JP4952564B2 - Paper feeding device and image forming apparatus - Google Patents

Description

  The present invention relates to a paper feeding device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, a printing machine, and a multifunction machine, and in particular, can reliably separate and feed paper such as coated paper one by one. The present invention relates to a paper feeding device.

  The image forming apparatus is provided with a paper feeding device that feeds one sheet at a time from a bundle of stacked sheets by a paper feeding roller or the like. In such a sheet feeding device, if a plurality of sheets are double fed, it may cause a paper jam. Further, if the conveying force is small, misfeeding is likely to occur. For this reason, a device has been devised that can reliably feed one by one. That is, misfeeds are prevented by reliably feeding out the uppermost sheet of the stacked sheets by increasing the coefficient of friction between the sheet feeding roller and the sheet. Further, in order to prevent two or more sheets from being sent out, only the uppermost sheet is sent out by pushing back the second and subsequent plates by rolling with a rolling roller, padding or separation claw. .

  This method is effective as long as only ordinary plain paper is used. However, recently, the use of copying machines and printers has been expanded, and various types of paper such as coated paper have been used. Among these sheets, the adhesion between the sheets when stacked is strong, and it may be difficult to reliably prevent double feeding with the above-described sheet feeding device.

  Therefore, a method is adopted in which a blower opening is provided in front of the feeding direction of the stacked sheets, and air is blown from the blower openings toward a plurality of upper sheets of the stacked sheets, and suction suction is performed. Air from the front is passed between the sheets to separate the sheets, and the separated uppermost sheet is conveyed while suctioning. In addition to the air from the front of the paper, there is also one that blows air from the side of the paper. With such a configuration, it is possible to separate and feed various types of paper sheets one by one.

  However, even if the sheets are separated one by one by blowing air, there is a problem that, depending on the sheet, if the blowing of air is stopped, the sheets come into close contact again. With respect to such a problem, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-96993), if the paper is not fed even after a predetermined waiting time has elapsed since the paper feeding operation was performed, the air blower By means of air blowing for a predetermined time, re-adhesion is prevented.

  Further, in Patent Document 2 (Japanese Patent Laid-Open No. 60-56739), the time from when the suction conveyance unit starts suction until the uppermost sheet is sucked is measured, and when this time is longer than the reference time, A method has been proposed in which the amount of air blown from the side is increased and, if it is short, the amount of air blown is reduced.

  Japanese Patent Application Laid-Open No. 5-270676 discloses a paper feeding device that changes the timing of suction by suction conveyance means in accordance with the size and thickness of a recording paper.

  Japanese Patent Laid-Open No. 6-40579 describes a paper feeding device that can change the distance between the suction conveyance means and the uppermost surface of the paper according to the thickness and size of the paper.

Patent Document 5 (Japanese Patent Application Laid-Open No. 2001-151363) discloses a paper feeding device that stops paper immediately before a nozzle that blows air from the front end side of the paper and reliably separates it by blowing air. Are listed.
JP 2005-96993 A JP 60-56739 A JP-A-5-270676 Japanese Patent Laid-Open No. 6-40579 JP 2001-151363 A

  The above Patent Documents 1 to 5 all relate to stabilization of the suction state of the paper, but there is no description about improvement of paper separation. That is, when there are a plurality of sheets adsorbed by the adsorbing and conveying means, the conditions for separating the sheets are uniform in the above-mentioned Patent Documents 1 to 5. Even with the same paper type, the separability changes due to changes in the environment and time, and there is a problem in that double feeding cannot be prevented unless it corresponds to each separability.

  SUMMARY An advantage of some aspects of the invention is to provide a paper feeding device that can feed paper in consideration of the ease of separation of paper, and an image forming apparatus including the paper feeding device. It is said.

In order to achieve the above object, a sheet feeding device according to the present invention blows air to a sheet feeding tray on which a sheet bundle composed of a plurality of sheets is stacked, and to a side end of the sheet bundle loaded on the sheet feeding tray. A ventilation unit, an adsorption general feeding unit that sucks and conveys the uppermost sheet of the sheet bundle loaded on the sheet feeding tray one by one by suction of air, and blocks air blowing from the blowing unit A shielding member; a suction sensor that detects that the paper has been sucked by the suction transport unit; a transport roller that receives the paper transported from the suction transport unit and sends it to the next process; A control unit that controls the control unit and the shielding member, and a separation ease detection unit that detects the ease of separation of the paper provided in the control unit, and the control unit is a detection result by the separation ease detection unit. Based on the air from the blower It is characterized by changing the time to stop the blowing of.

  A front air blowing unit that blows air from the front of the paper transport direction to the front end of the paper bundle transport direction may be provided.

  In order to achieve the above object, an image forming apparatus according to the present invention includes an image forming unit that forms a toner image on an image carrier, a transfer unit that transfers a toner image on the image carrier to paper, and a transfer unit. A paper feeding device that conveys the paper, and a fixing device that heats and fixes the paper on which the toner image is formed, and the paper feeding device is any one of the above paper feeding devices. It is characterized by.

  As described above, according to the present invention, the following effects can be obtained.

  In the present invention, the ease of separation can be measured for each sheet of paper. In the case of paper that is difficult to separate, the time from adsorbing to transporting is lengthened, and separation of the second and subsequent sheets when a plurality of sheets are adsorbed is ensured, thereby preventing double feeding. . Or since the time which shields the ventilation of the air from a ventilation part is delayed and separation of the paper after the 2nd sheet is ensured, double feeding can be prevented. In the case of a sheet that is easy to separate, the time from suction to conveyance can be shortened. Or the time which shields the ventilation of the air from a ventilation part can be shortened. Even with the same paper quality, it is possible to cope with changes in the degree of ease of separation depending on the environment and conditions of use. Further, since each sheet can be fed in an optimum time, high-speed feeding is possible.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the embodiments described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Image forming apparatus]
FIG. 1 is an overall configuration diagram of an image forming apparatus including an image forming apparatus main body A, an image reading apparatus SC, an automatic document feeder DF, and a large capacity sheet feeding apparatus LT.

  The image forming apparatus main body A shown in the figure includes an image forming unit including a photosensitive member 1 that is an image carrier, a charging unit 2, an exposure unit 3, a developing unit 4, a transfer unit 5, a cleaning unit 6, and the like, a fixing unit 7, and a sheet. And a transport unit.

  The paper transport unit includes a paper feed cassette 10, a first paper feed unit 11, a second paper feed unit 12, a paper discharge unit 14, a transport path switching unit 15, a circulation refeed unit 16, and a reverse paper discharge unit 17. Has been.

  The document d placed on the document table of the automatic document feeder DF is conveyed by the paper feed unit, and one or both images of the document d are exposed by the optical system of the image reading device SC and read by the image sensor CCD. . The analog signal photoelectrically converted by the image sensor CCD is subjected to analog processing, A / D conversion, shade ink correction, image compression processing, and the like in the image processing unit 20 and then sent to the exposure device 3.

  In the image forming unit, processes such as charging, exposure, development, transfer, separation, and cleaning are performed.

  In the image forming unit, the surface of the photoreceptor 1 is charged by the charging unit 2, an electrostatic latent image is formed by laser light irradiation from the exposure device 3, and the electrostatic latent image is visualized by the developing device 4, and toner Become a statue. Next, the paper P stored in the paper feed cassette 10 is conveyed from the first paper feed unit 11. The paper P is conveyed in synchronism with the toner image by the second paper feeding unit 12 composed of registration rollers. Thereafter, the paper P is fixed by the fixing device 7 after the toner image is transferred by the transfer unit 5.

  The paper P after fixing is discharged out of the apparatus by the paper discharge unit 14. On the other hand, the toner remaining on the photosensitive member 1 is removed by the cleaning unit 6. In the case of duplex copying, the paper P on which the image is formed on the first surface is sent to the circulation refeed unit 16 and reversed, and after the image is formed again on the second surface in the image forming unit, the paper discharge unit 14 is formed. Is discharged out of the apparatus. In the case of reverse paper discharge, the paper P branched from the normal paper discharge path is switched back and upside down in the reverse paper discharge unit 17 and then discharged out of the apparatus by the paper discharge unit 14.

  A large-capacity paper feeding device LT which is a paper feeding device of the present invention is connected to the image forming apparatus main body A. The paper feeding device LT includes a paper feeding device main body 30, a blower unit 40, a front blower unit 50, a suction conveyance unit 60, and the like, accommodates a large amount of paper P, and puts one sheet P on the image forming apparatus main body A. Feed them one by one.

  The sheet feeder main body 30 includes a sheet feed tray 31, a leading end regulating member 32, a trailing end regulating member 33, and a guide rail 34. The paper feed trays 31 are configured in three stages, and each paper feed tray 31 is configured to be drawable from the paper feed device LT by a guide rail 34. The maximum paper supply amount of the paper supply device LT is about 10300 sheets.

  2 is a perspective view showing a main part of the paper feeding device LT of the present invention, FIG. 3 is a front sectional view of the paper feeding device LT, FIG. 4 is a plan view thereof, and FIG.

  In these drawings, the stacked sheets P are placed on the sheet feeding tray 31 and accommodated so as to be lifted and lowered by a mechanism (not shown). The side restricting member 41 is movable in the paper width direction, and lightly presses on both sides of the paper P in accordance with the paper width of the stacked paper P to restrict both side positions of the paper P. The side regulating member 41 has a step at the top, the upstream surface 41a in the sheet P feeding direction is high, and the downstream surface 41b is low. Although not shown, a support member that supports the upper end of the side regulating member 41 is attached to the upstream surface 41a. The downstream surface 41b overlaps a suction conveyance unit 60, which will be described later, in the paper conveyance direction (arrow X direction in FIG. 2). When the paper feed tray 31 is pulled out in the direction of the arrow Y in FIG. 2 during paper feeding, the downstream surface 41 b can pass under the suction conveyance unit 60.

  The leading edge regulating member 32 regulates the leading edge position in the transport direction of the paper P. The rear end regulating member 33 is movable in the transport direction of the paper P and restricts the rear end position in the transport direction of the paper P.

  As shown in FIG. 3, the rear end regulating member 33 is provided with a height detection sensor PS3 for detecting the height of the uppermost sheet P.

  In order to maintain the height of the stack of sheets stacked on the sheet feed tray 31 at an optimum height for blowing air and blowing the paper P, a control unit described later performs height detection shown in FIG. Based on the detection result of the sensor PS3, a lifting motor (not shown) is driven to perform control to raise the paper feed tray 31.

  As shown in FIG. 3, a suction conveyance unit 60 is disposed in the vicinity of the leading end of the paper P in the feeding direction. The suction conveyance unit 60 includes a suction belt 63 that rotates by winding a large roller 61 connected to a drive source and two small rollers 62. The suction belt 63 has a large number of small-diameter through holes. A suction duct 64 is disposed inside the suction belt 63 and transports the paper P while sucking it through the suction belt 63.

  When the suction belt 63 rotates while sucking the paper P, the uppermost paper P in the paper bundle accommodated on the paper feed tray 31 advances in the direction of the arrow X shown in the figure and is sent to the image forming apparatus main body A. The

  The suction sensor PS1 disposed in the vicinity of the suction surface of the suction belt 63 detects that the uppermost surface of the paper P has been sucked by the suction belt 63.

  A paper feed sensor PS2 disposed in the vicinity of the suction belt 63 on the downstream side of the paper feed direction of the paper feed tray 31 detects the passage of the paper P to be fed. The paper P that has passed through the paper feed sensor PS2 reaches the transport roller 65, where it is nipped between the upper and lower transport rollers 65. Thereafter, the sheet is fed to the image forming unit by the conveyance roller 65 instead of the suction belt 63. When the transport roller 65 nips the paper P, the transport sensor PS4 detects the paper P.

  A front air blower 50 is fixed to the paper feeder main body 30 near the tip of the suction belt 63 on the downstream side of the paper feed tray 31 in the paper conveyance direction. The front blowing unit 50 is configured by an electric fan or the like. Note that the front blowing unit 50 may be attached to the sheet feeder main body 30 so as to blow air to the front end portion of the sheet bundle via a duct.

  The electric fan 51 of the front blowing unit 50 is attached with the blowing port 53 facing upward. The air blown upward is changed in direction by the guide plate 52, blown obliquely upward from the blower port 53, and blown to the vicinity of the suction belt 63 of the suction conveyance unit 60.

  Driving of the front blowing unit 50 is controlled according to the type of the paper P. In other words, OHP film, trace paper, coated paper with a smooth surface, paper with perforations and lines, etc., and paper with offset printing applied with dusting air. To ensure separation.

  As shown in FIGS. 2 and 5, air blowers 40 that blow air on the upper side of the paper P stacked in the paper feed tray 31 from the side perpendicular to the conveyance direction of the paper P are provided on both sides of the paper feed tray 31. Arranged. The air blowing unit 40 includes an electric fan 42 that blows air onto the upper portion of the paper P from the air outlets 44 on both sides orthogonal to the paper P withdrawal direction.

  The air blowing part 40 is disposed in the side part regulating member 41. The electric fan 42 is attached with the air outlet 44 facing upward. The air blown upward is changed in direction by 90 ° by the air guide passage 43 and blown out from the blower opening 44 in the horizontal direction. The air blowing port 44 is opened near the upper end of the side regulating member 41. The width of the air outlet 44 is substantially the same as the width of the air outlet of the air blower 40. A positional relationship is desirable such that the uppermost sheet P is located approximately at the center of the upper and lower ends of the air outlet 44. Since the air blowing part 40 is attached in the side part regulating member 41, even when the size of the paper P is changed, the air blowing part 40 can also be moved by moving the side part regulating member 41. In addition, although the ventilation part 40 and the ventilation port 44 are provided in the both sides of the paper P in this Example, only one side may be sufficient.

  When the air blowing unit 40 is driven, air is discharged from the air blowing port 44, and air is blown onto several sheets at the top of the stacked sheets P. Air is blown from one end of the paper P through the paper to the other end. As a result, the upper several sheets of the paper P are separated one by one. The suction conveyance unit 60 takes out only the uppermost paper P from the paper P thus separated and reliably sends it to the downstream side.

  As shown in FIGS. 2 and 3, the air inlet of the blower 40 is shielded by a shielding member and can be opened and closed. That is, the plate-shaped shutter that is a shielding member is pivotally supported by the shaft 46 and opened and closed by the solenoid SOL. The control unit controls the shutter 45 so that it can be freely opened and closed to switch between performing and not performing the air blowing by the air blowing unit 40.

FIG. 6 is a cross-sectional view illustrating a process of sucking and conveying a sheet by the air blowing unit 40 and the front air blowing unit 50.

  FIG. 6A shows a sheet adsorption process. By the first blower V1 blown up by the blower 40 (the white arrow shown in the figure), a small number of sheets P on the upper layer of the bundle of sheets stacked on the sheet feed tray 31 are lifted against the weight of the sheet and sucked. It is adsorbed by the intake air V3 (open arrow in the figure) due to the negative pressure of the belt 63. The second air blower V <b> 2 (the white arrow in the figure) blown up by the front blower 50 blows the vicinity of the front bottom of the suction belt 63.

  FIG. 6B shows a paper separation process. When the shutter 45 shields the air inlet of the air blower 40 and stops air blowing, the air blown only by the front air blower 50 passes between the uppermost sheet P1 and the lower sheet P2. The uppermost sheet P1 is adsorbed by the intake air V3 of the adsorbing and conveying unit 60, and is separated from the sheet P of the sheet bundle excluding the uppermost sheet P1. The sheet P2 below the separated uppermost sheet P1 descends in the direction of the arrow due to the weight of the sheet P2, and is accommodated on the sheet P.

  By repeating the blowing of the air blowing unit 40 in this way, the floating of several sheets P2 at the top of the sheet bundle spreads over almost the entire surface of the air blowing ports 44 and 53, and the gaps between the sheets become substantially the same interval. And air passes through this gap. As a result, the separation of the paper P1 is improved and the paper P1 is easily sent out. As a result, the problem that the floating of the sheet P1 becomes too large and damages the sheet, or a plurality of sheets are floated together and cannot be separated is solved.

  After the separation of the paper P1 from the paper P2, the driving unit (not shown) of the suction conveyance unit 60 starts driving, and the single sheet P1 sucked by the suction belt 63 is conveyed.

  FIG. 7 is a block diagram illustrating a configuration of control of the paper feeding device, FIG. 8 is a flowchart illustrating control of the paper feeding device, and FIG. 9 is a timing chart illustrating control of the paper feeding device. The sheet feeding method will be described below with reference to these drawings. However, the following paper feeding method is an example, and the present invention is not limited to this.

  When the start of paper feeding is instructed by the control means 70, the air blowing unit 40 and the front air blowing unit 50 start air blowing (# 101). The suction duct 64 starts suction almost simultaneously (# 103). The air from the air blowing unit 40 is blown onto several sheets on the sheet bundle and separated one by one, and the uppermost sheet P is adsorbed to the adsorption belt 63. Then, the suction sensor PS1 is turned on (# 105).

  When the suction sensor PS1 is turned ON, the uppermost sucked paper and the second and subsequent papers are separated by the air blowing from the front air blowing unit 50. After a predetermined time (time d shown in FIG. 9) elapses after the suction sensor PS1 is turned on (# 106), the suction belt 63 starts conveying the paper (# 107). When the paper P advances in the arrow X direction and the leading edge reaches the paper feed sensor PS2 (# 109), the paper feed sensor PS2 is turned on, the shielding member 45 is closed, and the air blowing from the blower 40 is stopped (# 111). ).

  The sheet P further advances, the leading edge reaches the conveyance sensor PS4, is detected by the conveyance sensor PS4, and is nipped by the conveyance roller 65 (# 113). Then, the suction belt 63 is stopped (# 115), and thereafter, the paper P is transported by the transport roller 65. When the suction belt 63 is stopped, the suction of the suction duct 64 is also stopped.

  When the paper P further advances and the trailing edge of the paper passes the paper feed sensor PS2, the paper feed sensor PS2 is turned off (# 117), and the process returns to # 101. Start spraying. Thereafter, the process is repeated until paper feeding is completed.

  The control means 70 is provided with a separation ease detection means 71. This separation ease detection means 71 measures the time (time a shown in FIG. 9) from when the paper feed sensor PS2 detects the passage of the trailing edge of the paper P until the next paper P is sucked. . Alternatively, the time from when the trailing edge of the paper P passes through the suction sensor PS1 and the suction sensor PS1 is turned off until the next paper P is sucked (time b shown in FIG. 9) is measured.

  The value of a or b is short when it is difficult to separate the uppermost first sheet P and the second and subsequent sheets P when a plurality of sheets are adsorbed. become longer. If separation of the suction belt 63 is started early when separation is difficult, the second and subsequent sheets may not be separated, and the possibility of double feeding increases. Therefore, the value of a or b is compared with a standard value set in advance, and if the value of a or b is larger than the standard value, the suction sensor PS1 detects the suction of the paper P and then the suction. The time required to start conveyance by the belt 63 (time c shown in FIG. 9) is lengthened. In this way, it is possible to adjust the start timing of the next sheet conveyance, and the conveyance after the second and subsequent sheets when a plurality of sheets are adsorbed can be reliably started. Can be prevented.

  Instead of adjusting the time of c, you may adjust the time which shields the ventilation of the air from the ventilation part 40. FIG. For example, as shown in # 110 of FIG. 8 and d of FIG. 9, the time for stopping the air blowing from the blower 40 is adjusted after the paper feed sensor PS2 detects the leading edge of the paper. It is good as well. When adjusting the time d, the time c can be a fixed time, but both the time c and d may be adjusted. In FIG. 9, the time d is measured from the time when the paper feed sensor PS2 detects the leading edge of the paper. However, the time d is measured after the suction sensor PS1 detects suction, or when the suction belt 63 starts conveying. You may measure from.

  In this way, by extending the time for blowing air from the side of the sheet, separation after the second sheet when a plurality of sheets are adsorbed can be ensured.

  Although the large-capacity sheet feeding apparatus LT connected to the image forming apparatus main body A has been described as the sheet feeding apparatus of the present invention, the present invention is also applicable to the sheet feeding cassette 10 disposed in the image forming apparatus main body A. .

1 is an overall configuration diagram of an image forming apparatus including an image forming apparatus main body, an image reading apparatus, an automatic document feeder, and a large capacity paper feeding apparatus. The perspective view which shows the principal part of the paper feeder of this invention. FIG. 3 is a front sectional view of the sheet feeding device. The top view of a paper feeder. The side view of a paper feeder. Sectional drawing which shows the adsorption | suction conveyance process of the paper by a ventilation part and a front ventilation part. FIG. 3 is a block diagram illustrating a control configuration of a sheet feeding device. 6 is a flowchart showing how to feed paper. 6 is a timing chart showing control of the paper feeding device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 30 Sheet feeder main body 31 Sheet feed tray 32 Front end regulating member 33 Rear end regulating member 40 Blower 41 Side regulating member 42 Electric fan 43 Air guide path 44 Blower port 45 Shield member (shutter)
46 Axis 50 Front blower part 51 Electric fan 52 Guide plate 53 Blower port 60 Adsorption / conveyance part 63 Adsorption belt 65 Conveyance roller A Image forming apparatus main body LT Paper supply device P, P1, P2 Paper PSl Adsorption sensor PS2 Paper supply sensor PS4 Conveyance sensor SOL Solenoid Vl 1st ventilation V2 2nd ventilation V3 Intake

Claims (3)

A paper feed tray for stacking a stack of paper sheets,
A blower that blows air to the side edges of the sheet bundle stacked on the sheet feed tray;
A suction general feeding unit that sucks and conveys the uppermost sheets of the bundle of sheets stacked on the sheet feeding tray one by one by air suction;
A shielding member that shields air blowing from the blowing section;
A suction sensor that detects that the paper has been sucked by the suction conveyance unit;
A transport roller that receives the paper transported from the suction transport unit and sends it to the next process;
A control unit for controlling the air blowing unit, the adsorption general feeding unit and the shielding member;
A separation ease detection means for detecting the ease of separation of the paper provided in the control unit;
And the control unit changes a time for blocking air blowing from the blowing unit based on a detection result by the separation ease detection unit. The paper feeding device according to claim 1, further comprising a front air blowing unit that blows air from a front side of the paper transport direction to a front end of the paper bundle in the transport direction. An image forming unit for forming a toner image on the image carrier;
A transfer unit for transferring a toner image on the image carrier to paper;
A paper feeding device for transporting the paper to the transfer unit;
A fixing device that heats and fixes the paper on which the toner image is formed;
An image forming apparatus characterized in that said feeder has a sheet feeding apparatus according to claim 1 or 2.

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