JP2005280974A - Paper sheet carrier, paper feeder and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the noise when a paper sheet advances into a nip of a pair of resist rollers to control the paper feed timing of an image forming apparatus. <P>SOLUTION: A paper sheet S to be fed to a transfer drum of an image forming apparatus generates large noise because the advancing force by a loop before resist rollers is used when the paper sheet advances into a nip N of a pair of resist roller pairs 3 to adjust the paper feed timing. Thus, a pair of carrying rollers 4 before the pair of resist rollers 3 are inclined by the angle θ (0.8-3.0°) with respect to the carrying direction of the paper sheet S and the paper sheet S is meandered. A leading tip SL of the paper sheet S is gradually abutted on a nip part of the resist rollers 3 and simultaneously performs the meandering correction and the paper feed timing control, and no large noise occurs. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is applied to, for example, an image forming apparatus such as a printer, a facsimile machine, and a copying machine adopting a transfer type or direct type image forming process such as an electrophotographic method and a liquid discharge method, office equipment, and other various paper material using devices. , Paper materials (transfer sheets, photosensitive paper, thermal paper, electrostatic paper, printing paper, originals, cards, envelopes, postcards, etc.) The present invention relates to a sheet conveying apparatus, a sheet feeding apparatus, and an image forming apparatus for conveying from a sheet feeding apparatus such as a sheet feeding cassette to a process means such as an image forming unit.

  In general, in a paper conveyance device of an image forming apparatus that performs recording such as a copying machine, a laser beam printer, a printing machine, etc., a flex loop is applied to the paper material in order to control the paper material feeding timing to the process means for forming an image. And the leading edge of the paper material is made to enter the nip of the pair of registration rollers by a loop advance input.

  FIG. 9 shows a sheet conveying apparatus according to a conventional example. The conveying roller pair 104 is rotated by a driving unit (not shown) so that the sheet S is indicated by an arrow on the left side from a sheet feeding unit or the like located on the right side in the figure. Transport to.

  When the leading edge of the sheet S reaches the nip N of the registration roller pair 103, the registration roller pair 103 is held in the rotation stopped state, and the leading edge of the sheet S is the nip of the registration roller pair 103 in the rotation stopped state. The conveying roller pair 104 continues to convey the paper for a predetermined time and then stops. Thereafter, the registration roller pair 103 rotates and conveys the paper S to the next process section having a process means such as transfer. As a result, it is possible to align the image forming process and the paper feed timing, and it is possible to prevent the positional deviation of the recorded image.

  In addition, a deflection loop (pre-registration loop) is formed on the sheet S before the registration roller pair, and the leading edge of the sheet S is made parallel to the nip line of the registration roller pair 103 by the deflection reaction force. Skew correction is performed.

  This type of apparatus is disclosed in Patent Document 1 and Patent Document 2, for example.

As described above, in the conventional image forming apparatus, in order to accurately adjust the recording position, the sheet is brought into contact with the nip of the registration roller pair, the leading edge of the sheet is aligned, the position timing with respect to the image forming unit is aligned, Paper skew was corrected.
JP-A-6-191686 Japanese Patent Publication No. 4-18303

  However, in the conventional configuration in which the conveyed paper is brought into contact with the nip portion of the registration roller to form a deflection loop to correct the skew of the paper, the purpose is to correct an accidental skew. The design is such that the sheet is conveyed at right angles to the nip of the registration roller pair. Accordingly, the majority of sheets actually conveyed to the registration rollers have traveled substantially at right angles to the nip of the registration roller pair, and the leading edge of the sheet has been in momentary contact with the nip line almost in parallel.

  However, when the sheet conveying device conveys the sheet at right angles to the nip of the registration roller pair in this way and the leading edge of each sheet momentarily contacts the registration roller, a large noise is generated at the time of contact, and the continuous In addition, when printing on a large number of sheets, since instantaneous contact with the nip portion of the registration roller occurs every time, the noise during printing is increased, causing discomfort to the user.

  Further, the conveyance rollers other than the registration rollers are configured to convey the sheet so as to abut against the nip of the conveyance roller pair perpendicularly. Since the conveyance roller rotates when the paper abuts, the noise level is lower than that of the registration roller, but noise is generated when the conveyance roller abuts on the nip portion as described above.

  The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and reduces the noise generated when the paper material fed and conveyed from the paper feeding device comes into contact with the registration roller and the conveyance roller. It is an object of the present invention to provide a sheet conveying device, a sheet feeding device, and an image forming apparatus that can perform feeding and conveying with low operation noise.

  In order to achieve the above object, a paper transport apparatus according to the present invention transports a paper material from a paper feed unit to the process unit via the registration roller pair and a registration roller pair for controlling a paper feed timing for the process unit. And a skew feeding means for inclining the sheet material by a predetermined angle with respect to the conveyance direction of the conveyance mechanism and causing the leading edge of the sheet material to enter obliquely with respect to the nip of the pair of registration rollers. It is characterized by having.

  A sheet feeding device according to the present invention includes a sheet feeding unit that supplies a sheet material to a process unit by a conveying mechanism including a pair of conveying rollers, and the sheet material is inclined by a predetermined angle with respect to a conveying direction of the pair of conveying rollers. And an oblique feeding means for feeding from the paper feeding means to the transport mechanism.

  The image forming apparatus according to the present invention includes an image forming unit for forming an image, a registration roller pair for controlling a sheet feeding timing for the image forming unit, and the image forming unit from a sheet feeding unit through the registration roller pair. A transport mechanism that transports the paper material to the section, and the paper material is inclined at a predetermined angle with respect to the transport direction of the transport mechanism, and the leading edge of the paper material enters obliquely with respect to the nip of the registration roller pair And a skew feeding means.

  In a sheet conveying apparatus having a pair of registration rollers for nipping and conveying a sheet material, and feeding the sheet material fed and conveyed from a paper feeding cassette or the like of an image forming apparatus to a process means for image formation or the like in a timing manner In order to allow the sheet material to enter the nip of the registration roller pair in a skewed state, for example, the conveying roller is disposed at a predetermined angle θ with respect to the registration roller.

  Alternatively, the sheet material is obliquely fed from a sheet feeding unit such as a manual sheet feeding unit that supplies the sheet material or a sheet feeding cassette in the apparatus.

  With such a configuration, the leading edge of the paper material is made to enter obliquely with respect to the nip of the conveying roller or the registration roller, and the paper material is prevented from instantaneously contacting the nip portion. That is, by causing the sheet material to incline with respect to the nip of the registration roller pair and gradually contact the sheet material, noise generated when the registration roller contacts the nip portion can be greatly reduced.

  The skew amount of the paper material is set to an inclination angle of 0.8 to 3.0 degrees with respect to the conveyance direction of the paper material, so that the skew correction function by the registration roller pair is not impaired and the contact with the registration roller is not impaired. Noise during contact can be effectively reduced.

  As shown in FIG. 1, the image forming apparatus is roughly divided into an image input unit A and an image output unit B. The image input unit A is, for example, an image information photoelectric reading mechanism, and stores image information for recording. After inputting and performing various processes, the image signal is sent to the image output unit B. An optical apparatus that projects and exposes a document image on the image carrier of the image output unit B may be used.

  The image output unit B is a transfer-type image recording mechanism using, for example, the transfer drum 1. The fixing unit 2 is on the downstream side of the transfer drum 1, the registration roller pair 3, the transport roller pair 4 is on the upstream side, and is under the guide. A sheet transport device including a plate 5 and a guide upper plate 6 is provided.

  Further, a toner image is formed on an image carrier such as a photoconductor, a dielectric, or a magnetic material by an appropriate image forming process such as an electrophotographic process, an electrostatic recording process, or a magnetic recording process according to input image information to the image output unit B. An image forming unit 7 which is a process unit for forming a transferable recording image such as a control unit 8, a control unit 8 which controls all operations of the apparatus, a manual sheet feeding unit 9 which is a sheet feeding unit, and a sheet feeding in the apparatus It has sheet feeding cassettes 10 and 11 as means.

  The sheet S, which is a sheet-like sheet material fed from either the sheet feeding unit 9 or the sheet feeding cassettes 10 and 11 through the sheet feeding roller 12, is registered with the registration roller pair 3 by a conveyance mechanism including a plurality of conveyance roller pairs. A predetermined deflection loop is formed between the upper guide plate 6 and the lower guide plate 5 between the pair of transport rollers 4 during the transport to the guide roller. The sheet fed from the registration roller pair 3 is conveyed to the transfer unit 7a of the image forming unit 7 by the transfer drum 1, and the sheet that has received the image transfer by the transfer unit 7a is sent to the fixing unit 2 for fixing the image.

  The first and second paper feeding cassettes 10 and 11 are automatic single sheet feeding mechanisms built in the upper and lower two stages in the image output unit B, and the paper S stacked and stored in the paper feeding cassettes 10 and 11. Are separated one by one from the uppermost one by the cooperation of the sheet feeding roller 12 and the separating member based on the sheet feeding start signal, and are fed upward by a plurality of conveying roller pairs or the like. In the manual sheet feeder 9, when the sheet S is inserted into the apparatus from the manual sheet feed table, the sheet is pulled into the apparatus by a sheet feeding roller (not shown).

  When the operation of the apparatus is started, the sheet S is fed from the sheet feeding unit 9 or the sheet feeding cassettes 10 and 11 and is conveyed to the registration roller pair 3 by the conveying roller pair 4.

  When the leading edge of the sheet S reaches the nip of the registration roller pair 3, the registration roller pair 3 is held in the rotation stopped state, and the leading edge of the sheet S hits the nip of the registration roller pair 3 in the rotation stopped state. After that, the conveying roller pair 4 continues to convey the sheet for a predetermined time and then stops.

  As a result, a predetermined deflection loop (pre-registration loop) is formed on the leading edge side of the sheet S along the guide upper plate 6, and the leading edge of the sheet is made parallel to the nip line of the registration roller pair 3 by the deflection reaction force. Then, the skew correction of the sheet S and the synchronization of the image formation and the sheet conveyance, that is, the sheet feeding timing is controlled.

  In the sheet conveying apparatus, as shown in FIG. 2, the conveying roller 4 is moved relative to the registration roller 3 as a skew feeding means for skewing the sheet S by a predetermined angle θ with respect to the nip N of the registration roller pair 3. Inclined by the predetermined angle θ.

  Alternatively, as shown in FIG. 5, the paper feeding cassettes 10 and 11 are provided with an oblique feeding means by two feeding rollers 22a and 22b having different rotational speeds, or the paper is manually fed as shown in FIG. The sheet feeding section 49 is configured to have a skew feeding means using horizontal resist plates 49a and 49b that feed the sheet while skewing it.

  With this configuration, the leading edge of the paper can be prevented from momentarily contacting the nip of the transport roller pair or registration roller pair, and the noise generated when the nip contacts can be greatly reduced. It becomes.

  Further, the skew amount of the paper is set to an angle θ = 0.8 to 3.0 degrees with respect to the transport direction, so that the noise at the time of contact with the registration roller is reduced without impairing the skew correction function of the registration roller pair. It can be effectively reduced.

  In the registration roller pair 3 shown in FIG. 2, the upper roller is a rubber material having a diameter of 15 mm, and the lower roller is a polyacetal resin having a diameter of 15 mm. The conveying roller pair 4 is made of a rubber material on both the upper and lower sides, and the distance d between the registration roller pair 3 and the conveying roller pair 4 is 200 mm.

  As shown in FIG. 2B, the conveying roller pair 4 is disposed to be inclined with respect to the registration roller pair 3 by an angle θ. As a result, the sheet S enters the nip N of the registration roller pair 3 with the leading edge SL skewed.

  That is, the sheet S conveyed by the conveying roller pair 4 first has the corner of the leading edge SL (the right corner in the figure) abuts the nip N of the registration roller pair 3, and then gradually the entire leading edge SL of the sheet S It contacts the nip N.

  In this way, the noise generated when the leading edge of the paper abuts the nip by first abutting the corner of the leading edge of the paper with the nip and avoiding that the entire leading edge of the paper abuts the nip instantaneously. Can be reduced.

  With respect to the skew amount of the sheet with respect to the nip of the registration roller pair, in this embodiment, the inclination angle of the conveyance roller pair is 1.0 degree.

  Further, the rotation of the registration roller pair is configured such that after the leading edge of the sheet comes into contact with the registration roller pair, the conveyance roller pair stops until the center of the sheet is pushed out to the registration roller side by 6 mm.

  The graphs of FIGS. 3 and 4 show the results of measuring the noise generated when the paper transport device of this embodiment is driven and the paper is fed.

  FIG. 3A shows a time-varying waveform of noise generated when the leading edge of the paper is conveyed perpendicularly to the nip of the registration roller as a comparative example, and FIG. 3B shows the paper in this embodiment. 2 shows a time-varying waveform of noise generated when the leading edge of the lens is made to enter obliquely with respect to the nip of the registration roller. The paper used was plain paper used for normal copying.

  4 (a) and 4 (b) are graphs showing the frequency characteristics of the time-varying waveforms in FIGS. 3 (a) and 3 (b).

  3 and 4 that the noise level when the paper comes into contact with the nip can be greatly reduced by bringing the front edge of the paper into contact with the nip of the registration roller in an inclined state. In particular, the noise around 500 Hz can be greatly reduced, and the noise can be reduced by about 7 dB even with the overall value.

  One contact is a short time of about several ms, but when the paper is continuously conveyed without using the skew feeding means, the noise as shown in FIG. The share of noise during printing is quite large. Therefore, reducing the noise level at the time of nip contact using the skew feeding means can be expected to have a great effect on reducing the user's discomfort.

  With the above-described skew amount in this embodiment, the skew caused by the pair of conveying rollers can be sufficiently corrected by the deflection loop of the sheet generated after contacting the nip of the registration roller pair and its reaction force. Thus, the image formation on the transfer drum was not affected.

  Note that when the skew angle θ is set to 0.8 degrees or less, there is almost no effect of noise reduction as in the present embodiment, and when it is set to 3.0 degrees or more, the above-mentioned registration is not performed. The skew amount could not be corrected by the previous loop, and the image recording position shifted.

  The material and shape of the registration roller, the separation distance between the conveyance roller and the registration roller, and the like can be arbitrarily set according to the situation. For example, the same effect can be obtained even when an OHP film is used as paper.

  In addition to the contact portion with the nip of the registration roller pair, for example, in the case of the transport roller, the roller rotates, but the noise is low, but the structure also contacts the transport roller in a skewed state. By doing so, the noise reduction effect at the time of contact could be obtained.

  In place of the paper feed roller 12 in FIG. 1 provided in the paper feed cassettes 10 and 11 as the paper feed device, as shown in FIG. By changing the rotational speeds of the paper feed roller 22a and the paper feed roller 22b, the paper S can be conveyed while being skewed at a predetermined angle with respect to the registration roller pair 3.

  Since the sheet can be skewed and brought into contact with the nip of the pair of registration rollers, the same effect as in the first embodiment can be obtained, and further, the sheet can be conveyed in a skewed state immediately after being pulled out from the sheet feeding cassette. Therefore, it is possible to reduce noise generated when the conveying roller pair and the like contact the registration rollers.

  As shown in FIG. 6A, two conveyance roller pairs 34a and 34b separated in the width direction of the paper S are provided, and can be driven separately.

  The angle at which the sheet S enters the nip N of the registration roller pair 3 is changed by driving the conveyance roller pair 34 a and the conveyance roller pair 34 b at different rotational speeds (conveyance speeds).

  For example, when the conveyance roller pair 34a is driven faster than the conveyance roller pair 34b, the left end of the leading edge SL of the paper S comes into contact with the nip N of the registration roller pair 3 before the right end. In this way, the same effect as in the first embodiment can be obtained.

  Further, as shown in FIG. 6B, the positions of the transport roller pair 34a and the transport roller pair 34b in the transport direction may be shifted. When the conveying roller pair 34b is rotated faster than the conveying roller pair 34a, the sheet comes into contact with the nip N of the registration roller 3 from the front end of the sheet on the right side of the figure. As a result, it is possible to avoid that the leading edge of the paper abuts against the nip instantaneously, and it is possible to reduce noise generated when the leading edge of the paper contacts the nip.

  Since the conveyance speeds of the conveyance roller pairs 34a and 34b are different, the paper surface of the paper S may be distorted or wrinkled, but after entering the nip N of the registration roller pair 3, the conveyance roller pairs 34a and 34b. It is possible to suppress the occurrence of distortion and wrinkles by making the conveyance speeds of the same or the conveyance speed of the pair of conveyance rollers 34b faster.

  As shown in FIG. 7, the sheet S skewed by the lateral registration plate 13, which is a guide member, and the skew feeding roller 14 a and the parallel roller 14 b is brought into contact with the nip portion of the registration roller 3.

  The sheet S conveyed at right angles to the parallel roller 14b by a pair of conveyance rollers (not shown) is moved in the direction of conveyance toward the lateral resist plate 13 by the first skew feeding roller 14a, as shown in FIG. To be bent. Thereafter, as shown in FIG. 7B, the second inclined feeding roller 14a further enters the nip of the registration roller pair 3 while being in contact with the lateral registration plate 13.

  With such a configuration, an error in the entry angle of the registration roller pair with respect to the nip is unlikely to occur, and the nip and the leading edge of the paper can be gradually brought into contact with each other in a constant skew state every time. It can be reduced.

  The skew feeding roller is not limited to two, but may be one or three or more.

  As shown in FIG. 8, the manual paper feed unit 49 has lateral registration plates 49a and 49b that are skew feeding means, and the paper S is always oblique with respect to the nip of the paper feed roller pair 49c that is a pair of transport rollers. In the sheet feeding device configured to enter the sheet, the noise in the nip of the sheet feeding roller pair 49c can be reduced.

  Further, noise when entering the nip between the transport roller pair and the registration roller pair in the transport mechanism similar to that in FIG. 1 can be greatly reduced.

  The sheet conveying apparatus and sheet feeding apparatus of the present invention are not limited to image forming apparatuses, and can be widely applied to other office machines and the like.

1 is a diagram illustrating an image forming apparatus according to an embodiment. FIG. 2 shows a main part of the sheet conveying apparatus according to the first embodiment, in which (a) is a perspective view and (b) is a plan view. It is a graph which shows the result of the noise test of Example 1 and its comparative example. It is a graph which shows the frequency characteristic of FIG. FIG. 6 is a diagram illustrating a sheet feeding device according to a second embodiment. FIG. 7 shows a main part of a sheet conveying apparatus according to Embodiment 3, wherein (a) is a perspective view and (b) is a plan view. FIG. 10 is a diagram illustrating the configuration and operation of a sheet transport device according to a fourth embodiment. FIG. 9 shows a sheet feeding device according to a fifth embodiment, in which (a) is a perspective view and (b) is a plan view. It is a figure explaining a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transfer drum 2 Fixing unit 3 Registration roller pair 4, 34a, 34b Conveying roller pair 5 Guide lower plate 6 Guide upper plate 7 Image formation part 8 Control part 9, 49 Paper feed part 10, 11 Paper feed cassette 12, 22a, 22b Feed roller 13, 49a, 49b Horizontal registration plate 14a Slope feed roller 14b Parallel roller 49c Feed roller pair

Claims (7)

  A pair of registration rollers for controlling the paper feed timing for the process means, a transport mechanism for transporting a paper material from the paper feed means to the process means via the pair of registration rollers, and the paper in the transport direction of the transport mechanism And a skew feeding means for inclining the leading edge of the sheet material obliquely with respect to the nip of the registration roller pair.   The sheet conveying apparatus according to claim 1, wherein the skew feeding means includes a pair of conveying rollers inclined with respect to the conveying direction of the conveying mechanism.   2. The paper transport according to claim 1, wherein the skew feeding means includes a guide member inclined with respect to the transport direction of the transport mechanism and a skew feeding roller for guiding a side edge of the paper material toward the guide member. apparatus.   2. The sheet conveying apparatus according to claim 1, wherein the skew feeding means includes at least two pairs of conveying rollers having different conveying speeds spaced apart in the width direction of the conveying path of the conveying mechanism.   5. A sheet conveying apparatus according to claim 1, wherein the sheet material introduced into the nip of the registration roller pair is inclined by 0.8 to 3.0 degrees with respect to the conveying direction.   A sheet feeding unit that supplies a sheet material to a process unit by a conveyance mechanism including a pair of conveyance rollers, and the sheet material is inclined from the sheet feeding unit by a predetermined angle with respect to a conveyance direction of the pair of conveyance rollers. A sheet feeding device comprising a skew feeding means for feeding into a transport mechanism.   An image forming unit for forming an image, a registration roller pair for controlling paper feed timing for the image forming unit, and a conveyance for conveying a sheet material from the paper supply unit to the image forming unit through the registration roller pair And a skew mechanism that inclines the sheet material by a predetermined angle with respect to the conveyance direction of the conveyance mechanism, and obliquely enters the leading edge of the sheet material with respect to the nip of the registration roller pair. An image forming apparatus.

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