Sheet feeding apparatus and image forming apparatus

Abstract

The invention discloses a sheet feeding apparatus and an image forming apparatus. A sheet feeding apparatus includes: a support portion for supporting a stack of sheets; a feeder for separating and feeding the sheets one by one from the sheet bundle; an air blower for blowing air to a side end of the stack of sheets; and a controller for performing a blowing operation of blowing air to a side end of the sheet through the air blower, and a feeding operation of feeding the sheet through the feeder. After the blowing operation is executed, the controller executes the feeding operation in a state in which the blowing operation is stopped in a case where a predetermined time has not elapsed from completion of the blowing operation, and the feeding operation is performed in a state in which the blowing operation is stopped in a case where the predetermined time has not elapsed. And performing another blowing operation in a case where a predetermined time has elapsed from completion of the blowing operation and performing the feeding operation in a state in which the other blowing operation is stopped.

Description

Technical Field

[0001] The present invention relates to a sheet feeding device that feeds sheets and an image forming apparatus that forms an image on a sheet. Background Art

[0002] Japanese Patent Application Publication No. H04-023747 discloses a sheet feeding device that reduces close contact between sheets by blowing air onto the side surfaces of a sheet stack with a small blower in order to facilitate feeding of sheets while separating the sheets one by one. Furthermore, Japanese Patent Application Publication No. 2023-102814 discloses that, after performing a blowing operation of blowing air onto the side surfaces of a sheet stack, a sheet feeding operation is performed with the blowing operation stopped. However, even when close contact between sheets is reduced by blowing air, the adsorption force between the sheets may increase as time passes after the blowing operation is completed. As a result, sheet separation defects may occur. Summary of the Invention

[0003] An object of the present invention is to provide a sheet feeding device and an image forming apparatus capable of suppressing the occurrence of separation defects of sheets.

[0004] 14. The sheet feeding device according to claim 13, wherein the control unit is configured to control the sheet feeding mechanism to be used for the sheet feeding apparatus and the control unit to control the sheet feeding mechanism so as to prevent the sheet from being lost due to the loss of the sheet feeding mechanism.

[0005] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram of an image forming apparatus according to an embodiment.

[0007] Figure 2 is a block diagram illustrating a control system of the image forming apparatus according to the embodiment.

[0008] Figure 3 is a perspective view illustrating a feeding device according to the embodiment.

[0009] Figure 4 is a cross-sectional view of a feeding device according to the embodiment.

[0010] Figure 5 is a flowchart illustrating a feed control method according to an embodiment.

[0011] Figure 6 is an example of transition of the adsorption force between sheets with respect to time in a state in which the sheets are retained on the sheet bundle.

[0012] Figure 7 yes Figure 6 An enlarged graph of a portion of the graph.

[0013] Figure 8 is a schematic diagram illustrating a method for measuring the adsorption force between sheets.

[0014] Figure 9 is a top view of a feeding device according to an embodiment.

[0015] Figure 10 is a flowchart illustrating a feed control method according to a comparative example. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings.

[0017] (Image Forming Apparatus)

[0018] Figure 1 1 is a schematic diagram illustrating a cross section of an image forming apparatus 201 according to an embodiment. The image forming apparatus 201 is a laser beam printer using an electrophotographic process. The image forming apparatus 201 can form (record) images on a sheet S and can communicate with the control section 100 ( Figure 2 ) is a full-color or monochrome image corresponding to image information (print image data) received by the host device 900. As the sheet S which is the recording material (recording medium), various sheet materials of different sizes and materials can be used, for example, paper such as plain paper and thick paper, sheet materials to which surface treatment is applied such as coated paper, sheet materials of special shapes such as envelopes and index paper, plastic films, and cloth.

[0019] Figure 2 The control section 100 shown in FIG. 1 is a control unit that collectively controls the operation of the image forming apparatus 201. The control section 100 exchanges information with the host device 900 and the operation section 730. Furthermore, the control section 100 performs signal processing, sequence control, and the like for various types of processing devices. Here, the host device 900 is a personal computer, an image scanner, a facsimile machine, or the like.

[0020] like Figure 1 As shown in FIG, the image forming apparatus 201 includes an image forming apparatus main assembly (hereinafter referred to as the apparatus main assembly 201A), an image forming portion 201B, and an image reading device 202. The image forming portion 201B is housed in the apparatus main assembly 201A. The image reading device 202 is mounted approximately horizontally on the upper surface of the apparatus main assembly 201A. In the vertical direction, an ejection space V is formed between the image reading device 202 and the apparatus main assembly 201A, and a sheet S on which an image has been formed is ejected into this ejection space.

[0021] In addition, the image forming apparatus 201 is provided with one or more (in the illustrated example, four) cassette feeding portions 230 provided in the apparatus main assembly 201A, a manual feeding portion 235 provided on a side surface of the apparatus main assembly 201A, and an optional feeding device 500 connected to the apparatus main assembly 201A. Next, the configuration of the optional feeding device 500 will be described.

[0022] Each cassette feeding portion 230 includes a cassette 1 (storage device) as a sheet accommodating member that accommodates sheets S, a pickup roller 2 as a feeding member that feeds the sheets S, and separation conveying portions (3 and 4) that convey the sheets S while separating the sheets S. The separation conveying portion in this embodiment includes a feed roller 3 and a retard roller 4 that forms a separation nip together with the feed roller 3. The pickup roller 2, the feed roller 3, and the retard roller 4 serve as a feeding unit that feeds the sheets S one by one from the cassette 1.

[0023] The manual feed portion 235 includes a manual feed tray 5 on which a user can manually set sheets S and a feeding unit that feeds sheets S from the manual feed tray 5. The feeding unit may have the same configuration as the feeding units (2, 3, and 4) in the cassette feeding portion 230.

[0024] The image forming portion 201B is an electrophotographic engine of a tandem type and an intermediate transfer type, and serves as an image forming means for forming an image on a sheet S. The image forming portion 201B includes four process cartridges 211 , a laser scanner 210 , an intermediate transfer unit 201C, a secondary transfer portion 201D, and a fixing portion 201E.

[0025] The four process cartridges 211 are process units that form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Each process cartridge 211 includes a photosensitive drum 212 as an image bearing member, a charging roller 213 as a charging member, and a developing unit 214 as a developing member. The developing unit 214 includes a developing roller that carries toner as a developer and supplies the toner to the photosensitive drum 212, and a developing container that holds the toner. Incidentally, a toner cartridge 215 is mounted in the upper portion of the apparatus main assembly 201A as a replenishing container for replenishing toner to each of the four developing units 214.

[0026] The laser scanner 210 as an exposure unit includes a laser light source that emits a laser beam and an exposure light optical system (polygonal mirror, etc.) that guides the laser beam toward the surface of the photosensitive drum 212 in each process cartridge 211. Incidentally, as the exposure unit, an LED exposure device in which light emitting elements (LEDs) are arranged in the direction of the rotation axis of the photosensitive drum 212 can be used.

[0027] The intermediate transfer unit 201C includes an intermediate transfer belt 216 as an intermediate transfer member and a plurality of rollers (216a, 216b, and 219). The intermediate transfer belt 216 is stretched by a drive roller 216a and a tension roller 216b, and is rotated by the drive roller 216a. In addition, four primary transfer rollers 219 are arranged on the inner circumference of the intermediate transfer belt 216 and at positions across the intermediate transfer belt 216 and facing the photosensitive drum 212.

[0028] The secondary transfer portion 201D is a transfer portion that performs transfer of a toner image to a sheet S and is a nip formed between the secondary transfer roller 217 and the intermediate transfer belt 216. The secondary transfer roller 217 is disposed on the outer peripheral side of the intermediate transfer belt 216 and at a position opposite to the drive roller 216a across the intermediate transfer belt 216.

[0029] The fixing section 201E includes a heating member 220b (fixing member), a heat source for heating the heating member, and a pressure member 220a that forms a fixing nip together with the heating member. The heating member 220b and the pressure member 220a may be any of a roller, a cylindrical film, and a belt stretched by multiple rollers. Alternatively, the heat source may be, for example, a halogen lamp that radiates heat, a ceramic heater with a heat-generating resistor pattern printed on a ceramic substrate, or an induction heating coil unit.

[0030] The image forming device 201 also includes a first discharge roller pair 225 a and a second discharge roller pair 225 b, and a duplex reversing section 201F. The first discharge roller pair 225 a and the second discharge roller pair 225 b each serve as a discharge member that discharges the sheet S, on which an image has been formed by the image forming section 201B, to a discharge space V. The duplex reversing section 201F includes a reversing roller pair 222 that is capable of reverse rotation, and a re-conveying path R through which the sheet, reversed by the reversing roller pair 222, is conveyed again toward the image forming section 201B.

[0031] An operation section 730 is provided as a user interface for receiving operations from the user in the upper portion of the image forming apparatus 201. The operation section 730 includes a display section such as a liquid crystal panel that displays information to the user using an image (screen display), and an input section such as buttons and a touch panel that allows the user to input setting information and instructions to the image forming apparatus 201.

[0032] (Image Forming Operation)

[0033] Next, a series of operations (image forming operations) in which the image forming apparatus 201 forms images on sheets S while conveying the sheets S one by one will be described. When the control section 100 receives an instruction (print instruction) to execute an image forming operation and image data, the control section 100 starts a series of tasks (image forming jobs, print jobs) in which the image forming operation is repeatedly executed for a number of sheets S specified by the user. Hereinafter, the flow of the image forming operation for a single sheet S will be described.

[0034] During the image forming operation, each photosensitive drum 212 and the intermediate transfer belt 216 are rotationally driven at a predetermined circumferential surface speed (process speed). Each charging roller 213 uniformly charges the surface of the corresponding photosensitive drum 212 to a predetermined polarity and potential by applying a charging voltage. The control unit 100 analyzes the received image data and generates a time series signal (video signal) for driving the laser scanner 210. The laser scanner 210 uses a laser beam to expose each photosensitive drum 212 based on the video signal sent from the control unit 100. As a result, an electrostatic latent image is formed on the surface of each photosensitive drum 212. This electrostatic latent image corresponds to a monochrome image of each color component decomposed into the original image data. The developing unit 214 supplies colorant to the photosensitive drum 212 and develops the electrostatic latent image into a toner image. As a result, a toner image is formed as a monochrome image on the photosensitive drum 212 in each process cartridge 211.

[0035] By applying a voltage to the primary transfer roller 219, the toner image formed on each photosensitive drum 212 is primarily transferred to the intermediate transfer belt 216. At this time, by overlapping the toner images of four colors, a full-color toner image is formed on the intermediate transfer belt 216. The full-color toner image is carried by the intermediate transfer belt 216 and conveyed toward the secondary transfer portion 201D.

[0036] In parallel with the formation of the toner image by the image forming section 201B as described above, sheets S are fed one by one toward the image forming section 201B from any one of the cassette feeding section 230, the manual feeding section 235, and the optional feeding device 500. The fed sheets S are conveyed to the secondary transfer section 201D after being subjected to tilt correction by a registration roller pair (registration roller pair 240). In the secondary transfer section 201D, the toner image is secondarily transferred from the intermediate transfer belt 216 to the sheet S by applying a voltage to the secondary transfer roller 217.

[0037] Next, the sheet S to which the toner image has been transferred is conveyed to the fixing section 201E. The fixing section 201E heats and pressurizes the toner image on the sheet S while holding and conveying the sheet S in the fixing nip between the pressure member 220a and the heating member 220b, thereby fixing the toner image to the sheet S. The sheet S that has passed through the fixing section 201E is discharged to the discharge space V by the first discharge roller pair 225a or the second discharge roller pair 225b and stacked on the stacking portion 223 (discharge tray) provided at the bottom of the discharge space V (on the upper surface of the apparatus main assembly 201A). Incidentally, when images are formed on both sides of the sheet S, the sheet S with the image formed on the first side is reversed by the reversing roller pair 222 and conveyed again to the registration roller pair 240 via the re-conveying path R. And after an image is formed on the second side of the sheet S by passing through the secondary transfer portion 201D and the fixing nip, the sheet S is discharged to the discharge space V by the first discharge roller pair 225 a or the second discharge roller pair 225 b and is stacked on the stacking portion 223 .

[0038] When forming images on a plurality of sheets S in a single print job, the plurality of sheets S are continuously fed from any one of the cassette feeding portion 230, the manual feeding portion 235, and the optional feeding device 500. The above-described image forming operation is performed for each continuously fed sheet S.

[0039] In addition to image formation for a user-specified number of sheets, a print job also includes preparatory operations before the first image formation operation and adjustment operations to place the device in a standby or stopped state after the image formation operation is completed. Preparatory operations before image formation (also known as pre-rotation) include, for example, cleaning the photosensitive drum 212 and intermediate transfer belt 216, preheating the fixing unit 201E, and adjusting various types of voltages used in the electrophotographic process. Adjustment operations after image formation (also known as post-rotation) include, for example, cleaning the photosensitive drum 212 and intermediate transfer belt 216 and terminating various types of voltage output.

[0040] In addition, after the image forming operation for the first sheet S in the print job is started, if the control section 100 detects the exhaustion of the sheet S or a conveyance defect (paper jam), the execution of the print job can be interrupted. The exhaustion of the sheet S refers to the detection of the absence of a sheet S in the feed section (230, 235, 500) selected as the supply source of the sheet S by a sheet presence / absence sensor that detects the presence or absence of the sheet S. In addition, for example, if one or more sheet sensors disposed along the conveyance path in the image forming apparatus 201 do not detect the passage of the sheet S at a prearranged timing, the control section 100 detects the occurrence of a paper jam.

[0041] The control section 100, which detects the exhaustion of the sheets S or the occurrence of a conveyance defect (a paper jam), interrupts the image forming operation being performed, stops the feeding of the next sheet S, and issues a warning to the user via the operation section 730, etc. Thereafter, when the control section 100 determines that the print job can be resumed by performing replenishment of the sheets S or clearing the paper jam, the control section 100 resumes the print job.

[0042] (Feeding equipment optional)

[0043] The optional feeding device 500 in this embodiment is an example of a sheet feeding device provided with an air blowing portion (air loosening mechanism) that loosens a sheet stack by blowing air. Loosening a sheet stack means reducing close contact between sheets and promoting their separation. Hereinafter, the following will be mainly used. Figure 3 and Figure 4 The configuration of the optional feeding device 500 will be described.

[0044] Figure 3 is a schematic diagram illustrating the internal configuration of the optional feeding device 500. Figure 4 5 is a schematic diagram illustrating a cross section of the optional feeding device 500 in a plane perpendicular to the sheet feeding direction Df.

[0045] like Figure 3 and Figure 4As shown in FIG, the optional feeding device 500 includes a storage device 510 ( Figure 1 ), a feeding unit 500F as a feeding member for feeding the sheet S, a conveying roller pair 504 ( Figure 1 ) and air blowing portions 511S and 512S. The storage device 510 and the optional feeding device 500 may be referred to as a feeding board or a board feeding device.

[0046] The feeding unit 500F includes a pickup roller 501 (first roller) and separation conveying portions (502 and 503) as a feeding member. The pickup roller 501 is disposed above the elevator plate 514. The pickup roller 501 rotates while contacting the upper surface of the uppermost sheet S of the sheet stack stacked on the elevator plate 514, thereby feeding the uppermost sheet S from the storage device 510 toward the sheet feeding direction Df.

[0047] The separation conveying section in this embodiment is a roller pair consisting of a feed roller 502 (second roller) and a retard roller 503 (third roller). The feed roller 502 is disposed downstream of the pickup roller 501 in the sheet feeding direction Df and further conveys the sheet S received from the pickup roller 501 in the sheet conveying direction Df. The retard roller 503 contacts the feed roller 502 and forms a separation nip portion together with the feed roller 502. A driving force in the direction opposite to the sheet feeding direction Df is input to the retard roller 503 via a torque limiter (i.e., the retard roller 503 is driven with a delay).

[0048] The storage device 510 includes a lifter plate 514 that can be raised and lowered and on which the sheets S are stacked, restriction members (511, 512, and 513) that restrict the positions of the sheets S, and a storage device body 510A ( Figure 1 ). The lifter plate 514 is a support portion that supports the sheet bundle. The lifter plate 514 is housed in the storage device body 510A and is configured to be controlled to be raised and lowered based on the position of the upper surface of the sheet bundle using, for example, a wire drum-type raising / lowering mechanism. The limiting member includes a pair of side end limiting plates 511 and 512 that limit the position of the end portions (side ends) of the sheet S in the sheet width direction Dw perpendicular to the sheet feeding direction Df, and a rear end limiting plate 513 that limits the position of the rear end of the sheet S in the sheet feeding direction Df.

[0049] The side end restriction plates 511 and 512 are arranged in the sheet width direction Dw relative to the conveying center Sc ( Figure 4) on one side and the other side. For example, the conveying center Sc is the center position in the sheet width direction Dw of the contact area where the pickup roller 501 contacts the sheet S. The side end limiting plates 511 and 512 are connected via an interrelated mechanism such as a rack and pinion, and are configured to move in relation to each other to maintain a symmetrical positional relationship relative to the conveying center Sc. In addition, the rear end limiting plate 513 is also configured to be able to adjust the position according to the length of the sheet S in the sheet feeding direction Df. Incidentally, the position of the front end of the sheet S in the sheet feeding direction Df is limited by the wall surface of the storage device body 510A.

[0050] The air blowing portion 511S includes a fan 511b, a blowing nozzle 511a, and a floating suppressor 511c. Similarly, the air blowing portion 512S includes a fan 512b, a blowing nozzle 512a, and a floating suppressor 512c.

[0051] The air blowing sections 511S and 512S in this embodiment are arranged to blow air toward the side ends of the sheet bundle stacked on the lifter plate 514. In this embodiment, one air blowing section 511S is incorporated into one side end restriction plate 511, and the other air blowing section 512S is incorporated into the other side end restriction plate 512. In other words, the fans 511b, 512b, etc., which are components of the air blowing sections 511S and 512S, move integrally with the side end restriction plates 511 and 512. Incidentally, the air blowing sections 511S and 512S may also be arranged in a configuration independent of the side end restriction plates 511 and 512.

[0052] Fans 511b and 512b include blade members that generate air flows (A1, A2) by being rotated and a motor portion that rotationally drives the blade members. For fans 511b and 512b, for example, a multi-blade fan with excellent quietness can be used, however, other fans such as axial flow fans can also be used.

[0053] The air blowing nozzles 511a and 512a are openings provided to the restriction surfaces (surfaces opposite to the side ends of the sheet bundle) of the side end restriction plates 511 and 512. The air blowing nozzle 511a is connected to the blowing outlet of the fan 511b via a flow path formed inside the side end restriction plate 511. Similarly, the air blowing nozzle 512a is connected to the blowing outlet of the fan 512b via a flow path formed inside the side end restriction plate 512.

[0054] The floating suppressors 511c and 512c are disposed so as to protrude inward (on the conveying center Sc side) from the limiting surfaces of the side end limiting plates 511 and 512 in the sheet width direction Dw. The floating suppressors 511c and 512c have a function of preventing stacking defects caused by the sheet S floating due to the blowing of air passing over the side end limiting plates 511 and 512.

[0055] In addition, if Figure 2 As shown in , the optional feeding device 500 includes the control portion 100 , a feeding motor 520 , a conveying motor 521 , a feeding sensor 505 , a sheet presence / absence sensor 506 , and an environmental sensor 522 .

[0056] The control section 100 functions as a control unit that controls the operation of the optional feeding device 500. The control section 100 includes a ROM 102 that stores a program, a CPU 101 that reads out the program from the ROM 102 and executes the program, and a RAM 103 that provides a work area for the CPU 101. The CPU 101 controls the operation of the fans 511b and 512b and each motor (520 and 521) according to the program. The control section 100 operates according to the flow described below ( Figure 5 ) implements the operation of the optional feeding device 500.

[0057] The environmental sensor 522 is a detection component for detecting the environmental conditions surrounding the space in which the optional feeding device 500 or the image forming apparatus 201 is installed. The environmental sensor 522 in this embodiment can obtain information on the temperature (ambient temperature) and relative humidity (ambient humidity) surrounding the optional feeding device 500 as environmental conditions. The control section 100 can perform control depending on the environmental conditions based on the detection results of the environmental sensor 522.

[0058] The feed sensor 505 is a sensor for detecting the separation of the nip portion and the conveying roller pair 504 ( Figure 1 ). The control section 100 can monitor whether feeding of the sheet S is correctly performed based on the detection result of the feeding sensor 505. The sheet presence / absence sensor 506 is a sensor (sheet detection member) that detects the presence / absence of the sheet S in the lifter plate 514.

[0059] In addition, the control section 100 can also acquire information related to the attributes of the sheet S set in the storage device 510 (hereinafter referred to as "sheet information"), for example, from a user input via the operation section 730. The sheet information may be a combination of one or more selected from the group consisting of the size of the sheet S, the basis weight, the presence or absence of surface treatment, and the brand name.

[0060] Incidentally, part or all of the functions of the control section 100 described below may be implemented by a control circuit disposed outside the optional feeding device 500. That is, at least a part of the control section 100 for controlling the operation of the optional feeding device 500 may be outside the optional feeding device 500. In this case, the "sheet feeding device" is constituted by the optional feeding device 500 and the control circuit for controlling the optional feeding device 500.

[0061] (Basic operation of optional feeding equipment)

[0062] The optional feeding device 500 performs a feeding operation in which the feeding unit 500F feeds the sheets S while separating them one by one, and an air blowing operation (air loosening operation) in which the air blowing portions 511S and 512S blow air toward the sheet bundle to loosen the sheets.

[0063] The feeding operation is started by rotationally driving the pickup roller 501 in a state where the pickup roller 501 is in contact with the uppermost sheet S on the elevator plate 514. By the rotation of the pickup roller 501, the uppermost sheet S is fed in the sheet feeding direction Df and is further separated into individual sheets in the separation nip. That is, by applying a friction force to the sheet S passing through the separation nip in a direction opposite to the sheet feeding direction Df, the delay roller 503 prevents multiple sheets S from passing through the separation nip (overlapping feeding, double feeding). In addition, in the case where only a single sheet S passes through the separation nip, the delay roller 503 rotates following the feed roller 502 and the sheet S due to the sliding of the torque limiter. The sheet S that has passed through the separation nip is conveyed toward the main assembly 201A of the device by the conveying roller pair 504.

[0064] The air blowing operation is started by starting the fans 511b and 512b and is completed by stopping the fans 511b and 512b. Figure 4 As shown in the air flow lines A1 and A2 in FIG, air is blown from the blowing nozzles 511a and 512a toward the side ends of the sheet stack. As the air enters the spaces between the sheets S, an upward force acts on the upper sheet S in the sheet stack, and the adsorption force between the sheets (close contact between the sheets) is reduced. By reducing the adsorption force between the sheets, for example, even when using coated paper that tends to have a large adsorption force between the sheets, the feed unit 500F can easily convey the sheets S one by one without experiencing sheet S separation problems.

[0065] (Control Method)

[0066] In the following, we will Figure 5The control method of the optional feeding device 500 according to the present embodiment is described by referring to the flowchart in FIG. For example, the control section 100 starts the processing of this flow when a print job is input. Hereinafter, unless otherwise specifically described, each step in this flow is performed by the control section 100 ( Figure 2 )implement.

[0067] The control section 100 determines whether an air blowing operation is performed when a print job starts (S3 to S5) (S1). If the air blowing operation is performed, the operating conditions of the air blowing operation are set based on the environmental conditions detected by the environmental sensor 522 or the like.

[0068] In this embodiment, if the sheet S used in the current print job is coated paper, the environmental condition is a high temperature and high humidity environment or a normal environment and any one of the following conditions applies, the control part 100 determines to perform the air blowing operation at the start of the print job ("Yes" in S1).

[0069] a) At the start of the current print job, if a predetermined time τ (described below) has elapsed since the last air blowing operation was performed.

[0070] b) If the control portion 100 determines that replenishment of sheets of the storage device 510 is performed or may be performed from the completion of the previous print job until the start of the current print job.

[0071] On the other hand, if the sheet S used in the current print job is not coated paper (e.g., plain paper), or if the environmental conditions are a low-temperature, low-humidity environment, the control section 100 determines not to perform the air blowing operation at the start of the print job ("No" in S1). Furthermore, even if coated paper is used and the environmental conditions are satisfied, if a) or b) above does not apply, the control section 100 also determines not to perform the air blowing operation at the start of the print job ("No" in S1).

[0072] Incidentally, the above is merely an example of a determination method. The control section 100 may be configured to execute the air blowing operation if it determines that the sheets are in close contact (relatively strong suction between the sheets), and not execute the air blowing operation if it determines that the sheets are not in close contact (relatively weak suction between the sheets). For example, in addition to a) and b) above, if the supply source of the sheets S in the previous print job was not the optional feeding device 500, and the supply source of the sheets S in the current print job is the optional feeding device 500, the air blowing operation may be executed.

[0073] In this embodiment, the operating conditions of the air blowing operation include the number of rotations of the fans 511b and 512b corresponding to the amount of air blown, and the length of time the fans 511b and 512b are rotated (referred to as the blowing time). Table 1 below shows the classification of environmental conditions, representative values ​​of temperature and humidity, and the set values ​​of the number of rotations and blowing time of the fans 511b and 512b in this embodiment. The number of rotations of the fans 511b and 512b is expressed as a duty cycle in the PWM control used to control the input power to the fans 511b and 512b.

[0074] [Table 1]

[0075]

[0076] As shown in Table 1 above, in a high-temperature, high-humidity environment, the air blowing volume increases and the blowing time is prolonged compared to a normal environment. In other words, because the absolute moisture content in the air surrounding the optional feeding device 500 is high, the control unit 100 increases the intensity of the air blowing operation. That is, the air blowing volume when the absolute moisture content is a first content (e.g., a content corresponding to 30°C / 80% RH) is greater than the air blowing volume when the absolute moisture content is a second content (e.g., a content corresponding to 23°C / 50% RH) which is less than the first content. In addition, the blowing time when the absolute moisture content is the first content is longer than the blowing time when the absolute moisture content is the second content which is less than the first content.

[0077] Incidentally, in this embodiment, it is defined that a high temperature and low humidity environment (eg, 30°C / 10%RH) is classified as a low temperature and low humidity environment, and a low temperature and high humidity environment (eg, 15°C / 80%RH) is classified as a normal environment.

[0078] Based on the above settings, in S3, the control section 100 starts the fans 511b and 512b and starts the air blowing operation. Figure 4 As shown in FIG, several to several dozen sheets S in the upper portion of the sheet stack on the lifter plate 514 float, and the suction force between the sheets decreases. Furthermore, the floating suppressors 511 c and 512 c restrict the sheets S from floating due to the air from passing over the side end restriction plates 511 and 512. If the blowing time set in S2 has elapsed since the fans 511 b and 512 b were activated ("Yes" in S4), the control unit 100 stops the fans 511 b and 512 b and completes the air blowing operation (S5).

[0079] It will be described that by performing the air blowing operation at the start of the print job and performing the feeding operation (S8) after the air blowing operation is completed, it becomes possible to reduce the possibility of the oblique movement of the sheet S occurring due to the action of the air. Figure 9 As shown in , when the feeding operation is started in parallel with the air blowing operation, a bend occurs in the sheet S as it floats, and when the side ends of the sheet S leave the side end restriction plates 511 and 512, the tilting movement suppression effect of the side end restriction plates 511 and 512 is weakened. Furthermore, due to assembly tolerances or design reasons, the contact positions C1 and C2 (the points at which the contact load acts on the sheet S) of the pickup roller 501 and the feed roller 502 in the sheet width direction Dw may be misaligned. In this case, if a difference in conveying speeds V1 and V2 (V1 > V2) occurs between the pickup roller 501 and the feed roller 502 due to, for example, resistance from the sheet S from a conveying guide, a force is generated that causes the sheet S to rotate counterclockwise in the figure. Furthermore, a rotational force may be generated due to misalignment between the roller contact positions C1 and C2 and the conveying center Sc. In contrast, in this embodiment, since the feeding operation (S8) is performed while the air blowing operation is stopped, tilting movement of the sheet S can be suppressed.

[0080] The control portion 100 starts counting the elapsed time T while the fans 511b and 512b are stopped (S6). The elapsed time T represents the length of time that has passed without performing an air blowing operation since the last air blowing operation was completed.

[0081] As the elapsed time T increases, air escapes from under the sheets S that were floated by the previous air blowing operation. Although the suction force between the sheets gradually increases as the air escapes, the feeder unit 500F can feed the sheets while separating the sheets S one by one unless the suction force exceeds the separation capability of the feeder unit 500F. However, if the suction force becomes strong enough to exceed the separation capability of the feeder unit 500F, a separation defect may occur.

[0082] If the elapsed time T since the last air blowing operation was completed is the predetermined time τ or less ("YES" in S7), the control section 100 starts the next feeding operation (S8). The start of the feeding operation means that the pickup roller 501 is rotated by the driving force of the feeding motor 520 while the pickup roller 501 is in contact with the uppermost sheet S. After the feeding operation is started, the separation of the sheet S in the separation nip and the conveyance of the sheet S by the conveying roller pair 504 are performed as described above. The value of the predetermined time τ is stored in the ROM 102 as a preset value, for example, and is read out by the CPU 101.

[0083] Until the number of sheets S specified by the user when inputting the print job is fed ("No" in S9), the control section 100 returns the process to S7 and repeats the same process. In other words, until a predetermined time τ has elapsed since the last completion of the air blowing operation ("Yes" in S7), the control section 100 repeatedly performs the feeding operation (S8) until the specified number of sheets S are fed. If the feeding of the specified number of sheets S is completed before the predetermined time τ has elapsed since the last completion of the air blowing operation ("Yes" in S9), the control section 100 completes the processing of this flow.

[0084] On the other hand, if the elapsed time T since the last air blowing operation was completed in S7 exceeds the predetermined time τ ("No" in S7), the control section 100 returns the process to S3 without performing the next feeding operation and performs the air blowing operation again (S3 to S5). As a result, several to several dozen sheets S in the upper portion of the sheet bundle on the lifter plate 514 float, and the suction force between the sheets decreases again. When the blowing operation is completed, the control section 100 resets the elapsed time T and starts a new count.

[0085] In this manner, when the control section 100 executes a job of feeding a specified number of sheets, the control section 100 (1) repeats the feeding operation until a predetermined time τ has elapsed since the completion of the previous blowing operation, and (2) repeats the following operation: when the predetermined time τ has elapsed since the completion of the previous blowing operation, the feeding operation is stopped and the blowing operation is performed again until the feeding of the specified number of sheets is completed. In this manner, by executing the air blowing operation at intervals of the predetermined time τ, it becomes possible to suppress separation defects of the sheets S.

[0086] Here, in Figure 6 , there is shown an example of transition of the adsorption force between sheets with respect to the time in which the sheets are retained in the sheet bundle after the adsorption force between the sheets is reduced once. Figure 8 As shown in , the adsorption force is represented by a force F (unit: gf) in the sheet feeding direction Df, which is required to move the uppermost sheet S in the sheet bundle St in the sheet feeding direction Df to peel the uppermost sheet S from the underlying sheets. Figure 6 The measurement was performed at a temperature of 30° C. and a humidity of 80% RH, which correspond to the above-mentioned high-temperature and high-humidity environment. Figure 6 The horizontal axis in the figure represents the time elapsed from the start of the placement, where the basis weight is 200 g / m 2 The coated papers are pulled apart one by one, stacked in a state of a sheet stack St, and left. Figure 6 The vertical axis in the figure represents the time when the elapsed time is the preset time. Figure 8The magnitude of the adsorption force is measured by the method in .

[0087] like Figure 6 As shown in , the adsorption force between the sheets increases monotonically from the start of leaving until a time of about 300 seconds has passed, and becomes approximately constant in magnitude thereafter. Therefore, when the adsorption force between the sheets, which becomes stronger as time T has passed after the most recent air blowing operation is completed, exceeds the separation capability (separation limit adsorption force) of the feeding unit 500F, a separation defect of the sheet S may occur during the feeding operation. The separation limit adsorption force is the maximum value of the adsorption force between the top sheet S and the sheet S below, at which the feeding unit 500F can separate the top sheet S from the sheet S below and feed the top sheet S. In other words, the separation limit adsorption force is the maximum value of the adsorption force permissible during the feeding operation. The separation limit adsorption force may vary depending on the permissible torque of the torque limiter provided in the delay roller 503, the friction coefficient between the sheets, the respective friction coefficients between the feed roller 502 and the delay roller 503 and the sheet S, and the like.

[0088] Figure 7 The segment from 0 seconds to 180 seconds is extracted from the curve graph, which can be considered as Figure 6 The section where the adsorption force increases monotonically. Figure 7 The dot-dash line A in FIG shows an example of the separation limit adsorption force. In this embodiment, the separation limit adsorption force is set to 228 gf.

[0089] Through Figure 7 Applying linear approximation to the graph in , the relationship between the adsorption force (y) and the elapsed time (x) can be expressed by the following equation (1).

[0090] y = 2.0909x + 116.06 ... (1)

[0091] From the above equation (1), it can be seen that in this embodiment, the adsorption force between the sheets exceeds the separation limit adsorption force about 53 seconds after the start of the leaving. In other words, when a print job is executed using the same coated paper and environmental conditions as in the above test, even if the air blowing operation is performed at the start of the job, a separation defect of the sheets S may occur in the feeding operation after the elapsed time T after the completion of the air blowing operation exceeds 53 seconds.

[0092] Therefore, in this embodiment, a predetermined time τ is set in advance, which is shorter than the elapsed time when the suction force between the sheets reaches the separation limit suction force. When the elapsed time T from the completion of the last air blowing operation exceeds the predetermined time τ, the feeding operation is interrupted, the air blowing operation is performed ("No" in S7, then S3 to S5), and the feeding operation is restarted after the air blowing operation is completed (S8).

[0093] In other words, after performing a blowing operation, if the predetermined time τ has not elapsed since the last blowing operation, the control section 100 performs a feeding operation while the blowing operation is stopped. Alternatively, if the predetermined time τ has elapsed since the last air blowing operation, the control section 100 stops the feeding operation, performs the blowing operation again, and then resumes the feeding operation after the blowing operation is completed again. Thus, since the feeding operation is performed while the suction force between the sheets does not exceed the separation limit suction force, it is possible to suppress separation defects of the sheets S.

[0094] In other words, according to the present embodiment, the object of providing a sheet feeding device and an image forming apparatus capable of suppressing the occurrence of separation defects of sheets is achieved.

[0095] Figure 10 , which is a comparative example with respect to the present embodiment, shows a control method for the optional feeding device 500. In this comparative example, after the air blowing operation (S101 to S103) is performed at the start of a print job, the feeding operation (S104, S105) is repeated while the air blowing operation is stopped. In this comparative example, even if the time after the completion of the air blowing operation becomes long, the air blowing operation is not performed again.

[0096] According to this comparative example, since the feeding operation is performed while the air blowing operation is stopped, the occurrence of tilting movement due to the action of air can be reduced, as in the embodiment of the present invention. However, in this comparative example, even after the elapsed time after the completion of the air blowing operation exceeds the predetermined time τ, the feeding operation (S104) is repeated until the number of sheets S specified by the job has been fed. Therefore, the feeding operation is performed while the suction force between the sheets exceeds the separation limit suction force, resulting in the possibility of separation defects of the sheets S.

[0097] In contrast, according to this embodiment, the feeding operation is interrupted before the suction force between the sheets exceeds the separation limit suction force, and the feeding operation is restarted after the air blowing operation is performed. As a result, it is possible to reduce the occurrence of tilting movement caused by the action of air, and the possibility of separation defects of the sheets S can be reduced.

[0098] Furthermore, according to this embodiment, regardless of the number of sheets fed by the feeding unit 500F since the completion of the last blowing operation, the blowing operation is resumed based on the fact that the elapsed time T from the completion of the last blowing operation exceeds the predetermined time τ. In other words, suppose that, in the event that a print job is interrupted and then resumed for some reason, the elapsed time from the completion of the last blowing operation performed before the job was interrupted until the job is resumed exceeds the predetermined time τ. In this case, even if the number of sheets fed from the completion of the last blowing operation to the interruption of the job is small, when the job is resumed, feeding of the sheets S is resumed after the blowing operation is performed.

[0099] Therefore, even if the suction force between the sheets exceeds the separation limit suction force during the print job interruption period, when the print job is resumed, the feeding of the sheets S is resumed with the suction force reduced by the blowing operation. Therefore, compared to a configuration in which the timing of the blowing operation is determined based on the number of sheets fed, for example, it becomes possible to execute the blowing operation at a more appropriate timing. Incidentally, causes of print job interruption include conveyance defects (paper jams), depletion of toner, depletion of sheets S, and interruption instructions from the user.

[0100] In addition, Figure 5 In S1 of the process, according to step a) above, if the time elapsed from the execution of the air blowing operation in the previous job until the start of the current job does not exceed the predetermined time τ, the feeding operation is started at the start of the current job without performing the air blowing operation. In other words, when a second job is executed after a first job, if the time elapsed from the completion of the previous air blowing operation performed during the execution of the first job until the start of the second job does not exceed the predetermined time, the control section 100 starts the feeding operation at the start of the second job without performing the air blowing operation. In this way, by starting the feeding of the sheet S in the current print job without performing the air blowing operation while the release effect of the air blowing operation in the previous print job remains, it becomes possible to improve the productivity of the optional feeding device 500.

[0101] Incidentally, the control can be simplified, and the configuration can be such that the air blowing operation is always performed at the start of a print job, and then the feeding operation is started. Alternatively, for example, the configuration can be such that the air blowing operation is performed at the start of the current print job only when the environmental conditions have changed between the start of the previous print job and the start of the current print job.

[0102] In determining Figure 5When the necessity of the air blowing operation (S1) in the flow is determined in accordance with b) above, if replenishment of sheets S is being performed, the air blowing operation is performed even if the elapsed time T has not exceeded the predetermined time. In other words, after the sheet presence / absence sensor 506 (sheet detection component) detects the absence of sheets in the lifter plate 514 (support portion), if the sheet presence / absence sensor 506 detects the presence of sheets in the lifter plate 514, the control section 100 starts the feeding operation after the air blowing operation is performed, even if the predetermined time τ has not yet elapsed since the completion of the previous air blowing operation. Since the sheet bundle newly stacked on the lifter plate 514 is likely to be in a state where the suction force between the sheets is strong, by executing the above control, it becomes possible to suppress separation defects in the feeding operation after replenishment of the sheet bundle.

[0103] By the way, in Figure 5 In the description of FIGURE 5, the determination of whether to execute the air blowing operation at the start of a job is made based on the detection result of the sheet presence / absence sensor 506. However, the same control can be performed even when the sheet presence / absence sensor 506 detects the absence of a sheet during job execution. In other words, assume the following situation: during job execution, the sheet presence / absence sensor 506 detects the absence of a sheet and the job is interrupted. Then, the user replenishes the sheet S, and the sheet presence / absence sensor 506 detects the presence of a sheet. In this case, even if the predetermined time τ has not elapsed since the previous air blowing operation was completed, the control section 100 resumes the feeding operation after the air blowing operation is executed.

[0104] Furthermore, the method for executing the air blowing operation when sheets S may be replenished (exchanged) is not limited to the method using the detection result of the sheet presence / absence sensor 506. For example, if the image forming apparatus 201 is in sleep mode between the completion of the previous job and the input of the current job, the control section 100 may determine that sheets S may have been replenished (exchanged) and execute the air blowing operation at the start of the current job. Similarly, if, for example, the opening / closing detection sensor provided to the storage device 510 detects the opening / closing of the storage device 510 between the completion of the previous job and the input of the current job, the control section 100 may determine that sheets S may have been replenished (exchanged).

[0105] (Setting Example of Predetermined Time τ)

[0106] In the present embodiment, the value of the predetermined time τ defining the time interval of the air blowing operation is set to different values ​​depending on the environmental conditions when the print job starts and the sheet information about the sheets S used for the print job.

[0107] By selecting a value for the predetermined time τ from a plurality of values, it is possible to achieve both suppression of sheet S separation defects and improvement in productivity. In other words, compared to a case where the predetermined time τ is always set to the same value (a value that suppresses sheet S separation defects regardless of conditions), under conditions where the increase in the suction force between the sheets is relatively slow, the predetermined time τ can be increased, and the frequency of air blowing operations can be reduced. This improves the productivity of the optional feeding device 500 (the number of sheets fed relative to the time elapsed from the start of a print job). Furthermore, it is possible to improve the productivity of the image forming apparatus 201 (the number of sheets of an image output relative to the time elapsed from the start of a print job). Below, an example of setting the predetermined time τ will be described.

[0108] First, an example of setting the predetermined time τ depending on the environmental conditions will be described. As described above, in the present embodiment, the operating conditions of the air blowing operation vary depending on the environmental conditions. This is because, even in the case of the same type of sheet S, the maximum value of the adsorption force between the sheets varies depending on the environmental conditions. Similarly, the transition of the adsorption force corresponding to the elapsed time after the adsorption force between the sheets is reduced due to the air blowing operation also varies depending on the environmental conditions. Therefore, in each of the "high temperature and high humidity environment" and the "normal environment" subjected to the air blowing operation, the transition of the adsorption force between the sheets corresponding to the elapsed time after the air blowing operation is checked, and an appropriate value of the predetermined time τ is predetermined. As an example, the value of the predetermined time τ for each environmental classification of coated paper (hereinafter, coated paper 1) is determined as follows.

[0109] [Table 2]

[0110] Environmental classification Scheduled time τ High temperature and high humidity environment 30 seconds Normal environment 240 seconds

[0111] According to the above example, the interval between air blowing operations in a high temperature and high humidity environment is shorter than the interval between air blowing operations in a normal environment. In other words, the predetermined time τ (30 seconds) when the absolute moisture content is a first content (e.g., a content corresponding to 30°C / 80% RH) is shorter than the predetermined time τ (240 seconds) when the absolute moisture content is a second content lower than the first content (e.g., a content corresponding to 23°C / 50% RH).

[0112] Thus, by performing the air blowing operation at a high frequency in a high-temperature and high-humidity environment in which the adsorption force between the sheets increases relatively quickly, it becomes possible to suppress separation defects of the sheets S. In addition, by performing the air blowing operation at a low frequency in a normal environment in which the adsorption force between the sheets increases relatively slowly, it becomes possible to improve the productivity of the optional feeding device 500.

[0113] Next, we will describe an example of setting the predetermined time τ depending on the type of sheet S. In this embodiment, coated paper is classified into the following three types based on its basis weight, and a value for the predetermined time τ is set for each type. The control section 100 selects an appropriate value for the predetermined time τ based on the type of sheet S used in the print job.

[0114] [Table 3]

[0115]

[0116] The ease of increasing the adsorption force between the sheets depends on the physical property values ​​of the sheet S. The physical property values ​​of the sheet S include, for example, permeability (ease of air permeation), smoothness (surface smoothness), and hardness (ease of deformation). Therefore, it is preferable to examine the ease of increasing the adsorption force for each type of sheet S and predetermine the value of the predetermined time τ.

[0117] According to the above example, the execution interval between the air blowing operations in the case of using "coated paper 3" having a large basis weight is shorter than the execution interval between the air blowing operations in the case of using "coated paper 1" having a small basis weight. In other words, when the basis weight is the first value (for example, 240 g / m 2 ) is greater than the predetermined time τ (220 seconds or 20 seconds) when the basis weight is a second value smaller than the first value (e.g., 120 g / m 2 ) is short in the case of the scheduled time τ (240 seconds).

[0118] Thus, by performing the air blowing operation at a high frequency when using the "coated paper 3" which is relatively easy to increase the adsorption force between the sheets, it becomes possible to suppress separation defects of the sheets S. In addition, by performing the air blowing operation at a low frequency when using the "coated paper 1" which is relatively easy to increase the adsorption force between the sheets, it becomes possible to improve the productivity of the optional feeding device 500.

[0119] Furthermore, the adsorption force between sheets is also affected by sheet size, with larger sheets increasing the more readily. Therefore, as sheet size increases, the predetermined time τ is preferably shortened. In other words, the predetermined time τ when using sheets S of a first size (e.g., A3 size) is shorter than the predetermined time τ when using sheets of a second size (e.g., B4 size) with a smaller area than the first size.

[0120] Thus, by performing the air blowing operation at a high frequency when using the sheets S of the first size in which it is relatively easy to increase the adsorption force between the sheets, it becomes possible to suppress separation defects of the sheets S. In addition, by performing the air blowing operation at a low frequency when using the sheets S of the second size in which it is relatively easy to increase the adsorption force between the sheets, it becomes possible to improve the productivity of the optional feeding device 500.

[0121] Incidentally, it is also desirable to vary the operating conditions of the air blowing operation depending on the sheet type and sheet size. For example, when using "coated paper 3," it is expected that the fan rotation frequency will increase and the blowing time will be extended compared to when using "coated paper 1." Furthermore, when using sheets S of a first size, it is expected that the fan rotation frequency will increase and the blowing time will be extended compared to when using sheets S of a second size. This makes it possible to more reliably reduce the suction force between sheets with a single air blowing operation.

[0122] (Variation)

[0123] In the above-described embodiment, the optional feeding device 500 is described as an example of a sheet feeding device. However, the present technology is not limited thereto, but can be applied to any sheet feeding device provided with an air blowing portion (air release mechanism), for example, any one of the cassette feeding portion 230 and the manual feeding portion 235. In addition, it is not limited to a sheet feeding device that feeds a sheet S as a recording medium toward the image forming portion 201B. For example, the present technology can be applied to a sheet feeding device that feeds a sheet S as an original in an image reading device, or a sheet feeding device that feeds a sheet S that has been sorted in a sheet type sorting device.

[0124] The feeding mechanism composed of the pickup roller 501, the feed roller 502, and the retard roller 503 described in the above embodiment is an example of the feeding unit 500F that feeds the sheets S one by one. For example, a belt conveyor type feeding unit that sucks the individual sheets S onto a feed belt by negative pressure generated by a fan and conveys the sheets S may be used. In addition, the retard roller 503 is an example of a separating member that performs separation of the sheets S, and, for example, an elastic member having a pad shape that contacts the feed roller 502 may be used as the separating member.

[0125] In the above embodiment, the method of using the value of the predetermined time τ set in advance depending on the environmental conditions and sheet information is exemplified. However, this is not limiting, and for example, the user may arbitrarily set the value of the predetermined time τ via the operation portion 730 .

[0126] In addition, in the above-described embodiment, the value of the predetermined time τ is determined based on the environmental conditions at the start of the print job, and the value of the predetermined time τ is not changed for the print job. However, this is not limited to this. For example, in the case where the elapsed time T from the last air blowing operation exceeds the predetermined time τ, the environmental conditions are determined again based on the detection result of the environmental sensor 522, and the value of the predetermined time τ may be updated. In other words, Figure 5 In the flow in, it can be configured so that in the case of "No" in S7, the process can return to S2. When a print job is executed over a long period of time, or when the image forming apparatus 201 is installed in a place where changes in environmental conditions are significant, this modification may be advantageous.

[0127] (Other embodiments)

[0128] The present invention may also be implemented by supplying a program that implements one or more functions of the above-described embodiments to a system or device via a network or storage medium, and having one or more processors in a computer of the system or device read and execute the program. Alternatively, the present invention may be implemented by a circuit (e.g., an ASIC) that implements the one or more functions.

[0129] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A sheet feeding device comprising: a supporting portion configured to support a sheet stack; a feeding member configured to separate and feed sheets from the sheet bundle one by one; an air blowing portion configured to blow air toward a side end of the sheet bundle; a control member configured to perform a blowing operation in which air is blown toward a side end of a sheet by the air blowing portion and a feeding operation in which the sheet is fed by the feeding member, wherein, after the execution of the blowing operation, the control component performs the feeding operation when a predetermined time has not yet passed since the completion of the blowing operation and the blowing operation is stopped, and performs another blowing operation when the predetermined time has passed since the completion of the blowing operation and the feeding operation is stopped.

2. The sheet feeding device according to claim 1 , further comprising an environmental sensor configured to detect an environmental condition surrounding the sheet feeding device, in, The control section changes the predetermined time depending on the environmental condition based on a detection result of the environmental sensor.

3. The sheet feeding apparatus according to claim 2, wherein The control section changes the predetermined time so that the predetermined time when the absolute moisture content in the air around the sheet feeding device is a first content is shorter than the predetermined time when the absolute moisture content is a second content that is lower than the first content.

4. The sheet feeding apparatus according to claim 1, wherein The control section changes the predetermined time depending on a basis weight of the sheet supported by the supporting portion.

5. The sheet feeding apparatus according to claim 4, wherein The control section changes the predetermined time so that the predetermined time is shorter when the basic weight is a first value than when the basic weight is a second value that is smaller than the first value.

6. The sheet feeding apparatus according to claim 1, wherein The control section changes the predetermined time depending on a sheet size of a sheet supported by the supporting portion.

7. The sheet feeding apparatus according to claim 6, wherein The control section changes the predetermined time so that the predetermined time is shorter when the sheet size is a first size than when the sheet size is a second size that is smaller in area than the first size.

8. The sheet feeding device according to claim 1, further comprising an operation section configured to accept an operation from a user, in, The control section determines the predetermined time based on an input from a user to the operation section.

9. The sheet feeding apparatus according to claim 1, wherein In the case where a second job of feeding sheets is performed after a first job of feeding sheets, when the elapsed time from the completion of the last blowing operation performed during the execution of the first job until the start of the second job does not exceed the predetermined time, the control component starts the feeding operation without performing the blowing operation at the start of the second job.

10. The sheet feeding apparatus according to claim 1, further comprising a sheet detecting member configured to detect the presence or absence of the sheet in the supporting portion, in, In a case where the sheet detecting component detects the presence of the sheet in the supporting portion after the sheet detecting component has detected the absence of the sheet in the supporting portion, the control component starts the feeding operation after performing the blowing operation even if the predetermined time has not elapsed since the completion of the previous blowing operation.

11. The sheet feeding apparatus according to claim 1, wherein In a case where a job of feeding a specified number of sheets is interrupted and then the job is restarted, when the elapsed time from the completion of the last blowing operation performed before the interruption of the job until the restart of the job exceeds the predetermined time, the control component starts the feeding operation after performing the blowing operation, regardless of the number of sheets fed by the feeding component until the interruption of the job.

12. The sheet feeding apparatus according to claim 1, wherein When a job of feeding a specified number of sheets is performed, the control component repeats the feeding operation from completion of the last blowing operation until the predetermined time has passed, and when the predetermined time has passed from completion of the last blowing operation, the control component repeatedly stops the feeding operation and performs another blowing operation until feeding of the specified number of sheets is completed.

13. The sheet feeding apparatus according to claim 1, wherein The feeding member includes a first roller, a second roller, and a third roller, the first roller being configured to contact an uppermost sheet and feed the sheet from the supporting portion in a sheet feeding direction, the second roller being disposed downstream of the first roller in the sheet feeding direction and configured to feed the sheet in the sheet feeding direction, the third roller being configured to form a separation nip by contacting the second roller and configured to apply a friction force in a direction opposite to the sheet feeding direction to the sheet passing through the separation nip, and The air blowing portion includes a fan configured to generate an air flow and a nozzle configured to blow the air flow toward an end portion of the sheet bundle in a sheet width direction perpendicular to the sheet feeding direction.

14. An image forming apparatus comprising: The sheet feeding device according to claim 1; as well as The image forming section is configured to form an image on a sheet fed by the sheet feeding device.

15. The image forming apparatus according to claim 14, wherein The supporting portion of the sheet feeding device is movably provided to the image forming apparatus, and The supporting portion is movable to an open position opened with respect to the image forming apparatus when a sheet is placed thereon and fed, and is movable to a closed position closed with respect to the image forming apparatus when a sheet is not placed thereon.

Images