JP2023058746A - Sheet feeding apparatus, image reading apparatus, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably feed various sheets and contribute to productivity improvement.

SOLUTION: A sheet detection position by second detection means is located more outside in the width direction than a sheet detection position by first detection means and is different in a position in the feeding direction. Control means changes a mode of feeding operation based on information on the length in the width direction of a sheet acquired by size acquiring means. In a first mode, after starting to feed a preceding sheet, when at least one of the first detection means and the second detection means changes from a detection state to a non-detection state, feeding of a subsequent sheet is started. In a second mode, after starting to feed the preceding sheet, regardless of detection result of the second detection means, when the first detection means changes from the detection state to the non-detection state, feeding of the subsequent sheet is started. The first mode is executed when a sheet of a first size is fed. The second mode is executed when a sheet of a second size having a shorter length in the width direction than the sheet of the first size is fed.

SELECTED DRAWING: Figure 5

COPYRIGHT: (C)2023,JPO&INPIT

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device that feeds sheets, and an image reading device and an image forming device that include the sheet feeding device.

A sheet feeding apparatus used in an image reading apparatus or an image forming apparatus is required to increase the number of sheets fed per unit time, thereby contributing to improvement in productivity of the entire apparatus. For example, in the case of a document feeder for feeding documents in an image forming apparatus equipped with a scanner function such as a copier or a multifunction machine, it is possible to read image information from multiple documents in a short time. Documents are required to be fed at intervals as short as possible.

In Patent Document 1, a first sensor provided downstream from a separation nip that separates documents and a second sensor provided upstream from the separation nip are used to determine the feeding timing of the next document. A document feeder is described. According to this document, when one of the two sensors changes from detecting the document to not detecting the document, it is determined that feeding of the next document can be started.

JP 2010-202359 A

By the way, regarding the sheet feeding device, not only the improvement of productivity but also the stable feeding of various sheets of different sizes are required. However, when a plurality of sensors for detecting sheets are provided, the detection positions of the sensors in the width direction may not be aligned for various reasons such as avoiding interference with other members. In such a case, when sheet feeding is controlled by combining the detection results of a plurality of sensors as in the document feeder described in Japanese Patent Application Laid-Open No. 2002-200313, the behavior of some sensors may change depending on the sheet size. In some cases, the feeding operation became unstable.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a sheet feeding device capable of stably feeding various sheets and improving productivity, as well as an image reading apparatus and an image forming apparatus having the sheet feeding device. do.

According to one aspect of the present invention, a sheet stacking unit on which sheets are stacked, a sheet feeding unit that feeds sheets from the sheet stacking unit in a feeding direction, and a sheet that is fed by the sheet feeding unit is fed by the sheet stacking unit. a first detection means for detecting at one detection position; and a second detection position outside the first detection position in the width direction perpendicular to the feeding direction and different from the first detection position in the feeding direction. second detection means for detecting a sheet; size acquisition means for acquiring information about the length of the sheet stacked on the sheet stacking portion in the width direction; and sheet feeding based on the information acquired by the size acquisition means. and a control means for controlling the feeding means, wherein the control means controls whether at least one of the first detection means and the second detection means detects the sheet after the sheet feeding means starts feeding the preceding sheet. A first mode in which feeding of the succeeding sheet is started when the state of detecting the sheet changes to a state of not detecting the sheet; a second mode in which feeding of the succeeding sheet is started when the state in which the first detection means detects the sheet changes to the state in which the first detection means does not detect the sheet, regardless of the detection result of the detection means; Any one of a plurality of modes can be executed, and the first mode is executed when feeding a sheet of a first size, and a sheet of a second size whose length in the width direction is shorter than that of the first size sheet is fed. The sheet feeding apparatus is characterized in that the second mode is executed when feeding the sheet.

According to the present invention, various sheets can be stably fed, and productivity can be improved.

1 is a schematic diagram of an image forming apparatus according to an embodiment of the present disclosure; FIG. 1A is a schematic diagram of an image reading apparatus according to the present embodiment, and FIG. 1B is a block diagram showing its control configuration; FIG. 1A and 1B are views of a part of the image reading apparatus according to the present embodiment as viewed from the width direction; FIG. 6A to 6F are schematic diagrams showing the relationship between the detection result of the document sensor and the position of the document according to the embodiment; 4 is a flow chart showing a control method for document feeding operation according to the present embodiment.

Preferred embodiments for carrying out the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an image forming apparatus 1 of this embodiment in which an image reading device 1S is attached to the upper portion of an apparatus main body 2. As shown in FIG. The image reading device 1S reads image information from the document D and transfers it to the control board of the device main body 2 . The device main body 2 forms an image on the recording material S based on image information received from the image reading device 1S and image information received from an external computer connected via a network. Sheets used as the document D or the recording material S include paper such as plain paper and thick paper, plastic films such as overhead projector sheets, special-shaped sheets such as envelopes and index paper, and cloth.

First, the overall configuration of the image forming apparatus 1 will be described. As shown in FIG. 1, an apparatus main body 2 of an image forming apparatus 1 is equipped with an electrophotographic image forming section 3 . The image forming section 3 of this embodiment has a configuration of a tandem type intermediate transfer system, and includes four image forming units 10Y, 10M, 10C, and 10K, and an intermediate transfer belt 23 as an intermediate transfer member.

The image forming unit 10Y forms a yellow toner image by an electrophotographic process. That is, the photosensitive drum 11, which is a photosensitive member, rotates, and the charging device 12 uniformly charges the surface of the drum. The laser scanner 13 irradiates the photosensitive drum 11 with laser light modulated based on image information to write an electrostatic latent image on the surface of the drum. The developing device 14 supplies charged toner particles to the photosensitive drum 11 to develop the electrostatic latent image on the surface of the drum into a toner image. This toner image is primarily transferred onto the intermediate transfer belt 23 by the primary transfer roller 15 . A drum cleaner 16 removes deposits such as transfer residual toner remaining on the photosensitive drum 11 without being transferred to the intermediate transfer belt 23 . The above processes are carried out in parallel in the image forming units 10Y to 10K to form toner images of yellow, magenta, cyan, and black colors.

The intermediate transfer belt 23 is wound around a plurality of rollers including the inner secondary transfer roller 18, and is rotationally driven in a direction along the rotation direction of the photosensitive drum 11 (clockwise direction in the drawing). The toner images of respective colors formed in the image forming units 10Y to 10K are primarily transferred so as to overlap each other, and a full-color toner image is formed on the intermediate transfer belt 23. FIG. This toner image is conveyed to the secondary transfer portion formed between the secondary transfer inner roller 18 and the opposing secondary transfer roller 19 by the rotation of the intermediate transfer belt 23 .

The image forming apparatus 1 includes a cassette feeding portion 4 and a manual feeding portion 5 as a sheet feeding device for feeding the recording material S. As shown in FIG. The cassette feeding unit 4 has a plurality of sheet storage containers 6 , and the recording material S is fed one by one from any one of the sheet storage containers 6 toward the registration roller 17 by the feeding unit 7 . A manual feeding unit 5 provided on the side of the apparatus main body 2 feeds recording materials S one by one toward a registration roller 17 by a feeding unit 8 . The feeding units 7 and 8 have a feeding member such as a feeding roller that feeds out the recording material S from the sheet storage 6 or the manual feed tray, and another recording material S that overlaps the recording material S conveyed by the feeding member. and separation members such as separation rollers or separation pads that apply force to prevent multi-feeding.

The registration roller 17 feeds the recording material S to the secondary transfer portion in synchronization with the toner image forming operation of the image forming portion 3 . The recording material S on which the toner image is secondarily transferred from the intermediate transfer belt 23 in the secondary transfer portion is conveyed to the fixing device 21 . The fixing device 21 fixes the toner image on the recording material S by applying heat and pressure to the toner image on the sheet while nipping and conveying the recording material S. As shown in FIG. In the case of double-sided printing, the recording material S that has passed through the fixing device 21 is guided to the reversing path 26, and is fed again to the image forming section 3 in a state in which the first side and the second side are reversed by switchback conveyance. Images are formed on two sides. In the case of single-sided printing, and when image formation on the second side in double-sided printing is completed, the recording material S that has passed through the fixing device 21 is discharged from the apparatus main body 2 by the discharge rollers 25 .

The image forming unit 3 described above is an example of image forming means for forming an image on a sheet, and a direct transfer type electrophotographic unit or other image forming means such as an inkjet method or an offset printing method may be used.

(Image reader)
Next, the image reading device 1S according to this embodiment will be described. As shown in FIG. 2A, the image reading device 1S reads image information from a document conveying device (Auto Document Feeder, hereinafter referred to as ADF) 10 that feeds a document D, and the document conveyed by the ADF 10. and a reading unit 20 . The ADF 10 is the sheet feeding device of this embodiment. A reading unit 30 serving as reading means of the present embodiment is arranged in the reading section 20 .

The image reading apparatus 1S of this embodiment constitutes a part of the image forming apparatus 1 having a printer function and a scanner function by fixing the reading section 20 to the apparatus main body 2 of the image forming apparatus 1 . However, it is also possible to configure the image reading device 1S described below as an independent device from the image forming device.

The reading unit 20 has a platen glass 201 , a jump table 202 for scooping up the document D from the platen glass 201 , a document platen glass 203 , and a reading unit 30 . The reading unit 30 includes an illumination 306 for illuminating the image surface of the document, mirrors 301, 302, and 303 for guiding reflected and scattered light from the document to an imaging lens 304, and a charge-coupled device 305 as an imaging device. It is a box-shaped unit. Further, the reading unit 30 can be moved in the sub-scanning direction (horizontal direction in the figure) under the platen glass 201 and the document table glass 203 by a belt transmission mechanism.

The ADF 10 includes a document tray 121 , a feeding unit 100 , a registration roller pair 104 , transport roller pairs 105 , 106 and 108 , a discharge roller pair 109 and a discharge tray 122 . The document tray 121 is the sheet stacking portion of this embodiment, and the feeding unit 100 is the sheet feeding means of this embodiment.

A document D whose image is to be read is set on the document tray 121 . The feeding unit 100 has a delivery roller 101 that delivers the document D from the document tray 121, and a separation roller pair (102, 103) that separates and conveys the document D received from the delivery roller 101 one by one. The pair of separation rollers includes a separation driving roller 102 to which a driving force from a motor is input, and a frictional force applied to the document D to prevent multi-feeding. It is composed of a rotating separation driven roller 103 . The registration roller pair 104 is arranged downstream of the separation roller pair in the document D feeding direction. Also, the registration roller pair 104 , the transport roller pairs 105 , 106 , 108 and the discharge roller pair 109 are arranged to deliver and transport the document D in order via the reading position of the reading unit 30 . Documents D discharged by the discharge roller pair 109 are stacked on the discharge tray 122 .

The ADF 10 includes a document set sensor S3 for detecting the document D on the document tray 121, document size sensors S4 and S5 for detecting the size of the document D, and a pair of regulators for aligning the position of the document D on the document tray 121 in the width direction. a plate 123; The regulation plate 123 is movable in the width direction of the document D (direction perpendicular to the feeding direction of the document D by the feeding unit 100). The document size sensor S4 acquires width information of the document D by detecting the position of the regulation plate 123 in the width direction. The document size sensor S5 is a sensor that detects the document D at a predetermined distance upstream from the downstream end of the document tray 121 in the feeding direction, and acquires length information of the document D. FIG. Therefore, the size of the document D can be determined by combining the detection results of the document size sensors S4 and S5.

As the document set sensor S3 and the document size sensor S5, a reflective or transmissive optical sensor capable of detecting the existence of the document D can be used. Also, as the document size sensor S4, for example, a photointerrupter that is shielded by a shield plate provided on the regulation plate 123 can be used.

The ADF 10 also has a first document sensor S1 and a second document sensor S2 for detecting the document D during the feeding operation. As shown in FIG. 3A, the first document sensor S1 is located upstream of the nip position N2 of the registration roller pair 104 and downstream of the nip position N1 of the separation roller pair in the feeding direction X1. The document D is detected at the first detection position). The second document sensor S2 detects the document D at a detection position P2 (second detection position) upstream from the nip position N1 of the pair of separation rollers and downstream from the detection position P3 of the document set sensor S3.

As shown in FIG. 3B, the detection positions P1 and P2 of the first document sensor S1 and the second document sensor S2 are different in the width direction W, and the second document sensor S2 is positioned on the outer side. are doing. However, "outside in the width direction" means that the distance from the transport center line C0, which is the reference position in the width direction W of the document D transported by the ADF, to the detection position P2 of the second document sensor S2 is the transport center line C0. to the detection position P1 of the first document sensor S1. The second document sensor S2 is positioned so as to at least partially overlap with the separation driven roller 103 or its holding member 110 when viewed in the width direction W, and is positioned so as not to interfere with these members. Also, the pair of regulating plates 123 (FIG. 2A) described above can be moved to the inner side of the minimum width detectable by the second document sensor S2.

As the first document sensor S1 and the second document sensor S2, a reflective or transmissive optical sensor capable of detecting the presence of the document D can be used. In the case of these optical sensors, the detection positions P1 and P2 refer to optical axis positions of detection light emitted toward the document D transport space. A photointerrupter for detecting that a flag member projecting toward the transport space is pressed by the document D and swayed can be used as the first document sensor S1 and the second document sensor S2. In this case, the detection positions P1 and P2 refer to the contact positions between the flag member and the document D. As shown in FIG.

FIG. 2B is a block diagram showing the control configuration of the image reading device 1S. A control unit 50 of the image reading device 1S has a central processing unit (CPU) 51 and a memory 52 . The CPU 51 reads and executes a program stored in the memory 52 to control the operation of the image reading device 1S. For example, the CPU 51 issues a command to control the driving states of the feeding motor M1 and the registration motor M2 based on the detection results of the various sensors S1 to S5 according to the flow charts described later. However, the feeding motor M1 is a driving source for the feeding unit 100, and the registration motor M2 is a driving source for the registration roller pair 104. FIG.

Memory 52 includes transient storage media, such as random access memory (RAM), and non-transitory storage media, such as read only memory (ROM) or hard disk drive (HDD). The memory 52 serves as a storage place for programs and data, and also serves as a working space when the CPU 51 executes the programs. Note that the control unit 50 may be mounted inside the image reading device 1S or may be mounted in the device body 2 of the image forming device 1 .

(Image reading operation)
The image reading device 1S selectively selects between a flow reading mode in which the document D placed on the document tray 121 is scanned while being transported by the ADF 10, and a fixed reading mode in which the document placed still on the platen glass 203 is scanned. is executable. The skimming mode is selected when the document set sensor S3 detects the document D stacked on the document tray 121 .

An image reading operation in the skimming mode will be described with reference to FIG. When the image reading operation is started, the delivery roller 101 descends and contacts the uppermost document D on the document tray 121 to deliver the document D. As shown in FIG. The document D is separated sheet by sheet at the nip portion of the pair of separation rollers (102, 103). Here, while the drive force from the motor is supplied to the separation drive roller 102, the separation driven roller 103 is connected to a shaft fixed to the frame of the ADF 10 via a torque limiter. The separation driven roller 103 rotates together with the separation drive roller 102 when the number of originals D entering the nip portion is one, and when two or more originals D enter the nip portion, the driven roller 103 does not rotate and slides the originals by frictional force. Let As a result, only the uppermost document D in contact with the separation driving roller 102 is conveyed.

Note that the separation driven roller 103 is an example of a separation member. Instead of the separation driven roller 103 to which the drive force is not input, a retard roller to which the drive force in the direction opposite to the feeding of the document D (counter direction) is input may be used. Alternatively, the document D may be separated by a friction pad that contacts the separation drive roller 102 instead of the separation driven roller 103 or the retard roller.

The document D that has passed through the nip portion of the separation roller pair has its leading edge (downstream end in the feeding direction) abut against the registration roller pair 104 in a stopped state, thereby correcting the skew. After that, when the registration roller pair 104 starts rotating, the document D is transported toward the platen glass 201 by the transport roller pairs 105 and 106 . In the process of conveying the document D, operation timings of the feeding unit 100 and the registration roller pair 104 are determined based on the detection results of the document D by the first document sensor S1 and the second document sensor S2. For example, the driving start timing of the registration roller pair 104 is determined based on the timing at which the first document sensor S1 detects the leading edge of the document D. FIG. Further, as will be described later, based on the timing at which the first document sensor S1 and the second document sensor S2 detect the passage of the trailing edge of the document D, the lifting/lowering timing of the delivery roller 101 for feeding the next document D is detected. and the driving start timing of the feeding unit 100 is determined.

A guide roller 107 facing the platen glass 201 guides the document D so that it does not float off the platen glass 201 . Image information is read by the reading unit 30 when the document D passes through the platen glass 201 . Specifically, light from illumination 306 is applied to document D being conveyed, and reflected light from document D is guided to imaging lens 304 via mirrors 301 , 302 , and 303 . The light passing through the imaging lens 304 forms an image on the light receiving portion of the charge-coupled device 305 , is photoelectrically converted into an electronic signal by the charge-coupled device 305 , and is transferred to the control board of the image forming apparatus 1 . After passing through the platen glass 201 , the document D is guided to the transport roller pair 108 by the jump table 202 and discharged to the discharge tray 122 by the discharge roller pair 109 .

Note that the fixed reading mode is set when the sensor of the reading unit 20 detects that the document D is placed on the platen glass 203, or when the user explicitly instructs by operating the operation panel of the image forming apparatus 1. It is selected when In the fixed reading mode, the document D is optically scanned while the reading unit 30 moves along the document platen glass 203 while the document D is placed still on the document platen glass 203 . The image information converted into electronic signals by the charge-coupled device 305 is transferred to the control board of the image forming apparatus 1 as in the case of the flow reading mode.

(Document feeding timing)
Next, the feeding timing when feeding a plurality of originals in the flow reading mode will be described. In general, when the ADF 10 sequentially feeds a preceding document and a succeeding document following it, in order to avoid damage due to collision between the documents, the timing at which feeding of the succeeding document does not collide with the preceding document is performed even if feeding of the succeeding document is started. , feeding of the succeeding document is started.

Here, by arranging a plurality of document sensors having different positions in the feeding direction, it is possible to reduce the interval between the preceding document and the succeeding document, thereby improving the productivity of the image reading apparatus 1S. In this embodiment, the detection position P1 of the first document sensor S1 is set downstream of the nip position N1 of the separation roller pair, and the detection position P2 of the second document sensor S2 is set upstream of the nip position N1 of the separation roller pair. (Fig. 3(a)). In this case, when at least one of the first document sensor S1 and the second document sensor S2 changes from detecting the document to not detecting the document after the feeding of the preceding document is started, the subsequent document is detected. Start feeding.

The reason why the productivity is improved by starting the feeding of the succeeding document when at least one of the first document sensor S1 and the second document sensor S2 changes from the detection state to the non-detection state will be explained. First, let us consider a case where the feeding timing of the succeeding document is determined only by the first document sensor S1. That is, after the feeding of the preceding document D1 is started, the state in which the first document sensor S1 detects the document (FIG. 4A) changes from the state in which the document is not detected (FIG. 4B or ( It is assumed that feeding of the succeeding document D2 is started when c)) is changed. In this case, when the subsequent document D2 starts to be fed, there is no document in the section from the nip position N1 of the separation roller pair to the detection position P1 of the first document sensor S1, so collision between the documents is avoided. be. However, as shown in FIG. 4D or 4E, even after the trailing edge of the preceding document D1 is separated from the leading edge of the succeeding document D2 in the feeding direction, the trailing edge of the preceding document D1 is detected by the first document sensor S1. Feeding of the succeeding document D2 does not start until it passes the detection position P1. In other words, the section from the nip position N1 to the detection position P1 is always secured as a margin regardless of whether or not the subsequent document D2 collides with the preceding document D1 when feeding of the succeeding document D2 is started, thereby improving productivity. There is room for

Therefore, if it is possible to start feeding the succeeding document D2 not only when the first document sensor S1 but also the second document sensor S2 changes from the detection state to the non-detection state, the collision between the documents can be prevented. It is possible to reduce the gap between the preceding document D1 and the succeeding document D2 while avoiding this. In this case, as shown in FIGS. 4(d) and 4(e), even before the preceding document D1 passes the detection position P1 of the first document sensor S1, the second document sensor S2 is in the non-detection state. Thus, it can be seen that the preceding document D1 and the succeeding document D2 are separated from each other. Therefore, even if feeding of the succeeding document D2 is started in the states shown in FIGS. 4(d) and (e), collision with the preceding document D1 is avoided. As compared with the case where the feeding timing of the succeeding document is determined only by the first document sensor S1, the feeding of the succeeding document D2 is started in the state shown in FIGS. 4(d) and (e). The feed interval becomes shorter.

It should be noted that in a configuration in which whether or not the subsequent document D2 can be fed is determined only by the second document sensor S2, there is a possibility that the stability of the feeding operation will be impaired. That is, since the detection position P2 of the second document sensor S2 is arranged upstream from the nip position N1 of the pair of separation rollers, the subsequent document D2 is dragged by the preceding document D1 as shown in FIG. 4A. In some cases, it moves to the detection position P2 of the 2-document sensor S2. In this state, the second document sensor S2 does not go into the non-detection state even if the preceding document D1 is sufficiently far away, so it is impossible to determine whether or not feeding of the succeeding document D2 can be started. Error handling is required.

Incidentally, the detection positions P1 and P2 of the first document sensor S1 and the second document sensor S2 are different in width direction as shown in FIG. is located outside in the width direction. Therefore, depending on the size of the document D, the feeding timing cannot be determined appropriately based on the detection results of the first document sensor S1 and the second document sensor S2, and there is a possibility that the documents collide with each other. .

That is, the side edges of the document D shown in FIG. 3B are located inside the detection position P2 of the second document sensor S2 in the width direction W. As shown in FIG. In this case, as shown in FIG. 4F, the second document sensor S2 is in a non-detecting state regardless of the positions of the documents D1 and D2 in the feeding direction. Based on this, if the subsequent document D2 is started to be fed, it may collide with the preceding document D1. FIG. 3B shows a state in which a document D having the shortest length in the width direction W among sizes that can be normally fed by the ADF 10 is set. The size that the ADF 10 can normally feed means, for example, a size that allows the pair of regulating plates 123 to come into contact with the side edges of the document (that is, the side edges of the document are positioned within the movable range of the regulating plates 123). Point.

(Method of controlling document feeding operation)
Therefore, in this embodiment, when feeding a plurality of documents in the skimming mode, the feeding operation mode is changed based on the size of the documents. A method of controlling the feeding operation in this embodiment will be described below with reference to the flowchart of FIG. Unless otherwise specified, the CPU 51 (FIG. 2(b)) of the control unit 50 is the subject that executes the processing of each step of the control method.

The flowchart of FIG. 5 is started, for example, when the user instructs the execution of the copy operation via the operation panel of the image forming apparatus 1 . First, in S101, the detection signal of the document set sensor S3 is confirmed. When documents are stacked on the document tray 121, that is, when the document set sensor S3 is ON (S102: Yes), the feeding operation in the skimming mode (S103 to S115) is executed. If the document set sensor S3 is OFF (S102: No), the ADF 10 does not feed since the fixed reading mode is executed.

In the case of the flow reading mode, the feeding operation mode is selected based on the detection result of the document size sensor S4. That is, when the document width is equal to or larger than the minimum width detectable by the second document sensor S2 (S103: Yes), the first document sensor S1 and the second document sensor S2 are used to determine the feeding timing. A document feeding mode (S104 to S110) is selected. If the width of the document is smaller than the minimum width (S103: No), a second document feeding mode (S111 to S115) is selected in which the feeding timing is determined using only the first document sensor S1.

The "minimum width detectable by the second document sensor S2" means that the side edges of the document D are aligned with the transport center line C0 (FIG. 3B) in the width direction W of the document D. 2 represents the width of the document located outside the detection position P2 of the document sensor S2 by a predetermined distance in the width direction. The size of the predetermined distance defines a margin for allowing the second document sensor S2 to detect the document D stably against variations in document size and document set position. It is appropriately set as product specifications. The predetermined distance may be 0 mm. An example of a size larger than the minimum width (first size) is A5, and an example of a size smaller than the minimum width (second size) is a postcard (both widths are the length of the short side).

1. First Document Feeding Mode In the first document feeding mode, after starting the feeding of the topmost document D (S104), detection signals of the first document sensor S1 and the second document sensor S2 are checked. (S105, S107). If both sensors S1 and S2 are in the detection state (ON) (S106: No and S108: No, see FIG. 4A), it is determined that the next document D cannot be fed, and The feeding operation for the document D is not started. In this case, for example, the delivery roller 101, which is separated above the document after the document D, which is the uppermost document, is held at the upper position without being lowered.

On the other hand, if one of the sensors S1 and S2 changes from the detection state (ON) to the non-detection state (OFF) after the start of feeding (S106: Yes or S108: Yes, see FIGS. 4B to 4E) ), it is determined that the next document D can be fed. In this case, the document set sensor S3 confirms whether or not there is the next document D (S109), and if there is the next document D (S110: Yes), feeding of the next document D is started. (S104). The processing of S104 to S110 described above is repeated until all the documents D stacked on the document tray 121 are fed. When the last document D is fed and it is confirmed that there is no next document D (S110: No), the process ends.

In the first document feeding mode, as shown in FIG. 4(e), when the trailing edge of the preceding document D1 is downstream of and in the vicinity of the detection position P2 of the second document sensor S2, the following document D2 is detected. When the feeding of the originals is started, the space between the originals becomes narrow. Here, in the present embodiment, the transport speed of the preceding document by the registration roller pair 104 (peripheral speed of the rollers) is set to a value greater than the transport speed of the subsequent document by the separation roller pair (peripheral speed of the separation driving roller 102). It is That is, the conveying speed of the downstream sheet conveying means is set higher than the conveying speed of the sheet feeding means. Therefore, even if the space between the documents transported at the same time is temporarily narrowed as shown in FIG. 4E, collision between the documents can be avoided because the space widens due to the transport speed difference.

As a modification, the conveying speed of the sheet feeding means may be set to be equal to or higher than the conveying speed of the sheet conveying means on the downstream side, or the sheet conveying means on the downstream side may be set to temporarily stop. . In this case, if the feeding of the succeeding document D2 is started immediately after the second document sensor S2 becomes non-detected, the documents may collide with each other. An appropriate waiting time is set before starting the feeding of the succeeding document D2. As a method of setting the waiting time, there is a method of waiting until the first document sensor S1 becomes non-detected, or a method of monitoring the amount of rotation of the motor that drives the sheet conveying means on the downstream side and confirming that the preceding document D1 is sufficiently conveyed. There is a method of waiting until it is confirmed that it is.

2. Second Document Feeding Mode In the second document feeding mode, after starting the feeding of the top document D (S111), the detection signal of the first document sensor S1 is confirmed (S112). When the first document sensor S1 is in the detection state (ON) (S113: No, see FIGS. 4(a), (d) to (f)), it is determined that the next document D cannot be fed. , the feeding operation for the next document D is not started. At this time, unlike the first document feeding mode, even if the second document sensor S2 is in a non-detecting state (FIGS. 4(d) to (f)), the feeding operation for the next document D starts. not.

When the first document sensor S1 changes from the detection state (ON) to the non-detection state (OFF) after the start of feeding (S113: Yes, see FIGS. 4B and 4C), the next document D is fed. determined to be ready for transmission. In this case, the document set sensor S3 confirms whether or not there is the next document D (S114), and if there is the next document D (S115: Yes), feeding of the next document D is started. (S111). The processing of S111 to S115 described above is repeatedly executed until all the documents D stacked on the document tray 121 are fed. When the last document D is fed and it is confirmed that there is no next document D (S115: No), the process ends.

(Summary of this embodiment)
In the present embodiment, the first document feeding mode, which is the first mode of the present embodiment, is executed when a first size document is fed, and a second size document having a width smaller than the first size document is fed. When the document is to be fed, the second document feeding mode, which is the second mode of the present embodiment, is executed. An example of the first size is a postcard and an example of the second size is A5.

In the first document feeding mode, after the feeding unit 100 starts feeding the preceding document (preceding sheet), at least one of the first document sensor S1 and the second document sensor S2 changes from the detection state to the non-detection state. Then, feeding of the succeeding document (subsequent sheet) is started. As a result, the feeding interval is shortened while avoiding the collision of the originals, which contributes to the improvement of the productivity of the image reading apparatus 1S. On the other hand, in the second document feeding mode, after the feeding unit 100 starts feeding the preceding document, the first document sensor S1 changes from the detection state to the non-detection state regardless of the detection result of the second document sensor S2. When it changes, feeding of the succeeding document is started. As a result, it is possible to avoid collisions between documents and realize a stable feeding operation even for documents having a short width. Therefore, according to this embodiment, it is possible to improve productivity while realizing a stable feeding operation for various sheets having different sheet widths.

(Modification)
In the above-described embodiment, the document size sensor S4 that detects the position of the regulation plate 123 that regulates the position of the document is used as the size acquisition unit that acquires information about the length of the sheet in the width direction. It is also possible to use means. For example, when the document size is explicitly input via the operation panel or the like of the image forming apparatus 1, the first document feeding mode or the second document feeding mode is executed based on the input document size. may In this case, an input device such as a numeric keypad or a touch panel for accepting input of the document size serves as the size acquisition means.

Further, in the above-described embodiment, the detection position P2 of the second document sensor S2 is located upstream of the nip position N1 of the pair of separation rollers in the feeding direction. It may be arranged downstream from the position N1. Also in this case, the timing at which the second document sensor S2 changes from the detection state to the non-detection state after the start of feeding of the preceding document is earlier than the timing at which the first document sensor S1 changes from the detection state to the non-detection state. Therefore, if at least one of the first document sensor S1 and the second document sensor S2 changes from the detection state to the non-detection state in the first document feeding mode, feeding of the succeeding document can be started. It is possible to shorten the feed interval while avoiding the collision of the .

Further, the image reading apparatus 1S may have a mode other than the first document feeding mode and the second document feeding mode as the document feeding operation in the skimming mode. For example, a plurality of types of documents having different lengths in the width direction are stacked in contact with one side wall of the document tray 121, and the document size is automatically determined based on the size of the scanned image. A mode (mixed loading mode) to be discriminated is exemplified. The timing to start feeding the next document in the mixed loading mode can be determined, for example, by using the sensor closer to the side wall of the first document sensor S1 and the second document sensor S2 with which the document comes into contact. be.

Also, the techniques described in the above-described embodiment and its modification can be applied to sheet feeding devices other than the image reading device, including the cassette feeding section 4 and the manual feeding section 5 (FIG. 1). .

(Other embodiments)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

1 image forming apparatus/1S image reading apparatus/3 image forming means (image forming section)/4, 5, 10 sheet feeding apparatus (ADF, cassette feeding section, manual feeding section)/30 reading Means (Reading Unit)/50 Control Means (Control Section)/100 Sheet Feeding Means (Feeding Unit)/101 Delivery Roller/102 Conveying Roller (Separation Drive Roller)/103 Separation Member (Separation Driven Roller) )/104 Sheet conveying means (registration roller pair)/121 Sheet stacking portion (document tray)/123 Regulating plate/N1 Nip position/P1 First detection position/P2 Second detection position/S1 First detection means (first document sensor)/S2 Second detection means (second document sensor)/S4 Size acquisition means (document size sensor)

According to one aspect of the present invention, a sheet stacking unit on which sheets are stacked, a sheet feeding unit that feeds sheets from the sheet stacking unit in a feeding direction, and a sheet that is fed by the sheet feeding unit is fed by the sheet stacking unit. A first detection means for detecting at one detection position, and a second detection means outside the first detection position in the width direction perpendicular to the feeding direction and upstream of the first detection position in the feeding direction. second detecting means for detecting the sheet at the position; and when the width of the sheet to be fed is the first width, the first detecting means after the sheet feeding means starts feeding the preceding sheet. and determining the detection state of the second detection means, and detecting the subsequent sheet when at least one of the first detection means and the second detection means changes from a state in which the sheet is detected to a state in which the sheet is not detected. When the width of the sheet to be fed is a second width smaller than the first width, after the sheet feeding means starts feeding the preceding sheet, the first 2. Regardless of the detection result of the second detection means, the sheet feeding is configured to start feeding the subsequent sheet when the state where the first detection means detects the sheet changes to the state where the first detection means does not detect the sheet. and a control means for controlling the feeding means.

Claims (8)

a sheet stacking unit on which sheets are stacked;
a sheet feeding means for feeding the sheet from the sheet stacking portion in the feeding direction;
a first detection means for detecting the sheet fed by the sheet feeding means at a first detection position;
second detection means for detecting the sheet at a second detection position outside the first detection position in the width direction perpendicular to the feeding direction and different from the first detection position in the feeding direction;
a size acquiring unit for acquiring information about the length of the sheets stacked on the sheet stacking unit in the width direction;
a control means for controlling the sheet feeding means based on the information obtained by the size obtaining means;
The control means is
When at least one of the first detection means and the second detection means changes from detecting the sheet to not detecting the sheet after the sheet feeding means starts feeding the preceding sheet. a first mode in which feeding of subsequent sheets is started at
After the sheet feeding means starts feeding the preceding sheet, regardless of the detection result of the second detecting means, the state in which the first detecting means detects the sheet changes to the state in which the sheet is not detected. a second mode of initiating feeding of subsequent sheets when changed;
The first mode is executed when a sheet of a first size is fed, and the second mode is executed when a sheet of a second size whose length in the width direction is shorter than that of the first size sheet is fed. Execute,
A sheet feeding device characterized by: further comprising: a regulating plate provided movably in the width direction on the sheet stacking unit and regulating the position of the sheets stacked on the sheet stacking unit in the width direction;
The size acquisition means is a sensor that detects the position of the regulation plate,
2. The sheet feeding apparatus according to claim 1, wherein: The sheet feeding means includes a conveying roller that conveys a sheet, and a separation member that contacts the conveying roller and separates the sheet conveyed by the conveying roller,
The second detection means is positioned so as to overlap at least one of the conveying roller and the separation member when viewed in the width direction.
3. The sheet feeding device according to claim 1, wherein: The sheet feeding means includes a delivery roller provided upstream of the transport roller in the feeding direction and delivering the sheet from the sheet stacking section toward the transport roller,
The first detection position is set downstream from a nip position between the conveying roller and the separating member in the feeding direction, and the second detection position is set upstream from the nip position.
4. The sheet feeding device according to claim 3, wherein: The first detection position is set to a position through which a sheet having the shortest length in the width direction among sheets that can be fed by the sheet feeding device passes in the width direction.
5. The sheet feeding apparatus according to claim 1, wherein: a sheet conveying means for receiving and conveying a sheet from the sheet feeding means;
When the sheet conveying means conveys the preceding sheet and the sheet conveying means conveys the succeeding sheet, the conveying speed of the sheet conveying means is set higher than the conveying speed of the sheet conveying means. there is
6. The sheet feeding device according to any one of claims 1 to 5, characterized in that: A sheet feeding device according to any one of claims 1 to 6;
reading means for reading image information from the sheet fed by the sheet feeding device;
An image reading device characterized by: A sheet feeding device according to any one of claims 1 to 6;
and an image forming means for forming an image on the sheet,
An image forming apparatus characterized by:

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