JP7098916B2 - Sheet feeding device and image forming device - Google Patents

Description

The present invention relates to a seat feeding device and an image forming apparatus including the sheet feeding device.

In an image forming apparatus such as a copier or a printer, paper is separated and fed one by one from a bundle of paper loaded on a paper feed tray, so that separate transfer means such as FRR separation and FR separation are arranged. .. In FRR separation, a separation roller (return roller) to which a constant amount of torque is applied in the anti-feeding direction via a torque limiter is pressed against the feed roller, and paper is separated by a nip between the rollers. In FR separation, a separation roller (friction roller) supported by a fixed shaft is pressed against a feed roller via a torque limiter, and paper is separated by a nip between the rollers.

By the way, in recent years, there has been an increasing tendency to change the paper, which is a recording medium used in an image forming apparatus, to calcium carbonate paper (hereinafter referred to as "calcium carbonate paper") for cost reduction and environmental resistance. This charcoal-cal paper is a paper that contains a large amount of calcium carbonate (hereinafter referred to as "charcoal-cal") instead of pulp. Is easy to adhere and deposit. Then, the frictional force of the roller decreases with time, and paper feed failure (non-feed) and jam due to double feed are likely to occur.

In order to solve such a problem, it has been proposed to make the hardness of the rubber of the feeding roller different from the hardness of the rubber of the separating roller (return roller / friction roller) that is in pressure contact with the feeding roller. For example, in the invention of Patent Document 1 (Japanese Patent No. 3633658), it is proposed to make the rubber hardness of the separating roller harder than the rubber hardness of the feeding roller. By doing so, the slip of the separation roller is suppressed to prevent the charcoal cal from scattering and adhering, and it is easy to carry around with the feeding roller to prevent the occurrence of jam.

However, in the invention of Patent Document 1 (Japanese Patent No. 3633658), the rubber material of the paper feed roller and the rubber material of the separation roller are made of materials having different physical properties to make the rubber hardness different. For this reason, the rubber hardness may change due to environmental factors such as temperature and humidity and changes in the amount of roller wear over time, and it may not be possible to effectively prevent the occurrence of jam.

In addition, the liquid component of the rubber may move from the paper feed roller to the separation roller or from the separation roller to the paper feed roller over time, causing a "swelling" phenomenon in which the volume of the roller on the side where the liquid component has moved increases. There is also. When this swelling occurs, the roller diameter changes and the amount of paper conveyed changes, and the gap between the rollers changes, so that jam is likely to occur.

The present invention has been made in view of such a situation. Due to the stable paper separation action, even if high-charcoal calf paper is used, slippage may occur between the paper and the paper over time, or jam may occur due to a change in roller diameter. It is an object of the present invention to provide a sheet feeding device that suppresses the occurrence of.

In order to solve the above problems, the sheet feeding device of the present invention is a sheet feeding device having a separate transport means for separating and transporting the sheet materials to be fed from the loading portion on which the sheet materials are loaded. The separate transfer means has a feed roller that rotates in the feeding direction of the sheet material, and a separation roller that can press-contact the sheet material with the feed roller by sandwiching the sheet material. And the separation roller are made of the same rubber material, and the feeding roller and the separation roller are fitted to a cylindrical hub portion fixed to the rotation axis of each roller and the outer periphery of the hub portion. The feeding roller has a cylindrical elastic layer to be combined, and the feeding roller has an uneven portion on the outer peripheral surface or the inner peripheral surface of the elastic layer, so that the apparent hardness of the feeding roller can be adjusted to the apparent hardness of the separating roller. The hardness is smaller than the hardness, and the nip shape of the pressure contact portion where the feed roller and the separation roller are in pressure contact with each other is made concave toward the feed roller side.

According to the present invention, by making the apparent hardness of the feeding roller and the separating roller different from each other, the nip shape is made concave on the feeding roller side, so that a stable paper separating action can be obtained and over time. It is possible to suppress the occurrence of slip between the paper and the paper and the occurrence of jam due to changes in the roller diameter.

It is a schematic block diagram of the image forming apparatus which concerns on embodiment of this invention. It is a perspective view of the sheet feeding apparatus which concerns on embodiment of this invention. It is a side view of the sheet feeding apparatus which concerns on embodiment of this invention. (A) is a side view of a roller pair used in the sheet feeding device of the first embodiment of the present invention, and (b) is a side view of a pressurized state. (A) is an assembly perspective view, (b) is an exploded perspective view, and (c) (d) is the feed roller of the roller pair used in the sheet feeding device of the second embodiment of the present invention. It is a side view of the roller pair used. (A) is an assembly perspective view, (b) is an exploded perspective view, and (c) (d) is the feed roller of the roller pair used in the sheet feeding device of the third embodiment of the present invention. It is a side view of the roller pair used. (A) is an assembly perspective view, (b) is an exploded perspective view, and (c) (d) is the feed roller of the roller pair used in the sheet feeding device of the fourth embodiment of the present invention. It is a side view of the roller pair used.

Hereinafter, the sheet feeding device according to the embodiment of the present invention and the image forming device (laser printer) provided with the sheet feeding device will be described with reference to the drawings. In each figure, the same or corresponding parts are designated by the same reference numerals, and the overlapping description thereof will be appropriately simplified or omitted. Further, the dimensions, materials, shapes, relative arrangements thereof, etc. in the description of each component are examples, and the scope of the present invention is not intended to be limited thereto unless otherwise specified.

In the following embodiments, the "sheet material" will be described as "paper". However, the "sheet material" is not limited to paper. The "sheet material" includes not only paper (paper) but also transparencies, fabrics, metal sheets, plastic films, and prepreg sheets in which carbon fibers are preliminarily impregnated with resin.

The "sheet material" also includes media to which a developing agent and ink can be attached, a recording medium, a recording paper, a recording sheet, and the like. In addition to plain paper, "paper" also includes thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, and the like.

Further, the "image formation" used in the following description is not only to give an image having a meaning such as characters or figures to the medium, but also to give an image having no meaning such as a pattern to the medium. Also means.

(Laser printer configuration)
FIG. 1 is a configuration diagram schematically showing a configuration of a color laser printer as an embodiment of an image forming apparatus provided with the sheet feeding device of the present invention. The color laser printer 100 includes four process units 1K, 1Y, 1M, and 1C as image forming means. These process units form an image with a developer of each color of black (K), yellow (Y), magenta (M), and cyan (C) corresponding to the color separation component of the color image.

Each process unit 1K, 1Y, 1M, 1C has the same configuration except that it has toner bottles 6K, 6Y, 6M, 6C containing unused toners of different colors. Therefore, the configuration of one process unit 1K will be described below, and the description of the configuration of the other process units 1Y, 1M, and 1C will be omitted.

The process unit 1K has an image carrier 2K (for example, a photoconductor drum), a drum cleaning device 3K, and a static elimination device. The process unit 1K further includes a charging device 4K as a charging means for uniformly charging the surface of the image carrier, and a developing device as a developing means for performing visible image processing of the electrostatic latent image formed on the image carrier. It has 5K and the like. The process unit 1K is detachably attached to the main body of the laser printer 100, and consumable parts can be replaced at the same time.

The exposure device 7 is arranged above each process unit 1K, 1Y, 1M, 1C installed in the laser printer 100. The exposure device 7 is configured to perform write scanning according to image information, that is, to emit laser light from a laser diode based on image data.

In this embodiment, the transfer device 15 is arranged below each process unit 1K, 1Y, 1M, 1C. The primary transfer rollers 19K, 19Y, 19M, and 19C are arranged so as to face the image carriers 2K, 2Y, 2M, and 2C and abut against the intermediate transfer belt 16.

The intermediate transfer belt 16 circulates in a state of being hung on the primary transfer rollers 19K, 19Y, 19M, 19C, the drive roller 18, and the driven roller 17. The secondary transfer roller 20 is arranged so as to face the drive roller 18 and abut against the intermediate transfer belt 16. If the image carriers 2K, 2Y, 2M, and 2C are the first image carriers of each color, the intermediate transfer belt 16 is the second image carrier obtained by synthesizing those images.

The belt cleaning device 21 is installed on the downstream side of the secondary transfer roller 20 in the traveling direction of the intermediate transfer belt 16. Further, the cleaning backup roller is installed on the side opposite to the belt cleaning device 21 with respect to the intermediate transfer belt 16.

The paper feed tray 50 having a loading portion for loading the sheet material is installed below the laser printer 100, and can accommodate a large number of sheets P in a bundle. The paper feed tray 50 can be inserted into and removed from the main body of the laser printer 100 for replenishing paper and the like. The paper feed roller 60 and the roller pair 210 as the transport means are arranged above the paper feed tray 50 installed in the laser printer 100, and the uppermost paper P of the paper feed tray 50 is supplied from the paper feed tray 50. It is designed to be transported toward the paper path 32.

The resist roller pair 250 as the separation and transfer means is arranged on the immediate upstream side of the secondary transfer roller 20 in the transfer direction, and the paper P fed from the paper feed tray 50 can be temporarily stopped. This temporary stop forms a slack on the tip side of the paper P.

A resist sensor 31 is arranged on the upstream side of the resist roller pair 250 immediately in the transport direction, and the resist sensor 31 detects the passage of the paper tip portion. When a predetermined time elapses after the resist sensor 31 detects the passage of the tip portion of the paper, the paper is abutted against the resist roller pair 250 and temporarily stopped.

The paper feed roller 60 and the roller pair 210 are arranged in the unitized sheet feeding device 200 as shown in FIGS. 2A and 2B. At the downstream end of the sheet feeding device 200, as shown in FIG. 2B, a transport roller 240 for transporting the paper transported to the right side from the roller pair 210 upward is arranged. As shown in FIG. 1, the transport roller 240 transports the paper toward the upper resist roller pair 250.

The roller pair 210 is composed of a pair of upper and lower rollers. The roller pair 210 may be an FRR separation method or an FR separation method. In the FRR separation method, a separation roller (return roller) to which a constant amount of torque is applied in the counterfeeding direction via a torque limiter by a drive shaft is pressed against a feed roller to separate paper by a nip between the rollers. In the FR separation method, a separation roller (friction roller) supported by a fixed shaft is pressed against a feed roller via a torque limiter, and paper is separated by a nip between the rollers.

In this embodiment, the roller pair 210 is configured by the FRR separation method. That is, the roller pair 210 is a feed roller 220 on the upper side that conveys paper to the inside of the machine, and a separation roller 230 on the lower side that is given a driving force by a drive shaft in the direction opposite to the feed roller 220 via a torque limiter. It is composed of.

The separation roller 230 is urged toward the feed roller 220 by an urging means such as a spring. The paper feed roller 60 rotates counterclockwise in FIG. 2B by transmitting the driving force of the feed roller 220 via the clutch means.

The paper P, which is abutted against the resist roller pair 250 and has slack formed, has the secondary transfer roller 20 and the drive roller 18 in accordance with the timing at which the toner image formed on the intermediate transfer belt 16 is suitably transferred. It is sent to the secondary transfer nip. Then, on the fed paper P, the toner image formed on the intermediate transfer belt 16 is electrostatically transferred to a desired transfer position with high accuracy by the bias applied in the secondary transfer nip portion. It has become.

The post-transcriptional transfer path 33 is arranged above the secondary transfer nip portion of the secondary transfer roller 20 and the drive roller 18. The fixing device 34 is installed near the upper end of the post-transcriptional transfer path 33. The fixing device 34 includes a fixing roller 34a containing a heat generating source such as a halogen lamp, and a pressurizing roller 34b that rotates while abutting on the fixing roller 34a at a predetermined pressure. As the fixing device 34, other configurations such as those using an endless rotating belt and an IH heating method are also possible.

The post-fixing transport path 35 is arranged above the fixing device 34, and is branched into a paper discharge path 36 and a reverse transport path 41 at the upper end of the post-fixing transport path 35. A switching member 42 is arranged at this branch portion, and the switching member 42 swings around the swing shaft 42a. Further, a paper ejection roller pair 37 is arranged near the opening end of the paper ejection path 36.

The reverse transfer path 41 joins the paper feed path 32 at the other end opposite to the branch portion. A pair of reversing transport rollers 43 is arranged in the middle of the reversing transport path 41. The paper output tray 44 is installed on the upper part of the laser printer 100 in a concave shape in the inward direction of the laser printer 100.

The powder container 10 (for example, a toner container) is arranged between the transfer device 15 and the paper feed tray 50. The powder container 10 is detachably attached to the main body of the laser printer 100.

The laser printer 100 of the present embodiment requires a predetermined distance from the paper feed roller 60 to the secondary transfer roller 20 due to the transfer paper transfer. Then, the powder container 10 is installed in the dead space generated at this distance to reduce the size of the entire laser printer.

The transfer cover 8 is installed above the paper feed tray 50 and in front of the paper feed tray in the drawing direction. Then, by opening the transfer cover 8, the inside of the laser printer 100 can be inspected. The transfer cover 8 is provided with a manual paper feed roller 45 for manual paper feed and a manual paper feed tray 46 for manual paper feed.

The laser printer of this embodiment is an example of an image forming apparatus, and the image forming apparatus is not limited to a laser printer. That is, the image forming apparatus can be configured as any one of a copying machine, a facsimile, a printer, a printing machine, and an inkjet recording device, or a multifunction device in which at least two or more of these are combined.

(Laser printer operation)
Next, the basic operation of the laser printer according to the present embodiment will be described below with reference to FIG. First, a case of performing single-sided printing will be described. As shown in FIG. 1, the paper feed roller 60 is rotated by a paper feed signal from the control unit of the laser printer 100. Then, the paper feed roller 60 separates only the uppermost paper of the bundled paper P loaded on the paper feed tray 50 and sends it out to the paper feed path 32.

When the tip of the paper P fed by the paper feed roller 60 and the roller pair 210 reaches the nip portion of the resist roller pair 250, the paper P forms a slack and stands by in that state. Then, the optimum timing (synchronization) for transferring the toner image formed on the intermediate transfer belt 16 to the paper P is set, and the tip skew of the paper P is corrected.

In the case of manual feeding, the bundled paper loaded on the manual feeding tray 46 passes through a part of the reversing transport path 41 by the manual feeding roller 45 one by one from the topmost paper, and the resist roller vs. 250 nip. It is transported to the part. Subsequent operations are the same as feeding paper from the paper feed tray 50.

Here, regarding the image-creating operation, one process unit 1K will be described, and the description of the other process units 1Y, 1M, and 1C will be omitted. First, the charging device 4K uniformly charges the surface of the image carrier 2K at a high potential. Then, the exposure device 7 irradiates the surface of the image carrier 2K with the laser beam L based on the image data.

On the surface of the image carrier 2K irradiated with the laser beam L, the potential of the irradiated portion is lowered to form an electrostatic latent image. The developer 5K has a developer carrier that supports a developer containing toner, and an electrostatic latent image is formed on the unused black toner supplied from the toner bottle 6K via the developer carrier. Transfer to the surface portion of the image carrier 2K. The image carrier 2K to which the toner is transferred forms (develops) a black toner image on its surface. Then, the toner image formed on the image carrier 2K is transferred to the intermediate transfer belt 16.

The drum cleaning device 3K removes the residual toner adhering to the surface of the image carrier 2K after the intermediate transfer process. The removed residual toner is sent to the waste toner accommodating portion in the process unit 1K by the waste toner transport means and collected. Further, the static eliminator removes the residual charge of the image carrier 2K from which the residual toner has been removed by the cleaning device 3K.

Also in the process units 1Y, 1M and 1C of each color, a toner image is formed on the image carriers 2Y, 2M and 2C in the same manner, and the toner images of each color are transferred to the intermediate transfer belt 16 so as to overlap each other.

The intermediate transfer belt 16 transferred so that the toner images of each color overlap each other travels to the secondary transfer nip portion of the secondary transfer roller 20 and the drive roller 18. On the other hand, the resist roller pair 250 sandwiches the paper abutted against the resist roller pair 250 at a predetermined timing and rotates, and the toner image formed by superimposition transfer on the intermediate transfer belt 16 is preferably transferred at the same timing. It is conveyed to the secondary transfer nip portion of the secondary transfer roller 20. In this way, the toner image on the intermediate transfer belt 16 is transferred to the paper P fed by the resist roller pair 250.

The paper P on which the toner image is transferred is transferred to the fixing device 34 through the transfer path 33 after transfer. Then, the paper P conveyed to the fixing device 34 is sandwiched between the fixing roller 34a and the pressure roller 34b, and the unfixed toner image is fixed to the paper P by heating and pressurizing. The paper P on which the toner image is fixed is sent out from the fixing device 34 to the transport path 35 after fixing.

The switching member 42 is in a position where the vicinity of the upper end of the transfer path 35 after fixing is open as shown by the solid line in FIG. 1 at the timing when the paper P is sent out from the fixing device 34. Then, the paper P sent out from the fixing device 34 is sent out to the paper ejection path 36 via the transport path 35 after fixing. The paper ejection roller pair 37 sandwiches the paper P sent out to the paper ejection passage 36 and is rotationally driven to eject the paper to the paper ejection tray 44, thereby completing single-sided printing.

Next, a case of performing double-sided printing will be described. As in the case of single-sided printing, the fixing device 34 feeds the paper P to the paper ejection path 36. When double-sided printing is performed, the paper ejection roller pair 37 transfers a part of the paper P to the outside of the laser printer 100 by rotational driving.

Then, when the rear end of the paper P passes through the paper discharge path 36, the switching member 42 swings around the swing shaft 42a as shown by the dotted line in FIG. 1, and closes the upper end of the transport path 35 after fixing. do. Almost at the same time as the closing of the upper end of the transport path 35 after fixing, the paper ejection roller pair 37 rotates in the direction opposite to the direction in which the paper P is transported to the outside of the laser printer 100, and feeds the paper P to the reverse transport path 41.

The paper P sent out to the reverse transfer path 41 passes through the reverse transfer roller pair 43 and reaches the resist roller pair 250. Then, the resist roller pair 250 measures the optimum timing (synchronization) for transferring the toner image formed on the intermediate transfer belt 16 to the toner image untransferred surface of the paper P, and sends the paper P to the secondary transfer nip portion. ..

Then, the secondary transfer roller 20 and the drive roller 18 transfer the toner image to the toner image untransferred surface (back surface) of the paper P when the paper P passes through the secondary transfer nip portion. Then, the paper P on which the toner image is transferred is conveyed to the fixing device 34 through the transfer path 33 after transfer.

The fixing device 34 sandwiches the conveyed paper P by the fixing roller 34a and the pressure roller 34b, heats and pressurizes the paper P, and fixes the unfixed toner image on the back surface of the paper P. In this way, the paper P on which the toner images are fixed on both the front and back surfaces is sent out from the fixing device 34 to the transport path 35 after fixing.

The switching member 42 is in a position where the vicinity of the upper end of the transfer path 35 after fixing is open as shown by the solid line in FIG. 1 at the timing when the paper P is sent out from the fixing device 34. Then, the paper P sent out from the fixing device 34 is sent out to the paper ejection path 36 via the fixing transfer path. The paper ejection roller pair 37 sandwiches the paper P sent out to the paper ejection path 36, is rotationally driven, and discharges the paper to the paper ejection tray 44 to complete double-sided printing.

After the toner image on the intermediate transfer belt 16 is transferred to the paper P, residual toner is attached on the intermediate transfer belt 16. The belt cleaning device 21 removes this residual toner from the intermediate transfer belt 16. Further, the toner removed from the intermediate transfer belt 16 is conveyed to the powder container 10 by the waste toner conveying means and collected in the powder container 10.

(Roller vs. roller)
Next, the rollers used for the roller pair 210 of the sheet feeding device 200 according to the embodiment of the present invention will be described with reference to FIGS. 3 to 6. 3 to 6 show different embodiments 1 to 4, respectively.

In all embodiments, the feed roller 220 and the separation roller 230 of the roller pair 210 have rubber elastic layers 222 and 232. The rubber material of the elastic layers 222 and 232 is completely the same rubber material for the feeding roller 220 and the separating roller 230 in order to prevent "swelling" described later.

The rubber material is a polymer substance having rubber elasticity at room temperature or a material thereof, and is natural rubber (NR), isoprene rubber (IR), styrene butadiene rubber (SBR), ethylene propylene rubber (EPDM), chloroprene rubber ( CR), acrylonitrile butadiene rubber (NBR), urethane rubber (U), epichlorohydrin rubber (CO, ECO), silicone rubber (Q), fluorine rubber (FKM) and the like can be adopted.

Further, in all the embodiments, the apparent hardness of the separating roller 230 is made harder than the apparent hardness of the feeding roller 220. The magnitude relationship of this apparent hardness is due to the difference in the geometric structure of the rollers. Therefore, the separation roller 230 is rotated forward without being affected by environmental factors such as temperature and humidity and changes in the amount of roller wear over time. Performance and separation performance can be improved. The improvement in forward rotation performance and separation performance due to the magnitude relationship of hardness has already been verified in Table 1-19 of Patent Document 1.

There are two types of "hardness": "standard hardness" and "apparent hardness". The "standard hardness" conforms to each test method, and the dimensions and shape of the test piece satisfy the regulations. The "apparent hardness" does not satisfy the specified dimensions and shape of the test piece even if it complies with each test method (see JIS K 6253-2).

The present invention is characterized in that the feeding roller 220 and the separating roller 230 have different "apparent hardness" to form a nip shape in which the feeding roller 220 side has a concave shape. The "apparent hardness" of the elastic layers 222 and 232 of the feeding roller 220 and the separating roller 230 can be changed by the "rubber thickness" of the respective elastic layers 222 and 232.

The first to third embodiments described below have different methods of changing the "rubber thickness". In the fourth embodiment, the thickness of the rubber itself is not changed, and the "apparent hardness" is made different depending on the uneven portion of the outer peripheral surface of the hub portion 221.

(First Embodiment)
3A and 3B show a first embodiment, in which FIG. 3A shows a non-pressurized state of the feeding roller 220 and the separating roller 230, and FIG. 3B shows a pressurized state of the feeding roller 220 and the separating roller 230. Is shown. The lower separation roller 230 is urged toward the upper feed roller 220 by an elastic force such as a spring, so that the paper can be pressed against the feed roller 220 with the paper sandwiched between them. A nip N having a predetermined contact pressure is formed between the rollers.

The feeding roller 220 and the separating roller 230 have a rigid cylindrical hub portion 221 and 231 fixed to the rotating shaft of the roller, and a cylindrical elastic layer 222 fitted to the outer periphery of the hub portions 221 and 231, respectively. 232 and. The hub portions 221 and 231 have an inner cylinder 221a and 231a fitted to the rotation shaft of the roller, an outer cylinder 221b and 231b, and a plurality of spokes 221c and 231c connecting these in the radial direction. The rotating shaft of the roller is fitted into the holes 221d and 231d of the inner cylinders 221a and 231a.

The feeding roller 220 and the separating roller 230 have substantially the same diameter. This facilitates separation and transfer of paper between both rollers. It is most preferable that both rollers have the same outer diameter, but they do not have to have exactly the same diameter. One roller may be within twice, 1.5 times, 1.2 times, etc. of the other roller.

The radial thickness of the elastic layer 222 of the feeding roller 220 is thicker than the radial thickness of the elastic layer 232 of the separating roller 230. In this first embodiment, the apparent hardness of the separation roller 230 is made harder than the apparent hardness of the feeding roller 220 by making the elastic layers 222 and 232 different in radial thickness as described above. That is, due to the difference in apparent hardness, the shape of the nip N of the feeding roller 220 and the separating roller 230 is such that the separating roller 230 bites into the feeding roller 220 as shown in FIG. 3B, that is, the feeding roller. The 220 side has a concave nip shape.

In FIG. 3B, the shape or diameter of the separation roller 230 is hardly changed as compared with FIG. 3A. Since the elastic layer 232 of the separation roller 230 has elasticity similar to the elastic layer 222 of the feeding roller 220, the shape or diameter of the separation roller 230 is actually small but deformed. However, by setting the difference in the radial thickness of the elastic layers 222 and 232 described above as appropriately large, for example, 2: 1, the minute deformation amount exerted on the nip shape in which the feeding roller 220 side has a concave shape. The impact can be virtually ignored.

Hysteresis friction force at the nip N increases due to the upward convex nip shape as shown in FIG. 3 (b). Hysteresis frictional force is the frictional force on the roller surface generated by the force that the deformed rubber tries to return to its original shape.

Further, the amount of radial deformation (pushing amount) of the separation roller 230 can be reduced by the upward convex nip shape. As a result, a long distance from the outer peripheral surface of the elastic layer 232 to the rotation center of the hub portion 231 can be secured, and the rotational force for rotating the separation roller 230 forward can be reduced.

Then, since the rotational force of the feeding roller 220 can be applied to the upward convex nip N that secures a long distance to the rotation center of the hub portion 231 with a high surface pressure applied, the separation roller 230 can be subjected to the rotational force. Forward rotation performance is improved. Therefore, when a sheet of paper is sandwiched between the nip N and fed, smooth feeding without slipping with the paper is performed due to the high forward rotation performance and the increase in the hysteresis friction force, and particularly high charcoal cal. When paper is used, the separation roller 230 does not slip, so that it is possible to prevent the charcoal from falling off.

When a plurality of sheets of paper are sandwiched between the nip N, a reliable transfer action without slip can be obtained for the upper layer paper due to the increase in the hysteresis friction force, while the relative of the separation roller 230 for the lower layer paper. A reliable separation action can be obtained by improving the separation performance due to the large apparent hardness and the upward convex nip N.

Further, since the rubber materials of the elastic layers 222 and 232 of the feeding roller 220 and the separating roller 230 are completely the same, the liquid component of the rubber is transferred from the feeding roller 220 to the separating roller 230 or from the separating roller 230. It can be moved to the feed roller 220 to prevent "swelling" from occurring.

The liquid component of rubber exudes from compounding agents (vulcanizing agents, vulcanization accelerators, reinforcing agents, antiaging agents, fillers, plasticizers, colorants, etc.) and is a mineral such as gasoline and lubricating oil. Contains oils, various animal and vegetable oils, solvents, chemicals, etc. When the "swelling" occurs, the diameters of both rollers change, and eventually the paper transport amount changes, increasing the possibility of jam. However, in the embodiment of the present invention, since the rubber materials of the feeding roller 220 and the separating roller 230 are completely the same to prevent the occurrence of swelling, it is possible to prevent the occurrence of jam due to swelling.

(Second Embodiment)
FIG. 4 shows the feeding roller 220 of the second embodiment, in which (a) is an assembled state of the rollers, (b) is an disassembled state, and (c) and (d) are roller pairs using the feeding roller 220. Is shown.

The feeding roller 220 has an uneven portion formed on the outer peripheral surface of the elastic layer 222. This uneven portion is formed by forming ridges 222a and dents 222b extending in the axial direction of the feeding roller 220 alternately at equal intervals in the circumferential direction. The hub portion 221 is fitted inside the elastic layer 222 from the direction of the arrow in FIG. 4 (b). This hub portion 221 is the same as that used in the first embodiment.

The cross-sectional shape of the uneven portion is rectangular in the illustrated example, but the uneven portion can be any other shape such as a trapezoid or a triangle. Further, it is also possible to make a wrinkle-like pattern having a depth of less than 1 mm by mold transfer, or to make a polished grain pattern by polishing.

By forming the uneven portion on the outer peripheral surface of the elastic layer 222 in this way, the apparent hardness of the elastic layer 222 can be softened. FIG. 4 (c) is a roller pair 210 using the feed roller 220 of (a). The lower separation roller 230 uses the same one as in the first embodiment.

As shown in FIG. 4C, the separating roller 230 is formed with an uneven portion on the outer peripheral surface of the elastic layer 222 of the feeding roller 220, and the elastic layer 222 of the separating roller 230 is an inner outer peripheral surface without the uneven portion. The apparent hardness of can be made relatively hard. Therefore, even when the elastic layer 222 of the feeding roller 220 and the elastic layer 232 of the separating roller 230 have the same thickness, the apparent hardness of the separating roller 230 is made relatively hard, and the pressure contact portion between the two rollers is pressed against each other. The nip shape can be concave on the feed roller 220 side.

Further, even when the uneven portion formed by the ridges 232a and the concave 232b is formed not only on the outer peripheral surface of the elastic layer 232 of the separation roller 230 as well as the feeding roller 220 as shown in FIG. 4D, the height of the uneven portion is formed. By making the height lower than the uneven portion of the feeding roller 220, the apparent hardness of the separating roller 230 is made relatively hard as in the above-described embodiment, and the nip shape is made concave toward the feeding roller 220 side. be able to.

(Third Embodiment)
FIG. 5 shows the feeding roller 220 of the third embodiment, (a) is an assembled state of the roller, (b) is a disassembled state, and (c) and (d) are a roller pair using the feeding roller 220. Is shown.

The feeding roller 220 has an uneven portion formed on the inner peripheral surface of the elastic layer 222. This uneven portion is formed by forming ridges 222a and dents 222b extending in the axial direction of the feeding roller 220 alternately at equal intervals in the circumferential direction. The hub portion 221 is fitted inside the elastic layer 222 from the direction of the arrow in FIG. 5 (b). This hub portion 221 is the same as that used in the first embodiment.

The cross-sectional shape of the uneven portion is rectangular in the illustrated example, but the uneven portion can be any other shape such as a trapezoid or a triangle. Further, it is also possible to make a wrinkle-like pattern having a depth of less than 1 mm by mold transfer, or to make a polished grain pattern by polishing.

By forming the uneven portion on the inner peripheral surface of the elastic layer 222 in this way, the apparent hardness of the elastic layer 222 can be softened. FIG. 5 (c) is a roller pair 210 using the feed roller 220 of (a). The lower separation roller 230 uses the same one as in the first embodiment.

As shown in FIG. 5 (c), an uneven portion is formed on the inner peripheral surface of the elastic layer 222 of the feeding roller 220, and the elastic layer 222 of the separation roller 230 is an inner outer peripheral surface without the uneven portion. The apparent hardness of 230 can be made relatively hard. Therefore, even when the elastic layer 222 of the feeding roller 220 and the elastic layer 232 of the separating roller 230 have the same thickness, the apparent hardness of the separating roller 230 is made relatively hard as in the above-described embodiment. The nip shape of the pressure contact portion with which the rollers are in pressure contact can be concave on the feed roller 220 side.

Further, even when the uneven portion formed by the ridges 232c and the concave 232d is formed not only on the inner peripheral surface of the elastic layer 232 of the separation roller 230 as well as the feeding roller 220 as shown in FIG. 5D, the uneven portion of the uneven portion is formed. By making the height lower than the uneven portion of the feeding roller 220, the apparent hardness of the separating roller 230 is made relatively hard as in the above-described embodiment, and the nip shape is made concave toward the feeding roller 220 side. can do.
(Fourth Embodiment)
FIG. 6 shows the feeding roller 220 of the fourth embodiment, (a) is an assembled state of the roller, (b) is a disassembled state, and (c) and (d) are a roller pair using the feeding roller 220. Is shown.

The feeding roller 220 has an uneven portion formed on the outer peripheral surface of the hub portion 221. In this uneven portion, the ridges 221e and the concave ridges 221f extending in the axial direction of the hub portion 221 are formed alternately at equal intervals in the circumferential direction. The hub portion 221 is fitted inside the elastic layer 222 from the direction of the arrow in FIG. 6 (b). This hub portion 221 is the same as that used in the first embodiment.

The cross-sectional shape of the uneven portion is rectangular in the illustrated example, but the uneven portion can be any other shape such as a trapezoid or a triangle. Further, it is also possible to make a wrinkle-like pattern having a depth of less than 1 mm by mold transfer, or to make a polished grain pattern by polishing.

By forming the uneven portion on the outer peripheral surface of the hub portion 221 in this way, the apparent hardness of the elastic layer 222 fitted to the outside thereof can be softened. FIG. 6 (c) is a roller pair 210 using the feed roller 220 of (a). The lower separation roller 230 uses the same one as in the first embodiment.

As shown in FIG. 6C, an uneven portion is formed on the outer peripheral surface of the hub portion 221 of the feeding roller 220, and the hub portion 231 of the separation roller 230 is an outer peripheral surface without the uneven portion, whereby the separation roller 230 is provided with an uneven portion. The apparent hardness can be made relatively hard. That is, the inner peripheral surface of the elastic layer 222 of the feeding roller 220 partially bites into the uneven portion of the outer peripheral surface of the hub portion 221 due to the pressure acting on the nip N, whereas the separation roller 230 is elastic because it has no uneven portion. There is no room for layer 232 to escape. Therefore, even when the elastic layer 222 of the feeding roller 220 and the elastic layer 232 of the separating roller 230 have the same thickness, the apparent hardness of the separating roller 230 is made relatively hard, and the pressure contact portion between the two rollers is pressed against each other. The nip shape can be concave on the feed roller 220 side.

Further, even when the uneven portion formed by the ridges 231e and the concave ridges 231f is formed not only on the outer peripheral surface of the hub portion 231 of the separation roller 230 as well as the feeding roller 220 as shown in FIG. 6D, the height of the uneven portion is formed. By making the height lower than the uneven portion of the feeding roller 220, the apparent hardness of the separating roller 230 is made relatively hard, and the nip shape is made concave toward the feeding roller 220 side, as in the above-described embodiment. can do.

Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above-described embodiment and can be variously modified within the scope of the technical idea described in the claims. Needless to say. For example, the "concavo-convex portion" may be configured by forming a plurality of protrusions and recesses in the circumferential direction on the inner peripheral surface or the outer peripheral surface of the elastic layer of the roller or the outer peripheral surface of the hub portion.

Further, the "concavo-convex portion" can be composed of a plurality of protrusions or dents formed in a scattered pattern, and in that case, by changing the height or depth, formation density or diameter of the protrusions or dents, the feeding roller can be used. The apparent hardness of the separation roller can be different. Further, the uneven portions, protrusions or dents, and the foamed elastic layer may have different apparent hardnesses of the feeding roller 220 and the separating roller 230 by combining two or more of them.

Further, the apparent hardness of the feeding roller and the separating roller may be different by forming the foamed elastic layer on the elastic layer of the feeding roller. As the material of the foam elastic layer, for example, a resin foam or a rubber foam having a closed cell structure can be used. When a foamed elastic layer is also formed on the elastic layer of the separating roller, the apparent hardness of both rollers is made different by making the foaming ratio of the foamed elastic layer of the feeding roller larger than the foaming ratio of the foamed elastic layer of the separating roller. Can be done.

1C, 1M, 1Y, 1K: Process unit 2C, 2M, 2Y, 2K: Image carrier
3C, 3M, 3Y, 3K: Drum cleaning device 4C, 4M, 4Y, 4K: Charging device
5C, 5M, 5Y, 5K: Developer 6C, 6M, 6Y, 6K: Toner bottle 7: Exposure device 8: Transfer cover 10: Powder container 15: Transfer device 16: Intermediate transfer belt 17: Driven roller 18: Drive Rollers 19C, 19M, 19Y, 19K: Primary transfer roller 20: Secondary transfer roller 21: Belt cleaning device 31: Resist sensor 32: Paper feed path 33: Post-transfer transfer path 34: Fixing device 34a: Fixing roller 34b: Pressurization Roller 35: Transfer path after fixing 36: Paper discharge path 37: Paper output roller pair 41: Inverted transfer path 42: Switching member 42a: Swinging shaft 43: Inverted transfer roller pair 44: Paper discharge tray 45: Paper feed roller 46: Bypass tray 50: Paper tray 60: Paper roller 100: Color laser printer 200: Sheet feeder 210: Roller pair 220: Paper roller 221: Hub part 221e: Convex 221f: Concave 222: Elastic layer 222a: Convex 222b: Concave 230: Separation roller 231: Hub 232: Elastic layer 240: Conveyor roller 250: Resist roller vs. L: Laser beam N: Nip P: Paper

Japanese Patent No. 3633658

Claims (7)

A sheet feeding device having a separate and transporting means for separating and transporting the sheet materials to be fed from a loading unit on which the sheet materials are loaded, wherein the separate and transporting means is used.
A feeding roller that rotates in the feeding direction of the sheet material,
It has a separation roller that can be pressed against the feed roller with the sheet material sandwiched between them.
The feeding roller and the separating roller are made of the same rubber material.
The feeding roller and the separating roller are fixed to the rotating shafts of the respective rollers in a cylindrical shape.
It has a bump portion and a cylindrical elastic layer fitted to the outer periphery of the hub portion.
The feeding roller has an uneven portion on the outer peripheral surface or the inner peripheral surface of the elastic layer, so that the apparent hardness of the feeding roller is made smaller than the apparent hardness of the separating roller.
A sheet feeding device characterized in that the nip shape of the pressure contact portion where the feeding roller and the separating roller are in pressure contact with each other is concave on the feeding roller side. The sheet feeding device according to claim 1 , wherein the uneven portion has a plurality of ridges and dents formed in the axial direction of the roller. The sheet feeding device according to claim 1 , wherein the uneven portion has a plurality of ridges and dents formed in the circumferential direction of the roller. The sheet feeding device according to claim 1 , wherein the uneven portion has a plurality of protrusions formed in a scattered spot shape. The sheet feeding device according to claim 1 , wherein the uneven portion has a plurality of recesses formed in a scattered spot shape. The sheet feeding device according to any one of claims 1 to 5 , wherein the feeding roller and the separating roller are formed to have substantially the same diameter. An image forming apparatus comprising the sheet feeding device according to any one of claims 1 to 6 and an image forming means for forming an image on a sheet material fed from the sheet feeding device.

Images