JP2010076871A - Image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device stably conveying a paper sheet from a paper feed tray even when a conveyance speed of the paper sheet is increased. <P>SOLUTION: The image forming device includes: a plurality of paper feed trays housing a plurality of paper sheets; a paper feed means having an air suction means to feed the paper sheets one by one from the paper feed trays; a conveyance means conveying the paper sheets fed from the paper feed means; an image forming means forming an image on each of the paper sheets conveyed from the conveyance means; and a control means. The control means feeds the paper sheets in series and one by one from the plurality of paper feed trays to sequentially convey the paper sheets to the image forming means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming system having a plurality of paper feed trays.

  An image forming system such as a copying machine, a facsimile machine, or a printer has a plurality of paper feeding units 50 for storing paper, and separates and feeds the papers stacked and stored on each paper feeding unit 50 one by one. Then, it is conveyed to an image forming unit of the image forming system to form an image.

  In general, as a method for separating and conveying sheets one by one, a sheet feeding device having a roller conveyance type sheet feeding means 50 is widely used. In the roller conveyance method, the surface is formed of an elastic body having a high coefficient of friction such as rubber, and the sheets are separated and conveyed one by one by the frictional force with the roller surface in contact with the sheet.

  On the other hand, in recent years, an electrophotographic image forming system has been used in the field of light printing such as POD (print on demand), and is required to be able to meet various needs regarding image quality and recording materials. . In particular, with respect to the recording material, gloss coated paper, high quality paper, follow-up paper, recycled paper, and the like may be used.

  In order to improve the glossiness of the surface of gloss coated paper, a resin or the like is applied to the surface, so that the smoothness of the surface is high. When such gloss coated paper is used, the roller conveyance type paper feeding device cannot obtain a necessary frictional force between the paper and the roller surface, and sufficient paper feeding performance cannot be ensured. In addition, when reprinted paper or recycled paper is used, the release force (dusting powder) adhering to the paper is reduced in the former, and paper powder is transferred to the roller surface and adheres to the latter. Therefore, there is a problem in that sufficient paper feeding performance cannot be secured stably over the long term.

As a method for dealing with such a problem, a paper feeding device having an air suction method (hereinafter also referred to as an air conveyance method) paper feeding device has been proposed (see Patent Document 1). The sheet feeding device conveys the uppermost sheet of the stack of sheets stacked and stored on the sheet feeding means 50 by suction with a conveying belt one by one. Adsorption of the paper onto the conveyor belt is performed by utilizing the pressure difference of the airflow generated by the rotational drive of the suction fan. Such a sheet feeding device has an advantage that it can cope with various recording materials due to its configuration.
JP 10-316262 A

  In the field of light printing, improvement in productivity (the number of images formed per unit time) is always required. In order to improve productivity, generally, the image forming speed and the paper transport speed are increased.

  By increasing the paper conveyance speed, the paper feed interval from the paper feed tray storing the paper is also shortened, which causes a problem that conveyance failure at the time of feeding is likely to occur.

  In the air conveyance type paper feeder, the uppermost paper of the paper feed tray on which the paper is stacked is attracted to the transport belt by the air suction force, so the position where the paper is attracted to the transport belt from the stacking position. Time (hereinafter referred to as adsorption stabilization time) is required. If you try to feed the paper by moving the conveyor belt before the adsorption stabilization time has passed, the feed force between the conveyor belt and the paper will be insufficient, causing a no-feed jam due to paper conveyance failure. There is a problem that it ends up.

  Even in a roller conveyance type paper feeder, in order to feed paper at a high speed, if the rotation speed of the roller is increased, slippage between the paper and the roller is likely to occur, and as a result, a feed-out no feed jam occurs. It becomes easy. In order to prevent the occurrence of the slip, it is conceivable to increase the frictional force with the paper by increasing the biasing pressure of the roller to the paper. However, in such a case, the frictional force between the uppermost sheet and the roller can be secured, but the frictional force between the uppermost sheet and the sheet below it also increases, so a plurality of sheets are sent out simultaneously. There is a problem that a so-called double feed jam easily occurs.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of stably transporting paper from a paper feed tray even when the paper transport speed is improved in view of the above problems.

1. A plurality of paper feed trays for storing a plurality of sheets of paper;
A paper feeding means comprising air suction means for feeding paper one by one from the paper feed tray;
Conveying means for conveying the sheet fed from the sheet feeding means;
Image forming means for forming an image on the paper conveyed by the conveying means;
Control means for controlling conveyance of the paper;
An image forming apparatus having
The image forming system according to claim 1, wherein the control unit sequentially feeds sheets one by one from the plurality of sheet feeding trays and continuously conveys the sheets to the image forming unit.

2. A plurality of paper feed trays for storing a plurality of sheets of paper;
A paper feed means that includes a paper roller and feeds paper one by one from the paper feed tray;
Conveying means for conveying the sheet fed from the sheet feeding means;
Image forming means for forming an image on the paper conveyed by the conveying means;
Control means for controlling conveyance of the paper;
An image forming apparatus having
The control means includes
A single-tray paper feed mode for continuously conveying paper to the image forming means by conveying paper continuously from one paper feed tray;
Sheets are sequentially sent out from the plurality of sheet feeding trays one by one, conveyed continuously to the image forming unit, and the sheet conveying speed of the sheet feeding unit is set when the single tray sheet feeding mode is executed. An image forming system capable of executing a multi-tray sheet feeding mode that is slower than a sheet conveying speed.

3. Having an input means for obtaining operator instruction information;
The control means selects a plurality of paper feed trays to be used from among the plurality of paper feed trays according to instruction information from the input means, and sequentially supplies sheets one by one from the selected plurality of paper feed trays. 3. The image forming system as described in 1 or 2 above, wherein the sheet is sent out and continuously conveyed to the image forming means.

4). Storage means for storing paper information settings including at least paper size, paper type, paper basis weight of paper stored in each of the plurality of paper feed trays;
When performing continuous image formation on paper based on a print job,
The control means selects a plurality of paper feed trays to be used from the plurality of paper feed trays based on the paper size and paper type set for the print job or the paper size and paper basis weight information. Done
3. The image forming system as described in 1 or 2 above, wherein the sheets are sent out one by one from the selected plurality of paper feed trays in order, and the sheets are continuously conveyed to the image forming unit.

  According to the present invention, even when the paper conveyance speed is improved, the paper can be stably conveyed from the paper feed tray by conveying the paper one by one from the plurality of paper feed trays in order. It is possible to provide an image forming apparatus capable of performing the above.

  Although the present invention will be described based on an embodiment, the present invention is not limited to the embodiment.

  FIG. 1 is an overall configuration diagram of an image forming system including an image forming apparatus A, a post-processing apparatus FS, and a large-capacity paper feeding apparatus PFU. The illustrated image forming apparatus A is called a tandem color image forming apparatus, and includes an image forming unit A1, a scanner unit 1, an operation display unit 2, and an automatic document feeder D.

  The image forming unit A1 forms an image by electrophotography, and includes an image writing unit 3, a plurality of sets of image creating units 4Y (yellow), 4M (magenta), 4C (cyan), 4K (black), and a belt shape. The intermediate transfer member 42, the paper feed tray 5a, the paper feed tray 5b, the paper feed means 50, the transport means 60, the fixing device 7, the paper discharge section 8, and the automatic duplex copy transport section 9.

  The transport unit 60 includes a plurality of transport roller pairs 6a to 6h, and rotates by driving a drive motor (not shown) to transport the paper S.

  In the specification of the present application, the constituent elements are collectively indicated by reference numerals with alphabetic subscripts omitted, and the individual constituent elements are indicated by Y, M, C, K, or a to j. It is indicated by a reference sign with a letter.

  An automatic document feeder D (ADF) is mounted on the upper part of the image forming apparatus A. A post-processing device FS is connected to the paper discharge unit 8 side on the left side of the image forming apparatus A in the figure.

  The document placed on the document table of the automatic document feeder D is conveyed in the direction of the arrow, and an image on one or both sides of the document is read by the optical system of the scanner unit 1 and read into the CCD image sensor 1A.

  The analog signal photoelectrically converted by the CCD image sensor 1A is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in the memory control unit, and then sent to the image writing unit 3.

  In the image writing unit 3, output light from the semiconductor laser is applied to the photosensitive drum 41 of the image creating unit 4 to form a latent image. In the image creating unit 4, processes such as charging, exposure, development, transfer, separation, and cleaning are performed.

  The sheet S conveyed from the sheet feeding tray 5 by the sheet feeding unit 50 is conveyed by the conveying roller pair 6 of the conveying unit 60. The pair of conveyance rollers 6d on the upstream side of the image forming unit A1 functions as a registration roller. The conveyance roller pair 6d can release the drive transmission of the drive motor by a clutch, and synchronizes with the image formation by the image forming unit A1 by controlling the conveyance timing of the paper S. The toner image is transferred to the sheet S conveyed by the conveying means 60 by the transfer means 43, and the toner image is fixed by the fixing device 7 on the downstream side thereof. Then, it is sent from the paper discharge unit 8 to the post-processing apparatus B.

  When forming images on both sides of the sheet S, after one side image formation is performed by the conveyance path switching gate, the sheet S is conveyed downward immediately after passing through the fixing device 7 and sent to the automatic two-sided copy paper feeding unit 9 to be front and back. After the reversal, the image creating unit 4 again performs the double-sided image processing, and then the paper is discharged from the paper discharge unit 8, and post-processing is performed in the post-processing device FS.

  The operation display unit 2 functions as an “input unit” and includes a touch panel in which a touch screen is placed on a liquid crystal (LCD) panel. A user (operator) can input print conditions and post-processing setting information in a post-processing apparatus described below by inputting or selecting various settings through the operation display unit 2.

[Large capacity feeder]
The large-capacity paper feeder PFU is provided in each of the paper feed trays 5c, 5d, and 5e, and each of the paper feed trays 5, and feeds the top sheet of the paper bundle in the paper feed tray 5 one by one. A paper means 50 is provided. A large number of sheets S in the sheet feeding tray 5 are continuously fed and sent to the image forming apparatus A.

[Post-processing device FS]
In the sheet post-processing device FS, from the upper side of the figure, an insertion sheet feeding means 40, stacking means 30, and stapling means 20 containing insertion sheets (used for front and back covers) are arranged in a substantially vertical direction. They are arranged in columns.

  An inlet conveyance unit 70 is disposed at the upper right of the sheet post-processing device FS in the figure. A movable paper discharge tray 81 for discharging and stacking printed paper is disposed on the left side of the paper post-processing device FS in the figure. The movable paper discharge tray 81 can accommodate up to about 3000 sheets (A4 size, B5 size) on which images are formed.

  The sheet feeding means 50 provided in each of the sheet feeding trays 5a to 5e can be interchanged between a roller conveyance type and an air conveyance type. In the present embodiment, the paper feed trays 5a and 5b of the main body use a roller transport type paper feed means 50, and the paper feed trays 5c, 5d and 5e of the large capacity paper feeder PFU are air transport systems. The sheet feeding means 50 is used.

  Hereinafter, the roller conveyance system and the air conveyance system paper feeding unit 50 will be described.

[Paper Feeding Unit 50]
FIG. 2 is a cross-sectional view of a sheet feeding means 50 of a roller conveyance system provided with a separating roller. The sheet feeding means 50 shown in the figure includes a separating roller 51 as a pickup means, and a conveying roller 521 and a double feed preventing roller (reverse roller) 522 for separating the sheets S fed by the separating roller 51 one by one. Pre-registration as a registering unit 52 (also serving as a first loop forming unit) and a first abutting unit that temporarily stops the leading edge of the sheet S separated by the separating unit 52 and resumes conveyance It has a roller 53.

  When the sheet S stacked on the elevating bottom plate 56 is raised by an elevating member that is moved up and down by a motor (not shown) and reaches the predetermined position where the upper surface of the sheet S comes into contact with the outer peripheral surface of the rolling roller 51, a sensor (not shown) The upper surface is detected, and the raising of the elevating bottom plate 56 is stopped.

  The roller 51 and the transport roller 521 start to rotate in response to the paper feed signal. The separating roller 51 brought into pressure contact with the upper surface of the sheet S with a predetermined pressure sends the sheet S to the nip position between the transport roller 521 and the double feed prevention roller 522 and then moves away from the sheet surface.

  The double feed prevention roller 522 is driven through a torque limiter (not shown) in the direction opposite to the conveyance direction of the paper S (CCW direction in the drawing), and is pressed against the conveyance roller 521 with a predetermined pressure by a spring (not shown).

  The double feed prevention roller 522 has a torque limiter that exceeds the limit torque when the sheet S does not exist at the nip position and directly contacts the conveyance roller 521 or when one sheet S is fed to the nip position. The sheet S slides and is driven to rotate (CW direction in the drawing) by the conveyance roller 521 to convey one sheet S.

  On the other hand, when two or more sheets S are sent to the separation unit 52 position, the limit torque overcomes the frictional force between the sheets and causes the double feed prevention roller 522 to reversely rotate (CCW direction in the drawing), thereby lowering the lower sheet. S is pushed back to prevent the feeding of a large number of sheets (also referred to as a double feed), and the uppermost sheet S of the sheet bundle is fed one by one.

  A paper presence / absence detection sensor PS1 (paper presence / absence detection means) that detects the presence / absence of paper is disposed on the elevating bottom plate 56, and detects that the paper on the elevating bottom plate 56 is out of paper.

  In the present embodiment, the rollers of the sheet feeding means 50 such as the separating roller 51, the conveying roller 521, and the pre-registration roller 53 shown in FIG. 2 can change the sheet conveying speed by changing the rotational speed of the drive motor. In contrast, in the “multiple tray paper feeding mode”, the conveyance speed of the paper S is made slower than the “single tray paper feeding mode” described later. In the “single tray paper feeding mode”, the transport speed of the paper S in the paper feeding means 50 is substantially the same as the transport speed in the downstream transport means 60, but in the “multiple tray paper feeding mode”, It is considerably slower than the conveying speed of the conveying means 60. A one-way clutch is disposed on the drive transmission path of each roller of the sheet feeding means 50. By arranging the one-way clutch, it is configured such that no trouble occurs even if the one-way clutch is pulled by the conveying roller pair 6 of the conveying means 60 on the downstream side.

  FIG. 3 is a cross-sectional view of an air conveyance type paper feed means 50 having an air suction means. The rotating conveyor belt 541 sucks the uppermost sheet of the sheet bundle in the sheet feeding tray 5 by airflow using a suction fan, thereby feeding the sheets one by one. In addition, what is common with FIG. 2 is replaced with description by attaching | subjecting the same code | symbol.

  The sheet feeding means 50 shown in FIG. 1 includes an air conveyance unit 54 that separates and conveys the picked up sheets S one by one, a conveyance roller 55 that conveys the sheet S sent by the air conveyance unit 54, and a pre-registration roller 53. Have

  The air conveyance unit 54 that functions as “air suction means” includes a conveyance belt 541, support rollers 542 a and 542 b that support and rotate the conveyance belt, a suction fan 545, and a suction unit 543 that includes a duct. A number of holes are opened in the transport belt 541, and the sheets S are sucked one by one by the air flow to the suction unit 543. The sucked paper is sent to the transport roller 55 by the transport belt rotating in the CCW direction shown in the drawing.

  In the air conveyance type paper feeding unit 50, when the next sheet S is sucked by the air transport unit 54 after the top sheet S is transported, the sheet S is transported from the loading position to the transport belt 541 that is the suction position. It must be moved by air suction.

  FIG. 4 schematically shows the relationship between the adhering force of the next sheet S in the elapsed time (hereinafter referred to as the adsorbing time for each sheet) after the uppermost sheet S is conveyed. The horizontal axis indicates the suction time for each sheet, and the vertical axis indicates the suction force. In the example shown in the figure, if the suction time is 300 ms or more, the suction force is stable. In addition, it can be seen that, in a short time of 300 ms or less, the shorter the time, the smaller the attractive force. The suction force affects the transport performance of the paper S. If the conveyance belt 541 is rotated in a state where the adsorption force is insufficient at the time when the adsorption time is short, the paper S cannot be sufficiently conveyed, and non-feed jam due to conveyance failure is likely to occur.

[Control block]
FIG. 5 is a block diagram of a control system of the image forming system according to the present embodiment. The image forming apparatus A includes a state management unit C100, a scanner unit C120, an ADF control unit C130, an operation control unit C140, and a printer unit C150.

  The state management unit C100 controls the entire image forming apparatus A and processes image data. The read processing unit C101, DRAM control IC C103, image control CPU C102, program memory C104, system memory C105, and nonvolatile memory C106 A write processing unit C108, a compression / decompression ICC 109, and an input / output interface C110. The state management unit C100 functions as a control unit.

  The read processing unit C101 performs various image processing such as scaling and gradation processing on the image data from the scanner unit C120.

  The image control CPU C102 performs synchronous control of the scanner control unit C122, the ADF control unit C130, the printer control unit C152, and the like.

  The DRAM control unit C103 performs image data writing / reading control.

  The program memory C104 is a ROM that stores control programs for the image forming apparatus A and the image forming system, and the system memory C105 is a work RAM.

  The nonvolatile memory C106 stores various parameters used for controlling each unit.

  C107 is an image memory for storing image data, and has a compression memory C107A.

  C108 is a writing control unit that controls an LD (laser diode) that is an exposure light source of the printer unit C150.

  C110 is an interface for communicating with an external device such as a PC (personal computer).

  The scanner unit C120 includes a CCDC 121 that reads an image and outputs an image signal, and a scanner control unit C122.

  The operation control unit C140 includes an LCD C141 that performs display, and a touch panel and other operation buttons C142.

  The printer unit C150 includes an LDC 151 that writes an image using an LD (laser diode), an image creation unit 4Y that forms an image by an electrophotographic process, a printer control unit C152 that controls each other unit, and a conveyance control unit C153.

  In the conveyance control unit C153, the operations of the paper feeding unit 50 and the conveyance unit 60 related to the conveyance of the sheet are executed, and the conveyance path is switched.

  The post-processing device FS has a post-processing control unit c200, and executes stapling processing and the like in the post-processing.

[Control flow]
FIG. 6 is an explanatory diagram of a control flow performed by the image forming system according to the present embodiment. In step S11, a print job is input. An example of a print job setting input procedure will be described with reference to FIGS.

  7 to 9 are detailed views of the display screen A4 in the operation display unit 2. FIG. The following example is an example in which the setting is performed by the operation display unit 2 provided in the image forming system. However, the present invention is not limited to this, and in the system in which the image forming system is network-connected to an external personal computer terminal, the personal computer You may make it connect from a terminal.

  FIG. 7 shows a basic screen of the operation display unit 2 for performing various displays and operations. In the figure, the user can make various settings for the paper feed tray used for printing by operating the buttons inside the paper setting field D0. In the example shown in the figure, the paper feed trays 1 to 5 displayed in the paper setting column D0 correspond to the paper feed trays 5a to 5e in FIG.

  It is possible to switch between “automatic selection” and “manual selection” of the paper feed tray by the paper setting button D1. The automatic selection here refers to the paper setting that is set in each paper feed tray 5 by the state management unit C100 that functions as a control unit based on “size information” or “size information and paper type information” of the output paper. The paper feed tray 5 to be used is determined in accordance with the above information.

  When “manual selection” is set, the user selects one or more paper feed trays 5 by operating a setting button corresponding to each paper feed tray 5 in the paper setting field D0. The example shown in FIG. 7 shows a state where the paper feed tray 3 (5c) and the paper feed tray 4 (5d) are selected in the manual selection.

  When setting the paper feed tray, the paper setting D1 button is pressed. When the paper setting D1 button is pressed, a display screen A4 for setting conditions for a plurality of paper feed trays is displayed as shown in FIG. For various setting changes, the function setting sub-screen pops up (not shown) by pressing the D16 button and D40 button from the D11 button shown in FIG. 8, and various buttons are selected on the sub-screen. By doing. The setting is completed by pressing the OK button D3 after the setting.

  The user can set “paper information” such as the paper size, paper type, paper basis weight, and the like of the paper stored in each paper feed tray 5 on the setting screen of FIG. It is stored in the nonvolatile memory C106 functioning as “means”.

  Selection of the paper feed tray 5 as a candidate for automatic selection can be switched by selecting each of the automatic selection buttons D15. The paper feed tray for which “Yes” is selected is a selection target for automatic selection. Further, when setting the priority order among the automatically selected paper feed trays 5, the display screen shown in FIG. 9 pops up by pressing the priority order D40 button.

  Also in the display screen A4 shown in FIG. 9, the user can alternately switch the presence or absence of a paper feed tray to be automatically selected by pressing an automatic selection D16 button corresponding to each paper feed tray 5. In the example shown in the figure, the paper feed trays 1, 3, 4, and 5 are selected as the paper feed trays to be automatically selected.

  When setting the priority order among the paper feeding units to be used preferentially, the user selects the paper feeding tray at D20, and then selects the paper feeding unit by pressing the up arrow button D21 or the down arrow button D22. The priority order of the paper feed tray can be raised or lowered. In the example shown in the figure, the paper feed tray 4 (PFU) has the highest priority, and is hereinafter referred to as the paper feed tray 3 (PFU) and the paper feed tray 5 (PFU), and the lowest is the paper feed tray 1 (PFU). Main body). The paper feed tray 2 is excluded from the priority setting target because the automatic selection setting is “none”.

  The setting information set by the above setting screen is stored in the nonvolatile memory C106. After these settings are made, a print job based on these settings is input by setting a document on the automatic document feeder D and pressing the copy button on the main body. Printing is started based on the print job.

  Returning to FIG. 6, the description of the flow will be continued. In step S11, a print job is input on the setting screen shown in FIGS. In the subsequent step S12, from the setting information of the print job, the state management unit C102 functioning as a control unit determines whether the setting of the paper feed tray is manual selection or automatic selection. If it is a manual selection setting, the flow after step S21 is executed based on the setting, for example, the setting to use the paper feed tray 3 and the paper feed tray 4 in the example shown in FIG.

  On the other hand, if the selection of the paper feed tray is set to automatic selection, the process proceeds to step S13. In step S13, it is determined whether the input print job setting information includes designation of the paper type or paper basis weight in addition to the paper size information. Examples of the paper type here include plain paper, coated paper, high-quality paper, book paper, rough paper, and the like.

  If the paper type is specified or the paper basis weight is specified (step S13: Yes), in step S14, the selected number n of paper feed trays in the “multiple tray paper feed mode” is determined according to the designated conditions. The procedure for determining the selection number n will be described later. In the subsequent step S15, n sheets are selected from the paper feed trays 5 having the paper type or paper basis weight that matches the designated condition.

  On the other hand, if neither the paper type nor the paper basis weight is specified (step S13: No), in step S16, the paper size setting has the highest priority among the same paper feed trays as the print job settings. The paper feed tray is selected as the first paper feed tray. The priority order here is set in advance on the setting screen of FIG.

  In step S17, as in step S14, the selection number n is determined according to the paper type and paper basis weight conditions of the first paper feed tray selected in step S16. In step S18, n sheets are selected from the sheet feeding trays having the same paper type and sheet basis weight as the first sheet feeding tray selected in step S16.

  In step S21, the sheets S are sent out one by one in order from a plurality of paper feed trays selected by manual selection or automatic selection from step S13. For example, in the case of using two paper feed trays, the paper feed tray 5c and the paper feed tray 5d, the first sheet is conveyed from the paper feed tray 5c and the second sheet is conveyed from the paper feed tray 5d. The sheets S are sent out alternately from the sheet feed tray. Then, the sheets S conveyed from the respective sheet feeding trays are merged in the downstream path, and are continuously conveyed to the image forming unit A1 by a conveying roller pair 6d functioning as a registration roller at a predetermined interval.

  In step S22, an image is formed on the conveyed paper S and the process ends.

  [Number of selection n]

Table 1 shows an example of a correspondence table between the paper type and the selected number n in the paper basis weight g / m ² . It is an example of the correspondence table in an air conveyance system. The selection number n requires a long adsorption stabilization time because it takes a long time to adsorb a heavy paper having a large paper basis weight or a rough paper having a low surface smoothness and a rough surface. The correspondence table of Table 1 determines the set value of the selection number n corresponding to the necessary adsorption stabilization time.

  In step S14 (or step S17) in FIG. 6 described above, the selection number n is determined by referring to the correspondence table according to the paper type and paper basis weight conditions of the paper feed tray 5 to be used. In Table 1, the selection number n is determined according to the combination of the paper type and the paper basis weight, but a correspondence table determined by either one may be provided separately.

[Multi-tray paper feed mode]
Next, in a plurality of paper feed trays 5 using the “air conveyance type” paper feeding unit 50 and the “roller conveyance type” paper feeding unit 50, the sheets are conveyed sequentially or alternately from the paper feeding tray 5. The effect in the case will be described.

  (1) The effect of the two paper feed trays using the “air transport system” paper feed means 50 will be described with reference to FIG. FIG. 10A is a diagram for explaining paper conveyance in the single tray paper feeding mode, and FIG. 10B is a diagram for explaining paper conveyance in the multiple tray paper feeding mode. In the “single tray sheet feeding mode”, the sheet is continuously conveyed from the one sheet feeding tray 5 to continuously convey the sheet to the image forming unit A1, and in the “multiple tray sheet feeding mode”, a plurality of sheets are conveyed. The sheets are fed out one by one from the sheet feeding tray 5 in order and conveyed together in the downstream conveyance path, and then conveyed continuously to the image forming unit A1.

  The example shown in FIG. 10 is an example of an image forming system capable of printing 120 pages in an A4 size (120 ppm) per minute. The sheet conveying speed in the image forming unit A1 is 540 mm / s, and a sheet having a feed length of 210 mm is conveyed at a cycle of 270 mm (sheet interval 60 mm).

  In the “single tray paper feeding mode” shown in FIG. 10A, the paper feeding period in the paper feeding means 50 is 500 ms (= 270/540), and the paper interval from the feeding of the previous paper to the feeding of the next paper. Is 111 ms (= 60/540). In this case, even if the suction time is maximum, only the paper interval 111 ms can be secured, and at 111 ms, the sufficient suction time cannot be secured as shown in FIG. 4, and the paper feed becomes unstable due to insufficient suction power. .

  In the example of the “multiple tray paper feed mode” shown in FIG. 10B, the paper feed tray 5c feeds odd-numbered papers p1, p3, and p5, and the paper feed tray 5d feeds even numbers p2, p4, and so on. The second sheet is being fed. Then, the sheets conveyed one by one alternately (in order) from the two sheet feeding trays 5 are conveyed at a predetermined interval by the conveying means 60, and therefore are continuously provided to the image forming unit A1. Thus, the sheet can be conveyed.

  In the example of FIG. 10B, since the two paper feed trays 5 are used, the paper feed period in the paper feed means 50 of each of the paper feed trays 5c and 5d is twice that of FIG. 10A. The sheet interval can be increased by the period of one sheet, so that it becomes 611 ms (= 111 + 500).

  In the present embodiment, since the sheets can be sent out one by one from the plurality of sheet feeding trays in order, and the sheets can be continuously conveyed to the image forming unit, the sheet interval in the air conveying type sheet feeding unit is increased. Therefore, the suction time can be extended, and as a result, the sheet can be stably conveyed from the sheet feeding tray.

  (2) The effect of the two paper feed trays using the “roller transport system” paper feed means 50 will be described. In the roller conveyance type paper feeding means 50, it is effective to reduce the paper feeding speed in order to feed the paper stably.

  The explanatory diagram shown in FIG. 10A can also be used in the “single tray paper feeding mode” of the roller conveyance method, and will be described using the explanatory diagram. In FIG. 10A, the sheet feeding speed V1 in the roller feeding type sheet feeding means 50 and the feeding speed v2 in the conveying means 60 are both 540 mm / s, which is the same as the sheet feeding speed 540 mm / s in the image forming unit A1. .

  On the other hand, in the “multi-tray paper feed mode”, the paper feed speed V1 can be significantly slowed down to about 270 mm / s, for example. This will be described below.

  For example, when two sheets of the sheet feeding tray 5a and the sheet feeding tray 5b shown in FIG. 1 are used and sheets are fed alternately (in order) from the two sheet feeding trays, both the sheet feeding trays 5a and 5b are fed. Each of the rollers such as the pre-registration roller 53 of the means 50 is slowed down to 270 mm / s by changing the rotational speed of the drive motor.

  Since the conveyance speed v2 of the conveyance means 60 including the conveyance roller pairs 6a and 6b on the downstream side is 540 mm / s, which is the same as the paper conveyance speed of the image forming unit A1, the sheet fed from the sheet feed tray 5a is After the leading edge is bitten by the conveyance roller pair 6a, the sheet is conveyed at a conveyance speed of 540 mm / s. At that time, the upstream rear end of the sheet is in a state of being engaged with each roller of the sheet feeding means 50. As described above, since the one-way clutch is arranged in the drive transmission path of each roller, the conveying means. It is possible to follow the change in the paper conveyance speed accompanying the conveyance of 60.

  Similarly, after the sheet fed from the sheet feeding tray 5b at a feeding speed of 270 mm / s is bitten by the pair of conveying rollers 6b, the sheet is conveyed at a conveying speed of 540 mm / s.

  In the present embodiment, the sheets can be continuously conveyed to the image forming unit by sequentially feeding and conveying sheets one by one from a plurality of sheet feeding trays. Since the conveyance speed can be made slower than the conveyance speed on the downstream side, it is possible to stably convey the paper from the paper feed tray.

1 is an overall configuration diagram of an image forming system including an image forming apparatus A, a post-processing apparatus FS, and a large-capacity paper feeding apparatus PFU. It is sectional drawing of the paper feed means 50 of a roller conveyance system. It is sectional drawing of the paper feeding means 50 of an air conveyance system. FIG. 6 schematically shows the relationship between the suction force of the next sheet S and the elapsed time after the uppermost sheet S is conveyed. 2 is a block diagram of a control system of the image forming system according to the present embodiment. FIG. It is explanatory drawing of the control flow which the image forming system in this embodiment performs. 6 is a detailed view of a display screen A4 in the operation display unit 2. FIG. 6 is a detailed view of a display screen A4 in the operation display unit 2. FIG. 6 is a detailed view of a display screen A4 in the operation display unit 2. FIG. FIG. 10A is a diagram for explaining paper conveyance in the single tray paper feeding mode, and FIG. 10B is a diagram for explaining paper conveyance in the multiple tray paper feeding mode.

Explanation of symbols

A image forming apparatus A1 image forming unit 2 operation display unit PFU large capacity sheet feeding device 5a, 5b, 5c, 5d, 5e sheet feeding tray 50 sheet feeding means 51 paper roller 54 air conveying unit 541 conveying belt 543 suction unit 545 suction fan 60 Conveying means C100 State management section

Claims (4)

A plurality of paper feed trays for storing a plurality of sheets of paper;
A paper feeding means comprising air suction means for feeding paper one by one from the paper feed tray;
Conveying means for conveying the sheet fed from the sheet feeding means;
Image forming means for forming an image on the paper conveyed by the conveying means;
Control means for controlling conveyance of the paper;
An image forming apparatus having
The image forming system according to claim 1, wherein the control unit sequentially feeds sheets one by one from the plurality of sheet feeding trays and continuously conveys the sheets to the image forming unit. A plurality of paper feed trays for storing a plurality of sheets of paper;
A paper feed means that includes a paper roller and feeds paper one by one from the paper feed tray;
Conveying means for conveying the sheet fed from the sheet feeding means;
Image forming means for forming an image on the paper conveyed by the conveying means;
Control means for controlling conveyance of the paper;
An image forming apparatus having
The control means includes
A single-tray paper feed mode for continuously conveying paper to the image forming means by conveying paper continuously from one paper feed tray;
Sheets are sequentially sent out from the plurality of sheet feeding trays one by one, conveyed continuously to the image forming unit, and the sheet conveying speed of the sheet feeding unit is set when the single tray sheet feeding mode is executed. An image forming system capable of executing a multi-tray sheet feeding mode that is slower than a sheet conveying speed. Having an input means for obtaining operator instruction information;
The control means selects a plurality of paper feed trays to be used from among the plurality of paper feed trays according to instruction information from the input means, and sequentially supplies sheets one by one from the selected plurality of paper feed trays. 3. The image forming system according to claim 1, wherein the sheet is fed out and continuously conveyed to the image forming unit. Storage means for storing paper information settings including at least paper size, paper type, paper basis weight of paper stored in each of the plurality of paper feed trays;
When performing continuous image formation on paper based on a print job,
The control means selects a plurality of paper feed trays to be used from the plurality of paper feed trays based on the paper size and paper type set for the print job or the paper size and paper basis weight information. Done
3. The image forming system according to claim 1, wherein sheets are sequentially fed out from the selected plurality of sheet feeding trays one by one, and the sheets are continuously conveyed to the image forming unit.

Images