JP2006199397A - Paper feeding device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent overlapping feeding of paper not largely depending on a handling member arranged at a latter stage by not simply conveying the paper stored in a paper feed cassette by a conventionally existing first pickup roller but by performing paper feeding by the first pickup roller after a slight air layer is formed between the paper sheets by a second pickup roller. <P>SOLUTION: The paper feeding device is provided with a pair of pickup rollers 71a, 71b arranged in a left/right direction X and deflecting/curving the paper P stored in the paper feed cassette 33 in the left/right direction X. The conventional first pickup rollers 51a, 51b are brought into contact with the paper P and convey it in a paper conveying direction Y after the paper P is curved in the left/right direction X by the second pickup rollers 71a, 71b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet feeding device including a conveying unit that conveys a sheet of paper stored in a sheet feeding cassette one by one from the top by pickup rollers arranged in the left and right direction perpendicular to the sheet conveying direction, and this The present invention relates to an image forming apparatus equipped with a paper feeding device.

  The sheets stored in the image forming apparatus are selectively conveyed one by one from the top by the pickup roller, and are conveyed to the printing unit via the sheet conveyance path.

  FIG. 11 shows the relationship between a conventional pickup roller and a paper feed cassette. 12A is a cross-sectional view taken along line A2-A2 of FIG. 11, and FIG. 12B is a cross-sectional view taken along line B2-B2 of FIG.

  As shown in FIG. 11, side guides 161 and 161 and a rear end guide 162 that are movable according to the size of the stored paper are arranged in the paper feed cassette 133, and the paper feed cassette 133 is transported. Cassette claws 163 and 163 that respectively hold the left and right corners on the leading edge side of the stored paper are disposed at the left and right corners of the downstream leading edge. The paper stored in the paper feed cassette 133 is held by the cassette claws 163 and 163 so that the leading end side does not come off unexpectedly, and a certain amount of conveying force is given to the paper by the pair of left and right pickup rollers 151 and 151. Then, the leading edge of the sheet is easily detached from the cassette claws 163 and 163 by the bending force of the sheet itself. Although not shown, a holding member is provided on the bottom surface of the paper cassette 133 to hold the stored paper in a state where it is always lifted upward.

  In this case, in the conventional sheet feeding device, the shapes and arrangement structures of the pickup rollers 151 and 151 are set so that the timing of contact of the pickup rollers 151 and 151 with the uppermost sheet and the timing of separation from the sheet are the same. By setting, it is considered that the sheet does not tilt at the start of sheet conveyance, that is, is not conveyed obliquely.

  According to such a configuration, both pickup rollers 151 and 151 are simultaneously brought into contact with the uppermost sheet of the paper feed cassette 133 at the start of paper conveyance, and are conveyed evenly on the left and right by the rotation of both pickup rollers 151 and 151. Become. Therefore, until the leading edge of the sheet passes over the cassette claws 163 and 163, as shown in FIGS. 12A and 12B, the left and right sides of the sheet between the pickup rollers 151 and 151 and the cassette claws 163 and 163 are left and right. An even shape of bending will occur. Such simple bending of the left and right uniform shapes does not separate when a plurality of sheets have a strong electrostatic attraction force, and this is one factor in the occurrence of double feeding called “W feed”. It was.

  In addition, the sheets stored in the sheet cassette are electrostatically attracted between the sheets stored by such a sheet feeding process, the environmental conditions of the apparatus, and the sheet feeding pressure of the pickup roller depending on the type of sheets stored. The power is different. When the paper in such a state is selectively conveyed one by one by the pickup roller, a double feed phenomenon occurs as described above, the paper jam in the conveyance path, the leading edge of the print image is uneven, and the conveyance roller in the conveyance path is damaged. And so on.

For this reason, in the conventional paper feeder, a paper feed member for preventing W feed is disposed between the paper feed cassette and the printing means, and the conveyed paper is rubbed with the paper pressure of the paper feed member. Thus, double feeding is prevented (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 2004-196538

  However, when the papers are rubbed together with the paper pressure generated by the paper paper member as in Patent Document 1, a partial increase in electrostatic capacity may be caused on the paper to be conveyed. Such a partial increase in electrostatic capacity is caused when the image information (toner image) on the photosensitive member is transferred to the paper in the transfer process of the printing unit, and between other low electrostatic capacity parts on the paper. There is a problem in that the toner transfer efficiency is different and the print quality is deteriorated. Further, since the paper is rubbed, impurities in the paper (usually referred to as “paper dust”) are deposited, and this paper portion adheres to the printing means, the conveyance roller, etc., resulting in a decrease in print quality. There was also.

  The present invention was devised to solve such problems, and its purpose is not to simply convey the paper stored in the paper feed cassette by the conventional first pickup roller, but by the second pickup roller. After a slight air layer is formed between the sheets, the sheet is conveyed by the first pick-up roller, so that the sheet feeding can be prevented without largely depending on the rear member disposed in the subsequent stage. An object of the present invention is to provide a paper device and an image forming apparatus equipped with the paper feeding device.

  In order to solve the above-described problem, a paper feeding device according to the present invention is configured to feed sheets stored in a sheet feeding cassette one sheet at a time from the top by a first pickup roller disposed in the left-right direction orthogonal to the sheet conveyance direction. A second pickup roller that is arranged in a pair in the left-right direction and bends and curls a sheet stored in a sheet feed cassette in the left-right direction, in the sheet feeding device including a transport unit that transports in the transport direction. It is characterized by having.

  In this case, the timing of contact of each pickup roller with the sheet so that the first pickup roller bends the sheet in the left-right direction by the second pickup roller and then contacts the sheet and conveys it in the sheet conveyance direction. Set. In addition, the rotation direction of the paired second pickup rollers is the reverse rotation direction. Specifically, the rotation direction of the second pickup roller is set to a direction in which the sheet is curved between the paired second pickup rollers.

  With such a configuration, before the sheet is conveyed by the first pickup roller, the sheet is bent left and right by the second pickup roller to separate the uppermost sheet from the sheet below it. In the meantime, an air layer can be formed. Or even if it does not go to isolation | separation, the adsorption | suction force by the static electricity between the uppermost sheet | seat and the sheet | seat under it can be weakened. As a result, even if the sheet is simply picked up by the first pickup roller as before, the uppermost sheet and the sheet below can be easily separated, and the occurrence of double feed can be avoided more reliably. It becomes possible.

  In this case, a sheet leading edge pressing plate for holding the left and right corners on the leading end side of the stored sheet is disposed at the left and right corners of the conveying downstream end of the sheet feeding cassette, and the second pickup The distance by which the sheet is bent in the left-right direction by the roller is a distance at which the left and right end corners of the sheet do not come off the sheet end pressing plate. Thus, the sheet bent and bent in the left-right direction is conveyed in the conveyance direction by the first pickup roller, so that the sheet between the first pickup roller and the sheet front end pressing plate is now along the left-right direction. Therefore, the separation between the uppermost sheet and the underlying sheet is further promoted. For this reason, when the left and right leading edge corners of the paper slip over the paper leading edge pressing plate, the uppermost paper and the paper underneath are reliably separated, and the pressure of the paper backing member at the rear stage is reduced by the conventional pressure. It becomes possible to make it lower than the thing. For this reason, it is possible to suppress a partial increase in static electricity of the conveyed paper. Furthermore, it is possible to remove the paper sheet member from the apparatus.

  Here, the first and second pickup rollers may be configured to rotate by driving from the same driving source. This eliminates the need for a new drive source and makes it possible to suppress the increase in size and manufacturing cost of the device as much as possible.

  Further, the second pickup roller may be provided so as to be capable of reciprocating in the left-right direction orthogonal to the paper transport direction. In this way, by allowing reciprocal movement in the left-right direction, the contact position of the second pickup roller with respect to the paper according to the type of paper stored in the paper feed cassette is set to an optimal position for forming a curve. It becomes possible to adjust.

  Furthermore, by mounting the paper feeding device having the above-described configuration in the image forming apparatus, it is possible to provide an image forming apparatus in which the occurrence of double feeding itself and the occurrence of troubles due to double feeding are reduced.

  According to the present invention, before the sheet is conveyed by the first pickup roller, the sheet is bent left and right by the second pickup roller, so that the uppermost sheet and the sheet below the upper sheet are separated from each other. An air layer can be formed, or the adsorption force due to static electricity between the uppermost sheet and the sheet below it can be weakened even if separation is not required. Even if the paper is simply picked up, the uppermost paper and the paper below it can be easily separated. Thereby, since the occurrence of double feeding can be avoided more reliably, it is possible to more reliably prevent the occurrence of printing failure and jamming due to double feeding.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the present embodiment, a case will be described in which the paper feeding device of the present invention is applied to a multifunction peripheral which is an example of an image forming apparatus.

-Description of overall configuration of MFP-
FIG. 1 schematically shows an internal configuration of a multifunction machine 1 as an image forming apparatus according to the present embodiment. The multifunction device 1 has a copier mode, a printer mode, and a FAX mode as image forming modes for forming an image on a sheet (including a recording medium such as an OHP), and each mode is selected by a user.

  The multifunction machine 1 includes a scanner unit 2 as an original reading unit, an image forming unit 3, and an automatic document feeder 4. Hereinafter, each part will be described.

<Description of Scanner Unit 2>
The scanner unit 2 reads image of a document placed on a document table 41 made of transparent glass or the like, or a document image fed one by one by the document automatic sheet feeding unit 4 to generate image data. It is. The scanner unit 2 includes an exposure light source 21, a plurality of reflecting mirrors 22, 23, 24, an imaging lens 25, and a photoelectric conversion device (CCD: Charge Coupled Device) 26.

  The exposure light source 21 emits light to a document placed on the document table 41 of the automatic document feeder 4 or a document conveyed through the automatic document feeder 4. Each reflecting mirror 22, 23, 24 reflects the reflected light from the document once in the left direction in the drawing, as shown by an alternate long and short dash line A in FIG. Reflected in the right direction in the figure so as to go to 25.

  As a document image reading operation, when a document is placed on the document table 41 (when used as a “sheet fixing method”), the exposure light source 21 and the reflecting mirrors 22, 23, 24 are connected to the document table 41. The image of the entire document is read by scanning in the horizontal direction. On the other hand, when reading a document conveyed by the automatic document feeder 4 (when used as a “sheet moving method”), the exposure light source 21 and the reflecting mirrors 22, 23, 24 are fixed at the positions shown in FIG. Then, the image is read when the document passes through a document reading unit 42 of the automatic document feeder 4 described later.

  The light reflected by the reflecting mirrors 22, 23, 24 and passing through the imaging lens 25 is guided to the photoelectric conversion element 26, and the reflected light is converted into an electric signal (original image data) by the photoelectric conversion element 26. It is like that.

<Description of Image Forming Unit 3>
The image forming unit 3 includes an image forming system 31 and a paper transport system 32.

  The image forming system 31 includes a laser scanning unit 31a and a photosensitive drum 31b as a drum-type image carrier. The laser scanning unit 31a irradiates the surface of the photosensitive drum 31b with laser light based on the document image data converted by the photoelectric conversion element 26. The photosensitive drum 31b rotates in a direction indicated by an arrow in FIG. 1, and an electrostatic latent image is formed on the surface of the photosensitive drum 31b by being irradiated with laser light from the laser scanning unit 31a.

  In addition to the laser scanning unit 31a, a developing device (developing mechanism) 31c, a transfer unit (transfer mechanism) 31d, a cleaning device (cleaning mechanism) 31e, a static eliminator (not shown), Charging units 31f are sequentially arranged in the circumferential direction. The developing device 31c develops the electrostatic latent image formed on the surface of the photosensitive drum 31b into a visible image with toner (visualizing substance). The transfer unit 31d transfers a toner image formed on the surface of the photosensitive drum 31b onto a sheet as a recording medium. The cleaning device 31e removes the toner remaining on the surface of the photosensitive drum 31b after the toner transfer. The static eliminator removes residual charges on the surface of the photosensitive drum 31b. The charging unit 31f charges the surface of the photosensitive drum 31b before the electrostatic latent image is formed to a predetermined potential.

  For this reason, when an image is formed on a sheet, the surface of the photosensitive drum 31b is charged to a predetermined potential by the charging unit 31f, and the laser scanning unit 31a emits laser light based on the original image data on the photosensitive drum 31b. Irradiate the surface. Thereafter, the developing device 31c develops a visible image with toner on the surface of the photosensitive drum 31b, and the toner image is transferred onto a sheet by the transfer unit 31d. Further, after that, the toner remaining on the surface of the photosensitive drum 31b is removed by the cleaning device 31e, and the residual charge on the surface of the photosensitive drum 31b is removed by the static eliminator. Thereby, one cycle of the image forming operation (printing operation) on the paper is completed. By repeating this cycle, it is possible to continuously form images on a plurality of sheets.

  On the other hand, the paper transport system 32 transports the paper stored in the paper feed cassette 33 as the paper storage unit or the paper placed on the manual feed tray 34 one by one to form an image by the image forming system 31. At the same time, the image-formed paper is discharged to a paper discharge tray 35 as a paper discharge portion.

  The paper transport system 32 includes a main transport path 36 and a reverse transport path 37. One end side of the main conveyance path 36 is branched into two, one branch end faces the discharge side of the paper feed cassette 33 and the other branch end faces the discharge side of the manual feed tray 34. ing. The other end of the main transport path 36 faces the paper discharge tray 35. One end of the reverse conveyance path 37 is connected to the main conveyance path 36 on the upstream side (lower side in the drawing) of the transfer unit 31d, and the other end is downstream of the transfer unit 31d. (Upper side in the figure) is connected to the main transport path 36.

  A first pickup roller 51 having a half-moon cross section is disposed at one branch end of the main conveyance path 36 (a portion facing the discharge side of the paper feed cassette 33). By the rotation of the first pickup roller 51, the sheets stored in the sheet feeding cassette 33 can be intermittently fed to the main transport path 36 one by one. Although not shown in the drawings, actually, the second pickup roller 71 according to the present invention is disposed in addition to the first pickup roller 51. The second pickup roller 71 will be described in detail later. Describe. Similarly, a pick-up roller 36b having a half-moon cross section is disposed at the other branch end of the main conveyance path 36 (a portion facing the discharge side of the manual feed tray 34). With the rotation of the pickup roller 36b, the sheets placed on the manual feed cassette 34 can be intermittently fed to the main transport path 36 one by one.

  A registration roller 36d is disposed upstream of the position where the transfer unit 31d is disposed in the main transport path 36. The registration roller 36d conveys the sheet while aligning the toner image on the surface of the photosensitive drum 31b with the sheet.

  A fixing device 39 including a pair of fixing rollers 39a and 39b for fixing the toner image transferred onto the sheet by heating is disposed downstream of the position where the transfer unit 31d is disposed in the main conveyance path 36. ing. Further, a discharge roller 36 e for discharging the paper to the paper discharge tray 35 is disposed at the downstream end of the main transport path 36.

  A branching claw 38 is disposed at a connection position at the upstream end of the reverse conveyance path 37 with respect to the main conveyance path 36. The branch claw 38 is rotated about the horizontal axis between the first position indicated by the solid line in FIG. 1 and the second position that rotates counterclockwise from the first position to open the reverse conveyance path 37. It is free to rotate. When the branch claw 38 is in the first position, the paper is conveyed toward the paper discharge tray 35, and when it is in the second position, the paper can be supplied to the reverse conveyance path 37. The reverse conveyance path 37 is provided with a conveyance roller 37a. When the paper is supplied to the reverse conveyance path 37 (when the paper is supplied to the reverse conveyance path 37 by so-called switchback conveyance), this conveyance is performed. The sheet is conveyed by the roller 37a, and the sheet is reversed on the upstream side of the registration roller 36d and is conveyed again through the main conveyance path 36 toward the transfer unit 31d. That is, an image can be formed on the back side of the paper.

  In the image forming unit 3 having the above-described configuration, the sheet feeding cassette 33, the manual feed tray 34, the pickup rollers 51 and 36b, and the registration roller 36d are also referred to as a sheet feeding unit hereinafter.

<Description of Automatic Document Feeder 4>
Next, the automatic document feeder 4 will be described. The automatic document feeder 4 is configured as a so-called automatic duplex document feeder. The automatic document feeder 4 can be used as a sheet moving type, and includes a document tray 43 as an original placement unit, an intermediate tray 44, a document discharge tray 45 as a document discharge unit, and trays 43, 44, A document transport system 46 is provided for transporting a document between 45.

  The document transport system 46 includes a main transport path 47 for transporting a document placed on the document tray 43 to the intermediate tray 44 or the document discharge tray 45 via the document reading unit 42, and the document on the intermediate tray 44. And a sub-transport path 48 for supplying the main transport path 47 to the main transport path 47.

  A document pick-up roller 47a and a separating roller 47b are disposed at the upstream end of the main conveyance path 47 (a portion facing the discharge side of the document tray 43). A separation plate 47c is disposed below the separation roller 47b, and one of the documents on the document tray 43 is placed between the separation roller 47b and the separation plate 47c as the document pickup roller 47a rotates. Is fed to the main transport path 47. PS rollers 47e and 47e are disposed on the downstream side of the joining portion (B portion in the figure) of the main transport path 47 and the sub transport path 48. The PS rollers 47 e and 47 e adjust the leading edge of the document and the image reading timing of the scanner unit 2 and supply the document to the document reading unit 42. That is, the PS rollers 47e and 47e temporarily stop the conveyance of the document while the document is supplied, and adjust the timing to supply the document to the document reading unit 42.

  The document reading unit 42 includes a platen glass 42a and a document pressing plate 42b. When the document supplied from the PS rollers 47e and 47e passes between the platen glass 42a and the document pressing plate 42b, the exposure light source 21 is provided. Is irradiated to the original through the platen glass 42a. At this time, the document image data is acquired by the scanner unit 2. A biasing force by a coil spring (not shown) is applied to the back surface (upper surface) of the document pressing plate 42b. Thereby, the document pressing plate 42b is in contact with the platen glass 42a with a predetermined pressing force, and prevents the document from floating from the platen glass 42a when passing the document reading unit 42.

  On the downstream side of the platen glass 42a, a conveyance roller 47f and a document discharge roller 47g are provided. The document that has passed over the platen glass 42a is discharged to the intermediate tray 44 or the document discharge tray 45 through the transport roller 47f and the document discharge roller 47g.

  An intermediate tray swinging plate 44 a is disposed between the document discharge roller 47 g and the intermediate tray 44. The intermediate tray swinging plate 44a swings between a position 1 indicated by a solid line in the figure and a position 2 that is flipped upward from the position 1 with the end on the intermediate tray 44 side being the center of swinging. It is possible. When the intermediate tray swinging plate 44 a is at position 2, the document discharged from the document discharge roller 47 g is collected to the document discharge tray 45. On the other hand, when the intermediate tray swinging plate 44a is at the position 1, the document discharged from the document discharge roller 47g is discharged to the intermediate tray 44. When the sheet is discharged onto the intermediate tray 44, the edge of the document is sandwiched between the document discharge rollers 47g and 47g. It is supplied to the transport path 48 and is sent again to the main transport path 47 via the sub-transport path 48. The reverse rotation operation of the document discharge roller 47g is performed by adjusting the document delivery to the main conveyance path 47 and the image reading timing. Thus, the image on the back side of the document is read by the document reading unit 42.

-Basic operation of MFP-
As an operation of the multi-function device 1 configured as described above, first, when the multi-function device 1 functions as a printer (printer mode), print data (image data or text) transmitted from a host device such as a personal computer is used. Data), and the received print data (print data) is temporarily stored in a buffer (memory) (not shown). Along with storing the print data in the buffer, the print data is sequentially read from the buffer, and based on the read print data, an image is formed on the sheet by the image forming operation of the image forming unit 3 described above.

  When the multifunction machine 1 functions as a scanner (FAX mode), the scanned image data of the document read by the scanner unit 2 is temporarily stored in a buffer. Along with storing the scan image data in the buffer, the scan image data is sequentially transmitted from the buffer to the host device, and the image is displayed on the display or the like of the host device.

  Further, when the multifunction device 1 functions as a copier (copier mode), an image is formed on a sheet by the image forming operation of the image forming unit 3 based on the original image data read by the scanner function. .

  Here, the copier mode will be described in more detail.

-Explanation of image forming operation in copier mode-
When copying an image of a document on a sheet in the copier mode, after placing the document to be copied on the document table 41 or the document tray 43 of the scanner unit 2, each input key provided on an operation panel unit (not shown) is pressed. Input settings such as the number of prints and print magnification, and press a start key (not shown) to start the copy operation.

  When the start key is pressed, in the multifunction device 1, the pickup roller 51 or 36 b rotates to feed the paper from the paper feed cassette 33 or the manual feed tray 34 to the main transport path 36. The fed paper is transported to a registration roller 36d provided on the main transport path 36. The leading end in the conveyance direction of the sheet conveyed to the registration roller 36d is aligned with the toner image formed on the photosensitive drum 31b to be transferred to the sheet, so that the sub-scanning direction of the sheet and the registration roller 36d are aligned. It is chucked by the registration roller 36d so that its axial direction is parallel.

  The image data read by the scanner unit 2 is subjected to image processing under conditions input using an input key or the like, and is then transmitted as print data to a laser scanning unit (LSU) 31a. The LSU 31a forms an electrostatic latent image by irradiating the surface of the photosensitive drum 31b charged to a predetermined potential by the charger 31f with laser light based on the image data via a polygon mirror and various lenses (not shown). .

  After that, the toner adhering to the surface of the MG roller facing the photosensitive drum 31b provided in the developing tank (not shown) of the developing device 31c corresponds to the potential gap on the surface of the photosensitive drum 31b. The electrostatic latent image is visualized by attracting and adhering to the surface. The toner remaining on the photosensitive drum 31b is scraped off by a cleaning blade of a drum unit (not shown) and collected by a cleaner unit (not shown).

  Next, the registration roller 36d aligns the position of the sheet chucked by the registration roller 36d and the toner image formed on the surface of the photosensitive drum 31b (the timing is adjusted), and transfers the sheet to the photosensitive drum 31b. It is transported between the unit 31d. Next, the toner image on the surface of the photosensitive drum 31b is transferred onto the sheet using a transfer roller (not shown) provided in the transfer unit 31d.

  The sheet on which the toner image has been transferred passes between the fixing rollers 39a and 39b of the fixing device 39, so that heat and pressure are applied and the toner image is melted and fixed, and is discharged to the discharge tray 35 by the discharge roller 36e. Is done.

<Description Related to Second Pickup Roller 52 According to the Present Invention>
FIG. 2 is a schematic plan view of the paper feed cassette 33 in which the first pickup roller 51 and the second pickup roller 71 are arranged as viewed from above. FIG. 3 is a diagram in which the first pickup roller 51 and the second pickup roller 71 are arranged. 4 is a schematic perspective view of the sheet feeding cassette 33 as viewed obliquely from above, FIG. 4 is an enlarged front view of the first pickup roller 51 and the second pickup roller 71, and FIG. 5 is the first pickup roller. It is explanatory drawing which shows the structure of the rotation mechanism of 51 and the 2nd pick-up roller 71. FIG.

  That is, the first pick-up roller 51 (51a, 51b) is in the left-right direction (X direction in FIG. 2) orthogonal to the paper transport direction (Y direction in FIG. 2) at a position above the paper feed cassette 33. A plurality of sheets (a pair of left and right in the present embodiment) are arranged at a predetermined interval with respect to the arranged rotating shaft 52, and one sheet P stored in the sheet feeding cassette 33 is placed from the top. They are transported one by one.

  On the other hand, side guides 91 and 91 and a rear end guide 92 that are movable according to the size of the paper P to be stored are disposed in the paper feed cassette 33, and the transport downstream side front end portion of the paper feed cassette 33. At both left and right corners, cassette claws (sheet leading edge pressing plates) 93 and 93 for holding the left and right corners on the leading edge side of the stored paper P are disposed. The paper P stored in the paper feed cassette 33 is held by the cassette claws 93 and 93 so that the leading end of the paper P does not come off unexpectedly, and a conveyance force is given to the paper P by the first pickup rollers 51a and 51b. The leading end of the sheet is easily detached from the cassette claws 93 and 93 by the bending force of the sheet itself. Although not shown, a holding member is provided on the bottom surface of the paper cassette 33 to hold the stored paper P in a state where it is always lifted upward.

  Further, the second pickup roller 71 (71a, 71b) is a pair of rotary shafts 72a, 72b disposed at a predetermined interval in the paper transport direction (Y direction) above the paper feed cassette 33, respectively. The sheet P stored in the sheet feeding cassette 33 is bent in the left-right direction X and curved.

  Here, a structure for attaching the second pickup roller 71a to the rotating shaft 72a will be described.

  The second pickup roller 71a is supported in a state in which the support shaft 73a is rotatably inserted in insertion holes 74a and 74a formed on the distal end side of the pair of arm rods 74 and 74 arranged in the front-rear direction. ing. The arm rods 74 and 74 are supported rotatably with respect to the rotation shaft 72a in a state where the rotation shaft 72a is inserted into insertion holes 74b and 74b formed on the base end side.

  Further, an idle gear 64b is rotatably supported at the center of the outer surface of one arm rod 74, and a drive gear 64a is provided at the tip of the rotating shaft 72a protruding from the one arm rod 74. It is fixed. Further, a driven gear 64c is fixed to the tip of the support shaft 73a of the second pickup roller 71a protruding from one arm 74, and these drive gear 64a, idle gear 64b, and driven gear 64c are sequentially meshed. It is in a state. Here, the drive gear 64a, the idle gear 64b, and the driven gear 64c form planetary gear trains having different gear ratios. For example, the rotation shaft 72a moves to the left (in FIG. 3) due to the gear ratio. When rotating in the direction of the arrow R1, the entire armband 74, 74 rotates in the same direction (the direction of the arrow R1 in FIG. 3).

  In addition, a torsion coil spring 76 is fitted on the rotating shaft 72a, and one end 76a of the torsion coil spring 76 is bent into an L shape and is inserted and locked in a small hole formed in the arm rod 74. . On the other hand, the other end 76b is locked to a ceiling surface in the apparatus main body (not shown). The armband 74 is urged so as to be always pulled upward by the elastic action of the torsion coil spring 76. That is, the arm 74 is always pulled upward unless a rotational force is applied to the rotating shaft 72 a, and does not come into contact with the paper P stored in the paper feed cassette 33.

  Next, a structure for attaching the second pickup roller 71b to the rotating shaft 72b will be described.

  The second pickup roller 71b is supported in a state in which the support shaft 73b is rotatably inserted into insertion holes 74a and 74a formed on the distal end side of the pair of arm rods 74 and 74 arranged in the front-rear direction. ing. The arm rods 74 and 74 are supported rotatably with respect to the rotation shaft 72b in a state where the rotation shaft 72b is inserted into insertion holes 74b and 74b formed on the base end side.

  An idle gear 64b is rotatably supported at the center of the outer surface of one arm rod 74, and a drive gear 64a is provided at the tip of the rotating shaft 72b protruding from the one arm rod 74. It is fixed. Further, a driven gear 64c is fixed to the tip of the support shaft 73b of the second pickup roller 71b protruding from one arm rod 74, and the drive gear 64a, the idle gear 64b, and the driven gear 64c are sequentially meshed. It is in a state. Here, the drive gear 64a, the idle gear 64b, and the driven gear 64c form planetary gear trains having different gear ratios. For example, the rotation shaft 72a is directed in the right direction (in FIG. 3). When rotating in the direction of the arrow R2, the entire arm rods 74 and 74 are rotated in the same direction (the direction of the arrow R2 in FIG. 3).

  Further, a torsion coil spring 76 is fitted on the rotating shaft 72b, and one end 76a of the torsion coil spring 76 is bent into an L shape and is inserted and locked in a small hole formed in the arm rod 74. . On the other hand, the other end 76b is locked to a ceiling surface in the apparatus main body (not shown). The armband 74 is urged so as to be always pulled upward by the elastic action of the torsion coil spring 76. In other words, the arm 74 is in a state where it is always pulled upward unless a rotational force is applied to the rotary shaft 72 b, and does not come into contact with the paper P stored in the paper feed cassette 33.

  The second pick-up rollers 71a and 71b and the first pick-up rollers 51a and 51b having the above-described configuration are individually separated by a single drive source 99 as shown in FIG. The drive is controlled.

  That is, a rotary shaft gear 53 is fixed to the rotary shaft 52 of the first pickup rollers 51 a and 51 b, and this rotary shaft gear 53 is connected to the drive shaft 99 a of the drive source 99 via the intermediate gear 54. It is meshed with a fixed drive gear 98.

  The drive gear 98 is engaged with a first gear 61a for transmitting rotational force to the second pickup rollers 71a and 71b, and the second gear 61b is engaged with the first gear 61a. A bevel gear 62a is integrally fixed to one side surface of the second gear 61b, and the bevel gear 62a is fixed to one side surface of a third gear 61c arranged so as to be orthogonal to the second gear 61b. It meshes with the other bevel gear 62b fixed integrally. That is, the rotational force of the second gear 61b is transmitted to the third gear 61c by these bevel gears 62a and 62b. The rotating shaft of the second gear 61b is connected to a solenoid 95, and the bevel gears 62a and 62b can be engaged / released by on / off control of the solenoid 95. For example, when the solenoid 95 is off, the drive rod of the solenoid 95 moves in the direction V1 in FIG. 5 to disengage the bevel gears 62a and 62b. When the solenoid 95 is on, the drive rod of the solenoid 95 is The bevel gears 62a and 62b may be engaged with each other by moving in the V2 direction in FIG. However, on / off of the solenoid 95 and engagement / disengagement of the bevel gears 62a, 62b may be reversed.

  The third gear 61c is meshed with a sixth gear 61f fixed to the rotation shaft 72b of one second pickup roller 71b via a fourth gear 61d and a fifth gear 61e.

  Further, the fifth gear 61e is sequentially engaged with the seventh gear 61g and the eighth gear 61h via the first drive belt 61m, and the eighth gear 61h is connected to the ninth gear via the second drive belt 61n. It meshes with the gear 61i. The ninth gear 61i is meshed with a tenth gear 61j fixed to the rotation shaft 72a of the other second pickup roller 71a.

  The first to tenth gears 61a to 61j are attached to an inner wall surface (not shown) of the apparatus main body in which the paper feed cassette 33 is accommodated. Further, the rotation mechanism structure shown in FIG. 5 is merely an example, and the number of gears, the number of drive belts, and the combination thereof are not limited thereto. In FIG. 5, the number of drive sources 99 is one, but the drive sources of the first pickup rollers 51a and 51b and the drive sources of the second pickup rollers 71a and 71b can be provided separately.

  Due to the linked structure of the first to tenth gears 61a to 61j and the drive belts 61m and 61n, the rotation shaft 72a of the second pickup roller 71a and the rotation shaft 72b of the second pickup roller 71b are simultaneously and opposite to each other. Accordingly, the arm rod 74 that supports the second pickup roller 71a rotates in the direction of the arrow R1 in FIG. 3 against the urging force of the torsion coil spring 76, and the second pickup roller 71b. 3 is rotated in the direction of the arrow R2 in FIG. 3 against the urging force of the torsion coil spring 76, and both the second pickup rollers 71a and 71b are accommodated in the paper feed cassette 33. The surface of the uppermost sheet P is contacted at the same timing. At this time, the second pickup roller 71a rotates in the direction of the arrow R1 in FIG. 3 and the second pickup by the linked operation of the drive gear 64a, the idle gear 64b, and the driven gear 64c as the rotary shafts 72a and 72b rotate. The roller 71b contacts the uppermost sheet P almost simultaneously while rotating in the direction of the arrow R2 in FIG. 3, and the sheet P is bent and bent so as to be drawn toward the center of the sheet by the rotational force (see FIG. 6). Thereby, as shown in FIG. 6, the central portion of the paper P along the transport direction Y is curved in a mountain shape. At this time, the distance by which the second pickup rollers 71a and 71b pull the sheet toward the center of the sheet (that is, the distance by which the sheet is bent in the left-right direction) And

  The above is the rotation operation of the second pickup rollers 71a and 71b.

  Next, the linkage operation between the first pickup rollers 51a and 51b and the second pickup rollers 71a and 71b at the start of the sheet conveying process will be described.

  As shown in FIG. 3, the half-moon-shaped first pick-up rollers 51a and 51b are located above the half-moon roller portion at the beginning of the paper transporting process. There is no contact. Further, the solenoid 95 is switched from the off state to the on state, and the bevel gears 62a and 62b are brought into the meshing state (the state shown in FIG. 5).

  In this state, the rotation of the drive gear 98 by the driving force of the drive source 99 causes the rotation shaft 52 of the first pickup rollers 51a and 51b to start rotating via the intermediate gear 54 and the rotation shaft gear 53, and the first The rotation shafts 72a and 72a of the second pickup rollers 71a and 71b start to rotate through the tenth gears 61a to 61j and the drive belts 61m and 61n. Then, as described above, each of the second pickup rollers 71a and 71b descends and contacts the paper P against the elastic force of the torsion coil spring 76, and draws the paper P toward the center of the paper by the rotational force. And bent (see FIG. 6). As a result, an air layer is easily formed between the uppermost sheet P and the sheet P below the uppermost sheet P, and separation of the sheet is promoted.

  On the other hand, when the paper P is in the state shown in FIG. 6, the first pickup rollers 51a and 51b that have started rotating come into contact with the paper P bent in a curved shape. When the solenoid 95 is turned off at this point, the meshing of the bevel gears 62a and 62b is released, so that the drive transmission from the drive source 99 to the rotary shafts 72a and 72b is cut off and the paper P is in contact. The second pickup rollers 71 a and 71 b are lifted upward by the urging force of the torsion coil spring 76 and are separated from the paper P. Thus, thereafter, the sheet P is transported in the transport direction Y in a state of undulating waves in the left-right direction as shown in FIG. 7 by the rotational force of only the first pickup rollers 51a and 51b. In addition, the conveyance in the state where the wave is struck is gradually canceled by the elastic restoring force of the subsequent sheet P itself, and finally, the sheet is transported by the first pickup rollers 51a and 51b in a flat state as in the prior art. Will be.

  The above operation is controlled by a transport process control unit that controls the entire paper transport process, although not shown.

  The timing for turning off the solenoid 95 is determined as follows. In other words, is it attached to the device body? The distance between the position of the uppermost sheet stored in the sheet feeding cassette 33 and the positions of the second pickup rollers 71a and 71b lifted upward by the torsion coil spring 76 is always a substantially constant distance. Become. Therefore, the timing at which the second pickup rollers 71a and 71b come into contact with the paper P can be obtained by calculating, for example, the rotational speed (rotational pitch) of the drive gear 64a. Therefore, in this embodiment, the timing for turning off the solenoid 95 is obtained in advance by the above calculation. However, instead of such a calculation, the solenoid 95 may be turned off by detecting that the second pickup rollers 71a and 71b actually contact the paper P. Specifically, since the load is applied to the drive source 99 when the second pickup rollers 71a and 71b contact the paper P, the solenoid 95 is turned off by detecting this load (for example, the drive current value of the motor). You may detect the timing to do. In addition, the curved portion of the paper may be directly detected from above by using, for example, a reflective optical sensor.

  FIG. 8 shows an embodiment in which the position and interval in the left-right direction of the second pickup rollers 71a and 71b can be arbitrarily changed in the rotation mechanism structure of the first pickup rollers 51a and 51b and the second pickup rollers 71a and 71b configured as described above. It is an example.

  There is a possibility that sheets of various sizes such as B5, A4, B4, and A3 are stored in the sheet feeding cassette 33, for example. Therefore, the side guides 61 and 61 shown in FIG. 2 are configured to be capable of reciprocating (reciprocating slide) in the left-right direction. In this case, for example, when the arrangement positions and intervals of the second pickup rollers 71a and 71b are fixedly arranged according to the A4 size, for example, when A3 size paper is stored in the paper feed cassette 33, both Since the distance between the pickup rollers 71a and 71b is too small in the A3 size, there is a possibility that a curve suitable for the paper width cannot be formed. In order to solve such a problem, in this embodiment, as shown in FIG. 8, the rotation shafts 72a and 72b of the second pickup rollers 71a and 71b can be moved in the left-right direction using a rack and pinion. . FIG. 8 is a schematic plan view showing the structure of the rack and pinion.

  That is, one pinion 81 is arranged and fixed on a ceiling surface in the apparatus main body (not shown), and a pair of racks 82 and 83 are arranged on the ceiling surface so as to be movable left and right so as to face the front and rear of the pinion 81. And the cylindrical shaft holding parts 84 and 84 are formed in one edge part of these racks 82 and 83, respectively, and each rotating shaft 72a, 72b of 2nd pick-up roller 71a, 71b is formed in this shaft holding part 84,84. Are configured to be rotatably inserted and held. Further, a shaft holding portion 84 provided at an end portion of at least one rack 82 and one side guide 91 opposed to the shaft holding portion 84 are connected by a spring 86. However, the shaft holding portion 84 provided at the end portion of the other rack 83 and the other side guide 91 opposed to the shaft holding portion 84 may also be connected by the spring 86. Accordingly, when the side guide 91 is slid in the left-right direction in accordance with the size of the stored paper, both racks 82 and 83 are moved in conjunction with this, and the rotation shafts 72a and 72b of the second pickup rollers 71a and 71b are moved. Since the interval changes, the second pickup rollers 71a and 71b always move to a position suitable for the stored paper size.

  In addition, in order to enable the rotation shafts 72a and 72b to move in the left-right direction in this way, the first to tenth gears 61a to 61j and the drive belts 61m and 61n shown in FIG. 5 are also configured to be movable in the left-right direction. There is a need. That is, it cannot be directly attached to an inner wall surface (not shown) of the apparatus main body in which the paper feed cassette 33 is accommodated. Therefore, in this embodiment, as shown in FIG. 9, the first gear 61a to the sixth gear 61f (including the solenoid 95 and the drive source 99) are fixed to one slide substrate 88, and the remaining seventh gear. The tenth gear 61j from 61g may be fixed to another slide substrate 89, and these slide substrates 88 and 89 may be attached to an inner wall surface (not shown) of the apparatus main body so as to be slidable in the left-right direction. Or you may attach to the racks 82 and 83 corresponding not to an inner wall surface. That is, the slide substrate 88 and the rack 82 may be attached integrally, and the slide substrate 89 and the rack 83 may be attached integrally.

  Further, by using such a rack and pinion, the interval between the two rotating shafts 72a and 72b changes, and this change can be configured to be absorbed in the portion of the first drive belt 61m. Is possible. That is, as shown in FIG. 10, a tension pulley 87 that is slidable in the vertical direction is arranged in the substantially central portion of the first drive belt 61m, and this tension pulley 87 is adapted to the approach and separation of the two rotary shafts 72a and 72b. It may be configured to move up and down. Thus, by deforming the first drive belt 61m with the tension pulley 87, it is possible to cope with a change in the interval between the two rotary shafts 72a and 72b without impairing the drive transmission force.

1 is an explanatory diagram illustrating an outline of an internal configuration of a multifunction peripheral as an image forming apparatus according to the present invention. FIG. It is the schematic plan view which looked at the paper feed cassette in which the 1st pickup roller and the 2nd pickup roller are arranged from the upper part. It is the schematic perspective view which looked at the paper feed cassette in which the 1st pick-up roller and the 2nd pick-up roller are arranged from the upper slanting direction. It is a front view which expands and shows the part of a 1st pick-up roller and a 2nd pick-up roller. It is explanatory drawing which shows the structure of the rotation mechanism of a 1st pick-up roller and a 2nd pick-up roller, (a) is a schematic plan view, (b) is a schematic front view, (c) is a schematic side view. FIG. 9 is a partially enlarged perspective view of a sheet feeding cassette portion showing a state where a sheet is bent by a second pickup roller. FIG. 6 is a partially enlarged perspective view of a sheet feeding cassette portion showing a state in which a bent sheet is conveyed (pickup) by a first pickup roller. FIG. 6 is a plan view of an essential part showing an example of a mechanism structure for allowing the position and interval of the second pickup roller in the left-right direction to be arbitrarily changed in the rotation mechanism structure of the first pickup roller and the second pickup roller shown in FIG. 5. is there. FIG. 6 is a schematic plan view showing an example of a mechanism structure for enabling the position and interval of the second pickup roller in the left-right direction to be arbitrarily changed in the rotation mechanism structure of the first pickup roller and the second pickup roller shown in FIG. 5. . (A), (b) is explanatory drawing which shows the example which absorbs the change of the space | interval of two rotating shafts in the part of a 1st drive belt. It is explanatory drawing which looked at the paper feed cassette of the conventional paper feeder from the top. (A) is the sectional view on the A2-A2 line of FIG. 11, (b) is the sectional view on the B2-B2 line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunction machine 2 Scanner part 3 Image formation part 4 Automatic document feeder 31 Image formation system 32 Paper conveyance system 31b Photosensitive drum 33 Paper feed cassette 34 Manual feed tray 36 Main conveyance path 36b Pickup roller 36d Registration roller 37 Reverse conveyance path 51 (51a, 51b) First pickup roller 52 Rotating shaft 53 Rotating shaft gear 54 Intermediate gears 61a to 61j First to tenth gears 61m First driving belt 61n Second driving belts 62a and 62b Bevel gears 64a Driving gear 64b Idle Gear 64c Driven gear 71 (71a, 71b) Second pickup rollers 72a, 72b Rotating shaft 73a, 73b Support shaft 74 Arm rod 74a Insertion hole 74b Insertion hole 87 Tension pulley 88,89 Slide substrate 95 Solenoid 98 Drive gear 99 Drive source 99a Shaft P paper

Claims (8)

In a paper feeding device provided with transporting means for transporting paper stored in a paper feeding cassette one by one from the top in the paper transporting direction by a first pickup roller arranged in the left-right direction orthogonal to the paper transporting direction,
A sheet feeding device comprising: a second pickup roller that is arranged in a pair in the left-right direction and that bends and curls a sheet stored in a sheet feeding cassette in the left-right direction.   2. The sheet feeding device according to claim 1, wherein the first pickup roller is configured to bend the sheet in the left-right direction by the second pickup roller and then to contact the sheet and convey the sheet in the sheet conveying direction.   3. The sheet feeding device according to claim 1, wherein a rotation direction of the pair of second pickup rollers is a reverse rotation direction. 4.   4. The sheet feeding device according to claim 3, wherein the rotation direction of the second pickup roller is a direction in which a sheet is curved between a pair of second pickup rollers. 5. At the left and right corners of the transport downstream end of the paper feed cassette, a paper front end pressing plate for holding the left and right corners of the front end side of the stored paper is disposed,
The distance by which the sheet is bent in the left-right direction by the second pickup roller is a distance at which the left and right end corners of the sheet do not come off from the sheet end pressing plate. The paper feeder described.   6. The sheet feeding device according to claim 1, wherein the first and second pickup rollers are rotated by driving from the same driving source.   The sheet feeding device according to any one of claims 1 to 6, wherein the second pickup roller is provided so as to be reciprocally movable in a left-right direction orthogonal to a sheet conveyance direction.   An image forming apparatus comprising the paper feeding device according to claim 1.

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