JP2019153983A - Sheet transfer device, image reading device, and image formation device - Google Patents

Abstract

To provide a document transfer device, an image reading device, and an image formation device that can predict the sheet size of a placed sheet even if the sheet placed on a loading part is bent.SOLUTION: A sheet transfer device includes first detection means for detecting whether there is a sheet placed on a sheet loading stand on which a sheet can be loaded; second detection means for detecting whether there is a sheet at an upstream side of the first detection means in a sheet transfer direction; and prediction means for predicting the sheet size of the sheet on the basis of a detection result of the second detection means when the detection result of the second detection means changes from the state of no sheet between before starting transfer of the sheet and after starting transfer.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a sheet conveying apparatus, an image reading apparatus, and an image forming apparatus.

  Reading means for reading an original, original feeding means for feeding an original to the reading means, paper storage means for storing paper, printing means for printing on paper stored in the paper storage means, and size of the original Predicting means for predicting the image based on the size of the paper stored in the paper storing means, and control means for causing the original feeding means to feed the original and causing the reading means to read the original in the size expected by the predicting means And a specifying unit that specifies the size of the document fed by the document feeding unit, and the control unit is configured to supply the document when the size specified by the specifying unit and the size predicted by the prediction unit are different. There is known an image forming apparatus that causes a feeding unit to re-feed a document and causes a reading unit to read the document at a size specified by a specifying unit (Patent Document 1).

JP 2013-42393 A

In a state where the sheet placed on the stacking unit is folded, the sheet detection sensor arranged at the portion where the sheet floats from the stacking unit may not detect.
The present invention provides a document conveying apparatus, an image reading apparatus, and an image forming apparatus capable of predicting the sheet size of a placed sheet even when the sheet placed on the stacking unit is folded. For the purpose.

In order to solve the above-described problem, a sheet conveying device according to claim 1,
First detecting means for detecting the presence or absence of the sheet placed on a sheet stacking table on which sheets can be stacked;
Second detection means for detecting the presence or absence of the sheet upstream of the first detection means in the sheet conveyance direction;
If the detection result of the second detection unit changes from the state of no sheet before and after the start of conveyance of the sheet, the sheet size of the sheet is predicted based on the detection result of the second detection unit A prediction means for
It is characterized by that.

The invention according to claim 2 is the sheet conveying apparatus according to claim 1,
The predicting unit is configured such that the sheet is placed on the sheet stacking table, the second detecting unit does not detect the presence / absence of the sheet, and after the sheet is conveyed, the second detecting unit is within a predetermined time. When the presence of a sheet is detected, the sheet size of the sheet is predicted based on the detection result of the second detection unit.
It is characterized by that.

The invention according to claim 3 is the sheet conveying apparatus according to claim 1,
The predicting unit is configured such that the sheet is placed on the sheet stacking table, the presence or absence of the sheet is not detected by the second detection unit, and the second detection unit within a predetermined time after conveying the sheet. If the presence or absence of the sheet is not detected, predict the sheet size of the sheet based on the detection result of the first detection means;
It is characterized by that.

The invention according to claim 4 is the sheet conveying apparatus according to claim 2 or 3,
The predetermined time is D / V + α.
It is characterized by that.
Here, the distance in the conveyance direction between the sheet trailing edge of the maximum length of the sheet and the second detection unit is D, the sheet conveyance speed is V, and α is a preset time.

The invention according to claim 5 is the sheet conveying apparatus according to any one of claims 1 to 4,
A third detection unit that detects a sheet width that is a length in a direction orthogonal to a conveyance direction of the sheet placed on the sheet stacking table;
The prediction means predicts the sheet size of the sheet from the detection results of the second detection means and the third detection means;
It is characterized by that.

The invention according to claim 6 is the sheet conveying apparatus according to any one of claims 1 to 5,
A fourth detection unit configured to detect a length related to a conveyance direction of the sheet conveyed downstream of the first detection unit in the conveyance direction of the sheet;
The predicting means predicts the sheet size of the sheet from the detection results of the first detecting means and the third detecting means when the trailing edge of the sheet is detected by the fourth detecting means;
It is characterized by that.

In order to solve the problem, an image reading apparatus according to claim 7,
Reading means for reading an image of the sheet;
The sheet conveying device according to any one of claims 1 to 6, wherein the reading unit conveys the sheet to a reading position where the sheet is read.
It is characterized by that.

In order to solve the above problem, an image forming apparatus according to claim 8,
An image reading apparatus according to claim 7 for reading an image on a sheet;
Image recording means for recording an image read by the image reading device on a recording medium,
It is characterized by that.

  According to the first, seventh, and eighth aspects of the invention, if the detection result of the second detection means changes from the state of no sheet before and after the start of conveyance of the sheet, the detection of the second detection means. Compared to the case where there is no prediction means for predicting the sheet size of the sheet based on the result, the sheet size of the placed sheet is predicted even when the sheet placed on the stacking unit is folded. be able to.

  According to the second aspect of the present invention, the sheet size of the placed sheet can be predicted even when the sheet placed on the stacking unit is folded.

  According to the invention described in claim 3, it is possible to suppress erroneous detection of the sheet size of the placed sheet.

  According to the fourth aspect of the present invention, even a folded sheet can detect the sheet placed on the stacking unit.

  According to the invention described in claim 5, it is possible to predict the sheet sizes of sheets having different lengths in the width direction.

  According to the sixth aspect of the present invention, erroneous detection of the sheet size can be suppressed when no sheet is placed on the stacking unit.

1 is a schematic cross-sectional view showing an internal configuration of an image forming apparatus. It is a cross-sectional block diagram which shows the internal structure of a reading part. 2 is a block diagram illustrating an example of a functional configuration of an image forming apparatus. FIG. 3 is a perspective view illustrating a document stacking unit of the image reading apparatus. FIG. FIG. 4 is a schematic cross-sectional view illustrating the configuration of a document stacking unit and a separation unit. FIG. 3 is a schematic plan view showing the arrangement of document detection sensors in a document stacking unit. 6 is a diagram illustrating an example of a document size detection pattern. FIG. It is a perspective view showing an actuator and an optical sensor of a first document length detection sensor and a second document length detection sensor. It is explanatory drawing explaining the time when a 2nd original length detection sensor detects a Z fold original. 6 is a flowchart showing a flow of operations for predicting the size of a document. FIG. 6 is a perspective view showing a state in which a Z-fold original is placed on an image reading apparatus having a first original length detection sensor and a second original length detection sensor.

Next, the present invention will be described in more detail with reference to the drawings with reference to embodiments and specific examples. However, the present invention is not limited to these embodiments and specific examples.
Also, in the description using the following drawings, it should be noted that the drawings are schematic and the ratio of each dimension and the like are different from the actual ones, and are necessary for the description for easy understanding. Illustrations other than the members are omitted as appropriate.

(1) Overall Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic cross-sectional view showing the internal configuration of the image forming apparatus 1 according to this embodiment, FIG. 2 is a cross-sectional configuration diagram showing the internal configuration of the image reading apparatus 2, and FIG. FIG. 2 is a block diagram illustrating an example of a functional configuration of the image forming apparatus 1. Hereinafter, the overall configuration and operation of the image forming apparatus 1 will be described with reference to the drawings.

(1.1) Overall Configuration The image forming apparatus 1 includes an image reading apparatus 2 that reads an image from a document and converts the image into image data, and an image forming unit as an image recording unit that prints the read image data on a sheet as a recording medium. 3. An operation information unit 4 as a user interface and an image processing unit 5 are provided.

  The image reading apparatus 2 includes a document stacking unit 21, an automatic document feeding unit 22, and an image reading unit 23. The automatic document feeder 22 conveys the document G placed on the document stacking unit 21 to the reading position of the image reading unit 23, and an image sensor (not shown) such as a CCD (Charge Coupled Device) line sensor in the image reading unit 23. The image read in is converted into image data which is an electric signal.

  The image forming unit 3 includes a paper feeding device 31, an exposure device 32, a photosensitive unit 33, a developing device 34, a transfer device 35, and a fixing device 36, and receives image information received from the image processing unit 5 as a paper feeding device. The toner image is formed on the paper P fed from the paper 31.

  An operation information unit 4 as a user interface is disposed on the front side of the image reading device 2. The operation information unit 4 is configured by combining a liquid crystal display panel, various operation buttons, a touch panel, and the like, and the user of the image forming apparatus 1 can perform various settings and instructions via the operation information unit 4 as an example of a reception unit. Make input. Various information is displayed to the user of the image forming apparatus 1 via the liquid crystal display panel.

  The image processing unit 5 generates image data from the image read by the image reading device 2 and print information transmitted from an external device (for example, a personal computer).

(1.2) Image Reading Device The image reading device 2 includes a document stacking unit 21, an automatic document feeding unit 22, and an image reading unit 23. The document stacking unit 21 and the automatic document feeding unit 22 are connected to the image reading unit 23 so as to be openable and closable.

  The document stacking unit 21 includes a document tray 212 on which a document G on which an image is recorded is placed. The document tray 212 can be moved up and down according to the number of documents G to be placed, and holds the document G at a position where the upper surface of the document G is raised so as to contact the nudger roller 221.

The automatic document feeder 22 includes a nudger roller 221 that sequentially takes out the documents G stacked on the document tray 212 from above, a feed roller 222 as a feed roller, and a retard roller 223 as a separation roller that is in pressure contact with the feed roller 222. Part 224 is provided.
In the separation unit 224, when the feed roller 222 and the retard roller 223 are paired and the original G is overlapped and sent to the nip portion N, the original G is separated (turned), and image reading is performed one by one. To the unit 23.

  In the transport path S, a transport roller 225 is disposed at a position downstream of the feed roller 222 with respect to the transport direction of the document G. The conveyance roller 225 conveys the original G sent out by the feed roller 222 to the pre-registration roller 226.

A feedout sensor S4 is provided on the upstream side of the transport roller 225. The feedout sensor S4 is configured by using a reflection type optical sensor, and detects the leading edge of the document G, so that the document G conveyed from the separation unit 224 is abutted against the stopped conveyance roller 225 to form a loop. It is a trigger to do. A feed amount corresponding to a predetermined number of pulses is set after the feed-out sensor S3 is turned on, and a loop is formed on the document G.
The size of the transported original G in the feed direction is detected by the time from when the transport roller 225 is driven to rotate until the trailing edge of the original G passes through the feedout sensor S4 and the feedout sensor S4 is turned off. The

  On the downstream side of the pre-registration roller 226, a registration roller 227 for adjusting the conveyance timing of the document G is disposed. The pre-registration roller 226 corrects skew by forming a loop with the leading edge of the document G abutting against the stopped registration roller 227. The registration roller 227 is driven to rotate in accordance with the reading start timing, and the document G is pressed against the document passage surface PG1 by the platen roller 228 while the loop is held by the transport roller 225 and the pre-registration roller 226, and the image is read on the surface. Read by the unit 23.

  A document placement surface PG2 for supporting the document G placed by the operator is arranged on the right side of the document passage surface PG1. A document guide PG3 is disposed between the document passage surface PG1 and the document placement surface PG2, and the document G that has passed through the document passage surface PG1 is guided by the document guide PG3 and conveyed to the reading sensor 232. The The original G whose surface is read by the image reading unit 23 is discharged to a paper discharge unit 217 formed below the original stacking unit 21 by a discharge roller 229 while the back surface is read by a reading sensor 232.

  An image reading sensor 231 that optically reads an image of the document G and converts it into an electrical signal is provided below the document placement surface PG22, and the document G passing on the document passage surface PG1 or The image of the original G placed on the original placement surface PG2 is read. The read image is converted into image data that is an electrical signal.

(1.3) Image Forming Unit In the image forming unit 3, the paper P designated for each printing sheet by the print job is sent from the paper feeding device 31 to the image forming unit 3 in accordance with the timing of image formation.

  The photoconductor unit 33 includes a photoconductor drum 341 that is provided in parallel above the paper feeding device 31 (in the Z direction) and is driven to rotate. On the respective photosensitive drums 341 on which the electrostatic latent images are formed by the exposure device 32, yellow (Y), magenta (M), cyan (C), and black (K) toner images are developed by the respective developing devices 34. Is formed.

  Each color toner image formed on the photoconductive drum 341 of each photoconductor unit 33 is sequentially electrostatically transferred (primary transfer) onto the intermediate transfer belt 361 of the transfer device 35 to form a superimposed toner image in which the respective color toners are superimposed. Is done. The superimposed toner image on the intermediate transfer belt 361 is sent out from the registration roller pair 321 and is collectively transferred by the secondary transfer roller 362 onto the paper P guided by the conveyance guide.

In the fixing device 36, a fixing nip FN (fixing region) is formed by a pressure contact region between the pair of heating modules 371 and the pressure module 372.
The paper P onto which the toner images are collectively transferred in the transfer device 35 is transported to the fixing nip FN of the fixing device 36 through the transport guide 363 with the toner images being unfixed, and a pair of heating modules 371 and pressure modules 372 are transported. Thus, the toner image is fixed by the action of pressure bonding and heating.

  The sheet P on which the fixing toner image is formed is guided by the switching gate G1, and is discharged / accommodated from the first discharge roller pair 373 to the discharge tray portion TR1 on the upper surface of the image forming apparatus 1. When the paper is reversed for duplex printing or discharged with the image recording surface facing upward, the conveyance direction is switched toward the conveyance path 375 by the switching gate G1.

(1.3) Block Configuration of Image Forming Apparatus The image forming apparatus 1 includes a system control apparatus 10 including an image output control unit 11, a reading control unit 12, a power supply control unit 13, an exposure control unit 14, and a fixing temperature control unit 15. And controlling the operation of the entire image forming apparatus 1 by executing a control program stored in the memory.

The image output control unit 11 gives an operation control instruction to the paper feeding device 31, the exposure device 32, the photoconductor unit 33, the developing device 34, the transfer device 35, the fixing device 36 and the like provided in the image forming unit 3.
Further, the image output control unit 11 gives operation control instructions to the power supply control unit 13, the exposure control unit 14, and the fixing temperature control unit 15 included in the system control apparatus 10. That is, it is determined whether or not to supply power to and drive the paper feeding device 31, the exposure device 32, the photosensitive unit 33, the developing device 34, the transfer device 35, the fixing device 36, and the like constituting the image forming unit 3. The determination result is instructed to each control unit.

  Further, the image output control unit 11 exchanges information with the reading control unit 12, and performs a predetermined image reading control when receiving an image reading instruction via the operation information unit 4.

  The reading control unit 12 controls the operation of the image reading device 2 and scans an image of the document G by scanning while conveying the document G stacked on the document stacking unit 21 to the image reading unit 23 via the automatic document feeding unit 22. Read and accept the read image data. The received image data is stored in a storage unit (HDD).

(2) Configuration and Operation of Document Stacking Unit FIG. 4 is a perspective view showing the document stacking unit 21 of the image reading apparatus 2, FIG. 5 is a schematic sectional view showing the configuration of the document stacking unit 21 and the separation unit 224, and FIG. FIG. 7 is a schematic plan view showing the arrangement of document detection sensors in the stacking unit 21, and FIG. 7 is a diagram showing an example of a document size detection pattern. Hereinafter, the configuration and operation of the document stacking unit 21 will be described with reference to the drawings.

(2.1) Configuration of Document Loading Unit The image reading apparatus 2 includes a document stacking unit 21, and the automatic document feeding unit 22 separates the documents G sent from the document stacking unit 21 by the nudger roller 221 one by one. The image is sent to the image reading unit 23.

  The document stacking unit 21 supports the document tray 212 on the tray main body 211 so that the document tray 212 can be moved up and down. The document stacking unit 21 has a document length that is a distance along the document transport direction (arrow R in FIGS. 5 and 6). Documents that differ in at least one of the document widths that are distances along the direction intersecting (orthogonal) with the transport direction can be stacked.

As shown in FIG. 5, a document edge aligning section 213 is formed on the document delivery side of the tray body 211. One end side of the document G stacked on the upper surface 212a of the document tray 212 (the front end side in the document transport direction) is brought into contact with the document edge aligning portion 213 so that the leading edges are aligned.
A center registration system is adopted in which a pair of side guides 215 are movably arranged in a direction intersecting (orthogonal) with the document conveyance direction, and the side edges in the document width direction are aligned in the width direction with reference to the side guide 215. ing.

  As shown in FIGS. 5 and 6, the document stacking unit 21 includes a document width detection sensor SNR <b> 1 that detects the document width of the document G placed on the document tray 212. The document width detection sensor SNR1 includes three optical sensors S1, S2, and S3 arranged along an actuator (not shown) that moves together with the side guide 215 as the side guide 215 slides. The relative positional relationship between the actuator and each of the optical sensors S1, S2, and S3 is set so that the on / off state of the three optical sensors S1, S2, and S3 is switched in eight patterns depending on the position of the side guide 215. .

  Further, as shown in FIG. 4, the document stacking unit 21 is provided with a first document length detection sensor SNR2 and a second document length detection sensor SNR3 for detecting the document length of the document G placed on the document tray 212. Yes. The first document length detection sensor SNR2 and the second document length detection sensor SNR3 are arranged along the conveyance direction of the document G on the document tray 212, and detect the document length of the document G placed on the document tray 212. .

  Regardless of the size difference of the original G, all the originals G are placed on the original tray 212 in a state where the leading end positions of the originals G are aligned. For this reason, the trailing edge position of the document G depends on the document length of the document placed on the document tray 212, and the trailing edge position of the document with a long document length is shorter than the trailing edge position of the document with a short document length. It is located away from 221.

The first document length detection sensor SNR2 is disposed at a position close to the nudger roller 221, and the second document length detection sensor SNR3 is disposed at a position far from the nudger roller 221 on the upstream side of the first document length detection sensor SNR2 in the document transport direction. ing. Thus, the first document length detection sensor SNR2 detects the document G having a short document length, and the second document length detection sensor SNR3 detects the document G having a long document length.
The relative positional relationship is set so that the on / off state of the first document length detection sensor SNR2 and the second document length detection sensor SNR3 is switched in three patterns depending on the document length of the document G.

  For example, when a document G having a document length corresponding to a short size of A5 size (182 mm: A5L) is placed on the document tray 212, both the first document length detection sensor SNR2 and the second document length detection sensor SNR3 are turned off. When the original G corresponding to the A4 size longitudinal dimension (297 mm: A4S) is placed on the original tray 212, the first original length detection sensor SNR2 is turned on and the second original length detection sensor SNR3 is turned off. When the document G having a document length corresponding to the longitudinal dimension of A3 size (420 mm: A3S) is placed on the document tray 212, both the first document length detection sensor SNR2 and the second document length detection sensor SNR3 are turned on. The first document length detection sensor SNR2 and the second document length detection sensor SNR3 shift the positions in the conveyance direction of the document G in a positional relationship that satisfies the condition. It is located.

  The document G placed on the document tray 212 by the document width detection sensor SNR1, the first document length detection sensor SNR2, and the second document length detection sensor SNR3 arranged in this way has 24 patterns as shown in FIG. This corresponds to one of them, and the size of the original G can be predicted.

(2.2) Document Length Detection Sensor FIG. 8 is a perspective view showing the actuator 100 and the optical sensor SN1 of the first document length detection sensor SNR2 and the second document length detection sensor SNR3.
The first document length detection sensor SNR2 and the second document length detection sensor SNR3 have an actuator 100 (see FIG. 4) protruding upward from the upper surface 212a of the document tray 212.

  As shown in FIG. 8A, the actuators 100 of the first document length detection sensor SNR2 and the second document length detection sensor SNR3 project from the document tray 212 and come into contact with the document G, and the detection unit 101. A weight part 103 that tilts the detecting part 101 in the direction opposite to the direction of gravity and a light shielding part 104 that protrudes from one end of the weight part 103 is provided. In a state where the detection is not performed, the detection unit 101 protrudes from the document tray 212. The actuator 100 can appropriately set the weight of the weight portion 103 so that it tilts with the weight of the document G when the document G contacts the detection unit 101.

  The first document length detection sensor SNR2 and the second document length detection sensor SNR3 having the actuator 100 configured as described above are configured such that when the document G is placed on the document tray 212 and contacts the document G, the actuator 100 rotates. The original G is detected when the optical sensor SN1 is turned on.

  FIG. 11 shows a state in which the Z-fold original G is placed on the image reading apparatus 2 having the first original length detection sensor SNR2 and the second original length detection sensor SNR3. As shown in FIG. 11, when the document G placed on the document tray 212 is a folded document (hereinafter referred to as a Z-fold document), a folded portion of the document G (illustrated by an arrow in the figure). ) Is separated from the upper surface 212a of the document tray 212, for example, the document G may not be detected without contacting the actuator 100 of the second document length detection sensor SNR3.

(3) Prediction of Document Size FIG. 9 is an explanatory diagram for explaining the time for the second document length detection sensor SNR3 to detect a Z-fold document, and FIG. 10 is a flowchart showing the flow of operations for predicting the size of the document G. Hereinafter, document size prediction in the image reading apparatus 2 and the image forming apparatus 1 will be described with reference to the drawings.

  When reading an image of the document G, the user of the image forming apparatus sets the document G so that the document G is aligned with the pair of side guides 215 and the document edge aligning unit 213 on the front side in the document transport direction.

  When the document G is set on the document tray 212 of the document stacking unit 21 and the document width detection sensor SNR1 or the first document length detection sensor SNR2 is turned on (S101: Yes), the reading control unit 12 turns on the document tray 212. The size A of the original G placed on the printer is predicted (S102). The size A of the original G is determined based on, for example, the table shown in FIG. 7 by turning on or off the original width detection sensor SNR1 (S1, S2, S3), the first original length detection sensor SNR2, and the second original length detection sensor SNR3. Predicted by state.

  Then, it is determined whether or not the second document length detection sensor SNR3 is on (S103). When the second document length detection sensor SNR3 is on (S103: Yes), the placed document G is in contact with the second document length detection sensor SNR3 in the length direction, and thus predicted in step 102. It is assumed that the size is A and is conveyed as it is (S104).

On the other hand, when the second document length detection sensor SNR3 is off (S103: No), the placed document G is not in contact with the second document length detection sensor SNR3 in the length direction, and therefore, from B4S / A3S. Is a short document, or B4S / A3S, and is estimated to be a Z-fold document. For this purpose, the document G is conveyed (S104), and it is determined whether or not the second document length detection sensor SNR3 is turned on within a predetermined time T (S105).
Here, as shown in FIG. 9, the predetermined time T is a distance D in the conveyance direction between the maximum document trailing edge GE of the document G and the second document length detection sensor SNR3, and a conveyance speed of the document G is V. Where T = D / V + α. α is a preset time.

  If the second document length detection sensor SNR3 is turned on within the predetermined time T (S105: Yes), the document G is estimated to be a Z-fold document (B4S / A3S), and the size A of the document G is set to step 102. The size A predicted in (1) is overwritten (S107). At this time, the width direction is determined according to the detection state of the document width detection sensor SNR1, and is predicted to be B4S or A3S. Thereby, even if the placed original G is a Z-fold original, the size can be predicted.

  The document G whose size A is predicted is abutted against the conveying roller 225 to form a loop, and then conveyed to the pre-registration roller 226. At this time, the size of the document G in the feed direction is detected based on the time from when the feedout sensor S4 is turned on to when it is off, and the size B of the document G is specified (S107). When the feedout sensor S4 is turned off, detection of SNR1, SNR2, and SNR3 is not accepted (S108). Thereby, when the document G is not placed on the document tray 212 of the document stacking unit 21, erroneous detection of the document size due to the tilting of the actuator 100 is suppressed.

  Then, the size A predicted in step 102 or the size A overwritten in step 106 is compared with the size B specified based on the detection result of the feedout sensor S4 (S109), and the size A and the size B are compared. Are the same (S109: Yes), the size prediction of the document G is determined (S110). When size A and size B do not match (S109: No), preset jam processing or document discharge is performed (S111). Then, image reading is performed with the document size predicted in this way.

As described above, when the detection result of the second document length detection sensor SNR3 changes from the state of no document (off) before and after the conveyance of the document G starts, the image reading apparatus 2 and the image forming apparatus 1 The size of the document G is predicted based on the detection result of the second document length detection sensor SNR3.
Specifically, the document G is placed on the document tray 212, the presence or absence of the document G is not detected by the second document length detection sensor SNR3, and after the document G is conveyed, the second document length detection sensor SNR3 is set for a predetermined time T. When the presence of a document is detected, the size of the document G is predicted based on the detection result of the second document length detection sensor SNR3. Can be predicted.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Image reading apparatus 21 ... Document stacking part 211 ... Tray body 212 ... Document tray SNR1 ... Document width detection sensor S1, S2, S3 ... Light Sensor SNR2: First document length detection sensor SNR3: Second document length detection sensor 100: Actuator
SNR4 ... feedout sensor
213: Document edge aligning unit 22 ... Automatic document feeding unit 23 ... Image reading unit 3 ... Image forming unit 4 ... Operation information unit 5 ... Image processing unit 10 ... System control Apparatus 11 ... Image output control unit 12 ... Reading control unit

Claims (8)

First detecting means for detecting the presence or absence of the sheet placed on a sheet stacking table on which sheets can be stacked;
Second detection means for detecting the presence or absence of the sheet upstream of the first detection means in the sheet conveyance direction;
If the detection result of the second detection unit changes from the state of no sheet before and after the start of conveyance of the sheet, the sheet size of the sheet is predicted based on the detection result of the second detection unit A prediction means for
A sheet conveying apparatus. The predicting unit is configured such that the sheet is placed on the sheet stacking table, the second detecting unit does not detect the presence / absence of the sheet, and after the sheet is conveyed, the second detecting unit is within a predetermined time. When the presence of a sheet is detected, the sheet size of the sheet is predicted based on the detection result of the second detection unit.
The sheet conveying apparatus according to claim 1. The predicting unit is configured such that the sheet is placed on the sheet stacking table, the presence or absence of the sheet is not detected by the second detection unit, and the second detection unit within a predetermined time after conveying the sheet. If the presence or absence of the sheet is not detected, predict the sheet size of the sheet based on the detection result of the first detection means;
The sheet conveying apparatus according to claim 1. The predetermined time is D / V + α.
The sheet conveying apparatus according to claim 2, wherein the sheet conveying apparatus is provided.
Here, the distance in the conveyance direction between the sheet trailing edge of the maximum length of the sheet and the second detection unit is D, the sheet conveyance speed is V, and α is a preset time. A third detection unit that detects a sheet width that is a length in a direction orthogonal to a conveyance direction of the sheet placed on the sheet stacking table;
The prediction means predicts the sheet size of the sheet from the detection results of the second detection means and the third detection means;
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. A fourth detection unit configured to detect a length related to a conveyance direction of the sheet conveyed downstream of the first detection unit in the conveyance direction of the sheet;
The predicting means predicts the sheet size of the sheet from the detection results of the first detecting means and the third detecting means when the trailing edge of the sheet is detected by the fourth detecting means;
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. An imaging member for reading an image of the sheet;
The sheet conveying apparatus according to any one of claims 1 to 6, wherein the imaging member conveys the sheet to a reading position for reading the sheet.
An image reading apparatus. An image reading apparatus according to claim 7 for reading an image on a sheet;
An image recording device for recording an image read by the image reading device on a recording medium,
An image forming apparatus.

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