JP2010173823A - Conveyance roller and paper feeding and conveying device with it and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive conveyance roller with sufficient conveyance durability. <P>SOLUTION: In a roller member structuring the conveyance roller, the ratio of an area S1 where a protruding part 10 is arranged to an area S2 where a recessed part 11 is arranged is set to be within an appropriate range and a rigidity in at least a surface part of the roller member is set to be in an appropriate range. Even when a general material except for polyurethane, for example, a rubber material including olefinic rubber such as EPDM, natural rubber, Norsorex, urethane rubber or urethane foam is used, excellent conveyance function can be obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a conveyance roller provided with an uneven textured portion on a surface of a roller member used for conveyance of a sheet, and a sheet feeding / conveying device and an image forming apparatus including the conveyance roller.

  In general, in an image forming apparatus such as a copying machine, a facsimile machine, a printer, a printing machine, or a bookbinding apparatus, a large number of conveying rollers are used to convey a sheet such as a recording sheet or a document. For example, a pickup roller used as a conveyance roller of a sheet conveyance device is configured to feed a sheet from a sheet tray to a sheet separation unit, and is a separation sheet supply roller provided as a conveyance roller of a multifeed prevention mechanism Is configured to reliably separate and feed sheets one by one. For example, in a paper feeding / conveying device equipped with an FRR double feed prevention mechanism, as shown in FIG. 5, the pickup roller 100 moves the paper (sheet-like recording medium) 102 from the paper tray 101 to the paper separating unit. In the paper separation section, the retard roller 104 provided in contact with the separation paper feeding roller 103 prevents the paper 102 from being double fed. That is, when two or more sheets 102 are fed into the sheet separation unit, the retard roller 104 having a torque limiter (not shown) is not affected by the frictional force of the separation sheet feed roller 103, and thereby the retard roller 104. Is stopped or rotated in the reverse direction to stop the extra paper, and only the uppermost paper 102 in contact with the separation paper feed roller 103 is sent out.

  Various conveying rollers such as the pick-up roller 100 and the separation feeding roller 103 used in such a sheet conveying apparatus are generally made of olefin rubber such as EPDM, natural rubber, northorex, urethane rubber or urethane foam. Although formed from a rubber material, there is a problem that the paper powder generated from the paper adheres when the paper is passed and the friction coefficient tends to decrease. Therefore, for example, in Patent Documents 1 to 3 below, the surface of the polyurethane roller member constituting the conveying roller is provided with a textured surface, that is, a textured part having a convex part (mountain part) and a concave part (sea part). Thus, proposals have been made to make it difficult for paper dust to adhere to the roller surface.

Japanese Patent Laid-Open No. 5-221059 Japanese Patent Laid-Open No. 8-108591 Japanese Patent No. 3744337

  However, since the conventional conveying roller having the textured portion (texture surface) as described above employs polyurethane as a material constituting the roller member, it must be expensive. In addition, there is a problem that hydrolysis tends to occur, and the transport surface peels off and lacks transport durability. Moreover, since the uneven | corrugated | grooved part by microfabrication is required on the roller surface, many processes are required and the cost will also become high in that respect. On the other hand, low-cost EPDM is difficult to produce in terms of outer diameter, and polishing is essential. Under such circumstances, the conveyance roller having a textured portion (texture surface) that has been proposed in the past is not used much in reality.

  SUMMARY An advantage of some aspects of the invention is that it provides a transport roller that is inexpensive and has sufficient transport durability, and a paper feed transport device and an image forming apparatus including the transport roller.

  In order to achieve the above object, in the present invention, in the transport roller provided with a textured portion having a convex portion and a concave portion on the surface of the roller member used for transporting the paper, the surface area of the roller member in the circumferential direction is increased. Among them, the ratio (S1 / S2) of the area S1 where the convex part is provided and the area S2 where the concave part is provided is set within a range of 0.25 to 0.60, A configuration is employed in which the hardness of at least the surface portion of the roller member is set to 20 ° to 45 °.

  According to the present invention having such a configuration, a general processing material other than polyurethane, for example, an olefin type such as EPDM, is set by appropriately setting the embossed portion and hardness of the roller member constituting the conveying roller. Even when a rubber material such as rubber, natural rubber, northorex, urethane rubber or foamed urethane is used, it was confirmed that a good conveying function can be obtained.

  Moreover, in order to obtain the above-mentioned favorable conveyance function reliably, in the present invention, it is preferable that the height dimension from the concave portion to the convex portion is set to 20 μm or more.

  In the present invention, the roller member can have an unpolished surface, and since the surface does not have to be polished, an inexpensive conveying roller can be obtained.

  As described above, the conveyance roller according to the present invention, and the sheet feeding conveyance device and the image forming apparatus including the conveyance roller have an area S1 where the convex portion is provided on the roller member, and an area S2 where the concave portion is provided. Is set within an appropriate range, and the hardness of at least the surface portion of the roller member is set within an appropriate range. General materials other than polyurethane, for example, olefinic rubber such as EPDM, natural rubber, Northolex, Even when a rubber material such as urethane rubber or urethane foam is used, it is constructed so that a good transport function can be obtained, so that it is possible to obtain sufficient transport durability with an inexpensive transport roller without polishing. Therefore, the reliability of the apparatus can be improved at a low cost.

1 is a longitudinal cross-sectional explanatory diagram illustrating an outline of an overall configuration of a copying machine as an example of an image forming apparatus to which the present invention is applied. FIG. 2 is a hardware block diagram illustrating a schematic configuration of an image formation control unit used in the copying machine illustrated in FIG. 1. FIG. 4 is a partially enlarged vertical cross-sectional explanatory view showing an enlarged surface portion of a conveyance roller in an embodiment of the present invention. FIG. 4 is an explanatory plan view schematically illustrating an enlarged surface portion of the conveyance roller illustrated in FIG. 3. FIG. 2 is a longitudinal cross-sectional explanatory view schematically showing an example of a sheet feeding / conveying device used in a copying machine or the like.

  Hereinafter, an embodiment in which the present invention is applied to a copying machine as an image forming apparatus will be described in detail with reference to the drawings.

  First, as shown in FIG. 1, the entire configuration of a copying machine to which the present invention is applied is provided with a scanner unit B, an image forming unit C, and a sheet deck (sheet feeding / conveying device) in each unit of the image forming apparatus main body A. D is provided. A scanner unit B, which is an image reading unit that reads image information of a book document, is disposed above the image forming apparatus main body A, and an image serving as an image forming unit is disposed below the image forming apparatus main body A. A forming unit C is provided, and a sheet deck (paper feeding / conveying device) D is assembled to the lower side of the image forming unit C.

  The scanner unit B described above 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. It consists of each part. Then, a book original or sheet-like original made of a book, recording paper, or the like is placed on the platen glass 202, the original surface is faced downward, the back surface is pressed by the original pressure plate 203, the stationary state is set, and reading is started. When the key is pressed, the scanning system light source 201 scans the lower part of the platen glass 202 in the direction of the arrow to read image information on the document surface. The document image information read by the scanning light source 201 is processed by the image processing unit 206, converted into an electrical signal, and transmitted to the laser scanner 111 of the image forming unit C. Here, the image forming apparatus main body A functions as a copying machine when the processing signal of the image processing unit is input to the laser scanner 111 of the image forming unit C, and functions as a printer when the output signal of the external device (computer) is input. To do. The image forming apparatus main body A also functions as a facsimile apparatus if it receives a signal from another facsimile apparatus or transmits a signal from the image processing unit to another facsimile apparatus.

  On the other hand, a sheet feeding tray 1 constituting a sheet deck (sheet feeding / conveying device) D is mounted below the image forming unit C described above. That is, the sheet feeding tray 1 in the sheet feeding and conveying apparatus constitutes one sheet feeding unit with the lower sheet feeding tray 1a and the upper sheet feeding tray 1b. In this embodiment, two sheet feeding units are provided. A total of four paper feed trays by U1 and U2 can be mounted. One sheet feeding unit U1 disposed on the upper side is detachably attached to the image forming apparatus main body A, and the lower sheet feeding unit U2 is attached to a sheet deck (sheet feeding and conveying apparatus) D. On the other hand, it is detachably attached.

  Sheet-like recording media (paper sheets) such as cut sheets accommodated in the lower sheet feeding tray 1a and the upper sheet feeding tray 1b are fed out by a pickup roller 3 that also constitutes a sheet feeding and conveying device. The sheets are separated and fed one by one by the cooperative action of the separation feed roller (feed roller) 4 and the retard roller 5. That is, when two or more sheet-like recording media are fed into the paper separation unit by the pickup roller 3 described above, the retard roller 5 having a torque limiter (not shown) is affected by the frictional force of the separation paper feeding roller 4. The retard roller 5 stops or rotates in the reverse direction to stop the excessively fed sheet-like recording medium, and only the uppermost sheet in contact with the separation sheet feeding roller 4 is sent out.

  Thereafter, the sheet-like recording medium conveyed to the registration roller 106 by the conveyance rollers 104 and 105 is fed to the image forming unit C in synchronization with an image forming operation described later by the conveyance operation of the registration roller 106. . Further, as a paper feeding / conveying device different from the paper feeding tray 1 described above, a manual feed tray 6 is arranged on the side surface of the image forming apparatus main body A, and a sheet S on the manual feeding tray 6 is fed by a manual paper feeding roller 7. It is fed out to the registration roller 106.

  On the other hand, the image forming unit C includes an electrophotographic 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. Then, a laser beam corresponding to image information emitted from the laser scanner 111 is scanned by the image writing optical system 113 on the surface of the photosensitive drum 112 uniformly charged by the charging roller 116 to form an electrostatic latent image. Then, the electrostatic latent image is developed by the developing device 114 to form a toner image. The toner image on the photosensitive drum 112 is transferred to the first surface of the sheet-like recording medium (paper) fed from the registration roller 106 in synchronization with the rotation of the photosensitive drum 112. It is designed to be transferred at the part.

  Here, reference numeral 117 in the figure indicates a transport unit that transports the sheet-like recording medium on which the toner image is formed as described above, and reference numerals 118 and 119 indicate a fixing device and a discharge roller, respectively. . The conveyance unit 117 is configured to be able to convey a sheet-like recording medium (recording paper) on which a toner image is formed. The sheet-like recording medium on which the toner image is formed is fixed to the fixing device by the conveyance unit 117. After the toner image is fixed on the surface by heating and pressurizing there, it is discharged toward the discharge tray 120 by the discharge action of the discharge roller 119 and stacked there. Yes. As described above, the copying machine as the image forming apparatus shown in FIG. 1 includes the sheet feeding / conveying device D according to the present invention in the image forming unit C, and the sheet-like member fed and conveyed from the sheet feeding / conveying device D. The apparatus is configured to perform image formation.

  When images are recorded on both sides of a sheet-like recording medium (recording paper), the rear end of the sheet-like recording medium discharged from the fixing device 118 passes through the branch point 207 immediately before the discharge roller 119. At that time, the discharge roller 119 is rotationally driven in the reverse direction. As a result, the sheet-like recording medium is temporarily placed on the double-sided tray 121, and thereafter conveyed by the conveying rollers 104 and 105 to reach the registration roller 106, and the reverse side (second surface) of the inverted sheet-like recording medium. ), An image is formed in the same manner as described above, and is then ejected and stacked on the tray 120.

  At this time, each unit that performs the above-described image forming operation is controlled by an image forming control unit as shown in FIG. 2, for example. The image forming control unit according to the present embodiment is roughly composed of a ROM 301 storing various control programs necessary for the image forming operation, a nonvolatile memory 302 and a volatile memory 303 storing various data related to the image forming operation, and various controls. A CPU (Central Processing Unit) 304 that controls the overall operation of the image forming apparatus by executing a program is provided. The CPU 304 is bus-connected to various actuators 306 involved in the image forming operation via a predetermined interface (I / O) 305. A sheet feeding control unit is provided as a program so as to form a part of such an image formation control unit, and the sheet feeding control unit performs an appropriate sheet feeding operation with respect to the sheet feeding / conveying device described above. Is to be executed.

  Next, a description will be given of an embodiment of a transport roller including the above-described pickup roller 3, separation paper feed roller (feed roller) 4, retard roller 5 and the like provided in the paper transport device. That is, the roller members constituting each of the conveying rollers according to the present embodiment are formed of a rubber material that is generally used such as polyurethane, EPDM, or Northolex, and the surface of the roller member is In particular, a textured portion having a convex portion 10 and a concave portion 11 as schematically shown in FIG. 3 is provided. The textured portion is formed so as to have a substantially wave shape along the circumferential direction of the conveying roller (the left-right direction in FIG. 3), and the convex portion 10 is formed to have a mountain shape, The concave portion 11 is formed in a sea shape so as to sink from the convex portion 10.

  The embossed part having the convex part 10 and the concave part 11 in the present embodiment is formed by a chemical forming method of an uneven shape by general chemical etching or the like, or mechanical molding for forming an uneven shape by performing a shot blasting process or the like. Although it can shape | mold by the method etc., these convex part 10 and the recessed part 11 are made | formed as follows.

  That is, in the present embodiment, as shown in FIG. 4 in particular, out of the surface area along the circumferential direction of the roller member constituting each of the transport rollers described above, the area S1 where the convex portion 10 is provided and The ratio S1 / S2 with the area S2 where the recess 11 is provided is set within a range of 0.25 to 0.60. The area S1 of the convex portion 10 and the area S2 of the concave portion 11 are measured by, for example, attaching ink or the like to the surface of the roller member and transferring it to the paper with a load of 300 gf. The area of the ink adhering portion is defined as the area S1 of the convex portion 10, and the area S1 is measured by an image processing apparatus.

  When the above-described area ratio S1 / S2 between the convex portion 10 and the concave portion 11 is less than 0.25, the contact area of the convex portion 10 which is a portion where the roller member is in contact with the sheet (sheet-like recording medium) is reduced. Therefore, the coefficient of friction particularly in the initial stage of use becomes small, the conveyance force becomes insufficient, and the non-feeding of the sheet is likely to occur. In addition, since the contact area between the roller member and the paper is small, the load on each of the convex portions 10 that are the portions where the roller member contacts the paper is increased and the roller member is easily worn. On the other hand, when the area ratio S1 / S2 between the convex portion 10 and the concave portion 11 is larger than 0.60, the contact area of the convex portion 10, which is a portion where the roller member comes into contact with the paper, becomes too large. The paper dust generated from the paper (sheet-like recording medium) is difficult to escape from the paper contact surface of the roller member, and the paper dust adheres to the roller surface. As a result, the maintenance of the friction coefficient is lowered and the conveying force is lowered. Will be. The basis for this point will be clarified in the examples described later.

  On the other hand, it is known that the paper powder component (dolomite or the like) generated from the above-described paper (sheet-like recording medium) reaches a diameter of about 20 μm. Therefore, in this embodiment, as shown in FIG. 3 in particular, the height h1 of the convex portion 10, specifically, the height (distance) from the bottom of the concave portion 11 to the top of the convex portion 10 is shown. ) Is set to 20 μm or more. If it does in this way, paper dust will always protrude from convex part 10, and it will not be buried in crevice 11, and paper dust will be easily separated from a roller member.

  Further, the roller member constituting each of the above-described transport rollers has a hardness of 20 ° to 45 ° at least in the surface portion. The basis of this point will be clarified in the examples described later. For the measurement of the hardness of the roller member, a type A dilometer is used, and the value read after 3 seconds from pressing against the roller surface is defined as the roller hardness.

  As described above, the conveyance roller according to the present embodiment controls the shape and hardness of the surface of the roller member constituting the conveyance roller, so that paper dust generated at the time of passing the sheet is less likely to adhere to the roller surface. Thus, a configuration is adopted in which the maintenance of the friction coefficient during use is equal to or higher than that of the polishing surface roller. In other words, according to the transport roller according to the present embodiment, a general material other than polyurethane, for example, an olefin such as EPDM, is set by appropriately setting the embossed portion and hardness of the roller member constituting the transport roller. It was confirmed as described later that a good transport function can be obtained even when rubber materials such as rubber, natural rubber, northorex, urethane rubber or urethane foam are used.

  In addition, by controlling the shape and hardness of the roller surface, it is relatively easy to set the initial friction coefficient of the transport roller and to estimate the degree of decrease in the friction coefficient after use. Roller design is possible. Furthermore, since the conveyance roller in the present embodiment is a polishing-less roller that does not require polishing, it can be expected to reduce costs by reducing processing costs, and the same performance as a conventional polishing roller while being a polishing-less roller. Can be obtained.

  Here, a description will be given of an embodiment in which an FRR-type sheet feeding / conveying device is configured by the separation feeding roller (feed roller) among the above-described conveying rollers. In each of the following embodiments, a conventional roller member is used as a retard roller disposed opposite to a separation paper feed roller, and a mechanism that stops in a state where a plurality of sheets (originals) are fed is employed. The result of evaluating the sheet conveying force of the separation sheet feeding roller using such a sheet feeding / conveying device will be described below. The transport force of the separation paper feed roller here is defined as the paper transport force when a digital force gauge is attached to the end of the paper and the separation paper feed roller transports the paper while sandwiching the paper. Therefore, it becomes proportional to the friction coefficient of the separation paper feed roller.

First, evaluation regarding the conveyance roller according to Example 1 was performed by using a conventional sheet feeding / conveying device using a conveyance roller having a hardness of 27 ° having a polished surface as a comparison target, and the result is shown in Table 1 below. Show.

  As shown in Table 1 above, in a conventional paper feeding / conveying device using a conveying roller having a hardness of 27 ° on the polished surface, the conveying force drops to around 200 gf when about 20,000 sheets are passed, and the paper (original) is not fed. Etc. occurred.

  On the other hand, Table 2 shows the hardness (roller hardness) of the roller member while fixing the area ratio S1 / S2 between the convex portion 10 and the concave portion 11 in the embossed portion formed on the surface of the roller member to 0.45. The evaluation result regarding the sheet feeding / conveying device when the conveying roller is configured by changing the) is shown. In the table data in this case, the regression line is drawn from the numerical value of the conveying force from 1000 sheets to 15000 sheets when passing up to 15000 sheets, and the number of passing sheets when the conveying force becomes 200 gf is evaluated as the expected durable number. It is a thing.

  As is apparent from Table 2, the range in which the durability effect was recognized with respect to the hardness (roller hardness) of the roller member was 20 ° to 45 °, of which 40 ° was the most effective. .

  Next, a paper feeding / conveying device in which the roller member is fixed by fixing the hardness (roller hardness) to 40 ° and only the area ratio S1 / S2 between the convex portion 10 and the concave portion 11 of the roller member is changed to constitute the conveying roller. The above evaluation results for are shown in Table 3. Here, the conveyance force of the conveyance roller when passing 120,000 sheets was evaluated.

  As can be seen from these results, the conveyance roller having the area ratio S1 / S2 in the range of 0.25 to 0.60 and the hardness of 20 ° to 45 ° has an appropriate initial conveyance force. It has been found that there is little decrease in the conveyance force after the experiment and the durability is excellent. On the other hand, when the area ratio S1 / S2 is less than 0.25, the initial conveying force is small, the conveying force is not stable, and the paper is not fed. Further, when the area ratio S1 / S2 exceeded 0.60, although the initial conveyance force was high, paper powder easily adheres to the surface, resulting in a decrease in the maintenance of the conveyance force.

  Further, even when the area ratio S1 / S2 is satisfied, it has been found that when the hardness is less than 20 °, the wear resistance decreases, and the wrinkle shape on the roller surface is quickly worn. In addition, the paper powder easily bites into the roller, and the paper powder easily adheres to the roller surface. On the other hand, when the hardness exceeds 45 °, the roller hardness is too high, the roller is not properly crushed, the amount of paper sandwiched is reduced, and the conveyance force is insufficient.

  As described above, the conveying roller according to the present invention can be widely applied to a wide variety of image forming apparatuses such as printers and copiers, as well as a sheet feeding apparatus and other apparatuses used in bookbinding apparatuses and printing apparatuses. Is possible.

3 Pickup roller (conveyance roller)
4 Separation paper feed roller (feed roller; transport roller)
5 retard roller (conveyance roller)
DESCRIPTION OF SYMBOLS 10 Convex part 11 Concave part A Image forming apparatus main body B Image reading scanner C Image forming part D Sheet deck (paper feeding conveyance apparatus)
P Sheet-shaped recording medium (paper)
112 Photosensitive drum 115 Transfer roller 118 Fixing device

Claims (5)

In the conveying roller provided with a textured part having a convex part and a concave part on the surface of the roller member used for conveying the paper
Of the surface area along the circumferential direction of the roller member, the ratio (S1 / S2) of the area S1 where the convex portion is provided and the area S2 where the concave portion is provided is 0.25 to 0. Set within the range of 60,
A conveyance roller, wherein a hardness of at least a surface portion of the roller member is set to 20 ° to 45 °.   The conveyance roller according to claim 1, wherein a height dimension from the concave portion to the convex portion is set to 20 μm or more.   The conveying roller according to claim 1, wherein the roller member has a non-polished surface.   A sheet feeding / conveying device comprising the conveying roller according to claim 1 for conveying a sheet-like member.   An image forming apparatus comprising the sheet feeding / conveying device according to claim 4 and configured to form an image on a sheet-like member fed and conveyed from the sheet feeding / conveying device.

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