JP2010202380A - Paper feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper separation device that reduces driving torque when paper sheets are separated corresponding to types of the paper sheets and transferring conditions. <P>SOLUTION: A paper separating and transferring part 100 separates and transfers a paper sheet S on the uppermost face in a bundle 400 of paper sheets S placed on a paper sheet setting base 500 using a feed roller 200 and a reverse roller 300 that are movable for separation and transfer. A micro displacement sensor 910 for detecting overlap of the paper sheets is provided on the reverse roller 300. The number of the paper sheets S between the rollers 200, 300 provided for paper sheet separation is detected. A pressure Pb of the reverse roller 300 is increased when none of the paper sheets S is present, and the pressure Pb is not adjusted when one of the paper sheets S is present. The pressure Pb of the reverse roller 300 is decreased when two or more of the paper sheets S are present. The same kind of adjustment can be performed depending on the type of the paper sheets S. Through such adjustment, the pressure applied on the paper sheets between the rollers 200, 300 is varied, so that a transferring torque load while the paper sheets are separated and transferred can be reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet separating apparatus having a friction separating roller system, a sheet feeding apparatus using the sheet separating apparatus, and an image forming apparatus using them.

  In general, a sheet separating apparatus having a feed roller that rotates in the paper feeding direction and a reverse roller that is in pressure contact with the feed roller and is given a torque in one direction in the opposite paper feeding direction passes a certain torque limiter on the reverse roller. In this way, a load is applied, thereby enabling stable sheet separation.

  However, if there are two or more sheets being conveyed between the conveyance feed roller and the separation reverse roller, a high load torque limiter is required in the reverse rotation direction of the reverse roller. When there is only one sheet, it is not necessary to load the reverse roller in the reverse direction, and an unnecessary torque is applied only in that case. Therefore, at present, in order to counter such high torque, it is necessary to always apply high torque in the feed roller forward rotation direction, and a large output (for example, applied current value) is required as a drive source.

  In other words, wasteful power had to be used even though it was not necessary.

  SUMMARY OF THE INVENTION The present invention is intended to solve the above-described conventional problems, and is a paper separation device that reduces the driving torque at the time of paper separation according to the paper type and transport conditions, a paper feeding device using the paper separation device, and an image using these. An object is to provide a forming apparatus.

  The sheet separating apparatus according to a first aspect of the present invention includes a feed roller that rotates in the sheet feeding direction, and a constant torque applied in a direction opposite to the sheet feeding direction by a torque limiter in pressure contact with the feed roller. A friction separating roller type paper separating device that separates the multi-feed paper that has passed between these rollers, and comprises a nip portion between the feed roller and the reverse roller. The feed roller and the reverse roller include a double feed detection unit that includes a paper separation unit and detects double feed of paper on the downstream side in the paper conveyance direction, and a reverse roller drive gear that drives the reverse roller in the drive axis direction. A reverse roller pressure adjusting means for adjusting the pressure between the reverse roller pressure adjusting means and the reverse roller pressure adjusting means according to a detection result of the double feed detecting means. Characterized in that it has a control means.

  According to a second aspect of the present invention, there is provided the sheet separating apparatus according to the first aspect, wherein the double feed detecting means is a micro displacement sensor that measures the displacement of the reverse roller.

  According to a third aspect of the present invention is the paper separating apparatus according to the first aspect, wherein the double feed detecting means is located across the paper transport path, and changes in physical quantities caused by the paper transport during the paper transport. It is a transmissive sensor comprising a pair of sensors to be detected.

  According to a fourth aspect of the invention, there is provided the sheet separating apparatus according to any one of the first to third aspects, wherein a plurality of sets of double feed detecting means including the sheet separating unit are provided downstream in the sheet conveying direction.

  A fifth aspect of the present invention is the paper separating apparatus according to any one of the first to fourth aspects, further comprising a motor for moving the reverse roller driving gear.

  According to a sixth aspect of the present invention, a paper feeding device includes the paper separating device according to any one of the first to fifth aspects.

  According to a seventh aspect of the present invention, an image forming apparatus includes the paper separating device according to any one of the first to fifth aspects.

  An image forming apparatus according to an eighth aspect includes the paper feeding device according to the sixth aspect.

  The sheet separating apparatus according to the present invention, the sheet feeding apparatus using the sheet separating apparatus, and the image forming apparatus using the sheet separating apparatus vary the pressure of the separation roller depending on the sheet type and the number of sheets, thereby reducing the conveyance torque load during sheet separation and sheet conveyance. Can be.

Example of overall configuration Paper separation and conveyance section Example of overall configuration Paper separation transport mechanism A micro displacement sensor for measuring paper thickness is placed on the reverse roller Ultrasonic sensor for double feed detection placed downstream of the paper transport section Micro displacement sensor and ultrasonic sensor are arranged Feed drive control flowchart when a micro displacement sensor is installed Feed drive control flowchart when a micro displacement sensor and an ultrasonic sensor are arranged 1 is a schematic configuration diagram of an entire image forming apparatus according to the present invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, modes for carrying out the present invention will be described with reference to embodiments shown in the drawings. The present invention is not limited to the illustrated image forming apparatus, and can be applied to various apparatuses that perform image formation.

  FIG. 8 shows an overall schematic configuration diagram of an image forming apparatus which is an object of the present invention. Reference numeral 1 in the figure denotes an image forming apparatus main body. The image forming apparatus main body 1 is configured by mounting an image reading device 2 thereon and placing it on a table-like sheet bank 3. An automatic document feeder 4 is mounted on the image reading device 2 so as to be freely opened and closed.

  The image forming apparatus main body 1 includes a drum-shaped photoconductor 10 as an image carrier. Around this photosensitive member 10, from the charging device 11 arranged on the left side in the figure, in the order of the rotation direction (counterclockwise) A, the developing device 12 on the lower side, the transfer device 13 on the right side, and the cleaning device 14 on the upper side. Is arranged. Among them, the transfer device 13 is configured by winding a transfer belt 17 between upper and lower rollers 15 and 16, and the transfer belt 17 is pressed against the peripheral surface of the photoconductor 10 at the transfer position B.

  In FIG. 8, a toner supply device 20 that supplies new toner to the developing device 12 is provided on the left side of the charging device 11 and the cleaning device 14. Further, the image forming apparatus main body 1 includes a sheet conveying device C that feeds a sheet such as a sheet or an OHP sheet from a supply position (to be described later) and conveys the sheet to the stack position via the transfer position B. The sheet conveying apparatus C includes a supply path R1, a manual feed path R2, and a sheet conveyance path R, which will be described later. The sheet conveying path R is provided in a substantially L shape that passes between the photosensitive member 10 and the transfer device 13 and extends from the bottom to the top in FIG.

  In the sheet conveyance path R, a registration roller 21 is provided at an upstream position of the photoconductor 10. A fixing device 22 is provided at a downstream position of the photoconductor 10. The fixing device 22 includes a pair of fixing rollers (fixing roller rotating bodies) 30 and 32. A fixing heater is provided inside one fixing roller 30, and a pressure spring, a pressure arm, and the like are provided around the other fixing roller 32. The other fixing roller 32 is pressed from the right side of one fixing roller 30 by the pressure spring 25 and the pressure arm 26. The fixing roller 30 is also provided with a thermistor and a thermostat.

  The fixing roller 30 is kept at a predetermined temperature by measuring the temperature of the fixing roller 30 with a thermistor and turning on or off the fixing heater with a thermostat.

  Further downstream of the fixing device 22, a discharge branch claw 34, a discharge roller 35, a first pressure roller 36, a second pressure roller 37, and a waist roller 38 are provided. In addition, as shown in FIG. 12, a discharge stack portion (discharge position) 39 for stacking sheets on which images have been formed is provided.

  The image forming apparatus main body 1 is provided with a switchback device 42 on the right side in the drawing. The switchback device 42 branches from the position of the discharge branch pawl 34 of the sheet conveyance path R and leads to the switchback position 44 including the pair of switchback rollers 43, and again from the switchback position 44, the sheet conveyance path. A sheet conveying apparatus D having a re-conveying path R4 leading to the R registration rollers 21 is provided. The sheet conveying apparatus D includes a plurality of sheet conveying rollers 66 (sheet conveying rotating body) for conveying the sheet.

  A laser writing device 47 is provided on the left side of the developing device 12 in the drawing. The laser writing device 47 includes a laser light source (not shown), a scanning rotary polygon mirror 48, a polygon motor 49, a scanning optical system 50 such as an fθ lens, and the like. The image reading device 2 is provided with a light source 53, a plurality of mirrors 54, an imaging optical lens 55, an image sensor 56 such as a CCD, and the like. A contact glass 57 is provided on the upper surface.

  The automatic document feeder 4 on the contact glass 57 is provided with a placement table (not shown) at the document placement position and a discharge table (not shown) at the discharge position. In addition, a sheet conveyance device having a document conveyance path (not shown) that conveys a sheet such as a document from a placement table to a discharge table via a reading position on the contact glass 57 of the image reading device 2 is provided. The sheet conveying apparatus includes a plurality of sheet conveying rollers (sheet conveying rotating bodies) (not illustrated) that convey a sheet such as a document.

  The sheet bank 3 is internally provided with a plurality of sheet cassettes 61 that are the supply positions of the sheets S (in the figure provided there are only two stages, but this is not limitative). Each sheet cassette 61 is provided with a corresponding call roller 62 (feed roller), supply roller 63 (feed roller), and separation roller 64 (feed roller). A supply path R1 leading to the sheet conveyance path R of the apparatus main body 100 is formed on the right side of the sheet cassette 61 provided in multiple stages. The supply path R1 includes several sheet transport rollers 66 (sheet transport rotating body) that transport sheets.

  The image forming apparatus main body 1 is provided with a manual feed unit 68 on the right side in the drawing. The manual feed unit 68 is provided with a manual feed path R2 that opens and closes a manual feed tray 67 (supply position) and guides a manual sheet set on the manual feed tray 67 to the sheet conveyance path R. Similarly, the manual feed tray 67 is provided with a calling roller 62 (feed roller), a supply roller 63 (feed roller), and a separation roller 64 (feed roller).

  When making a copy using this copying machine, a main switch (not shown) is turned on and a document is set on the automatic document feeder 4. Alternatively, the automatic document feeder 4 is opened, a document is set directly on the contact glass 57 of the image reading device 2, and the automatic document feeder 4 is closed and pressed.

  When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 4, the document is moved onto the contact glass 57 through the document conveyance path by the sheet conveyance roller, and then the image reading device 2 is moved. Drives, reads the contents of the document, and discharges it on the discharge table. On the other hand, when the document is set directly on the contact glass 57, the image reading apparatus 2 is immediately driven.

  When the image reading device 2 is driven, the image reading device 2 moves the light source 53 along the contact glass 57, reflects light from the light source 53 on the original surface on the contact glass 57, and reflects the reflected light to a plurality of light sources 53. The light is reflected by a mirror 54, passes through an imaging optical lens 55, is put in an image sensor 56, and the image content is read by the image sensor 56.

  At the same time, the photoconductor 10 is rotated by a photoconductor drive motor (not shown), and in the illustrated example, the surface is first uniformly charged by a charging device 11 using a charging roller, and then the image reading device 2 described above. The laser writing device 47 irradiates a laser beam in accordance with the content of the read document and writes it with the laser writing device 47 to form an electrostatic latent image on the surface of the photosensitive member 10. Visualize the electrostatic latent image.

  At the same time when the start switch is pressed, the sheet S is sent out from the corresponding sheet cassette 61 in the plurality of sheet cassettes 61 provided in multiple stages in the sheet bank 3 by the calling roller 62, and subsequently supplied by the supply roller 63 and the separation roller 64. Each sheet is separated and fed into the supply path R1 while being conveyed, conveyed by the sheet conveying roller 66 to the sheet conveying path R, abutted against the registration roller 21 and stopped. Then, the registration roller 21 is rotated in synchronization with the rotation of the image visualized on the photoreceptor 10 described above, and is sent to the right side of the photoreceptor 10.

  Alternatively, the manual feed tray 67 of the manual feed unit 68 is opened, the manual feed sheet set on the manual feed tray 67 is sent out by the calling roller 62, and is separated by the supply roller 63 and the separation roller 64 one by one and manually fed while being conveyed. The sheet is fed into the supply path R2, is transported by the sheet transport roller 66, is guided to the sheet transport path R, and is similarly fed by the registration roller 21 to the right side of the photoreceptor 10 in time with the rotation of the photoreceptor 10.

  Then, on the sheet S fed to the right side of the photoconductor 10, an image on the photoconductor 10 is transferred at a transfer position B by a transfer device 13 having a transfer belt 17 in the illustrated example to form an image. Residual toner on the photoconductor 10 after image transfer is removed and cleaned by a cleaning device 14, and a residual potential on the photoconductor 10 is removed by a neutralization device (not shown) to prepare for the next image formation starting from the charging device 11. .

  On the other hand, the sheet S after image transfer is conveyed by the transfer belt 17 and passed between the pair of fixing rollers 30 and 32 of the fixing device 22, and heat and pressure are applied thereto to fix the transferred image by the fixing device 22. . Thereafter, the sheet is seated by the discharge roller 35, the first pressure roller 36, the second pressure roller 37, and the waist roller 38, discharged onto the discharge stack portion 39, and stacked there.

  Note that the discharge branch claw 34 is switched when images are transferred to both sides of the sheet. Then, the sheet with the image transferred on the surface is put from the sheet transport path R to the reverse path R3, transported by the sheet transport roller 66, put into the switchback position 44, switched back at the switchback position 44, and then restarted. The sheet is reversed into the conveyance path R4, conveyed by the sheet conveyance roller 66, guided again to the sheet conveyance path R, and the image is transferred to the back surface of the sheet in the same manner as described above.

  FIG. 2 shows a sheet separating and conveying unit 100 that can be used in the above-described image forming apparatus. The figure shows a state in which the uppermost sheet S of the bundle 400 of sheets S placed on the sheet setting table 500 is separated and conveyed by a feed roller 200 and a reverse roller 300 that can be separated and conveyed.

  FIG. 3 shows a sheet separating / conveying unit mechanism in the sheet separating / conveying unit 100. The feed roller 200 is driven to rotate forward in the transport direction via the drive shaft 110 by the drive source 700, and the reverse roller 300 is driven via the drive shaft 120, the drive gear 130, the reverse roller drive gear 900, and the torque limiter 800 that controls the transmission torque. Thus, it is shown that they are arranged so as to rotate in the reverse direction to the transport direction.

  The torque limiter 800 is always fixed by meshing with the reverse roller 300, and the shaft side is also meshed with the spring pin of the drive shaft 150, so that the rotational force of the drive shaft is transmitted to the reverse roller 300 via the torque limiter. ing.

  The reverse roller drive gear 900 uses a motor 140 as a drive source through a pinion-rack connection so that a large moving stroke can be realized.

  FIG. 4 shows how many sheets S are present between the rollers 200 and 300 for separating paper by disposing a sensor, for example, a micro displacement sensor 910, on the reverse roller 300. An example of detection is shown. Control in this example will be described. First, the pressure Pb of the reverse roller 300 is increased when there is no sheet S, the pressure Pb is not adjusted when the sheet S is one, and the pressure of the reverse roller 300 when there are two or more sheets S. Control to weaken Pb. That is, the same control can be performed depending on the paper type of the paper S. By this control, the pressure applied to the paper between the rollers 200 and 300 can be varied, and the load on the transport torque during paper separation and paper transport can be reduced. Of course, such control is an example and does not mean that the control of the present invention is limited to this example. The control means may be controlled by providing a microcomputer or other known control device in the paper feeding device or the image forming apparatus, and illustration and description thereof will be omitted.

  FIG. 5 shows that two or more sheets are provided between the rollers 200 and 300 for the separation roller by disposing transmissive ultrasonic sensors 920 and 920 for detecting the overlap of sheets immediately after the sheet separation unit, for example. It is configured to detect whether or not S is present.

  Specifically, the pressure Pb of the reverse roller 3 is increased when there is no sheet S, the pressure Pb is not adjusted when the sheet S is one sheet, and the reverse roller 3 when the sheet S is two sheets or more. The control to weaken the pressure Pb is performed. By using the transmission type ultrasonic sensor 920, it is possible to detect when the sheet S is a single sheet or a plurality of sheets by discriminating the state of transmission of ultrasonic waves, thereby detecting double feeding. Compared to the case where light transmission detection is performed, it is possible to realize detection that is more advantageous for dirt such as paper dust.

  FIG. 6 shows a flowchart of the operation of the embodiment device when a micro displacement sensor or an ultrasonic sensor is used. Since the contents are as described above, the description is omitted.

  In FIG. 7, for example, a micro displacement sensor 910 for detecting overlap of sheets is disposed on the reverse roller 3, and a transmission type ultrasonic sensor 920 for detecting overlap of sheets is disposed immediately after the sheet separation unit. First, it is detected whether or not there is one or more sheets S between the separation rollers 200 and 300 by the micro displacement sensor 910, and then whether or not there are two or more sheets S is detected by the ultrasonic sensor 920. . The number of sheets between the separation rollers can be detected more accurately than when one sensor is used.

  FIG. 8 shows a flowchart when both the micro displacement sensor 910 and the ultrasonic sensor 920 are used. Since the contents are as described above, the description is omitted.

1: Image forming apparatus main body 2: Image reading apparatus 3: Sheet bank 4: Automatic document feeder 10: Photoreceptor 11: Charging apparatus 12: Developing apparatus 13: Transfer apparatus 14: Cleaning apparatus 15, 16: Roller 17: Transfer belt 20: Toner supply device 21: Registration roller 22: Motor 22: Fixing device 30, 32: Fixing roller (fixing roller rotating body)
28: thermistor 29: thermostat 34: discharge branch claw 35: discharge roller 36: first pressure roller 37: second pressure roller 38: waist roller 39: discharge stack portion (discharge position)
42: Switchback device 43: Switchback roller 44: Switchback position 47: Laser writing device 48: Rotating polygon mirror 49: Polygon motor 50: Scanning optical system 53 such as fθ lens 53: Light source 54: Mirror 55: For imaging Optical lens 56: Image sensor 57 such as CCD: Contact glass 61: Sheet cassette 62: Calling roller (feeding roller)
63: Supply roller (feed roller)
64: Separation roller (feeding roller)
66: Sheet transport roller (sheet transport rotating body)
67: Bypass tray (supply position)
68: Manual feed unit 100: Paper separation / conveyance unit 110, 120, 150: Drive shaft 130: Drive gear 140: Motor 200: Feed roller 300: Reverse roller 400: Paper bundle 500: Paper installation table 700: Drive source 800: Torque limiter 900: reverse roller driving gear 920: ultrasonic sensor 910: micro displacement sensor Pb: reverse roller pressure S: sheet C: sheet conveying device D: sheet conveying device R: sheet conveying route R1: supply route R2: manual feed Path R3: Inversion path R4: Re-transport path

JP 2002-053237 A Japanese Patent No. 3312950

Claims (8)

A feed roller that rotates in the paper feed direction;
A reverse roller that presses against the feed roller and is given a constant torque in a direction opposite to the paper feeding direction by a torque limiter;
A friction separating roller type paper separating device for separating paper that has been multi-fed by passing between these rollers,
A double feed detection means that includes a paper separation portion that includes a nip portion between the feed roller and the reverse roller, and detects double feed of paper on the downstream side in the paper transport direction;
Reverse roller pressure adjusting means for adjusting a pressure between the feed roller and the reverse roller by moving a reverse roller driving gear for driving the reverse roller in a driving axis direction;
A sheet separating apparatus comprising: a control unit configured to control the reverse roller pressure adjusting unit according to a detection result of the double feed detection unit. The sheet separating apparatus according to claim 1,
The double feed detection means is a micro displacement sensor that measures the displacement of the reverse roller.
A sheet separating apparatus characterized by the above. The sheet separating apparatus according to claim 1,
The multi-feed detection means is a transmission type sensor that is located across the sheet conveyance path and includes a pair of sensors that detect a change in physical quantity caused by the sheet conveyance during sheet conveyance.
A sheet separating apparatus characterized by the above. The paper separating apparatus according to any one of claims 1 to 3,
A plurality of sets of double feed detection means downstream of the sheet conveying direction including the sheet separating unit are installed.
A sheet separating apparatus characterized by the above. The sheet separating apparatus according to any one of claims 1 to 4,
Provided with a motor for moving the reverse roller drive gear,
A sheet separating apparatus characterized by the above. A paper feeding device comprising the paper separating device according to claim 1. An image forming apparatus comprising the sheet separating apparatus according to claim 1. An image forming apparatus comprising the paper feeding device according to claim 6.