JP2002046883A - Sheet feeding device, picture image formation device furnished with it or picture image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and precisely set overlapping quantity without spoiling an advantage of a sinking comb type feeding mechanism, to improve and stabilize separating performance of a sheet and to easily carry out maintenance work at the time of durable longevity, etc., in inexpensive constitution. SOLUTION: A sheet carrier means has a first rotating drive shaft 9 to be rotationally driven in a delivering direction and a plural number of carrier rollers 2 to be put on the first rotating drive shaft, a sheet separation means has a second rotating drive shaft 10 to be rotationally driven in the opposite direction of the delivering direction and a plural number of separation rollers 1 to be put on the second rotating drive shaft, each of the separation rollers 1a faces against a portion where each of the carrier rollers 2a is not arranged and is arranged to overlap with no contact against each of the carrier rollers 2a, it is formed of an elastic body of lower hardness than each of the carrier rollers 2a, and each of the carrier rollers 2a is applied with chamfering on both end sides of it.

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 for feeding a sheet to an apparatus main body, and an image forming apparatus or an image reading apparatus having the same.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction peripheral thereof, an image forming section for forming an image on a sheet and an image reading section for reading an image of a document are generally provided. In addition, a sheet feeding device for feeding a sheet to the image forming unit and the image reading unit is provided.

Here, a general configuration of a sheet feeding apparatus includes, for example, sheet stacking means such as a tray or a cassette for stacking and storing a plurality of sheets, and a sheet for feeding sheets stacked on the sheet stacking means. Feeding means. Then, the sheets stacked and stored in the sheet stacking unit are sequentially fed out to the image forming unit side by the sheet feeding unit, and when a plurality of sheets are fed out at this time, they are separated into one sheet, Only the upper or lowermost sheet is sent to the image forming unit.

[0004] Here, as an example of the configuration of the sheet feeding means, a pick-up roller for feeding out the sheet by contacting the uppermost surface (or lowermost surface) of the sheet stacked on the sheet stacking means, and a downstream side of the pick-up roller. A transport roller located at a position opposite to the transport roller,
Are known. In this type of sheet feeding means, during sheet feeding, the pickup roller and the conveyance roller are driven to rotate in the sheet conveyance direction, and the separation roller is given a rotational torque in the direction opposite to the sheet conveyance direction. Even when a plurality of sheets are fed out by the pickup roller, the sheet abutting on the separation roller is returned to the sheet stacking means side, and only one sheet abutting on the transport roller is transported downstream. It has become so.

In recent image forming apparatuses, the speed of image forming processing by the image forming unit and the so-called throughput during continuous printing have been improved. Higher sheet feeding speed has been required. In recent years, in addition to plain paper such as copy paper, various types of sheets used as each product specification of the image forming apparatus include, for example, special thin paper, stiff cardboard, and special OHP film. A variety of materials have been introduced. Under such circumstances, it is becoming difficult for the sheet feeding apparatus to ensure the sheet separating performance of the sheet feeding means.

Incidentally, as a configuration example of a sheet feeding means having a good sheet separating performance in a conventional sheet feeding apparatus, there is a type called a so-called comb separation mechanism. This comb tooth separation mechanism is such that a plurality of the above-described conveying rollers and the separating rollers are arranged side by side at predetermined intervals with respect to the conveying roller axis and the separating roller axis, and the plurality of conveying rollers and the plurality of separating rollers are separated. The roller has a configuration in which the rollers are arranged so as to be in non-contact with each other and to overlap each other.

In a sheet feeding apparatus provided with such a tooth separating mechanism, a group of conveying rollers as conveying means for conveying a sheet and a group of separating rollers as separating means for separating a sheet do not directly contact each other. As a result, the abrasion generated in each roller is reduced, the separation performance can be maintained for a long time, and the sheet passing therethrough is nipped and conveyed by each roller group, so that the cross section in the sheet traveling direction is There is an advantage that the shape becomes substantially corrugated, the stiffness becomes strong, and sheet jamming hardly occurs.

In a sheet feeding apparatus provided with a comb-separating mechanism, a group of conveying rollers rotating in the conveying direction and a group of separating rollers rotating in the direction opposite to the conveying direction do not come into direct contact with each other. There is an advantage that the driving force of a driving motor or the like for driving each roller can be reduced. Further, since the transport roller group and the separation roller group do not come into contact with each other, there is no abnormal noise called so-called squeal which may occur when the two rollers come into contact with each other. In addition, in this type of sheet feeding device, by defining the distance between the transport roller shaft and the separation roller shaft, the overlap amount between each transport roller and each separation roller can be defined, so that the overlap amount can be easily determined. There was an advantage that could be guaranteed.

Conventionally, in a sheet feeding apparatus having such a tooth separating mechanism, rubber materials having similar properties have been used for each of the conveying rollers and each of the separating rollers. Once the amount of overlap was set and the feeding conditions were determined, extremely good separation stability with respect to the sheet was obtained. However, when separating a sheet having high rigidity such as thick paper, the hardness of each transport roller and each separation roller becomes relatively high, and the transport resistance at the time of contact with the sheet increases, so that the driving In some cases, a load on a motor or the like becomes large and a feeding failure such as a sheet jam occurs.

In order to cope with this problem, in a sheet feeding apparatus, as shown in FIGS. 10 and 11, a comb separating mechanism is constituted by an endless belt stretched on two axes instead of a separating roller. Appeared. That is, according to the comb separation mechanism of the belt separation method using the separation belt 101 instead of the separation roller, even if the overlap amount with the conveyance roller 102 is the same, the deformation of the sheet due to the overlap is prevented. Since the sheet can be absorbed by the separation belt 101, the setting can be made such that the contact with the sheet is soft. Also, by using the separation belt 101, the sheet can be contacted over a wide area in the transport direction, so that the surface pressure is reduced and the transport resistance can be reduced.

Hereinafter, the conventional sheet feeding apparatus of the belt separation type will be described in detail with reference to FIGS. 10 and 11. FIG.

In FIG. 10, reference numeral 101 denotes a separation belt as a separating unit in a conventional sheet feeding apparatus, 102 denotes a conveying roller as a conveying unit, and 103 denotes a pickup roller as a feeding unit.

The pickup roller 103 is configured to repeatedly move up and down in the direction of the arrow in FIG. 10 every time one sheet is conveyed by a lifting mechanism (not shown). Also,
Each of the feeding roller 102 and the separation belt 101 is the same as in FIG.
As shown in FIG. 1, over the width direction of the conveyed sheet,
A plurality of rollers are arranged side by side at a predetermined interval, and each roller and each belt are arranged so as to be opposed to each other so as not to directly contact each other while overlapping by a predetermined amount.

In this conventional belt-separated sheet feeding apparatus, the sheets S stacked and supported on a sheet supporting portion composed of a tray or the like (not shown) are moved downstream (right side in FIG. 10) by the rotation of the pickup roller 103. The sheet is fed out and conveyed to the conveying roller 102 and the separation belt 101. Here, when the sheet is sufficiently conveyed to the downstream side by the conveying roller 102 and the separation belt 101, the pickup roller 103 is retracted upward by the elevating mechanism so that the sheet is not fed more than necessary. .

Each belt constituting the separation belt 101 is
As shown in FIG. 11, it is disposed between the transport rollers 102 and constantly rotates in a direction opposite to the sheet transport direction. When a plurality of sheets are fed to the nip portion between the transport roller 102 and the separation belt 101 by the rotation of the pickup roller 103, the uppermost sheet is transported downstream by the transport roller 102, and the other sheets are transported. The separation belt 101 functions to return to the sheet support portion.

The sheets S separated one by one by the action of the conveying roller 102 and the separation belt 101 are fed to the outside from the sheet feeding device, and further conveyed to the downstream image forming section.

According to the sheet feeding apparatus provided with such a belt-separating type comb-separating mechanism, similarly to the comb-separating mechanism in which both the conveying means and the separating means are constituted by rollers,
Since the conveying means and the separating means are not in contact with each other, there are various similar advantages. That is, since the transport roller 102 rotating in the sheet transport direction and the separation belt 101 rotating in the opposite direction to the sheet transport direction do not come into direct contact with each other, the driving force of a drive motor or the like for driving them is reduced. Is possible, and there is no unusual noise called so-called squealing caused by contact between the two. Further, the abrasion of the transport roller 102 and the separation belt 101 is small, and the separation performance can be maintained for a long period of time. The sheet fed thereby has a gentle cross-sectional shape when viewed from the traveling direction, and the seat becomes strong. Furthermore, this waveform shape can also be expected to have a separating effect when a plurality of sheets are fed out, which contributes to avoiding sheet jams.

Also, unlike the comb tooth separating mechanism in which both the conveying means and the separating means are formed by rollers, the separating means is formed by an endless belt instead of a roller, and an overlapping area is formed between the pulley and the pulley for passing the endless belt. When the rigidity of the sheet is small, the overlap amount is maintained, and when the rigidity of the sheet is large, the separation belt 101 operates so as to escape and reduce the overlap amount. It acts so that the pressing force of the sheet by the roller 102 and the separation belt 101 is kept constant. This makes it possible to stabilize the conveying force of the conveying roller 102 and the returning force of the separation belt 101 irrespective of the rigidity of the sheet.

[0019]

In a conventional sheet feeding apparatus having such a belt-separating type comb-separating mechanism, the overlap amount δ between the conveying roller 102 and the separation belt 101 shown in FIG. Is a very important factor that determines the sheet separation performance, and by adjusting the value of δ, the feeding conditions such as the types of sheets that can be used have been determined.

However, in such a comb-separating mechanism of the belt separating type, since the conveying roller 102 and the separating belt 101 are overlapped in a non-contact manner,
It was very difficult to always keep the numerical value of the overlap amount δ at a predetermined amount. In particular, in the conventional example shown in FIGS. 10 and 11, when the overlap is formed in the slack portion of the separation belt 101, the separation belt 1
There was a problem that the amount of overlap changed during the rotation of No. 01, and the separation ability was not stable.

Further, in order to use a belt separating system for the comb tooth separating mechanism, it is necessary to dispose two pulley shafts and stretch the belt thereover. Therefore, there is also a problem that the configuration is complicated and the cost is increased.

Further, according to the conventional sheet feeding apparatus provided with the comb tooth separating mechanism regardless of the belt separating method,
Since the conveying roller and the separating means composed of a belt or a roller have a substantially rectangular cross-sectional shape, a characteristic deformation state of the sheet during sheet feeding (a state of a waveform when viewed from the traveling direction). In the case of, as shown in the enlarged view of FIG. 11, the contact pressure only at the roller end becomes large with respect to the corrugated sheet, and a stable loosening effect cannot be expected, and the overlap amount is adjusted. This has been an unstable factor in the feeding performance, such as narrowing the range condition, hindering the loosening effect by hindering the smooth wavy deformation of the sheet, and, in the worst case, jamming the sheet.

In addition, in the replacement maintenance work when the conveying means and the separating means have reached the end of their life due to the reduced friction coefficient due to the durable wear, in the case of the separating belt, it is difficult to remove the belt stretched on two axes. Furthermore, when a new belt is stretched, the amount of overlap with the transport roller must be strictly adjusted. Therefore, in addition to adjusting the distance between the pulleys in the belt pulley, the transport roller shaft with respect to the position of these two shafts is adjusted. Even a skilled service person took a very long time to make this adjustment, as the position had to be strictly adjusted, and was extremely difficult.

Also, in the separation device in which both the conveying means and the separating means are formed by rollers, a plurality of the conveying rollers and the separating rollers are fixedly provided on the drive shaft, respectively.
When replacing the transport roller and the separation roller whose service life has expired, it is necessary to remove each drive shaft. Since each drive shaft is rotatably mounted on the front and rear side plates of the sheet feeding device via bearings or the like, removal of these drive shafts requires a great deal of labor, and it is extremely difficult for a user to remove them. there were.

In view of this problem, a configuration has been devised in which only the feed separation unit is unitized so that it can be removed and replaced. However, the unit becomes large and has space for storing as a service part, and There were problems such as an increase in running costs.

An object of the present invention is to make it possible to easily and accurately set the overlap amount without impairing the advantages of the comb-type feeding mechanism, to improve and stabilize the sheet separation performance,
It is another object of the present invention to provide a sheet feeding apparatus which can be easily maintained at a low cost with a low-cost configuration and can perform maintenance work, and an image forming apparatus or an image reading apparatus having the same.

[0027]

A first configuration of a sheet feeding apparatus according to the present invention comprises a sheet supporting portion for stacking and supporting sheets, a feeding device for feeding the sheet from the sheet supporting portion, and a feeding device for feeding the sheet from the feeding device. Separating and conveying means for separating and conveying the sheet into one sheet,
In a sheet feeding device including a sheet conveying unit that contacts and conveys a sheet to be conveyed and a sheet separating unit that prevents the sheet from being conveyed when it comes into contact with a sheet other than the sheet to be conveyed, The conveying means has a first rotary drive shaft that is driven to rotate in the feed direction, and a plurality of transport rollers attached to the first rotary drive shaft, and the sheet separating means rotates in a direction opposite to the feed direction. A second rotation drive shaft to be driven, and a plurality of separation rollers attached to the second rotation drive shaft, each separation roller opposing a portion where each transport roller is not disposed, and It is arranged so as to overlap with the transport roller in a non-contact manner, and is formed of an elastic body having a lower hardness than each transport roller, and each transport roller is chamfered on both ends. .

A second configuration of the sheet feeding device according to the present invention is as follows.
The first configuration is characterized in that each separation roller has a cross-sectional shape that makes a curved contact with the sheet.

A third configuration of the sheet feeding apparatus according to the present invention is as follows.
In the first configuration, each transport roller has a cross-sectional shape having a plurality of contact surfaces with a sheet.

A fourth configuration of the sheet feeding device according to the present invention is as follows.
In any one of the first to third configurations, each transport roller is made of synthetic rubber.

A fifth configuration of the sheet feeding apparatus according to the present invention is as follows.
In any one of the first to fourth configurations, each separation roller is made of at least one of urethane, silicon, and sponge.

A sixth configuration of the sheet feeding apparatus according to the present invention is as follows.
In any one of the first to fifth configurations, the surface of each separation roller is formed of a material having a lower friction coefficient than the surface of the transport roller.

A seventh configuration of the sheet feeding apparatus according to the present invention is as follows.
The sixth configuration is characterized in that the surface of each separation roller is formed of a urethane material.

An eighth configuration of the sheet feeding apparatus according to the present invention is as follows.
In any one of the first to seventh configurations, each of the separation rollers always rotates in a direction opposite to a sheet conveying direction during sheet feeding.

A ninth configuration of the sheet feeding apparatus according to the present invention is as follows.
In any one of the first to eighth configurations, a transport roller attaching member for attaching each transport roller is provided, and the transport roller attaching member is configured to be detachable from the first rotary drive shaft. And

According to a tenth configuration of the sheet feeding apparatus of the present invention, in any one of the first to ninth configurations, there is provided a separation roller mounting member for mounting each separation roller. It is characterized in that it is configured to be detachable from the second rotary drive shaft.

According to the image forming apparatus of the present invention, the first to tenth
And an image forming means for forming an image on a sheet fed by the sheet feeding device.

The image reading apparatus according to the present invention includes first to tenth
And an image reading means for reading an image of the sheet fed by the sheet feeding device.

[0039]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view of a main part of a sheet feeding apparatus to which the present invention is applied, and FIG. 2 is an external view of a main part on a right side for explaining a configuration of each roller in the sheet feeding apparatus and a state during sheet conveyance. FIG. 3 is a schematic configuration diagram for explaining a driving mechanism for driving each roller in the sheet feeding device. FIG. 4 is a cross-sectional view illustrating a configuration of an image forming apparatus including the sheet feeding device. FIG.

(Overall Configuration of Image Forming Apparatus) First, the overall configuration of the image forming apparatus (copier) according to the embodiment will be described with reference to FIG. In FIG. 4, reference numeral 27 denotes an image forming apparatus main body (hereinafter, simply referred to as an apparatus main body), and reference numeral 38 denotes a cassette feeding section as a sheet feeding apparatus.

In the image forming apparatus according to the embodiment, a scanner section 28 as image reading means for reading information on the image surface of a document is provided inside and outside the apparatus main body 27, and below the scanner section 28. An image forming section 17 as an image forming means is disposed, and below the image forming section 17, two upper and lower sheet cassettes 29 (29a, 29a) are provided.
b) and the cassette feeding section 3
A transport unit 39 for transporting the sheet fed from 8 to the image forming unit 17 is provided. In this embodiment, a sorter device 44 is connected to the device main body 27, and each sheet on which an image is formed by the image forming unit 17 is discharged onto a discharge tray 47 of the sorter device 44. ing.

The scanner unit 28 includes a scanning light source unit 30c that emits light for reading an image on a document, a document table glass 31a on which the document is placed, and a document pressure plate 32 that can be opened and closed with respect to the apparatus main body 27. An automatic document feeder 33 and a document discharge tray 34 integrally formed with the document pressure plate 32; a mirror table 30a movably arranged below the document table glass 31a; Conversion element 3
0 and an image processing unit (not shown).

In this image forming apparatus, a book document or a sheet document such as a book, cardboard, or curled paper is placed on the platen glass 31a of the scanner unit 28 with the image side facing down, and pressed by the document pressing plate 32. When the reading start key on the operation panel (not shown) is pressed in the stationary state, the mirror base 30a moves in the direction of the arrow 30b in FIG. The information can be read. The image information of the document read by the photoelectric conversion element 30 by the light from the scanning light source unit 30c is processed by the image processing unit, converted into an electric signal, and transmitted to the laser scanner 35.

In this image forming apparatus, the laser scanner 35 functions as a copying machine when a processing signal of the image processing section is input, and functions as a printer when an output signal of a personal computer is input. Further, by inputting a transmission signal from a facsimile device of another device or transmitting a processing signal of an image processing unit to a facsimile device of another device, the device also functions as a facsimile device.

The scanner section 28 is also capable of automatically feeding a sheet O (hereinafter, referred to as a sheet document) of a document by an automatic document feeding section 33 and reading an image thereof. I have. Here, the automatic document feeder 33
Is a document table 32b capable of stacking a plurality of sheet documents.
A pickup roller 33a for feeding the sheet document O stacked on the document mounting table 32b in contact with the lowermost document, and a conveying roller for separating the sheet document O fed by the pickup roller 33a into one sheet and conveying it. 33b and a separation belt 33c, a driving pulley 33h and a driven pulley 33g for driving the separation belt
It has a transport roller 33d and a transport belt 33e that transport the sheet document O to the document table glass 31a.

In the automatic document feeder 33, the sheet document O stacked on the document table 32b is fed out by the pickup roller 33a, separated and conveyed one by one by the conveyance roller 33b and the separation belt 33c, and further conveyed. By rotating the roller 33d and the transport belt 33e, the sheet document O is transported onto the platen glass 31a. Here, when reading the image of the sheet document O, the mirror table 30a is moved to the document reading position 37 on the document table glass 31a.
Read while standing still under After the image is read, the sheet document O is transferred to the transport belt 33.
e and the conveying roller 33d are rotated and driven in the reverse direction, and are returned onto the document discharge tray 34. In the case of the present embodiment, the document table 32b and the document discharge tray 34 are flush and continuous.

The cassette feeding section 3 below the image forming section 17
Numeral 8 denotes upper and lower 2 which are sheet supporting portions for stacking and supporting sheets.
The sheet feeding cassettes 29a and 29b are provided with a pickup roller 3 as a feeding unit, a conveying roller 2 as a separating and conveying unit, and a separating roller 1 for each of the sheet feeding cassettes 29a and 29b. . Further, on the downstream side of each of the transport rollers 2 and the separation roller 1, a feed roller 11 for feeding a sheet to the image forming unit 17 is disposed.

Each sheet feeding cassette 29a, 29b
It is detachably attached to the device main body 27.
Each of the sheet feeding cassettes 29a and 29b is provided with a middle plate (not shown), on which sheets are stacked and arranged so as to be movable upward in the cassette, and a spring member (not shown) for urging the middle plate upward. The uppermost surface of the sheets stacked on the plate is held at a fixed position.

Pickup roller 3 serving as feeding means
Is movable up and down (in the direction of arrow d in FIG. 1) with respect to each sheet feeding cassette 29 by a solenoid (not shown) or the like. The pick-up roller 3 is driven to rotate in the direction of arrow c in FIG. 1 by a drive motor (not shown) at the time of sheet feeding, and is moved downward by driving of the solenoid or the like to be stacked on the sheet feeding cassette 29. The sheet comes into contact with the uppermost surface of the sheet S, and the sheet is fed to the downstream side.

The transport roller 2 and the separation roller 1 are driven to rotate in the directions of arrows a and b in FIG. 1 by the drive motor, respectively, so that even if the number of sheets picked up by the pickup roller 3 is plural. ,
This is separated into one sheet and is conveyed to the delivery roller 11 side. The details of the transport roller 2 and the separation roller 1 will be described later.

The sheets S stored in the cassettes 29a and 29b are fed out by the pickup roller 3 as described above, and are separated and fed one by one by the transport roller 2 and the separation roller 1, and then guided to the transport section 39. Then, the sheet is fed to the image forming unit 17 by the conveying roller 16 provided in the conveying unit 39 in synchronization with the image forming operation.

The image forming section 17 charges the laser scanner 35, the electrophotographic photosensitive drum 19 irradiated with laser light from the laser scanner 35, and charges the electrophotographic photosensitive drum 19 prior to the irradiation of the laser light. A charging member 19b and a developing device 17 for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive drum 19 into a toner image
a, and a transfer charger 18 for transferring the toner image on the electrophotographic photosensitive drum 19 developed by the developing device 17a onto a sheet.

The image forming section 17 irradiates the surface of the photosensitive drum 19 uniformly charged by the charging member 19b with a laser beam corresponding to image information emitted from the laser scanner 35, thereby forming an electrostatic image. A latent image is formed,
The electrostatic latent image is developed into a toner image by the developing device 17a. Then, in the image forming unit 17, a transfer charger 18 is attached to the first surface of the sheet S transported by the transport roller 16 that rotates in synchronization with the rotation of the photosensitive drum 19.
Transfers the toner image.

At the subsequent stage of the image forming section 17, a conveying belt 41 for conveying the sheet S on which the toner image is formed, a fixing device 42 for fixing the toner image of the sheet S, and a sheet passing through the fixing device 42 A discharge roller 43 for discharging S outside the apparatus main body 27 and the sorter device 44 are arranged. Sheet S on which toner image is formed by image forming unit 17
Is transported to the fixing device 42 by the transport belt 41,
After the toner image is heated and pressed by the fixing device 42 and fixed on the sheet surface, the toner image is carried out to the sorter device 44 by the discharge roller 43.

As shown in FIG. 4, the sorter device 44 has an upper discharge tray 47 and a plurality of discharge bins 48 arranged below the discharge tray 47, and these are integrally formed with a drive motor (not shown). Can be moved back and forth in the vertical direction. The sorter device 44 includes a discharge roller 45 for discharging the sheet discharged from the discharge roller 43 onto a discharge tray 47, and a vertical path portion 46 disposed below the discharge roller 45. . The sheet S carried into the sorter device 44 by the discharge rollers 43 is conveyed by the discharge rollers 45 and discharged to the discharge tray 47.
On the other hand, when the sort discharge is set, the sheet S conveyed into the sorter device 44 by the discharge roller 43 is
Is a vertical path unit 4 by a sheet path switching unit (not shown).
After being sent to 6, they are sequentially discharged to a discharge bin 48.

Next, the details of the cassette feeding section 38 in the image forming apparatus of the embodiment will be described with reference to FIGS. In the following, only the configuration for the upper sheet cassette 29a as the cassette feeding section 38 will be described, and the configuration for the lower sheet cassette 29b is the same as the above, and the description will be omitted.

As shown in FIG. 2, the separation roller 1 and the transport roller 2 of the cassette feeding section 38 are provided with a plurality of roller body sections 1a and 2a which are in contact with the sheet in the respective rotation axis directions, and are not in contact with each other. They face each other alternately in the state. Here, as shown in FIG. 1, the overlap amount between the separation roller 1 and the transport roller 2 is a predetermined amount δ when the sheet is on standby.

More specifically, the separation roller 1 has a plurality of roller bodies 1a and a separation roller collar 1b as a separation roller mounting member, and each roller body 1a is mounted on the separation roller collar 1b at a predetermined interval. Configuration. The separation roller collar 1b is detachably attached to a transport roller shaft 9 as a first rotation drive shaft that is driven to rotate in the sheet feeding direction.

Similarly, the transport roller 2 also has a plurality of roller bodies 2a and a transport roller collar 2b as a transport roller mounting member, and each roller body 2a is mounted on the transport roller collar 2b at a predetermined interval. The transport roller collar 2b is detachably attached to a separation roller shaft 10 serving as a second rotation drive shaft that is driven to rotate in a direction opposite to the sheet feeding direction.

In this embodiment, the transport rollers 2
Shows an example in which the separation roller 1 includes the seven roller body portions 1a, and the separation roller 1 includes the six roller body portions 1a. However, the number of the roller body portions is not limited thereto.

The pickup roller 3 is rotatably supported by a roller holder (not shown) configured to rotate about a transport roller shaft 9 which is a rotation axis of the transport roller 2. The vertical movement in the direction of arrow d in FIG. 1 is repeated every time one sheet is conveyed by an elevating mechanism including a solenoid (not shown) for elevating and lowering the sheet bundle with respect to the uppermost surface of the sheet bundle stacked in the sheet cassette 29a. Contact and separation are repeated. When the sheet is sufficiently conveyed to the downstream side by the conveyance roller 2 and the separation roller 1, the pickup roller 3 is retracted upward by the elevating mechanism so that the sheet is not fed more than necessary.

The rotation direction of each roller is as follows: the pickup roller 3 is the feed direction in the direction of arrow c in FIG. 1, the transport roller 2 is the feed direction in the direction of arrow a in FIG. 1, and the separation roller 1 is the direction of arrow b in FIG. In the return direction.

Next, referring to FIG.
8 will be described. The cassette feeding section 38 is transmitted to the drive input gear 4 to which the driving force of a drive motor (not shown) is transmitted, the transport drive gear 5 and the separation drive gear 6 meshing with the drive input gear 4, and the transport drive gear 5. A drive belt 7 for transmitting a driving force to the pickup roller 3 is provided. Also, the cassette feeding section 38
, The drive input gear 4 is rotatably mounted on the drive input idler shaft 8, and the transport drive gear 5 is connected to the transport roller shaft 9.
, And the separation drive gear 6 is mounted on the separation roller shaft 10. Each of these shafts 8, 9, 10 is rotatably attached to a side plate (not shown) of the treatment main body 27 via a bearing or the like. Further, in the cassette feeding section 38, a pulley (not shown) is attached to the transport roller shaft 9 and the pickup roller shaft 3a of the pickup roller 3, and the drive belt 7 is stretched between the two pulleys.

In the cassette feeding section 38, the rotation driving force of the driving motor is applied to the driving input gear 4 during the sheet feeding driving.
3, the drive input gear 4 rotates in the direction of arrow e in FIG. 3, and the transport drive gear 5 and the separation drive gear 6 meshing with the drive input gear 4 respectively move in the direction of arrow f in FIG.
Then, the transport roller shaft 9 and the transport roller 2 rotate together with the transport drive gear 5, and the separation roller shaft 10 and the separation roller 1 rotate together with the separation drive gear 6. In addition, the rotation of the transport roller shaft 9 rotates the drive belt 7 in the direction of arrow h in the figure, so that the pickup roller 3 rotates in the direction of arrow c in FIG.

As a result, while the sheet is being fed, the transport roller 2 and the pickup roller 3 always rotate forward in the transport direction, and the separation roller 1 always rotates in the reverse direction to the transport direction.

Now, the state of sheet conveyance in the cassette feeding section 38 will be described with reference to the drawings. The sheet S placed on the sheet feeding cassette 29a is fed out by the rotation of the pickup roller 3 (in the direction of arrow c in the figure),
The sheet is sent to a separation / conveyance unit including the conveyance roller 2 and the separation roller 1. In the separation / conveyance section, the conveyance roller 2 is moved by an arrow a in FIG.
1, the separation roller 1 is rotating in the direction of arrow b in FIG. 1. Therefore, when only one sheet is fed by the pickup roller 3, the conveyance force of the conveyance roller 2 having a large friction coefficient Conveyed.

On the other hand, when two or more sheets are fed out from the pickup roller 3, the uppermost sheet is conveyed downstream by the conveying roller 2, and the other sheets rotate in the direction opposite to the conveying direction. The rotation of the separation roller 1 causes the sheet to be returned to the sheet feeding cassette 29a. Then, the sheet carried out from the cassette feeding section 38 is conveyed to the image forming section 17.

As described above, the separation / conveyance section conveys one sheet, conveys only one sheet in the case of a plurality of sheets, and returns the rest to the sheet feeding cassette 29a. Therefore, the relationship between the friction coefficients μ of the rollers 1 and 2 is determined. The friction coefficient μ relationship of these rollers is expressed by the following equation.

Μ _h > μ _r > μ _p (Equation 1) where μ _h is a coefficient of friction between the transport roller 2 and the sheet, and μ _r is a coefficient between the separation roller 1 and the sheet. Coefficient of friction between
μ _p represents the coefficient of friction between the sheets. In this embodiment, μ _h = 2 and μ _r =
By setting it to 1, good and stable separation performance was obtained.

In the cassette feeding section 38, maintenance such as replacement of the rollers 1 and 2 can be easily performed. This configuration will be described below with reference to FIGS.
This will be described with reference to FIG. Here, FIG. 5 is an exploded perspective view showing a state in which the transport roller 2 is detached from the transport roller shaft 9, FIG. 6 is a rear view showing the transport roller 2 from the direction of the arrow in FIG. 5, and FIG. FIG. 8 is an exploded perspective view showing a state where the roller 1 is detached from the separation roller shaft 10, and FIG. 8 is a rear view showing the separation roller 1 from the direction of the arrow in FIG.

First, the configuration of the transport roller 2 will be described in detail with reference to FIGS. Each roller main body 2a of the transport roller 2 is formed of a synthetic rubber material, fitted on a cylindrical transport roller collar 2b, and arranged at substantially equal intervals. In this embodiment, EPDM is used as the synthetic rubber for molding each roller body 2a, but other types of synthetic rubber may be used.

The transport roller collar 2b is connected to the transport roller shaft 9
Is formed, and the insertion hole 2e is formed.
A snap-fit type mounting claw 2c is provided at one end of e so as to be movable in the radial direction. Mounting claw 2c
Is fitted into a groove 9 a provided at the end of the transport roller shaft 9 to fix the transport roller collar 2 b to the transport roller shaft 9.

Insertion hole 2 in transport roller collar 2b
As shown in FIG. 6, a parallel pin groove 2d is provided on the other end of the transfer roller collar 2b. When the transfer roller collar 2b is mounted on the transfer roller shaft 9, the parallel pin groove 2d and the transfer roller shaft 9 When the spring pin 9b fixed to the transfer roller shaft 9 is fitted, the state becomes rotatable in synchronization with the transport roller shaft 9. The parallel pin groove 2d and the spring pin 9b
At the time of fitting, the mounting claw 2c fits into the groove 9a of the transport roller shaft 9, thereby preventing the transport roller collar 2b from coming off the transport roller shaft 9.

During maintenance work such as roller replacement and inspection, the mounting claw 2c is bent upward in FIG. 5 and the mounting claw 2c is disengaged from the groove 9a of the conveying roller shaft 9. 2 is pulled out from the transport roller shaft 9 so that the transport roller shaft 9
The transfer roller 2 can be easily replaced without removing the transfer roller. Therefore, according to the present embodiment, the transport roller 2 can be easily removed from the apparatus main body 27 by a user, and a new one can be easily attached at the time of replacement.

Next, the configuration of the separation roller 1 will be described in detail with reference to FIGS. Each roller body 1a of the separation roller 1 is a sponge roller mainly adhered at equal intervals in the longitudinal direction of the separation roller collar 1b. Specifically, as shown in FIG. The sponge portion 1g thus formed has an outer surface in contact with the sheet as a urethane portion 1h made of urethane. In the present embodiment, the friction coefficient μ of the surface of the separation roller 1 is reduced by forming the outer surface of each roller body 1a of the separation roller 1 with a urethane material.

The separation roller collar 1b is connected to the separation roller shaft 1
0 is formed, and a snap-fit mounting claw 1c is formed at one end of the insertion hole 1e.
Are provided so as to be movable in the radial direction. Mounting claw 1c
Is fitted into a groove 10 a provided at an end of the separation roller shaft 10 to fix the separation roller collar 1 b to the separation roller shaft 10.

Insertion hole 1 in separation roller collar 1b
As shown in FIG. 8, a parallel pin groove 1d is provided on the other end side of the separating roller shaft 1e. By fitting the spring pin 10b fixed to the separation roller shaft 10, it becomes rotatable in synchronization with the separation roller shaft 10. Also, when the parallel pin groove 1d and the spring pin 10b are fitted, the mounting claw 1c is fitted into the groove portion 10a of the separation roller shaft 10, so that the separation roller collar 1b can be removed from the separation roller shaft 10. Is prevented.

In maintenance work such as roller replacement and inspection, the mounting claw 1c is bent upward in FIG.
a and the entire separation roller 2 is separated from the separation roller shaft 1
By pulling out from zero, the separation roller 1 can be easily replaced without removing the separation roller shaft 10 from the apparatus main body 27. Therefore, according to the present embodiment,
Regarding the separation roller 1, even the user can easily use the apparatus main body 27.
And a new one can be easily attached at the time of replacement.

As described above, in the present embodiment, the transport roller collar 1b and the separation roller collar 2b to which the respective roller main bodies 2a and 1a are attached can be attached to and detached from the transport roller shaft 8 and the separation roller shaft 10, respectively. As a result, the maintenance and maintenance of the rollers is significantly improved.

Next, the sheet feeding conditions in the cassette feeding section 38 of the embodiment will be described. In FIG. 1, δ represents the amount of overlap between the separation roller 1 and the transport roller 2, and W represents the overlap area. Further, each separation roller 1 is arranged in a total of n pieces with a width l per piece, and the transport roller 2 is provided with a width L
Are arranged in a total of N pieces. FIG. 9 shows the relationship between these factors affecting the sheet feeding conditions and the sheet feeding conditions.

[0082] Here, the contact area A _r, and the contact area A _h of the conveying roller 2 of the separation roller 1, respectively can be calculated by the following equation.

A _r = l × n × W (Equation 2) A _h = L × N × W (Equation 3) Here, the friction coefficients μ _r and μ _h of each roller inevitably change due to durability. In addition, the balance between the contact areas A _r and A _h of the rollers is important because if one of them is large, the other will be large. In other words, these values are values that cannot be changed greatly, and in many cases, if a certain system is determined, it will be determined naturally.

In this embodiment, as shown in FIG. 2, seven conveying rollers 2 (N = 7) and six separating rollers 1 are used.
(N = 6), but the number of these, that is, the number of N and n is not particularly limited.

Then, for the overlap amount δ,
As described above, in the conventional example of the belt separation method, the belt is bent, and in the present embodiment, the sponge separation roller 1 is deformed, so that the sponge separation roller 1 changes with a change amount corresponding to the rigidity of the sheet to be fed. , Are set to appropriate values.

The amount of change depends on the rigidity of the fed sheet, but it is important to adjust the value of the overlap amount δ in a non-sheet passing state. In the present embodiment, unlike the conventional example of the belt separation method, the dimension of the overlap amount δ can be guaranteed by the outer diameter of the separation roller 1 and the conveyance roller 2, so that the deflection amount of the belt must be considered. The size of δ can be easily obtained as compared with the belt separation method.

In the cassette feeding section 38 of the embodiment in which such a configuration and feeding conditions are set, as shown in a partially enlarged view of FIG. 2, both ends of each of the conveying rollers 2 are chamfered by R. Further, since the separation roller 1 is a sponge-based roller and is deformed so as to be in close contact with the sheet due to the rigidity of the sheet, the sheet can be smoothly deformed into a corrugated shape and the separation performance is stabilized.

Further, since the conveying roller 2 has an R-shaped end having a cross-sectional shape that is not substantially rectangular, the corrugated deformation of the sheet becomes smooth, and the same amount of overlap and the same amount of displacement of the sheet are obtained. , The pitch in the thrust direction of each of the roller body portions 2a, 1a of the transport roller 2 and the separation roller 1 can be reduced, so that the entire transport roller 2 and the entire separation roller 1 can be configured compactly. Roller body portions 2a and 1a can be more easily integrated.

In the present embodiment, the cross-sectional shape of the conveying roller 2 has been described as an example in which the corners at both ends are curved and come into contact with a sheet whose R-chamfered corners. However, the same effect can be obtained by, for example, forming a cross-sectional shape having a plurality of contact surfaces with a sheet having chamfered corners at both end sides. In addition, it goes without saying that the same applies to a configuration that can provide a similar effect that can be easily considered.

As described above, according to the cassette feeding section 38 of the embodiment, the respective roller main bodies 2a of the transport rollers 2 and the respective roller main bodies 1a of the separation roller 1 are overlapped in a non-contact manner. It is easy to maintain the overlap amount at a predetermined amount, and a stable separation ability can be obtained without a large change in the overlap amount during rotation.

The effect of maintaining the transport pressure constant by escaping the belt due to the rigidity of the sheet, which is an advantage of the belt separation system, is described below.
Since a is mainly composed of a spongy material whose shape changes in accordance with the rigidity of the sheet, the present embodiment also has the advantage of keeping the transport pressure constant. In this embodiment, the pulley shaft is set to two as in the belt separation system.
Since there is no need to stretch a belt there, there is no problem of a complicated configuration and high cost, and stable separation performance can be realized with an inexpensive configuration.

Further, in the present embodiment, when the comb-separating mechanism is brought into a characteristic deformed state of the sheet (waveform state as viewed from the advancing direction), each roller main body 2a of the conveying roller 2 is substantially rectangular. As shown in FIG. 2, each roller body 2a of the conveying roller 2 comes into contact with the entire surface of the sheet that has been deformed into a corrugated shape, so that the contact pressure is constant. And the separation roller 1
Since each roller body 1a is a spongy elastic body, the end of each roller body 1a is deformed in accordance with the deformation of the sheet. As a result, a stable separation effect is exhibited, and the range of the adjustment range of the overlap amount can be widened, and a smooth wavy deformation of the sheet is promoted to promote the separation effect, and the feeding performance is stable. It became.

Each roller body 2a of the transport roller 2
Another effect of having a substantially rectangular cross-sectional shape with the corners dropped is that the wave-shaped deformation of the sheet becomes smooth, so that the same amount of overlap and the same amount of displacement of the sheet
The pitch in the thrust direction of the transport roller 2 and the separation roller 1 can be reduced, and each roller body 2
a, 1a can be designed to be compact and each roller body 2
a and 1a are more easily integrated.

According to the embodiment, when the transport roller 2 and the separation roller 1 have reached the end of their life due to a decrease in friction coefficient due to durability wear, they are stretched on two axes like a separation belt. It is only necessary to remove the transport roller collar 2b and the separation roller collar 1b from the transport roller shaft 9 and the separation roller shaft 10, respectively, without using the set belt, so that the removal is easy. There is no need to adjust the overlap amount again, and the transport roller shaft 9 and the separation roller shaft 1 respectively.
The adjustment state before replacement can be easily reproduced simply by attaching to zero.

Therefore, according to the embodiment, it is not necessary to adjust the distance between the pulleys in the belt separation system using the belt pulley and to adjust the position of the transport roller shaft with respect to the positions of these two shafts. Rollers can be easily replaced by general users as well as servicemen,
In addition, there is no longer time consuming adjustment.

Further, even when compared with the conventional configuration in which both the transporting means and the separating means are rollers, when the transporting roller 2 or the separating roller 1 which has reached the end of its life is replaced, each roller body 2a or 1a is transported. They are integrally mounted on the roller shaft 9 or the separation roller shaft 10, respectively. To remove these roller groups, simply remove the separation roller collar 1b or the transport roller collar 2b.
Only the roller group can be easily removed without removing the transport roller shaft 9 or the separation roller shaft 10, and the user can very easily remove the roller group. Further, since the transporting unit and the separating unit are not removed and replaced with each other, a minimum storage space is sufficient when the transporting roller 2 and the separating roller 1 are stored as service parts, and the running cost is also reduced. It became possible.

In the present embodiment, a sponge-based material has been described as an example of the material of the separation roller 1. However, the present invention is not limited to this. Any material can be used as long as it can be deformed by the rigidity of the sheet. Therefore, the material of the separation roller 1 may be, for example, a material based on silicon or urethane.

Further, in the above-described embodiment, an example of the image forming apparatus provided with the sheet feeding device has been described. However, the present invention is not limited to this. It is also possible to use the present invention in an image reading apparatus provided with a reading unit, and a configuration may be adopted in which a stacked sheet document is fed to the image reading unit by a sheet feeding device.

[0099]

As described above, according to the present invention,
A sheet feeding device capable of easily and accurately setting an overlap amount, improving and stabilizing a sheet separating performance, and having a low-cost configuration, which facilitates maintenance work such as a durable life; and It is possible to provide an image forming apparatus or an image reading apparatus including

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a sheet feeding apparatus to which the present invention is applied.

FIG. 2 is an external view of a main part for describing a configuration of each roller in the sheet feeding apparatus and a state during sheet conveyance.

FIG. 3 is a schematic configuration diagram for explaining a driving mechanism for driving each roller in the sheet feeding device.

FIG. 4 is a schematic cross-sectional view illustrating an entire configuration of an image forming apparatus (copier) including the sheet feeding device.

FIG. 5 is an external perspective view illustrating a configuration of a conveyance roller in the sheet feeding apparatus.

FIG. 6 is a main part rear view showing a configuration of the transport roller.

FIG. 7 is an external perspective view illustrating a configuration of a separation roller in the sheet feeding apparatus.

FIG. 8 is a main part rear view showing a configuration of a separation roller in the sheet feeding device.

FIG. 9 is a diagram illustrating a relationship between an overlap amount between a separation roller and a conveyance roller, a friction coefficient of the separation roller and the conveyance roller, and a contact area with a sheet feeding condition.

FIG. 10 is a schematic configuration diagram for explaining a sheet feeding apparatus provided with a conventional belt-separated comb-type separating mechanism.

FIG. 11 is an external view of a main part for describing a configuration of each roller and a state at the time of sheet conveyance in a sheet feeding apparatus provided with a conventional belt separation type comb tooth separation mechanism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Separation roller (separation means) 1a Roller body part 1b Separation roller collar (separation roller attachment member) 1c Attachment claw 1d Parallel pin groove 1g Sponge part 1h Urethane part 2 Transport roller (conveyance means) 2a Roller main body part 2b Transport roller collar ( 2c mounting claw 2d parallel pin groove 2e insertion hole 3 pickup roller 3a pickup roller shaft 4 drive input gear 5 transfer drive gear 6 separation drive gear 7 drive belt 8 drive input idler shaft 9 transfer roller shaft (first) 9a Groove portion 9b Spring pin 10 Separation roller shaft (second rotary drive shaft) 10a Groove portion 10b Spring pin 16 Transport roller 17 Image forming portion 17a Developing device 18 Transfer charger 19 Electrophotographic photosensitive drum 19b Charging member 29 (29a, 29b) Sea Feeding cassette (sheet supporting section) 27 Device main body 28 Scanner section 30 Photoelectric conversion element 30a Mirror table 30c Scanning light source 31a Document table glass 32 Document pressure plate 33 Automatic document feeding section 33a Pickup roller 33b Transport roller 33c Separation belt 33d Transport roller 33e Conveyor belt 33h Drive pulley 33g Follower pulley 34 Document discharge tray 35 Laser scanner 37 Document reading position 38 Cassette feeder (sheet feeder) 39 Transporter 41 Transport belt 42 Fixing device 43 Discharge roller 44 Sorter 45 Discharge roller 46 Vertical path 47 Output tray 48 Output bin

Claims (12)

[Claims] 1. A sheet supporting portion for supporting a stack of sheets,
A feeding unit that feeds out the sheet from the sheet supporting unit; and a separating / conveying unit that separates and conveys the sheet fed from the feeding unit to one sheet, wherein the separating / conveying unit contacts a sheet to be conveyed. In a sheet feeding device comprising a sheet conveying means for feeding the sheet and a sheet separating means for preventing the sheet from being advanced when the sheet comes in contact with a sheet other than the sheet to be conveyed, First driven to rotate
A rotation drive shaft, and a plurality of conveyance rollers attached to the first rotation drive shaft, wherein the sheet separation means is a second rotation drive shaft that is driven to rotate in a direction opposite to a feeding direction; A plurality of separation rollers attached to the second rotation drive shaft, wherein each of the separation rollers faces a portion where each of the conveyance rollers is not arranged, and is not in contact with each of the conveyance rollers. And are arranged to overlap,
The sheet feeding device, which is formed of an elastic body having a lower hardness than each of the transport rollers, and wherein each of the transport rollers is chamfered on both ends. 2. The sheet feeding device according to claim 1, wherein each of the conveying rollers has a cross-sectional shape so as to contact the sheet in a curved line. 3. The sheet feeding device according to claim 1, wherein each of the conveying rollers has a cross-sectional shape having a plurality of contact surfaces with a sheet. 4. The sheet feeding device according to claim 1, wherein each of the transport rollers is made of synthetic rubber. 5. The sheet feeding device according to claim 1, wherein each of the separation rollers is made of at least one of urethane, silicon, and sponge. 6. The sheet feeding device according to claim 1, wherein the surface of each of the separation rollers is formed of a material having a lower coefficient of friction than the surface of the transport roller. . 7. The sheet feeding device according to claim 6, wherein the surface of each of the separation rollers is formed of a urethane material. 8. The sheet feeding apparatus according to claim 1, wherein each of the separation rollers constantly rotates in a direction opposite to a sheet conveying direction during sheet feeding. 9. The apparatus according to claim 1, further comprising a transport roller mounting member for mounting each of said transport rollers, wherein said transport roller mounting member is configured to be detachable from said first rotary drive shaft. 9. The sheet feeding device according to any one of claims 1 to 8. 10. The apparatus according to claim 1, further comprising a separation roller mounting member for mounting each of the separation rollers, wherein the separation roller mounting member is configured to be detachable from the second rotary drive shaft. 10. The sheet feeding device according to any one of claims 9 to 9. 11. A sheet feeding device according to claim 1, further comprising: an image forming unit that forms an image on a sheet fed by the sheet feeding device. Image forming device. 12. An image, comprising: the sheet feeding device according to claim 1; and image reading means for reading an image of a sheet fed by the sheet feeding device. Reader.