Sheet feeding device

Abstract

To provide a sheet feeding device that can suppress sheets from being poorly fed.SOLUTION: A sheet feeding device comprises: a sheet supporting part that supports a sheet bundle; a sheet feeding part that performs feeding operation of feeding a topmost sheet of the sheet bundle supported by the sheet supporting part, while contacting the topmost sheet; an air processing part that performs spraying operation of spraying air to a side of the sheet bundle supported by the sheet supporting part to process the sheets; and a control part that makes the sheet feeding part perform the feeding operation while stopping the spraying operation, after the air processing part performs the spraying operation and then stops the spraying operation. In sheet feeding control, the control part makes the sheet feeding part perform feeding operation to set number of sheets preset at least in accordance with properties of the sheets supported by the sheet supporting part, after performing the spraying operation, and then performs spraying operation again.SELECTED DRAWING: Figure 9

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. 11. As shown in FIG. 11, 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, the air blowing time is constant regardless of the attributes of the sheets being fed, so that depending on the attributes of the sheets and the temperature and humidity environment, the sheets may not be properly separated by the air blowing, and there is a risk of 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 stack of sheets, 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, and the control section is characterized in that, in the sheet feeding control, after performing the blowing operation, the sheet feeding section performs the feeding operation on at least a set number of sheets that are preset in accordance with the attributes of the sheets supported by the sheet supporting section, and then performs the blowing operation again. 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] 1A is a front view showing an operation unit, FIG. 1B is a front view showing a screen of a display unit, FIG. 1C is a front view showing a screen of the display unit, and FIG. [Figure 6] 11 is a flowchart showing sheet attribute setting control. [Figure 7] 11 is a flowchart showing sheet feeding control. [Figure 8] FIG. [Figure 9] 13 is a flowchart showing a predetermined number setting control. [Figure 10] 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 11] 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 / absence sensor 401, the environment sensor 800, 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 determining 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. Environmental sensor 800 detects the temperature and humidity around manual feed tray 6.

[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 10. 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. 10 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. 10. In this case, when a conveying load occurs near the pickup roller 501 due to a difference in conveying speed or the like while the topmost sheet S1 is being conveyed 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. 10. This reduces the effect of the side end regulating plates 511 and 512 in suppressing the skew of the sheet S1, which may result in an increase in the amount of skew of the sheet S1. Therefore, in this embodiment, sheet attribute setting control, sheet feeding control, and predetermined number setting control are performed as follows.

[0036] [Sheet attribute setting control] First, the sheet attribute setting control will be described with reference to Fig. 5(a) to Fig. 6. Fig. 5(a) is a front view showing the operation unit 730, and Fig. 5(b) to (d) are front views showing each screen of the display unit 720 of the operation unit 730. Fig. 6 is a flowchart showing the sheet attribute setting control. Note that hereinafter, "sheet" is also called "paper".

[0037] As shown in FIG. 5(a), the operation unit 730 has a display unit 720, a start key 702, a stop key 703, a numeric keypad 704, an ID key 713, a clear key 715, and a reset key 716. The start key 702 is a key for instructing the start of an image forming operation. The stop key 703 is a key for instructing the interruption of an image forming operation. The numeric keypad 704 is a key used for inputting numbers. The clear key 715 is a key for clearing numbers inputted by the numeric keypad 704. The reset key 716 is a key used for returning to the default settings.

[0038] The display unit 720 is configured with a touch panel, and can display each screen shown in Fig. 5(a) to (d). The display unit 720 is also capable of creating soft keys on the screen. As shown in Fig. 5(a), the display unit 720 can display a standby screen 720a, and when the reset key 716 is pressed while another screen is displayed on the display unit 720, the display unit 720 returns to the standby screen 720a. A "paper selection" button 741 is displayed on the standby screen 720a, and when the "paper selection" button 741 is pressed by the user, the display unit 720 becomes the screen shown in Fig. 5(b).

[0039] The screen shown in FIG. 5(b) displays a paper feed stage setting area 742 and a "Next" button 744. The paper feed stage setting area 742 displays each paper feed stage of the image forming apparatus 201, that is, the location from which the sheet is fed. When any of the paper feed stages displayed in the paper feed stage setting area 742 is pressed, the button for the pressed paper feed stage is grayed out, indicating that it has been selected. In FIG. 5(b), for example, a "Manual" button 743 corresponding to the manual feed unit 235 is selected. Then, when the user presses the "Next" button 744, the display unit 720 displays the screen shown in FIG. 5(c).

[0040] The screen shown in FIG. 5C displays a paper size setting area 745 and a "Next" button 747. The paper size setting area 745 displays the sizes of paper (hereinafter referred to as paper sizes) that can be used in the paper feed stage (e.g., the manual feed unit 235) set in the paper feed stage setting area 742. When any of the paper sizes displayed in the paper size setting area 745 is pressed, the button for the pressed paper size is grayed out, indicating that it has been selected. In FIG. 5C, for example, an "A3" button 746 corresponding to A3 size is selected. By selecting any of the paper sizes displayed in the paper size setting area 745, the paper size set in the paper feed stage set in the paper feed stage setting area 742 can be specified. Then, when the "Next" button 747 is pressed by the user, the display unit 720 displays the screen shown in FIG. 5D.

[0041] The screen shown in FIG. 5(d) displays a paper type setting area 748 and an "OK" button 749. The paper type setting area 748 displays the types of paper (hereinafter referred to as paper types) that can be used in the paper feed tray (e.g., manual feed unit 235) set in the paper feed tray setting area 742. When any of the paper types displayed in the paper type setting area 748 is pressed, the button for the pressed paper type is grayed out, indicating that it has been selected. In FIG. 5(d), for example, a "Coated Paper 1" button 749 corresponding to Coated Paper 1 is selected. By selecting any of the paper types displayed in the paper type setting area 748, the paper type set in the paper feed tray set in the paper feed tray setting area 742 can be specified.

[0042] Then, when the user presses the "OK" button 750, the sheet attribute setting control for setting the sheet attributes ends. The sheet attributes include the paper size, paper type, and paper (sheet) basis weight. For example, "Coated Paper 1" means "Single-sided Coated 1" shown in the table of FIG. 8, and has a basis weight of 163 g / m 2This refers to the single-sided coated paper described below. Although the screen shown in Fig. 5(d) does not show buttons for selecting double-sided coated paper or waterproof paper, these double-sided coated paper and waterproof paper can also be selected. Pressing the "Back" button shown in Figs. 5(b) to (d) causes the display unit 720 to display the previous screen.

[0043] Next, the sheet attribute setting control will be described with reference to the flowchart in Fig. 6. As shown in Fig. 6, the control unit 100 starts the sheet attribute setting control when the "paper selection" button 741 shown in Fig. 5(a) is pressed (S201). Then, the control unit 100 determines whether any of the paper feed stages in the paper feed stage setting area 742 shown in Fig. 5(b) has been pressed (S202).

[0044] If any of the feed trays in the feed tray setting area 742 is pressed (Yes in S202), the control unit 100 judges whether the feed tray setting is complete (S203). That is, in step S203, the control unit 100 judges whether the "Next" button 744 shown in Fig. 5(b) is pressed. If the feed tray setting is not complete (No in S203), the control unit 100 returns to step S202.

[0045] When the paper feed tray setting is completed (Yes in S203), the control unit 100 judges whether or not any paper size has been pressed in the paper size setting area 745 shown in FIG. 5(c) (S204). When any paper size has been pressed in the paper size setting area 745 (Yes in S204), the control unit 100 judges whether or not the paper size setting is completed (S205). That is, in step S205, the control unit 100 judges whether or not the "Next" button 747 shown in FIG. 5(c) has been pressed. When the paper size setting is not completed (No in S205), the control unit 100 returns to step S204.

[0046] When the paper size setting is completed (Yes in S205), the control unit 100 judges whether or not any paper type in the paper type setting area 748 shown in FIG. 5(d) has been pressed (S206). When any paper type in the paper type setting area 748 has been pressed (Yes in S206), the control unit 100 judges whether or not the selection of the paper type is completed (S207). That is, in step S207, the control unit 100 judges whether or not the "OK" button 750 shown in FIG. 5(d) has been pressed. When the paper type setting is not completed (No in S207), the control unit 100 returns to step S206.

[0047] When the paper type setting is completed (Yes in S207), the control unit 100 stores paper information related to the attributes of the sheets set and selected in steps S202, S204, and S206 in the RAM 103 (S208), and ends the sheet attribute setting control (S209). In this way, the control unit 100 can set the attributes of the sheet supported on the manual feed tray 6 based on the operation of the operation unit 730. When the sheet attribute setting control is completed, the display unit 720 displays a standby screen 720a shown in FIG. 5(a).

[0048] After the paper information is saved in RAM 103, when start key 702 on operation unit 730 is pressed, the job is started and sheet S is fed from the paper feed tray selected in the paper information. It is not necessary to set the paper information every time before starting a job. For example, if a job is executed after the paper information is saved in RAM 103 and it is desired to execute the job again based on the same paper information, it is sufficient to simply press start key 702.

[0049] [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. 7. FIG. 7 is a flowchart showing the sheet feeding control. When printing is started in the image forming apparatus 201, the control unit 100 starts the sheet feeding control to feed a sheet (S301). Then, the control unit 100 first determines whether the number of sheets that can be fed is greater than 0, that is, whether or not there is one sheet or more (S302). If the number of sheets that can be fed is greater than 0 (Yes in S302), the control unit 100 proceeds to step S307.

[0050] On the other hand, if the number of sheets that can be fed is 0 (No in S302), the control unit 100 drives the fan motors 511M and 512M, and starts an air blowing operation in which the air blowing units 511A and 512A blow air onto the sides of the sheet stack (S303). As a result, several to several tens of sheets S at the top of 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.

[0051] Since the fan motors 511M, 512M start rotating from a stopped state, a predetermined time, such as 10 seconds, is set in advance 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 S304), and when the predetermined time has elapsed (Yes in S304), the control unit 100 stops the air blowing operation (S305), that is, turns off the drive of the fan motors 511M, 512M.

[0052] As a result, the sheets S, which were in a floated state, attempt to return to the state of the sheet stack 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 stack before floating. Since the adhesive force between the sheets remains reduced until the sheet stack returns to the state of the sheet stack before floating, it is possible to feed even a sheet stack with high adhesive force while suppressing double feeding. Since it is now possible to feed the sheet stack while suppressing double feeding, the control unit 100 sets the number of sheets that can be fed to a predetermined number (step S306). The predetermined number as the set number is set in the predetermined number setting control, which will be described later with reference to FIG. 9.

[0053] The number of sheets that can be fed corresponds to the number of sheets that can be fed by the manual feed unit 235 without double feeding after the air blowing operation, until the air between the sheets is released and the sheet stack returns to its state before floating. The number of sheets that can be fed is cleared when the power of the image forming apparatus 201 is turned on from off.

[0054] Next, the control unit 100 starts the feeding operation of the sheet S (S307). 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, thereby feeding the sheet S. Thereafter, in the case where the sheets S are fed in a double state in a separation unit composed 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.

[0055] When one sheet S is fed, the control unit 100 decrements the number of sheets that can be fed by -1 (subtracts 1) (S308). Then, the control unit 100 determines whether or not feeding of the required number of sheets S required for printing has been completed (S309). When feeding of the required number of sheets has been completed (Yes in S309), the sheet feeding control by the manual feed unit 235 ends (S310). The required number is, for example, the number of sheets to be printed specified in the job.

[0056] If the required number of sheets S has not been fed (No in S309), control unit 100 returns to step S302. Then, control unit 100 continues to feed sheets S (S302 to S309) and performs the air blowing operation (S302 to S305) every time a predetermined number of sheets are fed. In this way, when feeding the required number of sheets S, control unit 100 performs the sheet S feeding operation and the air blowing operation as long as the sheet stack stacked on sheet stacking plate 514 of manual feed tray 6 remains.

[0057] [Setting control for the number of sheets] Next, the predetermined number setting control will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a diagram showing a handling number correspondence table for acquiring the handling number based on the paper information and the environmental information. Fig. 9 is a flowchart showing the predetermined number setting control.

[0058] As described above, when the air blowing units 511A and 512A perform the air blowing operation, the top several to several tens of sheets in the sheet stack are separated and floated up as shown in FIG. 4, and the adhesion between these floated sheets is reduced. However, the number of sheets that float up varies depending on the attributes of the sheets, such as the thickness and weight of the sheets. In addition, the amount of moisture contained in the sheets changes depending on the environment, such as the surrounding temperature and humidity, and the weight of the sheets also changes. Therefore, by performing the predetermined number setting control described below, it is possible to set the predetermined number according to the attributes of the sheets and the detection result of the environment sensor 800.

[0059] As shown in Fig. 9, the control unit 100 starts the predetermined number setting control in conjunction with the implementation of step S306 in Fig. 7 (S401). First, the control unit 100 acquires the paper information stored in the RAM 103 in the sheet attribute setting control (see Fig. 6) (S402). Next, the control unit 100 acquires environmental information related to the temperature and humidity around the manual feed tray 6 based on the detection result of the environmental sensor 800 (S403). The environmental information may be stored in the RAM 103.

[0060] Then, the control unit 100 refers to the separation number correspondence table shown in FIG. 8 and judges whether the search for the separation number that matches the paper information and the environmental information is completed (S404). The separation number correspondence table is stored in, for example, the ROM 102. In FIG. 8, "HH", "NN", and "NL" indicate the range of environmental information. "HH" indicates a high temperature and high humidity environment, for example, an environment with a temperature of 30°C or higher and a humidity of 80% or higher. "NN" indicates a medium temperature and medium humidity environment, for example, an environment with a temperature in the range of 23.5±5°C and a humidity in the range of 50±10%. "NL" indicates a medium temperature and low humidity environment, for example, an environment with a temperature in the range of 23.5±5°C and a humidity in the range of 15±10%.

[0061] For example, if "single-sided coated 1" is specified in the paper information and "HH" is specified in the environmental information, the number of sheets to be handled is 10. When the search for the number of sheets to be handled that matches the paper information and environmental information is complete (Yes in S404), the control unit 100 sets the number of sheets to be handled (=N sheets) searched for in step S404 as the predetermined number (S405). This ends the control for setting the predetermined number (S406).

[0062] Here, if "single-sided coated 2" is specified in the paper information and "HH" is specified in the environmental information, the predetermined number of sheets is 9. That is, in the case of the same paper type, the control unit 100 determines the first basis weight (163 g / m 2 When a sheet having a second basis weight (164 g / m or less) is supported on the manual feed tray 6, the predetermined number is set to 10 as the first number. 2 More than 220g / m 2 When a sheet having a diameter of 100 mm or less (below) is supported on the manual feed tray 6, the predetermined number is set to 9 sheets, which is a second number less than the first number. In this way, for the same paper type, the larger the basis weight, the heavier the sheet becomes and the more difficult it is to float up by the air blowing operation, so the predetermined number tends to be smaller.

[0063] The values ​​of the predetermined number and the number of sheets to be handled are not limited to the values ​​shown as examples in this embodiment. The predetermined number setting control may be performed at any time before the start of sheet feeding (S307) without being limited to step S306. For example, the predetermined number setting control may be performed when a job is input and the sheet feeding control starts (S301).

[0064] 8, in this embodiment, the sheet feeding control shown in FIG. 7 is executed for coated paper or waterproof paper, that is, the sheet feeding control including the air blowing operation in which air is blown onto the sides of the sheet stack by air blowing units 511A, 512A. On the other hand, for thin paper, plain paper or thick paper, another sheet feeding control is executed in which the sheet feeding unit 506 performs the feeding operation without performing the blowing operation by air blowing units 511A, 512A. Note that thin paper, plain paper and thick paper are uncoated paper, and thin paper has a basis weight of, for example, 52 to 63 g / m. 2 For example, plain paper has a basis weight of 64 to 105 g / m 2 For example, cardboard has a basis weight of 106 to 163 g / m 2 This is a sheet.

[0065] 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.

[0066] 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.

[0067] In this embodiment, an appropriate "predetermined number" can be set according to the attributes of the sheets supported on the manual feed tray 6 and the detection result of the environment sensor 800. Then, in the sheet feeding control, the control unit 100 performs the air blowing operation by the air blowing units 511A and 512A, and then performs the feeding operation on the predetermined number of sheets by the sheet feeding unit 506, and then performs the blowing operation again. This makes it possible to appropriately reduce the adhesion between the sheets by the air blowing operation, and to reduce sheet conveyance failures such as double feeding.

[0068] <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.

[0069] 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.

[0070] 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.

[0071] In the above embodiment, the predetermined number is set based on the paper information and the environmental information, but the present invention is not limited to this. For example, the predetermined number may be set based only on the paper information without using the environmental information. That is, in the sheet feeding control, after the air blowing operation by the air blowing units 511A and 512A is performed, the feeding operation is performed on a predetermined number of sheets that are set in advance according to the attributes of at least the sheets supported by the manual feed tray 6, and then the air blowing operation is performed again.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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]

[0076] 6: sheet support section (manual feed tray) / 100: control section / 201A: housing (image forming apparatus main body) / 201B: image forming section / 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 / 800: environment sensor / 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 sheet feeding control, which involves performing the spraying operation using the air handling unit, stopping the spraying operation, and then performing the sheet feeding operation using the sheet feeding unit to feed a predetermined number of sheets while the spraying operation is stopped, The control unit determines the predetermined number of sheets according to the attributes of the sheets. A sheet feeding device characterized by the following features.

2. The attributes of the sheet include the type of sheet, The sheet feeding device according to feature 1.

3. The control unit sets the predetermined number to a first number when the sheet supported by the sheet support is single-sided coated paper, and sets the predetermined number to a second number which is greater than the first number when the sheet supported by the sheet support is double-sided coated paper. The sheet feeding device according to feature 2.

4. The control unit executes the sheet feeding control when the sheet supported by the sheet support is coated paper or water-resistant paper, and executes another sheet feeding control that executes the feeding operation without executing the spraying operation when the sheet supported by the sheet support is plain paper. The sheet feeding device according to feature 2.

5. The attributes of the aforementioned sheet include the basis weight of the sheet. The sheet feeding device according to feature 1.

6. The control unit sets the predetermined number to a third number when the sheet supported by the sheet support has a first basis weight, and sets the predetermined number to a fourth number which is less than the third number when the sheet supported by the sheet support has a second basis weight which is greater than the first basis weight. The sheet feeding device according to feature 5.

7. It further includes a control panel that can be operated by the user, The control unit determines the predetermined number of sheets based on the attributes of the sheets set via the operation unit. The sheet feeding device according to feature 1.

8. The enclosure is further equipped, The seat support portion is provided on the side of the housing and is configured to be rotatable relative to the housing. The sheet feeding device according to feature 1.

9. A regulating member that is movable in a width direction perpendicular to the sheet feeding direction of the sheet bundle supported by the sheet support member, and further comprises a regulating member that regulates the position of the side surface of the sheet bundle supported by the sheet support member, The air handling section moves in conjunction with the movement of the restricting section in the width direction. The sheet feeding device according to feature 1.

10. A sheet support portion that supports a 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, A detection unit for detecting the temperature and humidity around the sheet support portion, The system includes a control unit that performs sheet feeding control, which involves performing the spraying operation using the air handling unit, stopping the spraying operation, and then performing the sheet feeding operation using the sheet feeding unit to feed a predetermined number of sheets while the spraying operation is stopped, The control unit determines the predetermined number of sheets according to the detection result of the detection unit. A sheet feeding device characterized by the following features.

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.

Images