JP6801228B2 - Sheet feeding device, image forming device and image reading device - Google Patents

Description

The present invention relates to a sheet feeding device, an image forming device, and an image reading device.

The paper feed device used in the image forming device transports the paper by pressing the paper placed on the bottom plate in the sheet (hereinafter, represented by paper) storage unit against the paper feed roller, and the friction arranged downstream. A method of separating paper one by one with a member (for example, a separation pad member) is already known (see, for example, Patent Document 1).

In the conventional friction separation method using a friction member, in order to improve the separation performance, the pressing force of the spring that presses the friction member against the paper feed roller has been increased. However, there is a limit to increasing the pressing force, and as a side effect, non-feeding occurs and abnormal noise occurs in the separation pad portion. Further, when papers having significantly different friction coefficients between papers (particularly replenished papers and different types of papers) are used, there is a problem that double feeding cannot be eliminated by increasing the pressing force for separation.

The present invention has been made in view of the above circumstances, and even when sheets having a significantly different coefficient of friction between sheets (for example, replenished paper or different types of paper) are used due to a simple configuration. An object of the present invention is to provide a sheet feeding device capable of reliably preventing double feeding.

In order to achieve the above object, the present invention comprises a rotary feeding member that contacts one surface of a sheet and feeds the sheet downstream along a predetermined transport path, and faces the rotary feeding member. A friction member arranged at a position sandwiching the transport path and forming a separation nip in contact with the rotary feeding member, and a pedestal for holding the friction member on the opposite side of the separation nip. in the sheet feeding apparatus, wherein a downstream side in the sheet conveyance direction than the separation nip, provided with a projection portion in the width direction orthogonal to the sheet conveying direction of the holding surface of the cradle of the friction member Rutotomoni, the holding The surface, the protrusion, and the pedestal on the downstream side of the protrusion in the sheet transport direction have steps in order, and the protrusion is surrounded by the friction member and the holding surface of the pedestal. A space is formed, the protrusion is provided with a length substantially the same as the separation nip, a constant height in the width direction, and a constant length in the sheet transport direction , and the space is the space. When there are a plurality of sheets having substantially the same length as the separation nip and having a constant height in the width direction and passing through the separation nip, the rotary feed among the plurality of sheets is provided. The tips of the plurality of remaining sheets other than the first sheet are stopped while deforming the friction member so that the first sheet in contact with the feeding member is smoothly conveyed. , In the seat feeding device that is configured respectively .

According to the present invention, it is possible to reliably prevent double feeding even when sheets having significantly different friction coefficients between sheets are used by the above simple configuration, and it is possible to reliably prevent double feeding from the protrusions in the sheet transport direction. Since the friction member end is locked to the cradle on the downstream side, the friction member end does not tremble , and jamming due to sheet turning, skewing, etc. can be prevented .

It is external perspective view of the color laser printer as an image forming apparatus to which this invention is applied. It is a schematic overall block diagram of the color laser printer of FIG. It is a side view around a paper feed tray and a feed roller arranged in a general separation pad type sheet feed device. It is sectional drawing of the sheet separation part of the sheet feeding apparatus of FIG. It is a perspective view which shows the main part of the sheet feeding apparatus of Embodiment 1. FIG. It is a perspective view of the cradle and the separation pad in a state where the paper feed roller is removed from the sheet feeding device of Embodiment 1. It is a perspective view which shows the cradle and the protrusion with the paper feed roller and the separation pad removed from the sheet feeding apparatus of Embodiment 1. FIG. (A) is a schematic cross-sectional view showing a main part of a conventional sheet feeding device, and (b) is a schematic cross-sectional view showing a main part of the sheet feeding device according to the first embodiment of the present invention. (A) is a schematic cross-sectional view for explaining the operation when one sheet of paper is fed by the sheet feeding device of the first embodiment, and (b) is the sheet feeding device of the first embodiment when two sheets of paper are fed twice. It is a schematic cross-sectional view explaining the separation operation.

Hereinafter, embodiments of the present invention (hereinafter, referred to as “embodiments”) including examples will be described in detail with reference to the drawings. As long as there is no risk of confusion, the components (members, components) and the like having the same function and shape, etc. in each embodiment will be described once and then the same reference numerals will be given to omit the description. In order to simplify the figures and explanations, even if the components should be represented in the figure, the components that do not need to be specifically described in the figure may be omitted without notice. When a component of a published patent gazette or the like is cited and explained, the reference numeral thereof shall be shown in parentheses to distinguish it from that of each embodiment or the like.

In the following description, "paper", which is an example of "sheet" and "sheet-like recording medium", will be described as a representative, but the sheet is not limited to paper (paper), but OHP sheets, cloths, and other developers and inks. Includes all so-called recording media, recording paper, recording paper, transfer paper, etc. to which the above can be attached. Further, the "sheet" is not limited to a flexible one, but also includes a hard plate-shaped one and a relatively thick one.

The meanings of the terms used in the description of the present specification are as follows. "Rotation" means circular motion in the forward and reverse directions, "shaft support" means rotatably supporting the shaft, and "contact" means contacting the abutted state. "" Means to be arranged or provided, or to be provided at a fixed position, and "urging" means to increase the momentum.

In addition, the dimensions, materials, shapes, relative arrangements, etc. in the description of each component and each member are merely examples, and the scope of the present invention is limited to them unless otherwise specified. Absent.

(Laser printer configuration)
A configuration of a color laser printer as an example of an image forming apparatus to which the present invention is applied will be described with reference to FIGS. 1 and 2. FIG. 1 is an external perspective view of a color laser printer as an image forming apparatus to which the present invention is applied, and FIG. 2 is a schematic overall configuration diagram of the color laser printer of FIG.
The sheet feeding device of the present invention can be applied to, for example, a sheet feeding device of an image forming device or an image reading device. The color laser printers shown in FIGS. 1 and 2 include four process units 1K, 1Y, 1M, and 1C. In these process units, an image is formed by 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 as a representative below, and the description of the configuration of the other process units 1Y, 1M, and 1C will be omitted.

The process unit 1K includes a drum cleaning device 3K, a static elimination device, a charging device 4K, a developing device 5K, etc., which are arranged around an image carrier 2K (for example, a photoconductor drum) that can rotate clockwise. Have. The process unit 1K is a so-called process cartridge that is detachably attached to the main body of the color laser printer and the 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 this color laser printer. The exposure device 7 is a laser light writing device configured to emit laser light from a laser diode based on color-separated image data.
The exposure device 7, the four process units 1K, 1Y, 1M, 1C, and the transfer device 15 described above constitute an image forming means or an image forming device.

In this embodiment, the transfer device 15 is arranged below each process unit 1K, 1Y, 1M, 1C, and includes a primary transfer device, an intermediate transfer belt 16, a secondary transfer device, and the like. The primary transfer rollers 19K, 19Y, 19M, and 19C as the primary transfer device are arranged so as to face the image carriers 2K, 2Y, 2M, and 2C and are in contact with the intermediate transfer belt 16.

The intermediate transfer belt 16 is an intermediate transfer body composed of an endless belt, and circulates in the direction of the arrow shown in the drawing while being hung on the primary transfer rollers 19K, 19Y, 19M, 19C, the driving roller 18, and the driven roller 17. It is designed to do.

The secondary transfer roller 20 constituting the secondary transfer device 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 carries the toner images supported by the image carriers 2K, 2Y, 2M, and 2C. It can be said that it is an image carrier of 2.

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 cleaning roller of the belt cleaning device 21 with respect to the intermediate transfer belt 16.

The paper feed tray 30 is installed below the color laser printer and can accommodate a large number of sheets P in a bundle. The paper feed tray 30 is removable from the device main body of the color laser printer for replenishing paper and the like. The paper feed roller 47 is arranged above the paper feed tray 30 installed in the color laser printer, and feeds / feeds the paper P of the paper feed tray 30 from the paper feed tray 30 toward the paper feed path 31. It is designed to do.

The resist roller pair 14, which is also called a timing roller pair, is arranged on the immediate upstream side of the secondary transfer roller 20, and can temporarily stop the paper P fed from the paper feed tray 30. By this temporary stop, a slack is formed on the tip side of the paper P.

The slack-formed paper P is sent out to the secondary transfer separation nip of the secondary transfer roller 20 and the drive roller 18 at the timing when the toner image formed on the intermediate transfer belt 16 is suitably transferred. Then, on the paper P that has been sent out, the toner image formed on the intermediate transfer belt 16 by the secondary transfer separation nip is transferred to a desired transfer position with high accuracy.

The post-transcriptional transfer path 33 is arranged above the secondary transfer separation nips of the secondary transfer roller 20 and the drive roller 18. The fixing device 34 is installed near the upper end of the transfer path 33 after transfer.
The fixing device 34 includes, for example, a fixing roller 34a incorporating a heat generating source such as a halogen lamp, and a pressurizing roller 34b that rotates while being pressed against the fixing roller 34a at a predetermined pressure. 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 the branch portion between the paper ejection path 36 and the reversing transfer path 41. The switching member 42 is swing-driven 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 31 at the other end of the branch portion. A reverse transfer roller pair 43 is arranged in the middle of the reverse transfer path 41. The output tray 44 is installed on the upper part of the color laser printer so as to form a concave shape inward of the color laser printer.

The powder container 10 is, for example, a toner container, and is arranged between the transfer device 15 and the paper feed tray 30. The powder container 10 is detachably attached to the main body of the color laser printer.

The color laser printer of the present embodiment requires a predetermined distance from the paper feed roller 47 to the secondary transfer roller 20 due to the transfer of transfer paper. 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 30 and in front of the paper feed tray in the drawing direction. Then, by opening the transfer cover 8, the inside of the color laser printer can be inspected. The transfer cover 8 is provided with a manual feed roller for manual paper feed and a manual paper feed tray for manual paper feed.

The color laser printer of this embodiment is an example of an image forming apparatus, and the image forming apparatus is not limited to the laser printer. That is, the image forming apparatus is configured as a copying machine, a facsimile, a printer, a printing machine including a stencil printing machine, an offset printing machine, etc., and an inkjet recording device, or a compound machine in which at least two or more of these are combined. It is also possible to do. Further, an image reading device having an automatic document transporting device (ADF) for feeding a document which is a sheet on which an image to be read is formed may be added to the multifunction device.

(Operation of color laser printer)
Next, the basic operation of the color 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. 2, the paper feed roller 47 rotates according to a paper feed signal from a control unit provided in the color laser printer. Then, the paper feed roller 47 separates only the uppermost paper of the bundled paper P loaded on the paper feed tray 30, and sends it out to the paper feed path 31.

When the tip of the paper P fed by the paper feed roller 47 reaches the nip portion of the resist roller pair 14, it forms a slack and stands by in that state. That is, the optimum timing (synchronization) for transferring the toner image formed on the intermediate transfer belt 16 to this paper is taken, and the tip skew of the paper P is corrected.

In the case of manual paper feeding, the bundled paper loaded on the manual paper feed tray passes through a part of the reversing transport path 41 by the manual feeding roller one by one from the topmost paper, and the resist roller pairs 14 It is transported to the nip part of. Subsequent operations are the same as paper feeding from the paper feed tray 30.

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 a 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.

Then, the developing device 5K transfers the unused black toner supplied from the toner bottle 6K to the surface portion of the image carrier 2K on which the electrostatic latent image is formed. Then, the image carrier 2K to which the toner is transferred forms (develops) a black toner image on the surface thereof. The toner image formed on the image carrier 2K is transferred to the intermediate transfer belt 16.

The drum cleaning device 3K removes residual toner adhering to the surface of the image carrier 2K after undergoing the intermediate transfer step. The removed residual toner is sent to the waste toner storage unit in the process unit 1K by the waste toner transport means provided in the color laser printer and collected. At this time, 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.

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 as in the process unit 1K described above, and the toner images of each color are overlapped on the intermediate transfer belt 16. Transcribe.

The intermediate transfer belt 16 transferred so that the toner images of each color overlap each other is subjected to the transfer bias applied to the secondary transfer roller 20 when traveling to the secondary transfer separation nip of the secondary transfer roller 20 and the drive roller 18. The toner image on the intermediate transfer belt 16 is transferred to the paper P fed by the resist roller pair 14.

Here, the paper P is sent out to the secondary transfer separation nip at the timing when the toner image formed by being transferred so as to be overlapped on the intermediate transfer belt 16 is preferably transferred. Then, on the paper P that has been sent out, the toner image formed on the intermediate transfer belt 16 by the secondary transfer separation nip is transferred to a desired transfer position with high accuracy.

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 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 transport path 35 after fixing is open as shown by the solid line in FIG. 2 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 while being guided by the switching member 42 at a position where the vicinity of the upper end of the transport path 35 is open after fixing. The paper P sent out to the paper discharge path 36 is sandwiched between the paper discharge rollers 37 and rotationally conveyed, and is discharged to the paper discharge tray 44 to complete single-sided printing.

Next, a case where double-sided printing is performed will be described. As in the case of single-sided printing, the fixing device 34 feeds the paper P to the output path 36. When performing double-sided printing, the paper ejection roller pair 37 is rotationally conveyed to convey a part of the tip of the paper P to the outside of the color laser printer.

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 broken line in FIG. 2, and closes the upper end portion of the transport path 35 after fixing. To do. Then, substantially at the same time as the closing of the upper end portion of the transport path 35 after fixing, the paper ejection roller pair 37 rotates in the direction opposite to the direction of transporting the paper P to the outside of the color laser printer, and feeds the paper P to the reverse transport path 41.

The paper P sent out to the reversing transfer path 41 reaches the resist roller pair 14 after being conveyed by the reversal transfer roller pair 43. At this time, the resist roller pair 14 transfers the paper P to the secondary transfer separation nip while taking the optimum timing (synchronization) for transferring the toner image formed on the intermediate transfer belt 16 to the toner image non-transfer surface of the paper P. Send to.
Subsequent transfer operations for transferring the paper P to the toner image non-transfer surface, paper transport operation after transfer, and fixing operation for the paper P transferred to the toner image non-transfer surface are performed in almost the same manner as the single-sided printing operation described above. The double-sided printing is finished.

Further, the operation of removing the residual toner on the intermediate transfer belt 16 by the belt cleaning device 21, the transfer of the toner removed from the intermediate transfer belt 16 to the powder container 10 by the waste toner transfer means, and the subsequent powder transfer. The operation of collecting the toner in the container 10 is also performed in the same manner as described above.

(Basic configuration of a general separation pad type sheet feeder)
Next, with reference to FIGS. 3 and 4, the basic configuration of a conventional sheet feeding device of a general separation pad type will be described. FIG. 3 is a side view of the paper feed tray 30 and the paper feed roller 47 arranged in a conventional sheet feeding device of a general separation pad type as viewed from the side, and FIG. 4 is a sheet feeding device of FIG. It is sectional drawing of the sheet separation part of.

As shown in FIG. 3, the paper feed roller 47 feeds and conveys paper as an example of a sheet to the downstream side of the sheet transfer direction X along a predetermined transfer path (hereinafter, also referred to as transfer). It functions as a rotary feeding member constituting the means, and is arranged on the device main body side. The bottom plate 46 and the cradle 49 are respectively arranged in the paper feed tray 30.

The bottom plate 46 is configured so that a bundle of paper as a bundle of sheets can be loaded and the topmost paper can be pressed against the paper feed roller 47. The pedestal 49 is a member that attaches (pastes) and supports the separation pad 48 as an example of the friction member.

The paper feed roller 47 has a paper feed roller shaft 50 and a roller portion integrally formed on the outer peripheral portion of the paper feed roller shaft 50, and the paper feed roller shaft 50 is rotated by a D-shaped cut or a pin or the like. It is stopped and rotatably supported by the device body via bearings.
The paper feed roller shaft 50 is formed so as to extend in the sheet transport direction X and the direction orthogonal to the paper surface of FIG. 3 (hereinafter, referred to as the width direction Y). A drive gear is attached to the shaft end of the paper feed roller shaft 50.

The drive gear is connected to a drive source such as a motor via a plurality of idle gears or drive connecting members such as a clutch and a solenoid. The driving force is transmitted from the drive source to the paper feed roller shaft 50, and the paper feed roller 47 is configured to rotate counterclockwise in FIG.
By controlling the connection time of the drive connection member and the stop time of the drive source, the paper feed roller 47 is configured to operate intermittently at a predetermined timing.

The surface layer portion of the paper feed roller 47 is made of rubber having a high coefficient of friction so that a predetermined conveying force can be applied to the paper P. Then, the paper P is fed (hereinafter, also referred to as paper feeding or conveying) by controlling the connecting time of the drive connecting member and the stop time of the drive source.

The dimensions of the paper feed roller 47 can be, for example, 36 mm in diameter and 45 mm in width. As for the dimensions, an appropriate feeding roller dimension can be selected according to the type of paper P to be supported by the sheet feeding device and the space in the device main body / device.

The bottom plate 46 of the paper feed tray 30 is pivotally supported by a bottom plate rotation shaft 51 provided in the paper feed tray 30 so as to be rotatable (swing) within a predetermined angle range. The bottom plate 46 is always urged upward by a spring.

The paper P is placed on the bottom plate 46 described above, and the uppermost paper P is in contact with the paper feed roller 47 in a contact state. The paper P is provided with a conveying force by the urging force of the spring and the friction coefficient of the paper feed roller 47, and can be conveyed in the sheet conveying direction X in the diagonally right direction of FIG.

A bottom plate pad 52, which is a pad material having a high coefficient of friction, is installed at the tip end portion, which is the right end portion of the bottom plate 46, so as to give a constant load to the bottom paper P on the bottom plate 46. This makes it possible to prevent the bottommost paper P and the second paper from the bottom P from being double-fed.

However, if the force of the spring urging the bottom plate 46 is lower than the appropriate value, non-feeding occurs in which the paper P is not conveyed, and conversely, if it is higher than the appropriate value, double feeding occurs in which a large number of sheets P are conveyed. It ends up. Therefore, it is important to set the spring force in order to prevent non-feeding and double feeding.

The separation pad 48 made of the friction member shown in FIG. 4 is made of a material having a high coefficient of friction with respect to the paper (sheet), such as urethane foam rubber, EP (ethylene propylene) rubber, silicon rubber, cork, or a compounding material thereof. ing. As a result, the friction coefficient of the separation pad 48 is set higher than the friction coefficient between the sheets, and the difference in the friction coefficient prevents double feeding.

Further, in consideration of mass productivity, the separation pad 48 is formed into a rectangular shape in a simple shape in a plan view and a rectangular parallelepiped / plate shape in a stereoscopic view, and is attached and fixed to the cradle 49 using double-sided tape. The pedestal 49 swings in the vertical direction Z because the rotating shaft 49A of the pedestal provided on the downstream side of the sheet transport direction X is rotatably supported by the paper feed tray 30 within a predetermined angle range. It is possible.

A spring (compression spring) 55 is arranged on the lower side of the cradle 49. The cradle 49 and the separation pad 48 are urged substantially upward by the spring 55, that is, toward the center of rotation of the paper feed roller 47.

Here, the contact portion between the uppermost paper P placed on the bottom plate 46 and the paper feed roller 47 is designated as the paper feed nip N1, and the contact portion between the separation pad 48 and the paper feed roller 47 is designated as the separation nip N2. ..

Even if two sheets of paper P fed from the paper feed nip N1 overlap, they are separated into one sheet by applying a friction load by the separation pad 48 to the lower sheet P of the two sheets by the separation nip N2. It is said that it can be transported.

For the separation of the paper P, the friction coefficient between the paper feed roller 47 and the paper P is μr, the friction coefficient between the paper Ps is μp, and the friction coefficient between the paper P and the separation pad 48 is μf. Due to the magnitude relationship (μr> μf> μp) of these three friction coefficients, only the best paper is friction-separated and fed.

As the material of the cradle 49, a resin material having a lower friction coefficient than the separation pad 48 and being inexpensive is selected and used in order to improve the transportability. On the upstream side of the separation pad 48, a convex front handling portion 49B formed integrally with the cradle 49 is formed. The height of the front handling portion 49B is set higher than the upstream end 48A of the separation pad 48 in order to prevent the tip of the paper P from being caught by the upstream end 48A of the separation pad 48.

The support structure of the pedestal 49 is not limited to the swingable support structure centered on the rotating shaft 49A as described above. The rotation shaft 49A can be arranged on the upstream side instead of the downstream side. Further, the pedestal 49 may be arranged so as to be linearly parallel to the rotation center direction of, for example, the paper feed roller 47, depending on the layout of parts around the pedestal 49 and the like.

(Embodiment 1)
The sheet feeding device 11 according to the first embodiment of the present invention will be described with reference to FIGS. 5 to 9. FIG. 5 is a perspective view showing a main part of the sheet feeding device 11 of the first embodiment, and FIG. 6 is a pedestal 49 and a separation pad 48 in a state where the paper feed roller 47 is removed from the sheet feeding device 11 of the first embodiment. FIG. 7 is a perspective view of the cradle 49 in a state where the paper feed roller 47 and the separation pad 48 are removed from the sheet feeding device 11 of the first embodiment. FIG. 8A is a schematic cross-sectional view showing a main part of the conventional sheet feeding device 110, and FIG. 8B is a schematic showing a main part of the sheet feeding device 11 of the first embodiment of the present invention. It is a sectional view.

As shown in FIG. 8B, the sheet feeding device 11 of the first embodiment has a sheet transporting direction X from the center N2P of the separation nip N2 as compared with the conventional sheet feeding device 110 of FIG. 8A. A protrusion 12 is provided in the width direction orthogonal to the sheet transport direction X on the holding surface of the separation pad 48 of the pedestal 49, and the protrusion 12 is provided with the upstream end of the sheet transport direction X in the protrusion 12 and the separation pad. The difference is that the space 13 is formed in the portion surrounded by the lower surface of the 48 and the upper surface of the cradle 49.

Also in the sheet feeding device 11 of the first embodiment, a separation pad 48, which is a friction member longer in the width direction Y than the paper feed roller 47, is attached and fixed to the cradle 49.
As shown in FIGS. 7 and 8 (b), the protruding portion 12 has a stepped shape protruding upward and a rectangular shape in a cross-sectional view, and is integrally formed with the cradle 49 (integrated with resin). It is molded). The protrusion 12 is formed so as to extend in the width direction and have substantially the same length as the separation nip.

As will be described in Examples described later, the protrusion 12 is configured and formed in FIG. 7 with a height H of the protrusion 12 of 0.3 mm and a length Lx of the protrusion 12 in the sheet transport direction X of 3 mm. This is the optimum condition to prevent the paper from turning over and jamming. These numerical values are target values, and when the tolerance is taken into consideration, the height is set to H = 0.3 ± 0.03 mm and the length is set to L = 3 ± 0.3 mm.
Expressed in consideration of the above tolerance, the height H of the protrusion 12 is approximately 0.3 mm, and the length Lx of the protrusion 12 in the sheet transport direction X is approximately 3 mm.

Here, before explaining the embodiment, the case of double feeding due to the friction coefficient of each paper will be described.
(1) Double feeding: Double feeding of two sheets (μr>μf> μp) → (μr>μp> μf) When the friction coefficient between the two sheets is large, double feeding is performed.
(2) When double-feeding: Double-feeding of a plurality of sheets (μr>μf>μp1> μp2): Separately feed the paper between μp1 and μp2.
Therefore, the simple friction separation method is affected by the variation in the coefficient of friction between the sheets, and therefore, in the case of an unfamiliar user who relies heavily on the user's operability, problems such as frequent double feeding occur. For the separation of the paper P, the friction coefficient between the paper feed roller 47 and the paper P is μr, the friction coefficient between the paper Ps is μp, and the friction coefficient between the paper P and the separation pad 48 is μf. Due to the magnitude relationship (μr>μf> μp) of these three friction coefficients, only the top paper is frictionally separated and fed.

With reference to FIG. 9, the sheet feeding device 11 of the first embodiment describes a separation operation when one sheet of paper is fed and a separation operation when two sheets of paper are double-fed. FIG. 9A is a schematic cross-sectional view illustrating the operation of the sheet feeding device 11 of the first embodiment when feeding one sheet of paper, and FIG. 9B is the sheet feeding device 11 of the first embodiment. It is a schematic cross-sectional view explaining the separation operation at the time of double feeding of two sheets of paper.
As described above, there is a protrusion 12 provided on the pedestal 49 under the separation pad 48, and a space 13 is formed between the separation pad 48 and the pedestal 49. When one sheet of paper P1 is conveyed, the tip P1a of the paper P1 is conveyed along the separation pad 48. At this time, since there is no force that regulates the tip P1a of the paper P1 (force that pushes the tip P1a in the vertical direction Z), the paper P1 is smoothly conveyed.

On the other hand, as shown in FIG. 9B, when the two sheets P1 and P2 are double-fed, the second sheet P2 is conveyed in close contact with the first sheet P1. Then, when the tip P2a of the second sheet P2 is further conveyed to the downstream side of the sheet conveying direction X while being in contact with the separation pad 48, the second sheet P2 cannot escape upward (paper on top). There is P1). Therefore, the second sheet of paper P2 is conveyed while deforming (deflecting) the separation pad 48 located above the space 13, and finally stops in the vicinity of the upstream end of the protrusion 12. Even when the three sheets P are double-fed and conveyed, the second and subsequent sheets are similarly stopped. At this time, a space 13 is formed between the separation pad 48 and the protrusion 12, and since the separation pad 48 itself is also an elastic body, it is pushed by the tip P2a of the second sheet P2 and deformed. P2 is stopped.

Based on the above configuration and operation by the seat feeding device 11 of the first embodiment, the example product and the conventional product (corresponding to the seat feeding device 110 of FIG. 8A) in which the seat feeding device 11 of the first embodiment is implemented. ), The details of the test results and the equipment used for the test are listed below. The details of the equipment and the like common in relation to the device example of FIG. 4 in the seat feeding device of the embodiment and the conventional product are as follows.

-Material of separation pad 48: Urethane foam rubber material-Material of cradle 49: Polycarbonate (PC)
-Material of paper feed roller 47: EPDM
-Diameter of paper feed roller 47: φ36 mm
-Transfer speed of paper feed roller 47: 60 mm / s
-Width of separation nip N2 (width of paper feed roller 47): 50 mm
-Reference value (1.0 times) of the pressing force (urging force) of the spring 55 that generates the separation nip N2: 3N
-Paper type: Plain paper (Axle Multi-Paper Super White A4) and replenished paper with a coefficient of friction different from this plain paper are used.-Paper entry angle: 30 °

FIG. 2 shows an embodiment product corresponding to the seat feeding device 11 and a conventional seat feeding device 110 corresponding to the seat feeding device 110 in which only the pressing force of the separation pressure spring is changed as follows. The test was carried out by mounting it on the color laser printer shown in.
Further, as described in FIG. 7, the specifications of the example product corresponding to the seat feeding device 11 of the first embodiment are that the height H of the protrusion 12 is 0.3 mm and the seat transport direction X of the protrusion 12 The one formed with a length Lx of 3 mm was used.

As the content of the test, a replenishment state (a state in which the friction coefficient of the paper was reduced) was created every five sheets, this was counted as one test, and the double feed occurrence rate during transportation was calculated and evaluated. The denominator of the test results below represents the number of tests, and the numerator represents the number of times double feeding has occurred.

Test result (effect confirmation result)
(1) Conventional product: Standard value of pressing force of separation pressure spring (1.0 times) Product: 10/10 occurrence (2) Conventional product: Pressure of separation pressure spring is 1.5 times product・ ・ ・ ・ ・ ・ 10/10 occurrence (3) Conventional product: Separation pressure spring pressing force is 2.0 times higher ・ ・ ・ ・ ・ ・ ・ ・ 10/10 occurrence (4) Example product: Separation Pressurized spring reference value (1.0 times) product: 0/10 not generated As described above, the conventional product with increased pressurization of the separate pressurizing spring had no effect of preventing double feeding. However, it was confirmed that in the example product to which the example of the first embodiment of the present invention was applied, no double feeding occurred and a remarkable effect was exhibited.

Here, the paper separation method will be supplemented. The paper transfer drive drives the paper to be conveyed by the paper feed roller. In the "friction separation method", the paper to be separated is stopped and separated by a friction member such as a separation pad. In the "edge separation method", the tip (edge) of the paper to be separated is touched to a bank or the like to stop and separate.
As described with reference to FIG. 9B, when the two sheets P1 and P2 are double-fed, the second sheet P2 is closely conveyed under the first sheet P1 and is conveyed. When the tip P2a of the first sheet P2 is further conveyed to the downstream side of the sheet conveying direction X while being in contact with the separation pad 48, the second sheet P2 cannot escape upward because the sheet P1 is on the upper side. .. When the paper is further conveyed in this state, the separation pad 48 is configured to be elastically deformable, so that the second sheet P2 is deformed (deflected) so as to press the separation pad 48 located above the space 13. It is transported while letting it. That is, in the present invention, by switching from friction separation to edge separation, the paper can be reliably separated and double feeding can be prevented.

As described above, according to the first embodiment and the above embodiment, the sheet feeding device and the image forming device having significantly improved separation performance even when using replenished paper or different types of paper which could not be separated in the past. Can be provided. In addition, since it can be realized by a simple configuration in which a protrusion is provided on the cradle and a space is formed along with the protrusion, the cost does not increase.

With the conventional friction separation method, it is difficult to separate papers with different friction coefficients (additional paper or different types of paper), so users are prohibited from using additional papers or different types of papers. It was dealt with by reducing the frictional force between the papers by handling. However, the problem was not solved because it was caused by user operation.
In the present invention, by configuring the friction member so that it can be deformed, edge separation is realized and the separation performance is remarkably improved. When the first sheet of paper is transported, the tip of the paper can escape above the separation pad, so that the tip of the paper is not caught by the friction member. Next, when the second sheet of paper (with the first sheet of paper on top) enters beyond the nip of the friction member, the conventional model exerts a force to stop the second sheet of paper. Because it was not there, it could not be separated, and it was transported, causing jams such as double feeding.

In the separated configuration of the sheet feeding device according to the present invention, since the second sheet of paper has the first sheet of paper on the top, the tip of the paper cannot escape upward. When the paper is further conveyed in this state, the separation pad is configured to be deformable, so the tip of the second sheet pushes the separation pad, the friction member is deformed (bent), and the paper stops. Be made to. That is, with the simple configuration described above, it is possible to separate the paper by switching from friction separation to edge separation.

The separated configuration of the sheet feeding device according to the present invention can be variously set in consideration of the above-mentioned technical matters. That is, the shape / dimension of the protrusion 12, the shape / dimension / material of the separation pad 48, and the type of paper to be used (thickness, friction coefficient, etc.) are set as parameters, and the separation pad 48 and the cradle 49 are set. It can be said that the space 13 having an appropriate size may be formed between the protrusion 12 and the friction portion 12 and the edge separation may be switched to the edge separation.

Reference to the prior art document related to the present invention, the above-mentioned Patent Document 1 has a configuration in which protrusions are provided on both sides of the pedestal holding the bottom separation pad (at a position outside the separation pad) to improve the separation performance. It is disclosed. However, when papers having significantly different frictional forces between the papers are used, the paper separation performance cannot be expected to be improved by the protrusions, and as a result, the problem of poor separation cannot be solved.

Further, Japanese Patent No. 2991816 discloses a configuration in which a pad support member of a separation pad is wound around a paper feed roller (there is no friction member in the wound portion) to improve separation performance. However, in the patent, there is no space formed between the friction member and the pedestal as in the present invention, and the friction separation is not switched to the edge separation.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and the present invention described in the claims unless otherwise specified in the above description. Various modifications and changes are possible within the scope of the above. For example, the technical items described in the above-described embodiments and examples may be appropriately combined.

For example, the protrusion is not limited to being integrally formed with the pedestal as described above, but may be formed separately from the pedestal. Specifically, as the protrusions, for example, several Mylar plate materials formed of PET may be laminated on a table so as to be overlapped with each other in a stepped manner.

The effects appropriately described in the embodiments of the present invention merely list the most preferable effects arising from the present invention, and the effects according to the present invention are limited to those described in the embodiments of the present invention. It's not a thing.

1: Process unit 11: Sheet feeding device (seat feeding means)
12: Protrusion 13: Space 30: Paper tray 31: Paper path (example of transport path)
37: Paper ejection roller pair (example of ejection means) 46: Bottom plate 47: Paper feed roller (example of rotary feeding member) 48: Separation pad (example of friction member)
48A: Upstream end 49: Cradle 49A: Rotating shaft 49B: Front handling part 50: Paper feed roller shaft 51: Bottom plate rotating shaft 52: Bottom plate pad 55: Spring N1: Paper feed nip N2: Separation nip N2P: Separation nip Center P: Paper (an example of a sheet)

JP 2015-189561

Claims (11)

A rotary feeding member that comes into contact with one surface of the sheet and feeds the sheet downstream along a predetermined transport path.
A friction member which is arranged at a position facing the rotary feed member and sandwiching the transport path and which contacts the rotary feed member to form a separation nip.
A cradle that holds the friction member on the side opposite to the separation nip,
In the seat feeding device equipped with
A downstream side in the sheet conveyance direction than the separation nip, the cradle of the protrusions in the width direction orthogonal to the sheet conveying direction of the holding surface of the friction member is provided Rutotomoni, the holding surface and said protrusion The pedestal on the downstream side in the sheet transport direction from the protrusion has a step in order, and a space is formed in a portion surrounded by the protrusion, the friction member, and the holding surface of the pedestal.
The protrusion is provided with substantially the same length as the separation nip, at a constant height over the width direction and at a constant length in the sheet transport direction , and the space is substantially the same as the separation nip. It is formed at a constant height over the width direction in length.
When there are a plurality of sheets passing through the separation nip, the first sheet of the plurality of sheets in contact with the rotary feeding member is smoothly conveyed. A sheet feeding device configured such that the tips of the plurality of remaining sheets excluding the eye sheet stop while deforming the friction member . In the sheet feeding device according to claim 1,
A sheet feeding device characterized in that a front handling portion is provided on the upstream side in the sheet transport direction with respect to the separation nip of the cradle. In the sheet feeding device according to claim 2,
A sheet feeding device characterized in that the upper end portion of the front handling portion is located closer to the rotary feeding member side than the upper end portion of the friction member. In the sheet feeding device according to any one of claims 1 to 3,
A sheet feeding device characterized in that the height of the protrusion is approximately 0.3 mm and the length of the protrusion in the sheet transport direction is approximately 3 mm . In the sheet feeding device according to any one of claims 1 to 4.
A sheet feeding device characterized in that the protrusions extend in the width direction to a predetermined length . In the sheet feeding device according to any one of claims 1 to 5,
The sheet feeding device is characterized in that the protrusion is integrally formed with the cradle . In the sheet feeding device according to any one of claims 1 to 6,
A sheet feeding device characterized in that the protrusion is formed separately from the cradle. In the sheet feeding device according to any one of claims 1 to 7 .
The friction member is a sheet feeding device characterized in that the friction member is made of a material that elastically deforms when at least two sheets are double-fed and passes through the separation nip . Sheet feeding means for feeding sheets and
An image-forming means for forming an image on the fed sheet,
Discharge means for discharging the sheet on which the image is formed, and
In an image forming apparatus equipped with at least
An image forming apparatus according to any one of claims 1 to 8, wherein the sheet feeding device is used as the sheet feeding means . A sheet feeding means for feeding a sheet on which an image to be read is formed , and
A reading means for reading the image on the fed sheet ,
Discharge means to eject the sheet after reading ,
In an image reader equipped with at least
An image reading device according to any one of claims 1 to 8 , wherein the sheet feeding device is used as the sheet feeding means . The image forming apparatus according to claim 9, wherein the image forming apparatus is a multifunction device in which at least two or more of a copying machine, a facsimile, a printer, a printing machine, an inkjet recording device, and an image reading device are combined .

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