Pass 1 At this time, the rear end of the sheet is guided by the second guide 35 and further guided to the guide 34. Therefore, the sound of collision with the guide 34 due to the rebound of the rear end of the sheet is also eliminated.

Here, in FIG. 1, the second guide 3
5 and guide 34 for guiding to registration roller 20
And are provided so as to be slightly separated from each other. for that reason,
A space 3 is formed in a lower portion surrounded by the guide 34 and the second guide 34.
7 is formed. Guide 34 in the air layer of the space 37
It is conceivable that the vibration sound due to the slip phenomenon of the sheet P contacting the sheet resonates. However, the provision of the second guide 35 increases the contact area of the sheet P with the guide surface, and suppresses the vibration transmitted to the sheet P. Therefore, the vibration noise and the like are scarce, and the problem of resonance and the like also occurs. Absent.

In this case, in order to solve problems such as resonance,
As shown in FIG. 3, the guide 34 and the space 37 communicating with the back surface of the sheet P so that the tip of the second guide 35 is close to the guide 37.
Is not formed. This eliminates the problem due to resonance. That is, the problem caused by the resonance can be solved without the direct space 37 existing below the sheet P.

As described above, in the sheet feeding device 22 according to the present invention, the vibration noise caused by the slip phenomenon by the feeding roller 31 for feeding the sheet to the registration roller 20 can be effectively eliminated. In addition, the collision sound caused by the jumping of the rear end of the sheet P can also be eliminated. In the configuration for that purpose, the object of the present invention can be achieved by a simple configuration in which the second guide is simply provided between the feeding roller 31 and the guide 34 for feeding the registration roller 20, and the operation as described above is achieved. The effect can be obtained.

(Second Embodiment of the Present Invention) Next, a second embodiment of the present invention will be described with reference to FIGS. In the first embodiment described above, the sheet P is stopped by the registration roller 20, and the vibration sound generated by the slip phenomenon due to the continuous operation of the feeding roller 31 is generated by the feeding roller 31. Reduced by increasing the contact area with the guiding guide,
Or try to eliminate it. In this embodiment, in particular, the micro vibration of the sheet P due to the slip phenomenon is absorbed in the vicinity of the nip portion of the feeding roller 31, so that the vibration noise caused by the vibration is eliminated.

Referring to FIG. 4, FIG.
Alternatively, a major difference from FIG. 3 is the convex rib 38 provided near the position of the contact portion of the feeding roller 31. Other configurations are the same as those in FIGS. 1 and 3.

The above-mentioned convex ribs 38 are provided on the feeding roller 31.
Are provided before and after the pressure contact portions of the upper and lower rollers 31a and 31b, that is, from upstream to downstream of the nip portion. On the upstream side of the rib 38, in order to prevent a sheet to be inserted from being caught, the rib 38 is formed so as to be gently inclined upward so as to be guided to a nip portion of the feeding rollers 31a and 31b.

The sheet guide surface of the rib 38 is located at a position substantially equal to or lower than the nip portion of the feed roller 31. Moreover, the ribs 38 are arranged so as to be located between the positions where the feed rollers 31a and 31b are not provided as shown in FIG.

In the above configuration, the feeding roller 3
The sheet P sent to the registration roller 20 via the first roller 1 is stopped when the leading end thereof is aligned with the registration roller 20 and the feeding roller 31 is continuously driven. And convey the vibration. At this time, the sheet P sandwiched between the feeding rollers 31a and 31b
As shown in FIG. 5 (b), near the holding portion, it comes into contact with the guide surface of the convex rib 38, and acts to reduce the vibration due to the slip phenomenon, that is, to cancel the vibration. as a result,
The sheet P vibrates, and the vibration sound at the portion in contact with a part of the guide 34 is eliminated.

That is, the above-mentioned convex rib 38 is formed as shown in FIG.
Between the feed rollers 31 and as shown in FIG.
Since the sheet P is provided so as to extend from the upstream to the downstream of the nip portion between the rollers 31a and 31b, the vibration of the sheet P sandwiched between the rollers 31a and 31b is suppressed by the contacting rib 38, and the vibration noise caused thereby is eliminated. it can.

Further, the guide surface of the convex rib 38 is shown in FIG.
(A) and as shown in FIG. 4, the feed rollers 31a, 31
Since it is slightly lower than or the same as the nip portion b, it is possible to prevent the sheet P from waving due to vibration, thereby promoting the effect of eliminating vibration noise. That is, when the guide surface (the surface that comes into contact with the sheet P) of the convex rib 38 is too low or protrudes too much from the nip portion, the waving becomes large, the sheet P vibrates greatly, and the vibration sound at that time is large. Become. However, by providing the above-described convex rib 38 of the present invention, such a problem can be solved.

(Alternative Embodiment According to Second Embodiment) In the second embodiment described above, when the vibration caused by the slip phenomenon by the feed roller 31 is transmitted to the sheet P, the vibration of the sheet is supplied. The problem is solved by providing a convex rib 38 at the position of the nip portion of the feed roller 31. As described above, another configuration for reducing or eliminating the transmission of vibration to the sheet P may have a configuration as shown in FIG.

The sheet feeding device shown in FIG. 6 has an elastic sheet 39 which is elastically deformed. This elastic sheet 3
Reference numeral 9 is provided at a position upstream of the feed roller 31 so as to guide the sheet P guided along the sheet feed table 32 to the nip portion of the feed roller 31.

One end of the elastic sheet 39 is fixed to the feed table 32 side, and the free end side of the other end is provided on the feed roller 31 near the nip portion. Therefore, when the sheet P is inserted along the feeding table 32, the sheet P is guided to the feeding roller 31 by the elastic sheet 39. Then, the sheet P is sent to the registration roller 20 by the rotation of the feeding roller 31, and the leading end is stopped by the registration roller 20.

At this time, since the feed roller 31 continues to feed the sheet P, the sheet P vibrates due to a slip phenomenon. Since the vibration transmitted to the sheet P via the feed roller 31 is absorbed by the elastic deformation of the elastic sheet 39, no vibration noise is generated by the contact with the guide 34. As a result, generation of vibration noise due to contact between the sheet P and the guide 34 due to vibration, and abnormal noise thereof are prevented.

The elastic sheet 39 may be provided such that its tip extends downstream of the nip portion of the feed roller 31. Therefore, as shown in FIG. 7, an extension 39a of the elastic sheet 39 may be provided while the feed roller 31 is not present, and the extension 39a may be located downstream of the nip. In this way, the vibration transmitted to the sheet P via the nip portion of the feed roller 31 due to the slip phenomenon is more effectively absorbed by the elastic sheet 39 by elastic deformation, and abnormal noise due to the vibration is reduced. The prevention effect increases.

As described above, this is a sheet feeding apparatus having a configuration in which the sheet P is fed into the registration roller 20 once stopped via the feeding roller 31, and the feeding roller 31 is continuously driven. Needless to say, the present invention can be applied to all sheet feeding apparatuses having such a configuration. Although the sheet feeding device 22 described above is a sheet feeding device dedicated to manual feeding, it can be similarly implemented in an automatic feeding method, and has the same effect.

In the second embodiment of the present invention,
The convex ribs 38 and the elastic sheet 39 are provided to effectively suppress or absorb the vibration transmitted to the sheet P. Therefore, without providing the second guide 35 as shown in FIGS. 4 and 6, it is possible to prevent the generation of the abnormal sound due to the vibration of the sheet P. Therefore, the second guide 35 can be omitted. However, by providing the second guide 35, as described above, the conveyance of the sheet P by the registration roller 20 causes the rear end of the sheet P to collide with the guide 34 due to rebound when the sheet P passes through the feeding roller 31 as described above. Very effective when the sound is harsh. In addition, the effect of preventing vibration is further enhanced, and the effect of preventing occurrence of abnormal sound is further increased.

[0083]

According to the sheet feeding apparatus of the present invention, the guide provided between the feeding roller and the registration roller is provided with the second guide which bridges between the guide and the feeding roller. With this configuration, even if vibration generated by the slip phenomenon due to the continuous operation of the feeding roller is transmitted to the sheet P, it is possible to prevent the abnormal sound due to the vibration by increasing the contact area between the sheet and the second guide. it can.

Further, by bringing the second guide and the guide for guiding the sheet to the registration roller close to each other, the space formed is eliminated, and the effect of preventing the generation of abnormal sound due to the resonance of the vibration sound due to the air layer is enhanced. .

Further, by providing a convex rib or an elastic sheet near the nip portion of the feeding roller, vibration to the sheet P transmitted from the nip portion to the feeding roller can be prevented or absorbed, so that vibration noise can be reduced. The occurrence can be prevented. In this case, by arranging the guide surface of the rib near the nip portion, it is possible to prevent the sheet from waving, and it is possible to efficiently prevent the generation of vibration noise.

By providing the second guide, noise due to the rebound of the sheet rear end can be prevented, and by providing the sheet guide surface along the path for guiding the sheet to the registration roller, the rear of the sheet can be prevented. The noise of bouncing when the end comes into contact with the guide can also be eliminated.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an example of a first embodiment of a sheet feeding device according to the present invention.

FIG. 2 is a configuration diagram illustrating a schematic configuration of a digital copying machine which is an image forming apparatus including the sheet feeding device in FIG. 1;

FIG. 3 is a cross-sectional view of the sheet feeding device according to a first embodiment of the present invention for explaining another mode of suppressing occurrence of abnormal noise in the sheet feeding device.

FIG. 4 is a cross-sectional view of a sheet feeding device according to a second embodiment of the present invention for explaining the configuration of the sheet feeding device;

5 is a cross-sectional view illustrating a configuration of a convex rib provided on a second guide in a nip portion of a feeding roller included in the sheet feeding apparatus illustrated in FIG.

FIG. 6 is a cross-sectional view illustrating another configuration of the sheet feeding apparatus according to the second embodiment of the present invention which prevents vibration of a sheet.

FIG. 7 is a perspective view showing an arrangement state of an elastic sheet positioned near a nip portion of a feeding roller in the sheet feeding device in FIG. 6;

FIG. 8 is a side sectional view showing an example of a conventional sheet feeding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Digital copying machine (image forming apparatus) 2 Photoreceptor 5 Developing device 6 Transfer device (transfer part) 20 Registration roller 21 Automatic paper feeding part 22 Sheet feeding device for manual feeding 30 Paper feeding port 31 Feeding roller 32 Feeding stand 34 guide 35 second guide 37 space 38 convex rib 39 elastic sheet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Hori 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Japan Inside Sharp Corporation (72) Inventor Shinji Oishi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Yasushi Matsutomo 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Inventor Mikaru Morita 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation F Terms (reference) 2H072 BA03 BA06 CA01 3F101 FA03 FB01 FC05 FD04 FE06 LA01 LB03 3F102 AA02 AB01 BA01 BA08 BB02 EA03

Claims (6)

[Claims] 1. A feeding roller is provided, and while the leading end of a fed sheet is stopped, the driving of the feeding roller is continuously controlled to start transporting the temporarily stopped sheet to a target position. A sheet feeding device including a conveying unit that guides a sheet fed through the feeding roller to the conveying unit, and bridges between the guide and the feeding roller. The sheet feeder further includes a second guide for guiding the sheet. 2. The second guide according to claim 1, wherein a portion for guiding the sheet is provided so as to be close to the guide, and no space is formed below the guide surfaces of the two guides. The sheet feeding device as described in the above. 3. The sheet feeding device according to claim 1, wherein the second guide is formed in a shape along a guide surface of the guide. 4. A guide for guiding a sheet to be fed to a conveying means which is provided with a feeding roller, temporarily stops the fed sheet, and starts conveying when necessary, comprises a feeding roller and a conveying means. And a sheet feeding device provided between the feeding roller, an elastic sheet for guiding the sheet to the nip portion of the feeding roller, or a convex rib is provided between the feeding rollers,
A sheet feeding device configured to prevent vibration transmitted to a sheet when the rotation of a feeding roller is continued while the sheet is stopped. 5. The sheet feeding device according to claim 4, wherein a tip of the elastic sheet or a sheet guide surface of the convex rib is provided near a nip portion of the feeding roller. Feeder. 6. The sheet feeding apparatus according to claim 4, further comprising a second guide for guiding a sheet so as to bridge between said guide and said feeding roller.