JPH11165895A - Sheet material feeding device and image processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce pressure fluctuation of a retard roller at the time of conveying sheet material so as to enlarge an appropriate feeding area in an actual machine. SOLUTION: A sheet material feeding device for feeding sheet material while separating the sheet material sheet by sheet has a feed roller 1 for conveying sheet material, a retard roller 2 rotated in the reverse direction to the rotating direction of the feed roller 1 so as to separate one sheet material, a feed roller driving motor 3 for rotating driving the feed roller 1, a retard roller driving motor 4 for rotating driving retard roller 2, and a control means 19 for controlling driving of the respective motors 3, 4. It is so constituted that the driving start timing of the retard roller 2 is later than the driving start timing of the feed 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 for sequentially feeding sheet materials one by one, and more particularly, to a sheet feeding apparatus used in an image processing apparatus such as a printer or a copying machine. It concerns the device.

[0002]

2. Description of the Related Art Conventionally, as a sheet material feeding device used in an image processing apparatus such as a copying machine, there is a sheet material feeding device 201 as shown in FIG. This sheet material feeding device 201 includes a processing unit (for example, a processing unit of an image processing device such as a copying machine).
The sheet materials 202 are sequentially supplied one by one to an image forming unit of a copying machine. As shown in FIG.
1 is a pickup roller 205 that feeds the uppermost sheet material 202 one by one from a sheet material storage device 203 in which a plurality of sheet materials 202 are stacked and stored on a loading table (not shown); The feed roller 20 transports the sheet material 202 fed from the sheet material storage device 203 toward the processing section (the direction of arrow b in the drawing).
6, when there are a plurality of sheet materials 202 which are arranged opposite to the feed roller 206 and are fed from the sheet material storage device 203, the sheet material 202 is rotated in a direction opposite to the rotation direction of the feed roller 206 and one sheet material is rotated. There are provided a retard roller 207 for separating the sheet material 202 and a pair of transport rollers 209 for transporting the separated sheet material 202 to the processing section.

A guide 211 is disposed in a sheet material passage area 210 between the pickup roller 205, the feed roller 206, and the retard roller 207.
Guides 212 are arranged between the 206 and the retard roller 207 and the transport roller pair 209 and between the transport roller pair 209 and the processing unit, and the sheet material 202 is guided and transported respectively.

The feed roller 206 and the retard roller 207 are driven by a drive transmission device 213 shown in FIG. As shown in FIG. 6, the drive transmission device 213 includes a feed roller shaft 215 that supports the feed roller 206, a retard roller shaft 216 that supports the retard roller 207, and a retard roller connected to the retard roller shaft 216. The drive shaft 217 is provided substantially in parallel. Retard roller shaft
Reference numeral 216 is supported by a swingable support member (not shown) and can be brought into and away from the feed roller shaft 215 in parallel. A coupling 219 and a torque limiter are provided between the retard roller shaft 216 and the retard roller drive shaft 217.
220 are located. Further, a driving force transmitted from a main drive unit (not shown) via a drive input belt 221 is applied to an end of the feed roller shaft 215.
5 is provided with an electromagnetic clutch 222. Between the feed roller shaft 215 and the retard roller shaft 217, a retard drive belt 223 that transmits the rotational driving force transmitted to the feed roller shaft 215 to the retard roller drive shaft 217 is wound. In addition, coupling 219
Is for transmitting the drive from the retard roller drive shaft 217 to the retard roller shaft 216 even if the retard roller 207 is displaced.

The driving of the feed roller 206 and the retard roller 207 by the drive transmission device 213 will be described. Rotational driving force provided from a main drive unit (not shown) is transmitted to a drive input belt 221 and input to a pulley 225 provided on an armature portion of an electromagnetic clutch 222 that is ON-OFF controlled in accordance with a sheet feeding timing. Here, since the feed roller shaft 215, the retard roller drive shaft 217, and the retard roller shaft 216, which rotate integrally with the rotor portion of the electromagnetic clutch 222, are connected by the retard drive belt 223, the feed roller shaft 215 and the retard roller shaft 216 are connected. Further, the retard roller drive shaft 217 rotates in the same direction, and the feed roller 206 and the retard roller 207 are rotationally driven in synchronization with the sheet feeding timing ON.

[0006] The sheet material 202 is driven by the drive transmission device 213.
Roller 207 is fed one by one in the feeding direction (the direction of arrow b shown in FIGS. 5 and 6).
The torque limiter 220 idles due to the frictional force between the sheet 206 and the sheet member 202, and rotates in a direction (feeding direction) opposite to the driving rotation direction of the retard roller 217. Further, when a plurality of sheet materials 202 are fed, the plurality of sheet materials 202 are not affected by the frictional force between the retard roller 207 and the sheet material 202.
Since the frictional force between them is small, the torque limiter 220 does not run idle, and the retard roller 207 is driven by the retard roller drive shaft 21.
7 rotates in the same direction as the rotational drive direction (the direction opposite to the feeding direction). As a result, the feed roller 206 side of the plurality of fed sheet materials 202, that is, the uppermost sheet material 202 and the other sheet materials 202 are separated, and the multi-feed of the sheet materials 202 to the processing unit is performed. To prevent it.

Next, a description will be given of a theoretical formula that satisfies the conditions for feeding and separating the sheet material 202 by the sheet material feeding device 201 having the above-described configuration. In the following equation, μ _AP is the friction coefficient between the pickup roller 205 and the sheet material 202, μ _BP is the friction coefficient between the feed roller 206 and the sheet material 202, μ _CP is the friction coefficient between the retard roller 207 and the sheet material 202, μ _APP is the coefficient of friction between the pick-up roller 205 and the sheet material 202 under the pressurizing section, and μ _BPP is the feed roller 206 and the retard roller 20.
7, N is the pressure of the retard roller 207, T is the idling torque of the torque limiter 220, r is the radius of the retard roller 207, and W is the pressure of the pickup roller 205. .

[0008] _{N> T / rμ BP + (} μ APP -μ AP) W / μ BP ... (1) N <T / rμ BPP -2μ APP W / μ BPP ... (2) N <T / rμ CP ... ( 3)

The above equation (1) satisfies the feeding condition, (2) satisfies the separation condition, and (3) satisfies the revolving condition of the retard roller 207. If the same sheet material is used in the above equation, the friction coefficient of each roller pressing portion does not vary so much. Therefore, the friction coefficient is given by μ _APP ≒ μ _BPP
= Μ _PP , the above equations (1) and (2) become the following equations (4) and (5), respectively.

N> T / rμ _BP + (μ _PP −μ _AP ) W / μ _BP (4) N <T / r μ _PP -2W (5)

Here, the relations of the above equations (3), (4) and (5) are expressed by the pressing force N of the retard roller 207 and the torque limiter 22.
FIG. 7 shows a graph obtained by using the idling torque T of 0 as a parameter. In the figure, a hatched portion is a feeding area in which the sheet feeding as described above is properly performed. In order to enlarge this feeding area (shaded area), increase the coefficient of friction between each roller and the sheet material or use a pickup roller.
It is necessary to reduce the pressurizing force of the roller 205 and the feed condition is set under the condition of increasing both the pressing force N of the retard roller 207 and the idling torque T of the torque limiter 220 (upper right direction in the figure). It can be understood that the feeding area (shaded area) becomes wider. However, if the idling torque of the torque limiter 220 is excessively increased, the load torque in driving the roller increases, so that the proper feeding area (shaded area)
(The upper right limit in the figure) is also subject to some restrictions.

[0012]

With the recent increase in the speed of image processing apparatuses and diversification of sheet materials, it has become difficult to set an almighty feeding area. That is, it has become difficult to achieve both the prevention of double feeding of various sheet materials beforehand and the sufficient securing of the durability of the feed roller and the retard roller. Specifically, in order to prevent double feed, the idling torque of the torque limiter may be increased or the pressing force of the retard roller may be reduced, but if this is turned over, this configuration is equivalent to the feed roller and the retard roller. It shifts to shorten the durability.

Further, in the above-described theoretical formula of the appropriate feeding area, the idling torque of the torque limiter and the pressing force of the retard roller are presumed to be only static values. "), The ripple of the torque generating source accompanying the torque limiter and the pressure fluctuation at the time of conveying the sheet material accompanying the retard roller always occur. Therefore, the proper feeding area obtained from the actual machine can be obtained from the theoretical formula. Usually, it becomes smaller than the appropriate feeding area.

Therefore, as a countermeasure against these problems, in a recent feeding apparatus, a torque generating source of a torque limiter is changed to a non-contact type using a magnet to reduce a ripple of a sliding portion, or a material of a retard roller is synthesized. An improved method has been used in which an elastic body such as rubber or sponge is used to reduce pressure fluctuations caused by vibration during conveyance of a sheet material.

However, regarding the fluctuation of the pressure of the retard roller, at present, no clear countermeasure method has been established for a plurality of feeding devices having different support mechanisms, pressure mechanisms and the like for the retard roller.

FIG. 8 shows an example of the pressure fluctuation of the retard roller in the actual machine. In the figure, the abscissa represents the time in sheet conveyance (Ts is the time when the feed roller and the retard roller start driving), and the ordinate represents the pressing force (retard pressure) of the retard roller. As is apparent from the figure, it is understood that the fluctuation of the retard pressure at the start of driving the roller is dominant. This is because the shock generated by the rotation of the feed roller driven in the sheet material conveyance direction and the retard roller driven in the sheet material return direction in different directions,
This is due to the result of increased ON shock when both roller drives are simultaneously connected.

Suppose that the driving of the sheet material returning direction is not input to the retard roller (a structure in which a plurality of sheet materials conveyed by the retard roller is restrained only by the restraining force of the outer peripheral surface of the retard roller generated from the idling torque of the torque limiter). It has been experimentally proved that the shock at the start of driving described above is considerably reduced. However, in this configuration, since the plurality of sheets sandwiched between the nip portion between the feed roller and the retard roller cannot be returned in the direction opposite to the transport direction, it cannot be employed as a means for expanding the above-described appropriate feeding area. It has become a configuration.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce fluctuations in the pressure of a retard roller during the conveyance of a sheet material and to enable an appropriate feeding area in an actual machine to be expanded.

[0019]

To achieve the above object, a typical configuration of the present invention is a feed roller for conveying a sheet material in a sheet material feeding apparatus for sequentially separating and feeding the sheet material one by one. A retard roller that rotates in a direction opposite to the rotation direction of the feed roller to separate the sheet into a single sheet material; a feed roller driving unit that rotationally drives the feed roller; and a rotational roller that drives the retard roller. And a control means for controlling the driving of each of the driving means, wherein control is performed such that the driving start timing of the retard roller is different from the driving start timing of the feed roller.

Specifically, for example, the control is performed such that the drive start timing of the retard roller is later than the drive start timing of the feed roller.

Further, the present invention is characterized in that the relationship between the peripheral speed V _{1 of the} retard roller and the peripheral speed V ₂ of the feed roller is such that V ₁ ≦ V ₂ .

Further, the drive start control of the drive means is a slow-up control in which the drive is gradually started from a drive OFF state until a predetermined speed is reached.

According to the above configuration, the fluctuation of the pressure of the retard roller during the conveyance of the sheet material is reduced, so that the appropriate feeding area in the actual machine can be expanded.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sheet feeding apparatus to which the present invention is applied will be specifically described below with reference to the drawings. In the following description, a sheet material feeding device used in an image processing device is exemplified.

[First Embodiment] A sheet material feeding apparatus according to a first embodiment will be described in detail with reference to the drawings.
In this embodiment, a sheet material feeding device used in a copying machine as an image processing device is illustrated.

In the following description, a copying machine as an image processing apparatus will be described, and then a sheet feeding apparatus will be described.

First, a schematic configuration of the image processing apparatus will be described with reference to FIG. The image processing apparatus includes a feed deck 12 on which a large amount of sheet materials S are loaded and stored on one side of the image processing apparatus main body 11, and a predetermined amount of sheet materials S loaded on a lower portion in the image processing apparatus main body 11. Multiple feed cassettes stored
It has 13 and 14.

The feed deck 12 serving as a feed unit for feeding the sheet material S, and the feed units 15, 15 of the retard separation type, are provided at the installation sites of the respective feed cassettes 13, 14.
16, 17 are provided. This feeding device will be described later in detail.

When the sheet material S in the feeding deck 12 and the feeding cassettes 13 and 14 is fed by the feeding devices 15, 16 and 17, first, the registration roller pair stopped rotating.
It is sent to 18, where the skew state is corrected.

Next, the photosensitive drum 21 and the transfer charger 22 are connected to each other by a registration roller pair 18 which rotates at a timing with respect to a latent image formed on the photosensitive drum 21 constituting an image forming unit as a processing means. The toner image on the photosensitive drum 21 is transferred here.

Thereafter, the sheet material S is sent to the fixing device 24 by the transport belt 23, and a fixing process for fixing the transferred toner image on the sheet surface is performed.

The present image processing apparatus has a duplex copying mode for performing duplex copying on the sheet material S and a multiplex copying mode for performing multiple copying. In the normal copying mode (single-side copying mode), the sheet after the fixing process is performed. The material S is discharged onto a discharge tray 27 outside the machine by a pair of inner discharge rollers 26.

In the case of the double-sided copy mode and the multiple copy mode, the pair of inner discharge rollers 25 or the pair of switchback rollers 29 temporarily place the sheet on the intermediate tray 31 via the re-feeding path 28 and the double-sided conveying path 30. It is loaded and stored.

Then, the sheet material S stored on the intermediate tray 31 is again conveyed to the registration roller pair 18 for image formation by the re-feeding device 32, and thereafter discharged out of the apparatus through the same process as for one-sided copying. Is done.

Next, the feeding devices 15, 16, 17 and the re-feeding device 32 as sheet feeding devices to which the present invention is applied will be described. Here, the configuration of the feeding device 15 will be described as an example, but it goes without saying that the other feeding devices 16, 17, and 32 may have the same configuration as needed.

The present sheet material feeding device 15 sequentially separates and feeds the sheet materials one by one toward the above-mentioned image forming section, and feeds a plurality of sheet materials S stacked and stored. A pickup roller 10 for feeding the uppermost sheet material S one by one from a deck 12;
A feed roller 1 that conveys the sheet material S fed from the feed deck 12 by the feed roller 10 into the image processing apparatus main body, and a sheet material S that is disposed to face the feed roller 1 and fed from the feed deck 12 is provided. Feed roller 1 for multiple sheets
And a retard roller 2 for separating the sheet S into a single sheet S by rotating in a direction opposite to the rotation direction of the sheet.

Further, as shown in FIG.
, A retard roller shaft 6 for supporting the retard roller 2 and a retard roller driving shaft 7 connected to the retard roller shaft 6 are provided substantially in parallel. The retard roller shaft 6 is supported by a swingable support member (not shown) and can be brought into contact with and separated from the feed roller shaft 5 in parallel. Also, the retard roller shaft 6
A coupling 8 and a torque limiter 9 are disposed between the motor and the retard roller drive shaft 7.

The coupling 8 is for transmitting the drive from the retard roller driving shaft 7 to the retard roller shaft 6 even when the retard roller 2 is displaced.

The end of the feed roller shaft 5 and the end of the retard roller drive shaft 7 connected to the retard roller shaft 6 are provided as drive means whose driving is independently controlled by a control means 19. Motors 3 and 4 are provided.

The driving of the feed roller 206 and the retard roller 207 will be described. The feed roller shaft 5, the retard roller shaft 6, and the retard roller drive shaft 7 rotate in the same direction by the motors 3, 4, respectively. Here, as shown in FIG.
At time N, the retard roller 2 is driven to rotate later than the drive start timing of the feed roller 1.

When the sheet material S is fed one by one in the transport direction (the direction of the arrow b shown in FIG. 1), the retard roller 2 is driven by the torque limiter 9 by the frictional force between the feed roller 1 and the sheet material S. It idles and rotates in the direction opposite to the drive rotation direction of the retard roller 2 (transport direction). When a plurality of sheets S are fed, the retard roller 2
Since the frictional force between the plurality of sheet materials S is smaller than the frictional force between the sheet material S and the sheet material S, the torque limiter 9 does not idle and the retard roller 2 is driven by the retard roller drive shaft 7.
Rotate in the same direction as the rotational drive direction (the direction opposite to the transport direction).

As a result, the feed roller 1 side, that is, the uppermost sheet material S and the other sheet materials S in the plurality of fed sheet materials S are separated from each other, and the sheet materials are transferred into the image processing apparatus main body. The double feed of S is prevented.

Here, as can be seen from FIG. 1, the feed roller 1 and the retard roller 2 can be driven and controlled independently by a feed roller drive motor 3 and a retard roller drive motor 4, respectively. As described above, the feed roller 1 is driven to rotate when the paper feed timing is ON, but the retard roller 2 is driven to rotate later than the drive start timing of the feed roller 1 (see FIG. 2). ).

FIG. 3 shows how the pressure of the retard roller fluctuates when the above-described drive control is performed. In the drawing, T _F indicates the start of driving of the feed roller, and T _R indicates the start of driving of the retard roller. As can be seen from the figure, by performing the drive control as described above, the pressure fluctuation of the retard roller 2 at the start of driving is reduced as compared with the conventional apparatus (see FIG. 8). This is because, as described above, the feed roller 1 that is driven to rotate in the sheet material conveyance direction and the retard roller 2 that is driven to rotate in the sheet material return direction (the direction opposite to the conveyance direction) are shifted by shifting both roller drive start timings. This is because shocks caused by rotation in different directions and shocks at the time of driving connection are reduced.

Incidentally, the delay amount of the drive start timing of the drive motor 4 of the retard roller 2 is, for example, about 20 to about 20 in a feeding apparatus in which the sheet material conveying speed is about 500 mm / s.
It has been confirmed that setting the time to about 30 ms is an optimum system for minimizing fluctuations in retard pressure. The above numerical values are illustrative and do not limit the present invention.

As described above, by performing the control in which the drive start timing of the retard roller 2 is later than the drive start timing of the feed roller 1, the fluctuation in the pressure of the retard roller 2 during the conveyance of the sheet material is reduced. It is possible to expand the appropriate feeding area in the actual machine.

Further, as a measure against a shock at the start of driving,
The relationship between the circumferential speed V ₁ of the retard roller 2 and the circumferential speed V ₂ of the feed roller 1 is configured such that V ₁ ≦ V _2, also driven OFF the drive start control of the motor 3 and 4
It is also an effective means to perform a slow-up control for gradually starting from the state until reaching a predetermined speed.

[Other Embodiments] In the above-described embodiment,
Although the configuration in which the drive start timing of the retard roller is controlled to be later than the drive start timing of the feed roller has been exemplified, the present invention is not limited to this.
For example, a configuration in which the drive start timing of the retard roller is controlled earlier than the drive start timing of the feed roller may be performed, and the same effect can be obtained.

In the above-described embodiment, a copying machine is exemplified as an image processing apparatus. However, the present invention is not limited to this. For example, other image processing apparatuses such as a scanner, a printer, and a facsimile apparatus may be used. The same effect can be obtained by applying the present invention to a sheet material feeding device used in the image processing apparatus.

In the above-described embodiment, the sheet feeding apparatus detachably attached to the image processing apparatus main body has been exemplified. However, the present invention is not limited to this.
For example, a sheet feeding device integrally provided in the image processing apparatus may be used, and similar effects can be obtained by applying the present invention to the sheet feeding device.

Further, in the above-described embodiment, the sheet material feeding apparatus for feeding the sheet material such as the recording paper as the recording object to the image forming unit as the processing means has been exemplified, but the present invention is not limited to this. For example, the same effect can be obtained by applying the present invention to a sheet material feeding device that feeds a sheet material such as a document to be read to a reading unit serving as a processing unit.

In the above-described embodiment, the electrophotographic method is exemplified as the recording method. However, the recording method is not limited to this, and another recording method such as an ink jet method may be used.

[0053]

As described above, according to the present invention,
Since the control is performed such that the drive start timing of the retard roller is different from the drive start timing of the feed roller, specifically, for example, the drive start timing of the retard roller is greater than the drive start timing of the feed roller. Since the slow control is performed, the fluctuation of the pressure of the retard roller during the conveyance of the sheet material is reduced, and the appropriate feeding area in the actual machine can be expanded.

Further, as a countermeasure against a shock at the start of driving,
The relationship between the peripheral speed V1 of the retard roller and the peripheral speed V2 of the feed roller is such that V1 ≦ V2.
It is also effective that the drive start control of the drive means is slow-up control in which the drive is gradually started from a drive OFF state until a predetermined speed is reached.

The above-described effects are obtained by the support mechanism of the retard roller,
Since the pressurizing mechanism is effective in a plurality of feeding devices different from each other, it can be said that the versatility is very high from the viewpoint of application of technology.

Further, as a result of improving the reliability of the feeding device over a wide range from low speed to high speed, it is possible to provide an image processing device having high potential in sheet material conveyance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a feeding device according to the present invention.

FIG. 2 is a drive signal diagram of the feeding device according to the present invention.

FIG. 3 is a pressure fluctuation diagram of a retard roller of the sheet feeding device according to the present invention.

FIG. 4 is a schematic cross-sectional view illustrating a schematic configuration of an image processing apparatus.

FIG. 5 is a sectional view of a conventional feeding device.

FIG. 6 is a perspective view of a conventional feeding device.

FIG. 7 is a conventional feed area diagram.

FIG. 8 is a pressure fluctuation diagram of a retard roller of a conventional feeding device.

[Explanation of symbols]

 S ... sheet material 1 ... feed roller 2 ... retard roller 3, 4 ... motor 5 ... feed roller shaft 6 ... retard roller shaft 7 ... retard roller drive shaft 8 ... coupling 9 ... torque limiter 10 ... pickup roller 11 ... image processing device Main unit 12: Feeding decks 13, 14, Feeding cassettes 15, 16, 17 Feeding device 18: Registration roller pair 19: Control means 21: Photoconductor drum 22: Transfer charger 23: Transport belt 24: Fixing device 25 , 26 ... inner discharge roller pair 27 ... discharge tray 28 ... re-feed path 29 ... switchback roller pair 30 ... double-sided conveyance path 31 ... intermediate tray 32 ... re-feed device

Claims (5)

[Claims] 1. A sheet material feeding apparatus for sequentially separating and feeding sheet materials one by one, comprising: a feed roller for conveying the sheet material; and a sheet material rotated in a direction opposite to a rotation direction of the feed roller. A retard roller that separates the feed roller, a feed roller driving unit that rotationally drives the feed roller, a retard roller driving unit that rotationally drives the retard roller, and a control unit that controls the driving of each of the driving units. A sheet feeder, wherein the drive start timing of the retard roller is controlled differently from the drive start timing of the feed roller. 2. The sheet feeding apparatus according to claim 1, wherein control is performed such that the drive start timing of the retard roller is later than the drive start timing of the feed roller. 3. The method according to claim ₁ , wherein the relationship between the peripheral speed V _{1 of the} retard roller and the peripheral speed V ₂ of the feed roller is V ₁ ≦ V _2. The sheet material feeding device according to the above. 4. The driving start control of the driving means includes a driving O
3. The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a slow-up control that gradually starts from a state of the FF until a predetermined speed is reached. 5. An image processing apparatus having processing means for processing a sheet material and feeding means for feeding the sheet material to the processing means, wherein the feeding means is provided. Any one of
An image processing apparatus comprising the sheet material feeding device according to any one of the preceding claims.