Sheet feeder, and image forming device comprising sheet feeder

Abstract

To solve a problem that there is a risk of sheet-feeding failure occurring due to insufficient sheet separation in a sheet feeder that performs feeding by spraying air onto sheets.SOLUTION: This sheet feeder is provided with a sheet support part, a feed roller for feeding sheets, an air blowing part for blowing air toward a side end part of the sheets, detection means for detecting a feeding abnormality of the sheets, count means for counting the number of fed sheets, setting means for setting the number of sheets, and a control part for controlling an air-feeding operation. When the feeding abnormality of the sheets is detected by the detection means, the control part subtracts the number of sheets set by the setting means based on a count value obtained by the count means, and executes the air-feeding operation with the subtracted number of sheets.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device and an image forming apparatus. [Background technology]

[0002] For example, image forming apparatuses such as copiers, facsimiles, and printers are equipped with a sheet feeding device for setting a stack of sheets to be supplied to an image forming section where an image is formed. The sheet feeding device has a feeding cassette section provided at the bottom of the image forming apparatus main body, a manual feeding section provided on the side of the image forming apparatus main body, and the like.

[0003] In recent years, there has been an increasing demand for forming images on a variety of sheets, and sheets with smooth surfaces, such as coated paper, are often used as recording materials. When a stack of such smooth-surfaced sheets is set in a sheet feeding device, the sheets tend to adhere closely to each other, making it difficult to separate and feed a single sheet from the stack. For this reason, Patent Document 1 discloses a device that blows air between the sheets to lift them up and separate the sheets.

[0004] Furthermore, Patent Document 2 discloses a method for blowing air onto a stack of sheets and feeding the sheets while the sheets are in a floating state, which can cause the sheets to easily skew. Therefore, the method discloses that the air is blown for a predetermined period of time, and then the air blowing is stopped before the sheets are fed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-23747 [Patent Document 2] Japanese Patent Application Publication No. 2023-102814 Summary of the Invention [Problem to be solved by the invention]

[0006] However, because there are many types of sheets with different physical properties, the adhesive force between some sheets may be stronger than expected. As disclosed in Patent Document 2, air is blown onto a sheet stack for a predetermined time (10 seconds) while the feeding operation is stopped, and then a predetermined number of sheets (e.g., 10 sheets) are fed. If the above air blowing and feeding operation are then repeated, the predetermined number (10 sheets) of sheets may not be lifted from the sheet stack, resulting in insufficient separation. If this insufficient separation occurs, a feed jam may occur, in which the top sheet does not separate from the sheet stack during sheet feeding and does not reach a predetermined position on the conveyance path within the image forming apparatus within the predetermined time. Furthermore, a multi-feed jam may occur, in which the top sheet and the sheets below it are fed overlapping each other.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to reduce the occurrence of sheet feeding failures due to insufficient sheet handling in a sheet feeding device that feeds sheets by blowing air onto the sheets. [Means for solving the problem]

[0008] One aspect of the present invention is a sheet feeding device including a sheet support section that supports a sheet, a feed roller that contacts the sheet supported by the sheet support section and feeds the sheet, an air blower that blows air toward the side edges of the sheet supported by the sheet support section, a detection means that is provided downstream of the feed roller in the sheet feeding direction and detects abnormal sheet feeding, a counting means that counts the number of sheets fed by the feed roller, a setting means that sets the number of sheets fed by the feed roller, and after the air blower has blown air toward the side edges of the sheets, and a control unit that controls an air feeding operation in which the feed roller feeds the number of sheets set in the setting means while the air blowing by the air blowing unit is stopped, and after the feed roller has fed the number of sheets to be fed, the air blowing unit blows air toward the side edges of the sheets, wherein when the detection unit detects an abnormality in sheet feeding, the control unit subtracts the number of sheets to be fed set by the setting unit based on the count value by the counting unit, and performs the air feeding operation with the subtracted number of sheets to be fed. [Effects of the Invention]

[0009] The present invention can provide a sheet feeding device that can eliminate insufficient sheet handling caused by air blowing and reduce the occurrence of sheet feeding failures. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a control block diagram of a sheet feeding device according to an embodiment of the present invention. [Figure 3] FIG. 2 is a schematic diagram showing the configuration of a manual feeding unit according to the embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram showing a state in which an air blowing operation is performed in the manual feeding portion according to the embodiment of the present invention. [Figure 5] FIG. 4 is a setting screen diagram of sheet information according to the embodiment of the present invention. [Figure 6]10 is a flowchart showing a sheet type setting procedure according to an embodiment of the present invention. [Figure 7] 10 is a flowchart showing sheet feeding control according to an embodiment of the present invention. [Figure 8] 4 is a flowchart showing image formation control according to an embodiment of the present invention. [Figure 9] 6 is a flowchart showing control for setting a predetermined number of sheets to be air-blowed according to an embodiment of the present invention. [Figure 10] 10 is a flowchart showing initialization control of an air blowing feed number counter, a predetermined air blowing number, and a jam occurrence cause storage area stored in a RAM according to an embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing a list of jam codes. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Embodiment> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a cross-sectional view of an image forming system according to this embodiment. As shown in Fig. 1, an image forming system 600 includes an image forming apparatus 201 and a feed deck 500 connected to the image forming apparatus 201. The feed deck 500 is connected to the right side of the image forming apparatus 201 in Fig. 1, and is configured to be able to feed a sheet S to the image forming apparatus.

[0012] <Image forming device> In Fig. 1, 201 is an image forming apparatus, 201A is an image forming apparatus main body, and 201B is an image forming unit that forms an image on a sheet. 202 is an image reading device installed horizontally above the image forming apparatus main body 201A, and the image forming apparatus main body 201A is equipped with the image forming unit 201B. In addition, an ejection space V for ejecting sheets is formed between the image reading device 202 and the image forming apparatus main body 201A. Note that an operation unit 730 composed of a touch panel or the like that can display a screen is disposed above the image forming apparatus main body 201A.

[0013] Image forming unit 201B, which is an image forming means, is provided in the center in the vertical direction of image forming apparatus main body 201A, and mainly includes a laser scanner 210, a process cartridge 211, and a toner cartridge 215. Furthermore, process cartridge 211 is a four-drum full-color type, and includes four color process cartridges (211Y, 211M, 211C, and 211K) of yellow (Y), magenta (M), cyan (C), and black (K). Each process cartridge 211 includes a photosensitive drum 212, a charger 213, which is a charging means, and a developer 214, which is a developing means.

[0014] An intermediate transfer unit 201C is disposed above the process cartridge 211. The intermediate transfer unit 201C includes an intermediate transfer belt 216 wound around a drive roller 216a and a tension roller 216b. A primary transfer roller 219 is disposed inside the intermediate transfer belt 216 and abuts against the intermediate transfer belt 216 at a position facing the photosensitive drum 212. The intermediate transfer belt 216 is rotated in the direction indicated by the arrow by the drive roller 216a, which is driven by a drive unit (not shown). The negative color toner images on the photosensitive drums are superimposed and transferred to the intermediate transfer belt 216 in the order of YMCK by the primary transfer roller 219. A secondary transfer roller 217 is disposed opposite the drive roller 216a of the intermediate transfer unit 201C and transfers the color image formed on the intermediate transfer belt to the sheet S. The intermediate transfer belt 216 and the secondary transfer roller 217 constitute a secondary transfer section 201D. The toner cartridge 215 is disposed above the intermediate transfer unit 201C.

[0015] Furthermore, above the secondary transfer roller 217, a fixing unit 201E having a pressure roller 220a and a heating roller 220b is disposed.

[0016] In addition, a first discharge roller pair 225a, a second discharge roller pair 225b, and a double-sided reversing unit 201F are arranged in the upper left of the fixing unit 201E. The double-sided reversing unit 201F is provided with a reversing roller pair 222 that can rotate forward and backward, and a re-conveying path R that conveys the sheet with an image formed on one side to the image forming unit 201B again.

[0017] A sheet feeding unit 230 is provided at the bottom of the image forming apparatus main body 201A, which feeds set sheets S to the image forming section 201B. The sheet feeding unit 230 includes a feeding cassette 1 that stores sheets, and a sheet feeding section 506 that feeds the sheets S stored in the feeding cassette 1. The sheet feeding section 506 includes a pickup roller 2, and a feed roller 3 and a retard roller as a separation means that separates sheets S that have been fed from the pickup roller 2 and have been fed in a multi-fed state.

[0018] Further, a manual feed section 235 that feeds set sheets S to the image forming section 201B is provided on the right side surface of the image forming apparatus main body 201A in FIG. 1. The manual feed section 235 includes a manual tray 6 that supports the sheets S, and similarly to the sheet feeding unit 230, includes a sheet feeding means and a separation means. Further, a feed deck 500 that feeds set sheets S to the image forming section 201B is provided below the manual feed section 235 on the right side surface of the image forming apparatus main body 201A in FIG. 1. The manual feed section 235 will be described in detail later.

[0019] Next, the image forming operation of the image forming apparatus 201 will be described. First, image information of an original is read by the image reading device 202. After image processing, this image information is 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 photosensitive drum 212, the surface of which has been uniformly charged to a predetermined polarity and potential by the charger 213, is sequentially exposed to laser light. As a result, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photosensitive drum of each process cartridge 211, respectively.

[0020] Thereafter, this electrostatic latent image is developed and visualized with toner of each color, and the toner images of each color on each photosensitive drum are transferred in order onto the intermediate transfer belt 216 in a superimposed manner by a primary transfer bias applied to the primary transfer roller 219. As a result, a toner image is formed on the intermediate transfer belt 216.

[0021] Meanwhile, the sheet S fed by the feed rollers 3 of the sheet feeding unit 230 is conveyed to a pair of registration rollers (hereinafter referred to as the registration roller pair) 240, which consists of a drive roller and a driven roller. At this time, the driving of the registration roller pair 240 is stopped, and the leading edge of the sheet S abuts against the registration roller pair 240. As a result, the leading edge of the sheet S is made to follow the nip of the registration roller pair 240. Thereafter, as the sheet S continues to be conveyed by the feed rollers 3, a flexure (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 sheet S with the skew corrected is conveyed to the secondary transfer portion 201D by the registration roller pair 240. Subsequently, in the secondary transfer portion 201D, the toner images are transferred all at once onto the sheet S by a secondary transfer bias applied to the secondary transfer roller 217. The sheet S onto which the toner image has been transferred is then conveyed to the fixing section 201E, where the toner of each color is melted and mixed under heat and pressure, and fixed onto the sheet S as a color image.

[0022] Thereafter, the sheet S on which the image has been fixed is discharged into the discharge space V by a first discharge roller pair 225a and a second discharge roller pair 225b provided downstream of the fixing unit 201E, and is stacked on a stacking unit 223 formed on the bottom surface of the discharge space V. When images are formed on both sides of the sheet S, after the images are fixed, the sheet S is transported to a re-conveyance path R by a reversing roller pair 222, and is transported again to the image forming unit 201B.

[0023] As described above, the image forming process for forming an image and the sheet transport process for transporting a sheet to form an image on it are linked together to form an image on the sheet.

[0024] <Manual feed section> Next, the manual feeding unit 235 as a sheet feeding device will be described in detail with reference to FIGS.

[0025] First, the control configuration for sheet feeding in the manual feed unit will be described with reference to the control block diagram in FIG. 2. The control unit 100 according to this embodiment is provided in, for example, the image forming apparatus 201, and includes a CPU 101, a ROM 102, and a RAM 103. The control unit 100 is a control means that controls the image forming apparatus 201, the feed deck 500, and the manual feed unit 235 in an integrated manner. The control unit 100 is connected to a host device 900 and an operation unit 730, and performs signal processing and sequence control for various process devices while exchanging information with them. The host device 900 is an external device such as a personal computer, image scanner, or facsimile machine.

[0026] Control unit 100 is also connected to fan control unit 402, feed motor 520, which drives pickup roller 501, torque measurement unit 520a, which measures the motor torque of feed motor 520, and feed sensor 505. Torque measurement unit 520a measures the motor torque of feed motor 520, but may be, for example, a current sensor that detects the value of current flowing through feed motor 520 or a torque sensor that detects the torque generated in pickup roller 501. In other words, torque measurement unit 520a may have any specific configuration as long as it can measure the motor torque of feed motor 520. Fan control unit 402 controls the rotation of fans 511a and 511b while simultaneously detecting a malfunction. A malfunction can be determined by counting the number of fan rotations and determining whether the intended number of rotations has been reached.

[0027] 3 is a schematic diagram showing the configuration of the manual feed unit 235 according to this embodiment. The manual feed unit 235 includes a manual tray 6 as a sheet storage unit, and a sheet feed unit 506 that feeds sheets and separates the sheet stack. The sheet feed unit 506 includes a pickup roller 501 as a feed roller that contacts the top sheet of the sheet stack and feeds the top sheet. The sheet feed unit 506 also includes a feed roller 502 and a retard roller 503 as a separation unit that separates the sheet S fed from the pickup roller 501. In the manual feed unit 235, a pull-out roller 504 is disposed downstream of the feed roller 502 in the sheet feeding direction to pull out the sheet S from the feed roller 502 and feed it to the image forming apparatus 201. Furthermore, a feed sensor 505 serving as a sheet detection means is disposed between the feed roller 502 and the pull-out roller 504 in the sheet feeding direction, that is, downstream in the feeding direction of the sheet feeding unit 506. 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] 3, the manual feed tray 6 is provided with a manual feed tray base 515 and a lifter plate 514 as a sheet support portion that supports and stacks a sheet bundle consisting of a plurality of sheets S. The lifter plate 514 is also provided with a sheet presence / absence detection sensor 401 that can determine whether a sheet bundle has been stacked on the lifter plate 514. The height position of the lifter plate 514 is controlled by a lifting mechanism (not shown) in accordance with the amount of stacked sheets S. The manual feed tray 6 is also provided with side edge restriction plates 511 and 512, and the side edge restriction plates 511 and 512 restrict the position of the widthwise ends (side edges of the sheets) of the sheets S set on the lifter plate 514.

[0029] Furthermore, side edge regulating plates 511 and 512 are provided with air blowing sections 511A and 512A, respectively, as air blowing sections. Air blowing section 511A of side edge regulating plate 511 has fan 511b driven by fan motor 511M (see FIG. 2) and blowing nozzle 511a that guides the air blown from fan 511b and blows it from the side of the sheet stack. Similarly, air blowing section 512A of side edge regulating plate 512 has fan 512b driven by fan motor 512M (see FIG. 2) and blowing nozzle 512a that guides the air blown from fan 512b and blows it from the side of the sheet stack. In addition, the side end regulating plates 511, 512 are provided with floating suppression plates 511c, 512c near the blowing nozzles 511a, 512a to prevent the sheet S, to which air is blown, from floating up and climbing over the side end regulating plates 511, 512.

[0030] Next, the state of the sheets S when air is blown from the side edges of the sheet stack by the air blowing units 511A and 512A will be described with reference to Fig. 4. Fig. 4 is a schematic diagram showing a state in which an air blowing operation by a fan (hereinafter referred to as "air blowing operation") is performed in the manual feed unit 235 according to this embodiment.

[0031] As shown in FIG. 4, air is blown toward the sides of the sheet stack from fans 511b and 512b of air blowing units 511A and 512A as indicated by arrows A1 and A2. As a result, several to several tens of sheets S at the top of the stack of sheets are raised. The uppermost raised sheet contacts lift-up suppression plates 511c and 512c, thereby restricting the lift-up of sheets S. This air-blowing action reduces the adhesion between sheets. Even sheets S with smooth surfaces, such as coated paper, can be separated and fed one by one by feed roller 502 and retard roller 503.

[0032] <Sheet type settings> Setting of sheet information such as the size and type of the sheet set in the manual feed tray 6 will be described with reference to FIGS.

[0033] Various settings for the sheet are set using an operation unit 730. Fig. 5(a) is a diagram showing the operation unit 730 in the image forming apparatus of Fig. 1. The operation unit 730 is provided with a start key 702 for starting the image forming operation, a stop key 703 for interrupting the image forming operation, numeric keys 704 to 712 and 714 for setting numbers etc., an ID key 713, a clear key 715, a reset key 716, etc. Also provided is a display unit 720 with a touch panel formed on the top, and soft keys can be created on the screen.

[0034] When the user presses the "Paper Selection" button on the display unit 720 shown in FIG. 5(a), the CPU 101 transitions to a paper feed tray selection screen shown in FIG. 5(b) (S201). Then, the user selects which paper feed tray to feed sheets from (S202). Here, the user selects the manual feed tray and presses the "Next" button (S203). When the button is pressed, the CPU 101 transitions to a sheet size setting screen shown in FIG. 5(c). Here, the user selects the A3 size set in the manual feed tray (S204) and presses the "Next" button (S205). The CPU 101 transitions to a sheet type setting screen shown in FIG. 5(d). Here, the user selects the type of sheet set in the sheet storage unit (S206) and presses the "OK" button (S207). When the button is pressed, the set sheet information is saved in the RAM 103 (S208), the screen transitions to the initial screen of FIG. 5(a), and the sheet registration operation is completed (S209).

[0035] After setting the sheet information, pressing the start key 702 on the operation display device 700 starts the job and a sheet is fed from the selected sheet storage unit. It is not necessary to set the sheet information every time before starting a job. For example, if you set plain A3 paper in the manual feed tray and executed a job, and then want to execute a job that feeds plain A3 paper from the manual feed tray again, all you have to do is press the start key 702.

[0036] <Sheet feeding control and image formation control> Next, sheet feeding control and image forming control according to this embodiment will be described with reference to FIGS.

[0037] FIG. 7 is a flowchart showing sheet feeding control according to this embodiment. When printing begins in the image forming apparatus 201, the control unit 100 executes sheet feeding control initiation (S1). First, a job feeding number counter, which is used to compare whether the number of sheets S fed has reached the number required to be fed to the image forming unit based on the print job command, is cleared to 0 (S2). Next, a predetermined air blowing number is set to set the number of sheets to be fed for performing an air blowing operation for each predetermined number of sheets fed (S3). The predetermined air blowing number is compared with an air blowing feeding number counter, which is incremented as a count value each time a sheet S is fed. The predetermined air blowing number, the air blowing feeding number counter, and the job feeding number counter are stored in RAM 103 within the control unit 100. The control for setting the predetermined air blowing number will be described later with reference to FIG. 9.

[0038] Next, if the current air blowing feeding number counter has reached the predetermined number of sheets set in S3 (Yes in S4), the air blowing feeding number counter is cleared to 0 (S5). Subsequently, the air blowing operation to the sheet stack is started (S6), and a predetermined time (10 seconds in this embodiment) is awaited (No in S7). If the predetermined time has elapsed since the air blowing to the sheet stack (Yes in S7), the air blowing operation to the sheet stack is stopped (S8). Then, the pickup roller 501 of the feeding unit 506 separates the topmost sheet S from the sheet stack and feeds it (S9). At this time, the sheets S are continuously fed in a predetermined number of sheets with the air blowing stopped. In this embodiment, the air feeding operation is an operation in which the air blowing unit blows air to separate the sheets, and then the feeding roller feeds multiple sheets with the air blowing by the feeding unit stopped.

[0039] As a result of feeding the sheet S in S9, the control unit 100 checks whether a feeding-related jam has occurred as a feeding abnormality (S10). In this embodiment, the control unit 100 detects a feeding-related jam using the feeding sensor 505 and the double feed detection sensor 507. As the double feed detection sensor 507, a method of detecting the space between overlapping sheets S using an ultrasonic sensor, or a method of detecting the amount of light transmitted through the sheets S is generally known.

[0040] If it is determined that a feed-related jam has occurred (Yes in S10), the occurrence of the feed-related jam is stored as a jam code in the jam cause storage area of ​​RAM 103 (S11). As shown in FIG. 11, the jam code is composed of "jam occurrence area + presence / absence of air blowing + jam detection type + sensor number." For example, the jam code detected using feed sensor 505 is feed sensor delay jam FF105. Furthermore, the jam code detected using double feed detection sensor 507 is double feed jam FF307 when a sheet is fed from manual feed unit 235, which blows air. When a sheet is fed from sheet feeding unit 230, which does not blow air, it is double feed jam FN307. Because sheet feeding unit 230 does not have air blowing units 511A and 511B like manual feed unit 235, it feeds sheets without blowing air. As explained in the description of FIG. 1, the sheet feeding unit 230 feeds sheets using the pickup roller 2, and separates the sheets using the feed roller 3 and the retard roller. A jam of a sheet fed from the sheet feeding unit 230 is detected using the cassette 1 feed sensor 10. The jam code detected using the cassette 1 feed sensor 10 is FN110. (Jams of sheets fed from feed cassettes 2 to 4 below feed cassette 1 are also detected using their respective feed sensors.) The control unit 100 then waits until it receives a request to stop the print job due to a jam (No in S12), and if it receives a request to stop the print job due to a jam (Yes in S12), it ends sheet feeding control for the job (S16).

[0041] If no feeding-related jam has occurred (No in S10), the air blow feeding sheet number counter is counted up (S13), and the job feeding sheet number counter is counted up (S14). If the job feeding sheet number counter has reached the number of sheets required to be fed to the image forming unit 201B based on the command of the print job (Yes in S15), the sheet feeding control for the job is terminated (S16). If the job feeding sheet number counter has not reached the number of sheets required to be fed to the image forming unit based on the command of the print job (No in S15), the process returns to S4. Thereafter, the process is repeated from S4 until the job feeding sheet number counter reaches the number of sheets required to be fed to the image forming unit.

[0042] In this embodiment, the control unit 100 checks for the occurrence of a feeding-related jam every time a sheet is fed through the above-described sheet feeding control. Based on this information, if a jam occurs, the location of the jam is stored and the device is stopped, whereas if no jam occurs, the control unit counts up the number of fed sheets counter.

[0043] Next, a flowchart illustrating image formation control according to this embodiment will be described with reference to FIG. 8. When printing begins in the image forming apparatus 201, the control unit 100 starts image formation control (S21). First, a discharged sheet counter, which is used to compare whether the number of sheets S on which images are formed reaches the number of sheets required for image formation based on the print job command, is cleared to 0 (S22). Next, the control unit waits until the sheet S is fed to the image forming unit 201B by the sheet feeding control described with reference to FIG. 7 (No in S23). If a feeding-related jam occurs while waiting for the completion of feeding of the sheet S and a request to stop the print job due to the jam is received (Yes in S29), the control unit ends image formation control (S32). If a request to stop the print job due to the jam is not received (No in S29), the control unit returns to S23. If the feeding of the sheet S is completed (Yes in S23), image formation by the image forming unit 201B begins (S24). At the start of image formation, the sheet S passes through the image forming unit 201B and the fixing unit 201E, and is discharged to the discharge space V by the first discharge roller pair 225a or the second discharge roller pair 225b. The control unit 100 monitors for occurrence of a jam during image formation (S25) until the sheet S is discharged (No in S26). The control unit 100 detects a jam during image formation using the fixing exit sensor 301, the first discharge sensor 302, and the second discharge sensor 303.

[0044] If a jam occurs during image formation (Yes in S25), the cause of the jam during image formation is stored in the jam cause storage area of ​​RAM 103 as a jam code corresponding to the type of jam (S30). As shown in FIG. 11, the jam codes detected using the fixing exit sensor 301 are fixing exit sensor delay jam IN101 and fixing exit sensor retention jam IN201. The jam codes detected using the first discharge sensor 302 are first discharge sensor delay jam IN102 and first discharge sensor retention jam IN202. The jam codes detected using the second discharge sensor 303 are second discharge sensor delay jam IN103 and second discharge sensor retention jam IN203. The process then waits until a request to stop the print job due to a jam is received (No in S31). If a request to stop the print job due to a jam is received (Yes in S31), the image formation control is terminated (S32).

[0045] If no jam occurs during image formation (No in S25), the process waits for completion of sheet discharge in which sheet S is discharged into discharge space V (No in S26). If completion of sheet discharge in which sheet S is discharged into discharge space V is achieved (Yes in S26), the discharged sheet number counter is counted up (S27). If the discharged sheet number counter reaches the number of sheets required for image formation by image forming unit 201B based on the command of the print job (Yes in S28), the image formation control for the job ends (S32). If the discharged sheet number counter does not reach the number of sheets required for image formation by image forming unit 201B based on the command of the print job (No in S28), the process returns to waiting for completion of feeding of sheet S in S23, and image formation control is repeated until the discharged sheet number counter reaches the required number.

[0046] With the image formation control described above, in this embodiment, the control unit 100 checks whether a jam has occurred during image formation every time a sheet is discharged. Based on this information, if a jam has occurred, the location of the jam is stored and the device is stopped, whereas if no jam has occurred, the control unit counts up the number of discharged sheets.

[0047] <Setting the number of sheets to be blown with air and controlling sheet feeding> Next, the setting of the predetermined number of sheets to be subjected to air blowing according to this embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a flowchart showing the control of determining the predetermined number of sheets to be subjected to air blowing (S3) in the sheet feeding control described with reference to Fig. 7.

[0048] When the control unit 100 starts the process of determining the predetermined number of sheets for air blowing (S41), it first checks whether a jam code indicating the cause of the jam is stored in the jam cause storage area of ​​RAM 103 (S42). If the value in the jam cause storage area of ​​RAM 103 is 0 and no jam code is stored (No in S42), the control for determining the predetermined number of sheets for air blowing ends (S48). In this case, the predetermined number of sheets for air blowing is held in RAM 103 as its current value.

[0049] If a jam code other than 0 indicating a jam has occurred is stored in the jam cause storage area of ​​RAM 103 (Yes in S42), it is checked whether the cause of the jam is a feed-related jam based on the jam code (S43). Whether the jam is a feed-related jam can be determined from the top two characters of the jam code configuration shown in Figure 11, which indicate the jam occurrence area and whether air is being blown. The feed sensor delay jam FF105 and the double feed jam FF307, which have the top two characters FF, are determined to be feed-related jams.

[0050] If it is determined to be a feeding-related jam (Yes in S43), it is possible that the adhesion between the sheets was unexpectedly strong, and the lifting of the predetermined number of sheets stacked above the sheet stack was small, resulting in insufficient separation. Therefore, it is presumed that the feeding-related jam occurred before the air blowing feed number counter reached the predetermined number. To resolve this insufficient separation, the predetermined number of sheets for air blowing is set to be less than the number of sheets that would cause a feeding-related jam, as follows:

[0051] First, it is confirmed that the current air blowing feeding number counter stored in RAM 103 is greater than 1 (Yes in S44). The value of the predetermined air blowing number is updated to the value obtained by subtracting 1 from the air blowing feeding number counter when the feeding-related jam occurred, and this value is stored in RAM 103 (S45). If the current air blowing feeding number counter is 1 or less (No in S44), the predetermined air blowing number is set to the minimum value of 1 (S46). Thereafter, the jam occurrence cause storage area in RAM 103 is cleared to 0 (S47), and the control for determining the predetermined air blowing number is terminated (S48).

[0052] If the cause of the jam is not a feeding-related jam (No in S43), it can be determined that there is no problem in handling the sheet stack by air blowing. Therefore, the predetermined number of sheets to be blown by air blowing is not updated, and only the jam occurrence cause storage area in RAM 103 is cleared to 0 (S47), and the control for determining the predetermined number of sheets to be blown by air blowing is terminated (S48).

[0053] As described above, the control unit 100 counts down the setting of the predetermined number of sheets to be air-blowed depending on whether a feeding-related jam (based on the detection result of the double feed detection sensor or delay detection sensor) has occurred. As a result, if the countdown has occurred, the interval between feeding numbers for air-clearing operation is shortened, so that the loaded sheets can be better separated, and it becomes possible to eliminate the cause of jams due to insufficient separation by air-blowing.

[0054] Next, using Figure 10, we will explain a flowchart showing the initialization control of the air blowing feed number counter, the specified number of air blowing sheets, and the jam occurrence cause memory area stored in RAM 103 described in the control flow shown in Figures 7, 8, and 9.

[0055] The initialization control of FIG. 10 is performed when the adhesive force of the sheet stack may have changed. This occurs when the power switch of the image forming apparatus 201 is switched from OFF to ON, or when a sheet stack is placed on the manual feed tray 6 after no sheet stack was present. The initialization control is initiated by the control unit 100 (S61). In this embodiment, the predetermined number of sheets to be air-blowing is initialized to a predetermined value of 10 sheets (S62), and the air-blowing feeding number counter is also initialized to 10 sheets (S63). The jam occurrence cause storage area is cleared to 0 (S65) and stored in RAM 103, and the initialization control ends (S65). As a result, as shown in the sheet feeding control flow of FIG. 7, in a print job after the power is turned on or a sheet stack is placed on the manual feed tray 6, it is determined that the air-blowing feeding number counter has reached the predetermined number of sheets to be air-blowing (Yes in S4). That is, the air blowing operation is first initiated (S5).

[0056] As described above, according to the sheet feeding control and image forming control of this embodiment, when a feeding-related jam occurs that may be due to insufficient air blowing, the condition for the predetermined number of sheets to be blown with air is switched to the number of sheets just before a feeding failure occurs. This reduces the interval between the number of sheets fed for which the air blowing operation is performed, thereby improving the handling of the stacked sheets. In other words, it is possible to eliminate the cause of jams due to insufficient air blowing handling. As a result, it is possible to provide a sheet feeding device and an image forming system that can eliminate insufficient air blowing handling and reduce the occurrence of feeding-related jams. [Explanation of symbols]

[0057] 100 control section 201B Image forming section 235 Manual feeding unit (sheet feeding device) 514 Lifter plate (seat support part) 501 Pickup roller (feed roller) 511A, 512A Air blowing section (blower section) 505 Feeding sensor (sheet detection means) 506 Sheet feeding section 507 Double feed detection sensor (double feed detection means) S seat

Claims

1. a seat support portion that supports the seat; a feeding roller that contacts the sheet supported by the sheet supporting portion and feeds the sheet; a blower that blows air toward a side end of the seat supported by the seat support; a detection means provided downstream of the feeding roller in the sheet feeding direction, for detecting abnormal sheet feeding; a counting means for counting the number of sheets fed by the feeding roller; a setting means for setting the number of sheets to be fed by the feeding roller; a control unit that controls an air feeding operation in which, after the air blowing unit has blown air toward the side edges of the sheets, the feed roller feeds the number of sheets set by the setting means while the air blowing unit is stopped, and, after the number of sheets to be fed has been fed by the feed roller, the air blowing unit blows air toward the side edges of the sheets, when the detection means detects a sheet feeding abnormality, the control unit subtracts the number of sheets to be fed set by the setting means based on the count value by the counting means, and performs the air feeding operation with the subtracted number of sheets to be fed. A sheet feeding device characterized by:

2. the detection unit is a double feed detection unit that detects double feed of the sheets fed from the sheet feeding unit, the control unit, when the multi-feed detection unit detects a multi-feed of sheets, executes the air feeding operation with the subtracted number of sheets to be fed.

2. The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device.

3. the detection means is a sheet detection means that detects an edge of the sheet fed from the sheet feeding unit, the control unit executes the air feeding operation with the subtracted number of sheets to be fed when the sheet detection unit detects a delay or a stagnation of the sheets.

2. The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device.

4. The sheet feeding device according to any one of claims 1 to 3, an image forming unit that forms an image on the sheet fed by the sheet feeding device.

5. a sheet presence / absence detection means for detecting the presence or absence of a sheet placed on the sheet support portion; a switch means for supplying power to the image forming apparatus; a resetting means for resetting the subtracted number of sheets fed and the count value by the counting means to predetermined values, When the switch means switches from an OFF state to an ON state, or when the sheet presence / absence detection means detects a sheet, the control unit resets the subtracted number of fed sheets and the count value to the predetermined values ​​by the reset means.

5. The image forming apparatus according to claim 4.

Images