Paper feeder, image forming system, and control program

Abstract

To stably perform a sheet feeding.SOLUTION: A sheet feeding device 10 includes: a placement part 331 for stacking a plurality of sheets; an air supply part 31 including a tip fan 311 that generates an air flow directed the sheet from a tip end side in a sheet feeding direction of the sheets stacked on the placement part 331; an adsorption conveyance part 32 that adsorbs and conveys the uppermost sheet separated from a bundle of sheet stacked by the air supply part 31; a detection part that detects the amount of feeding that is conveyed along with the next sheet when the uppermost sheet is conveyed by the adsorption conveyance part 32; and a control section 11, the control part 11 controls the air volume of the tip fan 311 so that the air volume of the tip fan 311 increases as the entrainment amount detected by the detection part increases.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a paper feeder, an image forming system, and a control program. [Background technology]

[0002] Copiers, facsimiles, printers, and image forming systems equipped with these functions are equipped with a paper feed unit that separates and feeds out sheets of paper stored in the paper feed unit one by one, and transports the sheets to an image forming unit where images are formed.

[0003] In recent years, electrophotographic image forming systems have come to be used in the field of light printing such as POD (print on demand), and there is a demand for systems that can meet a variety of needs regarding image quality and paper. In particular, gloss coated paper, fine paper, overprinted paper, recycled paper, etc. may be used.

[0004] In conventional roller-conveyance paper feeders, paper is transported by the friction between the paper and the roller surface, but with gloss-coated paper, which has a very smooth surface, sufficient friction is not obtained, resulting in unstable paper feeding. Furthermore, with overprinted paper or recycled paper, foreign matter such as release agent (dusting powder) and paper dust adhering to the surface is transferred to the roller surface, reducing the friction and resulting in the problem of unstable paper feeding over the long term.

[0005] To address these issues, an air-assisted paper feeder (hereinafter also referred to as an air paper feeder) has been proposed (see, for example, Patent Document 1). This air paper feeder blows air from the periphery toward the upper side of a stack of sheets stacked on a paper feed tray, sending air between the sheets to lift and separate the topmost sheet from the stack. The separated topmost sheet is then transported one by one by a paper feed roller or the like.

[0006] In the air paper feeder of Patent Document 1, paper feed parameters are set based on paper type information for the paper being used, and the transport results under those paper feed parameters are collected in a management device connected to the network and analyzed to set (update) the paper feed parameters. Also, in this air paper feeder, the air volume of the fan that blows air onto the paper is adjusted as a paper feed parameter based on the transport results such as the amount of early feed and the number of jams, and the adjusted settings are used in common for each image forming device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2020-70166 A (particularly Figures 12 and 13) Summary of the Invention [Problem to be solved by the invention]

[0008] However, as in Patent Document 1, if a single setting is always used based on the amount of lead feed, even if a setting that was appropriate for one day's feeding is applied to another day, for example, if the environment inside the machine changes daily, stable paper feeding may not be achieved. Furthermore, for light paper with a small basis weight, the paper's posture varies greatly when air is blown. As a result, the handling performance changes depending on the paper's posture, which in turn changes the amount of lead feed and the frequency of jams. As a result, paper feeding problems cannot be consistently reduced. Furthermore, Patent Document 1 uniformly controls the airflow of multiple types of fans installed in the paper feed tray, and does not reflect the characteristics of each fan.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a paper feeding device that can stably feed paper by controlling the air volume of the tip fan to increase as the detected amount of paper advance increases, and a control program that executes paper feeding processing. [Means for solving the problem]

[0010] The above object of the present invention can be achieved by the following means.

[0011] (1) a stacking section for stacking a plurality of sheets of paper; an air supply unit including a leading end fan that generates an air flow from a leading end side of the paper in a paper feed direction of the paper stacked on the stacking unit toward the paper; a suction conveyance unit that uses the air supply unit to suction and convey the topmost sheet separated from the stack of sheets; a detection unit that detects an amount of accompanying transport of the next sheet when the uppermost sheet is transported by the suction transport unit; a control unit, The control unit controls the air volume of the front end fan so that the air volume of the front end fan increases as the amount of early feed detected by the detection unit increases.

[0012] (2) The air supply unit further includes a side fan that generates an air flow toward the paper from a side perpendicular to the paper feed direction of the paper stacked in the stacking unit, The control unit controls the air volume of the front fan and the side fan so that the greater the amount of paper advance detected by the detection unit, the greater the air volume of the front fan and the smaller the air volume of the side fan.

[0013] (3) A lower limit value of the air volume of the side fan is set in advance, The paper feeding device according to (2) above, wherein the control unit controls the air volume of the side fan so that it does not fall below the lower limit value.

[0014] (4) The paper feeding operation includes a first stage in which the topmost paper sheet is lifted from the stack of paper sheets loaded in the stacking section and adsorbed to the adsorption conveying section, and a second stage in which the paper sheet adsorbed to the adsorption conveying section is conveyed downstream after the first stage, The control unit controls the air volume of the tip fan by: A paper feeding device described in any one of (1) to (3) above, wherein the front fan is controlled so that the air volume from the front fan in the second stage increases as the amount of early feeding detected by the detection unit increases.

[0015] (5) A switching mechanism is further provided for switching the direction of the airflow from the tip fan between a downward direction toward the top sheet of the stack of sheets loaded in the stacking section and an upward direction toward the suction conveying section disposed above the stack of sheets loaded in the stacking section, The control unit In the first stage, the direction of the airflow is set to a downward direction by the switching mechanism, In the second stage, the switching mechanism sets the direction of the air flow in an upward direction, and the tip fan is controlled so that the greater the amount of paper advance detected by the detection unit, the greater the air volume from the tip fan.

[0016] (6) When the control unit continuously feeds the sheets stacked in the stacking unit one by one, A paper feeding device as described in any one of (1) to (5) above, wherein after the front end fan is started, the air volume control is performed according to the amount of lead-in feed of the front end fan during the period until the amount of lead-in feed decreases to a predetermined amount or less.

[0017] (7) When the control unit continuously feeds the sheets stacked in the stacking unit one by one, A paper feeding device described in any of (1) to (6) above, which performs the air volume control according to the amount of paper advance after starting the front fan until a predetermined number of sheets have been fed or until a predetermined time has passed.

[0018] (8) Further, an acquisition unit is provided to acquire paper information about the paper loaded in the stacking unit, A paper feeding device described in any one of (1) to (7) above, wherein the control unit performs the air volume control using a correction table or a relational equation that shows the relationship between the paper information, the amount of early feed, and the fan air volume or correction amount, which is pre-stored in a memory unit.

[0019] (9) A paper feeding device described in any one of (1) to (8) above, wherein the detection unit detects the distance transported downstream in the paper feeding direction when the previous paper is transported by the suction transport unit as the amount of early feed.

[0020] (10) The detection unit includes a paper detection sensor that detects the presence or absence of paper at a predetermined position on the conveyance path downstream of the suction conveyance unit, The paper feeding device described in (9) above, wherein the control unit calculates the amount of early feed based on the amount of transport from the start of driving the suction transport unit until the paper reaches the specified position, or the arrival time, when feeding paper.

[0021] (11) A paper feeder according to any one of (1) to (10) above; an image forming unit that forms an image on the paper fed from the paper feeding device; An image forming system comprising:

[0022] (12) A control program for controlling a paper feed device including a loading section for loading a plurality of sheets of paper, an air supply section including a leading end fan for generating an air flow directed from the leading end of the sheets of paper loaded on the loading section in the paper feed direction toward the sheets, an adsorption transport section for adsorbing and transporting the topmost sheet separated from the stack of sheets by the air supply section, and a detection section for detecting an amount of accompanying transport of the next sheet when the topmost sheet is transported by the adsorption transport section, A step (a) of detecting an amount of early feed by the detection unit; and (b) controlling the air volume of the tip fan in accordance with the amount of lead-in movement detected in (a), In step (b), a control program is provided for causing a computer that controls a paper feeding device to execute a paper feeding process in which the air volume of the tip fan is controlled so that the air volume of the tip fan increases as the amount of paper advance detected in step (a) increases.

[0023] (13) The air supply unit further includes a side fan that generates an air flow toward the paper from a side of the paper stacked in the stacking unit that is perpendicular to the paper feed direction, The control program described in (12) above, wherein in step (b), the air volume of the side fan is also controlled in accordance with the detected amount of accompanying movement, and the air volumes of the tip fan and the side fan are controlled so that the larger the amount of accompanying movement detected by the detection unit, the larger the air volume of the tip fan and the smaller the air volume of the side fan. [Effects of the Invention]

[0024] A paper feeder according to the present invention includes a stacking section for stacking multiple sheets of paper, an air supply section including a leading edge fan that generates an airflow directed from the leading edge of the sheets stacked on the stacking section in the paper feed direction toward the sheets, a suction transport section that sucks and transports the topmost sheet separated from the stack of sheets by the air supply section, a detection section that detects the amount of lead-in feed by which the next sheet is carried along when the topmost sheet is transported by the suction transport section, and a control section, wherein the control section controls the air volume of the leading edge fan so that the larger the amount of lead-in feed detected by the detection section, the greater the air volume of the leading edge fan, thereby reducing the amount of lead-in feed and ultimately enabling stable paper feeding. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram showing a schematic configuration of an image forming system including a paper feeder according to an embodiment of the present invention; [Figure 2] FIG. 1 is a block diagram of an image forming system. [Figure 3] FIG. 2 is a cross-sectional view of a paper feed unit of the paper feed device. [Figure 4]FIG. [Figure 5A] FIG. 10 is a schematic diagram showing a paper feeding operation (first stage). [Figure 5B] FIG. 10 is a schematic diagram showing the paper feeding operation (second stage). [Figure 5C] FIG. 10 is a schematic diagram showing the feeding operation (first stage) of the next sheet when there is no early feeding. [Figure 6A] FIG. 10 is a schematic diagram showing a paper feeding operation (first stage). [Figure 6B] FIG. 10 is a schematic diagram showing the paper feeding operation (second stage). [Figure 6C] FIG. 10 is a schematic diagram showing the feeding operation (first stage) of the next sheet when early feeding occurs. [Figure 7] 10 is a graph showing the relationship between the amount of lead airflow and the air volume of the tip fan. [Figure 8] 10 is a graph showing the relationship between the amount of airflow and the air volume of a side fan. [Figure 9] 5 is a flowchart showing a paper feeding process of the paper feeding device in the first embodiment. [Figure 10] 10 is a subroutine flowchart showing the processing of step S14. [Figure 11] FIG. 10 is a schematic diagram for explaining a method for calculating an amount of early feed. [Figure 12] 10 is a subroutine flowchart showing the processing of step S15. [Figure 13] 10 is an example of a correction table showing the relationship between the amount of early feed and the air volume of the fan. [Figure 14] 10 is a subroutine flowchart showing the processing of step S14 in a modified example. [Figure 15] 10 is an example of a correction table showing the relationship between paper information, early feed amount, and correction amount (for the tip fan) in a modified example. [Figure 16] 10 is a flowchart showing a paper feeding process of a paper feeding device in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the scope of the present invention is not limited to the disclosed embodiments. In the description of the drawings, identical elements are designated by the same reference numerals, and redundant description will be omitted. Furthermore, the dimensional proportions in the drawings are exaggerated for convenience of explanation and may differ from the actual proportions. In the drawings, the vertical direction is designated as the Z direction, the front and rear directions of the image forming apparatus are designated as the Y direction, and the direction perpendicular to these Y and Z directions is designated as the X direction. The Y direction is also referred to as the width direction or rotation axis direction, and the X direction is also referred to as the conveyance direction (or paper feed direction). In this embodiment, paper includes printing paper (hereinafter simply referred to as paper) and various films. In particular, paper includes paper made from plant-derived mechanical pulp and / or chemical pulp. Furthermore, types of paper include coated glossy paper and matte paper, as well as uncoated plain paper and fine paper.

[0027] 1 is a diagram showing a schematic configuration of an image forming system 1000 including a sheet feeding device 10 according to this embodiment.

[0028] The image forming system 1000 includes a paper feeder 10 and an image forming apparatus 50. The paper feeder 10 and the image forming apparatus 50 are mechanically coupled to each other and electrically connected by a cable 80 or the like.

[0029] (Paper feeder 10) The paper feeder 10 includes a control unit 11, a storage unit 12, a communication unit 13, and one or more paper feed units 30. The paper feeder 10 feeds and transports paper sheets 90 stored in the paper feed unit 30 one by one, and sends them to the downstream image forming device 50. The paper feed unit 30 is an air-assisted paper feed unit, and is also called a paper feed tray. The specific configuration of the paper feed unit 30 will be described in detail later (see FIG. 3, etc.).

[0030] The control unit 11 has a CPU and a memory. The CPU is a control circuit composed of a multi-core processor or the like that controls the above-mentioned components and executes various arithmetic processes according to a program, and each function of the sheet feeding device 10 is realized by the CPU executing the corresponding program. The memory is a high-speed accessible main storage device that temporarily stores programs and data as a working area. The memory may be, for example, a DRAM, SDRAM, or SRAM.

[0031] The memory unit 12 is a large-capacity auxiliary storage device that stores various programs including the operating system and various data. For example, a hard disk, a solid state drive, a flash memory, a ROM, etc. are used as the storage. The memory unit 12 stores paper information about the paper 90 stored in the paper feed unit 30, as well as a correction table or relational equation used for paper feed control, which will be described later. This paper information is acquired from the image forming device 50 by the communication unit 13, which functions as an acquisition unit. On the image forming device 50 side, this paper information is generated from the detection output of the built-in media sensor or user input from the operation display unit 57. The paper information includes the size, basis weight, and paper type of the paper. Basis weight classifications include 62 g / m 2 ~450g / m 2 The range is from several to a dozen or so divided at arbitrary intervals. Paper type classifications include, for example, gloss paper, matte paper, plain paper, high-quality paper, and high-gloss paper. The correction table or relational expression indicates the relationship between the "leading feed amount" and the fan airflow (or fan correction amount), or indicates the "leading feed amount," paper information, and fan airflow (or fan correction amount) (see Figure 13 or Figure 15, described below).

[0032] The communication unit 13 is an interface for communicating with devices such as the image forming device 50 .

[0033] (Image forming device 50) Image forming apparatus 50 includes control unit 51, memory unit 52, communication unit 53, image forming unit 54, paper feed unit 55, conveyance unit 56, operation display unit 57, image reading unit 58, etc. Hereinafter, paper feed unit 55 will also be referred to as main body paper feed unit 55 to distinguish it from paper feed unit 30 of paper feed device 10.

[0034] Control unit 51 is configured with a CPU and memory, similar to control unit 11 described above, and controls image forming apparatus 50. Alternatively, control unit 51 cooperates with control unit 11 of sheet feeder 10 to control the entire image forming system.

[0035] The storage unit 52 has the same configuration as the storage unit 12 and stores various data. The communication unit 53 is an interface for communicating with devices such as the sheet feeding device 10. The communication unit 53 also communicates with a PC or the like via a network.

[0036] Image forming unit 54 is, for example, an electrophotographic image forming unit, and includes a photosensitive drum, a charging electrode, an exposure unit, a developing unit, a transfer unit, a cleaning unit, etc. The electrostatic latent image formed on the photosensitive drum is developed into a toner image by the developing unit. Paper 90 transported from paper feed unit 30 or main body paper feed unit 55 is timing-controlled by registration rollers and transported to the transfer unit in synchronization with the toner image. Paper 90 with the toner image transferred in the transfer unit is transported to the downstream fixing unit, where the toner image is fixed on paper 90.

[0037] Main body side paper feed unit 55 is a roller conveyance type paper feed unit that feeds and conveys paper one sheet at a time by using the frictional force between paper 90 and the roller surface. Note that main body side paper feed unit 55 may also be an air-assisted type paper feed unit similar to paper feed unit 30, and the paper feeding process described below may be applied.

[0038] The transport section 56 includes a transport path on which a plurality of transport rollers are arranged, and transports the paper 90 fed from each of the paper feed sections 30 and 55 .

[0039] The operation display unit 57 is equipped with a touch panel, a numeric keypad, a start button, a stop button, etc., and displays the status of the image forming system 1000 and accepts print instructions from the user. It also accepts input of paper information from the user, such as the type and basis weight of paper placed in the paper feed units 30, 55, etc.

[0040] Image reading unit 58 is located on top of the main body and includes a sensor array, an optical system, an LED light source, a document glass, and a housing to house these components. Image reading unit 58 reads a document transported by the ADF or a document placed on the document glass and generates image data.

[0041] (Paper feed section 30) Next, the configuration of the paper feed unit 30 will be described with reference to Figures 3 and 4, along with Figure 2. Figures 3 and 4 are a cross-sectional view and a perspective view of the paper feed unit 30, respectively.

[0042] The paper feed section 30 includes an air supply section 31, a suction conveyance section 32, a paper storage section 33, a switching mechanism 34, a conveyance section 35, and a plurality of paper detection sensors S1 to S3.

[0043] Air supply unit 31 is composed of tip fan 311, side fan 312, and ducts 313 and 314. Tip fan 311 and side fan 312 can control the air volume in multiple stages. In the following description, each of fans 311 and 312 will be described as being able to vary the air volume within a range of 0 to 100% according to an input PWM value (0 to 100%). Furthermore, when controlling the air volume, the two side fans 312 arranged on each side are variably controlled to have the same output.

[0044] Duct 313 is arranged at the leading edge of a stack of paper sheets 90 (hereinafter simply referred to as a paper stack) stacked on loading section 331 (described later) of paper storage section 33. Leading edge fan 311 inside duct 313 generates an airflow directed from the leading edge in the paper feed direction toward the paper stack (paper sheets). The airflow is exhausted from air outlet a1 provided at the top of duct 313.

[0045] Ducts 314 are provided on both sides of the paper stack in the width direction. Side fans 312 inside duct 314 generate airflows toward the paper stack from both side surfaces. The airflows are discharged toward the top of the paper stack from air outlets a2 provided at the top of duct 314. In the stage where paper sheet 90 is separated from the paper stack and floated up (first stage in FIG. 5A described below), paper sheet 90 is separated from the paper stack and floated up by the airflows directed approximately horizontally toward the top of the paper stack generated by leading edge fan 311 and side fans 312. Of the floated paper sheets 90, the topmost paper sheet 90 is adsorbed by adsorption transport unit 32 and transported in the paper feed direction.

[0046] The suction conveying section 32 is disposed above the downstream side (the leading edge side of the paper) in the conveying direction of the paper stack. Note that in Figure 3 and other figures, the length of the suction conveying section 32 in the conveying direction is exaggerated to be equivalent to the length of the paper 90.

[0047] The suction conveying unit 32 includes a suction fan 321, a duct 322, a suction belt 323, multiple conveying rollers, and a drive motor 329. As shown in FIG. 4, multiple suction belts 323 (three in the example of FIG. 4) are arranged in parallel across the width. These endless suction belts 323 are rotatably supported by a large-diameter roller connected to the drive motor 329 and two smaller-diameter rollers. The suction belt 323 has multiple small-diameter through-holes. A suction port facing the suction belt 323 is provided at the bottom of the duct 322, and the suction fan 321 creates a negative pressure inside the suction belt 323. Air sucked in by the suction fan 321 is discharged to the rear side of the device via the duct 322.

[0048] The paper storage section 33 includes a loading section 331 with its upper surface on a horizontal plane, a leading edge restriction plate 332, a pair of side restriction plates 333, a trailing edge restriction plate 334, and an elevation motor 339. The positions of the side restriction plate 333 and the trailing edge restriction plate 334 can be changed by the user using a movement mechanism (not shown) depending on the size of the paper 90 to be stored, and the leading edge restriction plate 332, the side restriction plate 333, and the trailing edge restriction plate 334 are positioned so that the inner surfaces of the leading edge restriction plate 332, the side restriction plate 333, and the trailing edge restriction plate 334 are in approximate contact with the four sides of the stack of paper to be stored. The side restriction plate 333 and the above-mentioned duct 314 are integrally configured, and the duct 314 is formed inside the side restriction plate 333, and the side fan 312 is housed therein.

[0049] Each paper detection sensor S1 is configured as an optical sensor alone or in combination with an actuator. The paper detection sensor S1 detects the presence or absence of paper 90 at the detection position (Z direction).

[0050] The paper detection sensor S1 detects that the top of the stack of paper sheets placed on the loading surface of the loading section 331 of the paper storage section 33 has reached a predetermined height position, and in response to this output, the control section 11 controls the lifting motor 339 to adjust the height of the loading section 331 so that the top of the stack of paper sheets is at the predetermined height position.

[0051] Switching mechanism 34 is made up of shutter 341, air direction switching solenoid 349, and other connecting members (not shown). Shutter 341 is arranged inside duct 313, and by operating shutter 341 with air direction switching solenoid 349, the direction of airflow from tip fan 311 is switched between upward and downward. Note that instead of shutter 341 and the solenoid, a plate-shaped air direction switching plate and a drive motor may be used, allowing the air direction to be changed in multiple stages instead of just two.

[0052] When shutter 341 is in the initial position and a downward airflow is formed (FIG. 5A, described later), a substantially horizontal airflow is formed toward the top of the stack of sheets. Furthermore, when control unit 11 operates airflow direction switching solenoid 349 to change the position of shutter 341 and a state in which an upward airflow is formed (FIG. 5B, described later), a diagonally upward airflow is formed toward suction conveyance unit 32, which is positioned above the stack of sheets. When airflow direction switching solenoid 349 is turned off, shutter 341 returns to the initial position by a spring or the like.

[0053] Conveyance section 35 includes one or more pairs of conveyance rollers, and conveys downstream paper 90 that has been fed and conveyed by suction conveyance section 32. Paper detection sensors S2 and S3 detect that paper 90 has been properly conveyed to a predetermined position on the conveyance path.

[0054] (Paper feeding operation and leading amount) Next, the paper feeding operation and the amount of early feed by the paper feeding unit 30 described above will be described with reference to Figures 5A to 6C. Figures 5A to 5C are schematic diagrams showing ideal paper feeding operations in a time series when there is no early feed (advance feed amount = 0 (mm)). Figures 6A to 6C are schematic diagrams showing paper feeding operations in a time series when there is early feed (advance feed amount X mm). In Figures 5A to 6C, the first to third sheets of paper at a given time are represented as sheets 90a to 90c, respectively. Each time paper feeding device 10 feeds one sheet of paper 90, it repeats the following first stage (paper floating) and second stage (transport and separation) of paper feeding operations.

[0055] In the first stage of paper feeding operation shown in FIG. 5A, the top sheet 90a of the paper stack is lifted by the approximately horizontal airflow generated by the leading edge fan 311 and the side fan 312, and the lifted sheet 90a is then adsorbed to the surface of the adsorption belt 323 by the suction fan 321. A detection sensor (not shown) may be configured to detect that the sheet 90a has been adsorbed to the adsorption belt 323. In the first stage shown in FIG. 5A, the shutter 341 is in the initial position, and the leading edge fan 311 creates a downward airflow. The downward airflow has the function of separating the topmost sheet 90 by sending air between the sheets 90 of the paper stack. The first stage ends a predetermined time after adsorption of the sheet 90 to the adsorption belt 323 is detected, or a predetermined time after the first stage begins after the second stage ends.

[0056] In the second stage of paper feeding operation shown in FIG. 5B, the control unit 11 activates the air direction switching solenoid 349, causing the leading edge fan 311 to create an upward airflow. This airflow functions to separate any sheets other than the topmost sheet 90a adsorbed to the suction belt 323 during the second stage. For example, if the next sheet 90b also floats up in addition to the sheet 90a and is also adsorbed to the suction belt 323, it is separated and dropped back into the stack of sheets. The first sheet 90a is transported downstream by the suction belt 323 and the transport unit 35. The second stage ends and the operation transitions to the next, first stage, for example, after a predetermined time has elapsed since the sheet detection sensor S2 detected the sheet 90a, or after the sheet detection sensor S2 no longer detects any sheets.

[0057] In the first stage of the feeding operation for the next sheet 90b shown in Fig. 5C, the same operation as Fig. 5A is performed again, and the subsequent feeding operations are repeated. Also, in Fig. 5C, the previous sheet 90a continues to be conveyed downstream by the conveying unit 35.

[0058] (If there is a companion) Next, reference will be made to Figures 6A to 6C, which correspond to Figures 5A to 5C, respectively.

[0059] Unlike Fig. 5A, Fig. 6A shows that as paper sheet 90a rises, the next paper sheet 90b also rises. Also, Fig. 6B shows that paper sheet 90a is separated and falls after the second stage of separation, but is misaligned with the paper stack. For example, this occurs when the airflow from each fan 311, 312 is inappropriate, or when the surface properties or condition of paper sheet 90 make it difficult to separate from the paper stack.

[0060] The first stage in FIG. 6C after FIG. 6B shows a state in which a sheet 90 is adsorbed to the suction belt 323 while a leading edge occurs due to the influence of FIG. 6B. In this embodiment, the degree of leading edge is evaluated using the leading edge amount X. While leading edge itself is not directly problematic, it is a useful indicator of a possible paper feed problem, and if it becomes too large, it can cause a paper feed problem. The leading edge amount X is the amount by which the next sheet 90b is adsorbed when the topmost sheet 90a is transported, and is the amount by which the next sheet 90b protrudes from the correct position at the end of the first stage. Specifically, as shown in FIG. 6C, it is the deviation of the leading edge position (xn) of the sheet 90 adsorbed to the suction belt 323 from the correct position (reference position x0) at the end of the first stage. Here, the reference position x0 is a predetermined position in the X direction. In the absence of leading edge, for example, it is the leading edge position of the first sheet 90 adsorbed to the suction belt 323 when a stack of sheets is set (refilled) in the paper feed unit 30. The amount of early feed is detected by a process (detection unit) for detecting the amount of early feed, which will be described later (FIG. 11).

[0061] (Flying volume and fan air volume) Next, we will explain the relationship between the air volume and the amount of lead-in of each fan 311, 312. Fig. 7 is a graph showing the relationship between the amount of lead-in and the air volume of the front fan 311. Fig. 8 is a graph showing the relationship between the amount of lead-in and the air volume of the side fan 312.

[0062] 7, it can be seen that the amount of lead-in movement decreases as the airflow rate of front end fan 311 increases. In other words, the greater the amount of lead-in movement, the more effective it is to suppress it by increasing the airflow rate of front end fan 311.

[0063] On the other hand, as shown in Figure 8, it can be seen that the larger the airflow volume of the side fan 312, the greater the amount of accompanying feed. In other words, the more effective it is to suppress the larger the amount of accompanying feed, the more effective it is to reduce the airflow volume of the side fan 312. As such, the airflow volume and accompanying feed amount tendencies differ between the leading-edge fan 311 and the side fan 312, and the inventors of the present application have found that simply changing the airflow volume uniformly, as in Patent Document 1 (JP 2020-70166 A), does not reduce the amount of accompanying feed, and therefore does not reduce paper feed failures.

[0064] (Paper feeding process) FIG. 9 is a flowchart showing the paper feeding process of the paper feeding device 10 in the first embodiment.

[0065] (Step S11) When control unit 11 receives a command to start execution of a print job, control unit 11 proceeds to step S12. For example, when image forming apparatus 50 receives a print command from a user via operation display unit 57, control unit 11 receives a command to start execution from control unit 51.

[0066] (Steps S12 and S13) Control unit 11 activates fans 311 and 312. At the same time, suction fan 321 is activated to start the paper feed operation. Here, the paper feed operation is started, and the topmost sheet 90 is adsorbed onto adsorption belt 323 (first stage). Once sheet 90 has been adsorbed onto adsorption belt 323 and the timing is right for the sheet to be fed, adsorption belt 323 begins to be driven, and conveyance of sheet 90 begins (second stage).

[0067] (Step S14) The control unit 11 detects the amount of early feed by the detection unit, which is a function realized by the timer function of the control unit 11 and the sheet detection sensor S2.

[0068] (Step S201) 10 is a subroutine flowchart showing the process of detecting the amount of early feed (step S14). The control unit 11 starts counting with a timer at the timing when the second stage is reached and the driving of the suction belt 323 is started.

[0069] (Step S202) The control unit 11 monitors the paper detection sensor S2, for example, at a 1 msec interval, and waits until it turns ON (paper present) (NO), and if it turns ON and detects the passage (arrival) of the leading edge of the paper 90 (YES), it proceeds to step S203.

[0070] (Step S203) The control unit 11 calculates the amount of early feed X from the elapsed time tx, which is the timer value at the time the passage is detected. Specifically, this calculation is performed using the elapsed time tx, the conveying speed v1, the reference position x0 in the x direction, and the position x2 of the sheet detection sensor S2. The moving distance Ln is calculated by multiplying the elapsed time tx by the conveying speed v1, and the amount of early feed X, which is the leading edge position of the sheet 90 relative to the reference position x0 at the start of the drive of the suction belt 323, i.e., the start of the second stage, is calculated from this and the difference in the distance between the reference x0 and the position x2 (sensor-distance Ls). For example, when the amount of early feed X = 0, which is the minimum (index 0), the elapsed time tx = Ls / v1. When the amount of early feed X = Ls (position x2), which is the maximum (index 100), the elapsed time tx = 0. This completes the process of FIG. 10, and the process returns to the process of FIG. 9 and executes the processes from step S15 onwards (END (RETURN)).

[0071] (Step S15) Here, the air volume f1 of the tip fan 311 and the air volume f2 of the side fan 312 are set based on the amount of lead-in airflow calculated in step S14 (detection unit). Fig. 12 is a subroutine flowchart showing the correction process for the fan air volumes (step S15). Fig. 13 is a correction table showing the relationship between the amount of lead-in airflow and the air volume.

[0072] (Step S301) Here, the control unit 11 sets the fan air volume using a correction table as shown in FIG. 13, which is stored in advance in the memory unit 12. This correction table classifies the amount of early feed into three levels: large, medium, and small. If the ideal amount of early feed is indexed at 0 and the maximum allowable amount is indexed at 100, the large, medium, and small levels correspond to the upper, middle, and lower levels obtained by dividing this into thirds. For example, the index 100 corresponds to the upper limit of the allowable amount of early feed. This upper limit is a value slightly smaller than the amount of early feed that would cause a paper jam, for example, 30 mm. This upper limit of 30 mm corresponds to the position of the paper detection sensor S2 (sensor distance Ls). Note that instead of the correction table, air volume correction may be performed using a relational expression that indicates the amount of early feed and the corrected air volume.

[0073] As shown in FIG. 13, in this embodiment, the airflow volume f1 of the leading edge fan 311 is increased from the standard value, and the airflow volume f2 of the side fan 322 is decreased from the standard value, in accordance with the relationship between FIGS. 7 and 8 discovered by the inventors of the present application. The standard airflow volume is set in a setting table stored in advance according to the paper type (basis weight). Furthermore, the airflow volume f2 of the side fan 322 has a predetermined lower limit set in advance, and is not set below this lower limit, because if the side fan 322 is unable to perform its floating function, there is a possibility that another paper feed problem will occur (see "Insufficient floating" in FIG. 8). This completes the process of FIG. 12, and the process returns to the process of FIG. 9, where step S16 and subsequent steps are executed (END (RETURN)).

[0074] (Step S16) The control unit 11 adjusts the airflow rates of the fans 311 and 312 to the set values ​​in step S15, and reflects the adjustments in the settings when feeding subsequent sheets of paper 90. For example, in a print job in which printing is performed on successive sheets of paper 90, the fan airflow rates f1 and f2 adjusted based on the amount of early feed X when feeding the previous sheet of paper 90 (the nth sheet) are applied when feeding the next sheet of paper 90 (the n+1th sheet).

[0075] (Step S17) If the print job has not ended (NO), the control unit 11 returns the process to step S13 and repeats the subsequent processes. On the other hand, if the print job has ended (YES), the process ends (END).

[0076] (Variation) Next, the fan air volume correction process in the modified example will be described with reference to Figures 14 and 15. Figure 14 is a subroutine flowchart showing the process of step S15, and Figure 15 is an example of a correction table showing the relationship between paper information, early feed amount, and correction amount (for the leading-edge fan). In the following modified example, air volume control is performed based on paper information in addition to the early feed amount.

[0077] (Step S321) The control unit 11 acquires paper information that is associated with the target paper feed unit 30 and stored in the storage unit 12. The paper information is acquired in advance by the acquisition unit (communication unit 13), and is, for example, the basis weight of the stored paper 90.

[0078] (Step S322) The control unit 11 determines the correction amounts (delta amounts) df1 and df2 for the airflow of the fans 311 and 312, respectively, using a correction table stored in the storage unit 12. In the correction table relating to the correction amount df1 of the leading-end fan 311 shown in FIG. 15, the correction amount increases as the basis weight increases. For example, when the basis weight is 64 g / m 2 If the amount of early airflow is indexed at 100 (for example, the maximum value of 30 mm), the correction amount df1 for tip fan 311 will be 45%. Similarly, a correction table is used to determine correction amount df2 for side fan 312. As shown in FIG. 15, the correction amount for tip fan 311 is written so that the greater the amount of early airflow, the greater the positive value (in the direction of increasing airflow), but in the correction table for side fan 312, the greater the amount of early airflow, the greater the absolute value of the correction amount (in the direction of decreasing airflow).

[0079] (Step S323) The control unit 11 sets the airflow rates of the respective fans using the correction amounts df1 and df2 determined in step S323 according to the following formula: Note that, as described above, df2 is set to a negative value. Airflow rate of tip fan 311: f1=fs1+df1 Airflow rate of side fan 312: f2=fs2+df2 Here, fs1 and fs2 are standard air volumes before correction, and are fixed values ​​set in advance according to the basis weight (the larger the basis weight, the larger the value). As described above, the air volumes of the tip fans 311 and 312 are variable by the PWM value, and the variable range is 0 to 100%. For example, for a basis weight of 64 g / m 2 If the standard air volume fs1 is 30% and the correction amount df1 determined in step S322 is 45%, the air volume after correction will be 75%, which is the sum of these. Note that instead of using a fixed value, the correction amount may be added to the air volume after the last adjustment. For example, if the air volume f1 of the tip fan 311 is n =f1 n-1 +df1(f1 n is the adjusted air volume, f1 n-1 indicates the air volume after the most recent adjustment).

[0080] (Step S324) If the airflow rate f2 of the side fan 312 set in step S323 is less than a predetermined lower limit, the control unit 11 corrects it to the lower limit. This lower limit is the lowest value that ensures the effectiveness of floating in the first stage, as described above. The lower limit may be different depending on the paper type (basis weight) (the higher the basis weight, the higher the lower limit). For example, if the airflow rate f2 set in step S323 is 5% and this is less than the lower limit of 10%, the control unit 11 corrects it to the lower limit of 10%.

[0081] As described above, the feeding device according to this embodiment includes a detection unit that detects the amount of lead-in feeding that the next sheet will be transported with when the uppermost sheet is transported by the suction transport unit, and a control unit. The control unit controls the air volume of the leading fan so that the larger the lead-in feeding amount detected by the detection unit, the larger the air volume of the leading fan. This reduces the amount of lead-in feeding, thereby enabling stable paper feeding. In this embodiment, the control unit also controls the air volumes of the leading fan and the side fan so that the larger the lead-in feeding amount detected by the detection unit, the larger the air volume of the leading fan and the smaller the air volume of the side fan. This allows for more stable paper feeding.

[0082] (Second embodiment) Next, a paper feeder 10 according to a second embodiment will be described with reference to FIG. 16. FIG. 16 is a flowchart showing the paper feed process of the paper feeder in the second embodiment. Configurations other than those described below are the same as those in the first embodiment and its modified examples shown in FIGS. 1 to 15, and therefore further description will be omitted. In the second embodiment described below, the timing of fan air volume control is limited to a predetermined period after fan startup or to only the second stage.

[0083] (Steps S41 to S43) These processes are the same as steps S11 to S13 in Fig. 9. In response to receiving a print job, image forming apparatus 50 starts the fan and starts the paper feeding operation.

[0084] (Step S44) The control unit 11 determines whether it is time to implement fan airflow control. While a print job is being executed, the fan airflow may be adjusted throughout the entire period, as in the first embodiment. However, excessive adjustment may result in deviation from the optimal value. Furthermore, after the print job starts and the stopped fan is started, the airflow from the fan may become unstable for a predetermined period, resulting in an unstable floating state of the paper 90. Therefore, only if the predetermined period is reached, fan airflow control is implemented according to the subsequent leading feed amount (YES), and processing proceeds to step S45. On the other hand, if the predetermined period is not reached, fan airflow control is not implemented (NO), and processing proceeds to step S50. Here, the predetermined period can be one of two types. The first is the period from when the fan starts to start (step S42) until the leading feed amount falls below a predetermined value. The predetermined value is, for example, 0 mm, or when the leading feed amount falls below 10, which is 1 / 10 of the maximum allowable value (100). The period of the predetermined period is the timing when the leading feed amount first falls below the predetermined value. The second is from the start of fan activation (step S42) until a predetermined number of sheets and / or a predetermined time has elapsed. The predetermined number of sheets is, for example, several tens of sheets, and the predetermined time is, for example, within one minute.

[0085] (Steps S45 and S46) Here, similar to steps S14 and S15 in FIG. 9, the amount of early feed is detected by the subroutine processing of FIG. 10 and FIG. 12 or FIG. 14, and the fan air volumes f1 and f2 of the tip fan 311 and the side fan 312, respectively, are set based on the detected amount of early feed.

[0086] (Step S47) The control unit 11 adjusts the air volume of the side fan 312 to the air volume f2 set in step S46. For example, the fan air volume f2 set based on the amount of early feeding X when the previous sheet 90 (the nth sheet) was fed is applied to the feeding of the current sheet 90 (the n+1th sheet) (both in the first and second stages).

[0087] (Step S48) Controller 11 sets the airflow rate of leading edge fan 311 to standard airflow rate fs1 during the first stage of feeding of paper 90 (n+1th sheet). This standard airflow rate fs1 is set in advance according to the basis weight, as described above. During this first stage, the airflow direction of leading edge fan 311, which is switched by switching mechanism 34, is downward (see FIG. 5A, etc.).

[0088] (Step S49) When the control unit 11 shifts to the second stage by adsorbing the sheet 90 (n+1th sheet) to the adsorption belt 323, the control unit 11 switches the direction of the airflow of the leading edge fan 311 upward by the switching mechanism 34 (see FIG. 5B, etc.). At the same time, the control unit 11 applies the fan airflow volume f1 of the leading edge fan 311, which was set in step S46 based on the amount of advance feed X when the previous sheet (nth sheet) was fed, to the feeding of the current sheet 90 (n+1th sheet) in the second stage.

[0089] (Step S50) 9, if the print job is not finished (NO), the control unit 11 returns the process to step S43 and repeats the subsequent processes. On the other hand, if the print job is finished (YES), the process ends (END).

[0090] In this way, in the second embodiment, the timing for controlling the fan air volume is set to only for a predetermined period after the fan is started, so that the air volume control can be performed only during an appropriate period. Also, by controlling the air volume of the leading edge fan 311 to increase according to the amount of lead feed only during the second stage of paper feeding, the air volume control can be performed appropriately, and ultimately, more stable paper feeding can be performed.

[0091] The configuration of the sheet feeding device 10 and the image forming system 1000 equipped with the same described above is a description of the main configuration in explaining the features of the above embodiment, but is not limited to the above configuration and can be variously modified within the scope of the claims. Furthermore, configurations equipped in general sheet feeding devices or image forming systems are not excluded.

[0092] In the above-described embodiments, sheet feeding device 10 is configured as a separate unit from image forming apparatus 50, but they may be configured as an integrated machine. For example, main body sheet feeding unit 55 may be an air-assisted sheet feeding unit similar to sheet feeding unit 30, and the sheet feeding process that controls the air volume of each embodiment may be applied to this sheet feeding unit.

[0093] In addition, while an example has been shown in which the air volume is adjusted when the next sheet (the n+1th sheet) is fed based on the amount of early feed X when the previous sheet 90 (the nth sheet) was fed, the present invention is not limited to this, and the air volume may be adjusted based on the average of the detection results for multiple sheets. Furthermore, while an example has been shown in which the sheet detection sensor S2 is used as the unit for detecting the amount of early feed, the present invention is not limited to this, and a camera or optical line sensor may be disposed near the sheet detection sensor S2 and used as the detection unit. The amount of early feed is detected by determining the leading edge position of the sheet 90 at the start of the second stage through image analysis of image data acquired by this camera or line center.

[0094] Furthermore, the means and methods for performing various processes in the sheet feeding device 10 and image forming system 1000 according to the above-described embodiment can be realized by either a dedicated hardware circuit or a programmed computer. The above-described programs may be provided by a computer-readable recording medium such as a USB memory or a DVD (Digital Versatile Disc)-ROM, or may be provided online via a network such as the Internet. In this case, the programs recorded on the computer-readable recording medium are typically transferred to and stored in a storage unit such as a hard disk. The above-described programs may also be provided as standalone application software or may be incorporated into the software of the device as a function of the device. [Explanation of symbols]

[0095] 1000 Image Forming System 10 Paper feeder 11 Control section 12 Storage section 30 Paper feed section 31 Air supply unit 311 Tip Fan 312 Side Fan 313, 314 Duct 32 Suction conveying section 321 Suction fan 322 Duct 323 Suction Belt 326 Drive motor 33 Paper storage section 331 Placement section 332 Tip restriction plate 333 Side Regulating Plate 334 Rear end regulation plate 339 Lifting motor 34 Switching mechanism 341 Shutter 349 Switching Solenoid 35 Conveying section

Claims

1. a stacking section for stacking a plurality of sheets of paper; an air supply unit including a leading end fan that generates an air flow from a leading end side of the paper in a paper feed direction of the paper stacked on the stacking unit toward the paper; a suction conveyance unit that uses the air supply unit to suction and convey the topmost sheet separated from the stack of sheets; a detection unit that detects an amount of accompanying transport of the next sheet when the uppermost sheet is transported by the suction transport unit; a control unit, a switching mechanism that switches the direction of the airflow from the tip fan between a downward direction toward the topmost sheet of the stack of sheets loaded on the stacking section and an upward direction toward the suction conveying section that is disposed above the stack of sheets loaded on the stacking section, The paper feeding operation includes a first stage in which the topmost paper sheet is floated from the stack of paper sheets loaded in the stacking section and adsorbed to the adsorption conveying section, and a second stage in which the paper sheet adsorbed to the adsorption conveying section is conveyed downstream after the first stage, The control unit In the first stage, the direction of the airflow is set to a downward direction by the switching mechanism, In the second stage, the switching mechanism sets the direction of the air flow upward, and the air volume of the tip fan is controlled so that the larger the amount of paper feed detected by the detection unit, the larger the air volume of the tip fan.

2. the air supply unit further includes a side fan that generates an air flow toward the paper from a side of the paper stacked in the stacking unit that is perpendicular to the paper feed direction, The sheet feeding device according to claim 1 , wherein the control unit further controls the air volume of the side fan so that the air volume of the side fan decreases as the amount of early feed detected by the detection unit increases.

3. A lower limit value of the air volume of the side fan is set in advance, The paper feeding device according to claim 2 , wherein the control unit controls the air volume of the side fan so that the air volume does not fall below the lower limit value.

4. When the paper sheets stacked in the stacking section are continuously fed one by one, the control section 4. The paper feeding device according to claim 1, wherein the air volume control is performed according to the amount of leading edge feed of the front edge fan during a period from when the leading edge fan is started until the amount of leading edge feed decreases to a predetermined amount or less.

5. When the paper sheets stacked in the stacking section are continuously fed one by one, the control section 5. The paper feeding device according to claim 1, wherein the air volume control is performed according to the amount of early feed after the front fan is started, until a predetermined number of sheets are fed or until a predetermined time has elapsed.

6. Further, an acquisition unit is provided for acquiring paper information relating to the paper stacked in the stacking unit, 6. The paper feeding device according to claim 1, wherein the control unit performs the air volume control using a correction table or a relational expression that indicates the relationship between the paper information, the early feed amount, and the fan air volume or correction amount, which is pre-stored in a memory unit.

7. 7. The paper feeding device according to claim 1, wherein the detection section detects, as the amount of early feed, a distance conveyed downstream in the paper feeding direction when the preceding paper is conveyed by the suction conveyance section.

8. the detection unit includes a paper detection sensor that detects the presence or absence of paper at a predetermined position on the transport path downstream of the suction transport unit, The paper feeding device according to claim 7, wherein the control unit calculates the amount of early feed based on the amount of transport from when the suction transport unit starts to drive until the paper reaches the predetermined position, or the time it takes to reach the predetermined position.

9. a paper feeder according to any one of claims 1 to 8; an image forming unit that forms an image on the paper fed from the paper feeding device; An image forming system comprising:

10. a control program for controlling a paper feeding device including: a loading section for loading a plurality of sheets of paper; an air supply section including a leading end fan that generates an air flow from the leading end side of the sheets of paper loaded on the loading section in a paper feed direction toward the sheets; a suction transport section that sucks up and transports the topmost sheet separated from the stack of stacked sheets by the air supply section; a detection section that detects an amount of accompanying feed by which the next sheet is transported when the topmost sheet is transported by the suction transport section; and a switching mechanism that switches the direction of the air flow from the leading end fan between a downward direction toward the topmost sheet of the stack of sheets loaded on the loading section and an upward direction toward the suction transport section that is positioned above the stack of sheets loaded on the loading section, A step (a) of detecting an amount of early feed by the detection unit; a first stage in a paper feeding process of floating up the topmost sheet from a stack of sheets stacked in the stacking section and suctioning the sheet to the suction conveying section, in which step (b) sets the direction of the air flow to a downward direction by the switching mechanism; a second stage in the paper feeding process of transporting the paper adsorbed to the adsorption transport section downstream after the first stage in the paper feeding process, in which the direction of the air flow is set upward by the switching mechanism and the tip fan is controlled so that the air volume from the tip fan increases as the amount of paper adsorption detected in step (a) increases; and

11. the air supply unit further includes a side fan that generates an air flow toward the paper from a side of the paper stacked in the stacking unit that is perpendicular to the paper feed direction, 11. The control program according to claim 10, wherein in the steps (b) and (c), the air volume of the side fan is also controlled in accordance with the detected amount of accompanying movement, and the air volume of the side fan is controlled so that the air volume of the side fan decreases as the amount of accompanying movement detected by the detection unit increases.

Images