JP4854559B2 - Paper feeder - Google Patents

Description

  The present invention relates to a sheet feeding device for sequentially pulling out and transporting a large number of recording sheets stacked and accommodated in a sheet feeding cassette.

  This type of paper feeding device is provided in a paper feeding cassette such as a copying machine, a printer, or a facsimile machine. The recording paper is pulled out from the paper feeding cassette, and the recording paper is conveyed and supplied to a print processing unit for characters and images. To do.

  In general, a large number of recording sheets (generally 200 to 2,000 sheets) are stacked and accommodated in a sheet feeding cassette. The paper feeding device includes a pickup roller that is pressed against the surface of the uppermost recording paper in the paper feeding cassette, a paper feeding roller and a surface member facing the paper feeding roller, and the recording in the paper feeding cassette is performed by the pickup roller. The paper is pulled out, the recording paper is fed one by one between the paper feed roller and the baffle member, and the recording paper is conveyed and supplied by the paper feed roller.

  5A and 5B are a cross-sectional view and a plan view showing a conventional paper feeder. The sheet feeding device includes a pickup roller 201, a sheet feeding roller 202, and a sucker plate 203 that is in contact with the lower peripheral surface of the sheet feeding roller 202, and these rollers 201, 202 are located near the upper right end of the sheet feeding cassette 204. Is arranged. These rollers 201 and 202 are pivotally supported by respective shafts 201a and 202a. The pulleys 201b and 202b are fixed to one end of these shafts 201a and 202a, and an endless shape is provided between the pulleys 201b and 202b. The drive belt 205 is bridged. The shaft 202b on the paper feed roller 202 side is rotationally driven in the direction of the arrow, and this rotation is transmitted to the shaft 201a of the pickup roller 201 by the pulleys 201b and 202b and the drive belt 205, and this shaft 201a is also rotated in the direction of the arrow. The pickup roller 201 and the paper feed roller 202 are rotated in the same arrow direction.

  Further, the shaft 201a of the pickup roller 201 is supported so as to be rotatable around the shaft 202a of the paper feed roller 202, and the shaft 201a of the pickup roller 201 is urged upward by a spring or the like (not shown). When the shaft 202b on the paper feed roller 202 side is driven to rotate in the direction of the arrow, a rotational moment is generated around the shaft 202a, and the shaft 201a of the pickup roller 201 rotates and moves downward against the biasing force of the spring. The pickup roller 201 is lowered and pressed against the recording paper in the paper feed cassette 204.

  On the other hand, the paper feed cassette 204 is provided with a recording paper trailing edge pressing plate 206 with which the trailing edge of the recording paper abuts on the left side of the bottom surface, and the recording paper leading edge that presses both corners of the recording paper on both sides near the right edge of the bottom surface. An aligning member 207 is provided, and recording sheet both-side restricting plates 208 for aligning both ends of the recording sheet are provided on both sides of the bottom surface. In addition, a recording paper stacking plate 211 that overlaps the substantially right half of the bottom surface of the paper feed cassette 204 is provided, and the left end 211 a of the recording paper stacking plate 211 is pivotally supported at the approximate center of the bottom surface of the paper feed cassette 204. Further, a rotating plate 212 is disposed below the recording paper stacking plate 211, the right end 212a of the rotating plate 212 is pivotally supported at the right end corner of the bottom surface of the paper feed cassette 204, and the rotating plate 212 is supported by a spring or the like (not shown). The recording sheet stacking plate 211 is lifted by the rotating plate 212 by biasing it clockwise.

  In this paper feed cassette 204, a large number of recording papers are arranged in an inner space surrounded by the recording paper trailing edge pressing plate 206, each recording paper leading edge aligning member 207, and each recording paper both-side regulating plate 208, and each recording paper is It is placed on the recording paper stacking plate 211. At this time, the right end of the recording paper stacking plate 211 is lifted by the rotating plate 212 and the leading edge of each recording paper is lifted until both corners of the recording paper come into contact with the claws 207a of the respective recording paper leading edge aligning members 207.

  In this state, when the sheet feeding roller 202 is driven to rotate, the pickup roller 201 rotates and moves around the shaft 202 a of the sheet feeding roller 202 while rotating, and the pickup roller 201 moves down the uppermost layer in the sheet feeding cassette 204. Is pressed against the surface of the recording paper. Then, friction is generated between the rotating pickup roller 201 and the surface of the uppermost recording sheet, and this recording sheet is pulled out in the rotation direction of the pickup roller 201 and guided between the sheet feeding roller 202 and the suction plate 203. The paper feed roller 202 further conveys the recording paper while sandwiching the recording paper between the paper plate 203. Further, when a plurality of recording sheets are pulled out while being overlapped, each recording sheet is rolled and conveyed between the sheet feeding roller 202 and the suction plate 203 one by one.

  When such a recording sheet is pulled out and conveyed, the recording sheet must be conveyed in parallel with the conveying direction. If the recording paper is transported obliquely, jamming of the recording paper occurs or characters, images, etc. are printed obliquely on the recording paper, resulting in poor printing.

  For this reason, as shown in FIGS. 5A and 5B, in the paper feed cassette 204, both side edges of the recording paper are aligned by the recording paper both-side regulating plates 208 regardless of the recording paper size, and are indicated by a one-dot chain line. The center of the recording sheet shown is made to coincide with the center of the conveyance path, and the centers of the pickup roller 201 and the paper feed roller 202 are also made to coincide with the center of the recording sheet shown by the alternate long and short dash line, and the conveyance force of each roller 201, 202 is It acts on the center to prevent the skew of the recording paper.

  In recent years, because of the “voidless printing” relationship in the print processing unit, recording is performed with the center of the recording paper aligned with the center of the conveyance path, regardless of the recording paper size. More and more paper is being transported. Also in this respect, a configuration in which the conveying force of each of the rollers 201 and 202 is applied to the center of the recording paper is preferable.

  Previously, the recording paper was sometimes transported with the side edge of the recording paper as the reference and the side edge of the recording paper aligned with the fixed position of the transport path, but in this case, depending on the size of the recording paper, Since the central position of the recording paper has changed, the contact position of the pickup roller and paper feed roller with respect to the surface of the recording paper has also moved away from the center of the recording paper, and the conveying force of each roller has acted near the side edge of the recording paper. Sometimes skewed.

  By the way, in the paper feed cassette 204, when the recording paper is repeatedly pulled out at a high speed, frictional charging occurs between the recording paper that is pulled out and the recording paper that overlaps with the recording paper. May be accumulated on a plurality of recording sheets, and these recording sheets may be attracted to each other.

  In addition, the humidity of the recording paper is kept low when the paper is wrapped in units of about 1,000 sheets. However, after the paper is removed from the paper and set in the paper cassette, the recording paper absorbs moisture. The humidity becomes high, and this may cause a plurality of recording sheets to be adsorbed to each other.

  Thus, in a state where a plurality of recording papers are adsorbed to each other, the pickup roller 201 slides on the surface of the uppermost recording paper and idles, and the recording paper is fed forward. Alternatively, a plurality of recording sheets are pulled out while being overlapped, and the recording sheets are conveyed without being separated one by one between the paper feed roller 202 and the baffle plate 203, and the recording sheets are jammed or have poor printing. Occurred.

  For this reason, the conveyance speed by the pickup roller 201 is made faster than the conveyance speed by the paper feed roller 202, and the recording paper is slightly bent between the rollers 201 and 202, and a plurality of recording papers are pulled out while being overlapped. However, due to the bending of each recording sheet, air enters between the recording sheets so that each recording sheet is easily wound.

Further, in Patent Document 1, the recording roller is repeatedly pressed and separated from the recording paper to bend the recording paper so that each recording paper can be easily rolled.
Japanese Unexamined Patent Publication No. 2000-44096

  However, in recent years, the printing processing speed has been remarkably increased, and the recording paper conveyance speed has also increased, and the speed difference between the conveyance speed by the pickup roller 201 and the conveyance speed by the paper feed roller 202 can be increased. This is difficult, and it is impossible to expect the effect of curling each recording sheet due to the difference in the conveyance speed between the rollers 201 and 202.

  Moreover, even if the recording paper is bent by repeatedly pressing and separating the pickup roller with respect to the recording paper as in Patent Document 1, the recording sheets adsorbed to each other are similarly bent. In addition, almost no air enters between the recording sheets, and it is impossible to expect the effect of each recording sheet. In particular, a thin recording paper or a surface-coated recording paper has almost no effect.

  Furthermore, if the pickup roller is repeatedly pressed and separated, the position of the leading edge of the recording paper is displaced, which may cause the skew of the recording paper.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a paper feeding device that can effectively feed and transport recording sheets adsorbed to each other.

In order to solve the above problems, the present invention is disposed on the downstream side of the pickup roller in pressure contact with the surface of the recording paper in the paper feed cassette and pulling out and transporting the recording paper, and in the recording paper transport direction, In a paper feeding device comprising a paper feeding roller for transporting the recording paper conveyed by the pickup roller one by one and a baffle member facing the paper feeding roller, both side edges of the recording paper are aligned, A recording paper both-side restricting plate that positions a central position of the recording paper in a direction orthogonal to the recording paper conveyance direction at a fixed position, the pickup roller being disposed at the central position of the recording paper, and a plurality of sets of the paper feeds The roller and the separating member are separated from the central position of the recording paper by different distances in a direction orthogonal to the recording paper transport direction. It was placed in each of the positions, and the peripheral speed of the pick-up roller is set higher than the peripheral surface speed of each of the paper feed roller.

  The plurality of sets of paper feed rollers and the baffle members are the same.

  Further, the pickup roller and the plurality of paper feed rollers are driven to rotate in the same direction.

  The pickup roller, the plurality of sets of paper feed rollers, and the baffle members pull out the recording paper from the paper feed cassette one by one and convey the recording paper to the recording paper conveyance path.

  According to the present invention as described above, the plurality of sets of paper feed rollers and the baffle members are arranged apart from each other in the direction perpendicular to the recording paper conveyance direction. For this reason, the recording paper is rolled up at a plurality of locations by each set of paper feed rollers and the baffle member. Each overlapping recording paper is effectively struck, and each recording paper is separated and fed one by one. can do.

  Further, the pickup roller is disposed at the center position of the recording paper in the direction orthogonal to the recording paper transport direction. In this case, since the center of the recording sheet is pulled out by the pickup roller while the pickup roller is in contact with the center position of the recording sheet, the recording sheet is not skewed.

  In addition, each pair of paper feed rollers and the baffle members are disposed at respective positions separated from each other by different distances from the center of the recording paper in the direction orthogonal to the recording paper transport direction. Alternatively, the respective separation distances between the pickup roller and each pair of the paper feed roller and the buckling member are different from each other.

  In this case, the recording paper fulcrum position by the pick-up roller and the separation distance between the recording paper fulcrum positions by one set of paper feed rollers and the baffle member, the recording paper fulcrum position by the pickup roller and the other set of paper feeds Since there is a difference in the separation distance between the fulcrum positions of the recording paper by the roller and the baffle member, a difference occurs in the amount of deflection of the recording paper between them, and each recording paper can be reliably rolled.

  In addition, since the sizes and materials of the paper feed rollers and the baffle members of each set are the same, the feeding timing of the leading edge of the recording paper by each paper feeding roller is easily aligned, and skewing of the recording paper is difficult to occur.

  Further, the pickup roller and the plurality of paper feed rollers are driven to rotate in the same direction, and the recording paper is pulled out and conveyed. Alternatively, the pickup roller, each pair of paper feed rollers, and the baffle member pull out the recording paper from the paper feed cassette and feed it one by one, and transport this recording paper to the recording paper transport path.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an image forming apparatus to which an embodiment of a paper feeding device of the present invention is applied. The image forming apparatus 100 acquires image data read from a document, or acquires image data received from the outside, and forms a monochrome image indicated by the image data on a recording sheet. Are roughly divided into a document transport unit (ADF) 101, an image reading unit 102, a print processing unit 103, a recording paper transport unit 104, and a paper feed unit 105.

  When at least one document is set on the document set tray 11, the document transport unit 101 pulls out the document one by one from the document set tray 11 and transports the document to the document reading window 102 a of the image reading unit 102. The document is guided and passed, and the document is discharged to the discharge tray 12.

  A CIS (Contact Image Sensor) 13 is disposed above the document reading window 102a. When the document passes through the document reading window 102a, the CIS 13 repeatedly reads the image on the back side of the document in the main scanning direction and outputs image data indicating the image on the back side of the document.

  Further, the image reading unit 102 exposes the surface of the document by the lamp of the first scanning unit 15 when the document passes through the document reading window 102a, and the mirror of the first and second scanning units 15 and 16 from the document surface. The reflected light is guided to the imaging lens 17, and an image of the document surface is formed on a CCD (Charge Coupled Device) 18 by the imaging lens 17. The CCD 18 repeatedly reads an image on the document surface in the main scanning direction and outputs image data indicating the image on the document surface.

  Further, when the document is placed on the platen glass on the upper surface of the image reading unit 102, the first and second scanning units 15 and 16 are moved while maintaining a predetermined speed relationship with each other. The document surface on the platen glass is exposed, the reflected light from the document surface is guided to the imaging lens 17 by the first and second scanning units 15 and 16, and the image on the document surface is connected to the CCD 18 by the imaging lens 17. Image.

  The image data output from the CIS 13 or the CCD 18 is subjected to various image processing by a control circuit such as a microcomputer and then output to the print processing unit 103.

  The print processing unit 103 records a document indicated by image data on a recording sheet, and includes a photosensitive drum 21, a charger 22, an optical writing unit 23, a developing unit 24, a transfer unit 25, a cleaning unit 26, and A fixing device 27 and the like are provided.

  The photoconductor drum 21 is an organic photoconductor whose surface layer is made of an organic photoconductive material. The photoconductor drum 21 rotates in one direction, the surface is cleaned by the cleaning unit 26, and the surface is uniformly charged by the charger 22. Is done. The charger 22 may be of a charger type or of a roller type or a brush type that contacts the photosensitive drum 21.

  The optical writing unit 23 is a laser scanning unit (LSU) including two laser irradiation units 28a and 28b and two mirror groups 29a and 29b. In the optical writing unit 23, image data is input, laser light corresponding to the image data is emitted from the laser irradiation units 28a and 28b, and the laser light is transmitted through the mirror groups 29a and 29b. The drum 21 is irradiated to expose the uniformly charged surface of the photosensitive drum 21 to form an electrostatic latent image on the surface of the photosensitive drum 21.

  The optical writing unit 23 employs a two-beam method including two laser irradiation units 28a and 28b in order to cope with high-speed printing processing, thereby reducing the burden associated with increasing the irradiation timing.

  As the optical writing unit 23, an EL writing head or an LED writing head in which light emitting elements are arranged in an array can be used instead of the laser scanning unit.

  The developing device 24 supplies toner to the surface of the photosensitive drum 21 to develop the electrostatic latent image, and forms a toner image (also referred to as a visible image) on the surface of the photosensitive drum 21. The transfer unit 25 transfers the toner image on the surface of the photosensitive drum 21 onto the recording paper conveyed by the recording paper conveyance unit 104. The fixing device 27 heats and pressurizes the recording paper to fix the toner image on the recording paper. Thereafter, the recording sheet is further conveyed to the sheet discharge tray 47 by the recording sheet conveying unit 104 and discharged. The cleaning unit 26 removes and collects the toner remaining on the surface of the photosensitive drum 21 after development and transfer.

Here, the transfer unit 25 includes a transfer belt 31, a driving roller 32, a driven roller 33, an elastic conductive roller 34, and the like, and the transfer belt 31 is stretched around the rollers 32-34 and other rollers. Rotating. The transfer belt 31 has a predetermined resistance value (for example, 1 × 10 ⁹ to 1 × 10 ¹³ Ω / cm), and conveys the recording paper placed on the surface thereof. The elastic conductive roller 34 is pressed against the surface of the photosensitive drum 21 via the transfer belt 31, and presses the recording paper on the transfer belt 31 against the surface of the photosensitive drum 21. A transfer electric field having a polarity opposite to the charge of the toner image on the surface of the photosensitive drum 21 is applied to the elastic conductive roller 34, and the toner image on the surface of the photosensitive drum 21 is transferred to the transfer belt by the transfer electric field having the opposite polarity. 31 is transferred to a recording sheet on the recording medium 31. For example, when the toner image has a charge of (−) polarity, the polarity of the transfer electric field applied to the elastic conductive roller 34 is set to (+) polarity.

  The cleaning unit 26 presses the cleaning blade 26 </ b> A against the surface of the photosensitive drum 21 to remove residual toner and paper dust on the surface of the photosensitive drum 21.

  The fixing device 27 includes a heating roller 35 and a pressure roller 36. When the recording paper is conveyed to a pressure contact area (referred to as a nip area) between the heating roller 35 and the pressure roller 36, the recording paper is conveyed by the rollers 35 and 36, and unfixed toner on the recording paper. The image is heated and melted and pressed to fix the toner image on the recording paper.

  The recording paper transport unit 104 includes a plurality of pairs of transport rollers 41, a pair of registration rollers 42, a recording paper transport path 43, reverse transport paths 44a and 44b, a plurality of branching claws 45, and a pair of discharge rollers. A paper roller 46 and the like are provided.

  In the recording paper conveyance path 43, the recording paper is received from the paper feeding unit 105 and conveyed until the leading edge of the recording paper reaches the registration roller 42. At this time, since the registration roller 42 is temporarily stopped, the leading edge of the recording paper reaches and contacts the registration roller 42, and the recording paper is bent. The leading edge of the recording sheet is aligned parallel to the registration roller 42 by the elastic force of the bent recording sheet. Thereafter, the rotation of the registration roller 42 is started, the recording paper is conveyed to the transfer unit 25 of the print processing unit 103 by the registration roller 42, and the recording paper is further conveyed to the paper discharge tray 47 by the paper discharge roller 46. .

  The registration roller 42 is stopped and rotated by switching on and off the clutch between the registration roller 42 and the drive shaft, or by switching on and off the motor that is the drive source of the registration roller 42.

  When an image is also recorded on the back side of the recording paper, each branch claw 45 is selectively switched and the recording paper is guided from the recording paper conveyance path 43 to the reverse conveyance path 44b to temporarily convey the recording paper. Further, each of the branching claws 45 is selectively switched again, the recording sheet is introduced from the reverse conveying path 44b to the reverse conveying path 44a, the recording sheet is reversed, and then the recording sheet is reversed. Through the registration roller 42 of the recording paper conveyance path 43.

  Such conveyance of the recording paper is referred to as switchback conveyance. By this switchback conveyance, the front and back sides of the recording paper are reversed, and at the same time, the leading edge and the trailing edge of the recording paper are also switched. Accordingly, when the recording paper is reversed and returned, the trailing edge of the recording paper comes into contact with the registration roller 42 and the trailing edge of the recording paper is aligned in parallel with the registration roller 42. Is transferred to the transfer unit 25 of the print processing unit 103 to print on the back surface of the recording paper, and the unfixed toner image on the back surface of the recording paper is heated and melted by the nip area between the rollers 35 and 36 of the fixing device 27. The toner image is fixed on the back surface of the recording paper by being pressurized, and then the recording paper is conveyed to the paper discharge tray 47 by the paper discharge roller 46.

  In the recording paper conveyance path 43 and the reverse conveyance paths 44a and 44b, sensors for detecting the position of the recording paper are arranged in various places, and the conveyance roller and the registration roller are driven based on the position of the recording paper detected by each sensor. Control is performed to transport and position the recording paper.

  The paper feed unit 105 includes a plurality of paper feed cassettes 51. Each paper feed cassette 51 is a tray for storing recording sheets of various sizes, and is provided below the image forming apparatus 100. Each paper feed cassette 51 includes a pickup roller for pulling out the recording paper one by one, and sends out the drawn recording paper to the recording paper conveyance path 43 of the recording paper conveyance unit 104.

  Since the image forming apparatus 100 is intended for high-speed printing processing, each paper feed cassette 51 has a capacity capable of storing 500 to 1500 standard size recording sheets.

  The paper discharge tray 47 is disposed on the left side surface in the drawing. Instead of the paper discharge tray 47, a post-processing device (stapling, punching, etc.) of paper discharge recording paper and a plurality of stages of paper discharge trays can be arranged as options.

  In such an image forming apparatus 100, the printing process speed is increased to improve usability. For example, when A4 size recording paper is used, the recording paper conveyance speed is set to 100 sheets / minute (process speed 450 to 600 mm / sec).

  Next, the paper feeding device of this embodiment will be described. The sheet feeding device is provided for each sheet feeding cassette 51 of the sheet feeding unit 105, and the recording sheets are pulled out one by one from the sheet feeding cassette 51, and the pulled recording sheets are fed to the recording sheet conveying path 43 of the recording sheet conveying unit 104. To send to.

  2A and 2B are a cross-sectional view and a plan view showing a paper feed cassette 51 to which the paper feed device of this embodiment is applied. The sheet feeding device includes a pickup roller 61, two pairs of sheet feeding rollers 62a and 62b, and a sheet plate 63a and 63b. The pickup roller 61 is disposed above the right inner side of the sheet feeding cassette 51, and each group The sheet feeding rollers 62a and 62b and the sucker plates 63a and 63b are arranged above the right outer side of the sheet feeding roller 51.

  The pickup roller 61 is supported by a shaft 61a, and a pulley 61b is fixed to one end of the shaft 61a. Each of the paper feed rollers 62a and 62b is supported by a common shaft 62c, and a pulley 62d is fixed to one end of the shaft 62c. An endless drive belt 64 is bridged between the pulleys 61b and 62d.

  The diameters, materials, and the like of the paper feed rollers 62a and 62b are the same. Moreover, the size, material, etc. of each of the bottom plates 63a, 63b are the same. That is, the one paper feed roller 62a and the bottom plate 63a and the other paper feed roller 62b and the bottom plate 63b are the same.

  The frame 65 rotatably supports both ends of the shafts 61a and 62c, and always maintains a constant distance between the shafts 61a and 62c.

  The frame 65 is pivotally supported by the shaft 62c of each paper feed path roller 62a, 62b. The frame 65 is rotatably supported around the shaft 62c of the paper feed path rollers 62a and 62b. The pickup roller 61 and the shaft 61a also rotate around the shaft 62c of the paper feed path rollers 62a and 62b. Supports movable. The frame 65 is urged upward by a spring or the like (not shown). Due to the urging force of the spring or the like, the frame 65, the pickup roller 61, and the shaft 61a normally rotate and move upward to a fixed position around the shaft 62c of each paper feed path roller 62a, 62b.

  Here, one shaft 62c is connected to the rotation output shaft of the drive mechanism on the image forming apparatus 100 main body side, and this shaft 62c is rotationally driven in the arrow direction J. As a result, the paper feed rollers 62a and 62b are rotationally driven, and the rotation of the shaft 62c is transmitted from the pulley 62d → the drive belt 64 → the pulley 61b, so that the shaft 61a and the pickup roller 61 are driven to rotate in the same arrow direction J. .

  Further, when the shaft 62c of each paper feed roller 62a, 62b is rotationally driven in the arrow direction J by the drive mechanism on the main body side of the image forming apparatus 100, the rotation in the arrow direction K about the shaft 62c of each paper feed roller 62a, 62b. A moment is generated, and the frame 65, the pickup roller 61, and the shaft 61a rotate downward against an urging force of a spring or the like, and the pickup roller 61 descends to record on the uppermost layer in the paper feed cassette 51. Pressed against the paper surface. In this state, the uppermost recording paper is pulled out by the pickup roller 61, and the recording paper is sent out between the paper feed rollers 62a and 62b and the suction plates 63a and 63b, and is recorded by the paper feed rollers 62a and 62b. The paper is conveyed.

  Further, the ratio of the respective diameters of the pickup roller 61 and the respective feed rollers 62a and 62b or the respective diameters of the respective pulleys 61b and 62d is appropriately set, and the peripheral surface speed of the pickup roller 61 is set to the respective feed rollers 62a, The circumferential speed of 62b is slightly higher, and the recording paper conveyance speed by the pickup roller 61 is slightly higher than the recording paper conveyance speed by the paper feed rollers 62a and 62b. For this reason, the recording paper bends between the pickup roller 61 and the paper feed rollers 62a and 62b.

  Further, in FIG. 2B, the center position of the recording paper in the paper feed cassette 51 in the direction orthogonal to the recording paper transport direction is indicated by a one-dot chain line, but the center of the pickup roller 61 overlaps with the one-dot chain line. The pickup roller 61 is positioned on the front side. That is, the pickup roller 61 is arranged on a one-dot chain line passing through the center position of the recording paper.

  Further, as shown in FIG. 3, the paper feed rollers 62a and 62b are arranged on both sides of a one-dot chain line passing through the central position of the recording paper, and the distance X1 between one paper feed roller 62a and the one-dot chain line and the other paper feed roller are arranged. The distance Y1 between the paper roller 62b and the alternate long and short dash line is made different from each other. Here, the distance X1 is longer than the distance Y1, and one of the paper feed rollers 62a is located farther from the one-dot chain line than the other paper feed roller 62b.

  On the other hand, the sheet feeding cassette 51 is provided with a recording sheet trailing edge pressing plate 71 with which the trailing edge of the recording sheet abuts on the left side of the bottom surface, and the leading edge of each recording sheet that presses both corners of the recording sheet on both sides near the right edge of the bottom surface. An aligning member 72 is provided, and recording sheet both-side restricting plates 73 for aligning both ends of the recording sheet are provided on both sides of the bottom surface. In addition, a recording paper stacking plate 74 that overlaps the substantially right half of the bottom surface of the paper feed cassette 51 is provided, and the left end 74 a of the recording paper stacking plate 74 is pivotally supported at the approximate center of the bottom surface of the paper feed cassette 51. Further, a rotating plate 75 is disposed below the recording paper stacking plate 74, the right end 75a of the rotating plate 75 is pivotally supported at the right end corner of the bottom surface of the paper feed cassette 51, and the rotating plate 75 is supported by a spring or the like (not shown). The recording paper stacking plate 74 is urged clockwise and the right end of the recording paper stacking plate 74 is lifted by the rotating plate 75.

  In this paper feed cassette 51, a large number of recording papers are arranged in an inner space surrounded by the recording paper trailing edge pressing plate 71, each recording paper leading edge aligning member 72, and each recording paper both-side regulating plate 73, It is placed on the recording paper stacking plate 74. At this time, since the right end of the recording paper stacking plate 74 is lifted by the rotating plate 75, the leading end of each recording paper is lifted until both corners of the leading end of each recording paper come into contact with the claws 72a of the respective recording paper leading edge aligning members 72. It is done.

  In this state, when each of the paper feed rollers 62a and 62b is driven to rotate, the pickup roller 61 rotates while rotating around the shaft 62c of each of the paper feed rollers 62a and 62b, and the pickup roller 61 feeds the paper. It is pressed against the uppermost recording paper surface in the cassette 51. Then, friction is generated between the rotating pickup roller 61 and the uppermost recording paper surface, and this recording paper is pulled out in the rotation direction of the pickup roller 61. The recording paper is guided between the paper feed rollers 62a and 62b and the suction plate 63 and is conveyed by the paper feed rollers 62a and 62b.

  Incidentally, in order to allow various sizes of recording paper to be placed and accommodated, the recording paper trailing edge pressing plate 71 can be moved back and forth, and each recording paper both-side regulating plate 73 can be moved left and right. Further, in order to prevent the center position of the recording paper from deviating from the alternate long and short dash line, each recording paper both-side regulating plate 73 is configured to move symmetrically.

  By the way, when the recording paper is repeatedly pulled out from the paper feeding cassette 51, frictional charging occurs between the uppermost recording paper to be pulled out and the recording paper overlapping thereunder, and the charge due to this frictional charging causes the recording on the upper side to be recorded. In some cases, the recording sheets are sequentially accumulated from the sheet to the lower recording sheet, and the recording sheets are attracted to each other. In addition, after each recording sheet is taken out from the packaging sheet and loaded and accommodated in the sheet feeding cassette 51, each recording sheet absorbs moisture, which may cause the recording sheets to be attracted to each other.

  When the recording sheets are attracted to each other, as the uppermost recording sheet is pulled out by the pickup roller 61, the lower recording sheet is pulled out while being overlapped with the uppermost recording sheet. In some cases, the recording sheets are pulled out while being overlapped, and a plurality of recording sheets are pulled out at a time while being overlapped.

  If a plurality of recording sheets are sent to the print processing unit 103 while being overlapped, a jamming of the recording sheet occurs in the middle of the recording sheet, or the leading end of each recording sheet hits the photosensitive drum 21 and the photosensitive member The surface of the drum 21 is damaged. Alternatively, the heat of the heating roller of the fixing device 27 may be taken away by each recording sheet at a time, and the temperature of the heating roller may be lowered, resulting in a fixing failure.

  Therefore, in this embodiment, the two sets of paper feed rollers 62a and 62b and the suction plates 63a and 63b are arranged on both sides of the central position of the recording paper.

  When the overlapping recording sheets are guided between the two sets of paper feed rollers 62a and 62b and the suction plates 63a and 63b, the overlapping recording sheets are spread out at these two sets of locations. That is, the feeding roller is in direct contact with the uppermost recording paper at two locations spaced apart from each other, and the lower recording paper is prevented from being fed by friction with the lower plate so that the uppermost recording paper A difference in feeding amount occurs between the recording paper and the lower recording paper, and the uppermost recording paper is separated from the lower recording paper and sent out.

  In this way, since each recording sheet is fed and sent out at two places, as compared with the case where the recording sheet is fed out at one place by a pair of feeding rollers 201 and 202 as shown in FIG. The recording paper can be made more reliably.

  Further, as described above, since the recording paper transport speed by the pickup roller 61 is slightly higher than the recording paper transport speed by the paper feed rollers 62a and 62b, the recording paper on the paper feed rollers 62a and 62b side. Is slightly delayed. For this reason, the overlapped recording sheets bend between the pickup roller 61 and the sheet feeding rollers 62a and 62b.

  Since each recording sheet bends in this way, air enters between the recording sheets, and each recording sheet is more easily squeezed. Moreover, since the recording paper bends in front of the two pairs of paper feed rollers and the suction plate, the recording paper is compared with the case where the recording paper bends in front of the one pair of paper feed rollers and the suction roller as shown in FIG. Can bend more reliably, and the stacked recording sheets can be rolled more reliably.

  Further, as described above, one paper feed roller 62a is located farther from the one-dot chain line in the center of the recording paper than the other paper feed roller 62b. Therefore, as shown in FIG. 3, the distance X2 from the pickup roller 61 to the one paper supply roller 62a is longer than the distance Y2 from the pickup roller 61 to the other paper supply roller 62b. In this case, as shown in FIGS. 4A and 4B, the amount of deflection of the recording paper P between the pickup roller 61 and one paper feed roller 62a is between the pickup roller 61 and the other paper feed roller 62b. Therefore, the amount of deflection of the recording paper P is biased. When the deflection amount of the uppermost recording sheet P is biased, a gap is easily formed between the uppermost recording sheet P and the lower recording sheet P, and air is generated between the recording sheets P. As a result, the recording paper P is more easily squeezed.

  On the other hand, when the recording paper bends in front of the pair of paper feed rollers and the baffle plate as shown in FIG. 5, the recording paper P can be positioned at any position in the width direction as shown in FIG. Since the overlapping recording sheets P bend with substantially the same amount of bending, it is difficult to form a gap between the uppermost recording sheet and the lower recording sheet.

  Further, the pickup roller 61 is arranged on a one-dot chain line passing through the central position of the recording paper, and the respective paper feeding rollers 62a and 62b and the respective sucker plates 63a and 63b are arranged side by side in a direction orthogonal to the recording paper conveying direction. Then, the center of the recording paper is pulled out by the pickup roller 61, and the leading edge of the recording paper reaches each of the paper supply rollers 62a and 62b at the same timing. For this reason, the recording paper is not skewed.

  Further, the one paper feed roller 62a and the bottom plate 63a and the other paper feed roller 62b and the bottom plate 63b are the same as each other. For this reason, the feeding timing of the recording paper tip from one paper feed roller 62a and the suction plate 63a coincides with the feeding timing of the recording paper tip from the other paper feeding roller 62b and the suction plate 63b, and the recording paper is slanted. Will not be sent out.

  As described above, in this embodiment, the two pairs of paper feed rollers 62a and 62b and the baffle plates 63a and 63b are arranged on both sides of the one-dot chain line passing through the central position of the recording paper, and between the one paper feed roller 62a and the one-dot chain line. Since the distance X1 and the distance Y1 between the other paper feed roller 62b and the alternate long and short dash line are different from each other, it is possible to reliably roll over the recording sheets, and separate the recording sheets one by one. Can be transported. For this reason, it is possible to prevent the jamming of the recording paper, the fixing failure, the scratch on the photosensitive drum, and the like caused by the multiple feeding (simultaneous conveyance) of a plurality of recording papers.

  The present invention is not limited to the above-described embodiment, and can be variously modified without departing from the scope of the claims. For example, two sets of paper feed rollers and a separating member may be arranged at equal distances on both sides from a one-dot chain line passing through the central position of the recording paper. Even in this case, compared with the conventional example using only one set of paper feed rollers and a separating member as shown in FIG. In addition, three or more sets of paper feed rollers and a separating member may be arranged side by side in a direction orthogonal to the recording paper conveyance direction. In addition, the size and material of each pair of paper feed rollers and sawbing members, or the peripheral surface speed of each pair of paper feed rollers may be varied to set a difference in the separating ability of each pair.

1 is a cross-sectional view illustrating an image forming apparatus to which an embodiment of a paper feeding device of the present invention is applied. (A) And (b) is sectional drawing and the top view which show the paper feeding cassette to which the paper feeding apparatus of this embodiment is applied. FIG. 3 is a plan view showing an arrangement relationship between a pickup roller and each paper feed roller in the paper feed device of FIG. 2. (A), (b) is sectional drawing which shows the state of the recording paper curled by the paper feeder of FIG. 2, (c) shows the state of the recording paper curled by the conventional device of FIG. It is sectional drawing. (A) And (b) is sectional drawing and a top view which show the paper feeding cassette to which the conventional paper feeding apparatus is applied.

Explanation of symbols

51 Paper Feeding Cassette 61 Pickup Rollers 62a and 62b Paper Feeding Rollers 63a and 63b Scaffle Plate 64 Drive Belt 65 Frame 100 Image Forming Apparatus 101 Document Conveying Unit (ADF)
102 Image Reading Unit 103 Print Processing Unit 104 Recording Paper Conveying Unit 105 Paper Feeding Unit

Claims (4)

A pickup roller that is pressed against the surface of the recording paper in the paper feed cassette and pulls out and conveys the recording paper, and a recording paper that is disposed downstream of the pickup roller in the recording paper conveyance direction and is conveyed by the pickup roller is 1 In a paper feeding device comprising a paper feeding roller that conveys the paper one by one and a surface member facing the paper feeding roller,
Aligning both side edges of the recording paper, each recording paper both-side restricting plate for positioning the central position of the recording paper in a direction orthogonal to the recording paper transport direction,
The pickup roller is disposed at the center position of the recording paper,
A plurality of sets of the paper feed roller and the baffle member are arranged at respective positions separated from each other by different distances from a central position of the recording paper in a direction orthogonal to the recording paper transport direction,
2. A sheet feeding device, wherein a peripheral surface speed of the pickup roller is set higher than a peripheral surface speed of each of the sheet feeding rollers . The sheet feeding device according to claim 1 , wherein the plurality of sets of sheet feeding rollers and the buckling member are the same as each other. Feeder to claim 1 or 2 wherein the plurality of paper feed rollers and the pick-up roller, characterized in that it is driven to rotate in the same direction to each other. The pickup roller, the plurality of sets of paper feed rollers, and the baffle member pull out the recording paper from the paper feeding cassette and feed the recording paper one by one, and convey the recording paper to the recording paper conveyance path. The sheet feeding device according to any one of 1 to 3 .

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