JP2002046874A - Paper feeding device and picture image formation device equipped with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding device capable of certainly feeding a sheet regardless of thickness and rigidity of the sheet and a picture image formation device furnished with it. SOLUTION: A first driving transmission part 15 is provided between a drive shaft 3 free to reciprocally rotate and a feeding means 1, and the feeding means 1 is rotated in the sheet delivering direction by transmitting rotation of the drive shaft 3 to the feeding means 1 at the time when the drive shaft 3 is rotated in the opposite direction of the sheet delivering direction by this first driving transmission part 15. Additionally, a second driving transmission part 16 is provided between the drive shaft 3 and a feeding means 34, rotation of the drive shaft 3 is selectively transmitted to the feeding means 1, 34 by the first and second driving transmission parts 15, 16 in accordance with the rotating direction of the drive shaft 3 by rotating the feeding means 34 in the sheet delivering direction by transmitting rotation of the drive shaft 3 to the feeding means 34 at the time when the drive shaft 3 is rotated in the sheet delivering direction by this second driving transmission part 16, and the feeding performance of both a reversing system high in initial paper feeding pressure and a forwarding system constant in paper feeding pressure is given.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder and an image forming apparatus having the same, and more particularly, to driving of a sheet feeding unit for feeding a sheet to an image forming unit.

[0002]

2. Description of the Related Art A conventional image forming apparatus is provided with a sheet feeding device for feeding a sheet to an image forming section. Such a sheet feeding device separates sheets one by one by a separation slope to form an image. There are some that are fed to the department.

FIG. 10 is a view showing a schematic configuration of an image forming apparatus provided with such a conventional sheet feeding apparatus. In FIG. 10, reference numeral 100 denotes an image forming apparatus, and 101 denotes a horizontal sheet stacking surface 101a. A paper feed tray 102 is a separation slope provided at an end of the paper feed tray 101 in the sheet feeding direction. The separation slope 102 is provided to form an angle θ (obtuse angle) with the stacked sheets S. ing.

Reference numeral 103 denotes a paper feed roller integrally holding a gear 103a; 105, a paper feed roller arm which rotatably holds the paper feed roller 103 and is rotatably held with respect to a drive shaft 104; Reference numeral 106 denotes a drive gear fixed to the drive shaft 104, and reference numerals 107 a to 107 d denote idler gears held by the paper feed roller arm 105, for transmitting the drive of the drive gear 106 to the paper feed roller 103.

Reference numeral 108 denotes a conveying roller, and 109 denotes a conveying roller which is urged by an urging means (not shown) and is in contact with the conveying roller 108 at a predetermined pressure. The sheet S sent out by the paper roller 103 is conveyed. 110 is an upper surface conveyance guide for guiding the upper surface of the sheet, and 111 is a lower surface conveyance guide for guiding the lower surface of the sheet. The sheet feeding device 100A is configured by the sheet feeding tray 101, the sheet feeding roller 103, the sheet feeding roller arm 105, and the like.

On the other hand, in FIG. 1, reference numeral 112 denotes a photosensitive drum, 113 denotes a toner cartridge integrally holding the photosensitive drum 112 and image developing means (not shown), and 114 denotes a photosensitive drum surface to expose a latent image on the photosensitive drum. A laser scanner 115 to be formed is a transfer roller for transferring the toner image formed on the photosensitive drum to the sheet S by developing the latent image formed on the photosensitive drum in a toner cartridge. The photosensitive drum 112, the transfer roller 115, and the like form an image forming unit 100B.

A fixing device 116 fixes the toner image transferred by the transfer roller 115 onto the sheet S.
Reference numeral 17 denotes a discharge roller pair A for conveying the sheet S after the toner image is fixed, 118 denotes a discharge roller pair B for discharging the sheet S out of the image forming apparatus, and 119 denotes a discharge tray on which the discharged sheet S is stacked. is there. Reference numeral 120 denotes a rear end regulating member that supports the rear end of the sheet S and that can be adjusted in position.

The image forming apparatus 1 having such a configuration
When an image is formed at 00, a latent image is first formed on the surface of the photosensitive drum 112 by exposure with a laser scanner 114, and then this latent image is developed by image developing means provided in the toner cartridge 113. As a result, a toner image is formed on the surface of the photosensitive drum.

On the other hand, in parallel with this, the drive shaft 104 is rotated by receiving a drive from a drive mechanism (not shown), and this rotation is performed by the idler gear 107 in the paper feed roller arm 105.
The rotation is transmitted to the paper feed roller 103 via a to 107d, whereby the paper feed roller 103 starts rotating.

By the way, as shown in FIG. 11, the sheet feeding roller 103 is a sheet S (hereinafter, referred to as a top sheet) located at the highest position among the sheets S placed on the sheet stacking surface.
1 is pressed against the upper surface of the sheet feeding roller 1 as described above.
When 03 starts rotating, a feeding force Fp due to frictional force acts on the uppermost sheet S1. Further, the upper sheet S1 uppermost at the same time, the frictional force Fs ₁₂ of the next conveying sheet S2, immediately below the subject as a resistance force.

As a result, the uppermost sheet S1 abuts against the separation slope 102 and the reaction force R from the separation slope 102.
1, the leading end portion is bent, and thereafter, the sheet feeding roller 103 is rotated, so that the sheet S
No. 1 advances in a bent state with the tip abutting on the separation slope. The next transport sheet S2
Is not to proceed with the uppermost sheet S1 to be undergoing frictional force Fs ₂₃ from the sheet S3, located immediately below, it will not be double feeding.

Then, in this way, the paper feed roller 103
The uppermost sheet S <b> 1 separated and sent out by the separation slope 102 is conveyed by the rotation of the conveying roller 108 and the conveying roller 109 shown in FIG. 10, and is sent to the nip between the photosensitive drum 112 and the transfer roller 115.

Thereafter, the toner image formed on the photosensitive drum is transferred to the transfer roller 11 on the sheet S1 fed to the nip between the photosensitive drum 112 and the transfer roller 115.
5, the sheet S1 to which the toner image is further transferred is conveyed to the fixing device 116. After the toner image is fixed in the fixing device 116, the sheet S1 is discharged out of the apparatus main body by a pair of paper discharge rollers Al17 and a pair of paper discharge rollers B118.
The sheet is stacked on the sheet discharge tray 119.

[0014]

In such a conventional paper feeder and an image forming apparatus provided with the same, the rotation of the drive shaft 104 is fed via four (even) idler gears 107a to 107d. When transmitted to the roller 103, the rotation direction of the drive shaft 104 and the rotation direction of the paper feed roller 103 become the same.

On the other hand, when the rotation of the drive shaft 104 is transmitted to the paper feed roller 103 via an odd number of idler gears,
The rotation direction of the drive shaft 104 and the rotation direction of the paper feed roller 103 are opposite. Then, the rotation directions of the drive shaft 104 and the paper feed roller 103 are opposite to each other (hereinafter, referred to as a reverse rotation system).
In such a case, the sheet feeding roller arm 105 rotates downward, so that the sheet feeding roller 103 bites into the sheet S during feeding. As a result, the paper feed pressure suddenly increases, and even if the initial pressure is set low, double feed of thin paper is likely to occur.

When the drive shaft 104 and the feed roller 103 are rotated in the same direction (hereinafter referred to as a forward rotation system), the feed roller arm 105 is rotated upward. Since the force is applied in the direction in which the sheet is fed, the sheet feeding roller arm 105 hardly affects the sheet feeding. For this reason, the paper feed pressure during feeding becomes almost constant, but when the paper feed pressure becomes constant in this way, a high initial pressure is applied to feed a thick paper or a sheet having high rigidity. When the initial pressure is reduced to suppress the double feeding of thin paper and low rigidity sheet, poor feeding of thick paper and high rigidity sheet tends to occur. Become.

Accordingly, the present invention has been made in view of such a situation, and a sheet feeder capable of reliably feeding a sheet regardless of the thickness and rigidity of the sheet, and an image forming apparatus provided with the same. It is intended to provide a device.

[0018]

According to the present invention, there is provided a sheet feeding apparatus in which a sheet stored in a sheet storing unit is fed by a feeding unit.
It is provided between the drive shaft and the feeding means, and when the drive shaft rotates in the direction opposite to the sheet feeding direction, transmits the rotation of the driving shaft to rotate the feeding means in the sheet feeding direction. A first drive transmission unit, provided between the drive shaft and the feeding means, for transmitting rotation of the drive shaft when the drive shaft rotates in a sheet feeding direction to feed the sheet to the sheet feeding means; And a second drive transmission unit for rotating the drive shaft selectively in accordance with the rotation direction of the drive shaft by the first and second drive transmission units. It is characterized by having done.

Further, in the invention, it is preferable that the first drive transmitting portion includes: a rotating member that rotates by the rotation of the drive shaft; an even number of transmitting members that transmit the rotation of the rotating member to the feeding means; An arm member rotatably provided on a shaft and rotatably supporting the even number of transmitting members and the feeding means; and an arm member provided between the rotating member and the drive shaft, wherein the drive shaft is configured to feed a sheet. A clutch member for selectively transmitting the rotation of the drive shaft to the rotation member when rotated in a direction opposite to the direction, wherein the second drive transmission unit is configured to rotate by the rotation of the drive shaft; An odd number of transmitting members for transmitting the rotation of the rotating member to the feeding means, and an arm member rotatably provided on the drive shaft and rotatably supporting the odd number of transmitting members and the feeding means. And the rotation And a clutch means provided between the material and the drive shaft, and selectively transmitting the rotation of the drive shaft to the rotating member when the drive shaft rotates in the sheet feeding direction. Is what you do.

Further, according to the present invention, when the drive shaft rotates in the sheet feeding direction, a force is applied to the arm member by the drive shaft in a direction to separate the feeding means from the sheet,
When the drive shaft rotates in the direction opposite to the sheet feeding direction, a force is applied to the arm member in a direction in which the drive unit presses the feeding means against the sheet.

Further, the present invention is characterized in that the first drive transmission section and the second drive transmission section selectively transmit the rotation of the drive shaft to a common feeding means.

Further, the invention is characterized in that the first drive transmission section and the second drive transmission section transmit rotation of the drive shaft to different feeding means.

Further, according to the present invention, the feeding means to which the rotation of the drive shaft is transmitted by the first drive transmission portion is more than the feeding means to which the rotation of the drive shaft is transmitted by the second drive transmission portion. It is characterized by being provided upstream in the sheet feeding direction.

Further, the present invention is characterized in that the rotation direction of the drive shaft is manually switched.

Further, the present invention is characterized in that the drive shaft is rotated in the sheet feeding direction, and then, after a predetermined time has elapsed, rotated in the direction opposite to the sheet feeding direction.

Further, the present invention includes a detecting means for detecting that the sheet is fed from the feeding means, and a switching means for switching a rotation direction of the drive shaft, wherein the switching means controls the driving shaft. If a detection signal is not input from the detection means even after a predetermined time has elapsed after the sheet is rotated in the sheet feeding direction, the drive shaft is rotated in a direction opposite to the sheet feeding direction. It is assumed that.

Further, the present invention is characterized in that a separation slope for separating and feeding the sheets one by one is provided at an end of the sheet storage means in the sheet feeding direction.

According to the present invention, there is provided an image forming apparatus comprising: an image forming unit; and a sheet feeding device for feeding a sheet to the image forming unit by a feeding means, wherein the sheet feeding device is as described above. It is characterized by being.

[0029]

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

FIG. 1 is a top view showing a schematic configuration of a sheet feeding device provided in an image forming apparatus according to a first embodiment of the present invention, and FIG. 2 is a side sectional view thereof.

In FIGS. 1 and 2, reference numeral 18 denotes a sheet feeding tray which is a sheet storing means for stacking the sheets S, and a slope plate 17 forming a separation slope is provided at an end of the sheet feeding tray 18 in the sheet feeding direction. Is provided. Reference numeral 19 denotes an upper surface of a sheet transport path R for transporting the sheet S to an image forming unit (see FIG. 10) disposed above the sheet feeding device, with one end facing the inclined plate 17. Reference numeral 20 denotes a transport roller pair 20 provided in the sheet transport path R.

Further, in FIG.
A paper feed arm shaft, which is a drive shaft provided in parallel with the slope plate 17, is provided above and a paper feed arm shaft 3 that is driven to rotate forward and backward by a drive device (not shown). Reference numerals 1 and 34 denote first and second paper feed rollers as feeding means. Reference numerals 15 and 16 transmit the drive of the paper feed arm shaft 3 to the first and second paper feed rollers 1 and 34, respectively. First and second drive transmission units for rotating the first and second paper feed rollers 1 and 34.

Here, the first drive transmission unit 15 transmits the first drive gear 4, which is a rotating body that is rotated by the rotation of the paper feed arm shaft 3, and the rotation of the first drive gear 4 to the paper feed roller gear 9. Idler gears 5 to 8 as four (even number) transmitting members for transmitting, and a first one-way clutch 3 as a clutch member for transmitting rotation of the paper feed arm shaft 3 to the first drive gear 4
6 is provided.

In this embodiment, the first one-way clutch 36 drives the sheet feeding arm shaft 3 when the sheet feeding arm shaft 3 rotates in a direction opposite to the sheet feeding direction in FIG. 2, that is, counterclockwise. To the first drive gear 4 so that the drive of the paper feed arm shaft 3 is not transmitted to the first drive gear 4 when the paper feed arm shaft 3 rotates in the sheet feeding direction, that is, clockwise. Has become.

Thus, when the paper feed arm shaft 3 rotates counterclockwise, the drive of the paper feed arm shaft 3 is transmitted to the first drive gear 4 by the first one-way clutch 36, and the first drive gear 4 rotates. Further, the rotation of the first drive gear 4 is transmitted to the paper feed roller gear 9 via four idler gears 5 to 8.

Here, the paper feed roller gear 9 is fixed to the end of the paper feed shaft 10 to which the first paper feed roller 1 is fixed, so that the paper feed arm shaft 3 rotates counterclockwise. When the paper feed roller gear 9 rotates with the rotation,
The first paper feed roller 1 rotates in the sheet feeding direction, that is, clockwise. That is, a reverse rotation system is formed.

On the other hand, the second drive transmission section 16 is a second drive gear 1 which is a rotating body which is rotated by the rotation of the feed arm shaft 3.
2 and the rotation of the second drive gear 12
3 is provided with three (odd) idler gears 30 to 32 for transmitting the rotation of the sheet feeding arm 3, and a second one-way clutch 37 as a clutch means for transmitting the rotation of the paper feed arm shaft 3 to the second drive gear 12.

In the present embodiment, the second one-way clutch 37 drives the paper feed arm shaft 3 when the paper feed arm shaft 3 rotates clockwise in FIG.
It acts so as to be transmitted to the drive gear 12, and the feed arm shaft 3
When is rotated counterclockwise, the drive of the paper feed arm shaft 3 is not transmitted to the second drive gear 12.

As a result, when the paper feed arm shaft 3 rotates clockwise, the drive of the paper feed arm shaft 3 is transmitted to the second drive gear 12 by the second one-way clutch 37, and the second drive gear 12 rotates. Further, the rotation of the second drive gear 12 is transmitted to a sheet feed roller gear 33 via three idler gears 30 to 32.

Here, the feed roller gear 33 is fixed to an end of a feed shaft 35 to which the second feed roller 34 is fixed, whereby the feed arm shaft 3 rotates clockwise. When the paper feed roller gear 33 rotates, the second paper feed roller 34 rotates clockwise. That is, a forward rotation system is formed.

In the figure, 28a and 28b are:
A pair of arm members rotatably provided on the sheet supply arm shaft 3 and rotatably supporting the first sheet supply roller 1.
Four idler gears 5 to 8 are rotatably held on one 28a of 28b.

Reference numerals 29a and 29b denote a sheet feeding arm shaft 3
And a roller arm that is a pair of arm members that rotatably supports the second paper feed roller 34, and one of the pair of roller arms 29a and 29b has three idler gears 30. To 32 are rotatably held.

Next, the sheet feeding operation of the sheet feeding device thus configured will be described.

For example, when the paper feed arm shaft 3 is driven by a driving device (not shown) so as to rotate counterclockwise in FIG. 2, the second one-way clutch 37 idles with the paper feed arm shaft 3. Therefore, the drive transmission from the second drive gear 12 to the paper feed roller 34 is not performed.

On the other hand, the first one-way clutch 36
The first drive gear 4 rotates counterclockwise by the action of the first one-way clutch 36 because the first drive gear 4
Rotates the four idler gears 5 to 8 and the feed roller gear 9.

As a result, the first paper feed roller 1 rotates clockwise in FIG. When the counterclockwise rotation of the first drive gear 4 is transmitted to the idler gear 5 meshing with the first drive gear 4, the roller arms 28a and 28b exert a counterclockwise force, that is, the first sheet feeding roller 1 Is applied in a direction away from the sheet S.

As described above, when the sheet feeding arm shaft 3 rotates in the counterclockwise direction in FIG.
Since there are an even number of sheets, the first sheet feeding roller 1 has a reversing system performance in which the first sheet feeding roller 1 easily bites into the sheet S as the feeding performance.

On the other hand, when driven by a driving device (not shown) so that the feed arm shaft 3 rotates clockwise in FIG. 2, the first one-way clutch 36
Therefore, the drive transmission from the drive gear 4 to the paper feed roller 1 is not performed.

On the other hand, the second one-way clutch 37
The second drive gear 12 rotates clockwise by the action of the second one-way clutch 37 because the tightening action acts on the sheet feed arm 3, and the three idler gears 30 to 32 are rotated by the rotation of the second drive gear 12. And the paper feed roller gear 33 rotates.

As a result, the second paper feed roller 34 rotates clockwise in FIG. When the clockwise rotation of the second drive gear 12 is transmitted to the idler gear 30 meshing with the second drive gear 12, the roller arms 29a, 29b
Is a clockwise force, that is, the second paper feed roller 34 is
The force comes to be applied in the direction of pressing against.

As described above, when the paper feed arm shaft 3 is rotated in the clockwise direction, there are three idler gears, that is, an odd number, so that the second paper feed roller 34 does not easily bite into the sheet S in terms of feeding performance. It will have the performance of a forward rotation system.

Therefore, when thin paper or a sheet having low rigidity is passed, the paper feed arm shaft 3 is rotated clockwise by a drive from a drive unit (not shown) to rotate the paper feed arm shaft 3 from the second drive gear 12 to the second paper feed roller. If the forward rotation drive is transmitted to the sheet S, the second sheet feed roller 34 can be prevented from biting into the sheet S, and the feeding can be suppressed while the double feeding is suppressed.

When passing thick paper or a sheet having high rigidity, the feed arm shaft 3 is rotated counterclockwise to rotate the first arm.
If the drive transmission of the reverse rotation system is performed from the driving gear 4 to the first sheet feeding roller 1, a high sheet feeding pressure can be obtained by making the first sheet feeding roller 1 bite into the sheet S, so that stable feeding can be performed. Will be possible.

As described above, when feeding a thick paper or a sheet having a large rigidity, a high initial sheet feeding pressure of a reverse rotation system is used, and when feeding a thin paper or a sheet having a small rigidity, a forward rotation system having a constant sheet feeding pressure is used. By using a constant feed pressure in the forward rotation system and a high initial feed pressure in the reverse rotation system, it is possible to ensure a wide range of paper types from thin to thick paper regardless of the sheet thickness. The sheet can be fed at the same time.

As a drive switching method between the forward rotation system and the reverse rotation system, there is a method in which the user manually switches between the forward rotation system and the reverse rotation system. For example, by manually operating a driving device (not shown) to switch the rotation direction of the paper feed arm shaft 3, the first paper feed roller 1 that easily penetrates the sheet S is used for thick paper, and the thin paper is used for the thin paper. By using the second paper feed roller 34 that hardly penetrates the sheet S, the sheet can be reliably fed. As described above, by using the paper feed rollers 1 and 34 corresponding to the paper type, it is possible to prevent troubles such as thin paper double feed and thick paper feed failure.

As a drive switching method between the forward rotation system and the reverse rotation system, first, the sheet is fed by the forward rotation system with the rotation direction of the sheet feeding arm shaft 3 clockwise, and thereafter, when a predetermined time elapses. Alternatively, the forward rotation system and the reverse rotation system may be sequentially switched such that the sheet is fed by the reverse rotation system with the rotation direction of the paper feed arm shaft 3 being counterclockwise.
In other words, after the transmission of the drive to the second paper feed roller 34 is started, the drive may be controlled to be transmitted to the first paper feed roller 1 with an interval.

Then, with this configuration,
At the time of thin paper feeding, sheets can be fed while preventing double feeding by the second paper feeding roller 34. At the time of thick paper feeding, even if the feeding by the second paper feeding roller 34 fails, a predetermined time elapses. Thereafter, the first paper feed roller 1 is driven, so that thick paper can be reliably fed. Thus, it is possible to feed various paper types having different rigidities from thin paper to thick paper.

Further, as a drive switching method between the forward rotation system and the reverse rotation system, first, the rotation direction of the sheet feeding arm shaft 3 is clockwise to drive the forward rotation system, and the sheet is not fed by the forward rotation system. Alternatively, the driving direction may be switched to the reverse rotation system with the rotation direction of the paper feed arm shaft 3 being set counterclockwise. In other words, the second paper feed roller 34 having a stable paper feed pressure is used as the main feeding means, and the drive is switched to the first paper feed roller 1 only when the second paper feed roller 34 cannot feed. To be able to feed.

More specifically, a detecting means (not shown) for detecting the sheet S sent to the sheet conveying path R is provided, and the detecting means detects the sheet fed by the second sheet feeding roller 34 for a predetermined time. If the detection is not possible even if the detection signal is not input even after a predetermined time has elapsed since the feeding of the sheet by the second paper feed roller 34 is started, the switching means (not shown) The rotation direction of the shaft 3 is switched counterclockwise so that the first sheet feed roller 1 feeds the sheet.

With the above-described configuration,
Usually, the use of the second paper feed roller 34 having a stable paper feed pressure makes double feed and jam less likely to occur, and the first paper feed roller 34 is used for thick paper, etc., which is difficult to feed with the second paper feed roller 34. Since the drive transmission is switched to 1, the optimal feeding means for the paper type can be automatically selected. Thus, the sheet can be reliably fed from thin paper to thick paper regardless of the thickness of the sheet.

Heretofore, the first and second drive transmitting portions 15 and 16 have respectively controlled the driving of the paper feed arm shaft 3 to the first position.
And the case of transmitting to the second paper feed rollers 1 and 34 has been described. However, the present invention is not limited to this, and a common paper feed roller is used, and the common paper feed roller is connected to the first and second paper feed rollers.
The drive transmission units 15 and 16 may be configured to selectively rotate.

FIG. 3 is a top view showing a schematic configuration of a sheet feeding device provided in such an image forming apparatus according to the second embodiment of the present invention, and FIG. 4 is a side view thereof. Note that, in the figure, the same reference numerals as those in FIGS. 1 and 2 indicate the same or corresponding parts.

In FIGS. 3 and 4, 1A is a common paper feed roller, and 10A is a roller shaft fixing the paper feed roller 1A. Feed roller gears 9, 33 are fixed to both ends of the roller shaft 10A. Also,
Reference numerals 21 and 22 denote a pair of roller arms rotatably provided on the sheet feeding arm shaft 3 and rotatably supporting the sheet feeding roller 1A. One roller arm 21 of the pair of roller arms 21 and 22 has , 4 idler gears 5-8
Are rotatably held. Further, three idler gears 30 to 32 are rotatably held on the other roller arm 22.

Next, the paper feeding operation of the paper feeding device thus configured will be described.

For example, when the paper feeding arm shaft 3 is driven by a driving device (not shown) so as to rotate counterclockwise in FIG. 4, the second one-way clutch 37 idles with the paper feeding arm shaft 3. Therefore, the drive transmission from the second drive gear 12 to the paper feed roller 1A is not performed.

On the other hand, the first one-way clutch 36
Is driven by the first drive gear 4 through the four idler gears 5 to 8 and the paper feed roller gear 9 so that the drive is transmitted to the paper feed roller 1A. The paper feed roller 1A rotates clockwise.

As described above, when the paper feed arm shaft 3 rotates in the counterclockwise direction, there are four idler gears, that is, an even number of idler gears. It will have easy reverse system performance.

When the paper feed roller 1A rotates in this way, the rotation of the paper feed roller 1A is
And three idler gears 3 via a paper feed roller gear 33.
However, the second one-way clutch 37 does not act on the paper feed arm shaft 3 and does not affect the rotation of the paper feed arm shaft 3 at this time. .

On the other hand, when the drive arm (not shown) is driven to rotate the paper feed arm shaft 3 clockwise, the first
Since the one-way clutch 36 idles with the paper feed arm shaft 3, the drive transmission from the drive gear 4 to the paper feed roller 1 is not performed.

On the other hand, the second one-way clutch 37
The second one-way clutch 37 allows the second driving gear 12 to drive the paper feed roller 1A through the three idler gears 30 to 32 and the paper feed roller gear 33 because the second one-way clutch 37 operates. Thus, the paper feed roller 1A rotates clockwise.

As described above, when the paper feed arm shaft 3 is rotated in the clockwise direction, there are three idler gears, that is, an odd number, so that the second paper feed roller 34 is unlikely to bite into the sheet S in terms of feeding performance. It will have the performance of a forward rotation system.

Therefore, when thin paper is passed, the paper feed arm shaft 3 is rotated clockwise to transmit the forward rotation drive from the drive gear 12 to the paper feed roller 1A. The feed becomes smaller and double feed is suppressed. When the thick paper is passed, the paper feed arm shaft 3 is rotated counterclockwise and the drive gear 4 transmits a reverse rotation drive to the paper feed roller 1A, so that a high paper feed pressure can be obtained. Therefore, the cardboard can be fed stably.

As described above, the rotation of the feed arm shaft 3 is
And selectively transmitted to the common paper feed roller 1A by the second drive transmission portions 15 and 16, that is, when the paper feed arm shaft 3 is rotated counterclockwise, the first drive transmission portion 15 feeds paper. When the rotation of the arm shaft 3 is transmitted and the paper feed arm shaft 3 is rotated in the clockwise direction, the rotation of the paper feed arm shaft 3 is transmitted by the second drive transmission unit 16 so that the common paper feed roller Even when 1A is used, both forward and reverse performance can be provided. This makes it possible to provide an inexpensive paper feeder that can handle a wide variety of paper types from thin paper to thick paper and has a reduced number of components.

FIG. 5 shows the first and second drive transmission units 1.
FIG. 6 is a top view showing a schematic configuration of a sheet feeding device provided in an image forming apparatus according to a third embodiment of the present invention, in which a common sheet feeding roller is selectively rotated by 5 and 16;
Is a side view thereof. In the figure, the same reference numerals as those in FIGS. 3 and 4 indicate the same or corresponding parts.

In FIGS. 5 and 6, reference numeral 25 denotes a paper feed shaft to which the paper feed roller gear 9 is fixed, and reference numeral 23 denotes a first one-way clutch. Here, in the present embodiment, the first one-way clutch 23 is provided between the paper feed arm shaft 3 and the first drive gear 4 as in the first and second embodiments described above. Not the roller shaft 1 of the paper feed roller 1A
0A and the paper feed shaft 25 of the paper feed roller gear 9, so that the tightening action only works when the paper feed shaft 25 rotates clockwise in FIG.

Reference numeral 27 denotes a paper feed shaft to which the paper feed roller gear 33 is fixed, and reference numeral 24 denotes a second one-way clutch. Here, in the present embodiment, the second one-way clutch 24 is provided between the paper feed arm shaft 3 and the second drive gear 12 as in the first and second embodiments described above. Instead, it is provided between the roller shaft 10A of the paper feed roller 1A and the paper feed shaft 27 of the paper feed roller gear 33,
Only when the paper feed shaft 27 rotates clockwise in FIG. 6, the tightening action works.

On the other hand, FIG. 7 shows the roller shaft 10A of the paper feed roller 1A, the paper feed shaft 25 of the paper feed roller gear 9, the paper feed shaft 27 of the paper feed roller gear 33, the first and second one-way clutches 23, 24 is a diagram showing a relationship between the sheet feeding shaft 25 of the sheet feeding roller gear 9 and the roller shaft 10A as shown in FIG.
Feed shaft 27 of feed roller gear 16 and roller shaft 10A
And a small gap exists between them. The feed shafts 25, 27 and the roller shaft 10A are connected by first and second one-way clutches 23, 24.

Next, the paper feeding operation of the paper feeding device configured as described above will be described.

For example, when the sheet feeding arm shaft 3 is driven by a driving device (not shown) so as to rotate counterclockwise in FIG. 6, the driving gears 4 and 12 move together with the sheet feeding arm shaft 3 counterclockwise. The rotation and the drive are transmitted to each idler gear.

That is, the drive transmitted from the drive gear 4 rotates the sheet feed roller gear 9 clockwise through four idler gears 5 to 8, and the drive transmitted from the drive gear 12 passes through three idler gears 30 to 32. The sheet feed roller gear 33 is rotated counterclockwise.

Here, when the paper feed roller gear 9 rotates clockwise, the paper feed shaft 25 rotates clockwise. Thus, when the paper feed shaft 25 rotates clockwise, the tightening operation of the first one-way clutch 23 is performed. As a result, the clockwise rotation of the paper feed shaft 25 is transmitted to the roller shaft 10A via the first one-way clutch 23, and as a result, the paper feed roller 1A rotates. Although the paper feed shaft 27 of the paper feed roller gear 33 rotates counterclockwise, the second one-way clutch 24 does not act in this rotation direction, so that the drive transmission from the paper feed shaft 27 to the roller shaft 10A is not performed. I can't.

Therefore, the feed roller 1A rotates clockwise because the drive is transmitted only from the feed roller gear 9 side.
The driving characteristics at this time are as follows.
This is the drive of the reversing system that is easy to bite into

On the other hand, when the sheet feeding arm shaft 3 is driven by a driving device (not shown) so as to rotate clockwise, the driving is transmitted in the same flow as described above, and the sheet feeding roller gear 9 rotates counterclockwise. The paper feed roller gear 33 rotates clockwise.

Here, when the paper feed roller gear 33 rotates clockwise, the paper feed shaft 27 rotates clockwise, and when the paper feed shaft 27 rotates clockwise, the tightening action of the second one-way clutch 24 is performed. As a result, the clockwise rotation of the paper feed shaft 27 is transmitted to the roller shaft 10A via the second one-way clutch 24, and as a result, the paper feed roller 1A rotates. Note that the feed shaft 25 of the feed roller gear 9 rotates counterclockwise, but the first one-way clutch 23 does not act in this rotation direction, so that the drive transmission from the feed shaft 23 to the roller shaft 10A is not performed. I can't.

Therefore, since the drive is transmitted to the paper feed roller 1A only from the paper feed roller gear 33 side, the paper feed roller 1A rotates clockwise. The driving characteristic at this time is that of a forward rotation system in which the sheet feeding roller 1A hardly bites into the sheet S.

[0086] Then, with this configuration,
By controlling the paper feed arm shaft 3 to rotate clockwise during thin paper feeding, feeding is performed in a forward rotation system, and a feeding operation in which double feeding is unlikely to occur can be obtained. Further, at the time of thick paper feeding, by controlling the paper feeding arm shaft 3 to rotate counterclockwise, feeding is performed in a reverse rotation system, and a stable feeding operation can be obtained under a high feeding pressure.

Next, a fourth embodiment of the present invention will be described.

FIG. 8 is a top view showing a schematic configuration of a sheet feeding device provided in the image forming apparatus according to the present embodiment, and FIG. 9 is a side view thereof. 8 and 9, the same reference numerals as those in FIGS. 1 and 2 denote the same or corresponding parts.

In FIGS. 8 and 9, reference numeral 26 denotes a second drive transmission unit for transmitting the drive of the feed arm shaft 3 to the second feed roller 34 to rotate the second feed roller 34. Here, the second drive transmission unit 26 includes a second drive gear 12 that rotates by rotation of the paper feed arm shaft 3, and five (odd) that transmit the rotation of the second drive gear 12 to the paper feed roller gear 33. , And a second one-way clutch 37 for transmitting the rotation of the paper feed arm shaft 3 to the second drive gear 12.

In the present embodiment, when the paper feed arm shaft 3 rotates clockwise in FIG. 9, the second one-way clutch 37 drives the paper feed arm shaft 3 to the second position.
It acts so as to be transmitted to the drive gear 12, and the feed arm shaft 3
When is rotated counterclockwise, the drive of the paper feed arm shaft 3 is not transmitted to the second drive gear 12.

Thus, when the paper feed arm shaft 3 rotates clockwise, the driving of the paper feed arm shaft 3 is transmitted to the second drive gear 12 by the second one-way clutch 37, and the second drive gear 12 rotates. Further, the rotation of the second drive gear 12 is transmitted to the feed roller gear 33 via the five idler gears 38 to 41 and 42, and the feed roller gear 33 rotates. When the feed roller gear 33 rotates in this manner, the second feed roller 34 rotates clockwise. That is, a forward rotation system is formed.

The first drive transmission section 15 has a configuration similar to that of, for example, the first embodiment described above. Therefore, when the paper feed arm shaft 3 rotates counterclockwise in FIG. 9, the drive of the paper feed arm shaft 3 is transmitted to the first drive gear 4 by the first one-way clutch 36, and the first drive gear 4 rotates. Further, the first drive gear 4
Is transmitted to the paper feed roller gear 9 via the four idler gears 5 to 8, whereby the first paper feed roller 1 rotates clockwise. That is, a reverse rotation system is formed.

[0093] With this configuration,
When the paper feed arm shaft 3 rotates clockwise in FIG.
Only the one-way clutch 36 acts to rotate the sheet feeding roller gear 9 clockwise in FIG. 9 from the driving gear 4 via the five idler gears, so that the sheet feeding roller 1 also receives clockwise driving at the same time. The characteristic is a forward rotation system.

When the paper feed arm shaft 3 rotates counterclockwise in FIG. 9, only the one-way clutch 37 operates, so that the paper feed roller gear 33 and the paper feed roller 34 are driven from the drive gear 12 via four idler gears. In FIG. 9, driving is started in a clockwise direction, and the driving characteristics are reverse.

By the way, in the present embodiment, the first
A roller arm 29 (29a, 29b) that rotatably holds the paper feed roller 34 of the second drive transmission unit 26, rather than a roller arm 28 (28a, 28b) that rotatably holds the paper feed roller 1 of the drive transmission unit 15. ) Is longer.

By extending the roller arm 29 of the second drive transmission section 26 in this manner, a forward rotation system can be arranged at a position close to the inclined plate 17 and a reverse rotation system can be arranged at a position far from the inclined plate 17. . By feeding the leading end of the sheet S by driving the forward rotation system, a great effect is prevented in the double feeding of thin paper, and the sheet S is bent at the time of feeding by moving the reverse rotation system away from the inclined plate 17. Since the sheet S can be easily fed, the sheet S can be fed without applying a great deal of stress to the sheet S even when feeding thick paper, and defective feeding can be prevented.

In the second to fourth embodiments, the drive switching system for the forward rotation system and the reverse rotation system can be the same as that in the first embodiment described above.

[0098]

As described above, according to the present invention, the first and second drive transmission portions provided between the drive shaft capable of rotating in the normal and reverse directions and the feeding means select according to the rotation direction of the drive shaft. By transmitting the rotation of the drive shaft to the feeding means, it is possible to provide the feeding performance of both a system having a high initial paper feeding pressure and a system having a constant paper feeding pressure. The sheet can be fed reliably according to the condition.

[Brief description of the drawings]

FIG. 1 is a top view illustrating a schematic configuration of a sheet feeding device provided in an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of the paper feeding device.

FIG. 3 is a top view illustrating a schematic configuration of a sheet feeding device provided in an image forming apparatus according to a second embodiment of the present invention.

FIG. 4 is a side sectional view of the paper feeding device.

FIG. 5 is a top view illustrating a schematic configuration of a sheet feeding device provided in an image forming apparatus according to a third embodiment of the present invention.

FIG. 6 is a side sectional view of the paper feeding device.

FIG. 7 is an enlarged perspective view around a sheet feeding roller of the sheet feeding device.

FIG. 8 is a top view illustrating a schematic configuration of a sheet feeding device provided in an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 9 is a side cross-sectional view of the paper feeding device.

FIG. 10 is a diagram illustrating a schematic configuration of an image forming apparatus including a conventional sheet feeding device.

FIG. 11 is a diagram illustrating a sheet separating operation of the conventional sheet feeding device.

[Explanation of symbols]

 1, 34 (first and second) paper feed rollers 3 paper feed arm shafts 4, 12 (first and second) drive gears 5 to 8 idler gears 9, 33 paper feed roller gears 15 first drive transmission unit 16, 26th 2 Drive transmission unit 17 Slope plate 18 Paper feed tray 21, 21, 28, 29 Roller arm 23, 36 First one-way clutch 24, 37 Second one-way clutch 30 to 32 Idler gear 38 to 41, 42 Idler gear S Sheet

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takayoshi Inoue 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 3F343 FA02 FB01 FC01 GA01 GB01 GC01 GD01 JA04 JA19 JD08 KB04 KB12 KB17 KB19 LA04 LA15 LC07 LC15 LC22 LC25 LD24 MC21

Claims (11)

[Claims] 1. A sheet feeding device configured to feed a sheet stored in a sheet storage unit by a feeding unit, wherein the driving shaft is provided between the driving shaft and the feeding unit, the driving shaft being rotatable forward and backward, A first drive transmission unit that transmits rotation of the drive shaft when the drive shaft rotates in a direction opposite to the sheet feeding direction to rotate the feeding unit in the sheet feeding direction; and the drive shaft and the feeding unit. A second drive transmission unit that is provided between the first and second transmission units and transmits the rotation of the drive shaft when the drive shaft rotates in the sheet feeding direction to rotate the feeding unit in the sheet feeding direction. A sheet feeder, wherein the rotation of the drive shaft is selectively transmitted to the feeding means by the first and second drive transmission units according to the rotation direction of the drive shaft. 2. The power transmission device according to claim 1, wherein the first drive transmission unit includes: a rotation member that rotates by rotation of the drive shaft; an even number of transmission members that transmit rotation of the rotation member to the feeding unit; An arm member movably provided and rotatably supporting the even number of transmission members and the feeding means; and an arm member provided between the rotation member and the drive shaft, wherein the drive shaft is opposite to a sheet feeding direction. Clutch means for selectively transmitting the rotation of the drive shaft to the rotation member when rotated in the direction, the second drive transmission unit includes a rotation member that rotates by rotation of the drive shaft, and a rotation member. An odd number of transmission members for transmitting the rotation of the transmission member to the feeding means; an arm member rotatably provided on the drive shaft and rotatably supporting the odd number of transmission members and the feeding means; Rotating member and the drive And a clutch provided between the shaft and the shaft to selectively transmit the rotation of the drive shaft to the rotating member when the drive shaft rotates in the sheet feeding direction. Paper feeder as described. 3. When the drive shaft rotates in a sheet feeding direction, a force is applied to the arm member by the drive shaft in a direction separating the sheet feeding means from the sheet, and the driving shaft is moved in a direction opposite to the sheet feeding direction. 3. The sheet feeding device according to claim 2, wherein when the arm member is rotated, a force is applied to the arm member by the drive shaft in a direction of pressing the sheet feeding unit against the sheet. 4. The apparatus according to claim 1, wherein the first drive transmission unit and the second drive transmission unit selectively transmit rotation of the drive shaft to a common feeding unit. 1
Paper feeder according to the item. 5. The apparatus according to claim 1, wherein the first drive transmission unit and the second drive transmission unit transmit rotation of the drive shaft to different feeding units. Paper feeder. 6. A sheet feeding direction in which the rotation of the drive shaft is transmitted by the first drive transmission unit, and a sheet feeding direction in which the rotation of the drive shaft is transmitted by the second drive transmission unit. The sheet feeding device according to claim 5, wherein the sheet feeding device is provided upstream. 7. The sheet feeding device according to claim 1, wherein a rotation direction of the drive shaft is manually switched. 8. The apparatus according to claim 1, wherein the drive shaft is rotated in the sheet feeding direction, and is rotated in a direction opposite to the sheet feeding direction after a predetermined time has elapsed. Paper feeder according to the item. 9. A detecting means for detecting that the sheet is fed from the feeding means, and a switching means for switching a rotation direction of the drive shaft, wherein the switching means feeds the drive shaft to the sheet. If the detection signal is not input from the detection means even after a predetermined time has elapsed after the rotation in the direction, the drive shaft is rotated in a direction opposite to the sheet feeding direction. Item 7. The sheet feeding device according to any one of Items 1 to 6. 10. The sheet storage device according to claim 1, wherein a separation slope for separating and feeding the sheets one by one is provided at an end of the sheet storage unit in a sheet feeding direction. Paper feeder. 11. An image forming apparatus comprising: an image forming unit; and a sheet feeding device that feeds a sheet to the image forming unit by a feeding unit, wherein the sheet feeding device is any one of claims 1 to 10. An image forming apparatus characterized in that: