Sheet conveying device and image forming apparatus equipped with same

Abstract

To provide a sheet conveyance device which can prevent skew correction of a resist roller pair from being performed depending on a use state of a user, and an image formation apparatus having the same.SOLUTION: A sheet conveyance device (200) in which a plurality of resist roller pairs 233-233 (2331, 2332) are provided at an interval in the conveyance direction H in a sheet conveyance path 231 has: a non-resist skew correction mode MDN which does not perform skew correction on all the plurality of resist roller pairs 233-233 (2331, 2332); and resist skew correction modes MD (MD1, MD2) which perform skew correction on one or two or more resist roller pairs (2331 or 2332) of the plurality of resist roller pairs 233-233 (2331, 2332), and performs the non-resist skew correction mode MDN and the resist skew correction modes MD (MD1, MD2) according to the setting mode set by a user.SELECTED DRAWING: Figure 7B

Description

[Technical field]

[0001] The present invention relates to a sheet transport device and an image forming apparatus including the same, such as a copying machine, a multifunction machine, a printer, or a facsimile machine. [Background technology]

[0002] 2. Description of the Related Art There is a sheet conveying device in which a plurality of registration roller pairs are provided at intervals to correct skew of a sheet conveyed along a sheet conveying path (see, for example, Patent Documents 1 and 2).

[0003] In detail, Patent Document 1 describes a configuration in which, when the amount of skew is below a predetermined value, the sheet skew is corrected using either a first conveying means (first registration roller pair) or a second conveying means (second registration roller pair).

[0004] Patent document 2 also describes a configuration for selecting either a first control mode in which skew correction is performed on the sheet using a first roller pair (first registration roller pair) or a second control mode in which skew correction is performed on the sheet using the first roller pair (first registration roller pair) and then using a second roller pair (second registration roller pair). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-54747 A [Patent Document 2] JP 2009-107782 A Summary of the Invention [Problem to be solved by the invention]

[0006] Depending on the usage situation, for example, in a quiet environment where the rotation start sound (clutch sound) of the registration roller pair is unpleasant to the user, the user may not want to correct the skew of the registration roller pair.

[0007] In this regard, the configurations described in Patent Documents 1 and 2 are not configured to prevent skew correction of the pair of registration rollers depending on the usage conditions of the user.

[0008] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a sheet conveying device capable of preventing skew correction of a pair of registration rollers depending on the usage conditions of a user, and an image forming apparatus including the same. [Means for solving the problem]

[0009] In order to solve the above problems, a sheet conveying device according to the present invention is Transportation Transported to the route Rusi A plurality of registration roller pairs are provided to correct the skew of the sheet. , in the conveying direction in which the sheet is conveyed The sheet conveying device has a non-registration skew correction mode in which the skew correction is not performed by any of the plurality of registration roller pairs, and a registration skew correction mode in which the skew correction is performed by one or more registration roller pairs among the plurality of registration roller pairs, and performs the non-registration skew correction mode or the registration skew correction mode according to a setting mode set by a user. the registration skew correction mode includes a first registration skew correction mode in which the skew correction is performed by one or more but less than the plurality of registration roller pairs among the plurality of registration roller pairs, and a second registration skew correction mode in which the skew correction is performed by all of the plurality of registration roller pairs, and an image quality priority mode in which image quality is prioritized is selectable as the setting mode, and when the image quality priority mode is selected, the first registration skew correction mode or the second registration skew correction mode is performed. The present invention also relates to an image forming apparatus including the sheet conveying device according to the present invention. Effect of the Invention

[0010] According to the present invention, it is possible to avoid performing skew correction of the pair of registration rollers depending on the usage conditions of the user. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus including a document feeder according to an embodiment of the present invention. [Diagram 2] 1 is a perspective view showing a document feeder according to an embodiment of the present invention; [Diagram 3]2 is an enlarged cross-sectional view showing an original transport section of the original feeder; FIG. [Figure 4] 2 is a schematic block diagram showing a control configuration for controlling the operation of the document feeder; FIG. [Diagram 5] 2 is a schematic side view of a document transport unit in the document feeder; FIG. [Figure 6A] 1A to 1C are plan views showing a document transport section in the document feeder in a time-series manner, illustrating a state in which a minimum-sized document is being pushed into the first registration roller pair whose rotation is stopped. [Figure 6B] 1A to 1C are plan views showing a document transport section in a document feeder in a time sequence, illustrating a state in which a document larger than the minimum size is being pushed into the first registration roller pair whose rotation is stopped. [Figure 6C] 10A to 10C are plan views showing the document transport section of the document feeder in a time series manner, illustrating a state in which a document larger than the minimum size is being pushed into the second registration roller pair that is stopped from rotating. [Figure 7A] FIG. 4 is a plan view showing an example of a first selection screen of the display unit. [Figure 7B] 11 is a table showing an example of a combination of a non-resist skew correction mode, a first resist skew correction mode, and a second resist skew correction mode performed according to a setting mode. [Figure 8A] FIG. 13 is a plan view showing a first setting screen for setting any one of a non-resist skew correction mode, a first resist skew correction mode, and a second resist skew correction mode for each setting mode, and shows an initial setting state of a normal mode. [Figure 8B] 8B is a plan view showing a setting example in which the normal mode shown in FIG. 8A is changed from a first registration skew correction mode of the plain paper mode to a second registration skew correction mode. FIG. [Figure 9A] 11 is a plan view showing an example of a second selection screen of the display unit. FIG. [Figure 9B] 11 is a table showing an example of a combination of a non-resist skew correction mode and a first resist skew correction mode performed according to a set mode, together with a normal mode. [Figure 10A]FIG. 13 is a plan view showing a second setting screen for setting the non-resist skew correction mode or the first-resist skew correction mode for each setting mode, and shows an initial setting state of the quietness priority mode. [Figure 10B] 10B is a plan view showing a setting example in which the silent mode shown in FIG. 10A is changed from the non-resist skew correction mode of the thin paper mode to a first resist skew correction mode. FIG. [Figure 11A] FIG. 11 is a plan view showing an example of a third selection screen of the display unit. [Figure 11B] 11 is a table showing an example of a combination of a first resist skew correction mode and a second resist skew correction mode performed according to a setting mode, together with a normal mode and a quietness priority mode. [Figure 12A] FIG. 13 is a plan view showing a third setting screen for setting a first registration skew correction mode or a second registration skew correction mode for each setting mode, and shows an initial setting state of the image quality priority mode. [Figure 12B] 12B is a plan view showing a setting example in which the image quality priority mode shown in FIG. 12A is changed from the second registration skew correction mode in the thick paper mode to the first registration skew correction mode. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of the components are also the same. Therefore, detailed description thereof will not be repeated.

[0013] [Image forming device] Fig. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 100 including a document feeder 200 according to the present embodiment. In Fig. 1, the letter X indicates the horizontal direction (left-right direction), the letter Y indicates the depth direction (front-back direction), and the letter Z indicates the up-down direction (height direction).

[0014] The image forming apparatus 100 is a multifunction machine having a copy function, a scanner function, a facsimile function, and a printer function, and transmits to the outside an image of an original G (an example of a sheet) read by an image reading device 102. The image forming apparatus 100 also forms an image of the original G read by the image reading device 102 or an image received from the outside on paper (recording material) in color or monochrome. Note that the image forming apparatus 100 may form a monochrome image.

[0015] The image reading device 102 includes a document feeder 200 (an example of a sheet conveying device). The document feeder 200 is provided above the image reading unit 130 and is supported so as to be freely opened and closed relative to the image reading unit 130. The document feeder 200 sequentially conveys one or more documents G one by one. The image reading device 102 reads the documents G conveyed one by one by the document feeder 200 from among one or more documents. The image reading device 102 includes a document placement table 130a (document table) on which the documents G are placed, and a placed document reading function that reads the documents G placed on the document placement table 130a. When the document feeder 200 is opened, the image forming device 100 opens the document placement table 130a above the image reading unit 130, allowing the documents G to be placed manually. Further, the document feeding device 200 includes a document placement tray 210 on which the document G is placed, and a document discharge tray 250 on which the document G discharged to the outside is stacked. The image reading device 102 includes a transported document reading function for reading the document G transported by the document feeding device 200. The document feeding device 200 transports the document G placed on the document placement tray 210 onto the document reading section 130b in the image reading section 130. The image reading section 130 scans the scanning optical system 130c to read the document G placed on the document placement table 130a, or reads the document G transported by the document feeding device 200, and generates image data.

[0016] The image forming apparatus 100 includes an image forming unit 110. The image forming unit 110 includes an optical scanning device 1, a developing device 2, a photoconductor drum 3, a drum cleaning device 4, a charger 5, an intermediate transfer belt 7, a fixing device 12, a paper transport path S, a paper feed cassette 18, and a paper discharge tray 141 (internal discharge tray).

[0017] The image forming unit 110 handles image data corresponding to color images using the colors black (K), cyan (C), magenta (M), and yellow (Y), or monochrome images using a single color (e.g., black). The image transfer unit 50 of the image forming apparatus 100 is provided with four developing devices 2, four photoconductor drums 3, four drum cleaning devices 4, and four chargers 5 for forming four types of toner images, which correspond to black, cyan, magenta, and yellow, respectively, to form four image stations Pa, Pb, Pc, and Pd.

[0018] The optical scanning device 1 exposes the surface of the photoreceptor drum 3 to light to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photoreceptor drum 3 to form a toner image on the surface of the photoreceptor drum 3. The drum cleaning device 4 removes and collects residual toner on the surface of the photoreceptor drum 3. The charger 5 uniformly charges the surface of the photoreceptor drum 3 to a predetermined potential. Through the series of operations described above, a toner image of each color is formed on the surface of each photoreceptor drum 3.

[0019] An intermediate transfer roller 6 is disposed above the photosensitive drum 3 with an intermediate transfer belt 7 therebetween. The intermediate transfer belt 7 is stretched around a transfer drive roller 7a and a transfer driven roller 7b, and moves in a circular motion in the direction of arrow C. In the image forming apparatus 100, residual toner is removed and collected by a belt cleaning device 9, and the toner images of each color formed on the surface of each photosensitive drum 3 are sequentially transferred and superimposed to form a color toner image on the surface of the intermediate transfer belt 7.

[0020] A nip area is formed between the transfer roller 11a of the secondary transfer unit 11 and the intermediate transfer belt 7, and the paper conveyed through the paper conveying path S is sandwiched in the nip area and conveyed. When the paper passes through the nip area, the toner image on the surface of the intermediate transfer belt 7 is transferred to the paper, and the paper is conveyed to the fixing device 12.

[0021] The fixing device 12 includes a fixing roller 12a and a pressure roller 12b that rotate while sandwiching the paper. The fixing device 12 sandwiches the paper, on which the toner image has been transferred, between the fixing roller 12a and the pressure roller 12b and applies heat and pressure to fix the toner image to the paper.

[0022] The paper feed cassette 18 is a cassette for storing paper used for image formation, and is provided below the optical scanning device 1. The paper is pulled out from the paper feed cassette 18 by a pick-up roller 16 (pickup roller) and conveyed to the paper conveying path S. The paper conveyed to the paper conveying path S passes through the secondary transfer unit 11 and the fixing device 12, is conveyed to the discharge roller pair 17, and is discharged to the paper discharge tray 141. The paper conveying path S is provided with the conveying roller pair 13, the registration roller pair 14, and the discharge roller pair 17. The conveying roller pair 13 promotes the conveyance of the paper. The registration roller pair 14 stops the paper temporarily and aligns the leading edge of the paper. The registration roller pair 14 conveys the stopped paper in accordance with the toner image on the intermediate transfer belt 7. The toner image on the intermediate transfer belt 7 is transferred to the paper in the nip area between the intermediate transfer belt 7 and the transfer roller 11a. In addition, in FIG. 1, one sheet feed cassette 18 is provided, but the present invention is not limited to this, and a configuration in which a plurality of sheet feed cassettes 18 are provided may be used.

[0023] When forming an image on the back side of the paper in addition to the front side, the image forming apparatus 100 transports the paper in the reverse direction from the discharge roller pair 17 to the paper inversion path Sr. The image forming apparatus 100 inverts the paper transported in the reverse direction and guides it again to the registration roller pair 14. The image forming apparatus 100 also forms an image on the back side of the paper guided to the registration roller pair 14 in the same manner as on the front side, and discharges the paper to the paper discharge tray 141.

[0024] The image reading unit 130 is provided on the upper surface of the image forming apparatus main body 101. On the image reading unit 130, a document feeder 200 is attached.

[0025] [Document feeder] FIG. 2 is a perspective view showing the document feeder 200 according to the present embodiment. FIG. 3 is an enlarged cross-sectional view showing the document transport section 230 in the document feeder 200. FIG. 4 is a schematic block diagram showing a control configuration for controlling the operation of the document feeder 200. FIG. 5 is a schematic side view of the document transport section 230 in the document feeder 200. Also, FIGS. 6A to 6C are plan views showing the document transport section 230 in the document feeder 200 in a time series manner. FIG. 6A shows a state in which a document G of a minimum size (in this example, business card vertical size) is pushed into the first registration roller pair 2331 whose rotation is stopped. FIGS. 6B and 6C show a state in which a document G of a size larger than the minimum size (in the illustrated example, A4 horizontal size) is pushed into the first registration roller pair 2331 whose rotation is stopped and the second registration roller pair 2332 whose rotation is stopped, respectively.

[0026] The document feeder 200 includes a document placement tray 210, a document supply section 220, a document transport section 230, a document discharge section 240, a document discharge tray 250, a control section 260, a transport drive section 270, and a transport drive transmission mechanism 280. The document placement tray 210 places the document G. The document supply section 220 supplies the document G placed on the document placement tray 210 one by one to the document transport section 230. The document transport section 230 transports the document G supplied by the document supply section 220 at a center reference in a width direction W perpendicular to the transport direction H. The document discharge section 240 discharges the document G transported by the document transport section 230. The document discharge section 240 includes a discharge roller pair 241. The document discharge tray 250 stacks the document G discharged by the document discharge section 240. In the document feeder 200, a document placement tray 210 and a document discharge tray 250 are disposed so as to overlap each other in the vertical direction.

[0027] In detail, the document transport section 230 includes a pair of transport guides 232 (232a, 232b) that form the sheet transport path 231, a plurality of (two in this example) registration roller pairs 233-233 (2331, 2332), a pre-reading transport roller pair 234, a post-reading transport roller pair 235, and a pre-discharge transport roller pair 236. The plurality of registration roller pairs 233-233 (2331, 2332), the pre-reading transport roller pair 234, the post-reading transport roller pair 235, and the pre-discharge transport roller pair 236 are disposed in order along the sheet transport path 231.

[0028] The document supply unit 220 includes a pick-up roller 221 (pickup roller), a supply roller 222 (paper feed roller), a separation member (separation roller or separation pad (separation roller 223 in this example)), and a supply drive transmission mechanism 224.

[0029] The pickup roller 221 picks up the topmost document G among the documents G stacked on the document placement tray 210. The supply roller 222 and the separation roller 223 separate and transport the documents G picked up by the pickup roller 221 one by one. The supply roller 222 transports the documents G picked up by the pickup roller 221 together with the separation roller 223 one by one toward a pair of transport guides 232. The separation roller 223 is disposed opposite the supply roller 222. The separation roller 223 can regulate the transport of the second and subsequent documents G from the top of the documents G stacked on the document placement tray 210 in the transport direction H, and can allow the transport of the bottom document G (the last document G) in the transport direction H. The supply drive transmission mechanism 224 is composed of a gear train or a pulley and a belt, and transmits the rotational drive force sent to the supply roller 222 to the pickup roller 221. The pick-up roller 221, the supply roller 222, and the separation roller 223 are located at the center in the width direction W (see FIGS. 6A to 6C). This allows the document G to be picked up and supplied based on the center in the width direction W. The document supply unit 220 is a conventionally known device, and other detailed configurations will not be described.

[0030] The pair of conveying guides 232 form a sheet conveying path 231 between the document supply unit 220 and the document discharge unit 240. The sheet conveying path 231 is formed so as to convey the document G in a substantially horizontal direction, make a downward U-turn, and then convey the document G in an obliquely upward direction. The sheet conveying path 231 has a reading position R (see FIGS. 3 and 5) at the bottom where an image of the document G is read.

[0031] In this example, the plurality of registration roller pairs 233-233 are composed of a first registration roller pair 2331 and a second registration roller pair 2332. The first registration roller pair 2331, the second registration roller pair 2332, the pre-reading conveying roller pair 234, the post-reading conveying roller pair 235, and the pre-discharge conveying roller pair 236 are provided in this order from the supply roller 222 toward the downstream side in the conveying direction H along the sheet conveying path 231. A reading position R is provided between the pre-reading conveying roller pair 234 and the post-reading conveying roller pair 235. The pre-discharge conveying roller pair 236 is provided closest to the discharge roller pair 241 on the upstream side in the conveying direction H than the discharge roller pair 241.

[0032] The first registration roller pair 2331, the second registration roller pair 2332, the pre-reading transport roller pair 234, the post-reading transport roller pair 235, and the pre-discharge transport roller pair 236 are each composed of driving rollers 2331a, 2332a, 234a to 236a and driven rollers 2331b, 2332b, 234b to 236b. The discharge roller pair 241 is composed of a driving roller 241a and a driven roller 241b.

[0033] The transport driver 270 (brushless DC motor) (see FIG. 4) is electrically connected to an output system of the control unit 260. This allows the control unit 260 to drive the transport driver 270 at a predetermined timing. The transport drive transmission mechanism 280 transmits the rotational driving force from the transport driver 270 to the supply roller 222 and the drive rollers 2331a, 2332a, 234a to 236a, and 241a.

[0034] The transport drive transmission mechanism 280 includes a first resist clutch 281 and a second resist clutch 282. The first resist clutch 281 and the second resist clutch 282 are provided on the drive rollers 2331a and 2332a, respectively, and are configured to selectively switch between disconnection and connection of the rotational drive force to the drive rollers 2331a and 2332a. The drive rollers 2331a and 2332a are rotated by turning on the first resist clutch 281 and the second resist clutch 282, respectively. The first resist clutch 281 and the second resist clutch 282 are electrically connected to the output system of the control unit 260. This allows the control unit 260 to turn on and off the first resist clutch 281 and the second resist clutch 282 at a predetermined timing.

[0035] The driven rollers 2331b, 2332b, 234b to 236b, and 241b are rotated by the driving rollers 2331a, 2332a, 234a to 236a, and 241a. Here, the driving rollers 2331a, 2332a, 234a to 236a, and 241a all have the same diameter (specifically, 18 mm). The driven rollers 2331b, 2332b, 236b, and 241b all have the same diameter (specifically, 18 mm). In addition, the driven rollers 234b and 235b all have the same diameter, which is smaller (10 mm) than the other driven rollers 2331b, 2332b, and 236b.

[0036] As shown in Figures 6A to 6C, the first registration roller pair 2331, the second registration roller pair 2332, the pre-reading conveying roller pair 234, the post-reading conveying roller pair 235, the pre-discharge conveying roller pair 236 and the discharge roller pair 241 have roller portions 2331c to 2331c, 2332c to 2332c, 234c to 234c, 235c to 235c, 236c to 236c, and 241c to 241c in multiple locations including a central roller portion. As shown in FIG. 6A, the smallest size document G (a vertical-sized business card in this example) is clamped and transported between roller portions 2331c, 2332c, 234c, 235c, and 236c at one central location in the first registration roller pair 2331, the second registration roller pair 2332, the pre-reading transport roller pair 234, the post-reading transport roller pair 235, and the pre-discharge transport roller pair 236, and is clamped and transported between roller portions 241c, 241c at two central locations in the discharge roller pair 241.

[0037] <Control Unit> 4, the control unit 260 performs skew correction control to correct skew (diagonal feed) of the document G. The control unit 260 has a processing unit 261 made up of a computer such as a CPU (Central Processing Unit), and a storage unit 262 including a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory). The control unit 260 may be provided in the image forming apparatus 100.

[0038] In the control unit 260, the processing unit 261 calls up a control program stored in advance in the ROM of the storage unit 262, and when the control program is loaded onto the RAM of the storage unit 262, control of the operation of various components is executed.

[0039] The image forming apparatus 100 also includes an operation display unit 150. The operation display unit 150 includes a reception unit 151 (a touch panel in this example) and a display unit 152 (a display panel in this example). The reception unit 151 is electrically connected to an input system of the control unit 260. The reception unit 151 receives input operation information by a user. The display unit 152 is electrically connected to an output system of the control unit 260. The display unit 152 displays various information on a display screen based on display data. The reception unit 151 is provided on the display unit 152. The operation display unit 150 receives touch operation information by a user on various software keys displayed on the display unit 152 at the reception unit 151.

[0040] The document feeder 200 includes a first transport detector 291, a second transport detector 292, and a third transport detector 293.

[0041] The first transport detection unit 291, the second transport detection unit 292, and the third transport detection unit 293 are all light reflection type photocouplers (transport timing sensors) that irradiate light and receive reflected light from the original G.

[0042] <First conveyor detection unit> The first transport detection unit 291 is provided a predetermined first distance d1 (see FIG. 5) upstream of the first registration roller pair 2331 in the transport direction H. The first transport detection unit 291 detects whether the document G has passed the first distance d1 upstream of the first registration roller pair 2331. The first transport detection unit 291 is electrically connected to an input system of the control unit 260.

[0043] (When skew correction is performed with the first registration roller pair) The control unit 260 conveys the document G by the supply roller 222, abuts the document G against the nip portion of the first registration roller pair 2331 that is stopped from the timing when the document G is detected by the first conveyance detection unit 291, and further conveys the document G by a predetermined first pushing amount (predetermined first pushing time) from the timing when the document G is abutted. This allows the leading edge G1 of the document G to be reliably aligned along the nip portion of the first registration roller pair 2331.

[0044] (When skew correction is not performed by the first registration roller pair) The control unit 260 causes the first registration roller pair 2331 to rotate, and conveys the document G sent from the supply roller 222 directly toward the second registration roller pair 2332 by the first registration roller pair 2331 .

[0045] <Second conveyor detection unit> The second transport detection unit 292 is provided a predetermined second distance d2 (see FIG. 5) upstream of the second registration roller pair 2332 in the transport direction H. The second transport detection unit 292 detects whether the document G has passed the second distance d2 upstream of the second registration roller pair 2332. The second transport detection unit 292 is electrically connected to an input system of the control unit 260.

[0046] (When skew correction is performed by the second registration roller pair 2332) The control unit 260 conveys the document G by the first registration roller pair 2331, abuts the document G against the nip portion of the second registration roller pair 2332 that is stopped rotating from the timing when the document G is detected by the second conveyance detection unit 292, and further conveys the document G by a predetermined second pushing amount (predetermined second pushing time) from the timing when the document G is abutted. This allows the leading edge G1 of the document G to be reliably aligned along the nip portion of the second registration roller pair 2332.

[0047] (When skew correction is not performed by the second registration roller pair 2332) The control unit 260 causes the second registration roller pair 2332 to rotate, and conveys the document G sent from the supply roller 222 directly toward the pre-scan conveying roller pair 234 by the second registration roller pair 2332 .

[0048] -When skew correction is performed by the first registration roller pair and the second registration roller pair- When performing skew correction with the first registration roller pair 2331, the control unit 260 starts the rotation of the first registration roller pair 2331 at a predetermined rotation start timing in a state in which the document G is pressed into the nip portion of the first registration roller pair 2331 while the rotation is stopped. When performing skew correction with the second registration roller pair 2332, the control unit 260 starts the rotation of the second registration roller pair 2332 at a predetermined rotation start timing in a state in which the document G is pressed into the nip portion of the second registration roller pair 2332 while the rotation is stopped.

[0049] - When skew correction is performed only on the first registration roller pair - When performing skew correction only on the first registration roller pair 2331, the control unit 260 starts rotation of the first registration roller pair 2331 at a predetermined rotation start timing in a state in which the document G is pressed into the nip portion of the first registration roller pair 2331 that is stopped from rotating. Also, the control unit 260 passes the document G directly through the second registration roller pair 2332 that is rotating.

[0050] - When skew correction is performed only by the second registration roller pair - The control unit 260 passes the document G directly through the rotating first registration roller pair 2331. In addition, the control unit 260 starts the rotation of the second registration roller pair 2332 at a predetermined rotation start timing in a state in which the document G is pressed into the nip portion of the second registration roller pair 2332 that is not rotating.

[0051] -When skew correction is not performed by the first registration roller pair and the second registration roller pair- The control unit 260 causes the document G to pass directly through the first registration roller pair 2331 which is rotating and the second registration roller pair 2332 which is rotating.

[0052] <Third transport detection unit> The third transport detection unit 293 is provided a predetermined third distance d3 (see FIG. 5) upstream of the pre-reading transport roller pair 234 in the transport direction H. The third transport detection unit 293 detects whether the document G has passed the third distance d3 upstream of the pre-reading transport roller pair 234. The third transport detection unit 293 is electrically connected to an input system of the control unit 260.

[0053] The control unit 260 rotates the pre-reading conveying roller pair 234, the post-reading conveying roller pair 235, the pre-discharge conveying roller pair 236, and the discharge roller pair 241, and causes the original G sent from the second registration roller pair 2332 to pass through the reading position R using the pre-reading conveying roller pair 234, and is then conveyed toward the original discharge tray 250 by the post-reading conveying roller pair 235, the pre-discharge conveying roller pair 236, and the discharge roller pair 241.

[0054] [About this embodiment] In this embodiment, the sheet conveying device (original feeding device 200) has multiple registration roller pairs 233-233 (2331, 2332) arranged at intervals in the conveying direction H in which the sheet (G) is conveyed, for correcting skew of the sheet (original G) conveyed to the sheet conveying path 231.

[0055] The control unit 260 has a non-registration skew correction mode MDN and a registration skew correction mode MD (MD1, MD2). The non-registration skew correction mode MDN does not perform skew correction for all of the registration roller pairs 233-233 (2331, 2332). The registration skew correction mode MD (MD1, MD2) performs skew correction using one or more registration roller pairs (2331 and / or 2332) among the registration roller pairs 233-233 (2331, 2332).

[0056] The control unit 260 performs the non-resist skew correction mode MDN or the resist skew correction mode MD (MD1, MD2) according to the setting mode set by the user.

[0057] According to this embodiment, the non-resist skew correction mode MDN or the resist skew correction mode MD (MD1, MD2) is performed depending on the setting mode set by the user, so that skew correction is not performed for all of the multiple registration roller pairs 233-233 (2331, 2332) depending on the user's usage conditions.As a result, depending on the user's usage conditions, for example, in a quiet environment where the sound of the registration roller pair 233 starting to rotate would be unpleasant to the user, skew correction can be prevented from being performed for all of the multiple registration roller pairs 233-233 (2331, 2332).

[0058] Examples of the usage conditions include the surrounding environment (for example, the installation environment, such as a quiet environment where the sound of the pair of registration rollers 233 starting to rotate would annoy the user), the type of sheet (G) (for example, the thickness of the sheet (G), such as plain paper, thick paper, or thin paper, and the size of the sheet (G), such as A4 size, B5 size, or business card size), and the image formation conditions (for example, image quality, such as high resolution). Plain paper is a paper that is within a predetermined standard thickness range (a predetermined standard basis weight range, for example, 50 g / m 2 ~100g / m 2 ) standard paper (standard paper). 2 ) is a paper with a thickness (basis weight) greater than the standard thickness (the lower limit of the standard basis weight, for example 50 g / m 2 ) refers to paper with a thickness (basis weight) smaller than that of

[0059] (Normal mode) Fig. 7A is a plan view showing an example of a first selection screen S1 of the display unit 152. Fig. 7B is a table showing an example of a combination of a non-resist skew correction mode MDN, a first resist skew correction mode MD1, and a second resist skew correction mode MD2 performed according to a setting mode.

[0060] In this example, the set modes are the plain paper mode, the thick paper mode, the thin paper mode, the mixed mode, the business card mode, and the skew correction setting mode as the reading mode. Here, the plain paper mode, the thick paper mode, the thin paper mode, and the business card mode are modes for transporting plain paper, thick paper, and thin paper, respectively. The mixed mode is a mode for transporting multiple sheets of original G of different sizes in one job.

[0061] The resist skew correction mode MD has a first resist skew correction mode MD1 and a second resist skew correction mode MD2.

[0062] As shown in Fig. 7A, the first selection screen S1 of the display unit 152 displays, in the normal mode (default mode), one of the plain paper mode, thick paper mode, thin paper mode, mixed paper mode, business card mode, and skew correction setting mode that can be selected by the user. Fig. 7A shows the state in which the plain paper mode is selected.

[0063] As shown in FIG. 7B, in the memory unit 262, in normal mode, a non-resist skew correction mode MDN, a first-resist skew correction mode MD1 or a second-resist skew correction mode MD2 is pre-stored for each set mode (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode and skew correction setting mode).

[0064] In this example, in the "normal mode" storage area of ​​the storage unit 262, the first registration skew correction mode MD1 is preset in the plain paper mode and the thick paper mode. The second registration skew correction mode MD2 is preset in the thin paper mode, the mixed mode, and the business card mode. Also, the non-registration skew correction mode MDN is preset in the skew correction setting mode.

[0065] When the reception unit 151 receives a selection operation of one of the setting modes, the control unit 260 executes a mode corresponding to the received setting mode. In this example, the plain paper mode is set, but when the reception unit 151 receives a selection operation of the skew correction setting mode, for example, the control unit 260 executes a non-resist skew correction mode MDN corresponding to the received skew correction setting mode.

[0066] First Embodiment The first registration skew correction mode MD1 performs skew correction using one or more but less than a plurality (in this example, one) of the registration roller pairs 233-233 (2331 or 2332) among the plurality of registration roller pairs 233-233 (2331, 2332). The second registration skew correction mode MD2 performs skew correction using all of the plurality of registration roller pairs 233-233 (2331, 2332).

[0067] The control unit 260 performs any one of a non-resist skew correction mode MDN, a first resist skew correction mode MD1, and a second resist skew correction mode MD2 according to the set mode (see the dashed frame α1 in FIG. 7B).

[0068] This makes it possible to avoid performing skew correction on all of the multiple (in this example, two) pairs of registration rollers 233-233 (2331, 2332) depending on the user's usage.As a result, depending on the user's usage, for example, in a quiet environment where the sound of the registration roller pair 233 starting to rotate would be unpleasant to the user, it is possible to avoid performing skew correction on all of the multiple (in this example, two) pairs of registration rollers 233-233 (2331, 2332).

[0069] In this embodiment, the sheet conveying device (200) is capable of conveying a plurality of types of sheets (G) (in this example, a plurality of thicknesses (basis weights) and / or a plurality of sizes).

[0070] Incidentally, the smaller the thickness (basis weight) of the sheet (G) and the smaller the size of the sheet (G), the more likely the sheet (G) is to skew, especially in a small size such as a business card size (the smallest size in this example).Alternatively / furthermore, when multiple originals G of different sizes are transported in one job (mixed mode), the largest size original G among the transported originals G is supported from both sides by a pair of sheet regulating members provided on both sides in the width direction W, while the smaller size original G is supported only on one side of one sheet regulating member, so the original G is more likely to skew.

[0071] In this regard, the control unit 260 allows a selection of multiple sheet type modes (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode) as setting modes depending on the type of sheet (G) on the first selection screen S1 shown in FIG. 7A (see dashed frame α2 in FIG. 7B), and when any one of the multiple sheet type modes (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode) is selected, executes the first resist skew correction mode MD1 or the second resist skew correction mode MD2.

[0072] In this way, depending on the type of sheet (G), either a first resist skew correction mode (skew correction more than once but less than multiple times, in this example, once) or a second resist skew correction mode (skew correction multiple times, in this example, twice) can be performed, thereby making it possible to change the number of times the sheet is skew corrected depending on the type of sheet (G).

[0073] As shown in Fig. 7A, in the normal mode, the first selection screen S1 of the display unit 152 displays one of the plain paper mode, thick paper mode, thin paper mode, mixed paper mode, business card mode, and skew correction setting mode selectable by the user. Fig. 7A shows the state in which the plain paper mode is selected.

[0074] In this example, when the control unit 260 receives the plain paper mode or the thick paper mode as the sheet type mode at the reception unit 151, it executes a first registration skew correction mode MD1 in which skew correction is performed once only by the first registration roller pair 2331. In addition, when the control unit 260 receives the thin paper mode, the mixed mode, or the business card mode as the sheet type mode at the reception unit 151, it executes a second registration skew correction mode MD2 in which skew correction is performed twice, that is, by the first registration roller pair 2331 and by the second registration roller pair 2332.

[0075] Incidentally, if the control unit 260 does not execute the non-registration skew correction mode MDN to correct the skew of the sheet (G) of all the registration roller pairs 233 to 233 (2331, 2332), the skew of the sheet (G) cannot be corrected as it is.

[0076] In this regard, in the present embodiment, the control unit 260 further has an image processing skew correction mode MDP (see FIG. 4) that corrects the skew of the sheet (G) by image processing as a skew correction other than the skew correction by the multiple registration roller pairs 233-233 (2331, 2332).

[0077] Then, the control unit 260 allows the selection of a skew correction setting mode in which an image processing skew correction mode MDP is executed as a setting mode on the first selection screen S1 shown in FIG. 7A (see dashed frame α3 in FIG. 7B), and when the skew correction setting mode is selected, the non-resist skew correction mode MDN is executed to not perform skew correction for all of the multiple registration roller pairs 233-233 (2331, 2332), but instead executes the image processing skew correction mode MDP (see FIG. 4).

[0078] In this way, even if the non-registration skew correction mode MDN is executed and skew correction of the sheet (G) is not performed by all of the registration roller pairs 233 to 233 (2331, 2332), skew correction of the sheet (G) can be performed.

[0079] Moreover, the skew of the sheet (G) can be easily corrected by image processing. Here, the image processing for correcting the skew of the sheet (G) is image processing that detects the leading and trailing ends of the sheet (G) and both side edges in the width direction W perpendicular to the conveying direction H of the sheet (G) based on the detection result of an image detection unit (image sensor) that detects the image of the sheet (G), and makes the shape formed by the detected leading and trailing ends and both side edges of the sheet into a right-angled quadrangle with all four corners being right angles. This image processing can be performed by a conventionally known method, and detailed explanation will be omitted here.

[0080] <Second embodiment> In the sheet conveying device (200) according to the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0081] Incidentally, a user may wish to set the number of skew corrections for sheet (G) to a desired number in various setting modes (in this example, plain paper mode, thick paper mode, thin paper mode, mixed paper mode, business card mode, and skew correction setting mode).

[0082] In this regard, in the present embodiment, the control unit 260 is capable of setting any one of the non-resist skew correction mode MDN, the first resist skew correction mode MD1, or the second resist skew correction mode MD2 for each setting mode (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode, skew correction setting mode).

[0083] 8A and 8B are plan views showing a first setting screen T1 for setting one of the non-registration skew correction mode MDN, the first registration skew correction mode MD1, and the second registration skew correction mode MD2 for each setting mode (in this example, the plain paper mode, the thick paper mode, the thin paper mode, the mixed mode, the business card mode, and the skew correction setting mode). Fig. 8A shows the initial setting state of the normal mode, and Fig. 8B shows a setting example in which the first registration skew correction mode MD1 of the plain paper mode is changed to the second registration skew correction mode MD2 in the normal mode shown in Fig. 8A.

[0084] In this way, the number of skew corrections for sheet (G) can be changed to the desired number in various setting modes (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode, and skew correction setting mode).

[0085] <Third embodiment> In the sheet conveying device (200) according to the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

[0086] (Silent Priority Mode) Fig. 9A is a plan view showing an example of the second selection screen S2 of the display unit 152. Fig. 9B is a table showing an example of a combination of the non-resist skew correction mode MDN and the first resist skew correction mode MD1 performed according to the setting mode, together with the normal mode.

[0087] In a quiet environment where the rotation start sound of the registration roller pair 233 (especially when transporting cardboard) is unpleasant to the user, the user may want to reduce the number of times skew correction is performed by the multiple registration roller pairs 233-233 (2331, 2332).

[0088] In this regard, in the present embodiment, the control unit 260 allows a quietness priority mode that prioritizes quietness to be selected as a setting mode (operation mode) on the second selection screen S2 shown in FIG. 9A (see dashed frame α4 in FIG. 9B), and when the quietness priority mode is selected, the non-resist skew correction mode MDN or the first resist skew correction mode MD1 is performed.

[0089] This makes it possible to reduce or eliminate the number of times skew correction is performed by the multiple registration roller pairs 233-233 (2331, 2332) even in a quiet environment where the rotation start sound of the registration roller pair 233 would be unpleasant to a user.

[0090] As shown in Fig. 9A, in the quiet mode, the second selection screen S2 of the display unit 152 displays one of the plain paper mode, the thick paper mode, the thin paper mode, the mixed paper mode, the business card mode, and the skew correction setting mode that can be selected by the user. Fig. 9A shows the state in which the thick paper mode is selected.

[0091] As shown in FIG. 9B, in the memory unit 262, in the quiet priority mode, a non-resist skew correction mode MDN or a first-resist skew correction mode MD1 is pre-stored for each set mode (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode, and skew correction setting mode).

[0092] In this example, in the storage area for the "quiet mode" in the storage unit 262, the non-registered skew correction mode MDN is preset in the plain paper mode, the thick paper mode, the thin paper mode, and the skew correction setting mode. Also, the first-registered skew correction mode MD1 is preset in the mixed mode and the business card mode.

[0093] When the control unit 260 receives a selection operation of one of the set modes (e.g., cardboard mode) at the receiving unit 151 (see FIG. 9A), the control unit 260 executes a mode (e.g., non-resist skew correction mode MDN) corresponding to the received set mode (e.g., cardboard mode).

[0094] 10A and 10B are plan views showing a second setting screen T2 for setting the non-resist skew correction mode MDN or the first-resist skew correction mode MD1 for each setting mode (in this example, the plain paper mode, the thick paper mode, the thin paper mode, the mixed mode, the business card mode, and the skew correction setting mode). Fig. 10A shows the initial setting state of the quietness priority mode, and Fig. 10B shows a setting example in which the non-resist skew correction mode MDN of the thin paper mode is changed to the first-resist skew correction mode MD1 in the quietness priority mode shown in Fig. 10A.

[0095] In this way, the number of skew corrections for sheet (G) can be changed to the desired number in various setting modes (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode, and skew correction setting mode).

[0096] (Image quality priority mode) Fig. 11A is a plan view showing an example of a third selection screen S3 of the display unit 152. Fig. 11B is a table showing an example of a combination of the first registration skew correction mode MD1 and the second registration skew correction mode MD2 performed according to the setting mode, together with the normal mode and the quietness priority mode.

[0097] However, there are cases where a user wants to prioritize image quality and increase the number of times skew correction is performed by the multiple registration roller pairs 233-233 (2331, 2332). In addition, in the image processing skew correction mode, skew correction is performed by image processing, so image quality is likely to deteriorate. This is particularly noticeable when image processing is performed on a binary image (for example, when a diagonal line becomes stepped by image processing).

[0098] In this regard, in the present embodiment, the control unit 260 allows an image quality priority mode that prioritizes image quality to be selected as a setting mode (operation mode) on the third selection screen S3 shown in FIG. 11A (see dashed frame α5 in FIG. 11B), and when the image quality priority mode is selected, executes the first resist skew correction mode MD1 or the second resist skew correction mode MD2 (for example, the second resist skew correction mode MD2).

[0099] In this way, the number of times that the skew correction is performed by the registration roller pairs 233 to 233 (2331, 2332) can be increased, with a priority given to image quality. In addition, since the skew correction is performed by the registration roller pair 233, deterioration of image quality can be avoided.

[0100] 11A, in the image quality priority mode, the third selection screen S3 of the display unit 152 displays one of the plain paper mode, the thick paper mode, the thin paper mode, the mixed paper mode, the business card mode, and the skew correction setting mode that can be selected by the user. FIG. 11A shows the state in which the skew correction setting mode is selected.

[0101] As shown in FIG. 11B, in the memory unit 262, in the image quality priority mode, a first resist skew correction mode MD1 or a second resist skew correction mode MD2 (e.g., the second resist skew correction mode MD2) is pre-stored for each setting mode (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode, and skew correction setting mode).

[0102] In this example, in the memory area of ​​the memory unit 262 for the "image quality priority mode," the second registration skew correction mode MD2 is preset in the plain paper mode, thick paper mode, thin paper mode, mixed paper mode, business card mode, and skew correction setting mode.

[0103] When the control unit 260 receives a selection operation of one of the setting modes (e.g., the skew correction setting mode) at the receiving unit 151 (see FIG. 11A), the control unit 260 executes a mode (e.g., the second resist skew correction mode MD2) corresponding to the received setting mode (e.g., the skew correction setting mode).

[0104] 12A and 12B are plan views showing a third setting screen T3 for setting the first registration skew correction mode MD1 or the second registration skew correction mode MD2 for each setting mode (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode, and skew correction setting mode). Fig. 12A shows the initial setting state of the image quality priority mode, and Fig. 12B shows a setting example in which the second registration skew correction mode MD2 of the thick paper mode is changed to the first registration skew correction mode MD1 in the image quality priority mode shown in Fig. 12A.

[0105] In this way, the number of skew corrections for sheet (G) can be changed to the desired number in various setting modes (in this example, plain paper mode, thick paper mode, thin paper mode, mixed mode, business card mode, and skew correction setting mode).

[0106] <Fourth embodiment> In the present embodiment, as shown in Figures 3, 5, and 6A to 6C, the sheet conveying device (200) includes a supply roller 222. The supply roller 222 is provided closest to the multiple registration roller pairs 233 on the upstream side in the conveying direction H of the sheet (G) relative to the multiple registration roller pairs 233.

[0107] 6A to 6C, the supply roller 222 is usually provided at one location in the center in the width direction W of the sheet (G). When the registration roller pair provided downstream of the supply roller 222 in the conveying direction H of the sheet (G) is the registration roller pair (first registration roller pair 2331) closest to the supply roller 222, the sheet (G) pushed into the registration roller pair (2331) closest to the supply roller 222 whose rotation is stopped (see FIGS. 6A and 6B) is sandwiched only by the supply roller 222 provided at one location in the center in the width direction W of the sheet (G). Therefore, the sheet (G) pushed into the registration roller pair (2331) closest to the supply roller 222 whose rotation is stopped is not restricted by anything other than the supply roller 222, and the skew correction can be performed to a greater extent. In contrast, a sheet (G) pushed into the downstream registration roller pair (second registration roller pair 2332) that is stopped and located downstream of the registration roller pair (2331) closest to the supply roller 222 (see FIG. 6C) is sandwiched between roller portions (2331c-2331c) provided at multiple locations on the roller pair (first registration roller pair 2331) upstream of the downstream registration roller pair (2332) in the width direction W of the sheet (G) depending on the size of the sheet (G) (in this example, for sizes larger than the minimum size (see FIG. 6A)). Therefore, the sheet (G) pushed into the downstream registration roller pair (2332) that is stopped is constrained by the multiple roller portions (2331c-2331c) of the upstream roller pair (2331), and accordingly the skew correction cannot be performed to a large extent.

[0108] Furthermore, when the sheet (G) is skewed, the more distant the sheet (G) is from the supply roller 222, the greater the lateral deviation in the width direction W of the sheet (G).

[0109] In this regard, in the present embodiment, the registration roller pair (2331, 2332) that performs skew correction in the registration skew correction mode MD is the registration roller pair (2331) that is closest to the supply roller 222 downstream in the conveying direction H of the sheet (G) among the multiple registration roller pairs 233-233.

[0110] In this way, the sheet (G) pushed into the pair of registration rollers (2331) closest to the supply roller 222 that is stopped from rotating is not constrained by anything other than the supply roller 222 located at one location in the center in the width direction W, so that skew correction can be performed to a greater extent and lateral deviation in the width direction W can be kept small.

[0111] <Fifth embodiment> In the present embodiment, in the second registration skew correction mode MD2, a first pushing amount (first pushing time) of the sheet (G) to the registration roller pair (2331) closest to the supply roller 222 among the multiple registration roller pairs 233-233 is larger than a second pushing amount (second pushing time) of the sheet (G) to the registration roller pair (2332) other than the registration roller pair (2331) closest to the supply roller 222. Here, the first pushing amount (first pushing time) and the second pushing amount (second pushing time) are the transport amount (transport time) of the sheet (G) from when the sheet hits the registration roller pair to when the sheet (G) is stopped, in other words, the deflection amount of the leading end of the sheet (G).

[0112] In this way, the skew can be largely corrected by the registration roller pair (2331) closest to the supply roller 222, and the skew can be corrected to a smaller extent by the registration roller pair (2332) other than the registration roller pair (2331) closest to the supply roller 222 than the skew correction by the registration roller pair (2331) closest to the supply roller 222. As a result, first, the large skew can be corrected by the registration roller pair (2331) closest to the supply roller 222, and then the small skew can be corrected with high accuracy by the registration roller pair (2332) other than the registration roller pair (2331) closest to the supply roller 222.

[0113] Sixth embodiment In this example, the sheet transport device is an original feeder 200 that reads an original G, which is a sheet, at a predetermined reading position R in a sheet transport path 231. The sheet transport device (200) includes a supply roller 222 provided closest to the multiple registration roller pairs 233-233 on the upstream side in the transport direction H of the original G relative to the multiple registration roller pairs 233-233.

[0114] Incidentally, it is conceivable to provide the registration roller pair 233 closest to the reading position R on the upstream side in the transport direction H of the document G relative to the reading position R, but in this case, the space between the registration roller pair and the reading position R is limited in order to read the smallest size document G (in this example, a business card), making it difficult to provide a registration clutch for the registration roller pair. Also, since the roller pair provided closest to the reading position R on the upstream side in the transport direction H of the document G relative to the reading position R is involved in the reading operation of the image of the document G, the on-off vibration of the registration clutch is likely to affect the read image of the document G.

[0115] In this regard, the sheet conveying device (200) includes a pre-reading conveying roller pair 234 provided closest to the reading position R on the upstream side in the conveying direction H of the document G from the reading position R. The multiple registration roller pairs 233-233 are two registration roller pairs (2331, 2332) including a first registration roller pair 2331 provided upstream of the pre-reading conveying roller pair 234 in the conveying direction H of the document G, and a second registration roller pair 2332 provided downstream of the first registration roller pair 2331 in the conveying direction H of the document G and upstream of the pre-reading conveying roller pair 234 (in this example, closest to the upstream pre-reading conveying roller pair 234).

[0116] This eliminates the need to provide a registration clutch to the pre-scanning conveying roller pair 234, and makes it possible to narrow the space between the pre-scanning conveying roller pair 234 and the reading position R in order to read a minimum-sized document G (particularly a business card). In addition, since the second registration roller pair 2332 is provided upstream of the pre-scanning conveying roller pair 234, it is possible to make it difficult for the on / off vibration of the registration clutch of the second registration roller pair 2332 to affect the read image of the document G.

[0117] In the non-registration skew correction mode MDN, the control unit 260 does not perform skew correction using either the first registration roller pair 2331 or the second registration roller pair 2332. In the first registration skew correction mode MD1, the control unit 260 performs skew correction using the first registration roller pair 2331. In the second registration skew correction mode MD2, the control unit 260 performs skew correction using both the first registration roller pair 2331 and the second registration roller pair 2332.

[0118] This makes it possible to avoid performing skew correction for both registration roller pairs (2331, 2332) depending on the user's usage conditions, for example, in a quiet environment where the sound of the registration roller pair 233 starting to rotate would be unpleasant to the user.

[0119] (Other embodiments) In the embodiment described above, the number of the registration roller pairs 233 is two, but it may be three or more. Also, the sheet is the document G, but it may be a recording paper. In this case, a plurality of registration roller pairs are provided in the image forming apparatus main body 101.

[0120] The present invention is not limited to the above-described embodiment, but can be embodied in various other forms. Therefore, the embodiment is merely illustrative in all respects and should not be interpreted as being restrictive. The scope of the present invention is defined by the claims, and is not limited in any way by the text of the specification. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention. [Explanation of symbols]

[0121] 100 Image forming device 150 Operation display section 151 Reception 152 Display section 200 Document feeder (an example of a sheet transport device) 210 Document tray 220 Manuscript Supply Unit 221 Pick-up roller 222 Supply roller 223 Separation roller 224 Supply drive transmission mechanism 230 Document transport section 231 Sheet transport path 232 Transport guide 233 Registration roller pair 2331 First registration roller pair 2332 Second registration roller pair 234 Pre-reading conveying roller pair 235 Post-read conveying roller pair 236 Pre-discharge conveying roller pair 240 Document output section 241 Discharge roller pair 250 Document output tray 260 Control Unit 261 Processing section 262 Storage section 270 Conveyor drive unit 280 Transport drive transmission mechanism 281 First Resist Clutch 282 Second Resist Clutch 291 First conveyor detection unit 292 Second conveyor detection unit 293 3rd Transport Detection Unit G Manuscript G1 Tip H Transport direction MD registration skew correction mode MD1 First resist skew correction mode MD2 Second registration skew correction mode MDN non-resist skew correction mode MDP image processing deskew mode R Reading position S1 First selection screen S2 Second selection screen S3 3rd selection screen T1 First setting screen T2 2nd setting screen T3 3rd setting screen W Width direction d1 First distance d2 2nd distance d3 Third distance

Claims

1. A sheet conveying device including a plurality of registration roller pairs for correcting skew of a sheet conveyed to a sheet conveying path, the registration roller pairs being disposed at intervals in a conveying direction of the sheet, a non-resist skew correction mode in which the skew correction is not performed on any of the plurality of registration roller pairs; a registration skew correction mode in which the skew correction is performed by one or more registration roller pairs among the plurality of registration roller pairs; having According to the setting mode set by the user, the non-resist skew correction mode or the resist skew correction mode is performed. the registration skew correction mode includes a first registration skew correction mode in which the skew correction is performed by one or more but less than the plurality of registration roller pairs among the plurality of registration roller pairs, and a second registration skew correction mode in which the skew correction is performed by all of the plurality of registration roller pairs, As the setting mode, a picture quality priority mode in which picture quality is prioritized can be selected, a first resist skew correction mode or a second resist skew correction mode, when the image quality priority mode is selected, said sheet conveying apparatus performing said first resist skew correction mode or said second resist skew correction mode.

2. 2. The sheet conveying device according to claim 1, a non-resist skew correction mode, a first resist skew correction mode, or a second resist skew correction mode, in accordance with the set mode;

3. 3. The sheet conveying device according to claim 2, A plurality of types of sheets can be conveyed as the sheet, As the setting mode, a plurality of sheet type modes can be selected according to the type of the sheet, a first skew correction mode for correcting a skew of a resist sheet when the first skew correction mode is selected from among the plurality of sheet type modes;

4. The sheet conveying device according to any one of claims 1 to 3, The sheet skew correction method further includes an image processing skew correction mode in which the sheet skew is corrected by image processing as a skew correction other than the skew correction by the plurality of registration roller pairs, A skew correction setting mode for executing the image processing skew correction mode can be selected as the setting mode, a non-registration skew correction mode for executing the non-registration skew correction mode and not executing the skew correction for all of the plurality of registration roller pairs, and instead, executing the image processing skew correction mode when the skew correction setting mode is selected.

5. The sheet conveying device according to any one of claims 1 to 4, a non-resist skew correction mode, a first resist skew correction mode, or a second resist skew correction mode, each of the set modes being able to be set to any one of the non-resist skew correction mode, the first resist skew correction mode, and the second resist skew correction mode.

6. The sheet conveying device according to any one of claims 1 to 5, A quietness priority mode in which quietness is prioritized can be selected as the setting mode, a non-registration skew correction mode or a first registration skew correction mode is performed when the quiet mode is selected.

7. The sheet conveying device according to any one of claims 1 to 6, a supply roller provided upstream of the plurality of registration roller pairs in a conveying direction of the sheet, A sheet conveying device characterized in that the registration roller pair that performs the skew correction in the registration skew correction mode is a registration roller pair among the multiple registration roller pairs that is closest to the supply roller downstream in the conveying direction of the sheet than the supply roller.

8. The sheet conveying device according to claim 7, A sheet conveying device characterized in that a first pushing amount of the sheet toward the registration roller pair closest to the supply roller among the plurality of registration roller pairs is greater than a second pushing amount of the sheet toward the registration roller pair other than the registration roller pair closest to the supply roller.

9. The sheet conveying device according to any one of claims 1 to 8, a document feeder that reads the document, which is the sheet, at a predetermined reading position in the sheet transport path; a supply roller provided upstream of the plurality of pairs of registration rollers in a transport direction of the document, and a pair of pre-read transport rollers provided closest to the reading position on the upstream side of the reading position in the transport direction of the document, the plurality of registration roller pairs are two registration roller pairs including a first registration roller pair provided upstream of the pre-reading transport roller pair in the transport direction of the document, and a second registration roller pair provided downstream of the first registration roller pair in the transport direction of the document and upstream of the pre-reading transport roller pair, In the non-registration skew correction mode, the skew correction is not performed by either the first registration roller pair or the second registration roller pair, A sheet conveying device characterized in that the registration skew correction mode includes a first registration skew correction mode in which the skew correction is performed by the first registration roller pair, and a second registration skew correction mode in which the skew correction is performed by both the first registration roller pair and the second registration roller pair.

10. 10. An image forming apparatus comprising the sheet conveying device according to claim 1.

Images