JP4534878B2 - Sheet supply apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet supply apparatus that sequentially feeds sheets stacked in a sheet supply tray by a sheet supply roller and a separation member that is pressed against the sheet supply roller, and an image forming apparatus including the sheet supply apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a sheet supply device for sequentially feeding sheets such as sheets stacked in a sheet feeding tray is provided. This sheet supply apparatus is provided with a paper feed roller that feeds stacked sheets from the top by rotation. A separation member is pressed against the lower portion of the sheet feed roller, and when the sheet is sent out, the sheet is rolled at the pressure contact portion between the sheet feed roller and the separation member.

  In this sheet supply apparatus, when the sheets stacked in the sheet feeding tray are sent out, the second and subsequent sheets are easily conveyed along with the uppermost sheet, and the sheets are likely to be double-fed. For this reason, there has been proposed a sheet supply apparatus provided with a double feed prevention claw that protrudes into the sheet conveyance path and restricts the progress of the sheet (see, for example, Patent Document 1).

  However, with this double feed prevention claw, there is a limit to returning the sheet that has entered downstream from the pressure contact portion between the paper feed roller and the separating member, depending on the amount of sheet entry, and double feed of the sheet occurs. .

As another sheet supply device, a configuration has been proposed in which a separation roller that is pressed against a paper feed roller is movably provided in a holder by a spring (see, for example, Patent Document 2). In this configuration, when the uppermost sheet is fed out, the separation roller is moved by the paper feed roller to change the position, and when the separation roller is returned to the original position by the spring, the second sheet is returned. However, even in this configuration, when the sheet enters downstream from the pressure contact portion between the sheet feeding roller and the separation roller, the sheet cannot be returned depending on the amount of the entry, and double feeding occurs.
JP-A-8-217281 Japanese Patent Laid-Open No. 11-349167

  The present invention has been made in view of the above problems. When the stacked sheets are sequentially fed, the second and subsequent sheets enter the downstream side of the pressure contact portion between the sheet feeding roller and the separation member. An object of the present invention is to provide a sheet supply apparatus and an image forming apparatus that suppress the sheet feeding and prevent the double feeding of sheets.

In order to solve the above problem, a sheet feeding apparatus according to the invention described in claim 1 includes a sheet feeding roller that feeds a sheet, and a sheet stacking unit that can stack a plurality of sheets and presses the sheet against the sheet feeding roller. When the loosened separating member sheet in the paper feed roller and a press contact portion which is pressed against the arc-shaped portions in the sheet feeding direction upstream side Ru is abutted against the distal end of the sheets stacked on the sheet stacking means from said pressure contact portion A guide member rotatably supported in a circumferential direction of the arcuate portion, the arcuate portion returning the sheet to the sheet stacking unit when the sheet stacking unit descends Rotating and rotating in the direction of feeding a sheet when the sheet stacking means is raised .

According to the first aspect of the present invention, the sheets stacked on the sheet stacking unit are sent out by the rotation of the paper feed roller, and the fed-out sheet is rolled at the pressure contact portion between the paper feed roller and the separation member. At this time, a guide member is in contact with the leading end of the sheet stacked on the sheet stacking unit on the upstream side in the sheet feeding direction from the press contact portion, and the guide member is rotatably supported. As a result, before the sheet enters the pressure contact portion between the paper feed roller and the separation member, the guide member abutted on the leading edge of the sheet rotates to separate the sheet, so the pressure contact between the paper feed roller and the separation member. The second and subsequent sheets are suppressed from entering the downstream side of the section, and the double feeding of the sheets is prevented.
Further, since the sheet stacking unit descends when the arc-shaped portion of the guide member returns the sheet, the return of the sheet is not hindered. Further, when the arcuate portion of the guide member feeds the sheet, the sheet stacking means is raised, so that the sheet can be smoothly guided to the press contact portion.

According to a second aspect of the present invention, in the sheet feeding apparatus according to the first aspect, the arcuate portion of the guide member is provided with a protrusion so as to be orthogonal to the sheet feeding direction. Yes.

According to the second aspect of the present invention, since the sheet hits the projection of the arcuate portion of the guide member, the second and subsequent sheets are returned by the rotation of the guide member. For this reason, sheet separation performance can be improved without using a dedicated sheet returning means, which contributes to cost reduction.

According to a third aspect of the present invention, in the sheet feeding apparatus according to the first aspect, a sheet member having a larger frictional force with the sheet than the guide member is provided on the arc-shaped portion of the guide member. It is characterized by.

According to the third aspect of the present invention, the second and subsequent sheets are separated by the friction between the sheet and the sheet member by the sheet coming into contact with the sheet member of the arcuate portion of the guide member. For this reason, sheet separation performance can be improved without using a dedicated sheet returning means, which contributes to cost reduction.

  According to a fourth aspect of the present invention, in the sheet feeding apparatus according to any one of the first to third aspects, the guide member is rotated by a cam rotating. Yes.

  According to the fourth aspect of the present invention, the rotation of the guide member can be freely controlled by the rotation of the cam.

  According to a fifth aspect of the present invention, in the sheet supply apparatus according to the fourth aspect, the cam rotates in conjunction with the rotation of the paper feed roller.

  According to the fifth aspect of the present invention, by rotating the cam in conjunction with the rotation of the paper feed roller, a dedicated drive means for rotating the cam is not required, and the cost can be reduced.

  According to a sixth aspect of the present invention, in the sheet feeding apparatus according to any one of the first to fifth aspects, the guide member rotates in conjunction with the movement of the sheet stacking means. It is a feature.

  According to the sixth aspect of the present invention, the guide member rotates in conjunction with the movement of the sheet stacking means and comes into contact with the sheet, so that the sheet separation performance by the guide member can be further improved.

Invention according to claim 7, in the sheet feeding apparatus according to claim 1, wherein the arcuate portion of the guide member, when rotated in a direction to return the sheet to the sheet stacking means, said sheet stacking means When the sheet is rotated in the direction of feeding the sheet, the sheet stacking means rotates at the same speed or faster than the rising speed. Yes.

According to the seventh aspect of the present invention, since the arcuate portion of the guide member rotates at the same speed as the lowering speed of the sheet stacking means or slower than the lowering speed, the sheet is placed on the guide member when the sheet stacking means is lowered. The tip of is not caught. Further, since the guide member rotates at a speed equal to or higher than the rising speed of the sheet stacking unit, the leading edge of the sheet is not caught in the guide member when the sheet stacking unit is lifted.

According to an eighth aspect of the present invention, in the sheet feeding apparatus according to any one of the first to sixth aspects, a variable means for changing a rotating speed of the guide member is provided. It is a feature.

According to the invention described in claim 8 , by changing the rotation speed of the guide member by the variable means, the conveyance speed can be changed depending on the type of the sheet, and the behavior of the leading edge of the sheet can be controlled. Become.

According to a ninth aspect of the present invention, in the sheet supply apparatus according to the eighth aspect of the present invention, when the arcuate portion of the guide member rotates in the direction in which the sheet is fed, It is characterized by controlling it to be slow.

According to the ninth aspect of the present invention, the progress of the sheet can be delayed when the leading edge of the sheet comes close to the press contact portion, and the poor separation that occurs when the leading end of the sheet rushes into the press contact portion is avoided. be able to.

A tenth aspect of the present invention is the sheet supply apparatus according to the fourth or fifth aspect, further comprising an urging unit that pulls the guide member so as to rotate in a direction in which the sheet is fed. A sliding surface that slides when the guide member rotates in the sheet feeding direction and a terminal end of the sliding surface that is engaged with the guide member and rotates the guide member in a direction to return the sheet. And an engaging portion.

According to the tenth aspect of the present invention, the guide member rotates in the direction of feeding the sheet by sliding on the sliding surface of the cam, and the guide member engages with the engaging portion of the cam to thereby change the sheet. Since it rotates in the returning direction, the rotation of the guide member can be realized with a simple mechanism.

According to an eleventh aspect of the present invention, in the sheet feeding apparatus according to the tenth aspect, the guide member is brought into contact with the protrusion provided on the side surface of the guide member by the sliding surface and the engaging portion contacting each other. The sliding surface is formed of a curved concave surface, and the protrusion is moved while sliding on the concave surface, thereby controlling the speed of rotation of the guide member in the feeding direction. It is characterized by that.

According to the eleventh aspect of the present invention, the guide member rotates when the sliding surface and the engaging portion come into contact with the protrusion provided on the side surface of the guide member. The sliding surface is formed of a curved concave surface, and the protrusion is moved while sliding on the concave surface, whereby the speed of rotation of the guide member in the direction of feeding the sheet is controlled. That is, the rotation speed of the guide member can be easily controlled by adjusting the shape of the concave surface of the sliding surface.

A twelfth aspect of the present invention is the sheet supply apparatus according to any one of the first to eleventh aspects, wherein the guide member is upstream of the separation roller in the paper feeding direction before the press contact portion. The pressure contact portion is retracted relative to the paper feed roller relative to the separation member.

According to the twelfth aspect of the invention, since the guide member protrudes upstream of the separation roller in the paper feeding direction before the press contact portion, a dedicated front guide installed before the separation roll becomes unnecessary. Further, the guide member does not interfere with the separation member at the press contact portion.

According to a thirteenth aspect of the present invention, in the sheet feeding apparatus according to any one of the first to twelfth aspects, the separation member is a roller-shaped member, and the guide member is more than the roller-shaped member. Is also characterized by an arc shape having a large curvature.

According to the thirteenth aspect of the present invention, the leading edge of the sheet can be smoothly guided by the guide member formed in an arc shape.

The invention according to claim 14 is the sheet feeding apparatus according to any one of claims 1 to 13 , wherein the guide members are provided on both sides of the separation member. Yes.

According to the fourteenth aspect of the present invention, the sheet can be fed back or returned while preventing the skew of the sheet by the guide member.

According to a fifteenth aspect of the present invention, an image forming apparatus includes the sheet feeding device according to any one of the first to fourteenth aspects.

According to the fifteenth aspect of the present invention, since the sheet supply device according to any one of the first to fourteenth aspects is provided, the sheet is placed at the pressure contact portion between the paper feed roller and the separation member. The sheet is separated by the guide member before entering. For this reason, it is possible to prevent the second and subsequent sheets from entering the downstream side of the press contact portion, and to prevent double feeding of the sheets.

  In the sheet supply apparatus and the image forming apparatus according to the present invention, the sheet is separated by the guide member on the upstream side in the sheet feeding direction from the pressure contact portion between the paper feed roller and the separation member. The sheet can be prevented from entering, and the sheet can be prevented from being double fed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a best mode for carrying out a sheet feeding apparatus according to the invention will be described with reference to the drawings.

  FIG. 1 shows an image forming apparatus 10 including a sheet supply apparatus 50 according to the first embodiment of the present invention.

  The image forming apparatus 10 includes an image forming unit 12 that forms toner images of four colors of yellow, magenta, cyan, and black. In the image forming unit 12, four photosensitive drums 14 are arranged at substantially equal intervals in the vertical direction. Each of the photosensitive drums 14 has a charger 16, a developing device 18, A cleaner 20 is provided. Between the charger 16 and the developing device 18, an image writing device 22 for irradiating the surface of the photosensitive drum 14 with laser light is provided.

  Four transfer rollers 24 are provided on the side opposite to the image writing device 22 of each photosensitive drum 14 so as to face the photosensitive drum 14. A transport belt 26 is wound around the four transfer rollers 24, and the sheet P is transported along the transport belt 26. A sheet P such as a sheet is fed sheet by sheet from a sheet supply device 50 described later or from a sheet tray 44. The sheet P is transported by a pair of transport rollers 28 disposed in the transport path 27, and is transported between the respective photosensitive drums 14 and the transfer rollers 24.

  On the other hand, the surface of each photosensitive drum 14 is charged to a predetermined potential by a charger 16. Then, laser light is irradiated from the image writing device 22 to expose the surface of the photosensitive drum 14 to form an electrostatic latent image. This electrostatic latent image is developed by the developing device 18, and yellow, magenta, cyan, and black toner images are formed on the surfaces of the four photosensitive drums 14. The toner remaining on the surface of the photosensitive drum 14 without being transferred to the sheet P is collected by the cleaner 20.

  The toner image formed on the surface of the photosensitive drum 14 is sequentially transferred onto the sheet P conveyed along the conveying belt 26 by the action of the transfer roller 24 facing the photosensitive drum 14, and four colors are formed on the sheet P. Toner images are superimposed. Thereafter, the toner image on the sheet P is heated and melted by the fixing device 30 installed on the downstream side in the transport direction, and the toner image is fixed on the sheet P. A pair of discharge rollers 32 is provided on the downstream side of the fixing device 30 in the conveyance direction, and the sheet P is conveyed by the discharge rollers 32 and discharged to the discharge tray 34.

  A sheet supply device 50 is disposed on the lower side of the image forming apparatus 10. As shown in FIG. 4, the sheet supply apparatus 50 includes a paper feed tray 52 on which a plurality of sheets P can be stacked. A paper feed roller 54 is disposed obliquely above the paper feed tray 52 on the downstream side in the paper feed direction, and is rotatable in the direction of arrow B about the support shaft 54a. As shown in FIG. 4, the sheets P stacked in the sheet feed tray 52 are pressed against the sheet feed roller 54 by a spring 72 provided at the lower part of the sheet feed tray 52, and the sheet feed roller 54 is pressed onto the upper surface of the sheet P. The uppermost sheet P is sequentially sent out (fed) by rotating in frictional contact therewith.

  As shown in FIG. 4, a separation roller 56 that is pressed against the paper feed roller 54 is disposed below the paper feed roller 54, and the sheet P is pressed at the pressure contact portion A between the paper feed roller 54 and the separation roller 56. Will be asked. As shown in FIG. 2, the sheet feeding roller 54 is provided in the vicinity of the central portion in the longitudinal direction of the sheet feeding device 50. In addition, the separation roller 56 is provided at a position substantially in the center in the longitudinal direction and facing the paper feed roller 54. As shown in FIG. 3, the support shaft 56 a of the separation roller 56 is rotatably supported by frames 57 on both sides formed in the holder 58. The frame 57 has a half-moon shape and is retracted relative to the sheet feeding roller 54 with respect to the separation roller 56, and does not hinder the conveyance of the sheet P and the rotation of the separation roller 56.

  As shown in FIG. 4, cams 60 that rotate integrally with the paper feed roller 54 are provided on both sides of the support shaft 54 a of the paper feed roller 54. The cam 60 can come into contact with a roller 52a protruding from both ends of the paper feed tray 52 by rotation. The paper feed tray 52 is biased upward by a spring 72 and can be moved up and down around a support portion (not shown) on the upstream side in the paper feed direction by rotation of the cam 60. The sheet feed tray 52 presses the sheets P stacked on the sheet feed tray 52 to the sheet feed roller 54 side by the force of the spring 72 (see FIG. 6A). In addition, a guide plate 88 that regulates the front end surface of the lower portion of the stacked sheets P is disposed on the downstream side of the sheet feeding tray 52 in the sheet feeding direction.

  As shown in FIGS. 2 and 4, on both sides of the frame 57 that supports the separation roller 56, the guide plate 88 can be brought into contact with the leading end in the sheet feeding direction of the sheets stacked on the sheet feeding tray 52. A guide member 62 is disposed (see FIGS. 5 and 6). The guide member 62 has a shape that is cut out so as to leave about 2/3 of the cylinder, and includes a circular arc portion 62 a having a larger curvature than the separation roller 56. As shown in FIGS. 2 and 3, each guide member 62 is rotatably supported by the frame 63 on both sides of the support shaft 63 a. The frame 63 is held by a housing (not shown). The frame 63 is in a half-moon shape and is retracted from the guide member 62 with respect to the paper feed roller 56, and does not hinder the conveyance of the sheet P and the rotation of the guide member 62.

  As shown in FIG. 4, when the guide member 62 rotates, the arc portion 62 a protrudes downstream of the separation roller 56 in the paper feeding direction before the pressure contact portion A between the paper feeding roller 54 and the separation roller 56. Further, the arc portion 62 a is retracted (retracted) from the separation roller 56 with respect to the sheet feeding roller 54 at the pressure contact portion A between the sheet feeding roller 54 and the separation roller 56.

  On the downstream side of the two guide members 62 in the sheet feeding direction, cams 66 for rotating the guide members 62 are disposed on both sides. The cam 66 is supported so as to be rotatable about the support shaft 67 in the arrow C direction. The cam 66 includes a peripheral surface portion 66a that is cut out so as to leave about 3/4 of the disk, and the cut-out portion is a curved concave surface 66b. A gear 80 is provided at the axial end of the support shaft 54 a of the paper feed roller 54, and the gear 80 meshes with a gear 82 provided at the axial end of the support shaft 67. A motor (not shown) is connected to the support shaft 54 a, the feed roller 54 is rotated by the motor, a driving force is transmitted to the gear 82 through the gear 80, and the cam 66 is rotated by the rotation of the support shaft 67. . Thus, the sheet feeding roller 54 and the cam 66 can be rotated by one motor. For this reason, driving means such as a dedicated motor for rotating the cam 66 is not required, and the cost can be reduced.

  A cylindrical projection 64 is provided on the side surface of the guide member 62 in the vicinity of the edge on the downstream side in the paper feeding direction of the arc portion 62a, and the peripheral surface 66a and the concave surface 66b of the cam 66 are formed on the projection 64. Abut. One end of a spring 74 is attached to the protrusion 64, and the other end of the spring 74 is attached to a variable device 76 that moves substantially parallel to the biasing direction (in the direction of arrow F) to change the tension of the spring 74. ing. The variable device 76 can be advanced and retracted substantially parallel to the biasing direction of the spring 74 (in the direction of arrow F) by a solenoid (not shown).

  Further, guide plates 84 and 86 for guiding the sheet P to the conveyance roller 28 are arranged on the downstream side of the pressure contact portion between the paper feed roller 54 and the separation roller 56 so as to face each other with the conveyance path 27 for the sheet P interposed therebetween. Has been.

  As shown in FIG. 1, a paper tray 44 is disposed below the image forming apparatus 10. In the paper tray 44, sheets P having a size different from that of the paper feeding tray 52 can be stacked. On the downstream side of the sheet tray 44 in the sheet feeding direction, a sheet feeding roller 46 for feeding the stacked sheets P one by one is disposed. Further, a guide plate 48 that guides the sheet P to the transport roller 28 is disposed on the downstream side of the paper feed roller 46 so as to face the sheet P with a transport path therebetween.

  Next, the operation of the sheet feeding apparatus 50 according to the present invention will be described.

  As shown in FIG. 4, when a sheet is fed from the sheet feed tray 52, the support shaft 54a of the sheet feed roller 54 is rotated in the direction of arrow B by a motor (not shown). Accordingly, the driving force is transmitted to the gear 82 by the rotation of the gear 80 provided on the support shaft 54a, and the cam 66 rotates in the direction of arrow C by the rotation of the support shaft 67.

  When the support shaft 54a rotates from the state shown in FIG. 4, the cam 60 rotates and the contact between the cam 60 and the roller 52a is released. As a result, as shown in FIG. 6B, the paper feed tray 52 is raised by the biasing force of the spring 72, and the upper surface of the sheets P stacked on the paper feed tray 52 is pressed against the paper feed roller 54.

  Further, when the cam 66 rotates in the direction of arrow C from the state shown in FIG. 4, the engagement between the peripheral surface portion 66 a of the cam 66 and the protrusion 64 is released. As a result, as shown in FIG. 6B, the protrusion 64 moves while sliding on the concave surface 66b of the cam 66 by the biasing force of the spring 74, and the guide member 62 feeds the sheet (direction of arrow E). To turn. At that time, the guide member 62 rotates while the arc portion 62 a is in contact with the front end of the sheet P stacked on the paper feed tray 52. By adjusting the shape of the concave surface 66b of the cam 66, the rotation speed of the guide member 62 can be easily controlled.

  Then, as shown in FIG. 6A, when the paper feeding roller 54 rotates in the direction of arrow B, the uppermost sheet P stacked on the paper feeding tray 52 comes into frictional contact with the paper feeding roller 54, and the uppermost sheet P The upper sheet P is sent in the direction of arrow G. At that time, before the sheet P enters the pressure contact portion A between the sheet feeding roller 54 and the separation roller 56, the guide member 62 with which the leading end of the sheet P abuts rotates, so that the uppermost sheet P and the two sheets The subsequent sheets P are easily separated. As a result, the uppermost sheet P and the second and subsequent sheets P are separated before entering the press contact portion A, and the first and second sheets P are rolled at the press contact portion A. That is, in the conventional sheet supply apparatus, when three sheets enter the pressure contact portion between the sheet feeding roller and the separation roller, the effect of blocking the second sheet is reduced. On the other hand, in the sheet supply apparatus 50 according to the present embodiment, since the separation performance of the sheet P is improved by contacting the guide member 62 before the press contact portion A, three or more sheets P enter the press contact portion A. Frequency is reduced. For this reason, it is possible to suppress the second and subsequent sheets P from entering the downstream side of the press contact part A, and it is possible to prevent the sheets P from being double-fed.

  Further, as shown in FIG. 6B, when the sheet feeding tray 52 is raised, the guide member 62 rotates in the direction in which the sheet P is fed, so that the sheet P can be smoothly guided to the press contact portion A.

  Thereafter, when the cam 66 further rotates in the direction of the arrow C from the state shown in FIG. 6B, the protrusion 64 engages with the peripheral surface 66a at the end of the concave surface 66b, and as shown in FIG. The rotation of the cam 66 causes the guide member 62 to rotate in the direction in which the sheet P is returned against the biasing force of the spring 74 (arrow E direction). At this time, the guide member 62 rotates while the arc portion 62 a abuts against the leading end of the sheet P stacked on the sheet feed tray 52, and the sheet P is returned to the sheet feed tray 52.

  As shown in FIG. 4, when the paper feed roller 54 rotates in the direction of arrow B, the cam 60 comes into contact with the roller 52 a and lowers the paper feed tray 52 against the urging force of the spring 72. As a result, as shown in FIG. 5A, when the paper feed tray 52 is lowered, the guide member 62 rotates in a direction to return the sheet P to the paper feed tray 52. That is, when the guide member 62 rotates in the direction of the arrow D and returns the sheet P to the paper feed tray 52, the paper feed tray 52 is lowered, so that the return of the sheet P is not hindered.

  Further, when the size and shape of the peripheral surface portion 66 a and the concave surface 66 b of the cam 66 are adjusted and the shape of the cam 60 is adjusted, the guide member 62 is rotated in a direction to return the sheet P to the paper feed tray 52. Rotates the guide member 62 at the same speed as the lowering speed of the paper feed tray 52 or slower than the lowering speed. Thus, the leading edge of the sheet P is not caught in the guide member 62 when the paper feed tray 52 is lowered. Similarly, the size and shape of the peripheral surface portion 66a and the concave surface 66b of the cam 66 are adjusted, and the guide member 62 is rotated in the direction in which the sheet P is fed by adjusting the shape of the cam 60. The member 62 is rotated at the same speed as the rising speed of the paper feed tray 52 or faster than the rising speed. Thus, the leading edge of the sheet P is not caught in the guide member 62 when the paper feed tray 52 is raised.

  Further, the rotation speed of the guide member 62 is changed by moving the variable device 76 back and forth substantially parallel to the urging direction of the spring 74 (arrow F direction) and changing the tension of the spring 74. By changing the rotation speed of the guide member 62, it is possible to control the traveling speed of the leading edge of the sheet P in the vicinity of the pressure contact portion A between the paper feed roller 54 and the separation roller 56. For example, when the guide member 62 rotates in the direction in which the sheet P is fed, the variable device 76 is advanced in the direction of the cam 66 after the guide member 62 starts to rotate. By the operation of the variable device 76, when the guide member 62 rotates in the direction in which the sheet P is fed, the rotation speed of the guide member 62 can be controlled so as to be later than the initial speed. Accordingly, the progress of the sheet P can be delayed when the leading edge of the sheet P comes close to the pressure contact portion A between the paper feed roller 54 and the separation roller 56, and the leading edge of the sheet P rushes into the pressure contact portion A vigorously. It is possible to avoid the occurrence of poor separation that occurs in Further, by changing the rotation speed of the guide member 62 by the variable device 76, the traveling speed can be changed depending on the type of the sheet P.

  In such a sheet supply device 50, each time the paper feed roller 54 makes one rotation, the paper feed tray 52 rises and the guide member 62 rotates in the direction of feeding the sheet P, and the paper feed tray 52 descends. As a result, the guide member 62 rotates in a direction to return the sheet P to the paper feed tray 52, so that the uppermost sheet P stacked on the paper feed tray 52 is sent out one by one. At this time, since the second and subsequent sheets P are separated before the sheet P enters the press contact portion A by the guide member 62, the separation performance of the sheet P is improved. In addition, the uppermost sheet P is sent out, and the second and subsequent sheets P are returned to the paper feed tray 52 by the rotation of the guide member 62. For this reason, it is possible to prevent the sheet P from being double fed and to stably supply the sheet P.

  Further, since the arc portion 62a of the guide member 62 protrudes downstream of the separation roller 56 in the sheet feeding direction, a front guide plate for regulating the leading edge of the sheet P in the sheet feeding tray 52 is not necessary. Further, since the arc portion 62a of the guide member 62 is larger than the curvature of the separation roller 56 and the arc portion 62a is retracted from the separation roller 56 at the pressure contact portion A, the leading edge of the sheet P can be guided smoothly. Furthermore, the sheet P can be sent out and returned without skew.

  Further, instead of the two-member guide member 62 shown in FIG. 3, as shown in FIG. 7, a one-member guide member 92 may be provided. The guide member 92 has a central portion connected by a connecting portion 93, and a notch 93 a is formed in the connecting portion 93 so as not to interfere with the separation roller 56. In the guide member 92, the support shafts 93a at both ends are rotatably supported by a housing (not shown). By configuring the guide member 92 with one component, positioning and attachment are facilitated.

  Next, a modified example of the sheet feeding apparatus according to the present invention will be described.

  In addition, the same code | symbol is attached | subjected to the member same as the sheet supply apparatus 50 shown in FIG. 4, and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 8A and 8B, instead of the guide member 62 of the sheet feeding apparatus 50 shown in FIG. 4, a plurality of protrusions 104 are formed on the arc portion 102a in a direction perpendicular to the sheet P feeding direction. The guide member 102 is provided. As shown in FIG. 8B, the plurality of protrusions 104 are provided at a plurality of locations at regular intervals along the axial direction of the guide member 102. In this configuration, the second and subsequent sheets P are caught by the protrusions 104 of the guide member 102, so that they are separated from the uppermost sheet P and easily returned to the paper feed tray 52. For this reason, the separation performance of the sheet P can be further improved. Further, the separation performance of the sheet P can be improved without providing a dedicated sheet returning means, which contributes to cost reduction.

  As another modified example, as shown in FIGS. 9A and 9B, instead of the guide member 62 of the sheet feeding apparatus 50 shown in FIG. 4, arcs are formed at a plurality of locations on the circumferential surface of the arc portion 112a. A guide member 112 to which a sheet-like member 114 having a larger frictional force with the sheet P than the portion 112a is bonded is provided. The sheet-like member 114 is made of a material having a large frictional force with the sheet P, such as a resin or rubber sheet-like member. Further, fine unevenness may be formed on the surface of the sheet-like member 114 by surface processing to increase the frictional force with the sheet P.

  In this configuration, the second and subsequent sheets P are separated from the uppermost sheet P by the frictional force with the sheet-like member 114 bonded to the guide member 112 and are easily returned to the paper feed tray 52. For this reason, the separation performance of the sheet P can be further improved. Further, the separation performance of the sheet P can be improved without providing a dedicated sheet returning means, which contributes to cost reduction.

  In the above-described embodiment, the sheet P fed from the paper feed tray 52 is collected at the pressure contact portion A between the paper feed roller 54 and the separation roller 56. However, the present invention is not limited to this configuration. For example, the sheet P may be rolled by pressing the sheet feeding roller and the pad.

  In the above embodiment, the sheet supply device 50 sends out the sheets P stacked in the paper feed tray 52. However, the sheet supply device 50 is arranged on the paper tray 44 of the image forming apparatus 10 shown in FIG. You may set up. Accordingly, when the sheets P stacked on the paper tray 44 are fed, it is possible to prevent the occurrence of double feeding and to stably supply the sheets P.

1 is a schematic configuration diagram illustrating an image forming apparatus including a sheet supply apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view illustrating a sheet feeding roller, a separation roller, and a guide member of the sheet supply apparatus illustrated in FIG. 1. FIG. 2 is an exploded perspective view illustrating a separation roller and a guide member of the sheet supply apparatus illustrated in FIG. 1. FIG. 3 is a configuration diagram illustrating a sheet feeding tray moving mechanism and a guide member rotating mechanism in the sheet supply apparatus illustrated in FIG. 1. FIG. 4 is a configuration diagram illustrating a state of a guide member when returning a sheet to a paper feed tray, and a configuration diagram illustrating a mechanism for rotating the guide member in the sheet return direction. FIG. 4 is a configuration diagram illustrating a state of a guide member when a sheet is fed out from a sheet feeding tray, and a configuration diagram illustrating a mechanism for rotating the guide member in the sheet feeding direction. It is a disassembled perspective view which shows the modification of a guide member. It is the side view and perspective view which show the guide member used with the sheet supply apparatus which concerns on 2nd Embodiment of this invention. It is the side view and perspective view which show the guide member used with the sheet supply apparatus which concerns on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming part 27 Conveying path 28 Conveying roller 50 Sheet supply apparatus 52 Paper feed tray (sheet stacking means)
54 Feed roller 54a Support shaft 56 Separation roller (separation member)
60 Cam 62 Guide member 62a Arc portion 63a Support shaft 64 Projection portion 66 Cam 66b Concave surface (sliding surface)
66a Peripheral surface part (engagement part)
67 Support shaft 72 Spring (sheet stacking means)
74 Spring (biasing means)
76 Variable device 80 Gear 82 Gear 88 Guide plate 102 Guide member 102a Arc part 104 Projection 112 Guide member 112a Arc part 114 Sheet-like member A Pressure contact part P Sheet

Claims (15)

A paper feed roller for feeding out the sheet;
A plurality of sheets can be stacked, and a sheet stacking unit that presses the sheet against the sheet feeding roller;
A separation member that rolls the sheet at a pressure contact portion that is pressed against the paper feed roller;
Includes an arcuate portion that will be abutted against the leading edge of the sheet stacked on said sheet stacking means in the sheet feeding direction upstream side of the press contact portion, and a guide member which is rotatably supported in the circumferential direction of the arcuate portion ,
Have
The arcuate portion rotates in a direction to return a sheet to the sheet stacking unit when the sheet stacking unit descends, and rotates in a direction in which the sheet is fed when the sheet stacking unit rises. Sheet feeding device. The sheet feeding apparatus according to claim 1, wherein a projection is provided on the arc-shaped portion of the guide member so as to be orthogonal to a sheet feeding direction. The sheet feeding apparatus according to claim 1, wherein a sheet member having a larger frictional force with the sheet than the guide member is provided in the arc-shaped portion of the guide member.   The sheet supply device according to any one of claims 1 to 3, wherein the guide member is rotated by a cam rotation.   The sheet feeding apparatus according to claim 4, wherein the cam rotates in conjunction with rotation of the sheet feeding roller.   6. The sheet feeding apparatus according to claim 1, wherein the guide member rotates in conjunction with the movement of the sheet stacking unit. When the arcuate portion of the guide member rotates in a direction to return the sheet to the sheet stacking unit, the arcuate portion rotates at a speed equal to or lower than the descending speed of the sheet stacking unit and feeds the sheet. 2. The sheet feeding apparatus according to claim 1 , wherein the sheet feeding unit rotates at a speed equal to or higher than a rising speed of the sheet stacking unit . The sheet feeding apparatus according to any one of claims 1 to 6, further comprising a variable unit that changes a rotating speed of the guide member . 9. The sheet feeding apparatus according to claim 8 , wherein the variable unit controls the arcuate portion of the guide member so as to be later than the initial speed when the arcuate portion rotates in the sheet feeding direction. . An urging means for pulling the guide member so as to rotate in the sheet feeding direction;
The cam is formed at a sliding surface that slides when the guide member rotates in a sheet feeding direction, and an end of the sliding surface, and is engaged with the guide member to return the sheet in the direction of returning the sheet. The sheet feeding apparatus according to claim 4, further comprising an engaging portion that rotates the member . The guide member rotates when the sliding surface and the engaging portion come into contact with a protrusion provided on a side surface of the guide member,
The sliding surface is formed of a curved concave surface, and the protrusion is moved while sliding on the concave surface, so that a speed of rotation of the guide member in a feeding direction is controlled. The sheet supply apparatus according to claim 10. The guide member according to claim in front of the pressure-contacting portion, characterized in that it is recessed from the projecting the separation roller in the sheet feeding direction upstream side, the separating member relative to the paper feed roller at the pressure contact portion The sheet supply apparatus according to any one of claims 1 to 11 . The separation member is a roller-shaped member,
The sheet feeding apparatus according to any one of claims 1 to 12 , wherein the guide member is formed in an arc shape having a larger curvature than the roller-shaped member . The sheet supply apparatus according to any one of claims 1 to 13 , wherein the guide member is provided on both sides of the separation member . An image forming apparatus comprising the sheet supply device according to claim 1.

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