JP2020125170A - Sheet feeding device and image forming apparatus - Google Patents

Abstract

To provide a sheet feeding device and an image forming apparatus capable of properly conveying a preceding sheet even when the following sheet plunges into a first conveying roller while the preceding sheet is conveyed by the first conveying roller.SOLUTION: The sheet feeding device of the invention satisfies the relationship of Lpass>Lmin, when the conveying distance of a sheet between a calling position where a calling roller calls the sheet and a conveying position where a second conveying roller conveys the sheet is defined as Lpass and the length in the conveying direction of the sheet of the minimum size is defined as Lmin, and the circumferential speed of the calling roller is smaller than the circumferential speed of the first conveying roller. The sheet feeding device drives and controls first driving means of the first conveying roller so that the rotation of the first conveying roller is stopped after the conveyed sheet reaches the second conveying roller, and second driving means of the second conveying roller is drive-controlled so that the rotation of the second conveying roller starts after the rotation of the first conveying roller is stopped.SELECTED DRAWING: Figure 10C

Description

The present invention relates to a sheet feeding device and an image forming apparatus such as a copying machine, a multi-function peripheral, and a printer.

An image forming apparatus such as a copying machine, a multi-function peripheral, or a printer calls a stacked sheet (original or recording sheet) by a call-in roller (pickup roller), and the sheet called by the call-in roller is fed by a first conveying roller (feeder). In many cases, a sheet feeding device for feeding from a paper roller) to a second feeding roller (eg, a registration roller) is provided (see, for example, Patent Document 1).

JP, 2003-128278, A JP, 2006-52041, A

In such a sheet feeding device, conventionally, the following problems have been encountered when the sheet is conveyed. Hereinafter, the document G will be described as an example of the sheet.

16A and 16B are schematic diagrams for explaining a conventional inconvenience caused when the document G is conveyed in the sheet feeding apparatus 10X. In FIGS. 16A and 16B, reference numerals 14X and 15X indicate a separation roller and a sheet stacking tray, respectively.

As shown in FIGS. 16A and 16B, in the sheet feeding device 10X, the loaded originals G to G are called by the call-in roller 11X (pickup roller), and the original G called by the call-in roller 11X is conveyed by the first transport roller. The sheets are conveyed one by one from the 12X (paper feed roller) to the second conveyance roller 13X (for example, registration roller). Here, during the conveying operation of continuously conveying the plurality of originals G to G, the pickup roller 11X is lowered (while being in contact with the uppermost original G) and the preceding uppermost original G is kept. Even after (1) is called in, it rotates in the forward rotation direction R1 of the sheet conveying direction H, and immediately follows the next highest document G(2).

Then, while the preceding original G(1) is being conveyed by the first conveying roller 12X, the succeeding original G(2) is directed toward the first conveying roller 12X and is separated from the original (1) and the separation roller 14X. If the paper sheet rushes in between, the impact may cause a conveyance failure such as an oblique feed, and the preceding document G(1) may not be properly conveyed. The symbols Q1, Q2, Lpass, and Lmin in FIG. 16B will be described later.

Therefore, the present invention is a sheet that can properly convey a preceding sheet even when the succeeding sheet plunges toward the first conveying roller while the preceding sheet is conveyed by the first conveying roller. An object is to provide a feeding device and an image forming apparatus.

As a technique related to the present invention, Patent Document 2 discloses that the diameter of the supply roller (paper feed roller) is made larger than the diameter of the delivery roller (pickup roller) (the diameter of the pickup roller is the diameter of the paper feed roller). However, although the peripheral speeds of the supply roller (paper feed roller) and the delivery roller (pickup roller) are the same (the speed reduction ratio of the pickup roller to the paper feed roller is 2). 1:1 (see the end of paragraph [0065]), which does not disclose the configuration of the present invention.

In order to solve the above problems, the present invention provides a sheet feeding device and an image forming apparatus according to the following first and second aspects.

(1) Sheet Feeding Device According to First Aspect The sheet feeding device according to the first aspect of the present invention calls in a sheet to be stacked by a call-in roller, and the sheet called in by the call-in roller from a first conveying roller. A sheet feeding device that conveys the sheet toward a second conveying roller, wherein the sheet is conveyed between a conveying position where the conveying roller calls in the sheet and a conveying position where the second conveying roller conveys the sheet. When the distance is Lpass and the length of the smallest size of the plurality of sheet sizes in the transport direction is Lmin, the relationship of Lpass>Lmin is satisfied, and the peripheral speed of the intake roller is the first It is characterized in that it is smaller than the peripheral speed of one conveying roller.

(2) Sheet Feeding Device According to Second Aspect In a sheet feeding device according to a second aspect of the present invention, a sheet to be stacked is called by a calling roller, and the sheet called by the calling roller is fed from a first transport roller. A sheet feeding device that conveys a sheet toward a second conveying roller, the sheet conveying device including a first driving unit that rotationally drives the first conveying roller and a second driving unit that rotationally drives the second conveying roller. Drive control is performed on the first drive means of the first transport roller so that the rotation of the first transport roller is stopped after the sheet reaches the second transport roller, and the first transport roller After the stop of the rotation, the sheet conveying timing control for driving and controlling the second driving means of the second conveying roller is performed so that the rotation of the second conveying roller is started.

(3) Image Forming Apparatus An image forming apparatus according to the present invention includes the sheet feeding device of the first aspect or the sheet feeding device of the second aspect.

According to the present invention, it is possible to properly convey the preceding sheet even when the succeeding sheet plunges toward the first conveying roller while the preceding sheet is conveyed by the first conveying roller. ..

FIG. 1 is a schematic cross-sectional view of an image forming apparatus including an image reading device according to the present embodiment as viewed from the front. FIG. 2 is a perspective view showing the sheet feeding device shown in FIG. 1. FIG. 2 is a perspective view showing a state where a part of the exterior cover of the sheet feeding device shown in FIG. 1 is removed and a conveyance system is opened. It is sectional drawing which shows the sheet feeding apparatus shown in FIG. FIG. 2 is a plan view showing a sheet supply unit in the sheet feeding device shown in FIG. 1. FIG. 3 is a bottom view showing a sheet supply unit in the sheet feeding device shown in FIG. 1. FIG. 7 is a perspective view showing a state in which a first holding connecting member and a second holding connecting member of the sheet supply unit shown in FIGS. 5 and 6 are removed. FIG. 5 is a cross-sectional view showing a sheet supply portion of the sheet feeding device shown in FIG. 4. FIG. 3 is a system block diagram showing a schematic configuration of a conveyance control system of the sheet feeding device. FIG. 6 is a state transition diagram showing a document conveying process by the sheet feeding device. FIG. 6 is a state transition diagram showing a document conveying process by the sheet feeding device. FIG. 6 is a state transition diagram showing a document conveying process by the sheet feeding device. FIG. 6 is a plan view showing a conveyance state of a document that is obliquely fed to one side in a direction orthogonal to the sheet conveyance direction. FIG. 7 is a plan view showing a document conveyance state in which the document is obliquely fed to the other side in the direction orthogonal to the sheet conveyance direction. It is a side view which shows the drive transmission mechanism provided with the drive timing pulley and the driven timing pulley. It is a side view which shows the drive transmission mechanism provided with the gear train. 7 is a graph showing the diagonal feed amount of Example 2 together with the diagonal feed amount of Comparative Example. It is a system block diagram which shows schematic structure of the conveyance control system of the sheet feeding apparatus which concerns on 2nd Embodiment. 7 is a timing chart showing a document conveyance control operation in the plain paper mode of the sheet feeding device. 9 is a timing chart showing a document conveyance control operation of the sheet feeding device according to the third embodiment. FIG. 9 is a schematic diagram for explaining a conventional inconvenience that occurs when a sheet is conveyed in a sheet feeding device. FIG. 9 is a schematic diagram for explaining a conventional inconvenience that occurs when a sheet is conveyed in a sheet feeding device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Image forming device]
FIG. 1 is a schematic sectional view of an image forming apparatus 100 including an image reading apparatus 200 according to the present embodiment, as viewed from the front. In the figure, reference numeral X indicates the width direction, reference numeral Y indicates the left-right direction, reference numeral Z indicates the vertical direction (vertical direction), and reference numeral H indicates the conveyance direction of the document G (an example of a sheet).

The image forming apparatus 100 according to the present embodiment is a monochrome image forming apparatus. The image forming apparatus 100 performs an image forming process according to the image data read by the image reading apparatus 200 or the image data transmitted from the outside. The image forming apparatus 100 may be a color image forming apparatus that forms multicolor and monochromatic images on the paper P.

The image forming apparatus 100 includes a document feeding device (sheet feeding device 300) and an image forming device main body 110. The image forming apparatus main body 110 is provided with an image forming unit 102 and a sheet conveying system 103.

The image forming unit 102 includes an exposure unit 1, a developing unit 2, a photosensitive drum 3 acting as an electrostatic latent image carrier, a cleaning unit 4, a charging device 5, and a fixing unit 7. The paper transport system 103 also includes a paper feed tray 81, a manual paper feed tray 82, a discharge roller 31, and a discharge tray 14.

An image reading device 200 for reading the image of the document G is provided above the image forming apparatus main body 110. The image reading apparatus 200 includes an original placing table 221 (specifically, original placing glass) on which the original G is placed, and an original reading plate 222 (specifically, original reading glass). Further, a sheet feeding device 300 is provided above the document placing table 221 and the document reading plate 222. In the image forming apparatus 100, the image of the document G read by the image reading apparatus 200 is sent to the image forming apparatus main body 110 as image data, and the image is recorded on the paper P.

A sheet conveyance path W1 is provided in the image forming apparatus main body 110. The paper feed tray 81 or the manual paper feed tray 82 supplies the paper P to the paper transport path W1. The sheet conveyance path W1 guides the sheet P to the discharge tray 14 via the transfer roller 10 and the fixing unit 7. The fixing unit 7 heats and fixes the toner image formed on the paper P on the paper P. Pickup rollers 11a and 11b, a conveyance roller 12a, a registration roller 13, a transfer roller 10, a heat roller 71, a pressure roller 72, and a discharge roller 31 in the fixing unit 7 are arranged near the sheet conveyance path W1.

In the image forming apparatus 100, the paper P supplied from the paper feed tray 81 or the manual paper feed tray 82 is conveyed to the registration rollers 13. Next, the sheet P is conveyed to the transfer roller 10 by the registration roller 13 at the timing when the sheet P and the toner image on the photosensitive drum 3 are aligned. The toner on the photosensitive drum 3 is transferred onto the paper P by the transfer roller 10. After that, the paper P passes through the heat roller 71 and the pressure roller 72 in the fixing unit 7, passes through the transport roller 12 a and the discharge roller 31, and is discharged onto the discharge tray 14. When image formation is performed not only on the front surface of the paper P but also on the back surface, the paper P is conveyed from the discharge roller 31 to the reverse paper conveyance path W2 in the reverse direction. The sheet P passes through the reversing conveyance rollers 12b to 12b, and the sheet P is turned upside down and guided again to the registration roller 13. Then, the paper P is discharged toward the discharge tray 14 after the toner image is formed and fixed on the back surface in the same manner as the front surface.

[Image reader]
The image reading apparatus 200 includes an image reading unit 400 (specifically, an image reading unit) that scans the original G and reads an image of the original G. The image reading apparatus 200 scans the document G placed on the document placing table 221 while moving the image reading section 400 to one side in the left-right direction Y of the document G along the lower surface of the document placing table 221. In this way, the image reading apparatus 200 reads the image of the document G placed on the document table 221 by the reduction type image sensor 410. Further, the image reading apparatus 200 stops the image reading unit 400 at a position below the document reading plate 222, and allows the document G conveyed by the document feeding device (sheet feeding device 300) to pass through the document reading plate 222. To scan. In this way, the image reading device 200 reads the image of the document G conveyed by the sheet feeding device 300 by the reduction type image sensor 410.

The image reading unit 400 is provided below the document table 221 and the document reading plate 222 so as to be reciprocally movable in the left-right direction Y with respect to the housing 201 of the image reading apparatus 200. The image reading unit 400 is driven by a drive unit (drive motor) not shown.

[Sheet feeding device]
FIG. 2 is a perspective view showing the sheet feeding device 300 shown in FIG. FIG. 3 is a perspective view showing a state where the exterior covers 307 and 308 of a part of the sheet feeding apparatus 300 shown in FIG. 1 are removed and the conveyance system is opened. FIG. 4 is a cross-sectional view showing the sheet feeding device 300 shown in FIG. 5 and 6 are a plan view and a bottom view showing the sheet supply unit 310 in the sheet feeding apparatus 300 shown in FIG. 1, respectively. FIG. 7 is a perspective view showing a state in which the first holding connecting member 314a and the second holding connecting member 314b of the sheet supply unit 310 shown in FIGS. 5 and 6 are removed. FIG. 8 is a cross-sectional view showing a sheet supply unit 310 portion of the sheet feeding device 300 shown in FIG.

The sheet feeding device 300 includes a stacking tray 301, a pair of guide members 302 and 302, a sheet supply unit 310, and a sheet conveying unit 320.

The stack tray 301 stacks a plurality of documents G to G. The pair of guide members 302, 302 regulate the movement of the documents G to G stacked on the stack tray 301 in the width direction X. The guide member 302 is provided so as to be movable (slideable) in the width direction X with respect to the stacking tray 301 so that the document G can be guided according to the size thereof. The guide member 302 reciprocates in the width direction X with reference to the center of the document G in the width direction X.

The sheet supply unit 310 includes a pickup roller 311 (pickup roller), a separation conveyance unit 312, a pair of second conveyance rollers 313, a connection holding member 314, a drive transmission mechanism 315, and a supply drive unit 316 (stepping motor). ) (See FIG. 3) (first drive means) and a conveyance drive unit 317 (stepping motor) (see FIG. 3) (second drive means). The drive transmission mechanism 315 includes a drive timing pulley 315a, a driven timing pulley 315b, and a timing belt 315c.

The call-in roller 311 calls in the highest document G among the plurality of documents G to G stacked on the stacking tray 301. The separation/conveyance unit 312 separates and conveys the originals G that have been read by the intake rollers 311 one by one. The separation conveyance unit 312 includes a first conveyance roller 3121 (paper feed roller) and a separation member [separation roller or separation pad (separation roller 3122 in this example)]. The first transport roller 3121 transports the original G that has been read by the intake roller 311 together with the separation roller 3122 toward the second transport roller 313 one by one. In this example, the second transport roller 313 is a registration roller (a pair of registration rollers), and the operation timing of the downstream member provided on the downstream side of the document G sent from the separation transport unit 312 (the image reading unit 400). The image is conveyed toward the downstream member (the image reading unit 400) at the image reading timing (1).

The second transport roller 313 is rotationally driven independently of the sheet supply unit 310. The second transport roller 313 includes a drive roller 313a that is rotationally driven by the transport drive unit 317, and a driven roller 313b that is in pressure contact with the drive roller 313a (forms a nip). The supply drive unit 316 rotationally drives the first conveyance roller 3121 in the sheet supply unit 310 via the drive transmission mechanism 304 including the connecting gear 303 (see FIGS. 5 and 6) provided on the rotation shaft 3121a. The transport driving unit 317 (see FIG. 3) rotationally drives the second transport roller 313 via a drive transmission mechanism (not shown).

As shown in FIGS. 5 and 6, the connection holding member 314 holds the rotation shaft 311a of the intake roller 311 and the rotation shaft 3121a of the first conveyance roller 3121 rotatably around the axis line at predetermined intervals. It connects so that it may line up in the left-right direction Y. The connection holding member 314 includes a first holding connection member 314a and a second holding connection member 314b. The first holding and connecting member 314a rotatably connects the rotating shaft 311a of the intake roller 311 and the rotating shaft 3121a of the first conveying roller 3121 on one side X1 (front side) in the width direction X. The second holding and connecting member 314b rotatably connects the rotating shaft 311a of the invoking roller 311 and the rotating shaft 3121a of the first conveying roller 3121 on the other side X2 (back side) in the width direction X.

A drive timing pulley 315a having a predetermined number of teeth is provided on the rotary shaft 3121a of the first transport roller 3121. A driven timing pulley 315b having a predetermined number of teeth is provided on the rotary shaft 311a of the intake roller 311. The timing belt 315c is unsupported and is wound around the drive timing pulley 315a and the driven timing pulley 315b. As a result, the rotation shaft 3121a of the first transport roller 3121 is rotationally driven in the forward rotation direction R1 of the sheet transport direction H, and the take-in roller 311 is driven via the drive timing pulley 315a, the timing belt 315c, and the driven timing pulley 315b. The rotating shaft 311a can be rotated in the forward rotation direction R1.

A first one-way clutch 3121b is provided between the first transport roller 3121 and the rotary shaft 3121a. The first one-way clutch 3121b connects the first transport roller 3121 and the rotation shaft 3121a to the rotation of the rotation shaft 3121a in the forward rotation direction R1 and rotates the rotation shaft 3121a in the forward rotation direction R1. 1 The transport roller 3121 is rotated in the forward rotation direction R1. On the other hand, the first one-way clutch 3121b allows the first transport roller 3121 to rotate in the forward rotation direction R1 with respect to the rotation shaft 3121a when the rotation of the rotation shaft 3121a is stopped.

A second one-way clutch 311b is provided between the intake roller 311 and the rotary shaft 311a. The second one-way clutch 311b connects the invoking roller 311 and the rotating shaft 311a with respect to the rotation of the rotating shaft 311a in the forward rotation direction R1 and draws in as the rotating shaft 311a rotates in the forward rotation direction R1. The roller 311 is rotated in the forward rotation direction R1. The second one-way clutch 311b allows the take-in roller 311 to rotate in the forward rotation direction R1 with respect to the rotary shaft 311a when the rotation of the rotary shaft 311a is stopped.

As described above, by using the first one-way clutch 3121b and the second one-way clutch 311b, rotation of the first transport roller 3121 to the rotation shaft 3121a after the leading edge of the document G reaches the second transport roller 313 (roller nip position). Even if the driving is stopped, both the first transport roller 3121 and the intake roller 311 can be rotated in the forward rotation direction R1.

A torque limiter 3121c is provided between the first holding and connecting member 314a and the rotating shaft 3121a. The torque limiter 3121c restricts rotation of the first holding connecting member 314a with respect to the rotating shaft 3121a when the first holding connecting member 314a has a predetermined load or less with respect to the rotation of the rotating shaft 3121a. On the other hand, when the first holding connecting member 314a exceeds a predetermined load with respect to the rotation of the rotating shaft 3121a, the rotation of the first holding connecting member 314a with respect to the rotating shaft 3121a is allowed. As a result, when the first holding connecting member 314a has a predetermined load or less with respect to the rotation of the rotating shaft 3121a, the first holding connecting member 314a is swung to rotate the forward rotation direction R1 and lower the intake roller 311. By rotating in the reverse rotation direction R2, the intake roller 311 can be raised. When the first holding connecting member 314a exceeds a predetermined load with respect to the rotation of the rotating shaft 3121a, the rotating shaft 3121a can be rotated with respect to the first holding connecting member 314a. Accordingly, when the rotary shaft 3121a rotates in the forward rotation direction R1, the intake roller 311 is stacked on the stack tray 301 by the rotation of the intake roller 311 about the rotary shaft 3121a in the normal rotation direction R1. It is possible to press from a plurality of originals G to G. Further, when the rotary shaft 311a rotates in the normal rotation direction R1 along with the rotation of the rotary shaft 3121a in the normal rotation direction R1, the uppermost original G is moved in the sheet conveyance direction H by the rotation of the take-in roller 311 in the normal rotation direction R1. Can be sent to.

The separation roller 3122 is arranged so as to face the first transport roller 3121. A torque limiter 3122b (see FIG. 8) is provided between the separation roller 3122 and the rotating shaft 3122a. The torque limiter 3122b restricts the rotation of the separation roller 3122 with respect to the rotation shaft 3122a when the separation roller 3122 has a predetermined load or less with respect to the rotation of the rotation shaft 3122a. On the other hand, when the separation roller 3122 exceeds a predetermined load with respect to the rotation of the rotation shaft 3122a, the separation roller 3122 is allowed to rotate with respect to the rotation shaft 3122a. As a result, the conveyance of the second and subsequent originals G of the plurality of originals G 1 to G stacked on the stacking tray 301 in the sheet conveyance direction H is restricted, and the lowermost (final original G) sheet is conveyed. Transport in the transport direction H can be permitted.

FIG. 9 is a system block diagram showing a schematic configuration of the transport control system of the sheet feeding apparatus 300.

As shown in FIG. 9, the sheet feeding device 300 includes a control unit 330. The control unit 330 includes a processing unit 331 including a microcomputer such as a CPU (Central Processing Unit), and a storage unit 332 including a nonvolatile memory such as a ROM and a volatile memory such as a RAM. The control unit 330 controls the operation of various components by the processing unit 331 loading the control program stored in the ROM of the storage unit 332 in advance on the RAM of the storage unit 332 and executing the control program. As a result, the control unit 330 can perform sheet conveyance control.

The sheet feeding device 300 further includes a sheet presence/absence detection unit 305 (see FIG. 3) and a sheet timing detection unit 306 (see FIGS. 3, 4, and 8). The sheet presence/absence detection unit 305 detects whether or not the document G is placed on the stacking tray 301. The sheet presence/absence detection unit 305 is electrically connected to the input system of the control unit 330. Thereby, the control unit 330 can detect (recognize) whether or not the document G is placed on the stacking tray 301. The sheet timing detection unit 306 detects a passage timing at which the leading edge of the document G sent from the first transport roller 3121 passes a predetermined position on the upstream side of the second transport roller 313 (roller nip position). The seat timing detection unit 306 is electrically connected to the input system of the control unit 330. Accordingly, the control unit 330 can detect (recognize) the passage timing until the leading edge of the document G sent from the first transport roller 3121 reaches the second transport roller 313 (roller nip position). The supply drive unit 316 and the transport drive unit 317 are electrically connected to the output system of the control unit 330. As a result, the control unit 330 can control the operation of the supply driving unit 316 to drive the first transport roller 3121 to rotate, and the driven roller 311 to rotate following the rotation of the first transport roller 3121. In addition, the control unit 330 can control the operation of the transport driving unit 317 to rotationally drive the second transport roller 313.

When the sheet presence/absence detection unit 305 detects that the document G is placed on the stacking tray 301 and an instruction to send the document G is issued, the control unit 330 rotationally drives the supply driving unit 316. In addition, the control unit 330 passes the sheet timing detection unit 306 at a passage timing at which the leading edge of the document G sent from the first transport roller 3121 passes a predetermined position upstream of the second transport roller 313 (roller nip position). The transport driving unit 317 is rotationally driven on the basis of.

(Sheet feeding operation of the sheet feeding device)
10A to 10C are state transition diagrams showing a process of conveying the document G by the sheet feeding device 300.

In the sheet feeding apparatus 300, as shown in FIG. 10A, a call-in position Q1 in which the call-in roller 311 calls in the document G (a position in which the call-in roller 311 contacts the document G) and a second feeding roller 313 feeds the document G. The transport distance of the document G between the transport position Q2 (the nip position between the driving roller 313a and the driven roller 313b in the second transport roller 313) is set to Lpass, and the minimum size (in this example, the sheet size) of a plurality of sheet sizes is used. When the length of the original G (name card size) (name card in this example) in the sheet conveying direction H is Lmin, the relationship of Lpass>Lmin is satisfied.

The sheet feeding device 300 calls in the loaded originals G to G by the call-in roller 311, and transfers the original G called in by the call-in roller 311 from the first transport roller 3121 (paper feed roller) to the second transport roller 313 (this In the example, they are conveyed one by one toward the registration roller). Here, during the conveyance operation of continuously conveying the plurality of originals G to G, the call-in roller 311 remains lowered (while being in contact with the uppermost original G), and the preceding highest original G. Even after (1) is called in, it rotates in the forward rotation direction R1 of the sheet conveying direction H, and immediately follows the next highest document G(2).

Then, while the preceding original G(1) is being conveyed by the first conveying rollers 3121, the succeeding original G(2) is projected toward the first conveying rollers 3121.

11A and 11B are plan views showing the conveyance state of the document G which is obliquely fed to one side and the other side in the direction orthogonal to the sheet conveyance direction H, respectively. 11A and 11B, the broken line indicates a state in which the skew feed amount |±m| of the document G is 0 (state in which skew feed is not performed). The diagonal feed amount on one side is (+m), and the diagonal feed amount on the other side is (-m).

In the conventional sheet feeding device 10X, as shown in FIG. 16B, a conveyance error such as oblique feeding may occur due to the impact, and the preceding document G(1) may not be conveyed properly. This means that the transport distance of the document G between the call-in position Q1 at which the call-in roller 11X calls in the document G and the transport position Q2 (roller nip position) at which the second transport roller 13X transports the document G is Lpass. When the length of the document G (for example, a business card) of the minimum size (for example, a business card size) of the plurality of sheet sizes in the sheet conveying direction H is Lmin, it becomes remarkable when the relationship of Lpass>Lmin is satisfied. In this case, for example, even if the trailing edge of the preceding document G(1) is separated from the ingesting roller 11X, the leading edge of the preceding document G(1) has not reached the second transport roller 13X, so the preceding document G (1) is conveyed by the first conveying roller 12X (at one position in the sheet conveying direction H). Then, the preceding original G(1) is likely to be obliquely conveyed due to the impact when the succeeding original G(2) plunges toward the first conveying roller 12X, and further, the preceding original G(1) is 2 The absolute value of the skew feed amount ±m (FIGS. 11A and 11B) which is the difference in the feed amount between the one end and the other end of the leading edge of the preceding document G(1) in the sheet conveyance direction H as it moves toward the conveyance roller 13X. ±m| tends to be large. Therefore, when the succeeding original G(2) plunges toward the first transport roller 12X, the farther the preceding original G(1) is from the second transport roller 13X, the more skewed the preceding original G(1) is. The feed amount |±m| becomes large.

(First embodiment)
In this respect, the sheet feeding apparatus 300(1) according to the first embodiment is configured such that the peripheral speed V1 of the ingesting roller 311 is smaller than the peripheral speed V2 of the first conveying roller 3121 in the sheet supply unit 310. (V1<V2). In addition, the numeral in the parentheses of the reference numeral 300 indicates the number of the embodiment, and the reference numeral 300 without the subscript means the configuration common to the first embodiment and the second to fourth embodiments described later. doing.

By doing so, the succeeding original G(2) can be delayed with respect to the preceding original G(1), and accordingly, when the succeeding original G(2) enters the first conveying roller 3121. , The leading edge of the preceding document G(1) can be brought close to the second transport roller 313. This makes it possible to reduce the skew feed amount |±m| of the preceding document G(1). As the peripheral velocity V1 of the ingesting roller 311 which is lower than the peripheral velocity V2 of the first conveying roller 3121, when the leading edge of the preceding document G(1) reaches the second conveying roller 313 (roller nip position), the following document is A peripheral speed at which G(2) reaches the first transport roller 3121 or higher or higher than the peripheral speed can be exemplified.

Here, when the preceding original G(1) is conveyed by the first conveying roller 3121 and the succeeding original G(2) is conveyed by the taking-in roller 311, the peripheral speed V1 of the taking-in roller 311 is the first. It is lower than the peripheral speed V2 of the transport roller 3121. However, when one original G is conveyed by both the first conveying roller 3121 and the taking-in roller 311, the peripheral speed V1 of the taking-in roller 311 is the first speed when the taking-in roller 311 idles by the second one-way clutch 311b. The speed is the same as the peripheral speed V2 of the transport roller 3121.

Further, in the sheet feeding device 300(1) according to the first embodiment, the type of the document G includes a business card. The minimum size is a business card size. By the way, since the business card is thicker than the plain paper, it is difficult to secure the skew feed amount |±m| by the second transport roller 313 (registration roller), and it is difficult to correct the skew feed. In this respect, in the first embodiment, even if a business card in which it is difficult to correct the diagonal feed by the second transport roller 313 (registration roller) is used as the original G, the diagonal feed amount |±m| The size can be reduced and the business card can be properly transported.

The following mode can be exemplified as a mode in which the peripheral speed V1 of the take-in roller 311 is made lower than the peripheral speed V2 of the first transport roller 3121.
(A) The number of teeth of the driven timing pulley 315b of the intake roller 311 and the number of teeth of the drive timing pulley 315a of the first conveyor roller 3121 are set to be the same, and the diameter φb of the intake roller 311 of the first conveyor roller 3121 is set to the first value. A mode in which the diameter is smaller than the diameter φa of the transport roller 3121.
(B) The number of teeth of the driven timing pulley 315b of the ingesting roller 311 is made larger than the number of teeth of the drive timing pulley 315a of the first conveying roller 3121, and the diameter φb of the inducing roller 311 of the first conveying roller 3121 and the first A mode in which the diameter φa of the transport roller 3121 is the same.
(C) The number of teeth of the driven timing pulley 315b of the intake roller 311 is made larger than the number of teeth of the drive timing pulley 315a of the first conveyor roller 3121, and the diameter φb of the intake roller 311 of the first conveyor roller 3121 is set to the first value. A mode in which the diameter is smaller than the diameter φa of the transport roller 3121.

The sheet feeding device 300(1) according to the first embodiment includes a drive transmission mechanism 315 that transmits the rotational driving force from the first transport roller 3121 to the intake roller 311. The diameter φb (see FIG. 10B) of the intake roller 311 is smaller than the diameter φa (see FIG. 10B) of the first transport roller 3121. By doing so, the peripheral speed V1 of the intake roller 311 can be made smaller than the peripheral speed V2 of the first transport roller 3121 with a simple configuration.

FIG. 12A is a side view showing a drive transmission mechanism 315 including a drive timing pulley 315a and a driven timing pulley 315b.

In the sheet feeding device 300(1) according to the first embodiment, the drive transmission mechanism 315 transmits the drive from the first transport roller 3121 to the take-in roller 311.

As shown in FIG. 12A, the drive transmission mechanism 315 includes a drive timing pulley 315a, a driven timing pulley 315b, and a timing belt 315c. The number of teeth of the drive timing pulley 315a is Z1 (18 teeth), and the number of teeth of the driven timing pulley 315b is Z2 (22 teeth) (>Z1). Therefore, the reduction ratio (Z1/Z2) of the first transport roller 3121 (the number of teeth Z1) to the intake roller 311 (the number of teeth Z2) is a value smaller than 1 (18/22=0.82... ). ..

FIG. 12B is a side view showing the drive transmission mechanism 318 including the gear train 318c.

A drive transmission mechanism 318 including a gear train 318c may be used instead of the drive transmission mechanism 315 including the drive timing pulley 315a and the driven timing pulley 315b.

As shown in FIG. 12B, the drive transmission mechanism 318 includes a drive gear 318a, a driven gear 318b, and a gear train 318c having an odd number of intermediate gears (318c1 to 318c3). The drive gear 318a is provided on the rotary shaft 3121a of the first transport roller 3121, and the driven gear 318b is provided on the rotary shaft 311a of the take-in roller 311. The gear train 318c is composed of three intermediate gears 318c1 to 318c3. The intermediate gear 318c1 meshes with the drive gear 318a. The intermediate gear 318c3 meshes with the driven gear 318b. The intermediate gear 318c3 meshes with both the intermediate gear 318c1 and the intermediate gear 318c3. The number of teeth of the drive gear 318a is Z1 (18 teeth), and the number of teeth of the driven gear 318b is Z2 (22 teeth). Therefore, the reduction ratio (Z1/Z2) of the first transport roller 3121 (the number of teeth Z1) to the intake roller 311 (the number of teeth Z2) is a value smaller than 1 (18/22=0.82... ). .. Since the reduction ratio of the drive transmission mechanism 318 does not depend on the number of teeth of the gear train 318c, the number of teeth of the gear train 318c can be set appropriately.

Next, as Examples 1 and 2, since the skew feeding amount was examined in the sheet feeding device 300(1) according to the first embodiment, it will be described below together with a comparative example in which the skew feeding amount was examined with the conventional configuration.

In Examples 1 and 2, and the comparative example, the transport distance between the call-in position Q1 and the transport position Q3 (see FIG. 10A) at which the first transport roller 3121 transports the document G is 47.6 mm, and the transport position Q3 and the transport position Q2. And Lpass is 120.5 mm (47.6 mm+72.9 mm), the diameter φa of the first transport roller 3121 is 22 mm, the number of teeth of the drive timing pulley 315a is 18, and the first transport roller 3121 is The peripheral speed V2 of was set to 500 mm/s.

In Examples 1 and 2, and the comparative example, the diameter φb of the intake roller 311 is 20 mm, 20 mm, and 22 mm, and the number of teeth of the driven timing pulley 315b is 18 teeth, 22 teeth, 18 teeth, and the intake roller 311. The peripheral speed V1 is set to 454.5 mm/s, 371.9 mm/s, and 500 mm/s, and 65 business cards (length 91 mm in the sheet conveyance direction H) are stacked on the stacking tray 301 as the document G and the number of passed sheets T The oblique feed rate W [=(S/T)×100%], which is the ratio of the obliquely fed sheet number S, was examined. As a result, the oblique feed rate W was improved by 15.4% (Example 1: 25.5%-Comparative example: 10.1%) in Example 1 and 43.3% in Example 2 as compared with Comparative Example. (Example 2: 53.4%-Comparative example: 10.1%). In addition, the first copy time, which is the time from the start of printing the first sheet P to the ejection of the first sheet P, was hardly delayed as compared with the comparative example.

FIG. 13 is a graph showing the skew feed amount ±m of Example 2 together with the skew feed amount ±m of the comparative example. In FIG. 13, the vertical axis represents the skew feed amount ±m [mm], and the horizontal axis represents the number of sheets of paper on which 50 business cards are stacked on the stacking tray 301.

As shown in FIG. 13, in Example 1, it was found that the oblique feed amount |±m| can be made smaller than in the comparative example, and a business card of a business card size (for example, 91 mm×55 mm) can be stably passed.

(Second embodiment)
FIG. 14 is a system block diagram showing a schematic configuration of the conveyance control system of the sheet feeding apparatus 300(2) according to the second embodiment.

As shown in FIG. 14, the sheet feeding apparatus 300(2) according to the second embodiment rotationally drives the first driving unit 319a (stepping motor) that rotationally drives the intake roller 311 and the first transport roller 3121. And a second driving unit 319b (stepping motor) that applies force. The first drive unit 319a and the second drive unit 319b form a supply drive unit 319.

The first drive unit 319a and the second drive unit 319b are electrically connected to the output system of the control unit 330. Accordingly, the controller 330 can independently control the operation of the first driver 319a and the second driver 319b. The control unit 330 determines whether the reduction ratio of the drive transmission mechanisms 315 and 318 is smaller than or equal to 1 regardless of whether the diameter φa of the first transport roller 3121 is larger than or equal to the diameter φb of the intake roller 311. Regardless, when the preceding document G(1) is sent by the ingesting roller 311, the first drive is performed so that the peripheral speed V1 of the injecting roller 311 and the peripheral speed V2 of the first conveying roller 3121 are the same or substantially the same. The operation of the unit 319a and the second driving unit 319b is controlled. When the feeding of the preceding document G(1) by the call-in roller 311 is completed, the control unit 330 performs the first drive so that the peripheral speed V1 of the call-in roller 311 becomes lower than the peripheral speed V2 of the first transport roller 3121. The operation of the unit 319a and the second driving unit 319b is controlled. At this time, the control unit 330 may maintain the peripheral speed V2 of the first conveying roller 3121 and set the peripheral speed V1 of the invoking roller 311 to be lower than the peripheral speed V2 of the first conveying roller 3121, or The peripheral speed V2 of the conveying roller 3121 may be made higher than the peripheral speed V1 of the intake roller 311 while maintaining the peripheral speed V1 of the intake roller 311. Further, the control unit 330 sets the peripheral speed V2 of the first conveying roller 3121 to be higher than the peripheral speed V1 of the taking-in roller 311 while the peripheral speed V1 of the taking-in roller 311 is larger than the peripheral speed V2 of the first conveying roller 3121. May be smaller. Then, when the leading edge of the preceding document G(1) reaches the second conveying roller 313 (roller nip position), the control unit 330 determines the peripheral speed V1 of the take-in roller 311 and the peripheral speed V2 of the first conveying roller 3121. The first drive unit 319a and the second drive unit 319b are operated and controlled so as to return to the peripheral speed of (the same or substantially the same).

By doing so, from the end of the feeding of the preceding document G(1) by the invocation roller 311 to the arrival of the leading edge of the preceding document G(1) at the second transport roller 313 (roller nip position). The peripheral speed V1 of the take-in roller 311 is made smaller than the peripheral speed V2 of the first conveying roller 3121 for a period required to make the peripheral speed V1 of the taking-in roller 311 smaller than the peripheral speed V2 of the first conveying roller 3121. be able to.

(Third Embodiment)
(Sheet feeding operation of the sheet feeding device)
FIG. 15A is a timing chart showing the transport control operation of the document G in the plain paper mode of the sheet feeding device. FIG. 15B is a timing chart showing the document G conveyance control operation of the sheet feeding apparatus 300(3) according to the third embodiment. In FIGS. 15A and 15B, “α” represents the timing when the leading edge of the preceding document G(1) reaches the second transport roller 313 (roller nip position). Further, “β” indicates the detection timing of the document G by the sheet timing detection unit 306. The conveyance control of the document G is performed based on the detection timing of the document G by the sheet timing detection unit 306.

By the way, in the sheet feeding device, regardless of the relation of Lpass>Lmin, and whether the peripheral speed of the ingesting roller 311 is smaller than or equal to the peripheral speed of the first conveying roller 3121, the plurality of originals G to G are formed. 15A, the preceding original document G(1) reaches the stopped second conveying roller 313 (roller nip position) (see “α”) and the preceding original G(1) is conveyed first as shown in FIG. 15A. The first transport roller 3121 rotates in the forward rotation direction R1 of the sheet transport direction H without stopping while bending the front end of the document G(1) (while securing the registration amount). Then, while the first transport roller 3121 rotates, the rotation of the second transport roller 313 starts at a predetermined timing (see “δ”). Then, a load is applied to the preceding document G(1), and it is not possible to stably and reliably secure the amount of deflection (resist amount) of the leading end of the preceding document G(1). Therefore, the degree of correction of the diagonal feed amount |±m| by the second transport roller 313 (registration roller) is reduced.

In this respect, in the sheet feeding apparatus 300(3) according to the third embodiment, as shown in FIG. 15B, the leading end of the conveyed document G [preceding document G(1)] is the second conveyance roller 313 (roller nip position). ) Is reached, drive control (stop control by a pulse signal) is performed on the supply drive units 316 and 319 of the first transport roller 3121 so that the rotation of the first transport roller 3121 is stopped (see “ε”), and , So that the rotation of the second transport roller 313 starts after the rotation of the first transport roller 3121 is stopped (see “δ”). Drive control is performed on the transport drive unit 317 of the second transport roller 313 (start control by a pulse signal). The sheet conveyance timing control is performed.

By doing so, the leading edge of the preceding original G(1) reaches the stopped second conveying roller 313 (roller nip position) during the conveying operation of continuously conveying the plurality of originals G to G, and the preceding original G(1) is conveyed. After the front end of the document G(1) is bent (registration amount is secured), the rotation of the first transport roller 3121 is stopped, and the second transport roller 3121 is stopped at the predetermined timing while the rotation of the first transport roller 3121 is stopped. The rotation of the transport roller 313 can be started. As a result, the load on the preceding document G(1) can be reduced, and thus the amount of deflection (resist amount) at the leading edge of the preceding document G(1) can be stably and reliably ensured. .. Therefore, the degree of correction of the diagonal feed amount |±m| by the second transport roller 313 (registration roller) can be improved.

By the way, in the sheet transport timing control according to the third embodiment, the rotation of the second transport roller 313 may be started (see “δ”) when the rotation of the first transport roller 3121 is stopped (see “γ”). Although preferable, an error may occur in the transport timing of the preceding document G(1) due to factors such as variations in detection by the sheet timing detection unit 306 and variations in transport of the original G. Therefore, by design, even if the rotation of the second transport roller 313 is started when the rotation of the first transport roller 3121 is stopped, the second transport roller 3121 is rotated before the rotation of the first transport roller 3121 is stopped. The rotation of 313 may start.

In this regard, as shown in FIG. 15B, the sheet conveyance timing control according to the third embodiment is performed after a predetermined time td (for example, 100 ms) has elapsed after the rotation of the first conveyance roller 3121 is stopped (see “γ”). The transport control unit 317 of the second transport roller 313 is drive-controlled (start control by a pulse signal) so that the rotation of the second transport roller 313 starts. By doing so, even if an error occurs in the conveyance timing of the preceding document G(1) due to factors such as detection variations of the sheet timing detection unit 306 and conveyance variations of the document G, after the rotation of the first conveyance roller 3121 is stopped. Therefore, the rotation of the second transport roller 313 can be surely started.

In the sheet conveyance timing control according to the third embodiment, as shown in FIG. 15B, drive control is performed on the supply drive units 316 and 319 of the first conveyance roller 3121 so that the rotation of the first conveyance roller 3121 is decelerated. (Deceleration control based on a pulse signal) (see “ε”) is performed with respect to the supply driving units 316 and 319 of the first conveyance roller 3121 so that the first conveyance roller 3121 stops after the first conveyance roller 3121 decelerates. The leading end of the document G reaches the second transport roller 313 (roller nip position) until the first transport roller 3121 stops by drive control (stop control by pulse signal) (see “γ”) (“ (See α)) The supply drive units 316 and 319 of the first transport roller 3121 are drive-controlled (stop control by a pulse signal). By doing so, the rotation of the second transport roller 313 can be started as early as possible, and the number of image forming sheets per unit time can be improved.

(Fourth Embodiment)
By the way, in the sheet transport timing control, the rotation of the second transport roller 313 is started after the rotation of the first transport roller 3121 is stopped, so that there is a concern that the number of image formation sheets per unit time may decrease. Further, the types of sheets include plain paper and business cards, and since plain paper is thinner than business cards, it is easy to secure the skew feed amount |±m| by the second transport roller 313 (registration roller) and correct the skew feed. Easy to do.

In this respect, the sheet feeding device 300(4) according to the fourth embodiment is capable of switching between a plain paper mode for carrying plain paper and a business card mode for carrying business cards. When the mode is switched to the business card mode, the sheet conveyance timing control according to the third embodiment is performed. In this example, the plain paper mode performs the sheet transport timing control shown in FIG. 15A, and the business card mode performs the sheet transport timing control shown in FIG. 15B.

By doing so, the third embodiment is used only when a business card in which it is difficult to correct the oblique feeding by the second transport roller 313 (registration roller) as the original G from the plain paper mode in which the number of images formed per unit time is a predetermined number. It is possible to switch to the business card mode in which the sheet conveyance timing control according to the above is performed, and thus it is possible to secure the number of image formation sheets per unit time in the plain paper mode.

(Other embodiments)
A combination of the sheet feeding devices 300(1), 300(2) according to the first embodiment and the second embodiment and the sheet feeding devices 300(3), 300(4) according to the third embodiment and the fourth embodiment. May be.

That is, the sheet feeding timing control according to the third embodiment or the fourth embodiment may be performed in the sheet feeding devices 300(1) and 300(2) according to the first embodiment and the second embodiment.

Further, in the first to fourth embodiments, the sheet is the original G and the conveyance control of the original G stacked on the stacking tray 301 is performed. However, the sheet is the paper P, and the paper feed tray 81 or the manual feed is used. The conveyance control of the sheets P stacked on the sheet feed tray 82 may be performed.

The present invention is not limited to the embodiments described above, and can be implemented in various other forms. Therefore, the embodiment is merely an example in all respects and should not be limitedly interpreted. The scope of the present invention is defined by the scope of the claims, and is not bound by the text of the specification. Furthermore, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

100 image forming apparatus 200 image reading apparatus 221 original placing table 222 original reading plate 300 sheet feeding apparatus 301 stacking tray 302 guide member 303 connecting gear 304 drive transmission mechanism 305 sheet presence detecting section 306 sheet timing detecting section 307 exterior cover 310 sheet supplying section 311 Call-in roller 312 Separation/conveyance section 3121 First conveyance roller 3122 Separation roller 313 Second conveyance roller 314 Connection/holding member 315 Drive transmission mechanism 316 Supply drive section 317 Conveyance drive section 318 Drive transmission mechanism 319 Supply drive section 319a First drive section 319b 2nd drive part 320 Sheet conveyance part 330 Control part 331 Processing part 332 Storage part 400 Image reading part 81 Paper feed tray 82 Paper feed tray G Document H Sheet conveyance direction P Paper Q1 Calling position Q2 Conveying position Q3 Conveying position R1 Correct Rotation direction R2 Reverse rotation direction X Width direction Y Left-right direction Z Up-down direction td Predetermined time φa Diameter φb Diameter

Claims (10)

A sheet feeding device that calls in a stacked sheet by a call-in roller and conveys the sheet called in by the call-in roller from a first conveyance roller toward a second conveyance roller,
The transport distance of the sheet between the call-in position at which the call-in roller calls in the sheet and the transport position at which the second transport roller transports the sheet is Lpass, and is a minimum size of a plurality of types of sheet sizes. When the length of the sheet in the conveying direction is Lmin, the relationship of Lpass>Lmin is satisfied, and the peripheral speed of the invoking roller is smaller than the peripheral speed of the first conveying roller. apparatus. The sheet feeding device according to claim 1,
The sheet feeding device, wherein the sheet type includes a business card, and the minimum size is a business card size. The sheet feeding device according to claim 1 or 2, wherein
A drive transmission mechanism for transmitting the rotational drive force from the first transport roller to the intake roller,
The sheet feeding device, wherein the diameter of the intake roller is smaller than the diameter of the first transport roller. The sheet feeding device according to any one of claims 1 to 3,
A drive transmission mechanism for transmitting the rotational drive force from the first transport roller to the intake roller,
A sheet feeding device, wherein a speed reduction ratio of the first transport roller to the intake roller in the drive transmission mechanism is smaller than 1. The sheet feeding device according to any one of claims 1 to 4,
A first drive unit that rotationally drives the first transport roller; and a second drive unit that rotationally drives the second transport roller,
The first drive unit of the first transport roller is drive-controlled so that the rotation of the first transport roller is stopped after the transported sheet reaches the second transport roller, and A sheet feeding timing control for driving and controlling the second driving means of the second feeding roller so that the rotation of the second feeding roller starts after the rotation of the feeding roller is stopped. .. A sheet feeding device that calls in a stacked sheet by a call-in roller and conveys the sheet called in by the call-in roller from a first conveyance roller toward a second conveyance roller,
A first drive unit that rotationally drives the first transport roller; and a second drive unit that rotationally drives the second transport roller,
The first drive unit of the first transport roller is drive-controlled so that the rotation of the first transport roller is stopped after the transported sheet reaches the second transport roller, and A sheet feeding timing control for driving and controlling the second driving means of the second feeding roller so that the rotation of the second feeding roller starts after the rotation of the feeding roller is stopped. .. The sheet feeding device according to claim 6,
In the sheet transport timing control, the second drive means of the second transport roller is driven so that the rotation of the second transport roller starts after a lapse of a predetermined time after the rotation of the first transport roller is stopped. A sheet feeding device that is controlled. The sheet feeding device according to claim 6 or 7,
In the sheet transport timing control, the first transport roller is controlled to be decelerated so that the rotation of the first transport roller is decelerated, and the first transport roller is decelerated before the first transport roller is decelerated. The sheet is allowed to reach the second transport roller before the first transport roller is stopped by controlling the driving of the first transport roller to stop the transport roller. A sheet feeding device, which controls driving of the first driving unit of the first conveying roller. The sheet feeding device according to any one of claims 6 to 8,
The types of sheets include plain paper and business cards,
It is possible to switch between a plain paper mode for carrying the plain paper and a business card mode for carrying the business card,
A sheet feeding device, wherein the sheet conveyance timing control is performed when switching to the business card mode. An image forming apparatus comprising the sheet feeding device according to any one of claims 1 to 9.

Images