JP4428262B2 - Paper feeding device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a sheet feeding device that feeds a plurality of recording sheets stored in a sheet feeding tray one by one, and an image forming apparatus including the sheet feeding device.

  In general, an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a printing machine performs image formation continuously by automatically feeding recording sheets (sheets) one by one to an image forming unit. Usually, a sheet feeding device is installed inside the apparatus main body.

  In a conventional image forming apparatus, a paper feeding device is arranged at the lower part of the main body of the image forming apparatus, an image forming unit is arranged at the upper part of the main body of the image forming apparatus, and from the paper feeding device at the lower part of the main body of the apparatus to the upper image forming unit. There is one that has a transport path to reach. In such an image forming apparatus, the recording sheets (paper sheets) are carried out one by one on the conveyance path and supplied to the image forming unit.

  In the paper feeding device provided in this image forming apparatus, the paper feeding tray is detachably mounted on the image forming apparatus main body, the paper feeding tray is pulled out from the image forming apparatus main body, and the front end of the paper feeding tray in the paper carry-out direction In the state where the front end of the sheet bundle as a recording sheet is brought into contact with the front wall for positioning standing on the sheet, the recording sheet is stacked and bundled in a state where the recording sheet is stacked, and is again fed. Is set in the main body of the image forming apparatus to be used.

  In such a sheet feeding device, the sheet-feeding side portion of the sheet, which is a recording sheet stored in a large number of sheets on the sheet loading plate mounted on the bottom surface of the sheet feeding tray set inside the image forming apparatus main body, is stored. With the lower surface lifted, set so that the paper feed roller provided on the apparatus main body side comes into rolling contact.

  In this paper feeding device, by rotating the paper feeding roller, the uppermost recording sheet is sent from the front end side of the paper feeding tray in the paper carry-out direction toward the pair of carrying rollers arranged at the lower entrance of the carrying path.

  On this conveyance path, a guide member having an inclined guide upper surface formed between the front wall for positioning at the front end of the paper feed direction of the paper feed tray and the pair of conveyance rollers is arranged. The leading end of the uppermost recording sheet that has been sent out is guided in sliding contact with the upper surface of the guide and is sandwiched between the nip portions of the pair of conveying rollers.

  The recording sheet pulled out by the conveying roller pair is guided by the resist introducing mylar so as to bend in the vertical direction and is nipped by the resist roller pair.

  The recording sheet pulled out on the conveyance path in this way is conveyed by rotating the registration roller pair, and the trailing end of the curved recording sheet is dropped when the trailing end of the recording sheet falls off the sheet feeding tray side. The portion collides with the guide upper surface of the guide member due to the elastic restoring force and attractive force of the recording sheet.

  This recording sheet instantaneously generates a collision sound when its rear end collides with the guide upper surface of the guide member. This collision sound is a shocking component that is very annoying for hearing and is generated every time a sheet of recording paper is conveyed. Therefore, it is strongly required to reduce or prevent the collision sound.

  Therefore, in the conventional paper feeding device, a buffering protrusion is installed on at least a part of the guide upper surface of the guide member, and the rear end portion of the recording sheet conveyed by the conveying roller pair falls off the paper feeding tray side and falls. Sometimes, the recording sheet is configured so as to hit the buffering projection, and the buffering projection is fixed in advance to the portion where the rear end portion of the recording sheet on the upper surface of the guide falls and generates noise, thereby bonding the recording sheet. It has been proposed that the contact portion between the rear end portion and the guide upper surface is linear or dot-like to reduce the collision noise caused by the collision of the recording sheet (see, for example, Patent Document 1).

  However, as described above, when the buffer protrusion is provided on the guide upper surface of the guide member, the surface shape of the guide upper surface is not uniform, and the surface properties (material and surface roughness) of the guide upper surface are different. As a result, the leading edge of the recording sheet cannot slide smoothly on the guide upper surface of the paper feed guide, and cannot be guided so as to be sandwiched between the nip portions of the pair of conveyance rollers, or is protruded from the upper surface of the guide. There is a possibility that the leading end of the recording sheet is caught by the buffering projection and bent.

For this reason, in such a paper feeding device, it is possible to smoothly carry out the recording sheet (paper) one by one on the conveyance path following the image forming unit and simultaneously carry out the recording sheet onto the conveyance path. It is difficult to reduce the collision sound generated when the rear end of the recording sheet collides with the upper surface of the guide during the operation.
JP 2004-155533 A

  In view of the above-described points, the present invention enables the recording sheet to be smoothly guided from the sheet feeding device and pulled out on the conveying path to be conveyed, and impact noise generated when the recording sheet is unloaded from the sheet feeding device. It is an object of the present invention to newly provide an inexpensive sheet feeding device with a simple configuration and an image forming apparatus including the same.

Sheet feeding apparatus according to claim 1 includes a paper feed tray for accommodating the recording sheet, a recording sheet delivery means out feed to the pressed region of the paper feed tray one by one the contained the recording sheet separation, the A sheet feeding guide member having a guide plane portion that guides the leading end portion of the recording sheet pulled out from the sheet feed tray to the press-contact region by a recording sheet sending means, and upstream of the guide plane portion in the conveyance direction The side end is extended to the outside of a circular area having a radius from the recording sheet introduction position to the uppermost recording paper tip position accommodated in the paper feed tray with the recording sheet introduction position in the press contact area as a center. At the same time, the guide plane portion is formed so as to be along a radiation direction centered on the recording sheet introduction position of the press contact region .

According to a second aspect of the present invention, in the paper feeding device according to the first aspect, the guide flat surface portion abuts on a plane when a rear end portion of the recording sheet held between the press contact regions is lowered. It is formed as follows.

According to a third aspect of the present invention, in the paper feeding device according to the first or second aspect, at least a part of the paper feeding guide member is formed integrally with the paper feeding tray, and the paper feeding guide member The united portion of the paper feed tray is a circular area having a radius from the recording sheet introduction position to the top end of the recording paper stored in the paper feed tray with the recording sheet introduction position in the press contact area as the center. It is located outside.

According to a fourth aspect of the present invention, in the paper feeding device according to any one of the first to third aspects, the paper feeding guide member is divided into two in a direction orthogonal to a recording paper transport direction, and the recording sheet It is arranged on both sides of the delivery means.

With the configuration described above, when the rear end of the recording sheet is carried out of the paper feed tray, the rear end side of the recording sheet rides on a plane portion (guide plane) on the upper surface of the paper feed guide member. Therefore, the rear end portion of the recording sheet being conveyed collides with the upper surface constituted by a plane passing through the pressure contact area line of the separation conveying roller of the sheet feeding guide member. It does not have a free end portion that protrudes from the surface, and the rear end of the recording sheet collides with a wider plane, so that the collision force per unit area applied to the recording sheet can be reduced. In addition, even if the recording sheet tries to continue to vibrate due to the collision, the recording sheet vibration is attenuated more quickly because the trailing edge of the recording sheet is constrained by contacting the upper surface of the paper feed guide member in a larger area, The impact sound generated by the recording sheet is greatly reduced.
At the same time, the paper feed guide member is formed so as to extend from the pressure contact area to the outside of a circular area having a radius from the position of the uppermost recording paper stored in the paper feed tray to widen the guide range of the paper feed guide member. Therefore, it is possible to satisfactorily guide the leading end of a recording sheet formed of various materials in various thicknesses, or a recording sheet with a bent wrinkle to be reused, and lead it to the press contact region.
Further, by dividing the paper feed guide member into two in the direction orthogonal to the recording paper conveyance direction, it is possible to reduce the collision noise generated by the recording sheet at both ends in the width direction of the recording sheet.

In addition, the guide plane portion is formed so as to be along the radiation direction centering on the recording sheet introduction position in the press contact region, so that the rear end portion of the recording sheet is planarly formed on the guide plane portion on the upper surface of the sheet feeding guide member. The impact force per unit area at the time of collision can be reduced, and the generated sound can be reduced by reducing the energy that vibrates the trailing edge of the recording sheet.
Further, when the rear end portion of the recording sheet collides with the guide plane portion on the upper surface of the sheet feeding guide member in a plane, the air interposed between the recording sheet and the sheet feeding guide member is prevented from coming into contact with each other. Since it functions as a cushion that acts as a hindrance, the speed at which the recording sheet and the paper feed guide member collide is reduced, and the trailing edge of the recording sheet slowly collides with the paper feed guide member, so that the generated sound is Can be reduced. In addition, when the rear end portion of the recording sheet collides with the flat portion on the upper surface of the paper feed guide member, the rear end portion of the recording sheet is entirely covered even if vibration occurs in the rear end portion of the recording sheet. Since it abuts on the stationary and large paper feed guide member, the vibration of the trailing edge of the recording sheet is damped and the vibration of the recording sheet is quickly attenuated, so that the generated sound can be quickly reduced.

An image forming apparatus according to a fifth aspect includes the paper feeding device according to any one of the first to fourth aspects.

  With the configuration described above, it is possible to reduce the noise of the image forming apparatus including the sheet feeding device.

In the paper feeding device and the image forming apparatus including the same according to the present invention,
The recording sheet unloaded from the sheet feeding device can be smoothly guided with a simple structure and stably pulled out and conveyed on the conveying path, and when the sheet is unloaded from the sheet feeding device, the trailing edge of the recording sheet hits the object. Since the impact noise can be reduced with a simple configuration, the sheet feeding device can be manufactured at low cost, and an image forming apparatus including the sheet feeding device can be provided at low cost.

  An image forming apparatus provided with a sheet feeding device according to an embodiment of the present invention will be described with reference to FIGS. As shown in the perspective view of FIG. 1 and the schematic configuration diagram of FIG. 2, the image forming apparatus (digital copying machine) main body 10 has an image scanner 14 disposed above a printer 12 and an automatic document feeder on top thereof. 16 is arranged. In the present specification, the term “paper feeder” is defined to include a film or other recording sheet other than paper.

  The image scanner 14 is provided with a platen glass 18 (shown in FIG. 2) on which an original is placed.

  Further, the automatic document feeder 16 is provided with a document feed tray 24 on which one or a plurality of documents 22 to be copied are stacked. The automatic document feeder 16 automatically conveys the document 22 placed on the document feed tray 24 so that it sequentially passes through the copy position on the platen glass 18 and is discharged onto the document discharge tray 26. Configured to perform image scanning operations. The automatic document feeder 16 is mounted so that it can be opened and closed by a hinge (not shown) so that the upper part of the platen glass 18 can be opened.

  In addition, a paper discharge tray 20 is installed on the upper portion of the printer 12 between the image scanner 14 disposed above.

  The image scanner 14 is provided with a user interface for a user to input a start of copying and an exposure optical system 28 for reading a document image. The output signal of the original image read by the exposure optical system 28 is converted into digital image data by a control unit (not shown) and temporarily stored, and the printer 12 as image data for forming a latent image at a predetermined timing. Are output to a ROS (latent image forming device) 30 disposed inside the.

  Inside the printer 12, recording sheets (paper sheets) are pulled out one by one from a paper feeding device arranged at the lower part of the apparatus main body, passed through a transfer unit, discharged through the fixing unit to the paper discharge tray 20. A conveyance path is configured.

  A photosensitive drum 32 that is driven to rotate is mounted on a transfer unit disposed inside the printer 12. The surface of the photoconductive drum 32 is uniformly charged by the charging roller 34, and then exposed and scanned by the laser beam 36 emitted from the ROS 30 described above to form an electrostatic latent image.

  The electrostatic latent image thus formed on the photosensitive drum 32 rotates with the photosensitive drum 32, reaches the position of the developing roller 38, and the electrostatic latent image is developed into a toner image by the developing roller 38. Further rotation reaches the position of the transfer roller 40.

  Since the transfer roller 40 is applied with a transfer bias while being pressed against the photosensitive drum 32 in the transfer region, the toner image on the photosensitive drum 32 is conveyed on the conveyance path by the transfer roller 40. Transferred onto the recording sheet (recording paper).

  The recording sheet onto which the toner image has been transferred in this manner is further conveyed on the conveyance path in a state where the toner image is not fixed, reaches the fixing unit (fixing area), and is held between the pair of fixing rollers 42. The image is fixed.

  The recording sheet on which the fixing toner image is formed is further conveyed on the conveyance path, and is discharged from the paper discharge port 44 onto the paper discharge tray 20 and stocked.

  The sheet feeding device provided in the image forming apparatus (digital copying machine) main body 10 configured as described above is a recording sheet for feeding recording sheets one by one from a sheet feeding tray 46 and a bundle of recording sheets accommodated in the sheet feeding tray. Delivery means.

  As shown in FIGS. 1 and 2, the paper feed tray 46 has a paper storage case portion configured in a box shape for storing a large number of stacked recording sheets. A large number of sheets are stacked in this paper storage case portion with a positioning front wall standing on the front end of the paper feed tray in the paper carry-out direction and contacting the front end in the transport direction of a bundle of paper sheets as recording sheets. The recording sheets that are bundled are stored.

  The paper feed tray 46 is mounted in a tray accommodating space inside the image forming apparatus main body 10 so that it can be put in and out like a drawer from a paper feed tray insertion port formed on the front surface of the image forming apparatus main body 10.

  As shown in FIGS. 2 and 4, in the tray housing space of the image forming apparatus main body 10, the paper feed tray 46 is movably supported in order to insert or remove the paper feed tray 46 from the paper feed tray insertion port. A rail 48 is installed. Further, guided rails 50 are installed on both the left and right sides of the paper feed tray 46, and the guided rails 50 are mounted so as to be movable on the rails 48.

  A paper placement plate 52 is mounted on the bottom of the case-like portion for storing paper in the paper feed tray 46, and the recording sheet 54 is stacked on the upper surface of the paper placement plate 52. The paper placement plate 52 is configured to be rotatable about a rotation shaft 56 (shown in FIG. 2), and is rotated by a motor (not shown) to lift the paper placement plate 52 during paper feeding. The upper surface of the recording sheet 54 is held at a position where it contacts the pickup roller 58.

  That is, when the sheet loading plate 52 is not used, the pickup roller 58 is held at a horizontal position where the pickup roller 58 is lowered so as to be separated from the upper surface of the recording sheet 54. The pickup roller 58 is configured to move to the position shown in FIG.

  A pickup roller 58 serving as a recording sheet feeding unit is disposed at the upper position of the sheet feeding tray 46 on the sheet feeding side, and a feed roller 60 is disposed on the upper left side (downstream in the conveying direction) of the sheet feeding tray 46. A separation conveyance roller 64 composed of a retard roller 62 installed so as to be in rolling contact is disposed.

  These pickup roller 58 and separation conveyance roller 64 are configured to be shorter than the lateral width of the recording sheet 54. As a result, the area in contact with the recording sheet 54 can be reduced, the pressure per unit area can be increased, and the recording sheet 54 can be reliably picked up, separated and transported. Further, the pickup roller 58 and the separation conveyance roller 64 are arranged in the vicinity of the center in the direction (width direction) orthogonal to the conveyance direction of the recording sheet 54 in the conveyance path, causing a skew in which the recording sheet 54 is sent obliquely. And the recording sheets 54 of various sizes can be conveyed.

  The separation conveyance roller 64 described above is driven to rotate in the reverse direction to the feed roller 60 via a torque limiter, and there is no recording sheet 54 in the pressure contact area with the feed roller 60 or one recording sheet 54 exists. In this case, it is driven by the feed roller 60, and when a plurality of recording sheets 54 are conveyed to the pressure contact area, a reverse rotation type retard roller is used that rotates in the opposite direction to the feed roller 60 to handle the fed recording sheet 54. In addition to the above-mentioned means, as a retard member constituting the separating and conveying roller 64, the retard roller is used as a retard member that presses against the feed roller 60 and separates the sheets fed by the frictional force of the surface. A driven roller type retard roller is used to handle the paper that is driven and double-fed by the load resistance provided on the rotating shaft. There means may be constructed using various types of the retard means and the like.

  The pickup roller 58, the feed roller 60, and the retard roller 62 are configured to be longer than the length of the recording sheet 54 in the lateral width direction (direction intersecting the paper conveyance direction), and the recording sheet 54 is disposed in the entire lateral width direction of the recording sheet 54. The recording sheet 54 may be configured to be shorter than the length in the horizontal width direction, and may be configured to be in contact with the recording sheet 54 at a part of the recording paper in the horizontal width direction.

  Between the pickup roller 58 and the separation / conveying roller 64, two paper feed guide members 66 and 68 for guiding the leading edge of the recording sheet 54 to the nip portion of the separation / conveying roller 64 are arranged.

  Each of the paper feed guide members 66 and 68 is formed of, for example, a plastic plate having a thickness of 4 mm (may be formed of a metal plate). The paper feed guide members 66 and 68 can be made of any material such as paper, rubber, plastic, metal, etc., but various types of recording sheets 54 are stable in the pressure contact area of the separation conveyance roller 64. Therefore, it is desirable to use a material such as plastic or metal having sufficient mechanical strength and bending rigidity.

  The paper feed guide members 66 and 68 are divided into two with respect to the direction intersecting with the conveyance direction (recording paper conveyance direction) of the recording sheet 54 and are arranged with the retard roller 62 interposed therebetween. The paper feed guide member 66 on the near side in the direction in which the paper feed tray 46 is pulled out is formed integrally with the front wall of the paper feed tray 46 as shown in FIG. That is, one paper feed guide member 66 is disposed on the side where the paper feed tray 46 is pulled out to the outside of the pickup roller 58 and the separation transport roller 64, and is integrally formed on one side of the paper feed tray 46. To do.

  Further, as shown in FIG. 5, the paper feed guide member 68 on the back side in the direction of pulling out the paper feed tray 46 is configured independently. That is, the other paper feed guide member 68 is disposed on the opposite side of the pickup roller 58 and the separation transport roller 64 from the direction in which the paper feed tray 46 is pulled out to the outside, and is fixed in the image forming apparatus main body 10 (not shown). Adhere to the member.

  With such a configuration, the paper feed guide members 66 and 68 are prevented from interfering with the retard roller 62 during the operation of attaching and detaching the paper feed tray 46 without causing the paper feed guide members 66 and 68 to be at the leading edge of the recording sheet 54. Can be guided to the nip region of the separation conveying roller 64 more stably.

  Further, by forming the paper transport downstream end of one paper feed guide member 66 that is disposed on the front side of the retard roller 62 in the paper feed tray removal direction and formed integrally with the paper feed tray 46, The leading edge of the recording sheet 54 can be guided more stably to the pressure contact area of the nip portion of the separation conveyance roller 64.

  These sheet feed guide members 66 and 68 are transported in a plane portion for guiding the leading end portion of the recording sheet 54 that hits the upper surface thereof to be nipped between the feed roller 60 and the retard roller 62 in the separation transport roller 64. The upstream end in the direction (feed tray 46 side) is located on the feed tray 46 around the upstream end position in the conveyance direction of the nip (recording sheet 54 introduction position) between the feed roller 60 and the retard roller 62. It is configured to extend 1 mm outside (upstream in the conveying direction) from a circular area with a radius r having a distance to the leading end position of the uppermost recording sheet 54 accommodated (the leading end position of the uppermost recording sheet 54). When the rear end of the recording sheet 54 is carried out from the paper feed tray 46, the rear end side of the recording sheet 54 is a flat portion on the upper surface of the paper feed guide members 66 and 68 (guide plane). Configured to ride in.

  In other words, when the trailing edge of the recording sheet 54 is carried out from the sheet feeding tray 46, the trailing edge of the recording sheet 54 protrudes from the ends of the feeding guide members 66 and 68. Configure to not.

  In particular, one paper feed guide member 66 formed integrally with the paper feed tray 46 can be configured on the upper surface of the guide of the paper feed guide member 66 including the united portion of the paper feed guide member 66 and the paper feed tray 46. The leading end position of the uppermost recording sheet 54 accommodated in the paper feed tray 46 from the center in the conveyance direction upstream end (recording sheet 54 introduction position) in the pressure contact area of the nip portion of the separation conveying roller 64. It is easy to configure so as to be located outside a circular area having a radius r up to the top recording sheet 54 tip position).

  In the paper feed guide members 66 and 68 configured in this way, the entire guide plane for the recording sheet 54 is formed between the feed roller 60 and the retard roller 62 as shown by a three-dot chain line 68A in FIG. You may comprise by the plane which passes a part.

  In the case where the paper feed guide members 66 and 68 are configured in this way, the rear end portion of the recording sheet 54 being conveyed deviates from the upper end surface of the bundle of recording sheets 54 accommodated in the paper feed tray 46, and is first. The abutting portion is a guide plane of the paper feed guide members 66 and 68 configured by a plane passing through the pressure contact area line of the separation conveyance roller 64 on the guide plane in which the recording sheet 54 is in sliding contact. Note that only a predetermined portion of the paper feed guide members 66 and 68 with which the rear end of the recording sheet 54 comes into contact may be formed on a plane passing through the pressure contact area line of the separation conveyance roller 64, or the paper feed guide member. You may comprise the whole upper surface of 66,68 by this plane.

  Further, the upper planes of the paper feed guide members 66 and 68 may be configured as smooth planes or curved surfaces in order to smoothly guide the leading edge of the recording sheet 54 to the pressure contact area of the nip portion of the separation conveyance roller 64. Further, the sheet feeding guide members 66 and 68 may be configured such that a plate-shaped member is inclined and a bulk member having an inclined surface may be disposed.

  With the configuration described above, the rear end portion of the recording sheet 54 being conveyed collides with the upper surface formed by a plane passing through the pressure contact area line of the separation conveying roller 64 of the sheet feeding guide members 66 and 68. Therefore, the rear end of the recording sheet 54 does not have a free end portion that protrudes from the paper feed guide members 66 and 68, and the rear end of the recording sheet 54 collides with a wider plane. It is possible to reduce the collision force per unit area applied to the recording sheet 54. Further, even if the recording sheet 54 continues to vibrate due to the collision, the paper feed guide member 66 has a wider area at the rear end of the recording sheet 54. 68, the vibration of the recording sheet 54 is attenuated faster and the impact sound generated by the recording sheet 54 is greatly reduced.

  Also, as shown in FIGS. 4 to 6, the paper feed guide members 66 and 68 are fed from the upstream end in the transport direction (the paper feed tray 46 side) at the guide plane portion for the recording sheet 54 that hits the upper surface thereof. Radiation direction (radial direction) centering on the upstream end position in the conveying direction of the nip portion between the feed roller 60 and the retard roller 62, the guide plane portion corresponding to the range immediately before the nip portion between the roller 60 and the retard roller 62 ), When the rear end of the recording sheet 54 is unloaded from the paper feed tray 46, the rear end portion of the recording sheet 54 hits the flat portion of the upper surface of the paper feed guide members 66 and 68 in a plane. Make contact.

  With this configuration, the impact force per unit area when the rear end portion of the recording sheet 54 collides with the planar portion of the upper surface of the paper feed guide members 66 and 68 is reduced, and the recording sheet 54 The sound generated by reducing the energy for vibrating the rear end portion can be reduced.

  Further, when the rear end portion of the recording sheet 54 collides with the planar portion of the upper surface of the paper feed guide members 66 and 68 in a plane, the air interposed between the recording sheet 54 and the paper feed guide members 66 and 68 is increased. Since it functions as a cushion that works to prevent the two from coming into contact with each other, the speed at which the recording sheet 54 and the paper feed guide members 66 and 68 collide is reduced, and the rear end portion of the recording sheet 54 is slowly fed into the paper feed guide. The generated sound can be reduced by colliding with the members 66 and 68.

  Further, when the rear end portion of the recording sheet 54 collides with the planar portion of the upper surface of the paper feed guide members 66 and 68 in a plan view, even if vibration occurs in the rear end portion of the recording sheet 54, Since the end portion is in contact with the sheet feeding guide members 66 and 68 which have a large mass and are immovable on the entire surface, the vibration of the rear end portion of the recording sheet 54 is damped, and the vibration of the recording sheet 54 is quickly attenuated. Sound can be reduced quickly.

  The retard roller 62 constituting the recording sheet feeding means is pressed against the feed roller 60 by a spring (not shown) and is in rolling contact. A motor and a torque limiter (not shown) are attached to the retard roller 62 so that a driving force acts in the direction opposite to that of the feed roller 60. With this configuration, when the feed roller 60 rotates, the retard roller 62 rotates with the rotation of the feed roller 12a when a rotational force (torque) equal to or greater than a preset torque limiter is applied. .

  Therefore, when there is no recording sheet 54 between the feed roller 60 and the retard roller 62 or when there is one recording sheet 54, the retard roller 62 is rotated when the feed roller 60 rotates, This recording sheet 54 can be carried out.

  Further, when two or more recording sheets 54 are drawn out and conveyed, and there are two or more sheets between the feed roller 60 and the retard roller 62, the frictional resistance between the recording sheets 54 is small, so the rotation applied to the retard roller 62 The force is reduced, and the retard roller 62 rotates in the direction opposite to that of the feed roller 60 to suppress the double feeding of the recording sheet 54.

  In the image forming apparatus main body 10, as shown in FIG. 2, a curved sheet conveyance path (sheet conveyance path) that curves upward from the separation conveyance roller 64 to the downstream side in the recording sheet conveyance direction in the conveyance path of the recording sheet 54. ) The guide member 70 is disposed.

  In a portion from the guide member 70 to the downstream side in the recording sheet conveyance direction, a sheet conveyance roller (takeaway roller) 72 and a registration roller 74 for conveying the recording sheet 54 (image transfer sheet) to the transfer roller 40 are arranged. ing.

  In the paper feeding device provided in the image forming apparatus main body 10, the recording sheet 54 taken out by the pickup roller 58 serving as a recording sheet sending means has a strong pressure contact force acting on the pressure contact area of the feed roller 60 and the retard roller 62 and The sheets are separated one by one by the reverse conveying force of the retard roller 62 and sent out. The sent recording sheet 54 passes through the guide member 70 and is conveyed by the takeaway roller 72. Then, the recording sheet 54 carried into the registration roller 74 by the takeaway roller 72 is conveyed by the registration roller 74 to a transfer region nipped between the photosensitive drum 32 and the transfer roller 40 at a predetermined timing.

  Next, a comparative example for demonstrating the effect of reducing the collision noise generated when the rear end of the recording sheet 54 collides with the paper feed guide members 66 and 68 in the configuration of the paper feed device configured as described above. Will be described with reference to FIGS.

  8 and 9 illustrate a collision state when the rear end of the recording sheet 54 being conveyed collides with the paper feed guide member 166 in the configuration of a conventional general paper feeding device. In the configuration of this conventional general sheet feeding device, as shown in FIG. 8, the trailing end of the recording sheet 54 being conveyed is separated from the leading end of the uppermost recording sheet 54 stacked on the sheet feeding tray. When colliding with the paper feed guide member 166, in the state shown in FIG. 9, the rear end of the recording sheet 54 collides with the paper feed upstream end of the paper feed guide member 166 overhanging. I understood.

  In this conventional general sheet feeding device, such a collision state is caused by pressing the leading edge of the recording sheet 54 against the pressure of the separation conveying roller 64 even when the recording sheet 54 is curled downward due to moisture absorption or the like. In order to guide to the area, it is necessary to dispose the sheet conveying upstream end of the sheet feeding guide member 166 several tens to several mm lower than the leading end of the uppermost recording sheet 54 stacked on the sheet feeding tray 46. This is because the paper feed guide member 166 is disposed sufficiently away from the front wall of the paper feed tray 46 so as not to cause any trouble when the paper feed tray 46 is attached or detached.

  As a result of observing the position of the paper feed guide member 166 and the magnitude of the collision sound with this conventional general paper feeding device, the smaller the overhang amount at the rear end of the recording sheet 54, the smaller the collision noise tends to be. It was found that the collision sound was greatly reduced when there was no overhang. This is because the collision sound generated from the recording sheet 54 is radiated by the vibration of the recording sheet 54 at the time of the collision. In particular, the sound is easily radiated from the rear end portion of the recording sheet 54. This is because when the rear end of the recording sheet 54 has a free end portion that is not constrained (not negotiated with other members), a large vibration is generated and a loud sound is emitted.

  As a result of an experiment comparing the collision noise between the conventional sheet feeding device having the general configuration and the sheet feeding device according to the present embodiment, the sheet feeding device according to the configuration of the present embodiment However, the noise level of the collision sound alone can be reduced by 5 dB (reduced to about 1/3), and the noise level of the entire image forming apparatus including the sheet feeding device according to the configuration of the present embodiment can be reduced by 0.6 dB. The effect was confirmed.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various other configurations can be taken without departing from the gist of the present invention.

1 is an overall perspective view illustrating an image forming apparatus including a paper feeding device according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an internal configuration of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention. FIG. 3 is a perspective view showing a main part of the sheet feeding device according to the embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of a main part taken out and showing a main part on the side of a paper feed guide member integrated with a paper feed tray in a state in which the recording sheet in the paper feeding apparatus starts to be pulled out according to the embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of a main part showing a main part relating to the side of the paper feed guide member separate from the paper feed tray in a state in which the rear end of the recording sheet in the paper feed device is pulled out from the paper feed tray according to the embodiment of the present invention. FIG. FIG. 5 is an enlarged cross-sectional view of a main part showing a main part relating to another configuration of a paper feed guide member in a state in which a trailing end of a recording sheet in the paper feed device is pulled out from a paper feed tray according to the embodiment of the present invention. FIG. 3 is a schematic diagram for explaining a main part of a configuration of a main part of a paper feeding device as a comparative example in order to confirm the effect of the paper feeding device according to the embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating a state in which sound is generated from the rear end of a recording sheet in a paper feeding device as a comparative example. FIG. 10 is an enlarged explanatory view of a main part showing a state in which sound is generated by the trailing edge of a recording sheet protruding from a paper feeding guide member in a paper feeding device as a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus main body 46 Paper feed tray 54 Recording sheet 58 Pickup roller 60 Feed roller 62 Retard roller 64 Separation conveyance roller 66 Paper feed guide member 68 Paper feed guide member 68A Paper feed guide member 70 Guide member

Claims (5)

A paper feed tray for accommodating the recording sheet, a recording sheet delivery means out feed to the pressed region of the contained the recording sheet one by one separated in the paper feed tray, by the recording sheet delivery means, from the paper feed tray A paper feed guide member provided with a guide plane portion for guiding the leading end portion of the drawn recording sheet to the press contact region ,
The radius of the upstream end of the guide plane portion in the conveying direction is from the recording sheet introduction position to the topmost recording paper front end position stored in the paper feed tray with the recording sheet introduction position in the pressure contact area as the center. The sheet feeding device, wherein the guide plane portion is formed to extend along a radiation direction centering on the recording sheet introduction position of the press contact region while extending to the outside of the circular region. 2. The sheet feeding device according to claim 1, wherein the guide plane portion is formed so as to abut on a plane when a rear end portion of the recording sheet held between the press contact areas is lowered . At least a part of the paper feed guide member is formed integrally with the paper feed tray, and the combined portion of the paper feed guide member and the paper feed tray is centered on the recording sheet introduction position of the pressure contact area. 3. The paper feeding device according to claim 1, wherein the paper feeding device is located outside a circular area having a radius from an introduction position to a leading edge position of the uppermost recording paper stored in the paper feeding tray . The sheet feeding guide member according to any one of claims 1 to 3 , wherein the sheet feeding guide member is divided into two in a direction orthogonal to a recording sheet conveyance direction, and is arranged on both sides of the recording sheet feeding means. Paper device. An image forming apparatus comprising the sheet feeding device according to claim 1.

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