JP2011006189A - Paper carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise generated when the paper rear end is repelled by a paper feeding part and a curved part, and the paper tip collides strikingly, in a paper carrying device.SOLUTION: This paper carrying device has a fan 80 on a back face of a curved guide 50 for curving the carrying direction of paper S, and is constituted so that an opening part 81 arranged by at least one on a carrying surface of the curved guide 50, is communicated with the downstream side of the fan 80. With such a constitution, a shock when the paper rear end is repelled and the paper tip collides strikingly, can be offset and dispersed by air generated by the fan 80. Thus, the noise can be reduced without generating large impulsive force in paper and a carrying passage.

Description

  The present invention relates to a sheet conveying device used in an image forming apparatus such as a copying machine, a laser beam printer, and an ink jet printer.

  In general, in an image forming apparatus such as a copying machine or a printer, a sheet feeding unit that separates and feeds sheets stacked on a sheet feeding tray one by one, and a sheet conveyance path for effective use of the inside of the housing. In many cases, it has a curved portion to be bent.

  In such a sheet feeding section or a curved section, the sheet feeding tray or guide plate located on the upstream side of the conveyance path and the conveyance path on the downstream side are usually branched from a maintenance aspect. Yes. In this branching section, after the trailing edge of the paper is removed from the paper feed tray or guide plate located on the upstream side of the conveyance path, the trailing edge of the paper is determined by the strength of the paper and the weight (positional energy difference) of the paper. Be repelled. At this time, it collides with a guide plate provided on the downstream side forming the conveyance path, and generates a large noise. This noise becomes louder as the curvature of the curved portion of the conveyance path is smaller because the strain energy stored until the trailing edge of the sheet is repelled increases.

  Also, a large noise is generated when the leading edge of a sheet conveyed from a paper feed tray or a guide plate located on the upstream side of the conveyance path hits a guide plate provided on the downstream side forming the conveyance path. This noise becomes louder because the kinetic energy of the paper increases as the paper conveyance speed increases.

  These noises become a major problem with the recent miniaturization and high speed printing of copiers and printers.

In order to reduce these noises, as conventional technology,
The upstream side of the curved guide is fixedly supported on the upstream guide surface, the free end on the downstream side can be flexibly elastically bent in the thickness direction, and a bent piece folded back on the free end side. It is set as the structure provided with the elastic thin plate currently formed. With such a configuration, the sheet is repelled while absorbing the distortion energy when the trailing edge of the sheet is repelled. (Patent Document 1: Japanese Patent Application Laid-Open No. 2004-269098)
Further, in a paper transport apparatus having a friction pad type paper feed unit that presses a friction pad supported by a pad base against a paper feed roller and separates and feeds the paper, the downstream edge of the pad base is defined as the transport direction. It is set as the structure inclined in the orthogonal direction. With this configuration, the trailing edge of the sheet is prevented from being repelled at once, and noise is prevented. (Patent Document 2: JP 2000-158542 A)
In addition, the signal detected by the paper leading edge detection sensor temporarily stops the paper immediately before the paper leading edge hits the guide plate provided on the downstream side, and then the guide provided on the downstream side at a slow conveyance speed. The noise is reduced by hitting the board. (Patent Document 3: JP-A-6-127753)

JP 2004-269098 A JP 2000-158542 A Japanese Patent Laid-Open No. 6-127753

  However, in the first conventional technique, an unnecessary elastic member must be provided on the guide surface of the sheet. Further, if there is a deviation such as the fixing position of the elastic member being inclined, other noises such as friction may be generated. Furthermore, since it is necessary to secure the position where the elastic member is provided, there is a problem that restrictions are imposed on the formation of the conveyance path.

  In the second prior art, since the downstream edge of the pad base needs to be inclined in the direction orthogonal to the transport direction, a certain distance is secured between the pad base and the downstream guide plate. It was necessary and unnecessary space was needed. In addition, the paper is often transported with a slight skew when feeding, but there is a problem that the effect is reduced for the skewed paper.

  In the third prior art, a control means for temporarily stopping the paper by controlling the transport roller by a signal detected by the paper leading edge detection sensor must be newly installed. Furthermore, there is a problem that throughput is lowered by lowering the sheet conveyance speed.

  Therefore, the present invention has been made in view of the above-described problems, and noise generated when the rear end of the paper is repelled or the front end of the paper collides with a paper feeding unit or a curved part is efficiently processed. It aims to reduce it automatically.

  In order to achieve the above object, the invention according to claim 1 includes a plurality of conveying roller pairs and a plurality of guides for conveying a sheet, and a curved guide for curving the sheet conveying direction. A fan is provided on the back surface, and at least one opening provided on the conveying surface of the curved guide is communicated with the downstream side of the fan.

  According to a second aspect of the present invention, in the first aspect of the present invention, the drive of the fan is synchronized with the drive of the pair of conveying rollers.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the opening is arranged in a horizontal asymmetrical size with respect to the paper transport direction.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the opening is disposed at a position where the sheet rear end portion of the curved guide contacts.

  According to a fifth aspect of the present invention, in the first to third aspects of the invention, the opening is disposed at a position where the leading end of the curved guide contacts.

  With such a configuration, it is possible to cancel and disperse the impact when the trailing edge of the sheet is repelled and when the leading edge of the sheet collides with the air generated by the fan. Therefore, a large impact force is not generated on the paper and the conveyance path, and noise can be reduced.

  As described above, according to the paper transport device of the present invention, noise generated when the rear end of the paper is repelled or the front end of the paper collides with the paper feed unit or the curved portion can be efficiently performed. Can be reduced.

It is explanatory drawing of the image recording apparatus in connection with the 1st Example of this invention. It is explanatory drawing which shows the paper feeding state in connection with the 1st Example of this invention. It is a perspective view of the curved guide concerning the 1st Example of this invention. It is a perspective view of the curved guide with a rib concerning the 1st example of the present invention. It is a perspective view of the curved guide concerning the 2nd Example of this invention. It is a top view of the curved guide concerning the 2nd Example of this invention. It is explanatory drawing which shows the paper feeding state in connection with the 2nd Example of this invention.

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

(First embodiment)
FIG. 1 illustrates a sheet conveying apparatus having a sheet feeding unit that separates and feeds sheets one by one, a pair of conveyance rollers for conveying the fed sheets to a desired portion, and a plurality of guides. The schematic structure of an example of the image recording apparatus containing is shown.

  The image recording apparatus of this example is roughly divided into an image input unit 5 and an image output unit 6.

  The image input unit 5 is, for example, an image information photoelectric reading mechanism. The image input unit 5 inputs image information for recording, performs various processing, and sends the image signal to the image output unit 6. An optical apparatus that projects and exposes a document image on the image carrier of the image forming unit 7 of the image output unit 6 may be used.

  The image output unit 6 is a transfer type image recording mechanism using the transfer drum 1 in this example. The image forming unit 7 carries an image bearing member 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 from the image input unit 5. A transferable recording image such as a toner image is formed on the body. Further, the sheet feeding unit 10 feeds the sheet S as a sheet material. The transfer drum 1 conveys the paper S fed from the paper feed unit to the transfer unit W. The fixing unit 2 performs an image fixing process on the sheet on which the image is transferred by the transfer unit W. The control unit 8 controls all operations of the apparatus.

  The paper feeding unit 10 is an automatic single sheet feeding mechanism built in the image output unit 6. In the sheet feeding unit 10, the sheets S stacked and stored in the sheet feeding cassette are separated and fed one by one in order from the uppermost sheet by the sheet feeding roller 31 based on a sheet feeding start signal.

  The paper feed unit 10 is provided with a paper feed tray 110 that holds recording paper. A spring material 111 that pushes the bottom plate upward by a spring or the like, a bottom plate 112 on which sheets are stacked, and a plurality of recording sheets S stacked on the bottom plate 112 are disposed in the paper feed tray 110. At the top of the recording paper S, a paper feed roller 31 for feeding out the paper is provided. Only the uppermost sheet is separated and fed by the sheet feeding roller 31.

  The fed paper S passes through the curved guide member 50 and is conveyed to the transfer unit. Further, a fan 80 is installed on the back surface of the curved guide member 50, and an opening 81 that is open at a position where the rear end of the sheet at the center of the conveyance surface of the curved guide member 50 contacts is communicated downstream of the fan 80. Yes. The upstream of the fan communicates with the outside of the housing, and the air outside the housing is jetted into the opening 81 by driving the fan 80. The fan is controlled by the control unit 8.

  2 (a) to 2 (c) are enlarged views (side views) of the conveyance path separated and fed by the sheet feeding unit 10, and FIG. 3 is a view of the curved guide member 50 in FIG. FIG. When the sheet S is fed, the leading end of the sheet first strikes the curved guide member 50 (FIG. 2A), and then passes through the curved guide member 50 and the trailing end is fed downstream of the curved guide member 50. It comes off from the tray (FIG. 2B), and its rear end collides with the curved guide plate member 50 (FIG. 2C). The magnitude of noise at this time increases as the conveyance speed of the sheet S increases, the bending rigidity increases, and the bending curvature increases.

  Therefore, when the fan is driven during such conveyance, air is ejected from the circular opening 81 having a diameter of about 10 [mm] shown in FIG. 3 and the sheet collides with the curved guide member 50. Noise can be offset and noise can be reduced. However, the shape of the opening is not limited to a circle, and may be any shape as long as air can be ejected, such as a quadrangle. Further, by controlling the driving of the fan 80 by the control unit 8 so as to synchronize with the driving of the paper feed roller 31, unnecessary operation of the fan 80 is eliminated at the standby time when the paper is not conveyed. And more efficient noise reduction.

  In this embodiment, the fan 80 is a general axial fan having a 120 [mm] square. By slowly driving at a low rotational speed of about several hundreds [rpm], the influence of noise generated from the fan itself does not matter. As a result, the impact when the trailing edge of the sheet collides with the curved guide member 50 can be offset, and the noise can be reduced by several dB.

  Note that ribs 52 may be provided on the conveyance surface of the curved guide 50 as shown in FIG. 4 for the purpose of reducing the electrostatic force acting between the curved guide 50 and the paper S. Even in the curved guide 50 having such a configuration, the present invention can provide the same effect as described above by providing the opening 81 on the conveyance surface of the curved guide 50 and communicating with the downstream of the fan.

  Further, in the embodiment described with reference to FIG. 1, the fan is disposed in the vicinity of the curved guide member. However, if the air generated by the fan is communicated by a flow path or the like so as to be ejected from the opening portion, both fans are not necessarily provided. Need not be placed close together.

(Second embodiment)
A second embodiment of the present invention will be described. FIG. 5 is an explanatory view of the bending guide 50 in FIG. 1 as viewed obliquely from above. Similarly, FIG. 6 is an explanatory diagram viewed from directly above. As shown in FIGS. 5 and 6, the opening 81 of the curved guide 50 is arranged in a laterally asymmetric size with respect to the paper conveyance direction. As a result, the air flow generated by driving the fan 80 is ejected from the opening 81 with an asymmetrical strength as shown in FIG. Therefore, the conveyed sheet S is twisted in the conveyance path width direction with respect to the center line in the sheet width direction. FIG. 7 shows a state immediately before the sheet S is conveyed from the sheet feeding roller and the leading end of the sheet S hits the curved guide 50. In this way, since the sheet collides with the conveyance path in a twisted state, the impact force is dispersed in time, and sudden noise can be reduced.

  In this embodiment, circular openings of 10 [mm] to 6 [mm] are arranged asymmetrically with a size of 1 [mm]. Also, a total of 10 openings were provided for the paper conveyance direction, the position where the leading edge of the sheet contacts and the position where the trailing edge of the sheet contact. A general axial fan with a 120 [mm] square was used as the fan 80, and the fan 80 was slowly driven at a low rotational speed of about several hundreds [rpm]. As a result, the impact when the trailing edge of the sheet and the leading edge of the sheet collide with the curved guide member 50 can be not only offset by air but also dispersed, and noise can be further reduced.

DESCRIPTION OF SYMBOLS 1 Transfer drum 2 Fixing unit 5 Image input part 6 Image output part 7 Image forming part 8 Control part 10 Paper feed part unit 31 Paper feed roller 40 Guide plate 50 Curved guide 52 Rib 60 Branch part 80 Fan 81 Opening part 110 Paper feed tray 111 Spring material 112 Bottom plate S Paper W Transfer section

Claims (5)

  A plurality of conveyance roller pairs and a plurality of guides for conveying the paper; a fan is provided on the back of the curved guide for curving the conveyance direction of the paper; and at least one is provided on the conveyance surface of the curved guide An opening is communicated with the downstream of the fan.   The sheet conveying device according to claim 1, wherein the driving of the fan is synchronized with the driving of the pair of conveying rollers.   3. The sheet conveying device according to claim 1, wherein the opening is arranged in a horizontal asymmetrical size in a horizontal direction with respect to a sheet conveying direction.   4. The sheet conveying device according to claim 1, wherein the opening is arranged at a position where a sheet rear end portion of the curved guide contacts. 5.   4. The sheet conveying device according to claim 1, wherein the opening is disposed at a position where a sheet leading end of the curved guide contacts. 5.

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