JP2008024520A - Paper carrying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an unpleasant sound generated from a paper feeder. <P>SOLUTION: This paper carrying device has paper feeding rollers 14 and 22 storing paper and carrying the paper, and register roller pairs 16 carrying the paper carried from the paper feeding rollers 14 and 22, and starts the carrying of the paper again in predetermined timing, after imparting deflection, by making the paper abut against these register roller pairs 16, and has guide members 40 and 43 in a deflection forming part of the paper. The guide members 40 and 43 have milers 41, 42, 44 and 45 of a plurality of elastic bodies. The tip of one of the milers 42 and 45 contacts with the belly of the other milers 41 and 44 at a predetermined angle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus applied to an electrophotographic copying machine, a printer, a facsimile, and the like.

  In an image forming unit of an image forming apparatus such as an electrophotographic copying machine, a printer, or a facsimile machine, a toner image formed on a photosensitive member is transferred onto a transfer sheet by a transfer device and then fixed and externally mounted. To be discharged. For example, as shown in FIG. 18, the transfer paper is fed from the paper feed tray, passes through the paper feed rollers 101 and 103, and temporarily stops in a state where the leading end abuts against the registration roller pair 105 in front of the transfer device, The registration roller pair 105 is driven in accordance with the timing of the toner image on the photoconductor 107 to feed the transfer paper to the transfer position.

  However, the collision sound when the leading edge of the transfer paper hits the registration roller pair is greatly disturbing. For example, in Patent Document 1, the speed at which the transfer paper collides with the registration roller pair is slowed down, and the registration roller pair stopped. The noise generated when the transfer paper collides with the paper is reduced.

In addition, noise was generated when the transfer paper was transported to the image forming unit by driving the registration roller pair from a state where the transfer paper was waiting on the registration roller pair. That is, as shown in FIGS. 19 and 20, since the driving of the paper feed roller pair gripping the rear end portion of the transfer paper is sequentially stopped to prevent the double feeding of the paper, when the registration roller pair is driven, Sound was generated when the deflection of the transfer paper was suddenly extended.
JP-A-9-175893

  In addition, if the registration roller pair and the roller gripping the transfer paper are driven at the same time when the transfer paper is re-conveyed, sudden tension of the paper can be prevented. The roller that grips the transfer paper rotates faster than the transfer paper, and even if it is driven to rotate at the same time, the trailing edge of the transfer paper is conveyed at a higher speed, resulting in increased deflection and jamming. There was a problem.

  An object of the present invention is to prevent an unpleasant sound generated from a sheet feeding device.

  The invention according to claim 1 includes a paper feeding unit that accommodates the paper and conveys the paper, and a registration roller adjustment unit that conveys the paper conveyed from the paper feeding unit, and the paper is fed to the registration roller adjustment unit. In a sheet conveying apparatus that starts conveying a sheet again at a predetermined timing after abutment and deflection, the leading end of one sheet member made of an elastic body is at a predetermined angle to the approximate center of the antinode of the other sheet member And a buffer means for deforming the sheet member as the paper is bent, and the invention according to claim 2 is the buffer means according to claim 1, wherein The sheet member is disposed so that the most swelled portion of the deflection of the sheet is in contact with the vicinity of the contact point at which the leading end of the sheet member contacts the approximate center of the antinode of the other sheet member. Invention In Items 1 and 2, as the sheet conveyance path to the registration roller adjusting means, the first conveyance path for conveying the sheet from the uppermost tray among the multiple stages of trays provided in the sheet feeding means, and other than the uppermost tray And a second transport path for transporting paper from the tray, and buffer means are provided in each of the first transport path and the second transport path.

  According to the first to third aspects of the present invention, the sheet conveyed from each tray of the sheet feeding unit passes through each conveyance path while being assisted by the conveyance auxiliary roller, and is conveyed to the registration roller adjusting unit. The sheet hits the registration roller adjusting means, and a deflection is formed. At this time, the most swollen portion of the bent portion of the paper hits the buffering means, and the two sheet members of the buffering means bulge outward. In this way, the sheet member is deformed as the sheet is deformed, so that the deflection force of the sheet is gradually dispersed, so that the sheet can be prevented from being bent without being bent instantaneously. The occurrence of collision noise can be reduced.

  According to a fourth aspect of the present invention, in the paper conveyance device according to any one of the first to third aspects, the registration roller adjustment unit includes a registration roller adjustment unit configured to convey a sheet conveyed from a detachable paper feed tray. In the paper transport device that starts the paper transport again at a predetermined timing after the paper is abutted and deflected, into the opening for carrying the paper in the opening of the attachment / detachment port from which the optional device has been removed. An exterior portion that functions as a protruding sound insulation means is provided.

  The invention according to claim 4 has the same effect as that of the invention according to claims 1 to 3, and is provided with an exterior portion of the sound insulation means at the attachment / detachment opening, so that it can be worn when the optional device is not used. It is possible to prevent the leakage of the sound that the paper strikes the registration roller adjusting means from the opening for carrying the paper at the opening of the exit and the sound that occurs when the paper is bent.

  According to a fifth aspect of the present invention, in the paper conveyance device according to any one of the first to fourth aspects, when the registration roller adjustment unit is operated at a predetermined timing and the conveyance of the paper is started again, the registration roller adjustment unit The paper conveyance speed is faster than the paper conveyance speed of the paper conveyance means one upstream.

  According to the fifth aspect of the present invention, the same effects as the first to fourth aspects of the invention can be obtained, and the registration roller adjusting means is driven in accordance with the timing of image formation to feed the paper to the image forming unit. In the re-conveying direction, only the registration roller adjustment unit is not driven, and the rotation speed of the registration roller adjustment unit is driven faster than the rotation speed of the downstream feed roller. Disappears as the paper is transported. Therefore, there is no occurrence of a sound in which the deflection is suddenly expanded by driving only the registration roller adjusting means as in the prior art.

  According to a sixth aspect of the present invention, in the paper conveyance device according to any one of the first to fifth aspects, when the registration roller adjustment unit is operated at a predetermined timing and the conveyance of the paper is started again, the registration roller adjustment unit The sheet feeding unit is driven in synchronism with the sheet feeding unit, and thereafter the driving of the sheet feeding unit is stopped in a state where the sheet trailing edge is sandwiched by the sheet feeding unit.

  According to the sixth aspect of the invention, the same effects as those of the first to fifth aspects of the invention can be achieved, and the leading edge of the sheet abuts against the registration roller adjusting means to form a deflection. Then, in accordance with the timing of image formation, the registration roller adjusting unit is driven to convey the paper toward the image forming unit. Then, the drive of the paper feeding unit is stopped with the trailing edge of the paper remaining in the paper feeding unit by a predetermined length. In this way, by continuously driving the sheet feeding unit while leaving the trailing edge of the sheet by a predetermined length, it is possible to prevent the sheet from being continuously fed.

  According to a seventh aspect of the present invention, in the paper conveying device according to the sixth aspect, a stop time for sandwiching the rear end portion of the paper is calculated according to the paper size, and driving of the paper feeding unit is stopped based on the stop time. It is characterized by.

  According to the seventh aspect of the invention, the same effect as that of the sixth aspect of the invention can be obtained, and the stop time for sandwiching the trailing edge of the sheet is calculated according to the sheet size, and the sheet feeding means is calculated based on the stop time. Stop driving. Therefore, it is possible to prevent the paper from being continuously fed regardless of the size of the paper.

  According to the first to third aspects of the present invention, the sheet conveyed from the sheet feeding unit hits the registration roller adjusting unit and forms a sheet deflection. However, the sheet member is deformed along with the sheet deflection, whereby the sheet deflection is caused. Since the force is gradually dispersed, the vibration of the paper can be suppressed without being instantaneously bent, and the generation of sound can be reduced.

  The invention according to claim 4 has the same effects as those of claims 1 to 3 and is provided with an exterior portion of the sound insulation means at the attachment / detachment opening, so that the paper at the opening of the attachment / detachment opening is used when the optional device is not used. It is possible to prevent the sound of the paper from striking the registration roller adjusting means from the opening for carrying and the leakage of the sound generated when the paper is bent.

  The invention according to claim 5 has the same effects as those of claims 1 to 4, and only the registration roller adjustment means is not driven at the time of re-transport, and the rotation speed of the registration roller adjustment means is higher. Since it is driven faster than the rotational speed of the downstream side paper feed roller, there is no sound that the deflection is suddenly extended by driving only the registration roller adjusting means as in the prior art.

  The invention according to claim 6 has the same effect as that of the invention according to claims 1 to 5, and the drive of the paper feeding means is stopped by leaving the rear end of the paper by a predetermined length, thereby continuously. Thus, the paper can be prevented from being sent.

  According to the seventh aspect of the invention, the same effect as that of the sixth aspect of the invention can be obtained, and it is possible to prevent the paper from being continuously fed regardless of the size of the paper.

  Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 6 is a sectional view showing the outline of a digital copying machine as an embodiment of the image forming apparatus 100. The image forming apparatus 100 includes a main body 1 and a paper supply bank unit 2 capable of two-stage paper supply. Since only the main body 1 has a two-stage paper feed tray, the function of the image forming apparatus 100 can be exhibited without the paper feed bank unit 2. A route indicated by a solid arrow in FIG. 6 is a paper conveyance route at the time of image formation when paper is fed from the first tray 10 of the main body 1. When paper is fed from the second tray 11, the third tray 12, and the fourth tray 13 of the main body 1, the paper conveyance route is indicated by a broken line. Join the same route as the tray 10. FIG. 1 is a cross-sectional view of the paper feeding / conveying system portion (from the second tray to the photosensitive member 6) of FIG. Three transport paths A, B, and C are shown in the center portion of FIG.

  A is a path from the first tray 10. A sheet separated by only one sheet by the sheet feeding roller 14 and the separation pad 25 is detected by the registration detection 27 and is abutted against the registration roller pair 16, and after adjusting the timing while forming a deflection, goes to the photoreceptor 6. .

  B is a route from the second tray 11. The sheet separated by the sheet feeding roller 22 and the separation pad 26 is directed upward while being assisted by the conveyance assisting roller 23, and is directed to the relay roller pair 24. The sheet passes further through the relay detection 28 located at the same position as the relay roller pair 24 and further joins the path A. Thereafter, the operation is the same as that of the sheet from the first tray 10.

  C is a paper path when a double-sided conveyance unit (not shown), a large-volume paper supply bank (not shown), etc., which are external options, are installed. The exterior 31 has an opening 30 for paper conveyance, and is provided as an external option. If the option is not installed, it is open as it is. The sheet conveyed from the external option immediately joins the path A and performs the same operation as the sheet from the first tray 10.

  In this embodiment, the sound leaked from the opening 30 when no external optional device is installed and the paper fed from the first tray 10 or the other trays 11, 12, 13 hit the registration roller pair 16. The impact sound that occurs when forming deflection is reduced. When an external option is installed, since the opening 30 is blocked by the option, no sound leakage is required, and thus this configuration is not necessary.

  A deflection forming portion 46 for reducing the collision of the paper fed from the first tray 10 with the registration roller pair 16 and a deflection forming portion 47 for the paper fed from other than the first tray 10 are provided. The deflection forming portion 47 is provided with resin or metal guide members 40 and 43 in the paper conveyance direction, and the guide members 40 and 43 are arranged by combining two Mylars 41, 42, 44 and 45 which are elastic films. . The other mylars 42 and 45 are provided at a predetermined angle in the approximate center of the belly of one mylar 41 and 44.

  2 is a diagram showing a change in the shape of the mylars 41 and 42 when paper is fed from the first tray 10, FIG. 3 is a diagram in which paper is actually conveyed from the first tray, and FIG. 4 is paper fed from the second tray 11. FIG. 5 shows a diagram in which a sheet is actually conveyed from the second tray 11. The paper fed from the first tray 10 passes between the paper feed roller 14 and the separation pad 25, and the leading edge of the paper hits the registration roller pair 16. Then, it stops for a predetermined time in order to make the timing of image formation. At this time, the paper forms a slack. It arrange | positions so that the most swelled part of a sag may be near the contact point of mylar 41 and 42. Thus, by bringing the two mylars 41 and 44 into contact with each other, it is possible to suppress the mutual vibration between the mylars 41 and 44. Deformation of the Mylars 41 and 44 causes the sheet to bend while the force is gradually dispersed. Therefore, the sheet does not bend flexibly and the vibration of the sheet is suppressed, so that the generation of noise is small. When the paper is fed from the second tray 11, the above-described operation is performed and the same effect is obtained. Moreover, since the sound which leaks to the opening part 30 is shielded by the exterior part 31a, it leads to noise reduction.

  Next, other embodiments will be described. In the description, parts having the same functions and effects as those described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the second embodiment, a method for preventing a sound generated when paper is re-fed and caused by a sudden extension of the deflection of the leading edge of the paper will be described. FIG. 7 is a block diagram of a control system that is a transport apparatus according to the present invention. The control means 84 includes a central processing unit (CPU) having various determination and processing functions, registration detection 27, relay detection 28, paper size detection 33, and the like. A ROM that is a program memory that stores a program and fixed data for controlling ON / OFF of the main motor 35, the registration clutch 36, the paper feed clutch 37, and the relay clutch 38 in response to the signal from the main motor 35, and processing data are stored. It has a RAM which is a data memory, an input / output circuit (I / O) and the like.

  FIG. 8 is a diagram for explaining the conveyance path length from the sheet feeding trays 10 and 11 to the registration roller pair 16 and the sheet conveyance speed. The following time is based on the assumption that there is no slip of the paper by the roller. When the distance from the first tray 10 to the registration roller pair 16 is L1 = 90 mm and the conveyance speed is 180 mm / s, the conveyance time is 0.5 seconds. When the distance from the second tray 11 to the relay roller pair 24 is L2 = 90 mm and the conveyance speed is 180 mm / s, the conveyance time is 0.5 seconds. When the distance L3 from the relay roller pair 24 to the registration roller pair 16 is 110 mm and the conveyance speed is 180 mm / s, the conveyance time is 0.61 seconds. After the registration roller pair 16, the conveyance path length from the first tray 10 to the registration roller pair 16 is L1 = 90 mm, and the conveyance path length from the second tray 11 to the registration roller pair 16 is L2 + L3 = 200 mm.

  In short, the first tray 10 has a short distance to the registration roller pair 16 and there is not much influence even if the conveyance speed is lowered. Therefore, after the conveyance speed is lowered and the sheet is bent, the registration roller pair 16 is re-conveyed when the sheet is conveyed again. And the paper feed roller 14 were operated simultaneously to carry the paper while keeping the deflection of the paper. Further, the paper feed clutch 37 is disconnected so that a 10 mm portion from the rear end of the paper remains on the paper feed roller 14.

  FIG. 9 is an explanatory diagram of paper feed tray size detection. Although all the trays 10, 11, 12, and 13 have the same configuration, the first tray 10 will be described here. A handle 34 for pulling out the tray 10 and a separation pad 25 are disposed on the tray 10. Also, dial-switchable paper size detectors 32 and 33 are attached to the front side of the first tray 10. With the first tray 10 pulled out, the dial 32 is rotated to select the set paper size. When the first tray 10 is set in the main body 1 in this state, the size detection switch 33 on the main body 1 side is pushed according to the paper size set in the dial. The size detection 33 detects the presence / absence of a tray set and the paper size.

  FIG. 10 is a timing chart for explaining the second embodiment. The paper conveyance speed is 120 mm / s from the paper feed to the registration roller pair 16, and 120 mm / s after the registration roller pair 16. In the figure, English letters a, b, c,... Are operations for the first sheet, and Roman numerals i, ii, iii,. A indicates deflection and B indicates timing adjustment. In the embodiments of the present invention, all A4 landscape paper is used.

  In response to the start signal, the main motor 35 is rotated (a), and after a predetermined time has elapsed, the sheet feeding clutch 37 is turned on (b), the sheet feeding roller 14 is rotated, and the first sheet is fed from the first sheet feeding tray 10. To start. When the leading edge of the paper reaches the registration sensor 27 (c), the paper feed clutch 37 is turned off after a predetermined time has elapsed, and the rotation of the paper feed roller 14 is stopped (d). Between cd, the leading edge of the sheet abuts against the stopped pair of registration rollers 16 to form a deflection. The timing adjustment time for image formation is taken between de, and then the registration clutch 36 and the paper feed clutch 37 are turned on (e, f), and the paper feed roller 14 and the resist roller pair 16 are rotated. The paper is transported while being bent. Then, with the rear end portion of the sheet approximately 10 mm remaining on the sheet feed roller 14, the sheet feed clutch 37 is turned off to stop the sheet feed roller 14 (g). Next, the feeding of the second sheet is started (i), and after the first sheet is removed from the registration roller pair 16 (h), the registration clutch 36 is turned off after a predetermined time has elapsed. Subsequent operations (ii to viii) of the second sheet are the same as those of the first sheet, and thus description thereof is omitted.

  As described above, the first tray 10 temporarily stops with the leading edge of the sheet abutting against the registration roller pair 16, and drives the registration roller pair 16 in time with the image forming unit to feed the sheet to the transfer position. However, since the registration roller pair 16 and the paper feed roller pair 14 are simultaneously driven at the same rotational speed, the paper can be moved while maintaining its deflection, and only the registration roller pair 16 is driven as in the prior art. There is no paper collision noise caused by the sudden cramping. Further, since the conveying speed is slowed, the impact sound when colliding with the registration roller pair 16 can be reduced.

  Further, since the paper size can be detected by the size detections 32 and 33 of the first tray 10, the portion where the trailing edge of the paper is left on the paper feed roller 14 by inputting the stop timing data of the paper feed clutch 37 in advance. (10 mm) can be set according to the paper size. In addition, when waiting for the second sheet to be fed until the trailing edge of the first sheet passes through the registration sensor, the sheet feeding timing is delayed by 0.32 seconds for each sheet. The number of images formed becomes smaller. Therefore, when the second and subsequent sheets are fed, the sheet interval is set in advance so that the sheet is fed at the set timing. For example, if the setting is made so that the second sheet is fed 0.25 seconds before the first sheet passes the registration sensor 27, the first sheet is 0.25 seconds later than the conventional one, but two sheets From the first eye on, the image can be formed at the same timing as in the prior art.

  Even when the paper feed roller 14 and the registration roller pair 16 are set at a constant velocity, the registration roller pair 16 has a slip rate of 1 to 2% because the axial load applied to the roller shaft is about 4 to 6 kgf. The sheet feed roller 14 is about 300 gf and the slip rate is 10%, the relay roller pair 24 is about 500 gf to 1 kgf and the slip rate is 2 to 8%, and the deflection is absorbed by the amount of slip, and the generation of noise is reduced. In addition, the axial load of the registration roller pair 16 is large, followed by the relay roller pair 24, and the smallest one is the paper feed roller 14. The drive on the downstream side is stopped when the drive on the upstream side is cut off. This is because the paper is easily pulled by force.

  FIG. 11 is a timing chart showing a state where one sheet is passed from the second tray 11. In response to the start signal, the main motor 35 is rotated (a), and after a predetermined time has elapsed, the sheet feeding clutch 37 is turned ON (b), the sheet feeding roller 22 is rotated, and the first sheet feeding from the second tray 11 is started. To do. After the operation of the paper feed clutch 37, the relay clutch 38 is turned on after a predetermined time has elapsed (c), and the relay roller pair 24 is rotated to transport the paper. When the sheet reaches the relay sensor 28 (d), the sheet feeding clutch 37 is turned off after a certain period of time, and the rotation of the sheet feeding roller 22 is stopped (e). In this state, since the sheet is still sandwiched between the sheet feeding roller 22 and the separation pad 26, the sheet is pulled by the relay roller pair 24 until the trailing end of the sheet comes off. The leading edge of the paper reaches the registration sensor 27 (f), and after a predetermined time has elapsed, the relay clutch 38 is turned off, and the rotation of the relay roller pair 24 stops (g). The leading edge of the sheet abuts against the resist roller pair 16 that is stopped between f and g to form a deflection. After the timing adjustment time for image formation (between gh), the registration clutch 36 and the relay clutch 38 are turned on again, the driving of the registration roller pair 16 and the relay roller 24 is resumed, and the sheet is kept bent. It is transported as it is.

  As described above, also in the second tray 11, after the sheet is bent, the registration roller pair 16 and the relay roller pair 24 are simultaneously driven at the time of re-conveying, so that the sheet can be conveyed while maintaining the deflection, and the paper is rapidly It can prevent the sound when it is stretched. Further, unlike the first paper feed unit, the rear end of the paper is held by the relay roller pair 24 instead of the paper feed roller 22, so that the double feed like the paper feed roller 14 of the first tray 10 is performed. Therefore, it is not necessary to cut off the driving of the relay roller pair 24.

  Since the sheet cannot be conveyed at high speed in the second tray 11 of the second embodiment described above, the image forming processing capability is reduced as compared with the conventional case. As a reference example of this embodiment, the conveyance speed to the registration roller pair 16 can be performed at a high speed. In the second tray 11, a second drive transmission means for directly connecting the registration roller pair 16 and the relay roller pair 24 is provided, and the second drive is performed while the sheet is conveyed to the registration roller pair 16. The transmission means is not driven, and the registration roller pair 16 and the relay roller pair 24 are driven simultaneously by the second drive transmission means when re-conveying from the registration roller pair 16. The state where the second drive transmission means is provided will be described below.

  12 is a schematic plan view of the paper conveyance drive system, and FIG. 13 is a side sectional view of FIG. The main motor 35 is transmitted to the paper conveyance drive system via the first timing belt 51. The first timing belt 51 rotates the first gear pulley 52 disposed on the stud 66. The first gear pulley 52 meshes with the resist gear 53 and the idle gear 54. The registration gear 53 is integral with the registration clutch 36 and transmits the driving of the registration gear 53 to the registration roller pair 16 via the registration shaft 65. The idle gear 54 meshes with the second gear pulley 55, and the second gear pulley 55 meshes with the first paper feed gear 56 and the relay gear 58.

  The first paper feed gear 56 includes a paper feed shaft 68, a bearing 76, and a paper feed clutch (not shown). The relay gear 58 includes a relay clutch 38 and drives the relay roller pair 24 via the relay roller shaft 70. The second gear pulley transmits drive to the third gear pulley 61 via a second timing belt 57 having an idle pulley 60 and a belt tighter 59. The third gear pulley 61 rotates around the stud 72 and serves as a drive source for the second paper feed unit. The third gear pulley 61 meshes with the second paper feed gear 62 and the second relay clutch 63.

  In this reference example, the second drive transmission means is provided separately from the paper conveyance drive system 49 described above. That is, a first pulley 80 is provided between the registration roller pair 16 of the registration roller shaft 65 and the bearing 75, and a second pulley 81 is provided on the relay roller shaft 70. The shaft 65 and the relay roller shaft 70 can be directly transmitted. A one-way clutch 82 is provided on either one of the pulleys 80 and 81.

  FIG. 14 shows an example in which the one-way clutch 82 is provided on the second pulley 81 of the relay roller shaft 70, and FIG. 15 shows an example in which the one-way clutch 82 is provided on the first pulley 80 of the registration roller shaft 65. FIG. 14 shows a case where the first pulley 80 rotating integrally with the registration roller shaft 65 and the second pulley 81 incorporating the one-way clutch 82 are driven counterclockwise by the timing belt 48. That is, when the second pulley 81 tries to rotate counterclockwise with respect to the relay roller shaft 70, the wedge action between the cam surface of the one-way clutch 82 and the relay roller shaft 70 due to the effect of the roller 90 and the chevron shape 91. The relay roller shaft 70 is driven. This is a case where the registration roller pair 16 is rotated and the driving of the relay roller pair 24 is cut off.

  Further, when the second pulley 81 tries to rotate clockwise relative to the relay roller 70 (actually, the relay roller shaft 70 tries to rotate counterclockwise with respect to the second pulley 81), Due to the effects of the roller 90 and the chevron shape 91, the relay roller shaft 70 rotates idly.

  Next, when the registration roller pair 16 is transporting the first sheet to the photosensitive member at 120 mm / s, the second sheet is transported by the relay roller pair 24 toward the registration roller pair 16 at 180 mm / s. The case where it will be described. In this case, the relay roller shaft 70 rotates at a rotation speed corresponding to a conveyance speed of 180 mm / s, and the second pulley 81 rotates at a rotation speed corresponding to a conveyance speed of 120 mm / s. In both cases, the rotational speed of the second pulley 81 is 0, and the rotational speed of the relay roller shaft 70 is 60 mm / s. When the relay roller shaft 70 rotates at a relatively high speed, the shaft rotates idly by the action of the one-way clutch 82, and the drive of the relay roller shaft 70 is not transmitted to the registration roller shaft 65.

  In FIG. 15, the mounting direction of the one-way clutch 82 is set such that the angle shape with respect to the rotational direction of the shaft is opposite to that in FIG. In this case, when the registration roller shaft 65 attempts to rotate counterclockwise with respect to the second pulley 81, the wedge action between the cam surface of the one-way clutch 82 and the registration roller shaft 65 is caused by the effect of the roller 90 and the chevron shape. The two pulleys 81 rotate. Therefore, when the registration roller pair 16 starts refeeding, even if the driving of the relay roller pair 24 is cut off, the relay roller pair 24 rotates in synchronization with the rotation of the registration roller pair 16.

  When the relay roller shaft 70 rotates counterclockwise and the drive is transmitted to the second pulley 81 by the first pulley 80 and the timing belt 48, that is, when the registration roller pair 16 is in the standby state, the one-way clutch 82 is used. As a result, the second pulley 81 idles and does not transmit drive to the registration roller shaft 65. Further, when both the registration roller shaft 65 and the second pulley 81 are driven in the same direction, and the second pulley 81 rotates at a relatively high speed as in FIG. Pull the pulley idle. Accordingly, the driving of the relay roller shaft 70 is not transmitted to the registration roller shaft 65. However, the timing belt 48 operates.

  That is, in the reference example of FIG. 14, the timing belt 48 operates only when the registration roller pair 16 is driven, but in the reference example of FIG. 15, when either the registration roller pair 16 or the relay roller pair 24 is driven, The timing belt 48 operates. Therefore, the generation of noise is less because the operation of the timing belt 48 which is unnecessary in FIG. 14 is not performed.

  The flow of paper when it is fed from the second tray 11 will be described with reference to the timing chart of FIG. 16, and the case where two sheets of A4 landscape size paper are passed continuously will be explained. In order to increase the image forming capability, when the first sheet passes through the relay sensor 28, the second sheet is fed. The sheet conveyance speed is 180 mm / s from the paper feed roller 22 to the registration roller pair 16, and the image forming speed is 120 mm / s after the registration roller pair 16.

  In response to the start signal, the main motor 35 is rotated (a), and after a predetermined time has elapsed, the sheet feeding clutch 37 is turned ON (b), the sheet feeding roller 22 is rotated, and the first sheet feeding from the second tray 11 is started. To do. After the operation of the paper feed clutch 37, the relay clutch 38 is turned on after a predetermined time has elapsed (c), and the relay roller pair 24 is rotated to transport the paper. When the sheet reaches the relay sensor 28 (d), the sheet feeding clutch 37 is turned off after a certain period of time, and the rotation of the sheet feeding roller 22 is stopped (e).

  The leading edge of the paper reaches the registration sensor 27 (f), and after a predetermined time has elapsed, the relay clutch 38 is turned off, and the rotation of the relay roller pair 24 stops (g). The leading edge of the sheet abuts against the resist roller pair 16 that is stopped between f and g to form a deflection. After the timing adjustment time for image formation (between gh), the registration clutch 36 is turned on (h), the registration roller pair 16 is driven, and the sheet is conveyed to the image forming unit. Conventionally, when the relay clutch 38 is OFF, the relay roller pair 24 does not rotate. However, since the one-way clutch 82 is connected in this reference example, the drive is transmitted to the relay roller shaft 70 at the same timing as the registration roller shaft 65. The relay roller pair 24 rotates. Therefore, since the sheet is conveyed in a state in which the deflection of the sheet is maintained, no sound is generated that causes the sheet to expand rapidly (hatched portion indicated by X).

  When the paper feed clutch 37 is turned on again (i) and the paper feed roller 22 rotates, the second sheet is fed from the second tray 11. Then, after a predetermined time has elapsed, the relay clutch 38 is turned on. (Ii) The relay roller pair 24 is rotated and the sheet is conveyed. When the second sheet reaches the relay sensor 28 (iii), the sheet feeding clutch 37 is turned off after a certain period of time, and the rotation of the sheet feeding roller 22 is stopped (iv). At this time, the first sheet passes through the registration sensor 27 (j), and the registration clutch 36 is turned off after a certain period of time (k). When the second sheet reaches the registration sensor 27 (v), the relay clutch 38 is turned off after a certain period of time (vi), and the rotation of the relay roller pair 24 is stopped. Between (vi) and (vii), both the relay clutch 38 and the registration clutch 36 are OFF, and the timing is reached by stopping the sheet. Thereafter, the registration clutch 36 is turned on (vii), and the registration roller pair 16 is driven to convey the sheet to the image forming unit. Between (vii) and (viii), the relay clutch 38 is OFF, but the one-way clutch 82 is connected. 24 rotates. Accordingly, the sheet can be transported in a state in which the deflection is maintained, and generation of a sound that the sheet is rapidly expanded can be prevented (shaded portion indicated by Y).

  The operations of the relay clutch 38, the registration clutch 36, and the one-way clutch 82 are shown below the timing chart of FIG. The relay clutch 38 and the registration clutch 36 are OFF between a and c, and only the relay clutch 38 is ON between c and g, and the relay roller shaft 70 is rotated to convey the sheet at high speed. At this time, the one-way clutch 82 idles and the drive is not transmitted to the pulley. Between g and h, both the relay clutch 38 and the registration clutch 36 are OFF, and the timing is being adjusted by stopping the sheet. Between h and II, both the relay clutch 38 and the registration clutch 36 are OFF, but since the one-way clutch 82 is connected, the drive is transmitted to the relay roller shaft 70 at the same timing as the registration roller shaft 65, and the relay roller pair 24. Rotates.

  Therefore, since the sheet is conveyed while keeping the deflection of the sheet, the sound of sudden expansion of the sheet is not generated. Between ii and k, the relay clutch 38 is turned on to pass the second sheet of paper. At this time, the registration clutch 36 is also ON because the first sheet is being conveyed. That is, the second sheet is conveyed at 180 mm / s by the relay roller pair 24, and the first sheet is conveyed by 120 mm / s by the registration roller pair 16. At this time, the relay roller shaft 70 is rotated by the relay roller pair 24 at a rotation speed of 180 mm / s, and the pulley is rotated by the timing belt 48 at a rotation speed of 120 mm / s. When the rotation speed of the relay roller shaft 70 is higher than that of the pulley, the one-way clutch 82 rotates idly, so that the registration roller pair 16 does not rotate at 180 mm / s.

  Between k and vi, the relay clutch 38 passes the second sheet of paper and hits the registration roller pair, so that it is in the ON state. On the other hand, the registration clutch 36 is in an OFF state because the first sheet has been sent out. At this time, the one-way clutch 82 idles, so that the drive is not transmitted to the pulley. Between vi and vii, both the relay clutch 38 and the registration clutch 36 are in the OFF state, and the timing is being adjusted by stopping the sheet.

  Between vii and viii, the relay clutch 38 is OFF and the registration clutch 36 is ON. Although the relay clutch 38 is OFF, since the one-way clutch 82 is connected, the drive is transmitted to the relay roller shaft 70 at the same timing as the registration roller shaft 65, and the relay roller pair 24 rotates. Accordingly, since the sheet is conveyed while keeping the deflection of the sheet, there is no sound that the sheet expands rapidly.

  Thus, by adding a drive system using the one-way clutch 82 between the registration roller shaft 65 and the relay roller shaft 70, the relay roller pair 24 is rotated at a high speed until the sheet is conveyed to the registration roller pair 16. In this case, the rotation of the relay roller shaft 70 is not transmitted to the registration roller shaft 65. Further, when the paper is re-conveyed from the registration roller pair 16, the relay roller shaft 70 and the registration roller shaft can be simultaneously rotated by the second driving system, and the deflection of the paper is maintained from the registration roller pair 16. It can be transported, and the sound generated when the paper is abruptly stretched can be prevented.

  FIG. 17 is a diagram showing an experimental effect of the sheet feeding device of the present invention. In the conventional example and the present embodiment, the noise measurement starts at the same timing as the paper feed start, and the measurement distance, the installation location of the measurement instrument, and the like are the same. The peak of the graph at the start of paper feed is the impact sound of the clutch when the paper feed clutch 37 is turned on. The collision sound when the sheet collides with the registration roller pair 16 is lower by about 10 dB in this embodiment than in the conventional example, and a significant difference is generated. This is because, in this embodiment, the sheet is bent slowly by the impact being absorbed by the mylar, and the sound generated by the exterior portion 31a is shielded. The peak after the timing adjustment is an impact sound when the registration clutch 36 is turned on.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, although the present embodiment has been described assuming a monochrome copying machine, it may be a color copying machine, a printer, a facsimile, or the like. The embodiment described using the second tray as an example can also be applied to a case where the second tray is conveyed.

  In the sheet conveying apparatus according to the present invention, the deflection of the sheet conveyed from the sheet feeding unit abuts against the registration roller adjusting unit is gradually dispersed by the deformation of the sheet member along with the deflection, and the moment is distributed. In addition, when the sheet is re-conveyed from the registration roller adjustment unit, the registration roller adjustment unit is driven faster than the downstream feed roller, and only the registration roller adjustment unit is driven to cause the deflection. It is useful for application to electrophotographic copying machines, printers, facsimiles, and the like that carry paper and can suppress the vibration of paper and reduce the generation of sound without abrupt expansion.

Schematic diagram of the paper transport device of this embodiment The figure which shows the shape change of mylar when feeding from the 1st tray Diagram of actual paper transport from the first tray The figure which shows the shape change of the mylar at the time of feeding from a 2nd tray Diagram of actual paper transport from the second tray Sectional view showing the outline of a digital copying machine as an embodiment of an image forming apparatus The block diagram of the control system which is a conveyance apparatus of this invention Diagram of actual paper transport from the first tray Illustration of paper tray size detection Timing chart for explaining the second embodiment In the second embodiment, a timing chart showing a state in which one sheet is passed from the second tray Schematic plan view of the paper transport drive system Side sectional view of FIG. Diagram of a one-way clutch provided on the second pulley of the relay roller shaft Diagram of a one-way clutch provided on the first pulley of the registration roller shaft In the reference example, a timing chart showing the flow of paper when fed from the second tray The figure which shows the experimental effect of the paper feeder of this invention A diagram showing a conventional paper transport device Timing chart showing a case where paper is conveyed from the first tray of the conventional example Timing chart showing the case of transporting paper from the second tray of the conventional example

Explanation of symbols

14, 22 Paper feed roller (paper feed means)
16 Registration roller pair (registration roller adjustment means)
24 Relay roller pair (relay conveyance means)
40, 43 Guide member (buffer means)
41, 42, 44, 45 Mylar (sheet member)
82 One-way clutch (one-way drive means)

Claims (7)

A sheet feeding unit that accommodates the sheet and conveys the sheet; and a registration roller adjustment unit that conveys the sheet conveyed from the sheet feeding unit. The sheet is abutted against the registration roller adjustment unit to have a deflection. Then, in the paper transport device that starts transporting the paper again at a predetermined timing,
A cushioning means in which the tip of one sheet member made of an elastic body is slidably in contact with the center of the antinode of the other sheet member at a predetermined angle so that the sheet member is deformed as the sheet is bent A sheet conveying apparatus comprising:   In the buffering means, the sheet member is arranged so that the most swelled portion of the deflection applied to the paper is in contact with the vicinity of the contact point where the tip of one sheet member contacts the approximate center of the antinode of the other sheet member. The sheet conveying apparatus according to claim 1.   As a paper transport path to the registration roller adjusting means, a first transport path for transporting paper from the uppermost tray among a plurality of trays in the paper feeding means, and a tray other than the uppermost tray. 3. The sheet conveying apparatus according to claim 1, further comprising a second conveying path that conveys the sheet, wherein the buffer unit is provided in each of the first conveying path and the second conveying path. And a registration roller adjustment unit that conveys the sheet conveyed from the detachable paper feed tray. After the sheet is abutted against the registration roller adjustment unit to bend, the conveyance of the sheet is started again at a predetermined timing. In the paper transport device to
The exterior part which functions as a sound insulation means which protruded in the apparatus was provided in the opening part which conveys the sheet | seat which has the opening of the attachment / detachment port which removed the option apparatus, The any one of Claims 1-3 characterized by the above-mentioned. The paper conveying apparatus as described.   When the registration roller adjusting unit is operated at the predetermined timing and the conveyance of the paper is started again, the paper conveyance speed of the registration roller adjustment unit is faster than the paper conveyance speed of the upstream paper conveyance unit. The paper conveying apparatus according to claim 1.   When the registration roller adjustment unit is operated at the predetermined timing and the conveyance of the sheet is started again, the registration roller adjustment unit and the sheet feeding unit are driven in synchronization, and then the sheet trailing edge is driven by the sheet feeding unit. 6. The sheet conveying apparatus according to claim 1, wherein the driving of the sheet feeding unit is stopped in a state where the section is sandwiched.   7. The paper conveying apparatus according to claim 6, wherein a stop time for sandwiching the rear end portion of the paper is calculated according to the paper size, and driving of the paper feeding unit is stopped based on the stop time.

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