JP2010173810A - Recording medium feeding apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress abnormal noises and double feeding when separation means 21 feeds a paper sheet, in a simple structure. <P>SOLUTION: Sliding pressing parts 201b and 202b is provided upstream of a frictional conveying part 203 in a feeding roller 20 that conveys a sheet-like recording medium P by rotational friction. The outer surface of the sliding pressing parts 201b and 202b has a friction coefficient smaller than that of the frictional conveying part 203 and an outer diameter lager than that of the frictional conveying part 203. With such the structure, at the time of starting sheet feeding operation, the separation means 21 is separated from the feeding roller 20 to insert the sheet-like recording medium P between the frictional conveying part 203 and the separation means 21 while the sliding pressing parts 201b and 202b of the feeding roller 20 are in contact with the surface of the separation means 21 and sliding favorably. Thus, the frictional conveying part 203 of the feeding roller 20 having a high friction coefficient is prevented from coming into direct contact with the separation means 21, and therefore abnormal noises due to the distortion or vibration of components, which occur in conventional apparatuses, are reliably prevented from occurring. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording medium feeding device and an image forming apparatus configured to separate a sheet-like recording medium fed by a paper feeding roller by a separating unit.

  In general, in various image forming apparatuses such as copying machines, printers (for example, laser printers, LED printers, etc.), facsimiles, and their multifunctional machines (multifunction printers, etc.) Therefore, a recording medium feeding device including a sheet feeding device configured to feed a sheet-like recording medium such as cut paper to a conveyance path is widely adopted. In the case of an image forming apparatus, a toner image is transferred and fixed on a sheet-like recording medium sent out from the recording medium feeding apparatus, for example, by an image forming process using an electrophotographic method. Such a medium feeding device such as a paper feeding device is usually provided with a paper feeding / separating mechanism for separating and feeding sheet-like recording media one by one.

  As a conventional paper feed separation mechanism, for example, in the mechanism shown in FIG. 10, the separation is made of a high friction member attached to the swinging pressing member 2 on the lower side of the paper feed roller 1 having a substantially half-moon side surface. A pad (friction pad) 3 is known. In this paper feed separation mechanism, the separation pad 3 is pressed toward the paper feed roller 1 by the upward biasing force of the elastic member 4 made of a coil spring or the like. Then, a sheet-like recording medium (illustrated) is utilized by utilizing friction generated between the outer peripheral surface of the paper feed roller 1 and the surface of the separation pad 3 during the paper feed operation, that is, when the paper feed roller 1 is rotationally driven. Are omitted one by one.

  On the other hand, in the sheet feeding / separating mechanism using the separation pad (friction pad) 3, vibrations are likely to occur because the frictional action of the separation pad 3 is used as described above, and so-called noise is generated. May occur. As a countermeasure against such abnormal noise, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 2003-292180) below, on the tangent line (reference numeral S in FIG. 10) at the contact portion between the paper feed roller 1 and the separation pad 3, or The structure which arrange | positions the rotation fulcrum 2a of the pressing member 2 which supports the said separation pad 3 in the vicinity is employ | adopted. If the separation pad 3 having such an arrangement relation is used, the separation pad 3 is surely brought into contact with the paper feed roller 1 and at the same time the wasteful contact state is reduced, and the direction of the force received from the paper feed roller 1 is reduced. Only the component force that is urged at a close angle is generated in the separation pad 3, so that vibration during paper feeding can be suppressed.

JP 2003-292180 A

  However, even in the apparatus according to such a proposal, the parts may be distorted due to the precision of the parts or the acting force generated during feeding, and the direction of the acting force with respect to the rotation fulcrum 2a deviates and vibrates. There is a risk that it cannot be sufficiently suppressed. Further, at the start of paper feeding, the paper feed roller 2 having a high friction coefficient starts to rub against the surface of the separation pad 3 before the sheet-like recording medium starts to rub against the surface of the separation pad (friction pad) 3. For this reason, the above-described distortion of the components and the vibration generated by the distortion tend to increase gradually, and the above-described squeal (abnormal noise) generation phenomenon may not be sufficiently suppressed. .

  The present invention has been made to solve the above-described problems, and is excellent in the occurrence of abnormal noise phenomenon and double feeding phenomenon when paper is fed using a separation means such as a separation pad (friction pad). It is an object of the present invention to provide a recording medium feeding device and an image forming apparatus that can be reduced to the above.

  In order to achieve the above object, in the present invention, the sheet-like recording media fed from the recording media stacking means by the rotational driving of the paper feeding roller having a substantially half moon shape on the side surface are separated one by one by the separating action of the separating means. In the recording medium feeding apparatus configured as described above, the paper feed roller is provided on a friction conveyance unit that conveys the sheet-like recording medium by rotational friction, and on an upstream portion of the friction conveyance unit in a rotation direction of the paper supply roller. And a sliding pressing portion provided, wherein the sliding pressing portion is configured to have a smaller coefficient of friction on the outer peripheral surface and a larger outer diameter as compared with the friction conveying portion. .

  In the recording medium feeding apparatus having such a configuration, when the paper feed roller starts rotating by the start of the paper feed conveyance operation, first, the sliding pressing portion, which is a low friction portion of the paper feed roller, is first placed on the surface of the separating means. The separation means is separated from the paper feeding roller by the pressing force of the sliding pressing portion. At this time, the sliding pressing part slides on the surface of the separating means. However, since the sliding pressing part is a low friction part, the sliding pressing part slides smoothly, and no abnormal noise is generated. Next, the friction conveyance unit, which is a high friction part of the paper feed roller, tries to contact the separation unit. At that time, the sheet-like recording medium that has started feeding is interposed between the friction conveyance unit and the separation unit. Therefore, the friction conveyance unit does not directly contact the surface of the separating unit. Therefore, even during this stage, no abnormal noise is generated in the paper feed, and after that, until the paper feed / conveying operation is completed, the friction conveying portion constituting the part having a high friction coefficient of the paper feeding roller is provided. Since there is no direct contact with the separating means, it is possible to satisfactorily suppress the occurrence of a so-called squealing (abnormal noise) phenomenon based on the distortion and vibration of components as in the prior art.

  In particular, it is desirable that the sliding pressing portion according to the present invention is provided at a position where it comes into contact with the separation means before the most upstream end in the rotational direction of the friction conveying portion contacts the sheet-like recording medium. Moreover, the said sliding press part in this invention can be set as the structure which has a convex-shaped part provided in the rotation direction upstream from the said friction conveyance part.

  According to the recording medium sheet feeding device having such a configuration, the friction conveying unit constituting the portion having a high friction coefficient of the sheet feeding roller is directly connected to the separating unit until the sheet feeding and conveying operation is completed. The contact with the is surely lost.

  At this time, the separating means in the present invention is preferably formed of a plate-like high friction member.

  According to the recording medium feeding device having such a configuration, the separating function of the sheet-like recording medium by the separating unit is surely performed, and double feeding such as double feeding is well prevented. Yes.

  Moreover, it is preferable that the difference in the outer dimension between the sliding pressing portion and the friction conveying portion in the present invention is set in a range of 0.1 mm to 0.6 mm. Furthermore, it is desirable that the separating means in the present invention is configured to be rotated about an axis that is substantially perpendicular to the conveying direction of the sheet-like recording medium. Furthermore, it is desirable that the friction conveying portion in the present invention is formed from a rubber material, and the sliding pressing portion is formed from a mold material. In addition, it is desirable that the friction conveying unit and the sliding pressing unit in the present invention are elastic bodies having different friction coefficients.

  According to the recording medium feeding device having such a configuration, the occurrence of a so-called squeal (abnormal noise) phenomenon based on distortion and vibration of parts as in the prior art is satisfactorily suppressed.

  Further, the above-described recording medium feeding device according to the present invention can be provided as a paper feeding device of the image forming apparatus.

  According to the recording medium feeding device having such a configuration, the above-described operation can be obtained in the image forming apparatus such as a copying machine, and so-called squealing based on the distortion and vibration of parts in the conventional image forming apparatus. The occurrence of (abnormal noise) phenomenon is suppressed satisfactorily.

  As described above, the recording medium feeding device and the image forming apparatus according to the present invention are provided with the sliding pressing portion on the upstream side portion of the friction conveying portion in the paper feeding roller for conveying the sheet-like recording medium by rotational friction, and the sliding By forming the outer peripheral surface of the pressing portion with a smaller coefficient of friction and a larger outer diameter than the friction conveying portion, the sliding pressing portion of the paper feeding roller is brought into contact with the surface of the separating means at the start of the paper feeding conveying operation. The separation means is separated from the paper feed roller while sliding well, and thereafter, a sheet-like recording medium is interposed between the friction conveying section and the separation means, and the paper feed roller has a high coefficient of friction. By preventing the friction conveying part from coming into direct contact with the separating means, it is possible to satisfactorily suppress the occurrence of the so-called squeal (abnormal noise) phenomenon based on the distortion and vibration of parts as in the past. Therefore, with a simple configuration, it is possible to satisfactorily suppress the occurrence of abnormal noise and double feeding when feeding using the separating means, and to reduce the cost of the recording medium feeding device and the image forming apparatus. However, the reliability of the apparatus can be improved.

1 is a longitudinal cross-sectional explanatory view schematically showing the overall structure of a printer as an example of an image forming apparatus to which the present invention is applied. FIG. 2 is an external perspective view illustrating a structure of a paper feed roller according to the first embodiment of the present invention used in the printer illustrated in FIG. 1. FIG. 3 is an external perspective explanatory view showing an enlargement of a paper feed roller shown in FIG. 2. FIG. 4 is an explanatory front view of the paper feed roller shown in FIGS. 2 and 3. FIG. 4 is a longitudinal cross-sectional explanatory view of a paper feed roller shown in FIGS. 2 and 3. FIG. 4 is a longitudinal cross-sectional explanatory view schematically showing a positional relationship between a paper feed roller and a separation pad during paper feeding. FIG. 5 is an explanatory longitudinal cross-sectional view illustrating an enlarged positional relationship between a sheet feeding roller and a separation pad when a sheet feeding and conveying operation is continued. FIG. 6 is an external perspective view illustrating a structure of a paper feed roller according to a second embodiment of the present invention. FIG. 10 is a longitudinal cross-sectional explanatory view schematically showing a positional relationship between a paper feed roller and a separation pad according to a third embodiment of the present invention. It is a longitudinal cross-sectional explanatory drawing showing the schematic structure of the separation mechanism using a general separation pad (friction pad).

  An embodiment of a printer as an example of an image forming apparatus provided with a recording medium feeding device according to the present invention as a paper feeding device will be described in detail with reference to the drawings.

  First, the overall structure of the printer will be described. As shown in FIG. 1, a sheet-like recording medium P such as a plurality of cut sheets is accommodated at the bottom of a main body frame 11 having a hollow casing shape. A universal cassette 12 as a recording medium stacking means is provided so as to be able to be taken in and out in a substantially horizontal direction with respect to the main body frame 11.

  Further, a manual feed tray 15 for feeding a small-sized sheet-like recording medium such as a postcard is provided on one side wall portion (right side wall portion in the drawing) of the main body frame 11. The manual feed tray 15 is provided so as to be rotatable about the lower edge portion 15a, and, as indicated by an arrow A in the figure, an upright closed position represented by a solid line, It is opened and closed between a mounting position that is opened obliquely and represented by a dotted line.

  Further, a discharge tray 13 on which an image-formed sheet-like recording medium is stacked is provided on the upper end surface portion of the main body frame 11 so as to form an inclined surface. In addition, an operation panel (not shown) for inputting the number of prints and the like is disposed on the upper part of the front side portion (the front side portion in FIG. 1) of the main body frame 11. Further, an image forming unit for forming an image on a sheet-like recording medium is provided inside the main body frame 11, and the configuration of the image forming unit will be described next according to the procedure of the image forming operation.

  First, when an image signal is sent from an image processing unit such as an electronic computing device (not shown), the sent image signal is sent by a central processing unit (not shown) provided in the main body frame 11. It is converted into an electrical signal and sent to a known laser irradiation device 14. Laser light (see the alternate long and short dash line B) emitted from the laser irradiation device 14 at the timing of laser irradiation corresponding to the electrical signal is irradiated onto the outer peripheral surface of the photosensitive drum 17 uniformly charged by the charging roller 17a. The electrostatic latent image formed on the photosensitive drum 17 by irradiating the photosensitive drum 17 with the laser beam B is developed and visualized with the developer (toner) T supplied from the developing device 17b, and the photosensitive drum 17 is visualized. A toner image is formed on the outer peripheral surface 17.

  In accordance with such a toner image forming operation, the paper feed roller 20 attached to the front end edge portion (the right end edge portion in FIG. 1) of the universal cassette 12 as the recording medium stacking unit described above is rotationally driven. The universal cassette 12 accommodates a sheet-like recording medium P such as a cut sheet placed on a sheet stacking plate 12a (see FIG. 6) made of a plate-like member. The sheet-like recording medium P is fed out from the inside of the universal cassette 12 in the direction of arrow C (paper feeding direction) in the drawing by the rotational driving of the paper feeding roller 20 having a half moon shape.

  On the other hand, a separation pad (friction pad) 21 as a separating means is provided at the front edge (right edge in FIG. 1) of the universal cassette 12 so as to be positioned below the paper feed roller 20. As described above, the sheet-like recording medium P to be fed is sent out into the conveyance path while being separated one by one by the separating action of the separation pad 21. The separation pad 21 is formed of a plate-like high friction member, and as shown in FIG. 6 in particular, a rotation fulcrum 22a arranged so as to be substantially perpendicular to the conveying direction of the sheet-like recording medium P. Is attached to the swinging end portion of the separation arm 22 that is pivotally attached to the paper feed roller 20 side by an upward biasing force from a pressing spring 22b provided below the separation pad 21. It is pressed.

  Then, the sheet-like recording medium (not shown) sent out from the universal cassette 12 into the conveyance path as described above is conveyed to the transfer area of the photosensitive drum 17 at an appropriate timing, and the transfer provided in the transfer area. The toner image on the photosensitive drum 17 is transferred to the surface of the sheet-like recording medium P by the electrostatic transfer action of the roller 17c. The sheet-like recording medium P to which the toner image has been transferred is conveyed to the fixing device 18, and the toner remaining on the photosensitive drum 17 side after the transfer at this time is transferred to the photosensitive drum 17 by a cleaning blade 17e provided in the cleaning device 17d. It is scraped off from the side.

  Inside the fixing device 18, a heat roller 18a and a press roller 18b are arranged, and the sheet-like recording medium P on which the toner image is formed is nipped between the two rollers 18a and 18b and conveyed. As a result, the toner image is fixed. The sheet-like recording medium on which the toner image has been fixed in this manner is discharged by a pair of discharge rollers 19 and stacked on the discharge tray 13. The sheet feeding / conveying operation can also be performed from the manual feed tray 15 described above, and the procedure for forming an image on the sheet-like recording medium fed from the manual feed tray 15 is the same as described above. .

  As described above, various components and members are incorporated in the printer described above. Among these components, the above-described charging roller 17a, photosensitive drum 17, cleaning device 17d, and developing device 17b are integrated. It is configured to form a process cartridge. This process cartridge is detachably mounted inside the main body frame 11 of the printer.

  Here, the paper feed roller 20 attached to the universal cassette 12 serving as the recording medium stacking unit is configured as follows in the first embodiment shown in FIGS. 2 to 6, for example. Yes. Specifically, as shown in FIG. 2, the paper feed roller 20 according to the first embodiment is a rotary shaft 20a formed by bending a plate-like metal member so as to have a substantially U-shaped cross section. It is attached to a position that is offset to one end side of. A pair of bearing members 20b and 20c are provided at one end portion and a middle portion of the rotary shaft 20a, and the pair of bearing members 20b and 20c are fixed to the main body frame 11 of the printer described above.

  As shown in FIGS. 3 to 5, the main portion of the paper feed roller 20 is formed to have a substantially half-moon-shaped side surface, and a central side frame in the main portion of the paper feed roller 20. A paper feeding color 201 constituting the body is provided. The paper feeding collar 201 extends so as to have a predetermined width dimension in the axial direction, and a flange portion 201a that forms the outermost peripheral portion of the paper feeding collar 201 is provided at one end portion in the axial direction. It has been. Further, a collar restrainer 202 is fitted in the axial direction at the other axial end portion of the paper feeding collar 201. The collar restrainer 202 has substantially the same outer peripheral shape as the flange portion 201a, and is arranged so that the rotational phase has a predetermined relationship with respect to the paper feed collar 201. The sheet feeding collar 201 and the color restraint 202 are made of a material having a low friction coefficient, for example, a mold material such as polyacetal (POM), and have a sliding pressing portion according to the present invention as will be described later. ing.

  Further, a paper feed rubber 203 is attached to the paper feed collar 201 to cover the outer peripheral side portion of the paper feed collar 201 in layers. The paper feed rubber 203 constitutes a friction conveyance unit that conveys a sheet-like recording medium by rotational friction. The paper feed rubber 203 is made of a material having a high friction coefficient, for example, ethylene propylene diene rubber (EPDM). It is formed from rubber materials such as. The outer peripheral surface of the paper feed rubber 203 has a so-called knurled shape formed so as to have a concavo-convex shape at a predetermined minute interval in the rotation direction, and the sheet-like recording medium is conveyed by rotational friction caused by the knurled surface. It has a function to do. That is, the rotation direction of the paper feed roller 20 is set in the direction of arrow D (see FIG. 5) in the figure, so that the sheet-like recording medium P stacked in the universal cassette 12 is sent out to the conveyance path side. It has become.

  Here, ethylene propylene diene rubber (EPDM), which is a material of the above-described feed rubber 203, has a known fact that it has a high friction coefficient such that the friction coefficient with respect to plain paper is around 1.0. . Also, as a known fact, the POM that is the material of the paper feed collar 201 has a low coefficient of friction such that the coefficient of friction with respect to plain paper is around 0.1. The paper feeding collar 201, the color restraint 202 and the paper feeding rubber 203 are substantially half-moon shaped with a part of a hollow cylinder similar to the conventional one cut out, more specifically, slightly larger than 180 ° in the central angle direction. It is formed so as to form an arc shape extending over the angular range.

  For each part having a substantially half-moon shape on the side surface, a part of the flange portion 201a of the paper feed collar 201 and a part of the collar restrainer 202 are more outward in the radial direction than the outermost peripheral portion of the paper feed rubber 203. Protruding slide pressing portions 201b and 202b are provided. As shown particularly in FIG. 5, these sliding pressing portions 201b and 202b are arranged in the rotational direction (arrow D direction) from the upstream edge 203a in the rotational direction (arrow D direction) of the paper feed rubber 203. It arrange | positions in the part to the position advanced only about 40 degrees by the central angle toward the upstream. Further, the difference between the sliding pressing portions 201b and 202b and the external dimensions of the paper feed rubber 203 as the friction conveying portion is set in a range of 0.1 mm to 0.6 mm. In this embodiment, The rotation radius of the sliding pressing portions 201b and 202b is set to be larger by about 0.3 mm than that of the paper feeding rubber 203.

  As described above, the above-described sliding pressing portions 201b and 202b have a convex-shaped portion provided on the upstream side in the rotational direction from the paper feed rubber 203 constituting the friction conveyance portion of the paper feed roller 20. The paper feed collar 201 and the color restrainer 202 are provided so as to protrude outward in the radial direction. The sheet feeding rubber 203 and the sliding pressing portions 201b and 202b as the friction conveying portions are formed of elastic bodies having different friction coefficients, and the sliding pressing portions 201b and 202b constitute the sheet feeding rubber constituting the friction conveying portion. Compared to 203, the outer peripheral surface has a smaller coefficient of friction and a larger outer diameter.

  The above-described sliding pressing portions 201b and 202b abut on the surface of a separation pad (friction pad) 21 as a separation means, so that the separation pad 21 is pushed down and separated from the paper feed roller 20. However, the sliding pressing portions 201b and 202b have an appropriate positional relationship with the paper feed rubber 203 constituting the friction conveyance portion of the paper feed roller 20. That is, when the paper feed roller 20 is driven to rotate with the start of the paper feed conveyance operation, the paper feed rubber 203 as the friction conveyance unit starts to contact the sheet-like recording medium P. 202b is provided at a position where it comes into contact with the surface of the separation pad 21 as the separation means before the rotation direction uppermost stream end portion 203a of the paper feed rubber 203 as the friction conveyance portion starts to contact the sheet-like recording medium P. ing.

  On the other hand, a pair of rollers 20e, 20f are attached to the rotary shaft 20a so as to be rotatable on the outer side in the axial direction of the feeding collar 201 and the color restraint 202 provided on the feeding roller 20 described above. . The pair of rollers 20e and 20f are formed so as to form a disk shape having substantially the same outer diameter, and are formed so that the radius with respect to the paper feed roller 20 is reduced by about 1 mm. . While the outer peripheral surfaces of the rollers 20e and 20f are in contact with the surface of the separation pad 21 described above, the sheet feeding / conveying operation is not performed, but separation is performed against the upward biasing force of the pressing spring 22b. The pad 21 is held at an appropriate position.

  Next, a sheet feeding operation of the sheet-like recording medium P by the sheet feeding device (recording medium feeding device) having the above-described configuration is performed by feeding a sheet feeding roller 20 and a separation pad (separating means) during feeding. The relationship with the friction pad 21 will be described.

  First, when the rotation of the paper feed roller 20 shown in FIG. 6A is stopped, the outer peripheral surfaces of the rollers 20e and 20f provided at both ends in the axial direction of the paper feed roller 20 are the universal cassette 12. The uppermost surface of the sheet-like recording medium P accommodated therein and the upper surface of the separation pad 21 are in press contact. From this state, when the paper feed roller 20 starts to rotate as indicated by an arrow D in FIG. 6B and the paper feed conveyance operation is started, the outer peripheral surface of the paper feed rubber 203 of the paper feed roller 20 is The uppermost sheet-like recording medium P is brought into contact with the surface, and the uppermost sheet-like recording medium P is fed toward the front side of the arrow E in the drawing to start feeding.

  Immediately before the start of such a paper feeding operation, the sliding pressing portions 201b and 202b provided in the paper feeding collar 201 and the color restraint 202 having a radius of rotation larger than that of the paper feeding rubber (friction transporting portion) 203. However, it contacts and presses the upper surface of the separation pad (friction pad) 21, whereby the separation pad 21 is pushed down as the separation arm 22 rotates.

  From this state, when the paper feeding roller 20 is further rotated and the paper feeding / conveying operation is continued as shown in FIG. 6C, the paper feeding / conveying operation by the paper feeding rubber (friction conveying unit) 203 is performed. The sliding pressing portions 201b and 202b provided on the paper feeding collar 201 and the color restraint 202 slide while being pressed against the upper surface of the separation pad (friction pad) 21. At this time, as described above, since the friction coefficient of the sheet feeding collar 201 and the color restraint 202 having the sliding pressing portions 201b and 202b is set to be small, the occurrence of vibration due to contact with the surface of the separation pad 21 is greatly increased. Reduced.

  At this time, the outer diameters of the sliding pressing portions 201b and 202b provided on the paper feeding collar 201 and the color restraint 202 are formed to be slightly larger than the outer diameter of the paper feeding rubber 203. While the sliding pressing portions 201b and 202b provided on the paper collar 201 and the color restraint 202 are in contact with the surface of the separation pad (friction pad) 22, the paper feed rubber (friction transport portion) 203 having a large friction coefficient is separated. It will be maintained in a state separated from the surface of the pad 21. Accordingly, at that time, vibration due to contact between the outer peripheral surface of the paper feed rubber 203 and the surface of the separation pad 21 does not occur (see FIG. 7).

  Further, when the rotation of the sheet feeding roller 20 is continued and the sliding pressing portions 201b and 202b provided in the sheet feeding collar 201 and the color restraint 202 are separated from the surface of the separation pad (friction pad) 21, the sheet feeding rubber ( The outer peripheral surface of the friction conveying unit 203 comes into contact with the surface of the separation pad 21. However, at this timing, the sheet-like recording medium P is interposed between the outer peripheral surface of the paper feed rubber 203 and the surface of the separation pad 21, and the sheet-like recording medium P is fed and separated. It will be. Accordingly, even at this time, there is no direct contact between the outer peripheral surface of the paper feed rubber 203 and the surface of the separation pad 21, or even a slight contact does not cause the occurrence of vibration as in the prior art. .

  As described above, according to the present embodiment, when the paper feed roller 20 starts rotating by the start of the paper feed conveyance operation, first, the sliding pressing portions 201b and 202b, which are low friction portions of the paper feed roller 20, are used as the separating means. The separation pad 21 is separated from the paper feed roller 20 by the pressing force of the sliding pressing portions 201b and 202b. At this time, the sliding pressing portions 201b and 202b slide on the surface of the separation pad 21, but since the sliding pressing portions 201b and 202b are low-friction portions, they slide smoothly and abnormal noise is generated. Is not generated.

  Next, the paper feed rubber (friction transport part) 203, which is a high friction part of the paper feed roller 20, comes to the position of the separation pad 21, but the separation pad 21 at that time was pushed down by the sliding pressing parts 201b and 202b. In the middle of returning from the position, and immediately after that, since the sheet-like recording medium P that has started feeding is interposed between the feeding rubber 203 and the separation pad 21, the feeding rubber 203 is separated. There is no direct contact with the surface of the pad 21, or there is little contact. Therefore, even in this stage, no abnormal noise is generated in the paper feed, and thereafter, the paper feed rubber constituting the part having a high friction coefficient of the paper feed roller 20 until the paper feed conveyance operation is completed. Since the (friction transport unit) 203 does not directly contact the separation pad 21 as the separation means, the occurrence of the so-called squeal (abnormal noise) phenomenon based on the distortion and vibration of the parts as in the prior art is well suppressed. Is done.

  In particular, at the start of the sheet feeding conveyance operation ((b) in FIG. 6), the sheet feeding rubber (friction conveying section) 203 comes into contact with the sheet recording medium P to be in a sliding state, or the sheet recording medium P Even if the stacking position is set upstream of the normal position in the transport direction, the sheet feeding rubber 203 and the separation pad (friction pad) 21 do not come into direct contact with each other, so-called squeal (abnormal noise). The phenomenon never happens. As a result, it is not necessary to lower the friction coefficient of the paper feed rubber 203 and the separation pad 21, so that problems such as double feeding and non-feeding do not occur.

  Next, a second embodiment according to FIG. 8 in which the same components as those in the first embodiment described above are denoted by the same reference numerals will be described. In the present embodiment, color auxiliary members 201c and 202c made of an elastomer resin are attached to the outer peripheral surfaces of the sliding pressing portions 201b and 202b provided in the paper feeding collar 201 and the color restraint 202 of the paper feeding roller 20. . The outer diameters of the color auxiliary members 201c and 202c are set to be 0.6 mm larger than the paper feed rubber 203 as in the first embodiment described above.

  According to the second embodiment having such a configuration, the frictional resistance of the sliding pressing portions 201b and 202b is further reduced by the collar auxiliary members 201c and 202c, and the operation and effect of the first embodiment described above. Can be obtained reliably.

  Furthermore, in the third embodiment according to FIG. 9 in which the same reference numerals are assigned to the same components as those in the first embodiment described above, a separation pad (friction pad) 21 as separation means is provided with the above-mentioned supply. The pressure is provided below the separation pad 21 and the separation arm 32, and is attached to a separation arm 32 that can swing around a shaft 30 that extends substantially parallel to the rotation shaft 20 a of the paper roller 20. It is pressed against the paper feed roller 20 by the upward biasing force from the spring 32b.

  That is, as shown in FIG. 9A, when the rotation of the paper feed roller 20 is stopped, the rollers 20e and 20f provided at both ends in the axial direction of the paper feed roller 20 are in the universal cassette 12. The uppermost surface of the sheet-like recording medium P and the upper surface of the separation pad 21 are in press contact. From this state, when the paper feed roller 20 starts to rotate as indicated by an arrow D in FIG. 9B and starts the paper feed conveyance operation, the paper feed rubber (friction conveyance unit) 203 of the paper feed roller 20 starts. The outer peripheral surface comes into contact with the surface of the uppermost sheet-like recording medium P, and the uppermost sheet-like recording medium P is sent out toward the front side to start the paper feeding / conveying operation.

  Almost simultaneously with the start of the sheet feeding operation, sliding pressing portions 201b and 202b provided on the sheet feeding collar 201 and the collar restrainer 202 having a radius of rotation larger than that of the sheet feeding rubber 203 are used as the separation pad (friction). Pad) 21 and press downward. As a result, the separation pad 21 is pushed down with the rotation of the separation arm 32 around the downstream portion 21a of the separation pad 21 that is in contact with the sliding pressing portions 201b and 202b, and simultaneously swings in the direction of rising. To do. When the separation pad 21 is swung in the rising direction as described above, the sheet-like recording medium P is surely brought into contact with the lower end portion of the separation pad 21 so that the separation operation is performed well. It becomes.

  When the paper feeding roller 20 is further driven to rotate and the paper feeding / conveying operation is continued as shown in FIG. 9C, the paper feeding / conveying operation by the paper feeding rubber (friction conveying unit) 203 is continued. The sliding pressing portions 201 b and 202 b provided on the paper feeding collar 201 and the color restraint 202 slide while pressing against the upper surface of the separation pad (friction pad) 21. At this time, as described above, since the friction coefficient of the sheet feeding collar 201 and the color restraint 202 having the sliding pressing portions 201b and 202b is set to be small, the occurrence of vibration due to contact with the surface of the separation pad 21 is greatly increased. Reduced.

  At this time, the outer diameters of the sliding pressing portions 201b and 202b provided on the paper feeding collar 201 and the color restraint 202 are formed to be slightly larger than the outer diameter of the paper feeding rubber 203. While the sliding pressing portions 201b and 202b provided on the paper collar 201 and the color restraint 202 are in contact with the surface of the separation pad (friction pad) 22, the paper feed rubber (friction transport portion) 203 having a large friction coefficient is separated. It will be maintained in a state separated from the surface of the pad 21. Accordingly, at that time, vibration due to contact between the outer peripheral surface of the paper feed rubber 203 and the surface of the separation pad 21 does not occur.

  Further, when the rotation of the sheet feeding roller 20 is continued and the sliding pressing portions 201b and 202b provided in the sheet feeding collar 201 and the color restraint 202 are separated from the surface of the separation pad (friction pad) 21, the sheet feeding rubber ( The outer peripheral surface of the friction conveying unit 203 comes into contact with the surface of the separation pad 21. However, at this timing, the sheet-like recording medium P is interposed between the outer peripheral surface of the paper feed rubber 203 and the surface of the separation pad 21, and the sheet-like recording medium P is fed and separated. It will be. Accordingly, even at this time, there is no direct contact between the outer peripheral surface of the paper feed rubber 203 and the surface of the separation pad 21, and no vibration is generated as in the prior art.

  As mentioned above, although the embodiment of the invention made by the present inventor has been specifically described, the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention. Nor.

  For example, the materials used in the above-described embodiments are not limited thereto, and other materials can naturally be used as long as they exhibit the functions and effects of the present invention.

  In each of the above-described embodiments, the present invention is applied to a recording medium feeding device of a printer. However, for each recording medium feeding device such as a copying machine and an image forming apparatus including the same. However, the present invention can be similarly applied.

  As described above, the recording medium feeding device and the image forming apparatus according to the present invention can be widely applied to various devices such as a printer and a copying machine.

11 Body frame 12 Universal cassette (recording medium stacking means)
12a Manual feed tray 12b Lower edge 13 Discharge tray 14 Laser irradiation device B Laser light 17 Photosensitive drum 17a Charging roller 17b Developing device 17c Transfer roller 17d Cleaning device 17e Cleaning blade 18 Fixing device 18a Heat roller 18b Press roller T Developer (toner) )
DESCRIPTION OF SYMBOLS 19 Paper discharge roller pair 20 Paper feed roller 20a Rotating shaft 20b, 20c Bearing member 20d Sheet stacking plate 20e, 20f Roller P Sheet-like recording medium 21 Separation pad (separation means)
21a Downstream part 22 Separating arm 22a Rotating fulcrum 22b Pressing spring 201 Paper feeding collar 201a Flange part 201b Sliding pressing part 201c Color auxiliary member 202 Color restraint 202b Sliding pressing part 202c Color auxiliary member 203 Paper feeding rubber (friction conveying part)
203a Upstream edge 30 shaft 32 separation arm 32b pressure spring

Claims (9)

In the recording medium feeding apparatus configured to separate the sheet-like recording media fed from the recording medium stacking unit by the rotation driving of the sheet feeding roller one by one by the separating unit,
The paper feed roller includes a friction transport unit that transports the sheet-like recording medium by rotational friction, and a sliding pressing unit provided in an upstream portion of the friction transport unit in the rotation direction of the paper feed roller,
The sliding medium feeding device is characterized in that the sliding pressing portion is formed so as to have a smaller coefficient of friction on the outer peripheral surface and a larger outer diameter as compared with the friction conveying portion.   2. The sliding pressing portion is provided at a position in contact with the separation means before the most upstream end in the rotational direction of the friction conveying portion contacts the sheet-like recording medium. Recording medium feeding device.   The recording medium feeding apparatus according to claim 1, wherein the sliding pressing portion has a convex portion provided on the upstream side in the rotation direction from the friction conveying portion.   4. A recording medium feeding apparatus according to claim 1, wherein said separating means is formed of a plate-like friction member.   5. The recording medium supply according to claim 1, wherein a difference in outer dimensions between the sliding pressing portion and the friction conveying portion is set in a range of 0.1 mm to 0.6 mm. Feeding device.   6. The recording medium according to claim 1, wherein the separating unit is configured to be rotated about an axis that is substantially orthogonal to the conveyance direction of the sheet-like recording medium. Feeding device.   The recording medium feeding device according to claim 1, wherein the friction conveyance unit is formed of a rubber material, and the sliding pressing unit is formed of a molding material.   The recording medium feeding apparatus according to claim 1, wherein the friction conveying unit and the sliding pressing unit are formed of elastic bodies having different friction coefficients.   An image forming apparatus comprising the recording medium feeding device according to claim 1 as a paper feeding device.

Images