JP2014024631A - Sheet conveyance device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a slip when sheets are conveyed.SOLUTION: A sheet conveyance device includes a separation and feeding roller 4 having a spiral groove 11 formed on its outer peripheral surface for conveying sheets, and a brush 20 that can enter the spiral groove 11 in contact with the outer peripheral surface of the separation and feeding roller 4. The brush 20 removes dust, which has adhered to the separation and feeding roller 4, or feeds the dust into the spiral groove 11. The dust, which has been fed into the spiral groove 11, is pressed by the brush 20, is fed along the spiral groove 11, and is discharged from an end of the separation and feeding roller 4. The separation and feeding roller 4 hardly slips when conveying the sheets because the dust hardly adheres thereto.

Description

  The present invention relates to a sheet conveying apparatus having a function of removing dust attached to the outer periphery of a sheet conveying roller, and an image forming apparatus including the sheet conveying apparatus.

  Generally, an image forming apparatus such as a copying machine, a facsimile, or a printer that forms an image on a sheet, or a sheet processing apparatus that processes sheets such as binding sheets or punching holes, includes a sheet conveying apparatus that conveys the sheet. ing.

  Conventionally, as shown in FIG. 7, the sheet conveying apparatus includes a separation sheet feeding roller 903. The separation paper feeding roller 903 feeds the sheet P fed by the pickup roller 900 from the cassette 901 in which the sheet is stored, with a retard roller 904 having a torque limiter (not shown). Yes. In this case, when the sheets are overlapped, the retard roller 904 is rotated in the direction of the arrow E so as to leave one sheet and return the other sheet to the cassette 901. Further, when the number of sheets fed from the cassette 901 is one, the retard roller 904 is driven to rotate in the direction of the arrow F so as to allow conveyance of one sheet.

  For this reason, the separation sheet feeding roller 903 as a sheet conveying roller must have a friction coefficient with respect to the sheet that causes the retard roller 904 to follow and rotate in the direction of arrow F. However, the separation paper feeding roller 903 has a risk that dust attached to the sheet adheres, the friction coefficient decreases, and slips with respect to the sheet.

  Therefore, in order to reduce slip, a sheet conveying apparatus is disclosed in Patent Document 1 in which creases are formed on the surface of the sheet conveying roller and dust is allowed to escape in the recesses to prevent a reduction in the friction coefficient due to dust.

JP 2010-173823 A

  However, the conventional sheet conveying apparatus has a problem that when the concave portion is filled with dust, the coefficient of friction of the sheet conveying roller is reduced, and the sheet is often slipped.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet conveying apparatus in which dust adhesion is reduced and an image forming apparatus provided with the sheet conveying apparatus.

  In the sheet conveying apparatus of the present invention, a slanting groove is formed on the outer peripheral surface with respect to the rotation axis, and the sheet conveying roller that conveys the sheet and the outer peripheral surface of the sheet conveying roller can contact the groove and enter the groove. A dust removing member, and the groove is directed toward the end of the sheet conveying roller and reaches the end of the sheet conveying roller as it goes upstream in the rotation direction of the sheet conveying roller. It is characterized by that.

  An image forming apparatus according to the present invention includes an image forming unit that forms an image on a sheet and a sheet conveying device that conveys the sheet, and the sheet conveying device is the sheet conveying device described above. .

  The sheet conveying apparatus of the present invention can remove dust adhering to the outer periphery of the sheet conveying roller with the dust removing member. In the sheet conveying apparatus of the present invention, dust can be fed into the groove by the dust removing member, moved along the groove, and discharged from the end of the sheet conveying roller. For this reason, the sheet conveying apparatus of the present invention reduces the amount of dust adhering to the sheet conveying roller, and the sheet conveying roller is less likely to slip with respect to the sheet, so that the sheet can be conveyed smoothly.

FIG. 3 is a cross-sectional view of the image forming apparatus according to the embodiment of the present invention along the sheet conveyance direction. 2 is a control block diagram of the image forming apparatus. FIG. It is sectional drawing along the sheet conveyance direction of the sheet conveying apparatus in embodiment of this invention. FIG. 4 is a diagram of a sheet conveying device viewed from an arrow J direction in FIG. 3. FIG. 5 is a diagram of a separation sheet feeding roller having a groove shape different from that in FIG. 4. 4 and 5 are diagrams of a separation sheet feeding roller having a different groove shape. It is a figure of the conventional sheet conveying apparatus.

  Hereinafter, an image forming apparatus and a sheet conveying apparatus according to an embodiment of the present invention will be described with reference to the drawings. In addition, a numerical value is a reference numerical value, Comprising: It is not a numerical value which limits this invention.

  FIG. 1 is a cross-sectional view of the image forming apparatus according to the embodiment of the present invention along the sheet conveyance direction.

  The image forming apparatus 200 includes an apparatus main body A of the image forming apparatus, and a scanner unit B that is provided on the upper part of the apparatus main body A and reads image information of a book document or a sheet document. The apparatus main body A includes an image forming unit C and a sheet deck D.

  The scanner unit B includes a scanning light source 201, a platen glass 202, a document pressure plate 203 that can be opened and closed with respect to the image forming apparatus main body A, a mirror 204, a light receiving element (photoelectric conversion element) 205, an image processing unit 206, and the like. Yes. The scanner unit B reads a book original or a sheet original placed on the platen glass 202 and pressed against the platen glass 202 by the original pressure plate 203 by scanning the scanning light source 201 in the direction of the arrow. Then, the scanner unit B processes the image information of the document read by the scanning light source 201 by the image processing unit 206, converts it into an electrical signal, and transmits it to the laser scanner 111 of the image forming unit C.

  The apparatus main body A functions as a copying machine when the processing signal of the image processing section 206 is input to the laser scanner 111 of the image forming section C, and functions as a printer when receiving image information from an external apparatus such as a computer or a fax machine. Function. The apparatus main body A can also transmit the processing signal of the image processing unit 206 to an external apparatus.

  Below the image forming unit C, a lower cassette 1a and an upper cassette 1b constituting the sheet deck D are arranged as upper and lower two-stage units denoted by reference numerals U1 and U2. The sheets stored in the cassettes 1a and 1b are fed from the cassette by the pickup roller 3, and are separated and fed one by one by a separation paper feeding roller (feed roller) 4 and a retard roller 5.

  Thereafter, the sheet conveyed to the registration roller pair 106 by the conveyance roller pair 104 and 105 is straightly corrected by the registration roller pair 106 and is adjusted to the position of the image on the photosensitive drum 112 of the image forming unit C. Be fed. The sheet is also fed from the manual feed tray 122.

  On the other hand, the image forming unit C includes a photosensitive drum 112, an image writing optical system 113, a charging roller 116, a developing device 114, a transfer charging device 115, and the like. On the surface of the photosensitive drum 112 uniformly charged by the charging roller 116, a laser beam corresponding to the image information emitted from the laser scanner 111 is scanned by the image writing optical system 113 to form an electrostatic latent image. . The electrostatic latent image is developed by the developing device 114 to become a toner image. The toner image on the photosensitive drum 112 is transferred by the transfer charger 115 to one surface of the sheet fed from the registration roller pair 106 in synchronization with the rotation of the photosensitive drum 112.

  The sheet onto which the toner image has been transferred is continuously conveyed by the conveyance unit 117 and conveyed to the fixing device 118, where it is heated and pressurized to fix the toner image. Then, the sheet is discharged to the discharge tray 120 by the discharge roller pair 119.

  When recording images on both sides of the sheet, the discharge roller pair 119 rotates reversely when the trailing edge of the sheet discharged from the fixing device 118 passes the branch point 207 immediately before the discharge roller pair 119. The sheet is conveyed to the registration roller pair 106 by the conveyance roller pair 104 and 105 through the double-sided tray 121. Thereafter, the toner image is recorded on the other side of the sheet in the same manner as when an image is formed on one side, and is discharged to the tray 120.

  FIG. 2 is a control block diagram of the image forming apparatus.

  A CPU (central processing unit) 304 that controls the overall operation of the image forming apparatus includes a ROM 301 that stores various control programs necessary for the image forming operation, a nonvolatile memory 302 that stores various data related to the image forming operation, and a volatile memory. A memory 303 or the like is connected. The CPU 304 is bus-connected to various actuators 306 involved in the image forming operation via an interface (I / O) 305.

  Next, the sheet conveying apparatus 300 will be described with reference to FIGS. FIG. 3 is a cross-sectional view of the sheet conveying apparatus 300 along the sheet conveying direction. FIG. 4 is a view of the sheet conveying apparatus viewed from the direction of arrow J in FIG.

  The sheet conveying apparatus 300 (FIGS. 1 and 3) feeds the sheet fed from the cassette 1a (or 1b) by the pickup roller 3 to the conveying roller pair 104 by the separation feeding roller 4 and the retard roller 5. It is like that. The cassettes 1a and 1b are provided with a pressing plate 107 having one end as a rotation center and the other end being moved up and down in the direction of arrow K by a motor (not shown). The sheet approaches the pickup roller 3 by the pressing plate 107.

  The retard roller 5 is rotated in the direction of arrow E by a motor (not shown). However, when the rotational force in the direction of arrow G is received from the separation paper feed roller 4 via the sheet P, the retard roller 5 is driven by a torque limiter (not shown). In the direction of the arrow F, it rotates to follow the separation paper feed roller 4.

  A plurality of sheets fed from the cassette 1a (1b) by the pickup roller 3 may overlap. In this case, since the friction of the retard roller 5 with respect to the sheet is larger than the friction between the sheets, the retard roller 5 receiving the rotational force in the direction of the arrow E rotates in the direction of the arrow E, and the separation paper feeding roller Sheets other than the sheet in contact with 4 are returned to the cassette 1a (1b).

  When the number of sheets fed from the cassette 1a (1b) is one, the friction of the separation sheet feeding roller 4 with respect to the sheet is larger than the friction of the retard roller 5 with respect to the sheet. Is fed in the direction of arrow H. At this time, since the retard roller 5 has a torque limiter, the retard roller 5 rotates following the separation sheet feeding roller 4 via the sheet to allow feeding of one sheet.

  As described above, the separation paper feeding roller 4 and the retard roller 5 prevent the double feeding of sheets by the magnitude relation of friction and the torque limiter. Therefore, it is preferable that the friction coefficient of the separation paper feeding roller 4 and the retard roller 5 does not change over a long period of time. However, sheet powder or dust such as dust in the apparatus main body A may adhere to the sheet. If the dust adheres to the separation feed roller 4 and the retard roller 5, the friction coefficient changes, and the sheet The probability of preventing double feeding is reduced. In particular, if the friction coefficient of the separation paper feeding roller 4 changes, there is a possibility that the sheet cannot be fed smoothly.

  Therefore, the sheet conveying apparatus 300 according to the present invention cleans the outer peripheral surface 7c of the separation sheet feeding roller 4 to remove dust adhering to the separation sheet feeding roller 4, and can smoothly convey the sheet for a long period of time. ing.

  In FIG. 4, the separation paper feeding roller 4 has a roller portion 7 made of rubber such as polyurethane, EPDM (ethylene propylene terpolymer), Northorex or the like. The hardness of the surface portion of the roller portion 7 of the separation paper feed roller 4 is 20 ° to 60 °. The hardness is a value read after 3 seconds using a type A dirometer while the meter reading is pressed against the surface of the roller.

  A spiral spiral groove 11 having a width of 1 mm to 5 mm and a depth of 20 μm to 3 mm is formed on the outer peripheral surface 7 c of the roller portion 7 of the separation paper feed roller 4. The width and depth of the spiral groove 11 are based on the fact that the diameter of the component of the sheet powder (such as dolomite) generated from the sheet is about 20 μm. One spiral groove 11 is formed continuously from one end 7a of the roller portion 7 of the separation paper feeding roller 4 to the other end 7b. The spiral groove 11 is not limited to one. Multiple books may be used.

  A brush 20 as a dust removing member is in contact with the outer peripheral surface 7 c of the roller portion 7 of the separation paper feeding roller 4. The brush 20 is disposed along the shaft 6 of the separation paper feeding roller 4. The brush 20 is formed by a metal frame 21 which is attached to a fixing member of the apparatus main body of the image forming apparatus and is grounded, and a brush portion 22 which is provided on the frame 21 and contacts the separation sheet feeding roller 4. . The brush part 22 is formed by arranging SUS fibers at a pitch of 0.4 mm. The tip of the brush portion 22 can enter the spiral groove 11 and can contact the bottom portion 11a. Since the frame 21 is made of metal and the brush portion 22 uses SUS fiber, the brush 20 has conductivity.

  In such a sheet conveying apparatus 300, the separation paper feeding roller 4 sandwiches the sheet with the retard roller 5, rotates in the direction of arrow G (FIG. 3), and conveys the sheet. At this time, dust may adhere to the outer periphery of the separation paper feeding roller 4. However, since the separation paper feed roller 4 has a hardness of 20 ° to 60 °, it is difficult for dust to adhere to the separation paper feed roller 4.

  Even if dust adheres, since the brush portion 22 of the brush 20 is in contact with the outer periphery of the separation paper feed roller 4, the brush portion 22 removes dust as the separation paper feed roller 4 rotates. Or feed into the spiral groove 11.

  The spiral groove 11 is formed obliquely with respect to the rotation axis CL on the outer peripheral surface 7c of the roller portion 7 of the separation paper feeding roller 4 as a sheet conveying roller. The spiral groove 11 is directed toward the end portion 7b of the roller portion 7 of the separation paper feed roller 4 and reaches the end portion 7b toward the upstream side in the rotation direction (arrow G direction) of the separation paper feed roller 4. Is formed. For this reason, a part of the brush portion 22 moves the dust fed into the spiral groove 11 along the spiral groove 11 as the separation paper feeding roller 4 rotates while contacting the bottom 11a of the spiral groove 11. The paper is discharged from the end portion 7 b of the roller portion 7 of the separation paper feeding roller 4.

  Further, since the brush 20 is grounded, the dust, the static electricity of the brush 20 and the separation paper feeding roller 4 can be removed, and the dust can be quickly removed from the separation paper feeding roller 4.

  In this way, the separation sheet feeding roller 4 of the sheet conveying apparatus 300 is less likely to adhere to dust, so that it hardly slips and can convey the sheet smoothly for a long period of time.

  Further, as the number of windings on the separation paper feed roller 4 increases, the spiral groove 11 has an inclination angle of about 90 degrees with respect to the axis CL of the separation paper feed roller 4 and can smoothly guide dust. Therefore, when the spiral groove 11 is formed on the separation sheet feeding roller 4, if the number of windings is selected, the inclination angle of the separation sheet feeding roller 4 with respect to the axis CL can be set to an angle for smoothly guiding dust. Thus, dust removal efficiency can be increased.

  Furthermore, since the spiral groove 11 is formed from one end 7a to the other end 7b, the separation paper feeding roller 4 can remove dust even if it is mounted in the opposite direction in FIG. The In FIG. 4, when it is mounted with the direction reversed left and right, dust is discharged from the end portion indicated by reference numeral 7a. Therefore, the separation sheet feeding roller 4 shown in FIG. 4 in which the spiral groove 11 is formed does not need to be taken into account in mounting, and the sheet conveying apparatus 300 can be easily assembled.

  Alternatively, the spiral roller 11 may be formed on the retard roller 5 and the brush 20 may be brought into contact therewith. In this case, since dust can be discharged from one end or the other end according to the rotation direction of the retard roller, the retard roller 5 can remove dust regardless of the rotation direction.

  As described above, the spiral feeding groove 11 is formed in the separation sheet feeding roller 404 described above, but a V-shaped groove may be formed like the separation sheet feeding roller 404 as the sheet conveying roller shown in FIG. .

  The material and hardness of the separation paper feed roller 404 and the depth and width of the V-shaped groove 411 are the same as those of the separation paper feed roller 4 shown in FIG.

  The separation sheet feeding roller 404 also sandwiches the sheet with the retard roller 5 and rotates in the direction of arrow G to convey the sheet. At this time, dust may adhere to the outer periphery of the separation paper feed roller 404. However, since the hardness of the separation paper feed roller 404 is 20 ° to 60 °, it becomes difficult for dust to adhere to the separation paper feed roller 404. ing.

  Even if dust adheres, the brush portion 22 of the brush 20 removes the dust or feeds it into the spiral groove 11 as the separation paper feeding roller 4 rotates. The V-shaped groove 411 is formed obliquely with respect to the rotation axis CL on the outer peripheral surface 407c of the separation sheet feeding roller 404 as a sheet conveying roller. The V-shaped groove 411 is formed so as to go to the end portions 407 a and 407 b of the roller portion 407 and reach the end portion as it goes upstream in the rotation direction of the separation paper feed roller 404. In other words, the V-shaped groove 411 is formed in a V-shape that widens toward the upstream side in the rotation direction of the separation paper feed roller 404, and both ends reach the end portions 407 a and 407 b of the separation paper feed roller 404.

  For this reason, a part of the brush portion 22 is in contact with the bottom 411 a of the V-shaped groove 411 while the dust fed into the V-shaped groove 411 is in contact with the rotation of the separation paper feeding roller 4, and the V-shaped groove 411. And are discharged from the end portions 407a and 407b of the separation paper feed roller 404.

  Further, since the brush 20 is grounded, the dust, the static electricity of the brush 20 and the separation feed roller 404 can be removed, and the dust can be quickly removed from the separation feed roller 404.

  In this way, the separation paper feed roller 404 is less likely to adhere to dust, and therefore, the separation paper feed roller 404 is less likely to slip and can smoothly convey the sheet for a long period of time.

  As another form of the separation sheet feeding roller 504, like the separation sheet feeding roller 504 as a sheet conveying roller shown in FIG. 6, the inclined grooves 511A and 511B have the inclined directions opposite to each other and the rotation direction of the separation sheet feeding roller 504 (Arrow G) may be alternately formed.

  The material, hardness, and depth and width of the inclined grooves 511A and 511B of the separation sheet feeding roller 504 are the same as those of the separation sheet feeding roller 4 shown in FIG.

  The separation sheet feeding roller 504 also sandwiches the sheet with the retard roller 5 and rotates in the direction of arrow G to convey the sheet. At this time, dust may be deposited on the outer periphery of the separation paper feed roller 504. However, since the hardness of the separation paper feed roller 504 is 20 ° to 60 °, it is difficult for dust to adhere to the separation paper feed roller 504. .

  Even if dust adheres, the brush portion 22 of the brush 20 removes the dust or feeds it into the inclined grooves 511A and 511B as the separation paper feeding roller 504 rotates.

  The inclined groove denoted by reference numeral 511A is formed obliquely with respect to the rotation axis CL on the outer peripheral surface 507c of the separation paper feeding roller 504 as a sheet conveying roller. The inclined groove 511A is located at the end of the roller portion 507 of the separation paper feed roller 504 from the intermediate portion of the separation paper feed roller 504 toward the upstream side in the rotation direction (arrow G direction) of the separation paper feed roller 504. It is formed so as to face 507a and reach the end 507a.

  An inclined groove denoted by reference numeral 511B is also formed obliquely with respect to the rotational axis CL on the outer peripheral surface 507c of the separation paper feeding roller 504 as a sheet conveying roller. The inclined groove 511B also has an end portion of the roller portion 507 of the separation feed roller 504 as it goes from the intermediate portion of the separation feed roller 504 toward the upstream side in the rotation direction (arrow G direction) of the separation feed roller 504. It is formed so as to face 507b and reach the end 507b.

  For this reason, a part of the brush portion 22 moves along the inclined grooves 511A and 511B in accordance with the rotation of the separation paper feed roller 504 while the dust fed into the inclined grooves 511A and 511B is in contact with the bottom portions 511Aa and 511Ba. Move. Then, the brush unit 22 is discharged from the end portions 507 a and 507 b of the separation paper feeding roller 504.

  Further, since the brush 20 is grounded, dust, the static electricity of the brush 20 and the separation feeding roller 504 can be removed, and the dust can be quickly removed from the separation feeding roller 504.

  In this way, the separation paper feeding roller 504 is less likely to adhere to dust, and therefore is less likely to slip and can smoothly convey the sheet for a long period of time.

  Although the above description has described that the present invention is applied to the separation sheet feeding roller 4, the retard roller 5, and the separation sheet feeding rollers 404 and 504, the present invention can also be applied to the conveyance roller pair 104 and 105 in FIG. . Further, the present invention can be applied to a pair of conveyance rollers in a sheet processing apparatus (not shown) that punches a sheet or binds a bundle of sheets.

4, 404, 504: Separation paper feed roller (sheet conveyance roller), 7a, 7b, 407a, 407b, 507a, 507b: end, 7c, 407c, 507c: outer peripheral surface of separation paper feed roller (sheet conveyance roller), 20: brush (dust removing member), 11: spiral groove (groove), 11a: bottom of spiral groove (groove), 200: image forming apparatus, 300: sheet conveying apparatus, 411: V-shaped groove, 411a: V-shaped 511A, 511B: inclined grooves (grooves), 511Aa, 511Ba: bottom portions of inclined grooves (grooves),
A: apparatus main body of image forming apparatus, B: scanner unit, C: image forming unit, D: deck. CL: A rotational axis.

Claims (7)

A sheet conveying roller that conveys a sheet, and a groove that is inclined with respect to the rotation axis is formed on the outer peripheral surface;
A dust removing member that can contact the outer peripheral surface of the sheet conveying roller and enter the groove;
The groove, toward the upstream side in the rotational direction of the sheet conveying roller, is directed toward the end of the sheet conveying roller and reaches the end of the sheet conveying roller.
A sheet conveying apparatus. The groove is formed in a spiral shape,
The sheet conveying apparatus according to claim 1. The groove is formed in a V-shape spreading toward the upstream side of the sheet conveying roller, and both ends reach the end of the sheet conveying roller.
The sheet conveying apparatus according to claim 1. The dust removing member is capable of contacting the bottom of the groove;
The sheet conveying apparatus according to claim 1. The dust removing member is a brush;
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The brush is grounded with electrical conductivity,
The sheet conveying apparatus according to claim 5. An image forming unit for forming an image on a sheet;
A sheet conveying device for conveying the sheet,
The sheet conveying apparatus is the sheet conveying apparatus according to any one of claims 1 to 6.
An image forming apparatus.

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