Sheet feeding device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- CANON KK
- Filing Date
- 2023-07-13
- Publication Date
- 2026-07-23
AI Technical Summary
Existing sheet feeding devices face issues with sheet adhesion in bundles, leading to problems like multiple sheets being delivered simultaneously, especially with smooth sheets like coat paper, causing defects such as heavy feeding.
The device employs a sheet support unit with air handling parts that spray air onto the sheet bundle to reduce adhesion, followed by controlled sheet feeding operations, including air spraying and sheet transmission, and adjusts the air spraying based on the presence or absence of sheets to prevent sheet loss.
This approach reduces sheet defects like heavy feeding and improves printing accuracy by minimizing sheet adhesion and diagonal lines, ensuring smooth feeding and high-quality output.
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a sheet feeding device that feeds a sheet. [Background technology]
[0002] In recent years, there has been an increasing demand for forming images on various types of sheets, and sheets with smooth surfaces, such as coated paper, are sometimes used as recording materials. When a stack of sheets with such smooth surfaces is set in a sheet feeding device that feeds the sheets, the sheets may adhere closely to each other, making it difficult to feed the sheets. According to Patent Document 1, a sheet feeding device is proposed that blows air onto the sheet stack to lift the sheets and handle the sheets. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-23747 Summary of the Invention [Problem to be solved by the invention]
[0004] A general control in which air is blown onto a stack of sheets to separate them and feed the sheets as in the above-mentioned Patent Document 1 will be described with reference to FIG. 9. As shown in FIG. 9, when the control for feeding sheets is started in response to a command such as the start of a print job (S101), first, air blowing toward the stack of sheets is started (S102). Air blowing is continued until a predetermined time (for example, 10 seconds) has elapsed since the start of air blowing (No in S103). Then, when the predetermined time has elapsed since the start of air blowing (Yes in S103), a feeding operation is performed to feed the sheets to the image forming unit by a pickup roller or the like (S104). Then, the feeding operation is repeated until the required number of sheets to be fed to the image forming unit based on the command of the print job is reached (No in S105), and when the required number of sheets is reached (Yes in S105), air blowing is stopped (S106) and this control is terminated (S107).
[0005] However, in the above-mentioned control, for example, when the sheets run out during a job and the job is interrupted, and a new sheet stack is set in the sheet feeding device and the job is resumed, the sheets are fed without blowing air onto the sheet stack, which may cause a transport failure such as a double feed in which multiple sheets are fed at the same time.
[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a sheet feeding device capable of reducing sheet transport failures. [Means for solving the problem]
[0007] The present invention is a sheet feeding device comprising a sheet supporting section that supports a sheet stack, a sheet feeding section that abuts against the top sheet of the sheet stack supported by the sheet supporting section and performs a feeding operation to feed the top sheet, an air handling section that performs a blowing operation to blow air against the sides of the sheet stack supported by the sheet supporting section to handle the sheets, and a control section that executes sheet feeding control in which the air handling section performs the blowing operation, stops the blowing operation, and then performs the feeding operation by the sheet feeding section while the blowing operation is stopped, wherein the control section is characterized in that, in the sheet feeding control, after performing the blowing operation, when the sheet feeding section performs the feeding operation on a predetermined number of sheets after performing the blowing operation, it performs the blowing operation again, and when there are no more sheets supported by the sheet supporting section, it performs the blowing operation on the next sheet stack supported by the sheet supporting section before performing the feeding operation. Effect of the Invention
[0008] According to the present invention, it is possible to reduce sheet transport failures. [Brief description of the drawings]
[0009] [Figure 1] 1 is an overall schematic diagram showing an image forming system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a control system of the image forming system. [Diagram 3] FIG. 4 is a schematic diagram showing a configuration of a manual feeding section. [Figure 4] FIG. 11 is a schematic diagram showing a state in which an air blowing operation is performed in the manual feed section. [Diagram 5] 11 is a flowchart showing sheet feeding control. [Figure 6] 11 is a flowchart showing a history change control without a sheet. [Figure 7] FIG. [Figure 8] 5A and 5B are diagrams for explaining the generation of a rotational force due to the positional relationship between a pickup roller and a feed roller. [Figure 9]11 is a flowchart showing a general sheet feeding control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, an image forming system 600 including a feed deck 500 and an image forming apparatus 201 connected thereto will be described with reference to Fig. 1. Fig. 1 is a diagram showing a schematic configuration of the image forming system according to this embodiment.
[0011] [Outline of image forming system] 1, the 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 201.
[0012] [General configuration of image forming device] 1, the image forming apparatus 201 has an image forming apparatus main body 201A including an image forming unit 201B that forms an image on a sheet, and an image reading device 202 disposed above the image forming apparatus main body 201A. Between the image reading device 202 and the image forming apparatus main body 201A, a discharge space V for discharging sheets is formed. An operation unit 730 constituted by a touch panel or the like capable of displaying a screen is disposed above the image forming apparatus main body 201A.
[0013] The image forming section 201B employs a four-drum full-color system. The image forming section 201B includes a laser scanner 210 and four process cartridges 211Y, 211M, 211C, and 211K that form toner images of four colors, yellow (Y), magenta (M), cyan (C), and black (K). Here, each process cartridge 211 includes a photosensitive drum 212, a charger 213, and a developing device 214. The image forming section 201B also includes an intermediate transfer unit 201C disposed above the process cartridge 211, and a fixing section 201E. Note that a toner cartridge 215 for supplying toner to the developing device 214 is disposed above the image forming section 201B.
[0014] 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 provided on the inner side of the intermediate transfer belt 216, and contacts the intermediate transfer belt 216 at a position facing the photosensitive drum 212. The intermediate transfer belt 216 is rotated in the direction of the arrow in FIG. 1 by a drive roller 216a driven by a drive unit (not shown).
[0015] Then, the toner images of each color having a negative polarity on the photosensitive drum are sequentially transferred in a multi-layer manner to the intermediate transfer belt 216 by the primary transfer roller 219. A secondary transfer roller 217 that transfers the color image formed on the intermediate transfer belt to the sheet P is provided at a position facing the driving roller 216a of the intermediate transfer unit 201C. The intermediate transfer belt 216 and the secondary transfer roller 217 form a secondary transfer section 201D. Furthermore, a fixing section 201E having a pressure roller 220a and a heating roller 220b is provided above the secondary transfer roller 217. In addition, a first discharge roller pair 225a, a second discharge roller pair 225b, and a double-sided reversing section 201F are provided at the upper left of the fixing section 201E. The double-sided reversing section 201F is provided with a reversible reversing roller pair 222 and a re-conveying passage R that conveys the sheet with an image formed on the first side to the image forming section 201B again.
[0016] A plurality of (four in this embodiment) sheet feeding units 230 are provided at the bottom of the image forming apparatus main body 201A, which feed the set sheets S to the image forming section 201B. Each sheet feeding unit 230 includes a feeding cassette 1 for storing sheets, and a sheet feeding section 5 for feeding the sheets S stored in the feeding cassette 1. The sheet feeding section 5 includes a pickup roller 2, and a feed roller 3 and a retard roller as a separation section for separating the sheets S fed from the pickup roller 2 and fed in a duplicated manner.
[0017] Further, on the right side surface of the image forming apparatus main body 201A in FIG. 1, there is provided a manual feed section 235 that feeds the set sheet S to the image forming section 201B. The manual feed section 235 includes a manual feed tray 6 as a sheet support section that supports the sheet S. The manual feed tray 6 is supported by the image forming apparatus main body 201A as a housing so as to be openable and closable. A detailed configuration of the manual feed section 235 will be described later. Further, on the right side surface of the image forming apparatus main body 201A in FIG. 1, below the manual feed section 235, there is provided a feed deck 500 that feeds the set sheet S to the image forming section 201B.
[0018] 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, and the image information is image-processed, converted into an electric signal, and transmitted to the laser scanner 210 of the image forming section 201B. In the image forming section 201B, the surface of the photosensitive drum 212, the surface of which is 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.
[0019] Thereafter, the electrostatic latent images are developed and visualized with toner of each color, and the toner images of each color on each photoconductor 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.
[0020] On the other hand, the sheet S fed by the feed roller 3 of the sheet feeding unit 230 is conveyed to a pair of registration rollers (hereinafter referred to as the registration roller pair) 240 consisting 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 is abutted against the registration roller pair 240. As a result, the leading edge of the sheet S is made to follow the registration roller pair 240. Thereafter, as the sheet S continues to be conveyed by the feed roller 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 collectively 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 a fixing section 201E, where the toner of each color is melted and mixed by heat and pressure, and is fixed onto the sheet S as a color image.
[0021] Thereafter, the sheet S on which the image has been fixed is discharged to the discharge space V by the first discharge roller pair 225a or the second discharge roller pair 225b provided downstream of the fixing section 201E, and is stacked on the stacking section 223 formed on the bottom surface of the discharge space V. When an image is formed on both sides of the sheet S, after the image is fixed on the first side of the sheet S, the sheet S is transported to the re-conveyance path R by the reversing roller pair 222, and is transported again to the image forming section 201B. Then, an image is formed on the second side of the sheet S, which is opposite to the first side, and the sheet S is discharged to the stacking section 223.
[0022] [Manual feed section configuration] Next, the manual feed unit 235 as a sheet feeding device will be described in detail with reference to Fig. 1 and Fig. 3. Fig. 3 is a schematic diagram showing the configuration of the manual feed unit 235 according to the present embodiment. As shown in Fig. 1 and Fig. 3, the manual feed unit 235 includes a manual tray 6 and a sheet feed unit 506 that feeds a sheet and separates overlapped sheets.
[0023] Moreover, the sheet feeding unit 506 includes a pickup roller 501 as a feeding roller that comes into contact with the top sheet of a sheet stack supported by a sheet stacking plate 514 described later and feeds the top sheet. Furthermore, the sheet feeding unit 506 includes a feed roller 502 and a retard roller 503 as a separating unit that separates the sheet S fed from the pickup roller 501.
[0024] Further, in the manual feed section 235, downstream in the sheet feeding direction of the feed roller 502, there is disposed a pull-out roller 504 (see FIG. 1) which pulls out the sheet S from the feed roller 502 and feeds it to the image forming apparatus 201. In the sheet feeding direction, between the feed roller 502 and the pull-out roller 504, that is, downstream in the feeding direction of the sheet feeding section 506, there is disposed a feed sensor 505. 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.
[0025] 3, the manual feed tray 6 is provided with a sheet stacking plate 514 that stacks and supports a sheet bundle consisting of a plurality of sheets S, a support base 515 that supports the sheet stacking plate 514, and a sheet presence / absence sensor 401. The sheet presence / absence sensor 401 can detect the presence or absence of sheets (including a sheet bundle) on the sheet stacking plate 514. For example, the sheet presence / absence sensor 401 may be a flag sensor that detects the position of a flag that moves when pressed by a sheet stacked on the sheet stacking plate 514, or may be an optical sensor that detects light reflected by a sheet.
[0026] The manual feed tray 6 is also provided with side end regulating plates 511, 512 and a rear end regulating plate 513. The side end regulating plates 511, 512 as regulating parts regulate the positions of the widthwise ends (side ends of the sheets) of the sheets S set on the sheet stacking plate 514. The width direction W of the sheets S is a direction perpendicular to the sheet feeding direction FD of the sheets S (sheet stack). The rear end regulating plate 513 regulates the position of the upstream end (rear end of the sheets) in the feeding direction of the sheets S.
[0027] These side end regulating plates 511 and 512 are provided with air blowing sections 511A and 512A as air handling sections. The air blowing section 511A of the side end regulating plate 511 has a fan 511b driven by a fan motor 511M (see FIG. 2) and a blowing nozzle 511a that guides the air blown from the fan 511b and blows it from the side of the sheet stack. Similarly, the air blowing section 512A of the side end regulating plate 512 has a fan 512b driven by a fan motor 512M (see FIG. 2) and a blowing nozzle 512a that guides the air blown from the fan 512b and blows it from the side of the sheet stack. These blowing nozzles 511a and 512a as blowing ports have a function of a duct that guides air inside the side end regulating plates 511 and 512. The side end regulating plates 511, 512 are provided with floating suppression plates 511c, 512c in the vicinity of 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.
[0028] [Configuration of the control system of the image forming system] Next, the configuration of a control system in the image forming system 600 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the control system of the image forming system according to the present embodiment.
[0029] The control unit 100 according to the present embodiment is provided in, for example, an image forming apparatus 201. The control unit 100 includes a central processing unit (CPU) 101, a read only memory (ROM) 102, and a random access memory (RAM) 103. The ROM 102 stores various programs, and the CPU 101 reads and executes any program from the ROM 102. The RAM 103 is used as a working area for the CPU 101. The control unit 100 controls the image forming apparatus 201 and the feed deck 500. 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, an image scanner, or a facsimile. The operation unit 730 that can be operated by a user will be described later.
[0030] The control unit 100 is connected to the fan control unit 402 and the feed motor 520 as a motor that drives the pickup roller 501. The control unit 100 is also connected to a torque measurement unit 520a that measures the motor torque of the feed motor 520, the feed sensor 505, the sheet presence sensor 401, and the like. The fan control unit 402 is connected to the fan motors 511M and 512M, and performs rotation control of the fans 511b and 512b by the fan motors 511M and 512M, while simultaneously detecting failures of the fans 511b and 512b. Whether the fans 511b and 512b are broken can be determined, for example, by counting the number of rotations of the fans 511b and 512b and checking whether the counted number of rotations reaches an intended number of rotations.
[0031] Note that torque measuring unit 520a measures the motor torque of feed motor 520, but may be, for example, a current sensor that detects the value of a current flowing through feed motor 520, or a torque sensor that detects the torque generated in pickup roller 501. In other words, the specific configuration of torque measuring unit 520a may be anything that can directly or indirectly measure the motor torque of feed motor 520.
[0032] [Operation and problems when blowing air] Next, the state of the sheets S when air is blown from the side of the sheet stack by the air blowing units 511A and 512A, and problems that occur when the sheets S are fed while air is being blown thereon will be described with reference to Figs. 4 and 8. Fig. 4 is a schematic diagram showing a state in which an air blowing operation (hereinafter referred to as "air blowing operation") is performed by the feeding deck according to this embodiment. Fig. 8 is an explanatory diagram for explaining the generation of a turning force due to the positional relationship between the pickup roller 501 and the feed roller 502.
[0033] 4, fans 511b, 512b of air blowing units 511A, 512A blow air toward the side of the sheet stack as indicated by arrows A1, A2 during the air blowing operation. Then, several to several tens of sheets S at the top of the sheet stack are separated and floated, while the floating suppression plates 511c, 512c suppress the floating of the sheets S. This reduces the adhesion between the floating sheets S, and makes it possible to feed the sheets S by the pickup roller 501 even if the sheets S have a smooth surface, such as coated paper.
[0034] However, due to design considerations in relation to other components, the positions of the center C1 of the pickup roller 501 and the center C2 of the feed roller 502 may be misaligned by, for example, a distance X in the width direction perpendicular to the sheet feeding direction, as shown in FIG. 8. In this case, when a transport load occurs near the pickup roller 501 due to a difference in transport speed or the like while the topmost sheet S1 is being transported by the feed roller 502, a rotating force is generated in the sheet S1 in the counterclockwise direction. As a result, the sheet S1 is fed while rotating, causing the sheet S1 to skew. Here, even if a rotating force is generated on the sheet S1, the side edges of the sheet S1 usually come into contact with the side edge regulating plates 511 and 512, and the stiffness of the sheet S1 suppresses the skew.
[0035] However, because the sheet S1 is raised by the air blowing from the air blowing sections 511A and 512A, the sheet S1 is likely to bend as shown in Fig. 8. This reduces the effect of the side end regulating plates 511 and 512 in suppressing the skew of the sheet S1, and there is a problem that the amount of skew of the sheet S1 may increase. Therefore, in this embodiment, the sheet feeding control is performed as follows.
[0036] [Sheet feeding control] Next, the sheet feeding control of the manual feed unit 235 according to this embodiment will be described with reference to FIG. 5. FIG. 5 is a flowchart showing the sheet feeding control. When printing is started in the image forming apparatus 201, the control unit 100 starts sheet feeding control in order to feed a sheet (S301). Then, the control unit 100 first determines whether there is a sheet absence history (S302). The sheet absence history is information stored in the RAM 103, and will be described in detail in the sheet absence history change control described later with reference to FIG. 6. When the image forming apparatus 201 is started, the sheet absence history is set to "present".
[0037] If it is determined that there is a history of no sheets (Yes in S301), the control unit 100 clears the number of sheets that can be fed (S303) and proceeds to step S303. On the other hand, if it is determined that there is no history of no sheets (No in S301), the control unit 100 proceeds to step S304 without passing through step S303. Note that the "number of sheets that can be fed" is information stored in the RAM 103, and is cleared to 0 in step S303.
[0038] In step S304, the control unit 100 changes the no-sheet history to "none" (S304). Next, the control unit 100 determines whether the number of sheets that can be fed is greater than 0, i.e., whether it is 1 or more (S305). If the number of sheets that can be fed is greater than 0 (Yes in S305), the control unit 100 proceeds to step S310.
[0039] On the other hand, if the number of sheets that can be fed is 0 (No in S305), the control unit 100 drives the fan motors 511M and 512M to start an air blowing operation in which the air blowing units 511A and 512A blow air onto the sides of the sheet stack (S306). As a result, several to several tens of sheets S above the sheet stack are separated and floated, while the floating suppression plates 511c and 512c suppress the floating of the sheets S (see FIG. 4), reducing the adhesion between the sheets.
[0040] Since the fan motors 511M, 512M start rotating from a stopped state, a predetermined time, such as 10 seconds, is preset as the time required to reach a desired number of rotations (rotational speed) and the time required to stabilize the floating of the sheet S. Then, the air blowing operation is performed until the predetermined time has elapsed (No in S307), and when the predetermined time has elapsed (Yes in S307), the control unit 100 stops the air blowing operation (S308), that is, turns off the drive of the fan motors 511M, 512M.
[0041] As a result, the sheets S, which were in a floated state, attempt to return to the state of the sheet bundle before floating as the air between the sheets is released, but it takes a certain amount of time for the sheets S to return to the state of the sheet bundle before floating. Since the adhesive force between the sheets remains reduced until the sheet bundle returns to the state of the sheet bundle before floating, it is possible to feed even a sheet bundle with high adhesive force while suppressing double feeding. Since it is now possible to feed the sheet bundle while suppressing double feeding, the control unit 100 sets the number of sheets that can be fed to a predetermined number (step S309). The predetermined number is information that is stored in advance in the RAM 103, and is set to 10 sheets in this embodiment. Setting the number of sheets that can be fed to 10 sheets means that the manual feed unit 235 can feed 10 sheets before the air between the sheets is released and the sheet bundle returns to the state of the sheet bundle before floating.
[0042] Next, the control unit 100 starts the feeding operation of the sheet S (S310). The start of the feeding operation means that the pickup roller 501, in contact with the uppermost sheet S in the sheet stack, rotates by the feeding motor 520 to feed the sheet S. Thereafter, if the sheets S are fed in a double state in a separation unit consisting of a feed roller 502 and a retard roller 503, the sheets S are separated, and the passage of the sheets S is detected by a feeding sensor 505.
[0043] When one sheet S is fed, the control unit 100 decrements the number of sheets that can be fed by -1 (subtracts 1) (S311). In this embodiment, the feeding operation is repeated until the required number of sheets S, for example, 15 sheets, have been fed (No in S312), and when the required number of sheets have been fed (Yes in S312), the sheet feeding control by the manual feed unit 235 ends (S315). The required number is, for example, the number of prints specified in the job.
[0044] If the required number of sheets S has not been fed (No in S312), the control unit 100 judges whether the no-sheet history is “present” or not (S313). The no-sheet history change control for changing the no-sheet history from “absent” to “present” will be described later with reference to the flowchart in FIG. 6. If it is determined that the no-sheet history is “absent” (No in step S313), the control unit 100 returns to step S305. Then, the control unit 100 continues to feed the sheets S (S305 to S312) and performs the air blowing operation (S305 to S308) every time a predetermined number of sheets (for example, 10 sheets) are fed. In this way, when the required number of sheets S (for example, 15 sheets) are fed, the control unit 100 performs the sheet S feeding operation and the air blowing operation as long as the sheet stack stacked on the sheet stacking plate 514 of the manual feed tray 6 does not run out.
[0045] On the other hand, when it is determined that there is a history of no sheets (Yes in step S313), the control unit 100 displays a notification screen on the display unit 730a of the operation unit 730 as shown in FIG. 7, notifies the user of the absence of sheets (S314), and ends the sheet feeding control. The operation unit 730 as a notification unit capable of notifying the user has a display unit 730a configured with a liquid crystal panel or the like as shown in FIG. 7, and can notify the user that the sheets S have disappeared from the manual feed tray 6 and the job has been interrupted. The notification screen displayed on the display unit 730a displays a "Job Resume" button 731 and a "Cancel" button 732. The user can instruct the job to be resumed by loading a new sheet stack (sheets) on the sheet stacking plate 514 of the manual feed tray 6 and touching the "Job Resume" button 731. The user can also end the job by touching the "Cancel" button 732.
[0046] Next, the no-sheet history change control will be described with reference to the flowchart of Fig. 6. The no-sheet history change control is always executed by the CPU 101 of the control unit 100 while the image forming apparatus 201 is running. When the control unit 100 starts the no-sheet history change control (S351), it judges whether or not the sheets stacked on the sheet stacking plate 514 of the manual feed tray 6 have disappeared, that is, whether or not the no-sheet state has been detected, based on the detection result of the sheet presence / absence sensor 401 (S352). The no-sheet state is detected, for example, when the sheet runs out during a job or when the user removes the sheet stack that was stacked on the sheet stacking plate 514. When the control unit 100 does not detect the no-sheet state (No in S352), it waits until the no-sheet state is detected.
[0047] When the absence of sheets is detected (Yes in S352), the control unit 100 changes the information of the absence of sheets history in the RAM 103 to "Present" (S353). Next, the control unit 100 judges whether or not a new sheet stack (sheets) has been stacked on the sheet stacking plate 514 of the manual feed tray 6, that is, whether or not the presence of sheets has been detected, based on the detection result of the sheet presence sensor 401 (S354). When the control unit 100 does not detect the presence of sheets (No in S354), it waits until it detects the presence of sheets. When the presence of sheets is detected (Yes in S354), the control unit 100 returns to step S352.
[0048] Here, for example, consider a case where the required number of sheets for printing is 15, and sheet feeding control is started when a stack of 50 sheets is set on the sheet stacking plate 514. When a stack of 50 sheets is set on the sheet stacking plate 514 from a state where no sheets are stacked on the sheet stacking plate 514, the no-sheet history becomes "present" (Yes in S352, Yes in S353 and S354).
[0049] 5, when sheet feeding control is started in this state, the number of sheets that can be fed is cleared in step S303, and the history of no sheets becomes "none" (steps S303, S304). Next, air blowing operations are performed by air blowing units 511A, 512A on the sheet stack on sheet stacking plate 514 (S306 to S308), and the number of sheets that can be fed is set to 10 sheets as a predetermined number (S309). Further, a feeding operation is performed by sheet feeding unit 506, and thereafter, sheets are fed one by one without a new air blowing operation being performed until 10 sheets S have been fed (S310 to S312).
[0050] Then, at the timing when the 11th sheet is fed, the result in step S305 becomes No, the air blowing units 511A and 512A perform the air blowing operation, and the number of sheets that can be fed again becomes 10. Then, when the feeding operation of the remaining 5 sheets is completed, the result in step S312 becomes Yes, and the sheet feeding control ends (S315).
[0051] Next, consider a case where, for example, the number of sheets required for printing is 15, and sheet feeding control is started when a stack of eight sheets is set on the sheet stacking plate 514. That is, consider a case where a stack of eight sheets as the first sheets is stacked on the sheet stacking plate, and a job is input to feed 15 sheets, which is more than eight sheets, as the second sheets. When a stack of eight sheets is set on the sheet stacking plate 514 from a state where no sheets are stacked on the sheet stacking plate 514, the no-sheet history becomes "present" (Yes in S352, Yes in S353 and S354).
[0052] When sheet feeding control is started in this state, the number of sheets that can be fed is cleared in step S303, and the history of no sheets becomes "none" (steps S303, S304). Next, air blowing units 511A, 512A perform an air blowing operation on the sheet stack on sheet stacking plate 514 (S306 to S308), and the number of sheets that can be fed is set to a predetermined number of 10 sheets (S309). Further, a feeding operation is performed by sheet feeding unit 506, and thereafter, sheets are fed one by one without a new air blowing operation being performed until eight sheets S have been fed (S310 to S312).
[0053] Then, at the timing when the ninth sheet is fed, the result of step S313 becomes Yes, a notification screen is displayed on the display unit 730a of the operation unit 730 (S314), and the job is interrupted. This is because, when the eighth sheet is fed (S310), the absence of sheets is detected based on the sheet presence / absence sensor 401 (S352), and the sheet absence history becomes "present" (S353). In this state, when a new stack of 50 sheets is set on the sheet stacking plate 514 and the "restart job" button 731 is touched by the user, the job is resumed.
[0054] Then, the control unit 100 starts the sheet feeding control of FIG. 5 again (S301). Since the sheet stack of 50 sheets is newly set on the sheet stacking plate 514, the control unit 100 advances to step S303 and clears the number of sheets that can be fed (S303), because the sheet stack of 50 sheets is newly set on the sheet stacking plate 514 and the sheet no-sheet history is "present". Therefore, the result in step S305 is No, and the air blowing operation is performed by the air blowing units 511A and 512A on the newly set sheet stack (S306 to S308), and the number of sheets that can be fed is set to 10 sheets as a predetermined number (S309). After that, the sheets are fed one by one without performing a new air blowing operation (S310 to S312), and when 7 sheets are fed, a total of 15 sheets are fed, and the sheet feeding control ends.
[0055] As described above, in this embodiment, the air blowing operation is performed by air blowing units 511A and 512A, so that the adhesion of sheets that have a smooth surface such as coated paper and tend to have a high adhesion between sheets can be reduced. This reduces conveyance failures such as slipping of pickup roller 501 and making it impossible to convey a sheet.
[0056] In addition, since the sheet S is fed after the air blowing operations by the air blowing units 511A and 512A are stopped, skew of the sheet can be reduced. Therefore, when correcting skew of the sheet at the registration roller pair 240, the amount of skew correction required is small, so that the variation in the position of the sheet conveyed to the secondary transfer unit 201D can be reduced and the printing precision (quality) can be improved.
[0057] Furthermore, in this embodiment, when there are no more sheets supported on the sheet stacking plate 514, a blowing operation is performed on the next sheet stack supported on the sheet stacking plate 514 before the feeding operation is performed. Therefore, the feeding operation is not performed on a new sheet stack set on the sheet stacking plate 514 without blowing air, and the sheets can be fed in a state in which the uppermost sheets of the sheet stack are lifted by the air blowing operation. This reduces the adhesion between the sheets, and reduces sheet transport problems such as double feeding.
[0058] <Other embodiments> In the above embodiment, the sheet feeding control in the manual feeding section 235 having the air blowing sections 511A, 512A has been described. However, the present invention is not limited to this, and the sheet feeding control according to the present embodiment may be performed in the sheet feeding unit 230 having the feeding cassette 1 or in the feeding deck 500 having an air blowing section. In addition, when the sheet feeding control according to the present embodiment is performed in the sheet feeding unit 230, the sheet feeding control may be performed in any stage in the vertical direction. In other words, the sheet supporting section that supports the sheet stack may have any configuration.
[0059] In the above embodiment, the sheet feeding unit is provided with a pickup roller for feeding the sheets, and a feed roller and a retard roller for separating overlapped sheets, and feeding and separating the sheets is described. However, the present invention is not limited to this, and the sheet feeding unit may have any configuration for feeding the sheets, such as a unit that feeds the sheets by vacuum adsorbing the sheets to a belt or the like.
[0060] In the above embodiment, the control unit 100 is provided in the image forming apparatus 201. However, the present invention is not limited to this, and the control unit may be provided in the feeding deck 500. In other words, the control unit may be disposed in any device as long as the control unit capable of controlling the sheet feeding unit and the air blowing unit is electrically connected to them.
[0061] In the above embodiment, when there are no more sheets on the sheet stacking plate 514, the user is notified by the operation unit 730 including a liquid crystal panel, but this is not limited to the above. For example, the user may be notified of the absence of sheets by turning on an LED lamp or sounding a buzzer.
[0062] In the above embodiment, air is blown onto both sides in the width direction of the sheet stack stacked on the sheet stacking plate 514, but this is not limiting. For example, air may be blown onto only one side in the width direction of the sheet stack, or air may be blown onto the front side and rear side of the sheet stack.
[0063] In the above embodiment, the image forming apparatus 201 including the manual feed unit 235 and the control unit 100 has been described as a sheet feeding device, but the present invention is not limited to this. For example, the image forming system 600 including the feed deck 500 and the image forming apparatus 201 may be regarded as a sheet feeding device. Furthermore, the manual feed unit 235 and the control unit 100 may be regarded as a sheet feeding device.
[0064] In the above embodiment, the electrophotographic image forming apparatus 201 has been described, but the present invention is not limited to this. For example, the present invention can also be applied to an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from nozzles.
[0065] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]
[0066] 6: sheet support section (manual feed tray) / 100: control section / 201A: housing (image forming apparatus main body) / 201B: image forming section / 401: sheet presence / absence sensor / 506: sheet feeding section / 511, 512: regulation section (side end regulation plate) / 511a, 512a: blowing port (blowing nozzle) / 511b, 512b: fan / 511A, 512A: air handling section (air blowing section) / 730: operation section, notification section / FD: sheet feeding direction / WD: width direction
Claims
1. A sheet support section that supports the sheet bundle, A sheet feeding unit that contacts the uppermost sheet of the sheet bundle supported by the sheet support unit and performs a feeding operation to feed the uppermost sheet, An air blowing unit that blows air onto the side surface of a sheet bundle supported by the sheet support unit to loosen the sheets, The system includes a control unit that performs the spraying operation using the air handling unit, and after stopping the spraying operation, performs sheet feeding control by using the sheet feeding unit to feed a predetermined number of sheets while the spraying operation is stopped, In the sheet feeding control, when the sheet feeding unit is performing the feeding operation for a predetermined number of sheets, if the sheets supported by the sheet support unit run out, the control unit performs the spraying operation for the next bundle of sheets supported by the sheet support unit before performing the feeding operation. A sheet feeding device characterized by the following features.
2. The sheet presence sensor further includes a sensor that detects the presence or absence of a sheet supported by the sheet support portion. In the sheet feeding control, if the control unit determines, based on the detection result of the sheet presence sensor, that there are no more sheets supported by the sheet support unit, it will perform the spraying operation on the sheet bundle supported by the sheet support unit before performing the feeding operation. The sheet feeding device according to feature 1.
3. In the sheet feeding control, when a sheet bundle consisting of a first sheet is loaded onto the sheet support unit and a job is input to feed a second sheet which is more than the first sheet but less than the predetermined number of sheets, the control unit performs the spraying operation before performing the feeding operation after the sheet support unit runs out of sheets and the job is interrupted, a new sheet bundle is loaded onto the sheet support unit and the job is resumed. The sheet feeding device according to feature 1.
4. It further includes a control panel that can be operated by the user, The operation unit can notify the user that the job has been interrupted and can instruct the control unit to resume the job. The sheet feeding device according to feature 3.
5. It also includes a notification unit that can notify the user, The control unit, in the sheet feeding control, notifies the user via the notification unit when there are no more sheets supported by the sheet support unit. The sheet feeding device according to feature 1.
6. The enclosure is further equipped, The aforementioned sheet support is a manual feed tray that is supported by the housing so as to be openable and closable. The sheet feeding device according to feature 1.
7. The sheet support portion further comprises a regulating portion that forms the position of the side surface of the sheet bundle supported by the sheet support portion, The aforementioned air handling section is provided in the regulating section, The sheet feeding device according to feature 1.
8. The air handling unit includes a fan that sends air, and a nozzle that blows the air sent from the fan onto the side surface of the sheet bundle supported by the sheet support unit. The sheet feeding device according to feature 7.
9. The restricting portion restricts the position of the side surface in the width direction perpendicular to the sheet feeding direction of the sheet bundle supported by the sheet support portion. The sheet feeding device according to feature 7.
10. The control unit, when the number of sheets to be fed in a job is greater than the predetermined number, repeats the sheet feeding control until the number of sheets to be fed reaches the predetermined number. The sheet feeding device according to feature 1.
11. The sheet further comprises an image forming unit that forms an image. A sheet feeding device according to any one of claims 1 to 10.