Sheet feeding device and image forming system

Abstract

The goal is to enable feeding even sheets with high adhesion to each other, while reducing sheet skew. [Solution] The sheet feeding device comprises a sheet support section that supports a sheet bundle, a sheet feeding section that performs a feeding operation to feed the top sheet of the sheet bundle supported by the sheet support section, and an air blowing section that performs a blowing operation to blow air onto the sides of the sheet bundle supported by the sheet support section to separate the sheets. The air blowing section performs the blowing operation (S2), and after the blowing operation is stopped (S4), the sheet feeding section performs the feeding operation with the blowing operation stopped (S5).

Description

Technical Field

[0001] The present invention relates to a sheet feeding device that performs a blowing operation of blowing air to separate sheets, and an image forming system.

Background Art

[0002] For example, in image forming apparatuses such as copiers, facsimiles, printers, etc., and image forming systems equipped with an image forming apparatus, there are provided sheet feeding devices such as a feeding cassette or a feeding deck for setting a bundle of sheets to be supplied to an image forming unit that forms an image. In recent years, there has been an increasing demand to form images on various types of sheets. For example, sheets having a smooth surface property such as coated paper may be used as a recording material. When a bundle of such sheets with a smooth surface is set in a sheet feeding device, the adhesion force between the sheets is high, and it may become difficult to feed the sheets. Therefore, there has been proposed a device that blows air onto the sheet bundle to float the sheets and thereby separate the sheets (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A general control method for feeding sheets by blowing air onto a stack of sheets to separate them, as described in Patent Document 1 above, will be explained using Figure 15. As shown in Figure 15, when control for feeding sheets is started in response to a command such as the start of a print job (S101), first, air is blown onto the stack of sheets (S102). Air blowing continues until a predetermined time (e.g., 10 seconds) has elapsed (No. in S103). Subsequently, after a predetermined time has elapsed since the start of air blowing (Yes in S103), a feeding operation is performed in which sheets are fed to the image forming unit by a pickup roller or the like (S104). The feeding operation is then repeated until the required number of sheets to be fed to the image forming unit based on the print job command is reached (No. in S105), and when the required number of sheets is reached (Yes in S105), air blowing is stopped (S106) and this control is terminated (S107).

[0005] However, when feeding the sheet while blowing air onto it, as in this control system, the sheet is floating, making the edges of the sheet prone to bending. Therefore, even if the sheet's position in the width direction is restricted by, for example, a regulating plate, there is a problem that the sheet will easily become skewed if a pivoting force is generated, causing the edges of the sheet to bend.

[0006] Therefore, the present invention aims to provide a sheet feeding device and an image forming system that can feed sheets with high adhesion to each other while reducing sheet skew. [Means for solving the problem]

[0007] One aspect of the present invention is a sheet feeding device comprising: a sheet support section for supporting a sheet bundle; a sheet feeding section that contacts the uppermost sheet of the sheet bundle supported by the sheet support section and performs a feeding operation to feed the uppermost sheet; an air blowing section that performs a blowing operation to blow air onto the side surface of the sheet bundle supported by the sheet support section; and a control unit that controls the feeding operation of the sheet feeding section and the blowing operation of the air blowing section, wherein the control unit is capable of executing a feeding mode in which, when the number of sheets to be fed exceeds a predetermined number, the air blowing section performs the blowing operation, stops the blowing operation, and then, with the blowing operation stopped, the sheet feeding section performs the feeding operation to feed the predetermined number of sheets, and thereafter stops the feeding operation of the sheet feeding section, performs the blowing operation, stops the blowing operation, and then resumes the feeding operation in which the sheet feeding section feeds sheets.

[0008] One aspect of the present invention comprises a sheet support section for supporting a sheet bundle, a sheet feeding section that contacts the uppermost sheet of the sheet bundle supported by the sheet support section and performs a feeding operation to feed the uppermost sheet, an air blowing section that performs a blowing operation to blow air onto the side surface of the sheet bundle supported by the sheet support section, and a control section that controls the feeding operation of the sheet feeding section and the blowing operation of the air blowing section, wherein the control section performs the blowing operation using the air blowing section, stops the blowing operation, and then performs the blowing operation In a feeding mode in which a feeding operation is performed in which a predetermined number of sheets are fed by the sheet feeding unit while the device is stopped, if the number of sheets to be fed exceeds the predetermined number, the sheet feeding operation by the sheet feeding unit is stopped after the predetermined number of sheets have been fed, the air blowing operation is performed by the air blowing unit, and after the air blowing operation is stopped, the feeding operation is restarted in which the sheet feeding unit feeds sheets while the air blowing operation is stopped.

[0009] One aspect of the present invention comprises: a sheet support section for supporting a sheet bundle; a sheet feeding section that contacts the uppermost sheet of the sheet bundle supported by the sheet support section and performs a feeding operation to feed the uppermost sheet; an air blowing section that performs a blowing operation to blow air onto the side surface of the sheet bundle supported by the sheet support section; a sheet detection section that detects a sheet downstream of the sheet feeding section in the feeding direction; and a control section that controls the feeding operation of the sheet feeding section and the blowing operation of the air blowing section, wherein the control section performs the blowing operation using the air blowing section, stops the blowing operation, and then, with the blowing operation stopped, The sheet feeding device is capable of executing a feeding mode in which a sheet is fed by the sheet feeding unit, and the control unit, in the feeding mode, stops the feeding operation by the sheet feeding unit, performs the blowing operation by the air blowing unit, and after stopping the blowing operation, restarts the feeding operation in which the sheet is fed by the sheet feeding unit while the blowing operation is stopped.

[0010] One aspect of the present invention comprises a sheet support section for supporting a sheet bundle, a sheet feeding section that contacts the uppermost sheet of the sheet bundle supported by the sheet support section and performs a feeding operation to feed the uppermost sheet, an air blowing section that blows air onto the side surface of the sheet bundle supported by the sheet support section, and a control section that controls the feeding operation of the sheet feeding section and the blowing operation of the air blowing section, wherein the sheet feeding section has a feeding roller that contacts the uppermost sheet to feed the sheet, and a motor that drives the feeding roller, and the control section performs the blowing operation by the air blowing section and, after stopping the blowing operation... The sheet feeding device is characterized in that, while the spraying operation is stopped, it is possible to execute a feeding mode in which the sheet feeding unit feeds sheets, and in the feeding mode, if the motor torque output when the sheet feeding unit feeds sheets is greater than the set torque and the required number of sheets have not been fed, the control unit stops the feeding operation by the sheet feeding unit, performs the spraying operation by the air spraying unit, and after stopping the spraying operation, performs a feeding restart operation in which the sheet feeding unit feeds sheets while the spraying operation is stopped.

[0011] One aspect of the present invention comprises a sheet support section for supporting a sheet bundle, a sheet feeding section that contacts the uppermost sheet of the sheet bundle supported by the sheet support section and performs a feeding operation to feed the uppermost sheet, an air blowing section that performs a blowing operation to blow air onto the side surface of the sheet bundle supported by the sheet support section, and a control unit that controls the feeding operation of the sheet feeding section and the blowing operation of the air blowing section, wherein the control unit performs the blowing operation using the air blowing section, and after stopping the blowing operation, with the blowing operation stopped, the control unit controls the sheet feeding section The sheet feeding device is capable of executing a feeding mode that performs the feeding operation to feed more sheets, and the control unit, in the feeding mode, if the load generated when the sheet feeding unit feeds the sheets is greater than the set load and the required number of sheets have not been fed, stops the feeding operation by the sheet feeding unit, performs the blowing operation by the air blowing unit, and after stopping the blowing operation, performs a feeding restart operation in which the sheet feeding unit feeds the sheets while the blowing operation is stopped. [Effects of the Invention]

[0012] According to the present invention, it is possible to feed sheets even if they have high adhesion to each other, while reducing the skewness of the sheets. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows a schematic configuration of the image forming system according to the first embodiment. [Figure 2] This is a block diagram showing the control system of an image forming system according to the first embodiment. [Figure 3] This is a schematic diagram showing the configuration of the supply deck according to the first embodiment. [Figure 4] This is a schematic diagram showing the state in which an air blowing operation is performed on the supply deck according to the first embodiment. [Figure 5] This is a flowchart showing the sheet feeding control according to the first embodiment. [Figure 6] It is a graph showing the relationship between the number of sheets fed and the skew amount when feeding a sheet with sheet feeding control according to the first embodiment and when feeding a sheet while performing an air blowing operation. [Figure 7] It is a flowchart showing sheet feeding control according to the second embodiment. [Figure 8] It is a flowchart showing sheet feeding control according to the third embodiment. [Figure 9] It is a graph showing the relationship between the number of sheets fed and the feeding time to the sheet detection sensor according to the third embodiment. [Figure 10] It is a flowchart showing sheet feeding control according to the fourth embodiment. [Figure 11] It is a graph showing the relationship between the number of sheets fed and the motor torque of the feed motor according to the fourth embodiment. [Figure 12] It is a flowchart showing sheet feeding control according to the fifth embodiment. [Figure 13] It is a diagram showing a mode selection screen according to the fifth embodiment. [Figure 14] It is an explanatory diagram explaining the generation of turning force due to the positional relationship between the pickup roller and the feed roller. [Figure 15] It is a flowchart showing general sheet feeding control.

Embodiments for Carrying Out the Invention

[0014] <The First Embodiment> Hereinafter, the first embodiment of the present invention will be described in detail with reference to the drawings. First, an image forming system 600 including a feed deck 500 as a sheet feeding device according to the present invention and an image forming device 201 connected thereto will be described using FIG. 1. FIG. 1 is a diagram showing a schematic configuration of an image forming system according to the first embodiment.

[0015] [Schematic Configuration of Image Forming System] As shown in Figure 1, the image forming system 600 comprises an image forming apparatus 201 and a feed deck 500 connected to the image forming apparatus 201. The feed deck 500, which functions as a sheet feed device, is connected to the right side of the image forming apparatus 201 in Figure 1 and is configured to feed sheets S to the image forming apparatus 201.

[0016] [Outline configuration of an image forming apparatus] In Figure 1, 201 is an image forming apparatus, 201A is the main body of the image forming apparatus, and 201B is the image forming unit that forms an image on a sheet. 202 is an image reading device installed approximately horizontally above the main body 201A of the image forming apparatus, and a discharge space V for sheet discharge is formed between this image reading device 202 and the main body 201A of the image forming apparatus. An operation unit 730, consisting of a touch panel or the like capable of displaying a screen, is positioned above the main body 201A of the image forming apparatus.

[0017] The image forming unit 201B, which is an image forming means, is a 4-drum full-color system. The image forming unit 201B comprises a laser scanner 210 and four process cartridges 211Y, 211M, 211C, and 211K that form toner images of four colors: yellow (Y), magenta (M), cyan (C), and black (K). Here, each process cartridge 211 comprises a photosensitive drum 212, a charger 213 which is a charging means, and a developer 214 which is a developing means. The image forming unit 201B also comprises an intermediate transfer unit 201C and a fuser unit 201E located above the process cartridges 211. Note that 215 is a toner cartridge for supplying toner to the developer 214.

[0018] The intermediate transfer unit 201C includes an intermediate transfer belt 216 wrapped around a drive roller 216a and a tension roller 216b. A primary transfer roller 219 is provided inside the intermediate transfer belt 216, in contact with the intermediate transfer belt 216 at a position opposite the photoreceptor drum 212. The intermediate transfer belt 216 rotates in the direction of the arrow by the drive roller 216a, which is driven by a drive unit (not shown).

[0019] Then, the primary transfer roller 219 sequentially transfers the negative polarity toner images of each color on the photoreceptor drum onto the intermediate transfer belt 216. Opposite the drive roller 216a of the intermediate transfer unit 201C, a secondary transfer roller 217 is provided to transfer the color image formed on the intermediate transfer belt to the sheet P. The space between the intermediate transfer belt 216 and the secondary transfer roller 217 constitutes the secondary transfer section 201D. Furthermore, a fixing section 201E having a pressure roller 220a and a heating roller 220b is positioned above the secondary transfer roller 217. In addition, a first discharge roller pair 225a, a second discharge roller pair 225b, and a double-sided inversion section 201F are positioned in the upper left of the fixing section 201E. This double-sided inversion section 201F is provided with a reversible inversion roller pair 222 and a re-transport passage R for transporting the sheet with an image formed on one side back to the image forming section 201B.

[0020] A sheet feeding unit 230 is provided at the bottom of the main body 201A of the image forming apparatus for feeding the set sheet S to the image forming section 201B. The sheet feeding unit 230 comprises a feeding cassette 1 for storing sheets and a sheet feeding section 5 for feeding the sheets S stored in the feeding cassette 1. The sheet feeding section 5 comprises a pickup roller 2 and a feed roller 3 and a retard roller as separation means for separating the sheets S that have been fed in multiples from the pickup roller 2.

[0021] Furthermore, a manual feed unit 235 for feeding the set sheet S to the image forming unit 201B is provided on the right side of the main body 201A of the image forming apparatus in Figure 1. The manual feed unit 235 is equipped with a manual feed tray 6 for supporting the sheet S and, like the sheet feeding unit 230, is equipped with sheet feeding means and separation means. In addition, a feeding deck 500 for feeding the set sheet S to the image forming unit 201B is provided on the right side of the main body 201A of the image forming apparatus in Figure 1, below the manual feed unit 235. Details of this feeding deck 500 will be described later.

[0022] Next, the image forming operation of the image forming apparatus 201 will be described. First, when the image information of the original is read by the image reading device 202, this image information is processed and then converted into an electrical signal and transmitted to the laser scanner 210 of the image forming unit 201B. In the image forming unit 201B, the surface of the photoreceptor drum 212, whose surface is uniformly charged to a predetermined polarity and potential by the charger 213, is sequentially exposed by laser light. As a result, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photoreceptor drum of each process cartridge 211, respectively.

[0023] Next, this electrostatic latent image is developed and visualized using each color toner, and the primary transfer bias applied to the primary transfer roller 219 sequentially superimposes and transfers the toner images of each color on each photoreceptor drum onto the intermediate transfer belt 216. As a result, a toner image is formed on the intermediate transfer belt 216.

[0024] Meanwhile, the sheet S fed by the feed roller 3 of the sheet feeding unit 230 is transported to a registration roller pair (hereinafter referred to as the registration roller pair) 240, which consists of a drive roller and a driven roller. At this time, the registration roller pair 240 is stopped from driving, and the leading edge of the sheet S comes into contact with the registration roller pair 240. This causes the leading edge of the sheet S to conform to the registration roller pair 240. Subsequently, as the sheet S is transported by the feed roller 3, a flex (loop) is formed in the sheet S, and when a predetermined loop amount is reached, the registration roller pair 240 is driven. As a result, the skew of the sheet S is corrected by the registration roller pair 240, and the skew-corrected sheet S is transported by the registration roller pair 240 to the secondary transfer section 201D. Subsequently, in the secondary transfer section 201D, the toner image is transferred onto the sheet S all at once by the secondary transfer bias applied to the secondary transfer roller 217. The sheet S onto which the toner image has been transferred is then transported to the fuser unit 201E, where it is subjected to heat and pressure, causing the toners of each color to melt and mix, and then fixed to the sheet S as a color image.

[0025] After this, the sheet S on which the image has been fixed is discharged into the discharge space V by the first discharge roller pair 225a and the second discharge roller pair 225b located downstream of the fixing unit 201E, and is loaded onto the loading section 223 formed on the bottom surface of the discharge space V. When forming images on both sides of the sheet S, after the image has been fixed, the sheet S is transported to the re-transport passage R by the reversing roller pair 222, and then transported again to the image forming unit 201B.

[0026] [Supply deck configuration] Next, the details of the feeding deck 500 as a sheet feeding device will be described using Figures 1 and 3. Figure 3 is a schematic diagram showing the configuration of the feeding deck according to the first embodiment.

[0027] As shown in Figure 1, the feeding deck 500 is a large-capacity sheet feeding device that can continuously feed a larger number of sheets S on the lifter plate 514 than the sheet S loading capacity of the feeding cassette 1 of the image forming apparatus 201. As shown in Figures 1 and 3, the feeding deck 500 includes a deck section 510 as a sheet storage section and a sheet feeding section 506 that feeds sheets and separates sheets that have been fed multiple times. The sheet feeding section 506 also includes a pickup roller 501 as a feeding roller that contacts the uppermost sheet of the sheet bundle supported by the lifter plate 514 (described later) and feeds the uppermost sheet. Furthermore, the sheet feeding section 506 includes a feed roller 502 and a retard roller 503 as a separation section that separates the sheets S fed from the pickup roller 501. Furthermore, in the feed deck 500, a pull-out roller 504 is positioned downstream of the feed roller 502 in the sheet feeding direction, which pulls the sheet S from the feed roller 502 and feeds it to the image forming apparatus 201. In addition, a feed sensor 505, which acts as a sheet detection unit, is positioned between the feed roller 502 and the pull-out roller 504 in the sheet feeding direction, that is, downstream of the sheet feeding unit 506 in the feeding direction. This feed sensor 505 detects the passage of the sheet S by outputting a signal depending on the presence or absence of the sheet S.

[0028] Furthermore, as shown in Figure 3, the deck section 510 is equipped with a lifter plate 514, which serves as a sheet support section for loading and supporting sheet bundles consisting of multiple sheets S. The height of this lifter plate 514 is controlled according to the amount of sheets S loaded by a lifting mechanism (not shown). Also, as shown in Figure 3, the deck section 510 is equipped with side end restricting plates 511, 512 and a rear end restricting plate 513. The side end restricting plates 511, 512 restrict the position of the ends of the sheets S in the width direction (side ends of the sheets) set on the lifter plate 514. The rear end restricting plate 513 restricts the position of the upstream end (rear end of the sheet) in the feeding direction of the sheets S.

[0029] These side edge restricting plates 511 and 512 are each provided with air blowing sections 511A and 512A, which serve as air handling sections. The air blowing section 511A of the side edge restricting plate 511 has a fan 511b driven by a fan motor 511M (see Figure 2) and a blowing nozzle 511a that guides the air blown from the fan 511b and blows it from the side of the sheet bundle. Similarly, the air blowing section 512A of the side edge restricting plate 512 has a fan 512b driven by a fan motor 512M (see Figure 2) and a blowing nozzle 512a that guides the air blown from the fan 512b and blows it from the side of the sheet bundle. Furthermore, the side edge restricting plates 511 and 512 are provided with floating suppression plates 511c and 512c near the spray nozzles 511a and 512a to prevent the sheet S, to which air has been sprayed, from floating up and going over the side edge restricting plates 511 and 512.

[0030] [Configuration of the control system for the image forming system] Next, the configuration of the control system in the image forming system 600 will be explained using Figure 2. Figure 2 is a block diagram showing the control system of the image forming system according to the first embodiment.

[0031] The control unit 100 according to this embodiment is provided, for example, in an image forming apparatus 201 and is configured to include a CPU 101, ROM 102, and RAM 103. The control unit 100 is a control means that comprehensively controls the image forming apparatus 201 and the feed / delivery deck 500. The control unit 100 is connected to a host device 900 and an operation unit 730, and while exchanging information with them, it performs signal processing, sequence control, etc. for various process equipment. The host device 900 is an external device such as a personal computer, image scanner, or facsimile machine.

[0032] Furthermore, the control unit 100 is connected to the fan motors 511M and 512M, the feed motor 520 which drives the pickup roller 501, the torque measuring unit 520a which measures the motor torque of the feed motor 520, the feed sensor 505, etc. The torque measuring unit 520a measures the motor torque of the feed motor 520, but it may also be a current sensor which detects the current value flowing through the feed motor 520, or a torque sensor which detects the torque generated in the pickup roller 501. In other words, the specific configuration of the torque measuring unit 520a can be anything that can measure the motor torque of the feed motor 520.

[0033] [Operation and problems when using air blowing] Next, the state of the sheet S when air is blown from the side of the sheet bundle by the air blowing sections 511A and 512A, and the problems that arise when the sheet S is fed while air is being blown, will be explained using Figures 4 and 14. Figure 4 is a schematic diagram showing the state when the air blowing operation (hereinafter referred to as "air blowing operation") is performed on the feeding deck according to the first embodiment. Figure 14 is an explanatory diagram illustrating the generation of rotational force due to the positional relationship between the pickup roller and the feed roller.

[0034] As shown in Figure 4, air is blown from the fans 511b and 512b of the air blowing sections 511A and 512A toward the sides of the sheet bundle as indicated by arrows A1 and A2. As a result, several to tens of sheets S at the top of the sheet bundle are separated and float up, while the floating of the sheets S is suppressed by the floating suppression plates 511c and 512c. This reduces the adhesion force between the sheets S, making it possible to feed even sheets S with a smooth surface, such as coated paper, with the pickup roller 501.

[0035] Incidentally, due to the design in relation to other components, for example as shown in Figure 14, the positions of the center C1 of the pickup roller 501 and the center C2 of the feed roller 502 may be offset by a distance X in the width direction perpendicular to the sheet feeding direction. In this case, when the uppermost sheet S1 is being transported by the feed roller 502, if a transport load is generated near the pickup roller 501 due to a difference in transport speed, a counterclockwise pivoting force is generated on the sheet S1. As a result, the sheet S1 is fed while rotating, causing the sheet S1 to tilt. Normally, even if a pivoting force is generated on the sheet S1, the side edges of the sheet S1 come into contact with the side edge regulating plates 511 and 512, and the stiffness of the sheet S1 suppresses the tilting. However, because the sheet S1 is lifted by the air blowing from the air blowing sections 511A and 512A, the sheet S1 is prone to bending, as shown in Figure 14. Therefore, the effect of suppressing the skewness of the sheet S1 by the side edge restricting plates 511 and 512 becomes smaller, and there is a problem that the amount of skewness of the sheet S1 may increase. Therefore, in this first embodiment, sheet feeding control is performed as follows.

[0036] [Sheet feeding control according to the first embodiment] Next, the sheet feeding control according to the first embodiment will be explained using Figures 5 and 6. Figure 5 is a flowchart showing the sheet feeding control according to the first embodiment. Figure 6 is a graph showing the relationship between the number of sheets fed and the amount of skew when sheets are fed using the sheet feeding control according to the first embodiment and when sheets are fed while air blowing is being performed.

[0037] The control unit 100 starts sheet feeding control (mode) to feed, for example, 15 sheets, which is the number of sheets required for printing in the image forming apparatus 201 (S1). First, it drives the fan motors 511M, 512M (see Figure 2) of the air blowing units 511A, 512A to start an air blowing operation that blows air onto the sides of the sheet stack (S2). As a result, several to tens of sheets S at the top of the sheet stack are separated and floated up, and the floating of the sheets S is suppressed by the floating suppression plates 511c, 512c (see Figure 4), and the adhesion force between the sheets is reduced.

[0038] Since the fan motors 511M and 512M start rotating from a stopped state, a predetermined time, such as 10 seconds, is set in advance to allow time to reach the desired rotational speed and for the levitation of the sheet S to stabilize. Then, the air blowing operation is performed until the predetermined time has elapsed (No in S3), and once the predetermined time has elapsed (Yes in S3), the air blowing operation is stopped (S4), that is, the drive of the fan motors 511M and 512M is turned OFF. As a result, the sheet S, which was in a levitated state, tries to return to the sheet bundle state before levitation as the air between the sheets is released, but the adhesion force between the sheets remains reduced until it returns to the sheet bundle state, so the sheet feeding operation is started (S5).

[0039] The start of this feeding operation refers to the feeding of the sheet S by rotating the pickup roller 501, driven by the feeding motor 520, while the pickup roller 501 is in contact with the top sheet S in the sheet bundle. Subsequently, if the sheets S are fed twice, separation is performed in the separation section consisting of the feed roller 502 and the retard roller 503, and the passage is detected by the feeding sensor 505. In this first embodiment, the feeding operation is repeated until the required number of sheets S, for example 15 sheets, has been fed (No in S6), and once the required number of sheets has been fed (Yes in S6), the sheet feeding control is terminated (S7).

[0040] Here, we will explain the relationship between the number of sheets fed and the amount of skew when 15 sheets are fed using the sheet feeding control according to the first embodiment, and when sheets are fed while air blowing is being performed. Figure 6 shows the change in the amount of skew in the longitudinal direction (amount of inclination relative to the conveying direction) for each of the 15 sheets fed from the feeding deck 500. The sheets are coated paper (OK Topcoat+ 104.7g / m²). 2 This is the A3Y configuration, and during the air blowing operation, air is blown from both sides of the sheet bundle (see Figure 4). In addition, the fan motors 511M and 512M are controlled by PWM control, and φ97mm blower fans are used for fans 511b and 512b. During the air blowing operation, air was blown with a PWM duty cycle of 40%.

[0041] When the sheet feeding operation is performed while the air blowing operation is in progress, that is, when the sheet feeding operation is performed while the air blowing operation is continued, the variation in the amount of skew for each sheet feeding (standard deviation σ = 0.32) is large. In addition, the amount of inclination (average value = -0.89) is also large. On the other hand, as in the sheet feeding control in this first embodiment, when the sheet feeding operation is performed after the air blowing operation is stopped, the amount of skew is stable (standard deviation σ = 0.12), and the amount of skew (average value = 0.30) is also small.

[0042] As described above, with the sheet feeding control according to this first embodiment, even sheets with a smooth surface, such as coated paper, can have their adhesion reduced by separating the top few to tens of sheets in the sheet bundle with the air blowing operation. This prevents, for example, the pickup roller 501 from slipping and making it impossible to transport the sheets, and enables feeding even sheets with high adhesion to each other. Furthermore, since the sheet feeding operation is performed after the air blowing operation is stopped, the amount of skew of the sheets fed from the feeding deck 500 can be improved compared to when the feeding operation is performed while the air blowing operation is still running. Consequently, when correcting the skew of the sheets in the register roller pair 240, the required amount of skew correction is reduced, which reduces the variation in the position of the sheets transported to the secondary transfer unit 201D and improves printing accuracy (quality).

[0043] <Second Embodiment> Next, a second embodiment, which is a modified version of the first embodiment described above, will be explained with reference to Figure 7. Figure 7 is a flowchart showing the sheet feeding control according to the second embodiment. In this explanation of the second embodiment, the same reference numerals as in the first embodiment will be used, and their explanations will be omitted.

[0044] In this second embodiment, we will describe the case where, for example, 50 sheets are fed as the number of sheets required for printing in the image forming apparatus 201. As described above, when the air blowing operation is performed, as shown in Figure 4, several to several dozen sheets at the top of the sheet bundle are separated and float up, and the adhesion force between those sheets is reduced. However, although the number of sheets that float up varies depending on the position of the blowing nozzles 511a, 512a and the position of the float-suppressing plates 511c, 512c, the number of sheets that float up in a single air blowing operation is limited to several to several dozen. In this second embodiment, we will describe the case where the number of sheets separated in a single air blowing operation is 10. Therefore, when feeding 50 sheets, it is not possible to reduce the adhesion force between all 50 sheets in a single air blowing operation. Thus, the sheet feeding control according to the second embodiment will be described below.

[0045] [Sheet feeding control according to the second embodiment] The control unit 100 starts sheet feeding control to feed, for example, 50 sheets, which is the number of sheets required for printing in the image forming apparatus 201 (S11). First, it drives the fan motors 511M and 512M of the air blowing units 511A and 512A (see Figure 2) to start the air blowing operation, which blows air onto the sides of the sheet bundle (S12). As a result, 10 sheets S at the top of the sheet bundle are separated and float up, and the floating of the sheets S is suppressed by the floating suppression plates 511c and 512c (see Figure 4), and the adhesion force between the sheets is reduced.

[0046] Next, the air blowing operation is performed until a predetermined time has elapsed (No in S13), and once the predetermined time has elapsed (Yes in S13), the air blowing operation is stopped (S14). As a result, the sheets S, which were in a floating state, attempt to return to their pre-floating sheet bundle state as the air between the sheets is released. However, until they return to the sheet bundle state, the adhesion force between the sheets remains reduced, so the sheet feeding operation is started (S15).

[0047] Specifically, the top sheet S of the sheet bundle is fed by the pickup roller 501, and if the sheets S are fed multiple times, they are separated in the separation section consisting of the feed roller 502 and the retard roller 503. Next, in this second embodiment, it is determined whether or not the feeding of the required number of sheets S, for example 50 sheets, has been completed (S16). If the feeding of the required number of sheets has not been completed (No in S16), it is determined whether or not 10 sheets, a predetermined number, have been fed since the start of the feeding operation (S17). Specifically, the feeding operation is repeated until the feeding of the predetermined number (10 sheets) has been completed (No in S17), and once the feeding of the predetermined number (10 sheets) is complete (Yes in S17), the process returns to step S12 and the air blowing operation is resumed. In other words, the conditions are that the feeding of the predetermined number of sheets has been completed and that the feeding of the required number of sheets has not been completed. Therefore, if this condition is met during the execution of sheet feeding control, the feeding operation is stopped and the air blowing operation is restarted. After that, as described above, once a predetermined time has elapsed (Yes in S13), the air blowing operation is stopped (S14) and the sheet feeding operation S is started again (S15).

[0048] Then, by repeating the above air blowing operation, stopping, and feeding operation of a predetermined number of sheets, once the required number of sheets (50 sheets) has been fed (Yes in S16), the sheet feeding control is terminated (S18).

[0049] As explained above, according to the sheet feeding control of this second embodiment, the number of sheets required for printing by the image forming apparatus 201 is greater than the number of sheets that can be handled in a single air blowing operation. However, as with the first embodiment, since no air blowing operation is performed during the feeding operation, it is possible to feed sheets with reduced skew.

[0050] In this second embodiment, the predetermined number of sheets to be continuously fed was described as 10, corresponding to the number of sheets that are processed by a single air-blowing operation. However, the number of sheets that are processed by a single air-blowing operation will differ depending on the thickness of the sheets, for example, so the predetermined number is not limited to this value.

[0051] <Third Embodiment> Next, a third embodiment, which is a modified version of the first and second embodiments described above, will be explained using Figures 8 and 9. Figure 8 is a flowchart showing the sheet feeding control according to the third embodiment. Figure 9 is a graph showing the relationship between the number of sheets fed and the feeding time in the section up to the sheet detection sensor according to the third embodiment. In this explanation of the third embodiment, the same reference numerals are used for parts similar to those in the first and second embodiments, and their explanations are omitted.

[0052] In this third embodiment, we will describe a case where, for example, 50 sheets are fed as the number of sheets required for printing in the image forming apparatus 201. As described above, the number of sheets that float up in the air blowing operation varies depending on the position of the blowing nozzles 511a, 512a and the position of the float suppression plates 511c, 512c, but the number of sheets that float up in a single air blowing operation is limited to several to several dozen. Therefore, similar to the second embodiment, when feeding 50 sheets, it is not possible to reduce the adhesion between sheets for all 50 sheets in a single air blowing operation.

[0053] Furthermore, the sheets that were lifted by the air blowing operation will fall by their own weight over time after the air blowing operation stops, and the sheets that were dispersed by the air will return as a sheet bundle, meaning that the adhesion force between the sheets will increase. If the adhesion force between the sheets is too high, the conveying force of the sheets S by the pickup roller 501 will be insufficient, which may result in a failure to feed the sheets S. In this third embodiment, this failure to feed is determined by the time it takes for the feed sensor 505 (see Figures 1 to 3) to detect the passage of the sheets S. That is, if the sheets S are not detected from the start of driving the pickup roller 501 until the delay limit time (480 ms), it is determined that there is a failure to feed. Note that this delay limit time is the same as the time at which the control unit 100 times out and determines an error if the sheets are not being fed.

[0054] Figure 9 is a graph plotting the section transport time for each sheet transport, from the start of driving the feed motor 520 (see Figure 2) that drives the pickup roller 501 on the feed deck 500 until the leading edge of the sheet S is detected by the feed sensor 505. As described above, the delay limit time TB, shown by the dashed line, is 480 ms, and this is the delay limit line at which the transport sequence will not be established if detection by the feed sensor 505 is delayed beyond the delay limit time TB. In this third embodiment, a threshold TA (420 ms), shown by the dotted line, is set as a threshold (set time) to determine if there is a delay tendency before reaching the delay limit time TB (480 ms) (a time shorter than the delay limit time TB).

[0055] In this embodiment, the threshold TA uses time as a parameter, but essentially it is a threshold for transport resistance (adhesion force between sheets), and can be described as a threshold for determining whether the load generated when the sheets S are fed by the pickup roller 501 is greater than or equal to a set load. In other words, the conditions may be set such that the load generated when feeding the sheets lasts longer than the set load and the required number of sheets have not been fed. If these conditions are met, the feeding operation may be stopped and the air blowing operation may be restarted.

[0056] [Sheet feeding control according to the third embodiment] The control unit 100 starts sheet feeding control to feed, for example, 50 sheets, which is the number of sheets required for printing in the image forming apparatus 201 (S21). First, it drives the fan motors 511M and 512M (see Figure 2) of the air blowing units 511A and 512A to start an air blowing operation that blows air onto the sides of the sheet stack (S22). As a result, several to several dozen sheets S at the top of the sheet stack are separated and float up, while the floating of the sheets S is suppressed by the floating suppression plates 511c and 512c (see Figure 4), and the adhesion force between the sheets is reduced.

[0057] Next, the air blowing operation is performed until a predetermined time has elapsed (No in S23), and once the predetermined time has elapsed (Yes in S23), the air blowing operation is stopped (S24). As a result, the sheets S, which were in a floating state, attempt to return to their pre-floating sheet bundle state as the air between the sheets is released. However, since the adhesion force between the sheets remains reduced until they return to the sheet bundle state, the sheet feeding operation is started (S25).

[0058] Specifically, the top sheet S of the sheet bundle is fed by the pickup roller 501, and if the sheets S are fed multiple times, they are separated in the separation section consisting of the feed roller 502 and the retard roller 503. Next, in this third embodiment, it is determined whether or not the feeding of the required number of sheets S, for example 50 sheets, has been completed (S26). If the feeding of the required number of sheets has not been completed (No in S26), it is determined whether or not the section transport time, based on the detection by the feeding sensor 505 as described above, is less than or equal to the threshold TA (S27). Specifically, if the section transport time is less than or equal to the threshold TA (Yes in S27), the feeding operation is repeated, and if the section transport time becomes greater than the threshold TA (No in S27), the process returns to step S22 and the air blowing operation is resumed. In other words, the conditions are that the section transport time is longer than the threshold TA and that the feeding of the required number of sheets has not been completed. Therefore, if these conditions are met during the execution of sheet feeding control, the feeding operation is stopped and the air blowing operation is resumed. After a predetermined time has elapsed (Yes in S23), the air blowing operation is stopped (S24), and the sheet S feeding operation is restarted (S25).

[0059] Then, the sheet feeding operation is repeated as long as the start and stop of the air blowing operation and the section transport time are below the threshold TA. Once the required number of sheets (50 sheets) have been fed (Yes in S26), the sheet feeding control is terminated (S28).

[0060] As explained above, according to the sheet feeding control of this third embodiment, the number of sheets required for printing by the image forming apparatus 201 is greater than the number of sheets that can be handled in a single air blowing operation. However, as with the first embodiment, since no air blowing operation is performed during the feeding operation, it is possible to feed sheets with reduced skew. Furthermore, by determining the delay caused by the increased transport resistance due to the adhesion force between sheets from the delay trend of the feeding time, the air blowing operation can be performed again each time, so that the transport sequence does not fail.

[0061] <Fourth Embodiment> Next, a fourth embodiment, which is a modified version of the first to third embodiments described above, will be explained using Figures 10 and 11. Figure 10 is a flowchart showing the sheet feeding control according to the fourth embodiment. Figure 11 is a graph showing the relationship between the number of sheets fed and the motor torque of the feeding motor according to the fourth embodiment. In this explanation of the fourth embodiment, the same reference numerals as in the first to third embodiments will be used for the same parts, and their explanations will be omitted.

[0062] In this fourth embodiment, we will describe a case where, for example, 50 sheets are fed as the number of sheets required for printing in the image forming apparatus 201. As described above, the number of sheets that can be lifted by a single air blowing operation is limited to several to several dozen sheets. Therefore, as in the second and third embodiments, when feeding 50 sheets, it is not possible to reduce the adhesion between sheets for all 50 sheets with a single air blowing operation.

[0063] Furthermore, the sheets that were lifted by the air blowing operation will fall by their own weight over time after the air blowing operation stops, and the sheets that were dispersed by the air will return as a sheet bundle, meaning that the adhesion force between the sheets will increase. If the adhesion force between the sheets is large, the conveying force of the sheets S by the pickup roller 501 will be insufficient, and there is a risk of a failure in feeding the sheets S. In this fourth embodiment, this failure in feeding is determined by the magnitude of the motor torque of the feeding motor 520 measured by the torque measuring unit 520a (see Figure 2). That is, if the motor torque of the feeding motor 520 when the sheets S are fed by the pickup roller 501 reaches the limit judgment torque (0.17 N·m), it is determined to be a failure in feeding. Note that this limit judgment torque is synonymous with the torque at which the control unit 100 determines an error, which is the motor torque generated by a load that prevents the pickup roller 501 from stably feeding the sheets.

[0064] Figure 11 is a graph plotting the motor torque measured by the torque measuring unit 520a for each sheet feeding operation when the sheet S is conveyed by the pickup roller 501 on the feeding deck 500. As described above, the limit judgment torque MTB, shown by the dashed line, is 0.17 N·m, and this is the limit torque at which a feeding failure is determined to occur if the motor torque measured by the torque measuring unit 520a is greater than the limit judgment torque MTB. In this fourth embodiment, a threshold value MTA (0.16 N·m), shown by the dotted line, is set as a threshold value (set torque) to determine that the conveying resistance is tending to increase before reaching the limit judgment torque MTB (0.17 N·m). This threshold value MTA (0.16 N·m) should be a torque smaller than the limit judgment torque MTB.

[0065] In this embodiment, the threshold MTA uses torque as a parameter, but essentially it is a threshold for conveying resistance (adhesion force between sheets), and can be described as a threshold for determining whether the load generated when the sheets S are fed by the pickup roller 501 is greater than or equal to a set load. In other words, the conditions may be set such that the load generated when feeding the sheets lasts longer than the set load and the required number of sheets have not been fed. If these conditions are met, the feeding operation may be stopped and the air blowing operation may be restarted.

[0066] [Sheet feeding control according to the fourth embodiment] The control unit 100 starts sheet feeding control to feed, for example, 50 sheets, which is the number of sheets required for printing in the image forming apparatus 201 (S31). First, it drives the fan motors 511M and 512M (see Figure 2) of the air blowing units 511A and 512A to start an air blowing operation that blows air onto the sides of the sheet bundle (S32). As a result, several to several dozen sheets S at the top of the sheet bundle are separated and floated up, and the floating up of the sheets S is suppressed by the floating suppression plates 511c and 512c (see Figure 4), and the adhesion force between the sheets is reduced.

[0067] Next, the air blowing operation is performed until a predetermined time has elapsed (No in S33), and once the predetermined time has elapsed (Yes in S33), the air blowing operation is stopped (S34). As a result, the sheets S, which were in a floating state, attempt to return to their pre-floating sheet bundle state as the air between the sheets is released. However, since the adhesion force between the sheets remains reduced until they return to the sheet bundle state, the sheet feeding operation is started (S35).

[0068] Specifically, the top sheet S of the sheet bundle is fed by the pickup roller 501, and if the sheets S are fed multiple times, they are separated in the separation section consisting of the feed roller 502 and the retard roller 503. Next, in this fourth embodiment, it is determined whether or not the feeding of the required number of sheets S, for example 50 sheets, has been completed (S36). If the feeding of the required number of sheets has not been completed (No in S36), it is determined whether or not the motor torque of the feeding motor 520, based on the measurement by the torque measuring unit 520a as described above, is below the threshold MTA (S37). Specifically, if the motor torque is below the threshold MTA (Yes in S37), the feeding operation is repeated, and when the motor torque becomes greater than the threshold MTA (No in S37), the process returns to step S32 and the air blowing operation is resumed. In other words, the conditions are set as follows: the motor torque becomes greater than the threshold MTA and the feeding of the required number of sheets has not been completed. Therefore, if this condition is met during the execution of sheet feeding control, the feeding operation is stopped and the air blowing operation is restarted. After a predetermined time has elapsed (Yes in S33), the air blowing operation is stopped (S34) and the sheet feeding operation S is started again (S35).

[0069] Then, the above air blowing operation is started and stopped, and the sheet feeding operation is repeated when the motor torque is below the threshold MTA. Once the required number of sheets (50 sheets) have been fed (Yes in S36), the sheet feeding control is terminated (S38).

[0070] As explained above, according to the sheet feeding control of this fourth embodiment, the number of sheets required for printing by the image forming apparatus 201 is greater than the number of sheets that can be handled in a single air blowing operation. However, as with the first embodiment, since no air blowing operation is performed during the feeding operation, it is possible to feed sheets with reduced skew. Furthermore, by determining the increase in transport resistance due to the adhesion force between sheets from the increasing trend of the motor torque of the feeding motor 520, the air blowing operation can be performed again each time, so that a feeding failure can occur before it happens.

[0071] <Fifth Embodiment> Next, a fifth embodiment, which is a modified version of the first embodiment described above, will be explained using Figures 12 and 13. Figure 12 is a flowchart showing the sheet feeding control according to the fifth embodiment. Figure 13 is a diagram showing the mode selection screen according to the fifth embodiment. In this description of the fifth embodiment, the same reference numerals as in the first embodiment will be used for the same parts, and their explanations will be omitted.

[0072] In the first embodiment described above, the control unit 100 controls the air blowing operation, and after stopping the air blowing operation, a mode is described in which the feeding operation is performed while the air blowing operation is stopped. By performing the feeding operation while the air blowing operation is stopped in this way, the amount of sheet skew can be reduced and the printing accuracy (image formation quality) can be improved, but productivity decreases because the air blowing operation and the feeding operation are performed alternately. Therefore, in this fifth embodiment, the above mode can be executed as a printing accuracy priority mode (first mode). Furthermore, a productivity priority mode (second mode) can also be executed, in which the feeding operation is performed while the air blowing operation is performed even if there is a risk that the amount of skew will increase and the printing accuracy will decrease. In other words, the printing accuracy priority mode and the productivity priority mode can be selectively executed.

[0073] [Sheet feeding control according to the fifth embodiment] The control unit 100 starts sheet feeding control (mode) to feed, for example, 15 sheets, which is the number of sheets required for printing in the image forming apparatus 201 (S41). First, as shown in Figure 13, a screen for selecting the printing mode is displayed on the operation unit 730, and the user is asked to select either the productivity priority mode or the printing accuracy priority mode (S42). If the user selects the printing accuracy priority mode (Yes in S42), the printing accuracy priority mode control, which is the same as in the first embodiment, is executed.

[0074] In print accuracy priority mode, first, the fan motors 511M and 512M (see Figure 2) of the air blowing units 511A and 512A are driven to start the air blowing operation, which blows air onto the sides of the sheet bundle (S43). As a result, the 10 sheets S above the sheet bundle are separated and float up, while the floating of the sheets S is suppressed by the floating suppression plates 511c and 512c (see Figure 4), and the adhesion force between the sheets is reduced.

[0075] Next, the air blowing operation is performed until a predetermined time has elapsed (No in S44), and once the predetermined time has elapsed (Yes in S44), the air blowing operation is stopped (S45). As a result, the sheets S, which were in a floating state, attempt to return to their pre-floating sheet bundle state as the air between the sheets is released. However, since the adhesion force between the sheets remains reduced until they return to the sheet bundle state, the sheet feeding operation is started (S46).

[0076] Specifically, the top sheet S of the sheet bundle is fed by the pickup roller 501, and if the sheets S are fed multiple times, they are separated in the separation section consisting of the feed roller 502 and the retard roller 503. Subsequently, the feeding operation is repeated until the required number of sheets S, for example 15 sheets, has been fed (No in S47), and once the required number of sheets has been fed (Yes in S47), the sheet feeding control is terminated (S53).

[0077] On the other hand, if a mode other than the print accuracy priority mode, i.e., the productivity priority mode, is selected in step S42 (No. in S42), the productivity priority mode is executed.

[0078] In productivity priority mode, first, the fan motors 511M and 512M (see Figure 2) of the air blowing sections 511A and 512A are driven to start the air blowing operation, which blows air onto the sides of the sheet bundle (S48). As a result, the 10 sheets S above the sheet bundle are separated and float up, while the floating of the sheets S is suppressed by the floating suppression plates 511c and 512c (see Figure 4), and the adhesion force between the sheets is reduced.

[0079] Next, the system waits while performing the air blowing operation until a predetermined time has elapsed (No. in S49). Once the predetermined time has elapsed (Yes in S49), the floating of the sheet S stabilizes, and the sheet S feeding operation is started while the air blowing operation is performed (S50). That is, the top sheet S of the sheet bundle is fed by the pickup roller 501, and if the sheets S are fed multiple times, they are separated in the separation section consisting of the feed roller 502 and the retard roller 503. Subsequently, the feeding operation is repeated until the required number of sheets, for example 15 sheets S, has been fed (No. in S51). Once the required number of sheets has been fed (Yes in S51), the air blowing operation is stopped (S52), and the sheet feeding control is terminated (S53).

[0080] As explained above, in this fifth embodiment, the user can switch between prioritizing productivity (printing time) and print accuracy. By controlling the air blowing operation and the feed operation according to the mode selected by the user, it becomes possible to accommodate a variety of use cases.

[0081] In this fifth embodiment, the same control as the sheet feeding control in the first embodiment was described as the print accuracy priority mode. However, the invention is not limited to this, and the same control as the sheet feeding control in the second to fourth embodiments may also be used.

[0082] [Possibility of other embodiments] In the first to fifth embodiments described above, sheet feeding control in a feeding deck 500 equipped with air blowing units 511A and 512A was described. However, the sheet feeding control according to this embodiment may also be performed in a sheet feeding unit 230 having a feeding cassette 1 or a manual feeding unit 235 having a manual feeding tray 6 equipped with an air blowing unit. Furthermore, when performing sheet feeding control according to this embodiment in the sheet feeding unit 230, it may be performed at any stage in the vertical direction. In other words, the sheet support unit that supports the sheet bundle may have any configuration.

[0083] Furthermore, in the first to fifth embodiments described above, a system for feeding and separating sheets was described that includes a pickup roller for feeding sheets and a feed roller and retard roller for separating the double-feeded sheets. However, the system is not limited to this, and the configuration of the sheet feeding unit for feeding sheets can be anything, such as a system that feeds sheets by vacuum suction onto a belt or the like.

[0084] Furthermore, in the third and fourth embodiments described above, a system was described in which the increase in adhesion force between sheets was determined based on the sheet feeding time and motor torque, and the air blowing operation was performed again. However, the system is not limited to this, and it is also acceptable to directly detect the sheet transport load, or to calculate it based on the feeding time and motor torque, and determine the increase in adhesion force between sheets from the sheet transport resistance.

[0085] Furthermore, in the first to fifth embodiments described above, the control unit 100 was described in which it is provided in the image forming apparatus 201. However, it is not limited to this, and it may also be provided in the feed deck 500, that is, as long as the control unit capable of controlling the sheet feed unit and the air blowing unit is electrically connected to them, it may be located in any of the devices.

[0086] This disclosure can also be implemented by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more functions. [Explanation of Symbols]

[0087] 100...Control Unit / 201B...Image Forming Unit / 500...Feeding Deck (Sheet Feeding Device) / 501...Pickup Roller (Feeding Roller) / 505...Feeding Sensor (Sheet Detection Unit) / 506...Sheet Feeding Unit / 511A, 512A...Air Blowing Unit (Air Discharge Unit) / 511a, 512a...Nozzle / 511b, 512b...Fan / 514...Lifter Plate (Sheet Support Unit) / 520...Feeding Motor (Motor) / 600...Image Forming System / S...Sheet

Claims

1. A sheet support section that supports the sheet bundle, A sheet feeding unit that contacts the uppermost sheet of the sheet bundle supported by the sheet support unit and performs a feeding operation to feed the uppermost sheet, An air blowing unit that performs a blowing operation to blow air onto the side surface of a sheet bundle supported by the sheet support unit, The system includes a control unit that controls the feeding operation of the sheet feeding unit and the blowing operation of the air blowing unit, The control unit can execute a feeding mode in which, when the number of sheets to be fed exceeds a predetermined number, the air blowing unit performs the blowing operation, stops the blowing operation, and then, with the blowing operation stopped, the sheet feeding unit performs the feeding operation to feed the predetermined number of sheets, and then stops the feeding operation by the sheet feeding unit, performs the blowing operation with the air blowing unit, stops the blowing operation, and then, with the blowing operation stopped, resumes the feeding operation to feed sheets by the sheet feeding unit. A sheet feeding device characterized by the following features.

2. A sheet support section that supports the sheet bundle, A sheet feeding unit that contacts the uppermost sheet of the sheet bundle supported by the sheet support unit and performs a feeding operation to feed the uppermost sheet, An air blowing unit that performs a blowing operation to blow air onto the side surface of a sheet bundle supported by the sheet support unit, The system includes a control unit that controls the feeding operation of the sheet feeding unit and the blowing operation of the air blowing unit, In a feeding mode in which the control unit performs the spraying operation using the air blowing unit, and after stopping the spraying operation, performs the feeding operation using the sheet feeding unit to feed a predetermined number of sheets while the spraying operation is stopped, If the number of sheets to be fed exceeds the predetermined number, after feeding the predetermined number of sheets, the feeding operation by the sheet feeding unit is stopped, the air blowing operation is performed by the air blowing unit, and after the air blowing operation is stopped, the feeding restart operation is performed, in which the sheet feeding unit feeds sheets while the air blowing operation is stopped. A sheet feeding device characterized by the following features.

3. A sheet support section that supports the sheet bundle, A sheet feeding unit that contacts the uppermost sheet of the sheet bundle supported by the sheet support unit and performs a feeding operation to feed the uppermost sheet, An air blowing unit that performs a blowing operation to blow air onto the side surface of a sheet bundle supported by the sheet support unit, A sheet detection unit that detects a sheet downstream of the sheet feeding unit in the feeding direction, The system includes a control unit that controls the feeding operation of the sheet feeding unit and the blowing operation of the air blowing unit, The control unit is capable of executing a feeding mode in which it performs the spraying operation using the air blowing unit, and after stopping the spraying operation, it performs the feeding operation using the sheet feeding unit to feed the sheet while the spraying operation is stopped. In the feeding mode, if the feeding time from when the sheet is fed by the sheet feeding unit until the sheet is fed to the sheet detection unit is longer than the set time, and the required number of sheets have not been fed, the control unit stops the feeding operation by the sheet feeding unit, performs the blowing operation by the air blowing unit, and after stopping the blowing operation, performs a feeding restart operation in which the sheet feeding unit feeds the sheets while the blowing operation is stopped. A sheet feeding device characterized by the following features.

4. A sheet support section that supports the sheet bundle, A sheet feeding unit that contacts the uppermost sheet of the sheet bundle supported by the sheet support unit and performs a feeding operation to feed the uppermost sheet, An air blowing unit that performs a blowing operation to blow air onto the side surface of a sheet bundle supported by the sheet support unit, The system includes a control unit that controls the feeding operation of the sheet feeding unit and the blowing operation of the air blowing unit, The sheet feeding unit includes a feeding roller that contacts the uppermost sheet to feed the sheet, and a motor that drives the feeding roller. The control unit is capable of executing a feeding mode in which it performs the spraying operation using the air blowing unit, and after stopping the spraying operation, it performs the feeding operation using the sheet feeding unit to feed the sheet while the spraying operation is stopped. In the feeding mode, if the motor torque output by the sheet feeding unit when feeding sheets is greater than the set torque and the required number of sheets have not been fed, the control unit stops the feeding operation by the sheet feeding unit, performs the blowing operation by the air blowing unit, and after stopping the blowing operation, performs a feeding restart operation in which the sheet feeding unit feeds sheets while the blowing operation is stopped. A sheet feeding device characterized by the following features.

5. A sheet support section that supports the sheet bundle, A sheet feeding unit that contacts the uppermost sheet of the sheet bundle supported by the sheet support unit and performs a feeding operation to feed the uppermost sheet, An air blowing unit that performs a blowing operation to blow air onto the side surface of a sheet bundle supported by the sheet support unit, The system includes a control unit that controls the feeding operation of the sheet feeding unit and the blowing operation of the air blowing unit, The control unit is capable of executing a feeding mode in which it performs the spraying operation using the air blowing unit, and after stopping the spraying operation, it performs the feeding operation using the sheet feeding unit to feed the sheet while the spraying operation is stopped. In the feeding mode, if the load generated when the sheet feeding unit feeds the sheets is greater than the set load and the required number of sheets have not been fed, the control unit stops the feeding operation by the sheet feeding unit, performs the blowing operation by the air blowing unit, and after stopping the blowing operation, performs a feeding restart operation in which the sheet feeding unit feeds the sheets while the blowing operation is stopped. A sheet feeding device characterized by the following features.

6. In the aforementioned supply mode, the air blowing unit performs the blowing operation for a predetermined period of time, and then stops the blowing operation. A sheet feeding device according to any one of claims 1 to 5.

7. The aforementioned feeding mode is the first mode, The control unit performs the first mode and the second mode, in which the air blowing unit performs the blowing operation while the supply operation is performed. A sheet feeding device according to any one of claims 1 to 6.

8. The air blowing section includes a fan that blows air and a nozzle that guides the air blown by the fan to the side surface of the sheet bundle supported by the sheet support section. A sheet feeding device according to any one of claims 1 to 7.

9. A sheet feeding device according to any one of claims 1 to 8, The system includes an image forming unit that forms an image on a sheet fed from the aforementioned sheet feeding device. An image forming system characterized by the following features.

Images