JP2017100884A - Sheet supply device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the supply rate of sheets.SOLUTION: A sheet supply device 1 has a constant sheet conveyance velocity (V1) between a delivery roller 41 and a conveyance roller 6 while delivering a sheet from a sheet feeding cassette 40 by a contact part 41a of the semicircular delivery roller 41, and makes the sheet conveyance velocity (V2) of the conveyance roller 6 faster when a non-contact part 41b of the delivery roller 41 faces the sheet and the contact part 41a separates from the sheet, thereby preventing damage on the delivery roller 41 and a separation conveyance roller pair 8 by preventing pulling of the sheet by the delivery roller 41 and the conveyance roller 6, preventing reduction in the supply rate of sheets due to the damage, and also increasing the supply rate of sheets by shortening the interval of delivering the sheets by the delivery roller 41 with acceleration of the conveyance velocity of sheets from V1 to V2.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a sheet supply apparatus that supplies sheets and an image forming apparatus that includes the sheet supply apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus such as a printer or a copying machine that forms an image on a sheet sends out the sheets stacked on a cassette by a sheet supply device, and forms an image on the sheet. In this case, the sheet feeding apparatus pushes up the sheet stacked on the stacking plate biased upward, and presses the uppermost sheet against the semicircular portion of the semicircular feeding roller (sending means, rotating member). The sheet is fed by rotation of the feeding roller (Patent Document 1). The sheet feeding device receives the sheet fed by the feeding roller by a pair of conveying rollers on the downstream side in the sheet conveying direction, and conveys the sheet by the feeding roller and the conveying roller pair (conveying means). . The feeding roller feeds the sheet to the pair of conveying rollers, and when the pair of conveying rollers comes to convey the sheet, the semicircular flat portion faces the sheet and stops rotating, and does not convey the sheet. The sheet is conveyed in pairs.

JP-A-6-9079

  However, in recent years, the level of demand for productivity is increasing in image forming apparatuses, and it is necessary to increase the sheet conveyance speed. Therefore, it is conceivable to increase the peripheral speed between the sending roller and the conveying roller pair. However, when the peripheral speed is increased, it becomes difficult to make the peripheral speeds of the feed roller and the transport roller pair the same. If the peripheral speed of the conveying roller pair becomes faster than the peripheral speed of the sending roller, the sheet is pulled between the conveying roller pair and the sending roller, and the sheet and the sending roller are damaged. Or the delivery roller may be worn out. For this reason, it has been difficult for the sheet supply apparatus to increase the number of sheets supplied per unit time (increase the supply rate) without reducing the conveyance performance.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet supply apparatus capable of reducing a decrease in sheet conveyance performance and increasing a supply rate, and an image forming apparatus including the sheet supply apparatus.

  The sheet supply apparatus of the present invention takes a stacking unit on which sheets are stacked, a contact state in contact with the sheets stacked on the stacking unit, and a non-contact state in which the sheets stacked on the stacking unit do not contact, After the sheet is fed out in the contact state, the feeding unit that is in the non-contact state, the conveyance unit that is arranged downstream of the feeding unit in the sheet feeding direction, and that conveys the sheet sent out by the feeding unit, and the sending Driving means for driving the means and the conveying means, and the conveying means conveys the sheet at a first conveying speed when the sending means is in the contact state, and the conveying means when the sending means is in the non-contact state. Transmitting means for transmitting the driving force of the driving means to the conveying means so that the sheet is conveyed at a second conveying speed higher than the first conveying speed. It is a symptom.

  An image forming apparatus according to the present invention includes the above-described sheet supply device, and an image forming unit that forms an image on the sheet supplied by the sheet supply device.

  The sheet supply apparatus of the present invention can increase the sheet supply rate without damaging the sheet or reducing the conveyance performance.

  Since the image forming apparatus of the present invention includes the sheet supply apparatus that increases the sheet supply rate, the productivity of forming an image on a sheet can be improved.

2 is a schematic cross-sectional view of the image forming apparatus according to the embodiment of the present invention along the sheet conveyance direction. It is sectional drawing along the sheet conveyance direction of the sheet supply apparatus of 1st Embodiment of this invention. FIG. 3 is an external perspective view of the paper feed cassette of FIG. 2. FIG. 6 is a plan view in which a driving unit of the sheet supply apparatus is developed. It is operation | movement explanatory drawing of the rotation transmission mechanism in the drive part of FIG. (A) is a figure which shows the initial position of each gear of a rotation transmission mechanism. (B) is the figure which the small diameter sector gear began to mesh with the large diameter gear. (C) is the figure which the large diameter sector gear began to mesh with the small diameter gear. It is explanatory drawing of the operation | movement which sends out the sheet | seat in the sheet supply apparatus of FIG. (A) is a figure of an initial state. FIG. 7B is a diagram in which the sheet feeding operation is started. FIG. 6C is a diagram in which a sheet is conveyed by a delivery roller and a separation conveyance roller pair. FIG. 4D is a diagram in which a sheet is conveyed by a pair of separation conveyance rollers. 2 is a schematic control block diagram for controlling the image forming apparatus. FIG. It is a figure which shows the relationship between the sheet conveyance speed of a sending roller, and the sheet conveyance speed of a separation conveyance roller pair. It is a top view of the sheet supply apparatus of 2nd Embodiment, and is a figure equivalent to FIG. FIG. 10 is a control block diagram of the sheet supply apparatus of FIG. 9. 10 is a flowchart for explaining the operation of the sheet supply apparatus of FIG. 9.

  Hereinafter, a sheet supply apparatus according to an embodiment of the present invention and an image forming apparatus according to an embodiment of the present invention including the sheet supply apparatus will be described with reference to the drawings.

(Image forming device)
FIG. 1 is a schematic cross-sectional view along the sheet conveying direction of an image forming apparatus 900 according to an embodiment of the present invention. The image forming apparatus 900 includes an image reading apparatus 901 that reads an original on the upper part of the apparatus main body 900A.

  In the image reading apparatus 901, the user presses the document pressing plate 904 and places the document D on the document table glass 906 with the image surface facing down. Then, the original cover 904 is closed by the user. The document pressing plate 904 presses the document D against the document table glass 906. An operation button or the like on an operation panel (not shown) is pressed by the user. Then, the image reading unit 908 moves rightward in FIG. 1 and reads the document D on the document table glass 906. Finally, the image reading apparatus 901 converts the read document image into a digital signal by a converter (not shown) and transmits the digital signal to the laser scanner 910.

  The signal transmitted to the laser scanner 910 is converted into a laser beam and irradiated to the photosensitive drum 912 via the scanner mirror 910a and the folding mirror 910b that rotate at high speed. The photosensitive drum 912 is uniformly charged by the charger 914, and an electrostatic latent image is formed on the portion irradiated with the laser light. The electrostatic latent image is developed by the toner developer supplied from the developing roller 916 and becomes a visible toner image.

  On the other hand, a sheet is conveyed from the sheet feeding cassette 40 in the direction of arrow E (sheet conveyance direction) by a semicircular delivery roller 41, and a photosensitive drum 912 and a transfer roller 924 are separated by a separation conveyance roller pair 8 and a registration roller pair 9. It is conveyed between. The transfer roller 924 transfers the toner image on the photosensitive drum 912 to the conveyed sheet. The sheet on which the toner image is transferred is conveyed to the fixing device 928 by the conveying device 926. The fixing device 928 heats and presses the sheet with the fixing roller 928a and the pressure roller 928b to fix the toner image on the sheet. The sheet on which the toner image is fixed is discharged to a discharge tray 932 by a discharge roller pair 930.

  In the above configuration, the charger 914, the photosensitive drum 912, and the like are detachably attached to the apparatus main body 900A as the process cartridge 138. The process cartridge 138, the transfer roller 924, and the like form an image forming unit 939 that forms an image on a sheet.

  The image forming apparatus 900 described above operates under the control of the CPU 30 shown in FIG. FIG. 7 is a schematic control block diagram for controlling the image forming apparatus 900. The CPU 30 controls a feeding motor M1 (described later), a fixing motor M4, a solenoid SL1 (described later), and the like. The RAM 31 is a work area for the CPU 30 and a temporary storage area for data. In the ROM 32, a firmware program for controlling the image forming apparatus and a boot program for controlling the firmware program are written and used by the CPU 30. The counter 33 counts the number of rotations of the feeding motor M1. The communication I / F 34 is connected to an external computer or the like, and transfers image data or the like via this.

(Sheet feeding apparatus 1 of the first embodiment)
FIG. 2 is a cross-sectional view taken along the sheet conveying direction of the sheet feeding apparatus 1 according to the first embodiment of the present invention. FIG. 3 is an external perspective view of the paper feed cassette 40 of FIG.

  The sheet supply apparatus 1 includes a paper feed cassette 40, a semicircular feed roller 41, a separation conveyance roller pair 8, a drive unit 23, and the like. The sheet conveying direction is the direction of arrow E described in FIGS. The upstream in the sheet conveying direction is the left side in the direction of arrow E, and is the rear end side of the sheet. Further, the downstream in the sheet conveying direction is the right side, which is the front end side of the sheet.

  A box-shaped sheet feeding cassette 40 as a stacking unit on which sheets are stacked is provided with a mounting plate 2 on which a sheet P is mounted by a user. The placement plate 2 is rotatably provided at a rotation fulcrum 2a provided on the upstream side with respect to the sheet conveyance direction E of the paper feed cassette 40 so that the front end portion 2b on the downstream side in the sheet conveyance direction moves up and down. It has become. A mounting plate pressing spring 3 is provided between the bottom plate 40 a of the paper feed cassette 40 and the tip portion 2 b of the mounting plate 2. The mounting plate pressing spring 3 pushes up the tip 2b of the mounting plate 2. Although the compression coil spring is used for the mounting plate pressing spring 3, a plate spring, rubber or the like may be used. A rear end regulating plate 4 is detachably mounted on the mounting plate 2. The rear end regulating plate 4 can change the mounting position according to the size of the sheet P by selecting and inserting a plurality of holes 2 c formed in the mounting plate 2. Separating claws 5 for restricting the upper surface of the stacked sheets P are provided at both corners of the upper end of the upstream end of the sheet feeding cassette 40, respectively. The separation claw 5 is provided in order to feed sheets one by one from the sheet feeding cassette 40.

  A semicircular delivery roller 41 as a delivery means and a rotation member is rotatably disposed on the apparatus main body 900 </ b> A so as to face the downstream end of the sheet feeding cassette 40 in the sheet conveyance direction. The delivery roller 41 is formed with a semicircular contact portion 41a that contacts a sheet stacked on the paper feed cassette 40 and a flat non-contact portion 41b that does not contact the sheet in the outer peripheral rotation direction. The feeding roller 41 is configured to contact and feed out the uppermost sheet among the sheets placed on the placing plate 2 at the contact portion 41a.

  The separating and conveying roller pair 8 as a conveying means and a conveying roller pair is arranged downstream of the sending roller 41 in the sheet conveying direction, and the separating and conveying roller pair 8 is constituted by a conveying roller 6 and a separating roller 7 that are in pressure contact with each other. Has been. The conveyance roller 6 and the separation roller 7 sandwich the sheet and rotate (clamp rotation) to convey the sheet. When the sheets sent out from the paper feed cassette 40 by the delivery roller 41 overlap, the separation transport roller pair 8 becomes a transport load of the lower sheet on which the lower separation roller 7 overlaps, and the upper transport roller pair 8 The conveyance roller 6 conveys one upper sheet. The separation claw 5 provided in the paper feed cassette 40 can also separate and feed the sheets one by one. Therefore, instead of the separation conveyance roller pair 8, a roller pair for simply conveying the sheet is provided. May be.

  Next, a driving unit for increasing the sheet supply rate, which is a feature of the sheet supply apparatus 1, will be described. FIG. 4 is a plan view in which the drive unit 23 of the sheet supply apparatus 1 is developed. The drive unit 23 as drive means drives (rotates) the semicircular feed roller 41 and the transport roller 6 of the separation transport roller pair 8 by a common feed motor M1.

  The drive unit 23 is provided between the feed motor M1 as a drive source for rotating the feed roller 41 and the transport roller 6, and between the feed motor M1 and the transport roller 6, and uses the rotational driving force of the feed motor M1. A rotation transmission mechanism 24 that transmits (can transmit) to the conveyance roller 6 is provided. Further, the drive unit 23 includes a gear train 25 that transmits the rotation of the feed motor M1 to the feed roller 41, a solenoid SL1, and the like.

  The gear train 25 includes a drive gear 26 provided in the feed motor M1, a first intermediate gear 27, a second intermediate gear 28, a third intermediate gear 29, a driven gear 30 provided on the rotation shaft 42 of the feed roller 41, and the like. It consists of The first intermediate gear 27 meshes with the drive gear 26 and the second intermediate gear 28. The second intermediate gear 28 and the third intermediate gear 29 are integrally provided on a common rotating shaft 31. The rotation shaft 31 is rotatably provided on the apparatus main body 100A. Therefore, the gear train 25 applies the rotational force of the feeding motor M1 to the rotation shaft via the drive gear 26, the first intermediate gear 27, the second intermediate gear 28, the rotation shaft 31, the third intermediate gear 29, and the driven gear 30. 42, the feed roller 41 is rotated.

  The rotation transmission mechanism 24 includes a drive gear 26, a first intermediate gear 27, a second intermediate gear 28, a small-diameter sector gear 14, a large-diameter sector gear 15, a large-diameter gear 11 and a small-diameter gear 12 provided in the feeding motor M1. It consists of The second intermediate gear 28, the small-diameter sector gear 14 and the large-diameter sector gear 15 as the conveyance control gear 13 are integrally provided on a common rotating shaft 31. The large-diameter gear 11 and the small-diameter gear 12 that are the conveyance drive stage gears 10 are integrally provided on the rotation shaft 21 of the conveyance roller 6. The small diameter sector gear 14 meshes with the large diameter gear 11. The large-diameter sector gear 15 is adapted to mesh with the small-diameter gear 12.

  In FIG. 5A described later, the radius r1 and the central angle α1 of the small-diameter sector gear 14 are set smaller than the radius r2 and the central angle α2 of the large-diameter sector gear 15 (r1 <r2, α1 <α2). ). The central angle α4 formed by the end portion 15b in the rotation direction M of the large-diameter sector gear 15 and the start end portion 14a in the rotation direction M of the small-diameter sector gear 14 is equal to the start end portion 15a in the rotation direction M of the large-diameter sector gear 15 and the small-diameter sector shape. It is set to be larger than the central angle α3 formed with the terminal portion 14b in the rotational direction M of the gear 14. That is, α4> α3 is set. Therefore, the toothless portion 16 between the end portion 15b of the large-diameter sector gear 15 and the start end portion 14a of the small-diameter sector gear 14 has a start end portion 15a of the large-diameter sector gear 15 and an end portion 14b of the small-diameter sector gear 14. It is set wider than the missing tooth portion 17 between the two.

  The solenoid SL1 operates the second intermediate gear 28 so that the small-diameter sector gear 14 and the large-diameter sector gear 15 rotate only once by the rotation of the feeding motor M1 rotating at a constant speed. ing.

  Next, based on the configuration described above, the operation of the sheet supply apparatus 1 will be described with reference to FIGS.

  FIG. 5 is an operation explanatory view of the rotation transmission mechanism 24 in the drive unit 23 of FIG. In FIG. 5A, the small-diameter sector gear 14 and the large-diameter sector gear 15 rotate in the arrow M direction, and the large-diameter gear 11 and the small-diameter gear 12 rotate in the arrow N direction. FIG. 15 is a diagram showing the initial position of each gear immediately after 15 is disengaged from the small-diameter gear 12. In FIG. 5B, the starting end portion 14a of the small-diameter sector gear 14 begins to mesh with the large-diameter gear 11, the large-diameter gear 11 and the rotating shaft 21 rotate, and the conveying roller 6 of the separation conveying roller pair 8 rotates. FIG. FIG. 5C is a view in which the small-diameter sector gear 14 is separated from the large-diameter gear 11 and the large-diameter sector gear 15 starts to mesh with the small-diameter gear 12. FIG. 6 is a diagram for explaining the operation of the sheet feeding apparatus 1 of FIG. FIG. 6A is a diagram of an initial state. FIG. 6B is a diagram in which the sheet feeding operation is started. FIG. 6C is a diagram in which the sheet is conveyed by the feed roller 41 and the separation conveyance roller pair 8. FIG. 6D is a diagram in which the sheet is conveyed by the separation conveyance roller pair 8. FIG. 7 is a schematic control block diagram for controlling the image forming apparatus. FIG. 8 is a diagram illustrating the relationship between the sheet conveyance speed of the delivery roller 41 and the sheet conveyance speed of the separation conveyance roller pair 8.

  The CPU 30 rotates the feeding motor M1. However, the CPU 30 does not turn on the solenoid SL1 in FIG. For this reason, even if the drive gear 26, the first intermediate gear 27, and the second intermediate gear 28 rotate, the rotation of the second intermediate gear 28 is not transmitted to the rotating shaft 31, and the feed roller 41 and the transport roller 6 are It is not rotating. For this reason, as shown in FIG. 6A, the semicircular delivery roller 41 stops rotating with the non-contact portion 41b facing the sheet P. In this state, the placement plate pressing spring 3 pushes up the placement plate 2 and pushes up the sheet P placed on the placement plate 2. Separation claws 5 (FIG. 3) provided at both corners of the downstream end of the sheet feeding cassette 40 in the sheet conveying direction receive both corners of the topmost sheet. Further, as shown in FIG. 5A, the end portion 15b of the large-diameter sector gear 15 faces the small-diameter gear 12, and the large-diameter sector gear 15 and the small-diameter gear 12 are not meshed with each other. For this reason, the conveyance roller 6 has stopped rotating.

  In this state, the CPU 30 turns on the solenoid SL1 for T1 seconds (FIG. 8). Then, the second intermediate gear 28 and the rotary shaft 31 rotate integrally, and the rotational force of the feed motor M1 is changed to the drive gear 26, the first intermediate gear 27, the second intermediate gear 28, the rotary shaft 31, This is transmitted to the rotating shaft 42 via the second intermediate gear 29 and the driven gear 30. As a result, the feed roller 41 rotates from the state of FIG. 6A in the direction of arrow Q as shown in FIG. A DC motor, a stepping motor, or the like is used as the feeding motor M1.

  On the other hand, when the rotating shaft 31 rotates, the small-diameter sector gear 14 and the large-diameter sector gear 15 integrally rotate in the arrow M direction from the state of FIG. Even if the small-diameter sector gear 14 and the large-diameter sector gear 15 rotate in the direction of the arrow M, the toothless portion 16 faces the large-diameter gear 11 and the small-diameter gear 12, so that the rotational force is applied to the large-diameter gear 11 and the small-diameter gear 12. Not communicate. For this reason, although the small diameter sector gear 14 and the large diameter sector gear 15 are rotating, the conveyance roller 6 is not rotating.

  In this way, the transport roller 6 does not rotate, but the delivery roller 41 rotates. Then, as shown in FIG. 6B, the feeding roller 41 contacts the uppermost sheet P at the contact portion 41a, and feeds the uppermost sheet from the sheet feeding cassette 40 (sheet feeding direction). Then, a conveying force is applied in the sheet conveying direction E). The uppermost sheet is pushed and is sent out from the paper feed cassette 40. However, both corners of the leading edge of the sheet are caught by the separation claw 5. For this reason, as shown to (B) of FIG. 6, the front-end | tip part of the sheet | seat P curves and rises.

  Since the rotation of the feeding motor M1 continues, the feeding roller 41 still applies a conveying force to the uppermost sheet. When the sheet is curved and raised to some extent, the sheet comes off the separation claw 5 and returns to a straight state. The uppermost sheet is separated from the sheet overlapping the lowermost sheet and begins to be fed out from the sheet feeding cassette 40. The time at this time is time T2 after the feed motor M1 starts rotating in FIG.

  As shown in FIG. 5B, the delivery roller 41 sends out the sheet from the sheet feeding cassette 40, and until the leading edge of the sheet reaches the separating and conveying roller pair 8 (FIG. 8, time T3), the small diameter. The starting end portion 14 a of the sector gear 14 starts to mesh with the large-diameter gear 11. The large-diameter gear 11 and the rotation shaft 21 rotate, and the conveyance roller 6 of the separation conveyance roller pair 8 starts to rotate. Then, as shown in FIG. 6C, the sheet is fed into the nip of the separation conveyance roller pair 8 by the sending roller 41. The delivery roller 41 and the separation conveyance roller pair 8 convey the sheet at the same sheet conveyance speed (constant speed) V1. Since the sheet conveyance speeds of the delivery roller 41 and the separation conveyance roller pair 8 are the same, the sheet is conveyed without being loosened or pulled and torn.

  Then, as shown in FIG. 6D, the feed roller 41 that has continued to rotate in the direction of the arrow Q starts to face the sheet at the non-contact portion 41b and feeds it from the paper feed cassette 40 until now. It leaves | separates from the sheet | seat which it was (FIG. 8, time T4). Then, as shown in FIG. 5C, the small-diameter sector gear 14 is separated from the large-diameter gear 11, and the large-diameter sector gear 15 is engaged with the small-diameter gear 12. The rotation of the conveying roller 6 is accelerated, and the sheet conveying speed of the separation conveying roller pair 8 is increased from V1 to V2 (> V1). At this time, since the portion of the non-contact portion 41b of the sending roller 41 faces the sheet, the sheet is conveyed at the sheet conveying speed V2 without receiving the conveying resistance of the sending roller 41.

  However, if the sheet conveyance speed of the separation conveyance roller pair 8 increases from V1 to V2 (> V1) in a state where the sheet is conveyed across the delivery roller 41 and the separation conveyance roller pair 8, there is a possibility that the sheets may be pulled together. is there. Therefore, in FIG. 5C, when the small-diameter sector gear 14 is separated from the large-diameter gear 11 and the large-diameter sector gear 15 meshes with the small-diameter gear 12, the missing gear portion 17 causes the large-diameter gear 11 and the small-diameter gear 12 to be engaged. Is in a rotatable state without meshing with any gear. During this time, even if the delivery roller 41 is transporting a sheet, the separation transport roller pair 8 is not transporting the sheet, so that the possibility of pulling the sheets can be prevented.

  Further, as shown in FIG. 6D, when the separation and conveyance roller pair 8 starts conveying the sheet, the sheets are conveyed to the separation and conveyance roller pair 8 without being separated by the separation claw 5. May be. In such a case, the separating and conveying roller pair 8 separates the overlapping sheets by the load of the separating roller 7 and conveys only the uppermost sheet to the downstream registration roller pair 9.

  The feed motor M1 continues to rotate. Therefore, the feed roller 41 rotates from the state of FIG. 6D to the state of FIG. 6A, and the large-diameter fan gear 15 continues to mesh with the small-diameter gear 12 as shown in FIG. (C) of FIG. 5 to the state of FIG. 5 (A). This completes the conveyance of the first sheet (FIG. 8, time T5). The CPU 30 determines whether or not the first sheet has been conveyed based on the number of rotations of the feeding motor M1. When there is continuous sheet feeding, the CPU 30 again activates the solenoid SL1 to transmit the rotation of the feeding motor M1 to the feeding roller 41 and the separation conveying roller pair 8. If there is no sheet to be continuously sent out, the rotation of the feed motor M1 is stopped. The feed roller 41 stops with the non-contact portion 41b facing the sheet. That is, the feeding roller 41 is configured so that the non-contact portion 41b faces the sheet on the sheet feeding cassette and does not contact the sheet from the feeding position where the contact portion 41a contacts the sheet on the sheet feeding cassette 40 and feeds the sheet. It is designed to stop by rotating to the contact position.

  As described above, in the sheet feeding apparatus 1 according to the first embodiment, while the non-contact portion 41b of the feeding roller 41 faces the sheet, the rotation conveying mechanism 24 increases the sheet conveying speed by the separation conveying roller pair 8. You can do that. For this reason, even if the sheet feeding speed of the separation / conveying roller pair 8 is increased from V1 to V2, the sheet feeding apparatus 1 does not cause the sheet conveyance failure or pulling and does not cause separation and conveyance. It is possible to prevent the roller pair 8 from being damaged. It is possible to prevent a decrease in the sheet supply rate due to scratches on the feed roller 41 and the separation conveyance roller pair 8. Further, the sheet supply device 1 shortens the interval at which the feeding roller 41 sends out the sheet by increasing the sheet conveying speed of the separation conveying roller pair 8 from the first conveying speed V1 to the second conveying speed V2. The sheet supply rate can be increased.

  In addition, the image forming apparatus of the present invention includes the sheet supply apparatus 1 with an increased sheet supply rate, so that productivity can be improved.

(Sheet feeding apparatus 101 of the second embodiment)
The sheet feeding apparatus 1 according to the first embodiment described above is configured to rotate the feeding roller 41 and the separation conveyance roller pair 8 by a common feeding motor M1, but the sheet feeding apparatus 101 according to the second embodiment is These are rotated by separate delivery motor M2 and conveyance motor M3.

  FIG. 9 is a plan view of the drive unit 123 of the sheet feeding apparatus 101 according to the second embodiment. FIG. 10 is a control block diagram of the sheet supply apparatus 101 of FIG. FIG. 11 is a flowchart for explaining the operation of the sheet supply apparatus 101 of FIG. Note that the paper feed cassette is the same as the paper feed cassette in the sheet supply apparatus of the first embodiment, and is not shown. Further, since the semicircular feeding roller and separation / conveying roller pair have the same shape as the sheet feeding apparatus of the first embodiment, the same reference numerals are given and the description thereof is omitted.

  In FIG. 9, a semicircular delivery roller 41 as a delivery rotator is rotated by a delivery motor M2 as a first drive source. The rotation of the delivery motor M2 and the delivery roller 41 is transmitted by a pair of intermediate gears 102 and 103. The rotation transmission between the feed motor M2 and the intermediate gear 102 is performed by the operation of the solenoid SL2. The separation conveyance roller pair 8 as a conveyance means is rotated by a conveyance motor M3 as a second drive source via a gear box 104. In the above configuration, the feed motor M2, the pair of intermediate gears 102 and 103, the solenoid SL2, the transport motor M3, and the like constitute a drive unit 123 as drive means.

  In FIG. 10, the CPU 130 controls the sending motor M2, the conveying motor M3, the solenoid SL2, and the like of the image forming apparatus 900. The RAM 131 is a work area for the CPU 130 and a temporary storage area for data. The ROM 132 is written with a firmware program for controlling the image forming apparatus and a boot program for controlling the firmware program, and is used by the CPU 130. The counter 133 counts the rotation time of the delivery roller 41. The communication I / F 134 is connected to an external computer or the like and transfers image data or the like via the computer. A DC motor, a stepping motor, or the like is used for the feed motor M2 and the transport motor M3.

  The operation of the sheet supply apparatus 101 according to the second embodiment will be described. In FIG. 11, the CPU 130 rotates the delivery motor M2 (S201). However, the CPU 130 does not turn on the solenoid SL2. For this reason, the rotation of the delivery motor M2 is not transmitted to the intermediate gear 102, and the delivery roller 41 is not rotating. At this time, the rotation speed of the feed motor M2 is set to a rotation speed at which the sheet conveyance speed of the feed roller 41 becomes V1 when the rotation is transmitted to the feed roller 41.

  In this state, the CPU 130 turns on the solenoid SL2 for a time T1 seconds (S202). Then, the rotational force of the sending motor M2 is transmitted to the sending roller 41 by the pair of intermediate gears 102 and 103, and the sending roller 41 rotates. The delivery roller 41 sends out the sheet from the paper feed cassette. And CPU130 rotates the conveyance roller 6 of the separation conveyance roller pair 8 by rotating the conveyance motor M3 (S203). At this time, the CPU 130 controls the rotation of the feeding motor M2 and the conveying motor M3 so that the sheet conveying speed of the feeding roller 41 and the sheet conveying speed of the conveying roller 6 become the same sheet conveying speed V1.

  The CPU 130 counts the rotation time of the delivery roller 41 by the counter 133, and determines that the non-contact portion 41b of the delivery roller 41 faces the sheet when a predetermined rotation time has elapsed (YES in S204). Then, the CPU 130 increases the rotation of the conveyance motor M3 so that the sheet conveyance speed of the pair of separation conveyance rollers 8 becomes V2 (S205). The delivery roller 41 is in a state in which no sheet is conveyed, and the conveyance roller 6 conveys the sheet at a sheet conveyance speed V2 (> V1) that is faster than the sheet conveyance speed V1. When the conveyance roller 6 conveys the sheet for a predetermined time at the sheet conveyance speed V2, the CPU 130 stops the rotation of the conveyance motor M3 assuming that the sheet has been sufficiently conveyed (S206). When there is continuous sheet feeding (YES in S207), the CPU 30 operates the solenoid SL2 again for T1 seconds to transmit the rotation of the feeding motor M2 to the feeding roller 41. If there is no sheet to be continuously sent out (NO in S207), the rotation of the sending motor M2 is stopped (S208). At this time, the feeding roller 41 stops with the non-contact portion 41b facing the sheet.

  As described above, also in the sheet supply apparatus 101 of the second embodiment, the sheet conveyance speed by the separation conveyance roller pair 8 is increased by the conveyance motor M3 while the non-contact portion 41b of the delivery roller 41 faces the sheet. It can be done. For this reason, even if the sheet conveying speed of the separating / conveying roller pair 8 is increased from V1 to V2, the sheet feeding apparatus 101 does not cause poor sheet conveyance or pulling, and the separating roller / pair 8 And can be prevented from being damaged. It is possible to prevent a decrease in the sheet supply rate due to scratches on the feed roller 41 and the separation conveyance roller pair 8. Further, the sheet supply apparatus 101 can increase the sheet conveyance speed of the separation conveyance roller pair 8 from V1 to V2, thereby reducing the interval at which the feeding roller 41 sends out the sheet, and the sheet supply rate. Can be increased.

  In the sheet supply apparatus 101 according to the second embodiment, the feeding roller 41 and the separation conveying roller pair 8 are rotated by separate motors. For this reason, in the sheet supply apparatus 101, when the non-contact portion 41b of the delivery roller 41 faces the sheet and the conveyance roller 6 is conveying at the sheet conveyance speed V2, the rotation speed of the conveyance roller 6 is set to the sheet conveyance speed V1. It can be rotated faster than the rotation speed. As a result, as soon as the trailing edge of the sheet being conveyed by the conveying roller 6 at the sheet conveying speed V2 passes the feeding roller 41, the feeding roller 41 is immediately moved to a rotation position where the subsequent sheet can be conveyed by the contact portion 41a of the feeding roller 41. Can be kept waiting. Therefore, the sheet interval can be reduced, and the sheet supply rate can be further increased.

  Furthermore, the sheet supply apparatus 101 of the second embodiment can supply sheets of various lengths by controlling the rotation angle and the number of rotations of the transport motor M3 with the feeding motor M2 stopped.

  Since the image forming apparatus of the present invention includes the sheet supply apparatus 1 with an increased sheet supply rate, productivity for forming an image on a sheet can be improved.

  In the above embodiment, the delivery roller 41 has a semicircular shape. However, the shape is not limited to this shape as long as it does not always contact the sheet placed on the placement plate 2.

  Further, even if the separation conveyance roller pair 8 is set to a sheet conveyance speed faster than that of the delivery roller 41, the separation conveyance roller pair 8 is not necessarily equal to the delivery roller 41 as long as the sheet and the separation conveyance roller pair 8 are not damaged. The conveyance speed V1 may not be set. If the sheet conveyance speed of the delivery roller 41 is V1a and the sheet conveyance speed of the separation conveyance roller pair 8 is V1b (> V1a), the delivery roller 41 is not in contact with the sheet on the placement plate 2. In addition, the sheet conveying speed of the separation conveying roller pair 8 is set to V2, which is faster than V1b. Even if it does in this way, the supply rate of a sheet | seat increases more and productivity can be improved.

1, 101: Sheet feeding device, 6: Conveying roller, 7: Separating roller, 8: Separating conveying roller pair (conveying means, conveying roller pair), 11: Large diameter gear, 12: Small diameter gear, 14: Small diameter fan gear, 15: Large-diameter fan gear, 23: Drive unit (drive means), 24: Rotation transmission mechanism, 25: Gear train, 40: Paper feed cassette (stacking means), 41: Semi-circular delivery roller (sending means, rotation) Member), 41a: contact part, 41b: non-contact part, 123: drive part (drive means), 900: image forming apparatus, 900A: apparatus main body of the image forming apparatus, 939: image forming part, E: sheet conveyance direction ( Sheet feeding direction), P: sheet, M1: feeding motor (driving source), M2: feeding motor (first driving source), M3: conveying motor (second driving source), V1: first conveying speed. , V2: second transport speed.

Claims (8)

A stacking means on which sheets are stacked;
A contact state that contacts a sheet stacked on the stacking unit and a non-contact state that does not contact the sheet stacked on the stacking unit, and after the sheet is sent out in the contact state, the non-contact state is transmitted. Means,
A conveying means arranged downstream of the sending means in the sheet sending direction and for conveying a sheet sent by the sending means;
Drive means for driving the delivery means and the transport means;
The conveying means conveys the sheet at a first conveying speed when the sending means is in the contact state, and the conveying means is faster than the first conveying speed when the sending means is in the non-contact state. Transmission means for transmitting the driving force of the driving means to the conveying means so as to convey the sheet at a conveying speed;
A sheet feeding apparatus characterized by the above. The delivery means is movable between a contact position that comes into contact with the sheets stacked on the stacking means and a non-contact position that comes into contact with the sheets that do not contact the sheets.
The sheet feeding apparatus according to claim 1, wherein The sending means has a contact portion that contacts a sheet stacked on the stacking means, and a non-contact portion that does not contact the sheet stacked on the stacking means, and after the sheet is sent out by the contact portion, The non-contact portion faces the sheet and does not contact the sheet;
The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus. The delivery means has a rotating member provided with the contact portion and the non-contact portion in the outer peripheral rotation direction,
The driving unit is configured so that the non-contact portion faces the sheet stacked on the stacking unit from a sending position where the rotating member contacts the sheet stacked on the stacking unit by the contact unit and feeds the sheet. Rotationally driven to a non-contact position that does not contact the sheet
The sheet feeding apparatus according to claim 3, wherein The transmission means is configured so that the conveying means returns from the second conveying speed to the first conveying speed while the driving means rotates the rotating member once. Configured to be synchronized,
The sheet feeding apparatus according to claim 4, wherein The driving means drives the sending means and the conveying means at the first conveying speed when the sending means is in the contact state;
The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus. The delivery means has a delivery roller;
The transport means has a pair of transport rollers for transporting the sheet while sandwiching the sheet,
The transmission means is configured such that the sheet conveying speed of the pair of conveying rollers is the first conveying speed in the contact state where the feeding roller is in contact with the sheet, and the feeding roller is not in contact with the sheet. The driving force of the driving means can be transmitted to the pair of transport rollers so as to be the second transport speed in a contact state;
The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus. A sheet feeding device according to any one of claims 1 to 7,
An image forming unit that forms an image on the sheet supplied by the sheet supply device,
An image forming apparatus.

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