JP2003146455A - Sheet feeder and image forming device equipped with the feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent double feeding of thin sheets and to resurely feed thick sheets in a separation slope system. SOLUTION: A sheet feeder 100 comprises a sheet feed tray 22 for receiving sheets P, and a separation slope 21 arranged downstream in a sheet feeding direction in the tray 22 and separating the fed sheets one by one. For the separation slope 21, two feed rollers 1, 11 are arranged upstream and downstream in the sheet feeding direction at distances therefrom, respectively, and by these rollers 1, 11, the sheets P contained in the tray 22 are transported in the sheet feeding direction. The feed rollers 1 between those 1, 11, which are closer to the separation slope 21, perform feeding of the sheets P one by one while preventing double feeding, and the rollers 11 serve to assist the transport of the sheets P loosened by the roller 1.

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 that separates and feeds sheets one by one, and an image forming apparatus including the sheet feeding apparatus.

[0002]

2. Description of the Related Art FIG. 9 shows a slope separation type sheet feeding apparatus in a conventional image forming apparatus. In the figure, a separation slope 102 is disposed on the tip contact surface in the sheet feeding direction of the sheet storage means 101 having a sheet stacking surface, and the separation slope 102 is θ with respect to the stacked sheets.
Are formed so as to form an angle of. Above the stacked sheet bundle S, a feeding roller 10 integrally holding gears is provided.
3 is arranged, and the feeding roller 103 is rotatably held by a support arm 105. The support arm 105 is held rotatably up and down about a drive shaft 104, and a drive gear 106 is fixed to the drive shaft 104. The drive gear 106 is driven by the idler gear 10 held by the support arm 105.
It is transmitted to the feeding roller 103 via 7a to 107d.

FIG. 10 is an enlarged view of the contact portion of the feeding roller 103, and is a diagram for explaining the action of force during the feeding operation.

With the above structure, sheet feeding and image formation are performed as follows.

The above-mentioned drive shaft 104 is driven by a controllable drive mechanism (not shown), which controls the start and stop of the feeding operation. When the feeding is started, the drive shaft 104 is driven by a drive mechanism (not shown) to rotate. The rotation of the drive shaft 104 is transmitted to the feeding roller 103 via the idler gears 107a to 107d in the support arm 105, and the feeding roller 103 starts rotating.

The feeding roller 103 is located on the uppermost surface of the sheet bundle S placed on the sheet stacking surface.
Since the upper surface of the sheet S1 is pressed against the upper surface of the sheet S1, the sheet feeding roller 103 starts to rotate, and thus the sheet feeding force Fp due to the frictional force acts on the uppermost sheet S1. At the same time, the sheet S1
Receives the frictional force Fs12 with the sheet S2 immediately thereunder as a resistance force. Here, the sheet S1 is the separation slope 1
02 receives the reaction force R1, but the reaction force causes the sheet S
1 is bent, and the sheet S1 advances on the separation slope 102 in a bent state with its tip abutting. The sheet S2 does not proceed by receiving the frictional force Fs23 from the sheet S3 immediately below the sheet S2, and thus, the double feed does not normally occur.

[0007]

However, in the above-mentioned conventional example, when the feeding roller 103 is arranged near the separation slope 102, the sheet after feeding is less likely to bend on the slope, which makes it difficult to double feed thin sheets. Is effective but not suitable for feeding thick sheets. Further, when the feeding roller 103 is arranged far from the separation slope 102, a thick sheet is easily fed because the sheet after feeding is easily bent on the slope.
On the other hand, double feeding of thin sheets is also likely to occur.

As described above, since various problems occur depending on the positional relationship between the feeding roller 103 and the separation slope 102, it is difficult to determine the optimum position of the feeding roller 103.

The present invention has been made to solve the above problems, and an object thereof is to prevent double feed of thin sheets and to reliably feed thick sheets. An object is to provide a feeding device and an image forming apparatus including the same.

[0010]

In order to achieve the above-mentioned object, the invention according to claim 1 is a sheet accommodating means for accommodating a sheet and a sheet accommodating means arranged downstream of the sheet accommodating means in the sheet feeding direction and fed out. In the sheet feeding device having a separation slope for separating the sheets to be separated one by one, the sheets stored in the sheet storage means are arranged separately from each other on the upstream side in the sheet feeding direction with respect to the separation slope. It is characterized in that it is provided with a first feeding means and a second feeding means for feeding in the feeding direction.

According to a second aspect of the present invention, the first feeding means and the second feeding means are connected to a drive shaft via a power transmission mechanism, and one end of the drive shaft is rotatable. It is characterized in that it is supported on the other end side of a support member that is axially attached.

According to a third aspect of the present invention, there is provided selection means for selecting at least one of the first feeding means and the second feeding means, and the feeding means on the selected side is powered. It is characterized in that it can be transmitted.

According to a fourth aspect of the present invention, there is provided delay means for transmitting power to the second feeding means after a lapse of a predetermined time from the start of power transmission to the first feeding means. Is characterized by.

According to a fifth aspect of the present invention, the power transmission path of the power transmission mechanism is branched midway, and the first feeding means or the second feeding means is provided at each end side of the branched power transmission path. It is characterized in that a feeding means is provided.

According to a sixth aspect of the invention, the sheet feeding device according to any one of the first to fifth aspects, and an image forming section for forming an image on a sheet fed from the sheet feeding device. And are provided.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sheet feeding device of the slope separation type and an image forming apparatus having the same. In the figure, the sheet feeding device 100 (100A to 100D) is
Paper feed tray (sheet storage means) 22 having a sheet stacking surface
And a pair of feed rollers 1 and 11 described later that feeds sheets P such as recording paper from the paper feed tray 22 one by one, and a pair of transport rollers 24 that conveys the sheets P sent from the paper feed tray 22. is doing. The transport roller pair 24 includes a transport roller 24-1 and a transport roller 24-2 that is disposed opposite to the transport roller 24-1 and is driven to rotate, and these are brought into contact with each other at a predetermined pressure by an unillustrated urging means.

A separation slope 21 is arranged on the downstream side of the sheet feeding tray 22 in the sheet feeding direction, and the sheets P stacked on the paper feeding tray 22 are separated from the separation slope 21 and the feeding roller 1. , 11 are separated one by one and sent out. The upper surface of the conveyed sheet P is guided by the upper surface conveyance guide 25, and the lower surface of the sheet is guided by the lower surface conveyance guide 26.

The image forming apparatus 110 has the above-described sheet feeding device 100 and the image forming section 60, and the photosensitive drum 52 is arranged in the image forming section 60. The photosensitive drum 52 and an image developing unit (not shown) are integrally held by a toner cartridge 53, and above the photosensitive drum 52, a laser scanner 54 that forms an electrostatic latent image on the photosensitive drum 52. Are arranged.

In the above, the sheet P sent out from the paper feed tray 22 is further conveyed in the feeding direction by the rotation of the conveying roller pair 24, and is sent to the nip portion between the photosensitive drum 52 and the transfer roller 55. At this time, an electrostatic latent image is formed on the photosensitive drum 52 by the laser scanner 54, the electrostatic latent image is developed into a toner image in the toner cartridge 53, and the toner image is transferred to the transfer roller 5.
5 is transferred to the sheet P. The transferred toner image is fixed on the sheet P by the fixing device 56. Further, the sheet P after fixing has a sheet discharge roller pair 57 and a sheet discharge roller pair 5
8 and the sheet P is discharged to the outside of the image forming apparatus, and the discharged sheet P is stacked on the sheet discharge tray 59.

[First Embodiment] First, a sheet feeding apparatus 10 in which the driving systems of the feeding rollers 1 and 11 are independent of each other.
0A will be described.

In FIGS. 2 and 3, a sheet feeding tray (sheet accommodating means) 22 in which the sheets P are stacked and accommodated is provided with a separation slope 21 for delivering the sheets P one by one at the downstream end in the sheet feeding direction. Are arranged. This separation slope 21
A conveyance guide 23 is arranged on the front side facing the conveyance guide 23, and a conveyance roller pair 24 is provided on the downstream side of the conveyance guide 23 in the sheet conveyance direction. A drive shaft 3 connected to a drive device (not shown) is provided above the paper feed tray 22 and at a position separated from the separation slope 21 on the upstream side in the sheet conveying direction with a predetermined distance in the front and rear. , 13 are arranged in parallel in a direction substantially orthogonal to the sheet conveying direction.

The drive gear 4 is attached to one of the drive shafts 3.
Are integrally fixed, and when the drive gear 4 rotates, a plurality of idler gears (4
The power is sequentially transmitted to a gear train (power transmission mechanism) composed of individual pieces, and the driving force is further transmitted to the roller gear 9.
The gear train has idler gears 5 to 8 that mesh with each other, the first idler gear 5 meshes with the drive gear 4, and the last idler gear 8 meshes with the roller gear 9. Then, the power transmitted to the roller gear 9 is transmitted to the feeding roller 1 (first feeding means) via the paper feed shaft 10 which is integral with the roller gear 9, and the feeding roller 1 is shown in FIG. By rotating around, the sheets P stacked on the paper feed tray 22 are fed one by one from the top. The gear train described above is held by a support arm (support member) 2 so as to be vertically swingable about a drive shaft 3.

Similarly, a drive gear 14 is integrally fixed to the other drive shaft 13, and when the drive gear 14 rotates, a plurality of idler gears (four) are arranged adjacent to the drive gear 14. The power is sequentially transmitted to the gear train (power transmission mechanism) consisting of, and the driving force is further transmitted to the roller gear 19. The gear train is an idler gear 1 that meshes with each other.
5-18, the first idler gear 15 is the drive gear 1
4 and the last idler gear 18 meshes with the roller gear 19. Then, the power transmitted to the roller gear 19 is transmitted to the feeding roller (second feeding means) 11 via the paper feed shaft 20 integrated with the roller gear 19.
By rotating the feeding roller 11 clockwise in FIG. 3,
The sheets P stacked on the paper feed tray 22 are fed one by one from the top. The gear train described above is held by a support arm (support member) 12 so as to be vertically swingable about a drive shaft 13.

The operation of the feeding rollers 1 and 11 at the time of feeding the sheet will be described.

When power is applied to the drive shafts 3 and 13 at substantially the same time from an independent drive device (not shown), the feeding rollers 1 and 11 start the sheet feeding operation at substantially the same time. At this time, when feeding a sheet with a weak waist (rigidity) such as thin paper,
The feeding roller 1 closer to the separation slope 21 feeds the sheets P one by one while preventing double feeding of the sheets P, and the separation slope 2
The feeding roller 11 that is farther from 1 plays a role of assisting the conveyance of the sheet P that the feeding roller 1 has separated.

When a sheet P having a high rigidity such as thick paper is fed, the bending of the sheet P is small only by the feeding roller 1 closer to the separation slope 21, and the feeding roller 1 bites into the sheet P. There is a risk that it will be locked.
However, at this time, by the feeding roller 11 distant from the separation slope 21 feeding the sheet P from the rear,
By preventing the feeding roller 1 from biting, the feeding roller 1 is ready for feeding. Then, in this case, by setting the initial pressure of the feeding roller 1 to be low, it is possible to easily bend a thick sheet and enable stable feeding.

Further, the above-mentioned gear train includes the support arms 2,
The sheet 12 is held so as to be vertically swingable about the drive shafts 3 and 13, and the feeding rollers 1 and 11 are lifted in association with the bending of the sheet P to be fed. P can be delivered without stress.

In this embodiment, the drive shafts 3, 13 are
Although the configuration in which the power is transmitted to the feeding rollers 1 and 11 by the gear coupling mechanism has been described, the configuration is not limited to this, and the configuration may be such that the power is transmitted by a belt transmission mechanism, for example.

Next, a sheet feeding apparatus 100B having a single driving system for the feeding rollers 1 and 11 will be described.

In FIGS. 4 and 5, a drive gear 27 is integrally fixed to the drive shaft 3, and the drive gear 27 rotates to cause a plurality of adjacent idler gears (4
The power is sequentially transmitted to a gear train composed of individual pieces, and the drive transmission is further performed to the roller gear 32. The gear train has idler gears 28 to 31 that mesh with each other. The first idler gear 28 meshes with the drive gear 27, and the last idler gear 31 meshes with the roller gear 32. Then, the power transmitted to the roller gear 32 is transmitted to the feeding roller 1 via the paper feed shaft 10 integrated with the roller gear 32, and the feeding roller 1 rotates clockwise in FIG. The sheets P stacked on the paper tray 22 are fed one by one from the top.

Further, the idler gear 29 in the middle is also meshed with an idler gear 33 of a different system from the above, and the driving force is transmitted from the idler gear 33 to the idler gear 34, and further from the idler gear 34 to the roller gear 35.
Then, the power transmitted to the roller gear 35 is transmitted to the feeding roller 11 via the paper feed shaft 20 integrated with the roller gear 35, and the feeding roller 11 rotates clockwise in FIG. Similar to the feed roller 1, the sheets P stacked on the paper feed tray 22 are fed one by one from the top.

At this time, the feeding roller 1 and the feeding roller 11
The number of idler gears of two systems that mesh with the intermediate idler gear 29 is set to the same number (two) so that they rotate in the same direction at substantially the same time. In addition, the series of two-system gear trains described above are held so as to be vertically swingable about the drive shaft 3 by the support arms 26 arranged as a pair of left and right in the seat width direction.

According to the present embodiment, the feeding rollers 1, 1
Since only one driving device is provided and the power transmission path can be simplified, a compact and inexpensive sheet feeding device 100B can be obtained.

Further, a sheet feeding apparatus 100C having one driving system for the feeding rollers 1 and 11 will be described.

In FIGS. 6 and 7, the drive transmission from the drive gear 14 to the roller gear 19 is the same as that shown in FIGS. 2 and 3, and the description thereof will be omitted. In the present embodiment, the feeding roller 11 driven by the roller gear 19 rotates clockwise in FIG. 7, but at this time, the feeding roller 1 also rotates clockwise through the idler gears 37 to 39 and the roller gear 9. Start spinning.

Power is transmitted from a driving device (not shown) to the two feeding rollers 1 and 11 arranged at different positions on the upstream side and the downstream side in the sheet feeding direction with respect to the separation slope 21. Then, the rotation starts in the same direction at substantially the same time through the gear train including the plurality of idlers described above.

In the present embodiment, the feeding rollers 1, 1
Since 1 is arranged at a position different in the sheet feeding direction with respect to the separation slope 21, when feeding a sheet having a low stiffness (rigidity) such as thin paper, as described in the description of FIGS. 2 and 3,
The feeding roller 1 closer to the separation slope 21 feeds the sheets P one by one while preventing double feeding of the sheets P, and the separation slope 2
The feeding roller 11 that is farther from 1 plays a role of assisting the conveyance of the sheet P that the feeding roller 1 has separated. When feeding a sheet P having a large rigidity such as thick paper, the separation slope 2
1, the feeding roller 11 located far from the sheet P
By feeding the sheet, the feeding roller 1 is prevented from biting into the sheet so that the sheet can be fed.

In the present embodiment, by using one drive system for the feeding rollers 1 and 11, control by a single motor is possible and the number of parts is reduced, so that the manufacturing cost can be suppressed. It will be possible.

[Second Embodiment] In the present embodiment,
A sheet feeding apparatus 100D for selecting one of the first and second feeding rollers 1 and 11 according to the type of sheet and feeding the sheet by the selected one feeding roller. Will be described.

As a method of selecting one of the first and second feeding rollers 1 and 11, as shown in FIG. 8, for example, the user manually selects the selecting means 50 according to the type of the sheet P to be used. A method of performing a selection operation to select either one of the first and second feeding rollers 1 and 11, and the type of the sheet P is automatically detected by a sensor or the like, and the selection unit 50 is based on the detection signal. , First and second feeding rollers 1,
A method of automatically selecting any one of 11 can be considered.

FIG. 8 is based on the detection signal from the sensor.
An embodiment is shown in which the first and second feeding rollers 1 and 11 are automatically selected. That is, in this embodiment, a sensor flag 40 that is rotatably held is provided in the vicinity of the first feeding roller 1, and one end of the sensor flag 40 has a substantially central portion of the separation slope 21 in the sheet width direction. It penetrates through the hole 21a formed in and the other end is housed in the photo sensor 41 attached to the support arm 2. The photo sensor 41 is connected to the selection means 50, and the detection signal of the photo sensor 41 is input to the photo sensor 41.

In this case, first, the first feeding roller 1 is selected, and after the sheet P starts to be fed by the first feeding roller 1, the sheet P is set to the sensor flag 4
When 0 is pushed up, the optical path of the photo sensor 41 is cut off, the sheet P passes through the separation slope 21, and after the sheet P passes, the sensor flag 40 is set within the photo sensor 41 again. At sheet P
It is judged that the feeding has been completed.

By the way, a sheet P having a large rigidity such as thick paper
As described above, when the feeding roller 1 closer to the separation slope 21 bites into the sheet P and is locked, the off / on signal of the photo sensor 41 causes the selection unit 5 to feed the sheet.
It will not be sent to 0. Therefore, in this case, the selection unit 50 determines that the feeding is defective, and the drive transmission to the feeding roller 1 is continued, and at the same time, the selection unit 50 immediately transmits the drive to the second feeding roller 11. Control to start is performed.

As described above, according to the present embodiment, the sheet P, which has once failed to be fed, is automatically fed by the second feeding roller 11. Further, for example, by selectively driving the feeding rollers 1 and 11 depending on the type of the sheet P, it is possible to widen the range of the feeding range.

[Third Embodiment] In the present embodiment,
The sheet feeding device 100 is configured such that the feeding timings of the two feeding rollers 1 and 11 provided on the upstream side in the sheet feeding direction from the separation slope 21 are shifted with respect to time.
A will be described. 2 and 3 used in the first embodiment are used for the drawing.

That is, after power is first transmitted from the driving device (not shown) to the feeding roller 1, the power is also transmitted to the feeding roller 11 after a lapse of a predetermined time by the timer (delay means) 51. As a result, when the sheet feeding is started, only the feeding roller 1 closer to the separation slope 21 is operating, so that the feeding operation is started while the thin sheets are reliably separated one by one. Then, after a lapse of a certain time after the power is transmitted to the feeding roller 1, the power is transmitted to the feeding roller 11 farther from the separation slope 21 to start the operation, whereby the feeding roller 11 is fed. It plays an auxiliary role to the feeding operation of the feeding roller 1, and feeding with higher feeding force is performed.

When a thick sheet is fed, the feeding roller 1 closer to the separation slope 21 is operated first, so that the leading end of the sheet P cannot be flexed with the separation slope 21. However, even if the feeding roller 1 alone cannot feed the toner, for example, by incorporating a torque limiter into the feeding roller 1, when the torque exceeds a certain level, the feeding roller 1 Spins idle. And
Then, after a lapse of a certain period of time, a driving device (not shown) is controlled to drive the feeding roller 11 that is far from the separation slope 21 to reliably feed the thick sheet while bending it. This makes it possible to support a wide range of media from thin sheets to thick sheets.

As a specific control method in this case, as described above, the timer 51 is set to the second feeding roller 1
Two feeding rollers other than the method of mounting the first feeding roller 1 on the first feeding roller 1 and driving the second feeding roller 11 after a predetermined time elapses after the first feeding roller 1 is driven. A method is conceivable in which the motors 1 and 11 are independently driven and controlled by two motors. Further, the first and second feeding rollers 1 and 11 are driven by one driving device, and a solenoid, a clutch, or the like is arranged between the driving device and the second feeding roller 11, and The power is not transmitted to the second feeding roller 11 for a predetermined time after the feeding roller 1 is driven, and after the predetermined time has elapsed, the clutch or the like is connected to drive the second feeding roller 11. It is possible to control it.

[0050]

As described above, according to the present invention,
By providing the first feeding unit and the second feeding unit that are arranged separately from each other on the upstream side in the sheet feeding direction with respect to the separation slope, it is possible to prevent double feeding of thin sheets. At the same time, it is possible to prevent defective feeding of thick sheets.

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming apparatus including a sheet feeding device according to the present invention.

FIG. 2 is a sheet feeding device (drive 2 according to the first embodiment;
It is a top view of a schematic structure of (system).

FIG. 3 is a side view of the above.

FIG. 4 is a sheet feeding device (drive 1 according to the first embodiment.
It is a top view of a schematic structure of (system).

FIG. 5 is a side view of the above.

FIG. 6 is a sheet feeding device (drive 1 according to the first embodiment.
It is a top view of a schematic structure of (system).

FIG. 7 is a side view of the above.

FIG. 8 is a side view of a feeding schematic configuration of a sheet feeding device according to a second embodiment.

FIG. 9 is a side view of a sheet feeding device in a conventional example.

FIG. 10 is a side view showing an enlarged main part of the above and showing the action of force during sheet feeding.

[Explanation of symbols]

1 Feeding Roller (First Feeding Means) 11 Feeding Roller (Second Feeding Means) 2, 12, 26, 36 Support Arm (Supporting Member) 3, 13 Drive Shafts 4, 14, 27 Drive Gear 5 , 6, 7, 8 Idler gear (power transmission mechanism) 9, 19, 32, 35 Roller gear (power transmission mechanism) 10, 20 Paper feed shaft 15, 16, 17, 18 Idler gear (power transmission mechanism) 21 Separation slope 22 Paper feed Tray (sheet storing means) 23 Conveying guide 24 Conveying roller pairs 28, 29, 30, 31 Idler gear (power transmission mechanism) 33, 34 Idler gear (power transmission mechanism) 37, 38, 39 Idler gear (power transmission mechanism) 40 Sensor flag 41 Photo sensor 50 Selection means 51 Timer (delay means) P sheet 52 Photosensitive drum 60 Image forming units 100, 100A, 100B, 100C, 100D
Sheet feeding apparatus 110 Image forming apparatus

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takayoshi Inoue             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 3F343 FA02 FB01 FC01 FC03 GA01                       GB01 GC01 GD01 JA18 JD08                       KB05 LA04 LA15 LA16 LC19                       LD24 LD28 MC22

Claims (6)

[Claims] 1. A sheet feeding device comprising: a sheet storing means for storing a sheet; and a separation slope which is arranged on the downstream side of the sheet storing means in the sheet feeding direction and separates the fed sheets one by one. A first feeding unit and a second feeding unit that are arranged separately on the upstream side in the sheet feeding direction with respect to the separation slope and that feed the sheet stored in the sheet storing unit in the feeding direction. A sheet feeding device provided with the above. 2. A support member, wherein the first feeding means and the second feeding means are connected to a drive shaft via a power transmission mechanism, and one end of which is rotatably attached to the drive shaft. The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is supported on the other end side of the sheet. 3. A selection means for selecting at least one of the first feeding means and the second feeding means,
3. The sheet feeding apparatus according to claim 1, wherein power can be transmitted to the feeding means on the selected side. 4. A delay means for transmitting power to the second feeding means after a lapse of a predetermined time from the start of power transmission to the first feeding means. The sheet feeding device according to 1 or 2. 5. The power transmission path of the power transmission mechanism is branched midway, and the first feeding means or the second feeding means is provided on the terminal end side of each of the branched power transmission paths. The sheet feeding device according to claim 2, wherein: 6. A sheet feeding device according to any one of claims 1 to 5, and an image forming section for forming an image on a sheet fed from the sheet feeding device. An image forming apparatus characterized by the above.